Prospective feasibility analysis of a novel off-line approach for MR-guided radiotherapy.

PubMed

Bostel, Tilman; Pfaffenberger, Asja; Delorme, Stefan; Dreher, Constantin; Echner, Gernot; Haering, Peter; Lang, Clemens; Splinter, Mona; Laun, Frederik; Müller, Marco; Jäkel, Oliver; Debus, Jürgen; Huber, Peter E; Sterzing, Florian; Nicolay, Nils H

2018-05-01

The present work aimed to analyze the feasibility of a shuttle-based MRI-guided radiation therapy (MRgRT) in the treatment of pelvic malignancies. 20 patients with pelvic malignancies were included in this prospective feasibility analysis. Patients underwent daily MRI in treatment position prior to radiotherapy at the German Cancer Research Center. Positional inaccuracies, time and patient compliance were assessed for the application of off-line MRgRT. In 78% of applied radiation fractions, MR imaging for position verification could be performed without problems. Additionally, treatment-related side effects and reduced patient compliance were only responsible for omission of MRI in 9% of radiation fractions. The study workflow took a median time of 61 min (range 47-99 min); duration for radiotherapy alone was 13 min (range 7-26 min). Patient positioning, MR imaging and CT imaging including patient repositioning and the shuttle transfer required median times of 10 min (range 7-14 min), 26 min (range 15-60 min), 5 min (range 3-8 min) and 8 min (range 2-36 min), respectively. To assess feasibility of shuttle-based MRgRT, the reference point coordinates for the x, y and z axis were determined for the MR images and CT obtained prior to the first treatment fraction and correlated with the coordinates of the planning CT. In our dataset, the median positional difference between MR imaging and CT-based imaging based on fiducial matching between MR and CT imaging was equal to or less than 2 mm in all spatial directions. The limited space in the MR scanner influenced patient selection, as the bore of the scanner had to accommodate the immobilization device and the constructed stereotactic frame. Therefore, obese, extremely muscular or very tall patients could not be included in this trial in addition to patients for whom exposure to MRI was generally judged inappropriate. This trial demonstrated for the first time the feasibility and patient compliance of a shuttle-based off-line approach to MRgRT of pelvic malignancies.

Dosimetric evaluation of synthetic CT for magnetic resonance-only based radiotherapy planning of lung cancer.

PubMed

Wang, Hesheng; Chandarana, Hersh; Block, Kai Tobias; Vahle, Thomas; Fenchel, Matthias; Das, Indra J

2017-06-26

Interest in MR-only treatment planning for radiation therapy is growing rapidly with the emergence of integrated MRI/linear accelerator technology. The purpose of this study was to evaluate the feasibility of using synthetic CT images generated from conventional Dixon-based MRI scans for radiation treatment planning of lung cancer. Eleven patients who underwent whole-body PET/MR imaging following a PET/CT exam were randomly selected from an ongoing prospective IRB-approved study. Attenuation maps derived from the Dixon MR Images and atlas-based method was used to create CT data (synCT). Treatment planning for radiation treatment of lung cancer was optimized on the synCT and subsequently copied to the registered CT (planCT) for dose calculation. Planning target volumes (PTVs) with three sizes and four different locations in the lung were planned for irradiation. The dose-volume metrics comparison and 3D gamma analysis were performed to assess agreement between the synCT and CT calculated dose distributions. Mean differences between PTV doses on synCT and CT across all the plans were -0.1% ± 0.4%, 0.1% ± 0.5%, and 0.4% ± 0.5% for D95, D98 and D100, respectively. Difference in dose between the two datasets for organs at risk (OARs) had average differences of -0.14 ± 0.07 Gy, 0.0% ± 0.1%, and -0.1% ± 0.2% for maximum spinal cord, lung V20, and heart V40 respectively. In patient groups based on tumor size and location, no significant differences were observed in the PTV and OARs dose-volume metrics (p > 0.05), except for the maximum spinal-cord dose when the target volumes were located at the lung apex (p = 0.001). Gamma analysis revealed a pass rate of 99.3% ± 1.1% for 2%/2 mm (dose difference/distance to agreement) acceptance criteria in every plan. The synCT generated from Dixon-based MRI allows for dose calculation of comparable accuracy to the standard CT for lung cancer treatment planning. The dosimetric agreement between synCT and CT calculated doses warrants further development of a MR-only workflow for radiotherapy of lung cancer.

An anthropomorphic multimodality (CT/MRI) head phantom prototype for end-to-end tests in ion radiotherapy.

PubMed

Gallas, Raya R; Hünemohr, Nora; Runz, Armin; Niebuhr, Nina I; Jäkel, Oliver; Greilich, Steffen

2015-12-01

With the increasing complexity of external beam therapy "end-to-end" tests are intended to cover every step from therapy planning through to follow-up in order to fulfill the higher demands on quality assurance. As magnetic resonance imaging (MRI) has become an important part of the treatment process, established phantoms such as the Alderson head cannot fully be used for those tests and novel phantoms have to be developed. Here, we present a feasibility study of a customizable multimodality head phantom. It is initially intended for ion radiotherapy but may also be used in photon therapy. As basis for the anthropomorphic head shape we have used a set of patient computed tomography (CT) images. The phantom recipient consisting of epoxy resin was produced by using a 3D printer. It includes a nasal air cavity, a cranial bone surrogate (based on dipotassium phosphate), a brain surrogate (based on agarose gel), and a surrogate for cerebrospinal fluid (based on distilled water). Furthermore, a volume filled with normoxic dosimetric gel mimicked a tumor. The entire workflow of a proton therapy could be successfully applied to the phantom. CT measurements revealed CT numbers agreeing with reference values for all surrogates in the range from 2 HU to 978 HU (120 kV). MRI showed the desired contrasts between the different phantom materials especially in T2-weighted images (except for the bone surrogate). T2-weighted readout of the polymerization gel dosimeter allowed approximate range verification. Copyright © 2015. Published by Elsevier GmbH.

Improved human observer performance in digital reconstructed radiograph verification in head and neck cancer radiotherapy.

PubMed

Sturgeon, Jared D; Cox, John A; Mayo, Lauren L; Gunn, G Brandon; Zhang, Lifei; Balter, Peter A; Dong, Lei; Awan, Musaddiq; Kocak-Uzel, Esengul; Mohamed, Abdallah Sherif Radwan; Rosenthal, David I; Fuller, Clifton David

2015-10-01

Digitally reconstructed radiographs (DRRs) are routinely used as an a priori reference for setup correction in radiotherapy. The spatial resolution of DRRs may be improved to reduce setup error in fractionated radiotherapy treatment protocols. The influence of finer CT slice thickness reconstruction (STR) and resultant increased resolution DRRs on physician setup accuracy was prospectively evaluated. Four head and neck patient CT-simulation images were acquired and used to create DRR cohorts by varying STRs at 0.5, 1, 2, 2.5, and 3 mm. DRRs were displaced relative to a fixed isocenter using 0-5 mm random shifts in the three cardinal axes. Physician observers reviewed DRRs of varying STRs and displacements and then aligned reference and test DRRs replicating daily KV imaging workflow. A total of 1,064 images were reviewed by four blinded physicians. Observer errors were analyzed using nonparametric statistics (Friedman's test) to determine whether STR cohorts had detectably different displacement profiles. Post hoc bootstrap resampling was applied to evaluate potential generalizability. The observer-based trial revealed a statistically significant difference between cohort means for observer displacement vector error ([Formula: see text]) and for [Formula: see text]-axis [Formula: see text]. Bootstrap analysis suggests a 15% gain in isocenter translational setup error with reduction of STR from 3 mm to [Formula: see text]2 mm, though interobserver variance was a larger feature than STR-associated measurement variance. Higher resolution DRRs generated using finer CT scan STR resulted in improved observer performance at shift detection and could decrease operator-dependent geometric error. Ideally, CT STRs [Formula: see text]2 mm should be utilized for DRR generation in the head and neck.

Clinical validation of FDG-PET/CT in the radiation treatment planning for patients with oesophageal cancer.

PubMed

Muijs, Christina T; Beukema, Jannet C; Woutersen, Dankert; Mul, Veronique E; Berveling, Maaike J; Pruim, Jan; van der Jagt, Eric J; Hospers, Geke A P; Groen, Henk; Plukker, John Th; Langendijk, Johannes A

2014-11-01

The aim of this prospective study was to determine the proportion of locoregional recurrences (LRRs) that could have been prevented if radiotherapy treatment planning for oesophageal cancer was based on PET/CT instead of CT. Ninety oesophageal cancer patients, eligible for high dose (neo-adjuvant) (chemo)radiotherapy, were included. All patients underwent a planning FDG-PET/CT-scan. Radiotherapy target volumes (TVs) were delineated on CT and patients were treated according to the CT-based treatment plans. The PET images remained blinded. After treatment, TVs were adjusted based on PET/CT, when appropriate. Follow up included CT-thorax/abdomen every 6months. If LRR was suspected, a PET/CT was conducted and the site of recurrence was compared to the original TVs. If the LRR was located outside the CT-based clinical TV (CTV) and inside the PET/CT-based CTV, we considered this LRR possibly preventable. Based on PET/CT, the gross tumour volume (GTV) was larger in 23% and smaller in 27% of the cases. In 32 patients (36%), >5% of the PET/CT-based GTV would be missed if the treatment planning was based on CT. The median follow up was 29months. LRRs were seen in 10 patients (11%). There were 3 in-field recurrences, 4 regional recurrences outside both CT-based and PET/CT-based CTV and 3 recurrences at the anastomosis without changes in TV by PET/CT; none of these recurrences were considered preventable by PET/CT. No LRR was found after CT-based radiotherapy that could have been prevented by PET/CT. The value of PET/CT for radiotherapy seems limited. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Preparation and fabrication of a full-scale, sagittal-sliced, 3D-printed, patient-specific radiotherapy phantom.

PubMed

Craft, Daniel F; Howell, Rebecca M

2017-09-01

Patient-specific 3D-printed phantoms have many potential applications, both research and clinical. However, they have been limited in size and complexity because of the small size of most commercially available 3D printers as well as material warping concerns. We aimed to overcome these limitations by developing and testing an effective 3D printing workflow to fabricate a large patient-specific radiotherapy phantom with minimal warping errors. In doing so, we produced a full-scale phantom of a real postmastectomy patient. We converted a patient's clinical CT DICOM data into a 3D model and then sliced the model into eleven 2.5-cm-thick sagittal slices. The slices were printed with a readily available thermoplastic material representing all body tissues at 100% infill, but with air cavities left open. Each slice was printed on an inexpensive and commercially available 3D printer. Once the printing was completed, the slices were placed together for imaging and verification. The original patient CT scan and the assembled phantom CT scan were registered together to assess overall accuracy. The materials for the completed phantom cost $524. The printed phantom agreed well with both its design and the actual patient. Individual slices differed from their designs by approximately 2%. Registered CT images of the assembled phantom and original patient showed excellent agreement. Three-dimensional printing the patient-specific phantom in sagittal slices allowed a large phantom to be fabricated with high accuracy. Our results demonstrate that our 3D printing workflow can be used to make large, accurate, patient-specific phantoms at 100% infill with minimal material warping error. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

Automated replication of cone beam CT-guided treatments in the Pinnacle(3) treatment planning system for adaptive radiotherapy.

PubMed

Hargrave, Catriona; Mason, Nicole; Guidi, Robyn; Miller, Julie-Anne; Becker, Jillian; Moores, Matthew; Mengersen, Kerrie; Poulsen, Michael; Harden, Fiona

2016-03-01

Time-consuming manual methods have been required to register cone-beam computed tomography (CBCT) images with plans in the Pinnacle(3) treatment planning system in order to replicate delivered treatments for adaptive radiotherapy. These methods rely on fiducial marker (FM) placement during CBCT acquisition or the image mid-point to localise the image isocentre. A quality assurance study was conducted to validate an automated CBCT-plan registration method utilising the Digital Imaging and Communications in Medicine (DICOM) Structure Set (RS) and Spatial Registration (RE) files created during online image-guided radiotherapy (IGRT). CBCTs of a phantom were acquired with FMs and predetermined setup errors using various online IGRT workflows. The CBCTs, DICOM RS and RE files were imported into Pinnacle(3) plans of the phantom and the resulting automated CBCT-plan registrations were compared to existing manual methods. A clinical protocol for the automated method was subsequently developed and tested retrospectively using CBCTs and plans for six bladder patients. The automated CBCT-plan registration method was successfully applied to thirty-four phantom CBCT images acquired with an online 0 mm action level workflow. Ten CBCTs acquired with other IGRT workflows required manual workarounds. This was addressed during the development and testing of the clinical protocol using twenty-eight patient CBCTs. The automated CBCT-plan registrations were instantaneous, replicating delivered treatments in Pinnacle(3) with errors of ±0.5 mm. These errors were comparable to mid-point-dependant manual registrations but superior to FM-dependant manual registrations. The automated CBCT-plan registration method quickly and reliably replicates delivered treatments in Pinnacle(3) for adaptive radiotherapy.

[Integration of the radiotherapy irradiation planning in the digital workflow].

PubMed

Röhner, F; Schmucker, M; Henne, K; Momm, F; Bruggmoser, G; Grosu, A-L; Frommhold, H; Heinemann, F E

2013-02-01

At the Clinic of Radiotherapy at the University Hospital Freiburg, all relevant workflow is paperless. After implementing the Operating Schedule System (OSS) as a framework, all processes are being implemented into the departmental system MOSAIQ. Designing a digital workflow for radiotherapy irradiation planning is a large challenge, it requires interdisciplinary expertise and therefore the interfaces between the professions also have to be interdisciplinary. For every single step of radiotherapy irradiation planning, distinct responsibilities have to be defined and documented. All aspects of digital storage, backup and long-term availability of data were considered and have already been realized during the OSS project. After an analysis of the complete workflow and the statutory requirements, a detailed project plan was designed. In an interdisciplinary workgroup, problems were discussed and a detailed flowchart was developed. The new functionalities were implemented in a testing environment by the Clinical and Administrative IT Department (CAI). After extensive tests they were integrated into the new modular department system. The Clinic of Radiotherapy succeeded in realizing a completely digital workflow for radiotherapy irradiation planning. During the testing phase, our digital workflow was examined and afterwards was approved by the responsible authority.

TU-AB-303-03: CBCT-Based On-Site Simulation, Planning, and Delivery (OSPD) for Whole Brain Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Le, A; Choe, K; Jiang, S

2015-06-15

Purpose: To demonstrate the feasibility of a CBCT-based on-site simulation, planning, and delivery (OSPD) for whole brain radiotherapy, in which all steps from imaging, planning to treatment delivery are performed at the treatment unit in one appointment time slot. This work serves as the proof of concept for future OSPD single fraction radiation therapy. Methods: An integrated on-site imaging, planning and delivery workflow was developed and tested for whole brain radiotherapy. An automated two-opposed-oblique-beam plan is created by utilizing the treatment planning system scripting and simple field-in-field IMRT. The IMRT plan is designed with maximum 8 control points to covermore » the target volume consisting of the brain to C1/C2 of the spinal cord, with dose homogeneity criteria from −5% to +7% of the prescription dose. Due to inaccuracy of reconstructed Hounsfield unit numbers in CBCT images, the dose distribution is calculated with non-heterogeneity correction introducing only clinically insignificant dose discrepancy. A coherent and synchronized workflow was designed for a team of attending physician, physicist, therapists, and dosimetrist to work closely with the ability to quickly modify, approve, and implement the treatment. Results: Thirty-one patients have been treated with this OSPD treatment, without compromising the plan quality compared to our regular clinically used parallel apposed 2D plans. The average time for these procedures are 48.02 ±11.55 minutes from the time patient entered the treatment room until s/he exited, and 35.09 ±10.35 minutes from starting CBCT until last beam delivered. This time duration is comparable to the net time when individual tasks are summed up during our regular CT- based whole brain planning and delivery. Conclusions: The OSPD whole brain treatment has been tested to be clinically feasible. The next step is to further improve the efficiency and to streamline the workflow. Other disease sites will be also tested with this new technology.« less

SU-F-J-81: Evaluation of Automated Deformable Registration Between Planning Computed Tomography (CT) and Daily Cone Beam CT Images Over the Course of Prostate Cancer Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matney, J; Hammers, J; Kaidar-Person, O

2016-06-15

Purpose: To compute daily dose delivered during radiotherapy, deformable registration needs to be relatively fast, automated, and accurate. The aim of this study was to evaluate the performance of commercial deformable registration software for deforming between two modalities: planning computed tomography (pCT) images acquired for treatment planning and cone beam (CB) CT images acquired prior to each fraction of prostate cancer radiotherapy. Methods: A workflow was designed using MIM Software™ that aligned and deformed pCT into daily CBCT images in two steps: (1) rigid shifts applied after daily CBCT imaging to align patient anatomy to the pCT and (2) normalizedmore » intensity-based deformable registration to account for interfractional anatomical variations. The physician-approved CTV and organ and risk (OAR) contours were deformed from the pCT to daily CBCT over the course of treatment. The same structures were delineated on each daily CBCT by a radiation oncologist. Dice similarity coefficient (DSC) mean and standard deviations were calculated to quantify the deformable registration quality for prostate, bladder, rectum and femoral heads. Results: To date, contour comparisons have been analyzed for 31 daily fractions of 2 of 10 of the cohort. Interim analysis shows that right and left femoral head contours demonstrate the highest agreement (DSC: 0.96±0.02) with physician contours. Additionally, deformed bladder (DSC: 0.81±0.09) and prostate (DSC: 0.80±0.07) have good agreement with physician-defined daily contours. Rectum contours have the highest variations (DSC: 0.66±0.10) between the deformed and physician-defined contours on daily CBCT imaging. Conclusion: For structures with relatively high contrast boundaries on CBCT, the MIM automated deformable registration provided accurate representations of the daily contours during treatment delivery. These findings will permit subsequent investigations to automate daily dose computation from CBCT. However, improved methods need to be investigated to improve deformable results for rectum contours.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Giaddui, T; Li, N; Moore, K

Purpose: To establish a workflow for NRG-GY006 IMRT pre-treatment reviews, incorporating advanced radiotherapy technologies being evaluated as part of the clinical trial. Methods: Pre-Treatment reviews are required for every IMRT case as part of NRG-GY006 (a randomized phase II trial of radiation therapy and cisplatin alone or in combination with intravenous triapine in women with newly diagnosed bulky stage I B2, stage II, IIIB, or IVA cancer of the uterine cervix or stage II-IVA vaginal cancer. The pretreatment review process includes structures review and generating an active bone marrow(ABM)- to be used as an avoidance structure during IMRT optimization- andmore » evaluating initial IMRT plan quality using knowledgeengineering based planning (KBP). Institutions will initially submit their simulation CT scan, structures file and PET/CT to IROC QA center for generating ABM. The ABM will be returned to the institution for use in planning. Institutions will then submit an initial IMRT plan for review and will receive information back following implementation of a KBP algorithm, for use in re-optimization, before submitting the final IMRT used for treatment. Results: ABM structure is generated using MIM vista software (Version 6.5, MIM corporation, Inc.). Here, the planning CT and the diagnostic PET/CT are fused and a sub threshold structure is auto segmented above the mean value of the SUV of the bone marrow. The generated ABM were compared with those generated with other software system (e.g. Velocity, Varian) and Dice coefficient (reflects the overlap of structures) ranged between 80 – 90% was achieved. A KBP model was built in Varian Eclipse TPS using the RapidPlan KBP software to perform plan quality assurance. Conclusion: The workflow for IMRT pretreatment reviews has been established. It represents a major improvement of NRG Oncology clinical trial quality assurance and incorporates the latest radiotherapy technologies as part of NCI clinical trials. This project was supported by grants U24CA180803 (IROC), UG1CA189867 (NCORP), U10CA180868 (NRG Oncology Operations), U10CA180822 (NRG Oncology SDMC) from the National Cancer Institute (NCI) and PA CURE grant.« less

TH-AB-BRA-04: Dosimetric Evaluation of MR-Guided HDR Brachytherapy Planning for Cervical Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamio, Y; Barkati, M; Beliveau-Nadeau, D

2016-06-15

Purpose: To perform a retrospective study on 16 patients that had both CT and T2-weighted MR scans done at first fraction using the Utrecht CT/MR applicator (Elekta Brachytherapy) in order to evaluate uncertainties associated with an MR-only planning workflow. Methods: MR-workflow uncertainties were classified in three categories: reconstruction, registration and contouring. A systematic comparison of the CT and MR contouring, manual reconstruction and optimization process was performed to evaluate the impact of these uncertainties on the recommended GEC ESTRO DVH parameters: D90% and V100% for HR-CTV as well as D2cc for bladder, rectum, sigmoid colon and small bowel. This comparisonmore » was done using the following four steps: 1. Catheter reconstruction done on MR images with original CT-plan contours and dwell times. 2. OAR contours adjusted on MR images with original CT-plan reconstruction and dwell times. 3. Both reconstruction and contours done on MR images with original CT-plan dwell times. 4. Entire MR-based workflow optimized dwell times reimported to the original CT-plan. Results: The MR-based reconstruction process showed average D2cc deviations of 4.5 ± 3.0%, 1.5 ± 2.0%, 2.5 ± 2.0% and 2.0 ± 1.0% for the bladder, rectum, sigmoid colon and small bowels respectively with a maximum of 10%, 6%, 6% and 4%. The HR-CTV’s D90% and V100% average deviations was found to be 4.0 ± 3.0%, and 2.0 ± 2.0% respectively with a maximum of 10% and 6%. Adjusting contours on MR-images was found to have a similar impact. Finally, the optimized MR-based workflow dwell times were found to still give acceptable plans when re-imported to the original CT-plan which validated the entire workflow. Conclusion: This work illustrates a systematic validation method for centers wanting to move towards an MR-only workflow. This work will be expanded to model based reconstruction, PD-weighted images and other types of applicators.« less

Technical Note: scuda: A software platform for cumulative dose assessment.

PubMed

Park, Seyoun; McNutt, Todd; Plishker, William; Quon, Harry; Wong, John; Shekhar, Raj; Lee, Junghoon

2016-10-01

Accurate tracking of anatomical changes and computation of actually delivered dose to the patient are critical for successful adaptive radiation therapy (ART). Additionally, efficient data management and fast processing are practically important for the adoption in clinic as ART involves a large amount of image and treatment data. The purpose of this study was to develop an accurate and efficient Software platform for CUmulative Dose Assessment (scuda) that can be seamlessly integrated into the clinical workflow. scuda consists of deformable image registration (DIR), segmentation, dose computation modules, and a graphical user interface. It is connected to our image PACS and radiotherapy informatics databases from which it automatically queries/retrieves patient images, radiotherapy plan, beam data, and daily treatment information, thus providing an efficient and unified workflow. For accurate registration of the planning CT and daily CBCTs, the authors iteratively correct CBCT intensities by matching local intensity histograms during the DIR process. Contours of the target tumor and critical structures are then propagated from the planning CT to daily CBCTs using the computed deformations. The actual delivered daily dose is computed using the registered CT and patient setup information by a superposition/convolution algorithm, and accumulated using the computed deformation fields. Both DIR and dose computation modules are accelerated by a graphics processing unit. The cumulative dose computation process has been validated on 30 head and neck (HN) cancer cases, showing 3.5 ± 5.0 Gy (mean±STD) absolute mean dose differences between the planned and the actually delivered doses in the parotid glands. On average, DIR, dose computation, and segmentation take 20 s/fraction and 17 min for a 35-fraction treatment including additional computation for dose accumulation. The authors developed a unified software platform that provides accurate and efficient monitoring of anatomical changes and computation of actually delivered dose to the patient, thus realizing an efficient cumulative dose computation workflow. Evaluation on HN cases demonstrated the utility of our platform for monitoring the treatment quality and detecting significant dosimetric variations that are keys to successful ART.

Technical Note: SCUDA: A software platform for cumulative dose assessment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Seyoun; McNutt, Todd; Quon, Harry

Purpose: Accurate tracking of anatomical changes and computation of actually delivered dose to the patient are critical for successful adaptive radiation therapy (ART). Additionally, efficient data management and fast processing are practically important for the adoption in clinic as ART involves a large amount of image and treatment data. The purpose of this study was to develop an accurate and efficient Software platform for CUmulative Dose Assessment (SCUDA) that can be seamlessly integrated into the clinical workflow. Methods: SCUDA consists of deformable image registration (DIR), segmentation, dose computation modules, and a graphical user interface. It is connected to our imagemore » PACS and radiotherapy informatics databases from which it automatically queries/retrieves patient images, radiotherapy plan, beam data, and daily treatment information, thus providing an efficient and unified workflow. For accurate registration of the planning CT and daily CBCTs, the authors iteratively correct CBCT intensities by matching local intensity histograms during the DIR process. Contours of the target tumor and critical structures are then propagated from the planning CT to daily CBCTs using the computed deformations. The actual delivered daily dose is computed using the registered CT and patient setup information by a superposition/convolution algorithm, and accumulated using the computed deformation fields. Both DIR and dose computation modules are accelerated by a graphics processing unit. Results: The cumulative dose computation process has been validated on 30 head and neck (HN) cancer cases, showing 3.5 ± 5.0 Gy (mean±STD) absolute mean dose differences between the planned and the actually delivered doses in the parotid glands. On average, DIR, dose computation, and segmentation take 20 s/fraction and 17 min for a 35-fraction treatment including additional computation for dose accumulation. Conclusions: The authors developed a unified software platform that provides accurate and efficient monitoring of anatomical changes and computation of actually delivered dose to the patient, thus realizing an efficient cumulative dose computation workflow. Evaluation on HN cases demonstrated the utility of our platform for monitoring the treatment quality and detecting significant dosimetric variations that are keys to successful ART.« less

Intensity-based dual model method for generation of synthetic CT images from standard T2-weighted MR images - Generalized technique for four different MR scanners.

PubMed

Koivula, Lauri; Kapanen, Mika; Seppälä, Tiina; Collan, Juhani; Dowling, Jason A; Greer, Peter B; Gustafsson, Christian; Gunnlaugsson, Adalsteinn; Olsson, Lars E; Wee, Leonard; Korhonen, Juha

2017-12-01

Recent studies have shown that it is possible to conduct entire radiotherapy treatment planning (RTP) workflow using only MR images. This study aims to develop a generalized intensity-based method to generate synthetic CT (sCT) images from standard T2-weighted (T2 w ) MR images of the pelvis. This study developed a generalized dual model HU conversion method to convert standard T2 w MR image intensity values to synthetic HU values, separately inside and outside of atlas-segmented bone volume contour. The method was developed and evaluated with 20 and 35 prostate cancer patients, respectively. MR images with scanning sequences in clinical use were acquired with four different MR scanners of three vendors. For the generated synthetic CT (sCT) images of the 35 prostate patients, the mean (and maximal) HU differences in soft and bony tissue volumes were 16 ± 6 HUs (34 HUs) and -46 ± 56 HUs (181 HUs), respectively, against the true CT images. The average of the PTV mean dose difference in sCTs compared to those in true CTs was -0.6 ± 0.4% (-1.3%). The study provides a generalized method for sCT creation from standard T2 w images of the pelvis. The method produced clinically acceptable dose calculation results for all the included scanners and MR sequences. Copyright © 2017 Elsevier B.V. All rights reserved.

SU-F-T-617: Remotely Pre-Planned Stereotactic Ablative Radiation Therapy: Validation of Treatment Plan Quality

DOE Office of Scientific and Technical Information (OSTI.GOV)

Juang, T; Bush, K; Loo, B

Purpose: We propose a workflow to improve access to stereotactic ablative radiation therapy (SABR) for rural patients. When implemented, a separate trip to the central facility for simulation can be eliminated. Two elements are required: (1) Fabrication of custom immobilization devices to match positioning on prior diagnostic CT (dxCT). (2) Remote radiation pre-planning on dxCT, with transfer of contours/plan to simulation CT (simCT) and initiation of treatment same-day or next day. In this retrospective study, we validated part 2 of the workflow using patients already treated with SABR for upper lobe lung tumors. Methods: Target/normal structures were contoured on dxCT;more » a plan was created and approved by the physician. Structures were transferred to simCT using deformable image registration and the plan was re-optimized on simCT. Plan quality was evaluated through comparison to gold-standard structures contoured on simCT and a gold-standard plan based on these structures. Workflow-generated plan quality in this study represents a worst-case scenario as these patients were not treated using custom immobilization to match dxCT position as would be done when the workflow is implemented clinically. Results: 5/6 plans created through the pre-planning workflow were clinically acceptable. For all six plans, the gold-standard GTV received full prescription dose, along with median PTV V95%=95.2% and median PTV D95%=95.4%. Median GTV DSC=0.80, indicating high degree of similarity between the deformed and gold-standard GTV contours despite small GTV sizes (mean=3.0cc). One outlier (DSC=0.49) resulted in inadequate PTV coverage (V95%=62.9%) in the workflow plan; in clinical practice, this mismatch between deformed/gold-standard GTV would be revised by the physician after deformable registration. For all patients, normal tissue doses were comparable to the gold-standard plan and well within constraints. Conclusion: Pre-planning SABR cases on diagnostic imaging generated clinically acceptable plans. Coupled with rapid-prototyped custom immobilization, this workflow may improve treatment access for rural patients.« less

Ultrasound Imaging in Radiation Therapy: From Interfractional to Intrafractional Guidance

PubMed Central

Western, Craig; Hristov, Dimitre

2015-01-01

External beam radiation therapy (EBRT) is included in the treatment regimen of the majority of cancer patients. With the proliferation of hypofractionated radiotherapy treatment regimens, such as stereotactic body radiation therapy (SBRT), interfractional and intrafractional imaging technologies are becoming increasingly critical to ensure safe and effective treatment delivery. Ultrasound (US)-based image guidance systems offer real-time, markerless, volumetric imaging with excellent soft tissue contrast, overcoming the limitations of traditional X-ray or computed tomography (CT)-based guidance for abdominal and pelvic cancer sites, such as the liver and prostate. Interfractional US guidance systems have been commercially adopted for patient positioning but suffer from systematic positioning errors induced by probe pressure. More recently, several research groups have introduced concepts for intrafractional US guidance systems leveraging robotic probe placement technology and real-time soft tissue tracking software. This paper reviews various commercial and research-level US guidance systems used in radiation therapy, with an emphasis on hardware and software technologies that enable the deployment of US imaging within the radiotherapy environment and workflow. Previously unpublished material on tissue tracking systems and robotic probe manipulators under development by our group is also included. PMID:26180704

Quantification of tumor mobility during the breathing cycle using 3D dynamic MRI

NASA Astrophysics Data System (ADS)

Schoebinger, Max; Plathow, Christian; Wolf, Ivo; Kauczor, Hans-Ulrich; Meinzer, Hans-Peter

2006-03-01

Respiration causes movement and shape changes in thoracic tumors, which has a direct influence on the radio-therapy planning process. Current methods for the estimation of tumor mobility are either two-dimensional (fluoroscopy, 2D dynamic MRI) or based on radiation (3D (+t) CT, implanted gold markers). With current advances in dynamic MRI acquisition, 3D+t image sequences of the thorax can be acquired covering the thorax over the whole breathing cycle. In this work, methods are presented for the interactive segmentation of tumors in dynamic images, the calculation of tumor trajectories, dynamic tumor volumetry and dynamic tumor rotation/deformation based on 3D dynamic MRI. For volumetry calculation, a set of 21 related partial volume correcting volumetry algorithms has been evaluated based on tumor surrogates. Conventional volumetry based on voxel counting yielded a root mean square error of 29% compared to a root mean square error of 11% achieved by the algorithm performing best among the different volumetry methods. The new workflow has been applied to a set of 26 patients. Preliminary results indicate, that 3D dynamic MRI reveals important aspects of tumor behavior during the breathing cycle. This might imply the possibility to further improve high-precision radiotherapy techniques.

Role of computed tomography and [18F] fluorodeoxyglucose positron emission tomography image fusion in conformal radiotherapy of non-small cell lung cancer: a comparison with standard techniques with and without elective nodal irradiation.

PubMed

Ceresoli, Giovanni Luca; Cattaneo, Giovanni Mauro; Castellone, Pietro; Rizzos, Giovanna; Landoni, Claudio; Gregorc, Vanesa; Calandrino, Riccardo; Villa, Eugenio; Messa, Cristina; Santoro, Armando; Fazio, Ferruccio

2007-01-01

Mediastinal elective node irradiation (ENI) in patients with non-small cell lung cancer candidate to radical radiotherapy is controversial. In this study, the impact of co-registered [18F]fluorodeoxyglucose-positron emission tomography (PET) and standard computed tomography (CT) on definition of target volumes and toxicity parameters was evaluated, by comparison with standard CT-based simulation with and without ENI. CT-based gross tumor volume (GTVCT) was first contoured by a single observer without knowledge of PET results. Subsequently, the integrated GTV based on PET/CT coregistered images (GTVPET/CT) was defined. Each patient was planned according to three different treatment techniques: 1) radiotherapy with ENI using the CT data set alone (ENI plan); 2) radiotherapy without ENI using the CT data set alone (no ENI plan); 3) radiotherapy without ENI using PET/CT fusion data set (PET plan). Rival plans were compared for each patient with respect to dose to the normal tissues (spinal cord, healthy lungs, heart and esophagus). The addition of PET-modified TNM staging in 10/21 enrolled patients (48%); 3/21 were shifted to palliative treatment due to detection of metastatic disease or large tumor not amenable to high-dose radiotherapy. In 7/18 (39%) patients treated with radical radiotherapy, a significant (> or =25%) change in volume between GTVCT and GTVPET/CT was observed. For all the organs at risk, ENI plans had dose values significantly greater than no-ENI and PET plans. Comparing no ENI and PET plans, no statistically significant difference was observed, except for maximum point dose to the spinal cord Dmax, which was significantly lower in PET plans. Notably, even in patients in whom PET/CT planning resulted in an increased GTV, toxicity parameters were fairly acceptable, and always more favorable than with ENI plans. Our study suggests that [18F]-fluorodeoxyglucose-PET should be integrated in no-ENI techniques, as it improves target volume delineation without a major increase in predicted toxicity.

Improving the Diagnostic Specificity of CT for Early Detection of Lung Cancer: 4D CT-Based Pulmonary Nodule Elastometry

DTIC Science & Technology

2015-10-01

malignant PNs treated with stereotactic ablative radiotherapy ( SABR ) with those of the lung. Methods: We analyzed breath-hold images of 30...patients with malignant PNs who underwent SABR in our department. A parametric nonrigid transformation model based on multi-level B-spline guided by Sum of...and 50 of 4D CT and deep inhale and natural exhale of breath-hold CT images of 30 MPN treated with stereotactic ablative radiotherapy ( SABR ). The

SU-E-J-106: The Use of Deformable Image Registration with Cone-Beam CT for a Better Evaluation of Cumulative Dose to Organs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fillion, O; Gingras, L; Archambault, L

2015-06-15

Purpose: The knowledge of dose accumulation in the patient tissues in radiotherapy helps in determining the treatment outcomes. This project aims at providing a workflow to map cumulative doses that takes into account interfraction organ motion without the need for manual re-contouring. Methods: Five prostate cancer patients were studied. Each patient had a planning CT (pCT) and 5 to 13 CBCT scans. On each series, a physician contoured the prostate, rectum, bladder, seminal vesicles and the intestine. First, a deformable image registration (DIR) of the pCTs onto the daily CBCTs yielded registered CTs (rCT) . This rCT combined the accuratemore » CT numbers of the pCT with the daily anatomy of the CBCT. Second, the original plans (220 cGy per fraction for 25 fractions) were copied on the rCT for dose re-calculation. Third, the DIR software Elastix was used to find the inverse transform from the rCT to the pCT. This transformation was then applied to the rCT dose grid to map the dose voxels back to their pCT location. Finally, the sum of these deformed dose grids for each patient was applied on the pCT to calculate the actual dose delivered to organs. Results: The discrepancy between the planned D98 and D2 and these indices re-calculated on the rCT, are, on average, of −1 ± 1 cGy and 1 ± 2 cGy per fraction, respectively. For fractions with large anatomical motion, the D98 discrepancy on the re-calculated dose grid mapped onto the pCT can raise to −17 ± 4 cGy. The obtained cumulative dose distributions illustrate the same behavior. Conclusion: This approach allowed the evaluation of cumulative doses to organs with the help of uncontoured daily CBCT scans. With this workflow, the easy evaluation of doses delivered for EBRT treatments could ultimately lead to a better follow-up of prostate cancer patients.« less

An assessment of PTV margin based on actual accumulated dose for prostate cancer radiotherapy

NASA Astrophysics Data System (ADS)

Wen, Ning; Kumarasiri, Akila; Nurushev, Teamour; Burmeister, Jay; Xing, Lei; Liu, Dezhi; Glide-Hurst, Carri; Kim, Jinkoo; Zhong, Hualiang; Movsas, Benjamin; Chetty, Indrin J.

2013-11-01

The purpose of this work is to present the results of a margin reduction study involving dosimetric and radiobiologic assessment of cumulative dose distributions, computed using an image guided adaptive radiotherapy based framework. Eight prostate cancer patients, treated with 7-9, 6 MV, intensity modulated radiation therapy (IMRT) fields, were included in this study. The workflow consists of cone beam CT (CBCT) based localization, deformable image registration of the CBCT to simulation CT image datasets (SIM-CT), dose reconstruction and dose accumulation on the SIM-CT, and plan evaluation using radiobiological models. For each patient, three IMRT plans were generated with different margins applied to the CTV. The PTV margin for the original plan was 10 mm and 6 mm at the prostate/anterior rectal wall interface (10/6 mm) and was reduced to: (a) 5/3 mm, and (b) 3 mm uniformly. The average percent reductions in predicted tumor control probability (TCP) in the accumulated (actual) plans in comparison to the original plans over eight patients were 0.4%, 0.7% and 11.0% with 10/6 mm, 5/3 mm and 3 mm uniform margin respectively. The mean increase in predicted normal tissue complication probability (NTCP) for grades 2/3 rectal bleeding for the actual plans in comparison to the static plans with margins of 10/6, 5/3 and 3 mm uniformly was 3.5%, 2.8% and 2.4% respectively. For the actual dose distributions, predicted NTCP for late rectal bleeding was reduced by 3.6% on average when the margin was reduced from 10/6 mm to 5/3 mm, and further reduced by 1.0% on average when the margin was reduced to 3 mm. The average reduction in complication free tumor control probability (P+) in the actual plans in comparison to the original plans with margins of 10/6, 5/3 and 3 mm was 3.7%, 2.4% and 13.6% correspondingly. The significant reduction of TCP and P+ in the actual plan with 3 mm margin came from one outlier, where individualizing patient treatment plans through margin adaptation based on biological models, might yield higher quality treatments.

Radiotherapy volume delineation using 18F-FDG-PET/CT modifies gross node volume in patients with oesophageal cancer.

PubMed

Jimenez-Jimenez, E; Mateos, P; Aymar, N; Roncero, R; Ortiz, I; Gimenez, M; Pardo, J; Salinas, J; Sabater, S

2018-05-02

Evidence supporting the use of 18F-FDG-PET/CT in the segmentation process of oesophageal cancer for radiotherapy planning is limited. Our aim was to compare the volumes and tumour lengths defined by fused PET/CT vs. CT simulation. Twenty-nine patients were analyzed. All patients underwent a single PET/CT simulation scan. Two separate GTVs were defined: one based on CT data alone and another based on fused PET/CT data. Volume sizes for both data sets were compared and the spatial overlap was assessed by the Dice similarity coefficient (DSC). The gross tumour volume (GTVtumour) and maximum tumour diameter were greater by PET/CT, and length of primary tumour was greater by CT, but differences were not statistically significant. However, the gross node volume (GTVnode) was significantly greater by PET/CT. The DSC analysis showed excellent agreement for GTVtumour, 0.72, but was very low for GTVnode, 0.25. Our study shows that the volume definition by PET/CT and CT data differs. CT simulation, without taking into account PET/CT information, might leave cancer-involved nodes out of the radiotherapy-delineated volumes.

A clip-based protocol for breast boost radiotherapy provides clear target visualisation and demonstrates significant volume reduction over time

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lewis, Lorraine; Cox, Jennifer; Faculty of Health Sciences, University of Sydney, Sydney, New South Wales

2015-09-15

The clinical target volume (CTV) for early stage breast cancer is difficult to clearly identify on planning computed tomography (CT) scans. Surgical clips inserted around the tumour bed should help to identify the CTV, particularly if the seroma has been reabsorbed, and enable tracking of CTV changes over time. A surgical clip-based CTV delineation protocol was introduced. CTV visibility and its post-operative shrinkage pattern were assessed. The subjects were 27 early stage breast cancer patients receiving post-operative radiotherapy alone and 15 receiving post-operative chemotherapy followed by radiotherapy. The radiotherapy alone (RT/alone) group received a CT scan at median 25 daysmore » post-operatively (CT1rt) and another at 40 Gy, median 68 days (CT2rt). The chemotherapy/RT group (chemo/RT) received a CT scan at median 18 days post-operatively (CT1ch), a planning CT scan at median 126 days (CT2ch), and another at 40 Gy (CT3ch). There was no significant difference (P = 0.08) between the initial mean CTV for each cohort. The RT/alone cohort showed significant CTV volume reduction of 38.4% (P = 0.01) at 40 Gy. The Chemo/RT cohort had significantly reduced volumes between CT1ch: median 54 cm{sup 3} (4–118) and CT2ch: median 16 cm{sup 3}, (2–99), (P = 0.01), but no significant volume reduction thereafter. Surgical clips enable localisation of the post-surgical seroma for radiotherapy targeting. Most seroma shrinkage occurs early, enabling CT treatment planning to take place at 7 weeks, which is within the 9 weeks recommended to limit disease recurrence.« less

Phantom-less bone mineral density (BMD) measurement using dual energy computed tomography-based 3-material decomposition

NASA Astrophysics Data System (ADS)

Hofmann, Philipp; Sedlmair, Martin; Krauss, Bernhard; Wichmann, Julian L.; Bauer, Ralf W.; Flohr, Thomas G.; Mahnken, Andreas H.

2016-03-01

Osteoporosis is a degenerative bone disease usually diagnosed at the manifestation of fragility fractures, which severely endanger the health of especially the elderly. To ensure timely therapeutic countermeasures, noninvasive and widely applicable diagnostic methods are required. Currently the primary quantifiable indicator for bone stability, bone mineral density (BMD), is obtained either by DEXA (Dual-energy X-ray absorptiometry) or qCT (quantitative CT). Both have respective advantages and disadvantages, with DEXA being considered as gold standard. For timely diagnosis of osteoporosis, another CT-based method is presented. A Dual Energy CT reconstruction workflow is being developed to evaluate BMD by evaluating lumbar spine (L1-L4) DE-CT images. The workflow is ROI-based and automated for practical use. A dual energy 3-material decomposition algorithm is used to differentiate bone from soft tissue and fat attenuation. The algorithm uses material attenuation coefficients on different beam energy levels. The bone fraction of the three different tissues is used to calculate the amount of hydroxylapatite in the trabecular bone of the corpus vertebrae inside a predefined ROI. Calibrations have been performed to obtain volumetric bone mineral density (vBMD) without having to add a calibration phantom or to use special scan protocols or hardware. Accuracy and precision are dependent on image noise and comparable to qCT images. Clinical indications are in accordance with the DEXA gold standard. The decomposition-based workflow shows bone degradation effects normally not visible on standard CT images which would induce errors in normal qCT results.

Uncertainties in estimating heart doses from 2D-tangential breast cancer radiotherapy.

PubMed

Lorenzen, Ebbe L; Brink, Carsten; Taylor, Carolyn W; Darby, Sarah C; Ewertz, Marianne

2016-04-01

We evaluated the accuracy of three methods of estimating radiation dose to the heart from two-dimensional tangential radiotherapy for breast cancer, as used in Denmark during 1982-2002. Three tangential radiotherapy regimens were reconstructed using CT-based planning scans for 40 patients with left-sided and 10 with right-sided breast cancer. Setup errors and organ motion were simulated using estimated uncertainties. For left-sided patients, mean heart dose was related to maximum heart distance in the medial field. For left-sided breast cancer, mean heart dose estimated from individual CT-scans varied from <1Gy to >8Gy, and maximum dose from 5 to 50Gy for all three regimens, so that estimates based only on regimen had substantial uncertainty. When maximum heart distance was taken into account, the uncertainty was reduced and was comparable to the uncertainty of estimates based on individual CT-scans. For right-sided breast cancer patients, mean heart dose based on individual CT-scans was always <1Gy and maximum dose always <5Gy for all three regimens. The use of stored individual simulator films provides a method for estimating heart doses in left-tangential radiotherapy for breast cancer that is almost as accurate as estimates based on individual CT-scans. Copyright © 2016. Published by Elsevier Ireland Ltd.

SU-F-J-110: MRI-Guided Single-Session Simulation, Online Adaptation, and Treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hill, P; Geurts, M; Mittauer, K

Purpose: To develop a combined simulation and treatment workflow for MRI-guided radiation therapy using the ViewRay treatment planning and delivery system. Methods: Several features of the ViewRay MRIdian planning and treatment workflows are used to simulate and treat patients that require emergent radiotherapy. A simple “pre-plan” is created on diagnostic imaging retrieved from radiology PACS, where conformal fields are created to target a volume defined by a physician based on review of the diagnostic images and chart notes. After initial consult in radiation oncology, the patient is brought to the treatment room, immobilized, and imaged in treatment position with amore » volumetric MR. While the patient rests on the table, the pre-plan is applied to the treatment planning MR and dose is calculated in the treatment geometry. After physician review, modification of the plan may include updating the target definition, redefining fields, or re-balancing beam weights. Once an acceptable treatment plan is finalized and approved, the patient is treated. Results: Careful preparation and judicious choices in the online planning process allow conformal treatment plans to be created and delivered in a single, thirty-minute session. Several advantages have been identified using this process as compared to conventional urgent CT simulation and delivery. Efficiency gains are notable, as physicians appreciate the predictable time commitment and patient waiting time for treatment is decreased. MR guidance in a treatment position offers both enhanced contrast for target delineation and reduction of setup uncertainties. The MRIdian system tools designed for adaptive radiotherapy are particularly useful, enabling plan changes to be made in minutes. Finally, the resulting plans, typically 6 conformal beams, are delivered as quickly as more conventional AP/PA beam arrangements with comparatively superior dose distributions. Conclusion: The ViewRay treatment planning software and delivery system can accommodate a fast simulation and treatment workflow.« less

TH-CD-206-09: Learning-Based MRI-CT Prostate Registration Using Spare Patch-Deformation Dictionary

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, X; Jani, A; Rossi, P

Purpose: To enable MRI-guided prostate radiotherapy, MRI-CT deformable registration is required to map the MRI-defined tumor and key organ contours onto the CT images. Due to the intrinsic differences in grey-level intensity characteristics between MRI and CT images, the integration of MRI into CT-based radiotherapy is very challenging. We are developing a learning-based registration approach to address this technical challenge. Methods: We propose to estimate the deformation between MRI and CT images in a patch-wise fashion by using the sparse representation technique. Specifically, we assume that two image patches should follow the same deformation if their patch-wise appearance patterns aremore » similar. We first extract a set of key points in the new CT image. Then, for each key point, we adaptively construct a coupled dictionary from the training MRI-CT images, where each coupled element includes both appearance and deformation of the same image patch. After calculating the sparse coefficients in representing the patch appearance of each key point based on the constructed dictionary, we can predict the deformation for this point by applying the same sparse coefficients to the respective deformations in the dictionary. Results: This registration technique was validated with 10 prostate-cancer patients’ data and its performance was compared with the commonly used free-form-deformation-based registration. Several landmarks in both images were identified to evaluate the accuracy of our approach. Overall, the averaged target registration error of the intensity-based registration and the proposed method was 3.8±0.4 mm and 1.9±0.3 mm, respectively. Conclusion: We have developed a novel prostate MR-CT registration approach based on patch-deformation dictionary, demonstrated its clinical feasibility, and validated its accuracy. This technique will either reduce or compensate for the effect of patient-specific treatment variation measured during the course of radiotherapy, is therefore well-suited for a number of MRI-guided adaptive radiotherapy, and potentially enhance prostate radiotherapy treatment outcome.« less

First Clinical Investigation of Cone Beam Computed Tomography and Deformable Registration for Adaptive Proton Therapy for Lung Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veiga, Catarina; Janssens, Guillaume; Teng, Ching-Ling

2016-05-01

Purpose: An adaptive proton therapy workflow using cone beam computed tomography (CBCT) is proposed. It consists of an online evaluation of a fast range-corrected dose distribution based on a virtual CT (vCT) scan. This can be followed by more accurate offline dose recalculation on the vCT scan, which can trigger a rescan CT (rCT) for replanning. Methods and Materials: The workflow was tested retrospectively for 20 consecutive lung cancer patients. A diffeomorphic Morphon algorithm was used to generate the lung vCT by deforming the average planning CT onto the CBCT scan. An additional correction step was applied to account formore » anatomic modifications that cannot be modeled by deformation alone. A set of clinical indicators for replanning were generated according to the water equivalent thickness (WET) and dose statistics and compared with those obtained on the rCT scan. The fast dose approximation consisted of warping the initial planned dose onto the vCT scan according to the changes in WET. The potential under- and over-ranges were assessed as a variation in WET at the target's distal surface. Results: The range-corrected dose from the vCT scan reproduced clinical indicators similar to those of the rCT scan. The workflow performed well under different clinical scenarios, including atelectasis, lung reinflation, and different types of tumor response. Between the vCT and rCT scans, we found a difference in the measured 95% percentile of the over-range distribution of 3.4 ± 2.7 mm. The limitations of the technique consisted of inherent uncertainties in deformable registration and the drawbacks of CBCT imaging. The correction step was adequate when gross errors occurred but could not recover subtle anatomic or density changes in tumors with complex topology. Conclusions: A proton therapy workflow based on CBCT provided clinical indicators similar to those using rCT for patients with lung cancer with considerable anatomic changes.« less

MR-based synthetic CT generation using a deep convolutional neural network method.

PubMed

Han, Xiao

2017-04-01

Interests have been rapidly growing in the field of radiotherapy to replace CT with magnetic resonance imaging (MRI), due to superior soft tissue contrast offered by MRI and the desire to reduce unnecessary radiation dose. MR-only radiotherapy also simplifies clinical workflow and avoids uncertainties in aligning MR with CT. Methods, however, are needed to derive CT-equivalent representations, often known as synthetic CT (sCT), from patient MR images for dose calculation and DRR-based patient positioning. Synthetic CT estimation is also important for PET attenuation correction in hybrid PET-MR systems. We propose in this work a novel deep convolutional neural network (DCNN) method for sCT generation and evaluate its performance on a set of brain tumor patient images. The proposed method builds upon recent developments of deep learning and convolutional neural networks in the computer vision literature. The proposed DCNN model has 27 convolutional layers interleaved with pooling and unpooling layers and 35 million free parameters, which can be trained to learn a direct end-to-end mapping from MR images to their corresponding CTs. Training such a large model on our limited data is made possible through the principle of transfer learning and by initializing model weights from a pretrained model. Eighteen brain tumor patients with both CT and T1-weighted MR images are used as experimental data and a sixfold cross-validation study is performed. Each sCT generated is compared against the real CT image of the same patient on a voxel-by-voxel basis. Comparison is also made with respect to an atlas-based approach that involves deformable atlas registration and patch-based atlas fusion. The proposed DCNN method produced a mean absolute error (MAE) below 85 HU for 13 of the 18 test subjects. The overall average MAE was 84.8 ± 17.3 HU for all subjects, which was found to be significantly better than the average MAE of 94.5 ± 17.8 HU for the atlas-based method. The DCNN method also provided significantly better accuracy when being evaluated using two other metrics: the mean squared error (188.6 ± 33.7 versus 198.3 ± 33.0) and the Pearson correlation coefficient(0.906 ± 0.03 versus 0.896 ± 0.03). Although training a DCNN model can be slow, training only need be done once. Applying a trained model to generate a complete sCT volume for each new patient MR image only took 9 s, which was much faster than the atlas-based approach. A DCNN model method was developed, and shown to be able to produce highly accurate sCT estimations from conventional, single-sequence MR images in near real time. Quantitative results also showed that the proposed method competed favorably with an atlas-based method, in terms of both accuracy and computation speed at test time. Further validation on dose computation accuracy and on a larger patient cohort is warranted. Extensions of the method are also possible to further improve accuracy or to handle multi-sequence MR images. © 2017 American Association of Physicists in Medicine.

An automatic dose verification system for adaptive radiotherapy for helical tomotherapy

NASA Astrophysics Data System (ADS)

Mo, Xiaohu; Chen, Mingli; Parnell, Donald; Olivera, Gustavo; Galmarini, Daniel; Lu, Weiguo

2014-03-01

Purpose: During a typical 5-7 week treatment of external beam radiotherapy, there are potential differences between planned patient's anatomy and positioning, such as patient weight loss, or treatment setup. The discrepancies between planned and delivered doses resulting from these differences could be significant, especially in IMRT where dose distributions tightly conforms to target volumes while avoiding organs-at-risk. We developed an automatic system to monitor delivered dose using daily imaging. Methods: For each treatment, a merged image is generated by registering the daily pre-treatment setup image and planning CT using treatment position information extracted from the Tomotherapy archive. The treatment dose is then computed on this merged image using our in-house convolution-superposition based dose calculator implemented on GPU. The deformation field between merged and planning CT is computed using the Morphon algorithm. The planning structures and treatment doses are subsequently warped for analysis and dose accumulation. All results are saved in DICOM format with private tags and organized in a database. Due to the overwhelming amount of information generated, a customizable tolerance system is used to flag potential treatment errors or significant anatomical changes. A web-based system and a DICOM-RT viewer were developed for reporting and reviewing the results. Results: More than 30 patients were analysed retrospectively. Our in-house dose calculator passed 97% gamma test evaluated with 2% dose difference and 2mm distance-to-agreement compared with Tomotherapy calculated dose, which is considered sufficient for adaptive radiotherapy purposes. Evaluation of the deformable registration through visual inspection showed acceptable and consistent results, except for cases with large or unrealistic deformation. Our automatic flagging system was able to catch significant patient setup errors or anatomical changes. Conclusions: We developed an automatic dose verification system that quantifies treatment doses, and provides necessary information for adaptive planning without impeding clinical workflows.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yeung, Timothy P C; Robarts Research Institute, The University of Western Ontario, Ontario, Canada, N6A 5B7; Department of Medical Biophysics, The University of Western Ontario, Ontario, Canada, N6A 5C1

Introduction: This study aimed to explore the potential for computed tomography (CT) perfusion and 18-Fluorodeoxyglucose positron emission tomography (FDG-PET) in predicting sites of future progressive tumour on a voxel-by-voxel basis after radiotherapy and chemotherapy. Methods: Ten patients underwent pre-radiotherapy magnetic resonance (MR), FDG-PET and CT perfusion near the end of radiotherapy and repeated post-radiotherapy follow-up MR scans. The relationships between these images and tumour progression were assessed using logistic regression. Cross-validation with receiver operating characteristic (ROC) analysis was used to assess the value of these images in predicting sites of tumour progression. Results: Pre-radiotherapy MR-defined gross tumour; near-end-of-radiotherapy CT-defined enhancingmore » lesion; CT perfusion blood flow (BF), blood volume (BV) and permeability-surface area (PS) product; FDG-PET standard uptake value (SUV); and SUV:BF showed significant associations with tumour progression on follow-up MR imaging (P < 0.0001). The mean sensitivity (±standard deviation), specificity and area under the ROC curve (AUC) of PS were 0.64 ± 0.15, 0.74 ± 0.07 and 0.72 ± 0.12 respectively. This mean AUC was higher than that of the pre-radiotherapy MR-defined gross tumour and near-end-of-radiotherapy CT-defined enhancing lesion (both AUCs = 0.6 ± 0.1, P ≤ 0.03). The multivariate model using BF, BV, PS and SUV had a mean AUC of 0.8 ± 0.1, but this was not significantly higher than the PS only model. Conclusion: PS is the single best predictor of tumour progression when compared to other parameters, but voxel-based prediction based on logistic regression had modest sensitivity and specificity.« less

Designing the safety of healthcare. Participation of ergonomics to the design of cooperative systems in radiotherapy.

PubMed

Munoz, Maria Isabel; Bouldi, Nadia; Barcellini, Flore; Nascimento, Adelaide

2012-01-01

This communication deals with the involvement of ergonomists in a research-action design process of a software platform in radiotherapy. The goal of the design project is to enhance patient safety by designing a workflow software that supports cooperation between professionals producing treatment in radiotherapy. The general framework of our approach is the ergonomics management of a design process, which is based in activity analysis and grounded in participatory design. Two fields are concerned by the present action: a design environment which is a participatory design process that involves software designers, caregivers as future users and ergonomists; and a reference real work setting in radiotherapy. Observations, semi-structured interviews and participatory workshops allow the characterization of activity in radiotherapy dealing with uses of cooperative tools, sources of variability and non-ruled strategies to manage the variability of the situations. This production of knowledge about work searches to enhance the articulation between technocentric and anthropocentric approaches, and helps in clarifying design requirements. An issue of this research-action is to develop a framework to define the parameters of the workflow tool, and the conditions of its deployment.

Incremental Learning With Selective Memory (ILSM): Towards Fast Prostate Localization for Image Guided Radiotherapy

PubMed Central

Gao, Yaozong; Zhan, Yiqiang

2015-01-01

Image-guided radiotherapy (IGRT) requires fast and accurate localization of the prostate in 3-D treatment-guided radiotherapy, which is challenging due to low tissue contrast and large anatomical variation across patients. On the other hand, the IGRT workflow involves collecting a series of computed tomography (CT) images from the same patient under treatment. These images contain valuable patient-specific information yet are often neglected by previous works. In this paper, we propose a novel learning framework, namely incremental learning with selective memory (ILSM), to effectively learn the patient-specific appearance characteristics from these patient-specific images. Specifically, starting with a population-based discriminative appearance model, ILSM aims to “personalize” the model to fit patient-specific appearance characteristics. The model is personalized with two steps: backward pruning that discards obsolete population-based knowledge and forward learning that incorporates patient-specific characteristics. By effectively combining the patient-specific characteristics with the general population statistics, the incrementally learned appearance model can localize the prostate of a specific patient much more accurately. This work has three contributions: 1) the proposed incremental learning framework can capture patient-specific characteristics more effectively, compared to traditional learning schemes, such as pure patient-specific learning, population-based learning, and mixture learning with patient-specific and population data; 2) this learning framework does not have any parametric model assumption, hence, allowing the adoption of any discriminative classifier; and 3) using ILSM, we can localize the prostate in treatment CTs accurately (DSC ∼0.89) and fast (∼4 s), which satisfies the real-world clinical requirements of IGRT. PMID:24495983

Clinical implementation of 3D printing in the construction of patient specific bolus for electron beam radiotherapy for non-melanoma skin cancer.

PubMed

Canters, Richard A; Lips, Irene M; Wendling, Markus; Kusters, Martijn; van Zeeland, Marianne; Gerritsen, Rianne M; Poortmans, Philip; Verhoef, Cornelia G

2016-10-01

Creating an individualized tissue equivalent material build-up (i.e. bolus) for electron beam radiation therapy is complex and highly labour-intensive. We implemented a new clinical workflow in which 3D printing technology is used to create the bolus. A patient-specific bolus is designed in the treatment planning system (TPS) and a shell around it is created in the TPS. The shell is printed and subsequently filled with silicone rubber to make the bolus. Before clinical implementation we performed a planning study with 11 patients to evaluate the difference in tumour coverage between the designed 3D-print bolus and the clinically delivered plan with manually created bolus. For the first 15 clinical patients a second CT scan with the 3D-print bolus was performed to verify the geometrical accuracy. The planning study showed that the V85% of the CTV was on average 97% (3D-print) vs 88% (conventional). Geometric comparison of the 3D-print bolus to the originally contoured bolus showed a high similarity (DSC=0.89). The dose distributions on the second CT scan with the 3D print bolus in position showed only small differences in comparison to the original planning CT scan. The implemented workflow is feasible, patient friendly, safe, and results in high quality dose distributions. This new technique increases time efficiency. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Prospective feasibility trial of radiotherapy target definition for head and neck cancer using 3-dimensional PET and CT imaging.

PubMed

Scarfone, Christopher; Lavely, William C; Cmelak, Anthony J; Delbeke, Dominique; Martin, William H; Billheimer, Dean; Hallahan, Dennis E

2004-04-01

The aim of this investigation was to evaluate the influence and accuracy of (18)F-FDG PET in target volume definition as a complementary modality to CT for patients with head and neck cancer (HNC) using dedicated PET and CT scanners. Six HNC patients were custom fitted with head and neck and upper body immobilization devices, and conventional radiotherapy CT simulation was performed together with (18)F-FDG PET imaging. Gross target volume (GTV) and pathologic nodal volumes were first defined in the conventional manner based on CT. A segmentation and surface-rendering registration technique was then used to coregister the (18)F-FDG PET and CT planning image datasets. (18)F-FDG PET GTVs were determined and displayed simultaneously with the CT contours. CT GTVs were then modified based on the PET data to form final PET/CT treatment volumes. Five-field intensity-modulated radiation therapy (IMRT) was then used to demonstrate dose targeting to the CT GTV or the PET/CT GTV. One patient was PET-negative after induction chemotherapy. The CT GTV was modified in all remaining patients based on (18)F-FDG PET data. The resulting PET/CT GTV was larger than the original CT volume by an average of 15%. In 5 cases, (18)F-FDG PET identified active lymph nodes that corresponded to lymph nodes contoured on CT. The pathologically enlarged CT lymph nodes were modified to create final lymph node volumes in 3 of 5 cases. In 1 of 6 patients, (18)F-FDG-avid lymph nodes were not identified as pathologic on CT. In 2 of 6 patients, registration of the independently acquired PET and CT data using segmentation and surface rendering resulted in a suboptimal alignment and, therefore, had to be repeated. Radiotherapy planning using IMRT demonstrated the capability of this technique to target anatomic or anatomic/physiologic target volumes. In this manner, metabolically active sites can be intensified to greater daily doses. Inclusion of (18)F-FDG PET data resulted in modified target volumes in radiotherapy planning for HNC. PET and CT data acquired on separate, dedicated scanners may be coregistered for therapy planning; however, dual-acquisition PET/CT systems may be considered to reduce the need for reregistrations. It is possible to use IMRT to target dose to metabolically active sites based on coregistered PET/CT data.

SU-F-E-10: Student-Driven Exploration of Radiographic Material Properties, Phantom Construction, and Clinical Workflows Or: The Extraordinary Life of CANDY MAN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahon, RN; Riblett, MJ; Hugo, GD

Purpose: To develop a hands-on learning experience that explores the radiological and structural properties of everyday items and applies this knowledge to design a simple phantom for radiotherapy exercises. Methods: Students were asked to compile a list of readily available materials thought to have radiation attenuation properties similar to tissues within the human torso. Participants scanned samples of suggested materials and regions of interest (ROIs) were used to characterize bulk attenuation properties. Properties of each material were assessed via comparison to a Gammex Tissue characterization phantom and used to construct a list of inexpensive near-tissue-equivalent materials. Critical discussions focusing onmore » samples found to differ from student expectations were used to revise and narrow the comprehensive list. From their newly acquired knowledge, students designed and constructed a simple thoracic phantom for use in a simulated clinical workflow. Students were tasked with setting up the phantom and acquiring planning CT images for use in treatment planning and dose delivery. Results: Under engineer and physicist supervision, students were trained to use a CT simulator and acquired images for approximately 60 different foodstuffs, candies, and household items. Through peer discussion, students gained valuable insights and were made to review preconceptions about radiographic material properties. From a subset of imaged materials, a simple phantom was successfully designed and constructed to represent a human thorax. Students received hands-on experience with clinical treatment workflows by learning how to perform CT simulation, create a treatment plan for an embedded tumor, align the phantom for treatment, and deliver a treatment fraction. Conclusion: In this activity, students demonstrated their ability to reason through the radiographic material selection process, construct a simple phantom to specifications, and exercise their knowledge of clinical workflows. Furthermore, the enjoyable and inexpensive nature of this project proved to attract participant interest and drive creative exploration. Mahon and Riblett have nothing to disclose; Hugo has a research agreement with Phillips Medical systems, a license agreement with Varian Medical Systems, research grants from the National Institute of Health. Authors do not have any potential conflicts of interest to disclose.« less

Simulation of spatiotemporal CT data sets using a 4D MRI-based lung motion model.

PubMed

Marx, Mirko; Ehrhardt, Jan; Werner, René; Schlemmer, Heinz-Peter; Handels, Heinz

2014-05-01

Four-dimensional CT imaging is widely used to account for motion-related effects during radiotherapy planning of lung cancer patients. However, 4D CT often contains motion artifacts, cannot be used to measure motion variability, and leads to higher dose exposure. In this article, we propose using 4D MRI to acquire motion information for the radiotherapy planning process. From the 4D MRI images, we derive a time-continuous model of the average patient-specific respiratory motion, which is then applied to simulate 4D CT data based on a static 3D CT. The idea of the motion model is to represent the average lung motion over a respiratory cycle by cyclic B-spline curves. The model generation consists of motion field estimation in the 4D MRI data by nonlinear registration, assigning respiratory phases to the motion fields, and applying a B-spline approximation on a voxel-by-voxel basis to describe the average voxel motion over a breathing cycle. To simulate a patient-specific 4D CT based on a static CT of the patient, a multi-modal registration strategy is introduced to transfer the motion model from MRI to the static CT coordinates. Differences between model-based estimated and measured motion vectors are on average 1.39 mm for amplitude-based binning of the 4D MRI data of three patients. In addition, the MRI-to-CT registration strategy is shown to be suitable for the model transformation. The application of our 4D MRI-based motion model for simulating 4D CT images provides advantages over standard 4D CT (less motion artifacts, radiation-free). This makes it interesting for radiotherapy planning.

SU-G-JeP2-06: Dosimetric and Workflow Evaluation of First Commercial Synthetic CT Software for Clinical Use in Pelvis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tyagi, N; Zhang, J; Happersett, L

2016-06-15

Purpose: evaluate a commercial synthetic CT (syn-CT) software for use in prostate radiotherapy Methods: Twenty prostate patients underwent CT and MR simulation scans in treatment position on a 3T Philips scanner. The MR protocol consisted of a T2w turbo spin-echo for soft tissue contrast, a 2D balanced-fast field echo (b-FFE) for fiducial identification, a dual-echo 3D FFE B0 map for distortion analysis and a 3D mDIXON FFE sequence to generate syn-CT. Two echoes are acquired during mDIXON scan, allowing water, fat, and in-phase images to be derived using the frequency shift of the fat and water protons. Tissues were classifiedmore » as: air, adipose, water, trabecular/spongy bone and compact/cortical bone and assigned specific bulk HU values. Bone structures are segmented based on a pelvis bone atlas. Accuracy of syn-CT for patient treatment planning was analyzed by transferring the original plan and structures from the CT to syn-CT via rigid registration and recalculating dose. In addition, new IMRT plans were generated on the syn-CT using structures contoured on MR and transferred to the syn-CT. Accuracy of fiducial-based localization at the treatment machine performed using syn-CT or DRRs generated from syn-CT was assessed by comparing to orthogonal kV radiographs or CBCT. Results: Dosimetric comparison between CT and syn-CT was within 0.5% for all structures. The de-novo optimized plans generated on the syn-CT met our institutional clinical objectives for target and normal structures. Patient-induced susceptibility distortion based on B0 maps was within 1mm and 0.4 mm in the body and prostate. The rectal and bladder outlines on the syn-CT were deemed sufficient for assessing rectal and bladder filling on the CBCT at the time of treatment. CBCT localization showed a median error of < ±1 mm in LR, AP and SI direction. Conclusion: MRI derived syn-CT can be used clinically in MR-alone planning and treatment process for prostate. Drs. Deasy, Hunt and Tyagi have Master research agreement with Philips healthcare.« less

Generation of synthetic CT using multi-scale and dual-contrast patches for brain MRI-only external beam radiotherapy.

PubMed

Aouadi, Souha; Vasic, Ana; Paloor, Satheesh; Torfeh, Tarraf; McGarry, Maeve; Petric, Primoz; Riyas, Mohamed; Hammoud, Rabih; Al-Hammadi, Noora

2017-10-01

To create a synthetic CT (sCT) from conventional brain MRI using a patch-based method for MRI-only radiotherapy planning and verification. Conventional T1 and T2-weighted MRI and CT datasets from 13 patients who underwent brain radiotherapy were included in a retrospective study whereas 6 patients were tested prospectively. A new contribution to the Non-local Means Patch-Based Method (NMPBM) framework was done with the use of novel multi-scale and dual-contrast patches. Furthermore, the training dataset was improved by pre-selecting the closest database patients to the target patient for computation time/accuracy balance. sCT and derived DRRs were assessed visually and quantitatively. VMAT planning was performed on CT and sCT for hypothetical PTVs in homogeneous and heterogeneous regions. Dosimetric analysis was done by comparing Dose Volume Histogram (DVH) parameters of PTVs and organs at risk (OARs). Positional accuracy of MRI-only image-guided radiation therapy based on CBCT or kV images was evaluated. The retrospective (respectively prospective) evaluation of the proposed Multi-scale and Dual-contrast Patch-Based Method (MDPBM) gave a mean absolute error MAE=99.69±11.07HU (98.95±8.35HU), and a Dice in bones DI bone =83±0.03 (0.82±0.03). Good agreement with conventional planning techniques was obtained; the highest percentage of DVH metric deviations was 0.43% (0.53%) for PTVs and 0.59% (0.75%) for OARs. The accuracy of sCT/CBCT or DRR sCT /kV images registration parameters was <2mm and <2°. Improvements with MDPBM, compared to NMPBM, were significant. We presented a novel method for sCT generation from T1 and T2-weighted MRI potentially suitable for MRI-only external beam radiotherapy in brain sites. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Safety and feasibility of STAT RAD: Improvement of a novel rapid tomotherapy-based radiation therapy workflow by failure mode and effects analysis.

PubMed

Jones, Ryan T; Handsfield, Lydia; Read, Paul W; Wilson, David D; Van Ausdal, Ray; Schlesinger, David J; Siebers, Jeffrey V; Chen, Quan

2015-01-01

The clinical challenge of radiation therapy (RT) for painful bone metastases requires clinicians to consider both treatment efficacy and patient prognosis when selecting a radiation therapy regimen. The traditional RT workflow requires several weeks for common palliative RT schedules of 30 Gy in 10 fractions or 20 Gy in 5 fractions. At our institution, we have created a new RT workflow termed "STAT RAD" that allows clinicians to perform computed tomographic (CT) simulation, planning, and highly conformal single fraction treatment delivery within 2 hours. In this study, we evaluate the safety and feasibility of the STAT RAD workflow. A failure mode and effects analysis (FMEA) was performed on the STAT RAD workflow, including development of a process map, identification of potential failure modes, description of the cause and effect, temporal occurrence, and team member involvement in each failure mode, and examination of existing safety controls. A risk probability number (RPN) was calculated for each failure mode. As necessary, workflow adjustments were then made to safeguard failure modes of significant RPN values. After workflow alterations, RPN numbers were again recomputed. A total of 72 potential failure modes were identified in the pre-FMEA STAT RAD workflow, of which 22 met the RPN threshold for clinical significance. Workflow adjustments included the addition of a team member checklist, changing simulation from megavoltage CT to kilovoltage CT, alteration of patient-specific quality assurance testing, and allocating increased time for critical workflow steps. After these modifications, only 1 failure mode maintained RPN significance; patient motion after alignment or during treatment. Performing the FMEA for the STAT RAD workflow before clinical implementation has significantly strengthened the safety and feasibility of STAT RAD. The FMEA proved a valuable evaluation tool, identifying potential problem areas so that we could create a safer workflow. Copyright © 2015 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.

Influence of (11)C-choline PET/CT on radiotherapy planning in prostate cancer.

PubMed

López, Escarlata; Lazo, Antonio; Gutiérrez, Antonio; Arregui, Gregorio; Núñez, Isabel; Sacchetti, Antonio

2015-01-01

To evaluate the influence of (11)C-choline PET/CT on radiotherapy planning in prostate cancer patients. Precise information on the extension of prostate cancer is crucial for the choice of an appropriate therapeutic strategy. (11)C-choline positron emission tomography ((11)C-choline PET/CT) has two roles in radiation oncology (RT): (1) patient selection for treatment and (2) target volume selection and delineation. In conjunction with high-accuracy techniques, it might offer an opportunity of dose escalation and better tumour control while sparing healthy tissues. We carried out a retrospective study in order to analyse RT planning modification based on (11)C-choline PET/CT in 16 prostate cancer patients. Patients were treated with hypofractionated step-and-shoot Intensity Modulated Radiotherapy (IMRT), or Volumetric Modulated Arc Therapy (VMAT), and a daily cone-beam CT for Image Guided Radiation Therapy (IGRT). All patients underwent a (11)C-choline-PET/CT scan prior to radiotherapy. In 37.5% of cases, a re-delineation and new dose prescription occurred. Data show good preliminary clinical results in terms of biochemical control and toxicity. No gastrointestinal (GI)/genitourinary (GU) grade III toxicities were observed after a median follow-up of 9.5 months. In our experience, concerning the treatment of prostate cancer (PCa), (11)C-choline PET/CT may be helpful in radiotherapy planning, either for dose escalation or exclusion of selected sites.

Conventional 3D staging PET/CT in CT simulation for lung cancer: impact of rigid and deformable target volume alignments for radiotherapy treatment planning.

PubMed

Hanna, G G; Van Sörnsen De Koste, J R; Carson, K J; O'Sullivan, J M; Hounsell, A R; Senan, S

2011-10-01

Positron emission tomography (PET)/CT scans can improve target definition in radiotherapy for non-small cell lung cancer (NSCLC). As staging PET/CT scans are increasingly available, we evaluated different methods for co-registration of staging PET/CT data to radiotherapy simulation (RTP) scans. 10 patients underwent staging PET/CT followed by RTP PET/CT. On both scans, gross tumour volumes (GTVs) were delineated using CT (GTV(CT)) and PET display settings. Four PET-based contours (manual delineation, two threshold methods and a source-to-background ratio method) were delineated. The CT component of the staging scan was co-registered using both rigid and deformable techniques to the CT component of RTP PET/CT. Subsequently rigid registration and deformation warps were used to transfer PET and CT contours from the staging scan to the RTP scan. Dice's similarity coefficient (DSC) was used to assess the registration accuracy of staging-based GTVs following both registration methods with the GTVs delineated on the RTP PET/CT scan. When the GTV(CT) delineated on the staging scan after both rigid registration and deformation was compared with the GTV(CT)on the RTP scan, a significant improvement in overlap (registration) using deformation was observed (mean DSC 0.66 for rigid registration and 0.82 for deformable registration, p = 0.008). A similar comparison for PET contours revealed no significant improvement in overlap with the use of deformable registration. No consistent improvements in similarity measures were observed when deformable registration was used for transferring PET-based contours from a staging PET/CT. This suggests that currently the use of rigid registration remains the most appropriate method for RTP in NSCLC.

Specific recommendations for accurate and direct use of PET-CT in PET guided radiotherapy for head and neck sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, C. M., E-mail: christopher.thomas@gstt.nhs.uk; Convery, D. J.; Greener, A. G.

2014-04-15

Purpose: To provide specific experience-based guidance and recommendations for centers wishing to develop, validate, and implement an accurate and efficient process for directly using positron emission tomography-computed tomography (PET-CT) for the radiotherapy planning of head and neck cancer patients. Methods: A PET-CT system was modified with hard-top couch, external lasers and radiotherapy immobilization and indexing devices and was subject to a commissioning and quality assurance program. PET-CT imaging protocols were developed specifically for radiotherapy planning and the image quality and pathway tested using phantoms and five patients recruited into an in-house study. Security and accuracy of data transfer was testedmore » throughout the whole data pathway. The patient pathway was fully established and tested ready for implementation in a PET-guided dose-escalation trial for head and neck cancer patients. Results: Couch deflection was greater than for departmental CT simulator machines. An area of high attenuation in the couch generated image artifacts and adjustments were made accordingly. Using newly developed protocols CT image quality was suitable to maintain delineation and treatment accuracy. Upon transfer of data to the treatment planning system a half pixel offset between PET and CT was observed and corrected. By taking this into account, PET to CT alignment accuracy was maintained below 1 mm in all systems in the data pathway. Transfer of structures delineated in the PET fusion software to the radiotherapy treatment planning system was validated. Conclusions: A method to perform direct PET-guided radiotherapy planning was successfully validated and specific recommendations were developed to assist other centers. Of major concern is ensuring that the quality of PET and CT data is appropriate for radiotherapy treatment planning and on-treatment verification. Couch movements can be compromised, bore-size can be a limitation for certain immobilization techniques, laser positioning may affect setup accuracy and couch deflection may be greater than scanners dedicated to radiotherapy. The full set of departmental commissioning and routine quality assurance tests applied to radiotherapy CT simulators must be carried out on the PET-CT scanner. CT image quality must be optimized for radiotherapy planning whilst understanding that the appearance will differ between scanners and may affect delineation. PET-CT quality assurance schedules will need to be added to and modified to incorporate radiotherapy quality assurance. Methods of working for radiotherapy and PET staff will change to take into account considerations of both parties. PET to CT alignment must be subject to quality control on a loaded and unloaded couch preferably using a suitable emission phantom, and tested throughout the whole data pathway. Data integrity must be tested throughout the whole pathway and a system included to verify that delineated structures are transferred correctly. Excellent multidisciplinary team communication and working is vital, and key staff members on both sides should be specifically dedicated to the project. Patient pathway should be clearly devised to optimize patient care and the resources of all departments. Recruitment of a cohort of patients into a methodology study is valuable to test the quality assurance methods and pathway.« less

Impact of [18F]fluorodeoxyglucose PET-CT staging on treatment planning in radiotherapy incorporating elective nodal irradiation for non-small-cell lung cancer: a prospective study.

PubMed

Kolodziejczyk, Milena; Kepka, Lucyna; Dziuk, Miroslaw; Zawadzka, Anna; Szalus, Norbert; Gizewska, Agnieszka; Bujko, Krzysztof

2011-07-15

To evaluate prospectively how positron emission tomography (PET) information changes treatment plans for non-small-cell lung cancer (NSCLC) patients receiving or not receiving elective nodal irradiation (ENI). One hundred consecutive patients referred for curative radiotherapy were included in the study. Treatment plans were carried out with CT data sets only. For stage III patients, mediastinal ENI was planned. Then, patients underwent PET-CT for diagnostic/planning purposes. PET/CT was fused with the CT data for final planning. New targets were delineated. For stage III patients with minimal N disease (N0-N1, single N2), the ENI was omitted in the new plans. Patients were treated according to the PET-based volumes and plans. The gross tumor volume (GTV)/planning tumor volume (PTV) and doses for critical structures were compared for both data sets. The doses for areas of potential geographical misses derived with the CT data set alone were compared in patients with and without initially planned ENI. In the 75 patients for whom the decision about curative radiotherapy was maintained after PET/CT, there would have been 20 cases (27%) with potential geographical misses by using the CT data set alone. Among them, 13 patients would receive ENI; of those patients, only 2 patients had the PET-based PTV covered by 90% isodose by using the plans based on CT alone, and the mean of the minimum dose within the missed GTV was 55% of the prescribed dose, while for 7 patients without ENI, it was 10% (p = 0.006). The lung, heart, and esophageal doses were significantly lower for plans with ENI omission than for plans with ENI use based on CT alone. PET/CT should be incorporated in the planning of radiotherapy for NSCLC, even in the setting of ENI. However, if PET/CT is unavailable, ENI may to some extent compensate for an inadequate dose coverage resulting from diagnostic uncertainties. Copyright © 2011 Elsevier Inc. All rights reserved.

3D Printing of CT Dataset: Validation of an Open Source and Consumer-Available Workflow.

PubMed

Bortolotto, Chandra; Eshja, Esmeralda; Peroni, Caterina; Orlandi, Matteo A; Bizzotto, Nicola; Poggi, Paolo

2016-02-01

The broad availability of cheap three-dimensional (3D) printing equipment has raised the need for a thorough analysis on its effects on clinical accuracy. Our aim is to determine whether the accuracy of 3D printing process is affected by the use of a low-budget workflow based on open source software and consumer's commercially available 3D printers. A group of test objects was scanned with a 64-slice computed tomography (CT) in order to build their 3D copies. CT datasets were elaborated using a software chain based on three free and open source software. Objects were printed out with a commercially available 3D printer. Both the 3D copies and the test objects were measured using a digital professional caliper. Overall, the objects' mean absolute difference between test objects and 3D copies is 0.23 mm and the mean relative difference amounts to 0.55 %. Our results demonstrate that the accuracy of 3D printing process remains high despite the use of a low-budget workflow.

Recommendations of the Spanish Societies of Radiation Oncology (SEOR), Nuclear Medicine & Molecular Imaging (SEMNiM), and Medical Physics (SEFM) on (18)F-FDG PET-CT for radiotherapy treatment planning.

PubMed

Caballero Perea, Begoña; Villegas, Antonio Cabrera; Rodríguez, José Miguel Delgado; Velloso, María José García; Vicente, Ana María García; Cabrerizo, Carlos Huerga; López, Rosa Morera; Romasanta, Luis Alberto Pérez; Beltrán, Moisés Sáez

2012-01-01

Positron emission tomography (PET) with (18)F-fluorodeoxyglucose (FDG) is a valuable tool for diagnosing and staging malignant lesions. The fusion of PET and computed tomography (CT) yields images that contain both metabolic and morphological information, which, taken together, have improved the diagnostic precision of PET in oncology. The main imaging modality for planning radiotherapy treatment is CT. However, PET-CT is an emerging modality for use in planning treatments because it allows for more accurate treatment volume definition. The use of PET-CT for treatment planning is highly complex, and protocols and standards for its use are still being developed. It seems probable that PET-CT will eventually replace current CT-based planning methods, but this will require a full understanding of the relevant technical aspects of PET-CT planning. The aim of the present document is to review these technical aspects and to provide recommendations for clinical use of this imaging modality in the radiotherapy planning process.

Recommendations of the Spanish Societies of Radiation Oncology (SEOR), Nuclear Medicine & Molecular Imaging (SEMNiM), and Medical Physics (SEFM) on 18F-FDG PET-CT for radiotherapy treatment planning

PubMed Central

Caballero Perea, Begoña; Villegas, Antonio Cabrera; Rodríguez, José Miguel Delgado; Velloso, María José García; Vicente, Ana María García; Cabrerizo, Carlos Huerga; López, Rosa Morera; Romasanta, Luis Alberto Pérez; Beltrán, Moisés Sáez

2012-01-01

Positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) is a valuable tool for diagnosing and staging malignant lesions. The fusion of PET and computed tomography (CT) yields images that contain both metabolic and morphological information, which, taken together, have improved the diagnostic precision of PET in oncology. The main imaging modality for planning radiotherapy treatment is CT. However, PET-CT is an emerging modality for use in planning treatments because it allows for more accurate treatment volume definition. The use of PET-CT for treatment planning is highly complex, and protocols and standards for its use are still being developed. It seems probable that PET-CT will eventually replace current CT-based planning methods, but this will require a full understanding of the relevant technical aspects of PET-CT planning. The aim of the present document is to review these technical aspects and to provide recommendations for clinical use of this imaging modality in the radiotherapy planning process. PMID:24377032

Toward adaptive radiotherapy for head and neck patients: Uncertainties in dose warping due to the choice of deformable registration algorithm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veiga, Catarina, E-mail: catarina.veiga.11@ucl.ac.uk; Royle, Gary; Lourenço, Ana Mónica

2015-02-15

Purpose: The aims of this work were to evaluate the performance of several deformable image registration (DIR) algorithms implemented in our in-house software (NiftyReg) and the uncertainties inherent to using different algorithms for dose warping. Methods: The authors describe a DIR based adaptive radiotherapy workflow, using CT and cone-beam CT (CBCT) imaging. The transformations that mapped the anatomy between the two time points were obtained using four different DIR approaches available in NiftyReg. These included a standard unidirectional algorithm and more sophisticated bidirectional ones that encourage or ensure inverse consistency. The forward (CT-to-CBCT) deformation vector fields (DVFs) were used tomore » propagate the CT Hounsfield units and structures to the daily geometry for “dose of the day” calculations, while the backward (CBCT-to-CT) DVFs were used to remap the dose of the day onto the planning CT (pCT). Data from five head and neck patients were used to evaluate the performance of each implementation based on geometrical matching, physical properties of the DVFs, and similarity between warped dose distributions. Geometrical matching was verified in terms of dice similarity coefficient (DSC), distance transform, false positives, and false negatives. The physical properties of the DVFs were assessed calculating the harmonic energy, determinant of the Jacobian, and inverse consistency error of the transformations. Dose distributions were displayed on the pCT dose space and compared using dose difference (DD), distance to dose difference, and dose volume histograms. Results: All the DIR algorithms gave similar results in terms of geometrical matching, with an average DSC of 0.85 ± 0.08, but the underlying properties of the DVFs varied in terms of smoothness and inverse consistency. When comparing the doses warped by different algorithms, we found a root mean square DD of 1.9% ± 0.8% of the prescribed dose (pD) and that an average of 9% ± 4% of voxels within the treated volume failed a 2%pD DD-test (DD{sub 2%-pp}). Larger DD{sub 2%-pp} was found within the high dose gradient (21% ± 6%) and regions where the CBCT quality was poorer (28% ± 9%). The differences when estimating the mean and maximum dose delivered to organs-at-risk were up to 2.0%pD and 2.8%pD, respectively. Conclusions: The authors evaluated several DIR algorithms for CT-to-CBCT registrations. In spite of all methods resulting in comparable geometrical matching, the choice of DIR implementation leads to uncertainties in dose warped, particularly in regions of high gradient and/or poor imaging quality.« less

First installation of a dual-room IVR-CT system in the emergency room.

PubMed

Wada, Daiki; Nakamori, Yasushi; Kanayama, Shuji; Maruyama, Shuhei; Kawada, Masahiro; Iwamura, Hiromu; Hayakawa, Koichi; Saito, Fukuki; Kuwagata, Yasuyuki

2018-03-05

Computed tomography (CT) embedded in the emergency room has gained importance in the early diagnostic phase of trauma care. In 2011, we implemented a new trauma workflow concept with a sliding CT scanner system with interventional radiology features (IVR-CT) that allows CT examination and emergency therapeutic intervention without relocating the patient, which we call the Hybrid emergency room (Hybrid ER). In the Hybrid ER, all life-saving procedures, CT examination, damage control surgery, and transcatheter arterial embolisation can be performed on the same table. Although the trauma workflow realized in the Hybrid ER may improve mortality in severe trauma, the Hybrid ER can potentially affect the efficacy of other in/outpatient diagnostic workflow because one room is occupied by one severely injured patient undergoing both emergency trauma care and CT scanning for long periods. In July 2017, we implemented a new trauma workflow concept with a dual-room sliding CT scanner system with interventional radiology features (dual-room IVR-CT) to increase patient throughput. When we perform emergency surgery or interventional radiology for a severely injured or ill patient in the Hybrid ER, the sliding CT scanner moves to the adjacent CT suite, and we can perform CT scanning of another in/outpatient. We believe that dual-room IVR-CT can contribute to the improvement of both the survival of severely injured or ill patients and patient throughput.

SU-F-J-169: A Feasibility Study of Using MRI Alone in Abdominal Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zawisza, I; Hsu, S; Peng, Q

Purpose: To demonstrate the feasibility of a MRI alone workflow to support treatment planning and image guidance for abdominal radiotherapy. Methods: Abdominal MR images (in-phase/out-phase/fat/water) were acquired for a patient with breath-hold using a Dixon pulse sequence. Air masks were created on in-phase images using intensity thresholding and morphological processing methods in order to separate air from bone. Pseudo-CT and DRRs were generated using a published method. To investigate the effect of heterogeneity corrections on dose calculations using pseudo-CT, three different plans (3-field 3D, 5-field IMRT and 2-arc VMAT) were performed to mimic pancreatic treatments (1.8Gy/fraction over 28 fractions). Results:more » The DRRs created from pseudo-CT were of comparable quality as those created from CT. Comparing dose calculations with and without heterogeneity corrections between the 3 different plans, the biggest dosimetric differences were seen in the VMAT plan where modulation must occur across air-tissue interfaces such as those of the stomach and bowel. The DVHs for the VMAT plan showed ∼84cc difference at V50Gy in the small bowel. In terms of pseudo-CT quality, some small volumes of air in the bowel and stomach were misclassified as bone. The VMAT plan was re-optimized on pseudo-CT with 0 HU in the misclassified areas. The V50Gy in the small bowel differed by ∼90cc between the new VMAT plan with and without heterogeneity corrections. Conclusion: We found that the use of MRI alone is feasible for abdominal treatment planning and image guidance. A difference between calculations with and without heterogeneity corrections was found that is most pronounced for VMAT where the traversal of air-tissue interfaces is unavoidable. Future work will be performed to minimize misclassification between bone and air.« less

Technical Note: PLASTIMATCH MABS, an open source tool for automatic image segmentation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zaffino, Paolo; Spadea, Maria Francesca

Purpose: Multiatlas based segmentation is largely used in many clinical and research applications. Due to its good performances, it has recently been included in some commercial platforms for radiotherapy planning and surgery guidance. Anyway, to date, a software with no restrictions about the anatomical district and image modality is still missing. In this paper we introduce PLASTIMATCH MABS, an open source software that can be used with any image modality for automatic segmentation. Methods: PLASTIMATCH MABS workflow consists of two main parts: (1) an offline phase, where optimal registration and voting parameters are tuned and (2) an online phase, wheremore » a new patient is labeled from scratch by using the same parameters as identified in the former phase. Several registration strategies, as well as different voting criteria can be selected. A flexible atlas selection scheme is also available. To prove the effectiveness of the proposed software across anatomical districts and image modalities, it was tested on two very different scenarios: head and neck (H&N) CT segmentation for radiotherapy application, and magnetic resonance image brain labeling for neuroscience investigation. Results: For the neurological study, minimum dice was equal to 0.76 (investigated structures: left and right caudate, putamen, thalamus, and hippocampus). For head and neck case, minimum dice was 0.42 for the most challenging structures (optic nerves and submandibular glands) and 0.62 for the other ones (mandible, brainstem, and parotid glands). Time required to obtain the labels was compatible with a real clinical workflow (35 and 120 min). Conclusions: The proposed software fills a gap in the multiatlas based segmentation field, since all currently available tools (both for commercial and for research purposes) are restricted to a well specified application. Furthermore, it can be adopted as a platform for exploring MABS parameters and as a reference implementation for comparing against other segmentation algorithms.« less

The development and implementation of MOSAIQ Integration Platform (MIP) based on the radiotherapy workflow

NASA Astrophysics Data System (ADS)

Yang, Xin; He, Zhen-yu; Jiang, Xiao-bo; Lin, Mao-sheng; Zhong, Ning-shan; Hu, Jiang; Qi, Zhen-yu; Bao, Yong; Li, Qiao-qiao; Li, Bao-yue; Hu, Lian-ying; Lin, Cheng-guang; Gao, Yuan-hong; Liu, Hui; Huang, Xiao-yan; Deng, Xiao-wu; Xia, Yun-fei; Liu, Meng-zhong; Sun, Ying

2017-03-01

To meet the special demands in China and the particular needs for the radiotherapy department, a MOSAIQ Integration Platform CHN (MIP) based on the workflow of radiation therapy (RT) has been developed, as a supplement system to the Elekta MOSAIQ. The MIP adopts C/S (client-server) structure mode, and its database is based on the Treatment Planning System (TPS) and MOSAIQ SQL Server 2008, running on the hospital local network. Five network servers, as a core hardware, supply data storage and network service based on the cloud services. The core software, using C# programming language, is developed based on Microsoft Visual Studio Platform. The MIP server could offer network service, including entry, query, statistics and print information for about 200 workstations at the same time. The MIP was implemented in the past one and a half years, and some practical patient-oriented functions were developed. And now the MIP is almost covering the whole workflow of radiation therapy. There are 15 function modules, such as: Notice, Appointment, Billing, Document Management (application/execution), System Management, and so on. By June of 2016, recorded data in the MIP are as following: 13546 patients, 13533 plan application, 15475 RT records, 14656 RT summaries, 567048 billing records and 506612 workload records, etc. The MIP based on the RT workflow has been successfully developed and clinically implemented with real-time performance, data security, stable operation. And it is demonstrated to be user-friendly and is proven to significantly improve the efficiency of the department. It is a key to facilitate the information sharing and department management. More functions can be added or modified for further enhancement its potentials in research and clinical practice.

Improving the Diagnostic Specificity of CT for Early Detection of Lung Cancer: 4D CT-Based Pulmonary Nodule Elastometry

DTIC Science & Technology

2015-10-01

2012, patients who received stereotactic ablative radiotherapy ( SABR ) for early stage non-small cell lung cancer were included in this study. All...comparing the elasticities of malignant PNs treated with stereotactic ablative radiotherapy ( SABR ) with those of the lung. Methods: We analyzed...breath-hold images of 30 patients with malignant PNs who underwent SABR in our department. A parametric nonrigid transformation model based on multi

Accuracy of radiotherapy dose calculations based on cone-beam CT: comparison of deformable registration and image correction based methods

NASA Astrophysics Data System (ADS)

Marchant, T. E.; Joshi, K. D.; Moore, C. J.

2018-03-01

Radiotherapy dose calculations based on cone-beam CT (CBCT) images can be inaccurate due to unreliable Hounsfield units (HU) in the CBCT. Deformable image registration of planning CT images to CBCT, and direct correction of CBCT image values are two methods proposed to allow heterogeneity corrected dose calculations based on CBCT. In this paper we compare the accuracy and robustness of these two approaches. CBCT images for 44 patients were used including pelvis, lung and head & neck sites. CBCT HU were corrected using a ‘shading correction’ algorithm and via deformable registration of planning CT to CBCT using either Elastix or Niftyreg. Radiotherapy dose distributions were re-calculated with heterogeneity correction based on the corrected CBCT and several relevant dose metrics for target and OAR volumes were calculated. Accuracy of CBCT based dose metrics was determined using an ‘override ratio’ method where the ratio of the dose metric to that calculated on a bulk-density assigned version of the same image is assumed to be constant for each patient, allowing comparison to the patient’s planning CT as a gold standard. Similar performance is achieved by shading corrected CBCT and both deformable registration algorithms, with mean and standard deviation of dose metric error less than 1% for all sites studied. For lung images, use of deformed CT leads to slightly larger standard deviation of dose metric error than shading corrected CBCT with more dose metric errors greater than 2% observed (7% versus 1%).

18-Fluorodeoxy-Glucose Positron Emission Tomography- Computed Tomography (18-FDG-PET/CT) for Gross Tumor Volume (GTV) Delineation in Gastric Cancer Radiotherapy

PubMed

Dębiec, Kinga; Wydmański, Jerzy; Gorczewska, Izabela; Leszczyńska, Paulina; Gorczewski, Kamil; Leszczyński, Wojciech; d’Amico, Andrea; Kalemba, Michał

2017-11-26

Purpose: Evaluation of the 18-fluorodeoxy-glucose positron emission tomography-computed tomography (18-FDGPET/ CT) for gross tumor volume (GTV) delineation in gastric cancer patients undergoing radiotherapy. Methods: In this study, 29 gastric cancer patients (17 unresectable and 7 inoperable) were initially enrolled for radical chemoradiotherapy (45Gy/25 fractions + chemotherapy based on 5 fluorouracil) or radiotherapy alone (45Gy/25 fractions) with planning based on the 18-FDG-PET/CT images. Five patients were excluded due to excess blood glucose levels (1), false-negative positron emission tomography (1) and distant metastases revealed by 18-FDG-PET/CT (3). The analysis involved measurement of metabolic tumor volumes (MTVs) performed on PET/CT workstations. Different threshold levels of the standardized uptake value (SUV) and liver uptake were set to obtain MTVs. Secondly, GTVPET values were derived manually using the positron emission tomography (PET) dataset blinded to the computed tomography (CT) data. Subsequently, GTVCT values were delineated using a radiotherapy planning system based on the CT scans blinded to the PET data. The referenced GTVCT values were correlated with the GTVPET and were compared with a conformality index (CI). Results: The mean CI was 0.52 (range, 0.12-0.85). In 13/24 patients (54%), the GTVPET was larger than GTVCT, and in the remainder, GTVPET was smaller. Moreover, the cranio-caudal diameter of GTVPET in 16 cases (64%) was larger than that of GTVCT, smaller in 7 cases (29%), and unchanged in one case. Manual PET delineation (GTVPET) achieved the best correlation with GTVCT (Pearson correlation = 0.76, p <0.0001). Among the analyzed MTVs, a statistically significant correlation with GTVCT was revealed for MTV10%SUVmax (r = 0.63; p = 0.0014), MTVliv (r = 0.60; p = 0.0021), MTVSUV2.5 (r = 0.54; p = 0.0063); MTV20%SUVmax (r = 0.44; p = 0.0344); MTV30%SUVmax (r = 0.44; p = 0.0373). Conclusion: 18-FDG-PET/CT in gastric cancer radiotherapy planning may affect the GTV delineation. https://www.ncbi.nlm.nih.gov/pubmed/management

Sci-Fri PM: Radiation Therapy, Planning, Imaging, and Special Techniques - 08: Retrospective Dose Accumulation Workflow in Head and Neck Cancer Patients Using RayStation 4.5.2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wong, Olive; Chan, Biu; Moseley, Joanne

Purpose: We have developed a semi-automated dose accumulation workflow for Head and Neck Cancer (HNC) patients to evaluate volumetric and dosimetric changes that take place during radiotherapy. This work will be used to assess how dosimetric changes affect both toxicity and disease control, hence inform the feasibility and design of a prospective HNC adaptive trial. Methods: RayStation 4.5.2 features deformable image registration (DIR), where structures already defined on the planning CT image set can be deformably mapped onto cone-beam computed tomography (CBCT) images, accounting for daily treatment set-up shifts and changes in patient anatomy. The daily delivered dose can bemore » calculated on each CBCT and mapped back to the planning CT to allow dose accumulation. The process is partially automated using Python scripts developed in collaboration with RaySearch. Results: To date we have performed dose accumulation on 18 HNC patients treated at our institution during 2013–2015 under REB approval. Our semi-automated process establishes clinical feasibility. Generally, dose accumulation for the entire treatment course of one case takes 60–120 minutes: importing all CBCTs requires 20–30 minutes as each patient has 30 to 40 treated fractions; image registration and dose accumulation require 60–90 minutes. This is in contrast to the process without automated scripts where dose accumulation alone would take 3–5 hours. Conclusions: We have developed a reliable workflow for retrospective dose tracking in HNC using RayStation. The process has been validated for HNC patients treated on both Elekta and Varian linacs with CBCTs acquired on XVI and OBI platforms respectively.« less

A Web application for the management of clinical workflow in image-guided and adaptive proton therapy for prostate cancer treatments.

PubMed

Yeung, Daniel; Boes, Peter; Ho, Meng Wei; Li, Zuofeng

2015-05-08

Image-guided radiotherapy (IGRT), based on radiopaque markers placed in the prostate gland, was used for proton therapy of prostate patients. Orthogonal X-rays and the IBA Digital Image Positioning System (DIPS) were used for setup correction prior to treatment and were repeated after treatment delivery. Following a rationale for margin estimates similar to that of van Herk,(1) the daily post-treatment DIPS data were analyzed to determine if an adaptive radiotherapy plan was necessary. A Web application using ASP.NET MVC5, Entity Framework, and an SQL database was designed to automate this process. The designed features included state-of-the-art Web technologies, a domain model closely matching the workflow, a database-supporting concurrency and data mining, access to the DIPS database, secured user access and roles management, and graphing and analysis tools. The Model-View-Controller (MVC) paradigm allowed clean domain logic, unit testing, and extensibility. Client-side technologies, such as jQuery, jQuery Plug-ins, and Ajax, were adopted to achieve a rich user environment and fast response. Data models included patients, staff, treatment fields and records, correction vectors, DIPS images, and association logics. Data entry, analysis, workflow logics, and notifications were implemented. The system effectively modeled the clinical workflow and IGRT process.

Systematic evaluation of three different commercial software solutions for automatic segmentation for adaptive therapy in head-and-neck, prostate and pleural cancer.

PubMed

La Macchia, Mariangela; Fellin, Francesco; Amichetti, Maurizio; Cianchetti, Marco; Gianolini, Stefano; Paola, Vitali; Lomax, Antony J; Widesott, Lamberto

2012-09-18

To validate, in the context of adaptive radiotherapy, three commercial software solutions for atlas-based segmentation. Fifteen patients, five for each group, with cancer of the Head&Neck, pleura, and prostate were enrolled in the study. In addition to the treatment planning CT (pCT) images, one replanning CT (rCT) image set was acquired for each patient during the RT course. Three experienced physicians outlined on the pCT and rCT all the volumes of interest (VOIs). We used three software solutions (VelocityAI 2.6.2 (V), MIM 5.1.1 (M) by MIMVista and ABAS 2.0 (A) by CMS-Elekta) to generate the automatic contouring on the repeated CT. All the VOIs obtained with automatic contouring (AC) were successively corrected manually. We recorded the time needed for: 1) ex novo ROIs definition on rCT; 2) generation of AC by the three software solutions; 3) manual correction of AC.To compare the quality of the volumes obtained automatically by the software and manually corrected with those drawn from scratch on rCT, we used the following indexes: overlap coefficient (DICE), sensitivity, inclusiveness index, difference in volume, and displacement differences on three axes (x, y, z) from the isocenter. The time saved by the three software solutions for all the sites, compared to the manual contouring from scratch, is statistically significant and similar for all the three software solutions. The time saved for each site are as follows: about an hour for Head&Neck, about 40 minutes for prostate, and about 20 minutes for mesothelioma. The best DICE similarity coefficient index was obtained with the manual correction for: A (contours for prostate), A and M (contours for H&N), and M (contours for mesothelioma). From a clinical point of view, the automated contouring workflow was shown to be significantly shorter than the manual contouring process, even though manual correction of the VOIs is always needed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Negahdar, M; Loo, B; Maxim, P

Purpose: Elasticity may distinguish malignant from benign pulmonary nodules. To compare determining of malignant pulmonary nodule (MPN) elasticity from four dimensional computed tomography (4D CT) images versus inhale/exhale breath-hold CT images. Methods: We analyzed phase 00 and 50 of 4D CT and deep inhale and natural exhale of breath-hold CT images of 30 MPN treated with stereotactic ablative radiotherapy (SABR). The radius of the smallest MPN was 0.3 cm while the biggest one was 2.1 cm. An intensity based deformable image registration (DIR) workflow was applied to the 4D CT and breath-hold images to determine the volumes of the MPNsmore » and a 1 cm ring of surrounding lung tissue (ring) in each state. Next, an elasticity parameter was derived by calculating the ratio of the volume changes of MPN (exhale:inhale or phase50:phase00) to that of a 1 cm ring of lung tissue surrounding the MPN. The proposed formulation of elasticity enables us to compare volume changes of two different MPN in two different locations of lung. Results: The calculated volume ratio of MPNs from 4D CT (phase50:phase00) and breath-hold images (exhale:inhale) was 1.00±0.23 and 0.95±0.11, respectively. It shows the stiffness of MPN and comparably bigger volume changes of MPN in breath-hold images because of the deeper degree of inhalation. The calculated elasticity of MPNs from 4D CT and breath-hold images was 1.12±0.22 and 1.23±0.26, respectively. For five patients who have had two MPN in their lung, calculated elasticity of tumor A and tumor B follows same trend in both 4D CT and breath-hold images. Conclusion: We showed that 4D CT and breath-hold images are comparable in the ability to calculate the elasticity of MPN. This study has been supported by Department of Defense LCRP 2011 #W81XWH-12-1-0286.« less

Intelligent ePR system for evidence-based research in radiotherapy: proton therapy for prostate cancer.

PubMed

Le, Anh H; Liu, Brent; Schulte, Reinhard; Huang, H K

2011-11-01

Proton therapy (PT) utilizes high energy particle proton beam to kill cancer cells at the target region for target cancer therapy. Due to the physical properties of the proton beam, PT delivers dose with higher precision and no exit dose compared to conventional radiotherapy. In PT, patient data are distributed among multiple systems, a hindrance to research on efficacy and effectiveness. A data mining method and a treatment plan navigator utilizing the infrastructure and data repository of a PT electronic patient record (ePR) was developed to minimize radiation toxicity and improve outcomes in prostate cancer treatment. MATERIALS/METHOD(S): The workflow of a proton therapy treatment in a radiation oncology department was reviewed, and a clinical data model and data flow were designed. A prototype PT ePR system with DICOM compliance was developed to manage prostate cancer patient images, treatment plans, and related clinical data. The ePR system consists of four main components: (1) Data Gateway; (2) ePR Server; (3) Decision Support Tools; and (4) Visualization and Display Tools. Decision support and visualization tools are currently developed based on DICOM images, DICOM-RT and DICOM-RT-ION objects data from prostate cancer patients treated with hypofractionation protocol proton therapy were used for evaluating ePR system effectiveness. Each patient data set includes a set of computed tomography (CT) DICOM images and four DICOM-RT and RT-ION objects. In addition, clinical outcomes data collected from PT cases were included to establish a knowledge base for outcomes analysis. A data mining search engine and an intelligent treatment plan navigator (ITPN) were developed and integrated with the ePR system. Evaluation was based on a data set of 39 PT patients and a hypothetical patient. The ePR system was able to facilitate the proton therapy workflow. The PT ePR system was feasible for prostate cancer patient treated with hypofractionation protocol in proton therapy. This ePR system improves efficiency in data collection and integration to facilitate outcomes analysis.

The Japan Lung Cancer Society–Japanese Society for Radiation Oncology consensus-based computed tomographic atlas for defining regional lymph node stations in radiotherapy for lung cancer

PubMed Central

Itazawa, Tomoko; Tamaki, Yukihisa; Komiyama, Takafumi; Nishimura, Yasumasa; Nakayama, Yuko; Ito, Hiroyuki; Ohde, Yasuhisa; Kusumoto, Masahiko; Sakai, Shuji; Suzuki, Kenji; Watanabe, Hirokazu; Asamura, Hisao

2017-01-01

The purpose of this study was to develop a consensus-based computed tomographic (CT) atlas that defines lymph node stations in radiotherapy for lung cancer based on the lymph node map of the International Association for the Study of Lung Cancer (IASLC). A project group in the Japanese Radiation Oncology Study Group (JROSG) initially prepared a draft of the atlas in which lymph node Stations 1–11 were illustrated on axial CT images. Subsequently, a joint committee of the Japan Lung Cancer Society (JLCS) and the Japanese Society for Radiation Oncology (JASTRO) was formulated to revise this draft. The committee consisted of four radiation oncologists, four thoracic surgeons and three thoracic radiologists. The draft prepared by the JROSG project group was intensively reviewed and discussed at four meetings of the committee over several months. Finally, we proposed definitions for the regional lymph node stations and the consensus-based CT atlas. This atlas was approved by the Board of Directors of JLCS and JASTRO. This resulted in the first official CT atlas for defining regional lymph node stations in radiotherapy for lung cancer authorized by the JLCS and JASTRO. In conclusion, the JLCS–JASTRO consensus-based CT atlas, which conforms to the IASLC lymph node map, was established. PMID:27609192

Implementation of a software for REmote COMparison of PARticlE and photon treatment plans: ReCompare.

PubMed

Löck, Steffen; Roth, Klaus; Skripcak, Tomas; Worbs, Mario; Helmbrecht, Stephan; Jakobi, Annika; Just, Uwe; Krause, Mechthild; Baumann, Michael; Enghardt, Wolfgang; Lühr, Armin

2015-09-01

To guarantee equal access to optimal radiotherapy, a concept of patient assignment to photon or particle radiotherapy using remote treatment plan exchange and comparison - ReCompare - was proposed. We demonstrate the implementation of this concept and present its clinical applicability. The ReCompare concept was implemented using a client-server based software solution. A clinical workflow for the remote treatment plan exchange and comparison was defined. The steps required by the user and performed by the software for a complete plan transfer were described and an additional module for dose-response modeling was added. The ReCompare software was successfully tested in cooperation with three external partner clinics and worked meeting all required specifications. It was compatible with several standard treatment planning systems, ensured patient data protection, and integrated in the clinical workflow. The ReCompare software can be applied to support non-particle radiotherapy institutions with the patient-specific treatment decision on the optimal irradiation modality by remote treatment plan exchange and comparison. Copyright © 2015. Published by Elsevier GmbH.

Accuracy and precision of patient positioning for pelvic MR-only radiation therapy using digitally reconstructed radiographs

NASA Astrophysics Data System (ADS)

Kemppainen, R.; Vaara, T.; Joensuu, T.; Kiljunen, T.

2018-03-01

Background and Purpose. Magnetic resonance imaging (MRI) has in recent years emerged as an imaging modality to drive precise contouring of targets and organs at risk in external beam radiation therapy. Moreover, recent advances in MRI enable treatment of cancer without computed tomography (CT) simulation. A commercially available MR-only solution, MRCAT, offers a single-modality approach that provides density information for dose calculation and generation of positioning reference images. We evaluated the accuracy of patient positioning based on MRCAT digitally reconstructed radiographs (DRRs) by comparing to standard CT based workflow. Materials and Methods. Twenty consecutive prostate cancer patients being treated with external beam radiation therapy were included in the study. DRRs were generated for each patient based on the planning CT and MRCAT. The accuracy assessment was performed by manually registering the DRR images to planar kV setup images using bony landmarks. A Bayesian linear mixed effects model was used to separate systematic and random components (inter- and intra-observer variation) in the assessment. In addition, method agreement was assessed using a Bland-Altman analysis. Results. The systematic difference between MRCAT and CT based patient positioning, averaged over the study population, were found to be (mean [95% CI])  -0.49 [-0.85 to  -0.13] mm, 0.11 [-0.33 to  +0.57] mm and  -0.05 [-0.23 to  +0.36] mm in vertical, longitudinal and lateral directions, respectively. The increases in total random uncertainty were estimated to be below 0.5 mm for all directions, when using MR-only workflow instead of CT. Conclusions. The MRCAT pseudo-CT method provides clinically acceptable accuracy and precision for patient positioning for pelvic radiation therapy based on planar DRR images. Furthermore, due to the reduction of geometric uncertainty, compared to dual-modality workflow, the approach is likely to improve the total geometric accuracy of pelvic radiation therapy.

Multi-atlas-based CT synthesis from conventional MRI with patch-based refinement for MRI-based radiotherapy planning

NASA Astrophysics Data System (ADS)

Lee, Junghoon; Carass, Aaron; Jog, Amod; Zhao, Can; Prince, Jerry L.

2017-02-01

Accurate CT synthesis, sometimes called electron density estimation, from MRI is crucial for successful MRI-based radiotherapy planning and dose computation. Existing CT synthesis methods are able to synthesize normal tissues but are unable to accurately synthesize abnormal tissues (i.e., tumor), thus providing a suboptimal solution. We propose a multiatlas- based hybrid synthesis approach that combines multi-atlas registration and patch-based synthesis to accurately synthesize both normal and abnormal tissues. Multi-parametric atlas MR images are registered to the target MR images by multi-channel deformable registration, from which the atlas CT images are deformed and fused by locally-weighted averaging using a structural similarity measure (SSIM). Synthetic MR images are also computed from the registered atlas MRIs by using the same weights used for the CT synthesis; these are compared to the target patient MRIs allowing for the assessment of the CT synthesis fidelity. Poor synthesis regions are automatically detected based on the fidelity measure and refined by a patch-based synthesis. The proposed approach was tested on brain cancer patient data, and showed a noticeable improvement for the tumor region.

Multi-atlas-based CT synthesis from conventional MRI with patch-based refinement for MRI-based radiotherapy planning.

PubMed

Lee, Junghoon; Carass, Aaron; Jog, Amod; Zhao, Can; Prince, Jerry L

2017-02-01

Accurate CT synthesis, sometimes called electron density estimation, from MRI is crucial for successful MRI-based radiotherapy planning and dose computation. Existing CT synthesis methods are able to synthesize normal tissues but are unable to accurately synthesize abnormal tissues (i.e., tumor), thus providing a suboptimal solution. We propose a multi-atlas-based hybrid synthesis approach that combines multi-atlas registration and patch-based synthesis to accurately synthesize both normal and abnormal tissues. Multi-parametric atlas MR images are registered to the target MR images by multi-channel deformable registration, from which the atlas CT images are deformed and fused by locally-weighted averaging using a structural similarity measure (SSIM). Synthetic MR images are also computed from the registered atlas MRIs by using the same weights used for the CT synthesis; these are compared to the target patient MRIs allowing for the assessment of the CT synthesis fidelity. Poor synthesis regions are automatically detected based on the fidelity measure and refined by a patch-based synthesis. The proposed approach was tested on brain cancer patient data, and showed a noticeable improvement for the tumor region.

How to use PET/CT in the evaluation of response to radiotherapy.

PubMed

Decazes, Pierre; Thureau, Sébastien; Dubray, Bernard; Vera, Pierre

2018-06-01

Radiotherapy is a major treatment modality for many cancers. Tumor response after radiotherapy determines the subsequent steps of the patient's management (surveillance, adjuvant or salvage treatment and palliative care). Tumor response assessed during radiotherapy offers a promising opportunity to adapt the treatment plan to reduced or increased target volume, to specifically target sub-volumes with relevant biological characteristics (metabolism, hypoxia, proliferation, etc.) and to further spare the organs at risk. In addition to its role in the diagnosis and the initial staging, Positron Emission Tomography combined with a Computed Tomography (PET/CT) provides functional information and is therefore attractive to evaluate tumor response. The aim of this paper is to review the published data addressing PET/CT as an evaluation tool in irradiated tumors. Reports on PET/CT acquired at various times (during radiotherapy, after initial (chemo-) radiotherapy, after definitive radiotherapy and during posttreatment follow-up) in solid tumors (lung, head-and-neck, cervix, esophagus, prostate and rectum) were collected and reviewed. Various tracers and technical aspects are also discussed. 18F-FDG PET/CT has a well-established role in clinical routine after definitive chemo-radiotherapy for locally advanced head-and-neck cancers. 18F-choline PET/CT is indicated in prostate cancer patients with biochemical failure. 18F-FDG PET/CT is optional in many other circumstances and the clinical benefits of assessing tumor response with PET/CT remain a field of very active research. The combination of PET with Magnetic Resonance Imaging (PET/MRI) may prove to be valuable in irradiated rectal and cervix cancers. Tumor response can be evaluated by PET/CT with clinical consequences in multiple situations, notably in head and neck and prostate cancers, after radiotherapy. Further clinical evaluation for most cancers is still needed, possibly in association to MRI.

Potential of knowledge discovery using workflows implemented in the C3Grid

NASA Astrophysics Data System (ADS)

Engel, Thomas; Fink, Andreas; Ulbrich, Uwe; Schartner, Thomas; Dobler, Andreas; Fritzsch, Bernadette; Hiller, Wolfgang; Bräuer, Benny

2013-04-01

With the increasing number of climate simulations, reanalyses and observations, new infrastructures to search and analyse distributed data are necessary. In recent years, the Grid architecture became an important technology to fulfill these demands. For the German project "Collaborative Climate Community Data and Processing Grid" (C3Grid) computer scientists and meteorologists developed a system that offers its users a webinterface to search and download climate data and use implemented analysis tools (called workflows) to further investigate them. In this contribution, two workflows that are implemented in the C3Grid architecture are presented: the Cyclone Tracking (CT) and Stormtrack workflow. They shall serve as an example on how to perform numerous investigations on midlatitude winterstorms on a large amount of analysis and climate model data without having an insight into the data source, program code and a low-to-moderate understanding of the theortical background. CT is based on the work of Murray and Simmonds (1991) to identify and track local minima in the mean sea level pressure (MSLP) field of the selected dataset. Adjustable thresholds for the curvature of the isobars as well as the minimum lifetime of a cyclone allow the distinction of weak subtropical heat low systems and stronger midlatitude cyclones e.g. in the Northern Atlantic. The user gets the resulting track data including statistics about the track density, average central pressure, average central curvature, cyclogenesis and cyclolysis as well as pre-built visualizations of these results. Stormtrack calculates the 2.5-6 day bandpassfiltered standard deviation of the geopotential height on a selected pressure level. Although this workflow needs much less computational effort compared to CT it shows structures that are in good agreement with the track density of the CT workflow. To what extent changes in the mid-level tropospheric storm track are reflected in trough density and intensity alteration of surface cyclones. A specific feature of C3Grid is the flexible Workflow Scheduling Service (WSS) which also allows for automated nightly analysis runs of CT, Stormtrack, etc. with different input parameter sets. The statistical results of these workflows can be accumulated afterwards by a scheduled final analysis step, thereby providing a tool for data intensive analytics for the massive amounts of climate model data accessible through C3Grid. First tests with these automated analysis workflows show promising results to speed up the investigation of high volume modeling data. This example is relevant to the thorough analysis of future changes in storminess in Europe and is just one example of the potential of knowledge discovery using automated workflows implemented in the C3Grid architecture.

MRI-Only Based Radiotherapy Treatment Planning for the Rat Brain on a Small Animal Radiation Research Platform (SARRP).

PubMed

Gutierrez, Shandra; Descamps, Benedicte; Vanhove, Christian

2015-01-01

Computed tomography (CT) is the standard imaging modality in radiation therapy treatment planning (RTP). However, magnetic resonance (MR) imaging provides superior soft tissue contrast, increasing the precision of target volume selection. We present MR-only based RTP for a rat brain on a small animal radiation research platform (SARRP) using probabilistic voxel classification with multiple MR sequences. Six rat heads were imaged, each with one CT and five MR sequences. The MR sequences were: T1-weighted, T2-weighted, zero-echo time (ZTE), and two ultra-short echo time sequences with 20 μs (UTE1) and 2 ms (UTE2) echo times. CT data were manually segmented into air, soft tissue, and bone to obtain the RTP reference. Bias field corrected MR images were automatically segmented into the same tissue classes using a fuzzy c-means segmentation algorithm with multiple images as input. Similarities between segmented CT and automatic segmented MR (ASMR) images were evaluated using Dice coefficient. Three ASMR images with high similarity index were used for further RTP. Three beam arrangements were investigated. Dose distributions were compared by analysing dose volume histograms. The highest Dice coefficients were obtained for the ZTE-UTE2 combination and for the T1-UTE1-T2 combination when ZTE was unavailable. Both combinations, along with UTE1-UTE2, often used to generate ASMR images, were used for further RTP. Using 1 beam, MR based RTP underestimated the dose to be delivered to the target (range: 1.4%-7.6%). When more complex beam configurations were used, the calculated dose using the ZTE-UTE2 combination was the most accurate, with 0.7% deviation from CT, compared to 0.8% for T1-UTE1-T2 and 1.7% for UTE1-UTE2. The presented MR-only based workflow for RTP on a SARRP enables both accurate organ delineation and dose calculations using multiple MR sequences. This method can be useful in longitudinal studies where CT's cumulative radiation dose might contribute to the total dose.

Magnetic resonance imaging in precision radiation therapy for lung cancer

PubMed Central

Bainbridge, Hannah; Salem, Ahmed; Tijssen, Rob H. N.; Dubec, Michael; Wetscherek, Andreas; Van Es, Corinne; Belderbos, Jose; Faivre-Finn, Corinne

2017-01-01

Radiotherapy remains the cornerstone of curative treatment for inoperable locally advanced lung cancer, given concomitantly with platinum-based chemotherapy. With poor overall survival, research efforts continue to explore whether integration of advanced radiation techniques will assist safe treatment intensification with the potential for improving outcomes. One advance is the integration of magnetic resonance imaging (MRI) in the treatment pathway, providing anatomical and functional information with excellent soft tissue contrast without exposure of the patient to radiation. MRI may complement or improve the diagnostic staging accuracy of F-18 fluorodeoxyglucose position emission tomography and computerized tomography imaging, particularly in assessing local tumour invasion and is also effective for identification of nodal and distant metastatic disease. Incorporating anatomical MRI sequences into lung radiotherapy treatment planning is a novel application and may improve target volume and organs at risk delineation reproducibility. Furthermore, functional MRI may facilitate dose painting for heterogeneous target volumes and prediction of normal tissue toxicity to guide adaptive strategies. MRI sequences are rapidly developing and although the issue of intra-thoracic motion has historically hindered the quality of MRI due to the effect of motion, progress is being made in this field. Four-dimensional MRI has the potential to complement or supersede 4D CT and 4D F-18-FDG PET, by providing superior spatial resolution. A number of MR-guided radiotherapy delivery units are now available, combining a radiotherapy delivery machine (linear accelerator or cobalt-60 unit) with MRI at varying magnetic field strengths. This novel hybrid technology is evolving with many technical challenges to overcome. It is anticipated that the clinical benefits of MR-guided radiotherapy will be derived from the ability to adapt treatment on the fly for each fraction and in real-time, using ‘beam-on’ imaging. The lung tumour site group of the Atlantic MR-Linac consortium is working to generate a challenging MR-guided adaptive workflow for multi-institution treatment intensification trials in this patient group. PMID:29218271

SU-G-TeP1-05: Development and Clinical Introduction of Automated Radiotherapy Treatment Planning for Prostate Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Winkel, D; Bol, GH; Asselen, B van

Purpose: To develop an automated radiotherapy treatment planning and optimization workflow for prostate cancer in order to generate clinical treatment plans. Methods: A fully automated radiotherapy treatment planning and optimization workflow was developed based on the treatment planning system Monaco (Elekta AB, Stockholm, Sweden). To evaluate our method, a retrospective planning study (n=100) was performed on patients treated for prostate cancer with 5 field intensity modulated radiotherapy, receiving a dose of 35×2Gy to the prostate and vesicles and a simultaneous integrated boost of 35×0.2Gy to the prostate only. A comparison was made between the dosimetric values of the automatically andmore » manually generated plans. Operator time to generate a plan and plan efficiency was measured. Results: A comparison of the dosimetric values show that automatically generated plans yield more beneficial dosimetric values. In automatic plans reductions of 43% in the V72Gy of the rectum and 13% in the V72Gy of the bladder are observed when compared to the manually generated plans. Smaller variance in dosimetric values is seen, i.e. the intra- and interplanner variability is decreased. For 97% of the automatically generated plans and 86% of the clinical plans all criteria for target coverage and organs at risk constraints are met. The amount of plan segments and monitor units is reduced by 13% and 9% respectively. Automated planning requires less than one minute of operator time compared to over an hour for manual planning. Conclusion: The automatically generated plans are highly suitable for clinical use. The plans have less variance and a large gain in time efficiency has been achieved. Currently, a pilot study is performed, comparing the preference of the clinician and clinical physicist for the automatic versus manual plan. Future work will include expanding our automated treatment planning method to other tumor sites and develop other automated radiotherapy workflows.« less

TU-PIS-Exhibit Hall-3: Simultaneous tracking of patient and real time staff dose to optimize interventional workflow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boon, S.

The current clinical standard of organ respiratory imaging, 4D-CT, is fundamentally limited by poor soft-tissue contrast and imaging dose. These limitations are potential barriers to beneficial “4D” radiotherapy methods which optimize the target and OAR dose-volume considering breathing motion but rely on a robust motion characterization. Conversely, MRI imparts no known radiation risk and has excellent soft-tissue contrast. MRI-based motion management is therefore highly desirable and holds great promise to improve radiotherapy of moving cancers, particularly in the abdomen. Over the past decade, MRI techniques have improved significantly, making MR-based motion management clinically feasible. For example, cine MRI has highmore » temporal resolution up to 10 f/s and has been used to track and/or characterize tumor motion, study correlation between external and internal motions. New MR technologies, such as 4D-MRI and MRI hybrid treatment machines (i.e. MR-linac or MR-Co60), have been recently developed. These technologies can lead to more accurate target volume determination and more precise radiation dose delivery via direct tumor gating or tracking. Despite all these promises, great challenges exist and the achievable clinical benefit of MRI-based tumor motion management has yet to be fully explored, much less realized. In this proposal, we will review novel MR-based motion management methods and technologies, the state-of-the-art concerning MRI development and clinical application and the barriers to more widespread adoption. Learning Objectives: Discuss the need of MR-based motion management for improving patient care in radiotherapy. Understand MR techniques for motion imaging and tumor motion characterization. Understand the current state of the art and future steps for clinical integration. Henry Ford Health System holds research agreements with Philips Healthcare. Research sponsored in part by a Henry Ford Health System Internal Mentored Grant.« less

MRI simulation: end-to-end testing for prostate radiation therapy using geometric pelvic MRI phantoms

NASA Astrophysics Data System (ADS)

Sun, Jidi; Dowling, Jason; Pichler, Peter; Menk, Fred; Rivest-Henault, David; Lambert, Jonathan; Parker, Joel; Arm, Jameen; Best, Leah; Martin, Jarad; Denham, James W.; Greer, Peter B.

2015-04-01

To clinically implement MRI simulation or MRI-alone treatment planning requires comprehensive end-to-end testing to ensure an accurate process. The purpose of this study was to design and build a geometric phantom simulating a human male pelvis that is suitable for both CT and MRI scanning and use it to test geometric and dosimetric aspects of MRI simulation including treatment planning and digitally reconstructed radiograph (DRR) generation. A liquid filled pelvic shaped phantom with simulated pelvic organs was scanned in a 3T MRI simulator with dedicated radiotherapy couch-top, laser bridge and pelvic coil mounts. A second phantom with the same external shape but with an internal distortion grid was used to quantify the distortion of the MR image. Both phantoms were also CT scanned as the gold-standard for both geometry and dosimetry. Deformable image registration was used to quantify the MR distortion. Dose comparison was made using a seven-field IMRT plan developed on the CT scan with the fluences copied to the MR image and recalculated using bulk electron densities. Without correction the maximum distortion of the MR compared with the CT scan was 7.5 mm across the pelvis, while this was reduced to 2.6 and 1.7 mm by the vendor’s 2D and 3D correction algorithms, respectively. Within the locations of the internal organs of interest, the distortion was <1.5 and <1 mm with 2D and 3D correction algorithms, respectively. The dose at the prostate isocentre calculated on CT and MRI images differed by 0.01% (1.1 cGy). Positioning shifts were within 1 mm when setup was performed using MRI generated DRRs compared to setup using CT DRRs. The MRI pelvic phantom allows end-to-end testing of the MRI simulation workflow with comparison to the gold-standard CT based process. MRI simulation was found to be geometrically accurate with organ dimensions, dose distributions and DRR based setup within acceptable limits compared to CT.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Sui, E-mail: sshen@uabmc.edu; Jacob, Rojymon; Bender, Luvenia W.

Radiotherapy or stereotactic body radiosurgery (SBRT) requires a sufficient functional liver volume to tolerate the treatment. The current study extended the work of de Graaf et al. (2010) [3] on the use of {sup 99m}Tc-mebrofenin imaging for presurgery planning to radiotherapy planning for liver cancer or metastases. Patient was immobilized and imaged in an identical position on a single-photon emission computed tomography/computed tomography (SPECT-CT) system and a radiotherapy simulation CT system. {sup 99m}Tc-mebrofenin SPECT was registered to the planning CT through image registration of noncontrast CT from SPECT-CT system to the radiotherapy planning CT. The voxels with higher uptake ofmore » {sup 99m}Tc-mebrofenin were transferred to the planning CT as an avoidance structure in optimizing a 2-arc RapidArc plan for SBRT delivery. Excellent dose coverage to the target and sparing of the healthy remnant liver volume was achieved. This report illustrated a procedure for the use of {sup 99m}Tc-mebrofenin SPECT for optimizing radiotherapy for liver cancers and metastases.« less

18 F-FDG PET/CT for planning external beam radiotherapy alters therapy in 11% of 581 patients.

PubMed

Birk Christensen, Charlotte; Loft-Jakobsen, Annika; Munck Af Rosenschöld, Per; Højgaard, Liselotte; Roed, Henrik; Berthelsen, Anne K

2018-03-01

18 F-FDG PET/CT (FDG PET/CT) used in radiotherapy planning for extra-cerebral malignancy may reveal metastases to distant sites that may affect the choice of therapy. To investigate the role of FDG PET/CT on treatment strategy changes induced by the use of PET/CT as part of the radiotherapy planning. 'A major change of treatment strategy' was defined as either including more lesions in the gross tumour volume (GTV) distant from the primary tumour or a change in treatment modalities. The study includes 581 consecutive patients who underwent an FDG PET/CT scan for radiotherapy planning in our institution in the year 2008. All PET/CT scans were performed with the patient in treatment position with the use of immobilization devices according to the intended radiotherapy treatment. All scans were evaluated by a nuclear medicine physician together with a radiologist to delineate PET-positive GTV (GTV-PET). For 63 of the patients (11%), the PET/CT simulation scans resulted in a major change in treatment strategy because of the additional diagnostic information. Changes were most frequently observed in patients with lung cancer (20%) or upper gastrointestinal cancer (12%). In 65% of the patients for whom the PET/CT simulation scan revealed unexpected dissemination, radiotherapy was given - changed (n = 38) or unchanged (n = 13) according to the findings on the FDG PET/CT. Unexpected dissemination on the FDG PET/CT scanning performed for radiotherapy planning caused a change in treatment strategy in 11% of 581 patients. © 2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

A Web application for the management of clinical workflow in image‐guided and adaptive proton therapy for prostate cancer treatments

PubMed Central

Boes, Peter; Ho, Meng Wei; Li, Zuofeng

2015-01-01

Image‐guided radiotherapy (IGRT), based on radiopaque markers placed in the prostate gland, was used for proton therapy of prostate patients. Orthogonal X‐rays and the IBA Digital Image Positioning System (DIPS) were used for setup correction prior to treatment and were repeated after treatment delivery. Following a rationale for margin estimates similar to that of van Herk,(1) the daily post‐treatment DIPS data were analyzed to determine if an adaptive radiotherapy plan was necessary. A Web application using ASP.NET MVC5, Entity Framework, and an SQL database was designed to automate this process. The designed features included state‐of‐the‐art Web technologies, a domain model closely matching the workflow, a database‐supporting concurrency and data mining, access to the DIPS database, secured user access and roles management, and graphing and analysis tools. The Model‐View‐Controller (MVC) paradigm allowed clean domain logic, unit testing, and extensibility. Client‐side technologies, such as jQuery, jQuery Plug‐ins, and Ajax, were adopted to achieve a rich user environment and fast response. Data models included patients, staff, treatment fields and records, correction vectors, DIPS images, and association logics. Data entry, analysis, workflow logics, and notifications were implemented. The system effectively modeled the clinical workflow and IGRT process. PACS number: 87 PMID:26103504

The Japan Lung Cancer Society-Japanese Society for Radiation Oncology consensus-based computed tomographic atlas for defining regional lymph node stations in radiotherapy for lung cancer.

PubMed

Itazawa, Tomoko; Tamaki, Yukihisa; Komiyama, Takafumi; Nishimura, Yasumasa; Nakayama, Yuko; Ito, Hiroyuki; Ohde, Yasuhisa; Kusumoto, Masahiko; Sakai, Shuji; Suzuki, Kenji; Watanabe, Hirokazu; Asamura, Hisao

2017-01-01

The purpose of this study was to develop a consensus-based computed tomographic (CT) atlas that defines lymph node stations in radiotherapy for lung cancer based on the lymph node map of the International Association for the Study of Lung Cancer (IASLC). A project group in the Japanese Radiation Oncology Study Group (JROSG) initially prepared a draft of the atlas in which lymph node Stations 1-11 were illustrated on axial CT images. Subsequently, a joint committee of the Japan Lung Cancer Society (JLCS) and the Japanese Society for Radiation Oncology (JASTRO) was formulated to revise this draft. The committee consisted of four radiation oncologists, four thoracic surgeons and three thoracic radiologists. The draft prepared by the JROSG project group was intensively reviewed and discussed at four meetings of the committee over several months. Finally, we proposed definitions for the regional lymph node stations and the consensus-based CT atlas. This atlas was approved by the Board of Directors of JLCS and JASTRO. This resulted in the first official CT atlas for defining regional lymph node stations in radiotherapy for lung cancer authorized by the JLCS and JASTRO. In conclusion, the JLCS-JASTRO consensus-based CT atlas, which conforms to the IASLC lymph node map, was established. © The Author 2016. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

Development and clinical introduction of automated radiotherapy treatment planning for prostate cancer

NASA Astrophysics Data System (ADS)

Winkel, D.; Bol, G. H.; van Asselen, B.; Hes, J.; Scholten, V.; Kerkmeijer, L. G. W.; Raaymakers, B. W.

2016-12-01

To develop an automated radiotherapy treatment planning and optimization workflow to efficiently create patient specifically optimized clinical grade treatment plans for prostate cancer and to implement it in clinical practice. A two-phased planning and optimization workflow was developed to automatically generate 77Gy 5-field simultaneously integrated boost intensity modulated radiation therapy (SIB-IMRT) plans for prostate cancer treatment. A retrospective planning study (n  =  100) was performed in which automatically and manually generated treatment plans were compared. A clinical pilot (n  =  21) was performed to investigate the usability of our method. Operator time for the planning process was reduced to  <5 min. The retrospective planning study showed that 98 plans met all clinical constraints. Significant improvements were made in the volume receiving 72Gy (V72Gy) for the bladder and rectum and the mean dose of the bladder and the body. A reduced plan variance was observed. During the clinical pilot 20 automatically generated plans met all constraints and 17 plans were selected for treatment. The automated radiotherapy treatment planning and optimization workflow is capable of efficiently generating patient specifically optimized and improved clinical grade plans. It has now been adopted as the current standard workflow in our clinic to generate treatment plans for prostate cancer.

Simulation of pseudo-CT images based on deformable image registration of ultrasound images: A proof of concept for transabdominal ultrasound imaging of the prostate during radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meer, Skadi van der; Camps, Saskia M.; Oncology Solutions Department, Philips Research, High Tech Campus 34, Eindhoven 5656 AE

Purpose: Imaging of patient anatomy during treatment is a necessity for position verification and for adaptive radiotherapy based on daily dose recalculation. Ultrasound (US) image guided radiotherapy systems are currently available to collect US images at the simulation stage (US{sub sim}), coregistered with the simulation computed tomography (CT), and during all treatment fractions. The authors hypothesize that a deformation field derived from US-based deformable image registration can be used to create a daily pseudo-CT (CT{sub ps}) image that is more representative of the patients’ geometry during treatment than the CT acquired at simulation stage (CT{sub sim}). Methods: The three prostatemore » patients, considered to evaluate this hypothesis, had coregistered CT and US scans on various days. In particular, two patients had two US–CT datasets each and the third one had five US–CT datasets. Deformation fields were computed between pairs of US images of the same patient and then applied to the corresponding US{sub sim} scan to yield a new deformed CT{sub ps} scan. The original treatment plans were used to recalculate dose distributions in the simulation, deformed and ground truth CT (CT{sub gt}) images to compare dice similarity coefficients, maximum absolute distance, and mean absolute distance on CT delineations and gamma index (γ) evaluations on both the Hounsfield units (HUs) and the dose. Results: In the majority, deformation did improve the results for all three evaluation methods. The change in gamma failure for dose (γ{sub Dose}, 3%, 3 mm) ranged from an improvement of 11.2% in the prostate volume to a deterioration of 1.3% in the prostate and bladder. The change in gamma failure for the CT images (γ{sub CT}, 50 HU, 3 mm) ranged from an improvement of 20.5% in the anus and rectum to a deterioration of 3.2% in the prostate. Conclusions: This new technique may generate CT{sub ps} images that are more representative of the actual patient anatomy than the CT{sub sim} scan.« less

[Radiotherapy volume delineation based on (18F)-fluorodeoxyglucose positron emission tomography for locally advanced or inoperable oesophageal cancer].

PubMed

Encaoua, J; Abgral, R; Leleu, C; El Kabbaj, O; Caradec, P; Bourhis, D; Pradier, O; Schick, U

2017-06-01

To study the impact on radiotherapy planning of an automatically segmented target volume delineation based on ( 18 F)-fluorodeoxy-D-glucose (FDG)-hybrid positron emission tomography-computed tomography (PET-CT) compared to a manually delineation based on computed tomography (CT) in oesophageal carcinoma patients. Fifty-eight patients diagnosed with oesophageal cancer between September 2009 and November 2014 were included. The majority had squamous cell carcinoma (84.5 %), and advanced stage (37.9 % were stade IIIA) and 44.8 % had middle oesophageal lesion. Gross tumour volumes were retrospectively defined based either manually on CT or automatically on coregistered PET/CT images using three different threshold methods: standard-uptake value (SUV) of 2.5, 40 % of maximum intensity and signal-to-background ratio. Target volumes were compared in length, volume and using the index of conformality. Radiotherapy plans to the dose of 50Gy and 66Gy using intensity-modulated radiotherapy were generated and compared for both data sets. Planification target volume coverage and doses delivered to organs at risk (heart, lung and spinal cord) were compared. The gross tumour volume based manually on CT was significantly longer than that automatically based on signal-to-background ratio (6.4cm versus 5.3cm; P<0.008). Doses to the lungs (V20, D mean ), heart (V40), and spinal cord (D max ) were significantly lower on plans using the PTV SBR . The PTV SBR coverage was statistically better than the PTV CT coverage on both plans. (50Gy: P<0.0004 and 66Gy: P<0.0006). The automatic PET segmentation algorithm based on the signal-to-background ratio method for the delineation of oesophageal tumours is interesting, and results in better target volume coverage and decreased dose to organs at risk. This may allow dose escalation up to 66Gy to the gross tumour volume. Copyright © 2017 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

Simulated Online Adaptive MR-Guided SBRT for the Treatment of Oligometastatic Disease of the Abdomen and Central Thorax: Characterization of Potential Advantages

PubMed Central

Henke, Lauren; Kashani, Rojano; Yang, Deshan; Zhao, Tianyu; Green, Olga; Olsen, Lindsey; Rodriguez, Vivian; Wooten, H. Omar; Li, H. Harold; Hu, Yanle; Bradley, Jeffrey; Robinson, Clifford; Parikh, Parag; Michalski, Jeff; Mutic, Sasa; Olsen, Jeffrey

2017-01-01

Purpose/Objectives Stereotactic body radiotherapy (SBRT) is increasingly used to treat oligometastatic or unresectable primary malignancy, although proximity of organs-at-risk (OAR) may limit delivery of sufficiently ablative dose. Magnetic resonance (MR)-based online-adaptive radiotherapy (ART) has potential to improve SBRT’s therapeutic ratio. This study characterizes potential advantages of online-adaptive MR-guided SBRT to treat oligometastatic disease of the non-liver abdomen and central thorax. Materials/Methods Ten patients treated with RT for unresectable primary or oligometastatic disease of the non-liver abdomen (n=5) or central thorax (n=5) underwent imaging throughout treatment on a clinical MR-IGRT system. SBRT plans were created based on tumor/OAR anatomy at initial CT simulation (PI) and simulated adaptive plans were created based on observed MR-image set tumor/OAR “anatomy-of-the-day” (PA). Each PA was planned under workflow constraints to simulate online-ART. Prescribed dose was 50Gy/5fractions with goal coverage of 95% PTV by 95% of the prescription, subject to hard OAR constraints. PI was applied to each MR dataset and compared to PA to evaluate changes in dose delivered to tumor/OARs, with dose escalation when possible. Results Hard OAR constraints were met for all PI based on anatomy from initial CT simulation, and all PA based on anatomy from each daily MR-image set. Application of the PI to anatomy-of-the-day caused OAR constraint violation in 19/30 cases. Adaptive planning increased PTV coverage in 21/30 cases, including 14 cases where hard OAR constraints were violated by the non-adaptive plan. For 9 PA cases, decreased PTV coverage was required to meet hard OAR constraints that would have been violated in a non-adaptive setting. Conclusions Online-adaptive MRI-guided SBRT may allow PTV dose escalation and/or simultaneous OAR sparing compared to non-adaptive SBRT. A prospective clinical trial is underway at our institution to evaluate clinical outcomes of this technique. PMID:27742541

The impact of 18 F-FET PET-CT on target definition in image-guided stereotactic radiotherapy in patients with skull base lesions.

PubMed

Badakhshi, Harun; Graf, Reinhold; Prasad, Vikas; Budach, Volker

2014-06-25

18 F-fluoro-ethyl-tyrosine PET is gaining more indications in the field of oncology. We investigated the potentials of usage of FET-PET/CT in addition to MRI for definition of gross tumor volume (GTV) in stereotactic radiotherapy of lesions of skull base. We included in a prospective setting 21 cases. An MRI was performed, completed by FET PET/CT. Different GTV's were defined based on respective imaging tools: 1. GTVMRI, 2. GTV MRI /CT, 3. GTV composit (1 + 2), and GTVPET = GTV Boost. Lesions could be visualised by MRI and FET-PET/CT in all patients. FET tracer enhancement was found in all cases. Skull base infiltration by these lesions was observed by MRI, CT (PET/CT) and FET-PET (PET/CT) in all patients. Totally, brain tissue infiltration was seen in 10 patients. While, in 7 (out 10) cases, MRI and CT (from PET/CT) were indicating brain infiltration, FET-PET could add additional information regarding infiltrative behaviour: in 3 (out 10) patients, infiltration of the brain was displayed merely in FET-PET. An enlargement of GTVMRI/CT due to the FET-PET driven information, which revealed GTVcomposite , was necessary in 7 cases,. This enlargement was significant by definition (> 10% of GTVMRI/CT). The mean PET-effect on GTV counted for 1 ± 4 cm3. The restricted boost fields were based mainly on the GTVPET volume. In mean, about 8.5 cm3 of GTVMRI/CT, which showed no FET uptake, were excluded from target volume. GTV boost driven by only-PET-activity, was in mean by 33% smaller than the initial large treatment field, GTV composite, for those cases received boost treatment. FET-PET lead to significant (>10%) changes in the initial treatment fields in 11/21 patients and showed additional tumour volume relevant for radiation planning in 6/21 cases, and led to a subsequent decrease of more than 10% of the initial volumes for the boost fields. The implementation of FET PET into the planning procedures showed a benefit in terms of accurate definition of skull base lesions as targets for Image-guided stereotactic Radiotherapy. This has to be investigated prospectively in larger cohorts.

MRI-Only Based Radiotherapy Treatment Planning for the Rat Brain on a Small Animal Radiation Research Platform (SARRP)

PubMed Central

Gutierrez, Shandra; Descamps, Benedicte; Vanhove, Christian

2015-01-01

Computed tomography (CT) is the standard imaging modality in radiation therapy treatment planning (RTP). However, magnetic resonance (MR) imaging provides superior soft tissue contrast, increasing the precision of target volume selection. We present MR-only based RTP for a rat brain on a small animal radiation research platform (SARRP) using probabilistic voxel classification with multiple MR sequences. Six rat heads were imaged, each with one CT and five MR sequences. The MR sequences were: T1-weighted, T2-weighted, zero-echo time (ZTE), and two ultra-short echo time sequences with 20 μs (UTE1) and 2 ms (UTE2) echo times. CT data were manually segmented into air, soft tissue, and bone to obtain the RTP reference. Bias field corrected MR images were automatically segmented into the same tissue classes using a fuzzy c-means segmentation algorithm with multiple images as input. Similarities between segmented CT and automatic segmented MR (ASMR) images were evaluated using Dice coefficient. Three ASMR images with high similarity index were used for further RTP. Three beam arrangements were investigated. Dose distributions were compared by analysing dose volume histograms. The highest Dice coefficients were obtained for the ZTE-UTE2 combination and for the T1-UTE1-T2 combination when ZTE was unavailable. Both combinations, along with UTE1-UTE2, often used to generate ASMR images, were used for further RTP. Using 1 beam, MR based RTP underestimated the dose to be delivered to the target (range: 1.4%-7.6%). When more complex beam configurations were used, the calculated dose using the ZTE-UTE2 combination was the most accurate, with 0.7% deviation from CT, compared to 0.8% for T1-UTE1-T2 and 1.7% for UTE1-UTE2. The presented MR-only based workflow for RTP on a SARRP enables both accurate organ delineation and dose calculations using multiple MR sequences. This method can be useful in longitudinal studies where CT’s cumulative radiation dose might contribute to the total dose. PMID:26633302

The NUKDOS software for treatment planning in molecular radiotherapy.

PubMed

Kletting, Peter; Schimmel, Sebastian; Hänscheid, Heribert; Luster, Markus; Fernández, Maria; Nosske, Dietmar; Lassmann, Michael; Glatting, Gerhard

2015-09-01

The aim of this work was the development of a software tool for treatment planning prior to molecular radiotherapy, which comprises all functionality to objectively determine the activity to administer and the pertaining absorbed doses (including the corresponding error) based on a series of gamma camera images and one SPECT/CT or probe data. NUKDOS was developed in MATLAB. The workflow is based on the MIRD formalism For determination of the tissue or organ pharmacokinetics, gamma camera images as well as probe, urine, serum and blood activity data can be processed. To estimate the time-integrated activity coefficients (TIAC), sums of exponentials are fitted to the time activity data and integrated analytically. To obtain the TIAC on the voxel level, the voxel activity distribution from the quantitative 3D SPECT/CT (or PET/CT) is used for scaling and weighting the TIAC derived from the 2D organ data. The voxel S-values are automatically calculated based on the voxel-size of the image and the therapeutic nuclide ((90)Y, (131)I or (177)Lu). The absorbed dose coefficients are computed by convolution of the voxel TIAC and the voxel S-values. The activity to administer and the pertaining absorbed doses are determined by entering the absorbed dose for the organ at risk. The overall error of the calculated absorbed doses is determined by Gaussian error propagation. NUKDOS was tested for the operation systems Windows(®) 7 (64 Bit) and 8 (64 Bit). The results of each working step were compared to commercially available (SAAMII, OLINDA/EXM) and in-house (UlmDOS) software. The application of the software is demonstrated using examples form peptide receptor radionuclide therapy (PRRT) and from radioiodine therapy of benign thyroid diseases. For the example from PRRT, the calculated activity to administer differed by 4% comparing NUKDOS and the final result using UlmDos, SAAMII and OLINDA/EXM sequentially. The absorbed dose for the spleen and tumour differed by 7% and 8%, respectively. The results from the example from radioiodine therapy of benign thyroid diseases and the example given in the latest corresponding SOP were identical. The implemented, objective methods facilitate accurate and reproducible results. The software is freely available. Copyright © 2015. Published by Elsevier GmbH.

SU-E-T-287: Dose Verification On the Variation of Target Volume and Organ at Risk in Preradiation Chemotherapy IMRT for Nasopharyngeal Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, X; Kong, L; Wang, J

2015-06-15

Purpose: To quantify the target volume and organ at risk of nasopharyngeal carcinoma (NPC) patients with preradiation chemotherapy based on CT scanned during intensity-modulated radiotherapy (IMRT), and recalculate the dose distribution. Methods: Seven patients with NPC and preradiation chemotherapy, treated with IMRT (35 to 37 fractions) were reviewed. Repeat CT scanning was required to all of the patients during the radiotherapy, and the number of repeat CTs varies from 2 to 6. The plan CT and repeat CT were generated by different CT scanner. To ensure crespectively on the same IMPT plan. The real dose distribution was calculated by deformablemore » registration and weighted method in Raystation (v 4.5.1). The fraction of each dose is based on radiotherapy record. The volumetric and dose differences among these images were calculated for nascIpharyngeal tumor and retro-pharyngeal lymph nodes (GTV-NX), neck lymph nodes(GTV-ND), and parotid glands. Results: The volume variation in GTV-NX from CT1 to CT2 was 1.15±3.79%, and in GTV-LN −0.23±4.93%. The volume variation in left parotid from CT1 to CT2 was −6.79±11.91%, and in right parotid −3.92±8.80%. In patient 2, the left parotid volume were decreased remarkably, as a Result, the V30 and V40 of it were increased as well. Conclusion: The target volume of patients with NPC varied lightly during IMRT. It shows that preradiation chemotherapy can control the target volume variation and perform a good dose repeatability. Also, the decreasing volume of parotid in some patient might increase the dose of it, which might course potential complications.« less

Cine Computed Tomography Without Respiratory Surrogate in Planning Stereotactic Radiotherapy for Non-Small-Cell Lung Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riegel, Adam C. B.A.; Chang, Joe Y.; Vedam, Sastry S.

2009-02-01

Purpose: To determine whether cine computed tomography (CT) can serve as an alternative to four-dimensional (4D)-CT by providing tumor motion information and producing equivalent target volumes when used to contour in radiotherapy planning without a respiratory surrogate. Methods and Materials: Cine CT images from a commercial CT scanner were used to form maximum intensity projection and respiratory-averaged CT image sets. These image sets then were used together to define the targets for radiotherapy. Phantoms oscillating under irregular motion were used to assess the differences between contouring using cine CT and 4D-CT. We also retrospectively reviewed the image sets for 26more » patients (27 lesions) at our institution who had undergone stereotactic radiotherapy for Stage I non-small-cell lung cancer. The patients were included if the tumor motion was >1 cm. The lesions were first contoured using maximum intensity projection and respiratory-averaged CT image sets processed from cine CT and then with 4D-CT maximum intensity projection and 10-phase image sets. The mean ratios of the volume magnitude were compared with intraobserver variation, the mean centroid shifts were calculated, and the volume overlap was assessed with the normalized Dice similarity coefficient index. Results: The phantom studies demonstrated that cine CT captured a greater extent of irregular tumor motion than did 4D-CT, producing a larger tumor volume. The patient studies demonstrated that the gross tumor defined using cine CT imaging was similar to, or slightly larger than, that defined using 4D-CT. Conclusion: The results of our study have shown that cine CT is a promising alternative to 4D-CT for stereotactic radiotherapy planning.« less

(68)Ga-PSMA-11 PET/CT: a new technique with high potential for the radiotherapeutic management of prostate cancer patients.

PubMed

Sterzing, Florian; Kratochwil, Clemens; Fiedler, Hannah; Katayama, Sonja; Habl, Gregor; Kopka, Klaus; Afshar-Oromieh, Ali; Debus, Jürgen; Haberkorn, Uwe; Giesel, Frederik L

2016-01-01

Radiotherapy is the main therapeutic approach besides surgery of localized prostate cancer. It relies on risk stratification and exact staging. This report analyses the potential of [(68)Ga]Glu-urea-Lys(Ahx)-HBED-CC ((68)Ga-PSMA-11), a new positron emission tomography (PET) tracer targeting prostate-specific membrane antigen (PSMA) for prostate cancer staging and individualized radiotherapy planning. A cohort of 57 patients with prostate cancer scanned with (68)Ga-PSMA-11 PET/CT for radiotherapy planning was retrospectively reviewed; 15 patients were at initial diagnosis and 42 patients at time of biochemical recurrence. Staging results of conventional imaging, including bone scintigraphy, CT or MRI, were compared with (68)Ga-PSMA ligand PET/CT results and the influence on radiotherapeutic management was quantified. (68)Ga-PSMA ligand PET/CT had a dramatic impact on radiotherapy application in the presented cohort. In 50.8 % of the cases therapy was changed. The presented imaging technique of (68)Ga-PSMA PET/CT could be a key technology for individualized radiotherapy management in prostate cancer.

Dosimetric verification of radiotherapy treatment planning systems in Serbia: national audit

PubMed Central

2012-01-01

Background Independent external audits play an important role in quality assurance programme in radiation oncology. The audit supported by the IAEA in Serbia was designed to review the whole chain of activities in 3D conformal radiotherapy (3D-CRT) workflow, from patient data acquisition to treatment planning and dose delivery. The audit was based on the IAEA recommendations and focused on dosimetry part of the treatment planning and delivery processes. Methods The audit was conducted in three radiotherapy departments of Serbia. An anthropomorphic phantom was scanned with a computed tomography unit (CT) and treatment plans for eight different test cases involving various beam configurations suggested by the IAEA were prepared on local treatment planning systems (TPSs). The phantom was irradiated following the treatment plans for these test cases and doses in specific points were measured with an ionization chamber. The differences between the measured and calculated doses were reported. Results The measurements were conducted for different photon beam energies and TPS calculation algorithms. The deviation between the measured and calculated values for all test cases made with advanced algorithms were within the agreement criteria, while the larger deviations were observed for simpler algorithms. The number of measurements with results outside the agreement criteria increased with the increase of the beam energy and decreased with TPS calculation algorithm sophistication. Also, a few errors in the basic dosimetry data in TPS were detected and corrected. Conclusions The audit helped the users to better understand the operational features and limitations of their TPSs and resulted in increased confidence in dose calculation accuracy using TPSs. The audit results indicated the shortcomings of simpler algorithms for the test cases performed and, therefore the transition to more advanced algorithms is highly desirable. PMID:22971539

Dosimetric verification of radiotherapy treatment planning systems in Serbia: national audit.

PubMed

Rutonjski, Laza; Petrović, Borislava; Baucal, Milutin; Teodorović, Milan; Cudić, Ozren; Gershkevitsh, Eduard; Izewska, Joanna

2012-09-12

Independent external audits play an important role in quality assurance programme in radiation oncology. The audit supported by the IAEA in Serbia was designed to review the whole chain of activities in 3D conformal radiotherapy (3D-CRT) workflow, from patient data acquisition to treatment planning and dose delivery. The audit was based on the IAEA recommendations and focused on dosimetry part of the treatment planning and delivery processes. The audit was conducted in three radiotherapy departments of Serbia. An anthropomorphic phantom was scanned with a computed tomography unit (CT) and treatment plans for eight different test cases involving various beam configurations suggested by the IAEA were prepared on local treatment planning systems (TPSs). The phantom was irradiated following the treatment plans for these test cases and doses in specific points were measured with an ionization chamber. The differences between the measured and calculated doses were reported. The measurements were conducted for different photon beam energies and TPS calculation algorithms. The deviation between the measured and calculated values for all test cases made with advanced algorithms were within the agreement criteria, while the larger deviations were observed for simpler algorithms. The number of measurements with results outside the agreement criteria increased with the increase of the beam energy and decreased with TPS calculation algorithm sophistication. Also, a few errors in the basic dosimetry data in TPS were detected and corrected. The audit helped the users to better understand the operational features and limitations of their TPSs and resulted in increased confidence in dose calculation accuracy using TPSs. The audit results indicated the shortcomings of simpler algorithms for the test cases performed and, therefore the transition to more advanced algorithms is highly desirable.

Automatic lesion tracking for a PET/CT based computer aided cancer therapy monitoring system

NASA Astrophysics Data System (ADS)

Opfer, Roland; Brenner, Winfried; Carlsen, Ingwer; Renisch, Steffen; Sabczynski, Jörg; Wiemker, Rafael

2008-03-01

Response assessment of cancer therapy is a crucial component towards a more effective and patient individualized cancer therapy. Integrated PET/CT systems provide the opportunity to combine morphologic with functional information. However, dealing simultaneously with several PET/CT scans poses a serious workflow problem. It can be a difficult and tedious task to extract response criteria based upon an integrated analysis of PET and CT images and to track these criteria over time. In order to improve the workflow for serial analysis of PET/CT scans we introduce in this paper a fast lesion tracking algorithm. We combine a global multi-resolution rigid registration algorithm with a local block matching and a local region growing algorithm. Whenever the user clicks on a lesion in the base-line PET scan the course of standardized uptake values (SUV) is automatically identified and shown to the user as a graph plot. We have validated our method by a data collection from 7 patients. Each patient underwent two or three PET/CT scans during the course of a cancer therapy. An experienced nuclear medicine physician manually measured the courses of the maximum SUVs for altogether 18 lesions. As a result we obtained that the automatic detection of the corresponding lesions resulted in SUV measurements which are nearly identical to the manually measured SUVs. Between 38 measured maximum SUVs derived from manual and automatic detected lesions we observed a correlation of 0.9994 and a average error of 0.4 SUV units.

Needle and catheter navigation using electromagnetic tracking for computer-assisted C-arm CT interventions

NASA Astrophysics Data System (ADS)

Nagel, Markus; Hoheisel, Martin; Petzold, Ralf; Kalender, Willi A.; Krause, Ulrich H. W.

2007-03-01

Integrated solutions for navigation systems with CT, MR or US systems become more and more popular for medical products. Such solutions improve the medical workflow, reduce hardware, space and costs requirements. The purpose of our project was to develop a new electromagnetic navigation system for interventional radiology which is integrated into C-arm CT systems. The application is focused on minimally invasive percutaneous interventions performed under local anaesthesia. Together with a vacuum-based patient immobilization device and newly developed navigation tools (needles, panels) we developed a safe and fully automatic navigation system. The radiologist can directly start with navigated interventions after loading images without any prior user interaction. The complete system is adapted to the requirements of the radiologist and to the clinical workflow. For evaluation of the navigation system we performed different phantom studies and achieved an average accuracy of better than 2.0 mm.

An automated workflow for patient-specific quality control of contour propagation

NASA Astrophysics Data System (ADS)

Beasley, William J.; McWilliam, Alan; Slevin, Nicholas J.; Mackay, Ranald I.; van Herk, Marcel

2016-12-01

Contour propagation is an essential component of adaptive radiotherapy, but current contour propagation algorithms are not yet sufficiently accurate to be used without manual supervision. Manual review of propagated contours is time-consuming, making routine implementation of real-time adaptive radiotherapy unrealistic. Automated methods of monitoring the performance of contour propagation algorithms are therefore required. We have developed an automated workflow for patient-specific quality control of contour propagation and validated it on a cohort of head and neck patients, on which parotids were outlined by two observers. Two types of error were simulated—mislabelling of contours and introducing noise in the scans before propagation. The ability of the workflow to correctly predict the occurrence of errors was tested, taking both sets of observer contours as ground truth, using receiver operator characteristic analysis. The area under the curve was 0.90 and 0.85 for the observers, indicating good ability to predict the occurrence of errors. This tool could potentially be used to identify propagated contours that are likely to be incorrect, acting as a flag for manual review of these contours. This would make contour propagation more efficient, facilitating the routine implementation of adaptive radiotherapy.

A dosimetric phantom study of thoracic radiotherapy based on three-dimensional modeling of mediastinal lymph nodes

PubMed Central

Zhang, Ji-Bin; Zhao, Li-Rong; Cui, Tian-Xiang; Chen, Xie-Wan; Yang, Qiao; Zhou, Yi-Bing; Chen, Zheng-Tang; Zhang, Shao-Xiang; Sun, Jian-Guo

2018-01-01

The aim of the present study was to investigate the optimal strategy and dosimetric measurement of thoracic radiotherapy based on three-dimensional (3D) modeling of mediastinal lymph nodes (MLNs). A 3D model of MLNs was constructed from a Chinese Visible Human female dataset. Image registration and fusion between reconstructed MLNs and original chest computed tomography (CT) images was conducted in the Eclipse™ treatment planning system (TPS). There were three plans, including 3D conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT), which were designed based on 10 cases of simulated lung lesions (SLLs) and MLNs. The quality of these plans was evaluated via examining indexes, including conformity index (CI), homogeneity index and clinical target volume (CTV) coverage. Dose-volume histogram analysis was performed on SLL, MLNs and organs at risk (OARs). A Chengdu Dosimetric Phantom (CDP) was then drilled at specific MLNs according to 20 patients with thoracic tumors and of a medium-build. These plans were repeated on fused MLNs and CDP CT images in the Eclipse™ TPS. Radiation doses at the SLLs and MLNs of the CDP were measured and compared with calculated doses. The established 3D MLN model demonstrated the spatial location of MLNs and adjacent structures. Precise image registration and fusion were conducted between reconstructed MLNs and the original chest CT or CDP CT images. IMRT demonstrated greater values in CI, CTV coverage and OAR (lungs and spinal cord) protection, compared with 3D-CRT and VMAT (P<0.05). The deviation between the measured and calculated doses was within ± 10% at SLL, and at the 2R and 7th MLN stations. In conclusion, the 3D MLN model can benefit plan optimization and dosimetric measurement of thoracic radiotherapy, and when combined with CDP, it may provide a tool for clinical dosimetric monitoring. PMID:29556300

SU-E-J-78: Adaptive Planning Workflow in a Pencil Beam Scanning Proton Therapy Center

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blakey, M; Price, S; Robison, B

Purpose: The susceptibility of proton therapy to changes in patient setup and anatomy necessitates an adaptive planning process. With the right planning tools and clinical workflow, an adaptive plan can be created in a timely manner without adding significant workload to the treatment planning staff. Methods: In our center, a weekly QA CT is performed on most patients to assess setup, anatomy change, and tumor response. The QA CT is fused to the treatment planning CT, the contours are transferred via deformable registration, and the plan dose is recalculated on the QA CT. A physicist assesses the dose distribution, andmore » an adaptive plan is requested based on tumor coverage or OAR dose changes. After the physician confirms or alters the deformed contours, a dosimetrist develops an adaptive plan using our TPS adaptation module. The plan is assessed for robustness and is then reviewed by the physician. Patient QA is performed within three days following the first adapted treatment. Results: Of the patients who received QA CTs, 19% required at least one adaptive plan (18.5% H&N, 18.5% brain, 11.1% breast, 14.8% chestwall, 14.8% lung, 18.5% pelvis and 3.8% abdomen). Of these patients, 14% went on a break, while the remainder was treated with the previous plan during the re-planning process. Adaptive plans were performed based on tumor shrinkage, anatomy change or positioning uncertainties for 37.9%, 44.8%, and 17.3% of the patients, respectively. On average, 3 full days are required between the QA CT and the first adapted plan treatment. Conclusion: Adaptive planning is a crucial component of proton therapy and should be applied to any site when the QA CT shows significant deviation from the plan. With an efficient workflow, an adaptive plan can be applied without delaying patient treatment or burdening the dosimetry and medical physics team.« less

TU-H-CAMPUS-JeP2-01: Inter-Observer Delineation Comparison of Visible Glandular Breast Tissue On Magnetic Resonance Imaging and Computed Tomography (prone and Supine)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pogson, EM; University of Wollongong, Wollongong, NSW; Liverpool and Macarthur Cancer Therapy Centres, Liverpool, NSW

2016-06-15

Purpose: Breast cancers predominantly arise from Glandular Breast Tissue (GBT). If the GBT can be treated effectively post-operatively utilising radiotherapy this may be adequate volumetric coverage for adjuvant breast radiotherapy. Adequate imaging of the GBT is necessary and will be assessed between MRI and CT modalities. GBT visualisation is acknowledged to be qualitatively superior on Magnetic Resonance Image (MRI) compared to Computed Tomography (CT), the current radiotherapy imaging standard, however this has not been quantitatively assessed. For radiotherapy purposes it is important that any treatment volume can be consistently defined between observers. This study investigates the consistency of CT andmore » MRI GBT contours for potential radiotherapy planning. Methods: Ten experts (9 breast radiation oncologists and 1 radiologist) contoured the extent of the visible GBT for 33 patients on MRI and CT (both without contrast), which was performed according to a contouring guideline in supine and prone patient positions. The GBT volume was not a conventional whole breast radiotherapy planning volume, but rather the extent of GBT that was indicated from the CT or MR imaging. Volumes were compared utilizing the dice similarity coefficient (DSC), kappa statistic, and Hausdorff Distances (HDs) to ascertain the modality that was most consistently volumed. Results: The inter-observer concordance was of substantial agreement (kappa above 0.6) for the CT supine, CT prone, MRI supine and MRI prone datasets. The MRI GBT volumes were larger than the CT GBT volumes (p<0.001). Inter-observer conformity was higher for CT than MRI, although the magnitude of this difference was small (VOI<0.04). Conformity between modalities (CT and MRI) was in agreement for both prone and supine, DSC=0.75. Prone GBT volumes were larger than supine for both MRI and CT. Conclusion: MRI improves the extent of GBT delineation. The role of MRI guided, GBT-targeted radiotherapy requires investigation in a clinical trial. This work was supported by a grant number APP1033237 from Cancer Australia and the National Breast Cancer Foundation.« less

SU-F-T-252: An Investigation of Gamma Knife Frame Definition Error When Using a Pre-Planning Workflow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, P

Purpose: To determine causal factors related to high frame definition error when treating GK patients using a pre-planning workflow. Methods: 160 cases were retrospectively reviewed. All patients received treatment using a pre-planning workflow whereby stereotactic coordinates are determined from a CT scan acquired after framing using a fiducial box. The planning software automatically detects the fiducials and compares their location to expected values based on the rigid design of the fiducial system. Any difference is reported as mean and maximum frame definition error. The manufacturer recommends these values be less than 1.0 mm and 1.5 mm. In this study, framemore » definition error was analyzed in comparison with a variety of factors including which neurosurgeon/oncologist/physicist was involved with the procedure, number of post used during framing (3 or 4), type of lesion, and which CT scanner was utilized for acquisition. An analysis of variance (ANOVA) approach was used to statistically evaluate the data and determine causal factors related to instances of high frame definition error. Results: Two factors were identified as significant: number of post (p=0.0003) and CT scanner (p=0.0001). Further analysis showed that one of the four scanners was significantly different than the others. This diagnostic scanner was identified as an older model with localization lasers not tightly calibrated. The average value for maximum frame definition error using this scanner was 1.48 mm (4 posts) and 1.75 mm (3 posts). For the other scanners this value was 1.13 mm (4 posts) and 1.40 mm (3 posts). Conclusion: In utilizing a pre-planning workflow the choice of CT scanner matters. Any scanner utilized for GK should undergo routine QA at a level appropriate for radiation oncology. In terms of 3 vs 4 post, it is hypothesized that three posts provide less stability during CT acquisition. This will be tested in future work.« less

A multimodality segmentation framework for automatic target delineation in head and neck radiotherapy.

PubMed

Yang, Jinzhong; Beadle, Beth M; Garden, Adam S; Schwartz, David L; Aristophanous, Michalis

2015-09-01

To develop an automatic segmentation algorithm integrating imaging information from computed tomography (CT), positron emission tomography (PET), and magnetic resonance imaging (MRI) to delineate target volume in head and neck cancer radiotherapy. Eleven patients with unresectable disease at the tonsil or base of tongue who underwent MRI, CT, and PET/CT within two months before the start of radiotherapy or chemoradiotherapy were recruited for the study. For each patient, PET/CT and T1-weighted contrast MRI scans were first registered to the planning CT using deformable and rigid registration, respectively, to resample the PET and magnetic resonance (MR) images to the planning CT space. A binary mask was manually defined to identify the tumor area. The resampled PET and MR images, the planning CT image, and the binary mask were fed into the automatic segmentation algorithm for target delineation. The algorithm was based on a multichannel Gaussian mixture model and solved using an expectation-maximization algorithm with Markov random fields. To evaluate the algorithm, we compared the multichannel autosegmentation with an autosegmentation method using only PET images. The physician-defined gross tumor volume (GTV) was used as the "ground truth" for quantitative evaluation. The median multichannel segmented GTV of the primary tumor was 15.7 cm(3) (range, 6.6-44.3 cm(3)), while the PET segmented GTV was 10.2 cm(3) (range, 2.8-45.1 cm(3)). The median physician-defined GTV was 22.1 cm(3) (range, 4.2-38.4 cm(3)). The median difference between the multichannel segmented and physician-defined GTVs was -10.7%, not showing a statistically significant difference (p-value = 0.43). However, the median difference between the PET segmented and physician-defined GTVs was -19.2%, showing a statistically significant difference (p-value =0.0037). The median Dice similarity coefficient between the multichannel segmented and physician-defined GTVs was 0.75 (range, 0.55-0.84), and the median sensitivity and positive predictive value between them were 0.76 and 0.81, respectively. The authors developed an automated multimodality segmentation algorithm for tumor volume delineation and validated this algorithm for head and neck cancer radiotherapy. The multichannel segmented GTV agreed well with the physician-defined GTV. The authors expect that their algorithm will improve the accuracy and consistency in target definition for radiotherapy.

A navigation system for percutaneous needle interventions based on PET/CT images: design, workflow and error analysis of soft tissue and bone punctures.

PubMed

Oliveira-Santos, Thiago; Klaeser, Bernd; Weitzel, Thilo; Krause, Thomas; Nolte, Lutz-Peter; Peterhans, Matthias; Weber, Stefan

2011-01-01

Percutaneous needle intervention based on PET/CT images is effective, but exposes the patient to unnecessary radiation due to the increased number of CT scans required. Computer assisted intervention can reduce the number of scans, but requires handling, matching and visualization of two different datasets. While one dataset is used for target definition according to metabolism, the other is used for instrument guidance according to anatomical structures. No navigation systems capable of handling such data and performing PET/CT image-based procedures while following clinically approved protocols for oncologic percutaneous interventions are available. The need for such systems is emphasized in scenarios where the target can be located in different types of tissue such as bone and soft tissue. These two tissues require different clinical protocols for puncturing and may therefore give rise to different problems during the navigated intervention. Studies comparing the performance of navigated needle interventions targeting lesions located in these two types of tissue are not often found in the literature. Hence, this paper presents an optical navigation system for percutaneous needle interventions based on PET/CT images. The system provides viewers for guiding the physician to the target with real-time visualization of PET/CT datasets, and is able to handle targets located in both bone and soft tissue. The navigation system and the required clinical workflow were designed taking into consideration clinical protocols and requirements, and the system is thus operable by a single person, even during transition to the sterile phase. Both the system and the workflow were evaluated in an initial set of experiments simulating 41 lesions (23 located in bone tissue and 18 in soft tissue) in swine cadavers. We also measured and decomposed the overall system error into distinct error sources, which allowed for the identification of particularities involved in the process as well as highlighting the differences between bone and soft tissue punctures. An overall average error of 4.23 mm and 3.07 mm for bone and soft tissue punctures, respectively, demonstrated the feasibility of using this system for such interventions. The proposed system workflow was shown to be effective in separating the preparation from the sterile phase, as well as in keeping the system manageable by a single operator. Among the distinct sources of error, the user error based on the system accuracy (defined as the distance from the planned target to the actual needle tip) appeared to be the most significant. Bone punctures showed higher user error, whereas soft tissue punctures showed higher tissue deformation error.

MR Imaging Based Treatment Planning for Radiotherapy of Prostate Cancer

DTIC Science & Technology

2008-02-01

Radiotherapy, MR-based treatment planning, dosimetry, Monte Carlo dose verification, Prostate Cancer, MRI -based DRRs 16. SECURITY CLASSIFICATION...AcQPlan system Version 5 was used for the study , which is capable of performing dose calculation on both CT and MRI . A four field 3D conformal planning...prostate motion studies for 3DCRT and IMRT of prostate cancer; (2) to investigate and improve the accuracy of MRI -based treatment planning dose calculation

How I do it-optimizing radiofrequency ablation in spinal metastases using iCT and navigation.

PubMed

Kavakebi, Pujan; Freyschlag, C F; Thomé, C

2017-10-01

Exact positioning of the radiofrequency ablation (RFA) probe for tumor treatment under fluoroscopic guidance can be difficult because of potentially small inaccessible lesions and the radiation dose to the medical staff in RFA. In addition, vertebroplasty (VP) can be significantly high. Description and workflow of RFA in spinal metastasis using iCT (intraoperative computed tomography) and 3D-navigation-based probe placement followed by VP. RFA and VP can be successfully combined with iCT-based navigation, which leads to a reduction of radiation to the staff and optimal probe positioning due to 3D navigation.

A new methodological approach for PET implementation in radiotherapy treatment planning.

PubMed

Bellan, Elena; Ferretti, Alice; Capirci, Carlo; Grassetto, Gaia; Gava, Marcello; Chondrogiannis, Sotirios; Virdis, Graziella; Marzola, Maria Cristina; Massaro, Arianna; Rubello, Domenico; Nibale, Otello

2012-05-01

In this paper, a new methodological approach to using PET information in radiotherapy treatment planning has been discussed. Computed tomography (CT) represents the primary modality to plan personalized radiation treatment, because it provides the basic electron density map for correct dose calculation. If PET scanning is also performed it is typically coregistered with the CT study. This operation can be executed automatically by a hybrid PET/CT scanner or, if the PET and CT imaging sets have been acquired through different equipment, by a dedicated module of the radiotherapy treatment planning system. Both approaches have some disadvantages: in the first case, the bore of a PET/CT system generally used in clinical practice often does not allow the use of certain bulky devices for patient immobilization in radiotherapy, whereas in the second case the result could be affected by limitations in window/level visualization of two different image modalities, and the displayed PET volumes can appear not to be related to the actual uptake into the patient. To overcome these problems, at our centre a specific procedure has been studied and tested in 30 patients, allowing good results of precision in the target contouring to be obtained. The process consists of segmentation of the biological target volume by a dedicated PET/CT console and its export to a dedicated radiotherapy system, where an image registration between the CT images acquired by the PET/CT scanner and a large-bore CT is performed. The planning target volume is contoured only on the large-bore CT and is used for virtual simulation, to individuate permanent skin markers on the patient.

Total Navigation in Spine Surgery; A Concise Guide to Eliminate Fluoroscopy Using a Portable Intraoperative Computed Tomography 3-Dimensional Navigation System.

PubMed

Navarro-Ramirez, Rodrigo; Lang, Gernot; Lian, Xiaofeng; Berlin, Connor; Janssen, Insa; Jada, Ajit; Alimi, Marjan; Härtl, Roger

2017-04-01

Portable intraoperative computed tomography (iCT) with integrated 3-dimensional navigation (NAV) offers new opportunities for more precise navigation in spinal surgery, eliminates radiation exposure for the surgical team, and accelerates surgical workflows. We present the concept of "total navigation" using iCT NAV in spinal surgery. Therefore, we propose a step-by-step guideline demonstrating how total navigation can eliminate fluoroscopy with time-efficient workflows integrating iCT NAV into daily practice. A prospective study was conducted on collected data from patients undergoing iCT NAV-guided spine surgery. Number of scans, radiation exposure, and workflow of iCT NAV (e.g., instrumentation, cage placement, localization) were documented. Finally, the accuracy of pedicle screws and time for instrumentation were determined. iCT NAV was successfully performed in 117 cases for various indications and in all regions of the spine. More than half (61%) of cases were performed in a minimally invasive manner. Navigation was used for skin incision, localization of index level, and verification of implant position. iCT NAV was used to evaluate neural decompression achieved in spinal fusion surgeries. Total navigation eliminates fluoroscopy in 75%, thus reducing staff radiation exposure entirely. The average times for iCT NAV setup and pedicle screw insertion were 12.1 and 3.1 minutes, respectively, achieving a pedicle screw accuracy of 99%. Total navigation makes spine surgery safer and more accurate, and it enhances efficient and reproducible workflows. Fluoroscopy and radiation exposure for the surgical staff can be eliminated in the majority of cases. Copyright © 2017 Elsevier Inc. All rights reserved.

SU-G-JeP3-05: Geometry Based Transperineal Ultrasound Probe Positioning for Image Guided Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Camps, S; With, P de; Verhaegen, F

2016-06-15

Purpose: The use of ultrasound (US) imaging in radiotherapy is not widespread, primarily due to the need for skilled operators performing the scans. Automation of probe positioning has the potential to remove this need and minimize operator dependence. We introduce an algorithm for obtaining a US probe position that allows good anatomical structure visualization based on clinical requirements. The first application is on 4D transperineal US images of prostate cancer patients. Methods: The algorithm calculates the probe position and orientation using anatomical information provided by a reference CT scan, always available in radiotherapy workflows. As initial test, we apply themore » algorithm on a CIRS pelvic US phantom to obtain a set of possible probe positions. Subsequently, five of these positions are randomly chosen and used to acquire actual US volumes of the phantom. Visual inspection of these volumes reveal if the whole prostate, and adjacent edges of bladder and rectum are fully visualized, as clinically required. In addition, structure positions on the acquired US volumes are compared to predictions of the algorithm. Results: All acquired volumes fulfill the clinical requirements as specified in the previous section. Preliminary quantitative evaluation was performed on thirty consecutive slices of two volumes, on which the structures are easily recognizable. The mean absolute distances (MAD) between actual anatomical structure positions and positions predicted by the algorithm were calculated. This resulted in MAD of 2.4±0.4 mm for prostate, 3.2±0.9 mm for bladder and 3.3±1.3 mm for rectum. Conclusion: Visual inspection and quantitative evaluation show that the algorithm is able to propose probe positions that fulfill all clinical requirements. The obtained MAD is on average 2.9 mm. However, during evaluation we assumed no errors in structure segmentation and probe positioning. In future steps, accurate estimation of these errors will allow for better evaluation of the achieved accuracy.« less

Contrast-Enhanced [{sup 18}F]fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography for Staging and Radiotherapy Planning in Patients With Anal Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bannas, Peter, E-mail: p.bannas@uke.de; Weber, Christoph; Adam, Gerhard

2011-10-01

Purpose: The practice of surgical staging and treatment of anal cancer has been replaced by noninvasive staging and combined modality therapy. For appropriate patient management, accurate lymph node staging is crucial. The present study evaluated the feasibility and diagnostic accuracy of contrast-enhanced [{sup 18}F]fluoro-2-deoxy-D-glucose ([{sup 18}F]FDG)-positron emission tomography/computed tomography (PET/CT) for staging and radiotherapy planning of anal cancer. Methods and Materials: A total of 22 consecutive patients (median age, 61 years old) with anal cancer underwent complete staging evaluation including physical examination, biopsy of the primary tumor, and contrast-enhanced (ce)-PET/CT. Patients were positioned as they would be for their subsequentmore » radiotherapy. PET and CT images were evaluated independently for detectability and localization of the primary tumor, pelvic and inguinal lymph nodes, and distant metastasis. The stage, determined by CT or PET alone, and the proposed therapy planning were compared with the stage and management determined by ce-PET/CT. Data from ce-PET/CT were used for radiotherapy planning. Results: ce-PET/CT revealed locoregional lymph node metastasis in 11 of 22 patients (50%). After simultaneous reading of PET and CT data sets by experienced observers, 3 patients (14%) were found to have sites of disease not seen on CT that were identified on PET. Two patients had sites of disease not seen on PET that were identified on CT. In summary, 2 patients were upstaged, and 4 patients were downstaged due to ce-PET/CT. However, radiotherapy fields were changed due to the results from ce-PET/CT in 23% of cases compared to CT or PET results alone. Conclusions: ce-PET/CT is superior to PET or CT alone for staging of anal cancer, with significant impact on therapy planning.« less

Metal artifact reduction through MVCBCT and kVCT in radiotherapy

NASA Astrophysics Data System (ADS)

Liugang, Gao; Hongfei, Sun; Xinye, Ni; Mingming, Fang; Zheng, Cao; Tao, Lin

2016-11-01

This study proposes a new method for removal of metal artifacts from megavoltage cone beam computed tomography (MVCBCT) and kilovoltage CT (kVCT) images. Both images were combined to obtain prior image, which was forward projected to obtain surrogate data and replace metal trace in the uncorrected kVCT image. The corrected image was then reconstructed through filtered back projection. A similar radiotherapy plan was designed using the theoretical CT image, the uncorrected kVCT image, and the corrected image. The corrected images removed most metal artifacts, and the CT values were accurate. The corrected image also distinguished the hollow circular hole at the center of the metal. The uncorrected kVCT image did not display the internal structure of the metal, and the hole was misclassified as metal portion. Dose distribution calculated based on the corrected image was similar to that based on the theoretical CT image. The calculated dose distribution also evidently differed between the uncorrected kVCT image and the theoretical CT image. The use of the combined kVCT and MVCBCT to obtain the prior image can distinctly improve the quality of CT images containing large metal implants.

4D-Listmode-PET-CT and 4D-CT for optimizing PTV margins in gastric lymphoma : Determination of intra- and interfractional gastric motion.

PubMed

Reinartz, Gabriele; Haverkamp, Uwe; Wullenkord, Ramona; Lehrich, Philipp; Kriz, Jan; Büther, Florian; Schäfers, Klaus; Schäfers, Michael; Eich, Hans Theodor

2016-05-01

New imaging protocols for radiotherapy in localized gastric lymphoma were evaluated to optimize planning target volume (PTV) margin and determine intra-/interfractional variation of the stomach. Imaging of 6 patients was explored prospectively. Intensity-modulated radiotherapy (IMRT) planning was based on 4D/3D imaging of computed tomography (CT) and positron-emission tomography (PET)-CT. Static and motion gross tumor volume (sGTV and mGTV, respectively) were distinguished by defining GTV (empty stomach), clinical target volume (CTV = GTV + 5 mm margin), PTV (GTV + 10/15/20/25 mm margins)  plus paraaortic lymph nodes and proximal duodenum. Overlap of 4D-Listmode-PET-based mCTV with 3D-CT-based PTV (increasing margins) and V95/D95 of mCTV were evaluated. Gastric shifts were determined using online cone-beam CT. Dose contribution to organs at risk was assessed. The 4D data demonstrate considerable intra-/interfractional variation of the stomach, especially along the vertical axis. Conventional 3D-CT planning utilizing advancing PTV margins of 10/15/20/25 mm resulted in rising dose coverage of mCTV (4D-Listmode-PET-Summation-CT) and rising D95 and V95 of mCTV. A PTV margin of 15 mm was adequate in 3 of 6 patients, a PTV margin of 20 mm was adequate in 4 of 6 patients, and a PTV margin of 25 mm was adequate in 5 of 6 patients. IMRT planning based on 4D-PET-CT/4D-CT together with online cone-beam CT is advisable to individualize the PTV margin and optimize target coverage in gastric lymphoma.

Audit of radiation dose delivered in time-resolved four-dimensional computed tomography in a radiotherapy department.

PubMed

Hubbard, Patricia; Callahan, Jason; Cramb, Jim; Budd, Ray; Kron, Tomas

2015-06-01

To review the dose delivered to patients in time-resolved computed tomography (4D CT) used for radiotherapy treatment planning. 4D CT is used at Peter MacCallum Cancer Centre since July 2007 for radiotherapy treatment planning using a Philips Brilliance Wide Bore CT scanner (16 slice, helical 4D CT acquisition). All scans are performed at 140 kVp and reconstructed in 10 datasets for different phases of the breathing cycle. Dose records were analysed retrospectively for 387 patients who underwent 4D CT procedures between 2007 and 2013. A total of 444 4D CT scans were acquired with the majority of them (342) being for lung cancer radiotherapy. Volume CT dose index (CTDIvol) as recorded over this period was fairly constant at approximately 20 mGy for adults. The CTDI for 4D CT for lung cancers of 19.6 ± 9.3 mGy (n = 168, mean ± 1SD) was found to be 63% higher than CTDIs for conventional CT scans for lung patients that were acquired in the same period (CTDIvol 12 ± 4 mGy, sample of n = 25). CTDI and dose length product (DLP) increased with increasing field of view; however, no significant difference between DLPs for different indications (breast, kidney, liver and lung) could be found. Breathing parameters such as breathing rate or pattern did not affect dose. 4D CT scans can be acquired for radiotherapy treatment planning with a dose less than twice the one required for conventional CT scanning. © 2015 The Royal Australian and New Zealand College of Radiologists.

Automating the expert consensus paradigm for robust lung tissue classification

NASA Astrophysics Data System (ADS)

Rajagopalan, Srinivasan; Karwoski, Ronald A.; Raghunath, Sushravya; Bartholmai, Brian J.; Robb, Richard A.

2012-03-01

Clinicians confirm the efficacy of dynamic multidisciplinary interactions in diagnosing Lung disease/wellness from CT scans. However, routine clinical practice cannot readily accomodate such interactions. Current schemes for automating lung tissue classification are based on a single elusive disease differentiating metric; this undermines their reliability in routine diagnosis. We propose a computational workflow that uses a collection (#: 15) of probability density functions (pdf)-based similarity metrics to automatically cluster pattern-specific (#patterns: 5) volumes of interest (#VOI: 976) extracted from the lung CT scans of 14 patients. The resultant clusters are refined for intra-partition compactness and subsequently aggregated into a super cluster using a cluster ensemble technique. The super clusters were validated against the consensus agreement of four clinical experts. The aggregations correlated strongly with expert consensus. By effectively mimicking the expertise of physicians, the proposed workflow could make automation of lung tissue classification a clinical reality.

Tracking Organs Composed of One or Multiple Regions Using Geodesic Active Region Models

NASA Astrophysics Data System (ADS)

Martínez, A.; Jiménez, J. J.

In radiotherapy treatment it is very important to find out the target organs on the medical image sequence in order to determine and apply the proper dose. The techniques to achieve this goal can be classified into extrinsic and intrinsic. Intrinsic techniques only use image processing with medical images associated to the radiotherapy Radiotherapy treatment, as we deal in this chapter. To accurately perform this organ tracking it is necessary to find out segmentation and tracking models that were able to be applied to several image modalities involved on a radiotherapy session (CT CT See Modality , MRI Magnetic resoance imaging , etc.). The movements of the organs are mainly affected by two factors: breathing and involuntary movements associated with the internal organs or patient positioning. Among the several alternatives to track the organs of interest, a model based on geodesic active regions is proposed. This model has been tested over CT Computed tomography images from the pelvic, cardiac, and thoracic area. A new model for the segmentation of organs composed by more than one region is proposed.

SU-E-J-159: Analysis of Total Imaging Uncertainty in Respiratory-Gated Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suzuki, J; Okuda, T; Sakaino, S

Purpose: In respiratory-gated radiotherapy, the gating phase during treatment delivery needs to coincide with the corresponding phase determined during the treatment plan. However, because radiotherapy is performed based on the image obtained for the treatment plan, the time delay, motion artifact, volume effect, and resolution in the images are uncertain. Thus, imaging uncertainty is the most basic factor that affects the localization accuracy. Therefore, these uncertainties should be analyzed. This study aims to analyze the total imaging uncertainty in respiratory-gated radiotherapy. Methods: Two factors of imaging uncertainties related to respiratory-gated radiotherapy were analyzed. First, CT image was used to determinemore » the target volume and 4D treatment planning for the Varian Realtime Position Management (RPM) system. Second, an X-ray image was acquired for image-guided radiotherapy (IGRT) for the BrainLAB ExacTrac system. These factors were measured using a respiratory gating phantom. The conditions applied during phantom operation were as follows: respiratory wave form, sine curve; respiratory cycle, 4 s; phantom target motion amplitude, 10, 20, and 29 mm (which is maximum phantom longitudinal motion). The target and cylindrical marker implanted in the phantom coverage of the CT images was measured and compared with the theoretically calculated coverage from the phantom motion. The theoretical position of the cylindrical marker implanted in the phantom was compared with that acquired from the X-ray image. The total imaging uncertainty was analyzed from these two factors. Results: In the CT image, the uncertainty between the target and cylindrical marker’s actual coverage and the coverage of CT images was 1.19 mm and 2.50mm, respectively. In the Xray image, the uncertainty was 0.39 mm. The total imaging uncertainty from the two factors was 1.62mm. Conclusion: The total imaging uncertainty in respiratory-gated radiotherapy was clinically acceptable. However, an internal margin should be added to account for the total imaging uncertainty.« less

Quality Assurance Assessment of Diagnostic and Radiation Therapy–Simulation CT Image Registration for Head and Neck Radiation Therapy: Anatomic Region of Interest–based Comparison of Rigid and Deformable Algorithms

PubMed Central

Mohamed, Abdallah S. R.; Ruangskul, Manee-Naad; Awan, Musaddiq J.; Baron, Charles A.; Kalpathy-Cramer, Jayashree; Castillo, Richard; Castillo, Edward; Guerrero, Thomas M.; Kocak-Uzel, Esengul; Yang, Jinzhong; Court, Laurence E.; Kantor, Michael E.; Gunn, G. Brandon; Colen, Rivka R.; Frank, Steven J.; Garden, Adam S.; Rosenthal, David I.

2015-01-01

Purpose To develop a quality assurance (QA) workflow by using a robust, curated, manually segmented anatomic region-of-interest (ROI) library as a benchmark for quantitative assessment of different image registration techniques used for head and neck radiation therapy–simulation computed tomography (CT) with diagnostic CT coregistration. Materials and Methods Radiation therapy–simulation CT images and diagnostic CT images in 20 patients with head and neck squamous cell carcinoma treated with curative-intent intensity-modulated radiation therapy between August 2011 and May 2012 were retrospectively retrieved with institutional review board approval. Sixty-eight reference anatomic ROIs with gross tumor and nodal targets were then manually contoured on images from each examination. Diagnostic CT images were registered with simulation CT images rigidly and by using four deformable image registration (DIR) algorithms: atlas based, B-spline, demons, and optical flow. The resultant deformed ROIs were compared with manually contoured reference ROIs by using similarity coefficient metrics (ie, Dice similarity coefficient) and surface distance metrics (ie, 95% maximum Hausdorff distance). The nonparametric Steel test with control was used to compare different DIR algorithms with rigid image registration (RIR) by using the post hoc Wilcoxon signed-rank test for stratified metric comparison. Results A total of 2720 anatomic and 50 tumor and nodal ROIs were delineated. All DIR algorithms showed improved performance over RIR for anatomic and target ROI conformance, as shown for most comparison metrics (Steel test, P < .008 after Bonferroni correction). The performance of different algorithms varied substantially with stratification by specific anatomic structures or category and simulation CT section thickness. Conclusion Development of a formal ROI-based QA workflow for registration assessment demonstrated improved performance with DIR techniques over RIR. After QA, DIR implementation should be the standard for head and neck diagnostic CT and simulation CT allineation, especially for target delineation. © RSNA, 2014 Online supplemental material is available for this article. PMID:25380454

Driving CT developments the last mile: case examples of successful and somewhat less successful translations into clinical practice

NASA Astrophysics Data System (ADS)

Sodickson, Aaron D.

2017-03-01

CT technology has advanced rapidly in recent years, yet not all innovations translate readily into clinical practice. Technology advances must meet certain key requirements to make it into routine use: They must provide a well-defined clinical benefit. They must be easy to use and integrate readily into existing workflows, or better still, further streamline these workflows. These requirements heavily favor fully integrated or automated solutions that remove the human factor and provide a reproducible output independent of operator skill level. Further, to achieve these aims, collaboration with the ultimate end users is needed as early as possible in the development cycle, not just at the point of product testing. Technology innovators are encouraged to engage such collaborators even at early stages of feature or product definition. This manuscript highlights these concepts through exploration of challenging areas in CT imaging in an Emergency Department setting. Technique optimization for pulmonary embolus CT is described as an example of successful integration of multiple advances in radiation dose reduction and imaging speed. The typical workflow of a trauma "pan-scan" (incorporating scans from head through pelvis) is described to highlight workflow challenges and opportunities for improvement. Finally, Dual Energy CT is discussed to highlight the undeniable clinical value of the material characterization it provides, yet also its surprisingly slow integration into routine use beyond early adopters.

Assessment of contrast enhanced respiration managed cone-beam CT for image guided radiotherapy of intrahepatic tumors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jensen, Nikolaj K. G., E-mail: nkyj@regionsjaelland.dk; Stewart, Errol; Imaging Research Lab, Robarts Research Institute, London, Ontario N6A 5B7

2014-05-15

Purpose: Contrast enhancement and respiration management are widely used during image acquisition for radiotherapy treatment planning of liver tumors along with respiration management at the treatment unit. However, neither respiration management nor intravenous contrast is commonly used during cone-beam CT (CBCT) image acquisition for alignment prior to radiotherapy. In this study, the authors investigate the potential gains of injecting an iodinated contrast agent in combination with respiration management during CBCT acquisition for liver tumor radiotherapy. Methods: Five rabbits with implanted liver tumors were subjected to CBCT with and without motion management and contrast injection. The acquired CBCT images were registeredmore » to the planning CT to determine alignment accuracy and dosimetric impact. The authors developed a simulation tool for simulating contrast-enhanced CBCT images from dynamic contrast enhanced CT imaging (DCE-CT) to determine optimal contrast injection protocols. The tool was validated against contrast-enhanced CBCT of the rabbit subjects and was used for five human patients diagnosed with hepatocellular carcinoma. Results: In the rabbit experiment, when neither motion management nor contrast was used, tumor centroid misalignment between planning image and CBCT was 9.2 mm. This was reduced to 2.8 mm when both techniques were employed. Tumors were not visualized in clinical CBCT images of human subjects. Simulated contrast-enhanced CBCT was found to improve tumor contrast in all subjects. Different patients were found to require different contrast injections to maximize tumor contrast. Conclusions: Based on the authors’ animal study, respiration managed contrast enhanced CBCT improves IGRT significantly. Contrast enhanced CBCT benefits from patient specific tracer kinetics determined from DCE-CT.« less

Evidence for the use PET for radiation therapy planning in patients with cervical cancer: a systematic review.

PubMed

Salem, A; Salem, A F; Al-Ibraheem, A; Lataifeh, I; Almousa, A; Jaradat, I

2011-01-01

In recent years, the role of positron emission tomography (PET) in the staging and management of gynecological cancers has been increasing. The aim of this study was to systematically review the role of PET in radiotherapy planning and brachytherapy treatment optimization in patients with cervical cancer. Systematic literature review. Systematic review of relevant literature addressing the utilization of PET and/or PET-computed tomography (CT) in external-beam radiotherapy planning and brachytherapy treatment optimization. We performed an extensive PubMed database search on 20 April 2011. Nineteen studies, including 759 patients, formed the basis of this systematic review. PET/ PET-CT is the most sensitive imaging modality for detecting nodal metastases in patients with cervical cancer and has been shown to impact external-beam radiotherapy planning by modifying the treatment field and customizing the radiation dose. This particularly applies to detection of previously uncovered para-aortic and inguinal nodal metastases. Furthermore, PET/ PET-CT guided intensity-modulated radiation therapy (IMRT) allows delivery of higher doses of radiation to the primary tumor, if brachytherapy is unsuitable, and to grossly involved nodal disease while minimizing treatment-related toxicity. PET/ PET-CT based brachytherapy optimization allows improved tumor-volume dose distribution and detailed 3D dosimetric evaluation of risk organs. Sequential PET/ PET-CT imaging performed during the course of brachytherapy form the basis of “adaptive” brachytherapy in cervical cancer. This review demonstrates the effectiveness of pretreatment PET/ PET-CT in cervical cancer patients treated by radiotherapy. Further prospective studies are required to define the group of patients who would benefit the most from this procedure.

18F-Choline PET/CT scan in staging and biochemical recurrence in prostate cancer patients: Changes in classification and radiotherapy planning.

PubMed

Cardona Arboniés, J; Rodríguez Alfonso, B; Mucientes Rasilla, J; Martínez Ballesteros, C; Zapata Paz, I; Prieto Soriano, A; Carballido Rodriguez, J; Mitjavila Casanovas, M

To evaluate the role of the 18 F-Choline PET/CT in prostate cancer management when detecting distant disease in planning radiotherapy and staging and to evaluate the therapy changes guided by PET/TC results. A retrospective evaluation was performed on 18 F-Choline PET/CT scans of patients with prostate cancer. Staging and planning radiotherapy scans were selected in patients with at least 9 months follow up. There was a total of 56 studies, 33 (58.93%) for staging, and 23 (41.07%) for planning radiotherapy. All scans were obtained using a hybrid PET/CT scanner. The PET/CT acquisition protocol consisted of a dual-phase procedure after the administration of an intravenous injection of 296-370MBq of 18 F-Choline. There were 43 out of 56 (76.8%) scans considered as positive, and 13 (23.2%) were negative. The TNM staging was changed in 13 (23.2%) scans. The PET/CT findings ruled out distant disease in 4 out of 13 scans, and unknown distant disease was detected in 9 (69.3%) scans. 18 F-Choline PET/CT is a useful technique for detecting unknown distant disease in prostate cancer when staging and planning radiotherapy. The inclusion of 18 F-choline PET/CT should be considered in prostate cancer management protocols. Copyright © 2017 Elsevier España, S.L.U. y SEMNIM. All rights reserved.

Biomechanical deformable image registration of longitudinal lung CT images using vessel information

NASA Astrophysics Data System (ADS)

Cazoulat, Guillaume; Owen, Dawn; Matuszak, Martha M.; Balter, James M.; Brock, Kristy K.

2016-07-01

Spatial correlation of lung tissue across longitudinal images, as the patient responds to treatment, is a critical step in adaptive radiotherapy. The goal of this work is to expand a biomechanical model-based deformable registration algorithm (Morfeus) to achieve accurate registration in the presence of significant anatomical changes. Six lung cancer patients previously treated with conventionally fractionated radiotherapy were retrospectively evaluated. Exhale CT scans were obtained at treatment planning and following three weeks of treatment. For each patient, the planning CT was registered to the follow-up CT using Morfeus, a biomechanical model-based deformable registration algorithm. To model the complex response of the lung, an extension to Morfeus has been developed: an initial deformation was estimated with Morfeus consisting of boundary conditions on the chest wall and incorporating a sliding interface with the lungs. It was hypothesized that the addition of boundary conditions based on vessel tree matching would provide a robust reduction of the residual registration error. To achieve this, the vessel trees were segmented on the two images by thresholding a vesselness image based on the Hessian matrix’s eigenvalues. For each point on the reference vessel tree centerline, the displacement vector was estimated by applying a variant of the Demons registration algorithm between the planning CT and the deformed follow-up CT. An expert independently identified corresponding landmarks well distributed in the lung to compute target registration errors (TRE). The TRE was: 5.8+/- 2.9 , 3.4+/- 2.3 and 1.6+/- 1.3 mm after rigid registration, Morfeus and Morfeus with boundary conditions on the vessel tree, respectively. In conclusion, the addition of boundary conditions on the vessels significantly improved the accuracy in modeling the response of the lung and tumor over the course of radiotherapy. Minimizing and modeling these geometrical uncertainties will enable future plan adaptation strategies.

Intra-patient semi-automated segmentation of the cervix-uterus in CT-images for adaptive radiotherapy of cervical cancer

NASA Astrophysics Data System (ADS)

Luiza Bondar, M.; Hoogeman, Mischa; Schillemans, Wilco; Heijmen, Ben

2013-08-01

For online adaptive radiotherapy of cervical cancer, fast and accurate image segmentation is required to facilitate daily treatment adaptation. Our aim was twofold: (1) to test and compare three intra-patient automated segmentation methods for the cervix-uterus structure in CT-images and (2) to improve the segmentation accuracy by including prior knowledge on the daily bladder volume or on the daily coordinates of implanted fiducial markers. The tested methods were: shape deformation (SD) and atlas-based segmentation (ABAS) using two non-rigid registration methods: demons and a hierarchical algorithm. Tests on 102 CT-scans of 13 patients demonstrated that the segmentation accuracy significantly increased by including the bladder volume predicted with a simple 1D model based on a manually defined bladder top. Moreover, manually identified implanted fiducial markers significantly improved the accuracy of the SD method. For patients with large cervix-uterus volume regression, the use of CT-data acquired toward the end of the treatment was required to improve segmentation accuracy. Including prior knowledge, the segmentation results of SD (Dice similarity coefficient 85 ± 6%, error margin 2.2 ± 2.3 mm, average time around 1 min) and of ABAS using hierarchical non-rigid registration (Dice 82 ± 10%, error margin 3.1 ± 2.3 mm, average time around 30 s) support their use for image guided online adaptive radiotherapy of cervical cancer.

Intra-patient semi-automated segmentation of the cervix-uterus in CT-images for adaptive radiotherapy of cervical cancer.

PubMed

Bondar, M Luiza; Hoogeman, Mischa; Schillemans, Wilco; Heijmen, Ben

2013-08-07

For online adaptive radiotherapy of cervical cancer, fast and accurate image segmentation is required to facilitate daily treatment adaptation. Our aim was twofold: (1) to test and compare three intra-patient automated segmentation methods for the cervix-uterus structure in CT-images and (2) to improve the segmentation accuracy by including prior knowledge on the daily bladder volume or on the daily coordinates of implanted fiducial markers. The tested methods were: shape deformation (SD) and atlas-based segmentation (ABAS) using two non-rigid registration methods: demons and a hierarchical algorithm. Tests on 102 CT-scans of 13 patients demonstrated that the segmentation accuracy significantly increased by including the bladder volume predicted with a simple 1D model based on a manually defined bladder top. Moreover, manually identified implanted fiducial markers significantly improved the accuracy of the SD method. For patients with large cervix-uterus volume regression, the use of CT-data acquired toward the end of the treatment was required to improve segmentation accuracy. Including prior knowledge, the segmentation results of SD (Dice similarity coefficient 85 ± 6%, error margin 2.2 ± 2.3 mm, average time around 1 min) and of ABAS using hierarchical non-rigid registration (Dice 82 ± 10%, error margin 3.1 ± 2.3 mm, average time around 30 s) support their use for image guided online adaptive radiotherapy of cervical cancer.

The Utility of PET/CT in the Planning of External Radiation Therapy for Prostate Cancer.

PubMed

Calais, Jeremie; Cao, Minsong; Nickols, Nicholas G

2018-04-01

Radiotherapy and radical prostatectomy are the definitive treatment options for patients with localized prostate cancer. A rising level of prostate-specific antigen after radical prostatectomy indicates prostate cancer recurrence, and these patients may still be cured with salvage radiotherapy. To maximize chance for cure, the irradiated volumes should completely encompass the extent of disease. Therefore, accurate estimation of the location of disease is critical for radiotherapy planning in both the definitive and the salvage settings. Current first-line imaging for prostate cancer has limited sensitivity for detection of disease both at initial staging and at biochemical recurrence. Integration of PET into routine evaluation of prostate cancer patients may improve both staging accuracy and radiotherapy planning. 18 F-FDG PET/CT is now routinely used in radiation planning for several cancer types. However, 18 F-FDG PET/CT has low sensitivity for prostate cancer. Additional PET probes evaluated in prostate cancer include 18 F-sodium fluoride, 11 C-acetate, 11 C- or 18 F-choline, 18 F-fluciclovine, and 68 Ga- or 18 F-labeled ligands that bind prostate-specific membrane antigen (PSMA). PSMA ligands appear to be the most sensitive and specific but have not yet received Food and Drug Administration New Drug Application approval for use in the United States. Retrospective and prospective investigations suggest a potential major impact of PET/CT on prostate radiation treatment planning. Prospective trials randomizing patients to routine radiotherapy planning versus PET/CT-aided planning may show meaningful clinical outcomes. Prospective clinical trials evaluating the addition of 18 F-fluciclovine PET/CT for planning of salvage radiotherapy with clinical endpoints are under way. Prospective trials evaluating the clinical impact of PSMA PET/CT on prostate radiation planning are indicated. © 2018 by the Society of Nuclear Medicine and Molecular Imaging.

The application of positron emission tomography/computed tomography in radiation treatment planning: effect on gross target volume definition and treatment management.

PubMed

Iğdem, S; Alço, G; Ercan, T; Unalan, B; Kara, B; Geceer, G; Akman, C; Zengin, F O; Atilla, S; Okkan, S

2010-04-01

To analyse the effect of the use of molecular imaging on gross target volume (GTV) definition and treatment management. Fifty patients with various solid tumours who underwent positron emission tomography (PET)/computed tomography (CT) simulation for radiotherapy planning from 2006 to 2008 were enrolled in this study. First, F-18 fluorodeoxyglucose (FDG)-PET and CT scans of the treatment site in the treatment position and then a whole body scan were carried out with a dedicated PET/CT scanner and fused thereafter. FDG-avid primary tumour and lymph nodes were included into the GTV. A multidisciplinary team defined the target volume, and contouring was carried out by a radiation oncologist using visual methods. To compare the PET/CT-based volumes with CT-based volumes, contours were drawn on CT-only data with the help of site-specific radiologists who were blind to the PET/CT results after a median time of 7 months. In general, our PET/CT volumes were larger than our CT-based volumes. This difference was significant in patients with head and neck cancers. Major changes (> or =25%) in GTV delineation were observed in 44% of patients. In 16% of cases, PET/CT detected incidental second primaries and metastatic disease, changing the treatment strategy from curative to palliative. Integrating functional imaging with FDG-PET/CT into the radiotherapy planning process resulted in major changes in a significant proportion of our patients. An interdisciplinary approach between imaging and radiation oncology departments is essential in defining the target volumes. Copyright 2010 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

SU-E-T-237: Deformable Image Registration and Deformed Dose Composite for Volumetric Evaluation of Multimodal Gynecological Cancer Treatments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albani, D; Sherertz, T; Ellis, R

2015-06-15

Purpose: Radiotherapy plans for patients with cervical cancer treated with EBRT followed by HDR brachytherapy are optimized by constraining dose to organs at risk (OARs). Risk of treatment related toxicities is estimated based on the dose received to the hottest 2cc (D2cc) of the bladder, bowel, rectum, and sigmoid. To account for intrafractional variation in OAR volume and positioning, a dose deformation method is proposed for more accurate evaluation of dose distribution for these patients. Methods: Radiotherapy plans from five patients who received 50.4Gy pelvic EBRT followed by 30Gy in five fractions of HDR brachytherapy, using split-ring and tandem applicators,more » were retrospectively evaluated using MIM Software version 6.0. Dose accumulation workflows were used for initial deformation of EBRT and HDR planning CTs onto a common HDR planning CT. The Reg Refine tool was applied with user-specified local alignments to refine the deformation. Doses from the deformed images were transferred to the common planning CT. Deformed doses were scaled to the EQD2, following the linear-quadratic BED model (considered α/β ratio for tumor as 10, and 3 for rest of the tissues), and then combined to create the dose composite. MIM composite doses were compared to the clinically-reported plan assessments based upon the American Brachytherapy Society (ABS) guidelines for cervical HDR brachytherapy treatment. Results: Bladder D2cc exhibited significant reduction (−11.4%±3.85%, p< 0.02) when evaluated using MIM deformable dose composition. Differences observed for bowel, rectum, and sigmoid D2cc were not significant (−0.58±7.37%, −4.13%±13.7%, and 8.58%±4.71%, respectively and p>0.05 for all) relative to the calculated values used clinically. Conclusion: Application of deformable dose composite techniques may lead to more accurate total dose reporting and can allow for elevated dose to target structures with the assurance of not exceeding dose to OARs. Further study into deformable dose composition and correlation with clinical outcomes is warranted.« less

Treatment of pediatric patients and young adults with particle therapy at the Heidelberg Ion Therapy Center (HIT): establishment of workflow and initial clinical data

PubMed Central

2012-01-01

Background To report on establishment of workflow and clinical results of particle therapy at the Heidelberg Ion Therapy Center. Materials and methods We treated 36 pediatric patients (aged 21 or younger) with particle therapy at HIT. Median age was 12 years (range 2-21 years), five patients (14%) were younger than 5 years of age. Indications included pilocytic astrocytoma, parameningeal and orbital rhabdomyosarcoma, skull base and cervical chordoma, osteosarcoma and adenoid-cystic carcinoma (ACC), as well as one patient with an angiofibroma of the nasopharynx. For the treatment of small children, an anesthesia unit at HIT was established in cooperation with the Department of Anesthesiology. Results Treatment concepts depended on tumor type, staging, age of the patient, as well as availability of specific study protocols. In all patients, particle radiotherapy was well tolerated and no interruptions due to toxicity had to be undertaken. During follow-up, only mild toxicites were observed. Only one patient died of tumor progression: Carbon ion radiotherapy was performed as an individual treatment approach in a child with a skull base recurrence of the previously irradiated rhabdomyosarcoma. Besides this patient, tumor recurrence was observed in two additional patients. Conclusion Clinical protocols have been generated to evaluate the real potential of particle therapy, also with respect to carbon ions in distinct pediatric patient populations. The strong cooperation between the pediatric department and the department of radiation oncology enable an interdisciplinary treatment and stream-lined workflow and acceptance of the treatment for the patients and their parents. PMID:23072718

Sci-Thur PM – Colourful Interactions: Highlights 01: Design to delivery of spatially fractionated mini-beam canine radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alexander, Andrew; Crewson, Cody; Davis, William

Spatial fractionation of radiation using arrays of narrow parallel micro-planar beams (less than 1 mm), is a relatively new concept with many unknowns specifically within the underlying biology of cell death. A tungsten collimator has been designed to produce mini-beams with a Varian linear accelerator for translational animal research into the effectiveness of spatial fractionation mini-beam radiotherapy (MBRT). This work presents the treatment planning process and workflow for the application of MBRT treatments within a clinical study. For patient dose calculations, the MBRT collimator was incorporated into a Monte Carlo based treatment planning system called MMCTP. Treatment planning was splitmore » between Eclipse and MMCTP, as the field apertures were determined within Eclipse prior to being sent to MMCTP for dose calculations. The calculated plan was transferred back into Aria with updated MUs per field for patient treatment. Patients were positioned within a vac-lock bag lying prone with a bite block and a thermoplastic mask to immobilize the head. Prior to treatment, a delivery verification plan was created within MMCTP. DQA output measurements of the treatment fields agreed with the calculated dose to within 1.5%. We have presented a workflow for MBRT treatments that include the planning technique, dose calculation method, DQA process and data integration into a record and verify system. The clinical study following this workflow represent the first series of linac based MBRT patients and depending on the clinical outcome of the study, our technique could be applied to human MBRT treatments.« less

Quantitative Body Mass Characterization Before and After Head and Neck Cancer Radiotherapy: A Challenge of Height-Weight Formulae Using Computed Tomography Measurement

PubMed Central

Chamchod, Sasikarn; Fuller, Clifton D.; Mohamed, Abdallah S.R.; Grossberg, Aaron; Messer, Jay A.; Heukelom, Jolien; Gunn, G. Brandon; Kantor, Micheal E.; Eichelberger, Hillary; Garden, Adam S.; Rosenthal, David I.

2016-01-01

Objectives We undertook a challenge to determine if one or more height-weight formula(e) can be clinically used as a surrogate for direct CT-based imaging assessment of body composition before and after radiotherapy for head and neck cancer (HNC) patients, who are at risk for cancer- and therapy-associated cachexia/sarcopenia. Materials and Methods This retrospective single-institution study included 215 HNC patients, treated with curative radiotherapy between 2003 and 2013. Height/weight measures were tabulated. Skeletal muscle mass was contoured on pre- and post-treatment CT at the L3 vertebral level. Three common lean body mass (LBM) formulae (Hume, Boer, and James) were calculated, and compared to CT assessment at each time point. Results 156 patients (73%) had tumors arising in the oropharynx and 130 (61%) received concurrent chemotherapy. Mean pretreatment body mass index (BMI) was 28.5 ± 4.9 kg/m2 in men and 27.8 ± 8 kg/m2 in women. Mean post-treatment BMI were 26.2 ± 4.4 kg/m2 in men, 26 ± 7.5 kg/m2 in women. Mean CT-derived LBM decreased from 55.2±11.8 kg pre-therapy to 49.27±9.84 kg post-radiation. Methods comparison revealed 95% limit of agreement of ±12.5–13.2 kg between CT and height-weight formulae. Post-treatment LBM with the three formulae was significantly different from CT (p<0.0001). In all instances, no height-weight formula was practically equivalent to CT within ±5 kg. Conclusion Formulae cannot accurately substitute for direct quantitative imaging LBM measurements. We therefore recommend CT-based LBM assessment as a routine practice of head and neck cancer patient body composition. PMID:27688106

MO-H-19A-03: Patient Specific Bolus with 3D Printing Technology for Electron Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zou, W; Swann, B; Siderits, R

2014-06-15

Purpose: Bolus is widely used in electron radiotherapy to achieve desired dose distribution. 3D printing technologies provide clinicians with easy access to fabricate patient specific bolus accommodating patient body surface irregularities and tissue inhomogeneity. This study presents the design and the clinical workflow of 3D printed bolus for patient electron therapy in our clinic. Methods: Patient simulation CT images free of bolus were exported from treatment planning system (TPS) to an in-house developed software package. Bolus with known material properties was designed in the software package and then exported back to the TPS as a structure. Dose calculation was carriedmore » out to examine the coverage of the target. After satisfying dose distribution was achieved, the bolus structure was transferred in Standard Tessellation Language (STL) file format for the 3D printer to generate the machine codes for printing. Upon receiving printed bolus, a quick quality assurance was performed with patient resimulated with bolus in place to verify the bolus dosimetric property before treatment started. Results: A patient specific bolus for electron radiotherapy was designed and fabricated in Form 1 3D printer with methacrylate photopolymer resin. Satisfying dose distribution was achieved in patient with bolus setup. Treatment was successfully finished for one patient with the 3D printed bolus. Conclusion: The electron bolus fabrication with 3D printing technology was successfully implemented in clinic practice.« less

SYRMEP Tomo Project: a graphical user interface for customizing CT reconstruction workflows.

PubMed

Brun, Francesco; Massimi, Lorenzo; Fratini, Michela; Dreossi, Diego; Billé, Fulvio; Accardo, Agostino; Pugliese, Roberto; Cedola, Alessia

2017-01-01

When considering the acquisition of experimental synchrotron radiation (SR) X-ray CT data, the reconstruction workflow cannot be limited to the essential computational steps of flat fielding and filtered back projection (FBP). More refined image processing is often required, usually to compensate artifacts and enhance the quality of the reconstructed images. In principle, it would be desirable to optimize the reconstruction workflow at the facility during the experiment (beamtime). However, several practical factors affect the image reconstruction part of the experiment and users are likely to conclude the beamtime with sub-optimal reconstructed images. Through an example of application, this article presents SYRMEP Tomo Project (STP), an open-source software tool conceived to let users design custom CT reconstruction workflows. STP has been designed for post-beamtime (off-line use) and for a new reconstruction of past archived data at user's home institution where simple computing resources are available. Releases of the software can be downloaded at the Elettra Scientific Computing group GitHub repository https://github.com/ElettraSciComp/STP-Gui.

PET/CT image registration: preliminary tests for its application to clinical dosimetry in radiotherapy.

PubMed

Baños-Capilla, M C; García, M A; Bea, J; Pla, C; Larrea, L; López, E

2007-06-01

The quality of dosimetry in radiotherapy treatment requires the accurate delimitation of the gross tumor volume. This can be achieved by complementing the anatomical detail provided by CT images through fusion with other imaging modalities that provide additional metabolic and physiological information. Therefore, use of multiple imaging modalities for radiotherapy treatment planning requires an accurate image registration method. This work describes tests carried out on a Discovery LS positron emission/computed tomography (PET/CT) system by General Electric Medical Systems (GEMS), for its later use to obtain images to delimit the target in radiotherapy treatment. Several phantoms have been used to verify image correlation, in combination with fiducial markers, which were used as a system of external landmarks. We analyzed the geometrical accuracy of two different fusion methods with the images obtained with these phantoms. We first studied the fusion method used by the PET/CT system by GEMS (hardware fusion) on the basis that there is satisfactory coincidence between the reconstruction centers in CT and PET systems; and secondly the fiducial fusion, a registration method, by means of least-squares fitting algorithm of a landmark points system. The study concluded with the verification of the centroid position of some phantom components in both imaging modalities. Centroids were estimated through a calculation similar to center-of-mass, weighted by the value of the CT number and the uptake intensity in PET. The mean deviations found for the hardware fusion method were: deltax/ +/-sigma = 3.3 mm +/- 1.0 mm and /deltax/ +/-sigma = 3.6 mm +/- 1.0 mm. These values were substantially improved upon applying fiducial fusion based on external landmark points: /deltax/ +/-sigma = 0.7 mm +/- 0.8 mm and /deltax/ +/-sigma = 0.3 mm 1.7 mm. We also noted that differences found for each of the fusion methods were similar for both the axial and helical CT image acquisition protocols.

The impact of PET/CT scanning on the size of target volumes, radiation exposure of organs at risk, TCP and NTCP, in the radiotherapy planning of non-small cell lung cancer.

PubMed

Vojtíšek, Radovan; Mužík, Jan; Slampa, Pavel; Budíková, Marie; Hejsek, Jaroslav; Smolák, Petr; Ferda, Jiří; Fínek, Jindřich

2014-05-01

To compare radiotherapy plans made according to CT and PET/CT and to investigate the impact of changes in target volumes on tumour control probability (TCP), normal tissue complication probability (NTCP) and the impact of PET/CT on the staging and treatment strategy. Contemporary studies have proven that PET/CT attains higher sensitivity and specificity in the diagnosis of lung cancer and also leads to higher accuracy than CT alone in the process of target volume delineation in NSCLC. Between October 2009 and March 2012, 31 patients with locally advanced NSCLC, who had been referred to radical radiotherapy were involved in our study. They all underwent planning PET/CT examination. Then we carried out two separate delineations of target volumes and two radiotherapy plans and we compared the following parameters of those plans: staging, treatment purpose, the size of GTV and PTV and the exposure of organs at risk (OAR). TCP and NTCP were also compared. PET/CT information led to a significant decrease in the sizes of target volumes, which had the impact on the radiation exposure of OARs. The reduction of target volume sizes was not reflected in the significant increase of the TCP value. We found that there is a very strong direct linear relationship between all evaluated dosimetric parameters and NTCP values of all evaluated OARs. Our study found that the use of planning PET/CT in the radiotherapy planning of NSCLC has a crucial impact on the precise determination of target volumes, more precise staging of the disease and thus also on possible changes of treatment strategy.

A multimodality segmentation framework for automatic target delineation in head and neck radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Jinzhong; Aristophanous, Michalis, E-mail: MAristophanous@mdanderson.org; Beadle, Beth M.

2015-09-15

Purpose: To develop an automatic segmentation algorithm integrating imaging information from computed tomography (CT), positron emission tomography (PET), and magnetic resonance imaging (MRI) to delineate target volume in head and neck cancer radiotherapy. Methods: Eleven patients with unresectable disease at the tonsil or base of tongue who underwent MRI, CT, and PET/CT within two months before the start of radiotherapy or chemoradiotherapy were recruited for the study. For each patient, PET/CT and T1-weighted contrast MRI scans were first registered to the planning CT using deformable and rigid registration, respectively, to resample the PET and magnetic resonance (MR) images to themore » planning CT space. A binary mask was manually defined to identify the tumor area. The resampled PET and MR images, the planning CT image, and the binary mask were fed into the automatic segmentation algorithm for target delineation. The algorithm was based on a multichannel Gaussian mixture model and solved using an expectation–maximization algorithm with Markov random fields. To evaluate the algorithm, we compared the multichannel autosegmentation with an autosegmentation method using only PET images. The physician-defined gross tumor volume (GTV) was used as the “ground truth” for quantitative evaluation. Results: The median multichannel segmented GTV of the primary tumor was 15.7 cm{sup 3} (range, 6.6–44.3 cm{sup 3}), while the PET segmented GTV was 10.2 cm{sup 3} (range, 2.8–45.1 cm{sup 3}). The median physician-defined GTV was 22.1 cm{sup 3} (range, 4.2–38.4 cm{sup 3}). The median difference between the multichannel segmented and physician-defined GTVs was −10.7%, not showing a statistically significant difference (p-value = 0.43). However, the median difference between the PET segmented and physician-defined GTVs was −19.2%, showing a statistically significant difference (p-value =0.0037). The median Dice similarity coefficient between the multichannel segmented and physician-defined GTVs was 0.75 (range, 0.55–0.84), and the median sensitivity and positive predictive value between them were 0.76 and 0.81, respectively. Conclusions: The authors developed an automated multimodality segmentation algorithm for tumor volume delineation and validated this algorithm for head and neck cancer radiotherapy. The multichannel segmented GTV agreed well with the physician-defined GTV. The authors expect that their algorithm will improve the accuracy and consistency in target definition for radiotherapy.« less

Functional Image-Guided Radiotherapy Planning in Respiratory-Gated Intensity-Modulated Radiotherapy for Lung Cancer Patients With Chronic Obstructive Pulmonary Disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kimura, Tomoki, E-mail: tkkimura@hiroshima-u.ac.jp; Nishibuchi, Ikuno; Murakami, Yuji

2012-03-15

Purpose: To investigate the incorporation of functional lung image-derived low attenuation area (LAA) based on four-dimensional computed tomography (4D-CT) into respiratory-gated intensity-modulated radiotherapy (IMRT) or volumetric modulated arc therapy (VMAT) in treatment planning for lung cancer patients with chronic obstructive pulmonary disease (COPD). Methods and Materials: Eight lung cancer patients with COPD were the subjects of this study. LAA was generated from 4D-CT data sets according to CT values of less than than -860 Hounsfield units (HU) as a threshold. The functional lung image was defined as the area where LAA was excluded from the image of the total lung.more » Two respiratory-gated radiotherapy plans (70 Gy/35 fractions) were designed and compared in each patient as follows: Plan A was an anatomical IMRT or VMAT plan based on the total lung; Plan F was a functional IMRT or VMAT plan based on the functional lung. Dosimetric parameters (percentage of total lung volume irradiated with {>=}20 Gy [V20], and mean dose of total lung [MLD]) of the two plans were compared. Results: V20 was lower in Plan F than in Plan A (mean 1.5%, p = 0.025 in IMRT, mean 1.6%, p = 0.044 in VMAT) achieved by a reduction in MLD (mean 0.23 Gy, p = 0.083 in IMRT, mean 0.5 Gy, p = 0.042 in VMAT). No differences were noted in target volume coverage and organ-at-risk doses. Conclusions: Functional IGRT planning based on LAA in respiratory-guided IMRT or VMAT appears to be effective in preserving a functional lung in lung cancer patients with COPD.« less

SU-E-J-97: Evaluation of Multi-Modality (CT/MR/PET) Image Registration Accuracy in Radiotherapy Planning.

PubMed

Sethi, A; Rusu, I; Surucu, M; Halama, J

2012-06-01

Evaluate accuracy of multi-modality image registration in radiotherapy planning process. A water-filled anthropomorphic head phantom containing eight 'donut-shaped' fiducial markers (3 internal + 5 external) was selected for this study. Seven image sets (3CTs, 3MRs and PET) of phantom were acquired and fused in a commercial treatment planning system. First, a narrow slice (0.75mm) baseline CT scan was acquired (CT1). Subsequently, the phantom was re-scanned with a coarse slice width = 1.5mm (CT2) and after subjecting phantom to rotation/displacement (CT3). Next, the phantom was scanned in a 1.5 Tesla MR scanner and three MR image sets (axial T1, axial T2, coronal T1) were acquired at 2mm slice width. Finally, the phantom and center of fiducials were doped with 18F and a PET scan was performed with 2mm cubic voxels. All image scans (CT/MR/PET) were fused to the baseline (CT1) data using automated mutual-information based fusion algorithm. Difference between centroids of fiducial markers in various image modalities was used to assess image registration accuracy. CT/CT image registration was superior to CT/MR and CT/PET: average CT/CT fusion error was found to be 0.64 ± 0.14 mm. Corresponding values for CT/MR and CT/PET fusion were 1.33 ± 0.71mm and 1.11 ± 0.37mm. Internal markers near the center of phantom fused better than external markers placed on the phantom surface. This was particularly true for the CT/MR and CT/PET. The inferior quality of external marker fusion indicates possible distortion effects toward the edges of MR image. Peripheral targets in the PET scan may be subject to parallax error caused by depth of interaction of photons in detectors. Current widespread use of multimodality imaging in radiotherapy planning calls for periodic quality assurance of image registration process. Such studies may help improve safety and accuracy in treatment planning. © 2012 American Association of Physicists in Medicine.

TU-F-CAMPUS-J-01: Dosimetric Effects of HU Changes During the Course of Proton Therapy for Lung Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Teng, C; Yin, L; Ainsley, C

2015-06-15

Purpose: To characterize the changes in Hounsfield unit (HU) in lung radiotherapy with proton beams during the course of treatment and to study the effect on the proton plan dose distribution. Methods: Twenty consecutive patients with non-small cell lung cancer treated with proton radiotherapy who underwent multiple CT scans including the planning CT and weekly verification CTs were studied. HU histograms were computed for irradiated lung volumes in beam paths for all scans using the same treatment plan. Histograms for un-irradiated lung volume were used as control to characterize inter-scan variations. HU statistics were calculated for both irradiated and un-irradiatedmore » lung volumes for each patient scan. Further, multiple CT scans based on the same planning CT were generated by replacing the HU of the lung based on the verification CT scans HU values. Using the same beam arrangement, we created plans for each of the altered CT scans to study the dosimetric effect using the dose volume histogram. Results: Lung HU decreased for irradiated lung volume during the course of radiotherapy. The magnitude of this change increased with total irradiation dose. On average, HU changed by −53.8 in the irradiated volume. This change resulted in less than 0.5mm of beam overshoot in tissue for every 1cm beam traversed in the irradiated lung. The dose modification is about +3% for the lung, and less than +1% for the primary tumor. Conclusion: HU of the lung decrease throughout the course of radiation therapy. This change results in a beam overshoot (e.g. 3mm for 6cm of lung traversed) and causes a small dose modification in the overall plan. However, this overshoot does not affect the quality of plans since the margins used in planning, based on proton range uncertainty, are greater. HU needs to change by 150 units before re-planning is warranted.« less

SU-C-17A-07: The Development of An MR Accelerator-Enabled Planning-To-Delivery Technique for Stereotactic Palliative Radiotherapy Treatment of Spinal Metastases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoogcarspel, S J; Kontaxis, C; Velden, J M van der

2014-06-01

Purpose: To develop an MR accelerator-enabled online planning-todelivery technique for stereotactic palliative radiotherapy treatment of spinal metastases. The technical challenges include; automated stereotactic treatment planning, online MR-based dose calculation and MR guidance during treatment. Methods: Using the CT data of 20 patients previously treated at our institution, a class solution for automated treatment planning for spinal bone metastases was created. For accurate dose simulation right before treatment, we fused geometrically correct online MR data with pretreatment CT data of the target volume (TV). For target tracking during treatment, a dynamic T2-weighted TSE MR sequence was developed. An in house developedmore » GPU based IMRT optimization and dose calculation algorithm was used for fast treatment planning and simulation. An automatically generated treatment plan developed with this treatment planning system was irradiated on a clinical 6 MV linear accelerator and evaluated using a Delta4 dosimeter. Results: The automated treatment planning method yielded clinically viable plans for all patients. The MR-CT fusion based dose calculation accuracy was within 2% as compared to calculations performed with original CT data. The dynamic T2-weighted TSE MR Sequence was able to provide an update of the anatomical location of the TV every 10 seconds. Dose calculation and optimization of the automatically generated treatment plans using only one GPU took on average 8 minutes. The Delta4 measurement of the irradiated plan agreed with the dose calculation with a 3%/3mm gamma pass rate of 86.4%. Conclusions: The development of an MR accelerator-enabled planning-todelivery technique for stereotactic palliative radiotherapy treatment of spinal metastases was presented. Future work will involve developing an intrafraction motion adaptation strategy, MR-only dose calculation, radiotherapy quality-assurance in a magnetic field, and streamlining the entire treatment process on an MR accelerator.« less

CT image biomarkers to improve patient-specific prediction of radiation-induced xerostomia and sticky saliva.

PubMed

van Dijk, Lisanne V; Brouwer, Charlotte L; van der Schaaf, Arjen; Burgerhof, Johannes G M; Beukinga, Roelof J; Langendijk, Johannes A; Sijtsema, Nanna M; Steenbakkers, Roel J H M

2017-02-01

Current models for the prediction of late patient-rated moderate-to-severe xerostomia (XER 12m ) and sticky saliva (STIC 12m ) after radiotherapy are based on dose-volume parameters and baseline xerostomia (XER base ) or sticky saliva (STIC base ) scores. The purpose is to improve prediction of XER 12m and STIC 12m with patient-specific characteristics, based on CT image biomarkers (IBMs). Planning CT-scans and patient-rated outcome measures were prospectively collected for 249 head and neck cancer patients treated with definitive radiotherapy with or without systemic treatment. The potential IBMs represent geometric, CT intensity and textural characteristics of the parotid and submandibular glands. Lasso regularisation was used to create multivariable logistic regression models, which were internally validated by bootstrapping. The prediction of XER 12m could be improved significantly by adding the IBM "Short Run Emphasis" (SRE), which quantifies heterogeneity of parotid tissue, to a model with mean contra-lateral parotid gland dose and XER base . For STIC 12m , the IBM maximum CT intensity of the submandibular gland was selected in addition to STIC base and mean dose to submandibular glands. Prediction of XER 12m and STIC 12m was improved by including IBMs representing heterogeneity and density of the salivary glands, respectively. These IBMs could guide additional research to the patient-specific response of healthy tissue to radiation dose. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Investigating the generalisation of an atlas-based synthetic-CT algorithm to another centre and MR scanner for prostate MR-only radiotherapy

NASA Astrophysics Data System (ADS)

Wyatt, Jonathan J.; Dowling, Jason A.; Kelly, Charles G.; McKenna, Jill; Johnstone, Emily; Speight, Richard; Henry, Ann; Greer, Peter B.; McCallum, Hazel M.

2017-12-01

There is increasing interest in MR-only radiotherapy planning since it provides superb soft-tissue contrast without the registration uncertainties inherent in a CT-MR registration. However, MR images cannot readily provide the electron density information necessary for radiotherapy dose calculation. An algorithm which generates synthetic CTs for dose calculations from MR images of the prostate using an atlas of 3 T MR images has been previously reported by two of the authors. This paper aimed to evaluate this algorithm using MR data acquired at a different field strength and a different centre to the algorithm atlas. Twenty-one prostate patients received planning 1.5 T MR and CT scans with routine immobilisation devices on a flat-top couch set-up using external lasers. The MR receive coils were supported by a coil bridge. Synthetic CTs were generated from the planning MR images with (sCT1V ) and without (sCT) a one voxel body contour expansion included in the algorithm. This was to test whether this expansion was required for 1.5 T images. Both synthetic CTs were rigidly registered to the planning CT (pCT). A 6 MV volumetric modulated arc therapy plan was created on the pCT and recalculated on the sCT and sCT1V . The synthetic CTs’ dose distributions were compared to the dose distribution calculated on the pCT. The percentage dose difference at isocentre without the body contour expansion (sCT-pCT) was Δ D_sCT=(0.9 +/- 0.8) % and with (sCT1V -pCT) was Δ D_sCT1V=(-0.7 +/- 0.7) % (mean  ±  one standard deviation). The sCT1V result was within one standard deviation of zero and agreed with the result reported previously using 3 T MR data. The sCT dose difference only agreed within two standard deviations. The mean  ±  one standard deviation gamma pass rate was Γ_sCT = 96.1 +/- 2.9 % for the sCT and Γ_sCT1V = 98.8 +/- 0.5 % for the sCT1V (with 2% global dose difference and 2~mm distance to agreement gamma criteria). The one voxel body contour expansion improves the synthetic CT accuracy for MR images acquired at 1.5 T but requires the MR voxel size to be similar to the atlas MR voxel size. This study suggests that the atlas-based algorithm can be generalised to MR data acquired using a different field strength at a different centre.

The cost of radiotherapy in a decade of technology evolution.

PubMed

Van de Werf, Evelyn; Verstraete, Jan; Lievens, Yolande

2012-01-01

To quantify changes in radiotherapy costs occurring in a decade of medical-technological evolution. The activity-based costing (ABC) model of the University Hospitals Leuven (UHL) radiotherapy (RT) department was adapted to current RT standards. It allocated actual resource costs to the treatments based on the departmental work-flow and patient mix in 2009. A benchmark with the former model analyzed the cost increases related to changes in RT infrastructure and practice over 10 years. A considerable increase in total RT costs was observed, resulting from higher capital investments (96%) and personnel cost (103%), the latter dominating the total picture. Treatment delivery remains the most costly activity, boosted by the cost of improved quality assurance (QA), 23% of total product costs, coming along with more advanced RT techniques. Hence, cost increases at the product level are most obvious for complex treatments, such as intensity-modulated radiotherapy (IMRT), representing cost increases ranging between 38% and 88% compared to conformal approaches. The ABC model provides insight into the financial consequences of evolving technology and practice. Such data are a mandatory first step in our strive to prove RT cost-effectiveness and thus support optimal reimbursement and provision of radiotherapy departments. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

MR-OPERA: A Multicenter/Multivendor Validation of Magnetic Resonance Imaging-Only Prostate Treatment Planning Using Synthetic Computed Tomography Images.

PubMed

Persson, Emilia; Gustafsson, Christian; Nordström, Fredrik; Sohlin, Maja; Gunnlaugsson, Adalsteinn; Petruson, Karin; Rintelä, Niina; Hed, Kristoffer; Blomqvist, Lennart; Zackrisson, Björn; Nyholm, Tufve; Olsson, Lars E; Siversson, Carl; Jonsson, Joakim

2017-11-01

To validate the dosimetric accuracy and clinical robustness of a commercially available software for magnetic resonance (MR) to synthetic computed tomography (sCT) conversion, in an MR imaging-only workflow for 170 prostate cancer patients. The 4 participating centers had MriPlanner (Spectronic Medical), an atlas-based sCT generation software, installed as a cloud-based service. A T2-weighted MR sequence, covering the body contour, was added to the clinical protocol. The MR images were sent from the MR scanner workstation to the MriPlanner platform. The sCT was automatically returned to the treatment planning system. Four MR scanners and 2 magnetic field strengths were included in the study. For each patient, a CT-treatment plan was created and approved according to clinical practice. The sCT was rigidly registered to the CT, and the clinical treatment plan was recalculated on the sCT. The dose distributions from the CT plan and the sCT plan were compared according to a set of dose-volume histogram parameters and gamma evaluation. Treatment techniques included volumetric modulated arc therapy, intensity modulated radiation therapy, and conventional treatment using 2 treatment planning systems and different dose calculation algorithms. The overall (multicenter/multivendor) mean dose differences between sCT and CT dose distributions were below 0.3% for all evaluated organs and targets. Gamma evaluation showed a mean pass rate of 99.12% (0.63%, 1 SD) in the complete body volume and 99.97% (0.13%, 1 SD) in the planning target volume using a 2%/2-mm global gamma criteria. Results of the study show that the sCT conversion method can be used clinically, with minimal differences between sCT and CT dose distributions for target and relevant organs at risk. The small differences seen are consistent between centers, indicating that an MR imaging-only workflow using MriPlanner is robust for a variety of field strengths, vendors, and treatment techniques. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

[Accurate 3D free-form registration between fan-beam CT and cone-beam CT].

PubMed

Liang, Yueqiang; Xu, Hongbing; Li, Baosheng; Li, Hongsheng; Yang, Fujun

2012-06-01

Because the X-ray scatters, the CT numbers in cone-beam CT cannot exactly correspond to the electron densities. This, therefore, results in registration error when the intensity-based registration algorithm is used to register planning fan-beam CT and cone-beam CT. In order to reduce the registration error, we have developed an accurate gradient-based registration algorithm. The gradient-based deformable registration problem is described as a minimization of energy functional. Through the calculus of variations and Gauss-Seidel finite difference method, we derived the iterative formula of the deformable registration. The algorithm was implemented by GPU through OpenCL framework, with which the registration time was greatly reduced. Our experimental results showed that the proposed gradient-based registration algorithm could register more accurately the clinical cone-beam CT and fan-beam CT images compared with the intensity-based algorithm. The GPU-accelerated algorithm meets the real-time requirement in the online adaptive radiotherapy.

Imaging workflow and calibration for CT-guided time-domain fluorescence tomography

PubMed Central

Tichauer, Kenneth M.; Holt, Robert W.; El-Ghussein, Fadi; Zhu, Qun; Dehghani, Hamid; Leblond, Frederic; Pogue, Brian W.

2011-01-01

In this study, several key optimization steps are outlined for a non-contact, time-correlated single photon counting small animal optical tomography system, using simultaneous collection of both fluorescence and transmittance data. The system is presented for time-domain image reconstruction in vivo, illustrating the sensitivity from single photon counting and the calibration steps needed to accurately process the data. In particular, laser time- and amplitude-referencing, detector and filter calibrations, and collection of a suitable instrument response function are all presented in the context of time-domain fluorescence tomography and a fully automated workflow is described. Preliminary phantom time-domain reconstructed images demonstrate the fidelity of the workflow for fluorescence tomography based on signal from multiple time gates. PMID:22076264

[Optimization of radiotherapy planning for non-small cell lung cancer (NSCLC) using 18FDG-PET].

PubMed

Schmidt, S; Nestle, U; Walter, K; Licht, N; Ukena, D; Schnabel, K; Kirsch, C M

2002-10-01

In recent years, FDG-PET examinations have become more important for problems in oncology, especially in staging of bronchogenic carcinoma. In the retrospective study presented here, the influence of PET on the planning of radiotherapy for patients with non-small-cell lung cancer (NSCLC) was investigated. The study involved 39 patients with NSCLC who had been examined by PET for staging. They received radiotherapy on the basis of the anterior/posterior portals including the primary tumour and the mediastinum planned according to CT- and bronchoscopic findings. The results of the PET examination were not considered in initial radiotherapy planning. The portals were retrospectively redefined on the basis of FDG uptake considering the size and localization of the primary tumour; and FDG activities outside the mediastinal part of the portals. In 15 out of 39 patients, the CT/PET-planned portals differed from the CT-planned ones. In most causes (n = 12) the CT/PET field was smaller than the CT field. The median geometric field size of the portals was 179 cm2, after redefinition using PET 166 cm2. In 20 patients with disturbed ventilation caused by the tumour (atelectasis, dystelectosis), a correction of the portal was suggested significantly more frequently than in the other patients (p = 0.03). Our results demonstrate the synergism of topographical (CT) and metabolic (FDG-PET) information, which could be helpful in planning radiotherapy of bronchial carcinoma, especially for patients with disturbed ventilation.

Patch-based generation of a pseudo CT from conventional MRI sequences for MRI-only radiotherapy of the brain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andreasen, Daniel, E-mail: dana@dtu.dk; Van Leemput, Koen; Hansen, Rasmus H.

Purpose: In radiotherapy (RT) based on magnetic resonance imaging (MRI) as the only modality, the information on electron density must be derived from the MRI scan by creating a so-called pseudo computed tomography (pCT). This is a nontrivial task, since the voxel-intensities in an MRI scan are not uniquely related to electron density. To solve the task, voxel-based or atlas-based models have typically been used. The voxel-based models require a specialized dual ultrashort echo time MRI sequence for bone visualization and the atlas-based models require deformable registrations of conventional MRI scans. In this study, we investigate the potential of amore » patch-based method for creating a pCT based on conventional T{sub 1}-weighted MRI scans without using deformable registrations. We compare this method against two state-of-the-art methods within the voxel-based and atlas-based categories. Methods: The data consisted of CT and MRI scans of five cranial RT patients. To compare the performance of the different methods, a nested cross validation was done to find optimal model parameters for all the methods. Voxel-wise and geometric evaluations of the pCTs were done. Furthermore, a radiologic evaluation based on water equivalent path lengths was carried out, comparing the upper hemisphere of the head in the pCT and the real CT. Finally, the dosimetric accuracy was tested and compared for a photon treatment plan. Results: The pCTs produced with the patch-based method had the best voxel-wise, geometric, and radiologic agreement with the real CT, closely followed by the atlas-based method. In terms of the dosimetric accuracy, the patch-based method had average deviations of less than 0.5% in measures related to target coverage. Conclusions: We showed that a patch-based method could generate an accurate pCT based on conventional T{sub 1}-weighted MRI sequences and without deformable registrations. In our evaluations, the method performed better than existing voxel-based and atlas-based methods and showed a promising potential for RT of the brain based only on MRI.« less

Involved-node radiotherapy in early-stage Hodgkin's lymphoma. Definition and guidelines of the German Hodgkin Study Group (GHSG).

PubMed

Eich, Hans Theodor; Müller, Rolf-Peter; Engenhart-Cabillic, Rita; Lukas, Peter; Schmidberger, Heinz; Staar, Susanne; Willich, Normann

2008-08-01

Radiotherapy of Hodgkin's Lymphoma has evolved from extended-field to involved-field (IF) radiotherapy reducing toxicity whilst maintaining high cure rates. Recent publications recommend further reduction in the radiation field to involved-node (IN) radiotherapy; however, this concept has never been tested in a randomized trial. The German Hodgkin Study Group aims to compare it with standard IF radiotherapy in their future HD17 trial. ALL patients must be examined by the radiation oncologist before the start of chemotherapy. At that time, patients must have complete staging CT scans. For patients with IN radiotherapy, a radiation planning CT before and after chemotherapy with patients in the treatment position is recommended. Fusion techniques, allowing the overlapping of the pre- and postchemotherapy CT scans, should be used. Usage of PET-CT scans with patients in the treatment position is recommended, whenever possible. The clinical target volume encompasses the initial volume of the Lymph node(s) before chemotherapy and incorporates the initial Location and extent of the disease taking the displacement of the normal tissues into account. The margin of the planning target volume should be 2 cm in axial and 3 cm in craniocaudal direction. If necessary, it can be reduced to 1-1.5 cm. To minimize Lung and cardiac toxicity, the target definition in the mediastinum is different. The concept of IN radiotherapy has been proposed as a means to further improve the therapeutic ratio by reducing the risk of radiation-induced toxicity, including second malignancies. Field sizes wiLL further decrease compared to IF radiotherapy.

The long- and short-term variability of breathing induced tumor motion in lung and liver over the course of a radiotherapy treatment.

PubMed

Dhont, Jennifer; Vandemeulebroucke, Jef; Burghelea, Manuela; Poels, Kenneth; Depuydt, Tom; Van Den Begin, Robbe; Jaudet, Cyril; Collen, Christine; Engels, Benedikt; Reynders, Truus; Boussaer, Marlies; Gevaert, Thierry; De Ridder, Mark; Verellen, Dirk

2018-02-01

To evaluate the short and long-term variability of breathing induced tumor motion. 3D tumor motion of 19 lung and 18 liver lesions captured over the course of an SBRT treatment were evaluated and compared to the motion on 4D-CT. An implanted fiducial could be used for unambiguous motion information. Fast orthogonal fluoroscopy (FF) sequences, included in the treatment workflow, were used to evaluate motion during treatment. Several motion parameters were compared between different FF sequences from the same fraction to evaluate the intrafraction variability. To assess interfraction variability, amplitude and hysteresis were compared between fractions and with the 3D tumor motion registered by 4D-CT. Population based margins, necessary on top of the ITV to capture all motion variability, were calculated based on the motion captured during treatment. Baseline drift in the cranio-caudal (CC) or anterior-poster (AP) direction is significant (ie. >5 mm) for a large group of patients, in contrary to intrafraction amplitude and hysteresis variability. However, a correlation between intrafraction amplitude variability and mean motion amplitude was found (Pearson's correlation coefficient, r = 0.72, p < 10 -4 ). Interfraction variability in amplitude is significant for 46% of all lesions. As such, 4D-CT accurately captures the motion during treatment for some fractions but not for all. Accounting for motion variability during treatment increases the PTV margins in all directions, most significantly in CC from 5 mm to 13.7 mm for lung and 8.0 mm for liver. Both short-term and day-to-day tumor motion variability can be significant, especially for lesions moving with amplitudes above 7 mm. Abandoning passive motion management strategies in favor of more active ones is advised. Copyright © 2017 Elsevier B.V. All rights reserved.

Adaptive radiotherapy for head and neck cancers: Fact or fallacy to improve therapeutic ratio?

PubMed

Li, Y Q; Tan, J S H; Wee, J T S; Chua, M L K

2018-04-23

Modern standards of precision radiotherapy, primarily driven by the technological advances of intensity modulation and image guidance, have led to increased versatility in radiotherapy planning and delivery. The ability to shape doses around critical normal organs, while simultaneously "painting" boost doses to the tumor have translated to substantial therapeutic gains in head and neck cancer patients. Recently, dose adaptation (or adaptive radiotherapy) has been proposed as a novel concept to enhance the therapeutic ratio of head and neck radiotherapy, facilitated in part by the onset of molecular and functional imaging. These contemporary imaging techniques have enabled visualisation of the spatial molecular architecture of the tumor. Daily cone-beam imaging, besides improving treatment accuracy, offers another unique angle to explore radiomics - a novel high throughput feature extraction and selection workflow, for adapting radiotherapy based on real-time tumor changes. Here, we review the existing evidence of molecular and functional imaging in head and neck cancers, as well as the current application of adaptive radiotherapy in the treatment of this tumor type. We propose that adaptive radiotherapy can be further exploited through a systematic application of molecular and functional imaging, including radiomics, at the different phases of planning and treatment. Copyright © 2018 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

Biological PET-guided adaptive radiotherapy for dose escalation in head and neck cancer: a systematic review.

PubMed

Hamming-Vrieze, Olga; Navran, Arash; Al-Mamgani, Abrahim; Vogel, Wouter V

2018-06-04

In recent years, the possibility of adapting radiotherapy to changes in biological tissue parameters has emerged. It is hypothesized that early identification of radio-resistant parts of the tumor during treatment provides the possibility to adjust the radiotherapy plan to improve outcome. The aim of this systematic literature review was to evaluate the current state of the art of biological PET-guided adaptive radiotherapy, focusing on dose escalation to radio-resistant tumor. A structured literature search was done to select clinical trials including patients with head and neck cancer of the oral cavity, oropharynx, hypopharynx or larynx, with a PET performed during treatment used to develop biological adaptive radiotherapy by i) delineation of sub-volumes suitable for adaptive re-planning, ii) in silico adaptive treatment planning or iii) treatment of patients with PET based dose escalated adaptive radiotherapy. Nineteen articles were selected, 12 articles analyzing molecular imaging signal during treatment and 7 articles focused on biological adaptive treatment planning, of which two were clinical trials. Studied biological pathways include metabolism (FDG), hypoxia (MISO, FAZA and HX4) and proliferation (FLT). In the development of biological dose adaptation in radiotherapy for head-neck tumors, many aspects of the procedure remain ambiguous. Patient selection, tracer selection for detection of the radio-resistant sub-volumes, timing of adaptive radiotherapy, workflow and treatment planning aspects are discussed in a clinical context.

Clinical and computed tomography features of adult abdominopelvic desmoplastic small round cell tumor.

PubMed

Shen, Xun-Ze; Zhao, Jian-Guo; Wu, Jian-Jun; Liu, Fang

2014-05-07

To investigate the clinical and computed tomography (CT) features of desmoplastic small round cell tumor (DSRCT), we retrospectively analyzed the clinical presentations, treatment and outcome, as well as CT manifestations of four cases of DSRCT confirmed by surgery and pathology. The CT manifestations of DSRCT were as follows: (1) multiple soft-tissue masses or diffuse peritoneal thickening in the abdomen and pelvis, with the dominant mass usually located in the pelvic cavity; (2) masses without an apparent organ-based primary site; (3) mild to moderate homogeneous or heterogeneous enhancement in solid area on enhanced CT; and (4) secondary manifestations, such as ascites, hepatic metastases, lymphadenopathy, hydronephrosis and hydroureter. The prognosis and overall survival rates were generally poor. Commonly used treatment strategies including aggressive tumor resection, polychemotherapy, and radiotherapy, showed various therapeutic effects. CT of DSRCT shows characteristic features that are helpful in diagnosis. Early discovery and complete resection, coupled with postoperative adjuvant chemotherapy, are important for prognosis of DSRCT. Whole abdominopelvic rather than locoregional radiotherapy is more effective for unresectable DSRCT.

MO-E-BRD-01: Adapt-A-Thon - Texas Hold’em Invitational

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kessler, M; Brock, K; Pouliot, J

2014-06-15

Software tools for image-based adaptive radiotherapy such as deformable image registration, contour propagation and dose mapping have progressed beyond the research setting and are now commercial products available as part of both treatment planning systems and stand-alone applications. These software tools are used together to create clinical workflows to detect, track and evaluate changes in the patient and to accumulate dose. Deviations uncovered in this process are used to guide decisions about replanning/adaptation with the goal of keeping the delivery of prescribed dose “on target” throughout the entire course of radiotherapy. Since the output from one step of the adaptivemore » process is used as an input for another, it is essential to understand and document the uncertainty associated with each of the step and how these uncertainties are propagated. This in turn requires an understanding how the underlying tools work. Unfortunately, important details about the algorithms used to implement these tools are scarce or incomplete, too often for competitive reasons. This is in contrast to the situation involving other basic treatment planning algorithms such as dose calculations, where the medical physics community essentially requires vendors to provide physically important details about their underlying theory and clinical implementation. Vendors should adopt this same level of information sharing when it comes to the tools and techniques for image guided adaptive radiotherapy. The goal of this session is to start this process by inviting vendors and medical physicists to discuss and demonstrate the available tools and describe how they are intended to be used in clinical practice. The format of the session will involve a combination of formal presentations, interactive demonstrations, audience participation and some friendly “Texas style” competition. Learning Objectives: Understand the components of the image-based adaptive radiotherapy process. Understand the how these components are implemented in various commercial systems. Understand the different use cases and workflows currently supported these tools.« less

Residual neck disease management in squamous-cell carcinoma of the head and neck treated with radiotherapy plus cetuximab.

PubMed

Montal, R; Oliva, M; Taberna, M; De Avila, L; Rovira, A; Cos, M; Mañós, M; Navarro, V; Nogués, J; Lozano, A; Rodríguez, L; Vilajosana, E; Vázquez, S; Mesia, R

2016-11-01

Management of residual neck disease (RND) is one of the unsolved points after bio-radiotherapy (BRT) in loco-regional advanced squamous-cell carcinoma of the head and neck (SCCHN). The aims of the study were to characterize the radiological pattern of response by computed tomography (CT) and to assess the role of positron-emission tomography (PET)/CT in this setting for a better decision-making in the indication of neck dissection (ND). We retrospectively reviewed 202 patients consecutively diagnosed with node-positive SCCHN (N1: 24; N2: 152; N3: 26) who had been treated with concomitant radiotherapy and cetuximab with or without previous induction chemotherapy between 2006 and 2013. Radiological evaluation after treatment was assessed by standard criteria using CT and in addition by PET/CT when RND was suspected in cases from 2010. There were 42 (21 %) patients who achieved complete response of the primary tumor persisting RND by CT. From this group, 24 patients were managed without PET/CT, leading to the performance of ND in 22 (92 %). On the other hand, 18 patients underwent PET/CT and ND was performed in only 6 (33 %). The overall survival was not different between both groups (p = 0.32). After histological examination and follow-up, PET/CT obtained a positive predictive value of 56 % and a negative predictive value of 89 %. Radiological response after BRT is similar to that after treatment with chemo-radiotherapy, thereby validating in this scenario the accepted CT criteria to define complete response of the neck. However, when RND is suspected by CT, PET/CT is useful to prevent unnecessary ND.

Image Fusion for Radiosurgery, Neurosurgery and Hypofractionated Radiotherapy.

PubMed

Inoue, Hiroshi K; Nakajima, Atsushi; Sato, Hiro; Noda, Shin-Ei; Saitoh, Jun-Ichi; Suzuki, Yoshiyuki

2015-03-01

Precise target detection is essential for radiosurgery, neurosurgery and hypofractionated radiotherapy because treatment results and complication rates are related to accuracy of the target definition. In skull base tumors and tumors around the optic pathways, exact anatomical evaluation of cranial nerves are important to avoid adverse effects on these structures close to lesions. Three-dimensional analyses of structures obtained with MR heavy T2-images and image fusion with CT thin-sliced sections are desirable to evaluate fine structures during radiosurgery and microsurgery. In vascular lesions, angiography is most important for evaluations of whole structures from feeder to drainer, shunt, blood flow and risk factors of bleeding. However, exact sites and surrounding structures in the brain are not shown on angiography. True image fusions of angiography, MR images and CT on axial planes are ideal for precise target definition. In malignant tumors, especially recurrent head and neck tumors, biologically active areas of recurrent tumors are main targets of radiosurgery. PET scan is useful for quantitative evaluation of recurrences. However, the examination is not always available at the time of radiosurgery. Image fusion of MR diffusion images with CT is always available during radiosurgery and useful for the detection of recurrent lesions. All images are fused and registered on thin sliced CT sections and exactly demarcated targets are planned for treatment. Follow-up images are also able to register on this CT. Exact target changes, including volume, are possible in this fusion system. The purpose of this review is to describe the usefulness of image fusion for 1) skull base, 2) vascular, 3) recurrent target detection, and 4) follow-up analyses in radiosurgery, neurosurgery and hypofractionated radiotherapy.

Image Fusion for Radiosurgery, Neurosurgery and Hypofractionated Radiotherapy

PubMed Central

Nakajima, Atsushi; Sato, Hiro; Noda, Shin-ei; Saitoh, Jun-ichi; Suzuki, Yoshiyuki

2015-01-01

Precise target detection is essential for radiosurgery, neurosurgery and hypofractionated radiotherapy because treatment results and complication rates are related to accuracy of the target definition. In skull base tumors and tumors around the optic pathways, exact anatomical evaluation of cranial nerves are important to avoid adverse effects on these structures close to lesions. Three-dimensional analyses of structures obtained with MR heavy T2-images and image fusion with CT thin-sliced sections are desirable to evaluate fine structures during radiosurgery and microsurgery. In vascular lesions, angiography is most important for evaluations of whole structures from feeder to drainer, shunt, blood flow and risk factors of bleeding. However, exact sites and surrounding structures in the brain are not shown on angiography. True image fusions of angiography, MR images and CT on axial planes are ideal for precise target definition. In malignant tumors, especially recurrent head and neck tumors, biologically active areas of recurrent tumors are main targets of radiosurgery. PET scan is useful for quantitative evaluation of recurrences. However, the examination is not always available at the time of radiosurgery. Image fusion of MR diffusion images with CT is always available during radiosurgery and useful for the detection of recurrent lesions. All images are fused and registered on thin sliced CT sections and exactly demarcated targets are planned for treatment. Follow-up images are also able to register on this CT. Exact target changes, including volume, are possible in this fusion system. The purpose of this review is to describe the usefulness of image fusion for 1) skull base, 2) vascular, 3) recurrent target detection, and 4) follow-up analyses in radiosurgery, neurosurgery and hypofractionated radiotherapy. PMID:26180676

Clinical evaluation of the iterative metal artifact reduction algorithm for CT simulation in radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Axente, Marian; Von Eyben, Rie; Hristov, Dimitre, E-mail: dimitre.hristov@stanford.edu

2015-03-15

Purpose: To clinically evaluate an iterative metal artifact reduction (IMAR) algorithm prototype in the radiation oncology clinic setting by testing for accuracy in CT number retrieval, relative dosimetric changes in regions affected by artifacts, and improvements in anatomical and shape conspicuity of corrected images. Methods: A phantom with known material inserts was scanned in the presence/absence of metal with different configurations of placement and sizes. The relative change in CT numbers from the reference data (CT with no metal) was analyzed. The CT studies were also used for dosimetric tests where dose distributions from both photon and proton beams weremore » calculated. Dose differences and gamma analysis were calculated to quantify the relative changes between doses calculated on the different CT studies. Data from eight patients (all different treatment sites) were also used to quantify the differences between dose distributions before and after correction with IMAR, with no reference standard. A ranking experiment was also conducted to analyze the relative confidence of physicians delineating anatomy in the near vicinity of the metal implants. Results: IMAR corrected images proved to accurately retrieve CT numbers in the phantom study, independent of metal insert configuration, size of the metal, and acquisition energy. For plastic water, the mean difference between corrected images and reference images was −1.3 HU across all scenarios (N = 37) with a 90% confidence interval of [−2.4, −0.2] HU. While deviations were relatively higher in images with more metal content, IMAR was able to effectively correct the CT numbers independent of the quantity of metal. Residual errors in the CT numbers as well as some induced by the correction algorithm were found in the IMAR corrected images. However, the dose distributions calculated on IMAR corrected images were closer to the reference data in phantom studies. Relative spatial difference in the dose distributions in the regions affected by the metal artifacts was also observed in patient data. However, in absence of a reference ground truth (CT set without metal inserts), these differences should not be interpreted as improvement/deterioration of the accuracy of calculated dose. With limited data presented, it was observed that proton dosimetry was affected more than photons as expected. Physicians were significantly more confident contouring anatomy in the regions affected by artifacts. While site specific preferences were detected, all indicated that they would consistently use IMAR corrected images. Conclusions: IMAR correction algorithm could be readily implemented in an existing clinical workflow upon commercial release. While residual errors still exist in IMAR corrected images, these images present with better overall conspicuity of the patient/phantom geometry and offer more accurate CT numbers for improved local dosimetry. The variety of different scenarios included herein attest to the utility of the evaluated IMAR for a wide range of radiotherapy clinical scenarios.« less

Computed tomography synthesis from magnetic resonance images in the pelvis using multiple random forests and auto-context features

NASA Astrophysics Data System (ADS)

Andreasen, Daniel; Edmund, Jens M.; Zografos, Vasileios; Menze, Bjoern H.; Van Leemput, Koen

2016-03-01

In radiotherapy treatment planning that is only based on magnetic resonance imaging (MRI), the electron density information usually obtained from computed tomography (CT) must be derived from the MRI by synthesizing a so-called pseudo CT (pCT). This is a non-trivial task since MRI intensities are neither uniquely nor quantitatively related to electron density. Typical approaches involve either a classification or regression model requiring specialized MRI sequences to solve intensity ambiguities, or an atlas-based model necessitating multiple registrations between atlases and subject scans. In this work, we explore a machine learning approach for creating a pCT of the pelvic region from conventional MRI sequences without using atlases. We use a random forest provided with information about local texture, edges and spatial features derived from the MRI. This helps to solve intensity ambiguities. Furthermore, we use the concept of auto-context by sequentially training a number of classification forests to create and improve context features, which are finally used to train a regression forest for pCT prediction. We evaluate the pCT quality in terms of the voxel-wise error and the radiologic accuracy as measured by water-equivalent path lengths. We compare the performance of our method against two baseline pCT strategies, which either set all MRI voxels in the subject equal to the CT value of water, or in addition transfer the bone volume from the real CT. We show an improved performance compared to both baseline pCTs suggesting that our method may be useful for MRI-only radiotherapy.

SU-E-J-219: A Dixon Based Pseudo-CT Generation Method for MR-Only Radiotherapy Treatment Planning of the Pelvis and Head and Neck

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maspero, M.; Meijer, G.J.; Lagendijk, J.J.W.

2015-06-15

Purpose: To develop an image processing method for MRI-based generation of electron density maps, known as pseudo-CT (pCT), without usage of model- or atlas-based segmentation, and to evaluate the method in the pelvic and head-neck region against CT. Methods: CT and MRI scans were obtained from the pelvic region of four patients in supine position using a flat table top only for CT. Stratified CT maps were generated by classifying each voxel based on HU ranges into one of four classes: air, adipose tissue, soft tissue or bone.A hierarchical region-selective algorithm, based on automatic thresholding and clustering, was used tomore » classify tissues from MR Dixon reconstructed fat, In-Phase (IP) and Opposed-Phase (OP) images. First, a body mask was obtained by thresholding the IP image. Subsequently, an automatic threshold on the Dixon fat image differentiated soft and adipose tissue. K-means clustering on IP and OP images resulted in a mask that, via a connected neighborhood analysis, allowing the user to select the components corresponding to bone structures.The pCT was estimated through assignment of bulk HU to the tissue classes. Bone-only Digital Reconstructed Radiographs (DRR) were generated as well. The pCT images were rigidly registered to the stratified CT to allow a volumetric and voxelwise comparison. Moreover, pCTs were also calculated within the head-neck region in two volunteers using the same pipeline. Results: The volumetric comparison resulted in differences <1% for each tissue class. A voxelwise comparison showed a good classification, ranging from 64% to 98%. The primary misclassified classes were adipose/soft tissue and bone/soft tissue. As the patients have been imaged on different table tops, part of the misclassification error can be explained by misregistration. Conclusion: The proposed approach does not rely on an anatomy model providing the flexibility to successfully generate the pCT in two different body sites. This research is founded by ZonMw IMDI Programme, project name: “RASOR sharp: MRI based radiotherapy planning using a single MRI sequence”, project number: 10-104003010.« less

Multimodality image integration for radiotherapy treatment: an easy approach

NASA Astrophysics Data System (ADS)

Santos, Andres; Pascau, Javier; Desco, Manuel; Santos, Juan A.; Calvo, Felipe A.; Benito, Carlos; Garcia-Barreno, Rafael

2001-05-01

The interest of using combined MR and CT information for radiotherapy planning is well documented. However, many planning workstations do not allow to use MR images, nor import predefined contours. This paper presents a new simple approach for transferring segmentation results from MRI to a CT image that will be used for radiotherapy planning, using the same original CT format. CT and MRI images of the same anatomical area are registered using mutual information (MI) algorithm. Targets and organs at risk are segmented by the physician on the MR image, where their contours are easy to track. A locally developed software running on PC is used for this step, with several facilities for the segmentation process. The result is transferred onto the CT by slightly modifying up and down the original Hounsfield values of some points of the contour. This is enough to visualize the contour on the CT, but does not affect dose calculations. The CT is then stored using the original file format of the radiotherapy planning workstation, where the technician uses the segmented contour to design the correct beam positioning. The described method has been tested in five patients. Simulations and patient results show that the dose distribution is not affected by the small modification of pixels of the CT image, while the segmented structures can be tracked in the radiotherapy planning workstation-using adequate window/level settings. The presence of the physician is not requires at the planning workstation, and he/she can perform the segmentation process using his/her own PC. This new approach makes it possible to take advantage from the anatomical information present on the MRI and to transfer the segmentation to the CT used for planning, even when the planning workstation does not allow to import external contours. The physician can draw the limits of the target and areas at risk off-line, thus separating in time the segmentation and planning tasks and increasing the efficiency.

Development of Prior Image-based, High-Quality, Low-Dose Kilovoltage Cone Beam CT for Use in Adaptive Radiotherapy of Prostate Cancer

DTIC Science & Technology

2012-05-01

employs kilovoltage (KV) cone- beam CT (CBCT) for guiding treatment. High quality CBCT images are important in achieving improved treatment effect...necessary for achieving successful adaptive RT. Kilovoltage cone-beam CT (CBCT) has shown its capability of yielding such images to guide the prostate cancer...study of low-dose intra-operative cone-beam CT for image- guided surgery,” Proc. SPIE, 7961, 79615P, 2011 10. X. Han, E. Pearson, J. Bian, S. Cho, E. Y

SU-F-J-58: Evaluation of RayStation Hybrid Deformable Image Registration for Accurate Contour Propagation in Adaptive Planning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rong, Y; Rao, S; Daly, M

Purpose: Adaptive radiotherapy requires complete new sets of regions of interests (ROIs) delineation on the mid-treatment CT images. This work aims at evaluating the accuracy of the RayStation hybrid deformable image registration (DIR) algorithm for its overall integrity and accuracy in contour propagation for adaptive planning. Methods: The hybrid DIR is based on the combination of intensity-based algorithm and anatomical information provided by contours. Patients who received mid-treatment CT scans were identified for the study, including six lung patients (two mid-treatment CTs) and six head-and-neck (HN) patients (one mid-treatment CT). DIRpropagated ROIs were compared with physician-drawn ROIs for 8 ITVsmore » and 7 critical organs (lungs, heart, esophagus, and etc.) for the lung patients, as well as 14 GTVs and 20 critical organs (mandible, eyes, parotids, and etc.) for the HN patients. Volume difference, center of mass (COM) difference, and Dice index were used for evaluation. Clinical-relevance of each propagated ROI was scored by two physicians, and correlated with the Dice index. Results: For critical organs, good agreement (Dice>0.9) were seen on all 7 for lung patients and 13 out of 20 for HN patients, with the rest requiring minimal edits. For targets, COM differences were within 5 mm on average for all patients. For Lung, 5 out of 8 ITVs required minimal edits (Dice 0.8–0.9), with the rest 2 needed re-drawn due to their small volumes (<10 cc). However, the propagated HN GTVs resulted in relatively low Dice values (0.5–0.8) due to their small volumes (3–40 cc) and high variability, among which 2 required re-drawn due to new nodal target identified on the mid-treatment CT scans. Conclusion: The hybrid DIR algorithm was found to be clinically useful and efficient for lung and HN patients, especially for propagated critical organ ROIs. It has potential to significantly improve the workflow in adaptive planning.« less

18FDG-PET based radiation planning of mediastinal lymph nodes in limited disease small cell lung cancer changes radiotherapy fields: a planning study.

PubMed

van Loon, Judith; Offermann, Claudia; Bosmans, Geert; Wanders, Rinus; Dekker, André; Borger, Jacques; Oellers, Michel; Dingemans, Anne-Marie; van Baardwijk, Angela; Teule, Jaap; Snoep, Gabriel; Hochstenbag, Monique; Houben, Ruud; Lambin, Philippe; De Ruysscher, Dirk

2008-04-01

To investigate the influence of selective irradiation of 18FDG-PET positive mediastinal nodes on radiation fields and normal tissue exposure in limited disease small cell lung cancer (LD-SCLC). Twenty-one patients with LD-SCLC, of whom both CT and PET images were available, were studied. For each patient, two three-dimensional conformal treatment plans were made with selective irradiation of involved lymph nodes, based on CT and on PET, respectively. Changes in treatment plans as well as dosimetric factors associated with lung and esophageal toxicity were analyzed and compared. FDG-PET information changed the treatment field in 5 patients (24%). In 3 patients, this was due to a decrease and in 2 patients to an increase in the number of involved nodal areas. However, there were no significant differences in gross tumor volume (GTV), lung, and esophageal parameters between CT- and PET-based plans. Incorporating FDG-PET information in radiotherapy planning for patients with LD-SCLC changed the treatment plan in 24% of patients compared to CT. Both increases and decreases of the GTV were observed, theoretically leading to the avoidance of geographical miss or a decrease of radiation exposure of normal tissues, respectively. Based on these findings, a phase II trial, evaluating PET-scan based selective nodal irradiation, is ongoing in our department.

Accurate tracking of tumor volume change during radiotherapy by CT-CBCT registration with intensity correction

NASA Astrophysics Data System (ADS)

Park, Seyoun; Robinson, Adam; Quon, Harry; Kiess, Ana P.; Shen, Colette; Wong, John; Plishker, William; Shekhar, Raj; Lee, Junghoon

2016-03-01

In this paper, we propose a CT-CBCT registration method to accurately predict the tumor volume change based on daily cone-beam CTs (CBCTs) during radiotherapy. CBCT is commonly used to reduce patient setup error during radiotherapy, but its poor image quality impedes accurate monitoring of anatomical changes. Although physician's contours drawn on the planning CT can be automatically propagated to daily CBCTs by deformable image registration (DIR), artifacts in CBCT often cause undesirable errors. To improve the accuracy of the registration-based segmentation, we developed a DIR method that iteratively corrects CBCT intensities by local histogram matching. Three popular DIR algorithms (B-spline, demons, and optical flow) with the intensity correction were implemented on a graphics processing unit for efficient computation. We evaluated their performances on six head and neck (HN) cancer cases. For each case, four trained scientists manually contoured the nodal gross tumor volume (GTV) on the planning CT and every other fraction CBCTs to which the propagated GTV contours by DIR were compared. The performance was also compared with commercial image registration software based on conventional mutual information (MI), VelocityAI (Varian Medical Systems Inc.). The volume differences (mean±std in cc) between the average of the manual segmentations and automatic segmentations are 3.70+/-2.30 (B-spline), 1.25+/-1.78 (demons), 0.93+/-1.14 (optical flow), and 4.39+/-3.86 (VelocityAI). The proposed method significantly reduced the estimation error by 9% (B-spline), 38% (demons), and 51% (optical flow) over the results using VelocityAI. Although demonstrated only on HN nodal GTVs, the results imply that the proposed method can produce improved segmentation of other critical structures over conventional methods.

Use of adjuvant chemotherapy (CT) and radiotherapy (RT) in incompletely resected (R1) early stage Non-Small Cell Lung Cancer (NSCLC): a European survey conducted by the European Society for Medical Oncology (ESMO) young oncologists committee.

PubMed

Califano, R; Karamouzis, M V; Banerjee, S; de Azambuja, E; Guarneri, V; Hutka, M; Jordan, K; Kamposioras, K; Martinelli, E; Corral, J; Postel-Vinay, S; Preusser, M; Porcu, L; Torri, V

2014-07-01

Early stage Non-Small Cell Lung Cancer (NSCLC) is potentially curable with surgery. ESMO guidelines recommend cisplatin-based adjuvant chemotherapy (CT) for completely resected stage II-III NSCLC. There is limited evidence for the use of adjuvant CT and/or radiotherapy (RT) in incompletely resected (R1) early stage NSCLC. A European survey of thoracic oncologists was conducted to evaluate use of adjuvant CT and RT for R1-resected NSCLC and to identify factors influencing treatment decisions. Demographics and information on clinical stage, regimens, cycles planned, radiotherapy sites, multidisciplinary management and discussion about inconclusive evidence with the patient were collected. Univariate and multivariate analyses were performed. 768 surveys were collected from 41 European countries. 82.9% of participants were medical oncologists; 49.3% ESMO members; 37.1% based in University Hospitals; 32.6% practicing oncology for over 15 years and 81.4% active in research. 91.4% of participants prescribed adjuvant CT and mostly cisplatin/vinorelbine (81.2%) or cisplatin/gemcitabine (42.9%). 85% discussed limited clinical evidence with the patient. In the univariate analysis, a statistically significant association with CT prescription was found for medical oncology specialty (p<0.001), ESMO membership (p<0.001), activity in clinical research (p=0.002) and increased frequency of ESMO guidelines consultation (p for trend <0.001). 48.3% of participants prescribed adjuvant RT and its prescription were associated with radiation oncology specialty (p<0.001), not being an ESMO member (p<0.001), years practicing specialty (p for trend=0.001), workload of lung cancer patients (p for trend=0.027) and decreased frequency in consulting ESMO guidelines (p<0.001). In the multivariate analysis, medical oncology and radiation oncology were the best discriminator for prescription of adjuvant CT and RT, respectively. This survey demonstrates that adjuvant CT and RT are commonly used in clinical practice for R1-resected NSCLC despite limited evidence. Prospective trials are necessary to clarify optimal management in this setting. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

SU-F-T-249: Application of Human Factors Methods: Usability Testing in the Radiation Oncology Environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warkentin, H; Bubric, K; Giovannetti, H

2016-06-15

Purpose: As a quality improvement measure, we undertook this work to incorporate usability testing into the implementation procedures for new electronic documents and forms used by four affiliated radiation therapy centers. Methods: A human factors specialist provided training in usability testing for a team of medical physicists, radiation therapists, and radiation oncologists from four radiotherapy centers. A usability testing plan was then developed that included controlled scenarios and standardized forms for qualitative and quantitative feedback from participants, including patients. Usability tests were performed by end users using the same hardware and viewing conditions that are found in the clinical environment.more » A pilot test of a form used during radiotherapy CT simulation was performed in a single department; feedback informed adaptive improvements to the electronic form, hardware requirements, resource accessibility and the usability testing plan. Following refinements to the testing plan, usability testing was performed at three affiliated cancer centers with different vault layouts and hardware. Results: Feedback from the testing resulted in the detection of 6 critical errors (omissions and inability to complete task without assistance), 6 non-critical errors (recoverable), and multiple suggestions for improvement. Usability problems with room layout were detected at one center and problems with hardware were detected at one center. Upon amalgamation and summary of the results, three key recommendations were presented to the document’s authors for incorporation into the electronic form. Documented inefficiencies and patient safety concerns related to the room layout and hardware were presented to administration along with a request for funding to purchase upgraded hardware and accessories to allow a more efficient workflow within the simulator vault. Conclusion: By including usability testing as part of the process when introducing any new document or procedure into clinical use, associated risks can be identified and mitigated before patient care and clinical workflow are impacted.« less

Positron Emission Tomography/Computed Tomography Imaging of Residual Skull Base Chordoma Before Radiotherapy Using Fluoromisonidazole and Fluorodeoxyglucose: Potential Consequences for Dose Painting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mammar, Hamid, E-mail: hamid.mammar@unice.fr; CNRS-UMR 6543, Institute of Developmental Biology and Cancer, University of Nice Sophia Antipolis, Nice; Kerrou, Khaldoun

2012-11-01

Purpose: To detect the presence of hypoxic tissue, which is known to increase the radioresistant phenotype, by its uptake of fluoromisonidazole (18F) (FMISO) using hybrid positron emission tomography/computed tomography (PET/CT) imaging, and to compare it with the glucose-avid tumor tissue imaged with fluorodeoxyglucose (18F) (FDG), in residual postsurgical skull base chordoma scheduled for radiotherapy. Patients and Methods: Seven patients with incompletely resected skull base chordomas were planned for high-dose radiotherapy (dose {>=}70 Gy). All 7 patients underwent FDG and FMISO PET/CT. Images were analyzed qualitatively by visual examination and semiquantitatively by computing the ratio of the maximal standardized uptake valuemore » (SUVmax) of the tumor and cerebellum (T/C R), with delineation of lesions on conventional imaging. Results: Of the eight lesion sites imaged with FDG PET/CT, only one was visible, whereas seven of nine lesions were visible on FMISO PET/CT. The median SUVmax in the tumor area was 2.8 g/mL (minimum 2.1; maximum 3.5) for FDG and 0.83 g/mL (minimum 0.3; maximum 1.2) for FMISO. The T/C R values ranged between 0.30 and 0.63 for FDG (median, 0.41) and between 0.75 and 2.20 for FMISO (median,1.59). FMISO T/C R >1 in six lesions suggested the presence of hypoxic tissue. There was no correlation between FMISO and FDG uptake in individual chordomas (r = 0.18, p = 0.7). Conclusion: FMISO PET/CT enables imaging of the hypoxic component in residual chordomas. In the future, it could help to better define boosted volumes for irradiation and to overcome the radioresistance of these lesions. No relationship was founded between hypoxia and glucose metabolism in these tumors after initial surgery.« less

3D ultrasound-based patient positioning for radiotherapy

NASA Astrophysics Data System (ADS)

Wang, Michael H.; Rohling, Robert N.; Archip, Neculai; Clark, Brenda G.

2006-03-01

A new 3D ultrasound-based patient positioning system for target localisation during radiotherapy is described. Our system incorporates the use of tracked 3D ultrasound scans of the target anatomy acquired using a dedicated 3D ultrasound probe during both the simulation and treatment sessions, fully automatic 3D ultrasound-toultrasound registration, and OPTOTRAK IRLEDs for registering simulation CT to ultrasound data. The accuracy of the entire radiotherapy treatment process resulting from the use of our system, from simulation to the delivery of radiation, has been validated on a phantom. The overall positioning error is less than 5mm, which includes errors from estimation of the irradiated region location in the phantom.

Individualized radiotherapy by combining high-end irradiation and magnetic resonance imaging.

PubMed

Combs, Stephanie E; Nüsslin, Fridtjof; Wilkens, Jan J

2016-04-01

Image-guided radiotherapy (IGRT) has been integrated into daily clinical routine and can today be considered the standard especially with high-dose radiotherapy. Currently imaging is based on MV- or kV-CT, which has clear limitations especially in soft-tissue contrast. Thus, combination of magnetic resonance (MR) imaging and high-end radiotherapy opens a new horizon. The intricate technical properties of MR imagers pose a challenge to technology when combined with radiation technology. Several solutions that are almost ready for routine clinical application have been developed. The clinical questions include dose-escalation strategies, monitoring of changes during treatment as well as imaging without additional radiation exposure during treatment.

On the Detectability of Acoustic Waves Induced Following Irradiation by a Radiotherapy Linear Accelerator.

PubMed

Hickling, Susannah; Leger, Pierre; El Naqa, Issam

2016-02-11

Irradiating an object with a megavoltage photon beam generated by a clinical radiotherapy linear accelerator (linac) induces acoustic waves through the photoacoustic effect. The detection and characterization of such acoustic waves has potential applications in radiation therapy dosimetry. The purpose of this work was to gain insight into the properties of such acoustic waves by simulating and experimentally detecting them in a well-defined system consisting of a metal block suspended in a water tank. A novel simulation workflow was developed by combining radiotherapy Monte Carlo and acoustic wave transport simulation techniques. Different set-up parameters such as photon beam energy, metal block depth, metal block width, and metal block material were varied, and the simulated and experimental acoustic waveforms showed the same relative amplitude trends and frequency variations for such setup changes. The simulation platform developed in this work can easily be extended to other irradiation situations, and will be an invaluable tool for developing a radiotherapy dosimetry system based on the detection of the acoustic waves induced following linear accelerator irradiation.

Comparison of SPECT/CT, MRI and CT in diagnosis of skull base bone invasion in nasopharyngeal carcinoma.

PubMed

Zhang, Shu-xu; Han, Peng-hui; Zhang, Guo-qian; Wang, Rui-hao; Ge, Yong-bin; Ren, Zhi-gang; Li, Jian-sheng; Fu, Wen-hai

2014-01-01

Early detection of skull base invasion in nasopharyngeal carcinoma (NPC) is crucial for correct staging, assessing treatment response and contouring the tumor target in radiotherapy planning, as well as improving the patient's prognosis. To compare the diagnostic efficacy of single photon emission computed tomography/computed tomography (SPECT/CT) imaging, magnetic resonance imaging (MRI) and computed tomography (CT) for the detection of skull base invasion in NPC. Sixty untreated patients with histologically proven NPC underwent SPECT/CT imaging, contrast-enhanced MRI and CT. Of the 60 patients, 30 had skull base invasion confirmed by the final results of contrast-enhanced MRI, CT and six-month follow-up imaging (MRI and CT). The diagnostic efficacy of the three imaging modalities in detecting skull base invasion was evaluated. The rates of positive findings of skull base invasion for SPECT/CT, MRI and CT were 53.3%, 48.3% and 33.3%, respectively. The sensitivity, specificity and accuracy were 93.3%, 86.7% and 90.0% for SPECT/CT fusion imaging, 96.7%, 100.0% and 98.3% for contrast-enhanced MRI, and 66.7%, 100.0% and 83.3% for contrast-enhanced CT. MRI showed the best performance for the diagnosis of skull base invasion in nasopharyngeal carcinoma, followed closely by SPECT/CT. SPECT/CT had poorer specificity than that of both MRI and CT, while CT had the lowest sensitivity.

[Role of 18FDG-PET/CT in the management and gross tumor volume definition for radiotherapy of head and neck cancer; single institution experiences based on long-term follow-up].

PubMed

Hideghéty, Katalin; Cserháti, Adrienne; Besenyi, Zsuzsanna; Zag, Levente; Gaál, Szilvia; Együd, Zsófia; Mózes, Petra; Szántó, Erika; Csenki, Melinda; Rusz, Orsolya; Varga, Zoltán; Dobi, Ágnes; Maráz, Anikó; Pávics, László; Lengyel, Zsolt

2015-06-01

The purpose of our work is evaluation of the impact of 18FDG-PET/CT on the complex management of locoregionally advanced (T3-4N1-3) head and neck squamous cell cancer (LAHNSC), and on the target definition for 3D conformal (3DCRT) and intensity-modulated radiotherapy (IMRT). 18FDG-PET/CT were performed on 185 patients with LAHNSC prior to radiotherapy/chemoradiation in the treatment position between 2006 and 2011. Prior to it 91 patients received induction chemotherapy (in 20 cases of these, baseline PET/CT was also available). The independently delineated CT-based gross tumor volume (GTVct) and PET/CT based ones (GTVpet) were compared. Impact of PET/CT on the treatment strategy, on tumor response evaluation to ICT, on GTV definition furthermore on overall and disease-specific survival (OS, DSS) was analysed. PET/CT revealed 10 head and neck, 2 lung cancers for 15 patients with carcinoma of unknown primary (CUP) while 3 remained unknown. Second tumors were detected in 8 (4.4%), distant metastasis in 15 (8.2%) cases. The difference between GTVct and GTVpet was significant (p=0.001). In 16 patients (14%) the GTVpet were larger than GTVct due to multifocal manifestations in the laryngo-pharyngeal regions (4 cases) or lymph node metastases (12 cases). In the majority of the cases (82 pts, 72%) PET/CT-based conturing resulted in remarkable decrease in the volume (15-20%: 4 cases, 20-50%: 46 cases, >50%: 32 cases). On the basis of the initial and post-ICT PET/CT comparison in 15/20 patients more than 50% volume reduction and in 6/20 cases complete response were achieved. After an average of 6.4 years of follow-up the OS (median: 18.3±2.6 months) and DSS (median: 25.0±4.0 months) exhibited close correlation (p=0.0001) to the GTVpet. In cases with GTVpet <10 cm3 prior to RT, DSS did not reach the median, the mean is 82.1±6.1 months, while in cases with GTVpet 10-40 cm3 the median of the DSS was 28.8±4.9 months (HR = 3.57; 95% CI: 1.5-8.3), and in those with GTVpet >40 cm3 the median DSS was 8.4±0.96 months (HR= 11.48; 95% CI: 5.3-24.9). Our results suggest that 18FDG-PET/CT plays an important role for patient with LAHNSC, by modifying the treatment concept and improving the target definition for selective RT modalities. Volumetric PET/CT-based assessment of the tumor response after ICT gives valuable contribution to further therapy planning.

The impact of computed tomography slice thickness on the assessment of stereotactic, 3D conformal and intensity-modulated radiotherapy of brain tumors.

PubMed

Caivano, R; Fiorentino, A; Pedicini, P; Califano, G; Fusco, V

2014-05-01

To evaluate radiotherapy treatment planning accuracy by varying computed tomography (CT) slice thickness and tumor size. CT datasets from patients with primary brain disease and metastatic brain disease were selected. Tumor volumes ranging from about 2.5 to 100 cc and CT scan at different slice thicknesses (1, 2, 4, 6 and 10 mm) were used to perform treatment planning (1-, 2-, 4-, 6- and 10-CT, respectively). For any slice thickness, a conformity index (CI) referring to 100, 98, 95 and 90 % isodoses and tumor size was computed. All the CI and volumes obtained were compared to evaluate the impact of CT slice thickness on treatment plans. The smallest volumes reduce significantly if defined on 1-CT with respect to 4- and 6-CT, while the CT slice thickness does not affect target definition for the largest volumes. The mean CI for all the considered isodoses and CT slice thickness shows no statistical differences when 1-CT is compared to 2-CT. Comparing the mean CI of 1- with 4-CT and 1- with 6-CT, statistical differences appear only for the smallest volumes with respect to 100, 98 and 95 % isodoses-the CI for 90 % isodose being not statistically significant for all the considered PTVs. The accuracy of radiotherapy tumor volume definition depends on CT slice thickness. To achieve a better tumor definition and dose coverage, 1- and 2-CT would be suitable for small targets, while 4- and 6-CT are suitable for the other volumes.

Visibility of an iron-containing fiducial marker in magnetic resonance imaging for high-precision external beam prostate radiotherapy.

PubMed

Tanaka, Osamu; Komeda, Hisao; Hirose, Shigeki; Taniguchi, Takuya; Ono, Kousei; Matsuo, Masayuki

2017-11-29

Visualization of fiducial gold markers is critical for registration on computed tomography (CT) and magnetic resonance imaging (MRI) for imaging-guided radiotherapy. Although larger markers provide better visualization on MRI, they tend to generate artifacts on CT. MRI is strongly influenced by the presence of metals, such as iron, in the body. Here we compared efficacies of a 0.5% iron-containing gold marker (GM) and a traditional non-iron-containing marker. Twenty-seven patients underwent CT/MRI fusion-based intensity-modulated radiotherapy. Markers were placed by urologists under local anesthesia. Gold Anchor (GA; diameter: 0.28 mm; length: 10 mm), an iron-containing marker, was placed on the right side of the prostate using a 22-G needle and VISICOIL (VIS; diameter: 0.35 mm; length: 10 mm), a non-iron-containing marker, was placed on the left side using a 19-G needle. T2*-weighted images MRI sequences were obtained. Two radiation oncologists and a radiation technologist evaluated and assigned scores for visual quality on a five-point scale (1, poor; 5, best visibility). Artifact generation on CT was slightly greater with GA than with VIS. The mean marker visualization scores on MRI of all three observers were significantly superior for GA than for VIS (3.5 vs 3.2, 3.9 vs 3.2, and 4.0 vs 2.9). The actual size of the spherical GA was about 2 mm in diameter, but the signal void on MRI was approximately 5 mm. Although both markers were well visualized and can be recommended clinically, the results suggest that GA has some subtle advantages for quantitative visualization that could prove useful in certain situations of stereotactic body radiotherapy and intensity-modulated radiotherapy. © 2017 John Wiley & Sons Australia, Ltd.

Optimal Co-segmentation of Tumor in PET-CT Images with Context Information

PubMed Central

Song, Qi; Bai, Junjie; Han, Dongfeng; Bhatia, Sudershan; Sun, Wenqing; Rockey, William; Bayouth, John E.; Buatti, John M.

2014-01-01

PET-CT images have been widely used in clinical practice for radiotherapy treatment planning of the radiotherapy. Many existing segmentation approaches only work for a single imaging modality, which suffer from the low spatial resolution in PET or low contrast in CT. In this work we propose a novel method for the co-segmentation of the tumor in both PET and CT images, which makes use of advantages from each modality: the functionality information from PET and the anatomical structure information from CT. The approach formulates the segmentation problem as a minimization problem of a Markov Random Field (MRF) model, which encodes the information from both modalities. The optimization is solved using a graph-cut based method. Two sub-graphs are constructed for the segmentation of the PET and the CT images, respectively. To achieve consistent results in two modalities, an adaptive context cost is enforced by adding context arcs between the two subgraphs. An optimal solution can be obtained by solving a single maximum flow problem, which leads to simultaneous segmentation of the tumor volumes in both modalities. The proposed algorithm was validated in robust delineation of lung tumors on 23 PET-CT datasets and two head-and-neck cancer subjects. Both qualitative and quantitative results show significant improvement compared to the graph cut methods solely using PET or CT. PMID:23693127

FDG-PET/CT imaging for tumor staging and definition of tumor volumes in radiation treatment planning in non-small cell lung cancer.

PubMed

Zheng, Yuanda; Sun, Xiaojiang; Wang, Jian; Zhang, Lingnan; DI, Xiaoyun; Xu, Yaping

2014-04-01

18 F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) has the potential to improve the staging and radiation treatment (RT) planning of various tumor sites. However, from a clinical standpoint, questions remain with regard to what extent PET/CT changes the target volume and whether PET/CT reduces interobserver variability in target volume delineation. The present study analyzed the use of FDG-PET/CT images for staging and evaluated the impact of FDG-PET/CT on the radiotherapy volume delineation compared with CT in patients with non-small cell lung cancer (NSCLC) who were candidates for radiotherapy. Intraobserver variation in delineating tumor volumes was also observed. In total, 23 patients with stage I-III NSCLC were enrolled and treated with fractionated RT-based therapy with or without chemotherapy. FDG-PET/CT scans were acquired within two weeks prior to RT. PET and CT data sets were sent to the treatment planning system, Pinnacle, through compact discs. The CT and PET images were subsequently fused by means of a dedicated RT planning system. Gross tumor volume (GTV) was contoured by four radiation oncologists on CT (GTV-CT) and PET/CT images (GTV-PET/CT). The resulting volumes were analyzed and compared. For the first phase, two radiation oncologists outlined the contours together, achieving a final consensus. Based on PET/CT, changes in tumor-node-metastasis categories occurred in 8/23 cases (35%). Radiation targeting with fused FDG-PET and CT images resulted in alterations in radiation therapy planning in 12/20 patients (60%) in comparison with CT targeting. The most prominent changes in GTV were observed in cases with atelectasis. For the second phase, the variation in delineating tumor volumes was assessed by four observers. The mean ratio of largest to smallest CT-based GTV was 2.31 (range, 1.01-5.96). The addition of the PET results reduced the mean ratio to 1.46 (range, 1.02-2.27). PET/CT fusion images may have a potential impact on tumor staging and treatment planning. Implementing matched PET/CT results reduced observer variation in delineating tumor volumes significantly with respect to CT only.

PET/CT aids the staging of and radiotherapy planning for early-stage extranodal natural killer/T-cell lymphoma, nasal type: A case series

PubMed Central

2011-01-01

Extranodal natural killer/T-cell lymphoma (ENKTL), nasal type, is a rare form of non-Hodgkin lymphoma. Treatment of ENKTL primarily relies on radiation; thus, proper delineation of target volumes is critical. Currently, the ideal modalities for delineation of gross tumor volume for ENKTL are unknown. We describe three consecutive cases of localized ENKTL that presented to the Nova Scotia Cancer Centre in Halifax, Nova Scotia. All patients had a planning CT and MRI as well as a planning FDG-PET/CT in the radiotherapy treatment position, wearing immobilization masks. All patients received radiation alone. In two patients, PET/CT changed not only the stage, but also the target volume requiring treatment. The third patient was unable to tolerate an MRI, but was able to undergo PET/CT, which improved the accuracy of the target volume. PET/CT aided the staging of and radiotherapy planning for our patients and appears to be a promising tool in the treatment of ENKTL. PMID:22208903

Adaptive nonlocal means filtering based on local noise level for CT denoising

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Zhoubo; Trzasko, Joshua D.; Lake, David S.

2014-01-15

Purpose: To develop and evaluate an image-domain noise reduction method based on a modified nonlocal means (NLM) algorithm that is adaptive to local noise level of CT images and to implement this method in a time frame consistent with clinical workflow. Methods: A computationally efficient technique for local noise estimation directly from CT images was developed. A forward projection, based on a 2D fan-beam approximation, was used to generate the projection data, with a noise model incorporating the effects of the bowtie filter and automatic exposure control. The noise propagation from projection data to images was analytically derived. The analyticalmore » noise map was validated using repeated scans of a phantom. A 3D NLM denoising algorithm was modified to adapt its denoising strength locally based on this noise map. The performance of this adaptive NLM filter was evaluated in phantom studies in terms of in-plane and cross-plane high-contrast spatial resolution, noise power spectrum (NPS), subjective low-contrast spatial resolution using the American College of Radiology (ACR) accreditation phantom, and objective low-contrast spatial resolution using a channelized Hotelling model observer (CHO). Graphical processing units (GPU) implementation of this noise map calculation and the adaptive NLM filtering were developed to meet demands of clinical workflow. Adaptive NLM was piloted on lower dose scans in clinical practice. Results: The local noise level estimation matches the noise distribution determined from multiple repetitive scans of a phantom, demonstrated by small variations in the ratio map between the analytical noise map and the one calculated from repeated scans. The phantom studies demonstrated that the adaptive NLM filter can reduce noise substantially without degrading the high-contrast spatial resolution, as illustrated by modulation transfer function and slice sensitivity profile results. The NPS results show that adaptive NLM denoising preserves the shape and peak frequency of the noise power spectrum better than commercial smoothing kernels, and indicate that the spatial resolution at low contrast levels is not significantly degraded. Both the subjective evaluation using the ACR phantom and the objective evaluation on a low-contrast detection task using a CHO model observer demonstrate an improvement on low-contrast performance. The GPU implementation can process and transfer 300 slice images within 5 min. On patient data, the adaptive NLM algorithm provides more effective denoising of CT data throughout a volume than standard NLM, and may allow significant lowering of radiation dose. After a two week pilot study of lower dose CT urography and CT enterography exams, both GI and GU radiology groups elected to proceed with permanent implementation of adaptive NLM in their GI and GU CT practices. Conclusions: This work describes and validates a computationally efficient technique for noise map estimation directly from CT images, and an adaptive NLM filtering based on this noise map, on phantom and patient data. Both the noise map calculation and the adaptive NLM filtering can be performed in times that allow integration with clinical workflow. The adaptive NLM algorithm provides effective denoising of CT data throughout a volume, and may allow significant lowering of radiation dose.« less

Accumulated Dose in Liver Stereotactic Body Radiotherapy: Positioning, Breathing, and Deformation Effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Velec, Michael, E-mail: michael.velec@rmp.uhn.on.ca; Institute of Medical Science, University of Toronto, Toronto, ON; Moseley, Joanne L.

2012-07-15

Purpose: To investigate the accumulated dose deviations to tumors and normal tissues in liver stereotactic body radiotherapy (SBRT) and investigate their geometric causes. Methods and Materials: Thirty previously treated liver cancer patients were retrospectively evaluated. Stereotactic body radiotherapy was planned on the static exhale CT for 27-60 Gy in 6 fractions, and patients were treated in free-breathing with daily cone-beam CT guidance. Biomechanical model-based deformable image registration accumulated dose over both the planning four-dimensional (4D) CT (predicted breathing dose) and also over each fraction's respiratory-correlated cone-beam CT (accumulated treatment dose). The contribution of different geometric errors to changes between themore » accumulated and predicted breathing dose were quantified. Results: Twenty-one patients (70%) had accumulated dose deviations relative to the planned static prescription dose >5%, ranging from -15% to 5% in tumors and -42% to 8% in normal tissues. Sixteen patients (53%) still had deviations relative to the 4D CT-predicted dose, which were similar in magnitude. Thirty-two tissues in these 16 patients had deviations >5% relative to the 4D CT-predicted dose, and residual setup errors (n = 17) were most often the largest cause of the deviations, followed by deformations (n = 8) and breathing variations (n = 7). Conclusion: The majority of patients had accumulated dose deviations >5% relative to the static plan. Significant deviations relative to the predicted breathing dose still occurred in more than half the patients, commonly owing to residual setup errors. Accumulated SBRT dose may be warranted to pursue further dose escalation, adaptive SBRT, and aid in correlation with clinical outcomes.« less

Dose mapping: validation in 4D dosimetry with measurements and application in radiotherapy follow-up evaluation.

PubMed

Zhang, Geoffrey G; Huang, Tzung-Chi; Forster, Ken M; Lin, Kang-Ping; Stevens, Craig; Harris, Eleanor; Guerrero, Thomas

2008-04-01

The purpose of this paper is to validate a dose mapping program using optical flow method (OFM), and to demonstrate application of the program in radiotherapy follow-up evaluation. For the purpose of validation, the deformation matrices between four-dimensional (4D) CT data of different simulated respiration phases of a phantom were calculated using OFM. The matrices were then used to map doses of all phases to a single-phase image, and summed in equal time weighting. The calculated dose should closely represent the dose delivered to the moving phantom if the deformation matrices are accurately calculated. The measured point doses agreed with the OFM calculations better than 2% at isocenters, and dose distributions better than 1mm for the 50% isodose line. To demonstrate proof-of-concept for the use of deformable image registration in dose mapping for treatment evaluation, the treatment-planning CT was registered with the post-treatment CT image from the positron emission tomography (PET)/CT resulting in a deformation matrix. The dose distribution from the treatment plan was then mapped onto the restaging PET/CT using the deformation matrix. Two cases in which patients had thoracic malignancies are presented. Each patient had CT-based treatment planning for radiotherapy and restaging fluorodeoxy glucose (FDG)-PET/CT imaging 4-6 weeks after completion of treatments. Areas of pneumonitis and recurrence were identified radiographically on both PET and CT restaging images. Local dose and standard uptake values for pneumonitis and recurrence were studied as a demonstration of this method. By comparing the deformable mapped dose to measurement, the treatment evaluation method which is introduced in this manuscript proved to be accurate. It thus provides a more accurate analysis than other rigid or linear dose-image registration when used in studying treatment outcome versus dose.

TU-G-BRA-04: Changes in Regional Lung Function Measured by 4D-CT Ventilation Imaging for Thoracic Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakajima, Y; Kadoya, N; Kabus, S

Purpose: To test the hypothesis: 4D-CT ventilation imaging can show the known effects of radiotherapy on lung function: (1) radiation-induced ventilation reductions, and (2) ventilation increases caused by tumor regression. Methods: Repeat 4D-CT scans (pre-, mid- and/or post-treatment) were acquired prospectively for 11 thoracic cancer patients in an IRB-approved clinical trial. A ventilation image for each time point was created using deformable image registration and the Hounsfield unit (HU)-based or Jacobian-based metric. The 11 patients were divided into two subgroups based on tumor volume reduction using a threshold of 5 cm{sup 3}. To quantify radiation-induced ventilation reduction, six patients whomore » showed a small tumor volume reduction (<5 cm{sup 3}) were analyzed for dose-response relationships. To investigate ventilation increase caused by tumor regression, two of the other five patients were analyzed to compare ventilation changes in the lung lobes affected and unaffected by the tumor. The remaining three patients were excluded because there were no unaffected lobes. Results: Dose-dependent reductions of HU-based ventilation were observed in a majority of the patient-specific dose-response curves and in the population-based dose-response curve, whereas no clear relationship was seen for Jacobian-based ventilation. The post-treatment population-based dose-response curve of HU-based ventilation demonstrated the average ventilation reductions of 20.9±7.0% at 35–40 Gy (equivalent dose in 2-Gy fractions, EQD2), and 40.6±22.9% at 75–80 Gy EQD2. Remarkable ventilation increases in the affected lobes were observed for the two patients who showed an average tumor volume reduction of 37.1 cm{sup 3} and re-opening airways. The mid-treatment increase in HU-based ventilation of patient 3 was 100.4% in the affected lobes, which was considerably greater than 7.8% in the unaffected lobes. Conclusion: This study has demonstrated that 4D-CT ventilation imaging shows the known effects of radiotherapy on lung function: radiation-induced ventilation reduction and ventilation increase caused by tumor regression, providing validation for 4D-CT ventilation imaging. This study was supported in part by a National Lung Cancer Partnership Young Investigator Research grant.« less

Deformable image registration based automatic CT-to-CT contour propagation for head and neck adaptive radiotherapy in the routine clinical setting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumarasiri, Akila, E-mail: akumara1@hfhs.org; Siddiqui, Farzan; Liu, Chang

2014-12-15

Purpose: To evaluate the clinical potential of deformable image registration (DIR)-based automatic propagation of physician-drawn contours from a planning CT to midtreatment CT images for head and neck (H and N) adaptive radiotherapy. Methods: Ten H and N patients, each with a planning CT (CT1) and a subsequent CT (CT2) taken approximately 3–4 week into treatment, were considered retrospectively. Clinically relevant organs and targets were manually delineated by a radiation oncologist on both sets of images. Four commercial DIR algorithms, two B-spline-based and two Demons-based, were used to deform CT1 and the relevant contour sets onto corresponding CT2 images. Agreementmore » of the propagated contours with manually drawn contours on CT2 was visually rated by four radiation oncologists in a scale from 1 to 5, the volume overlap was quantified using Dice coefficients, and a distance analysis was done using center of mass (CoM) displacements and Hausdorff distances (HDs). Performance of these four commercial algorithms was validated using a parameter-optimized Elastix DIR algorithm. Results: All algorithms attained Dice coefficients of >0.85 for organs with clear boundaries and those with volumes >9 cm{sup 3}. Organs with volumes <3 cm{sup 3} and/or those with poorly defined boundaries showed Dice coefficients of ∼0.5–0.6. For the propagation of small organs (<3 cm{sup 3}), the B-spline-based algorithms showed higher mean Dice values (Dice = 0.60) than the Demons-based algorithms (Dice = 0.54). For the gross and planning target volumes, the respective mean Dice coefficients were 0.8 and 0.9. There was no statistically significant difference in the Dice coefficients, CoM, or HD among investigated DIR algorithms. The mean radiation oncologist visual scores of the four algorithms ranged from 3.2 to 3.8, which indicated that the quality of transferred contours was “clinically acceptable with minor modification or major modification in a small number of contours.” Conclusions: Use of DIR-based contour propagation in the routine clinical setting is expected to increase the efficiency of H and N replanning, reducing the amount of time needed for manual target and organ delineations.« less

Sci—Thur AM: YIS - 01: Dosimetric Analysis of Respiratory Induced Cardiac Intrafraction Motion in Left-sided Breast Cancer Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

El-Sherif, O; Xhaferllari, I; Patrick, J

2014-08-15

Introduction: Long-term cardiac side effects in left-sided breast cancer patients (BREL) after post-operative radiotherapy has become one of the most debated issues in radiation oncology. Through breathing-adapted radiotherapy the volume of the heart exposed to radiation can be significantly reduced by delivering the radiation only at the end of inspiration phase of the respiratory cycle, this is referred to as inspiration gating (IG). The purpose of this study is to quantify the potential reduction in cardiac exposure during IG compared to conventional BREL radiotherapy and to assess the dosimetric impact of cardiac motion due to natural breathing. Methods: 24 BRELmore » patients treated with tangential parallel opposed photon beams were included in this study. All patients received a standard fast helical planning CT (FH-CT) and a 4D-CT. Treatment plans were created on the FH-CT using a clinical treatment planning system. The original treatment plan was then superimposed onto the end of inspiration CT and all 10 phases of the 4D-CT to quantify the dosimetric impact of respiratory motion and IG through 4D dose accumulation. Results: Through IG the mean dose to the heart, left ventricle, and left anterior descending artery (LAD) can be reduced in comparison to the clinical standard BREL treatment by as much as 8.39%, 10.11%, and 13.71% respectively (p < 0.05). Conclusion: Failure to account for respiratory motion can lead to under or overestimation in the calculated DVH for the heart, and it's sub-structures. IG can reduce cardiac exposure especially to the LAD during BREL radiotherapy.« less

Salvage radiotherapy in prostate cancer patients. Planning, treatment response and prognosis using (11)C-choline PET/CT.

PubMed

García, J R; Cozar, M; Soler, M; Bassa, P; Riera, E; Ferrer, J

2016-01-01

To assess the prognostic value of the therapeutic response by (11)C-choline PET/CT in prostate cancer patients with biochemical recurrence in which (11)C-choline PET/CT indicated radio-guided radiotherapy. The study included 37 patients initially treated with prostatectomy, who were treated due to biochemical recurrence. (11)C-choline PE/CT detected infra-diaphragmatic lymph-node involvement. All were selected for intensity modulated radiation therapy, escalating the dose according to the PET findings. One year after treatment patients underwent PSA and (11)C-choline PET/CT categorizing response (complete/partial/progression). Clinical/biochemical/image monitoring was performed until appearance of second relapse or 36 months in disease-free patients. (11)C-choline PET/CT could detect lymph nodes in all 37 patients. They were 18 (48.6%) of more than a centimetre in size and 19 (51.3%) with no pathological CT morphology: 9 (24.3%) with positive lymph nodes of around one centimetre and 10 (27.0%) only less than a centimetre in size. The response by (11)C-choline PET/CT was categorised one year after radiotherapy: 16 patients (43.2%) complete response; 15 (40.5%) partial response, and 6 (16.2%) progression. The response was concordant between the PSA result and (11)C-choline PET/CT in 32 patients (86.5%), and discordant in five (13.5%). New recurrence was detected in 12 patients (80%) with partial response, and 5 (31.2%) with complete response. The mean time to recurrence was 9 months after partial response, and 18 months after complete response (significant difference, p<.0001). (11)C-choline PET/CT allows the selection of patients with recurrent prostate cancer candidates for radiotherapy and to plan the technique. The evaluation of therapeutic response by (11)C-choline PET/CT has prognostic significance. Copyright © 2015 Elsevier España, S.L.U. and SEMNIM. All rights reserved.

Supine MRI for regional breast radiotherapy: imaging axillary lymph nodes before and after sentinel-node biopsy

NASA Astrophysics Data System (ADS)

van Heijst, Tristan C. F.; Eschbach-Zandbergen, Debora; Hoekstra, Nienke; van Asselen, Bram; Lagendijk, Jan J. W.; Verkooijen, Helena M.; Pijnappel, Ruud M.; de Waard, Stephanie N.; Witkamp, Arjen J.; van Dalen, Thijs; Desirée van den Bongard, H. J. G.; Philippens, Marielle E. P.

2017-08-01

Regional radiotherapy (RT) is increasingly used in breast cancer treatment. Conventionally, computed tomography (CT) is performed for RT planning. Lymph node (LN) target levels are delineated according to anatomical boundaries. Magnetic resonance imaging (MRI) could enable individual LN delineation. The purpose was to evaluate the applicability of MRI for LN detection in supine treatment position, before and after sentinel-node biopsy (SNB). Twenty-three female breast cancer patients (cTis-3N0M0) underwent 1.5 T MRI, before and after SNB, in addition to CT. Endurance for MRI was monitored. Axillary levels were delineated. LNs were identified and delineated on MRI from before and after SNB, and on CT, and compared by Wilcoxon signed-rank tests. LN locations and LN-based volumes were related to axillary delineations and associated volumes. Although postoperative effects were visible, LN numbers on postoperative MRI (median 26 LNs) were highly reproducible compared to preoperative MRI when adding excised sentinel nodes, and higher than on CT (median 11, p  <  0.001). LN-based volumes were considerably smaller than respective axillary levels. Supine MRI of LNs is feasible and reproducible before and after SNB. This may lead to more accurate RT target definition compared to CT, with potentially lower toxicity. With the MRI techniques described here, initiation of novel MRI-guided RT strategies aiming at individual LNs could be possible.

Tracking Organs Composed of One or Multiple Regions Using Geodesic Active Region Models

NASA Astrophysics Data System (ADS)

Martínez, A.; Jiménez, J. J.

In radiotherapy treatment it is very important to find out the target organs on the medical image sequence in order to determine and apply the proper dose. The techniques to achieve this goal can be classified into extrinsic and intrinsic. Intrinsic techniques only use image processing with medical images associated to the radiotherapy treatment, as we deal in this chapter. To accurately perform this organ tracking it is necessary to find out segmentation and tracking models that were able to be applied to several image modalities involved on a radiotherapy session (CT See Modality , MRI , etc.). The movements of the organs are mainly affected by two factors: breathing and involuntary movements associated with the internal organs or patient positioning. Among the several alternatives to track the organs of interest, a model based on geodesic active regions is proposed. This model has been tested over CT images from the pelvic, cardiac, and thoracic area. A new model for the segmentation of organs composed by more than one region is proposed.

Functional Imaging in Radiotherapy in the Netherlands: Availability and Impact on Clinical Practice.

PubMed

Vogel, W V; Lam, M G E H; Pameijer, F A; van der Heide, U A; van de Kamer, J B; Philippens, M E; van Vulpen, M; Verheij, M

2016-12-01

Functional imaging with positron emission tomography/computed tomography (PET/CT) and multiparametric magnetic resonance (mpMR) is increasingly applied for radiotherapy purposes. However, evidence and experience are still limited, and this may lead to clinically relevant differences in accessibility, interpretation and decision making. We investigated the current patterns of care in functional imaging for radiotherapy in the Netherlands in a care evaluation study. The availability of functional imaging in radiotherapy centres in the Netherlands was evaluated; features available in >80% of academic and >80% of non-academic centres were considered standard of care. The impact of functional imaging on clinical decision making was evaluated using case questionnaires on lung, head/neck, breast and prostate cancer, with multiple-choice questions on primary tumour delineation, nodal involvement, distant metastasis and incidental findings. Radiation oncologists were allowed to discuss cases in a multidisciplinary approach. Ordinal answers were evaluated by median and interquartile range (IQR) to identify the extent and variability of clinical impact; additional patterns were evaluated descriptively. Information was collected from 18 radiotherapy centres in the Netherlands (all except two). PET/CT was available for radiotherapy purposes to 94% of centres; 67% in the treatment position and 61% with integrated planning CT. mpMR was available to all centres; 61% in the treatment position. Technologists collaborated between departments to acquire PET/CT or mpMR for radiotherapy in 89%. All sites could carry out image registration for target definition. Functional imaging generally showed a high clinical impact (average median 4.3, scale 1-6) and good observer agreement (average IQR 1.1, scale 0-6). However, several issues resulted in ignoring functional imaging (e.g. positional discrepancies, central necrosis) or poor observer agreement (atelectasis, diagnostic discrepancies, conformation strategies). Access to functional imaging with PET/CT and mpMR for radiotherapy purposes, with collaborating technologists and multimodal delineation, can be considered standard of care in the Netherlands. For several specific clinical situations, the interpretation of images may benefit from further standardisation. Copyright © 2016 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

A voxel-based investigation for MRI-only radiotherapy of the brain using ultra short echo times

NASA Astrophysics Data System (ADS)

Edmund, Jens M.; Kjer, Hans M.; Van Leemput, Koen; Hansen, Rasmus H.; Andersen, Jon AL; Andreasen, Daniel

2014-12-01

Radiotherapy (RT) based on magnetic resonance imaging (MRI) as the only modality, so-called MRI-only RT, would remove the systematic registration error between MR and computed tomography (CT), and provide co-registered MRI for assessment of treatment response and adaptive RT. Electron densities, however, need to be assigned to the MRI images for dose calculation and patient setup based on digitally reconstructed radiographs (DRRs). Here, we investigate the geometric and dosimetric performance for a number of popular voxel-based methods to generate a so-called pseudo CT (pCT). Five patients receiving cranial irradiation, each containing a co-registered MRI and CT scan, were included. An ultra short echo time MRI sequence for bone visualization was used. Six methods were investigated for three popular types of voxel-based approaches; (1) threshold-based segmentation, (2) Bayesian segmentation and (3) statistical regression. Each approach contained two methods. Approach 1 used bulk density assignment of MRI voxels into air, soft tissue and bone based on logical masks and the transverse relaxation time T2 of the bone. Approach 2 used similar bulk density assignments with Bayesian statistics including or excluding additional spatial information. Approach 3 used a statistical regression correlating MRI voxels with their corresponding CT voxels. A similar photon and proton treatment plan was generated for a target positioned between the nasal cavity and the brainstem for all patients. The CT agreement with the pCT of each method was quantified and compared with the other methods geometrically and dosimetrically using both a number of reported metrics and introducing some novel metrics. The best geometrical agreement with CT was obtained with the statistical regression methods which performed significantly better than the threshold and Bayesian segmentation methods (excluding spatial information). All methods agreed significantly better with CT than a reference water MRI comparison. The mean dosimetric deviation for photons and protons compared to the CT was about 2% and highest in the gradient dose region of the brainstem. Both the threshold based method and the statistical regression methods showed the highest dosimetrical agreement. Generation of pCTs using statistical regression seems to be the most promising candidate for MRI-only RT of the brain. Further, the total amount of different tissues needs to be taken into account for dosimetric considerations regardless of their correct geometrical position.

[Clinical experience in image-guided ultra-conformal hypofractionated radiotherapy in case of metastatic diseases at the University of Pécs].

PubMed

László, Zoltán; Boronkai, Árpád; Lõcsei, Zoltán; Kalincsák, Judit; Szappanos, Szabolcs; Farkas, Róbert; Al Farhat, Yousuf; Sebestyén, Zsolt; Sebestyén, Klára; Kovács, Péter; Csapó, László; Mangel, László

2015-06-01

With the development of radiation therapy technology, the utilization of more accurate patient fixation, inclusion of PET/CT image fusion into treatment planning, 3D image-guided radiotherapy, and intensity-modulated dynamic arc irradiation, the application of hypofractionated stereotactic radiotherapy can be extended to specified extracranial target volumes, and so even to the treatment of various metastases. Between October 2012 and August 2014 in our institute we performed extracranial, hypofractionated, image-többguided radiotherapy with RapidArc system for six cases, and 3D conformal multifield technique for one patient with Novalis TX system in case of different few-numbered and slow-growing metastases. For the precise definition of the target volumes we employed PET/CT during the treatment planning procedure. Octreotid scan was applied in one carcinoid tumour patient. Considering the localisation of the metastases and the predictable motion of the organs, we applied 5 to 20 mm safety margin during the contouring procedure. The average treatment volume was 312 cm3. With 2.5-3 Gy fraction doses we delivered 39-45 Gy total dose, and the treatment duration was 2.5 to 3 weeks. The image guidance was carried out via ExacTrac, and kV-Cone Beam CT equipment based on an online protocol, therefore localisation differences were corrected before every single treatment. The patients tolerated the treatments well without major (Gr>2) side effects. Total or near total regression of the metastases was observed at subsequent control examinations in all cases (the median follow-up time was 5 months). According to our first experience, extracranial, imageguided hypofractionated radiotherapy is well-tolerated by patients and can be effectively applied in the treatment of slow-growing and few-numbered metastases.

SU-F-T-100: Development and Implementation of a Treatment Planning Tracking System Into the Radiation Oncology Clinic

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kabat, C; Cline, K; Li, Y

Purpose: With increasing numbers of cancer patients being diagnosed and the complexity of radiotherapy treatments rising it’s paramount that patient plan development continues to stay fluid within the clinic. In order to maintain a high standard of care and clinical efficiency the establishment of a tracking system for patient plan development allows healthcare providers to view real time plan progression and drive clinical workflow. In addition, it provides statistical datasets which can further identify inefficiencies within the clinic. Methods: An application was developed utilizing Microsoft’s ODBC SQL database engine to track patient plan status throughout the treatment planning process whilemore » also managing key factors pertaining to the patient’s treatment. Pertinent information is accessible to staff in many locations, including tracking monitors within dosimetry, the clinic network for both computers and handheld devices, and through email notifications. Plans are initiated with a CT and continually tracked through planning stages until final approval by staff. Patient’s status is dynamically updated by the physicians, dosimetrists, and medical physicists based on the stage of the patient’s plan. Results: Our application has been running over a six month period with all patients being processed through the system. Modifications have been made to allow for new features to be implemented along with additional tracking parameters. Based on in-house feedback, the application has been supportive in streamlining patient plans through the treatment planning process and data has been accumulating to further improve procedures within the clinic. Conclusion: Over time the clinic will continue to track data with this application. As data accumulates the clinic will be able to highlight inefficiencies within the workflow and adapt accordingly. We will add in new features to help support the treatment planning process in the future.« less

Effect of androgen deprivation therapy on intraprostatic tumour volume identified on 18F choline PET/CT for prostate dose painting radiotherapy.

PubMed

Chan, Joachim; Carver, Antony; Brunt, John N H; Vinjamuri, Sobhan; Syndikus, Isabel

2017-03-01

Prostate dose painting radiotherapy requires the accurate identification of dominant intraprostatic lesions (DILs) to be used as boost volumes; these can be identified on multiparametric MRI (mpMRI) or choline positron emission tomography (PET)/CT. Planning scans are usually performed after 2-3 months of androgen deprivation therapy (ADT). We examine the effect of ADT on choline tracer uptake and boost volumes identified on choline PET/CT. Fluoroethylcholine ( 18 F choline) PET/CT was performed for dose painting radiotherapy planning in patients with intermediate- to high-risk prostate cancer. Initially, they were performed at planning. Owing to low visual tracer uptake, PET/CT for subsequent patients was performed at staging. We compared these two approaches on intraprostatic lesions obtained on PET using both visual and automatic threshold methods [prostate maximum standardized uptake value (SUV max ) 60%] when compared with mpMRI. PET/CT was performed during ADT in 11 patients (median duration of 85 days) and before ADT in 29 patients. ADT significantly reduced overall prostate volume by 17%. During ADT, prostate SUV max was lower although it did not reach statistical significance (4.2 vs 6.6, p = 0.06); three patients had no visually identifiable PET DIL; and visually defined PET DILs were significantly smaller than corresponding mpMRI DILs (p = 0.03). However, all patients scanned before ADT had at least one visually identifiable PET DIL, with no significant size difference between MRI and visually defined PET DILs. In both groups, threshold PET produced larger DILs than visual PET. Both PET methods have moderate sensitivity (0.50-0.68) and high specificity (0.85-0.98) for identifying MRI-defined disease. For visual contouring of boost volumes in prostate dose painting radiotherapy, 18 F choline PET/CT should be performed before ADT. For threshold contouring of boost volumes using our PET/CT scanning protocol, threshold levels of above 60% prostate SUV max may be more suitable. Additional use of PET with MRI for radiotherapy planning can significantly change the overall boost volumes compared with using MRI alone. Advances in knowledge: For prostate dose painting radiotherapy, the additional use of 18 F choline PET with MRI can significantly change the overall boost volumes, and PET should be performed before hormone therapy, especially if boost volumes are visually identified.

[Application of elastic registration based on Demons algorithm in cone beam CT].

PubMed

Pang, Haowen; Sun, Xiaoyang

2014-02-01

We applied Demons and accelerated Demons elastic registration algorithm in radiotherapy cone beam CT (CBCT) images, We provided software support for real-time understanding of organ changes during radiotherapy. We wrote a 3D CBCT image elastic registration program using Matlab software, and we tested and verified the images of two patients with cervical cancer 3D CBCT images for elastic registration, based on the classic Demons algorithm, minimum mean square error (MSE) decreased 59.7%, correlation coefficient (CC) increased 11.0%. While for the accelerated Demons algorithm, MSE decreased 40.1%, CC increased 7.2%. The experimental verification with two methods of Demons algorithm obtained the desired results, but the small difference appeared to be lack of precision, and the total registration time was a little long. All these problems need to be further improved for accuracy and reducing of time.

Respiratory motion-resolved, self-gated 4D-MRI using Rotating Cartesian K-space (ROCK): Initial clinical experience on an MRI-guided radiotherapy system.

PubMed

Han, Fei; Zhou, Ziwu; Du, Dongsu; Gao, Yu; Rashid, Shams; Cao, Minsong; Shaverdian, Narek; Hegde, John V; Steinberg, Michael; Lee, Percy; Raldow, Ann; Low, Daniel A; Sheng, Ke; Yang, Yingli; Hu, Peng

2018-06-01

To optimize and evaluate the respiratory motion-resolved, self-gated 4D-MRI using Rotating Cartesian K-space (ROCK-4D-MRI) method in a 0.35 T MRI-guided radiotherapy (MRgRT) system. The study included seven patients with abdominal tumors treated on the MRgRT system. ROCK-4D-MRI and 2D-CINE, was performed immediately after one of the treatment fractions. Motion quantification based on 4D-MRI was compared with those based on 2D-CINE. The image quality of 4D-MRI was evaluated against 4D-CT. The gross tumor volumes (GTV) were defined based on individual respiratory phases of both 4D-MRI and 4D-CT and compared for their variability over the respiratory cycle. The motion measurements based on 4D-MRI matched well with 2D-CINE, with differences of 1.04 ± 0.52 mm in the superior-inferior and 0.54 ± 0.21 mm in the anterior-posterior directions. The image quality scores of 4D-MRI were significantly higher than 4D-CT, with better tumor contrast (3.29 ± 0.76 vs. 1.86 ± 0.90) and less motion artifacts (3.57 ± 0.53 vs. 2.29 ± 0.95). The GTVs were more consistent in 4D-MRI than in 4D-CT, with significantly smaller GTV variability (9.31 ± 4.58% vs. 34.27 ± 23.33%). Our study demonstrated the clinical feasibility of using the ROCK-4D-MRI to acquire high quality, respiratory motion-resolved 4D-MRI in a low-field MRgRT system. The 4D-MRI image could provide accurate dynamic information for radiotherapy treatment planning. Copyright © 2018 Elsevier B.V. All rights reserved.

SU-F-J-172: Hybrid MR/CT Compatible Phantom for MR-Only Based Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, M; Lee, S; Song, K

2016-06-15

Purpose: Development of hybrid MR/CT compatible phantom was introduced to fully establish MR image only radiation treatment and this suggested technique using in-house developed hybrid MR/CT compatible phantom image would utilize to generate radiation treatment planning and perform dose calculation without multi-modal registration process or generation of pseudo CT. Methods: Fundamental characteristics for “hybrid MR/CT compatible phantom” was established: Relaxation times equivalent to human tissue, dielectric properties, homogeneous relaxation times, sufficient strength to fabricate a torso, ease of handling, a wide variety of density material for calibration, chemical and physical stability over an extended time. For this requirements, chemical componentmore » in each tested plug which would be tissue equivalent to human tissue on MR and CT image and production of phantom body and plug was performed. Chemical component has described below: Agaros, GdCl{sub 3}, NaN{sub 3}, NaCl, K{sub 2}Co{sub 3}, deionized-distilled water. Various mixture of chemical component to simulate human tissue on both MR and CT image was tested by measuring T1, T2 relaxation time and signal intensity (SI) on MR image and Hounsfield unit (HU) on CT and each value was compared. The hybrid MR/CT compatible phantom with 14 plugs was designed and has made. Total height and external diameter was decided by internal size of 32 channel MR head-coil. Results: Tissue-equivalent chemical component materials and hybrid MR/CT compatible phantom was developed. The range of T1, T2 relaxation time and SI on MR image, HU on CT was acquired and could be adjusted to correspond to simulated human tissue. Conclusion: Current result shows its possibility for MR-only based radiotherapy and the best mixing rate of chemical component for tissue-equivalent image on MR and CT was founded. However, additional technical issues remain to be overcome. Conversion of SI on MR image into HU and dose calculation based on converted MRI will be progressing.« less

Comparison of manual and automatic MR-CT registration for radiotherapy of prostate cancer.

PubMed

Korsager, Anne Sofie; Carl, Jesper; Riis Østergaard, Lasse

2016-05-08

In image-guided radiotherapy (IGRT) of prostate cancer, delineation of the clini-cal target volume (CTV) often relies on magnetic resonance (MR) because of its good soft-tissue visualization. Registration of MR and computed tomography (CT) is required in order to add this accurate delineation to the dose planning CT. An automatic approach for local MR-CT registration of the prostate has previously been developed using a voxel property-based registration as an alternative to a manual landmark-based registration. The aim of this study is to compare the two registration approaches and to investigate the clinical potential for replacing the manual registration with the automatic registration. Registrations and analysis were performed for 30 prostate cancer patients treated with IGRT using a Ni-Ti prostate stent as a fiducial marker. The comparison included computing translational and rotational differences between the approaches, visual inspection, and computing the overlap of the CTV. The computed mean translational difference was 1.65, 1.60, and 1.80mm and the computed mean rotational difference was 1.51°, 3.93°, and 2.09° in the superior/inferior, anterior/posterior, and medial/lateral direction, respectively. The sensitivity of overlap was 87%. The results demonstrate that the automatic registration approach performs registrations comparable to the manual registration.

Increased therapeutic ratio by 18FDG-PET CT planning in patients with clinical CT stage N2-N3M0 non-small-cell lung cancer: a modeling study.

PubMed

van Der Wel, Antoinet; Nijsten, Sebastiaan; Hochstenbag, Monique; Lamers, Rob; Boersma, Liesbeth; Wanders, Rinus; Lutgens, Ludy; Zimny, Michael; Bentzen, Søren M; Wouters, Brad; Lambin, Philippe; De Ruysscher, Dirk

2005-03-01

With this modeling study, we wanted to estimate the potential gain from incorporating fluorodeoxyglucose-positron emission tomography (FDG-PET) scanning in the radiotherapy treatment planning of CT Stage N2-N3M0 non-small-cell lung cancer (NSCLC) patients. Twenty-one consecutive patients with clinical CT Stage N2-N3M0 NSCLC were studied. For each patient, two three-dimensional conformal treatment plans were made: one with a CT-based planning target volume (PTV) and one with a PET-CT-based PTV, both to deliver 60 Gy in 30 fractions. From the dose-volume histograms and dose distributions on each plan, the dosimetric factors predicting esophageal and lung toxicity were analyzed and compared. For each patient, the maximal tolerable prescribed radiation dose for the CT PTV vs. PET-CT PTV was calculated according to the constraints for the lung, esophagus, and spinal cord. From these results, the tumor control probability (TCP) was estimated, assuming a clinical dose-response curve with a median toxic dose of 84.5 Gy and a gamma(50) of 2.0. Dose-response curves were modeled, taking into account geographic misses according to the accuracy of CT and PET in our institutions. The gross tumor volume of the nodes decreased from 13.7 +/- 3.8 cm(3) on the CT scan to 9.9 +/- 4.0 cm(3) on the PET-CT scan (p = 0.011). All dose-volume characteristics for the esophagus and lungs decreased in favor of PET-CT. The esophageal V(45) (the volume of the esophagus receiving 45 Gy) decreased from 45.2% +/- 4.9% to 34.0% +/- 5.8% (p = 0.003), esophageal V(55) (the volume of the esophagus receiving 55 Gy) from 30.6% +/- 3.2% to 21.9% +/- 3.8% (p = 0.004), mean esophageal dose from 29.8 +/- 2.5 Gy to 23.7 +/- 3.1 Gy (p = 0.004), lung V(20) (the volume of the lungs minus the PTV receiving 20 Gy) from 24.9% +/- 2.3% to 22.3% +/- 2.2% (p = 0.012), and mean lung dose from 14.7 +/- 1.3 Gy to 13.6 +/- 1.3 Gy (p = 0.004). For the same toxicity levels of the lung, esophagus, and spinal cord, the dose could be increased from 56.0 +/- 5.4 Gy with CT planning to 71.0 +/- 13.7 Gy with PET planning (p = 0.038). The TCP corresponding to these doses was estimated to be 14.2% +/- 5.6% for CT and 22.8% +/- 7.1% for PET-CT planning (p = 0.026). Adjusting for geographic misses by PET-CT vs. CT planning yielded TCP estimates of 12.5% and 18.3% (p = 0.009) for CT and PET-CT planning, respectively. In this group of clinical CT Stage N2-N3 NSCLC patients, use of FDG-PET scanning information in radiotherapy planning reduced the radiation exposure of the esophagus and lung, and thus allowed significant radiation dose escalation while respecting all relevant normal tissue constraints. This, together with a reduced risk of geographic misses using PET-CT, led to an estimated increase in TCP from 13% to 18%. The results of this modeling study support clinical trials investigating incorporation of FDG-PET information in CT-based radiotherapy planning.

System Integration and In Vivo Testing of a Robot for Ultrasound Guidance and Monitoring During Radiotherapy.

PubMed

Sen, Hasan Tutkun; Bell, Muyinatu A Lediju; Zhang, Yin; Ding, Kai; Boctor, Emad; Wong, John; Iordachita, Iulian; Kazanzides, Peter

2017-07-01

We are developing a cooperatively controlled robot system for image-guided radiation therapy (IGRT) in which a clinician and robot share control of a 3-D ultrasound (US) probe. IGRT involves two main steps: 1) planning/simulation and 2) treatment delivery. The goals of the system are to provide guidance for patient setup and real-time target monitoring during fractionated radiotherapy of soft tissue targets, especially in the upper abdomen. To compensate for soft tissue deformations created by the probe, we present a novel workflow where the robot holds the US probe on the patient during acquisition of the planning computerized tomography image, thereby ensuring that planning is performed on the deformed tissue. The robot system introduces constraints (virtual fixtures) to help to produce consistent soft tissue deformation between simulation and treatment days, based on the robot position, contact force, and reference US image recorded during simulation. This paper presents the system integration and the proposed clinical workflow, validated by an in vivo canine study. The results show that the virtual fixtures enable the clinician to deviate from the recorded position to better reproduce the reference US image, which correlates with more consistent soft tissue deformation and the possibility for more accurate patient setup and radiation delivery.

SU-E-T-56: A Novel Approach to Computing Expected Value and Variance of Point Dose From Non-Gated Radiotherapy Delivery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, S; Zhu, X; Zhang, M

Purpose: Randomness in patient internal organ motion phase at the beginning of non-gated radiotherapy delivery may introduce uncertainty to dose received by the patient. Concerns of this dose deviation from the planned one has motivated many researchers to study this phenomenon although unified theoretical framework for computing it is still missing. This study was conducted to develop such framework for analyzing the effect. Methods: Two reasonable assumptions were made: a) patient internal organ motion is stationary and periodic; b) no special arrangement is made to start a non -gated radiotherapy delivery at any specific phase of patient internal organ motion.more » A statistical ensemble was formed consisting of patient’s non-gated radiotherapy deliveries at all equally possible initial organ motion phases. To characterize the patient received dose, statistical ensemble average method is employed to derive formulae for two variables: expected value and variance of dose received by a patient internal point from a non-gated radiotherapy delivery. Fourier Series was utilized to facilitate our analysis. Results: According to our formulae, the two variables can be computed from non-gated radiotherapy generated dose rate time sequences at the point’s corresponding locations on fixed phase 3D CT images sampled evenly in time over one patient internal organ motion period. The expected value of point dose is simply the average of the doses to the point’s corresponding locations on the fixed phase CT images. The variance can be determined by time integration in terms of Fourier Series coefficients of the dose rate time sequences on the same fixed phase 3D CT images. Conclusion: Given a non-gated radiotherapy delivery plan and patient’s 4D CT study, our novel approach can predict the expected value and variance of patient radiation dose. We expect it to play a significant role in determining both quality and robustness of patient non-gated radiotherapy plan.« less

Concurrent segmentation of the prostate on MRI and CT via linked statistical shape models for radiotherapy planning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chowdhury, Najeeb; Toth, Robert; Chappelow, Jonathan

2012-04-15

Purpose: Prostate gland segmentation is a critical step in prostate radiotherapy planning, where dose plans are typically formulated on CT. Pretreatment MRI is now beginning to be acquired at several medical centers. Delineation of the prostate on MRI is acknowledged as being significantly simpler to perform, compared to delineation on CT. In this work, the authors present a novel framework for building a linked statistical shape model (LSSM), a statistical shape model (SSM) that links the shape variation of a structure of interest (SOI) across multiple imaging modalities. This framework is particularly relevant in scenarios where accurate boundary delineations ofmore » the SOI on one of the modalities may not be readily available, or difficult to obtain, for training a SSM. In this work the authors apply the LSSM in the context of multimodal prostate segmentation for radiotherapy planning, where the prostate is concurrently segmented on MRI and CT. Methods: The framework comprises a number of logically connected steps. The first step utilizes multimodal registration of MRI and CT to map 2D boundary delineations of the prostate from MRI onto corresponding CT images, for a set of training studies. Hence, the scheme obviates the need for expert delineations of the gland on CT for explicitly constructing a SSM for prostate segmentation on CT. The delineations of the prostate gland on MRI and CT allows for 3D reconstruction of the prostate shape which facilitates the building of the LSSM. In order to perform concurrent prostate MRI and CT segmentation using the LSSM, the authors employ a region-based level set approach where the authors deform the evolving prostate boundary to simultaneously fit to MRI and CT images in which voxels are classified to be either part of the prostate or outside the prostate. The classification is facilitated by using a combination of MRI-CT probabilistic spatial atlases and a random forest classifier, driven by gradient and Haar features. Results: The authors acquire a total of 20 MRI-CT patient studies and use the leave-one-out strategy to train and evaluate four different LSSMs. First, a fusion-based LSSM (fLSSM) is built using expert ground truth delineations of the prostate on MRI alone, where the ground truth for the gland on CT is obtained via coregistration of the corresponding MRI and CT slices. The authors compare the fLSSM against another LSSM (xLSSM), where expert delineations of the gland on both MRI and CT are employed in the model building; xLSSM representing the idealized LSSM. The authors also compare the fLSSM against an exclusive CT-based SSM (ctSSM), built from expert delineations of the gland on CT alone. In addition, two LSSMs trained using trainee delineations (tLSSM) on CT are compared with the fLSSM. The results indicate that the xLSSM, tLSSMs, and the fLSSM perform equivalently, all of them out-performing the ctSSM. Conclusions: The fLSSM provides an accurate alternative to SSMs that require careful expert delineations of the SOI that may be difficult or laborious to obtain. Additionally, the fLSSM has the added benefit of providing concurrent segmentations of the SOI on multiple imaging modalities.« less

Individualized Margins in 3D Conformal Radiotherapy Planning for Lung Cancer: Analysis of Physiological Movements and Their Dosimetric Impacts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Germain, Francois; Beaulieu, Luc; Fortin, Andre

2008-04-01

In conformal radiotherapy planning for lung cancer, respiratory movements are not taken into account when a single computed tomography (CT) scan is performed. This study examines tumor movements to design individualized margins to account for these movements and evaluates their dosimetric impacts on planning volume. Fifteen patients undergoing CT-based planning for radical radiotherapy for localized lung cancer formed the study cohort. A reference plan was constructed based on reference gross, clinical, and planning target volumes (rGTV, rCTV, and rPTV, respectively). The reference plans were compared with individualized plans using individualized margins obtained by using 5 serial CT scans to generatemore » individualized target volumes (iGTV, iCTV, and iPTV). Three-dimensional conformal radiation therapy was used for plan generation using 6- and 23-MV photon beams. Ten plans for each patient were generated and dose-volume histograms (DVHs) were calculated. Comparisons of volumetric and dosimetric parameters were performed using paired Student t-tests. Relative to the rGTV, the total volume occupied by the superimposed GTVs increased progressively with each additional CT scans. With the use of all 5 scans, the average increase in GTV was 52.1%. For the plans with closest dosimetric coverage, target volume was smaller (iPTV/rPTV ratio 0.808) but lung irradiation was only slightly decreased. Reduction in the proportion of lung tissue that received 20 Gy or more outside the PTV (V20) was observed both for 6-MV plans (-0.73%) and 23-MV plans (-0.65%), with p = 0.02 and p = 0.04, respectively. In conformal RT planning for the treatment of lung cancer, the use of serial CT scans to evaluate respiratory motion and to generate individualized margins to account for these motions produced only a limited lung sparing advantage.« less

MR-CT registration using a Ni-Ti prostate stent in image-guided radiotherapy of prostate cancer.

PubMed

Korsager, Anne Sofie; Carl, Jesper; Østergaard, Lasse Riis

2013-06-01

In image-guided radiotherapy of prostate cancer defining the clinical target volume often relies on magnetic resonance (MR). The task of transferring the clinical target volume from MR to standard planning computed tomography (CT) is not trivial due to prostate mobility. In this paper, an automatic local registration approach is proposed based on a newly developed removable Ni-Ti prostate stent. The registration uses the voxel similarity measure mutual information in a two-step approach where the pelvic bones are used to establish an initial registration for the local registration. In a phantom study, the accuracy was measured to 0.97 mm and visual inspection showed accurate registration of all 30 data sets. The consistency of the registration was examined where translation and rotation displacements yield a rotation error of 0.41° ± 0.45° and a translation error of 1.67 ± 2.24 mm. This study demonstrated the feasibility for an automatic local MR-CT registration using the prostate stent.

MO-C-17A-03: A GPU-Based Method for Validating Deformable Image Registration in Head and Neck Radiotherapy Using Biomechanical Modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neylon, J; Min, Y; Qi, S

2014-06-15

Purpose: Deformable image registration (DIR) plays a pivotal role in head and neck adaptive radiotherapy but a systematic validation of DIR algorithms has been limited by a lack of quantitative high-resolution groundtruth. We address this limitation by developing a GPU-based framework that provides a systematic DIR validation by generating (a) model-guided synthetic CTs representing posture and physiological changes, and (b) model-guided landmark-based validation. Method: The GPU-based framework was developed to generate massive mass-spring biomechanical models from patient simulation CTs and contoured structures. The biomechanical model represented soft tissue deformations for known rigid skeletal motion. Posture changes were simulated by articulatingmore » skeletal anatomy, which subsequently applied elastic corrective forces upon the soft tissue. Physiological changes such as tumor regression and weight loss were simulated in a biomechanically precise manner. Synthetic CT data was then generated from the deformed anatomy. The initial and final positions for one hundred randomly-chosen mass elements inside each of the internal contoured structures were recorded as ground truth data. The process was automated to create 45 synthetic CT datasets for a given patient CT. For instance, the head rotation was varied between +/− 4 degrees along each axis, and tumor volumes were systematically reduced up to 30%. Finally, the original CT and deformed synthetic CT were registered using an optical flow based DIR. Results: Each synthetic data creation took approximately 28 seconds of computation time. The number of landmarks per data set varied between two and three thousand. The validation method is able to perform sub-voxel analysis of the DIR, and report the results by structure, giving a much more in depth investigation of the error. Conclusions: We presented a GPU based high-resolution biomechanical head and neck model to validate DIR algorithms by generating CT equivalent 3D volumes with simulated posture changes and physiological regression.« less

MO-B-BRC-04: MRI-Based Prostate HDR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mourtada, F.

2016-06-15

Brachytherapy has proven to be an effective treatment option for prostate cancer. Initially, prostate brachytherapy was delivered through permanently implanted low dose rate (LDR) radioactive sources; however, high dose rate (HDR) temporary brachytherapy for prostate cancer is gaining popularity. Needle insertion during prostate brachytherapy is most commonly performed under ultrasound (U/S) guidance; however, treatment planning may be performed utilizing several imaging modalities either in an intra- or post-operative setting. During intra-operative prostate HDR, the needles are imaged during implantation, and planning may be performed in real time. At present, the most common imaging modality utilized for intra-operative prostate HDR ismore » U/S. Alternatively, in the post-operative setting, following needle implantation, patients may be simulated with computed tomography (CT) or magnetic resonance imaging (MRI). Each imaging modality and workflow provides its share of benefits and limitations. Prostate HDR has been adopted in a number of cancer centers across the nation. In this educational session, we will explore the role of U/S, CT, and MRI in HDR prostate brachytherapy. Example workflows and operational details will be shared, and we will discuss how to establish a prostate HDR program in a clinical setting. Learning Objectives: Review prostate HDR techniques based on the imaging modality Discuss the challenges and pitfalls introduced by the three imagebased options for prostate HDR brachytherapy Review the QA process and learn about the development of clinical workflows for these imaging options at different institutions.« less

MO-B-BRC-02: Ultrasound Based Prostate HDR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Z.

2016-06-15

Brachytherapy has proven to be an effective treatment option for prostate cancer. Initially, prostate brachytherapy was delivered through permanently implanted low dose rate (LDR) radioactive sources; however, high dose rate (HDR) temporary brachytherapy for prostate cancer is gaining popularity. Needle insertion during prostate brachytherapy is most commonly performed under ultrasound (U/S) guidance; however, treatment planning may be performed utilizing several imaging modalities either in an intra- or post-operative setting. During intra-operative prostate HDR, the needles are imaged during implantation, and planning may be performed in real time. At present, the most common imaging modality utilized for intra-operative prostate HDR ismore » U/S. Alternatively, in the post-operative setting, following needle implantation, patients may be simulated with computed tomography (CT) or magnetic resonance imaging (MRI). Each imaging modality and workflow provides its share of benefits and limitations. Prostate HDR has been adopted in a number of cancer centers across the nation. In this educational session, we will explore the role of U/S, CT, and MRI in HDR prostate brachytherapy. Example workflows and operational details will be shared, and we will discuss how to establish a prostate HDR program in a clinical setting. Learning Objectives: Review prostate HDR techniques based on the imaging modality Discuss the challenges and pitfalls introduced by the three imagebased options for prostate HDR brachytherapy Review the QA process and learn about the development of clinical workflows for these imaging options at different institutions.« less

Accounting for patient size in the optimization of dose and image quality of pelvis cone beam CT protocols on the Varian OBI system.

PubMed

Wood, Tim J; Moore, Craig S; Horsfield, Carl J; Saunderson, John R; Beavis, Andrew W

2015-01-01

The purpose of this study was to develop size-based radiotherapy kilovoltage cone beam CT (CBCT) protocols for the pelvis. Image noise was measured in an elliptical phantom of varying size for a range of exposure factors. Based on a previously defined "small pelvis" reference patient and CBCT protocol, appropriate exposure factors for small, medium, large and extra-large patients were derived which approximate the image noise behaviour observed on a Philips CT scanner (Philips Medical Systems, Best, Netherlands) with automatic exposure control (AEC). Selection criteria, based on maximum tube current-time product per rotation selected during the radiotherapy treatment planning scan, were derived based on an audit of patient size. It has been demonstrated that 110 kVp yields acceptable image noise for reduced patient dose in pelvic CBCT scans of small, medium and large patients, when compared with manufacturer's default settings (125 kVp). Conversely, extra-large patients require increased exposure factors to give acceptable images. 57% of patients in the local population now receive much lower radiation doses, whereas 13% require higher doses (but now yield acceptable images). The implementation of size-based exposure protocols has significantly reduced radiation dose to the majority of patients with no negative impact on image quality. Increased doses are required on the largest patients to give adequate image quality. The development of size-based CBCT protocols that use the planning CT scan (with AEC) to determine which protocol is appropriate ensures adequate image quality whilst minimizing patient radiation dose.

SU-E-J-206: Adaptive Radiotherapy for Gynecological Malignancies with MRIGuided Cobolt-60 Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lamb, J; Kamrava, M; Agazaryan, N

Purpose: Even in the IMRT era, bowel toxicity and bone marrow irradiation remain concerns with pelvic irradiation. We examine the potential gain from an adaptive radiotherapy workflow for post-operative gynecological patients treated to pelvic targets including lymph nodes using MRI-guided Co-60 radiation therapy. Methods: An adaptive workflow was developed with the intent of minimizing time overhead of adaptive planning. A pilot study was performed using retrospectively analyzed images from one patient’s treatment. The patient’s treated plan was created using conventional PTV margins. Adaptive treatment was simulated on the patient’s first three fractions. The daily PTV was created by removing non-targetmore » tissue, including bone, muscle and bowel, from the initial PTV based on the daily MRI. The number of beams, beam angles, and optimization parameters were kept constant, and the plan was re-optimized. Normal tissue contours were not adjusted for the re-optimization, but were adjusted for evaluation of plan quality. Plan quality was evaluated based on PTV coverage and normal tissue DVH points per treatment protocol. Bowel was contoured as the entire bowel bag per protocol at our institution. Pelvic bone marrow was contoured per RTOG protocol 1203. Results: For the clinically treated plan, the volume of bowel receiving 45 Gy was 380 cc, 53% of the rectum received 30 Gy, 35% of the bladder received 45 Gy, and 28% of the pelvic bone marrow received 40 Gy. For the adaptive plans, the volume of bowel receiving 45 Gy was 175–201 cc, 55–62% of the rectum received 30 Gy, 21– 27% of the bladder received 45 Gy, and 13–17% of the pelvic bone marrow received 40 Gy. Conclusion: Adaptive planning led to a large reduction of bowel and bone marrow dose in this pilot study. Further study of on-line adaptive techniques for the radiotherapy of pelvic lymph nodes is warranted. Dr. Low is a member of the scientific advisory board of ViewRay, Inc.« less

Concept for individualized patient allocation: ReCompare--remote comparison of particle and photon treatment plans.

PubMed

Lühr, Armin; Löck, Steffen; Roth, Klaus; Helmbrecht, Stephan; Jakobi, Annika; Petersen, Jørgen B; Just, Uwe; Krause, Mechthild; Enghardt, Wolfgang; Baumann, Michael

2014-02-18

Identifying those patients who have a higher chance to be cured with fewer side effects by particle beam therapy than by state-of-the-art photon therapy is essential to guarantee a fair and sufficient access to specialized radiotherapy. The individualized identification requires initiatives by particle as well as non-particle radiotherapy centers to form networks, to establish procedures for the decision process, and to implement means for the remote exchange of relevant patient information. In this work, we want to contribute a practical concept that addresses these requirements. We proposed a concept for individualized patient allocation to photon or particle beam therapy at a non-particle radiotherapy institution that bases on remote treatment plan comparison. We translated this concept into the web-based software tool ReCompare (REmote COMparison of PARticlE and photon treatment plans). We substantiated the feasibility of the proposed concept by demonstrating remote exchange of treatment plans between radiotherapy institutions and the direct comparison of photon and particle treatment plans in photon treatment planning systems. ReCompare worked with several tested standard treatment planning systems, ensured patient data protection, and integrated in the clinical workflow. Our concept supports non-particle radiotherapy institutions with the patient-specific treatment decision on the optimal irradiation modality by providing expertise from a particle therapy center. The software tool ReCompare may help to improve and standardize this personalized treatment decision. It will be available from our website when proton therapy is operational at our facility.

Accuracy of volume measurement using 3D ultrasound and development of CT-3D US image fusion algorithm for prostate cancer radiotherapy.

PubMed

Baek, Jihye; Huh, Jangyoung; Kim, Myungsoo; Hyun An, So; Oh, Yoonjin; Kim, DongYoung; Chung, Kwangzoo; Cho, Sungho; Lee, Rena

2013-02-01

To evaluate the accuracy of measuring volumes using three-dimensional ultrasound (3D US), and to verify the feasibility of the replacement of CT-MR fusion images with CT-3D US in radiotherapy treatment planning. Phantoms, consisting of water, contrast agent, and agarose, were manufactured. The volume was measured using 3D US, CT, and MR devices. A CT-3D US and MR-3D US image fusion software was developed using the Insight Toolkit library in order to acquire three-dimensional fusion images. The quality of the image fusion was evaluated using metric value and fusion images. Volume measurement, using 3D US, shows a 2.8 ± 1.5% error, 4.4 ± 3.0% error for CT, and 3.1 ± 2.0% error for MR. The results imply that volume measurement using the 3D US devices has a similar accuracy level to that of CT and MR. Three-dimensional image fusion of CT-3D US and MR-3D US was successfully performed using phantom images. Moreover, MR-3D US image fusion was performed using human bladder images. 3D US could be used in the volume measurement of human bladders and prostates. CT-3D US image fusion could be used in monitoring the target position in each fraction of external beam radiation therapy. Moreover, the feasibility of replacing the CT-MR image fusion to the CT-3D US in radiotherapy treatment planning was verified.

Review of ultrasound image guidance in external beam radiotherapy: I. Treatment planning and inter-fraction motion management

NASA Astrophysics Data System (ADS)

Fontanarosa, Davide; van der Meer, Skadi; Bamber, Jeffrey; Harris, Emma; O'Shea, Tuathan; Verhaegen, Frank

2015-02-01

In modern radiotherapy, verification of the treatment to ensure the target receives the prescribed dose and normal tissues are optimally spared has become essential. Several forms of image guidance are available for this purpose. The most commonly used forms of image guidance are based on kilovolt or megavolt x-ray imaging. Image guidance can also be performed with non-harmful ultrasound (US) waves. This increasingly used technique has the potential to offer both anatomical and functional information. This review presents an overview of the historical and current use of two-dimensional and three-dimensional US imaging for treatment verification in radiotherapy. The US technology and the implementation in the radiotherapy workflow are described. The use of US guidance in the treatment planning process is discussed. The role of US technology in inter-fraction motion monitoring and management is explained, and clinical studies of applications in areas such as the pelvis, abdomen and breast are reviewed. A companion review paper (O’Shea et al 2015 Phys. Med. Biol. submitted) will extensively discuss the use of US imaging for intra-fraction motion quantification and novel applications of US technology to RT.

Review of ultrasound image guidance in external beam radiotherapy: I. Treatment planning and inter-fraction motion management.

PubMed

Fontanarosa, Davide; van der Meer, Skadi; Bamber, Jeffrey; Harris, Emma; O'Shea, Tuathan; Verhaegen, Frank

2015-02-07

In modern radiotherapy, verification of the treatment to ensure the target receives the prescribed dose and normal tissues are optimally spared has become essential. Several forms of image guidance are available for this purpose. The most commonly used forms of image guidance are based on kilovolt or megavolt x-ray imaging. Image guidance can also be performed with non-harmful ultrasound (US) waves. This increasingly used technique has the potential to offer both anatomical and functional information.This review presents an overview of the historical and current use of two-dimensional and three-dimensional US imaging for treatment verification in radiotherapy. The US technology and the implementation in the radiotherapy workflow are described. The use of US guidance in the treatment planning process is discussed. The role of US technology in inter-fraction motion monitoring and management is explained, and clinical studies of applications in areas such as the pelvis, abdomen and breast are reviewed. A companion review paper (O'Shea et al 2015 Phys. Med. Biol. submitted) will extensively discuss the use of US imaging for intra-fraction motion quantification and novel applications of US technology to RT.

Radiotherapy in Prostate Cancer Patients With Pelvic Lymphocele After Surgery: Clinical and Dosimetric Data of 30 Patients.

PubMed

Jereczek-Fossa, Barbara Alicja; Colangione, Sarah Pia; Fodor, Cristiana; Russo, Stefania; Cambria, Raffaella; Zerini, Dario; Bonora, Maria; Cecconi, Agnese; Vischioni, Barbara; Vavassori, Andrea; Matei, Deliu Victor; Bottero, Danilo; Brescia, Antonio; Musi, Gennaro; Mazzoleni, Federica; Orsi, Franco; Bonomo, Guido; De Cobelli, Ottavio; Orecchia, Roberto

2015-08-01

The purpose of the study was to evaluate the feasibility of irradiation after prostatectomy in the presence of asymptomatic pelvic lymphocele. The inclusion criteria for this study were: (1) patients referred for postoperative (adjuvant or salvage) intensity modulated radiotherapy (IMRT; 66-69 Gy in 30 fractions); (2) detection of postoperative pelvic lymphocele at the simulation computed tomography [CT] scan; (3) no clinical symptoms; and (4) written informed consent. Radiotherapy toxicity and occurrence of symptoms or complications of lymphocele were analyzed. Dosimetric data (IMRT plans) and the modification of lymphocele volume during radiotherapy (cone beam CT [CBCT] scan) were evaluated. Between January 2011 and July 2013, in 30 of 308 patients (10%) treated with radiotherapy after prostatectomy, pelvic lymphocele was detected on the simulation CT. The median lymphocele volume was 47 cm(3) (range, 6-467.3 cm(3)). Lymphocele was not included in planning target volume (PTV) in 8 cases (27%). Maximum dose to lymphocele was 57 Gy (range, 5.7-73.3 Gy). Radiotherapy was well tolerated. In all but 2 patients, lymphoceles remained asymptomatic. Lymphocele drainage-because of symptom occurrence-had to be performed in 2 patients during IMRT and in one patient, 7 weeks after IMRT. CBCT at the end of IMRT showed reduction in lymphocele volume and position compared with the initial data (median reduction of 37%), more pronounced in lymphoceles included in PTV. Radiotherapy after prostatectomy in the presence of pelvic asymptomatic lymphocele is feasible with acceptable acute and late toxicity. The volume of lymphoceles decreased during radiotherapy and this phenomenon might require intermediate radiotherapy plan evaluation. Copyright © 2015 Elsevier Inc. All rights reserved.

Comparison of onboard low-field magnetic resonance imaging versus onboard computed tomography for anatomy visualization in radiotherapy.

PubMed

Noel, Camille E; Parikh, Parag J; Spencer, Christopher R; Green, Olga L; Hu, Yanle; Mutic, Sasa; Olsen, Jeffrey R

2015-01-01

Onboard magnetic resonance imaging (OB-MRI) for daily localization and adaptive radiotherapy has been under development by several groups. However, no clinical studies have evaluated whether OB-MRI improves visualization of the target and organs at risk (OARs) compared to standard onboard computed tomography (OB-CT). This study compared visualization of patient anatomy on images acquired on the MRI-(60)Co ViewRay system to those acquired with OB-CT. Fourteen patients enrolled on a protocol approved by the Institutional Review Board (IRB) and undergoing image-guided radiotherapy for cancer in the thorax (n = 2), pelvis (n = 6), abdomen (n = 3) or head and neck (n = 3) were imaged with OB-MRI and OB-CT. For each of the 14 patients, the OB-MRI and OB-CT datasets were displayed side-by-side and independently reviewed by three radiation oncologists. Each physician was asked to evaluate which dataset offered better visualization of the target and OARs. A quantitative contouring study was performed on two abdominal patients to assess if OB-MRI could offer improved inter-observer segmentation agreement for adaptive planning. In total 221 OARs and 10 targets were compared for visualization on OB-MRI and OB-CT by each of the three physicians. The majority of physicians (two or more) evaluated visualization on MRI as better for 71% of structures, worse for 10% of structures, and equivalent for 14% of structures. 5% of structures were not visible on either. Physicians agreed unanimously for 74% and in majority for > 99% of structures. Targets were better visualized on MRI in 4/10 cases, and never on OB-CT. Low-field MR provides better anatomic visualization of many radiotherapy targets and most OARs as compared to OB-CT. Further studies with OB-MRI should be pursued.

A formulation of tissue- and water-equivalent materials using the stoichiometric analysis method for CT-number calibration in radiotherapy treatment planning.

PubMed

Yohannes, Indra; Kolditz, Daniel; Langner, Oliver; Kalender, Willi A

2012-03-07

Tissue- and water-equivalent materials (TEMs) are widely used in quality assurance and calibration procedures, both in radiodiagnostics and radiotherapy. In radiotherapy, particularly, the TEMs are often used for computed tomography (CT) number calibration in treatment planning systems. However, currently available TEMs may not be very accurate in the determination of the calibration curves due to their limitation in mimicking radiation characteristics of the corresponding real tissues in both low- and high-energy ranges. Therefore, we are proposing a new formulation of TEMs using a stoichiometric analysis method to obtain TEMs for the calibration purposes. We combined the stoichiometric calibration and the basic data method to compose base materials to develop TEMs matching standard real tissues from ICRU Report 44 and 46. First, the CT numbers of six materials with known elemental compositions were measured to get constants for the stoichiometric calibration. The results of the stoichiometric calibration were used together with the basic data method to formulate new TEMs. These new TEMs were scanned to validate their CT numbers. The electron density and the stopping power calibration curves were also generated. The absolute differences of the measured CT numbers of the new TEMs were less than 4 HU for the soft tissues and less than 22 HU for the bone compared to the ICRU real tissues. Furthermore, the calculated relative electron density and electron and proton stopping powers of the new TEMs differed by less than 2% from the corresponding ICRU real tissues. The new TEMs which were formulated using the proposed technique increase the simplicity of the calibration process and preserve the accuracy of the stoichiometric calibration simultaneously.

[Cervix cancer].

PubMed

Pointreau, Y; Ruffier Loubière, A; Denis, F; Barillot, I

2010-11-01

Cervix cancers declined in most developed countries in recent years, but remain, the third worldwide leading cause of cancer death in women. A precise staging, based on clinical exam, an abdominal and pelvic MRI, a possible PET-CT and a possible lymph node sampling is necessary to adapt the best therapeutic strategy. In France, the treatments of tumors of less than 4 cm without nodal involvement are often based on radiotherapy followed by surgery and, whereas tumors larger than 4 cm and involved nodes are treated with concurrent chemoradiotherapy. Based on an illustrated clinical case, indications, delineation, dosimetry and complications expected with radiotherapy are demonstrated. Copyright © 2010 Elsevier Masson SAS. All rights reserved.

Repeatability of dose painting by numbers treatment planning in prostate cancer radiotherapy based on multiparametric magnetic resonance imaging

NASA Astrophysics Data System (ADS)

van Schie, Marcel A.; Steenbergen, Peter; Viet Dinh, Cuong; Ghobadi, Ghazaleh; van Houdt, Petra J.; Pos, Floris J.; Heijmink, Stijn W. T. J. P.; van der Poel, Henk G.; Renisch, Steffen; Vik, Torbjørn; van der Heide, Uulke A.

2017-07-01

Dose painting by numbers (DPBN) refers to a voxel-wise prescription of radiation dose modelled from functional image characteristics, in contrast to dose painting by contours which requires delineations to define the target for dose escalation. The direct relation between functional imaging characteristics and DPBN implies that random variations in images may propagate into the dose distribution. The stability of MR-only prostate cancer treatment planning based on DPBN with respect to these variations is as yet unknown. We conducted a test-retest study to investigate the stability of DPBN for prostate cancer in a semi-automated MR-only treatment planning workflow. Twelve patients received a multiparametric MRI on two separate days prior to prostatectomy. The tumor probability (TP) within the prostate was derived from image features with a logistic regression model. Dose mapping functions were applied to acquire a DPBN prescription map that served to generate an intensity modulated radiation therapy (IMRT) treatment plan. Dose calculations were done on a pseudo-CT derived from the MRI. The TP and DPBN map and the IMRT dose distribution were compared between both MRI sessions, using the intraclass correlation coefficient (ICC) to quantify repeatability of the planning pipeline. The quality of each treatment plan was measured with a quality factor (QF). Median ICC values for the TP and DPBN map and the IMRT dose distribution were 0.82, 0.82 and 0.88, respectively, for linear dose mapping and 0.82, 0.84 and 0.94 for square root dose mapping. A median QF of 3.4% was found among all treatment plans. We demonstrated the stability of DPBN radiotherapy treatment planning in prostate cancer, with excellent overall repeatability and acceptable treatment plan quality. Using validated tumor probability modelling and simple dose mapping techniques it was shown that despite day-to-day variations in imaging data still consistent treatment plans were obtained.

Poster - 34: Clinical Implementation of Prone Breast Treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Runqing; Fleming, Katrina; Kobeleva, Sofya

2016-08-15

Purpose: Prone breast treatment is used to reduce acute and late toxicities for large or pendulous breast patients. This study developed and implemented the clinical workflow of prone breast radiotherapy treatment. Methods: Varian kVue Access360™ Prone Breast Couchtop was used as prone breast board. The treatment planning (TP)is performed in Eclipse TP system. TP comparisons between supine deep inspiration breathing hold (DIBH) and prone breast; prone forward field-in-field (FinF) planning and inverse IMRT planning were performed and discussed. For the daily setup, breast coverage was assessed in the room using light field and MV imaging was used at day 1more » and weekly. Results: The first ten patients are CT scanned and planned both supine and prone. The coverage was all excellent for supine DIBH plan and prone breast plan. The plan in the prone position demonstrated improvements in lung sparing comparing to the DIBH plan. Both forward FinF plan and inverse IMRT plan achieved acceptable coverage of the breast, and heart dose is comparable. Considering the daily setup variations and MLC leakage, forward FinF plan was recommended for routine clinical use. The procedure has been tested in phantom and patients were treated clinically. Conclusions: Prone breast irradiation has been advocated for women with large pendulous breasts in order to decrease acute and late toxicities. The workflow for prone breast radiation therapy has been developed and the technique is ready to treat patients.« less

A patch-based pseudo-CT approach for MRI-only radiotherapy in the pelvis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andreasen, Daniel, E-mail: dana@dtu.dk

Purpose: In radiotherapy based only on magnetic resonance imaging (MRI), knowledge about tissue electron densities must be derived from the MRI. This can be achieved by converting the MRI scan to the so-called pseudo-computed tomography (pCT). An obstacle is that the voxel intensities in conventional MRI scans are not uniquely related to electron density. The authors previously demonstrated that a patch-based method could produce accurate pCTs of the brain using conventional T{sub 1}-weighted MRI scans. The method was driven mainly by local patch similarities and relied on simple affine registrations between an atlas database of the co-registered MRI/CT scan pairsmore » and the MRI scan to be converted. In this study, the authors investigate the applicability of the patch-based approach in the pelvis. This region is challenging for a method based on local similarities due to the greater inter-patient variation. The authors benchmark the method against a baseline pCT strategy where all voxels inside the body contour are assigned a water-equivalent bulk density. Furthermore, the authors implement a parallelized approximate patch search strategy to speed up the pCT generation time to a more clinically relevant level. Methods: The data consisted of CT and T{sub 1}-weighted MRI scans of 10 prostate patients. pCTs were generated using an approximate patch search algorithm in a leave-one-out fashion and compared with the CT using frequently described metrics such as the voxel-wise mean absolute error (MAE{sub vox}) and the deviation in water-equivalent path lengths. Furthermore, the dosimetric accuracy was tested for a volumetric modulated arc therapy plan using dose–volume histogram (DVH) point deviations and γ-index analysis. Results: The patch-based approach had an average MAE{sub vox} of 54 HU; median deviations of less than 0.4% in relevant DVH points and a γ-index pass rate of 0.97 using a 1%/1 mm criterion. The patch-based approach showed a significantly better performance than the baseline water pCT in almost all metrics. The approximate patch search strategy was 70x faster than a brute-force search, with an average prediction time of 20.8 min. Conclusions: The authors showed that a patch-based method based on affine registrations and T{sub 1}-weighted MRI could generate accurate pCTs of the pelvis. The main source of differences between pCT and CT was positional changes of air pockets and body outline.« less

Automated algorithm for CBCT-based dose calculations of prostate radiotherapy with bilateral hip prostheses.

PubMed

Almatani, Turki; Hugtenburg, Richard P; Lewis, Ryan D; Barley, Susan E; Edwards, Mark A

2016-10-01

Cone beam CT (CBCT) images contain more scatter than a conventional CT image and therefore provide inaccurate Hounsfield units (HUs). Consequently, CBCT images cannot be used directly for radiotherapy dose calculation. The aim of this study is to enable dose calculations to be performed with the use of CBCT images taken during radiotherapy and evaluate the necessity of replanning. A patient with prostate cancer with bilateral metallic prosthetic hip replacements was imaged using both CT and CBCT. The multilevel threshold (MLT) algorithm was used to categorize pixel values in the CBCT images into segments of homogeneous HU. The variation in HU with position in the CBCT images was taken into consideration. This segmentation method relies on the operator dividing the CBCT data into a set of volumes where the variation in the relationship between pixel values and HUs is small. An automated MLT algorithm was developed to reduce the operator time associated with the process. An intensity-modulated radiation therapy plan was generated from CT images of the patient. The plan was then copied to the segmented CBCT (sCBCT) data sets with identical settings, and the doses were recalculated and compared. Gamma evaluation showed that the percentage of points in the rectum with γ < 1 (3%/3 mm) were 98.7% and 97.7% in the sCBCT using MLT and the automated MLT algorithms, respectively. Compared with the planning CT (pCT) plan, the MLT algorithm showed -0.46% dose difference with 8 h operator time while the automated MLT algorithm showed -1.3%, which are both considered to be clinically acceptable, when using collapsed cone algorithm. The segmentation of CBCT images using the method in this study can be used for dose calculation. For a patient with prostate cancer with bilateral hip prostheses and the associated issues with CT imaging, the MLT algorithms achieved a sufficient dose calculation accuracy that is clinically acceptable. The automated MLT algorithm reduced the operator time associated with implementing the MLT algorithm to achieve clinically acceptable accuracy. This saved time makes the automated MLT algorithm superior and easier to implement in the clinical setting. The MLT algorithm has been extended to the complex example of a patient with bilateral hip prostheses, which with the introduction of automation is feasible for use in adaptive radiotherapy, as an alternative to obtaining a new pCT and reoutlining the structures.

An efficient and robust MRI-guided radiotherapy planning approach for targeting abdominal organs and tumours in the mouse

PubMed Central

Bird, Luke; Tullis, Iain D. C.; Newman, Robert G.; Corroyer-Dulmont, Aurelien; Falzone, Nadia; Azad, Abul; Vallis, Katherine A.; Sansom, Owen J.; Muschel, Ruth J.; Vojnovic, Borivoj; Hill, Mark A.; Fokas, Emmanouil; Smart, Sean C.

2017-01-01

Introduction Preclinical CT-guided radiotherapy platforms are increasingly used but the CT images are characterized by poor soft tissue contrast. The aim of this study was to develop a robust and accurate method of MRI-guided radiotherapy (MR-IGRT) delivery to abdominal targets in the mouse. Methods A multimodality cradle was developed for providing subject immobilisation and its performance was evaluated. Whilst CT was still used for dose calculations, target identification was based on MRI. Each step of the radiotherapy planning procedure was validated initially in vitro using BANG gel dosimeters. Subsequently, MR-IGRT of normal adrenal glands with a size-matched collimated beam was performed. Additionally, the SK-N-SH neuroblastoma xenograft model and the transgenic KPC model of pancreatic ductal adenocarcinoma were used to demonstrate the applicability of our methods for the accurate delivery of radiation to CT-invisible abdominal tumours. Results The BANG gel phantoms demonstrated a targeting efficiency error of 0.56 ± 0.18 mm. The in vivo stability tests of body motion during MR-IGRT and the associated cradle transfer showed that the residual body movements are within this MR-IGRT targeting error. Accurate MR-IGRT of the normal adrenal glands with a size-matched collimated beam was confirmed by γH2AX staining. Regression in tumour volume was observed almost immediately post MR-IGRT in the neuroblastoma model, further demonstrating accuracy of x-ray delivery. Finally, MR-IGRT in the KPC model facilitated precise contouring and comparison of different treatment plans and radiotherapy dose distributions not only to the intra-abdominal tumour but also to the organs at risk. Conclusion This is, to our knowledge, the first study to demonstrate preclinical MR-IGRT in intra-abdominal organs. The proposed MR-IGRT method presents a state-of-the-art solution to enabling robust, accurate and efficient targeting of extracranial organs in the mouse and can operate with a sufficiently high throughput to allow fractionated treatments to be given. PMID:28453537

Cervical lymph node metastases of squamous cell carcinoma of unknown origin: the diagnostic value of FDG PET/CT and clinical outcome.

PubMed

Dale, Einar; Moan, Jon M; Osnes, Terje A; Bogsrud, Trond V

2017-02-01

FDG PET/CT is perceived as a valuable diagnostic tool in addition to the standard diagnostic workup for patients with isolated neck lymph nodes of squamous cell carcinoma of unknown primary (SCCUP). For patients with SCCUP intended for primary radiotherapy, we hypothesize that the previously reported FDG PET/CT detection rates are too high. From 2008 to 2015, 30 SCCUP patients were examined with FDG PET/CT. The objective of the FDG PET/CT examination was twofold: (1) improve the radiotherapy target definition, and (2) identify the primary cancer. Before the FDG PET/CT, the patients had been through a standard workup consisting of CT of the neck and chest, examination with flexible endoscopy with patient awake, panendoscopy and examination under general anesthesia, tonsillectomy and sometimes blind sampling biopsies, and MRI (floor of the mouth). All FDG PET/CTs were performed applying a flat table, head support and fixation mask as part of the radiotherapy treatment planning. Diagnostic CT with contrast was an integrated part of the PET/CT examination. Only 1/30 patients (cancer of the vallecula) had their primary cancer detected by FDG PET/CT. In addition, a non-biopsied patient with high uptake in the ipsilateral palatine tonsil was included, giving a detection rate of ≤7 % (95 % CI 2-21 %). In this retrospective study, we found that the FDG PET/CT detection rate of the primary for SCCUP patients is lower than previously reported. It is questionable whether FDG PET/CT is necessary for these patients when improved, advanced workup is available.

A 3D global-to-local deformable mesh model based registration and anatomy-constrained segmentation method for image guided prostate radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou Jinghao; Kim, Sung; Jabbour, Salma

2010-03-15

Purpose: In the external beam radiation treatment of prostate cancers, successful implementation of adaptive radiotherapy and conformal radiation dose delivery is highly dependent on precise and expeditious segmentation and registration of the prostate volume between the simulation and the treatment images. The purpose of this study is to develop a novel, fast, and accurate segmentation and registration method to increase the computational efficiency to meet the restricted clinical treatment time requirement in image guided radiotherapy. Methods: The method developed in this study used soft tissues to capture the transformation between the 3D planning CT (pCT) images and 3D cone-beam CTmore » (CBCT) treatment images. The method incorporated a global-to-local deformable mesh model based registration framework as well as an automatic anatomy-constrained robust active shape model (ACRASM) based segmentation algorithm in the 3D CBCT images. The global registration was based on the mutual information method, and the local registration was to minimize the Euclidian distance of the corresponding nodal points from the global transformation of deformable mesh models, which implicitly used the information of the segmented target volume. The method was applied on six data sets of prostate cancer patients. Target volumes delineated by the same radiation oncologist on the pCT and CBCT were chosen as the benchmarks and were compared to the segmented and registered results. The distance-based and the volume-based estimators were used to quantitatively evaluate the results of segmentation and registration. Results: The ACRASM segmentation algorithm was compared to the original active shape model (ASM) algorithm by evaluating the values of the distance-based estimators. With respect to the corresponding benchmarks, the mean distance ranged from -0.85 to 0.84 mm for ACRASM and from -1.44 to 1.17 mm for ASM. The mean absolute distance ranged from 1.77 to 3.07 mm for ACRASM and from 2.45 to 6.54 mm for ASM. The volume overlap ratio ranged from 79% to 91% for ACRASM and from 44% to 80% for ASM. These data demonstrated that the segmentation results of ACRASM were in better agreement with the corresponding benchmarks than those of ASM. The developed registration algorithm was quantitatively evaluated by comparing the registered target volumes from the pCT to the benchmarks on the CBCT. The mean distance and the root mean square error ranged from 0.38 to 2.2 mm and from 0.45 to 2.36 mm, respectively, between the CBCT images and the registered pCT. The mean overlap ratio of the prostate volumes ranged from 85.2% to 95% after registration. The average time of the ACRASM-based segmentation was under 1 min. The average time of the global transformation was from 2 to 4 min on two 3D volumes and the average time of the local transformation was from 20 to 34 s on two deformable superquadrics mesh models. Conclusions: A novel and fast segmentation and deformable registration method was developed to capture the transformation between the planning and treatment images for external beam radiotherapy of prostate cancers. This method increases the computational efficiency and may provide foundation to achieve real time adaptive radiotherapy.« less

Using PACS and wavelet-based image compression in a wide-area network to support radiation therapy imaging applications for satellite hospitals

NASA Astrophysics Data System (ADS)

Smith, Charles L.; Chu, Wei-Kom; Wobig, Randy; Chao, Hong-Yang; Enke, Charles

1999-07-01

An ongoing PACS project at our facility has been expanded to include providing and managing images used for routine clinical operation of the department of radiation oncology. The intent of our investigation has been to enable out clinical radiotherapy service to enter the tele-medicine environment through the use of a PACS system initially implemented in the department of radiology. The backbone for the imaging network includes five CT and three MR scanners located across three imaging centers. A PC workstation in the department of radiation oncology was used to transmit CT imags to a satellite facility located approximately 60 miles from the primary center. Chest CT images were used to analyze network transmission performance. Connectivity established between the primary department and satellite has fulfilled all image criteria required by the oncologist. Establishing the link tot eh oncologist at the satellite diminished bottlenecking of imaging related tasks at the primary facility due to physician absence. A 30:1 compression ratio using a wavelet-based algorithm provided clinically acceptable images treatment planning. Clinical radiotherapy images can be effectively managed in a wide- area-network to link satellite facilities to larger clinical centers.

SU-E-J-265: Feasibility Study of Texture Analysis for Prognosis of Local Tumor Recurrence Within 5-Years for Pharyngeal-Laryngeal Carcinoma Patients Received Radiotherapy Treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, W; Tu, S

Purpose: Pharyngeal and laryngeal carcinomas (PLC) are among the top leading cancers in Asian populations. Typically the tumor may recur and progress in a short period of time if radiotherapy fails to deliver a successful treatment. Here we used image texture features extracted from images of computed tomography (CT) planning and conducted a retrospective study to evaluate whether texture analysis is a feasible approach to predict local tumor recurrence for PLC patients received radiotherapy treatment. Methods: CT planning images of 100 patients with PLC treated by radiotherapy at our facility between 2001 and 2010 are collected. These patients were receivedmore » two separate CT scans, before and mid-course of the treatment delivery. Before the radiotherapy, a CT scanning was used for the first treatment planning. A total of 30 fractions were used in the treatment and patients were scanned with a second CT around the end of the fifteenth delivery for an adaptive treatment planning. Only patients who were treated with intensity modulated radiation therapy and RapidArc were selected. Treatment planning software of Eclipse was used. The changes of texture parameters between two CT acquisitions were computed to determine whether they were correlated to the local tumor recurrence. The following texture parameters were used in the preliminary assessment: mean, variance, standard deviation, skewness, kurtosis, energy, entropy, inverse difference moment, cluster shade, inertia, cluster prominence, gray-level co-occurrence matrix, and gray-level run-length matrix. The study was reviewed and approved by the committee of our institutional review board. Results: Our calculations suggested the following texture parameters were correlated with the local tumor recurrence: skewness, kurtosis, entropy, and inertia (p<0.0.05). Conclusion: The preliminary results were positive. However some works remain crucial to be completed, including addition of texture parameters for different image features, sensitivity of tumor segmentation variations, and effect of image filtering.« less

SU-D-202-04: Validation of Deformable Image Registration Algorithms for Head and Neck Adaptive Radiotherapy in Routine Clinical Setting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, L; Pi, Y; Chen, Z

2016-06-15

Purpose: To evaluate the ROI contours and accumulated dose difference using different deformable image registration (DIR) algorithms for head and neck (H&N) adaptive radiotherapy. Methods: Eight H&N cancer patients were randomly selected from the affiliated hospital. During the treatment, patients were rescanned every week with ROIs well delineated by radiation oncologist on each weekly CT. New weekly treatment plans were also re-designed with consistent dose prescription on the rescanned CT and executed for one week on Siemens CT-on-rails accelerator. At the end, we got six weekly CT scans from CT1 to CT6 including six weekly treatment plans for each patient.more » The primary CT1 was set as the reference CT for DIR proceeding with the left five weekly CTs using ANACONDA and MORFEUS algorithms separately in RayStation and the external skin ROI was set to be the controlling ROI both. The entire calculated weekly dose were deformed and accumulated on corresponding reference CT1 according to the deformation vector field (DVFs) generated by the two different DIR algorithms respectively. Thus we got both the ANACONDA-based and MORFEUS-based accumulated total dose on CT1 for each patient. At the same time, we mapped the ROIs on CT1 to generate the corresponding ROIs on CT6 using ANACONDA and MORFEUS DIR algorithms. DICE coefficients between the DIR deformed and radiation oncologist delineated ROIs on CT6 were calculated. Results: For DIR accumulated dose, PTV D95 and Left-Eyeball Dmax show significant differences with 67.13 cGy and 109.29 cGy respectively (Table1). For DIR mapped ROIs, PTV, Spinal cord and Left-Optic nerve show difference with −0.025, −0.127 and −0.124 (Table2). Conclusion: Even two excellent DIR algorithms can give divergent results for ROI deformation and dose accumulation. As more and more TPS get DIR module integrated, there is an urgent need to realize the potential risk using DIR in clinical.« less

Survey on deep learning for radiotherapy.

PubMed

Meyer, Philippe; Noblet, Vincent; Mazzara, Christophe; Lallement, Alex

2018-07-01

More than 50% of cancer patients are treated with radiotherapy, either exclusively or in combination with other methods. The planning and delivery of radiotherapy treatment is a complex process, but can now be greatly facilitated by artificial intelligence technology. Deep learning is the fastest-growing field in artificial intelligence and has been successfully used in recent years in many domains, including medicine. In this article, we first explain the concept of deep learning, addressing it in the broader context of machine learning. The most common network architectures are presented, with a more specific focus on convolutional neural networks. We then present a review of the published works on deep learning methods that can be applied to radiotherapy, which are classified into seven categories related to the patient workflow, and can provide some insights of potential future applications. We have attempted to make this paper accessible to both radiotherapy and deep learning communities, and hope that it will inspire new collaborations between these two communities to develop dedicated radiotherapy applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

SU-F-T-427: Utilization and Evaluation of Diagnostic CT Imaging with MAR Technique for Radiation Therapy Treatment Planning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, M; Foster, R; Parks, H

Purpose: The objective was to utilize and evaluate diagnostic CT-MAR technique for radiation therapy treatment planning. Methods: A Toshiba-diagnostic-CT acquisition with SEMAR(Single-energy-MAR)-algorism was performed to make the metal-artifact-reduction (MAR) for patient treatment planning. CT-imaging datasets with and without SEMAR were taken on a Catphan-phantom. Two sets of CT-numbers were calibrated with the relative electron densities (RED). A tissue characterization phantom with Gammex various simulating material rods was used to establish the relationship between known REDs and corresponding CT-numbers. A GE-CT-sim acquisition was taken on the Catphan for comparison. A patient with bilateral hip arthroplasty was scanned in the radiotherapy CT-simmore » and the diagnostic SEMAR-CT on a flat panel. The derived SEMAR images were used as a primary CT dataset to create contours for the target, critical-structures, and for planning. A deformable registration was performed with VelocityAI to track voxel changes between SEMAR and CT-sim images. The SEMAR-CT images with minimal artifacts and high quality of geometrical and spatial integrity were employed for a treatment plan. Treatment-plans were evaluated based on deformable registration of SEMAR-CT and CT-sim dataset with assigned CT-numbers in the metal artifact regions in Eclipse v11 TPS. Results: The RED and CT-number relationships were consistent for the datasets in CT-sim and CT’s with and without SEMAR. SEMAR datasets with high image quality were used for PTV and organ delineation in the treatment planning process. For dose distribution to the PTV through the DVH analysis, the plan using CT-sim with the assigned CT-number showed a good agreement to those on deformable CT-SEMAR. Conclusion: A diagnostic-CT with MAR-algorithm can be utilized for radiotherapy treatment planning with CT-number calibrated to the RED. Treatment planning comparison and DVH shows a good agreement in the PTV and critical organs between the plans on CT-sim with assigned CT-number and the deformable SEMAR CT datasets.« less

Treatment planning and delivery of involved field radiotherapy in advanced Hodgkin's disease: results from a questionnaire-based audit for the UK Stanford V regimen vs ABVD clinical trial quality assurance programme (ISRCTN 64141244).

PubMed

Diez, P; Hoskin, P J; Aird, E G A

2007-10-01

This questionnaire forms the basis of the quality assurance (QA) programme for the UK randomized Phase III study of the Stanford V regimen versus ABVD for treatment of advanced Hodgkin's disease to assess differences between participating centres in treatment planning and delivery of involved-field radiotherapy for Hodgkin's lymphoma The questionnaire, which was circulated amongst 42 participating centres, consisted of seven sections: target volume definition and dose prescription; critical structures; patient positioning and irradiation techniques; planning; dose calculation; verification; and future developments The results are based on 25 responses. One-third plan using CT alone, one-third use solely the simulator and the rest individualize, depending on disease site. Eleven centres determine a dose distribution for each patient. Technique depends on disease site and whether CT or simulator planning is employed. Most departments apply isocentric techniques and use immobilization and customized shielding. In vivo dosimetry is performed in 7 centres and treatment verification occurs in 24 hospitals. In conclusion, the planning and delivery of treatment for lymphoma patients varies across the country. Conventional planning is still widespread but most centres are moving to CT-based planning and virtual simulation with extended use of immobilization, customized shielding and compensation.

Application of EARL (ResEARch 4 Life®) protocols for [18F]FDG-PET/CT clinical and research studies. A roadmap towards exact recovery coefficient

NASA Astrophysics Data System (ADS)

Balcerzyk, Marcin; Fernández-López, Rosa; Parrado-Gallego, Ángel; Pachón-Garrudo, Víctor Manuel; Chavero-Royan, José; Hevilla, Juan; Jiménez-Ortega, Elisa; Leal, Antonio

2017-11-01

Tumour uptake value is a critical result in [18F]FDG-PET/CT ([18F]fluorodeoxyglucose) quantitative scans such as the dose prescription for radiotherapy and oncology. The quantification is highly dependent on the protocol of acquisition and reconstruction of the image, especially in low activity tumours. During adjusting acquisition and reconstruction protocols available in our Siemens Biograph mCT scanner for EARL (ResEARch 4 Life®) [18F]FDG-PET/CT accreditation requirements, we developed reconstruction protocols which will be used in PET based radiotherapy planning able to reduce inter-/intra-institute variability in Standard Uptake Value (SUV) results, and to bring Recovery Coefficient to 1 as close as possible for Image Quality NEMA 2007 phantom. Primary and secondary tumours from two patients were assessed by four independent evaluators. The influence of reconstruction protocols on tumour clinical assessment was presented. We proposed the improvement route for EARL accredited protocols so that they may be developed in classes to take advantage of scanner possibilities. The application of optimized reconstruction protocol eliminates the need of partial volume corrections.

Comparison of manual and automatic MR‐CT registration for radiotherapy of prostate cancer

PubMed Central

Carl, Jesper; Østergaard, Lasse Riis

2016-01-01

In image‐guided radiotherapy (IGRT) of prostate cancer, delineation of the clinical target volume (CTV) often relies on magnetic resonance (MR) because of its good soft‐tissue visualization. Registration of MR and computed tomography (CT) is required in order to add this accurate delineation to the dose planning CT. An automatic approach for local MR‐CT registration of the prostate has previously been developed using a voxel property‐based registration as an alternative to a manual landmark‐based registration. The aim of this study is to compare the two registration approaches and to investigate the clinical potential for replacing the manual registration with the automatic registration. Registrations and analysis were performed for 30 prostate cancer patients treated with IGRT using a Ni‐Ti prostate stent as a fiducial marker. The comparison included computing translational and rotational differences between the approaches, visual inspection, and computing the overlap of the CTV. The computed mean translational difference was 1.65, 1.60, and 1.80 mm and the computed mean rotational difference was 1.51°, 3.93°, and 2.09° in the superior/inferior, anterior/posterior, and medial/lateral direction, respectively. The sensitivity of overlap was 87%. The results demonstrate that the automatic registration approach performs registrations comparable to the manual registration. PACS number(s): 87.57.nj, 87.61.‐c, 87.57.Q‐, 87.56.J‐ PMID:27167285

Quantitative effect of combined chemotherapy and fractionated radiotherapy on the incidence of radiation-induced lung damage: A prospective clinical study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mah, K.; Van Dyk, J.; Braban, L.E.

1994-02-01

The objective of this work was to assess the incidence of radiological changes compatible with radiation-induced lung damage as determined by computed tomography (CT), and subsequently calculate the dose effect factors (DEF) for specified chemotherapeutic regimens. Radiation treatments were administered once daily, 5 days-per-week. Six clinical protocols were evaluated: ABVD (adriamycin, bleomycin, vincristine, and DTIC) followed by 35 Gy in 20 fractions; MOPP (nitrogen mustard, vincristine, procarbazine, and prednisone) followed by 35 Gy in 20; MOPP/ABVD followed by 35 Gy in 20; CAV (cyclophosphamide, adriamycin, and vincristine) followed by 25 Gy in 10; and 5-FU (5-fluorouracil) concurrent with either 50-52more » Gy in 20-21 or 30-36 Gy in 10-15 fractions. CT examinations were taken before and at predetermined intervals following radiotherapy. CT evidence for the development of radiation-induced damage was defined as an increase in lung density within the irradiated volume. The radiation dose to lung was calculated using a CT-based algorithm to account for tissue inhomogeneities. Different fractionation schedules were converted using two isoeffect models, the estimated single dose (ED) and the normalized total dose (NTD). The actuarial incidence of radiological pneumonitis was 71% for the ABVD, 49% for MOPP, 52% for MOPP/ABVD, 67% for CAV, 73% for 5-FU radical, and 58% for 5-FU palliative protocols. Depending on the isoeffect model selected and the method of analysis, the DEF was 1.11-1.14 for the ABVD, 0.96-0.97 for the MOPP, 0.96-1.02 for the MOPP/ABVD, 1.03-1.10 for the CAV, 0.74-0.79 for the 5-FU radical, and 0.94 for the 5-FU palliative protocols. DEF were measured by comparing the incidence of CT-observed lung damage in patients receiving chemotherapy and radiotherapy to those receiving radiotherapy alone. The addition of ABVD or CAV appeared to reduce the tolerance of lung to radiation. 40 refs., 3 figs., 3 tabs.« less

Pancreatic Cancer Tumor Size on CT Scan Versus Pathologic Specimen: Implications for Radiation Treatment Planning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arvold, Nils D.; Niemierko, Andrzej; Mamon, Harvey J.

2011-08-01

Purpose: Pancreatic cancer primary tumor size measurements are often discordant between computed tomography (CT) and pathologic specimen after resection. Dimensions of the primary tumor are increasingly relevant in an era of highly conformal radiotherapy. Methods and Materials: We retrospectively evaluated 97 consecutive patients with resected pancreatic cancer at two Boston hospitals. All patients had CT scans before surgical resection. Primary endpoints were maximum dimension (in millimeters) of the primary tumor in any direction as reported by the radiologist on CT and by the pathologist for the resected gross fresh specimen. Endoscopic ultrasound (EUS) findings were analyzed if available. Results: Ofmore » the patients, 87 (90%) had preoperative CT scans available for review and 46 (47%) had EUS. Among proximal tumors (n = 69), 40 (58%) had pathologic duodenal invasion, which was seen on CT in only 3 cases. The pathologic tumor size was a median of 7 mm larger compared with CT size for the same patient (range, -15 to 43 mm; p < 0.0001), with 73 patients (84%) having a primary tumor larger on pathology than CT. Endoscopic ultrasound was somewhat more accurate, with pathologic tumor size being a median of only 5 mm larger compared with EUS size (range, -15 to 35 mm; p = 0.0003). Conclusions: Computed tomography scans significantly under-represent pancreatic cancer tumor size compared with pathologic specimens in resectable cases. We propose a clinical target volume expansion formula for the primary tumor based on our data. The high rate of pathologic duodenal invasion suggests a risk of duodenal undercoverage with highly conformal radiotherapy.« less

SU-E-J-36: A Flexible Integration of Key Technologies in Image-Guided Radiotherapy for Accurate Radiotherapy System (ARTS-IGRT).

PubMed

Jia, J; Liu, F; Ren, Q; Pei, X; Cao, R; Wu, Y

2012-06-01

Image-guided radiotherapy (IGRT) is becoming increasingly important in the planning and delivery of radiotherapy. With the aim of implementing the key technologies in a flexible and integrated way in IGRT for accurate radiotherapy system (ARTS), a prototype system named as ARTS-IGRT was designed and completed to apply main principles in image-guided radiotherapy. The basic workflow of the ARTS-IGRT software was completed with five functional modules including management of patient information, X-ray image acquisition, 2D/2D anatomy match, 2D/3D match as well as marker-based match. For 2D/2D match, an image registration method was proposed based on maximization of mutual information with multi-resolution and regions of interest. For the 2D/3D registration, optimizations have been employed to improve the existing digitally reconstructed radiography generation algorithm based on ray-casting, and also an image registration method based on implanted markers with different numbers was adopted for 3D/3D match. In additional, the kV X-Ray imaging on rail device was finished for a better internal anatomy image checking at any angle. Together with an infrared device, a positioning and tracking system was developed as well for accurate patient setup and motion monitoring during each treatment. A lot of tests were carried out based on the head phantom to testify the availability of the improved algorithms. Compared with a set of controlled experiments adopted on the released commercial IGRT platform in the hospital, the functions of both software and hardware were testified comprehensively. The results showed a validity verification of ARTS-IGRT. The accuracy and efficiency of ARTS-IGRT on both software and hardware proved to be valid. And also with a flexible and user-friendly interface it can meet the principles of clinical radiotherapy practice. Supported by the Natural Science Foundation of Anhui Province (11040606Q55) and the National Natural Science Foundation of China (30900386). © 2012 American Association of Physicists in Medicine.

Using injectable hydrogel markers to assess resimulation for boost target volume definition in a patient undergoing whole-breast radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patel, Henal; Goyal, Sharad; Kim, Leonard, E-mail: kimlh@rutgers.edu

Several publications have recommended that patients undergoing whole-breast radiotherapy be resimulated for boost planning. The rationale for this is that the seroma may be smaller when compared with the initial simulation. However, the decision remains whether to use the earlier or later images to define an appropriate boost target volume. A patient undergoing whole-breast radiotherapy had new, injectable, temporary hydrogel fiducial markers placed 1 to 3 cm from the seroma at the time of initial simulation. The patient was resimulated 4.5 weeks later for conformal photon boost planning. Computed tomography (CT) scans acquired at the beginning and the end ofmore » whole-breast radiotherapy showed that shrinkage of the lumpectomy cavity was not matched by a corresponding reduction in the surrounding tissue volume, as demarcated by hydrogel markers. This observation called into question the usual interpretation of cavity shrinkage for boost target definition. For this patient, it was decided to define the boost target volume on the initial planning CT instead of the new CT.« less

The emerging potential of magnetic resonance imaging in personalizing radiotherapy for head and neck cancer: an oncologist's perspective.

PubMed

Wong, Kee H; Panek, Rafal; Bhide, Shreerang A; Nutting, Christopher M; Harrington, Kevin J; Newbold, Katie L

2017-03-01

Head and neck cancer (HNC) is a challenging tumour site for radiotherapy delivery owing to its complex anatomy and proximity to organs at risk (OARs) such as the spinal cord and optic apparatus. Despite significant advances in radiotherapy planning techniques, radiation-induced morbidities remain substantial. Further improvement would require high-quality imaging and tailored radiotherapy based on intratreatment response. For these reasons, the use of MRI in radiotherapy planning for HNC is rapidly gaining popularity. MRI provides superior soft-tissue contrast in comparison with CT, allowing better definition of the tumour and OARs. The lack of additional radiation exposure is another attractive feature for intratreatment monitoring. In addition, advanced MRI techniques such as diffusion-weighted, dynamic contrast-enhanced and intrinsic susceptibility-weighted MRI techniques are capable of characterizing tumour biology further by providing quantitative functional parameters such as tissue cellularity, vascular permeability/perfusion and hypoxia. These functional parameters are known to have radiobiological relevance, which potentially could guide treatment adaptation based on their changes prior to or during radiotherapy. In this article, we first present an overview of the applications of anatomical MRI sequences in head and neck radiotherapy, followed by the potentials and limitations of functional MRI sequences in personalizing therapy.

The emerging potential of magnetic resonance imaging in personalizing radiotherapy for head and neck cancer: an oncologist's perspective

PubMed Central

Panek, Rafal; Bhide, Shreerang A; Nutting, Christopher M; Harrington, Kevin J; Newbold, Katie L

2017-01-01

Head and neck cancer (HNC) is a challenging tumour site for radiotherapy delivery owing to its complex anatomy and proximity to organs at risk (OARs) such as the spinal cord and optic apparatus. Despite significant advances in radiotherapy planning techniques, radiation-induced morbidities remain substantial. Further improvement would require high-quality imaging and tailored radiotherapy based on intratreatment response. For these reasons, the use of MRI in radiotherapy planning for HNC is rapidly gaining popularity. MRI provides superior soft-tissue contrast in comparison with CT, allowing better definition of the tumour and OARs. The lack of additional radiation exposure is another attractive feature for intratreatment monitoring. In addition, advanced MRI techniques such as diffusion-weighted, dynamic contrast-enhanced and intrinsic susceptibility-weighted MRI techniques are capable of characterizing tumour biology further by providing quantitative functional parameters such as tissue cellularity, vascular permeability/perfusion and hypoxia. These functional parameters are known to have radiobiological relevance, which potentially could guide treatment adaptation based on their changes prior to or during radiotherapy. In this article, we first present an overview of the applications of anatomical MRI sequences in head and neck radiotherapy, followed by the potentials and limitations of functional MRI sequences in personalizing therapy. PMID:28256151

18F-fluorodeoxyglucose positron emission tomography/computed tomography-based radiotherapy target volume definition in non-small-cell lung cancer: delineation by radiation oncologists vs. joint outlining with a PET radiologist?

PubMed

Hanna, Gerard G; Carson, Kathryn J; Lynch, Tom; McAleese, Jonathan; Cosgrove, Vivian P; Eakin, Ruth L; Stewart, David P; Zatari, Ashraf; O'Sullivan, Joe M; Hounsell, Alan R

2010-11-15

(18)F-Fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) has benefits in target volume (TV) definition in radiotherapy treatment planning (RTP) for non-small-cell lung cancer (NSCLC); however, an optimal protocol for TV delineation has not been determined. We investigate volumetric and positional variation in gross tumor volume (GTV) delineation using a planning PET/CT among three radiation oncologists and a PET radiologist. RTP PET/CT scans were performed on 28 NSCLC patients (Stage IA-IIIB) of which 14 patients received prior induction chemotherapy. Three radiation oncologists and one PET radiologist working with a fourth radiation oncologist independently delineated the GTV on CT alone (GTV(CT)) and on fused PET/CT images (GTV(PETCT)). The mean percentage volume change (PVC) between GTV(CT) and GTV(PETCT) for the radiation oncologists and the PVC between GTV(CT) and GTV(PETCT) for the PET radiologist were compared using the Wilcoxon signed-rank test. Concordance index (CI) was used to assess both positional and volume change between GTV(CT) and GTV(PETCT) in a single measurement. For all patients, a significant difference in PVC from GTV(CT) to GTV(PETCT) exists between the radiation oncologist (median, 5.9%), and the PET radiologist (median, -0.4%, p = 0.001). However, no significant difference in median concordance index (comparing GTV(CT) and GTV(FUSED) for individual cases) was observed (PET radiologist = 0.73; radiation oncologists = 0.66; p = 0.088). Percentage volume changes from GTV(CT) to GTV(PETCT) were lower for the PET radiologist than for the radiation oncologists, suggesting a lower impact of PET/CT in TV delineation for the PET radiologist than for the oncologists. Guidelines are needed to standardize the use of PET/CT for TV delineation in RTP. Copyright © 2010 Elsevier Inc. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dogan, N; Padgett, K; Evans, J

Purpose: Adaptive Radiotherapy (ART) with frequent CT imaging has been used to improve dosimetric accuracy by accounting for anatomical variations, such as primary tumor shrinkage and/or body weight loss, in Head and Neck (H&N) patients. In most ART strategies, the difference between the planned and the delivered dose is estimated by generating new plans on repeated CT scans using dose-volume constraints used with the initial planning CT without considering already delivered dose. The aim of this study was to assess the dosimetric gains achieved by re-planning based on prior dose by comparing them to re-planning not based-on prior dose formore » H&N patients. Methods: Ten locally-advanced H&N cancer patients were selected for this study. For each patient, six weekly CT imaging were acquired during the course of radiotherapy. PTVs, parotids, cord, brainstem, and esophagus were contoured on both planning and six weekly CT images. ART with weekly re-plans were done by two strategies: 1) Generating a new optimized IMRT plan without including prior dose from previous fractions (NoPriorDose) and 2) Generating a new optimized IMRT plan based on the prior dose given from previous fractions (PriorDose). Deformable image registration was used to accumulate the dose distributions between planning and six weekly CT scans. The differences in accumulated doses for both strategies were evaluated using the DVH constraints for all structures. Results: On average, the differences in accumulated doses for PTV1, PTV2 and PTV3 for NoPriorDose and PriorDose strategies were <2%. The differences in Dmean to the cord and brainstem were within 3%. The esophagus Dmean was reduced by 2% using PriorDose. PriorDose strategy, however, reduced the left parotid D50 and Dmean by 15% and 14% respectively. Conclusion: This study demonstrated significant parotid sparing, potentially reducing xerostomia, by using ART with IMRT optimization based on prior dose for weekly re-planning of H&N cancer patients.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zoberi, J.

Brachytherapy has proven to be an effective treatment option for prostate cancer. Initially, prostate brachytherapy was delivered through permanently implanted low dose rate (LDR) radioactive sources; however, high dose rate (HDR) temporary brachytherapy for prostate cancer is gaining popularity. Needle insertion during prostate brachytherapy is most commonly performed under ultrasound (U/S) guidance; however, treatment planning may be performed utilizing several imaging modalities either in an intra- or post-operative setting. During intra-operative prostate HDR, the needles are imaged during implantation, and planning may be performed in real time. At present, the most common imaging modality utilized for intra-operative prostate HDR ismore » U/S. Alternatively, in the post-operative setting, following needle implantation, patients may be simulated with computed tomography (CT) or magnetic resonance imaging (MRI). Each imaging modality and workflow provides its share of benefits and limitations. Prostate HDR has been adopted in a number of cancer centers across the nation. In this educational session, we will explore the role of U/S, CT, and MRI in HDR prostate brachytherapy. Example workflows and operational details will be shared, and we will discuss how to establish a prostate HDR program in a clinical setting. Learning Objectives: Review prostate HDR techniques based on the imaging modality Discuss the challenges and pitfalls introduced by the three imagebased options for prostate HDR brachytherapy Review the QA process and learn about the development of clinical workflows for these imaging options at different institutions.« less

Accounting for patient size in the optimization of dose and image quality of pelvis cone beam CT protocols on the Varian OBI system

PubMed Central

Moore, Craig S; Horsfield, Carl J; Saunderson, John R; Beavis, Andrew W

2015-01-01

Objective: The purpose of this study was to develop size-based radiotherapy kilovoltage cone beam CT (CBCT) protocols for the pelvis. Methods: Image noise was measured in an elliptical phantom of varying size for a range of exposure factors. Based on a previously defined “small pelvis” reference patient and CBCT protocol, appropriate exposure factors for small, medium, large and extra-large patients were derived which approximate the image noise behaviour observed on a Philips CT scanner (Philips Medical Systems, Best, Netherlands) with automatic exposure control (AEC). Selection criteria, based on maximum tube current–time product per rotation selected during the radiotherapy treatment planning scan, were derived based on an audit of patient size. Results: It has been demonstrated that 110 kVp yields acceptable image noise for reduced patient dose in pelvic CBCT scans of small, medium and large patients, when compared with manufacturer's default settings (125 kVp). Conversely, extra-large patients require increased exposure factors to give acceptable images. 57% of patients in the local population now receive much lower radiation doses, whereas 13% require higher doses (but now yield acceptable images). Conclusion: The implementation of size-based exposure protocols has significantly reduced radiation dose to the majority of patients with no negative impact on image quality. Increased doses are required on the largest patients to give adequate image quality. Advances in knowledge: The development of size-based CBCT protocols that use the planning CT scan (with AEC) to determine which protocol is appropriate ensures adequate image quality whilst minimizing patient radiation dose. PMID:26419892

68Ga-PSMA-11 PET/CT Mapping of Prostate Cancer Biochemical Recurrence After Radical Prostatectomy in 270 Patients with a PSA Level of Less Than 1.0 ng/mL: Impact on Salvage Radiotherapy Planning.

PubMed

Calais, Jeremie; Czernin, Johannes; Cao, Minsong; Kishan, Amar U; Hegde, John V; Shaverdian, Narek; Sandler, Kiri; Chu, Fang-I; King, Chris R; Steinberg, Michael L; Rauscher, Isabel; Schmidt-Hegemann, Nina-Sophie; Poeppel, Thorsten; Hetkamp, Philipp; Ceci, Francesco; Herrmann, Ken; Fendler, Wolfgang P; Eiber, Matthias; Nickols, Nicholas G

2018-02-01

Target volume delineations for prostate cancer (PCa) salvage radiotherapy (SRT) after radical prostatectomy are usually drawn in the absence of visibly recurrent disease. 68 Ga-labeled prostate-specific membrane antigen (PSMA-11) PET/CT detects recurrent PCa with sensitivity superior to standard-of-care imaging at serum prostate-specific antigen (PSA) values low enough to affect target volume delineations for routine SRT. Our objective was to map the recurrence pattern of PCa early biochemical recurrence (BCR) after radical prostatectomy with 68 Ga-PSMA-11 PET/CT in patients with serum PSA levels of less than 1 ng/mL, determine how often consensus clinical target volumes (CTVs) based on the Radiation Therapy Oncology Group (RTOG) guidelines cover 68 Ga-PSMA-11 PET/CT-defined disease, and assess the potential impact of 68 Ga-PSMA-11 PET/CT on SRT. Methods: This was a post hoc analysis of an intention-to-treat population of 270 patients who underwent 68 Ga-PSMA-11 PET/CT at 4 institutions for BCR after prostatectomy without prior radiotherapy at a PSA level of less than 1 ng/mL. RTOG consensus CTVs that included both the prostate bed and the pelvic lymph nodes were contoured on the CT dataset of the PET/CT image by a radiation oncologist masked to the PET component. 68 Ga-PSMA-11 PET/CT images were analyzed by a nuclear medicine physician. 68 Ga-PSMA-11-positive lesions not covered by planning volumes based on the consensus CTVs were considered to have a potential major impact on treatment planning. Results: The median PSA level at the time of 68 Ga-PSMA-11 PET/CT was 0.48 ng/mL (range, 0.03-1 ng/mL). One hundred thirty-two of 270 patients (49%) had a positive 68 Ga-PSMA-11 PET/CT result. Fifty-two of 270 (19%) had at least one PSMA-11-positive lesion not covered by the consensus CTVs. Thirty-three of 270 (12%) had extrapelvic PSMA-11-positive lesions, and 19 of 270 (7%) had PSMA-11-positive lesions within the pelvis but not covered by the consensus CTVs. The 2 most common 68 Ga-PSMA-11-positive lesion locations outside the consensus CTVs were bone (23/52, 44%) and perirectal lymph nodes (16/52, 31%). Conclusion: Post hoc analysis of 68 Ga-PSMA-11 PET/CT implied a major impact on SRT planning in 52 of 270 patients (19%) with PCa early BCR (PSA < 1.0 ng/mL). This finding justifies a randomized imaging trial of SRT with or without 68 Ga-PSMA-11 PET/CT investigating its potential benefit on clinical outcome. © 2018 by the Society of Nuclear Medicine and Molecular Imaging.

SU-E-E-16: The Application of Texture Analysis for Differentiation of Central Cancer From Atelectasis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, M; Fan, T; Duan, J

2015-06-15

Purpose: Prospectively assess the potential utility of texture analysis for differentiation of central cancer from atelectasis. Methods: 0 consecutive central lung cancer patients who were referred for CT imaging and PET-CT were enrolled. Radiotherapy doctor delineate the tumor and atelectasis according to the fusion imaging based on CT image and PET-CT image. The texture parameters (such as energy, correlation, sum average, difference average, difference entropy), were obtained respectively to quantitatively discriminate tumor and atelectasis based on gray level co-occurrence matrix (GLCM) Results: The texture analysis results showed that the parameters of correlation and sum average had an obviously statistical significance(P<0.05).more » Conclusion: the results of this study indicate that texture analysis may be useful for the differentiation of central lung cancer and atelectasis.« less

Evaluation of tumor hypoxia prior to radiotherapy in intermediate-risk prostate cancer using 18F-fluoromisonidazole PET/CT: a pilot study.

PubMed

Supiot, Stéphane; Rousseau, Caroline; Dore, Mélanie; Cheze-Le-Rest, Catherine; Kandel-Aznar, Christine; Potiron, Vincent; Guerif, Stéphane; Paris, François; Ferrer, Ludovic; Campion, Loïc; Meingan, Philippe; Delpon, Gregory; Hatt, Mathieu; Visvikis, Dimitris

2018-02-09

Hypoxia is a major factor in prostate cancer aggressiveness and radioresistance. Predicting which patients might be bad candidates for radiotherapy may help better personalize treatment decisions in intermediate-risk prostate cancer patients. We assessed spatial distribution of 18 F-Misonidazole (FMISO) PET/CT uptake in the prostate prior to radiotherapy treatment. Intermediate-risk prostate cancer patients about to receive high-dose (>74 Gy) radiotherapy to the prostate without hormonal treatment were prospectively recruited between 9/2012 and 10/2014. Prior to radiotherapy, all patients underwent a FMISO PET/CT as well as a MRI and 18 F-choline-PET. 18 F-choline and FMISO-positive volumes were semi-automatically determined using the fuzzy locally adaptive Bayesian (FLAB) method. In FMISO-positive patients, a dynamic analysis of early tumor uptake was performed. Group differences were assessed using the Wilcoxon signed rank test. Parameters were correlated using Spearman rank correlation. Of 27 patients (median age 76) recruited to the study, 7 and 9 patients were considered positive at 2.5h and 3.5h FMISO PET/CT respectively. Median SUV max and SUV max tumor to muscle (T/M) ratio were respectively 3.4 and 3.6 at 2.5h, and 3.2 and 4.4 at 3.5h. The median FMISO-positive volume was 1.1 ml. This is the first study regarding hypoxia imaging using FMISO in prostate cancer showing that a small FMISO-positive volume was detected in one third of intermediate-risk prostate cancer patients.

Concept for individualized patient allocation: ReCompare—remote comparison of particle and photon treatment plans

PubMed Central

2014-01-01

Background Identifying those patients who have a higher chance to be cured with fewer side effects by particle beam therapy than by state-of-the-art photon therapy is essential to guarantee a fair and sufficient access to specialized radiotherapy. The individualized identification requires initiatives by particle as well as non-particle radiotherapy centers to form networks, to establish procedures for the decision process, and to implement means for the remote exchange of relevant patient information. In this work, we want to contribute a practical concept that addresses these requirements. Methods We proposed a concept for individualized patient allocation to photon or particle beam therapy at a non-particle radiotherapy institution that bases on remote treatment plan comparison. We translated this concept into the web-based software tool ReCompare (REmote COMparison of PARticlE and photon treatment plans). Results We substantiated the feasibility of the proposed concept by demonstrating remote exchange of treatment plans between radiotherapy institutions and the direct comparison of photon and particle treatment plans in photon treatment planning systems. ReCompare worked with several tested standard treatment planning systems, ensured patient data protection, and integrated in the clinical workflow. Conclusions Our concept supports non-particle radiotherapy institutions with the patient-specific treatment decision on the optimal irradiation modality by providing expertise from a particle therapy center. The software tool ReCompare may help to improve and standardize this personalized treatment decision. It will be available from our website when proton therapy is operational at our facility. PMID:24548333

A scenario for a web-based radiation treatment planning structure: A new tool for quality assurance procedure?

PubMed

Kouloulias, V E; Ntasis, E; Poortmans, Ph; Maniatis, T A; Nikita, K S

2003-01-01

The desire to develop web-based platforms for remote collaboration among physicians and technologists is becoming a great challenge. In this paper we describe a web-based radiotherapy treatment planning (WBRTP) system to facilitate decentralized radiotherapy services by allowing remote treatment planning and quality assurance (QA) of treatment delivery. Significant prerequisites are digital storage of relevant data as well as efficient and reliable telecommunication system between collaborating units. The system of WBRTP includes video conferencing, display of medical images (CT scans, dose distributions etc), replication of selected data from a common database, remote treatment planning, evaluation of treatment technique and follow-up of the treated patients. Moreover the system features real-time remote operations in terms of tele-consulting like target volume delineation performed by a team of experts at different and distant units. An appraisal of its possibilities in quality assurance in radiotherapy is also discussed. As a conclusion, a WBRTP system would not only be a medium for communication between experts in oncology but mainly a tool for improving the QA in radiotherapy.

A longitudinal study on the radiation-induced thyroid gland changes after external beam radiotherapy of nasopharyngeal carcinoma.

PubMed

Lin, Zhixiong; Wu, Vincent Wing-Cheung; Lin, Jing; Feng, Huiting; Chen, Longhua

2011-01-01

Radiation-induced thyroid disorders have been reported in radiotherapy of head and neck cancers. This study evaluated the radiation-induced damages to thyroid gland in patients with nasopharyngeal carcinoma (NPC). Forty-five patients with NPC treated by radiotherapy underwent baseline thyroid hormones (free triiodothyronine, free thyroxine [fT4], and thyrotropin [TSH]) examination and CT scan before radiotherapy. The volume of the thyroid gland was calculated by delineating the structure in the corresponding CT slices using the radiotherapy treatment planning system. The thyroid doses were estimated using the treatment planning system. Subsequent CT scans were conducted at 6, 12, and 18 months after radiotherapy, whereas the hormone levels were assessed at 3, 6, 12, and 18 months after radiotherapy. Trend lines of the volume and hormone level changes against time were plotted. The relationship between the dose and the change of thyroid volume and hormone levels were evaluated using the Pearson correlation test. An average of 20% thyroid volume reduction in the first 6 months and a further 8% shrinkage at 12 months after radiotherapy were observed. The volume reduction was dependent on the mean thyroid doses at 6, 12, and 18 months after radiotherapy (r = -0.399, -0.472, and -0.417, respectively). Serum free triiodothyronine and fT4 levels showed mild changes of <2.5% at 6 months, started to drop by 8.8% and 11.3%, respectively, at 12 months, and became stable at 18 months. The mean serum TSH level increased mildly at 6 months after radiotherapy and more steeply after 18 months. At 18 months after radiotherapy, 12 patients had primary hypothyroidism with an elevated serum TSH, in which 4 of them also presented with low serum fT4. There was a significant difference (p = 0.014) in the mean thyroid doses between patients with hypothyroidism and normal thyroid function. Radiotherapy for patients with NPC caused radiation-induced changes of the thyroid gland. The shrinkage of the gland was greatest in the first 6 months after radiotherapy, whereas the serum fT4 and TSH levels changed at 12 months. Radiation-induced changes were dependent on the mean dose to the gland. Therefore, measures to reduce the thyroid dose in radiotherapy should be considered.

Efficacy of Rasayana Avaleha as adjuvant to radiotherapy and chemotherapy in reducing adverse effects.

PubMed

Vyas, Purvi; Thakar, A B; Baghel, M S; Sisodia, Arvind; Deole, Yogesh

2010-10-01

Cancer is the most dreadful disease affecting mankind. The available treatments such as chemotherapy and radiotherapy have cytotoxic effects, which are hazardous to the normal cells of the patient, causing many unnecessary effects. This further leads to complications of the therapy, impaired health, and deterioration of quality of life, resulting in mandatory stoppage of the treatment. In the present study, the efficacy of an Ayurvedic formulation, Rasayana Avaleha, has been evaluated as an adjuvant medication to modern radiotherapy and chemotherapy. A total of 36 cancer patients were registered in this trial and were divided into two groups, group A and group B. In group A, the patients were treated with radiotherapy and chemotherapy along with adjuvant Rasayana Avaleha (RT + CT + RA), while in group B only radiotherapy and chemotherapy (RT + CT) were given, as the control group. After assessing the results, it was observed that Rasayana Avaleha gave better results in controlling the adverse effect of chemotherapy and radiotherapy in comparison with the control group. Therefore, Rasayana Avaleha has proved to be an effective adjuvant therapy in protecting patients from the adverse effects of chemotherapy and radiotherapy.

SU-F-J-194: Development of Dose-Based Image Guided Proton Therapy Workflow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pham, R; Sun, B; Zhao, T

Purpose: To implement image-guided proton therapy (IGPT) based on daily proton dose distribution. Methods: Unlike x-ray therapy, simple alignment based on anatomy cannot ensure proper dose coverage in proton therapy. Anatomy changes along the beam path may lead to underdosing the target, or overdosing the organ-at-risk (OAR). With an in-room mobile computed tomography (CT) system, we are developing a dose-based IGPT software tool that allows patient positioning and treatment adaption based on daily dose distributions. During an IGPT treatment, daily CT images are acquired in treatment position. After initial positioning based on rigid image registration, proton dose distribution is calculatedmore » on daily CT images. The target and OARs are automatically delineated via deformable image registration. Dose distributions are evaluated to decide if repositioning or plan adaptation is necessary in order to achieve proper coverage of the target and sparing of OARs. Besides online dose-based image guidance, the software tool can also map daily treatment doses to the treatment planning CT images for offline adaptive treatment. Results: An in-room helical CT system is commissioned for IGPT purposes. It produces accurate CT numbers that allow proton dose calculation. GPU-based deformable image registration algorithms are developed and evaluated for automatic ROI-delineation and dose mapping. The online and offline IGPT functionalities are evaluated with daily CT images of the proton patients. Conclusion: The online and offline IGPT software tool may improve the safety and quality of proton treatment by allowing dose-based IGPT and adaptive proton treatments. Research is partially supported by Mevion Medical Systems.« less

Short communication: timeline of radiation-induced kidney function loss after stereotactic ablative body radiotherapy of renal cell carcinoma as evaluated by serial (99m)Tc-DMSA SPECT/CT.

PubMed

Jackson, Price; Foroudi, Farshad; Pham, Daniel; Hofman, Michael S; Hardcastle, Nicholas; Callahan, Jason; Kron, Tomas; Siva, Shankar

2014-11-26

Stereotactic ablative body radiotherapy (SABR) has been proposed as a definitive treatment for patients with inoperable primary renal cell carcinoma. However, there is little documentation detailing the radiobiological effects of hypofractionated radiation on healthy renal tissue. In this study we describe a methodology for assessment of regional change in renal function in response to single fraction SABR of 26 Gy. In a patient with a solitary kidney, detailed follow-up of kidney function post-treatment was determined through 3-dimensional SPECT/CT imaging and (51)Cr-EDTA measurements. Based on measurements of glomerular filtration rate, renal function declined rapidly by 34% at 3 months, plateaued at 43% loss at 12 months, with minimal further decrease to 49% of baseline by 18 months. The pattern of renal functional change in (99m)Tc-DMSA uptake on SPECT/CT imaging correlates with dose delivered. This study demonstrates a dose effect relationship of SABR with loss of kidney function.

A Practical Cone-beam CT Scatter Correction Method with Optimized Monte Carlo Simulations for Image-Guided Radiation Therapy

PubMed Central

Xu, Yuan; Bai, Ti; Yan, Hao; Ouyang, Luo; Pompos, Arnold; Wang, Jing; Zhou, Linghong; Jiang, Steve B.; Jia, Xun

2015-01-01

Cone-beam CT (CBCT) has become the standard image guidance tool for patient setup in image-guided radiation therapy. However, due to its large illumination field, scattered photons severely degrade its image quality. While kernel-based scatter correction methods have been used routinely in the clinic, it is still desirable to develop Monte Carlo (MC) simulation-based methods due to their accuracy. However, the high computational burden of the MC method has prevented routine clinical application. This paper reports our recent development of a practical method of MC-based scatter estimation and removal for CBCT. In contrast with conventional MC approaches that estimate scatter signals using a scatter-contaminated CBCT image, our method used a planning CT image for MC simulation, which has the advantages of accurate image intensity and absence of image truncation. In our method, the planning CT was first rigidly registered with the CBCT. Scatter signals were then estimated via MC simulation. After scatter signals were removed from the raw CBCT projections, a corrected CBCT image was reconstructed. The entire workflow was implemented on a GPU platform for high computational efficiency. Strategies such as projection denoising, CT image downsampling, and interpolation along the angular direction were employed to further enhance the calculation speed. We studied the impact of key parameters in the workflow on the resulting accuracy and efficiency, based on which the optimal parameter values were determined. Our method was evaluated in numerical simulation, phantom, and real patient cases. In the simulation cases, our method reduced mean HU errors from 44 HU to 3 HU and from 78 HU to 9 HU in the full-fan and the half-fan cases, respectively. In both the phantom and the patient cases, image artifacts caused by scatter, such as ring artifacts around the bowtie area, were reduced. With all the techniques employed, we achieved computation time of less than 30 sec including the time for both the scatter estimation and CBCT reconstruction steps. The efficacy of our method and its high computational efficiency make our method attractive for clinical use. PMID:25860299

Magnetic Resonance Lymphography-Guided Selective High-Dose Lymph Node Irradiation in Prostate Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meijer, Hanneke J.M., E-mail: H.Meijer@rther.umcn.nl; Debats, Oscar A.; Kunze-Busch, Martina

2012-01-01

Purpose: To demonstrate the feasibility of magnetic resonance lymphography (MRL) -guided delineation of a boost volume and an elective target volume for pelvic lymph node irradiation in patients with prostate cancer. The feasibility of irradiating these volumes with a high-dose boost to the MRL-positive lymph nodes in conjunction with irradiation of the prostate using intensity-modulated radiotherapy (IMRT) was also investigated. Methods and Materials: In 4 prostate cancer patients with a high risk of lymph node involvement but no enlarged lymph nodes on CT and/or MRI, MRL detected pathological lymph nodes in the pelvis. These lymph nodes were identified and delineatedmore » on a radiotherapy planning CT to create a boost volume. Based on the location of the MRL-positive lymph nodes, the standard elective pelvic target volume was individualized. An IMRT plan with a simultaneous integrated boost (SIB) was created with dose prescriptions of 42 Gy to the pelvic target volume, a boost to 60 Gy to the MRL-positive lymph nodes, and 72 Gy to the prostate. Results: All MRL-positive lymph nodes could be identified on the planning CT. This information could be used to delineate a boost volume and to individualize the pelvic target volume for elective irradiation. IMRT planning delivered highly acceptable radiotherapy plans with regard to the prescribed dose levels and the dose to the organs at risk (OARs). Conclusion: MRL can be used to select patients with limited lymph node involvement for pelvic radiotherapy. MRL-guided delineation of a boost volume and an elective pelvic target volume for selective high-dose lymph node irradiation with IMRT is feasible. Whether this approach will result in improved outcome for these patients needs to be investigated in further clinical studies.« less

Streamlining Workflow for Endovascular Mechanical Thrombectomy: Lessons Learned from a Comprehensive Stroke Center.

PubMed

Wang, Hongjin; Thevathasan, Arthur; Dowling, Richard; Bush, Steven; Mitchell, Peter; Yan, Bernard

2017-08-01

Recently, 5 randomized controlled trials confirmed the superiority of endovascular mechanical thrombectomy (EMT) to intravenous thrombolysis in acute ischemic stroke with large-vessel occlusion. The implication is that our health systems would witness an increasing number of patients treated with EMT. However, in-hospital delays, leading to increased time to reperfusion, are associated with poor clinical outcomes. This review outlines the in-hospital workflow of the treatment of acute ischemic stroke at a comprehensive stroke center and the lessons learned in reduction of in-hospital delays. The in-hospital workflow for acute ischemic stroke was described from prehospital notification to femoral arterial puncture in preparation for EMT. Systematic review of literature was also performed with PubMed. The implementation of workflow streamlining could result in reduction of in-hospital time delays for patients who were eligible for EMT. In particular, time-critical measures, including prehospital notification, the transfer of patients from door to computed tomography (CT) room, initiation of intravenous thrombolysis in the CT room, and the mobilization of neurointervention team in parallel with thrombolysis, all contributed to reduction in time delays. We have identified issues resulting in in-hospital time delays and have reported possible solutions to improve workflow efficiencies. We believe that these measures may help stroke centers initiate an EMT service for eligible patients. Copyright © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Feature-based US to CT registration of the aortic root

NASA Astrophysics Data System (ADS)

Lang, Pencilla; Chen, Elvis C. S.; Guiraudon, Gerard M.; Jones, Doug L.; Bainbridge, Daniel; Chu, Michael W.; Drangova, Maria; Hata, Noby; Jain, Ameet; Peters, Terry M.

2011-03-01

A feature-based registration was developed to align biplane and tracked ultrasound images of the aortic root with a preoperative CT volume. In transcatheter aortic valve replacement, a prosthetic valve is inserted into the aortic annulus via a catheter. Poor anatomical visualization of the aortic root region can result in incorrect positioning, leading to significant morbidity and mortality. Registration of pre-operative CT to transesophageal ultrasound and fluoroscopy images is a major step towards providing augmented image guidance for this procedure. The proposed registration approach uses an iterative closest point algorithm to register a surface mesh generated from CT to 3D US points reconstructed from a single biplane US acquisition, or multiple tracked US images. The use of a single simultaneous acquisition biplane image eliminates reconstruction error introduced by cardiac gating and TEE probe tracking, creating potential for real-time intra-operative registration. A simple initialization procedure is used to minimize changes to operating room workflow. The algorithm is tested on images acquired from excised porcine hearts. Results demonstrate a clinically acceptable accuracy of 2.6mm and 5mm for tracked US to CT and biplane US to CT registration respectively.

SU-E-J-224: Multimodality Segmentation of Head and Neck Tumors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aristophanous, M; Yang, J; Beadle, B

2014-06-01

Purpose: Develop an algorithm that is able to automatically segment tumor volume in Head and Neck cancer by integrating information from CT, PET and MR imaging simultaneously. Methods: Twenty three patients that were recruited under an adaptive radiotherapy protocol had MR, CT and PET/CT scans within 2 months prior to start of radiotherapy. The patients had unresectable disease and were treated either with chemoradiotherapy or radiation therapy alone. Using the Velocity software, the PET/CT and MR (T1 weighted+contrast) scans were registered to the planning CT using deformable and rigid registration respectively. The PET and MR images were then resampled accordingmore » to the registration to match the planning CT. The resampled images, together with the planning CT, were fed into a multi-channel segmentation algorithm, which is based on Gaussian mixture models and solved with the expectation-maximization algorithm and Markov random fields. A rectangular region of interest (ROI) was manually placed to identify the tumor area and facilitate the segmentation process. The auto-segmented tumor contours were compared with the gross tumor volume (GTV) manually defined by the physician. The volume difference and Dice similarity coefficient (DSC) between the manual and autosegmented GTV contours were calculated as the quantitative evaluation metrics. Results: The multimodality segmentation algorithm was applied to all 23 patients. The volumes of the auto-segmented GTV ranged from 18.4cc to 32.8cc. The average (range) volume difference between the manual and auto-segmented GTV was −42% (−32.8%–63.8%). The average DSC value was 0.62, ranging from 0.39 to 0.78. Conclusion: An algorithm for the automated definition of tumor volume using multiple imaging modalities simultaneously was successfully developed and implemented for Head and Neck cancer. This development along with more accurate registration algorithms can aid physicians in the efforts to interpret the multitude of imaging information available in radiotherapy today. This project was supported by a grant by Varian Medical Systems.« less

Assessment of Geometrical Accuracy of Multimodal Images Used for Treatment Planning in Stereotactic Radiotherapy and Radiosurgery: CT, MRI and PET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia-Garduno, O. A.; Larraga-Gutierrez, J. M.; Celis, M. A.

2006-09-08

An acrylic phantom was designed and constructed to assess the geometrical accuracy of CT, MRI and PET images for stereotactic radiotherapy (SRT) and radiosurgery (SRS) applications. The phantom was suited for each image modality with a specific tracer and compared with CT images to measure the radial deviation between the reference marks in the phantom. It was found that for MRI the maximum mean deviation is 1.9 {+-} 0.2 mm compared to 2.4 {+-} 0.3 mm reported for PET. These results will be used for margin outlining in SRS and SRT treatment planning.

Target volume definition for 18F-FDG PET-positive lymph nodes in radiotherapy of patients with non-small cell lung cancer.

PubMed

Nestle, Ursula; Schaefer-Schuler, Andrea; Kremp, Stephanie; Groeschel, Andreas; Hellwig, Dirk; Rübe, Christian; Kirsch, Carl-Martin

2007-04-01

FDG PET is increasingly used in radiotherapy planning. Recently, we demonstrated substantial differences in target volumes when applying different methods of FDG-based contouring in primary lung tumours (Nestle et al., J Nucl Med 2005;46:1342-8). This paper focusses on FDG-positive mediastinal lymph nodes (LN(PET)). In our institution, 51 NSCLC patients who were candidates for radiotherapy prospectively underwent staging FDG PET followed by a thoracic PET scan in the treatment position and a planning CT. Eleven of them had 32 distinguishable non-confluent mediastinal or hilar nodal FDG accumulations (LN(PET)). For these, sets of gross tumour volumes (GTVs) were generated at both acquisition times by four different PET-based contouring methods (visual: GTV(vis); 40% SUVmax: GTV40; SUV=2.5: GTV2.5; target/background (T/B) algorithm: GTV(bg)). All differences concerning GTV sizes were within the range of the resolution of the PET system. The detectability and technical delineability of the GTVs were significantly better in the late scans (e.g. p = 0.02 for diagnostic application of SUVmax = 2.5; p = 0.0001 for technical delineability by GTV2.5; p = 0.003 by GTV40), favouring the GTV(bg) method owing to satisfactory overall applicability and independence of GTVs from acquisition time. Compared with CT, the majority of PET-based GTVs were larger, probably owing to resolution effects, with a possible influence of lesion movements. For nodal GTVs, different methods of contouring did not lead to clinically relevant differences in volumes. However, there were significant differences in technical delineability, especially after early acquisition. Overall, our data favour a late acquisition of FDG PET scans for radiotherapy planning, and the use of a T/B algorithm for GTV contouring.

Automatic segmentation of the clinical target volume and organs at risk in the planning CT for rectal cancer using deep dilated convolutional neural networks.

PubMed

Men, Kuo; Dai, Jianrong; Li, Yexiong

2017-12-01

Delineation of the clinical target volume (CTV) and organs at risk (OARs) is very important for radiotherapy but is time-consuming and prone to inter-observer variation. Here, we proposed a novel deep dilated convolutional neural network (DDCNN)-based method for fast and consistent auto-segmentation of these structures. Our DDCNN method was an end-to-end architecture enabling fast training and testing. Specifically, it employed a novel multiple-scale convolutional architecture to extract multiple-scale context features in the early layers, which contain the original information on fine texture and boundaries and which are very useful for accurate auto-segmentation. In addition, it enlarged the receptive fields of dilated convolutions at the end of networks to capture complementary context features. Then, it replaced the fully connected layers with fully convolutional layers to achieve pixel-wise segmentation. We used data from 278 patients with rectal cancer for evaluation. The CTV and OARs were delineated and validated by senior radiation oncologists in the planning computed tomography (CT) images. A total of 218 patients chosen randomly were used for training, and the remaining 60 for validation. The Dice similarity coefficient (DSC) was used to measure segmentation accuracy. Performance was evaluated on segmentation of the CTV and OARs. In addition, the performance of DDCNN was compared with that of U-Net. The proposed DDCNN method outperformed the U-Net for all segmentations, and the average DSC value of DDCNN was 3.8% higher than that of U-Net. Mean DSC values of DDCNN were 87.7% for the CTV, 93.4% for the bladder, 92.1% for the left femoral head, 92.3% for the right femoral head, 65.3% for the intestine, and 61.8% for the colon. The test time was 45 s per patient for segmentation of all the CTV, bladder, left and right femoral heads, colon, and intestine. We also assessed our approaches and results with those in the literature: our system showed superior performance and faster speed. These data suggest that DDCNN can be used to segment the CTV and OARs accurately and efficiently. It was invariant to the body size, body shape, and age of the patients. DDCNN could improve the consistency of contouring and streamline radiotherapy workflows. © 2017 American Association of Physicists in Medicine.

SU-E-J-187: Individually Optimized Contrast-Enhancement 4D-CT for Pancreatic Adenocarcinoma in Radiotherapy Simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xue, M; Patel, K; Regine, W

2014-06-01

Purpose: To study the feasibility of individually optimized contrastenhancement (CE) 4D-CT for pancreatic adenocarcinoma (PDA) in radiotherapy simulation. To evaluate the image quality and contrast enhancement of tumor in the CE 4D-CT, compared to the clinical standard of CE 3D-CT and 4D-CT. Methods: In this IRB-approved study, each of the 7 PDA patients enrolled underwent 3 CT scans: a free-breathing 3D-CT with contrast (CE 3D-CT) followed by a 4D-CT without contrast (4D-CT) in the first study session, and a 4D-CT with individually synchronized contrast injection (CE 4D-CT) in the second study session. In CE 4D-CT, the time of full contrastmore » injection was determined based on the time of peak enhancement for the test injection, injection rate, table speed, and longitudinal location and span of the pancreatic region. Physicians contoured both the tumor (T) and the normal pancreatic parenchyma (P) on the three CTs (end-of-exhalation for 4D-CT). The contrast between the tumor and normal pancreatic tissue was computed as the difference of the mean enhancement level of three 1 cm3 regions of interests in T and P, respectively. Wilcoxon rank sum test was used to statistically compare the scores and contrasts. Results: In qualitative evaluations, both CE 3D-CT and CE 4D-CT scored significantly better than 4D-CT (4.0 and 3.6 vs. 2.6). There was no significant difference between CE 3D-CT and CE 4D-CT. In quantitative evaluations, the contrasts between the tumor and the normal pancreatic parenchyma were 0.6±23.4, −2.1±8.0, and −19.6±28.8 HU, in CE 3D-CT, 4D-CT, and CE 4D-CT, respectively. Although not statistically significant, CE 4D-CT achieved better contrast enhancement between the tumor and the normal pancreatic parenchyma than both CE 3D-CT and 4DCT. Conclusion: CE 4D-CT achieved equivalent image quality and better contrast enhancement between tumor and normal pancreatic parenchyma than the clinical standard of CE 3D-CT and 4D-CT. This study was supported in part by Philips Healthcare.« less

Collision prediction software for radiotherapy treatments.

PubMed

Padilla, Laura; Pearson, Erik A; Pelizzari, Charles A

2015-11-01

This work presents a method of collision predictions for external beam radiotherapy using surface imaging. The present methodology focuses on collision prediction during treatment simulation to evaluate the clearance of a patient's treatment position and allow for its modification if necessary. A Kinect camera (Microsoft, Redmond, WA) is used to scan the patient and immobilization devices in the treatment position at the simulator. The surface is reconstructed using the skanect software (Occipital, Inc., San Francisco, CA). The treatment isocenter is marked using simulated orthogonal lasers projected on the surface scan. The point cloud of this surface is then shifted to isocenter and converted from Cartesian to cylindrical coordinates. A slab models the treatment couch. A cylinder with a radius equal to the normal distance from isocenter to the collimator plate, and a height defined by the collimator diameter is used to estimate collisions. Points within the cylinder clear through a full gantry rotation with the treatment couch at 0°, while points outside of it collide. The angles of collision are reported. This methodology was experimentally verified using a mannequin positioned in an alpha cradle with both arms up. A planning CT scan of the mannequin was performed, two isocenters were marked in pinnacle, and this information was exported to AlignRT (VisionRT, London, UK)--a surface imaging system for patient positioning. This was used to ensure accurate positioning of the mannequin in the treatment room, when available. Collision calculations were performed for the two treatment isocenters and the results compared to the collisions detected the room. The accuracy of the Kinect-Skanect surface was evaluated by comparing it to the external surface of the planning CT scan. Experimental verification results showed that the predicted angles of collision matched those recorded in the room within 0.5°, in most cases (largest deviation -1.2°). The accuracy study for the Kinect-Skanect surface showed an average discrepancy between the CT external contour and the surface scan of 2.2 mm. This methodology provides fast and reliable collision predictions using surface imaging. The use of the Kinect-Skanect system allows for a comprehensive modeling of the patient topography including all the relevant anatomy and immobilization devices that may lead to collisions. The use of this tool at the treatment simulation stage may allow therapists to evaluate the clearance of a patient's treatment position and optimize it before the planning CT scan is performed. This can allow for safer treatments for the patients due to better collision predictions and improved clinical workflow by minimizing replanning and resimulations due to unforeseen clearance issues.

WE-AB-207A-07: A Planning CT-Guided Scatter Artifact Correction Method for CBCT Images

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, X; Liu, T; Dong, X

Purpose: Cone beam computed tomography (CBCT) imaging is on increasing demand for high-performance image-guided radiotherapy such as online tumor delineation and dose calculation. However, the current CBCT imaging has severe scatter artifacts and its current clinical application is therefore limited to patient setup based mainly on the bony structures. This study’s purpose is to develop a CBCT artifact correction method. Methods: The proposed scatter correction method utilizes the planning CT to improve CBCT image quality. First, an image registration is used to match the planning CT with the CBCT to reduce the geometry difference between the two images. Then, themore » planning CT-based prior information is entered into the Bayesian deconvolution framework to iteratively perform a scatter artifact correction for the CBCT mages. This technique was evaluated using Catphan phantoms with multiple inserts. Contrast-to-noise ratios (CNR) and signal-to-noise ratios (SNR), and the image spatial nonuniformity (ISN) in selected volume of interests (VOIs) were calculated to assess the proposed correction method. Results: Post scatter correction, the CNR increased by a factor of 1.96, 3.22, 3.20, 3.46, 3.44, 1.97 and 1.65, and the SNR increased by a factor 1.05, 2.09, 1.71, 3.95, 2.52, 1.54 and 1.84 for the Air, PMP, LDPE, Polystryrene, Acrylic, Delrin and Teflon inserts, respectively. The ISN decreased from 21.1% to 4.7% in the corrected images. All values of CNR, SNR and ISN in the corrected CBCT image were much closer to those in the planning CT images. The results demonstrated that the proposed method reduces the relevant artifacts and recovers CT numbers. Conclusion: We have developed a novel CBCT artifact correction method based on CT image, and demonstrated that the proposed CT-guided correction method could significantly reduce scatter artifacts and improve the image quality. This method has great potential to correct CBCT images allowing its use in adaptive radiotherapy.« less

Cone Beam CT Imaging Analysis of Interfractional Variations in Bladder Volume and Position During Radiotherapy for Bladder Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yee, Don, E-mail: dony@ualberta.c; Parliament, Matthew; Rathee, Satyapal

2010-03-15

Purpose: To quantify daily bladder size and position variations during bladder cancer radiotherapy. Methods and Materials: Ten bladder cancer patients underwent daily cone beam CT (CBCT) imaging of the bladder during radiotherapy. Bladder and planning target volumes (bladder/PTV) from CBCT and planning CT scans were compared with respect to bladder center-of-mass shifts in the x (lateral), y (anterior-posterior), and z (superior-inferior) coordinates, bladder/PTV size, bladder/PTV margin positions, overlapping areas, and mutually exclusive regions. Results: A total of 262 CBCT images were obtained from 10 bladder cancer patients. Bladder center of mass shifted most in the y coordinate (mean, -0.32 cm).more » The anterior bladder wall shifted the most (mean, -0.58 cm). Mean ratios of CBCT-derived bladder and PTV volumes to planning CT-derived counterparts were 0.83 and 0.88. The mean CBCT-derived bladder volume (+- standard deviation [SD]) outside the planning CT counterpart was 29.24 cm{sup 3} (SD, 29.71 cm{sup 3}). The mean planning CT-derived bladder volume outside the CBCT counterpart was 47.74 cm{sup 3} (SD, 21.64 cm{sup 3}). The mean CBCT PTV outside the planning CT-derived PTV was 47.35 cm{sup 3} (SD, 36.51 cm{sup 3}). The mean planning CT-derived PTV outside the CBCT-derived PTV was 93.16 cm{sup 3} (SD, 50.21). The mean CBCT-derived bladder volume outside the planning PTV was 2.41 cm{sup 3} (SD, 3.97 cm{sup 3}). CBCT bladder/ PTV volumes significantly differed from planning CT counterparts (p = 0.047). Conclusions: Significant variations in bladder and PTV volume and position occurred in patients in this trial.« less

Microvascular transplants in head and neck reconstruction: 3D evaluation of volume loss.

PubMed

Bittermann, Gido; Thönissen, Philipp; Poxleitner, Philipp; Zimmerer, Ruediger; Vach, Kirstin; Metzger, Marc C

2015-10-01

Despite oversized latissimus dorsi free flap reconstruction in the head and neck area, esthetic and functional problems continue to exist due to the well-known occurrence of transplant shrinkage. The purpose of this study was to acquire an estimation of the volume and time of the shrinkage process. The assessment of volume loss was performed using a 3D evaluation of two postoperative CT scans. A retrospective review was conducted on all latissimus dorsi free flap reconstructions performed between 2004 and 2013. Inclusion criteria for the assessment were: resection of an oral carcinoma and microsurgical defect coverage with latissimus dorsi free flap; a first postoperative CT (CT1) performed between 3 weeks and a maximum of 3 months after reconstruction surgery; and an additional CT scan (CT2) performed at least one year postoperatively. The exclusion criterion was surgical intervention in the local area between the acquisition of CT1 and CT2. The effect of adjuvant radiation therapy was considered. Volume determination of the transplant was carried out in CT1 and CT2 by manual segmentation of the graft. Fifteen patients were recruited. 3D evaluation showed an average volume loss of 34.4%. In the consideration of postoperative radiotherapy the volume reduction was 39.2% in patients with radiotherapy and 31.3% in patients without radiotherapy. The reconstruction flap volume required for overcorrection of the surgical defect was investigated. This study indicates that a volume loss of more than 30% could be expected one or more years after latissimus dorsi free flap reconstruction. Clinical trial number DRKS00007534. Copyright © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Initial experience of using an iron-containing fiducial marker for radiotherapy of prostate cancer: Advantages in the visualization of markers in Computed Tomography and Magnetic Resonance Imaging

NASA Astrophysics Data System (ADS)

Tanaka, Osamu; Iida, Takayoshi; Komeda, Hisao; Tamaki, Masayoshi; Seike, Kensaku; Kato, Daiki; Yokoyama, Takamasa; Hirose, Shigeki; Kawaguchi, Daisuke

2016-12-01

Visualization of markers is critical for imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI). However, the size of the marker varies according to the imaging technique. While a large-sized marker is more useful for visualization in MRI, it results in artifacts on CT and causes substantial pain on administration. In contrast, a small-sized marker reduces the artifacts on CT but hampers MRI detection. Herein, we report a new ironcontaining marker and compare its utility with that of non-iron-containing markers. Five patients underwent CT/MRI fusion-based intensity-modulated radiotherapy, and the markers were placed by urologists. A Gold Anchor™ (GA; diameter, 0.28 mm; length, 10 mm) was placed using a 22G needle on the right side of the prostate. A VISICOIL™ (VIS; diameter, 0.35 mm; length, 10 mm) was placed using a 19G needle on the left side. MRI was performed using T2*-weighted imaging. Three observers evaluated and scored the visual qualities of the acquired images. The mean score of visualization was almost identical between the GA and VIS in radiography and cone-beam CT (Novalis Tx). The artifacts in planning CT were slightly larger using the GA than using the VIS. The visualization of the marker on MRI using the GA was superior to that using the VIS. In conclusion, the visualization quality of radiography, conebeam CT, and planning CT was roughly equal between the GA and VIS. However, the GA was more strongly visualized than was the VIS on MRI due to iron containing.

Influence of radiation therapy on the lung-tissue in breast cancer patients: CT-assessed density changes and associated symptoms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rotstein, S.; Lax, I.; Svane, G.

1990-01-01

The relative electron density of lung tissue was measured from computer tomography (CT) slices in 33 breast cancer patients treated by various techniques of adjuvant radiotherapy. The measurements were made before radiotherapy, 3 months and 9 months after completion of radiation therapy. The changes in lung densities at 3 months and 9 months were compared to radiation induced radiological (CT) findings. In addition, subjective symptoms such as cough and dyspnoea were assessed before and after radiotherapy. It was observed that the mean of the relative electron density of lung tissue varied from 0.25 when the whole lung was considered tomore » 0.17 when only the anterior lateral quarter of the lung was taken into account. In patients with positive radiological (CT) findings the mean lung density of the anterior lateral quarter increased 2.1 times 3 months after radiotherapy and was still increased 1.6 times 6 months later. For those patients without findings, in the CT pictures the corresponding values were 1.2 and 1.1, respectively. The standard deviation of the pixel values within the anterior lateral quarter of the lung increased 3.8 times and 3.2 times at 3 months and 9 months, respectively, in the former group, as opposed to 1.2 and 1.1 in the latter group. Thirteen patients had an increase in either cough or dyspnoea as observed 3 months after completion of radiotherapy. In eleven patients these symptoms persisted 6 months later. No significant correlation was found between radiological findings and subjective symptoms. However, when three different treatment techniques were compared among 29 patients the highest rate of radiological findings was observed in patients in which the largest lung volumes received the target dose. A tendency towards an increased rate of subjective symptoms was also found in this group.« less

Effect of increasing radiation dose on pathologic complete response in rectal cancer patients treated with neoadjuvant chemoradiation therapy.

PubMed

Hall, Matthew D; Schultheiss, Timothy E; Smith, David D; Fakih, Marwan G; Wong, Jeffrey Y C; Chen, Yi-Jen

2016-12-01

Neoadjuvant chemoradiation therapy (CRT) increases pathological complete response (pCR) rates compared to radiotherapy alone in patients with stage II-III rectal cancer. Limited evidence addresses whether radiotherapy dose escalation further improves pCR rates. Our purpose is to measure the effects of radiotherapy dose and other factors on post-therapy pathologic tumor (ypT) and nodal stage in rectal cancer patients treated with neoadjuvant CRT followed by mesorectal excision. A non-randomized comparative effectiveness analysis was performed of rectal cancer patients treated in 2000-2013 from the National Oncology Data Alliance™ (NODA), a pooled database of cancer registries from >150 US hospitals. The NODA contains the same data submitted to state cancer registries and SEER combined with validated radiotherapy and chemotherapy records. Eligible patients were treated with neoadjuvant CRT followed by proctectomy and had complete data on treatment start dates, radiotherapy dose, clinical tumor (cT) and ypT stage, and number of positive nodes at surgery (n = 3298 patients). Multivariable logistic regression was used to assess the predictive value of independent variables on achieving a pCR. On multivariable regression, radiotherapy dose, cT stage, and time interval between CRT and surgery were significant predictors of achieving a pCR. After adjusting for the effect of other variates, patients treated with higher radiotherapy doses were also more likely to have negative nodes at surgery and be downstaged from cT3-T4 and/or node positive disease to ypT0-T2N0 after neoadjuvant CRT. Our study suggests that increasing dose significantly improved pCR rates and downstaging in rectal cancer patients treated with neoadjuvant CRT followed by surgery.

Analysis of FET-PET imaging for target volume definition in patients with gliomas treated with conformal radiotherapy.

PubMed

Rieken, Stefan; Habermehl, Daniel; Giesel, Frederik L; Hoffmann, Christoph; Burger, Ute; Rief, Harald; Welzel, Thomas; Haberkorn, Uwe; Debus, Jürgen; Combs, Stephanie E

2013-12-01

Modern radiotherapy (RT) techniques such as stereotactic RT, intensity-modulated RT, or particle irradiation allow local dose escalation with simultaneous sparing of critical organs. Several trials are currently investigating their benefit in glioma reirradiation and boost irradiation. Target volume definition is of critical importance especially when steep dose gradient techniques are employed. In this manuscript we investigate the impact of O-(2-(F-18)fluoroethyl)-l-tyrosine-positron emission tomography/computer tomography (FET-PET/CT) on target volume definition in low and high grade glioma patients undergoing either first or re-irradiation with particles. We investigated volumetric size and uniformity of magnetic resonance imaging (MRI)- vs. FET-PET/CT-derived gross tumor volumes (GTVs) and planning target volumes (PTVs) of 41 glioma patients. Clinical cases are presented to demonstrate potential benefits of integrating FET-PET/CT-planning into daily routine. Integrating FET-uptake into the delineation of GTVs yields larger volumes. Combined modality-derived PTVs are significantly enlarged in high grade glioma patients and in case of primary RT. The congruence of MRI and FET signals for the identification of glioma GTVs is poor with mean uniformity indices of 0.39. MRI-based PTVs miss 17% of FET-PET/CT-based GTVs. Non significant alterations were detected in low grade glioma patients and in those undergoing reirradiation. Target volume definition for malignant gliomas during initial RT may yield significantly differing results depending upon the imaging modality, which the contouring process is based upon. The integration of both MRI and FET-PET/CT may help to improve GTV coverage by avoiding larger incongruences between physical and biological imaging techniques. In low grade gliomas and in cases of reirradiation, more studies are needed in order to investigate a potential benefit of FET-PET/CT for planning of RT. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Utilization of PET-CT in target volume delineation for three-dimensional conformal radiotherapy in patients with non-small cell lung cancer and atelectasis.

PubMed

Yin, Li-Jie; Yu, Xiao-Bin; Ren, Yan-Gang; Gu, Guang-Hai; Ding, Tian-Gui; Lu, Zhi

2013-03-18

To investigate the utilization of PET-CT in target volume delineation for three-dimensional conformal radiotherapy in patients with non-small cell lung cancer (NSCLC) and atelectasis. Thirty NSCLC patients who underwent radical radiotherapy from August 2010 to March 2012 were included in this study. All patients were pathologically confirmed to have atelectasis by imaging examination. PET-CT scanning was performed in these patients. According to the PET-CT scan results, the gross tumor volume (GTV) and organs at risk (OARs, including the lungs, heart, esophagus and spinal cord) were delineated separately both on CT and PET-CT images. The clinical target volume (CTV) was defined as the GTV plus a margin of 6-8 mm, and the planning target volume (PTV) as the GTV plus a margin of 10-15mm. An experienced physician was responsible for designing treatment plans PlanCT and PlanPET-CT on CT image sets. 95% of the PTV was encompassed by the 90% isodose curve, and the two treatment plans kept the same beam direction, beam number, gantry angle, and position of the multi-leaf collimator as much as possible. The GTV was compared using a target delineation system, and doses distributions to OARs were compared on the basis of dose-volume histogram (DVH) parameters. The GTVCT and GTVPET-CT had varying degrees of change in all 30 patients, and the changes in the GTVCT and GTVPET-CT exceeded 25% in 12 (40%) patients. The GTVPET-CT decreased in varying degrees compared to the GTVCT in 22 patients. Their median GTVPET-CT and median GTVPET-CT were 111.4 cm3 (range, 37.8 cm3-188.7 cm3) and 155.1 cm3 (range, 76.2 cm3-301.0 cm3), respectively, and the former was 43.7 cm3 (28.2%) less than the latter. The GTVPET-CT increased in varying degrees compared to the GTVCT in 8 patients. Their median GTVPET-CT and median GTVPET-CT were 144.7 cm3 (range, 125.4 cm3-178.7 cm3) and 125.8 cm3 (range, 105.6 cm3-153.5 cm3), respectively, and the former was 18.9 cm3 (15.0%) greater than the latter. Compared to PlanCT parameters, PlanPET-CT parameters showed varying degrees of changes. The changes in lung V20, V30, esophageal V50 and V55 were statistically significant (Ps< 0.05 for all), while the differences in mean lung dose, lung V5, V10, V15, heart V30, mean esophageal dose, esophagus Dmax, and spinal cord Dmax were not significant (Ps> 0.05 for all). PET-CT allows a better distinction between the collapsed lung tissue and tumor tissue, improving the accuracy of radiotherapy target delineation, and reducing radiation damage to the surrounding OARs in NSCLC patients with atelectasis.

Exclusive Alternating Chemotherapy and Radiotherapy in Nonmetastatic Inflammatory Breast Cancer: 20 Years of Follow-Up

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bourgier, Celine, E-mail: bourgier@igr.fr; Pessoa, Eduardo Lima; Dunant, Ariane

2012-02-01

Background: Locoregional treatment of inflammatory breast cancer (IBC) is crucial because local relapses may be highly symptomatic and are commonly associated with distant metastasis. With a median follow-up of 20 years, we report here the long-term results of a monocentric clinical trial combining primary chemotherapy (CT) with a schedule of anthracycline-based CT and an alternating split-course of radiotherapy (RT Asterisk-Operator CT) without mastectomy. Methods and Materials: From September 1983 to December 1989, 124 women with nonmetastatic IBC (T4d M0) were treated with three cycles of primary AVCMF chemotherapy (anthracycline, vincristine, cyclophosphamide, methotrexate, and 5-fluorouracil) and then an alternating RT Asterisk-Operatormore » CT schedule followed by three cycles of FAC. Hormonal therapy was systematically administered: ovarian irradiation (12 Gy in four fractions) or tamoxifen 20 mg daily. Results: Local control was achieved in 82% of patients. The 10- and 20-year local relapse rates were 26% and 33%, respectively, but only 10% of locally controlled cases were not associated with concurrent distant metastasis. The 10- and 20-year overall survival rates were 39% and 19%, respectively. Severe fibrosis occurred in 54% of patients, grade 3 brachial plexus neuropathy in 4%, grade 2 pneumonitis in 9%. Grade 1, 2 and 3 cardiac toxicity was observed in 3.8%, 3.8% and 1.2% of cases respectively. Conclusions: This combined regimen allowed good long-term local control without surgery. Survival rates were similar to those obtained with conventional regimens (primary chemotherapy, total mastectomy, and adjuvant radiotherapy). Since IBC continues to be an entity with a dismal prognosis, this approach, safely combining preoperative or postoperative radiation therapy and systemic treatments, should be reassessed when suitable targeted agents are available.« less

SU-F-J-34: Automatic Target-Based Patient Positioning Framework for Image-Guided Radiotherapy in Prostate Cancer Treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sasahara, M; Arimura, H; Hirose, T

Purpose: Current image-guided radiotherapy (IGRT) procedure is bonebased patient positioning, followed by subjective manual correction using cone beam computed tomography (CBCT). This procedure might cause the misalignment of the patient positioning. Automatic target-based patient positioning systems achieve the better reproducibility of patient setup. Our aim of this study was to develop an automatic target-based patient positioning framework for IGRT with CBCT images in prostate cancer treatment. Methods: Seventy-three CBCT images of 10 patients and 24 planning CT images with digital imaging and communications in medicine for radiotherapy (DICOM-RT) structures were used for this study. Our proposed framework started from themore » generation of probabilistic atlases of bone and prostate from 24 planning CT images and prostate contours, which were made in the treatment planning. Next, the gray-scale histograms of CBCT values within CTV regions in the planning CT images were obtained as the occurrence probability of the CBCT values. Then, CBCT images were registered to the atlases using a rigid registration with mutual information. Finally, prostate regions were estimated by applying the Bayesian inference to CBCT images with the probabilistic atlases and CBCT value occurrence probability. The proposed framework was evaluated by calculating the Euclidean distance of errors between two centroids of prostate regions determined by our method and ground truths of manual delineations by a radiation oncologist and a medical physicist on CBCT images for 10 patients. Results: The average Euclidean distance between the centroids of extracted prostate regions determined by our proposed method and ground truths was 4.4 mm. The average errors for each direction were 1.8 mm in anteroposterior direction, 0.6 mm in lateral direction and 2.1 mm in craniocaudal direction. Conclusion: Our proposed framework based on probabilistic atlases and Bayesian inference might be feasible to automatically determine prostate regions on CBCT images.« less

Recommendations for the use of radiotherapy in nodal lymphoma.

PubMed

Hoskin, P J; Díez, P; Williams, M; Lucraft, H; Bayne, M

2013-01-01

These guidelines have been developed to define the use of radiotherapy for lymphoma in the current era of combined modality treatment taking into account increasing concern over the late side-effects associated with previous radiotherapy. The role of reduced volume and reduced doses is addressed, integrating modern imaging with three-dimensional planning and advanced techniques of treatment delivery. Both wide-field and involved-field techniques have now been supplanted by the use of defined volumes based on node involvement shown on computed tomography (CT) and positron emission tomography (PET) imaging and applying the International Commission on Radiation Units and Measurements concepts of gross tumour volume (GTV), clinical target volume (CTV) and planning target volume (PTV). The planning of lymphoma patients for radical radiotherapy should now be based upon contrast enhanced 3 mm contiguous CT with three-dimensional definition of volumes using the convention of GTV, CTV and PTV. The involved-site radiotherapy concept defines the CTV based on the PET-defined pre-chemotherapy sites of involvement with an expansion in the cranio-caudal direction of lymphatic spread by 1.5 cm, constrained to tissue planes such as bone, muscle and air cavities. The margin allows for uncertainties in PET resolution, image registration and changes in patient positioning and shape. There is increasing evidence in both Hodgkin and non-Hodgkin lymphoma that traditional doses are higher than necessary for disease control and related to the incidence of late effects. No more than 30 Gy for Hodgkin and aggressive non-Hodgkin lymphoma and 24 Gy for indolent lymphomas is recommended; lower doses of 20 Gy in combination therapy for early-stage low-risk Hodgkin lymphoma may be sufficient. As yet there are no large datasets validating the use of involved-site radiotherapy; these will emerge from the current generation of clinical trials. Radiotherapy remains the most effective single modality in the treatment of lymphoma. A reduction in both treatment volume and overall treatment dose should now be considered to minimise the risks of late sequelae. However, it is important that this is not at the expense of the excellent disease control currently achieved. Copyright © 2012 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Automated ultrafast kilovoltage-megavoltage cone-beam CT for image guided radiotherapy of lung cancer: System description and real-time results.

PubMed

Blessing, Manuel; Arns, Anna; Wertz, Hansjoerg; Stsepankou, Dzmitry; Boda-Heggemann, Judit; Hesser, Juergen; Wenz, Frederik; Lohr, Frank

2018-04-01

To establish a fully automated kV-MV CBCT imaging method on a clinical linear accelerator that allows image acquisition of thoracic targets for patient positioning within one breath-hold (∼15s) under realistic clinical conditions. Our previously developed FPGA-based hardware unit which allows synchronized kV-MV CBCT projection acquisition is connected to a clinical linear accelerator system via a multi-pin switch; i.e. either kV-MV imaging or conventional clinical mode can be selected. An application program was developed to control the relevant linac parameters automatically and to manage the MV detector readout as well as the gantry angle capture for each MV projection. The kV projections are acquired with the conventional CBCT system. GPU-accelerated filtered backprojection is performed separately for both data sets. After appropriate grayscale normalization both modalities are combined and the final kV-MV volume is re-imported in the CBCT system to enable image matching. To demonstrate adequate geometrical accuracy of the novel imaging system the Penta-Guide phantom QA procedure is performed. Furthermore, a human plastinate and different tumor shapes in a thorax phantom are scanned. Diameters of the known tumor shapes are measured in the kV-MV reconstruction. An automated kV-MV CBCT workflow was successfully established in a clinical environment. The overall procedure, from starting the data acquisition until the reconstructed volume is available for registration, requires ∼90s including 17s acquisition time for 100° rotation. It is very simple and allows target positioning in the same way as for conventional CBCT. Registration accuracy of the QA phantom is within ±1mm. The average deviation from the known tumor dimensions measured in the thorax phantom was 0.7mm which corresponds to an improvement of 36% compared to our previous kV-MV imaging system. Due to automation the kV-MV CBCT workflow is speeded up by a factor of >10 compared to the manual approach. Thus, the system allows a simple, fast and reliable imaging procedure and fulfills all requirements to be successfully introduced into the clinical workflow now, enabling single-breath-hold volume imaging. Copyright © 2018. Published by Elsevier GmbH.

Consequences of additional use of PET information for target volume delineation and radiotherapy dose distribution for esophageal cancer.

PubMed

Muijs, Christina T; Schreurs, Liesbeth M; Busz, Dianne M; Beukema, Jannet C; van der Borden, Arnout J; Pruim, Jan; Van der Jagt, Eric J; Plukker, John Th; Langendijk, Johannes A

2009-12-01

To determine the consequences of target volume (TV) modifications, based on the additional use of PET information, on radiation planning, assuming PET/CT-imaging represents the true extent of the tumour. For 21 patients with esophageal cancer, two separate TV's were retrospectively defined based on CT (CT-TV) and co-registered PET/CT images (PET/CT-TV). Two 3D-CRT plans (prescribed dose 50.4 Gy) were constructed to cover the corresponding TV's. Subsequently, these plans were compared for target coverage, normal tissue dose-volume histograms and the corresponding normal tissue complication probability (NTCP) values. The addition of PET led to the modification of CT-TV with at least 10% in 12 of 21 patients (57%) (reduction in 9, enlargement in 3). PET/CT-TV was inadequately covered by the CT-based treatment plan in 8 patients (36%). Treatment plan modifications resulted in significant changes (p<0.05) in dose distributions to heart and lungs. Corresponding changes in NTCP values ranged from -3% to +2% for radiation pneumonitis and from -0.2% to +1.2% for cardiac mortality. This study demonstrated that TV's based on CT might exclude PET-avid disease. Consequences are under dosing and thereby possibly ineffective treatment. Moreover, the addition of PET in radiation planning might result in clinical important changes in NTCP.

Demons deformable registration of CT and cone-beam CT using an iterative intensity matching approach.

PubMed

Nithiananthan, Sajendra; Schafer, Sebastian; Uneri, Ali; Mirota, Daniel J; Stayman, J Webster; Zbijewski, Wojciech; Brock, Kristy K; Daly, Michael J; Chan, Harley; Irish, Jonathan C; Siewerdsen, Jeffrey H

2011-04-01

A method of intensity-based deformable registration of CT and cone-beam CT (CBCT) images is described, in which intensity correction occurs simultaneously within the iterative registration process. The method preserves the speed and simplicity of the popular Demons algorithm while providing robustness and accuracy in the presence of large mismatch between CT and CBCT voxel values ("intensity"). A variant of the Demons algorithm was developed in which an estimate of the relationship between CT and CBCT intensity values for specific materials in the image is computed at each iteration based on the set of currently overlapping voxels. This tissue-specific intensity correction is then used to estimate the registration output for that iteration and the process is repeated. The robustness of the method was tested in CBCT images of a cadaveric head exhibiting a broad range of simulated intensity variations associated with x-ray scatter, object truncation, and/or errors in the reconstruction algorithm. The accuracy of CT-CBCT registration was also measured in six real cases, exhibiting deformations ranging from simple to complex during surgery or radiotherapy guided by a CBCT-capable C-arm or linear accelerator, respectively. The iterative intensity matching approach was robust against all levels of intensity variation examined, including spatially varying errors in voxel value of a factor of 2 or more, as can be encountered in cases of high x-ray scatter. Registration accuracy without intensity matching degraded severely with increasing magnitude of intensity error and introduced image distortion. A single histogram match performed prior to registration alleviated some of these effects but was also prone to image distortion and was quantifiably less robust and accurate than the iterative approach. Within the six case registration accuracy study, iterative intensity matching Demons reduced mean TRE to (2.5 +/- 2.8) mm compared to (3.5 +/- 3.0) mm with rigid registration. A method was developed to iteratively correct CT-CBCT intensity disparity during Demons registration, enabling fast, intensity-based registration in CBCT-guided procedures such as surgery and radiotherapy, in which CBCT voxel values may be inaccurate. Accurate CT-CBCT registration in turn facilitates registration of multimodality preoperative image and planning data to intraoperative CBCT by way of the preoperative CT, thereby linking the intraoperative frame of reference to a wealth of preoperative information that could improve interventional guidance.

[18F]fluoroethylcholine-PET/CT imaging for radiation treatment planning of recurrent and primary prostate cancer with dose escalation to PET/CT-positive lymph nodes.

PubMed

Würschmidt, Florian; Petersen, Cordula; Wahl, Andreas; Dahle, Jörg; Kretschmer, Matthias

2011-05-01

At present there is no consensus on irradiation treatment volumes for intermediate to high-risk primary cancers or recurrent disease. Conventional imaging modalities, such as CT, MRI and transrectal ultrasound, are considered suboptimal for treatment decisions. Choline-PET/CT might be considered as the imaging modality in radiooncology to select and delineate clinical target volumes extending the prostate gland or prostate fossa. In conjunction with intensity modulated radiotherapy (IMRT) and imaged guided radiotherapy (IGRT), it might offer the opportunity of dose escalation to selected sites while avoiding unnecessary irradiation of healthy tissues. Twenty-six patients with primary (n = 7) or recurrent (n = 19) prostate cancer received Choline-PET/CT planned 3D conformal or intensity modulated radiotherapy. The median age of the patients was 65 yrs (range 45 to 78 yrs). PET/CT-scans with F18-fluoroethylcholine (FEC) were performed on a combined PET/CT-scanner equipped for radiation therapy planning. The majority of patients had intermediate to high risk prostate cancer. All patients received 3D conformal or intensity modulated and imaged guided radiotherapy with megavoltage cone beam CT. The median dose to primary tumours was 75.6 Gy and to FEC-positive recurrent lymph nodal sites 66,6 Gy. The median follow-up time was 28.8 months. The mean SUV(max) in primary cancer was 5,97 in the prostate gland and 3,2 in pelvic lymph nodes. Patients with recurrent cancer had a mean SUV(max) of 4,38. Two patients had negative PET/CT scans. At 28 months the overall survival rate is 94%. Biochemical relapse free survival is 83% for primary cancer and 49% for recurrent tumours. Distant disease free survival is 100% and 75% for primary and recurrent cancer, respectively. Acute normal tissue toxicity was mild in 85% and moderate (grade 2) in 15%. No or mild late side effects were observed in the majority of patients (84%). One patient had a severe bladder shrinkage (grade 4) after a previous treatment with TUR of the prostate and seed implantation. FEC-PET/CT planning could be helpful in dose escalation to lymph nodal sites of prostate cancer.

WE-AB-204-03: A Novel 3D Printed Phantom for 4D PET/CT Imaging and SIB Radiotherapy Verification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soultan, D; Murphy, J; Moiseenko, V

Purpose: To construct and test a 3D printed phantom designed to mimic variable PET tracer uptake seen in lung tumor volumes. To assess segmentation accuracy of sub-volumes of the phantom following 4D PET/CT scanning with ideal and patient-specific respiratory motion. To plan, deliver and verify delivery of PET-driven, gated, simultaneous integrated boost (SIB) radiotherapy plans. Methods: A set of phantoms and inserts were designed and manufactured for a realistic representation of lung cancer gated radiotherapy steps from 4D PET/CT scanning to dose delivery. A cylindrical phantom (40x 120 mm) holds inserts for PET/CT scanning. The novel 3D printed insert dedicatedmore » to 4D PET/CT mimics high PET tracer uptake in the core and lower uptake in the periphery. This insert is a variable density porous cylinder (22.12×70 mm), ABS-P430 thermoplastic, 3D printed by uPrint SE Plus with inner void volume (5.5×42 mm). The square pores (1.8×1.8 mm2 each) fill 50% of outer volume, resulting in a 2:1 SUV ratio of PET-tracer in the void volume with respect to porous volume. A matching in size cylindrical phantom is dedicated to validate gated radiotherapy. It contains eight peripheral holes matching the location of the porous part of the 3D printed insert, and one central hole. These holes accommodate adaptors for Farmer-type ion chamber and cells vials. Results: End-to-end test were performed from 4D PET/CT scanning to transferring data to the planning system and target volume delineation. 4D PET/CT scans were acquired of the phantom with different respiratory motion patterns and gating windows. A measured 2:1 18F-FDG SUV ratio between inner void and outer volume matched the 3D printed design. Conclusion: The novel 3D printed phantom mimics variable PET tracer uptake typical of tumors. Obtained 4D PET/CT scans are suitable for segmentation, treatment planning and delivery in SIB gated treatments of NSCLC.« less

SU-E-J-91: Biomechanical Deformable Image Registration of Longitudinal Lung CT Images

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cazoulat, G; Owen, D; Matuszak, M

2015-06-15

Purpose: Spatial correlation of lung tissue across longitudinal images, as the patient responds to treatment, is a critical step in adaptive radiotherapy. The goal of this work is to expand a biomechanical model-based deformable registration algorithm (Morfeus) to achieve accurate registration in the presence of significant anatomical changes. Methods: Four lung cancer patients previously treated with conventionally fractionated radiotherapy that exhibited notable tumor shrinkage during treatment were retrospectively evaluated. Exhale breathhold CT scans were obtained at treatment planning (PCT) and following three weeks (W3CT) of treatment. For each patient, the PCT was registered to the W3CT using Morfeus, a biomechanicalmore » model-based deformable registration algorithm, consisting of boundary conditions on the lungs and incorporating a sliding interface between the lung and chest wall. To model the complex response of the lung, an extension to Morfeus has been developed: (i) The vessel tree was segmented by thresholding a vesselness image based on the Hessian matrix’s eigenvalues and the centerline was extracted; (ii) A 3D shape context method was used to find correspondences between the trees of the two images; (ii) Correspondences were used as additional boundary conditions (Morfeus+vBC). An expert independently identified corresponding landmarks well distributed in the lung to compute Target Registration Errors (TRE). Results: The TRE within 15mm of the tumor boundaries (on average 11 landmarks) is: 6.1±1.8, 4.6±1.1 and 3.8±2.3 mm after rigid registration, Morfeus and Morfeus+vBC, respectively. The TRE in the rest of the lung (on average 13 landmarks) is: 6.4±3.9, 4.7±2.2 and 3.6±1.9 mm, which is on the order of the 2mm isotropic dose grid vector (3.5mm). Conclusion: The addition of boundary conditions on the vessels improved the accuracy in modeling the response of the lung and tumor over the course of radiotherapy. Minimizing and modeling these geometrical uncertainties will enable future plan adaptation strategies. This work was funded in part by NIH 2P01CA059827-16.« less

Magnetic resonance (MR) imaging for tumor staging and definition of tumor volumes on radiation treatment planning in nonsmall cell lung cancer: A prospective radiographic cohort study of single center clinical outcome.

PubMed

Zhao, Dan; Hu, Qiaoqiao; Qi, Liping; Wang, Juan; Wu, Hao; Zhu, Guangying; Yu, Huiming

2017-02-01

We investigate the impact of magnetic resonance (MR) on the staging and radiotherapy planning for patients with nonsmall cell lung cancer (NSCLC).A total of 24 patients with NSCLC underwent MRI, which was fused with radiotherapy planning CT using rigid registration. Gross tumor volume (GTV) was delineated not only according to CT image alone (GTVCT), but also based on both CT and MR image (GTVCT/MR). For each patient, 2 conformal treatment plans were made according to GTVCT and GTVCT/MR, respectively. Dose-volume histograms (DVH) for lesion and normal organs were generated using both GTVCT and GTVCT/MR treatment plans. All patients were irradiated according to GTVCT/MR plan.Median volume of the GTVCT/MR and GTVCT were 105.42 cm and 124.45 cm, respectively, and the mean value of GTVCT/MR was significantly smaller than that of GTVCT (145.71 ± 145.04 vs 174.30 ± 150.34, P < 0.01). Clinical stage was modified in 9 patients (37.5%). The objective response rate (ORR) was 83.3% and the l-year overall survival (OS) was 87.5%.MR is a useful tool in radiotherapy treatment planning for NSCLC, which improves the definition of tumor volume, reduces organs at risk dose and does not increase the local recurrence rate.

Server-based enterprise collaboration software improves safety and quality in high-volume PET/CT practice.

PubMed

McDonald, James E; Kessler, Marcus M; Hightower, Jeremy L; Henry, Susan D; Deloney, Linda A

2013-12-01

With increasing volumes of complex imaging cases and rising economic pressure on physician staffing, timely reporting will become progressively challenging. Current and planned iterations of PACS and electronic medical record systems do not offer workflow management tools to coordinate delivery of imaging interpretations with the needs of the patient and ordering physician. The adoption of a server-based enterprise collaboration software system by our Division of Nuclear Medicine has significantly improved our efficiency and quality of service.

Vertebral Hemangioma Mimicking Bone Metastasis in 68Ga-PSMA Ligand PET/CT.

PubMed

Artigas, Carlos; Otte, François-Xavier; Lemort, Marc; van Velthoven, Roland; Flamen, Patrick

2017-05-01

Ga-PSMA PET/CT was performed in a 68-year-old man to evaluate recurrent prostate cancer due to elevated serum prostate-specific antigen level. Images showed a focal uptake in the prostatic gland, suggesting local relapse, and an intense uptake in the 12th thoracic vertebra, with no morphological abnormalities in CT slices. In order to confirm extraprostatic disease and before radiotherapy planning, a full-spine MRI was performed, resulting with the morphological pattern of a vertebral hemangioma. Hystological analysis confirmed the local relapse in the prostate. No radiotherapy treatment was given to the vertebra, and after 1 year of follow-up without systemic treatment, prostate-specific antigen is still undetectable.

MO-B-BRC-01: Introduction [Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prisciandaro, J.

2016-06-15

Brachytherapy has proven to be an effective treatment option for prostate cancer. Initially, prostate brachytherapy was delivered through permanently implanted low dose rate (LDR) radioactive sources; however, high dose rate (HDR) temporary brachytherapy for prostate cancer is gaining popularity. Needle insertion during prostate brachytherapy is most commonly performed under ultrasound (U/S) guidance; however, treatment planning may be performed utilizing several imaging modalities either in an intra- or post-operative setting. During intra-operative prostate HDR, the needles are imaged during implantation, and planning may be performed in real time. At present, the most common imaging modality utilized for intra-operative prostate HDR ismore » U/S. Alternatively, in the post-operative setting, following needle implantation, patients may be simulated with computed tomography (CT) or magnetic resonance imaging (MRI). Each imaging modality and workflow provides its share of benefits and limitations. Prostate HDR has been adopted in a number of cancer centers across the nation. In this educational session, we will explore the role of U/S, CT, and MRI in HDR prostate brachytherapy. Example workflows and operational details will be shared, and we will discuss how to establish a prostate HDR program in a clinical setting. Learning Objectives: Review prostate HDR techniques based on the imaging modality Discuss the challenges and pitfalls introduced by the three imagebased options for prostate HDR brachytherapy Review the QA process and learn about the development of clinical workflows for these imaging options at different institutions.« less

MO-B-BRC-00: Prostate HDR Treatment Planning - Considering Different Imaging Modalities

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

2016-06-15

Brachytherapy has proven to be an effective treatment option for prostate cancer. Initially, prostate brachytherapy was delivered through permanently implanted low dose rate (LDR) radioactive sources; however, high dose rate (HDR) temporary brachytherapy for prostate cancer is gaining popularity. Needle insertion during prostate brachytherapy is most commonly performed under ultrasound (U/S) guidance; however, treatment planning may be performed utilizing several imaging modalities either in an intra- or post-operative setting. During intra-operative prostate HDR, the needles are imaged during implantation, and planning may be performed in real time. At present, the most common imaging modality utilized for intra-operative prostate HDR ismore » U/S. Alternatively, in the post-operative setting, following needle implantation, patients may be simulated with computed tomography (CT) or magnetic resonance imaging (MRI). Each imaging modality and workflow provides its share of benefits and limitations. Prostate HDR has been adopted in a number of cancer centers across the nation. In this educational session, we will explore the role of U/S, CT, and MRI in HDR prostate brachytherapy. Example workflows and operational details will be shared, and we will discuss how to establish a prostate HDR program in a clinical setting. Learning Objectives: Review prostate HDR techniques based on the imaging modality Discuss the challenges and pitfalls introduced by the three imagebased options for prostate HDR brachytherapy Review the QA process and learn about the development of clinical workflows for these imaging options at different institutions.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joseph, A.; Seuntjens, J.; Parker, W.

We describe development of automated, web-based, electronic health record (EHR) auditing software for use within our paperless radiation oncology clinic. By facilitating access to multiple databases within the clinic, each patient's EHR is audited prior to treatment, regularly during treatment, and post treatment. Anomalies such as missing documentation, non-compliant workflow and treatment parameters that differ significantly from the norm may be monitored, flagged and brought to the attention of clinicians. By determining historical trends using existing patient data and by comparing new patient data with the historical, we expect our software to provide a measurable improvement in the quality ofmore » radiotherapy at our centre.« less

A comparative study of the target volume definition in radiotherapy with «Slow CT Scan» vs. 4D PET/CT Scan in early stages non-small cell lung cancer.

PubMed

Molla, M; Anducas, N; Simó, M; Seoane, A; Ramos, M; Cuberas-Borros, G; Beltran, M; Castell, J; Giralt, J

To evaluate the use of 4D PET/CT to quantify tumor respiratory motion compared to the «Slow»-CT (CTs) in the radiotherapy planning process. A total of 25 patients with inoperable early stage non small cell lung cancer (NSCLC) were included in the study. Each patient was imaged with a CTs (4s/slice) and 4D PET/CT. The adequacy of each technique for respiratory motion capture was evaluated using the volume definition for each of the following: Internal target volume (ITV) 4D and ITVslow in relation with the volume defined by the encompassing volume of 4D PET/CT and CTs (ITVtotal). The maximum distance between the edges of the volume defined by each technique to that of the total volume was measured in orthogonal beam's eye view. The ITV4D showed less differences in relation with the ITVtotal in both the cranio-caudal and the antero-posterior axis compared to the ITVslow. The maximum differences were 0.36mm in 4D PET/CTand 0.57mm in CTs in the antero-posterior axis. 4D PET/CT resulted in the definition of more accurate (ITV4D/ITVtotal 0.78 vs. ITVs/ITVtotal 0.63), and larger ITVs (19.9 cc vs. 16.3 cc) than those obtained with CTs. Planning with 4D PET/CT in comparison with CTs, allows incorporating tumor respiratory motion and improving planning radiotherapy of patients in early stages of lung cancer. Copyright © 2016 Elsevier España, S.L.U. y SEMNIM. All rights reserved.

Evaluation of volume change in rectum and bladder during application of image-guided radiotherapy for prostate carcinoma

NASA Astrophysics Data System (ADS)

Luna, J. A.; Rojas, J. I.

2016-07-01

All prostate cancer patients from Centro Médico Radioterapia Siglo XXI receive Volumetric Modulated Arc Therapy (VMAT). This therapy uses image-guided radiotherapy (IGRT) with the Cone Beam Computed Tomography (CBCT). This study compares the planned dose in the reference CT image against the delivered dose recalculate in the CBCT image. The purpose of this study is to evaluate the anatomic changes and related dosimetric effect based on weekly CBCT directly for patients with prostate cancer undergoing volumetric modulated arc therapy (VMAT) treatment. The collected data were analyzed using one-way ANOVA.

CT-based definition of thoracic lymph node stations: an atlas from the University of Michigan.

PubMed

Chapet, Olivier; Kong, Feng-Ming; Quint, Leslie E; Chang, Andrew C; Ten Haken, Randall K; Eisbruch, Avraham; Hayman, James A

2005-09-01

Accurate delineation of the mediastinal and hilar lymph node regions is essential for a reproducible definition of target volumes used in conformal irradiation of non-small-cell lung cancer. The goal of this work was to generate a consensus to delineate these nodal regions based on definitions from the American Joint Committee on Cancer. A dedicated thoracic radiologist, thoracic surgeon, medical physicist, and three radiation oncologists were gathered to generate a three-dimensional radiologic description for the mediastinal and hilar nodal regions on axial CT scans. This paper proposes an atlas of most of the lymph node stations described by Mountain and Dresler. The CT boundaries of lymph node stations 1-2, 3, 4, 5, 6, 7, 8, 10-11 were defined on axial CT, along with image illustrations. These CT-based illustrative definitions will provide guidelines for clinical practice and studies evaluating incidental radiation in radiotherapy. Studies are ongoing at the University of Michigan to measure quantitatively the incidental nodal radiation received by patients with non-small-cell lung cancer.

SU-E-T-504: Usefulness of CT-MR Fusion in Radiotherapy Planning for Prostate Cancer Patient with Bilateral Hip Replacements

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, R.; Giri, Shankar; VA Medical Center at Jackson, Mississippi

2014-06-01

Purpose: Target localization of prostate for Intensity Modulated Radiation Therapy (IMRT) in patients with bilateral hip replacements is difficult due to artifacts in Computed Tomography (CT) images generated from the prostheses high Z materials. In this study, Magnetic Resonance (MR) images fused with CT images are tested as a solution. Methods: CT images of 2.5 mm slice thickness were acquired on a GE Lightspeed scanner with a flat-topped couch for a prostate cancer patient with bilateral hip replacements. T2 weighted images of 5 mm separation were acquired on a MR Scanner. After the MR-CT registration on a radiotherapy treatment planningmore » system (Eclipse, Varian), the target volumes were defined by the radiation oncologists on MR images and then transferred to CT images for planning and dose calculation. The CT Hounsfield Units (HU) was reassigned to zero (as water) for artifacts. The Varian flat panel treatment couch was modeled for dose calculation accuracy with heterogeneity correction. A Volume Matrix Arc Therapy (VMAT) and a seven-field IMRT plans were generated, each avoiding any beam transversing the prostheses; the two plans were compared. The superior VMAT plan was used for treating the patient. In-vivo dosimetry was performed using MOSFET (Best Canada) placed in a surgical tube inserted into the patient rectum during therapy. The measured dose was compared with planned dose for MOSFET location. Results: The registration of MR-CT images and the agreement of target volumes were confirmed by three physicians. VMAT plan was deemed superior to IMRT based on dose to critical nearby structures and overall conformality of target dosing. In-vivo measured dose compared with calculated dose was -4.5% which was likely due to attenuation of the surgical tube surrounding MOSFET. Conclusion: When artifacts are present on planning CT due to bilateral hip prostheses, MR-CT image fusion is a feasible solution for target delineation.« less

[Image-guided radiotherapy and partial delegation to radiotherapy technicians: Clermont-Ferrand experience].

PubMed

Loos, G; Moreau, J; Miroir, J; Benhaïm, C; Biau, J; Caillé, C; Bellière, A; Lapeyre, M

2013-10-01

The various image-guided radiotherapy techniques raise the question of how to achieve the control of patient positioning before irradiation session and sharing of tasks between radiation oncologists and radiotherapy technicians. We have put in place procedures and operating methods to make a partial delegation of tasks to radiotherapy technicians and secure the process in three situations: control by orthogonal kV imaging (kV-kV) of bony landmarks, control by kV-kV imaging of intraprostatic fiducial goldmarkers and control by cone beam CT (CBCT) imaging for prostate cancer. Significant medical overtime is required to control these three IGRT techniques. Because of their competence in imaging, these daily controls can be delegated to radiotherapy technicians. However, to secure the process, initial training and regular evaluation are essential. The analysis of the comparison of the use of kV/kV on bone structures allowed us to achieve a partial delegation of control to radiotherapy technicians. Controlling the positioning of the prostate through the use and automatic registration of fiducial goldmarkers allows better tracking of the prostate and can be easily delegated to radiotherapy technicians. The analysis of the use of daily cone beam CT for patients treated with intensity modulated irradiation is underway, and a comparison of practices between radiotherapy technicians and radiation oncologists is ongoing to know if a partial delegation of this control is possible. Copyright © 2013. Published by Elsevier SAS.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paliwal, B; Asprey, W; Yan, Y

Purpose: In order to take advantage of the high resolution soft tissue imaging available in MR images, we investigated 3D images obtained with the low field 0.35 T MR in ViewRay to serve as an alternative to CT scans for radiotherapy treatment planning. In these images, normal and target structure delineation can be visualized. Assessment is based upon comparison with the CT images and the ability to produce comparable contours. Methods: Routine radiation oncology CT scans were acquired on five patients. Contours of brain, brainstem, esophagus, heart, lungs, spinal cord, and the external body were drawn. The same five patientsmore » were then scanned on the ViewRay TrueFISP-based imaging pulse sequence. The same organs were selected on the MR images and compared to those from the CT scan. Physical volume and the Dice Similarity Coefficient (DSC) were used to assess the contours from the two systems. Image quality stability was quantitatively ensured throughout the study following the recommendations of the ACR MR accreditation procedure. Results: The highest DSC of 0.985, 0.863, and 0.843 were observed for brain, lungs, and heart respectively. On the other hand, the brainstem, spinal cord, and esophagus had the lowest DSC. Volume agreement was most satisfied for the heart (within 5%) and the brain (within 2%). Contour volume for the brainstem and lung (a widely dynamic organ) varied the most (27% and 19%). Conclusion: The DSC and volume measurements suggest that the results obtained from ViewRay images are quantitatively consistent and comparable to those obtained from CT scans for the brain, heart, and lungs. MR images from ViewRay are well-suited for treatment planning and for adaptive MRI-guided radiotherapy. The physical data from 0.35 T MR imaging is consistent with our geometrical understanding of normal structures.« less

Non-rigid CT/CBCT to CBCT registration for online external beam radiotherapy guidance

NASA Astrophysics Data System (ADS)

Zachiu, Cornel; de Senneville, Baudouin Denis; Tijssen, Rob H. N.; Kotte, Alexis N. T. J.; Houweling, Antonetta C.; Kerkmeijer, Linda G. W.; Lagendijk, Jan J. W.; Moonen, Chrit T. W.; Ries, Mario

2018-01-01

Image-guided external beam radiotherapy (EBRT) allows radiation dose deposition with a high degree of accuracy and precision. Guidance is usually achieved by estimating the displacements, via image registration, between cone beam computed tomography (CBCT) and computed tomography (CT) images acquired at different stages of the therapy. The resulting displacements are then used to reposition the patient such that the location of the tumor at the time of treatment matches its position during planning. Moreover, ongoing research aims to use CBCT-CT image registration for online plan adaptation. However, CBCT images are usually acquired using a small number of x-ray projections and/or low beam intensities. This often leads to the images being subject to low contrast, low signal-to-noise ratio and artifacts, which ends-up hampering the image registration process. Previous studies addressed this by integrating additional image processing steps into the registration procedure. However, these steps are usually designed for particular image acquisition schemes, therefore limiting their use on a case-by-case basis. In the current study we address CT to CBCT and CBCT to CBCT registration by the means of the recently proposed EVolution registration algorithm. Contrary to previous approaches, EVolution does not require the integration of additional image processing steps in the registration scheme. Moreover, the algorithm requires a low number of input parameters, is easily parallelizable and provides an elastic deformation on a point-by-point basis. Results have shown that relative to a pure CT-based registration, the intrinsic artifacts present in typical CBCT images only have a sub-millimeter impact on the accuracy and precision of the estimated deformation. In addition, the algorithm has low computational requirements, which are compatible with online image-based guidance of EBRT treatments.

New Language and Old Problems in Breast Cancer Radiotherapy.

PubMed

Chiricuţă, Ion Christian

2017-01-01

New developments in breast cancer radiotherapy make possible new standards in treatment recommandations based on international guidelines. Developments in radiotherapy irradiation techniques from 2D to 3D-Conformal RT and to IMRT (Intensity Modulated Arc Therapy) make possible to reduce the usual side effects on the organs at risk as: skin, lung, miocard, bone, esophagus and brahial plexus. Dispite of all these progresses acute and late side effects are present. Side effects are as old as the radiotherapy was used. New solutions are available now by improving irradiation techniques. New techniques as sentinel node procedure (SNP) or partial breast irradiation (PBRT) and immediate breast reconstruction with silicon implants (IBRIS) make necessary new considerations regarding the target volume delineations. A new language for definition of gross tumor volume (GTV), clinical target volume (CTV) based on the new diagnostic methods as PET/CT,nonaparticle MRI will have real impact on target delineation and irradiation techniques. "The new common language in breast cancer therapy" would be the first step to improve the endresults and finally the quality of life of the patients. Celsius.

Regional Lung Ventilation Analysis Using Temporally Resolved Magnetic Resonance Imaging.

PubMed

Kolb, Christoph; Wetscherek, Andreas; Buzan, Maria Teodora; Werner, René; Rank, Christopher M; Kachelrie, Marc; Kreuter, Michael; Dinkel, Julien; Heuel, Claus Peter; Maier-Hein, Klaus

We propose a computer-aided method for regional ventilation analysis and observation of lung diseases in temporally resolved magnetic resonance imaging (4D MRI). A shape model-based segmentation and registration workflow was used to create an atlas-derived reference system in which regional tissue motion can be quantified and multimodal image data can be compared regionally. Model-based temporal registration of the lung surfaces in 4D MRI data was compared with the registration of 4D computed tomography (CT) images. A ventilation analysis was performed on 4D MR images of patients with lung fibrosis; 4D MR ventilation maps were compared with corresponding diagnostic 3D CT images of the patients and 4D CT maps of subjects without impaired lung function (serving as reference). Comparison between the computed patient-specific 4D MR regional ventilation maps and diagnostic CT images shows good correlation in conspicuous regions. Comparison to 4D CT-derived ventilation maps supports the plausibility of the 4D MR maps. Dynamic MRI-based flow-volume loops and spirograms further visualize the free-breathing behavior. The proposed methods allow for 4D MR-based regional analysis of tissue dynamics and ventilation in spontaneous breathing and comparison of patient data. The proposed atlas-based reference coordinate system provides an automated manner of annotating and comparing multimodal lung image data.

Radiotherapy treatment planning: benefits of CT-MR image registration and fusion in tumor volume delineation.

PubMed

Djan, Igor; Petrović, Borislava; Erak, Marko; Nikolić, Ivan; Lucić, Silvija

2013-08-01

Development of imaging techniques, computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET), made great impact on radiotherapy treatment planning by improving the localization of target volumes. Improved localization allows better local control of tumor volumes, but also minimizes geographical misses. Mutual information is obtained by registration and fusion of images achieved manually or automatically. The aim of this study was to validate the CT-MRI image fusion method and compare delineation obtained by CT versus CT-MRI image fusion. The image fusion software (XIO CMS 4.50.0) was applied to delineate 16 patients. The patients were scanned on CT and MRI in the treatment position within an immobilization device before the initial treatment. The gross tumor volume (GTV) and clinical target volume (CTV) were delineated on CT alone and on CT+MRI images consecutively and image fusion was obtained. Image fusion showed that CTV delineated on a CT image study set is mainly inadequate for treatment planning, in comparison with CTV delineated on CT-MRI fused image study set. Fusion of different modalities enables the most accurate target volume delineation. This study shows that registration and image fusion allows precise target localization in terms of GTV and CTV and local disease control.

Modeling of body tissues for Monte Carlo simulation of radiotherapy treatments planned with conventional x-ray CT systems

NASA Astrophysics Data System (ADS)

Kanematsu, Nobuyuki; Inaniwa, Taku; Nakao, Minoru

2016-07-01

In the conventional procedure for accurate Monte Carlo simulation of radiotherapy, a CT number given to each pixel of a patient image is directly converted to mass density and elemental composition using their respective functions that have been calibrated specifically for the relevant x-ray CT system. We propose an alternative approach that is a conversion in two steps: the first from CT number to density and the second from density to composition. Based on the latest compilation of standard tissues for reference adult male and female phantoms, we sorted the standard tissues into groups by mass density and defined the representative tissues by averaging the material properties per group. With these representative tissues, we formulated polyline relations between mass density and each of the following; electron density, stopping-power ratio and elemental densities. We also revised a procedure of stoichiometric calibration for CT-number conversion and demonstrated the two-step conversion method for a theoretically emulated CT system with hypothetical 80 keV photons. For the standard tissues, high correlation was generally observed between mass density and the other densities excluding those of C and O for the light spongiosa tissues between 1.0 g cm-3 and 1.1 g cm-3 occupying 1% of the human body mass. The polylines fitted to the dominant tissues were generally consistent with similar formulations in the literature. The two-step conversion procedure was demonstrated to be practical and will potentially facilitate Monte Carlo simulation for treatment planning and for retrospective analysis of treatment plans with little impact on the management of planning CT systems.

Female pelvic synthetic CT generation based on joint intensity and shape analysis

NASA Astrophysics Data System (ADS)

Liu, Lianli; Jolly, Shruti; Cao, Yue; Vineberg, Karen; Fessler, Jeffrey A.; Balter, James M.

2017-04-01

Using MRI for radiotherapy treatment planning and image guidance is appealing as it provides superior soft tissue information over CT scans and avoids possible systematic errors introduced by aligning MR to CT images. This study presents a method that generates Synthetic CT (MRCT) volumes by performing probabilistic tissue classification of voxels from MRI data using a single imaging sequence (T1 Dixon). The intensity overlap between different tissues on MR images, a major challenge for voxel-based MRCT generation methods, is addressed by adding bone shape information to an intensity-based classification scheme. A simple pelvic bone shape model, built from principal component analysis of pelvis shape from 30 CT image volumes, is fitted to the MR volumes. The shape model generates a rough bone mask that excludes air and covers bone along with some surrounding soft tissues. Air regions are identified and masked out from the tissue classification process by intensity thresholding outside the bone mask. A regularization term is added to the fuzzy c-means classification scheme that constrains voxels outside the bone mask from being assigned memberships in the bone class. MRCT image volumes are generated by multiplying the probability of each voxel being represented in each class with assigned attenuation values of the corresponding class and summing the result across all classes. The MRCT images presented intensity distributions similar to CT images with a mean absolute error of 13.7 HU for muscle, 15.9 HU for fat, 49.1 HU for intra-pelvic soft tissues, 129.1 HU for marrow and 274.4 HU for bony tissues across 9 patients. Volumetric modulated arc therapy (VMAT) plans were optimized using MRCT-derived electron densities, and doses were recalculated using corresponding CT-derived density grids. Dose differences to planning target volumes were small with mean/standard deviation of 0.21/0.42 Gy for D0.5cc and 0.29/0.33 Gy for D99%. The results demonstrate the accuracy of the method and its potential in supporting MRI only radiotherapy treatment planning.

Automatic lumbar spine measurement in CT images

NASA Astrophysics Data System (ADS)

Mao, Yunxiang; Zheng, Dong; Liao, Shu; Peng, Zhigang; Yan, Ruyi; Liu, Junhua; Dong, Zhongxing; Gong, Liyan; Zhou, Xiang Sean; Zhan, Yiqiang; Fei, Jun

2017-03-01

Accurate lumbar spine measurement in CT images provides an essential way for quantitative spinal diseases analysis such as spondylolisthesis and scoliosis. In today's clinical workflow, the measurements are manually performed by radiologists and surgeons, which is time consuming and irreproducible. Therefore, automatic and accurate lumbar spine measurement algorithm becomes highly desirable. In this study, we propose a method to automatically calculate five different lumbar spine measurements in CT images. There are three main stages of the proposed method: First, a learning based spine labeling method, which integrates both the image appearance and spine geometry information, is used to detect lumbar and sacrum vertebrae in CT images. Then, a multiatlases based image segmentation method is used to segment each lumbar vertebra and the sacrum based on the detection result. Finally, measurements are derived from the segmentation result of each vertebra. Our method has been evaluated on 138 spinal CT scans to automatically calculate five widely used clinical spine measurements. Experimental results show that our method can achieve more than 90% success rates across all the measurements. Our method also significantly improves the measurement efficiency compared to manual measurements. Besides benefiting the routine clinical diagnosis of spinal diseases, our method also enables the large scale data analytics for scientific and clinical researches.

TU-AB-202-07: A Novel Method for Registration of Mid-Treatment PET/CT Images Under Conditions of Tumor Regression for Patients with Locally Advanced Lung Cancers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharifi, Hoda; Department of Physics, Oakland University, Rochester, MI; Zhang, Hong

Purpose: In PET-guided adaptive radiotherapy (RT), changes in the metabolic activity at individual voxels cannot be derived until the duringtreatment CT images are appropriately registered to pre-treatment CT images. However, deformable image registration (DIR) usually does not preserve tumor volume. This may induce errors when comparing to the target. The aim of this study was to develop a DIR-integrated mechanical modeling technique to track radiation-induced metabolic changes on PET images. Methods: Three patients with non-small cell lung cancer (NSCLC) were treated with adaptive radiotherapy under RTOG 1106. Two PET/CT image sets were acquired 2 weeks before RT and 18 fractionsmore » after the start of treatment. DIR was performed to register the during-RT CT to the pre-RT CT using a B-spline algorithm and the resultant displacements in the region of tumor were remodeled using a hybrid finite element method (FEM). Gross tumor volume (GTV) was delineated on the during-RT PET/CT image sets and deformed using the 3D deformation vector fields generated by the CT-based registrations. Metabolic tumor volume (MTV) was calculated using the pre- and during–RT image set. The quality of the PET mapping was evaluated based on the constancy of the mapped MTV and landmark comparison. Results: The B-spline-based registrations changed MTVs by 7.3%, 4.6% and −5.9% for the 3 patients and the correspondent changes for the hybrid FEM method −2.9%, 1% and 6.3%, respectively. Landmark comparisons were used to evaluate the Rigid, B-Spline, and hybrid FEM registrations with the mean errors of 10.1 ± 1.6 mm, 4.4 ± 0.4 mm, and 3.6 ± 0.4 mm for three patients. The hybrid FEM method outperforms the B-Spline-only registration for patients with tumor regression Conclusion: The hybrid FEM modeling technique improves the B-Spline registrations in tumor regions. This technique may help compare metabolic activities between two PET/CT images with regressing tumors. The author gratefully acknowledges the financial support from the National Institutes of Health Grant.« less

Predicting location of recurrence using FDG, FLT, and Cu-ATSM PET in canine sinonasal tumors treated with radiotherapy

NASA Astrophysics Data System (ADS)

Bradshaw, Tyler; Fu, Rau; Bowen, Stephen; Zhu, Jun; Forrest, Lisa; Jeraj, Robert

2015-07-01

Dose painting relies on the ability of functional imaging to identify resistant tumor subvolumes to be targeted for additional boosting. This work assessed the ability of FDG, FLT, and Cu-ATSM PET imaging to predict the locations of residual FDG PET in canine tumors following radiotherapy. Nineteen canines with spontaneous sinonasal tumors underwent PET/CT imaging with radiotracers FDG, FLT, and Cu-ATSM prior to hypofractionated radiotherapy. Therapy consisted of 10 fractions of 4.2 Gy to the sinonasal cavity with or without an integrated boost of 0.8 Gy to the GTV. Patients had an additional FLT PET/CT scan after fraction 2, a Cu-ATSM PET/CT scan after fraction 3, and follow-up FDG PET/CT scans after radiotherapy. Following image registration, simple and multiple linear and logistic voxel regressions were performed to assess how well pre- and mid-treatment PET imaging predicted post-treatment FDG uptake. R2 and pseudo R2 were used to assess the goodness of fits. For simple linear regression models, regression coefficients for all pre- and mid-treatment PET images were significantly positive across the population (P < 0.05). However, there was large variability among patients in goodness of fits: R2 ranged from 0.00 to 0.85, with a median of 0.12. Results for logistic regression models were similar. Multiple linear regression models resulted in better fits (median R2 = 0.31), but there was still large variability between patients in R2. The R2 from regression models for different predictor variables were highly correlated across patients (R ≈ 0.8), indicating tumors that were poorly predicted with one tracer were also poorly predicted by other tracers. In conclusion, the high inter-patient variability in goodness of fits indicates that PET was able to predict locations of residual tumor in some patients, but not others. This suggests not all patients would be good candidates for dose painting based on a single biological target.

Predicting location of recurrence using FDG, FLT, and Cu-ATSM PET in canine sinonasal tumors treated with radiotherapy.

PubMed

Bradshaw, Tyler; Fu, Rau; Bowen, Stephen; Zhu, Jun; Forrest, Lisa; Jeraj, Robert

2015-07-07

Dose painting relies on the ability of functional imaging to identify resistant tumor subvolumes to be targeted for additional boosting. This work assessed the ability of FDG, FLT, and Cu-ATSM PET imaging to predict the locations of residual FDG PET in canine tumors following radiotherapy. Nineteen canines with spontaneous sinonasal tumors underwent PET/CT imaging with radiotracers FDG, FLT, and Cu-ATSM prior to hypofractionated radiotherapy. Therapy consisted of 10 fractions of 4.2 Gy to the sinonasal cavity with or without an integrated boost of 0.8 Gy to the GTV. Patients had an additional FLT PET/CT scan after fraction 2, a Cu-ATSM PET/CT scan after fraction 3, and follow-up FDG PET/CT scans after radiotherapy. Following image registration, simple and multiple linear and logistic voxel regressions were performed to assess how well pre- and mid-treatment PET imaging predicted post-treatment FDG uptake. R(2) and pseudo R(2) were used to assess the goodness of fits. For simple linear regression models, regression coefficients for all pre- and mid-treatment PET images were significantly positive across the population (P < 0.05). However, there was large variability among patients in goodness of fits: R(2) ranged from 0.00 to 0.85, with a median of 0.12. Results for logistic regression models were similar. Multiple linear regression models resulted in better fits (median R(2) = 0.31), but there was still large variability between patients in R(2). The R(2) from regression models for different predictor variables were highly correlated across patients (R ≈ 0.8), indicating tumors that were poorly predicted with one tracer were also poorly predicted by other tracers. In conclusion, the high inter-patient variability in goodness of fits indicates that PET was able to predict locations of residual tumor in some patients, but not others. This suggests not all patients would be good candidates for dose painting based on a single biological target.

Generating patient specific pseudo-CT of the head from MR using atlas-based regression

NASA Astrophysics Data System (ADS)

Sjölund, J.; Forsberg, D.; Andersson, M.; Knutsson, H.

2015-01-01

Radiotherapy planning and attenuation correction of PET images require simulation of radiation transport. The necessary physical properties are typically derived from computed tomography (CT) images, but in some cases, including stereotactic neurosurgery and combined PET/MR imaging, only magnetic resonance (MR) images are available. With these applications in mind, we describe how a realistic, patient-specific, pseudo-CT of the head can be derived from anatomical MR images. We refer to the method as atlas-based regression, because of its similarity to atlas-based segmentation. Given a target MR and an atlas database comprising MR and CT pairs, atlas-based regression works by registering each atlas MR to the target MR, applying the resulting displacement fields to the corresponding atlas CTs and, finally, fusing the deformed atlas CTs into a single pseudo-CT. We use a deformable registration algorithm known as the Morphon and augment it with a certainty mask that allows a tailoring of the influence certain regions are allowed to have on the registration. Moreover, we propose a novel method of fusion, wherein the collection of deformed CTs is iteratively registered to their joint mean and find that the resulting mean CT becomes more similar to the target CT. However, the voxelwise median provided even better results; at least as good as earlier work that required special MR imaging techniques. This makes atlas-based regression a good candidate for clinical use.

[(18)F]Choline PET/CT and stereotactic body radiotherapy on treatment decision making of oligometastatic prostate cancer patients: preliminary results.

PubMed

Pasqualetti, Francesco; Panichi, Marco; Sainato, Aldo; Matteucci, Fabrizio; Galli, Luca; Cocuzza, Paola; Ferrazza, Patrizia; Coraggio, Gabriele; Pasqualetti, Giuseppe; Derosa, Lisa; Sollini, Martina; Mannelli, Lorenzo; Ortori, Simona; Monzani, Fabio; Ricci, Sergio; Greco, Carlo; Fabrini, Maria Grazia; Erba, Paola Anna

2016-01-22

A new entity of patients with recurrent prostate cancer limited to a small number of active metastatic lesions is having growing interest: the oligometastatic patients. Patients with oligometastatic disease could eventually be managed by treating all the active lesions with local therapy, i.e. either surgery or ablative stereotactic body radiotherapy. This study aims to assess the impact of [(18)F]Choline ([(18)F]FMCH) PET/CT and the use stereotactic body radiotherapy (SBRT) in patients (pts) with oligometastatic prostate cancer (PCa). Twenty-nine pts with oligometastatic PCa (≤3 synchronous active lesions detected with [(18)F]FMCHPET/CT) were treated with repeated salvage SBRT until disease progression (development of > three active synchronous metastases). Primary endpoint was systemic therapy-free survival measured from the baseline [(18)F]FMCHPET/CT. A total of 45 lesions were treated with SBRT. After a median follow-up of 11.5 months (range 3-40 months), 20 pts were still in the study and did not receive any systemic therapy. Nine pts started systemic therapy, and the median time of the primary endpoint was 39.7 months (CI 12.20-62.14 months). No grade 3 or 4 toxicity was recorded. Repeated salvage [(18)F]FMCHPET/CT-guided SBRT is well tolerated and could defer the beginning of systemic therapy in selected patients with oligometastatic PCa.

WE-DE-BRA-03: Construction of An Ultrasound Guidance Platform for Image-Guided Radiotherapy with the Intent to Treat Transitional Cell Carcinoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sick, J; Rancilio, N; Fulkerson, C

Purpose: Ultrasound (US) is a noninvasive, nonradiographic imaging technique with high spatial and temporal resolution that can be used for localizing soft-tissue structures and tumors in real-time during radiotherapy (inter- and intra-fraction). A detailed methodology integrating 3D-US within RT is presented. This method is easier to adopt into current treatment protocol than current US based systems and reduces user variability for image acquisition, thus eliminating transducer induced changes that limit CT planning system. Methods: We designed an in-house integrated US manipulator and platform to relate CT, 3D-US and linear accelerator coordinate systems. To validate the platform, an agar-based phantom withmore » measured densities and speed-of-sound consistent with tissues surrounding the bladder, was rotated (0–45°) resulting in translations (up to 55mm) relative to the CT and US coordinate systems. After acquiring and integrating CT and US images into the treatment planning system, US-to-US and US-to-CT images were co-registered to re-align the phantom relative to the linear accelerator. Errors in the transformation matrix components were calculate to determine precision of this method under different patient positions. Results: Statistical errors from US-US registrations for different patient orientations ranged from 0.06–1.66mm for x, y, and z translational components, and 0.00–1.05° for rotational components. Statistical errors from US-CT registrations were 0.23–1.18mm for the x, y and z translational components, and 0.08–2.52° for the rotational components. Conclusion: Based on our result, this is consistent with currently used techniques for positioning prostate patients if couch re-positioning is less than a 5 degree rotation. We are now testing this on a dog patient to obtain both inter and intra-fractional positional errors. Additional design considerations include the future use of ultrasound-based functionality (photoacoustics, radioacoustics, Doppler) to monitor blood flow and hypoxia and/or in-vivo dosimetry for applications in other therapeutic techniques, such as hyperthermia, anti-angiogenesis, and particle therapy.« less

Projection-data based temporal maximum attenuation computed tomography: determination of internal target volume for lung cancer against intra-fraction motion

NASA Astrophysics Data System (ADS)

Mori, Shinichiro; Kanematsu, Nobuyuki; Asakura, Hiroshi; Endo, Masahiro

2007-02-01

The concept of internal target volume (ITV) is highly significant in radiotherapy for the lung, an organ which is hampered by organ motion. To date, different methods to obtain the ITV have been published and are therefore available. To define ITV, we developed a new method by adapting a time filter to the four-dimensional CT scan technique (4DCT) which is projection-data processing (4D projection data maximum attenuation (4DPM)), and compared it with reconstructed image processing (4D image maximum intensity projection (4DIM)) using a phantom and clinical evaluations. 4DIM and 4DPM captured accurate maximum intensity volume (MIV), that is tumour encompassing volume, easily. Although 4DIM increased the CT number 1.8 times higher than 4DPM, 4DPM provided the original tumour CT number for MIV via a reconstruction algorithm. In the patient with lung fibrosis honeycomb, the MIV with 4DIM is 0.7 cm larger than that for cine imaging in the cranio-caudal direction. 4DPM therefore provided an accurate MIV independent of patient characteristics and reconstruction conditions. These findings indicate the usefulness of 4DPM in determining ITV in radiotherapy.

Quantification of confounding factors in MRI-based dose calculations as applied to prostate IMRT

NASA Astrophysics Data System (ADS)

Maspero, Matteo; Seevinck, Peter R.; Schubert, Gerald; Hoesl, Michaela A. U.; van Asselen, Bram; Viergever, Max A.; Lagendijk, Jan J. W.; Meijer, Gert J.; van den Berg, Cornelis A. T.

2017-02-01

Magnetic resonance (MR)-only radiotherapy treatment planning requires pseudo-CT (pCT) images to enable MR-based dose calculations. To verify the accuracy of MR-based dose calculations, institutions interested in introducing MR-only planning will have to compare pCT-based and computer tomography (CT)-based dose calculations. However, interpreting such comparison studies may be challenging, since potential differences arise from a range of confounding factors which are not necessarily specific to MR-only planning. Therefore, the aim of this study is to identify and quantify the contribution of factors confounding dosimetric accuracy estimation in comparison studies between CT and pCT. The following factors were distinguished: set-up and positioning differences between imaging sessions, MR-related geometric inaccuracy, pCT generation, use of specific calibration curves to convert pCT into electron density information, and registration errors. The study comprised fourteen prostate cancer patients who underwent CT/MRI-based treatment planning. To enable pCT generation, a commercial solution (MRCAT, Philips Healthcare, Vantaa, Finland) was adopted. IMRT plans were calculated on CT (gold standard) and pCTs. Dose difference maps in a high dose region (CTV) and in the body volume were evaluated, and the contribution to dose errors of possible confounding factors was individually quantified. We found that the largest confounding factor leading to dose difference was the use of different calibration curves to convert pCT and CT into electron density (0.7%). The second largest factor was the pCT generation which resulted in pCT stratified into a fixed number of tissue classes (0.16%). Inter-scan differences due to patient repositioning, MR-related geometric inaccuracy, and registration errors did not significantly contribute to dose differences (0.01%). The proposed approach successfully identified and quantified the factors confounding accurate MRI-based dose calculation in the prostate. This study will be valuable for institutions interested in introducing MR-only dose planning in their clinical practice.

Atlas Based Segmentation and Mapping of Organs at Risk from Planning CT for the Development of Voxel-Wise Predictive Models of Toxicity in Prostate Radiotherapy

NASA Astrophysics Data System (ADS)

Acosta, Oscar; Dowling, Jason; Cazoulat, Guillaume; Simon, Antoine; Salvado, Olivier; de Crevoisier, Renaud; Haigron, Pascal

The prediction of toxicity is crucial to managing prostate cancer radiotherapy (RT). This prediction is classically organ wise and based on the dose volume histograms (DVH) computed during the planning step, and using for example the mathematical Lyman Normal Tissue Complication Probability (NTCP) model. However, these models lack spatial accuracy, do not take into account deformations and may be inappropiate to explain toxicity events related with the distribution of the delivered dose. Producing voxel wise statistical models of toxicity might help to explain the risks linked to the dose spatial distribution but is challenging due to the difficulties lying on the mapping of organs and dose in a common template. In this paper we investigate the use of atlas based methods to perform the non-rigid mapping and segmentation of the individuals' organs at risk (OAR) from CT scans. To build a labeled atlas, 19 CT scans were selected from a population of patients treated for prostate cancer by radiotherapy. The prostate and the OAR (Rectum, Bladder, Bones) were then manually delineated by an expert and constituted the training data. After a number of affine and non rigid registration iterations, an average image (template) representing the whole population was obtained. The amount of consensus between labels was used to generate probabilistic maps for each organ. We validated the accuracy of the approach by segmenting the organs using the training data in a leave one out scheme. The agreement between the volumes after deformable registration and the manually segmented organs was on average above 60% for the organs at risk. The proposed methodology provides a way to map the organs from a whole population on a single template and sets the stage to perform further voxel wise analysis. With this method new and accurate predictive models of toxicity will be built.

SU-E-T-419: Workflow and FMEA in a New Proton Therapy (PT) Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, C; Wessels, B; Hamilton, H

2014-06-01

Purpose: Workflow is an important component in the operational planning of a new proton facility. By integrating the concept of failure mode and effect analysis (FMEA) and traditional QA requirements, a workflow for a proton therapy treatment course is set up. This workflow serves as the blue print for the planning of computer hardware/software requirements and network flow. A slight modification of the workflow generates a process map(PM) for FMEA and the planning of QA program in PT. Methods: A flowchart is first developed outlining the sequence of processes involved in a PT treatment course. Each process consists of amore » number of sub-processes to encompass a broad scope of treatment and QA procedures. For each subprocess, the personnel involved, the equipment needed and the computer hardware/software as well as network requirements are defined by a team of clinical staff, administrators and IT personnel. Results: Eleven intermediate processes with a total of 70 sub-processes involved in a PT treatment course are identified. The number of sub-processes varies, ranging from 2-12. The sub-processes within each process are used for the operational planning. For example, in the CT-Sim process, there are 12 sub-processes: three involve data entry/retrieval from a record-and-verify system, two controlled by the CT computer, two require department/hospital network, and the other five are setup procedures. IT then decides the number of computers needed and the software and network requirement. By removing the traditional QA procedures from the workflow, a PM is generated for FMEA analysis to design a QA program for PT. Conclusion: Significant efforts are involved in the development of the workflow in a PT treatment course. Our hybrid model of combining FMEA and traditional QA program serves a duo purpose of efficient operational planning and designing of a QA program in PT.« less

A dedicated software application for treatment verification with off-line PET/CT imaging at the Heidelberg Ion Beam Therapy Center

NASA Astrophysics Data System (ADS)

Chen, W.; Bauer, J.; Kurz, C.; Tessonnier, T.; Handrack, J.; Haberer, T.; Debus, J.; Parodi, K.

2017-01-01

We present the workflow of the offline-PET based range verification method used at the Heidelberg Ion Beam Therapy Center, detailing the functionalities of an in-house developed software application, SimInterface14, with which range analysis is performed. Moreover, we introduce the design of a decision support system assessing uncertainties and facilitating physicians in decisions making for plan adaptation.

Ultrasound-Based Guidance for Partial Breast Irradiation Therapy

DTIC Science & Technology

2011-01-01

and also are inexpensive. b. Collect US data from patient before the PBI treatment at the same time that CT is collected (months 2-14). We...introduces minimal divergence from the original workflow of PBI treatment. We have an approved institutional review board (IRB) protocol to obtain B...irradiation of only the in- volved area of the breast, partial breast irradiation ( PBI ), is as effective as whole breast irradiation [1]. Benefits of PBI

Accurate Analysis of the Change in Volume, Location, and Shape of Metastatic Cervical Lymph Nodes During Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takao, Seishin, E-mail: takao@mech-me.eng.hokudai.ac.jp; Tadano, Shigeru; Taguchi, Hiroshi

2011-11-01

Purpose: To establish a method for the accurate acquisition and analysis of the variations in tumor volume, location, and three-dimensional (3D) shape of tumors during radiotherapy in the era of image-guided radiotherapy. Methods and Materials: Finite element models of lymph nodes were developed based on computed tomography (CT) images taken before the start of treatment and every week during the treatment period. A surface geometry map with a volumetric scale was adopted and used for the analysis. Six metastatic cervical lymph nodes, 3.5 to 55.1 cm{sup 3} before treatment, in 6 patients with head and neck carcinomas were analyzed inmore » this study. Three fiducial markers implanted in mouthpieces were used for the fusion of CT images. Changes in the location of the lymph nodes were measured on the basis of these fiducial markers. Results: The surface geometry maps showed convex regions in red and concave regions in blue to ensure that the characteristics of the 3D tumor geometries are simply understood visually. After the irradiation of 66 to 70 Gy in 2 Gy daily doses, the patterns of the colors had not changed significantly, and the maps before and during treatment were strongly correlated (average correlation coefficient was 0.808), suggesting that the tumors shrank uniformly, maintaining the original characteristics of the shapes in all 6 patients. The movement of the gravitational center of the lymph nodes during the treatment period was everywhere less than {+-}5 mm except in 1 patient, in whom the change reached nearly 10 mm. Conclusions: The surface geometry map was useful for an accurate evaluation of the changes in volume and 3D shapes of metastatic lymph nodes. The fusion of the initial and follow-up CT images based on fiducial markers enabled an analysis of changes in the location of the targets. Metastatic cervical lymph nodes in patients were suggested to decrease in size without significant changes in the 3D shape during radiotherapy. The movements of the gravitational center of the lymph nodes were almost all less than {+-}5 mm.« less

Deformation Prediction and Geometrical Modeling of Head and Neck Cancer Tumor: A Data Mining Approach

NASA Astrophysics Data System (ADS)

Azimi, Maryam

Radiation therapy has been used in the treatment of cancer tumors for several years and many cancer patients receive radiotherapy. It may be used as primary therapy or with a combination of surgery or other kinds of therapy such as chemotherapy, hormone therapy or some mixture of the three. The treatment objective is to destroy cancer cells or shrink the tumor by planning an adequate radiation dose to the desired target without damaging the normal tissues. By using the pre-treatment Computer Tomography (CT) images, most of the radiotherapy planning systems design the target and assume that the size of the tumor will not change throughout the treatment course, which takes 5 to 7 weeks. Based on this assumption, the total amount of radiation is planned and fractionated for the daily dose required to be delivered to the patient's body. However, this assumption is flawed because the patients receiving radiotherapy have marked changes in tumor geometry during the treatment period. Therefore, there is a critical need to understand the changes of the tumor shape and size over time during the course of radiotherapy in order to prevent significant effects of inaccuracy in the planning. In this research, a methodology is proposed in order to monitor and predict daily (fraction day) tumor volume and surface changes of head and neck cancer tumors during the entire treatment period. In the proposed method, geometrical modeling and data mining techniques will be used rather than repetitive CT scans data to predict the tumor deformation for radiation planning. Clinical patient data were obtained from the University of Texas-MD Anderson Cancer Center (MDACC). In the first step, by using CT scan data, the tumor's progressive geometric changes during the treatment period are quantified. The next step relates to using regression analysis in order to develop predictive models for tumor geometry based on the geometric analysis results and the patients' selected attributes (age, weight, stage, etc.). Moreover, repeated measure analyses have been applied to identify the effects of patients' selected attributes on tumor deformation. The main goal of the proposed methodology is increasing the accuracy of each therapy and quality of life for patients.

SU-F-I-32: Organ Doses from Pediatric Head CT Scan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, H; Liu, Q; Qiu, J

Purpose: To evaluate the organ doses of pediatric patients who undergoing head CT scan using Monte Carlo (MC) simulation and compare it with measurements in anthropomorphic child phantom.. Methods: A ten years old children voxel phantom was developed from CT images, the voxel size of the phantom was 2mm*2mm*2mm. Organ doses from head CT scan were simulated using MCNPX software, 180 detectors were placed in the voxel phantom to tally the doses of the represented tissues or organs. When performing the simulation, 120 kVp and 88 mA were selected as the scan parameters. The scan range covered from the topmore » of the head to the end of the chain, this protocol was used at CT simulator for radiotherapy. To validate the simulated results, organ doses were measured with radiophotoluminescence (RPL) detectors, placed in the 28 organs of the 10 years old CIRS ATOM phantom. Results: The organ doses results matched well between MC simulation and phantom measurements. The eyes dose was showed to be as expected the highest organ dose: 28.11 mGy by simulation and 27.34 mGy by measurement respectively. Doses for organs not included in the scan volume were much lower than those included in the scan volume, thymus doses were observed more than 10 mGy due the CT protocol for radiotherapy covered more body part than routine head CT scan. Conclusion: As the eyes are superficial organs, they may receive the highest radiation dose during the CT scan. Considering the relatively high radio sensitivity, using shielding material or organ based tube current modulation technique should be encouraged to reduce the eye radiation risks. Scan range was one of the most important factors that affects the organ doses during the CT scan. Use as short as reasonably possible scan range should be helpful to reduce the patient radiation dose. This work was supported by the National Natural Science Foundation of China(11475047)« less

Target volume definition for post prostatectomy radiotherapy: Do the consensus guidelines correctly define the inferior border of the CTV?

PubMed

Manji, Mo; Crook, Juanita; Schmid, Matt; Rajapakshe, Rasika

2016-01-01

We compare urethrogram delineation of the caudal aspect of the anastomosis to the recommended guidelines of post prostatectomy radiotherapy. Level one evidence has established the indications for, and importance of, adjuvant radiotherapy following radical prostatectomy. Several guidelines have recently addressed delineation of the prostate bed target volume including identification of the vesico-urethral anastomosis, taken as the first CT slice caudal to visible urine in the bladder neck. The inferior border of clinical target volume is then variably defined 5-12 mm below this anastomosis or 15 mm cranial to the penile bulb. Thirty-three patients who received adjuvant radiotherapy following radical prostatectomy were reviewed. All underwent planning CT with urethrogram. The authors (MM, JC) independently identified the CT slice caudal to the last slice showing urine in the bladder neck (called the CT Reference Slice), and measured the distance between this and the tip of the urethrogram cone. Five patients also had a diagnostic MRI at the time of CT planning to better visualize the anatomy. Sixty-six readings were obtained. The mean distance between the Bladder CT Reference Slice and the most cranial urethrogram contrast slice was 16.1 mm (MM 16.4 mm, JC 15.8 mm), range: 6.8-34.2 mm. The mean distance between the urethrogram tip and the ischial tuberosities was 19.9 mm (range 12.5-29.8 mm). The mean distance between the CT Reference Slice and the ischial tuberosities was 36.9 mm (range 28.3-52.4 mm). Guidelines for prostate bed radiation post prostatectomy have been developed after publication of the trials proving benefit of such treatment, and are thus untested. The anastomosis is a frequent site of local relapse but is variably defined by the existing guidelines, none of which take into account anatomic patient variation and all of which are at variance with urethrogram data. We recommend the use of planning urethrogram to better delineate the vesico-urethral junction and minimize the potential for geographic misses.

Prediction of the location and size of the stomach using patient characteristics for retrospective radiation dose estimation following radiotherapy

PubMed Central

Lamart, Stephanie; Imran, Rebecca; Simon, Steven L.; Doi, Kazutaka; Morton, Lindsay M.; Curtis, Rochelle E.; Lee, Choonik; Drozdovitch, Vladimir; Maass-Moreno, Roberto; Chen, Clara C.; Whatley, Millie; Miller, Donald L.; Pacak, Karel; Lee, Choonsik

2014-01-01

Following cancer radiotherapy, reconstruction of doses to organs, other than the target organ, is of interest for retrospective health risk studies. Reliable estimation of doses to organs that may be partially within or fully outside the treatment field requires reliable knowledge of the location and size of the organs, e.g., the stomach, which is at risk from abdominal irradiation. The stomach location and size are known to be highly variable between individuals, but have been little studied. Moreover, for treatments conducted years ago, medical images of patients are usually not available in medical records to locate the stomach. In light of the poor information available to locate the stomach in historical dose reconstructions, the purpose of this work was to investigate the variability of stomach location and size among adult male patients and to develop prediction models for the stomach location and size using predictor variables generally available in medical records of radiotherapy patients treated in the past. To collect data on stomach size and position, we segmented the contours of the stomach and of the skeleton on contemporary Computed Tomography (CT) images for 30 male patients in supine position. The location and size of the stomach was found to depend on body mass index (BMI), ponderal index (PI), and age. For example, the anteroposterior dimension of the stomach was found to increase with increasing BMI (≈0.25 cm per kg/m2) whereas its craniocaudal dimension decreased with increasing PI (≈ −3.3 cm per kg/m3) and its transverse dimension increased with increasing PI (≈ 2.5 cm per kg/m3). Using the prediction models, we generated three dimensional computational stomach models from a deformable hybrid phantom for three patients of different BMI. Based on a typical radiotherapy treatment, we simulated radiotherapy treatments on the predicted stomach models and on the CT images of the corresponding patients. Those dose calculations demonstrated good agreement between predicted and actual stomachs compared with doses derived from a reference model of the body that might be used in the absence of individual CT scan data. PMID:24301086

Prediction of the location and size of the stomach using patient characteristics for retrospective radiation dose estimation following radiotherapy

NASA Astrophysics Data System (ADS)

Lamart, Stephanie; Imran, Rebecca; Simon, Steven L.; Doi, Kazutaka; Morton, Lindsay M.; Curtis, Rochelle E.; Lee, Choonik; Drozdovitch, Vladimir; Maass-Moreno, Roberto; Chen, Clara C.; Whatley, Millie; Miller, Donald L.; Pacak, Karel; Lee, Choonsik

2013-12-01

Following cancer radiotherapy, reconstruction of doses to organs, other than the target organ, is of interest for retrospective health risk studies. Reliable estimation of doses to organs that may be partially within or fully outside the treatment field requires reliable knowledge of the location and size of the organs, e.g., the stomach, which is at risk from abdominal irradiation. The stomach location and size are known to be highly variable between individuals, but have been little studied. Moreover, for treatments conducted years ago, medical images of patients are usually not available in medical records to locate the stomach. In light of the poor information available to locate the stomach in historical dose reconstructions, the purpose of this work was to investigate the variability of stomach location and size among adult male patients and to develop prediction models for the stomach location and size using predictor variables generally available in medical records of radiotherapy patients treated in the past. To collect data on stomach size and position, we segmented the contours of the stomach and of the skeleton on contemporary computed tomography (CT) images for 30 male patients in supine position. The location and size of the stomach was found to depend on body mass index (BMI), ponderal index (PI), and age. For example, the anteroposterior dimension of the stomach was found to increase with increasing BMI (≈0.25 cm kg-1 m2) whereas its craniocaudal dimension decreased with increasing PI (≈-3.3 cm kg-1 m3) and its transverse dimension increased with increasing PI (≈2.5 cm kg-1 m3). Using the prediction models, we generated three-dimensional computational stomach models from a deformable hybrid phantom for three patients of different BMI. Based on a typical radiotherapy treatment, we simulated radiotherapy treatments on the predicted stomach models and on the CT images of the corresponding patients. Those dose calculations demonstrated good agreement between predicted and actual stomachs compared with doses derived from a reference model of the body that might be used in the absence of individual CT scan data.

MR-CBCT image-guided system for radiotherapy of orthotopic rat prostate tumors.

PubMed

Chiu, Tsuicheng D; Arai, Tatsuya J; Campbell Iii, James; Jiang, Steve B; Mason, Ralph P; Stojadinovic, Strahinja

2018-01-01

Multi-modality image-guided radiotherapy is the standard of care in contemporary cancer management; however, it is not common in preclinical settings due to both hardware and software limitations. Soft tissue lesions, such as orthotopic prostate tumors, are difficult to identify using cone beam computed tomography (CBCT) imaging alone. In this study, we characterized a research magnetic resonance (MR) scanner for preclinical studies and created a protocol for combined MR-CBCT image-guided small animal radiotherapy. Two in-house dual-modality, MR and CBCT compatible, phantoms were designed and manufactured using 3D printing technology. The phantoms were used for quality assurance tests and to facilitate end-to-end testing for combined preclinical MR and CBCT based treatment planning. MR and CBCT images of the phantoms were acquired utilizing a Varian 4.7 T scanner and XRad-225Cx irradiator, respectively. The geometry distortion was assessed by comparing MR images to phantom blueprints and CBCT. The corrected MR scans were co-registered with CBCT and subsequently used for treatment planning. The fidelity of 3D printed phantoms compared to the blueprint design yielded favorable agreement as verified with the CBCT measurements. The geometric distortion, which varied between -5% and 11% throughout the scanning volume, was substantially reduced to within 0.4% after correction. The distortion free MR images were co-registered with the corresponding CBCT images and imported into a commercial treatment planning software SmART Plan. The planning target volume (PTV) was on average 19% smaller when contoured on the corrected MR-CBCT images relative to raw images without distortion correction. An MR-CBCT based preclinical workflow was successfully designed and implemented for small animal radiotherapy. Combined MR-CBCT image-guided radiotherapy for preclinical research potentially delivers enhanced relevance to human radiotherapy for various disease sites. This novel protocol is wide-ranging and not limited to the orthotopic prostate tumor study presented in the study.

Influence of age on the pattern and outcome of external beam radiotherapy for clinically localized prostate cancer.

PubMed

Ogawa, Kazuhiko; Nakamura, Katsumasa; Onishi, Hiroshi; Koizumi, Masahiko; Sasaki, Tomonari; Araya, Masayuki; Miyabe, Yuuki; Otani, Yuuki; Teshima, Teruki

2006-01-01

The influence of age on the patterns and outcomes of external beam radiotherapy for clinically localized prostate cancer patients was examined. The Japanese Patterns of Care Study surveys were used to compare the processes and outcomes of radical external beam radiotherapy in 140 elderly patients (>75 years old) and 304 younger patients (<75 years old). Although the Karnofsky performance status was significantly different between elderly and younger patients, there were no significant differences in disease characteristics such as pretreatment PSA level, differentiation, Gleason combined score and clinical T stage. There were also no significant differences in the treatment characteristics such as CT-based treatment planning, conformal therapy, total radiation doses (both a median of 66.0 Gy) and hormonal therapy usage. Moreover, no significant differences in overall survival, biochemical relapse-free survival and late toxicity rates were observed between elderly and younger patients. Age did not influence the disease characteristics, patterns of external beam radiotherapy, survival and late toxicities for clinically localized prostate cancer patients. Therefore, radiotherapy could represent an important treatment modality for elderly patients as well as for younger ones.

Pre-operative segmentation of neck CT datasets for the planning of neck dissections

NASA Astrophysics Data System (ADS)

Cordes, Jeanette; Dornheim, Jana; Preim, Bernhard; Hertel, Ilka; Strauss, Gero

2006-03-01

For the pre-operative segmentation of CT neck datasets, we developed the software assistant NeckVision. The relevant anatomical structures for neck dissection planning can be segmented and the resulting patient-specific 3D-models are visualized afterwards in another software system for intervention planning. As a first step, we examined the appropriateness of elementary segmentation techniques based on gray values and contour information to extract the structures in the neck region from CT data. Region growing, interactive watershed transformation and live-wire are employed for segmentation of different target structures. It is also examined, which of the segmentation tasks can be automated. Based on this analysis, the software assistant NeckVision was developed to optimally support the workflow of image analysis for clinicians. The usability of NeckVision was tested within a first evaluation with four otorhinolaryngologists from the university hospital of Leipzig, four computer scientists from the university of Magdeburg and two laymen in both fields.

TH-E-202-02: The Use of Hypoxia PET Imaging for Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Humm, J.

2016-06-15

PET/CT is a very important imaging tool in the management of oncology patients. PET/CT has been applied for treatment planning and response evaluation in radiation therapy. This educational session will discuss: Pitfalls and remedies in PET/CT imaging for RT planning The use of hypoxia PET imaging for radiotherapy PET for tumor response evaluation The first presentation will address the issue of mis-registration between the CT and PET images in the thorax and the abdomen. We will discuss the challenges of respiratory gating and introduce an average CT technique to improve the registration for dose calculation and image-guidance in radiation therapy.more » The second presentation will discuss the use of hypoxia PET Imaging for radiation therapy. We will discuss various hypoxia radiotracers, the choice of clinical acquisition protocol (in particular a single late static acquisition versus a dynamic acquisition), and the compartmental modeling with different transfer rate constants explained. We will demonstrate applications of hypoxia imaging for dose escalation/de-escalation in clinical trials. The last presentation will discuss the use of PET/CT for tumor response evaluation. We will discuss anatomic response assessment vs. metabolic response assessment, visual evaluation and semi-quantitative evaluation, and limitations of current PET/CT assessment. We will summarize clinical trials using PET response in guiding adaptive radiotherapy. Finally, we will summarize recent advancements in PET/CT radiomics and non-FDG PET tracers for response assessment. Learning Objectives: Identify the causes of mis-registration of CT and PET images in PET/CT, and review the strategies to remedy the issue. Understand the basics of PET imaging of tumor hypoxia (radiotracers, how PET measures the hypoxia selective uptake, imaging protocols, applications in chemo-radiation therapy). Understand the basics of dynamic PET imaging, compartmental modeling and parametric images. Understand the basics of using FDG PET/CT for tumor response evaluation. Learn about recent advancement in PET/CT radiomics and non-FDG PET tracers for response assessment. This work was supported in part by the National Cancer Institute Grants R01CA172638.; W. Lu, This work was supported in part by the National Cancer Institute Grants R01CA172638.« less

Defining the value of magnetic resonance imaging in prostate brachytherapy using time-driven activity-based costing.

PubMed

Thaker, Nikhil G; Orio, Peter F; Potters, Louis

Magnetic resonance imaging (MRI) simulation and planning for prostate brachytherapy (PBT) may deliver potential clinical benefits but at an unknown cost to the provider and healthcare system. Time-driven activity-based costing (TDABC) is an innovative bottom-up costing tool in healthcare that can be used to measure the actual consumption of resources required over the full cycle of care. TDABC analysis was conducted to compare patient-level costs for an MRI-based versus traditional PBT workflow. TDABC cost was only 1% higher for the MRI-based workflow, and utilization of MRI allowed for cost shifting from other imaging modalities, such as CT and ultrasound, to MRI during the PBT process. Future initiatives will be required to follow the costs of care over longer periods of time to determine if improvements in outcomes and toxicities with an MRI-based approach lead to lower resource utilization and spending over the long-term. Understanding provider costs will become important as healthcare reform transitions to value-based purchasing and other alternative payment models. Copyright © 2016 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Radiotherapy volume delineation using dynamic [18F]-FDG PET/CT imaging in patients with oropharyngeal cancer: a pilot study.

PubMed

Silvoniemi, Antti; Din, Mueez U; Suilamo, Sami; Shepherd, Tony; Minn, Heikki

2016-11-01

Delineation of gross tumour volume in 3D is a critical step in the radiotherapy (RT) treatment planning for oropharyngeal cancer (OPC). Static [ 18 F]-FDG PET/CT imaging has been suggested as a method to improve the reproducibility of tumour delineation, but it suffers from low specificity. We undertook this pilot study in which dynamic features in time-activity curves (TACs) of [ 18 F]-FDG PET/CT images were applied to help the discrimination of tumour from inflammation and adjacent normal tissue. Five patients with OPC underwent dynamic [ 18 F]-FDG PET/CT imaging in treatment position. Voxel-by-voxel analysis was performed to evaluate seven dynamic features developed with the knowledge of differences in glucose metabolism in different tissue types and visual inspection of TACs. The Gaussian mixture model and K-means algorithms were used to evaluate the performance of the dynamic features in discriminating tumour voxels compared to the performance of standardized uptake values obtained from static imaging. Some dynamic features showed a trend towards discrimination of different metabolic areas but lack of consistency means that clinical application is not recommended based on these results alone. Impact of inflammatory tissue remains a problem for volume delineation in RT of OPC, but a simple dynamic imaging protocol proved practicable and enabled simple data analysis techniques that show promise for complementing the information in static uptake values.

Three-dimensional conformal radiotherapy by delineations on CT-based simulation in different respiratory phases for the treatment of senile patients with non-small cell lung cancer.

PubMed

Wang, Weifeng; Yuan, Feng; Wang, Guoping; Lin, Zhiren; Pan, Yanling; Chen, Longhua

2015-01-01

This study aimed to evaluate the application of three-dimensional conformal radiotherapy (3D-CRT) for elderly patients with non-small cell lung cancer (NSCLC) based on computed tomography (CT) simulations in different respiratory phases. A total of 64 patients aged >70 years old with NSCLC were treated by 3D-CRT using CT images in different respiratory phases. The gross tumor volumes (GTVs) at the end of inspiration and end of expiration were combined to obtain the total GTV, which was close to the motional range of tumors during respiration, and no additional expansion of the clinical target volume (CTAV) to planning target volume (PTV) (CTAV:PTV) was included during the recording of respiratory movements. Patients were also planned according to the classic 3D-CRT approach. Efficacy, prognostic factors, and side effects were evaluated. Compared with the classic approach, the average PTV was 18.9% lower (median: 17.3%), and the average lung volume receiving a prescribed dose for a tumor was 22.4% lower (median: 20.9%). The 1-, 2-, and 3-year survival rates were 70.6%, 54.9%, and 29.4%, respectively, with an overall tumor response rate of 79.7%. The Karnofsky performance status and N stage were independent prognostic factors, whereas age was not. Without affecting therapeutic effects, CT simulations in different respiratory phases were well-tolerated in elderly patients with NSCLC, could effectively reduce PTV, and could improve the quality of life.

Bladder filling variation during conformal radiotherapy for rectal cancer

NASA Astrophysics Data System (ADS)

Sithamparam, S.; Ahmad, R.; Sabarudin, A.; Othman, Z.; Ismail, M.

2017-05-01

Conformal radiotherapy for rectal cancer is associated with small bowel toxicity mainly diarrhea. Treating patients with a full bladder is one of the practical solutions to reduce small bowel toxicity. Previous studies on prostate and cervix cancer patients revealed that maintaining consistent bladder volume throughout radiotherapy treatment is challenging. The aim of this study was to measure bladder volume variation throughout radiotherapy treatment. This study also measured the association between bladder volume changes and diarrhea. Twenty two rectal cancer patients were recruited prospectively. Patients were planned for treatment with full bladder following departmental bladder filling protocol and the planning bladder volume was measured during CT-simulation. During radiotherapy, the bladder volume was measured weekly using cone-beam computed tomography (CBCT) and compared to planning bladder volume. Incidence and severity of diarrhea were recorded during the weekly patient review. There was a negative time trend for bladder volume throughout five weeks treatment. The mean bladder volume decreased 18 % from 123 mL (SD 54 mL) during CT-simulation to 101 mL (SD 71 mL) on the 5th week of radiotherapy, but the decrease is not statistically significant. However, there was a large variation of bladder volume within each patient during treatment. This study showed an association between changes of bladder volume and diarrhea (P = 0.045). In conclusion bladder volume reduced throughout radiotherapy treatment for conformal radiotherapy for rectal cancer and there was a large variation of bladder volume within patients.

SU-E-J-73: Extension of a Clinical OIS/EMR/R&V System to Deliver Safe and Efficient Adaptive Plan-Of-The-Day Treatments Using a Fully Customizable Plan-Library-Based Workflow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akhiat, A.; Elekta, Sunnyvale, CA; Kanis, A.P.

Purpose: To extend a clinical Record and Verify (R&V) system to enable a safe and fast workflow for Plan-of-the-Day (PotD) adaptive treatments based on patient-specific plan libraries. Methods: Plan libraries for PotD adaptive treatments contain for each patient several pre-treatment generated treatment plans. They may be generated for various patient anatomies or CTV-PTV margins. For each fraction, a Cone Beam CT scan is acquired to support the selection of the plan that best fits the patient’s anatomy-of-the-day. To date, there are no commercial R&V systems that support PotD delivery strategies. Consequently, the clinical workflow requires many manual interventions. Moreover, multiplemore » scheduled plans have a high risk of excessive dose delivery. In this work we extended a commercial R&V system (MOSAIQ) to support PotD workflows using IQ-scripting. The PotD workflow was designed after extensive risk analysis of the manual procedure, and all identified risks were incorporated as logical checks. Results: All manual PotD activities were automated. The workflow first identifies if the patient is scheduled for PotD, then performs safety checks, and continues to treatment plan selection only if no issues were found. The user selects the plan to deliver from a list of candidate plans. After plan selection, the workflow makes the treatment fields of the selected plan available for delivery by adding them to the treatment calendar. Finally, control is returned to the R&V system to commence treatment. Additional logic was added to incorporate off-line changes such as updating the plan library. After extensive testing including treatment fraction interrupts and plan-library updates during the treatment course, the workflow is running successfully in a clinical pilot, in which 35 patients have been treated since October 2014. Conclusion: We have extended a commercial R&V system for improved safety and efficiency in library-based adaptive strategies enabling a wide-spread implementation of those strategies. This work was in part funded by a research grant of Elekta AB, Stockholm, Sweden.« less

SU-F-J-113: Multi-Atlas Based Automatic Organ Segmentation for Lung Radiotherapy Planning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, J; Han, J; Ailawadi, S

Purpose: Normal organ segmentation is one time-consuming and labor-intensive step for lung radiotherapy treatment planning. The aim of this study is to evaluate the performance of a multi-atlas based segmentation approach for automatic organs at risk (OAR) delineation. Methods: Fifteen Lung stereotactic body radiation therapy patients were randomly selected. Planning CT images and OAR contours of the heart - HT, aorta - AO, vena cava - VC, pulmonary trunk - PT, and esophagus – ES were exported and used as reference and atlas sets. For automatic organ delineation for a given target CT, 1) all atlas sets were deformably warpedmore » to the target CT, 2) the deformed sets were accumulated and normalized to produce organ probability density (OPD) maps, and 3) the OPD maps were converted to contours via image thresholding. Optimal threshold for each organ was empirically determined by comparing the auto-segmented contours against their respective reference contours. The delineated results were evaluated by measuring contour similarity metrics: DICE, mean distance (MD), and true detection rate (TD), where DICE=(intersection volume/sum of two volumes) and TD = {1.0 - (false positive + false negative)/2.0}. Diffeomorphic Demons algorithm was employed for CT-CT deformable image registrations. Results: Optimal thresholds were determined to be 0.53 for HT, 0.38 for AO, 0.28 for PT, 0.43 for VC, and 0.31 for ES. The mean similarity metrics (DICE[%], MD[mm], TD[%]) were (88, 3.2, 89) for HT, (79, 3.2, 82) for AO, (75, 2.7, 77) for PT, (68, 3.4, 73) for VC, and (51,2.7, 60) for ES. Conclusion: The investigated multi-atlas based approach produced reliable segmentations for the organs with large and relatively clear boundaries (HT and AO). However, the detection of small and narrow organs with diffused boundaries (ES) were challenging. Sophisticated atlas selection and multi-atlas fusion algorithms may further improve the quality of segmentations.« less

Optimal gross tumor volume definition in lung-sparing intensity modulated radiotherapy for pleural mesothelioma: an in silico study.

PubMed

Botticella, Angela; Defraene, Gilles; Nackaerts, Kristiaan; Deroose, Christophe M; Coolen, Johan; Nafteux, Philippe; Peeters, Stephanie; Ricardi, Umberto; De Ruysscher, Dirk

2016-12-01

The gross tumor volume (GTV) definition for malignant pleural mesothelioma (MPM) is ill-defined. We therefore investigated which imaging modality is optimal: computed tomography (CT) with intravenous contrast (IVC), positron emission tomography-CT (PET/CT) or magnetic resonance imaging (MRI). Sixteen consecutive patients with untreated stage I-IV MPM were included. Patients with prior pleurodesis were excluded. CT with IVC, 18FDG-PET/CT and MRI (T2 and contrast-enhanced T1) were obtained. CT was rigidly co-registered with PET/CT and with MRI. Three sets of pleural GTVs were defined: GTV CT , GTV CT+PET/CT and GTV CT+MRI . Quantitative and qualitative evaluations of the contoured GTVs were performed. Compared to CT-based GTV definition, PET/CT identified additional tumor sites (defined as either separate nodules or greater extent of a known tumor) in 12/16 patients. Compared to either CT or PET/CT, MRI identified additional tumor sites in 15/16 patients (p = .7). The mean GTV CT , GTV CT+PET/CT and GTV CT+MRI [±standard deviation (SD)] were 630.1 cm 3 (±302.81), 640.23 cm 3 (±302.83) and 660.8 cm 3 (±290.8), respectively. Differences in mean volumes were not significant. The mean Jaccard Index was significantly lower in MRI-based contours versus all the others. As MRI identified additional pleural disease sites in the majority of patients, it may play a role in optimal target volume definition.

Dosimetric comparison between conventional and conformal radiotherapy for carcinoma cervix: Are we treating the right volumes?

PubMed Central

Goswami, Jyotirup; Patra, Niladri B.; Sarkar, Biplab; Basu, Ayan; Pal, Santanu

2013-01-01

Background and Purpose: Conventional portals, based on bony anatomy, for external beam radiotherapy for cervical cancer have been repeatedly demonstrated as inadequate. Conversely, with image-based conformal radiotherapy, better target coverage may be offset by the greater toxicities and poorer compliance associated with treating larger volumes. This study was meant to dosimetrically compare conformal and conventional radiotherapy. Materials and Methods: Five patients of carcinoma cervix underwent planning CT scan with IV contrast and targets, and organs at risk (OAR) were contoured. Two sets of plans-conventional and conformal were generated for each patient. Field sizes were recorded, and dose volume histograms of both sets of plans were generated and compared on the basis of target coverage and OAR sparing. Results: Target coverage was significantly improved with conformal plans though field sizes required were significantly larger. On the other hand, dose homogeneity was not significantly improved. Doses to the OARs (rectum, urinary bladder, and small bowel) were not significantly different across the 2 arms. Conclusion: Three-dimensional conformal radiotherapy gives significantly better target coverage, which may translate into better local control and survival. On the other hand, it also requires significantly larger field sizes though doses to the OARs are not significantly increased. PMID:24455584

Cardiac CT for myocardial ischaemia detection and characterization--comparative analysis.

PubMed

Bucher, A M; De Cecco, C N; Schoepf, U J; Wang, R; Meinel, F G; Binukrishnan, S R; Spearman, J V; Vogl, T J; Ruzsics, B

2014-11-01

The assessment of patients presenting with symptoms of myocardial ischaemia remains one of the most common and challenging clinical scenarios faced by physicians. Current imaging modalities are capable of three-dimensional, functional and anatomical views of the heart and as such offer a unique contribution to understanding and managing the pathology involved. Evidence has accumulated that visual anatomical coronary evaluation does not adequately predict haemodynamic relevance and should be complemented by physiological evaluation, highlighting the importance of functional assessment. Technical advances in CT technology over the past decade have progressively moved cardiac CT imaging into the clinical workflow. In addition to anatomical evaluation, cardiac CT is capable of providing myocardial perfusion parameters. A variety of CT techniques can be used to assess the myocardial perfusion. The single energy first-pass CT and dual energy first-pass CT allow static assessment of myocardial blood pool. Dynamic cardiac CT imaging allows quantification of myocardial perfusion through time-resolved attenuation data. CT-based myocardial perfusion imaging (MPI) is showing promising diagnostic accuracy compared with the current reference modalities. The aim of this review is to present currently available myocardial perfusion techniques with a focus on CT imaging in light of recent clinical investigations. This article provides a comprehensive overview of currently available CT approaches of static and dynamic MPI and presents the results of corresponding clinical trials.

Image guidance doses delivered during radiotherapy: Quantification, management, and reduction: Report of the AAPM Therapy Physics Committee Task Group 180.

PubMed

Ding, George X; Alaei, Parham; Curran, Bruce; Flynn, Ryan; Gossman, Michael; Mackie, T Rock; Miften, Moyed; Morin, Richard; Xu, X George; Zhu, Timothy C

2018-05-01

With radiotherapy having entered the era of image guidance, or image-guided radiation therapy (IGRT), imaging procedures are routinely performed for patient positioning and target localization. The imaging dose delivered may result in excessive dose to sensitive organs and potentially increase the chance of secondary cancers and, therefore, needs to be managed. This task group was charged with: a) providing an overview on imaging dose, including megavoltage electronic portal imaging (MV EPI), kilovoltage digital radiography (kV DR), Tomotherapy MV-CT, megavoltage cone-beam CT (MV-CBCT) and kilovoltage cone-beam CT (kV-CBCT), and b) providing general guidelines for commissioning dose calculation methods and managing imaging dose to patients. We briefly review the dose to radiotherapy (RT) patients resulting from different image guidance procedures and list typical organ doses resulting from MV and kV image acquisition procedures. We provide recommendations for managing the imaging dose, including different methods for its calculation, and techniques for reducing it. The recommended threshold beyond which imaging dose should be considered in the treatment planning process is 5% of the therapeutic target dose. Although the imaging dose resulting from current kV acquisition procedures is generally below this threshold, the ALARA principle should always be applied in practice. Medical physicists should make radiation oncologists aware of the imaging doses delivered to patients under their care. Balancing ALARA with the requirement for effective target localization requires that imaging dose be managed based on the consideration of weighing risks and benefits to the patient. © 2018 American Association of Physicists in Medicine.

Validation of a deformable image registration technique for cone beam CT-based dose verification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moteabbed, M., E-mail: mmoteabbed@partners.org; Sharp, G. C.; Wang, Y.

2015-01-15

Purpose: As radiation therapy evolves toward more adaptive techniques, image guidance plays an increasingly important role, not only in patient setup but also in monitoring the delivered dose and adapting the treatment to patient changes. This study aimed to validate a method for evaluation of delivered intensity modulated radiotherapy (IMRT) dose based on multimodal deformable image registration (DIR) for prostate treatments. Methods: A pelvic phantom was scanned with CT and cone-beam computed tomography (CBCT). Both images were digitally deformed using two realistic patient-based deformation fields. The original CT was then registered to the deformed CBCT resulting in a secondary deformedmore » CT. The registration quality was assessed as the ability of the DIR method to recover the artificially induced deformations. The primary and secondary deformed CT images as well as vector fields were compared to evaluate the efficacy of the registration method and it’s suitability to be used for dose calculation. PLASTIMATCH, a free and open source software was used for deformable image registration. A B-spline algorithm with optimized parameters was used to achieve the best registration quality. Geometric image evaluation was performed through voxel-based Hounsfield unit (HU) and vector field comparison. For dosimetric evaluation, IMRT treatment plans were created and optimized on the original CT image and recomputed on the two warped images to be compared. The dose volume histograms were compared for the warped structures that were identical in both warped images. This procedure was repeated for the phantom with full, half full, and empty bladder. Results: The results indicated mean HU differences of up to 120 between registered and ground-truth deformed CT images. However, when the CBCT intensities were calibrated using a region of interest (ROI)-based calibration curve, these differences were reduced by up to 60%. Similarly, the mean differences in average vector field lengths decreased from 10.1 to 2.5 mm when CBCT was calibrated prior to registration. The results showed no dependence on the level of bladder filling. In comparison with the dose calculated on the primary deformed CT, differences in mean dose averaged over all organs were 0.2% and 3.9% for dose calculated on the secondary deformed CT with and without CBCT calibration, respectively, and 0.5% for dose calculated directly on the calibrated CBCT, for the full-bladder scenario. Gamma analysis for the distance to agreement of 2 mm and 2% of prescribed dose indicated a pass rate of 100% for both cases involving calibrated CBCT and on average 86% without CBCT calibration. Conclusions: Using deformable registration on the planning CT images to evaluate the IMRT dose based on daily CBCTs was found feasible. The proposed method will provide an accurate dose distribution using planning CT and pretreatment CBCT data, avoiding the additional uncertainties introduced by CBCT inhomogeneity and artifacts. This is a necessary initial step toward future image-guided adaptive radiotherapy of the prostate.« less

Demons deformable registration of CT and cone-beam CT using an iterative intensity matching approach

PubMed Central

Nithiananthan, Sajendra; Schafer, Sebastian; Uneri, Ali; Mirota, Daniel J.; Stayman, J. Webster; Zbijewski, Wojciech; Brock, Kristy K.; Daly, Michael J.; Chan, Harley; Irish, Jonathan C.; Siewerdsen, Jeffrey H.

2011-01-01

Purpose: A method of intensity-based deformable registration of CT and cone-beam CT (CBCT) images is described, in which intensity correction occurs simultaneously within the iterative registration process. The method preserves the speed and simplicity of the popular Demons algorithm while providing robustness and accuracy in the presence of large mismatch between CT and CBCT voxel values (“intensity”). Methods: A variant of the Demons algorithm was developed in which an estimate of the relationship between CT and CBCT intensity values for specific materials in the image is computed at each iteration based on the set of currently overlapping voxels. This tissue-specific intensity correction is then used to estimate the registration output for that iteration and the process is repeated. The robustness of the method was tested in CBCT images of a cadaveric head exhibiting a broad range of simulated intensity variations associated with x-ray scatter, object truncation, and∕or errors in the reconstruction algorithm. The accuracy of CT-CBCT registration was also measured in six real cases, exhibiting deformations ranging from simple to complex during surgery or radiotherapy guided by a CBCT-capable C-arm or linear accelerator, respectively. Results: The iterative intensity matching approach was robust against all levels of intensity variation examined, including spatially varying errors in voxel value of a factor of 2 or more, as can be encountered in cases of high x-ray scatter. Registration accuracy without intensity matching degraded severely with increasing magnitude of intensity error and introduced image distortion. A single histogram match performed prior to registration alleviated some of these effects but was also prone to image distortion and was quantifiably less robust and accurate than the iterative approach. Within the six case registration accuracy study, iterative intensity matching Demons reduced mean TRE to (2.5±2.8) mm compared to (3.5±3.0) mm with rigid registration. Conclusions: A method was developed to iteratively correct CT-CBCT intensity disparity during Demons registration, enabling fast, intensity-based registration in CBCT-guided procedures such as surgery and radiotherapy, in which CBCT voxel values may be inaccurate. Accurate CT-CBCT registration in turn facilitates registration of multimodality preoperative image and planning data to intraoperative CBCT by way of the preoperative CT, thereby linking the intraoperative frame of reference to a wealth of preoperative information that could improve interventional guidance. PMID:21626913

Demons deformable registration of CT and cone-beam CT using an iterative intensity matching approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nithiananthan, Sajendra; Schafer, Sebastian; Uneri, Ali

2011-04-15

Purpose: A method of intensity-based deformable registration of CT and cone-beam CT (CBCT) images is described, in which intensity correction occurs simultaneously within the iterative registration process. The method preserves the speed and simplicity of the popular Demons algorithm while providing robustness and accuracy in the presence of large mismatch between CT and CBCT voxel values (''intensity''). Methods: A variant of the Demons algorithm was developed in which an estimate of the relationship between CT and CBCT intensity values for specific materials in the image is computed at each iteration based on the set of currently overlapping voxels. This tissue-specificmore » intensity correction is then used to estimate the registration output for that iteration and the process is repeated. The robustness of the method was tested in CBCT images of a cadaveric head exhibiting a broad range of simulated intensity variations associated with x-ray scatter, object truncation, and/or errors in the reconstruction algorithm. The accuracy of CT-CBCT registration was also measured in six real cases, exhibiting deformations ranging from simple to complex during surgery or radiotherapy guided by a CBCT-capable C-arm or linear accelerator, respectively. Results: The iterative intensity matching approach was robust against all levels of intensity variation examined, including spatially varying errors in voxel value of a factor of 2 or more, as can be encountered in cases of high x-ray scatter. Registration accuracy without intensity matching degraded severely with increasing magnitude of intensity error and introduced image distortion. A single histogram match performed prior to registration alleviated some of these effects but was also prone to image distortion and was quantifiably less robust and accurate than the iterative approach. Within the six case registration accuracy study, iterative intensity matching Demons reduced mean TRE to (2.5{+-}2.8) mm compared to (3.5{+-}3.0) mm with rigid registration. Conclusions: A method was developed to iteratively correct CT-CBCT intensity disparity during Demons registration, enabling fast, intensity-based registration in CBCT-guided procedures such as surgery and radiotherapy, in which CBCT voxel values may be inaccurate. Accurate CT-CBCT registration in turn facilitates registration of multimodality preoperative image and planning data to intraoperative CBCT by way of the preoperative CT, thereby linking the intraoperative frame of reference to a wealth of preoperative information that could improve interventional guidance.« less

TU-H-CAMPUS-JeP2-02: Interobserver Variability of CT, PET-CT and MRI Based Primary Tumor Delineation for Lung Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karki, K; Hugo, G; Saraiya, S

Purpose: Target delineation in lung cancer radiotherapy has, in general, large variability. MRI has so far not been investigated in detail for lung cancer delineation variability. The purpose of this study is to investigate delineation variability for lung tumors using MRI and compare it to CT alone and PET-CT based delineations. Methods: Seven physicians delineated the primary tumor volumes of nine patients for the following scenarios: (1) CT only; (2) post-contrast T1-weighted MRI registered with diffusion-weighted MRI; and (3) PET-CT fusion images. To compute interobserver variability, the median surface was generated from all observers’ contours and used as the referencemore » surface. A single physician labeled the interface types (tumor to lung, atelectasis (collapsed lung), hilum, mediastinum, or chest-wall) on the median surface. Volume variation (normalized to PET-CT volume), minimum distance (MD), and bidirectional local distance (BLD) between individual observers’ contours and the reference contour were measured. Results: CT- and MRI-based normalized volumes were 1.61±0.76 (mean±SD) and 1.38±0.44, respectively, both significantly larger than PET-CT (p<0.05, paired t-test). The overall uncertainty (root mean square of SD values over all points) of both BLD and MD measures of the observers for the interfaces were not significantly different (p>0.05, two-samples t-test) for all imaging modalities except between tumor-mediastinum and tumor-atelectasis in PET-CT. The largest mean overall uncertainty was observed for tumor-atelectasis interface, the smallest for tumor-mediastinum and tumor-lung interfaces for all modalities. The whole tumor uncertainties for both BLD and MD were not significantly different between any two modalities (p>0.05, paired t-test). Overall uncertainties for the interfaces using BLD were similar to using MD. Conclusion: Large volume variations were observed between the three imaging modalities. Contouring variability appeared to depend on the interface type. This study will be useful for understanding the delineation uncertainty for radiotherapy planning of lung cancer using different imaging modalities. Disclosures: Research agreement with Phillips Healthcare (GH and EW), National Institutes of Health Licensing agreement with Varian Medical Systems (GH and EW), research grants from the National Institute of Health (GH and EW), UpToDate royalties (EW), and none (others). Authors have no potential conflicts of interest to disclose.« less

CT image electron density quantification in regions with metal implants: implications for radiotherapy treatment planning

NASA Astrophysics Data System (ADS)

Jechel, Christopher Alexander

In radiotherapy planning, computed tomography (CT) images are used to quantify the electron density of tissues and provide spatial anatomical information. Treatment planning systems use these data to calculate the expected spatial distribution of absorbed dose in a patient. CT imaging is complicated by the presence of metal implants which cause increased image noise, produce artifacts throughout the image and can exceed the available range of CT number values within the implant, perturbing electron density estimates in the image. Furthermore, current dose calculation algorithms do not accurately model radiation transport at metal-tissue interfaces. Combined, these issues adversely affect the accuracy of dose calculations in the vicinity of metal implants. As the number of patients with orthopedic and dental implants grows, so does the need to deliver safe and effective radiotherapy treatments in the presence of implants. The Medical Physics group at the Cancer Centre of Southeastern Ontario and Queen's University has developed a Cobalt-60 CT system that is relatively insensitive to metal artifacts due to the high energy, nearly monoenergetic Cobalt-60 photon beam. Kilovoltage CT (kVCT) images, including images corrected using a commercial metal artifact reduction tool, were compared to Cobalt-60 CT images throughout the treatment planning process, from initial imaging through to dose calculation. An effective metal artifact reduction algorithm was also implemented for the Cobalt-60 CT system. Electron density maps derived from the same kVCT and Cobalt-60 CT images indicated the impact of image artifacts on estimates of photon attenuation for treatment planning applications. Measurements showed that truncation of CT number data in kVCT images produced significant mischaracterization of the electron density of metals. Dose measurements downstream of metal inserts in a water phantom were compared to dose data calculated using CT images from kVCT and Cobalt-60 systems with and without artifact correction. The superior accuracy of electron density data derived from Cobalt-60 images compared to kVCT images produced calculated dose with far better agreement with measured results. These results indicated that dose calculation errors from metal image artifacts are primarily due to misrepresentation of electron density within metals rather than artifacts surrounding the implants.

SU-E-J-208: Fast and Accurate Auto-Segmentation of Abdominal Organs at Risk for Online Adaptive Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, V; Wang, Y; Romero, A

2014-06-01

Purpose: Various studies have demonstrated that online adaptive radiotherapy by real-time re-optimization of the treatment plan can improve organs-at-risk (OARs) sparing in the abdominal region. Its clinical implementation, however, requires fast and accurate auto-segmentation of OARs in CT scans acquired just before each treatment fraction. Autosegmentation is particularly challenging in the abdominal region due to the frequently observed large deformations. We present a clinical validation of a new auto-segmentation method that uses fully automated non-rigid registration for propagating abdominal OAR contours from planning to daily treatment CT scans. Methods: OARs were manually contoured by an expert panel to obtain groundmore » truth contours for repeat CT scans (3 per patient) of 10 patients. For the non-rigid alignment, we used a new non-rigid registration method that estimates the deformation field by optimizing local normalized correlation coefficient with smoothness regularization. This field was used to propagate planning contours to repeat CTs. To quantify the performance of the auto-segmentation, we compared the propagated and ground truth contours using two widely used metrics- Dice coefficient (Dc) and Hausdorff distance (Hd). The proposed method was benchmarked against translation and rigid alignment based auto-segmentation. Results: For all organs, the auto-segmentation performed better than the baseline (translation) with an average processing time of 15 s per fraction CT. The overall improvements ranged from 2% (heart) to 32% (pancreas) in Dc, and 27% (heart) to 62% (spinal cord) in Hd. For liver, kidneys, gall bladder, stomach, spinal cord and heart, Dc above 0.85 was achieved. Duodenum and pancreas were the most challenging organs with both showing relatively larger spreads and medians of 0.79 and 2.1 mm for Dc and Hd, respectively. Conclusion: Based on the achieved accuracy and computational time we conclude that the investigated auto-segmentation method overcomes an important hurdle to the clinical implementation of online adaptive radiotherapy. Partial funding for this work was provided by Accuray Incorporated as part of a research collaboration with Erasmus MC Cancer Institute.« less

SU-C-201-02: Dosimetric Verification of SBRT with FFF-VMAT Using a 3-D Radiochromic/Optical-CT Dosimetry System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Na, Y; Black, P; Wuu, C

2016-06-15

Purpose: With an increasing use of small field size and high dose rate irradiation in the advances of radiotherapy techniques, such as stereotactic body radiotherapy (SBRT) and stereotactic radiosurgery (SRS), an in-depth quality assurance (QA) system is required. The purpose of this study is to investigate a high resolution optical CT-based 3D radiochromic dosimetry system for SBRT with intensity modulated radiotherapy (IMRT) and flattening filter free (FFF) volumetric modulated arc therapy (VMAT). Methods: Cylindrical PRESAGE radiochromic dosimeters of 10cm height and 11cm diameter were used to validate SBRT. Four external landmarks were placed on the surface of each dosimeter tomore » define the isocenter of target. SBRT plans were delivered using a Varian TrueBeam™ linear accelerator (LINAC). Three validation plans, SBRT with IMRT (6MV 600MU/min), FFF-VMAT (10MV 2400MU/min), and mixed FFF-VMAT (6MV 1400MU/min, 10MV 2400MU/min), were delivered to the PRESAGE dosimeters. Each irradiated PRESAGE dosimeter was scanned using a single laser beam optical CT scanner and reconstructed with a 1mm × 1mm high spatial resolution. The comparison of measured dose distributions of irradiated PRESAGE dosimeters to those calculated by Pinnacle{sup 3} treatment planning system (TPS) were performed with a 10% dose threshold, 3% dose difference (DD), and 3mm distance-to-agreement (DTA) Gamma criteria. Results: The average pass rates for the gamma comparisons between PRESAGE and Pinnacle{sup 3} in the transverse, sagittal, coronal planes were 94.6%, 95.9%, and 96.4% for SBRT with IMRT, FFF-VMAT, and mixed FFF-VMAT plans, respectively. A good agreement of the isodose distributions of those comparisons were shown at the isodose lines 50%, 70%, 80%, 90% and 98%. Conclusion: This study demonstrates the feasibility of the high resolution optical CT-based 3D radiochromic dosimetry system for validation of SBRT with IMRT and FFF-VMAT. This dosimetry system offers higher precision QA with 3D dose information for small beams compared to what is currently available.« less

An automatic and accurate method of full heart segmentation from CT image based on linear gradient model

NASA Astrophysics Data System (ADS)

Yang, Zili

2017-07-01

Heart segmentation is an important auxiliary method in the diagnosis of many heart diseases, such as coronary heart disease and atrial fibrillation, and in the planning of tumor radiotherapy. Most of the existing methods for full heart segmentation treat the heart as a whole part and cannot accurately extract the bottom of the heart. In this paper, we propose a new method based on linear gradient model to segment the whole heart from the CT images automatically and accurately. Twelve cases were tested in order to test this method and accurate segmentation results were achieved and identified by clinical experts. The results can provide reliable clinical support.

Rib fracture after stereotactic radiotherapy on follow-up thin-section computed tomography in 177 primary lung cancer patients

PubMed Central

2011-01-01

Background Chest wall injury after stereotactic radiotherapy (SRT) for primary lung cancer has recently been reported. However, its detailed imaging findings are not clarified. So this study aimed to fully characterize the findings on computed tomography (CT), appearance time and frequency of chest wall injury after stereotactic radiotherapy (SRT) for primary lung cancer Materials and methods A total of 177 patients who had undergone SRT were prospectively evaluated for periodical follow-up thin-section CT with special attention to chest wall injury. The time at which CT findings of chest wall injury appeared was assessed. Related clinical symptoms were also evaluated. Results Rib fracture was identified on follow-up CT in 41 patients (23.2%). Rib fractures appeared at a mean of 21.2 months after the completion of SRT (range, 4 -58 months). Chest wall edema, thinning of the cortex and osteosclerosis were findings frequently associated with, and tending to precede rib fractures. No patients with rib fracture showed tumors > 16 mm from the adjacent chest wall. Chest wall pain was seen in 18 of 177 patients (10.2%), of whom 14 patients developed rib fracture. No patients complained of Grade 3 or more symptoms. Conclusion Rib fracture is frequently seen after SRT for lung cancer on CT, and is often associated with chest wall edema, thinning of the cortex and osteosclerosis. However, related chest wall pain is less frequent and is generally mild if present. PMID:21995807

Organ doses can be estimated from the computed tomography (CT) dose index for cone-beam CT on radiotherapy equipment.

PubMed

Martin, Colin J; Abuhaimed, Abdullah; Sankaralingam, Marimuthu; Metwaly, Mohamed; Gentle, David J

2016-06-01

Cone beam computed tomography (CBCT) systems are fitted to radiotherapy linear accelerators and used for patient positioning prior to treatment by image guided radiotherapy (IGRT). Radiotherapists' and radiographers' knowledge of doses to organs from CBCT imaging is limited. The weighted CT dose index for a reference beam of width 20 mm (CTDIw,ref) is displayed on Varian CBCT imaging equipment known as an On-Board Imager (OBI) linked to the Truebeam linear accelerator. This has the potential to provide an indication of organ doses. This knowledge would be helpful for guidance of radiotherapy clinicians preparing treatments. Monte Carlo simulations of imaging protocols for head, thorax and pelvic scans have been performed using EGSnrc/BEAMnrc, EGSnrc/DOSXYZnrc, and ICRP reference computational male and female phantoms to derive the mean absorbed doses to organs and tissues, which have been compared with values for the CTDIw,ref displayed on the CBCT scanner console. Substantial variations in dose were observed between male and female phantoms. Nevertheless, the CTDIw,ref gave doses within  ±21% for the stomach and liver in thorax scans and 2  ×  CTDIw,ref can be used as a measure of doses to breast, lung and oesophagus. The CTDIw,ref could provide indications of doses to the brain for head scans, and the colon for pelvic scans. It is proposed that knowledge of the link between CTDIw for CBCT should be promoted and included in the training of radiotherapy staff.

Prostate segmentation by sparse representation based classification

PubMed Central

Gao, Yaozong; Liao, Shu; Shen, Dinggang

2012-01-01

Purpose: The segmentation of prostate in CT images is of essential importance to external beam radiotherapy, which is one of the major treatments for prostate cancer nowadays. During the radiotherapy, the prostate is radiated by high-energy x rays from different directions. In order to maximize the dose to the cancer and minimize the dose to the surrounding healthy tissues (e.g., bladder and rectum), the prostate in the new treatment image needs to be accurately localized. Therefore, the effectiveness and efficiency of external beam radiotherapy highly depend on the accurate localization of the prostate. However, due to the low contrast of the prostate with its surrounding tissues (e.g., bladder), the unpredicted prostate motion, and the large appearance variations across different treatment days, it is challenging to segment the prostate in CT images. In this paper, the authors present a novel classification based segmentation method to address these problems. Methods: To segment the prostate, the proposed method first uses sparse representation based classification (SRC) to enhance the prostate in CT images by pixel-wise classification, in order to overcome the limitation of poor contrast of the prostate images. Then, based on the classification results, previous segmented prostates of the same patient are used as patient-specific atlases to align onto the current treatment image and the majority voting strategy is finally adopted to segment the prostate. In order to address the limitations of the traditional SRC in pixel-wise classification, especially for the purpose of segmentation, the authors extend SRC from the following four aspects: (1) A discriminant subdictionary learning method is proposed to learn a discriminant and compact representation of training samples for each class so that the discriminant power of SRC can be increased and also SRC can be applied to the large-scale pixel-wise classification. (2) The L1 regularized sparse coding is replaced by the elastic net in order to obtain a smooth and clear prostate boundary in the classification result. (3) Residue-based linear regression is incorporated to improve the classification performance and to extend SRC from hard classification to soft classification. (4) Iterative SRC is proposed by using context information to iteratively refine the classification results. Results: The proposed method has been comprehensively evaluated on a dataset consisting of 330 CT images from 24 patients. The effectiveness of the extended SRC has been validated by comparing it with the traditional SRC based on the proposed four extensions. The experimental results show that our extended SRC can obtain not only more accurate classification results but also smoother and clearer prostate boundary than the traditional SRC. Besides, the comparison with other five state-of-the-art prostate segmentation methods indicates that our method can achieve better performance than other methods under comparison. Conclusions: The authors have proposed a novel prostate segmentation method based on the sparse representation based classification, which can achieve considerably accurate segmentation results in CT prostate segmentation. PMID:23039673

Prostate segmentation by sparse representation based classification.

PubMed

Gao, Yaozong; Liao, Shu; Shen, Dinggang

2012-10-01

The segmentation of prostate in CT images is of essential importance to external beam radiotherapy, which is one of the major treatments for prostate cancer nowadays. During the radiotherapy, the prostate is radiated by high-energy x rays from different directions. In order to maximize the dose to the cancer and minimize the dose to the surrounding healthy tissues (e.g., bladder and rectum), the prostate in the new treatment image needs to be accurately localized. Therefore, the effectiveness and efficiency of external beam radiotherapy highly depend on the accurate localization of the prostate. However, due to the low contrast of the prostate with its surrounding tissues (e.g., bladder), the unpredicted prostate motion, and the large appearance variations across different treatment days, it is challenging to segment the prostate in CT images. In this paper, the authors present a novel classification based segmentation method to address these problems. To segment the prostate, the proposed method first uses sparse representation based classification (SRC) to enhance the prostate in CT images by pixel-wise classification, in order to overcome the limitation of poor contrast of the prostate images. Then, based on the classification results, previous segmented prostates of the same patient are used as patient-specific atlases to align onto the current treatment image and the majority voting strategy is finally adopted to segment the prostate. In order to address the limitations of the traditional SRC in pixel-wise classification, especially for the purpose of segmentation, the authors extend SRC from the following four aspects: (1) A discriminant subdictionary learning method is proposed to learn a discriminant and compact representation of training samples for each class so that the discriminant power of SRC can be increased and also SRC can be applied to the large-scale pixel-wise classification. (2) The L1 regularized sparse coding is replaced by the elastic net in order to obtain a smooth and clear prostate boundary in the classification result. (3) Residue-based linear regression is incorporated to improve the classification performance and to extend SRC from hard classification to soft classification. (4) Iterative SRC is proposed by using context information to iteratively refine the classification results. The proposed method has been comprehensively evaluated on a dataset consisting of 330 CT images from 24 patients. The effectiveness of the extended SRC has been validated by comparing it with the traditional SRC based on the proposed four extensions. The experimental results show that our extended SRC can obtain not only more accurate classification results but also smoother and clearer prostate boundary than the traditional SRC. Besides, the comparison with other five state-of-the-art prostate segmentation methods indicates that our method can achieve better performance than other methods under comparison. The authors have proposed a novel prostate segmentation method based on the sparse representation based classification, which can achieve considerably accurate segmentation results in CT prostate segmentation.

Planning the Breast Boost: Comparison of Three Techniques and Evolution of Tumor Bed During Treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hepel, Jaroslaw T.; Department of Radiation Oncology, Brown University, Rhode Island Hospital, Providence, RI; Evans, Suzanne B.

2009-06-01

Purpose: To evaluate the accuracy of two clinical techniques for electron boost planning compared with computed tomography (CT)-based planning. Additionally, we evaluated the tumor bed characteristics at whole breast planning and boost planning. Methods and Materials: A total of 30 women underwent tumor bed boost planning within 2 weeks of completing whole breast radiotherapy using three planning techniques: scar-based planning, palpation/clinical-based planning, and CT-based planning. The plans were analyzed for dosimetric coverage of the CT-delineated tumor bed. The cavity visualization score was used to define the CT-delineated tumor bed as well or poorly defined. Results: Scar-based planning resulted in inferiormore » tumor bed coverage compared with CT-based planning, with the minimal dose received by 90% of the target volume >90% in 53% and a geographic miss in 53%. The results of palpation/clinical-based planning were significantly better: 87% and 10% for the minimal dose received by 90% of the target volume >90% and geographic miss, respectively. Of the 30 tumor beds, 16 were poorly defined by the cavity visualization score. Of these 16, 8 were well demarcated by the surgical clips. The evaluation of the 22 well-defined tumor beds revealed similar results. A comparison of the tumor bed volume from the initial planning CT scan to the boost planning CT scan revealed a decrease in size in 77% of cases. The mean decrease in volume was 52%. Conclusion: The results of our study have shown that CT-based planning allows for optimal tumor bed coverage compared with clinical and scar-based approaches. However, in the setting of a poorly visualized cavity on CT without surgical clips, palpation/clinical-based planning can help delineate the appropriate target volumes and is superior to scar-based planning. CT simulation at boost planning could allow for a reduction in the boost volumes.« less

Biological Image-Guided Radiotherapy in Rectal Cancer: Challenges and Pitfalls

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roels, Sarah; Slagmolen, Pieter; Nuyts, Johan

2009-11-01

Purpose: To investigate the feasibility of integrating multiple imaging modalities for image-guided radiotherapy in rectal cancer. Patients and Methods: Magnetic resonance imaging (MRI) and fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) were performed before, during, and after preoperative chemoradiotherapy (CRT) in patients with resectable rectal cancer. The FDG-PET signals were segmented with an adaptive threshold-based and a gradient-based method. Magnetic resonance tumor volumes (TVs) were manually delineated. A nonrigid registration algorithm was applied to register the images, and mismatch analyses were carried out between MR and FDG-PET TVs and between TVs over time. Tumor volumes delineated on the images after CRTmore » were compared with the pathologic TV. Results: Forty-five FDG-PET/CT and 45 MR images were analyzed from 15 patients. The mean MRI and FDG-PET TVs showed a tendency to shrink during and after CRT. In general, MRI showed larger TVs than FDG-PET. There was an approximately 50% mismatch between the FDG-PET TV and the MRI TV at baseline and during CRT. Sixty-one percent of the FDG-PET TV and 76% of the MRI TV obtained after 10 fractions of CRT remained inside the corresponding baseline TV. On MRI, residual tumor was still suspected in all 6 patients with a pathologic complete response, whereas FDG-PET showed a metabolic complete response in 3 of them. The FDG-PET TVs delineated with the gradient-based method matched closest with pathologic findings. Conclusions: Integration of MRI and FDG-PET into radiotherapy seems feasible. Gradient-based segmentation is recommended for FDG-PET. Spatial variance between MRI and FDG-PET TVs should be taken into account for target definition.« less

A hybrid approach for fusing 4D-MRI temporal information with 3D-CT for the study of lung and lung tumor motion.

PubMed

Yang, Y X; Teo, S-K; Van Reeth, E; Tan, C H; Tham, I W K; Poh, C L

2015-08-01

Accurate visualization of lung motion is important in many clinical applications, such as radiotherapy of lung cancer. Advancement in imaging modalities [e.g., computed tomography (CT) and MRI] has allowed dynamic imaging of lung and lung tumor motion. However, each imaging modality has its advantages and disadvantages. The study presented in this paper aims at generating synthetic 4D-CT dataset for lung cancer patients by combining both continuous three-dimensional (3D) motion captured by 4D-MRI and the high spatial resolution captured by CT using the authors' proposed approach. A novel hybrid approach based on deformable image registration (DIR) and finite element method simulation was developed to fuse a static 3D-CT volume (acquired under breath-hold) and the 3D motion information extracted from 4D-MRI dataset, creating a synthetic 4D-CT dataset. The study focuses on imaging of lung and lung tumor. Comparing the synthetic 4D-CT dataset with the acquired 4D-CT dataset of six lung cancer patients based on 420 landmarks, accurate results (average error <2 mm) were achieved using the authors' proposed approach. Their hybrid approach achieved a 40% error reduction (based on landmarks assessment) over using only DIR techniques. The synthetic 4D-CT dataset generated has high spatial resolution, has excellent lung details, and is able to show movement of lung and lung tumor over multiple breathing cycles.

Collision prediction software for radiotherapy treatments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Padilla, Laura; Pearson, Erik A.; Pelizzari, Charles A., E-mail: c-pelizzari@uchicago.edu

2015-11-15

Purpose: This work presents a method of collision predictions for external beam radiotherapy using surface imaging. The present methodology focuses on collision prediction during treatment simulation to evaluate the clearance of a patient’s treatment position and allow for its modification if necessary. Methods: A Kinect camera (Microsoft, Redmond, WA) is used to scan the patient and immobilization devices in the treatment position at the simulator. The surface is reconstructed using the SKANECT software (Occipital, Inc., San Francisco, CA). The treatment isocenter is marked using simulated orthogonal lasers projected on the surface scan. The point cloud of this surface is thenmore » shifted to isocenter and converted from Cartesian to cylindrical coordinates. A slab models the treatment couch. A cylinder with a radius equal to the normal distance from isocenter to the collimator plate, and a height defined by the collimator diameter is used to estimate collisions. Points within the cylinder clear through a full gantry rotation with the treatment couch at 0° , while points outside of it collide. The angles of collision are reported. This methodology was experimentally verified using a mannequin positioned in an alpha cradle with both arms up. A planning CT scan of the mannequin was performed, two isocenters were marked in PINNACLE, and this information was exported to AlignRT (VisionRT, London, UK)—a surface imaging system for patient positioning. This was used to ensure accurate positioning of the mannequin in the treatment room, when available. Collision calculations were performed for the two treatment isocenters and the results compared to the collisions detected the room. The accuracy of the Kinect-Skanect surface was evaluated by comparing it to the external surface of the planning CT scan. Results: Experimental verification results showed that the predicted angles of collision matched those recorded in the room within 0.5°, in most cases (largest deviation −1.2°). The accuracy study for the Kinect-Skanect surface showed an average discrepancy between the CT external contour and the surface scan of 2.2 mm. Conclusions: This methodology provides fast and reliable collision predictions using surface imaging. The use of the Kinect-Skanect system allows for a comprehensive modeling of the patient topography including all the relevant anatomy and immobilization devices that may lead to collisions. The use of this tool at the treatment simulation stage may allow therapists to evaluate the clearance of a patient’s treatment position and optimize it before the planning CT scan is performed. This can allow for safer treatments for the patients due to better collision predictions and improved clinical workflow by minimizing replanning and resimulations due to unforeseen clearance issues.« less

Automatic segmentation and centroid detection of skin sensors for lung interventions

NASA Astrophysics Data System (ADS)

Lu, Kongkuo; Xu, Sheng; Xue, Zhong; Wong, Stephen T.

2012-02-01

Electromagnetic (EM) tracking has been recognized as a valuable tool for locating the interventional devices in procedures such as lung and liver biopsy or ablation. The advantage of this technology is its real-time connection to the 3D volumetric roadmap, i.e. CT, of a patient's anatomy while the intervention is performed. EM-based guidance requires tracking of the tip of the interventional device, transforming the location of the device onto pre-operative CT images, and superimposing the device in the 3D images to assist physicians to complete the procedure more effectively. A key requirement of this data integration is to find automatically the mapping between EM and CT coordinate systems. Thus, skin fiducial sensors are attached to patients before acquiring the pre-operative CTs. Then, those sensors can be recognized in both CT and EM coordinate systems and used calculate the transformation matrix. In this paper, to enable the EM-based navigation workflow and reduce procedural preparation time, an automatic fiducial detection method is proposed to obtain the centroids of the sensors from the pre-operative CT. The approach has been applied to 13 rabbit datasets derived from an animal study and eight human images from an observation study. The numerical results show that it is a reliable and efficient method for use in EM-guided application.

PET/CT (and CT) instrumentation, image reconstruction and data transfer for radiotherapy planning.

PubMed

Sattler, Bernhard; Lee, John A; Lonsdale, Markus; Coche, Emmanuel

2010-09-01

The positron emission tomography in combination with CT in hybrid, cross-modality imaging systems (PET/CT) gains more and more importance as a part of the treatment-planning procedure in radiotherapy. Positron emission tomography (PET), as a integral part of nuclear medicine imaging and non-invasive imaging technique, offers the visualization and quantification of pre-selected tracer metabolism. In combination with the structural information from CT, this molecular imaging technique has great potential to support and improve the outcome of the treatment-planning procedure prior to radiotherapy. By the choice of the PET-Tracer, a variety of different metabolic processes can be visualized. First and foremost, this is the glucose metabolism of a tissue as well as for instance hypoxia or cell proliferation. This paper comprises the system characteristics of hybrid PET/CT systems. Acquisition and processing protocols are described in general and modifications to cope with the special needs in radiooncology. This starts with the different position of the patient on a special table top, continues with the use of the same fixation material as used for positioning of the patient in radiooncology while simulation and irradiation and leads to special processing protocols that include the delineation of the volumes that are subject to treatment planning and irradiation (PTV, GTV, CTV, etc.). General CT acquisition and processing parameters as well as the use of contrast enhancement of the CT are described. The possible risks and pitfalls the investigator could face during the hybrid-imaging procedure are explained and listed. The interdisciplinary use of different imaging modalities implies a increase of the volume of data created. These data need to be stored and communicated fast, safe and correct. Therefore, the DICOM-Standard provides objects and classes for this purpose (DICOM RT). Furthermore, the standard DICOM objects and classes for nuclear medicine (NM, PT) and computed tomography (CT) are used to communicate the actual image data created by the modalities. Care must be taken for data security, especially when transferring data across the (network-) borders of different hospitals. Overall, the most important precondition for successful integration of functional imaging in RT treatment planning is the goal orientated as well as close and thorough communication between nuclear medicine and radiotherapy departments on all levels of interaction (personnel, imaging protocols, GTV delineation, and selection of the data transfer method). Copyright 2010 European Society for Therapeutic Radiology and Oncology and European Association of Nuclear Medicine. Published by Elsevier Ireland Ltd.. All rights reserved.

Patient positioning in head and neck cancer : Setup variations and safety margins in helical tomotherapy.

PubMed

Leitzen, Christina; Wilhelm-Buchstab, Timo; Müdder, Thomas; Heimann, Martina; Koch, David; Schmeel, Christopher; Simon, Birgit; Stumpf, Sabina; Vornholt, Susanne; Garbe, Stephan; Röhner, Fred; Schoroth, Felix; Schild, Hans Heinz; Schüller, Heinrich

2018-05-01

To evaluate the interfractional variations of patient positioning during intensity-modulated radiotherapy (IMRT) with helical tomotherapy in head and neck cancer and to calculate the required safety margins (sm) for bony landmarks resulting from the necessary table adjustments. In all, 15 patients with head and neck cancer were irradiated using the Hi-Art II tomotherapy system between April and September 2016. Before therapy sessions, patient position was frequently checked by megavolt computed tomography (MV-CT). Necessary table adjustments (ta) in the right-left (rl), superior-inferior (si) and anterior-posterior (ap) directions were recorded for four anatomical points: second, fourth and sixth cervical vertebral body (CVB), anterior nasal spine (ANS). Based upon these data sm were calculated for non-image-guided radiotherapy, image-guided radiotherapy (IGRT) and image guidance limited to a shortened area (CVB 2). Based upon planning CT the actual treatment required ta from -0.05 ± 1.31 mm for CVB 2 (ap) up to 2.63 ± 2.39 mm for ANS (rl). Considering the performed ta resulting from image control (MV-CT) we detected remaining ta from -0.10 ± 1.09 mm for CVB 4 (rl) up to 1.97 ± 1.64 mm for ANS (si). After theoretical adjustment of patients position to CVB 2 the resulting ta ranged from -0.11 ± 2.44 mm for CVB6 (ap) to 2.37 ± 2.17 mm for ANS (si). These data imply safety margins: uncorrected patient position: 3.63-9.95 mm, corrected positioning based upon the whole target volume (IGRT): 1.85-6.63 mm, corrected positioning based upon CVB 2 (IGRT): 3.13-6.66 mm. The calculated safety margins differ between anatomic regions. Repetitive and frequent image control of patient positioning is necessary that, however, possibly may be focussed on a limited region.

A new fiducial marker for Image-guided radiotherapy of prostate cancer: clinical experience.

PubMed

Carl, Jesper; Nielsen, Jane; Holmberg, Mats; Højkjaer Larsen, Erik; Fabrin, Knud; Fisker, Rune V

2008-01-01

A new fiducial marker for image guided radiotherapy (IGRT) based on a removable prostate stent made of Ni Ti has been developed during two previous clinical feasibility studies. The marker is currently being evaluated for IGRT treatment in a third clinical study. The new marker is used to co-register MR and planning CT scans with high accuracy in the region around the prostate. The co-registered MR-CT volumes are used for delineation of GTV before planning. In each treatment session the IGRT system is used to position the patient before treatment. The IGRT system use a stereo pair of kV images matched to corresponding Digital Reconstructed Radiograms (DRR) from the planning CT scan. The match is done using mutual gray scale information. The pair of DRR's for positioning is created in the IGRT system with a threshold in the Look Up Table (LUT). The resulting match provides the necessary shift in couch coordinates to position the stent with an accuracy of 1-2 mm within the planned position. At the present time 39 patients have received the new marker. Of the 39 one has migrated to the bladder. Deviations of more than 5 mm between CTV outlined on CT and MR are seen in several cases and in anterior-posterior (AP), left-right (LR) and cranial-caudal (CC) directions. Intra-fraction translation movements up to +/- 3 mm are seen as well. As the stent is also clearly visible on images taken with high voltage x-rays using electronic portal images devices (EPID), the positioning has been verified independently of the IGRT system. The preliminary result of an on going clinical study of a Ni Ti prostate stent, potentially a new fiducial marker for image guided radiotherapy, looks promising. The risk of migration appears to be much lower compared to previous designs.

SU-E-J-120: Comparing 4D CT Computed Ventilation to Lung Function Measured with Hyperpolarized Xenon-129 MRI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neal, B; Chen, Q

2015-06-15

Purpose: To correlate ventilation parameters computed from 4D CT to ventilation, profusion, and gas exchange measured with hyperpolarized Xenon-129 MRI for a set of lung cancer patients. Methods: Hyperpolarized Xe-129 MRI lung scans were acquired for lung cancer patients, before and after radiation therapy, measuring ventilation, perfusion, and gas exchange. In the standard clinical workflow, these patients also received 4D CT scans before treatment. Ventilation was computed from 4D CT using deformable image registration (DIR). All phases of the 4D CT scan were registered using a B-spline deformable registration. Ventilation at the voxel level was then computed for each phasemore » based on a Jacobian volume expansion metric, yielding phase sorted ventilation images. Ventilation based upon 4D CT and Xe-129 MRI were co-registered, allowing qualitative visual comparison and qualitative comparison via the Pearson correlation coefficient. Results: Analysis shows a weak correlation between hyperpolarized Xe-129 MRI and 4D CT DIR ventilation, with a Pearson correlation coefficient of 0.17 to 0.22. Further work will refine the DIR parameters to optimize the correlation. The weak correlation could be due to the limitations of 4D CT, registration algorithms, or the Xe-129 MRI imaging. Continued development will refine parameters to optimize correlation. Conclusion: Current analysis yields a minimal correlation between 4D CT DIR and Xe-129 MRI ventilation. Funding provided by the 2014 George Amorino Pilot Grant in Radiation Oncology at the University of Virginia.« less

A tri-modality image fusion method for target delineation of brain tumors in radiotherapy.

PubMed

Guo, Lu; Shen, Shuming; Harris, Eleanor; Wang, Zheng; Jiang, Wei; Guo, Yu; Feng, Yuanming

2014-01-01

To develop a tri-modality image fusion method for better target delineation in image-guided radiotherapy for patients with brain tumors. A new method of tri-modality image fusion was developed, which can fuse and display all image sets in one panel and one operation. And a feasibility study in gross tumor volume (GTV) delineation using data from three patients with brain tumors was conducted, which included images of simulation CT, MRI, and 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) examinations before radiotherapy. Tri-modality image fusion was implemented after image registrations of CT+PET and CT+MRI, and the transparency weight of each modality could be adjusted and set by users. Three radiation oncologists delineated GTVs for all patients using dual-modality (MRI/CT) and tri-modality (MRI/CT/PET) image fusion respectively. Inter-observer variation was assessed by the coefficient of variation (COV), the average distance between surface and centroid (ADSC), and the local standard deviation (SDlocal). Analysis of COV was also performed to evaluate intra-observer volume variation. The inter-observer variation analysis showed that, the mean COV was 0.14(± 0.09) and 0.07(± 0.01) for dual-modality and tri-modality respectively; the standard deviation of ADSC was significantly reduced (p<0.05) with tri-modality; SDlocal averaged over median GTV surface was reduced in patient 2 (from 0.57 cm to 0.39 cm) and patient 3 (from 0.42 cm to 0.36 cm) with the new method. The intra-observer volume variation was also significantly reduced (p = 0.00) with the tri-modality method as compared with using the dual-modality method. With the new tri-modality image fusion method smaller inter- and intra-observer variation in GTV definition for the brain tumors can be achieved, which improves the consistency and accuracy for target delineation in individualized radiotherapy.

SU-E-J-39: Dosimetric Benefit of Implanted Marker-Based CBCT Setup for Definitive Prostatic Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhen, H; Wu, Z; Bluemenfeld, P

Purpose Daily setup for definitive prostatic radiotherapy is challenged by suboptimal visibility of the prostate boundary and daily variation of rectum shape and position. For patients with improved bowel preparation, we conducted a dosimetric comparison between prostate implanted marker (IM)-based daily setup and anterior rectal wall (ARW)-based setup, with the hypothesis that the former leads to adequate target coverage with better rectal sparing. Methods Five IMRT/VMAT prostate cases with implanted markers were selected for analysis. Daily CBCT showed improvement of the rectal volume compared to planning CT. For each patient, the prostate and rectum were contoured on three CBCT imagesmore » (fraction 5/15/25) with subsequent physician review. The CBCTs were then registered to a planning CT using IM-based registration. The deviation of ARW positions from planning CT to CBCT were analyzed at various sup-inf levels (−1.8 cm to 1.8 cm from level of prostate center). To estimate the potential dosimetric impact from ARW-based setup, the treatment plans were recalculated using A-P shifts ranging from −1mm to +6mm. Clinically important rectum DVH values including Dmax, D3cc and Dmean were computed. Results For the studied patients, we observed on average 32% rectum volume reduction from planning CT to CBCT. As a Results, the ARW on average shifts posteriorly by −1mm to +5mm, depending on the sup-inf level of observation, with larger shifts observed at more superior levels. Recalculation shows that when ARW shifts 1mm posteriorly, ARW-based CBCT setup leads to a 1.0%, 4.2%, and 3.2% increase in rectum Dmax, D3cc, and Dmean, respectively, compared to IM-based setup. The dosimetric deviations increase to 4.7%, 25.8% and 24.7% when ARW shifts 6mm posteriorly. No significant prostate-only dose difference was observed. Conclusion For patients with improved bowel preparation, IM-based CBCT setup leads to accurate prostate coverage along with significantly lower rectal dose, compared to ARW-based setup.« less

Radiomics based targeted radiotherapy planning (Rad-TRaP): a computational framework for prostate cancer treatment planning with MRI.

PubMed

Shiradkar, Rakesh; Podder, Tarun K; Algohary, Ahmad; Viswanath, Satish; Ellis, Rodney J; Madabhushi, Anant

2016-11-10

Radiomics or computer - extracted texture features have been shown to achieve superior performance than multiparametric MRI (mpMRI) signal intensities alone in targeting prostate cancer (PCa) lesions. Radiomics along with deformable co-registration tools can be used to develop a framework to generate targeted focal radiotherapy treatment plans. The Rad-TRaP framework comprises three distinct modules. Firstly, a module for radiomics based detection of PCa lesions on mpMRI via a feature enabled machine learning classifier. The second module comprises a multi-modal deformable co-registration scheme to map tissue, organ, and delineated target volumes from MRI onto CT. Finally, the third module involves generation of a radiomics based dose plan on MRI for brachytherapy and on CT for EBRT using the target delineations transferred from the MRI to the CT. Rad-TRaP framework was evaluated using a retrospective cohort of 23 patient studies from two different institutions. 11 patients from the first institution were used to train a radiomics classifier, which was used to detect tumor regions in 12 patients from the second institution. The ground truth cancer delineations for training the machine learning classifier were made by an experienced radiation oncologist using mpMRI, knowledge of biopsy location and radiology reports. The detected tumor regions were used to generate treatment plans for brachytherapy using mpMRI, and tumor regions mapped from MRI to CT to generate corresponding treatment plans for EBRT. For each of EBRT and brachytherapy, 3 dose plans were generated - whole gland homogeneous ([Formula: see text]) which is the current clinical standard, radiomics based focal ([Formula: see text]), and whole gland with a radiomics based focal boost ([Formula: see text]). Comparison of [Formula: see text] against conventional [Formula: see text] revealed that targeted focal brachytherapy would result in a marked reduction in dosage to the OARs while ensuring that the prescribed dose is delivered to the lesions. [Formula: see text] resulted in only a marginal increase in dosage to the OARs compared to [Formula: see text]. A similar trend was observed in case of EBRT with [Formula: see text] and [Formula: see text] compared to [Formula: see text]. A radiotherapy planning framework to generate targeted focal treatment plans has been presented. The focal treatment plans generated using the framework showed reduction in dosage to the organs at risk and a boosted dose delivered to the cancerous lesions.

Cancer cervix: Establishing an evidence-based strategy, an experience of a tertiary care centre in India.

PubMed

Shrivastava, Shyam Kishore; Lewis, Shirley; Sastri, Supriya Chopra; Lavanya, G; Mahantshetty, Umesh; Engineer, Reena

2018-01-12

Carcinoma cervix is a common cancer among Indian women. Evidence based management is essential for best practice in treatment of carcinoma cervix for its effective control. The current imaging system like CT, MRI and PET CT scans have contributed in identifying the patients for optimal treatment and delivering treatment accurately. For stages IB2 to IV, concurrent chemoradiation is advocated with improvement in overall survival proven with randomized trials. Brachytherapy is an integral part in the radiation treatment. Imaged-guided brachytherapy using MRI is desirable, however less expensive imaging modalities such as CT and ultrasonography has been evaluated. In special situation such as for HIV positive patients and patients with neuroendocrine tumors have role of radiotherapy. For further improvement in control of cancer, it is required to integrate basic research to answer clinically relevant questions. Copyright © 2018 Elsevier Inc. All rights reserved.

Active contour based segmentation of resected livers in CT images

NASA Astrophysics Data System (ADS)

Oelmann, Simon; Oyarzun Laura, Cristina; Drechsler, Klaus; Wesarg, Stefan

2015-03-01

The majority of state of the art segmentation algorithms are able to give proper results in healthy organs but not in pathological ones. However, many clinical applications require an accurate segmentation of pathological organs. The determination of the target boundaries for radiotherapy or liver volumetry calculations are examples of this. Volumetry measurements are of special interest after tumor resection for follow up of liver regrow. The segmentation of resected livers presents additional challenges that were not addressed by state of the art algorithms. This paper presents a snakes based algorithm specially developed for the segmentation of resected livers. The algorithm is enhanced with a novel dynamic smoothing technique that allows the active contour to propagate with different speeds depending on the intensities visible in its neighborhood. The algorithm is evaluated in 6 clinical CT images as well as 18 artificial datasets generated from additional clinical CT images.

Usefulness of image morphing techniques in cancer treatment by conformal radiotherapy

NASA Astrophysics Data System (ADS)

Atoui, Hussein; Sarrut, David; Miguet, Serge

2004-05-01

Conformal radiotherapy is a cancer treatment technique, that targets high-energy X-rays to tumors with minimal exposure to surrounding healthy tissues. Irradiation ballistics is calculated based on an initial 3D Computerized Tomography (CT) scan. At every treatment session, the random positioning of the patient, compared to the reference position defined by the initial 3D CT scan, can generate treatment inaccuracies. Positioning errors potentially predispose to dangerous exposure to healthy tissues as well as insufficient irradiation to the tumor. A proposed solution would be the use of portal images generated by Electronic Portal Imaging Devices (EPID). Portal images (PI) allow a comparison with reference images retained by physicians, namely Digitally Reconstructed Radiographs (DRRs). At present, physicians must estimate patient positional errors by visual inspection. However, this may be inaccurate and consumes time. The automation of this task has been the subject of many researches. Unfortunately, the intensive use of DRRs and the high computing time required have prevented real time implementation. We are currently investigating a new method for DRR generation that calculates intermediate DRRs by 2D deformation of previously computed DRRs. We approach this investigation with the use of a morphing-based technique named mesh warping.

Dosimetric impact of different CT datasets for stereotactic treatment planning using 3D conformal radiotherapy or volumetric modulated arc therapy.

PubMed

Oechsner, Markus; Odersky, Leonhard; Berndt, Johannes; Combs, Stephanie Elisabeth; Wilkens, Jan Jakob; Duma, Marciana Nona

2015-12-01

The purpose of this study was to assess the impact on dose to the planning target volume (PTV) and organs at risk (OAR) by using four differently generated CT datasets for dose calculation in stereotactic body radiotherapy (SBRT) of lung and liver tumors. Additionally, dose differences between 3D conformal radiotherapy and volumetric modulated arc therapy (VMAT) plans calculated on these CT datasets were determined. Twenty SBRT patients, ten lung cases and ten liver cases, were retrospectively selected for this study. Treatment plans were optimized on average intensity projection (AIP) CTs using 3D conformal radiotherapy (3D-CRT) and volumetric modulated arc therapy (VMAT). Afterwards, the plans were copied to the planning CTs (PCT), maximum intensity projection (MIP) and mid-ventilation (MidV) CT datasets and dose was recalculated keeping all beam parameters and monitor units unchanged. Ipsilateral lung and liver volumes and dosimetric parameters for PTV (Dmean, D2, D98, D95), ipsilateral lung and liver (Dmean, V30, V20, V10) were determined and statistically analysed using Wilcoxon test. Significant but small mean differences were found for PTV dose between the CTs (lung SBRT: ≤2.5 %; liver SBRT: ≤1.6 %). MIPs achieved the smallest lung and the largest liver volumes. OAR mean doses in MIP plans were distinctly smaller than in the other CT datasets. Furthermore, overlapping of tumors with the diaphragm results in underestimated ipsilateral lung dose in MIP plans. Best agreement was found between AIP and MidV (lung SBRT). Overall, differences in liver SBRT were smaller than in lung SBRT and VMAT plans achieved slightly smaller differences than 3D-CRT plans. Only small differences were found for PTV parameters between the four CT datasets. Larger differences occurred for the doses to organs at risk (ipsilateral lung, liver) especially for MIP plans. No relevant differences were observed between 3D-CRT or VMAT plans. MIP CTs are not appropriate for OAR dose assessment. PCT, AIP and MidV resulted in similar doses. If a 4DCT is acquired PCT can be omitted using AIP or MidV for treatment planning.

Role of fluorine-18 fluorodeoxyglucose PET/CT in head and neck oncology: the point of view of the radiation oncologist

PubMed Central

Navarro, Arturo; del Hoyo, Olga; Gomez-Iturriaga, Alfonso; Alongi, Filippo; Medina, Jose A; Elicin, Olgun; Skanjeti, Andrea; Giammarile, Francesco; Bilbao, Pedro; Casquero, Francisco; de Bari, Berardino; Dal Pra, Alan

2016-01-01

Squamous cell carcinoma is the most common malignant tumour of the head and neck. The initial TNM staging, the evaluation of the tumour response during treatment, and the long-term surveillance are crucial moments in the approach to head and neck squamous cell carcinoma (HNSCC). Thus, at each of these moments, the choice of the best diagnostic tool providing the more precise and larger information is crucial. Positron emission tomography with fluorine-18 fludeoxyglucose integrated with CT (18F-FDG-PET/CT) rapidly gained clinical acceptance, and it has become an important imaging tool in routine clinical oncology. However, controversial data are currently available, for example, on the role of 18F-FDG-PET/CT imaging during radiotherapy planning, the prognostic value or its real clinical impact on treatment decisions. In this article, the role of 18F-FDG-PET/CT imaging in HNSCC during pre-treatment staging, radiotherapy planning, treatment response assessment, prognosis and follow-up is reviewed focusing on current evidence and controversial issues. A proposal on how to integrate 18F-FDG-PET/CT in daily clinical practice is also described. PMID:27416996

Dose calculations accounting for breathing motion in stereotactic lung radiotherapy based on 4D-CT and the internal target volume.

PubMed

Admiraal, Marjan A; Schuring, Danny; Hurkmans, Coen W

2008-01-01

The purpose of this study was to determine the 4D accumulated dose delivered to the CTV in stereotactic radiotherapy of lung tumours, for treatments planned on an average CT using an ITV derived from the Maximum Intensity Projection (MIP) CT. For 10 stage I lung cancer patients, treatment plans were generated based on 4D-CT images. From the 4D-CT scan, 10 time-sorted breathing phases were derived, along with the average CT and the MIP. The ITV with a margin of 0mm was used as a PTV to study a worst case scenario in which the differences between 3D planning and 4D dose accumulation will be largest. Dose calculations were performed on the average CT. Dose prescription was 60Gy to 95% of the PTV, and at least 54Gy should be received by 99% of the PTV. Plans were generated using the inverse planning module of the Pinnacle(3) treatment planning system. The plans consisted of nine coplanar beams with two segments each. After optimisation, the treatment plan was transferred to all breathing phases and the delivered dose per phase was calculated using an elastic body spline model available in our research version of Pinnacle (8.1r). Then, the cumulative dose to the CTV over all breathing phases was calculated and compared to the dose distribution of the original treatment plan. Although location, tumour size and breathing-induced tumour movement varied widely between patients, the PTV planning criteria could always be achieved without compromising organs at risk criteria. After 4D dose calculations, only very small differences between the initial planned PTV coverage and resulting CTV coverage were observed. For all patients, the dose delivered to 99% of the CTV exceeded 54Gy. For nine out of 10 patients also the criterion was met that the volume of the CTV receiving at least the prescribed dose was more than 95%. When the target dose is prescribed to the ITV (PTV=ITV) and dose calculations are performed on the average CT, the cumulative CTV dose compares well to the planned dose to the ITV. Thus, the concept of treatment plan optimisation and evaluation based on the average CT and the ITV is a valid approach in stereotactic lung treatment. Even with a zero ITV to PTV margin, no significantly different dose coverage of the CTV arises from the breathing motion induced dose variation over time.

Randomized phase III trial of postoperative radiochemotherapy +/- amifostine in head and neck cancer. Is there evidence for radioprotection?

PubMed

Vacha, Peter; Fehlauer, Fabian; Mahlmann, Birgit; Marx, Meinolf; Hinke, Axel; Sommer, Konrad; Richter, Eckart; Feyerabend, Thomas

2003-06-01

Experimental and clinical data suggest a reduction of radiation-induced acute toxicity by amifostine (A). We investigated this issue in a randomized trial comparing radiochemotherapy (RT + CT) versus radiochemotherapy plus amifostine (RC + CT + A) in patients with head and neck cancer. 56 patients with oro-/hypopharynx or larynx cancer (T1-2 N1-2 G3, T3-4 N0-2 G1-3) were randomized to receive RC + CT alone or RC + CT + A. Patients were irradiated up to 60 Gy (R0) or 70 Gy (R1/2) and received chemotherapy (70 mg/m(2) carboplatin, day 1-5 in week 1 and 5 of radiotherapy). 250 mg amifostine were applied daily before each radiotherapy session. Acute toxicity was evaluated according to the Common Toxicity Criteria (CTC). As for acute xerostomia, patients with laryngeal cancer were excluded from evaluation. 50 patients were evaluable (25 patients in the RC + CT, 25 patients in the RC + CT + A group). Clinical characteristics were well balanced in both treatment groups. Amifostine provided reduction in acute xerostomia and mucositis but had no obvious influence on Karnofsky performance status, body weight, cutaneous side effects, and alopecia. The differences between both groups were statistically significant for acute xerostomia and nonsignificant, but with a trend for mucositis. According to our results, there is a radioprotective effect on salivary glands and a potential effect on oral mucosa by amifostine in postoperative radiotherapy combined with carboplatin. To improve the radio- and chemoprotective effects of amifostine in clinical practice, the application of a higher dose (> 250 mg) seems to be necessary.

A review of setup error in supine breast radiotherapy using cone-beam computed tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Batumalai, Vikneswary, E-mail: Vikneswary.batumalai@sswahs.nsw.gov.au; Liverpool and Macarthur Cancer Therapy Centres, New South Wales; Ingham Institute of Applied Medical Research, Sydney, New South Wales

2016-10-01

Setup error in breast radiotherapy (RT) measured with 3-dimensional cone-beam computed tomography (CBCT) is becoming more common. The purpose of this study is to review the literature relating to the magnitude of setup error in breast RT measured with CBCT. The different methods of image registration between CBCT and planning computed tomography (CT) scan were also explored. A literature search, not limited by date, was conducted using Medline and Google Scholar with the following key words: breast cancer, RT, setup error, and CBCT. This review includes studies that reported on systematic and random errors, and the methods used when registeringmore » CBCT scans with planning CT scan. A total of 11 relevant studies were identified for inclusion in this review. The average magnitude of error is generally less than 5 mm across a number of studies reviewed. The common registration methods used when registering CBCT scans with planning CT scan are based on bony anatomy, soft tissue, and surgical clips. No clear relationships between the setup errors detected and methods of registration were observed from this review. Further studies are needed to assess the benefit of CBCT over electronic portal image, as CBCT remains unproven to be of wide benefit in breast RT.« less

Office-Based Three-Dimensional Printing Workflow for Craniomaxillofacial Fracture Repair.

PubMed

Elegbede, Adekunle; Diaconu, Silviu C; McNichols, Colton H L; Seu, Michelle; Rasko, Yvonne M; Grant, Michael P; Nam, Arthur J

2018-03-08

Three-dimensional printing of patient-specific models is being used in various aspects of craniomaxillofacial reconstruction. Printing is typically outsourced to off-site vendors, with the main disadvantages being increased costs and time for production. Office-based 3-dimensional printing has been proposed as a means to reduce costs and delays, but remains largely underused because of the perception among surgeons that it is futuristic, highly technical, and prohibitively expensive. The goal of this report is to demonstrate the feasibility and ease of incorporating in-office 3-dimensional printing into the standard workflow for facial fracture repair.Patients with complex mandible fractures requiring open repair were identified. Open-source software was used to create virtual 3-dimensional skeletal models of the, initial injury pattern, and then the ideally reduced fractures based on preoperative computed tomography (CT) scan images. The virtual 3-dimensional skeletal models were then printed in our office using a commercially available 3-dimensional printer and bioplastic filament. The 3-dimensional skeletal models were used as templates to bend and shape titanium plates that were subsequently used for intraoperative fixation.Average print time was 6 hours. Excluding the 1-time cost of the 3-dimensional printer of $2500, roughly the cost of a single commercially produced model, the average material cost to print 1 model mandible was $4.30. Postoperative CT imaging demonstrated precise, predicted reduction in all patients.Office-based 3-dimensional printing of skeletal models can be routinely used in repair of facial fractures in an efficient and cost-effective manner.

Radiation therapy planning and simulation with magnetic resonance images

NASA Astrophysics Data System (ADS)

Boettger, Thomas; Nyholm, Tufve; Karlsson, Magnus; Nunna, Chandrasekhar; Celi, Juan Carlos

2008-03-01

We present a system which allows for use of magnetic resonance (MR) images as primary RT workflow modality alone and no longer limits the user to computed tomography data for radiation therapy (RT) planning, simulation and patient localization. The single steps for achieving this goal are explained in detail. For planning two MR data sets, MR1 and MR2 are acquired sequentially. For MR1 a standardized Ultrashort TE (UTE) sequence is used enhancing bony anatomy. The sequence for MR2 is chosen to get optimal contrast for the target and the organs at risk for each individual patient. Both images are naturally in registration, neglecting elastic soft tissue deformations. The planning software first automatically extracts skin and bony anatomy from MR1. The user can semi-automatically delineate target structures and organs at risk based on MR1 or MR2, associate all segmentations with MR1 and create a plan in the coordinate system of MR1. Projections similar to digitally reconstructed radiographs (DRR) enhancing bony anatomy are calculated from the MR1 directly and can be used for iso-center definition and setup verification. Furthermore we present a method for creating a Pseudo-CT data set which assigns electron densities to the voxels of MR1 based on the skin and bone segmentations. The Pseudo-CT is then used for dose calculation. Results from first tests under clinical conditions show the feasibility of the completely MR based workflow in RT for necessary clinical cases. It needs to be investigated in how far geometrical distortions influence accuracy of MR-based RT planning.

Dynamic CT myocardial perfusion imaging: performance of 3D semi-automated evaluation software.

PubMed

Ebersberger, Ullrich; Marcus, Roy P; Schoepf, U Joseph; Lo, Gladys G; Wang, Yining; Blanke, Philipp; Geyer, Lucas L; Gray, J Cranston; McQuiston, Andrew D; Cho, Young Jun; Scheuering, Michael; Canstein, Christian; Nikolaou, Konstantin; Hoffmann, Ellen; Bamberg, Fabian

2014-01-01

To evaluate the performance of three-dimensional semi-automated evaluation software for the assessment of myocardial blood flow (MBF) and blood volume (MBV) at dynamic myocardial perfusion computed tomography (CT). Volume-based software relying on marginal space learning and probabilistic boosting tree-based contour fitting was applied to CT myocardial perfusion imaging data of 37 subjects. In addition, all image data were analysed manually and both approaches were compared with SPECT findings. Study endpoints included time of analysis and conventional measures of diagnostic accuracy. Of 592 analysable segments, 42 showed perfusion defects on SPECT. Average analysis times for the manual and software-based approaches were 49.1 ± 11.2 and 16.5 ± 3.7 min respectively (P < 0.01). There was strong agreement between the two measures of interest (MBF, ICC = 0.91, and MBV, ICC = 0.88, both P < 0.01) and no significant difference in MBF/MBV with respect to diagnostic accuracy between the two approaches for both MBF and MBV for manual versus software-based approach; respectively; all comparisons P > 0.05. Three-dimensional semi-automated evaluation of dynamic myocardial perfusion CT data provides similar measures and diagnostic accuracy to manual evaluation, albeit with substantially reduced analysis times. This capability may aid the integration of this test into clinical workflows. • Myocardial perfusion CT is attractive for comprehensive coronary heart disease assessment. • Traditional image analysis methods are cumbersome and time-consuming. • Automated 3D perfusion software shortens analysis times. • Automated 3D perfusion software increases standardisation of myocardial perfusion CT. • Automated, standardised analysis fosters myocardial perfusion CT integration into clinical practice.

A digital model individual template and CT-guided 125I seed implants for malignant tumors of the head and neck.

PubMed

Huang, Ming-Wei; Liu, Shu-Ming; Zheng, Lei; Shi, Yan; Zhang, Jie; Li, Yan-Sheng; Yu, Guang-Yan; Zhang, Jian-Guo

2012-11-01

To enhance the accuracy of radioactive seed implants in the head and neck, a digital model individual template, containing information simultaneously on needle pathway and facial features, was designed to guide implantation with CT imaging. Thirty-one patients with recurrent and local advanced malignant tumors of head and neck after prior surgery and radiotherapy were involved in this study. Before (125)I implants, patients received CT scans based on 0.75mm thickness. And the brachytherapy treatment planning system (BTPS) software was used to make the implantation plan based on the CT images. Mimics software and Geomagic software were used to read the data containing CT images and implantation plan, and to design the individual template. Then the individual template containing the information of needle pathway and face features simultaneously was made through rapid prototyping (RP) technique. All patients received (125)I seeds interstitial implantation under the guide of the individual template and CT. The individual templates were positioned easily and accurately, and were stable. After implants, treatment quality evaluation was made by CT and TPS. The seeds and dosages distribution (D(90),V(100),V(150)) were well meet the treatment requirement. Clinical practice confirms that this approach can facilitate easier and more accurate implantation.

Development of real-time motion verification system using in-room optical images for respiratory-gated radiotherapy.

PubMed

Park, Yang-Kyun; Son, Tae-geun; Kim, Hwiyoung; Lee, Jaegi; Sung, Wonmo; Kim, Il Han; Lee, Kunwoo; Bang, Young-bong; Ye, Sung-Joon

2013-09-06

Phase-based respiratory-gated radiotherapy relies on the reproducibility of patient breathing during the treatment. To monitor the positional reproducibility of patient breathing against a 4D CT simulation, we developed a real-time motion verification system (RMVS) using an optical tracking technology. The system in the treatment room was integrated with a real-time position management system. To test the system, an anthropomorphic phantom that was mounted on a motion platform moved on a programmed breathing pattern and then underwent a 4D CT simulation with RPM. The phase-resolved anterior surface lines were extracted from the 4D CT data to constitute 4D reference lines. In the treatment room, three infrared reflective markers were attached on the superior, middle, and inferior parts of the phantom along with the body midline and then RMVS could track those markers using an optical camera system. The real-time phase information extracted from RPM was delivered to RMVS via in-house network software. Thus, the real-time anterior-posterior positions of the markers were simultaneously compared with the 4D reference lines. The technical feasibility of RMVS was evaluated by repeating the above procedure under several scenarios such as ideal case (with identical motion parameters between simulation and treatment), cycle change, baseline shift, displacement change, and breathing type changes (abdominal or chest breathing). The system capability for operating under irregular breathing was also investigated using real patient data. The evaluation results showed that RMVS has a competence to detect phase-matching errors between patient's motion during the treatment and 4D CT simulation. Thus, we concluded that RMVS could be used as an online quality assurance tool for phase-based gating treatments.

Shading correction for cone-beam CT in radiotherapy: validation of dose calculation accuracy using clinical images

NASA Astrophysics Data System (ADS)

Marchant, T. E.; Joshi, K. D.; Moore, C. J.

2017-03-01

Cone-beam CT (CBCT) images are routinely acquired to verify patient position in radiotherapy (RT), but are typically not calibrated in Hounsfield Units (HU) and feature non-uniformity due to X-ray scatter and detector persistence effects. This prevents direct use of CBCT for re-calculation of RT delivered dose. We previously developed a prior-image based correction method to restore HU values and improve uniformity of CBCT images. Here we validate the accuracy with which corrected CBCT can be used for dosimetric assessment of RT delivery, using CBCT images and RT plans for 45 patients including pelvis, lung and head sites. Dose distributions were calculated based on each patient's original RT plan and using CBCT image values for tissue heterogeneity correction. Clinically relevant dose metrics were calculated (e.g. median and minimum target dose, maximum organ at risk dose). Accuracy of CBCT based dose metrics was determined using an "override ratio" method where the ratio of the dose metric to that calculated on a bulk-density assigned version of the image is assumed to be constant for each patient, allowing comparison to "gold standard" CT. For pelvis and head images the proportion of dose errors >2% was reduced from 40% to 1.3% after applying shading correction. For lung images the proportion of dose errors >3% was reduced from 66% to 2.2%. Application of shading correction to CBCT images greatly improves their utility for dosimetric assessment of RT delivery, allowing high confidence that CBCT dose calculations are accurate within 2-3%.

Radiological changes with magnetic resonance imaging and computed tomography after irradiating minipig mandibles: The role of T2-SPIR mixed signal intensities in the detection of osteoradionecrosis.

PubMed

Poort, Lucas J; Postma, Alida A; Stadler, Annika A R; Böckmann, Roland A; Hoebers, Frank J; Kessler, Peter A W H

2017-05-01

Radiotherapy in the head and neck can induce several radiologically detectable changes in bone, osteoradionecrosis (ORN) among them. The purpose is to investigate radiological changes in mandibular bone after irradiation with various doses with and without surgery and to determine imaging characteristics of radiotherapy and ORN in an animal model. Sixteen Göttingen minipigs were divided into groups and were irradiated with two fractions with equivalent doses of 0, 25, 50 and 70 Gray. Thirteen weeks after irradiation, left mandibular teeth were removed and dental implants were placed. CT-scans and MR-imaging were made before irradiation and twenty-six weeks after. Alterations in the bony structures were recorded on CT-scan and MR-imaging and scored by two head-neck radiologists. Increased signal changes on MR-imaging were associated with higher radiation doses. Two animals developed ORN clinically. Radiologically mixed signal intensities on T2-SPIR were seen. On CT-scans cortical destruction was found in three animals. Based on imaging, three animals were diagnosed with ORN. Irradiation of minipig mandibles with various doses induced damages of the mandibular bone. Imaging with CT-scan and MR-imaging showed signal and structural changes that can be interpreted as prolonged and insufficient repair of radiation induced bone damages. Copyright © 2017 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

X-ray Computed Tomography.

ERIC Educational Resources Information Center

Michael, Greg

2001-01-01

Describes computed tomography (CT), a medical imaging technique that produces images of transaxial planes through the human body. A CT image is reconstructed mathematically from a large number of one-dimensional projections of a plane. The technique is used in radiological examinations and radiotherapy treatment planning. (Author/MM)

Comparison of 3 different postimplant dosimetry methods following permanent {sup 125}I prostate seed brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marcu, Loredana G., E-mail: loredana@marcunet.com; Faculty of Science, University of Oradea; School of Chemistry and Physics, University of Adelaide, South Australia

2013-10-01

Postimplant dosimetry (PID) after Iodine-125 ({sup 125}I) implant of the prostate should offer a reliable qualitative assessment. So far, there is no consensus regarding the optimum PID method, though the latest literature is in favor of magnetic resonance imaging (MRI). This study aims to simultaneously compare 3 PID techniques: (1) MRI-computed tomography (CT) fusion; (2) ultrasound (US)-CT fusion; and (3) manual target delineation on CT. The study comprised 10 patients with prostate cancer. CT/MR scans with urinary catheters in place for PID were done either on day 0 or day 1 postimplantation. The main parameter evaluated and compared among methodsmore » was target D90. The results show that CT-based D90s are lower than US-CT D90s (median difference,−6.85%), whereas MR-CT PID gives higher D90 than US-CT PID (median difference, 4.25%). Manual contouring on CT images tends to overestimate the prostate volume compared with transrectal ultrasound (TRUS) (median difference, 23.33%), whereas on US images the target is overestimated compared with MR-based contouring (median difference, 13.25%). Although there are certain differences among the results given by various PID techniques, the differences are statistically insignificant for this small group of patients. Any dosimetric comparison between 2 PID techniques should also account for the limitations of each technique, to allow for an accurate quantification of data. Given that PID after permanent radioactive seed implant is mandatory for quality assurance, any imaging method–based PID (MR-CT, US-CT, and CT) available in a radiotherapy department can be indicative of the quality of the procedure.« less

A proposed framework for consensus-based lung tumour volume auto-segmentation in 4D computed tomography imaging

NASA Astrophysics Data System (ADS)

Martin, Spencer; Brophy, Mark; Palma, David; Louie, Alexander V.; Yu, Edward; Yaremko, Brian; Ahmad, Belal; Barron, John L.; Beauchemin, Steven S.; Rodrigues, George; Gaede, Stewart

2015-02-01

This work aims to propose and validate a framework for tumour volume auto-segmentation based on ground-truth estimates derived from multi-physician input contours to expedite 4D-CT based lung tumour volume delineation. 4D-CT datasets of ten non-small cell lung cancer (NSCLC) patients were manually segmented by 6 physicians. Multi-expert ground truth (GT) estimates were constructed using the STAPLE algorithm for the gross tumour volume (GTV) on all respiratory phases. Next, using a deformable model-based method, multi-expert GT on each individual phase of the 4D-CT dataset was propagated to all other phases providing auto-segmented GTVs and motion encompassing internal gross target volumes (IGTVs) based on GT estimates (STAPLE) from each respiratory phase of the 4D-CT dataset. Accuracy assessment of auto-segmentation employed graph cuts for 3D-shape reconstruction and point-set registration-based analysis yielding volumetric and distance-based measures. STAPLE-based auto-segmented GTV accuracy ranged from (81.51  ±  1.92) to (97.27  ±  0.28)% volumetric overlap of the estimated ground truth. IGTV auto-segmentation showed significantly improved accuracies with reduced variance for all patients ranging from 90.87 to 98.57% volumetric overlap of the ground truth volume. Additional metrics supported these observations with statistical significance. Accuracy of auto-segmentation was shown to be largely independent of selection of the initial propagation phase. IGTV construction based on auto-segmented GTVs within the 4D-CT dataset provided accurate and reliable target volumes compared to manual segmentation-based GT estimates. While inter-/intra-observer effects were largely mitigated, the proposed segmentation workflow is more complex than that of current clinical practice and requires further development.

A proposed framework for consensus-based lung tumour volume auto-segmentation in 4D computed tomography imaging.

PubMed

Martin, Spencer; Brophy, Mark; Palma, David; Louie, Alexander V; Yu, Edward; Yaremko, Brian; Ahmad, Belal; Barron, John L; Beauchemin, Steven S; Rodrigues, George; Gaede, Stewart

2015-02-21

This work aims to propose and validate a framework for tumour volume auto-segmentation based on ground-truth estimates derived from multi-physician input contours to expedite 4D-CT based lung tumour volume delineation. 4D-CT datasets of ten non-small cell lung cancer (NSCLC) patients were manually segmented by 6 physicians. Multi-expert ground truth (GT) estimates were constructed using the STAPLE algorithm for the gross tumour volume (GTV) on all respiratory phases. Next, using a deformable model-based method, multi-expert GT on each individual phase of the 4D-CT dataset was propagated to all other phases providing auto-segmented GTVs and motion encompassing internal gross target volumes (IGTVs) based on GT estimates (STAPLE) from each respiratory phase of the 4D-CT dataset. Accuracy assessment of auto-segmentation employed graph cuts for 3D-shape reconstruction and point-set registration-based analysis yielding volumetric and distance-based measures. STAPLE-based auto-segmented GTV accuracy ranged from (81.51  ±  1.92) to (97.27  ±  0.28)% volumetric overlap of the estimated ground truth. IGTV auto-segmentation showed significantly improved accuracies with reduced variance for all patients ranging from 90.87 to 98.57% volumetric overlap of the ground truth volume. Additional metrics supported these observations with statistical significance. Accuracy of auto-segmentation was shown to be largely independent of selection of the initial propagation phase. IGTV construction based on auto-segmented GTVs within the 4D-CT dataset provided accurate and reliable target volumes compared to manual segmentation-based GT estimates. While inter-/intra-observer effects were largely mitigated, the proposed segmentation workflow is more complex than that of current clinical practice and requires further development.

Simulation of dosimetric consequences of 4D-CT-based motion margin estimation for proton radiotherapy using patient tumor motion data

NASA Astrophysics Data System (ADS)

Koybasi, Ozhan; Mishra, Pankaj; St. James, Sara; Lewis, John H.; Seco, Joao

2014-02-01

For the radiation treatment of lung cancer patients, four-dimensional computed tomography (4D-CT) is a common practice used clinically to image tumor motion and subsequently determine the internal target volume (ITV) from the maximum intensity projection (MIP) images. ITV, which is derived from short pre-treatment 4D-CT scan (<6 s per couch position), may not adequately cover the extent of tumor motion during the treatment, particularly for patients that exhibit a large respiratory variability. Inaccurate tumor localization may result in under-dosage of the tumor or over-dosage of the surrounding tissues. The purpose of this study is therefore to assess the degree of tumor under-dosage in case of regular and irregular breathing for proton radiotherapy using ITV-based treatment planning. We place a spherical lesion into a modified XCAT phantom that is also capable of producing 4D images based on irregular breathing, and move the tumor according to real tumor motion data, which is acquired over multiple days by tracking gold fiducial markers implanted into the lung tumors of patients. We derive ITVs by taking the union of all tumor positions during 6 s of tumor motion in the phantom using the first day patient tumor tracking data. This is equivalent to ITVs generated clinically from cine-mode 4D-CT MIP images. The treatment plans created for different ITVs are then implemented on dynamic phantoms with tumor motion governed by real tumor tracking data from consecutive days. By comparing gross tumor volume dose distribution on days of ‘treatment’ with the ITV dose distribution, we evaluate the deviation of the actually delivered dose from the predicted dose. Our results have shown that the proton treatment planning on ITV derived from pre-treatment cine-mode 4D-CT can result in under-dosage (dose covering 95% of volume) of the tumor by up to 25.7% over 3 min of treatment for the patient with irregular respiratory motion. Tumor under-dosage is less significant for the patient with relatively regular breathing. We have demonstrated that proton therapy using the pre-treatment 4D-CT based ITV method can lead to significant under-dosage of the tumor, highlighting the need for daily customization to generate a target volume that represents tumor positions during the treatment more accurately.

SU-E-T-04: 3D Dose Based Patient Compensator QA Procedure for Proton Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zou, W; Reyhan, M; Zhang, M

2015-06-15

Purpose: In proton double-scattering radiotherapy, compensators are the essential patient specific devices to contour the distal dose distribution to the tumor target. Traditional compensator QA is limited to checking the drilled surface profiles against the plan. In our work, a compensator QA process was established that assess the entire compensator including its internal structure for patient 3D dose verification. Methods: The fabricated patient compensators were CT scanned. Through mathematical image processing and geometric transformations, the CT images of the proton compensator were combined with the patient simulation CT images into a new series of CT images, in which the imagedmore » compensator is placed at the planned location along the corresponding beam line. The new CT images were input into the Eclipse treatment planning system. The original plan was calculated to the combined CT image series without the plan compensator. The newly computed patient 3D dose from the combined patientcompensator images was verified against the original plan dose. Test plans include the compensators with defects intentionally created inside the fabricated compensators. Results: The calculated 3D dose with the combined compensator and patient CT images reflects the impact of the fabricated compensator to the patient. For the test cases in which no defects were created, the dose distributions were in agreement between our method and the corresponding original plans. For the compensator with the defects, the purposely changed material and a purposely created internal defect were successfully detected while not possible with just the traditional compensator profiles detection methods. Conclusion: We present here a 3D dose verification process to qualify the fabricated proton double-scattering compensator. Such compensator detection process assesses the patient 3D impact of the fabricated compensator surface profile as well as the compensator internal material and structure changes. This research receives funding support from CURA Medical Technologies.« less

ImaSim, a software tool for basic education of medical x-ray imaging in radiotherapy and radiology

NASA Astrophysics Data System (ADS)

Landry, Guillaume; deBlois, François; Verhaegen, Frank

2013-11-01

Introduction: X-ray imaging is an important part of medicine and plays a crucial role in radiotherapy. Education in this field is mostly limited to textbook teaching due to equipment restrictions. A novel simulation tool, ImaSim, for teaching the fundamentals of the x-ray imaging process based on ray-tracing is presented in this work. ImaSim is used interactively via a graphical user interface (GUI). Materials and methods: The software package covers the main x-ray based medical modalities: planar kilo voltage (kV), planar (portal) mega voltage (MV), fan beam computed tomography (CT) and cone beam CT (CBCT) imaging. The user can modify the photon source, object to be imaged and imaging setup with three-dimensional editors. Objects are currently obtained by combining blocks with variable shapes. The imaging of three-dimensional voxelized geometries is currently not implemented, but can be added in a later release. The program follows a ray-tracing approach, ignoring photon scatter in its current implementation. Simulations of a phantom CT scan were generated in ImaSim and were compared to measured data in terms of CT number accuracy. Spatial variations in the photon fluence and mean energy from an x-ray tube caused by the heel effect were estimated from ImaSim and Monte Carlo simulations and compared. Results: In this paper we describe ImaSim and provide two examples of its capabilities. CT numbers were found to agree within 36 Hounsfield Units (HU) for bone, which corresponds to a 2% attenuation coefficient difference. ImaSim reproduced the heel effect reasonably well when compared to Monte Carlo simulations. Discussion: An x-ray imaging simulation tool is made available for teaching and research purposes. ImaSim provides a means to facilitate the teaching of medical x-ray imaging.

SU-G-JeP2-01: A New Approach for MR-Only Treatment Planning: Tissue Segmentation-Based Pseudo-CT Generation Using T1-Weighted MRI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, H; Leszczynski, K; Lee, Y

Purpose: To evaluate MR-only treatment planning for brain Stereotactic Ablative Radiotherapy (SABR) based on pseudo-CT (pCT) generation using one set of T1-weighted MRI. Methods: T1-weighted MR and CT images from 12 patients who were eligible for brain SABR were retrospectively acquired for this study. MR-based pCT was generated by using a newly in-house developed algorithm based on MR tissue segmentation and voxel-based electron density (ED) assignment (pCTv). pCTs using bulk density assignment (pCTb where bone and soft tissue were assigned 800HU and 0HU,respectively), and water density assignment (pCTw where all tissues were assigned 0HU) were generated for comparison of EDmore » assignment techniques. The pCTs were registered with CTs and contours of radiation targets and Organs-at-Risk (OARs) from clinical CT-based plans were copied to co-registered pCTs. Volumetric-Modulated-Arc-Therapy(VMAT) plans were independently created for pCTv and CT using the same optimization settings and a prescription (50Gy/10 fractions) to planning-target-volume (PTV) mean dose. pCTv-based plans and CT-based plans were compared with dosimetry parameters and monitor units (MUs). Beam fluence maps of CT-based plans were transferred to co-registered pCTs, and dose was recalculated on pCTs. Dose distribution agreement between pCTs and CT plans were quantified using Gamma analysis (2%/2mm, 1%/1mm with a 10% cut-off threshold) in axial, coronal and sagittal planes across PTV. Results: The average differences of PTV mean and maximum doses, and monitor units between independently created pCTv-based and CT-based plans were 0.5%, 1.5% and 1.1%, respectively. Gamma analysis of dose distributions of the pCTs and the CT calculated using the same fluence map resulted in average agreements of 92.6%/79.1%/52.6% with 1%/1mm criterion, and 98.7%/97.4%/71.5% with 2%/2mm criterion, for pCTv/CT, pCTb/CT and pCTw/CT, respectively. Conclusion: Plans produced on Voxel-based pCT is dosimetrically more similar to CT plans than bulk assignment-based pCTs. MR-only treatment planning using voxel-based pCT generated from T1-wieghted MRI may be feasible.« less

SEGMENTING CT PROSTATE IMAGES USING POPULATION AND PATIENT-SPECIFIC STATISTICS FOR RADIOTHERAPY.

PubMed

Feng, Qianjin; Foskey, Mark; Tang, Songyuan; Chen, Wufan; Shen, Dinggang

2009-08-07

This paper presents a new deformable model using both population and patient-specific statistics to segment the prostate from CT images. There are two novelties in the proposed method. First, a modified scale invariant feature transform (SIFT) local descriptor, which is more distinctive than general intensity and gradient features, is used to characterize the image features. Second, an online training approach is used to build the shape statistics for accurately capturing intra-patient variation, which is more important than inter-patient variation for prostate segmentation in clinical radiotherapy. Experimental results show that the proposed method is robust and accurate, suitable for clinical application.

SEGMENTING CT PROSTATE IMAGES USING POPULATION AND PATIENT-SPECIFIC STATISTICS FOR RADIOTHERAPY

PubMed Central

Feng, Qianjin; Foskey, Mark; Tang, Songyuan; Chen, Wufan; Shen, Dinggang

2010-01-01

This paper presents a new deformable model using both population and patient-specific statistics to segment the prostate from CT images. There are two novelties in the proposed method. First, a modified scale invariant feature transform (SIFT) local descriptor, which is more distinctive than general intensity and gradient features, is used to characterize the image features. Second, an online training approach is used to build the shape statistics for accurately capturing intra-patient variation, which is more important than inter-patient variation for prostate segmentation in clinical radiotherapy. Experimental results show that the proposed method is robust and accurate, suitable for clinical application. PMID:21197416

Flavonoid silybin improves the response to radiotherapy in invasive bladder cancer.

PubMed

Prack Mc Cormick, Barbara; Langle, Yanina; Belgorosky, Denise; Vanzulli, Silvia; Balarino, Natalia; Sandes, Eduardo; Eiján, Ana M

2018-01-24

Conservative treatment for invasive bladder cancer (BC) involves a complete transurethral tumor resection combined with chemotherapy (CT) and radiotherapy (RT). The major obstacles of chemo-radiotherapy are the addition of the toxicities of RT and CT, and the recurrence due to RT and CT resistances. The flavonoid Silybin (Sb) inhibits pathways involved in cell survival and resistance mechanisms, therefore the purpose of this paper was to study in vitro and in vivo, the ability of Sb to improve the response to RT, in two murine BC cell lines, with different levels of invasiveness, placing emphasis on radio-sensitivity, and pathways involved in radio-resistance and survival. In vitro, Sb radio-sensitized murine invasive cells through the inhibition of RT-induced NF-κB and PI3K pathways, and the increase of oxidative stress, while non-invasive cells did not show to be sensitized. In vivo, Sb improved RT-response and overall survival in invasive murine tumors. As Sb is already being tested in clinical trials for other urological cancers and it improves RT-response in invasive BC, these results could have translational relevance, supporting further research. © 2018 Wiley Periodicals, Inc.

Modality comparison for small animal radiotherapy: A simulation study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bazalova, Magdalena, E-mail: bazalova@stanford.edu; Nelson, Geoff; Noll, John M.

Purpose: Small animal radiation therapy has advanced significantly in recent years. Whereas in the past dose was delivered using a single beam and a lead shield for sparing of healthy tissue, conformal doses can be now delivered using more complex dedicated small animal radiotherapy systems with image guidance. The goal of this paper is to investigate dose distributions for three small animal radiation treatment modalities. Methods: This paper presents a comparison of dose distributions generated by the three approaches—a single-field irradiator with a 200 kV beam and no image guidance, a small animal image-guided conformal system based on a modified microCTmore » scanner with a 120 kV beam developed at Stanford University, and a dedicated conformal system, SARRP, using a 220 kV beam developed at Johns Hopkins University. The authors present a comparison of treatment plans for the three modalities using two cases: a mouse with a subcutaneous tumor and a mouse with a spontaneous lung tumor. A 5 Gy target dose was calculated using the EGSnrc Monte Carlo codes. Results: All treatment modalities generated similar dose distributions for the subcutaneous tumor case, with the highest mean dose to the ipsilateral lung and bones in the single-field plan (0.4 and 0.4 Gy) compared to the microCT (0.1 and 0.2 Gy) and SARRP (0.1 and 0.3 Gy) plans. The lung case demonstrated that due to the nine-beam arrangements in the conformal plans, the mean doses to the ipsilateral lung, spinal cord, and bones were significantly lower in the microCT plan (2.0, 0.4, and 1.9 Gy) and the SARRP plan (1.5, 0.5, and 1.8 Gy) than in single-field irradiator plan (4.5, 3.8, and 3.3 Gy). Similarly, the mean doses to the contralateral lung and the heart were lowest in the microCT plan (1.5 and 2.0 Gy), followed by the SARRP plan (1.7 and 2.2 Gy), and they were highest in the single-field plan (2.5 and 2.4 Gy). For both cases, dose uniformity was greatest in the single-field irradiator plan followed by the SARRP plan due to the sensitivity of the lower energy microCT beam to target heterogeneities and image noise. Conclusions: The two treatment planning examples demonstrate that modern small animal radiotherapy techniques employing image guidance, variable collimation, and multiple beam angles deliver superior dose distributions to small animal tumors as compared to conventional treatments using a single-field irradiator. For deep-seated mouse tumors, however, higher-energy conformal radiotherapy could result in higher doses to critical organs compared to lower-energy conformal radiotherapy. Treatment planning optimization for small animal radiotherapy should therefore be developed to take full advantage of the novel conformal systems.« less

Comparison study of portable bladder scanner versus cone-beam CT scan for measuring bladder volumes in post-prostatectomy patients undergoing radiotherapy.

PubMed

Ung, K A; White, R; Mathlum, M; Mak-Hau, V; Lynch, R

2014-01-01

In post-prostatectomy radiotherapy to the prostatic bed, consistent bladder volume is essential to maintain the position of treatment target volume. We assessed the differences between bladder volume readings from a portable bladder scanner (BS-V) and those obtained from planning CT (CT-V) or cone-beam CT (CBCT-V). Interfraction bladder volume variation was also determined. BS-V was recorded before and after planning CT or CBCT. The percentage differences between the readings using the two imaging modalities, standard deviations and 95% confidence intervals were determined. Data were analysed for the whole patient cohort and separately for the older BladderScan™ BVI3000 and newer BVI9400 model. Interfraction bladder volume variation was determined from the percentage difference between the CT-V and CBCT-V. Treatment duration, incorporating the time needed for BS and CBCT, was recorded. Fourteen patients were enrolled, producing 133 data sets for analysis. BS-V was taken using the BVI9400 in four patients (43 data sets). The mean BS-V was 253.2 mL, and the mean CT-V or CBCT-V was 199 cm(3). The mean percentage difference between the two modalities was 19.7% (SD 42.2; 95%CI 12.4 to 26.9). The BVI9400 model produced more consistent readings, with a mean percentage difference of -6.2% (SD 27.8; 95% CI -14.7 to -2.4%). The mean percentage difference between CT-V and CBCT-V was 31.3% (range -48% to 199.4%). Treatment duration from time of first BS reading to CBCT was, on average, 12 min (range 6-27). The BS produces bladder volume readings of an average 19.7% difference from CT-V or CBCT-V and can potentially be used to screen for large interfraction bladder volume variations in radiotherapy to prostatic bed. The observed interfraction bladder volume variation suggests the need to improve bladder volume consistency. Incorporating the BS into practice is feasible. © 2014 The Royal Australian and New Zealand College of Radiologists.

Implications of free breathing motion assessed by 4D-computed tomography on the delivered dose in radiotherapy for esophageal cancer.

PubMed

Duma, Marciana Nona; Berndt, Johannes; Rondak, Ina-Christine; Devecka, Michal; Wilkens, Jan J; Geinitz, Hans; Combs, Stephanie Elisabeth; Oechsner, Markus

2015-01-01

The aim of this study was to assess the effect of breathing motion on the delivered dose in esophageal cancer 3-dimensional (3D)-conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), and volumetric modulated arc therapy (VMAT). We assessed 16 patients with esophageal cancer. All patients underwent 4D-computed tomography (4D-CT) for treatment planning. For each of the analyzed patients, 1 3D-CRT, 1 IMRT, and 1 VMAT (RapidArc-RA) plan were calculated. Each of the 3 initial plans was recalculated on the 4D-CT (for the maximum free inspiration and maximum free expiration) to assess the effect of breathing motion. We assessed the minimum dose (Dmin) and mean dose (Dmean) to the esophagus within the planning target volume, the volume changes of the lungs, the Dmean and the total lung volume receiving at least 40Gy (V40), and the V30, V20, V10, and V5. For the heart we assessed the Dmean and the V25. Over all techniques and all patients the change in Dmean as compared with the planned Dmean (planning CT [PCT]) to the esophagus was 0.48% in maximum free inspiration (CT_insp) and 0.55% in maximum free expiration (CT_exp). The Dmin CT_insp change was 0.86% and CT_exp change was 0.89%. The Dmean change of the lungs (heart) was in CT_insp 1.95% (2.89%) and 3.88% (2.38%) in CT_exp. In all, 4 patients had a clinically relevant change of the dose (≥ 5% Dmean to the heart and the lungs) between inspiration and expiration. These patients had a very cranially or caudally situated tumor. There are no relevant differences in the delivered dose to the regions of interest among the 3 techniques. Breathing motion management could be considered to achieve a better sparing of the lungs or heart in patients with cranially or caudally situated tumors. Copyright © 2015 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

Implications of free breathing motion assessed by 4D-computed tomography on the delivered dose in radiotherapy for esophageal cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duma, Marciana Nona, E-mail: Marciana.Duma@mri.tum.de; Berndt, Johannes; Rondak, Ina-Christine

2015-01-01

The aim of this study was to assess the effect of breathing motion on the delivered dose in esophageal cancer 3-dimensional (3D)-conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), and volumetric modulated arc therapy (VMAT). We assessed 16 patients with esophageal cancer. All patients underwent 4D-computed tomography (4D-CT) for treatment planning. For each of the analyzed patients, 1 3D-CRT, 1 IMRT, and 1 VMAT (RapidArc—RA) plan were calculated. Each of the 3 initial plans was recalculated on the 4D-CT (for the maximum free inspiration and maximum free expiration) to assess the effect of breathing motion. We assessed the minimum dose (D{sub min})more » and mean dose (D{sub mean}) to the esophagus within the planning target volume, the volume changes of the lungs, the D{sub mean} and the total lung volume receiving at least 40 Gy (V{sub 40}), and the V{sub 30}, V{sub 20}, V{sub 10}, and V{sub 5}. For the heart we assessed the D{sub mean} and the V{sub 25}. Over all techniques and all patients the change in D{sub mean} as compared with the planned D{sub mean} (planning CT [PCT]) to the esophagus was 0.48% in maximum free inspiration (CT-insp) and 0.55% in maximum free expiration (CT-exp). The D{sub min} CT-insp change was 0.86% and CT-exp change was 0.89%. The D{sub mean} change of the lungs (heart) was in CT-insp 1.95% (2.89%) and 3.88% (2.38%) in CT-exp. In all, 4 patients had a clinically relevant change of the dose (≥ 5% D{sub mean} to the heart and the lungs) between inspiration and expiration. These patients had a very cranially or caudally situated tumor. There are no relevant differences in the delivered dose to the regions of interest among the 3 techniques. Breathing motion management could be considered to achieve a better sparing of the lungs or heart in patients with cranially or caudally situated tumors.« less

A software tool of digital tomosynthesis application for patient positioning in radiotherapy.

PubMed

Yan, Hui; Dai, Jian-Rong

2016-03-08

Digital Tomosynthesis (DTS) is an image modality in reconstructing tomographic images from two-dimensional kV projections covering a narrow scan angles. Comparing with conventional cone-beam CT (CBCT), it requires less time and radiation dose in data acquisition. It is feasible to apply this technique in patient positioning in radiotherapy. To facilitate its clinical application, a software tool was developed and the reconstruction processes were accelerated by graphic process-ing unit (GPU). Two reconstruction and two registration processes are required for DTS application which is different from conventional CBCT application which requires one image reconstruction process and one image registration process. The reconstruction stage consists of productions of two types of DTS. One type of DTS is reconstructed from cone-beam (CB) projections covering a narrow scan angle and is named onboard DTS (ODTS), which represents the real patient position in treatment room. Another type of DTS is reconstructed from digitally reconstructed radiography (DRR) and is named reference DTS (RDTS), which represents the ideal patient position in treatment room. Prior to the reconstruction of RDTS, The DRRs are reconstructed from planning CT using the same acquisition setting of CB projections. The registration stage consists of two matching processes between ODTS and RDTS. The target shift in lateral and longitudinal axes are obtained from the matching between ODTS and RDTS in coronal view, while the target shift in longitudinal and vertical axes are obtained from the matching between ODTS and RDTS in sagittal view. In this software, both DRR and DTS reconstruction algorithms were implemented on GPU environments for acceleration purpose. The comprehensive evaluation of this software tool was performed including geometric accuracy, image quality, registration accuracy, and reconstruction efficiency. The average correlation coefficient between DRR/DTS generated by GPU-based algorithm and CPU-based algorithm is 0.99. Based on the measurements of cube phantom on DTS, the geometric errors are within 0.5 mm in three axes. For both cube phantom and pelvic phantom, the registration errors are within 0.5 mm in three axes. Compared with reconstruction performance of CPU-based algorithms, the performances of DRR and DTS reconstructions are improved by a factor of 15 to 20. A GPU-based software tool was developed for DTS application for patient positioning of radiotherapy. The geometric and registration accuracy met the clinical requirement in patient setup of radiotherapy. The high performance of DRR and DTS reconstruction algorithms was achieved by the GPU-based computation environments. It is a useful software tool for researcher and clinician in evaluating DTS application in patient positioning of radiotherapy.

Investigation of 3D histograms of oriented gradients for image-based registration of CT with interventional CBCT

NASA Astrophysics Data System (ADS)

Trimborn, Barbara; Wolf, Ivo; Abu-Sammour, Denis; Henzler, Thomas; Schad, Lothar R.; Zöllner, Frank G.

2017-03-01

Image registration of preprocedural contrast-enhanced CTs to intraprocedual cone-beam computed tomography (CBCT) can provide additional information for interventional liver oncology procedures such as transcatheter arterial chemoembolisation (TACE). In this paper, a novel similarity metric for gradient-based image registration is proposed. The metric relies on the patch-based computation of histograms of oriented gradients (HOG) building the basis for a feature descriptor. The metric was implemented in a framework for rigid 3D-3D-registration of pre-interventional CT with intra-interventional CBCT data obtained during the workflow of a TACE. To evaluate the performance of the new metric, the capture range was estimated based on the calculation of the mean target registration error and compared to the results obtained with a normalized cross correlation metric. The results show that 3D HOG feature descriptors are suitable as image-similarity metric and that the novel metric can compete with established methods in terms of registration accuracy

SU-C-213-03: Custom 3D Printed Boluses for Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, B; Yang, M; Yan, Y

2015-06-15

Purpose: To develop a clinical workflow and to commission the process of creating custom 3d printed boluses for radiation therapy. Methods: We designed a workflow to create custom boluses using a commercial 3D printer. Contours of several patients were deformably mapped to phantoms where the test bolus contours were designed. Treatment plans were created on the phantoms following our institutional planning guideline. The DICOM file of the bolus contours were then converted to stereoLithography (stl) file for the 3d printer. The boluses were printed on a commercial 3D printer using polylactic acid (PLA) material. Custom printing parameters were optimized inmore » order to meet the requirement of bolus composition. The workflow was tested on multiple anatomical sites such as skull, nose and chest wall. The size of boluses varies from 6×9cm2 to 12×25cm2. To commission the process, basic CT and dose properties of the printing materials were measured in photon and electron beams and compared against water and soft superflab bolus. Phantoms were then scanned to confirm the placement of custom boluses. Finally dose distributions with rescanned CTs were compared with those computer-generated boluses. Results: The relative electron density(1.08±0.006) of the printed boluses resemble those of liquid tap water(1.04±0.004). The dosimetric properties resemble those of liquid tap water(1.04±0.004). The dosimetric properties were measured at dmax with an ion chamber in electron and photon open beams. Compared with solid water and soft bolus, the output difference was within 1% for the 3D printer material. The printed boluses fit well to the phantom surfaces on CT scans. The dose distribution and DVH based on the printed boluses match well with those based on TPS generated boluses. Conclusion: 3d printing provides a cost effective and convenient solution for patient-specific boluses in radiation therapy.« less

SU-E-J-145: Geometric Uncertainty in CBCT Extrapolation for Head and Neck Adaptive Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, C; Kumarasiri, A; Chetvertkov, M

2014-06-01

Purpose: One primary limitation of using CBCT images for H'N adaptive radiotherapy (ART) is the limited field of view (FOV) range. We propose a method to extrapolate the CBCT by using a deformed planning CT for the dose of the day calculations. The aim was to estimate the geometric uncertainty of our extrapolation method. Methods: Ten H'N patients, each with a planning CT (CT1) and a subsequent CT (CT2) taken, were selected. Furthermore, a small FOV CBCT (CT2short) was synthetically created by cropping CT2 to the size of a CBCT image. Then, an extrapolated CBCT (CBCTextrp) was generated by deformablymore » registering CT1 to CT2short and resampling with a wider FOV (42mm more from the CT2short borders), where CT1 is deformed through translation, rigid, affine, and b-spline transformations in order. The geometric error is measured as the distance map ||DVF|| produced by a deformable registration between CBCTextrp and CT2. Mean errors were calculated as a function of the distance away from the CBCT borders. The quality of all the registrations was visually verified. Results: Results were collected based on the average numbers from 10 patients. The extrapolation error increased linearly as a function of the distance (at a rate of 0.7mm per 1 cm) away from the CBCT borders in the S/I direction. The errors (μ±σ) at the superior and inferior boarders were 0.8 ± 0.5mm and 3.0 ± 1.5mm respectively, and increased to 2.7 ± 2.2mm and 5.9 ± 1.9mm at 4.2cm away. The mean error within CBCT borders was 1.16 ± 0.54mm . The overall errors within 4.2cm error expansion were 2.0 ± 1.2mm (sup) and 4.5 ± 1.6mm (inf). Conclusion: The overall error in inf direction is larger due to more large unpredictable deformations in the chest. The error introduced by extrapolation is plan dependent. The mean error in the expanded region can be large, and must be considered during implementation. This work is supported in part by Varian Medical Systems, Palo Alto, CA.« less

[A Case of Effective Chemoradiotherapy Using mFOLFOX6 for Locally Advanced Rectal Cancer].

PubMed

Kuga, Yoshio; Kitamura, Shosuke; Mouri, Teruo; Miwata, Tomohiro; Hirata, Yuzoh; Ishizaki, Yasuyo; Hashimoto, Yasutoshi

2017-05-01

We report a case of locally advanced rectal cancer, treated effectively with chemotherapy consisting of mFOLFOX6 combined with radiotherapy. A 63-year-old man was admitted to our hospital in March 2012 for diarrhea and anal and perineal pain. Advanced rectal cancer with invasion ofthe right perineum was diagnosed based on computer tomography(CT) findings. Surgery was performed; however, the rectal cancer was unresectable. A sigmoid colostomy was performed, and a central venous port was implanted. In April 2012, the patient was treated with chemotherapy using 3 courses ofmFOLFOX6 and concurrent radiotherapy. Radiotherapy at 2 Gy/day was administered 25 times(total dose, 50 Gy). After chemoradiotherapy, the patient underwent 3 courses ofmFOLFOX6 as an additional therapy. By June 2012, CT showed resolution ofthe tumor in the right perineum and a marked decrease in the size ofthe primary rectal cancer. Because the patient refused surgery, we started treatment with combination chemotherapy using oral S-1 and intravenous CPT-11 in August 2012. After 18 courses, the treatment was changed to oral administration ofS -1 alone, which was continued for 1 year. The patient remained well without recurrence for 54 months since the original diagnosis. Therefore, chemoradiotherapy with mFOLFOX6 is a possible option for the management of advanced rectal cancer.

Improving the accuracy of ionization chamber dosimetry in small megavoltage x-ray fields

NASA Astrophysics Data System (ADS)

McNiven, Andrea L.

The dosimetry of small x-ray fields is difficult, but important, in many radiation therapy delivery methods. The accuracy of ion chambers for small field applications, however, is limited due to the relatively large size of the chamber with respect to the field size, leading to partial volume effects, lateral electronic disequilibrium and calibration difficulties. The goal of this dissertation was to investigate the use of ionization chambers for the purpose of dosimetry in small megavoltage photon beams with the aim of improving clinical dose measurements in stereotactic radiotherapy and helical tomotherapy. A new method for the direct determination of the sensitive volume of small-volume ion chambers using micro computed tomography (muCT) was investigated using four nominally identical small-volume (0.56 cm3) cylindrical ion chambers. Agreement between their measured relative volume and ionization measurements (within 2%) demonstrated the feasibility of volume determination through muCT. Cavity-gas calibration coefficients were also determined, demonstrating the promise for accurate ion chamber calibration based partially on muCT. The accuracy of relative dose factor measurements in 6MV stereotactic x-ray fields (5 to 40mm diameter) was investigated using a set of prototype plane-parallel ionization chambers (diameters of 2, 4, 10 and 20mm). Chamber and field size specific correction factors ( CSFQ ), that account for perturbation of the secondary electron fluence, were calculated using Monte Carlo simulation methods (BEAM/EGSnrc simulations). These correction factors (e.g. CSFQ = 1.76 (2mm chamber, 5mm field) allow for accurate relative dose factor (RDF) measurement when applied to ionization readings, under conditions of electronic disequilibrium. With respect to the dosimetry of helical tomotherapy, a novel application of the ion chambers was developed to characterize the fan beam size and effective dose rate. Characterization was based on an adaptation of the computed tomography dose index (CTDI), a concept normally used in diagnostic radiology. This involved experimental determination of the fan beam thickness using the ion chambers to acquire fan beam profiles and extrapolation to a 'zero-size' detector. In conclusion, improvements have been made in the accuracy of small field dosimetry measurements in stereotactic radiotherapy and helical tomotherapy. This was completed through introduction of an original technique involving micro-CT imaging for sensitive volume determination and potentially ion chamber calibration coefficients, the use of appropriate Monte Carlo derived correction factors for RDF measurement, and the exploitation of the partial volume effect for helical tomotherapy fan beam dosimetry. With improved dosimetry for a wide range of challenging small x-ray field situations, it is expected that the patient's radiation safety will be maintained, and that clinical trials will adopt calibration protocols specialized for modern radiotherapy with small fields or beamlets. Keywords. radiation therapy, ionization chambers, small field dosimetry, stereotactic radiotherapy, helical tomotherapy, micro-CT.

68Ga-Prostate-Specific Membrane Antigen PET/CT in Triple-Negative Breast Cancer.

PubMed

Passah, Averilicia; Arora, Saurabh; Damle, Nishikant Avinash; Tripathi, Madhavi; Bal, Chandrasekhar; Subudhi, T Kishan; Arora, Geetanjali

2018-06-01

The prostate-specific membrane antigen (PSMA) is a transmembrane protein with elevated expression in prostate cancer cells. Breast cancer also shows PSMA expression. We present the case of a 30-year-old woman with triple-negative bilateral breast carcinoma who underwent bilateral mastectomy, chemotherapy, and radiotherapy. She developed a left chest wall and liver recurrence after primary therapy. Her recurrent disease was also triple-negative. In view of the known poor prognosis and very limited therapeutic options, we performed Ga-PSMA PET/CT scan to explore the possibility of PSMA-based therapy as a future option after exhausting standard-of-care treatments.

Craniospinal Irradiation for Trilateral Retinoblastoma Following Ocular Irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marks, Lawrence B.; Bentel, Gunilla; Sherouse, George W.

A case study is presented. Craniospinal radiotherapy and a three-field pineal boost for trilateral retinoblastoma were delivered to a patient previously irradiated for ocular retinoblastoma. The availability of CT-based three-dimensional treatment planning provided the capability of identifying the previously irradiated volume as a three-dimensional anatomic structure and of designing a highly customized set of treatment beams that minimized reirradiation of that volume.

A hybrid approach for fusing 4D-MRI temporal information with 3D-CT for the study of lung and lung tumor motion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Y. X.; Van Reeth, E.; Poh, C. L., E-mail: clpoh@ntu.edu.sg

2015-08-15

Purpose: Accurate visualization of lung motion is important in many clinical applications, such as radiotherapy of lung cancer. Advancement in imaging modalities [e.g., computed tomography (CT) and MRI] has allowed dynamic imaging of lung and lung tumor motion. However, each imaging modality has its advantages and disadvantages. The study presented in this paper aims at generating synthetic 4D-CT dataset for lung cancer patients by combining both continuous three-dimensional (3D) motion captured by 4D-MRI and the high spatial resolution captured by CT using the authors’ proposed approach. Methods: A novel hybrid approach based on deformable image registration (DIR) and finite elementmore » method simulation was developed to fuse a static 3D-CT volume (acquired under breath-hold) and the 3D motion information extracted from 4D-MRI dataset, creating a synthetic 4D-CT dataset. Results: The study focuses on imaging of lung and lung tumor. Comparing the synthetic 4D-CT dataset with the acquired 4D-CT dataset of six lung cancer patients based on 420 landmarks, accurate results (average error <2 mm) were achieved using the authors’ proposed approach. Their hybrid approach achieved a 40% error reduction (based on landmarks assessment) over using only DIR techniques. Conclusions: The synthetic 4D-CT dataset generated has high spatial resolution, has excellent lung details, and is able to show movement of lung and lung tumor over multiple breathing cycles.« less

A dual model HU conversion from MRI intensity values within and outside of bone segment for MRI-based radiotherapy treatment planning of prostate cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Korhonen, Juha, E-mail: juha.p.korhonen@hus.fi; Department of Oncology, Helsinki University Central Hospital, POB-180, 00029 HUS; Kapanen, Mika

2014-01-15

Purpose: The lack of electron density information in magnetic resonance images (MRI) poses a major challenge for MRI-based radiotherapy treatment planning (RTP). In this study the authors convert MRI intensity values into Hounsfield units (HUs) in the male pelvis and thus enable accurate MRI-based RTP for prostate cancer patients with varying tissue anatomy and body fat contents. Methods: T{sub 1}/T{sub 2}*-weighted MRI intensity values and standard computed tomography (CT) image HUs in the male pelvis were analyzed using image data of 10 prostate cancer patients. The collected data were utilized to generate a dual model HU conversion technique from MRImore » intensity values of the single image set separately within and outside of contoured pelvic bones. Within the bone segment local MRI intensity values were converted to HUs by applying a second-order polynomial model. This model was tuned for each patient by two patient-specific adjustments: MR signal normalization to correct shifts in absolute intensity level and application of a cutoff value to accurately represent low density bony tissue HUs. For soft tissues, such as fat and muscle, located outside of the bone contours, a threshold-based segmentation method without requirements for any patient-specific adjustments was introduced to convert MRI intensity values into HUs. The dual model HU conversion technique was implemented by constructing pseudo-CT images for 10 other prostate cancer patients. The feasibility of these images for RTP was evaluated by comparing HUs in the generated pseudo-CT images with those in standard CT images, and by determining deviations in MRI-based dose distributions compared to those in CT images with 7-field intensity modulated radiation therapy (IMRT) with the anisotropic analytical algorithm and 360° volumetric-modulated arc therapy (VMAT) with the Voxel Monte Carlo algorithm. Results: The average HU differences between the constructed pseudo-CT images and standard CT images of each test patient ranged from −2 to 5 HUs and from 22 to 78 HUs in soft and bony tissues, respectively. The average local absolute value differences were 11 HUs in soft tissues and 99 HUs in bones. The planning target volume doses (volumes 95%, 50%, 5%) in the pseudo-CT images were within 0.8% compared to those in CT images in all of the 20 treatment plans. The average deviation was 0.3%. With all the test patients over 94% (IMRT) and 92% (VMAT) of dose points within body (lower than 10% of maximum dose suppressed) passed the 1 mm and 1% 2D gamma index criterion. The statistical tests (t- and F-tests) showed significantly improved (p ≤ 0.05) HU and dose calculation accuracies with the soft tissue conversion method instead of homogeneous representation of these tissues in MRI-based RTP images. Conclusions: This study indicates that it is possible to construct high quality pseudo-CT images by converting the intensity values of a single MRI series into HUs in the male pelvis, and to use these images for accurate MRI-based prostate RTP dose calculations.« less

Validation of a personalized dosimetric evaluation tool (Oedipe) for targeted radiotherapy based on the Monte Carlo MCNPX code

NASA Astrophysics Data System (ADS)

Chiavassa, S.; Aubineau-Lanièce, I.; Bitar, A.; Lisbona, A.; Barbet, J.; Franck, D.; Jourdain, J. R.; Bardiès, M.

2006-02-01

Dosimetric studies are necessary for all patients treated with targeted radiotherapy. In order to attain the precision required, we have developed Oedipe, a dosimetric tool based on the MCNPX Monte Carlo code. The anatomy of each patient is considered in the form of a voxel-based geometry created using computed tomography (CT) images or magnetic resonance imaging (MRI). Oedipe enables dosimetry studies to be carried out at the voxel scale. Validation of the results obtained by comparison with existing methods is complex because there are multiple sources of variation: calculation methods (different Monte Carlo codes, point kernel), patient representations (model or specific) and geometry definitions (mathematical or voxel-based). In this paper, we validate Oedipe by taking each of these parameters into account independently. Monte Carlo methodology requires long calculation times, particularly in the case of voxel-based geometries, and this is one of the limits of personalized dosimetric methods. However, our results show that the use of voxel-based geometry as opposed to a mathematically defined geometry decreases the calculation time two-fold, due to an optimization of the MCNPX2.5e code. It is therefore possible to envisage the use of Oedipe for personalized dosimetry in the clinical context of targeted radiotherapy.

Competing-risks mortality after radiotherapy vs. observation for localized prostate cancer: a population-based study.

PubMed

Abdollah, Firas; Sun, Maxine; Schmitges, Jan; Thuret, Rodolphe; Tian, Zhe; Shariat, Shahrokh F; Briganti, Alberto; Jeldres, Claudio; Perrotte, Paul; Montorsi, Francesco; Karakiewicz, Pierre I

2012-09-01

Contemporary patients with localized prostate cancer (PCa) are more frequently treated with radiotherapy. However, there are limited data on the effect of this treatment on cancer-specific mortality (CSM). Our objective was to test the relationship between radiotherapy and survival in men with localized PCa and compare it with those treated with observation. A population-based cohort identified 68,797 men with cT1-T2 PCa treated with radiotherapy or observation between the years 1992 and 2005. Propensity-score matching was used to minimize potential bias related to treatment assignment. Competing-risks analyses tested the effect of treatment type (radiotherapy vs. observation) on CSM, after accounting to other-cause mortality. All analyses were carried out within PCa risk, baseline comorbidity status, and age groups. Radiotherapy was associated with more favorable 10-year CSM rates than observation in patients with high-risk PCa (8.8 vs. 14.4%, hazard ratio [HR]: 0.59, 95% confidence interval [CI]: 0.50-0.68). Conversely, the beneficial effect of radiotherapy on CSM was not evident in patients with low-intermediate risk PCa (3.7 vs. 4.1%, HR: 0.91, 95% CI: 0.80-1.04). Radiotherapy was beneficial in elderly patients (5.6 vs. 7.3%, HR: 0.70, 95% CI: 0.59-0.80). Moreover, it was associated with improved CSM rates among patients with no comorbidities (5.7 vs. 6.5%, HR: 0.81, 95% CI: 0.67-0.98), one comorbidity (4.6 vs. 6.0%, HR: 0.87, 95% CI: 0.75-0.99), and more than two comorbidities (4.2 vs. 5.0%, HR: 0.79, 95% CI: 0.65-0.96). Radiotherapy substantially improves CSM in patients with high-risk PCa, with little or no benefit in patients with low-/intermediate-risk PCa relative to observation. These findings must be interpreted within the context of the limitations of observational data. Copyright © 2012 Elsevier Inc. All rights reserved.

SU-E-T-261: Development of An Automated System to Detect Patient Identification and Positioning Errors Prior to Radiotherapy Treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jani, S; Low, D; Lamb, J

2015-06-15

Purpose: To develop a system that can automatically detect patient identification and positioning errors using 3D computed tomography (CT) setup images and kilovoltage CT (kVCT) planning images. Methods: Planning kVCT images were collected for head-and-neck (H&N), pelvis, and spine treatments with corresponding 3D cone-beam CT (CBCT) and megavoltage CT (MVCT) setup images from TrueBeam and TomoTherapy units, respectively. Patient identification errors were simulated by registering setup and planning images from different patients. Positioning errors were simulated by misaligning the setup image by 1cm to 5cm in the six anatomical directions for H&N and pelvis patients. Misalignments for spine treatments weremore » simulated by registering the setup image to adjacent vertebral bodies on the planning kVCT. A body contour of the setup image was used as an initial mask for image comparison. Images were pre-processed by image filtering and air voxel thresholding, and image pairs were assessed using commonly-used image similarity metrics as well as custom -designed metrics. A linear discriminant analysis classifier was trained and tested on the datasets, and misclassification error (MCE), sensitivity, and specificity estimates were generated using 10-fold cross validation. Results: Our workflow produced MCE estimates of 0.7%, 1.7%, and 0% for H&N, pelvis, and spine TomoTherapy images, respectively. Sensitivities and specificities ranged from 98.0% to 100%. MCEs of 3.5%, 2.3%, and 2.1% were obtained for TrueBeam images of the above sites, respectively, with sensitivity and specificity estimates between 96.2% and 98.4%. MCEs for 1cm H&N/pelvis misalignments were 1.3/5.1% and 9.1/8.6% for TomoTherapy and TrueBeam images, respectively. 2cm MCE estimates were 0.4%/1.6% and 3.1/3.2%, respectively. Vertebral misalignment MCEs were 4.8% and 4.9% for TomoTherapy and TrueBeam images, respectively. Conclusion: Patient identification and gross misalignment errors can be robustly and automatically detected using 3D setup images of two imaging modalities across three commonly-treated anatomical sites.« less

Phase II Trial of Combined High-Dose-Rate Brachytherapy and External Beam Radiotherapy for Adenocarcinoma of the Prostate: Preliminary Results of RTOG 0321

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsu, I-Chow, E-mail: ihsu@radonc.ucsf.ed; Bae, Kyounghwa; Shinohara, Katsuto

2010-11-01

Purpose: To estimate the rate of late Grade 3 or greater genitourinary (GU) and gastrointestinal (GI) adverse events (AEs) after treatment with external beam radiotherapy and prostate high-dose-rate (HDR) brachytherapy. Methods and Materials: Each participating institution submitted computed tomography-based HDR brachytherapy dosimetry data electronically for credentialing and for each study patient. Patients with locally confined Stage T1c-T3b prostate cancer were eligible for the present study. All patients were treated with 45 Gy in 25 fractions using external beam radiotherapy and one HDR implant delivering 19 Gy in two fractions. All AEs were graded according to the Common Terminology Criteria formore » Adverse Events, version 3.0. Late GU/GI AEs were defined as those occurring >9 months from the start of the protocol treatment, in patients with {>=}18 months of potential follow-up. Results: A total of 129 patients from 14 institutions were enrolled in the present study. Of the 129 patients, 125 were eligible, and AE data were available for 112 patients at analysis. The pretreatment characteristics of the patients were as follows: Stage T1c-T2c, 91%; Stage T3a-T3b, 9%; prostate-specific antigen level {<=}10 ng/mL, 70%; prostate-specific antigen level >10 but {<=}20 ng/mL, 30%; and Gleason score 2-6, 10%; Gleason score 7, 72%; and Gleason score 8-10, 18%. At a median follow-up of 29.6 months, three acute and four late Grade 3 GU/GI AEs were reported. The estimated rate of late Grade 3-5 GU and GI AEs at 18 months was 2.56%. Conclusion: This is the first prospective, multi-institutional trial of computed tomography-based HDR brachytherapy and external beam radiotherapy. The technique and doses used in the present study resulted in acceptable levels of AEs.« less

Characterization of 'cold' vertebrae on 18F-FDG PET/CT.

PubMed

Jaimini, Abhinav; D'Souza, Maria M; Seniaray, Nikhil; Sharma, Harshul; Arbind, Arpana; Sharma, Rajnish; Mondal, Anupam

2016-01-01

A photon-deficient ('cold') vertebra on fluorine-18 fluorodeoxyglucose (F-FDG) PET is a known entity and can arise as a result of varying etiologies. A proper interpretation of this observation is required to make an accurate diagnosis for appropriate management. Twelve cases with 'cold' vertebrae on F-FDG PET/computed tomography (CT) were selected and analyzed from a population of 600 patients with a known malignancy who had undergone whole-body F-FDG PET/CT for staging, disease viability assessment, response to treatment, or suspected recurrence purposes. The patterns were studied and correlated with clinical history and the results of the low-dose CT performed with the PET scan for attenuation correction and anatomical localization. The most common cause for cold vertebrae was found to be postexternal radiotherapy, causing photopenia involving multiple vertebrae corresponding to the radiotherapy portals. Two other causes found in the study were the destruction of the vertebral marrow cavity by metastatic tumor cells and vertebral hemangioma. Characteristic features of 'cold' vertebrae have been described in the study with illustrations. Pattern recognition coupled with clinical history and CT correlation of 'cold' vertebrae on F-FDG PET/CT can help in diagnosing the correct underlying etiology, which can help in better management of the patients.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Haksoo; Welford, Scott; Fabien, Jeffrey

Purpose: Establish and validate a process of accurately irradiating small animals using the CyberKnife G4 System (version 8.5) with treatment plans designed to irradiate a hemisphere of a mouse brain based on microCT scanner images. Methods: These experiments consisted of four parts: (1) building a mouse phantom for intensity modulated radiotherapy (IMRT) quality assurance (QA), (2) proving usability of a microCT for treatment planning, (3) fabricating a small animal positioning system for use with the CyberKnife's image guided radiotherapy (IGRT) system, and (4)in vivo verification of targeting accuracy. A set of solid water mouse phantoms was designed and fabricated, withmore » radiochromic films (RCF) positioned in selected planes to measure delivered doses. After down-sampling for treatment planning compatibility, a CT image set of a phantom was imported into the CyberKnife treatment planning system—MultiPlan (ver. 3.5.2). A 0.5 cm diameter sphere was contoured within the phantom to represent a hemispherical section of a mouse brain. A nude mouse was scanned in an alpha cradle using a microCT scanner (cone-beam, 157 × 149 pixels slices, 0.2 mm longitudinal slice thickness). Based on the results of our positional accuracy study, a planning treatment volume (PTV) was created. A stereotactic body mold of the mouse was “printed” using a 3D printer laying UV curable acrylic plastic. Printer instructions were based on exported contours of the mouse's skin. Positional reproducibility in the mold was checked by measuring ten CT scans. To verify accurate dose delivery in vivo, six mice were irradiated in the mold with a 4 mm target contour and a 2 mm PTV margin to 3 Gy and sacrificed within 20 min to avoid DNA repair. The brain was sliced and stained for analysis. Results: For the IMRT QA using a set of phantoms, the planned dose (6 Gy to the calculation point) was compared to the delivered dose measured via film and analyzed using Gamma analysis (3% and 3 mm). A passing rate of 99% was measured in areas of above 40% of the prescription dose. The final inverse treatment plan was comprised of 43 beams ranging from 5 to 12.5 mm in diameter (2.5 mm size increments are available up to 15 mm in diameter collimation). Using the Xsight Spine Tracking module, the CyberKnife system could not reliably identify and track the tiny mouse spine; however, the CyberKnife system could identify and track the fiducial markers on the 3D mold.In vivo positional accuracy analysis using the 3D mold generated a mean error of 1.41 mm ± 0.73 mm when fiducial markers were used for position tracking. Analysis of the dissected brain confirmed the ability to target the correct brain volume. Conclusions: With the use of a stereotactic body mold with fiducial markers, microCT imaging, and resolution down-sampling, the CyberKnife system can successfully perform small-animal radiotherapy studies.« less

A New Era of Image Guidance with Magnetic Resonance-guided Radiation Therapy for Abdominal and Thoracic Malignancies

PubMed Central

Paliwal, Bhudatt; Hill, Patrick; Bayouth, John E; Geurts, Mark W; Baschnagel, Andrew M; Bradley, Kristin A; Harari, Paul M; Rosenberg, Stephen; Brower, Jeffrey V; Wojcieszynski, Andrzej P; Hullett, Craig; Bayliss, R A; Labby, Zacariah E; Bassetti, Michael F

2018-01-01

Magnetic resonance-guided radiation therapy (MRgRT) offers advantages for image guidance for radiotherapy treatments as compared to conventional computed tomography (CT)-based modalities. The superior soft tissue contrast of magnetic resonance (MR) enables an improved visualization of the gross tumor and adjacent normal tissues in the treatment of abdominal and thoracic malignancies. Online adaptive capabilities, coupled with advanced motion management of real-time tracking of the tumor, directly allow for high-precision inter-/intrafraction localization. The primary aim of this case series is to describe MR-based interventions for localizing targets not well-visualized with conventional image-guided technologies. The abdominal and thoracic sites of the lung, kidney, liver, and gastric targets are described to illustrate the technological advancement of MR-guidance in radiotherapy. PMID:29872602

Ontology for heart rate turbulence domain from the conceptual model of SNOMED-CT.

PubMed

Soguero-Ruiz, Cristina; Lechuga-Suárez, Luis; Mora-Jiménez, Inmaculada; Ramos-López, Javier; Barquero-Pérez, Óscar; García-Alberola, Arcadi; Rojo-Álvarez, José L

2013-07-01

Electronic health record (EHR) automates the clinician workflow, allowing evidence-based decision support and quality management. We aimed to start a framework for domain standardization of cardiovascular risk stratification into the EHR, including risk indices whose calculation involves ECG signal processing. We propose the use of biomedical ontologies completely based on the conceptual model of SNOMED-CT, which allows us to implement our domain in the EHR. In this setting, the present study focused on the heart rate turbulence (HRT) domain, according to its concise guidelines and clear procedures for parameter calculations. We used 289 concepts from SNOMED-CT, and generated 19 local extensions (new concepts) for the HRT specific concepts not present in the current version of SNOMED-CT. New concepts included averaged and individual ventricular premature complex tachograms, initial sinus acceleration for turbulence onset, or sinusal oscillation for turbulence slope. Two representative use studies were implemented: first, a prototype was inserted in the hospital information system for supporting HRT recordings and their simple follow up by medical societies; second, an advanced support for a prospective scientific research, involving standard and emergent signal processing algorithms in the HRT indices, was generated and then tested in an example database of 27 Holter patients. Concepts of the proposed HRT ontology are publicly available through a terminology server, hence their use in any information system will be straightforward due to the interoperability provided by SNOMED-CT.

Establishing a process of irradiating small animal brain using a CyberKnife and a microCT scanner

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Haksoo; Welford, Scott; Fabien, Jeffrey

2014-02-15

Purpose: Establish and validate a process of accurately irradiating small animals using the CyberKnife G4 System (version 8.5) with treatment plans designed to irradiate a hemisphere of a mouse brain based on microCT scanner images. Methods: These experiments consisted of four parts: (1) building a mouse phantom for intensity modulated radiotherapy (IMRT) quality assurance (QA), (2) proving usability of a microCT for treatment planning, (3) fabricating a small animal positioning system for use with the CyberKnife's image guided radiotherapy (IGRT) system, and (4)in vivo verification of targeting accuracy. A set of solid water mouse phantoms was designed and fabricated, withmore » radiochromic films (RCF) positioned in selected planes to measure delivered doses. After down-sampling for treatment planning compatibility, a CT image set of a phantom was imported into the CyberKnife treatment planning system—MultiPlan (ver. 3.5.2). A 0.5 cm diameter sphere was contoured within the phantom to represent a hemispherical section of a mouse brain. A nude mouse was scanned in an alpha cradle using a microCT scanner (cone-beam, 157 × 149 pixels slices, 0.2 mm longitudinal slice thickness). Based on the results of our positional accuracy study, a planning treatment volume (PTV) was created. A stereotactic body mold of the mouse was “printed” using a 3D printer laying UV curable acrylic plastic. Printer instructions were based on exported contours of the mouse's skin. Positional reproducibility in the mold was checked by measuring ten CT scans. To verify accurate dose delivery in vivo, six mice were irradiated in the mold with a 4 mm target contour and a 2 mm PTV margin to 3 Gy and sacrificed within 20 min to avoid DNA repair. The brain was sliced and stained for analysis. Results: For the IMRT QA using a set of phantoms, the planned dose (6 Gy to the calculation point) was compared to the delivered dose measured via film and analyzed using Gamma analysis (3% and 3 mm). A passing rate of 99% was measured in areas of above 40% of the prescription dose. The final inverse treatment plan was comprised of 43 beams ranging from 5 to 12.5 mm in diameter (2.5 mm size increments are available up to 15 mm in diameter collimation). Using the Xsight Spine Tracking module, the CyberKnife system could not reliably identify and track the tiny mouse spine; however, the CyberKnife system could identify and track the fiducial markers on the 3D mold.In vivo positional accuracy analysis using the 3D mold generated a mean error of 1.41 mm ± 0.73 mm when fiducial markers were used for position tracking. Analysis of the dissected brain confirmed the ability to target the correct brain volume. Conclusions: With the use of a stereotactic body mold with fiducial markers, microCT imaging, and resolution down-sampling, the CyberKnife system can successfully perform small-animal radiotherapy studies.« less

Moving toward uniform and evidence-based practice of radiotherapy for management of cervical cancer in Ontario, Canada.

PubMed

Shahid, Negin; Craig, Timothy; Westerland, Mary; Ashworth, Allison; Ang, Michelle; D'Souza, David; Sankreacha, Raxa; Fyles, Anthony; Milosevic, Michael; Kong, Iwa

2018-04-19

To recognize the practice of radiotherapy for management of cervical cancer in Ontario, Canada, and to use the results of the survey to harmonize and standardize practice across the province. An electronic survey (SurveyMonkey) was sent to all 14 provincial cancer centers by Cancer Care Ontario Gynecology Community of Practice (CoP) in 2013. The survey included 72 questions in four different categories: general/demographic, pretreatment assessment, external beam radiotherapy (EBRT), and brachytherapy (BT). Ten of 14 centers treated cervical cancer patients and had a dedicated BT suite. All 10 centers had a peer review process for quality assurance. EBRT technique was a 4-field box in eight of 10 centers. The dose/fractionation for pelvic EBRT was 45-50 Gy in 1.8-2 Gy/fraction in all but one center. Nine of 10 centers used high-dose-rate BT. Only one center offered interstitial BT. For treatment planning, two centers used CT and MRI, five centers used CT, and three centers used orthogonal x-rays. Groupe Européen de Curiethérapie and the European Society for Radiotherapy & Oncology guidelines were used in four of seven of the centers for target volume delineation and in five of seven centers for organs at risk dose constraints. All but one center prescribed and reported dose to Point A. The survey identified areas where practice varied across the province. Gynecology CoP used this information to identify priorities for practice change and implemented several strategies to harmonize the care of women with cervical cancer. This highlights the value of interdisciplinary, grass-roots initiatives such as CoPs to standardize practice in a practical manner that directly benefits patients. Copyright © 2018 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Prediction of radiation-induced normal tissue complications in radiotherapy using functional image data

NASA Astrophysics Data System (ADS)

Nioutsikou, Elena; Partridge, Mike; Bedford, James L.; Webb, Steve

2005-03-01

The aim of this study has been to explicitly include the functional heterogeneity of an organ as a factor that contributes to the probability of complication of normal tissues following radiotherapy. Situations for which the inclusion of this information can be advantageous to the design of treatment plans are then investigated. A Java program has been implemented for this purpose. This makes use of a voxelated model of a patient, which is based on registered anatomical and functional data in order to enable functional voxel weighting. Using this model, the functional dose-volume histogram (fDVH) and the functional normal tissue complication probability (fNTCP) are then introduced as extensions to the conventional dose-volume histogram (DVH) and normal tissue complication probability (NTCP). In the presence of functional heterogeneity, these tools are physically more meaningful for plan evaluation than the traditional indices, as they incorporate additional information and are anticipated to show a better correlation with outcome. New parameters mf, nf and TD50f are required to replace the m, n and TD50 parameters. A range of plausible values was investigated, awaiting fitting of these new parameters to patient outcomes where functional data have been measured. As an example, the model is applied to two lung datasets utilizing accurately registered computed tomography (CT) and single photon emission computed tomography (SPECT) perfusion scans. Assuming a linear perfusion-function relationship, the biological index mean perfusion weighted lung dose (MPWLD) has been extracted from integration over outlined regions of interest. In agreement with the MPWLD ranking, the fNTCP predictions reveal that incorporation of functional imaging in radiotherapy treatment planning is most beneficial for organs with a large volume effect and large focal areas of dysfunction. There is, however, no additional advantage in cases presenting with homogeneous function. Although presented for lung radiotherapy, this model is general. It can also be applied to positron emission tomography (PET)-CT or functional magnetic resonance imaging (fMRI)-CT registered data and extended to the functional description of tumour control probability.

The potential advantages of (18)FDG PET/CT-based target volume delineation in radiotherapy planning of head and neck cancer.

PubMed

Moule, Russell N; Kayani, Irfan; Moinuddin, Syed A; Meer, Khalda; Lemon, Catherine; Goodchild, Kathleen; Saunders, Michele I

2010-11-01

This study investigated two fixed threshold methods to delineate the target volume using (18)FDG PET/CT before and during a course of radical radiotherapy in locally advanced squamous cell carcinoma of the head and neck. Patients were enrolled into the study between March 2006 and May 2008. (18)FDG PET/CT scans were carried out 72h prior to the start of radiotherapy and then at 10, 44 and 66Gy. Functional volumes were delineated according to the SUV Cut Off (SUVCO) (2.5, 3.0, 3.5, and 4.0bwg/ml) and percentage of the SUVmax (30%, 35%, 40%, 45%, and 50%) thresholds. The background (18)FDG uptake and the SUVmax within the volumes were also assessed. Primary and lymph node volumes for the eight patients significantly reduced with each increase in the delineation threshold (for example 2.5-3.0bwg/ml SUVCO) compared to the baseline threshold at each imaging point. There was a significant reduction in the volume (p⩽0.0001-0.01) after 36Gy compared to the 0Gy by the SUVCO method. There was a negative correlation between the SUVmax within the primary and lymph node volumes and delivered radiation dose (p⩽0.0001-0.011) but no difference in the SUV within the background reference region. The volumes delineated by the PTSUVmax method increased with the increase in the delivered radiation dose after 36Gy because the SUVmax within the region of interest used to define the edge of the volume was equal or less than the background (18)FDG uptake and the software was unable to effectively differentiate between tumour and background uptake. The changes in the target volumes delineated by the SUVCO method were less susceptible to background (18)FDG uptake compared to those delineated by the PTSUVmax and may be more helpful in radiotherapy planning. The best method and threshold have still to be determined within institutions, both nationally and internationally. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

WE-AB-207A-08: BEST IN PHYSICS (IMAGING): Advanced Scatter Correction and Iterative Reconstruction for Improved Cone-Beam CT Imaging On the TrueBeam Radiotherapy Machine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, A; Paysan, P; Brehm, M

2016-06-15

Purpose: To improve CBCT image quality for image-guided radiotherapy by applying advanced reconstruction algorithms to overcome scatter, noise, and artifact limitations Methods: CBCT is used extensively for patient setup in radiotherapy. However, image quality generally falls short of diagnostic CT, limiting soft-tissue based positioning and potential applications such as adaptive radiotherapy. The conventional TrueBeam CBCT reconstructor uses a basic scatter correction and FDK reconstruction, resulting in residual scatter artifacts, suboptimal image noise characteristics, and other artifacts like cone-beam artifacts. We have developed an advanced scatter correction that uses a finite-element solver (AcurosCTS) to model the behavior of photons as theymore » pass (and scatter) through the object. Furthermore, iterative reconstruction is applied to the scatter-corrected projections, enforcing data consistency with statistical weighting and applying an edge-preserving image regularizer to reduce image noise. The combined algorithms have been implemented on a GPU. CBCT projections from clinically operating TrueBeam systems have been used to compare image quality between the conventional and improved reconstruction methods. Planning CT images of the same patients have also been compared. Results: The advanced scatter correction removes shading and inhomogeneity artifacts, reducing the scatter artifact from 99.5 HU to 13.7 HU in a typical pelvis case. Iterative reconstruction provides further benefit by reducing image noise and eliminating streak artifacts, thereby improving soft-tissue visualization. In a clinical head and pelvis CBCT, the noise was reduced by 43% and 48%, respectively, with no change in spatial resolution (assessed visually). Additional benefits include reduction of cone-beam artifacts and reduction of metal artifacts due to intrinsic downweighting of corrupted rays. Conclusion: The combination of an advanced scatter correction with iterative reconstruction substantially improves CBCT image quality. It is anticipated that clinically acceptable reconstruction times will result from a multi-GPU implementation (the algorithms are under active development and not yet commercially available). All authors are employees of and (may) own stock of Varian Medical Systems.« less

SU-E-J-210: Characterizing Tissue Equivalent Materials for the Development of a Dual MRI-CT Heterogeneous Anthropomorphic Phantom Designed Specifically for MRI Guided Radiotherapy Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steinmann, A; Stafford, R; Yung, J

Purpose: MRI guided radiotherapy (MRIgRT) is an emerging technology which will eventually require a proficient quality auditing system. Due to different principles in which MR and CT acquire images, there is a need for a multi-imaging-modality, end-to-end QA phantom for MRIgRT. The purpose of this study is to identify lung, soft tissue, and tumor equivalent substitutes that share similar human-like CT and MR properties (i.e. Hounsfield units and relaxation times). Methods: Materials of interested such as common CT QA phantom materials, and other proprietary gels/silicones from Polytek, SmoothOn, and CompositeOne were first scanned on a GE 1.5T Signa HDxT MR.more » Materials that could be seen on both T1-weighted and T2-weighted images were then scanned on a GE Lightspeed RT16 CT simulator and a GE Discovery 750HD CT scanner and their HU values were then measured. The materials with matching HU values of lung (−500 to −700HU), muscle (+40HU) and soft tissue (+100 to +300HU) were further scanned on GE 1.5T Signa HDx to measure their T1 and T2 relaxation times from varying parameters of TI and TE. Results: Materials that could be visualized on T1-weighted and T2-weighted images from a 1.5T MR unit and had an appropriate average CT number, −650, −685, 46,169, and 168 HUs were: compressed cork saturated with water, Polytek Platsil™ Gel-00 combined with mini styrofoam balls, radiotherapy bolus material, SmoothOn Dragon-Skin™ and SmoothOn Ecoflex™, respectively. Conclusion: Post processing analysis is currently being performed to accurately map T1 and T2 values for each material tested. From previous MR visualization and CT examinations it is expected that Dragon-Skin™, Ecoflex™ and bolus will have values consistent with tissue and tumor substitutes. We also expect compressed cork statured with water, and Polytek™-styrofoam combination to have approximate T1 and T2 values suitable for lung-equivalent materials.« less

Influence of FDG-PET on primary nodal target volume definition for head and neck carcinomas.

PubMed

van Egmond, Sylvia L; Piscaer, Vera; Janssen, Luuk M; Stegeman, Inge; Hobbelink, Monique G; Grolman, Wilko; Terhaard, Chris H

The role of 2-[ 18 F]-fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET)/computed tomography (CT) in routine diagnostic staging remains controversial. In case of discordance between FDG-PET and CT, a compromise has to be made between the risk of false positive FDG-PET and the risk of delaying appropriate salvage intervention. Second, with intensity modulated radiation therapy (IMRT), smaller radiation fields allow tissue sparing, but could also lead to more marginal failures. We retrospectively studied 283 patients with head and neck carcinoma scheduled for radiotherapy between 2002 and 2010. We analyzed the influence of FDG-PET/CT versus CT alone on defining nodal target volume definition and evaluated its long-term clinical results. Second, the location of nodal recurrences was related to the radiation regional dose distribution. In 92 patients, CT and FDG-PET, performed in mold, showed discordant results. In 33%, nodal staging was altered by FDG-PET. In 24%, FDG-PET also led to an alteration in nodal treatment, including a nodal upstage of 18% and downstage of 6%. In eight of these 92 patients, a regional recurrence occurred. Only two patients had a recurrence in the discordant node on FDG-PET and CT and both received a boost (high dose radiation). These results support the complementary value of FDG-PET/CT compared to CT alone in defining nodal target volume definition for radiotherapy of head and neck cancer.

Augmenting atlas-based liver segmentation for radiotherapy treatment planning by incorporating image features proximal to the atlas contours

NASA Astrophysics Data System (ADS)

Li, Dengwang; Liu, Li; Chen, Jinhu; Li, Hongsheng; Yin, Yong; Ibragimov, Bulat; Xing, Lei

2017-01-01

Atlas-based segmentation utilizes a library of previously delineated contours of similar cases to facilitate automatic segmentation. The problem, however, remains challenging because of limited information carried by the contours in the library. In this studying, we developed a narrow-shell strategy to enhance the information of each contour in the library and to improve the accuracy of the exiting atlas-based approach. This study presented a new concept of atlas based segmentation method. Instead of using the complete volume of the target organs, only information along the organ contours from the atlas images was used for guiding segmentation of the new image. In setting up an atlas-based library, we included not only the coordinates of contour points, but also the image features adjacent to the contour. In this work, 139 CT images with normal appearing livers collected for radiotherapy treatment planning were used to construct the library. The CT images within the library were first registered to each other using affine registration. The nonlinear narrow shell was generated alongside the object contours of registered images. Matching voxels were selected inside common narrow shell image features of a library case and a new case using a speed-up robust features (SURF) strategy. A deformable registration was then performed using a thin plate splines (TPS) technique. The contour associated with the library case was propagated automatically onto the new image by exploiting the deformation field vectors. The liver contour was finally obtained by employing level set based energy optimization within the narrow shell. The performance of the proposed method was evaluated by comparing quantitatively the auto-segmentation results with that delineated by physicians. A novel atlas-based segmentation technique with inclusion of neighborhood image features through the introduction of a narrow-shell surrounding the target objects was established. Application of the technique to 30 liver cases suggested that the technique was capable to reliably segment liver cases from CT, 4D-CT, and CBCT images with little human interaction. The accuracy and speed of the proposed method are quantitatively validated by comparing automatic segmentation results with the manual delineation results. The Jaccard similarity metric between the automatically generated liver contours obtained by the proposed method and the physician delineated results are on an average 90%-96% for planning images. Incorporation of image features into the library contours improves the currently available atlas-based auto-contouring techniques and provides a clinically practical solution for auto-segmentation. The proposed mountainous narrow shell atlas based method can achieve efficient automatic liver propagation for CT, 4D-CT and CBCT images with following treatment planning and should find widespread application in future treatment planning systems.

Augmenting atlas-based liver segmentation for radiotherapy treatment planning by incorporating image features proximal to the atlas contours.

PubMed

Li, Dengwang; Liu, Li; Chen, Jinhu; Li, Hongsheng; Yin, Yong; Ibragimov, Bulat; Xing, Lei

2017-01-07

Atlas-based segmentation utilizes a library of previously delineated contours of similar cases to facilitate automatic segmentation. The problem, however, remains challenging because of limited information carried by the contours in the library. In this studying, we developed a narrow-shell strategy to enhance the information of each contour in the library and to improve the accuracy of the exiting atlas-based approach. This study presented a new concept of atlas based segmentation method. Instead of using the complete volume of the target organs, only information along the organ contours from the atlas images was used for guiding segmentation of the new image. In setting up an atlas-based library, we included not only the coordinates of contour points, but also the image features adjacent to the contour. In this work, 139 CT images with normal appearing livers collected for radiotherapy treatment planning were used to construct the library. The CT images within the library were first registered to each other using affine registration. The nonlinear narrow shell was generated alongside the object contours of registered images. Matching voxels were selected inside common narrow shell image features of a library case and a new case using a speed-up robust features (SURF) strategy. A deformable registration was then performed using a thin plate splines (TPS) technique. The contour associated with the library case was propagated automatically onto the new image by exploiting the deformation field vectors. The liver contour was finally obtained by employing level set based energy optimization within the narrow shell. The performance of the proposed method was evaluated by comparing quantitatively the auto-segmentation results with that delineated by physicians. A novel atlas-based segmentation technique with inclusion of neighborhood image features through the introduction of a narrow-shell surrounding the target objects was established. Application of the technique to 30 liver cases suggested that the technique was capable to reliably segment liver cases from CT, 4D-CT, and CBCT images with little human interaction. The accuracy and speed of the proposed method are quantitatively validated by comparing automatic segmentation results with the manual delineation results. The Jaccard similarity metric between the automatically generated liver contours obtained by the proposed method and the physician delineated results are on an average 90%-96% for planning images. Incorporation of image features into the library contours improves the currently available atlas-based auto-contouring techniques and provides a clinically practical solution for auto-segmentation. The proposed mountainous narrow shell atlas based method can achieve efficient automatic liver propagation for CT, 4D-CT and CBCT images with following treatment planning and should find widespread application in future treatment planning systems.

Combined use of (18)F-FDG and (18)F-FMISO in unresectable non-small cell lung cancer patients planned for radiotherapy: a dynamic PET/CT study.

PubMed

Sachpekidis, Christos; Thieke, Christian; Askoxylakis, Vasileios; Nicolay, Nils H; Huber, Peter E; Thomas, Michael; Dimitrakopoulou, Georgia; Debus, Juergen; Haberkorn, Uwe; Dimitrakopoulou-Strauss, Antonia

2015-01-01

Aim of this study was to evaluate and compare, by means of dynamic and static PET/CT, the distribution patterns and pharmacokinetics of fluorine-18 fluorodeoxyglucose ((18)F-FDG) and of fluorine-18-fluoromisonidazole ((18)F-FMISO) in non-small cell lung cancer (NSCLC) patients scheduled for intensity modulated radiation therapy (IMRT). Thirteen patients suffering from inoperable stage III NSCLC underwent PET/CTs with (18)F-FDG and (18)F-FMISO for tumor metabolism and hypoxia assessment accordingly. Evaluation of PET/CT studies was based on visual analysis, semi-quantitative (SUV) calculations and absolute quantitative estimations, after application of a two-tissue compartment model and a non-compartmental approach. (18)F-FDG PET/CT revealed all thirteen primary lung tumors as sites of increased (18)F-FDG uptake. Six patients demonstrated also in total 43 (18)F-FDG avid metastases; these patients were excluded from radiotherapy. (18)F-MISO PET/CT demonstrated 12/13 primary lung tumors with faint tracer uptake. Only one tumor was clearly (18)F-FMISO avid, (SUVaverage = 3.4, SUVmax = 5.0). Mean values for (18)F-FDG, as derived from dPET/CT data, were SUVaverage = 8.9, SUVmax = 15.1, K1 = 0.23, k2 = 0.53, k3 = 0.17, k4 = 0.02, influx = 0.05 and fractal dimension (FD) = 1.25 for the primary tumors. The respective values for (18)F-FMISO were SUVaverage = 1.4, SUVmax = 2.2, K1 = 0.26, k2 = 0.56, k3 = 0.06, k4 = 0.06, influx = 0.02 and FD = 1.14. No statistically significant correlation was observed between the two tracers. (18)F-FDG PET/CT changed therapy management in six patients, by excluding them from planned IMRT. (18)F-FMISO PET/CT revealed absence of significant tracer uptake in the majority of the (18)F-FDG avid NSCLCs. Lack of correlation between the two tracers' kinetics indicates that they reflect different molecular mechanisms and implies the discordance between increased glycolysis and hypoxia in the malignancy.

Combined use of 18F-FDG and 18F-FMISO in unresectable non-small cell lung cancer patients planned for radiotherapy: a dynamic PET/CT study

PubMed Central

Sachpekidis, Christos; Thieke, Christian; Askoxylakis, Vasileios; Nicolay, Nils H; Huber, Peter E; Thomas, Michael; Dimitrakopoulou, Georgia; Debus, Juergen; Haberkorn, Uwe; Dimitrakopoulou-Strauss, Antonia

2015-01-01

Aim of this study was to evaluate and compare, by means of dynamic and static PET/CT, the distribution patterns and pharmacokinetics of fluorine-18 fluorodeoxyglucose (18F-FDG) and of fluorine-18-fluoromisonidazole (18F-FMISO) in non-small cell lung cancer (NSCLC) patients scheduled for intensity modulated radiation therapy (IMRT). Thirteen patients suffering from inoperable stage III NSCLC underwent PET/CTs with 18F-FDG and 18F-FMISO for tumor metabolism and hypoxia assessment accordingly. Evaluation of PET/CT studies was based on visual analysis, semi-quantitative (SUV) calculations and absolute quantitative estimations, after application of a two-tissue compartment model and a non-compartmental approach. 18F-FDG PET/CT revealed all thirteen primary lung tumors as sites of increased 18F-FDG uptake. Six patients demonstrated also in total 43 18F-FDG avid metastases; these patients were excluded from radiotherapy. 18F-MISO PET/CT demonstrated 12/13 primary lung tumors with faint tracer uptake. Only one tumor was clearly 18F-FMISO avid, (SUVaverage = 3.4, SUVmax = 5.0). Mean values for 18F-FDG, as derived from dPET/CT data, were SUVaverage = 8.9, SUVmax = 15.1, K1 = 0.23, k2 = 0.53, k3 = 0.17, k4 = 0.02, influx = 0.05 and fractal dimension (FD) = 1.25 for the primary tumors. The respective values for 18F-FMISO were SUVaverage = 1.4, SUVmax = 2.2, K1 = 0.26, k2 = 0.56, k3 = 0.06, k4 = 0.06, influx = 0.02 and FD = 1.14. No statistically significant correlation was observed between the two tracers. 18F-FDG PET/CT changed therapy management in six patients, by excluding them from planned IMRT. 18F-FMISO PET/CT revealed absence of significant tracer uptake in the majority of the 18F-FDG avid NSCLCs. Lack of correlation between the two tracers’ kinetics indicates that they reflect different molecular mechanisms and implies the discordance between increased glycolysis and hypoxia in the malignancy. PMID:25973334

Automatic mediastinal lymph node detection in chest CT

NASA Astrophysics Data System (ADS)

Feuerstein, Marco; Deguchi, Daisuke; Kitasaka, Takayuki; Iwano, Shingo; Imaizumi, Kazuyoshi; Hasegawa, Yoshinori; Suenaga, Yasuhito; Mori, Kensaku

2009-02-01

Computed tomography (CT) of the chest is a very common staging investigation for the assessment of mediastinal, hilar, and intrapulmonary lymph nodes in the context of lung cancer. In the current clinical workflow, the detection and assessment of lymph nodes is usually performed manually, which can be error-prone and timeconsuming. We therefore propose a method for the automatic detection of mediastinal, hilar, and intrapulmonary lymph node candidates in contrast-enhanced chest CT. Based on the segmentation of important mediastinal anatomy (bronchial tree, aortic arch) and making use of anatomical knowledge, we utilize Hessian eigenvalues to detect lymph node candidates. As lymph nodes can be characterized as blob-like structures of varying size and shape within a specific intensity interval, we can utilize these characteristics to reduce the number of false positive candidates significantly. We applied our method to 5 cases suspected to have lung cancer. The processing time of our algorithm did not exceed 6 minutes, and we achieved an average sensitivity of 82.1% and an average precision of 13.3%.

SU-E-QI-21: Iodinated Contrast Agent Time Course In Human Brain Metastasis: A Study For Stereotactic Synchrotron Radiotherapy Clinical Trials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Obeid, L; Esteve, F; Adam, J

2014-06-15

Purpose: Synchrotron stereotactic radiotherapy (SSRT) is an innovative treatment combining the selective accumulation of heavy elements in tumors with stereotactic irradiations using monochromatic medium energy x-rays from a synchrotron source. Phase I/II clinical trials on brain metastasis are underway using venous infusion of iodinated contrast agents. The radiation dose enhancement depends on the amount of iodine in the tumor and its time course. In the present study, the reproducibility of iodine concentrations between the CT planning scan day (Day 0) and the treatment day (Day 10) was assessed in order to predict dose errors. Methods: For each of days 0more » and 10, three patients received a biphasic intravenous injection of iodinated contrast agent (40 ml, 4 ml/s, followed by 160 ml, 0.5 ml/s) in order to ensure stable intra-tumoral amounts of iodine during the treatment. Two volumetric CT scans (before and after iodine injection) and a multi-slice dynamic CT of the brain were performed using conventional radiotherapy CT (Day 0) or quantitative synchrotron radiation CT (Day 10). A 3D rigid registration was processed between images. The absolute and relative differences of absolute iodine concentrations and their corresponding dose errors were evaluated in the GTV and PTV used for treatment planning. Results: The differences in iodine concentrations remained within the standard deviation limits. The 3D absolute differences followed a normal distribution centered at zero mg/ml with a variance (∼1 mg/ml) which is related to the image noise. Conclusion: The results suggest that dose errors depend only on the image noise. This study shows that stable amounts of iodine are achievable in brain metastasis for SSRT treatment in a 10 days interval.« less

A novel imaging technique for fusion of high-quality immobilised MR images of the head and neck with CT scans for radiotherapy target delineation.

PubMed

Webster, G J; Kilgallon, J E; Ho, K F; Rowbottom, C G; Slevin, N J; Mackay, R I

2009-06-01

Uncertainty and inconsistency are observed in target volume delineation in the head and neck for radiotherapy treatment planning based only on CT imaging. Alternative modalities such as MRI have previously been incorporated into the delineation process to provide additional anatomical information. This work aims to improve on previous studies by combining good image quality with precise patient immobilisation in order to maintain patient position between scans. MR images were acquired using quadrature coils placed over the head and neck while the patient was immobilised in the treatment position using a five-point thermoplastic shell. The MR image and CT images were automatically fused in the Pinnacle treatment planning system using Syntegra software. Image quality, distortion and accuracy of the image registration using patient anatomy were evaluated. Image quality was found to be superior to that acquired using the body coil, while distortion was < 1.0 mm to a radius of 8.7 cm from the scan centre. Image registration accuracy was found to be 2.2 mm (+/- 0.9 mm) and < 3.0 degrees (n = 6). A novel MRI technique that combines good image quality with patient immobilization has been developed and is now in clinical use. The scan duration of approximately 15 min has been well tolerated by all patients.

Impact of respiratory-correlated CT sorting algorithms on the choice of margin definition for free-breathing lung radiotherapy treatments.

PubMed

Thengumpallil, Sheeba; Germond, Jean-François; Bourhis, Jean; Bochud, François; Moeckli, Raphaël

2016-06-01

To investigate the impact of Toshiba phase- and amplitude-sorting algorithms on the margin strategies for free-breathing lung radiotherapy treatments in the presence of breathing variations. 4D CT of a sphere inside a dynamic thorax phantom was acquired. The 4D CT was reconstructed according to the phase- and amplitude-sorting algorithms. The phantom was moved by reproducing amplitude, frequency, and a mix of amplitude and frequency variations. Artefact analysis was performed for Mid-Ventilation and ITV-based strategies on the images reconstructed by phase- and amplitude-sorting algorithms. The target volume deviation was assessed by comparing the target volume acquired during irregular motion to the volume acquired during regular motion. The amplitude-sorting algorithm shows reduced artefacts for only amplitude variations while the phase-sorting algorithm for only frequency variations. For amplitude and frequency variations, both algorithms perform similarly. Most of the artefacts are blurring and incomplete structures. We found larger artefacts and volume differences for the Mid-Ventilation with respect to the ITV strategy, resulting in a higher relative difference of the surface distortion value which ranges between maximum 14.6% and minimum 4.1%. The amplitude- is superior to the phase-sorting algorithm in the reduction of motion artefacts for amplitude variations while phase-sorting for frequency variations. A proper choice of 4D CT sorting algorithm is important in order to reduce motion artefacts, especially if Mid-Ventilation strategy is used. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Automated Patient Positioning Guided by Cone-Beam CT for Prostate Radiotherapy

DTIC Science & Technology

2009-01-01

clinically implemented an automated patient positioning strategy and tested with phantom experiments; (2) developed image-to-projection deformable...31st, 2008). The goal of this project is to develop a clinically practical technique for prostate patient positioning based on newly emerged CBCT...tissue organs; Secondly, it considers both the prostate target and the organs at risk (OARs) simultaneously, thus a better clinical decision can be

Radiation Planning Assistant - A Streamlined, Fully Automated Radiotherapy Treatment Planning System

PubMed Central

Court, Laurence E.; Kisling, Kelly; McCarroll, Rachel; Zhang, Lifei; Yang, Jinzhong; Simonds, Hannah; du Toit, Monique; Trauernicht, Chris; Burger, Hester; Parkes, Jeannette; Mejia, Mike; Bojador, Maureen; Balter, Peter; Branco, Daniela; Steinmann, Angela; Baltz, Garrett; Gay, Skylar; Anderson, Brian; Cardenas, Carlos; Jhingran, Anuja; Shaitelman, Simona; Bogler, Oliver; Schmeller, Kathleen; Followill, David; Howell, Rebecca; Nelson, Christopher; Peterson, Christine; Beadle, Beth

2018-01-01

The Radiation Planning Assistant (RPA) is a system developed for the fully automated creation of radiotherapy treatment plans, including volume-modulated arc therapy (VMAT) plans for patients with head/neck cancer and 4-field box plans for patients with cervical cancer. It is a combination of specially developed in-house software that uses an application programming interface to communicate with a commercial radiotherapy treatment planning system. It also interfaces with a commercial secondary dose verification software. The necessary inputs to the system are a Treatment Plan Order, approved by the radiation oncologist, and a simulation computed tomography (CT) image, approved by the radiographer. The RPA then generates a complete radiotherapy treatment plan. For the cervical cancer treatment plans, no additional user intervention is necessary until the plan is complete. For head/neck treatment plans, after the normal tissue and some of the target structures are automatically delineated on the CT image, the radiation oncologist must review the contours, making edits if necessary. They also delineate the gross tumor volume. The RPA then completes the treatment planning process, creating a VMAT plan. Finally, the completed plan must be reviewed by qualified clinical staff. PMID:29708544

Follow-up segmentation of lung tumors in PET and CT data

NASA Astrophysics Data System (ADS)

Opfer, Roland; Kabus, Sven; Schneider, Torben; Carlsen, Ingwer C.; Renisch, Steffen; Sabczynski, Jörg

2009-02-01

Early response assessment of cancer therapy is a crucial component towards a more effective and patient individualized cancer therapy. Integrated PET/CT systems provide the opportunity to combine morphologic with functional information. We have developed algorithms which allow the user to track both tumor volume and standardized uptake value (SUV) measurements during the therapy from series of CT and PET images, respectively. To prepare for tumor volume estimation we have developed a new technique for a fast, flexible, and intuitive 3D definition of meshes. This initial surface is then automatically adapted by means of a model-based segmentation algorithm and propagated to each follow-up scan. If necessary, manual corrections can be added by the user. To determine SUV measurements a prioritized region growing algorithm is employed. For an improved workflow all algorithms are embedded in a PET/CT therapy monitoring software suite giving the clinician a unified and immediate access to all data sets. Whenever the user clicks on a tumor in a base-line scan, the courses of segmented tumor volumes and SUV measurements are automatically identified and displayed to the user as a graph plot. According to each course, the therapy progress can be classified as complete or partial response or as progressive or stable disease. We have tested our methods with series of PET/CT data from 9 lung cancer patients acquired at Princess Margaret Hospital in Toronto. Each patient underwent three PET/CT scans during a radiation therapy. Our results indicate that a combination of mean metabolic activity in the tumor with the PET-based tumor volume can lead to an earlier response detection than a purely volume based (CT diameter) or purely functional based (e.g. SUV max or SUV mean) response measures. The new software seems applicable for easy, faster, and reproducible quantification to routinely monitor tumor therapy.

SU-E-J-256: Predicting Metastasis-Free Survival of Rectal Cancer Patients Treated with Neoadjuvant Chemo-Radiotherapy by Data-Mining of CT Texture Features of Primary Lesions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhong, H; Wang, J; Shen, L

Purpose: The purpose of this study is to investigate the relationship between computed tomographic (CT) texture features of primary lesions and metastasis-free survival for rectal cancer patients; and to develop a datamining prediction model using texture features. Methods: A total of 220 rectal cancer patients treated with neoadjuvant chemo-radiotherapy (CRT) were enrolled in this study. All patients underwent CT scans before CRT. The primary lesions on the CT images were delineated by two experienced oncologists. The CT images were filtered by Laplacian of Gaussian (LoG) filters with different filter values (1.0–2.5: from fine to coarse). Both filtered and unfiltered imagesmore » were analyzed using Gray-level Co-occurrence Matrix (GLCM) texture analysis with different directions (transversal, sagittal, and coronal). Totally, 270 texture features with different species, directions and filter values were extracted. Texture features were examined with Student’s t-test for selecting predictive features. Principal Component Analysis (PCA) was performed upon the selected features to reduce the feature collinearity. Artificial neural network (ANN) and logistic regression were applied to establish metastasis prediction models. Results: Forty-six of 220 patients developed metastasis with a follow-up time of more than 2 years. Sixtyseven texture features were significantly different in t-test (p<0.05) between patients with and without metastasis, and 12 of them were extremely significant (p<0.001). The Area-under-the-curve (AUC) of ANN was 0.72, and the concordance index (CI) of logistic regression was 0.71. The predictability of ANN was slightly better than logistic regression. Conclusion: CT texture features of primary lesions are related to metastasisfree survival of rectal cancer patients. Both ANN and logistic regression based models can be developed for prediction.« less

Sequential PET/CT with [18F]-FDG Predicts Pathological Tumor Response to Preoperative Short Course Radiotherapy with Delayed Surgery in Patients with Locally Advanced Rectal Cancer Using Logistic Regression Analysis

PubMed Central

Pecori, Biagio; Lastoria, Secondo; Caracò, Corradina; Celentani, Marco; Tatangelo, Fabiana; Avallone, Antonio; Rega, Daniela; De Palma, Giampaolo; Mormile, Maria; Budillon, Alfredo; Muto, Paolo; Bianco, Francesco; Aloj, Luigi; Petrillo, Antonella; Delrio, Paolo

2017-01-01

Previous studies indicate that FDG PET/CT may predict pathological response in patients undergoing neoadjuvant chemo-radiotherapy for locally advanced rectal cancer (LARC). Aim of the current study is evaluate if pathological response can be similarly predicted in LARC patients after short course radiation therapy alone. Methods: Thirty-three patients with cT2-3, N0-2, M0 rectal adenocarcinoma treated with hypo fractionated short course neoadjuvant RT (5x5 Gy) with delayed surgery (SCRTDS) were prospectively studied. All patients underwent 3 PET/CT studies at baseline, 10 days from RT end (early), and 53 days from RT end (delayed). Maximal standardized uptake value (SUVmax), mean standardized uptake value (SUVmean) and total lesion glycolysis (TLG) of the primary tumor were measured and recorded at each PET/CT study. We use logistic regression analysis to aggregate different measures of metabolic response to predict the pathological response in the course of SCRTDS. Results: We provide straightforward formulas to classify response and estimate the probability of being a major responder (TRG1-2) or a complete responder (TRG1) for each individual. The formulas are based on the level of TLG at the early PET and on the overall proportional reduction of TLG between baseline and delayed PET studies. Conclusions: This study demonstrates that in the course of SCRTDS it is possible to estimate the probabilities of pathological tumor responses on the basis of PET/CT with FDG. Our formulas make it possible to assess the risks associated to LARC borne by a patient in the course of SCRTDS. These risk assessments can be balanced against other health risks associated with further treatments and can therefore be used to make informed therapy adjustments during SCRTDS. PMID:28060889

Sequential PET/CT with [18F]-FDG Predicts Pathological Tumor Response to Preoperative Short Course Radiotherapy with Delayed Surgery in Patients with Locally Advanced Rectal Cancer Using Logistic Regression Analysis.

PubMed

Pecori, Biagio; Lastoria, Secondo; Caracò, Corradina; Celentani, Marco; Tatangelo, Fabiana; Avallone, Antonio; Rega, Daniela; De Palma, Giampaolo; Mormile, Maria; Budillon, Alfredo; Muto, Paolo; Bianco, Francesco; Aloj, Luigi; Petrillo, Antonella; Delrio, Paolo

2017-01-01

Previous studies indicate that FDG PET/CT may predict pathological response in patients undergoing neoadjuvant chemo-radiotherapy for locally advanced rectal cancer (LARC). Aim of the current study is evaluate if pathological response can be similarly predicted in LARC patients after short course radiation therapy alone. Thirty-three patients with cT2-3, N0-2, M0 rectal adenocarcinoma treated with hypo fractionated short course neoadjuvant RT (5x5 Gy) with delayed surgery (SCRTDS) were prospectively studied. All patients underwent 3 PET/CT studies at baseline, 10 days from RT end (early), and 53 days from RT end (delayed). Maximal standardized uptake value (SUVmax), mean standardized uptake value (SUVmean) and total lesion glycolysis (TLG) of the primary tumor were measured and recorded at each PET/CT study. We use logistic regression analysis to aggregate different measures of metabolic response to predict the pathological response in the course of SCRTDS. We provide straightforward formulas to classify response and estimate the probability of being a major responder (TRG1-2) or a complete responder (TRG1) for each individual. The formulas are based on the level of TLG at the early PET and on the overall proportional reduction of TLG between baseline and delayed PET studies. This study demonstrates that in the course of SCRTDS it is possible to estimate the probabilities of pathological tumor responses on the basis of PET/CT with FDG. Our formulas make it possible to assess the risks associated to LARC borne by a patient in the course of SCRTDS. These risk assessments can be balanced against other health risks associated with further treatments and can therefore be used to make informed therapy adjustments during SCRTDS.

Relationship of Catastrophizing to Fatigue Among Women Receiving Treatment for Breast Cancer

ERIC Educational Resources Information Center

Jacobsen, Paul B.; Andrykowski, Michael A.; Thors, Christina L.

2004-01-01

This study examined the relationship of catastrophizing to fatigue in 80 women receiving chemotherapy (CT) or radiotherapy (RT) for treatment of early stage breast cancer. Findings revealed expected relationships between catastrophizing and fatigue among women receiving RT but not CT. Among RT patients, those high in catastrophizing reported…

Impact of radiotherapy and chemotherapy on biomarkers of oxidative DNA damage in lung cancer patients.

PubMed

Crohns, Marika; Saarelainen, Seppo; Erhola, Marina; Alho, Hannu; Kellokumpu-Lehtinen, Pirkko

2009-07-01

To assess oxidative damage to DNA during lung cancer (LC) treatments. Urinary levels of 8-oxoguanine (8-oxoGua) and levels of 8-oxo-2'-deoxyguanosine (8-oxodG) from urine and whole blood were determined in 36 non-cancer controls and 65 LC patients before any treatments. Samples were also obtained of LC patients during and after radiotherapy (RT, n=33) and chemotherapy (CT, n=16). Stage IV LC patients had higher urinary 8-oxoGua and 8-oxodG levels than patients with stage I-III disease (p=0.044 and p=0.034, respectively). Urinary 8-oxodG levels increased during the first week of RT (p<0.001). Nuclear 8-oxodG increased during RT and 3 months after start of RT. Nuclear 8-oxodG levels also rose between the first two CT cycles (p=0.043), and urinary 8-oxodG levels during the sixth CT cycle (p=0.009). Urinary DNA damage biomarker levels may be associated with LC stage. Both RT and CT increase the parameters of DNA oxidation.

Molecular PET imaging for biology-guided adaptive radiotherapy of head and neck cancer.

PubMed

Hoeben, Bianca A W; Bussink, Johan; Troost, Esther G C; Oyen, Wim J G; Kaanders, Johannes H A M

2013-10-01

Integration of molecular imaging PET techniques into therapy selection strategies and radiation treatment planning for head and neck squamous cell carcinoma (HNSCC) can serve several purposes. First, pre-treatment assessments can steer decisions about radiotherapy modifications or combinations with other modalities. Second, biology-based objective functions can be introduced to the radiation treatment planning process by co-registration of molecular imaging with planning computed tomography (CT) scans. Thus, customized heterogeneous dose distributions can be generated with escalated doses to tumor areas where radiotherapy resistance mechanisms are most prevalent. Third, monitoring of temporal and spatial variations in these radiotherapy resistance mechanisms early during the course of treatment can discriminate responders from non-responders. With such information available shortly after the start of treatment, modifications can be implemented or the radiation treatment plan can be adapted tailing the biological response pattern. Currently, these strategies are in various phases of clinical testing, mostly in single-center studies. Further validation in multicenter set-up is needed. Ultimately, this should result in availability for routine clinical practice requiring stable production and accessibility of tracers, reproducibility and standardization of imaging and analysis methods, as well as general availability of knowledge and expertise. Small studies employing adaptive radiotherapy based on functional dynamics and early response mechanisms demonstrate promising results. In this context, we focus this review on the widely used PET tracer (18)F-FDG and PET tracers depicting hypoxia and proliferation; two well-known radiation resistance mechanisms.

SU-G-IeP2-06: Evaluation of Registration Accuracy for Cone-Beam CT Reconstruction Techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, J; Wang, P; Zhang, H

2016-06-15

Purpose: Cone-beam (CB) computed tomography (CT) is used for image guidance during radiotherapy treatment delivery. Conventional Feldkamp and compressed sensing (CS) based CBCT recon-struction techniques are compared for image registration. This study is to evaluate the image registration accuracy of conventional and CS CBCT for head-and-neck (HN) patients. Methods: Ten HN patients with oropharyngeal tumors were retrospectively selected. Each HN patient had one planning CT (CTP) and three CBCTs were acquired during an adaptive radiotherapy proto-col. Each CBCT was reconstructed by both the conventional (CBCTCON) and compressed sens-ing (CBCTCS) methods. Two oncologists manually labeled 23 landmarks of normal tissue andmore » implanted gold markers on both the CTP and CBCTCON. Subsequently, landmarks on CTp were propagated to CBCTs, using a b-spline-based deformable image registration (DIR) and rigid registration (RR). The errors of these registration methods between two CBCT methods were calcu-lated. Results: For DIR, the mean distance between the propagated and the labeled landmarks was 2.8 mm ± 0.52 for CBCTCS, and 3.5 mm ± 0.75 for CBCTCON. For RR, the mean distance between the propagated and the labeled landmarks was 6.8 mm ± 0.92 for CBCTCS, and 8.7 mm ± 0.95 CBCTCON. Conclusion: This study has demonstrated that CS CBCT is more accurate than conventional CBCT in image registration by both rigid and non-rigid methods. It is potentially suggested that CS CBCT is an improved image modality for image guided adaptive applications.« less

An approach to contouring the dorsal vagal complex for radiotherapy planning

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Steen, Lillie; Amdur, Robert J., E-mail: amdurr@shands.ufl.edu

Multiple studies suggest that radiation dose to the area of the brainstem called the “dorsal vagal complex (DVC)” influences the frequency of nausea and vomiting during radiotherapy. The purpose of this didactic article is to describe the step-by-step process that we use to contour the general area of the DVC on axial computed tomography (CT) images as would be done for radiotherapy planning. The contouring procedure that we describe for contouring the area of the DVC is useful to medical dosimetrists and radiation oncologists.

Analysis of Electronic Densities and Integrated Doses in Multiform Glioblastomas Stereotactic Radiotherapy

NASA Astrophysics Data System (ADS)

Barón-Aznar, C.; Moreno-Jiménez, S.; Celis, M. A.; Lárraga-Gutiérrez, J. M.; Ballesteros-Zebadúa, P.

2008-08-01

Integrated dose is the total energy delivered in a radiotherapy target. This physical parameter could be a predictor for complications such as brain edema and radionecrosis after stereotactic radiotherapy treatments for brain tumors. Integrated Dose depends on the tissue density and volume. Using CT patients images from the National Institute of Neurology and Neurosurgery and BrainScansoftware, this work presents the mean density of 21 multiform glioblastomas, comparative results for normal tissue and estimated integrated dose for each case. The relationship between integrated dose and the probability of complications is discussed.

MO-F-CAMPUS-T-03: Data Driven Approaches for Determination of Treatment Table Tolerance Values for Record and Verification Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, N; DiCostanzo, D; Fullenkamp, M

2015-06-15

Purpose: To determine appropriate couch tolerance values for modern radiotherapy linac R&V systems with indexed patient setup. Methods: Treatment table tolerance values have been the most difficult to lower, due to many factors including variations in patient positioning and differences in table tops between machines. We recently installed nine linacs with similar tables and started indexing every patient in our clinic. In this study we queried our R&V database and analyzed the deviation of couch position values from the acquired values at verification simulation for all patients treated with indexed positioning. Mean and standard deviations of daily setup deviations weremore » computed in the longitudinal, lateral and vertical direction for 343 patient plans. The mean, median and standard error of the standard deviations across the whole patient population and for some disease sites were computed to determine tolerance values. Results: The plot of our couch deviation values showed a gaussian distribution, with some small deviations, corresponding to setup uncertainties on non-imaging days, and SRS/SRT/SBRT patients, as well as some large deviations which were spot checked and found to be corresponding to indexing errors that were overriden. Setting our tolerance values based on the median + 1 standard error resulted in tolerance values of 1cm lateral and longitudinal, and 0.5 cm vertical for all non- SRS/SRT/SBRT cases. Re-analizing the data, we found that about 92% of the treated fractions would be within these tolerance values (ignoring the mis-indexed patients). We also analyzed data for disease site based subpopulations and found no difference in the tolerance values that needed to be used. Conclusion: With the use of automation, auto-setup and other workflow efficiency tools being introduced into radiotherapy workflow, it is very essential to set table tolerances that allow safe treatments, but flag setup errors that need to be reassessed before treatments.« less

Evaluation of GMI and PMI diffeomorphic‐based demons algorithms for aligning PET and CT Images

PubMed Central

Yang, Juan; Zhang, You; Yin, Yong

2015-01-01

Fusion of anatomic information in computed tomography (CT) and functional information in F18‐FDG positron emission tomography (PET) is crucial for accurate differentiation of tumor from benign masses, designing radiotherapy treatment plan and staging of cancer. Although current PET and CT images can be acquired from combined F18‐FDG PET/CT scanner, the two acquisitions are scanned separately and take a long time, which may induce potential positional errors in global and local caused by respiratory motion or organ peristalsis. So registration (alignment) of whole‐body PET and CT images is a prerequisite for their meaningful fusion. The purpose of this study was to assess the performance of two multimodal registration algorithms for aligning PET and CT images. The proposed gradient of mutual information (GMI)‐based demons algorithm, which incorporated the GMI between two images as an external force to facilitate the alignment, was compared with the point‐wise mutual information (PMI) diffeomorphic‐based demons algorithm whose external force was modified by replacing the image intensity difference in diffeomorphic demons algorithm with the PMI to make it appropriate for multimodal image registration. Eight patients with esophageal cancer(s) were enrolled in this IRB‐approved study. Whole‐body PET and CT images were acquired from a combined F18‐FDG PET/CT scanner for each patient. The modified Hausdorff distance (dMH) was used to evaluate the registration accuracy of the two algorithms. Of all patients, the mean values and standard deviations (SDs) of dMH were 6.65 (± 1.90) voxels and 6.01 (± 1.90) after the GMI‐based demons and the PMI diffeomorphic‐based demons registration algorithms respectively. Preliminary results on oncological patients showed that the respiratory motion and organ peristalsis in PET/CT esophageal images could not be neglected, although a combined F18‐FDG PET/CT scanner was used for image acquisition. The PMI diffeomorphic‐based demons algorithm was more accurate than the GMI‐based demons algorithm in registering PET/CT esophageal images. PACS numbers: 87.57.nj, 87.57. Q‐, 87.57.uk PMID:26218993

Evaluation of GMI and PMI diffeomorphic-based demons algorithms for aligning PET and CT Images.

PubMed

Yang, Juan; Wang, Hongjun; Zhang, You; Yin, Yong

2015-07-08

Fusion of anatomic information in computed tomography (CT) and functional information in 18F-FDG positron emission tomography (PET) is crucial for accurate differentiation of tumor from benign masses, designing radiotherapy treatment plan and staging of cancer. Although current PET and CT images can be acquired from combined 18F-FDG PET/CT scanner, the two acquisitions are scanned separately and take a long time, which may induce potential positional errors in global and local caused by respiratory motion or organ peristalsis. So registration (alignment) of whole-body PET and CT images is a prerequisite for their meaningful fusion. The purpose of this study was to assess the performance of two multimodal registration algorithms for aligning PET and CT images. The proposed gradient of mutual information (GMI)-based demons algorithm, which incorporated the GMI between two images as an external force to facilitate the alignment, was compared with the point-wise mutual information (PMI) diffeomorphic-based demons algorithm whose external force was modified by replacing the image intensity difference in diffeomorphic demons algorithm with the PMI to make it appropriate for multimodal image registration. Eight patients with esophageal cancer(s) were enrolled in this IRB-approved study. Whole-body PET and CT images were acquired from a combined 18F-FDG PET/CT scanner for each patient. The modified Hausdorff distance (d(MH)) was used to evaluate the registration accuracy of the two algorithms. Of all patients, the mean values and standard deviations (SDs) of d(MH) were 6.65 (± 1.90) voxels and 6.01 (± 1.90) after the GMI-based demons and the PMI diffeomorphic-based demons registration algorithms respectively. Preliminary results on oncological patients showed that the respiratory motion and organ peristalsis in PET/CT esophageal images could not be neglected, although a combined 18F-FDG PET/CT scanner was used for image acquisition. The PMI diffeomorphic-based demons algorithm was more accurate than the GMI-based demons algorithm in registering PET/CT esophageal images.

Development of Prior Image-Based, High-Quality, Low-Dose Kilovoltage Cone Beam CT for Use in Adaptive Radiotherapy of Prostate Cancer

DTIC Science & Technology

2011-05-01

for the research in the next year. The aims in the next year include further develop- ment of the prior image- based , narrowly collimated CBCT imaging...further investigation planned for the next year. 5 BODY 1 Research Accomplishments 1.1 Implement narrow beam collimation for CBCT ROI imaging I have...noise level to mimic different mAs used in clinical and research modes of the CBCT system. Based upon experiences with the numerical phantom, I designed

SU-F-BRF-10: Deformable MRI to CT Validation Employing Same Day Planning MRI for Surrogate Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Padgett, K; Stoyanova, R; Johnson, P

Purpose: To compare rigid and deformable registrations of the prostate in the multi-modality setting (diagnostic-MRI to planning-CT) by utilizing a planning-MRI as a surrogate. The surrogate allows for the direct quantitative analysis which can be difficult in the multi-modality domain where intensity mapping differs. Methods: For ten subjects, T2 fast-spin-echo images were acquired at two different time points, the first several weeks prior to planning (diagnostic-MRI) and the second on the same day in which the planning CT was collected (planning-MRI). Significant effort in patient positioning and bowel/bladder preparation was undertaken to minimize distortion of the prostate in all datasets.more » The diagnostic-MRI was deformed to the planning-CT utilizing a commercially available deformable registration algorithm synthesized from local registrations. The deformed MRI was then rigidly aligned to the planning MRI which was used as the surrogate for the planning-CT. Agreement between the two MRI datasets was scored using intensity based metrics including Pearson correlation and normalized mutual information, NMI. A local analysis was performed by looking only within the prostate, proximal seminal vesicles, penile bulb and combined areas. A similar method was used to assess a rigid registration between the diagnostic-MRI and planning-CT. Results: Utilizing the NMI, the deformable registrations were superior to the rigid registrations in 9 of 10 cases demonstrating a 15.94% improvement (p-value < 0.001) within the combined area. The Pearson correlation showed similar results with the deformable registration superior in the same number of cases and demonstrating a 6.97% improvement (p-value <0.011). Conclusion: Validating deformable multi-modality registrations using spatial intensity based metrics is difficult due to the inherent differences in intensity mapping. This population provides an ideal testing ground for MRI to CT deformable registrations by obviating the need for multi-modality comparisons which are inherently more challenging. Deformable registrations generated in this work significantly outperformed rigid alignments. Research reported in this abstract was supported by the NIH National Cancer Institute R21CA153826 “MRI-Guided Radiotherapy and Biomarkers for Prostate Cancer” and Bankhead-Coley Cancer Research Program 10BT-03 “MRI-Guided Radiotherapy and Biomarkers for Prostate Cancer”.« less

MR to CT registration of brains using image synthesis

NASA Astrophysics Data System (ADS)

Roy, Snehashis; Carass, Aaron; Jog, Amod; Prince, Jerry L.; Lee, Junghoon

2014-03-01

Computed tomography (CT) is the preferred imaging modality for patient dose calculation for radiation therapy. Magnetic resonance (MR) imaging (MRI) is used along with CT to identify brain structures due to its superior soft tissue contrast. Registration of MR and CT is necessary for accurate delineation of the tumor and other structures, and is critical in radiotherapy planning. Mutual information (MI) or its variants are typically used as a similarity metric to register MRI to CT. However, unlike CT, MRI intensity does not have an accepted calibrated intensity scale. Therefore, MI-based MR-CT registration may vary from scan to scan as MI depends on the joint histogram of the images. In this paper, we propose a fully automatic framework for MR-CT registration by synthesizing a synthetic CT image from MRI using a co-registered pair of MR and CT images as an atlas. Patches of the subject MRI are matched to the atlas and the synthetic CT patches are estimated in a probabilistic framework. The synthetic CT is registered to the original CT using a deformable registration and the computed deformation is applied to the MRI. In contrast to most existing methods, we do not need any manual intervention such as picking landmarks or regions of interests. The proposed method was validated on ten brain cancer patient cases, showing 25% improvement in MI and correlation between MR and CT images after registration compared to state-of-the-art registration methods.

TU-F-12A-04: Differential Radiation Avoidance of Functional Liver Regions Defined by 99mTc-Sulfur Colloid SPECT/CT with Proton Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowen, S; Miyaoka, R; Kinahan, P

2014-06-15

Purpose: Radiotherapy for hepatocellular carcinoma patients is conventionally planned without consideration of spatial heterogeneity in hepatic function, which may increase risk of radiation-induced liver disease. Pencil beam scanning (PBS) proton radiotherapy (pRT) plans were generated to differentially decrease dose to functional liver volumes (FLV) defined on [{sup 99m}Tc]sulfur colloid (SC) SPECT/CT images (functional avoidance plans) and compared against conventional pRT plans. Methods: Three HCC patients underwent SC SPECT/CT scans for pRT planning acquired 15 min post injection over 24 min. Images were reconstructed with OSEM following scatter, collimator, and exhale CT attenuation correction. Functional liver volumes (FLV) were defined bymore » liver:spleen uptake ratio thresholds (43% to 90% maximum). Planning objectives to FLV were based on mean SC SPECT uptake ratio relative to GTV-subtracted liver and inversely scaled to mean liver dose of 20 Gy. PTV target coverage (V{sub 95}) was matched between conventional and functional avoidance plans. PBS pRT plans were optimized in RayStation for single field uniform dose (SFUD) and systematically perturbed to verify robustness to uncertainty in range, setup, and motion. Relative differences in FLV DVH and target dose heterogeneity (D{sub 2}-D{sub 98})/D50 were assessed. Results: For similar liver dose between functional avoidance and conventional PBS pRT plans (D{sub mean}≤5% difference, V{sub 18Gy}≤1% difference), dose to functional liver volumes were lower in avoidance plans but varied in magnitude across patients (FLV{sub 70%max} D{sub mean}≤26% difference, V{sub 18Gy}≤8% difference). Higher PTV dose heterogeneity in avoidance plans was associated with lower functional liver dose, particularly for the largest lesion [(D{sub 2}-D{sub 98})/D{sub 50}=13%, FLV{sub 90%max}=50% difference]. Conclusion: Differential avoidance of functional liver regions defined on sulfur colloid SPECT/CT is feasible with proton therapy. The magnitude of benefit appears to be patient specific and dependent on tumor location, size, and proximity to functional volumes. Further investigation in a larger cohort of patients may validate the clinical utility of functional avoidance planning of HCC radiotherapy.« less

Neurovascular bundle–sparing radiotherapy for prostate cancer using MRI-CT registration: A dosimetric feasibility study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cassidy, R.J., E-mail: richardjcassidy@emory.edu; Yang, X.; Liu, T.

Purpose: Sexual dysfunction after radiotherapy for prostate cancer remains an important late adverse toxicity. The neurovascular bundles (NVB) that lie posterolaterally to the prostate are typically spared during prostatectomy, but in traditional radiotherapy planning they are not contoured as an organ-at-risk with dose constraints. Our goal was to determine the dosimetric feasibility of “NVB-sparing” prostate radiotherapy while still delivering adequate dose to the prostate. Methods: Twenty-five consecutive patients with prostate cancer (with no extraprostatic disease on pelvic magnetic resonance imaging [MRI]) who that were treated with external beam radiotherapy, with the same primary planning target volume margins, to a dosemore » of 79.2 Gy were evaluated. Pelvic MRI and simulation computed tomography scans were registered using dedicated software to allow for bilateral NVB target delineation on T2-weighted MRI. A volumetric modulated arc therapy plan was generated using the NVB bilaterally with 2 mm margin as an organ to spare and compared to the patient’s previously delivered plan. Dose-volume histogram endpoints for NVB, rectum, bladder, and planning target volume 79.2 were compared between the 2 plans using a 2-tailed paired t-test. Results: The V70 for the NVB was significantly lower on the NVB-sparing plan (p <0.01), while rectum and bladder endpoints were similar. Target V100% was similar but V{sub 105%} was higher for the NVB-sparing plans (p <0.01). Conclusions: “NVB-sparing” radiotherapy is dosimetrically feasible using CT-MRI registration, and for volumetric modulated arc therapy technology — target coverage is acceptable without increased dose to other normal structures, but with higher target dose inhomogeneity. The clinical impact of “NVB-sparing” radiotherapy is currently under study at our institution.« less

New techniques for assessing response after hypofractionated radiotherapy for lung cancer

PubMed Central

Mattonen, Sarah A.; Huang, Kitty; Ward, Aaron D.; Senan, Suresh

2014-01-01

Hypofractionated radiotherapy (HFRT) is an effective and increasingly-used treatment for early stage non-small cell lung cancer (NSCLC). Stereotactic ablative radiotherapy (SABR) is a form of HFRT and delivers biologically effective doses (BEDs) in excess of 100 Gy10 in 3-8 fractions. Excellent long-term outcomes have been reported; however, response assessment following SABR is complicated as radiation induced lung injury can appear similar to a recurring tumor on CT. Current approaches to scoring treatment responses include Response Evaluation Criteria in Solid Tumors (RECIST) and positron emission tomography (PET), both of which appear to have a limited role in detecting recurrences following SABR. Novel approaches to assess response are required, but new techniques should be easily standardized across centers, cost effective, with sensitivity and specificity that improves on current CT and PET approaches. This review examines potential novel approaches, focusing on the emerging field of quantitative image feature analysis, to distinguish recurrence from fibrosis after SABR. PMID:24688782

The appearance and effects of metallic implants in CT images.

PubMed

Kairn, T; Crowe, S B; Fogg, P; Trapp, J V

2013-06-01

The computed tomography (CT) imaging artefacts that metallic medical implants produce in surrounding tissues are usually contoured and over-ridden during radiotherapy treatment planning. In cases where radiotherapy treatment beams unavoidably pass though implants, it is especially important to understand the imaging artefacts that may occur within the implants themselves. This study examines CT images of a set of simple metallic objects, immersed in water, in order to evaluate reliability and variability of CT numbers (Hounsfield units, HUs) within medical implants. Model implants with a range of sizes (heights from 2.2 to 49.6 mm), electron densities (from 2.3 to 7.7 times the electron density of water) and effective atomic numbers (from 3.9 to 9.0 times the effective atomic number of water in a CT X-ray beam) were created by stacking metal coins from several currencies. These 'implants' were CT scanned within a large (31.0 cm across) and a small (12.8 cm across) water phantom. Resulting HU values are as much as 50 % lower than the result of extrapolating standard electron density calibration data (obtained for tissue and bone densities) up to the metal densities and there is a 6 % difference between the results obtained by scanning with 120 and 140 kVp tube potentials. Profiles through the implants show localised cupping artefacts, within the implants, as well as a gradual decline in HU outside the implants that can cause the implants' sizes to be over estimated by 1.3-9.0 mm. These effects are exacerbated when the implants are scanned in the small phantom or at the side of the large phantom, due to reduced pre-hardening of the X-ray beam in these configurations. These results demonstrate the necessity of over-riding the densities of metallic implants, as well as their artefacts in tissue, in order to obtain accurate radiotherapy dose calculations.

TH-E-BRF-02: 4D-CT Ventilation Image-Based IMRT Plans Are Dosimetrically Comparable to SPECT Ventilation Image-Based Plans

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kida, S; University of Tokyo Hospital, Bunkyo, Tokyo; Bal, M

Purpose: An emerging lung ventilation imaging method based on 4D-CT can be used in radiotherapy to selectively avoid irradiating highly-functional lung regions, which may reduce pulmonary toxicity. Efforts to validate 4DCT ventilation imaging have been focused on comparison with other imaging modalities including SPECT and xenon CT. The purpose of this study was to compare 4D-CT ventilation image-based functional IMRT plans with SPECT ventilation image-based plans as reference. Methods: 4D-CT and SPECT ventilation scans were acquired for five thoracic cancer patients in an IRB-approved prospective clinical trial. The ventilation images were created by quantitative analysis of regional volume changes (amore » surrogate for ventilation) using deformable image registration of the 4D-CT images. A pair of 4D-CT ventilation and SPECT ventilation image-based IMRT plans was created for each patient. Regional ventilation information was incorporated into lung dose-volume objectives for IMRT optimization by assigning different weights on a voxel-by-voxel basis. The objectives and constraints of the other structures in the plan were kept identical. The differences in the dose-volume metrics have been evaluated and tested by a paired t-test. SPECT ventilation was used to calculate the lung functional dose-volume metrics (i.e., mean dose, V20 and effective dose) for both 4D-CT ventilation image-based and SPECT ventilation image-based plans. Results: Overall there were no statistically significant differences in any dose-volume metrics between the 4D-CT and SPECT ventilation imagebased plans. For example, the average functional mean lung dose of the 4D-CT plans was 26.1±9.15 (Gy), which was comparable to 25.2±8.60 (Gy) of the SPECT plans (p = 0.89). For other critical organs and PTV, nonsignificant differences were found as well. Conclusion: This study has demonstrated that 4D-CT ventilation image-based functional IMRT plans are dosimetrically comparable to SPECT ventilation image-based plans, providing evidence to use 4D-CT ventilation imaging for clinical applications. Supported in part by Free to Breathe Young Investigator Research Grant and NIH/NCI R01 CA 093626. The authors thank Philips Radiation Oncology Systems for the Pinnacle3 treatment planning systems.« less

Feasibility of dual-energy computed tomography in radiation therapy planning

NASA Astrophysics Data System (ADS)

Sheen, Heesoon; Shin, Han-Back; Cho, Sungkoo; Cho, Junsang; Han, Youngyih

2017-12-01

In this study, the noise level, effective atomic number ( Z eff), accuracy of the computed tomography (CT) number, and the CT number to the relative electron density EDconversion curve were estimated for virtual monochromatic energy and polychromatic energy. These values were compared to the theoretically predicted values to investigate the feasibility of the use of dual-energy CT in routine radiation therapy planning. The accuracies of the parameters were within the range of acceptability. These results can serve as a stepping stone toward the routine use of dual-energy CT in radiotherapy planning.

Imaging dose in breast radiotherapy: does breast size affect the dose to the organs at risk and the risk of secondary cancer to the contralateral breast?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Batumalai, Vikneswary, E-mail: vikneswary.batumalai@sswahs.nsw.gov.au; South Western Clinical School, University of New South Wales, Sydney, New South Wales; Quinn, Alexandra

Correct target positioning is crucial for accurate dose delivery in breast radiotherapy resulting in utilisation of daily imaging. However, the radiation dose from daily imaging is associated with increased probability of secondary induced cancer. The aim of this study was to quantify doses associated with three imaging modalities and investigate the correlation of dose and varying breast size in breast radiotherapy. Planning computed tomography (CT) data sets of 30 breast cancer patients were utilised to simulate the dose received by various organs from a megavoltage computed tomography (MV-CT), megavoltage electronic portal image (MV-EPI) and megavoltage cone-beam computed tomography (MV-CBCT). Themore » mean dose to organs adjacent to the target volume (contralateral breast, lungs, spinal cord and heart) were analysed. Pearson correlation analysis was performed to determine the relationship between imaging dose and primary breast volume and the lifetime attributable risk (LAR) of induced secondary cancer was calculated for the contralateral breast. The highest contralateral breast mean dose was from the MV-CBCT (1.79 Gy), followed by MV-EPI (0.22 Gy) and MV-CT (0.11 Gy). A similar trend was found for all organs at risk (OAR) analysed. The primary breast volume inversely correlated with the contralateral breast dose for all three imaging modalities. As the primary breast volume increases, the likelihood of a patient developing a radiation-induced secondary cancer to the contralateral breast decreases. MV-CBCT showed a stronger relationship between breast size and LAR of developing a radiation-induced contralateral breast cancer in comparison with the MV-CT and MV-EPI. For breast patients, imaging dose to OAR depends on imaging modality and treated breast size. When considering the use of imaging during breast radiotherapy, the patient's breast size and contralateral breast dose should be taken into account.« less

SU-F-T-421: Dosimetry Change During Radiotherapy and Dosimetry Difference for Rigid and Deformed Registration in the Mid-Thoracic Esophageal Carcinoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tao, C; Liu, T; Chen, J

Purpose: This study aimed to analyze dosimetry changes during radiotherapy for the mid-thoracic esophageal carcinoma, and investigate dosimetry difference between rigid and deformed registration. Methods: Twelve patients with primary middle thoracic esophageal carcinoma were selected randomly. Based on first CT scanning of each patient, plans-o were generated by experience physicists. After 20 fractions treatment, the corresponding plans-re were created with second CT scanning. And then, these two CT images were rigid and deformed registration respectively, and the dose was accumulated plan-o with plan-re. The dosimetry variation of these plans (plan-o: with 30 fractions, plan-rig: the accumulated dose with rigid registrationmore » and plan-def: the accumulated dose with deformed registration) were evaluated by paired T-test. Results: The V20 value of total lung were 32.68%, 30.3% and 29.71% for plan-o, plan-rig and plan-def respectively. The mean dose of total lung was 17.19 Gy, 16.67 Gy and 16.51 Gy for plan-o plan-rig and plan-def respectively. There were significant differences between plan-o and plan-rig or plan-def for both V20 and mean dose of total lung (with p= 0.003, p= 0.000 for V20 and p=0.008, p= 0.000 for mean dose respectively). There was no significant difference between plan-rig and plan-def (with p=0.118 for V20 and p=0.384 for mean dose). The max dose of spinal-cord was 41.95 Gy, 41.48 Gy and 41.4 Gy for plan-o, plan-rig and plan-def respectively. There were no significant differences for the max dose of spinal-cord between these plans. Conclusion: The target volume changes and anatomic position displacement of mid-thoracic esophageal carcinoma should not be neglected in clinics. These changes would cause overdose in normal tissue. Therefore, it is necessary to have another CT scanning and re-plan during the mid-thoracic esophageal carcinoma radiotherapy. And the dosimetry difference between rigid and deformed fusions was not found in this study.« less

Technical Note: FreeCT_wFBP: A robust, efficient, open-source implementation of weighted filtered backprojection for helical, fan-beam CT.

PubMed

Hoffman, John; Young, Stefano; Noo, Frédéric; McNitt-Gray, Michael

2016-03-01

With growing interest in quantitative imaging, radiomics, and CAD using CT imaging, the need to explore the impacts of acquisition and reconstruction parameters has grown. This usually requires extensive access to the scanner on which the data were acquired and its workflow is not designed for large-scale reconstruction projects. Therefore, the authors have developed a freely available, open-source software package implementing a common reconstruction method, weighted filtered backprojection (wFBP), for helical fan-beam CT applications. FreeCT_wFBP is a low-dependency, GPU-based reconstruction program utilizing c for the host code and Nvidia CUDA C for GPU code. The software is capable of reconstructing helical scans acquired with arbitrary pitch-values, and sampling techniques such as flying focal spots and a quarter-detector offset. In this work, the software has been described and evaluated for reconstruction speed, image quality, and accuracy. Speed was evaluated based on acquisitions of the ACR CT accreditation phantom under four different flying focal spot configurations. Image quality was assessed using the same phantom by evaluating CT number accuracy, uniformity, and contrast to noise ratio (CNR). Finally, reconstructed mass-attenuation coefficient accuracy was evaluated using a simulated scan of a FORBILD thorax phantom and comparing reconstructed values to the known phantom values. The average reconstruction time evaluated under all flying focal spot configurations was found to be 17.4 ± 1.0 s for a 512 row × 512 column × 32 slice volume. Reconstructions of the ACR phantom were found to meet all CT Accreditation Program criteria including CT number, CNR, and uniformity tests. Finally, reconstructed mass-attenuation coefficient values of water within the FORBILD thorax phantom agreed with original phantom values to within 0.0001 mm(2)/g (0.01%). FreeCT_wFBP is a fast, highly configurable reconstruction package for third-generation CT available under the GNU GPL. It shows good performance with both clinical and simulated data.

Atlas-based segmentation technique incorporating inter-observer delineation uncertainty for whole breast

NASA Astrophysics Data System (ADS)

Bell, L. R.; Dowling, J. A.; Pogson, E. M.; Metcalfe, P.; Holloway, L.

2017-01-01

Accurate, efficient auto-segmentation methods are essential for the clinical efficacy of adaptive radiotherapy delivered with highly conformal techniques. Current atlas based auto-segmentation techniques are adequate in this respect, however fail to account for inter-observer variation. An atlas-based segmentation method that incorporates inter-observer variation is proposed. This method is validated for a whole breast radiotherapy cohort containing 28 CT datasets with CTVs delineated by eight observers. To optimise atlas accuracy, the cohort was divided into categories by mean body mass index and laterality, with atlas’ generated for each in a leave-one-out approach. Observer CTVs were merged and thresholded to generate an auto-segmentation model representing both inter-observer and inter-patient differences. For each category, the atlas was registered to the left-out dataset to enable propagation of the auto-segmentation from atlas space. Auto-segmentation time was recorded. The segmentation was compared to the gold-standard contour using the dice similarity coefficient (DSC) and mean absolute surface distance (MASD). Comparison with the smallest and largest CTV was also made. This atlas-based auto-segmentation method incorporating inter-observer variation was shown to be efficient (<4min) and accurate for whole breast radiotherapy, with good agreement (DSC>0.7, MASD <9.3mm) between the auto-segmented contours and CTV volumes.

Combining deep learning with anatomical analysis for segmentation of the portal vein for liver SBRT planning

NASA Astrophysics Data System (ADS)

Ibragimov, Bulat; Toesca, Diego; Chang, Daniel; Koong, Albert; Xing, Lei

2017-12-01

Automated segmentation of the portal vein (PV) for liver radiotherapy planning is a challenging task due to potentially low vasculature contrast, complex PV anatomy and image artifacts originated from fiducial markers and vasculature stents. In this paper, we propose a novel framework for automated segmentation of the PV from computed tomography (CT) images. We apply convolutional neural networks (CNNs) to learn the consistent appearance patterns of the PV using a training set of CT images with reference annotations and then enhance the PV in previously unseen CT images. Markov random fields (MRFs) were further used to smooth the results of the enhancement of the CNN enhancement and remove isolated mis-segmented regions. Finally, CNN-MRF-based enhancement was augmented with PV centerline detection that relied on PV anatomical properties such as tubularity and branch composition. The framework was validated on a clinical database with 72 CT images of patients scheduled for liver stereotactic body radiation therapy. The obtained accuracy of the segmentation was DSC= 0.83 and \

MO-DE-210-03: Ultrasound imaging is an attractive method for image guided radiation treatment (IGRT), by itself or to complement other imaging modalities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding, K.

Ultrasound imaging is an attractive method for image guided radiation treatment (IGRT), by itself or to complement other imaging modalities. It is inexpensive, portable and provides good soft tissue contrast. For challenging soft tissue targets such as pancreatic cancer, ultrasound imaging can be used in combination with pre-treatment MRI and/or CT to transfer important anatomical features for target localization at time of treatment. The non-invasive and non-ionizing nature of ultrasound imaging is particularly powerful for intra-fraction localization and monitoring. Recognizing these advantages, efforts are being made to incorporate novel robotic approaches to position and manipulate the ultrasound probe during irradiation.more » These recent enabling developments hold potential to bring ultrasound imaging to a new level of IGRT applications. However, many challenges, not limited to image registration, robotic deployment, probe interference and image acquisition rate, need to be addressed to realize the full potential of IGRT with ultrasound imaging. Learning Objectives: Understand the benefits and limitations in using ultrasound to augment MRI and/or CT for motion monitoring during radiation therapy delivery. Understanding passive and active robotic approaches to implement ultrasound imaging for intra-fraction monitoring. Understand issues of probe interference with radiotherapy treatment. Understand the critical clinical workflow for effective and reproducible IGRT using ultrasound guidance. The work of X.L. is supported in part by Elekta; J.W. and K.D. is supported in part by a NIH grant R01 CA161613 and by Elekta; D.H. is support in part by a NIH grant R41 CA174089.« less

Radiation techniques used in patients with breast cancer: Results of a survey in Spain

PubMed Central

Algara, Manuel; Arenas, Meritxell; De las Peñas Eloisa Bayo, Dolores; Muñoz, Julia; Carceller, José Antonio; Salinas, Juan; Moreno, Ferran; Martínez, Francisco; González, Ezequiel; Montero, Ángel

2012-01-01

Aim To evaluate the resources and techniques used in the irradiation of patients with breast cancer after lumpectomy or mastectomy and the status of implementation of new techniques and therapeutic schedules in our country. Background The demand for cancer care has increased among the Spanish population, as long as cancer treatment innovations have proliferated. Radiation therapy in breast cancer has evolved exponentially in recent years with the implementation of three-dimensional conformal radiotherapy, intensity modulated radiotherapy, image guided radiotherapy and hypofractionation. Material and Methods An original survey questionnaire was sent to institutions participating in the SEOR-Mama group (GEORM). In total, the standards of practice in 969 patients with breast cancer after surgery were evaluated. Results The response rate was 70% (28/40 centers). In 98.5% of cases 3D conformal treatment was used. All the institutions employed CT-based planning treatment. Boost was performed in 56.4% of patients: electrons in 59.8%, photons in 23.7% and HDR brachytherapy in 8.8%. Fractionation was standard in 93.1% of patients. Supine position was the most frequent. Only 3 centers used prone position. The common organs of risk delimited were: homolateral lung (80.8%) and heart (80.8%). In 84% histograms were used. An 80.8% of the centers used isocentric technique. In 62.5% asymmetric fields were employed. CTV was delimited in 46.2%, PTV in 65% and both in 38.5%. A 65% of the centers checked with portal films. IMRT and hypofractionation were used in 1% and in 5.5% respectively. Conclusion In most of centers, 3D conformal treatment and CT-based planning treatment were used. IMRT and hypofractionation are currently poorly implemented in Spain. PMID:24377012

Individually optimized contrast-enhanced 4D-CT for radiotherapy simulation in pancreatic ductal adenocarcinoma

PubMed Central

Xue, Ming; Lane, Barton F.; Kang, Min Kyu; Patel, Kruti; Regine, William F.; Klahr, Paul; Wang, Jiahui; Chen, Shifeng; D’Souza, Warren; Lu, Wei

2016-01-01

Purpose: To develop an individually optimized contrast-enhanced (CE) 4D-computed tomography (CT) for radiotherapy simulation in pancreatic ductal adenocarcinomas (PDA). Methods: Ten PDA patients were enrolled. Each underwent three CT scans: a 4D-CT immediately following a CE 3D-CT and an individually optimized CE 4D-CT using test injection. Three physicians contoured the tumor and pancreatic tissues. Image quality scores, tumor volume, motion, tumor-to-pancreas contrast, and contrast-to-noise ratio (CNR) were compared in the three CTs. Interobserver variations were also evaluated in contouring the tumor using simultaneous truth and performance level estimation. Results: Average image quality scores for CE 3D-CT and CE 4D-CT were comparable (4.0 and 3.8, respectively; P = 0.082), and both were significantly better than that for 4D-CT (2.6, P < 0.001). Tumor-to-pancreas contrast results were comparable in CE 3D-CT and CE 4D-CT (15.5 and 16.7 Hounsfield units (HU), respectively; P = 0.21), and the latter was significantly higher than in 4D-CT (9.2 HU, P = 0.001). Image noise in CE 3D-CT (12.5 HU) was significantly lower than in CE 4D-CT (22.1 HU, P = 0.013) and 4D-CT (19.4 HU, P = 0.009). CNRs were comparable in CE 3D-CT and CE 4D-CT (1.4 and 0.8, respectively; P = 0.42), and both were significantly better in 4D-CT (0.6, P = 0.008 and 0.014). Mean tumor volumes were significantly smaller in CE 3D-CT (29.8 cm3, P = 0.03) and CE 4D-CT (22.8 cm3, P = 0.01) than in 4D-CT (42.0 cm3). Mean tumor motion was comparable in 4D-CT and CE 4D-CT (7.2 and 6.2 mm, P = 0.17). Interobserver variations were comparable in CE 3D-CT and CE 4D-CT (Jaccard index 66.0% and 61.9%, respectively) and were worse for 4D-CT (55.6%) than CE 3D-CT. Conclusions: CE 4D-CT demonstrated characteristics comparable to CE 3D-CT, with high potential for simultaneously delineating the tumor and quantifying tumor motion with a single scan. PMID:27782710

Adaptive Radiotherapy Planning on Decreasing Gross Tumor Volumes as Seen on Megavoltage Computed Tomography Images

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woodford, Curtis; Yartsev, Slav; Dar, A. Rashid

2007-11-15

Purpose: To evaluate gross tumor volume (GTV) changes for patients with non-small-cell lung cancer by using daily megavoltage (MV) computed tomography (CT) studies acquired before each treatment fraction on helical tomotherapy and to relate the potential benefit of adaptive image-guided radiotherapy to changes in GTV. Methods and Materials: Seventeen patients were prescribed 30 fractions of radiotherapy on helical tomotherapy for non-small-cell lung cancer at London Regional Cancer Program from Dec 2005 to March 2007. The GTV was contoured on the daily MVCT studies of each patient. Adapted plans were created using merged MVCT-kilovoltage CT image sets to investigate the advantagesmore » of replanning for patients with differing GTV regression characteristics. Results: Average GTV change observed over 30 fractions was -38%, ranging from -12 to -87%. No significant correlation was observed between GTV change and patient's physical or tumor features. Patterns of GTV changes in the 17 patients could be divided broadly into three groups with distinctive potential for benefit from adaptive planning. Conclusions: Changes in GTV are difficult to predict quantitatively based on patient or tumor characteristics. If changes occur, there are points in time during the treatment course when it may be appropriate to adapt the plan to improve sparing of normal tissues. If GTV decreases by greater than 30% at any point in the first 20 fractions of treatment, adaptive planning is appropriate to further improve the therapeutic ratio.« less

About a method for compressing x-ray computed microtomography data

NASA Astrophysics Data System (ADS)

Mancini, Lucia; Kourousias, George; Billè, Fulvio; De Carlo, Francesco; Fidler, Aleš

2018-04-01

The management of scientific data is of high importance especially for experimental techniques that produce big data volumes. Such a technique is x-ray computed tomography (CT) and its community has introduced advanced data formats which allow for better management of experimental data. Rather than the organization of the data and the associated meta-data, the main topic on this work is data compression and its applicability to experimental data collected from a synchrotron-based CT beamline at the Elettra-Sincrotrone Trieste facility (Italy) and studies images acquired from various types of samples. This study covers parallel beam geometry, but it could be easily extended to a cone-beam one. The reconstruction workflow used is the one currently in operation at the beamline. Contrary to standard image compression studies, this manuscript proposes a systematic framework and workflow for the critical examination of different compression techniques and does so by applying it to experimental data. Beyond the methodology framework, this study presents and examines the use of JPEG-XR in combination with HDF5 and TIFF formats providing insights and strategies on data compression and image quality issues that can be used and implemented at other synchrotron facilities and laboratory systems. In conclusion, projection data compression using JPEG-XR appears as a promising, efficient method to reduce data file size and thus to facilitate data handling and image reconstruction.

Prospective Trial of High-Dose Reirradiation Using Daily Image Guidance With Intensity-Modulated Radiotherapy for Recurrent and Second Primary Head-and-Neck Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Allen M., E-mail: allen.chen@ucdmc.ucdavis.edu; Farwell, D. Gregory; Luu, Quang

2011-07-01

Purpose: To report a single-institutional experience using intensity-modulated radiotherapy with daily image-guided radiotherapy for the reirradiation of recurrent and second cancers of the head and neck. Methods and Materials: Twenty-one consecutive patients were prospectively treated with intensity-modulated radiotherapy from February 2006 to March 2009 to a median dose of 66 Gy (range, 60-70 Gy). None of these patients received concurrent chemotherapy. Daily helical megavoltage CT scans were obtained before each fraction as part of an image-guided radiotherapy registration protocol for patient alignment. Results: The 1- and 2-year estimates of in-field control were 72% and 65%, respectively. A total of 651more » daily megavoltage CT scans were obtained. The mean systematic shift to account for interfraction motion was 1.38 {+-} 1.25 mm, 1.79 {+-} 1.45 mm, and 1.98 {+-} 1.75 mm for the medial-lateral, superior-inferior, and anterior-posterior directions, respectively. Pretreatment shifts of >3 mm occurred in 19% of setups in the medial-lateral, 27% in the superior-inferior, and 33% in the anterior-posterior directions, respectively. There were no treatment-related fatalities or hospitalizations. Complications included skin desquamation, odynophagia, otitis externa, keratitis, naso-lacrimal duct stenosis, and brachial plexopathy. Conclusions: Intensity-modulated radiotherapy with daily image guidance results in effective disease control with relatively low morbidity and should be considered for selected patients with recurrent and second primary cancers of the head and neck.« less

Medical physics practice in the next decade

PubMed Central

Paliwal, Bhudatt

2006-01-01

Impressive advances in computers and materials science have fueled a broad-based confluence of basic science breakthroughs. These advances are making us reformulate our learning, teaching and credentialing methodologies and research and development frontiers. We are now in the age of molecular medicine. In the entire field of health care, a paradigm shift from population-based solutions to individual specific care is taking place. These trends are reshaping the practice of medical physics. In this short presentation, examples are given to illustrate developments in image-guided intensity-modulated and adaptive helical tomotherapy, enhanced application of intensity modulation radiotherapy (IMRT) using adaptive radiotherapy and conformal avoidance. These advances include improved normal tissue sparing and permit dose reconstruction and verification, thereby allowing significant biologically effective dose escalation and reduced radiation toxicity. The intrinsic capability of helical TomoTherapy for megavoltage CT imaging for IMRT image-guidance is also discussed. Finally developments in motion management are described. PMID:22275799

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Z; Greskovich, J; Xia, P

Purpose: To generate virtual phantoms with clinically relevant deformation and use them to objectively evaluate geometric and dosimetric uncertainties of deformable image registration (DIR) algorithms. Methods: Ten lung cancer patients undergoing adaptive 3DCRT planning were selected. For each patient, a pair of planning CT (pCT) and replanning CT (rCT) were used as the basis for virtual phantom generation. Manually adjusted meshes were created for selected ROIs (e.g. PTV, lungs, spinal cord, esophagus, and heart) on pCT and rCT. The mesh vertices were input into a thin-plate spline algorithm to generate a reference displacement vector field (DVF). The reference DVF wasmore » used to deform pCT to generate a simulated replanning CT (srCT) that was closely matched to rCT. Three DIR algorithms (Demons, B-Spline, and intensity-based) were applied to these ten virtual phantoms. The images, ROIs, and doses were mapped from pCT to srCT using the DVFs computed by these three DIRs and compared to those mapped using the reference DVF. Results: The average Dice coefficients for selected ROIs were from 0.85 to 0.96 for Demons, from 0.86 to 0.97 for intensity-based, and from 0.76 to 0.95 for B-Spline. The average Hausdorff distances for selected ROIs were from 2.2 to 5.4 mm for Demons, from 2.3 to 6.8 mm for intensity-based, and from 2.4 to 11.4 mm for B-Spline. The average absolute dose errors for selected ROIs were from 0.2 to 0.6 Gy for Demons, from 0.1 to 0.5 Gy for intensity-based, and from 0.5 to 1.5 Gy for B-Spline. Conclusion: Virtual phantoms were modeled after patients with lung cancer and were clinically relevant for adaptive radiotherapy treatment replanning. Virtual phantoms with known DVFs serve as references and can provide a fair comparison when evaluating different DIRs. Demons and intensity-based DIRs were shown to have smaller geometric and dosimetric uncertainties than B-Spline. Z Shen: None; K Bzdusek: an employee of Philips Healthcare; J Greskovich: None; P Xia: received research grants from Philips Healthcare and Siemens Healthcare.« less

Generation of synthetic CT data using patient specific daily MR image data and image registration

NASA Astrophysics Data System (ADS)

Melanie Kraus, Kim; Jäkel, Oliver; Niebuhr, Nina I.; Pfaffenberger, Asja

2017-02-01

To fully exploit the advantages of magnetic resonance imaging (MRI) for radiotherapy (RT) treatment planning, a method is required to overcome the problem of lacking electron density information. We aim to establish and evaluate a new method for computed tomography (CT) data generation based on MRI and image registration. The thereby generated CT data is used for dose accumulation. We developed a process flow based on an initial pair of rigidly co-registered CT and T2-weighted MR image representing the same anatomical situation. Deformable image registration using anatomical landmarks is performed between the initial MRI data and daily MR images. The resulting transformation is applied to the initial CT, thus fractional CT data is generated. Furthermore, the dose for a photon intensity modulated RT (IMRT) or intensity modulated proton therapy (IMPT) plan is calculated on the generated fractional CT and accumulated on the initial CT via inverse transformation. The method is evaluated by the use of phantom CT and MRI data. Quantitative validation is performed by evaluation of the mean absolute error (MAE) between the measured and the generated CT. The effect on dose accumulation is examined by means of dose-volume parameters. One patient case is presented to demonstrate the applicability of the method introduced here. Overall, CT data derivation lead to MAEs with a median of 37.0 HU ranging from 29.9 to 66.6 HU for all investigated tissues. The accuracy of image registration showed to be limited in the case of unexpected air cavities and at tissue boundaries. The comparisons of dose distributions based on measured and generated CT data agree well with the published literature. Differences in dose volume parameters kept within 1.6% and 3.2% for photon and proton RT, respectively. The method presented here is particularly suited for application in adaptive RT in current clinical routine, since only minor additional technical equipment is required.

Comparison of standardized uptake value-based positron emission tomography and computed tomography target volumes in esophageal cancer patients undergoing radiotherapy.

PubMed

Vali, Faisal S; Nagda, Suneel; Hall, William; Sinacore, James; Gao, Mingcheng; Lee, Steven H; Hong, Robert; Shoup, Margaret; Emami, Bahman

2010-11-15

To study various standardized uptake value (SUV)-based approaches to ascertain the best strategy for delineating metabolic tumor volumes (MTV). Twenty-two consecutive previously treated esophageal cancer patients with positron emission tomography (PET) imaging and computed tomography (CT)-based radiotherapy plans were studied. At the level of the tumor epicenter, MTVs were delineated at 11 different thresholds: SUV ≥2, ≥2.5, ≥3, ≥3.5 (SUV(n)); ≥40%, ≥45%, and ≥50% of the maximum (SUV(n%)); and mean liver SUV + 1, 2, 3, and 4 standard deviations (SUV(Lnσ)). The volume ratio and conformality index were determined between MTVs, and the corresponding CT/endoscopic ultrasound-based gross tumor volume (GTV) at the epicenter. Means were analyzed by one-way analysis of variance for repeated measures and further compared using a paired t test for repeated measures. The mean conformality indices ranged from 0.33 to 0.48, being significantly (p < 0.05) closest to 1 at SUV(2.5) (0.47 ± 0.03) and SUV(L4σ) (0.48 ± 0.03). The mean volume ratios ranged from 0.39 to 2.82, being significantly closest to 1 at SUV(2.5) (1.18 ± 0.36) and SUV(L4σ) (1.09 ± 0.15). The mean value of the SUVs calculated using the SUV(L4σ) approach was 2.4. Regardless of the SUV thresholding method used (i.e., absolute or relative to liver mean), a threshold of approximately 2.5 yields the highest conformality index and best approximates the CT-based GTV at the epicenter. These findings may ultimately aid radiation oncologists in the delineation of the entire GTV in esophageal cancer patients. Copyright © 2010 Elsevier Inc. All rights reserved.

MO-B-BRB-01: Optimize Treatment Planning Process in Clinical Environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, W.

The radiotherapy treatment planning process has evolved over the years with innovations in treatment planning, treatment delivery and imaging systems. Treatment modality and simulation technologies are also rapidly improving and affecting the planning process. For example, Image-guided-radiation-therapy has been widely adopted for patient setup, leading to margin reduction and isocenter repositioning after simulation. Stereotactic Body radiation therapy (SBRT) and Radiosurgery (SRS) have gradually become the standard of care for many treatment sites, which demand a higher throughput for the treatment plans even if the number of treatments per day remains the same. Finally, simulation, planning and treatment are traditionally sequentialmore » events. However, with emerging adaptive radiotherapy, they are becoming more tightly intertwined, leading to iterative processes. Enhanced efficiency of planning is therefore becoming more critical and poses serious challenge to the treatment planning process; Lean Six Sigma approaches are being utilized increasingly to balance the competing needs for speed and quality. In this symposium we will discuss the treatment planning process and illustrate effective techniques for managing workflow. Topics will include: Planning techniques: (a) beam placement, (b) dose optimization, (c) plan evaluation (d) export to RVS. Planning workflow: (a) import images, (b) Image fusion, (c) contouring, (d) plan approval (e) plan check (f) chart check, (g) sequential and iterative process Influence of upstream and downstream operations: (a) simulation, (b) immobilization, (c) motion management, (d) QA, (e) IGRT, (f) Treatment delivery, (g) SBRT/SRS (h) adaptive planning Reduction of delay between planning steps with Lean systems due to (a) communication, (b) limited resource, (b) contour, (c) plan approval, (d) treatment. Optimizing planning processes: (a) contour validation (b) consistent planning protocol, (c) protocol/template sharing, (d) semi-automatic plan evaluation, (e) quality checklist for error prevention, (f) iterative process, (g) balance of speed and quality Learning Objectives: Gain familiarity with the workflow of modern treatment planning process. Understand the scope and challenges of managing modern treatment planning processes. Gain familiarity with Lean Six Sigma approaches and their implementation in the treatment planning workflow.« less

MO-B-BRB-00: Optimizing the Treatment Planning Process

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

The radiotherapy treatment planning process has evolved over the years with innovations in treatment planning, treatment delivery and imaging systems. Treatment modality and simulation technologies are also rapidly improving and affecting the planning process. For example, Image-guided-radiation-therapy has been widely adopted for patient setup, leading to margin reduction and isocenter repositioning after simulation. Stereotactic Body radiation therapy (SBRT) and Radiosurgery (SRS) have gradually become the standard of care for many treatment sites, which demand a higher throughput for the treatment plans even if the number of treatments per day remains the same. Finally, simulation, planning and treatment are traditionally sequentialmore » events. However, with emerging adaptive radiotherapy, they are becoming more tightly intertwined, leading to iterative processes. Enhanced efficiency of planning is therefore becoming more critical and poses serious challenge to the treatment planning process; Lean Six Sigma approaches are being utilized increasingly to balance the competing needs for speed and quality. In this symposium we will discuss the treatment planning process and illustrate effective techniques for managing workflow. Topics will include: Planning techniques: (a) beam placement, (b) dose optimization, (c) plan evaluation (d) export to RVS. Planning workflow: (a) import images, (b) Image fusion, (c) contouring, (d) plan approval (e) plan check (f) chart check, (g) sequential and iterative process Influence of upstream and downstream operations: (a) simulation, (b) immobilization, (c) motion management, (d) QA, (e) IGRT, (f) Treatment delivery, (g) SBRT/SRS (h) adaptive planning Reduction of delay between planning steps with Lean systems due to (a) communication, (b) limited resource, (b) contour, (c) plan approval, (d) treatment. Optimizing planning processes: (a) contour validation (b) consistent planning protocol, (c) protocol/template sharing, (d) semi-automatic plan evaluation, (e) quality checklist for error prevention, (f) iterative process, (g) balance of speed and quality Learning Objectives: Gain familiarity with the workflow of modern treatment planning process. Understand the scope and challenges of managing modern treatment planning processes. Gain familiarity with Lean Six Sigma approaches and their implementation in the treatment planning workflow.« less

MO-B-BRB-03: Systems Engineering Tools for Treatment Planning Process Optimization in Radiation Medicine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kapur, A.

The radiotherapy treatment planning process has evolved over the years with innovations in treatment planning, treatment delivery and imaging systems. Treatment modality and simulation technologies are also rapidly improving and affecting the planning process. For example, Image-guided-radiation-therapy has been widely adopted for patient setup, leading to margin reduction and isocenter repositioning after simulation. Stereotactic Body radiation therapy (SBRT) and Radiosurgery (SRS) have gradually become the standard of care for many treatment sites, which demand a higher throughput for the treatment plans even if the number of treatments per day remains the same. Finally, simulation, planning and treatment are traditionally sequentialmore » events. However, with emerging adaptive radiotherapy, they are becoming more tightly intertwined, leading to iterative processes. Enhanced efficiency of planning is therefore becoming more critical and poses serious challenge to the treatment planning process; Lean Six Sigma approaches are being utilized increasingly to balance the competing needs for speed and quality. In this symposium we will discuss the treatment planning process and illustrate effective techniques for managing workflow. Topics will include: Planning techniques: (a) beam placement, (b) dose optimization, (c) plan evaluation (d) export to RVS. Planning workflow: (a) import images, (b) Image fusion, (c) contouring, (d) plan approval (e) plan check (f) chart check, (g) sequential and iterative process Influence of upstream and downstream operations: (a) simulation, (b) immobilization, (c) motion management, (d) QA, (e) IGRT, (f) Treatment delivery, (g) SBRT/SRS (h) adaptive planning Reduction of delay between planning steps with Lean systems due to (a) communication, (b) limited resource, (b) contour, (c) plan approval, (d) treatment. Optimizing planning processes: (a) contour validation (b) consistent planning protocol, (c) protocol/template sharing, (d) semi-automatic plan evaluation, (e) quality checklist for error prevention, (f) iterative process, (g) balance of speed and quality Learning Objectives: Gain familiarity with the workflow of modern treatment planning process. Understand the scope and challenges of managing modern treatment planning processes. Gain familiarity with Lean Six Sigma approaches and their implementation in the treatment planning workflow.« less

MO-B-BRB-02: Maintain the Quality of Treatment Planning for Time-Constraint Cases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, J.

The radiotherapy treatment planning process has evolved over the years with innovations in treatment planning, treatment delivery and imaging systems. Treatment modality and simulation technologies are also rapidly improving and affecting the planning process. For example, Image-guided-radiation-therapy has been widely adopted for patient setup, leading to margin reduction and isocenter repositioning after simulation. Stereotactic Body radiation therapy (SBRT) and Radiosurgery (SRS) have gradually become the standard of care for many treatment sites, which demand a higher throughput for the treatment plans even if the number of treatments per day remains the same. Finally, simulation, planning and treatment are traditionally sequentialmore » events. However, with emerging adaptive radiotherapy, they are becoming more tightly intertwined, leading to iterative processes. Enhanced efficiency of planning is therefore becoming more critical and poses serious challenge to the treatment planning process; Lean Six Sigma approaches are being utilized increasingly to balance the competing needs for speed and quality. In this symposium we will discuss the treatment planning process and illustrate effective techniques for managing workflow. Topics will include: Planning techniques: (a) beam placement, (b) dose optimization, (c) plan evaluation (d) export to RVS. Planning workflow: (a) import images, (b) Image fusion, (c) contouring, (d) plan approval (e) plan check (f) chart check, (g) sequential and iterative process Influence of upstream and downstream operations: (a) simulation, (b) immobilization, (c) motion management, (d) QA, (e) IGRT, (f) Treatment delivery, (g) SBRT/SRS (h) adaptive planning Reduction of delay between planning steps with Lean systems due to (a) communication, (b) limited resource, (b) contour, (c) plan approval, (d) treatment. Optimizing planning processes: (a) contour validation (b) consistent planning protocol, (c) protocol/template sharing, (d) semi-automatic plan evaluation, (e) quality checklist for error prevention, (f) iterative process, (g) balance of speed and quality Learning Objectives: Gain familiarity with the workflow of modern treatment planning process. Understand the scope and challenges of managing modern treatment planning processes. Gain familiarity with Lean Six Sigma approaches and their implementation in the treatment planning workflow.« less

A software tool of digital tomosynthesis application for patient positioning in radiotherapy

PubMed Central

Dai, Jian‐Rong

2016-01-01

Digital Tomosynthesis (DTS) is an image modality in reconstructing tomographic images from two‐dimensional kV projections covering a narrow scan angles. Comparing with conventional cone‐beam CT (CBCT), it requires less time and radiation dose in data acquisition. It is feasible to apply this technique in patient positioning in radiotherapy. To facilitate its clinical application, a software tool was developed and the reconstruction processes were accelerated by graphic processing unit (GPU). Two reconstruction and two registration processes are required for DTS application which is different from conventional CBCT application which requires one image reconstruction process and one image registration process. The reconstruction stage consists of productions of two types of DTS. One type of DTS is reconstructed from cone‐beam (CB) projections covering a narrow scan angle and is named onboard DTS (ODTS), which represents the real patient position in treatment room. Another type of DTS is reconstructed from digitally reconstructed radiography (DRR) and is named reference DTS (RDTS), which represents the ideal patient position in treatment room. Prior to the reconstruction of RDTS, The DRRs are reconstructed from planning CT using the same acquisition setting of CB projections. The registration stage consists of two matching processes between ODTS and RDTS. The target shift in lateral and longitudinal axes are obtained from the matching between ODTS and RDTS in coronal view, while the target shift in longitudinal and vertical axes are obtained from the matching between ODTS and RDTS in sagittal view. In this software, both DRR and DTS reconstruction algorithms were implemented on GPU environments for acceleration purpose. The comprehensive evaluation of this software tool was performed including geometric accuracy, image quality, registration accuracy, and reconstruction efficiency. The average correlation coefficient between DRR/DTS generated by GPU‐based algorithm and CPU‐based algorithm is 0.99. Based on the measurements of cube phantom on DTS, the geometric errors are within 0.5 mm in three axes. For both cube phantom and pelvic phantom, the registration errors are within 0.5 mm in three axes. Compared with reconstruction performance of CPU‐based algorithms, the performances of DRR and DTS reconstructions are improved by a factor of 15 to 20. A GPU‐based software tool was developed for DTS application for patient positioning of radiotherapy. The geometric and registration accuracy met the clinical requirement in patient setup of radiotherapy. The high performance of DRR and DTS reconstruction algorithms was achieved by the GPU‐based computation environments. It is a useful software tool for researcher and clinician in evaluating DTS application in patient positioning of radiotherapy. PACS number(s): 87.57.nf PMID:27074482

On effective dose for radiotherapy based on doses to nontarget organs and tissues

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uselmann, Adam J., E-mail: ajuselmann@wisc.edu; Thomadsen, Bruce R.

2015-02-15

Purpose: The National Council for Radiation Protection and Measurement (NCRP) published estimates for the collective population dose and the mean effective dose to the population of the United States from medical imaging procedures for 1980/1982 and for 2006. The earlier report ignored the effective dose from radiotherapy and the latter gave a cursory discussion of the topic but again did not include it in the population exposure for various reasons. This paper explains the methodology used to calculate the effective dose in due to radiotherapy procedures in the latter NCRP report and revises the values based on more detailed modeling.more » Methods: This study calculated the dose to nontarget organs from radiotherapy for reference populations using CT images and published peripheral dose data. Results: Using International Commission on Radiological Protection (ICRP) 60 weighting factors, the total effective dose to nontarget organs in radiotherapy patients is estimated as 298 ± 194 mSv per patient, while the U.S. population effective dose is 0.939 ± 0.610 mSv per person, with a collective dose of 283 000 ± 184 000 person Sv per year. Using ICRP 103 weighting factors, the effective dose is 281 ± 183 mSv per patient, 0.887 ± 0.577 mSv per person in the U.S., and 268 000 ± 174 000 person Sv per year. The uncertainty in the calculations is largely governed by variations in patient size, which was accounted for by considering a range of patient sizes and taking the average treatment site to nontarget organ distance. Conclusions: The methods used to estimate the effective doses from radiotherapy used in NCRP Report No. 160 have been explained and the values updated.« less

Use of PET and Other Functional Imaging to Guide Target Delineation in Radiation Oncology.

PubMed

Verma, Vivek; Choi, J Isabelle; Sawant, Amit; Gullapalli, Rao P; Chen, Wengen; Alavi, Abass; Simone, Charles B

2018-06-01

Molecular and functional imaging is increasingly being used to guide radiotherapy (RT) management and target delineation. This review summarizes existing data in several disease sites of various functional imaging modalities, chiefly positron emission tomography/computed tomography (PET/CT), with respect to RT target definition and management. For gliomas, differentiation between postoperative changes and viable tumor is discussed, as well as focal dose escalation and reirradiation. Head and neck neoplasms may also benefit from precise PET/CT-based target delineation, especially for cancers of unknown primary; focal dose escalation is also described. In lung cancer, PET/CT can influence coverage of tumor volumes, dose escalation, and adaptive management. For cervical cancer, PET/CT as an adjunct to magnetic resonance imaging planning is discussed, as are dose escalation and delineation of avoidance targets such as the bone marrow. The emerging role of choline-based PET for prostate cancer and its impact on dose escalation is also described. Lastly, given the essential role of PET/CT for target definition in lymphoma, phase III trials of PET-directed management are reviewed, along with novel imaging modalities. Taken together, molecular and functional imaging approaches offer a major step to individualize radiotherapeutic care going forward. Copyright © 2018 Elsevier Inc. All rights reserved.

First-line nitrosourea-based chemotherapy in symptomatic non-resectable supratentorial pure low-grade astrocytomas.

PubMed

Frenay, M P; Fontaine, D; Vandenbos, F; Lebrun, C

2005-09-01

At the present time, there are no proven beneficial effects of chemotherapy (CT) for the treatment of pure low-grade astrocytomas. Brain radiotherapy (RT) still remains the standard treatment in order to reduce or delay tumor progression or symptoms, despite possible long-term neurologic complications. We report 10 patients, with histologically proven pure low-grade fibrillary astrocytomas, to which we administered a first-line nitrosourea-based CT. All patients were symptomatic with pharmaco-resistant epilepsy or neurologic symptoms, and had been rejected for neurosurgical resection. All patients with epilepsy had a clinical improvement with reduction in seizure frequency and 60% became seizure-free. CT was well tolerated; all patients developed myelosuppression with 40% of grade III/IV hematotoxicity. Seven were alive at the time of writing with a mean follow-up of 6.5 years (3.5-12) from first recorded symptoms. The three deceased patients died 7.5, 7.5, and 8.5 years from first symptoms. These results demonstrate that some patients with symptomatic non-resectable fibrillary low-grade astrocytomas can be treated with up-front CT to improve their neurologic status. This report suggests that benefits of CT on symptoms, survival, and quality of life should be prospectively compared with RT.

Effect of {sup 18}F-FDG PET/CT Imaging in Patients With Clinical Stage II and III Breast Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Groheux, David; Moretti, Jean-Luc; EAD Imagerie Moleculaire Diagnostique et Ciblage Therapeutique, IUH, University of Paris VII, Paris

2008-07-01

Purpose: To investigate the potential effect of using {sup 18}F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) in the initial assessment of patients with clinical Stage II or III breast cancer. Methods and Materials: During 14 consecutive months, 39 patients (40 tumors) who presented with Stage II or III breast cancer on the basis of a routine extension assessment were prospectively included in this study. PET/CT was performed in addition to the initial assessment. Results: In 3 cases, PET/CT showed extra-axillary lymph node involvement that had not been demonstrated with conventional techniques. Two of these patients had hypermetabolic lymph nodes in themore » subpectoral and infraclavicular regions, and the third had a hypermetabolic internal mammary node. PET/CT showed distant uptake in 4 women. Of these 4 women, 1 had pleural involvement and 3 had bone metastasis. Overall, of the 39 women, the PET/CT results modified the initial stage in 7 (18%). The modified staging altered the treatment plan for 5 patients (13%). It led to radiotherapy in 4 patients (bone metastasis, pleural lesion, subpectoral lymph nodes, and internal mammary nodes) and excision of, and radiotherapy to, the infraclavicular lymph nodes in 1 patient. Conclusions: PET/CT can provide information on extra-axillary lymph node involvement and can uncover occult distant metastases in a significant percentage of patients. Therefore, initial PET/CT could enable better treatment planning for patients with Stage II and III breast cancer.« less

[Impact of exposure dose reduction of radiation treatment planning CT using low tube voltage technique].

PubMed

Kouno, Takuya; Kuga, Noriyuki; Enzaki, Masahiro; Yamashita, Yuuki; Kitazato, Yumiko; Shimotabira, Haruhiko; Jinnouchi, Takashi; Kusuhara, Kazuo; Kawamura, Shinji

2015-04-01

The aim of this study was to reduce the exposed dose of radiotherapy treatment planning computed tomography (CT) by using low tube voltage technique. We used tube voltages of 80 kV, 100 kV, and 120 kV, respectively. First, we evaluated exposure dose with CT dose index (CTDI) for each voltage. Second, we compared image quality indexes such as modulation transfer function (MTF), noise power spectrum (NPS), and contrast to noise ratio (CNR) of phantom images with each voltage. Third, CT to electron density tables were measured in three voltages and monitor unit value was calculated along with clinical cases. Finally, CT surface exposed dose of chest skin was measured by thermoluminescent dosimeter (TLD). In image evaluation MTF and NPS were approximately equal; CNR slightly decreased, 2.0% for 100 kV. We performed check radiation dose accuracy for each tube voltage with each model phantom. As a result, the difference of MU value was not accepted. Finally, compared with 120 kV, CTDIvol and TLD value showed markedly decreased radiation dose, 60% for 80 kV and 30% for 100 kV. Using a technique with low tube voltages, especially 100 kV, is useful in radiotherapy treatment planning to obtain 20% dose reduction without compromising 120 kV image quality.

SU-E-J-24: Image-Guidance Using Cone-Beam CT for Stereotactic Body Radiotherapy (SBRT) of Lung Cancer Patients: Bony Alignment or Soft Tissue Alignment?

PubMed

Wang, L; Turaka, A; Meyer, J; Spoka, D; Jin, L; Fan, J; Ma, C

2012-06-01

To assess the reliability of soft tissue alignment by comparing pre- and post-treatment cone-beam CT (CBCT) for image guidance in stereotactic body radiotherapy (SBRT) of lung cancers. Our lung SBRT procedures require all patients undergo 4D CT scan in order to obtain patient-specific target motion information through reconstructed 4D data using the maximum-intensity projection (MIP) algorithm. The internal target volume (ITV) was outlined directly from the MIP images and a 3-5 mm margin expansion was then applied to the ITV to create the PTV. Conformal treatment planning was performed on the helical images, to which the MIP images were fused. Prior to each treatment, CBCT was used for image guidance by comparing with the simulation CT and for patient relocalization based on the bony anatomy. Any displacement of the patient bony structure would be considered as setup errors and would be corrected by couch shifts. Theoretically, as the PTV definition included target internal motion, no further shifts other than setup corrections should be made. However, it is our practice to have treating physicians further check target localization within the PTV. Whenever the shifts based on the soft-tissue alignment (that is, target alignment) exceeded a certain value (e.g. 5 mm), a post-treatment CBCT was carried out to ensure that the tissue alignment is reliable by comparing between pre- and post-treatment CBCT. Pre- and post-CBCT has been performed for 7 patients so far who had shifts beyond 5 mm despite bony alignment. For all patients, post CBCT confirmed that the visualized target position was kept in the same position as before treatment after adjusting for soft-tissue alignment. For the patient population studied, it is shown that soft-tissue alignment is necessary and reliable in the lung SBRT for individual cases. © 2012 American Association of Physicists in Medicine.

SU-F-T-245: The Investigation of Failure Mode and Effects Analysis and PDCA for the Radiotherapy Risk Reduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, J; Wang, J; P, J

2016-06-15

Purpose: To optimize the clinical processes of radiotherapy and to reduce the radiotherapy risks by implementing the powerful risk management tools of failure mode and effects analysis(FMEA) and PDCA(plan-do-check-act). Methods: A multidiciplinary QA(Quality Assurance) team from our department consisting of oncologists, physicists, dosimetrists, therapists and administrator was established and an entire workflow QA process management using FMEA and PDCA tools was implemented for the whole treatment process. After the primary process tree was created, the failure modes and Risk priority numbers(RPNs) were determined by each member, and then the RPNs were averaged after team discussion. Results: 3 of 9 failuremore » modes with RPN above 100 in the practice were identified in the first PDCA cycle, which were further analyzed to investigate the RPNs: including of patient registration error, prescription error and treating wrong patient. New process controls reduced the occurrence, or detectability scores from the top 3 failure modes. Two important corrective actions reduced the highest RPNs from 300 to 50, and the error rate of radiotherapy decreased remarkably. Conclusion: FMEA and PDCA are helpful in identifying potential problems in the radiotherapy process, which was proven to improve the safety, quality and efficiency of radiation therapy in our department. The implementation of the FMEA approach may improve the understanding of the overall process of radiotherapy while may identify potential flaws in the whole process. Further more, repeating the PDCA cycle can bring us closer to the goal: higher safety and accuracy radiotherapy.« less

Four-dimensional computed tomography based respiratory-gated radiotherapy with respiratory guidance system: analysis of respiratory signals and dosimetric comparison.

PubMed

Lee, Jung Ae; Kim, Chul Yong; Yang, Dae Sik; Yoon, Won Sup; Park, Young Je; Lee, Suk; Kim, Young Bum

2014-01-01

To investigate the effectiveness of respiratory guidance system in 4-dimensional computed tomography (4 DCT) based respiratory-gated radiation therapy (RGRT) by comparing respiratory signals and dosimetric analysis of treatment plans. The respiratory amplitude and period of the free, the audio device-guided, and the complex system-guided breathing were evaluated in eleven patients with lung or liver cancers. The dosimetric parameters were assessed by comparing free breathing CT plan and 4 DCT-based 30-70% maximal intensity projection (MIP) plan. The use of complex system-guided breathing showed significantly less variation in respiratory amplitude and period compared to the free or audio-guided breathing regarding the root mean square errors (RMSE) of full inspiration (P = 0.031), full expiration (P = 0.007), and period (P = 0.007). The dosimetric parameters including V(5 Gy), V(10 Gy), V(20 Gy), V(30 Gy), V(40 Gy), and V(50 Gy) of normal liver or lung in 4 DCT MIP plan were superior over free breathing CT plan. The reproducibility and regularity of respiratory amplitude and period were significantly improved with the complex system-guided breathing compared to the free or the audio-guided breathing. In addition, the treatment plan based on the 4D CT-based MIP images acquired with the complex system guided breathing showed better normal tissue sparing than that on the free breathing CT.

Aggressive vertebral hemangioma of the thoracic spine without typical radiological appearance.

PubMed

Dang, Lei; Liu, Chen; Yang, Shao Min; Jiang, Liang; Liu, Zhong Jun; Liu, Xiao Guang; Yuan, Hui Shu; Wei, Feng; Yu, Miao

2012-10-01

Vertebral hemangioma (VH) is virtually vascular malformation, which is usually asymptomatic. Only 3.7 % of VH may become active and symptomatic, and 1 % may invade the spinal canal and/or paravertebral space. Treatment protocols for active or aggressive VHs are still in controversy. Reported treatments include radiotherapy, vertebroplasty, direct alcohol injection, embolization, surgery and a combination of these modalities. A 41-year-old lady was presented with 18 month history of intermittent back pain. CT revealed T5 osteolytic lesion with epidural and paravertebral extension. The first CT guided biopsy yielded little information. Histopathological diagnosis of the second biopsy was VH. Vertebroplasty, posterior decompression and fixation were performed followed by postoperative radiotherapy. Her symptoms were resolved immediately after the operation. At 12 months follow-up, no recurrence was detected by CT with contrast enhancement. Surgical decompression, vertebroplasty and fixation are safe and effective for aggressive VH. More attention is needed in determining the algorithm for the diagnosis and treatment of aggressive VH.

SU-E-J-220: Evaluation of Atlas-Based Auto-Segmentation (ABAS) in Head-And-Neck Adaptive Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Q; Yan, D

2014-06-01

Purpose: Evaluate the accuracy of atlas-based auto segmentation of organs at risk (OARs) on both helical CT (HCT) and cone beam CT (CBCT) images in head and neck (HN) cancer adaptive radiotherapy (ART). Methods: Six HN patients treated in the ART process were included in this study. For each patient, three images were selected: pretreatment planning CT (PreTx-HCT), in treatment CT for replanning (InTx-HCT) and a CBCT acquired in the same day of the InTx-HCT. Three clinical procedures of auto segmentation and deformable registration performed in the ART process were evaluated: a) auto segmentation on PreTx-HCT using multi-subject atlases, b)more » intra-patient propagation of OARs from PreTx-HCT to InTx-HCT using deformable HCT-to-HCT image registration, and c) intra-patient propagation of OARs from PreTx-HCT to CBCT using deformable CBCT-to-HCT image registration. Seven OARs (brainstem, cord, L/R parotid, L/R submandibular gland and mandible) were manually contoured on PreTx-HCT and InTx-HCT for comparison. In addition, manual contours on InTx-CT were copied on the same day CBCT, and a local region rigid body registration was performed accordingly for each individual OAR. For procedures a) and b), auto contours were compared to manual contours, and for c) auto contours were compared to those rigidly transferred contours on CBCT. Dice similarity coefficients (DSC) and mean surface distances of agreement (MSDA) were calculated for evaluation. Results: For procedure a), the mean DSC/MSDA of most OARs are >80%/±2mm. For intra-patient HCT-to-HCT propagation, the Resultimproved to >85%/±1.5mm. Compared to HCT-to-HCT, the mean DSC for HCT-to-CBCT propagation drops ∼2–3% and MSDA increases ∼0.2mm. This Resultindicates that the inferior imaging quality of CBCT seems only degrade auto propagation performance slightly. Conclusion: Auto segmentation and deformable propagation can generate OAR structures on HCT and CBCT images with clinically acceptable accuracy. Therefore, they can be reliably implemented in the clinical HN ART process.« less

Analysis of Electronic Densities and Integrated Doses in Multiform Glioblastomas Stereotactic Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baron-Aznar, C.; Moreno-Jimenez, S.; Celis, M. A.

2008-08-11

Integrated dose is the total energy delivered in a radiotherapy target. This physical parameter could be a predictor for complications such as brain edema and radionecrosis after stereotactic radiotherapy treatments for brain tumors. Integrated Dose depends on the tissue density and volume. Using CT patients images from the National Institute of Neurology and Neurosurgery and BrainScan(c) software, this work presents the mean density of 21 multiform glioblastomas, comparative results for normal tissue and estimated integrated dose for each case. The relationship between integrated dose and the probability of complications is discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bazalova, Magdalena, E-mail: bazalova@stanford.edu; Nelson, Geoff; Noll, John M.

Purpose: Small animal radiation therapy has advanced significantly in recent years. Whereas in the past dose was delivered using a single beam and a lead shield for sparing of healthy tissue, conformal doses can be now delivered using more complex dedicated small animal radiotherapy systems with image guidance. The goal of this paper is to investigate dose distributions for three small animal radiation treatment modalities. Methods: This paper presents a comparison of dose distributions generated by the three approaches—a single-field irradiator with a 200 kV beam and no image guidance, a small animal image-guided conformal system based on a modified microCTmore » scanner with a 120 kV beam developed at Stanford University, and a dedicated conformal system, SARRP, using a 220 kV beam developed at Johns Hopkins University. The authors present a comparison of treatment plans for the three modalities using two cases: a mouse with a subcutaneous tumor and a mouse with a spontaneous lung tumor. A 5 Gy target dose was calculated using the EGSnrc Monte Carlo codes. Results: All treatment modalities generated similar dose distributions for the subcutaneous tumor case, with the highest mean dose to the ipsilateral lung and bones in the single-field plan (0.4 and 0.4 Gy) compared to the microCT (0.1 and 0.2 Gy) and SARRP (0.1 and 0.3 Gy) plans. The lung case demonstrated that due to the nine-beam arrangements in the conformal plans, the mean doses to the ipsilateral lung, spinal cord, and bones were significantly lower in the microCT plan (2.0, 0.4, and 1.9 Gy) and the SARRP plan (1.5, 0.5, and 1.8 Gy) than in single-field irradiator plan (4.5, 3.8, and 3.3 Gy). Similarly, the mean doses to the contralateral lung and the heart were lowest in the microCT plan (1.5 and 2.0 Gy), followed by the SARRP plan (1.7 and 2.2 Gy), and they were highest in the single-field plan (2.5 and 2.4 Gy). For both cases, dose uniformity was greatest in the single-field irradiator plan followed by the SARRP plan due to the sensitivity of the lower energy microCT beam to target heterogeneities and image noise. Conclusions: The two treatment planning examples demonstrate that modern small animal radiotherapy techniques employing image guidance, variable collimation, and multiple beam angles deliver superior dose distributions to small animal tumors as compared to conventional treatments using a single-field irradiator. For deep-seated mouse tumors, however, higher-energy conformal radiotherapy could result in higher doses to critical organs compared to lower-energy conformal radiotherapy. Treatment planning optimization for small animal radiotherapy should therefore be developed to take full advantage of the novel conformal systems.« less

SU-E-J-133: Autosegmentation of Linac CBCT: Improved Accuracy Via Penalized Likelihood Reconstruction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Y

2015-06-15

Purpose: To improve the quality of kV X-ray cone beam CT (CBCT) for use in radiotherapy delivery assessment and re-planning by using penalized likelihood (PL) iterative reconstruction and auto-segmentation accuracy of the resulting CBCTs as an image quality metric. Methods: Present filtered backprojection (FBP) CBCT reconstructions can be improved upon by PL reconstruction with image formation models and appropriate regularization constraints. We use two constraints: 1) image smoothing via an edge preserving filter, and 2) a constraint minimizing the differences between the reconstruction and a registered prior image. Reconstructions of prostate therapy CBCTs were computed with constraint 1 alone andmore » with both constraints. The prior images were planning CTs(pCT) deformable-registered to the FBP reconstructions. Anatomy segmentations were done using atlas-based auto-segmentation (Elekta ADMIRE). Results: We observed small but consistent improvements in the Dice similarity coefficients of PL reconstructions over the FBP results, and additional small improvements with the added prior image constraint. For a CBCT with anatomy very similar in appearance to the pCT, we observed these changes in the Dice metric: +2.9% (prostate), +8.6% (rectum), −1.9% (bladder). For a second CBCT with a very different rectum configuration, we observed +0.8% (prostate), +8.9% (rectum), −1.2% (bladder). For a third case with significant lateral truncation of the field of view, we observed: +0.8% (prostate), +8.9% (rectum), −1.2% (bladder). Adding the prior image constraint raised Dice measures by about 1%. Conclusion: Efficient and practical adaptive radiotherapy requires accurate deformable registration and accurate anatomy delineation. We show here small and consistent patterns of improved contour accuracy using PL iterative reconstruction compared with FBP reconstruction. However, the modest extent of these results and the pattern of differences across CBCT cases suggest that significant further development will be required to make CBCT useful to adaptive radiotherapy.« less

Radiotherapy in cT3 prostatic carcinoma: retrospective comparison between neoadjuvant and adjuvant hormonotherapy.

PubMed

Cellini, Numa; Luzi, Stefano; Morganti, Alessio Giuseppe; Valentini, Vincenzo; Mantini, Giovanna; Racioppi, Marco; Smaniotto, Daniela; Leone, Mariavittoria; Mattiucci, Gian Carlo; Digesù, Cinzia; Giustacchini, Mario; Destito, Antonio; Alcini, Eugenio

2004-01-01

The aim of this study was to retrospectively compare the clinical outcomes achieved in 2 groups of patients with cT3 prostatic carcinoma undergoing neoadjuvant hormonotherapy and neoadjuvant hormonotherapy plus adjuvant hormonotherapy with external beam radiotherapy. One hundred patients with cT3N0M0 prostatic carcinoma underwent radiotherapy to pelvic lymph nodes (45 Gy, 1.8 Gy/fraction) with a booster dose (65-70 Gy) to the prostatic cavity. Forty-four patients received neoadjuvant hormonotherapy (goserelin, starting 2 months before radiotherapy and continuing until the end of irradiation); 56 patients received neoadjuvant hormonotherapy plus adjuvant goserelin until disease progression, if present. Patients undergoing adjuvant hormonotherapy as compared to those who received exclusive neoadjuvant therapy showed a higher reduction in PSA level below 1.0 ng/ml (p = 0.0211), a lower incidence of biochemical failures (p = 0.0170), a lower incidence of hematogenous metastases (p = 0.0320) and a trend suggestive of a better disease-free survival (p = 0.0660). At univariate analysis (logrank), Gleason score did not show a significant correlation with any of the end points analyzed. To the contrary, patients with tumor <15 mm showed a better local control (p = 0.0347) and biochemical failure-free survival (p = 0.0102). Furthermore, a trend between initial PSA level and incidence of hematogenous metastases was observed (p = 0.0519). Patients with a posttreatment PSA level <1.0 ng/ml had a lower incidence of metastases (p = 0.0237) and a better survival (p = 0.0178); patients with complete clinical response showed a lower incidence of biochemical failures (p = 0.0469). Radiotherapy doses >70 Gy showed a trend with biochemical failure-free survival (p = 0.0554). At multivariate analysis, a correlation between Gleason score and incidence of metastases (p = 0.0232), and between tumor diameter and local control (p = 0.0178) and biochemical failure-free survival (p = 0.0290) was recorded. In patients with cT3N0M0 prostate carcinoma, prolonged hormonotherapy was shown to be significantly correlated with biochemical failure-free survival and distant metastasis-free survival. Furthermore, tumor size had a significant impact on biochemical failure-free survival as well as on local control. Copyright 2004 S. Karger AG, Basel

SU-E-J-119: Head-And-Neck Digital Phantoms for Geometric and Dosimetric Uncertainty Evaluation of CT-CBCT Deformable Image Registration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Z; Koyfman, S; Xia, P

2015-06-15

Purpose: To evaluate geometric and dosimetric uncertainties of CT-CBCT deformable image registration (DIR) algorithms using digital phantoms generated from real patients. Methods: We selected ten H&N cancer patients with adaptive IMRT. For each patient, a planning CT (CT1), a replanning CT (CT2), and a pretreatment CBCT (CBCT1) were used as the basis for digital phantom creation. Manually adjusted meshes were created for selected ROIs (e.g. PTVs, brainstem, spinal cord, mandible, and parotids) on CT1 and CT2. The mesh vertices were input into a thin-plate spline algorithm to generate a reference displacement vector field (DVF). The reference DVF was applied tomore » CBCT1 to create a simulated mid-treatment CBCT (CBCT2). The CT-CBCT digital phantom consisted of CT1 and CBCT2, which were linked by the reference DVF. Three DIR algorithms (Demons, B-Spline, and intensity-based) were applied to these ten digital phantoms. The images, ROIs, and volumetric doses were mapped from CT1 to CBCT2 using the DVFs computed by these three DIRs and compared to those mapped using the reference DVF. Results: The average Dice coefficients for selected ROIs were from 0.83 to 0.94 for Demons, from 0.82 to 0.95 for B-Spline, and from 0.67 to 0.89 for intensity-based DIR. The average Hausdorff distances for selected ROIs were from 2.4 to 6.2 mm for Demons, from 1.8 to 5.9 mm for B-Spline, and from 2.8 to 11.2 mm for intensity-based DIR. The average absolute dose errors for selected ROIs were from 0.7 to 2.1 Gy for Demons, from 0.7 to 2.9 Gy for B- Spline, and from 1.3 to 4.5 Gy for intensity-based DIR. Conclusion: Using clinically realistic CT-CBCT digital phantoms, Demons and B-Spline were shown to have similar geometric and dosimetric uncertainties while intensity-based DIR had the worst uncertainties. CT-CBCT DIR has the potential to provide accurate CBCT-based dose verification for H&N adaptive radiotherapy. Z Shen: None; K Bzdusek: an employee of Philips Healthcare; S Koyfman: None; P Xia: received research grants from Philips Healthcare and Siemens Healthcare.« less

Prognostic significance of tumor histology and computed tomographic staging for radiation treatment response of canine nasal tumors.

PubMed

Adams, William M; Kleiter, Miriam M; Thrall, Donald E; Klauer, Julia M; Forrest, Lisa J; La Due, Tracy A; Havighurst, Thomas C

2009-01-01

Prognostic significance of tumor histology and four computed tomography (CT) staging methods was tested retrospectively in dogs from three treatment centers that underwent intent-to-cure-radiotherapy for intranasal neoplasia. Disease-free and overall survival times were available for 94 dogs. A grouping of anaplastic, squamous cell, and undifferentiated carcinomas had a significantly shorter median disease-free survival (4.4 mo) than a grouping of all sarcomas (10.6 months). Disease-free survivals were not significantly different, when all carcinomas were compared with all sarcomas. The published original and modified WHO staging methods did not significantly relate to either survival endpoint. A modified human maxillary tumor staging system previously applied to canine nasal tumors was prognostically significant for both survival endpoints; a further modified version of that CT-based staging system resulted in improved significance for both survival endpoints. Dogs with unilateral intranasal involvement without bone destruction beyond the turbinates on CT, had longest median survival (23.4 months); CT evidence of cribriform plate involvement was associated with shortest median survival (6.7 months). Combining CT and histology statistically improved prognostic significance for both survival endpoints over the proposed CT staging method alone. Significance was lost when CT stages were collapsed to < four categories or histopathology groupings were collapsed to < three categories.

Prognostic factors in prostate cancer patients treated by radical external beam radiotherapy.

PubMed

Garibaldi, Elisabetta; Gabriele, Domenico; Maggio, Angelo; Delmastro, Elena; Garibaldi, Monica; Russo, Filippo; Bresciani, Sara; Stasi, Michele; Gabriele, Pietro

2017-09-01

The aim of this paper was to analyze, retrospectively, in prostate cancer patients treated in our Centre with external beam radiotherapy, the prognostic factors and their impact on the outcome in terms of cancer-specific survival (CSS), biochemical disease-free survival (BDFS) and clinical disease-free survival (CDFS). From October 1999 and March 2012, 1080 patients were treated with radiotherapy at our Institution: 87% of them were classified as ≤cT2, 83% had a Gleason Score (GS) ≤7, their mean of iPSA was 18 ng/mL, and the rate of clinical positive nodes was 1%. The mean follow-up was 81 months. The statistically significant prognostic factors for all groups of patients at both, univariate and multivariate analysis, were the GS and the iPSA. In intermediate- and high- or very-high-risk patients at multivariate analysis other prognostic factors for CSS were positive nodes on computed tomography (CT) scan and rectal preparation during the treatment; for BDFS, the prognostic factors were patient risk classification, positive lymph nodes on CT scan and rectal/bladder preparation; for CDFS, the prognostic factors were the number of positive core on biopsy (P=0.003), positive lymph nodes on CT scan, and radiotherapy (RT) dose. In high/very-high risk patient group at multivariate analysis other prognostic factors for CSS were clinical/radiological stage and RT dose, for BDFS they were adjuvant hormone therapy, clinical/radiological stage, and RT dose >77.7 Gy, and for CDFS they were clinical/radiological stage and RT dose >77.7 Gy. The results of this study confirm the prognostic factors described in the recent literature, with the addition of rectal/bladder preparation, generally known for its effect on toxicity but not yet on outcome.

Fracture risk assessment: improved evaluation of vertebral integrity among metastatic cancer patients to aid in surgical decision-making

NASA Astrophysics Data System (ADS)

Augustine, Kurt E.; Camp, Jon J.; Holmes, David R.; Huddleston, Paul M.; Lu, Lichun; Yaszemski, Michael J.; Robb, Richard A.

2012-03-01

Failure of the spine's structural integrity from metastatic disease can lead to both pain and neurologic deficit. Fractures that require treatment occur in over 30% of bony metastases. Our objective is to use computed tomography (CT) in conjunction with analytic techniques that have been previously developed to predict fracture risk in cancer patients with metastatic disease to the spine. Current clinical practice for cancer patients with spine metastasis often requires an empirical decision regarding spinal reconstructive surgery. Early image-based software systems used for CT analysis are time consuming and poorly suited for clinical application. The Biomedical Image Resource (BIR) at Mayo Clinic, Rochester has developed an image analysis computer program that calculates from CT scans, the residual load-bearing capacity in a vertebra with metastatic cancer. The Spine Cancer Assessment (SCA) program is built on a platform designed for clinical practice, with a workflow format that allows for rapid selection of patient CT exams, followed by guided image analysis tasks, resulting in a fracture risk report. The analysis features allow the surgeon to quickly isolate a single vertebra and obtain an immediate pre-surgical multiple parallel section composite beam fracture risk analysis based on algorithms developed at Mayo Clinic. The analysis software is undergoing clinical validation studies. We expect this approach will facilitate patient management and utilization of reliable guidelines for selecting among various treatment option based on fracture risk.

Utilization of cone-beam CT for offline evaluation of target volume coverage during prostate image-guided radiotherapy based on bony anatomy alignment.

PubMed

Paluska, Petr; Hanus, Josef; Sefrova, Jana; Rouskova, Lucie; Grepl, Jakub; Jansa, Jan; Kasaova, Linda; Hodek, Miroslav; Zouhar, Milan; Vosmik, Milan; Petera, Jiri

2012-01-01

To assess target volume coverage during prostate image-guided radiotherapy based on bony anatomy alignment and to assess possibility of safety margin reduction. Implementation of IGRT should influence safety margins. Utilization of cone-beam CT provides current 3D anatomic information directly in irradiation position. Such information enables reconstruction of the actual dose distribution. Seventeen prostate patients were treated with daily bony anatomy image-guidance. Cone-beam CT (CBCT) scans were acquired once a week immediately after bony anatomy alignment. After the prostate, seminal vesicles, rectum and bladder were contoured, the delivered dose distribution was reconstructed. Target dose coverage was evaluated by the proportion of the CTV encompassed by the 95% isodose. Original plans employed a 1 cm safety margin. Alternative plans assuming a smaller 7 mm margin between CTV and PTV were evaluated in the same way. Rectal and bladder volumes were compared with the initial ones. Rectal and bladder volumes irradiated with doses higher than 75 Gy, 70 Gy, 60 Gy, 50 Gy and 40 Gy were analyzed. In 12% of reconstructed plans the prostate coverage was not sufficient. The prostate underdosage was observed in 5 patients. Coverage of seminal vesicles was not satisfactory in 3% of plans. Most of the target underdosage corresponded to excessive rectal or bladder filling. Evaluation of alternative plans assuming a smaller 7 mm margin revealed 22% and 11% of plans where prostate and seminal vesicles coverage, respectively, was compromised. These were distributed over 8 and 7 patients, respectively. Sufficient dose coverage of target volumes was not achieved for all patients. Reducing of safety margin is not acceptable. Initial rectal and bladder volumes cannot be considered representative for subsequent treatment.

Optimizing radiologist e-prescribing of CT oral contrast agent using a protocoling portal.

PubMed

Wasser, Elliot J; Galante, Nicholas J; Andriole, Katherine P; Farkas, Cameron; Khorasani, Ramin

2013-12-01

The purpose of this study is to quantify the time expenditure associated with radiologist ordering of CT oral contrast media when using an integrated protocoling portal and to determine radiologists' perceptions of the ordering process. This prospective study was performed at a large academic tertiary care facility. Detailed timing information for CT inpatient oral contrast orders placed via the computerized physician order entry (CPOE) system was gathered over a 14-day period. Analyses evaluated the amount of physician time required for each component of the ordering process. Radiologists' perceptions of the ordering process were assessed by survey. Descriptive statistics and chi-square analysis were performed. A total of 96 oral contrast agent orders were placed by 13 radiologists during the study period. The average time necessary to create a protocol for each case was 40.4 seconds (average range by subject, 20.0-130.0 seconds; SD, 37.1 seconds), and the average total time to create and sign each contrast agent order was 27.2 seconds (range, 10.0-50.0 seconds; SD, 22.4 seconds). Overall, 52.5% (21/40) of survey respondents indicated that radiologist entry of oral contrast agent orders improved patient safety. A minority of respondents (15% [6/40]) indicated that contrast agent order entry was either very or extremely disruptive to workflow. Radiologist e-prescribing of CT oral contrast agents using CPOE can be embedded in a protocol workflow. Integration of health IT tools can help to optimize user acceptance and adoption.

Systematic Review of Synthetic Computed Tomography Generation Methodologies for Use in Magnetic Resonance Imaging-Only Radiation Therapy.

PubMed

Johnstone, Emily; Wyatt, Jonathan J; Henry, Ann M; Short, Susan C; Sebag-Montefiore, David; Murray, Louise; Kelly, Charles G; McCallum, Hazel M; Speight, Richard

2018-01-01

Magnetic resonance imaging (MRI) offers superior soft-tissue contrast as compared with computed tomography (CT), which is conventionally used for radiation therapy treatment planning (RTP) and patient positioning verification, resulting in improved target definition. The 2 modalities are co-registered for RTP; however, this introduces a systematic error. Implementing an MRI-only radiation therapy workflow would be advantageous because this error would be eliminated, the patient pathway simplified, and patient dose reduced. Unlike CT, in MRI there is no direct relationship between signal intensity and electron density; however, various methodologies for MRI-only RTP have been reported. A systematic review of these methods was undertaken. The PRISMA guidelines were followed. Embase and Medline databases were searched (1996 to March, 2017) for studies that generated synthetic CT scans (sCT)s for MRI-only radiation therapy. Sixty-one articles met the inclusion criteria. This review showed that MRI-only RTP techniques could be grouped into 3 categories: (1) bulk density override; (2) atlas-based; and (3) voxel-based techniques, which all produce an sCT scan from MR images. Bulk density override techniques either used a single homogeneous or multiple tissue override. The former produced large dosimetric errors (>2%) in some cases and the latter frequently required manual bone contouring. Atlas-based techniques used both single and multiple atlases and included methods incorporating pattern recognition techniques. Clinically acceptable sCTs were reported, but atypical anatomy led to erroneous results in some cases. Voxel-based techniques included methods using routine and specialized MRI sequences, namely ultra-short echo time imaging. High-quality sCTs were produced; however, use of multiple sequences led to long scanning times increasing the chances of patient movement. Using nonroutine sequences would currently be problematic in most radiation therapy centers. Atlas-based and voxel-based techniques were found to be the most clinically useful methods, with some studies reporting dosimetric differences of <1% between planning on the sCT and CT and <1-mm deviations when using sCTs for positional verification. Copyright © 2017 Elsevier Inc. All rights reserved.

Present Status of Radiotherapy in Clinical Practice

NASA Astrophysics Data System (ADS)

Duehmke, Eckhart

Aims of radiation oncology are cure from malignant diseases and - at the same time preservation of anatomy (e.g. female breast, uterus, prostate) and organ functions (e.g. brain, eye, voice, sphincter ani). At present, methods and results of clinical radiotherapy (RT) are based on experiences with natural history and radiobiology of malignant tumors in properly defined situations as well as on technical developments since World War II in geometrical and biological treatment planning in teletherapy and brachytherapy. Radiobiological research revealed tolerance limits of healthy tissues to be respected, effective total treatment doses of high cure probability depending on histology and tumor volume, and - more recently - altered fractionation schemes to be adapted to specific growth fractions and intrinsic radiosensitivities of clonogenic tumor cells. In addition, Biological Response Modifiers (BRM), such as cis-platinum, oxygen and hyperthermia may steepen cell survival curves of hypoxic tumor cells, others - such as tetrachiordekaoxid (TCDO) - may enhance repair of normal tissues. Computer assisted techniques in geometrical RT-planning based on individual healthy and pathologic anatomy (CT, MRT) provide high precision RT for well defined brain lesions by using dedicated linear accelerators (Stereotaxy). CT-based individual tissue compensators help with homogenization of distorted dose distributions in magna field irradiation for malignant lymphomas and with total body irradiation (TBI) before allogeneic bone marrow transplantation, e.g. for leukemia. RT with fast neutrons, Boron Neutron Capture Therapy (BNCT), RT with protons and heavy ions need to be tested in randomized trials before implementation into clinical routine.

Setup in a clinical workflow and impact on radiotherapy routine of an in vivo dosimetry procedure with an electronic portal imaging device

PubMed Central

Piermattei, Angelo; Kang, Shengwei; Xiao, Mingyong; Tang, Bin; Liao, Xiongfei; Xin, Xin; Grusio, Mattia

2018-01-01

High conformal techniques such as intensity-modulated radiation therapy and volumetric-modulated arc therapy are widely used in overloaded radiotherapy departments. In vivo dosimetric screening is essential in this environment to avoid important dosimetric errors. This work examines the feasibility of introducing in vivo dosimetry (IVD) checks in a radiotherapy routine. The causes of dosimetric disagreements between delivered and planned treatments were identified and corrected during the course of treatment. The efficiency of the corrections performed and the added workload needed for the entire procedure were evaluated. The IVD procedure was based on an electronic portal imaging device. A total of 3682 IVD tests were performed for 147 patients who underwent head and neck, abdomen, pelvis, breast, and thorax radiotherapy treatments. Two types of indices were evaluated and used to determine if the IVD tests were within tolerance levels: the ratio R between the reconstructed and planned isocentre doses and a transit dosimetry based on the γ-analysis of the electronic portal images. The causes of test outside tolerance level were investigated and corrected and IVD test was repeated during subsequent fraction. The time needed for each step of the IVD procedure was registered. Pelvis, abdomen, and head and neck treatments had 10% of tests out of tolerance whereas breast and thorax treatments accounted for up to 25%. The patient setup was the main cause of 90% of the IVD tests out of tolerance and the remaining 10% was due to patient morphological changes. An average time of 42 min per day was sufficient to monitor a daily workload of 60 patients in treatment. This work shows that IVD performed with an electronic portal imaging device is feasible in an overloaded department and enables the timely realignment of the treatment quality indices in order to achieve a patient’s final treatment compliant with the one prescribed. PMID:29432473

A novel surrogate to identify anatomical changes during radiotherapy of head and neck cancer patients.

PubMed

Gros, Sébastien A A; Xu, William; Roeske, John C; Choi, Mehe; Emami, Bahman; Surucu, Murat

2017-03-01

To develop a novel method to monitor external anatomical changes in head and neck cancer patients in order to triage possible adaptive radiotherapy needs. The presented approach aims to provide information on internal anatomical changes based on variations observed in external anatomy. Setup Cone Beam Computed Tomography (CBCT) images are processed to produce an accurate external contour of the patient's skin. After registering the CBCTs to the reference planning CT, the external contours from each CBCT are transferred to the initial - first week - CBCT. Contour radii, defined as the distances between an external contour and the isocenter projection in each CBCT slice, are calculated for each scan over the full 360 degrees. The changes in external anatomy are then quantified by the difference in radial distance between the external contours of any secondary CBCT relative to the initial CBCT. Finally, the radial difference is displayed in cylindrical coordinates as a 2D intensity map to highlight regions of interests with significant changes. Weekly CBCT scans from 15 head and neck patients were retrospectively analyzed to demonstrate the utility of this approach as a proof of principle. External changes suggested by the 2D radial difference map of an example patient after 23 fractions were then correlated with the changes in the gross tumor volumes and organs at risks. The resulting dosimetric effects were evaluated. An interactive standalone software application has been developed to facilitate the generation and the interpretation of the 2D intensity map. The 2D radial difference maps provided qualitative and quantitative information, such as the location and the magnitude of external contour changes and the rate at which these deviations occur. Out of the 15 patients, 10 presented clear evidence of general external volume shrinkage due to weight loss, and nine patients had at least one site of local shrinkage. Only two patients showed no signs of anatomical change during their entire treatment course. For the example patient, the mean (±σ) radial difference was 6.7 (±3.0) mm for the left parotid and 7.3 (±2.5) mm for the right parotid. The mean dose to the left and right parotids increased from 20.1 Gy to 30 Gy and from 16.3 Gy to 29.6 Gy, respectively. This novel method provides an efficient tool to visualize 3D external anatomical changes on a single 2D map. It quickly pinpoints the location of differences in anatomy during the course of radiotherapy, which can help physicians determine if a treatment plan needs to be adapted. The interactive graphic user interface developed in this study will be evaluated in an adaptive radiotherapy workflow for head and neck patients in a future prospective trial. © 2016 American Association of Physicists in Medicine.

The Survival Benefit of a Novel Trauma Workflow that Includes Immediate Whole-body Computed Tomography, Surgery, and Interventional Radiology, All in One Trauma Resuscitation Room: A Retrospective Historical Control Study.

PubMed

Kinoshita, Takahiro; Yamakawa, Kazuma; Matsuda, Hiroki; Yoshikawa, Yoshiaki; Wada, Daiki; Hamasaki, Toshimitsu; Ono, Kota; Nakamori, Yasushi; Fujimi, Satoshi

2017-09-26

The aim of this study was to evaluate the impact of a novel trauma workflow, using an interventional radiology (IVR)-computed tomography (CT) system in severe trauma. In August 2011, we installed an IVR-CT system in our trauma resuscitation room. We named it the Hybrid emergency room (ER), as it enabled us to perform all examinations and treatments required for trauma in a single place. This retrospective historical control study conducted in Japan included consecutive severe (injury severity score ≥16) blunt trauma patients. Patients were divided into 2 groups: Conventional (from August 2007 to July 2011) or Hybrid ER (from August 2011 to July 2015). We set the primary endpoint as 28-day mortality. The secondary endpoints included cause of death and time course from arrival to start of CT and surgery. Multivariable logistic regression analysis adjusted for clinically important variables was performed to evaluate the clinical outcomes. We included 696 patients: 360 in the Conventional group and 336 in the Hybrid ER group. The Hybrid ER group was significantly associated with decreased mortality [adjusted odds ratio (OR), 0.50 (95% confidence interval, 95% CI, 0.29-0.85); P = 0.011] and reduced deaths from exsanguination [0.17 (0.06-0.47); P = 0.001]. The time to CT initiation [Conventional 26 (21 to 32) minutes vs Hybrid ER 11 (8 to 16) minutes; P < 0.0001] and emergency procedure [68 (51 to 85) minutes vs 47 (37 to 57) minutes; P < 0.0001] were both shorter in the Hybrid ER group. This novel trauma workflow, comprising immediate CT diagnosis and rapid bleeding control without patient transfer, as realized in the Hybrid ER, may improve mortality in severe trauma.This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0.

Comparative evaluation of two-dimensional radiography and three dimensional computed tomography based dose-volume parameters for high-dose-rate intracavitary brachytherapy of cervical cancer: a prospective study.

PubMed

Madan, Renu; Pathy, Sushmita; Subramani, Vellaiyan; Sharma, Seema; Mohanti, Bidhu Kalyan; Chander, Subhash; Thulkar, Sanjay; Kumar, Lalit; Dadhwal, Vatsla

2014-01-01

Dosimetric comparison of two dimensional (2D) radiography and three-dimensional computed tomography (3D-CT) based dose distributions with high-dose-rate (HDR) intracavitry radiotherapy (ICRT) for carcinoma cervix, in terms of target coverage and doses to bladder and rectum. Sixty four sessions of HDR ICRT were performed in 22 patients. External beam radiotherapy to pelvis at a dose of 50 Gray in 27 fractions followed by HDR ICRT, 21 Grays to point A in 3 sessions, one week apart was planned . All patients underwent 2D-orthogonal and 3D-CT simulation for each session. Treatment plans were generated using 2D-orthogonal images and dose prescription was made at point A. 3D plans were generated using 3D-CT images after delineating target volume and organs at risk. Comparative evaluation of 2D and 3D treatment planning was made for each session in terms of target coverage (dose received by 90%, 95% and 100% of the target volume: D90, D95 and D100 respectively) and doses to bladder and rectum: ICRU-38 bladder and rectum point dose in 2D planning and dose to 0.1cc, 1cc, 2cc, 5cc, and 10cc of bladder and rectum in 3D planning. Mean doses received by 100% and 90% of the target volume were 4.24 ± 0.63 and 4.9 ± 0.56 Gy respectively. Doses received by 0.1cc, 1cc and 2cc volume of bladder were 2.88 ± 0.72, 2.5 ± 0.65 and 2.2 ± 0.57 times more than the ICRU bladder reference point. Similarly, doses received by 0.1cc, 1cc and 2cc of rectum were 1.80 ± 0.5, 1.48 ± 0.41 and 1.35 ± 0.37 times higher than ICRU rectal reference point. Dosimetric comparative evaluation of 2D and 3D CT based treatment planning for the same brachytherapy session demonstrates underestimation of OAR doses and overestimation of target coverage in 2D treatment planning.

Radiotherapy is essential after complete response to asparaginase-containing chemotherapy in early-stage extranodal nasal-type NK/T-cell lymphoma: A multicenter study from the China Lymphoma Collaborative Group (CLCG).

PubMed

Deng, Xiu-Wen; Wu, Jun-Xin; Wu, Tao; Zhu, Su-Yu; Shi, Mei; Su, Hang; Wang, Ying; He, Xia; Xu, Li-Ming; Yuan, Zhi-Yong; Zhang, Li-Ling; Wu, Gang; Qu, Bao-Lin; Qian, Li-Ting; Hou, Xiao-Rong; Zhang, Fu-Quan; Zhang, Yu-Jing; Zhu, Yuan; Cao, Jian-Zhong; Lan, Sheng-Min; Dong, Mei; Qi, Shu-Nan; Yang, Yong; Li, Ye-Xiong

2018-05-05

This study aimed to clarify the benefit of radiotherapy (RT) in patients with early-stage extranodal NK/T-cell lymphoma (NKTCL) who achieve a complete response (CR) after asparaginase-containing chemotherapy (CT). Of 240 patients achieved a CR after asparaginase-containing CT, 202 patients received additional RT (CT + RT), and 38 patients did not (CT alone). Compared to CT alone, CT + RT significantly improved overall survival (OS), disease-free survival (DFS) and locoregional control (LRC). The 5-year OS, DFS and LRC rates were 84.9%, 76.2% and 84.9% for CT + RT, compared to 58.9% (P = 0.006), 43.6% (P = 0.001) and 62.1% (P = 0.026) for CT alone. The 5-year cumulative disease recurrence rate was 18.8% for CT + RT compared to 46.9% (P = 0.003) for CT alone. High-dose RT (≥50 Gy) significantly decreased the risk of locoregional recurrence. The 5-year cumulative locoregional failure rate was 35.5% for patients receiving <50 Gy compared to 8.8% for patients receiving ≥50 Gy (P = 0.028). For patients with early-stage NKTCL who achieve a CR after asparaginase-containing CT, omission of RT results in frequent locoregional recurrence and a poor prognosis; RT is essential to improve locoregional control and survival. Copyright © 2018 Elsevier B.V. All rights reserved.

Magnetic resonance imaging for planning intracavitary brachytherapy for the treatment of locally advanced cervical cancer.

PubMed

Oñate Miranda, M; Pinho, D F; Wardak, Z; Albuquerque, K; Pedrosa, I

2016-01-01

Cervical cancer is the third most common gynecological cancer. Its treatment depends on tumor staging at the time of diagnosis, and a combination of chemotherapy and radiotherapy is the treatment of choice in locally advanced cervical cancers. The combined use of external beam radiotherapy and brachytherapy increases survival in these patients. Brachytherapy enables a larger dose of radiation to be delivered to the tumor with less toxicity for neighboring tissues with less toxicity for neighboring tissues compared to the use of external beam radiotherapy alone. For years, brachytherapy was planned exclusively using computed tomography (CT). The recent incorporation of magnetic resonance imaging (MRI) provides essential information about the tumor and neighboring structures making possible to better define the target volumes. Nevertheless, MRI has limitations, some of which can be compensated for by fusing CT and MRI. Fusing the images from the two techniques ensures optimal planning by combining the advantages of each technique. Copyright © 2015 SERAM. Published by Elsevier España, S.L.U. All rights reserved.

Geometric validation of self-gating k-space-sorted 4D-MRI vs 4D-CT using a respiratory motion phantom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yue, Yong, E-mail: yong.yue@cshs.org; Yang, Wensha; McKenzie, Elizabeth

Purpose: MRI is increasingly being used for radiotherapy planning, simulation, and in-treatment-room motion monitoring. To provide more detailed temporal and spatial MR data for these tasks, we have recently developed a novel self-gated (SG) MRI technique with advantage of k-space phase sorting, high isotropic spatial resolution, and high temporal resolution. The current work describes the validation of this 4D-MRI technique using a MRI- and CT-compatible respiratory motion phantom and comparison to 4D-CT. Methods: The 4D-MRI sequence is based on a spoiled gradient echo-based 3D projection reconstruction sequence with self-gating for 4D-MRI at 3 T. Respiratory phase is resolved by usingmore » SG k-space lines as the motion surrogate. 4D-MRI images are reconstructed into ten temporal bins with spatial resolution 1.56 × 1.56 × 1.56 mm{sup 3}. A MRI-CT compatible phantom was designed to validate the performance of the 4D-MRI sequence and 4D-CT imaging. A spherical target (diameter 23 mm, volume 6.37 ml) filled with high-concentration gadolinium (Gd) gel is embedded into a plastic box (35 × 40 × 63 mm{sup 3}) and stabilized with low-concentration Gd gel. The phantom, driven by an air pump, is able to produce human-type breathing patterns between 4 and 30 respiratory cycles/min. 4D-CT of the phantom has been acquired in cine mode, and reconstructed into ten phases with slice thickness 1.25 mm. The 4D images sets were imported into a treatment planning software for target contouring. The geometrical accuracy of the 4D MRI and CT images has been quantified using target volume, flattening, and eccentricity. The target motion was measured by tracking the centroids of the spheres in each individual phase. Motion ground-truth was obtained from input signals and real-time video recordings. Results: The dynamic phantom has been operated in four respiratory rate (RR) settings, 6, 10, 15, and 20/min, and was scanned with 4D-MRI and 4D-CT. 4D-CT images have target-stretching, partial-missing, and other motion artifacts in various phases, whereas the 4D-MRI images are visually free of those artifacts. Volume percentage difference for the 6.37 ml target ranged from 5.3% ± 4.3% to 10.3% ± 5.9% for 4D-CT, and 1.47 ± 0.52 to 2.12 ± 1.60 for 4D-MRI. With an increase of respiratory rate, the target volumetric and geometric deviations increase for 4D-CT images while remaining stable for the 4D-MRI images. Target motion amplitude errors at different RRs were measured with a range of 0.66–1.25 mm for 4D-CT and 0.2–0.42 mm for 4D-MRI. The results of Mann–Whitney tests indicated that 4D-MRI significantly outperforms 4D-CT in phase-based target volumetric (p = 0.027) and geometric (p < 0.001) measures. Both modalities achieve equivalent accuracy in measuring motion amplitude (p = 0.828). Conclusions: The k-space self-gated 4D-MRI technique provides a robust method for accurately imaging phase-based target motion and geometry. Compared to 4D-CT, the current 4D-MRI technique demonstrates superior spatiotemporal resolution, and robust resistance to motion artifacts caused by fast target motion and irregular breathing patterns. The technique can be used extensively in abdominal targeting, motion gating, and toward implementing MRI-based adaptive radiotherapy.« less