Surface dose measurement with Gafchromic EBT3 film for intensity modulated radiotherapy technique

NASA Astrophysics Data System (ADS)

Akbas, Ugur; Kesen, Nazmiye Donmez; Koksal, Canan; Okutan, Murat; Demir, Bayram; Becerir, Hatice Bilge

2017-09-01

Accurate dose measurement in the buildup region is extremely difficult. Studies have reported that treatment planning systems (TPS) cannot calculate surface dose accurately. The aim of the study was to compare the film measurements and TPS calculations for surface dose in head and neck cancer treatment using intensity modulated radiation therapy (IMRT). IMRT plans were generated for 5 head and neck cancer patients by using Varian Eclipse TPS. Quality assurance (QA) plans of these IMRT plans were created on rando phantoms for surface dose measurements. EBT3 films were cut in size of 2.5 x 2.5 cm2 and placed on the left side, right side and the center of larynx and then the films were irradiated with 6 MV photon beams. The measured doses were compared with TPS. The results of TPS calculations were found to be lower compared to the EBT3 film measurements at all selected points. The lack of surface dose calculation in TPS should be considered while evaluating the radiotherapy plans.

A comparative study of standard intensity-modulated radiotherapy and RapidArc planning techniques for ipsilateral and bilateral head and neck irradiation

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

Pursley, Jennifer, E-mail: jpursley@mgh.harvard.edu; Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA; Damato, Antonio L.

The purpose of this study was to investigate class solutions using RapidArc volumetric-modulated arc therapy (VMAT) planning for ipsilateral and bilateral head and neck (H&N) irradiation, and to compare dosimetric results with intensity-modulated radiotherapy (IMRT) plans. A total of 14 patients who received ipsilateral and 10 patients who received bilateral head and neck irradiation were retrospectively replanned with several volumetric-modulated arc therapy techniques. For ipsilateral neck irradiation, the volumetric-modulated arc therapy techniques included two 360° arcs, two 360° arcs with avoidance sectors around the contralateral parotid, two 260° or 270° arcs, and two 210° arcs. For bilateral neck irradiation, themore » volumetric-modulated arc therapy techniques included two 360° arcs, two 360° arcs with avoidance sectors around the shoulders, and 3 arcs. All patients had a sliding-window-delivery intensity-modulated radiotherapy plan that was used as the benchmark for dosimetric comparison. For ipsilateral neck irradiation, a volumetric-modulated arc therapy technique using two 360° arcs with avoidance sectors around the contralateral parotid was dosimetrically comparable to intensity-modulated radiotherapy, with improved conformity (conformity index = 1.22 vs 1.36, p < 0.04) and lower contralateral parotid mean dose (5.6 vs 6.8 Gy, p < 0.03). For bilateral neck irradiation, 3-arc volumetric-modulated arc therapy techniques were dosimetrically comparable to intensity-modulated radiotherapy while also avoiding irradiation through the shoulders. All volumetric-modulated arc therapy techniques required fewer monitor units than sliding-window intensity-modulated radiotherapy to deliver treatment, with an average reduction of 35% for ipsilateral plans and 67% for bilateral plans. Thus, for ipsilateral head and neck irradiation a volumetric-modulated arc therapy technique using two 360° arcs with avoidance sectors around the contralateral parotid is recommended. For bilateral neck irradiation, 2- or 3-arc techniques are dosimetrically comparable to intensity-modulated radiotherapy, but more work is needed to determine the optimal approaches by disease site.« less

A comparative study of standard intensity-modulated radiotherapy and RapidArc planning techniques for ipsilateral and bilateral head and neck irradiation.

PubMed

Pursley, Jennifer; Damato, Antonio L; Czerminska, Maria A; Margalit, Danielle N; Sher, David J; Tishler, Roy B

2017-01-01

The purpose of this study was to investigate class solutions using RapidArc volumetric-modulated arc therapy (VMAT) planning for ipsilateral and bilateral head and neck (H&N) irradiation, and to compare dosimetric results with intensity-modulated radiotherapy (IMRT) plans. A total of 14 patients who received ipsilateral and 10 patients who received bilateral head and neck irradiation were retrospectively replanned with several volumetric-modulated arc therapy techniques. For ipsilateral neck irradiation, the volumetric-modulated arc therapy techniques included two 360° arcs, two 360° arcs with avoidance sectors around the contralateral parotid, two 260° or 270° arcs, and two 210° arcs. For bilateral neck irradiation, the volumetric-modulated arc therapy techniques included two 360° arcs, two 360° arcs with avoidance sectors around the shoulders, and 3 arcs. All patients had a sliding-window-delivery intensity-modulated radiotherapy plan that was used as the benchmark for dosimetric comparison. For ipsilateral neck irradiation, a volumetric-modulated arc therapy technique using two 360° arcs with avoidance sectors around the contralateral parotid was dosimetrically comparable to intensity-modulated radiotherapy, with improved conformity (conformity index = 1.22 vs 1.36, p < 0.04) and lower contralateral parotid mean dose (5.6 vs 6.8Gy, p < 0.03). For bilateral neck irradiation, 3-arc volumetric-modulated arc therapy techniques were dosimetrically comparable to intensity-modulated radiotherapy while also avoiding irradiation through the shoulders. All volumetric-modulated arc therapy techniques required fewer monitor units than sliding-window intensity-modulated radiotherapy to deliver treatment, with an average reduction of 35% for ipsilateral plans and 67% for bilateral plans. Thus, for ipsilateral head and neck irradiation a volumetric-modulated arc therapy technique using two 360° arcs with avoidance sectors around the contralateral parotid is recommended. For bilateral neck irradiation, 2- or 3-arc techniques are dosimetrically comparable to intensity-modulated radiotherapy, but more work is needed to determine the optimal approaches by disease site. Copyright © 2017 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

COMPARISON OF THE PERIPHERAL DOSES FROM DIFFERENT IMRT TECHNIQUES FOR PEDIATRIC HEAD AND NECK RADIATION THERAPY.

PubMed

Toyota, Masahiko; Saigo, Yasumasa; Higuchi, Kenta; Fujimura, Takuya; Koriyama, Chihaya; Yoshiura, Takashi; Akiba, Suminori

2017-11-01

Intensity-modulated radiation therapy (IMRT) can deliver high and homogeneous doses to the target area while limiting doses to organs at risk. We used a pediatric phantom to simulate the treatment of a head and neck tumor in a child. The peripheral doses were examined for three different IMRT techniques [dynamic multileaf collimator (DMLC), segmental multileaf collimator (SMLC) and volumetric modulated arc therapy (VMAT)]. Peripheral doses were evaluated taking thyroid, breast, ovary and testis as the points of interest. Doses were determined using a radio-photoluminescence glass dosemeter, and the COMPASS system was used for three-dimensional dose evaluation. VMAT achieved the lowest peripheral doses because it had the highest monitor unit efficiency. However, doses in the vicinity of the irradiated field, i.e. the thyroid, could be relatively high, depending on the VMAT collimator angle. DMLC and SMLC had a large area of relatively high peripheral doses in the breast region. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Positron Emission Tomography-Guided, Focal-Dose Escalation Using Intensity-Modulated Radiotherapy for Head and Neck Cancer

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

Madani, Indira; Duthoy, Wim; Derie, Cristina R.N.

2007-05-01

Purpose: To assess the feasibility of intensity-modulated radiotherapy (IMRT) using positron emission tomography (PET)-guided dose escalation, and to determine the maximum tolerated dose in head and neck cancer. Methods and Materials: A Phase I clinical trial was designed to escalate the dose limited to the [{sup 18}-F]fluoro-2-deoxy-D-glucose positron emission tomography ({sup 18}F-FDG-PET)-delineated subvolume within the gross tumor volume. Positron emission tomography scanning was performed in the treatment position. Intensity-modulated radiotherapy with an upfront simultaneously integrated boost was employed. Two dose levels were planned: 25 Gy (level I) and 30 Gy (level II), delivered in 10 fractions. Standard IMRT was appliedmore » for the remaining 22 fractions of 2.16 Gy. Results: Between 2003 and 2005, 41 patients were enrolled, with 23 at dose level I, and 18 at dose level II; 39 patients completed the planned therapy. The median follow-up for surviving patients was 14 months. Two cases of dose-limiting toxicity occurred at dose level I (Grade 4 dermitis and Grade 4 dysphagia). One treatment-related death at dose level II halted the study. Complete response was observed in 18 of 21 (86%) and 13 of 16 (81%) evaluated patients at dose levels I and II (p < 0.7), respectively, with actuarial 1-year local control at 85% and 87% (p n.s.), and 1-year overall survival at 82% and 54% (p = 0.06), at dose levels I and II, respectively. In 4 of 9 patients, the site of relapse was in the boosted {sup 18}F-FDG-PET-delineated region. Conclusions: For head and neck cancer, PET-guided dose escalation appears to be well-tolerated. The maximum tolerated dose was not reached at the investigated dose levels.« less

Intensity-Modulated Radiation Therapy (IMRT) for Head and Neck Surgeons

PubMed Central

Gutiontov, Stanley I.; Shin, Edward J.; Lok, Benjamin; Lee, Nancy Y.; Cabanillas, Ruben

2016-01-01

The development of intensity-modulated radiation therapy has played a major role in improving outcomes and decreasing morbidity in head and neck cancer patients. This review addresses this vital modality with a focus on the important role of the head and neck surgeon. The technique as well as its benefits and points of caution are outlined, the definitions of tumor and treatment volumes are discussed, and the dose and fractionation are detailed. Following this are several sections dedicated to the role of the head and neck surgeon in the planning of both definitive and post-operative radiation therapy to the primary site and neck. There is a focus throughout on anatomic and surgical considerations; commonly encountered situations are illustrated. With a deeper understanding of this technique and their own pivotal contribution to target delineation, head and neck surgeons will be poised to expand their role and improve cancer care for their patients. PMID:26705685

Relative plan robustness of step-and-shoot vs rotational intensity–modulated radiotherapy on repeat computed tomographic simulation for weight loss in head and neck cancer

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

Thomson, David J.; The University of Manchester, Manchester Academic Health Science Centre, Institute of Cancer Sciences, Manchester; Beasley, William J.

Introduction: Interfractional anatomical alterations may have a differential effect on the dose delivered by step-and-shoot intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT). The increased degrees of freedom afforded by rotational delivery may increase plan robustness (measured by change in target volume coverage and doses to organs at risk [OARs]). However, this has not been evaluated for head and neck cancer. Materials and methods: A total of 10 patients who required repeat computed tomography (CT) simulation and replanning during head and neck IMRT were included. Step-and-shoot IMRT and VMAT plans were generated from the original planning scan. The initial andmore » second CT simulation scans were fused and targets/OAR contours transferred, reviewed, and modified. The plans were applied to the second CT scan and doses recalculated without repeat optimization. Differences between step-and-shoot IMRT and VMAT for change in target volume coverage and doses to OARs between first and second CT scans were compared by Wilcoxon signed rank test. Results: There were clinically relevant dosimetric changes between the first and the second CT scans for both the techniques (reduction in mean D{sub 95%} for PTV2 and PTV3, D{sub min} for CTV2 and CTV3, and increased mean doses to the parotid glands). However, there were no significant differences between step-and-shoot IMRT and VMAT for change in any target coverage parameter (including D{sub 95%} for PTV2 and PTV3 and D{sub min} for CTV2 and CTV3) or dose to any OARs (including parotid glands) between the first and the second CT scans. Conclusions: For patients with head and neck cancer who required replanning mainly due to weight loss, there were no significant differences in plan robustness between step-and-shoot IMRT and VMAT. This information is useful with increased clinical adoption of VMAT.« less

Electron intensity modulation for mixed-beam radiation therapy with an x-ray multi-leaf collimator

NASA Astrophysics Data System (ADS)

Weinberg, Rebecca

The current standard treatment for head and neck cancer at our institution uses intensity-modulated x-ray therapy (IMRT), which improves target coverage and sparing of critical structures by delivering complex fluence patterns from a variety of beam directions to conform dose distributions to the shape of the target volume. The standard treatment for breast patients is field-in-field forward-planned IMRT, with initial tangential fields and additional reduced-weight tangents with blocking to minimize hot spots. For these treatment sites, the addition of electrons has the potential of improving target coverage and sparing of critical structures due to rapid dose falloff with depth and reduced exit dose. In this work, the use of mixed-beam therapy (MBT), i.e., combined intensity-modulated electron and x-ray beams using the x-ray multi-leaf collimator (MLC), was explored. The hypothesis of this study was that addition of intensity-modulated electron beams to existing clinical IMRT plans would produce MBT plans that were superior to the original IMRT plans for at least 50% of selected head and neck and 50% of breast cases. Dose calculations for electron beams collimated by the MLC were performed with Monte Carlo methods. An automation system was created to facilitate communication between the dose calculation engine and the treatment planning system. Energy and intensity modulation of the electron beams was accomplished by dividing the electron beams into 2x2-cm2 beamlets, which were then beam-weight optimized along with intensity-modulated x-ray beams. Treatment plans were optimized to obtain equivalent target dose coverage, and then compared with the original treatment plans. MBT treatment plans were evaluated by participating physicians with respect to target coverage, normal structure dose, and overall plan quality in comparison with original clinical plans. The physician evaluations did not support the hypothesis for either site, with MBT selected as superior in 1 out of the 15 head and neck cases (p=1) and 6 out of 18 breast cases (p=0.95). While MBT was not shown to be superior to IMRT, reductions were observed in doses to critical structures distal to the target along the electron beam direction and to non-target tissues, at the expense of target coverage and dose homogeneity.

Influence of jaw tracking in intensity-modulated and volumetric-modulated arc radiotherapy for head and neck cancers: a dosimetric study.

PubMed

Mani, Karthick Raj; Upadhayay, Sagar; Das, K J Maria

2017-03-01

To Study the dosimetric advantage of the Jaw tracking technique in intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) for Head and Neck Cancers. We retrospectively selected 10 previously treated head and neck cancer patients stage (T1/T2, N1, M0) in this study. All the patients were planned for IMRT and VMAT with simultaneous integrated boost technique. IMRT and VMAT plans were performed with jaw tracking (JT) and with static jaw (SJ) technique by keeping the same constraints and priorities for a particular patient. Target conformity, dose to the critical structures and low dose volumes were recorded and analyzed for IMRT and VMAT plans with and without JT for all the patients. The conformity index average of all patients followed by standard deviation ([Formula: see text] ± [Formula: see text]) of the JT-IMRT, SJ-IMRT, JT-VMAT, and SJ-VMAT were 1.72 ± 0.56, 1.67 ± 0.57, 1.83 ± 0.65, and 1.85 ± 0.64, and homogeneity index were 0.059 ± 0.05, 0.064 ± 0.05, 0.064 ± 0.04, and 0.064 ± 0.05. JT-IMRT shows significant mean reduction in right parotid and left parotid shows of 7.64% (p < 0.001) and 7.45% (p < 0.001) compare to SJ-IMRT. JT-IMRT plans also shows considerable dose reduction to thyroid, inferior constrictors, spinal cord and brainstem compared to the SJ-IMRT plans. Significant dose reductions were observed for critical structure in the JT-IMRT compared to SJ-IMRT technique. In JT-VMAT plans dose reduction to the critical structure were not significant compared to the SJ-IMRT due to relatively lesser monitor units.

Technique for comprehensive head and neck irradiation using 3-dimensional conformal proton therapy

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

McDonald, Mark W., E-mail: markmcdonaldmd@gmail.com; Indiana University Health Proton Therapy Center, Bloomington, IN; Walter, Alexander S.

2015-01-01

Owing to the technical and logistical complexities of matching photon and proton treatment modalities, we developed and implemented a technique of comprehensive head and neck radiation using 3-dimensional (3D) conformal proton therapy. A monoisocentric technique was used with a 30-cm snout. Cervical lymphatics were treated with 3 fields: a posterior-anterior field with a midline block and a right and a left posterior oblique field. The matchline of the 3 cervical nodal fields with the primary tumor site fields was staggered by 0.5 cm. Comparative intensity-modulated photon plans were later developed for 12 previously treated patients to provide equivalent target coverage,more » while matching or improving on the proton plans' sparing of organs at risk (OARs). Dosimetry to OARs was evaluated and compared by treatment modality. Comprehensive head and neck irradiation using proton therapy yielded treatment plans with significant dose avoidance of the oral cavity and midline neck structures. When compared with the generated intensity-modulated radiation therapy (IMRT) plans, the proton treatment plans yielded statistically significant reductions in the mean and integral radiation dose to the oral cavity, larynx, esophagus, and the maximally spared parotid gland. There was no significant difference in mean dose to the lesser-spared parotid gland by treatment modality or in mean or integral dose to the spared submandibular glands. A technique for cervical nodal irradiation using 3D conformal proton therapy with uniform scanning was developed and clinically implemented. Use of proton therapy for cervical nodal irradiation resulted in large volume of dose avoidance to the oral cavity and low dose exposure to midline structures of the larynx and the esophagus, with lower mean and integral dose to assessed OARs when compared with competing IMRT plans.« less

Impact of Node Negative Target Volume Delineation on Contralateral Parotid Gland Dose Sparing Using IMRT in Head and Neck Cancer.

PubMed

Magnuson, William J; Urban, Erich; Bayliss, R Adam; Harari, Paul M

2015-06-01

There is considerable practice variation in treatment of the node negative (N0) contralateral neck in patients with head and neck cancer. In this study, we examined the impact of N0 neck target delineation volume on radiation dose to the contralateral parotid gland. Following institutional review board approval, 12 patients with head and neck cancer were studied. All had indications for treatment of the N0 neck, such as midline base of tongue or soft palate extension or advanced ipsilateral nodal disease. The N0 neck volumes were created using the Radiation Therapy Oncology Group head and neck contouring atlas. The physician-drawn N0 neck clinical target volume (CTV) was expanded by 25% to 200% to generate volume variation, followed by a 3-mm planning target volume (PTV) expansion. Surrounding organs at risk were contoured and complete intensity-modulated radiation therapy plans were generated for each N0 volume expansion. The median N0 target volume drawn by the radiation oncologist measured 93 cm(3) (range 71-145). Volumetric expansion of the N0 CTV by 25% to 200% increased the resultant mean dose to the contralateral parotid gland by 1.4 to 8.5 Gray (Gy). For example, a 4.1-mm increase in the N0 neck CTV translated to a 2.0-Gy dose increase to the parotid, 7.4 mm to a 4.5 Gy dose increase, and 12.5 mm to an 8.5 Gy dose increase, respectively. The treatment volume designated for the N0 neck has profound impact on resultant dose to the contralateral parotid gland. Variations of up to 15 mm are routine across physicians in target contouring, reflecting individual preference and training expertise. Depending on the availability of immobilization and image guidance techniques, experts commonly recommend 3 to 10 mm margin expansions to generate the PTV. Careful attention to the original volume of the N0 neck CTV, as well as expansion margins, is important in achieving effective contralateral gland sparing to reduce the resultant xerostomia and dysguesia that may ensue after radiotherapy. © The Author(s) 2014.

A case study of IMRT planning (Plan B) subsequent to a previously treated IMRT plan (Plan A)

NASA Astrophysics Data System (ADS)

Cao, F.; Leong, C.; Schroeder, J.; Lee, B.

2014-03-01

Background and purpose: Treatment of the contralateral neck after previous ipsilateral intensity modulated radiation therapy (IMRT) for head and neck cancer is a challenging problem. We have developed a technique that limits the cumulative dose to the spinal cord and brainstem while maximizing coverage of a planning target volume (PTV) in the contralateral neck. Our case involves a patient with right tonsil carcinoma who was given ipsilateral IMRT with 70Gy in 35 fractions (Plan A). A left neck recurrence was detected 14 months later. The patient underwent a neck dissection followed by postoperative left neck radiation to a dose of 66 Gy in 33 fractions (Plan B). Materials and Methods: The spinal cord-brainstem margin (SCBM) was defined as the spinal cord and brainstem with a 1.0 cm margin. Plan A was recalculated on the postoperative CT scan but the fluence outside of SCBM was deleted. A further modification of Plan A resulted in a base plan that was summed with Plan B to evaluate the cumulative dose received by the spinal cord and brainstem. Plan B alone was used to evaluate for coverage of the contralateral neck PTV. Results: The maximum cumulative doses to the spinal cord with 0.5cm margin and brainstem with 0.5cm margin were 51.96 Gy and 45.60 Gy respectively. For Plan B, 100% of the prescribed dose covered 95% of PTVb1. Conclusion: The use of a modified ipsilateral IMRT plan as a base plan is an effective way to limit the cumulative dose to the spinal cord and brainstem while enabling coverage of a PTV in the contralateral neck.

Skin dose for head and neck cancer patients treated with intensity-modulated radiation therapy(IMRT)

NASA Astrophysics Data System (ADS)

Fu, Hsiao-Ju; Li, Chi-Wei; Tsai, Wei-Ta; Chang, Chih-Chia; Tsang, Yuk-Wah

2017-11-01

The reliability of thermoluminescent dosimeters (ultrathin TLD) and ISP Gafchromic EBT2 film to measure the surface dose in phantom and the skin dose in head-and-neck patients treated with intensity-modulated radiation therapy technique(IMRT) is the research focus. Seven-field treatment plans with prescribed dose of 180 cGy were performed on Eclipse treatment planning system which utilized pencil beam calculation algorithm(PBC). In calibration tests, the variance coefficient of the ultrathin TLDs were within 3%. The points on the calibration curve of the Gafchromic film was within 1% variation. Five measurements were taken on phantom using ultrathin TLD and EBT2 film respectively. The measured mean surface doses between ultrathin TLD or EBT2 film were within 5% deviation. Skin doses of 6 patients were measured for initial 5 fractions and the mean dose per-fraction was calculated. If the extrapolated doses for 30 fractions were below 4000 cGy, the skin reaction grading observed according to Radiation Therapy Oncology Group (RTOG) was either grade 1 or grade 2. If surface dose exceeded 5000 cGy in 32 fractions, then grade 3 skin reactions were observed.

Three-Dimensional Planning in Maxillofacial Fracture Surgery: Computer-Aided Design/Computer-Aided Manufacture Surgical Splints by Integrating Cone Beam Computerized Tomography Images Into Multislice Computerized Tomography Images.

PubMed

Ren, Jiayin; Zhou, Zhongwei; Li, Peng; Tang, Wei; Guo, Jixiang; Wang, Hu; Tian, Weidong

2016-09-01

This study aimed to evaluate an innovative workflow for maxillofacial fracture surgery planning and surgical splint designing. The maxillofacial multislice computerized tomography (MSCT) data and dental cone beam computerized tomography (CBCT) data both were obtained from 40 normal adults and 58 adults who suffered fractures. The each part of the CBCT dentition image was registered into MSCT image by the use of the iterative closest point algorithm. Volume evaluation of the virtual splints that were designed by the registered MSCT images and MSCT images of the same object was performed. Eighteen patients (group 1) were operated without any splint. Twenty-one (group 2) and 19 patients (group 3) used the splints designed according to the MSCT images and registered MSCT images, respectively. The authors' results showed that the mean errors between the 2 models ranged from 0.53 to 0.92 mm and the RMS errors ranged from 0.38 to 0.69 mm in fracture patients. The mean errors between the 2 models ranged from 0.47 to 0.85 mm and the RMS errors ranged from 0.33 to 0.71 mm in normal adults. 72.22% patients in group 1 recovered occlusion. 85.71% patients in group 2, and 94.73% patients in group 3 reconstructed occlusion. There was a statistically significant difference between the MSCT images based splints' volume and the registered MSCT splints' volume in patients (P <0.05). The MSCT images based splints' volume was statistically significantly distinct from the registered MSCT splints' volume in normal adults (P <0.05). There was a statistically significant difference between the MSCT images based splints' volume and the registered MSCT splints' volume in patients and normal adults (P <0.05). The occlusion recovery rate of group 3 was better than that of group 1 and group 2. The way of integrating CBCT images into MSCT images for splints designing was feasible. The volume of the splints designed by MSCT images tended to be smaller than the splints designed by the integrated MSCT images. The patients operated with splints tended to regain occlusion. The patients who were operated with the splints which were designed according to registered MSCT images tended to get occlusal recovered.

CT dose modulation using automatic exposure control in whole-body PET/CT: effects of scout imaging direction and arm positioning.

PubMed

Inoue, Yusuke; Nagahara, Kazunori; Kudo, Hiroko; Itoh, Hiroyasu

2018-01-01

Automatic exposure control (AEC) modulates tube current and consequently X-ray exposure in CT. We investigated the behavior of AEC systems in whole-body PET/CT. CT images of a whole-body phantom were acquired using AEC on two scanners from different manufactures. The effects of scout imaging direction and arm positioning on dose modulation were evaluated. Image noise was assessed in the chest and upper abdomen. On one scanner, AEC using two scout images in the posteroanterior (PA) and lateral (Lat) directions provided relatively constant image noise along the z-axis with the arms at the sides. Raising the arms increased tube current in the head and neck and decreased it in the body trunk. Image noise increased in the upper abdomen, suggesting excessive reduction in radiation exposure. AEC using the PA scout alone strikingly increased tube current and reduced image noise in the shoulder. Raising the arms did not substantially influence dose modulation and decreased noise in the abdomen. On the other scanner, AEC using the PA scout alone or Lat scout alone resulted in similar dose modulation. Raising the arms increased tube current in the head and neck and decreased it in the trunk. Image noise was higher in the upper abdomen than in the middle and lower chest, and was not influenced by arm positioning. CT dose modulation using AEC may vary greatly depending on scout direction. Raising the arms tended to decrease radiation exposure; however, the effect depends on scout direction and the AEC system.

[Brachytherapy for head and neck cancers].

PubMed

Peiffert, D; Coche-Dequéant, B; Lapeyre, M; Renard, S

2018-05-29

The main indications of the brachytherapy of head and neck cancers are the limited tumours of the lip, the nose, the oral cavity and the oropharynx. Nasopharynx tumours are nowadays treated by intensity-modulated radiotherapy. This technique can be exclusive, associated with external radiotherapy or postoperative. It can also be a salvage treatment for the second primaries in previously irradiated areas. If the low dose rate brachytherapy rules remain the reference, the pulse dose rate technique allows the prescription of the dose rate and the optimisation of the dose distribution. Results of high dose rate brachytherapy are now published. This paper reports the recommendations of the Gec-ESTRO, published in 2017, and takes into account the data of the historical low dose rate series, and is upgraded with the pulsed-dose rate and high dose rate series. Copyright © 2018. Published by Elsevier SAS.

The potential of multi-slice computed tomography based volumetry for demonstrating reverse remodeling induced by cardiac resynchronization therapy.

PubMed

Langer, Christoph; Schroeder, Janina; Peterschroeder, Andreas; Vaske, Bernhard; Faber, Lothar; Welge, Dirk; Niethammer, Matthias; Lamp, Barbara; Butz, Thomas; Bitter, Thomas; Oldenburg, Olaf; Horstkotte, Dieter

2010-07-01

Multi-slice computed tomography (MSCT) was proved to provide precise cardiac volumetric assessment. Cardiac resynchronization therapy (CRT) is an effective treatment for selected patients with heart failure and reduced ejection fraction (HFREF). In HFREF patients we investigated the potential of MSCT based wall motion analysis in order to demonstrate CRT-induced reversed remodeling. Besides six patients with normal cardiac pump function serving as control group seven HFREF patients underwent contrast enhanced MSCT before and after CRT. Short cardiac axis views of the left ventricle (LV) in end-diastole (ED) and end-systole (ES) served for planimetry. Pre- and post-CRT MSCT based volumetry was compared with 2D echo. To demonstrate CRT-induced reverse remodeling, MSCT based multi-segment color-coded polar maps were introduced. With regard to the HFREF patients pre-CRT MSCT based volumetry correlated with 2D echo data for LV-EDV (MSCT 278.3+/-75.0mL vs. echo 274.4+/-85.6mL) r=0.380, p=0.401, LV-ESV (MSCT 226.7+/-75.4mL vs. echo 220.1+/-74.0mL) r=0.323, p=0.479 and LV-EF (MSCT 20.2+/-8.8% vs. echo 20.0+/-11.9%) r=0.617, p=0.143. Post-CRT MSCT correlated well with 2D echo: LV-EDV (MSCT 218.9+/-106.4mL vs. echo 188.7+/-93.1mL) r=0.87, p=0.011, LV-ESV (MSCT 145+/-71.5mL vs. echo 125.6+/-78mL) r=0.84, p=0.018 and LV-EF (MSCT 29.6+/-11.3mL vs. echo 38.6+/-14.6mL) r=0.89, p=0.007. There was a significant increase of the mid-ventricular septum in terms of absolute LV wall thickening of the responders (pre 0.9+/-2.1mm vs. post 3.3+/-2.2mm; p<0.0005). MSCT based volumetry involving multi-segment color-coded polar maps offers wall motion analysis to demonstrate CRT-induced reverse remodeling which needs to be further validated. 2010 Elsevier Ltd. All rights reserved.

Comparison between cone-beam and multislice computed tomography depicting mandibular neurovascular canal structures.

PubMed

Naitoh, Munetaka; Nakahara, Kino; Suenaga, Yutaka; Gotoh, Kenichi; Kondo, Shintaro; Ariji, Eiichiro

2010-01-01

The most common diagnostic imaging modalities for cross-sectional imaging in dental implant planning are currently cone-beam computed tomography (CBCT) and multislice CT (MSCT). However, clinical differences between CBCT and MSCT in this task have not been fully clarified. In this investigation, the detection of fine anatomical structures in the mandible was assessed and compared between CBCT and MSCT images. The sample consisted of 28 patients who had undergone CBCT and MSCT. The bifid mandibular canal in the mandibular ramus, accessory mental and buccal foramina, and median and lateral lingual bony canals were observed in 2-D images, and the findings were compared between CBCT and MSCT. Four of 19 canals observed in CBCT were not observed in MSCT images. Three accessory mental foramina in 2 patients and 28 lateral lingual bony canals in 18 patients were observed consistently using the two methods. Depiction of fine anatomic features in the mandible associated with neurovascular structures is consistent between CBCT and MSCT images. Copyright 2010 Mosby, Inc. All rights reserved.

Brachial Plexus-Associated Neuropathy After High-Dose Radiation Therapy for Head-and-Neck Cancer

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

Chen, Allen M., E-mail: allen.chen@ucdmc.ucdavis.edu; Hall, William H.; Li, Judy

2012-09-01

Purpose: To identify clinical and treatment-related predictors of brachial plexus-associated neuropathies after radiation therapy for head-and-neck cancer. Methods and Materials: Three hundred thirty patients who had previously completed radiation therapy for head-and-neck cancer were prospectively screened using a standardized instrument for symptoms of neuropathy thought to be related to brachial plexus injury. All patients were disease-free at the time of screening. The median time from completion of radiation therapy was 56 months (range, 6-135 months). One-hundred fifty-five patients (47%) were treated by definitive radiation therapy, and 175 (53%) were treated postoperatively. Radiation doses ranged from 50 to 74 Gy (median,more » 66 Gy). Intensity-modulated radiation therapy was used in 62% of cases, and 133 patients (40%) received concurrent chemotherapy. Results: Forty patients (12%) reported neuropathic symptoms, with the most common being ipsilateral pain (50%), numbness/tingling (40%), motor weakness, and/or muscle atrophy (25%). When patients with <5 years of follow-up were excluded, the rate of positive symptoms increased to 22%. On univariate analysis, the following factors were significantly associated with brachial plexus symptoms: prior neck dissection (p = 0.01), concurrent chemotherapy (p = 0.01), and radiation maximum dose (p < 0.001). Cox regression analysis confirmed that both neck dissection (p < 0.001) and radiation maximum dose (p < 0.001) were independently predictive of symptoms. Conclusion: The incidence of brachial plexus-associated neuropathies after radiation therapy for head-and-neck cancer may be underreported. In view of the dose-response relationship identified, limiting radiation dose to the brachial plexus should be considered when possible.« less

In vivo dose perturbation effects of metallic dental alloys during head and neck irradiation with intensity modulated radiation therapy.

PubMed

Fuller, Clifton D; Diaz, Irma; Cavanaugh, Sean X; Eng, Tony Y

2004-07-01

A patient with base of tongue squamous sell carcinoma, with significant CT artifact-inducing metallic alloy, non-removable dental restorations in both the mandible and maxilla was identified. Simultaneous with IMRT treatment, thermoluminescent dosimeters (TLDs) were placed in the oral cavity. After a series of three treatments, the data from the TLDs and software calculations were analyzed. Analysis of mean in vivo TLD dosimetry reveals differentials from software predicted dose calculation that fall within acceptable dose variation limits. IMRT dose calculation software is a relatively accurate predictor of dose attenuation and augmentation due to dental alloys within the treatment volume, as measured by intra-oral thermoluminescent dosimetry. IMRT represents a safe and effective methodology to treat patients with non-removable metallic dental work who have head and neck cancer.

The dosimetric effects of tissue heterogeneities in intensity-modulated radiation therapy (IMRT) of the head and neck

NASA Astrophysics Data System (ADS)

Al-Hallaq, H. A.; Reft, C. S.; Roeske, J. C.

2006-03-01

The dosimetric effects of bone and air heterogeneities in head and neck IMRT treatments were quantified. An anthropomorphic RANDO phantom was CT-scanned with 16 thermoluminescent dosimeter (TLD) chips placed in and around the target volume. A standard IMRT plan generated with CORVUS was used to irradiate the phantom five times. On average, measured dose was 5.1% higher than calculated dose. Measurements were higher by 7.1% near the heterogeneities and by 2.6% in tissue. The dose difference between measurement and calculation was outside the 95% measurement confidence interval for six TLDs. Using CORVUS' heterogeneity correction algorithm, the average difference between measured and calculated doses decreased by 1.8% near the heterogeneities and by 0.7% in tissue. Furthermore, dose differences lying outside the 95% confidence interval were eliminated for five of the six TLDs. TLD doses recalculated by Pinnacle3's convolution/superposition algorithm were consistently higher than CORVUS doses, a trend that matched our measured results. These results indicate that the dosimetric effects of air cavities are larger than those of bone heterogeneities, thereby leading to a higher delivered dose compared to CORVUS calculations. More sophisticated algorithms such as convolution/superposition or Monte Carlo should be used for accurate tailoring of IMRT dose in head and neck tumours.

Effect of Edge-Preserving Adaptive Image Filter on Low-Contrast Detectability in CT Systems: Application of ROC Analysis

PubMed Central

Okumura, Miwa; Ota, Takamasa; Kainuma, Kazuhisa; Sayre, James W.; McNitt-Gray, Michael; Katada, Kazuhiro

2008-01-01

Objective. For the multislice CT (MSCT) systems with a larger number of detector rows, it is essential to employ dose-reduction techniques. As reported in previous studies, edge-preserving adaptive image filters, which selectively eliminate only the noise elements that are increased when the radiation dose is reduced without affecting the sharpness of images, have been developed. In the present study, we employed receiver operating characteristic (ROC) analysis to assess the effects of the quantum denoising system (QDS), which is an edge-preserving adaptive filter that we have developed, on low-contrast resolution, and to evaluate to what degree the radiation dose can be reduced while maintaining acceptable low-contrast resolution. Materials and Methods. The low-contrast phantoms (Catphan 412) were scanned at various tube current settings, and ROC analysis was then performed for the groups of images obtained with/without the use of QDS at each tube current to determine whether or not a target could be identified. The tube current settings for which the area under the ROC curve (Az value) was approximately 0.7 were determined for both groups of images with/without the use of QDS. Then, the radiation dose reduction ratio when QDS was used was calculated by converting the determined tube current to the radiation dose. Results. The use of the QDS edge-preserving adaptive image filter allowed the radiation dose to be reduced by up to 38%. Conclusion. The QDS was found to be useful for reducing the radiation dose without affecting the low-contrast resolution in MSCT studies. PMID:19043565

Phase II Trial of Hyperfractionated Intensity-Modulated Radiation Therapy and Concurrent Weekly Cisplatin for Stage III and IVa Head-and-Neck Cancer

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

Maguire, Patrick D., E-mail: pmaguire@nhroc.co; Papagikos, Michael; Hamann, Sue

2011-03-15

Purpose: To investigate a novel chemoradiation regimen designed to maximize locoregional control (LRC) and minimize toxicity for patients with advanced head-and-neck squamous cell carcinoma (HNSCC). Methods and Materials: Patients received hyperfractionated intensity modulated radiation therapy (HIMRT) in 1.25-Gy fractions b.i.d. to 70 Gy to high-risk planning target volume (PTV). Intermediate and low-risk PTVs received 60 Gy and 50 Gy, at 1.07, and 0.89 Gy per fraction, respectively. Concurrent cisplatin 33 mg/m{sup 2}/week was started Week 1. Patients completed the Quality of Life Radiation Therapy Instrument pretreatment (PRE), at end of treatment (EOT), and at 1, 3, 6, 9, and 12more » months. Overall survival (OS), progression-free (PFS), LRC, and toxicities were assessed. Results: Of 39 patients, 30 (77%) were alive without disease at median follow-up of 37.5 months. Actuarial 3-year OS, PFS, and LRC were 80%, 82%, and 87%, respectively. No failures occurred in the electively irradiated neck and there were no isolated neck failures. Head and neck QOL was significantly worse in 18 of 35 patients (51%): mean 7.8 PRE vs. 3.9 EOT. By month 1, H and N QOL returned near baseline (mean 6.2, SD = 1.7). The most common acute Grade 3+ toxicities were mucositis (38%), fatigue (28%), dysphagia (28%), and leukopenia (26%). Conclusions: Hyperfractionated IMRT with low-dose weekly cisplatin resulted in good LRC with acceptable toxicity and QOL. Lack of elective nodal failures despite very low dose per fraction has led to an attempt to further minimize toxicity by reducing elective nodal doses in our subsequent protocol.« less

SU-E-T-624: Quantitative Evaluation of 2D Versus 3D Dosimetry for Stereotactic Volumetric Modulated Arc Delivery Using COMPASS

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

Vikraman, S; Karrthick, K; Rajesh, T

2014-06-15

Purpose: The purpose of this study was to evaluate quantitatively 2D versus 3D dosimetry for stereotactic volumetric modulated arc delivery using COMPASS with 2D array. Methods: Twenty-five patients CT images and RT structures of different sites like brain, head and neck, thorax, abdomen and spine were taken from Multiplan planning system for this study. All these patients underwent radical stereotactic treatment in Cyberknife. For each patient, linac based VMAT stereotactic plans were generated in Monaco TPS v 3.1 using Elekta Beam Modulator MLC. Dose prescription was in the range of 5-20Gy/fraction.TPS calculated VMAT plan delivery accuracy was quantitatively evaluated withmore » COMPASS measured dose and calculated dose based on DVH metrics. In order to ascertain the potential of COMPASS 3D dosimetry for stereotactic plan delivery, 2D fluence verification was performed with MatriXX using Multicube. Results: For each site, D{sub 9} {sub 5} was achieved with 100% of prescription dose with maximum 0.05SD. Conformity index (CI) was observed closer to 1.15 in all cases. Maximum deviation of 2.62 % was observed for D{sub 9} {sub 5} when compared TPS versus COMPASS measured. Considerable deviations were observed in head and neck cases compare to other sites. The maximum mean and standard deviation for D{sub 9} {sub 5}, average target dose and average gamma were -0.78±1.72, -1.10±1.373 and 0.39±0.086 respectively. Numbers of pixels passing 2D fluence verification were observed as a mean of 99.36% ±0.455 SD with 3% dose difference and 3mm DTA. For critical organs in head and neck cases, significant dose differences were observed in 3D dosimetry while the target doses were matched well within limit in both 2D and 3D dosimetry. Conclusion: The quantitative evaluations of 2D versus 3D dosimetry for stereotactic volumetric modulated plans showed the potential of highlighting the delivery errors. This study reveals that COMPASS 3D dosimetry is an effective tool for patient specific quality assurance compared to 2D fluence verification.« less

Correlation of Osteoradionecrosis and Dental Events With Dosimetric Parameters in Intensity-Modulated Radiation Therapy for Head-and-Neck Cancer

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

Gomez, Daniel R., E-mail: dgomez@mdanderson.org; Estilo, Cherry L.; Wolden, Suzanne L.

Purpose: Osteoradionecrosis (ORN) is a known complication of radiation therapy to the head and neck. However, the incidence of this complication with intensity-modulated radiation therapy (IMRT) and dental sequelae with this technique have not been fully elucidated. Methods and Materials: From December 2000 to July 2007, 168 patients from our institution have been previously reported for IMRT of the oral cavity, nasopharynx, larynx/hypopharynx, sinus, and oropharynx. All patients underwent pretreatment dental evaluation, including panoramic radiographs, an aggressive fluoride regimen, and a mouthguard when indicated. The median maximum mandibular dose was 6,798 cGy, and the median mean mandibular dose was 3,845more » cGy. Patient visits were retrospectively reviewed for the incidence of ORN, and dental records were reviewed for the development of dental events. Univariate analysis was then used to assess the effect of mandibular and parotid gland dosimetric parameters on dental endpoints. Results: With a median clinic follow-up of 37.4 months (range, 0.8-89.6 months), 2 patients, both with oral cavity primaries, experienced ORN. Neither patient had preradiation dental extractions. The maximum mandibular dose and mean mandibular dose of the 2 patients were 7,183 and 6,828 cGy and 5812 and 5335 cGy, respectively. In all, 17% of the patients (n = 29) experienced a dental event. A mean parotid dose of >26 Gy was predictive of a subsequent dental caries, whereas a maximum mandibular dose >70 Gy and a mean mandibular dose >40 Gy were correlated with dental extractions after IMRT. Conclusions: ORN is rare after head-and-neck IMRT, but is more common with oral cavity primaries. Our results suggest different mechanisms for radiation-induced caries versus extractions.« less

Correlation of osteoradionecrosis and dental events with dosimetric parameters in intensity-modulated radiation therapy for head-and-neck cancer.

PubMed

Gomez, Daniel R; Estilo, Cherry L; Wolden, Suzanne L; Zelefsky, Michael J; Kraus, Dennis H; Wong, Richard J; Shaha, Ashok R; Shah, Jatin P; Mechalakos, James G; Lee, Nancy Y

2011-11-15

Osteoradionecrosis (ORN) is a known complication of radiation therapy to the head and neck. However, the incidence of this complication with intensity-modulated radiation therapy (IMRT) and dental sequelae with this technique have not been fully elucidated. From December 2000 to July 2007, 168 patients from our institution have been previously reported for IMRT of the oral cavity, nasopharynx, larynx/hypopharynx, sinus, and oropharynx. All patients underwent pretreatment dental evaluation, including panoramic radiographs, an aggressive fluoride regimen, and a mouthguard when indicated. The median maximum mandibular dose was 6,798 cGy, and the median mean mandibular dose was 3,845 cGy. Patient visits were retrospectively reviewed for the incidence of ORN, and dental records were reviewed for the development of dental events. Univariate analysis was then used to assess the effect of mandibular and parotid gland dosimetric parameters on dental endpoints. With a median clinic follow-up of 37.4 months (range, 0.8-89.6 months), 2 patients, both with oral cavity primaries, experienced ORN. Neither patient had preradiation dental extractions. The maximum mandibular dose and mean mandibular dose of the 2 patients were 7,183 and 6,828 cGy and 5812 and 5335 cGy, respectively. In all, 17% of the patients (n = 29) experienced a dental event. A mean parotid dose of >26 Gy was predictive of a subsequent dental caries, whereas a maximum mandibular dose >70 Gy and a mean mandibular dose >40 Gy were correlated with dental extractions after IMRT. ORN is rare after head-and-neck IMRT, but is more common with oral cavity primaries. Our results suggest different mechanisms for radiation-induced caries versus extractions. Copyright © 2011 Elsevier Inc. All rights reserved.

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

Casey, K; Wong, P; Tung, S

Purpose: To quantify the dosimetric impact of interfractional shoulder motion on targets in the low neck for head and neck patients treated with volume modulated arc therapy (VMAT). Methods: Three patients with head and neck cancer were selected. All three required treatment to nodal regions in the low neck in addition to the primary tumor. The patients were immobilized during simulation and treatment with a custom thermoplastic mask covering the head and shoulders. One VMAT plan was created for each patient utilizing two full 360° arcs. A second plan was created consisting of two superior VMAT arcs matched to anmore » inferior static AP supraclavicular field. A CT-on-rails alignment verification was performed weekly during each patient's treatment course. The weekly CT images were registered to the simulation CT and the target contours were deformed and applied to the weekly CT. The two VMAT plans were copied to the weekly CT datasets and recalculated to obtain the dose to the low neck contours. Results: The average observed shoulder position shift in any single dimension relative to simulation was 2.5 mm. The maximum shoulder shift observed in a single dimension was 25.7 mm. Low neck target mean doses, normalized to simulation and averaged across all weekly recalculations were 0.996, 0.991, and 1.033 (Full VMAT plan) and 0.986, 0.995, and 0.990 (Half-Beam VMAT plan) for the three patients, respectively. The maximum observed deviation in target mean dose for any individual weekly recalculation was 6.5%, occurring with the Full VMAT plan for Patient 3. Conclusion: Interfractional variation in dose to low neck nodal regions was quantified for three head and neck patients treated with VMAT. Mean dose was 3.3% higher than planned for one patient using a Full VMAT plan. A Half-Beam technique is likely a safer choice when treating the supraclavicular region with VMAT.« less

Dose rate mapping of VMAT treatments

NASA Astrophysics Data System (ADS)

Podesta, Mark; Antoniu Popescu, I.; Verhaegen, Frank

2016-06-01

Human tissues exhibit a varying response to radiation dose depending on the dose rate and fractionation scheme used. Dose rate effects have been reported for different radiations, and tissue types. The literature indicates that there is not a significant difference in response for low-LET radiation when using dose rates between 1 Gy min-1 and 12 Gy min-1 but lower dose rates have an observable sparing effect on tissues and a differential effect between tissues. In intensity-modulated radiotherapy such as volumetric modulated arc therapy (VMAT) the dose can be delivered with a wide range of dose rates. In this work we developed a method based on time-resolved Monte Carlo simulations to quantify the dose rate frequency distribution for clinical VMAT treatments for three cancer sites, head and neck, lung, and pelvis within both planning target volumes (PTV) and normal tissues. The results show a wide range of dose rates are used to deliver dose in VMAT and up to 75% of the PTV can have its dose delivered with dose rates  <1 Gy min-1. Pelvic plans on average have a lower mean dose rate within the PTV than lung or head and neck plans but a comparable mean dose rate within the organs at risk. Two VMAT plans that fulfil the same dose objectives and constraints may be delivered with different dose rate distributions, particularly when comparing single arcs to multiple arc plans. It is concluded that for dynamic plans, the dose rate range used varies to a larger degree than previously assumed. The effect of the dose rate range in VMAT on clinical outcome is unknown.

SU-E-T-764: Track Repeating Algorithm for Proton Therapy Applied to Intensity Modulated Proton Therapy for Head-And-Neck Patients

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

Yepes, P; Mirkovic, D; Mohan, R

Purpose: To determine the suitability of fast Monte Carlo techniques for dose calculation in particle therapy based on track-repeating algorithm for Intensity Modulated Proton Therapy, IMPT. The application of this technique will make possible detailed retrospective studies of large cohort of patients, which may lead to a better determination of Relative Biological Effects from the analysis of patient data. Methods: A cohort of six head-and-neck patients treated at the University of Texas MD Anderson Cancer Center with IMPT were utilized. The dose distributions were calculated with the standard Treatment Plan System, TPS, MCNPX, GEANT4 and FDC, a fast track-repeating algorithmmore » for proton therapy for the verification and the patient plans. FDC is based on a GEANT4 database of trajectories of protons in a water. The obtained dose distributions were compared to each other utilizing the g-index criteria for 3mm-3% and 2mm-2%, for the maximum spatial and dose differences. The γ-index was calculated for voxels with a dose at least 10% of the maximum delivered dose. Dose Volume Histograms are also calculated for the various dose distributions. Results: Good agreement between GEANT4 and FDC is found with less than 1% of the voxels with a γ-index larger than 1 for 2 mm-2%. The agreement between MCNPX with FDC is within the requirements of clinical standards, even though it is slightly worse than the comparison with GEANT4.The comparison with TPS yielded larger differences, what is also to be expected because pencil beam algorithm do not always performed well in highly inhomogeneous areas like head-and-neck. Conclusion: The good agreement between a track-repeating algorithm and a full Monte Carlo for a large cohort of patients and a challenging, site like head-and-neck, opens the path to systematic and detailed studies of large cohorts, which may yield better understanding of biological effects.« less

Intensity-modulated radiotherapy in the standard management of head and neck cancer: promises and pitfalls.

PubMed

Mendenhall, William M; Amdur, Robert J; Palta, Jatinder R

2006-06-10

The purpose of this article is to review the role of intensity-modulated radiotherapy (IMRT) in the standard management of patients with head and neck cancer through a critical review of the pertinent literature. IMRT may result in a dose distribution that is more conformal than that achieved with three-dimensional conformal radiotherapy (3D CRT), allowing dose reduction to normal structures and thus decreasing toxicity and possibly enhancing locoregional control through dose escalation. Disadvantages associated with IMRT include increased risk of a marginal miss, decreased dose homogeneity, increased total body dose, and increased labor and expense. Outcomes data after IMRT are limited, and follow-up is relatively short. Locoregional control rates appear to be comparable to those achieved with 3D CRT and, depending on the location and extent of the tumor, late toxicity may be lower. Despite limited data on clinical outcomes, IMRT has been widely adopted as a standard technique in routine practice and clinical trials. The use of IMRT involves a learning curve for the practitioner and will continue to evolve, requiring continuing education and monitoring of outcomes from routine practice. Additional standards pertaining to a variety of issues, including target definitions and dose specification, need to be developed. Phase III trials will better define the role of IMRT in coming years.

Design and implementation of a head-and-neck phantom for system audit and verification of intensity-modulated radiation therapy.

PubMed

Webster, Gareth J; Hardy, Mark J; Rowbottom, Carl G; Mackay, Ranald I

2008-04-16

The head and neck is a challenging anatomic site for intensity-modulated radiation therapy (IMRT), requiring thorough testing of planning and treatment delivery systems. Ideally, the phantoms used should be anatomically realistic, have radiologic properties identical to those of the tissues concerned, and allow for the use of a variety of devices to verify dose and dose distribution in any target or normaltissue structure. A phantom that approaches the foregoing characteristics has been designed and built; its specific purpose is verification for IMRT treatments in the head-andneck region. This semi-anatomic phantom, HANK, is constructed of Perspex (Imperial Chemical Industries, London, U.K.) and provides for the insertion of heterogeneities simulating air cavities in a range of fixed positions. Chamber inserts are manufactured to incorporate either a standard thimble ionization chamber (0.125 cm3: PTW, Freiburg, Germany) or a smaller PinPoint chamber (0.015 cm3: PTW), and measurements can be made with either chamber in a range of positions throughout the phantom. Coronal films can also be acquired within the phantom, and additional solid blocks of Perspex allow for transverse films to be acquired within the head region. Initial studies using simple conventional head-and-neck plans established the reproducibility of the phantom and the measurement devices to within the setup uncertainty of +/- 0.5 mm. Subsequent verification of 9 clinical head-and-neck IMRT plans demonstrated the efficacy of the phantom in making a range of patient-specific dose measurements in regions of dosimetric and clinical interest. Agreement between measured values and those predicted by the Pinnacle3 treatment planning system (Philips Medical Systems, Andover, MA) was found to be generally good, with a mean error on the calculated dose to each point of +0.2% (range: -4.3% to +2.2%; n = 9) for the primary planning target volume (PTV), -0.1% (range: -1.5% to +2.0%; n = 8) for the nodal PTV, and +0.0% (range: -1.8% to +4.3%, n = 9) for the spinal cord. The suitability of the phantom for measuring combined dose distributions using radiographic film was also evaluated. The phantom has proved to be a valuable tool in the development and implementation of clinical head-and-neck IMRT, allowing for accurate verification of absolute dose and dose distributions in regions of clinical and dosimetric interest.

Comparison of intravascular ultrasound to contrast-enhanced 64-slice computed tomography to assess the significance of angiographically ambiguous coronary narrowings.

PubMed

Okabe, Teruo; Weigold, Wm Guy; Mintz, Gary S; Roswell, Robert; Joshi, Subodh; Lee, Sung Yun; Lee, Bongryeol; Steinberg, Daniel H; Roy, Probal; Slottow, Tina L Pinto; Smith, Kimberly; Torguson, Rebecca; Xue, Zhenyi; Satler, Lowell F; Kent, Kenneth M; Pichard, Augusto D; Weissman, Neil J; Lindsay, Joseph; Waksman, Ron

2008-10-15

The efficacy of contrast-enhanced multislice computed tomography (MSCT) for assessment of ambiguous lesions is unknown. We compared both quantitative coronary angiography (QCA) and MSCT to the gold standard for a significant stenosis-minimum luminal area (MLA) by intravascular ultrasound (IVUS)-in 51 patients (64 +/- 10 years old, 19 men) with 69 angiographically ambiguous, nonleft main lesions. The MSCT was performed 17 +/- 18 days before IVUS analysis. Overall diameter stenosis by QCAwas 51.0 +/- 9.8%; 39 of 51 patients (76%) eventually underwent revascularization (38 by percutaneous coronary intervention and 1 by coronary artery bypass graft). By univariate analysis, minimum luminal diameter, MLA, lumen visibility by MSCT, and minimum luminal diameter by QCA were significant predictors of MLA by IVUS

SU-E-T-368: Evaluating Dosimetric Outcome of Modulated Photon Radiotherapy (XMRT) Optimization for Head and Neck Patients

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

McGeachy, P; Villarreal-Barajas, JE; Khan, R

2015-06-15

Purpose: The dosimetric outcome of optimized treatment plans obtained by modulating the photon beamlet energy and fluence on a small cohort of four Head and Neck (H and N) patients was investigated. This novel optimization technique is denoted XMRT for modulated photon radiotherapy. The dosimetric plans from XMRT for H and N treatment were compared to conventional, 6 MV intensity modulated radiotherapy (IMRT) optimization plans. Methods: An arrangement of two non-coplanar and five coplanar beams was used for all four H and N patients. Both XMRT and IMRT were subject to the same optimization algorithm, with XMRT optimization allowing bothmore » 6 and 18 MV beamlets while IMRT was restricted to 6 MV only. The optimization algorithm was based on a linear programming approach with partial-volume constraints implemented via the conditional value-at-risk method. H and N constraints were based off of those mentioned in the Radiation Therapy Oncology Group 1016 protocol. XMRT and IMRT solutions were assessed using metrics suggested by International Commission on Radiation Units and Measurements report 83. The Gurobi solver was used in conjunction with the CVX package to solve each optimization problem. Dose calculations and analysis were done in CERR using Monte Carlo dose calculation with VMC{sub ++}. Results: Both XMRT and IMRT solutions met all clinical criteria. Trade-offs were observed between improved dose uniformity to the primary target volume (PTV1) and increased dose to some of the surrounding healthy organs for XMRT compared to IMRT. On average, IMRT improved dose to the contralateral parotid gland and spinal cord while XMRT improved dose to the brainstem and mandible. Conclusion: Bi-energy XMRT optimization for H and N patients provides benefits in terms of improved dose uniformity to the primary target and reduced dose to some healthy structures, at the expense of increased dose to other healthy structures when compared with IMRT.« less

Local control after intensity-modulated radiotherapy for head-and-neck rhabdomyosarcoma.

PubMed

Curtis, Amarinthia E; Okcu, M Fatih; Chintagumpala, Murali; Teh, Bin S; Paulino, Arnold C

2009-01-01

To examine the patterns of failure in patients treated with intensity-modulated radiotherapy (IMRT) for head-and-neck rhabdomyosarcoma (RMS). Between 1998 and 2005, 19 patients with a diagnosis of head-and-neck RMS received IMRT at The Methodist Hospital. There were 11 male and 8 female patients, with a median age of 6 years at time of irradiation. Tumor location was parameningeal in 7, orbital in 6, and other head-and-neck RMS in 6. Chemotherapy was given to all patients, with vincristine, actinomycin D, and cyclophosphamide being the most common regimen (n = 18). The median prescribed dose was 5040 cGy. The clinical target volume included the gross tumor volume with a 1.5-cm margin. The median duration of follow-up for surviving patients was 56 months. The 4-year overall survival and local control rates were 76% and 92.9%, respectively. One patient developed a local failure in the high-dose region of the radiation field; there were no marginal failures. Distant metastasis was seen in 4 patients. Overall survival was 42.9% for parameningeal sites and 100% for other sites (p < 0.01). Late toxicities were seen in 7 patients. Two secondary malignancies occurred in 1 child with embryonal RMS of the face and a p53 mutation. Local control was excellent in patients receiving IMRT for head-and-neck RMS. Patterns of local failure reveal no marginal failures in this group of patients.

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

Fury, Matthew G.; Department of Medicine, Weill Cornell Medical College, New York, New York; Lee, Nancy Y.

Purpose: Elevated expression of eukaryotic protein synthesis initiation factor 4E (eIF4E) in histologically cancer-free margins of resected head and neck squamous cell carcinomas (HNSCCs) is mediated by mammalian target of rapamycin complex 1 (mTORC1) and has been associated with increased risk of disease recurrence. Preclinically, inhibition of mTORC1 with everolimus sensitizes cancer cells to cisplatin and radiation. Methods and Materials: This was single-institution phase 1 study to establish the maximum tolerated dose of daily everolimus given with fixed dose cisplatin (30 mg/m{sup 2} weekly × 6) and concurrent intensity modulated radiation therapy for patients with locally and/or regionally advanced head-and-neckmore » cancer. The study had a standard 3 + 3 dose-escalation design. Results: Tumor primary sites were oral cavity (4), salivary gland (4), oropharynx (2), nasopharynx (1), scalp (1), and neck node with occult primary (1). In 4 of 4 cases in which resected HNSCC surgical pathology specimens were available for immunohistochemistry, elevated expression of eIF4E was observed in the cancer-free margins. The most common grade ≥3 treatment-related adverse event was lymphopenia (92%), and dose-limiting toxicities (DLTs) were mucositis (n=2) and failure to thrive (n=1). With a median follow up of 19.4 months, 2 patients have experienced recurrent disease. The maximum tolerated dose was everolimus 5 mg/day. Conclusions: Head-and-neck cancer patients tolerated everolimus at therapeutic doses (5 mg/day) given with weekly cisplatin and intensity modulated radiation therapy. The regimen merits further evaluation, especially among patients who are status post resection of HNSCCs that harbor mTORC1-mediated activation of eIF4E in histologically negative surgical margins.« less

Assessment of left atrial volume and function: a comparative study between echocardiography, magnetic resonance imaging and multi slice computed tomography.

PubMed

Kühl, J Tobias; Lønborg, Jacob; Fuchs, Andreas; Andersen, Mads J; Vejlstrup, Niels; Kelbæk, Henning; Engstrøm, Thomas; Møller, Jacob E; Kofoed, Klaus F

2012-06-01

Measurement of left atrial (LA) maximal volume (LA(max)) using two-dimensional transthoracic echocardiography (TTE) provides prognostic information in several cardiac diseases. However, the relationship between LA(max) and LA function is poorly understood and TTE is less well suited for measuring dynamic LA volume changes. Conversely, cardiac magnetic resonance imaging (CMR) and multi-slice computed tomography (MSCT) appears more appropriate for such measures. We sought to determine the relationship between LA size assessed with TTE and LA size and function assessed with CMR and MSCT. Fifty-four patients were examined 3 months post myocardial infarction with echocardiography, CMR and MSCT. Left atrial volumes and LA reservoir function were assessed by TTE. LA time-volume curves were determined and LA reservoir function (cyclic change and fractional change), passive emptying function (reservoir volume) and pump function (left atrial ejection fraction-LAEF) were derived using CMR and MSCT. Left atrial fractional change and left atrial ejection fraction (LAEF) determined with CMR and MSCT were unrelated to LA(max) enlargement by echocardiography (P = NS). There was an overall good agreement between CMR and MSCT, with a small to moderate bias in LA(max) (4.9 ± 10.4 ml), CC (3.1 ± 9.1 ml) and reservoir volume (3.4 ± 9.1 ml). TTE underestimates LA(max) with up to 32% compared with CMR and MSCT (P < 0.001). Left atrial function assessed with MSCT and CMR as LA fractional change and LAEF is not significantly related to LA(max) measured by TTE. TTE systematically underestimated LA volumes, whereas there are good agreements between MSCT and CMR for volumetric and functional properties.

Improved normal tissue sparing in head and neck radiotherapy using biological cost function based-IMRT.

PubMed

Anderson, N; Lawford, C; Khoo, V; Rolfo, M; Joon, D L; Wada, M

2011-12-01

Intensity-modulated radiotherapy (IMRT) has reduced the impact of acute and late toxicities associated with head and neck radiotherapy. Treatment planning system (TPS) advances in biological cost function based optimization (BBO) and improved segmentation techniques have increased organ at risk (OAR) sparing compared to conventional dose-based optimization (DBO). A planning study was undertaken to compare OAR avoidance in DBO and BBO treatment planning. Simultaneous integrated boost treatment plans were produced for 10 head and neck patients using both planning systems. Plans were compared for tar get coverage and OAR avoidance. Comparisons were made using the BBO TPS Monte Carlo dose engine to eliminate differences due to inherent algorithms. Target coverage (V95%) was maintained for both solutions. BBO produced lower OAR doses, with statistically significant improvement to left (12.3%, p = 0.005) and right parotid mean dose (16.9%, p = 0.004), larynx V50_Gy (71.0%, p = 0.005), spinal cord (21.9%, p < 0.001) and brain stem dose maximums (31.5%, p = 0.002). This study observed improved OAR avoidance with BBO planning. Further investigations will be undertaken to review any clinical benefit of this improved planned dosimetry.

Improved Normal Tissue Sparing in Head and Neck Radiotherapy Using Biological Cost Function Based-IMRT

PubMed Central

Anderson, N.; Lawford, C.; Khoo, V.; Rolfo, M.; Joon, D. Lim; Wada, M.

2011-01-01

Intensity-modulated radiotherapy (IMRT) has reduced the impact of acute and late toxicities associated with head and neck radiotherapy. Treatment planning system (TPS) advances in biological cost function based optimization (BBO) and improved segmentation techniques have increased organ at risk (OAR) sparing compared to conventional dose-based optimization (DBO). A planning study was undertaken to compare OAR avoidance in DBO and BBO treatment planning. Simultaneous integrated boost treatment plans were produced for 10 head and neck patients using both planning systems. Plans were compared for tar get coverage and OAR avoidance. Comparisons were made using the BBO TPS Monte Carlo dose engine to eliminate differences due to inherent algorithms. Target coverage (V95%) was maintained for both solutions. BBO produced lower OAR doses, with statistically significant improvement to left (12.3%, p = 0.005) and right parotid mean dose (16.9%, p = 0.004), larynx V50 Gy (71.0%, p = 0.005), spinal cord (21.9%, p < 0.001) and brain stem dose maximums (31.5%, p = 0.002). This study observed improved OAR avoidance with BBO planning. Further investigations will be undertaken to review any clinical benefit of this improved planned dosimetry. PMID:22066597

Hyperbaric Oxygen as Radiation Sensitizer for Locally Advanced Squamous Cell Carcinoma of the Oropharynx: A Phase 1 Dose-Escalation Study.

PubMed

Hartford, Alan C; Davis, Thomas H; Buckey, Jay C; Foote, Robert L; Sinesi, Mark S; Williams, Benjamin B; Fariss, Anna K; Schaner, Philip E; Claus, Paul L; Okuno, Scott H; Hussey, James R; Clarke, Richard E

2017-03-01

To explore, in a dose-escalation study, the feasibility of hyperbaric oxygen (HBO) treatments immediately before intensity modulated radiation therapy in conjunction with cisplatinum chemotherapy for squamous cell carcinoma of the head and neck (SCCHN). Eligible patients presented with SCCHN (stage III-IV [M0]), life expectancy >6 months, and Karnofsky performance status ≥70. Enrollees received intensity modulated radiation therapy, 70 Gy in 35 fractions over 7 weeks with weekly cisplatinum. Patients received HBO-100% oxygen, 2.4 atmospheres absolute (ATA) for 30 minutes-twice per week initially. Subsequent patients were escalated to 3 and then 5 times per week. Intensity modulated radiation therapy began within 15 minutes after HBO. Patients were followed for 2 years after RT with quality-of-life questionnaires (Performance Status Scale-Head and Neck Cancer and the Functional Assessment of Cancer Therapy-Head and Neck Cancer) and for 5+ years for local recurrence, distant metastases, disease-specific survival, and overall survival. Twelve subjects enrolled from 3 centers. Two withdrew during radiation therapy and 1 within 14 weeks after radiation therapy. The remaining 9 had primary oropharyngeal disease and were stage IVA (7) or IVB (2). No dose-limiting toxicities were observed with daily HBO. Two patients (22%) required pressure equalization tubes. The average time between HBO and radiation therapy was 8.5 minutes, with 2 of 231 administrations delivered beyond 15 minutes (0.5%). Per-protocol analysis showed a clinical complete response in 7 and a pathologic complete response without tumor in salvage neck dissections in 2. With minimum follow-up of 61 months, per-protocol 5-year overall survival was 100%, local recurrence 0%, and distant metastases 11%. Patient-reported outcomes for quality of life (Functional Assessment of Cancer Therapy-Head and Neck Cancer) were comparable to published results for chemoradiotherapy without HBO. While acknowledging the study's small size and early attrition of 3 patients, our in-depth review of the acquired data indicates the feasibility of combining HBO with chemoradiation. Copyright © 2016 Elsevier Inc. All rights reserved.

Benefit of particle therapy in re-irradiation of head and neck patients. Results of a multicentric in silico ROCOCO trial.

PubMed

Eekers, Daniëlle B P; Roelofs, Erik; Jelen, Urszula; Kirk, Maura; Granzier, Marlies; Ammazzalorso, Filippo; Ahn, Peter H; Janssens, Geert O R J; Hoebers, Frank J P; Friedmann, Tobias; Solberg, Timothy; Walsh, Sean; Troost, Esther G C; Kaanders, Johannes H A M; Lambin, Philippe

2016-12-01

In this multicentric in silico trial we compared photon, proton, and carbon-ion radiotherapy plans for re-irradiation of patients with squamous cell carcinoma of the head and neck (HNSCC) regarding dose to tumour and doses to surrounding organs at risk (OARs). Twenty-five HNSCC patients with a second new or recurrent cancer after previous irradiation (70Gy) were included. Intensity-modulated proton therapy (IMPT) and ion therapy (IMIT) re-irradiation plans to a second subsequent dose of 70Gy were compared to photon therapy delivered with volumetric modulated arc therapy (VMAT). When comparing IMIT and IMPT to VMAT, the mean dose to all investigated 22 OARs was significantly reduced for IMIT and to 15 out of 22 OARs (68%) using IMPT. The maximum dose to 2% volume (D 2 ) of the brainstem and spinal cord were significantly reduced using IMPT and IMIT compared to VMAT. The data are available on www.cancerdata.org. In this ROCOCO in silico trial, a reduction in mean dose to OARs was achieved using particle therapy compared to photons in the re-irradiation of HNSCC. There was a dosimetric benefit favouring carbon-ions above proton therapy. These dose reductions may potentially translate into lower severe complication rates related to the re-irradiation. Copyright © 2016 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

SU-F-T-186: A Treatment Planning Study of Normal Tissue Sparing with Robustness Optimized IMPT, 4Pi IMRT, and VMAT for Head and Neck Cases

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

Zhang, J; Li, X; Ding, X

Purpose: We performed a retrospective dosimetric comparison study between the robustness optimized Intensity Modulated Proton Therapy (RO-IMPT), volumetric-modulated arc therapy (VMAT), and the non-coplanar 4? intensity modulated radiation therapy (IMRT). These methods represent the most advanced radiation treatment methods clinically available. We compare their dosimetric performance for head and neck cancer treatments with special focus on the OAR sparing near the tumor volumes. Methods: A total of 11 head and neck cases, which include 10 recurrent cases and one bilateral case, were selected for the study. Different dose levels were prescribed to tumor target depending on disease and location. Threemore » treatment plans were created on commercial TPS systems for a novel noncoplanar 4π method (20 beams), VMAT, and RO-IMPT technique (maximum 4 fields). The maximum patient positioning error was set to 3 mm and the maximum proton range uncertainty was set to 3% for the robustness optimization. Line dose profiles were investigated for OARs close to tumor volumes. Results: All three techniques achieved 98% coverage of the CTV target and most photon plans had less than 110% of the hot spots. The RO-IMPT plans show superior tumor dose homogeneity than 4? and VMAT plans. Although RO-IMPT has greater R50 dose spillage to the surrounding normal tissue than 4π and VMAT, the RO-IMPT plans demonstrate better or comparable OAR (parotid, mandible, carotid, oral cavity, pharynx, and etc.) sparing for structures closely abutting tumor targets. Conclusion: The RO-IMPT’s ability of OAR sparing is benchmarked against the C-arm linac based non-coplanar 4π technique and the standard VMAT method. RO-IMPT consistently shows better or comparable OAR sparing even for tissue structures closely abutting treatment target volume. RO-IMPT further reduces treatment uncertainty associated with proton therapy and delivers robust treatment plans to both unilateral and bilateral head and neck cancer patients with desirable treatment time.« less

SU-E-T-109: An Investigation of Including Variable Relative Biological Effectiveness in Intensity Modulated Proton Therapy Planning Optimization for Head and Neck Cancer Patients

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

Cao, W; Zaghian, M; Lim, G

2015-06-15

Purpose: The current practice of considering the relative biological effectiveness (RBE) of protons in intensity modulated proton therapy (IMPT) planning is to use a generic RBE value of 1.1. However, RBE is indeed a variable depending on the dose per fraction, the linear energy transfer, tissue parameters, etc. In this study, we investigate the impact of using variable RBE based optimization (vRBE-OPT) on IMPT dose distributions compared by conventional fixed RBE based optimization (fRBE-OPT). Methods: Proton plans of three head and neck cancer patients were included for our study. In order to calculate variable RBE, tissue specific parameters were obtainedmore » from the literature and dose averaged LET values were calculated by Monte Carlo simulations. Biological effects were calculated using the linear quadratic model and they were utilized in the variable RBE based optimization. We used a Polak-Ribiere conjugate gradient algorithm to solve the model. In fixed RBE based optimization, we used conventional physical dose optimization to optimize doses weighted by 1.1. IMPT plans for each patient were optimized by both methods (vRBE-OPT and fRBE-OPT). Both variable and fixed RBE weighted dose distributions were calculated for both methods and compared by dosimetric measures. Results: The variable RBE weighted dose distributions were more homogenous within the targets, compared with the fixed RBE weighted dose distributions for the plans created by vRBE-OPT. We observed that there were noticeable deviations between variable and fixed RBE weighted dose distributions if the plan were optimized by fRBE-OPT. For organs at risk sparing, dose distributions from both methods were comparable. Conclusion: Biological dose based optimization rather than conventional physical dose based optimization in IMPT planning may bring benefit in improved tumor control when evaluating biologically equivalent dose, without sacrificing OAR sparing, for head and neck cancer patients. The research is supported in part by National Institutes of Health Grant No. 2U19CA021239-35.« less

Automatic exposure control in CT: the effect of patient size, anatomical region and prescribed modulation strength on tube current and image quality.

PubMed

Papadakis, Antonios E; Perisinakis, Kostas; Damilakis, John

2014-10-01

To study the effect of patient size, body region and modulation strength on tube current and image quality on CT examinations that use automatic tube current modulation (ATCM). Ten physical anthropomorphic phantoms that simulate an individual as neonate, 1-, 5-, 10-year-old and adult at various body habitus were employed. CT acquisition of head, neck, thorax and abdomen/pelvis was performed with ATCM activated at weak, average and strong modulation strength. The mean modulated mAs (mAsmod) values were recorded. Image noise was measured at selected anatomical sites. The mAsmod recorded for neonate compared to 10-year-old increased by 30 %, 14 %, 6 % and 53 % for head, neck, thorax and abdomen/pelvis, respectively, (P < 0.05). The mAsmod was lower than the preselected mAs with the exception of the 10-year-old phantom. In paediatric and adult phantoms, the mAsmod ranged from 44 and 53 for weak to 117 and 93 for strong modulation strength, respectively. At the same exposure parameters image noise increased with body size (P < 0.05). The ATCM system studied here may affect dose differently for different patient habitus. Dose may decrease for overweight adults but increase for children older than 5 years old. Care should be taken when implementing ATCM protocols to ensure that image quality is maintained. • ATCM efficiency is related to the size of the patient's body. • ATCM should be activated without caution in overweight adult individuals. • ATCM may increase radiation dose in children older than 5 years old. • ATCM efficiency depends on the protocol selected for a specific anatomical region. • Modulation strength may be appropriately tuned to enhance ATCM efficiency.

Energy modulated electron therapy using a few leaf electron collimator in combination with IMRT and 3D-CRT: Monte Carlo-based planning and dosimetric evaluation

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

Al-Yahya, Khalid; Schwartz, Matthew; Shenouda, George

2005-09-15

Energy modulated electron therapy (EMET) based on Monte Carlo dose calculation is a promising technique that enhances the treatment planning and delivery of superficially located tumors. This study investigated the application of EMET using a novel few-leaf electron collimator (FLEC) in head and neck and breast sites in comparison with three-dimensional conventional radiation therapy (3D-CRT) and intensity modulated radiation therapy (IMRT) techniques. Treatment planning was performed for two parotid cases and one breast case. Four plans were compared for each case: 3D-CRT, IMRT, 3D-CRT in conjunction with EMET (EMET-CRT), and IMRT in conjunction with EMET (EMET-IMRT), all of which weremore » performed and calculated with Monte Carlo techniques. For all patients, dose volume histograms (DVHs) were obtained for all organs of interest and the DVHs were used as a means of comparing the plans. Homogeneity and conformity of dose distributions were calculated, as well as a sparing index that compares the effect of the low isodose lines. In addition, the whole-body dose equivalent (WBDE) was estimated for each plan. Adding EMET delivered with the FLEC to 3D-CRT improves sparing of normal tissues. For the two head and neck cases, the mean dose to the contralateral parotid and brain stem was reduced relative to IMRT by 43% and 84%, and by 57% and 71%, respectively. Improved normal tissue sparing was quantified as an increase in sparing index of 47% and 30% for the head and neck and the breast cases, respectively. Adding EMET to either 3D-CRT or IMRT results in preservation of target conformity and dose homogeneity. When adding EMET to the treatment plan, the WBDE was reduced by between 6% and 19% for 3D-CRT and by between 21% and 33% for IMRT, while WBDE for EMET-CRT was reduced by up to 72% when compared with IMRT. FLEC offers a practical means of delivering modulated electron therapy. Although adding EMET delivered using the FLEC results in perturbation of target conformity when compared to IMRT, it significantly improves normal tissue sparing while offering enhanced target conformity to the 3D-CRT planning. The addition of EMET systematically leads to a reduction in WBDE especially when compared with IMRT.« less

Complete genome of the cotton bacteria blight pathogen Xanthomonas citri pv. malvacearum strain MSCT

USDA-ARS?s Scientific Manuscript database

Xanthomonas citri pv. malvacearum (Xcm) is a major pathogen of Gossypium hirsutum. In this study we report the complete genome of the Xcm strain MSCT assembled from long read DNA sequencing technology. The MSCT genome is the first Xcm genome that has complete coding regions for Xcm transcriptional a...

Reliability of voxel gray values in cone beam computed tomography for preoperative implant planning assessment.

PubMed

Parsa, Azin; Ibrahim, Norliza; Hassan, Bassam; Motroni, Alessandro; van der Stelt, Paul; Wismeijer, Daniel

2012-01-01

To assess the reliability of cone beam computed tomography (CBCT) voxel gray value measurements using Hounsfield units (HU) derived from multislice computed tomography (MSCT) as a clinical reference (gold standard). Ten partially edentulous human mandibular cadavers were scanned by two types of computed tomography (CT) modalities: multislice CT and cone beam CT. On MSCT scans, eight regions of interest (ROI) designating the site for preoperative implant placement were selected in each mandible. The datasets from both CT systems were matched using a three-dimensional (3D) registration algorithm. The mean voxel gray values of the region around the implant sites were compared between MSCT and CBCT. Significant differences between the mean gray values obtained by CBCT and HU by MSCT were found. In all the selected ROIs, CBCT showed higher mean values than MSCT. A strong correlation (R=0.968) between mean voxel gray values of CBCT and mean HU of MSCT was determined. Voxel gray values from CBCT deviate from actual HU units. However, a strong linear correlation exists, which may permit deriving actual HU units from CBCT using linear regression models.

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

SU-F-T-449: Dosimetric Comparison of Acuros XB, Adaptive Convolve in Intensity Modulated Radiotherapy for Head and Neck Cancer

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

Uehara, R; Tachibana, H

Purpose: There have been several publications focusing on dose calculation in lung for a new dose calculation algorithm of Acuros XB (AXB). AXB could contribute to dose calculation for high-density media for bone and dental prosthesis rather than in lung. We compared the dosimetric performance of AXB, Adaptive Convolve (AC) in head and neck IMRT plans. Methods: In a phantom study, the difference in depth profile between AXB and AC was evaluated using Kodak EDR2 film sandwiched with tough water phantoms. 6 MV x-ray using the TrueBeam was irradiated. In a patient study, 20 head and neck IMRT plans hadmore » been clinically approved in Pinnacle3 and were transferred to Eclipse. Dose distribution was recalculated using AXB in Eclipse while maintaining AC-calculated monitor units and MLC sequence planned in Pinnacle. Subsequently, both the dose-volumetric data obtained using the two different calculation algorithms were compared. Results: The results in the phantom evaluation for the shallow area ahead of the build-up region shows over-dose for AXB and under-dose for AC, respectively. In the patient plans, AXB shows more hot spots especially around the high-density media than AC in terms of PTV (Max difference: 4.0%) and OAR (Max. difference: 1.9%). Compared to AC, there were larger dose deviations in steep dose gradient region and higher skin-dose. Conclusion: In head and neck IMRT plans, AXB and AC show different dosimetric performance for the regions inside the target volume around high-density media, steep dose gradient regions and skin-surface. There are limitations in skin-dose and complex anatomic condition using even inhomogeneous anthropomorphic phantom Thus, there is the potential for an increase of hot-spot in AXB, and an underestimation of dose in substance boundaries and skin regions in AC.« less

Multislice spiral computed tomography for the evaluation of stent patency after left main coronary artery stenting: a comparison with conventional coronary angiography and intravascular ultrasound.

PubMed

Van Mieghem, Carlos A G; Cademartiri, Filippo; Mollet, Nico R; Malagutti, Patrizia; Valgimigli, Marco; Meijboom, Willem B; Pugliese, Francesca; McFadden, Eugene P; Ligthart, Jurgen; Runza, Giuseppe; Bruining, Nico; Smits, Pieter C; Regar, Evelyn; van der Giessen, Willem J; Sianos, Georgios; van Domburg, Ron; de Jaegere, Peter; Krestin, Gabriel P; Serruys, Patrick W; de Feyter, Pim J

2006-08-15

Surveillance conventional coronary angiography (CCA) is recommended 2 to 6 months after stent-supported left main coronary artery (LMCA) percutaneous coronary intervention due to the unpredictable occurrence of in-stent restenosis (ISR), with its attendant risks. Multislice computed tomography (MSCT) is a promising technique for noninvasive coronary evaluation. We evaluated the diagnostic performance of high-resolution MSCT to detect ISR after stenting of the LMCA. Seventy-four patients were prospectively identified from a consecutive patient population scheduled for follow-up CCA after LMCA stenting and underwent MSCT before CCA. Until August 2004, a 16-slice scanner was used (n = 27), but we switched to the 64-slice scanner after that period (n = 43). Patients with initial heart rates > 65 bpm received beta-blockers, which resulted in a mean periscan heart rate of 57 +/- 7 bpm. Among patients with technically adequate scans (n = 70), MSCT correctly identified all patients with ISR (10 of 70) but misclassified 5 patients without ISR (false-positives). Overall, the accuracy of MSCT for detection of angiographic ISR was 93%. The sensitivity, specificity, and positive and negative predictive values were 100%, 91%, 67%, and 100%, respectively. When analysis was restricted to patients with stenting of the LMCA with or without extension into a single major side branch, accuracy was 98%. When both branches of the LMCA bifurcation were stented, accuracy was 83%. For the assessment of stent diameter and area, MSCT showed good correlation with intravascular ultrasound (r = 0.78 and 0.73, respectively). An intravascular ultrasound threshold value > or = 1 mm was identified to reliably detect in-stent neointima hyperplasia with MSCT. Current MSCT technology, in combination with optimal heart rate control, allows reliable noninvasive evaluation of selected patients after LMCA stenting. MSCT is safe to exclude left main ISR and may therefore be an acceptable first-line alternative to CCA.

Accuracy of MSCT Coronary Angiography with 64 Row CT Scanner—Facing the Facts

PubMed Central

Wehrschuetz, M.; Wehrschuetz, E.; Schuchlenz, H.; Schaffler, G.

2010-01-01

Improvements in multislice computed tomography (MSCT) angiography of the coronary vessels have enabled the minimally invasive detection of coronary artery stenoses, while quantitative coronary angiography (QCA) is the accepted reference standard for evaluation thereof. Sixteen-slice MSCT showed promising diagnostic accuracy in detecting coronary artery stenoses haemodynamically and the subsequent introduction of 64-slice scanners promised excellent and fast results for coronary artery studies. This prompted us to evaluate the diagnostic accuracy, sensitivity, specificity, and the negative und positive predictive value of 64-slice MSCT in the detection of haemodynamically significant coronary artery stenoses. Thirty-seven consecutive subjects with suspected coronary artery disease were evaluated with MSCT angiography and the results compared with QCA. All vessels were considered for the assessment of significant coronary artery stenosis (diameter reduction ≥ 50%). Thirteen patients (35%) were identified as having significant coronary artery stenoses on QCA with 6.3% (35/555) affected segments. None of the coronary segments were excluded from analysis. Overall sensitivity for classifying stenoses of 64-slice MSCT was 69%, specificity was 92%, positive predictive value was 38% and negative predictive value was 98%. The interobserver variability for detection of significant lesions had a k-value of 0.43. Sixty-four-slice MSCT offers the diagnostic potential to detect coronary artery disease, to quantify haemodynamically significant coronary artery stenoses and to avoid unnecessary invasive coronary artery examinations. PMID:20567636

Lack of Osteoradionecrosis of the Mandible After Intensity-Modulated Radiotherapy for Head and Neck Cancer: Likely Contributions of Both Dental Care and Improved Dose Distributions

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

Ben-David, Merav A.; Diamante, Maximiliano; Radawski, Jeffrey D.

Purpose: To assess the prevalence and dosimetric and clinical predictors of mandibular osteoradionecrosis (ORN) in patients with head and neck cancer who underwent a pretherapy dental evaluation and prophylactic treatment according to a uniform policy and were treated with intensity-modulated radiotherapy (IMRT). Methods and Materials: Between 1996 and 2005, all patients with head-and-neck cancer treated with parotid gland-sparing IMRT in prospective studies underwent a dental examination and prophylactic treatment according to a uniform policy that included extractions of high-risk, periodontally involved, and nonrestorable teeth in parts of the mandible expected to receive high radiation doses, fluoride supplements, and the placementmore » of guards aiming to reduce electron backscatter off metal teeth restorations. The IMRT plans included dose constraints for the maximal mandibular doses and reduced mean parotid gland and noninvolved oral cavity doses. A retrospective analysis of Grade 2 or worse (clinical) ORN was performed. Results: A total of 176 patients had a minimal follow-up of 6 months. Of these, 31 (17%) had undergone teeth extractions before RT and 13 (7%) after RT. Of the 176 patients, 75% and 50% had received {>=}65 Gy and {>=}70 Gy to {>=}1% of the mandibular volume, respectively. Falloff across the mandible characterized the dose distributions: the average gradient (in the axial plane containing the maximal mandibular dose) was 11 Gy (range, 1-27 Gy; median, 8 Gy). At a median follow-up of 34 months, no cases of ORN had developed (95% confidence interval, 0-2%). Conclusion: The use of a strict prophylactic dental care policy and IMRT resulted in no case of clinical ORN. In addition to the dosimetric advantages offered by IMRT, meticulous dental prophylactic care is likely an essential factor in reducing ORN risk.« less

The Impact of Monte Carlo Dose Calculations on Intensity-Modulated Radiation Therapy

NASA Astrophysics Data System (ADS)

Siebers, J. V.; Keall, P. J.; Mohan, R.

The effect of dose calculation accuracy for IMRT was studied by comparing different dose calculation algorithms. A head and neck IMRT plan was optimized using a superposition dose calculation algorithm. Dose was re-computed for the optimized plan using both Monte Carlo and pencil beam dose calculation algorithms to generate patient and phantom dose distributions. Tumor control probabilities (TCP) and normal tissue complication probabilities (NTCP) were computed to estimate the plan outcome. For the treatment plan studied, Monte Carlo best reproduces phantom dose measurements, the TCP was slightly lower than the superposition and pencil beam results, and the NTCP values differed little.

In vivo dose verification of IMRT treated head and neck cancer patients.

PubMed

Engström, Per E; Haraldsson, Pia; Landberg, Torsten; Sand Hansen, Hanne; Aage Engelholm, Svend; Nyström, Håkan

2005-01-01

An independent in vivo dose verification procedure for IMRT treatments of head and neck cancers was developed. Results of 177 intracavitary TLD measurements from 10 patients are presented. The study includes data from 10 patients with cancer of the rhinopharynx or the thyroid treated with dynamic IMRT. Dose verification was performed by insertion of a flexible naso-oesophageal tube containing TLD rods and markers for EPID and simulator image detection. Part of the study focussed on investigating the accuracy of the TPS calculations in the presence of inhomogeneities. Phantom measurements and Monte Carlo simulations were performed for a number of geometries involving lateral electronic disequilibrium and steep density shifts. The in vivo TLD measurements correlated well with the predictions of the treatment planning system with a measured/calculated dose ratio of 1.002+/-0.051 (1 SD, N=177). The measurements were easily performed and well tolerated by the patients. We conclude that in vivo intracavitary dosimetry with TLD is suitable and accurate for dose determination in intensity-modulated beams.

Assessment of global and regional left ventricular function using 64-slice multislice computed tomography and 2D echocardiography: a comparison with cardiac magnetic resonance.

PubMed

Annuar, Bin Rapaee; Liew, Chee Khoon; Chin, Sze Piaw; Ong, Tiong Kiam; Seyfarth, M Tobias; Chan, Wei Ling; Fong, Yean Yip; Ang, Choon Kiat; Lin, Naing; Liew, Houng Bang; Sim, Kui Hian

2008-01-01

To compare the assessment of global and regional left ventricular (LV) function using 64-slice multislice computed tomography (MSCT), 2D echocardiography (2DE) and cardiac magnetic resonance (CMR). Thirty-two consecutive patients (mean age, 56.5+/-9.7 years) referred for evaluation of coronary artery using 64-slice MSCT also underwent 2DE and CMR within 48h. The global left ventricular function which include left ventricular ejection fraction (LVEF), left ventricular end diastolic volume (LVdV) and left ventricular end systolic volume (LVsV) were determine using the three modalities. Regional wall motion (RWM) was assessed visually in all three modalities. The CMR served as the gold standard for the comparison between 64-slice MSCT with CMR and 2DE with CMR. Statistical analysis included Pearson correlation coefficient, Bland-Altman plots and kappa-statistics. The 64-slice MSCT agreed well with CMR for assessment of LVEF (r=0.92; p<0.0001), LVdV (r=0.98; p<0.0001) and LVsV (r=0.98; p<0.0001). In comparison with 64-slice MSCT, 2DE showed moderate correlation with CMR for the assessment of LVEF (r=0.84; p<0.0001), LVdV (r=0.83; p<0.0001) and LVsV (r=0.80; p<0.0001). However in RWM analysis, 2DE showed better accuracy than 64-slice MSCT (94.3% versus 82.4%) and closer agreement (kappa=0.89 versus 0.63) with CMR. 64-Slice MSCT correlates strongly with CMR in global LV function however in regional LV function 2DE showed better agreement with CMR than 64-slice MSCT.

The potential of intensity-modulated proton radiotherapy to reduce swallowing dysfunction in the treatment of head and neck cancer: A planning comparative study.

PubMed

van der Laan, Hans Paul; van de Water, Tara A; van Herpt, Heleen E; Christianen, Miranda E M C; Bijl, Hendrik P; Korevaar, Erik W; Rasch, Coen R; van 't Veld, Aart A; van der Schaaf, Arjen; Schilstra, Cornelis; Langendijk, Johannes A

2013-04-01

Predictive models for swallowing dysfunction were developed previously and showed the potential of improved intensity-modulated radiotherapy to reduce the risk of swallowing dysfunction. Still the risk is high. The aim of this study was to determine the potential of swallowing-sparing (SW) intensity-modulated proton therapy (IMPT) in head and neck cancer (HNC) for reducing the risk of swallowing dysfunction relative to currently used photon therapy. Twenty-five patients with oropharyngeal (n = 21) and hypopharyngeal (n = 4) cancer received primary radiotherapy, including bilateral neck irradiation, using standard (ST) intensity-modulated photon therapy (IMRT). Prophylactic (54 Gy) and therapeutic (70 Gy) target volumes were defined. The dose to the parotid and submandibular glands was reduced as much as possible. Four additional radiotherapy plans were created for each patient: SW-IMRT, ST-IMPT, 3-beam SW-IMPT (3B-SW-IMPT) and 7-beam SW-IMPT (7B-SW-IMPT). All plans were optimized similarly, with additional attempts to spare the swallowing organs at risk (SWOARs) in the SW plans. Probabilities of swallowing dysfunction were calculated with recently developed predictive models. All plans complied with standard HNC radiotherapy objectives. The mean parotid gland doses were similar for the ST and SW photon plans, but clearly lower in all IMPT plans (ipsilateral parotid gland ST-IMRT: 46 Gy, 7B-SW-IMPT: 29 Gy). The mean dose in the SWOARs was lowest with SW-IMPT, in particular with 7B-SW-IMPT (supraglottic larynx ST-IMRT: 60 Gy, 7B-SW-IMPT: 40 Gy). The observed dose reductions to the SWOARs translated into substantial overall reductions in normal tissue complication risks for different swallowing dysfunction endpoints. Compared with ST-IMRT, the risk of physician-rated grade 2-4 swallowing dysfunction was reduced on average by 8.8% (95% CI 6.5-11.1%) with SW-IMRT, and by 17.2% (95% CI: 12.7-21.7%) with 7B-SW-IMPT. SWOAR-sparing with proton therapy has the potential to substantially reduce the risk of swallowing dysfunction compared to similar treatment with photons.

Comparison of Monte Carlo and analytical dose computations for intensity modulated proton therapy

NASA Astrophysics Data System (ADS)

Yepes, Pablo; Adair, Antony; Grosshans, David; Mirkovic, Dragan; Poenisch, Falk; Titt, Uwe; Wang, Qianxia; Mohan, Radhe

2018-02-01

To evaluate the effect of approximations in clinical analytical calculations performed by a treatment planning system (TPS) on dosimetric indices in intensity modulated proton therapy. TPS calculated dose distributions were compared with dose distributions as estimated by Monte Carlo (MC) simulations, calculated with the fast dose calculator (FDC) a system previously benchmarked to full MC. This study analyzed a total of 525 patients for four treatment sites (brain, head-and-neck, thorax and prostate). Dosimetric indices (D02, D05, D20, D50, D95, D98, EUD and Mean Dose) and a gamma-index analysis were utilized to evaluate the differences. The gamma-index passing rates for a 3%/3 mm criterion for voxels with a dose larger than 10% of the maximum dose had a median larger than 98% for all sites. The median difference for all dosimetric indices for target volumes was less than 2% for all cases. However, differences for target volumes as large as 10% were found for 2% of the thoracic patients. For organs at risk (OARs), the median absolute dose difference was smaller than 2 Gy for all indices and cohorts. However, absolute dose differences as large as 10 Gy were found for some small volume organs in brain and head-and-neck patients. This analysis concludes that for a fraction of the patients studied, TPS may overestimate the dose in the target by as much as 10%, while for some OARs the dose could be underestimated by as much as 10 Gy. Monte Carlo dose calculations may be needed to ensure more accurate dose computations to improve target coverage and sparing of OARs in proton therapy.

A quantitative assessment of volumetric and anatomic changes of the parotid gland during intensity-modulated radiotherapy for head and neck cancer using serial computed tomography

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

Ajani, Abdallah A.; Qureshi, Muhammad M.; Kovalchuk, Nataliya

To evaluate the change in volume and movement of the parotid gland measured by serial contrast-enhanced computed tomography scans in patients with head and neck cancer treated with parotid-sparing intensity-modulated radiotherapy (IMRT). A prospective study was performed on 13 patients with head and neck cancer undergoing dose-painted IMRT to 69.96 Gy in 33 fractions. Serial computed tomography scans were performed at baseline, weeks 2, 4, and 6 of radiotherapy (RT), and at 6 weeks post-RT. The parotid volume was contoured at each scan, and the movement of the medial and lateral borders was measured. The patient's body weight was recordedmore » at each corresponding week during RT. Regression analyses were performed to ascertain the rate of change during treatment as a percent change per fraction in parotid volume and distance relative to baseline. The mean parotid volume decreased by 37.3% from baseline to week 6 of RT. The overall rate of change in parotid volume during RT was−1.30% per fraction (−1.67% and−0.91% per fraction in≥31 Gy and<31 Gy mean planned parotid dose groups, respectively, p = 0.0004). The movement of parotid borders was greater in the≥31 Gy mean parotid dose group compared with the<31 Gy group (0.22% per fraction and 0.14% per fraction for the lateral border and 0.19% per fraction and 0.06% per fraction for the medial border, respectively). The median change in body weight was−7.4% (range, 0.75% to−17.5%) during RT. A positive correlation was noted between change in body weight and parotid volume during the course of RT (Spearman correlation coefficient, r = 0.66, p<0.01). Head and neck IMRT results in a volume loss of the parotid gland, which is related to the planned parotid dose, and the patient's weight loss during RT.« less

An automated dose tracking system for adaptive radiation therapy.

PubMed

Liu, Chang; Kim, Jinkoo; Kumarasiri, Akila; Mayyas, Essa; Brown, Stephen L; Wen, Ning; Siddiqui, Farzan; Chetty, Indrin J

2018-02-01

The implementation of adaptive radiation therapy (ART) into routine clinical practice is technically challenging and requires significant resources to perform and validate each process step. The objective of this report is to identify the key components of ART, to illustrate how a specific automated procedure improves efficiency, and to facilitate the routine clinical application of ART. Data was used from patient images, exported from a clinical database and converted to an intermediate format for point-wise dose tracking and accumulation. The process was automated using in-house developed software containing three modularized components: an ART engine, user interactive tools, and integration tools. The ART engine conducts computing tasks using the following modules: data importing, image pre-processing, dose mapping, dose accumulation, and reporting. In addition, custom graphical user interfaces (GUIs) were developed to allow user interaction with select processes such as deformable image registration (DIR). A commercial scripting application programming interface was used to incorporate automated dose calculation for application in routine treatment planning. Each module was considered an independent program, written in C++or C#, running in a distributed Windows environment, scheduled and monitored by integration tools. The automated tracking system was retrospectively evaluated for 20 patients with prostate cancer and 96 patients with head and neck cancer, under institutional review board (IRB) approval. In addition, the system was evaluated prospectively using 4 patients with head and neck cancer. Altogether 780 prostate dose fractions and 2586 head and neck cancer dose fractions went processed, including DIR and dose mapping. On average, daily cumulative dose was computed in 3 h and the manual work was limited to 13 min per case with approximately 10% of cases requiring an additional 10 min for image registration refinement. An efficient and convenient dose tracking system for ART in the clinical setting is presented. The software and automated processes were rigorously evaluated and validated using patient image datasets. Automation of the various procedures has improved efficiency significantly, allowing for the routine clinical application of ART for improving radiation therapy effectiveness. Copyright © 2017 Elsevier B.V. All rights reserved.

Marvin: an anatomical phantom for dosimetric evaluation of complex radiotherapy of the head and neck.

PubMed

Aitkenhead, A H; Rowbottom, C G; Mackay, R I

2013-10-07

We report on the design of Marvin, a Model Anatomy for Radiotherapy Verification and audit In the head and Neck and present results demonstrating its use in the development of the Elekta volumetric modulated arc therapy (VMAT) technique at the Christie, and in the audit of TomoTherapy and Varian RapidArc at other institutions. The geometry of Marvin was generated from CT datasets of eight male and female patients lying in the treatment position, with removable inhomogeneities modelling the sinuses and mandible. A modular system allows the phantom to be used with a range of detectors, with the locations of the modules being based on an analysis of a range of typical treatment plans (27 in total) which were mapped onto the phantom geometry. Results demonstrate the use of Gafchromic EBT2/EBT3 film for measurement of relative dose in a plane through the target and organs-at-risk, and the use of a small-volume ionization chamber for measurement of absolute dose in the target and spinal cord. Measurements made during the development of the head and neck VMAT protocol at the Christie quantified the improvement in plan delivery resulting from the installation of the Elekta Integrity upgrade (which permits an effectively continuously variable dose rate), with plans delivered before and after the upgrade having 88.5 ± 9.4% and 98.0 ± 2.2% respectively of points passing a gamma analysis (at 4%, 4 mm, global). Audits of TomoTherapy and Varian RapidArc neck techniques at other institutions showed a similar quality of plan delivery as for post-Integrity Elekta VMAT: film measurements for both techniques had >99% of points passing a gamma analysis at the clinical criteria of 4%, 4 mm, global, and >95% of points passing at tighter criteria of 3%, 3 mm, global; and absolute dose measurements in the PTV and spinal cord were within 1.5% and 3.5% of the planned doses respectively for both techniques. The results demonstrate that Marvin is an efficient and effective means of assessing the quality of delivery of complex radiotherapy in the head and neck, and is a useful tool to assist development and audit of these techniques.

Marvin: an anatomical phantom for dosimetric evaluation of complex radiotherapy of the head and neck

NASA Astrophysics Data System (ADS)

Aitkenhead, A. H.; Rowbottom, C. G.; Mackay, R. I.

2013-10-01

We report on the design of Marvin, a Model Anatomy for Radiotherapy Verification and audit In the head and Neck and present results demonstrating its use in the development of the Elekta volumetric modulated arc therapy (VMAT) technique at the Christie, and in the audit of TomoTherapy and Varian RapidArc at other institutions. The geometry of Marvin was generated from CT datasets of eight male and female patients lying in the treatment position, with removable inhomogeneities modelling the sinuses and mandible. A modular system allows the phantom to be used with a range of detectors, with the locations of the modules being based on an analysis of a range of typical treatment plans (27 in total) which were mapped onto the phantom geometry. Results demonstrate the use of Gafchromic EBT2/EBT3 film for measurement of relative dose in a plane through the target and organs-at-risk, and the use of a small-volume ionization chamber for measurement of absolute dose in the target and spinal cord. Measurements made during the development of the head and neck VMAT protocol at the Christie quantified the improvement in plan delivery resulting from the installation of the Elekta Integrity upgrade (which permits an effectively continuously variable dose rate), with plans delivered before and after the upgrade having 88.5 ± 9.4% and 98.0 ± 2.2% respectively of points passing a gamma analysis (at 4%, 4 mm, global). Audits of TomoTherapy and Varian RapidArc neck techniques at other institutions showed a similar quality of plan delivery as for post-Integrity Elekta VMAT: film measurements for both techniques had >99% of points passing a gamma analysis at the clinical criteria of 4%, 4 mm, global, and >95% of points passing at tighter criteria of 3%, 3 mm, global; and absolute dose measurements in the PTV and spinal cord were within 1.5% and 3.5% of the planned doses respectively for both techniques. The results demonstrate that Marvin is an efficient and effective means of assessing the quality of delivery of complex radiotherapy in the head and neck, and is a useful tool to assist development and audit of these techniques.

Anti-cancer effects of curcumin on head and neck cancers.

PubMed

Gao, Wei; Chan, Jimmy Yu-Wai; Wei, William Ignance; Wong, Thian-Sze

2012-11-01

Head and neck cancer is the sixth large type of cancer in the world. The treatment regimens for head and neck cancer encompass surgery, radiotherapy and chemotherapy. However, all current treatment regimens for head and neck cancer have adverse effects. Therefore, continuing investigations have been undertaken to seek less toxic therapies to reduce treatment morbidity for head and neck cancer. Substantial evidence has demonstrated that curcumin inhibited proliferation, migration, invasion and metastasis and induced apoptosis via modulating multiple signaling pathways in head and neck cancer. Curcumin also suppressed the growth of xenograft derived from head and neck cancer in vivo in animal models. This review summarizes the evidence demonstrating potential use of curcumin as a single chemotherapeutic agent or in combination with other chemotherapeutic agents and radiation to minimize their toxicity in head and neck cancer. Although curcumin has been shown to be safe at doses of 8 g/d in both phase I and phase II clinical trials, its bioavailability is poor. Overcoming the poor bioavailability of curcumin in the near future would facilitate its clinical use.

Hypothyroidism as a Consequence of Intensity-Modulated Radiotherapy With Concurrent Taxane-Based Chemotherapy for Locally Advanced Head-and-Neck Cancer

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

Diaz, Roberto; Jaboin, Jerry J.; Morales-Paliza, Manuel

Purpose: To conduct a retrospective review of 168 consecutively treated locally advanced head-and-neck cancer (LAHNC) patients treated with intensity-modulated radiotherapy (IMRT)/chemotherapy, to determine the rate and risk factors for developing hypothyroidism. Methods and Materials: Intensity-modulated radiotherapy was delivered in 33 daily fractions to 69.3 Gy to gross disease and 56.1 Gy to clinically normal cervical nodes. Dose-volume histograms (DVHs) of IMRT plans were used to determine radiation dose to thyroid and were compared with DVHs using conventional three-dimensional radiotherapy (3D-RT) in 10 of these same patients randomly selected for replanning and with DVHs of 16 patients in whom the thyroidmore » was intentionally avoided during IMRT. Weekly paclitaxel (30 mg/m{sup 2}) and carboplatin area under the curve-1 were given concurrently with IMRT. Results: Sixty-one of 128 evaluable patients (47.7%) developed hypothyroidism after a median of 1.08 years after IMRT (range, 2.4 months to 3.9 years). Age and volume of irradiated thyroid were associated with hypothyroidism development after IMRT. Compared with 3D-RT, IMRT with no thyroid dose constraints resulted in significantly higher minimum, maximum, and median dose (p < 0.0001) and percentage thyroid volume receiving 10, 20, and 60 Gy (p < 0.05). Compared with 3D-RT, IMRT with thyroid dose constraints resulted in lower median dose and percentage thyroid volume receiving 30, 40, and 50 Gy (p < 0.005) but higher minimum and maximum dose (p < 0.005). Conclusions: If not protected, IMRT for LAHNC can result in higher radiation to the thyroid than with conventional 3D-RT. Techniques to reduce dose and volume of radiation to thyroid tissue with IMRT are achievable and recommended.« less

SU-E-I-31: Differences Observed in Radiation Doses Across 2 Similar CT Scanners From Adult Brain-Neck CT Angiography

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

Fujii, K; UCLA School of Medicine, Los Angeles, CA; McMillan, K

2015-06-15

Purpose: The aim of this study is to evaluate the difference in radiation doses from adult Brain-Neck CT angiography (CTA) between two CT scanners. Methods: We collected CT dose index data (CTDIvol, DLP) from adult Brain-Neck CTA performed with two CT scanners (Sensation 64 (S64) and Definition AS (AS), Siemens Healthcare) performed at two of our facilities from Jan 1st to Dec 31th, 2014. X-ray dose management software (Radmetrics, Bayer Healthcare) was used to mine these data. All exams were performed with Tube Current Modulation (Care Dose 4D), tube voltage of 120 kVp, quality reference mAs of 300, beam collimationmore » of 64*0.6 mm. The rotation time was set to 0.5 sec for S64 and 1.0 sec for AS. We also scanned an anthropomorphic skull and chest phantom under routine Brain-Neck CTA protocol with the two scanners and extracted the tube current values from the raw projection data. Results: The mean CTDIvol and DLP in Brain-Neck CTA was 72 mGy and 2554 mGy*cm for AS, which was substantially larger than the mean values of 46 mGy and 1699 mGy*cm for S64. The maximum tube current was 583 mA for most cases on the S64 while the maximum was 666 mA for AS even though the rotation time set for AS was 1.0 sec. Measurements obtained with the anthropomorphic phantom showed that the tube current reached 583 mA at the shoulder region for S64 while it reached to 666 mA for AS. Conclusion: The results of this study showed that substantially different CT doses can Result from Brain-Neck CTA protocols even when similar scanners and similar settings are used. Though both scanners have a similar maximum mA rating, differences in mA were observed through the shoulders, resulting in substantially different CTDIvol values.« less

Cardiac volumetry in patients with heart failure and reduced ejection fraction: a comparative study correlating multi-slice computed tomography and magnetic resonance tomography. Reasons for intermodal disagreement.

PubMed

Schroeder, Janina; Peterschroeder, Andreas; Vaske, Bernhard; Butz, Thomas; Barth, Peter; Oldenburg, Olaf; Bitter, Thomas; Burchert, Wolfgang; Horstkotte, Dieter; Langer, Christoph

2009-11-01

In humans with normal hearts multi-slice computed tomography (MSCT) based volumetry was shown to correlate well with the gold standard, cardiac magnetic resonance imaging (CMR). We correlated both techniques in patients with various degrees of heart failure and reduced ejection fraction (HFREF) resulting from cardiac dilatation. Twenty-four patients with a left ventricular enddiastolic volume (LV-EDV) of C 150 ml measured by angiography underwent MSCT and CMR scanning for left and right ventricular (LV, RV) volumetry. MSCT based short cardiac axis views were obtained beginning at the cardiac base advancing to the apex. These were reconstructed in 20 different time windows of the RR-interval (0-95%) serving for identification of enddiastole (ED) and end-systole (ES) and for planimetry. ED and ES volumes and the ejection fraction (EF) were calculated for LV and RV. MSCT based volumetry was compared with CMR. MSCT based LV volumetry significantly correlates with CMR as follows: LV-EDV r = 0.94, LV-ESV r = 0.98 and LV-EF r = 0.93, but significantly overestimates LV-EDV and LV-ESV and underestimates EF (P \\ 0.0001). MSCT based RV volumetry significantly correlates with CMR as follows: RV-EDV r = 0.79, RVESV r = 0.78 and RV-EF r = 0.73, but again significantly overestimates RV-EDV and RV-ESV and underestimates RV-EF (P \\ 0.0001). When compared with CMR a continuous overestimation of volumes and underestimation of EF needs to be considered when applying MSCT in HFREF patients.

Clinical challenges in the implementation of a tomotherapy service for head and neck cancer patients in a regional UK radiotherapy centre.

PubMed

Chatterjee, S; Mott, J H; Smyth, G; Dickson, S; Dobrowsky, W; Kelly, C G

2011-04-01

Intensity-modulated radiotherapy (IMRT) is increasingly being used to treat head and neck cancer cases. We discuss the clinical challenges associated with the setting up of an image guided intensity modulated radiotherapy service for a subset of head and neck cancer patients, using a recently commissioned helical tomotherapy (HT) Hi Art (Tomotherapy Inc, WI) machine in this article. We also discuss the clinical aspects of the tomotherapy planning process, treatment and image guidance experiences for the first 10 head and neck cancer cases. The concepts of geographical miss along with tomotherapy-specific effects, including that of field width and megavoltage CT (MVCT) imaging strategy, have been highlighted using the first 10 head and neck cases treated. There is a need for effective streamlining of all aspects of the service to ensure compliance with cancer waiting time targets. We discuss how patient toxicity audits are crucial to guide refinement of the newly set-up planning dose constraints. This article highlights the important clinical issues one must consider when setting up a head and neck IMRT, image-guided radiotherapy service. It shares some of the clinical challenges we have faced during the setting up of a tomotherapy service. Implementation of a clinical tomotherapy service requires a multidisciplinary team approach and relies heavily on good team working and effective communication between different staff groups.

Patterns of local-regional recurrence following parotid-sparing conformal and segmental intensity-modulated radiotherapy for head and neck cancer.

PubMed

Dawson, L A; Anzai, Y; Marsh, L; Martel, M K; Paulino, A; Ship, J A; Eisbruch, A

2000-03-15

To analyze the patterns of local-regional recurrence in patients with head and neck cancer treated with parotid-sparing conformal and segmental intensity-modulated radiotherapy (IMRT). Fifty-eight patients with head and neck cancer were treated with bilateral neck radiation (RT) using conformal or segmental IMRT techniques, while sparing a substantial portion of one parotid gland. The targets for CT-based RT planning included the gross tumor volume (GTV) (primary tumor and lymph node metastases) and the clinical target volume (CTV) (postoperative tumor bed, expansions of the GTVs and lymph node groups at risk of subclinical disease). Lymph node targets at risk of subclinical disease included the bilateral jugulodigastric and lower jugular lymph nodes, bilateral retropharyngeal lymph nodes at risk, and high jugular nodes at the base of skull in the side of the neck at highest risk (containing clinical neck metastases and/or ipsilateral to the primary tumor). The CTVs were expanded by 5 mm to yield planning target volumes (PTVs). Planning goals included coverage of all PTVs (with a minimum of 95% of the prescribed dose) and sparing of a substantial portion of the parotid gland in the side of the neck at less risk. The median RT doses to the gross tumor, the operative bed, and the subclinical disease PTVs were 70.4 Gy, 61.2 Gy, and 50.4 Gy respectively. All recurrences were defined on CT scans obtained at the time of recurrence, transferred to the pretreatment CT dataset used for RT planning, and analyzed using dose-volume histograms. The recurrences were classified as 1) "in-field," in which 95% or more of the recurrence volume (V(recur)) was within the 95% isodose; 2) "marginal," in which 20% to 95% of V(recur) was within the 95% isodose; or 3) "outside," in which less than 20% of V(recur) was within the 95% isodose. With a median follow-up of 27 months (range 6 to 60 months), 10 regional recurrences, 5 local recurrences (including one noninvasive recurrence) and 1 stomal recurrence were seen in 12 patients, for a 2-year actuarial local-regional control rate of 79% (95% confidence interval 68-90%). Ten patients (80%) relapsed in-field (in areas of previous gross tumor in nine patients), and two patients developed marginal recurrences in the side of the neck at highest risk (one in the high retropharyngeal nodes/base of skull and one in the submandibular nodes). Four regional recurrences extended superior to the jugulodigastric node, in the high jugular and retropharyngeal nodes near the base of skull of the side of the neck at highest risk. Three of these were in-field, in areas that had received the dose intended for subclinical disease. No recurrences were seen in the nodes superior to the jugulodigastric nodes in the side of the neck at less risk, where RT was partially spared. The majority of local-regional recurrences after conformal and segmental IMRT were "in-field," in areas judged to be at high risk at the time of RT planning, including the GTV, the operative bed, and the first echelon nodes. These findings motivate studies of dose escalation to the highest risk regions.

Improving IMRT delivery efficiency using intensity limits during inverse planning.

PubMed

Coselmon, Martha M; Moran, Jean M; Radawski, Jeffrey D; Fraass, Benedick A

2005-05-01

Inverse planned intensity modulated radiotherapy (IMRT) fields can be highly modulated due to the large number of degrees of freedom involved in the inverse planning process. Additional modulation typically results in a more optimal plan, although the clinical rewards may be small or offset by additional delivery complexity and/or increased dose from transmission and leakage. Increasing modulation decreases delivery efficiency, and may lead to plans that are more sensitive to geometrical uncertainties. The purpose of this work is to assess the use of maximum intensity limits in inverse IMRT planning as a simple way to increase delivery efficiency without significantly affecting plan quality. Nine clinical cases (three each for brain, prostate, and head/neck) were used to evaluate advantages and disadvantages of limiting maximum intensity to increase delivery efficiency. IMRT plans were generated using in-house protocol-based constraints and objectives for the brain and head/neck, and RTOG 9406 dose volume objectives in the prostate. Each case was optimized at a series of maximum intensity ratios (the product of the maximum intensity and the number of beams divided by the prescribed dose to the target volume), and evaluated in terms of clinical metrics, dose-volume histograms, monitor units (MU) required per fraction (SMLC and DMLC delivery), and intensity map variation (a measure of the beam modulation). In each site tested, it was possible to reduce total monitor units by constraining the maximum allowed intensity without compromising the clinical acceptability of the plan. Monitor unit reductions up to 38% were observed for SMLC delivery, while reductions up to 29% were achieved for DMLC delivery. In general, complicated geometries saw a smaller reduction in monitor units for both delivery types, although DMLC delivery required significantly more monitor units in all cases. Constraining the maximum intensity in an inverse IMRT plan is a simple way to improve delivery efficiency without compromising plan objectives.

Dose to Larynx Predicts for Swallowing Complications After Intensity-Modulated Radiotherapy

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

Caglar, Hale B.; Tishler, Roy B.; Othus, Megan

2008-11-15

Purpose: To evaluate early swallowing after intensity-modulated radiotherapy for head and neck squamous cell carcinoma and determine factors correlating with aspiration and/or stricture. Methods and Materials: Consecutive patients treated with intensity-modulated radiotherapy with or without chemotherapy between September 2004 and August 2006 at the Dana Farber Cancer Institute/Brigham and Women's Hospital were evaluated with institutional review board approval. Patients underwent swallowing evaluation after completion of therapy; including video swallow studies. The clinical- and treatment-related variables were examined for correlation with aspiration or strictures, as well as doses to the larynx, pharyngeal constrictor muscles, and cervical esophagus. The correlation was assessedmore » with logistic regression analysis. Results: A total of 96 patients were evaluated. Their median age was 55 years, and 79 (82%) were men. The primary site of cancer was the oropharynx in 43, hypopharynx/larynx in 17, oral cavity in 13, nasopharynx in 11, maxillary sinus in 2, and unknown primary in 10. Of the 96 patients, 85% underwent definitive RT and 15% postoperative RT. Also, 28 patients underwent induction chemotherapy followed by concurrent chemotherapy, 59 received concurrent chemotherapy, and 9 patients underwent RT alone. The median follow-up was 10 months. Of the 96 patients, 31 (32%) had clinically significant aspiration and 36 (37%) developed a stricture. The radiation dose-volume metrics, including the volume of the larynx receiving {>=}50 Gy (p = 0.04 and p = 0.03, respectively) and volume of the inferior constrictor receiving {>=}50 Gy (p = 0.05 and p = 0.02, respectively) were significantly associated with both aspiration and stricture. The mean larynx dose correlated with aspiration (p = 0.003). Smoking history was the only clinical factor to correlate with stricture (p = 0.05) but not aspiration. Conclusion: Aspiration and stricture are common side effects after intensity-modulated radiotherapy for head-and-neck squamous cell carcinoma. The dose given to the larynx and inferior constrictors correlated with these side effects.« less

SU-E-T-424: Dosimetric Verification of Modulated Electron Radiation Therapy Delivered Using An Electron Specific Multileaf Collimator for Treatment of Scalp Cases

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

Eldib, A; Al-Azhar University Cairo; Jin, L

2014-06-01

Purpose: Modulated electron radiotherapy (MERT) has the potential to achieve better treatment outcome for shallow tumors such as those of breast and scalp. In a separate study with scalp lesions, MERT was compared to volumetric modulated arc therapy. Our results showed a reduction in the dose reaching the brain with MERT. However dose calculation accuracy and delivery efficiency challenges remain. Thus in the current study we proceed to add more cases to demonstrate MERT beneficial outcome and its delivery accuracy using an electron specific multileaf collimator (eMLC). Methods: We have used the MCBEAM code for treatment head simulation and formore » generating phase space files to be used as radiation source input for our Monte Carlo based treatment planning system (MC TPS). MCPLAN code is used for calculation of patient specific dose deposition coefficient and for final MERT plan dose calculation. An in-house developed optimization code is used for the optimization process. MERT plans were generated for real patients and head and neck phantom. Film was used for dosimetric verification. The film was cut following the contour of the curved phantom surface and then sealed with black masking tape. In the measurement, the sealed film packet was sandwiched between two adjacent slabs of the head and neck phantom. The measured 2D dose distribution was then compared with calculations. Results: The eMLC allows effective treatment of scalps with multi-lesions spreading around the patient head, which was usually difficult to plan or very time consuming with conventional applicators. MERT continues to show better reduction in the brain dose. The dosimetric measurements showed slight discrepancy, which was attributed to the film setup. Conclusion: MERT can improve treatment plan quality for patients with scalp cancers. Our in-house MC TPS is capable of performing treatment planning and accurate dose calculation for MERT using the eMLC.« less

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

Chen, Chin-Cheng; Lee, Chen-Chiao, E-mail: joelee168@hotmail.co; Mah, Dennis

Because of the dose limit for critical structures such as brainstem and spinal cord, administering a dose of 60 Gy to patients with recurrent head and neck cancer is challenging for those who received a previous dose of 60-70 Gy. Specifically, previously irradiated head and neck patients may have received doses close to the tolerance limit to their brainstem and spinal cord. In this study, a reproducible intensity-modulated radiation therapy (IMRT) treatment design is presented to spare the doses to brainstem and spinal cord, with no compromise of prescribed dose delivery. Between July and November 2008, 7 patients with previouslymore » irradiated, recurrent head and neck cancers were treated with IMRT. The jaws of each field were set fixed with the goal of shielding the brainstem and spinal cord at the sacrifice of partial coverage of the planning target volume (PTV) from any particular beam orientation. Beam geometry was arranged to have sufficient coverage of the PTV and ensure that the constraints of spinal cord <10 Gy and brainstem <15 Gy were met. The mean maximum dose to the brainstem was 12.1 Gy (range 6.1-17.3 Gy), and the corresponding mean maximum dose to spinal cord was 10.4 Gy (range 8.2-14.1 Gy). For most cases, 97% of the PTV volume was fully covered by the 95% isodose volume. We found empirically that if the angle of cervical spine curvature (Cobb's angle) was less than {approx}30{sup o}, patients could be treated by 18 fields. Six patients met these criteria and were treated in 25 minutes per fraction. One patient exceeded a 30{sup o} Cobb's angle and was treated by 31 fields in 45 minutes per fraction. We have demonstrated a new technique for retreatment of head and neck cancers. The angle of cervical spine curvature plays an important role in the efficiency and effectiveness of our approach.« less

Co-registration of cone beam CT and planning CT in head and neck IMRT dose estimation: a feasible adaptive radiotherapy strategy

PubMed Central

Yip, C; Thomas, C; Michaelidou, A; James, D; Lynn, R; Lei, M

2014-01-01

Objective: To investigate if cone beam CT (CBCT) can be used to estimate the delivered dose in head and neck intensity-modulated radiotherapy (IMRT). Methods: 15 patients (10 without replan and 5 with replan) were identified retrospectively. Weekly CBCT was co-registered with original planning CT. Original high-dose clinical target volume (CTV1), low-dose CTV (CTV2), brainstem, spinal cord, parotids and external body contours were copied to each CBCT and modified to account for anatomical changes. Corresponding planning target volumes (PTVs) and planning organ-at-risk volumes were created. The original plan was applied and calculated using modified per-treatment volumes on the original CT. Percentage volumetric, cumulative (planned dose delivered prior to CBCT + adaptive dose delivered after CBCT) and actual delivered (summation of weekly adaptive doses) dosimetric differences between each per-treatment and original plan were calculated. Results: There was greater volumetric change in the parotids with an average weekly difference of between −4.1% and −27.0% compared with the CTVs/PTVs (−1.8% to −5.0%). The average weekly cumulative dosimetric differences were as follows: CTV/PTV (range, −3.0% to 2.2%), ipsilateral parotid volume receiving ≥26 Gy (V26) (range, 0.5–3.2%) and contralateral V26 (range, 1.9–6.3%). In patients who required replan, the average volumetric reductions were greater: CTV1 (−2.5%), CTV2 (−6.9%), PTV1 (−4.7%), PTV2 (−11.5%), ipsilateral (−10.4%) and contralateral parotids (−12.1%), but did not result in significant dosimetric changes. Conclusion: The dosimetric changes during head and neck simultaneous integrated boost IMRT do not necessitate adaptive radiotherapy in most patients. Advances in knowledge: Our study shows that CBCT could be used for dose estimation during head and neck IMRT. PMID:24288402

Intensity-modulated radiotherapy (IMRT) for carcinoma of the maxillary sinus: A comparison of IMRT planning systems

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

Ahmed, Raef S.; Ove, Roger; Duan, Jun

2006-10-01

The treatment of maxillary sinus carcinoma with forward planning can be technically difficult when the neck also requires radiotherapy. This difficulty arises because of the need to spare the contralateral face while treating the bilateral neck. There is considerable potential for error in clinical setup and treatment delivery. We evaluated intensity-modulated radiotherapy (IMRT) as an improvement on forward planning, and compared several inverse planning IMRT platforms. A composite dose-volume histogram (DVH) was generated from a complex forward planned case. We compared the results with those generated by sliding window fixed field dynamic multileaf collimator (MLC) IMRT, using sets of coplanarmore » beams. All setups included an anterior posterior (AP) beam, and 3-, 5-, 7-, and 9-field configurations were evaluated. The dose prescription and objective function priorities were invariant. We also evaluated 2 commercial tomotherapy IMRT delivery platforms. DVH results from all of the IMRT approaches compared favorably with the forward plan. Results for the various inverse planning approaches varied considerably across platforms, despite an attempt to prescribe the therapy similarly. The improvement seen with the addition of beams in the fixed beam sliding window case was modest. IMRT is an effective means of delivering radiotherapy reliably in the complex setting of maxillary sinus carcinoma with neck irradiation. Differences in objective function definition and optimization algorithms can lead to unexpected differences in the final dose distribution, and our evaluation suggests that these factors are more significant than the beam arrangement or number of beams.« less

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.

Dosimetric Factors Associated With Long-Term Dysphagia After Definitive Radiotherapy for Squamous Cell Carcinoma of the Head and Neck

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

Caudell, Jimmy J.; Schaner, Philip E.; Desmond, Renee A.

2010-02-01

Purpose: Intensification of radiotherapy and chemotherapy for head-and-neck cancer may lead to increased rates of dysphagia. Dosimetric predictors of objective findings of long-term dysphagia were sought. Methods and Materials: From an institutional database, 83 patients were identified who underwent definitive intensity-modulated radiotherapy for squamous cell carcinoma of the head and neck, after exclusion of those who were treated for a second or recurrent head-and-neck primary lesion, had locoregional recurrence at any time, had less than 12 months of follow-up, or had postoperative radiotherapy. Dosimetric parameters were analyzed relative to three objective endpoints as a surrogate for severe long-term dysphagia: percutaneousmore » endoscopic gastrostomy (PEG) tube dependence at 12 months, aspiration on modified barium swallow, or pharyngoesophageal stricture requiring dilation. Results: Mean dose greater than 41 Gy and volume receiving 60 Gy (V{sub 60}) greater than 24% to the larynx were significantly associated with PEG tube dependence and aspiration. V{sub 60} greater than 12% to the inferior pharyngeal constrictor was also significantly associated with increased PEG tube dependence and aspiration. V{sub 65} greater than 33% to the superior pharyngeal constrictor or greater than 75% to the middle pharyngeal constrictor was associated with pharyngoesophageal stricture requiring dilation. Conclusions: Doses to the larynx and pharyngeal constrictors predicted long-term swallowing complications, even when controlled for other clinical factors. The addition of these structures to intensity-modulated radiotherapy optimization may reduce the incidence of dysphagia, although cautious clinical validation is necessary.« less

Morphometric analysis of stab wounds by MSCT and MRI after the instillation of contrast medium.

PubMed

Fais, Paolo; Cecchetto, Giovanni; Boscolo-Berto, Rafael; Toniolo, Matteo; Viel, Guido; Miotto, Diego; Montisci, Massimo; Tagliaro, Franco; Giraudo, Chiara

2016-06-01

To analyze the morphology and depth of stab wounds experimentally produced on human legs amputated for medical reasons using multislice computed tomography (MSCT) and magnetic resonance imaging (MRI) after the instillation of a single contrast medium solution (CMS). For morphological analysis, MSCT and MRI scans were performed before and after the instillation of CMS into the wound cavity. Depth measurements were performed on the sagittal view only after CMS instillation. Subsequently, each wound was dissected using the layer-by-layer technique and the depth was measured by a ruler. One-way between-groups pairwise analysis of variance (ANOVA) and Bland-Altman plot analysis were used for comparing radiological and anatomical measurements. Unenhanced MSCT images did not identify the wound channels, whereas unenhanced MRI evidenced the wound cavity in 50 % of cases. After the instillation of CMS, both MSCT and MRI depicted the wound channel in all the investigated stabbings, although the morphology of the cavity was irregular and did not resemble the shape of the blade. The radiological measurements of the wounds' depth, after the application of CMS, exhibited a high level of agreement (about 95 % at Bland-Altman plot analysis) with the anatomical measurements at dissection. A similar systematic underestimation, however, has been evidenced for MSCT (average 11.4 %; 95 % CI 7-17) and MRI (average 9.6 %; 95 % CI 6-13) data after the instillation of CMS with respect to wound dissection measurements. MSCT and MRI after the instillation of CMS can be used for depicting the morphometric features of stab wounds, although depth measurements are affected by a slight systematic underestimation compared to layer-by-layer dissection.

Non-invasive coronary angiography with multislice computed tomography. Technology, methods, preliminary experience and prospects.

PubMed

Traversi, Egidio; Bertoli, Giuseppe; Barazzoni, Giancarlo; Baldi, Maurizia; Tramarin, Roberto

2004-02-01

The recent technical developments in multislice computed tomography (MSCT), with ECG retro-gated image reconstruction, have elicited great interest in the possibility of accurate non-invasive imaging of the coronary arteries. The latest generation of MSCT systems with 8-16 rows of detectors permits acquisition of the whole cardiac volume during a single 15-20 s breath-hold with a submillimetric definition of the images and an outstanding signal-to-noise ratio. Thus the race which, between MSCT, electron beam computed tomography and cardiac magnetic resonance imaging, can best provide routine and reliable imaging of the coronary arteries in clinical practice has recommenced. Currently available MSCT systems offer different options for both cardiac image acquisition and reconstruction, including multiplanar and curved multiplanar reconstruction, three-dimensional volume rendering, maximum intensity projection, and virtual angioscopy. In our preliminary experience including 176 patients suffering from known or suspected coronary artery disease, MSCT was feasible in 161 (91.5%) and showed a sensitivity of 80.4% and a specificity of 80.3%, with respect to standard coronary angiography, in detecting critical stenosis in coronary arteries and artery or venous bypass grafts. These results correspond to a positive predictive value of 58.6% and a negative predictive value of 92.2%. The true role that MSCT is likely to play in the future in non-invasive coronary imaging is still to be defined. Nevertheless, the huge amount of data obtainable by MSCT along with the rapid technological advances, shorter acquisition times and reconstruction algorithm developments will make the technique stronger, and possible applications are expected not only for non-invasive coronary angiography, but also for cardiac function and myocardial perfusion evaluation, as an all-in-one examination.

Whole-body multislice computed tomography (MSCT) improves trauma care in patients requiring surgery after multiple trauma.

PubMed

Wurmb, T E; Quaisser, C; Balling, H; Kredel, M; Muellenbach, R; Kenn, W; Roewer, N; Brederlau, J

2011-04-01

Whole-body multislice helical CT becomes increasingly important as a diagnostic tool in patients with multiple injuries. Time gain in multiple-trauma patients who require emergency surgery might improve outcome. The authors hypothesised that whole-body multislice computed tomography (MSCT) (MSCT trauma protocol) as the initial diagnostic tool reduces the interval to start emergency surgery (tOR) if compared to conventional radiography, combined with abdominal ultrasound and organ-focused CT (conventional trauma protocol). The second goal of the study was to investigate whether the diagnostic approach chosen has an impact on outcome. The authors' level 1 trauma centre uses whole-body MSCT for initial radiological diagnostic work-up for patients with suspected multiple trauma. Before the introduction of MSCT in 2004, a conventional approach was used. Group I: data of trauma patients treated with conventional trauma protocol from 2001 to 2003. Group II: data from trauma patients treated with whole-body MSCT trauma protocol from 2004 to 2006. tOR in group I (n=155) was 120 (90-150) min (median and IQR) and 105 (85-133) min (median and IQR) in group II (n=163), respectively (p<0.05). Patients of group II had significantly more serious injuries. No difference in outcome data was found. 14 patients died in both groups within the first 30 days; five of these died within the first 24 h. A whole-body MSCT-based diagnostic approach to multiple trauma shortens the time interval to start emergency surgery in patients with multiple injuries. Mortality remained unchanged in both groups. Patients of group II were more seriously injured; an improvement of outcome might be assumed.

Predictors of Dysgeusia in Patients With Oropharyngeal Cancer Treated With Chemotherapy and Intensity Modulated Radiation Therapy

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

Sapir, Eli; Tao, Yebin; Feng, Felix

Objective(s): Dysgeusia is a significant factor reducing quality of life and worsening dysphagia in patients receiving chemoradiation therapy for head and neck cancer. The factors affecting dysgeusia severity are uncertain. We investigated the effects on patient-reported dysgeusia of doses to the oral cavity, salivary output (required to dissolve food particles), and patient-reported xerostomia. Methods and Materials: Seventy-three patients with stage III to IV oropharyngeal cancer (OPC) (N=73) receiving definitive intensity modulated radiation therapy concurrently with chemotherapy participated in a prospective, longitudinal study of quality of life (QOL), including assessment of patient-reported gustatory function by taste-related questions from the Head andmore » Neck QOL instrument (HNQOL) and the University of Washington Head and Neck-related QOL instrument (UWQOL), before therapy and periodically after treatment. At these intervals, patients also completed a validated xerostomia-specific questionnaire (XQ) and underwent unstimulated and stimulated major salivary gland flow rate measurements. Results: At 1, 3, 6, and 12 months after treatment, dysgeusia improved over time: severe dysgeusia was reported by 50%, 40%, 22%, and 23% of patients, respectively. Significant associations were found between patient-reported severe dysgeusia and radiation dose to the oral cavity (P=.005) and tongue (P=.019); normal tissue complication probability for severe dysgeusia at 3 months showed mean oral cavity D{sub 50} doses 53 Gy and 57 Gy in the HNQOL and WUQOL questionnaires, respectively, with curve slope (m) of 0.41. Measured salivary output was not statistically significantly correlated with severe taste dysfunction, whereas patient-reported XQ summary scores and xerostomia while eating scores were correlated with severe dysgeusia in the UWQOL tool (P=.04). Conclusions: Taste impairment is significantly correlated with mean radiation dose to the oral cavity. Patient-reported xerostomia, but not salivary output, was correlated with severe dysgeusia in 1 of the 2 QOL questionnaires. Reduction in oral cavity doses is likely to improve dysgeusia.« less

Non-invasive coronary angiography for patients with acute atypical chest pain discharged after negative screening including maximal negative treadmill stress test. A prospective study.

PubMed

Bonello, L; Armero, S; Jacquier, A; Com, O; Sarran, A; Sbragia, P; Panuel, M; Arques, S; Paganelli, F

2009-05-01

Among patients admitted in the emergency department for acute atypical chest pain those with an acute coronary syndrome (ACS) who are mistakenly discharged home have high mortality. A recent retrospective study has demonstrated that multislice computed tomography (MSCT) coronary angiography could improve triage of these patients. We aimed to prospectively confirm these data on patients with a negative screening including maximal treadmill stress. 30 patients discharged from the emergency department after negative screening for an ACS were included. All patients underwent MSCT angiography of the coronary artery. Patients with coronary atheroma on MSCT had an invasive coronary angiography to confirm these findings. Seven patients (23%) had obstructive coronary artery disease on MSCT. Invasive coronary angiography (ICA) confirmed the diagnosis in all patients. In patients with no previously known coronary artery disease admitted to the emergency department with atypical acute chest pain and discharged after negative screening, including maximal treadmill stress test, MSCT coronary angiography is useful for the diagnosis of obstructive coronary artery disease.

Dependences of mucosal dose on photon beams in head-and-neck intensity-modulated radiation therapy: a Monte Carlo study

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

Chow, James C.L., E-mail: james.chow@rmp.uhn.on.ca; Department of Radiation Oncology, University of Toronto, Toronto, Ontario; Department of Physics, Ryerson University, Toronto, Ontario

2012-07-01

Dependences of mucosal dose in the oral or nasal cavity on the beam energy, beam angle, multibeam configuration, and mucosal thickness were studied for small photon fields using Monte Carlo simulations (EGSnrc-based code), which were validated by measurements. Cylindrical mucosa phantoms (mucosal thickness = 1, 2, and 3 mm) with and without the bone and air inhomogeneities were irradiated by the 6- and 18-MV photon beams (field size = 1 Multiplication-Sign 1 cm{sup 2}) with gantry angles equal to 0 Degree-Sign , 90 Degree-Sign , and 180 Degree-Sign , and multibeam configurations using 2, 4, and 8 photon beams inmore » different orientations around the phantom. Doses along the central beam axis in the mucosal tissue were calculated. The mucosal surface doses were found to decrease slightly (1% for the 6-MV photon beam and 3% for the 18-MV beam) with an increase of mucosal thickness from 1-3 mm, when the beam angle is 0 Degree-Sign . The variation of mucosal surface dose with its thickness became insignificant when the beam angle was changed to 180 Degree-Sign , but the dose at the bone-mucosa interface was found to increase (28% for the 6-MV photon beam and 20% for the 18-MV beam) with the mucosal thickness. For different multibeam configurations, the dependence of mucosal dose on its thickness became insignificant when the number of photon beams around the mucosal tissue was increased. The mucosal dose with bone was varied with the beam energy, beam angle, multibeam configuration and mucosal thickness for a small segmental photon field. These dosimetric variations are important to consider improving the treatment strategy, so the mucosal complications in head-and-neck intensity-modulated radiation therapy can be minimized.« less

Conformal and intensity modulated irradiation of head and neck cancer: the potential for improved target irradiation, salivary gland function, and quality of life.

PubMed

Eisbruch, A; Dawson, L A; Kim, H M; Bradford, C R; Terrell, J E; Chepeha, D B; Teknos, T N; Anzai, Y; Marsh, L H; Martel, M K; Ten Haken, R K; Wolf, G T; Ship, J A

1999-01-01

To develop techniques which facilitate sparing of the major salivary glands while adequately treating the targets in patients requiring comprehensive bilateral neck irradiation (RT). Conformal and static, multisegmental intensity modulated (IMRT) techniques have been developed. The salivary flow rates before and periodically after RT have been measured selectively from each major salivary gland and the residual flows correlated with glands' dose volume histograms. Subjective xerostomia questionnaires have been developed and validated. The pattern of local-regional recurrences has been examined using CT scans at the time of recurrence, transferring the recurrence volumes to the planning CT scans and regenerating the dose distributions at the recurrence sites. Target coverage and dose homogeneity in IMRT treatment plans were found to be significantly better than standard RT plans. Significant parotid gland sparing was achieved. The relationships among dose, irradiated volume and saliva flow rates from the parotid glands were characterized by dose and volume thresholds. A mean dose of 26 Gy was found to be the threshold for stimulated saliva. Subjective xerostomia was significantly reduced in patients irradiated with parotid sparing techniques, compared to patients with similar tumors treated with standard RT. The large majority of recurrences occurred inside high-risk targets. Tangible gains in salivary gland sparing and target coverage are being achieved and an improvement in some measures of quality of life is suggested by our findings. A mean parotid gland dose of < or = 26 Gy should be a planning objective if significant parotid function preservation is desired. The pattern of recurrence suggests that careful escalation of the dose to targets judged to be at highest risk may improve tumor control.

A dose homogeneity and conformity evaluation between ViewRay and pinnacle-based linear accelerator IMRT treatment plans

PubMed Central

Saenz, Daniel L.; Paliwal, Bhudatt R.; Bayouth, John E.

2014-01-01

ViewRay, a novel technology providing soft-tissue imaging during radiotherapy is investigated for treatment planning capabilities assessing treatment plan dose homogeneity and conformity compared with linear accelerator plans. ViewRay offers both adaptive radiotherapy and image guidance. The combination of cobalt-60 (Co-60) with 0.35 Tesla magnetic resonance imaging (MRI) allows for magnetic resonance (MR)-guided intensity-modulated radiation therapy (IMRT) delivery with multiple beams. This study investigated head and neck, lung, and prostate treatment plans to understand what is possible on ViewRay to narrow focus toward sites with optimal dosimetry. The goal is not to provide a rigorous assessment of planning capabilities, but rather a first order demonstration of ViewRay planning abilities. Images, structure sets, points, and dose from treatment plans created in Pinnacle for patients in our clinic were imported into ViewRay. The same objectives were used to assess plan quality and all critical structures were treated as similarly as possible. Homogeneity index (HI), conformity index (CI), and volume receiving <20% of prescription dose (DRx) were calculated to assess the plans. The 95% confidence intervals were recorded for all measurements and presented with the associated bars in graphs. The homogeneity index (D5/D95) had a 1-5% inhomogeneity increase for head and neck, 3-8% for lung, and 4-16% for prostate. CI revealed a modest conformity increase for lung. The volume receiving 20% of the prescription dose increased 2-8% for head and neck and up to 4% for lung and prostate. Overall, for head and neck Co-60 ViewRay treatments planned with its Monte Carlo treatment planning software were comparable with 6 MV plans computed with convolution superposition algorithm on Pinnacle treatment planning system. PMID:24872603

A dose homogeneity and conformity evaluation between ViewRay and pinnacle-based linear accelerator IMRT treatment plans.

PubMed

Saenz, Daniel L; Paliwal, Bhudatt R; Bayouth, John E

2014-04-01

ViewRay, a novel technology providing soft-tissue imaging during radiotherapy is investigated for treatment planning capabilities assessing treatment plan dose homogeneity and conformity compared with linear accelerator plans. ViewRay offers both adaptive radiotherapy and image guidance. The combination of cobalt-60 (Co-60) with 0.35 Tesla magnetic resonance imaging (MRI) allows for magnetic resonance (MR)-guided intensity-modulated radiation therapy (IMRT) delivery with multiple beams. This study investigated head and neck, lung, and prostate treatment plans to understand what is possible on ViewRay to narrow focus toward sites with optimal dosimetry. The goal is not to provide a rigorous assessment of planning capabilities, but rather a first order demonstration of ViewRay planning abilities. Images, structure sets, points, and dose from treatment plans created in Pinnacle for patients in our clinic were imported into ViewRay. The same objectives were used to assess plan quality and all critical structures were treated as similarly as possible. Homogeneity index (HI), conformity index (CI), and volume receiving <20% of prescription dose (DRx) were calculated to assess the plans. The 95% confidence intervals were recorded for all measurements and presented with the associated bars in graphs. The homogeneity index (D5/D95) had a 1-5% inhomogeneity increase for head and neck, 3-8% for lung, and 4-16% for prostate. CI revealed a modest conformity increase for lung. The volume receiving 20% of the prescription dose increased 2-8% for head and neck and up to 4% for lung and prostate. Overall, for head and neck Co-60 ViewRay treatments planned with its Monte Carlo treatment planning software were comparable with 6 MV plans computed with convolution superposition algorithm on Pinnacle treatment planning system.

Intensity-modulated radiotherapy for nasopharyngeal carcinoma: Clinical correlation of dose to the pharyngo-esophageal axis and dysphagia

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

Fua, Tsien F.; Corry, June; Milner, Alvin D.

2007-03-15

Purpose: The aim of this study was to quantify the dose delivered to the pharyngo-esophageal axis using different intensity-modulated radiation therapy (IMRT) techniques for treatment of nasopharyngeal carcinoma and to correlate this with acute swallowing toxicity. Methods and Materials: The study population consisted of 28 patients treated with IMRT between February 2002 and August 2005: 20 with whole field IMRT (WF-IMRT) and 8 with IMRT fields junctioned with an anterior neck field with central shielding (j-IMRT). Dose to the pharyngo-esophageal axis was measured using dose-volume histograms. Acute swallowing toxicity was assessed by review of dysphagia grade during treatment and enteralmore » feeding requirements. Results: The mean pharyngo-esophageal dose was 55.2 Gy in the WF-IMRT group and 27.2 Gy in the j-IMRT group, p < 0.001. Ninety-five percent (19/20) of the WF-IMRT group developed Grade 3 dysphagia compared with 62.5% (5/8) of the j-IMRT group, p = 0.06. Feeding tube duration was a median of 38 days for the WF-IMRT group compared with 6 days for the j-IMRT group, p = 0.04. Conclusions: Clinical vigilance must be maintained when introducing new technology to ensure that unanticipated adverse effects do not result. Although newer planning systems can reduce the dose to the pharyngo-esophageal axis with WF-IMRT, the j-IMRT technique is preferred at least in patients with no gross disease in the lower neck.« less

Radiation Doses to Structures Within and Adjacent to the Larynx are Correlated With Long-Term Diet- and Speech-Related Quality of Life

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

Dornfeld, Ken; Simmons, Joel R.; Karnell, Lucy

Purpose: To test the hypothesis that radiation dose to key sites in the upper aerodigestive tract is associated with long-term functional outcome after (chemo)radiotherapy for head-and-neck cancers. Methods and Materials: This study examined the outcome for 27 patients treated with intensity-modulated radiotherapy for definitive management of their head-and-neck cancer who were disease free for at least 1 year after treatment. Head-and-neck cancer-specific quality of life (QoL) was assessed before treatment and at 1 year after treatment. Type of diet tolerated, presence of a feeding tube, and degree of weight loss 1 year after treatment were also used as outcome measures.more » Radiation doses delivered to various points along the upper aerodigestive tract, including base of tongue, lateral pharyngeal walls, and laryngeal structures, were determined from each treatment plan. Radiation doses for each of these points were tested for correlation with outcome measures. Results: Higher doses delivered to the aryepiglottic folds, false vocal cords, and lateral pharyngeal walls near the false cords correlated with a more restrictive diet, and higher doses to the aryepiglottic folds correlated with greater weight loss (p < 0.05) 1 year after therapy. Better posttreatment speech QoL scores were associated with lower doses delivered to structures within and surrounding the larynx. Conclusion: Our data show an inverse relationship between radiation dose delivered to laryngeal structures and speech and diet and QoL outcomes after definitive (chemo)radiation treatment. These findings suggest that efforts to deliver lower doses to laryngeal structures may improve outcomes after definitive (chemo)radiation therapy.« less

Intensity Modulated Radiotherapy Improves Target Coverage and Parotid Gland Sparing When Delivering Total Mucosal Irradiation in Patients With Squamous Cell Carcinoma of Head and Neck of Unknown Primary Site

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

Bhide, Shreerang; Clark, Catherine; Harrington, Kevin

2007-10-01

Head and neck squamous cell carcinoma with occult primary site represents a controversial clinical problem. Conventional total mucosal irradiation (TMI) maximizes local control, but at the expense of xerostomia. IMRT has been shown to spare salivary tissue in head and cancer patients. This study has been performed to investigate the potential of IMRT to perform nodal and TMI and also allow parotid gland sparing in this patient group. Conventional radiotherapy (CRT) and IMRT plans were produced for six patients to treat the ipsilateral (involved) post-operative neck (PTV1) and the un-operated contralateral neck and mucosal axis (PTV2). Plans were produced withmore » and without the inclusion of nasopharynx in the PTV2. The potential to improve target coverage and spare the parotid glands was investigated for the IMRT plans. There was no significant difference in the mean doses to the PTV1 using CRT and IMRT (59.7 and 60.0 respectively, p = 0.5). The maximum doses to PTV1 and PTV2 were lower for the IMRT technique as compared to CRT (P = 0.008 and P < 0.0001), respectively, and the minimum doses to PTV1 and PTV2 were significantly higher for IMRT as compared to CRT (P = 0.001 and P = 0.001), respectively, illustrating better dose homogeneity with IMRT. The mean dose to the parotid gland contralateral to PTV1 was significantly lower for IMRT (23.21 {+-} 0.7) as compared to CRT (50.5 {+-} 5.8) (P < 0.0001). There was a significant difference in parotid dose between plans with and without the inclusion of the nasopharynx. IMRT offers improved dose homogeneity in PTV1 and PTV2 and allows for parotid sparing.« less

Bone quality evaluation at dental implant site using multislice CT, micro-CT, and cone beam CT.

PubMed

Parsa, Azin; Ibrahim, Norliza; Hassan, Bassam; van der Stelt, Paul; Wismeijer, Daniel

2015-01-01

The first purpose of this study was to analyze the correlation between bone volume fraction (BV/TV) and calibrated radiographic bone density Hounsfield units (HU) in human jaws, derived from micro-CT and multislice computed tomography (MSCT), respectively. The second aim was to assess the accuracy of cone beam computed tomography (CBCT) in evaluating trabecular bone density and microstructure using MSCT and micro-CT, respectively, as reference gold standards. Twenty partially edentulous human mandibular cadavers were scanned by three types of CT modalities: MSCT (Philips, Best, the Netherlands), CBCT (3D Accuitomo 170, J Morita, Kyoto, Japan), and micro-CT (SkyScan 1173, Kontich, Belgium). Image analysis was performed using Amira (v4.1, Visage Imaging Inc., Carlsbad, CA, USA), 3Diagnosis (v5.3.1, 3diemme, Cantu, Italy), Geomagic (studio(®) 2012, Morrisville, NC, USA), and CTAn (v1.11, SkyScan). MSCT, CBCT, and micro-CT scans of each mandible were matched to select the exact region of interest (ROI). MSCT HU, micro-CT BV/TV, and CBCT gray value and bone volume fraction of each ROI were derived. Statistical analysis was performed to assess the correlations between corresponding measurement parameters. Strong correlations were observed between CBCT and MSCT density (r = 0.89) and between CBCT and micro-CT BV/TV measurements (r = 0.82). Excellent correlation was observed between MSCT HU and micro-CT BV/TV (r = 0.91). However, significant differences were found between all comparisons pairs (P < 0.001) except for mean measurement between CBCT BV/TV and micro-CT BV/TV (P = 0.147). An excellent correlation exists between bone volume fraction and bone density as assessed on micro-CT and MSCT, respectively. This suggests that bone density measurements could be used to estimate bone microstructural parameters. A strong correlation also was found between CBCT gray values and BV/TV and their gold standards, suggesting the potential of this modality in bone quality assessment at implant site. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Intra-cavitary dosimetry for IMRT head and neck treatment using thermoluminescent dosimeters in a naso-oesophageal tube.

PubMed

Gagliardi, F M; Roxby, K J; Engström, P E; Crosbie, J C

2009-06-21

Complex intensity-modulated radiation therapy (IMRT) treatment plans require rigorous quality assurance tests. The aim of this study was to independently verify the delivered dose inside the patient in the region of the treatment site. A flexible naso-gastric tube containing thermoluminescent dosimeters (TLDs) was inserted into the oesophagus via the sinus cavity before the patient's first treatment. Lead markers were also inserted into the tube in order that the TLD positions could be accurately determined from the lateral and anterior-posterior electronic portal images taken prior to treatment. The measured dose was corrected for both daily linac output variations and the estimated dose received from the portal images. The predicted dose for each TLD was determined from the treatment planning system and compared to the measured TLD doses. The results comprise 431 TLD measurements on 43 patients. The mean measured-to-predicted dose ratio was 0.988 +/- 0.011 (95% confidence interval) for measured doses above 0.2 Gy. There was a variation in this ratio when the measurements were separated into low dose (0.2-1.0 Gy), medium dose (1.0-1.8 Gy) and high dose (>1.8 Gy) measurements. The TLD-loaded, naso-oesophageal tube for in vivo dose verification is straightforward to implement, and well tolerated by patients. It provides independent reassurance of the delivered dose for head and neck IMRT.

Intra-cavitary dosimetry for IMRT head and neck treatment using thermoluminescent dosimeters in a naso-oesophageal tube

NASA Astrophysics Data System (ADS)

Gagliardi, F. M.; Roxby, K. J.; Engström, P. E.; Crosbie, J. C.

2009-06-01

Complex intensity-modulated radiation therapy (IMRT) treatment plans require rigorous quality assurance tests. The aim of this study was to independently verify the delivered dose inside the patient in the region of the treatment site. A flexible naso-gastric tube containing thermoluminescent dosimeters (TLDs) was inserted into the oesophagus via the sinus cavity before the patient's first treatment. Lead markers were also inserted into the tube in order that the TLD positions could be accurately determined from the lateral and anterior-posterior electronic portal images taken prior to treatment. The measured dose was corrected for both daily linac output variations and the estimated dose received from the portal images. The predicted dose for each TLD was determined from the treatment planning system and compared to the measured TLD doses. The results comprise 431 TLD measurements on 43 patients. The mean measured-to-predicted dose ratio was 0.988 ± 0.011 (95% confidence interval) for measured doses above 0.2 Gy. There was a variation in this ratio when the measurements were separated into low dose (0.2-1.0 Gy), medium dose (1.0-1.8 Gy) and high dose (>1.8 Gy) measurements. The TLD-loaded, naso-oesophageal tube for in vivo dose verification is straightforward to implement, and well tolerated by patients. It provides independent reassurance of the delivered dose for head and neck IMRT.

Effect of Brain Stem and Dorsal Vagus Complex Dosimetry on Nausea and Vomiting in Head and Neck Intensity-Modulated Radiation Therapy

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

Ciura, Katherine; McBurney, Michelle; Nguyen, Baongoc

Intensity-modulated radiation therapy (IMRT) is becoming the treatment of choice for many head and neck cancer patients. IMRT reduces some toxicities by reducing radiation dose to uninvolved normal tissue near tumor targets; however, other tissues not irradiated using previous 3D techniques may receive clinically significant doses, causing undesirable side effects including nausea and vomiting (NV). Irradiation of the brainstem, and more specifically, the area postrema and dorsal vagal complex (DVC), has been linked to NV. We previously reported preliminary hypothesis-generating dose effects associated with NV in IMRT patients. The goal of this study is to relate brainstem dose to NVmore » symptoms. We retrospectively studied 100 consecutive patients that were treated for oropharyngeal cancer with IMRT. We contoured the brainstem, area postrema, and DVC with the assistance of an expert diagnostic neuroradiologist. We correlated dosimetry for the 3 areas contoured with weekly NV rates during IMRT. NV rates were significantly higher for patients who received concurrent chemotherapy. Post hoc analysis demonstrated that chemoradiation cases exhibited a trend towards the same dose-response relationship with both brainstem mean dose (p = 0.0025) and area postrema mean dose (p = 0.004); however, both failed to meet statistical significance at the p {<=} 0.002 level. Duration of toxicity was also greater for chemoradiation patients, who averaged 3.3 weeks with reported Common Terminology Criteria for Adverse Events (CTC-AE), compared with an average of 2 weeks for definitive RT patients (p = 0.002). For definitive RT cases, no dose-response trend could be ascertained. The mean brainstem dose emerged as a key parameter of interest; however, no one dose parameter (mean/median/EUD) best correlated with NV. This study does not address extraneous factors that would affect NV incidence, including the use of antiemetics, nor chemotherapy dose schedule specifics before and during RT. A prospective study will be required to depict exactly how IMRT dose affects NV.« less

SU-F-T-148: Are the Approximations in Analytic Semi-Empirical Dose Calculation Algorithms for Intensity Modulated Proton Therapy for Complex Heterogeneities of Head and Neck Clinically Significant?

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

Yepes, P; UT MD Anderson Cancer Center, Houston, TX; Titt, U

2016-06-15

Purpose: Evaluate the differences in dose distributions between the proton analytic semi-empirical dose calculation algorithm used in the clinic and Monte Carlo calculations for a sample of 50 head-and-neck (H&N) patients and estimate the potential clinical significance of the differences. Methods: A cohort of 50 H&N patients, treated at the University of Texas Cancer Center with Intensity Modulated Proton Therapy (IMPT), were selected for evaluation of clinical significance of approximations in computed dose distributions. H&N site was selected because of the highly inhomogeneous nature of the anatomy. The Fast Dose Calculator (FDC), a fast track-repeating accelerated Monte Carlo algorithm formore » proton therapy, was utilized for the calculation of dose distributions delivered during treatment plans. Because of its short processing time, FDC allows for the processing of large cohorts of patients. FDC has been validated versus GEANT4, a full Monte Carlo system and measurements in water and for inhomogeneous phantoms. A gamma-index analysis, DVHs, EUDs, and TCP and NTCPs computed using published models were utilized to evaluate the differences between the Treatment Plan System (TPS) and FDC. Results: The Monte Carlo results systematically predict lower dose delivered in the target. The observed differences can be as large as 8 Gy, and should have a clinical impact. Gamma analysis also showed significant differences between both approaches, especially for the target volumes. Conclusion: Monte Carlo calculations with fast algorithms is practical and should be considered for the clinic, at least as a treatment plan verification tool.« less

DOSIMETRIC CONSEQUENCES OF USING CONTRAST-ENHANCED COMPUTED TOMOGRAPHIC IMAGES FOR INTENSITY-MODULATED STEREOTACTIC BODY RADIOTHERAPY PLANNING.

PubMed

Yoshikawa, Hiroto; Roback, Donald M; Larue, Susan M; Nolan, Michael W

2015-01-01

Potential benefits of planning radiation therapy on a contrast-enhanced computed tomography scan (ceCT) should be weighed against the possibility that this practice may be associated with an inadvertent risk of overdosing nearby normal tissues. This study investigated the influence of ceCT on intensity-modulated stereotactic body radiotherapy (IM-SBRT) planning. Dogs with head and neck, pelvic, or appendicular tumors were included in this retrospective cross-sectional study. All IM-SBRT plans were constructed on a pre- or ceCT. Contours for tumor and organs at risk (OAR) were manually constructed and copied onto both CT's; IM-SBRT plans were calculated on each CT in a manner that resulted in equal radiation fluence. The maximum and mean doses for OAR, and minimum, maximum, and mean doses for targets were compared. Data were collected from 40 dogs per anatomic site (head and neck, pelvis, and limbs). The average dose difference between minimum, maximum, and mean doses as calculated on pre- and ceCT plans for the gross tumor volume was less than 1% for all anatomic sites. Similarly, the differences between mean and maximum doses for OAR were less than 1%. The difference in dose distribution between plans made on CTs with and without contrast enhancement was tolerable at all treatment sites. Therefore, although caution would be recommended when planning IM-SBRT for tumors near "reservoirs" for contrast media (such as the heart and urinary bladder), findings supported the use of ceCT with this dose calculation algorithm for both target delineation and IM-SBRT treatment planning. © 2015 American College of Veterinary Radiology.

Salivary gland sparing and improved target irradiation by conformal and intensity modulated irradiation of head and neck cancer.

PubMed

Eisbruch, Avraham; Ship, Jonathan A; Dawson, Laura A; Kim, Hyungjin M; Bradford, Carol R; Terrell, Jeffrey E; Chepeha, Douglas B; Teknos, Theodore N; Hogikyan, Norman D; Anzai, Yoshimi; Marsh, Lon H; Ten Haken, Randall K; Wolf, Gregory T

2003-07-01

The goals of this study were to facilitate sparing of the major salivary glands while adequately treating tumor targets in patients requiring comprehensive bilateral neck irradiation (RT), and to assess the potential for improved xerostomia. Since 1994 techniques of target irradiation and locoregional tumor control with conformal and intensity modulated radiation therapy (IMRT) have been developed. In patients treated with these modalities, the salivary flow rates before and periodically after RT have been measured selectively from each major salivary gland and the residual flows correlated with glands' dose volume histograms (DVHs). In addition, subjective xerostomia questionnaires have been developed and validated. The pattern of locoregional recurrence has been examined from computed tomography (CT) scans at the time of recurrence, transferring the recurrence volumes to the planning CT scans, and regenerating the dose distributions at the recurrence sites. Treatment plans for target coverage and dose homogeneity using static, multisegmental IMRT were found to be significantly better than standard RT plans. In addition, significant parotid gland sparing was achieved in the conformal plans. The relationships among dose, irradiated volume, and the residual saliva flow rates from the parotid glands were characterized by dose and volume thresholds. A mean radiation dose of 26 Gy was found to be the threshold for preserved stimulated saliva flow. Xerostomia questionnaire scores suggested that xerostomia was significantly reduced in patients irradiated with bilateral neck, parotid-sparing RT, compared to patients with similar tumors treated with standard RT. Examination of locoregional tumor recurrence patterns revealed that the large majority of recurrences occurred inside targets, in areas that had been judged to be at high risk and that had received RT doses according to the perceived risk. Tangible gains in salivary gland sparing and target coverage are being achieved, and an improvement in some measures of quality of life is suggested by our findings. Additional reduction of xerostomia may be achieved by further sparing of the salivary glands and the non-involved oral cavity. A mean parotid gland dose of < or = 26 Gy should be a planning objective if significant parotid function preservation is desired. The pattern of recurrence suggests that careful escalation of the dose to areas judged to be at highest risk may improve tumor control.

Risk Factors for Hearing Loss in Patients Treated With Intensity-Modulated Radiotherapy for Head-and-Neck Tumors

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

Zuur, Charlotte L.; Simis, Yvonne J.; Lamers, Emmy A.

2009-06-01

Purpose: Radiotherapy (RT) is a common treatment of head-and-neck carcinoma. The objective of this study was to perform a prospective multivariate assessment of the dose-effect relationship between intensity-modulated RT and hearing loss. Methods and Materials: Pure tone audiometry at 0.250-16 kHz was obtained before and after treatment in 101 patients (202 ears). All patients received full-course intensity-modulated RT (range, 56-70 Gy), with a median cochlear dose of 11.4 Gy (range, 0.2-69.7). Results: Audiometry was performed 1 week before and a median of 9 weeks (range, 1-112) after treatment. The mean hearing deterioration at pure tone average air-conduction 1-2-4 kHz wasmore » small (from 28.6 dB HL to 30.1 dB HL). However, individual patients showed clinically significant hearing loss, with 10-dB threshold shift incidences of 13% and 18% at pure tone averages air-conduction 1-2-4 kHz and 8-10-12.5 kHz, respectively. Post-treatment hearing capability was unfavorable in the case of greater inner ear radiation doses (p <0.0001), unfavorable baseline hearing capability (p <0.0001), green-eyed patients (p <0.0001), and older age (p <0.0001). Using multivariate analysis, a prediction of individual hearing capabiltity after treatment was made. Conclusion: RT-induced hearing loss in the mean population is modest. However, clinically significant hearing loss was observed in older patients with green eyes and unfavorable pretreatment hearing. In these patients, the intended radiation dose may be adjusted according to the proposed predictive model, aiming to decrease the risk of ototoxicity.« less

Dose–volume-related dysphagia after constrictor muscles definition in head and neck cancer intensity-modulated radiation treatment

PubMed Central

Mazzola, R; Ricchetti, F; Fiorentino, A; Fersino, S; Giaj Levra, N; Naccarato, S; Sicignano, G; Albanese, S; Di Paola, G; Alterio, D; Ruggieri, R

2014-01-01

Objective: Dysphagia remains a side effect influencing the quality of life of patients with head and neck cancer (HNC) after radiotherapy. We evaluated the relationship between planned dose involvement and acute and late dysphagia in patients with HNC treated with intensity-modulated radiation therapy (IMRT), after a recontouring of constrictor muscles (PCs) and the cricopharyngeal muscle (CM). Methods: Between December 2011 and December 2013, 56 patients with histologically proven HNC were treated with IMRT or volumetric-modulated arc therapy. The PCs and CM were recontoured. Correlations between acute and late toxicity and dosimetric parameters were evaluated. End points were analysed using univariate logistic regression. Results: An increasing risk to develop acute dysphagia was observed when constraints to the middle PCs were not respected [mean dose (Dmean) ≥50 Gy, maximum dose (Dmax) >60 Gy, V50 >70% with a p = 0.05]. The superior PC was not correlated with acute toxicity but only with late dysphagia. The inferior PC was not correlated with dysphagia; for the CM only, Dmax >60 Gy was correlated with acute dysphagia ≥ grade 2. Conclusion: According to our analysis, the superior PC has a major role, being correlated with dysphagia at 3 and 6 months after treatments; the middle PC maintains this correlation only at 3 months from the beginning of radiotherapy, but it does not have influence on late dysphagia. The inferior PC and CM have a minimum impact on swallowing symptoms. Advances in knowledge: We used recent guidelines to define dose constraints of the PCs and CM. Two results emerge in the present analysis: the superior PC influences late dysphagia, while the middle PC influences acute dysphagia. PMID:25348370

Automated IMRT planning in Pinnacle : A study in head-and-neck cancer.

PubMed

Kusters, J M A M; Bzdusek, K; Kumar, P; van Kollenburg, P G M; Kunze-Busch, M C; Wendling, M; Dijkema, T; Kaanders, J H A M

2017-12-01

This study evaluates the performance and planning efficacy of the Auto-Planning (AP) module in the clinical version of Pinnacle 9.10 (Philips Radiation Oncology Systems, Fitchburg, WI, USA). Twenty automated intensity-modulated radiotherapy (IMRT) plans were compared with the original manually planned clinical IMRT plans from patients with oropharyngeal cancer. Auto-Planning with IMRT offers similar coverage of the planning target volume as the original manually planned clinical plans, as well as better sparing of the contralateral parotid gland, contralateral submandibular gland, larynx, mandible, and brainstem. The mean dose of the contralateral parotid gland and contralateral submandibular gland could be reduced by 2.5 Gy and 1.7 Gy on average. The number of monitor units was reduced with an average of 143.9 (18%). Hands-on planning time was reduced from 1.5-3 h to less than 1 h. The Auto-Planning module was able to produce clinically acceptable head and neck IMRT plans with consistent quality.

Monte Carlo-based QA for IMRT of head and neck cancers

NASA Astrophysics Data System (ADS)

Tang, F.; Sham, J.; Ma, C.-M.; Li, J.-S.

2007-06-01

It is well-known that the presence of large air cavity in a dense medium (or patient) introduces significant electronic disequilibrium when irradiated with megavoltage X-ray field. This condition may worsen by the possible use of tiny beamlets in intensity-modulated radiation therapy (IMRT). Commercial treatment planning systems (TPSs), in particular those based on the pencil-beam method, do not provide accurate dose computation for the lungs and other cavity-laden body sites such as the head and neck. In this paper we present the use of Monte Carlo (MC) technique for dose re-calculation of IMRT of head and neck cancers. In our clinic, a turn-key software system is set up for MC calculation and comparison with TPS-calculated treatment plans as part of the quality assurance (QA) programme for IMRT delivery. A set of 10 off-the-self PCs is employed as the MC calculation engine with treatment plan parameters imported from the TPS via a graphical user interface (GUI) which also provides a platform for launching remote MC simulation and subsequent dose comparison with the TPS. The TPS-segmented intensity maps are used as input for the simulation hence skipping the time-consuming simulation of the multi-leaf collimator (MLC). The primary objective of this approach is to assess the accuracy of the TPS calculations in the presence of air cavities in the head and neck whereas the accuracy of leaf segmentation is verified by fluence measurement using a fluoroscopic camera-based imaging device. This measurement can also validate the correct transfer of intensity maps to the record and verify system. Comparisons between TPS and MC calculations of 6 MV IMRT for typical head and neck treatments review regional consistency in dose distribution except at and around the sinuses where our pencil-beam-based TPS sometimes over-predicts the dose by up to 10%, depending on the size of the cavities. In addition, dose re-buildup of up to 4% is observed at the posterior nasopharyngeal mucosa for some treatments with heavily-weighted anterior fields.

Correlating planned radiation dose to the cochlea with primary site and tumor stage in patients with head and neck cancer treated with intensity-modulated radiation therapy

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

Zhang, Jeanette; Qureshi, Muhammad M.; Kovalchuk, Nataliya

The aim of the study was to determine tumor characteristics that predict higher planned radiation (RT) dose to the cochlea in patients with head and neck cancer (HNC) treated with intensity-modulated radiotherapy (IMRT). From 2004 to 2012, 99 patients with HNC underwent definitive IMRT to a median dose of 69.96 Gy in 33 fractions, with the right and left cochlea-vestibular apparatus contoured for IMRT optimization as avoidance structures. If disease involvement was adjacent to the cochlea, preference was given to tumor coverage by prescription dose. Descriptive statistics were calculated for dose-volume histogram planning data, and mean planning dose to themore » cochlea (from left or right cochlea, receiving the greater amount of RT dose) was correlated to primary site and tumor stage. Mean (standard deviation) cochlear volume was 1.0 (0.60) cm{sup 3} with maximum and mean planned doses of 31.9 (17.5) Gy and 22.1 (13.7) Gy, respectively. Mean planned dose (Gy) to cochlea by tumor site was as follows: oral cavity (18.6, 14.4), oropharynx (21.7, 9.1), nasopharynx (36.3, 10.4), hypopharynx (14.9, 7.1), larynx (2.1, 0.62), others including the parotid gland, temporal bone, and paranasal sinus (33.6, 24.0), and unknown primary (25.6, 6.7). Average mean planned dose (Gy) to the cochlea in T0-T2 and T3-T4 disease was 22.0 and 29.2 Gy, respectively (p = 0.019). By site, a significant difference was noted for nasopharynx and others (31.6 and 50.7, p = 0.012) but not for oropharynx, oral cavity, and hypopharynx. Advanced T category predicted for higher mean cochlear dose, particularly for nasopharyngeal, parotid gland, temporal bone, and paranasal sinus HNC sites.« less

Radiotherapy dose verification on a customised head and neck perspex phantom

NASA Astrophysics Data System (ADS)

Eng, K. Y.; Kandaiya, S.; Yahaya, N. Z.

2017-05-01

IMRT dose planned for head and neck radiotherapy was verified using a customised acrylic head-and-neck phantom. The dosimeters used were calibrated Gafchromic EBT2 film and metal-oxide-semiconductor-field-effect-transistor (MOSFET). Target volumes (TV) and organs-at-risk (OAR) which were previously contoured by an oncologist on selected nasopharynx (NPC) patients were transferred to this phantom by an image fusion procedure. Three radiotherapy plans were done: Plan1 with 7-fields intensity-modulated radiotherapy (IMRT) of prescribed dose 70 Gy using 33 fractions; Plan2 with 7-fields IMRT plan at 70 Gy and 35 fractions; and Plan3 which was a mid-plane-dose (MPD) plan of 66 Gy at 33 fractions. The dose maps were first verified using MapCheck2 by SNC-PatientTM software. The passing rates from gamma analysis were 97.7% (Plan1), 93.1% (Plan2) and 100% (Plan3). Percentage difference between Treatment Planning System (TPS) calculated dose and MOSFET measured dose was comparatively higher than those from EBT2. Calculated dose and EBT2 measured doses showed differences of within the range of ±3% for TV and <±10% for OARs. However MOSFET had differences of within the range of ±6% for TV and within the range of ±10% for OARs between measured and planned doses. An overdose treatment may occur as TPS calculated doses were lower than the measured doses in these plans. This may be due to the effects of leaf leakage, leaf scatter and photon backscatter into the measuring tools (Pawlicki et al., 1999 and Ma et al., 2000). More IMRT plans have to be studied to validate this conclusion. However, the dose measurements were still within the 10% tolerance (AAPM Task Group 119). In conclusion, both GafchromicEBT2 film and MOSFET are suitable for IMRT radiotherapy dosimetry.

Patient-reported voice and speech outcomes after whole-neck intensity modulated radiation therapy and chemotherapy for oropharyngeal cancer: prospective longitudinal study.

PubMed

Vainshtein, Jeffrey M; Griffith, Kent A; Feng, Felix Y; Vineberg, Karen A; Chepeha, Douglas B; Eisbruch, Avraham

2014-08-01

To describe voice and speech quality changes and their predictors in patients with locally advanced oropharyngeal cancer treated on prospective clinical studies of organ-preserving chemotherapy-intensity modulated radiation therapy (chemo-IMRT). Ninety-one patients with stage III/IV oropharyngeal cancer were treated on 2 consecutive prospective studies of definitive chemoradiation using whole-field IMRT from 2003 to 2011. Patient-reported voice and speech quality were longitudinally assessed from before treatment through 24 months using the Communication Domain of the Head and Neck Quality of Life (HNQOL-C) instrument and the Speech question of the University of Washington Quality of Life (UWQOL-S) instrument, respectively. Factors associated with patient-reported voice quality worsening from baseline and speech impairment were assessed. Voice quality decreased maximally at 1 month, with 68% and 41% of patients reporting worse HNQOL-C and UWQOL-S scores compared with before treatment, and improved thereafter, recovering to baseline by 12-18 months on average. In contrast, observer-rated larynx toxicity was rare (7% at 3 months; 5% at 6 months). Among patients with mean glottic larynx (GL) dose ≤20 Gy, >20-30 Gy, >30-40 Gy, >40-50 Gy, and >50 Gy, 10%, 32%, 25%, 30%, and 63%, respectively, reported worse voice quality at 12 months compared with before treatment (P=.011). Results for speech impairment were similar. Glottic larynx dose, N stage, neck dissection, oral cavity dose, and time since chemo-IMRT were univariately associated with either voice worsening or speech impairment. On multivariate analysis, mean GL dose remained independently predictive for both voice quality worsening (8.1%/Gy) and speech impairment (4.3%/Gy). Voice quality worsening and speech impairment after chemo-IMRT for locally advanced oropharyngeal cancer were frequently reported by patients, underrecognized by clinicians, and independently associated with GL dose. These findings support reducing mean GL dose to as low as reasonably achievable, aiming at ≤20 Gy when the larynx is not a target. Copyright © 2014 Elsevier Inc. All rights reserved.

Patient-Reported Voice and Speech Outcomes After Whole-Neck Intensity Modulated Radiation Therapy and Chemotherapy for Oropharyngeal Cancer: Prospective Longitudinal Study

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

Vainshtein, Jeffrey M.; Griffith, Kent A.; Feng, Felix Y.

Purpose: To describe voice and speech quality changes and their predictors in patients with locally advanced oropharyngeal cancer treated on prospective clinical studies of organ-preserving chemotherapy–intensity modulated radiation therapy (chemo-IMRT). Methods and Materials: Ninety-one patients with stage III/IV oropharyngeal cancer were treated on 2 consecutive prospective studies of definitive chemoradiation using whole-field IMRT from 2003 to 2011. Patient-reported voice and speech quality were longitudinally assessed from before treatment through 24 months using the Communication Domain of the Head and Neck Quality of Life (HNQOL-C) instrument and the Speech question of the University of Washington Quality of Life (UWQOL-S) instrument, respectively.more » Factors associated with patient-reported voice quality worsening from baseline and speech impairment were assessed. Results: Voice quality decreased maximally at 1 month, with 68% and 41% of patients reporting worse HNQOL-C and UWQOL-S scores compared with before treatment, and improved thereafter, recovering to baseline by 12-18 months on average. In contrast, observer-rated larynx toxicity was rare (7% at 3 months; 5% at 6 months). Among patients with mean glottic larynx (GL) dose ≤20 Gy, >20-30 Gy, >30-40 Gy, >40-50 Gy, and >50 Gy, 10%, 32%, 25%, 30%, and 63%, respectively, reported worse voice quality at 12 months compared with before treatment (P=.011). Results for speech impairment were similar. Glottic larynx dose, N stage, neck dissection, oral cavity dose, and time since chemo-IMRT were univariately associated with either voice worsening or speech impairment. On multivariate analysis, mean GL dose remained independently predictive for both voice quality worsening (8.1%/Gy) and speech impairment (4.3%/Gy). Conclusions: Voice quality worsening and speech impairment after chemo-IMRT for locally advanced oropharyngeal cancer were frequently reported by patients, underrecognized by clinicians, and independently associated with GL dose. These findings support reducing mean GL dose to as low as reasonably achievable, aiming at ≤20 Gy when the larynx is not a target.« less

Parotid Gland Sparing With Helical Tomotherapy in Head-and-Neck Cancer

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

Voordeckers, Mia, E-mail: mia.voordeckers@uzbrussel.be; Farrag, Ashraf; Assiut University

Purpose: This study evaluated the ability of helical tomotherapy to spare the function of the parotid glands in patients with head-and-neck cancer by analyzing dose-volume histograms, salivary gland scintigraphy, and quality of life assessment. Methods and Materials: Data from 76 consecutive patients treated with helical tomotherapy (Hi-Art Tomotherapy) at University Hospital Brussel were analyzed. During planning, priority was given to planning target volume (PTV) coverage: {>=}95% of the dose must be delivered to {>=}95% of the PTV. Elective nodal regions received 54 Gy (1.8 Gy/fraction). A dose of 70.5 Gy (2.35 Gy/fraction) was prescribed to the primary tumor and pathologicmore » lymph nodes (simultaneous integrated boost scheme). Objective scoring of salivary excretion was performed by salivary gland scintigraphy. Subjective scoring of salivary gland function was evaluated by the European Organization for Research and Treatment of Cancer quality of life questionnaires Quality of Life Questionnaire-C30 (QLQ-C30) and Quality of Life Questionnaire-Head and Neck 35 (H and N35). Results: Analysis of dose-volume histograms (DVHs) showed excellent coverage of the PTV. The volume of PTV receiving 95% of the prescribed dose (V95%) was 99.4 (range, 96.3-99.9). DVH analysis of parotid gland showed a median value of the mean parotid dose of 32.1 Gy (range, 17.5-70.3 Gy). The median parotid volume receiving a dose <26 Gy was 51.2%. Quality of life evaluation demonstrated an initial deterioration of almost all scales and items in QLQ-C30 and QLQ-H and N35. Most items improved in time, and some reached baseline values 18 months after treatment. Conclusion: DVH analysis, scintigraphic evaluation of parotid function, and quality of life assessment of our patient group showed that helical tomotherapy makes it possible to preserve parotid gland function without compromising disease control. We recommend mean parotid doses of <34 Gy and doses <26 Gy to a maximum 47% of the parotid volume as planning goals. Intensity-modulated radiotherapy should be considered as standard treatment in patients with head-and-neck cancer.« less

Improved Dosimetric and Clinical Outcomes With Intensity-Modulated Radiotherapy for Head-and-Neck Cancer of Unknown Primary Origin

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

Chen, Allen M., E-mail: allen.chen@ucdmc.ucdavis.ed; Li Baoqing; Farwell, D. Gregory

2011-03-01

Purpose: To compare differences in dosimetric, clinical, and quality-of-life endpoints among a cohort of patients treated by intensity-modulated radiotherapy (IMRT) and conventional radiotherapy (CRT) for head-and-neck cancer of unknown primary origin. Methods and Materials: The medical records of 51 patients treated by radiation therapy for squamous cell carcinoma of the head and neck presenting as cervical lymph node metastasis of occult primary origin were reviewed. Twenty-four patients (47%) were treated using CRT, and 27 (53%) were treated using IMRT. The proportions of patients receiving concurrent chemotherapy were 54% and 63%, respectively. Results: The 2-year estimates of overall survival, local-regional control,more » and disease-specific survival for the entire patient population were 86%, 89%, and84%, respectively. There were no significant differences in any of these endpoints with respect to radiation therapy technique (p > 0.05 for all). Dosimetric analysis revealed that the use of IMRT resulted in significant improvements with respect to mean dose and V30 to the contralateral (spared) parotid gland. In addition, mean doses to the ipsilateral inner and middle ear structures were significantly reduced with IMRT (p < 0.05 for all). The incidence of severe xerostomia in the late setting was 58% and 11% among patients treated by CRT and IMRT, respectively (p < 0.001). The percentages of patients who were G-tube dependent at 6 months after treatment were 42% and 11%, respectively (p < 0.001). Conclusions: IMRT results in significant improvements in the therapeutic ratio among patients treated by radiation therapy for head-and-neck cancer of unknown primary origin.« less

Efficacy and Toxicity of Chemoradiotherapy Using Intensity-Modulated Radiotherapy for Unknown Primary of Head and Neck

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

Sher, David J., E-mail: dsher@lroc.harvard.edu; Balboni, Tracy A.; Haddad, Robert I.

2011-08-01

Purpose: No single standard treatment paradigm is available for head-and-neck squamous cell carcinoma of an unknown primary (HNCUP). Bilateral neck radiotherapy with mucosal axis irradiation is widely used, with or without chemotherapy and/or surgical resection. Intensity-modulated radiotherapy (IMRT) is a highly conformal method for delivering radiation that is becoming the standard of care and might reduce the long-term treatment-related sequelae. We report the Dana-Farber Cancer Institute experience with IMRT-based treatment for HNCUP. Patients and Materials: A retrospective study of all patients treated at the Dana-Farber Cancer Institute for HNCUP with IMRT between August 2004 and January 2009. The primary endpointmore » was overall survival; the secondary endpoints were locoregional and distant control, and acute and chronic toxicity. Results: A total of 24 patients with HNCUP were included. Of these patients, 22 had Stage N2 disease or greater. All patients underwent neck computed tomography, positron emission tomography-computed tomography, and examination under anesthesia with directed biopsies. Of the 24 patients, 22 received concurrent chemotherapy, and 7 (29%) also underwent induction chemotherapy. The median involved nodal dose was 70 Gy, and the median mucosal dose was 60 Gy. With a median follow-up of 2.1 years, the 2-year actuarial overall survival and locoregional control rate was 92% and 100%, respectively. Only 25% of the patients had Grade 2 xerostomia, although 11 patients (46%) required esophageal dilation for stricture. Conclusion: In a single-institution series, IMRT-based chemoradiotherapy for HNCUP was associated with superb overall survival and locoregional control. The xerostomia rates were promising, but the aggressive therapy was associated with significant rates of esophageal stenosis.« less

Analysis of intensity variability in multislice and cone beam computed tomography.

PubMed

Nackaerts, Olivia; Maes, Frederik; Yan, Hua; Couto Souza, Paulo; Pauwels, Ruben; Jacobs, Reinhilde

2011-08-01

The aim of this study was to evaluate the variability of intensity values in cone beam computed tomography (CBCT) imaging compared with multislice computed tomography Hounsfield units (MSCT HU) in order to assess the reliability of density assessments using CBCT images. A quality control phantom was scanned with an MSCT scanner and five CBCT scanners. In one CBCT scanner, the phantom was scanned repeatedly in the same and in different positions. Images were analyzed using registration to a mathematical model. MSCT images were used as a reference. Density profiles of MSCT showed stable HU values, whereas in CBCT imaging the intensity values were variable over the profile. Repositioning of the phantom resulted in large fluctuations in intensity values. The use of intensity values in CBCT images is not reliable, because the values are influenced by device, imaging parameters and positioning. © 2011 John Wiley & Sons A/S.

SU-E-T-184: Clinical VMAT QA Practice Using LINAC Delivery Log Files

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

Johnston, H; Jacobson, T; Gu, X

2015-06-15

Purpose: To evaluate the accuracy of volumetric modulated arc therapy (VMAT) treatment delivery dose clouds by comparing linac log data to doses measured using an ionization chamber and film. Methods: A commercial IMRT quality assurance (QA) process utilizing a DICOM-RT framework was tested for clinical practice using 30 prostate and 30 head and neck VMAT plans. Delivered 3D VMAT dose distributions were independently checked using a PinPoint ionization chamber and radiographic film in a solid water phantom. DICOM RT coordinates were used to extract the corresponding point and planar doses from 3D log file dose distributions. Point doses were evaluatedmore » by computing the percent error between log file and chamber measured values. A planar dose evaluation was performed for each plan using a 2D gamma analysis with 3% global dose difference and 3 mm isodose point distance criteria. The same analysis was performed to compare treatment planning system (TPS) doses to measured values to establish a baseline assessment of agreement. Results: The mean percent error between log file and ionization chamber dose was 1.0%±2.1% for prostate VMAT plans and −0.2%±1.4% for head and neck plans. The corresponding TPS calculated and measured ionization chamber values agree within 1.7%±1.6%. The average 2D gamma passing rates for the log file comparison to film are 98.8%±1.0% and 96.2%±4.2% for the prostate and head and neck plans, respectively. The corresponding passing rates for the TPS comparison to film are 99.4%±0.5% and 93.9%±5.1%. Overall, the point dose and film data indicate that log file determined doses are in excellent agreement with measured values. Conclusion: Clinical VMAT QA practice using LINAC treatment log files is a fast and reliable method for patient-specific plan evaluation.« less

Selective robust optimization: A new intensity-modulated proton therapy optimization strategy

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

Li, Yupeng; Niemela, Perttu; Siljamaki, Sami

2015-08-15

Purpose: To develop a new robust optimization strategy for intensity-modulated proton therapy as an important step in translating robust proton treatment planning from research to clinical applications. Methods: In selective robust optimization, a worst-case-based robust optimization algorithm is extended, and terms of the objective function are selectively computed from either the worst-case dose or the nominal dose. Two lung cancer cases and one head and neck cancer case were used to demonstrate the practical significance of the proposed robust planning strategy. The lung cancer cases had minimal tumor motion less than 5 mm, and, for the demonstration of the methodology,more » are assumed to be static. Results: Selective robust optimization achieved robust clinical target volume (CTV) coverage and at the same time increased nominal planning target volume coverage to 95.8%, compared to the 84.6% coverage achieved with CTV-based robust optimization in one of the lung cases. In the other lung case, the maximum dose in selective robust optimization was lowered from a dose of 131.3% in the CTV-based robust optimization to 113.6%. Selective robust optimization provided robust CTV coverage in the head and neck case, and at the same time improved controls over isodose distribution so that clinical requirements may be readily met. Conclusions: Selective robust optimization may provide the flexibility and capability necessary for meeting various clinical requirements in addition to achieving the required plan robustness in practical proton treatment planning settings.« less

Monte Carlo evaluation of Acuros XB dose calculation Algorithm for intensity modulated radiation therapy of nasopharyngeal carcinoma

NASA Astrophysics Data System (ADS)

Yeh, Peter C. Y.; Lee, C. C.; Chao, T. C.; Tung, C. J.

2017-11-01

Intensity-modulated radiation therapy is an effective treatment modality for the nasopharyngeal carcinoma. One important aspect of this cancer treatment is the need to have an accurate dose algorithm dealing with the complex air/bone/tissue interface in the head-neck region to achieve the cure without radiation-induced toxicities. The Acuros XB algorithm explicitly solves the linear Boltzmann transport equation in voxelized volumes to account for the tissue heterogeneities such as lungs, bone, air, and soft tissues in the treatment field receiving radiotherapy. With the single beam setup in phantoms, this algorithm has already been demonstrated to achieve the comparable accuracy with Monte Carlo simulations. In the present study, five nasopharyngeal carcinoma patients treated with the intensity-modulated radiation therapy were examined for their dose distributions calculated using the Acuros XB in the planning target volume and the organ-at-risk. Corresponding results of Monte Carlo simulations were computed from the electronic portal image data and the BEAMnrc/DOSXYZnrc code. Analysis of dose distributions in terms of the clinical indices indicated that the Acuros XB was in comparable accuracy with Monte Carlo simulations and better than the anisotropic analytical algorithm for dose calculations in real patients.

Beam Path Toxicities to Non-Target Structures During Intensity-Modulated Radiation Therapy for Head and Neck Cancer

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

Rosenthal, David I.; Chambers, Mark S.; Fuller, Clifton D.

2008-11-01

Background: Intensity-modulated radiation therapy (IMRT) beams traverse nontarget normal structures not irradiated during three-dimensional conformal RT (3D-CRT) for head and neck cancer (HNC). This study estimates the doses and toxicities to nontarget structures during IMRT. Materials and Methods: Oropharyngeal cancer IMRT and 3D-CRT cases were reviewed. Dose-volume histograms (DVH) were used to evaluate radiation dose to the lip, cochlea, brainstem, occipital scalp, and segments of the mandible. Toxicity rates were compared for 3D-CRT, IMRT alone, or IMRT with concurrent cisplatin. Descriptive statistics and exploratory recursive partitioning analysis were used to estimate dose 'breakpoints' associated with observed toxicities. Results: A totalmore » of 160 patients were evaluated for toxicity; 60 had detailed DVH evaluation and 15 had 3D-CRT plan comparison. Comparing IMRT with 3D-CRT, there was significant (p {<=} 0.002) nonparametric differential dose to all clinically significant structures of interest. Thirty percent of IMRT patients had headaches and 40% had occipital scalp alopecia. A total of 76% and 38% of patients treated with IMRT alone had nausea and vomiting, compared with 99% and 68%, respectively, of those with concurrent cisplatin. IMRT had a markedly distinct toxicity profile than 3D-CRT. In recursive partitioning analysis, National Cancer Institute's Common Toxicity Criteria adverse effects 3.0 nausea and vomiting, scalp alopecia and anterior mucositis were associated with reconstructed mean brainstem dose >36 Gy, occipital scalp dose >30 Gy, and anterior mandible dose >34 Gy, respectively. Conclusions: Dose reduction to specified structures during IMRT implies an increased beam path dose to alternate nontarget structures that may result in clinical toxicities that were uncommon with previous, less conformal approaches. These findings have implications for IMRT treatment planning and research, toxicity assessment, and multidisciplinary patient management.« less

A phase I open-label dose-escalation study of the anti-HER3 monoclonal antibody LJM716 in patients with advanced squamous cell carcinoma of the esophagus or head and neck and HER2-overexpressing breast or gastric cancer.

PubMed

Reynolds, Kerry Lynn; Bedard, Philippe L; Lee, Se-Hoon; Lin, Chia-Chi; Tabernero, Josep; Alsina, Maria; Cohen, Ezra; Baselga, José; Blumenschein, George; Graham, Donna M; Garrido-Laguna, Ignacio; Juric, Dejan; Sharma, Sunil; Salgia, Ravi; Seroutou, Abdelkader; Tian, Xianbin; Fernandez, Rose; Morozov, Alex; Sheng, Qing; Ramkumar, Thiruvamoor; Zubel, Angela; Bang, Yung-Jue

2017-09-12

Human epidermal growth factor receptor 3 (HER3) is important in maintaining epidermal growth factor receptor-driven cancers and mediating resistance to targeted therapy. A phase I study of anti-HER3 monoclonal antibody LJM716 was conducted with the primary objective to identify the maximum tolerated dose (MTD) and/or recommended dose for expansion (RDE), and dosing schedule. Secondary objectives were to characterize safety/tolerability, pharmacokinetics, pharmacodynamics, and preliminary antitumor activity. This open-label, dose-finding study comprised dose escalation, followed by expansion in patients with squamous cell carcinoma of the head and neck or esophagus, and HER2-overexpressing metastatic breast cancer or gastric cancer. During dose escalation, patients received LJM716 intravenous once weekly (QW) or every two weeks (Q2W), in 28-day cycles. An adaptive Bayesian logistic regression model was used to guide dose escalation and establish the RDE. Exploratory pharmacodynamic tumor studies evaluated modulation of HER3 signaling. Patients received LJM716 3-40 mg/kg QW and 20 mg/kg Q2W (54 patients; 36 patients at 40 mg/kg QW). No dose-limiting toxicities (DLTs) were reported during dose-escalation. One patient experienced two DLTs (diarrhea, hypokalemia [both grade 3]) in the expansion phase. The RDE was 40 mg/kg QW, providing drug levels above the preclinical minimum effective concentration. One patient with gastric cancer had an unconfirmed partial response; 17/54 patients had stable disease, two lasting >30 weeks. Down-modulation of phospho-HER3 was observed in paired tumor samples. LJM716 was well tolerated; the MTD was not reached, and the RDE was 40 mg/kg QW. Further development of LJM716 is ongoing. Clinicaltrials.gov registry number NCT01598077 (registered on 4 May, 2012).

A comparative study of accuracy of linear measurements using cone beam and multi-slice computed tomographies for evaluation of mandibular canal location in dry mandibles.

PubMed

Naser, Asieh Zamani; Mehr, Bahar Behdad

2013-01-01

Cross- sectional tomograms have been used for optimal pre-operative planning of dental implant placement. The aim of the present study was to assess the accuracy of Cone Beam Computed Tomography (CBCT) measurements of specific distances around the mandibular canal by comparing them to those obtained from Multi-Slice Computed Tomography (MSCT) images. Ten hemi-mandible specimens were examined using CBCT and MSCT. Before imaging, wires were placed at 7 locations between the anterior margin of the third molar and the anterior margin of the second premolar as reference points. Following distances were measured by two observers on each cross-sectional CBCT and MSCT image: Mandibular Width (W), Length (L), Upper Distance (UD), Lower Distance (LD), Buccal Distance (BD), and Lingual Distance (LID). The obtained data were evaluated using SPSS software, applying paired t-test and intra-class correlation coefficient (ICC). There was a significant difference between the values obtained by MSCT and CBCT measurement for all areas such as H, W, UD, LD, BD, and LID, (P < 0.001), with a difference less than 1 mm. The ICC for all distances by both techniques, measured by a single observer with a one week interval and between 2 observers was 99% and 98%, respectively. Comparing the obtained data of both techniques indicates that the difference between two techniques is 2.17% relative to MSCT. The results of this study showed that there is significant difference between measurements obtained by CBCT and MSCT. However, the difference is not clinically significant.

Is volumetric modulated arc therapy with constant dose rate a valid option in radiation therapy for head and neck cancer patients?

PubMed

Didona, Annamaria; Lancellotta, Valentina; Zucchetti, Claudio; Panizza, Bianca Moira; Frattegiani, Alessandro; Iacco, Martina; Di Pilato, Anna Concetta; Saldi, Simonetta; Aristei, Cynthia

2018-01-01

Intensity-modulated radiotherapy (IMRT) improves dose distribution in head and neck (HN) radiation therapy. Volumetric-modulated arc therapy (VMAT), a new form of IMRT, delivers radiation in single or multiple arcs, varying dose rates (VDR-VMAT) and gantry speeds, has gained considerable attention. Constant dose rate VMAT (CDR-VMAT) associated with a fixed gantry speed does not require a dedicated linear accelerator like VDR-VMAT. The present study explored the feasibility, efficiency and delivery accuracy of CDR-VMAT, by comparing it with IMRT and VDR-VMAT in treatment planning for HN cancer. Step and shoot IMRT (SS-IMRT), CDR-VMAT and VDR-VMAT plans were created for 15 HN cancer patients and were generated by Pinnacle 3 TPS (v 9.8) using 6 MV photon energy. Three PTVs were defined to receive respectively prescribed doses of 66 Gy, 60 Gy and 54 Gy, in 30 fractions. Organs at risk (OARs) included the mandible, spinal cord, brain stem, parotids, salivary glands, esophagus, larynx and thyroid. SS-IMRT plans were based on 7 co-planar beams at fixed gantry angles. CDR-VMAT and VDR-VMAT plans, generated by the SmartArc module, used a 2-arc technique: one clockwise from 182° to 178° and the other one anti-clockwise from 178° to 182°. Comparison parameters included dose distribution to PTVs ( D mean , D 2% , D 50% , D 95% , D 98% and Homogeneity Index), maximum or mean doses to OARs, specific dose-volume data, the monitor units and treatment delivery times. Compared with SS-IMRT, CDR-VMAT significantly reduced the maximum doses to PTV1 and PTV2 and significantly improved all PTV3 parameters, except D 98% and D 95% . It significantly spared parotid and submandibular glands and was associated with a lower D mean to the larynx. Compared with VDR-VMAT, CDR-VMAT was linked to a significantly better D mean , to the PTV3 but results were worse for the parotids, left submandibular gland, esophagus and mandible. Furthermore, the D mean to the larynx was also worse. Compared with SS-IMRT and VDR-VMAT, CDR-VMAT was associated with higher average monitor unit values and significantly shorter average delivery times. CDR-VMAT appeared to be a valid option in Radiation Therapy Centers that lack a dedicated linear accelerator for volumetric arc therapy with variable dose-rates and gantry velocities, and are unwilling or unable to sanction major expenditure at present but want to adopt volumetric techniques.

A comparison of mean parotid gland dose with measures of parotid gland function after radiotherapy for head-and-neck cancer: Implications for future trials

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

Roesink, Judith M.; Schipper, Maria; Busschers, Wim

2005-11-15

Purpose: To determine the most adequate parameter to measure the consequences of reducing the parotid gland dose. Methods and Materials: One hundred eight patients treated with radiotherapy for various malignancies of the head and neck were prospectively evaluated using three methods. Parotid gland function was objectively determined by measuring stimulated parotid flow using Lashley cups and scintigraphy. To assess xerostomia-related quality of life, the head-and-neck cancer module European Organization for Research and Treatment of Cancer QLQ (Quality of Life Questionnaire) H and N35 was used. Measurements took place before radiotherapy and 6 weeks and 12 months after the completion ofmore » radiotherapy. Complication was defined for each method using cutoff values. The correlation between these complications and the mean parotid gland dose was investigated to find the best measure for parotid gland function. Results: For both flow and scintigraphy data, the best definition for objective parotid gland toxicity seemed to be reduction of stimulated parotid flow to {<=}25% of the preradiotherapy flow. Of all the subjective variables, only the single item dry mouth 6 weeks after radiotherapy was found to be significant. The best correlation with the mean parotid gland dose was found for the stimulated flow measurements. The predictive ability was the highest for the time point 1 year after radiotherapy. Subjective findings did not correlate with the mean parotid dose. Conclusions: Stimulated flow measurements using Lashley cups, with a complication defined as flow {<=}25% of the preradiotherapy output, correlated best with the mean parotid gland dose. When reduction of the mean dose to the parotid gland is intended, the stimulated flow measurement is the best method for evaluating parotid gland function.« less

Log file-based patient dose calculations of double-arc VMAT for head-and-neck radiotherapy.

PubMed

Katsuta, Yoshiyuki; Kadoya, Noriyuki; Fujita, Yukio; Shimizu, Eiji; Majima, Kazuhiro; Matsushita, Haruo; Takeda, Ken; Jingu, Keiichi

2018-04-01

The log file-based method cannot display dosimetric changes due to linac component miscalibration because of the insensitivity of log files to linac component miscalibration. The purpose of this study was to supply dosimetric changes in log file-based patient dose calculations for double-arc volumetric-modulated arc therapy (VMAT) in head-and-neck cases. Fifteen head-and-neck cases participated in this study. For each case, treatment planning system (TPS) doses were produced by double-arc and single-arc VMAT. Miscalibration-simulated log files were generated by inducing a leaf miscalibration of ±0.5 mm into the log files that were acquired during VMAT irradiation. Subsequently, patient doses were estimated using the miscalibration-simulated log files. For double-arc VMAT, regarding planning target volume (PTV), the change from TPS dose to miscalibration-simulated log file dose in D mean was 0.9 Gy and that for tumor control probability was 1.4%. As for organ-at-risks (OARs), the change in D mean was <0.7 Gy and normal tissue complication probability was <1.8%. A comparison between double-arc and single-arc VMAT for PTV showed statistically significant differences in the changes evaluated by D mean and radiobiological metrics (P < 0.01), even though the magnitude of these differences was small. Similarly, for OARs, the magnitude of these changes was found to be small. Using the log file-based method for PTV and OARs, the log file-based method estimate of patient dose using the double-arc VMAT has accuracy comparable to that obtained using the single-arc VMAT. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Scintigraphic assessment of salivary function after intensity-modulated radiotherapy for head and neck cancer: correlations with parotid dose and quality of life.

PubMed

Chen, Wen-Cheng; Lai, Chia-Hsuan; Lee, Tsair-Fwu; Hung, Chao-Hsiung; Liu, Kuo-Chi; Tsai, Ming-Fong; Wang, Wen-Hung; Chen, Hungcheng; Fang, Fu-Ming; Chen, Miao-Fen

2013-01-01

We investigated salivary function using quantitative scintigraphy and sought to identify functional correlations between parotid dose and quality of life (QoL) for head and neck cancer (HNC) patients receiving intensity-modulated radiotherapy (IMRT). Between August, 2007 and June, 2008, 31 patients treated IMRT for HNC were enrolled in this prospective study. Salivary excretion function (SEF) was previously measured by salivary scintigraphy at annual intervals for 2 years after IMRT. A dose-volume histogram of each parotid gland was calculated, and the normal tissue complication probability (NTCP) was used to determine the tolerance dose. QoL was longitudinally assessed by the EORTC QLQ-C30 and H&N35 questionnaires prior to RT, and at one, three, 12 and 24 months after RT. A significant correlation was found between the reduction of SEF and the mean parotid dose measured at 1 year (correlation coefficient, R(2)=0.651) and 2 years (R(2)=0.310) after IMRT (p<0.001). The TD(50) of the parotid gland at 1 year after IMRT is 43.6 Gy, comparable to results from western countries. We further found that contralateral parotid and submandibular gland function preservation was correlated with reduced sticky saliva and a better QoL compared to the functional preservation of both parotid glands, as determined by the EORTC QLQ-H&N35 questionnaire. A significant correlation was found between the reduction of SEF and the mean parotid dose. Preservation of contralateral parotid and submandibular gland function predicts a better QoL compared to preservation of the function of both parotid glands. Copyright © 2012 Elsevier Ltd. All rights reserved.

Thyroid V50 Highly Predictive of Hypothyroidism in Head-and-Neck Cancer Patients Treated With Intensity-modulated Radiotherapy (IMRT).

PubMed

Sachdev, Sean; Refaat, Tamer; Bacchus, Ian D; Sathiaseelan, Vythialinga; Mittal, Bharat B

2017-08-01

Radiation-induced hypothyroidism affects a significant number of patients with head-and-neck squamous cell cancer (HNSCC). We examined detailed dosimetric and clinical parameters to better determine the risk of hypothyroidism in euthyroid HNSCC patients treated with intensity-modulated radiation therapy (IMRT). From 2006 to 2010, 75 clinically euthyroid patients with HNSCC were treated with sequential IMRT. The cohort included 59 men and 16 females with a median age of 55 years (range, 30 to 89 y) who were treated to a median dose of 70 Gy (range, 60 to 75 Gy) with concurrent chemotherapy in nearly all (95%) cases. Detailed thyroid dosimetric parameters including maximum dose, mean dose, and other parameters (eg, V50-percent volume receiving at least 50 Gy) were obtained. Freedom from hypothyroidism was evaluated using the Kaplan-Meier method. Univariate and multivariate analyses were conducted using Cox regression. After a median follow-up period of 50 months, 25 patients (33%) became hypothyroid. On univariate analysis, thyroid V50 was highly correlated with developing hypothyroidism (P=0.035). Other dosimetric paramaters including mean thyroid dose (P=0.11) and maximum thyroid dose (P=0.39) did not reach statistical significance. On multivariate analysis incorporating patient, tumor, and treatment variables, V50 remained highly statistically significant (P=0.037). Regardless of other factors, for V50>60%, the odds ratio of developing hypothyroidism was 6.76 (P=0.002). In HNSCC patients treated with IMRT, thyroid V50 highly predicts the risk of developing hypothyroidism. V50>60% puts patients at a significantly higher risk of becoming hypothyroid. This can be a useful dose constraint to consider during treatment planning.

Expression of Wnt and Notch signaling pathways in inflammatory bowel disease treated with mesenchymal stem cell transplantation: evaluation in a rat model.

PubMed

Xing, Yanfen; Chen, Xiaojie; Cao, Yanwen; Huang, Jianyun; Xie, Xuhong; Wei, Yaming

2015-05-22

The purpose of this study was to investigate the expression of Wnt and Notch signaling pathway-related genes in inflammatory bowel disease (IBD) treated with mesenchymal stem cell transplantation (MSCT). TNBS (2,4,6-trinitrobenzene sulfonic acid) was used to establish IBD in a rat model. Mesenchymal stem cells (MSCs) were transplanted via tail vein transfusion. Saline water was used in a control group. The expression of Wnt and Notch main signaling molecules was screened by gene chips and verified by quantitative reverse transcription-polymerase chain reaction in the IBD rat model on day 14 and day 28 after transplantation. The IBD rat models were successfully established and MSCs were transplanted into those models. Genome-wide expression profile chips identified a total of 388 differentially expressive genes, of which 191 were upregulated and 197 were downregulated in the MSC-transplanted group in comparison with the IBD control group. Real-time quantitative polymerase chain reaction results showed that the level of Olfm4 mRNA expression in the IBD group (2.54±0.20) was significantly increased compared with the MSCT group (1.39±0.54) and the normal group (1.62±0.25) (P <0.05). The Wnt3a mRNA was more highly expressed in IBD rats (2.92±0.94) and decreased in MSCT rats (0.17±0.63, P <0.05). The expression of GSK-3β mRNA was decreased in the setting of inflammation (0.65±0.04 versus 1.00±0.01 in normal group, P <0.05) but returned to normal levels after MSCT (0.81±0.17). The expression of β-catenin was observed to increase in IBD tissues (1.76±0.44) compared with normal tissues (1.00±0.01, P <0.05), but no difference was found in the MSCT group (1.12±0.36). Wnt11 declined at 14 days and returned to normal levels at 28 days in the IBD group; in comparison, a significantly lower expression was found in MSCT rats. There were no differences in the expression of Fzd3, c-myc, TCF4, and Wnt5a in inflammation, but all of those genes declined after MSCT treatment. The canonical Wnt and Notch signaling pathways are activated in IBD and may be suppressed by stem cell transplantation to differentiate into intestinal epithelium after MSCT. Moreover, the non-canonical Wnt signaling may be inhibited by canonical Wnt signaling in the setting of inflammation and may also be suppressed by MSCT.

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

Katsuta, Y; Tohoku University Graduate School of Medicine, Sendal, Miyagi; Kadoya, N

Purpose: In this study, we developed a system to calculate three dimensional (3D) dose that reflects dosimetric error caused by leaf miscalibration for head and neck and prostate volumetric modulated arc therapy (VMAT) without additional treatment planning system calculation on real time. Methods: An original system called clarkson dose calculation based dosimetric error calculation to calculate dosimetric error caused by leaf miscalibration was developed by MATLAB (Math Works, Natick, MA). Our program, first, calculates point doses at isocenter for baseline and modified VMAT plan, which generated by inducing MLC errors that enlarged aperture size of 1.0 mm with clarkson dosemore » calculation. Second, error incuced 3D dose was generated with transforming TPS baseline 3D dose using calculated point doses. Results: Mean computing time was less than 5 seconds. For seven head and neck and prostate plans, between our method and TPS calculated error incuced 3D dose, the 3D gamma passing rates (0.5%/2 mm, global) are 97.6±0.6% and 98.0±0.4%. The dose percentage change with dose volume histogram parameter of mean dose on target volume were 0.1±0.5% and 0.4±0.3%, and with generalized equivalent uniform dose on target volume were −0.2±0.5% and 0.2±0.3%. Conclusion: The erroneous 3D dose calculated by our method is useful to check dosimetric error caused by leaf miscalibration before pre treatment patient QA dosimetry checks.« less

Sparing functional anatomical structures during intensity-modulated radiotherapy: an old problem, a new solution.

PubMed

Tan, Wenyong; Han, Guang; Wei, Shaozhong; Hu, Desheng

2014-08-01

During intensity-modulated radiotherapy, an organ is usually assumed to be functionally homogeneous and, generally, its anatomical and spatial heterogeneity with respect to radiation response are not taken into consideration. However, advances in imaging and radiation techniques as well as an improved understanding of the radiobiological response of organs have raised the possibility of sparing the critical functional structures within various organs at risk during intensity-modulated radiotherapy. Here, we discuss these structures, which include the critical brain structure, or neural nuclei, and the nerve fiber tracts in the CNS, head and neck structures related to radiation-induced salivary and swallowing dysfunction, and functional structures in the heart and lung. We suggest that these structures can be used as potential surrogate organs at risk in order to minimize their radiation dose and/or irradiated volume without compromising the dose coverage of the target volume during radiation treatment.

SU-E-T-538: Evaluation of IMRT Dose Calculation Based on Pencil-Beam and AAA Algorithms.

PubMed

Yuan, Y; Duan, J; Popple, R; Brezovich, I

2012-06-01

To evaluate the accuracy of dose calculation for intensity modulated radiation therapy (IMRT) based on Pencil Beam (PB) and Analytical Anisotropic Algorithm (AAA) computation algorithms. IMRT plans of twelve patients with different treatment sites, including head/neck, lung and pelvis, were investigated. For each patient, dose calculation with PB and AAA algorithms using dose grid sizes of 0.5 mm, 0.25 mm, and 0.125 mm, were compared with composite-beam ion chamber and film measurements in patient specific QA. Discrepancies between the calculation and the measurement were evaluated by percentage error for ion chamber dose and γ〉l failure rate in gamma analysis (3%/3mm) for film dosimetry. For 9 patients, ion chamber dose calculated with AAA-algorithms is closer to ion chamber measurement than that calculated with PB algorithm with grid size of 2.5 mm, though all calculated ion chamber doses are within 3% of the measurements. For head/neck patients and other patients with large treatment volumes, γ〉l failure rate is significantly reduced (within 5%) with AAA-based treatment planning compared to generally more than 10% with PB-based treatment planning (grid size=2.5 mm). For lung and brain cancer patients with medium and small treatment volumes, γ〉l failure rates are typically within 5% for both AAA and PB-based treatment planning (grid size=2.5 mm). For both PB and AAA-based treatment planning, improvements of dose calculation accuracy with finer dose grids were observed in film dosimetry of 11 patients and in ion chamber measurements for 3 patients. AAA-based treatment planning provides more accurate dose calculation for head/neck patients and other patients with large treatment volumes. Compared with film dosimetry, a γ〉l failure rate within 5% can be achieved for AAA-based treatment planning. © 2012 American Association of Physicists in Medicine.

Impact of head and neck cancer adaptive radiotherapy to spare the parotid glands and decrease the risk of xerostomia.

PubMed

Castelli, Joel; Simon, Antoine; Louvel, Guillaume; Henry, Olivier; Chajon, Enrique; Nassef, Mohamed; Haigron, Pascal; Cazoulat, Guillaume; Ospina, Juan David; Jegoux, Franck; Benezery, Karen; de Crevoisier, Renaud

2015-01-09

Large anatomical variations occur during the course of intensity-modulated radiation therapy (IMRT) for locally advanced head and neck cancer (LAHNC). The risks are therefore a parotid glands (PG) overdose and a xerostomia increase. The purposes of the study were to estimate: - the PG overdose and the xerostomia risk increase during a "standard" IMRT (IMRTstd); - the benefits of an adaptive IMRT (ART) with weekly replanning to spare the PGs and limit the risk of xerostomia. Fifteen patients received radical IMRT (70 Gy) for LAHNC. Weekly CTs were used to estimate the dose distributions delivered during the treatment, corresponding either to the initial planning (IMRTstd) or to weekly replanning (ART). PGs dose were recalculated at the fraction, from the weekly CTs. PG cumulated doses were then estimated using deformable image registration. The following PG doses were compared: pre-treatment planned dose, per-treatment IMRTstd and ART. The corresponding estimated risks of xerostomia were also compared. Correlations between anatomical markers and dose differences were searched. Compared to the initial planning, a PG overdose was observed during IMRTstd for 59% of the PGs, with an average increase of 3.7 Gy (10.0 Gy maximum) for the mean dose, and of 8.2% (23.9% maximum) for the risk of xerostomia. Compared to the initial planning, weekly replanning reduced the PG mean dose for all the patients (p<0.05). In the overirradiated PG group, weekly replanning reduced the mean dose by 5.1 Gy (12.2 Gy maximum) and the absolute risk of xerostomia by 11% (p<0.01) (30% maximum). The PG overdose and the dosimetric benefit of replanning increased with the tumor shrinkage and the neck thickness reduction (p<0.001). During the course of LAHNC IMRT, around 60% of the PGs are overdosed of 4 Gy. Weekly replanning decreased the PG mean dose by 5 Gy, and therefore by 11% the xerostomia risk.

Value of Intensity-Modulated Radiotherapy in Stage IV Head-and-Neck Squamous Cell Carcinoma

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

Dirix, Piet, E-mail: piet.dirix@uzleuven.b; Nuyts, Sandra

2010-12-01

Purpose: To review outcome and toxicity of Stage IVa and IVb head-and-neck squamous cell carcinoma patients treated with concomitant chemotherapy and intensity-modulated radiotherapy (IMRT) according to a hybrid fractionation schedule. Methods and Materials: Between 2006 and 2008, 42 patients with Stage IV head-and-neck squamous cell carcinoma were irradiated according to a hybrid fractionation schedule consisting of 20 fractions of 2 Gy (once daily), followed by 20 fractions of 1.6 Gy (twice daily), to a total dose of 72 Gy. Chemotherapy (cisplatinum, 100mg/m{sup 2}) was administered at the start of Weeks 1 and 4. Treatment outcome and toxicity were retrospectively comparedmore » with a previous patient group (n = 55), treated according to the same schedule, but without intensity modulation. Results: Locoregional control (LRC) and overall survival were 81% and 56% after 2 years, respectively. In comparison with the previous cohort, no significant differences were observed regarding either LRC (66%, p = 0.38) or overall survival (73%, p = 0.29). No Grade 4 or 5 toxicity was reported in the IMRT group, either acute or chronic. The use of IMRT significantly reduced the incidence of late Grade 2 or 3 xerostomia (52.9% vs. 90.2%, p < 0.001). No difference was observed regarding late Grade 2 or 3 dysphagia (p = 0.66). Conclusions: Intensity-modulated chemoradiotherapy does not compromise LRC and significantly reduces late toxicity, especially regarding xerostomia.« less

Clinical implications of immediate or later periportal edema in MS-CT trauma scans: surrogate parameter of intravenous fluid status and venous congestion.

PubMed

Kleber, C; Buschmann, C T

2013-06-01

Periportal edema (PPE) of the liver in multislice computed tomography (MS-CT) scans that develops immediately (primary PPE [pPPE]) or later (secondary PPE [sPPE]) is not uncommon in severe trauma patients. Although PPE may serve as a marker for blunt abdominal trauma (22-31 % of cases), distinct causes and clinical implications of PPE are unclear. We analyzed the incidence of pPPE and sPPE in 68 MS-CT scans in severe trauma patients (2007-2009). Exclusion criteria were severely burned patients and patients with preexistent liver diseases predisposing to PPE. We divided PPE+ patients into two subpopulations-either initial/primary PPE (pPPE+) or later/secondary PPE (sPPE+). Further patient data were collected and statistically analyzed. PPE+ was found in 27.9 % (n = 19). Females predominated (p = 0.01), and PPE+ patients presented with a significantly better pH at admission (p = 0.008). The total amount of volume resuscitation (1,983 ± 1,155 ml; p = 0.02) and crystalloids (1,117 ± 796 ml; p = 0.006) administered before MS-CT scans was significantly higher in PPE+, whereas the amount of administered colloids (797 ± 640 ml) showed no significant difference in both groups. PPE+ was not associated with further patient data, i.e., trauma mechanism, injury severity, prognosis-relevant factors, adverse clinical events, or mortality. pPPE+ in MS-CT may serve as a surrogate parameter for intravenous volume load and/or venous congestion, and sPPE+ may also indicate venous congestion and right heart failure after severe trauma. In severe trauma patients with pPPE+/sPPE+ in MS-CT scans, causes of PPE relating to intravenous fluid overload and/or venous congestion should be excluded or treated.

Computed Tomography Number Changes Observed During Computed Tomography–Guided Radiation Therapy for Head and Neck Cancer

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

Feng, Mei; Department of Radiation Oncology, Sichuan Cancer Hospital, Chengdu; Yang, Cungeng

2015-04-01

Purpose: To investigate CT number (CTN) changes in gross tumor volume (GTV) and organ at risk (OAR) according to daily diagnostic-quality CT acquired during CT-guided intensity modulated radiation therapy for head and neck cancer (HNC) patients. Methods and Materials: Computed tomography scans acquired using a CT-on-rails during daily CT-guided intensity modulated radiation therapy for 15 patients with stage II to IVa squamous cell carcinoma of the head and neck were analyzed. The GTV, parotid glands, spinal cord, and nonspecified tissue were generated on each selected daily CT. The changes in CTN distributions and the mean and mode values were collected.more » Pearson analysis was used to assess the correlation between the CTN change, organ volume reduction, and delivered radiation dose. Results: Volume and CTN changes for GTV and parotid glands can be observed during radiation therapy delivery for HNC. The mean (±SD) CTNs in GTV and ipsi- and contralateral parotid glands were reduced by 6 ± 10, 8 ± 7, and 11 ± 10 Hounsfield units, respectively, for all patients studied. The mean CTN changes in both spinal cord and nonspecified tissue were almost invisible (<2 Hounsfield units). For 2 patients studied, the absolute mean CTN changes in GTV and parotid glands were strongly correlated with the dose delivered (P<.001 and P<.05, respectively). For the correlation between CTN reductions and delivered isodose bins for parotid glands, the Pearson coefficient varied from −0.98 (P<.001) in regions with low-dose bins to 0.96 (P<.001) in high-dose bins and were patient specific. Conclusions: The CTN can be reduced in tumor and parotid glands during the course of radiation therapy for HNC. There was a fair correlation between CTN reduction and radiation doses for a subset of patients, whereas the correlation between CTN reductions and volume reductions in GTV and parotid glands were weak. More studies are needed to understand the mechanism for the radiation-induced CTN changes.« less

Automated tube voltage adaptation in head and neck computed tomography between 120 and 100 kV: effects on image quality and radiation dose.

PubMed

May, Matthias S; Kramer, Manuel R; Eller, Achim; Wuest, Wolfgang; Scharf, Michael; Brand, Michael; Saake, Marc; Schmidt, Bernhard; Uder, Michael; Lell, Michael M

2014-09-01

Low tube voltage allows for computed tomography (CT) imaging with increased iodine contrast at reduced radiation dose. We sought to evaluate the image quality and potential dose reduction using a combination of attenuation based tube current modulation (TCM) and automated tube voltage adaptation (TVA) between 100 and 120 kV in CT of the head and neck. One hundred thirty consecutive patients with indication for head and neck CT were examined with a 128-slice system capable of TCM and TVA. Reference protocol was set at 120 kV. Tube voltage was reduced to 100 kV whenever proposed by automated analysis of the localizer. An additional small scan aligned to the jaw was performed at a fixed 120 kV setting. Image quality was assessed by two radiologists on a standardized Likert-scale and measurements of signal- (SNR) and contrast-to-noise ratio (CNR). Radiation dose was assessed as CTDIvol. Diagnostic image quality was excellent in both groups and did not differ significantly (p = 0.34). Image noise in the 100 kV data was increased and SNR decreased (17.8/9.6) in the jugular veins and the sternocleidomastoid muscle when compared to 120 kV (SNR 24.4/10.3), but not in fatty tissue and air. However, CNR did not differ statistically significant between 100 (23.5/14.4/9.4) and 120 kV data (24.2/15.3/8.6) while radiation dose was decreased by 7-8%. TVA between 100 and 120 kV in combination with TCM led to a radiation dose reduction compared to TCM alone, while keeping CNR constant though maintaining diagnostic image quality.

3D-MSCT imaging of bullet trajectory in 3D crime scene reconstruction: two case reports.

PubMed

Colard, T; Delannoy, Y; Bresson, F; Marechal, C; Raul, J S; Hedouin, V

2013-11-01

Postmortem investigations are increasingly assisted by three-dimensional multi-slice computed tomography (3D-MSCT) and have become more available to forensic pathologists over the past 20years. In cases of ballistic wounds, 3D-MSCT can provide an accurate description of the bullet location, bone fractures and, more interestingly, a clear visual of the intracorporeal trajectory (bullet track). These forensic medical examinations can be combined with tridimensional bullet trajectory reconstructions created by forensic ballistic experts. These case reports present the implementation of tridimensional methods and the results of 3D crime scene reconstruction in two cases. The authors highlight the value of collaborations between police forensic experts and forensic medicine institutes through the incorporation of 3D-MSCT data in a crime scene reconstruction, which is of great interest in forensic science as a clear visual communication tool between experts and the court. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Liver metastases: imaging considerations for protocol development with Multislice CT (MSCT)

PubMed Central

Silverman, Paul M

2006-01-01

Conventional, single-slice helical computed tomography (SSCT) allowed for scanning the majority of the liver during the critical portal venous phase. This was often referred to as the ‘optimal temporal window’. The introduction of current day multislice CT (MSCT) now allows us to acquire images in a much shorter time and more precisely than ever before. This yields increased conspicuity between low attenuation lesions and the enhanced normal liver parenchyma and optimal imaging for the vast majority of hepatic hypovascular metastases. Most importantly, these scanners, when compared to conventional non-helical scanners, avoid impinging upon the ‘equilibrium’ phase when tumors can become isodense/invisible. MSCT also allows for true multiphase scanning during the arterial and late arterial phases for detection of hypervascular metastases. The MSCT imaging speed has increased significantly over the past years with the introduction of 32- and 64-detector systems and will continue to increase in the future volumetric CT. This provides a number of important gains that are discussed in detail. PMID:17098650

Decapitation in reality and fine art: A review.

PubMed

Nikolić, Valentina; Savić, Slobodan; Antunović, Vaso; Marinković, Slobodan; Andrieux, Charlotte; Tomić, Irina

2017-11-01

The aim of our study was to examine all types of decapitation from forensic literature, including our own case, and to analyze the presentation of beheading in fine art, popular literature, and music. To do this, over 200 scientific articles in regard to decapitation were analyzed, as well as more than 10,000 artworks, and several hundreds of literary works and music pieces. In addition, a macroscopic examination of a decapitated victim was performed. Finally, a multislice computerized tomography (MSCT) examination of the cervical spine in two live volunteers was undertaken to present the osteological relationships. The forensic and criminal investigation revealed that a female victim was murdered by her jealous husband by applying several strikes with an axe, which resulted in an incomplete decapitation. All the main neck structures were transected, including the cervical spine, except a smaller part of the skin and soft tissue in the nuchal region. The mentioned MSCT examination in both the neutral position and flexion showed that the mandible can also be injured in a higher cervical location of the severance line. Various types of beheading were mentioned, including a homicidal, suicidal, accidental, judicial, internal, pathophysiological, and foetal ones. The status of consciousness and emotions in individuals just before and after decapitation was discussed. Finally, it was found that decapitation was the subject of many artists, and some writers and musicians. In conclusion, we presented a rare case of a homicide beheading performed with an axe. In addition, forensic importance of decapitation was discussed, as well as its great medical, social, anthropological, and artistic significance. Copyright © 2017 Elsevier B.V. All rights reserved.

Experimental flat-panel high-spatial-resolution volume CT of the temporal bone.

PubMed

Gupta, Rajiv; Bartling, Soenke H; Basu, Samit K; Ross, William R; Becker, Hartmut; Pfoh, Armin; Brady, Thomas; Curtin, Hugh D

2004-09-01

A CT scanner employing a digital flat-panel detector is capable of very high spatial resolution as compared with a multi-section CT (MSCT) scanner. Our purpose was to determine how well a prototypical volume CT (VCT) scanner with a flat-panel detector system defines fine structures in temporal bone. Four partially manipulated temporal-bone specimens were imaged by use of a prototypical cone-beam VCT scanner with a flat-panel detector system at an isometric resolution of 150 microm at the isocenter. These specimens were also depicted by state-of-the-art multisection CT (MSCT). Forty-two structures imaged by both scanners were qualitatively assessed and rated, and scores assigned to VCT findings were compared with those of MSCT. Qualitative assessment of anatomic structures, lesions, cochlear implants, and middle-ear hearing aids indicated that image quality was significantly better with VCT (P < .001). Structures near the spatial-resolution limit of MSCT (e.g., bony covering of the tympanic segment of the facial canal, the incudo-stapedial joint, the proximal vestibular aqueduct, the interscalar septum, and the modiolus) had higher contrast and less partial-volume effect with VCT. The flat-panel prototype provides better definition of fine osseous structures of temporal bone than that of currently available MSCT scanners. This study provides impetus for further research in increasing spatial resolution beyond that offered by the current state-of-the-art scanners.

The Potential Benefit of Radiotherapy with Protons in Head and Neck Cancer with Respect to Normal Tissue Sparing: A Systematic Review of Literature

PubMed Central

Bijl, Hendrik P.; Schilstra, Cornelis; Pijls-Johannesma, Madelon; Langendijk, Johannes A.

2011-01-01

Purpose. Clinical studies concerning head and neck cancer patients treated with protons reporting on radiation-induced side effects are scarce. Therefore, we reviewed the literature regarding the potential benefits of protons compared with the currently used photons in terms of lower doses to normal tissue and the potential for fewer subsequent radiation-induced side effects, with the main focus on in silico planning comparative (ISPC) studies. Materials and Methods. A literature search was performed by two independent researchers on ISPC studies that included proton-based and photon-based irradiation techniques. Results. Initially, 877 papers were retrieved and 14 relevant and eligible ISPC studies were identified and included in this review. Four studies included paranasal sinus cancer cases, three included nasopharyngeal cancer cases, and seven included oropharyngeal, hypopharyngeal, and/or laryngeal cancer cases. Seven studies compared the most sophisticated photon and proton techniques: intensity-modulated photon therapy versus intensity-modulated proton therapy (IMPT). Four studies compared different proton techniques. All studies showed that protons had a lower normal tissue dose, while keeping similar or better target coverage. Two studies found that these lower doses theoretically translated into a significantly lower incidence of salivary dysfunction. Conclusion. The results of ISPC studies indicate that protons have the potential for a significantly lower normal tissue dose, while keeping similar or better target coverage. Scanned IMPT probably offers the most advantage and will allow for a substantially lower probability of radiation-induced side effects. The results of these ISPC studies should be confirmed in properly designed clinical trials. PMID:21349950

Optimization of combined electron and photon beams for breast cancer

NASA Astrophysics Data System (ADS)

Xiong, W.; Li, J.; Chen, L.; Price, R. A.; Freedman, G.; Ding, M.; Qin, L.; Yang, J.; Ma, C.-M.

2004-05-01

Recently, intensity-modulated radiation therapy and modulated electron radiotherapy have gathered a growing interest for the treatment of breast and head and neck tumours. In this work, we carried out a study to combine electron and photon beams to achieve differential dose distributions for multiple target volumes simultaneously. A Monte Carlo based treatment planning system was investigated, which consists of a set of software tools to perform accurate dose calculation, treatment optimization, leaf sequencing and plan analysis. We compared breast treatment plans generated using this home-grown optimization and dose calculation software for different treatment techniques. Five different planning techniques have been developed for this study based on a standard photon beam whole breast treatment and an electron beam tumour bed cone down. Technique 1 includes two 6 MV tangential wedged photon beams followed by an anterior boost electron field. Technique 2 includes two 6 MV tangential intensity-modulated photon beams and the same boost electron field. Technique 3 optimizes two intensity-modulated photon beams based on a boost electron field. Technique 4 optimizes two intensity-modulated photon beams and the weight of the boost electron field. Technique 5 combines two intensity-modulated photon beams with an intensity-modulated electron field. Our results show that technique 2 can reduce hot spots both in the breast and the tumour bed compared to technique 1 (dose inhomogeneity is reduced from 34% to 28% for the target). Techniques 3, 4 and 5 can deliver a more homogeneous dose distribution to the target (with dose inhomogeneities for the target of 22%, 20% and 9%, respectively). In many cases techniques 3, 4 and 5 can reduce the dose to the lung and heart. It is concluded that combined photon and electron beam therapy may be advantageous for treating breast cancer compared to conventional treatment techniques using tangential wedged photon beams followed by a boost electron field.

IMRT head and neck treatment planning with a commercially available Monte Carlo based planning system

NASA Astrophysics Data System (ADS)

Boudreau, C.; Heath, E.; Seuntjens, J.; Ballivy, O.; Parker, W.

2005-03-01

The PEREGRINE Monte Carlo dose-calculation system (North American Scientific, Cranberry Township, PA) is the first commercially available Monte Carlo dose-calculation code intended specifically for intensity modulated radiotherapy (IMRT) treatment planning and quality assurance. In order to assess the impact of Monte Carlo based dose calculations for IMRT clinical cases, dose distributions for 11 head and neck patients were evaluated using both PEREGRINE and the CORVUS (North American Scientific, Cranberry Township, PA) finite size pencil beam (FSPB) algorithm with equivalent path-length (EPL) inhomogeneity correction. For the target volumes, PEREGRINE calculations predict, on average, a less than 2% difference in the calculated mean and maximum doses to the gross tumour volume (GTV) and clinical target volume (CTV). An average 16% ± 4% and 12% ± 2% reduction in the volume covered by the prescription isodose line was observed for the GTV and CTV, respectively. Overall, no significant differences were noted in the doses to the mandible and spinal cord. For the parotid glands, PEREGRINE predicted a 6% ± 1% increase in the volume of tissue receiving a dose greater than 25 Gy and an increase of 4% ± 1% in the mean dose. Similar results were noted for the brainstem where PEREGRINE predicted a 6% ± 2% increase in the mean dose. The observed differences between the PEREGRINE and CORVUS calculated dose distributions are attributed to secondary electron fluence perturbations, which are not modelled by the EPL correction, issues of organ outlining, particularly in the vicinity of air cavities, and differences in dose reporting (dose to water versus dose to tissue type).

Evaluation of Robustness to Setup and Range Uncertainties for Head and Neck Patients Treated With Pencil Beam Scanning Proton Therapy

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

Malyapa, Robert; Lowe, Matthew; Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester

Purpose: To evaluate the robustness of head and neck plans for treatment with intensity modulated proton therapy to range and setup errors, and to establish robustness parameters for the planning of future head and neck treatments. Methods and Materials: Ten patients previously treated were evaluated in terms of robustness to range and setup errors. Error bar dose distributions were generated for each plan, from which several metrics were extracted and used to define a robustness database of acceptable parameters over all analyzed plans. The patients were treated in sequentially delivered series, and plans were evaluated for both the first seriesmore » and for the combined error over the whole treatment. To demonstrate the application of such a database in the head and neck, for 1 patient, an alternative treatment plan was generated using a simultaneous integrated boost (SIB) approach and plans of differing numbers of fields. Results: The robustness database for the treatment of head and neck patients is presented. In an example case, comparison of single and multiple field plans against the database show clear improvements in robustness by using multiple fields. A comparison of sequentially delivered series and an SIB approach for this patient show both to be of comparable robustness, although the SIB approach shows a slightly greater sensitivity to uncertainties. Conclusions: A robustness database was created for the treatment of head and neck patients with intensity modulated proton therapy based on previous clinical experience. This will allow the identification of future plans that may benefit from alternative planning approaches to improve robustness.« less

Quantification of bone quality using different cone beam computed tomography devices: Accuracy assessment for edentulous human mandibles.

PubMed

Van Dessel, Jeroen; Nicolielo, Laura Ferreira Pinheiro; Huang, Yan; Slagmolen, Pieter; Politis, Constantinus; Lambrichts, Ivo; Jacobs, Reinhilde

To determine the accuracy of the latest cone beam computed tomography (CBCT) machines in comparison to multi-slice computer tomography (MSCT) and micro computed tomography (micro-CT) for objectively assessing trabecular and cortical bone quality prior to implant placement. Eight edentulous human mandibular bone samples were scanned with seven CBCT scanners (3D Accuitomo 170, i-CAT Next Generation, ProMax 3D Max, Scanora 3D, Cranex 3D, Newtom GiANO and Carestream 9300) and one MSCT system (Somatom Definition Flash) using the clinical exposure protocol with the highest resolution. Micro-CT (SkyScan 1174) images served as a gold standard. A volume of interest (VOI) comprising trabecular and cortical bone only was delineated on the micro-CT. After spatial alignment of all scan types, micro-CT VOIs were overlaid on the CBCT and MSCT images. Segmentation was applied and morphometric parameters were calculated for each scanner. CBCT and MSCT morphometric parameters were compared with micro-CT using mixed-effect models. Intraclass correlation analysis was used to grade the accuracy of each scanner in assessing trabecular and cortical quality in comparison with the gold standard. Bone structure patterns of each scanner were compared with micro-CT in 2D and 3D to facilitate the interpretation of the morphometric analysis. Morphometric analysis showed an overestimation of the cortical and trabecular bone quantity during CBCT and MSCT evaluation compared to the gold standard micro-CT. The trabecular thickness (Tb.Th) was found to be significantly (P < 0.05) different and the smallest overestimation was found for the ProMax 3D Max (180 µm), followed by the 3D Accuitomo 170 (200 µm), Carestream 9300 (220 µm), Newtom GiANO (240 µm), Cranex 3D (280 µm), Scanora 3D (300 µm), high resolution MSCT (310 µm), i-CAT Next Generation (430 µm) and standard resolution MSCT (510 µm). The underestimation of the cortical thickness (Ct.Th) in ProMax 3D Max (-10 µm), the overestimation in Newtom GiANO (10 µm) and the high resolution MSCT (10 µm) were neglible. However, a significant overestimation (P < 0.05) was found for 3D Accuitomo 170 (110 µm), Scanora 3D (140 µm), standard resolution MSCT (150 µm), Carestream 9300 (190 µm), Cranex 3D (190 µm) and i-CAT Next Generation (230 µm). Comparison of the 2D network and 3D surface distance confirmed the overestimation in bone quantity, but only demonstrated a deviant trabecular network for the i-CAT Next Generation and the standard resolution MSCT. Intraclass correlation coefficients (ICCs) showed a significant (P < 0.05) high intra-observer reliability (ICC > 0.70) in morphometric evaluation between micro-CT and commercially available CBCT scanners (3D Accuitomo 170, Newtom GiANO and ProMax 3D Max). The ICC for Tb.Th and Ct.Th were 0.72 and 0.98 (3D Accuitomo 170), 0.71 and 0.96 (Newtom GiANO), and 0.87 and 0.92 (ProMax 3D Max), respectively. High resolution CBCT offers a clinical alternative to MSCT to objectively determine the bone quality prior to implant placement. However, not all tested CBCT machines have sufficient resolution to accurately depict the trabecular network or cortical bone. Conflict-of-interest statement: There is no conflict of interest to declare. Fellowship support came from Research Foundation Flanders (FWO) from the Belgian government, and Coordination for the Improvement of Higher Education Personnel (CAPES) program and Science without borders from the Brazilian government.

Heart imaging: the accuracy of the 64-MSCT in the detection of coronary artery disease.

PubMed

Alessandri, N; Di Matteo, A; Rondoni, G; Petrassi, M; Tufani, F; Ferrari, R; Laghi, A

2009-01-01

At present, coronary angiography represents the gold standard technique for the diagnosis of coronary artery disease. Our aim is to compare the conventional coronary angiography to the coronary 64-multislice spiral computed tomography (64-MSCT), a new and non-invasive cardiac imaging technique. The last generation of MSCT scanners show a better imaging quality, due to a greater spatial and temporal resolution. Four expert observers (two cardiologists and two radiologists) have compared the angiographic data with the accuracy of the 64-MSCT in the detection and evaluation of coronary vessels stenoses. From the data obtained, the sensibility, the specificity and the accuracy of the coronary 64-MSCT have been defined. We have enrolled 75 patients (57 male, 18 female, mean age 61.83 +/- 10.38; range 30-80 years) with known or suspected coronary artery disease. The above population has been divided into 3 groups: Group A (Gr. A) with 40 patients (mean age 60.7 +/- 12.5) affected by both non-significant and significant coronary artery disease; Group B (Gr. B) with 25 patients (mean age 60.3 +/- 14.6) who underwent to percutaneous coronary intervention (PCI); Group C (Gr. C) with 10 patients (mean age 54.20 +/- 13.7) without any coronary angiographic stenoses. All the patients underwent non-invasive exams, conventional coronary angiography and coronary 64-MSCT. The comparison of the data obtained has been carried out according to a per group analysis, per patient analysis and per segment analysis. Moreover, the accuracy of the 64-MSCT has been defined for the detection of >75%, 50-75% and <50% coronary stenoses. Coronary angiography has identified significant coronary artery disease in 75% of the patients in the Gr. A and in 73% of the patients in the Gr. B. No coronary stenoses have been detected in Gr. C. According to a per segment analysis, in Gr. A, 36% of the segments analysed have shown a coronary stenosis (37% stenoses >75%, 32% stenoses 50-75% and 31% stenoses <50%). In Gr. B, 32% of the segments have shown a coronary stenosis (33% stenoses >75%, 29% stenoses 50-75% and 38% stenoses <50%). In-stent disease has been shown in only 4 of the 29 coronary stents identified. In Gr. A, coronary 64-MSCT has confirmed the angiographic results in the 93% of cases (sensibility 93%, specificity 100%, positive predictive value 100% and negative predictive value 83%) while, in Gr. B, this confirm has been obtained only in 64% of cases (sensibility 64%, specificity 100%, positive predictive value 100% and negative predictive value 50%). In Gr. C, we have observed a complete agreement between angiographic and CT data (sensibility, specificity, positive predictive value and negative predictive value 100%). According to a per segment analysis, the angiographic results have been confirmed in 98% of cases in Gr. A (sensibility 98%, specificity 94%, positive predictive value 90% and negative predictive value 94%) but only in 55% of cases in Gr. B (sensibility 55%, specificity 90%, positive predictive value 71% and negative predictive value 81%). Moreover, only 1 of the 4 in-stent restenoses has been detected (sensibility 25%, specificity 100%, positive predictive value 100% and negative predictive value 77%). Coronary angiography has detected a greater number of coronary stenoses than the 64-MSCT. 64-MSCT has demonstrated better accuracy in the study of coronary vessels wider than 2 mm, while its accuracy is lower for smaller vessels (diameter < 2.5 mm) and for the identification of in-stent restenosis, because there is a reduced image quality for these vessels and therefore a lower accuracy in the coronary stenosis detection. Nevertheless, 64-MSCT shows high accuracy and it can be considered a comparative but not a substitutive exam of the coronary angiography. Several technical limitations of the 64-MSCT are responsible of its lower accuracy versus the conventional coronary angiography, but solving these technical problems could give us a new non-invasive imaging technique for the study of coronary stents.

A Comparison of Dose-Response Models for the Parotid Gland in a Large Group of Head-and-Neck Cancer Patients

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

Houweling, Antonetta C., E-mail: A.Houweling@umcutrecht.n; Philippens, Marielle E.P.; Dijkema, Tim

2010-03-15

Purpose: The dose-response relationship of the parotid gland has been described most frequently using the Lyman-Kutcher-Burman model. However, various other normal tissue complication probability (NTCP) models exist. We evaluated in a large group of patients the value of six NTCP models that describe the parotid gland dose response 1 year after radiotherapy. Methods and Materials: A total of 347 patients with head-and-neck tumors were included in this prospective parotid gland dose-response study. The patients were treated with either conventional radiotherapy or intensity-modulated radiotherapy. Dose-volume histograms for the parotid glands were derived from three-dimensional dose calculations using computed tomography scans. Stimulatedmore » salivary flow rates were measured before and 1 year after radiotherapy. A threshold of 25% of the pretreatment flow rate was used to define a complication. The evaluated models included the Lyman-Kutcher-Burman model, the mean dose model, the relative seriality model, the critical volume model, the parallel functional subunit model, and the dose-threshold model. The goodness of fit (GOF) was determined by the deviance and a Monte Carlo hypothesis test. Ranking of the models was based on Akaike's information criterion (AIC). Results: None of the models was rejected based on the evaluation of the GOF. The mean dose model was ranked as the best model based on the AIC. The TD{sub 50} in these models was approximately 39 Gy. Conclusions: The mean dose model was preferred for describing the dose-response relationship of the parotid gland.« less

Evaluation of Larynx-Sparing Techniques With IMRT When Treating the Head and Neck

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

Webster, Gareth J.; Rowbottom, Carl G.; Ho, Kean F.

2008-10-01

Purpose: Concern exists that widespread implementation of whole-field intensity-modulated radiotherapy (IMRT) for the treatment of head-and-neck cancer has resulted in increased levels of dysphagia relative to those seen with conventional planning. Other investigators have suggested an alternative junctioned-IMRT (J-IMRT) method, which matches an IMRT plan to a centrally blocked neck field to restrict the laryngeal dose and reduce dysphagia. The effect on target coverage and sparing of organs at risk, including laryngeal sparing, in the optimization was evaluated and compared with that achieved using a J-IMRT technique. Methods and Materials: A total of 13 oropharyngeal cancer whole-field IMRT plans weremore » planned with and without including laryngeal sparing in the optimization. A comparison of the target coverage and sparing of organs at risk was made using the resulting dose-volume histograms and dose distribution. The nine plans with disease located superior to the level of the larynx were replanned using a series of J-IMRT techniques to compare the two laryngeal-sparing techniques. Results: An average mean larynx dose of 29.1 Gy was achieved if disease did not extend to the level of the larynx, with 38.8 Gy for disease extending inferiorly and close to the larynx (reduced from 46.2 and 47.7 Gy, respectively, without laryngeal sparing). Additional laryngeal sparing could be achieved with J-IMRT (mean dose 24.4 Gy), although often at the expense of significantly reduced coverage of the target volume and with no improvement to other areas of the IMRT plan. Conclusion: The benefits of J-IMRT can be achieved with whole-field IMRT if laryngeal sparing is incorporated into the class solution. Inclusion of laryngeal sparing had no effect on other parameters in the plan.« less

[Multispiral computed tomographic semiotics of laryngeal cancer].

PubMed

Vasil'ev, P V; Iudin, A L; Sdvizhkov, A M; Kozhanov, L G

2007-01-01

Multispiral computed tomography (MSCT) with intravenous bolus contrasting is a currently available method for radiodiagnosis of laryngeal cancer. MSCT is of much higher informative value in estimating the extent of a tumorous lesion than the traditional radiodiagnostic techniques: linear tomography, lateral X-ray study, roentgenoscopy and roentgenography of the laryngopharynx and esophagus with barium meal.

Imaging of the midpalatal suture in a porcine model: flat-panel volume computed tomography compared with multislice computed tomography.

PubMed

Hahn, Wolfram; Fricke-Zech, Susanne; Fialka-Fricke, Julia; Dullin, Christian; Zapf, Antonia; Gruber, Rudolf; Sennhenn-kirchner, Sabine; Kubein-Meesenburg, Dietmar; Sadat-Khonsari, Reza

2009-09-01

An investigation was conducted to compare the image quality of prototype flat-panel volume computed tomography (fpVCT) and multislice computed tomography (MSCT) of suture structures. Bone samples were taken from the midpalatal suture of 5 young (16 weeks) and 5 old (200 weeks) Sus scrofa domestica and fixed in formalin solution. An fpVCT prototype and an MSCT were used to obtain images of the specimens. The facial reformations were assessed by 4 observers using a 1 (excellent) to 5 (poor) rating scale for the weighted criteria visualization of the suture structure. A linear mixed model was used for statistical analysis. Results with P < .05 were considered to be statistically significant. The visualization of the suture of young specimens was significantly better than that of older animals (P < .001). The visualization of the suture with fpVCT was significantly better than that with MSCT (P < .001). Compared with MSCT, fpVCT produces superior results in the visualization of the midpalatal suture in a Sus scrofa domestica model.

Integrated beam orientation and scanning-spot optimization in intensity-modulated proton therapy for brain and unilateral head and neck tumors.

PubMed

Gu, Wenbo; O'Connor, Daniel; Nguyen, Dan; Yu, Victoria Y; Ruan, Dan; Dong, Lei; Sheng, Ke

2018-04-01

Intensity-Modulated Proton Therapy (IMPT) is the state-of-the-art method of delivering proton radiotherapy. Previous research has been mainly focused on optimization of scanning spots with manually selected beam angles. Due to the computational complexity, the potential benefit of simultaneously optimizing beam orientations and spot pattern could not be realized. In this study, we developed a novel integrated beam orientation optimization (BOO) and scanning-spot optimization algorithm for intensity-modulated proton therapy (IMPT). A brain chordoma and three unilateral head-and-neck patients with a maximal target size of 112.49 cm 3 were included in this study. A total number of 1162 noncoplanar candidate beams evenly distributed across 4π steradians were included in the optimization. For each candidate beam, the pencil-beam doses of all scanning spots covering the PTV and a margin were calculated. The beam angle selection and spot intensity optimization problem was formulated to include three terms: a dose fidelity term to penalize the deviation of PTV and OAR doses from ideal dose distribution; an L1-norm sparsity term to reduce the number of active spots and improve delivery efficiency; a group sparsity term to control the number of active beams between 2 and 4. For the group sparsity term, convex L2,1-norm and nonconvex L2,1/2-norm were tested. For the dose fidelity term, both quadratic function and linearized equivalent uniform dose (LEUD) cost function were implemented. The optimization problem was solved using the Fast Iterative Shrinkage-Thresholding Algorithm (FISTA). The IMPT BOO method was tested on three head-and-neck patients and one skull base chordoma patient. The results were compared with IMPT plans created using column generation selected beams or manually selected beams. The L2,1-norm plan selected spatially aggregated beams, indicating potential degeneracy using this norm. L2,1/2-norm was able to select spatially separated beams and achieve smaller deviation from the ideal dose. In the L2,1/2-norm plans, the [mean dose, maximum dose] of OAR were reduced by an average of [2.38%, 4.24%] and[2.32%, 3.76%] of the prescription dose for the quadratic and LEUD cost function, respectively, compared with the IMPT plan using manual beam selection while maintaining the same PTV coverage. The L2,1/2 group sparsity plans were dosimetrically superior to the column generation plans as well. Besides beam orientation selection, spot sparsification was observed. Generally, with the quadratic cost function, 30%~60% spots in the selected beams remained active. With the LEUD cost function, the percentages of active spots were in the range of 35%~85%.The BOO-IMPT run time was approximately 20 min. This work shows the first IMPT approach integrating noncoplanar BOO and scanning-spot optimization in a single mathematical framework. This method is computationally efficient, dosimetrically superior and produces delivery-friendly IMPT plans. © 2018 American Association of Physicists in Medicine.

Coronary risk stratification of patients undergoing surgery for valvular heart disease.

PubMed

Hasselbalch, Rasmus Bo; Engstrøm, Thomas; Pries-Heje, Mia; Heitmann, Merete; Pedersen, Frants; Schou, Morten; Mickley, Hans; Elming, Hanne; Steffensen, Rolf; Køber, Lars; Iversen, Kasper

2017-01-15

Multislice computed tomography (MSCT) is a non-invasive, less expensive, low-radiation alternative to coronary angiography (CAG) prior to valvular heart surgery. MSCT has a high negative predictive value for coronary artery disease (CAD) but previous studies of patients with valvular disease have shown that MSCT, as the primary evaluation technique, lead to re-evaluation with CAG in about a third of cases and it is therefore not recommended. If a subgroup of patients with low- to intermediate risk of CAD could be identified and examined with MSCT, it could be cost-effective, reduce radiation and the risk of complications associated with CAG. The study cohort was derived from a national registry of patients undergoing CAG prior to valvular heart surgery. Using logistic regression, we identified significant risk factors for CAD and developed a risk score (CT-valve score). The score was validated on a similar cohort of patients from another registry. The study cohort consisted of 2221 patients, 521 (23.5%) had CAD. The validation cohort consisted of 2575 patients, 771 (29.9%) had CAD. The identified risk factors were male sex, age, smoking, hyperlipidemia, hypertension, aortic valve disease, extracardiac arteriopathy, ejection fraction <30% and diabetes mellitus. CT-valve score could identify a third of the population with a risk about 10%. A score based on risk factors of CAD can identify patients that might benefit from using MSCT as a gatekeeper to CAG prior to heart valve surgery. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

SU-F-T-364: Monte Carlo-Dose Verification of Volumetric Modulated Arc Therapy Plans Using AAPM TG-119 Test Patterns

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

Onizuka, R; Araki, F; Ohno, T

2016-06-15

Purpose: To investigate the Monte Carlo (MC)-based dose verification for VMAT plans by a treatment planning system (TPS). Methods: The AAPM TG-119 test structure set was used for VMAT plans by the Pinnacle3 (convolution/superposition), using a Synergy radiation head of a 6 MV beam with the Agility MLC. The Synergy was simulated with the EGSnrc/BEAMnrc code, and VMAT dose distributions were calculated with the EGSnrc/DOSXYZnrc code by the same irradiation conditions as TPS. VMAT dose distributions of TPS and MC were compared with those of EBT3 film, by 2-D gamma analysis of ±3%/3 mm criteria with a threshold of 30%more » of prescribed doses. VMAT dose distributions between TPS and MC were also compared by DVHs and 3-D gamma analysis of ±3%/3 mm criteria with a threshold of 10%, and 3-D passing rates for PTVs and OARs were analyzed. Results: TPS dose distributions differed from those of film, especially for Head & neck. The dose difference between TPS and film results from calculation accuracy for complex motion of MLCs like tongue and groove effect. In contrast, MC dose distributions were in good agreement with those of film. This is because MC can model fully the MLC configuration and accurately reproduce the MLC motion between control points in VMAT plans. D95 of PTV for Prostate, Head & neck, C-shaped, and Multi Target was 97.2%, 98.1%, 101.6%, and 99.7% for TPS and 95.7%, 96.0%, 100.6%, and 99.1% for MC, respectively. Similarly, 3-D gamma passing rates of each PTV for TPS vs. MC were 100%, 89.5%, 99.7%, and 100%, respectively. 3-D passing rates of TPS reduced for complex VMAT fields like Head & neck because MLCs are not modeled completely for TPS. Conclusion: MC-calculated VMAT dose distributions is useful for the 3-D dose verification of VMAT plans by TPS.« less

Effect of patient setup errors on simultaneously integrated boost head and neck IMRT treatment plans

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

Siebers, Jeffrey V.; Keall, Paul J.; Wu Qiuwen

2005-10-01

Purpose: The purpose of this study is to determine dose delivery errors that could result from random and systematic setup errors for head-and-neck patients treated using the simultaneous integrated boost (SIB)-intensity-modulated radiation therapy (IMRT) technique. Methods and Materials: Twenty-four patients who participated in an intramural Phase I/II parotid-sparing IMRT dose-escalation protocol using the SIB treatment technique had their dose distributions reevaluated to assess the impact of random and systematic setup errors. The dosimetric effect of random setup error was simulated by convolving the two-dimensional fluence distribution of each beam with the random setup error probability density distribution. Random setup errorsmore » of {sigma} = 1, 3, and 5 mm were simulated. Systematic setup errors were simulated by randomly shifting the patient isocenter along each of the three Cartesian axes, with each shift selected from a normal distribution. Systematic setup error distributions with {sigma} = 1.5 and 3.0 mm along each axis were simulated. Combined systematic and random setup errors were simulated for {sigma} = {sigma} = 1.5 and 3.0 mm along each axis. For each dose calculation, the gross tumor volume (GTV) received by 98% of the volume (D{sub 98}), clinical target volume (CTV) D{sub 90}, nodes D{sub 90}, cord D{sub 2}, and parotid D{sub 50} and parotid mean dose were evaluated with respect to the plan used for treatment for the structure dose and for an effective planning target volume (PTV) with a 3-mm margin. Results: Simultaneous integrated boost-IMRT head-and-neck treatment plans were found to be less sensitive to random setup errors than to systematic setup errors. For random-only errors, errors exceeded 3% only when the random setup error {sigma} exceeded 3 mm. Simulated systematic setup errors with {sigma} = 1.5 mm resulted in approximately 10% of plan having more than a 3% dose error, whereas a {sigma} = 3.0 mm resulted in half of the plans having more than a 3% dose error and 28% with a 5% dose error. Combined random and systematic dose errors with {sigma} = {sigma} = 3.0 mm resulted in more than 50% of plans having at least a 3% dose error and 38% of the plans having at least a 5% dose error. Evaluation with respect to a 3-mm expanded PTV reduced the observed dose deviations greater than 5% for the {sigma} = {sigma} = 3.0 mm simulations to 5.4% of the plans simulated. Conclusions: Head-and-neck SIB-IMRT dosimetric accuracy would benefit from methods to reduce patient systematic setup errors. When GTV, CTV, or nodal volumes are used for dose evaluation, plans simulated including the effects of random and systematic errors deviate substantially from the nominal plan. The use of PTVs for dose evaluation in the nominal plan improves agreement with evaluated GTV, CTV, and nodal dose values under simulated setup errors. PTV concepts should be used for SIB-IMRT head-and-neck squamous cell carcinoma patients, although the size of the margins may be less than those used with three-dimensional conformal radiation therapy.« less

Re-irradiation Using Intensity-modulated Radiotherapy for Recurrent and Second Primary Head and Neck Cancer.

PubMed

Choi, Seo Hee; Chang, Jee Suk; Choi, Jinhyun; Park, So Hyun; Keum, Ki Chang; Park, Kyung Ran; Lee, Chang Geol

2018-05-01

Information on re-irradiation (re-RT) for recurrent and second primary head and neck cancer is limited. Herein, a description of our long-term experience of re-RT for previously irradiated head and neck cancer is provided. A retrospective review was performed for 73 consecutive patients re-irradiated for head and neck cancer between 2006 and 2015. Re-RT targets encompassed only the recurrent gross tumor and had tight margins (5-10 mm). Salvage surgery was performed on 28 (38%) patients before re-RT and 53 (73%) patients received chemotherapy concurrent with re-RT. The median interval between initial and re-RT was 31 months and the median cumulative dose of the two irradiations was 126 Gy (biologically equivalent to 2 Gy fractionation). With a median survival of 33 months, locoregional recurrence after re-RT developed in 37 patients (51%; 25 infield, 12 outfield). In multivariate analysis, higher re-RT dose (≥66 Gy), longer time interval (>2 years), and use of concurrent chemotherapy were associated with improved locoregional recurrence-free survival (all p<0.05). Additionally, performance status, additional surgical resection, and longer interval were associated with better overall survival (p=0.006, 0.021, 0.004, respectively). Clinically significant acute and late toxicities occurred in 14% and 22% of evaluable patients, but no grade 5 toxicity was observed. Moderate safety and acceptable toxicity was found after re-RT using tight margins, sufficient radiation dose, and daily image guidance. Encouraging local control and survival were obtained, similar to historical data using 1-2 cm margins. Copyright© 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

Reirradiation of head and neck cancer: Long-term disease control and toxicity.

PubMed

Bots, Wouter T C; van den Bosch, Sven; Zwijnenburg, Ellen M; Dijkema, Tim; van den Broek, Guido B; Weijs, Willem L J; Verhoef, Lia C G; Kaanders, Johannes H A M

2017-06-01

The purpose of this study was to report long-term disease control and late radiation toxicity for patients reirradiated for head and neck cancer. We conducted a retrospective analysis of 137 patients reirradiated with a prescribed dose ≥45 Gy between 1986 and 2013 for a recurrent or second primary malignancy. Endpoints were locoregional control, overall survival (OS), and grade ≥4 late complications according to European Organization for Research and Treatment of Cancer (EORTC)/Radiation Therapy Oncology Group (RTOG) criteria. Five-year locoregional control rates were 46% for patients reirradiated postoperatively versus 20% for patients who underwent reirradiation as the primary treatment (p < .05). Sixteen cases of serious (grade ≥4) late toxicity were seen in 11 patients (actuarial 28% at 5 years). In patients reirradiated with intensity-modulated radiotherapy (IMRT), a borderline improved locoregional control was observed (49% vs 36%; p = .07), whereas late complication rates did not differ. Reirradiation should be considered for patients with a recurrent or second primary head and neck cancer, especially postoperatively, if indicated. © 2017 Wiley Periodicals, Inc. Head Neck 39: 1122-1130, 2017. © 2017 The Authors Head & Neck Published by Wiley Periodicals, Inc.

Quantitative assessment of the accuracy of dose calculation using pencil beam and Monte Carlo algorithms and requirements for clinical quality assurance

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

Ali, Imad, E-mail: iali@ouhsc.edu; Ahmad, Salahuddin

2013-10-01

To compare the doses calculated using the BrainLAB pencil beam (PB) and Monte Carlo (MC) algorithms for tumors located in various sites including the lung and evaluate quality assurance procedures required for the verification of the accuracy of dose calculation. The dose-calculation accuracy of PB and MC was also assessed quantitatively with measurement using ionization chamber and Gafchromic films placed in solid water and heterogeneous phantoms. The dose was calculated using PB convolution and MC algorithms in the iPlan treatment planning system from BrainLAB. The dose calculation was performed on the patient's computed tomography images with lesions in various treatmentmore » sites including 5 lungs, 5 prostates, 4 brains, 2 head and necks, and 2 paraspinal tissues. A combination of conventional, conformal, and intensity-modulated radiation therapy plans was used in dose calculation. The leaf sequence from intensity-modulated radiation therapy plans or beam shapes from conformal plans and monitor units and other planning parameters calculated by the PB were identical for calculating dose with MC. Heterogeneity correction was considered in both PB and MC dose calculations. Dose-volume parameters such as V95 (volume covered by 95% of prescription dose), dose distributions, and gamma analysis were used to evaluate the calculated dose by PB and MC. The measured doses by ionization chamber and EBT GAFCHROMIC film in solid water and heterogeneous phantoms were used to quantitatively asses the accuracy of dose calculated by PB and MC. The dose-volume histograms and dose distributions calculated by PB and MC in the brain, prostate, paraspinal, and head and neck were in good agreement with one another (within 5%) and provided acceptable planning target volume coverage. However, dose distributions of the patients with lung cancer had large discrepancies. For a plan optimized with PB, the dose coverage was shown as clinically acceptable, whereas in reality, the MC showed a systematic lack of dose coverage. The dose calculated by PB for lung tumors was overestimated by up to 40%. An interesting feature that was observed is that despite large discrepancies in dose-volume histogram coverage of the planning target volume between PB and MC, the point doses at the isocenter (center of the lesions) calculated by both algorithms were within 7% even for lung cases. The dose distributions measured with EBT GAFCHROMIC films in heterogeneous phantoms showed large discrepancies of nearly 15% lower than PB at interfaces between heterogeneous media, where these lower doses measured by the film were in agreement with those by MC. The doses (V95) calculated by MC and PB agreed within 5% for treatment sites with small tissue heterogeneities such as the prostate, brain, head and neck, and paraspinal tumors. Considerable discrepancies, up to 40%, were observed in the dose-volume coverage between MC and PB in lung tumors, which may affect clinical outcomes. The discrepancies between MC and PB increased for 15 MV compared with 6 MV indicating the importance of implementation of accurate clinical treatment planning such as MC. The comparison of point doses is not representative of the discrepancies in dose coverage and might be misleading in evaluating the accuracy of dose calculation between PB and MC. Thus, the clinical quality assurance procedures required to verify the accuracy of dose calculation using PB and MC need to consider measurements of 2- and 3-dimensional dose distributions rather than a single point measurement using heterogeneous phantoms instead of homogenous water-equivalent phantoms.« less

SU-E-T-32: A Feasibility Study of Independent Dose Verification for IMAT

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

Kamima, T; Takahashi, R; Sato, Y

2015-06-15

Purpose: To assess the feasibility of the independent dose verification (Indp) for intensity modulated arc therapy (IMAT). Methods: An independent dose calculation software program (Simple MU Analysis, Triangle Products, JP) was used in this study, which can compute the radiological path length from the surface to the reference point for each control point using patient’s CT image dataset and the MLC aperture shape was simultaneously modeled in reference to the information of MLC from DICOM-RT plan. Dose calculation was performed using a modified Clarkson method considering MLC transmission and dosimetric leaf gap. In this study, a retrospective analysis was conductedmore » in which IMAT plans from 120 patients of the two sites (prostate / head and neck) from four institutes were retrospectively analyzed to compare the Indp to the TPS using patient CT images. In addition, an ion-chamber measurement was performed to verify the accuracy of the TPS and the Indp in water-equivalent phantom. Results: The agreements between the Indp and the TPS (mean±1SD) were −0.8±2.4% and −1.3±3.8% for the regions of prostate and head and neck, respectively. The measurement comparison showed similar results (−0.8±1.6% and 0.1±4.6% for prostate and head and neck). The variation was larger in the head and neck because the number of the segments was increased that the reference point was under the MLC and the modified Clarkson method cannot consider the smooth falloff of the leaf penumbra. Conclusion: The independent verification program would be practical and effective for secondary check for IMAT with the sufficient accuracy in the measurement and CT-based calculation. The accuracy would be improved if considering the falloff of the leaf penumbra.« less

Into the decomposed body-forensic digital autopsy using multislice-computed tomography.

PubMed

Thali, M J; Yen, K; Schweitzer, W; Vock, P; Ozdoba, C; Dirnhofer, R

2003-07-08

It is impossible to obtain a representative anatomical documentation of an entire body using classical X-ray methods, they subsume three-dimensional bodies into a two-dimensional level. We used the novel multislice-computed tomography (MSCT) technique in order to evaluate a case of homicide with putrefaction of the corpse before performing a classical forensic autopsy. This non-invasive method showed gaseous distension of the decomposing organs and tissues in detail as well as a complex fracture of the calvarium. MSCT also proved useful in screening for foreign matter in decomposing bodies, and full-body scanning took only a few minutes. In conclusion, we believe postmortem MSCT imaging is an excellent vizualisation tool with great potential for forensic documentation and evaluation of decomposed bodies.

Evaluation of a commercial automatic treatment planning system for prostate cancers.

PubMed

Nawa, Kanabu; Haga, Akihiro; Nomoto, Akihiro; Sarmiento, Raniel A; Shiraishi, Kenshiro; Yamashita, Hideomi; Nakagawa, Keiichi

2017-01-01

Recent developments in Radiation Oncology treatment planning have led to the development of software packages that facilitate automated intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) planning. Such solutions include site-specific modules, plan library methods, and algorithm-based methods. In this study, the plan quality for prostate cancer generated by the Auto-Planning module of the Pinnacle 3 radiation therapy treatment planning system (v9.10, Fitchburg, WI) is retrospectively evaluated. The Auto-Planning module of Pinnacle 3 uses a progressive optimization algorithm. Twenty-three prostate cancer cases, which had previously been planned and treated without lymph node irradiation, were replanned using the Auto-Planning module. Dose distributions were statistically compared with those of manual planning by the paired t-test at 5% significance level. Auto-Planning was performed without any manual intervention. Planning target volume (PTV) dose and dose to rectum were comparable between Auto-Planning and manual planning. The former, however, significantly reduced the dose to the bladder and femurs. Regression analysis was performed to examine the correlation between volume overlap between bladder and PTV divided by the total bladder volume and resultant V70. The findings showed that manual planning typically exhibits a logistic way for dose constraint, whereas Auto-Planning shows a more linear tendency. By calculating the Akaike information criterion (AIC) to validate the statistical model, a reduction of interoperator variation in Auto-Planning was shown. We showed that, for prostate cancer, the Auto-Planning module provided plans that are better than or comparable with those of manual planning. By comparing our results with those previously reported for head and neck cancer treatment, we recommend the homogeneous plan quality generated by the Auto-Planning module, which exhibits less dependence on anatomic complexity. Copyright © 2017 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

Will weight loss cause significant dosimetric changes of target volumes and organs at risk in nasopharyngeal carcinoma treated with intensity-modulated radiation therapy?

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

Chen, Chuanben; Fei, Zhaodong; Chen, Lisha

This study aimed to quantify dosimetric effects of weight loss for nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiation therapy (IMRT). Overall, 25 patients with NPC treated with IMRT were enrolled. We simulated weight loss during IMRT on the computer. Weight loss model was based on the planning computed tomography (CT) images. The original external contour of head and neck was labeled plan 0, and its volume was regarded as pretreatment normal weight. We shrank the external contour with different margins (2, 3, and 5 mm) and generated new external contours of head and neck. The volumes of reconstructed external contoursmore » were regarded as weight during radiotherapy. After recontouring outlines, the initial treatment plan was mapped to the redefined CT scans with the same beam configurations, yielding new plans. The computer model represented a theoretical proportional weight loss of 3.4% to 13.7% during the course of IMRT. The dose delivered to the planning target volume (PTV) of primary gross tumor volume and clinical target volume significantly increased by 1.9% to 2.9% and 1.8% to 2.9% because of weight loss, respectively. The dose to the PTV of gross tumor volume of lymph nodes fluctuated from −2.0% to 1.0%. The dose to the brain stem and the spinal cord was increased (p < 0.001), whereas the dose to the parotid gland was decreased (p < 0.001). Weight loss may lead to significant dosimetric change during IMRT. Repeated scanning and replanning for patients with NPC with an obvious weight loss may be necessary.« less

Dentalmaps: Automatic Dental Delineation for Radiotherapy Planning in Head-and-Neck Cancer

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

Thariat, Juliette, E-mail: jthariat@hotmail.com; Ramus, Liliane; INRIA

Purpose: To propose an automatic atlas-based segmentation framework of the dental structures, called Dentalmaps, and to assess its accuracy and relevance to guide dental care in the context of intensity-modulated radiotherapy. Methods and Materials: A multi-atlas-based segmentation, less sensitive to artifacts than previously published head-and-neck segmentation methods, was used. The manual segmentations of a 21-patient database were first deformed onto the query using nonlinear registrations with the training images and then fused to estimate the consensus segmentation of the query. Results: The framework was evaluated with a leave-one-out protocol. The maximum doses estimated using manual contours were considered as groundmore » truth and compared with the maximum doses estimated using automatic contours. The dose estimation error was within 2-Gy accuracy in 75% of cases (with a median of 0.9 Gy), whereas it was within 2-Gy accuracy in 30% of cases only with the visual estimation method without any contour, which is the routine practice procedure. Conclusions: Dose estimates using this framework were more accurate than visual estimates without dental contour. Dentalmaps represents a useful documentation and communication tool between radiation oncologists and dentists in routine practice. Prospective multicenter assessment is underway on patients extrinsic to the database.« less

Validation of a track repeating algorithm for intensity modulated proton therapy: clinical cases study

NASA Astrophysics Data System (ADS)

Yepes, Pablo P.; Eley, John G.; Liu, Amy; Mirkovic, Dragan; Randeniya, Sharmalee; Titt, Uwe; Mohan, Radhe

2016-04-01

Monte Carlo (MC) methods are acknowledged as the most accurate technique to calculate dose distributions. However, due its lengthy calculation times, they are difficult to utilize in the clinic or for large retrospective studies. Track-repeating algorithms, based on MC-generated particle track data in water, accelerate dose calculations substantially, while essentially preserving the accuracy of MC. In this study, we present the validation of an efficient dose calculation algorithm for intensity modulated proton therapy, the fast dose calculator (FDC), based on a track-repeating technique. We validated the FDC algorithm for 23 patients, which included 7 brain, 6 head-and-neck, 5 lung, 1 spine, 1 pelvis and 3 prostate cases. For validation, we compared FDC-generated dose distributions with those from a full-fledged Monte Carlo based on GEANT4 (G4). We compared dose-volume-histograms, 3D-gamma-indices and analyzed a series of dosimetric indices. More than 99% of the voxels in the voxelized phantoms describing the patients have a gamma-index smaller than unity for the 2%/2 mm criteria. In addition the difference relative to the prescribed dose between the dosimetric indices calculated with FDC and G4 is less than 1%. FDC reduces the calculation times from 5 ms per proton to around 5 μs.

Comparison of linear and nonlinear programming approaches for "worst case dose" and "minmax" robust optimization of intensity-modulated proton therapy dose distributions.

PubMed

Zaghian, Maryam; Cao, Wenhua; Liu, Wei; Kardar, Laleh; Randeniya, Sharmalee; Mohan, Radhe; Lim, Gino

2017-03-01

Robust optimization of intensity-modulated proton therapy (IMPT) takes uncertainties into account during spot weight optimization and leads to dose distributions that are resilient to uncertainties. Previous studies demonstrated benefits of linear programming (LP) for IMPT in terms of delivery efficiency by considerably reducing the number of spots required for the same quality of plans. However, a reduction in the number of spots may lead to loss of robustness. The purpose of this study was to evaluate and compare the performance in terms of plan quality and robustness of two robust optimization approaches using LP and nonlinear programming (NLP) models. The so-called "worst case dose" and "minmax" robust optimization approaches and conventional planning target volume (PTV)-based optimization approach were applied to designing IMPT plans for five patients: two with prostate cancer, one with skull-based cancer, and two with head and neck cancer. For each approach, both LP and NLP models were used. Thus, for each case, six sets of IMPT plans were generated and assessed: LP-PTV-based, NLP-PTV-based, LP-worst case dose, NLP-worst case dose, LP-minmax, and NLP-minmax. The four robust optimization methods behaved differently from patient to patient, and no method emerged as superior to the others in terms of nominal plan quality and robustness against uncertainties. The plans generated using LP-based robust optimization were more robust regarding patient setup and range uncertainties than were those generated using NLP-based robust optimization for the prostate cancer patients. However, the robustness of plans generated using NLP-based methods was superior for the skull-based and head and neck cancer patients. Overall, LP-based methods were suitable for the less challenging cancer cases in which all uncertainty scenarios were able to satisfy tight dose constraints, while NLP performed better in more difficult cases in which most uncertainty scenarios were hard to meet tight dose limits. For robust optimization, the worst case dose approach was less sensitive to uncertainties than was the minmax approach for the prostate and skull-based cancer patients, whereas the minmax approach was superior for the head and neck cancer patients. The robustness of the IMPT plans was remarkably better after robust optimization than after PTV-based optimization, and the NLP-PTV-based optimization outperformed the LP-PTV-based optimization regarding robustness of clinical target volume coverage. In addition, plans generated using LP-based methods had notably fewer scanning spots than did those generated using NLP-based methods. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

Digital forensic osteology--possibilities in cooperation with the Virtopsy project.

PubMed

Verhoff, Marcel A; Ramsthaler, Frank; Krähahn, Jonathan; Deml, Ulf; Gille, Ralf J; Grabherr, Silke; Thali, Michael J; Kreutz, Kerstin

2008-01-30

The present study was carried out to check whether classic osteometric parameters can be determined from the 3D reconstructions of MSCT (multislice computed tomography) scans acquired in the context of the Virtopsy project. To this end, four isolated and macerated skulls were examined by six examiners. First the skulls were conventionally (manually) measured using 32 internationally accepted linear measurements. Then the skulls were scanned by the use of MSCT with slice thicknesses of 1.25 mm and 0.63 mm, and the 33 measurements were virtually determined on the digital 3D reconstructions of the skulls. The results of the traditional and the digital measurements were compared for each examiner to figure out variations. Furthermore, several parameters were measured on the cranium and postcranium during an autopsy and compared to the values that had been measured on a 3D reconstruction from a previously acquired postmortem MSCT scan. The results indicate that equivalent osteometric values can be obtained from digital 3D reconstructions from MSCT scans using a slice thickness of 1.25 mm, and from conventional manual examinations. The measurements taken from a corpse during an autopsy could also be validated with the methods used for the digital 3D reconstructions in the context of the Virtopsy project. Future aims are the assessment and biostatistical evaluation in respect to sex, age and stature of all data sets stored in the Virtopsy project so far, as well as of future data sets. Furthermore, a definition of new parameters, only measurable with the aid of MSCT data would be conceivable.

Rapid fusion of 2D X-ray fluoroscopy with 3D multislice CT for image-guided electrophysiology procedures

NASA Astrophysics Data System (ADS)

Zagorchev, Lyubomir; Manzke, Robert; Cury, Ricardo; Reddy, Vivek Y.; Chan, Raymond C.

2007-03-01

Interventional cardiac electrophysiology (EP) procedures are typically performed under X-ray fluoroscopy for visualizing catheters and EP devices relative to other highly-attenuating structures such as the thoracic spine and ribs. These projections do not however contain information about soft-tissue anatomy and there is a recognized need for fusion of conventional fluoroscopy with pre-operatively acquired cardiac multislice computed tomography (MSCT) volumes. Rapid 2D-3D integration in this application would allow for real-time visualization of all catheters present within the thorax in relation to the cardiovascular anatomy visible in MSCT. We present a method for rapid fusion of 2D X-ray fluoroscopy with 3DMSCT that can facilitate EP mapping and interventional procedures by reducing the need for intra-operative contrast injections to visualize heart chambers and specialized systems to track catheters within the cardiovascular anatomy. We use hardware-accelerated ray-casting to compute digitally reconstructed radiographs (DRRs) from the MSCT volume and iteratively optimize the rigid-body pose of the volumetric data to maximize the similarity between the MSCT-derived DRR and the intra-operative X-ray projection data.

A comparison of intensity modulated x-ray therapy to intensity modulated proton therapy for the delivery of non-uniform dose distributions

NASA Astrophysics Data System (ADS)

Flynn, Ryan

2007-12-01

The distribution of biological characteristics such as clonogen density, proliferation, and hypoxia throughout tumors is generally non-uniform, therefore it follows that the optimal dose prescriptions should also be non-uniform and tumor-specific. Advances in intensity modulated x-ray therapy (IMXT) technology have made the delivery of custom-made non-uniform dose distributions possible in practice. Intensity modulated proton therapy (IMPT) has the potential to deliver non-uniform dose distributions as well, while significantly reducing normal tissue and organ at risk dose relative to IMXT. In this work, a specialized treatment planning system was developed for the purpose of optimizing and comparing biologically based IMXT and IMPT plans. The IMXT systems of step-and-shoot (IMXT-SAS) and helical tomotherapy (IMXT-HT) and the IMPT systems of intensity modulated spot scanning (IMPT-SS) and distal gradient tracking (IMPT-DGT), were simulated. A thorough phantom study was conducted in which several subvolumes, which were contained within a base tumor region, were boosted or avoided with IMXT and IMPT. Different boosting situations were simulated by varying the size, proximity, and the doses prescribed to the subvolumes, and the size of the phantom. IMXT and IMPT were also compared for a whole brain radiation therapy (WBRT) case, in which a brain metastasis was simultaneously boosted and the hippocampus was avoided. Finally, IMXT and IMPT dose distributions were compared for the case of non-uniform dose prescription in a head and neck cancer patient that was based on PET imaging with the Cu(II)-diacetyl-bis(N4-methylthiosemicarbazone (Cu-ATSM) hypoxia marker. The non-uniform dose distributions within the tumor region were comparable for IMXT and IMPT. IMPT, however, was capable of delivering the same non-uniform dose distributions within a tumor using a 180° arc as for a full 360° rotation, which resulted in the reduction of normal tissue integral dose by a factor of up to three relative to IMXT, and the complete sparing of organs at risk distal to the tumor region.

Dose reduction potential of iterative reconstruction algorithms in neck CTA-a simulation study.

PubMed

Ellmann, Stephan; Kammerer, Ferdinand; Allmendinger, Thomas; Brand, Michael; Janka, Rolf; Hammon, Matthias; Lell, Michael M; Uder, Michael; Kramer, Manuel

2016-10-01

This study aimed to determine the degree of radiation dose reduction in neck CT angiography (CTA) achievable with Sinogram-affirmed iterative reconstruction (SAFIRE) algorithms. 10 consecutive patients scheduled for neck CTA were included in this study. CTA images of the external carotid arteries either were reconstructed with filtered back projection (FBP) at full radiation dose level or underwent simulated dose reduction by proprietary reconstruction software. The dose-reduced images were reconstructed using either SAFIRE 3 or SAFIRE 5 and compared with full-dose FBP images in terms of vessel definition. 5 observers performed a total of 3000 pairwise comparisons. SAFIRE allowed substantial radiation dose reductions in neck CTA while maintaining vessel definition. The possible levels of radiation dose reduction ranged from approximately 34 to approximately 90% and depended on the SAFIRE algorithm strength and the size of the vessel of interest. In general, larger vessels permitted higher degrees of radiation dose reduction, especially with higher SAFIRE strength levels. With small vessels, the superiority of SAFIRE 5 over SAFIRE 3 was lost. Neck CTA can be performed with substantially less radiation dose when SAFIRE is applied. The exact degree of radiation dose reduction should be adapted to the clinical question, in particular to the smallest vessel needing excellent definition.

IMRT delivers lower radiation doses to dental structures than 3DRT in head and neck cancer patients.

PubMed

Fregnani, Eduardo Rodrigues; Parahyba, Cláudia Joffily; Morais-Faria, Karina; Fonseca, Felipe Paiva; Ramos, Pedro Augusto Mendes; de Moraes, Fábio Yone; da Conceição Vasconcelos, Karina Gondim Moutinho; Menegussi, Gisela; Santos-Silva, Alan Roger; Brandão, Thais B

2016-09-07

Radiotherapy (RT) is frequently used in the treatment of head and neck cancer, but different side-effects are frequently reported, including a higher frequency of radiation-related caries, what may be consequence of direct radiation to dental tissue. The intensity-modulated radiotherapy (IMRT) was developed to improve tumor control and decrease patient's morbidity by delivering radiation beams only to tumor shapes and sparing normal tissue. However, teeth are usually not included in IMRT plannings and the real efficacy of IMRT in the dental context has not been addressed. Therefore, the aim of this study is to assess whether IMRT delivers lower radiation doses to dental structures than conformal 3D radiotherapy (3DRT). Radiation dose delivery to dental structures of 80 patients treated for head and neck cancers (oral cavity, tongue, nasopharynx and oropharynx) with IMRT (40 patients) and 3DRT (40 patients) were assessed by individually contouring tooth crowns on patients' treatment plans. Clinicopathological data were retrieved from patients' medical files. The average dose of radiation to teeth delivered by IMRT was significantly lower than with 3DRT (p = 0.007); however, only patients affected by nasopharynx and oral cavity cancers demonstrated significantly lower doses with IMRT (p = 0.012 and p = 0.011, respectively). Molars received more radiation with both 3DRT and IMRT, but the latter delivered significantly lower radiation in this group of teeth (p < 0.001), whereas no significant difference was found for the other dental groups. Maxillary teeth received lower doses than mandibular teeth, but only IMRT delivered significantly lower doses (p = 0.011 and p = 0.003). Ipsilateral teeth received higher doses than contralateral teeth with both techniques and IMRT delivered significantly lower radiation than 3DRT for contralateral dental structures (p < 0.001). IMRT delivered lower radiation doses to teeth than 3DRT, but only for some groups of patients and teeth, suggesting that this decrease was more likely due to the protection of other high risk organs, and was not enough to remove teeth from the zone of high risk for radiogenic disturbance (>30Gy).

Head-and-neck IMRT treatments assessed with a Monte Carlo dose calculation engine.

PubMed

Seco, J; Adams, E; Bidmead, M; Partridge, M; Verhaegen, F

2005-03-07

IMRT is frequently used in the head-and-neck region, which contains materials of widely differing densities (soft tissue, bone, air-cavities). Conventional methods of dose computation for these complex, inhomogeneous IMRT cases involve significant approximations. In the present work, a methodology for the development, commissioning and implementation of a Monte Carlo (MC) dose calculation engine for intensity modulated radiotherapy (MC-IMRT) is proposed which can be used by radiotherapy centres interested in developing MC-IMRT capabilities for research or clinical evaluations. The method proposes three levels for developing, commissioning and maintaining a MC-IMRT dose calculation engine: (a) development of a MC model of the linear accelerator, (b) validation of MC model for IMRT and (c) periodic quality assurance (QA) of the MC-IMRT system. The first step, level (a), in developing an MC-IMRT system is to build a model of the linac that correctly predicts standard open field measurements for percentage depth-dose and off-axis ratios. Validation of MC-IMRT, level (b), can be performed in a rando phantom and in a homogeneous water equivalent phantom. Ultimately, periodic quality assurance of the MC-IMRT system is needed to verify the MC-IMRT dose calculation system, level (c). Once the MC-IMRT dose calculation system is commissioned it can be applied to more complex clinical IMRT treatments. The MC-IMRT system implemented at the Royal Marsden Hospital was used for IMRT calculations for a patient undergoing treatment for primary disease with nodal involvement in the head-and-neck region (primary treated to 65 Gy and nodes to 54 Gy), while sparing the spinal cord, brain stem and parotid glands. Preliminary MC results predict a decrease of approximately 1-2 Gy in the median dose of both the primary tumour and nodal volumes (compared with both pencil beam and collapsed cone). This is possibly due to the large air-cavity (the larynx of the patient) situated in the centre of the primary PTV and the approximations present in the dose calculation.

Quantification of residual dose estimation error on log file-based patient dose calculation.

PubMed

Katsuta, Yoshiyuki; Kadoya, Noriyuki; Fujita, Yukio; Shimizu, Eiji; Matsunaga, Kenichi; Matsushita, Haruo; Majima, Kazuhiro; Jingu, Keiichi

2016-05-01

The log file-based patient dose estimation includes a residual dose estimation error caused by leaf miscalibration, which cannot be reflected on the estimated dose. The purpose of this study is to determine this residual dose estimation error. Modified log files for seven head-and-neck and prostate volumetric modulated arc therapy (VMAT) plans simulating leaf miscalibration were generated by shifting both leaf banks (systematic leaf gap errors: ±2.0, ±1.0, and ±0.5mm in opposite directions and systematic leaf shifts: ±1.0mm in the same direction) using MATLAB-based (MathWorks, Natick, MA) in-house software. The generated modified and non-modified log files were imported back into the treatment planning system and recalculated. Subsequently, the generalized equivalent uniform dose (gEUD) was quantified for the definition of the planning target volume (PTV) and organs at risks. For MLC leaves calibrated within ±0.5mm, the quantified residual dose estimation errors that obtained from the slope of the linear regression of gEUD changes between non- and modified log file doses per leaf gap are in head-and-neck plans 1.32±0.27% and 0.82±0.17Gy for PTV and spinal cord, respectively, and in prostate plans 1.22±0.36%, 0.95±0.14Gy, and 0.45±0.08Gy for PTV, rectum, and bladder, respectively. In this work, we determine the residual dose estimation errors for VMAT delivery using the log file-based patient dose calculation according to the MLC calibration accuracy. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

[Feasibility and short-term efficacy of simplified intensity-modulated radiotherapy and concurrent chemotherapy for neck and upper thoracic esophageal carcinoma].

PubMed

Zhu, Wei-Guo; Yu, Chang-Hua; Han, Ji-Hua; Li, Tao; Zhou, Xi-Lei; Tao, Guang-Zhou

2009-12-01

For neck and upper thoracic esophageal carcinoma, three dimensional conformal radiation therapy (3D-CRT) does not necessarily meet all clinical requirements while intensity modulated radiation therapy (IMRT) may take up a lot of labour power and material resources. This study was to explore the feasibility of simplified IMPT(sIMRT) and concurrent chemotherapy for neck and upper thoracic esophageal carcinoma, and to investigate the acute toxicities and short-term efficacy of this treatment modality. sIMRT plans were designed for 30 patients with neck and upper thoracic esophageal carcinoma. Two target volumes were defined: PTV1, which was designed to irradiate to 64 Gy (2.13 Gy x 30 fractions); PTV2, which was given to 54 Gy (1.8 Gy x 30). The sIMRT plan included five equiangular coplanar beams. All patients concurrently received DDP+5-FU regimen with radiotherapy on d1-5 and d29-33. Chemotherapy was repeated for two cycles 28 days after radiotherapy. The treatment was completed for all patients within 6 weeks, and only one patient had Grade 3 acute bronchitis. The complete response (CR) rate was 90.0% (27/30) and the partial response (PR) rate 10.0% (3/30). Overall response was 100% for esophageal lesions and the CR rate 76.5% (13/17). The PR rate was 23.5% (4/17) in lymph node lesions. The major toxicities observed were Grades I-II leukocytopenia. sIMRT can generate desirable dose distribution for neck and upper thoracic esophageal carcinoma, which is similar to sophisticated IMRT but obviously better than 3D-CRT. The short-term efficacy of sIMRT is satisfactory and its acute toxicities are tolerable.

Parotid gland sparing IMRT for head and neck cancer improves xerostomia related quality of life

PubMed Central

van Rij, CM; Oughlane-Heemsbergen, WD; Ackerstaff, AH; Lamers, EA; Balm, AJM; Rasch, CRN

2008-01-01

Background and purpose To assess the impact of intensity modulated radiotherapy (IMRT) versus conventional radiation on late xerostomia and Quality of Life aspects in head and neck cancer patients. Patients and nethods Questionnaires on xerostomia in rest and during meals were sent to all patients treated between January 1999 and December 2003 with a T1-4, N0-2 M0 head and neck cancer, with parotid gland sparing IMRT or conventional bilateral neck irradiation to a dose of at least 60 Gy, who were progression free and had no disseminated disease (n = 192). Overall response was 85% (n = 163); 97% in the IMRT group (n = 75) and 77% in the control group (n = 88) the median follow-up was 2.6 years. The prevalence of complaints was compared between the two groups, correcting for all relevant factors at multivariate ordinal regression analysis. Results Patients treated with IMRT reported significantly less difficulty transporting and swallowing their food and needed less water for a dry mouth during day, night and meals. They also experienced fewer problems with speech and eating in public. Laryngeal cancer patients in general had fewer complaints than oropharynx cancer patients but both groups benefited from IMRT. Within the IMRT group the xerostomia scores were better for those patients with a mean parotid dose to the "spared" parotid below 26 Gy. Conclusion Parotid gland sparing IMRT for head and neck cancer patients improves xerostomia related quality of life compared to conventional radiation both in rest and during meals. Laryngeal cancer patients had fewer complaints but benefited equally compared to oropharyngeal cancer patients from IMRT. PMID:19068126

Measuring quality of life in patients with head and neck cancer: Update of the EORTC QLQ-H&N Module, Phase III.

PubMed

Singer, Susanne; Araújo, Cláudia; Arraras, Juan Ignacio; Baumann, Ingo; Boehm, Andreas; Brokstad Herlofson, Bente; Castro Silva, Joaquim; Chie, Wei-Chu; Fisher, Sheila; Guntinas-Lichius, Orlando; Hammerlid, Eva; Irarrázaval, María Elisa; Jensen Hjermstad, Marianne; Jensen, Kenneth; Kiyota, Naomi; Licitra, Lisa; Nicolatou-Galitis, Ourania; Pinto, Monica; Santos, Marcos; Schmalz, Claudia; Sherman, Allen C; Tomaszewska, Iwona M; Verdonck de Leeuw, Irma; Yarom, Noam; Zotti, Paola; Hofmeister, Dirk

2015-09-01

The objective of this study was to pilot test an updated version of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Head and Neck Module (EORTC QLQ-H&N60). Patients with head and neck cancer were asked to complete a list of 60 head and neck cancer-specific items comprising the updated EORTC head and neck module and the core questionnaire EORTC QLQ-C30. Debriefing interviews were conducted to identify any irrelevant items and confusing or upsetting wording. Interviews were performed with 330 patients from 17 countries, representing different head and neck cancer sites and treatments. Forty-one of the 60 items were retained according to the predefined EORTC criteria for module development, for another 2 items the wording was refined, and 17 items were removed. The preliminary EORTC QLQ-H&N43 can now be used in academic research. Psychometrics will be tested in a larger field study. © 2014 Wiley Periodicals, Inc.

Simple tool for prediction of parotid gland sparing in intensity-modulated radiation therapy.

PubMed

Gensheimer, Michael F; Hummel-Kramer, Sharon M; Cain, David; Quang, Tony S

2015-01-01

Sparing one or both parotid glands is a key goal when planning head and neck cancer radiation treatment. If the planning target volume (PTV) overlaps one or both parotid glands substantially, it may not be possible to achieve adequate gland sparing. This finding results in physicians revising their PTV contours after an intensity-modulated radiation therapy (IMRT) plan has been run and reduces workflow efficiency. We devised a simple formula for predicting mean parotid gland dose from the overlap of the parotid gland and isotropically expanded PTV contours. We tested the tool using 44 patients from 2 institutions and found agreement between predicted and actual parotid gland doses (mean absolute error = 5.3 Gy). This simple method could increase treatment planning efficiency by improving the chance that the first plan presented to the physician will have optimal parotid gland sparing. Published by Elsevier Inc.

Simple tool for prediction of parotid gland sparing in intensity-modulated radiation therapy

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

Gensheimer, Michael F.; Hummel-Kramer, Sharon M., E-mail: sharonhummel@comcast.net; Cain, David

Sparing one or both parotid glands is a key goal when planning head and neck cancer radiation treatment. If the planning target volume (PTV) overlaps one or both parotid glands substantially, it may not be possible to achieve adequate gland sparing. This finding results in physicians revising their PTV contours after an intensity-modulated radiation therapy (IMRT) plan has been run and reduces workflow efficiency. We devised a simple formula for predicting mean parotid gland dose from the overlap of the parotid gland and isotropically expanded PTV contours. We tested the tool using 44 patients from 2 institutions and found agreementmore » between predicted and actual parotid gland doses (mean absolute error = 5.3 Gy). This simple method could increase treatment planning efficiency by improving the chance that the first plan presented to the physician will have optimal parotid gland sparing.« less

Accuracy and reproducibility of aortic annular measurements obtained from echocardiographic 3D manual and semi-automated software analyses in patients referred for transcatheter aortic valve implantation: implication for prosthesis size selection.

PubMed

Stella, Stefano; Italia, Leonardo; Geremia, Giulia; Rosa, Isabella; Ancona, Francesco; Marini, Claudia; Capogrosso, Cristina; Giglio, Manuela; Montorfano, Matteo; Latib, Azeem; Margonato, Alberto; Colombo, Antonio; Agricola, Eustachio

2018-02-06

A 3D transoesophageal echocardiography (3D-TOE) reconstruction tool has recently been introduced. The system automatically configures a geometric model of the aortic root and performs quantitative analysis of these structures. We compared the measurements of the aortic annulus (AA) obtained by semi-automated 3D-TOE quantitative software and manual analysis vs. multislice computed tomography (MSCT) ones. One hundred and seventy-five patients (mean age 81.3 ± 6.3 years, 77 men) who underwent both MSCT and 3D-TOE for annulus assessment before transcatheter aortic valve implantation were analysed. Hypothetical prosthetic valve sizing was evaluated using the 3D manual, semi-automated measurements using manufacturer-recommended CT-based sizing algorithm as gold standard. Good correlation between 3D-TOE methods vs. MSCT measurements was found, but the semi-automated analysis demonstrated slightly better correlations for AA major diameter (r = 0.89), perimeter (r = 0.89), and area (r = 0.85) (all P < 0.0001) than manual one. Both 3D methods underestimated the MSCT measurements, but semi-automated measurements showed narrower limits of agreement and lesser bias than manual measurements for most of AA parameters. On average, 3D-TOE semi-automated major diameter, area, and perimeter underestimated the respective MSCT measurements by 7.4%, 3.5%, and 4.4%, respectively, whereas minor diameter was overestimated by 0.3%. Moderate agreement for valve sizing for both 3D-TOE techniques was found: Kappa agreement 0.5 for both semi-automated and manual analysis. Interobserver and intraobserver agreements for the AA measurements were excellent for both techniques (intraclass correlation coefficients for all parameters >0.80). The 3D-TOE semi-automated analysis of AA is feasible and reliable and can be used in clinical practice as an alternative to MSCT for AA assessment. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2018. For permissions, please email: journals.permissions@oup.com.

NEW DEVELOPMENTS IN RADIATION THERAPY FOR HEAD AND NECK CANCER: INTENSITY MODULATED RADIATION THERAPY AND HYPOXIA TARGETING

PubMed Central

Lee, Nancy Y.; Le, Quynh-Thu

2008-01-01

Intensity modulated radiation therapy (IMRT) has revolutionized radiation treatment for head and neck cancers (HNC). When compared to the traditional techniques, IMRT has the unique ability to minimize the dose delivered to normal tissues without compromising tumor coverage. As a result, side effects from high dose radiation have decreased and patient quality of life has improved. In addition to toxicity reduction, excellent clinical outcomes have been reported for IMRT. The first part of this review will focus on clinical results of IMRT for HNC. Tumor hypoxia or the condition of low oxygen is a key factor for tumor progression and treatment resistance. Hypoxia develops in solid tumors due to aberrant blood vessel formation, fluctuation in blood flow and increasing oxygen demands for tumor growth. Because hypoxic tumor cells are more resistant to ionizing radiation, hypoxia has been a focus of clinical research in radiation therapy for half a decade. Interest for targeting tumor hypoxia have waxed and waned as promising treatments emerged from the laboratory, only to fail in the clinics. However, with the development of new technologies, the prospect of targeting tumor hypoxia is more tangible. The second half of the review will focus on approaches for assessing tumor hypoxia and on the strategies for targeting this important microenvironmental factor in HNC. PMID:18544439

Head and Neck Margin Reduction With Adaptive Radiation Therapy: Robustness of Treatment Plans Against Anatomy Changes

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

Kranen, Simon van; Hamming-Vrieze, Olga; Wolf, Annelisa

Purpose: We set out to investigate loss of target coverage from anatomy changes in head and neck cancer patients as a function of applied safety margins and to verify a cone beam computed tomography (CBCT)–based adaptive strategy with an average patient anatomy to overcome possible target underdosage. Methods and Materials: For 19 oropharyngeal cancer patients, volumetric modulated arc therapy treatment plans (2 arcs; simultaneous integrated boost, 70 and 54.25 Gy; 35 fractions) were automatically optimized with uniform clinical target volume (CTV)–to–planning target volume margins of 5, 3, and 0 mm. We applied b-spline CBCT–to–computed tomography (CT) deformable registration to allow recalculation ofmore » the dose on modified CT scans (planning CT deformed to daily CBCT following online positioning) and dose accumulation in the planning CT scan. Patients with deviations in primary or elective CTV coverage >2 Gy were identified as candidates for adaptive replanning. For these patients, a single adaptive intervention was simulated with an average anatomy from the first 10 fractions. Results: Margin reduction from 5 mm to 3 mm to 0 mm generally led to an organ-at-risk (OAR) mean dose (D{sub mean}) sparing of approximately 1 Gy/mm. CTV shrinkage was mainly seen in the elective volumes (up to 10%), likely related to weight loss. Despite online repositioning, substantial systematic errors were present (>3 mm) in lymph node CTV, the parotid glands, and the larynx. Nevertheless, the average increase in OAR dose was small: maximum of 1.2 Gy (parotid glands, D{sub mean}) for all applied margins. Loss of CTV coverage >2 Gy was found in 1, 3, and 7 of 73 CTVs, respectively. Adaptive intervention in 0-mm plans substantially improved coverage: in 5 of 7 CTVs (in 6 patients) to <2 Gy of initially planned. Conclusions: Volumetric modulated arc therapy head and neck cancer treatment plans with 5-mm margins are robust for anatomy changes and show a modest increase in OAR dose. Margin reduction improves OAR sparing with approximately 1 Gy/mm at the expense of target coverage in a subgroup of patients. Patients at risk of CTV underdosage >2 Gy in 0-mm plans may be identified early in treatment using dose accumulation. A single intervention with an average anatomy derived from CBCT effectively mitigates discrepancies.« less

MO-H-19A-02: Investigation of Modulated Electron Arc (MeArc) Therapy for the Treatment of Scalp Tumors

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

Eldib, A; Al-Azhar University, Cairo; Jin, L

2014-06-15

Purpose: Electron arc therapy has long been proposed as the most suitable technique for the treatment of superficial tumors that follow circularly curved surfaces. However it was challenged by unsuitability of the conventional applicators and the lack of adequate 3-D dose calculation tools for arc electron beams in the treatment planning systems (TPS). Now with the availability of an electron specific multi-leaf collimator (eMLC) and an in-house Monte Carlo (MC) based TPS, we were motivated to investigate more advanced modulated electron arc (MeARC) therapy and its beneficial outcome. Methods: We initiated the study by a film measurement conducted in amore » head and neck phantom, where we delivered electron arcs in a step and shoot manner using the light field as a guide to avoid fields abutments. This step was done to insure enough clearance for the arcs with eMLC. MCBEAM and MCPLAN MC codes were used for the treatment head simulation and phantom dose calculation, respectively. Treatment plans were generated for targets drawn in real patient CTs and head and neck phantom. We utilized beams eye view available from a commercial planning system to create beamlets having same isocenter and adjoined at the scalp surface. Then dose-deposition coefficients from those beamlets were calculated for all electron energies using MCPLAN. An in-house optimization code was then used to find the optimum weights needed from individual beamlets. Results: MeARC showed a nicely tailored dose distribution around the circular curved target on the scalp. Some hot spots were noticed and could be attributed to fields abutment problem owing to the bulging nature of electron profiles. Brain dose was shown to be at lower levels compared to photon treatment. Conclusion: MeARC was shown to be a promising modality for treating scalp cases and could be beneficial to all superficial tumors with a circular curvature.« less

Preliminary analysis of the sequential simultaneous integrated boost technique for intensity-modulated radiotherapy for head and neck cancers.

PubMed

Miyazaki, Masayoshi; Nishiyama, Kinji; Ueda, Yoshihiro; Ohira, Shingo; Tsujii, Katsutomo; Isono, Masaru; Masaoka, Akira; Teshima, Teruki

2016-07-01

The aim of this study was to compare three strategies for intensity-modulated radiotherapy (IMRT) for 20 head-and-neck cancer patients. For simultaneous integrated boost (SIB), doses were 66 and 54 Gy in 30 fractions for PTVboost and PTVelective, respectively. Two-phase IMRT delivered 50 Gy in 25 fractions to PTVelective in the First Plan, and 20 Gy in 10 fractions to PTVboost in the Second Plan. Sequential SIB (SEQ-SIB) delivered 55 Gy and 50 Gy in 25 fractions, respectively, to PTVboost and PTVelective using SIB in the First Plan and 11 Gy in 5 fractions to PTVboost in the Second Plan. Conformity indexes (CIs) (mean ± SD) for PTVboost and PTVelective were 1.09 ± 0.05 and 1.34 ± 0.12 for SIB, 1.39 ± 0.14 and 1.80 ± 0.28 for two-phase IMRT, and 1.14 ± 0.07 and 1.60 ± 0.18 for SEQ-SIB, respectively. CI was significantly highest for two-phase IMRT. Maximum doses (Dmax) to the spinal cord were 42.1 ± 1.5 Gy for SIB, 43.9 ± 1.0 Gy for two-phase IMRT and 40.3 ± 1.8 Gy for SEQ-SIB. Brainstem Dmax were 50.1 ± 2.2 Gy for SIB, 50.5 ± 4.6 Gy for two-phase IMRT and 47.4 ± 3.6 Gy for SEQ-SIB. Spinal cord Dmax for the three techniques was significantly different, and brainstem Dmax was significantly lower for SEQ-SIB. The compromised conformity of two-phase IMRT can result in higher doses to organs at risk (OARs). Lower OAR doses in SEQ-SIB made SEQ-SIB an alternative to SIB, which applies unconventional doses per fraction. © The Author 2016. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

The impact of different cone beam computed tomography and multi-slice computed tomography scan parameters on virtual three-dimensional model accuracy using a highly precise ex vivo evaluation method.

PubMed

Matta, Ragai-Edward; von Wilmowsky, Cornelius; Neuhuber, Winfried; Lell, Michael; Neukam, Friedrich W; Adler, Werner; Wichmann, Manfred; Bergauer, Bastian

2016-05-01

Multi-slice computed tomography (MSCT) and cone beam computed tomography (CBCT) are indispensable imaging techniques in advanced medicine. The possibility of creating virtual and corporal three-dimensional (3D) models enables detailed planning in craniofacial and oral surgery. The objective of this study was to evaluate the impact of different scan protocols for CBCT and MSCT on virtual 3D model accuracy using a software-based evaluation method that excludes human measurement errors. MSCT and CBCT scans with different manufacturers' predefined scan protocols were obtained from a human lower jaw and were superimposed with a master model generated by an optical scan of an industrial noncontact scanner. To determine the accuracy, the mean and standard deviations were calculated, and t-tests were used for comparisons between the different settings. Averaged over 10 repeated X-ray scans per method and 19 measurement points per scan (n = 190), it was found that the MSCT scan protocol 140 kV delivered the most accurate virtual 3D model, with a mean deviation of 0.106 mm compared to the master model. Only the CBCT scans with 0.2-voxel resolution delivered a similar accurate 3D model (mean deviation 0.119 mm). Within the limitations of this study, it was demonstrated that the accuracy of a 3D model of the lower jaw depends on the protocol used for MSCT and CBCT scans. Copyright © 2016 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Coronary Events and Anatomy After Arterial Switch Operation for Transposition of the Great Arteries: Detection by 16-Row Multislice Computed Tomography Angiography in Pediatric Patients

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

Oztunc, Funda, E-mail: foztunc@yahoo.com; Baris, Safa, E-mail: safabaris@hotmail.co; Adaletli, Ibrahim, E-mail: iadaletli@yahoo.com

2009-03-15

The purpose of this study was to evaluate the feasibility of multislice computed tomographic (MSCT) angiography as a noninvasive method for detecting ostial, proximal, and middle segment coronary stenosis or occlusion and anatomy in patients with transposition of the great arteries who had undergone arterial switch operation (ASO). Sixteen-detector-row MSCT angiography was performed in 16 patients treated with ASO for transposition of the great arteries. The median age was 10.3 years (range, 6.2-16.3 years). Sixteen-detector-row MSCT angiography was performed in 16 patients who had undergone ASO. CT imaging was performed in the craniocaudal direction from 2 cm above the carinamore » up to the heart basis. Noninvasive assessment of coronary artery stenosis and anatomy were investigated by MSCT angiography. Two patients were excluded from the study because of artifacts. Of 14 evaluated patients, 1 patient had ostial stenosis (7.1%). A coronary artery anatomy variant was present in six patients: left main artery (LMA) and right coronary artery (RCA) originating from the right sinus as a single orifice (n = 2); left circumflex artery (LCX) originating from the RCA (n = 1); LMA and RCA, after branching to the LCX, originating separately from the right sinus (n = 1); and LMA (n = 1) and left anterior descending artery (LADA; n = 1) originating directly from the right sinus. Intramural bridging in the LAD (n = 2) was detected. Five patients were normal. In conclusion, MSCT angiography, as a noninvasive, feasible technique for assessing coronary stenosis or occlusion and anatomy, can be used in the follow-up of patients who have undergone ASO.« less

Detection of crestal radiolucencies around dental implants: an in vitro experimental study.

PubMed

Sirin, Yigit; Horasan, Sinan; Yaman, Duygu; Basegmez, Cansu; Tanyel, Cem; Aral, Ali; Guven, Koray

2012-07-01

The aim of this study was to compare the diagnostic potentials and practical advantages of different imaging modalities in detecting bone defects around dental implants. Crestal bone defects with sequentially larger diameters were randomly prepared around 100 implants that were inserted in bovine bone blocks. Conventional periapical radiography (PR), direct digital radiography (DDR), panoramic radiography (PANO), cone-beam computed tomography (CBCT), and multislice computed tomography (MSCT) were performed for all specimens. The diagnostic accuracies of the devices, confidence of the answers, subjective image quality, defect visibility in planar orientations, and duration of diagnosis were analyzed based on the interpretations of 7 calibrated observers. The agreement levels of intra- and interobserver scores were rated good. PR, DDR, and CBCT were mostly more accurate than PANO and MSCT (P < .05). Confidence levels were positively correlated with the defect size (ρ = 0.20, P < .01), and that of DDR was the highest (P < .05). The subjective image quality of PR and DDR was higher than that of CBCT, PANO, and MSCT (P < .05 for all comparisons). Axial-coronal-sagittal visibilities of the defects were higher for CBCT compared with MSCT (P < .05). The diagnostic time was shorter for DDR (P < .05) and longer for the tomographic systems (P < .05) than for the other devices. DDR may provide a faster and more confident diagnostic option that is as accurate as PR in detecting peri-implant radiolucencies. CBCT has a comparable potential to these intraoral systems but with slower decision making and lower image quality, whereas PANO and MSCT become more reliable when bone defects have a diameter that is at least 1.5 mm larger than that of the implant. Copyright © 2012 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Highly preserved consensus gene modules in human papilloma virus 16 positive cervical cancer and head and neck cancers.

PubMed

Zhang, Xianglan; Cha, In-Ho; Kim, Ki-Yeol

2017-12-26

In this study, we investigated the consensus gene modules in head and neck cancer (HNC) and cervical cancer (CC). We used a publicly available gene expression dataset, GSE6791, which included 42 HNC, 14 normal head and neck, 20 CC and 8 normal cervical tissue samples. To exclude bias because of different human papilloma virus (HPV) types, we analyzed HPV16-positive samples only. We identified 3824 genes common to HNC and CC samples. Among these, 977 genes showed high connectivity and were used to construct consensus modules. We demonstrated eight consensus gene modules for HNC and CC using the dissimilarity measure and average linkage hierarchical clustering methods. These consensus modules included genes with significant biological functions, including ATP binding and extracellular exosome. Eigengen network analysis revealed the consensus modules were highly preserved with high connectivity. These findings demonstrate that HPV16-positive head and neck and cervical cancers share highly preserved consensus gene modules with common potentially therapeutic targets.

Highly preserved consensus gene modules in human papilloma virus 16 positive cervical cancer and head and neck cancers

PubMed Central

Zhang, Xianglan; Cha, In-Ho; Kim, Ki-Yeol

2017-01-01

In this study, we investigated the consensus gene modules in head and neck cancer (HNC) and cervical cancer (CC). We used a publicly available gene expression dataset, GSE6791, which included 42 HNC, 14 normal head and neck, 20 CC and 8 normal cervical tissue samples. To exclude bias because of different human papilloma virus (HPV) types, we analyzed HPV16-positive samples only. We identified 3824 genes common to HNC and CC samples. Among these, 977 genes showed high connectivity and were used to construct consensus modules. We demonstrated eight consensus gene modules for HNC and CC using the dissimilarity measure and average linkage hierarchical clustering methods. These consensus modules included genes with significant biological functions, including ATP binding and extracellular exosome. Eigengen network analysis revealed the consensus modules were highly preserved with high connectivity. These findings demonstrate that HPV16-positive head and neck and cervical cancers share highly preserved consensus gene modules with common potentially therapeutic targets. PMID:29371966

SU-F-T-205: Effectiveness of Robust Treatment Planning to Account for Inter- Fractional Variation in Intensity Modulated Proton Therapy for Head Neck Cancer

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

Li, X; Zhang, J; Qin, A

2016-06-15

Purpose: To evaluate the potential benefits of robust optimization in intensity modulated proton therapy(IMPT) treatment planning to account for inter-fractional variation for Head Neck Cancer(HNC). Methods: One patient with bilateral HNC previous treated at our institution was used in this study. Ten daily CBCTs were selected. The CT numbers of the CBCTs were corrected by mapping the CT numbers from simulation CT via Deformable Image Registration. The planning target volumes(PTVs) were defined by a 3mm expansion from clinical target volumes(CTVs). The prescription was 70Gy, 54Gy to CTV1, CTV2, and PTV1, PTV2 for robust optimized(RO) and conventionally optimized(CO) plans respectively. Bothmore » techniques were generated by RayStation with the same beam angles: two anterior oblique and two posterior oblique angles. The similar dose constraints were used to achieve 99% of CTV1 received 100% prescription dose while kept the hotspots less than 110% of the prescription. In order to evaluate the dosimetric result through the course of treatment, the contours were deformed from simulation CT to daily CBCTs, modified, and approved by a radiation oncologist. The initial plan on the simulation CT was re-replayed on the daily CBCTs followed the bony alignment. The target coverage was evaluated using the daily doses and the cumulative dose. Results: Eight of 10 daily deliveries with using RO plan achieved at least 95% prescription dose to CTV1 and CTV2, while still kept maximum hotspot less than 112% of prescription compared with only one of 10 for the CO plan to achieve the same standards. For the cumulative doses, the target coverage for both RO and CO plans was quite similar, which was due to the compensation of cold and hot spots. Conclusion: Robust optimization can be effectively applied to compensate for target dose deficit caused by inter-fractional target geometric variation in IMPT treatment planning.« less

Determination of multislice computed tomography dose index (CTDI) using optically stimulated luminescence technology.

PubMed

Ruan, Chun; Yukihara, Eduardo G; Clouse, William J; Gasparian, Patricia B R; Ahmad, Salahuddin

2010-07-01

The extensive use of multislice computed tomography (MSCT) and the associated increase in patient dose calls for an accurate dose evaluation technique. Optically stimulated luminescence (OSL) dosimetry provides a potential solution to the arising concerns over patient dose. This study was intended to evaluate the feasibility and accuracy of OSL dosimeter systems in the diagnostic CT x-ray beam energy range. MSCT dose profiles were measured by irradiating OSL strips placed inside the extended PMMA head and body phantoms at different scan conditions by varying kVp settings (100, 120, and 140 kVp) and collimated beam widths (5, 10, 20, and 40 mm). All scans in this study were performed using a GE Lightspeed VCT scanner in axial mode. The exposed strips were then read out using a custom-made OSL strip reader and corrected with field-specific conversion factors. Based on the corrected OSL dose profile, the CTDI(450-OSL) and CTDI(l00-OSL) were evaluated. CTDI(100-IC) was also obtained using a 100 mm long pencil ionization chamber for accuracy verification. CTDI(100-efficiency) can be further evaluated by calculating the ratio of CTDI(100-OSL) and CTDI(450-OSL), which was compared to results from previous studies as well. The OSL detectors were found to have good sensitivity and dose response over a wide range of diagnostic CT x-ray beam energy viz. the primary beam and the scatter tail section of the dose profile. The differences between CTDI100 values obtained using the OSL strips and those obtained with 100 mm long pencil ionization chamber were < +/- 5% for all scan conditions, indicating good accuracy of the OSL system. It was also found that the CTDI(100-efficiency) did not significantly change as the beam width increased and tube voltage changed. The average CTDI(100-efficiency) at the center of the head and body phantoms were 72.6% and 56.2%, respectively. The corresponding values for the periphery of the head and body phantoms were 85.0% and 81.7%. These results agreed very well with previous results from the literature using other detection techniques or Monte Carlo simulations. The LED-based OSL system can be an accurate alternative device for CT dose evaluations. CTDI100 measurement with the use of a 100 mm pencil ionization chamber substantially underestimates the CTDIinfinity value even with 5 mm collimated beam width. The established complete set of CTDI(100-efficiency) correction factors for various scan parameters allows for accurately estimating CTDIinfinity with the current use of pencil chamber and dose phantoms. Combined with the simple calibration, it gives this work great potential to be used not only in routine clinical quality assurance checks but also as a promising tool for patient organ dose assessment.

SU-E-T-618: Plan Robustness Study of Volumetric-Modulated Arc Therapy Vs. Intensity-Modulated Radiation Therapy for Head and Neck Cancer

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

Liu, W; Patel, S; Shen, J

Purpose: Lack of plan robustness may contribute to local failure in volumetric-modulated arc therapy (VMAT) to treat head and neck (H&N) cancer. Thus we compared plan robustness of VMAT with intensity-modulated radiation therapy (IMRT). Methods: VMAT and IMRT plans were created for 9 H&N cancer patients. For each plan, six new perturbed dose distributions were computed — one each for ± 3mm setup deviations along the S-I, A-P and L-R directions. We used three robustness quantification tools: (1) worst-case analysis (WCA); (2) dose-volume histograms (DVHs) band (DVHB); and (3) root-mean-square-dose deviation (RMSD) volume histogram (DDVH). DDVH represents the relative volumemore » (y) on the vertical axis and the RMSD (x) on the horizontal axis. Similar to DVH, this means that y% of the volume of the indicated structure has the RMSD at least x Gy[RBE].The width from the first two methods at different target DVH indices (such as D95 and D5) and the area under the DDVH curves (AUC) for the target were used to indicate plan robustness. In these robustness quantification tools, the smaller the value, the more robust the plan is. Plan robustness evaluation metrics were compared using Wilcoxon test. Results: DVHB showed the width at D95 from IMRT to be larger than from VMAT (unit Gy) [1.59 vs 1.18 (p=0.49)], while the width at D5 from IMRT was found to be slightly larger than from VMAT [0.59 vs 0.54 (p=0.84)]. WCA showed similar results [D95: 3.28 vs 3.00 (p=0.56); D5: 1.68 vs 1.95 (p=0.23)]. DDVH showed the AUC from IMRT to be slightly smaller than from VMAT [1.13 vs 1.15 (p=0.43)]. Conclusion: VMAT plan robustness is comparable to IMRT plan robustness. The plan robustness conclusions from WCA and DVHB are DVH parameter dependent. On the other hand DDVH captures the overall effect of uncertainties on the dose to a volume of interest. NIH/NCI K25CA168984; Eagles Cancer Research Career Development; The Lawrence W. and Marilyn W. Matteson Fund for Cancer Research Mayo ASU Seed Grant; The Kemper Marley Foundation.« less

Adaptive Dose Painting by Numbers for Head-and-Neck Cancer

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

Duprez, Frederic, E-mail: frederic.duprez@ugent.be; De Neve, Wilfried; De Gersem, Werner

Purpose: To investigate the feasibility of adaptive intensity-modulated radiation therapy (IMRT) using dose painting by numbers (DPBN) for head-and-neck cancer. Methods and Materials: Each patient's treatment used three separate treatment plans: fractions 1-10 used a DPBN ([{sup 18}-F]fluoro-2-deoxy-D-glucose positron emission tomography [{sup 18}F-FDG-PET]) voxel intensity-based IMRT plan based on a pretreatment {sup 18}F-FDG-PET/computed tomography (CT) scan; fractions 11-20 used a DPBN plan based on a {sup 18}F-FDG-PET/CT scan acquired after the eighth fraction; and fractions 21-32 used a conventional (uniform dose) IMRT plan. In a Phase I trial, two dose prescription levels were tested: a median dose of 80.9 Gymore » to the high-dose clinical target volume (CTV{sub highdose}) (dose level I) and a median dose of 85.9 Gy to the gross tumor volume (GTV) (dose level II). Between February 2007 and August 2009, 7 patients at dose level I and 14 patients at dose level II were enrolled. Results: All patients finished treatment without a break, and no Grade 4 acute toxicity was observed. Treatment adaptation (i.e., plans based on the second {sup 18}F-FDG-PET/CT scan) reduced the volumes for the GTV (41%, p = 0.01), CTV{sub highdose} (18%, p = 0.01), high-dose planning target volume (14%, p = 0.02), and parotids (9-12%, p < 0.05). Because the GTV was much smaller than the CTV{sub highdose} and target adaptation, further dose escalation at dose level II resulted in less severe toxicity than that observed at dose level I. Conclusion: To our knowledge, this represents the first clinical study that combines adaptive treatments with dose painting by numbers. Treatment as described above is feasible.« less

Approximations of noise covariance in multi-slice helical CT scans: impact on lung nodule size estimation.

PubMed

Zeng, Rongping; Petrick, Nicholas; Gavrielides, Marios A; Myers, Kyle J

2011-10-07

Multi-slice computed tomography (MSCT) scanners have become popular volumetric imaging tools. Deterministic and random properties of the resulting CT scans have been studied in the literature. Due to the large number of voxels in the three-dimensional (3D) volumetric dataset, full characterization of the noise covariance in MSCT scans is difficult to tackle. However, as usage of such datasets for quantitative disease diagnosis grows, so does the importance of understanding the noise properties because of their effect on the accuracy of the clinical outcome. The goal of this work is to study noise covariance in the helical MSCT volumetric dataset. We explore possible approximations to the noise covariance matrix with reduced degrees of freedom, including voxel-based variance, one-dimensional (1D) correlation, two-dimensional (2D) in-plane correlation and the noise power spectrum (NPS). We further examine the effect of various noise covariance models on the accuracy of a prewhitening matched filter nodule size estimation strategy. Our simulation results suggest that the 1D longitudinal, 2D in-plane and NPS prewhitening approaches can improve the performance of nodule size estimation algorithms. When taking into account computational costs in determining noise characterizations, the NPS model may be the most efficient approximation to the MSCT noise covariance matrix.

Dosimetry of intracavitary placements for uterine and cervical carcinoma: results of orthogonal film, TLD, and CT-assisted techniques.

PubMed

Kapp, K S; Stuecklschweiger, G F; Kapp, D S; Hackl, A G

1992-07-01

A total of 720 192Ir high-dose-rate (HDR) applications in 331 patients with gynecological tumors were analyzed to evaluate the dose to normal tissues from brachytherapy. Based on the calculations of bladder base, bladder neck, and rectal doses derived from orthogonal films the planned tumor dose or fractionation was altered in 20.4% of intracavitary placements (ICP) for cervix carcinoma and 9.2% of ICP for treatment of the vaginal vault. In 13.8% of intracervical and 8.1% of intravaginal treatments calculated doses to both the bladder and rectum were greater than or equal to 140% of the initially planned dose fraction. Doses at the bladder base were significantly higher than at the bladder neck (p less than 0.001). In 17.5% of ICP the dose to the bladder base was at least twice as high as to the bladder neck. The ratio of bladder base dose to the bladder neck was 1.5 (+/- 1.19 SD) for intracervical and 1.46 (+/- 1.14 SD) for intravaginal applications. The comparison of calculated doses from orthogonal films with in-vivo readings showed a good correlation of rectal doses with a correlation coefficient factor of 0.9556. CT-assisted dosimetry, however, revealed that the maximum doses to bladder and rectum were generally higher than those obtained from films with ratios of 1-1.7 (average: 1.44) for the bladder neck, 1-5.4 (average: 2.42) for the bladder base, and 1.1-2.7 (average: 1.37) for the rectum. When doses to the specified reference points of bladder neck and rectum from orthogonal film dosimetry were compared with the corresponding points on CT scans, similar values were obtained for both methods with a maximum deviation of +/- 10%. Despite the determination of multiple reference points our study revealed that this information was inadequate to predict doses to the entire rectum and bladder. If conventional methods are used for dosimetry it is recommended that doses to the bladder base should be routinely calculated, since single point measurements at the bladder neck seriously underestimate the dose to the bladder. Also the rectal dose should be determined at several points over the length of the implant due to the wide range of anatomic variations possible.

Identification of Patient Benefit From Proton Therapy for Advanced Head and Neck Cancer Patients Based on Individual and Subgroup Normal Tissue Complication Probability Analysis

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

Jakobi, Annika, E-mail: Annika.Jakobi@OncoRay.de; Bandurska-Luque, Anna; Department of Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden

Purpose: The purpose of this study was to determine, by treatment plan comparison along with normal tissue complication probability (NTCP) modeling, whether a subpopulation of patients with head and neck squamous cell carcinoma (HNSCC) could be identified that would gain substantial benefit from proton therapy in terms of NTCP. Methods and Materials: For 45 HNSCC patients, intensity modulated radiation therapy (IMRT) was compared to intensity modulated proton therapy (IMPT). Physical dose distributions were evaluated as well as the resulting NTCP values, using modern models for acute mucositis, xerostomia, aspiration, dysphagia, laryngeal edema, and trismus. Patient subgroups were defined based onmore » primary tumor location. Results: Generally, IMPT reduced the NTCP values while keeping similar target coverage for all patients. Subgroup analyses revealed a higher individual reduction of swallowing-related side effects by IMPT for patients with tumors in the upper head and neck area, whereas the risk reduction of acute mucositis was more pronounced in patients with tumors in the larynx region. More patients with tumors in the upper head and neck area had a reduction in NTCP of more than 10%. Conclusions: Subgrouping can help to identify patients who may benefit more than others from the use of IMPT and, thus, can be a useful tool for a preselection of patients in the clinic where there are limited PT resources. Because the individual benefit differs within a subgroup, the relative merits should additionally be evaluated by individual treatment plan comparisons.« less

Modulation of Neck Intermuscular Beta Coherence during Voice and Speech Production

ERIC Educational Resources Information Center

Stepp, Cara E.; Hillman, Robert E.; Heaton, James T.

2011-01-01

Purpose: The purpose of this study was to better understand neck intermuscular beta coherence (15-35 Hz; NIBcoh) in healthy individuals, with respect to modulation by behavioral tasks. Method: Mean NIBcoh was measured using surface electromyography at 2 anterior neck locations in 10 individuals during normal speech, static nonspeech maneuvers,…

Dose dependence of true stress parameters in irradiated bcc, fcc, and hcp metals

NASA Astrophysics Data System (ADS)

Byun, T. S.

2007-04-01

The dose dependence of true stress parameters has been investigated for nuclear structural materials: A533B pressure vessel steels, modified 9Cr-1Mo and 9Cr-2WVTa ferritic martensitic steels, 316 and 316LN stainless steels, and Zircaloy-4. After irradiation to significant doses, these alloys show radiation-induced strengthening and often experience prompt necking at yield followed by large necking deformation. In the present work, the critical true stresses for deformation and fracture events, such as yield stress (YS), plastic instability stress (PIS), and true fracture stress (FS), were obtained from uniaxial tensile tests or calculated using a linear strain-hardening model for necking deformation. At low dose levels where no significant embrittlement was detected, the true fracture stress was nearly independent of dose. The plastic instability stress was also independent of dose before the critical dose-to-prompt-necking at yield was reached. A few bcc alloys such as ferritic martensitic steels experienced significant embrittlement at doses above ∼1 dpa; and the true fracture stress decreased with dose. The materials fractured before yield at or above 10 dpa.

A Clinical Concept for Interfractional Adaptive Radiation Therapy in the Treatment of Head and Neck Cancer

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

Jensen, Alexandra D., E-mail: Alexandra.Jensen@med.uni-heidelberg.de; Nill, Simeon; Huber, Peter E.

Purpose: To present an approach to fast, interfractional adaptive RT in intensity-modulated radiation therapy (IMRT) of head and neck tumors in clinical routine. Ensuring adequate patient position throughout treatment proves challenging in high-precision RT despite elaborate immobilization. Because of weight loss, treatment plans must be adapted to account for requiring supportive therapy incl. feeding tube or parenteral nutrition without treatment breaks. Methods and Materials: In-room CT position checks are used to create adapted IMRT treatment plans by stereotactic correlation to the initial setup, and volumes are adapted to the new geometry. New IMRT treatment plans are prospectively created on themore » basis of position control scans using the initial optimization parameters in KonRad without requiring complete reoptimization and thus facilitating quick replanning in daily routine. Patients treated for squamous cell head and neck cancer (SCCHN) in 2006-2007 were evaluated as to necessity/number of replannings, weight loss, dose, and plan parameters. Results: Seventy-two patients with SCCHN received IMRT to the primary site and lymph nodes (median dose 70.4 Gy). All patients received concomitant chemotherapy requiring supportive therapy by feeding tube or parenteral nutrition. Median weight loss was 7.8 kg, median volume loss was approximately 7%. Fifteen of 72 patients required adaptation of their treatment plans at least once. Target coverage was improved by up to 10.7% (median dose). The increase of dose to spared parotid without replanning was 11.7%. Replanning including outlining and optimization was feasible within 2 hours for each patient, and treatment could be continued without any interruptions. Conclusion: To preserve high-quality dose application, treatment plans must be adapted to anatomical changes. Replanning based on position control scans therefore presents a practical approach in clinical routine. In the absence of clinically usable online correction methods, this approach allows significant improvement of target volume coverage and continuous parotid sparing without treatment delays.« less

A clinical concept for interfractional adaptive radiation therapy in the treatment of head and neck cancer.

PubMed

Jensen, Alexandra D; Nill, Simeon; Huber, Peter E; Bendl, Rolf; Debus, Jürgen; Münter, Marc W

2012-02-01

To present an approach to fast, interfractional adaptive RT in intensity-modulated radiation therapy (IMRT) of head and neck tumors in clinical routine. Ensuring adequate patient position throughout treatment proves challenging in high-precision RT despite elaborate immobilization. Because of weight loss, treatment plans must be adapted to account for requiring supportive therapy incl. feeding tube or parenteral nutrition without treatment breaks. In-room CT position checks are used to create adapted IMRT treatment plans by stereotactic correlation to the initial setup, and volumes are adapted to the new geometry. New IMRT treatment plans are prospectively created on the basis of position control scans using the initial optimization parameters in KonRad without requiring complete reoptimization and thus facilitating quick replanning in daily routine. Patients treated for squamous cell head and neck cancer (SCCHN) in 2006-2007 were evaluated as to necessity/number of replannings, weight loss, dose, and plan parameters. Seventy-two patients with SCCHN received IMRT to the primary site and lymph nodes (median dose 70.4 Gy). All patients received concomitant chemotherapy requiring supportive therapy by feeding tube or parenteral nutrition. Median weight loss was 7.8 kg, median volume loss was approximately 7%. Fifteen of 72 patients required adaptation of their treatment plans at least once. Target coverage was improved by up to 10.7% (median dose). The increase of dose to spared parotid without replanning was 11.7%. Replanning including outlining and optimization was feasible within 2 hours for each patient, and treatment could be continued without any interruptions. To preserve high-quality dose application, treatment plans must be adapted to anatomical changes. Replanning based on position control scans therefore presents a practical approach in clinical routine. In the absence of clinically usable online correction methods, this approach allows significant improvement of target volume coverage and continuous parotid sparing without treatment delays. Copyright © 2012 Elsevier Inc. All rights reserved.

Hyperfractionated accelerated radiotherapy with concomitant integrated boost of 70-75 Gy in 5 weeks for advanced head and neck cancer. A phase I dose escalation study.

PubMed

Cvek, J; Kubes, J; Skacelikova, E; Otahal, B; Kominek, P; Halamka, M; Feltl, D

2012-08-01

The present study was performed to evaluate the feasibility of a new, 5-week regimen of 70-75 Gy hyperfractionated accelerated radiotherapy with concomitant integrated boost (HARTCIB) for locally advanced, inoperable head and neck cancer. A total of 39 patients with very advanced, stage IV nonmetastatic head and neck squamous cell carcinoma (median gross tumor volume 72 ml) were included in this phase I dose escalation study. A total of 50 fractions intensity-modulated radiotherapy (IMRT) were administered twice daily over 5 weeks. Prescribed total dose/dose per fraction for planning target volume (PTV(tumor)) were 70 Gy in 1.4 Gy fractions, 72.5 Gy in 1.45 Gy fractions, and 75 Gy in 1.5 Gy fractions for 10, 13, and 16 patients, respectively. Uninvolved lymphatic nodes (PTV(uninvolved)) were irradiated with 55 Gy in 1.1 Gy fractions using the concomitant integrated boost. Acute toxicity was evaluated according to the RTOG/EORTC scale; the incidence of grade 3 mucositis was 51% in the oral cavity/pharynx and 0% in skin and the recovery time was ≤ 9 weeks for all patients. Late toxicity was evaluated in patients in complete remission according to the RTOG/EORTC scale. No grade 3/4 late toxicity was observed. The 1-year locoregional progression-free survival was 50% and overall survival was 55%. HARTCIB (75 Gy in 5 weeks) is feasible for patients deemed unsuitable for chemoradiation. Acute toxicity was lower than predicted from radiobiological models; duration of dysphagia and confluent mucositis were particularly short. Better conformity of radiotherapy allows the use of more intensive altered fractionation schedules compared with older studies. These results suggest that further dose escalation might be possible when highly conformal techniques (e.g., stereotactic radiotherapy) are used.

Dose calculation accuracy of different image value to density tables for cone-beam CT planning in head & neck and pelvic localizations.

PubMed

Barateau, Anaïs; Garlopeau, Christopher; Cugny, Audrey; De Figueiredo, Bénédicte Henriques; Dupin, Charles; Caron, Jérôme; Antoine, Mikaël

2015-03-01

We aimed to identify the most accurate combination of phantom and protocol for image value to density table (IVDT) on volume-modulated arc therapy (VMAT) dose calculation based on kV-Cone-beam CT imaging, for head and neck (H&N) and pelvic localizations. Three phantoms (Catphan(®)600, CIRS(®)062M (inner phantom for head and outer phantom for body), and TomoTherapy(®) "Cheese" phantom) were used to create IVDT curves of CBCT systems with two different CBCT protocols (Standard-dose Head and Standard Pelvis). Hounsfield Unit (HU) time stability and repeatability for a single On-Board-Imager (OBI) and compatibility of two distinct devices were assessed with Catphan(®)600. Images from the anthropomorphic phantom CIRS ATOM(®) for both CT and CBCT modalities were used for VMAT dose calculation from different IVDT curves. Dosimetric indices from CT and CBCT imaging were compared. IVDT curves from CBCT images were highly different depending on phantom used (up to 1000 HU for high densities) and protocol applied (up to 200 HU for high densities). HU time stability was verified over seven weeks. A maximum difference of 3% on the dose calculation indices studied was found between CT and CBCT VMAT dose calculation across the two localizations using appropriate IVDT curves. One IVDT curve per localization can be established with a bi-monthly verification of IVDT-CBCT. The IVDT-CBCTCIRS-Head phantom with the Standard-dose Head protocol was the most accurate combination for dose calculation on H&N CBCT images. For pelvic localizations, the IVDT-CBCTCheese established with the Standard Pelvis protocol provided the best accuracy. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Radical chemo-irradiation using intensity-modulated radiotherapy for locally advanced head and neck cancer in elderly patients: Experience from a tertiary care center in South India.

PubMed

Chalissery, J R; Sudheeran, P C; Varghese, K M; Venkatesan, K

2016-01-01

To assess the feasibility, tolerance and response of radical chemo irradiation using Intensity modulated Radiotherapy [IMRT] in elderly patients [age >65] with locally advanced head and neck cancer. Patients aged 65 and above [range 65 to 84years] registered in oncology outpatient unit in our institution between December 2011 to 2014, with stage III and IV head and neck cancer were treated with radical dose of radiotherapy using IMRT and concurrent chemotherapy with cisplatin 40mg/sq.m weekly. Response evaluation and toxicity profile assessment was done 6 to 8 weeks after completion of treatment and 3 monthly thereafter with median follow up of 3 years. Total number of patients analysed were 47. 43(91.5%) patients tolerated 66-.70Gy of radiotherapy and 4 or more cycles of weekly chemotherapy with cisplatin. First follow up evaluation at 6 to 8 weeks showed 81% patients having complete loco regional response. Grade III skin reaction and mucositis was noticed in 24% and 47% respectively. No grade III neutropenia observed. Median follow up of 3 years showed a complete local control in 53% and overall survival of 60%. Radical chemo irradiation with IMRT in elderly patients is a feasible option. Long term local control and overall survival benefits needs to be followed up.

Relationship between Eustachian tube dysfunction and otitis media with effusion in radiotherapy patients.

PubMed

Akazawa, K; Doi, H; Ohta, S; Terada, T; Fujiwara, M; Uwa, N; Tanooka, M; Sakagami, M

2018-02-01

This study evaluated the relationship between radiation and Eustachian tube dysfunction, and examined the radiation dose required to induce otitis media with effusion. The function of 36 Eustachian tubes in 18 patients with head and neck cancer were examined sonotubometrically before, during, and 1, 2 and 3 months after, intensity-modulated radiotherapy. Patients with an increase of 5 dB or less in sound pressure level (dB) during swallowing were categorised as being in the dysfunction group. Additionally, radiation dose distributions were assessed in all Eustachian tubes using three dose-volume histogram parameters. Twenty-two of 25 normally functioning Eustachian tubes before radiotherapy (88.0 per cent) shifted to the dysfunction group after therapy. All ears that developed otitis media with effusion belonged to the dysfunction group. The radiation dose threshold evaluation revealed that ears with otitis media with effusion received significantly higher doses to the Eustachian tubes. The results indicate a relationship between radiation dose and Eustachian tube dysfunction and otitis media with effusion.

Technical note: estimating absorbed doses to the thyroid in CT.

PubMed

Huda, Walter; Magill, Dennise; Spampinato, Maria V

2011-06-01

To describe a method for estimating absorbed doses to the thyroid in patients undergoing neck CT examinations. Thyroid doses in anthropomorphic phantoms were obtained for all 23 scanner dosimetry data sets in the ImPACT CT patient dosimetry calculator. Values of relative thyroid dose [R(thy)(L)], defined as the thyroid dose for a given scan length (L) divided by the corresponding thyroid dose for a whole body scan, were determined for neck CT scans. Ratios of the maximum thyroid dose to the corresponding CTDI(vol) and [D'(thy)], were obtained for two phantom diameters. The mass-equivalent water cylinder of any patient can be derived from the neck cross-sectional area and the corresponding average Hounsfield Unit, and compared to the 16.5-cm diameter water cylinder that models the ImPACT anthropomorphic phantom neck. Published values of relative doses in water cylinders of varying diameter were used to adjust thyroid doses in the anthropomorphic phantom to those of any sized patient. Relative thyroid doses R(thy)(L) increase to unity with increasing scan length and with very small difference between scanners. A 10-cm scan centered on the thyroid would result in a dose that is, nearly 90% of the thyroid dose from a whole body scan when performed using the constant radiographic techniques. At 120 kV, the average value of D'(thy) for the 16-cm diameter was 1.17 +/- 0.05 and was independent of CT vendor and year of CT scanner, and choice of x-ray tube voltage. The corresponding average value of D'(thy) in the 32-cm diameter phantom was 2.28 +/- 0.22 and showed marked variations depending on vendor, year of introduction into clinical practice as well as x-ray tube voltage. At 120 kV, a neck equivalent to a 10-cm diameter cylinder of water would have thyroid doses 36% higher than those in the ImPACT phantom, whereas a neck equivalent to a 25-cm cylinder diameter would have thyroid doses 35% lower. Patient thyroid doses can be estimated by taking into account the amount of radiation used to perform the CT examination (CTDI(vol)) and accounting for scan length and patient anatomy (i.e., neck diameter) at the thyroid location.

Optimal field-splitting algorithm in intensity-modulated radiotherapy: Evaluations using head-and-neck and female pelvic IMRT cases

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

Dou, Xin; Kim, Yusung, E-mail: yusung-kim@uiowa.edu; Bayouth, John E.

2013-04-01

To develop an optimal field-splitting algorithm of minimal complexity and verify the algorithm using head-and-neck (H and N) and female pelvic intensity-modulated radiotherapy (IMRT) cases. An optimal field-splitting algorithm was developed in which a large intensity map (IM) was split into multiple sub-IMs (≥2). The algorithm reduced the total complexity by minimizing the monitor units (MU) delivered and segment number of each sub-IM. The algorithm was verified through comparison studies with the algorithm as used in a commercial treatment planning system. Seven IMRT, H and N, and female pelvic cancer cases (54 IMs) were analyzed by MU, segment numbers, andmore » dose distributions. The optimal field-splitting algorithm was found to reduce both total MU and the total number of segments. We found on average a 7.9 ± 11.8% and 9.6 ± 18.2% reduction in MU and segment numbers for H and N IMRT cases with an 11.9 ± 17.4% and 11.1 ± 13.7% reduction for female pelvic cases. The overall percent (absolute) reduction in the numbers of MU and segments were found to be on average −9.7 ± 14.6% (−15 ± 25 MU) and −10.3 ± 16.3% (−3 ± 5), respectively. In addition, all dose distributions from the optimal field-splitting method showed improved dose distributions. The optimal field-splitting algorithm shows considerable improvements in both total MU and total segment number. The algorithm is expected to be beneficial for the radiotherapy treatment of large-field IMRT.« less

Midline Dose Verification with Diode In Vivo Dosimetry for External Photon Therapy of Head and Neck and Pelvis Cancers During Initial Large-Field Treatments

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

Tung, Chuan-Jong; Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan; Yu, Pei-Chieh

2010-01-01

During radiotherapy treatments, quality assurance/control is essential, particularly dose delivery to patients. This study was designed to verify midline doses with diode in vivo dosimetry. Dosimetry was studied for 6-MV bilateral fields in head and neck cancer treatments and 10-MV bilateral and anteroposterior/posteroanterior (AP/PA) fields in pelvic cancer treatments. Calibrations with corrections of diodes were performed using plastic water phantoms; 190 and 100 portals were studied for head and neck and pelvis treatments, respectively. Calculations of midline doses were made using the midline transmission, arithmetic mean, and geometric mean algorithms. These midline doses were compared with the treatment planning systemmore » target doses for lateral or AP (PA) portals and paired opposed portals. For head and neck treatments, all 3 algorithms were satisfactory, although the geometric mean algorithm was less accurate and more uncertain. For pelvis treatments, the arithmetic mean algorithm seemed unacceptable, whereas the other algorithms were satisfactory. The random error was reduced by using averaged midline doses of paired opposed portals because the asymmetric effect was averaged out. Considering the simplicity of in vivo dosimetry, the arithmetic mean and geometric mean algorithm should be adopted for head/neck and pelvis treatments, respectively.« less

Somatosensory Tinnitus: Correlation between Cranio-Cervico-Mandibular Disorder History and Somatic Modulation.

PubMed

Ralli, Massimo; Altissimi, Giancarlo; Turchetta, Rosaria; Mazzei, Filippo; Salviati, Massimo; Cianfrone, Francesca; Orlando, Maria Patrizia; Testugini, Valeria; Cianfrone, Giancarlo

2016-01-01

In a subpopulation of patients, tinnitus can be modulated by movements of the jaw or head and neck due to complex somatosensory-auditory interactions. In some of these subjects, tinnitus could be related to an underlying temporomandibular (TMJ) or craniocervical (NECK) dysfunction that, if correctly identified, could streamline treatment and increase chances of tinnitus improvement. However, it is still unclear whether somatic modulation of tinnitus could be used as a screening tool for identifying such patients. In this study, we included 310 tinnitus patients with normal hearing, no psychiatric comorbidities, and a positive history of TMJ and/or NECK dysfunction and/or a positive modulation of tinnitus to evaluate the characteristics of somatic modulation, investigate the relationship between positive history and positive modulation, and identify factors most strongly associated with somatic modulation. Tinnitus modulation was present in 79.67% of the patients. We found a significant association within the same subjects between a positive history and a positive tinnitus modulation for the same region, mainly for TMJ in unilateral tinnitus patients and for TMJ + NECK in bilateral tinnitus patients. A strong correlation between history and modulation in the same somatic region within the same subgroups of subjects was also identified. Most TMJ maneuvers resulted in an increased loudness, while NECK maneuvers showed an increase in tinnitus loudness in about 59% of cases. High-pitched tinnitus and male gender were associated with a higher prevalence of modulation; no differences were found for tinnitus onset, Tinnitus Handicap Inventory score, and age. In this paper, we report a strong association between history and modulation for the same regions within the same patients; such an association should always be investigated to improve chances of a correct diagnosis of somatosensory tinnitus. © 2017 S. Karger AG, Basel.

Comparison of image quality and radiation dose between fixed tube current and combined automatic tube current modulation in craniocervical CT angiography.

PubMed

Lee, E J; Lee, S K; Agid, R; Howard, P; Bae, J M; terBrugge, K

2009-10-01

The combined automatic tube current modulation (ATCM) technique adapts and modulates the x-ray tube current in the x-y-z axis according to the patient's individual anatomy. We compared image quality and radiation dose of the combined ATCM technique with those of a fixed tube current (FTC) technique in craniocervical CT angiography performed with a 64-section multidetector row CT (MDCT) system. A retrospective review of craniocervical CT angiograms (CTAs) by using combined ATCM (n = 25) and FTC techniques (n = 25) was performed. Other CTA parameters, such as kilovolt (peak), matrix size, FOV, section thickness, pitch, contrast agent, and contrast injection techniques, were held constant. We recorded objective image noise in the muscles at 2 anatomic levels: radiation exposure doses (CT dose index volume and dose-length product); and subjective image quality parameters, such as vascular delineation of various arterial vessels, visibility of small arterial detail, image artifacts, and certainty of diagnosis. The Mann-Whitney U test was used for statistical analysis. No significant difference was detected in subjective image quality parameters between the FTC and combined ATCM techniques. Most subjects in both study groups (49/50, 98%) had acceptable subjective artifacts. The objective image noise values at shoulder level did not show a significant difference, but the noise value at the upper neck was higher with the combined ATCM (P < .05) technique. Significant reduction in radiation dose (18% reduction) was noted with the combined ATCM technique (P < .05). The combined ATCM technique for craniocervical CTA performed at 64-section MDCT substantially reduced radiation exposure dose but maintained diagnostic image quality.

High definition video teaching module for learning neck dissection.

PubMed

Mendez, Adrian; Seikaly, Hadi; Ansari, Kal; Murphy, Russell; Cote, David

2014-03-25

Video teaching modules are proven effective tools for enhancing student competencies and technical skills in the operating room. Integration into post-graduate surgical curricula, however, continues to pose a challenge in modern surgical education. To date, video teaching modules for neck dissection have yet to be described in the literature. To develop and validate an HD video-based teaching module (HDVM) to help instruct post-graduate otolaryngology trainees in performing neck dissection. This prospective study included 6 intermediate to senior otolaryngology residents. All consented subjects first performed a control selective neck dissection. Subjects were then exposed to the video teaching module. Following a washout period, a repeat procedure was performed. Recordings of the both sets of neck dissections were de-identified and reviewed by an independent evaluator and scored using the Observational Clinical Human Reliability Assessment (OCHRA) system. In total 91 surgical errors were made prior to the HDVM and 41 after exposure, representing a 55% decrease in error occurrence. The two groups were found to be significantly different. Similarly, 66 and 24 staff takeover events occurred pre and post HDVM exposure, respectively, representing a statistically significant 64% decrease. HDVM is a useful adjunct to classical surgical training. Residents performed significantly less errors following exposure to the HD-video module. Similarly, significantly less staff takeover events occurred following exposure to the HDVM.

Dosimetric consequences of the parotid glands using CT-to-CBCT deformable registration during IMRT for late stage head and neck cancers

NASA Astrophysics Data System (ADS)

Conill, Annette L.

Patients receiving Intensity Modulated Radiation Therapy (IMRT) for late stage head and neck (HN) cancer often experience anatomical changes due to weight loss, tumor regression, and positional changes of normal anatomy (1). As a result, the actual dose delivered may vary from the original treatment plan. The purpose of this study was (a) to evaluate the dosimetric consequences of the parotid glands during the course of treatment, and (b) to determine if there would be an optimal timeframe for replanning. Nineteen locally advanced HN cancer patients underwent definitive IMRT. Each patient received an initial computerized tomography simulation (CT-SIM) scan and weekly cone beam computerized tomography (CBCT) scans. A Deformable Image Registration (DIR) was performed between the CT-SIM and CBCT of the parotid glands and Planning Target Volumes (PTVs) using the Eclipse treatment planning system (TPS) and the Velocity deformation software. A recalculation of the dose was performed on the weekly CBCTs using the original monitor units. The parameters for evaluation of our method were: the changes in volume of the PTVs and parotid glands, the dose coverage of the PTVs, the lateral displacement in the Center of Mass (COM), the mean dose, and Normal Tissue Complication Probability (NTCP) of the parotid glands. The studies showed a reduction of the volume in the PTVs and parotids, a medial displacement in COM, and alterations of the mean dose to the parotid glands as compared to the initial plans. Differences were observed for the dose volume coverage of the PTVs and NTCP of the parotid gland values between the initial plan and our proposed method utilizing deformable registration-based dose calculations.

Interpretation of Gamma Index for Quality Assurance of Simultaneously Integrated Boost (SIB) IMRT Plans for Head and Neck Carcinoma

NASA Astrophysics Data System (ADS)

Atiq, Maria; Atiq, Atia; Iqbal, Khalid; Shamsi, Quratul ain; Andleeb, Farah; Buzdar, Saeed Ahmad

2017-12-01

Objective: The Gamma Index is prerequisite to estimate point-by-point difference between measured and calculated dose distribution in terms of both Distance to Agreement (DTA) and Dose Difference (DD). This study aims to inquire what percentage of pixels passing a certain criteria assure a good quality plan and suggest gamma index as efficient mechanism for dose verification of Simultaneous Integrated Boost Intensity Modulated Radiotherapy plans. Method: In this study, dose was calculated for 14 head and neck patients and IMRT Quality Assurance was performed with portal dosimetry using the Eclipse treatment planning system. Eclipse software has a Gamma analysis function to compare measured and calculated dose distribution. Plans of this study were deemed acceptable when passing rate was 95% using tolerance for Distance to agreement (DTA) as 3mm and Dose Difference (DD) as 5%. Result and Conclusion: Thirteen cases pass tolerance criteria of 95% set by our institution. Confidence Limit for DD is 9.3% and for gamma criteria our local CL came out to be 2.0% (i.e., 98.0% passing). Lack of correlation was found between DD and γ passing rate with R2 of 0.0509. Our findings underline the importance of gamma analysis method to predict the quality of dose calculation. Passing rate of 95% is achieved in 93% of cases which is adequate level of accuracy for analyzed plans thus assuring the robustness of SIB IMRT treatment technique. This study can be extended to investigate gamma criteria of 5%/3mm for different tumor localities and to explore confidence limit on target volumes of small extent and simple geometry.

SU-E-T-268: Differences in Treatment Plan Quality and Delivery Between Two Commercial Treatment Planning Systems for Volumetric Arc-Based Radiation Therapy

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

Chen, S; Zhang, H; Zhang, B

2015-06-15

Purpose: To clinically evaluate the differences in volumetric modulated arc therapy (VMAT) treatment plan and delivery between two commercial treatment planning systems. Methods: Two commercial VMAT treatment planning systems with different VMAT optimization algorithms and delivery approaches were evaluated. This study included 16 clinical VMAT plans performed with the first system: 2 spine, 4 head and neck (HN), 2 brain, 4 pancreas, and 4 pelvis plans. These 16 plans were then re-optimized with the same number of arcs using the second treatment planning system. Planning goals were invariant between the two systems. Gantry speed, dose rate modulation, MLC modulation, planmore » quality, number of monitor units (MUs), VMAT quality assurance (QA) results, and treatment delivery time were compared between the 2 systems. VMAT QA results were performed using Mapcheck2 and analyzed with gamma analysis (3mm/3% and 2mm/2%). Results: Similar plan quality was achieved with each VMAT optimization algorithm, and the difference in delivery time was minimal. Algorithm 1 achieved planning goals by highly modulating the MLC (total distance traveled by leaves (TL) = 193 cm average over control points per plan), while maintaining a relatively constant dose rate (dose-rate change <100 MU/min). Algorithm 2 involved less MLC modulation (TL = 143 cm per plan), but greater dose-rate modulation (range = 0-600 MU/min). The average number of MUs was 20% less for algorithm 2 (ratio of MUs for algorithms 2 and 1 ranged from 0.5-1). VMAT QA results were similar for all disease sites except HN plans. For HN plans, the average gamma passing rates were 88.5% (2mm/2%) and 96.9% (3mm/3%) for algorithm 1 and 97.9% (2mm/2%) and 99.6% (3mm/3%) for algorithm 2. Conclusion: Both VMAT optimization algorithms achieved comparable plan quality; however, fewer MUs were needed and QA results were more robust for Algorithm 2, which more highly modulated dose rate.« less

SU-F-T-168: Development and Implementation of An Anthropomorphic Head & Neck Phantom for the Assessment of Proton Therapy Treatment Procedures

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

Branco, D; Taylor, P; Frank, S

2016-06-15

Purpose: To design a Head and Neck (H&N) anthropomorphic QA phantom that the Imaging and Radiation Oncology Core Houston (IROC-H) can use to verify the quality of intensity modulated proton therapy (IMPT) H&N treatments for institutions participating in NCI clinical trials. Methods: The phantom was created to serve as a remote auditing tool for IROC-H to evaluate an institution’s IMPT planning and delivery abilities. The design was based on the composition, size, and geometry of a generalized oropharyngeal tumor and contains critical structures (parotids and spinal cord). Radiochromic film in the axial and sagittal planes and thermoluminescent dosimeters (TLD)-100 capsulesmore » were embedded in the phantom and used to perform the dose delivery evaluation. A CT simulation was used to create a passive scatter and a spot scanning treatment plan with typical clinical constraints for H&N cancer. The IMPT plan was approved by a radiation oncologist and the phantom was irradiated multiple times. The measured dose distribution using a 7%/4mm gamma analysis (85% of pixels passing) and point doses were compared with the treatment planning system calculations. Results: The designed phantom could not achieve the target dose prescription and organ at risk dose constraints with the passive scatter treatment plan. The target prescription dose could be met but not the parotid dose constraint. The average TLD point dose ratio in the target was 0.975, well within the 5% acceptance criterion. The dose distribution analysis using various acceptance criteria, 5%/4mm, 5%/3mm, 7%/4mm and 7%/5mm, had average pixel passing rates of 85.9%, 81.8%, 89.6% and 91.6%, and respectively. Conclusion: An anthropomorphic IMPT H&N phantom was designed that can assess the dose delivery of proton sites wishing to participate in clinical trials using a 5% TLD dose and 7%/4mm gamma analysis acceptance criteria.« less

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

Arai, K; Tohoku University Graduate School of Medicine, Sendal, Miyagi; Kadoya, N

Purpose: The aim of this study was to confirm On-Board Imager cone-beam computed tomography (CBCT) using a histogram-matching algorithm as a useful method for proton dose calculation in head and neck radiotherapy. Methods: We studied one head and neck phantom and ten patients with head and neck cancer treated using intensity-modulated radiation therapy (IMRT) and proton beam therapy. We modified Hounsfield unit (HU) values of CBCT (mCBCT) using a histogram-matching algorithm. In order to evaluate the accuracy of the proton dose calculation, we compared dose differences in dosimetric parameters (Dmean) for clinical target volume (CTV), planning target volume (PTV) andmore » left parotid and proton ranges (PR) between the planning CT (reference) and CBCT or mCBCT, and gamma passing rates of CBCT and mCBCT. To minimize the effect of organ deformation, we also performed image registration. Results: For patients, the average differences in Dmean for CTV, PTV, and left parotid between planning CT and CBCT were 1.63 ± 2.34%, 3.30 ± 1.02%, and 5.42 ± 3.06%, respectively. Similarly, the average differences between planning CT and mCBCT were 0.20 ± 0.19%, 0.58 ±0.43%, and 3.53 ±2.40%, respectively. The average differences in PR between planning CT and CBCT or mCBCT of a 50° beam for ten patients were 2.1 ± 2.1 mm and 0.3 ± 0.5 mm, respectively. Similarly, the average differences in PR of a 120° beam were 2.9 ± 2.6 mm and 1.1 ± 0.9 mm, respectively. The average dose and PR differences of mCBCT were smaller than those of CBCT. Additionally, the average gamma passing rates of mCBCT were larger than those of CBCT. Conclusion: We evaluated the accuracy of the proton dose calculation in CBCT and mCBCT with the image registration for ten patients. Our results showed that HU modification using a histogram-matching algorithm could improve the accuracy of the proton dose calculation.« less

SU-F-J-214: Dose Reduction by Spatially Optimized Image Quality Via Fluence Modulated Proton CT (FMpCT)

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

De Angelis, L; Landry, G; Dedes, G

Purpose: Proton CT (pCT) is a promising imaging modality for reducing range uncertainty in image-guided proton therapy. Range uncertainties partially originate from X-ray CT number conversion to stopping power ratio (SPR) and are limiting the exploitation of the full potential of proton therapy. In this study we explore the concept of spatially dependent fluence modulated proton CT (FMpCT), for achieving optimal image quality in a clinical region of interest (ROI), while reducing significantly the imaging dose to the patient. Methods: The study was based on simulated ideal pCT using pencil beam (PB) scanning. A set of 250 MeV protons PBsmore » was used to create 360 projections of a cylindrical water phantom and a head and neck cancer patient. The tomographic images were reconstructed using a filtered backprojection (FBP) as well as an iterative algorithm (ITR). Different fluence modulation levels were investigated and their impact on the image was quantified in terms of SPR accuracy as well as noise within and outside selected ROIs, as a function of imaging dose. The unmodulated image served as reference. Results: Both FBP reconstruction and ITR without total variation (TV) yielded image quality in the ROIs similar to the reference images, for modulation down to 0.1 of the full proton fluence. The average dose was reduced by 75% for the water phantom and by 40% for the patient. FMpCT does not improve the noise for ITR with TV and modulation 0.1. Conclusion: This is the first work proposing and investigating FMpCT for producing optimal image quality for treatment planning and image guidance, while simultaneously reducing imaging dose. Future work will address spatial resolution effects and the impact of FMpCT on the quality of proton treatment plans for a prototype pCT scanner capable of list mode data acquisition. Acknowledgement: DFG-MAP DFG - Munich-Centre for Advanced Photonics (MAP)« less

SU-E-T-275: Radiobiological Evaluation of Intensity Modulated Radiotherapy Treatment for Locally Advanced Head and Neck Squamous Cell Carcinomas

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

Rekha Reddy, B.; Ravikumar, M.; Tanvir Pasha, C.R

2014-06-01

Purpose: To evaluate the radiobiological outcome of Intensity Modulated Radiotherapy Treatment (IMRT) for locally advanced head and neck squamous cell carcinomas using HART (Histogram Analysis in Radiation Therapy; J Appl Clin Med Phys 11(1): 137–157, 2010) program and compare with the clinical outcomes. Methods: We have treated 20 patients of stage III and IV HNSCC Oropharynx and hypopharynx with accelerated IMRT technique and concurrent chemotherapy. Delineation of tumor and normal tissues were done using Danish Head and Neck Cancer Group (DAHANCA) contouring guidelines and radiotherapy was delivered to a dose of 70Gy in 35 fractions to the primary and involvedmore » lymph nodes, 63Gy to intermediate risk areas and 56 Gy to lower risk areas, Monday to Saturday, 6 Days/week using 6 MV Photons with an expected overall treatment time of 6 weeks. The TCP and NTCP's were calculated from the dose-volume histogram (DVH) statistics using the Poisson Statistics (PS) and JT Lyman models respectively and the Resultwas correlated with clinical outcomes of the patients with mean follow up of 24 months. Results: Using HART program, the TCP (0.89± 0.01) of primary tumor and the NTCP for parotids (0.20±0.12), spinal cord (0.05±0.01), esophagus (0.30±0.2), mandible (0.35±0.21), Oral cavity (0.37±0.18), Larynx (0.30±0.15) were estimated and correlated with clinical outcome of the patients. Conclusion: Accelerated IMRT with Chemotherapy is a clinical feasible option in the treatment of locally advanced HNSCC with encouraging initial tumour response and acceptable acute toxicities. The correlation between the clinical outcomes and radiobiological model estimated parameters using HART programs are found to be satisfactory.« less

Reirradiation of Head and Neck Cancers With Intensity Modulated Radiation Therapy: Outcomes and Analyses

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

Takiar, Vinita; Garden, Adam S.; Ma, Dominic

Purpose: To review our 15-year institutional experience using intensity modulated radiation therapy (IMRT) to reirradiate patients with head and neck squamous cell carcinomas (HNSCC) and identify predictors of outcomes and toxicity. Methods and Materials: We retrospectively reviewed the records of 227 patients who received head and neck reirradiation using IMRT from 1999 to 2014. Patients treated with noncurative intent were excluded. Radiation-related acute and late toxicities were recorded. Prognostic variables included performance status, disease site, disease-free interval, chemotherapy, and RT dose and volume. Correlative analyses were performed separately for surgery and nonsurgery patients. Results: Two hundred six patients (91%) were retreatedmore » with curative intent, and 173 had HNSCC histology; 104 (50%) underwent salvage resection, and 135 (66%) received chemotherapy. Median follow-up after reirradiation was 24.7 months. Clinical outcomes were worse for HNSCC patients, with 5-year locoregional control, progression-free survival, and overall survival rates of 53%, 22%, and 32%, respectively, compared with 74%, 59%, and 79%, respectively, for non-HNSCC patients. On multivariate analysis, concurrent chemotherapy and retreatment site were associated with tumor control, whereas performance status was associated with survival. Favorable prognostic factors specific to surgery patients were neck retreatment and lack of extracapsular extension, whereas for nonsurgery patients, these were a nasopharynx subsite and complete response to induction chemotherapy. Actuarial rates of grade ≥3 toxicity were 32% at 2 years and 48% at 5 years, with dysphagia or odynophagia being most common. Increased grade ≥3 toxicity was associated with retreatment volume >50 cm{sup 3} and concurrent chemotherapy. Conclusions: Reirradiation with IMRT either definitively or after salvage surgery can produce promising local control and survival in selected patients with head and neck cancers. Treatment-related toxicity remains significant. Prognostic factors are emerging to guide multidisciplinary treatment approaches and clinical trial design.« less

SU-G-IeP2-10: Lens Dose Reduction by Patient Position Modification During Neck CT Exams

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

Mosher, E; Lee, C; Butman, J

Purpose: Irradiation of the lens during a neck CT may increase a patient’s risk of developing cataracts later in life. Radiologists and technologists at the National Institutes of Health Clinical Center (NIHCC) have developed new CT imaging protocols that include a reduction in scan range and modifying neck positioning using a head tilt. This study will evaluate the efficacy of this protocol in the reduction of lens dose. Methods: We retrieved CT images of five male patients who had two sets of CT images: before and after the implementation of the new protocol. The lens doses before the new protocolmore » were calculated using an in-house CT dose calculator, National Cancer Institute dosimetry system for CT (NCICT), where computational human phantoms with no head tilt are included. We also calculated the lens dose for the patient CT conducted after the new protocol by using an adult male computational phantom with the neck position deformed to match the angle of the head tilt. We also calculated the doses to other radiosensitive organs including the globes of the eye, brain, pituitary gland and salivary glands before and after head tilt. Results: Our dose calculations demonstrated that modifying neck position reduced dose to the lens by 89% on average (range: 86–96%). Globe, brain, pituitary and salivary gland doses also decreased by an average of 65% (51–95%), 38% (−8–66%), 34% (−43–84%) and 14% (13–14%), respectively. The new protocol resulted in a nearly ten-fold decrease in lens dose. Conclusion: The use of a head tilt and scan range reduction is an easy and effective method to reduce radiation exposure to the lens and other radiosensitive organs, while still allowing for the inclusion of critical neck structures in the CT image. We are expanding our study to a total of 10 males and 10 females.« less

Magnetic resonance imaging guided reirradiation of recurrent and second primary head and neck cancer.

PubMed

Chen, Allen M; Cao, Minsong; Hsu, Sophia; Lamb, James; Mikaeilian, Argin; Yang, Yingli; Agazaryan, Nzhde; Low, Daniel A; Steinberg, Michael L

2017-01-01

To report a single-institutional experience using magnetic resonance imaging (MRI) guided radiation therapy for the reirradiation of recurrent and second cancers of the head and neck. Between October 2014 and August 2016, 13 consecutive patients with recurrent or new primary cancers of the head and neck that occurred in a previously irradiated field were prospectively enrolled in an institutional registry trial to investigate the feasibility and efficacy of MRI guided radiation therapy using a 0.35-T MRI scanner with a cobalt-60 radiation therapy source called the ViewRay system (ViewRay Inc., Cleveland, OH). Eligibility criteria included biopsy-proven evidence of recurrent or new primary squamous cell carcinoma of the head and neck, measurable disease, and previous radiation to >60 Gy. MRI guided reirradiation was delivered either using intensity modulated radiation therapy with conventional fractionation to a median dose of 66 Gy or stereotactic body radiation therapy (SBRT) using 7 to 8 Gy fractions on nonconsecutive days to a median dose of 40 Gy. Two patients (17%) received concurrent chemotherapy. The 1- and 2-year estimates of in-field control were 72% and 72%, respectively. A total of 227 daily MRI scans were obtained to guide reirradiation. The 2-year estimates of overall survival and progression-free survival were 53% and 59%, respectively. There were no treatment-related fatalities or hospitalizations. Complications included skin desquamation, odynophagia, otitis externa, keratitis and/or conjunctivitis, and 1 case of aspiration pneumonia. Our preliminary findings show that reirradiation with MRI guided radiation therapy results in effective disease control with relatively low morbidity for patients with recurrent and second primary cancers of the head and neck. The superior soft tissue resolution of the MRI scans that were used for planning and delivery has the potential to improve the therapeutic ratio.

Quantitative evaluation of 3D dosimetry for stereotactic volumetric‐modulated arc delivery using COMPASS

PubMed Central

Manigandan, Durai; Karrthick, Karukkupalayam Palaniappan; Sambasivaselli, Raju; Senniandavar, Vellaingiri; Ramu, Mahendran; Rajesh, Thiyagarajan; Lutz, Muller; Muthukumaran, Manavalan; Karthikeyan, Nithyanantham; Tejinder, Kataria

2014-01-01

The purpose of this study was to evaluate quantitatively the patient‐specific 3D dosimetry tool COMPASS with 2D array MatriXX detector for stereotactic volumetric‐modulated arc delivery. Twenty‐five patients CT images and RT structures from different sites (brain, head & neck, thorax, abdomen, and spine) were taken from CyberKnife Multiplan planning system for this study. All these patients underwent radical stereotactic treatment in CyberKnife. For each patient, linac based volumetric‐modulated arc therapy (VMAT) stereotactic plans were generated in Monaco TPS v3.1 using Elekta Beam Modulator MLC. Dose prescription was in the range of 5–20 Gy per fraction. Target prescription and critical organ constraints were tried to match the delivered treatment plans. Each plan quality was analyzed using conformity index (CI), conformity number (CN), gradient Index (GI), target coverage (TC), and dose to 95% of volume (D95). Monaco Monte Carlo (MC)‐calculated treatment plan delivery accuracy was quantitatively evaluated with COMPASS‐calculated (CCA) dose and COMPASS indirectly measured (CME) dose based on dose‐volume histogram metrics. In order to ascertain the potential of COMPASS 3D dosimetry for stereotactic plan delivery, 2D fluence verification was performed with MatriXX using MultiCube phantom. Routine quality assurance of absolute point dose verification was performed to check the overall delivery accuracy. Quantitative analyses of dose delivery verification were compared with pass and fail criteria of 3 mm and 3% distance to agreement and dose differences. Gamma passing rate was compared with 2D fluence verification from MatriXX with MultiCube. Comparison of COMPASS reconstructed dose from measured fluence and COMPASS computed dose has shown a very good agreement with TPS calculated dose. Each plan was evaluated based on dose volume parameters for target volumes such as dose at 95% of volume (D95) and average dose. For critical organs dose at 20% of volume (D20), dose at 50% of volume (D50), and maximum point doses were evaluated. Comparison was carried out using gamma analysis with passing criteria of 3 mm and 3%. Mean deviation of 1.9%±1% was observed for dose at 95% of volume (D95) of target volumes, whereas much less difference was noticed for critical organs. However, significant dose difference was noticed in two cases due to the smaller tumor size. Evaluation of this study revealed that the COMPASS 3D dosimetry is efficient and easy to use for patient‐specific QA of VMAT stereotactic delivery. 3D dosimetric QA with COMPASS provides additional degrees of freedom to check the high‐dose modulated stereotactic delivery with very high precision on patient CT images. PACS numbers: 87.55.Qr, 87.56.Fc PMID:25679152

Real-time in vivo dosimetry with MOSFET detectors in serial tomotherapy for head and neck cancer patients.

PubMed

Qi, Zhen-Yu; Deng, Xiao-Wu; Huang, Shao-Min; Shiu, Almon; Lerch, Michael; Metcalfe, Peter; Rosenfeld, Anatoly; Kron, Tomas

2011-08-01

A real-time dose verification method using a recently designed metal oxide semiconductor field effect transistor (MOSFET) dosimetry system was evaluated for quality assurance (QA) of intensity-modulated radiation therapy (IMRT). Following the investigation of key parameters that might affect the accuracy of MOSFET measurements (i.e., source surface distance [SSD], field size, beam incident angles and radiation energy spectrum), the feasibility of this detector in IMRT dose verification was demonstrated by comparison with ion chamber measurements taken in an IMRT QA phantom. Real-time in vivo measurements were also performed with the MOSFET system during serial tomotherapy treatments administered to 8 head and neck cancer patients. MOSFET sensitivity did not change with SSD. For field sizes smaller than 20 × 20 cm(2), MOFET sensitivity varied within 1.0%. The detector angular response was isotropic within 2% over 360°, and the observed sensitivity variation due to changes in the energy spectrum was negligible in 6-MV photons. MOSFET system measurements and ion chamber measurements agreed at all points in IMRT phantom plan verification, within 5%. The mean difference between 48 IMRT MOSFET-measured doses and calculated values in 8 patients was 3.33% and ranged from -2.20% to 7.89%. More than 90% of the total measurements had deviations of less than 5% from the planned doses. The MOSFET dosimetry system has been proven to be an effective tool in evaluating the actual dose within individual patients during IMRT treatment. Copyright © 2011 Elsevier Inc. All rights reserved.

Lethal visceral traumatic injuries secondary to child abuse: a case of practical application of autopsy, radiological and microscopic studies.

PubMed

Dedouit, Fabrice; Mallinger, Béatrice; Guilbeau-Frugier, Céline; Rougé, Daniel; Rousseau, Hervé; Telmon, Norbert

2011-03-20

A 3-year-old boy child died at home. The circumstances of death appeared unclear to the police investigators and a medicolegal autopsy was carried out. External examination revealed diffuse ecchymoses of varying colours. Postmortem imaging using plain X-rays and multislice computed tomography (MSCT) was performed prior to autopsy and pathological study. These investigations revealed fractures at the posterior arch of the ninth left rib. No cerebral and pericerebral traumatic lesions were diagnosed. In the abdomen, haemoperitoneum and pneumoperitoneum secondary to duodenal perforation and liver laceration were observed. At autopsy, a complete pancreatic fracture and duodenal transection were noted, accounting for the MSCT appearance. Furthermore, autopsy revealed the presence of bilateral intramuscular intercostal haemorrhages and a fracture of the eighth left rib at its posterior arch. This case report illustrates the valuable assistance rendered by MSCT as well as its limitations in diagnosing abuse when a child dies in unclear circumstances. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Application of multislice spiral CT for guidance of insertion of thoracic spine pedicle screws: an in vitro study.

PubMed

Wang, Juan; Zhou, Yicheng; Hu, Ning; Wang, Renfa

2006-01-01

To investigate the value of the guidance of three dimensional (3-D) reconstruction of multi-slice spiral CT (MSCT) for the placement of pedicle screws, the 3-D anatomical data of the thoracic pedicles were measured by MSCT in two embalmed human cadaveric thoracic pedicles spines (T1-T10) to guide the insertion of pedicle screws. After pulling the screws out, the pathways were filled with contrast media. The PW, PH, TSA and SSA of developed pathways were measured on the CT images and they were also measured on the real objects by caliper and goniometer. Analysis of variance demonstrated that the difference between the CT scans and real objects had no statistical significance (P > 0.05). Moreover, the difference between pedicle axis and developed pathway also had no statistical significance (P > 0.05). The data obtained from 3-D reconstruction of MSCT demonstrated that individualized standards, are not only accurate but also helpful for the successful placement of pedicle screws.

Detection of IMRT delivery errors based on a simple constancy check of transit dose by using an EPID

NASA Astrophysics Data System (ADS)

Baek, Tae Seong; Chung, Eun Ji; Son, Jaeman; Yoon, Myonggeun

2015-11-01

Beam delivery errors during intensity modulated radiotherapy (IMRT) were detected based on a simple constancy check of the transit dose by using an electronic portal imaging device (EPID). Twenty-one IMRT plans were selected from various treatment sites, and the transit doses during treatment were measured by using an EPID. Transit doses were measured 11 times for each course of treatment, and the constancy check was based on gamma index (3%/3 mm) comparisons between a reference dose map (the first measured transit dose) and test dose maps (the following ten measured dose maps). In a simulation using an anthropomorphic phantom, the average passing rate of the tested transit dose was 100% for three representative treatment sites (head & neck, chest, and pelvis), indicating that IMRT was highly constant for normal beam delivery. The average passing rate of the transit dose for 1224 IMRT fields from 21 actual patients was 97.6% ± 2.5%, with the lower rate possibly being due to inaccuracies of patient positioning or anatomic changes. An EPIDbased simple constancy check may provide information about IMRT beam delivery errors during treatment.

Transit dosimetry in IMRT with an a-Si EPID in direct detection configuration

NASA Astrophysics Data System (ADS)

Sabet, Mahsheed; Rowshanfarzad, Pejman; Vial, Philip; Menk, Frederick W.; Greer, Peter B.

2012-08-01

In this study an amorphous silicon electronic portal imaging device (a-Si EPID) converted to direct detection configuration was investigated as a transit dosimeter for intensity modulated radiation therapy (IMRT). After calibration to dose and correction for a background offset signal, the EPID-measured absolute IMRT transit doses for 29 fields were compared to a MatriXX two-dimensional array of ionization chambers (as reference) using Gamma evaluation (3%, 3 mm). The MatriXX was first evaluated as reference for transit dosimetry. The accuracy of EPID measurements was also investigated by comparison of point dose measurements by an ionization chamber on the central axis with slab and anthropomorphic phantoms in a range of simple to complex fields. The uncertainty in ionization chamber measurements in IMRT fields was also investigated by its displacement from the central axis and comparison with the central axis measurements. Comparison of the absolute doses measured by the EPID and MatriXX with slab phantoms in IMRT fields showed that on average 96.4% and 97.5% of points had a Gamma index<1 in head and neck and prostate fields, respectively. For absolute dose comparisons with anthropomorphic phantoms, the values changed to an average of 93.6%, 93.7% and 94.4% of points with Gamma index<1 in head and neck, brain and prostate fields, respectively. Point doses measured by the EPID and ionization chamber were within 3% difference for all conditions. The deviations introduced in the response of the ionization chamber in IMRT fields were<1%. The direct EPID performance for transit dosimetry showed that it has the potential to perform accurate, efficient and comprehensive in vivo dosimetry for IMRT.

Three-dimensional cluster formation and structure in heterogeneous dose distribution of intensity modulated radiation therapy.

PubMed

Chao, Ming; Wei, Jie; Narayanasamy, Ganesh; Yuan, Yading; Lo, Yeh-Chi; Peñagarícano, José A

2018-05-01

To investigate three-dimensional cluster structure and its correlation to clinical endpoint in heterogeneous dose distributions from intensity modulated radiation therapy. Twenty-five clinical plans from twenty-one head and neck (HN) patients were used for a phenomenological study of the cluster structure formed from the dose distributions of organs at risks (OARs) close to the planning target volumes (PTVs). Initially, OAR clusters were searched to examine the pattern consistence among ten HN patients and five clinically similar plans from another HN patient. Second, clusters of the esophagus from another ten HN patients were scrutinized to correlate their sizes to radiobiological parameters. Finally, an extensive Monte Carlo (MC) procedure was implemented to gain deeper insights into the behavioral properties of the cluster formation. Clinical studies showed that OAR clusters had drastic differences despite similar PTV coverage among different patients, and the radiobiological parameters failed to positively correlate with the cluster sizes. MC study demonstrated the inverse relationship between the cluster size and the cluster connectivity, and the nonlinear changes in cluster size with dose thresholds. In addition, the clusters were insensitive to the shape of OARs. The results demonstrated that the cluster size could serve as an insightful index of normal tissue damage. The clinical outcome of the same dose-volume might be potentially different. Copyright © 2018 Elsevier B.V. All rights reserved.

SU-F-J-48: Effect of Scan Length On Magnitude of Imaging Dose in KV CBCT

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

Deshpande, S; Naidu, S; Sutar, A

Purpose: To study effect of scan length on magnitude of imaging dose deposition in Varian kV CBCT for head & neck and pelvis CBCT. Methods: To study effect of scan length we measured imaging dose at depth of 8 cm for head and neck Cone Beam Computed Tomography (CBCT) acquisition ( X ray beam energy is used 100kV and 200 degree of gantry rotation) and at 16 cm depth for pelvis CBCT acquisition ( X ray beam energy used is 125 kV and 360 degree of gantry rotation) in specially designed phantom. We used farmer chamber which was calibrated inmore » kV X ray range for measurements .Dose was measured with default field size, and reducing field size along y direction to 10 cm and 5 cm. Results: As the energy of the beam decreases the scattered radiation increases and this contributes significantly to the dose deposited in the patient. By reducing the scan length to 10 Cm from default 20.6 cm we found a dose reduction of 14% for head and neck CBCT protocol and a reduction of 26% for pelvis CBCT protocol. Similarly for a scan length of 5cm compared to default the dose reduction in head and neck CBCT protocol is 36% while in the pelvis CBCT protocol the dose reduction is 50%. Conclusion: By limiting the scan length we can control the scatter radiation generated and hence the dose to the patient. However the variation in dose reduction for same length used in two protocols is because of the scan geometry. The pelvis CBCT protocol uses a full rotation and head and neck CBCT protocol uses partial rotation.« 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.

FDG-PET Assessment of the Effect of Head and Neck Radiotherapy on Parotid Gland Glucose Metabolism

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

Roach, Michael C.; Turkington, Timothy G.; Department of Biomedical Engineering, Duke University Medical Center, Duke University, Durham, NC

Purpose: Functional imaging with [F-18]-fluorodeoxyglucose positron emission tomography (FDG-PET) provides the opportunity to define the physiology of the major salivary glands before and after radiation therapy. The goal of this retrospective study was to identify the radiation dose-response relationship of parotid gland glucose metabolism in patients with head and neck squamous cell carcinoma (HNSCC). Materials and Methods: Forty-nine adults with HNSCC were identified who had curative intent intensity-modulated radiation therapy (IMRT) and FDG-PET imaging before and after treatment. Using a graphical user interface, contours were delineated for the parotid glands on axial CT slices while all authors were blinded tomore » paired PET slices. Average and maximal standard uptake values (SUV) were measured within these anatomic regions. Changes in SUV and volume after radiation therapy were correlated with parotid gland dose-volume histograms from IMRT plans. Results: The average parotid gland volume was 30.7 mL and contracted 3.9 {+-} 1.9% with every increase of 10 Gy in mean dose (p = 0.04). However, within the first 3 months after treatment, there was a uniform reduction of 16.5% {+-} 7.3% regardless of dose. The average SUV{sub mean} of the glands was 1.63 {+-} 0.48 pretreatment and declined by 5.2% {+-} 2.5% for every increase of 10 Gy in mean dose (p = 0.04). The average SUV{sub max} was 4.07 {+-} 2.85 pretreatment and decreased in a sigmoid manner with mean dose. A threshold of 32 Gy for mean dose existed, after which SUV{sub max} declined rapidly. Conclusion: Radiation dose responses of the parotid glands can be measured by integrated CT/FDG-PET scans. Retrospective analysis showed sigmoidal declines in the maximum metabolism but linear declines in the average metabolism of the glands with dose. Future studies should correlate this decline in FDG uptake with saliva production to improve treatment planning.« less

Volumetric modulated arc therapy: a review of current literature and clinical use in practice

PubMed Central

Teoh, M; Clark, C H; Wood, K; Whitaker, S; Nisbet, A

2011-01-01

Volumetric modulated arc therapy (VMAT) is a novel radiation technique, which can achieve highly conformal dose distributions with improved target volume coverage and sparing of normal tissues compared with conventional radiotherapy techniques. VMAT also has the potential to offer additional advantages, such as reduced treatment delivery time compared with conventional static field intensity modulated radiotherapy (IMRT). The clinical worldwide use of VMAT is increasing significantly. Currently the majority of published data on VMAT are limited to planning and feasibility studies, although there is emerging clinical outcome data in several tumour sites. This article aims to discuss the current use of VMAT techniques in practice and review the available data from planning and clinical outcome studies in various tumour sites including prostate, pelvis (lower gastrointestinal, gynaecological), head and neck, thoracic, central nervous system, breast and other tumour sites. PMID:22011829

Evaluation of a software module for adaptive treatment planning and re-irradiation.

PubMed

Richter, Anne; Weick, Stefan; Krieger, Thomas; Exner, Florian; Kellner, Sonja; Polat, Bülent; Flentje, Michael

2017-12-28

The aim of this work is to validate the Dynamic Planning Module in terms of usability and acceptance in the treatment planning workflow. The Dynamic Planning Module was used for decision making whether a plan adaptation was necessary within one course of radiation therapy. The Module was also used for patients scheduled for re-irradiation to estimate the dose in the pretreated region and calculate the accumulated dose to critical organs at risk. During one year, 370 patients were scheduled for plan adaptation or re-irradiation. All patient cases were classified according to their treated body region. For a sub-group of 20 patients treated with RT for lung cancer, the dosimetric effect of plan adaptation during the main treatment course was evaluated in detail. Changes in tumor volume, frequency of re-planning and the time interval between treatment start and plan adaptation were assessed. The Dynamic Planning Tool was used in 20% of treated patients per year for both approaches nearly equally (42% plan adaptation and 58% re-irradiation). Most cases were assessed for the thoracic body region (51%) followed by pelvis (21%) and head and neck cases (10%). The sub-group evaluation showed that unintended plan adaptation was performed in 38% of the scheduled cases. A median time span between first day of treatment and necessity of adaptation of 17 days (range 4-35 days) was observed. PTV changed by 12 ± 12% on average (maximum change 42%). PTV decreased in 18 of 20 cases due to tumor shrinkage and increased in 2 of 20 cases. Re-planning resulted in a reduction of the mean lung dose of the ipsilateral side in 15 of 20 cases. The experience of one year showed high acceptance of the Dynamic Planning Module in our department for both physicians and medical physicists. The re-planning can potentially reduce the accumulated dose to the organs at risk and ensure a better target volume coverage. In the re-irradiation situation, the Dynamic Planning Tool was used to consider the pretreatment dose, to adapt the actual treatment schema more specifically and to review the accumulated dose.

WE-E-BRE-09: Investigation of the Association Between Radiation-Induced Pain and Radiation Dose in Head and Neck Cancer Patients

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

Gay, H; Dyk, P; Mullen, D

Purpose: Patients with head and neck cancer who undergo radiotherapy often experience several undesirable side-effects, including xerostomia, trismus, and pain in the head and neck area, but little is know about the dose-volume predictors of such pain. We investigated the association between radiation dose and both throat and esophagus pain during radiotherapy. Methods: We analyzed 124 head and neck patients who received radiotherapy at the Washington University School of Medicine in Saint Louis. For these patients, weekly PROs were recorded, including 16 pain and anatomical location questions. In addition, 17 observational symptoms were recorded. Patients were asked to describe theirmore » pain at each site according to a four-level scale: none (0), mild (1), moderate (2), and severe (3). We explored the association between throat pain and the mean dose received in oral cavity and between esophageal pain and the mean dose received in the esophagus. The severity of pain was determined by the difference between the baseline (week 1) pain score and the maximum pain score during treatment. The baseline pain score was defined as the first available pain score before receiving 10 Gy because radiotherapy pain originates later during treatment. Dose-volume metrics were extracted from treatment plans using CERR. To evaluate the correlation between pain and radiation dose, Spearman's correlation coefficient (Rs) was used. Results: The associations between throat pain and the mean dose to the oral cavity, and between esophagus pain and the mean dose to the esophagus, were both statistically significant, with Rs=0.320 (p=0.003) and Rs=0.424 (p<0.0001), respectively. Mean dose, for each structure, was a better predictor of pain than total integral dose. Conclusion: We demonstrated that pain during radiotherapy in head and neck patients highly correlates with the dose delivered. We will further investigate the association between other pain locations and relevant normal tissue dose characteristics.« less

Comparison of selected dose calculation algorithms in radiotherapy treatment planning for tissues with inhomogeneities

NASA Astrophysics Data System (ADS)

Woon, Y. L.; Heng, S. P.; Wong, J. H. D.; Ung, N. M.

2016-03-01

Inhomogeneity correction is recommended for accurate dose calculation in radiotherapy treatment planning since human body are highly inhomogeneous with the presence of bones and air cavities. However, each dose calculation algorithm has its own limitations. This study is to assess the accuracy of five algorithms that are currently implemented for treatment planning, including pencil beam convolution (PBC), superposition (SP), anisotropic analytical algorithm (AAA), Monte Carlo (MC) and Acuros XB (AXB). The calculated dose was compared with the measured dose using radiochromic film (Gafchromic EBT2) in inhomogeneous phantoms. In addition, the dosimetric impact of different algorithms on intensity modulated radiotherapy (IMRT) was studied for head and neck region. MC had the best agreement with the measured percentage depth dose (PDD) within the inhomogeneous region. This was followed by AXB, AAA, SP and PBC. For IMRT planning, MC algorithm is recommended for treatment planning in preference to PBC and SP. The MC and AXB algorithms were found to have better accuracy in terms of inhomogeneity correction and should be used for tumour volume within the proximity of inhomogeneous structures.

Optimization in Radiation Therapy: Applications in Brachytherapy and Intensity Modulated Radiation Therapy

NASA Astrophysics Data System (ADS)

McGeachy, Philip David

Over 50% of cancer patients require radiation therapy (RT). RT is an optimization problem requiring maximization of the radiation damage to the tumor while minimizing the harm to the healthy tissues. This dissertation focuses on two main RT optimization problems: 1) brachytherapy and 2) intensity modulated radiation therapy (IMRT). The brachytherapy research involved solving a non-convex optimization problem by creating an open-source genetic algorithm optimizer to determine the optimal radioactive seed distribution for a given set of patient volumes and constraints, both dosimetric- and implant-based. The optimizer was tested for a set of 45 prostate brachytherapy patients. While all solutions met the clinical standards, they also benchmarked favorably with those generated by a standard commercial solver. Compared to its compatriot, the salient features of the generated solutions were: slightly reduced prostate coverage, lower dose to the urethra and rectum, and a smaller number of needles required for an implant. Historically, IMRT requires modulation of fluence while keeping the photon beam energy fixed. The IMRT-related investigation in this thesis aimed at broadening the solution space by varying photon energy. The problem therefore involved simultaneous optimization of photon beamlet energy and fluence, denoted by XMRT. Formulating the problem as convex, linear programming was applied to obtain solutions for optimal energy-dependent fluences, while achieving all clinical objectives and constraints imposed. Dosimetric advantages of XMRT over single-energy IMRT in the improved sparing of organs at risk (OARs) was demonstrated in simplified phantom studies. The XMRT algorithm was improved to include clinical dose-volume constraints and clinical studies for prostate and head and neck cancer patients were investigated. Compared to IMRT, XMRT provided improved dosimetric benefit in the prostate case, particularly within intermediate- to low-dose regions (≤ 40 Gy) for OARs. For head and neck cases, XMRT solutions showed no significant disadvantage or advantage over IMRT. The deliverability concerns for the fluence maps generated from XMRT were addressed by incorporating smoothing constraints during the optimization and through successful generation of treatment machine files. Further research is needed to explore the full potential of the XMRT approach to RT.

Changes in salivary gland function after radiotherapy of head and neck tumors measured by quantitative pertechnetate scintigraphy: Comparison of intensity-modulated radiotherapy and conventional radiation therapy with and without Amifostine

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

Muenter, Marc W.; Hoffner, Simone; Department of Nuclear Medicine, University of Heidelberg, Heidelberg

2007-03-01

Purpose: The aim of this study was to compare changes in salivary gland function after intensity-modulated radiotherapy (IMRT) and conventional radiotherapy (RT), with or without Amifostine, for tumors of the head-and-neck region using quantitative salivary gland scintigraphy (QSGS). Methods and Materials: A total of 75 patients received pre- and post-therapeutic QSGS to quantify the salivary gland function. In all, 251 salivary glands were independently evaluated. Changes in the maximum uptake ({delta}U) and relative excretion rate ({delta}F) both pre- and post-RT were determined to characterize radiation-induced changes in the salivary gland function. In addition, dose-response curves were calculated. Results: In allmore » groups, maximum uptake and relative excretion rate were reduced after RT ({delta}U {<=}0 and {delta}F {<=}0). The reduction was significantly lower for IMRT than for conventional RT. For the parotid glands, the reduction was smaller for the IMRT-low than for the IMRT-high group. For the Amifostine-high and the conventional group the difference was significant only for one parameter ({delta}U, parotid and submandibular glands, p < 0.05). In contrast to this, the difference between the Amifostine-low and the conventional group was always significant or at least showed a clear trend for both changes in U and F. In regard to the endpoint 'reduction of the salivary gland excretion rate of more than 50%,' the dose-response curves yielded D{sub 50}-values of 34.2 {+-} 12.2 Gy for the conventionally treated group and 36.8 {+-} 2.9 Gy for the IMRT group. For the Amifostine group, an increased D{sub 50}-values of 46.3 {+-} 2.3 Gy was obtained. Conclusion: Intensity-modulated RT can significantly reduce the loss of parotid gland function when respecting a certain dose threshold. Conventional RT plus Amifostine prevents reduced salivary gland function only in the patient group treated with <40.6 Gy.« less

Commissioning of intensity modulated neutron radiotherapy (IMNRT).

PubMed

Burmeister, Jay; Spink, Robyn; Liang, Liang; Bossenberger, Todd; Halford, Robert; Brandon, John; Delauter, Jonathan; Snyder, Michael

2013-02-01

Intensity modulated neutron radiotherapy (IMNRT) has been developed using inhouse treatment planning and delivery systems at the Karmanos Cancer Center∕Wayne State University Fast Neutron Therapy facility. The process of commissioning IMNRT for clinical use is presented here. Results of commissioning tests are provided including validation measurements using representative patient plans as well as those from the TG-119 test suite. IMNRT plans were created using the Varian Eclipse optimization algorithm and an inhouse planning system for calculation of neutron dose distributions. Tissue equivalent ionization chambers and an ionization chamber array were used for point dose and planar dose distribution comparisons with calculated values. Validation plans were delivered to water and virtual water phantoms using TG-119 measurement points and evaluation techniques. Photon and neutron doses were evaluated both inside and outside the target volume for a typical IMNRT plan to determine effects of intensity modulation on the photon dose component. Monitor unit linearity and effects of beam current and gantry angle on output were investigated, and an independent validation of neutron dosimetry was obtained. While IMNRT plan quality is superior to conventional fast neutron therapy plans for clinical sites such as prostate and head and neck, it is inferior to photon IMRT for most TG-119 planning goals, particularly for complex cases. This results significantly from current limitations on the number of segments. Measured and calculated doses for 11 representative plans (six prostate∕five head and neck) agreed to within -0.8 ± 1.4% and 5.0 ± 6.0% within and outside the target, respectively. Nearly all (22∕24) ion chamber point measurements in the two phantom arrangements were within the respective confidence intervals for the quantity [(measured-planned)∕prescription dose] derived in TG-119. Mean differences for all measurements were 0.5% (max = 7.0%) and 1.4% (max = 4.1%) in water and virtual water, respectively. The mean gamma pass rate for all cases was 92.8% (min = 88.6%). These pass rates are lower than typically achieved with photon IMRT, warranting development of a planar dosimetry system designed specifically for IMNRT and∕or the improvement of neutron beam modeling in the penumbral region. The fractional photon dose component did not change significantly in a typical IMNRT plan versus a conventional fast neutron therapy plan, and IMNRT delivery is not expected to significantly alter the RBE. All other commissioning results were considered satisfactory for clinical implementation of IMNRT, including the external neutron dose validation, which agreed with the predicted neutron dose to within 1%. IMNRT has been successfully commissioned for clinical use. While current plan quality is inferior to photon IMRT, it is superior to conventional fast neutron therapy. Ion chamber validation results for IMNRT commissioning are also comparable to those typically achieved with photon IMRT. Gamma pass rates for planar dose distributions are lower than typically observed for photon IMRT but may be improved with improved planar dosimetry equipment and beam modeling techniques. In the meantime, patient-specific quality assurance measurements should rely more heavily on point dose measurements with tissue equivalent ionization chambers. No significant technical impediments are anticipated in the clinical implementation of IMNRT as described here.

Dosimetric and radiobiological comparison of Forward Tangent Intensity Modulated Radiation Therapy (FT-IMRT) and Volumetric Modulated Arc Therapy (VMAT) for early stage whole breast cancer

NASA Astrophysics Data System (ADS)

Moshiri Sedeh, Nader

Intensity Modulated Radiation Therapy (IMRT) is a well-known type of external beam radiation therapy. The advancement in technology has had an inevitable influence in radiation oncology as well that has led to a newer and faster dose delivery technique called Volumetric Modulated Arc Therapy (VMAT). Since the presence of the VMAT modality in clinics in the late 2000, there have been many studies in order to compare the results of the VMAT modality with the current popular modality IMRT for various tumor sites in the body such as brain, prostate, head and neck, cervix and anal carcinoma. This is the first study to compare VMAT with IMRT for breast cancer. The results show that the RapidArc technique in Eclipse version 11 does not improve all aspects of the treatment plans for the breast cases automatically and easily, but it needs to be manipulated by extra techniques to create acceptable plans thus further research is needed.

Dosimetric effect of limited aperture multileaf collimator on VMAT plan quality: A study of prostate and head-and-neck cancers.

PubMed

Murtaza, Ghulam; Mehmood, Shahid; Rasul, Shahid; Murtaza, Imran; Khan, Ehsan Ullah

2018-01-01

The aim of study was to evaluate the dosimetric effect of collimator-rotation on VMAT plan quality, when using limited aperture multileaf collimator of Elekta Beam Modulator™ providing a maximum aperture of 21 cm × 16 cm. The increased use of VMAT technique to deliver IMRT from conventional to very specialized treatments present a challenge in plan optimization. In this study VMAT plans were optimized for prostate and head and neck cancers using Elekta Beam-Modulator TM , whereas previous studies were reported for conventional Linac aperture. VMAT plans for nine of each prostate and head-and-neck cancer patients were produced using the 6 MV photon beam for Elekta-SynergyS ® Linac using Pinnacle 3 treatment planning system. Single arc, dual arc and two combined independent-single arcs were optimized for collimator angles (C) 0°, 90° and 0°-90° (0°-90°; i.e. the first-arc was assigned C0° and second-arc was assigned C90°). A treatment plan comparison was performed among C0°, C90° and C(0°-90°) for single-arc dual-arc and two independent-single-arcs VMAT techniques to evaluate the influence of extreme collimator rotations (C0° and 90°) on VMAT plan quality. Plan evaluation criteria included the target coverage, conformity index, homogeneity index and doses to organs at risk. A 'two-sided student t -test' ( p  ≤ 0.05) was used to determine if there was a significant difference in dose volume indices of plans. For both prostate and head-and-neck, plan quality at collimator angles C0° and C(0°-90°) was clinically acceptable for all VMAT-techniques, except SA for head-and-neck. Poorer target coverage, higher normal tissue doses and significant p -values were observed for collimator angle 90° when compared with C0° and C(0°-90°). A collimator rotation of 0° provided significantly better target coverage and sparing of organs-at-risk than a collimator rotation of 90° for all VMAT techniques.

[Design and accuracy analysis of upper slicing system of MSCT].

PubMed

Jiang, Rongjian

2013-05-01

The upper slicing system is the main components of the optical system in MSCT. This paper focuses on the design of upper slicing system and its accuracy analysis to improve the accuracy of imaging. The error of slice thickness and ray center by bearings, screw and control system were analyzed and tested. In fact, the accumulated error measured is less than 1 microm, absolute error measured is less than 10 microm. Improving the accuracy of the upper slicing system contributes to the appropriate treatment methods and success rate of treatment.

Implications of improved diagnostic imaging of small nodal metastases in head and neck cancer: Radiotherapy target volume transformation and dose de-escalation.

PubMed

van den Bosch, Sven; Vogel, Wouter V; Raaijmakers, Cornelis P; Dijkema, Tim; Terhaard, Chris H J; Al-Mamgani, Abrahim; Kaanders, Johannes H A M

2018-05-03

Diagnostic imaging continues to evolve, and now has unprecedented accuracy for detecting small nodal metastasis. This influences the tumor load in elective target volumes and subsequently has consequences for the radiotherapy dose required to control disease in these volumes. Small metastases that used to remain subclinical and were included in elective volumes, will nowadays be detected and included in high-dose volumes. Consequentially, high-dose volumes will more often contain low-volume disease. These target volume transformations lead to changes in the tumor burden in elective and "gross" tumor volumes with implications for the radiotherapy dose prescribed to these volumes. For head and neck tumors, nodal staging has evolved from mere palpation to combinations of high-resolution imaging modalities. A traditional nodal gross tumor volume in the neck typically had a minimum diameter of 10-15 mm, while nowadays much smaller tumor deposits are detected in lymph nodes. However, the current dose levels for elective nodal irradiation were empirically determined in the 1950s, and have not changed since. In this report the radiobiological consequences of target volume transformation caused by modern imaging of the neck are evaluated, and theoretically derived reductions of dose in radiotherapy for head and neck cancer are proposed. The concept of target volume transformation and subsequent strategies for dose adaptation applies to many other tumor types as well. Awareness of this concept may result in new strategies for target definition and selection of dose levels with the aim to provide optimal tumor control with less toxicity. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

The impacts of dental filling materials on RapidArc treatment planning and dose delivery: Challenges and solution

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

Mail, Noor; Al-Ghamdi, S.; Saoudi, A.

Purpose: The presence of high-density material in the oral cavity creates dose perturbation in both downstream and upstream directions at the surfaces of dental filling materials (DFM). In this study, the authors have investigated the effect of DFM on head and neck RapidArc treatment plans and delivery. Solutions are proposed to address (1) the issue of downstream dose perturbation, which might cause target under dosage, and (2) to reduce the upstream dose from DFM which may be the primary source of mucositis. In addition, an investigation of the clinical role of a custom-made plastic dental mold/gutter (PDM) in sparing themore » oral mucosa and tongue reaction is outlined.Methods: The influence of the dental filling artifacts on dose distribution was investigated using a geometrically well-defined head and neck intensity modulated radiation therapy (IMRT) verification phantom (PTW, Freiberg, Germany) with DFM inserts called amalgam, which contained 50% mercury, 25% silver, 14% tin, 8% copper, and 3% other trace metals. Three RapidArc plans were generated in the Varian Eclipse System to treat the oral cavity using the same computer tomography (CT) dataset, including (1) a raw CT image, (2) a streaking artifacts region, which was replaced with a mask of 10 HU, and (3) a 2 cm-thick 6000 HU virtual filter [a volume created in treatment planning system to compensate for beam attenuation, where the thickness of this virtual filter is based on the measured percent depth dose (PDD) data and Eclipse calculation]. The dose delivery for the three plans was verified using Gafchromic-EBT2 film measurements. The custom-made PDM technique to reduce backscatter dose was clinically tested on four head and neck cancer patients (T3, N1, M0) with DFM, two patients with PDM and the other two patients without PDM. The thickness calculation of the PDM toward the mucosa and tongue was purely based on the measured upstream dose. Patients’ with oral mucosal reaction was clinically examined initially and weekly during the course of radiotherapy.Results: For a RapidArc treatment technique, the backscatter dose from the DFM insert was measured to be 9.25 ± 2.17 in the IMRT-verification-phantom. The measured backscatter upstream dose from DFM for a single-field was 22% higher than without the DFM, whereas the downstream dose was lower by 14%. The values of homogeneity index for the plans with and without the application of mask were 0.09 and 0.14, respectively. The calculated mean treatment planning volume (PTV) dose differed from the delivered dose by 13% and was reduced to 2% when using the mask and virtual filter together. A grade 3 mucosa reaction was observed in the control group after 22–24 fractions (44–48 Gy). In contrast, no grade 3 mucositis was observed in the patients wearing the PDM after 25–26 fractions (50–52 Gy).Conclusions: The backscatter from the DFM for a single, parallel-opposed fields, and RapidArc treatment technique was found significant. The application of mask in replacing streaking artifacts can be useful in improving dose homogeneity in the PTV. The use of a virtual filter around the teeth during the planning phase reduces the target underdosage issue in the phantom. Furthermore, a reduction in mucositis is observed in the head and neck patients with the use of PDM.« less

Intensity-Modulated Radiotherapy of Head and Neck Cancer Aiming to Reduce Dysphagia: Early Dose-Effect Relationships for the Swallowing Structures

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

Feng, Felix Y.; Kim, Hyungjin M.; Lyden, Teresa H.

2007-08-01

Purpose: To present initial results of a clinical trial of intensity-modulated radiotherapy (IMRT) aiming to spare the swallowing structures whose dysfunction after chemoradiation is a likely cause of dysphagia and aspiration, without compromising target doses. Methods and Materials: This was a prospective, longitudinal study of 36 patients with Stage III-IV oropharyngeal (31) or nasopharyngeal (5) cancer. Definitive chemo-IMRT spared salivary glands and swallowing structures: pharyngeal constrictors (PC), glottic and supraglottic larynx (GSL), and esophagus. Lateral but not medial retropharyngeal nodes were considered at risk. Dysphagia endpoints included objective swallowing dysfunction (videofluoroscopy), and both patient-reported and observer-rated scores. Correlations between dosesmore » and changes in these endpoints from pre-therapy to 3 months after therapy were assessed. Results: Significant correlations were observed between videofluoroscopy-based aspirations and the mean doses to the PC and GSL, as well as the partial volumes of these structures receiving 50-65 Gy; the highest correlations were associated with doses to the superior PC (p = 0.005). All patients with aspirations received mean PC doses >60 Gy or PC V{sub 65} >50%, and GSL V{sub 50} >50%. Reduced laryngeal elevation and epiglottic inversion were correlated with mean PC and GSL doses (p < 0.01). All 3 patients with strictures had PC V{sub 70} >50%. Worsening patient-reported liquid swallowing was correlated with mean PC (p = 0.05) and esophageal (p 0.02) doses. Only mean PC doses were correlated with worsening patient-reported solid swallowing (p = 0.04) and observer-rated swallowing scores (p = 0.04). Conclusions: These dose-volume-effect relationships provide initial IMRT optimization goals and motivate further efforts to reduce swallowing structures doses to reduce dysphagia and aspiration.« less

Recurrence in Region of Spared Parotid Gland After Definitive Intensity-Modulated Radiotherapy for Head and Neck Cancer

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

Cannon, Donald M.; Lee, Nancy Y.

2008-03-01

Purpose: To discuss the implications of three examples of periparotid recurrence after definitive intensity-modulated radiotherapy (IMRT) for head and neck cancer (HNC). Methods and Materials: We present 3 patients with HNC who underwent definitive IMRT with concurrent chemotherapy and later had treatment failure in or near a spared parotid gland. Two patients had bilateral multilevel nodal disease, and all had Level II nodal disease ipsilateral to the site of recurrence. The patients were treated using dose-painting IMRT with a dose of 70 Gy to the gross tumor volume and 59.4 Gy or 54 Gy to the high-risk or low-risk clinicalmore » tumor volume, respectively. The parotid glands were spared bilaterally. The patients had not undergone any surgical treatment for HNC before radiotherapy. Results: All patients had treatment failure in the region of a spared parotid gland. Failure in the 2 patients with bilateral multilevel nodal involvement occurred in the periparotid lymph nodes. The third patient developed a dermal metastasis near the tail of a spared parotid gland. On pretreatment imaging, the 2 patients with nodal failure had small nonspecific periparotid nodules that showed no hypermetabolic activity on positron emission tomography. Conclusion: For HNC patients receiving definitive IMRT, nonspecific positron emission tomography-negative periparotid nodules on pretreatment imaging should raise the index of suspicion for subclinical disease in the presence of multilevel or Level II nodal metastases. Additional evaluation of such nodules might be indicated before sparing the ipsilateral parotid gland.« less

SU-F-T-315: Comparative Studies of Planar Dose with Different Spatial Resolution for Head and Neck IMRT QA

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

Hwang, T; Koo, T

Purpose: To quantitatively investigate the planar dose difference and the γ value between the reference fluence map with the 1 mm detector-to-detector distance and the other fluence maps with less spatial resolution for head and neck intensity modulated radiation (IMRT) therapy. Methods: For ten head and neck cancer patients, the IMRT quality assurance (QA) beams were generated using by the commercial radiation treatment planning system, Pinnacle3 (ver. 8.0.d Philips Medical System, Madison, WI). For each beam, ten fluence maps (detector-to-detector distance: 1 mm to 10 mm by 1 mm) were generated. The fluence maps with larger than 1 mm detector-todetectormore » distance were interpolated using MATLAB (R2014a, the Math Works,Natick, MA) by four different interpolation Methods: for the bilinear, the cubic spline, the bicubic, and the nearest neighbor interpolation, respectively. These interpolated fluence maps were compared with the reference one using the γ value (criteria: 3%, 3 mm) and the relative dose difference. Results: As the detector-to-detector distance increases, the dose difference between the two maps increases. For the fluence map with the same resolution, the cubic spline interpolation and the bicubic interpolation are almost equally best interpolation methods while the nearest neighbor interpolation is the worst.For example, for 5 mm distance fluence maps, γ≤1 are 98.12±2.28%, 99.48±0.66%, 99.45±0.65% and 82.23±0.48% for the bilinear, the cubic spline, the bicubic, and the nearest neighbor interpolation, respectively. For 7 mm distance fluence maps, γ≤1 are 90.87±5.91%, 90.22±6.95%, 91.79±5.97% and 71.93±4.92 for the bilinear, the cubic spline, the bicubic, and the nearest neighbor interpolation, respectively. Conclusion: We recommend that the 2-dimensional detector array with high spatial resolution should be used as an IMRT QA tool and that the measured fluence maps should be interpolated using by the cubic spline interpolation or the bicubic interpolation for head and neck IMRT delivery. This work was supported by Radiation Technology R&D program through the National Research Foundation of Korea funded by the Ministry of Science, ICT & Future Planning (No. 2013M2A2A7038291)« less

Imaging Characteristics and Prevalence of Pancreatic Carcinoma in Kosovo During 2011-2015 - Diagnostic Method as Choice.

PubMed

Dedushi, Kreshnike; Kabashi, Serbeze; Mucaj, Sefedin; Hasbahta, Gazmed; Ramadani, Naser; Hoxhaj, Astrit

2016-06-01

Pancreatic cancer is the 10(th)most common malignancy and the 4(th)largest cancer killer in adults. The purpose of this paper is to evaluate the number of cases presented with pancreatic carcinoma during the years 2011-2015, our experience of the imaging characteristics of pancreatic carcinoma. We evaluated prevalence of the pancreatic cancers, distant metastases and other local infiltration signs among the total cases of the pancreatic cancers diagnosed in the University Clinical Center of Kosovo, with the aim to compare these research findings to similar studies made in the developed countries. This is a retrospective research study done during the period of 2011-2015. This retrospective research study includes 362 patients recently diagnosed with pancreatic cancer, examined in the period of 2011-2015 at the University Clinical Center of Kosovo. The imaging diagnostics are performed with MSCT Sensation 64 Siemens, MSCT Emotion 6 Siemens, and 1.5T MRI Symphony Siemens, biopsy guide with MSCT Sensation 64 Siemens in the Radiologic Clinic of UCCK; while the histopathology diagnostics has been performed in Clinic of Pathology at UCCK and prevalence is taken from the number of cases Reported at the Institute of Oncology Institute of Statistics and NIPH (National Institute of Public Health of Kosovo). Out of a total of the 362 patients diagnosed with pancreas cancer, results is female 39.5% (n=143) and male 61.5% (n=219), report M: F (1: 1.6), 286 cases resulted in head and neck 79 % (n=286), 76 cases resulted in body and tail cancers (21%), distant metastases in first imaging modality were found in(n=155) patients 43 %, local infiltration was found in patients: gastric infiltration 15 % (n=54), duodenal and papilla infiltration 26% (n=94), local infiltration spleen 16% (n=57), local infiltration mesentery 43 % (n= 155), dilated biliary tree 34 % (n=123), regional lymph node infiltration 83 % (n= 300). Out of a total of the 362 patients diagnosed with pancreas cancer, 346 cases resulted > 2 cm and 16 cases resulted < 2 cm and with component cystic was 41.2 % (n = 149), solid with component cystic - necrotic 33% (n= 119), solid 25.7% (n= 93). The prevalence is 19.9: 100,000 inhabitants. Prevalence of carcinoma of the pancreas for 5 years in Kosovo has proved to be prevalence is 19.9: 100,000 inhabitants. Seventy-four percent (74 %, n= 268) of all cancers are found in Stage III and IV. From an imaging point of view, these cancers were presented in an advanced stage, mainly due to their late clinical symptoms and limited access to imaging methods in our country.

Imaging Characteristics and Prevalence of Pancreatic Carcinoma in Kosovo During 2011-2015 - Diagnostic Method as Choice

PubMed Central

Dedushi, Kreshnike; Kabashi, Serbeze; Mucaj, Sefedin; Hasbahta, Gazmed; Ramadani, Naser; Hoxhaj, Astrit

2016-01-01

Introduction: Pancreatic cancer is the 10thmost common malignancy and the 4thlargest cancer killer in adults. Aim: The purpose of this paper is to evaluate the number of cases presented with pancreatic carcinoma during the years 2011-2015, our experience of the imaging characteristics of pancreatic carcinoma. We evaluated prevalence of the pancreatic cancers, distant metastases and other local infiltration signs among the total cases of the pancreatic cancers diagnosed in the University Clinical Center of Kosovo, with the aim to compare these research findings to similar studies made in the developed countries. This is a retrospective research study done during the period of 2011-2015. Materials and Methodology: This retrospective research study includes 362 patients recently diagnosed with pancreatic cancer, examined in the period of 2011-2015 at the University Clinical Center of Kosovo. The imaging diagnostics are performed with MSCT Sensation 64 Siemens, MSCT Emotion 6 Siemens, and 1.5T MRI Symphony Siemens, biopsy guide with MSCT Sensation 64 Siemens in the Radiologic Clinic of UCCK; while the histopathology diagnostics has been performed in Clinic of Pathology at UCCK and prevalence is taken from the number of cases Reported at the Institute of Oncology Institute of Statistics and NIPH (National Institute of Public Health of Kosovo). Results: Out of a total of the 362 patients diagnosed with pancreas cancer, results is female 39.5% (n=143) and male 61.5% (n=219), report M: F (1: 1.6), 286 cases resulted in head and neck 79 % (n=286), 76 cases resulted in body and tail cancers (21%), distant metastases in first imaging modality were found in(n=155) patients 43 %, local infiltration was found in patients: gastric infiltration 15 % (n=54), duodenal and papilla infiltration 26% (n=94), local infiltration spleen 16% (n=57), local infiltration mesentery 43 % (n= 155), dilated biliary tree 34 % (n=123), regional lymph node infiltration 83 % (n= 300). Out of a total of the 362 patients diagnosed with pancreas cancer, 346 cases resulted > 2 cm and 16 cases resulted < 2 cm and with component cystic was 41.2 % (n = 149), solid with component cystic – necrotic 33% (n= 119), solid 25.7% (n= 93). The prevalence is 19.9: 100,000 inhabitants. Conclusions: Prevalence of carcinoma of the pancreas for 5 years in Kosovo has proved to be prevalence is 19.9: 100,000 inhabitants. Seventy-four percent (74 %, n= 268) of all cancers are found in Stage III and IV. From an imaging point of view, these cancers were presented in an advanced stage, mainly due to their late clinical symptoms and limited access to imaging methods in our country. PMID:27482128

Five-Week Outcomes From a Dosing Trial of Therapeutic Massage for Chronic Neck Pain

PubMed Central

Sherman, Karen J.; Cook, Andrea J.; Wellman, Robert D.; Hawkes, Rene J.; Kahn, Janet R.; Deyo, Richard A.; Cherkin, Daniel C.

2014-01-01

PURPOSE This trial was designed to evaluate the optimal dose of massage for individuals with chronic neck pain. METHODS We recruited 228 individuals with chronic nonspecific neck pain from an integrated health care system and the general population, and randomized them to 5 groups receiving various doses of massage (a 4-week course consisting of 30-minute visits 2 or 3 times weekly or 60-minute visits 1, 2, or 3 times weekly) or to a single control group (a 4-week period on a wait list). We assessed neck-related dysfunction with the Neck Disability Index (range, 0–50 points) and pain intensity with a numerical rating scale (range, 0–10 points) at baseline and 5 weeks. We used log-linear regression to assess the likelihood of clinically meaningful improvement in neck-related dysfunction (≥5 points on Neck Disability Index) or pain intensity (≥30% improvement) by treatment group. RESULTS After adjustment for baseline age, outcome measures, and imbalanced covariates, 30-minute treatments were not significantly better than the wait list control condition in terms of achieving a clinically meaningful improvement in neck dysfunction or pain, regardless of the frequency of treatments. In contrast, 60-minute treatments 2 and 3 times weekly significantly increased the likelihood of such improvement compared with the control condition in terms of both neck dysfunction (relative risk = 3.41 and 4.98, P = .04 and .005, respectively) and pain intensity (relative risk = 2.30 and 2.73; P = .007 and .001, respectively). CONCLUSIONS After 4 weeks of treatment, we found multiple 60-minute massages per week more effective than fewer or shorter sessions for individuals with chronic neck pain. Clinicians recommending massage and researchers studying this therapy should ensure that patients receive a likely effective dose of treatment. PMID:24615306

Effect of CT contrast on volumetric arc therapy planning (RapidArc and helical tomotherapy) for head and neck cancer

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

Liu, Alan J.; Vora, Nayana; Suh, Steve

2015-04-01

The objectives of the study were to evaluate the effect of intravenous contrast in the dosimetry of helical tomotherapy and RapidArc treatment for head and neck cancer and determine if it is acceptable during the computed tomography (CT) simulation to acquire only CT with contrast for treatment planning of head and neck cancer. Overall, 5 patients with head and neck cancer (4 men and 1 woman) treated on helical tomotherapy were analyzed retrospectively. For each patient, 2 consecutive CT scans were performed. The first CT set was scanned before the contrast injection and secondary study set was scanned 45 secondsmore » after contrast. The 2 CTs were autoregistered using the same Digital Imaging and Communications in Medicine coordinates. Tomotherapy and RapidArc plans were generated on 1 CT data set and subsequently copied to the second CT set. Dose calculation was performed, and dose difference was analyzed to evaluate the influence of intravenous contrast media. The dose matrix used for comparison included mean, minimum and maximum doses of planning target volume (PTV), PTV dose coverage, and V{sub 45} {sub Gy}, V{sub 30} {sub Gy}, and V{sub 20} {sub Gy} organ doses. Treatment planning on contrasted images generally showed a lower dose to both organs and target than plans on noncontrasted images. The doses for the points of interest placed in the organs and target rarely changed more than 2% in any patient. In conclusion, treatment planning using a contrasted image had insignificant effect on the dose to the organs and targets. In our opinion, only CT with contrast needs to be acquired during the CT simulation for head and neck cancer. Dose calculations performed on contrasted images can potentially underestimate the delivery dose slightly. However, the errors of planning on a contrasted image should not affect the result in clinically significant way.« less

Xerostomia and its predictors following parotid-sparing irradiation of head-and-neck cancer.

PubMed

Eisbruch, A; Kim, H M; Terrell, J E; Marsh, L H; Dawson, L A; Ship, J A

2001-07-01

To assess long-term xerostomia in patients receiving parotid-sparing radiation therapy (RT) for head-and-neck cancer, and to find the patient and therapy-related factors that affect its severity. From March 1994 through January 2000, 84 patients received comprehensive bilateral neck RT using conformal and multisegmental intensity-modulated RT (IMRT) aiming to spare the major salivary glands. Before RT and periodically through 2 years after the completion of RT, salivary flow rates from each of the major salivary glands were selectively measured. At the same time intervals, each patient completed an 8-item self-reported xerostomia-specific questionnaire (XQ). To gain a relative measure of the effect of RT on the minor salivary glands, whose output could not be measured, the surfaces of the oral cavity (extending to include the surface of the base of tongue) were outlined in the planning CT scans. The mean doses to the new organ ("oral cavity") were recorded. Forty-eight patients receiving unilateral neck RT were similarly studied and served as a benchmark for comparison. Factors predicting the XQ scores were analyzed using a random-effects model. The XQ was found to be reliable and valid in measuring patient-reported xerostomia. The spared salivary glands which had received moderate doses in the bilateral RT group recovered to their baseline salivary flow rates during the second year after RT, and the spared glands in the unilateral RT group, which had received very low doses, demonstrated increased salivary production beyond their pre-RT levels. The increase in the salivary flow rates during the second year after RT paralleled an improvement in xerostomia in both patient groups. The improvement in xerostomia was faster in the unilateral compared with the bilateral RT group, but the difference narrowed at 2 years. The major salivary gland flow rates had only a weak correlation with the xerostomia scores. Factors found to be independently associated with the xerostomia scores were the pre-RT baseline scores, the time since RT, and the mean doses to the major salivary glands (notably to the submandibular glands) and to the oral cavity. An improvement over time in xerostomia, occurring in tandem with rising salivary production from the spared major salivary glands, suggests a long-term clinical benefit from their sparing. The oral cavity mean dose, representing RT effect on the minor salivary glands, was found to be a significant, independent predictor of xerostomia. Thus, in addition to the major salivary glands, sparing the uninvolved oral cavity should be considered as a planning objective to further reduce xerostomia.

[Comparison of planning quality and delivery efficiency between volumetric modulated arc therapy and dynamic intensity modulated radiation therapy for nasopharyngeal carcinoma with more than 4 prescribed dose levels].

PubMed

Jia, Pengfei; Xu, Jun; Zhou, Xiaoxi; Chen, Jian; Tang, Lemin

2017-12-01

The aim of this study is to compare the planning quality and delivery efficiency between dynamic intensity modulated radiation therapy (d-IMRT) and dual arc volumetric modulated arc therapy (VMAT) systematically for nasopharyngeal carcinoma (NPC) patients with multi-prescribed dose levels, and to analyze the correlations between target volumes and plan qualities. A total of 20 patients of NPC with 4-5 prescribed dose levels to achieve simultaneous integrated boost (SIB) treated by sliding window d-IMRT in our department from 2014 to 2015 were re-planned with dual arc VMAT. All optimization objectives for each VMAT plan were as the same as the corresponding d-IMRT plan. The dose parameters for targets and organ at risk (OAR), the delivery time and monitor units (MU) in two sets of plans were compared respectively. The treatment accuracy was tested by three dimensional dose validation system. Finally, the correlations between the difference of planning quality and the volume of targets were discussed. The conform indexes (CIs) of planning target volumes (PTVs) in VMAT plans were obviously high than those in d-IMRT plans ( P < 0.05), but no significant correlations between the difference of CIs and the volume of targets were discovered ( P > 0.05). The target coverage and heterogeneity indexes (HIs) of PTV 1 and PGTV nd and PTV 3 in two sets of plans were consistent. The doses of PTV 2 decreased and HIs were worse in VMAT plans. VMAT could provide better spinal cord and brainstem sparing, but increase mean dose of parotids. The average number of MUs and delivery time for d-IMRT were 3.32 and 2.19 times of that for VMAT. The γ-index (3 mm, 3%) analysis for each plans was more than 97% in COMPASS ® measurement for quality assurance (QA). The results show that target dose coverages in d-IMRT and VMAT plans are similar for NPC with multi-prescribed dose levels. VMAT could improve the the CIs of targets, but reduce the dose to the target volume in neck except for PGTV nd . The biggest advantages of VMAT over d-IMRT are delivery efficiency and QA.

Impact of electrocardiogram-gated multi-slice computed tomography-based aortic annular measurement in the evaluation of paravalvular leakage following transcatheter aortic valve replacement: the efficacy of the OverSized AortiC Annular ratio (OSACA ratio) in TAVR.

PubMed

Maeda, Koichi; Kuratani, Toru; Torikai, Kei; Shimamura, Kazuo; Mizote, Isamu; Ichibori, Yasuhiro; Takeda, Yasuharu; Daimon, Takashi; Nakatani, Satoshi; Nanto, Shinsuke; Sawa, Yoshiki

2013-07-01

Even mild paravalvular leakage (PVL) after transcatheter aortic valve replacement (TAVR) is associated with increased late mortality. Electrocardiogram-gated multi-slice computed tomography (MSCT) enables detailed aortic annulus assessment. We describe the impact of MSCT for PVL following TAVR. Congruence between the prosthesis and annulus diameters affects PVL; therefore, we calculated the OverSized AortiC Annular ratio (OSACA ratio) and OSACA (transesophageal echocardiography, TEE) ratio as prosthesis diameter/annulus diameter on MSCT or TEE, respectively, and compared their relationship with PVL ≤ trace following TAVR. Of 36 consecutive patients undergoing TAVR (Group A), the occurrence of PVL ≤ trace (33.3%) was significantly related to the OSACA ratio (p = 0.00020). In receiver-operating characteristics analysis, the cutoff value of 1.03 for the OSACA ratio had the highest sum of sensitivity (75.0%) and specificity (91.7%; AUC = 0.87) with significantly higher discriminatory performance for PVL as compared to the OSACA (TEE) ratio (AUC = 0.69, p = 0.028). In nine consecutive patients (Group B) undergoing TAVR based on guidelines formulated from our experience with Group A, PVL ≤ trace was significantly more frequent (88.9%) than that in Group A (p = 0.0060). The OSACA ratio has a significantly higher discriminatory performance for PVL ≤ trace than the OSACA (TEE) ratio, and aortic annular measurement from MSCT is more accurate than that from TEE. © 2013 Wiley Periodicals, Inc.

Development of modern human subadult age and sex estimation standards using multi-slice computed tomography images from medical examiner's offices

NASA Astrophysics Data System (ADS)

Stock, Michala K.; Stull, Kyra E.; Garvin, Heather M.; Klales, Alexandra R.

2016-10-01

Forensic anthropologists are routinely asked to estimate a biological profile (i.e., age, sex, ancestry and stature) from a set of unidentified remains. In contrast to the abundance of collections and techniques associated with adult skeletons, there is a paucity of modern, documented subadult skeletal material, which limits the creation and validation of appropriate forensic standards. Many are forced to use antiquated methods derived from small sample sizes, which given documented secular changes in the growth and development of children, are not appropriate for application in the medico-legal setting. Therefore, the aim of this project is to use multi-slice computed tomography (MSCT) data from a large, diverse sample of modern subadults to develop new methods to estimate subadult age and sex for practical forensic applications. The research sample will consist of over 1,500 full-body MSCT scans of modern subadult individuals (aged birth to 20 years) obtained from two U.S. medical examiner's offices. Statistical analysis of epiphyseal union scores, long bone osteometrics, and os coxae landmark data will be used to develop modern subadult age and sex estimation standards. This project will result in a database of information gathered from the MSCT scans, as well as the creation of modern, statistically rigorous standards for skeletal age and sex estimation in subadults. Furthermore, the research and methods developed in this project will be applicable to dry bone specimens, MSCT scans, and radiographic images, thus providing both tools and continued access to data for forensic practitioners in a variety of settings.

[Significance and mechanism of MSCT perfusion scan on differentiation of NSCLC].

PubMed

Liu, Jin-Kang; Hu, Cheng-Ping; Zhou, Mo-Ling; Zhou, Hui; Xiong, Zeng; Xia, Yu; Chen, Wei

2009-06-01

To determine the significance of MSCT perfusion scan on differentiation of NSCLC and to investigate its possible mechanisms. Forty four NSCLC patients underwent CT perfusion scan by MSCT. Among them, 22 cases were selected to detected the two-dimensional tumor microvascular architecture phenotype (2D-TMAP), the relationships between CT perfusion parameters (BF, BV, PEI, TIP), and the differentiation of NSCLC were analysed by using the correlation analysis and trend test. Spearman correlation analysis was used to study the relationships between CT perfusion parameters, differentiation, and 2D-TMAP. The total BF, BV and PEI decreased with decreasing differentiation of NSCLC (P<0.05). The total PEI showed a positive correlation with the total MVD (P<0.05). There were negative correlations between the surrounding area BF, the total BF, BV, and PEI, the uncomplete lumen of the surrounding area MVD, and expression of PCNA, respectively (P<0.05). There were positive correlations between degree of differentiation and the uncomplete lumen of the surrounding area MVD (P<0.05). It was the same as degree of differentiation and expression of PCNA, VEGF, respectively. There were positive correlations between the uncomplete lumen of the surrounding area MVD and expression of VEGF, ephrinB2, EphB4, and PCNA, respectively (P<0.05). Perfusion parameters reflect the difference of density of vassels with mature functional lumen. Careful evaluation of the differences of blood flow pattern in pulmonary space-occupying lesions by MSCT perfusion scan can be used to identify the degree of NSCLC differentiation.

Proof of live birth using postmortem multislice computed tomography (pmMSCT) in cases of suspected neonaticide: advantages of diagnostic imaging compared to conventional autopsy.

PubMed

Guddat, Saskia S; Gapert, René; Tsokos, Michael; Oesterhelweg, Lars

2013-03-01

Proof of live birth is of major importance in suspected neonaticide cases. Although not without controversy the lung flotation test is the main method used to asses this in different jurisdictions worldwide. The present study examines the usefulness of postmortem multislice computed tomography (pmMSCT) in the detection of live birth signs. Body scans were conducted on four infants, one was stillborn, another died a day after birth and the other two were classified as neonaticides. The appearance of the lungs, gastrointestinal tract and vascular system of the liver was compared in these cases. Clear differences were discernable between the lungs of the stillborn and the 1 day old infant. The aerated lungs and air in the stomach and duodenum were clearly visible in the latter case while the stillborn infant lacked these signs. The two neonaticide cases demonstrated similarly aerated lung tissue to the 1 day old infant. The hepatic vessels did not show any putrefactive gas changes in any of the cases. The extent of aeration of the peripheral alveoli was easily observable on the pmMSCT, thus making it a useful tool in the possible differentiation between artificially and naturally aerated lungs. During the four autopsies the classic flotation tests were performed and similar positive aeration of the lungs in the two neonaticides was shown. The stillborn's tests, on the other hand were negative for aeration. The results of this study clearly demonstrate the advantages of using pmMSCT before commencing a conventional autopsy in cases of suspected neonaticide.

Lhermitte Sign After Chemo-IMRT of Head-and-Neck Cancer: Incidence, Doses, and Potential Mechanisms

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

Pak, Daniel; Vineberg, Karen; Feng, Felix

2012-08-01

Purpose: We have observed a higher rate of Lhermitte sign (LS) after chemo-intensity-modulated radiotherapy (IMRT) of head-and-neck cancer than the published rates after conventional radiotherapy. We hypothesized that the inhomogeneous spinal cord dose distributions produced by IMRT caused a 'bath-and-shower' effect, characterized by low doses in the vicinity of high doses, reducing spinal cord tolerance. Methods and Materials: Seventy-three patients with squamous cell carcinoma of the oropharynx participated in a prospective study of IMRT concurrent with weekly carboplatin and paclitaxel. Of these, 15 (21%) reported LS during at least 2 consecutive follow-up visits. Mean dose, maximum dose, and partial volumemore » and absolute volume (in milliliters) of spinal cord receiving specified doses ({>=}10 Gy, {>=}20 Gy, {>=}30 Gy, and {>=}40 Gy), as well as the pattern of dose distributions at the 'anatomic' spinal cord (from the base of the skull to the aortic arch) and 'plan-related' spinal cord (from the top through the bottom of the planning target volumes), were compared between LS patients and 34 non-LS patients. Results: LS patients had significantly higher spinal cord mean doses, V{sub 30}, V{sub 40}, and absolute volumes receiving 30 Gy or more and 40 Gy or more compared with the non-LS patients (p < 0.05). The strongest predictors of LS were higher V{sub 40} and higher cord volumes receiving 40 Gy or more (p {<=} 0.007). There was no evidence of larger spinal cord volumes receiving low doses in the vicinity of higher doses (bath-and-shower effect) in LS compared with non-LS patients. Conclusions: Greater mean dose, V{sub 30}, V{sub 40}, and cord volumes receiving 30 Gy or more and 40 Gy or more characterized LS compared with non-LS patients. Bath-and-shower effects could not be validated in this study as a potential contributor to LS. The higher-than-expected rates of LS may be because of the specific concurrent chemotherapy agents or more accurate identification of LS in the setting of a prospective study.« less

Evaluation of the dose received in the tissues of the neck during quantification of iodine in the thyroid by X-ray fluorescence spectrometry

NASA Astrophysics Data System (ADS)

Portararo, Antonio; Licour, Caroline; Gerardy, Isabelle; Pozuelo Navarro, Fausto

2018-04-01

The determination of the iodine content in the thyroid is of great interest for many investigations of this gland. The conventional scintigraphic method, using radionuclides, is efficient but delivers a significant dose to the patient. The X-ray fluorescence spectrometry could give information about the iodine content in the thyroid. The measured signal is obtained after stimulation of the stable iodine contained in the gland by X-rays. The advantage of this technique is the complete absence of radioactive isotope injected into the patient body. By applying this, a decrease in effective dose to the patient should be obtained. In this work, the study of the dose received by a thyroid phantom (surrounded by the different tissues of the neck) was performed. The phantom is made of PLA. The dose is measured in optimised conditions defined for the analytical technique. A total head-neck phantom was also used in order to consider the absorbed dose in each different tissues and organs as spinal cord or eyes. Thermo-luminescence dosimeters were chosen for their small size, their sensitivity and the easy positioning on the surface of the phantom but also inside of it to evaluate dose to internal organs. Those LiF 100 dosimeters have been calibrated within the X-ray beam also used for the analysis of iodine. The repeatability and reproducibility of the method has been evaluated. The influence of parameters as concentration of iodine in the thyroid, distance between the X-ray generator and the neck, thickness of the tissues surrounding the thyroid, has been investigated in terms of modifying parameters of the dose received by different tissues situated in the neck and the head.

Can IMRT or Brachytherapy Reduce Dysphagia Associated With Chemoradiotherapy of Head and Neck Cancer? The Michigan and Rotterdam Experiences

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

Eisbruch, Avraham; Levendag, Peter C.; Feng, Felix Y.

Purpose: Dysphagia is a major late complication of intensive chemoradiotherapy of head and neck cancer. The initial clinical results of intensity-modulated radiotherapy (IMRT), or brachytherapy, planned specifically to reduce dysphagia are presented. Patients and Methods: Previous research at Michigan University has suggested that the pharyngeal constrictors and glottic and supraglottic larynx are likely structures whose damage by chemo-RT causes dysphagia and aspiration. In a prospective Michigan trial, 36 patients with oropharyngeal (n = 31) or nasopharyngeal (n = 5) cancer underwent chemo-IMRT. IMRT cost functions included sparing noninvolved pharyngeal constrictors and the glottic and supraglottic larynx. After a review ofmore » published studies, the retropharyngeal nodes at risk were defined as the lateral, but not the medial, retropharyngeal nodes, which facilitated sparing of the swallowing structures. In Rotterdam, 77 patients with oropharyngeal cancer were treated with IMRT, three dimensional RT, or conventional RT; also one-half received brachytherapy. The dysphagia endpoints included videofluoroscopy and observer-assessed scores at Michigan and patient-reported quality-of-life instruments in both studies. Results: In both studies, the doses to the upper and middle constrictors correlated highly with the dysphagia endpoints. In addition, doses to the glottic and supraglottic larynx were significant in the Michigan series. In the Rotterdam series, brachytherapy (which reduced the doses to the swallowing structures) was the only significant factor on multivariate analysis. Conclusion: The dose-response relationships for the swallowing structures found in these studies suggest that reducing their doses, using either IMRT aimed at their sparing, or brachytherapy, might achieve clinical gains in dysphagia.« less

Internal and external generalizability of temporal dose-response relationships for xerostomia following IMRT for head and neck cancer

PubMed Central

Thor, Maria; Owosho, Adepitan A; Clark, Haley D; Oh, Jung Hun; Riaz, Nadeem; Hovan, Allan; Tsai, Jillian; Thomas, Steven D; Yom, Sae Hee K; Wu, Jonn S; Huryn, Joseph M; Moiseenko, Vitali; Lee, Nancy Y; Estilo, Cherry L; Deasy, Joseph O

2016-01-01

Background and Purpose To study internal and external generalizability of temporal dose-response relationships for xerostomia after intensity-modulated radiotherapy (IMRT) for head and neck cancer, and to investigate potential amendments of the QUANTEC guidelines. Material and Methods Objective xerostomia was assessed in 121 patients (nCohort1=55; nCohort2=66) treated to 70Gy@2Gy in 2006–2015. Univariate and multivariate analyses (UVA, MVA with 1000 bootstrap populations) were conducted in Cohort1, and generalizability of the best-performing MVA model was investigated in Cohort2 (performance: AUC, p-values, and Hosmer-Lemeshow p-values (pHL)). Ultimately and for clinical guidance, minimum mean dose thresholds to the contralateral and the ipsilateral parotid glands (Dmeancontra, Dmeanipsi) were estimated from the generated dose-response curves. Results The observed xerostomia rate was 38%/47% (3 months) and 19%/23% (11–12 months) in Cohort1/Cohort2. Risk of xerostomia at 3 months increased for higher Dmeancontra and Dmeanipsi (Cohort1: 0.17•Dmeancontra+0.11•Dmeanipsi−8.13; AUC=0.90±0.05; p=0.0002±0.002; pHL=0.22±0.23; Cohort2: AUC=0.81; p<0.0001; pHL=0.27). The identified minimum Dmeancontra thresholds were lower than in the QUANTEC guidelines (Cohort1/Cohort2: Dmeancontra=12/19 Gy; Dmeancontra, Dmeanipsi=16, 25/20, 26 Gy). Conclusions Increased Dmeancontra and Dmeanipsi explain short-term xerostomia following IMRT. Our results also suggest decreasing Dmeancontra to below 20 Gy, while keeping Dmeanipsi to around 25 Gy. Long-term xerostomia was less frequent, and no dose-response relationship was established for this follow-up time. PMID:27890427

Internal and external generalizability of temporal dose-response relationships for xerostomia following IMRT for head and neck cancer.

PubMed

Thor, Maria; Owosho, Adepitan A; Clark, Haley D; Oh, Jung Hun; Riaz, Nadeem; Hovan, Allan; Tsai, Jillian; Thomas, Steven D; Yom, Sae Hee K; Wu, Jonn S; Huryn, Joseph M; Moiseenko, Vitali; Lee, Nancy Y; Estilo, Cherry L; Deasy, Joseph O

2017-02-01

To study internal and external generalizability of temporal dose-response relationships for xerostomia after intensity-modulated radiotherapy (IMRT) for head and neck cancer, and to investigate potential amendments of the QUANTEC guidelines. Objective xerostomia was assessed in 121 patients (n Cohort1 =55; n Cohort2 =66) treated to 70Gy@2Gy in 2006-2015. Univariate and multivariate analyses (UVA, MVA with 1000 bootstrap populations) were conducted in Cohort1, and generalizability of the best-performing MVA model was investigated in Cohort2 (performance: AUC, p-values, and Hosmer-Lemeshow p-values (p HL )). Ultimately and for clinical guidance, minimum mean dose thresholds to the contralateral and the ipsilateral parotid glands (Dmean contra , Dmean ipsi ) were estimated from the generated dose-response curves. The observed xerostomia rate was 38%/47% (3months) and 19%/23% (11-12months) in Cohort1/Cohort2. Risk of xerostomia at 3months increased for higher Dmean contra and Dmean ipsi (Cohort1: 0.17·Dmean contra +0.11·Dmean ipsi -8.13; AUC=0.90±0.05; p=0.0002±0.002; p HL =0.22±0.23; Cohort2: AUC=0.81; p<0.0001; p HL =0.27). The identified minimum Dmean contra thresholds were lower than in the QUANTEC guidelines (Cohort1/Cohort2: Dmean contra =12/19Gy; Dmean contra , Dmean ipsi =16, 25/20, 26Gy). Increased Dmean contra and Dmean ipsi explain short-term xerostomia following IMRT. Our results also suggest decreasing Dmean contra to below 20Gy, while keeping Dmean ipsi to around 25Gy. Long-term xerostomia was less frequent, and no dose-response relationship was established for this follow-up time. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

The incidence of coronary anomalies on routine coronary computed tomography scans

PubMed Central

Karabay, Kanber Ocal; Yildiz, Abdulmelik; Bagirtan, Bayram; Geceer, Gurkan; Uysal, Ender

2013-01-01

Summary Objective This study aimed to assess the incidence of coronary anomalies using 64-multi-slice coronary computed tomography (MSCT). Methods The diagnostic MSCT scans of 745 consecutive patients were reviewed. Results The incidence of coronary anomalies was 4.96%. The detected coronary anomalies included the conus artery originating separately from the right coronary sinus (RCS) (n = 8, 1.07%), absence of the left main artery (n = 7, 0.93%), a superior right coronary artery (RCA) (n = 7, 0.93%), the circumflex artery (CFX) arising from the RCS (n = 4, 0.53%), the CFX originating from the RCA (n = 2, 0.26%), a posterior RCA (n = 1, 0.13%), a coronary fistula from the left anterior descending artery and RCA to the pulmonary artery (n = 1, 0.13%), and a coronary aneurysm (n = 1, 0.13%). Conclusions This study indicated that MSCT can be used to detect common coronary anomalies, and shows it has the potential to aid cardiologists and cardiac surgeons by revealing the origin and course of the coronary vessels. PMID:24042853

Comparison of treatment plans: a retrospective study by the method of radiobiological evaluation

NASA Astrophysics Data System (ADS)

Puzhakkal, Niyas; Kallikuzhiyil Kochunny, Abdullah; Manthala Padannayil, Noufal; Singh, Navin; Elavan Chalil, Jumanath; Kulangarakath Umer, Jamshad

2016-09-01

There are many situations in radiotherapy where multiple treatment plans need to be compared for selection of an optimal plan. In this study we performed the radiobiological method of plan evaluation to verify the treatment plan comparison procedure of our clinical practice. We estimated and correlated various radiobiological dose indices with physical dose metrics for a total of 30 patients representing typical cases of head and neck, prostate and brain tumors. Three sets of plans along with a clinically approved plan (final plan) treated by either Intensity Modulated Radiation Therapy (IMRT) or Rapid Arc (RA) techniques were considered. The study yielded improved target coverage for final plans, however, no appreciable differences in doses and the complication probabilities of organs at risk were noticed. Even though all four plans showed adequate dose distributions, from dosimetric point of view, the final plan had more acceptable dose distribution. The estimated biological outcome and dose volume histogram data showed least differences between plans for IMRT when compared to RA. Our retrospective study based on 120 plans, validated the radiobiological method of plan evaluation. The tumor cure or normal tissue complication probabilities were found to be correlated with the corresponding physical dose indices.

Radiation dose reduction using a neck detection algorithm for single spiral brain and cervical spine CT acquisition in the trauma setting.

PubMed

Ardley, Nicholas D; Lau, Ken K; Buchan, Kevin

2013-12-01

Cervical spine injuries occur in 4-8 % of adults with head trauma. Dual acquisition technique has been traditionally used for the CT scanning of brain and cervical spine. The purpose of this study was to determine the efficacy of radiation dose reduction by using a single acquisition technique that incorporated both anatomical regions with a dedicated neck detection algorithm. Thirty trauma patients for brain and cervical spine CT were included and were scanned with the single acquisition technique. The radiation doses from the single CT acquisition technique with the neck detection algorithm, which allowed appropriate independent dose administration relevant to brain and cervical spine regions, were recorded. Comparison was made both to the doses calculated from the simulation of the traditional dual acquisitions with matching parameters, and to the doses of retrospective dual acquisition legacy technique with the same sample size. The mean simulated dose for the traditional dual acquisition technique was 3.99 mSv, comparable to the average dose of 4.2 mSv from 30 previous patients who had CT of brain and cervical spine as dual acquisitions. The mean dose from the single acquisition technique was 3.35 mSv, resulting in a 16 % overall dose reduction. The images from the single acquisition technique were of excellent diagnostic quality. The new single acquisition CT technique incorporating the neck detection algorithm for brain and cervical spine significantly reduces the overall radiation dose by eliminating the unavoidable overlapping range between 2 anatomical regions which occurs with the traditional dual acquisition technique.

Repeated Neck Restraint Stress Bidirectionally Modulates Excitatory Transmission in the Dentate Gyrus and Performance in a Hippocampus-dependent Memory Task.

PubMed

Spyrka, Jadwiga; Hess, Grzegorz

2018-05-21

The consequences of stress depend on characteristics of the stressor, including the duration of exposure, severity, and predictability. Exposure of mice to repeated neck restraint has been shown to bidirectionally modulate the potential for long-term potentiation (LTP) in the dentate gyrus (DG) in a manner dependent on the number of restraint repetitions, but the influence of repeated brief neck restraint on electrophysiology of single DG neurons has not yet been investigated. Here, we aimed at finding the effects of 1, 3, 7, 14, or 21 daily neck restraint sessions lasting 10 min on electrophysiological characteristics of DG granule cells as well as excitatory and inhibitory synaptic inputs to these neurons. While the excitability of DG granule cells and inhibitory synaptic transmission were unchanged, neck restraint decreased the frequency of spontaneous excitatory currents after three repetitions but enhanced it after 14 and 21 repetitions. The consequences of repeated neck restraint on hippocampus-dependent memory were investigated using the object location test (OLT). Neck restraint stress impaired cognitive performance in the OLT after three repetitions but improved it after 14 and 21 repetitions. Mice subjected to three neck restraint sessions displayed an increase in the measures of depressive and anxiety-like behaviors, however, prolongation of the exposure to neck restraint resulted in a gradual decline in the intensity of these measures. These data indicate that stress imposed by an increasing number of repeated neck restraint episodes bidirectionally modulates both excitatory synaptic transmission in the DG and cognitive performance in the object location memory task. Copyright © 2018 IBRO. Published by Elsevier Ltd. All rights reserved.

Physical and biological pretreatment quality assurance of the head and neck cancer plan with the volumetric modulated arc therapy

NASA Astrophysics Data System (ADS)

Park, So-Hyun; Lee, Dong-Soo; Lee, Yun-Hee; Lee, Seu-Ran; Kim, Min-Ju; Suh, Tae-Suk

2015-09-01

The aim of this work is to demonstrate both the physical and the biological quality assurance (QA) aspects as pretreatment QA of the head and neck (H&N) cancer plan for the volumetric modulated arc therapy (VMAT). Ten H&N plans were studied. The COMPASS® dosimetry analysis system and the tumor control probability (TCP) and the normal tissue complication probability (NTCP) calculation free program were used as the respective measurement and calculation tools. The reliability of these tools was verified by a benchmark study in accordance with the TG-166 report. For the physical component of QA, the gamma passing rates and the false negative cases between the calculated and the measured data were evaluated. The biological component of QA was performed based on the equivalent uniform dose (EUD), TCP and NTCP values. The evaluation was performed for the planning target volumes (PTVs) and the organs at risks (OARs), including the eyes, the lens, the parotid glands, the esophagus, the spinal cord, and the brainstem. All cases had gamma passing rates above 95% at an acceptance tolerance level with the 3%/3 mm criteria. In addition, the false negative instances were presented for the PTVs and OARs. The gamma passing rates exhibited a weak correlation with false negative cases. For the biological QA, the physical dose errors affect the EUD and the TCP for the PTVs, but no linear correlation existed between them. The EUD and NTCP for the OARs were shown the random differences that could not be attributed to the dose errors from the physical QA. The differences in the EUD and NTCP between the calculated and the measured results were mainly demonstrated for the parotid glands. This study describes the importance and the necessity of improved QA to accompany both the physical and the biological aspects for accurate radiation treatment.

Tadalafil Reduces Myeloid-Derived Suppressor Cells and Regulatory T Cells and Promotes Tumor Immunity in Patients with Head and Neck Squamous Cell Carcinoma

PubMed Central

Vella, Jennifer L.; Reis, Isildinha M.; De la fuente, Adriana C.; Gomez, Carmen; Sargi, Zoukaa; Nazarian, Ronen; Califano, Joseph; Borrello, Ivan

2015-01-01

Purpose Myeloid-derived suppressor cells (MDSC) and regulatory T cells (Treg) play a key role in the progression of head and neck squamous cell carcinoma (HNSCC). On the basis of our preclinical data demonstrating that phosphodiesterase-5 (PDE5) inhibition can modulate these cell populations, we evaluated whether the PDE5 inhibitor tadalafil can revert tumor-induced immunosuppression and promote tumor immunity in patients with HNSCC. Experimental Design First, we functionally and phenotypically characterized MDSCs in HNSCCs and determined, retrospectively, whether their presence at the tumor site correlates with recurrence. Then, we performed a prospective single-center, double-blinded, randomized, three-arm study in which patients with HNSCC undergoing definitive surgical resection of oral and oropharyngeal tumors were treated with tadalafil 10 μg/day, 20 μg/day, or placebo for at least 20 days preoperatively. Blood and tumor MDSC and Treg presence and CD8+ T-cell reactivity to tumor antigens were evaluated before and after treatment. Results MDSCs were characterized in HNSCC and their intratumoral presence significantly correlates with recurrence. Tadalafil treatment was well tolerated and significantly reduced both MDSCs and Treg concentrations in the blood and in the tumor (P < 0.05). In addition, the concentration of blood CD8+ T cells reactive to autologous tumor antigens significantly increased after treatment (P < 0.05). Tadalafil immunomodulatory activity was maximized at an intermediate dose but not at higher doses. Mechanistic analysis suggests a possible off-target effect on PDE11 at high dosages that, by increasing intracellular cAMP, may negatively affect antitumor immunity. Conclusions Tadalafil seems to beneficially modulate the tumor micro- and macro-environment in patients with HNSCC by lowering MDSCs and Tregs and increasing tumor-specific CD8+ T cells in a dose-dependent fashion. PMID:25320361

Fluorine-18-Labeled Fluoromisonidazole Positron Emission and Computed Tomography-Guided Intensity-Modulated Radiotherapy for Head and Neck Cancer: A Feasibility Study

PubMed Central

Lee, Nancy Y.; Mechalakos, James G.; Nehmeh, Sadek; Lin, Zhixiong; Squire, Olivia D.; Cai, Shangde; Chan, Kelvin; Zanzonico, Pasquale B.; Greco, Carlo; Ling, Clifton C.; Humm, John L.; Schöder, Heiko

2010-01-01

Purpose Hypoxia renders tumor cells radioresistant, limiting locoregional control from radiotherapy (RT). Intensity-modulated RT (IMRT) allows for targeting of the gross tumor volume (GTV) and can potentially deliver a greater dose to hypoxic subvolumes (GTVh) while sparing normal tissues. A Monte Carlo model has shown that boosting the GTVh increases the tumor control probability. This study examined the feasibility of fluorine-18–labeled fluoromisonidazole positron emission tomography/computed tomography (18F-FMISO PET/CT)–guided IMRT with the goal of maximally escalating the dose to radioresistant hypoxic zones in a cohort of head and neck cancer (HNC) patients. Methods and Materials 18F-FMISO was administered intravenously for PET imaging. The CT simulation, fluorodeoxyglucose PET/CT, and 18F-FMISO PET/CT scans were co-registered using the same immobilization methods. The tumor boundaries were defined by clinical examination and available imaging studies, including fluorodeoxyglucose PET/CT. Regions of elevated 18F-FMISO uptake within the fluorodeoxyglucose PET/CT GTV were targeted for an IMRT boost. Additional targets and/or normal structures were contoured or transferred to treatment planning to generate 18F-FMISO PET/CT-guided IMRT plans. Results The heterogeneous distribution of 18F-FMISO within the GTV demonstrated variable levels of hypoxia within the tumor. Plans directed at performing 18F-FMISO PET/CT–guided IMRT for 10 HNC patients achieved 84 Gy to the GTVh and 70 Gy to the GTV, without exceeding the normal tissue tolerance. We also attempted to deliver 105 Gy to the GTVh for 2 patients and were successful in 1, with normal tissue sparing. Conclusion It was feasible to dose escalate the GTVh to 84 Gy in all 10 patients and in 1 patient to 105 Gy without exceeding the normal tissue tolerance. This information has provided important data for subsequent hypoxia-guided IMRT trials with the goal of further improving locoregional control in HNC patients. PMID:17869020

A Dosimetric Comparison of Proton and Intensity Modulated Radiation Therapy in Pediatric Rhabdomyosarcoma Patients Enrolled on a Prospective Phase II Proton Study

PubMed Central

Ladra, Matthew M.; Edgington, Samantha K.; Mahajan, Anita; Grosshans, David; Szymonifka, Jackie; Khan, Fazal; Moteabbed, Maryam; Friedmann, Alison M.; MacDonald, Shannon M.; Tarbell, Nancy J.; Yock, Torunn I.

2015-01-01

Background Pediatric rhabdomyosarcoma (RMS) is highly curable, however, cure may come with significant radiation related toxicity in developing tissues. Proton therapy (PT) can spare excess dose to normal structures, potentially reducing the incidence of adverse effects. Methods Between 2005 and 2012, 54 patients were enrolled on a prospective multi-institutional phase II trial using PT in pediatric RMS. As part of the protocol, intensity modulated radiation therapy (IMRT) plans were generated for comparison with clinical PT plans. Results Target coverage was comparable between PT and IMRT plans with a mean CTV V95 of 100% for both modalities (p=0.82). However, mean integral dose was 1.8 times higher for IMRT (range 1.0-4.9). By site, mean integral dose for IMRT was 1.8 times higher for H&N (p<0.01) and GU (p=0.02), 2.0 times higher for trunk/extremity (p<0.01), and 3.5 times higher for orbit (p<0.01) compared to PT. Significant sparing was seen with PT in 26 of 30 critical structures assessed for orbital, head and neck, pelvic, and trunk/extremity patients. Conclusions Proton radiation lowers integral dose and improves normal tissue sparing when compared to IMRT for pediatric RMS. Correlation with clinical outcomes is necessary once mature long-term toxicity data are available. PMID:25443861

Angular on-line tube current modulation in multidetector CT examinations of children and adults: The influence of different scanning parameters on dose reduction

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

Papadakis, Antonios E.; Perisinakis, Kostas; Damilakis, John

2007-07-15

The purpose of this study was to assess the potential of angular on-line tube current modulation on dose reduction in pediatric and adult patients undergoing multidetector computed tomography (MDCT) examinations. Five physical anthropomorphic phantoms that simulate the average individual as neonate, 1-year-old, 5-year-old, 10-year-old, and adult were employed in the current study. Phantoms were scanned with the use of on-line tube current modulation (TCM). Percent dose reduction (%DR) factors achieved by applying TCM, were determined for standard protocols used for head and neck, shoulder, thorax, thorax and abdomen, abdomen, abdomen and pelvis, pelvis, and whole body examinations. A preliminary studymore » on the application of TCM in MDCT examinations of adult patients was performed to validate the results obtained in anthropomorphic phantoms. Dose reduction was estimated as the percentage difference of the modulated milliamperes for each scan and the preset milliamperes prescribed by the scan protocol. The dose reduction in children was found to be much lower than the corresponding reduction achieved for adults. For helical scans the %DR factors, ranged between 1.6% and 7.4% for the neonate, 2.9% and 8.7% for the 1-year old, 2% and 6% for the 5-year-old, 5% and 10.9% for the 10-year-old, and 10.4% and 20.7% for the adult individual. For sequential scans the corresponding %DR factors ranged between 1.3% and 6.7%, 4.5% and 11%, 4.2% and 6.6%, 6.4% and 12.3%, and 8.9% and 23.3%, respectively. Broader beam collimations are associated with decreased %DR factors, when other scanning parameters are held constant. TCM did not impair image noise. In adult patients, the %DR values were found to be in good agreement with the corresponding results obtained in the anthropomorphic adult phantom. In conclusion, on-line TCM may be considered as a valuable tool for reducing dose in routine CT examinations of pediatric and adult patients. However, the dose reduction achieved with TCM in neonates and young children was found to be lower than that obtained for adults. Therefore, on-line TCM should work as an additional means to reduce dose and should not replace other conventional means of reducing dose, especially in neonates and young children.« less

Technical assessment of a cone-beam CT scanner for otolaryngology imaging: image quality, dose, and technique protocols.

PubMed

Xu, J; Reh, D D; Carey, J P; Mahesh, M; Siewerdsen, J H

2012-08-01

As cone-beam CT (CBCT) systems dedicated to various imaging specialties proliferate, technical assessment grounded in imaging physics is important to ensuring that image quality and radiation dose are quantified, understood, and justified. This paper involves technical assessment of a new CBCT scanner (CS 9300, Carestream Health, Rochester, NY) dedicated to imaging of the ear and sinuses for applications in otolaryngology-head and neck surgery (OHNS). The results guided evaluation of technique protocols to minimize radiation dose in a manner sufficient for OHNS imaging tasks. The technical assessment focused on the imaging performance and radiation dose for each of seven technique protocols recommended by the manufacturer: three sinus protocols and four ear (temporal bone) protocols. Absolute dose was measured using techniques adapted from AAPM Task Group Report No. 111, involving three stacked 16 cm diameter acrylic cylinders (CTDI phantoms) and a 0.6 cm(3) Farmer ionization chamber to measure central and peripheral dose. The central dose (D(o)) was also measured as a function of longitudinal position (z) within and beyond the primary radiation field to assess, for example, out-of-field dose to the neck. Signal-difference-to-noise ratio (SDNR) and Hounsfield unit (HU) accuracy were assessed in a commercially available quality assurance phantom (CATPHAN module CTP404, The Phantom Laboratory, Greenwich, NY) and a custom phantom with soft-tissue-simulating plastic inserts (Gammex RMI, Madison, WI). Spatial resolution was assessed both qualitatively (a line-pair pattern, CATPHAN module CTP528) and quantitatively (modulation transfer function, MTF, measured with a wire phantom). Imaging performance pertinent to various OHNS imaging tasks was qualitatively assessed using an anthropomorphic phantom as evaluated by two experienced OHNS specialists. The technical assessment motivated a variety of modifications to the manufacturer-specified protocols to provide reduced radiation dose without compromising pertinent task-based imaging performance. The revised protocols yielded D(o) ranging 2.9-5.7 mGy, representing a ∼30% reduction in dose from the original technique chart. Out-of-field dose was ∼10% of D(o) at a distance of ∼8 cm from the field edge. Soft-tissue contrast resolution was fairly limited (water-brain SDNR ∼0.4-0.7) while high-contrast performance was reasonably good (SDNR ∼2-4 for a polystyrene insert in the CATPHAN). The scanner does not demonstrate (or claim to provide) accurate HU and exhibits a systematic error in CT number that could potentially be addressed by further calibration. The spatial resolution is ∼10-16 lp∕cm as assessed in a line-pair phantom, with MTF exceeding 10% out to ∼20 lp∕cm. Qualitative assessment by expert readers suggested limited soft-tissue visibility but excellent high-contrast (bone) visualization with isotropic spatial resolution suitable to a broad spectrum of pertinent sinus and temporal bone imaging tasks. The CBCT scanner provided spatial and contrast resolution suitable to visualization of high-contrast morphology in sinus, maxillofacial, and otologic imaging applications. Rigorous technical assessment guided revision of technique protocols to reduce radiation dose while maintaining image quality sufficient for pertinent imaging tasks. The scanner appears well suited to high-contrast sinus and temporal bone imaging at doses comparable to or less than that reported for conventional diagnostic CT of the head.

SU-F-T-519: Is Geometry Based Setup Sufficient for All of the Head and Neck Treatment Cases?: A Feasibility Study Towards the Dose Based Setup

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

Lee, S; Chen, S; Zhang, B

Purpose: This study compares the geometric-based setup (GBS) which is currently used in the clinic to a novel concept of dose-based setup (DBS) of head and neck (H&N) patients using cone beam CT (CBCT) of the day; and evaluates the clinical advantages. Methods: Ten H&N patients who underwent re-simulation and re-plan due to noticeable anatomic changes during the course of the treatments were retrospectively reviewed on dosimetric changes in the assumption of no plan modification was performed. RayStation planning system (RaySearch Laboratories AB, Sweden) was used to match (ROI fusion module) between prescribed isodoseline (IDL) in the CBCT imported alongmore » with ROIs from re-planned CT and the IDL of original plan (Dose-based setup: DBS). Then, the CBCT plan based on daily setup using the GBS (previously used for a patient) and the DBS CBCT plan recalculated in RayStation compared against the original CT-sim plan. Results: Most of patients’ tumor coverage and OAR doses got generally worsen when the CBCT plans were compared with original CT-sim plan with GBS. However, when DBS intervened, the OAR dose and tumor coverage was better than the GBS. For example, one of patients’ daily average doses of right parotid and oral cavity increased to 26% and 36%, respectively from the original plan to the GBS planning. However, it only increased by 13% and 24%, respectively with DBS. GTV D95 coverage also decreased by 16% with GBS, but only 2% decreased with DBS. Conclusion: DBS method is superior to GBS to prevent any abrupt dose changes to OARs as well as PTV/CTV or GTV at least for some H&N cases. Since it is not known when the DBS is beneficial to the GBS, a system which enables the on-line DBS may be helpful for better treatment of H&N.« less

Acceleration of intensity-modulated radiotherapy dose calculation by importance sampling of the calculation matrices.

PubMed

Thieke, Christian; Nill, Simeon; Oelfke, Uwe; Bortfeld, Thomas

2002-05-01

In inverse planning for intensity-modulated radiotherapy, the dose calculation is a crucial element limiting both the maximum achievable plan quality and the speed of the optimization process. One way to integrate accurate dose calculation algorithms into inverse planning is to precalculate the dose contribution of each beam element to each voxel for unit fluence. These precalculated values are stored in a big dose calculation matrix. Then the dose calculation during the iterative optimization process consists merely of matrix look-up and multiplication with the actual fluence values. However, because the dose calculation matrix can become very large, this ansatz requires a lot of computer memory and is still very time consuming, making it not practical for clinical routine without further modifications. In this work we present a new method to significantly reduce the number of entries in the dose calculation matrix. The method utilizes the fact that a photon pencil beam has a rapid radial dose falloff, and has very small dose values for the most part. In this low-dose part of the pencil beam, the dose contribution to a voxel is only integrated into the dose calculation matrix with a certain probability. Normalization with the reciprocal of this probability preserves the total energy, even though many matrix elements are omitted. Three probability distributions were tested to find the most accurate one for a given memory size. The sampling method is compared with the use of a fully filled matrix and with the well-known method of just cutting off the pencil beam at a certain lateral distance. A clinical example of a head and neck case is presented. It turns out that a sampled dose calculation matrix with only 1/3 of the entries of the fully filled matrix does not sacrifice the quality of the resulting plans, whereby the cutoff method results in a suboptimal treatment plan.

Tolerance doses of cutaneous and mucosal tissues in ring-necked parakeets (Psittacula krameri) for external beam megavoltage radiation.

PubMed

Barron, Heather W; Roberts, Royce E; Latimer, Kenneth S; Hernandez-Divers, Stephen; Northrup, Nicole C

2009-03-01

Currently used dosages for external-beam megavoltage radiation therapy in birds have been extrapolated from mammalian patients and often appear to provide inadequate doses of radiation for effective tumor control. To determine the tolerance doses of cutaneous and mucosal tissues of normal birds in order to provide more effective radiation treatment for tumors that have been shown to be radiation responsive in other species, ingluvial mucosa and the skin over the ingluvies of 9 ring-necked parakeets (Psittacula krameri) were irradiated in 4-Gy fractions to a total dose of either 48, 60, or 72 Gy using an isocentric cobalt-60 teletherapy unit. Minimal radiation-induced epidermal changes were present in the high-dose group histologically. Neither dose-related acute nor chronic radiation effects could be detected in any group grossly in cutaneous or mucosal tissue over a 9-month period. Radiation doses of 72 Gy in 4-Gy fractions were well tolerated in the small number of ring-necked parakeets in this initial tolerance dose study.

The Influence of Changes in Tumor Hypoxia on Dose-Painting Treatment Plans Based on {sup 18}F-FMISO Positron Emission Tomography

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

Lin Zhixiong; Mechalakos, James; Nehmeh, Sadek

2008-03-15

Purpose: To evaluate how changes in tumor hypoxia, according to serial fluorine-18-labeled fluoro-misonidazole ({sup 18}F-FMISO) positron emission tomography (PET) imaging, affect the efficacy of intensity-modulated radiotherapy (IMRT) dose painting. Methods and Materials: Seven patients with head and neck cancers were imaged twice with FMISO PET, separated by 3 days, before radiotherapy. Intensity-modulated radiotherapy plans were designed, on the basis of the first FMISO scan, to deliver a boost dose of 14 Gy to the hypoxic volume, in addition to the 70-Gy prescription dose. The same plans were then applied to hypoxic volumes from the second FMISO scan, and the efficacymore » of dose painting evaluated by assessing coverage of the hypoxic volumes using D{sub max}, D{sub min}, D{sub mean}, D{sub 95}, and equivalent uniform dose (EUD). Results: Similar hypoxic volumes were observed in the serial scans for 3 patients but dissimilar ones for the other 4. There was reduced coverage of hypoxic volumes of the second FMISO scan relative to that of the first scan (e.g., the average EUD decreased from 87 Gy to 80 Gy). The decrease was dependent on the similarity of the hypoxic volumes of the two scans (e.g., the average EUD decrease was approximately 4 Gy for patients with similar hypoxic volumes and approximately 12 Gy for patients with dissimilar ones). Conclusions: The changes in spatial distribution of tumor hypoxia, as detected in serial FMISO PET imaging, compromised the coverage of hypoxic tumor volumes achievable by dose-painting IMRT. However, dose painting always increased the EUD of the hypoxic volumes.« less

Assessment of Volumetric-Modulated Arc Therapy for Constant and Variable Dose Rates

PubMed Central

De Ornelas-Couto, Mariluz; Mihaylov, Ivaylo; Dogan, Nesrin

2017-01-01

Purpose: The aim of this study is to compare the effects of dose rate on volumetric-modulated arc therapy plans to determine optimal dose rates for prostate and head and neck (HN) cases. Materials and Methods: Ten prostate and ten HN cases were retrospectively studied. For each case, seven plans were generated: one variable dose rate (VDR) and six constant dose rate (CDR) (100–600 monitor units [MUs]/min) plans. Prescription doses were: 80 Gy to planning target volume (PTV) for the prostate cases, and 70, 60, and 54 Gy to PTV1, PTV2, and PTV3, respectively, for HN cases. Plans were normalized to 95% of the PTV and PTV1, respectively, with the prescription dose. Plans were assessed using Dose-Volume-Histogram metrics, homogeneity index, conformity index, MUs, and delivery time. Results: For the prostate cases, significant differences were found for rectum D35 between VDR and all CDR plans, except CDR500. Furthermore, VDR was significantly different than CDR100 and 200 for bladder D50. Delivery time for all CDR plans and MUs for CDR400–600 were significantly higher when compared to VDR. HN cases showed significant differences between VDR and CDR100, 500 and 600 for D2 to the cord and brainstem. Significant differences were found for delivery time and MUs for all CDR plans, except CDR100 for number of MUs. Conclusion: The most significant differences were observed in delivery time and number of MUs. All-in-all, the best CDR for prostate cases was found to be 300 MUs/min and 200 or 300 MUs/min for HN cases. However, VDR plans are still the choice in terms of MU efficiency and plan quality. PMID:29296033

SU-E-T-539: Fixed Versus Variable Optimization Points in Combined-Mode Modulated Arc Therapy Planning

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

Kainz, K; Prah, D; Ahunbay, E

2014-06-01

Purpose: A novel modulated arc therapy technique, mARC, enables superposition of step-and-shoot IMRT segments upon a subset of the optimization points (OPs) of a continuous-arc delivery. We compare two approaches to mARC planning: one with the number of OPs fixed throughout optimization, and another where the planning system determines the number of OPs in the final plan, subject to an upper limit defined at the outset. Methods: Fixed-OP mARC planning was performed for representative cases using Panther v. 5.01 (Prowess, Inc.), while variable-OP mARC planning used Monaco v. 5.00 (Elekta, Inc.). All Monaco planning used an upper limit of 91more » OPs; those OPs with minimal MU were removed during optimization. Plans were delivered, and delivery times recorded, on a Siemens Artiste accelerator using a flat 6MV beam with 300 MU/min rate. Dose distributions measured using ArcCheck (Sun Nuclear Corporation, Inc.) were compared with the plan calculation; the two were deemed consistent if they agreed to within 3.5% in absolute dose and 3.5 mm in distance-to-agreement among > 95% of the diodes within the direct beam. Results: Example cases included a prostate and a head-and-neck planned with a single arc and fraction doses of 1.8 and 2.0 Gy, respectively. Aside from slightly more uniform target dose for the variable-OP plans, the DVHs for the two techniques were similar. For the fixed-OP technique, the number of OPs was 38 and 39, and the delivery time was 228 and 259 seconds, respectively, for the prostate and head-and-neck cases. For the final variable-OP plans, there were 91 and 85 OPs, and the delivery time was 296 and 440 seconds, correspondingly longer than for fixed-OP. Conclusion: For mARC, both the fixed-OP and variable-OP approaches produced comparable-quality plans whose delivery was successfully verified. To keep delivery time per fraction short, a fixed-OP planning approach is preferred.« less

[Statistical process control applied to intensity modulated radiotherapy pretreatment controls with portal dosimetry].

PubMed

Villani, N; Gérard, K; Marchesi, V; Huger, S; François, P; Noël, A

2010-06-01

The first purpose of this study was to illustrate the contribution of statistical process control for a better security in intensity modulated radiotherapy (IMRT) treatments. This improvement is possible by controlling the dose delivery process, characterized by pretreatment quality control results. So, it is necessary to put under control portal dosimetry measurements (currently, the ionisation chamber measurements were already monitored by statistical process control thanks to statistical process control tools). The second objective was to state whether it is possible to substitute ionisation chamber with portal dosimetry in order to optimize time devoted to pretreatment quality control. At Alexis-Vautrin center, pretreatment quality controls in IMRT for prostate and head and neck treatments were performed for each beam of each patient. These controls were made with an ionisation chamber, which is the reference detector for the absolute dose measurement, and with portal dosimetry for the verification of dose distribution. Statistical process control is a statistical analysis method, coming from industry, used to control and improve the studied process quality. It uses graphic tools as control maps to follow-up process, warning the operator in case of failure, and quantitative tools to evaluate the process toward its ability to respect guidelines: this is the capability study. The study was performed on 450 head and neck beams and on 100 prostate beams. Control charts, showing drifts, both slow and weak, and also both strong and fast, of mean and standard deviation have been established and have shown special cause introduced (manual shift of the leaf gap of the multileaf collimator). Correlation between dose measured at one point, given with the EPID and the ionisation chamber has been evaluated at more than 97% and disagreement cases between the two measurements were identified. The study allowed to demonstrate the feasibility to reduce the time devoted to pretreatment controls, by substituting the ionisation chamber's measurements with those performed with EPID, and also that a statistical process control monitoring of data brought security guarantee. 2010 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

Semiautomated head-and-neck IMRT planning using dose warping and scaling to robustly adapt plans in a knowledge database containing potentially suboptimal plans

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

Schmidt, Matthew, E-mail: matthew.schmidt@varian.com; Grzetic, Shelby; Lo, Joseph Y.

Purpose: Prior work by the authors and other groups has studied the creation of automated intensity modulated radiotherapy (IMRT) plans of equivalent quality to those in a patient database of manually created clinical plans; those database plans provided guidance on the achievable sparing to organs-at-risk (OARs). However, in certain sites, such as head-and-neck, the clinical plans may not be sufficiently optimized because of anatomical complexity and clinical time constraints. This could lead to automated plans that suboptimally exploit OAR sparing. This work investigates a novel dose warping and scaling scheme that attempts to reduce effects of suboptimal sparing in clinicalmore » database plans, thus improving the quality of semiautomated head-and-neck cancer (HNC) plans. Methods: Knowledge-based radiotherapy (KBRT) plans for each of ten “query” patients were semiautomatically generated by identifying the most similar “match” patient in a database of 103 clinical manually created patient plans. The match patient’s plans were adapted to the query case by: (1) deforming the match beam fluences to suit the query target volume and (2) warping the match primary/boost dose distribution to suit the query geometry and using the warped distribution to generate query primary/boost optimization dose-volume constraints. Item (2) included a distance scaling factor to improve query OAR dose sparing with respect to the possibly suboptimal clinical match plan. To further compensate for a component plan of the match case (primary/boost) not optimally sparing OARs, the query dose volume constraints were reduced using a dose scaling factor to be the minimum from either (a) the warped component plan (primary or boost) dose distribution or (b) the warped total plan dose distribution (primary + boost) scaled in proportion to the ratio of component prescription dose to total prescription dose. The dose-volume constraints were used to plan the query case with no human intervention to adjust constraints during plan optimization. Results: KBRT and original clinical plans were dosimetrically equivalent for parotid glands (mean/median doses), spinal cord, and brainstem (maximum doses). KBRT plans significantly reduced larynx median doses (21.5 ± 6.6 Gy to 17.9 ± 3.9 Gy), and oral cavity mean (32.3 ± 6.2 Gy to 28.9 ± 5.4 Gy) and median (28.7 ± 5.7 Gy to 23.2 ± 5.3 Gy) doses. Doses to ipsilateral parotid gland, larynx, oral cavity, and brainstem were lower or equivalent in the KBRT plans for the majority of cases. By contrast, KBRT plans generated without the dose warping and dose scaling steps were not significantly different from the clinical plans. Conclusions: Fast, semiautomatically generated HNC IMRT plans adapted from existing plans in a clinical database can be of equivalent or better quality than manually created plans. The reductions in OAR doses in the semiautomated plans, compared to the clinical plans, indicate that the proposed dose warping and scaling method shows promise in mitigating the impact of suboptimal clinical plans.« less

Intensity Modulated Radiotherapy (IMRT) in head and neck cancers - an overview.

PubMed

Nutting, C M

2012-07-01

Radiotherapy (RT) is effective in head and neck cancers. Following RT, dryness and dysphagia are the 2 major sequelae which alter the quality of life (QOL) significantly in these patients. There is randomized evidence that Intensity Modulated Radiotherapy (IMRT) effectively spares the parotid glands. IMRT has been attempted in all head and neck subsites with encouraging results (discussed below). Role of IMRT in swallowing structure (constrictor muscles) sparing is less clear.Further improvement in results may be possible by using functional imaging at the time of RT planning and by image guidance/verification at the time of treatment delivery. The following text discusses these issues in detail. Head and neck cancer, IMRT.

Impact of total radiotherapy dose on survival for head and neck Merkel cell carcinoma after resection.

PubMed

Patel, Sagar A; Qureshi, Muhammad M; Mak, Kimberley S; Sahni, Debjani; Giacalone, Nicholas J; Ezzat, Waleed; Jalisi, Scharukh; Truong, Minh Tam

2017-07-01

Head and neck Merkel cell carcinoma (MCC) is commonly treated with surgery and adjuvant radiotherapy (RT) for high-risk features. The optimal radiation dose is unknown. One thousand six hundred twenty-five eligible patients with head and neck MCC were identified in the National Cancer Data Base (NCDB). Radiation dose was divided into 3 groups: 30 to <50 Gray (Gy), 50-55 Gy, and >55-70 Gy. Cox regression was used to compare overall survival (OS) between groups, accounting for age, sex, stage, surgery type, margin status, comorbidities, and use of chemotherapy. With a median follow-up of 33.5 months, 3-year OS was 48.9%, 70.3%, and 58.7% for 30 to <50 Gy, 50-55 Gy, and >55-70 Gy, respectively (P < .001). Compared to 50-55 Gy, doses between 30 to <50 Gy (adjusted hazard ratio [HR] 1.53; 95% confidence interval [CI] 1.17-1.99; P = .002) and >55-70 Gy (adjusted HR 1.21; 95% CI 1.0-1.46; P = .06) were associated with worse survival. Adjuvant radiation doses within 50-55 Gy may be optimal for head and neck MCC. © 2017 Wiley Periodicals, Inc.

Radiation Dose Reduction by Indication-Directed Focused z-Direction Coverage for Neck CT.

PubMed

Parikh, A K; Shah, C C

2016-06-01

The American College of Radiology-American Society of Neuroradiology-Society for Pediatric Radiology Practice Parameter for a neck CT suggests that coverage should be from the sella to the aortic arch. It also recommends using CT scans judiciously to achieve the clinical objective. Our purpose was to analyze the potential dose reduction by decreasing the scan length of a neck CT and to assess for any clinically relevant information that might be missed from this modified approach. This retrospective study included 126 children who underwent a neck CT between August 1, 2013, and September 30, 2014. Alteration of the scan length for the modified CT was suggested on the topographic image on the basis of the indication of the study, with the reader blinded to the images and the report. The CT dose index volume of the original scan was multiplied by the new scan length to calculate the dose-length product of the modified study. The effective dose was calculated for the original and modified studies by using age-based conversion factors from the American Association of Physicists in Medicine Report No. 96. Decreasing the scan length resulted in an average estimated dose reduction of 47%. The average reduction in scan length was 10.4 cm, decreasing the overall coverage by 48%. The change in scan length did not result in any missed findings that altered management. Of the 27 abscesses in this study, none extended to the mediastinum. All of the lesions in question were completely covered. Decreasing the scan length of a neck CT according to the indication provides a significant savings in radiation dose, while not altering diagnostic ability or management. © 2016 by American Journal of Neuroradiology.

Cumulative cisplatin dose in concurrent chemoradiotherapy for head and neck cancer: A systematic review.

PubMed

Strojan, Primož; Vermorken, Jan B; Beitler, Jonathan J; Saba, Nabil F; Haigentz, Missak; Bossi, Paolo; Worden, Francis P; Langendijk, Johannes A; Eisbruch, Avraham; Mendenhall, William M; Lee, Anne W M; Harrison, Louis B; Bradford, Carol R; Smee, Robert; Silver, Carl E; Rinaldo, Alessandra; Ferlito, Alfio

2016-04-01

The optimal cumulative dose and timing of cisplatin administration in various concurrent chemoradiotherapy protocols for nonmetastatic head and neck squamous cell carcinoma (HNSCC) has not been determined. The absolute survival benefit at 5 years of concurrent chemoradiotherapy protocols versus radiotherapy alone observed in prospective randomized trials reporting on the use of cisplatin monochemotherapy for nonnasopharyngeal HNSCC was extracted. In the case of nonrandomized studies, the outcome results at 2 years were compared between groups of patients receiving different cumulative cisplatin doses. Eleven randomized trials and 7 nonrandomized studies were identified. In 6 definitive radiotherapy phase III trials, a statistically significant association (p = .027) between cumulative cisplatin dose, independent of the schedule, and overall survival benefit was observed for higher doses. Results support the conclusion that the cumulative dose of cisplatin in concurrent chemoradiation protocols for HNSCC has a significant positive correlation with survival. © 2015 Wiley Periodicals, Inc. Head Neck 38: E2151-E2158, 2016. © 2015 Wiley Periodicals, Inc.

Incidental findings in multislice computed tomography prior to transcatheter aortic valve implantation: frequency, clinical relevance and outcome.

PubMed

Trenkwalder, Teresa; Lahmann, Anna Lena; Nowicka, Magdalena; Pellegrini, Costanza; Rheude, Tobias; Mayr, N Patrick; Voss, Stephanie; Bleiziffer, Sabine; Lange, Rüdiger; Joner, Michael; Kasel, Albert M; Kastrati, Adnan; Schunkert, Heribert; Husser, Oliver; Hadamitzky, Martin; Hengstenberg, Christian

2018-02-21

Multislice computed tomography (MSCT) has emerged as the mainstay in patients planned for transcatheter aortic valve implantation (TAVI). Incidental findings (IF) in MSCT are common. However, the exact incidence, clinical relevance and further consequences of IF are unclear and it is controversial whether IF adversely affect patients' outcome. We analyzed MSCT data of 1050 patients screened for TAVI between January 2011 and December 2014. Median follow-up of patients was 20 months. In total, 3194 IF were identified, which were classified into clinically non-relevant IF (2872, 90%) and clinically relevant IF (322, 10%). In 25% of patients (258/1050) at least one clinically relevant IF was present. Age (80 ± 7 vs. 80 ± 7 years; p = 0.198) and EuroSCORE II (3.6% [2.1-5.7] vs. 3.6% [2.1-5.9]; p = 0.874) was similar between patients with and without a clinically relevant IF. TAVI was performed less frequently in patients with a clinically relevant IF (76% vs. 85%; p < 0.001), with more patients receiving surgical aortic valve replacement in that group (14% vs. 11%; p = 0.042), possibly due to the high rate of incidental aneurysms of the ascending aorta (n = 48). If TAVI was performed mortality did not differ (30-days: 4% vs. 3%; p = 0.339, 1-year: 11% vs. 14%; p = 0.226) between patients with and without a clinically relevant IF. Our study is the largest study to analyze prevalence, clinical relevance and therapeutic consequences of IF during screening for TAVI. IF in pre-procedural MSCT are common and clinically relevant in one-quarter of patients. However, these findings had no impact on overall mortality.

Lipomatous hypertrophy of the interatrial septum in ECG-gated multislice computed tomography of the heart.

PubMed

Czekajska-Chehab, Elżbieta; Tomaszewska, Monika; Olchowik, Grażyna; Tomaszewski, Marek; Adamczyk, Piotr; Drop, Andrzej

2012-07-01

Lipomatous hypertrophy of the interatrial septum (LHIS) is a benign disorder characterized by fat accumulation in the interatrial septum (IAS). The purpose of the study was to analyze the incidental detection of LHIS in patients with various clinical conditions, referred to ECG-gated multislice computed tomography (ECG-MSCT) examinations of the heart. The ECG-MSCT examinations of 5786 patients (2839 women; 2947 men), were analyzed. The examinations were performed using 8-row (1015 patients) and 64-row (4771 patients) MSCT, in pre- and postcontrast scanning. We analyzed the shape of the IAS, density and maximal thickness of IAS, the thickness of the epicardial adipose tissue, and the degree of contact of IAS with the ascending aorta and superior vena cava. We also determined body mass index (BMI) in patients with LHIS. LHIS was detected in 56 (0.96%) patients, with an average age of 61.5±9.8 years. The mean BMI in the analyzed group was 30.1±4.86. During the end-diastolic phase the thickness of IAS was significantly higher (p<0.0001), and on average equaled 18.3 mm. The mean optical density of the IAS was conspicuously higher (p<0.0001) in post-contrast phase than in pre-contrast phase. The thickness of the epicardial adipose tissue in the region of the left atrioventricular groove was on average 15 mm. In all cases the dumbbell shape of IAS was observed. The incidental frequency of LHIS occurrence in patients diagnosed with the ECG-MSCT examinations is about 1%. In most subjects it is linked with a higher BMI and increased thickness of the epicardial adipose tissue.

Clinical accuracy of a patient-specific femoral osteotomy guide in minimally-invasive posterior hip arthroplasty.

PubMed

Schneider, Adrian K; Pierrepont, Jim W; Hawdon, Gabrielle; McMahon, Stephen

2018-04-01

Patient specific guides can be a valuable tool in improving the precision of planned femoral neck osteotomies, especially in minimally invasive hip surgery, where bony landmarks are often inaccessible. The aim of our study was to validate the accuracy of a novel patient specific femoral osteotomy guide for THR through a minimally invasive posterior approach, the direct superior approach (DSA). As part of our routine preoperative planning 30 patients underwent low dose CT scans of their arthritic hip. 3D printed patient specific femoral neck osteotomy guides were then produced. Intraoperatively, having cleared all soft tissue from the postero-lateral neck of the enlocated hip, the guide was placed and pinned onto the posterolateral femoral neck. The osteotomy was performed using an oscillating saw and the uncemented hip components were implanted as per routine. Postoperatively, the achieved level of the osteotomy at the medial calcar was compared with the planned level of resection using a 3D/2D matching analysis (Mimics X-ray module, Materialise, Belgium). A total of 30 patients undergoing uncemented Trinity™ acetabular and TriFit TS™ femoral component arthroplasty (Corin, UK) were included in our analysis. All but one of our analysed osteotomies were found to be within 3 mm from the planned height of osteotomy. In one patient the level of osteotomy deviated 5 mm below the planned level of resection. Preoperative planning and the use of patient specific osteotomy guides provides an accurate method of performing femoral neck osteotomies in minimally invasive hip arthroplasty using the direct superior approach. IV (Case series).

Swallowing outcomes following Intensity Modulated Radiation Therapy (IMRT) for head & neck cancer - a systematic review.

PubMed

Roe, Justin W G; Carding, Paul N; Dwivedi, Raghav C; Kazi, Rehan A; Rhys-Evans, Peter H; Harrington, Kevin J; Nutting, Christopher M

2010-10-01

A systematic review to establish what evidence is available for swallowing outcomes following IMRT for head and neck cancer. Online electronic databases were searched to identify papers published in English from January 1998 to December 2009. Papers were independently appraised by two reviewers for methodological quality, method of swallowing evaluation and categorized according to the World Health Organisation's International Classification of Health Functions. The impact of radiation dose to dysphagia aspiration risk structures (DARS) was also evaluated. Sixteen papers met the inclusion criteria. The literature suggests that limiting the radiation dose to certain structures may result in favourable swallowing outcomes. Methodological limitations included variable assessment methods and outcome measures and heterogeneity of patients. There are only limited prospective data, especially where pre-treatment measures have been taken and compared to serial post-treatment assessment. Few studies have investigated the impact of IMRT on swallow function and the impact on everyday life. Initial studies have reported potential benefits but are limited in terms of study design and outcome data. Further well designed, prospective, longitudinal swallowing studies including multidimensional evaluation methods are required to enable a more comprehensive understanding of dysphagia complications and inform pre-treatment counselling and rehabilitation planning. Copyright © 2010 Elsevier Ltd. All rights reserved.

Multifield optimization intensity modulated proton therapy for head and neck tumors: a translation to practice.

PubMed

Frank, Steven J; Cox, James D; Gillin, Michael; Mohan, Radhe; Garden, Adam S; Rosenthal, David I; Gunn, G Brandon; Weber, Randal S; Kies, Merrill S; Lewin, Jan S; Munsell, Mark F; Palmer, Matthew B; Sahoo, Narayan; Zhang, Xiaodong; Liu, Wei; Zhu, X Ronald

2014-07-15

We report the first clinical experience and toxicity of multifield optimization (MFO) intensity modulated proton therapy (IMPT) for patients with head and neck tumors. Fifteen consecutive patients with head and neck cancer underwent MFO-IMPT with active scanning beam proton therapy. Patients with squamous cell carcinoma (SCC) had comprehensive treatment extending from the base of the skull to the clavicle. The doses for chemoradiation therapy and radiation therapy alone were 70 Gy and 66 Gy, respectively. The robustness of each treatment plan was also analyzed to evaluate sensitivity to uncertainties associated with variations in patient setup and the effect of uncertainties with proton beam range in patients. Proton beam energies during treatment ranged from 72.5 to 221.8 MeV. Spot sizes varied depending on the beam energy and depth of the target, and the scanning nozzle delivered the spot scanning treatment "spot by spot" and "layer by layer." Ten patients presented with SCC and 5 with adenoid cystic carcinoma. All 15 patients were able to complete treatment with MFO-IMPT, with no need for treatment breaks and no hospitalizations. There were no treatment-related deaths, and with a median follow-up time of 28 months (range, 20-35 months), the overall clinical complete response rate was 93.3% (95% confidence interval, 68.1%-99.8%). Xerostomia occurred in all 15 patients as follows: grade 1 in 10 patients, grade 2 in 4 patients, and grade 3 in 1 patient. Mucositis within the planning target volumes was seen during the treatment of all patients: grade 1 in 1 patient, grade 2 in 8 patients, and grade 3 in 6 patients. No patient experienced grade 2 or higher anterior oral mucositis. To our knowledge, this is the first clinical report of MFO-IMPT for head and neck tumors. Early clinical outcomes are encouraging and warrant further investigation of proton therapy in prospective clinical trials. Copyright © 2014 Elsevier Inc. All rights reserved.

Optimized volumetric modulated arc therapy versus 3D-CRT for early stage mediastinal Hodgkin lymphoma without axillary involvement: a comparison of second cancers and heart disease risk.

PubMed

Filippi, Andrea Riccardo; Ragona, Riccardo; Piva, Cristina; Scafa, Davide; Fiandra, Christian; Fusella, Marco; Giglioli, Francesca Romana; Lohr, Frank; Ricardi, Umberto

2015-05-01

The purpose of this study was to evaluate the risks of second cancers and cardiovascular diseases associated with an optimized volumetric modulated arc therapy (VMAT) planning solution in a selected cohort of stage I/II Hodgkin lymphoma (HL) patients treated with either involved-node or involved-site radiation therapy in comparison with 3-dimensional conformal radiation therapy (3D-CRT). Thirty-eight patients (13 males and 25 females) were included. Disease extent was mediastinum alone (n=8, 21.1%); mediastinum plus unilateral neck (n=19, 50%); mediastinum plus bilateral neck (n=11, 29.9%). Prescription dose was 30 Gy in 2-Gy fractions. Only 5 patients had mediastinal bulky disease at diagnosis (13.1%). Anteroposterior 3D-CRT was compared with a multiarc optimized VMAT solution. Lung, breast, and thyroid cancer risks were estimated by calculating a lifetime attributable risk (LAR), with a LAR ratio (LAR(VMAT)-to-LAR(3D-CRT)) as a comparative measure. Cardiac toxicity risks were estimated by calculating absolute excess risk (AER). The LAR ratio favored 3D-CRT for lung cancer induction risk in mediastinal alone (P=.004) and mediastinal plus unilateral neck (P=.02) presentations. LAR ratio for breast cancer was lower for VMAT in mediastinal plus bilateral neck presentations (P=.02), without differences for other sites. For thyroid cancer, no significant differences were observed, regardless of anatomical presentation. A significantly lower AER of cardiac (P=.038) and valvular diseases (P<.0001) was observed for VMAT regardless of disease extent. In a cohort of patients with favorable characteristics in terms of disease extent at diagnosis (large prevalence of nonbulky presentations without axillary involvement), optimized VMAT reduced heart disease risk with comparable risks of thyroid and breast cancer, with an increase in lung cancer induction probability. The results are however strongly influenced by the different anatomical presentations, supporting an individualized approach. Copyright © 2015 Elsevier Inc. All rights reserved.

Patterns of Recurrence in Electively Irradiated Lymph Node Regions After Definitive Accelerated Intensity Modulated Radiation Therapy for Head and Neck Squamous Cell Carcinoma

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

Bosch, Sven van den, E-mail: sven.vandenbosch@radboudumc.nl; Dijkema, Tim; Verhoef, Lia C.G.

Purpose: To provide a comprehensive risk assessment on the patterns of recurrence in electively irradiated lymph node regions after definitive radiation therapy for head and neck cancer. Methods and Materials: Two hundred sixty-four patients with stage cT2-4N0-2M0 squamous cell carcinoma of the oropharynx, larynx, or hypopharynx treated with accelerated intensity modulated radiation therapy between 2008 and 2012 were included. On the radiation therapy planning computed tomography (CT) scans from all patients, 1166 lymph nodes (short-axis diameter ≥5 mm) localized in the elective volume were identified and delineated. The exact sites of regional recurrences were reconstructed and projected on the initial radiationmore » therapy planning CT scan by performing coregistration with diagnostic imaging of the recurrence. Results: The actuarial rate of recurrence in electively irradiated lymph node regions at 2 years was 5.1% (95% confidence interval 2.4%-7.8%). Volumetric analysis showed an increased risk of recurrence with increasing nodal volume. Receiver operating characteristic analysis demonstrated that the summed long- and short-axis diameter is a good alternative for laborious volume calculations, using ≥17 mm as cut-off (hazard ratio 17.8; 95% confidence interval 5.7-55.1; P<.001). Conclusions: An important risk factor was identified that can help clinicians in the pretreatment risk assessment of borderline-sized lymph nodes. Not overtly pathologic nodes with a summed diameter ≥17 mm may require a higher than elective radiation therapy dose. For low-risk elective regions (all nodes <17 mm), the safety of dose de-escalation below the traditional 45 to 50 Gy should be investigated.« less

Effects of omitting elective neck irradiation to nodal Level IB in nasopharyngeal carcinoma patients with negative Level IB lymph nodes treated by intensity-modulated radiotherapy: a Phase 2 study.

PubMed

Li, Mei; Huang, Xiao-Guang; Yang, Zhi-Ning; Lu, Jia-Yang; Zhan, Yi-Zhou; Xie, Wen-Jia; Zhou, Dong-Jie; Wang, Li; Zhu, Di-Xia; Lin, Zhi-Xiong

2016-09-01

To investigate the need for elective neck irradiation (ENI) to nodal Level IB in patients with nasopharyngeal carcinoma (NPC) with negative Level IB lymph nodes (IB-negative) treated by intensity-modulated radiotherapy (IMRT). We conducted a Phase 2 prospective study in 123 newly diagnosed IB-negative patients with NPC treated by IMRT, who met at least 1 of the following criteria: (1) unilateral or bilateral Level II involvement with 1 of the following: Level IIA involvement or any Level II node ≥2 cm/with extracapsular spread; (2) ≥2 unilateral node-positive regions. Bilateral Level IB nodes were not contoured as part of the treatment target and treated electively. Level IB regional recurrence rate; pattern of treatment failure; 3-year overall survival (3y-OS), 3-year local control (3y-LC) and 3-year regional control (3y-RC) rates; toxicities; and dosimetric data for planning target volumes, organs at risk, Level IB and submandibular glands (SMGs) were evaluated. Two patients developed failures at Level IB (1.6%). The 3y-LC, 3y-RC and 3y-OS rates were 93.5%, 93.5% and 78.0%, respectively. Bilateral Level IB received unplanned high-dose irradiation with a mean dose (Dmean) ≥50 Gy in 60% of patients. The average Dmean of bilateral SMGs was approximately 53 Gy. ENI to Level IB may be unnecessary in IB-negative patients with NPC treated by IMRT. A further Phase 3 study is warranted. Based on the results of this first Phase 2 study, we suggest omitting ENI to Level IB in Ib-negative patients with NPC with extensive nodal disease treated by IMRT.

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

Giaddui, T; Hardin, M; Keller, J

Purpose: To evaluate patient specific quality assurance (PSQA) for the delivery of volumetric modulated arc therapy (VMAT) by disease site. To compare planning-delivery system (PDS) PSQA pass rates in a dual vendor institution. Methods: PSQA is performed for VMAT plans using a ScandiDos Delta4 phantom. Verification plans are calculated using Varian Eclipse and Elekta Monaco treatment planning systems (TPS) for patients treated using Varian Truebeam and Elekta linear accelerators respectively. Individual arcs are delivered to the Delta4 phantoms and assessed using the gamma index pass criterion(3% Dose Deviation(DD%), 3mm Distance to Agreement(DTA),10% dose threshold and 90% gamma index). Results: Amore » total of 287 VMAT plans and 680 arcs were analyzed. The passing rates for VMAT QA plans were 95% and 98% for head/neck and pelvis/prostate plans respectively, and 100% for chest/abdomen, spine, lung Stereotactic Body Radiotherapy (SBRT) and Stereotactic Radiosurgery(SRS) plans. Average gamma indices were: (99 ± 2) % for pelvis/prostate, chest/abdomen and lung SBRT plans, (97 ± 4) % for head and neck plans and (98 ± 3) % for spine plans. The average DD% and DTA pass rates ranged from 82% to 90% and 98% to 99% respectively for plans in different disease sites. Paired t-test analysis (two tails) indicated no significant differences in the gamma indices between plans delivered using different PDS; the P values were: 0.08, 0.45, and 0.94 for lung SBRT, head/neck and pelvis/prostate plans respectively. The statistical power for comparing PDS in different disease sites with an alpha of 0.05 is 1. Conclusion: The Gamma indices based on 3% DD%, 3 mm DTA and 10% dose threshold for the VMAT QA plans in all disease sites were well above 90%, suggesting the possibility of using a more stringent PSQA criterion. No significant differences were observed in the QA of VMAT plans delivered using different PDS.« less

Dependence of Achievable Plan Quality on Treatment Technique and Planning Goal Refinement: A Head-and-Neck Intensity Modulated Radiation Therapy Application

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

Qi, X. Sharon, E-mail: xqi@mednet.ucla.edu; Ruan, Dan; Lee, Steve P.

2015-03-15

Purpose: To develop a practical workflow for retrospectively analyzing target and normal tissue dose–volume endpoints for various intensity modulated radiation therapy (IMRT) delivery techniques; to develop technique-specific planning goals to improve plan consistency and quality when feasible. Methods and Materials: A total of 165 consecutive head-and-neck patients from our patient registry were selected and retrospectively analyzed. All IMRT plans were generated using the same dose–volume guidelines for TomoTherapy (Tomo, Accuray), TrueBeam (TB, Varian) using fixed-field IMRT (TB-IMRT) or RAPIDARC (TB-RAPIDARC), or Siemens Oncor (Siemens-IMRT, Siemens). A MATLAB-based dose–volume extraction and analysis tool was developed to export dosimetric endpoints for eachmore » patient. With a fair stratification of patient cohort, the variation of achieved dosimetric endpoints was analyzed among different treatment techniques. Upon identification of statistically significant variations, technique-specific planning goals were derived from dynamically accumulated institutional data. Results: Retrospective analysis showed that although all techniques yielded comparable target coverage, the doses to the critical structures differed. The maximum cord doses were 34.1 ± 2.6, 42.7 ± 2.1, 43.3 ± 2.0, and 45.1 ± 1.6 Gy for Tomo, TB-IMRT, TB-RAPIDARC, and Siemens-IMRT plans, respectively. Analyses of variance showed significant differences for the maximum cord doses but no significant differences for other selected structures among the investigated IMRT delivery techniques. Subsequently, a refined technique-specific dose–volume guideline for maximum cord dose was derived at a confidence level of 95%. The dosimetric plans that failed the refined technique-specific planning goals were reoptimized according to the refined constraints. We observed better cord sparing with minimal variations for the target coverage and other organ at risk sparing for the Tomo cases, and higher parotid doses for C-arm linear accelerator–based IMRT and RAPIDARC plans. Conclusion: Patient registry–based processes allowed easy and systematic dosimetric assessment of treatment plan quality and consistency. Our analysis revealed the dependence of certain dosimetric endpoints on the treatment techniques. Technique-specific refinement of planning goals may lead to improvement in plan consistency and plan quality.« less

Feasibility study on dosimetry verification of volumetric-modulated arc therapy-based total marrow irradiation.

PubMed

Liang, Yun; Kim, Gwe-Ya; Pawlicki, Todd; Mundt, Arno J; Mell, Loren K

2013-03-04

The purpose of this study was to develop dosimetry verification procedures for volumetric-modulated arc therapy (VMAT)-based total marrow irradiation (TMI). The VMAT based TMI plans were generated for three patients: one child and two adults. The planning target volume (PTV) was defined as bony skeleton, from head to mid-femur, with a 3 mm margin. The plan strategy similar to published studies was adopted. The PTV was divided into head and neck, chest, and pelvic regions, with separate plans each of which is composed of 2-3 arcs/fields. Multiple isocenters were evenly distributed along the patient's axial direction. The focus of this study is to establish a dosimetry quality assurance procedure involving both two-dimensional (2D) and three-dimensional (3D) volumetric verifications, which is desirable for a large PTV treated with multiple isocenters. The 2D dose verification was performed with film for gamma evaluation and absolute point dose was measured with ion chamber, with attention to the junction between neighboring plans regarding hot/cold spots. The 3D volumetric dose verification used commercial dose reconstruction software to reconstruct dose from electronic portal imaging devices (EPID) images. The gamma evaluation criteria in both 2D and 3D verification were 5% absolute point dose difference and 3 mm of distance to agreement. With film dosimetry, the overall average gamma passing rate was 98.2% and absolute dose difference was 3.9% in junction areas among the test patients; with volumetric portal dosimetry, the corresponding numbers were 90.7% and 2.4%. A dosimetry verification procedure involving both 2D and 3D was developed for VMAT-based TMI. The initial results are encouraging and warrant further investigation in clinical trials.

DEMAT: A multi-institutional dosimetry audit of rotational and static intensity-modulated radiotherapy.

PubMed

Lafond, Caroline; Chiavassa, Sophie; Bertaut, Cindy; Boussion, Nicolas; Chapel, Nathalie; Chapron, Lucie; Coste, Frédéric; Crespin, Sylvain; Dy, Gilles; Faye, Papa Abdoulaye; Leleu, Cyril; Bouvier, Jeanne; Madec, Ludovic; Mesgouez, Jérôme; Palisson, Jérémy; Vela, Anthony; Delpon, Grégory

2016-05-01

Static beam intensity-modulated-radiation-therapy (IMRT) and/or Volumetric-Modulated-Arc-Therapy (VMAT) are now available in many regional radiotherapy departments. The aim of this multi-institutional audit was to design a new methodology based on radiochromic films to perform an independent quality control. A set of data were sent to all participating centres for two clinical localizations: prostate and Head and Neck (H&N) cancers. The agreement between calculations and measurements was verified in the Octavius phantom (PTW) by point measurements using ionization chambers and by 2D measurements using EBT3 radiochromic films. Due to uncertainties in the whole procedure, criteria were set to 5% and 3% in local dose and 3mm in distance excluding doses lower than 10% of the maximum doses. No normalization point or area was used for the quantitative analysis. 13 radiotherapy centres participated in this audit involving 28 plans (12 IMRT, 16 VMAT). For point measurements, mean errors were -0.18±1.54% and 0.00±1.58% for prostate and H&N cases respectively. For 2D measurements with 5%/3mm criteria, gamma map analysis showed a pixel pass rate higher than 95% for prostate and H&N. Mean gamma index was lower than 0.4 for prostate and 0.5 for H&N. Both techniques yielded similar results. This study showed the feasibility of an independent quality control by peers for conventional IMRT and VMAT. Results from all participating centres were found to be in good agreement. This regional study demonstrated the feasibility of our new methodology based on radiochromic films without dose normalization on a specific point. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Forensic veterinary radiology: ballistic-radiological 3D computertomographic reconstruction of an illegal lynx shooting in Switzerland.

PubMed

Thali, Michael J; Kneubuehl, Beat P; Bolliger, Stephan A; Christe, Andreas; Koenigsdorfer, Urs; Ozdoba, Christoph; Spielvogel, Elke; Dirnhofer, Richard

2007-08-24

The lynx, which was reintroduced to Switzerland after being exterminated at the beginning of the 20th century, is protected by Swiss law. However, poaching occurs from time to time, which makes criminal investigations necessary. In the presented case, an illegally shot lynx was examined by conventional plane radiography and three-dimensional multislice computertomography (3D MSCT), of which the latter yielded superior results with respect to documentation and reconstruction of the inflicted gunshot wounds. We believe that 3D MSCT, already described in human forensic-pathological cases, is also a suitable and promising new technique for veterinary pathology.

[The use of an opect optic system in neurosurgical practice].

PubMed

Kalinovskiy, A V; Rzaev, D A; Yoshimitsu, K

2018-01-01

Modern neurosurgical practice is impossible without access to various information sources. The use of MRI and MSCT data during surgery is an integral part of the neurosurgeon's daily practice. Devices capable of managing an image viewer system without direct contact with equipment simplify working in the operating room. To test operation of a non-contact MRI and MSCT image viewer system in the operating room and to evaluate the system effectiveness. An Opect non-contact image management system developed at the Tokyo Women's Medical University was installed in one of the operating rooms of the Novosibirsk Federal Center of Neurosurgery in 2014. In 2015, the Opect system was used by operating surgeons in 73 surgeries performed in the same operating room. The system effectiveness was analyzed based on a survey of surgeons. The non-contact image viewer system occurred to be easy-to-learn for the personnel to operate this system, easy-to-manage it, and easy-to-present visual information during surgery. Application of the Opect system simplifies work with neuroimaging data during surgery. The surgeon can independently view series of relevant MRI and MSCT scans without any assistance.

Three-Dimensional Dosimetric Validation of a Magnetic Resonance Guided Intensity Modulated Radiation Therapy System

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

Rankine, Leith J., E-mail: Leith_Rankine@med.unc.edu; Department of Radiation Oncology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Mein, Stewart

Purpose: To validate the dosimetric accuracy of a commercially available magnetic resonance guided intensity modulated radiation therapy (MRgIMRT) system using a hybrid approach: 3-dimensional (3D) measurements and Monte Carlo calculations. Methods and Materials: We used PRESAGE radiochromic plastic dosimeters with remote optical computed tomography readout to perform 3D high-resolution measurements, following a novel remote dosimetry protocol. We followed the intensity modulated radiation therapy commissioning recommendations of American Association of Physicists in Medicine Task Group 119, adapted to incorporate 3D data. Preliminary tests (“AP” and “3D-Bands”) were delivered to 9.5-cm usable diameter cylindrical PRESAGE dosimeters to validate the treatment planning systemmore » (TPS) for nonmodulated deliveries; assess the sensitivity, uniformity, and rotational symmetry of the PRESAGE dosimeters; and test the robustness of the remote dosimetry protocol. Following this, 4 clinical MRgIMRT plans (“MultiTarget,” “Prostate,” “Head/Neck,” and “C-Shape”) were measured using 13-cm usable diameter PRESAGE dosimeters. For all plans, 3D-γ (3% or 3 mm global, 10% threshold) passing rates were calculated and 3D-γ maps were examined. Point doses were measured with an IBA-CC01 ionization chamber for validation of absolute dose. Finally, by use of an in-house-developed, GPU-accelerated Monte Carlo algorithm (gPENELOPE), we independently calculated dose for all 6 Task Group 119 plans and compared against the TPS. Results: For PRESAGE measurements, 3D-γ analysis yielded passing rates of 98.7%, 99.2%, 98.5%, 98.0%, 99.2%, and 90.7% for AP, 3D-Bands, MultiTarget, Prostate, Head/Neck, and C-Shape, respectively. Ion chamber measurements were within an average of 0.5% (±1.1%) from the TPS dose. Monte Carlo calculations demonstrated good agreement with the TPS, with a mean 3D-γ passing rate of 98.5% ± 1.9% using a stricter 2%/2-mm criterion. Conclusions: We have validated the dosimetric accuracy of a commercial MRgIMRT system using high-resolution 3D techniques. We have demonstrated for the first time that hybrid 3D remote dosimetry is a comprehensive and feasible approach to commissioning MRgIMRT. This may provide better sensitivity in error detection compared with standard 2-dimensional measurements and could be used when implementing complex new magnetic resonance guided radiation therapy technologies.« less

Comparing the quality of passively-scattered proton and photon tomotherapy plans for brain and head and neck disease sites.

PubMed

Kainz, Kristofer; Firat, Selim; Wilson, J Frank; Schultz, Christopher; Siker, Malika; Wang, Andrew; Olson, Dan; Li, X Allen

2015-03-21

We compare the quality of photon IMRT (helical tomotherapy) with classic proton plans for brain, head and neck tumors, in terms of target dose uniformity and conformity along with organ-at-risk (OAR) sparing. Plans were created for twelve target volumes among eight cases. All patients were originally planned and treated using helical tomotherapy. Proton plans were generated using a passively-scattered beam model with a maximum range of 32 g cm(-2) (225 MeV), range modulation in 0.5 g cm(-2) increments and range compensators with 4.8 mm milling tool diameters. All proton plans were limited to two to four beams. Plan quality was compared using uniformity index (UI), conformation number (CN) and a EUD-based plan quality index (fEUD). For 11 of the 12 targets, UI was improved for the proton plan; on average, UI was 1.05 for protons versus 1.08 for tomotherapy. For 7 of the 12 targets, the tomotherapy plan exhibited more favorable CN. For proximal OARs, the improved dose conformity to the target volume from tomotherapy led to a lower maximum dose. For distal OARs, the maximum dose was much lower for proton plans. For 6 of the 8 cases, near-total avoidance for distal OARs provided by protons leads to improved fEUD. However, if distal OARs are excluded in the fEUD calculation, the proton plans exhibit better fEUD in only 3 of the 8 cases. The distal OAR sparing and target dose uniformity are generally better with passive-scatter proton planning than with photon tomotherapy; proton therapy may be preferred if the clinician deems those attributes critical. However, tomotherapy may serve equally as well as protons for cases where superior target dose conformity from tomotherapy leads to plan quality nearly identical to or better than protons and for cases where distal OAR sparing is not concerning.

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

Moteabbed, M; Depauw, N; Kooy, H

Purpose: To investigate the dosimetric benefits of pencil beam scanning (PBS) compared with passive scattered (PS) proton therapy for treatment of pediatric head&neck patients as a function of the PBS spot size and explore the advantages of using apertures in PBS. Methods: Ten pediatric patients with head&neck cancers treated by PS proton therapy at our institution were retrospectively selected. The histologies included rhabdomyosarcoma, ependymoma, astrocytoma, craniopharyngioma and germinoma. The prescribed dose ranged from 36 to 54 Gy(RBE). Five PBS plans were created for each patient using variable spot size (average sigma at isocenter) and choice of beam specific apertures: (1)more » 10mm spots, (2) 10mm spots with apertures, (3) 6mm spots, (4) 6mm spots with apertures, and (5) 3mm spots. The plans were optimized for intensity modulated proton therapy (IMPT) with no single beam uniformity constraints. Dose volume indices as well as equivalent uniform dose (EUD) were compared between PS and PBS plans. Results: Although target coverage was clinically adequate for all cases, the plans with largest (10mm) spots provide inferior quality compared with PS in terms of dose to organs-at-risk (OAR). However, adding apertures to these plans ensured lower OAR dose than PS. The average EUD difference between PBS and PS plans over all patients and organs at risk were (1) 2.5%, (2) −5.1%, (3) -5%, (4) −7.8%, and (5) −9.5%. As the spot size decreased, more conformal plans were achieved that offered similar target coverage but lower dose to the neighboring healthy organs, while alleviating the need for using apertures. Conclusion: The application of PBS does not always translate to better plan qualities compared to PS depending on the available beam spot size. We recommend that institutions with spot size larger than ∼6mm at isocenter consider using apertures to guarantee clinically comparable or superior dosimetric efficacy to PS treatments.« less

Industrial and biomedical use of aerospace personal cooling garments

NASA Technical Reports Server (NTRS)

Williams, B. A.; Mcewen, G. N., Jr.; Montgomery, L. D.; Elkins, W. E.

1975-01-01

Liquid-cooled garments (LCG) have been developed which utilize liquid-cooled modules rather than the network of tygon tubing typical of Apollo LCG's. The ultra-thin, heat-sealed, polyurethane modules are situated over the body to cover 50 percent of the body surface area with special emphasis on the 'working' muscles and the head-neck area. These garments are being designed specifically for industrial and biomedical uses, such as: a head-neck cooling system which is being tested for race-car drivers, tractor drivers, truck drivers, or a head-neck cooling system tested for the reduction of the scalp hair loss which normally accompanies cancer treatments. A combined head-neck and thorax unit is being developed for use during mine distaster rescue operations, and for other hazardous hot applications. Finally applications for head-neck and partitional cooling are anticipated for military pilots, tank drivers, and heavy equipment operations.

SU-F-BRB-12: A Novel Haar Wavelet Based Approach to Deliver Non-Coplanar Intensity Modulated Radiotherapy Using Sparse Orthogonal Collimators

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

Nguyen, D; Ruan, D; Low, D

2015-06-15

Purpose: Existing efforts to replace complex multileaf collimator (MLC) by simple jaws for intensity modulated radiation therapy (IMRT) resulted in unacceptable compromise in plan quality and delivery efficiency. We introduce a novel fluence map segmentation method based on compressed sensing for plan delivery using a simplified sparse orthogonal collimator (SOC) on the 4π non-coplanar radiotherapy platform. Methods: 4π plans with varying prescription doses were first created by automatically selecting and optimizing 20 non-coplanar beams for 2 GBM, 2 head & neck, and 2 lung patients. To create deliverable 4π plans using SOC, which are two pairs of orthogonal collimators withmore » 1 to 4 leaves in each collimator bank, a Haar Fluence Optimization (HFO) method was used to regulate the number of Haar wavelet coefficients while maximizing the dose fidelity to the ideal prescription. The plans were directly stratified utilizing the optimized Haar wavelet rectangular basis. A matching number of deliverable segments were stratified for the MLC-based plans. Results: Compared to the MLC-based 4π plans, the SOC-based 4π plans increased the average PTV dose homogeneity from 0.811 to 0.913. PTV D98 and D99 were improved by 3.53% and 5.60% of the corresponding prescription doses. The average mean and maximal OAR doses slightly increased by 0.57% and 2.57% of the prescription doses. The average number of segments ranged between 5 and 30 per beam. The collimator travel time to create the segments decreased with increasing leaf numbers in the SOC. The two and four leaf designs were 1.71 and 1.93 times more efficient, on average, than the single leaf design. Conclusion: The innovative dose domain optimization based on compressed sensing enables uncompromised 4π non-coplanar IMRT dose delivery using simple rectangular segments that are deliverable using a sparse orthogonal collimator, which only requires 8 to 16 leaves yet is unlimited in modulation resolution. This work is supported in part by Varian Medical Systems, Inc. and NIH R43 CA18339.« less

SU-F-J-13: Choosing An IMRT Technique in the Treatment of Head and Neck Cancer with Daily Localization Uncertainties

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

Lin, T; Wang, L; Galloway, T

Purpose: Head and Neck cancer treatment with IMRT/VMAT has two choices: split-filed IMRT(SFI), in which the LAN is treated with a separate anterior field and the extended whole-field IMRT(WFI) in which LAN is included with the IMRT/VMAT field. This study shows that under the same dose limit criteria, choosing the technique becomes a critical issue if daily localization and immobilization altered the dose distribution. Methods: Nine common head-and-neck cancer cases were chosen to illustrate how the daily localization and immobilization uncertainties affect to choose between SFI and WFI. Both SFI and WFI at upper target coverage were generated with VMAT.more » For each case, the same planning criteria were applied to the target and critical structures; therefore, similar target coverage and dose falloff can be observed in both techniques. Thirty days of kV cone beam CT(CBCT) images on each case were also delineated with contralateral and ipsilateral target as well as larynx as critical structure. About 300 CBCT images with daily delivered doses were analyzed and compared in a form of dose-volume histograms. Results: While both plans for SFI and WFI with VMAT planning utilized and meet the criteria of D95>prescription dose and for not-involved larynx with mean dose <35Gy and V55<10%, the daily localization and immobilization has a great contribution to the resulted dose delivery. With WFI, the better daily contralateral and ipsilateral neck target coverage can reflect a simpler or shorter localization; however, a much superior avoidance (WFI: mean dose a 42.5Gy; SFI: mean dose a 18.9Gy) of the non-involved larynx from the SFI is preferred. Conclusion: Dosimetrically, SFI and WFI are equally well for head and Neck cancer treatment with VMAT technique; however, if considering the contribution of daily localization(CBCT) method uncertainties, SFI is better with sparing non-involved larynx and WFI has better target coverage.« less

Exposure of the examiner to radiation during myelography versus radiculography and root block: A comparative study.

PubMed

Yamane, Kentaro; Kai, Nobuo; Miyamoto, Tadashi; Matsushita, Tomohiro

2017-03-01

Exposure to radiation over many years prompts concerns regarding potential health-related effects, particularly the incidence of cataracts and the development of cancer. The purpose of this study was to examine and compare the exposure of the examiner to radiation during myelography versus radiculography and root block. A total of 114 examinations were performed in our institute in the 6 months. Sixty-two examinations were performed during myelography in the first 3 months (MG group), while 52 were performed during radiculography and root block in the last 3 months (RB group). The examiner wore a torso protector, a neck protector, radiation protection gloves, and radiation protection glasses. Optically stimulated luminescence (OSL) dosimeter badges were placed on both the inside and the outside of each protector. The dosimeters were exchanged every month. Radiation doses (mSv) were measured as the integrated radiation quantity every month from the OSL dosimeters. The effective dose and the equivalent doses of hand, skin, and eyes were investigated. The mean equivalent doses were significantly lower outside the neck, torso, eye protectors, and inside the torso protector in the RB group than in the MG group. Conversely, the mean equivalent dose was significantly lower outside the hand protector in the MG group than in the RB group. The use of a neck protector significantly decreased the effective dose compared to the non-use of a neck protector in the RB group. The present study showed the standard radiation exposure to the examiner during myelography, radiculography, and root block. Receiving full protection including a neck protector and protection gloves is an easy and reliable means to reduce radiation exposure. Copyright © 2016 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.

Locoregional control after intensity-modulated radiotherapy for nasopharyngeal carcinoma with an anatomy-based target definition.

PubMed

Kawashima, Mitsuhiko; Ariji, Takaki; Kameoka, Satoru; Ueda, Takashi; Kohno, Ryosuke; Nishio, Teiji; Arahira, Satoko; Motegi, Atsushi; Zenda, Sadamoto; Akimoto, Tetsuo; Tahara, Makoto; Hayashi, Ryuichi

2013-12-01

The objective of the study was to evaluate locoregional control after intensity-modulated radiotherapy for nasopharyngeal cancer using a target definition along with anatomical boundaries. Forty patients with biopsy-proven squamous cell or non-keratinizing carcinoma of the nasopharynx who underwent intensity-modulated radiotherapy between April 2006 and November 2009 were reviewed. There were 10 females and 30 males with a median age of 48 years (range, 17-74 years). More than half of the patients had T3/4 (n = 21) and/or N2/3 (n = 24) disease. Intensity-modulated radiotherapy was administered as 70 Gy/33 fractions with or without concomitant chemotherapy. The clinical target volume was contoured along with muscular fascia or periosteum, and the prescribed radiotherapy dose was determined for each anatomical compartment and lymph node level in the head and neck. One local recurrence was observed at Meckel's cave on the periphery of the high-risk clinical target volume receiving a total dose of <63 Gy. Otherwise, six locoregional failures were observed within irradiated volume receiving 70 Gy. Local and nodal control rates at 3 years were 91 and 89%, respectively. Adverse events were acceptable, and 25 (81%) of 31 patients who were alive without recurrence at 2 years had xerostomia of ≤Grade 1. The overall survival rate at 3 years was 87%. Target definition along with anatomically defined boundaries was feasible without compromise of the therapeutic ratio. It is worth testing this method further to minimize the unnecessary irradiated volume and to standardize the target definition in intensity-modulated radiotherapy for nasopharyngeal cancer.

Three-dimensional radiotherapy of head and neck and esophageal carcinomas: a monoisocentric treatment technique to achieve improved dose distributions.

PubMed

Ahmad, M; Nath, R

2001-02-20

The specific aim of three-dimensional conformal radiotherapy is to deliver adequate therapeutic radiation dose to the target volume while concomitantly keeping the dose to surrounding and intervening normal tissues to a minimum. The objective of this study is to examine dose distributions produced by various radiotherapy techniques used in managing head and neck tumors when the upper part of the esophagus is also involved. Treatment planning was performed with a three-dimensional (3-D) treatment planning system. Computerized tomographic (CT) scans used by this system to generate isodose distributions and dose-volume histograms were obtained directly from the CT scanner, which is connected via ethernet cabling to the 3-D planning system. These are useful clinical tools for evaluating the dose distribution to the treatment volume, clinical target volume, gross tumor volume, and certain critical organs. Using 6 and 18 MV photon beams, different configurations of standard treatment techniques for head and neck and esophageal carcinoma were studied and the resulting dose distributions were analyzed. Film validation dosimetry in solid-water phantom was performed to assess the magnitude of dose inhomogeneity at the field junction. Real-time dose measurements on patients using diode dosimetry were made and compared with computed dose values. With regard to minimizing radiation dose to surrounding structures (i.e., lung, spinal cord, etc.), the monoisocentric technique gave the best isodose distributions in terms of dose uniformity. The mini-mantle anterior-posterior/posterior-anterior (AP/PA) technique produced grossly non-uniform dose distribution with excessive hot spots. The dose measured on the patient during the treatment agrees to within +/- 5 % with the computed dose. The protocols presented in this work for simulation, immobilization and treatment planning of patients with head and neck and esophageal tumors provide the optimum dose distributions in the target volume with reduced irradiation of surrounding non-target tissues, and can be routinely implemented in a radiation oncology department. The presence of a real-time dose-measuring system plays an important role in verifying the actual delivery of radiation dose.

Estimating thyroid dose in pediatric CT exams from surface dose measurement

NASA Astrophysics Data System (ADS)

Al-Senan, Rani; Mueller, Deborah L.; Hatab, Mustapha R.

2012-07-01

The purpose of this study was to investigate the possibility of estimating pediatric thyroid doses from CT using surface neck doses. Optically stimulated luminescence dosimeters were used to measure the neck surface dose of 25 children ranging in ages between one and three years old. The neck circumference for each child was measured. The relationship between obtained surface doses and thyroid dose was studied using acrylic phantoms of various sizes and with holes of different depths. The ratios of hole-to-surface doses were used to convert patients' surface dose to thyroid dose. ImPACT software was utilized to calculate thyroid dose after applying the appropriate age correction factors. A paired t-test was performed to compare thyroid doses from our approach and ImPACT. The ratio of thyroid to surface dose was found to be 1.1. Thyroid doses ranged from 20 to 80 mGy. Comparison showed no statistical significance (p = 0.18). In addition, the average of surface dose variation along the z-axis in helical scans was studied and found to range between 5% (in 10 cm diameter phantom/24 mm collimation/pitch 1.0) and 8% (in 16 cm diameter phantom/12 mm collimation/pitch 0.7). We conclude that surface dose is an acceptable predictor for pediatric thyroid dose from CT. The uncertainty due to surface dose variability may be reduced if narrower collimation is used with a pitch factor close to 1.0. Also, the results did not show any effect of thyroid depth on the measured dose.

SU-E-I-32: Benchmarking Head CT Doses: A Pooled Vs. Protocol Specific Analysis of Radiation Doses in Adult Head CT Examinations

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

Fujii, K; UCLA School of Medicine, Los Angeles, CA; Bostani, M

Purpose: The aim of this study was to collect CT dose index data from adult head exams to establish benchmarks based on either: (a) values pooled from all head exams or (b) values for specific protocols. One part of this was to investigate differences in scan frequency and CT dose index data for inpatients versus outpatients. Methods: We collected CT dose index data (CTDIvol) from adult head CT examinations performed at our medical facilities from Jan 1st to Dec 31th, 2014. Four of these scanners were used for inpatients, the other five were used for outpatients. All scanners used Tubemore » Current Modulation. We used X-ray dose management software to mine dose index data and evaluate CTDIvol for 15807 inpatients and 4263 outpatients undergoing Routine Brain, Sinus, Facial/Mandible, Temporal Bone, CTA Brain and CTA Brain-Neck protocols, and combined across all protocols. Results: For inpatients, Routine Brain series represented 84% of total scans performed. For outpatients, Sinus scans represented the largest fraction (36%). The CTDIvol (mean ± SD) across all head protocols was 39 ± 30 mGy (min-max: 3.3–540 mGy). The CTDIvol for Routine Brain was 51 ± 6.2 mGy (min-max: 36–84 mGy). The values for Sinus were 24 ± 3.2 mGy (min-max: 13–44 mGy) and for Facial/Mandible were 22 ± 4.3 mGy (min-max: 14–46 mGy). The mean CTDIvol for inpatients and outpatients was similar across protocols with one exception (CTA Brain-Neck). Conclusion: There is substantial dose variation when results from all protocols are pooled together; this is primarily a function of the differences in technical factors of the protocols themselves. When protocols are analyzed separately, there is much less variability. While analyzing pooled data affords some utility, reviewing protocols segregated by clinical indication provides greater opportunity for optimization and establishing useful benchmarks.« less

OCCUPATIONAL RADIATION DOSES TO OPERATORS PERFORMING FLUOROSCOPICALLY-GUIDED PROCEDURES

PubMed Central

Kim, Kwang Pyo; Miller, Donald L.; de Gonzalez, Amy Berrington; Balter, Stephen; Kleinerman, Ruth A.; Ostroumova, Evgenia; Simon, Steven L.; Linet, Martha S.

2012-01-01

In the past 30 years, the numbers and types of fluoroscopically-guided (FG) procedures have increased dramatically. The objective of the present study is to provide estimated radiation doses to physician specialists, other than cardiologists, who perform FG procedures. We searched Medline to identify English-language journal articles reporting radiation exposures to these physicians. We then identified several primarily therapeutic FG procedures that met specific criteria: well-defined procedures for which there were at least five published reports of estimated radiation doses to the operator, procedures performed frequently in current medical practice, and inclusion of physicians from multiple medical specialties. These procedures were percutaneous nephrolithotomy (PCNL), vertebroplasty, orthopedic extremity nailing for treatment of fractures, biliary tract procedures, transjugular intrahepatic portosystemic shunt creation (TIPS), head/neck endovascular therapeutic procedures, and endoscopic retrograde cholangiopancreatography (ERCP). We abstracted radiation doses and other associated data, and estimated effective dose to operators. Operators received estimated doses per patient procedure equivalent to doses received by interventional cardiologists. The estimated effective dose per case ranged from 1.7 – 56μSv for PCNL, 0.1 – 101 μSv for vertebroplasty, 2.5 – 88μSv for orthopedic extremity nailing, 2.0 – 46μSv for biliary tract procedures, 2.5 – 74μSv for TIPS, 1.8 – 53μSv for head/neck endovascular therapeutic procedures, and 0.2 – 49μSv for ERCP. Overall, mean operator radiation dose per case measured over personal protective devices at different anatomic sites on the head and body ranged from 19 – 800 (median = 113) μSv at eye level, 6 – 1180 (median = 75)μSv at the neck, and 2 – 1600 (median = 302) μSv at the trunk. Operators’ hands often received greater doses than the eyes, neck or trunk. Large variations in operator doses suggest that optimizing procedure protocols and proper use of protective devices and shields might reduce occupational radiation dose substantially. PMID:22647920

Reirradiation for second primary or recurrent cancers of the head and neck: Dosimetric and outcome analysis.

PubMed

Garg, Shivank; Kilburn, Jeremy M; Lucas, John T; Randolph, David; Urbanic, James J; Hinson, William H; Kearns, William T; Porosnicu, Mercedes; Greven, Kathryn

2016-04-01

The purpose of this study was to examine outcomes, toxicity, and dosimetric characteristics of patients treated with reirradiation for head and neck cancers. Fifty patients underwent ≥2 courses of radiation therapy (RT) postoperatively or definitively with or without chemotherapy. Composite dose volume histograms (DVHs) for selected anatomic structures were correlated with grade ≥3 late toxicity. Median initial and retreatment radiation dose was 64 and 60 Gy, respectively. Median overall survival (OS), progression-free survival (PFS), and 1-year PFS rates were 18 months, 11 months, and 45%, respectively, with 13 months median follow-up. Thirty-four percent of patients experienced grade ≥3 late toxicity with 1 death from carotid blowout. The DVH corresponding to the carotid blowout fell above the third quartile compared with other patients. Our analysis is the first to systematically evaluate the dose to the carotid artery using composite dosimetry in head and neck reirradiation patients, and demonstrates a promising technique for evaluating the dose to other normal tissue structures. © 2015 Wiley Periodicals, Inc. Head Neck 38: E961-E969, 2016. © 2015 Wiley Periodicals, Inc.

Quality of Intensity Modulated Radiation Therapy Treatment Plans Using a ⁶⁰Co Magnetic Resonance Image Guidance Radiation Therapy System.

PubMed

Wooten, H Omar; Green, Olga; Yang, Min; DeWees, Todd; Kashani, Rojano; Olsen, Jeff; Michalski, Jeff; Yang, Deshan; Tanderup, Kari; Hu, Yanle; Li, H Harold; Mutic, Sasa

2015-07-15

This work describes a commercial treatment planning system, its technical features, and its capabilities for creating (60)Co intensity modulated radiation therapy (IMRT) treatment plans for a magnetic resonance image guidance radiation therapy (MR-IGRT) system. The ViewRay treatment planning system (Oakwood Village, OH) was used to create (60)Co IMRT treatment plans for 33 cancer patients with disease in the abdominal, pelvic, thorax, and head and neck regions using physician-specified patient-specific target coverage and organ at risk (OAR) objectives. Backup plans using a third-party linear accelerator (linac)-based planning system were also created. Plans were evaluated by attending physicians and approved for treatment. The (60)Co and linac plans were compared by evaluating conformity numbers (CN) with 100% and 95% of prescription reference doses and heterogeneity indices (HI) for planning target volumes (PTVs) and maximum, mean, and dose-volume histogram (DVH) values for OARs. All (60)Co IMRT plans achieved PTV coverage and OAR sparing that were similar to linac plans. PTV conformity for (60)Co was within <1% and 3% of linac plans for 100% and 95% prescription reference isodoses, respectively, and heterogeneity was on average 4% greater. Comparisons of OAR mean dose showed generally better sparing with linac plans in the low-dose range <20 Gy, but comparable sparing for organs with mean doses >20 Gy. The mean doses for all (60)Co plan OARs were within clinical tolerances. A commercial (60)Co MR-IGRT device can produce highly conformal IMRT treatment plans similar in quality to linac IMRT for a variety of disease sites. Additional work is in progress to evaluate the clinical benefit of other novel features of this MR-IGRT system. Copyright © 2015 Elsevier Inc. All rights reserved.

Electromyographic Control of a Hands-Free Electrolarynx Using Neck Strap Muscles

ERIC Educational Resources Information Center

Kubert, Heather L.; Stepp, Cara E.; Zeitels, Steven M.; Gooey, John E.; Walsh, Michael J.; Prakash, S. R.; Hillman, Robert E.; Heaton, James T.

2009-01-01

Three individuals with total laryngectomy were studied for their ability to control a hands-free electrolarynx (EL) using neck surface electromyography (EMG) for on/off and pitch modulation. The laryngectomy surgery of participants was modified to preserve neck strap musculature for EMG-based EL control (EMG-EL), with muscles on one side…

Dose to the Bladder Neck Is the Most Important Predictor for Acute and Late Toxicity After Low-Dose-Rate Prostate Brachytherapy: Implications for Establishing New Dose Constraints for Treatment Planning

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

Hathout, Lara; Folkert, Michael R.; Kollmeier, Marisa A.

2014-10-01

Purpose: To identify an anatomic structure predictive for acute (AUT) and late (LUT) urinary toxicity in patients with prostate cancer treated with low-dose-rate brachytherapy (LDR) with or without external beam radiation therapy (EBRT). Methods and Materials: From July 2002 to January 2013, 927 patients with prostate cancer (median age, 66 years) underwent LDR brachytherapy with Iodine 125 (n=753) or Palladium 103 (n=174) as definitive treatment (n=478) and as a boost (n=449) followed by supplemental EBRT (median dose, 50.4 Gy). Structures contoured on the computed tomographic (CT) scan on day 0 after implantation included prostate, urethra, bladder, and the bladder neck, defined asmore » 5 mm around the urethra between the catheter balloon and the prostatic urethra. AUT and LUT were assessed with the Common Terminology Criteria for Adverse Events, version4. Clinical and dosimetric factors associated with AUT and LUT were analyzed with Cox regression and receiver operating characteristic analysis to calculate area under the receiver operator curve (ROC) (AUC). Results: Grade ≥2 AUT and grade ≥2 LUT occurred in 520 patients (56%) and 154 patients (20%), respectively. No grade 4 toxicities were observed. Bladder neck D2cc retained a significant association with AUT (hazard ratio [HR], 1.03; 95% confidence interval [CI], 1.03-1.04; P<.0001) and LUT (HR, 1.01; 95% CI, 1.00-1.03; P=.014) on multivariable analysis. In a comparison of bladder neck with the standard dosimetric variables by use of ROC analysis (prostate V100 >90%, D90 >100%, V150 >60%, urethra D20 >130%), bladder neck D2cc >50% was shown to have the strongest prognostic power for AUT (AUC, 0.697; P<.0001) and LUT (AUC, 0.620; P<.001). Conclusions: Bladder neck D2cc >50% was the strongest predictor for grade ≥2 AUT and LUT in patients treated with LDR brachytherapy. These data support inclusion of bladder neck constraints into brachytherapy planning to decrease urinary toxicity.« less

MO-AB-BRA-01: A Global Level Set Based Formulation for Volumetric Modulated Arc Therapy

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

Nguyen, D; Lyu, Q; Ruan, D

2016-06-15

Purpose: The current clinical Volumetric Modulated Arc Therapy (VMAT) optimization is formulated as a non-convex problem and various greedy heuristics have been employed for an empirical solution, jeopardizing plan consistency and quality. We introduce a novel global direct aperture optimization method for VMAT to overcome these limitations. Methods: The global VMAT (gVMAT) planning was formulated as an optimization problem with an L2-norm fidelity term and an anisotropic total variation term. A level set function was used to describe the aperture shapes and adjacent aperture shapes were penalized to control MLC motion range. An alternating optimization strategy was implemented to solvemore » the fluence intensity and aperture shapes simultaneously. Single arc gVMAT plans, utilizing 180 beams with 2° angular resolution, were generated for a glioblastoma multiforme (GBM), lung (LNG), and 2 head and neck cases—one with 3 PTVs (H&N3PTV) and one with 4 PTVs (H&N4PTV). The plans were compared against the clinical VMAT (cVMAT) plans utilizing two overlapping coplanar arcs. Results: The optimization of the gVMAT plans had converged within 600 iterations. gVMAT reduced the average max and mean OAR dose by 6.59% and 7.45% of the prescription dose. Reductions in max dose and mean dose were as high as 14.5 Gy in the LNG case and 15.3 Gy in the H&N3PTV case. PTV coverages (D95, D98, D99) were within 0.25% of the prescription dose. By globally considering all beams, the gVMAT optimizer allowed some beams to deliver higher intensities, yielding a dose distribution that resembles a static beam IMRT plan with beam orientation optimization. Conclusions: The novel VMAT approach allows for the search of an optimal plan in the global solution space and generates deliverable apertures directly. The single arc VMAT approach fully utilizes the digital linacs’ capability in dose rate and gantry rotation speed modulation. Varian Medical Systems, NIH grant R01CA188300, NIH grant R43CA183390.« less

Determination of cytokine protein levels in oral secretions in patients undergoing radiotherapy for head and neck malignancies

PubMed Central

2012-01-01

Background Cytokines may be elevated in tumor and normal tissues following irradiation. Cytokine expression in these tissues may predict for toxicity or tumor control. The purpose of this pilot study was to determine the feasibility of measuring local salivary cytokine levels using buccal sponges in patients receiving chemo-radiation for head and neck malignancies. Patients and methods 11 patients with epithelial malignancies of the head and neck were recruiting to this study. All patients received radiotherapy to the head and neck region with doses ranging between 60 – 67.5 Gy. Chemotherapy was delivered concurrently with radiation in all patients. Salivary samples were obtained from high dose and low dose regions prior to treatment and at three intervals during treatment for assessment of cytokine levels (IL-4, IL-6, IL-8, IL-10, EGF, MCP-1, TNF-α, and VEGF). Results Cytokine levels were detectable in the salivary samples. Salivary cytokine levels of IL-4, IL-6, IL-8, EGF, MCP-1, TNF- α , and VEGF were higher in the high dose region compared to the low dose region at all time points (p < 0.05). A trend toward an increase in cytokine levels as radiation dose increased was observed for IL-6, IL-8, MCP-1, and TNF-α. Conclusion Assessment of salivary cytokine levels may provide a novel method to follow local cytokine levels during radiotherapy and may provide a mechanism to study cytokine levels in a regional manner. PMID:22537315

Reirradiation for recurrent head and neck cancers using charged particle or photon radiotherapy.

PubMed

Yamazaki, Hideya; Demizu, Yusuke; Okimoto, Tomoaki; Ogita, Mikio; Himei, Kengo; Nakamura, Satoaki; Suzuki, Gen; Yoshida, Ken; Kotsuma, Tadayuki; Yoshioka, Yasuo; Oh, Ryoongjin

2017-07-01

To examine the outcomes of reirradiation for recurrent head and neck cancers using different modalities. This retrospective study included 26 patients who received charged particle radiotherapy (CP) and 150 who received photon radiotherapy (117 CyberKnife radiotherapy [CK] and 36 intensity-modulated radiotherapy [IMRT]). Inverse probability of treatment weighting (IPTW) involving propensity scores was used to reduce background selection bias. Higher prescribed doses were used in CP than photon radiotherapy. The 1‑year overall survival (OS) rates were 67.9% for CP and 54.1% for photon radiotherapy (p = 0.15; 55% for CK and 51% for IMRT). In multivariate Cox regression, the significant prognostic factors for better survival were nasopharyngeal cancer, higher prescribed dose, and lower tumor volume. IPTW showed a statistically significant difference between CP and photon radiotherapy (p = 0.04). The local control rates for patients treated with CP and photon radiotherapy at 1 year were 66.9% (range 46.3-87.5%) and 67.1% (range 58.3-75.9%), respectively. A total of 48 patients (27%) experienced toxicity grade ≥3 (24% in the photon radiotherapy group and 46% in the CP group), including 17 patients with grade 5 toxicity. Multivariate analysis revealed that younger age and a larger planning target volume (PTV) were significant risk factors for grade 3 or worse toxicity. CP provided superior survival outcome compared to photon radiotherapy. Tumor volume, primary site (nasopharyngeal), and prescribed dose were identified as survival factors. Younger patients with a larger PTV experienced toxicity grade ≥3.

SU-F-T-224: Importance of Timely Review of Daily Cone-Beam CTs: Dosimetric Evaluation of Rejected CBCTs for Head and Neck Patients

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

Andrews, M; Yu, N; Joshi, N

Purpose: To dosimetrically evaluate the importance of timely reviewing daily CBCTs for patients with head and neck cancer. Methods: After each fraction daily cone-beam CT (CBCT) for head and neck patients are reviewed by physicians prior to next treatment. Physician rejected image registrations of CBCT were identified and analyzed for 17 patients. These CBCT images were rigidly fused with planning CT images and the contours from the planning CT were transferred to CBCTs. Because of limited extension in the superior-inferior dimension contours with partial volumes in CBCTs were discarded. The treatment isocenter was placed by applying the clinically recorded shiftsmore » to the volume isocenter of the CBCT. Dose was recalculated at the shifted isocenter using a homogeneous dose calculation algorithm. Dosimetrically relevant changes defined as greater than 5% deviation from the clinically accepted plans but with homogeneous dose calculation were evaluated for the high dose (HD), intermediate dose (ID), and low dose (LD) CTVs, spinal cord, larynx, oropharynx, parotids, and submandibular glands. Results: Among seventeen rejected CBCTS, HD-CTVs, ID-CTVs, and LD-CTVs were completely included in the CBCTs for 17, 1, and 15 patients, respectively. The prescription doses to the HD-CTV, ID-CTV, and LD-CTV were received by < 95% of the CTV volumes in 5/17, 1/1, and 5/15 patients respectively. For the spinal cord, the maximum doses (D0.03cc) were increased > 5% in 13 of 17 patients. For the oropharynx, larynx, parotid, and submandibular glands, the mean dose of these organs at risk was increased > 5% in 7/17, 8/12, 11/16 and 6/16 patients, respectively. Conclusion: Timely review daily CBCTs for head and neck patients under daily CBCT guidance is important, and uncorrected setup errors can translate to dosimetrically relevant dose increases in organsat- risk and dose decreases in the clinical target volumes.« less

Head and neck tumors after energetic proton irradiation in rats

NASA Astrophysics Data System (ADS)

Wood, D.; Cox, A.; Hardy, K.; Salmon, Y.; Trotter, R.

1994-10-01

This is a two-year progress report on a life span dose-response study of brain tumor risk at moderate to high doses of energetic protons. It was initiated because a joint NASA/USAF life span study of rhesus monkeys that were irradiated with 55-MeV protons (average surface dose, 3.5 Gy) indicated that the incidence of brain tumors per unit surface absorbed dose was over 19 times that of the human tinea capitis patients whose heads were exposed to 100 kv x-rays. Examination of those rats that died in the two-year interval after irradiation of the head revealed a linear dose-response for total head and neck tumor incidence in the dose range of 0-8.5 Gy. The exposed rats had a greater incidence of pituitary chromophobe adenomas, epithelial and mesothelial cell tumors than the unexposed controls but the excessive occurrence of malignant gliomas that was observed in the monkeys was absent in the rats. The estimated dose required to double the number of all types of head and neck tumors was 5.2 Gy. The highest dose, 18 Gy, resulted in high mortality due to obstructive squamous metaplasia at less than 50 weeks, prompting a new study of the relative bological effectiveness of high energy protons in producing this lesion.

An update on radiation therapy in head and neck cancers.

PubMed

Mazzola, Rosario; Fiorentino, Alba; Ricchetti, Francesco; Gregucci, Fabiana; Corradini, Stefanie; Alongi, Filippo

2018-04-01

Technological and technical improvements allowed for significant advances in the field of radiation therapy (RT) of head and neck cancer (HNC). Several organ-sparing strategies have been investigated with the objective to decrease acute and long-term adverse effects and, subsequently, to assure a better quality of life in patients affected by HNC. In this context, intensity modulated irradiation and the use of multimodality-imaging could help clinicians to obtain a rapid dose fall off towards surrounding healthy tissues and a better delineation of targets volumes and organs at risk. Areas covered: A literature review was performed with the aim to offer an update on radiation therapy in HNC. Expert commentary: During these last years, radiation oncologists have observed a continuous changing regarding radiation treatment for HNC. The adoption of intensity-modulated RT (IMRT) and the use of multimodality-imaging for tumor volume definition and organs at risk or delineation have improved the clinical outcomes of HNC patients. In the future, a better integration of functional imaging for target volume delineation as well as adaptive delivery strategies will allow to further personalize radiation oncology in HNC. Furthermore, the latest breakthrough technologies, such as magnetic resonance imaging (MRI)-linacs and heavy particles technologies have a great potential to improve treatment-related quality of life in HNC. Future studies are needed to demonstrate the clinical advantages of these new RT technologies in HNC.

Rational use of intensity-modulated radiation therapy: the importance of clinical outcome.

PubMed

De Neve, Wilfried; De Gersem, Werner; Madani, Indira

2012-01-01

During the last 2 decades, intensity-modulated radiation therapy (IMRT) became a standard technique despite its drawbacks of volume delineation, planning, robustness of delivery, challenging quality assurance, and cost as compared with non-IMRT. The theoretic advantages of IMRT dose distributions are generally accepted, but the clinical advantages remain debatable because of the lack of clinical assessment of the effort that is required to overshadow the disadvantages. Rational IMRT use requires a positive advantage/drawback balance. Only 5 randomized clinical trials (RCTs), 3 in the breast and 2 in the head and neck, which compare IMRT with non-IMRT (2-dimensional technique in four fifths of the trials), have been published (as of March 2011), and all had toxicity as the primary endpoint. More than 50 clinical trials compared results of IMRT-treated patients with a non-IMRT group, mostly historical controls. RCTs systematically showed a lower toxicity in IMRT-treated patients, and the non-RCTs confirmed these findings. Toxicity reduction, counterbalancing the drawbacks of IMRT, was convincing for breast and head and neck IMRT. For other tumor sites, the arguments favoring IMRT are weaker because of the inability to control bias outside the randomized setting. For anticancer efficacy endpoints, like survival, disease-specific survival, or locoregional control, the balance between advantages and drawbacks is fraught with uncertainties because of the absence of robust clinical data. Copyright © 2012 Elsevier Inc. All rights reserved.

A study to establish reasonable action limits for patient-specific quality assurance in intensity-modulated radiation therapy.

PubMed

Both, Stefan; Alecu, Ionut M; Stan, Andrada R; Alecu, Marius; Ciura, Andrei; Hansen, Jeremy M; Alecu, Rodica

2007-03-07

An effective patient quality assurance (QA) program for intensity-modulated radiation therapy (IMRT) requires accurate and realistic plan acceptance criteria--that is, action limits. Based on dose measurements performed with a commercially available two-dimensional (2D) diode array, we analyzed 747 fluence maps resulting from a routine patient QA program for IMRT plans. The fluence maps were calculated by three different commercially available (ADAC, CMS, Eclipse) treatment planning systems (TPSs) and were delivered using 6-MV X-ray beams produced by linear accelerators. To establish reasonably achievable and clinically acceptable limits for the dose deviations, the agreement between the measured and calculated fluence maps was evaluated in terms of percent dose error (PDE) for a few points and percent of passing points (PPP) for the isodose distribution. The analysis was conducted for each TPS used in the study (365 ADAC, 162 CMS,220 Eclipse), for multiple treatment sites (prostate, pelvis, head and neck, spine, rectum, anus, lung, brain), at the normalization point for 3% percentage difference (%Diff) and 3-mm distance to agreement (DTA) criteria. We investigated the treatment-site dependency of PPP and PDE. The results show that, at 3% and 3-mm criteria, a 95% PPP and 3% PDE can be achieved for prostate treatments and a 90% PPP and 5% PDE are attainable for any treatment site.

Assessment of olfactory threshold in patients undergoing radiotherapy for head and neck malignancies.

PubMed

Jalali, Mir Mohammad; Gerami, Hooshang; Rahimi, Abbas; Jafari, Manizheh

2014-10-01

Radiotherapy is a common treatment modality for patients with head and neck malignancies. As the nose lies within the field of radiotherapy of the head and neck, the olfactory fibers and olfactory receptors may be affected by radiation. The aim of this study was to evaluate changes in olfactory threshold in patients with head and neck malignancies who have received radiation to the head and neck. The olfactory threshold of patients with head and neck malignancies was assessed prospectively before radiation therapy and serially for up to 6 months after radiotherapy using sniff bottles. In vivo dosimetry was performed using 82 LiF (MCP) chips and a thermoluminescent dosimeter (TLD) system. Sixty-one patients were recruited before radiotherapy was commenced. Seven patients did not return for evaluation after radiation. Fifty-four patients were available for follow-up assessment (28 women, 26 men; age, 22-86 years; median, 49 years). Total radiation dose was 50.1 Gy (range, 30-66 Gy). Mean olfactory threshold scores were found to deteriorate significantly at various timepoints after radiotherapy (11.7 before radiotherapy versus 4.0 at Month 6, general linear model, P<0.0001). With in vivo dosimetry, we found that the median measured dose to the olfactory area was 334 µC. We also identified a cutoff point according to the dose to the olfactory epithelium. Olfactory threshold was significantly decreased 2-6 weeks after initiation of therapy, with cumulative local radiation >135 µC (Mann-Whitney U test, P=0.01). Deterioration in olfactory threshold scores was found at 6 months after initiation of radiation therapy. Provided that these results are reproducible, an evaluation of olfactory functioning in patients with head and neck malignancies using in vivo dosimetry may be useful for determining the optimal dose for patients treated with conformal radiotherapy techniques while avoiding the side effects of radiation.

The dilemma of parotid gland and pharyngeal constrictor muscles preservation—Is daily online image guidance required? A dosimetric analysis

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

Duffy, Olivia; Forde, Elizabeth; Leech, Michelle, E-mail: leechm@tcd.ie

With margin reduction common in head and neck radiotherapy, it is critical that the dosimetric effects of setup deviations are quantified. With past studies focusing on the quantification of positional and volumetric changes of organs at risk (OARs), this study aimed to measure the dose delivered to these the parotid gland (PG) and pharyngeal constrictor muscles (PCMs) using cone beam computed tomography (CBCT). Furthermore, this investigation sought to establish a potential time trend of change in dose delivered to target volumes secondary to ascertaining the need for daily image guidance (IG) to reduce the dose burden to these important OARs.more » Intensity modulated radiotherapy (IMRT) plans for 5 locally advanced head and neck patients' plans were created and mapped to weekly CBCTs. Each plan was recalculated without heterogeneity correction allowing for dosimetric comparison. Dosimetric endpoints recorded to assess the effect of positional variation were as per ICRU 83 and included D{sub 95} and D{sub 98} for the target volumes, mean dose (MD) and V{sub 30} {sub Gy} for the PGs, and V{sub 50} {sub Gy} and MD for the PCMs. Results were deemed statistically significant if p < 0.05. No significant time trends were established for these OARs. A significant decrease in V{sub 50} {sub Gy} was observed for all PCMs (p < 0.001) on all CBCTs relative to the original plan. Regarding target volumes, a highly significant decrease in MD (MD = 20 Gy, CI: −20.310 to −19.820) in D{sub 98} of the high-dose planning target volume (PTV [70 Gy]; PTVD{sub 98%} = 70 Gy) for case 3 was found (p ≤ 0.001). A nonpredictable, yet significant dosimetric effect was found. A clinically acceptable balance must be achieved between OAR dosimetry and target coverage as can be achieved by frequent IG.« less

A methodology to investigate the impact of image distortions on the radiation dose when using magnetic resonance images for planning

NASA Astrophysics Data System (ADS)

Yan, Yue; Yang, Jinzhong; Beddar, Sam; Ibbott, Geoffrey; Wen, Zhifei; Court, Laurence E.; Hwang, Ken-Pin; Kadbi, Mo; Krishnan, Sunil; Fuller, Clifton D.; Frank, Steven J.; Yang, James; Balter, Peter; Kudchadker, Rajat J.; Wang, Jihong

2018-04-01

We developed a novel technique to study the impact of geometric distortion of magnetic resonance imaging (MRI) on intensity-modulated radiation therapy treatment planning. The measured 3D datasets of residual geometric distortion (a 1.5 T MRI component of an MRI linear accelerator system) was fitted with a second-order polynomial model to map the spatial dependence of geometric distortions. Then the geometric distortion model was applied to computed tomography (CT) image and structure data to simulate the distortion of MRI data and structures. Fourteen CT-based treatment plans were selected from patients treated for gastrointestinal, genitourinary, thoracic, head and neck, or spinal tumors. Plans based on the distorted CT and structure data were generated (as the distorted plans). Dose deviations of the distorted plans were calculated and compared with the original plans to study the dosimetric impact of MRI distortion. The MRI geometric distortion led to notable dose deviations in five of the 14 patients, causing loss of target coverage of up to 3.68% and dose deviations to organs at risk in three patients, increasing the mean dose to the chest wall by up to 6.19 Gy in a gastrointestinal patient, and increases the maximum dose to the lung by 5.17 Gy in a thoracic patient.

Smooth Pursuit Eye Movement Deficits in Patients With Whiplash and Neck Pain are Modulated by Target Predictability.

PubMed

Janssen, Malou; Ischebeck, Britta K; de Vries, Jurryt; Kleinrensink, Gert-Jan; Frens, Maarten A; van der Geest, Jos N

2015-10-01

This is a cross-sectional study. The purpose of this study is to support and extend previous observations on oculomotor disturbances in patients with neck pain and whiplash-associated disorders (WADs) by systematically investigating the effect of static neck torsion on smooth pursuit in response to both predictably and unpredictably moving targets using video-oculography. Previous studies showed that in patients with neck complaints, for instance due to WAD, extreme static neck torsion deteriorates smooth pursuit eye movements in response to predictably moving targets compared with healthy controls. Eye movements in response to a smoothly moving target were recorded with video-oculography in a heterogeneous group of 55 patients with neck pain (including 11 patients with WAD) and 20 healthy controls. Smooth pursuit performance was determined while the trunk was fixed in 7 static rotations relative to the head (from 45° to the left to 45° to right), using both predictably and unpredictably moving stimuli. Patients had reduced smooth pursuit gains and smooth pursuit gain decreased due to neck torsion. Healthy controls showed higher gains for predictably moving targets compared with unpredictably moving targets, whereas patients with neck pain had similar gains in response to both types of target movements. In 11 patients with WAD, increased neck torsion decreased smooth pursuit performance, but only for predictably moving targets. Smooth pursuit of patients with neck pain is affected. The previously reported WAD-specific decline in smooth pursuit due to increased neck torsion seems to be modulated by the predictability of the movement of the target. The observed oculomotor disturbances in patients with WAD are therefore unlikely to be induced by impaired neck proprioception alone. 3.

Four-dimensional multislice computed tomography for determination of respiratory lung tumor motion in conformal radiotherapy

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

Leter, Edward M.; Cademartiri, Filippo; Levendag, Peter C.

2005-07-01

Purpose: We used four-dimensional multislice spiral computed tomography (MSCT) to determine respiratory lung-tumor motion and compared this strategy to common clinical practice in conformal radiotherapy treatment-planning imaging. Methods and Materials: The entire lung volume of 10 consecutive patients with 14 lung metastases were scanned by a 16-slice MSCT. During the scans, patients were instructed to breathe through a spirometer that was connected to a laptop computer. For each patient, 10 stacks of 1.5-mm slices, equally distributed throughout the respiratory cycle, were reconstructed from the acquired MSCT data. The lung tumors were manually contoured in each data set. For each patient,more » the tumor-volume contours of all data sets were copied to 1 data set, which allowed determination of the volume that encompassed all 10 lung-tumor positions (i.e., the tumor-traversed volume [TTV]) during the respiratory cycle. The TTV was compared with the 10 tumor volumes contoured for each patient, to which an empiric respiratory-motion margin was added. The latter target volumes were designated internal-motion included tumor volume (IMITV). Results: The TTV measurements were significantly smaller than the reference IMITV measurements (5.2 {+-} 10.2 cm{sup 3} and 10.1 {+-} 13.7 cm{sup 3}, respectively). All 10 IMITVs for 2 of the 4 tumors in 1 subject completely encompassed the TTV. All 10 IMITVs for 3 tumors in 2 patients did not show overlap with up to 35% of the corresponding TTV. The 10 IMITVs for the remaining tumors either completely encompassed the corresponding TTV or did not show overlap with up to 26% of the corresponding TTV. Conclusions: We found that individualized determination of respiratory lung-tumor motion by four-dimensional respiratory-gated MSCT represents a better and simple strategy to incorporate periodic physiologic motion compared with a generalized approach. The former strategy can, therefore, improve common and state-of-the-art clinical practice in conformal radiotherapy.« less

SU-F-T-195: Systematic Constraining of Contralateral Parotid Gland Led to Improved Dosimetric Outcomes for Multi-Field Optimization with Scanning Beam Proton Therapy: Promising Results From a Pilot Study in Patients with Base of Tongue Carcinoma

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

Wu, R; Liu, A; Poenisch, F

Purpose: Treatment planning for Intensity Modulated Proton Therapy (IMPT) for head and neck cancer is time-consuming due to the large number of organs-at-risk (OAR) to be considered. As there are many competing objectives and also wide range of acceptable OAR constraints, the final approved plan may not be most optimal for the given structures. We evaluated the dose reduction to the contralateral parotid by implementing standardized constraints during optimization for scanning beam proton therapy planning. Methods: Twenty-four (24) consecutive patients previously treated for base of tongue carcinoma were retrospectively selected. The doses were 70Gy, 63Gy and 57Gy (SIB in 33more » fractions) for high-, intermediate-, and standard-risk clinical target volumes (CTV), respectively; the treatment included bilateral neck. Scanning beams using MFO with standardized bilateral anterior oblique and PA fields were applied. New plans where then developed and optimized by employing additional contralateral parotid constraints at multiple defined dose levels. Using a step-wise iterative process, the volume-based constraints at each level were then further reduced until known target coverages were compromised. The newly developed plans were then compared to the original clinically approved plans using paired student t-testing. Results: All 24 newly optimized treatment plans maintained initial plan quality as compared to the approved plans, and the 98% prescription dose coverage to the CTV’s were not compromised. Representative DVH comparison is shown in FIGURE 1. The contralateral parotid doses were reduced at all levels of interest when systematic constraints were applied to V10, V20, V30 and V40Gy (All P<0.0001; TABLE 1). Overall, the mean contralateral parotid doses were reduced by 2.26 Gy on average, a ∼13% relative improvement. Conclusion: Applying systematic and volume-based contralateral parotid constraints for IMPT planning significantly reduced the dose at all dosimetric levels for patients with base of tongue cancer.« 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

Independent dose verification system with Monte Carlo simulations using TOPAS for passive scattering proton therapy at the National Cancer Center in Korea

NASA Astrophysics Data System (ADS)

Shin, Wook-Geun; Testa, Mauro; Kim, Hak Soo; Jeong, Jong Hwi; Byeong Lee, Se; Kim, Yeon-Joo; Min, Chul Hee

2017-10-01

For the independent validation of treatment plans, we developed a fully automated Monte Carlo (MC)-based patient dose calculation system with the tool for particle simulation (TOPAS) and proton therapy machine installed at the National Cancer Center in Korea to enable routine and automatic dose recalculation for each patient. The proton beam nozzle was modeled with TOPAS to simulate the therapeutic beam, and MC commissioning was performed by comparing percent depth dose with the measurement. The beam set-up based on the prescribed beam range and modulation width was automated by modifying the vendor-specific method. The CT phantom was modeled based on the DICOM CT files with TOPAS-built-in function, and an in-house-developed C++ code directly imports the CT files for positioning the CT phantom, RT-plan file for simulating the treatment plan, and RT-structure file for applying the Hounsfield unit (HU) assignment, respectively. The developed system was validated by comparing the dose distributions with those calculated by the treatment planning system (TPS) for a lung phantom and two patient cases of abdomen and internal mammary node. The results of the beam commissioning were in good agreement of up to 0.8 mm2 g-1 for B8 option in both of the beam range and the modulation width of the spread-out Bragg peaks. The beam set-up technique can predict the range and modulation width with an accuracy of 0.06% and 0.51%, respectively, with respect to the prescribed range and modulation in arbitrary points of B5 option (128.3, 132.0, and 141.2 mm2 g-1 of range). The dose distributions showed higher than 99% passing rate for the 3D gamma index (3 mm distance to agreement and 3% dose difference) between the MC simulations and the clinical TPS in the target volume. However, in the normal tissues, less favorable agreements were obtained for the radiation treatment planning with the lung phantom and internal mammary node cases. The discrepancies might come from the limitations of the clinical TPS, which is the inaccurate dose calculation algorithm for the scattering effect, in the range compensator and inhomogeneous material. Moreover, the steep slope of the compensator, conversion of the HU values to the human phantom, and the dose calculation algorithm for the HU assignment also could be reasons of the discrepancies. The current study could be used for the independent dose validation of treatment plans including high inhomogeneities, the steep compensator, and riskiness such as lung, head & neck cases. According to the treatment policy, the dose discrepancies predicted with MC could be used for the acceptance decision of the original treatment plan.

Conebeam CT of the head and neck, part 1: physical principles.

PubMed

Miracle, A C; Mukherji, S K

2009-06-01

Conebeam x-ray CT (CBCT) is a developing imaging technique designed to provide relatively low-dose high-spatial-resolution visualization of high-contrast structures in the head and neck and other anatomic areas. This first installment in a 2-part review will address the physical principles underlying CBCT imaging as it is used in dedicated head and neck scanners. Concepts related to CBCT acquisition geometry, flat panel detection, and image quality will be explored in detail. Particular emphasis will be placed on technical limitations to low-contrast detectability and radiation dose. Proposed methods of x-ray scatter reduction will also be discussed.

Incorporating geometric ray tracing to generate initial conditions for intensity modulated arc therapy optimization

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

Oliver, Mike; Gladwish, Adam; Craig, Jeff

2008-07-15

Purpose and background: Intensity modulated arc therapy (IMAT) is a rotational variant of Intensity modulated radiation therapy (IMRT) that is achieved by allowing the multileaf collimator (MLC) positions to vary as the gantry rotates around the patient. This work describes a method to generate an IMAT plan through the use of a fast ray tracing technique based on dosimetric and geometric information for setting initial MLC leaf positions prior to final IMAT optimization. Methods and materials: Three steps were used to generate an IMAT plan. The first step was to generate arcs based on anatomical contours. The second step wasmore » to generate ray importance factor (RIF) maps by ray tracing the dose distribution inside the planning target volume (PTV) to modify the MLC leaf positions of the anatomical arcs to reduce the maximum dose inside the PTV. The RIF maps were also segmented to create a new set of arcs to improve the dose to low dose voxels within the PTV. In the third step, the MLC leaf positions from all arcs were put through a leaf position optimization (LPO) algorithm and brought into a fast Monte Carlo dose calculation engine for a final dose calculation. The method was applied to two phantom cases, a clinical prostate case and the Radiological Physics Center (RPC)'s head and neck phantom. The authors assessed the plan improvements achieved by each step and compared plans with and without using RIF. They also compared the IMAT plan with an IMRT plan for the RPC phantom. Results: All plans that incorporated RIF and LPO had lower objective function values than those that incorporated LPO only. The objective function value was reduced by about 15% after the generation of RIF arcs and 52% after generation of RIF arcs and leaf position optimization. The IMAT plan for the RPC phantom had similar dose coverage for PTV1 and PTV2 (the same dose volume histogram curves), however, slightly lower dose to the normal tissues compared to a six-field IMRT plan. Conclusion: The use of a ray importance factor can generate initial IMAT arcs efficiently for further MLC leaf position optimization to obtain more favorable IMAT plan.« less

Physical dose of therapeutic exercises in institutional neck rehabilitation.

PubMed

Wasenius, Niko; Karapalo, Teppo; Sjögren, Tuulikki; Pekkonen, Mika; Mälkiä, Esko

2013-03-01

To determine the intensity and volume of therapeutic exercises during a standard 13-day inpatient neck rehabilitation course in relation to overall physical activity in rehabilitation and everyday life. Cross-sectional study. Subjects (n = 19; 16 women and 3 men; mean age 48.6 years, standard deviation (SD) 6.6) with chronic non-specific neck pain were recruited from two inpatient neck rehabilitation courses. Intensity and volume of therapeutic exercises and physical activity were measured in metabolic equivalents (METs) with an objective measurement device and all-time recall questionnaire. Maximum oxygen uptake was determined in METs (METc) by direct maximal cycle ergometer. Subjects' mean METc was 7.2 METs (SD 1.4) or 25.3 ml/kg/min (SD 4.8). Intensity of all therapeutic exercises was 1.9 METs or 27 %METc (SD 5.1) and volume 7.7 MET-hours/week. Intensity of specific neck and shoulder exercises was 2.0 METs or 28 %METc (SD 5.4) and volume 2.5 MET-hours/week. In addition, subjects were more active in everyday life than in inpatient rehabilitation. The therapeutic exercise dose failed to reach previously reported target values for pain relief. The dose of therapeutic exercises and confounding physical activity should be carefully controlled in pain rehabilitation programmes.

Dose-shaping using targeted sparse optimization

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

Sayre, George A.; Ruan, Dan

2013-07-15

Purpose: Dose volume histograms (DVHs) are common tools in radiation therapy treatment planning to characterize plan quality. As statistical metrics, DVHs provide a compact summary of the underlying plan at the cost of losing spatial information: the same or similar dose-volume histograms can arise from substantially different spatial dose maps. This is exactly the reason why physicians and physicists scrutinize dose maps even after they satisfy all DVH endpoints numerically. However, up to this point, little has been done to control spatial phenomena, such as the spatial distribution of hot spots, which has significant clinical implications. To this end, themore » authors propose a novel objective function that enables a more direct tradeoff between target coverage, organ-sparing, and planning target volume (PTV) homogeneity, and presents our findings from four prostate cases, a pancreas case, and a head-and-neck case to illustrate the advantages and general applicability of our method.Methods: In designing the energy minimization objective (E{sub tot}{sup sparse}), the authors utilized the following robust cost functions: (1) an asymmetric linear well function to allow differential penalties for underdose, relaxation of prescription dose, and overdose in the PTV; (2) a two-piece linear function to heavily penalize high dose and mildly penalize low and intermediate dose in organs-at risk (OARs); and (3) a total variation energy, i.e., the L{sub 1} norm applied to the first-order approximation of the dose gradient in the PTV. By minimizing a weighted sum of these robust costs, general conformity to dose prescription and dose-gradient prescription is achieved while encouraging prescription violations to follow a Laplace distribution. In contrast, conventional quadratic objectives are associated with a Gaussian distribution of violations, which is less forgiving to large violations of prescription than the Laplace distribution. As a result, the proposed objective E{sub tot}{sup sparse} improves tradeoff between planning goals by 'sacrificing' voxels that have already been violated to improve PTV coverage, PTV homogeneity, and/or OAR-sparing. In doing so, overall plan quality is increased since these large violations only arise if a net reduction in E{sub tot}{sup sparse} occurs as a result. For example, large violations to dose prescription in the PTV in E{sub tot}{sup sparse}-optimized plans will naturally localize to voxels in and around PTV-OAR overlaps where OAR-sparing may be increased without compromising target coverage. The authors compared the results of our method and the corresponding clinical plans using analyses of DVH plots, dose maps, and two quantitative metrics that quantify PTV homogeneity and overdose. These metrics do not penalize underdose since E{sub tot}{sup sparse}-optimized plans were planned such that their target coverage was similar or better than that of the clinical plans. Finally, plan deliverability was assessed with the 2D modulation index.Results: The proposed method was implemented using IBM's CPLEX optimization package (ILOG CPLEX, Sunnyvale, CA) and required 1-4 min to solve with a 12-core Intel i7 processor. In the testing procedure, the authors optimized for several points on the Pareto surface of four 7-field 6MV prostate cases that were optimized for different levels of PTV homogeneity and OAR-sparing. The generated results were compared against each other and the clinical plan by analyzing their DVH plots and dose maps. After developing intuition by planning the four prostate cases, which had relatively few tradeoffs, the authors applied our method to a 7-field 6 MV pancreas case and a 9-field 6MV head-and-neck case to test the potential impact of our method on more challenging cases. The authors found that our formulation: (1) provided excellent flexibility for balancing OAR-sparing with PTV homogeneity; and (2) permitted the dose planner more control over the evolution of the PTV's spatial dose distribution than conventional objective functions. In particular, E{sub tot}{sup sparse}-optimized plans for the pancreas case and head-and-neck case exhibited substantially improved sparing of the spinal cord and parotid glands, respectively, while maintaining or improving sparing for other OARs and markedly improving PTV homogeneity. Plan deliverability for E{sub tot}{sup sparse}-optimized plans was shown to be better than their associated clinical plans, according to the two-dimensional modulation index.Conclusions: These results suggest that our formulation may be used to improve dose-shaping and OAR-sparing for complicated disease sites, such as the pancreas or head and neck. Furthermore, our objective function and constraints are linear and constitute a linear program, which converges to the global minimum quickly, and can be easily implemented in treatment planning software. Thus, the authors expect fast translation of our method to the clinic where it may have a positive impact on plan quality for challenging disease sites.« less

In vivo dosimetry with optically stimulated luminescent dosimeters for conformal and intensity-modulated radiation therapy: A 2-year multicenter cohort study.

PubMed

Riegel, Adam C; Chen, Yu; Kapur, Ajay; Apicello, Laura; Kuruvilla, Abraham; Rea, Anthony J; Jamshidi, Abolghassem; Potters, Louis

Optically stimulated luminescent dosimeters (OSLDs) are utilized for in vivo dosimetry (IVD) of modern radiation therapy techniques such as intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT). Dosimetric precision achieved with conventional techniques may not be attainable. In this work, we measured accuracy and precision for a large sample of clinical OSLD-based IVD measurements. Weekly IVD measurements were collected from 4 linear accelerators for 2 years and were expressed as percent differences from planned doses. After outlier analysis, 10,224 measurements were grouped in the following way: overall, modality (photons, electrons), treatment technique (3-dimensional [3D] conformal, field-in-field intensity modulation, inverse-planned IMRT, and VMAT), placement location (gantry angle, cardinality, and central axis positioning), and anatomical site (prostate, breast, head and neck, pelvis, lung, rectum and anus, brain, abdomen, esophagus, and bladder). Distributions were modeled via a Gaussian function. Fitting was performed with least squares, and goodness-of-fit was assessed with the coefficient of determination. Model means (μ) and standard deviations (σ) were calculated. Sample means and variances were compared for statistical significance by analysis of variance and the Levene tests (α = 0.05). Overall, μ ± σ was 0.3 ± 10.3%. Precision for electron measurements (6.9%) was significantly better than for photons (10.5%). Precision varied significantly among treatment techniques (P < .0001) with field-in-field lowest (σ = 7.2%) and IMRT and VMAT highest (σ = 11.9% and 13.4%, respectively). Treatment site models with goodness-of-fit greater than 0.90 (6 of 10) yielded accuracy within ±3%, except for head and neck (μ = -3.7%). Precision varied with treatment site (range, 7.3%-13.0%), with breast and head and neck yielding the best and worst precision, respectively. Placement on the central axis of cardinal gantry angles yielded more precise results (σ = 8.5%) compared with other locations (range, 10.5%-11.4%). Accuracy of ±3% was achievable. Precision ranged from 6.9% to 13.4% depending on modality, technique, and treatment site. Simple, standardized locations may improve IVD precision. These findings may aid development of patient-specific tolerances for OSLD-based IVD. Copyright © 2016 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.

Monte Carlo evaluation of RapidArc™ oropharynx treatment planning strategies for sparing of midline structures

NASA Astrophysics Data System (ADS)

Bush, K.; Zavgorodni, S.; Gagne, I.; Townson, R.; Ansbacher, W.; Beckham, W.

2010-08-01

The aim of the study was to perform the Monte Carlo (MC) evaluation of RapidArc™ (Varian Medical Systems, Palo Alto, CA) dose calculations for four oropharynx midline sparing planning strategies. Six patients with squamous cell cancer of the oropharynx were each planned with four RapidArc head and neck treatment strategies consisting of single and double photon arcs. In each case, RTOG0522 protocol objectives were used during planning optimization. Dose calculations performed with the analytical anisotropic algorithm (AAA) are compared against BEAMnrc/DOSXYZnrc dose calculations for the 24-plan dataset. Mean dose and dose-to-98%-of-structure-volume (D98%) were used as metrics in the evaluation of dose to planning target volumes (PTVs). Mean dose and dose-to-2%-of-structure-volume (D2%) were used to evaluate dose differences within organs at risk (OAR). Differences in the conformity index (CI) and the homogeneity index (HI) as well as 3D dose distributions were also observed. AAA calculated PTV mean dose, D98%, and HIs showed very good agreement with MC dose calculations within the 0.8% MC (statistical) calculation uncertainty. Regional node volume (PTV-80%) mean dose and D98% were found to be overestimated (1.3%, σ = 0.8% and 2.3%, σ = 0.8%, respectively) by the AAA with respect to MC calculations. Mean dose and D2% to OAR were also observed to be consistently overestimated by the AAA. Increasing dose calculation differences were found in planning strategies exhibiting a higher overall fluence modulation. From the plan dataset, the largest local dose differences were observed in heavily shielded regions and within the esophageal and sinus cavities. AAA dose calculations as implemented in RapidArc™ demonstrate excellent agreement with MC calculations in unshielded regions containing moderate inhomogeneities. Acceptable agreement is achieved in regions of increased MLC shielding. Differences in dose are attributed to inaccuracies in the AAA-modulated fluence modeling, modeling of material inhomogeneities and dose deposition within low-density materials. The use of MC dose calculations leads to the same general conclusion as using AAA that a two arc delivery with limited collimator opening can provide the greatest amount of midline sparing compared to the other techniques investigated.

Gamma-index method sensitivity for gauging plan delivery accuracy of volumetric modulated arc therapy.

PubMed

Park, Jong In; Park, Jong Min; Kim, Jung-In; Park, So-Yeon; Ye, Sung-Joon

2015-12-01

The aim of this study was to investigate the sensitivity of the gamma-index method according to various gamma criteria for volumetric modulated arc therapy (VMAT). Twenty head and neck (HN) and twenty prostate VMAT plans were retrospectively selected for this study. Both global and local 2D gamma evaluations were performed with criteria of 3%/3 mm, 2%/2 mm, 1%/2 mm and 2%/1 mm. In this study, the global and local gamma-index calculated the differences in doses relative to the maximum dose and the dose at the current measurement point, respectively. Using log files acquired during delivery, the differences in parameters at every control point between the VMAT plans and the log files were acquired. The differences in dose-volumetric parameters between reconstructed VMAT plans using the log files and the original VMAT plans were calculated. The Spearman's rank correlation coefficients (rs) were calculated between the passing rates and those differences. Considerable correlations with statistical significances were observed between global 1%/2 mm, local 1%/2 mm and local 2%/1 mm and the MLC position differences (rs = -0.712, -0.628 and -0.581). The numbers of rs values with statistical significance between the passing rates and the changes in dose-volumetric parameters were largest in global 2%/2 mm (n = 16), global 2%/1 mm (n = 15) and local 2%/1 mm (n = 13) criteria. Local gamma-index method with 2%/1 mm generally showed higher sensitivity to detect deviations between a VMAT plan and the delivery of the VMAT plan. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

SU-F-T-202: An Evaluation Method of Lifetime Attributable Risk for Comparing Between Proton Beam Therapy and Intensity Modulated X-Ray Therapy for Pediatric Cancer Patients by Averaging Four Dose-Response Models for Carcinoma Induction

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

Tamura, M; Shirato, H; Ito, Y

Purpose: To examine how much lifetime attributable risk (LAR) as an in silico surrogate marker of radiation-induced secondary cancer would be lowered by using proton beam therapy (PBT) in place of intensity modulated x-ray therapy (IMXT) in pediatric patients. Methods: From 242 pediatric patients with cancers who were treated with PBT, 26 patients were selected by random sampling after stratification into four categories: a) brain, head, and neck, b) thoracic, c) abdominal, and d) whole craniospinal (WCNS) irradiation. IMXT was re-planned using the same computed tomography and region of interest. Using dose volume histogram (DVH) of PBT and IMXT, themore » LAR of Schneider et al. was calculated for the same patient. The published four dose-response models for carcinoma induction: i) full model, ii) bell-shaped model, iii) plateau model, and ix) linear model were tested for organs at risk. In the case that more than one dose-response model was available, the LAR for this patient was calculated by averaging LAR for each dose-response model. Results: Calculation of the LARs of PBT and IMXT based on DVH was feasible for all patients. The mean±standard deviation of the cumulative LAR difference between PBT and IMXT for the four categories was a) 0.77±0.44% (n=7, p=0.0037), b) 23.1±17.2%,(n=8, p=0.0067), c) 16.4±19.8% (n=8, p=0.0525), and d) 49.9±21.2% (n=3, p=0.0275, one tailed t-test), respectively. The LAR was significantly lower by PBT than IMXT for the the brain, head, and neck region, thoracic region, and whole craniospinal irradiation. Conclusion: In pediatric patients who had undergone PBT, the LAR of PBT was significantly lower than the LAR of IMXT estimated by in silico modeling. This method was suggested to be useful as an in silico surrogate marker of secondary cancer induced by different radiotherapy techniques. This research was supported by the Translational Research Network Program, JSPS KAKENHI Grant No. 15H04768 and the Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, founded by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.« less

Image guidance during head-and-neck cancer radiation therapy: analysis of alignment trends with in-room cone-beam computed tomography scans.

PubMed

Zumsteg, Zachary; DeMarco, John; Lee, Steve P; Steinberg, Michael L; Lin, Chun Shu; McBride, William; Lin, Kevin; Wang, Pin-Chieh; Kupelian, Patrick; Lee, Percy

2012-06-01

On-board cone-beam computed tomography (CBCT) is currently available for alignment of patients with head-and-neck cancer before radiotherapy. However, daily CBCT is time intensive and increases the overall radiation dose. We assessed the feasibility of using the average couch shifts from the first several CBCTs to estimate and correct for the presumed systematic setup error. 56 patients with head-and-neck cancer who received daily CBCT before intensity-modulated radiation therapy had recorded shift values in the medial-lateral, superior-inferior, and anterior-posterior dimensions. The average displacements in each direction were calculated for each patient based on the first five or 10 CBCT shifts and were presumed to represent the systematic setup error. The residual error after this correction was determined by subtracting the calculated shifts from the shifts obtained using daily CBCT. The magnitude of the average daily residual three-dimensional (3D) error was 4.8 ± 1.4 mm, 3.9 ± 1.3 mm, and 3.7 ± 1.1 mm for uncorrected, five CBCT corrected, and 10 CBCT corrected protocols, respectively. With no image guidance, 40.8% of fractions would have been >5 mm off target. Using the first five CBCT shifts to correct subsequent fractions, this percentage decreased to 19.0% of all fractions delivered and decreased the percentage of patients with average daily 3D errors >5 mm from 35.7% to 14.3% vs. no image guidance. Using an average of the first 10 CBCT shifts did not significantly improve this outcome. Using the first five CBCT shift measurements as an estimation of the systematic setup error improves daily setup accuracy for a subset of patients with head-and-neck cancer receiving intensity-modulated radiation therapy and primarily benefited those with large 3D correction vectors (>5 mm). Daily CBCT is still necessary until methods are developed that more accurately determine which patients may benefit from alternative imaging strategies. Copyright © 2012 Elsevier Inc. All rights reserved.

Outcomes of Patients With Head-and-Neck Cancer of Unknown Primary Origin Treated With Intensity-Modulated Radiotherapy

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

Shoushtari, Asal; Saylor, Drew; Kerr, Kara-Lynne

2011-11-01

Purpose: To analyze survival, failure patterns, and toxicity in patients with head-and-neck carcinoma of unknown primary origin (HNCUP) treated with intensity-modulated radiotherapy (IMRT). Methods and materials: Records from 27 patients with HNCUP treated during the period 2002-2008 with IMRT were reviewed retrospectively. Nodal staging ranged from N1 to N3. The mean preoperative dose to gross or suspected disease, Waldeyer's ring, and uninvolved bilateral cervical nodes was 59.4, 53.5, and 51.0 Gy, respectively. Sixteen patients underwent neck dissection after radiation and 4 patients before radiation. Eight patients with advanced nodal disease (N2b-c, N3) or extracapsular extension received chemotherapy. Results: With amore » median follow-up of 41.9 months (range, 25.3-93.9 months) for nondeceased patients, the 5-year actuarial overall survival, disease-free survival, and nodal control rates were 70.9%, 85.2%, and 88.5%, respectively. Actuarial disease-free survival rates for N1, N2, and N3 disease were 100%, 94.1%, and 50.0%, respectively, at 5 years. When stratified by nonadvanced (N1, N2a nodal disease without extracapsular spread) vs. advanced nodal disease (N2b, N2c, N3), the 5-year actuarial disease-free survival rate for the nonadvanced nodal disease group was 100%, whereas for the advanced nodal disease group it was significantly lower at 66.7% (p = 0.017). Three nodal recurrences were observed: in 1 patient with bulky N2b disease and 2 in patients with N3 disease. No nodal failures occurred in patients with N1 or N2a disease who received only radiation and surgery. Conclusion: Definitive IMRT to 50-56 Gy followed by neck dissection results in excellent nodal control and overall and disease-free survival, with acceptable toxicity for patients with T0N1 or nonbulky T0N2a disease without extracapsular spread. Patients with extracapsular spread, advanced N2 disease, or N3 disease may benefit from concurrent chemotherapy, targeted therapeutic agents, or accelerated radiation regimens in addition to surgery.« less

Optimized Volumetric Modulated Arc Therapy Versus 3D-CRT for Early Stage Mediastinal Hodgkin Lymphoma Without Axillary Involvement: A Comparison of Second Cancers and Heart Disease Risk

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

Filippi, Andrea Riccardo, E-mail: andreariccardo.filippi@unito.it; Ragona, Riccardo; Piva, Cristina

Purpose: The purpose of this study was to evaluate the risks of second cancers and cardiovascular diseases associated with an optimized volumetric modulated arc therapy (VMAT) planning solution in a selected cohort of stage I/II Hodgkin lymphoma (HL) patients treated with either involved-node or involved-site radiation therapy in comparison with 3-dimensional conformal radiation therapy (3D-CRT). Methods and Materials: Thirty-eight patients (13 males and 25 females) were included. Disease extent was mediastinum alone (n=8, 21.1%); mediastinum plus unilateral neck (n=19, 50%); mediastinum plus bilateral neck (n=11, 29.9%). Prescription dose was 30 Gy in 2-Gy fractions. Only 5 patients had mediastinal bulkymore » disease at diagnosis (13.1%). Anteroposterior 3D-CRT was compared with a multiarc optimized VMAT solution. Lung, breast, and thyroid cancer risks were estimated by calculating a lifetime attributable risk (LAR), with a LAR ratio (LAR{sub VMAT}-to-LAR{sub 3D-CRT}) as a comparative measure. Cardiac toxicity risks were estimated by calculating absolute excess risk (AER). Results: The LAR ratio favored 3D-CRT for lung cancer induction risk in mediastinal alone (P=.004) and mediastinal plus unilateral neck (P=.02) presentations. LAR ratio for breast cancer was lower for VMAT in mediastinal plus bilateral neck presentations (P=.02), without differences for other sites. For thyroid cancer, no significant differences were observed, regardless of anatomical presentation. A significantly lower AER of cardiac (P=.038) and valvular diseases (P<.0001) was observed for VMAT regardless of disease extent. Conclusions: In a cohort of patients with favorable characteristics in terms of disease extent at diagnosis (large prevalence of nonbulky presentations without axillary involvement), optimized VMAT reduced heart disease risk with comparable risks of thyroid and breast cancer, with an increase in lung cancer induction probability. The results are however strongly influenced by the different anatomical presentations, supporting an individualized approach.« less

Multifield Optimization Intensity Modulated Proton Therapy for Head and Neck Tumors: A Translation to Practice

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

Frank, Steven J., E-mail: sjfrank@mdanderson.org; Cox, James D.; Gillin, Michael

2014-07-15

Background: We report the first clinical experience and toxicity of multifield optimization (MFO) intensity modulated proton therapy (IMPT) for patients with head and neck tumors. Methods and Materials: Fifteen consecutive patients with head and neck cancer underwent MFO-IMPT with active scanning beam proton therapy. Patients with squamous cell carcinoma (SCC) had comprehensive treatment extending from the base of the skull to the clavicle. The doses for chemoradiation therapy and radiation therapy alone were 70 Gy and 66 Gy, respectively. The robustness of each treatment plan was also analyzed to evaluate sensitivity to uncertainties associated with variations in patient setup and the effectmore » of uncertainties with proton beam range in patients. Proton beam energies during treatment ranged from 72.5 to 221.8 MeV. Spot sizes varied depending on the beam energy and depth of the target, and the scanning nozzle delivered the spot scanning treatment “spot by spot” and “layer by layer.” Results: Ten patients presented with SCC and 5 with adenoid cystic carcinoma. All 15 patients were able to complete treatment with MFO-IMPT, with no need for treatment breaks and no hospitalizations. There were no treatment-related deaths, and with a median follow-up time of 28 months (range, 20-35 months), the overall clinical complete response rate was 93.3% (95% confidence interval, 68.1%-99.8%). Xerostomia occurred in all 15 patients as follows: grade 1 in 10 patients, grade 2 in 4 patients, and grade 3 in 1 patient. Mucositis within the planning target volumes was seen during the treatment of all patients: grade 1 in 1 patient, grade 2 in 8 patients, and grade 3 in 6 patients. No patient experienced grade 2 or higher anterior oral mucositis. Conclusions: To our knowledge, this is the first clinical report of MFO-IMPT for head and neck tumors. Early clinical outcomes are encouraging and warrant further investigation of proton therapy in prospective clinical trials.« less

Assessing dose rate distributions in VMAT plans

NASA Astrophysics Data System (ADS)

Mackeprang, P.-H.; Volken, W.; Terribilini, D.; Frauchiger, D.; Zaugg, K.; Aebersold, D. M.; Fix, M. K.; Manser, P.

2016-04-01

Dose rate is an essential factor in radiobiology. As modern radiotherapy delivery techniques such as volumetric modulated arc therapy (VMAT) introduce dynamic modulation of the dose rate, it is important to assess the changes in dose rate. Both the rate of monitor units per minute (MU rate) and collimation are varied over the course of a fraction, leading to different dose rates in every voxel of the calculation volume at any point in time during dose delivery. Given the radiotherapy plan and machine specific limitations, a VMAT treatment plan can be split into arc sectors between Digital Imaging and Communications in Medicine control points (CPs) of constant and known MU rate. By calculating dose distributions in each of these arc sectors independently and multiplying them with the MU rate, the dose rate in every single voxel at every time point during the fraction can be calculated. Independently calculated and then summed dose distributions per arc sector were compared to the whole arc dose calculation for validation. Dose measurements and video analysis were performed to validate the calculated datasets. A clinical head and neck, cranial and liver case were analyzed using the tool developed. Measurement validation of synthetic test cases showed linac agreement to precalculated arc sector times within  ±0.4 s and doses  ±0.1 MU (one standard deviation). Two methods for the visualization of dose rate datasets were developed: the first method plots a two-dimensional (2D) histogram of the number of voxels receiving a given dose rate over the course of the arc treatment delivery. In similarity to treatment planning system display of dose, the second method displays the dose rate as color wash on top of the corresponding computed tomography image, allowing the user to scroll through the variation over time. Examining clinical cases showed dose rates spread over a continuous spectrum, with mean dose rates hardly exceeding 100 cGy min-1 for conventional fractionation. A tool to analyze dose rate distributions in VMAT plans with sub-second accuracy was successfully developed and validated. Dose rates encountered in clinical VMAT test cases show a continuous spectrum with a mean less than or near 100 cGy min-1 for conventional fractionation.

SU-E-T-196: Comparative Analysis of Surface Dose Measurements Using MOSFET Detector and Dose Predicted by Eclipse - AAA with Varying Dose Calculation Grid Size

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

Badkul, R; Nejaiman, S; Pokhrel, D

2015-06-15

Purpose: Skin dose can be the limiting factor and fairly common reason to interrupt the treatment, especially for treating head-and-neck with Intensity-modulated-radiation-therapy(IMRT) or Volumetrically-modulated - arc-therapy (VMAT) and breast with tangentially-directed-beams. Aim of this study was to investigate accuracy of near-surface dose predicted by Eclipse treatment-planning-system (TPS) using Anisotropic-Analytic Algorithm (AAA)with varying calculation grid-size and comparing with metal-oxide-semiconductor-field-effect-transistors(MOSFETs)measurements for a range of clinical-conditions (open-field,dynamic-wedge, physical-wedge, IMRT,VMAT). Methods: QUASAR™-Body-Phantom was used in this study with oval curved-surfaces to mimic breast, chest wall and head-and-neck sites.A CT-scan was obtained with five radio-opaque markers(ROM) placed on the surface of phantom to mimic themore » range of incident angles for measurements and dose prediction using 2mm slice thickness.At each ROM, small structure(1mmx2mm) were contoured to obtain mean-doses from TPS.Calculations were performed for open-field,dynamic-wedge,physical-wedge,IMRT and VMAT using Varian-21EX,6&15MV photons using twogrid-sizes:2.5mm and 1mm.Calibration checks were performed to ensure that MOSFETs response were within ±5%.Surface-doses were measured at five locations and compared with TPS calculations. Results: For 6MV: 2.5mm grid-size,mean calculated doses(MCD)were higher by 10%(±7.6),10%(±7.6),20%(±8.5),40%(±7.5),30%(±6.9) and for 1mm grid-size MCD were higher by 0%(±5.7),0%(±4.2),0%(±5.5),1.2%(±5.0),1.1% (±7.8) for open-field,dynamic-wedge,physical-wedge,IMRT,VMAT respectively.For 15MV: 2.5mm grid-size,MCD were higher by 30%(±14.6),30%(±14.6),30%(±14.0),40%(±11.0),30%(±3.5)and for 1mm grid-size MCD were higher by 10% (±10.6), 10%(±9.8),10%(±8.0),30%(±7.8),10%(±3.8) for open-field, dynamic-wedge, physical-wedge, IMRT, VMAT respectively.For 6MV, 86% and 56% of all measured values agreed better than ±20% for 1mm and 2.5mm grid-sizes respectively. For 18MV, 56% and 18% of all measured-values agreed better than ±20% for 1mm and 2.5mm grid-sizes respectively. Conclusion: Reliable Skin-dose calculations by TPS can be very difficult due to steep dose-gradient and inaccurate beam-modelling in buildup region.Our results showed that Eclipse over-estimates surface-dose.Impact of grid-size is also significant,surface-dose increased up to 40% from 1mm to 2.5mm,however, 1mm calculated-values closely agrees with measurements. Due to large uncertnities in skin-dose predictions from TPS, outmost caution must be exercised when skin dose is evaluated,a sufficiently smaller grid-size(1mm)can improve the accuracy and MOSFETs can be used for verification.« less

A novel conformity index for intensity modulated radiation therapy plan evaluation

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

Cheung, Fion W. K.; Law, Maria Y. Y.; Medical Physics and Research Department, Hong Kong Sanatorium and Hospital, 999077 Hong Kong

2012-09-15

Purpose: Intensity modulated radiation therapy (IMRT) has gained popularity in the treatment of cancers. Manual evaluation of IMRT plans for head-and-neck cancers has been especially challenging necessitating efficient and objective assessment tools. In this work, the authors address this issue by developing a personalized conformity index (CI) for comparison of IMRT plans for head-and-neck cancers and evaluating its plan quality discerning power in comparison with other widely used CIs. Methods: A two-dimensional CI with dose and distance incorporated (CI{sub DD}) was developed using the MATLAB program language, to quantify the planning target volume (PTV) coverage. Valuable information contained in themore » digital imaging and communication in medicine (DICOM) RT objects were harvested for computation of each of the CI{sub DD} components. Apart from the dose penalty factor, a distance-based exponential function was employed by varying the penalty weight associated with the location of cold spots within the PTV. With the goal of deriving a customized penalty factor, the distances between individual pixel and its nearest PTV boundary was found. Using the exponential function, the impact of distance penalty was substantially larger for cold spots closer to the PTV centroid but petered out quickly wherever they were situated in the vicinity of PTV border. In order to evaluate the CI{sub DD} scoring system, three CT image data sets of nasopharyngeal carcinoma (NPC) patients were collected. Ten IMRT plans with degrading qualities were generated from each dataset and were ranked based on CI{sub DD} and other existing indices. The coefficient of variance was calculated for each dataset to compare the degree of variation. Results: The CI{sub DD} scoring system that considered spatial importance of each voxel within the PTV was successfully developed. The results demonstrated that the CI{sub DD} including four discrete factors could provide accurate rankings of plan quality by examining the relative importance of each cold spot within the PTVs. Apart from the dose penalty factor, a distance-based exponential function was employed taking the specific tumor geometry into account. Compared with other commonly used CIs, the CI{sub DD} resulted in the largest coefficient of variance among the ten IMRT plans for each dataset, indicating that its discerning power was the best among the CIs being compared. Conclusions: The CI{sub DD} scoring system was successfully developed to incorporate patient-specific spatial dose information and provide a geometry-based physical index for comparison of IMRT plans for head-and-neck cancers. By taking individual tumor geometry into account, the superiority of CI{sub DD} in plan discerning power was demonstrated. The use of CI{sub DD} could provide an effective means of benchmarking performance, reducing treatment plan variability, and advancing the quality of current IMRT planning.« less

Dosimetry on the Spacelab missions IML1 and IML2, and D2 and on MIR.

PubMed

Reitz, G; Beaujean, R; Heilmann, C; Kopp, J; Leicher, M; Strauch, K

1996-11-01

Detector packages consisting of plastic nuclear track detectors, nuclear emulsions, and thermoluminescence detectors were exposed inside BIORACK during the Spacelab missions IML1 and IML2, in different sections of the MIR space station, and inside the Spacelab module at rack front panels or stowage lockers and in the Spacelab tunnel during D2. In addition, during D2, each Payload Specialist (PS) has worn three permanent detector packages; one at the neck; one at the waist; and one at the ankle. Total dose measurements, particle fluence rate and LET spectra, number of nuclear disintegrations and neutron dose from this exposure are given in this report. The results are compared to theoretical calculations and to previous missions results. The dose equivalent (total radiation exposure) received by the PSs were calculated from the measurements and range from 190 to 770 microSv d-1. Finally, a cursory investigation of results from a particle telescope from two silicon detectors, first used in the last BIORACK mission on STS76, is reported.

Interactive Dose Shaping - efficient strategies for CPU-based real-time treatment planning

NASA Astrophysics Data System (ADS)

Ziegenhein, P.; Kamerling, C. P.; Oelfke, U.

2014-03-01

Conventional intensity modulated radiation therapy (IMRT) treatment planning is based on the traditional concept of iterative optimization using an objective function specified by dose volume histogram constraints for pre-segmented VOIs. This indirect approach suffers from unavoidable shortcomings: i) The control of local dose features is limited to segmented VOIs. ii) Any objective function is a mathematical measure of the plan quality, i.e., is not able to define the clinically optimal treatment plan. iii) Adapting an existing plan to changed patient anatomy as detected by IGRT procedures is difficult. To overcome these shortcomings, we introduce the method of Interactive Dose Shaping (IDS) as a new paradigm for IMRT treatment planning. IDS allows for a direct and interactive manipulation of local dose features in real-time. The key element driving the IDS process is a two-step Dose Modification and Recovery (DMR) strategy: A local dose modification is initiated by the user which translates into modified fluence patterns. This also affects existing desired dose features elsewhere which is compensated by a heuristic recovery process. The IDS paradigm was implemented together with a CPU-based ultra-fast dose calculation and a 3D GUI for dose manipulation and visualization. A local dose feature can be implemented via the DMR strategy within 1-2 seconds. By imposing a series of local dose features, equal plan qualities could be achieved compared to conventional planning for prostate and head and neck cases within 1-2 minutes. The idea of Interactive Dose Shaping for treatment planning has been introduced and first applications of this concept have been realized.

SU-F-T-207: Does the Greater Flexibility of Pencil Beam Scanning Reduce the Need for a Proton Gantry?

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

Yan, S; Depauw, N; Flanz, J

2016-06-15

Purpose: Gantry-less proton treatment facility could lower the capital cost of proton therapy. This study investigates the dosimetric feasibility of using only coplanar pencil beam scanning (PBS) beams for those patients who had beam angles that would not have been deliverable without the gantry. Those coplanar beams are implemented on gantry-less horizontal beam-line with patients in sitting or standing positions. Methods: We have selected ten patients (seven head-and-neck, one thoracic, one abdominal and one pelvic case) with clinically delivered double scattering (DS) or PBS treatment plans with beam angles that were challenging to achieve without a gantry. After removing thesemore » beams angles, PBS plans were optimized for gantry-less intensity modulated proton therapy (IMPT) or single field optimization (SFO) with multi-criteria optimization (MCO). For head-and-neck patients who were treated by DS, we generated PBS plans with non-coplanar beams for comparison. Dose-volume-histograms (DVHs), target homogeneity index (HI), mean dose, D-2 and D-98 were reported. Robustness analysis was performed with ±2.5 mm setup errors and ±3.5% range uncertainties for three head-and-neck patients. Results: PBS-gantry-less plans provided more homogenous target coverage and significant improvements on organs-at-risk (OARs) sparing, compared to passive scattering treatments with a gantry. The PBS gantry-less treatments reduced the HI for target coverage by 1.3% to 47.2%, except for a suprasellar patient and a liver patient. The PBS-gantry-less plans reduced the D-mean of OARs by 3.6% to 67.4%. The PBS-gantry plans had similar target coverage and only marginal improvements on OAR sparing as compared to the PBS-gantry-less plans. These two PBS plans also had similar robustness relative to range uncertainties and setup errors. Conclusion: The gantry-less plans have with less mean dose to OARs and more homogeneous target coverage. Although the PBS-gantry plans have slightly improved target coverage and OARs sparing, the overall benefit of having a gantry to provide non-coplanar beams is debatable.« less

Impact of Salivary Gland Dosimetry on Post-IMRT Recovery of Saliva Output and Xerostomia Grade for Head-and-Neck Cancer Patients Treated With or Without Contralateral Submandibular Gland Sparing: A Longitudinal Study

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

Wang Zhonghe; Yan Chao; Zhang Zhiyuan

Purpose: To observe the recovery of saliva output and effect on xerostomia grade after intensity-modulated radiotherapy (IMRT) with or without contralateral submandibular gland (cSMG) sparing and to assess the impact of salivary gland dosimetry on this recovery among patients with head-and-neck cancer. Methods and Materials: Between May 2007 and May 2008, 52 patients with head-and-neck cancer received definitive (n = 5 patients) and postoperative (n = 47 patients) IMRT at our institution, with at least one parotid gland spared. Of these patients, 26 patients with a low risk of recurrence in the cSMG region underwent IMRT and had their cSMGsmore » spared (cSMG-sparing group). The remaining 26 high-risk patients had no cSMGs spared (cSMG-unspared group). Xerostomia grades and salivary flow rates were monitored at five time points (before IMRT and at 2, 6, 12, and 18 months after IMRT). Results: Average mean doses and mean volumes receiving 30 Gy (V30) of the cSMGs were lower in the cSMG-sparing group than in the cSMG-unspared group (mean dose, 20.4 Gy vs. 57.4 Gy; mean V30, 14.7% vs. 99.8%, respectively). Xerostomia grades at 2 and 6 months post-IMRT were also significantly lower among patients in the cSMG-sparing group than in the cSMG-unspared group, but differences were not significant at 12 and 18 months after IMRT. Patients in the cSMG-sparing group had significantly better mean unstimulated salivary flow rates at each time point post- IMRT as well as better mean stimulated salivary flow rates at 2 months post-IMRT. Conclusions: Recovery of saliva output and grade of xerostomia post-IMRT in patients whose cSMGs were spared were much better than in patients whose cSMGs were not spared. The influence of the mean doses to the cSMG and parotid gland on the recovery of saliva output was equivalent to that of the mean V30 to the glands.« less

Image guided radiation therapy applications for head and neck, prostate, and breast cancers using 3D ultrasound imaging and Monte Carlo dose calculations

NASA Astrophysics Data System (ADS)

Fraser, Danielle

In radiation therapy an uncertainty in the delivered dose always exists because anatomic changes are unpredictable and patient specific. Image guided radiation therapy (IGRT) relies on imaging in the treatment room to monitor the tumour and surrounding tissue to ensure their prescribed position in the radiation beam. The goal of this thesis was to determine the dosimetric impact on the misaligned radiation therapy target for three cancer sites due to common setup errors; organ motion, tumour tissue deformation, changes in body habitus, and treatment planning errors. For this purpose, a novel 3D ultrasound system (Restitu, Resonant Medical, Inc.) was used to acquire a reference image of the target in the computed tomography simulation room at the time of treatment planning, to acquire daily images in the treatment room at the time of treatment delivery, and to compare the daily images to the reference image. The measured differences in position and volume between daily and reference geometries were incorporated into Monte Carlo (MC) dose calculations. The EGSnrc (National Research Council, Canada) family of codes was used to model Varian linear accelerators and patient specific beam parameters, as well as to estimate the dose to the target and organs at risk under several different scenarios. After validating the necessity of MC dose calculations in the pelvic region, the impact of interfraction prostate motion, and subsequent patient realignment under the treatment beams, on the delivered dose was investigated. For 32 patients it is demonstrated that using 3D conformal radiation therapy techniques and a 7 mm margin, the prescribed dose to the prostate, rectum, and bladder is recovered within 0.5% of that planned when patient setup is corrected for prostate motion, despite the beams interacting with a new external surface and internal tissue boundaries. In collaboration with the manufacturer, the ultrasound system was adapted from transabdominal imaging to neck imaging. Two case studies of nasopharyngeal cancer are discussed. The deformation of disease-positive cervical lymph nodes was monitored throughout treatment. Node volumes shrunk to 17% of the initial volume, moved up 1.3 cm, and received up to a 12% lower dose than that prescribed. It is shown that difficulties in imaging soft tissue in the neck region are circumvented with ultrasound imaging, and after dosimetric verification it is argued that adaptive replanning may be more beneficial than patient realignment when intensity modulated radiation therapy techniques are used. Some of the largest dose delivery errors were found in external electron beam treatments for breast cancer patients who underwent breast conserving surgery. Inaccuracies in conventional treatment planning resulted in substantial target dose discrepancies of up to 88%. When patient setup errors, interfraction tumour bed motion, and tissue remodeling were considered, inadequate target coverage was exacerbated. This thesis quantifies the dose discrepancy between that prescribed and that delivered. I delve into detail for common IGRT treatment sites, and illuminate problems that have not received much attention for less common IGRT treatment sites.

Effective and organ doses from common CT examinations in one general hospital in Tehran, Iran

NASA Astrophysics Data System (ADS)

Khoramian, Daryoush; Hashemi, Bijan

2017-09-01

Purpose: It is well known that the main portion of artificial sources of ionizing radiation to human results from X-ray imaging techniques. However, reports carried out in various countries have indicated that most of their cumulative doses from artificial sources are due to CT examinations. Hence assessing doses resulted from CT examinations is highly recommended by national and international radiation protection agencies. The aim of this research has been to estimate the effective and organ doses in an average human according to 103 and 60 ICRP tissue weighting factor for six common protocols of Multi-Detector CT (MDCT) machine in a comprehensive training general hospital in Tehran/Iran. Methods: To calculate the patients' effective dose, the CT-Expo2.2 software was used. Organs/tissues and effective doses were determined for about 20 patients (totally 122 patients) for every one of six typical CT protocols of the head, neck, chest, abdomen-pelvis, pelvis and spine exams. In addition, the CT dosimetry index (CTDI) was measured in the standard 16 and 32 cm phantoms by using a calibrated pencil ionization chamber for the six protocols and by taking the average value of CT scan parameters used in the hospital compared with the CTDI values displayed on the console device of the machine. Results: The values of the effective dose based on the ICRP 103 tissue weighting factor were: 0.6, 2.0, 3.2, 4.2, 2.8, and 3.9 mSv and based on the ICRP 60 tissue weighting factor were: 0.9, 1.4, 3, 7.9, 4.8 and 5.1 mSv for the head, neck, chest, abdomen-pelvis, pelvis, spine CT exams respectively. Relative differences between those values were -22, 21, 23, -6, -31 and 16 percent for the head, neck, chest, abdomen-pelvis, pelvis, spine CT exams, respectively. The average value of CTDIv calculated for each protocol was: 27.32 ± 0.9, 18.08 ± 2.0, 7.36 ± 2.6, 8.84 ± 1.7, 9.13 ± 1.5, 10.42 ± 0.8 mGy for the head, neck, chest, abdomen-pelvis and spine CT exams, respectively. Conclusions: The highest organ doses delivered by various CT exams were received by brain (15.5 mSv), thyroid (19.00 mSv), lungs (9.3 mSv) and bladder (9.9 mSv), bladder (10.4 mSv), stomach (10.9 mSv) in the head, neck, chest, and the abdomen-pelvis, pelvis, and spine respectively. Except the neck and spine CT exams showing a higher effective dose compared to that reported in Netherlands, other exams indicated lower values compared to those reported by any other country.

Parotid Gland Function After Radiotherapy: The Combined Michigan and Utrecht Experience

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

Dijkema, Tim, E-mail: T.Dijkema@umcutrecht.n; Raaijmakers, Cornelis P.J.; Ten Haken, Randall K.

2010-10-01

Purpose: To analyze the combined and updated results from the University of Michigan and University Medical Center Utrecht on normal tissue complication probability (NTCP) of the parotid gland 1 year after radiotherapy (RT) for head-and-neck (HN) cancer. Patients and Methods: A total of 222 prospectively analyzed patients with various HN malignancies were treated with conventional and intensity-modulated RT. Stimulated individual parotid gland flow rates were measured before RT and 1 year after RT using Lashley cups at both centers. A flow ratio <25% of pretreatment was defined as a complication. The data were fitted to the Lyman-Kutcher-Burman model. Results: Amore » total of 384 parotid glands (Michigan: 157; Utrecht: 227 glands) was available for analysis 1 year after RT. Combined NTCP analysis based on mean dose resulted in a TD{sub 50} (uniform dose leading to 50% complication probability) of 39.9 Gy and m (steepness of the curve) of 0.40. The resulting NTCP curve had good qualitative agreement with the combined clinical data. Mean doses of 25-30 Gy were associated with 17-26% NTCP. Conclusions: A definite NTCP curve for parotid gland function 1 year after RT is presented, based on mean dose. No threshold dose was observed, and TD{sub 50} was equal to 40 Gy.« less

Radiation-Induced Oral Mucositis

PubMed Central

Maria, Osama Muhammad; Eliopoulos, Nicoletta; Muanza, Thierry

2017-01-01

Radiation-induced oral mucositis (RIOM) is a major dose-limiting toxicity in head and neck cancer patients. It is a normal tissue injury caused by radiation/radiotherapy (RT), which has marked adverse effects on patient quality of life and cancer therapy continuity. It is a challenge for radiation oncologists since it leads to cancer therapy interruption, poor local tumor control, and changes in dose fractionation. RIOM occurs in 100% of altered fractionation radiotherapy head and neck cancer patients. In the United Sates, its economic cost was estimated to reach 17,000.00 USD per patient with head and neck cancers. This review will discuss RIOM definition, epidemiology, impact and side effects, pathogenesis, scoring scales, diagnosis, differential diagnosis, prevention, and treatment. PMID:28589080

A GPU-accelerated and Monte Carlo-based intensity modulated proton therapy optimization system.

PubMed

Ma, Jiasen; Beltran, Chris; Seum Wan Chan Tseung, Hok; Herman, Michael G

2014-12-01

Conventional spot scanning intensity modulated proton therapy (IMPT) treatment planning systems (TPSs) optimize proton spot weights based on analytical dose calculations. These analytical dose calculations have been shown to have severe limitations in heterogeneous materials. Monte Carlo (MC) methods do not have these limitations; however, MC-based systems have been of limited clinical use due to the large number of beam spots in IMPT and the extremely long calculation time of traditional MC techniques. In this work, the authors present a clinically applicable IMPT TPS that utilizes a very fast MC calculation. An in-house graphics processing unit (GPU)-based MC dose calculation engine was employed to generate the dose influence map for each proton spot. With the MC generated influence map, a modified least-squares optimization method was used to achieve the desired dose volume histograms (DVHs). The intrinsic CT image resolution was adopted for voxelization in simulation and optimization to preserve spatial resolution. The optimizations were computed on a multi-GPU framework to mitigate the memory limitation issues for the large dose influence maps that resulted from maintaining the intrinsic CT resolution. The effects of tail cutoff and starting condition were studied and minimized in this work. For relatively large and complex three-field head and neck cases, i.e., >100,000 spots with a target volume of ∼ 1000 cm(3) and multiple surrounding critical structures, the optimization together with the initial MC dose influence map calculation was done in a clinically viable time frame (less than 30 min) on a GPU cluster consisting of 24 Nvidia GeForce GTX Titan cards. The in-house MC TPS plans were comparable to a commercial TPS plans based on DVH comparisons. A MC-based treatment planning system was developed. The treatment planning can be performed in a clinically viable time frame on a hardware system costing around 45,000 dollars. The fast calculation and optimization make the system easily expandable to robust and multicriteria optimization.

TU-D-209-06: Head and Neck Tissue Dose From X-Ray Scatter to Physicians Performing Cardiovascular Procedures

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

Fetterly, K; Schueler, B; Grams, M

Purpose: The purpose of this work was to characterize the spatial distribution of scatter radiation to the head and neck of a physician performing an x-ray interventional procedure and assess brain, eye lens, and carotid artery dose. Methods: Radiographic x-ray beams were tuned to match the peak energy (56 to 106 keV) and HVL (3.5 to 6.5 mm Al) of x-ray scatter originating from a patient during a fluoroscopic procedure. The radiographic beam was directed upon a Rando phantom from an inferior-left location to mimic a typical patient-operator geometric relationship. A lead-equivalent protective garment was secured to the phantom. Directmore » exposure Gafchromic film (XRQA2) was placed between the transverse plane layers of the head and neck region of the phantom and exposed with 4 scatter-equivalent radiographic beams. A 3×3 cm{sup 2} film placed at the left collar of the phantom was used to monitor incident dose in the position of a radiation monitoring badge. The films were converted to 2D dose distribution maps using FilmQA Pro software and an Epson 11000-XL scanner. The 2D dose distributions maps were normalized by the left collar dose and the percent of left collar dose (%LCD) was calculated for select tissues. Results: The dose maps had high dynamic range (10{sub 4}) and spatial detail. Considering all transverse planes and 4 scatter beam qualities, the median %LCD values were: whole brain 8.5%, left brain 13%, right brain 5.4%, left eye lens 67%, right eye lens 25%, left carotid artery 72%, and right carotid artery 28%. Conclusion: Scatter radiation dose to an operator can be simulated using a tuned radiographic beam and used to expose a phantom and Gafchromic film, thereby creating detailed 2D dose distribution maps. This work facilitates individualized estimation of dose to select head and neck tissues based on an operator’s radiation monitoring badge value.« 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

Acute Normal Tissue Reactions in Head-and-Neck Cancer Patients Treated With IMRT: Influence of Dose and Association With Genetic Polymorphisms in DNA DSB Repair Genes

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

Werbrouck, Joke; Ruyck, Kim de; Duprez, Frederic

2009-03-15

Purpose: To investigate the association between dose-related parameters and polymorphisms in DNA DSB repair genes XRCC3 (c.-1843A>G, c.562-14A>G, c.722C>T), Rad51 (c.-3429G>C, c.-3392G>T), Lig4 (c.26C>T, c.1704T>C), Ku70 (c.-1310C>G), and Ku80 (c.2110-2408G>A) and the occurrence of acute reactions after radiotherapy. Materials and Methods: The study population consisted of 88 intensity-modulated radiation therapy (IMRT)-treated head-and-neck cancer patients. Mucositis, dermatitis, and dysphagia were scored using the Common Terminology Criteria (CTC) for Adverse Events v.3.0 scale. The population was divided into a CTC0-2 and CTC3+ group for the analysis of each acute effect. The influence of the dose on critical structures was analyzed using dose-volumemore » histograms. Genotypes were determined by polymerase chain reaction (PCR) combined with restriction fragment length polymorphism or PCR-single base extension assays. Results: The mean dose (D{sub mean}) to the oral cavity and constrictor pharyngeus (PC) muscles was significantly associated with the development of mucositis and dysphagia, respectively. These parameters were considered confounding factors in the radiogenomics analyses. The XRCC3c.722CT/TT and Ku70c.-1310CG/GG genotypes were significantly associated with the development of severe dysphagia (CTC3+). No association was found between the investigated polymorphisms and the development of mucositis or dermatitis. A risk analysis model for severe dysphagia, which was developed based on the XRCC3c.722CT/TT and Ku70c.-1310CG/GG genotypes and the PC dose, showed a sensitivity of 78.6% and a specificity of 77.6%. Conclusions: The XRCC3c.722C>T and Ku70c.-1310C>G polymorphisms as well as the D{sub mean} to the PC muscles were highly associated with the development of severe dysphagia after IMRT. The prediction model developed using these parameters showed a high sensitivity and specificity.« less

Robust lung identification in MSCT via controlled flooding and shape constraints: dealing with anatomical and pathological specificity

NASA Astrophysics Data System (ADS)

Fetita, Catalin; Tarando, Sebastian; Brillet, Pierre-Yves; Grenier, Philippe A.

2016-03-01

Correct segmentation and labeling of lungs in thorax MSCT is a requirement in pulmonary/respiratory disease analysis as a basis for further processing or direct quantitative measures: lung texture classification, respiratory functional simulations, intrapulmonary vascular remodeling evaluation, detection of pleural effusion or subpleural opacities, are only few clinical applications related to this requirement. Whereas lung segmentation appears trivial for normal anatomo-pathological conditions, the presence of disease may complicate this task for fully-automated algorithms. The challenges come either from regional changes of lung texture opacity or from complex anatomic configurations (e.g., thin septum between lungs making difficult proper lung separation). They make difficult or even impossible the use of classic algorithms based on adaptive thresholding, 3-D connected component analysis and shape regularization. The objective of this work is to provide a robust segmentation approach of the pulmonary field, with individualized labeling of the lungs, able to overcome the mentioned limitations. The proposed approach relies on 3-D mathematical morphology and exploits the concept of controlled relief flooding (to identify contrasted lung areas) together with patient-specific shape properties for peripheral dense tissue detection. Tested on a database of 40 MSCT of pathological lungs, the proposed approach showed correct identification of lung areas with high sensitivity and specificity in locating peripheral dense opacities.

Inadequate increase in the volume of major epicardial coronary arteries compared with that in left ventricular mass. Novel concept for characterization of coronary arteries using 64-slice computed tomography.

PubMed

Ehara, Shoichi; Okuyama, Takuhiro; Shirai, Nobuyuki; Sugioka, Kenichi; Oe, Hiroki; Itoh, Toshihide; Matsuoka, Toshiyuki; Ikura, Yoshihiro; Ueda, Makiko; Naruko, Takahiko; Hozumi, Takeshi; Yoshiyama, Minoru

2009-08-01

Previous studies have shown a correlation between coronary artery cross-sectional diameter and left ventricular (LV) mass. However, no studies have examined the correlation between actual coronary artery volume (CAV) and LV mass. In the present study, measurements of CAV by 64-multislice computed tomography (MSCT) were validated and the relationship between CAV and LV mass was investigated. First, coronary artery phantoms consisting of syringes filled with solutions of contrast medium moving at simulated heart rates were scanned by 64-MSCT. Display window settings permitting accurate calculation of small volumes were optimized by evaluating volume-rendered images of the segmented contrast medium at different window settings. Next, 61 patients without significant coronary artery stenosis were scanned by 64-MSCT with the same protocol as for the phantoms. Coronary arteries were segmented on a workstation and the same window settings were applied to the volume-rendered images to calculate total CAV. Significant correlations between total CAV and LV mass (r=0.660, P<0.0001) were found, whereas an inverse relation was present between total CAV per 100 g of LV mass and LV mass. The novel concept of "CAV" for the characterization of coronary arteries may prove useful for future research, particularly on the causes of LV hypertrophy.

Randomized clinical trial assessing whether additional massage treatments for chronic neck pain improve 12- and 26-week outcomes.

PubMed

Cook, Andrea J; Wellman, Robert D; Cherkin, Daniel C; Kahn, Janet R; Sherman, Karen J

2015-10-01

This is the first study to systematically evaluate the value of a longer treatment period for massage. We provide a framework of how to conceptualize an optimal dose in this challenging setting of nonpharmacologic treatments. The aim was to determine the optimal dose of massage for neck pain. Two-phase randomized trial for persons with chronic nonspecific neck pain. Primary randomization to one of five groups receiving 4 weeks of massage (30 minutes 2x/or 3x/wk or 60 minutes 1x, 2x, or 3x/wk). Booster randomization of participants to receive an additional six massages, 60 minutes 1x/wk, or no additional massage. A total of 179 participants from Group Health and the general population of Seattle, WA, USA recruited between June 2010 and August 2011 were included. Primary outcomes self-reported neck-related dysfunction (Neck Disability Index) and pain (0-10 scale) were assessed at baseline, 12, and 26 weeks. Clinically meaningful improvement was defined as greater than or equal to 5-point decrease in dysfunction and greater than or equal to 30% decrease in pain from baseline. Clinically meaningful improvement for each primary outcome with both follow-up times was analyzed using adjusted modified Poisson generalized estimating equations (GEEs). Secondary analyses for the continuous outcomes used linear GEEs. There were no observed differences by primary treatment group at 12 or 26 weeks. Those receiving booster dose had improvements in both dysfunction and pain at 12 weeks (dysfunction: relative risk [RR]=1.56 [1.08-2.25], p=.018; pain: RR=1.25 [0.98-1.61], p=.077), but those were nonsignificant at 26 weeks (dysfunction: RR=1.22 [0.85-1.74]; pain: RR=1.09 [0.82-1.43]). Subgroup analysis by primary and booster treatments found the booster dose only effective among those initially randomized to one of the 60-minute massage groups. "Booster" doses for those initially receiving 60 minutes of massage should be incorporated into future trials of massage for chronic neck pain. Copyright © 2015 Elsevier Inc. All rights reserved.

Helical tomotherapy to LINAC plan conversion utilizing RayStation Fallback planning.

PubMed

Zhang, Xin; Penagaricano, Jose; Narayanasamy, Ganesh; Corry, Peter; Liu, TianXiao; Sanjay, Maraboyina; Paudel, Nava; Morrill, Steven

2017-01-01

RaySearch RayStation Fallback (FB) planning module can generate an equivalent backup radiotherapy treatment plan facilitating treatment on other linear accelerators. FB plans were generated from the RayStation FB module by simulating the original plan target and organ at risk (OAR) dose distribution and delivered in various backup linear accelerators. In this study, helical tomotherapy (HT) backup plans used in Varian TrueBeam linear accelerator were generated with the RayStation FB module. About 30 patients, 10 with lung cancer, 10 with head and neck (HN) cancer, and 10 with prostate cancer, who were treated with HT, were included in this study. Intensity-modulated radiotherapy Fallback plans (FB-IMRT) were generated for all patients, and three-dimensional conformal radiotherapy Fallback plans (FB-3D) were only generated for lung cancer patients. Dosimetric comparison study evaluated FB plans based on dose coverage to 95% of the PTV volume (R 95 ), PTV mean dose (D mean ), Paddick's conformity index (CI), and dose homogeneity index (HI). The evaluation results showed that all IMRT plans were statistically comparable between HT and FB-IMRT plans except that PTV HI was worse in prostate, and PTV R 95 and HI were worse in HN multitarget plans for FB-IMRT plans. For 3D lung cancer plans, only the PTV R 95 was statistically comparable between HT and FB-3D plans, PTV D mean was higher, and CI and HI were worse compared to HT plans. The FB plans using a TrueBeam linear accelerator generally offer better OAR sparing compared to HT plans for all the patients. In this study, all cases of FB-IMRT plans and 9/10 cases of FB-3D plans were clinically acceptable without further modification and optimization once the FB plans were generated. However, the statistical differences between HT and FB-IMRT/3D plans might not be of any clinically significant. One FB-3D plan failed to simulate the original plan without further optimization. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

On the role of the optimization algorithm of RapidArc(®) volumetric modulated arc therapy on plan quality and efficiency.

PubMed

Vanetti, Eugenio; Nicolini, Giorgia; Nord, Janne; Peltola, Jarkko; Clivio, Alessandro; Fogliata, Antonella; Cozzi, Luca

2011-11-01

The RapidArc volumetric modulated arc therapy (VMAT) planning process is based on a core engine, the so-called progressive resolution optimizer (PRO). This is the optimization algorithm used to determine the combination of field shapes, segment weights (with dose rate and gantry speed variations), which best approximate the desired dose distribution in the inverse planning problem. A study was performed to assess the behavior of two versions of PRO. These two versions mostly differ in the way continuous variables describing the modulated arc are sampled into discrete control points, in the planning efficiency and in the presence of some new features. The analysis aimed to assess (i) plan quality, (ii) technical delivery aspects, (iii) agreement between delivery and calculations, and (iv) planning efficiency of the two versions. RapidArc plans were generated for four groups of patients (five patients each): anal canal, advanced lung, head and neck, and multiple brain metastases and were designed to test different levels of planning complexity and anatomical features. Plans from optimization with PRO2 (first generation of RapidArc optimizer) were compared against PRO3 (second generation of the algorithm). Additional plans were optimized with PRO3 using new features: the jaw tracking, the intermediate dose and the air cavity correction options. Results showed that (i) plan quality was generally improved with PRO3 and, although not for all parameters, some of the scored indices showed a macroscopic improvement with PRO3. (ii) PRO3 optimization leads to simpler patterns of the dynamic parameters particularly for dose rate. (iii) No differences were observed between the two algorithms in terms of pretreatment quality assurance measurements and (iv) PRO3 optimization was generally faster, with a time reduction of a factor approximately 3.5 with respect to PRO2. These results indicate that PRO3 is either clinically beneficial or neutral in terms of dosimetric quality while it showed significant advantages in speed and technical aspects.

Comparison of organ-at-risk sparing and plan robustness for spot-scanning proton therapy and volumetric modulated arc photon therapy in head-and-neck cancer

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

Barten, Danique L. J., E-mail: d.barten@vumc.nl; Tol, Jim P.; Dahele, Max

Purpose: Proton radiotherapy for head-and-neck cancer (HNC) aims to improve organ-at-risk (OAR) sparing over photon radiotherapy. However, it may be less robust for setup and range uncertainties. The authors investigated OAR sparing and plan robustness for spot-scanning proton planning techniques and compared these with volumetric modulated arc therapy (VMAT) photon plans. Methods: Ten HNC patients were replanned using two arc VMAT (RapidArc) and spot-scanning proton techniques. OARs to be spared included the contra- and ipsilateral parotid and submandibular glands and individual swallowing muscles. Proton plans were made using Multifield Optimization (MFO, using three, five, and seven fields) and Single-field Optimizationmore » (SFO, using three fields). OAR sparing was evaluated using mean dose to composite salivary glands (Comp{sub Sal}) and composite swallowing muscles (Comp{sub Swal}). Plan robustness was determined for setup and range uncertainties (±3 mm for setup, ±3% HU) evaluating V95% and V107% for clinical target volumes. Results: Averaged over all patients Comp{sub Sal}/Comp{sub Swal} mean doses were lower for the three-field MFO plans (14.6/16.4 Gy) compared to the three-field SFO plans (20.0/23.7 Gy) and VMAT plans (23.0/25.3 Gy). Using more than three fields resulted in differences in OAR sparing of less than 1.5 Gy between plans. SFO plans were significantly more robust than MFO plans. VMAT plans were the most robust. Conclusions: MFO plans had improved OAR sparing but were less robust than SFO and VMAT plans, while SFO plans were more robust than MFO plans but resulted in less OAR sparing. Robustness of the MFO plans did not increase with more fields.« less

Patterns of Disease Recurrence Following Treatment of Oropharyngeal Cancer With Intensity Modulated Radiation Therapy

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

Garden, Adam S., E-mail: agarden@mdanderson.org; Dong, Lei; Morrison, William H.

Purpose: To report mature results of a large cohort of patients diagnosed with squamous cell carcinoma of the oropharynx who were treated with intensity modulated radiation therapy (IMRT). Methods and Materials: The database of patients irradiated at The University of Texas, M.D. Anderson Cancer Center was searched for patients diagnosed with oropharyngeal cancer and treated with IMRT between 2000 and 2007. A retrospective review of outcome data was performed. Results: The cohort consisted of 776 patients. One hundred fifty-nine patients (21%) were current smokers, 279 (36%) former smokers, and 337 (43%) never smokers. T and N categories and American Jointmore » Committee on Cancer group stages were distributed as follows: T1/x, 288 (37%); T2, 288 (37%); T3, 113 (15%); T4, 87 (11%); N0, 88(12%); N1/x, 140 (18%); N2a, 101 (13%); N2b, 269 (35%); N2c, 122 (16%); and N3, 56 (7%); stage I, 18(2%); stage II, 40(5%); stage III, 150(19%); and stage IV, 568(74%). Seventy-one patients (10%) presented with nodes in level IV. Median follow-up was 54 months. The 5-year overall survival, locoregional control, and overall recurrence-free survival rates were 84%, 90%, and 82%, respectively. Primary site recurrence developed in 7% of patients, and neck recurrence with primary site control in 3%. We could only identify 12 patients (2%) who had locoregional recurrence outside the high-dose target volumes. Poorer survival rates were observed in current smokers, patients with larger primary (T) tumors and lower neck disease. Conclusions: Patients with oropharyngeal cancer treated with IMRT have excellent disease control. Locoregional recurrence was uncommon, and most often occurred in the high dose volumes. Parotid sparing was accomplished in nearly all patients without compromising tumor coverage.« less

SU-E-T-657: Quantitative Assessment of Plan Robustness for Helical Tomotherapy for Head and Neck Cancer Radiotherapy

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

Matney, J; Lian, J; Chera, B

2015-06-15

Introduction: Geometric uncertainties in daily patient setup can lead to variations in the planned dose, especially when using highly conformal techniques such as helical Tomotherapy. To account for the potential effect of geometric uncertainty, our clinical practice is to expand critical structures by 3mm expansion into planning risk volumes (PRV). The PRV concept assumes the spatial dose cloud is insensitive to patient positioning. However, no tools currently exist to determine if a Tomotherapy plan is robust to the effects of daily setup variation. We objectively quantified the impact of geometric uncertainties on the 3D doses to critical normal tissues duringmore » helical Tomotherapy. Methods: Using a Matlab-based program created and validated by Accuray (Madison, WI), the planned Tomotherapy delivery sinogram recalculated dose on shifted CT datasets. Ten head and neck patients were selected for analysis. To simulate setup uncertainty, the patient anatomy was shifted ±3mm in the longitudinal, lateral and vertical axes. For each potential shift, the recalculated doses to various critical normal tissues were compared to the doses delivered to the PRV in the original plan Results: 18 shifted scenarios created from Tomotherapy plans for three patients with head and neck cancers were analyzed. For all simulated setup errors, the maximum doses to the brainstem, spinal cord, parotids and cochlea were no greater than 0.6Gy of the respective original PRV maximum. Despite 3mm setup shifts, the minimum dose delivered to 95% of the CTVs and PTVs were always within 0.4Gy of the original plan. Conclusions: For head and neck sites treated with Tomotherapy, the use of a 3mm PRV expansion provide a reasonable estimate of the dosimetric effects of 3mm setup uncertainties. Similarly, target coverage appears minimally effected by a 3mm setup uncertainty. Data from a larger number of patients will be presented. Future work will include other anatomical sites.« less

Dose--effect relationships for femoral fractures after multimodality limb-sparing therapy of soft-tissue sarcomas of the proximal lower extremity.

PubMed

Pak, Daniel; Vineberg, Karen A; Griffith, Kent A; Sabolch, Aaron; Chugh, Rashmi; Ben-Josef, Edgar; Biermann, Janet Sybil; Feng, Mary

2012-07-15

We investigated the clinical and dosimetric predictors for radiation-associated femoral fractures in patients with proximal lower extremity soft tissue sarcomas (STS). We examined 131 patients with proximal lower extremity STS who received limb-sparing surgery and external-beam radiation therapy between 1985 and 2006. Five (4%) patients sustained pathologic femoral fractures. Dosimetric analysis was limited to 4 fracture patients with full three-dimensional dose information, who were compared with 59 nonfracture patients. The mean doses and volumes of bone (V(d)) receiving specified doses (≥30 Gy, 45 Gy, 60 Gy) at the femoral body, femoral neck, intertrochanteric region, and subtrochanteric region were compared. Clinical predictive factors were also evaluated. Of 4 fracture patients in our dosimetric series, there were three femoral neck fractures with a mean dose of 57.6 ± 8.9 Gy, V30 of 14.5 ± 2.3 cc, V45 of 11.8 ± 1.1 cc, and V60 of 7.2 ± 2.2 cc at the femoral neck compared with 22.9 ± 20.8 Gy, 4.8 ± 5.6 cc, 2.5 ± 3.9 cc, and 0.8 ± 2.7 cc, respectively, for nonfracture patients (p < 0.03 for all). The femoral neck fracture rate was higher than at the subtrochanteric region despite lower mean doses at these subregions. All fracture sites received mean doses greater than 40 Gy. Also, with our policy of prophylactic femoral intramedullary nailing for high-risk patients, there was no significant difference in fracture rates between patients with and without periosteal excision. There were no significant differences in age, sex, tumor size, timing of radiation therapy, and use of chemotherapy between fracture and nonfracture patients. These dose-volume toxicity relationships provide RT optimization goals to guide future efforts for reducing pathologic fracture rates. Prophylactic femoral intramedullary nailing may also reduce fracture risk for susceptible patients. Copyright © 2012 Elsevier Inc. All rights reserved.

Elective neck irradiation for nasopharyngeal carcinoma.

PubMed

Wang, C J; Chen, H C; Huang, E Y; Lee, S P

2000-07-01

This study was conducted to evaluate the effectiveness of elective neck irradiation (ENI) for nasopharyngeal carcinoma (NPC), and to analyze factors associated with ENI failure. A radiation port covering the side of a neck without gross nodal metastasis was qualified for evaluation of the effectiveness of ENI. From 1988 through 1992, a total of 261 patients with N0 (130 cases), N1 (91 cases), and N3 (40 cases) NPCs were studied. All patients were irradiated with 60Co teletherapy or 10 MV x-ray to a total dose of 46.8 Gy/26 fractions, followed by a boost treatment to the primary site to a total dose of 64.8 to 75.6 Gy/36-42 fractions. All ENI ports received irradiation to a dose of 46.8 to 60.8 Gy. The duration of follow-up was 6 to 10 years, with a median of 8.1 years. Factors associated with to the risk of ENI failure were analyzed. (1) The overall 5-year actuarial local control rate and actuarial survival rate were 74% and 63%, respectively. (2) Among the 261 cases in which ENI treatment was used, the treatment failed in 12 cases, accounting for a crude ENI failure rate of 5%. The overall 5- and 10-year cumulative risk of ENI failure was 5% and 7%, respectively. (3) Time from the start of treatment to ENI failure ranged from 9 to 66 months, with a median of 17 months. (4) Of the 12 patients for whom EMI failed, 11 (92%) had recurrence in the upper neck, and one in the lower neck. (5) Existence of prior failure at the primary site was the only factor significantly correlated with the risk of ENI failure (p < 0.001). The 5-year cumulative risk of ENI failure for patients with local failure vs. those without was 16% vs. 1% (p < 0.0001). Moderate-dose ENI was highly effective in the control of subclinical disease in the neck for NPC. ENI failure was closely associated with prior failure at the primary site, implying that local primary tumor failure may lead to an increased potential for metastasis to the neck.

Clinical validation and applications for CT-based atlas for contouring the lower cranial nerves for head and neck cancer radiation therapy.

PubMed

Mourad, Waleed F; Young, Brett M; Young, Rebekah; Blakaj, Dukagjin M; Ohri, Nitin; Shourbaji, Rania A; Manolidis, Spiros; Gámez, Mauricio; Kumar, Mahesh; Khorsandi, Azita; Khan, Majid A; Shasha, Daniel; Blakaj, Adriana; Glanzman, Jonathan; Garg, Madhur K; Hu, Kenneth S; Kalnicki, Shalom; Harrison, Louis B

2013-09-01

Radiation induced cranial nerve palsy (RICNP) involving the lower cranial nerves (CNs) is a serious complication of head and neck radiotherapy (RT). Recommendations for delineating the lower CNs on RT planning studies do not exist. The aim of the current study is to develop a standardized methodology for contouring CNs IX-XII, which would help in establishing RT limiting doses for organs at risk (OAR). Using anatomic texts, radiologic data, and guidance from experts in head and neck anatomy, we developed step-by-step instructions for delineating CNs IX-XII on computed tomography (CT) imaging. These structures were then contoured on five consecutive patients who underwent definitive RT for locally-advanced head and neck cancer (LAHNC). RT doses delivered to the lower CNs were calculated. We successfully developed a contouring atlas for CNs IX-XII. The median total dose to the planning target volume (PTV) was 70Gy (range: 66-70Gy). The median CN (IX-XI) and (XII) volumes were 10c.c (range: 8-12c.c) and 8c.c (range: 7-10c.c), respectively. The median V50, V60, V66, and V70 of the CN (IX-XI) and (XII) volumes were (85, 77, 71, 65) and (88, 80, 74, 64) respectively. The median maximal dose to the CN (IX-XI) and (XII) were 72Gy (range: 66-77) and 71Gy (range: 64-78), respectively. We have generated simple instructions for delineating the lower CNs on RT planning imaging. Further analyses to explore the relationship between lower CN dosing and the risk of RICNP are recommended in order to establish limiting doses for these OARs. Published by Elsevier Ltd.

Evaluation of the trade-offs encountered in planning and treating locally advanced head and neck cancer: intensity-modulated radiation therapy vs dual-arc volumetric-modulated arc therapy

PubMed Central

Oliver, M; McConnell, D; Romani, M; McAllister, A; Pearce, A; Andronowski, A; Wang, X; Leszczynski, K

2012-01-01

Objective The primary purpose of this study was to assess the practical trade-offs between intensity-modulated radiation therapy (IMRT) and dual-arc volumetric-modulated arc therapy (DA-VMAT) for locally advanced head and neck cancer (HNC). Methods For 15 locally advanced HNC data sets, nine-field step-and-shoot IMRT plans and two full-rotation DA-VMAT treatment plans were created in the Pinnacle3 v. 9.0 (Philips Medical Systems, Fitchburg, WI) treatment planning environment and then delivered on a Clinac iX (Varian Medical Systems, Palo Alto, CA) to a cylindrical detector array. The treatment planning goals were organised into four groups based on their importance: (1) spinal cord, brainstem, optical structures; (2) planning target volumes; (3) parotids, mandible, larynx and brachial plexus; and (4) normal tissues. Results Compared with IMRT, DA-VMAT plans were of equal plan quality (p>0.05 for each group), able to be delivered in a shorter time (3.1 min vs 8.3 min, p<0.0001), delivered fewer monitor units (on average 28% fewer, p<0.0001) and produced similar delivery accuracy (p>0.05 at γ2%/2mm and γ3%/3mm). However, the VMAT plans took more planning time (28.9 min vs 7.7 min per cycle, p<0.0001) and required more data for a three-dimensional dose (20 times more, p<0.0001). Conclusions Nine-field step-and-shoot IMRT and DA-VMAT are both capable of meeting the majority of planning goals for locally advanced HNC. The main trade-offs between the techniques are shorter treatment time for DA-VMAT but longer planning time and the additional resources required for implementation of a new technology. Based on this study, our clinic has incorporated DA-VMAT for locally advanced HNC. Advances in knowledge DA-VMAT is a suitable alternative to IMRT for locally advanced HNC. PMID:22806619

Dosing study of massage for chronic neck pain: protocol for the dose response evaluation and analysis of massage [DREAM] trial

PubMed Central

2012-01-01

Background Despite the growing popularity of massage, its effectiveness for treating neck pain remains unclear, largely because of the poor quality of research. A major deficiency of previous studies has been their use of low “doses” of massage that massage therapists consider inadequate. Unfortunately, the number of minutes per massage session, sessions per week, or weeks of treatment necessary for massage to have beneficial or optimal effects are not known. This study is designed to address these gaps in our knowledge by determining, for persons with chronic neck pain: 1) the optimal combination of number of treatments per week and length of individual treatment session, and 2) the optimal number of weeks of treatment. Methods/design In this study, 228 persons with chronic non-specific neck pain will be recruited from primary health care clinics in a large health care system in the Seattle area. Participants will be randomized to a wait list control group or 4 weeks of treatment with one of 5 different dosing combinations (2 or 3 30-min treatments per week or 1, 2, or 3 60-min treatments per week). At the end of this 4-week primary treatment period, participants initially receiving each of the 5 dosing combinations will be randomized to a secondary treatment period of either no additional treatment or 6 weekly 60-min massages. The primary outcomes, neck-related dysfunction and pain, will be assessed by blinded telephone interviewers 5, 12, and 26 weeks post-randomization. To better characterize the trajectory of treatment effects, these interview data will be supplemented with outcomes data collected by internet questionnaire at 10, 16, 20 and 39 weeks. Comparisons of outcomes for the 6 groups during the primary treatment period will identify the optimal weekly dose, while comparisons of outcomes during the secondary treatment period will determine if 10 weeks of treatment is superior to 4 weeks. Discussion A broad dosing schedule was included in this trial. If adherence to any of these doses is poor, those doses will be discontinued. Trial registration This trial is registered in ClinicalTrials.gov, with the ID number of NCT01122836 PMID:22985134

[Diagnosis of the scaphoid bone : Fractures, nonunion, circulation, perfusion].

PubMed

Kahl, T; Razny, F K; Benter, J P; Mutig, K; Hegenscheid, K; Mutze, S; Eisenschenk, A

2016-11-01

The clinical relevance of scaphoid bone fractures is reflected by their high incidence, accounting for approximately 60 % among carpal fractures and for 2-3 % of all fractures. With adequate therapy most scaphoid bone fractures heal completely without complications. Insufficient immobilization or undiagnosed fractures increase the risk of nonunion and the development of pseudarthrosis.X-ray examination enables initial diagnosis of scaphoid fracture in 70-80 % of cases. Positive clinical symptoms by negative x‑ray results require further diagnostics by multi-slice spiral CT (MSCT) or MRI to exclude or confirm a fracture. In addition to the diagnosis and description of fractures MSCT is helpful for determining the stage of nonunion. Contrast enhanced MRI is the best method to assess the vitality of scaphoid fragments.

A study to establish reasonable action limits for patient‐specific quality assurance in intensity‐modulated radiation therapy

PubMed Central

Alecu, Ionut M.; Stan, Andrada R.; Alecu, Marius; Ciura, Andrei; Hansen, Jeremy M.; Alecu, Rodica

2007-01-01

An effective patient quality assurance (QA) program for intensity‐modulated radiation therapy (IMRT) requires accurate and realistic plan acceptance criteria—that is, action limits. Based on dose measurements performed with a commercially available two‐dimensional (2D) diode array, we analyzed 747 fluence maps resulting from a routine patient QA program for IMRT plans. The fluence maps were calculated by three different commercially available (ADAC, CMS, Eclipse) treatment planning systems (TPSs) and were delivered using 6‐MV X‐ray beams produced by linear accelerators. To establish reasonably achievable and clinically acceptable limits for the dose deviations, the agreement between the measured and calculated fluence maps was evaluated in terms of percent dose error (PDE) for a few points and percent of passing points (PPP) for the isodose distribution. The analysis was conducted for each TPS used in the study (365 ADAC, 162 CMS, 220 Eclipse), for multiple treatment sites (prostate, pelvis, head and neck, spine, rectum, anus, lung, brain), at the normalization point for 3% percentage difference (%Diff) and 3‐mm distance to agreement (DTA) criteria. We investigated the treatment‐site dependency of PPP and PDE. The results show that, at 3% and 3‐mm criteria, a 95% PPP and 3% PDE can be achieved for prostate treatments and a 90% PPP and 5% PDE are attainable for any treatment site. PACS Numbers: 87.53Dq, 87.53Tf, 87.53Xd, 87.56Fc PMID:17592459

Investigation of the feasibility of elective irradiation to neck level Ib using intensity-modulated radiotherapy for patients with nasopharyngeal carcinoma: a retrospective analysis.

PubMed

Zhang, Fan; Cheng, Yi-Kan; Li, Wen-Fei; Guo, Rui; Chen, Lei; Sun, Ying; Mao, Yan-Ping; Zhou, Guan-Qun; Liu, Xu; Liu, Li-Zhi; Lin, Ai-Hua; Tang, Ling-Long; Ma, Jun

2015-10-15

To assess the feasibility of elective neck irradiation to level Ib in nasopharyngeal carcinoma (NPC) using intensity-modulated radiation therapy (IMRT). We retrospectively analyzed 1438 patients with newly-diagnosed, non-metastatic and biopsy-proven NPC treated with IMRT. Greatest dimension of level IIa LNs (DLN-IIa) ≥ 20 mm and/or level IIa LNs with extracapsular spread (ES), oropharynx involvement and positive bilateral cervical lymph nodes (CLNs) were independently significantly associated with metastasis to level Ib LN at diagnosis. No recurrence at level Ib was observed in the 904 patients without these characteristics (median follow-up, 38.7 months; range, 1.3-57.8 months), these patients were classified as low risk. Level Ib irradiation was not an independent risk factor for locoregional failure-free survival, distant failure-free survival, failure-free survival or overall survival in low risk patients. The frequency of grade ≥ 2 subjective xerostomia at 12 months after radiotherapy was not significantly different between low risk patients who received level Ib-sparing, unilateral level Ib-covering or bilateral level Ib-covering IMRT. Level Ib-sparing IMRT should be safe and feasible for patients without a DLN-IIa ≥ 20 mm and/or level IIa LNs with ES, positive bilateral CLNs or oropharynx involvement at diagnosis. Further investigations based on specific criteria for dose constraints for the submandibular glands are warranted to confirm the benefit of elective level Ib irradiation.

Image quality improvement in megavoltage cone beam CT using an imaging beam line and a sintered pixelated array system

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

Breitbach, Elizabeth K.; Maltz, Jonathan S.; Gangadharan, Bijumon

2011-11-15

Purpose: To quantify the improvement in megavoltage cone beam computed tomography (MVCBCT) image quality enabled by the combination of a 4.2 MV imaging beam line (IBL) with a carbon electron target and a detector system equipped with a novel sintered pixelated array (SPA) of translucent Gd{sub 2}O{sub 2}S ceramic scintillator. Clinical MVCBCT images are traditionally acquired with the same 6 MV treatment beam line (TBL) that is used for cancer treatment, a standard amorphous Si (a-Si) flat panel imager, and the Kodak Lanex Fast-B (LFB) scintillator. The IBL produces a greater fluence of keV-range photons than the TBL, to whichmore » the detector response is more optimal, and the SPA is a more efficient scintillator than the LFB. Methods: A prototype IBL + SPA system was installed on a Siemens Oncor linear accelerator equipped with the MVision{sup TM} image guided radiation therapy (IGRT) system. A SPA strip consisting of four neighboring tiles and measuring 40 cm by 10.96 cm in the crossplane and inplane directions, respectively, was installed in the flat panel imager. Head- and pelvis-sized phantom images were acquired at doses ranging from 3 to 60 cGy with three MVCBCT configurations: TBL + LFB, IBL + LFB, and IBL + SPA. Phantom image quality at each dose was quantified using the contrast-to-noise ratio (CNR) and modulation transfer function (MTF) metrics. Head and neck, thoracic, and pelvic (prostate) cancer patients were imaged with the three imaging system configurations at multiple doses ranging from 3 to 15 cGy. The systems were assessed qualitatively from the patient image data. Results: For head and neck and pelvis-sized phantom images, imaging doses of 3 cGy or greater, and relative electron densities of 1.09 and 1.48, the CNR average improvement factors for imaging system change of TBL + LFB to IBL + LFB, IBL + LFB to IBL + SPA, and TBL + LFB to IBL + SPA were 1.63 (p < 10{sup -8}), 1.64 (p < 10{sup -13}), 2.66 (p < 10{sup -9}), respectively. For all imaging doses, soft tissue contrast was more easily differentiated on IBL + SPA head and neck and pelvic images than TBL + LFB and IBL + LFB. IBL + SPA thoracic images were comparable to IBL + LFB images, but less noisy than TBL + LFB images at all imaging doses considered. The mean MTFs over all imaging doses were comparable, at within 3%, for all imaging system configurations for both the head- and pelvis-sized phantoms. Conclusions: Since CNR scales with the square root of imaging dose, changing from TBL + LFB to IBL + LFB and IBL + LFB to IBL + SPA reduces the imaging dose required to obtain a given CNR by factors of 0.38 and 0.37, respectively. MTFs were comparable between imaging system configurations. IBL + SPA patient image quality was always better than that of the TBL + LFB system and as good as or better than that of the IBL + LFB system, for a given dose.« less

Verification of eye lens dose in IMRT by MOSFET measurement.

PubMed

Wang, Xuetao; Li, Guangjun; Zhao, Jianling; Song, Ying; Xiao, Jianghong; Bai, Sen

2018-04-17

The eye lens is recognized as one of the most radiosensitive structures in the human body. The widespread use of intensity-modulated radiotherapy (IMRT) complicates dose verification and necessitates high standards of dose computation. The purpose of this work was to assess the computed dose accuracy of eye lens through measurements using a metal-oxide-semiconductor field-effect transistor (MOSFET) dosimetry system. Sixteen clinical IMRT plans of head and neck patients were copied to an anthropomorphic head phantom. Measurements were performed using the MOSFET dosimetry system based on the head phantom. Two MOSFET detectors were imbedded in the eyes of the head phantom as the left and the right lens, covered by approximately 5-mm-thick paraffin wax. The measurement results were compared with the calculated values with a dose grid size of 1 mm. Sixteen IMRT plans were delivered, and 32 measured lens doses were obtained for analysis. The MOSFET dosimetry system can be used to verify the lens dose, and our measurements showed that the treatment planning system used in our clinic can provide adequate dose assessment in eye lenses. The average discrepancy between measurement and calculation was 6.7 ± 3.4%, and the largest discrepancy was 14.3%, which met the acceptability criterion set by the American Association of Physicists in Medicine Task Group 53 for external beam calculation for multileaf collimator-shaped fields in buildup regions. Copyright © 2018 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

A multiscale filter for noise reduction of low-dose cone beam projections.

PubMed

Yao, Weiguang; Farr, Jonathan B

2015-08-21

The Poisson or compound Poisson process governs the randomness of photon fluence in cone beam computed tomography (CBCT) imaging systems. The probability density function depends on the mean (noiseless) of the fluence at a certain detector. This dependence indicates the natural requirement of multiscale filters to smooth noise while preserving structures of the imaged object on the low-dose cone beam projection. In this work, we used a Gaussian filter, exp(-x2/2σ(2)(f)) as the multiscale filter to de-noise the low-dose cone beam projections. We analytically obtained the expression of σ(f), which represents the scale of the filter, by minimizing local noise-to-signal ratio. We analytically derived the variance of residual noise from the Poisson or compound Poisson processes after Gaussian filtering. From the derived analytical form of the variance of residual noise, optimal σ(2)(f)) is proved to be proportional to the noiseless fluence and modulated by local structure strength expressed as the linear fitting error of the structure. A strategy was used to obtain the reliable linear fitting error: smoothing the projection along the longitudinal direction to calculate the linear fitting error along the lateral direction and vice versa. The performance of our multiscale filter was examined on low-dose cone beam projections of a Catphan phantom and a head-and-neck patient. After performing the filter on the Catphan phantom projections scanned with pulse time 4 ms, the number of visible line pairs was similar to that scanned with 16 ms, and the contrast-to-noise ratio of the inserts was higher than that scanned with 16 ms about 64% in average. For the simulated head-and-neck patient projections with pulse time 4 ms, the visibility of soft tissue structures in the patient was comparable to that scanned with 20 ms. The image processing took less than 0.5 s per projection with 1024   ×   768 pixels.

MEASUREMENT OF RADIATION DOSES TO THE EYE LENS DURING ORTHOPEDIC SURGERY USING AN C-ARM X-RAY SYSTEM.

PubMed

Suzuki, Akira; Matsubara, Kosuke; Sasa, Yuko

2018-04-01

The present study aimed to determine doses delivered to the eye lenses of surgeons while using the inverted-C-arm technique and the protective effect of leaded spectacles during orthopedic surgery. The kerma in air was measured at five positions on leaded glasses positioned near the eye lens and on the neck using small optically stimulated luminescence (OSL) dosemeters. The lens equivalent dose was also measured at the neck using an OSL dosemeter. The maximum equivalent dose to the eye lens and the maximum kerma were 0.8 mSv/month and 0.66 mGy/month, respectively. The leaded glasses reduced the exposure by ~60%. Even if the surgeons are exposed to the maximum dose of X-ray radiation for 5 years, the equivalent doses to the eye lens will not exceed the present limit recommended by the ICRP.

In vivo dosimetry for external photon treatments of head and neck cancers by diodes and TLDS.

PubMed

Tung, C J; Wang, H C; Lo, S H; Wu, J M; Wang, C J

2004-01-01

In vivo dosimetry was implemented for treatments of head and neck cancers in the large fields. Diode and thermoluminescence dosemeter (TLD) measurements were carried out for the linear accelerators of 6 MV photon beams. ESTRO in vivo dosimetry protocols were followed in the determination of midline doses from measurements of entrance and exit doses. Of the fields monitored by diodes, the maximum absolute deviation of measured midline doses from planned target doses was 8%, with the mean value and the standard deviation of -1.0 and 2.7%. If planned target doses were calculated using radiological water equivalent thicknesses rather than patient geometric thicknesses, the maximum absolute deviation dropped to 4%, with the mean and the standard deviation of 0.7 and 1.8%. For in vivo dosimetry monitored by TLDs, the shift in mean dose remained small but the statistical precision became poor.

SU-F-19A-10: Recalculation and Reporting Clinical HDR 192-Ir Head and Neck Dose Distributions Using Model Based Dose Calculation

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

Carlsson Tedgren, A; Persson, M; Nilsson, J

Purpose: To retrospectively re-calculate dose distributions for selected head and neck cancer patients, earlier treated with HDR 192Ir brachytherapy, using Monte Carlo (MC) simulations and compare results to distributions from the planning system derived using TG43 formalism. To study differences between dose to medium (as obtained with the MC code) and dose to water in medium as obtained through (1) ratios of stopping powers and (2) ratios of mass energy absorption coefficients between water and medium. Methods: The MC code Algebra was used to calculate dose distributions according to earlier actual treatment plans using anonymized plan data and CT imagesmore » in DICOM format. Ratios of stopping power and mass energy absorption coefficients for water with various media obtained from 192-Ir spectra were used in toggling between dose to water and dose to media. Results: Differences between initial planned TG43 dose distributions and the doses to media calculated by MC are insignificant in the target volume. Differences are moderate (within 4–5 % at distances of 3–4 cm) but increase with distance and are most notable in bone and at the patient surface. Differences between dose to water and dose to medium are within 1-2% when using mass energy absorption coefficients to toggle between the two quantities but increase to above 10% for bone using stopping power ratios. Conclusion: MC predicts target doses for head and neck cancer patients in close agreement with TG43. MC yields improved dose estimations outside the target where a larger fraction of dose is from scattered photons. It is important with awareness and a clear reporting of absorbed dose values in using model based algorithms. Differences in bone media can exceed 10% depending on how dose to water in medium is defined.« less

Analysis of Factors Influencing the Development of Xerostomia during Intensity-Modulated Radiotherapy

PubMed Central

Randall, Ken; Stevens, Jason; Yepes, Juan Fernando; Randall, Marcus E.; Kudrimoti, Mahesh; Feddock, Jonathan; Xi, Jing; Kryscio, Richard J.; Miller, Craig S.

2013-01-01

OBJECTIVES Factors influencing xerostomia during intensity-modulated radiation therapy (IMRT) were assessed. METHODS A 6-week study of 32 head and neck cancer (HNC) patients was performed. Subjects completed the Xerostomia Inventory (XI) and provided stimulated saliva (SS) at baseline, week two and at end of IMRT. Influence of SS flow rate (SSFR), calcium and mucin 5b (MUC5b) concentrations and radiation dose on xerostomia was determined. RESULTS HNC subjects experienced mean SSFR decline of 36% by visit two (N=27; p=0.012) and 57% by visit three (N=20; p=0.0004), Concentrations of calcium and MUC5b increased, but not significantly during IMRT (p>0.05). Xerostomia correlated most with decreasing salivary flow rate as determined by Spearman correlations (p<0.04) and linear mixed models (p<0.0001). CONCLUSIONS Although IMRT is sparing to the parotid glands, it has an early effect on SSFR and the constituents in saliva in a manner that is associated with the perception of xerostomia. PMID:23523462

SU-E-J-122: The CBCT Dose Calculation Using a Patient Specific CBCT Number to Mass Density Conversion Curve Based On a Novel Image Registration and Organ Mapping Method in Head-And-Neck Radiation Therapy

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

Zhou, J; Lasio, G; Chen, S

2015-06-15

Purpose: To develop a CBCT HU correction method using a patient specific HU to mass density conversion curve based on a novel image registration and organ mapping method for head-and-neck radiation therapy. Methods: There are three steps to generate a patient specific CBCT HU to mass density conversion curve. First, we developed a novel robust image registration method based on sparseness analysis to register the planning CT (PCT) and the CBCT. Second, a novel organ mapping method was developed to transfer the organs at risk (OAR) contours from the PCT to the CBCT and corresponding mean HU values of eachmore » OAR were measured in both the PCT and CBCT volumes. Third, a set of PCT and CBCT HU to mass density conversion curves were created based on the mean HU values of OARs and the corresponding mass density of the OAR in the PCT. Then, we compared our proposed conversion curve with the traditional Catphan phantom based CBCT HU to mass density calibration curve. Both curves were input into the treatment planning system (TPS) for dose calculation. Last, the PTV and OAR doses, DVH and dose distributions of CBCT plans are compared to the original treatment plan. Results: One head-and-neck cases which contained a pair of PCT and CBCT was used. The dose differences between the PCT and CBCT plans using the proposed method are −1.33% for the mean PTV, 0.06% for PTV D95%, and −0.56% for the left neck. The dose differences between plans of PCT and CBCT corrected using the CATPhan based method are −4.39% for mean PTV, 4.07% for PTV D95%, and −2.01% for the left neck. Conclusion: The proposed CBCT HU correction method achieves better agreement with the original treatment plan compared to the traditional CATPhan based calibration method.« less

Cervical lymph node metastases from unknown primary cancer: a single-institution experience with intensity-modulated radiotherapy.

PubMed

Villeneuve, Hugo; Després, Philippe; Fortin, Bernard; Filion, Edith; Donath, David; Soulières, Denis; Guertin, Louis; Ayad, Tarek; Christopoulos, Apostolos; Nguyen-Tan, Phuc Felix

2012-04-01

To determine the effectiveness and rate of complications of intensity-modulated radiotherapy (IMRT) in the treatment of cervical lymph node metastases from unknown primary cancer. Between February 2005 and November 2008, 25 patients with an unknown primary cancer underwent IMRT, with a median radiation dose of 70 Gy. The bilateral neck and ipsilateral putative pharyngeal mucosa were included in the target volume. All patients had squamous cell carcinoma, except for 1 patient who had adenosquamous differentiation. They were all treated with curative intent. Of the 25 included patients, 20 were men and 5 were women, with a median age of 54 years. Of these patients, 3 had Stage III, 18 had Stage IVa, and 4 had Stage IVb. Of the 25 patients, 18 (72%) received platinum-based chemotherapy in a combined-modality setting. Neck dissection was reserved for residual disease after definitive IMRT. Overall survival, disease-free survival, and locoregional control were calculated using the Kaplan-Meier method. With a median follow-up of 38 months, the overall survival, disease-free survival, and locoregional control rates were all 100% at 3 years. No occurrence of primary cancer was observed during the follow-up period. The reported rates of xerostomia reduced with the interval from the completion of treatment. Nine patients (36%) reported Grade 2 or greater xerostomia at 6 months, and only 2 (8%) of them reported the same grade of salivary function toxicity after 24 months of follow-up. In our institution, IMRT for unknown primary cancer has provided good overall and disease-free survival in all the patients with an acceptable rate of complications. IMRT allowed us to address the bilateral neck and ipsilateral putative pharyngeal mucosa with minimal late salivary function toxicity. The use of concurrent chemotherapy and IMRT for more advanced disease led to good clinical results with reasonable toxicities. Copyright © 2012 Elsevier Inc. All rights reserved.

Comparison of anatomy-based, fluence-based and aperture-based treatment planning approaches for VMAT

NASA Astrophysics Data System (ADS)

Rao, Min; Cao, Daliang; Chen, Fan; Ye, Jinsong; Mehta, Vivek; Wong, Tony; Shepard, David

2010-11-01

Volumetric modulated arc therapy (VMAT) has the potential to reduce treatment times while producing comparable or improved dose distributions relative to fixed-field intensity-modulated radiation therapy. In order to take full advantage of the VMAT delivery technique, one must select a robust inverse planning tool. The purpose of this study was to evaluate the effectiveness and efficiency of VMAT planning techniques of three categories: anatomy-based, fluence-based and aperture-based inverse planning. We have compared these techniques in terms of the plan quality, planning efficiency and delivery efficiency. Fourteen patients were selected for this study including six head-and-neck (HN) cases, and two cases each of prostate, pancreas, lung and partial brain. For each case, three VMAT plans were created. The first VMAT plan was generated based on the anatomical geometry. In the Elekta ERGO++ treatment planning system (TPS), segments were generated based on the beam's eye view (BEV) of the target and the organs at risk. The segment shapes were then exported to Pinnacle3 TPS followed by segment weight optimization and final dose calculation. The second VMAT plan was generated by converting optimized fluence maps (calculated by the Pinnacle3 TPS) into deliverable arcs using an in-house arc sequencer. The third VMAT plan was generated using the Pinnacle3 SmartArc IMRT module which is an aperture-based optimization method. All VMAT plans were delivered using an Elekta Synergy linear accelerator and the plan comparisons were made in terms of plan quality and delivery efficiency. The results show that for cases of little or modest complexity such as prostate, pancreas, lung and brain, the anatomy-based approach provides similar target coverage and critical structure sparing, but less conformal dose distributions as compared to the other two approaches. For more complex HN cases, the anatomy-based approach is not able to provide clinically acceptable VMAT plans while highly conformal dose distributions were obtained using both aperture-based and fluence-based inverse planning techniques. The aperture-based approach provides improved dose conformity than the fluence-based technique in complex cases.

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

Caudell, Jimmy J.; Schaner, Philip E.; Meredith, Ruby F.

Purpose: The use of altered fractionation radiotherapy (RT) regimens, as well as concomitant chemotherapy and RT, to intensify therapy for locally advanced head-and-neck cancer can lead to increased rates of long-term dysphagia. Methods and Materials: We identified 122 patients who had undergone definitive RT for locally advanced head-and-neck cancer, after excluding those who had been treated for a second or recurrent head-and-neck primary, had Stage I-II disease, developed locoregional recurrence, had <12 months of follow-up, or had undergone postoperative RT. The patient, tumor, and treatment factors were correlated with a composite of 3 objective endpoints as a surrogate for severemore » long-term dysphagia: percutaneous endoscopic gastrostomy tube dependence at the last follow-up visit; aspiration on a modified barium swallow study or a clinical diagnosis of aspiration pneumonia; or the presence of a pharyngoesophageal stricture. Results: A composite dysphagia outcome occurred in 38.5% of patients. On univariate analysis, the primary site (p = 0.01), use of concurrent chemotherapy (p = 0.01), RT schedule (p = 0.02), and increasing age (p = 0.04) were significantly associated with development of composite long-term dysphagia. The use of concurrent chemotherapy (p = 0.01), primary site (p = 0.02), and increasing age (p = 0.02) remained significant on multivariate analysis. Conclusion: The addition of concurrent chemotherapy to RT for locally advanced head-and-neck cancer resulted in increased long-term dysphagia. Early intervention using swallowing exercises, avoidance of nothing-by-mouth periods, and the use of intensity-modulated RT to reduce the dose to the uninvolved swallowing structures should be explored further in populations at greater risk of long-term dysphagia.« less

Therapeutic Exercise Training to Reduce Chronic Headache in Working Women: Design of a Randomized Controlled Trial.

PubMed

Rinne, Marjo; Garam, Sanna; Häkkinen, Arja; Ylinen, Jari; Kukkonen-Harjula, Katriina; Nikander, Riku

2016-05-01

Cervicogenic headache and migraine are common causes of visits to physicians and physical therapists. Few randomized trials utilizing active physical therapy and progressive therapeutic exercise have been previously published. The existing evidence on active treatment methods supports a moderate effect on cervicogenic headache. The aim of this study is to investigate whether a progressive, group-based therapeutic exercise program decreases the intensity and frequency of chronic headache among women compared with a control group receiving a sham dose of transcutaneous electrical nerve stimulation (TENS) and stretching exercises. A randomized controlled trial with 6-month intervention and follow-up was developed. The participants were randomly assigned to either a treatment group or a control group. The study is being conducted at 2 study centers. The participants are women aged 18 to 60 years with chronic cervicogenic headache or migraine. The treatment group's exercise program consisted of 6 progressive therapeutic exercise modules, including proprioceptive low-load progressive craniocervical and cervical exercises and high-load exercises for the neck muscles. The participants in the control group received 6 individually performed sham TENS treatment sessions. The primary outcome is the intensity of headache. The secondary outcomes are changes in frequency and duration of headache, neck muscle strength, neck and shoulder flexibility, impact of headache on daily life, neck disability, fear-avoidance beliefs, work ability, and quality of life. Between-group differences will be analyzed separately at 6, 12, and 24 months with generalized linear mixed models. In the case of count data (eg, frequency of headache), Poisson or negative binomial regression will be used. The therapists are not blinded. The effects of specific therapeutic exercises on frequency, intensity, and duration of chronic headache and migraine will be reported. © 2016 American Physical Therapy Association.

Clinical trials for treating recurrent head and neck cancer with boron neutron capture therapy using the Tsing-Hua Open Pool Reactor.

PubMed

Wang, Ling-Wei; Liu, Yen-Wan Hsueh; Chou, Fong-In; Jiang, Shiang-Huei

2018-06-19

Head and neck (HN) cancer is an endemic disease in Taiwan, China. Locally recurrent HN cancer after full-dose irradiation poses a therapeutic challenge, and boron neutron capture therapy (BNCT) may be a solution that could provide durable local control with tolerable toxicity. The Tsing-Hua Open Pool Reactor (THOR) at National Tsing-Hua University in Hsin-Chu, provides a high-quality epithermal neutron source for basic and clinical BNCT research. Our first clinical trial, entitled "A phase I/II trial of boron neutron capture therapy for recurrent head and neck cancer at THOR", was carried out between 2010 and 2013. A total of 17 patients with 23 recurrent HN tumors who had received high-dose photon irradiation were enrolled in the study. The fructose complex of L-boronophenylalanine was used as a boron carrier, and a two-fraction BNCT treatment regimen at 28-day intervals was used for each patient. Toxicity was acceptable, and although the response rate was high (12/17), re-recurrence within or near the radiation site was common. To obtain better local control, another clinical trial entitled "A phase I/II trial of boron neutron capture therapy combined with image-guided intensity-modulated radiotherapy (IG-IMRT) for locally recurrent HN cancer" was initiated in 2014. The first administration of BNCT was performed according to our previous protocol, and IG-IMRT was initiated 28 days after BNCT. As of May 2017, seven patients have been treated with this combination. The treatment-related toxicity was similar to that previously observed with two BNCT applications. Three patients had a complete response, but locoregional recurrence was the major cause of failure despite initially good responses. Future clinical trials combining BNCT with other local or systemic treatments will be carried out for recurrent HN cancer patients at THOR.

Quality of Intensity Modulated Radiation Therapy Treatment Plans Using a {sup 60}Co Magnetic Resonance Image Guidance Radiation Therapy System

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

Wooten, H. Omar, E-mail: hwooten@radonc.wustl.edu; Green, Olga; Yang, Min

2015-07-15

Purpose: This work describes a commercial treatment planning system, its technical features, and its capabilities for creating {sup 60}Co intensity modulated radiation therapy (IMRT) treatment plans for a magnetic resonance image guidance radiation therapy (MR-IGRT) system. Methods and Materials: The ViewRay treatment planning system (Oakwood Village, OH) was used to create {sup 60}Co IMRT treatment plans for 33 cancer patients with disease in the abdominal, pelvic, thorax, and head and neck regions using physician-specified patient-specific target coverage and organ at risk (OAR) objectives. Backup plans using a third-party linear accelerator (linac)-based planning system were also created. Plans were evaluated bymore » attending physicians and approved for treatment. The {sup 60}Co and linac plans were compared by evaluating conformity numbers (CN) with 100% and 95% of prescription reference doses and heterogeneity indices (HI) for planning target volumes (PTVs) and maximum, mean, and dose-volume histogram (DVH) values for OARs. Results: All {sup 60}Co IMRT plans achieved PTV coverage and OAR sparing that were similar to linac plans. PTV conformity for {sup 60}Co was within <1% and 3% of linac plans for 100% and 95% prescription reference isodoses, respectively, and heterogeneity was on average 4% greater. Comparisons of OAR mean dose showed generally better sparing with linac plans in the low-dose range <20 Gy, but comparable sparing for organs with mean doses >20 Gy. The mean doses for all {sup 60}Co plan OARs were within clinical tolerances. Conclusions: A commercial {sup 60}Co MR-IGRT device can produce highly conformal IMRT treatment plans similar in quality to linac IMRT for a variety of disease sites. Additional work is in progress to evaluate the clinical benefit of other novel features of this MR-IGRT system.« less

SU-F-T-320: Assessing Placement Error of Optically Stimulated Luminescent in Vivo Dosimeters Using Cone-Beam Computed Tomography

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

Riegel, A; Klein, E; Tariq, M

Purpose: Optically-stimulated luminescent dosimeters (OSLDs) are increasingly utilized for in vivo dosimetry of complex radiation delivery techniques such as intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT). Evaluation of clinical uncertainties such as placement error has not been performed. This work retrospectively investigates the magnitude of placement error using conebeam computed tomography (CBCT) and its effect on measured/planned dose agreement. Methods: Each OSLD was placed at a physicist-designated location on the patient surface on a weekly basis. The location was given in terms of a gantry angle and two-dimensional offset from central axis. The OSLDs were placed before dailymore » image guidance. We identified 77 CBCTs from 25 head-and-neck patients who received IMRT or VMAT, where OSLDs were visible on the CT image. Grossly misplaced OSLDs were excluded (e.g. wrong laterality). CBCTs were registered with the treatment plan and the distance between the planned and actual OSLD location was calculated in two dimensions in the beam’s eye view. Distances were correlated with measured/planned dose percent differences. Results: OSLDs were grossly misplaced for 5 CBCTs (6.4%). For the remaining 72 CBCTs, average placement error was 7.0±6.0 mm. These errors were not correlated with measured/planned dose percent differences (R{sup 2}=0.0153). Generalizing the dosimetric effect of placement errors may be unreliable. Conclusion: Correct placement of OSLDs for IMRT and VMAT treatments is critical to accurate and precise in vivo dosimetry. Small placement errors could produce large disagreement between measured and planned dose. Further work includes expansion to other treatment sites, examination of planned dose at the actual point of OSLD placement, and the influence of imageguided shifts on measured/planned dose agreement.« less

Radiation Therapy Planning for Early-Stage Hodgkin Lymphoma: Experience of the International Lymphoma Radiation Oncology Group

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

Maraldo, Maja V., E-mail: dra.maraldo@gmail.com; Dabaja, Bouthaina S.; Filippi, Andrea R.

Purpose: Early-stage Hodgkin lymphoma (HL) is a rare disease, and the location of lymphoma varies considerably between patients. Here, we evaluate the variability of radiation therapy (RT) plans among 5 International Lymphoma Radiation Oncology Group (ILROG) centers with regard to beam arrangements, planning parameters, and estimated doses to the critical organs at risk (OARs). Methods: Ten patients with stage I-II classic HL with masses of different sizes and locations were selected. On the basis of the clinical information, 5 ILROG centers were asked to create RT plans to a prescribed dose of 30.6 Gy. A postchemotherapy computed tomography scan with precontouredmore » clinical target volume (CTV) and OARs was provided for each patient. The treatment technique and planning methods were chosen according to each center's best practice in 2013. Results: Seven patients had mediastinal disease, 2 had axillary disease, and 1 had disease in the neck only. The median age at diagnosis was 34 years (range, 21-74 years), and 5 patients were male. Of the resulting 50 treatment plans, 15 were planned with volumetric modulated arc therapy (1-4 arcs), 16 with intensity modulated RT (3-9 fields), and 19 with 3-dimensional conformal RT (2-4 fields). The variations in CTV-to-planning target volume margins (5-15 mm), maximum tolerated dose (31.4-40 Gy), and plan conformity (conformity index 0-3.6) were significant. However, estimated doses to OARs were comparable between centers for each patient. Conclusions: RT planning for HL is challenging because of the heterogeneity in size and location of disease and, additionally, to the variation in choice of treatment techniques and field arrangements. Adopting ILROG guidelines and implementing universal dose objectives could further standardize treatment techniques and contribute to lowering the dose to the surrounding OARs.« less

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

Wan Chan Tseung, Hok Seum, E-mail: wanchantseung.hok@mayo.edu; Ma, Jiasen; Kreofsky, Cole R.

Purpose: Our aim is to demonstrate the feasibility of fast Monte Carlo (MC)–based inverse biological planning for the treatment of head and neck tumors in spot-scanning proton therapy. Methods and Materials: Recently, a fast and accurate graphics processor unit (GPU)–based MC simulation of proton transport was developed and used as the dose-calculation engine in a GPU-accelerated intensity modulated proton therapy (IMPT) optimizer. Besides dose, the MC can simultaneously score the dose-averaged linear energy transfer (LET{sub d}), which makes biological dose (BD) optimization possible. To convert from LET{sub d} to BD, a simple linear relation was assumed. By use of thismore » novel optimizer, inverse biological planning was applied to 4 patients, including 2 small and 1 large thyroid tumor targets, as well as 1 glioma case. To create these plans, constraints were placed to maintain the physical dose (PD) within 1.25 times the prescription while maximizing target BD. For comparison, conventional intensity modulated radiation therapy (IMRT) and IMPT plans were also created using Eclipse (Varian Medical Systems) in each case. The same critical-structure PD constraints were used for the IMRT, IMPT, and biologically optimized plans. The BD distributions for the IMPT plans were obtained through MC recalculations. Results: Compared with standard IMPT, the biologically optimal plans for patients with small tumor targets displayed a BD escalation that was around twice the PD increase. Dose sparing to critical structures was improved compared with both IMRT and IMPT. No significant BD increase could be achieved for the large thyroid tumor case and when the presence of critical structures mitigated the contribution of additional fields. The calculation of the biologically optimized plans can be completed in a clinically viable time (<30 minutes) on a small 24-GPU system. Conclusions: By exploiting GPU acceleration, MC-based, biologically optimized plans were created for small–tumor target patients. This optimizer will be used in an upcoming feasibility trial on LET{sub d} painting for radioresistant tumors.« less

A new metric for assessing IMRT modulation complexity and plan deliverability.

PubMed

McNiven, Andrea L; Sharpe, Michael B; Purdie, Thomas G

2010-02-01

To evaluate the utility of a new complexity metric, the modulation complexity score (MCS), in the treatment planning and quality assurance processes and to evaluate the relationship of the metric with deliverability. A multisite (breast, rectum, prostate, prostate bed, lung, and head and neck) and site-specific (lung) dosimetric evaluation has been completed. The MCS was calculated for each beam and the overall treatment plan. A 2D diode array (MapCHECK, Sun Nuclear, Melbourne, FL) was used to acquire measurements for each beam. The measured and planned dose (PINNACLE3, Phillips, Madison, WI) was evaluated using different percent differences and distance to agreement (DTA) criteria (3%/ 3 mm and 2%/ 1 mm) and the relationship between the dosimetric results and complexity (as measured by the MCS or simple beam parameters) assessed. For the multisite analysis (243 plans total), the mean MCS scores for each treatment site were breast (0.92), rectum (0.858), prostate (0.837), prostate bed (0.652), lung (0.631), and head and neck (0.356). The MCS allowed for compilation of treatment site-specific statistics, which is useful for comparing different techniques, as well as for comparison of individual treatment plans with the typical complexity levels. For the six plans selected for dosimetry, the average diode percent pass rate was 98.7% (minimum of 96%) for 3%/3 mm evaluation criteria. The average difference in absolute dose measurement between the planned and measured dose was 1.7 cGy. The detailed lung analysis also showed excellent agreement between the measured and planned dose, as all beams had a diode percentage pass rate for 3%/3 mm criteria of greater than 95.9%, with an average pass rate of 99.0%. The average absolute maximum dose difference for the lung plans was 0.7 cGy. There was no direct correlation between the MCS and simple beam parameters which could be used as a surrogate for complexity level (i.e., number of segments or MU). An evaluation criterion of 2%/ 1 mm reliably allowed for the identification of beams that are dosimetrically robust. In this study we defined a robust beam or plan as one that maintained a diode percentage pass rate greater than 90% at 2%/ 1 mm, indicating delivery that was deemed accurate when compared to the planned dose, even under stricter evaluation criterion. MCS and MU threshold criteria were determined by defining a required specificity of 1.0. A MCS threshold of 0.8 allowed for identification of robust deliverability with a sensitivity of 0.36. In contrast, MU had a lower sensitivity of 0.23 for a threshold of 50 MU. The MCS allows for a quantitative assessment of plan complexity, on a fixed scale, that can be applied to all treatment sites and can provide more information related to dose delivery than simple beam parameters. This could prove useful throughout the entire treatment planning and QA process.

Experience-based quality control of clinical intensity-modulated radiotherapy planning.

PubMed

Moore, Kevin L; Brame, R Scott; Low, Daniel A; Mutic, Sasa

2011-10-01

To incorporate a quality control tool, according to previous planning experience and patient-specific anatomic information, into the intensity-modulated radiotherapy (IMRT) plan generation process and to determine whether the tool improved treatment plan quality. A retrospective study of 42 IMRT plans demonstrated a correlation between the fraction of organs at risk (OARs) overlapping the planning target volume and the mean dose. This yielded a model, predicted dose = prescription dose (0.2 + 0.8 [1 - exp(-3 overlapping planning target volume/volume of OAR)]), that predicted the achievable mean doses according to the planning target volume overlap/volume of OAR and the prescription dose. The model was incorporated into the planning process by way of a user-executable script that reported the predicted dose for any OAR. The script was introduced to clinicians engaged in IMRT planning and deployed thereafter. The script's effect was evaluated by tracking δ = (mean dose-predicted dose)/predicted dose, the fraction by which the mean dose exceeded the model. All OARs under investigation (rectum and bladder in prostate cancer; parotid glands, esophagus, and larynx in head-and-neck cancer) exhibited both smaller δ and reduced variability after script implementation. These effects were substantial for the parotid glands, for which the previous δ = 0.28 ± 0.24 was reduced to δ = 0.13 ± 0.10. The clinical relevance was most evident in the subset of cases in which the parotid glands were potentially salvageable (predicted dose <30 Gy). Before script implementation, an average of 30.1 Gy was delivered to the salvageable cases, with an average predicted dose of 20.3 Gy. After implementation, an average of 18.7 Gy was delivered to salvageable cases, with an average predicted dose of 17.2 Gy. In the prostate cases, the rectum model excess was reduced from δ = 0.28 ± 0.20 to δ = 0.07 ± 0.15. On surveying dosimetrists at the end of the study, most reported that the script both improved their IMRT planning (8 of 10) and increased their efficiency (6 of 10). This tool proved successful in increasing normal tissue sparing and reducing interclinician variability, providing effective quality control of the IMRT plan development process. Copyright © 2011 Elsevier Inc. All rights reserved.

Evaluation of the optimal combinations of modulation factor and pitch for Helical TomoTherapy plans made with TomoEdge using Pareto optimal fronts.

PubMed

De Kerf, Geert; Van Gestel, Dirk; Mommaerts, Lobke; Van den Weyngaert, Danielle; Verellen, Dirk

2015-09-17

Modulation factor (MF) and pitch have an impact on Helical TomoTherapy (HT) plan quality and HT users mostly use vendor-recommended settings. This study analyses the effect of these two parameters on both plan quality and treatment time for plans made with TomoEdge planning software by using the concept of Pareto optimal fronts. More than 450 plans with different combinations of pitch [0.10-0.50] and MF [1.2-3.0] were produced. These HT plans, with a field width (FW) of 5 cm, were created for five head and neck patients and homogeneity index, conformity index, dose-near-maximum (D2), and dose-near-minimum (D98) were analysed for the planning target volumes, as well as the mean dose and D2 for most critical organs at risk. For every dose metric the median value will be plotted against treatment time. A Pareto-like method is used in the analysis which will show how pitch and MF influence both treatment time and plan quality. For small pitches (≤0.20), MF does not influence treatment time. The contrary is true for larger pitches (≥0.25) as lowering MF will both decrease treatment time and plan quality until maximum gantry speed is reached. At this moment, treatment time is saturated and only plan quality will further decrease. The Pareto front analysis showed optimal combinations of pitch [0.23-0.45] and MF > 2.0 for a FW of 5 cm. Outside this range, plans will become less optimal. As the vendor-recommended settings fall within this range, the use of these settings is validated.

Ultrafast treatment plan optimization for volumetric modulated arc therapy (VMAT)

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

Men Chunhua; Romeijn, H. Edwin; Jia Xun

2010-11-15

Purpose: To develop a novel aperture-based algorithm for volumetric modulated arc therapy (VMAT) treatment plan optimization with high quality and high efficiency. Methods: The VMAT optimization problem is formulated as a large-scale convex programming problem solved by a column generation approach. The authors consider a cost function consisting two terms, the first enforcing a desired dose distribution and the second guaranteeing a smooth dose rate variation between successive gantry angles. A gantry rotation is discretized into 180 beam angles and for each beam angle, only one MLC aperture is allowed. The apertures are generated one by one in a sequentialmore » way. At each iteration of the column generation method, a deliverable MLC aperture is generated for one of the unoccupied beam angles by solving a subproblem with the consideration of MLC mechanic constraints. A subsequent master problem is then solved to determine the dose rate at all currently generated apertures by minimizing the cost function. When all 180 beam angles are occupied, the optimization completes, yielding a set of deliverable apertures and associated dose rates that produce a high quality plan. Results: The algorithm was preliminarily tested on five prostate and five head-and-neck clinical cases, each with one full gantry rotation without any couch/collimator rotations. High quality VMAT plans have been generated for all ten cases with extremely high efficiency. It takes only 5-8 min on CPU (MATLAB code on an Intel Xeon 2.27 GHz CPU) and 18-31 s on GPU (CUDA code on an NVIDIA Tesla C1060 GPU card) to generate such plans. Conclusions: The authors have developed an aperture-based VMAT optimization algorithm which can generate clinically deliverable high quality treatment plans at very high efficiency.« less

Ultrafast treatment plan optimization for volumetric modulated arc therapy (VMAT).

PubMed

Men, Chunhua; Romeijn, H Edwin; Jia, Xun; Jiang, Steve B

2010-11-01

To develop a novel aperture-based algorithm for volumetric modulated are therapy (VMAT) treatment plan optimization with high quality and high efficiency. The VMAT optimization problem is formulated as a large-scale convex programming problem solved by a column generation approach. The authors consider a cost function consisting two terms, the first enforcing a desired dose distribution and the second guaranteeing a smooth dose rate variation between successive gantry angles. A gantry rotation is discretized into 180 beam angles and for each beam angle, only one MLC aperture is allowed. The apertures are generated one by one in a sequential way. At each iteration of the column generation method, a deliverable MLC aperture is generated for one of the unoccupied beam angles by solving a subproblem with the consideration of MLC mechanic constraints. A subsequent master problem is then solved to determine the dose rate at all currently generated apertures by minimizing the cost function. When all 180 beam angles are occupied, the optimization completes, yielding a set of deliverable apertures and associated dose rates that produce a high quality plan. The algorithm was preliminarily tested on five prostate and five head-and-neck clinical cases, each with one full gantry rotation without any couch/collimator rotations. High quality VMAT plans have been generated for all ten cases with extremely high efficiency. It takes only 5-8 min on CPU (MATLAB code on an Intel Xeon 2.27 GHz CPU) and 18-31 s on GPU (CUDA code on an NVIDIA Tesla C1060 GPU card) to generate such plans. The authors have developed an aperture-based VMAT optimization algorithm which can generate clinically deliverable high quality treatment plans at very high efficiency.

Candidate Dosimetric Predictors of Long-Term Swallowing Dysfunction After Oropharyngeal Intensity-Modulated Radiotherapy

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

Schwartz, David L., E-mail: docdls@mdanderson.or; Department of Experimental Diagnostic Imaging, University of Texas M. D. Anderson Cancer Center, Houston, TX; Hutcheson, Katherine

2010-12-01

Purpose: To investigate long-term swallowing function in oropharyngeal cancer patients treated with intensity-modulated radiotherapy (IMRT), and to identify novel dose-limiting criteria predictive for dysphagia. Methods and Materials: Thirty-one patients with Stage IV oropharyngeal squamous carcinoma enrolled on a Phase II trial were prospectively evaluated by modified barium swallow studies at baseline, and 6, 12, and 24 months post-IMRT treatment. Candidate dysphagia-associated organs at risk were retrospectively contoured into original treatment plans. Twenty-one (68%) cases were base of tongue and 10 (32%) were tonsil. Stage distribution was T1 (12 patients), T2 (10), T3 (4), T4 (2), and TX (3), and N2more » (24), N3 (5), and NX (2). Median age was 52.8 years (range, 42-78 years). Thirteen patients (42%) received concurrent chemotherapy during IMRT. Thirteen (42%) were former smokers. Mean dose to glottic larynx for the cohort was limited to 18 Gy (range, 6-39 Gy) by matching IMRT to conventional low-neck fields. Results: Dose-volume constraints (V30 < 65% and V35 < 35% for anterior oral cavity and V55 < 80% and V65 < 30% for high superior pharyngeal constrictors) predictive for objective swallowing dysfunction were identified by univariate and multivariate analyses. Aspiration and feeding tube dependence were observed in only 1 patient at 24 months. Conclusions: In the context of glottic laryngeal shielding, we describe candidate oral cavity and superior pharyngeal constrictor organs at risk and dose-volume constraints associated with preserved long-term swallowing function; these constraints are currently undergoing prospective validation. Strict protection of the glottic larynx via beam-split IMRT techniques promises to make chronic aspiration an uncommon outcome.« less

Skin dose measurements using MOSFET and TLD for head and neck patients treated with tomotherapy.

PubMed

Kinhikar, Rajesh A; Murthy, Vedang; Goel, Vineeta; Tambe, Chandrashekar M; Dhote, Dipak S; Deshpande, Deepak D

2009-09-01

The purpose of this work was to estimate skin dose for the patients treated with tomotherapy using metal oxide semiconductor field-effect transistors (MOSFETs) and thermoluminescent dosimeters (TLDs). In vivo measurements were performed for two head and neck patients treated with tomotherapy and compared to TLD measurements. The measurements were subsequently carried out for five days to estimate the inter-fraction deviations in MOSFET measurements. The variation between skin dose measured with MOSFET and TLD for first patient was 2.2%. Similarly, the variation of 2.3% was observed between skin dose measured with MOSFET and TLD for second patient. The tomotherapy treatment planning system overestimated the skin dose as much as by 10-12% when compared to both MOSFET and TLD. However, the MOSFET measured patient skin doses also had good reproducibility, with inter-fraction deviations ranging from 1% to 1.4%. MOSFETs may be used as a viable dosimeter for measuring skin dose in areas where the treatment planning system may not be accurate.

Role of particle radiotherapy in the management of head and neck cancer.

PubMed

Laramore, George E

2009-05-01

Modern imaging techniques and powerful computers allow a radiation oncologist to design treatments delivering higher doses of radiation than previously possible. Dose distributions imposed by the physics of 'standard' photon and electron beams limit further dose escalation. Hadron radiotherapy offers advantages in either dose distribution and/or improved radiobiology that may significantly improve the treatment of certain head and neck malignancies. Clinical studies support the effectiveness of fast-neutron radiotherapy in the treatment of major and minor salivary gland tumors. Data show highly favorable outcomes with proton radiotherapy for skull-base malignancies and tumors near highly critical normal tissues compared with that expected with standard radiotherapy. Heavy-ion radiotherapy clinical studies are mainly being conducted with fully stripped carbon ions, and limited data seem to indicate a possible improvement over proton radiotherapy for the same subset of radioresistant tumors where neutrons show a benefit over photons. Fast-neutron radiotherapy has different radiobiological properties compared with standard radiotherapy but similar depth dose distributions. Its role in the treatment of head and neck cancer is currently limited to salivary gland malignancies and certain radioresistant tumors such as sarcomas. Protons have the same radiobiological properties as standard radiotherapy beams but more optimal depth dose distributions, making it particularly advantageous when treating tumors adjacent to highly critical structures. Heavy ions combine the radiobiological properties of fast neutrons with the physical dose distributions of protons, and preliminary data indicate their utility for radioresistant tumors adjacent to highly critical structures.

Experimental verification of using nanostructured ceramic implants and osteograft

NASA Astrophysics Data System (ADS)

Rerikh, V. V.; Lastevskiy, A. D.; Sadovoy, M. A.; Zaidman, A. M.; Bataev, A. V.; Predein, Yu. A.; Avetisyan, A. R.; Romanenko, V. V.; Mamonova, E. V.; Nikulina, A. A.; Semantsova, E. S.; Smirnov, A. I.

2017-09-01

Ventral interbody fusion was carried out in 8 mini pigs in order to determine the effectiveness of anterior stabilization of the vertebral unit with implants made of nanostructured alumina ceramics using cellular technologies to form a bone block. A ceramic cage with a through cylindrical orifice in the center was implanted into the interbody gap; either cellular osteograft (group 1) or cellular autograft (group 2) was placed in it. The adjacent vertebrae were fixed anteriorly with a ceramic plate containing 4 screws. Bone block formation was studied radiographically, morphologically, and by MSCT. The signs of osteointegration of ceramic implants were observed in both groups after 90 days. MSCT and morphological analysis revealed the formation of the osteoceramic block and completed osteogenesis in the bone-graft contact region in group 1 compared to the control group (p < 0.05).

A Case of an Upper Gastrointestinal Bleeding Due to a Ruptured Dissection of a Right Aortic Arch

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

Born, Christine; Forster, Andreas; Rock, Clemens

2003-09-15

We report a case of severe upper gastrointestinal hemorrhage with a rare underlying cause. The patient was unconscious when he was admitted to the hospital. No chest radiogram was performed. Routine diagnostic measures, including endoscopy, failed to reveal the origin of the bleeding, which was believed to originate from the esophagus secondary to a peptic ulcer or varices. Exploratory laparotomy added no further information, but contrast-enhanced multislice computed tomography (MSCT) of the chest showed dextroposition of the widened aortic arch with a ruptured type-B dissection and a consecutive aorto-esophageal fistula (AEF). The patient died on the day of admission. Noninvasivemore » MSCT angiography gives rapid diagnostic information on patients with occult upper gastrointestinal bleeding and should be considered before more invasive conventional angiography or surgery.« less

Calcium score of coronary artery stratifies the risk of obstructive coronary artery diseases.

PubMed

Ibrahim, O; Oteh, M; Anwar, I R; Che Hassan, H H; Choor, C K; Hamzaini, A H; Rahman, M M

2013-01-01

Coronary heart disease is a major health problem in Malaysia with high morbidity and mortality. Common primary screening tool of cardiovascular risk stratification is exercise treadmill test (ETT). This communication is to determine the performance of coronary artery calcium score a new method to stratify the presence of obstructive coronary artery disease (CAD) in comparison to traditional ETT in patients having coronary artery diseases. Patients between 30 to 60 years old attended the ETT to screen for ischemic heart disease were recruited for Agatston coronary artery calcium score (CACS) of multi-sliced computed tomography (MSCT). Subsequently all patients underwent a full MSCT coronary angiography. The major determinant was the state of CAD whether obstructive (50% stenosis or more) or non-obstructive (less than 50% stenosis). All patients diagnosed with obstructive CAD on MSCT coronary angiogram were subjected to invasive coronary angiogram (ICA) to confirm the findings and planned the need for revascularization. The CACS was 100% sensitivity and 97.5% specificity in detecting obstructive CAD at the optimal cut-off value of 106.5 and above. The positive predictive value (PPV) at CACS ≥ 106 was 71.4% and the negative predictive value (NPV) was consistent at 100%. Compare to ETT, the CACS discriminative value and diagnostic performance was much better (PPV 71.4% vs. 45.5%), respectively. CACS can be a good diagnostic screening tool in patients suspected of CAD, and particularly within the non-diagnostic ETT subgroup with low to moderate cardiovascular risks.

Ontogeny of the spheno-occipital synchondrosis in a modern Queensland, Australian population using computed tomography.

PubMed

Lottering, Nicolene; MacGregor, Donna M; Alston, Clair L; Gregory, Laura S

2015-05-01

Due to disparity regarding the age at which skeletal maturation of the spheno-occipital synchondrosis occurs in forensic and biological literature, this study provides recalibrated multislice computed tomography (MSCT) age standards for the Australian (Queensland) population, using a Bayesian statistical approach. The sample comprises retrospective cranial/cervical MSCT scans obtained from 448 males and 416 females aged birth to 20 years from the Skeletal Biology and Forensic Anthropology Research Osteological Database. Fusion status of the synchondrosis was scored using a modified six-stage scoring tier on an MSCT platform, with negligible observer error (κ = 0.911 ± 0.04, intraclass correlation coefficient = 0.994). Bayesian transition analysis indicates that females are most likely to transition to complete fusion at 13.1 years and males at 15.6 years. Posterior densities were derived for each morphological stage, with complete fusion of the synchondrosis attained in all Queensland males over 16.3 years of age and females aged 13.8 years and older. The results demonstrate significant sexual dimorphism in synchondrosis fusion and are suggestive of intrapopulation variation between major geographic regions in Australia. This study contributes to the growing repository of contemporary anthropological standards calibrated for the Queensland milieu to improve the efficacy of the coronial process for medicolegal death investigation. As a stand-alone age indicator, the basicranial synchondrosis may be consulted as an exclusion criterion when determining the age of majority that constitutes 17 years in Queensland forensic practice. © 2014 Wiley Periodicals, Inc.

SU-D-16A-02: A Novel Methodology for Accurate, Semi-Automated Delineation of Oral Mucosa for Radiation Therapy Dose-Response Studies

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

Dean, J; Welsh, L; Gulliford, S

Purpose: The significant morbidity caused by radiation-induced acute oral mucositis means that studies aiming to elucidate dose-response relationships in this tissue are a high priority. However, there is currently no standardized method for delineating the mucosal structures within the oral cavity. This report describes the development of a methodology to delineate the oral mucosa accurately on CT scans in a semi-automated manner. Methods: An oral mucosa atlas for automated segmentation was constructed using the RayStation Atlas-Based Segmentation (ABS) module. A radiation oncologist manually delineated the full surface of the oral mucosa on a planning CT scan of a patient receivingmore » radiotherapy (RT) to the head and neck region. A 3mm fixed annulus was added to incorporate the mucosal wall thickness. This structure was saved as an atlas template. ABS followed by model-based segmentation was performed on four further patients sequentially, adding each patient to the atlas. Manual editing of the automatically segmented structure was performed. A dose comparison between these contours and previously used oral cavity volume contours was performed. Results: The new approach was successful in delineating the mucosa, as assessed by an experienced radiation oncologist, when applied to a new series of patients receiving head and neck RT. Reductions in the mean doses obtained when using the new delineation approach, compared with the previously used technique, were demonstrated for all patients (median: 36.0%, range: 25.6% – 39.6%) and were of a magnitude that might be expected to be clinically significant. Differences in the maximum dose that might reasonably be expected to be clinically significant were observed for two patients. Conclusion: The method developed provides a means of obtaining the dose distribution delivered to the oral mucosa more accurately than has previously been achieved. This will enable the acquisition of high quality dosimetric data for use in dose-response studies. We would like to thank the Engineering and Physical Sciences Research Council for funding. We acknowledge support from the NIHR RM/ICR Biomedical Research Centre. RayStatation was used under an evaluation agreement with RaySearch Laboratories AB.« less

A comprehensive formulation for volumetric modulated arc therapy planning

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

Nguyen, Dan; Lyu, Qihui; Ruan, Dan

2016-07-15

Purpose: Volumetric modulated arc therapy (VMAT) is a widely employed radiation therapy technique, showing comparable dosimetry to static beam intensity modulated radiation therapy (IMRT) with reduced monitor units and treatment time. However, the current VMAT optimization has various greedy heuristics employed for an empirical solution, which jeopardizes plan consistency and quality. The authors introduce a novel direct aperture optimization method for VMAT to overcome these limitations. Methods: The comprehensive VMAT (comVMAT) planning was formulated as an optimization problem with an L2-norm fidelity term to penalize the difference between the optimized dose and the prescribed dose, as well as an anisotropicmore » total variation term to promote piecewise continuity in the fluence maps, preparing it for direct aperture optimization. A level set function was used to describe the aperture shapes and the difference between aperture shapes at adjacent angles was penalized to control MLC motion range. A proximal-class optimization solver was adopted to solve the large scale optimization problem, and an alternating optimization strategy was implemented to solve the fluence intensity and aperture shapes simultaneously. Single arc comVMAT plans, utilizing 180 beams with 2° angular resolution, were generated for a glioblastoma multiforme case, a lung (LNG) case, and two head and neck cases—one with three PTVs (H&N{sub 3PTV}) and one with foue PTVs (H&N{sub 4PTV})—to test the efficacy. The plans were optimized using an alternating optimization strategy. The plans were compared against the clinical VMAT (clnVMAT) plans utilizing two overlapping coplanar arcs for treatment. Results: The optimization of the comVMAT plans had converged within 600 iterations of the block minimization algorithm. comVMAT plans were able to consistently reduce the dose to all organs-at-risk (OARs) as compared to the clnVMAT plans. On average, comVMAT plans reduced the max and mean OAR dose by 6.59% and 7.45%, respectively, of the prescription dose. Reductions in max dose and mean dose were as high as 14.5 Gy in the LNG case and 15.3 Gy in the H&N{sub 3PTV} case. PTV coverages measured by D95, D98, and D99 were within 0.25% of the prescription dose. By comprehensively optimizing all beams, the comVMAT optimizer gained the freedom to allow some selected beams to deliver higher intensities, yielding a dose distribution that resembles a static beam IMRT plan with beam orientation optimization. Conclusions: The novel nongreedy VMAT approach simultaneously optimizes all beams in an arc and then directly generates deliverable apertures. The single arc VMAT approach thus fully utilizes the digital Linac’s capability in dose rate and gantry rotation speed modulation. In practice, the new single VMAT algorithm generates plans superior to existing VMAT algorithms utilizing two arcs.« less

Efficacy of lead foil for reducing doses in the head and neck: a simulation study using digital intraoral systems

PubMed Central

Silva, A I V; Brasil, D M; Vasconcelos, K F; Haiter Neto, F; Boscolo, F N

2015-01-01

Objectives: To assess the efficacy of lead foils in reducing the radiation dose received by different anatomical sites of the head and neck during periapical intraoral examinations performed with digital systems. Methods: Images were acquired through four different manners: phosphor plate (PSP; VistaScan® system; Dürr Dental GmbH, Bissingen, Germany) alone, PSP plus lead foil, complementary metal oxide semiconductor (CMOS; DIGORA® Toto, Soredex®, Tuusula, Finland) alone and CMOS plus lead foil. Radiation dose was measured after a full-mouth periapical series (14 radiographs) using the long-cone paralleling technique. Lithium fluoride (LiF 100) thermoluminescent dosemeters were placed in an anthropomorphic phantom at points corresponding to the tongue, thyroid, crystalline lenses, parotid glands and maxillary sinuses. Results: Dosemeter readings demonstrated the efficacy of the addition of lead foil in the intraoral digital X-ray systems provided in reducing organ doses in the selected structures, approximately 32% in the PSP system and 59% in the CMOS system. Conclusions: The use of lead foils associated with digital X-ray sensors is an effective alternative for the protection of different anatomical sites of the head and neck during full-mouth periapical series acquisition. PMID:26084474

Brachytherapy after salvage surgery in cases with large isolated cervical recurrence of squamous cell carcinoma in the previously irradiated neck.

PubMed

Miroir, Jessica; Biau, Julian; Saroul, Nicolas; Moreira, Jean-François; Russier, Marc; Lapeyre, Michel

2016-09-01

Perioperative brachytherapy after salvage surgery is a therapeutic option in patients with cervical relapse of a primary, controlled, previously irradiated head and neck squamous cell carcinoma. The purpose of this study was to analyze the outcome of this treatment. Between 2008 and 2013, 8 patients underwent cervical brachytherapy after neck dissection. The mean node size was 5.5 cm. Recurrence occurred in an irradiated field (median dose, 50 Gy). Brachytherapy was performed with (192) iridium and dosimetry in accord with the rules of the Paris system. The dose was 60 to 62.7 Gy on the reference isodose. The mean follow-up was 17 months. The median overall survival (OS) was 12 months. The OS was 19% at 2 years and 0% at 5 years. A grade 5 postoperative adverse event occurred in 1 patient. At 6 months, all patients had a grade 3 neck soft tissue fibrosis. One patient had a lethal hemorrhage at 56 months. Brachytherapy is toxic in this population with poor OS. © 2016 Wiley Periodicals, Inc. Head Neck 38: E2490-E2494, 2016. © 2016 Wiley Periodicals, Inc.

The Potential for Tumor Suppressor Gene Therapy in Head and Neck Cancer

PubMed Central

Birkeland, Andrew C.; Ludwig, Megan L.; Spector, Matthew E.; Brenner, J. Chad

2016-01-01

Head and neck squamous cell carcinoma remains a highly morbid and fatal disease. Importantly, genomic sequencing of head and neck cancers has identified frequent mutations in tumor suppressor genes. While targeted therapeutics increasingly are being investigated in head and neck cancer, the majority of these agents are against overactive/overexpressed oncogenes. Therapy to restore lost tumor suppressor gene function remains a key and under-addressed niche in trials for head and neck cancer. Recent advances in gene editing have captured the interest of both the scientific community and the public. As our technology for gene editing and gene expression modulation improves, addressing lost tumor suppressor gene function in head and neck cancers is becoming a reality. This review will summarize new techniques, challenges to implementation, future directions, and ethical ramifications of gene therapy in head and neck cancer. PMID:26896601

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

Role of the parameters involved in the plan optimization based on the generalized equivalent uniform dose and radiobiological implications

NASA Astrophysics Data System (ADS)

Widesott, L.; Strigari, L.; Pressello, M. C.; Benassi, M.; Landoni, V.

2008-03-01

We investigated the role and the weight of the parameters involved in the intensity modulated radiation therapy (IMRT) optimization based on the generalized equivalent uniform dose (gEUD) method, for prostate and head-and-neck plans. We systematically varied the parameters (gEUDmax and weight) involved in the gEUD-based optimization of rectal wall and parotid glands. We found that the proper value of weight factor, still guaranteeing planning treatment volumes coverage, produced similar organs at risks dose-volume (DV) histograms for different gEUDmax with fixed a = 1. Most of all, we formulated a simple relation that links the reference gEUDmax and the associated weight factor. As secondary objective, we evaluated plans obtained with the gEUD-based optimization and ones based on DV criteria, using the normal tissue complication probability (NTCP) models. gEUD criteria seemed to improve sparing of rectum and parotid glands with respect to DV-based optimization: the mean dose, the V40 and V50 values to the rectal wall were decreased of about 10%, the mean dose to parotids decreased of about 20-30%. But more than the OARs sparing, we underlined the halving of the OARs optimization time with the implementation of the gEUD-based cost function. Using NTCP models we enhanced differences between the two optimization criteria for parotid glands, but no for rectum wall.

SU-E-T-92: Achieving Desirable Lung Doses in Total Body Irradiation Based On in Vivo Dosimetry and Custom Tissue Compensation

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

Cui, G; Shiu, A; Zhou, S

Purpose: To achieve desirable lung doses in total body irradiation (TBI) based on in vivo dosimetry and custom tissue compensation. Methods: The 15 MV photon beam of a Varian TrueBeam STx linac was used for TBI. Patients were positioned in the lateral decubitus position for AP/PA treatment delivery. Dose was calculated using the midpoint of the separation distance across the patient’s umbilicus. Patients received 200 cGy twice daily for 3 days. The dose rate at the patient’s midplane was approximately 10 cGy/min. Cerrobend blocks with a 5-HVL thickness were used for the primary lung shielding. A custom styrofoam holder formore » rice-flour filled bags was created based on the lung block cutouts. This was used to provide further lung shielding based on in vivo dose measurements. Lucite plates and rice-flour bags were placed in the head, neck, chest, and lower extremity regions during the treatment to compensate for the beam off-axis output variations. Two patients were included in the study. Patients 1 and 2 received a craniospinal treatment (1080 cGy) and a mediastinum treatment (2520 cGy), respectively, before the TBI. During the TBI nanoDot dosimeters were placed on the patient skin in the forehead, neck, umbilicus, and lung regions for dose monitoring. The doses were readout immediately after the treatment. Based on the readings, fine tuning of the thickness of the rice-flour filled bags was exploited to achieve the desirable lung doses. Results: For both patients the mean lung doses, which took into consideration all treatments, were controlled within 900 +/−10% cGy, as desired. Doses to the forehead, neck, and umbilicus were achieved within +/−10% of the prescribed dose (1200 cGy). Conclusion: A reliable and robust method was developed to achieve desirable lung doses and uniform body dose in TBI based on in vivo dosimetry and custom tissue compensator.« less

Monte Carlo treatment planning with modulated electron radiotherapy: framework development and application

NASA Astrophysics Data System (ADS)

Alexander, Andrew William

Within the field of medical physics, Monte Carlo radiation transport simulations are considered to be the most accurate method for the determination of dose distributions in patients. The McGill Monte Carlo treatment planning system (MMCTP), provides a flexible software environment to integrate Monte Carlo simulations with current and new treatment modalities. A developing treatment modality called energy and intensity modulated electron radiotherapy (MERT) is a promising modality, which has the fundamental capabilities to enhance the dosimetry of superficial targets. An objective of this work is to advance the research and development of MERT with the end goal of clinical use. To this end, we present the MMCTP system with an integrated toolkit for MERT planning and delivery of MERT fields. Delivery is achieved using an automated "few leaf electron collimator" (FLEC) and a controller. Aside from the MERT planning toolkit, the MMCTP system required numerous add-ons to perform the complex task of large-scale autonomous Monte Carlo simulations. The first was a DICOM import filter, followed by the implementation of DOSXYZnrc as a dose calculation engine and by logic methods for submitting and updating the status of Monte Carlo simulations. Within this work we validated the MMCTP system with a head and neck Monte Carlo recalculation study performed by a medical dosimetrist. The impact of MMCTP lies in the fact that it allows for systematic and platform independent large-scale Monte Carlo dose calculations for different treatment sites and treatment modalities. In addition to the MERT planning tools, various optimization algorithms were created external to MMCTP. The algorithms produced MERT treatment plans based on dose volume constraints that employ Monte Carlo pre-generated patient-specific kernels. The Monte Carlo kernels are generated from patient-specific Monte Carlo dose distributions within MMCTP. The structure of the MERT planning toolkit software and optimization algorithms are demonstrated. We investigated the clinical significance of MERT on spinal irradiation, breast boost irradiation, and a head and neck sarcoma cancer site using several parameters to analyze the treatment plans. Finally, we investigated the idea of mixed beam photon and electron treatment planning. Photon optimization treatment planning tools were included within the MERT planning toolkit for the purpose of mixed beam optimization. In conclusion, this thesis work has resulted in the development of an advanced framework for photon and electron Monte Carlo treatment planning studies and the development of an inverse planning system for photon, electron or mixed beam radiotherapy (MBRT). The justification and validation of this work is found within the results of the planning studies, which have demonstrated dosimetric advantages to using MERT or MBRT in comparison to clinical treatment alternatives.

Development and application of computer assisted optimal method for treatment of femoral neck fracture.

PubMed

Wang, Monan; Zhang, Kai; Yang, Ning

2018-04-09

To help doctors decide their treatment from the aspect of mechanical analysis, the work built a computer assisted optimal system for treatment of femoral neck fracture oriented to clinical application. The whole system encompassed the following three parts: Preprocessing module, finite element mechanical analysis module, post processing module. Preprocessing module included parametric modeling of bone, parametric modeling of fracture face, parametric modeling of fixed screw and fixed position and input and transmission of model parameters. Finite element mechanical analysis module included grid division, element type setting, material property setting, contact setting, constraint and load setting, analysis method setting and batch processing operation. Post processing module included extraction and display of batch processing operation results, image generation of batch processing operation, optimal program operation and optimal result display. The system implemented the whole operations from input of fracture parameters to output of the optimal fixed plan according to specific patient real fracture parameter and optimal rules, which demonstrated the effectiveness of the system. Meanwhile, the system had a friendly interface, simple operation and could improve the system function quickly through modifying single module.

Scattered radiation from dental metallic crowns in head and neck radiotherapy.

PubMed

Shimozato, T; Igarashi, Y; Itoh, Y; Yamamoto, N; Okudaira, K; Tabushi, K; Obata, Y; Komori, M; Naganawa, S; Ueda, M

2011-09-07

We aimed to estimate the scattered radiation from dental metallic crowns during head and neck radiotherapy by irradiating a jaw phantom with external photon beams. The phantom was composed of a dental metallic plate and hydroxyapatite embedded in polymethyl methacrylate. We used radiochromic film measurement and Monte Carlo simulation to calculate the radiation dose and dose distribution inside the phantom. To estimate dose variations in scattered radiation under different clinical situations, we altered the incident energy, field size, plate thickness, plate depth and plate material. The simulation results indicated that the dose at the incident side of the metallic dental plate was approximately 140% of that without the plate. The differences between dose distributions calculated with the radiation treatment-planning system (TPS) algorithms and the data simulation, except around the dental metallic plate, were 3% for a 4 MV photon beam. Therefore, we should carefully consider the dose distribution around dental metallic crowns determined by a TPS.

Scattered radiation from dental metallic crowns in head and neck radiotherapy

NASA Astrophysics Data System (ADS)

Shimozato, T.; Igarashi, Y.; Itoh, Y.; Yamamoto, N.; Okudaira, K.; Tabushi, K.; Obata, Y.; Komori, M.; Naganawa, S.; Ueda, M.

2011-09-01

We aimed to estimate the scattered radiation from dental metallic crowns during head and neck radiotherapy by irradiating a jaw phantom with external photon beams. The phantom was composed of a dental metallic plate and hydroxyapatite embedded in polymethyl methacrylate. We used radiochromic film measurement and Monte Carlo simulation to calculate the radiation dose and dose distribution inside the phantom. To estimate dose variations in scattered radiation under different clinical situations, we altered the incident energy, field size, plate thickness, plate depth and plate material. The simulation results indicated that the dose at the incident side of the metallic dental plate was approximately 140% of that without the plate. The differences between dose distributions calculated with the radiation treatment-planning system (TPS) algorithms and the data simulation, except around the dental metallic plate, were 3% for a 4 MV photon beam. Therefore, we should carefully consider the dose distribution around dental metallic crowns determined by a TPS.

A method to determine the planar dose distributions in patient undergone radiotherapy

NASA Astrophysics Data System (ADS)

Cilla, S.; Viola, P.; Augelli, B. G.; D'Onofrio, G.; Grimaldi, L.; Craus, M.; Digesù, C.; Deodato, F.; Macchia, G.; Morganti, A. G.; Fidanzio, A.; Azario, L.; Piermattei, A.

2008-06-01

A 2D-array equipped with 729 vented plane parallel ion-chambers has been calibrated as a portal dose detector for radiotherapy in vivo measurements. The array has been positioned by a radiographic film stand at 120 cm from the source orthogonal to the radiotherapy beam delivered with the gantry angle at 180°. The collision between the 2D-array and the patient's couch have been avoided. In this work, using the measurements of the portal detector, we present a method to reconstruct the dose variations in the patient treated with step and shoot intensity-modulated beams (IMRT) for head-neck tumours. For this treatment morphological changes often occur during the fractionated therapy. In a first step an in-house software supplied the comparison between the measured portal dose and the one computed by a commercial treatment planning system within the field of view of the computed tomography (CT) scanner. For each patient, the percentage Pγ of chambers, where the comparison is in agreement within a selected acceptance criteria, was determined 8 times. At the first radiotherapy fraction the γ-index analysis supplied Pγ values of about 95%, within acceptance criteria in terms of dose-difference, ΔD, and distance-agreement, Δd, that was equal to 5% and 4 mm, respectively. These acceptance criteria were taken into account for small errors in the patient's set-up reproducibility and for the accuracy of the portal dose calculated by the treatment planning system (TPS) in particular when the beam was attenuated by inhomogeneous tissues and the shape of the head-neck body contours were irregular. During the treatment, some patients showed a reduction of the Pγ below 90% because due to radiotherapy treatment there was a change of the patient's morphology. In a second step a method, based on dosimetric measurements that used standard phantoms, supplied the percentage dose variations in a coronal plane of the patient using the percentage dose variations measured by the 2D-array portal detector. The results showed that the dose variations due to the change of the patient's morphology reached 15% and such discrepancies were displayed on the digitally reconstructed radiography of the patient. The dose discrepancies were confirmed by the hybrid plan obtained by the treatment planning system. The good results here reported show that once it is possible to have the portal dose distributions even for other gantry angles, these tests could be introduced in the clinical protocol to have major support to decide when to repeat the patient's CT scan and to re-plan the new IMRT dose calculation.

Statistical variability and confidence intervals for planar dose QA pass rates

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

Bailey, Daniel W.; Nelms, Benjamin E.; Attwood, Kristopher

Purpose: The most common metric for comparing measured to calculated dose, such as for pretreatment quality assurance of intensity-modulated photon fields, is a pass rate (%) generated using percent difference (%Diff), distance-to-agreement (DTA), or some combination of the two (e.g., gamma evaluation). For many dosimeters, the grid of analyzed points corresponds to an array with a low areal density of point detectors. In these cases, the pass rates for any given comparison criteria are not absolute but exhibit statistical variability that is a function, in part, on the detector sampling geometry. In this work, the authors analyze the statistics ofmore » various methods commonly used to calculate pass rates and propose methods for establishing confidence intervals for pass rates obtained with low-density arrays. Methods: Dose planes were acquired for 25 prostate and 79 head and neck intensity-modulated fields via diode array and electronic portal imaging device (EPID), and matching calculated dose planes were created via a commercial treatment planning system. Pass rates for each dose plane pair (both centered to the beam central axis) were calculated with several common comparison methods: %Diff/DTA composite analysis and gamma evaluation, using absolute dose comparison with both local and global normalization. Specialized software was designed to selectively sample the measured EPID response (very high data density) down to discrete points to simulate low-density measurements. The software was used to realign the simulated detector grid at many simulated positions with respect to the beam central axis, thereby altering the low-density sampled grid. Simulations were repeated with 100 positional iterations using a 1 detector/cm{sup 2} uniform grid, a 2 detector/cm{sup 2} uniform grid, and similar random detector grids. For each simulation, %/DTA composite pass rates were calculated with various %Diff/DTA criteria and for both local and global %Diff normalization techniques. Results: For the prostate and head/neck cases studied, the pass rates obtained with gamma analysis of high density dose planes were 2%-5% higher than respective %/DTA composite analysis on average (ranging as high as 11%), depending on tolerances and normalization. Meanwhile, the pass rates obtained via local normalization were 2%-12% lower than with global maximum normalization on average (ranging as high as 27%), depending on tolerances and calculation method. Repositioning of simulated low-density sampled grids leads to a distribution of possible pass rates for each measured/calculated dose plane pair. These distributions can be predicted using a binomial distribution in order to establish confidence intervals that depend largely on the sampling density and the observed pass rate (i.e., the degree of difference between measured and calculated dose). These results can be extended to apply to 3D arrays of detectors, as well. Conclusions: Dose plane QA analysis can be greatly affected by choice of calculation metric and user-defined parameters, and so all pass rates should be reported with a complete description of calculation method. Pass rates for low-density arrays are subject to statistical uncertainty (vs. the high-density pass rate), but these sampling errors can be modeled using statistical confidence intervals derived from the sampled pass rate and detector density. Thus, pass rates for low-density array measurements should be accompanied by a confidence interval indicating the uncertainty of each pass rate.« less

A dual two dimensional electronic portal imaging device transit dosimetry model based on an empirical quadratic formalism

PubMed Central

Metwaly, M; Glegg, M; Baggarley, S P; Elliott, A

2015-01-01

Objective: This study describes a two dimensional electronic portal imaging device (EPID) transit dosimetry model that can predict either: (1) in-phantom exit dose, or (2) EPID transit dose, for treatment verification. Methods: The model was based on a quadratic equation that relates the reduction in intensity to the equivalent path length (EPL) of the attenuator. In this study, two sets of quadratic equation coefficients were derived from calibration dose planes measured with EPID and ionization chamber in water under reference conditions. With two sets of coefficients, EPL can be calculated from either EPID or treatment planning system (TPS) dose planes. Consequently, either the in-phantom exit dose or the EPID transit dose can be predicted from the EPL. The model was tested with two open, five wedge and seven sliding window prostate and head and neck intensity-modulated radiation therapy (IMRT) fields on phantoms. Results were analysed using absolute gamma analysis (3%/3 mm). Results: The open fields gamma pass rates were >96.8% for all comparisons. For wedge and IMRT fields, comparisons between predicted and TPS-computed in-phantom exit dose resulted in mean gamma pass rate of 97.4% (range, 92.3–100%). As for the comparisons between predicted and measured EPID transit dose, the mean gamma pass rate was 97.5% (range, 92.6–100%). Conclusion: An EPID transit dosimetry model that can predict in-phantom exit dose and EPID transit dose was described and proven to be valid. Advances in knowledge: The described model is practical, generic and flexible to encourage widespread implementation of EPID dosimetry for the improvement of patients' safety in radiotherapy. PMID:25969867

Novel Radiobiological Gamma Index for Evaluation of 3-Dimensional Predicted Dose Distribution

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

Sumida, Iori, E-mail: sumida@radonc.med.osaka-u.ac.jp; Yamaguchi, Hajime; Kizaki, Hisao

2015-07-15

Purpose: To propose a gamma index-based dose evaluation index that integrates the radiobiological parameters of tumor control (TCP) and normal tissue complication probabilities (NTCP). Methods and Materials: Fifteen prostate and head and neck (H&N) cancer patients received intensity modulated radiation therapy. Before treatment, patient-specific quality assurance was conducted via beam-by-beam analysis, and beam-specific dose error distributions were generated. The predicted 3-dimensional (3D) dose distribution was calculated by back-projection of relative dose error distribution per beam. A 3D gamma analysis of different organs (prostate: clinical [CTV] and planned target volumes [PTV], rectum, bladder, femoral heads; H&N: gross tumor volume [GTV], CTV,more » spinal cord, brain stem, both parotids) was performed using predicted and planned dose distributions under 2%/2 mm tolerance and physical gamma passing rate was calculated. TCP and NTCP values were calculated for voxels with physical gamma indices (PGI) >1. We propose a new radiobiological gamma index (RGI) to quantify the radiobiological effects of TCP and NTCP and calculate radiobiological gamma passing rates. Results: The mean RGI gamma passing rates for prostate cases were significantly different compared with those of PGI (P<.03–.001). The mean RGI gamma passing rates for H&N cases (except for GTV) were significantly different compared with those of PGI (P<.001). Differences in gamma passing rates between PGI and RGI were due to dose differences between the planned and predicted dose distributions. Radiobiological gamma distribution was visualized to identify areas where the dose was radiobiologically important. Conclusions: RGI was proposed to integrate radiobiological effects into PGI. This index would assist physicians and medical physicists not only in physical evaluations of treatment delivery accuracy, but also in clinical evaluations of predicted dose distribution.« less

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.

Ethanol sclerotherapy of head and neck venous malformations

PubMed Central

Orlando, José Luiz; Caldas, José Guilherme Mendes Pereira; Campos, Heloisa Galvão do Amaral; Nishinari, Kenji; Krutman, Mariana; Wolosker, Nelson

2014-01-01

ABSTRACT Objective: This retrospective study evaluated the results of sclerotherapy with low doses of ethanol for treatment of head and neck venous malformations. Methods: We treated 51 patients, 37 females. Median age was 23 years. Patients were treated with percutaneous intralesional injection of alcohol every two weeks and followed up prospectively for a median period of 18 months. Most lesions affected the face and cosmetic disfigurement was the most frequent complaint. Results: We performed a median of 7 sessions of sclerotherapy. Complete resolution or improvement was observed in 48 patients presented. Five cases of small skin ulceration, two cases of hyperpigmentation and two of paresthesia were documented; all of them were treated conservatively. Conclusion: Percutaneous sclerotherapy with low doses of ethanol is a safe and effective treatment modality for venous malformations affecting the head and neck. PMID:25003923

Recombinant human SDF-1α administration accelerates aneurysm neck reendothelialization in rabbit saccular aneurysm after flow diverter treatment.

PubMed

Li, Zifu; Zhao, Rui; Fang, Xinggen; Huang, Qinghai; Liu, Jianmin

2017-03-01

Reendothelialization in the aneurysm neck is pivotal to vascular repair for intracranial aneurysm after flow diverter (FD) implantation. Recombinant human stromal cell-derived factor 1α (rhSDF-1α) is a vital chemoattractant to stem cells and potentially facilitates reendothelialization. Here, we sought to investigate the therapeutic effects of intravenous administration of rhSDF-1α and uncover its potential mechanism for promoting aneurysm neck reendothelialization. Recombinant pET32a-186 plasmid was transformed into Escherichia coli to produce the rhSDF-1α protein with biological activity. FD was implanted into the elastase-induced saccular aneurysm in New Zealand white rabbits. rhSDF-1α (50 μg/kg/day) was intravenously administrated for consecutive 7 days after FD implantation. After these procedures, aneurysms were harvested after 2 or 4 weeks. Scanning electron microscopy was used to measure the neointima thickness and count the endothelial-like cells at aneurysm neck. Four weeks later, the mRNA levels of endothelial markers in the neointima at aneurysm neck were examined. Migration assay showed that rhSDF-1α could induce migration of endothelial progenitor cells in a dose-dependent manner. Two weeks after stent implantation, follow-up angiography showed partial aneurysm occlusion in one of each group and total aneurysm occlusion in 17 saccular aneurysm rabbits (9 of the rhSDF-1α group and 8 of the control group). No significant change of neointima thickness at aneurysm neck was observed. Intriguingly, more endothelial-like cells were observed at aneurysm neck in the rhSDF-1α group at 2 weeks (55 vs 13 cells per high-power field) and 4 weeks (104 vs 60 cells per high-power field). The mRNA levels of Tie-2, VE-cadherin, KDR and E-selectin were significantly enhanced compared with those of the control group. These results showed that intravenous administration of rhSDF-1α can accelerate reendothelialization in the aneurysm neck after FD implantation. Our study reveals an important role of rhSDF-1α in inducing aneurysm occlusion and suggests that it achieves its function through modulating the reendothelialization. © The Author 2017. Published by Oxford University Press on behalf of the Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Radiation concurrent with gemcitabine for locally advanced head and neck cancer: a phase I trial and intracellular drug incorporation study.

PubMed

Eisbruch, A; Shewach, D S; Bradford, C R; Littles, J F; Teknos, T N; Chepeha, D B; Marentette, L J; Terrell, J E; Hogikyan, N D; Dawson, L A; Urba, S; Wolf, G T; Lawrence, T S

2001-02-01

To examine the feasibility and dose-limiting toxicity (DLT) of once-weekly gemcitabine at doses predicted in preclinical studies to produce radiosensitization, concurrent with a standard course of radiation for locally advanced head and neck cancer. Tumor incorporation of gemcitabine triphosphate (dFdCTP) was measured to assess whether adequate concentrations were achieved at each dose level. Twenty-nine patients with unresectable head and neck cancer received a course of radiation (70 Gy over 7 weeks, 5 days weekly) concurrent with weekly infusions of low-dose gemcitabine. Tumor biopsies were performed after the first gemcitabine infusion (before radiation started), and the intracellular concentrations of dFdCTP were measured. Severe acute and late mucosal and pharyngeal-related DLT required de-escalation of gemcitabine dose in successive patient cohorts receiving dose levels of 300 mg/m(2)/wk, 150 mg/m(2)/wk, and 50 mg/m(2)/wk. No DLT was observed at 10 mg/m(2)/wk. The rate of endoscopy- and biopsy-assessed complete tumor response was 66% to 87% in the various cohorts. Tumor dFdCTP levels were similar in patients receiving 50 to 300 mg/m(2) (on average, 1.55 pmol/mg, SD 1.15) but were barely or not detectable at 10 mg/m(2). A high rate of acute and late mucosa-related DLT and a high rate of complete tumor response were observed in this regimen at the dose levels of 50 to 300 mg/m(2), which also resulted in similar, subcytotoxic intracellular dFdCTP concentrations. These results demonstrate significant tumor and normal tissue radiosensitization by low-dose gemcitabine. Different regimens of combined radiation and gemcitabine should be evaluated, based on newer preclinical data promising an improved therapeutic ratio.

Psychometric Validation of the M. D. Anderson Symptom Inventory-Head and Neck Module in the Spanish Language.

PubMed

Sánchez, Daniel; Chala, Andrés; Alvarez, Andrés; Payan, Catalina; Mendoza, Tito; Cleeland, Charles; Sanabria, Alvaro

2016-06-01

The assessment of cancer-related symptoms requires culturally adapted and psychometrically validated symptom assessment tools. The M. D. Anderson Symptom Inventory-Head and Neck Module (MDASI-HN) is a useful instrument for measuring symptom burden that was specifically developed for head and neck cancer patients. To validate the Spanish version of the MDASI-HN. We evaluated the psychometric features of the MDASI-HN in patients with head and neck cancer. We evaluated the item-scale correlations and the internal consistency. We conducted principal axis factoring to identify the underlying dimensions as a measure of construct validity. The convergence/concurrent validity was assessed with the University of Washington Quality of Life Questionnaire for Head and Neck Patients, and known-group validity and test-retest reliability also were assessed. One hundred thirty patients were included. The mean ± SD age was 60.5 ± 13.6 years; 68% of patients were male, 42% had laryngeal tumors, and 45.9% had Stage III tumors. Forty-seven percent of the patients underwent surgery, 55% underwent radiotherapy, and 36% underwent chemotherapy. The global Cronbach alpha for the HN module was 0.81. The factor analysis identified two factors (Factor 1: speech, mucus, coughing, and constipation; Factor 2: teeth, taste, sores, swallowing, and skin). The correlation with the global score of the University of Washington Quality of Life was -0.68. The difference in the MDASI-HN scores according to Eastern Cooperative Oncology Group performance status was statistically significant (2.72 vs. 4.01, P = 0.006). The intraclass test-retest correlation was 0.62. The Spanish version of the MDASI-HN is reliable and valid for evaluating cancer-related symptoms in head and neck cancer patients. Copyright © 2016 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All rights reserved.

Multi-Case Knowledge-Based IMRT Treatment Planning in Head and Neck Cancer

NASA Astrophysics Data System (ADS)

Grzetic, Shelby Mariah

Head and neck cancer (HNC) IMRT treatment planning is a challenging process that relies heavily on the planner's experience. Previously, we used the single, best match from a library of manually planned cases to semi-automatically generate IMRT plans for a new patient. The current multi-case Knowledge Based Radiation Therapy (MC-KBRT) study utilized different matching cases for each of six individual organs-at-risk (OARs), then combined those six cases to create the new treatment plan. From a database of 103 patient plans created by experienced planners, MC-KBRT plans were created for 40 (17 unilateral and 23 bilateral) HNC "query" patients. For each case, 2D beam's-eye-view images were used to find similar geometric "match" patients separately for each of 6 OARs. Dose distributions for each OAR from the 6 matching cases were combined and then warped to suit the query case's geometry. The dose-volume constraints were used to create the new query treatment plan without the need for human decision-making throughout the IMRT optimization. The optimized MC-KBRT plans were compared against the clinically approved plans and Version 1 (previous KBRT using only one matching case with dose warping) using the dose metrics: mean, median, and maximum (brainstem and cord+5mm) doses. Compared to Version 1, MC-KBRT had no significant reduction of the dose to any of the OARs in either unilateral or bilateral cases. Compared to the manually planned unilateral cases, there was significant reduction of the oral cavity mean/median dose (>2Gy) at the expense of the contralateral parotid. Compared to the manually planned bilateral cases, reduction of dose was significant in the ipsilateral parotid, larynx, and oral cavity (>3Gy mean/median) while maintaining PTV coverage. MC-KBRT planning in head and neck cancer generates IMRT plans with better dose sparing than manually created plans. MC-KBRT using multiple case matches does not show significant dose reduction compared to using a single match case with dose warping.

Non-invasive coronary angiography: the clinical value of multi-slice computed tomography in the assessment of patients with prior coronary bypass surgery. Evaluating grafts and native vessels.

PubMed

von Kiedrowski, Helge; Wiemer, Marcus; Franzke, Krista; Preuss, Rainer; Vaske, Bernhard; Butz, Thomas; Oldenburg, Olaf; Bitter, Thomas; Mahmood, Khalid; Burchert, Wolfram; Horstkotte, Dieter; Langer, Christoph

2009-02-01

Contrast enhanced multi-slice computed tomography (MSCT) is the leading modality in non-invasive coronary angiography (CTA) today. We investigated MSCT based assessment of coronary artery bypass grafts (CABG) by analyzing assets and drawbacks of CTA in order to define demands on latest technology. In a clinical setting 39 CABG patients (69.2 +/- 1.4 years; male n = 36) underwent CTA (collimation 16 x 0.75 mm, contrast medium 100 ml; 320 mAs, 120 KV). Ninety-seven CABG (61 venous, 36 arterial grafts) were evaluated. A subgroup of 18 patients underwent additional invasive coronary angiography (CA). CTA for CABG assessment resulted in an overall sensitivity (sens.) of 100%, specificity (spec.) of 92.4% and positive and negative predictive values (PPV, NPV) of 60% and 100%, respectively. CABG anastomoses showed slightly inferior diagnostic accuracy than other CABG segments. Limitations in imaging quality caused 21% unevaluable segments of the CABG anastomoses. Evaluation of native vessel segments proximal and distal to the anastomoses resulted in a sens, spec, PPV and NPV of 57.5, 94.6, 92 and 67.3%, respectively. With 28.5% unevaluable segments, the native vessel segments showed serious limitations in imaging quality. Radiation exposure was 9.88 +/- 3.20 mSv (9.69 +/- 3.25 mSv male; 12.08 +/- 1.35 mSv female). 16-slice MSCT based CABG assessment offers sufficient diagnostic accuracy. However, focussing on the bypass anastomoses and the native revascularized coronary arteries, clinical value is limited.

Fracture of the clavicle following radical neck dissection and postoperative radiotherapy: a case report and review of the literature

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

Strauss, M.; Bushey, M.J.; Chung, C.

1982-11-01

The treatment of head and neck cancer with radiotherapy and radical neck dissection has many recognized complications. Radiotherapy in therapeutic doses can produce devascularization and weakening of bone. Radical neck dissection results in altered mechanics of the shoulder girdle and a disruption of normally balanced forces acting on the clavicle. An unusual case of clavicle fracture which is considered to have resulted from an interaction of the effects of these therapies is discussed. An approach for recognizing and distinguishing this entity by its time course, and radiographic and nuclide bone scan appearance is presented.

SU-E-T-598: Parametric Equation for Quick and Reliable Estimate of Stray Neutron Doses in Proton Therapy and Application for Intracranial Tumor Treatments

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

Bonfrate, A; Farah, J; Sayah, R

2015-06-15

Purpose: Development of a parametric equation suitable for a daily use in routine clinic to provide estimates of stray neutron doses in proton therapy. Methods: Monte Carlo (MC) calculations using the UF-NCI 1-year-old phantom were exercised to determine the variation of stray neutron doses as a function of irradiation parameters while performing intracranial treatments. This was done by individually changing the proton beam energy, modulation width, collimator aperture and thickness, compensator thickness and the air gap size while their impact on neutron doses were put into a single equation. The variation of neutron doses with distance from the target volumemore » was also included in it. Then, a first step consisted in establishing the fitting coefficients by using 221 learning data which were neutron absorbed doses obtained with MC simulations while a second step consisted in validating the final equation. Results: The variation of stray neutron doses with irradiation parameters were fitted with linear, polynomial, etc. model while a power-law model was used to fit the variation of stray neutron doses with the distance from the target volume. The parametric equation fitted well MC simulations while establishing fitting coefficients as the discrepancies on the estimate of neutron absorbed doses were within 10%. The discrepancy can reach ∼25% for the bladder, the farthest organ from the target volume. Finally, the validation showed results in compliance with MC calculations since the discrepancies were also within 10% for head-and-neck and thoracic organs while they can reach ∼25%, again for pelvic organs. Conclusion: The parametric equation presents promising results and will be validated for other target sites as well as other facilities to go towards a universal method.« less

Proprioceptive influence on the optokinetic nystagmus.

PubMed

Botti, F; Anastasopoulos, D; Kostadima, V; Bambagioni, D; Pettorossi, V E

2001-01-01

The influence of neck and leg proprioceptive inputs on optokinetic-induced quick phases was studied in humans. Ten subjects received unidirectional horizontal optokinetic stimulation (10-20%/s) during sinusoidal neck, leg and combined neck + leg proprioceptive stimulation. The optokinetic reflex was measured by electro-oculography. Neck stimulation induced a shift in the nystagmus beating field in the opposite direction to body movement (gain 0.3 0.4, phase 140-180 degrees). The beating field shift resulted totally from the amplitude and frequency modulation of optokinetic quick phases, as slow phases were not affected. Leg proprioceptive stimulation induced a similar effect, but the phase of the response lagged by approximately 90 degrees compared with that of neck response. With combined neck + leg stimulation, the amplitude of the effect was a sum of the separate effects, but the phase coincided with that of the leg response. This suggests that neck and leg proprioceptive signals do not add linearly and that the leg signal determines the time of the response.

Comparison of adult and child radiation equivalent doses from 2 dental cone-beam computed tomography units.

PubMed

Al Najjar, Anas; Colosi, Dan; Dauer, Lawrence T; Prins, Robert; Patchell, Gayle; Branets, Iryna; Goren, Arthur D; Faber, Richard D

2013-06-01

With the advent of cone-beam computed tomography (CBCT) scans, there has been a transition toward these scans' replacing traditional radiographs for orthodontic diagnosis and treatment planning. Children represent a significant proportion of orthodontic patients. Similar CBCT exposure settings are predicted to result in higher equivalent doses to the head and neck organs in children than in adults. The purpose of this study was to measure the difference in equivalent organ doses from different scanners under similar settings in children compared with adults. Two phantom heads were used, representing a 33-year-old woman and a 5-year-old boy. Optically stimulated dosimeters were placed at 8 key head and neck organs, and equivalent doses to these organs were calculated after scanning. The manufacturers' predefined exposure settings were used. One scanner had a pediatric preset option; the other did not. Scanning the child's phantom head with the adult settings resulted in significantly higher equivalent radiation doses to children compared with adults, ranging from a 117% average ratio of equivalent dose to 341%. Readings at the cervical spine level were decreased significantly, down to 30% of the adult equivalent dose. When the pediatric preset was used for the scans, there was a decrease in the ratio of equivalent dose to the child mandible and thyroid. CBCT scans with adult settings on both phantom heads resulted in higher radiation doses to the head and neck organs in the child compared with the adult. In practice, this might result in excessive radiation to children scanned with default adult settings. Collimation should be used when possible to reduce the radiation dose to the patient. While CBCT scans offer a valuable tool, use of CBCT scans should be justified on a specific case-by-case basis. Copyright © 2013 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Treatment outcomes and feasibility of partial neck irradiation for patients with nasopharyngeal carcinoma with only retropharyngeal lymph node metastasis after intensity-modulated radiotherapy.

PubMed

Chen, Mo; Tang, Ling-Long; Sun, Ying; Mao, Yan-Ping; Li, Wen-Fei; Guo, Rui; Liu, Li-Zhi; Li, Li; Lin, Ai-Hua; Ma, Jun

2014-04-01

The purpose of this study was to summarize the treatment outcomes and evaluate the feasibility of partial neck irradiation in patients with nasopharyngeal carcinoma (NPC) with only retropharyngeal lymph nodes (RLNs) metastasis. Between January 2003 and December 2007, 54 patients with NPC who received partial neck irradiation to levels II, III, and VA and 100 patients who received whole neck irradiation were reviewed. The 5-year disease free survival (DFS), disease metastasis-free survival, (DMFS) local relapse-free survival (LRFS), and regional relapse-free survival (RRFS) rates were 81.8%, 87.7%, 94.8%, and 98.1%, respectively. The 5-year RRFS and DFS rates for the partial neck irradiation group and whole neck irradiation group were 98.1% versus 98.0% (p = .882), 87.0% vs 77.0% (p = .117), respectively. Partial neck irradiation was not considered a significant prognostic factor for any endpoint in univariate and multivariate analyses. Partial irradiation of neck levels II, III, and VA might be acceptable for patients with NPC with only RLN metastasis. Copyright © 2013 Wiley Periodicals, Inc.

Continuous-Course Reirradiation With Concurrent Carboplatin and Paclitaxel for Locally Recurrent, Nonmetastatic Squamous Cell Carcinoma of the Head-and-Neck

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

Kharofa, Jordan; Choong, Nicholas; Wang, Dian

Purpose: To examine the efficacy and toxicity of continuous-course, conformal reirradiation with weekly paclitaxel and carboplatin for the treatment of locally recurrent, nonmetastatic squamous cell carcinoma of the head and neck (SCCHN) in a previously irradiated field. Methods and Materials: Patients treated with continuous course-reirradiation with concurrent carboplatin and paclitaxel at the Medical College of Wisconsin and the Clement J. Zablocki VA from 2001 through 2009 were retrospectively reviewed. Patients included in the analysis had prior radiation at the site of recurrence of at least 45 Gy. The analysis included patients who received either intensity-modulated radiotherapy (RT) or three-dimensional conformalmore » RT techniques. All patients received weekly concurrent carboplatin (AUC2) and paclitaxel (30-50 mg/m{sup 2}). Results: Thirty-eight patients with nonmetastatic SCCHN met the entry criteria for analysis. The primary sites at initial diagnosis were oropharyngeal or laryngeal in most patients (66%). Median reirradiation dose was 60 Gy (range, 54-70 Gy). Acute toxicity included Grade 2 neutropenia (5%), Grade 3 neutropenia (15%), and Grade 1/2 thrombocytopenia (8%). No deaths occurred from hematologic toxicity. Chemotherapy doses held (50%) was more prevalent than radiation treatment break (8%). Sixty-eight percent of patients required a gastrostomy tube in follow-up. Significant late toxicity was experienced in 6 patients (16%): 1 tracheoesophageal fistula, 1 pharyngocutaneous fistula, 3 with osteoradionecrosis, and 1 patient with a lingual artery bleed. Patients treated with three-dimensional conformal RT had more frequent significant late toxicites than patients treated with intensity-modulated RT (44% and 7% respectively, p < 0.05). The median time to progression was 7 months and progression-free rates at 1, 2, and 5 years was 44%, 34%, and 29% respectively. The median overall survival was 16 months. Overall survival at 1, 3, and 5 years was 54%, 31%, and 20% respectively. Conclusions: Continuous-course, conformal reirradiation with weekly paclitaxel and carboplatin has an acceptable toxicity profile and offers a potentially curative option in a subset of patients with few other options.« less

Analysis of factors influencing the development of xerostomia during intensity-modulated radiotherapy.

PubMed

Randall, Ken; Stevens, Jason; Yepes, Juan Fernando; Randall, Marcus E; Kudrimoti, Mahesh; Feddock, Jonathan; Xi, Jing; Kryscio, Richard J; Miller, Craig S

2013-06-01

Factors influencing xerostomia during intensity-modulated radiation therapy (IMRT) were assessed. A 6-week study of 32 head and neck cancer (HNC) patients was performed. Subjects completed the Xerostomia Inventory (XI) and provided stimulated saliva (SS) at baseline, week 2 and at end of IMRT. Influence of SS flow rate (SSFR), calcium and mucin 5b (MUC5b) concentrations and radiation dose on xerostomia was determined. HNC subjects experienced mean SSFR decline of 36% by visit 2 (N = 27; P = .012) and 57% by visit 3 (N = 20; P = .0004). Concentrations of calcium and MUC5b increased, but not significantly during IMRT (P > .05). Xerostomia correlated most with decreasing salivary flow rate as determined by Spearman correlations (P < .04) and linear mixed models (P < .0001). Although IMRT is sparing to the parotid glands, it has an early effect on SSFR and the constituents in saliva in a manner that is associated with the perception of xerostomia. Copyright © 2013 Elsevier Inc. All rights reserved.

The feasibility of contralateral lower neck sparing intensity modulation radiated therapy for nasopharyngeal carcinoma patients with unilateral cervical lymph node involvement.

PubMed

Tang, Ling-Long; Tang, Xin-Ran; Li, Wen-Fei; Chen, Lei; Tian, Li; Lin, Ai-Hua; Sun, Ying; Ma, Jun

2017-06-01

To investigate the feasibility of contralateral lower neck sparing intensity modulation radiated therapy (IMRT) for nasopharyngeal carcinoma patients (NPC) with unilateral cervical lymph node metastasis. Retrospective review of 546 patients with unilateral cervical lymph node metastasis treated between November 2009 and February 2012 at one institution. All patients were staged using magnetic resonance imaging and received radical IMRT. Patients were classified into two groups: the inferior border of the negative neck irradiation field only covered Levels III to Va in Group 1; the inferior border covered entire neck down to Levels IV to Vb in Group 2. Median follow-up was 49.9months (range, 1.3-69.2months). Four-year overall survival (OS:89.3% vs. 88.9%, P=0.91), disease-free survival (DFS:81.7% vs. 81.0%, P=0.91), distant metastasis-free survival (DMFS:88.2% vs. 87.9%, P=0.95), local relapse-free survival (LRFS:96.7% vs. 94.7%, P=0.70) and nodal relapse-free survival (NRFS: 96.1% vs. 95.9%, P=0.94) were not significantly different between Group 1 and Group 2. Twenty-two patients developed cervical lymph node relapse; of whom 20/22 (91.0%) developed unilateral relapse within pretreatment positive neck. Only one patient developed out-of-field relapse, though this patient also relapsed within the neck irradiation field (Level II). No clinicopathological feature tested had significant prognostic value for NRFS in multivariate analysis. In the IMRT and MRI era, contralateral lower neck sparing IMRT seems to be feasible for NPC patients with unilateral cervical lymph node metastasis. Copyright © 2017. Published by Elsevier Ltd.

Interplay effect on a 6-MV flattening-filter-free linear accelerator with high dose rate and fast multi-leaf collimator motion treating breast and lung phantoms.

PubMed

Netherton, Tucker; Li, Yuting; Nitsch, Paige; Shaitelman, Simona; Balter, Peter; Gao, Song; Klopp, Ann; Muruganandham, Manickam; Court, Laurence

2018-06-01

Using a new linear accelerator with high dose rate (800 MU/min), fast MLC motions (5.0 cm/s), fast gantry rotation (15 s/rotation), and 1 cm wide MLCs, we aimed to quantify the effects of complexity, arc number, and fractionation on interplay for breast and lung treatments under target motion. To study lung interplay, eight VMAT plans (1-6 arcs) and four-nine-field sliding-window IMRT plans varying in complexity were created. For the breast plans, four-four-field sliding-window IMRT plans were created. Using the Halcyon 1.0 linear accelerator, each plan was delivered five times each under sinusoidal breathing motion to a phantom with 20 implanted MOSFET detectors; MOSFET dose (cGy), delivery time, and MU/cGy values were recorded. Maximum and mean dose deviations were calculated from MOSFET data. The number of MOSFETs with at least 19 of 20 detectors agreeing with their expected dose within 5% per fraction was calculated across 10 6 iterations to model dose deviation as function of fraction number for all plan variants. To put interplay plans into clinical context, additional IMRT and VMAT plans were created and delivered for the sites of head and neck, prostate, whole brain, breast, pelvis, and lung. Average modulation and interplay effect were compared to those from conventional linear accelerators, as reported from previous studies. The mean beam modulation for plans created for the Halcyon 1.0 linear accelerator was 2.9 MU/cGy (two- to four-field IMRT breast plans), 6.2 MU/cGy (at least five-field IMRT), and 3.6 MU/cGy (four-arc VMAT). To achieve treatment plan objectives, Halcyon 1.0 VMAT plans require more arcs and modulation than VMAT on conventional linear accelerators. Maximum and mean dose deviations increased with increasing plan complexity under tumor motion for breast and lung treatments. Concerning VMAT plans under motion, maximum, and mean dose deviations were higher for one arc than for two arcs regardless of plan complexity. For plan variants with maximum dose deviations greater than 3.7%, dose deviation as a function of fraction number was protracted. For treatments on the Halcyon 1.0 linear accelerator, the convergence of dose deviation with fraction number happened more slowly than reported for conventional linear accelerators. However, if plan complexity is reduced for IMRT and if tumor motion is less than ~10-mm, interplay is greatly reduced. To minimize dose deviations across multiple fractions for dynamic targets, we recommend limiting treatment plan complexity and avoiding one-arc VMAT on the Halcyon 1.0 linear accelerator when interplay is a concern. © 2018 American Association of Physicists in Medicine.

Moving Toward Bioadjuvant Approaches to Head and Neck Cancer Prevention

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

Saba, Nabil F.; Hammond, Anthea; Shin, Dong M.

2007-10-01

Head and neck squamous cell carcinoma affects >45,000 Americans annually. Patients who are successfully treated for their primary tumor are at high risk of developing a second primary tumor, making effective preventive strategies highly desirable for this disease. Although a landmark study in 1990 suggested some benefit of high-dose retinoids in head and neck cancer prevention, subsequent trials using more tolerable doses have shown limited clinical success. Newer preventive strategies have included bioadjuvant therapy combining retinoids with interferon and {alpha}-tocopherol, combinations of molecularly targeted agents, and oncolytic viruses. Furthermore, considerable evidence has supported a cancer protective role for several nutrients,more » including green tea and curcumin analogs. Natural compounds such as these with favorable long-term safety profiles might be particularly suited to the cancer prevention setting, in which patients will usually tolerate only moderate risk and toxicity.« less

Scattered dose to radiosensitive organs and associated risk for cancer development from head and neck radiotherapy in pediatric patients.

PubMed

Kourinou, Kalliopi M; Mazonakis, Michalis; Lyraraki, Efrosini; Stratakis, John; Damilakis, John

2013-11-01

The purpose of this study was to measure the scattered dose to out-of-field organs from head and neck radiotherapy in pediatric patients and to estimate the risk for second cancer induction to individual organs. Radiotherapy for thalamic tumor, brain tumor, acute leukemia and Hodgkin's disease in the neck region was simulated on 5 and 10-year-old pediatric phantoms with a 6 MV photon beam. The radiation dose to thyroid, breast, lung, stomach, ovaries, bladder, liver, uterus, prostate and colon was measured using thermoluminescent dosimeters. The methodology, provided by the BEIR VII report was used for the second cancer risk estimations. Peripheral dose range for a simulated 5-year-old patient was 0.019%-1.572% of the given tumor dose. The corresponding range at the advanced patient age was reduced to 0.018%-1.468%. The second cancer risk per fraction for male patients varied from 3 to 215 per 1,000,000 patients depending upon the age at the time of exposure, primary cancer site and organ scattered dose. The corresponding risk for females was 1-1186 per 1,000,000 patients. The higher risk values were found for breast, thyroid and lung cancer development. The current data concerning the risk magnitude for developing subsequent neoplasms to various out-of-field organs may be of value for health care professionals in the follow-up studies of childhood cancer survivors. Copyright © 2012 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Long periods with uninterrupted muscle activity related to neck and shoulder pain.

PubMed

Hanvold, Therese N; Wærsted, Morten; Veiersted, Kaj Bo

2012-01-01

The aim was to analyze the relationship between periods with uninterrupted neck muscle activity for ≥ 4 min and neck and shoulder pain. The trapezius muscle activity was recorded bilaterally on 40 young workers and students during a full shift. Neck and shoulder pain, mechanical work load and decision control were reported at the same time as the muscle activity recording and 6 months later. A dose-response relationship was found between uninterrupted muscle activity and neck and shoulder pain, with a ten-fold higher risk for the group with more than half, compared to less than a third, of the shift with uninterrupted muscle activity. Self-reported mechanical work load showed a small but protective effect related to pain. Gender and decision control did not emerge as important risk factors in this model. In conclusion, this study indicates that work or other exposures that contains long periods with uninterrupted neck muscle activity of 4 min duration or longer should be minimized to reduce risk of neck and shoulder pain.

Evaluating the Role of Prophylactic Gastrostomy Tube Placement Prior to Definitive Chemoradiotherapy for Head and Neck Cancer

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

Chen, Allen M., E-mail: allen.chen@ucdmc.ucdavis.ed; Li Baoqing; Lau, Derick H.

2010-11-15

Purpose: To determine the effect of prophylactic gastrostomy tube (GT) placement on acute and long-term outcome for patients treated with definitive chemoradiotherapy for locally advanced head and neck cancer. Methods and Materials: One hundred twenty consecutive patients were treated with chemoradiotherapy for Stage III/IV head and neck cancer to a median dose of 70 Gy (range, 64-74 Gy). The most common primary site was the oropharynx (66 patients). Sixty-seven patients (56%) were treated using intensity-modulated radiotherapy (IMRT). Seventy patients (58%) received prophylactic GT placement at the discretion of the physician before initiation of chemoradiotherapy. Results: Prophylactic GT placement significantly reducedmore » weight loss during radiation therapy from 43 pounds (range, 0 to 76 pounds) to 19 pounds (range, 0 to 51 pounds), which corresponded to a net change of -14% (range, 0% to -30%) and -8% (range, +1% to -22%) from baseline, respectively (p < 0.001). However, the proportion of patients who were GT-dependent at 6- and 12-months after treatment was 41% and 21%, respectively, compared with 8% and 0%, respectively, for those with and without prophylactic GT (p < 0.001). Additionally, prophylactic GT was associated with a significantly higher incidence of late esophageal stricture compared with those who did not have prophylactic GT (30% vs. 6%, p < 0.001). Conclusions: Although prophylactic GT placement was effective at preventing acute weight loss and the need for intravenous hydration, it was also associated with significantly higher rates of late esophageal toxicity. The benefits of this strategy must be balanced with the risks.« less

Submandibular gland-sparing radiation therapy for locally advanced oropharyngeal squamous cell carcinoma: patterns of failure and xerostomia outcomes.

PubMed

Gensheimer, Michael F; Liao, Jay J; Garden, Adam S; Laramore, George E; Parvathaneni, Upendra

2014-11-26

Saliva from submandibular glands (SMG) is necessary to minimize xerostomia. It is unclear whether SMG can be safely spared in patients undergoing bilateral neck radiotherapy for locally advanced oropharyngeal cancer without increasing the risk of marginal recurrence. We evaluated the outcomes of contralateral submandibular gland (cSMG) sparing intensity-modulated radiation therapy (IMRT). All patients with stage III/IV oropharyngeal squamous cell carcinoma treated with bilateral neck IMRT from 2006-2012 at our institution were included. Appropriately selected patients with favorable primary tumor characteristics and no definite contralateral neck disease were treated with cSMG-sparing IMRT. Patterns of failure and xerostomia outcomes were retrospectively analyzed. 114 patients were treated. 89% had stage IV disease and 89% received definitive radiation therapy. 76 patients (67%) received cSMG sparing IMRT. With a median follow-up of 30 months, there were 10 local, 9 regional, and 10 distant recurrences. 2-year overall survival was 86% and 2-year loco-regional control was 87%. In cSMG spared patients, the mean cSMG dose was 30.7 Gy. Late grade 2+ xerostomia was significantly reduced in the cSMG spared group compared to those without SMG sparing (6 months: 23% vs. 72%, 12 months: 6% vs. 41%, 24 months: 3% vs. 36%, all p < 0.0007). There were no peri-SMG marginal recurrences in the cSMG-spared cohort. cSMG sparing IMRT did not increase marginal failures in this series of locally advanced oropharyngeal SCC patients. Xerostomia was significantly reduced in cSMG spared patients.

Environmental tobacco smoking, mutagen sensitivity, and head and neck squamous cell carcinoma.

PubMed

Zhang, Z F; Morgenstern, H; Spitz, M R; Tashkin, D P; Yu, G P; Hsu, T C; Schantz, S P

2000-10-01

Although active tobacco smoking has been considered a major risk factor for head and neck cancer, few studies have evaluated environmental tobacco smoke (ETS) and its interaction with mutagen sensitivity on the risk of head and neck cancer. We investigated the relationship between ETS and head and neck cancer in a case-control study of 173 previously untreated cases with pathologically confirmed diagnoses of squamous cell carcinoma of the head and neck and 176 cancer-free controls at Memorial Sloan-Kettering Cancer Center between 1992 and 1994. A structured questionnaire was used to collect ETS exposure and other covariates including a history of active tobacco smoking and alcohol use. ETS measures include a history of ETS exposure at home and at workplace. The associations between passive smoking and head and neck cancer were analyzed by Mantel-Haenszel methods and logistic regression models. Additive and multiplicative models were used to evaluate effect modifications between ETS and mutagen sensitivity. The crude odds ratio (OR) for ETS exposure was 2.8 [95% confidence intervals (CI), 1.3-6.0]. Controlling for age, sex, race, education, alcohol consumption, pack-years of cigarette smoking, and marijuana use, the risk of squamous cell carcinoma of the head and neck was increased with ETS (adjusted OR, 2.4; 95% CI, 0.9-6.8). Dose-response relationships were observed for the degree of ETS exposure; the adjusted ORs were 2.1 (95% CI, 0.7-6.1) for those with moderate exposure and 3.6 (95% CI, 1.1-11.5) for individuals with heavy exposure (P for trend = 0.025), in comparison with those who never had ETS exposures. These associations and the dose-response relationships were still present when the analysis was restricted to nonactive smoking cases and controls (crude OR, 2.2; 95% CI, 0.6-8.4). Crude odds ratios were 1.8 for those with moderate ETS exposure and 4.3 for individuals with heavy ETS exposure among nonsmoking cases and controls (P for trend = 0.008). More than multiplicative interaction was suggested between passive smoking and mutagen sensitivity. This study suggests that ETS exposure may increase the risk of head and neck cancer with a dose-response pattern. Our analysis indicated that passive smoking may interact with mutagen sensitivity and other risk factors to increase the risk of head and neck cancer. Our results need to be interpreted with caution because of potential residual confounding effects of active tobacco smoking and other methodological limitations. Future large-scale studies are warranted to confirm our findings.

A multiscale filter for noise reduction of low-dose cone beam projections

NASA Astrophysics Data System (ADS)

Yao, Weiguang; Farr, Jonathan B.

2015-08-01

The Poisson or compound Poisson process governs the randomness of photon fluence in cone beam computed tomography (CBCT) imaging systems. The probability density function depends on the mean (noiseless) of the fluence at a certain detector. This dependence indicates the natural requirement of multiscale filters to smooth noise while preserving structures of the imaged object on the low-dose cone beam projection. In this work, we used a Gaussian filter, \\text{exp}≤ft(-{{x}2}/2σ f2\\right) as the multiscale filter to de-noise the low-dose cone beam projections. We analytically obtained the expression of {σf} , which represents the scale of the filter, by minimizing local noise-to-signal ratio. We analytically derived the variance of residual noise from the Poisson or compound Poisson processes after Gaussian filtering. From the derived analytical form of the variance of residual noise, optimal σ f2 is proved to be proportional to the noiseless fluence and modulated by local structure strength expressed as the linear fitting error of the structure. A strategy was used to obtain the reliable linear fitting error: smoothing the projection along the longitudinal direction to calculate the linear fitting error along the lateral direction and vice versa. The performance of our multiscale filter was examined on low-dose cone beam projections of a Catphan phantom and a head-and-neck patient. After performing the filter on the Catphan phantom projections scanned with pulse time 4 ms, the number of visible line pairs was similar to that scanned with 16 ms, and the contrast-to-noise ratio of the inserts was higher than that scanned with 16 ms about 64% in average. For the simulated head-and-neck patient projections with pulse time 4 ms, the visibility of soft tissue structures in the patient was comparable to that scanned with 20 ms. The image processing took less than 0.5 s per projection with 1024   ×   768 pixels.

Toward a web-based real-time radiation treatment planning system in a cloud computing environment.

PubMed

Na, Yong Hum; Suh, Tae-Suk; Kapp, Daniel S; Xing, Lei

2013-09-21

To exploit the potential dosimetric advantages of intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT), an in-depth approach is required to provide efficient computing methods. This needs to incorporate clinically related organ specific constraints, Monte Carlo (MC) dose calculations, and large-scale plan optimization. This paper describes our first steps toward a web-based real-time radiation treatment planning system in a cloud computing environment (CCE). The Amazon Elastic Compute Cloud (EC2) with a master node (named m2.xlarge containing 17.1 GB of memory, two virtual cores with 3.25 EC2 Compute Units each, 420 GB of instance storage, 64-bit platform) is used as the backbone of cloud computing for dose calculation and plan optimization. The master node is able to scale the workers on an 'on-demand' basis. MC dose calculation is employed to generate accurate beamlet dose kernels by parallel tasks. The intensity modulation optimization uses total-variation regularization (TVR) and generates piecewise constant fluence maps for each initial beam direction in a distributed manner over the CCE. The optimized fluence maps are segmented into deliverable apertures. The shape of each aperture is iteratively rectified to be a sequence of arcs using the manufacture's constraints. The output plan file from the EC2 is sent to the simple storage service. Three de-identified clinical cancer treatment plans have been studied for evaluating the performance of the new planning platform with 6 MV flattening filter free beams (40 × 40 cm(2)) from the Varian TrueBeam(TM) STx linear accelerator. A CCE leads to speed-ups of up to 14-fold for both dose kernel calculations and plan optimizations in the head and neck, lung, and prostate cancer cases considered in this study. The proposed system relies on a CCE that is able to provide an infrastructure for parallel and distributed computing. The resultant plans from the cloud computing are identical to PC-based IMRT and VMAT plans, confirming the reliability of the cloud computing platform. This cloud computing infrastructure has been established for a radiation treatment planning. It substantially improves the speed of inverse planning and makes future on-treatment adaptive re-planning possible.

Toward a web-based real-time radiation treatment planning system in a cloud computing environment

NASA Astrophysics Data System (ADS)

Hum Na, Yong; Suh, Tae-Suk; Kapp, Daniel S.; Xing, Lei

2013-09-01

To exploit the potential dosimetric advantages of intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT), an in-depth approach is required to provide efficient computing methods. This needs to incorporate clinically related organ specific constraints, Monte Carlo (MC) dose calculations, and large-scale plan optimization. This paper describes our first steps toward a web-based real-time radiation treatment planning system in a cloud computing environment (CCE). The Amazon Elastic Compute Cloud (EC2) with a master node (named m2.xlarge containing 17.1 GB of memory, two virtual cores with 3.25 EC2 Compute Units each, 420 GB of instance storage, 64-bit platform) is used as the backbone of cloud computing for dose calculation and plan optimization. The master node is able to scale the workers on an ‘on-demand’ basis. MC dose calculation is employed to generate accurate beamlet dose kernels by parallel tasks. The intensity modulation optimization uses total-variation regularization (TVR) and generates piecewise constant fluence maps for each initial beam direction in a distributed manner over the CCE. The optimized fluence maps are segmented into deliverable apertures. The shape of each aperture is iteratively rectified to be a sequence of arcs using the manufacture’s constraints. The output plan file from the EC2 is sent to the simple storage service. Three de-identified clinical cancer treatment plans have been studied for evaluating the performance of the new planning platform with 6 MV flattening filter free beams (40 × 40 cm2) from the Varian TrueBeamTM STx linear accelerator. A CCE leads to speed-ups of up to 14-fold for both dose kernel calculations and plan optimizations in the head and neck, lung, and prostate cancer cases considered in this study. The proposed system relies on a CCE that is able to provide an infrastructure for parallel and distributed computing. The resultant plans from the cloud computing are identical to PC-based IMRT and VMAT plans, confirming the reliability of the cloud computing platform. This cloud computing infrastructure has been established for a radiation treatment planning. It substantially improves the speed of inverse planning and makes future on-treatment adaptive re-planning possible.

Verification of intensity modulated radiation therapy beams using a tissue equivalent plastic scintillator dosimetry system

NASA Astrophysics Data System (ADS)

Petric, Martin Peter

This thesis describes the development and implementation of a novel method for the dosimetric verification of intensity modulated radiation therapy (IMRT) fields with several advantages over current techniques. Through the use of a tissue equivalent plastic scintillator sheet viewed by a charge-coupled device (CCD) camera, this method provides a truly tissue equivalent dosimetry system capable of efficiently and accurately performing field-by-field verification of IMRT plans. This work was motivated by an initial study comparing two IMRT treatment planning systems. The clinical functionality of BrainLAB's BrainSCAN and Varian's Helios IMRT treatment planning systems were compared in terms of implementation and commissioning, dose optimization, and plan assessment. Implementation and commissioning revealed differences in the beam data required to characterize the beam prior to use with the BrainSCAN system requiring higher resolution data compared to Helios. This difference was found to impact on the ability of the systems to accurately calculate dose for highly modulated fields, with BrainSCAN being more successful than Helios. The dose optimization and plan assessment comparisons revealed that while both systems use considerably different optimization algorithms and user-control interfaces, they are both capable of producing substantially equivalent dose plans. The extensive use of dosimetric verification techniques in the IMRT treatment planning comparison study motivated the development and implementation of a novel IMRT dosimetric verification system. The system consists of a water-filled phantom with a tissue equivalent plastic scintillator sheet built into the top surface. Scintillation light is reflected by a plastic mirror within the phantom towards a viewing window where it is captured using a CCD camera. Optical photon spread is removed using a micro-louvre optical collimator and by deconvolving a glare kernel from the raw images. Characterization of this new dosimetric verification system indicates excellent dose response and spatial linearity, high spatial resolution, and good signal uniformity and reproducibility. Dosimetric results from square fields, dynamic wedged fields, and a 7-field head and neck IMRT treatment plan indicate good agreement with film dosimetry distributions. Efficiency analysis of the system reveals a 50% reduction in time requirements for field-by-field verification of a 7-field IMRT treatment plan compared to film dosimetry.

Effects of radiotherapy on parotid salivary sialochemistry in head and neck cancer patients.

PubMed

Gupta, S C; Singla, Alok; Singh, Mangal; Thaliath, B Paul; Geeta, Jaiswal

2009-12-01

To determine the effects of high dose irradiation on parotid salivary sodium and pH concentration at subsequent duration of 1.5, 3 and 6 months following radiotherapy. Eighty parotid glands of head and neck cancer patients were irradiated with mean dose of 66 Gy. The stimulated parotid flow (PF) was collected by a cannulation of Stenson's duct followed by analysis of sodium (PF sodium) by Easylyte Sodium/Potassium auto analyzer and pH by litmus narrow band pH paper. A steep elevation of PF sodium was found in post-RT period after 1.5 months of starting RT followed by gradual increase up to 6 months and pH changed towards acidity. A high dose of 66 Gy causes irreversible damage to parotid salivary duct system.

Institutional experience of interstitial brachytherapy for head and neck cancer with a comparison of high- and low dose rate practice.

PubMed

Mohanti, Bidhu Kalyan; Sahai, Puja; Thakar, Alok; Sikka, Kapil; Bhasker, Suman; Sharma, Atul; Sharma, Seema; Bahadur, Sudhir

2014-01-01

To describe our institutional experience with high dose rate (HDR) interstitial brachytherapy (IBT) compared with previously reported results on the low dose rate (LDR) practice for head and neck cancer. Eighty-four patients with oral cavity (n=70) or oropharyngeal cancer (n=14) were treated with 192Ir HDR-IBT. Seventy-eight patients had stage I or II tumour. The patients treated with IBT alone (n=42) received 39-42 Gy/10-14 fractions (median=40 Gy/10 fractions). With respect to the combination therapy group (n=42), prescription dose comprised of 12-18 Gy/3-6 fractions (median=15 Gy/5 fractions) for IBT and 40-50 Gy/20-25 fractions (median=50 Gy/25 fractions) for external radiotherapy. Brachytherapy was given as 2 fractions per day 6 hours apart with 4 Gy per fraction for monotherapy and 3 Gy per fraction for combination therapy. Four patients were not evaluable in the analysis of outcome. The primary site relapse rates were 23.8% (10/42) and 68.4% (26/38) in patients treated with IBT alone and combination therapy, respectively (p<0.001). Salvage surgery was performed in 19 patients. The 5-year local control rate was estimated at 62% and the disease-free survival (DFS) rate at 52% for all patients. Local control with respect to T1 and T2 tumours was 84% and 42%, respectively. Our present series on HDR-IBT and the previous report on LDR-IBT for head and neck cancer demonstrated similar DFS rates at 5 years (52%). The rate of regional failure in node-negative patients was <20% in both of our series. HDR-IBT offers similar results to LDR-IBT for head and neck cancer.

Verification measurements and clinical evaluation of the iPlan RT Monte Carlo dose algorithm for 6 MV photon energy

NASA Astrophysics Data System (ADS)

Petoukhova, A. L.; van Wingerden, K.; Wiggenraad, R. G. J.; van de Vaart, P. J. M.; van Egmond, J.; Franken, E. M.; van Santvoort, J. P. C.

2010-08-01

This study presents data for verification of the iPlan RT Monte Carlo (MC) dose algorithm (BrainLAB, Feldkirchen, Germany). MC calculations were compared with pencil beam (PB) calculations and verification measurements in phantoms with lung-equivalent material, air cavities or bone-equivalent material to mimic head and neck and thorax and in an Alderson anthropomorphic phantom. Dosimetric accuracy of MC for the micro-multileaf collimator (MLC) simulation was tested in a homogeneous phantom. All measurements were performed using an ionization chamber and Kodak EDR2 films with Novalis 6 MV photon beams. Dose distributions measured with film and calculated with MC in the homogeneous phantom are in excellent agreement for oval, C and squiggle-shaped fields and for a clinical IMRT plan. For a field with completely closed MLC, MC is much closer to the experimental result than the PB calculations. For fields larger than the dimensions of the inhomogeneities the MC calculations show excellent agreement (within 3%/1 mm) with the experimental data. MC calculations in the anthropomorphic phantom show good agreement with measurements for conformal beam plans and reasonable agreement for dynamic conformal arc and IMRT plans. For 6 head and neck and 15 lung patients a comparison of the MC plan with the PB plan was performed. Our results demonstrate that MC is able to accurately predict the dose in the presence of inhomogeneities typical for head and neck and thorax regions with reasonable calculation times (5-20 min). Lateral electron transport was well reproduced in MC calculations. We are planning to implement MC calculations for head and neck and lung cancer patients.

Predictions of Leukemia Risks to Astronauts from Solar Particle Events

NASA Technical Reports Server (NTRS)

Cucinotta, F. A.; Atwell, W.; Kim, M. Y.; George, K. A.; Ponomarev, A.; Nikjoo, H.; Wilson, J. W.

2006-01-01

Leukemias consisting of acute and chronic myeloid leukemia and acute lymphatic lymphomas represent the earliest cancers that appear after radiation exposure, have a high lethality fraction, and make up a significant fraction of the overall fatal cancer risk from radiation for adults. Several considerations impact the recommendation of a preferred model for the estimation of leukemia risks from solar particle events (SPE's): The BEIR VII report recommends several changes to the method of calculation of leukemia risk compared to the methods recommended by the NCRP Report No. 132 including the preference of a mixture model with additive and multiplicative components in BEIR VII compared to the additive transfer model recommended by NCRP Report No. 132. Proton fluences and doses vary considerably across marrow regions because of the characteristic spectra of primary solar protons making the use of an average dose suspect. Previous estimates of bone marrow doses from SPE's have used an average body-shielding distribution for marrow based on the computerized anatomical man model (CAM). We have developed an 82-point body-shielding distribution that faithfully reproduces the mean and variance of SPE doses in the active marrow regions (head and neck, chest, abdomen, pelvis and thighs) allowing for more accurate estimation of linear- and quadratic-dose components of the marrow response. SPE's have differential dose-rates and a pseudo-quadratic dose response term is possible in the peak-flux period of an event. Also, the mechanistic basis for leukemia risk continues to improve allowing for improved strategies in choosing dose-rate modulation factors and radiation quality descriptors. We make comparisons of the various choices of the components in leukemia risk estimates in formulating our preferred model. A major finding is that leukemia could be the dominant risk to astronauts for a major solar particle event.

Case control study to assess the possibility of decrease the risk of osteoradionecrosis in relation to the dose of radiation absorbed by the jaw

PubMed Central

Carini, Fabrizio; Bucalo, Concetta; Saggese, Vito; Monai, Dario; Porcaro, Gianluca

2012-01-01

Summary Aims the assessment of the limit dose for the organs at risk in external radiotherapy is a fundamental step to guarantee an optimal risk-benefit ratio. The aim of this study was to assess, through contouring the single dental cavities, the absorbed radiation dose on irradiated alveolar bones during the treatment of cervico-facial tumours, so as to test the correlation between the absorbed dose of radiation at alveolar level and the level of individual surgical risk for osteonecrosis. Materials and methods we selected 45 out of 89 patients on the basis of different exclusion criteria. Nine of these patients showed evidence of osteoradionecrosis. The patients were treated either with 3D conformational radiation therapy (3D-CRT) or with intensity-modulated radiation therapy (IMRT), there after alveolar bones were contoured using computed axial tomography (CAT scans) carried out following oncological and dental treatment. The dose-volume histograms (DVH) were obtained on the basis of such data, which included those relating to the dental cavities in addition to those inherent to the tumours and the organs at risk. Results all patients, irrespective of type of treatment, received an average of 60 to 70 grays in 30/35 sittings. The patients treated with IMRT showed higher variation in absorbed radiation dose than those treated with 3D-CRT. The alveolar encirclement allowed the assessment of the absorbed radiation dose, and consequently it also allowed to assess the individual surgical risk for osteonecrosis in patients with head and neck tumours who underwent radiography treatment. Conclusions the study of DVH allows the assessment of limit dose and the detection of the areas at greater risk for osteoradionecrosis before dental surgery. PMID:23285316

Analysis of peripheral doses for base of tongue treatment by linear accelerator and helical TomoTherapy IMRT

PubMed Central

Lamba, Michael A. S.; Elson, Howard R.

2010-01-01

The purpose of this study was to compare the peripheral doses to various organs from a typical head and neck intensity‐modulated radiation therapy (IMRT) treatment delivered by linear accelerator (linac) and helical TomoTherapy. Multiple human CT data sets were used to segment critical structures and organs at risk, fused and adjusted to an anthropomorphic phantom. Eighteen contours were designated for thermoluminescent dosimeter (TLD) placement. Following the RTOG IMRT Protocol 0522, treatment of the primary tumor and involved nodes (PTV70) and subclinical disease sites (PTV56) was planned utilizing IMRT to 70 Gy and 56 Gy. Clinically acceptable treatment plans were produced for linac and TomoTherapy treatments. TLDs were placed and each treatment plan was delivered to the anthropomorphic phantom four times. Within 2.5 cm (one helical TomoTherapy field width) superior and inferior to the field edges, normal tissue doses were on average 45% lower using linear accelerator. Beyond 2.5 cm, the helical TomoTherapy normal tissue dose was an average of 52% lower. The majority of points proved to be statistically different using the Student's t‐test with p<0.05. Using one method of calculation, probability of a secondary malignancy was 5.88% for the linear accelerator and 4.08% for helical TomoTherapy. Helical TomoTherapy delivers more dose than a linac immediately above and below the treatment field, contributing to the higher peripheral doses adjacent to the field. At distances beyond one field width (where leakage is dominant), helical TomoTherapy doses are lower than linear accelerator doses. PACS number: 87.50.cm Dosimetry/exposure assessment

Study design and early result of a phase I study of SABR for early-stage glottic cancer.

PubMed

Yu, Tosol; Wee, Chan Woo; Choi, Noorie; Wu, Hong-Gyun; Kang, Hyun-Cheol; Park, Jong Min; Kim, Jung-In; Kim, Jin Ho; Kwon, Tack-Kyun; Chung, Eun-Jae

2018-05-14

Avoidance of organs at risk has become possible with advances in image-guided volumetric-modulated arc therapy (VMAT) techniques. This study was designed to evaluate the safety and feasibility of stereotactic ablative radiotherapy (SABR) for early stage glottic cancer. This report presents the preliminary result of the first and second dose level. Fraction size was increased from 3.5 gray (Gy) (total dose 59.5 Gy) to 9 Gy (total dose 45 Gy). Dose-limiting toxicities were defined as grade 3 or higher treatment-related toxicities. Voice outcome was assessed with electroglottography, and quality of life (QoL) was measured with the Head and Neck Cancer Inventory (HNCI). Seven patients received 59.5 Gy at 3.5 Gy per fraction as the first dose level, and five patients received 55 Gy at 5 Gy per fraction as the second dose level. None of the patients developed grade 3+ toxicity throughout a median follow-up of 17.5 months (range, 1.7-30.6 months). One patient in the second dose level recurred in the primary site at 4 months after radiotherapy (RT) and received total laryngectomy. The rest of participants were disease-free at locoregional and distant sites. Jitter, shimmer, mean phonation time, and noise-to-harmony ratio did not change significantly at 6 months after RT. HNCI scores between pretreatment and posttreatment were not significantly different (P = 0.221). This study revealed acceptable toxicity, voice outcome, and QoL in patients treated with hypofractionated VMAT of 3.5 Gy and 5 Gy per fraction. This phase I study is currently ongoing with a dose of 55 Gy in 11 fractions and 45 Gy in five fractions. 2b. Laryngoscope, 2018. © 2018 The American Laryngological, Rhinological and Otological Society, Inc.

Radiation dose reduction in soft tissue neck CT using adaptive statistical iterative reconstruction (ASIR).

PubMed

Vachha, Behroze; Brodoefel, Harald; Wilcox, Carol; Hackney, David B; Moonis, Gul

2013-12-01

To compare objective and subjective image quality in neck CT images acquired at different tube current-time products (275 mAs and 340 mAs) and reconstructed with filtered-back-projection (FBP) and adaptive statistical iterative reconstruction (ASIR). HIPAA-compliant study with IRB approval and waiver of informed consent. 66 consecutive patients were randomly assigned to undergo contrast-enhanced neck CT at a standard tube-current-time-product (340 mAs; n = 33) or reduced tube-current-time-product (275 mAs, n = 33). Data sets were reconstructed with FBP and 2 levels (30%, 40%) of ASIR-FBP blending at 340 mAs and 275 mAs. Two neuroradiologists assessed subjective image quality in a blinded and randomized manner. Volume CT dose index (CTDIvol), dose-length-product (DLP), effective dose, and objective image noise were recorded. Signal-to-noise ratio (SNR) was computed as mean attenuation in a region of interest in the sternocleidomastoid muscle divided by image noise. Compared with FBP, ASIR resulted in a reduction of image noise at both 340 mAs and 275 mAs. Reduction of tube current from 340 mAs to 275 mAs resulted in an increase in mean objective image noise (p=0.02) and a decrease in SNR (p = 0.03) when images were reconstructed with FBP. However, when the 275 mAs images were reconstructed using ASIR, the mean objective image noise and SNR were similar to those of the standard 340 mAs CT images reconstructed with FBP (p>0.05). Subjective image noise was ranked by both raters as either average or less-than-average irrespective of the tube current and iterative reconstruction technique. Adapting ASIR into neck CT protocols reduced effective dose by 17% without compromising image quality. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

LRIG1 modulates aggressiveness of head and neck cancers by regulating EGFR-MAPK-SPHK1 signaling and extracellular matrix remodeling.

PubMed

Sheu, J J-C; Lee, C-C; Hua, C-H; Li, C-I; Lai, M-T; Lee, S-C; Cheng, J; Chen, C-M; Chan, C; Chao, S C-C; Chen, J-Y; Chang, J-Y; Lee, C-H

2014-03-13

EGFR overexpression and chromosome 3p deletion are two frequent events in head and neck cancers. We previously mapped the smallest region of recurrent copy-number loss at 3p12.2-p14.1. LRIG1, a negative regulator of EGFR, was found at 3p14, and its copy-number loss correlated with poor clinical outcome. Inducible expression of LRIG1 in head and neck cancer TW01 cells, a line with low LRIG1 levels, suppressed cell proliferation in vitro and tumor growth in vivo. Gene expression profiling, quantitative RT-PCR, chromatin immunoprecipitation, and western blot analysis demonstrated that LRIG1 modulated extracellular matrix (ECM) remodeling and EGFR-MAPK-SPHK1 transduction pathway by suppressing expression of EGFR ligands/activators, MMPs and SPHK1. In addition, LRIG1 induction triggered cell morphology changes and integrin inactivation, which coupled with reduced SNAI2 expression. By contrast, knockdown of endogenous LRIG1 in TW06 cells, a line with normal LRIG1 levels, significantly enhanced cell proliferation, migration and invasiveness. Such tumor-promoting effects could be abolished by specific MAPK or SPHK1 inhibitors. Our data suggest LRIG1 as a tumor suppressor for head and neck cancers; LRIG1 downregulation in cancer cells enhances EGFR-MAPK-SPHK1 signaling and ECM remodeling activity, leading to malignant phenotypes of head and neck cancers.

A phase I report of paclitaxel dose escalation combined with a fixed dose of carboplatin in the treatment of head and neck carcinoma.

PubMed

Dunphy, F R; Boyd, J H; Kim, H J; Dunphy, C H; Harrison, B R; Dunleavy, T L; Rodriguez, J J; McDonough, E M; Minster, J R; Hilton, J G

1997-05-15

Standard therapy for advanced head and neck carcinoma is surgery and radiation, and the subsequent 5-year survival with this treatment has been less than 50%. New combined modality treatment strategies are being tested to improve survival. New chemotherapy combinations are being developed and administered simultaneously with, or sequenced with, radiation and surgery. This article reports the Phase I results of administering paclitaxel and carboplatin preoperatively. The authors' objective was to develop an outpatient chemotherapy that would downstage tumors and allow organ preservation with equal or improved survival as compared with standard therapy. Thirty-six patients with untreated Stage III/IV head and neck carcinoma were treated and were evaluable for toxicity. All patients had lesions that were measurable in perpendicular planes. A nonrandomized, Phase I design was used, according to which cohorts of patients were treated every 21 days with escalating doses of paclitaxel (150-265 mg/m2) given as a 3-hour infusion immediately preceding carboplatin. Premedication was used to avoid acute hypersensitivity reactions. Carboplatin was administered intravenously over 1 hour at a constant dose calculated with the Calvert formula (area under the curve, 7.5). The dose-limiting toxicities were neuropathy and thrombocytopenia at a paclitaxel dose of 265 mg/m2. Neutropenic fever was observed in 30% of patients at a paclitaxel dose of 250-265 mg/m2. Other observed adverse effects included pruritus, myalgia, arthralgia, alopecia, nausea, and vomiting. Toxicity was acceptable. The maximum tolerated dose of paclitaxel was 230 mg/m2 without hematopoietic growth factor, or 250 mg/m2 with hematopoietic growth factor, the carboplatin dose held constant, calculated at area under the curve of 7.5. Phase II studies of this combination are warranted in the treatment of these carcinomas.

Swallowing performance and tube feeding status in patients treated with parotid-sparing intensity-modulated radiotherapy for head and neck cancer.

PubMed

Roe, Justin W G; Carding, Paul N; Drinnan, Michael J; Harrington, Kevin J; Nutting, Christopher M

2016-04-01

The purpose of this prospective study was to evaluate the swallowing performance of patients with head and neck cancer treated with parotid-sparing intensity-modulated radiotherapy (IMRT). Sixty-two patients were recruited. Data were collected before and up to 12 months after treatment. Measures included the Performance Status Scale for head and neck cancer (PSS-HN Normalcy of Diet and Eating in Public subscales), tube feeding status, and 100 mL water swallow test (WST) volume and capacity scores. There was a significant reduction in PSS-HN and WST scores from baseline to 3 months (p < .001). Significant improvements were observed up to 12 months on the PSS-HN. Swallowing volume and capacity scores recovered but did not reach statistical significance. Tube feeding was not required in 47% of the patients. IMRT significantly impacts on swallowing performance, although there is a trend for improvement up to 12 months after treatment. Our data support a case-by-case approach to tube feeding. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1436-E1444, 2016. © 2015 Wiley Periodicals, Inc.

The Advantages of Collimator Optimization for Intensity Modulated Radiation Therapy

NASA Astrophysics Data System (ADS)

Doozan, Brian

The goal of this study was to improve dosimetry for pelvic, lung, head and neck, and other cancers sites with aspherical planning target volumes (PTV) using a new algorithm for collimator optimization for intensity modulated radiation therapy (IMRT) that minimizes the x-jaw gap (CAX) and the area of the jaws (CAA) for each treatment field. A retroactive study on the effects of collimator optimization of 20 patients was performed by comparing metric results for new collimator optimization techniques in Eclipse version 11.0. Keeping all other parameters equal, multiple plans are created using four collimator techniques: CA 0, all fields have collimators set to 0°, CAE, using the Eclipse collimator optimization, CAA, minimizing the area of the jaws around the PTV, and CAX, minimizing the x-jaw gap. The minimum area and the minimum x-jaw angles are found by evaluating each field beam's eye view of the PTV with ImageJ and finding the desired parameters with a custom script. The evaluation of the plans included the monitor units (MU), the maximum dose of the plan, the maximum dose to organs at risk (OAR), the conformity index (CI) and the number of fields that are calculated to split. Compared to the CA0 plans, the monitor units decreased on average by 6% for the CAX method with a p-value of 0.01 from an ANOVA test. The average maximum dose remained within 1.1% difference between all four methods with the lowest given by CAX. The maximum dose to the most at risk organ was best spared by the CAA method, which decreased by 0.62% compared to the CA0. Minimizing the x-jaws significantly reduced the number of split fields from 61 to 37. In every metric tested the CAX optimization produced comparable or superior results compared to the other three techniques. For aspherical PTVs, CAX on average reduced the number of split fields, lowered the maximum dose, minimized the dose to the surrounding OAR, and decreased the monitor units. This is achieved while maintaining the same control of the PTV.

SU-E-T-766: Treatment Planning Comparison Study On Two Different Multileaf Collimators Delivered with Volumetric Modulated Arc Therapy

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

Zhang, R; Xiaomei, F; Bai, W

2015-06-15

Purpose: To compare and evaluate the performance of two different multileaf collimators(MLCi2 and Agility) delivery with volumetric modulated arc therapy techniques. Methods: Treatment plans were graded four (Low, Moderate, Moderate-High and High complexity) accorrding to the complexity. This includes 1 Low complexity(brain metastasis), 2 Moderate complexity(Lung and Liver), 1 Moderate-High complexity(prostate) and 1 High complexity ( head and neck) cases. Total dose of 60 Gy was given for all the plans. All cases were desigined two VMAT plans, one with MLCi2(group A) and the other with Agility(group B). All plans were done on Elekta VMAT with Monaco treatment planning system.more » All plans were generated with 6 MV X-rays for both Plan A and Plan B. Plans were evaluated based on the ability to meet the dose volume histogram, radiation conformity index, estimated radiation delivery time, dose homogeneity index(HI) and monitor units(MU) needed to deliver the prescribed dose. Results: Plans of group B achieved the best HI (HI = 1.05 Vs. 1.06) at the Low complexity cases while plans of group A were slightly better at the high complexity cases (HI = 1.12 Vs. 1.14). Faster VMAT plan delivery with Agility than with MLCi2 as plan complexity increased (Low complexity:52s Vs.52s, Moderate complexity:58s Vs. 55s, Moderate-High complexity: 171s Vs.152s, High complexity : 326s Vs. 202s ), especially for the most complex paradigms delivered time can be decresed 38%. No Significant changes were observed between the group B and group A plans in terms of the healthy tissue mean dose and MU. Both plans respected the planning objective for all organs at risk. Conclusion: The study concludes that VMAT plans with the novel Agility MLC can significant decrease the delivering time at the high complexity cases, while a slight compromise in the dose homogeneity index should be noted. This work was supported by The Medical Science Foundation of The health department of Hebei Province (No. 20130253)« less

Parotid gland mean dose as a xerostomia predictor in low-dose domains.

PubMed

Gabryś, Hubert Szymon; Buettner, Florian; Sterzing, Florian; Hauswald, Henrik; Bangert, Mark

2017-09-01

Xerostomia is a common side effect of radiotherapy resulting from excessive irradiation of salivary glands. Typically, xerostomia is modeled by the mean dose-response characteristic of parotid glands and prevented by mean dose constraints to either contralateral or both parotid glands. The aim of this study was to investigate whether normal tissue complication probability (NTCP) models based on the mean radiation dose to parotid glands are suitable for the prediction of xerostomia in a highly conformal low-dose regime of modern intensity-modulated radiotherapy (IMRT) techniques. We present a retrospective analysis of 153 head and neck cancer patients treated with radiotherapy. The Lyman Kutcher Burman (LKB) model was used to evaluate predictive power of the parotid gland mean dose with respect to xerostomia at 6 and 12 months after the treatment. The predictive performance of the model was evaluated by receiver operating characteristic (ROC) curves and precision-recall (PR) curves. Average mean doses to ipsilateral and contralateral parotid glands were 25.4 Gy and 18.7 Gy, respectively. QUANTEC constraints were met in 74% of patients. Mild to severe (G1+) xerostomia prevalence at both 6 and 12 months was 67%. Moderate to severe (G2+) xerostomia prevalence at 6 and 12 months was 20% and 15%, respectively. G1 + xerostomia was predicted reasonably well with area under the ROC curve ranging from 0.69 to 0.76. The LKB model failed to provide reliable G2 + xerostomia predictions at both time points. Reduction of the mean dose to parotid glands below QUANTEC guidelines resulted in low G2 + xerostomia rates. In this dose domain, the mean dose models predicted G1 + xerostomia fairly well, however, failed to recognize patients at risk of G2 + xerostomia. There is a need for the development of more flexible models able to capture complexity of dose response in this dose regime.

SU-E-T-541: Bolus Effect of Thermoplastic Masks in IMRT and VMAT Head and Neck Treatments

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

Zhen, H; Nedzi, L; Chen, S

2014-06-01

Purpose: To quantitatively evaluate the bolus effect of thermoplalstic mask on patient skin dose during multi-field IMRT and VMAT treatment. Methods: The clinically approved target contours for five head and neck patients were deformably registered to an anthropomorphic Rando phantom. Two plans: Multifield IMRT plan with 7-9 beams and VMAT plan with 2-4 arcs were created for each patient following same dose constraints. 3mm skin was excluded from PTVs but not constrained during optimization. The prescription dose was 200-220 cGy/fraction. A thermoplastic head and shoulder mask was customized for the Rando phantom. Each plan was delivered to the phantom twicemore » with and without mask. During each delivery, two rectangular strips of EBT3 films (1cm x 6.8cm) were placed across the anterior upper and lower neck near PTVs to measure the surface dose. For consistency films were positioned at same locations for same patient. A total of 8 film strips were obtained for each patient. Film dose was calibrated in the range of 0-400cGy on the day of plan delivery. For dose comparison 3 regions of interests (ROIs) of 1×1 cm{sup 2} were selected at left, right and middle part of each film, resulting in 6 point doses at each plan delivery. Results: The films without mask show relatively uniform dose distribution while those with mask clearly show mesh pattern of mask, usually indicating an increase in skin dose. On average the increase in skin dose over all ROIs with mask was 31.9%(±14.8%) with a range of 11.4%- 58.4%. There is no statistically significant difference (p=0.44) between skin dose increase in VMAT (30.8%±15.3%) and IMRT delivery (33.0%±14.9%). Conclusion: Thermoplastic immobilization masks increase surface dose for HN patient by around 30%. The magnitude is comparable between multi-field IMRT and VMAT. Radiochromic EBT3 film serves as an effective tool to quantify bolus effect.« less

On the impact of improved dosimetric accuracy on head and neck high dose rate brachytherapy.

PubMed

Peppa, Vasiliki; Pappas, Eleftherios; Major, Tibor; Takácsi-Nagy, Zoltán; Pantelis, Evaggelos; Papagiannis, Panagiotis

2016-07-01

To study the effect of finite patient dimensions and tissue heterogeneities in head and neck high dose rate brachytherapy. The current practice of TG-43 dosimetry was compared to patient specific dosimetry obtained using Monte Carlo simulation for a sample of 22 patient plans. The dose distributions were compared in terms of percentage dose differences as well as differences in dose volume histogram and radiobiological indices for the target and organs at risk (mandible, parotids, skin, and spinal cord). Noticeable percentage differences exist between TG-43 and patient specific dosimetry, mainly at low dose points. Expressed as fractions of the planning aim dose, percentage differences are within 2% with a general TG-43 overestimation except for the spine. These differences are consistent resulting in statistically significant differences of dose volume histogram and radiobiology indices. Absolute differences of these indices are however small to warrant clinical importance in terms of tumor control or complication probabilities. The introduction of dosimetry methods characterized by improved accuracy is a valuable advancement. It does not appear however to influence dose prescription or call for amendment of clinical recommendations for the mobile tongue, base of tongue, and floor of mouth patient cohort of this study. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

LASSO NTCP predictors for the incidence of xerostomia in patients with head and neck squamous cell carcinoma and nasopharyngeal carcinoma

PubMed Central

Lee, Tsair-Fwu; Liou, Ming-Hsiang; Huang, Yu-Jie; Chao, Pei-Ju; Ting, Hui-Min; Lee, Hsiao-Yi

2014-01-01

To predict the incidence of moderate-to-severe patient-reported xerostomia among head and neck squamous cell carcinoma (HNSCC) and nasopharyngeal carcinoma (NPC) patients treated with intensity-modulated radiotherapy (IMRT). Multivariable normal tissue complication probability (NTCP) models were developed by using quality of life questionnaire datasets from 152 patients with HNSCC and 84 patients with NPC. The primary endpoint was defined as moderate-to-severe xerostomia after IMRT. The numbers of predictive factors for a multivariable logistic regression model were determined using the least absolute shrinkage and selection operator (LASSO) with bootstrapping technique. Four predictive models were achieved by LASSO with the smallest number of factors while preserving predictive value with higher AUC performance. For all models, the dosimetric factors for the mean dose given to the contralateral and ipsilateral parotid gland were selected as the most significant predictors. Followed by the different clinical and socio-economic factors being selected, namely age, financial status, T stage, and education for different models were chosen. The predicted incidence of xerostomia for HNSCC and NPC patients can be improved by using multivariable logistic regression models with LASSO technique. The predictive model developed in HNSCC cannot be generalized to NPC cohort treated with IMRT without validation and vice versa. PMID:25163814

Projections onto the Pareto surface in multicriteria radiation therapy optimization

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

Bokrantz, Rasmus, E-mail: bokrantz@kth.se, E-mail: rasmus.bokrantz@raysearchlabs.com; Miettinen, Kaisa

2015-10-15

Purpose: To eliminate or reduce the error to Pareto optimality that arises in Pareto surface navigation when the Pareto surface is approximated by a small number of plans. Methods: The authors propose to project the navigated plan onto the Pareto surface as a postprocessing step to the navigation. The projection attempts to find a Pareto optimal plan that is at least as good as or better than the initial navigated plan with respect to all objective functions. An augmented form of projection is also suggested where dose–volume histogram constraints are used to prevent that the projection causes a violation ofmore » some clinical goal. The projections were evaluated with respect to planning for intensity modulated radiation therapy delivered by step-and-shoot and sliding window and spot-scanned intensity modulated proton therapy. Retrospective plans were generated for a prostate and a head and neck case. Results: The projections led to improved dose conformity and better sparing of organs at risk (OARs) for all three delivery techniques and both patient cases. The mean dose to OARs decreased by 3.1 Gy on average for the unconstrained form of the projection and by 2.0 Gy on average when dose–volume histogram constraints were used. No consistent improvements in target homogeneity were observed. Conclusions: There are situations when Pareto navigation leaves room for improvement in OAR sparing and dose conformity, for example, if the approximation of the Pareto surface is coarse or the problem formulation has too permissive constraints. A projection onto the Pareto surface can identify an inaccurate Pareto surface representation and, if necessary, improve the quality of the navigated plan.« less

Investigating CT to CBCT image registration for head and neck proton therapy as a tool for daily dose recalculation

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

Landry, Guillaume, E-mail: g.landry@lmu.de; Nijhuis, Reinoud; Thieke, Christian

2015-03-15

Purpose: Intensity modulated proton therapy (IMPT) of head and neck (H and N) cancer patients may be improved by plan adaptation. The decision to adapt the treatment plan based on a dose recalculation on the current anatomy requires a diagnostic quality computed tomography (CT) scan of the patient. As gantry-mounted cone beam CT (CBCT) scanners are currently being offered by vendors, they may offer daily or weekly updates of patient anatomy. CBCT image quality may not be sufficient for accurate proton dose calculation and it is likely necessary to perform CBCT CT number correction. In this work, the authors investigatedmore » deformable image registration (DIR) of the planning CT (pCT) to the CBCT to generate a virtual CT (vCT) to be used for proton dose recalculation. Methods: Datasets of six H and N cancer patients undergoing photon intensity modulated radiation therapy were used in this study to validate the vCT approach. Each dataset contained a CBCT acquired within 3 days of a replanning CT (rpCT), in addition to a pCT. The pCT and rpCT were delineated by a physician. A Morphons algorithm was employed in this work to perform DIR of the pCT to CBCT following a rigid registration of the two images. The contours from the pCT were deformed using the vector field resulting from DIR to yield a contoured vCT. The DIR accuracy was evaluated with a scale invariant feature transform (SIFT) algorithm comparing automatically identified matching features between vCT and CBCT. The rpCT was used as reference for evaluation of the vCT. The vCT and rpCT CT numbers were converted to stopping power ratio and the water equivalent thickness (WET) was calculated. IMPT dose distributions from treatment plans optimized on the pCT were recalculated with a Monte Carlo algorithm on the rpCT and vCT for comparison in terms of gamma index, dose volume histogram (DVH) statistics as well as proton range. The DIR generated contours on the vCT were compared to physician-drawn contours on the rpCT. Results: The DIR accuracy was better than 1.4 mm according to the SIFT evaluation. The mean WET differences between vCT (pCT) and rpCT were below 1 mm (2.6 mm). The amount of voxels passing 3%/3 mm gamma criteria were above 95% for the vCT vs rpCT. When using the rpCT contour set to derive DVH statistics from dose distributions calculated on the rpCT and vCT the differences, expressed in terms of 30 fractions of 2 Gy, were within [−4, 2 Gy] for parotid glands (D{sub mean}), spinal cord (D{sub 2%}), brainstem (D{sub 2%}), and CTV (D{sub 95%}). When using DIR generated contours for the vCT, those differences ranged within [−8, 11 Gy]. Conclusions: In this work, the authors generated CBCT based stopping power distributions using DIR of the pCT to a CBCT scan. DIR accuracy was below 1.4 mm as evaluated by the SIFT algorithm. Dose distributions calculated on the vCT agreed well to those calculated on the rpCT when using gamma index evaluation as well as DVH statistics based on the same contours. The use of DIR generated contours introduced variability in DVH statistics.« less

Left atrial accessory appendages, diverticula, and left-sided septal pouch in multi-slice computed tomography. Association with atrial fibrillation and cerebrovascular accidents.

PubMed

Hołda, Mateusz K; Koziej, Mateusz; Wszołek, Karolina; Pawlik, Wiesław; Krawczyk-Ożóg, Agata; Sorysz, Danuta; Łoboda, Piotr; Kuźma, Katarzyna; Kuniewicz, Marcin; Lelakowski, Jacek; Dudek, Dariusz; Klimek-Piotrowska, Wiesława

2017-10-01

The aim of this study is to provide a morphometric description of the left-sided septal pouch (LSSP), left atrial accessory appendages, and diverticula using cardiac multi-slice computed tomography (MSCT) and to compare results between patient subgroups. Two hundred and ninety four patients (42.9% females) with a mean of 69.4±13.1years of age were investigated using MSCT. The presence of the LSSP, left atrial accessory appendages, and diverticula was evaluated. Multiple logistic regression analysis was performed to check whether the presence of additional left atrial structures is associated with increased risk of atrial fibrillation and cerebrovascular accidents. At least one additional left atrial structure was present in 51.7% of patients. A single LSSP, left atrial diverticulum, and accessory appendage were present in 35.7%, 16.0%, and 4.1% of patients, respectively. After adjusting for other risk factors via multiple logistic regression, patients with LSSP are more likely to have atrial fibrillation (OR=2.00, 95% CI=1.14-3.48, p=0.01). The presence of a LSSP was found to be associated with an increased risk of transient ischemic attack using multiple logistic regression analysis after adjustment for other risk factors (OR=3.88, 95% CI=1.10-13.69, p=0.03). In conclusion LSSPs, accessory appendages, and diverticula are highly prevalent anatomic structures within the left atrium, which could be easily identified by MSCT. The presence of LSSP is associated with increased risk for atrial fibrillation and transient ischemic attack. Copyright © 2017 Elsevier B.V. All rights reserved.

Application of 3D documentation and geometric reconstruction methods in traffic accident analysis: with high resolution surface scanning, radiological MSCT/MRI scanning and real data based animation.

PubMed

Buck, Ursula; Naether, Silvio; Braun, Marcel; Bolliger, Stephan; Friederich, Hans; Jackowski, Christian; Aghayev, Emin; Christe, Andreas; Vock, Peter; Dirnhofer, Richard; Thali, Michael J

2007-07-20

The examination of traffic accidents is daily routine in forensic medicine. An important question in the analysis of the victims of traffic accidents, for example in collisions between motor vehicles and pedestrians or cyclists, is the situation of the impact. Apart from forensic medical examinations (external examination and autopsy), three-dimensional technologies and methods are gaining importance in forensic investigations. Besides the post-mortem multi-slice computed tomography (MSCT) and magnetic resonance imaging (MRI) for the documentation and analysis of internal findings, highly precise 3D surface scanning is employed for the documentation of the external body findings and of injury-inflicting instruments. The correlation of injuries of the body to the injury-inflicting object and the accident mechanism are of great importance. The applied methods include documentation of the external and internal body and the involved vehicles and inflicting tools as well as the analysis of the acquired data. The body surface and the accident vehicles with their damages were digitized by 3D surface scanning. For the internal findings of the body, post-mortem MSCT and MRI were used. The analysis included the processing of the obtained data to 3D models, determination of the driving direction of the vehicle, correlation of injuries to the vehicle damages, geometric determination of the impact situation and evaluation of further findings of the accident. In the following article, the benefits of the 3D documentation and computer-assisted, drawn-to-scale 3D comparisons of the relevant injuries with the damages to the vehicle in the analysis of the course of accidents, especially with regard to the impact situation, are shown on two examined cases.

Adenoid cystic carcinoma of the head and neck treated by surgery with or without postoperative radiation therapy: Prognostic features of recurrence

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

Chen, Allen M.; Bucci, M. Kara; Weinberg, Vivian

2006-09-01

Purpose: This study sought to review a single-institution experience with the management of adenoid cystic carcinoma of the head and neck. Methods and Materials: Between 1960 and 2004, 140 patients with adenoid cystic carcinoma of the head and neck were treated with definitive surgery. Ninety patients (64%) received postoperative radiation to a median dose of 64 Gy (range, 54-71 Gy). Distribution of T stage was: 26% T1, 28% T2, 20% T3, and 26% T4. Seventy-eight patients (56%) had microscopically positive margins. Median follow-up was 66 months (range, 7-267 months). Results: The 5- and 10-year rate estimates of local control weremore » 88% and 77%, respectively. A Cox proportional hazards model identified T4 disease (p = 0.0001), perineural invasion (p = 0.008), omission of postoperative radiation (p = 0.007), and major nerve involvement (p = 0.02) as independent predictors of local recurrence. Radiation dose lower than 60 Gy (p = 0.0004), T4 disease (p 0.005), and major nerve involvement (p = 0.02) were predictors of local recurrence among those treated with surgery and postoperative radiation. The 10-year overall survival and distant metastasis-free survival were 64% and 66%, respectively. Conclusion: Combined-modality therapy with surgery followed by radiation to doses in excess of 60 Gy should be considered the standard of care for adenoid cystic carcinoma of the head and neck.« less

Travelling for treatment; does distance and deprivation affect travel for intensity-modulated radiotherapy in the rural setting for head and neck cancer?

PubMed

Cosway, B; Douglas, L; Armstrong, N; Robson, A

2017-06-01

NHS England has commissioned intensity-modulated radiotherapy for head and neck cancers from Newcastle hospitals for patients in North Cumbria. This study assessed whether travel distances affected the decision to travel to Newcastle (to receive intensity-modulated radiotherapy) or Carlisle (to receive conformal radiotherapy). All patients for whom the multidisciplinary team recommended intensity-modulated radiotherapy between December 2013 and January 2016 were included. Index of multiple deprivation scores and travel distances were calculated. Patients were also asked why they chose their treating centre. Sixty-nine patients were included in this study. There were no significant differences in travel distance (p = 0.53) or index of multiple deprivation scores (p = 0.47) between patients opting for treatment in Carlisle or Newcastle. However, 29 of the 33 patients gave travel distance as their main reason for not travelling for treatment. Quantitatively, travel distance and deprivation does not impact on whether patients accept intensity-modulated radiotherapy. However, patients say distance is a major barrier for access. Future research should explore how to reduce this.

Patterns of failure and survival in patients with nasopharyngeal carcinoma treated with intensity-modulated radiation therapy in Saudi Arabia.

PubMed

Maklad, Ahmed Marzouk; Bayoumi, Yasser; Senosy Hassan, Mohamed Abdalazez; Elawadi, AbuSaleh A; AlHussain, Hussain; Elyamany, Ashraf; Aldhahri, Saleh F; Al-Qahtani, Khalid Hussain; AlQahtani, Mubarak; Tunio, Mutahir A

2016-01-01

We aimed to investigate the patterns of failure (locoregional and distant metastasis), associated factors, and treatment outcomes in nasopharyngeal carcinoma patients treated with intensity-modulated radiation therapy (IMRT) combined with chemotherapy. From April 2006 to December 2011, 68 nasopharyngeal carcinoma patients were treated with IMRT and chemotherapy at our hospital. Median radiation doses delivered to gross tumor volume and positive neck nodes were 66-70 Gy, 63 Gy to clinical target volume, and 50.4-56 Gy to clinically negative neck. The clinical toxicities, patterns of failures, locoregional control, distant metastasis control, disease-free survival, and overall survival were observed. The median follow-up time was 52.2 months (range: 11-87 months). Epstein-Barr virus infection was positive in 63.2% of patients. Overall disease failure developed in 21 patients, of whom 85.8% belonged to stage III/IV disease. Among these, there were seven locoregional recurrences, three regional recurrences with distant metastases, and eleven distant metastases. The median interval from the date of diagnosis to failure was 26.5 months (range: 16-50 months). Six of ten (60%) locoregional recurrences were treated with reirradiation ± concurrent chemotherapy. The 5-year locoregional control, distant metastasis control, disease-free survival, and overall survival rates of whole cohort were 81.1%, 74.3%, 60.1%, and 73.4%, respectively. Cox regression analyses revealed that neoadjuvant chemotherapy, age, and Epstein-Barr virus were independent predictors for disease-free survival. Neoadjuvant chemotherapy followed by IMRT with or without chemotherapy improves the long-term survival of Saudi patients with nasopharyngeal carcinoma. Distant metastasis was the main pattern of treatment failure. Neoadjuvant chemotherapy, age, and Epstein-Barr virus status before IMRT were important independent prognostic factors.

Postradiation hypothyroidism in head and neck cancers: A Department of Veterans Affairs single-institution case-control dosimetry study.

PubMed

Lin, Alexander J; Zhang, Juying; Cho-Lim, Jennie; Inouye, Warren; Lee, Steve P

2018-03-23

We performed a case-control study to characterize the dose-volume relationship and other variables leading to hypothyroidism after head and neck (H&N) cancer radiation therapy (RT) in a homogenous Veterans Affairs (VA) population. All records of patients receiving RT for various H&N cancers at a single VA medical center between 2007 and 2013 (n = 143) were screened for post-RT thyroid stimulating hormone (TSH) levels (n = 77). The thyroid gland was contoured on each slice of the planning computed tomography scan when available (hypothyroid: n = 18; euthyroid > 2 years: n = 16), and dose-volume histograms based on physical dose and biologically equivalent dose (BED) were compared systematically to find the significant dose-volume thresholds that distinguish the patients who developed clinical hypothyroidism. Dosimetric and clinical variables were considered in univariate and multivariate analysis. Preirradiation prevalence of hypothyroidism was 8 of 143 (5.6%). After RT, 36 of 77 (47%) screened patients had abnormally high TSH, of which 22 of 36 (61%) had clinical hypothyroidism after 1.29 ± 0.99 years. The median follow-up durations were 3.3 years and 4.7 years for euthyroid and hypothyroid patients, respectively. Compared with the euthyroid cohort (n = 41), these hypothyroid patients displayed no significant difference in age, gender, primary tumor site, thyroid volume, hypertension, diabetes, or use of chemotherapy, surgery, or intensity-modulated radiation therapy (IMRT). They were more likely to have had stage 3 or 4 cancer than euthyroid patients (86.5% vs 73.2%, p = 0.01). The odds ratios of hypothyroidism for stage 3 + 4 cancers and V50Gy < 75% were 5.0 and 0.2, respectively (p < 0.05). Equivalent BED threshold of V75Gy 3  < 75% gave an odds ratio of 0.156 for developing hypothyroidism (p = 0.02). The prevalence of post-RT clinical hypothyroidism was relatively high for patients with H&N cancers and warrants routine surveillance, especially in those with higher stage malignancy. V50Gy < 75% may be a useful guideline to avoid hypothyroidism. We also show BED data which could be used for unconventionally fractionated schemes, and V75Gy 3  < 75% may be a useful guideline. Published by Elsevier Inc.

Dose-volume histogram analysis of brainstem necrosis in head and neck tumors treated using carbon-ion radiotherapy.

PubMed

Shirai, Katsuyuki; Fukata, Kyohei; Adachi, Akiko; Saitoh, Jun-Ichi; Musha, Atsushi; Abe, Takanori; Kanai, Tatsuaki; Kobayashi, Daijiro; Shigeta, Yuka; Yokoo, Satoshi; Chikamatsu, Kazuaki; Ohno, Tatsuya; Nakano, Takashi

2017-10-01

We aimed to evaluate the relationship between brainstem necrosis and dose-volume histograms in patients with head and neck tumors after carbon-ion radiotherapy. We evaluated 85 patients with head and neck tumors who underwent carbon-ion radiotherapy and were followed-up for ≥12months. Brainstem necrosis was evaluated using the Common Terminology Criteria for Adverse Events (version 4.0). The median follow-up was 24months, and four patients developed grade 1 brainstem necrosis, with 2-year and 3-year cumulative rates of 2.8% and 6.5%, respectively. Receiver operating characteristic curve analysis revealed the following significant cut-off values: a maximum brainstem dose of 48Gy (relative biological effectiveness [RBE]), D1cm 3 of 27Gy (RBE), V40Gy (RBE) of 0.1cm 3 , V30Gy (RBE) of 0.7cm 3 , and V20Gy (RBE) of 1.4cm 3 . Multivariate analysis revealed that V30Gy (RBE) was most significantly associated with brainstem necrosis. The 2-year cumulative rates were 33% and 0% for V30Gy (RBE) of ≥0.7cm 3 and <0.7cm 3 , respectively (p<0.001). The present study indicated that the dose constraints might help minimize brainstem necrosis after carbon-ion radiotherapy. Copyright © 2017 The Author(s). Published by Elsevier B.V. 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.

Marijuana use and increased risk of squamous cell carcinoma of the head and neck.

PubMed

Zhang, Z F; Morgenstern, H; Spitz, M R; Tashkin, D P; Yu, G P; Marshall, J R; Hsu, T C; Schantz, S P

1999-12-01

Marijuana is the most commonly used illegal drug in the United States. In some subcultures, it is widely perceived to be harmless. Although the carcinogenic properties of marijuana smoke are similar to those of tobacco, no epidemiological studies of the relationship between marijuana use and head and neck cancer have been published. The relationship between marijuana use and head and neck cancer was investigated by a case-control study of 173 previously untreated cases with pathologically confirmed diagnoses of squamous cell carcinoma of the head and neck and 176 cancer-free controls at Memorial Sloan-Kettering Cancer Center between 1992 and 1994. Epidemiological data were collected by using a structured questionnaire, which included history of tobacco smoking, alcohol use, and marijuana use. The associations between marijuana use and head and neck cancer were analyzed by Mantel-Haenszel methods and logistic regression models. Controlling for age, sex, race, education, alcohol consumption, pack-years of cigarette smoking, and passive smoking, the risk of squamous cell carcinoma of the head and neck was increased with marijuana use [odds ratio (OR) comparing ever with never users, 2.6; 95% confidence interval (CI), 1.1-6.6]. Dose-response relationships were observed for frequency of marijuana use/day (P for trend <0.05) and years of marijuana use (P for trend <0.05). These associations were stronger for subjects who were 55 years of age and younger (OR, 3.1; 95% CI, 1.0-9.7). Possible interaction effects of marijuana use were observed with cigarette smoking, mutagen sensitivity, and to a lesser extent, alcohol use. Our results suggest that marijuana use may increase the risk of head and neck cancer with a strong dose-response pattern. Our analysis indicated that marijuana use may interact with mutagen sensitivity and other risk factors to increase the risk of head and neck cancer. The results need to be interpreted with some caution in drawing causal inferences because of certain methodological limitations, especially with regard to interactions.

Automated IMRT planning with regional optimization using planning scripts

PubMed Central

Wong, Eugene; Bzdusek, Karl; Lock, Michael; Chen, Jeff Z.

2013-01-01

Intensity‐modulated radiation therapy (IMRT) has become a standard technique in radiation therapy for treating different types of cancers. Various class solutions have been developed for simple cases (e.g., localized prostate, whole breast) to generate IMRT plans efficiently. However, for more complex cases (e.g., head and neck, pelvic nodes), it can be time‐consuming for a planner to generate optimized IMRT plans. To generate optimal plans in these more complex cases which generally have multiple target volumes and organs at risk, it is often required to have additional IMRT optimization structures such as dose limiting ring structures, adjust beam geometry, select inverse planning objectives and associated weights, and additional IMRT objectives to reduce cold and hot spots in the dose distribution. These parameters are generally manually adjusted with a repeated trial and error approach during the optimization process. To improve IMRT planning efficiency in these more complex cases, an iterative method that incorporates some of these adjustment processes automatically in a planning script is designed, implemented, and validated. In particular, regional optimization has been implemented in an iterative way to reduce various hot or cold spots during the optimization process that begins with defining and automatic segmentation of hot and cold spots, introducing new objectives and their relative weights into inverse planning, and turn this into an iterative process with termination criteria. The method has been applied to three clinical sites: prostate with pelvic nodes, head and neck, and anal canal cancers, and has shown to reduce IMRT planning time significantly for clinical applications with improved plan quality. The IMRT planning scripts have been used for more than 500 clinical cases. PACS numbers: 87.55.D, 87.55.de PMID:23318393

Insulin-Like Growth Factor-1 Preserves Salivary Gland Function After Fractionated Radiation

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

Limesand, Kirsten H., E-mail: limesank@u.arizona.ed; Department of Nutritional Sciences, University of Arizona, Tucson, AZ; Avila, Jennifer L.

Purpose: Radiotherapy for head-and-neck cancer consists of fractionated radiation treatments that cause significant damage to salivary glands leading to chronic salivary gland dysfunction with only limited prevention and treatment options currently available. This study examines the feasibility of IGF-1 in preserving salivary gland function following a fractionated radiation treatment regimen in a pre-clinical model. Methods and Materials: Mice were exposed to fractionated radiation, and salivary gland function and histological analyses of structure, apoptosis, and proliferation were evaluated. Results: In this study, we report that treatment with fractionated doses of radiation results in a significant level of apoptotic cells in FVBmore » mice after each fraction, which is significantly decreased in transgenic mice expressing a constitutively active mutant of Akt1 (myr-Akt1). Salivary gland function is significantly reduced in FVB mice exposed to fractionated radiation; however, myr-Akt1 transgenic mice maintain salivary function under the same treatment conditions. Injection into FVB mice of recombinant insulin-like growth factor-1 (IGF-1), which activates endogenous Akt, suppressed acute apoptosis and preserved salivary gland function after fractionated doses of radiation 30 to 90 days after treatment. FVB mice exposed to fractionated radiation had significantly lower levels of proliferating cell nuclear antigen-positive salivary acinar cells 90 days after treatment, which correlated with a chronic loss of function. In contrast, FVB mice injected with IGF-1 before each radiation treatment exhibited acinar cell proliferation rates similar to those of untreated controls. Conclusion: These studies suggest that activation of IGF-1-mediated pathways before head-and-neck radiation could modulate radiation-induced salivary gland dysfunction and maintain glandular homeostasis.« less

Restudy of malformations of the internal auditory meatus, cochlear nerve canal and cochlear nerve.

PubMed

Li, Youjin; Yang, Jun; Liu, Jinfen; Wu, Hao

2015-07-01

The present study aims to restudy the correlation between the internal auditory meatus (IAM), the cochlear nerve canal (CNC), the cochlear nerve (CN) and inner ear malformations. In this retrospective study design, the abnormal diameter of the IAM, CNC and CN in patients with any kind of inner ear malformations was evaluated using multi-slice spiral computed tomography (MSCT) (37 patients) and magnetic resonance imaging (MRI) (18 patients). Of 37 MSCT-diagnosed patients, 2 had IAM atresia, 11 IAM stenosis, 22 enlarged IAM, and 2 normal IAM with an abnormal CN. MRI diagnoses of 18 patients revealed 8 cases of aplastic CN, 6 hypoplastic CN, and 4 normal CN. CNC stenosis was associated with CN hypoplasia (P < 0.001). Patients with absent or stenotic IAM had less CN development than those with normal or enlarged IAM (P = 0.001). We propose a modification of the existing classification systems with a view to distinguishing malformations of the IAM, CNC and CN.

The effect of Mepitel Film on acute radiation-induced skin reactions in head and neck cancer patients: a feasibility study.

PubMed

Wooding, Hayley; Yan, Jing; Yuan, Ling; Chyou, Te-Yu; Gao, Shanbao; Ward, Iain; Herst, Patries M

2018-01-01

Mepitel Film significantly decreases acute radiation-induced skin reactions in breast cancer patients. Here we investigated the feasibility of using Mepitel Film in head and neck cancer patients (ACTRN12614000932662). Out of a total of 36 head and neck cancer patients from New Zealand (NZ) (n = 24) and China (n = 12) recruited between June 2015 and December 2016, 33 patients complied with protocol. Of these, 11 NZ patients followed a management protocol; 11 NZ patients and 11 Chinese patients followed a prophylactic protocol. An area of the neck receiving a homogenous radiation dose of > 35 Gy was divided into two equal halves; one half was randomized to Film and the other to either Sorbolene cream (NZ) or Biafine cream (China). Skin reaction severity was measured by Radiation Induced Skin Reaction Assessment Scale and expanded Radiation Therapy Oncology Group toxicity criteria. Skin dose was measured by thermoluminescent dosimeters or gafchromic film. Film decreased overall skin reaction severity (combined Radiation Induced Skin Reaction Assessment Scale score) by 29% and moist desquamation rates by 37% in the Chinese cohort and by 27 and 28%, respectively in the NZ cohort. Mepitel Film did not affect head movements but did not adhere well to the skin, particularly in males with heavy beard stubble, and caused itchiness, particularly in Chinese patients. Mepitel Film reduced acute radiation-induced skin reactions in our head and neck cancer patients, particularly in patients without heavy stubble. Advances in knowledge: This is the first study to confirm the feasibility of using Mepitel Film in head and neck cancer patients.

Toward improved target conformity for two spot scanning proton therapy delivery systems using dynamic collimation

PubMed Central

Moignier, Alexandra; Gelover, Edgar; Smith, Blake R.; Wang, Dongxu; Flynn, Ryan T.; Kirk, Maura L.; Lin, Liyong; Solberg, Timothy D.; Lin, Alexander; Hyer, Daniel E.

2016-01-01

Purpose: To quantify improvement in target conformity in brain and head and neck tumor treatments resulting from the use of a dynamic collimation system (DCS) with two spot scanning proton therapy delivery systems (universal nozzle, UN, and dedicated nozzle, DN) with median spot sizes of 5.2 and 3.2 mm over a range of energies from 100 to 230 MeV. Methods: Uncollimated and collimated plans were calculated with both UN and DN beam models implemented within our in-house treatment planning system for five brain and ten head and neck datasets in patients previously treated with spot scanning proton therapy. The prescription dose and beam angles from the clinical plans were used for both the UN and DN plans. The average reduction of the mean dose to the 10-mm ring surrounding the target between the uncollimated and collimated plans was calculated for the UN and the DN. Target conformity was analyzed using the mean dose to 1-mm thickness rings surrounding the target at increasing distances ranging from 1 to 10 mm. Results: The average reductions of the 10-mm ring mean dose for the UN and DN plans were 13.7% (95% CI: 11.6%–15.7%; p < 0.0001) and 11.5% (95% CI: 9.5%–13.5%; p < 0.0001) across all brain cases and 7.1% (95% CI: 4.4%–9.8%; p < 0.001) and 6.3% (95% CI: 3.7%–9.0%; p < 0.001), respectively, across all head and neck cases. The collimated UN plans were either more conformal (all brain cases and 60% of the head and neck cases) than or equivalent (40% of the head and neck cases) to the uncollimated DN plans. The collimated DN plans offered the highest conformity. Conclusions: The DCS added either to the UN or DN improved the target conformity. The DCS may be of particular interest for sites with UN systems looking for a more economical solution than upgrading the nozzle to improve the target conformity of their spot scanning proton therapy system. PMID:26936726

Magnitude of Neck-Surface Vibration as an Estimate of Subglottal Pressure during Modulations of Vocal Effort and Intensity in Healthy Speakers

ERIC Educational Resources Information Center

McKenna, Victoria S.; Llico, Andres F.; Mehta, Daryush D.; Perkell, Joseph S.; Stepp, Cara E.

2017-01-01

Purpose: This study examined the relationship between the magnitude of neck-surface vibration (NSV[subscript Mag]; transduced with an accelerometer) and intraoral estimates of subglottal pressure (P'[subscript sg]) during variations in vocal effort at 3 intensity levels. Method: Twelve vocally healthy adults produced strings of /p?/ syllables in 3…

The threshold of hypothyroidism after radiation therapy for head and neck cancer: a retrospective analysis of 116 cases.

PubMed

Fujiwara, Masayuki; Kamikonya, Norihiko; Odawara, Soichi; Suzuki, Hitomi; Niwa, Yasue; Takada, Yasuhiro; Doi, Hiroshi; Terada, Tomonori; Uwa, Nobuhiro; Sagawa, Kosuke; Hirota, Shozo

2015-05-01

The purpose of the present study was to determine the risk factors for developing thyroid disorders based on a dose-volume histograms (DVHs) analysis. Data from a total of 116 consecutive patients undergoing 3D conformal radiation therapy for head and neck cancers was retrospectively evaluated. Radiation therapy was performed between April 2007 and December 2010. There were 108 males and 8 females included in the study. The median follow-up term was 24 months (range, 1-62 months). The thyroid function was evaluated by measuring thyroid-stimulating hormone (TSH) and free thyroxine (FT4) levels. The mean thyroid dose, and the volume of thyroid gland spared from doses ≥10, 20, 30 and 40 Gy (VS10, VS20, VS30 and VS40) were calculated for all patients. The thyroid dose and volume were calculated by the radiotherapy planning system (RTPS). The cumulative incidences of hypothyroidism were 21.1% and 36.4% at one year and two years, respectively, after the end of radiation therapy. In the DVH analyses, the patients who received a mean thyroid dose <30 Gy had a significantly lower incidence of hypothyroidism. The univariate analyses showed that the VS10, VS20, VS30 and VS40 were associated with the risk of hypothyroidism. Hypothyroidism was a relatively common type of late radiation-induced toxicity. A mean thyroid dose of 30 Gy may be a useful threshold for predicting the development of hypothyroidism after radiation therapy for head and neck cancers. © The Author 2015. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

High dose rate brachytherapy for oral cancer

PubMed Central

YamazakI, Hideya; Yoshida, Ken; Yoshioka, Yasuo; Shimizutani, Kimishige; Furukawa, Souhei; Koizumi, Masahiko; Ogawa, Kazuhiko

2013-01-01

Brachytherapy results in better dose distribution compared with other treatments because of steep dose reduction in the surrounding normal tissues. Excellent local control rates and acceptable side effects have been demonstrated with brachytherapy as a sole treatment modality, a postoperative method, and a method of reirradiation. Low-dose-rate (LDR) brachytherapy has been employed worldwide for its superior outcome. With the advent of technology, high-dose-rate (HDR) brachytherapy has enabled health care providers to avoid radiation exposure. This therapy has been used for treating many types of cancer such as gynecological cancer, breast cancer, and prostate cancer. However, LDR and pulsed-dose-rate interstitial brachytherapies have been mainstays for head and neck cancer. HDR brachytherapy has not become widely used in the radiotherapy community for treating head and neck cancer because of lack of experience and biological concerns. On the other hand, because HDR brachytherapy is less time-consuming, treatment can occasionally be administered on an outpatient basis. For the convenience and safety of patients and medical staff, HDR brachytherapy should be explored. To enhance the role of this therapy in treatment of head and neck lesions, we have reviewed its outcomes with oral cancer, including Phase I/II to Phase III studies, evaluating this technique in terms of safety and efficacy. In particular, our studies have shown that superficial tumors can be treated using a non-invasive mold technique on an outpatient basis without adverse reactions. The next generation of image-guided brachytherapy using HDR has been discussed. In conclusion, although concrete evidence is yet to be produced with a sophisticated study in a reproducible manner, HDR brachytherapy remains an important option for treatment of oral cancer. PMID:23179377

High dose rate brachytherapy for oral cancer.

PubMed

Yamazaki, Hideya; Yoshida, Ken; Yoshioka, Yasuo; Shimizutani, Kimishige; Furukawa, Souhei; Koizumi, Masahiko; Ogawa, Kazuhiko

2013-01-01

Brachytherapy results in better dose distribution compared with other treatments because of steep dose reduction in the surrounding normal tissues. Excellent local control rates and acceptable side effects have been demonstrated with brachytherapy as a sole treatment modality, a postoperative method, and a method of reirradiation. Low-dose-rate (LDR) brachytherapy has been employed worldwide for its superior outcome. With the advent of technology, high-dose-rate (HDR) brachytherapy has enabled health care providers to avoid radiation exposure. This therapy has been used for treating many types of cancer such as gynecological cancer, breast cancer, and prostate cancer. However, LDR and pulsed-dose-rate interstitial brachytherapies have been mainstays for head and neck cancer. HDR brachytherapy has not become widely used in the radiotherapy community for treating head and neck cancer because of lack of experience and biological concerns. On the other hand, because HDR brachytherapy is less time-consuming, treatment can occasionally be administered on an outpatient basis. For the convenience and safety of patients and medical staff, HDR brachytherapy should be explored. To enhance the role of this therapy in treatment of head and neck lesions, we have reviewed its outcomes with oral cancer, including Phase I/II to Phase III studies, evaluating this technique in terms of safety and efficacy. In particular, our studies have shown that superficial tumors can be treated using a non-invasive mold technique on an outpatient basis without adverse reactions. The next generation of image-guided brachytherapy using HDR has been discussed. In conclusion, although concrete evidence is yet to be produced with a sophisticated study in a reproducible manner, HDR brachytherapy remains an important option for treatment of oral cancer.

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

Comparison of three and four-field radiotherapy technique and the effect of laryngeal shield on vocal and spinal cord radiation dose in radiotherapy of non-laryngeal head and neck tumors

NASA Astrophysics Data System (ADS)

Pour, Noushin Hassan; Farajollahi, Alireza; Jamali, Masoud; Zeinali, Ahad; Jangjou, Amir Ghasemi

2018-03-01

Introduction: Due to the effect of radiation on both the tumor and the surrounding normal tissues, the side effects of radiation in normal tissues are expected. One of the important complications in the head and neck radiotherapy is the doses reached to the larynx and spinal cord of patients with non-laryngeal head and neck tumors. Materials and Methods: In this study, CT scan images of 25 patients with non-laryngeal tumors including; lymph nodes, tongue, oropharynx and nasopharynx were used. A three-field and a four-field treatment planning with and without laryngeal shield in 3D CRT technique were planned for each patient. Subsequently, the values of Dmin, Dmean, Dmax and Dose Volume Histogram from the treatment planning system and NTCP values of spinal cord and larynx were calculated with BIOPLAN and MATLAB software for all patients. Results: Statistical results showed that mean values of doses of larynx in both three and four-field methods were significantly different between with and without shield groups. Comparison of absorbed dose didn't show any difference between the three and four field methods (P>0.05). Using Shield, just the mean and minimum doses of spinal cord decreased in both three and four fields. The NTCP of the spinal cord and larynx by three and four-field methods with shield in the LKB and EUD models significantly are less than that of the three and four fields without shields, and in the four-field method NTCP of larynx is less than three radiation field. Conclusion: The results of this study indicate that there is no significant difference in doses reached to larynx and spinal cord between the treatments techniques, but laryngeal shield reduce dose and NTCP values in larynx considerably.

Normal tissue complication probability modeling of radiation-induced hypothyroidism after head-and-neck radiation therapy.

PubMed

Bakhshandeh, Mohsen; Hashemi, Bijan; Mahdavi, Seied Rabi Mehdi; Nikoofar, Alireza; Vasheghani, Maryam; Kazemnejad, Anoshirvan

2013-02-01

To determine the dose-response relationship of the thyroid for radiation-induced hypothyroidism in head-and-neck radiation therapy, according to 6 normal tissue complication probability models, and to find the best-fit parameters of the models. Sixty-five patients treated with primary or postoperative radiation therapy for various cancers in the head-and-neck region were prospectively evaluated. Patient serum samples (tri-iodothyronine, thyroxine, thyroid-stimulating hormone [TSH], free tri-iodothyronine, and free thyroxine) were measured before and at regular time intervals until 1 year after the completion of radiation therapy. Dose-volume histograms (DVHs) of the patients' thyroid gland were derived from their computed tomography (CT)-based treatment planning data. Hypothyroidism was defined as increased TSH (subclinical hypothyroidism) or increased TSH in combination with decreased free thyroxine and thyroxine (clinical hypothyroidism). Thyroid DVHs were converted to 2 Gy/fraction equivalent doses using the linear-quadratic formula with α/β = 3 Gy. The evaluated models included the following: Lyman with the DVH reduced to the equivalent uniform dose (EUD), known as LEUD; Logit-EUD; mean dose; relative seriality; individual critical volume; and population critical volume models. The parameters of the models were obtained by fitting the patients' data using a maximum likelihood analysis method. The goodness of fit of the models was determined by the 2-sample Kolmogorov-Smirnov test. Ranking of the models was made according to Akaike's information criterion. Twenty-nine patients (44.6%) experienced hypothyroidism. None of the models was rejected according to the evaluation of the goodness of fit. The mean dose model was ranked as the best model on the basis of its Akaike's information criterion value. The D(50) estimated from the models was approximately 44 Gy. The implemented normal tissue complication probability models showed a parallel architecture for the thyroid. The mean dose model can be used as the best model to describe the dose-response relationship for hypothyroidism complication. Copyright © 2013 Elsevier Inc. All rights reserved.

SU-E-J-92: On-Line Cone Beam CT Based Planning for Emergency and Palliative Radiation Therapy

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

Held, M; Morin, O; Pouliot, J

2014-06-01

Purpose: To evaluate and develop the feasibility of on-line cone beam CT based planning for emergency and palliative radiotherapy treatments. Methods: Subsequent to phantom studies, a case library of 28 clinical megavoltage cone beam CT (MVCBCT) was built to assess dose-planning accuracies on MVCBCT for all anatomical sites. A simple emergency treatment plan was created on the MVCBCT and copied to its reference CT. The agreement between the dose distributions of each image pair was evaluated by the mean dose difference of the dose volume and the gamma index of the central 2D axial plane. An array of popular urgentmore » and palliative cases was also evaluated for imaging component clearance and field-of-view. Results: The treatment cases were categorized into four groups (head and neck, thorax/spine, pelvis and extremities). Dose distributions for head and neck treatments were predicted accurately in all cases with a gamma index of >95% for 2% and 2 mm criteria. Thoracic spine treatments had a gamma index as low as 60% indicating a need for better uniformity correction and tissue density calibration. Small anatomy changes between CT and MVCBCT could contribute to local errors. Pelvis and sacral spine treatment cases had a gamma index between 90% and 98% for 3%/3 mm criteria. The limited FOV became an issue for large pelvis patients. Imaging clearance was difficult for cases where the tumor was positioned far off midline. Conclusion: The MVCBCT based dose planning and delivery approach is feasible in many treatment cases. Dose distributions for head and neck patients are unrestrictedly predictable. Some FOV restrictions apply to other treatment sites. Lung tissue is most challenging for accurate dose calculations given the current imaging filters and corrections. Additional clinical cases for extremities need to be included in the study to assess the full range of site-specific planning accuracies. This work is supported by Siemens.« less

Treatment planning and dosimetric comparison study on two different volumetric modulated arc therapy delivery techniques

PubMed Central

Kumar, S.A. Syam; Holla, Raghavendra; Sukumar, Prabakar; Padmanaban, Sriram; Vivekanandan, Nagarajan

2012-01-01

Aim To compare and evaluate the performance of two different volumetric modulated arc therapy delivery techniques. Background Volumetric modulated arc therapy is a novel technique that has recently been made available for clinical use. Planning and dosimetric comparison study was done for Elekta VMAT and Varian RapidArc for different treatment sites. Materials and methods Ten patients were selected for the planning comparison study. This includes 2 head and neck, 2 oesophagus, 1 bladder, 3 cervix and 2 rectum cases. Total dose of 50 Gy was given for all the plans. All plans were done for RapidArc using Eclipse and for Elekta VMAT with Monaco treatment planning system. All plans were generated with 6 MV X-rays for both RapidArc and Elekta VMAT. Plans were evaluated based on the ability to meet the dose volume histogram, dose homogeneity index, radiation conformity index, estimated radiation delivery time, integral dose and monitor units needed to deliver the prescribed dose. Results RapidArc plans achieved the best conformity (CI95% = 1.08 ± 0.07) while Elekta VMAT plans were slightly inferior (CI95% = 1.10 ± 0.05). The in-homogeneity in the PTV was highest with Elekta VMAT with HI equal to 0.12 ± 0.02 Gy when compared to RapidArc with 0.08 ± 0.03. Significant changes were observed between the RapidArc and Elekta VMAT plans in terms of the healthy tissue mean dose and integral dose. Elekta VMAT plans show a reduction in the healthy tissue mean dose (6.92 ± 2.90) Gy when compared to RapidArc (7.83 ± 3.31) Gy. The integral dose is found to be inferior with Elekta VMAT (11.50 ± 6.49) × 104 Gy cm3 when compared to RapidArc (13.11 ± 7.52) × 104 Gy cm3. Both Varian RapidArc and Elekta VMAT respected the planning objective for all organs at risk. Gamma analysis result for the pre-treatment quality assurance shows good agreement between the planned and delivered fluence for 3 mm DTA, 3% DD for all the evaluated points inside the PTV, for both VMAT and RapidArc techniques. Conclusion The study concludes that a variable gantry speed with variable dose rate is important for efficient arc therapy delivery. RapidArc presents a slight improvement in the OAR sparing with better target coverage when compared to Elekta VMAT. Trivial differences were noted in all the plans for organ at risk but the two techniques provided satisfactory conformal avoidance and conformation. PMID:24416535

Dosimetric evaluation of the effect of dental implants in head and neck radiotherapy.

PubMed

Ozen, Julide; Dirican, Bahar; Oysul, Kaan; Beyzadeoglu, Murat; Ucok, Ozlem; Beydemir, Bedri

2005-06-01

The aim of the study was to examine the dose enhancement from scattered radiation at bone-dental implant interfaces during simulated head and neck radiotherapy. Four cylindrical titanium dental implants with 3 different sizes and lengths were implanted into a human mandible in 4 different positions. Ionization measurements for 6 MV X, 25 MV X, and Co-60 gamma rays were done. Thermoluminescent dosimeter (TLD 100 ) chips were used to measure radiation dose enhancement due to the scattered electrons from titanium and electronic disequilibrium at the tissue-metal interface. The results showed that for Co-60, there is a 21% maximum increase in dose to alveolar mandibular bone at the close proximity to the titanium. For 6-MV x-rays the dose enhancement increase was almost the same or slightly lower than for Co-60, while for 25-MV high-energy x-rays, dose enhancement was lower than that of others. This increase in dose enhancement fell off rapidly and became insignificant at 2 mm from the interface. Total dose that may lead to osteoradionecrosis risk of the mandible is slightly but not significantly affected by the scattered dose of the dental implants of lower jaw in the radiation field exposed to 3 different radiation beams.

SU-F-T-229: A Novel Method for EPID-Based In-Vivo Exit Dose Verification for Intensity Modulated Radiotherapy

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

Wu, Z; Wang, J; Peng, J

Purpose: Electronic portal imaging device (EPID) can be used to acquire a two-dimensional exit dose distribution during treatment delivery, thus allowing the in-vivo verification of the dose delivery through a comparison of measured portal images to predicted portal dose images (PDI). The aim of this study was to present a novel method to easily and accurately predict PDI, and to establish an EPID-based in-vivo dose verification method during IMRT treatments. Methods: We developed a model to determine the predicted portal dose at the same plane of the EPID detector location. The Varian EPID (aS1000) positions at 150cm source-to-detector-distance (SDD), andmore » can be used to acquire in-vivo exit dose using Portal Dosimetry (PD) function. Our model was generated to make an equivalent water thickness represent the buildup plate of EPID. The exit dose at extend SDD plane with patient CT data in the beam can be calculated as the predicted PDI in the treatment planning system (TPS). After that, the PDI was converted to the fluence at SDD of 150cm using the inverse square law coded in MATLAB. Five head-and-neck and prostate IMRT patient plans contain 32 fields were investigated to evaluate the feasibility of this new method. The measured EPID image was compared with PDI using the gamma analysis. Results: The average results for cumulative dose comparison were 81.9% and 91.6% for 3%, 3mm and 4%, 4mm gamma criteria, respectively. Results indicate that the patient transit dosimetry predicted algorithm compares well with EPID measured PD doses for test situations. Conclusion: Our new method can be used as an easy and feasible tool for online EPID-based in-vivo dose delivery verification for IMRT treatments. It can be implemented for fast detecting those obvious treatment delivery errors for individual field and patient quality assurance.« less

Dosimetric measurement of scattered radiation from dental implants in simulated head and neck radiotherapy.

PubMed

Wang, R; Pillai, K; Jones, P K

1998-01-01

The purpose of this study was to examine the dose enhancement at bone-implant interfaces from scattered radiation during simulated head and neck radiotherapy. Three cylindric implant systems with different compositions (pure titanium, titanium-aluminum-vanadium alloy, titanium coated with hydroxyapatite) and a high gold content transmandibular implant system (gold-copper-silver alloy) were studied. Extruded lithium fluoride single crystal chips were used as thermoluminescent material to measure radiation dose enhancement at 0, 1, and 2 mm from the bone-implant interface. The relative doses in buccal, lingual, mesial, and distal directions were also recorded and compared. The results indicated that the highest dose enhancement occurred at a distance of 0 mm from the bone-implant interface for all the implant systems studied. The transmandibular implants had higher scattered radiation than other groups at 0 mm and at 1 mm from the bone-implant interface. There was no significant difference of dose enhancement between buccal, lingual, mesial, and distal directions. Titanium implants coated with hydroxyapatite demonstrated the best results under the simulated irradiation.

High-Dose Recombinant Interferon Alfa-2B, Ipilimumab, or Pembrolizumab in Treating Patients With Stage III-IV High Risk Melanoma That Has Been Removed by Surgery

ClinicalTrials.gov

2018-06-18

Metastatic Non-Cutaneous Melanoma; Non-Cutaneous Melanoma; Recurrent Melanoma of the Skin; Recurrent Non-Cutaneous Melanoma; Stage III Cutaneous Melanoma AJCC v7; Stage III Mucosal Melanoma of the Head and Neck AJCC v7; Stage IIIA Cutaneous Melanoma AJCC v7; Stage IIIB Cutaneous Melanoma AJCC v7; Stage IIIC Cutaneous Melanoma AJCC v7; Stage IV Cutaneous Melanoma AJCC v6 and v7; Stage IVA Mucosal Melanoma of the Head and Neck AJCC v7; Stage IVB Mucosal Melanoma of the Head and Neck AJCC v7; Stage IVC Mucosal Melanoma of the Head and Neck AJCC v7

[Volume changes to the neck lymph node metastases in head-neck tumors. The evaluation of radiotherapeutic treatment success].

PubMed

Liszka, G; Thalacker, U; Somogyi, A; Németh, G

1997-08-01

This work is engaged with the volume change of neck lymph node metastasis of malignant tumors in the head-neck region during radiotherapy. In 54 patients with head and neck tumors, the volume of neck lymph nodes before and after radiation was measured. The volumetry was done with CT planimetry. The total dose was 66 Gy (2 Gy/d) telecobalt from 2 lateral opponated fields. The time of volume change could be defined with measuring of the half-time and the doubling-time by the help of Schwartz formula. After 10 Gy the volume diminution was about 20% and half-time 24 to 26 days. Afterwards the time of volume diminution picked up speed and finally achieved 60 to 72%. Meanwhile the half-time decreased to the half value. The result was independent of the site of primary tumor, the patient's sex and age. In our opinion the effectivity of radiotherapy can best be judged with defining of the volume change of lymph nodes of the neck.

Neutron therapy in Saudi Arabia: an overview and results of dose searching study in head and neck cancer.

PubMed

el-Akkad, S; Schultz, H P; Ahmad, K; Clubb, B; McArthur, P; Dobson, H; DeVol, E

1992-01-01

The King Faisal Specialist Hospital and Research Centre is the only center in the Middle East that incorporates a neutron therapy facility. The neutron beam is produced by a cyclotron, which produces a beam by either a (d(15)+Be) or (p(26)+Be) reaction. The beam from the proton reaction is selected for therapy because of its superior physical characteristics. These were verified by an intercomparison conducted by the European Organization for Research on Treatment of Cancer (EORTC) Heavy Particle Therapy Group. Full beam data are presented. The first study in the neutron therapy Program is on the treatment of squamous cancers of the head and neck. This consists of two parts. Part I is a dose searching phase and Part II is a comparison of our current photon treatment versus neutrons using the neutron dose selected by Part I of the study. Results of the dose searching phase (Part I) are presented.

Neck pain combined with arm pain among professional drivers of forest machines and the association with whole-body vibration exposure.

PubMed

Rehn, B; Nilsson, T; Lundström, R; Hagberg, M; Burström, L

2009-10-01

The purpose of this study was to investigate the existence of neck pain and arm pain among professional forest machine drivers and to find out if pain were related to their whole-body vibration (WBV) exposure. A self-administered questionnaire was sent to 529 forest machine drivers in northern Sweden and the response was 63%. Two pain groups were formed; 1) neck pain; 2) neck pain combined with arm pain. From WBV exposure data (recent measurements made according to ISO 2631-1, available information from reports) and from the self-administered questionnaire, 14 various WBV exposure/dose measures were calculated for each driver. The prevalence of neck pain reported both for the previous 12 months and for the previous 7 d was 34% and more than half of them reported neck pain combined with pain in one or both arms. Analysis showed no significant association between neck pain and high WBV exposure; however, cases with neck pain more often experienced shocks and jolts in the vehicle as uncomfortable. There was no significant association between the 14 WBV measures and type of neck pain (neck pain vs. neck pain combined with arm pain). It seems as if characteristics of WBV exposure can explain neither existence nor the type of neck pain amongst professional drivers of forest machines. The logging industry is important for several industrialised countries. Drivers of forest machines frequently report neuromusculoskeletal pain from the neck. The type of neck pain is important for the decision of treatment modality and may be associated with exposure characteristics at work.

The threshold of hypothyroidism after radiation therapy for head and neck cancer: a retrospective analysis of 116 cases

PubMed Central

Fujiwara, Masayuki; Kamikonya, Norihiko; Odawara, Soichi; Suzuki, Hitomi; Niwa, Yasue; Takada, Yasuhiro; Doi, Hiroshi; Terada, Tomonori; Uwa, Nobuhiro; Sagawa, Kosuke; Hirota, Shozo

2015-01-01

The purpose of the present study was to determine the risk factors for developing thyroid disorders based on a dose–volume histograms (DVHs) analysis. Data from a total of 116 consecutive patients undergoing 3D conformal radiation therapy for head and neck cancers was retrospectively evaluated. Radiation therapy was performed between April 2007 and December 2010. There were 108 males and 8 females included in the study. The median follow-up term was 24 months (range, 1–62 months). The thyroid function was evaluated by measuring thyroid-stimulating hormone (TSH) and free thyroxine (FT4) levels. The mean thyroid dose, and the volume of thyroid gland spared from doses ≥10, 20, 30 and 40 Gy (VS10, VS20, VS30 and VS40) were calculated for all patients. The thyroid dose and volume were calculated by the radiotherapy planning system (RTPS). The cumulative incidences of hypothyroidism were 21.1% and 36.4% at one year and two years, respectively, after the end of radiation therapy. In the DVH analyses, the patients who received a mean thyroid dose <30 Gy had a significantly lower incidence of hypothyroidism. The univariate analyses showed that the VS10, VS20, VS30 and VS40 were associated with the risk of hypothyroidism. Hypothyroidism was a relatively common type of late radiation-induced toxicity. A mean thyroid dose of 30 Gy may be a useful threshold for predicting the development of hypothyroidism after radiation therapy for head and neck cancers. PMID:25818629

The Evolution of and Risk Factors for Neck Muscle Atrophy and Weakness in Nasopharyngeal Carcinoma Treated With Intensity-Modulated Radiotherapy

PubMed Central

Zhang, Lu-Lu; Mao, Yan-Ping; Zhou, Guan-Qun; Tang, Ling-Long; Qi, Zhen-Yu; Lin, Li; Yao, Ji-Jin; Ma, Jun; Lin, Ai-Hua; Sun, Ying

2015-01-01

Abstract The aim of this study was to investigate the evolution of sternocleidomastoid muscle (SCM) atrophy in nasopharyngeal carcinoma (NPC) patients following intensity-modulated radiotherapy (IMRT), and the relationship between SCM atrophy and neck weakness. Data were retrospectively analyzed from 223 biopsy-proven NPC patients with no distant metastasis who underwent IMRT with or without chemotherapy. The volume of SCM was measured on pretreatment magnetic resonance imaging (MRI), and MRIs were conducted 1, 2, and 3 years after the completion of IMRT. Change in SCM volume was calculated and classified using the late effects of normal tissues–subjective, objective, management, and analytic system. The grade of neck muscle weakness, classified by the Common Terminology Criteria for Adverse Events V 3.0, was measured 3 years after the completion of IMRT. The average SCM atrophy ratio was −10.97%, −18.65%, and −22.25% at 1, 2, and 3 years postirradiation, respectively. Multivariate analysis indicated N stage and the length of time after IMRT were independent prognostic variables. There were significant associations between the degree of SCM atrophy and neck weakness. Radical IMRT can cause significant SCM atrophy in NPC patients. A more advanced N stage was associated with more severe SCM atrophy, but no difference was observed between N2 and N3. SCM atrophy progresses over time during the 3 years following IMRT. Grade of SCM atrophy is significantly associated with neck weakness. PMID:26252307