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Sample records for 4d ct acquisition

  1. Actively triggered 4d cone-beam CT acquisition

    SciTech Connect

    Fast, Martin F.; Wisotzky, Eric; Oelfke, Uwe; Nill, Simeon

    2013-09-15

    Purpose: 4d cone-beam computed tomography (CBCT) scans are usually reconstructed by extracting the motion information from the 2d projections or an external surrogate signal, and binning the individual projections into multiple respiratory phases. In this “after-the-fact” binning approach, however, projections are unevenly distributed over respiratory phases resulting in inefficient utilization of imaging dose. To avoid excess dose in certain respiratory phases, and poor image quality due to a lack of projections in others, the authors have developed a novel 4d CBCT acquisition framework which actively triggers 2d projections based on the forward-predicted position of the tumor.Methods: The forward-prediction of the tumor position was independently established using either (i) an electromagnetic (EM) tracking system based on implanted EM-transponders which act as a surrogate for the tumor position, or (ii) an external motion sensor measuring the chest-wall displacement and correlating this external motion to the phase-shifted diaphragm motion derived from the acquired images. In order to avoid EM-induced artifacts in the imaging detector, the authors devised a simple but effective “Faraday” shielding cage. The authors demonstrated the feasibility of their acquisition strategy by scanning an anthropomorphic lung phantom moving on 1d or 2d sinusoidal trajectories.Results: With both tumor position devices, the authors were able to acquire 4d CBCTs free of motion blurring. For scans based on the EM tracking system, reconstruction artifacts stemming from the presence of the EM-array and the EM-transponders were greatly reduced using newly developed correction algorithms. By tuning the imaging frequency independently for each respiratory phase prior to acquisition, it was possible to harmonize the number of projections over respiratory phases. Depending on the breathing period (3.5 or 5 s) and the gantry rotation time (4 or 5 min), between ∼90 and 145

  2. Respiratory regularity gated 4D CT acquisition: concepts and proof of principle.

    PubMed

    Keall, P J; Vedam, S S; George, R; Williamson, J F

    2007-09-01

    Four-dimensional CT images are generally sorted through a post-acquisition procedure correlating images with a time-synchronized external respiration signal. The patient's ability to maintain reproducible respiration is the limiting factor during 4D CT, where artifacts occur in approximately 85% of scans with current technology. To reduce these artifacts and their subsequent effects during radiotherapy planning, a method for improved 4D CT image acquisition that relies on gating 4D CT acquisition based on the real time monitoring of the respiration signal has been proposed. The respiration signal and CT data acquisition are linked, such that data from irregular breathing cycles, which cause artifacts, are not acquired by gating CT acquisition by the respiratory signal. A proof-of-principle application of the respiratory regularity gated 4D CT method using patient respiratory signals demonstrates the potential of this method to reduce artifacts currently found in 4D CT scans. Numerical simulations indicate a potential reduction in motion within a respiratory phase bin by 20-40% depending on tolerances chosen. Additional advantages of the proposed method are dose reduction by eliminating unnecessary oversampling and obviating the need for post-processing to create the 4D CT data set. PMID:18044305

  3. Acquiring 4D Thoracic CT Scans Using Ciné CT Acquisition

    NASA Astrophysics Data System (ADS)

    Low, Daniel

    One method for acquiring 4D thoracic CT scans is to use ciné acquisition. Ciné acquisition is conducted by rotating the gantry and acquiring x-ray projections while keeping the couch stationary. After a complete rotation, a single set of CT slices, the number corresponding to the number of CT detector rows, is produced. The rotation period is typically sub second so each image set corresponds to a single point in time. The ciné image acquisition is repeated for at least one breathing cycle to acquire images throughout the breathing cycle. Once the images are acquired at a single couch position, the couch is moved to the abutting position and the acquisition is repeated. Post-processing of the images sets typically resorts the sets into breathing phases, stacking images from a specific phase to produce a thoracic CT scan at that phase. Benefits of the ciné acquisition protocol include, the ability to precisely identify the phase with respect to the acquired image, the ability to resort images after reconstruction, and the ability to acquire images over arbitrarily long times and for arbitrarily many images (within dose constraints).

  4. TH-E-17A-07: Improved Cine Four-Dimensional Computed Tomography (4D CT) Acquisition and Processing Method

    SciTech Connect

    Castillo, S; Castillo, R; Castillo, E; Pan, T; Ibbott, G; Balter, P; Hobbs, B; Dai, J; Guerrero, T

    2014-06-15

    Purpose: Artifacts arising from the 4D CT acquisition and post-processing methods add systematic uncertainty to the treatment planning process. We propose an alternate cine 4D CT acquisition and post-processing method to consistently reduce artifacts, and explore patient parameters indicative of image quality. Methods: In an IRB-approved protocol, 18 patients with primary thoracic malignancies received a standard cine 4D CT acquisition followed by an oversampling 4D CT that doubled the number of images acquired. A second cohort of 10 patients received the clinical 4D CT plus 3 oversampling scans for intra-fraction reproducibility. The clinical acquisitions were processed by the standard phase sorting method. The oversampling acquisitions were processed using Dijkstras algorithm to optimize an artifact metric over available image data. Image quality was evaluated with a one-way mixed ANOVA model using a correlation-based artifact metric calculated from the final 4D CT image sets. Spearman correlations and a linear mixed model tested the association between breathing parameters, patient characteristics, and image quality. Results: The oversampling 4D CT scans reduced artifact presence significantly by 27% and 28%, for the first cohort and second cohort respectively. From cohort 2, the inter-replicate deviation for the oversampling method was within approximately 13% of the cross scan average at the 0.05 significance level. Artifact presence for both clinical and oversampling methods was significantly correlated with breathing period (ρ=0.407, p-value<0.032 clinical, ρ=0.296, p-value<0.041 oversampling). Artifact presence in the oversampling method was significantly correlated with amount of data acquired, (ρ=-0.335, p-value<0.02) indicating decreased artifact presence with increased breathing cycles per scan location. Conclusion: The 4D CT oversampling acquisition with optimized sorting reduced artifact presence significantly and reproducibly compared to the phase

  5. Technical evaluation of different respiratory monitoring systems used for 4D CT acquisition under free breathing.

    PubMed

    Heinz, Christian; Reiner, Michael; Belka, Claus; Walter, Franziska; Söhn, Matthias

    2015-01-01

    Respiratory monitoring systems are required to supply CT scanners with information on the patient's breathing during the acquisition of a respiration-correlated computer tomography (RCCT), also referred to as 4D CT. The information a respiratory monitoring system has to provide to the CT scanner depends on the specific scanner. The purpose of this study is to compare two different respiratory monitoring systems (Anzai Respiratory Gating System; C-RAD Sentinel) with respect to their applicability in combination with an Aquilion Large Bore CT scanner from Toshiba. The scanner used in our clinic does not make use of the full time dependent breathing signal, but only single trigger pulses indicating the beginning of a new breathing cycle. Hence the attached respiratory monitoring system is expected to deliver accurate online trigger pulse for each breathing cycle. The accuracy of the trigger pulses sent to the CT scanner has to be ensured by the selected respiratory monitoring system. Since a trigger pulse (output signal) of a respiratory monitoring system is a function of the measured breathing signal (input signal), the typical clinical range of the input signal is estimated for both examined respiratory monitoring systems. Both systems are analyzed based on the following parameters: time resolution, signal amplitude, noise, signal-to-noise ratio (SNR), signal linearity, trigger compatibility, and clinical examples. The Anzai system shows a better SNR (≥ 28 dB) than the Sentinel system (≥ 14.6 dB). In terms of compatibility with the cycle-based image sorting algorithm of the Toshiba CT scanner, the Anzai system benefits from the possibility to generate cycle-based triggers, whereas the Sentinel system is only able to generate amplitude-based triggers. In clinical practice, the combination of a Toshiba CT scanner and the Anzai system will provide better results due to the compatibility of the image sorting and trigger release methods. PMID:26103168

  6. Quantifying the impact of respiratory-gated 4D CT acquisition on thoracic image quality: A digital phantom study

    SciTech Connect

    Bernatowicz, K. Knopf, A.; Lomax, A.; Keall, P.; Kipritidis, J.; Mishra, P.

    2015-01-15

    Purpose: Prospective respiratory-gated 4D CT has been shown to reduce tumor image artifacts by up to 50% compared to conventional 4D CT. However, to date no studies have quantified the impact of gated 4D CT on normal lung tissue imaging, which is important in performing dose calculations based on accurate estimates of lung volume and structure. To determine the impact of gated 4D CT on thoracic image quality, the authors developed a novel simulation framework incorporating a realistic deformable digital phantom driven by patient tumor motion patterns. Based on this framework, the authors test the hypothesis that respiratory-gated 4D CT can significantly reduce lung imaging artifacts. Methods: Our simulation framework synchronizes the 4D extended cardiac torso (XCAT) phantom with tumor motion data in a quasi real-time fashion, allowing simulation of three 4D CT acquisition modes featuring different levels of respiratory feedback: (i) “conventional” 4D CT that uses a constant imaging and couch-shift frequency, (ii) “beam paused” 4D CT that interrupts imaging to avoid oversampling at a given couch position and respiratory phase, and (iii) “respiratory-gated” 4D CT that triggers acquisition only when the respiratory motion fulfills phase-specific displacement gating windows based on prescan breathing data. Our framework generates a set of ground truth comparators, representing the average XCAT anatomy during beam-on for each of ten respiratory phase bins. Based on this framework, the authors simulated conventional, beam-paused, and respiratory-gated 4D CT images using tumor motion patterns from seven lung cancer patients across 13 treatment fractions, with a simulated 5.5 cm{sup 3} spherical lesion. Normal lung tissue image quality was quantified by comparing simulated and ground truth images in terms of overall mean square error (MSE) intensity difference, threshold-based lung volume error, and fractional false positive/false negative rates. Results

  7. Comparison of an alternative and existing binning methods to reduce the acquisition duration of 4D PET/CT

    SciTech Connect

    Didierlaurent, David Ribes, Sophie; Caselles, Olivier; Jaudet, Cyril; Dierickx, Lawrence O.; Zerdoud, Slimane; Brillouet, Severine; Weits, Kathleen; Batatia, Hadj; Courbon, Frédéric

    2014-11-01

    Purpose: Respiratory motion is a source of artifacts that reduce image quality in PET. Four dimensional (4D) PET/CT is one approach to overcome this problem. Existing techniques to limiting the effects of respiratory motions are based on prospective phase binning which requires a long acquisition duration (15–25 min). This time is uncomfortable for the patients and limits the clinical exploitation of 4D PET/CT. In this work, the authors evaluated an existing method and an alternative retrospective binning method to reduce the acquisition duration of 4D PET/CT. Methods: The authors studied an existing mixed-amplitude binning (MAB) method and an alternative binning method by mixed-phases (MPhB). Before implementing MPhB, they analyzed the regularity of the breathing patterns in patients. They studied the breathing signal drift and missing CT slices that could be challenging for implementing MAB. They compared the performance of MAB and MPhB with current binning methods to measure the maximum uptake, internal volume, and maximal range of tumor motion. Results: MPhB can be implemented depending on an optimal phase (in average, the exhalation peak phase −4.1% of the entire breathing cycle duration). Signal drift of patients was in average 35% relative to the breathing amplitude. Even after correcting this drift, MAB was feasible in 4D CT for only 64% of patients. No significant differences appeared between the different binning methods to measure the maximum uptake, internal volume, and maximal range of tumor motion. The authors also determined the inaccuracies of MAB and MPhB to measure the maximum amplitude of tumor motion with three bins (less than 3 mm for movement inferior to 12 mm, up to 6.4 mm for a 21 mm movement). Conclusions: The authors proposed an alternative binning method by mixed-phase binning that halves the acquisition duration of 4D PET/CT. Mixed-amplitude binning was challenging because of signal drift and missing CT slices. They showed that more

  8. Helical 4D CT and Comparison with Cine 4D CT

    NASA Astrophysics Data System (ADS)

    Pan, Tinsu

    4D CT was one of the most important developments in radiation oncology in the last decade. Its early development in single slice CT and commercialization in multi-slice CT has radically changed our practice in radiation treatment of lung cancer, and has enabled the stereotactic radiosurgery of early stage lung cancer. In this chapter, we will document the history of 4D CT development, detail the data sufficiency condition governing the 4D CT data collection; present the design of the commercial helical 4D CTs from Philips and Siemens; compare the differences between the helical 4D CT and the GE cine 4D CT in data acquisition, slice thickness, acquisition time and work flow; review the respiratory monitoring devices; and understand the causes of image artifacts in 4D CT.

  9. Semiautomatic method to identify the best phase for gated RT in lung region by 4D-PET/CT acquisitions

    SciTech Connect

    Mancosu, Pietro; Danna, Massimo; Bettinardi, Valentino; Aquilina, Mark Anthony; Lobefalo, Francesca; Cozzi, Luca; Fogliata, Antonella; Scorsetti, Marta

    2011-01-15

    Purpose: Delineating tumor motion by four-dimensional positron emission tomography/computed tomography (4D-PET/CT) is a crucial step for gated radiotherapy (RT). This article quantitatively evaluates semiautomatic algorithms for tumor shift estimation in the lung region due to patient respiration by 4D-PET/CT, in order to support the selection of the best phases for gated RT, by considering the most stable phases of the breathing cycle. Methods: Three mobile spheres and ten selected lesions were included in this study. 4D-PET/CT data were reconstructed and classified into six/ten phases. The semiautomatic algorithms required the generation of single sets of images representative of the full target motion, used as masks for segmenting the phases. For 4D-CT, a pre-established HU range was used, whereas three thresholds (100%, 80%, and 40%) were evaluated for 4D-PET. By using these segmentations, the authors estimated the lesion motion from the shifting centroids, and the phases with the least motion were also deduced including the phases with a curve slope less than 2 mm/{Delta}phase. The proposed algorithms were validated by comparing the results to those generated entirely by manual contouring. Results: In the phantom study, the mean difference between the manual contour and the semiautomatic technique was 0.1{+-}0.1 mm for 4D-CT and 0.2{+-}0.1 mm for the 4D-PET based on 40% threshold. In the patients' series, the mean difference was 0.9{+-}0.6 mm for 4D-CT and 0.8{+-}0.2 mm for the 4D-PET based on 40% threshold. Conclusions: Estimation of lesion motion by the proposed semiautomatic algorithm can be used to evaluate tumor motion due to breathing.

  10. 4D micro-CT using fast prospective gating

    NASA Astrophysics Data System (ADS)

    Guo, Xiaolian; Johnston, Samuel M.; Qi, Yi; Johnson, G. Allan; Badea, Cristian T.

    2012-01-01

    Micro-CT is currently used in preclinical studies to provide anatomical information. But, there is also significant interest in using this technology to obtain functional information. We report here a new sampling strategy for 4D micro-CT for functional cardiac and pulmonary imaging. Rapid scanning of free-breathing mice is achieved with fast prospective gating (FPG) implemented on a field programmable gate array. The method entails on-the-fly computation of delays from the R peaks of the ECG signals or the peaks of the respiratory signals for the triggering pulses. Projection images are acquired for all cardiac or respiratory phases at each angle before rotating to the next angle. FPG can deliver the faster scan time of retrospective gating (RG) with the regular angular distribution of conventional prospective gating for cardiac or respiratory gating. Simultaneous cardio-respiratory gating is also possible with FPG in a hybrid retrospective/prospective approach. We have performed phantom experiments to validate the new sampling protocol and compared the results from FPG and RG in cardiac imaging of a mouse. Additionally, we have evaluated the utility of incorporating respiratory information in 4D cardiac micro-CT studies with FPG. A dual-source micro-CT system was used for image acquisition with pulsed x-ray exposures (80 kVp, 100 mA, 10 ms). The cardiac micro-CT protocol involves the use of a liposomal blood pool contrast agent containing 123 mg I ml-1 delivered via a tail vein catheter in a dose of 0.01 ml g-1 body weight. The phantom experiment demonstrates that FPG can distinguish the successive phases of phantom motion with minimal motion blur, and the animal study demonstrates that respiratory FPG can distinguish inspiration and expiration. 4D cardiac micro-CT imaging with FPG provides image quality superior to RG at an isotropic voxel size of 88 µm and 10 ms temporal resolution. The acquisition time for either sampling approach is less than 5 min. The

  11. A Novel Fast Helical 4D-CT Acquisition Technique to Generate Low-Noise Sorting Artifact–Free Images at User-Selected Breathing Phases

    SciTech Connect

    Thomas, David; Lamb, James; White, Benjamin; Jani, Shyam; Gaudio, Sergio; Lee, Percy; Ruan, Dan; McNitt-Gray, Michael; Low, Daniel

    2014-05-01

    Purpose: To develop a novel 4-dimensional computed tomography (4D-CT) technique that exploits standard fast helical acquisition, a simultaneous breathing surrogate measurement, deformable image registration, and a breathing motion model to remove sorting artifacts. Methods and Materials: Ten patients were imaged under free-breathing conditions 25 successive times in alternating directions with a 64-slice CT scanner using a low-dose fast helical protocol. An abdominal bellows was used as a breathing surrogate. Deformable registration was used to register the first image (defined as the reference image) to the subsequent 24 segmented images. Voxel-specific motion model parameters were determined using a breathing motion model. The tissue locations predicted by the motion model in the 25 images were compared against the deformably registered tissue locations, allowing a model prediction error to be evaluated. A low-noise image was created by averaging the 25 images deformed to the first image geometry, reducing statistical image noise by a factor of 5. The motion model was used to deform the low-noise reference image to any user-selected breathing phase. A voxel-specific correction was applied to correct the Hounsfield units for lung parenchyma density as a function of lung air filling. Results: Images produced using the model at user-selected breathing phases did not suffer from sorting artifacts common to conventional 4D-CT protocols. The mean prediction error across all patients between the breathing motion model predictions and the measured lung tissue positions was determined to be 1.19 ± 0.37 mm. Conclusions: The proposed technique can be used as a clinical 4D-CT technique. It is robust in the presence of irregular breathing and allows the entire imaging dose to contribute to the resulting image quality, providing sorting artifact–free images at a patient dose similar to or less than current 4D-CT techniques.

  12. Fast X-ray micro-CT for real-time 4D observation

    NASA Astrophysics Data System (ADS)

    Takano, H.; Yoshida, K.; Tsuji, T.; Koyama, T.; Tsusaka, Y.; Kagoshima, Y.

    2009-09-01

    Fast X-ray computed tomography (CT) system with sub-second order measurement for single CT acquisition has been developed. The system, consisting of a high-speed sample rotation stage and a high-speed X-ray camera, is constructed at synchrotron radiation beamline in order to utilize fully intense X-rays. A time-resolving CT movie (i.e. 4D CT) can be available by operating the fast CT system continuously. Real-time observation of water absorbing process of super-absorbent polymer (SAP) has been successfully performed with the 4D CT operation.

  13. Mapping motion from 4D-MRI to 3D-CT for use in 4D dose calculations: A technical feasibility study

    SciTech Connect

    Boye, Dirk; Lomax, Tony; Knopf, Antje

    2013-06-15

    Purpose: Target sites affected by organ motion require a time resolved (4D) dose calculation. Typical 4D dose calculations use 4D-CT as a basis. Unfortunately, 4D-CT images have the disadvantage of being a 'snap-shot' of the motion during acquisition and of assuming regularity of breathing. In addition, 4D-CT acquisitions involve a substantial additional dose burden to the patient making many, repeated 4D-CT acquisitions undesirable. Here the authors test the feasibility of an alternative approach to generate patient specific 4D-CT data sets. Methods: In this approach motion information is extracted from 4D-MRI. Simulated 4D-CT data sets [which the authors call 4D-CT(MRI)] are created by warping extracted deformation fields to a static 3D-CT data set. The employment of 4D-MRI sequences for this has the advantage that no assumptions on breathing regularity are made, irregularities in breathing can be studied and, if necessary, many repeat imaging studies (and consequently simulated 4D-CT data sets) can be performed on patients and/or volunteers. The accuracy of 4D-CT(MRI)s has been validated by 4D proton dose calculations. Our 4D dose algorithm takes into account displacements as well as deformations on the originating 4D-CT/4D-CT(MRI) by calculating the dose of each pencil beam based on an individual time stamp of when that pencil beam is applied. According to corresponding displacement and density-variation-maps the position and the water equivalent range of the dose grid points is adjusted at each time instance. Results: 4D dose distributions, using 4D-CT(MRI) data sets as input were compared to results based on a reference conventional 4D-CT data set capturing similar motion characteristics. Almost identical 4D dose distributions could be achieved, even though scanned proton beams are very sensitive to small differences in the patient geometry. In addition, 4D dose calculations have been performed on the same patient, but using 4D-CT(MRI) data sets based on

  14. Abdominal and pancreatic motion correlation using 4D CT, 4D transponders, and a gating belt.

    PubMed

    Betancourt, Ricardo; Zou, Wei; Plastaras, John P; Metz, James M; Teo, Boon-Keng; Kassaee, Alireza

    2013-01-01

    The correlation between the pancreatic and external abdominal motion due to respiration was investigated on two patients. These studies utilized four dimensional computer tomography (4D CT), a four dimensional (4D) electromagnetic transponder system, and a gating belt system. One 4D CT study was performed during simulation to quantify the pancreatic motion using computer tomography images at eight breathing phases. The motion under free breathing and breath-hold were analyzed for the 4D electromagnetic transponder system and the gating belt system during treatment. A linear curve was fitted for all data sets and correlation factors were evaluated between the 4D electromagnetic transponder system and the gating belt system data. The 4D CT study demonstrated a modest correlation between the external marker and the pancreatic motion with R-square values larger than 0.8 for the inferior-superior (inf-sup). Then, the relative pressure from the belt gating system correlated well with the 4D electromagnetic transponder system's motion in the anterior-posterior (ant-post) and the inf-post directions. These directions have a correlation value of -0.93 and 0.76, while the lateral only had a 0.03 correlation coefficient. Based on our limited study, external surrogates can be used as predictors of the pancreatic motion in the inf-sup and the ant-post directions. Although there is a low correlation on the lateral direction, its motion is significantly shorter. In conclusion, an appropriate treatment delivery can be used for pancreatic cancer when an internal tracking system, such as the 4D electromagnetic transponder system, is unavailable. PMID:23652242

  15. Abdominal organ motion measured using 4D CT

    SciTech Connect

    Brandner, Edward D.; Wu, Andrew . E-mail: andrew.wu@jefferson.edu; Chen, Hungcheng; Heron, Dwight; Kalnicki, Shalom; Komanduri, Krishna; Gerszten, Kristina; Burton, Steve; Ahmed, Irfan; Shou, Zhenyu

    2006-06-01

    Purpose: To measure respiration-induced abdominal organ motion using four-dimensional computed tomography (4D CT) scanning and to examine the organ paths. Methods and Materials: During 4D CT scanning, consecutive CT images are acquired of the patient at each couch position. Simultaneously, the patient's respiratory pattern is recorded using an external marker block taped to the patient's abdomen. This pattern is used to retrospectively organize the CT images into multiple three-dimensional images, each representing one breathing phase. These images are analyzed to measure organ motion between each phase. The displacement from end expiration is compared to a displacement limit that represents acceptable dosimetric results (5 mm). Results: The organs measured in 13 patients were the liver, spleen, and left and right kidneys. Their average superior to inferior absolute displacements were 1.3 cm for the liver, 1.3 cm for the spleen, 1.1 cm for the left kidney, and 1.3 cm for the right kidney. Although the organ paths varied among patients, 5 mm of superior to inferior displacement from end expiration resulted in less than 5 mm of displacement in the other directions for 41 of 43 organs measured. Conclusions: Four-dimensional CT scanning can accurately measure abdominal organ motion throughout respiration. This information may result in greater organ sparing and planning target volume coverage.

  16. Brain tissue segmentation in 4D CT using voxel classification

    NASA Astrophysics Data System (ADS)

    van den Boom, R.; Oei, M. T. H.; Lafebre, S.; Oostveen, L. J.; Meijer, F. J. A.; Steens, S. C. A.; Prokop, M.; van Ginneken, B.; Manniesing, R.

    2012-02-01

    A method is proposed to segment anatomical regions of the brain from 4D computer tomography (CT) patient data. The method consists of a three step voxel classification scheme, each step focusing on structures that are increasingly difficult to segment. The first step classifies air and bone, the second step classifies vessels and the third step classifies white matter, gray matter and cerebrospinal fluid. As features the time averaged intensity value and the temporal intensity change value were used. In each step, a k-Nearest-Neighbor classifier was used to classify the voxels. Training data was obtained by placing regions of interest in reconstructed 3D image data. The method has been applied to ten 4D CT cerebral patient data. A leave-one-out experiment showed consistent and accurate segmentation results.

  17. Phase and amplitude binning for 4D-CT imaging.

    PubMed

    Abdelnour, A F; Nehmeh, S A; Pan, T; Humm, J L; Vernon, P; Schöder, H; Rosenzweig, K E; Mageras, G S; Yorke, E; Larson, S M; Erdi, Y E

    2007-06-21

    We compare the consistency and accuracy of two image binning approaches used in 4D-CT imaging. One approach, phase binning (PB), assigns each breathing cycle 2pi rad, within which the images are grouped. In amplitude binning (AB), the images are assigned bins according to the breathing signal's full amplitude. To quantitate both approaches we used a NEMA NU2-2001 IEC phantom oscillating in the axial direction and at random frequencies and amplitudes, approximately simulating a patient's breathing. 4D-CT images were obtained using a four-slice GE Lightspeed CT scanner operating in cine mode. We define consistency error as a measure of ability to correctly bin over repeated cycles in the same field of view. Average consistency error mue+/-sigmae in PB ranged from 18%+/-20% to 30%+/-35%, while in AB the error ranged from 11%+/-14% to 20%+/-24%. In PB nearly all bins contained sphere slices. AB was more accurate, revealing empty bins where no sphere slices existed. As a proof of principle, we present examples of two non-small cell lung carcinoma patients' 4D-CT lung images binned by both approaches. While AB can lead to gaps in the coronal images, depending on the patient's breathing pattern, PB exhibits no gaps but suffers visible artifacts due to misbinning, yielding images that cover a relatively large amplitude range. AB was more consistent, though often resulted in gaps when no data existed due to patients' breathing pattern. We conclude AB is more accurate than PB. This has important consequences to treatment planning and diagnosis. PMID:17664557

  18. SU-E-J-148: Tools for Development of 4D Proton CT

    SciTech Connect

    Dou, T; Ramos-Mendez, J; Piersimoni, P; Giacometti, V; Penfold, S; Censor, Y; Faddegon, B; Low, D; Schulte, R

    2015-06-15

    Purpose: To develop tools for performing 4D proton computed tomography (CT). Methods: A suitable patient with a tumor in the right lower lobe was selected from a set of 4D CT scans. The volumetric CT images formed the basis for calculating the parameters of a breathing model that allows reconstruction of a static reference CT and CT images in each breathing phase. The images were imported into the TOPAS Monte Carlo simulation platform for simulating an experimental proton CT scan with 45 projections spaced by 4 degree intervals. Each projection acquired data for 2 seconds followed by a gantry rotation for 2 seconds without acquisition. The scan covered 180 degrees with individual protons passing through a 9-cm slab of the patient’s lung covering the moving tumor. An initial proton energy sufficient for penetrating the patient from all directions was determined. Performing the proton CT simulation, TOPAS provided output of the proton energy and coordinates registered in two planes before and after the patient, respectively. The set of projection data was then used with an iterative reconstruction algorithm to generate a volumetric proton CT image set of the static reference image and the image obtained under breathing motion, respectively. Results: An initial proton energy of 230 MeV was found to be sufficient, while for an initial energy of 200 MeV a substantial number of protons did not penetrate the patient. The reconstruction of the static reference image set provided sufficient detail for treatment planning. Conclusion: We have developed tools to perform studies of proton CT in the presence of lung motion based on the TOPAS simulation toolkit. This will allow to optimize 4D reconstruction algorithms by synchronizing the acquired proton CT data with a breathing signal and utilizing a breathing model obtained prior to the proton CT scan. This research has been supported by the National Institute Of Biomedical Imaging And Bioengineering of the National

  19. Complete valvular heart apparatus model from 4D cardiac CT.

    PubMed

    Grbic, Sasa; Ionasec, Razvan; Vitanovski, Dime; Voigt, Ingmar; Wang, Yang; Georgescu, Bogdan; Navab, Nassir; Comaniciu, Dorin

    2012-07-01

    The cardiac valvular apparatus, composed of the aortic, mitral, pulmonary and tricuspid valves, is an essential part of the anatomical, functional and hemodynamic characteristics of the heart and the cardiovascular system as a whole. Valvular heart diseases often involve multiple dysfunctions and require joint assessment and therapy of the valves. In this paper, we propose a complete and modular patient-specific model of the cardiac valvular apparatus estimated from 4D cardiac CT data. A new constrained Multi-linear Shape Model (cMSM), conditioned by anatomical measurements, is introduced to represent the complex spatio-temporal variation of the heart valves. The cMSM is exploited within a learning-based framework to efficiently estimate the patient-specific valve parameters from cine images. Experiments on 64 4D cardiac CT studies demonstrate the performance and clinical potential of the proposed method. Our method enables automatic quantitative evaluation of the complete valvular apparatus based on non-invasive imaging techniques. In conjunction with existent patient-specific chamber models, the presented valvular model enables personalized computation modeling and realistic simulation of the entire cardiac system. PMID:22481023

  20. An optical flow based method for improved reconstruction of 4D CT data sets acquired during free breathing

    SciTech Connect

    Ehrhardt, Jan; Werner, Rene; Saering, Dennis; Frenzel, Thorsten; Lu Wei; Low, Daniel; Handels, Heinz

    2007-02-15

    Respiratory motion degrades anatomic position reproducibility and leads to issues affecting image acquisition, treatment planning, and radiation delivery. Four-dimensional (4D) computer tomography (CT) image acquisition can be used to measure the impact of organ motion and to explicitly account for respiratory motion during treatment planning and radiation delivery. Modern CT scanners can only scan a limited region of the body simultaneously and patients have to be scanned in segments consisting of multiple slices. A respiratory signal (spirometer signal or surface tracking) is used to reconstruct a 4D data set by sorting the CT scans according to the couch position and signal coherence with predefined respiratory phases. But artifacts can occur if there are no acquired data segments for exactly the same respiratory state for all couch positions. These artifacts are caused by device-dependent limitations of gantry rotation, image reconstruction times and by the variability of the patient's respiratory pattern. In this paper an optical flow based method for improved reconstruction of 4D CT data sets from multislice CT scans is presented. The optical flow between scans at neighboring respiratory states is estimated by a non-linear registration method. The calculated velocity field is then used to reconstruct a 4D CT data set by interpolating data at exactly the predefined respiratory phase. Our reconstruction method is compared with the usually used reconstruction based on amplitude sorting. The procedures described were applied to reconstruct 4D CT data sets for four cancer patients and a qualitative and quantitative evaluation of the optical flow based reconstruction method was performed. Evaluation results show a relevant reduction of reconstruction artifacts by our technique. The reconstructed 4D data sets were used to quantify organ displacements and to visualize the abdominothoracic organ motion.

  1. Graph-based retrospective 4D image construction from free-breathing MRI slice acquisitions

    NASA Astrophysics Data System (ADS)

    Tong, Yubing; Udupa, Jayaram K.; Ciesielski, Krzysztof C.; McDonough, Joseph M.; Mong, Andrew; Campbell, Robert M.

    2014-03-01

    4D or dynamic imaging of the thorax has many potential applications [1, 2]. CT and MRI offer sufficient speed to acquire motion information via 4D imaging. However they have different constraints and requirements. For both modalities both prospective and retrospective respiratory gating and tracking techniques have been developed [3, 4]. For pediatric imaging, x-ray radiation becomes a primary concern and MRI remains as the de facto choice. The pediatric subjects we deal with often suffer from extreme malformations of their chest wall, diaphragm, and/or spine, as such patient cooperation needed by some of the gating and tracking techniques are difficult to realize without causing patient discomfort. Moreover, we are interested in the mechanical function of their thorax in its natural form in tidal breathing. Therefore free-breathing MRI acquisition is the ideal modality of imaging for these patients. In our set up, for each coronal (or sagittal) slice position, slice images are acquired at a rate of about 200-300 ms/slice over several natural breathing cycles. This produces typically several thousands of slices which contain both the anatomic and dynamic information. However, it is not trivial to form a consistent and well defined 4D volume from these data. In this paper, we present a novel graph-based combinatorial optimization solution for constructing the best possible 4D scene from such data entirely in the digital domain. Our proposed method is purely image-based and does not need breath holding or any external surrogates or instruments to record respiratory motion or tidal volume. Both adult and children patients' data are used to illustrate the performance of the proposed method. Experimental results show that the reconstructed 4D scenes are smooth and consistent spatially and temporally, agreeing with known shape and motion of the lungs.

  2. 4D micro-CT for cardiac and perfusion applications with view under sampling

    NASA Astrophysics Data System (ADS)

    Badea, Cristian T.; Johnston, Samuel M.; Qi, Yi; Johnson, G. Allan

    2011-06-01

    Micro-CT is commonly used in preclinical studies to provide anatomical information. There is growing interest in obtaining functional measurements from 4D micro-CT. We report here strategies for 4D micro-CT with a focus on two applications: (i) cardiac imaging based on retrospective gating and (ii) pulmonary perfusion using multiple contrast injections/rotations paradigm. A dual source micro-CT system is used for image acquisition with a sampling rate of 20 projections per second. The cardiac micro-CT protocol involves the use of a liposomal blood pool contrast agent. Fast scanning of free breathing mice is achieved using retrospective gating. The ECG and respiratory signals are used to sort projections into ten cardiac phases. The pulmonary perfusion protocol uses a conventional contrast agent (Isovue 370) delivered by a micro-injector in four injections separated by 2 min intervals to allow for clearance. Each injection is synchronized with the rotation of the animal, and each of the four rotations is started with an angular offset of 22.5 from the starting angle of the previous rotation. Both cardiac and perfusion protocols result in an irregular angular distribution of projections that causes significant streaking artifacts in reconstructions when using traditional filtered backprojection (FBP) algorithms. The reconstruction involves the use of the point spread function of the micro-CT system for each time point, and the analysis of the distribution of the reconstructed data in the Fourier domain. This enables us to correct for angular inconsistencies via deconvolution and identify regions where data is missing. The missing regions are filled with data from a high quality but temporally averaged prior image reconstructed with all available projections. Simulations indicate that deconvolution successfully removes the streaking artifacts while preserving temporal information. 4D cardiac micro-CT in a mouse was performed with adequate image quality at isotropic

  3. Effect of heart rate on CT angiography using the enhanced cardiac model of the 4D NCAT

    NASA Astrophysics Data System (ADS)

    Segars, W. P.; Taguchi, K.; Fung, G. S. K.; Fishman, E. K.; Tsui, B. M. W.

    2006-03-01

    We investigate the effect of heart rate on the quality and artifact generation in coronary artery images obtained using multi-slice computed tomography (MSCT) with the purpose of finding the optimal time resolution for data acquisition. To perform the study, we used the 4D NCAT phantom, a computer model of the normal human anatomy and cardiac and respiratory motions developed in our laboratory. Although capable of being far more realistic, the 4D NCAT cardiac model was originally designed for low-resolution imaging research, and lacked the anatomical detail to be applicable to high-resolution CT. In this work, we updated the cardiac model to include a more detailed anatomy and physiology based on high-resolution clinical gated MSCT data. To demonstrate its utility in high-resolution dynamic CT imaging research, the enhanced 4D NCAT was then used in a pilot simulation study to investigate the effect of heart rate on CT angiography. The 4D NCAT was used to simulate patients with different heart rates (60-120 beats/minute) and with various cardiac plaques of known size and location within the coronary arteries. For each simulated patient, MSCT projection data was generated with data acquisition windows ranging from 100 to 250 ms centered within the quiet phase (mid-diastole) of the heart using an analytical CT projection algorithm. CT images were reconstructed from the projection data, and the contrast of the plaques was then measured to assess the effect of heart rate and to determine the optimal time resolution required for each case. The 4D NCAT phantom with its realistic model for the cardiac motion was found to provide a valuable tool from which to optimize CT cardiac applications. Our results indicate the importance of optimizing the time resolution with regard to heart rate and plaque location for improved CT images at a reduced patient dose.

  4. Lung Segmentation in 4D CT Volumes Based on Robust Active Shape Model Matching

    PubMed Central

    Gill, Gurman; Beichel, Reinhard R.

    2015-01-01

    Dynamic and longitudinal lung CT imaging produce 4D lung image data sets, enabling applications like radiation treatment planning or assessment of response to treatment of lung diseases. In this paper, we present a 4D lung segmentation method that mutually utilizes all individual CT volumes to derive segmentations for each CT data set. Our approach is based on a 3D robust active shape model and extends it to fully utilize 4D lung image data sets. This yields an initial segmentation for the 4D volume, which is then refined by using a 4D optimal surface finding algorithm. The approach was evaluated on a diverse set of 152 CT scans of normal and diseased lungs, consisting of total lung capacity and functional residual capacity scan pairs. In addition, a comparison to a 3D segmentation method and a registration based 4D lung segmentation approach was performed. The proposed 4D method obtained an average Dice coefficient of 0.9773 ± 0.0254, which was statistically significantly better (p value ≪0.001) than the 3D method (0.9659 ± 0.0517). Compared to the registration based 4D method, our method obtained better or similar performance, but was 58.6% faster. Also, the method can be easily expanded to process 4D CT data sets consisting of several volumes. PMID:26557844

  5. Correlation between internal fiducial tumor motion and external marker motion for liver tumors imaged with 4D-CT

    SciTech Connect

    Beddar, A. Sam . E-mail: abeddar@mdanderson.org; Kainz, Kristofer; Briere, Tina Marie; Tsunashima, Yoshikazu; Pan Tinsu; Prado, Karl; Mohan, Radhe; Gillin, Michael; Krishnan, Sunil

    2007-02-01

    Purpose: We investigated the correlation between the motions of an external marker and internal fiducials implanted in the liver for 8 patients undergoing respiratory-based computed tomography (four-dimensional CT [4D-CT]) procedures. Methods and Materials: The internal fiducials were gold seeds, 3 mm in length and 1.2 mm in diameter. Four patients each had one implanted fiducial, and the other four had three implanted fiducials. The external marker was a plastic box, which is part of the Real-Time Position Management System (RPM) used to track the patient's respiration. Each patient received a standard helical CT scan followed by a time-correlated CT-image acquisition (4D-CT). The 4D-CT images were reconstructed in 10 separate phases covering the entire respiratory cycle. Results: The internal fiducial motion is predominant in the superior-inferior direction, with a range of 7.5-17.5 mm. The correlation between external respiration and internal fiducial motion is best during expiration. For 2 patients with their three fiducials separated by a maximum of 3.2 cm, the motions of the fiducials were well correlated, whereas for 2 patients with more widely spaced fiducials, there was less correlation. Conclusions: In general, there is a good correlation between internal fiducial motion imaged by 4D-CT and external marker motion. We have demonstrated that gating may be best performed at the end of the respiratory cycle. Special attention should be paid to gating for patients whose fiducials do not move in synchrony, because targeting on the correct respiratory amplitude alone would not guarantee that the entire tumor volume is within the treatment field.

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

    SciTech Connect

    Xue, M; Patel, K; Regine, W; Lane, B; D'Souza, W; Lu, W; Klahr, P

    2014-06-01

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

  7. Resolution enhancement of lung 4D-CT data using multiscale interphase iterative nonlocal means

    SciTech Connect

    Zhang Yu; Yap, Pew-Thian; Wu Guorong; Feng Qianjin; Chen Wufan; Lian Jun; Shen Dinggang

    2013-05-15

    Purpose: Four-dimensional computer tomography (4D-CT) has been widely used in lung cancer radiotherapy due to its capability in providing important tumor motion information. However, the prolonged scanning duration required by 4D-CT causes considerable increase in radiation dose. To minimize the radiation-related health risk, radiation dose is often reduced at the expense of interslice spatial resolution. However, inadequate resolution in 4D-CT causes artifacts and increases uncertainty in tumor localization, which eventually results in extra damages of healthy tissues during radiotherapy. In this paper, the authors propose a novel postprocessing algorithm to enhance the resolution of lung 4D-CT data. Methods: The authors' premise is that anatomical information missing in one phase can be recovered from the complementary information embedded in other phases. The authors employ a patch-based mechanism to propagate information across phases for the reconstruction of intermediate slices in the longitudinal direction, where resolution is normally the lowest. Specifically, the structurally matching and spatially nearby patches are combined for reconstruction of each patch. For greater sensitivity to anatomical details, the authors employ a quad-tree technique to adaptively partition the image for more fine-grained refinement. The authors further devise an iterative strategy for significant enhancement of anatomical details. Results: The authors evaluated their algorithm using a publicly available lung data that consist of 10 4D-CT cases. The authors' algorithm gives very promising results with significantly enhanced image structures and much less artifacts. Quantitative analysis shows that the authors' algorithm increases peak signal-to-noise ratio by 3-4 dB and the structural similarity index by 3%-5% when compared with the standard interpolation-based algorithms. Conclusions: The authors have developed a new algorithm to improve the resolution of 4D-CT. It outperforms

  8. Tumor and normal tissue motion in the thorax during respiration: Analysis of volumetric and positional variations using 4D CT

    SciTech Connect

    Weiss, Elisabeth . E-mail: eweiss@mcvh-vcu.edu; Wijesooriya, Krishni; Dill, S. Vaughn; Keall, Paul J.

    2007-01-01

    Purpose: To investigate temporospatial variations of tumor and normal tissue during respiration in lung cancer patients. Methods and Materials: In 14 patients, gross tumor volume (GTV) and normal tissue structures were manually contoured on four-dimensional computed tomography (4D-CT) scans. Structures were evaluated for volume changes, centroid (center of mass) motion, and phase dependence of variations relative to inspiration. Only volumetrically complete structures were used for analysis (lung in 2, heart in 8, all other structures in >10 patients). Results: During respiration, the magnitude of contoured volumes varied up to 62.5% for GTVs, 25.5% for lungs, and 12.6% for hearts. The range of maximum three-dimensional centroid movement for individual patients was 1.3-24.0 mm for GTV, 2.4-7.9 mm for heart, 5.2-12.0 mm for lungs, 0.3-5.5 mm for skin markers, 2.9-10.0 mm for trachea, and 6.6-21.7 mm for diaphragm. During respiration, the centroid positions of normal structures varied relative to the centroid position of the respective GTV by 1.5-8.1 mm for heart, 2.9-9.3 mm for lungs, 1.2-9.2 mm for skin markers, 0.9-7.1 mm for trachea, and 2.7-16.4 mm for diaphragm. Conclusion: Using 4D-CT, volumetric changes, positional alterations as well as changes in the position of contoured structures relative to the GTV were observed with large variations between individual patients. Although the interpretation of 4D-CT data has considerable uncertainty because of 4D-CT artifacts, observer variations, and the limited acquisition time, the findings might have a significant impact on treatment planning.

  9. Evaluation of a 4D cone-beam CT reconstruction approach using a simulation framework.

    PubMed

    Hartl, Alexander; Yaniv, Ziv

    2009-01-01

    Current image-guided navigation systems for thoracic abdominal interventions utilize three dimensional (3D) images acquired at breath-hold. As a result they can only provide guidance at a specific point in the respiratory cycle. The intervention is thus performed in a gated manner, with the physician advancing only when the patient is at the same respiratory cycle in which the 3D image was acquired. To enable a more continuous workflow we propose to use 4D image data. We describe an approach to constructing a set of 4D images from a diagnostic CT acquired at breath-hold and a set of intraoperative cone-beam CT (CBCT) projection images acquired while the patient is freely breathing. Our approach is based on an initial reconstruction of a gated 4D CBCT data set. The 3D CBCT images for each respiratory phase are then non-rigidly registered to the diagnostic CT data. Finally the diagnostic CT is deformed based on the registration results, providing a 4D data set with sufficient quality for navigation purposes. In this work we evaluate the proposed reconstruction approach using a simulation framework. A 3D CBCT dataset of an anthropomorphic phantom is deformed using internal motion data acquired from an animal model to create a ground truth 4D CBCT image. Simulated projection images are then created from the 4D image and the known CBCT scan parameters. Finally, the original 3D CBCT and the simulated X-ray images are used as input to our reconstruction method. The resulting 4D data set is then compared to the known ground truth by normalized cross correlation(NCC). We show that the deformed diagnostic CTs are of better quality than the gated reconstructions with a mean NCC value of 0.94 versus a mean 0.81 for the reconstructions. PMID:19964143

  10. Analysis of free breathing motion using artifact reduced 4D CT image data

    NASA Astrophysics Data System (ADS)

    Ehrhardt, Jan; Werner, Rene; Frenzel, Thorsten; Lu, Wei; Low, Daniel; Handels, Heinz

    2007-03-01

    The mobility of lung tumors during the respiratory cycle is a source of error in radiotherapy treatment planning. Spatiotemporal CT data sets can be used for studying the motion of lung tumors and inner organs during the breathing cycle. We present methods for the analysis of respiratory motion using 4D CT data in high temporal resolution. An optical flow based reconstruction method was used to generate artifact-reduced 4D CT data sets of lung cancer patients. The reconstructed 4D CT data sets were segmented and the respiratory motion of tumors and inner organs was analyzed. A non-linear registration algorithm is used to calculate the velocity field between consecutive time frames of the 4D data. The resulting velocity field is used to analyze trajectories of landmarks and surface points. By this technique, the maximum displacement of any surface point is calculated, and regions with large respiratory motion are marked. To describe the tumor mobility the motion of the lung tumor center in three orthogonal directions is displayed. Estimated 3D appearance probabilities visualize the movement of the tumor during the respiratory cycle in one static image. Furthermore, correlations between trajectories of the skin surface and the trajectory of the tumor center are determined and skin regions are identified which are suitable for prediction of the internal tumor motion. The results of the motion analysis indicate that the described methods are suitable to gain insight into the spatiotemporal behavior of anatomical and pathological structures during the respiratory cycle.

  11. Resolution enhancement of lung 4D-CT via group-sparsity

    SciTech Connect

    Bhavsar, Arnav; Wu, Guorong; Shen, Dinggang; Lian, Jun

    2013-12-15

    Purpose: 4D-CT typically delivers more accurate information about anatomical structures in the lung, over 3D-CT, due to its ability to capture visual information of the lung motion across different respiratory phases. This helps to better determine the dose during radiation therapy for lung cancer. However, a critical concern with 4D-CT that substantially compromises this advantage is the low superior-inferior resolution due to less number of acquired slices, in order to control the CT radiation dose. To address this limitation, the authors propose an approach to reconstruct missing intermediate slices, so as to improve the superior-inferior resolution.Methods: In this method the authors exploit the observation that sampling information across respiratory phases in 4D-CT can be complimentary due to lung motion. The authors’ approach uses this locally complimentary information across phases in a patch-based sparse-representation framework. Moreover, unlike some recent approaches that treat local patches independently, the authors’ approach employs the group-sparsity framework that imposes neighborhood and similarity constraints between patches. This helps in mitigating the trade-off between noise robustness and structure preservation, which is an important consideration in resolution enhancement. The authors discuss the regularizing ability of group-sparsity, which helps in reducing the effect of noise and enables better structural localization and enhancement.Results: The authors perform extensive experiments on the publicly available DIR-Lab Lung 4D-CT dataset [R. Castillo, E. Castillo, R. Guerra, V. Johnson, T. McPhail, A. Garg, and T. Guerrero, “A framework for evaluation of deformable image registration spatial accuracy using large landmark point sets,” Phys. Med. Biol. 54, 1849–1870 (2009)]. First, the authors carry out empirical parametric analysis of some important parameters in their approach. The authors then demonstrate, qualitatively as well as

  12. Geometric validation of self-gating k-space-sorted 4D-MRI vs 4D-CT using a respiratory motion phantom

    SciTech Connect

    Yue, Yong Yang, Wensha; McKenzie, Elizabeth; Tuli, Richard; Wallace, Robert; Fraass, Benedick; Fan, Zhaoyang; Pang, Jianing; Deng, Zixin; Li, Debiao

    2015-10-15

    Purpose: MRI is increasingly being used for radiotherapy planning, simulation, and in-treatment-room motion monitoring. To provide more detailed temporal and spatial MR data for these tasks, we have recently developed a novel self-gated (SG) MRI technique with advantage of k-space phase sorting, high isotropic spatial resolution, and high temporal resolution. The current work describes the validation of this 4D-MRI technique using a MRI- and CT-compatible respiratory motion phantom and comparison to 4D-CT. Methods: The 4D-MRI sequence is based on a spoiled gradient echo-based 3D projection reconstruction sequence with self-gating for 4D-MRI at 3 T. Respiratory phase is resolved by using SG k-space lines as the motion surrogate. 4D-MRI images are reconstructed into ten temporal bins with spatial resolution 1.56 × 1.56 × 1.56 mm{sup 3}. A MRI-CT compatible phantom was designed to validate the performance of the 4D-MRI sequence and 4D-CT imaging. A spherical target (diameter 23 mm, volume 6.37 ml) filled with high-concentration gadolinium (Gd) gel is embedded into a plastic box (35 × 40 × 63 mm{sup 3}) and stabilized with low-concentration Gd gel. The phantom, driven by an air pump, is able to produce human-type breathing patterns between 4 and 30 respiratory cycles/min. 4D-CT of the phantom has been acquired in cine mode, and reconstructed into ten phases with slice thickness 1.25 mm. The 4D images sets were imported into a treatment planning software for target contouring. The geometrical accuracy of the 4D MRI and CT images has been quantified using target volume, flattening, and eccentricity. The target motion was measured by tracking the centroids of the spheres in each individual phase. Motion ground-truth was obtained from input signals and real-time video recordings. Results: The dynamic phantom has been operated in four respiratory rate (RR) settings, 6, 10, 15, and 20/min, and was scanned with 4D-MRI and 4D-CT. 4D-CT images have target

  13. Applying an animal model to quantify the uncertainties of an image-based 4D-CT algorithm

    NASA Astrophysics Data System (ADS)

    Pierce, Greg; Wang, Kevin; Battista, Jerry; Lee, Ting-Yim

    2012-06-01

    The purpose of this paper is to use an animal model to quantify the spatial displacement uncertainties and test the fundamental assumptions of an image-based 4D-CT algorithm in vivo. Six female Landrace cross pigs were ventilated and imaged using a 64-slice CT scanner (GE Healthcare) operating in axial cine mode. The breathing amplitude pattern of the pigs was varied by periodically crimping the ventilator gas return tube during the image acquisition. The image data were used to determine the displacement uncertainties that result from matching CT images at the same respiratory phase using normalized cross correlation (NCC) as the matching criteria. Additionally, the ability to match the respiratory phase of a 4.0 cm subvolume of the thorax to a reference subvolume using only a single overlapping 2D slice from the two subvolumes was tested by varying the location of the overlapping matching image within the subvolume and examining the effect this had on the displacement relative to the reference volume. The displacement uncertainty resulting from matching two respiratory images using NCC ranged from 0.54 ± 0.10 mm per match to 0.32 ± 0.16 mm per match in the lung of the animal. The uncertainty was found to propagate in quadrature, increasing with number of NCC matches performed. In comparison, the minimum displacement achievable if two respiratory images were matched perfectly in phase ranged from 0.77 ± 0.06 to 0.93 ± 0.06 mm in the lung. The assumption that subvolumes from separate cine scan could be matched by matching a single overlapping 2D image between to subvolumes was validated. An in vivo animal model was developed to test an image-based 4D-CT algorithm. The uncertainties associated with using NCC to match the respiratory phase of two images were quantified and the assumption that a 4.0 cm 3D subvolume can by matched in respiratory phase by matching a single 2D image from the 3D subvolume was validated. The work in this paper shows the image-based 4D-CT

  14. Comparison of 4D-microSPECT and microCT for murine cardiac function

    PubMed Central

    Befera, Nicholas T.; Badea, Cristian T.; Johnson, G. Allan

    2014-01-01

    Purpose The objective of this study was to compare a new generation of four-dimensional (4D) microSPECT with microCT for quantitative in vivo assessment of murine cardiac function. Procedures 4D isotropic cardiac images were acquired from normal C57BL/6 mice with either microSPECT at 350-micron resolution (n=6) or microCT at 88-micron resolution (n=6). One additional mouse with myocardial infarction (MI) was scanned with both modalities. Prior to imaging, mice were injected with either 99mTc -tetrofosmin for microSPECT, or a liposomal blood pool contrast agent for microCT. Segmentation of the left ventricle (LV) was performed using Vitrea (Vital Images) software, to derive global and regional function. Results Measures of global LV function between microSPECT and microCT groups were comparable (e.g. ejection fraction=71±6%-microSPECT and 68±4%-microCT). Regional functional indices (wall motion, wall thickening, regional ejection fraction) were also similar for the two modalities. In the mouse with MI, microSPECT identified a large perfusion defect that was not evident with microCT. Conclusions Despite lower spatial resolution, microSPECT was comparable to microCT in the quantitative evaluation of cardiac function. MicroSPECT offers an advantage over microCT in the ability to evaluate myocardial perfusion radiotracer distribution and function simultaneously. MicroSPECT should be considered as an alternative to microCT and MR for preclinical cardiac imaging in the mouse. PMID:24037175

  15. A hybrid reconstruction algorithm for fast and accurate 4D cone-beam CT imaginga)

    PubMed Central

    Yan, Hao; Zhen, Xin; Folkerts, Michael; Li, Yongbao; Pan, Tinsu; Cervino, Laura; Jiang, Steve B.; Jia, Xun

    2014-01-01

    Purpose: 4D cone beam CT (4D-CBCT) has been utilized in radiation therapy to provide 4D image guidance in lung and upper abdomen area. However, clinical application of 4D-CBCT is currently limited due to the long scan time and low image quality. The purpose of this paper is to develop a new 4D-CBCT reconstruction method that restores volumetric images based on the 1-min scan data acquired with a standard 3D-CBCT protocol. Methods: The model optimizes a deformation vector field that deforms a patient-specific planning CT (p-CT), so that the calculated 4D-CBCT projections match measurements. A forward-backward splitting (FBS) method is invented to solve the optimization problem. It splits the original problem into two well-studied subproblems, i.e., image reconstruction and deformable image registration. By iteratively solving the two subproblems, FBS gradually yields correct deformation information, while maintaining high image quality. The whole workflow is implemented on a graphic-processing-unit to improve efficiency. Comprehensive evaluations have been conducted on a moving phantom and three real patient cases regarding the accuracy and quality of the reconstructed images, as well as the algorithm robustness and efficiency. Results: The proposed algorithm reconstructs 4D-CBCT images from highly under-sampled projection data acquired with 1-min scans. Regarding the anatomical structure location accuracy, 0.204 mm average differences and 0.484 mm maximum difference are found for the phantom case, and the maximum differences of 0.3–0.5 mm for patients 1–3 are observed. As for the image quality, intensity errors below 5 and 20 HU compared to the planning CT are achieved for the phantom and the patient cases, respectively. Signal-noise-ratio values are improved by 12.74 and 5.12 times compared to results from FDK algorithm using the 1-min data and 4-min data, respectively. The computation time of the algorithm on a NVIDIA GTX590 card is 1–1.5 min per phase

  16. A hybrid reconstruction algorithm for fast and accurate 4D cone-beam CT imaging

    SciTech Connect

    Yan, Hao; Folkerts, Michael; Jiang, Steve B. E-mail: steve.jiang@UTSouthwestern.edu; Jia, Xun E-mail: steve.jiang@UTSouthwestern.edu; Zhen, Xin; Li, Yongbao; Pan, Tinsu; Cervino, Laura

    2014-07-15

    Purpose: 4D cone beam CT (4D-CBCT) has been utilized in radiation therapy to provide 4D image guidance in lung and upper abdomen area. However, clinical application of 4D-CBCT is currently limited due to the long scan time and low image quality. The purpose of this paper is to develop a new 4D-CBCT reconstruction method that restores volumetric images based on the 1-min scan data acquired with a standard 3D-CBCT protocol. Methods: The model optimizes a deformation vector field that deforms a patient-specific planning CT (p-CT), so that the calculated 4D-CBCT projections match measurements. A forward-backward splitting (FBS) method is invented to solve the optimization problem. It splits the original problem into two well-studied subproblems, i.e., image reconstruction and deformable image registration. By iteratively solving the two subproblems, FBS gradually yields correct deformation information, while maintaining high image quality. The whole workflow is implemented on a graphic-processing-unit to improve efficiency. Comprehensive evaluations have been conducted on a moving phantom and three real patient cases regarding the accuracy and quality of the reconstructed images, as well as the algorithm robustness and efficiency. Results: The proposed algorithm reconstructs 4D-CBCT images from highly under-sampled projection data acquired with 1-min scans. Regarding the anatomical structure location accuracy, 0.204 mm average differences and 0.484 mm maximum difference are found for the phantom case, and the maximum differences of 0.3–0.5 mm for patients 1–3 are observed. As for the image quality, intensity errors below 5 and 20 HU compared to the planning CT are achieved for the phantom and the patient cases, respectively. Signal-noise-ratio values are improved by 12.74 and 5.12 times compared to results from FDK algorithm using the 1-min data and 4-min data, respectively. The computation time of the algorithm on a NVIDIA GTX590 card is 1–1.5 min per phase

  17. Simultaneous motion estimation and image reconstruction (SMEIR) for 4D cone-beam CT

    SciTech Connect

    Wang, Jing; Gu, Xuejun

    2013-10-15

    Purpose: Image reconstruction and motion model estimation in four-dimensional cone-beam CT (4D-CBCT) are conventionally handled as two sequential steps. Due to the limited number of projections at each phase, the image quality of 4D-CBCT is degraded by view aliasing artifacts, and the accuracy of subsequent motion modeling is decreased by the inferior 4D-CBCT. The objective of this work is to enhance both the image quality of 4D-CBCT and the accuracy of motion model estimation with a novel strategy enabling simultaneous motion estimation and image reconstruction (SMEIR).Methods: The proposed SMEIR algorithm consists of two alternating steps: (1) model-based iterative image reconstruction to obtain a motion-compensated primary CBCT (m-pCBCT) and (2) motion model estimation to obtain an optimal set of deformation vector fields (DVFs) between the m-pCBCT and other 4D-CBCT phases. The motion-compensated image reconstruction is based on the simultaneous algebraic reconstruction technique (SART) coupled with total variation minimization. During the forward- and backprojection of SART, measured projections from an entire set of 4D-CBCT are used for reconstruction of the m-pCBCT by utilizing the updated DVF. The DVF is estimated by matching the forward projection of the deformed m-pCBCT and measured projections of other phases of 4D-CBCT. The performance of the SMEIR algorithm is quantitatively evaluated on a 4D NCAT phantom. The quality of reconstructed 4D images and the accuracy of tumor motion trajectory are assessed by comparing with those resulting from conventional sequential 4D-CBCT reconstructions (FDK and total variation minimization) and motion estimation (demons algorithm). The performance of the SMEIR algorithm is further evaluated by reconstructing a lung cancer patient 4D-CBCT.Results: Image quality of 4D-CBCT is greatly improved by the SMEIR algorithm in both phantom and patient studies. When all projections are used to reconstruct a 3D-CBCT by FDK, motion

  18. Acquisition of 4D DIC microscopic data to determine cell contacts in Caenorhabditis elegans embryos.

    PubMed

    Walston, Timothy; Hardin, Jeff

    2010-12-01

    The Caenorhabditis elegans embryo is particularly amenable to microscopy and embryological studies because of its short developmental time, transparent shell, and nonpigmented cells. Acquisition of stacks of images throughout the thickness of the embryo over time is a crucial method for identifying the positions and contacts between cells. Such four-dimensional (4D) microscopy is a routine tool in laboratories that study early C. elegans development. Differential interference contrast (DIC) microscopy is the focus here because of its broad availability, common use for C. elegans imaging, and wide applicability to microscopic analysis of embryos of other organisms. This protocol describes the use of a custom script within μManager's Beanshell scripting language. The script is helpful for reducing the number of shutter open/close events during 4D acquisition. PMID:21123428

  19. SU-E-J-120: Comparing 4D CT Computed Ventilation to Lung Function Measured with Hyperpolarized Xenon-129 MRI

    SciTech Connect

    Neal, B; Chen, Q

    2015-06-15

    Purpose: To correlate ventilation parameters computed from 4D CT to ventilation, profusion, and gas exchange measured with hyperpolarized Xenon-129 MRI for a set of lung cancer patients. Methods: Hyperpolarized Xe-129 MRI lung scans were acquired for lung cancer patients, before and after radiation therapy, measuring ventilation, perfusion, and gas exchange. In the standard clinical workflow, these patients also received 4D CT scans before treatment. Ventilation was computed from 4D CT using deformable image registration (DIR). All phases of the 4D CT scan were registered using a B-spline deformable registration. Ventilation at the voxel level was then computed for each phase based on a Jacobian volume expansion metric, yielding phase sorted ventilation images. Ventilation based upon 4D CT and Xe-129 MRI were co-registered, allowing qualitative visual comparison and qualitative comparison via the Pearson correlation coefficient. Results: Analysis shows a weak correlation between hyperpolarized Xe-129 MRI and 4D CT DIR ventilation, with a Pearson correlation coefficient of 0.17 to 0.22. Further work will refine the DIR parameters to optimize the correlation. The weak correlation could be due to the limitations of 4D CT, registration algorithms, or the Xe-129 MRI imaging. Continued development will refine parameters to optimize correlation. Conclusion: Current analysis yields a minimal correlation between 4D CT DIR and Xe-129 MRI ventilation. Funding provided by the 2014 George Amorino Pilot Grant in Radiation Oncology at the University of Virginia.

  20. Clinical Utility of 4D FDG-PET/CT Scans in Radiation Treatment Planning

    SciTech Connect

    Aristophanous, Michalis; Sher, David J.; Allen, Aaron M.; Larson, Elysia; Chen, Aileen B.

    2012-01-01

    Purpose: The potential role of four-dimensional (4D) positron emission tomography (PET)/computed tomography (CT) in radiation treatment planning, relative to standard three-dimensional (3D) PET/CT, was examined. Methods and Materials: Ten patients with non-small-cell lung cancer had sequential 3D and 4D [{sup 18}F]fluorodeoxyglucose PET/CT scans in the treatment position prior to radiation therapy. The gross tumor volume and involved lymph nodes were contoured on the PET scan by use of three different techniques: manual contouring by an experienced radiation oncologist using a predetermined protocol; a technique with a constant threshold of standardized uptake value (SUV) greater than 2.5; and an automatic segmentation technique. For each technique, the tumor volume was defined on the 3D scan (VOL3D) and on the 4D scan (VOL4D) by combining the volume defined on each of the five breathing phases individually. The range of tumor motion and the location of each lesion were also recorded, and their influence on the differences observed between VOL3D and VOL4D was investigated. Results: We identified and analyzed 22 distinct lesions, including 9 primary tumors and 13 mediastinal lymph nodes. Mean VOL4D was larger than mean VOL3D with all three techniques, and the difference was statistically significant (p < 0.01). The range of tumor motion and the location of the tumor affected the magnitude of the difference. For one case, all three tumor definition techniques identified volume of moderate uptake of approximately 1 mL in the hilar region on the 4D scan (SUV maximum, 3.3) but not on the 3D scan (SUV maximum, 2.3). Conclusions: In comparison to 3D PET, 4D PET may better define the full physiologic extent of moving tumors and improve radiation treatment planning for lung tumors. In addition, reduction of blurring from free-breathing images may reveal additional information regarding regional disease.

  1. Feature Guided Motion Artifact Reduction with Structure-Awareness in 4D CT Images

    PubMed Central

    Han, Dongfeng; Bayouth, John; Song, Qi; Bhatia, Sudershan; Sonka, Milan; Wu, Xiaodong

    2011-01-01

    In this paper, we propose a novel method to reduce the magnitude of 4D CT artifacts by stitching two images with a data-driven regularization constrain, which helps preserve the local anatomy structures. Our method first computes an interface seam for the stitching in the overlapping region of the first image, which passes through the “smoothest” region, to reduce the structure complexity along the stitching interface. Then, we compute the displacements of the seam by matching the corresponding interface seam in the second image. We use sparse 3D features as the structure cues to guide the seam matching, in which a regularization term is incorporated to keep the structure consistency. The energy function is minimized by solving a multiple-label problem in Markov Random Fields with an anatomical structure preserving regularization term. The displacements are propagated to the rest of second image and the two image are stitched along the interface seams based on the computed displacement field. The method was tested on both simulated data and clinical 4D CT images. The experiments on simulated data demonstrated that the proposed method was able to reduce the landmark distance error on average from 2.9 mm to 1.3 mm, outperforming the registration-based method by about 55%. For clinical 4D CT image data, the image quality was evaluated by three medical experts, and all identified much fewer artifacts from the resulting images by our method than from those by the compared method. PMID:22058647

  2. Registration based super-resolution reconstruction for lung 4D-CT.

    PubMed

    Wu, Xiuxiu; Xiao, Shan; Zhang, Yu

    2014-01-01

    Lung 4D-CT plays an important role in lung cancer radiotherapy for tumor localization and treatment planning. In lung 4D-CT data, the resolution in the slice direction is often much lower than the in-plane resolution. For multi-plane display, isotropic resolution is necessary, but the commonly used interpolation operation will blur the images. In this paper, we present a registration based method for super resolution enhancement of the 4D-CT multi-plane images. Our working premise is that the low-resolution images of different phases at the corresponding position can be regarded as input "frames" to reconstruct high resolution images. First, we employ the Demons registration algorithm to estimate the motion field between different "frames". Then, the projections onto convex sets (POCS) approach is employed to reconstruction high-resolution lung images. We show that our method can get clearer lung images and enhance image structure, compared with the cubic spline interpolation and back projection method. PMID:25570484

  3. 4D cone-beam CT reconstruction using multi-organ meshes for sliding motion modeling.

    PubMed

    Zhong, Zichun; Gu, Xuejun; Mao, Weihua; Wang, Jing

    2016-02-01

    A simultaneous motion estimation and image reconstruction (SMEIR) strategy was proposed for 4D cone-beam CT (4D-CBCT) reconstruction and showed excellent results in both phantom and lung cancer patient studies. In the original SMEIR algorithm, the deformation vector field (DVF) was defined on voxel grid and estimated by enforcing a global smoothness regularization term on the motion fields. The objective of this work is to improve the computation efficiency and motion estimation accuracy of SMEIR for 4D-CBCT through developing a multi-organ meshing model. Feature-based adaptive meshes were generated to reduce the number of unknowns in the DVF estimation and accurately capture the organ shapes and motion. Additionally, the discontinuity in the motion fields between different organs during respiration was explicitly considered in the multi-organ mesh model. This will help with the accurate visualization and motion estimation of the tumor on the organ boundaries in 4D-CBCT. To further improve the computational efficiency, a GPU-based parallel implementation was designed. The performance of the proposed algorithm was evaluated on a synthetic sliding motion phantom, a 4D NCAT phantom, and four lung cancer patients. The proposed multi-organ mesh based strategy outperformed the conventional Feldkamp-Davis-Kress, iterative total variation minimization, original SMEIR and single meshing method based on both qualitative and quantitative evaluations. PMID:26758496

  4. 4D cone-beam CT reconstruction using multi-organ meshes for sliding motion modeling

    NASA Astrophysics Data System (ADS)

    Zhong, Zichun; Gu, Xuejun; Mao, Weihua; Wang, Jing

    2016-02-01

    A simultaneous motion estimation and image reconstruction (SMEIR) strategy was proposed for 4D cone-beam CT (4D-CBCT) reconstruction and showed excellent results in both phantom and lung cancer patient studies. In the original SMEIR algorithm, the deformation vector field (DVF) was defined on voxel grid and estimated by enforcing a global smoothness regularization term on the motion fields. The objective of this work is to improve the computation efficiency and motion estimation accuracy of SMEIR for 4D-CBCT through developing a multi-organ meshing model. Feature-based adaptive meshes were generated to reduce the number of unknowns in the DVF estimation and accurately capture the organ shapes and motion. Additionally, the discontinuity in the motion fields between different organs during respiration was explicitly considered in the multi-organ mesh model. This will help with the accurate visualization and motion estimation of the tumor on the organ boundaries in 4D-CBCT. To further improve the computational efficiency, a GPU-based parallel implementation was designed. The performance of the proposed algorithm was evaluated on a synthetic sliding motion phantom, a 4D NCAT phantom, and four lung cancer patients. The proposed multi-organ mesh based strategy outperformed the conventional Feldkamp-Davis-Kress, iterative total variation minimization, original SMEIR and single meshing method based on both qualitative and quantitative evaluations.

  5. Denoising of 4D Cardiac Micro-CT Data Using Median-Centric Bilateral Filtration

    PubMed Central

    Clark, D.; Johnson, G.A.; Badea, C.T.

    2012-01-01

    Bilateral filtration has proven an effective tool for denoising CT data. The classic filter utilizes Gaussian domain and range weighting functions in 2D. More recently, other distributions have yielded more accurate results in specific applications, and the bilateral filtration framework has been extended to higher dimensions. In this study, brute-force optimization is employed to evaluate the use of several alternative distributions for both domain and range weighting: Andrew's Sine Wave, El Fallah Ford, Gaussian, Flat, Lorentzian, Huber's Minimax, Tukey's Bi-weight, and Cosine. Two variations on the classic bilateral filter which use median filtration to reduce bias in range weights are also investigated: median-centric and hybrid bilateral filtration. Using the 4D MOBY mouse phantom reconstructed with noise (stdev. ~ 65 HU), hybrid bilateral filtration, a combination of the classic and median-centric filters, with Flat domain and range weighting is shown to provide optimal denoising results (PSNRs: 31.69, classic; 31.58 median-centric; 32.25, hybrid). To validate these phantom studies, the optimal filters are also applied to in vivo, 4D cardiac micro-CT data acquired in the mouse. In a constant region of the left ventricle, hybrid bilateral filtration with Flat domain and range weighting is shown to provide optimal smoothing (stdev: original, 72.2 HU; classic, 20.3 HU; median-centric, 24.1 HU; hybrid, 15.9 HU). While the optimal results were obtained using 4D filtration, the 3D hybrid filter is ultimately recommended for denoising 4D cardiac micro-CT data because it is more computationally tractable and less prone to artifacts (MOBY PSNR: 32.05; left ventricle stdev: 20.5 HU). PMID:24386540

  6. SU-C-9A-06: The Impact of CT Image Used for Attenuation Correction in 4D-PET

    SciTech Connect

    Cui, Y; Bowsher, J; Yan, S; Cai, J; Das, S; Yin, F

    2014-06-01

    Purpose: To evaluate the appropriateness of using 3D non-gated CT image for attenuation correction (AC) in a 4D-PET (gated PET) imaging protocol used in radiotherapy treatment planning simulation. Methods: The 4D-PET imaging protocol in a Siemens PET/CT simulator (Biograph mCT, Siemens Medical Solutions, Hoffman Estates, IL) was evaluated. CIRS Dynamic Thorax Phantom (CIRS Inc., Norfolk, VA) with a moving glass sphere (8 mL) in the middle of its thorax portion was used in the experiments. The glass was filled with {sup 18}F-FDG and was in a longitudinal motion derived from a real patient breathing pattern. Varian RPM system (Varian Medical Systems, Palo Alto, CA) was used for respiratory gating. Both phase-gating and amplitude-gating methods were tested. The clinical imaging protocol was modified to use three different CT images for AC in 4D-PET reconstruction: first is to use a single-phase CT image to mimic actual clinical protocol (single-CT-PET); second is to use the average intensity projection CT (AveIP-CT) derived from 4D-CT scanning (AveIP-CT-PET); third is to use 4D-CT image to do the phase-matched AC (phase-matching- PET). Maximum SUV (SUVmax) and volume of the moving target (glass sphere) with threshold of 40% SUVmax were calculated for comparison between 4D-PET images derived with different AC methods. Results: The SUVmax varied 7.3%±6.9% over the breathing cycle in single-CT-PET, compared to 2.5%±2.8% in AveIP-CT-PET and 1.3%±1.2% in phasematching PET. The SUVmax in single-CT-PET differed by up to 15% from those in phase-matching-PET. The target volumes measured from single- CT-PET images also presented variations up to 10% among different phases of 4D PET in both phase-gating and amplitude-gating experiments. Conclusion: Attenuation correction using non-gated CT in 4D-PET imaging is not optimal process for quantitative analysis. Clinical 4D-PET imaging protocols should consider phase-matched 4D-CT image if available to achieve better accuracy.

  7. Impact of CT attenuation correction method on quantitative respiratory-correlated (4D) PET/CT imaging

    SciTech Connect

    Nyflot, Matthew J.; Lee, Tzu-Cheng; Alessio, Adam M.; Kinahan, Paul E.; Wollenweber, Scott D.; Stearns, Charles W.; Bowen, Stephen R.

    2015-01-15

    Purpose: Respiratory-correlated positron emission tomography (PET/CT) 4D PET/CT is used to mitigate errors from respiratory motion; however, the optimal CT attenuation correction (CTAC) method for 4D PET/CT is unknown. The authors performed a phantom study to evaluate the quantitative performance of CTAC methods for 4D PET/CT in the ground truth setting. Methods: A programmable respiratory motion phantom with a custom movable insert designed to emulate a lung lesion and lung tissue was used for this study. The insert was driven by one of five waveforms: two sinusoidal waveforms or three patient-specific respiratory waveforms. 3DPET and 4DPET images of the phantom under motion were acquired and reconstructed with six CTAC methods: helical breath-hold (3DHEL), helical free-breathing (3DMOT), 4D phase-averaged (4DAVG), 4D maximum intensity projection (4DMIP), 4D phase-matched (4DMATCH), and 4D end-exhale (4DEXH) CTAC. Recovery of SUV{sub max}, SUV{sub mean}, SUV{sub peak}, and segmented tumor volume was evaluated as RC{sub max}, RC{sub mean}, RC{sub peak}, and RC{sub vol}, representing percent difference relative to the static ground truth case. Paired Wilcoxon tests and Kruskal–Wallis ANOVA were used to test for significant differences. Results: For 4DPET imaging, the maximum intensity projection CTAC produced significantly more accurate recovery coefficients than all other CTAC methods (p < 0.0001 over all metrics). Over all motion waveforms, ratios of 4DMIP CTAC recovery were 0.2 ± 5.4, −1.8 ± 6.5, −3.2 ± 5.0, and 3.0 ± 5.9 for RC{sub max}, RC{sub peak}, RC{sub mean}, and RC{sub vol}. In comparison, recovery coefficients for phase-matched CTAC were −8.4 ± 5.3, −10.5 ± 6.2, −7.6 ± 5.0, and −13.0 ± 7.7 for RC{sub max}, RC{sub peak}, RC{sub mean}, and RC{sub vol}. When testing differences between phases over all CTAC methods and waveforms, end-exhale phases were significantly more accurate (p = 0.005). However, these differences were driven by

  8. Assessment of a quantitative metric for 4D CT artifact evaluation by observer consensus.

    PubMed

    Castillo, Sarah J; Castillo, Richard; Balter, Peter; Pan, Tinsu; Ibbott, Geoffrey; Hobbs, Brian; Yuan, Ying; Guerrero, Thomas

    2014-01-01

    The benefits of four-dimensional computed tomography (4D CT) are limited by the presence of artifacts that remain difficult to quantify. A correlation-based metric previously proposed for ciné 4D CT artifact identification was further validated as an independent artifact evaluator by using a novel qualitative assessment featuring a group of observers reaching a consensus decision on artifact location and magnitude. The consensus group evaluated ten ciné 4D CT scans for artifacts over each breathing phase of coronal lung views assuming one artifact per couch location. Each artifact was assigned a magnitude score of 1-5, 1 indicating lowest severity and 5 indicating highest severity. Consensus group results served as the ground truth for assessment of the correlation metric. The ten patients were split into two cohorts; cohort 1 generated an artifact identification threshold derived from receiver operating characteristic analysis using the Youden Index, while cohort 2 generated sensitivity and specificity values from application of the artifact threshold. The Pearson correlation coefficient was calculated between the correlation metric values and the consensus group scores for both cohorts. The average sensitivity and specificity values found with application of the artifact threshold were 0.703 and 0.476, respectively. The correlation coefficients of artifact magnitudes for cohort 1 and 2 were 0.80 and 0.61, respectively, (p < 0.001 for both); these correlation coefficients included a few scans with only two of the five possible magnitude scores. Artifact incidence was associated with breathing phase (p < 0.002), with presentation less likely near maximum exhale. Overall, the correlation metric allowed accurate and automated artifact identification. The consensus group evaluation resulted in efficient qualitative scoring, reduced interobserver variation, and provided consistent identification of artifact location and magnitudes. PMID:24892346

  9. Registration-based segmentation of murine 4D cardiac micro-CT data using symmetric normalization

    NASA Astrophysics Data System (ADS)

    Clark, Darin; Badea, Alexandra; Liu, Yilin; Johnson, G. Allan; Badea, Cristian T.

    2012-10-01

    Micro-CT can play an important role in preclinical studies of cardiovascular disease because of its high spatial and temporal resolution. Quantitative analysis of 4D cardiac images requires segmentation of the cardiac chambers at each time point, an extremely time consuming process if done manually. To improve throughput this study proposes a pipeline for registration-based segmentation and functional analysis of 4D cardiac micro-CT data in the mouse. Following optimization and validation using simulations, the pipeline was applied to in vivo cardiac micro-CT data corresponding to ten cardiac phases acquired in C57BL/6 mice (n = 5). After edge-preserving smoothing with a novel adaptation of 4D bilateral filtration, one phase within each cardiac sequence was manually segmented. Deformable registration was used to propagate these labels to all other cardiac phases for segmentation. The volumes of each cardiac chamber were calculated and used to derive stroke volume, ejection fraction, cardiac output, and cardiac index. Dice coefficients and volume accuracies were used to compare manual segmentations of two additional phases with their corresponding propagated labels. Both measures were, on average, >0.90 for the left ventricle and >0.80 for the myocardium, the right ventricle, and the right atrium, consistent with trends in inter- and intra-segmenter variability. Segmentation of the left atrium was less reliable. On average, the functional metrics of interest were underestimated by 6.76% or more due to systematic label propagation errors around atrioventricular valves; however, execution of the pipeline was 80% faster than performing analogous manual segmentation of each phase.

  10. Assessment of regional ventilation and deformation using 4D-CT imaging for healthy human lungs during tidal breathing.

    PubMed

    Jahani, Nariman; Choi, Sanghun; Choi, Jiwoong; Iyer, Krishna; Hoffman, Eric A; Lin, Ching-Long

    2015-11-15

    This study aims to assess regional ventilation, nonlinearity, and hysteresis of human lungs during dynamic breathing via image registration of four-dimensional computed tomography (4D-CT) scans. Six healthy adult humans were studied by spiral multidetector-row CT during controlled tidal breathing as well as during total lung capacity and functional residual capacity breath holds. Static images were utilized to contrast static vs. dynamic (deep vs. tidal) breathing. A rolling-seal piston system was employed to maintain consistent tidal breathing during 4D-CT spiral image acquisition, providing required between-breath consistency for physiologically meaningful reconstructed respiratory motion. Registration-derived variables including local air volume and anisotropic deformation index (ADI, an indicator of preferential deformation in response to local force) were employed to assess regional ventilation and lung deformation. Lobar distributions of air volume change during tidal breathing were correlated with those of deep breathing (R(2) ≈ 0.84). Small discrepancies between tidal and deep breathing were shown to be likely due to different distributions of air volume change in the left and the right lungs. We also demonstrated an asymmetric characteristic of flow rate between inhalation and exhalation. With ADI, we were able to quantify nonlinearity and hysteresis of lung deformation that can only be captured in dynamic images. Nonlinearity quantified by ADI is greater during inhalation, and it is stronger in the lower lobes (P < 0.05). Lung hysteresis estimated by the difference of ADI between inhalation and exhalation is more significant in the right lungs than that in the left lungs. PMID:26316512

  11. SU-E-J-241: Creation of Ventilation CT From Daily 4D CTs Or 4D Conebeam CTs Acquired During IGRT for Thoracic Cancers

    SciTech Connect

    Tai, A; Ahunbay, E; Li, X

    2014-06-01

    Purpose: To develop a method to create ventilation CTs from daily 4D CTs or 4D KV conebeam CTs (4DCBCT) acquired during image-guided radiation therapy (IGRT) for thoracic tumors, and to explore the potential for using the ventilation CTs as a means for early detection of lung injury during radiation treatment. Methods: 4DCT acquired using an in-room CT (CTVision, Siemens) and 4DCBCT acquired using the X-ray Volume Imaging (XVI) system (Infinity, Elekta) for representative lung cancer patients were analyzed. These 4D data sets were sorted into 10 phase images. A newly-available deformable image registration tool (ADMIRE, Elekta) is used to deform the phase images at the end of exhale (EE) to the phase images at the end of inhale (EI). The lung volumes at EI and EE were carefully contoured using an intensity-based auto-contour tool and then manually edited. The ventilation images were calculated from the variations of CT numbers of those voxels masked by the lung contour at EI between the registered phase images. The deformable image registration is also performed between the daily 4D images and planning 4DCT, and the resulting deformable field vector (DFV) is used to deform the planning doses to the daily images by an in-house Matlab program. Results: The ventilation images were successfully created. The tide volumes calculated using the ventilation images agree with those measured through volume difference of contours at EE and EI, indicating the accuracy of ventilation images. The association between the delivered doses and the change of lung ventilation from the daily ventilation CTs is identified. Conclusions: A method to create the ventilation CT using daily 4DCTs or 4D KV conebeam CTs was developed and demonstrated.

  12. Tracking the motion trajectories of junction structures in 4D CT images of the lung

    NASA Astrophysics Data System (ADS)

    Xiong, Guanglei; Chen, Chuangzhen; Chen, Jianzhou; Xie, Yaoqin; Xing, Lei

    2012-08-01

    Respiratory motion poses a major challenge in lung radiotherapy. Based on 4D CT images, a variety of intensity-based deformable registration techniques have been proposed to study the pulmonary motion. However, the accuracy achievable with these approaches can be sub-optimal because the deformation is defined globally in space. Therefore, the accuracy of the alignment of local structures may be compromised. In this work, we propose a novel method to detect a large collection of natural junction structures in the lung and use them as the reliable markers to track the lung motion. Specifically, detection of the junction centers and sizes is achieved by analysis of local shape profiles on one segmented image. To track the temporal trajectory of a junction, the image intensities within a small region of interest surrounding the center are selected as its signature. Under the assumption of the cyclic motion, we describe the trajectory by a closed B-spline curve and search for the control points by maximizing a metric of combined correlation coefficients. Local extrema are suppressed by improving the initial conditions using random walks from pair-wise optimizations. Several descriptors are introduced to analyze the motion trajectories. Our method was applied to 13 real 4D CT images. More than 700 junctions in each case are detected with an average positive predictive value of greater than 90%. The average tracking error between automated and manual tracking is sub-voxel and smaller than the published results using the same set of data.

  13. Reconstruction of 4D-CT data sets acquired during free breathing for the analysis of respiratory motion

    NASA Astrophysics Data System (ADS)

    Ehrhardt, Jan; Werner, Rene; Frenzel, Thorsten; Säring, Dennis; Lu, Wei; Low, Daniel; Handels, Heinz

    2006-03-01

    Respiratory motion is a significant source of error in radiotherapy treatment planning. 4D-CT data sets can be useful to measure the impact of organ motion caused by breathing. But modern CT scanners can only scan a limited region of the body simultaneously and patients have to be scanned in segments consisting of multiple slices. For studying free breathing motion multislice CT scans can be collected simultaneously with digital spirometry over several breathing cycles. The 4D data set is assembled by sorting the free breathing multislice CT scans according to the couch position and the tidal volume. But artifacts can occur because there are no data segments for exactly the same tidal volume and all couch positions. We present an optical flow based method for the reconstruction of 4D-CT data sets from multislice CT scans, which are collected simultaneously with digital spirometry. The optical flow between the scans is estimated by a non-linear registration method. The calculated velocity field is used to reconstruct a 4D-CT data set by interpolating data at user-defined tidal volumes. By this technique, artifacts can be reduced significantly. The reconstructed 4D-CT data sets are used for studying inner organ motion during the respiratory cycle. The procedures described were applied to reconstruct 4D-CT data sets for four tumour patients who have been scanned during free breathing. The reconstructed 4D data sets were used to quantify organ displacements and to visualize the abdominothoracic organ motion.

  14. Reference geometry-based detection of (4D-)CT motion artifacts: a feasibility study

    NASA Astrophysics Data System (ADS)

    Werner, René; Gauer, Tobias

    2015-03-01

    Respiration-correlated computed tomography (4D or 3D+t CT) can be considered as standard of care in radiation therapy treatment planning for lung and liver lesions. The decision about an application of motion management devices and the estimation of patient-specific motion effects on the dose distribution relies on precise motion assessment in the planning 4D CT data { which is impeded in case of CT motion artifacts. The development of image-based/post-processing approaches to reduce motion artifacts would benefit from precise detection and localization of the artifacts. Simple slice-by-slice comparison of intensity values and threshold-based analysis of related metrics suffer from- depending on the threshold- high false-positive or -negative rates. In this work, we propose exploiting prior knowledge about `ideal' (= artifact free) reference geometries to stabilize metric-based artifact detection by transferring (multi-)atlas-based concepts to this specific task. Two variants are introduced and evaluated: (S1) analysis and comparison of warped atlas data obtained by repeated non-linear atlas-to-patient registration with different levels of regularization; (S2) direct analysis of vector field properties (divergence, curl magnitude) of the atlas-to-patient transformation. Feasibility of approaches (S1) and (S2) is evaluated by motion-phantom data and intra-subject experiments (four patients) as well as - adopting a multi-atlas strategy- inter-subject investigations (twelve patients involved). It is demonstrated that especially sorting/double structure artifacts can be precisely detected and localized by (S1). In contrast, (S2) suffers from high false positive rates.

  15. Image-domain motion compensated time resolved 4D cardiac CT

    NASA Astrophysics Data System (ADS)

    Taguchi, Katsuyuki; Sun, Zhihui; Segars, W. Paul; Fishman, Elliot K.; Tsui, Benjamin M. W.

    2007-03-01

    Two major problems with the current electrocardiogram-gated cardiac computed tomography (CT) imaging technique are a large patient radiation dose (10-15 mSv) and insufficient temporal resolution (83-165 ms). Our long-term goal is to develop new time resolved and low dose cardiac CT imaging techniques that consist of image reconstruction algorithms and estimation methods of the time-dependent motion vector field (MVF) of the heart from the acquired CT data. Toward this goal, we developed a method that estimates the 2D components of the MVF from a sequence of cardiac CT images and used it to "reconstruct" cardiac images at rapidly moving phases. First, two sharp image frames per heart beat (cycle) obtained at slow motion phases (i.e., mid-diastole and end-systole) were chosen. Nodes were coarsely placed among images; and the temporal motion of each node was modeled by B-splines. Our cost function consisted of 3 terms: mean-squared-error with the block-matching, and smoothness constraints in space and time. The time-dependent MVF was estimated by minimizing the cost function. We then warped images at slow motion phases using the estimated vector fields to "reconstruct" images at rapidly moving phase. The warping algorithm was evaluated using true time-dependent motion vector fields and images both provided by the NCAT phantom program. Preliminary results from ongoing quantitative and qualitative evaluation using the 4D NCAT phantom and patient data are encouraging. Major motion artifact is much reduced. We conclude the new image-based motion estimation technique is an important step toward the development of the new cardiac CT imaging techniques.

  16. SU-E-J-207: Assessing the Validity of 4D-CT Based Target Volumes and Free Breathing CBCT Localization in Lung Stereotactic Ablative Radiation Therapy (SABR)

    SciTech Connect

    Badkul, R; Pokhrel, D; Jiang, H; Park, J; Wang, F; Kumar, P

    2014-06-01

    Purpose: Four-dimensional-computed-tomography(4D-CT) imaging for target-volume delineation and cone-beam-tomography(CBCT) for treatment localization are widely utilized in lung-SABR.Aim of this study was to perform a quantitative-assessment and inter-comparison of Internal-targetvolumes( ITV) drawn on various phases of breathing-cycle 4D-CT-scans, Maximum-intensity-projection(MIP), average-intensity-projection(AIP)and static CT-scans of lung-motion-phantom to simulate lung-SABR patient geometry. We also analyzed and compared the ITVs drawn on freebreathing- CBCT. Materials and Methods: 4D-CT-scans were acquired on Philips big-bore 16slice CT and Bellows-respiratory monitoring-system using retrospective phase-binning method. Each respiratory cycle divided into 10-phases. Quasar-Phantom with lung-inserts and 3cm-diameter nylonball to simulate tumor and was placed on respiratory-motion-platform for 4D-CT and CBCT-acquisition. Amplitudes of motions: 0.5,1.0,2.0,3.0cm in superior-inferior direction with breathing-cycle time of 6,5,4,6sec, respectively used.4D-CTs with 10-phases(0%to90%)for each excursion-set and 3D-CT for static-phantom exported to iPlan treatment-planningsystem( TPS).Tumor-volumes delineated in all phases of 4D-CT, MIP,AIP,CBCT scans using fixed-HU-threshold(−500to1000)values automatically.For each 4D-dataset ITV obtained by unifying the tumorcontours on all phases.CBCT-ITV-volumes were drawn in Eclipse-TPS. Results: Mean volume of tumor contours for all phases compared with static 3D-CT were 0.62±0.08%, 1.67±0.26%, 4.77±0.54% and 9.27±1.23% for 0.5cm,1cm,2cm,3cm excursions respectively. Differences of mean Union-ITV with MIP-ITV were close(≤2.4%).Mean Union-ITV from expected-theoretical values differed from −4.9% to 3.8%.Union-ITV and MIP-ITV were closer within 2.3%. AIP-ITVs were underestimated from 14 to 32% compared to union-ITV for all motion datasets. Differences of −5.9% to −44% and −5% to 6.7% for CBCT-ITV from MIP-ITV and AIP

  17. Spatial-temporal total variation regularization (STTVR) for 4D-CT reconstruction

    NASA Astrophysics Data System (ADS)

    Wu, Haibo; Maier, Andreas; Fahrig, Rebecca; Hornegger, Joachim

    2012-03-01

    Four dimensional computed tomography (4D-CT) is very important for treatment planning in thorax or abdomen area, e.g. for guiding radiation therapy planning. The respiratory motion makes the reconstruction problem illposed. Recently, compressed sensing theory was introduced. It uses sparsity as a prior to solve the problem and improves image quality considerably. However, the images at each phase are reconstructed individually. The correlations between neighboring phases are not considered in the reconstruction process. In this paper, we propose the spatial-temporal total variation regularization (STTVR) method which not only employs the sparsity in the spatial domain but also in the temporal domain. The algorithm is validated with XCAT thorax phantom. The Euclidean norm of the reconstructed image and ground truth is calculated for evaluation. The results indicate that our method improves the reconstruction quality by more than 50% compared to standard ART.

  18. Adaptive patch-based POCS approach for super resolution reconstruction of 4D-CT lung data

    NASA Astrophysics Data System (ADS)

    Wang, Tingting; Cao, Lei; Yang, Wei; Feng, Qianjin; Chen, Wufan; Zhang, Yu

    2015-08-01

    Image enhancement of lung four-dimensional computed tomography (4D-CT) data is highly important because image resolution remains a crucial point in lung cancer radiotherapy. In this paper, we proposed a method for lung 4D-CT super resolution (SR) by using an adaptive-patch-based projection onto convex sets (POCS) approach, which is in contrast with the global POCS SR algorithm, to recover fine details with lesser artifacts in images. The main contribution of this patch-based approach is that the interfering local structure from other phases can be rejected by employing a similar patch adaptive selection strategy. The effectiveness of our approach is demonstrated through experiments on simulated images and real lung 4D-CT datasets. A comparison with previously published SR reconstruction methods highlights the favorable characteristics of the proposed method.

  19. Variations in tumor size and position due to irregular breathing in 4D-CT: A simulation study

    SciTech Connect

    Sarker, Joyatee; Chu, Alan; Mui, Kit; Wolfgang, John A.; Hirsch, Ariel E.; Chen, George T. Y.; Sharp, Gregory C.

    2010-03-15

    Purpose: To estimate the position and volume errors in 4D-CT caused by irregular breathing. Methods: A virtual 4D-CT scanner was designed to reproduce axial mode scans with retrospective resorting. This virtual scanner creates an artificial spherical tumor based on the specifications of the user, and recreates images that might be produced by a 4D-CT scanner using a patient breathing waveform. 155 respiratory waveforms of patients were used to test the variability of 4D-CT scans. Each breathing waveform was normalized and scaled to 1, 2, and 3 cm peak-to-peak motion, and artificial tumors with 2 and 4 cm radius were simulated for each scaled waveform. The center of mass and volume of resorted 4D-CT images were calculated and compared to the expected values of center of mass and volume for the artificial tumor. Intrasubject variability was investigated by running the virtual scanner over different subintervals of each patient's breathing waveform. Results: The average error in the center of mass location of an artificial tumor was less than 2 mm standard deviation for 2 cm motion. The corresponding average error in volume was less than 4%. In the worst-case scenarios, a center of mass error of 1.0 cm standard deviation and volume errors of 30%-60% at inhale were found. Systematic errors were observed in a subset of patients due to irregular breathing, and these errors were more pronounced when the tumor volume is smaller. Conclusions: Irregular breathing during 4D-CT simulation causes systematic errors in volume and center of mass measurements. These errors are small but depend on the tumor size, motion amplitude, and degree of breathing irregularity.

  20. A fully automated non-external marker 4D-CT sorting algorithm using a serial cine scanning protocol

    NASA Astrophysics Data System (ADS)

    Carnes, Greg; Gaede, Stewart; Yu, Edward; Van Dyk, Jake; Battista, Jerry; Lee, Ting-Yim

    2009-04-01

    Current 4D-CT methods require external marker data to retrospectively sort image data and generate CT volumes. In this work we develop an automated 4D-CT sorting algorithm that performs without the aid of data collected from an external respiratory surrogate. The sorting algorithm requires an overlapping cine scan protocol. The overlapping protocol provides a spatial link between couch positions. Beginning with a starting scan position, images from the adjacent scan position (which spatial match the starting scan position) are selected by maximizing the normalized cross correlation (NCC) of the images at the overlapping slice position. The process was continued by 'daisy chaining' all couch positions using the selected images until an entire 3D volume was produced. The algorithm produced 16 phase volumes to complete a 4D-CT dataset. Additional 4D-CT datasets were also produced using external marker amplitude and phase angle sorting methods. The image quality of the volumes produced by the different methods was quantified by calculating the mean difference of the sorted overlapping slices from adjacent couch positions. The NCC sorted images showed a significant decrease in the mean difference (p < 0.01) for the five patients.

  1. Efficacy evaluation of retrospectively applying the Varian normal breathing predictive filter for volume definition and artifact reduction in 4D CT lung patients.

    PubMed

    Malone, Ciaran; Rock, Luke; Skourou, Christina

    2014-01-01

    Phase-based sorting of four-dimensional computed tomography (4D CT) datasets is prone to image artifacts due to patient's breathing irregularities that occur during the image acquisition. The purpose of this study is to investigate the effect of the Varian normal breathing predictive filter (NBPF) as a retrospective phase-sorting parameter in 4D CT. Ten 4D CT lung cancer datasets were obtained. The volumes of all tumors present, as well as the total lung volume, were calculated on the maximum intensity projection (MIP) images as well as each individual phase image. The NBPF was varied retrospectively within the available range, and changes in volume and image quality were recorded. The patients' breathing trace was analysed and the magnitude and location of any breathing irregularities were correlated to the behavior of the NBPF. The NBPF was found to have a considerable effect on the quality of the images in MIP and single-phase datasets. When used appropriately, the NBPF is shown to have the ability to account for and correct image artifacts. However, when turned off (0%) or set above a critical level (approximately 40%), it resulted in erroneous volume reconstructions with variations in tumor volume up to 26.6%. Those phases associated with peak inspiration were found to be more susceptible to changes in the NBPF. The NBPF settings selected prior to exporting the breathing trace for patients evaluated using 4D CT directly affect the accuracy of the targeting and volume estimation of lung tumors. Recommendations are made to address potential errors in patient anatomy introduced by breathing irregularities, specifically deep breath or cough irregularities, by implementing the proper settings and use of this tool. PMID:24892327

  2. Spatial correspondence of 4D CT ventilation and SPECT pulmonary perfusion defects in patients with malignant airway stenosis

    NASA Astrophysics Data System (ADS)

    Castillo, Richard; Castillo, Edward; McCurdy, Matthew; Gomez, Daniel R.; Block, Alec M.; Bergsma, Derek; Joy, Sarah; Guerrero, Thomas

    2012-04-01

    To determine the spatial overlap agreement between four-dimensional computed tomography (4D CT) ventilation and single photon emission computed tomography (SPECT) perfusion hypo-functioning pulmonary defect regions in a patient population with malignant airway stenosis. Treatment planning 4D CT images were obtained retrospectively for ten lung cancer patients with radiographically demonstrated airway obstruction due to gross tumor volume. Each patient also received a SPECT perfusion study within one week of the planning 4D CT, and prior to the initiation of treatment. Deformable image registration was used to map corresponding lung tissue elements between the extreme component phase images, from which quantitative three-dimensional (3D) images representing the local pulmonary specific ventilation were constructed. Semi-automated segmentation of the percentile perfusion distribution was performed to identify regional defects distal to the known obstructing lesion. Semi-automated segmentation was similarly performed by multiple observers to delineate corresponding defect regions depicted on 4D CT ventilation. Normalized Dice similarity coefficient (NDSC) indices were determined for each observer between SPECT perfusion and 4D CT ventilation defect regions to assess spatial overlap agreement. Tidal volumes determined from 4D CT ventilation were evaluated versus measurements obtained from lung parenchyma segmentation. Linear regression resulted in a linear fit with slope = 1.01 (R2 = 0.99). Respective values for the average DSC, NDSC1 mm and NDSC2 mm for all cases and multiple observers were 0.78, 0.88 and 0.99, indicating that, on average, spatial overlap agreement between ventilation and perfusion defect regions was comparable to the threshold for agreement within 1-2 mm uncertainty. Corresponding coefficients of variation for all metrics were similarly in the range: 0.10%-19%. This study is the first to quantitatively assess 3D spatial overlap agreement between

  3. TU-F-12A-05: Sensitivity of Textural Features to 3D Vs. 4D FDG-PET/CT Imaging in NSCLC Patients

    SciTech Connect

    Yang, F; Nyflot, M; Bowen, S; Kinahan, P; Sandison, G

    2014-06-15

    Purpose: Neighborhood Gray-level difference matrices (NGLDM) based texture parameters extracted from conventional (3D) 18F-FDG PET scans in patients with NSCLC have been previously shown to associate with response to chemoradiation and poorer patient outcome. However, the change in these parameters when utilizing respiratory-correlated (4D) FDG-PET scans has not yet been characterized for NSCLC. The Objectives: of this study was to assess the extent to which NGLDM-based texture parameters on 4D PET images vary with reference to values derived from 3D scans in NSCLC. Methods: Eight patients with newly diagnosed NSCLC treated with concomitant chemoradiotherapy were included in this study. 4D PET scans were reconstructed with OSEM-IR in 5 respiratory phase-binned images and corresponding CT data of each phase were employed for attenuation correction. NGLDM-based texture features, consisting of coarseness, contrast, busyness, complexity and strength, were evaluated for gross tumor volumes defined on 3D/4D PET scans by radiation oncologists. Variation of the obtained texture parameters over the respiratory cycle were examined with respect to values extracted from 3D scans. Results: Differences between texture parameters derived from 4D scans at different respiratory phases and those extracted from 3D scans ranged from −30% to 13% for coarseness, −12% to 40% for contrast, −5% to 50% for busyness, −7% to 38% for complexity, and −43% to 20% for strength. Furthermore, no evident correlations were observed between respiratory phase and 4D scan texture parameters. Conclusion: Results of the current study showed that NGLDM-based texture parameters varied considerably based on choice of 3D PET and 4D PET reconstruction of NSCLC patient images, indicating that standardized image acquisition and analysis protocols need to be established for clinical studies, especially multicenter clinical trials, intending to validate prognostic values of texture features for NSCLC.

  4. A novel CT-FFR method for the coronary artery based on 4D-CT image analysis and structural and fluid analysis

    NASA Astrophysics Data System (ADS)

    Hirohata, K.; Kano, A.; Goryu, A.; Ooga, J.; Hongo, T.; Higashi, S.; Fujisawa, Y.; Wakai, S.; Arakita, K.; Ikeda, Y.; Kaminaga, S.; Ko, B. S.; Seneviratne, S. K.

    2015-03-01

    Non invasive fractional flow reserve derived from CT coronary angiography (CT-FFR) has to date been typically performed using the principles of fluid analysis in which a lumped parameter coronary vascular bed model is assigned to represent the impedance of the downstream coronary vascular networks absent in the computational domain for each coronary outlet. This approach may have a number of limitations. It may not account for the impact of the myocardial contraction and relaxation during the cardiac cycle, patient-specific boundary conditions for coronary artery outlets and vessel stiffness. We have developed a novel approach based on 4D-CT image tracking (registration) and structural and fluid analysis, to address these issues. In our approach, we analyzed the deformation variation of vessels and the volume variation of vessels, primarily from 70% to 100% of cardiac phase, to better define boundary conditions and stiffness of vessels. We used a statistical estimation method based on a hierarchical Bayes model to integrate 4D-CT measurements and structural and fluid analysis data. Under these analysis conditions, we performed structural and fluid analysis to determine pressure, flow rate and CT-FFR. The consistency of this method has been verified by a comparison of 4D-CTFFR analysis results derived from five clinical 4D-CT datasets with invasive measurements of FFR. Additionally, phantom experiments of flexible tubes with/without stenosis using pulsating pumps, flow sensors and pressure sensors were performed. Our results show that the proposed 4D-CT-FFR analysis method has the potential to accurately estimate the effect of coronary artery stenosis on blood flow.

  5. SU-D-207-04: GPU-Based 4D Cone-Beam CT Reconstruction Using Adaptive Meshing Method

    SciTech Connect

    Zhong, Z; Gu, X; Iyengar, P; Mao, W; Wang, J; Guo, X

    2015-06-15

    Purpose: Due to the limited number of projections at each phase, the image quality of a four-dimensional cone-beam CT (4D-CBCT) is often degraded, which decreases the accuracy of subsequent motion modeling. One of the promising methods is the simultaneous motion estimation and image reconstruction (SMEIR) approach. The objective of this work is to enhance the computational speed of the SMEIR algorithm using adaptive feature-based tetrahedral meshing and GPU-based parallelization. Methods: The first step is to generate the tetrahedral mesh based on the features of a reference phase 4D-CBCT, so that the deformation can be well captured and accurately diffused from the mesh vertices to voxels of the image volume. After the mesh generation, the updated motion model and other phases of 4D-CBCT can be obtained by matching the 4D-CBCT projection images at each phase with the corresponding forward projections of the deformed reference phase of 4D-CBCT. The entire process of this 4D-CBCT reconstruction method is implemented on GPU, resulting in significantly increasing the computational efficiency due to its tremendous parallel computing ability. Results: A 4D XCAT digital phantom was used to test the proposed mesh-based image reconstruction algorithm. The image Result shows both bone structures and inside of the lung are well-preserved and the tumor position can be well captured. Compared to the previous voxel-based CPU implementation of SMEIR, the proposed method is about 157 times faster for reconstructing a 10 -phase 4D-CBCT with dimension 256×256×150. Conclusion: The GPU-based parallel 4D CBCT reconstruction method uses the feature-based mesh for estimating motion model and demonstrates equivalent image Result with previous voxel-based SMEIR approach, with significantly improved computational speed.

  6. TH-E-17A-04: Geometric Validation of K-Space Self-Gated 4D-MRI Vs. 4D-CT Using A Respiratory Motion Phantom

    SciTech Connect

    Yue, Y; Fan, Z; Yang, W; Pang, J; McKenzie, E; Deng, Z; Tuli, R; Sandler, H; Li, D; Fraass, B

    2014-06-15

    Purpose: 4D-CT is often limited by motion artifacts, low temporal resolution, and poor phase-based target definition. We recently developed a novel k-space self-gated 4D-MRI technique with high spatial and temporal resolution. The goal here is to geometrically validate 4D-MRI using a MRI-CT compatible respiratory motion phantom and comparison to 4D-CT. Methods: 4D-MRI was acquired using 3T spoiled gradient echo-based 3D projection sequences. Respiratory phases were resolved using self-gated k-space lines as the motion surrogate. Images were reconstructed into 10 temporal bins with 1.56×1.56×1.56mm3. A MRI-CT compatible phantom was designed with a 23mm diameter ball target filled with highconcentration gadolinium(Gd) gel embedded in a 35×40×63mm3 plastic box stabilized with low-concentration Gd gel. The whole phantom was driven by an air pump. Human respiratory motion was mimicked using the controller from a commercial dynamic phantom (RSD). Four breathing settings (rates/depths: 10s/20mm, 6s/15mm, 4s/10mm, 3s/7mm) were scanned with 4D-MRI and 4D-CT (slice thickness 1.25mm). Motion ground-truth was obtained from input signals and real-time video recordings. Reconstructed images were imported into Eclipse(Varian) for target contouring. Volumes and target positions were compared with ground-truth. Initial human study was investigated on a liver patient. Results: 4D-MRI and 4D-CT scans for the different breathing cycles were reconstructed with 10 phases. Target volume in each phase was measured for both 4D-CT and 4D-MRI. Volume percentage difference for the 6.37ml target ranged from 6.67±5.33 to 11.63±5.57 for 4D-CT and from 1.47±0.52 to 2.12±1.60 for 4D-MRI. The Mann-Whitney U-test shows the 4D-MRI is significantly superior to 4D-CT (p=0.021) for phase-based target definition. Centroid motion error ranges were 1.35–1.25mm (4D-CT), and 0.31–0.12mm (4D-MRI). Conclusion: The k-space self-gated 4D-MRI we recently developed can accurately determine phase

  7. TH-E-17A-01: Internal Respiratory Surrogate for 4D CT Using Fourier Transform and Anatomical Features

    SciTech Connect

    Hui, C; Suh, Y; Robertson, D; Pan, T; Das, P; Crane, C; Beddar, S

    2014-06-15

    Purpose: To develop a novel algorithm to generate internal respiratory signals for sorting of four-dimensional (4D) computed tomography (CT) images. Methods: The proposed algorithm extracted multiple time resolved features as potential respiratory signals. These features were taken from the 4D CT images and its Fourier transformed space. Several low-frequency locations in the Fourier space and selected anatomical features from the images were used as potential respiratory signals. A clustering algorithm was then used to search for the group of appropriate potential respiratory signals. The chosen signals were then normalized and averaged to form the final internal respiratory signal. Performance of the algorithm was tested in 50 4D CT data sets and results were compared with external signals from the real-time position management (RPM) system. Results: In almost all cases, the proposed algorithm generated internal respiratory signals that visibly matched the external respiratory signals from the RPM system. On average, the end inspiration times calculated by the proposed algorithm were within 0.1 s of those given by the RPM system. Less than 3% of the calculated end inspiration times were more than one time frame away from those given by the RPM system. In 3 out of the 50 cases, the proposed algorithm generated internal respiratory signals that were significantly smoother than the RPM signals. In these cases, images sorted using the internal respiratory signals showed fewer artifacts in locations corresponding to the discrepancy in the internal and external respiratory signals. Conclusion: We developed a robust algorithm that generates internal respiratory signals from 4D CT images. In some cases, it even showed the potential to outperform the RPM system. The proposed algorithm is completely automatic and generally takes less than 2 min to process. It can be easily implemented into the clinic and can potentially replace the use of external surrogates.

  8. On the automated definition of mobile target volumes from 4D-CT images for stereotactic body radiotherapy

    SciTech Connect

    Zhang Tiezhi; Orton, Nigel P.; Tome, Wolfgang A.

    2005-11-15

    Stereotactic body radiotherapy (SBRT) can be used to treat small lesions in the chest. A vacuum-based immobilization system is used in our clinic for SBRT, and a motion envelope is used in treatment planning. The purpose of this study is to automatically derive motion envelopes using deformable image registration of 4D-CT images, and to assess the effect of abdominal pressure on the motion envelopes. 4D-CT scans at ten phases were acquired prior to treatment for both free and restricted breathing using a vacuum-based immobilization system that includes an abdominal pressure pillow. To study the stability of the motion envelope over the course of treatment, a mid-treatment 4D-CT scan was obtained after delivery of the third fraction for two patients. The planning target volume excluding breathing motion (PTV{sub ex}) was defined on the image set at full exhalation phase and transformed into all other phases using displacement maps from deformable image registration. The motion envelope was obtained as the union of PTV{sub ex} masks of all phases. The ratios of the motion envelope to PTV{sub ex} volume ranged from 1.3 to 2.5. When pressure was applied, the ratios were reduced by as much as 29% compared to free breathing for some patients, but increased by up to 9% for others. The abdominal pressure pillow has more motion restriction effects on the anterior/inferior region of the lung. For one of the two patients for whom the 4D-CT scan was repeated at mid-treatment, the motion envelope was reproducible. However, for the other patient the tumor location and lung motion pattern significantly changed due to changes in the anatomy surrounding the tumor during the course of treatment, indicating that an image-guided approach to SBRT may increase the efficacy of this treatment.

  9. Effects of quantum noise in 4D-CT on deformable image registration and derived ventilation data

    NASA Astrophysics Data System (ADS)

    Latifi, Kujtim; Huang, Tzung-Chi; Feygelman, Vladimir; Budzevich, Mikalai M.; Moros, Eduardo G.; Dilling, Thomas J.; Stevens, Craig W.; van Elmpt, Wouter; Dekker, Andre; Zhang, Geoffrey G.

    2013-11-01

    Quantum noise is common in CT images and is a persistent problem in accurate ventilation imaging using 4D-CT and deformable image registration (DIR). This study focuses on the effects of noise in 4D-CT on DIR and thereby derived ventilation data. A total of six sets of 4D-CT data with landmarks delineated in different phases, called point-validated pixel-based breathing thorax models (POPI), were used in this study. The DIR algorithms, including diffeomorphic morphons (DM), diffeomorphic demons (DD), optical flow and B-spline, were used to register the inspiration phase to the expiration phase. The DIR deformation matrices (DIRDM) were used to map the landmarks. Target registration errors (TRE) were calculated as the distance errors between the delineated and the mapped landmarks. Noise of Gaussian distribution with different standard deviations (SD), from 0 to 200 Hounsfield Units (HU) in amplitude, was added to the POPI models to simulate different levels of quantum noise. Ventilation data were calculated using the ΔV algorithm which calculates the volume change geometrically based on the DIRDM. The ventilation images with different added noise levels were compared using Dice similarity coefficient (DSC). The root mean square (RMS) values of the landmark TRE over the six POPI models for the four DIR algorithms were stable when the noise level was low (SD <150 HU) and increased with added noise when the level is higher. The most accurate DIR was DD with a mean RMS of 1.5 ± 0.5 mm with no added noise and 1.8 ± 0.5 mm with noise (SD = 200 HU). The DSC values between the ventilation images with and without added noise decreased with the noise level, even when the noise level was relatively low. The DIR algorithm most robust with respect to noise was DM, with mean DSC = 0.89 ± 0.01 and 0.66 ± 0.02 for the top 50% ventilation volumes, as compared between 0 added noise and SD = 30 and 200 HU, respectively. Although the landmark TRE were stable with low noise, the

  10. Evaluation of the ΔV 4D CT ventilation calculation method using in vivo xenon CT ventilation data and comparison to other methods.

    PubMed

    Zhang, Geoffrey G; Latifi, Kujtim; Du, Kaifang; Reinhardt, Joseph M; Christensen, Gary E; Ding, Kai; Feygelman, Vladimir; Moros, Eduardo G

    2016-01-01

    Ventilation distribution calculation using 4D CT has shown promising potential in several clinical applications. This study evaluated the direct geometric ventilation calculation method, namely the ΔV method, with xenon-enhanced CT (XeCT) ventilation data from four sheep, and compared it with two other published meth-ods, the Jacobian and the Hounsfield unit (HU) methods. Spearman correlation coefficient (SCC) and Dice similarity coefficient (DSC) were used for the evaluation and comparison. The average SCC with one standard deviation was 0.44 ± 0.13 with a range between 0.29 and 0.61 between the XeCT and ΔV ventilation distributions. The average DSC value for lower 30% ventilation volumes between the XeCT and ΔV ventilation distributions was 0.55 ± 0.07 with a range between 0.48 and 0.63. Ventilation difference introduced by deformable image registration errors improved with smoothing. In conclusion, ventilation distributions generated using ΔV-4D CT and deformable image registration are in reasonably agreement with the in vivo XeCT measured ventilation distribution. PMID:27074479

  11. Comparison of two respiration monitoring systems for 4D imaging with a Siemens CT using a new dynamic breathing phantom

    NASA Astrophysics Data System (ADS)

    Vásquez, A. C.; Runz, A.; Echner, G.; Sroka-Perez, G.; Karger, C. P.

    2012-05-01

    Four-dimensional computed tomography (4D-CT) requires breathing information from the patient, and for this, several systems are available. Testing of these systems, under realistic conditions, requires a phantom with a moving target and an expandable outer contour. An anthropomorphic phantom was developed to simulate patient breathing as well as lung tumor motion. Using the phantom, an optical camera system (GateCT) and a pressure sensor (AZ-733V) were simultaneously operated, and 4D-CTs were reconstructed with a Siemens CT using the provided local-amplitude-based sorting algorithm. The comparison of the tumor trajectories of both systems revealed discrepancies up to 9.7 mm. Breathing signal differences, such as baseline drift, temporal resolution and noise level were shown not to be the reason for this. Instead, the variability of the sampling interval and the accuracy of the sampling rate value written on the header of the GateCT-signal file were identified as the cause. Interpolation to regular sampling intervals and correction of the sampling rate to the actual value removed the observed discrepancies. Consistently, the introduction of sampling interval variability and inaccurate sampling rate values into the header of the AZ-733V file distorted the tumor trajectory for this system. These results underline the importance of testing new equipment thoroughly, especially if components of different manufacturers are combined.

  12. Estimation of Radiation Exposure of 128-Slice 4D-Perfusion CT for the Assessment of Tumor Vascularity

    PubMed Central

    Horger, Marius; Buchgeister, Markus; Fenchel, Michael; Thomas, Christoph; Boehringer, Nadine; Schulze, Maximilian; Tsiflikas, Ilias; Claussen, Claus D.; Heuschmid, Martin

    2010-01-01

    Objective We aimed to estimate the effective dose of 4D-Perfusion-CT protocols of the lung, liver, and pelvis for the assessment of tumor vascularity. Materials and Methods An Alderson-Rando phantom equipped with thermoluminescent dosimeters was used to determine the effective dose values of 4D-Perfusion-CT. Phantom measurements were performed on a 128-slice single-source scanner in adaptive 4D-spiral-mode with bidirectional table movement and a total scan range of 69 mm over a time period of nearly 120 seconds (26 scans). Perfusion measurements were simulated for the lung, liver, and pelvis under the following conditions: lung (80 kV, 60 mAs), liver (80 kV/80 mAs and 80 kV/120 mAs), pelvis (100 kV/80 mAs and 100 kV/120 mAs). Results Depending on gender, the evaluated body region and scan protocol, an effective whole-body dose between 2.9-12.2 mSv, was determined. The radiation exposure administered to gender-specific organs like the female breast tissue (lung perfusion) or to the ovaries (pelvic perfusion) led to an increase in the female specific dose by 86% and 100% in perfusion scans of the lung and the pelvis, respectively. Conclusion Due to a significant radiation dose of 4D-perfusion-CT protocols, the responsible use of this new promising technique is mandatory. Gender- and organ-specific differences should be considered for indication and planning of tumor perfusion scans. PMID:20808699

  13. SU-E-J-154: Image Quality Assessment of Contrast-Enhanced 4D-CT for Pancreatic Adenocarcinoma in Radiotherapy Simulation

    SciTech Connect

    Choi, W; Xue, M; Patel, K; Regine, W; Wang, J; D’Souza, W; Lu, W; Kang, M; Klahr, P

    2015-06-15

    Purpose: This study presents quantitative and qualitative assessment of the image qualities in contrast-enhanced (CE) 3D-CT, 4D-CT and CE 4D-CT to identify feasibility for replacing the clinical standard simulation with a single CE 4D-CT for pancreatic adenocarcinoma (PDA) in radiotherapy simulation. Methods: Ten PDA patients were enrolled and underwent three CT scans: a clinical standard pair of CE 3D-CT immediately followed by a 4D-CT, and a CE 4D-CT one week later. Physicians qualitatively evaluated the general image quality and regional vessel definitions and gave a score from 1 to 5. Next, physicians delineated the contours of the tumor (T) and the normal pancreatic parenchyma (P) on the three CTs (CE 3D-CT, 50% phase for 4D-CT and CE 4D-CT), then high density areas were automatically removed by thresholding at 500 HU and morphological operations. The pancreatic tumor contrast-to-noise ratio (CNR), signal-tonoise ratio (SNR) and conspicuity (C, absolute difference of mean enhancement levels in P and T) were computed to quantitatively assess image quality. The Wilcoxon rank sum test was used to compare these quantities. Results: In qualitative evaluations, CE 3D-CT and CE 4D-CT scored equivalently (4.4±0.4 and 4.3±0.4) and both were significantly better than 4D-CT (3.1±0.6). In quantitative evaluations, the C values were higher in CE 4D-CT (28±19 HU, p=0.19 and 0.17) than the clinical standard pair of CE 3D-CT and 4D-CT (17±12 and 16±17 HU, p=0.65). In CE 3D-CT and CE 4D-CT, mean CNR (1.8±1.4 and 1.8±1.7, p=0.94) and mean SNR (5.8±2.6 and 5.5±3.2, p=0.71) both were higher than 4D-CT (CNR: 1.1±1.3, p<0.3; SNR: 3.3±2.1, p<0.1). The absolute enhancement levels for T and P were higher in CE 4D-CT (87, 82 HU) than in CE 3D-CT (60, 56) and 4DCT (53, 70). Conclusions: The individually optimized CE 4D-CT is feasible and achieved comparable image qualities to the clinical standard simulation. This study was supported in part by Philips Healthcare.

  14. Assessing Cardiac Injury in Mice With Dual Energy-MicroCT, 4D-MicroCT, and MicroSPECT Imaging After Partial Heart Irradiation

    SciTech Connect

    Lee, Chang-Lung; Min, Hooney; Befera, Nicholas; Clark, Darin; Qi, Yi; Das, Shiva; Johnson, G. Allan; Badea, Cristian T.; Kirsch, David G.

    2014-03-01

    Purpose: To develop a mouse model of cardiac injury after partial heart irradiation (PHI) and to test whether dual energy (DE)-microCT and 4-dimensional (4D)-microCT can be used to assess cardiac injury after PHI to complement myocardial perfusion imaging using micro-single photon emission computed tomography (SPECT). Methods and Materials: To study cardiac injury from tangent field irradiation in mice, we used a small-field biological irradiator to deliver a single dose of 12 Gy x-rays to approximately one-third of the left ventricle (LV) of Tie2Cre; p53{sup FL/+} and Tie2Cre; p53{sup FL/−} mice, where 1 or both alleles of p53 are deleted in endothelial cells. Four and 8 weeks after irradiation, mice were injected with gold and iodinated nanoparticle-based contrast agents, and imaged with DE-microCT and 4D-microCT to evaluate myocardial vascular permeability and cardiac function, respectively. Additionally, the same mice were imaged with microSPECT to assess myocardial perfusion. Results: After PHI with tangent fields, DE-microCT scans showed a time-dependent increase in accumulation of gold nanoparticles (AuNp) in the myocardium of Tie2Cre; p53{sup FL/−} mice. In Tie2Cre; p53{sup FL/−} mice, extravasation of AuNp was observed within the irradiated LV, whereas in the myocardium of Tie2Cre; p53{sup FL/+} mice, AuNp were restricted to blood vessels. In addition, data from DE-microCT and microSPECT showed a linear correlation (R{sup 2} = 0.97) between the fraction of the LV that accumulated AuNp and the fraction of LV with a perfusion defect. Furthermore, 4D-microCT scans demonstrated that PHI caused a markedly decreased ejection fraction, and higher end-diastolic and end-systolic volumes, to develop in Tie2Cre; p53{sup FL/−} mice, which were associated with compensatory cardiac hypertrophy of the heart that was not irradiated. Conclusions: Our results show that DE-microCT and 4D-microCT with nanoparticle-based contrast agents are novel imaging approaches

  15. 4D medical image computing and visualization of lung tumor mobility in spatio-temporal CT image data.

    PubMed

    Handels, Heinz; Werner, René; Schmidt, Rainer; Frenzel, Thorsten; Lu, Wei; Low, Daniel; Ehrhardt, Jan

    2007-12-01

    The development of 4D CT imaging has introduced the possibility of measuring breathing motion of tumors and inner organs. Conformal thoracic radiation therapy relies on a quantitative understanding of the position of lungs, lung tumors, and other organs during radiation delivery. Using 4D CT data sets, medical image computing and visualization methods were developed to visualize different aspects of lung and lung tumor mobility during the breathing cycle and to extract quantitative motion parameters. A non-linear registration method was applied to estimate the three-dimensional motion field and to compute 3D point trajectories. Specific visualization techniques were used to display the resulting motion field, the tumor's appearance probabilities during a breathing cycle as well as the volume covered by the moving tumor. Furthermore, trajectories of the tumor center-of-mass and organ specific landmarks were computed for the quantitative analysis of tumor and organ motion. The analysis of 4D data sets of seven patients showed that tumor mobility differs significantly between the patients depending on the individual breathing pattern and tumor location. PMID:17602865

  16. The development of a population of 4D pediatric XCAT phantoms for CT imaging research and optimization

    NASA Astrophysics Data System (ADS)

    Norris, Hannah; Zhang, Yakun; Frush, Jack; Sturgeon, Gregory M.; Minhas, Anum; Tward, Daniel J.; Ratnanather, J. Tilak; Miller, M. I.; Frush, Donald; Samei, Ehsan; Segars, W. Paul

    2014-03-01

    With the increased use of CT examinations, the associated radiation dose has become a large concern, especially for pediatrics. Much research has focused on reducing radiation dose through new scanning and reconstruction methods. Computational phantoms provide an effective and efficient means for evaluating image quality, patient-specific dose, and organ-specific dose in CT. We previously developed a set of highly-detailed 4D reference pediatric XCAT phantoms at ages of newborn, 1, 5, 10, and 15 years with organ and tissues masses matched to ICRP Publication 89 values. We now extend this reference set to a series of 64 pediatric phantoms of a variety of ages and height and weight percentiles, representative of the public at large. High resolution PET-CT data was reviewed by a practicing experienced radiologist for anatomic regularity and was then segmented with manual and semi-automatic methods to form a target model. A Multi-Channel Large Deformation Diffeomorphic Metric Mapping (MC-LDDMM) algorithm was used to calculate the transform from the best age matching pediatric reference phantom to the patient target. The transform was used to complete the target, filling in the non-segmented structures and defining models for the cardiac and respiratory motions. The complete phantoms, consisting of thousands of structures, were then manually inspected for anatomical accuracy. 3D CT data was simulated from the phantoms to demonstrate their ability to generate realistic, patient quality imaging data. The population of pediatric phantoms developed in this work provides a vital tool to investigate dose reduction techniques in 3D and 4D pediatric CT.

  17. Iterative 4D cardiac micro-CT image reconstruction using an adaptive spatio-temporal sparsity prior

    NASA Astrophysics Data System (ADS)

    Ritschl, Ludwig; Sawall, Stefan; Knaup, Michael; Hess, Andreas; Kachelrieß, Marc

    2012-03-01

    Temporal-correlated image reconstruction, also known as 4D CT image reconstruction, is a big challenge in computed tomography. The reasons for incorporating the temporal domain into the reconstruction are motions of the scanned object, which would otherwise lead to motion artifacts. The standard method for 4D CT image reconstruction is extracting single motion phases and reconstructing them separately. These reconstructions can suffer from undersampling artifacts due to the low number of used projections in each phase. There are different iterative methods which try to incorporate some a priori knowledge to compensate for these artifacts. In this paper we want to follow this strategy. The cost function we use is a higher dimensional cost function which accounts for the sparseness of the measured signal in the spatial and temporal directions. This leads to the definition of a higher dimensional total variation. The method is validated using in vivo cardiac micro-CT mouse data. Additionally, we compare the results to phase-correlated reconstructions using the FDK algorithm and a total variation constrained reconstruction, where the total variation term is only defined in the spatial domain. The reconstructed datasets show strong improvements in terms of artifact reduction and low-contrast resolution compared to other methods. Thereby the temporal resolution of the reconstructed signal is not affected.

  18. SU-D-17A-03: 5D Respiratory Motion Model Based Iterative Reconstruction Method for 4D Cone-Beam CT

    SciTech Connect

    Gao, Y; Thomas, D; Low, D; Gao, H

    2014-06-01

    Purpose: The purpose of this work is to develop a new iterative reconstruction method for 4D cone-beam CT (CBCT) based on a published time-independent 5D respiratory motion model. The proposed method will offer a single high-resolution image at a user-selected breathing phase and the 5D motion model parameters, which could be used to generate the breathing pattern during the CT acquisition. Methods: 5D respiratory motion model was proposed for accurately modeling the motion of lung and lung tumor tissues. 4D images are then parameterized by a reference image, measured breathing amplitude, breathing rate, two time-independent vector fields that describe the 5D model parameters, and a scalar field that describes the change in HU as a function of breathing amplitude. In contrast with the traditional method of reconstructing multiple temporal image phases to reduce respiratory artifact, 5D model based method simplify the problem into the reconstruction of a single reference image and the 5D motion model parameters. The reconstruction formulation of the reference image and scalar and vector fields is a nonlinear least-square optimization problem that consists of solving the reference image and fields alternately, in which the reference image is regularized with the total variation sparsity transform and the vector fields are solved through linearizations regularized by the H1 norm. 2D lung simulations were performed in this proof-of-concept study. Results: The breathing amplitude, its rate, and the corresponding scalar and vector fields were generated from a patient case. Compared with filtered backprojection method and sparsity regularized iterative method for the phase-by-phase reconstruction, the proposed 5D motion model based method yielded improved image quality. Conclusion: Based on 5D respiratory motion model, we have developed a new iterative reconstruction method for 4D CBCT that has the potential for improving image quality while providing needed on

  19. 4D motion modeling of the coronary arteries from CT images for robotic assisted minimally invasive surgery

    NASA Astrophysics Data System (ADS)

    Zhang, Dong Ping; Edwards, Eddie; Mei, Lin; Rueckert, Daniel

    2009-02-01

    In this paper, we present a novel approach for coronary artery motion modeling from cardiac Computed Tomography( CT) images. The aim of this work is to develop a 4D motion model of the coronaries for image guidance in robotic-assisted totally endoscopic coronary artery bypass (TECAB) surgery. To utilize the pre-operative cardiac images to guide the minimally invasive surgery, it is essential to have a 4D cardiac motion model to be registered with the stereo endoscopic images acquired intraoperatively using the da Vinci robotic system. In this paper, we are investigating the extraction of the coronary arteries and the modelling of their motion from a dynamic sequence of cardiac CT. We use a multi-scale vesselness filter to enhance vessels in the cardiac CT images. The centerlines of the arteries are extracted using a ridge traversal algorithm. Using this method the coronaries can be extracted in near real-time as only local information is used in vessel tracking. To compute the deformation of the coronaries due to cardiac motion, the motion is extracted from a dynamic sequence of cardiac CT. Each timeframe in this sequence is registered to the end-diastole timeframe of the sequence using a non-rigid registration algorithm based on free-form deformations. Once the images have been registered a dynamic motion model of the coronaries can be obtained by applying the computed free-form deformations to the extracted coronary arteries. To validate the accuracy of the motion model we compare the actual position of the coronaries in each time frame with the predicted position of the coronaries as estimated from the non-rigid registration. We expect that this motion model of coronaries can facilitate the planning of TECAB surgery, and through the registration with real-time endoscopic video images it can reduce the conversion rate from TECAB to conventional procedures.

  20. Image quality in thoracic 4D cone-beam CT: A sensitivity analysis of respiratory signal, binning method, reconstruction algorithm, and projection angular spacing

    PubMed Central

    Shieh, Chun-Chien; Kipritidis, John; O’Brien, Ricky T.; Kuncic, Zdenka; Keall, Paul J.

    2014-01-01

    Purpose: Respiratory signal, binning method, and reconstruction algorithm are three major controllable factors affecting image quality in thoracic 4D cone-beam CT (4D-CBCT), which is widely used in image guided radiotherapy (IGRT). Previous studies have investigated each of these factors individually, but no integrated sensitivity analysis has been performed. In addition, projection angular spacing is also a key factor in reconstruction, but how it affects image quality is not obvious. An investigation of the impacts of these four factors on image quality can help determine the most effective strategy in improving 4D-CBCT for IGRT. Methods: Fourteen 4D-CBCT patient projection datasets with various respiratory motion features were reconstructed with the following controllable factors: (i) respiratory signal (real-time position management, projection image intensity analysis, or fiducial marker tracking), (ii) binning method (phase, displacement, or equal-projection-density displacement binning), and (iii) reconstruction algorithm [Feldkamp–Davis–Kress (FDK), McKinnon–Bates (MKB), or adaptive-steepest-descent projection-onto-convex-sets (ASD-POCS)]. The image quality was quantified using signal-to-noise ratio (SNR), contrast-to-noise ratio, and edge-response width in order to assess noise/streaking and blur. The SNR values were also analyzed with respect to the maximum, mean, and root-mean-squared-error (RMSE) projection angular spacing to investigate how projection angular spacing affects image quality. Results: The choice of respiratory signals was found to have no significant impact on image quality. Displacement-based binning was found to be less prone to motion artifacts compared to phase binning in more than half of the cases, but was shown to suffer from large interbin image quality variation and large projection angular gaps. Both MKB and ASD-POCS resulted in noticeably improved image quality almost 100% of the time relative to FDK. In addition, SNR

  1. Image quality in thoracic 4D cone-beam CT: A sensitivity analysis of respiratory signal, binning method, reconstruction algorithm, and projection angular spacing

    SciTech Connect

    Shieh, Chun-Chien; Kipritidis, John; O’Brien, Ricky T.; Keall, Paul J.; Kuncic, Zdenka

    2014-04-15

    Purpose: Respiratory signal, binning method, and reconstruction algorithm are three major controllable factors affecting image quality in thoracic 4D cone-beam CT (4D-CBCT), which is widely used in image guided radiotherapy (IGRT). Previous studies have investigated each of these factors individually, but no integrated sensitivity analysis has been performed. In addition, projection angular spacing is also a key factor in reconstruction, but how it affects image quality is not obvious. An investigation of the impacts of these four factors on image quality can help determine the most effective strategy in improving 4D-CBCT for IGRT. Methods: Fourteen 4D-CBCT patient projection datasets with various respiratory motion features were reconstructed with the following controllable factors: (i) respiratory signal (real-time position management, projection image intensity analysis, or fiducial marker tracking), (ii) binning method (phase, displacement, or equal-projection-density displacement binning), and (iii) reconstruction algorithm [Feldkamp–Davis–Kress (FDK), McKinnon–Bates (MKB), or adaptive-steepest-descent projection-onto-convex-sets (ASD-POCS)]. The image quality was quantified using signal-to-noise ratio (SNR), contrast-to-noise ratio, and edge-response width in order to assess noise/streaking and blur. The SNR values were also analyzed with respect to the maximum, mean, and root-mean-squared-error (RMSE) projection angular spacing to investigate how projection angular spacing affects image quality. Results: The choice of respiratory signals was found to have no significant impact on image quality. Displacement-based binning was found to be less prone to motion artifacts compared to phase binning in more than half of the cases, but was shown to suffer from large interbin image quality variation and large projection angular gaps. Both MKB and ASD-POCS resulted in noticeably improved image quality almost 100% of the time relative to FDK. In addition, SNR

  2. IMRT treatment plans and functional planning with functional lung imaging from 4D-CT for thoracic cancer patients

    PubMed Central

    2013-01-01

    Background and purpose Currently, the inhomogeneity of the pulmonary function is not considered when treatment plans are generated in thoracic cancer radiotherapy. This study evaluates the dose of treatment plans on highly-functional volumes and performs functional treatment planning by incorporation of ventilation data from 4D-CT. Materials and methods Eleven patients were included in this retrospective study. Ventilation was calculated using 4D-CT. Two treatment plans were generated for each case, the first one without the incorporation of the ventilation and the second with it. The dose of the first plans was overlapped with the ventilation and analyzed. Highly-functional regions were avoided in the second treatment plans. Results For small targets in the first plans (PTV < 400 cc, 6 cases), all V5, V20 and the mean lung dose values for the highly-functional regions were lower than that of the total lung. For large targets, two out of five cases had higher V5 and V20 values for the highly-functional regions. All the second plans were within constraints. Conclusion Radiation treatments affect functional lung more seriously in large tumor cases. With compromise of dose to other critical organs, functional treatment planning to reduce dose in highly-functional lung volumes can be achieved PMID:23281734

  3. TH-E-BRF-02: 4D-CT Ventilation Image-Based IMRT Plans Are Dosimetrically Comparable to SPECT Ventilation Image-Based Plans

    SciTech Connect

    Kida, S; Bal, M; Kabus, S; Loo, B; Keall, P; Yamamoto, T

    2014-06-15

    Purpose: An emerging lung ventilation imaging method based on 4D-CT can be used in radiotherapy to selectively avoid irradiating highly-functional lung regions, which may reduce pulmonary toxicity. Efforts to validate 4DCT ventilation imaging have been focused on comparison with other imaging modalities including SPECT and xenon CT. The purpose of this study was to compare 4D-CT ventilation image-based functional IMRT plans with SPECT ventilation image-based plans as reference. Methods: 4D-CT and SPECT ventilation scans were acquired for five thoracic cancer patients in an IRB-approved prospective clinical trial. The ventilation images were created by quantitative analysis of regional volume changes (a surrogate for ventilation) using deformable image registration of the 4D-CT images. A pair of 4D-CT ventilation and SPECT ventilation image-based IMRT plans was created for each patient. Regional ventilation information was incorporated into lung dose-volume objectives for IMRT optimization by assigning different weights on a voxel-by-voxel basis. The objectives and constraints of the other structures in the plan were kept identical. The differences in the dose-volume metrics have been evaluated and tested by a paired t-test. SPECT ventilation was used to calculate the lung functional dose-volume metrics (i.e., mean dose, V20 and effective dose) for both 4D-CT ventilation image-based and SPECT ventilation image-based plans. Results: Overall there were no statistically significant differences in any dose-volume metrics between the 4D-CT and SPECT ventilation imagebased plans. For example, the average functional mean lung dose of the 4D-CT plans was 26.1±9.15 (Gy), which was comparable to 25.2±8.60 (Gy) of the SPECT plans (p = 0.89). For other critical organs and PTV, nonsignificant differences were found as well. Conclusion: This study has demonstrated that 4D-CT ventilation image-based functional IMRT plans are dosimetrically comparable to SPECT ventilation image

  4. Computational biomechanics and experimental validation of vessel deformation based on 4D-CT imaging of the porcine aorta

    NASA Astrophysics Data System (ADS)

    Hazer, Dilana; Finol, Ender A.; Kostrzewa, Michael; Kopaigorenko, Maria; Richter, Götz-M.; Dillmann, Rüdiger

    2009-02-01

    Cardiovascular disease results from pathological biomechanical conditions and fatigue of the vessel wall. Image-based computational modeling provides a physical and realistic insight into the patient-specific biomechanics and enables accurate predictive simulations of development, growth and failure of cardiovascular disease. An experimental validation is necessary for the evaluation and the clinical implementation of such computational models. In the present study, we have implemented dynamic Computed-Tomography (4D-CT) imaging and catheter-based in vivo measured pressures to numerically simulate and experimentally evaluate the biomechanics of the porcine aorta. The computations are based on the Finite Element Method (FEM) and simulate the arterial wall response to the transient pressure-based boundary condition. They are evaluated by comparing the numerically predicted wall deformation and that calculated from the acquired 4D-CT data. The dynamic motion of the vessel is quantified by means of the hydraulic diameter, analyzing sequences at 5% increments over the cardiac cycle. Our results show that accurate biomechanical modeling is possible using FEM-based simulations. The RMS error of the computed hydraulic diameter at five cross-sections of the aorta was 0.188, 0.252, 0.280, 0.237 and 0.204 mm, which is equivalent to 1.7%, 2.3%, 2.7%, 2.3% and 2.0%, respectively, when expressed as a function of the time-averaged hydraulic diameter measured from the CT images. The present investigation is a first attempt to simulate and validate vessel deformation based on realistic morphological data and boundary conditions. An experimentally validated system would help in evaluating individual therapies and optimal treatment strategies in the field of minimally invasive endovascular surgery.

  5. Dynamic Multiscale Boundary Conditions for 4D CT Images of Healthy and Emphysematous Rat

    SciTech Connect

    Jacob, Rick E.; Carson, James P.; Thomas, Mathew; Einstein, Daniel R.

    2013-06-14

    Changes in the shape of the lung during breathing determine the movement of airways and alveoli, and thus impact airflow dynamics. Modeling airflow dynamics in health and disease is a key goal for predictive multiscale models of respiration. Past efforts to model changes in lung shape during breathing have measured shape at multiple breath-holds. However, breath-holds do not capture hysteretic differences between inspiration and expiration resulting from the additional energy required for inspiration. Alternatively, imaging dynamically – without breath-holds – allows measurement of hysteretic differences. In this study, we acquire multiple micro-CT images per breath (4DCT) in live rats, and from these images we develop, for the first time, dynamic volume maps. These maps show changes in local volume across the entire lung throughout the breathing cycle and accurately predict the global pressure-volume (PV) hysteresis.

  6. 4D cone-beam CT imaging for guidance in radiation therapy: setup verification by use of implanted fiducial markers

    NASA Astrophysics Data System (ADS)

    Jin, Peng; van Wieringen, Niek; Hulshof, Maarten C. C. M.; Bel, Arjan; Alderliesten, Tanja

    2016-03-01

    The use of 4D cone-beam computed tomography (CBCT) and fiducial markers for guidance during radiation therapy of mobile tumors is challenging due to the trade-off between image quality, imaging dose, and scanning time. We aimed to investigate the visibility of markers and the feasibility of marker-based 4D registration and manual respiration-induced marker motion quantification for different CBCT acquisition settings. A dynamic thorax phantom and a patient with implanted gold markers were included. For both the phantom and patient, the peak-to-peak amplitude of marker motion in the cranial-caudal direction ranged from 5.3 to 14.0 mm, which did not affect the marker visibility and the associated marker-based registration feasibility. While using a medium field of view (FOV) and the same total imaging dose as is applied for 3D CBCT scanning in our clinic, it was feasible to attain an improved marker visibility by reducing the imaging dose per projection and increasing the number of projection images. For a small FOV with a shorter rotation arc but similar total imaging dose, streak artifacts were reduced due to using a smaller sampling angle. Additionally, the use of a small FOV allowed reducing total imaging dose and scanning time (~2.5 min) without losing the marker visibility. In conclusion, by using 4D CBCT with identical or lower imaging dose and a reduced gantry speed, it is feasible to attain sufficient marker visibility for marker-based 4D setup verification. Moreover, regardless of the settings, manual marker motion quantification can achieve a high accuracy with the error <1.2 mm.

  7. Respiratory motion variations from skin surface on lung cancer patients from 4D CT data

    NASA Astrophysics Data System (ADS)

    Gallego-Ortiz, Nicolas; Orban de Xivry, Jonathan; Descampe, Antonin; Goossens, Samuel; Geets, Xavier; Janssens, Guillaume; Macq, Benoit

    2014-03-01

    In radiation therapy of thorax and abdomen regions, knowing how respiratory motion modifies tumor position and trajectory is crucial for accurate dose delivery to tumors while avoiding healthy tissue and organs at risk. Three types of variations are studied: motion amplitudes measured from the patient's skin surface and internal tumor trajectory, internal/external correlations and tumor trajectory baseline shift. Four male patients with lung cancer with three repeated 4D computed tomography (4DCT) scans, taken on different treatment days, were studied. Surfaces were extracted from 4DCT scans by segmentation. Motion over specific regions of interest was analyzed with respect to the motion of the tumor center of mass and correlation coefficient was computed. Tumor baseline shifts were analyzed after rigid registration based on vertebrae and surface registration. External amplitude variations were observed between fractions. Correlation coefficients of internal trajectories and external distances are greater than 0.6 in the abdomen. This correlation was observable and significant for all patients showing that the external motion is a good surrogate for internal movement on an intra-fraction basis. However for the inter-fraction case, external amplitude variations were observed between fractions and no correlation was found with the internal amplitude variations. Moreover, baseline shifts after surface registration were greater than those after vertebrae registration and the mean distance between surfaces after registration was not correlated to the magnitude of the baseline shift. These two observations show that, with the current representation of the external surface, inter-fraction variations are not detectable on the surface.

  8. Evaluation of Fractional Regional Ventilation Using 4D-CT and Effects of Breathing Maneuvers on Ventilation

    SciTech Connect

    Mistry, Nilesh N.; Diwanji, Tejan; Shi, Xiutao; Pokharel, Sabin; Feigenberg, Steven; Scharf, Steven M.; D'Souza, Warren D.

    2013-11-15

    Purpose: Current implementations of methods based on Hounsfield units to evaluate regional lung ventilation do not directly incorporate tissue-based mass changes that occur over the respiratory cycle. To overcome this, we developed a 4-dimensional computed tomography (4D-CT)-based technique to evaluate fractional regional ventilation (FRV) that uses an individualized ratio of tidal volume to end-expiratory lung volume for each voxel. We further evaluated the effect of different breathing maneuvers on regional ventilation. The results from this work will help elucidate the relationship between global and regional lung function. Methods and Materials: Eight patients underwent 3 sets of 4D-CT scans during 1 session using free-breathing, audiovisual guidance, and active breathing control. FRV was estimated using a density-based algorithm with mass correction. Internal validation between global and regional ventilation was performed by use of the imaging data collected during the use of active breathing control. The impact of breathing maneuvers on FRV was evaluated comparing the tidal volume from 3 breathing methods. Results: Internal validation through comparison between the global and regional changes in ventilation revealed a strong linear correlation (slope of 1.01, R{sup 2} of 0.97) between the measured global lung volume and the regional lung volume calculated by use of the “mass corrected” FRV. A linear relationship was established between the tidal volume measured with the automated breathing control system and FRV based on 4D-CT imaging. Consistently larger breathing volumes were observed when coached breathing techniques were used. Conclusions: The technique presented improves density-based evaluation of lung ventilation and establishes a link between global and regional lung ventilation volumes. Furthermore, the results obtained are comparable with those of other techniques of functional evaluation such as spirometry and hyperpolarized-gas magnetic

  9. SU-E-J-153: Reconstructing 4D Cone Beam CT Images for Clinical QA of Lung SABR Treatments

    SciTech Connect

    Beaudry, J; Bergman, A; Cropp, R

    2015-06-15

    Purpose: To verify that the planned Primary Target Volume (PTV) and Internal Gross Tumor Volume (IGTV) fully enclose a moving lung tumor volume as visualized on a pre-SABR treatment verification 4D Cone Beam CT. Methods: Daily 3DCBCT image sets were acquired immediately prior to treatment for 10 SABR lung patients using the on-board imaging system integrated into a Varian TrueBeam (v1.6: no 4DCBCT module available). Respiratory information was acquired during the scan using the Varian RPM system. The CBCT projections were sorted into 8 bins offline, both by breathing phase and amplitude, using in-house software. An iterative algorithm based on total variation minimization, implemented in the open source reconstruction toolkit (RTK), was used to reconstruct the binned projections into 4DCBCT images. The relative tumor motion was quantified by tracking the centroid of the tumor volume from each 4DCBCT image. Following CT-CBCT registration, the planning CT volumes were compared to the location of the CBCT tumor volume as it moves along its breathing trajectory. An overlap metric quantified the ability of the planned PTV and IGTV to contain the tumor volume at treatment. Results: The 4DCBCT reconstructed images visibly show the tumor motion. The mean overlap between the planned PTV (IGTV) and the 4DCBCT tumor volumes was 100% (94%), with an uncertainty of 5% from the 4DCBCT tumor volume contours. Examination of the tumor motion and overlap metric verify that the IGTV drawn at the planning stage is a good representation of the tumor location at treatment. Conclusion: It is difficult to compare GTV volumes from a 4DCBCT and a planning CT due to image quality differences. However, it was possible to conclude the GTV remained within the PTV 100% of the time thus giving the treatment staff confidence that SABR lung treatements are being delivered accurately.

  10. Dynamic Multiscale Boundary Conditions for 4D CT of Healthy and Emphysematous Rats

    PubMed Central

    Jacob, Richard E.; Carson, James P.; Thomas, Mathew; Einstein, Daniel R.

    2013-01-01

    Changes in the shape of the lung during breathing determine the movement of airways and alveoli, and thus impact airflow dynamics. Modeling airflow dynamics in health and disease is a key goal for predictive multiscale models of respiration. Past efforts to model changes in lung shape during breathing have measured shape at multiple breath-holds. However, breath-holds do not capture hysteretic differences between inspiration and expiration resulting from the additional energy required for inspiration. Alternatively, imaging dynamically – without breath-holds – allows measurement of hysteretic differences. In this study, we acquire multiple micro-CT images per breath (4DCT) in live rats, and from these images we develop, for the first time, dynamic volume maps. These maps show changes in local volume across the entire lung throughout the breathing cycle and accurately predict the global pressure-volume (PV) hysteresis. Male Sprague-Dawley rats were given either a full- or partial-lung dose of elastase or saline as a control. After three weeks, 4DCT images of the mechanically ventilated rats under anesthesia were acquired dynamically over the breathing cycle (11 time points, ≤100 ms temporal resolution, 8 cmH2O peak pressure). Non-rigid image registration was applied to determine the deformation gradient – a numerical description of changes to lung shape – at each time point. The registration accuracy was evaluated by landmark identification. Of 67 landmarks, one was determined misregistered by all three observers, and 11 were determined misregistered by two observers. Volume change maps were calculated on a voxel-by-voxel basis at all time points using both the Jacobian of the deformation gradient and the inhaled air fraction. The calculated lung PV hysteresis agrees with pressure-volume curves measured by the ventilator. Volume maps in diseased rats show increased compliance and ventilation heterogeneity. Future predictive multiscale models of rodent

  11. Validating and improving CT ventilation imaging by correlating with ventilation 4D-PET/CT using {sup 68}Ga-labeled nanoparticles

    SciTech Connect

    Kipritidis, John Keall, Paul J.; Siva, Shankar; Hofman, Michael S.; Callahan, Jason; Hicks, Rodney J.

    2014-01-15

    Purpose: CT ventilation imaging is a novel functional lung imaging modality based on deformable image registration. The authors present the first validation study of CT ventilation using positron emission tomography with{sup 68}Ga-labeled nanoparticles (PET-Galligas). The authors quantify this agreement for different CT ventilation metrics and PET reconstruction parameters. Methods: PET-Galligas ventilation scans were acquired for 12 lung cancer patients using a four-dimensional (4D) PET/CT scanner. CT ventilation images were then produced by applying B-spline deformable image registration between the respiratory correlated phases of the 4D-CT. The authors test four ventilation metrics, two existing and two modified. The two existing metrics model mechanical ventilation (alveolar air-flow) based on Hounsfield unit (HU) change (V{sub HU}) or Jacobian determinant of deformation (V{sub Jac}). The two modified metrics incorporate a voxel-wise tissue-density scaling (ρV{sub HU} and ρV{sub Jac}) and were hypothesized to better model the physiological ventilation. In order to assess the impact of PET image quality, comparisons were performed using both standard and respiratory-gated PET images with the former exhibiting better signal. Different median filtering kernels (σ{sub m} = 0 or 3 mm) were also applied to all images. As in previous studies, similarity metrics included the Spearman correlation coefficient r within the segmented lung volumes, and Dice coefficient d{sub 20} for the (0 − 20)th functional percentile volumes. Results: The best agreement between CT and PET ventilation was obtained comparing standard PET images to the density-scaled HU metric (ρV{sub HU}) with σ{sub m} = 3 mm. This leads to correlation values in the ranges 0.22 ⩽ r ⩽ 0.76 and 0.38 ⩽ d{sub 20} ⩽ 0.68, with r{sup ¯}=0.42±0.16 and d{sup ¯}{sub 20}=0.52±0.09 averaged over the 12 patients. Compared to Jacobian-based metrics, HU-based metrics lead to statistically significant

  12. Tumor Tracking Method Based on a Deformable 4D CT Breathing Motion Model Driven by an External Surface Surrogate

    SciTech Connect

    Fassi, Aurora; Schaerer, Joël; Fernandes, Mathieu; Riboldi, Marco; Sarrut, David; Baroni, Guido

    2014-01-01

    Purpose: To develop a tumor tracking method based on a surrogate-driven motion model, which provides noninvasive dynamic localization of extracranial targets for the compensation of respiration-induced intrafraction motion in high-precision radiation therapy. Methods and Materials: The proposed approach is based on a patient-specific breathing motion model, derived a priori from 4-dimensional planning computed tomography (CT) images. Model parameters (respiratory baseline, amplitude, and phase) are retrieved and updated at each treatment fraction according to in-room radiography acquisition and optical surface imaging. The baseline parameter is adapted to the interfraction variations obtained from the daily cone beam (CB) CT scan. The respiratory amplitude and phase are extracted from an external breathing surrogate, estimated from the displacement of the patient thoracoabdominal surface, acquired with a noninvasive surface imaging device. The developed method was tested on a database of 7 lung cancer patients, including the synchronized information on internal and external respiratory motion during a CBCT scan. Results: About 30 seconds of simultaneous acquisition of CBCT and optical surface images were analyzed for each patient. The tumor trajectories identified in CBCT projections were used as reference and compared with the target trajectories estimated from surface displacement with the a priori motion model. The resulting absolute differences between the reference and estimated tumor motion along the 2 image dimensions ranged between 0.7 and 2.4 mm; the measured phase shifts did not exceed 7% of the breathing cycle length. Conclusions: We investigated a tumor tracking method that integrates breathing motion information provided by the 4-dimensional planning CT with surface imaging at the time of treatment, representing an alternative approach to point-based external–internal correlation models. Although an in-room radiograph-based assessment of the

  13. TH-E-17A-02: High-Pitch and Sparse-View Helical 4D CT Via Iterative Image Reconstruction Method Based On Tensor Framelet

    SciTech Connect

    Guo, M; Nam, H; Li, R; Xing, L; Gao, H

    2014-06-15

    Purpose: 4D CT is routinely performed during radiation therapy treatment planning of thoracic and abdominal cancers. Compared with the cine mode, the helical mode is advantageous in temporal resolution. However, a low pitch (∼0.1) for 4D CT imaging is often required instead of the standard pitch (∼1) for static imaging, since standard image reconstruction based on analytic method requires the low-pitch scanning in order to satisfy the data sufficient condition when reconstructing each temporal frame individually. In comparison, the flexible iterative method enables the reconstruction of all temporal frames simultaneously, so that the image similarity among frames can be utilized to possibly perform high-pitch and sparse-view helical 4D CT imaging. The purpose of this work is to investigate such an exciting possibility for faster imaging with lower dose. Methods: A key for highpitch and sparse-view helical 4D CT imaging is the simultaneous reconstruction of all temporal frames using the prior that temporal frames are continuous along the temporal direction. In this work, such a prior is regularized through the sparsity transform based on spatiotemporal tensor framelet (TF) as a multilevel and high-order extension of total variation transform. Moreover, GPU-based fast parallel computing of X-ray transform and its adjoint together with split Bregman method is utilized for solving the 4D image reconstruction problem efficiently and accurately. Results: The simulation studies based on 4D NCAT phantoms were performed with various pitches (i.e., 0.1, 0.2, 0.5, and 1) and sparse views (i.e., 400 views per rotation instead of standard >2000 views per rotation), using 3D iterative individual reconstruction method based on 3D TF and 4D iterative simultaneous reconstruction method based on 4D TF respectively. Conclusion: The proposed TF-based simultaneous 4D image reconstruction method enables high-pitch and sparse-view helical 4D CT with lower dose and faster speed.

  14. Estimation of the delivered patient dose in lung IMRT treatment based on deformable registration of 4D-CT data and Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Flampouri, Stella; Jiang, Steve B.; Sharp, Greg C.; Wolfgang, John; Patel, Abhijit A.; Choi, Noah C.

    2006-06-01

    The purpose of this study is to accurately estimate the difference between the planned and the delivered dose due to respiratory motion and free breathing helical CT artefacts for lung IMRT treatments, and to estimate the impact of this difference on clinical outcome. Six patients with representative tumour motion, size and position were selected for this retrospective study. For each patient, we had acquired both a free breathing helical CT and a ten-phase 4D-CT scan. A commercial treatment planning system was used to create four IMRT plans for each patient. The first two plans were based on the GTV as contoured on the free breathing helical CT set, with a GTV to PTV expansion of 1.5 cm and 2.0 cm, respectively. The third plan was based on the ITV, a composite volume formed by the union of the CTV volumes contoured on free breathing helical CT, end-of-inhale (EOI) and end-of-exhale (EOE) 4D-CT. The fourth plan was based on GTV contoured on the EOE 4D-CT. The prescribed dose was 60 Gy for all four plans. Fluence maps and beam setup parameters of the IMRT plans were used by the Monte Carlo dose calculation engine MCSIM for absolute dose calculation on both the free breathing CT and 4D-CT data. CT deformable registration between the breathing phases was performed to estimate the motion trajectory for both the tumour and healthy tissue. Then, a composite dose distribution over the whole breathing cycle was calculated as a final estimate of the delivered dose. EUD values were computed on the basis of the composite dose for all four plans. For the patient with the largest motion effect, the difference in the EUD of CTV between the planed and the delivered doses was 33, 11, 1 and 0 Gy for the first, second, third and fourth plan, respectively. The number of breathing phases required for accurate dose prediction was also investigated. With the advent of 4D-CT, deformable registration and Monte Carlo simulations, it is feasible to perform an accurate calculation of the

  15. Estimation of the delivered patient dose in lung IMRT treatment based on deformable registration of 4D-CT data and Monte Carlo simulations.

    PubMed

    Flampouri, Stella; Jiang, Steve B; Sharp, Greg C; Wolfgang, John; Patel, Abhijit A; Choi, Noah C

    2006-06-01

    The purpose of this study is to accurately estimate the difference between the planned and the delivered dose due to respiratory motion and free breathing helical CT artefacts for lung IMRT treatments, and to estimate the impact of this difference on clinical outcome. Six patients with representative tumour motion, size and position were selected for this retrospective study. For each patient, we had acquired both a free breathing helical CT and a ten-phase 4D-CT scan. A commercial treatment planning system was used to create four IMRT plans for each patient. The first two plans were based on the GTV as contoured on the free breathing helical CT set, with a GTV to PTV expansion of 1.5 cm and 2.0 cm, respectively. The third plan was based on the ITV, a composite volume formed by the union of the CTV volumes contoured on free breathing helical CT, end-of-inhale (EOI) and end-of-exhale (EOE) 4D-CT. The fourth plan was based on GTV contoured on the EOE 4D-CT. The prescribed dose was 60 Gy for all four plans. Fluence maps and beam setup parameters of the IMRT plans were used by the Monte Carlo dose calculation engine MCSIM for absolute dose calculation on both the free breathing CT and 4D-CT data. CT deformable registration between the breathing phases was performed to estimate the motion trajectory for both the tumour and healthy tissue. Then, a composite dose distribution over the whole breathing cycle was calculated as a final estimate of the delivered dose. EUD values were computed on the basis of the composite dose for all four plans. For the patient with the largest motion effect, the difference in the EUD of CTV between the planed and the delivered doses was 33, 11, 1 and 0 Gy for the first, second, third and fourth plan, respectively. The number of breathing phases required for accurate dose prediction was also investigated. With the advent of 4D-CT, deformable registration and Monte Carlo simulations, it is feasible to perform an accurate calculation of the

  16. Simulation of dosimetric consequences of 4D-CT-based motion margin estimation for proton radiotherapy using patient tumor motion data

    NASA Astrophysics Data System (ADS)

    Koybasi, Ozhan; Mishra, Pankaj; St. James, Sara; Lewis, John H.; Seco, Joao

    2014-02-01

    For the radiation treatment of lung cancer patients, four-dimensional computed tomography (4D-CT) is a common practice used clinically to image tumor motion and subsequently determine the internal target volume (ITV) from the maximum intensity projection (MIP) images. ITV, which is derived from short pre-treatment 4D-CT scan (<6 s per couch position), may not adequately cover the extent of tumor motion during the treatment, particularly for patients that exhibit a large respiratory variability. Inaccurate tumor localization may result in under-dosage of the tumor or over-dosage of the surrounding tissues. The purpose of this study is therefore to assess the degree of tumor under-dosage in case of regular and irregular breathing for proton radiotherapy using ITV-based treatment planning. We place a spherical lesion into a modified XCAT phantom that is also capable of producing 4D images based on irregular breathing, and move the tumor according to real tumor motion data, which is acquired over multiple days by tracking gold fiducial markers implanted into the lung tumors of patients. We derive ITVs by taking the union of all tumor positions during 6 s of tumor motion in the phantom using the first day patient tumor tracking data. This is equivalent to ITVs generated clinically from cine-mode 4D-CT MIP images. The treatment plans created for different ITVs are then implemented on dynamic phantoms with tumor motion governed by real tumor tracking data from consecutive days. By comparing gross tumor volume dose distribution on days of ‘treatment’ with the ITV dose distribution, we evaluate the deviation of the actually delivered dose from the predicted dose. Our results have shown that the proton treatment planning on ITV derived from pre-treatment cine-mode 4D-CT can result in under-dosage (dose covering 95% of volume) of the tumor by up to 25.7% over 3 min of treatment for the patient with irregular respiratory motion. Tumor under-dosage is less significant for

  17. Performance evaluation and optimization of BM4D-AV denoising algorithm for cone-beam CT images

    NASA Astrophysics Data System (ADS)

    Huang, Kuidong; Tian, Xiaofei; Zhang, Dinghua; Zhang, Hua

    2015-12-01

    The broadening application of cone-beam Computed Tomography (CBCT) in medical diagnostics and nondestructive testing, necessitates advanced denoising algorithms for its 3D images. The block-matching and four dimensional filtering algorithm with adaptive variance (BM4D-AV) is applied to the 3D image denoising in this research. To optimize it, the key filtering parameters of the BM4D-AV algorithm are assessed firstly based on the simulated CBCT images and a table of optimized filtering parameters is obtained. Then, considering the complexity of the noise in realistic CBCT images, possible noise standard deviations in BM4D-AV are evaluated to attain the chosen principle for the realistic denoising. The results of corresponding experiments demonstrate that the BM4D-AV algorithm with optimized parameters presents excellent denosing effect on the realistic 3D CBCT images.

  18. SU-E-T-330: To Analyze the Calculation Error of Live Dose-Volume Indices Applying 4D-CT in Radiotherapy for PTVs Within the Liver Completely

    SciTech Connect

    Gong, G; Liu, C; Yin, Y

    2014-06-01

    Purpose: To study the variation rule of normal liver dose-volume indices calculation for the liver malignancy patients whose plan target volumes were in the liver completely in all breath phases. Methods: Ten patients who accepted radiotherapy for malignant tumor were selected in our study. All patients underwent 4D-CT simulation and 3D-CT simulation in free breathing(FB). 4D-CT was sorted into 10 series CT images according to breath phase, named CT0, CT10 to CT90, respectively. And GTVs were contoured on different CT series, and the individual target volume(ITV) was obtained by merging 10 GTVs from 4D-CT. The PTVs were obtained from ITV applying margins. The PTVs were not beyond the boundary of liver in all breath phase observed by dynamic 4D-CT. The radiotherapy plans were designed and irradiation dose was calculated on 3D-CT images, and the livers were contoured on different series CT images and mapped to 3D-CT images applying rigid registration. To compare the dose-volume difference of livers based on distinct CT images. Results: (1)The liver volumes were similar on 4D-CT and 3D-CT images(CTFB 1485±500cm{sup 3}, CT0 1413±377cm{sup 3}, CT10 1409±396cm{sup 3}, CT20 1419±418cm{sup 3},CT30 1485±500cm{sup 3}, CT40 1438±392cm{sup 3}, CT50 1437±404cm{sup 3}, CT60 1439±409cm{sup 3}, CT70 1408±393cm{sup 3}, CT80 1384±397cm{sup 3}, CT90 1398±397cm{sup 3}; F=0.064,p=1.00) (2) The PTVs volume were 30.17±14.62cm{sup 3};(3) The mean dose and V5 to V10 of liver were similar among 4D-CT different series CT images(p>0.05), and the indices varied less than ±4% refer to liver on CT50. Conclusion: The calculation affection of liver dose-volume indices induced by breath motion were not significant for the PTV within liver completely as estimation before. And more objective prediction indices for radiation induced l.

  19. Spectral CT data acquisition with Medipix3.1

    NASA Astrophysics Data System (ADS)

    Walsh, M. F.; Nik, S. J.; Procz, S.; Pichotka, M.; Bell, S. T.; Bateman, C. J.; Doesburg, R. M. N.; De Ruiter, N.; Chernoglazov, A. I.; Panta, R. K.; Butler, A. P. H.; Butler, P. H.

    2013-10-01

    This paper describes the acquisition of spectral CT images using the Medipix3.1 in spectroscopic mode, in which the chip combines 2 × 2 pixel clusters to increase the number of energy thresholds and counters from 2 to 8. During preliminary measurements, it was observed that the temperature, DAC and equalisation stability of the Medipix3.1 outperformed the Medipix3.0, while maintaining similar imaging quality. In this paper, the Medipix3.1 chips were assembled in a quad (2 × 2) layout, with the four ASICs bump-bonded to a silicon semiconductor doped as an np-junction diode. To demonstrate the biological imaging quality that is possible with the Medipix3.1, an image of a mouse injected with gold nano-particle contrast agent was obtained. CT acquisition in spectroscopic mode was enabled and examined by imaging a customised phantom containing multiple contrast agents and biological materials. These acquisitions showed a limitation of imaging performance depending on the counter used. Despite this, identification of multiple materials in the phantom was demonstrated using an in-house material decomposition algorithm. Furthermore, gold nano-particles were separated from biological tissues and bones within the mouse by means of image rendering.

  20. Imaging and dosimetric errors in 4D PET/CT-guided radiotherapy from patient-specific respiratory patterns: a dynamic motion phantom end-to-end study

    NASA Astrophysics Data System (ADS)

    Bowen, S. R.; Nyflot, M. J.; Herrmann, C.; Groh, C. M.; Meyer, J.; Wollenweber, S. D.; Stearns, C. W.; Kinahan, P. E.; Sandison, G. A.

    2015-05-01

    Effective positron emission tomography / computed tomography (PET/CT) guidance in radiotherapy of lung cancer requires estimation and mitigation of errors due to respiratory motion. An end-to-end workflow was developed to measure patient-specific motion-induced uncertainties in imaging, treatment planning, and radiation delivery with respiratory motion phantoms and dosimeters. A custom torso phantom with inserts mimicking normal lung tissue and lung lesion was filled with [18F]FDG. The lung lesion insert was driven by six different patient-specific respiratory patterns or kept stationary. PET/CT images were acquired under motionless ground truth, tidal breathing motion-averaged (3D), and respiratory phase-correlated (4D) conditions. Target volumes were estimated by standardized uptake value (SUV) thresholds that accurately defined the ground-truth lesion volume. Non-uniform dose-painting plans using volumetrically modulated arc therapy were optimized for fixed normal lung and spinal cord objectives and variable PET-based target objectives. Resulting plans were delivered to a cylindrical diode array at rest, in motion on a platform driven by the same respiratory patterns (3D), or motion-compensated by a robotic couch with an infrared camera tracking system (4D). Errors were estimated relative to the static ground truth condition for mean target-to-background (T/Bmean) ratios, target volumes, planned equivalent uniform target doses, and 2%-2 mm gamma delivery passing rates. Relative to motionless ground truth conditions, PET/CT imaging errors were on the order of 10-20%, treatment planning errors were 5-10%, and treatment delivery errors were 5-30% without motion compensation. Errors from residual motion following compensation methods were reduced to 5-10% in PET/CT imaging, <5% in treatment planning, and <2% in treatment delivery. We have demonstrated that estimation of respiratory motion uncertainty and its propagation from PET/CT imaging to RT planning, and RT

  1. Imaging and dosimetric errors in 4D PET/CT-guided radiotherapy from patient-specific respiratory patterns: a dynamic motion phantom end-to-end study

    PubMed Central

    Bowen, S R; Nyflot, M J; Hermann, C; Groh, C; Meyer, J; Wollenweber, S D; Stearns, C W; Kinahan, P E; Sandison, G A

    2015-01-01

    Effective positron emission tomography/computed tomography (PET/CT) guidance in radiotherapy of lung cancer requires estimation and mitigation of errors due to respiratory motion. An end-to-end workflow was developed to measure patient-specific motion-induced uncertainties in imaging, treatment planning, and radiation delivery with respiratory motion phantoms and dosimeters. A custom torso phantom with inserts mimicking normal lung tissue and lung lesion was filled with [18F]FDG. The lung lesion insert was driven by 6 different patient-specific respiratory patterns or kept stationary. PET/CT images were acquired under motionless ground truth, tidal breathing motion-averaged (3D), and respiratory phase-correlated (4D) conditions. Target volumes were estimated by standardized uptake value (SUV) thresholds that accurately defined the ground-truth lesion volume. Non-uniform dose-painting plans using volumetrically modulated arc therapy (VMAT) were optimized for fixed normal lung and spinal cord objectives and variable PET-based target objectives. Resulting plans were delivered to a cylindrical diode array at rest, in motion on a platform driven by the same respiratory patterns (3D), or motion-compensated by a robotic couch with an infrared camera tracking system (4D). Errors were estimated relative to the static ground truth condition for mean target-to-background (T/Bmean) ratios, target volumes, planned equivalent uniform target doses (EUD), and 2%-2mm gamma delivery passing rates. Relative to motionless ground truth conditions, PET/CT imaging errors were on the order of 10–20%, treatment planning errors were 5–10%, and treatment delivery errors were 5–30% without motion compensation. Errors from residual motion following compensation methods were reduced to 5–10% in PET/CT imaging, < 5% in treatment planning, and < 2% in treatment delivery. We have demonstrated that estimation of respiratory motion uncertainty and its propagation from PET/CT imaging to RT

  2. SU-E-J-151: Dosimetric Evaluation of DIR Mapped Contours for Image Guided Adaptive Radiotherapy with 4D Cone-Beam CT

    SciTech Connect

    Balik, S; Weiss, E; Williamson, J; Hugo, G; Jan, N; Zhang, L; Roman, N; Christensen, G

    2014-06-01

    Purpose: To estimate dosimetric errors resulting from using contours deformably mapped from planning CT to 4D cone beam CT (CBCT) images for image-guided adaptive radiotherapy of locally advanced non-small cell lung cancer (NSCLC). Methods: Ten locally advanced non-small cell lung cancer (NSCLC) patients underwent one planning 4D fan-beam CT (4DFBCT) and weekly 4DCBCT scans. Multiple physicians delineated the gross tumor volume (GTV) and normal structures in planning CT images and only GTV in CBCT images. Manual contours were mapped from planning CT to CBCTs using small deformation, inverse consistent linear elastic (SICLE) algorithm for two scans in each patient. Two physicians reviewed and rated the DIR-mapped (auto) and manual GTV contours as clinically acceptable (CA), clinically acceptable after minor modification (CAMM) and unacceptable (CU). Mapped normal structures were visually inspected and corrected if necessary, and used to override tissue density for dose calculation. CTV (6mm expansion of GTV) and PTV (5mm expansion of CTV) were created. VMAT plans were generated using the DIR-mapped contours to deliver 66 Gy in 33 fractions with 95% and 100% coverage (V66) to PTV and CTV, respectively. Plan evaluation for V66 was based on manual PTV and CTV contours. Results: Mean PTV V66 was 84% (range 75% – 95%) and mean CTV V66 was 97% (range 93% – 100%) for CAMM scored plans (12 plans); and was 90% (range 80% – 95%) and 99% (range 95% – 100%) for CA scored plans (7 plans). The difference in V66 between CAMM and CA was significant for PTV (p = 0.03) and approached significance for CTV (p = 0.07). Conclusion: The quality of DIR-mapped contours directly impacted the plan quality for 4DCBCT-based adaptation. Larger safety margins may be needed when planning with auto contours for IGART with 4DCBCT images. Reseach was supported by NIH P01CA116602.

  3. Usefulness of four dimensional (4D) PET/CT imaging in the evaluation of thoracic lesions and in radiotherapy planning: Review of the literature.

    PubMed

    Sindoni, Alessandro; Minutoli, Fabio; Pontoriero, Antonio; Iatì, Giuseppe; Baldari, Sergio; Pergolizzi, Stefano

    2016-06-01

    In the past decade, Positron Emission Tomography (PET) has become a routinely used methodology for the assessment of solid tumors, which can detect functional abnormalities even before they become morphologically evident on conventional imaging. PET imaging has been reported to be useful in characterizing solitary pulmonary nodules, guiding biopsy, improving lung cancer staging, guiding therapy, monitoring treatment response and predicting outcome. This review focuses on the most relevant and recent literature findings, highlighting the current role of PET/CT and the evaluation of 4D-PET/CT modality for radiation therapy planning applications. Current evidence suggests that gross tumor volume delineation based on 4D-PET/CT information may be the best approach currently available for its delineation in thoracic cancers (lung and non-lung lesions). In our opinion, its use in this clinical setting is strongly encouraged, as it may improve patient treatment outcome in the setting of radiation therapy for cancers of the thoracic region, not only involving lung, but also lymph nodes and esophageal tissue. Literature results warrants further investigation in future prospective studies, especially in the setting of dose escalation. PMID:27133755

  4. Spectrotemporal CT data acquisition and reconstruction at low dose

    SciTech Connect

    Clark, Darin P.; Badea, Cristian T.; Lee, Chang-Lung; Kirsch, David G.

    2015-11-15

    Purpose: X-ray computed tomography (CT) is widely used, both clinically and preclinically, for fast, high-resolution anatomic imaging; however, compelling opportunities exist to expand its use in functional imaging applications. For instance, spectral information combined with nanoparticle contrast agents enables quantification of tissue perfusion levels, while temporal information details cardiac and respiratory dynamics. The authors propose and demonstrate a projection acquisition and reconstruction strategy for 5D CT (3D + dual energy + time) which recovers spectral and temporal information without substantially increasing radiation dose or sampling time relative to anatomic imaging protocols. Methods: The authors approach the 5D reconstruction problem within the framework of low-rank and sparse matrix decomposition. Unlike previous work on rank-sparsity constrained CT reconstruction, the authors establish an explicit rank-sparse signal model to describe the spectral and temporal dimensions. The spectral dimension is represented as a well-sampled time and energy averaged image plus regularly undersampled principal components describing the spectral contrast. The temporal dimension is represented as the same time and energy averaged reconstruction plus contiguous, spatially sparse, and irregularly sampled temporal contrast images. Using a nonlinear, image domain filtration approach, the authors refer to as rank-sparse kernel regression, the authors transfer image structure from the well-sampled time and energy averaged reconstruction to the spectral and temporal contrast images. This regularization strategy strictly constrains the reconstruction problem while approximately separating the temporal and spectral dimensions. Separability results in a highly compressed representation for the 5D data in which projections are shared between the temporal and spectral reconstruction subproblems, enabling substantial undersampling. The authors solved the 5D reconstruction

  5. SU-E-J-267: Weekly Volumetric and Dosimetric Changes in Adaptive Conformal Radiotherapy of Non-Small-Cell-Lung Cancer Using 4D CT and Gating

    SciTech Connect

    Li, Z; Shang, Q; Xiong, F; Zhang, X; Zhang, Q; Fu, S

    2014-06-01

    Purpose: This study was to evaluate the significance of weekly imageguided patient setup and to assess the volumetric and dosimetric changes in no-small-cell-lung cancer (NSCLC) patients treated with adaptive conformal radiotherapy (CRT). Methods: 9 NSCLC patients treated with 3D CRT underwent 4D CT-on-rail every five fractions. ITV was generated from three phases of the 4DCT (the end of exhalation, 25% before and after the end of exhalation). The margin of ITV to PTV is 5mm. 6 weekly CTs were acquired for each patient. The weekly CTs were fused with the planning CT by vertebrae. The couch shift was recorded for each weekly CT to evaluate the setup error. The gross tumor volumes (GTVs) were contoured on weekly CT images by a physician. Beams from the original plans were applied to weekly CTs to calculate the delivered doses. All patients underwent replanning after 20 fractions. Results: Among the total 54 CTs, the average setup error was 2.0± 1.7, 2.6± 2.1, 2.7± 2.2 mm in X, Y, and Z direction, respectively. The average volume of the primary GTV was reduced from 42.45 cc to 22.78 cc (47.04%) after 6 weeks. The maximal volume regression occurred between 15 and 20 fractions. Adaptive radiation therapy (ART) reduced the V20 and V5 of the lung by 33.5% and 16.89%, respectively. ART also reduced Dmean and D1/3 of the heart by 31.7% and 32.32%, respectively. Dmax of the spinal cord did not vary much during the treatment course. Conclusion: 5 mm margin is sufficient for 4D weekly CTguided radiotherapy in lung cancer. Tumor regression was observed in the majority of patients. ART significantly reduced the OARs dose. Our preliminary results indicated that an off-line ART approach is appropriate in clinical practice.

  6. Taking geoscience to the IMAX: 3D and 4D insight into geological processes using micro-CT

    NASA Astrophysics Data System (ADS)

    Dobson, Katherine; Dingwell, Don; Hess, Kai-Uwe; Withers, Philip; Lee, Peter; Pistone, Mattia; Fife, Julie; Atwood, Robert

    2015-04-01

    Geology is inherently dynamic, and full understanding of any geological system can only be achieved by considering the processes by which change occurs. Analytical limitations mean understanding has largely developed from ex situ analyses of the products of geological change, rather than of the processes themselves. Most methods essentially utilise "snap shot" sampling: and from thin section petrography to high resolution crystal chemical stratigraphy and field volcanology, we capture an incomplete view of a spatially and temporally variable system. Even with detailed experimental work, we can usually only analyse samples before and after we perform an experiment, as routine analysis methods are destructive. Serial sectioning and quenched experiments stopped at different stages can give some insight into the third and fourth dimension, but the true scaling of the processes from the laboratory to the 4D (3D + time) geosphere is still poorly understood. Micro computed tomography (XMT) can visualise the internal structures and spatial associations within geological samples non-destructively. With image resolutions of between 200 microns and 50 nanometres, tomography has the ability to provide a detailed sample assessment in 3D, and quantification of mineral associations, porosity, grain orientations, fracture alignments and many other features. This allows better understanding of the role of the complex geometries and associations within the samples, but the challenge of capturing the processes that generate and modify these structures remains. To capture processes, recent work has focused on developing experimental capability for in situ experiments on geological materials. Data presented will showcase examples from recent experiments where high speed synchrotron x-ray tomography has been used to acquire each 3D image in under 2 seconds. We present a suite of studies that showcase how it is now possible to take quantification of many geological processed into 3D and

  7. SU-D-201-07: Exploring the Utility of 4D FDG-PET/CT Scans in Design of Radiation Therapy Planning Compared with 3D PET/CT: A Prospective Study

    SciTech Connect

    Ma, C; Yin, Y

    2015-06-15

    Purpose: A method using four-dimensional(4D) PET/CT in design of radiation treatment planning was proposed and the target volume and radiation dose distribution changes relative to standard three-dimensional (3D) PET/CT were examined. Methods: A target deformable registration method was used by which the whole patient’s respiration process was considered and the effect of respiration motion was minimized when designing radiotherapy planning. The gross tumor volume of a non-small-cell lung cancer was contoured on the 4D FDG-PET/CT and 3D PET/CT scans by use of two different techniques: manual contouring by an experienced radiation oncologist using a predetermined protocol; another technique using a constant threshold of standardized uptake value (SUV) greater than 2.5. The target volume and radiotherapy dose distribution between VOL3D and VOL4D were analyzed. Results: For all phases, the average automatic and manually GTV volume was 18.61 cm3 (range, 16.39–22.03 cm3) and 31.29 cm3 (range, 30.11–35.55 cm3), respectively. The automatic and manually volume of merged IGTV were 27.82 cm3 and 49.37 cm3, respectively. For the manual contour, compared to 3D plan the mean dose for the left, right, and total lung of 4D plan have an average decrease 21.55%, 15.17% and 15.86%, respectively. The maximum dose of spinal cord has an average decrease 2.35%. For the automatic contour, the mean dose for the left, right, and total lung have an average decrease 23.48%, 16.84% and 17.44%, respectively. The maximum dose of spinal cord has an average decrease 1.68%. Conclusion: In comparison to 3D PET/CT, 4D PET/CT may better define the extent of moving tumors and reduce the contouring tumor volume thereby optimize radiation treatment planning for lung tumors.

  8. Fast analytic simulation toolkit for generation of 4D PET-MR data from real dynamic MR acquisitions

    NASA Astrophysics Data System (ADS)

    Tsoumpas, C.; Buerger, C.; Mollet, P.; Marsden, P. K.

    2011-09-01

    This work introduces and evaluates a fast analytic simulation toolkit (FAST) for simulating dynamic PET-MR data from real MR acquisitions. Realistic radiotracer values are assigned to segmented MR images. PET data are generated using analytic forward-projections (including attenuation and Poisson statistics) with the reconstruction software STIR, which is also used to produce the PET images that are spatially and temporally correlated with the real MR images. The simulation is compared with the GATE Monte Carlo package, which has more accurate physical modelling but it is 150 times slower compared to FAST for ten respiratory positions and 7000× slower, when repeating the simulation. The region of interest for mean values and coefficients of variation obtained with FAST and GATE, from 65 million and 104 million coincidences, respectively, were compared. Agreement between the two different simulation methods is good. In particular, the percentage differences of the mean values are: 10% for liver, and 19% for the myocardium and a warm lesion. The utility of FAST is demonstrated with the simulation of multiple volunteers with different breathing patterns. The package will be used for studying the performance of reconstruction, motion correction and attenuation correction algorithms for dynamic simultaneous PET-MR data.

  9. Determination of prospective displacement-based gate threshold for respiratory-gated radiation delivery from retrospective phase-based gate threshold selected at 4D CT simulation

    SciTech Connect

    Vedam, S.; Archambault, L.; Starkschall, G.; Mohan, R.; Beddar, S.

    2007-11-15

    Four-dimensional (4D) computed tomography (CT) imaging has found increasing importance in the localization of tumor and surrounding normal structures throughout the respiratory cycle. Based on such tumor motion information, it is possible to identify the appropriate phase interval for respiratory gated treatment planning and delivery. Such a gating phase interval is determined retrospectively based on tumor motion from internal tumor displacement. However, respiratory-gated treatment is delivered prospectively based on motion determined predominantly from an external monitor. Therefore, the simulation gate threshold determined from the retrospective phase interval selected for gating at 4D CT simulation may not correspond to the delivery gate threshold that is determined from the prospective external monitor displacement at treatment delivery. The purpose of the present work is to establish a relationship between the thresholds for respiratory gating determined at CT simulation and treatment delivery, respectively. One hundred fifty external respiratory motion traces, from 90 patients, with and without audio-visual biofeedback, are analyzed. Two respiratory phase intervals, 40%-60% and 30%-70%, are chosen for respiratory gating from the 4D CT-derived tumor motion trajectory. From residual tumor displacements within each such gating phase interval, a simulation gate threshold is defined based on (a) the average and (b) the maximum respiratory displacement within the phase interval. The duty cycle for prospective gated delivery is estimated from the proportion of external monitor displacement data points within both the selected phase interval and the simulation gate threshold. The delivery gate threshold is then determined iteratively to match the above determined duty cycle. The magnitude of the difference between such gate thresholds determined at simulation and treatment delivery is quantified in each case. Phantom motion tests yielded coincidence of simulation

  10. Estimation of Cardiac Respiratory-Motion by Semi-Automatic Segmentation and Registration of Non-Contrast-Enhanced 4D-CT Cardiac Datasets

    PubMed Central

    Dey, Joyoni; Pan, Tinsu; Choi, David J.; Robotis, Dennis; Smyczynski, Mark S.; Pretorius, P. Hendrik; King, Michael A.

    2010-01-01

    The goal of this work is to investigate, for a large set of patients, the motion of the heart with respiration during free-breathing supine medical imaging. For this purpose we analyzed the motion of the heart in 32 non-contrast enhanced respiratory-gated 4D-CT datasets acquired during quiet unconstrained breathing. The respiratory-gated CT images covered the cardiac region and were acquired at each of 10 stages of the respiratory cycle, with the first stage being end-inspiration. We devised a 3-D semi-automated segmentation algorithm that segments the heart in the 4D-CT datasets acquired without contrast enhancement for use in estimating respiratory motion of the heart. Our semi-automated segmentation results were compared against interactive hand segmentations of the coronal slices by a cardiologist and a radiologist. The pairwise difference in segmentation among the algorithm and the physicians was on the average 11% and 10% of the total average segmented volume across the patient, with a couple of patients as outliers above the 95% agreement limit. The mean difference among the two physicians was 8% with an outlier above the 95% agreement limit. The 3-D segmentation was an order of magnitude faster than the Physicians’ manual segmentation and represents significant reduction of Physicians’ time. The segmented first stages of respiration were used in 12 degree-of-freedom (DOF) affine registration to estimate the motion at each subsequent stage of respiration. The registration results from the 32 patients indicate that the translation in the superior-inferior direction was the largest component motion, with a maximum of 10.7 mm, mean of 6.4 mm, and standard deviation of 2.2 mm. Translation in the anterior-posterior direction was the next largest component of motion, with a maximum of 4.0 mm, mean of 1.7 mm, and standard deviation of 1.0 mm. Rotation about the right-left axis was on average the largest component of rotation observed, with a maximum of 4

  11. Monitoring in vivo (re)modeling: a computational approach using 4D microCT data to quantify bone surface movements.

    PubMed

    Birkhold, Annette I; Razi, Hajar; Weinkamer, Richard; Duda, Georg N; Checa, Sara; Willie, Bettina M

    2015-06-01

    Bone undergoes continual damage repair and structural adaptation to changing external loads with the aim of maintaining skeletal integrity throughout life. The ability to monitor bone (re)modeling would allow for a better understanding in how various pathologies and interventions affect bone turnover and subsequent bone strength. To date, however, current methods to monitor bone (re)modeling over time and in space are limited. We propose a novel method to visualize and quantify bone turnover, based on in vivo microCT imaging and a 4D computational approach. By in vivo tracking of spatially correlated formation and resorption sites over time it classifies bone restructuring into (re)modeling sequences, the spatially and temporally linked sequences of formation, resorption and quiescent periods on the bone surface. The microCT based method was validated using experimental data from an in vivo mouse tibial loading model and ex vivo data of the mouse tibia. In this application, the method allows the visualization of time-resolved cortical (re)modeling and the quantification of short-term and long-term modeling on the endocortical and periosteal surface at the mid-diaphysis of loaded and control mice tibiae. Both short-term and long-term modeling processes, independent formation and resorption events, could be monitored and modeling (spatially not correlated formation and resorption) and remodeling (resorption followed by new formation at the same site) could be distinguished on the bone surface. This novel method that combines in vivo microCT with a computational approach is a powerful tool to monitor bone turnover in animal models now and is waiting to be applied to human patients in the near future. PMID:25746796

  12. Ultra-low dose CT attenuation correction for PET/CT: analysis of sparse view data acquisition and reconstruction algorithms

    NASA Astrophysics Data System (ADS)

    Rui, Xue; Cheng, Lishui; Long, Yong; Fu, Lin; Alessio, Adam M.; Asma, Evren; Kinahan, Paul E.; De Man, Bruno

    2015-09-01

    For PET/CT systems, PET image reconstruction requires corresponding CT images for anatomical localization and attenuation correction. In the case of PET respiratory gating, multiple gated CT scans can offer phase-matched attenuation and motion correction, at the expense of increased radiation dose. We aim to minimize the dose of the CT scan, while preserving adequate image quality for the purpose of PET attenuation correction by introducing sparse view CT data acquisition. We investigated sparse view CT acquisition protocols resulting in ultra-low dose CT scans designed for PET attenuation correction. We analyzed the tradeoffs between the number of views and the integrated tube current per view for a given dose using CT and PET simulations of a 3D NCAT phantom with lesions inserted into liver and lung. We simulated seven CT acquisition protocols with {984, 328, 123, 41, 24, 12, 8} views per rotation at a gantry speed of 0.35 s. One standard dose and four ultra-low dose levels, namely, 0.35 mAs, 0.175 mAs, 0.0875 mAs, and 0.043 75 mAs, were investigated. Both the analytical Feldkamp, Davis and Kress (FDK) algorithm and the Model Based Iterative Reconstruction (MBIR) algorithm were used for CT image reconstruction. We also evaluated the impact of sinogram interpolation to estimate the missing projection measurements due to sparse view data acquisition. For MBIR, we used a penalized weighted least squares (PWLS) cost function with an approximate total-variation (TV) regularizing penalty function. We compared a tube pulsing mode and a continuous exposure mode for sparse view data acquisition. Global PET ensemble root-mean-squares-error (RMSE) and local ensemble lesion activity error were used as quantitative evaluation metrics for PET image quality. With sparse view sampling, it is possible to greatly reduce the CT scan dose when it is primarily used for PET attenuation correction with little or no measureable effect on the PET image. For the four ultra-low dose

  13. Ultra-low dose CT attenuation correction for PET/CT: analysis of sparse view data acquisition and reconstruction algorithms.

    PubMed

    Rui, Xue; Cheng, Lishui; Long, Yong; Fu, Lin; Alessio, Adam M; Asma, Evren; Kinahan, Paul E; De Man, Bruno

    2015-10-01

    For PET/CT systems, PET image reconstruction requires corresponding CT images for anatomical localization and attenuation correction. In the case of PET respiratory gating, multiple gated CT scans can offer phase-matched attenuation and motion correction, at the expense of increased radiation dose. We aim to minimize the dose of the CT scan, while preserving adequate image quality for the purpose of PET attenuation correction by introducing sparse view CT data acquisition.We investigated sparse view CT acquisition protocols resulting in ultra-low dose CT scans designed for PET attenuation correction. We analyzed the tradeoffs between the number of views and the integrated tube current per view for a given dose using CT and PET simulations of a 3D NCAT phantom with lesions inserted into liver and lung. We simulated seven CT acquisition protocols with {984, 328, 123, 41, 24, 12, 8} views per rotation at a gantry speed of 0.35 s. One standard dose and four ultra-low dose levels, namely, 0.35 mAs, 0.175 mAs, 0.0875 mAs, and 0.043 75 mAs, were investigated. Both the analytical Feldkamp, Davis and Kress (FDK) algorithm and the Model Based Iterative Reconstruction (MBIR) algorithm were used for CT image reconstruction. We also evaluated the impact of sinogram interpolation to estimate the missing projection measurements due to sparse view data acquisition. For MBIR, we used a penalized weighted least squares (PWLS) cost function with an approximate total-variation (TV) regularizing penalty function. We compared a tube pulsing mode and a continuous exposure mode for sparse view data acquisition. Global PET ensemble root-mean-squares-error (RMSE) and local ensemble lesion activity error were used as quantitative evaluation metrics for PET image quality.With sparse view sampling, it is possible to greatly reduce the CT scan dose when it is primarily used for PET attenuation correction with little or no measureable effect on the PET image. For the four ultra-low dose levels

  14. TU-F-BRF-07: Accuracy of Routine Treatment Planning 4D and DIBH CT Delineation of the Left Anterior Descending Artery in Radiotherapy

    SciTech Connect

    White, B; Lin, L; Freedmen, G; Both, S; Vennarini, S

    2014-06-15

    Purpose: To assess the feasibility of routine treatment planning 4DCT and deep inspiration breath-hold (DIBH) to accurately contour the left anterior descending artery (LAD), a primary indicator of cardiac toxicity, for radiotherapy treatment planning of breast cancer. Methods: Ten subjects were imaged with a cardiac-gated MRI protocol to determine the displacement of a ROI that included the LAD. The subjects performed a series of breath-hold maneuvers to obtain short-axis and radial views, which were resampled to create a 3D-volume. Tissue motion was determined using a multi-resolution 3D optical flow deformable image registration algorithm. The ROI motion was then used as a spatial boundary to characterize the blurring motion of the LAD in ten patients during clinical 4DCT and DIBH protocols. A radiologist contoured the LAD. Coronary motion-induced blurring artifacts were quantified by applying an unsharp filter to accentuate the LAD despite motion-blurring. The 4DCT maximum inhalation and exhalation respiratory phases were co-registered to determine the LAD displacement during tidal respiration, as visualized in 4DCT. Results: The average 90{sup th} percentile heart motion for the ROI was 0.7±0.1mm(LR), 1.3±0.6mm(SI), 0.6±0.2mm(AP) in the cardiac-gated MRI cohort. The average relative increase in the number of voxels comprising the LAD contour was 69.4±4.5% for the DIBH. During tidal respiration, the average relative increase in the LAD contour was 69.3±5.9% and 67.9±4.6% for inhalation and exhalation respiratory phases respectively. The average 90{sup th} percentile LAD motion was 4.8±1.1mm(LR), 0.9±0.4mm(SI), 1.9±0.6mm(AP) for the 4DCT cohort, in the absence of cardiac-gating. Conclusion: Uncompensated coronary motion was the dominant form of motion blurring present in the CT images due to the high frequency of the cardiac cycle relative to the respiratory cycle. The 4D and DIBH CT contour delineation of the LAD was consistently overestimated without

  15. Acquisition, preprocessing, and reconstruction of ultralow dose volumetric CT scout for organ-based CT scan planning

    SciTech Connect

    Yin, Zhye De Man, Bruno; Yao, Yangyang; Wu, Mingye; Montillo, Albert; Edic, Peter M.; Kalra, Mannudeep

    2015-05-15

    Purpose: Traditionally, 2D radiographic preparatory scan images (scout scans) are used to plan diagnostic CT scans. However, a 3D CT volume with a full 3D organ segmentation map could provide superior information for customized scan planning and other purposes. A practical challenge is to design the volumetric scout acquisition and processing steps to provide good image quality (at least good enough to enable 3D organ segmentation) while delivering a radiation dose similar to that of the conventional 2D scout. Methods: The authors explored various acquisition methods, scan parameters, postprocessing methods, and reconstruction methods through simulation and cadaver data studies to achieve an ultralow dose 3D scout while simultaneously reducing the noise and maintaining the edge strength around the target organ. Results: In a simulation study, the 3D scout with the proposed acquisition, preprocessing, and reconstruction strategy provided a similar level of organ segmentation capability as a traditional 240 mAs diagnostic scan, based on noise and normalized edge strength metrics. At the same time, the proposed approach delivers only 1.25% of the dose of a traditional scan. In a cadaver study, the authors’ pictorial-structures based organ localization algorithm successfully located the major abdominal-thoracic organs from the ultralow dose 3D scout obtained with the proposed strategy. Conclusions: The authors demonstrated that images with a similar degree of segmentation capability (interpretability) as conventional dose CT scans can be achieved with an ultralow dose 3D scout acquisition and suitable postprocessing. Furthermore, the authors applied these techniques to real cadaver CT scans with a CTDI dose level of less than 0.1 mGy and successfully generated a 3D organ localization map.

  16. Acquisition of Character Translation Rules for Supporting SNOMED CT Localizations.

    PubMed

    Miñarro-Giménez, Jose Antonio; Hellrich, Johannes; Schulz, Stefan

    2015-01-01

    Translating huge medical terminologies like SNOMED CT is costly and time consuming. We present a methodology that acquires substring substitution rules for single words, based on the known similarity between medical words and their translations, due to their common Latin / Greek origin. Character translation rules are automatically acquired from pairs of English words and their automated translations to German. Using a training set with single words extracted from SNOMED CT as input we obtained a list of 268 translation rules. The evaluation of these rules improved the translation of 60% of words compared to Google Translate and 55% of translated words that exactly match the right translations. On a subset of words where machine translation had failed, our method improves translation in 56% of cases, with 27% exactly matching the gold standard. PMID:25991218

  17. Tracking 'differential organ motion' with a 'breathing' multileaf collimator: magnitude of problem assessed using 4D CT data and a motion-compensation strategy

    NASA Astrophysics Data System (ADS)

    McClelland, J. R.; Webb, S.; McQuaid, D.; Binnie, D. M.; Hawkes, D. J.

    2007-08-01

    Intrafraction tumour (e.g. lung) motion due to breathing can, in principle, be compensated for by applying identical breathing motions to the leaves of a multileaf collimator (MLC) as intensity-modulated radiation therapy is delivered by the dynamic MLC (DMLC) technique. A difficulty arising, however, is that irradiated voxels, which are in line with a bixel at one breathing phase (at which the treatment plan has been made), may move such that they cease to be in line with that breathing bixel at another phase. This is the phenomenon of differential voxel motion and existing tracking solutions have ignored this very real problem. There is absolutely no tracking solution to the problem of compensating for differential voxel motion. However, there is a strategy that can be applied in which the leaf breathing is determined to minimize the geometrical mismatch in a least-squares sense in irradiating differentially-moving voxels. A 1D formulation in very restricted circumstances is already in the literature and has been applied to some model breathing situations which can be studied analytically. These are, however, highly artificial. This paper presents the general 2D formulation of the problem including allowing different importance factors to be applied to planning target volume and organ at risk (or most generally) each voxel. The strategy also extends the literature strategy to the situation where the number of voxels connecting to a bixel is a variable. Additionally the phenomenon of 'cross-leaf-track/channel' voxel motion is formally addressed. The general equations are presented and analytic results are given for some 1D, artificially contrived, motions based on the Lujan equations of breathing motion. Further to this, 3D clinical voxel motion data have been extracted from 4D CT measurements to both assess the magnitude of the problem of 2D motion perpendicular to the beam-delivery axis in clinical practice and also to find the 2D optimum breathing-leaf strategy

  18. TH-E-17A-09: High Quality and Artifact-Free 4D Cone Beam CT and Its Application in Adaptive Treatment Planning

    SciTech Connect

    Niu, K; Li, K; Smilowitz, J; Chen, G

    2014-06-15

    Purpose: To develop a high quality 4D cone beam CT (4DCBCT) method that is immune to patient/couch truncations and to investigate its application in adaptive replanning of lung XRT. Methods: In this study, IRB-approved human subject CBCT data was acquired using a Varian on-board imager with 1 minute rotation time. The acquired projection data was retrospectively sorted into 20 respiratory phase bins, from which 4DCBCT images with high SNR and high temporal resolution were generated using Prior Image Constrained Compressed Sensing (PICCS). Couch and patient truncations generate strong data inconsistency in the projection data and artifacts in the 4DCBCT image. They were addressed using an adaptive PICCS method. The artifact-free PICCS-4DCBCT images were used to generate adaptive treatment plans for the same patient at the 10th (day 21) and 30th (day 47) fractions. Dosimetric impacts with and without PICCS- 4DCBCT were evaluated by isodose distributions, DVHs, and other dosimetric factors. Results: The adaptive PICCS-4DCBCT method improves image quality by removing residue truncation artifacts; measured universal image quality increased 37%. The isodose lines and DVHs with PICCS-4DCBCT-based adaptive replanning were significantly more conformal to PTV than without replanning due to changes in patient anatomy caused by progress of the treatment. The mean dose to PTV at the 10th fraction was 63.1Gy with replanning and 64.2Gy without replanning, where the prescribed dose was 60Gy, in 2Gy × 30 fractions. The mean dose to PTV at the 30th fraction was 61.6Gy with replanning and 64.9Gy without replanning. Lung V20 was 37.1%, 41.9% and 43.3% for original plan, 10th fraction plan and 30th fraction plan; with re-planning, Lung V20 was 37.1%, 32%, 27.8%. Conclusion: 4DCBCT imaging using adaptive PICCS is able to generate high quality, artifact-free images that potentially can be used to create replanning for improving radiotherapy of the lung. K Niu, K Li, J Smilowitz: Nothing

  19. Comparison of blood flow models and acquisitions for quantitative myocardial perfusion estimation from dynamic CT.

    PubMed

    Bindschadler, Michael; Modgil, Dimple; Branch, Kelley R; La Riviere, Patrick J; Alessio, Adam M

    2014-04-01

    Myocardial blood flow (MBF) can be estimated from dynamic contrast enhanced (DCE) cardiac CT acquisitions, leading to quantitative assessment of regional perfusion. The need for low radiation dose and the lack of consensus on MBF estimation methods motivates this study to refine the selection of acquisition protocols and models for CT-derived MBF. DCE cardiac CT acquisitions were simulated for a range of flow states (MBF = 0.5, 1, 2, 3 ml (min g)(-1), cardiac output = 3, 5, 8 L min(-1)). Patient kinetics were generated by a mathematical model of iodine exchange incorporating numerous physiological features including heterogenenous microvascular flow, permeability and capillary contrast gradients. CT acquisitions were simulated for multiple realizations of realistic x-ray flux levels. CT acquisitions that reduce radiation exposure were implemented by varying both temporal sampling (1, 2, and 3 s sampling intervals) and tube currents (140, 70, and 25 mAs). For all acquisitions, we compared three quantitative MBF estimation methods (two-compartment model, an axially-distributed model, and the adiabatic approximation to the tissue homogeneous model) and a qualitative slope-based method. In total, over 11 000 time attenuation curves were used to evaluate MBF estimation in multiple patient and imaging scenarios. After iodine-based beam hardening correction, the slope method consistently underestimated flow by on average 47.5% and the quantitative models provided estimates with less than 6.5% average bias and increasing variance with increasing dose reductions. The three quantitative models performed equally well, offering estimates with essentially identical root mean squared error (RMSE) for matched acquisitions. MBF estimates using the qualitative slope method were inferior in terms of bias and RMSE compared to the quantitative methods. MBF estimate error was equal at matched dose reductions for all quantitative methods and range of techniques evaluated. This

  20. Comparison of blood flow models and acquisitions for quantitative myocardial perfusion estimation from dynamic CT

    NASA Astrophysics Data System (ADS)

    Bindschadler, Michael; Modgil, Dimple; Branch, Kelley R.; La Riviere, Patrick J.; Alessio, Adam M.

    2014-04-01

    Myocardial blood flow (MBF) can be estimated from dynamic contrast enhanced (DCE) cardiac CT acquisitions, leading to quantitative assessment of regional perfusion. The need for low radiation dose and the lack of consensus on MBF estimation methods motivates this study to refine the selection of acquisition protocols and models for CT-derived MBF. DCE cardiac CT acquisitions were simulated for a range of flow states (MBF = 0.5, 1, 2, 3 ml (min g)-1, cardiac output = 3, 5, 8 L min-1). Patient kinetics were generated by a mathematical model of iodine exchange incorporating numerous physiological features including heterogenenous microvascular flow, permeability and capillary contrast gradients. CT acquisitions were simulated for multiple realizations of realistic x-ray flux levels. CT acquisitions that reduce radiation exposure were implemented by varying both temporal sampling (1, 2, and 3 s sampling intervals) and tube currents (140, 70, and 25 mAs). For all acquisitions, we compared three quantitative MBF estimation methods (two-compartment model, an axially-distributed model, and the adiabatic approximation to the tissue homogeneous model) and a qualitative slope-based method. In total, over 11 000 time attenuation curves were used to evaluate MBF estimation in multiple patient and imaging scenarios. After iodine-based beam hardening correction, the slope method consistently underestimated flow by on average 47.5% and the quantitative models provided estimates with less than 6.5% average bias and increasing variance with increasing dose reductions. The three quantitative models performed equally well, offering estimates with essentially identical root mean squared error (RMSE) for matched acquisitions. MBF estimates using the qualitative slope method were inferior in terms of bias and RMSE compared to the quantitative methods. MBF estimate error was equal at matched dose reductions for all quantitative methods and range of techniques evaluated. This suggests that

  1. Contrast medium administration and image acquisition parameters in renal CT angiography: what radiologists need to know

    PubMed Central

    Saade, Charbel; Deeb, Ibrahim Alsheikh; Mohamad, Maha; Al-Mohiy, Hussain; El-Merhi, Fadi

    2016-01-01

    Over the last decade, exponential advances in computed tomography (CT) technology have resulted in improved spatial and temporal resolution. Faster image acquisition enabled renal CT angiography to become a viable and effective noninvasive alternative in diagnosing renal vascular pathologies. However, with these advances, new challenges in contrast media administration have emerged. Poor synchronization between scanner and contrast media administration have reduced the consistency in image quality with poor spatial and contrast resolution. Comprehensive understanding of contrast media dynamics is essential in the design and implementation of contrast administration and image acquisition protocols. This review includes an overview of the parameters affecting renal artery opacification and current protocol strategies to achieve optimal image quality during renal CT angiography with iodinated contrast media, with current safety issues highlighted. PMID:26728701

  2. High-pitch spiral acquisition: a new scan mode for coronary CT angiography.

    PubMed

    Achenbach, Stephan; Marwan, Mohamed; Schepis, Tiziano; Pflederer, Tobias; Bruder, Herbert; Allmendinger, Thomas; Petersilka, Martin; Anders, Katharina; Lell, Michael; Kuettner, Axel; Ropers, Dieter; Daniel, Werner G; Flohr, Thomas

    2009-01-01

    Coronary CT angiography allows high-quality imaging of the coronary arteries when state-of-the-art CT systems are used. However, radiation exposure has been a concern. We describe a new scan mode that uses a very high-pitch spiral acquisition, "Flash Spiral," which has been developed specifically for low-dose imaging with dual-source CT. The scan mode uses a pitch of 3.2 to acquire a spiral CT data set, while covering the entire volume of the heart in one cardiac cycle. Data acquisition is prospectively triggered by the electrocardiogram and starts in late systole to be completed within one cardiac cycle. Images are reconstructed with a temporal resolution that corresponds to one-quarter of the gantry rotation time. Throughout the data set, subsequent images are reconstructed at later time instants in the cardiac cycle. In a patient with a heart rate of 49 beats/min, the Flash Spiral scan mode was used with a first-generation dual-source CT system and allowed artifact-free visualization of the coronary arteries with a radiation exposure of 1.7 mSv for a 12-cm scan range at 120 kVp tube voltage. PMID:19332343

  3. Quality Assurance of 4D-CT Scan Techniques in Multicenter Phase III Trial of Surgery Versus Stereotactic Radiotherapy (Radiosurgery or Surgery for Operable Early Stage (Stage 1A) Non-Small-Cell Lung Cancer [ROSEL] Study)

    SciTech Connect

    Hurkmans, Coen W.; Lieshout, Maarten van; Schuring, Danny; Heumen, Marielle J.T. van; Cuijpers, Johan P.; Lagerwaard, Frank J.; Widder, Joachim; Heide, Uulke A. van der; Senan, Suresh

    2011-07-01

    Purpose: To determine the accuracy of four-dimensional computed tomography (4D-CT) scanning techniques in institutions participating in a Phase III trial of surgery vs. stereotactic radiotherapy (SBRT) for lung cancer. Methods and Materials: All 9 centers performed a 4D-CT scan of a motion phantom (Quasar, Modus Medical Devices) in accordance with their in-house imaging protocol for SBRT. A cylindrical cedar wood insert with plastic spheres of 15 mm (o15) and 30 mm (o30) diameter was moved in a cosine-based pattern, with an extended period in the exhale position to mimic the actual breathing motion. A range of motion of R = 15 and R = 25 mm and breathing period of T = 3 and T = 6 s were used. Positional and volumetric imaging accuracy was analyzed using Pinnacle version 8.1x at various breathing phases, including the mid-ventilation phase and maximal intensity projections of the spheres. Results: Imaging using eight CT scanners (Philips, Siemens, GE) and one positron emission tomography-CT scanner (Institution 3, Siemens) was investigated. The imaging protocols varied widely among the institutions. No strong correlation was found between the specific scan protocol parameters and the observed results. Deviations in the maximal intensity projection volumes averaged 1.9% (starting phase of the breathing cycle [o]15, R = 15), 12.3% (o15, R = 25), and -0.9% (o30, R = 15). The end-expiration volume deviations (13.4%, o15 and 2.5%, o30), were, on average, smaller than the end-inspiration deviations (20.7%, o15 and 4.5%, o30), which, in turn, were smaller than the mid-ventilation deviations (32.6%, o15 and 8.0%, o30). A slightly larger variation in the mid-ventilation origin position was observed (mean, -0.2 mm; range, -3.6-4.2) than in the maximal intensity projection origin position (mean, -0.1 mm; range, -2.5-2.5). The range of motion was generally underestimated (mean, -1.5 mm; range, -5.5-1). Conclusions: Notable differences were seen in the 4D-CT imaging protocols

  4. SU-E-J-123: Assessing Segmentation Accuracy of Internal Volumes and Sub-Volumes in 4D PET/CT of Lung Tumors Using a Novel 3D Printed Phantom

    SciTech Connect

    Soultan, D; Murphy, J; James, C; Hoh, C; Moiseenko, V; Cervino, L; Gill, B

    2015-06-15

    Purpose: To assess the accuracy of internal target volume (ITV) segmentation of lung tumors for treatment planning of simultaneous integrated boost (SIB) radiotherapy as seen in 4D PET/CT images, using a novel 3D-printed phantom. Methods: The insert mimics high PET tracer uptake in the core and 50% uptake in the periphery, by using a porous design at the periphery. A lung phantom with the insert was placed on a programmable moving platform. Seven breathing waveforms of ideal and patient-specific respiratory motion patterns were fed to the platform, and 4D PET/CT scans were acquired of each of them. CT images were binned into 10 phases, and PET images were binned into 5 phases following the clinical protocol. Two scenarios were investigated for segmentation: a gate 30–70 window, and no gating. The radiation oncologist contoured the outer ITV of the porous insert with on CT images, while the internal void volume with 100% uptake was contoured on PET images for being indistinguishable from the outer volume in CT images. Segmented ITVs were compared to the expected volumes based on known target size and motion. Results: 3 ideal breathing patterns, 2 regular-breathing patient waveforms, and 2 irregular-breathing patient waveforms were used for this study. 18F-FDG was used as the PET tracer. The segmented ITVs from CT closely matched the expected motion for both no gating and gate 30–70 window, with disagreement of contoured ITV with respect to the expected volume not exceeding 13%. PET contours were seen to overestimate volumes in all the cases, up to more than 40%. Conclusion: 4DPET images of a novel 3D printed phantom designed to mimic different uptake values were obtained. 4DPET contours overestimated ITV volumes in all cases, while 4DCT contours matched expected ITV volume values. Investigation of the cause and effects of the discrepancies is undergoing.

  5. Impact of incorporating visual biofeedback in 4D MRI.

    PubMed

    To, David T; Kim, Joshua P; Price, Ryan G; Chetty, Indrin J; Glide-Hurst, Carri K

    2016-01-01

    Precise radiation therapy (RT) for abdominal lesions is complicated by respiratory motion and suboptimal soft tissue contrast in 4D CT. 4D MRI offers improved con-trast although long scan times and irregular breathing patterns can be limiting. To address this, visual biofeedback (VBF) was introduced into 4D MRI. Ten volunteers were consented to an IRB-approved protocol. Prospective respiratory-triggered, T2-weighted, coronal 4D MRIs were acquired on an open 1.0T MR-SIM. VBF was integrated using an MR-compatible interactive breath-hold control system. Subjects visually monitored their breathing patterns to stay within predetermined tolerances. 4D MRIs were acquired with and without VBF for 2- and 8-phase acquisitions. Normalized respiratory waveforms were evaluated for scan time, duty cycle (programmed/acquisition time), breathing period, and breathing regularity (end-inhale coefficient of variation, EI-COV). Three reviewers performed image quality assessment to compare artifacts with and without VBF. Respiration-induced liver motion was calculated via centroid difference analysis of end-exhale (EE) and EI liver contours. Incorporating VBF reduced 2-phase acquisition time (4.7 ± 1.0 and 5.4 ± 1.5 min with and without VBF, respectively) while reducing EI-COV by 43.8% ± 16.6%. For 8-phase acquisitions, VBF reduced acquisition time by 1.9 ± 1.6 min and EI-COVs by 38.8% ± 25.7% despite breathing rate remaining similar (11.1 ± 3.8 breaths/min with vs. 10.5 ± 2.9 without). Using VBF yielded higher duty cycles than unguided free breathing (34.4% ± 5.8% vs. 28.1% ± 6.6%, respectively). Image grading showed that out of 40 paired evaluations, 20 cases had equivalent and 17 had improved image quality scores with VBF, particularly for mid-exhale and EI. Increased liver excursion was observed with VBF, where superior-inferior, anterior-posterior, and left-right EE-EI displacements were 14.1± 5.8, 4.9 ± 2.1, and 1.5 ± 1.0 mm, respectively, with VBF compared to 11.9

  6. Phase impact factor: a novel parameter for determining optimal CT phase in 4D radiation therapy treatment planning for mobile lung cancer

    NASA Astrophysics Data System (ADS)

    Song, Yulin; Huang, Xiaolei; Mueller, Boris; Mychalczak, Borys

    2008-03-01

    Due to respiratory motion, lung tumor can move up to several centimeters. If respiratory motion is not carefully considered during the radiation treatment planning, the highly conformal dose distribution with steep gradients could miss the target. To address this issue, the common strategy is to add a population-derived safety margin to the gross tumor volume (GTV). However, during a free breathing CT simulation, the images could be acquired at any phase of a breathing cycle. With such a generalized uniform margin, the planning target volume (PTV) may either include more normal lung tissue than required or miss the GTV at certain phases of a breathing cycle. Recently, respiration correlated CT (4DCT) has been developed and implemented. With 4DCT, it is now possible to trace the tumor 3D trajectories during a breathing cycle and to define the tumor volume as the union of these 3D trajectories. The tumor volume defined in this way is called the internal target volume (ITV). In this study, we introduced a novel parameter, the phase impact factor (PIF), to determine the optimal CT phase for intensity modulated radiation therapy (IMRT) treatment planning for lung cancer. A minimum PIF yields a minimum probability for the GTV to move out of the ITV during the course of an IMRT treatment, providing a minimum probability of a geometric miss. Once the CT images with the optimal phase were determined, an IMRT plan with three to five co-planner beams was computed and optimized using the inverse treatment planning technique.

  7. Multienergy CT acquisition and reconstruction with a stepped tube potential scan

    SciTech Connect

    Shen, Le; Xing, Yuxiang

    2015-01-15

    Purpose: Based on an energy-dependent property of matter, one may obtain a pseudomonochromatic attenuation map, a material composition image, an electron-density distribution, and an atomic number image using a dual- or multienergy computed tomography (CT) scan. Dual- and multienergy CT scans broaden the potential of x-ray CT imaging. The development of such systems is very useful in both medical and industrial investigations. In this paper, the authors propose a new dual- and multienergy CT system design (segmental multienergy CT, SegMECT) using an innovative scanning scheme that is conveniently implemented on a conventional single-energy CT system. The two-step-energy dual-energy CT can be regarded as a special case of SegMECT. A special reconstruction method is proposed to support SegMECT. Methods: In their SegMECT, a circular trajectory in a CT scan is angularly divided into several arcs. The x-ray source is set to a different tube voltage for each arc of the trajectory. Thus, the authors only need to make a few step changes to the x-ray energy during the scan to complete a multienergy data acquisition. With such a data set, the image reconstruction might suffer from severe limited-angle artifacts if using conventional reconstruction methods. To solve the problem, they present a new prior-image-based reconstruction technique using a total variance norm of a quotient image constraint. On the one hand, the prior extracts structural information from all of the projection data. On the other hand, the effect from a possibly imprecise intensity level of the prior can be mitigated by minimizing the total variance of a quotient image. Results: The authors present a new scheme for a SegMECT configuration and establish a reconstruction method for such a system. Both numerical simulation and a practical phantom experiment are conducted to validate the proposed reconstruction method and the effectiveness of the system design. The results demonstrate that the proposed Seg

  8. Accuracy and Utility of Deformable Image Registration in {sup 68}Ga 4D PET/CT Assessment of Pulmonary Perfusion Changes During and After Lung Radiation Therapy

    SciTech Connect

    Hardcastle, Nicholas; Hofman, Michael S.; Hicks, Rodney J.; Callahan, Jason; Kron, Tomas; MacManus, Michael P.; Ball, David L.; Jackson, Price; Siva, Shankar

    2015-09-01

    Purpose: Measuring changes in lung perfusion resulting from radiation therapy dose requires registration of the functional imaging to the radiation therapy treatment planning scan. This study investigates registration accuracy and utility for positron emission tomography (PET)/computed tomography (CT) perfusion imaging in radiation therapy for non–small cell lung cancer. Methods: {sup 68}Ga 4-dimensional PET/CT ventilation-perfusion imaging was performed before, during, and after radiation therapy for 5 patients. Rigid registration and deformable image registration (DIR) using B-splines and Demons algorithms was performed with the CT data to obtain a deformation map between the functional images and planning CT. Contour propagation accuracy and correspondence of anatomic features were used to assess registration accuracy. Wilcoxon signed-rank test was used to determine statistical significance. Changes in lung perfusion resulting from radiation therapy dose were calculated for each registration method for each patient and averaged over all patients. Results: With B-splines/Demons DIR, median distance to agreement between lung contours reduced modestly by 0.9/1.1 mm, 1.3/1.6 mm, and 1.3/1.6 mm for pretreatment, midtreatment, and posttreatment (P<.01 for all), and median Dice score between lung contours improved by 0.04/0.04, 0.05/0.05, and 0.05/0.05 for pretreatment, midtreatment, and posttreatment (P<.001 for all). Distance between anatomic features reduced with DIR by median 2.5 mm and 2.8 for pretreatment and midtreatment time points, respectively (P=.001) and 1.4 mm for posttreatment (P>.2). Poorer posttreatment results were likely caused by posttreatment pneumonitis and tumor regression. Up to 80% standardized uptake value loss in perfusion scans was observed. There was limited change in the loss in lung perfusion between registration methods; however, Demons resulted in larger interpatient variation compared with rigid and B-splines registration

  9. Thoracic dual energy CT: acquisition protocols, current applications and future developments.

    PubMed

    Ohana, M; Jeung, M Y; Labani, A; El Ghannudi, S; Roy, C

    2014-11-01

    Thanks to a simultaneous acquisition at high and low kilovoltage, dual energy computed tomography (DECT) can achieve material-based decomposition (iodine, water, calcium, etc.) and reconstruct images at different energy levels (40 to 140keV). Post-processing uses this potential to maximise iodine detection, which elicits demonstrated added value for chest imaging in acute and chronic embolic diseases (increases the quality of the examination and identifies perfusion defects), follow-up of aortic endografts and detection of contrast uptake in oncology. In CT angiography, these unique features are taken advantage of to reduce the iodine load by more than half. This review article aims to set out the physical basis for the technology, the acquisition and post-processing protocols used, its proven advantages in chest pathologies, and to present future developments. PMID:24780370

  10. Novel iterative reconstruction method with optimal dose usage for partially redundant CT-acquisition

    NASA Astrophysics Data System (ADS)

    Bruder, H.; Raupach, R.; Sunnegardh, J.; Allmendinger, T.; Klotz, E.; Stierstorfer, K.; Flohr, T.

    2015-11-01

    In CT imaging, a variety of applications exist which are strongly SNR limited. However, in some cases redundant data of the same body region provide additional quanta. Examples: in dual energy CT, the spatial resolution has to be compromised to provide good SNR for material decomposition. However, the respective spectral dataset of the same body region provides additional quanta which might be utilized to improve SNR of each spectral component. Perfusion CT is a high dose application, and dose reduction is highly desirable. However, a meaningful evaluation of perfusion parameters might be impaired by noisy time frames. On the other hand, the SNR of the average of all time frames is extremely high. In redundant CT acquisitions, multiple image datasets can be reconstructed and averaged to composite image data. These composite image data, however, might be compromised with respect to contrast resolution and/or spatial resolution and/or temporal resolution. These observations bring us to the idea of transferring high SNR of composite image data to low SNR ‘source’ image data, while maintaining their resolution. It has been shown that the noise characteristics of CT image data can be improved by iterative reconstruction (Popescu et al 2012 Book of Abstracts, 2nd CT Meeting (Salt Lake City, UT) p 148). In case of data dependent Gaussian noise it can be modelled with image-based iterative reconstruction at least in an approximate manner (Bruder et al 2011 Proc. SPIE 7961 79610J). We present a generalized update equation in image space, consisting of a linear combination of the previous update, a correction term which is constrained by the source image data, and a regularization prior, which is initialized by the composite image data. This iterative reconstruction approach we call bimodal reconstruction (BMR). Based on simulation data it is shown that BMR can improve low contrast detectability, substantially reduces the noise power and has the potential to recover

  11. Novel iterative reconstruction method with optimal dose usage for partially redundant CT-acquisition.

    PubMed

    Bruder, H; Raupach, R; Sunnegardh, J; Allmendinger, T; Klotz, E; Stierstorfer, K; Flohr, T

    2015-11-01

    In CT imaging, a variety of applications exist which are strongly SNR limited. However, in some cases redundant data of the same body region provide additional quanta. Examples in dual energy CT, the spatial resolution has to be compromised to provide good SNR for material decomposition. However, the respective spectral dataset of the same body region provides additional quanta which might be utilized to improve SNR of each spectral component. Perfusion CT is a high dose application, and dose reduction is highly desirable. However, a meaningful evaluation of perfusion parameters might be impaired by noisy time frames. On the other hand, the SNR of the average of all time frames is extremely high.In redundant CT acquisitions, multiple image datasets can be reconstructed and averaged to composite image data. These composite image data, however, might be compromised with respect to contrast resolution and/or spatial resolution and/or temporal resolution. These observations bring us to the idea of transferring high SNR of composite image data to low SNR 'source' image data, while maintaining their resolution.It has been shown that the noise characteristics of CT image data can be improved by iterative reconstruction (Popescu et al 2012 Book of Abstracts, 2nd CT Meeting (Salt Lake City, UT) p 148). In case of data dependent Gaussian noise it can be modelled with image-based iterative reconstruction at least in an approximate manner (Bruder et al 2011 Proc. SPIE 7961 79610J). We present a generalized update equation in image space, consisting of a linear combination of the previous update, a correction term which is constrained by the source image data, and a regularization prior, which is initialized by the composite image data. This iterative reconstruction approach we call bimodal reconstruction (BMR). Based on simulation data it is shown that BMR can improve low contrast detectability, substantially reduces the noise power and has the potential to recover spatial

  12. TU-C-BRD-01: Image Guided SBRT I: Multi-Modality 4D Imaging

    SciTech Connect

    Cai, J; Mageras, G; Pan, T

    2014-06-15

    Motion management is one of the critical technical challenges for radiation therapy. 4D imaging has been rapidly adopted as essential tool to assess organ motion associated with respiratory breathing. A variety of 4D imaging techniques have been developed and are currently under development based on different imaging modalities such as CT, MRI, PET, and CBCT. Each modality provides specific and complementary information about organ and tumor respiratory motion. Effective use of each different technique or combined use of different techniques can introduce a comprehensive management of tumor motion. Specifically, these techniques have afforded tremendous opportunities to better define and delineate tumor volumes, more accurately perform patient positioning, and effectively apply highly conformal therapy techniques such as IMRT and SBRT. Successful implementation requires good understanding of not only each technique, including unique features, limitations, artifacts, imaging acquisition and process, but also how to systematically apply the information obtained from different imaging modalities using proper tools such as deformable image registration. Furthermore, it is important to understand the differences in the effects of breathing variation between different imaging modalities. A comprehensive motion management strategy using multi-modality 4D imaging has shown promise in improving patient care, but at the same time faces significant challenges. This session will focuses on the current status and advances in imaging respiration-induced organ motion with different imaging modalities: 4D-CT, 4D-MRI, 4D-PET, and 4D-CBCT/DTS. Learning Objectives: Understand the need and role of multimodality 4D imaging in radiation therapy. Understand the underlying physics behind each 4D imaging technique. Recognize the advantages and limitations of each 4D imaging technique.

  13. Evaluation of the cone beam CT for internal target volume localization in lung stereotactic radiotherapy in comparison with 4D MIP images

    SciTech Connect

    Wang, Lu; Chen, Xiaoming; Lin, Mu-Han; Lin, Teh; Fan, Jiajin; Jin, Lihui; Ma, Charlie M.; Xue, Jun

    2013-11-15

    Purpose: To investigate whether the three-dimensional cone-beam CT (CBCT) is clinically equivalent to the four-dimensional computed tomography (4DCT) maximum intensity projection (MIP) reconstructed images for internal target volume (ITV) localization in image-guided lung stereotactic radiotherapy.Methods: A ball-shaped polystyrene phantom with built-in cube, sphere, and cone of known volumes was attached to a motor-driven platform, which simulates a sinusoidal movement with changeable motion amplitude and frequency. Target motion was simulated in the patient in a superior-inferior (S-I) direction with three motion periods and 2 cm peak-to-peak amplitudes. The Varian onboard Exact-Arms kV CBCT system and the GE LightSpeed four-slice CT integrated with the respiratory-position-management 4DCT scanner were used to scan the moving phantom. MIP images were generated from the 4DCT images. The clinical equivalence of the two sets of images was evaluated by comparing the extreme locations of the moving objects along the motion direction, the centroid position of the ITV, and the ITV volumes that were contoured automatically by Velocity or calculated with an imaging gradient method. The authors compared the ITV volumes determined by the above methods with those theoretically predicted by taking into account the physical object dimensions and the motion amplitudes. The extreme locations were determined by the gradient method along the S-I axis through the center of the object. The centroid positions were determined by autocenter functions. The effect of motion period on the volume sizes was also studied.Results: It was found that the extreme locations of the objects determined from the two image modalities agreed with each other satisfactorily. They were not affected by the motion period. The average difference between the two modalities in the extreme locations was 0.68% for the cube, 1.35% for the sphere, and 0.5% for the cone, respectively. The maximum difference in the

  14. SU-E-J-06: A Feasibility Study On Clinical Implementation of 4D-CBCT in Lung Cancer Treatment

    SciTech Connect

    Hu, Y; Stanford, J; Duggar, W; Ruan, C; He, R; Yang, C

    2014-06-01

    Purpose: Four-dimensional cone-beam CT (4D-CBCT) is a novel imaging technique to setup patients with pulmonary lesions in radiation therapy. This paper is to perform a feasibility study on the implementation of 4D-CBCT as image guidance for (1) SBRT and (2) Low Modulation (Low-Mod) IMRT in lung cancer treatment. Methods: Image artifacts and observers variability are evaluated by analyzing the 4D-CT QA phantom and patient 4D image data. There are two 4D-CBCT image artifacts: (1) Spatial artifact caused by the patient irregular breathing pattern will generate blurring and anatomy gap/overlap; (2) Cone beam scattering and hardening artifact will affect the image spatial and contrast resolution. The couch shift varies between 1mm to 3mm from different observers during the 4D-CBCT registration. Breath training is highly recommended to improve the respiratory regularity during CT simulation and treatment, especially for SBRT. Elekta XVI 4.5 Symmetry protocol is adopted in the patient 4DCBCT scanning and intensity-based registration. Physician adjustments on the auto-registration are involved prior to the treatment. Physician peer review on 4D-CBCT image acquisition and registration is also recommended to reduce the inter-observer variability. The average 4D-CT in reference volume coordinates is exported to MIM Vista 5.6.2 to manually fuse to the planning CT for further evaluation. Results: (1) SBRT: 4DCBCT is performed in dry-run and in each treatment fraction. Image registration and couch shift are reviewed by another physician on the 1st fraction before the treatment starts. (2) Low-Mod IMRT: 4D-CBCT is performed and peer reviewed on weekly basis. Conclusion: 4D-CBCT in SBRT dry-run can discover the ITV discrepancies caused by the low quality 4D-CT simulation. 4D-CBCT during SBRT and Low-Mod IMRT treatment provides physicians more confidence to target lung tumor and capability to evaluate inter-fractional ITV changes. More advanced 4D-CBCT scan protocol and

  15. Description of patellar movement by 3D parameters obtained from dynamic CT acquisition

    NASA Astrophysics Data System (ADS)

    de Sá Rebelo, Marina; Moreno, Ramon Alfredo; Gobbi, Riccardo Gomes; Camanho, Gilberto Luis; de Ávila, Luiz Francisco Rodrigues; Demange, Marco Kawamura; Pecora, Jose Ricardo; Gutierrez, Marco Antonio

    2014-03-01

    The patellofemoral joint is critical in the biomechanics of the knee. The patellofemoral instability is one condition that generates pain, functional impairment and often requires surgery as part of orthopedic treatment. The analysis of the patellofemoral dynamics has been performed by several medical image modalities. The clinical parameters assessed are mainly based on 2D measurements, such as the patellar tilt angle and the lateral shift among others. Besides, the acquisition protocols are mostly performed with the leg laid static at fixed angles. The use of helical multi slice CT scanner can allow the capture and display of the joint's movement performed actively by the patient. However, the orthopedic applications of this scanner have not yet been standardized or widespread. In this work we present a method to evaluate the biomechanics of the patellofemoral joint during active contraction using multi slice CT images. This approach can greatly improve the analysis of patellar instability by displaying the physiology during muscle contraction. The movement was evaluated by computing its 3D displacements and rotations from different knee angles. The first processing step registered the images in both angles based on the femuŕs position. The transformation matrix of the patella from the images was then calculated, which provided the rotations and translations performed by the patella from its position in the first image to its position in the second image. Analysis of these parameters for all frames provided real 3D information about the patellar displacement.

  16. Evaluation of spectral CT data acquisition methods via non-stochastic variance maps

    NASA Astrophysics Data System (ADS)

    Sanchez, Adrian A.; Sidky, Emil Y.; Gilat Schmidt, Taly; Pan, Xiaochuan

    2015-03-01

    Recently, photon counting detectors capable of extracting spectral information have received much attention in CT, with promise of using spectral information to construct material basis images, correct beam-hardening artifacts, or provide improved imaging of K-edge contrast agents.1, 2 In this work, we focus on the goal of constructing images of basis material maps, and investigate the feasibility of analytically computing pixel variance maps for these images, so that alternative data acquisition and reconstruction methods can be compared and evaluated with respect to their noise properties. Our approach is based on linearization of the basis material decomposition and reconstruction operations, and we therefore demonstrate the method using the ubiquitous filtered back-projection algorithm, which is linear. We then performed preliminary investigation of the method by comparing basis material variance maps for two data acquisition methods that were previously found to have different noise properties:3 two-sided bin measurements acquired from separate, independent data realizations and two-sided bin measurements acquired from a single data realization.

  17. 4-D Photoacoustic Tomography

    PubMed Central

    Xiang, Liangzhong; Wang, Bo; Ji, Lijun; Jiang, Huabei

    2013-01-01

    Photoacoustic tomography (PAT) offers three-dimensional (3D) structural and functional imaging of living biological tissue with label-free, optical absorption contrast. These attributes lend PAT imaging to a wide variety of applications in clinical medicine and preclinical research. Despite advances in live animal imaging with PAT, there is still a need for 3D imaging at centimeter depths in real-time. We report the development of four dimensional (4D) PAT, which integrates time resolutions with 3D spatial resolution, obtained using spherical arrays of ultrasonic detectors. The 4D PAT technique generates motion pictures of imaged tissue, enabling real time tracking of dynamic physiological and pathological processes at hundred micrometer-millisecond resolutions. The 4D PAT technique is used here to image needle-based drug delivery and pharmacokinetics. We also use this technique to monitor 1) fast hemodynamic changes during inter-ictal epileptic seizures and 2) temperature variations during tumor thermal therapy. PMID:23346370

  18. 4-D Photoacoustic Tomography

    NASA Astrophysics Data System (ADS)

    Xiang, Liangzhong; Wang, Bo; Ji, Lijun; Jiang, Huabei

    2013-01-01

    Photoacoustic tomography (PAT) offers three-dimensional (3D) structural and functional imaging of living biological tissue with label-free, optical absorption contrast. These attributes lend PAT imaging to a wide variety of applications in clinical medicine and preclinical research. Despite advances in live animal imaging with PAT, there is still a need for 3D imaging at centimeter depths in real-time. We report the development of four dimensional (4D) PAT, which integrates time resolutions with 3D spatial resolution, obtained using spherical arrays of ultrasonic detectors. The 4D PAT technique generates motion pictures of imaged tissue, enabling real time tracking of dynamic physiological and pathological processes at hundred micrometer-millisecond resolutions. The 4D PAT technique is used here to image needle-based drug delivery and pharmacokinetics. We also use this technique to monitor 1) fast hemodynamic changes during inter-ictal epileptic seizures and 2) temperature variations during tumor thermal therapy.

  19. Task-driven image acquisition and reconstruction in cone-beam CT

    NASA Astrophysics Data System (ADS)

    Gang, Grace J.; Webster Stayman, J.; Ehtiati, Tina; Siewerdsen, Jeffrey H.

    2015-04-01

    This work introduces a task-driven imaging framework that incorporates a mathematical definition of the imaging task, a model of the imaging system, and a patient-specific anatomical model to prospectively design image acquisition and reconstruction techniques to optimize task performance. The framework is applied to joint optimization of tube current modulation, view-dependent reconstruction kernel, and orbital tilt in cone-beam CT. The system model considers a cone-beam CT system incorporating a flat-panel detector and 3D filtered backprojection and accurately describes the spatially varying noise and resolution over a wide range of imaging parameters in the presence of a realistic anatomical model. Task-based detectability index (d‧) is incorporated as the objective function in a task-driven optimization of image acquisition and reconstruction techniques. The orbital tilt was optimized through an exhaustive search across tilt angles ranging ±30°. For each tilt angle, the view-dependent tube current and reconstruction kernel (i.e. the modulation profiles) that maximized detectability were identified via an alternating optimization. The task-driven approach was compared with conventional unmodulated and automatic exposure control (AEC) strategies for a variety of imaging tasks and anthropomorphic phantoms. The task-driven strategy outperformed the unmodulated and AEC cases for all tasks. For example, d‧ for a sphere detection task in a head phantom was improved by 30% compared to the unmodulated case by using smoother kernels for noisy views and distributing mAs across less noisy views (at fixed total mAs) in a manner that was beneficial to task performance. Similarly for detection of a line-pair pattern, the task-driven approach increased d‧ by 80% compared to no modulation by means of view-dependent mA and kernel selection that yields modulation transfer function and noise-power spectrum optimal to the task. Optimization of orbital tilt identified the

  20. Task-driven image acquisition and reconstruction in cone-beam CT

    PubMed Central

    Gang, Grace J.; Stayman, J. Webster; Ehtiati, Tina; Siewerdsen, Jeffrey H.

    2015-01-01

    This work introduces a task-driven imaging framework that incorporates a mathematical definition of the imaging task, a model of the imaging system, and a patient-specific anatomical model to prospectively design image acquisition and reconstruction techniques to optimize task performance. The framework is applied to joint optimization of tube current modulation, view-dependent reconstruction kernel, and orbital tilt in cone-beam CT. The system model considers a cone-beam CT system incorporating a flat-panel detector and 3D filtered backprojection and accurately describes the spatially varying noise and resolution over a wide range of imaging parameters and in the presence of a realistic anatomical model. Task-based detectability index (d') is incorporated as the objective function in a task-driven optimization of image acquisition and reconstruction techniques. The orbital tilt was optimized through an exhaustive search across tilt angles ranging ±30°. For each tilt angle, the view-dependent tube current and reconstruction kernel (i.e., the modulation profiles) that maximized detectability were identified via an alternating optimization. The task-driven approach was compared with conventional unmodulated and automatic exposure control (AEC) strategies for a variety of imaging tasks and anthropomorphic phantoms. The task-driven strategy outperformed the unmodulated and AEC cases for all tasks. For example, d' for a sphere detection task in a head phantom was improved by 30% compared to the unmodulated case by using smoother kernels for noisy views and distributing mAs across less noisy views (at fixed total mAs) in a manner that was beneficial to task performance. Similarly for detection of a line-pair pattern, the task-driven approach increased d' by 80% compared to no modulation by means of view-dependent mA and kernel selection that yields modulation transfer function and noise-power spectrum optimal to the task. Optimization of orbital tilt identified the

  1. 4D SPECT/CT acquisition for 3D dose calculation and dose planning in (177)Lu-peptide receptor radionuclide therapy: applications for clinical routine.

    PubMed

    Kairemo, Kalevi; Kangasmäki, Aki

    2013-01-01

    Molecular radiotherapy combines the potential of a specific tracer (vector) targeting tumor cells with local radiotoxicity. Designing a specific tumor-targeting/killing combination is a tailoring process. Radionuclides with imaging capacity serve best in the selection of the targeting molecule. The potential of targeted therapy with radiolabeled peptides has been reported in many conditions; peptide receptor radionuclide therapy (PRRT) is already part of Scandinavian guidelines for treating neuroendocrine tumors. Lu-177- and Y-90-labeled somatostatin analogs, including DOTATOC, DOTANOC, and DOTATATE, are most the commonly used and have turned out to be effective. For routine use, an efficient, rapid, and reliable dose calculation tool is needed. In this chapter we describe how serial pre- and posttherapeutic scans can be used for dose calculation and for predicting therapy doses. Our software for radionuclide dose calculation is a three-dimensional, voxel-based system. The 3D dose calculation requires coregistered SPECT image sets from several time points after infusion to reconstruct time-activity curves for each voxel. Image registration is done directly by SPECT image registration using the first time point as a target. From the time-activity curves, initial activity and total half-life maps are calculated to produce a cumulated activity map. The cumulated activity map is then convoluted with a voxel-dose kernel to obtain a 3D dose map. We performed dose calculations similarly for both therapeutic and preplanning images. Preplanning dose was extrapolated to predict therapy dose using the ratio of administered activities. Our 3D dose calculation results are also compared with those of OLINDA. Our preliminary results indicate that dose planning using pretherapeutic scanning can predict critical organ and tumor doses. In some cases, the dose planning prediction resulted in slight, and slightly dose-dependent, overestimation of final therapy dose. Real tumor dose was similar in both pretherapeutic and posttherapeutic scans using our software. The OLINDA software and our program gave similar normal organ doses, whereas tumor doses could be calculated in a more detailed manner using the 3D program. PMID:22918781

  2. Novel ultrahigh resolution data acquisition and image reconstruction for multi-detector row CT

    SciTech Connect

    Flohr, T. G.; Stierstorfer, K.; Suess, C.; Schmidt, B.; Primak, A. N.; McCollough, C. H.

    2007-05-15

    We present and evaluate a special ultrahigh resolution mode providing considerably enhanced spatial resolution both in the scan plane and in the z-axis direction for a routine medical multi-detector row computed tomography (CT) system. Data acquisition is performed by using a flying focal spot both in the scan plane and in the z-axis direction in combination with tantalum grids that are inserted in front of the multi-row detector to reduce the aperture of the detector elements both in-plane and in the z-axis direction. The dose utilization of the system for standard applications is not affected, since the grids are moved into place only when needed and are removed for standard scanning. By means of this technique, image slices with a nominal section width of 0.4 mm (measured full width at half maximum=0.45 mm) can be reconstructed in spiral mode on a CT system with a detector configuration of 32x0.6 mm. The measured 2% value of the in-plane modulation transfer function (MTF) is 20.4 lp/cm, the measured 2% value of the longitudinal (z axis) MTF is 21.5 lp/cm. In a resolution phantom with metal line pair test patterns, spatial resolution of 20 lp/cm can be demonstrated both in the scan plane and along the z axis. This corresponds to an object size of 0.25 mm that can be resolved. The new mode is intended for ultrahigh resolution bone imaging, in particular for wrists, joints, and inner ear studies, where a higher level of image noise due to the reduced aperture is an acceptable trade-off for the clinical benefit brought about by the improved spatial resolution.

  3. EFFECT ON PERFUSION VALUES OF SAMPLING INTERVAL OF CT PERFUSION ACQUISITIONS IN NEUROENDOCRINE LIVER METASTASES AND NORMAL LIVER

    PubMed Central

    Ng, Chaan S.; Hobbs, Brian P.; Wei, Wei; Anderson, Ella F.; Herron, Delise H.; Yao, James C.; Chandler, Adam G.

    2014-01-01

    Objective To assess the effects of sampling interval (SI) of CT perfusion acquisitions on CT perfusion values in normal liver and liver metastases from neuroendocrine tumors. Methods CT perfusion in 16 patients with neuroendocrine liver metastases were analyzed by distributed parameter modeling to yield tissue blood flow, blood volume, mean transit time, permeability, and hepatic arterial fraction, for tumor and normal liver. CT perfusion values for the reference sampling interval of 0.5s (SI0.5) were compared with those of SI datasets of 1s, 2s, 3s and 4s, using mixed-effects model analyses. Results Increases in SI beyond 1s were associated with significant and increasing departures of CT perfusion parameters from reference values at SI0.5 (p≤0.0009). CT perfusion values deviated from reference with increasing uncertainty with increasing SIs. Findings for normal liver were concordant. Conclusion Increasing SIs beyond 1s yield significantly different CT perfusion parameter values compared to reference values at SI0.5. PMID:25626401

  4. Three dimensional dose distribution comparison of simple and complex acquisition trajectories in dedicated breast CT

    PubMed Central

    Shah, Jainil P.; Mann, Steve D.; McKinley, Randolph L.; Tornai, Martin P.

    2015-01-01

    Purpose: A novel breast CT system capable of arbitrary 3D trajectories has been developed to address cone beam sampling insufficiency as well as to image further into the patient’s chest wall. The purpose of this study was to characterize any trajectory-related differences in 3D x-ray dose distribution in a pendant target when imaged with different orbits. Methods: Two acquisition trajectories were evaluated: circular azimuthal (no-tilt) and sinusoidal (saddle) orbit with ±15° tilts around a pendant breast, using Monte Carlo simulations as well as physical measurements. Simulations were performed with tungsten (W) filtration of a W-anode source; the simulated source flux was normalized to the measured exposure of a W-anode source. A water-filled cylindrical phantom was divided into 1 cm3 voxels, and the cumulative energy deposited was tracked in each voxel. Energy deposited per voxel was converted to dose, yielding the 3D distributed dose volumes. Additionally, three cylindrical phantoms of different diameters (10, 12.5, and 15 cm) and an anthropomorphic breast phantom, initially filled with water (mimicking pure fibroglandular tissue) and then with a 75% methanol-25% water mixture (mimicking 50–50 fibroglandular-adipose tissues), were used to simulate the pendant breast geometry and scanned on the physical system. Ionization chamber calibrated radiochromic film was used to determine the dose delivered in a 2D plane through the center of the volume for a fully 3D CT scan using the different orbits. Results: Measured experimental results for the same exposure indicated that the mean dose measured throughout the central slice for different diameters ranged from 3.93 to 5.28 mGy, with the lowest average dose measured on the largest cylinder with water mimicking a homogeneously fibroglandular breast. These results align well with the cylinder phantom Monte Carlo studies which also showed a marginal difference in dose delivered by a saddle trajectory in the

  5. Novel iterative reconstruction method for optimal dose usage in redundant CT - acquisitions

    NASA Astrophysics Data System (ADS)

    Bruder, H.; Raupach, R.; Allmendinger, T.; Kappler, S.; Sunnegardh, J.; Stierstorfer, K.; Flohr, T.

    2014-03-01

    In CT imaging, a variety of applications exist where reconstructions are SNR and/or resolution limited. However, if the measured data provide redundant information, composite image data with high SNR can be computed. Generally, these composite image volumes will compromise spectral information and/or spatial resolution and/or temporal resolution. This brings us to the idea of transferring the high SNR of the composite image data to low SNR (but high resolution) `source' image data. It was shown that the SNR of CT image data can be improved using iterative reconstruction [1] .We present a novel iterative reconstruction method enabling optimal dose usage of redundant CT measurements of the same body region. The generalized update equation is formulated in image space without further referring to raw data after initial reconstruction of source and composite image data. The update equation consists of a linear combination of the previous update, a correction term constrained by the source data, and a regularization prior initialized by the composite data. The efficiency of the method is demonstrated for different applications: (i) Spectral imaging: we have analysed material decomposition data from dual energy data of our photon counting prototype scanner: the material images can be significantly improved transferring the good noise statistics of the 20 keV threshold image data to each of the material images. (ii) Multi-phase liver imaging: Reconstructions of multi-phase liver data can be optimized by utilizing the noise statistics of combined data from all measured phases (iii) Helical reconstruction with optimized temporal resolution: splitting up reconstruction of redundant helical acquisition data into a short scan reconstruction with Tam window optimizes the temporal resolution The reconstruction of full helical data is then used to optimize the SNR. (iv) Cardiac imaging: the optimal phase image (`best phase') can be improved by transferring all applied over

  6. [Usefulness of Determining Acquisition Time by True Count Rate Measurement Method for Delivery 18F-FDG PET/CT].

    PubMed

    Miura, Shota; Odashima, Satoshi

    2016-03-01

    A stable quality of delivery 18F-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) requires suitable acquisition time, which can be obtained from an accurate true count of 18F-FDG. However, the true count is influenced by body mass index (BMI) and attenuation of 18F-FDG. In order to remove these influences, we have developed a new method (actual measurement method) to measure the actual true count rate based on sub-pubic thigh, which allows us to calculate a suitable acquisition time. In this study, we aimed to verify the acquisition count through our new method in terms of two categories: (1) the accuracy of acquisition count and (2) evaluation of clinical images using physical index. Our actual measurement method was designed to obtain suitable acquisition time through the following procedure. A true count rate of sub-pubic thigh was measured through detector of PET, and used as a standard true count rate. Finally, the obtained standard count rate was processed to acquisition time. This method was retrospectively applied to 150 patients, receiving 18F-FDG administration from 109.7 to 336.8 MBq, and whose body weight ranged from 37 to 95.4 kg. The accuracy of true count was evaluated by comparing relationships of true count, relative to BMI or to administered dose of 18F-FDG. The PET/CT images obtained by our actual measurement method were assessed using physical index. Our new method resulted in accurate true count, which was not influenced by either BMI or administered dose of 18F-FDG, as well as satisfied PET/CT images with recommended criteria of physical index in all patients. PMID:27000670

  7. Constrained reconstructions for 4D intervention guidance

    NASA Astrophysics Data System (ADS)

    Kuntz, J.; Flach, B.; Kueres, R.; Semmler, W.; Kachelrieß, M.; Bartling, S.

    2013-05-01

    Image-guided interventions are an increasingly important part of clinical minimally invasive procedures. However, up to now they cannot be performed under 4D (3D + time) guidance due to the exceedingly high x-ray dose. In this work we investigate the applicability of compressed sensing reconstructions for highly undersampled CT datasets combined with the incorporation of prior images in order to yield low dose 4D intervention guidance. We present a new reconstruction scheme prior image dynamic interventional CT (PrIDICT) that accounts for specific image features in intervention guidance and compare it to PICCS and ASD-POCS. The optimal parameters for the dose per projection and the numbers of projections per reconstruction are determined in phantom simulations and measurements. In vivo experiments in six pigs are performed in a cone-beam CT; measured doses are compared to current gold-standard intervention guidance represented by a clinical fluoroscopy system. Phantom studies show maximum image quality for identical overall doses in the range of 14 to 21 projections per reconstruction. In vivo studies reveal that interventional materials can be followed in 4D visualization and that PrIDICT, compared to PICCS and ASD-POCS, shows superior reconstruction results and fewer artifacts in the periphery with dose in the order of biplane fluoroscopy. These results suggest that 4D intervention guidance can be realized with today’s flat detector and gantry systems using the herein presented reconstruction scheme.

  8. Lung deformation estimation and four-dimensional CT lung reconstruction.

    PubMed

    Xu, Sheng; Taylor, Russell H; Fichtinger, Gabor; Cleary, Kevin

    2005-01-01

    Four-dimensional (4D) computed tomography (CT) image acquisition is a useful technique in radiation treatment planning and interventional radiology in that it can account for respiratory motion of lungs. Current 4D lung reconstruction techniques have limitations in either spatial or temporal resolution. In addition, most of these techniques rely on auxiliary surrogates to relate the time of CT scan to the patient's respiratory phase. In this paper, we propose a novel 4D CT lung reconstruction and deformation estimation algorithm. Our algorithm is purely image based. The algorithm can reconstruct high quality 4D images even if the original images are acquired under irregular respiratory motion. The algorithm is validated using synthetic 4D lung data. Experimental results from a swine study data are also presented. PMID:16685974

  9. Automatic estimation of detector radial position for contoured SPECT acquisition using CT images on a SPECT/CT system.

    PubMed

    Liu, Ruijie Rachel; Erwin, William D

    2006-08-01

    An algorithm was developed to estimate noncircular orbit (NCO) single-photon emission computed tomography (SPECT) detector radius on a SPECT/CT imaging system using the CT images, for incorporation into collimator resolution modeling for iterative SPECT reconstruction. Simulated male abdominal (arms up), male head and neck (arms down) and female chest (arms down) anthropomorphic phantom, and ten patient, medium-energy SPECT/CT scans were acquired on a hybrid imaging system. The algorithm simulated inward SPECT detector radial motion and object contour detection at each projection angle, employing the calculated average CT image and a fixed Hounsfield unit (HU) threshold. Calculated radii were compared to the observed true radii, and optimal CT threshold values, corresponding to patient bed and clothing surfaces, were found to be between -970 and -950 HU. The algorithm was constrained by the 45 cm CT field-of-view (FOV), which limited the detected radii to < or = 22.5 cm and led to occasional radius underestimation in the case of object truncation by CT. Two methods incorporating the algorithm were implemented: physical model (PM) and best fit (BF). The PM method computed an offset that produced maximum overlap of calculated and true radii for the phantom scans, and applied that offset as a calculated-to-true radius transformation. For the BF method, the calculated-to-true radius transformation was based upon a linear regression between calculated and true radii. For the PM method, a fixed offset of +2.75 cm provided maximum calculated-to-true radius overlap for the phantom study, which accounted for the camera system's object contour detect sensor surface-to-detector face distance. For the BF method, a linear regression of true versus calculated radius from a reference patient scan was used as a calculated-to-true radius transform. Both methods were applied to ten patient scans. For -970 and -950 HU thresholds, the combined overall average root-mean-square (rms

  10. Automatic estimation of detector radial position for contoured SPECT acquisition using CT images on a SPECT/CT system

    SciTech Connect

    Liu Ruijie Rachel; Erwin, William D.

    2006-08-15

    An algorithm was developed to estimate noncircular orbit (NCO) single-photon emission computed tomography (SPECT) detector radius on a SPECT/CT imaging system using the CT images, for incorporation into collimator resolution modeling for iterative SPECT reconstruction. Simulated male abdominal (arms up), male head and neck (arms down) and female chest (arms down) anthropomorphic phantom, and ten patient, medium-energy SPECT/CT scans were acquired on a hybrid imaging system. The algorithm simulated inward SPECT detector radial motion and object contour detection at each projection angle, employing the calculated average CT image and a fixed Hounsfield unit (HU) threshold. Calculated radii were compared to the observed true radii, and optimal CT threshold values, corresponding to patient bed and clothing surfaces, were found to be between -970 and -950 HU. The algorithm was constrained by the 45 cm CT field-of-view (FOV), which limited the detected radii to {<=}22.5 cm and led to occasional radius underestimation in the case of object truncation by CT. Two methods incorporating the algorithm were implemented: physical model (PM) and best fit (BF). The PM method computed an offset that produced maximum overlap of calculated and true radii for the phantom scans, and applied that offset as a calculated-to-true radius transformation. For the BF method, the calculated-to-true radius transformation was based upon a linear regression between calculated and true radii. For the PM method, a fixed offset of +2.75 cm provided maximum calculated-to-true radius overlap for the phantom study, which accounted for the camera system's object contour detect sensor surface-to-detector face distance. For the BF method, a linear regression of true versus calculated radius from a reference patient scan was used as a calculated-to-true radius transform. Both methods were applied to ten patient scans. For -970 and -950 HU thresholds, the combined overall average root-mean-square (rms) error

  11. Creation of 4D imaging data using open source image registration software

    NASA Astrophysics Data System (ADS)

    Wong, Kenneth H.; Ibanez, Luis; Popa, Teo; Cleary, Kevin

    2006-03-01

    4D images (3 spatial dimensions plus time) using CT or MRI will play a key role in radiation medicine as techniques for respiratory motion compensation become more widely available. Advance knowledge of the motion of a tumor and its surrounding anatomy will allow the creation of highly conformal dose distributions in organs such as the lung, liver, and pancreas. However, many of the current investigations into 4D imaging rely on synchronizing the image acquisition with an external respiratory signal such as skin motion, tidal flow, or lung volume, which typically requires specialized hardware and modifications to the scanner. We propose a novel method for 4D image acquisition that does not require any specific gating equipment and is based solely on open source image registration algorithms. Specifically, we use the Insight Toolkit (ITK) to compute the normalized mutual information (NMI) between images taken at different times and use that value as an index of respiratory phase. This method has the advantages of (1) being able to be implemented without any hardware modification to the scanner, and (2) basing the respiratory phase on changes in internal anatomy rather than external signal. We have demonstrated the capabilities of this method with CT fluoroscopy data acquired from a swine model.

  12. CT acquisition technique and quantitative analysis of the lung parenchyma: variability and corrections

    NASA Astrophysics Data System (ADS)

    Zheng, Bin; Leader, J. K.; Coxson, Harvey O.; Scuirba, Frank C.; Fuhrman, Carl R.; Balkan, Arzu; Weissfeld, Joel L.; Maitz, Glenn S.; Gur, David

    2006-03-01

    The fraction of lung voxels below a pixel value "cut-off" has been correlated with pathologic estimates of emphysema. We performed a "standard" quantitative CT (QCT) lung analysis using a -950 HU cut-off to determine the volume fraction of emphysema (below the cut-off) and a "corrected" QCT analysis after removing small group (5 and 10 pixels) of connected pixels ("blobs") below the cut-off. CT examinations two dataset of 15 subjects each with a range of visible emphysema and pulmonary obstruction were acquired at "low-dose and conventional dose reconstructed using a high-spatial frequency kernel at 2.5 mm section thickness for the same subject. The "blob" size (i.e., connected-pixels) removed was inversely related to the computed fraction of emphysema. The slopes of emphysema fraction versus blob size were 0.013, 0.009, and 0.005 for subjects with both no emphysema and no pulmonary obstruction, moderate emphysema and pulmonary obstruction, and severe emphysema and severe pulmonary obstruction, respectively. The slopes of emphysema fraction versus blob size were 0.008 and 0.006 for low-dose and conventional CT examinations, respectively. The small blobs of pixels removed are most likely CT image artifacts and do not represent actual emphysema. The magnitude of the blob correction was appropriately associated with COPD severity. The blob correction appears to be applicable to QCT analysis in low-dose and conventional CT exams.

  13. Simulation of four-dimensional CT images from deformable registration between inhale and exhale breath-hold CT scans

    SciTech Connect

    Sarrut, David; Boldea, Vlad; Miguet, Serge; Ginestet, Chantal

    2006-03-15

    feasible. This can lower the dose needed for 4-D CT acquisitions or can help to correct 4-D acquisition artifacts. The 4-D CT model can be used to propagate contours, to compute a 4-D dose map, or to simulate CT acquisitions with an irregular breathing signal. It could serve as a basis for 4-D radiation therapy planning. Further work is needed to make the simulation more realistic by taking into account hysteresis and more complex voxel trajectories.

  14. Experimental investigation of irregular motion impact on 4D PET-based particle therapy monitoring.

    PubMed

    Tian, Y; Stützer, K; Enghardt, W; Priegnitz, M; Helmbrecht, S; Bert, C; Fiedler, F

    2016-01-21

    Particle therapy positron emission tomography (PT-PET) is an in vivo and non-invasive imaging technique to monitor treatment delivery in particle therapy. The inevitable patient respiratory motion during irradiation causes artefacts and inaccurate activity distribution in PET images. Four-dimensional (4D) maximum likelihood expectation maximisation (4D MLEM) allows for a compensation of these effects, but has up to now been restricted to regular motion for PT-PET investigations. However, intra-fractional motion during treatment might differ from that during acquisition of the 4D-planning CT (e.g. amplitude variation, baseline drift) and therefore might induce inaccurate 4D PET reconstruction results. This study investigates the impact of different irregular analytical one-dimensional (1D) motion patterns on PT-PET imaging by means of experiments with a radioactive source and irradiated moving phantoms. Three sorting methods, namely phase sorting, equal amplitude sorting and event-based amplitude sorting, were applied to manage the PET list-mode data. The influence of these sorting methods on the motion compensating algorithm has been analysed. The event-based amplitude sorting showed a superior performance and it is applicable for irregular motions with ⩽ 4 mm amplitude elongation and drift. For motion with 10 mm baseline drift, the normalised root mean square error was as high as 10.5% and a 10 mm range deviation was observed. PMID:26733104

  15. Experimental investigation of irregular motion impact on 4D PET-based particle therapy monitoring

    NASA Astrophysics Data System (ADS)

    Tian, Y.; Stützer, K.; Enghardt, W.; Priegnitz, M.; Helmbrecht, S.; Bert, C.; Fiedler, F.

    2016-01-01

    Particle therapy positron emission tomography (PT-PET) is an in vivo and non-invasive imaging technique to monitor treatment delivery in particle therapy. The inevitable patient respiratory motion during irradiation causes artefacts and inaccurate activity distribution in PET images. Four-dimensional (4D) maximum likelihood expectation maximisation (4D MLEM) allows for a compensation of these effects, but has up to now been restricted to regular motion for PT-PET investigations. However, intra-fractional motion during treatment might differ from that during acquisition of the 4D-planning CT (e.g. amplitude variation, baseline drift) and therefore might induce inaccurate 4D PET reconstruction results. This study investigates the impact of different irregular analytical one-dimensional (1D) motion patterns on PT-PET imaging by means of experiments with a radioactive source and irradiated moving phantoms. Three sorting methods, namely phase sorting, equal amplitude sorting and event-based amplitude sorting, were applied to manage the PET list-mode data. The influence of these sorting methods on the motion compensating algorithm has been analysed. The event-based amplitude sorting showed a superior performance and it is applicable for irregular motions with  ⩽4 mm amplitude elongation and drift. For motion with 10 mm baseline drift, the normalised root mean square error was as high as 10.5% and a 10 mm range deviation was observed.

  16. Quantification of airway morphometry: the effect of CT acquisition and reconstruction parameters

    NASA Astrophysics Data System (ADS)

    Leader, J. Ken; Zheng, Bin; Sciurba, Frank C.; Coxson, Harvey O.; Fuhrman, Carl R.; McMurray, Jessica M.; Park, Sang C.; Maitz, Glenn S.; Gur, David

    2007-03-01

    This study measured the accuracy of our airway quantification scheme using phantoms airway under different CT protocols. Airway remodeling is associated with several thoracic diseases (e.g., chronic bronchitis, asthma, and bronchiectasis), and, therefore, quantification of airway remodeling may have wide clinical application. Our scheme assigns pixels partial membership in the airway wall and lumen based on the pixel's HU value, which is intended to account for partial volume averaging inherent in CT image reconstruction. Twenty-four phantom airways with an outer diameter from 2.6 to 14.0 mm and wall thicknesses from 0.5 to 2.0 mm were analyzed. The absolute differences between measurements supplied by the manufacture and computed from CT images acquired at 40 mAs and reconstructed at 1.25 mm thickness using GE's "soft" and "lung" reconstruction kernels for lumen area ranged from 1.4% to 49.3% and 0.4% to 33.0%, respectively, and for wall area ranged from 0.3% to 118.0% and 2.1 to 92.9%, respectively. Accuracy typically improved as the kernel's spatial frequency increased. Airways whose wall thickness was close to the pixels dimensions were challenging to quantify. The partial membership assignment of our airway quantification accurately computed airway morphometry across a range of phantom airway sizes.

  17. An image acquisition and registration strategy for the fusion of hyperpolarized helium-3 MRI and x-ray CT images of the lung

    NASA Astrophysics Data System (ADS)

    Ireland, Rob H.; Woodhouse, Neil; Hoggard, Nigel; Swinscoe, James A.; Foran, Bernadette H.; Hatton, Matthew Q.; Wild, Jim M.

    2008-11-01

    The purpose of this ethics committee approved prospective study was to evaluate an image acquisition and registration protocol for hyperpolarized helium-3 magnetic resonance imaging (3He-MRI) and x-ray computed tomography. Nine patients with non-small cell lung cancer (NSCLC) gave written informed consent to undergo a free-breathing CT, an inspiration breath-hold CT and a 3D ventilation 3He-MRI in CT position using an elliptical birdcage radiofrequency (RF) body coil. 3He-MRI to CT image fusion was performed using a rigid registration algorithm which was assessed by two observers using anatomical landmarks and a percentage volume overlap coefficient. Registration of 3He-MRI to breath-hold CT was more accurate than to free-breathing CT; overlap 82.9 ± 4.2% versus 59.8 ± 9.0% (p < 0.001) and mean landmark error 0.75 ± 0.24 cm versus 1.25 ± 0.60 cm (p = 0.002). Image registration is significantly improved by using an imaging protocol that enables both 3He-MRI and CT to be acquired with similar breath holds and body position through the use of a birdcage 3He-MRI body RF coil and an inspiration breath-hold CT. Fusion of 3He-MRI to CT may be useful for the assessment of patients with lung diseases.

  18. Localization of acoustic emission sources in tensile and ct specimens using a broadband acquisition technique.

    PubMed

    Fleischmann, P; Rouby, D; Malaprade, G; Lanchon, I

    1981-11-01

    The acoustic emission sources in a conventional cylindrical tensile test sample of short transversely-cut carbon manganese steel are localized. There is not always a good correlation between the localization of the first signals and the zone which eventually fractures. During the Lüder's plateau, the ae signals are emitted in the deformation band and, in the hardening range, there is no significant ae in the gauge length of the sample. In ct samples precracked by fatigue, the signals are due to the growth of the plastic zone around the crack tip, and the plastic zone size, measured by source localization, agrees with those provided by models derived from fracture mechanics. PMID:7292774

  19. Reducing the formation of image artifacts during spectroscopic micro-CT acquisitions

    NASA Astrophysics Data System (ADS)

    Zuber, Marcus; Koenig, Thomas; Hussain, Rubaiya; Hamann, Elias; Ballabriga, Rafael; Campbell, Michael; Fauler, Alex; Fiederle, Michael; Baumbach, Tilo

    2015-03-01

    Spectroscopic micro-computed tomography using photon counting detectors is a technology that promises to deliver material-specific images in pre-clinical research. Inherent to such applications is the need for a high spatial resolution, which can only be achieved with small focal spot sizes in the micrometer range. This limits the achievable x-ray fluxes and implies long acquisitions easily exceeding one hour, during which it is paramount to maintain a constant detector response. Given that photon-counting detectors are delicate systems, with each pixel hosting advanced analog and digital circuitry, this can represent a challenging task. In this contribution, we illustrate our findings on how to reduce image artifacts in computed tomography reconstructions under these conditions, using a Medipix3RX detector featuring a cadmium telluride sensor. We find that maintaining a constant temperature is a prerequisite to guarantee energy threshold stability. More importantly, we identify varying sensor leakage currents as a significant source to artifact formation. We show that these leakage currents can render the corresponding images unusable if the ambient temperature fluctuates, as caused by an air conditioning, for example. We conclude with demonstrating the necessity of an adjustable leakage current compensation.

  20. Effect of Extended CT Perfusion Acquisition Time on Ischemic Core and Penumbra Volume Estimation in Patients with Acute Ischemic Stroke due to a Large Vessel Occlusion

    PubMed Central

    Borst, Jordi; Marquering, Henk A.; Beenen, Ludo F. M.; Berkhemer, Olvert A.; Dankbaar, Jan Willem; Riordan, Alan J.; Majoie, Charles B. L. M.

    2015-01-01

    Background and Purpose It has been suggested that CT Perfusion acquisition times <60 seconds are too short to capture the complete in and out-wash of contrast in the tissue, resulting in incomplete time attenuation curves. Yet, these short acquisitions times are not uncommon in clinical practice. The purpose of this study was to investigate the occurrence of time attenuation curve truncation in 48 seconds CT Perfusion acquisition and to quantify its effect on ischemic core and penumbra estimation in patients with acute ischemic stroke due to a proximal intracranial arterial occlusion of the anterior circulation. Materials and Methods We analyzed CT Perfusion data with 48 seconds and extended acquisition times, assuring full time attenuation curves, of 36 patients. Time attenuation curves were classified as complete or truncated. Ischemic core and penumbra volumes resulting from both data sets were compared by median paired differences and interquartile ranges. Controlled experiments were performed using a digital CT Perfusion phantom to investigate the effect of time attenuation curve truncation on ischemic core and penumbra estimation. Results In 48 seconds acquisition data, truncation was observed in 24 (67%) cases for the time attenuation curves in the ischemic core, in 2 cases for the arterial input function and in 5 cases for the venous output function. Analysis of extended data resulted in smaller ischemic cores and larger penumbras with a median difference of 13.2 (IQR: 4.3–26.0)ml (P<0.001) and; 12.4 (IQR: 4.1–25.7)ml (P<0.001), respectively. The phantom data showed increasing ischemic core overestimation with increasing tissue time attenuation curve truncation. Conclusions Truncation is common in patients with large vessel occlusion and results in repartitioning of the area of hypoperfusion into larger ischemic core and smaller penumbra estimations. Phantom experiments confirmed that truncation results in overestimation of the ischemic core. PMID

  1. 4D offline PET-based treatment verification in scanned ion beam therapy: a phantom study

    NASA Astrophysics Data System (ADS)

    Kurz, Christopher; Bauer, Julia; Unholtz, Daniel; Richter, Daniel; Stützer, Kristin; Bert, Christoph; Parodi, Katia

    2015-08-01

    At the Heidelberg Ion-Beam Therapy Center, patient irradiation with scanned proton and carbon ion beams is verified by offline positron emission tomography (PET) imaging: the {β+} -activity measured within the patient is compared to a prediction calculated on the basis of the treatment planning data in order to identify potential delivery errors. Currently, this monitoring technique is limited to the treatment of static target structures. However, intra-fractional organ motion imposes considerable additional challenges to scanned ion beam radiotherapy. In this work, the feasibility and potential of time-resolved (4D) offline PET-based treatment verification with a commercial full-ring PET/CT (x-ray computed tomography) device are investigated for the first time, based on an experimental campaign with moving phantoms. Motion was monitored during the gated beam delivery as well as the subsequent PET acquisition and was taken into account in the corresponding 4D Monte-Carlo simulations and data evaluation. Under the given experimental conditions, millimeter agreement between the prediction and measurement was found. Dosimetric consequences due to the phantom motion could be reliably identified. The agreement between PET measurement and prediction in the presence of motion was found to be similar as in static reference measurements, thus demonstrating the potential of 4D PET-based treatment verification for future clinical applications.

  2. R4D on Ramp

    NASA Technical Reports Server (NTRS)

    1956-01-01

    This Photograph taken in 1956 shows the first of three R4D Skytrain aircraft on the ramp behind the NACA High-Speed Flight Station. Note the designation 'United States NACA' on the side of the aircraft. NACA stood for the National Advisory Committee for Aeronautics, which evolved into the National Aeronautics and Space Administration (NASA) in 1958. The R4D Skytrain was one of the early workhorses for NACA and NASA at Edwards Air Force Base, California, from 1952 to 1984. Designated the R4D by the U.S. Navy, the aircraft was called the C-47 by the U.S. Army and U.S. Air Force and the DC-3 by its builder, Douglas Aircraft. Nearly everyone called it the 'Gooney Bird.' In 1962, Congress consolidated the military-service designations and called all of them the C-47. After that date, the R4D at NASA's Flight Research Center (itself redesignated the Dryden Flight Research Center in 1976) was properly called a C-47. Over the 32 years it was used at Edwards, three different R4D/C-47s were used to shuttle personnel and equipment between NACA/NASA Centers and test locations throughout the country and for other purposes. One purpose was landing on 'dry' lakebeds used as alternate landing sites for the X-15, to determine whether their surfaces were hard (dry) enough for the X-15 to land on in case an emergency occurred after its launch and before it could reach Rogers Dry Lake at Edwards Air Force Base. The R4D/C-47 served a variety of needs, including serving as the first air-tow vehicle for the M2-F1 lifting body (which was built of mahogany plywood). The C-47 (as it was then called) was used for 77 tows before the M2-F1 was retired for more advanced lifting bodies that were dropped from the NASA B-52 'Mothership.' The R4D also served as a research aircraft. It was used to conduct early research on wing-tip-vortex flow visualization as well as checking out the NASA Uplink Control System. The first Gooney Bird was at the NACA High-Speed Flight Research Station (now the Dryden

  3. Post-acquisition small-animal respiratory gated imaging using micro cone-beam CT

    NASA Astrophysics Data System (ADS)

    Hu, Jicun; Haworth, Steven T.; Molthen, Robert C.; Dawson, Christopher A.

    2004-04-01

    On many occasions, it is desirable to image lungs in vivo to perform a pulmonary physiology study. Since the lungs are moving, gating with respect to the ventilatory phase has to be performed in order to minimize motion artifacts. Gating can be done in real time, similar to cardiac imaging in clinical applications, however, there are technical problems that have lead us to investigate different approaches. The problems include breath-to-breath inconsistencies in tidal volume, which makes the precise detection of ventilatory phase difficult, and the relatively high ventilation rates seen in small animals (rats and mice have ventilation rates in the range of a hundred cycles per minute), which challenges the capture rate of many imaging systems (this is particularly true of our system which utilizes cone-beam geometry and a 2 dimensional detector). Instead of pre-capture ventilation gating we implemented a method of post-acquisition gating. We acquire a sequence of projections images at 30 frames per second for each of 360 viewing angles. During each capture sequence the rat undergoes multiple ventilation cycles. Using the sequence of projection images, an automated region of interest algorithm, based on integrated grayscale intensity, tracts the ventilatory phase of the lungs. In the processing of an image sequence, multiple projection images are identified at a particular phase and averaged to improve the signal-to-ratio. The resulting averaged projection images are input to a Feldkamp cone-beam algorithm reconstruction algorithm in order to obtain isotropic image volumes. Minimal motion artifact data sets improve qualitative and quantitative analysis techniques useful in physiologic studies of pulmonary structure and function.

  4. Assessment of acquisition protocols for routine imaging of Y-90 using PET/CT

    PubMed Central

    2013-01-01

    Background Despite the early theoretical prediction of the 0+-0+ transition of 90Zr, 90Y-PET underwent only recently a growing interest for the development of imaging radioembolization of liver tumors. The aim of this work was to determine the minimum detectable activity (MDA) of 90Y by PET imaging and the impact of time-of-flight (TOF) reconstruction on detectability and quantitative accuracy according to the lesion size. Methods The study was conducted using a Siemens Biograph® mCT with a 22 cm large axial field of view. An IEC torso-shaped phantom containing five coplanar spheres was uniformly filled to achieve sphere-to-background ratios of 40:1. The phantom was imaged nine times in 14 days over 30 min. Sinograms were reconstructed with and without TOF information. A contrast-to-noise ratio (CNR) index was calculated using the Rose criterion, taking partial volume effects into account. The impact of reconstruction parameters on quantification accuracy, detectability, and spatial localization of the signal was investigated. Finally, six patients with hepatocellular carcinoma and four patients included in different 90Y-based radioimmunotherapy protocols were enrolled for the evaluation of the imaging parameters in a clinical situation. Results The highest CNR was achieved with one iteration for both TOF and non-TOF reconstructions. The MDA, however, was found to be lower with TOF than with non-TOF reconstruction. There was no gain by adding TOF information in terms of CNR for concentrations higher than 2 to 3 MBq mL−1, except for infra-centimetric lesions. Recovered activity was highly underestimated when a single iteration or non-TOF reconstruction was used (10% to 150% less depending on the lesion size). The MDA was estimated at 1 MBq mL−1 for a TOF reconstruction and infra-centimetric lesions. Images from patients treated with microspheres were clinically relevant, unlike those of patients who received systemic injections of 90Y. Conclusions Only

  5. Soft Route to 4D Tomography

    NASA Astrophysics Data System (ADS)

    Taillandier-Thomas, Thibault; Roux, Stéphane; Hild, François

    2016-07-01

    Based on the assumption that the time evolution of a sample observed by computed tomography requires many less parameters than the definition of the microstructure itself, it is proposed to reconstruct these changes based on the initial state (using computed tomography) and very few radiographs acquired at fixed intervals of time. This Letter presents a proof of concept that for a fatigue cracked sample its kinematics can be tracked from no more than two radiographs in situations where a complete 3D view would require several hundreds of radiographs. This 2 order of magnitude gain opens the way to a "computed" 4D tomography, which complements the recent progress achieved in fast or ultrafast computed tomography, which is based on beam brightness, detector sensitivity, and signal acquisition technologies.

  6. 4D Proton treatment planning strategy for mobile lung tumors

    SciTech Connect

    Kang Yixiu; Zhang Xiaodong; Chang, Joe Y.; Wang He; Wei Xiong; Liao Zhongxing; Komaki, Ritsuko; Cox, James D.; Balter, Peter A.; Liu, Helen; Zhu, X. Ronald; Mohan, Radhe; Dong Lei . E-mail: ldong@mdanderson.org

    2007-03-01

    Purpose: To investigate strategies for designing compensator-based 3D proton treatment plans for mobile lung tumors using four-dimensional computed tomography (4DCT) images. Methods and Materials: Four-dimensional CT sets for 10 lung cancer patients were used in this study. The internal gross tumor volume (IGTV) was obtained by combining the tumor volumes at different phases of the respiratory cycle. For each patient, we evaluated four planning strategies based on the following dose calculations: (1) the average (AVE) CT; (2) the free-breathing (FB) CT; (3) the maximum intensity projection (MIP) CT; and (4) the AVE CT in which the CT voxel values inside the IGTV were replaced by a constant density (AVE{sub R}IGTV). For each strategy, the resulting cumulative dose distribution in a respiratory cycle was determined using a deformable image registration method. Results: There were dosimetric differences between the apparent dose distribution, calculated on a single CT dataset, and the motion-corrected 4D dose distribution, calculated by combining dose distributions delivered to each phase of the 4DCT. The AVE{sub R}IGTV plan using a 1-cm smearing parameter had the best overall target coverage and critical structure sparing. The MIP plan approach resulted in an unnecessarily large treatment volume. The AVE and FB plans using 1-cm smearing did not provide adequate 4D target coverage in all patients. By using a larger smearing value, adequate 4D target coverage could be achieved; however, critical organ doses were increased. Conclusion: The AVE{sub R}IGTV approach is an effective strategy for designing proton treatment plans for mobile lung tumors.

  7. Fast 4D segmentation of large datasets using graph cuts

    NASA Astrophysics Data System (ADS)

    Lombaert, Herve; Sun, Yiyong; Cheriet, Farida

    2011-03-01

    In this paper, we propose to use 4D graph cuts for the segmentation of large spatio-temporal (4D) datasets. Indeed, as 4D datasets grow in popularity in many clinical areas, so will the demand for efficient general segmentation algorithms. The graph cuts method1 has become a leading method for complex 2D and 3D image segmentation in many applications. Despite a few attempts2-5 in 4D, the use of graph cuts on typical medical volume quickly exceeds today's computer capacities. Among all existing graph cuts based methods6-10 the multilevel banded graph cuts9 is the fastest and uses the least amount of memory. Nevertheless, this method has its limitation. Memory becomes an issue when using large 4D volume sequences, and small structures become hardly recoverable when using narrow bands. We thus improve the boundary refinement efficiency by using a 4D competitive region growing. First, we construct a coarse graph at a low resolution with strong temporal links to prevent the shrink bias inherent to the graph cuts method. Second, we use a competitive region growing using a priority queue to capture all fine details. Leaks are prevented by constraining the competitive region growing within a banded region and by adding a viscosity term. This strategy yields results comparable to the multilevel banded graph cuts but is faster and allows its application to large 4D datasets. We applied our method on both cardiac 4D MRI and 4D CT datasets with promising results.

  8. Diagnostic Phase of Calcium Scoring Scan Applied as the Center of Acquisition Window of Coronary Computed Tomography Angiography Improves Image Quality in Minimal Acquisition Window Scan (Target CTA Mode) Using the Second Generation 320-Row CT

    PubMed Central

    Maeda, Eriko; Kanno, Shigeaki; Ino, Kenji; Tomizawa, Nobuo; Akahane, Masaaki; Torigoe, Rumiko; Ohtomo, Kuni

    2016-01-01

    Objective. To compare the image quality of coronary computed tomography angiography (CCTA) acquired under two conditions: 75% fixed as the acquisition window center (Group 75%) and the diagnostic phase for calcium scoring scan as the center (CS; Group CS). Methods. 320-row cardiac CT with a minimal acquisition window (scanned using “Target CTA” mode) was performed on 81 patients. In Group 75% (n = 40), CS was obtained and reconstructed at 75% and the center of the CCTA acquisition window was set at 75%. In Group CS (n = 41), CS was obtained at 75% and the diagnostic phase showing minimal artifacts was applied as the center of the CCTA acquisition window. Image quality was evaluated using a four-point scale (4-excellent) and the mean scores were compared between groups. Results. The CCTA scan diagnostic phase occurred significantly earlier in CS (75.7 ± 3.2% vs. 73.6 ± 4.5% for Groups 75% and CS, resp., p = 0.013). The mean Group CS image quality score (3.58 ± 0.63) was also higher than that for Group 75% (3.19 ± 0.66, p < 0.0001). Conclusions. The image quality of CCTA in Target CTA mode was significantly better when the center of acquisition window is adjusted using CS. PMID:26977449

  9. SU-E-I-91: Reproducibility in Prescribed Dose in AEC CT Scans Due to Table Height, Patient Size, and Localizer Acquisition Order

    SciTech Connect

    Winslow, J; Hurwitz, L; Christianson, O; Samei, E

    2014-06-01

    Purpose: In CT scanners, the automatic exposure control (AEC) tube current prescription depends on the acquired prescan localizer image(s). The purpose of this study was to quantify the effect that table height, patient size, and localizer acquisition order may have on the reproducibility in prescribed dose. Methods: Three phantoms were used for this study: the Mercury Phantom (comprises three tapered and four uniform regions of polyethylene 16, 23, 30, and 37 cm in diameter), acrylic sheets, and an adult anthropomorphic phantom. Phantoms were positioned per clinical protocol by our chief CT technologist or broader symmetry. Using a GE Discovery CT750HD scanner, a lateral (LAT) and posterior-anterior (PA) localizer was acquired for each phantom at different table heights. AEC scan acquisitions were prescribed for each combination of phantom, localizer orientation, and table height; the displayed volume CTDI was recorded for each. Results were analyzed versus table height. Results: For the two largest Mercury Phantom section scans based on the PA localizer, the percent change in volume CTDI from ideal were at least 20% lower and 35% greater for table heights 4 cm above and 4 cm below proper centering, respectively. For scans based on the LAT localizer, the percent change in volume CTDI from ideal were no greater than 12% different for 4 cm differences in table height. The properly centered PA and LAT localizer-based volume CTDI values were within 13% of each other. Conclusion: Since uncertainty in vertical patient positioning is inherently greater than lateral positioning and because the variability in dose exceeds any dose penalties incurred, the LAT localizer should be used to precisely and reproducibly deliver the intended amount of radiation prescribed by CT protocols. CT protocols can be adjusted to minimize the expected change in average patient dose.

  10. 4D-DSA and 4D fluoroscopy: preliminary implementation

    NASA Astrophysics Data System (ADS)

    Mistretta, C. A.; Oberstar, E.; Davis, B.; Brodsky, E.; Strother, C. M.

    2010-04-01

    We have described methods that allow highly accelerated MRI using under-sampled acquisitions and constrained reconstruction. One is a hybrid acquisition involving the constrained reconstruction of time dependent information obtained from a separate scan of longer duration. We have developed reconstruction algorithms for DSA that allow use of a single injection to provide the temporal data required for flow visualization and the steady state data required for construction of a 3D-DSA vascular volume. The result is time resolved 3D volumes with typical resolution of 5123 at frame rates of 20-30 fps. Full manipulation of these images is possible during each stage of vascular filling thereby allowing for simplified interpretation of vascular dynamics. For intravenous angiography this time resolved 3D capability overcomes the vessel overlap problem that greatly limited the use of conventional intravenous 2D-DSA. Following further hardware development, it will be also be possible to rotate fluoroscopic volumes for use as roadmaps that can be viewed at arbitrary angles without a need for gantry rotation. The most precise implementation of this capability requires availability of biplane fluoroscopy data. Since the reconstruction of 3D volumes presently suppresses the contrast in the soft tissue, the possibility of using these techniques to derive complete indications of perfusion deficits based on cerebral blood volume (CBV), mean transit time (MTT) and time to peak (TTP) parameters requires further investigation. Using MATLAB post-processing, successful studies in animals and humans done in conjunction with both intravenous and intra-arterial injections have been completed. Real time implementation is in progress.

  11. A technique for estimating 4D-CBCT using prior knowledge and limited-angle projections

    SciTech Connect

    Zhang, You; Yin, Fang-Fang; Ren, Lei; Segars, W. Paul

    2013-12-15

    Purpose: To develop a technique to estimate onboard 4D-CBCT using prior information and limited-angle projections for potential 4D target verification of lung radiotherapy.Methods: Each phase of onboard 4D-CBCT is considered as a deformation from one selected phase (prior volume) of the planning 4D-CT. The deformation field maps (DFMs) are solved using a motion modeling and free-form deformation (MM-FD) technique. In the MM-FD technique, the DFMs are estimated using a motion model which is extracted from planning 4D-CT based on principal component analysis (PCA). The motion model parameters are optimized by matching the digitally reconstructed radiographs of the deformed volumes to the limited-angle onboard projections (data fidelity constraint). Afterward, the estimated DFMs are fine-tuned using a FD model based on data fidelity constraint and deformation energy minimization. The 4D digital extended-cardiac-torso phantom was used to evaluate the MM-FD technique. A lung patient with a 30 mm diameter lesion was simulated with various anatomical and respirational changes from planning 4D-CT to onboard volume, including changes of respiration amplitude, lesion size and lesion average-position, and phase shift between lesion and body respiratory cycle. The lesions were contoured in both the estimated and “ground-truth” onboard 4D-CBCT for comparison. 3D volume percentage-difference (VPD) and center-of-mass shift (COMS) were calculated to evaluate the estimation accuracy of three techniques: MM-FD, MM-only, and FD-only. Different onboard projection acquisition scenarios and projection noise levels were simulated to investigate their effects on the estimation accuracy.Results: For all simulated patient and projection acquisition scenarios, the mean VPD (±S.D.)/COMS (±S.D.) between lesions in prior images and “ground-truth” onboard images were 136.11% (±42.76%)/15.5 mm (±3.9 mm). Using orthogonal-view 15°-each scan angle, the mean VPD/COMS between the lesion

  12. Quantication and analysis of respiratory motion from 4D MRI

    NASA Astrophysics Data System (ADS)

    Aizzuddin Abd Rahni, Ashrani; Lewis, Emma; Wells, Kevin

    2014-11-01

    It is well known that respiratory motion affects image acquisition and also external beam radiotherapy (EBRT) treatment planning and delivery. However often the existing approaches for respiratory motion management are based on a generic view of respiratory motion such as the general movement of organ, tissue or fiducials. This paper thus aims to present a more in depth analysis of respiratory motion based on 4D MRI for further integration into motion correction in image acquisition or image based EBRT. Internal and external motion was first analysed separately, on a per-organ basis for internal motion. Principal component analysis (PCA) was then performed on the internal and external motion vectors separately and the relationship between the two PCA spaces was analysed. The motion extracted from 4D MRI on general was found to be consistent with what has been reported in literature.

  13. Validation of a 4D-PET Maximum Intensity Projection for Delineation of an Internal Target Volume

    SciTech Connect

    Callahan, Jason; Kron, Tomas; Schneider-Kolsky, Michal; Dunn, Leon; Thompson, Mick; Siva, Shankar; Aarons, Yolanda; Binns, David; Hicks, Rodney J.

    2013-07-15

    Purpose: The delineation of internal target volumes (ITVs) in radiation therapy of lung tumors is currently performed by use of either free-breathing (FB) {sup 18}F-fluorodeoxyglucose-positron emission tomography-computed tomography (FDG-PET/CT) or 4-dimensional (4D)-CT maximum intensity projection (MIP). In this report we validate the use of 4D-PET-MIP for the delineation of target volumes in both a phantom and in patients. Methods and Materials: A phantom with 3 hollow spheres was prepared surrounded by air then water. The spheres and water background were filled with a mixture of {sup 18}F and radiographic contrast medium. A 4D-PET/CT scan was performed of the phantom while moving in 4 different breathing patterns using a programmable motion device. Nine patients with an FDG-avid lung tumor who underwent FB and 4D-PET/CT and >5 mm of tumor motion were included for analysis. The 3 spheres and patient lesions were contoured by 2 contouring methods (40% of maximum and PET edge) on the FB-PET, FB-CT, 4D-PET, 4D-PET-MIP, and 4D-CT-MIP. The concordance between the different contoured volumes was calculated using a Dice coefficient (DC). The difference in lung tumor volumes between FB-PET and 4D-PET volumes was also measured. Results: The average DC in the phantom using 40% and PET edge, respectively, was lowest for FB-PET/CT (DCAir = 0.72/0.67, DCBackground 0.63/0.62) and highest for 4D-PET/CT-MIP (DCAir = 0.84/0.83, DCBackground = 0.78/0.73). The average DC in the 9 patients using 40% and PET edge, respectively, was also lowest for FB-PET/CT (DC = 0.45/0.44) and highest for 4D-PET/CT-MIP (DC = 0.72/0.73). In the 9 lesions, the target volumes of the FB-PET using 40% and PET edge, respectively, were on average 40% and 45% smaller than the 4D-PET-MIP. Conclusion: A 4D-PET-MIP produces volumes with the highest concordance with 4D-CT-MIP across multiple breathing patterns and lesion sizes in both a phantom and among patients. Freebreathing PET/CT consistently

  14. Comparison of effective dose and lifetime risk of cancer incidence of CT attenuation correction acquisitions and radiopharmaceutical administration for myocardial perfusion imaging

    PubMed Central

    Szczepura, K; Hogg, P

    2014-01-01

    Objective: To measure the organ dose and calculate effective dose from CT attenuation correction (CTAC) acquisitions from four commonly used gamma camera single photon emission CT/CT systems. Methods: CTAC dosimetry data was collected using thermoluminescent dosemeters on GE Healthcare's Infinia™ Hawkeye™ (GE Healthcare, Buckinghamshire, UK) four- and single-slice systems, Siemens Symbia™ T6 (Siemens Healthcare, Erlangen, Germany) and the Philips Precedence (Philips Healthcare, Amsterdam, Netherlands). Organ and effective dose from the administration of 99mTc-tetrofosmin and 99mTc-sestamibi were calculated using International Commission of Radiological Protection reports 80 and 106. Using these data, the lifetime biological risk was calculated. Results: The Siemens Symbia gave the lowest CTAC dose (1.8 mSv) followed by the GE Infinia Hawkeye single-slice (1.9 mSv), GE Infinia Hawkeye four-slice (2.5 mSv) and Philips Precedence v. 3.0. Doses were significantly lower than the calculated doses from radiopharmaceutical administration (11 and 14 mSv for 99mTc-tetrofosmin and 99mTc-sestamibi, respectively). Overall lifetime biological risks were lower, which suggests that using CTAC data posed minimal risk to the patient. Comparison of data for breast tissue demonstrated a higher risk than that from the radiopharmaceutical administration. Conclusion: CTAC doses were confirmed to be much lower than those from radiopharmaceutical administration. The localized nature of the CTAC exposure compared to the radiopharmaceutical biological distribution indicated dose and risk to the breast to be higher. Advances in knowledge: This research proved that CTAC is a comparatively low-dose acquisition. However, it has been shown that there is increased risk for breast tissue especially in the younger patients. As per legislation, justification is required and CTAC should only be used in situations that demonstrate sufficient net benefit. PMID:24998249

  15. 4-D OCT in Developmental Cardiology

    NASA Astrophysics Data System (ADS)

    Jenkins, Michael W.; Rollins, Andrew M.

    Although strong evidence exists to suggest that altered cardiac function can lead to CHDs, few studies have investigated the influential role of cardiac function and biophysical forces on the development of the cardiovascular system due to a lack of proper in vivo imaging tools. 4-D imaging is needed to decipher the complex spatial and temporal patterns of biomechanical forces acting upon the heart. Numerous solutions over the past several years have demonstrated 4-D OCT imaging of the developing cardiovascular system. This chapter will focus on these solutions and explain their context in the evolution of 4-D OCT imaging. The first sections describe the relevant techniques (prospective gating, direct 4-D imaging, retrospective gating), while later sections focus on 4-D Doppler imaging and measurements of force implementing 4-D OCT Doppler. Finally, the techniques are summarized, and some possible future directions are discussed.

  16. 4D VMAT, gated VMAT, and 3D VMAT for stereotactic body radiation therapy in lung

    NASA Astrophysics Data System (ADS)

    Chin, E.; Loewen, S. K.; Nichol, A.; Otto, K.

    2013-02-01

    Four-dimensional volumetric modulated arc therapy (4D VMAT) is a treatment strategy for lung cancers that aims to exploit relative target and tissue motion to improve organ at risk (OAR) sparing. The algorithm incorporates the entire patient respiratory cycle using 4D CT data into the optimization process. Resulting treatment plans synchronize the delivery of each beam aperture to a specific phase of target motion. Stereotactic body radiation therapy treatment plans for 4D VMAT, gated VMAT, and 3D VMAT were generated on three patients with non-small cell lung cancer. Tumour motion ranged from 1.4-3.4 cm. The dose and fractionation scheme was 48 Gy in four fractions. A B-spline transformation model registered the 4D CT images. 4D dose volume histograms (4D DVH) were calculated from total dose accumulated at the maximum exhalation. For the majority of OARs, gated VMAT achieved the most radiation sparing but treatment times were 77-148% longer than 3D VMAT. 4D VMAT plan qualities were comparable to gated VMAT, but treatment times were only 11-25% longer than 3D VMAT. 4D VMAT's improvement of healthy tissue sparing can allow for further dose escalation. Future study could potentially adapt 4D VMAT to irregular patient breathing patterns.

  17. A sinogram warping strategy for pre-reconstruction 4D PET optimization.

    PubMed

    Gianoli, Chiara; Riboldi, Marco; Fontana, Giulia; Kurz, Christopher; Parodi, Katia; Baroni, Guido

    2016-03-01

    A novel strategy for 4D PET optimization in the sinogram domain is proposed, aiming at motion model application before image reconstruction ("sinogram warping" strategy). Compared to state-of-the-art 4D-MLEM reconstruction, the proposed strategy is able to optimize the image SNR, avoiding iterative direct and inverse warping procedures, which are typical of the 4D-MLEM algorithm. A full-count statistics sinogram of the motion-compensated 4D PET reference phase is generated by warping the sinograms corresponding to the different PET phases. This is achieved relying on a motion model expressed in the sinogram domain. The strategy was tested on the anthropomorphic 4D PET-CT NCAT phantom in comparison with the 4D-MLEM algorithm, with particular reference to robustness to PET-CT co-registrations artefacts. The MLEM reconstruction of the warped sinogram according to the proposed strategy exhibited better accuracy (up to +40.90 % with respect to the ideal value), whereas images reconstructed according to the 4D-MLEM reconstruction resulted in less noisy (down to -26.90 % with respect to the ideal value) but more blurred. The sinogram warping strategy demonstrates advantages with respect to 4D-MLEM algorithm. These advantages are paid back by introducing approximation of the deformation field, and further efforts are required to mitigate the impact of such an approximation in clinical 4D PET reconstruction. PMID:26126871

  18. 4D flow mri post-processing strategies for neuropathologies

    NASA Astrophysics Data System (ADS)

    Schrauben, Eric Mathew

    4D flow MRI allows for the measurement of a dynamic 3D velocity vector field. Blood flow velocities in large vascular territories can be qualitatively visualized with the added benefit of quantitative probing. Within cranial pathologies theorized to have vascular-based contributions or effects, 4D flow MRI provides a unique platform for comprehensive assessment of hemodynamic parameters. Targeted blood flow derived measurements, such as flow rate, pulsatility, retrograde flow, or wall shear stress may provide insight into the onset or characterization of more complex neuropathologies. Therefore, the thorough assessment of each parameter within the context of a given disease has important medical implications. Not surprisingly, the last decade has seen rapid growth in the use of 4D flow MRI. Data acquisition sequences are available to researchers on all major scanner platforms. However, the use has been limited mostly to small research trials. One major reason that has hindered the more widespread use and application in larger clinical trials is the complexity of the post-processing tasks and the lack of adequate tools for these tasks. Post-processing of 4D flow MRI must be semi-automated, fast, user-independent, robust, and reliably consistent for use in a clinical setting, within large patient studies, or across a multicenter trial. Development of proper post-processing methods coupled with systematic investigation in normal and patient populations pushes 4D flow MRI closer to clinical realization while elucidating potential underlying neuropathological origins. Within this framework, the work in this thesis assesses venous flow reproducibility and internal consistency in a healthy population. A preliminary analysis of venous flow parameters in healthy controls and multiple sclerosis patients is performed in a large study employing 4D flow MRI. These studies are performed in the context of the chronic cerebrospinal venous insufficiency hypothesis. Additionally, a

  19. 4D flow imaging: current status to future clinical applications.

    PubMed

    Markl, Michael; Schnell, Susanne; Barker, Alex J

    2014-05-01

    4D flow MRI permits a comprehensive in-vivo assessment of three-directional blood flow within 3-dimensional vascular structures throughout the cardiac cycle. Given the large coverage permitted from a 4D flow acquisition, the distribution of vessel wall and flow parameters along an entire vessel of interest can thus be derived from a single measurement without being dependent on multiple predefined 2D acquisitions. In addition to qualitative 3D visualizations of complex cardiac and vascular flow patterns, quantitative flow analysis can be performed and is complemented by the ability to compute sophisticated hemodynamic parameters, such as wall shear stress or 3D pressure difference maps. These metrics can provide information previously unavailable with conventional modalities regarding the impact of cardiovascular disease or therapy on global and regional changes in hemodynamics. This review provides an introduction to the methodological aspects of 4D flow MRI to assess vascular hemodynamics and describes its potential for the assessment and understanding of altered hemodynamics in the presence of cardiovascular disease. PMID:24700368

  20. 4D microvascular imaging based on ultrafast Doppler tomography.

    PubMed

    Demené, Charlie; Tiran, Elodie; Sieu, Lim-Anna; Bergel, Antoine; Gennisson, Jean Luc; Pernot, Mathieu; Deffieux, Thomas; Cohen, Ivan; Tanter, Mickael

    2016-02-15

    4D ultrasound microvascular imaging was demonstrated by applying ultrafast Doppler tomography (UFD-T) to the imaging of brain hemodynamics in rodents. In vivo real-time imaging of the rat brain was performed using ultrasonic plane wave transmissions at very high frame rates (18,000 frames per second). Such ultrafast frame rates allow for highly sensitive and wide-field-of-view 2D Doppler imaging of blood vessels far beyond conventional ultrasonography. Voxel anisotropy (100 μm × 100 μm × 500 μm) was corrected for by using a tomographic approach, which consisted of ultrafast acquisitions repeated for different imaging plane orientations over multiple cardiac cycles. UFT-D allows for 4D dynamic microvascular imaging of deep-seated vasculature (up to 20 mm) with a very high 4D resolution (respectively 100 μm × 100 μm × 100 μm and 10 ms) and high sensitivity to flow in small vessels (>1 mm/s) for a whole-brain imaging technique without requiring any contrast agent. 4D ultrasound microvascular imaging in vivo could become a valuable tool for the study of brain hemodynamics, such as cerebral flow autoregulation or vascular remodeling after ischemic stroke recovery, and, more generally, tumor vasculature response to therapeutic treatment. PMID:26555279

  1. 4D MRI for the Localization of Parathyroid Adenoma: A Novel Method in Evolution.

    PubMed

    Merchavy, Shlomo; Luckman, Judith; Guindy, Michal; Segev, Yoram; Khafif, Avi

    2016-03-01

    The sestamibi scan (MIBI) and ultrasound (US) are used for preoperative localization of parathyroid adenoma (PTA), with sensitivity as high as 90%. We developed 4-dimensional magnetic resonance imaging (4D MRI) as a novel tool for identifying PTAs. Eleven patients with PTA were enrolled. 4D MRI from the mandible to the aortic arch was used. Optimization of the timing of image acquisition was obtained by changing dynamic and static sequences. PTAs were identified in all except 1 patient. In 9 patients, there was a complete match between the 4D MRI and the US and MIBI, as well as with the operative finding. In 1 patient, the adenoma was correctly localized by 4D MRI, in contrast to the US and MIBI scan. The sensitivity of the 4D MRI was 90% and after optimization, 100%. Specificity was 100%. We concluded that 4D MRI is a reliable technique for identification of PTAs, although more studies are needed. PMID:26598499

  2. SU-E-J-74: Impact of Respiration-Correlated Image Quality On Tumor Motion Reconstruction in 4D-CBCT: A Phantom Study

    SciTech Connect

    Lee, S; Lu, B; Samant, S

    2014-06-01

    Purpose: To investigate the effects of scanning parameters and respiratory patterns on the image quality for 4-dimensional cone-beam computed tomography(4D-CBCT) imaging, and assess the accuracy of computed tumor trajectory for lung imaging using registration of phased 4D-CBCT imaging with treatment planning-CT. Methods: We simulated a periodic and non-sinusoidal respirations with various breathing periods and amplitudes using a respiratory phantom(Quasar, Modus Medical Devices Inc) to acquire respiration-correlated 4D-CBCT images. 4D-CBCT scans(Elekta Oncology Systems Ltd) were performed with different scanning parameters for collimation size(e.g., small and medium field-of-views) and scanning speed(e.g., slow 50°·min{sup −1}, fast 100°·min{sup −1}). Using a standard CBCT-QA phantom(Catphan500, The Phantom Laboratory), the image qualities of all phases in 4D-CBCT were evaluated with contrast-to-noise ratio(CNR) for lung tissue and uniformity in each module. Using a respiratory phantom, the target imaging in 4D-CBCT was compared to 3D-CBCT target image. The target trajectory from 10-respiratory phases in 4D-CBCT was extracted using an automatic image registration and subsequently assessed the accuracy by comparing with actual motion of the target. Results: Image analysis indicated that a short respiration with a small amplitude resulted in superior CNR and uniformity. Smaller variation of CNR and uniformity was present amongst different respiratory phases. The small field-of-view with a partial scan using slow scan can improve CNR, but degraded uniformity. Large amplitude of respiration can degrade image quality. RMS of voxel densities in tumor area of 4D-CBCT images between sinusoidal and non-sinusoidal motion exhibited no significant difference. The maximum displacement errors of motion trajectories were less than 1.0 mm and 13.5 mm, for sinusoidal and non-sinusoidal breathings, respectively. The accuracy of motion reconstruction showed good overall

  3. SU-E-J-246: A Deformation-Field Map Based Liver 4D CBCT Reconstruction Method Using Gold Nanoparticles as Constraints

    SciTech Connect

    Harris, W; Zhang, Y; Ren, L; Yin, F

    2014-06-01

    Purpose: To investigate the feasibility of using nanoparticle markers to validate liver tumor motion together with a deformation field map-based four dimensional (4D) cone-beam computed tomography (CBCT) reconstruction method. Methods: A technique for lung 4D-CBCT reconstruction has been previously developed using a deformation field map (DFM)-based strategy. In this method, each phase of the 4D-CBCT is considered as a deformation of a prior CT volume. The DFM is solved by a motion modeling and free-form deformation (MM-FD) technique, using a data fidelity constraint and the deformation energy minimization. For liver imaging, there is low contrast of a liver tumor in on-board projections. A validation of liver tumor motion using implanted gold nanoparticles, along with the MM-FD deformation technique is implemented to reconstruct onboard 4D CBCT liver radiotherapy images. These nanoparticles were placed around the liver tumor to reflect the tumor positions in both CT simulation and on-board image acquisition. When reconstructing each phase of the 4D-CBCT, the migrations of the gold nanoparticles act as a constraint to regularize the deformation field, along with the data fidelity and the energy minimization constraints. In this study, multiple tumor diameters and positions were simulated within the liver for on-board 4D-CBCT imaging. The on-board 4D-CBCT reconstructed by the proposed method was compared with the “ground truth” image. Results: The preliminary data, which uses reconstruction for lung radiotherapy suggests that the advanced reconstruction algorithm including the gold nanoparticle constraint will Resultin volume percentage differences (VPD) between lesions in reconstructed images by MM-FD and “ground truth” on-board images of 11.5% (± 9.4%) and a center of mass shift of 1.3 mm (± 1.3 mm) for liver radiotherapy. Conclusion: The advanced MM-FD technique enforcing the additional constraints from gold nanoparticles, results in improved accuracy

  4. 4D XCAT phantom for multimodality imaging research

    SciTech Connect

    Segars, W. P.; Sturgeon, G.; Mendonca, S.; Grimes, Jason; Tsui, B. M. W.

    2010-09-15

    Purpose: The authors develop the 4D extended cardiac-torso (XCAT) phantom for multimodality imaging research. Methods: Highly detailed whole-body anatomies for the adult male and female were defined in the XCAT using nonuniform rational B-spline (NURBS) and subdivision surfaces based on segmentation of the Visible Male and Female anatomical datasets from the National Library of Medicine as well as patient datasets. Using the flexibility of these surfaces, the Visible Human anatomies were transformed to match body measurements and organ volumes for a 50th percentile (height and weight) male and female. The desired body measurements for the models were obtained using the PEOPLESIZE program that contains anthropometric dimensions categorized from 1st to the 99th percentile for US adults. The desired organ volumes were determined from ICRP Publication 89 [ICRP, ''Basic anatomical and physiological data for use in radiological protection: reference values,'' ICRP Publication 89 (International Commission on Radiological Protection, New York, NY, 2002)]. The male and female anatomies serve as standard templates upon which anatomical variations may be modeled in the XCAT through user-defined parameters. Parametrized models for the cardiac and respiratory motions were also incorporated into the XCAT based on high-resolution cardiac- and respiratory-gated multislice CT data. To demonstrate the usefulness of the phantom, the authors show example simulation studies in PET, SPECT, and CT using publicly available simulation packages. Results: As demonstrated in the pilot studies, the 4D XCAT (which includes thousands of anatomical structures) can produce realistic imaging data when combined with accurate models of the imaging process. With the flexibility of the NURBS surface primitives, any number of different anatomies, cardiac or respiratory motions or patterns, and spatial resolutions can be simulated to perform imaging research. Conclusions: With the ability to produce

  5. 4D XCAT phantom for multimodality imaging research

    PubMed Central

    Segars, W. P.; Sturgeon, G.; Mendonca, S.; Grimes, Jason; Tsui, B. M. W.

    2010-01-01

    Purpose: The authors develop the 4D extended cardiac-torso (XCAT) phantom for multimodality imaging research. Methods: Highly detailed whole-body anatomies for the adult male and female were defined in the XCAT using nonuniform rational B-spline (NURBS) and subdivision surfaces based on segmentation of the Visible Male and Female anatomical datasets from the National Library of Medicine as well as patient datasets. Using the flexibility of these surfaces, the Visible Human anatomies were transformed to match body measurements and organ volumes for a 50th percentile (height and weight) male and female. The desired body measurements for the models were obtained using the PEOPLESIZE program that contains anthropometric dimensions categorized from 1st to the 99th percentile for US adults. The desired organ volumes were determined from ICRP Publication 89 [ICRP, ‘‘Basic anatomical and physiological data for use in radiological protection: reference values,” ICRP Publication 89 (International Commission on Radiological Protection, New York, NY, 2002)]. The male and female anatomies serve as standard templates upon which anatomical variations may be modeled in the XCAT through user-defined parameters. Parametrized models for the cardiac and respiratory motions were also incorporated into the XCAT based on high-resolution cardiac- and respiratory-gated multislice CT data. To demonstrate the usefulness of the phantom, the authors show example simulation studies in PET, SPECT, and CT using publicly available simulation packages. Results: As demonstrated in the pilot studies, the 4D XCAT (which includes thousands of anatomical structures) can produce realistic imaging data when combined with accurate models of the imaging process. With the flexibility of the NURBS surface primitives, any number of different anatomies, cardiac or respiratory motions or patterns, and spatial resolutions can be simulated to perform imaging research. Conclusions: With the ability to produce

  6. Image Quality and Radiation Dose of Lower Extremity CT Angiography Using 70 kVp, High Pitch Acquisition and Sinogram-Affirmed Iterative Reconstruction

    PubMed Central

    Qi, Li; Meinel, Felix G.; Zhou, Chang Sheng; Zhao, Yan E.; Schoepf, U. Joseph; Zhang, Long Jiang; Lu, Guang Ming

    2014-01-01

    Objectives The purpose of this study was to assess image quality and radiation dose of lower extremity CT angiography (CTA) with 70 kVp, high pitch acquisition and sinogram-affirmed iterative reconstruction (SAFIRE). Methods Lower extremity CTAs were performed on 44 patients: 22 patients were examined using protocol A (120 kVp, pitch of 0.85 and 120 ml of contrast agent on a first-generation dual-source CT) (120 kVp group) and 22 patients were evaluated with protocol B (70 kVp, pitch of 2.2 and 80 ml of contrast agent on a second-generation dual-source CT) (70 kVp group). Images from the 120 kVp group were reconstructed with filtered back projection (FBP) and images from the 70 kVp group with SAFIRE. The attenuation, image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Two radiologists subjectively assessed image quality of lower extremity arteries, plantar arterial enhancement and venous contamination of all patients. Radiation dose was compared between the two groups. Results Higher mean intravascular attenuation was obtained in the 70 kVp group (70 vs. 120 kVp group, 555.4±83.4 HU vs. 300.9±81.4 HU, P<0.001), as well as image noise (20.0±2.8 HU vs. 17.5±3.2 HU, P = 0.010), SNR (32.0±7.0 vs. 19.1±6.9, P<0.001) and CNR (28.1±6.6 vs 15.9±6.3, P<0.001). No difference in subjective image quality and plantar arterial enhancement was found between 120 kVp group and 70 kVp group (all P>0.05). The venous contamination score was 1.5±0.8 for 120 kVp group while no venous contamination was found in 70 kVp group. The inter-observer agreement was moderate to good for both groups (0.515∼1, P<0.001). The effective dose was lower in 70 kVp group (0.3±0.1 mSv) than in 120 kVp group (1.6±0.7 mSv)(P<0.001). Conclusions Lower extremity CTA using 70 kVp, high pitch acquisition and SAFIRE, except increasing imaging noise, allows for lower radiation dose and contrast material volume without compromising image quality. PMID

  7. Los Alamos National Laboratory 4D Database

    SciTech Connect

    Atencio, Julian J.

    2014-05-02

    4D is an integrated development platform - a single product comprised of the components you need to create and distribute professional applications. You get a graphical design environment, SQL database, a programming language, integrated PHP execution, HTTP server, application server, executable generator, and much more. 4D offers multi-platform development and deployment, meaning whatever you create on a Mac can be used on Windows, and vice-versa. Beyond productive development, 4D is renowned for its great flexibility in maintenance and modification of existing applications, and its extreme ease of implementation in its numerous deployment options. Your professional application can be put into production more quickly, at a lower cost, and will always be instantly scalable. 4D makes it easy, whether you're looking to create a classic desktop application, a client-server system, a distributed solution for Web or mobile clients - or all of the above!

  8. Computing Myocardial Motion in 4D Echocardiography

    PubMed Central

    Mukherjee, Ryan; Sprouse, Chad; Pinheiro, Aurélio; Abraham, Theodore; Burlina, Philippe

    2012-01-01

    4D (3D spatial+time) echocardiography is gaining widespread acceptance at clinical institutions for its high temporal resolution and relatively low cost. We describe a novel method for computing dense 3D myocardial motion with high accuracy. The method is based on a classical variational optical flow technique, but exploits modern developments in optical flow research to utilize the full capabilities of 4D echocardiography. Using a variety of metrics, we present an in-depth performance evaluation of the method on synthetic, phantom, and intraoperative 4D Transesophageal Echocardiographic (TEE) data. When compared with state-of-the-art optical flow and speckle tracking techniques currently found in 4D echocardiography, the method we present shows notable improvements in error. We believe the performance improvements shown can have a positive impact when the method is used as input for various applications, such as strain computation, biomechanical modeling, or automated diagnostics. PMID:22677256

  9. Denoising and artefact reduction in dynamic flat detector CT perfusion imaging using high speed acquisition: first experimental and clinical results.

    PubMed

    Manhart, Michael T; Aichert, André; Struffert, Tobias; Deuerling-Zheng, Yu; Kowarschik, Markus; Maier, Andreas K; Hornegger, Joachim; Doerfler, Arnd

    2014-08-21

    Flat detector CT perfusion (FD-CTP) is a novel technique using C-arm angiography systems for interventional dynamic tissue perfusion measurement with high potential benefits for catheter-guided treatment of stroke. However, FD-CTP is challenging since C-arms rotate slower than conventional CT systems. Furthermore, noise and artefacts affect the measurement of contrast agent flow in tissue. Recent robotic C-arms are able to use high speed protocols (HSP), which allow sampling of the contrast agent flow with improved temporal resolution. However, low angular sampling of projection images leads to streak artefacts, which are translated to the perfusion maps. We recently introduced the FDK-JBF denoising technique based on Feldkamp (FDK) reconstruction followed by joint bilateral filtering (JBF). As this edge-preserving noise reduction preserves streak artefacts, an empirical streak reduction (SR) technique is presented in this work. The SR method exploits spatial and temporal information in the form of total variation and time-curve analysis to detect and remove streaks. The novel approach is evaluated in a numerical brain phantom and a patient study. An improved noise and artefact reduction compared to existing post-processing methods and faster computation speed compared to an algebraic reconstruction method are achieved. PMID:25069101

  10. Denoising and artefact reduction in dynamic flat detector CT perfusion imaging using high speed acquisition: first experimental and clinical results

    NASA Astrophysics Data System (ADS)

    Manhart, Michael T.; Aichert, André; Struffert, Tobias; Deuerling-Zheng, Yu; Kowarschik, Markus; Maier, Andreas K.; Hornegger, Joachim; Doerfler, Arnd

    2014-08-01

    Flat detector CT perfusion (FD-CTP) is a novel technique using C-arm angiography systems for interventional dynamic tissue perfusion measurement with high potential benefits for catheter-guided treatment of stroke. However, FD-CTP is challenging since C-arms rotate slower than conventional CT systems. Furthermore, noise and artefacts affect the measurement of contrast agent flow in tissue. Recent robotic C-arms are able to use high speed protocols (HSP), which allow sampling of the contrast agent flow with improved temporal resolution. However, low angular sampling of projection images leads to streak artefacts, which are translated to the perfusion maps. We recently introduced the FDK-JBF denoising technique based on Feldkamp (FDK) reconstruction followed by joint bilateral filtering (JBF). As this edge-preserving noise reduction preserves streak artefacts, an empirical streak reduction (SR) technique is presented in this work. The SR method exploits spatial and temporal information in the form of total variation and time-curve analysis to detect and remove streaks. The novel approach is evaluated in a numerical brain phantom and a patient study. An improved noise and artefact reduction compared to existing post-processing methods and faster computation speed compared to an algebraic reconstruction method are achieved.

  11. X-ray flat-panel imager (FPI)-based cone-beam volume CT (CBVCT) under a circle-plus-two-arc data acquisition orbit

    NASA Astrophysics Data System (ADS)

    Tang, Xiangyang; Ning, Ruola; Yu, Rongfeng; Conover, David L.

    2001-06-01

    The potential of cone beam volume CT (CBVCT) to improve the data acquisition efficiency for volume tomographic imaging is well recognized. A novel x-ray FPI based CBVCT prototype and its preliminary performance evaluation are presented in this paper. To meet the data sufficiency condition, the CBVCT prototype employs a circle-plus-two-arc orbit accomplished by a tiltable circular gantry. A cone beam filtered back-projection (CB-FBP) algorithm is derived for this data acquisition orbit, which employs a window function in the Radon domain to exclude the redundancy between the Radon information obtained from the circular cone beam (CB) data and that from the arc CB data. The number of projection images along the circular sub-orbit and each arc sub-orbit is 512 and 43, respectively. The reconstruction exactness of the prototype x-ray FPI based CBVCT system is evaluated using a disc phantom in which seven acrylic discs are stacked at fixed intervals. Images reconstructed with this algorithm show that both the contrast and geometric distortion existing in the disc phantom images reconstructed by the Feldkamp algorithm are substantially reduced. Meanwhile, the imaging performance of the prototype, such as modulation transfer function (MTF) and low contrast resolution, are quantitatively evaluated in detail through corresponding phantom studies. Furthermore, the capability of the prototype to reconstruct an ROI within a longitudinally unbounded object is verified. The results obtained from this preliminary performance evaluation encourage an expectation of medical applications of the x-ray FPI based CBVCT under the circle-plus-two-arc data acquisition, particularly the application in image-guided interventional procedures and radiotherapy where the movement of a patient table is to be avoided.

  12. On "new massive" 4D gravity

    NASA Astrophysics Data System (ADS)

    Bergshoeff, Eric A.; Fernández-Melgarejo, J. J.; Rosseel, Jan; Townsend, Paul K.

    2012-04-01

    We construct a four-dimensional (4D) gauge theory that propagates, unitarily, the five polarization modes of a massive spin-2 particle. These modes are described by a "dual" graviton gauge potential and the Lagrangian is 4th-order in derivatives. As the construction mimics that of 3D "new massive gravity", we call this 4D model (linearized) "new massive dual gravity". We analyse its massless limit, and discuss similarities to the Eddington-Schrödinger model.

  13. 2D/4D marker-free tumor tracking using 4D CBCT as the reference image

    PubMed Central

    Wang, Mengjiao; Rit, Simon; Delmon, Vivien; Wang, Guangzhi

    2014-01-01

    Tumor motion caused by respiration is an important issue in image guided radiotherapy. A 2D/4D matching method between 4D volumes derived from cone beam computed tomography (CBCT) and 2D fluoroscopic images was implemented to track the tumor motion without the use of implanted markers. In this method, firstly, 3DCBCT and phase-rebinned 4DCBCT are reconstructed from cone beam acquisition. Secondly, 4DCBCT volumes and streak free 3DCBCT volume are combined to improve the image quality of the DRRs. Finally, the 2D/4D matching problem is converted into a 2D/2D matching between incoming projections and DRR images from each phase of the 4DCBCT. The diaphragm is used as a target surrogate for matching instead of using the tumor position directly. This relies on the assumption that if a patient has the same breathing phase and diaphragm position as the reference 4DCBCT, then the tumor position is the same. From the matching results, the phase information, diaphragm position and tumor position at the time of each incoming projection acquisition can be derived. The accuracy of this method was verified using 16 candidate datasets, representing lung and liver applications and 1-minute and 2-minute acquisitions. The criteria for the eligibility of datasets were described: 11 eligible datasets were selected to verify the accuracy of diaphragm tracking, and one eligible dataset was chosen to verify the accuracy of tumor tracking. Diaphragm matching accuracy was 1.88±1.35mm in the isocenter plane, the 2D tumor tracking accuracy was 2.13±1.26mm in the isocenter plane. These features make this method feasible for real-time marker-free tumor motion tracking purpose. PMID:24710793

  14. 2D/4D marker-free tumor tracking using 4D CBCT as the reference image

    NASA Astrophysics Data System (ADS)

    Wang, Mengjiao; Sharp, Gregory C.; Rit, Simon; Delmon, Vivien; Wang, Guangzhi

    2014-05-01

    Tumor motion caused by respiration is an important issue in image-guided radiotherapy. A 2D/4D matching method between 4D volumes derived from cone beam computed tomography (CBCT) and 2D fluoroscopic images was implemented to track the tumor motion without the use of implanted markers. In this method, firstly, 3DCBCT and phase-rebinned 4DCBCT are reconstructed from cone beam acquisition. Secondly, 4DCBCT volumes and a streak-free 3DCBCT volume are combined to improve the image quality of the digitally reconstructed radiographs (DRRs). Finally, the 2D/4D matching problem is converted into a 2D/2D matching between incoming projections and DRR images from each phase of the 4DCBCT. The diaphragm is used as a target surrogate for matching instead of using the tumor position directly. This relies on the assumption that if a patient has the same breathing phase and diaphragm position as the reference 4DCBCT, then the tumor position is the same. From the matching results, the phase information, diaphragm position and tumor position at the time of each incoming projection acquisition can be derived. The accuracy of this method was verified using 16 candidate datasets, representing lung and liver applications and one-minute and two-minute acquisitions. The criteria for the eligibility of datasets were described: 11 eligible datasets were selected to verify the accuracy of diaphragm tracking, and one eligible dataset was chosen to verify the accuracy of tumor tracking. The diaphragm matching accuracy was 1.88 ± 1.35 mm in the isocenter plane and the 2D tumor tracking accuracy was 2.13 ± 1.26 mm in the isocenter plane. These features make this method feasible for real-time marker-free tumor motion tracking purposes.

  15. Reconstruction of a time-averaged midposition CT scan for radiotherapy planning of lung cancer patients using deformable registration

    SciTech Connect

    Wolthaus, J. W. H.; Sonke, J.-J.; Herk, M. van; Damen, E. M. F.

    2008-09-15

    Purpose: lower lobe lung tumors move with amplitudes of up to 2 cm due to respiration. To reduce respiration imaging artifacts in planning CT scans, 4D imaging techniques are used. Currently, we use a single (midventilation) frame of the 4D data set for clinical delineation of structures and radiotherapy planning. A single frame, however, often contains artifacts due to breathing irregularities, and is noisier than a conventional CT scan since the exposure per frame is lower. Moreover, the tumor may be displaced from the mean tumor position due to hysteresis. The aim of this work is to develop a framework for the acquisition of a good quality scan representing all scanned anatomy in the mean position by averaging transformed (deformed) CT frames, i.e., canceling out motion. A nonrigid registration method is necessary since motion varies over the lung. Methods and Materials: 4D and inspiration breath-hold (BH) CT scans were acquired for 13 patients. An iterative multiscale motion estimation technique was applied to the 4D CT scan, similar to optical flow but using image phase (gray-value transitions from bright to dark and vice versa) instead. From the (4D) deformation vector field (DVF) derived, the local mean position in the respiratory cycle was computed and the 4D DVF was modified to deform all structures of the original 4D CT scan to this mean position. A 3D midposition (MidP) CT scan was then obtained by (arithmetic or median) averaging of the deformed 4D CT scan. Image registration accuracy, tumor shape deviation with respect to the BH CT scan, and noise were determined to evaluate the image fidelity of the MidP CT scan and the performance of the technique. Results: Accuracy of the used deformable image registration method was comparable to established automated locally rigid registration and to manual landmark registration (average difference to both methods <0.5 mm for all directions) for the tumor region. From visual assessment, the registration was good

  16. Optimal Methodology of SPECT/CT Acquisition and Processing Technique for 123I-DaTSCAN Neuroimaging

    NASA Astrophysics Data System (ADS)

    Siennicki, Jakub; Bieńkiewicz, Małgorzata; Płachcińska, Anna

    2010-01-01

    The aim of this study was to evaluate the effect of ordered-subset expectation maximization reconstruction algorithm with scatter correction and attenuation correction based on computed tomography maps and to find out the optimum number of subsets and iterations upon image quality for 123I-DaTSCAN neuroimaging. We retrospectively studied SPECT/CT scans of 44 consecutive patients with clinical indications of Parkinson's disease. Images were reconstructed with use of two methods: filtered back projection and OSEM. Image quality was assessed by: striatal binding indices as a measure of contrast and coefficients of variation as a measure of noise. The quality of DaTSCAN images reconstructed with the use of OSEM (4iter/10subs) with reconstruction corrections was superior to that provided by the commonly applied FBP.

  17. SU-D-207-03: Development of 4D-CBCT Imaging System with Dual Source KV X-Ray Tubes

    SciTech Connect

    Nakamura, M; Ishihara, Y; Matsuo, Y; Ueki, N; Iizuka, Y; Mizowaki, T; Hiraoka, M

    2015-06-15

    Purpose: The purposes of this work are to develop 4D-CBCT imaging system with orthogonal dual source kV X-ray tubes, and to determine the imaging doses from 4D-CBCT scans. Methods: Dual source kV X-ray tubes were used for the 4D-CBCT imaging. The maximum CBCT field of view was 200 mm in diameter and 150 mm in length, and the imaging parameters were 110 kV, 160 mA and 5 ms. The rotational angle was 105°, the rotational speed of the gantry was 1.5°/s, the gantry rotation time was 70 s, and the image acquisition interval was 0.3°. The observed amplitude of infrared marker motion during respiration was used to sort each image into eight respiratory phase bins. The EGSnrc/BEAMnrc and EGSnrc/DOSXYZnrc packages were used to simulate kV X-ray dose distributions of 4D-CBCT imaging. The kV X-ray dose distributions were calculated for 9 lung cancer patients based on the planning CT images with dose calculation grid size of 2.5 x 2.5 x 2.5 mm. The dose covering a 2-cc volume of skin (D2cc), defined as the inner 5 mm of the skin surface with the exception of bone structure, was assessed. Results: A moving object was well identified on 4D-CBCT images in a phantom study. Given a gantry rotational angle of 105° and the configuration of kV X-ray imaging subsystems, both kV X-ray fields overlapped at a part of skin surface. The D2cc for the 4D-CBCT scans was in the range 73.8–105.4 mGy. Linear correlation coefficient between the 1000 minus averaged SSD during CBCT scanning and D2cc was −0.65 (with a slope of −0.17) for the 4D-CBCT scans. Conclusion: We have developed 4D-CBCT imaging system with dual source kV X-ray tubes. The total imaging dose with 4D-CBCT scans was up to 105.4 mGy.

  18. 4D-Flow validation, numerical and experimental framework

    NASA Astrophysics Data System (ADS)

    Sansom, Kurt; Liu, Haining; Canton, Gador; Aliseda, Alberto; Yuan, Chun

    2015-11-01

    This work presents a group of assessment metrics of new 4D MRI flow sequences, an imaging modality that allows for visualization of three-dimensional pulsatile flow in the cardiovascular anatomy through time-resolved three-dimensional blood velocity measurements from cardiac-cycle synchronized MRI acquisition. This is a promising tool for clinical assessment but lacks a robust validation framework. First, 4D-MRI flow in a subject's stenotic carotid bifurcation is compared with a patient-specific CFD model using two different boundary condition methods. Second, Particle Image Velocimetry in a patient-specific phantom is used as a benchmark to compare the 4D-MRI in vivo measurements and CFD simulations under the same conditions. Comparison of estimated and measureable flow parameters such as wall shear stress, fluctuating velocity rms, Lagrangian particle residence time, will be discussed, with justification for their biomechanics relevance and the insights they can provide on the pathophysiology of arterial disease: atherosclerosis and intimal hyperplasia. Lastly, the framework is applied to a new sequence to provide a quantitative assessment. A parametric analysis on the carotid bifurcation pulsatile flow conditions will be presented and an accuracy assessment provided.

  19. A 4D Hyperspherical Interpretation of q-Space

    PubMed Central

    Hosseinbor, A. Pasha; Chung, Moo K.; Wu, Yu-Chien; Bendlin, Barbara B.; Alexander, Andrew L.

    2015-01-01

    3D q-space can be viewed as the surface of a 4D hypersphere. In this paper, we seek to develop a 4D hyperspherical interpretation of q-space by projecting it onto a hypersphere and subsequently modeling the q-space signal via 4D hyperspherical harmonics (HSH). Using this orthonormal basis, we derive several well-established q-space indices and numerically estimate the diffusion orientation distribution function (dODF). We also derive the integral transform describing the relationship between the diffusion signal and propagator on a hypersphere. Most importantly, we will demonstrate that for hybrid diffusion imaging (HYDI) acquisitions low order linear expansion of the HSH basis is sufficient to characterize diffusion in neural tissue. In fact, the HSH basis achieves comparable signal and better dODF reconstructions than other well-established methods, such as Bessel Fourier orientation reconstruction (BFOR), using fewer fitting parameters. All in all, this work provides a new way of looking at q-space. PMID:25624043

  20. 4D chromatin dynamics in cycling cells

    PubMed Central

    Strickfaden, Hilmar; Zunhammer, Andreas; van Koningsbruggen, Silvana; Köhler, Daniela

    2010-01-01

    This live cell study of chromatin dynamics in four dimensions (space and time) in cycling human cells provides direct evidence for three hypotheses first proposed by Theodor Boveri in seminal studies of fixed blastomeres from Parascaris equorum embryos: (I) Chromosome territory (CT) arrangements are stably maintained during interphase. (II) Chromosome proximity patterns change profoundly during prometaphase. (III) Similar CT proximity patterns in pairs of daughter nuclei reflect symmetrical chromosomal movements during anaphase and telophase, but differ substantially from the arrangement in mother cell nucleus. Hypothesis I could be confirmed for the majority of interphase cells. A minority, however, showed complex, rotational movements of CT assemblies with large-scale changes of CT proximity patterns, while radial nuclear arrangements were maintained. A new model of chromatin dynamics is proposed. It suggests that long-range DNA-DNA interactions in cell nuclei may depend on a combination of rotational CT movements and locally constrained chromatin movements. PMID:21327076

  1. 4D Bioprinting for Biomedical Applications.

    PubMed

    Gao, Bin; Yang, Qingzhen; Zhao, Xin; Jin, Guorui; Ma, Yufei; Xu, Feng

    2016-09-01

    3D bioprinting has been developed to effectively and rapidly pattern living cells and biomaterials, aiming to create complex bioconstructs. However, placing biocompatible materials or cells into direct contact via bioprinting is necessary but insufficient for creating these constructs. Therefore, '4D bioprinting' has emerged recently, where 'time' is integrated with 3D bioprinting as the fourth dimension, and the printed objects can change their shapes or functionalities when an external stimulus is imposed or when cell fusion or postprinting self-assembly occurs. In this review, we highlight recent developments in 4D bioprinting technology. Additionally, we review the uses of 4D bioprinting in tissue engineering and drug delivery. Finally, we discuss the major roadblocks to this approach, together with possible solutions, to provide future perspectives on this technology. PMID:27056447

  2. Comparison of the effect of simple and complex acquisition trajectories on the 2D SPR and 3D voxelized differences for dedicated breast CT imaging

    NASA Astrophysics Data System (ADS)

    Shah, Jainil P.; Mann, Steve D.; McKinley, Randolph L.; Tornai, Martin P.

    2014-03-01

    The 2D scatter-to-primary (SPR) ratios and 3D voxelized difference volumes were characterized for a cone beam breast CT scanner capable of arbitrary (non-traditional) 3D trajectories. The CT system uses a 30x30cm2 flat panel imager with 197 micron pixellation and a rotating tungsten anode x-ray source with 0.3mm focal spot, with an SID of 70cm. Data were acquired for two cylindrical phantoms (12.5cm and 15cm diameter) filled with three different combinations of water and methanol yielding a range of uniform densities. Projections were acquired with two acquisition trajectories: 1) simple-circular azimuthal orbit with fixed tilt; and 2) saddle orbit following a +/-15° sinusoidal trajectory around the object. Projection data were acquired in 2x2 binned mode. Projections were scatter corrected using a beam stop array method, and the 2D SPR was measured on the projections. The scatter corrected and uncorrected data were then reconstructed individually using an iterative ordered subsets convex algorithm, and the 3D difference volumes were calculated as the absolute difference between the two. Results indicate that the 2D SPR is ~7-15% higher on projections with greatest tilt for the saddle orbit, due to the longer x-ray path length through the volume, compared to the 0° tilt projections. Additionally, the 2D SPR increases with object diameter as well as density. The 3D voxelized difference volumes are an estimate of the scatter contribution to the reconstructed attenuation coefficients on a voxel level. They help visualize minor deficiencies and artifacts in the volumes due to correction methods.

  3. Establishing a framework to implement 4D XCAT Phantom for 4D radiotherapy research

    PubMed Central

    Panta, Raj K.; Segars, Paul; Yin, Fang-Fang; Cai, Jing

    2015-01-01

    Aims To establish a framework to implement the 4D integrated extended cardiac torso (XCAT) digital phantom for 4D radiotherapy (RT) research. Materials and Methods A computer program was developed to facilitate the characterization and implementation of the 4D XCAT phantom. The program can (1) generate 4D XCAT images with customized parameter files; (2) review 4D XCAT images; (3) generate composite images from 4D XCAT images; (4) track motion of selected region-of-interested (ROI); (5) convert XCAT raw binary images into DICOM format; (6) analyse clinically acquired 4DCT images and real-time position management (RPM) respiratory signal. Motion tracking algorithm was validated by comparing with manual method. Major characteristics of the 4D XCAT phantom were studied. Results The comparison between motion tracking and manual measurements of lesion motion trajectory showed a small difference between them (mean difference in motion amplitude: 1.2 mm). The maximum lesion motion decreased nearly linearly (R2 = 0.97) as its distance to the diaphragm (DD) increased. At any given DD, lesion motion amplitude increased nearly linearly (R 2 range: 0.89 to 0.95) as the inputted diaphragm motion increased. For a given diaphragm motion, the lesion motion is independent of the lesion size at any given DD. The 4D XCAT phantom can closely reproduce irregular breathing profile. The end-to-end test showed that clinically comparable treatment plans can be generated successfully based on 4D XCAT images. Conclusions An integrated computer program has been developed to generate, review, analyse, process, and export the 4D XCAT images. A framework has been established to implement the 4D XCAT phantom for 4D RT research. PMID:23361276

  4. Real-time dynamic display of registered 4D cardiac MR and ultrasound images using a GPU

    NASA Astrophysics Data System (ADS)

    Zhang, Q.; Huang, X.; Eagleson, R.; Guiraudon, G.; Peters, T. M.

    2007-03-01

    In minimally invasive image-guided surgical interventions, different imaging modalities, such as magnetic resonance imaging (MRI), computed tomography (CT), and real-time three-dimensional (3D) ultrasound (US), can provide complementary, multi-spectral image information. Multimodality dynamic image registration is a well-established approach that permits real-time diagnostic information to be enhanced by placing lower-quality real-time images within a high quality anatomical context. For the guidance of cardiac procedures, it would be valuable to register dynamic MRI or CT with intraoperative US. However, in practice, either the high computational cost prohibits such real-time visualization of volumetric multimodal images in a real-world medical environment, or else the resulting image quality is not satisfactory for accurate guidance during the intervention. Modern graphics processing units (GPUs) provide the programmability, parallelism and increased computational precision to begin to address this problem. In this work, we first outline our research on dynamic 3D cardiac MR and US image acquisition, real-time dual-modality registration and US tracking. Then we describe image processing and optimization techniques for 4D (3D + time) cardiac image real-time rendering. We also present our multimodality 4D medical image visualization engine, which directly runs on a GPU in real-time by exploiting the advantages of the graphics hardware. In addition, techniques such as multiple transfer functions for different imaging modalities, dynamic texture binding, advanced texture sampling and multimodality image compositing are employed to facilitate the real-time display and manipulation of the registered dual-modality dynamic 3D MR and US cardiac datasets.

  5. 4D-Var Developement at GMAO

    NASA Technical Reports Server (NTRS)

    Pelc, Joanna S.; Todling, Ricardo; Akkraoui, Amal El

    2014-01-01

    The Global Modeling and Assimilation Offce (GMAO) is currently using an IAU-based 3D-Var data assimilation system. GMAO has been experimenting with a 3D-Var-hybrid version of its data assimilation system (DAS) for over a year now, which will soon become operational and it will rapidly progress toward a 4D-EnVar. Concurrently, the machinery to exercise traditional 4DVar is in place and it is desirable to have a comparison of the traditional 4D approach with the other available options, and evaluate their performance in the Goddard Earth Observing System (GEOS) DAS. This work will also explore the possibility for constructing a reduced order model (ROM) to make traditional 4D-Var computationally attractive for increasing model resolutions. Part of the research on ROM will be to search for a suitably acceptable space to carry on the corresponding reduction. This poster illustrates how the IAU-based 4D-Var assimilation compares with our currently used IAU-based 3D-Var.

  6. Clinical evaluation of 4D PET motion compensation strategies for treatment verification in ion beam therapy.

    PubMed

    Gianoli, Chiara; Kurz, Christopher; Riboldi, Marco; Bauer, Julia; Fontana, Giulia; Baroni, Guido; Debus, Jürgen; Parodi, Katia

    2016-06-01

    A clinical trial named PROMETHEUS is currently ongoing for inoperable hepatocellular carcinoma (HCC) at the Heidelberg Ion Beam Therapy Center (HIT, Germany). In this framework, 4D PET-CT datasets are acquired shortly after the therapeutic treatment to compare the irradiation induced PET image with a Monte Carlo PET prediction resulting from the simulation of treatment delivery. The extremely low count statistics of this measured PET image represents a major limitation of this technique, especially in presence of target motion. The purpose of the study is to investigate two different 4D PET motion compensation strategies towards the recovery of the whole count statistics for improved image quality of the 4D PET-CT datasets for PET-based treatment verification. The well-known 4D-MLEM reconstruction algorithm, embedding the motion compensation in the reconstruction process of 4D PET sinograms, was compared to a recently proposed pre-reconstruction motion compensation strategy, which operates in sinogram domain by applying the motion compensation to the 4D PET sinograms. With reference to phantom and patient datasets, advantages and drawbacks of the two 4D PET motion compensation strategies were identified. The 4D-MLEM algorithm was strongly affected by inverse inconsistency of the motion model but demonstrated the capability to mitigate the noise-break-up effects. Conversely, the pre-reconstruction warping showed less sensitivity to inverse inconsistency but also more noise in the reconstructed images. The comparison was performed by relying on quantification of PET activity and ion range difference, typically yielding similar results. The study demonstrated that treatment verification of moving targets could be accomplished by relying on the whole count statistics image quality, as obtained from the application of 4D PET motion compensation strategies. In particular, the pre-reconstruction warping was shown to represent a promising choice when combined with intra

  7. Clinical evaluation of 4D PET motion compensation strategies for treatment verification in ion beam therapy

    NASA Astrophysics Data System (ADS)

    Gianoli, Chiara; Kurz, Christopher; Riboldi, Marco; Bauer, Julia; Fontana, Giulia; Baroni, Guido; Debus, Jürgen; Parodi, Katia

    2016-06-01

    A clinical trial named PROMETHEUS is currently ongoing for inoperable hepatocellular carcinoma (HCC) at the Heidelberg Ion Beam Therapy Center (HIT, Germany). In this framework, 4D PET-CT datasets are acquired shortly after the therapeutic treatment to compare the irradiation induced PET image with a Monte Carlo PET prediction resulting from the simulation of treatment delivery. The extremely low count statistics of this measured PET image represents a major limitation of this technique, especially in presence of target motion. The purpose of the study is to investigate two different 4D PET motion compensation strategies towards the recovery of the whole count statistics for improved image quality of the 4D PET-CT datasets for PET-based treatment verification. The well-known 4D-MLEM reconstruction algorithm, embedding the motion compensation in the reconstruction process of 4D PET sinograms, was compared to a recently proposed pre-reconstruction motion compensation strategy, which operates in sinogram domain by applying the motion compensation to the 4D PET sinograms. With reference to phantom and patient datasets, advantages and drawbacks of the two 4D PET motion compensation strategies were identified. The 4D-MLEM algorithm was strongly affected by inverse inconsistency of the motion model but demonstrated the capability to mitigate the noise-break-up effects. Conversely, the pre-reconstruction warping showed less sensitivity to inverse inconsistency but also more noise in the reconstructed images. The comparison was performed by relying on quantification of PET activity and ion range difference, typically yielding similar results. The study demonstrated that treatment verification of moving targets could be accomplished by relying on the whole count statistics image quality, as obtained from the application of 4D PET motion compensation strategies. In particular, the pre-reconstruction warping was shown to represent a promising choice when combined with intra

  8. R4D Parked on Ramp

    NASA Technical Reports Server (NTRS)

    1956-01-01

    This Photograph taken in 1956 shows the first of three R4D Skytrain aircraft on the ramp behind the NACA High-Speed Flight Station. NACA stood for the National Advisory Committee for Aeronautics, which evolved into the National Aeronautics and Space Administration (NASA) in 1958. The R4D Skytrain was one of the early workhorses for NACA and NASA at Edwards Air Force Base, California, from 1952 to 1984. Designated the R4D by the U.S. Navy, the aircraft was called the C-47 by the U.S. Army and U.S. Air Force and the DC-3 by its builder, Douglas Aircraft. Nearly everyone called it the 'Gooney Bird.' In 1962, Congress consolidated the military-service designations and called all of them the C-47. After that date, the R4D at NASA's Flight Research Center (itself redesignated the Dryden Flight Research Center in 1976) was properly called a C-47. Over the 32 years it was used at Edwards, three different R4D/C-47s were used to shuttle personnel and equipment between NACA/NASA Centers and test locations throughout the country and for other purposes. One purpose was landing on 'dry' lakebeds used as alternate landing sites for the X-15, to determine whether their surfaces were hard (dry) enough for the X-15 to land on in case an emergency occurred after its launch and before it could reach Rogers Dry Lake at Edwards Air Force Base. The R4D/C-47 served a variety of needs, including serving as the first air-tow vehicle for the M2-F1 lifting body (which was built of mahogany plywood). The C-47 (as it was then called) was used for 77 tows before the M2-F1 was retired for more advanced lifting bodies that were dropped from the NASA B-52 'Mothership.' The R4D also served as a research aircraft. It was used to conduct early research on wing-tip-vortex flow visualization as well as checking out the NASA Uplink Control System. The first Gooney Bird was at the NACA High-Speed Flight Research Station (now the Dryden Flight Research Center) from 1952 to 1956 and flew at least one cross

  9. Interactive animation of 4D performance capture.

    PubMed

    Casas, Dan; Tejera, Margara; Guillemaut, Jean-Yves; Hilton, Adrian

    2013-05-01

    A 4D parametric motion graph representation is presented for interactive animation from actor performance capture in a multiple camera studio. The representation is based on a 4D model database of temporally aligned mesh sequence reconstructions for multiple motions. High-level movement controls such as speed and direction are achieved by blending multiple mesh sequences of related motions. A real-time mesh sequence blending approach is introduced, which combines the realistic deformation of previous nonlinear solutions with efficient online computation. Transitions between different parametric motion spaces are evaluated in real time based on surface shape and motion similarity. Four-dimensional parametric motion graphs allow real-time interactive character animation while preserving the natural dynamics of the captured performance. PMID:23492379

  10. Nondipole Effects in Xe 4d Photoemission

    SciTech Connect

    Hemmers, O; Guillemin, R; Wolska, A; Lindle, D W; Rolles, D; Cheng, K T; Johnson, W R; Zhou, H L; Manson, S T

    2004-07-14

    We measured the nondipole parameters for the spin-orbit doublets Xe 4d{sub 5/2} and Xe 4d{sub 3/2} over a photon-energy range from 100 eV to 250 eV at beamline 8.0.1.3 of the Advanced Light Source at the Lawrence Berkeley National Laboratory. Significant nondipole effects are found at relatively low energies as a result of Cooper minima in dipole channels and interchannel coupling in quadrupole channels. Most importantly, sharp disagreement between experiment and theory, when otherwise excellent agreement was expected, has provided the first evidence of satellite two-electron quadrupole photoionization transitions, along with their crucial importance for a quantitatively accurate theory.

  11. 4D image reconstruction for emission tomography

    NASA Astrophysics Data System (ADS)

    Reader, Andrew J.; Verhaeghe, Jeroen

    2014-11-01

    An overview of the theory of 4D image reconstruction for emission tomography is given along with a review of the current state of the art, covering both positron emission tomography and single photon emission computed tomography (SPECT). By viewing 4D image reconstruction as a matter of either linear or non-linear parameter estimation for a set of spatiotemporal functions chosen to approximately represent the radiotracer distribution, the areas of so-called ‘fully 4D’ image reconstruction and ‘direct kinetic parameter estimation’ are unified within a common framework. Many choices of linear and non-linear parameterization of these functions are considered (including the important case where the parameters have direct biological meaning), along with a review of the algorithms which are able to estimate these often non-linear parameters from emission tomography data. The other crucial components to image reconstruction (the objective function, the system model and the raw data format) are also covered, but in less detail due to the relatively straightforward extension from their corresponding components in conventional 3D image reconstruction. The key unifying concept is that maximum likelihood or maximum a posteriori (MAP) estimation of either linear or non-linear model parameters can be achieved in image space after carrying out a conventional expectation maximization (EM) update of the dynamic image series, using a Kullback-Leibler distance metric (comparing the modeled image values with the EM image values), to optimize the desired parameters. For MAP, an image-space penalty for regularization purposes is required. The benefits of 4D and direct reconstruction reported in the literature are reviewed, and furthermore demonstrated with simple simulation examples. It is clear that the future of reconstructing dynamic or functional emission tomography images, which often exhibit high levels of spatially correlated noise, should ideally exploit these 4D

  12. Uniform distribution of projection data for improved reconstruction quality of 4D EPR imaging

    PubMed Central

    Ahmad, Rizwan; Vikram, Deepti S.; Clymer, Bradley; Potter, Lee C.; Deng, Yuanmu; Srinivasan, Parthasarathy; Zweier, Jay L.; Kuppusamy, Periannan

    2008-01-01

    In continuous wave (CW) electron paramagnetic resonance imaging (EPRI), high quality of reconstruction in a limited acquisition time is a high priority. It has been shown for the case of 3D EPRI, that a uniform distribution of the projection data generally enhances reconstruction quality. In this work, we have suggested two data acquisition techniques for which the gradient orientations are more evenly distributed over the 4D acquisition space as compared to the existing methods. The first sampling technique is based on equal solid angle partitioning of 4D space, while the second technique is based on Fekete points estimation in 4D to generate a more uniform distribution of data. After acquisition, filtered backprojection (FBP) is applied to carryout the reconstruction in a single stage. The single-stage reconstruction improves the spatial resolution by eliminating the necessity of data interpolation in multi-stage reconstructions. For the proposed data distributions, the simulations and experimental results indicate a higher fidelity to the true object configuration. Using the uniform distribution, we expect about 50% reduction in the acquisition time over the traditional method of equal linear angle acquisition. PMID:17562375

  13. Impact of 4D image quality on the accuracy of target definition.

    PubMed

    Nielsen, Tine Bjørn; Hansen, Christian Rønn; Westberg, Jonas; Hansen, Olfred; Brink, Carsten

    2016-03-01

    Delineation accuracy of target shape and position depends on the image quality. This study investigates whether the image quality on standard 4D systems has an influence comparable to the overall delineation uncertainty. A moving lung target was imaged using a dynamic thorax phantom on three different 4D computed tomography (CT) systems and a 4D cone beam CT (CBCT) system using pre-defined clinical scanning protocols. Peak-to-peak motion and target volume were registered using rigid registration and automatic delineation, respectively. A spatial distribution of the imaging uncertainty was calculated as the distance deviation between the imaged target and the true target shape. The measured motions were smaller than actual motions. There were volume differences of the imaged target between respiration phases. Imaging uncertainties of >0.4 cm were measured in the motion direction which showed that there was a large distortion of the imaged target shape. Imaging uncertainties of standard 4D systems are of similar size as typical GTV-CTV expansions (0.5-1 cm) and contribute considerably to the target definition uncertainty. Optimising and validating 4D systems is recommended in order to obtain the most optimal imaged target shape. PMID:26577711

  14. Active origami by 4D printing

    NASA Astrophysics Data System (ADS)

    Ge, Qi; Dunn, Conner K.; Qi, H. Jerry; Dunn, Martin L.

    2014-09-01

    Recent advances in three dimensional (3D) printing technology that allow multiple materials to be printed within each layer enable the creation of materials and components with precisely controlled heterogeneous microstructures. In addition, active materials, such as shape memory polymers, can be printed to create an active microstructure within a solid. These active materials can subsequently be activated in a controlled manner to change the shape or configuration of the solid in response to an environmental stimulus. This has been termed 4D printing, with the 4th dimension being the time-dependent shape change after the printing. In this paper, we advance the 4D printing concept to the design and fabrication of active origami, where a flat sheet automatically folds into a complicated 3D component. Here we print active composites with shape memory polymer fibers precisely printed in an elastomeric matrix and use them as intelligent active hinges to enable origami folding patterns. We develop a theoretical model to provide guidance in selecting design parameters such as fiber dimensions, hinge length, and programming strains and temperature. Using the model, we design and fabricate several active origami components that assemble from flat polymer sheets, including a box, a pyramid, and two origami airplanes. In addition, we directly print a 3D box with active composite hinges and program it to assume a temporary flat shape that subsequently recovers to the 3D box shape on demand.

  15. Acquisition with (11)C-choline and (18)F-fluorocholine PET/CT for patients with biochemical recurrence of prostate cancer: a systematic review and meta-analysis.

    PubMed

    von Eyben, Finn E; Kairemo, Kalevi

    2016-07-01

    The objective of the systematic review and meta-analysis was to evaluate whether the choice between two radiotracers, (11)C-choline ((11)C-cho) and (18)F-fluorocholine ((18)F-FCH) for PET/CT, and different acquisition protocols contributed to detect metastases for patients with biochemical recurrence of prostate cancer after radical prostatectomy or radiotherapy. We searched in January 2016 in Pubmed and Embase for articles that had used radiolabeled choline PET/CT in restaging. The meta-analysis evaluated technical and clinical aspects. Across 18 articles 1 219 of 2 213 patients (54.9 %) had a positive radiolabeled PET/CT image. Mean of the mean/median restaging PSA levels was 3.6 ± 2.7 ng/mL (range 0.5-10.7 ng/mL). Six articles with (11)C-cho PET/CT had a radiation activity of 561 ± 122 MBq and it was 293 ± 47 MBq in 12 articles with (18)F-FCH PET/CT. The difference was significant (P = 0.007, t test). Uptake time was 5 min in articles with (11)C-cho PET/CT and it was 29 ± 24 min in articles with (18)F-FCH PET/CT. The difference was significant (P = 0.02, t test). Thereby the detection rates of metastatic sites in articles with (11)C-cho (30 ± 5 %) and (18)F-FCH (39 ± 5 %) did not differ significantly (P = 0.26, t test). In linear regression analyses of the articles, the radiation activity of (11)C-cho and (18)F-FCH was not significantly associated with the detection rate of metastatic sites (P = 0.75 and P = 0.60). Restaging with radiolabeled choline PET/CT detected metastatic sites for patients with biochemical recurrence and PSA levels of 1-10 ng/mL at clinically relevant level. The choice between the two choline radiotracers and different acquisition protocols had no significant impact on detection. PMID:27173771

  16. ICT4D: A Computer Science Perspective

    NASA Astrophysics Data System (ADS)

    Sutinen, Erkki; Tedre, Matti

    The term ICT4D refers to the opportunities of Information and Communication Technology (ICT) as an agent of development. Research in that field is often focused on evaluating the feasibility of existing technologies, mostly of Western or Far East Asian origin, in the context of developing regions. A computer science perspective is complementary to that agenda. The computer science perspective focuses on exploring the resources, or inputs, of a particular context and on basing the design of a technical intervention on the available resources, so that the output makes a difference in the development context. The modus operandi of computer science, construction, interacts with evaluation and exploration practices. An analysis of a contextualized information technology curriculum of Tumaini University in southern Tanzania shows the potential of the computer science perspective for designing meaningful information and communication technology for a developing region.

  17. Controlled Source 4D Seismic Imaging

    NASA Astrophysics Data System (ADS)

    Luo, Y.; Morency, C.; Tromp, J.

    2009-12-01

    Earth's material properties may change after significant tectonic events, e.g., volcanic eruptions, earthquake ruptures, landslides, and hydrocarbon migration. While many studies focus on how to interpret observations in terms of changes in wavespeeds and attenuation, the oil industry is more interested in how we can identify and locate such temporal changes using seismic waves generated by controlled sources. 4D seismic analysis is indeed an important tool to monitor fluid movement in hydrocarbon reservoirs during production, improving fields management. Classic 4D seismic imaging involves comparing images obtained from two subsequent seismic surveys. Differences between the two images tell us where temporal changes occurred. However, when the temporal changes are small, it may be quite hard to reliably identify and characterize the differences between the two images. We propose to back-project residual seismograms between two subsequent surveys using adjoint methods, which results in images highlighting temporal changes. We use the SEG/EAGE salt dome model to illustrate our approach. In two subsequent surveys, the wavespeeds and density within a target region are changed, mimicking possible fluid migration. Due to changes in material properties induced by fluid migration, seismograms recorded in the two surveys differ. By back propagating these residuals, the adjoint images identify the location of the affected region. An important issue involves the nature of model. For instance, are we characterizing only changes in wavespeed, or do we also consider density and attenuation? How many model parameters characterize the model, e.g., is our model isotropic or anisotropic? Is acoustic wave propagation accurate enough or do we need to consider elastic or poroelastic effects? We will investigate how imaging strategies based upon acoustic, elastic and poroelastic simulations affect our imaging capabilities.

  18. Fully 4D list-mode reconstruction applied to respiratory-gated PET scans

    NASA Astrophysics Data System (ADS)

    Grotus, N; Reader, A J; Stute, S; Rosenwald, J C; Giraud, P; Buvat, I

    2009-03-01

    18F-fluoro-deoxy-glucose (18F-FDG) positron emission tomography (PET) is one of the most sensitive and specific imaging modalities for the diagnosis of non-small cell lung cancer. A drawback of PET is that it requires several minutes of acquisition per bed position, which results in images being affected by respiratory blur. Respiratory gating techniques have been developed to deal with respiratory motion in the PET images. However, these techniques considerably increase the level of noise in the reconstructed images unless the acquisition time is increased. The aim of this paper is to evaluate a four-dimensional (4D) image reconstruction algorithm that combines the acquired events in all the gates whilst preserving the motion deblurring. This algorithm was compared to classic ordered subset expectation maximization (OSEM) reconstruction of gated and non-gated images, and to temporal filtering of gated images reconstructed with OSEM. Two datasets were used for comparing the different reconstruction approaches: one involving the NEMA IEC/2001 body phantom in motion, the other obtained using Monte-Carlo simulations of the NCAT breathing phantom. Results show that 4D reconstruction reaches a similar performance in terms of the signal-to-noise ratio (SNR) as non-gated reconstruction whilst preserving the motion deblurring. In particular, 4D reconstruction improves the SNR compared to respiratory-gated images reconstructed with the OSEM algorithm. Temporal filtering of the OSEM-reconstructed images helps improve the SNR, but does not achieve the same performance as 4D reconstruction. 4D reconstruction of respiratory-gated images thus appears as a promising tool to reach the same performance in terms of the SNR as non-gated acquisitions while reducing the motion blur, without increasing the acquisition time.

  19. Parallel Wavefront Analysis for a 4D Interferometer

    NASA Technical Reports Server (NTRS)

    Rao, Shanti R.

    2011-01-01

    This software provides a programming interface for automating data collection with a PhaseCam interferometer from 4D Technology, and distributing the image-processing algorithm across a cluster of general-purpose computers. Multiple instances of 4Sight (4D Technology s proprietary software) run on a networked cluster of computers. Each connects to a single server (the controller) and waits for instructions. The controller directs the interferometer to several images, then assigns each image to a different computer for processing. When the image processing is finished, the server directs one of the computers to collate and combine the processed images, saving the resulting measurement in a file on a disk. The available software captures approximately 100 images and analyzes them immediately. This software separates the capture and analysis processes, so that analysis can be done at a different time and faster by running the algorithm in parallel across several processors. The PhaseCam family of interferometers can measure an optical system in milliseconds, but it takes many seconds to process the data so that it is usable. In characterizing an adaptive optics system, like the next generation of astronomical observatories, thousands of measurements are required, and the processing time quickly becomes excessive. A programming interface distributes data processing for a PhaseCam interferometer across a Windows computing cluster. A scriptable controller program coordinates data acquisition from the interferometer, storage on networked hard disks, and parallel processing. Idle time of the interferometer is minimized. This architecture is implemented in Python and JavaScript, and may be altered to fit a customer s needs.

  20. Opening the Black Box of ICT4D: Advancing Our Understanding of ICT4D Partnerships

    ERIC Educational Resources Information Center

    Park, Sung Jin

    2013-01-01

    The term, Information and Communication Technologies for Development (ICT4D), pertains to programs or projects that strategically use ICTs (e.g. mobile phones, computers, and the internet) as a means toward the socio-economic betterment for the poor in developing contexts. Gaining the political and financial support of the international community…

  1. Feasibility of reduced-dose 3D/4D-DSA using a weighted edge preserving filter

    NASA Astrophysics Data System (ADS)

    Oberstar, Erick L.; Speidel, Michael A.; Davis, Brian J.; Strother, Charles; Mistretta, Charles

    2016-03-01

    A conventional 3D/4D digital subtraction angiogram (DSA) requires two rotational acquisitions (mask and fill) to compute the log-subtracted projections that are used to reconstruct a 3D/4D volume. Since all of the vascular information is contained in the fill acquisition, it is hypothesized that it is possible to reduce the x-ray dose of the mask acquisition substantially and still obtain subtracted projections adequate to reconstruct a 3D/4D volume with noise level comparable to a full dose acquisition. A full dose mask and fill acquisition were acquired from a clinical study to provide a known full dose reference reconstruction. Gaussian noise was added to the mask acquisition to simulate a mask acquisition acquired at 10% relative dose. Noise in the low-dose mask projections was reduced with a weighted edge preserving (WEP) filter designed to preserve bony edges while suppressing noise. 2D log-subtracted projections were computed from the filtered low-dose mask and full-dose fill projections, and then 3D/4D-DSA reconstruction algorithms were applied. Additional bilateral filtering was applied to the 3D volumes. The signal-to-noise ratio measured in the filtered 3D/4D-DSA volumes was compared to the full dose case. The average ratio of filtered low-dose SNR to full-dose SNR was 1.07 for the 3D-DSA and 1.05 for the 4D-DSA, indicating the method is a feasible approach to restoring SNR in DSA scans acquired with a low-dose mask. The method was also tested in a phantom study with full dose fill and 22% dose mask.

  2. Exome Sequencing Identifies PDE4D Mutations as Another Cause of Acrodysostosis

    PubMed Central

    Michot, Caroline; Le Goff, Carine; Goldenberg, Alice; Abhyankar, Avinash; Klein, Céline; Kinning, Esther; Guerrot, Anne-Marie; Flahaut, Philippe; Duncombe, Alice; Baujat, Genevieve; Lyonnet, Stanislas; Thalassinos, Caroline; Nitschke, Patrick; Casanova, Jean-Laurent; Le Merrer, Martine; Munnich, Arnold; Cormier-Daire, Valérie

    2012-01-01

    Acrodysostosis is a rare autosomal-dominant condition characterized by facial dysostosis, severe brachydactyly with cone-shaped epiphyses, and short stature. Moderate intellectual disability and resistance to multiple hormones might also be present. Recently, a recurrent mutation (c.1102C>T [p.Arg368∗]) in PRKAR1A has been identified in three individuals with acrodysostosis and resistance to multiple hormones. After studying ten unrelated acrodysostosis cases, we report here de novo PRKAR1A mutations in five out of the ten individuals (we found c.1102C>T [p.Arg368∗] in four of the ten and c.1117T>C [p.Tyr373His] in one of the ten). We performed exome sequencing in two of the five remaining individuals and selected phosphodiesterase 4D (PDE4D) as a candidate gene. PDE4D encodes a class IV cyclic AMP (cAMP)-specific phosphodiesterase that regulates cAMP concentration. Exome analysis detected heterozygous PDE4D mutations (c.673C>A [p.Pro225Thr] and c.677T>C [p.Phe226Ser]) in these two individuals. Screening of PDE4D identified heterozygous mutations (c.568T>G [p.Ser190Ala] and c.1759A>C [p.Thr587Pro]) in two additional acrodysostosis cases. These mutations occurred de novo in all four cases. The four individuals with PDE4D mutations shared common clinical features, namely characteristic midface and nasal hypoplasia and moderate intellectual disability. Metabolic screening was normal in three of these four individuals. However, resistance to parathyroid hormone and thyrotropin was consistently observed in the five cases with PRKAR1A mutations. Finally, our study further supports the key role of the cAMP signaling pathway in skeletogenesis. PMID:22464250

  3. Exome sequencing identifies PDE4D mutations as another cause of acrodysostosis.

    PubMed

    Michot, Caroline; Le Goff, Carine; Goldenberg, Alice; Abhyankar, Avinash; Klein, Céline; Kinning, Esther; Guerrot, Anne-Marie; Flahaut, Philippe; Duncombe, Alice; Baujat, Genevieve; Lyonnet, Stanislas; Thalassinos, Caroline; Nitschke, Patrick; Casanova, Jean-Laurent; Le Merrer, Martine; Munnich, Arnold; Cormier-Daire, Valérie

    2012-04-01

    Acrodysostosis is a rare autosomal-dominant condition characterized by facial dysostosis, severe brachydactyly with cone-shaped epiphyses, and short stature. Moderate intellectual disability and resistance to multiple hormones might also be present. Recently, a recurrent mutation (c.1102C>T [p.Arg368*]) in PRKAR1A has been identified in three individuals with acrodysostosis and resistance to multiple hormones. After studying ten unrelated acrodysostosis cases, we report here de novo PRKAR1A mutations in five out of the ten individuals (we found c.1102C>T [p.Arg368(∗)] in four of the ten and c.1117T>C [p.Tyr373His] in one of the ten). We performed exome sequencing in two of the five remaining individuals and selected phosphodiesterase 4D (PDE4D) as a candidate gene. PDE4D encodes a class IV cyclic AMP (cAMP)-specific phosphodiesterase that regulates cAMP concentration. Exome analysis detected heterozygous PDE4D mutations (c.673C>A [p.Pro225Thr] and c.677T>C [p.Phe226Ser]) in these two individuals. Screening of PDE4D identified heterozygous mutations (c.568T>G [p.Ser190Ala] and c.1759A>C [p.Thr587Pro]) in two additional acrodysostosis cases. These mutations occurred de novo in all four cases. The four individuals with PDE4D mutations shared common clinical features, namely characteristic midface and nasal hypoplasia and moderate intellectual disability. Metabolic screening was normal in three of these four individuals. However, resistance to parathyroid hormone and thyrotropin was consistently observed in the five cases with PRKAR1A mutations. Finally, our study further supports the key role of the cAMP signaling pathway in skeletogenesis. PMID:22464250

  4. 17 CFR 260.4d-8 - Content.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 17 Commodity and Securities Exchanges 3 2013-04-01 2013-04-01 false Content. 260.4d-8 Section 260.4d-8 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, TRUST INDENTURE ACT OF 1939 Rules Under Section 304 § 260.4d-8 Content. (a)...

  5. 17 CFR 260.4d-8 - Content.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Content. 260.4d-8 Section 260.4d-8 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, TRUST INDENTURE ACT OF 1939 Rules Under Section 304 § 260.4d-8 Content. (a)...

  6. 17 CFR 260.4d-8 - Content.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

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  7. 17 CFR 260.4d-8 - Content.

    Code of Federal Regulations, 2011 CFR

    2012-04-01

    ... 17 Commodity and Securities Exchanges 3 2012-04-01 2012-04-01 false Content. 260.4d-8 Section 260.4d-8 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, TRUST INDENTURE ACT OF 1939 Rules Under Section 304 § 260.4d-8 Content. (a)...

  8. 17 CFR 260.4d-8 - Content.

    Code of Federal Regulations, 2014 CFR

    2011-04-01

    ... 17 Commodity and Securities Exchanges 3 2011-04-01 2011-04-01 false Content. 260.4d-8 Section 260.4d-8 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, TRUST INDENTURE ACT OF 1939 Rules Under Section 304 § 260.4d-8 Content. (a)...

  9. 17 CFR 260.4d-8 - Content.

    Code of Federal Regulations, 2011 CFR

    2005-04-01

    ... 17 Commodity and Securities Exchanges 3 2005-04-01 2005-04-01 false Content. 260.4d-8 Section 260.4d-8 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, TRUST INDENTURE ACT OF 1939 Rules Under Section 304 § 260.4d-8 Content. (a)...

  10. 17 CFR 260.4d-8 - Content.

    Code of Federal Regulations, 2014 CFR

    2000-04-01

    ... 17 Commodity and Securities Exchanges 3 2000-04-01 2000-04-01 false Content. 260.4d-8 Section 260.4d-8 Commodity and Securities Exchanges GENERAL RULES AND REGULATIONS, TRUST INDENTURE ACT OF 1939 Rules Under Section 304 § 260.4d-8 Content. (a) Each application for an order under section 304(d)...

  11. 17 CFR 260.4d-8 - Content.

    Code of Federal Regulations, 2010 CFR

    2015-04-01

    ... 17 Commodity and Securities Exchanges 4 2015-04-01 2015-04-01 false Content. 260.4d-8 Section 260.4d-8 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, TRUST INDENTURE ACT OF 1939 Rules Under Section 304 § 260.4d-8 Content. (a)...

  12. Vessels as 4-D curves: global minimal 4-D paths to extract 3-D tubular surfaces and centerlines.

    PubMed

    Li, Hua; Yezzi, Anthony

    2007-09-01

    In this paper, we propose an innovative approach to the segmentation of tubular structures. This approach combines all of the benefits of minimal path techniques such as global minimizers, fast computation, and powerful incorporation of user input, while also having the capability to represent and detect vessel surfaces directly which so far has been a feature restricted to active contour and surface techniques. The key is to represent the trajectory of a tubular structure not as a 3-D curve but to go up a dimension and represent the entire structure as a 4-D curve. Then we are able to fully exploit minimal path techniques to obtain global minimizing trajectories between two user supplied endpoints in order to reconstruct tubular structures from noisy or low contrast 3-D data without the sensitivity to local minima inherent in most active surface techniques. In contrast to standard purely spatial 3-D minimal path techniques, however, we are able to represent a full tubular surface rather than just a curve which runs through its interior. Our representation also yields a natural notion of a tube's "central curve." We demonstrate and validate the utility of this approach on magnetic resonance (MR) angiography and computed tomography (CT) images of coronary arteries. PMID:17896594

  13. Evaluation of the Elekta Symmetry ™ 4D IGRT system by using a moving lung phantom

    NASA Astrophysics Data System (ADS)

    Shin, Hun-Joo; Kim, Shin-Wook; Kay, Chul Seung; Seo, Jae-Hyuk; Lee, Gi-Woong; Kang, Ki-Mun; Jang, Hong Seok; Kang, Young-nam

    2015-07-01

    Purpose: 4D cone-beam computed tomography (CBCT) is a beneficial tool for the treatment of movable tumors because it can help us to understand where the tumors are actually located and it has a precise treatment plan. However, general CBCT images have a limitation in that they cannot perfectly perform a sophisticated registration. On the other hand, the Symmetry TM 4D image-guided radiation therapy (IGRT) system of Elekta offers a 4D CBCT registration option. In this study, we evaluated the usefulness of Symmetry TM . Method and Materials: Planning CT images of the CIRS moving lung phantom were acquired 4D multi-detector CT (MDCT), and the images were sorted as 10 phases from 0% phase to 90% phase. The thickness of the CT images was 1 mm. Acquired MDCT images were transferred to the contouring software, and a virtual target was generated. A one-arc volumetric-modulated arc therapy (VMAT) plan was performed by using the treatment planning system on the virtual target. Finally, the movement of the phantom was verified by using the XVI Symmetry TM system. Results: The physical movement of the CIRS moving lung phantom was ±10.0 mm in the superiorinferior direction, ±1.0 mm in the lateral direction, and ±2.5 mm in the anterior-posterior direction. The movement of the phantom was measured from the 4D MDCT registration as ±10.2 mm in the superior-inferior direction, ±0.9 mm in the lateral direction, and ±2.45 mm in the anterior-posterior direction. The movement of the phantom was measured from the SymmetryTM registration as ±10.1 mm in the superior-inferior direction, ±0.9 mm in the lateral direction, and ±2.4 mm in the anterior-posterior direction. Conclusion: We confirmed that 4D CBCT is a beneficial tool for the treatment of movable tumors, and that the 4D registration of SymmetryTM can increase the precision of the registration when a movable tumor is the target of radiation treatment.

  14. Novel use of 4D-CTA in imaging of intranidal aneurysms in an acutely ruptured arteriovenous malformation: is this the way forward?

    PubMed

    Chandran, Arun; Radon, Mark; Biswas, Shubhabrata; Das, Kumar; Puthuran, Mani; Nahser, Hans

    2016-09-01

    Ruptured arteriovenous malformation (AVM) is a frequent cause of intracranial hemorrhage. The presence of associated aneurysms, especially intranidal aneurysms, is considered to increase the risk of re-hemorrhage. We present two cases where an intranidal aneurysm was demonstrated on four-dimensional CT angiography (time-resolved CT angiography) (4D-CTA). These features were confirmed by digital subtraction angiography (catheter arterial angiogram). This is the first report of an intranidal aneurysm demonstrated by 4D-CTA. 4D-CTA can offer a comprehensive evaluation of the angioarchitecture and flow dynamics of an AVM for appropriate classification and management. PMID:26180096

  15. Automated contour mapping using sparse volume sampling for 4D radiation therapy

    SciTech Connect

    Chao Ming; Schreibmann, Eduard; Li Tianfang; Wink, Nicole; Xing Lei

    2007-10-15

    The purpose of this work is to develop a novel strategy to automatically map organ contours from one phase of respiration to all other phases on a four-dimensional computed tomography (4D CT). A region of interest (ROI) was manually delineated by a physician on one phase specific image set of a 4D CT. A number of cubic control volumes of the size of {approx}1 cm were automatically placed along the contours. The control volumes were then collectively mapped to the next phase using a rigid transformation. To accommodate organ deformation, a model-based adaptation of the control volume positions was followed after the rigid mapping procedure. This further adjustment of control volume positions was performed by minimizing an energy function which balances the tendency for the control volumes to move to their correspondences with the desire to maintain similar image features and shape integrity of the contour. The mapped ROI surface was then constructed based on the central positions of the control volumes using a triangulated surface construction technique. The proposed technique was assessed using a digital phantom and 4D CT images of three lung patients. Our digital phantom study data indicated that a spatial accuracy better than 2.5 mm is achievable using the proposed technique. The patient study showed a similar level of accuracy. In addition, the computational speed of our algorithm was significantly improved as compared with a conventional deformable registration-based contour mapping technique. The robustness and accuracy of this approach make it a valuable tool for the efficient use of the available spatial-tempo information for 4D simulation and treatment.

  16. TU-F-17A-08: The Relative Accuracy of 4D Dose Accumulation for Lung Radiotherapy Using Rigid Dose Projection Versus Dose Recalculation On Every Breathing Phase

    SciTech Connect

    Lamb, J; Lee, C; Tee, S; Lee, P; Iwamoto, K; Low, D; Valdes, G; Robinson, C

    2014-06-15

    Purpose: To investigate the accuracy of 4D dose accumulation using projection of dose calculated on the end-exhalation, mid-ventilation, or average intensity breathing phase CT scan, versus dose accumulation performed using full Monte Carlo dose recalculation on every breathing phase. Methods: Radiotherapy plans were analyzed for 10 patients with stage I-II lung cancer planned using 4D-CT. SBRT plans were optimized using the dose calculated by a commercially-available Monte Carlo algorithm on the end-exhalation 4D-CT phase. 4D dose accumulations using deformable registration were performed with a commercially available tool that projected the planned dose onto every breathing phase without recalculation, as well as with a Monte Carlo recalculation of the dose on all breathing phases. The 3D planned dose (3D-EX), the 3D dose calculated on the average intensity image (3D-AVE), and the 4D accumulations of the dose calculated on the end-exhalation phase CT (4D-PR-EX), the mid-ventilation phase CT (4D-PR-MID), and the average intensity image (4D-PR-AVE), respectively, were compared against the accumulation of the Monte Carlo dose recalculated on every phase. Plan evaluation metrics relating to target volumes and critical structures relevant for lung SBRT were analyzed. Results: Plan evaluation metrics tabulated using 4D-PR-EX, 4D-PR-MID, and 4D-PR-AVE differed from those tabulated using Monte Carlo recalculation on every phase by an average of 0.14±0.70 Gy, - 0.11±0.51 Gy, and 0.00±0.62 Gy, respectively. Deviations of between 8 and 13 Gy were observed between the 4D-MC calculations and both 3D methods for the proximal bronchial trees of 3 patients. Conclusions: 4D dose accumulation using projection without re-calculation may be sufficiently accurate compared to 4D dose accumulated from Monte Carlo recalculation on every phase, depending on institutional protocols. Use of 4D dose accumulation should be considered when evaluating normal tissue complication

  17. Motion4D-library extended

    NASA Astrophysics Data System (ADS)

    Müller, Thomas

    2011-06-01

    The new version of the Motion4D-library now also includes the integration of a Sachs basis and the Jacobi equation to determine gravitational lensing of pointlike sources for arbitrary spacetimes.New version program summaryProgram title: Motion4D-libraryCatalogue identifier: AEEX_v3_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEEX_v3_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 219 441No. of bytes in distributed program, including test data, etc.: 6 968 223Distribution format: tar.gzProgramming language: C++Computer: All platforms with a C++ compilerOperating system: Linux, WindowsRAM: 61 MbytesClassification: 1.5External routines: Gnu Scientic Library (GSL) (http://www.gnu.org/software/gsl/)Catalogue identifier of previous version: AEEX_v2_0Journal reference of previous version: Comput. Phys. Comm. 181 (2010) 703Does the new version supersede the previous version?: YesNature of problem: Solve geodesic equation, parallel and Fermi-Walker transport in four-dimensional Lorentzian spacetimes. Determine gravitational lensing by integration of Jacobi equation and parallel transport of Sachs basis.Solution method: Integration of ordinary differential equations.Reasons for new version: The main novelty of the current version is the extension to integrate the Jacobi equation and the parallel transport of the Sachs basis along null geodesics. In combination, the change of the cross section of a light bundle and thus the gravitational lensing effect of a spacetime can be determined. Furthermore, we have implemented several new metrics.Summary of revisions: The main novelty of the current version is the integration of the Jacobi equation and the parallel transport of the Sachs basis along null geodesics. The corresponding set of equations readd2xμdλ2=-Γρ

  18. A proposed framework for consensus-based lung tumour volume auto-segmentation in 4D computed tomography imaging

    NASA Astrophysics Data System (ADS)

    Martin, Spencer; Brophy, Mark; Palma, David; Louie, Alexander V.; Yu, Edward; Yaremko, Brian; Ahmad, Belal; Barron, John L.; Beauchemin, Steven S.; Rodrigues, George; Gaede, Stewart

    2015-02-01

    This work aims to propose and validate a framework for tumour volume auto-segmentation based on ground-truth estimates derived from multi-physician input contours to expedite 4D-CT based lung tumour volume delineation. 4D-CT datasets of ten non-small cell lung cancer (NSCLC) patients were manually segmented by 6 physicians. Multi-expert ground truth (GT) estimates were constructed using the STAPLE algorithm for the gross tumour volume (GTV) on all respiratory phases. Next, using a deformable model-based method, multi-expert GT on each individual phase of the 4D-CT dataset was propagated to all other phases providing auto-segmented GTVs and motion encompassing internal gross target volumes (IGTVs) based on GT estimates (STAPLE) from each respiratory phase of the 4D-CT dataset. Accuracy assessment of auto-segmentation employed graph cuts for 3D-shape reconstruction and point-set registration-based analysis yielding volumetric and distance-based measures. STAPLE-based auto-segmented GTV accuracy ranged from (81.51  ±  1.92) to (97.27  ±  0.28)% volumetric overlap of the estimated ground truth. IGTV auto-segmentation showed significantly improved accuracies with reduced variance for all patients ranging from 90.87 to 98.57% volumetric overlap of the ground truth volume. Additional metrics supported these observations with statistical significance. Accuracy of auto-segmentation was shown to be largely independent of selection of the initial propagation phase. IGTV construction based on auto-segmented GTVs within the 4D-CT dataset provided accurate and reliable target volumes compared to manual segmentation-based GT estimates. While inter-/intra-observer effects were largely mitigated, the proposed segmentation workflow is more complex than that of current clinical practice and requires further development.

  19. A study on quantitative analysis of field size and dose by using gating system in 4D conformal radiation treatment

    NASA Astrophysics Data System (ADS)

    Ji, Youn-Sang; Dong, Kyung-Rae; Kim, Chang-Bok; Chung, Woon-Kwan; Cho, Jae-Hwan; Lee, Hae-Kag

    2012-10-01

    This study evaluated the gating-based 4-D conformal radiation therapy (4D-CT) treatment planning by a comparison with the common 3-D conformal radiation therapy (3D-CT) treatment planning and examined the change in treatment field size and dose to the tumors and adjacent normal tissues because an unnecessary dose is also included in the 3-D treatment planning for the radiation treatment of tumors in the chest and abdomen. The 3D-CT and gating-based 4D-CT images were obtained from patients who had undergone radiation treatment for chest and abdomen tumors in the oncology department. After establishing a treatment plan, the CT treatment and planning system were used to measure the change in field size for analysis. A dose volume histogram (DVH) was used to calculate the appropriate dose to planning target volume (PTV) tumors and adjacent normal tissue. The difference in the treatment volume of the chest was 0.6 and 0.83 cm on the X- and Y-axis, respectively, for the gross tumor volume (GTV). Accordingly, the values in the 4D-CT treatment planning were smaller and the dose was more concentrated by 2.7% and 0.9% on the GTV and clinical target volume (CTV), respectively. The normal tissues in the surrounding normal tissues were reduced by 3.0%, 7.2%, 0.4%, 1.7%, 2.6% and 0.2% in the bronchus, chest wall, esophagus, heart, lung and spinal cord, respectively. The difference in the treatment volume of the abdomen was 0.72 cm on the X-axis and 0.51 cm on the Y-axis for the GTV; and 1.06 cm on the X-axis and 1.85 cm on the Y-axis for the PTV. Therefore, the values in the 4D-CT treatment planning were smaller. The dose was concentrated by 6.8% and 4.3% on the GTV and PTV, respectively, whereas the adjacent normal tissues in the cord, Lt. kidney, Rt. kidney, small bowels and whole liver were reduced by 3.2%, 4.2%, 1.5%, 6.2% and 12.7%, respectively. The treatment field size was smaller in volume in the case of the 4D-CT treatment planning. In the DVH, the 4D-CT treatment

  20. 17 CFR 260.4d-8 - Content.

    Code of Federal Regulations, 2011 CFR

    1998-04-01

    ... 17 Commodity and Securities Exchanges 3 1998-04-01 1998-04-01 false Content. 260.4d-8 Section 260.4d-8 GENERAL RULES AND REGULATIONS, TRUST INDENTURE ACT OF 1939 Rules Under Section 304 § 260.4d-8 Content. (a) Each application for an order under section 304(d) of the Act (15 U.S.C. 77ddd(d))...

  1. The 4D-TECS integration for NASA TSRV airplane

    NASA Technical Reports Server (NTRS)

    Kaminer, I.; Oshaughnessy, P. R.

    1989-01-01

    The integration of the Total Energy Control System (TECS) concept with 4D navigation is described. This integration was made to increase the operational capacity of modern aircraft and encourage incorporation of this increased capability with the evolving National Airspace System (NAS). Described herein is: 4D smoothing, the basic concepts of TECS, the spoiler integration concept, an algorithm for nulling out time error, speed and altitude profile modes, manual spoiler implementation, 4D logic, and the results of linear and nonlinear analysis.

  2. Killing Weeds with 2,4-D. Extension Bulletin 389.

    ERIC Educational Resources Information Center

    Lee, Oliver C.

    Discussed is the use of the herbicide 2,4-D. Though written for farmers and agricultural workers, the pamphlet considers turf weed control and use of 2,4-D near ornamental plants. Aspects of the use of this herbicide covered are: (1) the common forms of 2,4-D; (2) plant responses and tolerances to the herbicide; (3) dilution and concentration of…

  3. Pros and cons for C4d as a biomarker.

    PubMed

    Cohen, Danielle; Colvin, Robert B; Daha, Mohamed R; Drachenberg, Cinthia B; Haas, Mark; Nickeleit, Volker; Salmon, Jane E; Sis, Banu; Zhao, Ming-Hui; Bruijn, Jan A; Bajema, Ingeborg M

    2012-04-01

    The introduction of C4d in daily clinical practice in the late nineties aroused an ever-increasing interest in the role of antibody-mediated mechanisms in allograft rejection. As a marker of classical complement activation, C4d made it possible to visualize the direct link between anti-donor antibodies and tissue injury at sites of antibody binding in a graft. With the expanding use of C4d worldwide several limitations of C4d were identified. For instance, in ABO-incompatible transplantations C4d is present in the majority of grafts but this seems to point at 'graft accommodation' rather than antibody-mediated rejection. C4d is now increasingly recognized as a potential biomarker in other fields where antibodies can cause tissue damage, such as systemic autoimmune diseases and pregnancy. In all these fields, C4d holds promise to detect patients at risk for the consequences of antibody-mediated disease. Moreover, the emergence of new therapeutics that block complement activation makes C4d a marker with potential to identify patients who may possibly benefit from these drugs. This review provides an overview of the past, present, and future perspectives of C4d as a biomarker, focusing on its use in solid organ transplantation and discussing its possible new roles in autoimmunity and pregnancy. PMID:22297669

  4. 4D measurement system for automatic location of anatomical structures

    NASA Astrophysics Data System (ADS)

    Witkowski, Marcin; Sitnik, Robert; Kujawińska, Małgorzata; Rapp, Walter; Kowalski, Marcin; Haex, Bart; Mooshake, Sven

    2006-04-01

    Orthopedics and neurosciences are fields of medicine where the analysis of objective movement parameters is extremely important for clinical diagnosis. Moreover, as there are significant differences between static and dynamic parameters, there is a strong need of analyzing the anatomical structures under functional conditions. In clinical gait analysis the benefits of kinematical methods are undoubted. In this paper we present a 4D (3D + time) measurement system capable of automatic location of selected anatomical structures by locating and tracing the structures' position and orientation in time. The presented system is designed to help a general practitioner in diagnosing selected lower limbs' dysfunctions (e.g. knee injuries) and also determine if a patient should be directed for further examination (e.g. x-ray or MRI). The measurement system components are hardware and software. For the hardware part we adapt the laser triangulation method. In this way we can evaluate functional and dynamic movements in a contact-free, non-invasive way, without the use of potentially harmful radiation. Furthermore, opposite to marker-based video-tracking systems, no preparation time is required. The software part consists of a data acquisition module, an image processing and point clouds (point cloud, set of points described by coordinates (x, y, z)) calculation module, a preliminary processing module, a feature-searching module and an external biomechanical module. The paper briefly presents the modules mentioned above with the focus on the feature-searching module. Also we present some measurement and analysis results. These include: parameters maps, landmarks trajectories in time sequence and animation of a simplified model of lower limbs.

  5. Bone scaffolds loaded with siRNA-Semaphorin4d for the treatment of osteoporosis related bone defects

    PubMed Central

    Zhang, Yufeng; Wei, Lingfei; Miron, Richard J.; Shi, Bin; Bian, Zhuan

    2016-01-01

    Osteoporosis is a prominent disorder affecting over 200 million people worldwide. Recently, semaphorins have been implicated in the cell-cell communication between osteoclasts and osteoblasts and have been associated with the progression of osteoporosis. Previously, we demonstrated that knockdown of semaphorin4d (Sema4d) using siRNA delivered with a bone-targeting system prevented bone loss in an osteoporotic animal model. Here, we used this bone-specific technology containing siRNA-Sema4d and fabricated a PLLA scaffold capable of enhancing bone repair following fracture. We investigated the ability of the implant to release siRNA-Sema4d into the surrounding tissues over time and to influence new bone formation in a 3 mm femur osteoporotic defect model in ovariectomized rats. Delivery of the bone-targeting system released from PLLA scaffolds began 2 hours post-implantation, peaked at 1 day, and was sustained over a 21 day period. μCT analysis demonstrated a significantly higher bone volume/total volume bone mineral density and number of osteoblasts in the rats that were transplanted with scaffolds loaded with siRNA-Sema4d. These results confirm the specific role of Sema4d in bone remodeling and demonstrate that significant increases in the speed and quality of new bone formation occur when siRNA-Sema4d is delivered via a PLLA scaffold. PMID:27254469

  6. Bone scaffolds loaded with siRNA-Semaphorin4d for the treatment of osteoporosis related bone defects.

    PubMed

    Zhang, Yufeng; Wei, Lingfei; Miron, Richard J; Shi, Bin; Bian, Zhuan

    2016-01-01

    Osteoporosis is a prominent disorder affecting over 200 million people worldwide. Recently, semaphorins have been implicated in the cell-cell communication between osteoclasts and osteoblasts and have been associated with the progression of osteoporosis. Previously, we demonstrated that knockdown of semaphorin4d (Sema4d) using siRNA delivered with a bone-targeting system prevented bone loss in an osteoporotic animal model. Here, we used this bone-specific technology containing siRNA-Sema4d and fabricated a PLLA scaffold capable of enhancing bone repair following fracture. We investigated the ability of the implant to release siRNA-Sema4d into the surrounding tissues over time and to influence new bone formation in a 3 mm femur osteoporotic defect model in ovariectomized rats. Delivery of the bone-targeting system released from PLLA scaffolds began 2 hours post-implantation, peaked at 1 day, and was sustained over a 21 day period. μCT analysis demonstrated a significantly higher bone volume/total volume bone mineral density and number of osteoblasts in the rats that were transplanted with scaffolds loaded with siRNA-Sema4d. These results confirm the specific role of Sema4d in bone remodeling and demonstrate that significant increases in the speed and quality of new bone formation occur when siRNA-Sema4d is delivered via a PLLA scaffold. PMID:27254469

  7. Direct Visuo-Haptic 4D Volume Rendering Using Respiratory Motion Models.

    PubMed

    Fortmeier, Dirk; Wilms, Matthias; Mastmeyer, Andre; Handels, Heinz

    2015-01-01

    This article presents methods for direct visuo-haptic 4D volume rendering of virtual patient models under respiratory motion. Breathing models are computed based on patient-specific 4D CT image data sequences. Virtual patient models are visualized in real-time by ray casting based rendering of a reference CT image warped by a time-variant displacement field, which is computed using the motion models at run-time. Furthermore, haptic interaction with the animated virtual patient models is provided by using the displacements computed at high rendering rates to translate the position of the haptic device into the space of the reference CT image. This concept is applied to virtual palpation and the haptic simulation of insertion of a virtual bendable needle. To this aim, different motion models that are applicable in real-time are presented and the methods are integrated into a needle puncture training simulation framework, which can be used for simulated biopsy or vessel puncture in the liver. To confirm real-time applicability, a performance analysis of the resulting framework is given. It is shown that the presented methods achieve mean update rates around 2,000 Hz for haptic simulation and interactive frame rates for volume rendering and thus are well suited for visuo-haptic rendering of virtual patients under respiratory motion. PMID:26087498

  8. A method for deriving a 4D-interpolated balanced planning target for mobile tumor radiotherapy

    SciTech Connect

    Roland, Teboh; Hales, Russell; McNutt, Todd; Wong, John; Simari, Patricio; Tryggestad, Erik

    2012-01-15

    Purpose: Tumor control and normal tissue toxicity are strongly correlated to the tumor and normal tissue volumes receiving high prescribed dose levels in the course of radiotherapy. Planning target definition is, therefore, crucial to ensure favorable clinical outcomes. This is especially important for stereotactic body radiation therapy of lung cancers, characterized by high fractional doses and steep dose gradients. The shift in recent years from population-based to patient-specific treatment margins, as facilitated by the emergence of 4D medical imaging capabilities, is a major improvement. The commonly used motion-encompassing, or internal-target volume (ITV), target definition approach provides a high likelihood of coverage for the mobile tumor but inevitably exposes healthy tissue to high prescribed dose levels. The goal of this work was to generate an interpolated balanced planning target that takes into account both tumor coverage and normal tissue sparing from high prescribed dose levels, thereby improving on the ITV approach. Methods: For each 4DCT dataset, 4D deformable image registration was used to derive two bounding targets, namely, a 4D-intersection and a 4D-composite target which minimized normal tissue exposure to high prescribed dose levels and maximized tumor coverage, respectively. Through definition of an ''effective overlap volume histogram'' the authors derived an ''interpolated balanced planning target'' intended to balance normal tissue sparing from prescribed doses with tumor coverage. To demonstrate the dosimetric efficacy of the interpolated balanced planning target, the authors performed 4D treatment planning based on deformable image registration of 4D-CT data for five previously treated lung cancer patients. Two 4D plans were generated per patient, one based on the interpolated balanced planning target and the other based on the conventional ITV target. Plans were compared for tumor coverage and the degree of normal tissue sparing

  9. Automated 4D lung computed tomography reconstruction during free breathing for conformal radiation therapy

    NASA Astrophysics Data System (ADS)

    El Naqa, Issam M.; Low, Daniel A.; Christensen, Gary E.; Parikh, Parag J.; Song, Joo Hyun; Nystrom, Michelle M.; Lu, Wei; Deasy, Joseph O.; Hubenschmidt, James P.; Wahab, Sasha H.; Mutic, Sasa; Singh, Anurag K.; Bradley, Jeffrey D.

    2004-04-01

    We are developing 4D-CT to provide breathing motion information (trajectories) for radiation therapy treatment planning of lung cancer. Potential applications include optimization of intensity-modulated beams in the presence of breathing motion and intra-fraction target volume margin determination for conformal therapy. The images are acquired using a multi-slice CT scanner while the patient undergoes simultaneous quantitative spirometry. At each couch position, the CT scanner is operated in ciné mode and acquires up to 15 scans of 12 slices each. Each CT scan is associated with the measured tidal volume for retrospective reconstruction of 3D CT scans at arbitrary tidal volumes. The specific tasks of this project involves the development of automated registration of internal organ motion (trajectories) during breathing. A modified least-squares based optical flow algorithm tracks specific features of interest by modifying the eigenvalues of gradient matrix (gradient structural tensor). Good correlations between the measured motion and spirometry-based tidal volume are observed and evidence of internal hysteresis is also detected.

  10. SU-D-18C-01: A Novel 4D-MRI Technology Based On K-Space Retrospective Sorting

    SciTech Connect

    Liu, Y; Yin, F; Cai, J

    2014-06-01

    Purpose: Current 4D-MRI techniques lack sufficient temporal/spatial resolution and consistent tumor contrast. To overcome these limitations, this study presents the development and initial evaluation of an entirely new framework of 4D-MRI based on k-space retrospective sorting. Methods: An important challenge of the proposed technique is to determine the number of repeated scans(NR) required to obtain sufficient k-space data for 4D-MRI. To do that, simulations using 29 cancer patients' respiratory profiles were performed to derive the relationship between data acquisition completeness(Cp) and NR, also relationship between NR(Cp=95%) and the following factors: total slice(NS), respiratory phase bin length(Lb), frame rate(fr), resolution(R) and image acquisition starting-phase(P0). To evaluate our technique, a computer simulation study on a 4D digital human phantom (XCAT) were conducted with regular breathing (fr=0.5Hz; R=256×256). A 2D echo planer imaging(EPI) MRI sequence were assumed to acquire raw k-space data, with respiratory signal and acquisition time for each k-space data line recorded simultaneously. K-space data was re-sorted based on respiratory phases. To evaluate 4D-MRI image quality, tumor trajectories were measured and compared with the input signal. Mean relative amplitude difference(D) and cross-correlation coefficient(CC) are calculated. Finally, phase-sharing sliding window technique was applied to investigate the feasibility of generating ultra-fast 4D-MRI. Result: Cp increased with NR(Cp=100*[1-exp(-0.19*NR)], when NS=30, Lb=100%/6). NR(Cp=95%) was inversely-proportional to Lb (r=0.97), but independent of other factors. 4D-MRI on XCAT demonstrated highly accurate motion information (D=0.67%, CC=0.996) with much less artifacts than those on image-based sorting 4D-MRI. Ultra-fast 4D-MRI with an apparent temporal resolution of 10 frames/second was reconstructed using the phase-sharing sliding window technique. Conclusions: A novel 4D

  11. Phosphodiesterase 4D Inhibitors Limit Prostate Cancer Growth Potential

    PubMed Central

    Powers, Ginny L.; Hammer, Kimberly D.P.; Domenech, Maribella; Frantskevich, Katsiaryna; Malinowski, Rita L.; Bushman, Wade; Beebe, David J.; Marker, Paul C.

    2014-01-01

    Phosphodiesterase 4D (PDE4D) has recently been implicated as a proliferation-promoting factor in prostate cancer and is over-expressed in human prostate carcinoma. However, the effects of PDE4D inhibition using pharmacological inhibitors have not been examined in prostate cancer. These studies examined the effects of selective PDE4D inhibitors, NVP-ABE171 and cilomilast, as anti-prostate cancer therapies in both in vitro and in vivo models. The effects of PDE4D inhibitors on pathways that are critical in prostate cancer and/or downstream of cyclic AMP (cAMP) were examined. Both NVP-ABE171 and cilomilast decreased cell growth. In vitro, PDE4D inhibitors lead to decreased signaling of the sonic hedgehog (SHH), Androgen Receptor (AR), and MAPK pathways, but growth inhibition was best correlated to the sonic hedgehog pathway. PDE4D inhibition also reduced proliferation of epithelial cells induced by paracrine signaling from co-cultured stromal cells that had activated hedgehog signaling. In addition, PDE4D inhibitors decreased the weight of the prostate in wild-type mice. Prostate cancer xenografts grown in nude mice that were treated with cilomilast or NVP-ABE171 had decreased wet weight and increased apoptosis compared to vehicle treated controls. These studies suggest the pharmacological inhibition of PDE4D using small molecule inhibitors is an effective option for prostate cancer therapy. Implications PDE4D inhibitors decrease the growth of prostate cancer cells in vivo and in vitro, and PDE4D inhibition has therapeutic potential in prostate cancer. PMID:25149359

  12. Quantifying the image quality and dose reduction of respiratory triggered 4D cone-beam computed tomography with patient-measured breathing

    NASA Astrophysics Data System (ADS)

    Cooper, Benjamin J.; O'Brien, Ricky T.; Kipritidis, John; Shieh, Chun-Chien; Keall, Paul J.

    2015-12-01

    Respiratory triggered four dimensional cone-beam computed tomography (RT 4D CBCT) is a novel technique that uses a patient’s respiratory signal to drive the image acquisition with the goal of imaging dose reduction without degrading image quality. This work investigates image quality and dose using patient-measured respiratory signals for RT 4D CBCT simulations. Studies were performed that simulate a 4D CBCT image acquisition using both the novel RT 4D CBCT technique and a conventional 4D CBCT technique. A set containing 111 free breathing lung cancer patient respiratory signal files was used to create 111 pairs of RT 4D CBCT and conventional 4D CBCT image sets from realistic simulations of a 4D CBCT system using a Rando phantom and the digital phantom, XCAT. Each of these image sets were compared to a ground truth dataset from which a mean absolute pixel difference (MAPD) metric was calculated to quantify the degradation of image quality. The number of projections used in each simulation was counted and was assumed as a surrogate for imaging dose. Based on 111 breathing traces, when comparing RT 4D CBCT with conventional 4D CBCT, the average image quality was reduced by 7.6% (Rando study) and 11.1% (XCAT study). However, the average imaging dose reduction was 53% based on needing fewer projections (617 on average) than conventional 4D CBCT (1320 projections). The simulation studies have demonstrated that the RT 4D CBCT method can potentially offer a 53% saving in imaging dose on average compared to conventional 4D CBCT in simulation studies using a wide range of patient-measured breathing traces with a minimal impact on image quality.

  13. SU-E-J-183: Quantifying the Image Quality and Dose Reduction of Respiratory Triggered 4D Cone-Beam Computed Tomography with Patient- Measured Breathing

    SciTech Connect

    Cooper, B; OBrien, R; Kipritidis, J; Keall, P

    2014-06-01

    Purpose: Respiratory triggered four dimensional cone-beam computed tomography (RT 4D CBCT) is a novel technique that uses a patient's respiratory signal to drive the image acquisition with the goal of imaging dose reduction without degrading image quality. This work investigates image quality and dose using patient-measured respiratory signals for RT 4D CBCT simulations instead of synthetic sinusoidal signals used in previous work. Methods: Studies were performed that simulate a 4D CBCT image acquisition using both the novel RT 4D CBCT technique and a conventional 4D CBCT technique from a database of oversampled Rando phantom CBCT projections. A database containing 111 free breathing lung cancer patient respiratory signal files was used to create 111 RT 4D CBCT and 111 conventional 4D CBCT image datasets from realistic simulations of a 4D RT CBCT system. Each of these image datasets were compared to a ground truth dataset from which a root mean square error (RMSE) metric was calculated to quantify the degradation of image quality. The number of projections used in each simulation is counted and was assumed as a surrogate for imaging dose. Results: Based on 111 breathing traces, when comparing RT 4D CBCT with conventional 4D CBCT the average image quality was reduced by 7.6%. However, the average imaging dose reduction was 53% based on needing fewer projections (617 on average) than conventional 4D CBCT (1320 projections). Conclusion: The simulation studies using a wide range of patient breathing traces have demonstrated that the RT 4D CBCT method can potentially offer a substantial saving of imaging dose of 53% on average compared to conventional 4D CBCT in simulation studies with a minimal impact on image quality. A patent application (PCT/US2012/048693) has been filed which is related to this work.

  14. A design of a DICOM-RT-based tool box for nonrigid 4D dose calculation.

    PubMed

    Wong, Victy Y W; Baker, Colin R; Leung, T W; Tung, Stewart Y

    2016-01-01

    The study was aimed to introduce a design of a DICOM-RT-based tool box to facilitate 4D dose calculation based on deformable voxel-dose registration. The computational structure and the calculation algorithm of the tool box were explicitly discussed in the study. The tool box was written in MATLAB in conjunction with CERR. It consists of five main functions which allow a) importation of DICOM-RT-based 3D dose plan, b) deformable image registration, c) tracking voxel doses along breathing cycle, d) presentation of temporal dose distribution at different time phase, and e) derivation of 4D dose. The efficacy of using the tool box for clinical application had been verified with nine clinical cases on retrospective-study basis. The logistic and the robustness of the tool box were tested with 27 applications and the results were shown successful with no computational errors encountered. In the study, the accumulated dose coverage as a function of planning CT taken at end-inhale, end-exhale, and mean tumor position were assessed. The results indicated that the majority of the cases (67%) achieved maximum target coverage, while the planning CT was taken at the temporal mean tumor position and 56% at the end-exhale position. The comparable results to the literature imply that the studied tool box can be reliable for 4D dose calculation. The authors suggest that, with proper application, 4D dose calculation using deformable registration can provide better dose evaluation for treatment with moving target. PMID:27074476

  15. Marker-free lung tumor trajectory estimation from a cone beam CT sinogram

    NASA Astrophysics Data System (ADS)

    Hugo, Geoffrey D.; Liang, Jian; Yan, Di

    2010-05-01

    An algorithm was developed to estimate the 3D lung tumor position using the projection data forming a cone beam CT sinogram and a template registration method. A pre-existing respiration-correlated CT image was used to generate templates of the target, which were then registered to the individual cone beam CT projections, and estimates of the target position were made for each projection. The registration search region was constrained based on knowledge of the mean tumor position during the cone beam CT scan acquisition. Several template registration algorithms were compared, including correlation coefficient and robust methods such as block correlation, robust correlation coefficient and robust gradient correlation. Robust registration metrics were found to be less sensitive to occlusions such as overlying tissue and the treatment couch. The mean accuracy of the position estimation was 1.4 mm in phantom with a robust registration algorithm. In two research subjects with peripheral tumors, the mean position and mean target excursion were estimated to within 2.0 mm compared to the results obtained with a '4D' registration of 4D image volumes.

  16. 32 CFR 1645.4 - Exclusion from Class 4-D.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... MINISTERS OF RELIGION § 1645.4 Exclusion from Class 4-D. A registrant is excluded from Class 4-D when his... duly ordained minister of religion in accordance with the ceremonial rite or discipline of a church... principles of religion and administer the ordinances of public worship, as embodied in the creed...

  17. 32 CFR 1645.4 - Exclusion from Class 4-D.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... MINISTERS OF RELIGION § 1645.4 Exclusion from Class 4-D. A registrant is excluded from Class 4-D when his... duly ordained minister of religion in accordance with the ceremonial rite or discipline of a church... principles of religion and administer the ordinances of public worship, as embodied in the creed...

  18. 32 CFR 1645.4 - Exclusion from Class 4-D.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... MINISTERS OF RELIGION § 1645.4 Exclusion from Class 4-D. A registrant is excluded from Class 4-D when his... duly ordained minister of religion in accordance with the ceremonial rite or discipline of a church... principles of religion and administer the ordinances of public worship, as embodied in the creed...

  19. 32 CFR 1645.4 - Exclusion from Class 4-D.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... MINISTERS OF RELIGION § 1645.4 Exclusion from Class 4-D. A registrant is excluded from Class 4-D when his... duly ordained minister of religion in accordance with the ceremonial rite or discipline of a church... principles of religion and administer the ordinances of public worship, as embodied in the creed...

  20. 32 CFR 1645.4 - Exclusion from Class 4-D.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... MINISTERS OF RELIGION § 1645.4 Exclusion from Class 4-D. A registrant is excluded from Class 4-D when his... duly ordained minister of religion in accordance with the ceremonial rite or discipline of a church... principles of religion and administer the ordinances of public worship, as embodied in the creed...

  1. Evaluation for Basic Image Qualities Dependence on the Position in XYZ Directions and Acquisition Parameters of the Cone Beam CT for Angiography System with Flat Panel Detector.

    PubMed

    Tsuda, Norisato; Mitsui, Kota; Oda, Shinichiro

    2016-08-01

    The purpose of this study was to investigate the effect of the position in XYZ directions and acquisition parameters on the basic image qualities of for cone beam computed tomography (CBCT) in an angiography system with flat panel detector. The resolution property (modulation transfer function: MTF) and the noise property (Wiener spectrum: WS) of CBCT images in X-Y plane were measured with different acquisition parameters (scan matrix number and projection number) and the effect of the position in XYZ directions. The MTFs with 1024×1024 matrix were higher than those of 512×512 matrix and decreased in the peripheral areas due to the reduction of projection number. The highest and the lowest MTFs were measured at the X-ray tube side and on the detector side of the position in X-Y plane, respectively. The WS-doubled projection number showed about 50% lesser noise level. There were differences in the Wiener spectra (WS) at the position in XYZ directions. We conclude that the resolution and the noise property of CBCT image in X-Y plane showed dependences on the position in XYZ directions and acquisition parameters of the CBCT. PMID:27546079

  2. SU-D-17A-04: The Impact of Audiovisual Biofeedback On Image Quality During 4D Functional and Anatomic Imaging: Results of a Prospective Clinical Trial

    SciTech Connect

    Keall, P; Pollock, S; Yang, J; Diehn, M; Berger, J; Graves, E; Loo, B; Yamamoto, T

    2014-06-01

    Purpose: The ability of audiovisual (AV) biofeedback to improve breathing regularity has not previously been investigated for functional imaging studies. The purpose of this study was to investigate the impact of AV biofeedback on 4D-PET and 4D-CT image quality in a prospective clinical trial. We hypothesized that motion blurring in 4D-PET images and the number of artifacts in 4D-CT images are reduced using AV biofeedback. Methods: AV biofeedback is a real-time, interactive and personalized system designed to help a patient self-regulate his/her breathing using a patient-specific representative waveform and musical guides. In an IRB-approved prospective clinical trial, 4D-PET and 4D-CT images of 10 lung cancer patients were acquired with AV biofeedback (AV) and free breathing (FB). The 4D-PET images in 6 respiratory bins were analyzed for motion blurring by: (1) decrease of GTVPET and (2) increase of SUVmax in 4-DPET compared to 3D-PET. The 4D-CT images were analyzed for artifacts by: (1) comparing normalized cross correlation-based scores (NCCS); and (2) quantifying a visual assessment score (VAS). A two-tailed paired t-test was used to test the hypotheses. Results: The impact of AV biofeedback on 4D-PET and 4D-CT images varied widely between patients, suggesting inconsistent patient comprehension and capability. Overall, the 4D-PET decrease of GTVPET was 2.0±3.0cm3 with AV and 2.3±3.9cm{sup 3} for FB (p=0.61). The 4D-PET increase of SUVmax was 1.6±1.0 with AV and 1.1±0.8 with FB (p=0.002). The 4D-CT NCCS were 0.65±0.27 with AV and 0.60±0.32 for FB (p=0.32). The 4D-CT VAS was 0.0±2.7 (p=ns). Conclusion: A 10-patient study demonstrated a statistically significant reduction of motion blurring of AV over FB for 1/2 functional 4D-PET imaging metrics. No difference between AV and FB was found for 2 anatomic 4D-CT imaging metrics. Future studies will focus on optimizing the human-computer interface and including patient training sessions for improved

  3. 4D motion animation of coronary arteries from rotational angiography

    NASA Astrophysics Data System (ADS)

    Holub, Wolfgang; Rohkohl, Christopher; Schuldhaus, Dominik; Prümmer, Marcus; Lauritsch, Günter; Hornegger, Joachim

    2011-03-01

    Time-resolved 3-D imaging of the heart is a major research topic in the medical imaging community. Recent advances in the interventional cardiac 3-D imaging from rotational angiography (C-arm CT) are now also making 4-D imaging feasible during procedures in the catheter laboratory. State-of-the-art reconstruction algorithms try to estimate the cardiac motion and utilize the motion field to enhance the reconstruction of a stable cardiac phase (diastole). The available data offers a handful of opportunities during interventional procedures, e.g. the ECG-synchronized dynamic roadmapping or the computation and analysis of functional parameters. In this paper we will demonstrate that the motion vector field (MVF) that is output by motion compensated image reconstruction algorithms is in general not directly usable for animation and motion analysis. Dependent on the algorithm different defects are investigated. A primary issue is that the MVF needs to be inverted, i.e. the wrong direction of motion is provided. A second major issue is the non-periodicity of cardiac motion. In algorithms which compute a non-periodic motion field from a single rotation the in depth motion information along viewing direction is missing, since this cannot be measured in the projections. As a result, while the MVF improves reconstruction quality, it is insufficient for motion animation and analysis. We propose an algorithm to solve both problems, i.e. inversion and missing in-depth information in a unified framework. A periodic version of the MVF is approximated. The task is formulated as a linear optimization problem where a parametric smooth motion model based on B-splines is estimated from the MVF. It is shown that the problem can be solved using a sparse QR factorization within a clinical feasible time of less than one minute. In a phantom experiment using the publicly available CAVAREV platform, the average quality of a non-periodic animation could be increased by 39% by applying the

  4. A set of 4D pediatric XCAT reference phantoms for multimodality research

    SciTech Connect

    Norris, Hannah Zhang, Yakun; Bond, Jason; Sturgeon, Gregory M.; Samei, E.; Segars, W. P.; Minhas, Anum; Frush, D.; Tward, Daniel J.; Ratnanather, J. T.; Miller, M. I.

    2014-03-15

    Purpose: The authors previously developed an adult population of 4D extended cardiac-torso (XCAT) phantoms for multimodality imaging research. In this work, the authors develop a reference set of 4D pediatric XCAT phantoms consisting of male and female anatomies at ages of newborn, 1, 5, 10, and 15 years. These models will serve as the foundation from which the authors will create a vast population of pediatric phantoms for optimizing pediatric CT imaging protocols. Methods: Each phantom was based on a unique set of CT data from a normal patient obtained from the Duke University database. The datasets were selected to best match the reference values for height and weight for the different ages and genders according to ICRP Publication 89. The major organs and structures were segmented from the CT data and used to create an initial pediatric model defined using nonuniform rational B-spline surfaces. The CT data covered the entire torso and part of the head. To complete the body, the authors manually added on the top of the head and the arms and legs using scaled versions of the XCAT adult models or additional models created from cadaver data. A multichannel large deformation diffeomorphic metric mapping algorithm was then used to calculate the transform from a template XCAT phantom (male or female 50th percentile adult) to the target pediatric model. The transform was applied to the template XCAT to fill in any unsegmented structures within the target phantom and to implement the 4D cardiac and respiratory models in the new anatomy. The masses of the organs in each phantom were matched to the reference values given in ICRP Publication 89. The new reference models were checked for anatomical accuracy via visual inspection. Results: The authors created a set of ten pediatric reference phantoms that have the same level of detail and functionality as the original XCAT phantom adults. Each consists of thousands of anatomical structures and includes parameterized models

  5. A set of 4D pediatric XCAT reference phantoms for multimodality research

    PubMed Central

    Norris, Hannah; Zhang, Yakun; Bond, Jason; Sturgeon, Gregory M.; Minhas, Anum; Tward, Daniel J.; Ratnanather, J. T.; Miller, M. I.; Frush, D.; Samei, E.; Segars, W. P.

    2014-01-01

    Purpose: The authors previously developed an adult population of 4D extended cardiac-torso (XCAT) phantoms for multimodality imaging research. In this work, the authors develop a reference set of 4D pediatric XCAT phantoms consisting of male and female anatomies at ages of newborn, 1, 5, 10, and 15 years. These models will serve as the foundation from which the authors will create a vast population of pediatric phantoms for optimizing pediatric CT imaging protocols. Methods: Each phantom was based on a unique set of CT data from a normal patient obtained from the Duke University database. The datasets were selected to best match the reference values for height and weight for the different ages and genders according to ICRP Publication 89. The major organs and structures were segmented from the CT data and used to create an initial pediatric model defined using nonuniform rational B-spline surfaces. The CT data covered the entire torso and part of the head. To complete the body, the authors manually added on the top of the head and the arms and legs using scaled versions of the XCAT adult models or additional models created from cadaver data. A multichannel large deformation diffeomorphic metric mapping algorithm was then used to calculate the transform from a template XCAT phantom (male or female 50th percentile adult) to the target pediatric model. The transform was applied to the template XCAT to fill in any unsegmented structures within the target phantom and to implement the 4D cardiac and respiratory models in the new anatomy. The masses of the organs in each phantom were matched to the reference values given in ICRP Publication 89. The new reference models were checked for anatomical accuracy via visual inspection. Results: The authors created a set of ten pediatric reference phantoms that have the same level of detail and functionality as the original XCAT phantom adults. Each consists of thousands of anatomical structures and includes parameterized models

  6. A multi-resolution approach to retrospectively-gated cardiac micro-CT reconstruction

    NASA Astrophysics Data System (ADS)

    Clark, D. P.; Johnson, G. A.; Badea, C. T.

    2014-03-01

    In preclinical research, micro-CT is commonly used to provide anatomical information; however, there is significant interest in using this technology to obtain functional information in cardiac studies. The fastest acquisition in 4D cardiac micro-CT imaging is achieved via retrospective gating, resulting in irregular angular projections after binning the projections into phases of the cardiac cycle. Under these conditions, analytical reconstruction algorithms, such as filtered back projection, suffer from streaking artifacts. Here, we propose a novel, multi-resolution, iterative reconstruction algorithm inspired by robust principal component analysis which prevents the introduction of streaking artifacts, while attempting to recover the highest temporal resolution supported by the projection data. The algorithm achieves these results through a unique combination of the split Bregman method and joint bilateral filtration. We illustrate the algorithm's performance using a contrast-enhanced, 2D slice through the MOBY mouse phantom and realistic projection acquisition and reconstruction parameters. Our results indicate that the algorithm is robust to under sampling levels of only 34 projections per cardiac phase and, therefore, has high potential in reducing both acquisition times and radiation dose. Another potential advantage of the multi-resolution scheme is the natural division of the reconstruction problem into a large number of independent sub-problems which can be solved in parallel. In future work, we will investigate the performance of this algorithm with retrospectively-gated, cardiac micro-CT data.

  7. 4D-Var or Ensemble Kalman Filter

    NASA Astrophysics Data System (ADS)

    Kalnay, E.; Li, H.; Yang, S.; Miyoshi, T.; Ballabrera, J.

    2007-05-01

    We consider the relative advantages of two advanced data assimilation systems, 4D-Var and ensemble Kalman filter (EnKF), currently in use or considered for operational implementation. We explore the impact of tuning assimilation parameters such as the assimilation window length and background error covariance in 4D-Var, the variance inflation in EnKF, and the effect of model errors and reduced observation coverage in both systems. For short assimilation windows EnKF gives more accurate analyses. Both systems reach similar levels of accuracy if long windows are used for 4D-Var, and for infrequent observations, when ensemble perturbations grow nonlinearly and become non-Gaussian, 4D-Var attains lower errors than EnKF. Results obtained with variations of EnKF using operational models and both simulated and real observations are reviewed. A table summarizes the pros and cons of the two methods.

  8. 4-D-Var or ensemble Kalman filter?

    NASA Astrophysics Data System (ADS)

    Kalnay, Eugenia; Li, Hong; Miyoshi, Takemasa; Yang, Shu-Chih; Ballabrera-Poy, Joaquim

    2007-10-01

    We consider the relative advantages of two advanced data assimilation systems, 4-D-Var and ensemble Kalman filter (EnKF), currently in use or under consideration for operational implementation. With the Lorenz model, we explore the impact of tuning assimilation parameters such as the assimilation window length and background error covariance in 4-D-Var, variance inflation in EnKF, and the effect of model errors and reduced observation coverage. For short assimilation windows EnKF gives more accurate analyses. Both systems reach similar levels of accuracy if long windows are used for 4-D-Var. For infrequent observations, when ensemble perturbations grow non-linearly and become non-Gaussian, 4-D-Var attains lower errors than EnKF. If the model is imperfect, the 4-D-Var with long windows requires weak constraint. Similar results are obtained with a quasi-geostrophic channel model. EnKF experiments made with the primitive equations SPEEDY model provide comparisons with 3-D-Var and guidance on model error and `observation localization'. Results obtained using operational models and both simulated and real observations indicate that currently EnKF is becoming competitive with 4-D-Var, and that the experience acquired with each of these methods can be used to improve the other. A table summarizes the pros and cons of the two methods.

  9. Substitutional 4d and 5d impurities in graphene.

    PubMed

    Alonso-Lanza, Tomás; Ayuela, Andrés; Aguilera-Granja, Faustino

    2016-08-21

    We describe the structural and electronic properties of graphene doped with substitutional impurities of 4d and 5d transition metals. The adsorption energies and distances for 4d and 5d metals in graphene show similar trends for the later groups in the periodic table, which are also well-known characteristics of 3d elements. However, along earlier groups the 4d impurities in graphene show very similar adsorption energies, distances and magnetic moments to the 5d ones, which can be related to the influence of the 4d and 5d lanthanide contraction. Surprisingly, within the manganese group, the total magnetic moment of 3 μB for manganese is reduced to 1 μB for technetium and rhenium. We find that compared with 3d elements, the larger size of the 4d and 5d elements causes a high degree of hybridization with the neighbouring carbon atoms, reducing spin splitting in the d levels. It seems that the magnetic adjustment of graphene could be significantly different if 4d or 5d impurities are used instead of 3d impurities. PMID:27439363

  10. 4D in vivo imaging of subpleural lung parenchyma by swept source optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Meissner, S.; Tabuchi, A.; Mertens, M.; Homann, H.; Walther, J.; Kuebler, W. M.; Koch, E.

    2009-07-01

    In this feasibility study we present a method for 4D imaging of healthy and injured subpleural lung tissue in a mouse model. We used triggered swept source optical coherence tomography with an A-scan frequency of 20 kHz to image murine subpleural alveoli during the ventilation cycle. The data acquisition was gated to the pulmonary airway pressure to take one B-scan in each ventilation cycle for different pressure levels. The acquired B-scans were combined offline to one C-scan for each pressure level. Due to the high acquisition rate of the used optical coherence tomography system, we are also able to perform OCT Doppler imaging of the alveolar arterioles. We demonstrated that OCT is a useful tool to investigate the alveolar dynamics in spatial dimensions and to analyze the alveolar blood flow by using Doppler OCT.

  11. 4D PhaseCam(Trade Mark) Capabilities: Modal Analysis and Multiple-Wavelength Mirror Phasing

    NASA Technical Reports Server (NTRS)

    Millerd, James E.; Hayes, John B.; Schmucker, Mark; Eng, Ron (Technical Monitor)

    2002-01-01

    The PhaseCam is a dynamic phase shifting interferometer system manufactured by 4D Technology Corporation that is capable of very fast data acquisition. This rapid acquisition extends the capability of conventional interferometry to enable measurement in unstable environments, the generation of phase movies of surface shape and to facilitate modal analysis of structures. The PhaseCam hardware and software have been modified for MSFC to include synchronous modal optical measurement and analysis. These modifications will be discussed and data presented. The dynamic range of a phase shifting measurement is limited by local slope and pixel sampling to lambda/4 wave steps. Two-wavelength techniques can increase the effective measurement wavelength from microns to tens of centimeters and permit the phasing of mirror segments. A two wavelength PhaseCam will be discussed and measurement results presented.

  12. Quantitative analysis of tomotherapy, linear-accelerator-based 3D conformal radiation therapy, intensity-modulated radiation therapy, and 4D conformal radiation therapy

    NASA Astrophysics Data System (ADS)

    Cho, Jae-Hwan; Lee, Hae-Kag; Dong, Kyung-Rae; Chung, Woon-Kwan; Lee, Jong-Woong; Park, Hoon-Hee

    2012-04-01

    This study quantified, evaluated and analyzed the radiation dose to which tumors and normal tissues were exposed in 3D conformal radiation therapy (CRT), intensity-modulated radiation therapy (IMRT) and tomotherapy by using a dose volume histogram (DVH) that represented the volume dose and the dose distribution of anatomical structures in the evaluation of treatment planning. Furthermore, a comparison was made for the dose to the gross tumor volume (GTV) and the planning target volume (PTV) of organ to be treated based on the change in field size for three- and four-dimensional computed tomography (3D-CT and 4D-CT) (gating based) and in the histogram with a view to proving the usefulness of 4D-CT therapy, which corresponds to respiration-gated radiation therapy. According to the study results, a comparison of 3D CRT, IMRT with a linear accelerator (LINAC), and tomotherapy demonstrated that the GTV of the cranium was higher for tomotherapy than for 3D CRT and IMRT with a LINAC by 5.2% and 4.6%, respectively. The GTV of the neck was higher for tomotherapy than for 3D CRT and IMRT with a LINAC by 6.5% and 2.0%, respectively. The GTV of the pelvis was higher for tomotherapy than for 3D CRT and IMRT with a LINAC by 8.6% and 3.7%, respectively. When the comparison was made for the 3D-CT and the 4D-CT (gating based) treatment equipment, the GTV and the PTV became smaller for 4D-CT treatment planning than for 3D-CT, which could reduce the area in which normal tissues in the surroundings are exposed to an unnecessary radiation dose. In addition, when 4D-CT treatment planning (gating based) was used, the radiation dose could be concentrated on the GTV, CTV or PTV, which meant that the treatment area exceeded that when 3D-CT's treatment planning was used. Moreover, the radiation dose on nearby normal tissues could be reduced. When 4D-CT treatment planning (gating based) was utilized, unnecessary areas that were exposed to a radiation dose could be reduced more than they could

  13. Breathing adapted radiotherapy: a 4D gating software for lung cancer

    PubMed Central

    2011-01-01

    Purpose Physiological respiratory motion of tumors growing in the lung can be corrected with respiratory gating when treated with radiotherapy (RT). The optimal respiratory phase for beam-on may be assessed with a respiratory phase optimizer (RPO), a 4D image processing software developed with this purpose. Methods and Materials Fourteen patients with lung cancer were included in the study. Every patient underwent a 4D-CT providing ten datasets of ten phases of the respiratory cycle (0-100% of the cycle). We defined two morphological parameters for comparison of 4D-CT images in different respiratory phases: tumor-volume to lung-volume ratio and tumor-to-spinal cord distance. The RPO automatized the calculations (200 per patient) of these parameters for each phase of the respiratory cycle allowing to determine the optimal interval for RT. Results Lower lobe lung tumors not attached to the diaphragm presented with the largest motion with breathing. Maximum inspiration was considered the optimal phase for treatment in 4 patients (28.6%). In 7 patients (50%), however, the RPO showed a most favorable volumetric and spatial configuration in phases other than maximum inspiration. In 2 cases (14.4%) the RPO showed no benefit from gating. This tool was not conclusive in only one case. Conclusions The RPO software presented in this study can help to determine the optimal respiratory phase for gated RT based on a few simple morphological parameters. Easy to apply in daily routine, it may be a useful tool for selecting patients who might benefit from breathing adapted RT. PMID:21702952

  14. Soil matrix and macropore biodegradation of 2,4-D

    SciTech Connect

    Pivetz, B.E.; Steenhuis, T.S.

    1995-07-01

    Preferential flow of pesticides in macropores can lead to decreased travel times through the vadose zone and increased groundwater contamination. Macropores, however, may present a favorable environment for biodegradation because of greater oxygen, nutrient, and substrate supply, and higher microbial populations in earthworm burrows, compared to the soil matrix. The biodegradation of 2,4-dichlorophenoxyacetic acid (2,4-D) was measured in macropores and soil matrix of packed soil columns (7.0-cm diam., 10-cm length) and undisturbed cores contained as well-defined artificial macropore and the undisturbed cores contained earthworm-burrow macropores. A 50 {mu}g/L 2,4-D solution was continuously applied to the unsaturated soil surface and breakthrough curves (BTCs) indicating pesticide loss in the effluent were obtained from the soil matrix and macropore flow paths. Biodegradation rates were calculated separately for each flow path by comparing the BTCs to BTCs representing abiotic conditions, and dividing the 2,4-D loss by the travel time through each flow path. The biodegradation rates increased with time in both flow paths, and the final biodegradation rate in the macropore region surpassed that of the matrix, presumably because of increased microbial populations in the macropore. Complete loss of the 2,4-D in both flow paths was observed after continuous application of 2,4-D for 400 h, with maximum column-averaged 2,4-D loss rates of 0.879 {mu}g/(L h) in the matrix and 1.073 {mu}g/(L h) in the macropore. Biodegradation of 2,4-D was also observed in the macropore and matrix regions of the undisturbed soil cores. 19 refs., 7 figs., 2 tabs.

  15. Semaphorin 4D Promotes Skeletal Metastasis in Breast Cancer

    PubMed Central

    Yang, Ying-Hua; Buhamrah, Asma; Schneider, Abraham; Lin, Yi-Ling; Zhou, Hua; Bugshan, Amr; Basile, John R.

    2016-01-01

    Bone density is controlled by interactions between osteoclasts, which resorb bone, and osteoblasts, which deposit it. The semaphorins and their receptors, the plexins, originally shown to function in the immune system and to provide chemotactic cues for axon guidance, are now known to play a role in this process as well. Emerging data have identified Semaphorin 4D (Sema4D) as a product of osteoclasts acting through its receptor Plexin-B1 on osteoblasts to inhibit their function, tipping the balance of bone homeostasis in favor of resorption. Breast cancers and other epithelial malignancies overexpress Sema4D, so we theorized that tumor cells could be exploiting this pathway to establish lytic skeletal metastases. Here, we use measurements of osteoblast and osteoclast differentiation and function in vitro and a mouse model of skeletal metastasis to demonstrate that both soluble Sema4D and protein produced by the breast cancer cell line MDA-MB-231 inhibits differentiation of MC3T3 cells, an osteoblast cell line, and their ability to form mineralized tissues, while Sema4D-mediated induction of IL-8 and LIX/CXCL5, the murine homologue of IL-8, increases osteoclast numbers and activity. We also observe a decrease in the number of bone metastases in mice injected with MDA-MB-231 cells when Sema4D is silenced by RNA interference. These results are significant because treatments directed at suppression of skeletal metastases in bone-homing malignancies usually work by arresting bone remodeling, potentially leading to skeletal fragility, a significant problem in patient management. Targeting Sema4D in these cancers would not affect bone remodeling and therefore could elicit an improved therapeutic result without the debilitating side effects. PMID:26910109

  16. Aortic 18F-FDG PET/CT uptake pattern at 60 min (early) and 180 min (delayed) acquisition in a control population: a visual and semiquantitative comparative analysis.

    PubMed

    Martínez-Rodríguez, Isabel; Del Castillo-Matos, Rosangie; Quirce, Remedios; Banzo, Ignacio; Jiménez-Bonilla, Julio; Martínez-Amador, Nestor; Ibáñez-Bravo, Susana; Lavado-Pérez, Carmen; Bravo-Ferrer, Zully; Carril, José M

    2013-09-01

    18F-Fluoro-2-deoxy-D-glucose (F-FDG) PET/CT acquisition is generally performed 60 min after injection. The normal biodistribution pattern of F-FDG includes activity in the aortic territory due to blood pool activity, which could interfere in the diagnosis of aortic diseases by overlapping the wall uptake. The aim of the study was to evaluate the change over time of F-FDG uptake by the aortic wall and the activity in the lumen in a control population and to establish normal reference values. This prospective study included 15 control patients (mean age: 58.2 years). PET/CT was acquired 60 min (early scan) and 180 min (delayed scan) after an F-FDG injection at a dose of 7 MBq/kg. A visual and semiquantitative analysis of the F-FDG aortic wall uptake was carried out, and lumen activity and the aortic wall to lumen ratio [target-to-background ratio (TBR)] were determined. In the visual analysis all patients showed F-FDG activity at the aortic territory at 60 and 180 min. The pattern of uptake at 60 min was diffuse in all 15 patients (100%), without delineation of the aortic wall uptake; however, at 180 min the uptake pattern of the aortic wall changed to lineal in 14 patients (93.3%). The aortic wall maximum standardized uptake value decreased from 2.07±0.34 to 1.7±0.46 during the delayed acquisition (P=0.0279) and the lumen maximum standardized uptake value decreased highly significantly (1.99±0.35 vs. 1.36±0.32, P=0.0001). Therefore, TBR also increased highly significantly from 1.04±0.06 to 1.25±0.16 (P<0.0001). The high decrease in blood pool activity from 60 to 180 min provides a better delineation of the aortic wall uptake, which corresponds to the normal pattern at that time. The TBR increased significantly at 180 min, and 1.25±0.16 is suggested as the threshold for diagnostic purposes, especially for the diagnosis of vasculitis. PMID:23797272

  17. Tumor control probability and the utility of 4D vs 3D dose calculations for stereotactic body radiotherapy for lung cancer

    SciTech Connect

    Valdes, Gilmer; Robinson, Clifford; Lee, Percy; Morel, Delphine; Low, Daniel; Iwamoto, Keisuke S.; Lamb, James M.

    2015-04-01

    Four-dimensional (4D) dose calculations for lung cancer radiotherapy have been technically feasible for a number of years but have not become standard clinical practice. The purpose of this study was to determine if clinically significant differences in tumor control probability (TCP) exist between 3D and 4D dose calculations so as to inform the decision whether 4D dose calculations should be used routinely for treatment planning. Radiotherapy plans for Stage I-II lung cancer were created for 8 patients. Clinically acceptable treatment plans were created with dose calculated on the end-exhale 4D computed tomography (CT) phase using a Monte Carlo algorithm. Dose was then projected onto the remaining 9 phases of 4D-CT using the Monte Carlo algorithm and accumulated onto the end-exhale phase using commercially available deformable registration software. The resulting dose-volume histograms (DVH) of the gross tumor volume (GTV), planning tumor volume (PTV), and PTV{sub setup} were compared according to target coverage and dose. The PTV{sub setup} was defined as a volume including the GTV and a margin for setup uncertainties but not for respiratory motion. TCPs resulting from these DVHs were estimated using a wide range of alphas, betas, and tumor cell densities. Differences of up to 5 Gy were observed between 3D and 4D calculations for a PTV with highly irregular shape. When the TCP was calculated using the resulting DVHs for fractionation schedules typically used in stereotactic body radiation therapy (SBRT), the TCP differed at most by 5% between 4D and 3D cases, and in most cases, it was by less than 1%. We conclude that 4D dose calculations are not necessary for most cases treated with SBRT, but they might be valuable for irregularly shaped target volumes. If 4D calculations are used, 4D DVHs should be evaluated on volumes that include margin for setup uncertainty but not respiratory motion.

  18. Scatter correction of vessel dropout behind highly attenuating structures in 4D-DSA

    NASA Astrophysics Data System (ADS)

    Hermus, James; Mistretta, Charles; Szczykutowicz, Timothy P.

    2015-03-01

    In Computed Tomographic (CT) image reconstruction for 4 dimensional digital subtraction angiography (4D-DSA), loss of vessel contrast has been observed behind highly attenuating anatomy, such as large contrast filled aneurysms. Although this typically occurs only in a limited range of projection angles, the observed contrast time course can be altered. In this work we propose an algorithm to correct for highly attenuating anatomy within the fill projection data, i.e. aneurysms. The algorithm uses a 3D-SA volume to create a correction volume that is multiplied by the 4D-DSA volume in order to correct for signal dropout within the 4D-DSA volume. The algorithm was designed to correct for highly attenuating material in the fill volume only, however with alterations to a single step of the algorithm, artifacts due to highly attenuating materials in the mask volume (i.e. dental implants) can be mitigated as well. We successfully applied our algorithm to a case of vessel dropout due to the presence of a large attenuating aneurysm. The performance was qualified visually as the affected vessel no longer dropped out on corrected 4D-DSA time frames. The correction was quantified by plotting the signal intensity along the vessel. Our analysis demonstrated our correction does not alter vessel signal values outside of the vessel dropout region but does increase the vessel values within the dropout region as expected. We have demonstrated that this correction algorithm acts to correct vessel dropout in areas with highly attenuating materials.

  19. New C4D Sensor with a Simulated Inductor

    PubMed Central

    Lyu, Yingchao; Ji, Haifeng; Yang, Shijie; Huang, Zhiyao; Wang, Baoliang; Li, Haiqing

    2016-01-01

    A new capacitively coupled contactless conductivity detection (C4D) sensor with an improved simulated inductor is developed in this work. The improved simulated inductor is designed on the basis of the Riordan-type floating simulated inductor. With the improved simulated inductor, the negative influence of the coupling capacitances is overcome and the conductivity measurement is implemented by the series resonance principle. The conductivity measurement experiments are carried out in three pipes with different inner diameters of 3.0 mm, 4.6 mm and 6.4 mm, respectively. The experimental results show that the designs of the new C4D sensor and the improved simulated inductor are successful. The maximum relative error of the conductivity measurement is less than 5%. Compared with the C4D sensors using practical inductors, the measurement accuracy of the new C4D sensor is comparable. The research results also indicate that the adjustability of a simulated inductor can reduce the requirement for the AC source and guarantee the interchangeableness. Meanwhile, it is recommended that making the potential of one terminal of a simulated inductor stable is beneficial to the running stability. Furthermore, this work indirectly verifies the possibility and feasibility of the miniaturization of the C4D sensor by using the simulated inductor technique and lays a good foundation for future research work. PMID:26828493

  20. Spiral CT: vascular applications.

    PubMed

    Rankin, S C

    1998-08-01

    Recent technical advances in CT have renewed interest in the development of CT angiography (CTA). CT angiography is a minimally invasive method of visualising the vascular system and is becoming an alternative to conventional arteriography in some situations. Spiral technology allows a volume of data to be obtained on a single breath-hold with no respiratory misregistration. Fast machines with second or subsecond acquisition times mean the images are obtained while there are high circulating levels of contrast medium giving peak vascular opacification from a peripheral intravenous injection. Accurate timing will ensure either the arterial or venous phase is imaged. Multiple overlapping axial images can be obtained from the data set with no increase in radiation dose to the patient and from these scans computer generated multiplanar and 3D images are obtained which can be viewed from numerous angles. CT angiography can be performed more quickly, less invasively and at reduced cost compared to conventional angiography. PMID:9717621

  1. SU-E-J-200: A Dosimetric Analysis of 3D Versus 4D Image-Based Dose Calculation for Stereotactic Body Radiation Therapy in Lung Tumors

    SciTech Connect

    Ma, M; Rouabhi, O; Flynn, R; Xia, J; Bayouth, J

    2014-06-01

    Purpose: To evaluate the dosimetric difference between 3D and 4Dweighted dose calculation using patient specific respiratory trace and deformable image registration for stereotactic body radiation therapy in lung tumors. Methods: Two dose calculation techniques, 3D and 4D-weighed dose calculation, were used for dosimetric comparison for 9 lung cancer patients. The magnitude of the tumor motion varied from 3 mm to 23 mm. Breath-hold exhale CT was used for 3D dose calculation with ITV generated from the motion observed from 4D-CT. For 4D-weighted calculation, dose of each binned CT image from the ten breathing amplitudes was first recomputed using the same planning parameters as those used in the 3D calculation. The dose distribution of each binned CT was mapped to the breath-hold CT using deformable image registration. The 4D-weighted dose was computed by summing the deformed doses with the temporal probabilities calculated from their corresponding respiratory traces. Dosimetric evaluation criteria includes lung V20, mean lung dose, and mean tumor dose. Results: Comparing with 3D calculation, lung V20, mean lung dose, and mean tumor dose using 4D-weighted dose calculation were changed by −0.67% ± 2.13%, −4.11% ± 6.94% (−0.36 Gy ± 0.87 Gy), −1.16% ± 1.36%(−0.73 Gy ± 0.85 Gy) accordingly. Conclusion: This work demonstrates that conventional 3D dose calculation method may overestimate the lung V20, MLD, and MTD. The absolute difference between 3D and 4D-weighted dose calculation in lung tumor may not be clinically significant. This research is supported by Siemens Medical Solutions USA, Inc and Iowa Center for Research By Undergraduates.

  2. A LabVIEW Platform for Preclinical Imaging Using Digital Subtraction Angiography and Micro-CT

    PubMed Central

    Badea, Cristian T.; Hedlund, Laurence W.; Johnson, G. Allan

    2013-01-01

    CT and digital subtraction angiography (DSA) are ubiquitous in the clinic. Their preclinical equivalents are valuable imaging methods for studying disease models and treatment. We have developed a dual source/detector X-ray imaging system that we have used for both micro-CT and DSA studies in rodents. The control of such a complex imaging system requires substantial software development for which we use the graphical language LabVIEW (National Instruments, Austin, TX, USA). This paper focuses on a LabVIEW platform that we have developed to enable anatomical and functional imaging with micro-CT and DSA. Our LabVIEW applications integrate and control all the elements of our system including a dual source/detector X-ray system, a mechanical ventilator, a physiological monitor, and a power microinjector for the vascular delivery of X-ray contrast agents. Various applications allow cardiac- and respiratory-gated acquisitions for both DSA and micro-CT studies. Our results illustrate the application of DSA for cardiopulmonary studies and vascular imaging of the liver and coronary arteries. We also show how DSA can be used for functional imaging of the kidney. Finally, the power of 4D micro-CT imaging using both prospective and retrospective gating is shown for cardiac imaging. PMID:27006920

  3. Dose equations for shift-variant CT acquisition modes using variable pitch, tube current, and aperture, and the meaning of their associated CTDI{sub vol}

    SciTech Connect

    Dixon, Robert L.; Boone, John M.; Kraft, Robert A.

    2014-11-01

    Purpose: With the increasing clinical use of shift-variant CT protocols involving tube current modulation (TCM), variable pitch or pitch modulation (PM), and variable aperture a(t), the interpretation of the scanner-reported CTDI{sub vol} is called into question. This was addressed for TCM in their previous paper published by Dixon and Boone [Med. Phys. 40, 111920 (14pp.) (2013)] and is extended to PM and concurrent TCM/PM as well as variable aperture in this work. Methods: Rigorous convolution equations are derived to describe the accumulated dose distributions for TCM, PM, and concurrent TCM/PM. A comparison with scanner-reported CTDI{sub vol} formulae clearly identifies the source of their differences with the traditional CTDI{sub vol}. Dose distribution simulations using the convolution are provided for a variety of TCM and PM scenarios including a helical shuttle used for perfusion studies (as well as constant mA)—all having the same scanner-reported CTDI{sub vol}. These new convolution simulations for TCM are validated by comparison with their previous discrete summations. Results: These equations show that PM is equivalent to TCM if the pitch variation p(z) is proportional to 1/i(z), where i(z) is the local tube current. The simulations show that the local dose at z depends only weakly on the local tube current i(z) or local pitch p(z) due to scatter from all other locations along z, and that the “local CTDI{sub vol}(z)” or “CTDI{sub vol} per slice” do not represent a local dose but rather only a relative i(z) or p(z). The CTDI-paradigm does not apply to shift-variant techniques and the scanner-reported CTDI{sub vol} for the same lacks physical significance and relevance. Conclusions: While the traditional CTDI{sub vol} at constant tube current and pitch conveys useful information (the peak dose at the center of the scan length), CTDI{sub vol} for shift-variant techniques (TCM or PM) conveys no useful information about the associated dose

  4. Model-driven physiological assessment of the mitral valve from 4D TEE

    NASA Astrophysics Data System (ADS)

    Voigt, Ingmar; Ionasec, Razvan Ioan; Georgescu, Bogdan; Houle, Helene; Huber, Martin; Hornegger, Joachim; Comaniciu, Dorin

    2009-02-01

    Disorders of the mitral valve are second most frequent, cumulating 14 percent of total number of deaths caused by Valvular Heart Disease each year in the United States and require elaborate clinical management. Visual and quantitative evaluation of the valve is an important step in the clinical workflow according to experts as knowledge about mitral morphology and dynamics is crucial for interventional planning. Traditionally this involves examination and metric analysis of 2D images comprising potential errors being intrinsic to the method. Recent commercial solutions are limited to specific anatomic components, pathologies and a single phase of cardiac 4D acquisitions only. This paper introduces a novel approach for morphological and functional quantification of the mitral valve based on a 4D model estimated from ultrasound data. A physiological model of the mitral valve, covering the complete anatomy and eventual shape variations, is generated utilizing parametric spline surfaces constrained by topological and geometrical prior knowledge. The 4D model's parameters are estimated for each patient using the latest discriminative learning and incremental searching techniques. Precise evaluation of the anatomy using model-based dynamic measurements and advanced visualization are enabled through the proposed approach in a reliable, repeatable and reproducible manner. The efficiency and accuracy of the method is demonstrated through experiments and an initial validation based on clinical research results. To the best of our knowledge this is the first time such a patient specific 4D mitral valve model is proposed, covering all of the relevant anatomies and enabling to model the common pathologies at once.

  5. High temporal and high spatial resolution MR angiography (4D-MRA).

    PubMed

    Hadizadeh, D R; Marx, C; Gieseke, J; Schild, H H; Willinek, W A

    2014-09-01

    In the first decade of the twenty-first century, whole-body magnetic resonance scanners with high field strengths (and thus potentially better signal-to-noise ratios) were developed. At the same time, parallel imaging and "echo-sharing" techniques were refined to allow for increasingly high spatial and temporal resolution in dynamic magnetic resonance angiography ("time-resolved" = TR-MRA). This technological progress facilitated tracking the passage of intra-venously administered contrast agent boluses as well as the acquisition of volume data sets at high image refresh rates ("4D-MRA"). This opened doors for many new applications in non-invasive vascular imaging, including simultaneous anatomic and functional analysis of many vascular pathologies including arterio-venous malformations. Different methods were established to acquire 4D-MRA using various strategies to acquire k-space trajectories over time in order to optimize imaging according to clinical needs. These include "keyhole"-based techniques (e. g. 4D-TRAK), TRICKS - both with and without projection - and HYPR-reconstruction, TREAT, and TWIST. Some of these techniques were first introduced in the 1980 s and 1990 s, were later enhanced and modified, and finally implemented in the products of major vendors. In the last decade, a large number of studies on the clinical applications of TR-MRA was published. This manuscript provides an overview of the development of TR-MRA methods and the 4D-MRA techniques as they are currently used in the diagnosis, treatment and follow-up of vascular diseases in various parts of the body. PMID:24955647

  6. 4D cone beam CT-based dose assessment for SBRT lung cancer treatment

    NASA Astrophysics Data System (ADS)

    Cai, Weixing; Dhou, Salam; Cifter, Fulya; Myronakis, Marios; Hurwitz, Martina H.; Williams, Christopher L.; Berbeco, Ross I.; Seco, Joao; Lewis, John H.

    2016-01-01

    The purpose of this research is to develop a 4DCBCT-based dose assessment method for calculating actual delivered dose for patients with significant respiratory motion or anatomical changes during the course of SBRT. To address the limitation of 4DCT-based dose assessment, we propose to calculate the delivered dose using time-varying (‘fluoroscopic’) 3D patient images generated from a 4DCBCT-based motion model. The method includes four steps: (1) before each treatment, 4DCBCT data is acquired with the patient in treatment position, based on which a patient-specific motion model is created using a principal components analysis algorithm. (2) During treatment, 2D time-varying kV projection images are continuously acquired, from which time-varying ‘fluoroscopic’ 3D images of the patient are reconstructed using the motion model. (3) Lateral truncation artifacts are corrected using planning 4DCT images. (4) The 3D dose distribution is computed for each timepoint in the set of 3D fluoroscopic images, from which the total effective 3D delivered dose is calculated by accumulating deformed dose distributions. This approach is validated using six modified XCAT phantoms with lung tumors and different respiratory motions derived from patient data. The estimated doses are compared to that calculated using ground-truth XCAT phantoms. For each XCAT phantom, the calculated delivered tumor dose values generally follow the same trend as that of the ground truth and at most timepoints the difference is less than 5%. For the overall delivered dose, the normalized error of calculated 3D dose distribution is generally less than 3% and the tumor D95 error is less than 1.5%. XCAT phantom studies indicate the potential of the proposed method to accurately estimate 3D tumor dose distributions for SBRT lung treatment based on 4DCBCT imaging and motion modeling. Further research is necessary to investigate its performance for clinical patient data.

  7. 4D Near Real-Time Environmental Monitoring Using Highly Temporal LiDAR

    NASA Astrophysics Data System (ADS)

    Höfle, Bernhard; Canli, Ekrem; Schmitz, Evelyn; Crommelinck, Sophie; Hoffmeister, Dirk; Glade, Thomas

    2016-04-01

    The last decade has witnessed extensive applications of 3D environmental monitoring with the LiDAR technology, also referred to as laser scanning. Although several automatic methods were developed to extract environmental parameters from LiDAR point clouds, only little research has focused on highly multitemporal near real-time LiDAR (4D-LiDAR) for environmental monitoring. Large potential of applying 4D-LiDAR is given for landscape objects with high and varying rates of change (e.g. plant growth) and also for phenomena with sudden unpredictable changes (e.g. geomorphological processes). In this presentation we will report on the most recent findings of the research projects 4DEMON (http://uni-heidelberg.de/4demon) and NoeSLIDE (https://geomorph.univie.ac.at/forschung/projekte/aktuell/noeslide/). The method development in both projects is based on two real-world use cases: i) Surface parameter derivation of agricultural crops (e.g. crop height) and ii) change detection of landslides. Both projects exploit the "full history" contained in the LiDAR point cloud time series. One crucial initial step of 4D-LiDAR analysis is the co-registration over time, 3D-georeferencing and time-dependent quality assessment of the LiDAR point cloud time series. Due to the high amount of datasets (e.g. one full LiDAR scan per day), the procedure needs to be performed fully automatically. Furthermore, the online near real-time 4D monitoring system requires to set triggers that can detect removal or moving of tie reflectors (used for co-registration) or the scanner itself. This guarantees long-term data acquisition with high quality. We will present results from a georeferencing experiment for 4D-LiDAR monitoring, which performs benchmarking of co-registration, 3D-georeferencing and also fully automatic detection of events (e.g. removal/moving of reflectors or scanner). Secondly, we will show our empirical findings of an ongoing permanent LiDAR observation of a landslide (Gresten

  8. SU-E-J-26: A Novel Technique for Markerless Self-Sorted 4D-CBCT Using Patient Motion Modeling: A Feasibility Study

    SciTech Connect

    Zhang, L; Zhang, Y; Harris, W; Yin, F; Ren, L

    2015-06-15

    Purpose: To develop an automatic markerless 4D-CBCT projection sorting technique by using a patient respiratory motion model extracted from the planning 4D-CT images. Methods: Each phase of onboard 4D-CBCT is considered as a deformation of one phase of the prior planning 4D-CT. The deformation field map (DFM) is represented as a linear combination of three major deformation patterns extracted from the planning 4D-CT using principle component analysis (PCA). The coefficients of the PCA deformation patterns are solved by matching the digitally reconstructed radiograph (DRR) of the deformed volume to the onboard projection acquired. The PCA coefficients are solved for each single projection, and are used for phase sorting. Projections at the peaks of the Z direction coefficient are sorted as phase 1 and other projections are assigned into 10 phase bins by dividing phases equally between peaks. The 4D digital extended-cardiac-torso (XCAT) phantom was used to evaluate the proposed technique. Three scenarios were simulated, with different tumor motion amplitude (3cm to 2cm), tumor spatial shift (8mm SI), and tumor body motion phase shift (2 phases) from prior to on-board images. Projections were simulated over 180 degree scan-angle for the 4D-XCAT. The percentage of accurately binned projections across entire dataset was calculated to represent the phase sorting accuracy. Results: With a changed tumor motion amplitude from 3cm to 2cm, markerless phase sorting accuracy was 100%. With a tumor phase shift of 2 phases w.r.t. body motion, the phase sorting accuracy was 100%. With a tumor spatial shift of 8mm in SI direction, phase sorting accuracy was 86.1%. Conclusion: The XCAT phantom simulation results demonstrated that it is feasible to use prior knowledge and motion modeling technique to achieve markerless 4D-CBCT phase sorting. National Institutes of Health Grant No. R01-CA184173 Varian Medical System.

  9. Relative charge transfer cross section from Rb (4d)

    NASA Astrophysics Data System (ADS)

    Shah, M. H.; Camp, H. A.; Trachy, M. L.; Fléchard, X.; Gearba, M. A.; Nguyen, H.; Brédy, R.; Lundeen, S. R.; Depaola, B. D.

    2005-08-01

    Relative charge transfer cross section measurements for the excited state Rb(4d) with 7keV Na+ is reported. The specific channels reported are Na++Rb(4d5/2)→Na(nl)+Rb+ , where the dominant transfer cross sections channels were nl=3d and 4s . Using a combination of a magneto-optical trap and recoil ion momentum spectroscopy (MOTRIMS methodology), the cross sections were measured relative to the previously studied Na++Rb(5s,5p) systems at the same collision energy.

  10. Relative charge transfer cross section from Rb(4d)

    SciTech Connect

    Shah, M.H.; Camp, H.A.; Trachy, M.L.; De Paola, B.D.; Flechard, X.; Gearba, M.A.; Nguyen, H.; Bredy, R.; Lundeen, S.R.

    2005-08-15

    Relative charge transfer cross section measurements for the excited state Rb(4d) with 7 keV Na{sup +} is reported. The specific channels reported are Na{sup +}+Rb(4d{sub 5/2}){yields}Na(nl)+Rb{sup +}, where the dominant transfer cross sections channels were nl=3d and 4s. Using a combination of a magneto-optical trap and recoil ion momentum spectroscopy (MOTRIMS methodology), the cross sections were measured relative to the previously studied Na{sup +}+Rb(5s,5p) systems at the same collision energy.

  11. The 4-D approach to visual control of autonomous systems

    NASA Technical Reports Server (NTRS)

    Dickmanns, Ernst D.

    1994-01-01

    Development of a 4-D approach to dynamic machine vision is described. Core elements of this method are spatio-temporal models oriented towards objects and laws of perspective projection in a foward mode. Integration of multi-sensory measurement data was achieved through spatio-temporal models as invariants for object recognition. Situation assessment and long term predictions were allowed through maintenance of a symbolic 4-D image of processes involving objects. Behavioral capabilities were easily realized by state feedback and feed-foward control.

  12. Emerging Applications of Abdominal 4D Flow MRI

    PubMed Central

    Roldán-Alzate, Alejandro; Francois, Christopher J.; Wieben, Oliver; Reeder, Scott B.

    2016-01-01

    OBJECTIVE Comprehensive assessment of abdominal hemodynamics is crucial for many clinical diagnoses but is challenged by a tremendous complexity of anatomy, normal physiology, and a wide variety of pathologic abnormalities. This article introduces 4D flow MRI as a powerful technique for noninvasive assessment of the hemodynamics of abdominal vascular territories. CONCLUSION Four-dimensional flow MRI provides clinicians with a more extensive and straightforward approach to evaluate disorders that affect blood flow in the abdomen. This review presents a series of clinical cases to illustrate the utility of 4D flow MRI in the comprehensive assessment of the abdominal circulation. PMID:27187681

  13. Dosimetric impact of motion in free-breathing and gated lung radiotherapy: A 4D Monte Carlo study of intrafraction and interfraction effects

    PubMed Central

    Seco, Joao; Sharp, Greg C.; Wu, Ziji; Gierga, David; Buettner, Florian; Paganetti, Harald

    2008-01-01

    The purpose of this study was to investigate if interfraction and intrafraction motion in free-breathing and gated lung IMRT can lead to systematic dose differences between 3DCT and 4DCT. Dosimetric effects were studied considering the breathing pattern of three patients monitored during the course of their treatment and an in-house developed 4D Monte Carlo framework. Imaging data were taken in free-breathing and in cine mode for both 3D and 4D acquisition. Treatment planning for IMRT delivery was done based on the free-breathing data with the corvus (North American Scientific, Chatsworth, CA) planning system. The dose distributions as a function of phase in the breathing cycle were combined using deformable image registration. The study focused on (a) assessing the accuracy of the corvus pencil beam algorithm with Monte Carlo dose calculation in the lung, (b) evaluating the dosimetric effect of motion on the individual breathing phases of the respiratory cycle, and (c) assessing intrafraction and interfraction motion effects during free-breathing or gated radiotherapy. The comparison between (a) the planning system and the Monte Carlo system shows that the pencil beam algorithm underestimates the dose in low-density regions, such as lung tissue, and overestimates the dose in high-density regions, such as bone, by 5% or more of the prescribed dose (corresponding to approximately 3–5 Gy for the cases considered). For the patients studied this could have a significant impact on the dose volume histograms for the target structures depending on the margin added to the clinical target volume (CTV) to produce either the planning target (PTV) or internal target volume (ITV). The dose differences between (b) phases in the breathing cycle and the free-breathing case were shown to be negligible for all phases except for the inhale phase, where an underdosage of the tumor by as much as 9.3 Gy relative to the free-breathing was observed. The large difference was due to

  14. Development of a model of the coronary arterial tree for the 4D XCAT phantom

    NASA Astrophysics Data System (ADS)

    Fung, George S. K.; Segars, W. Paul; Gullberg, Grant T.; Tsui, Benjamin M. W.

    2011-09-01

    A detailed three-dimensional (3D) model of the coronary artery tree with cardiac motion has great potential for applications in a wide variety of medical imaging research areas. In this work, we first developed a computer-generated 3D model of the coronary arterial tree for the heart in the extended cardiac-torso (XCAT) phantom, thereby creating a realistic computer model of the human anatomy. The coronary arterial tree model was based on two datasets: (1) a gated cardiac dual-source computed tomography (CT) angiographic dataset obtained from a normal human subject and (2) statistical morphometric data of porcine hearts. The initial proximal segments of the vasculature and the anatomical details of the boundaries of the ventricles were defined by segmenting the CT data. An iterative rule-based generation method was developed and applied to extend the coronary arterial tree beyond the initial proximal segments. The algorithm was governed by three factors: (1) statistical morphometric measurements of the connectivity, lengths and diameters of the arterial segments; (2) avoidance forces from other vessel segments and the boundaries of the myocardium, and (3) optimality principles which minimize the drag force at the bifurcations of the generated tree. Using this algorithm, the 3D computational model of the largest six orders of the coronary arterial tree was generated, which spread across the myocardium of the left and right ventricles. The 3D coronary arterial tree model was then extended to 4D to simulate different cardiac phases by deforming the original 3D model according to the motion vector map of the 4D cardiac model of the XCAT phantom at the corresponding phases. As a result, a detailed and realistic 4D model of the coronary arterial tree was developed for the XCAT phantom by imposing constraints of anatomical and physiological characteristics of the coronary vasculature. This new 4D coronary artery tree model provides a unique simulation tool that can be

  15. Renal applications of dual-energy CT.

    PubMed

    Kaza, Ravi K; Platt, Joel F

    2016-06-01

    Dual-energy CT is being increasingly used for abdominal imaging due to its incremental benefit of material characterization without significant increase in radiation dose. Knowledge of the different dual-energy CT acquisition techniques and image processing algorithms is essential to optimize imaging protocols and understand potential limitations while using dual-energy CT renal imaging such as urinary calculi characterization, assessment of renal masses and in CT urography. This review article provides an overview of the current dual-energy CT techniques and use of dual-energy CT in renal imaging. PMID:27010938

  16. 2,4-Dichlorophenoxyacetic acid (2,4-D)

    Integrated Risk Information System (IRIS)

    2,4 - Dichlorophenoxyacetic acid ( 2,4 - D ) ; CASRN 94 - 75 - 7 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Asses

  17. CT -- Body

    MedlinePlus

    ... News Physician Resources Professions Site Index A-Z Computed Tomography (CT) - Body Computed tomography (CT) of the body uses special x-ray ... Body? What is CT Scanning of the Body? Computed tomography, more commonly known as a CT or CAT ...

  18. Super-resolution reconstruction for 4D computed tomography of the lung via the projections onto convex sets approach

    SciTech Connect

    Zhang, Yu E-mail: qianjinfeng08@gmail.com; Wu, Xiuxiu; Yang, Wei; Feng, Qianjin E-mail: qianjinfeng08@gmail.com; Chen, Wufan

    2014-11-01

    Purpose: The use of 4D computed tomography (4D-CT) of the lung is important in lung cancer radiotherapy for tumor localization and treatment planning. Sometimes, dense sampling is not acquired along the superior–inferior direction. This disadvantage results in an interslice thickness that is much greater than in-plane voxel resolutions. Isotropic resolution is necessary for multiplanar display, but the commonly used interpolation operation blurs images. This paper presents a super-resolution (SR) reconstruction method to enhance 4D-CT resolution. Methods: The authors assume that the low-resolution images of different phases at the same position can be regarded as input “frames” to reconstruct high-resolution images. The SR technique is used to recover high-resolution images. Specifically, the Demons deformable registration algorithm is used to estimate the motion field between different “frames.” Then, the projection onto convex sets approach is implemented to reconstruct high-resolution lung images. Results: The performance of the SR algorithm is evaluated using both simulated and real datasets. Their method can generate clearer lung images and enhance image structure compared with cubic spline interpolation and back projection (BP) method. Quantitative analysis shows that the proposed algorithm decreases the root mean square error by 40.8% relative to cubic spline interpolation and 10.2% versus BP. Conclusions: A new algorithm has been developed to improve the resolution of 4D-CT. The algorithm outperforms the cubic spline interpolation and BP approaches by producing images with markedly improved structural clarity and greatly reduced artifacts.

  19. 4D MR imaging using robust internal respiratory signal

    NASA Astrophysics Data System (ADS)

    Hui, CheukKai; Wen, Zhifei; Stemkens, Bjorn; Tijssen, R. H. N.; van den Berg, C. A. T.; Hwang, Ken-Pin; Beddar, Sam

    2016-05-01

    The purpose of this study is to investigate the feasibility of using internal respiratory (IR) surrogates to sort four-dimensional (4D) magnetic resonance (MR) images. The 4D MR images were constructed by acquiring fast 2D cine MR images sequentially, with each slice scanned for more than one breathing cycle. The 4D volume was then sorted retrospectively using the IR signal. In this study, we propose to use multiple low-frequency components in the Fourier space as well as the anterior body boundary as potential IR surrogates. From these potential IR surrogates, we used a clustering algorithm to identify those that best represented the respiratory pattern to derive the IR signal. A study with healthy volunteers was performed to assess the feasibility of the proposed IR signal. We compared this proposed IR signal with the respiratory signal obtained using respiratory bellows. Overall, 99% of the IR signals matched the bellows signals. The average difference between the end inspiration times in the IR signal and bellows signal was 0.18 s in this cohort of matching signals. For the acquired images corresponding to the other 1% of non-matching signal pairs, the respiratory motion shown in the images was coherent with the respiratory phases determined by the IR signal, but not the bellows signal. This suggested that the IR signal determined by the proposed method could potentially correct the faulty bellows signal. The sorted 4D images showed minimal mismatched artefacts and potential clinical applicability. The proposed IR signal therefore provides a feasible alternative to effectively sort MR images in 4D.

  20. 4D rotational x-ray imaging of wrist joint dynamic motion

    SciTech Connect

    Carelsen, Bart; Bakker, Niels H.; Strackee, Simon D.; Boon, Sjirk N.; Maas, Mario; Sabczynski, Joerg; Grimbergen, Cornelis A.; Streekstra, Geert J.

    2005-09-15

    Current methods for imaging joint motion are limited to either two-dimensional (2D) video fluoroscopy, or to animated motions from a series of static three-dimensional (3D) images. 3D movement patterns can be detected from biplane fluoroscopy images matched with computed tomography images. This involves several x-ray modalities and sophisticated 2D to 3D matching for the complex wrist joint. We present a method for the acquisition of dynamic 3D images of a moving joint. In our method a 3D-rotational x-ray (3D-RX) system is used to image a cyclically moving joint. The cyclic motion is synchronized to the x-ray acquisition to yield multiple sets of projection images, which are reconstructed to a series of time resolved 3D images, i.e., four-dimensional rotational x ray (4D-RX). To investigate the obtained image quality parameters the full width at half maximum (FWHM) of the point spread function (PSF) via the edge spread function and the contrast to noise ratio between air and phantom were determined on reconstructions of a bullet and rod phantom, using 4D-RX as well as stationary 3D-RX images. The CNR in volume reconstructions based on 251 projection images in the static situation and on 41 and 34 projection images of a moving phantom were 6.9, 3.0, and 2.9, respectively. The average FWHM of the PSF of these same images was, respectively, 1.1, 1.7, and 2.2 mm orthogonal to the motion and parallel to direction of motion 0.6, 0.7, and 1.0 mm. The main deterioration of 4D-RX images compared to 3D-RX images is due to the low number of projection images used and not to the motion of the object. Using 41 projection images seems the best setting for the current system. Experiments on a postmortem wrist show the feasibility of the method for imaging 3D dynamic joint motion. We expect that 4D-RX will pave the way to improved assessment of joint disorders by detection of 3D dynamic motion patterns in joints.

  1. Learning distance function for regression-based 4D pulmonary trunk model reconstruction estimated from sparse MRI data

    NASA Astrophysics Data System (ADS)

    Vitanovski, Dime; Tsymbal, Alexey; Ionasec, Razvan; Georgescu, Bogdan; Zhou, Shaohua K.; Hornegger, Joachim; Comaniciu, Dorin

    2011-03-01

    Congenital heart defect (CHD) is the most common birth defect and a frequent cause of death for children. Tetralogy of Fallot (ToF) is the most often occurring CHD which affects in particular the pulmonary valve and trunk. Emerging interventional methods enable percutaneous pulmonary valve implantation, which constitute an alternative to open heart surgery. While minimal invasive methods become common practice, imaging and non-invasive assessment tools become crucial components in the clinical setting. Cardiac computed tomography (CT) and cardiac magnetic resonance imaging (cMRI) are techniques with complementary properties and ability to acquire multiple non-invasive and accurate scans required for advance evaluation and therapy planning. In contrary to CT which covers the full 4D information over the cardiac cycle, cMRI often acquires partial information, for example only one 3D scan of the whole heart in the end-diastolic phase and two 2D planes (long and short axes) over the whole cardiac cycle. The data acquired in this way is called sparse cMRI. In this paper, we propose a regression-based approach for the reconstruction of the full 4D pulmonary trunk model from sparse MRI. The reconstruction approach is based on learning a distance function between the sparse MRI which needs to be completed and the 4D CT data with the full information used as the training set. The distance is based on the intrinsic Random Forest similarity which is learnt for the corresponding regression problem of predicting coordinates of unseen mesh points. Extensive experiments performed on 80 cardiac CT and MR sequences demonstrated the average speed of 10 seconds and accuracy of 0.1053mm mean absolute error for the proposed approach. Using the case retrieval workflow and local nearest neighbour regression with the learnt distance function appears to be competitive with respect to "black box" regression with immediate prediction of coordinates, while providing transparency to the

  2. Ansys Fluent versus Sim Vascular for 4-D patient-specific computational hemodynamics in renal arteries

    NASA Astrophysics Data System (ADS)

    Mumbaraddi, Avinash; Yu, Huidan (Whitney); Sawchuk, Alan; Dalsing, Michael

    2015-11-01

    The objective of this clinical-need driven research is to investigate the effect of renal artery stenosis (RAS) on the blood flow and wall shear stress in renal arteries through 4-D patient-specific computational hemodynamics (PSCH) and search for possible critical RASs that significantly alter the pressure gradient across the stenosis by manually varying the size of RAS from 50% to 95%. The identification of the critical RAS is important to understand the contribution of RAS to the overall renal resistance thus appropriate clinical therapy can be determined in order to reduce the hypertension. Clinical CT angiographic data together with Doppler Ultra sound images of an anonymous patient are used serving as the required inputs of the PSCH. To validate the PSCH, we use both Ansys Fluent and Sim Vascular and compare velocity, pressure, and wall-shear stress under identical conditions. Renal Imaging Technology Development Program (RITDP) Grant.

  3. Impact of scanning parameters and breathing patterns on image quality and accuracy of tumor motion reconstruction in 4D CBCT: a phantom study.

    PubMed

    Lee, Soyoung; Yan, Guanghua; Lu, Bo; Kahler, Darren; Li, Jonathan G; Sanjiv, Samat S

    2015-01-01

    Four-dimensional, cone-beam CT (4D CBCT) substantially reduces respiration-induced motion blurring artifacts in three-dimension (3D) CBCT. However, the image quality of 4D CBCT is significantly degraded which may affect its accuracy in localizing a mobile tumor for high-precision, image-guided radiation therapy (IGRT). The purpose of this study was to investigate the impact of scanning parameters hereinafter collectively referred to as scanning sequence) and breathing patterns on the image quality and the accuracy of computed tumor trajectory for a commercial 4D CBCT system, in preparation for its clinical implementation. We simulated a series of periodic and aperiodic sinusoidal breathing patterns with a respiratory motion phantom. The aperiodic pattern was created by varying the period or amplitude of individual sinusoidal breathing cycles. 4D CBCT scans of the phantom were acquired with a manufacturer-supplied scanning sequence (4D-S-slow) and two in-house modified scanning sequences (4D-M-slow and 4D-M-fast). While 4D-S-slow used small field of view (FOV), partial rotation (200°), and no imaging filter, 4D-M-slow and 4D-M-fast used medium FOV, full rotation, and the F1 filter. The scanning speed was doubled in 4D-M-fast (100°/min gantry rotation). The image quality of the 4D CBCT scans was evaluated using contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), and motion blurring ratio (MBR). The trajectory of the moving target was reconstructed by registering each phase of the 4D CBCT with a reference CT. The root-mean-squared-error (RMSE) analysis was used to quantify its accuracy. Significant decrease in CNR and SNR from 3D CBCT to 4D CBCT was observed. The 4D-S-slow and 4D-M-fast scans had comparable image quality, while the 4D-M-slow scans had better performance due to doubled projections. Both CNR and SNR decreased slightly as the breathing period increased, while no dependence on the amplitude was observed. The difference of both CNR and SNR

  4. Intelligent Vehicle Systems: A 4D/RCS Approach

    SciTech Connect

    Madhavan, Raj

    2007-04-01

    This book presents new research on autonomous mobility capabilities and shows how technological advances can be anticipated in the coming two decades. An in-depth description is presented on the theoretical foundations and engineering approaches that enable these capabilities. Chapter 1 provides a brief introduction to the 4D/RCS reference model architecture and design methodology that has proven successful in guiding the development of autonomous mobility systems. Chapters 2 through 7 provide more detailed descriptions of research that has been conducted and algorithms that have been developed to implement the various aspects of the 4D/RCS reference model architecture and design methodology. Chapters 8 and 9 discuss applications, performance measures, and standards. Chapter 10 provides a history of Army and DARPA research in autonomous ground mobility. Chapter 11 provides a perspective on the potential future developments in autonomous mobility.

  5. Exome sequencing identifies PDE4D mutations in acrodysostosis.

    PubMed

    Lee, Hane; Graham, John M; Rimoin, David L; Lachman, Ralph S; Krejci, Pavel; Tompson, Stuart W; Nelson, Stanley F; Krakow, Deborah; Cohn, Daniel H

    2012-04-01

    Acrodysostosis is a dominantly-inherited, multisystem disorder characterized by skeletal, endocrine, and neurological abnormalities. To identify the molecular basis of acrodysostosis, we performed exome sequencing on five genetically independent cases. Three different missense mutations in PDE4D, which encodes cyclic AMP (cAMP)-specific phosphodiesterase 4D, were found to be heterozygous in three of the cases. Two of the mutations were demonstrated to have occurred de novo, providing strong genetic evidence of causation. Two additional cases were heterozygous for de novo missense mutations in PRKAR1A, which encodes the cAMP-dependent regulatory subunit of protein kinase A and which has been recently reported to be the cause of a form of acrodysostosis resistant to multiple hormones. These findings demonstrate that acrodysostosis is genetically heterogeneous and underscore the exquisite sensitivity of many tissues to alterations in cAMP homeostasis. PMID:22464252

  6. 4D, Script N = 1 supersymmetry genomics (I)

    NASA Astrophysics Data System (ADS)

    Gates, S. James, Jr.; Gonzales, James; MacGregor, Boanne; Parker, James; Polo-Sherk, Ruben; Rodgers, Vincent G. J.; Wassink, Luke

    2009-12-01

    Presented in this paper the nature of the supersymmetrical representation theory behind 4D, Script N = 1 theories, as described by component fields, is investigated using the tools of Adinkras and Garden Algebras. A survey of familiar matter multiplets using these techniques reveals they are described by two fundamental valise Adinkras that are given the names of the cis-Valise (c-V) and the trans-Valise (t-V). A conjecture is made that all off-shell 4D, Script N = 1 component descriptions of supermultiplets are associated with two integers (nc, nt) — the numbers of c-V and t-V Adinkras that occur in the representation.

  7. Phosphodiesterase 4D gene polymorphisms in sudden sensorineural hearing loss.

    PubMed

    Chien, Chen-Yu; Tai, Shu-Yu; Wang, Ling-Feng; Hsi, Edward; Chang, Ning-Chia; Wang, Hsun-Mo; Wu, Ming-Tsang; Ho, Kuen-Yao

    2016-09-01

    The phosphodiesterase 4D (PDE4D) gene has been reported as a risk gene for ischemic stroke. The vascular factors are between the hypothesized etiologies of sudden sensorineural hearing loss (SSNHL), and this genetic effect might be attributed for its role in SSNHL. We hypothesized that genetic variants of the PDE4D gene are associated with susceptibility to SSNHL. We conducted a case-control study with 362 SSNHL cases and 209 controls. Three single nucleotide polymorphisms (SNPs) were selected. The genotypes were determined using TaqMan technology. Hardy-Weinberg equilibrium (HWE) was tested for each SNP, and genetic effects were evaluated according to three inheritance modes. We carried out sex-specific analysis to analyze the overall data. All three SNPs were in HWE. When subjects were stratified by sex, the genetic effect was only evident in females but not in males. The TT genotype of rs702553 exhibited an adjusted odds ratio (OR) of 3.83 (95 % confidence interval = 1.46-11.18) (p = 0.006) in female SSNHL. The TT genotype of SNP rs702553 was associated with female SSNHL under the recessive model (p = 0.004, OR 3.70). In multivariate logistic regression analysis, TT genotype of rs702553 was significantly associated with female SSNHL (p = 0.0043, OR 3.70). These results suggest that PDE4D gene polymorphisms influence the susceptibility for the development of SSNHL in the southern Taiwanese female population. PMID:26521189

  8. 4D remote sensing image coding with JPEG2000

    NASA Astrophysics Data System (ADS)

    Muñoz-Gómez, Juan; Bartrina-Rapesta, Joan; Blanes, Ian; Jiménez-Rodríguez, Leandro; Aulí-Llinàs, Francesc; Serra-Sagristà, Joan

    2010-08-01

    Multicomponent data have become popular in several scientific fields such as forest monitoring, environmental studies, or sea water temperature detection. Nowadays, this multicomponent data can be collected more than one time per year for the same region. This generates different instances in time of multicomponent data, also called 4D-Data (1D Temporal + 1D Spectral + 2D Spatial). For multicomponent data, it is important to take into account inter-band redundancy to produce a more compact representation of the image by packing the energy into fewer number of bands, thus enabling a higher compression performance. The principal decorrelators used to compact the inter-band correlation redundancy are the Karhunen Loeve Transform (KLT) and Discrete Wavelet Transform (DWT). Because of the Temporal Dimension added, the inter-band redundancy among different multicomponent images is increased. In this paper we analyze the influence of the Temporal Dimension (TD) and the Spectral Dimension (SD) in 4D-Data in terms of coding performance for JPEG2000, because it has support to apply different decorrelation stages and transforms to the components through the different dimensions. We evaluate the influence to perform different decorrelators techniques to the different dimensions. Also we will assess the performance of the two main decorrelation techniques, KLT and DWT. Experimental results are provided, showing rate-distortion performances encoding 4D-Data using KLT and WT techniques to the different dimensions TD and SD.

  9. 3D and 4D Seismic Imaging in the Oilfield; the state of the art

    NASA Astrophysics Data System (ADS)

    Strudley, A.

    2005-05-01

    has been driven by the need for improved recovery on declining fields, and for newer fields the requirement for optimised production. The vast majority of 4D activity is currently offshore based on the economic imperative in those environments. Much effort is being employed in the acquisition and processing domains to improve the resolution of the method, and to move from a qualitative to quantitative assessment of reservoir changes. Key developments in this field have been the improvements in data quality attained by new acquisition systems, growing maturity in processing of repeat datasets and the integration of seismic information into the reservoir management workflow. For the future there is much interest in the emplacement of semi-permanent seismic arrays to monitor reservoir changes on a very frequent basis (months rather than years). These arrays would also enable passive monitoring of reservoir changes between repeat seismic surveys. Despite the maturity and success of the 3D seismic method in the oilfield there are remaining challenges. Improvements to imaging schemes are required to address the need for ever more accurate subsurface images and the desire for improved reservoir performance is driving 4D technology forward. For the future we can expect even greater data densities than are currently acquired and developments in imaging based around increased computational resources.

  10. 4D scanning transmission ultrafast electron microscopy: Single-particle imaging and spectroscopy.

    PubMed

    Ortalan, Volkan; Zewail, Ahmed H

    2011-07-20

    We report the development of 4D scanning transmission ultrafast electron microscopy (ST-UEM). The method was demonstrated in the imaging of silver nanowires and gold nanoparticles. For the wire, the mechanical motion and shape morphological dynamics were imaged, and from the images we obtained the resonance frequency and the dephasing time of the motion. Moreover, we demonstrate here the simultaneous acquisition of dark-field images and electron energy loss spectra from a single gold nanoparticle, which is not possible with conventional methods. The local probing capabilities of ST-UEM open new avenues for probing dynamic processes, from single isolated to embedded nanostructures, without being affected by the heterogeneous processes of ensemble-averaged dynamics. Such methodology promises to have wide-ranging applications in materials science and in single-particle biological imaging. PMID:21615171

  11. New approach based on tetrahedral-mesh geometry for accurate 4D Monte Carlo patient-dose calculation.

    PubMed

    Han, Min Cheol; Yeom, Yeon Soo; Kim, Chan Hyeong; Kim, Seonghoon; Sohn, Jason W

    2015-02-21

    In the present study, to achieve accurate 4D Monte Carlo dose calculation in radiation therapy, we devised a new approach that combines (1) modeling of the patient body using tetrahedral-mesh geometry based on the patient's 4D CT data, (2) continuous movement/deformation of the tetrahedral patient model by interpolation of deformation vector fields acquired through deformable image registration, and (3) direct transportation of radiation particles during the movement and deformation of the tetrahedral patient model. The results of our feasibility study show that it is certainly possible to construct 4D patient models (= phantoms) with sufficient accuracy using the tetrahedral-mesh geometry and to directly transport radiation particles during continuous movement and deformation of the tetrahedral patient model. This new approach not only produces more accurate dose distribution in the patient but also replaces the current practice of using multiple 3D voxel phantoms and combining multiple dose distributions after Monte Carlo simulations. For routine clinical application of our new approach, the use of fast automatic segmentation algorithms is a must. In order to achieve, simultaneously, both dose accuracy and computation speed, the number of tetrahedrons for the lungs should be optimized. Although the current computation speed of our new 4D Monte Carlo simulation approach is slow (i.e. ~40 times slower than that of the conventional dose accumulation approach), this problem is resolvable by developing, in Geant4, a dedicated navigation class optimized for particle transportation in tetrahedral-mesh geometry. PMID:25615567

  12. 4-D reconstruction of fluorescence molecular tomography using re-assembled measurement data

    PubMed Central

    Liu, Xin; He, Xiaowe; Yan, Zhuangzhi; Lu, Hongbing

    2015-01-01

    Challenges remain in the reconstruction of dynamic (4-D) fluorescence molecular tomography (FMT). In our previous work, we implemented a fully 4-D FMT reconstruction approach using Karhunen-Loève (KL) transformation. However, in the reconstruction processes, the input data were scan-by-scan fluorescence projections. As a result, the reconstruction interval is limited by the data acquisition time for scanning one circle projections, leading to a long time (typically >1 min). In this paper, we propose a new method to reduce the reconstruction interval of dynamic FMT imaging, which is achieved by re-assembling the acquired fluorescence projection sequence. Further, to eliminate the temporal correlations within measurement data, the re-assembled projection sequence is reconstructed by the KL-based method. The numerical simulation and in vivo experiments are performed to evaluate the performance of the method. The experimental results indicate that after re-assembling measurement data, the reconstruction interval can be greatly reduced (~2.5 sec/frame). In addition, the proposed re-assembling method is helpful for improving reconstruction quality of the KL-based method. PMID:26114022

  13. Segmentation of 4D cardiac computer tomography images using active shape models

    NASA Astrophysics Data System (ADS)

    Leiner, Barba-J.; Olveres, Jimena; Escalante-Ramírez, Boris; Arámbula, Fernando; Vallejo, Enrique

    2012-06-01

    This paper describes a segmentation method for time series of 3D cardiac images based on deformable models. The goal of this work is to extend active shape models (ASM) of tree-dimensional objects to the problem of 4D (3D + time) cardiac CT image modeling. The segmentation is achieved by constructing a point distribution model (PDM) that encodes the spatio-temporal variability of a training set, i.e., the principal modes of variation of the temporal shapes are computed using some statistical parameters. An active search is used in the segmentation process where an initial approximation of the spatio-temporal shape is given and the gray level information in the neighborhood of the landmarks is analyzed. The starting shape is able to deform so as to better fit the data, but in the range allowed by the point distribution model. Several time series consisting of eleven 3D images of cardiac CT are employed for the method validation. Results are compared with manual segmentation made by an expert. The proposed application can be used for clinical evaluation of the left ventricle mechanical function. Likewise, the results can be taken as the first step of processing for optic flow estimation algorithms.

  14. 2,4-D impact on bacterial communities, and the activity and genetic potential of 2,4-D degrading communities in soil.

    PubMed

    Gonod, Laure Vieublé; Martin-Laurent, Fabrice; Chenu, Claire

    2006-12-01

    The key role of telluric microorganisms in pesticide degradation is well recognized but the possible relationships between the biodiversity of soil microbial communities and their functions still remain poorly documented. If microorganisms influence the fate of pesticides, pesticide application may reciprocally affect soil microorganisms. The objective of our work was to estimate the impact of 2,4-D application on the genetic structure of bacterial communities and the 2,4-D-degrading genetic potential in relation to 2,4-D mineralization. Experiments combined isotope measurements with molecular analyses. The impact of 2,4-D on soil bacterial populations was followed with ribosomal intergenic spacer analysis. The 2,4-D degrading genetic potential was estimated by real-time PCR targeted on tfdA sequences coding an enzyme specifically involved in 2,4-D mineralization. The genetic structure of bacterial communities was significantly modified in response to 2,4-D application, but only during the intense phase of 2,4-D biodegradation. This effect disappeared 7 days after the treatment. The 2,4-D degrading genetic potential increased rapidly following 2,4-D application. There was a concomitant increase between the tfdA copy number and the 14C microbial biomass. The maximum of tfdA sequences corresponded to the maximum rate of 2,4-D mineralization. In this soil, 2,4-D degrading microbial communities seem preferentially to use the tfd pathway to degrade 2,4-D. PMID:17117994

  15. Seeing the unseen--bioturbation in 4D: tracing bioirrigation in marine sediment using positron emission tomography and computed tomography.

    PubMed

    Delefosse, Matthieu; Kristensen, Erik; Crunelle, Diane; Braad, Poul Erik; Dam, Johan Hygum; Thisgaard, Helge; Thomassen, Anders; Høilund-Carlsen, Poul Flemming

    2015-01-01

    Understanding spatial and temporal patterns of bioirrigation induced by benthic fauna ventilation is critical given its significance on benthic nutrient exchange and biogeochemistry in coastal ecosystems. The quantification of this process challenges marine scientists because faunal activities and behaviors are concealed in an opaque sediment matrix. Here, we use a hybrid medical imaging technique, positron emission tomography and computed tomography (PET/CT) to provide a qualitative visual and fully quantitative description of bioirrigation in 4D (space and time). As a study case, we present images of porewater advection induced by the well-studied lugworm (Arenicola marina). Our results show that PET/CT allows more comprehensive studies on ventilation and bioirrigation than possible using techniques traditionally applied in marine ecology. We provide a dynamic three-dimensional description of bioirrigation by the lugworm at very high temporal and spatial resolution. Results obtained with the PET/CT are in agreement with literature data on lugworm ventilation and bioirrigation. Major advantages of PET/CT over methods commonly used are its non-invasive and non-destructive approach and its capacity to provide information that otherwise would require multiple methods. Furthermore, PET/CT scan is versatile as it can be used for a variety of benthic macrofauna species and sediment types and it provides information on burrow morphology or animal behavior. The lack of accessibility to the expensive equipment is its major drawback which can only be overcome through collaboration among several institutions. PMID:25837626

  16. Seeing the Unseen—Bioturbation in 4D: Tracing Bioirrigation in Marine Sediment Using Positron Emission Tomography and Computed Tomography

    PubMed Central

    Delefosse, Matthieu; Kristensen, Erik; Crunelle, Diane; Braad, Poul Erik; Dam, Johan Hygum; Thisgaard, Helge; Thomassen, Anders; Høilund-Carlsen, Poul Flemming

    2015-01-01

    Understanding spatial and temporal patterns of bioirrigation induced by benthic fauna ventilation is critical given its significance on benthic nutrient exchange and biogeochemistry in coastal ecosystems. The quantification of this process challenges marine scientists because faunal activities and behaviors are concealed in an opaque sediment matrix. Here, we use a hybrid medical imaging technique, positron emission tomography and computed tomography (PET/CT) to provide a qualitative visual and fully quantitative description of bioirrigation in 4D (space and time). As a study case, we present images of porewater advection induced by the well-studied lugworm (Arenicola marina). Our results show that PET/CT allows more comprehensive studies on ventilation and bioirrigation than possible using techniques traditionally applied in marine ecology. We provide a dynamic three-dimensional description of bioirrigation by the lugworm at very high temporal and spatial resolution. Results obtained with the PET/CT are in agreement with literature data on lugworm ventilation and bioirrigation. Major advantages of PET/CT over methods commonly used are its non-invasive and non-destructive approach and its capacity to provide information that otherwise would require multiple methods. Furthermore, PET/CT scan is versatile as it can be used for a variety of benthic macrofauna species and sediment types and it provides information on burrow morphology or animal behavior. The lack of accessibility to the expensive equipment is its major drawback which can only be overcome through collaboration among several institutions. PMID:25837626

  17. CT Scans

    MedlinePlus

    ... cross-sectional pictures of your body. Doctors use CT scans to look for Broken bones Cancers Blood clots Signs of heart disease Internal bleeding During a CT scan, you lie still on a table. The table ...

  18. 18F-FDG PET/CT oncologic imaging at extended injection-to-scan acquisition time intervals derived from a single-institution 18F-FDG-directed surgery experience: feasibility and quantification of 18F-FDG accumulation within 18F-FDG-avid lesions and background tissues

    PubMed Central

    2014-01-01

    Background 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) is a well-established imaging modality for a wide variety of solid malignancies. Currently, only limited data exists regarding the utility of PET/CT imaging at very extended injection-to-scan acquisition times. The current retrospective data analysis assessed the feasibility and quantification of diagnostic 18F-FDG PET/CT oncologic imaging at extended injection-to-scan acquisition time intervals. Methods 18F-FDG-avid lesions (not surgically manipulated or altered during 18F-FDG-directed surgery, and visualized both on preoperative and postoperative 18F-FDG PET/CT imaging) and corresponding background tissues were assessed for 18F-FDG accumulation on same-day preoperative and postoperative 18F-FDG PET/CT imaging. Multiple patient variables and 18F-FDG-avid lesion variables were examined. Results For the 32 18F-FDG-avid lesions making up the final 18F-FDG-avid lesion data set (from among 7 patients), the mean injection-to-scan times of the preoperative and postoperative 18F-FDG PET/CT scans were 73 (±3, 70-78) and 530 (±79, 413-739) minutes, respectively (P < 0.001). The preoperative and postoperative mean 18F-FDG-avid lesion SUVmax values were 7.7 (±4.0, 3.6-19.5) and 11.3 (±6.0, 4.1-29.2), respectively (P < 0.001). The preoperative and postoperative mean background SUVmax values were 2.3 (±0.6, 1.0-3.2) and 2.1 (±0.6, 1.0-3.3), respectively (P = 0.017). The preoperative and postoperative mean lesion-to-background SUVmax ratios were 3.7 (±2.3, 1.5-9.8) and 5.8 (±3.6, 1.6-16.2), respectively, (P < 0.001). Conclusions 18F-FDG PET/CT oncologic imaging can be successfully performed at extended injection-to-scan acquisition time intervals of up to approximately 5 half-lives for 18F-FDG while maintaining good/adequate diagnostic image quality. The resultant increase in the 18F-FDG-avid lesion SUVmax values, decreased background SUVmax values, and

  19. Automatic segmentation of phase-correlated CT scans through nonrigid image registration using geometrically regularized free-form deformation

    SciTech Connect

    Shekhar, Raj; Lei, Peng; Castro-Pareja, Carlos R.; Plishker, William L.; D'Souza, Warren D.

    2007-07-15

    Conventional radiotherapy is planned using free-breathing computed tomography (CT), ignoring the motion and deformation of the anatomy from respiration. New breath-hold-synchronized, gated, and four-dimensional (4D) CT acquisition strategies are enabling radiotherapy planning utilizing a set of CT scans belonging to different phases of the breathing cycle. Such 4D treatment planning relies on the availability of tumor and organ contours in all phases. The current practice of manual segmentation is impractical for 4D CT, because it is time consuming and tedious. A viable solution is registration-based segmentation, through which contours provided by an expert for a particular phase are propagated to all other phases while accounting for phase-to-phase motion and anatomical deformation. Deformable image registration is central to this task, and a free-form deformation-based nonrigid image registration algorithm will be presented. Compared with the original algorithm, this version uses novel, computationally simpler geometric constraints to preserve the topology of the dense control-point grid used to represent free-form deformation and prevent tissue fold-over. Using mean squared difference as an image similarity criterion, the inhale phase is registered to the exhale phase of lung CT scans of five patients and of characteristically low-contrast abdominal CT scans of four patients. In addition, using expert contours for the inhale phase, the corresponding contours were automatically generated for the exhale phase. The accuracy of the segmentation (and hence deformable image registration) was judged by comparing automatically segmented contours with expert contours traced directly in the exhale phase scan using three metrics: volume overlap index, root mean square distance, and Hausdorff distance. The accuracy of the segmentation (in terms of radial distance mismatch) was approximately 2 mm in the thorax and 3 mm in the abdomen, which compares favorably to the

  20. 4D numerical observer for lesion detection in respiratory-gated PET

    SciTech Connect

    Lorsakul, Auranuch; Li, Quanzheng; Ouyang, Jinsong; El Fakhri, Georges; Trott, Cathryn M.; Hoog, Christopher; Petibon, Yoann; Laine, Andrew F.

    2014-10-15

    Purpose: Respiratory-gated positron emission tomography (PET)/computed tomography protocols reduce lesion smearing and improve lesion detection through a synchronized acquisition of emission data. However, an objective assessment of image quality of the improvement gained from respiratory-gated PET is mainly limited to a three-dimensional (3D) approach. This work proposes a 4D numerical observer that incorporates both spatial and temporal informations for detection tasks in pulmonary oncology. Methods: The authors propose a 4D numerical observer constructed with a 3D channelized Hotelling observer for the spatial domain followed by a Hotelling observer for the temporal domain. Realistic {sup 18}F-fluorodeoxyglucose activity distributions were simulated using a 4D extended cardiac torso anthropomorphic phantom including 12 spherical lesions at different anatomical locations (lower, upper, anterior, and posterior) within the lungs. Simulated data based on Monte Carlo simulation were obtained using GEANT4 application for tomographic emission (GATE). Fifty noise realizations of six respiratory-gated PET frames were simulated by GATE using a model of the Siemens Biograph mMR scanner geometry. PET sinograms of the thorax background and pulmonary lesions that were simulated separately were merged to generate different conditions of the lesions to the background (e.g., lesion contrast and motion). A conventional ordered subset expectation maximization (OSEM) reconstruction (5 iterations and 6 subsets) was used to obtain: (1) gated, (2) nongated, and (3) motion-corrected image volumes (a total of 3200 subimage volumes: 2400 gated, 400 nongated, and 400 motion-corrected). Lesion-detection signal-to-noise ratios (SNRs) were measured in different lesion-to-background contrast levels (3.5, 8.0, 9.0, and 20.0), lesion diameters (10.0, 13.0, and 16.0 mm), and respiratory motion displacements (17.6–31.3 mm). The proposed 4D numerical observer applied on multiple-gated images was

  1. 4D numerical observer for lesion detection in respiratory-gated PET

    PubMed Central

    Lorsakul, Auranuch; Li, Quanzheng; Trott, Cathryn M.; Hoog, Christopher; Petibon, Yoann; Ouyang, Jinsong; Laine, Andrew F.; El Fakhri, Georges

    2014-01-01

    Purpose: Respiratory-gated positron emission tomography (PET)/computed tomography protocols reduce lesion smearing and improve lesion detection through a synchronized acquisition of emission data. However, an objective assessment of image quality of the improvement gained from respiratory-gated PET is mainly limited to a three-dimensional (3D) approach. This work proposes a 4D numerical observer that incorporates both spatial and temporal informations for detection tasks in pulmonary oncology. Methods: The authors propose a 4D numerical observer constructed with a 3D channelized Hotelling observer for the spatial domain followed by a Hotelling observer for the temporal domain. Realistic 18F-fluorodeoxyglucose activity distributions were simulated using a 4D extended cardiac torso anthropomorphic phantom including 12 spherical lesions at different anatomical locations (lower, upper, anterior, and posterior) within the lungs. Simulated data based on Monte Carlo simulation were obtained using geant4 application for tomographic emission (GATE). Fifty noise realizations of six respiratory-gated PET frames were simulated by GATE using a model of the Siemens Biograph mMR scanner geometry. PET sinograms of the thorax background and pulmonary lesions that were simulated separately were merged to generate different conditions of the lesions to the background (e.g., lesion contrast and motion). A conventional ordered subset expectation maximization (OSEM) reconstruction (5 iterations and 6 subsets) was used to obtain: (1) gated, (2) nongated, and (3) motion-corrected image volumes (a total of 3200 subimage volumes: 2400 gated, 400 nongated, and 400 motion-corrected). Lesion-detection signal-to-noise ratios (SNRs) were measured in different lesion-to-background contrast levels (3.5, 8.0, 9.0, and 20.0), lesion diameters (10.0, 13.0, and 16.0 mm), and respiratory motion displacements (17.6–31.3 mm). The proposed 4D numerical observer applied on multiple-gated images was

  2. Poster — Thur Eve — 71: A 4D Multimodal Lung Phantom for Regmentation Evaluation

    SciTech Connect

    Markel, D; Levesque, I R; El Naqa, I

    2014-08-15

    Segmentation and registration of medical imaging data are two processes that can be integrated (a process termed regmentation) to iteratively reinforce each other, potentially improving efficiency and overall accuracy. A significant challenge is presented when attempting to validate the joint process particularly with regards to minimizing geometric uncertainties associated with the ground truth while maintaining anatomical realism. This work demonstrates a 4D MRI, PET, and CT compatible tissue phantom with a known ground truth for evaluating registration and segmentation accuracy. The phantom consists of a preserved swine lung connected to an air pump via a PVC tube for inflation. Mock tumors were constructed from sea sponges contained within two vacuum-sealed compartments with catheters running into each one for injection of radiotracer solution. The phantom was scanned using a GE Discovery-ST PET/CT scanner and a 0.23T Phillips MRI, and resulted in anatomically realistic images. A bifurcation tracking algorithm was implemented to provide a ground truth for evaluating registration accuracy. This algorithm was validated using known deformations of up to 7.8 cm using a separate CT scan of a human thorax. Using the known deformation vectors to compare against, 76 bifurcation points were selected. The tracking accuracy was found to have maximum mean errors of −0.94, 0.79 and −0.57 voxels in the left-right, anterior-posterior and inferior-superior directions, respectively. A pneumatic control system is under development to match the respiratory profile of the lungs to a breathing trace from an individual patient.

  3. CT number variations in micro CT imaging systems

    NASA Astrophysics Data System (ADS)

    Tu, Shu-Ju; Hsieh, Hui-Ling; Chao, Tsi-Chian

    2008-03-01

    CT numbers can be directly computed from the linear attenuation coefficients in the reconstructed CT images and are correlated to the electron densities of the chemical elements with specific atomic numbers. However, the computed CT numbers can be varied when different imaging parameters are used. Phantoms composed of clinically relevant and tissue-equivalent materials (lung, bone, muscle, and adipose) were scanned with a commercial circular-scanning micro CT imager. This imaging system is composed with a micro-focused x-ray tube and charged-coupled device (CCD) camera as the detector. The mean CT numbers and the corresponding standard deviations in terms of Hounsfield units were then computed from a pre-defined region of interest located within the reconstructed volumetric images. The variations of CT number were then identified from a series of imaging parameters. Those parameters include imaging acquisition modes (e.g., the metal filter used in the x-ray tube), reconstruction methods (e.g., Feldkamp and iterative algorithm), and post-image processing techniques (e.g., ring artifact, beam-hardening artifact, and smoothing processing). These variations of CT numbers are useful and important in tissue characterization, quantitative bone structure analysis, bone marrow density evaluation, and Monte Carlo dose calculations for the pilot small animal study when micro CT imaging systems are employed. Also these variations can be used as the quantification for the performance of the micro CT imaging systems.

  4. Non-spherical particle generation from 4D optofluidic fabrication.

    PubMed

    Paulsen, Kevin S; Chung, Aram J

    2016-08-01

    Particles with non-spherical shapes can exhibit properties which are not available from spherical shaped particles. Complex shaped particles can provide unique benefits for areas such as drug delivery, tissue engineering, structural materials, and self-assembly building blocks. Current methods of creating complex shaped particles such as 3D printing, photolithography, and imprint lithography are limited by either slow speeds, shape limitations, or expensive processes. Previously, we presented a novel microfluidic flow lithography fabrication scheme combined with fluid inertia called optofluidic fabrication for the creation of complex shaped three-dimensional (3D) particles. This process was able to address the aforementioned limits and overcome two-dimensional shape limitations faced by traditional flow lithography methods; however, all of the created 3D particle shapes displayed top-down symmetry. Here, by introducing the time dimension into our existing optofluidic fabrication process, we break this top-down symmetry, generating fully asymmetric 3D particles where we termed the process: four-dimensional (4D) optofluidic fabrication. This 4D optofluidic fabrication is comprised of three sequential procedures. First, density mismatched precursor fluids flow past pillars within fluidic channels to manipulate the flow cross sections via fluid inertia. Next, the time dimension is incorporated by stopping the flow and allowing the denser fluids to settle by gravity to create asymmetric flow cross sections. Finally, the fluids are exposed to patterned ultraviolet (UV) light in order to polymerize fully asymmetric 3D-shaped particles. By varying inertial flow shaping, gravity-induced flow shaping, and UV light patterns, 4D optofluidic fabrication can create an infinite set of complex shaped asymmetric particles. PMID:27092661

  5. Localization of 4D gravity on pure geometrical thick branes

    SciTech Connect

    Barbosa-Cendejas, Nandinii; Herrera-Aguilar, Alfredo

    2006-04-15

    We consider the generation of thick brane configurations in a pure geometric Weyl integrable 5D spacetime which constitutes a non-Riemannian generalization of Kaluza-Klein (KK) theory. In this framework, we show how 4D gravity can be localized on a scalar thick brane which does not necessarily respect reflection symmetry, generalizing in this way several previous models based on the Randall-Sundrum (RS) system and avoiding both, the restriction to orbifold geometries and the introduction of the branes in the action by hand. We first obtain a thick brane solution that preserves 4D Poincare invariance and breaks Z{sub 2}-symmetry along the extra dimension which, indeed, can be either compact or extended, and supplements brane solutions previously found by other authors. In the noncompact case, this field configuration represents a thick brane with positive energy density centered at y=c{sub 2}, whereas pairs of thick branes arise in the compact case. Remarkably, the Weylian scalar curvature is nonsingular along the fifth dimension in the noncompact case, in contraposition to the RS thin brane system. We also recast the wave equations of the transverse traceless modes of the linear fluctuations of the classical background into a Schroedinger's equation form with a volcano potential of finite bottom in both the compact and the extended cases. We solve Schroedinger equation for the massless zero mode m{sup 2}=0 and obtain a single bound wave function which represents a stable 4D graviton. We also get a continuum gapless spectrum of KK states with m{sup 2}>0 that are suppressed at y=c{sub 2} and turn asymptotically into plane waves.

  6. Multicolor 4D Fluorescence Microscopy using Ultrathin Bessel Light Sheets

    PubMed Central

    Zhao, Teng; Lau, Sze Cheung; Wang, Ying; Su, Yumian; Wang, Hao; Cheng, Aifang; Herrup, Karl; Ip, Nancy Y.; Du, Shengwang; Loy, M. M. T.

    2016-01-01

    We demonstrate a simple and efficient method for producing ultrathin Bessel (‘non-diffracting’) light sheets of any color using a line-shaped beam and an annulus filter. With this robust and cost-effective technology, we obtained two-color, 3D images of biological samples with lateral/axial resolution of 250 nm/400 nm, and high-speed, 4D volume imaging of 20 μm sized live sample at 1 Hz temporal resolution. PMID:27189786

  7. Oblique sounding using the DPS-4D stations in Europe

    NASA Astrophysics Data System (ADS)

    Mosna, Zbysek; Kouba, Daniel; Koucka Knizova, Petra; Arikan, Feza; Arikan, Orhan; Gok, Gokhan; Rejfek, Lubos

    2016-07-01

    The DPS-4D Digisondes are capable of detection of echoes from neighbouring European stations. Currently, a campaign with high-temporal resolution of 5 min is being run. Further, ionograms from regular vertical sounding with 15 min resolution provide us with oblique reflections together with vertical reflections. We analyzed profiles of electron concentration and basic ionospheric parameters derived from the ionograms. We compared results derived from reflections from the ionosphere above the stations (vertical sounding) with information derived from oblique reflections between the stations. This study is supported by the Joint TUBITAK 114E092 and AS CR 14/001 projects.

  8. All the supersymmetric configurations of N=4, d=4 supergravity

    NASA Astrophysics Data System (ADS)

    Bellorín, Jorge; Ortín, Tomás

    2005-10-01

    All the supersymmetric configurations of pure, ungauged, N=4, d=4 supergravity are classified in a formalism that keeps manifest the S and T dualities of the theory. We also find simple equations that need to be satisfied by the configurations to be classical solutions of the theory. While the solutions associated to null Killing vectors were essentially classified by Tod (a classification that we refine), we find new configurations and solutions associated to timelike Killing vectors that do not satisfy Tod's rigidity hypothesis (hence, they have a nontrivial U(1) connection) and whose supersymmetry projector is associated to 1-dimensional objects (strings), although they have a trivial axion field.

  9. Multielectron Spectroscopy: The Xenon 4d Hole Double Auger Decay

    SciTech Connect

    Penent, F.; Palaudoux, J.; Lablanquie, P.; Andric, L.; Feifel, R.; Eland, J.H.D.

    2005-08-19

    A magnetic bottle spectrometer of the type recently developed by Eland et al. [Phys. Rev. Lett. 90, 053003 (2003).] has been implemented for use with synchrotron radiation, allowing multidimensional electron spectroscopy. Its application to the Xe 4d double Auger decay reveals all the energy pathways involved. The dominant path is a cascade process with a rapid (6 fs) ejection of a first Auger electron followed by the slower (>23 fs) emission of a second Auger electron. Weaker processes implying 3 electron processes are also revealed, namely, direct double Auger and associated Rydberg series.

  10. Founding Gravitation in 4D Euclidean Space-Time Geometry

    SciTech Connect

    Winkler, Franz-Guenter

    2010-11-24

    The Euclidean interpretation of special relativity which has been suggested by the author is a formulation of special relativity in ordinary 4D Euclidean space-time geometry. The natural and geometrically intuitive generalization of this view involves variations of the speed of light (depending on location and direction) and a Euclidean principle of general covariance. In this article, a gravitation model by Jan Broekaert, which implements a view of relativity theory in the spirit of Lorentz and Poincare, is reconstructed and shown to fulfill the principles of the Euclidean approach after an appropriate reinterpretation.

  11. Multicolor 4D Fluorescence Microscopy using Ultrathin Bessel Light Sheets.

    PubMed

    Zhao, Teng; Lau, Sze Cheung; Wang, Ying; Su, Yumian; Wang, Hao; Cheng, Aifang; Herrup, Karl; Ip, Nancy Y; Du, Shengwang; Loy, M M T

    2016-01-01

    We demonstrate a simple and efficient method for producing ultrathin Bessel ('non-diffracting') light sheets of any color using a line-shaped beam and an annulus filter. With this robust and cost-effective technology, we obtained two-color, 3D images of biological samples with lateral/axial resolution of 250 nm/400 nm, and high-speed, 4D volume imaging of 20 μm sized live sample at 1 Hz temporal resolution. PMID:27189786

  12. 4D tumor centroid tracking using orthogonal 2D dynamic MRI: Implications for radiotherapy planning

    SciTech Connect

    Tryggestad, Erik; Flammang, Aaron; Shea, Steven M.; Hales, Russell; Herman, Joseph; Lee, Junghoon; McNutt, Todd; Roland, Teboh; Wong, John

    2013-09-15

    Purpose: Current pretreatment, 4D imaging techniques are suboptimal in that they sample breathing motion over a very limited “snapshot” in time. Heretofore, long-duration, 4D motion characterization for radiotherapy planning, margin optimization, and validation have been impractical for safety reasons, requiring invasive markers imaged under x-ray fluoroscopy. To characterize 3D tumor motion and associated variability over durations more consistent with treatments, the authors have developed a practical dynamic MRI (dMRI) technique employing two orthogonal planes acquired in a continuous, interleaved fashion.Methods: 2D balanced steady-state free precession MRI was acquired continuously over 9–14 min at approximately 4 Hz in three healthy volunteers using a commercial 1.5 T system; alternating orthogonal imaging planes (sagittal, coronal, sagittal, etc.) were employed. The 2D in-plane pixel resolution was 2 × 2 mm{sup 2} with a 5 mm slice profile. Simultaneous with image acquisition, the authors monitored a 1D surrogate respiratory signal using a device available with the MRI system. 2D template matching-based anatomic feature registration, or tracking, was performed independently in each orientation. 4D feature tracking at the raw frame rate was derived using spline interpolation.Results: Tracking vascular features in the lung for two volunteers and pancreatic features in one volunteer, the authors have successfully demonstrated this method. Registration error, defined here as the difference between the sagittal and coronal tracking result in the SI direction, ranged from 0.7 to 1.6 mm (1σ) which was less than the acquired image resolution. Although the healthy volunteers were instructed to relax and breathe normally, significantly variable respiration was observed. To demonstrate potential applications of this technique, the authors subsequently explored the intrafraction stability of hypothetical tumoral internal target volumes and 3D spatial probability

  13. Evaluation of intrinsic respiratory signal determination methods for 4D CBCT adapted for mice

    SciTech Connect

    Martin, Rachael; Pan, Tinsu; Rubinstein, Ashley; Court, Laurence; Ahmad, Moiz

    2015-01-15

    Purpose: 4D CT imaging in mice is important in a variety of areas including studies of lung function and tumor motion. A necessary step in 4D imaging is obtaining a respiratory signal, which can be done through an external system or intrinsically through the projection images. A number of methods have been developed that can successfully determine the respiratory signal from cone-beam projection images of humans, however only a few have been utilized in a preclinical setting and most of these rely on step-and-shoot style imaging. The purpose of this work is to assess and make adaptions of several successful methods developed for humans for an image-guided preclinical radiation therapy system. Methods: Respiratory signals were determined from the projection images of free-breathing mice scanned on the X-RAD system using four methods: the so-called Amsterdam shroud method, a method based on the phase of the Fourier transform, a pixel intensity method, and a center of mass method. The Amsterdam shroud method was modified so the sharp inspiration peaks associated with anesthetized mouse breathing could be detected. Respiratory signals were used to sort projections into phase bins and 4D images were reconstructed. Error and standard deviation in the assignment of phase bins for the four methods compared to a manual method considered to be ground truth were calculated for a range of region of interest (ROI) sizes. Qualitative comparisons were additionally made between the 4D images obtained using each of the methods and the manual method. Results: 4D images were successfully created for all mice with each of the respiratory signal extraction methods. Only minimal qualitative differences were noted between each of the methods and the manual method. The average error (and standard deviation) in phase bin assignment was 0.24 ± 0.08 (0.49 ± 0.11) phase bins for the Fourier transform method, 0.09 ± 0.03 (0.31 ± 0.08) phase bins for the modified Amsterdam shroud method, 0

  14. Functional organization of the human 4D Nucleome

    PubMed Central

    Chen, Haiming; Chen, Jie; Muir, Lindsey A.; Ronquist, Scott; Meixner, Walter; Ljungman, Mats; Ried, Thomas; Smale, Stephen; Rajapakse, Indika

    2015-01-01

    The 4D organization of the interphase nucleus, or the 4D Nucleome (4DN), reflects a dynamical interaction between 3D genome structure and function and its relationship to phenotype. We present initial analyses of the human 4DN, capturing genome-wide structure using chromosome conformation capture and 3D imaging, and function using RNA-sequencing. We introduce a quantitative index that measures underlying topological stability of a genomic region. Our results show that structural features of genomic regions correlate with function with surprising persistence over time. Furthermore, constructing genome-wide gene-level contact maps aided in identifying gene pairs with high potential for coregulation and colocalization in a manner consistent with expression via transcription factories. We additionally use 2D phase planes to visualize patterns in 4DN data. Finally, we evaluated gene pairs within a circadian gene module using 3D imaging, and found periodicity in the movement of clock circadian regulator and period circadian clock 2 relative to each other that followed a circadian rhythm and entrained with their expression. PMID:26080430

  15. Perspective: 4D ultrafast electron microscopy--Evolutions and revolutions.

    PubMed

    Shorokhov, Dmitry; Zewail, Ahmed H

    2016-02-28

    In this Perspective, the evolutionary and revolutionary developments of ultrafast electron imaging are overviewed with focus on the "single-electron concept" for probing methodology. From the first electron microscope of Knoll and Ruska [Z. Phys. 78, 318 (1932)], constructed in the 1930s, to aberration-corrected instruments and on, to four-dimensional ultrafast electron microscopy (4D UEM), the developments over eight decades have transformed humans' scope of visualization. The changes in the length and time scales involved are unimaginable, beginning with the micrometer and second domains, and now reaching the space and time dimensions of atoms in matter. With these advances, it has become possible to follow the elementary structural dynamics as it unfolds in real time and to provide the means for visualizing materials behavior and biological functions. The aim is to understand emergent phenomena in complex systems, and 4D UEM is now central for the visualization of elementary processes involved, as illustrated here with examples from past achievements and future outlook. PMID:26931672

  16. 488-4D ASH LANDFILL CLOSURE CAP HELP MODELING

    SciTech Connect

    Phifer, M.

    2014-11-17

    At the request of Area Completion Projects (ACP) in support of the 488-4D Landfill closure, the Savannah River National Laboratory (SRNL) has performed Hydrologic Evaluation of Landfill Performance (HELP) modeling of the planned 488-4D Ash Landfill closure cap to ensure that the South Carolina Department of Health and Environmental Control (SCDHEC) limit of no more than 12 inches of head on top of the barrier layer (saturated hydraulic conductivity of no more than 1.0E-05 cm/s) in association with a 25-year, 24-hour storm event is not projected to be exceeded. Based upon Weber 1998 a 25-year, 24-hour storm event at the Savannah River Site (SRS) is 6.1 inches. The results of the HELP modeling indicate that the greatest peak daily head on top of the barrier layer (i.e. geosynthetic clay liner (GCL) or high density polyethylene (HDPE) geomembrane) for any of the runs made was 0.079 inches associated with a peak daily precipitation of 6.16 inches. This is well below the SCDHEC limit of 12 inches.

  17. Perspective: 4D ultrafast electron microscopy—Evolutions and revolutions

    NASA Astrophysics Data System (ADS)

    Shorokhov, Dmitry; Zewail, Ahmed H.

    2016-02-01

    In this Perspective, the evolutionary and revolutionary developments of ultrafast electron imaging are overviewed with focus on the "single-electron concept" for probing methodology. From the first electron microscope of Knoll and Ruska [Z. Phys. 78, 318 (1932)], constructed in the 1930s, to aberration-corrected instruments and on, to four-dimensional ultrafast electron microscopy (4D UEM), the developments over eight decades have transformed humans' scope of visualization. The changes in the length and time scales involved are unimaginable, beginning with the micrometer and second domains, and now reaching the space and time dimensions of atoms in matter. With these advances, it has become possible to follow the elementary structural dynamics as it unfolds in real time and to provide the means for visualizing materials behavior and biological functions. The aim is to understand emergent phenomena in complex systems, and 4D UEM is now central for the visualization of elementary processes involved, as illustrated here with examples from past achievements and future outlook.

  18. 4D Dynamic Required Navigation Performance Final Report

    NASA Technical Reports Server (NTRS)

    Finkelsztein, Daniel M.; Sturdy, James L.; Alaverdi, Omeed; Hochwarth, Joachim K.

    2011-01-01

    New advanced four dimensional trajectory (4DT) procedures under consideration for the Next Generation Air Transportation System (NextGen) require an aircraft to precisely navigate relative to a moving reference such as another aircraft. Examples are Self-Separation for enroute operations and Interval Management for in-trail and merging operations. The current construct of Required Navigation Performance (RNP), defined for fixed-reference-frame navigation, is not sufficiently specified to be applicable to defining performance levels of such air-to-air procedures. An extension of RNP to air-to-air navigation would enable these advanced procedures to be implemented with a specified level of performance. The objective of this research effort was to propose new 4D Dynamic RNP constructs that account for the dynamic spatial and temporal nature of Interval Management and Self-Separation, develop mathematical models of the Dynamic RNP constructs, "Required Self-Separation Performance" and "Required Interval Management Performance," and to analyze the performance characteristics of these air-to-air procedures using the newly developed models. This final report summarizes the activities led by Raytheon, in collaboration with GE Aviation and SAIC, and presents the results from this research effort to expand the RNP concept to a dynamic 4D frame of reference.

  19. Positive Energy Conditions in 4D Conformal Field Theory

    NASA Astrophysics Data System (ADS)

    Farnsworth, Kara; Luty, Markus; Prilepina, Valentina

    2016-03-01

    We argue that all consistent 4D quantum field theories obey a spacetime-averaged weak energy inequality avgT00 >= - C /L4 , where L is the size of the smearing region, and C is a positive constant that depends on the theory. If this condition is violated, the theory has states that are indistinguishable from states of negative total energy by any local measurement, and we expect instabilities or other inconsistencies. We apply this condition to 4D conformal field theories, and find that it places constraints on the OPE coefficients of the theory. The constraints we find are weaker than the ``conformal collider'' constraints of Hofman and Maldacena. We speculate that there may be theories that violate the Hofman-Maldacena bounds, but satisfy our bounds. In 3D CFTs, the only constraint we find is equivalent to the positivity of 2-point function of the energy-momentum tensor, which follows from unitarity. Our calculations are performed using momentum-space Wightman functions, which are remarkably simple functions of momenta, and may be of interest in their own right.

  20. Functional organization of the human 4D Nucleome.

    PubMed

    Chen, Haiming; Chen, Jie; Muir, Lindsey A; Ronquist, Scott; Meixner, Walter; Ljungman, Mats; Ried, Thomas; Smale, Stephen; Rajapakse, Indika

    2015-06-30

    The 4D organization of the interphase nucleus, or the 4D Nucleome (4DN), reflects a dynamical interaction between 3D genome structure and function and its relationship to phenotype. We present initial analyses of the human 4DN, capturing genome-wide structure using chromosome conformation capture and 3D imaging, and function using RNA-sequencing. We introduce a quantitative index that measures underlying topological stability of a genomic region. Our results show that structural features of genomic regions correlate with function with surprising persistence over time. Furthermore, constructing genome-wide gene-level contact maps aided in identifying gene pairs with high potential for coregulation and colocalization in a manner consistent with expression via transcription factories. We additionally use 2D phase planes to visualize patterns in 4DN data. Finally, we evaluated gene pairs within a circadian gene module using 3D imaging, and found periodicity in the movement of clock circadian regulator and period circadian clock 2 relative to each other that followed a circadian rhythm and entrained with their expression. PMID:26080430

  1. 4-D XRD for strain in many grains using triangulation

    SciTech Connect

    Bale, Hrishikesh A.; Hanan, Jay C.; Tamura, Nobumichi

    2006-12-31

    Determination of the strains in a polycrystalline materialusing 4-D XRD reveals sub-grain and grain-to-grain behavior as a functionof stress. Here 4-D XRD involves an experimental procedure usingpolychromatic micro-beam X-radiation (micro-Laue) to characterizepolycrystalline materials in spatial location as well as with increasingstress. The in-situ tensile loading experiment measured strain in a modelaluminum-sapphire metal matrix composite using the Advanced Light Source,Beam-line 7.3.3. Micro-Laue resolves individual grains in thepolycrystalline matrix. Results obtained from a list of grains sorted bycrystallographic orientation depict the strain states within and amongindividual grains. Locating the grain positions in the planeperpendicular to the incident beam is trivial. However, determining theexact location of grains within a 3-D space is challenging. Determiningthe depth of the grains within the matrix (along the beam direction)involved a triangulation method tracing individual rays that producespots on the CCD back to the point of origin. Triangulation wasexperimentally implemented by simulating a 3-D detector capturingmultiple diffraction images while increasing the camera to sampledistance. Hence by observing the intersection of rays from multiple spotsbelonging to the corresponding grain, depth is calculated. Depthresolution is a function of the number of images collected, grain to beamsize ratio, and the pixel resolution of the CCD. The 4DXRD methodprovides grain morphologies, strain behavior of each grain, andinteractions of the matrix grains with each other and the centrallylocated single crystal fiber.

  2. Deletion of phosphodiesterase 4D in mice shortens α2-adrenoceptor–mediated anesthesia, a behavioral correlate of emesis

    PubMed Central

    Robichaud, Annette; Stamatiou, Panagiota B.; Jin, S.-L.Catherine; Lachance, Nicholas; MacDonald, Dwight; Laliberté, France; Liu, Susana; Huang, Zheng; Conti, Marco; Chan, Chi-Chung

    2002-01-01

    A combination of pharmacological and genetic approaches was used to determine the role of type 4 cAMP-specific cyclic nucleotide phosphodiesterase 4 (PDE4) in reversing α2-adrenoceptor–mediated anesthesia, a behavioral correlate of emesis in non-vomiting species. Among the family-specific PDE inhibitors, PDE4 inhibitors reduced the duration of xylazine/ketamine–induced anesthesia in mice, with no effect on pentobarbital-induced anesthesia. The rank order of the PDE4 inhibitors tested was 6-(4-pyridylmethyl)-8-(3-nitrophenyl)quinoline (PMNPQ) > (R)-rolipram > (S)-rolipram >> (R)-N-{4-[1-(3-cyclopentyloxy-4-methoxyphenyl)-2-(4-pyridyl)ethyl]phenyl}N′-ethylurea (CT-2450). The specific roles of PDE4B and PDE4D in this model were studied using mice deficient in either subtype. PDE4D-deficient mice, but not PDE4B-deficient mice, had a shorter sleeping time than their wild-type littermates under xylazine/ketamine–induced anesthesia, but not under that induced with pentobarbital. Concomitantly, rolipram-sensitive PDE activity in the brain stem was decreased only in PDE4D-deficient mice compared with their wild-type littermates. While PMNPQ significantly reduced the xylazine/ketamine–induced anesthesia period in wild-type mice and in PDE4B-null mice, it had no effect in PDE4D-deficient mice. These findings strongly support the hypothesis that inhibition of PDE4D is pivotal to the anesthesia-reversing effect of PMNPQ and is likely responsible for emesis induced by PDE4 inhibitors. PMID:12370283

  3. Experimental evaluations of the accuracy of 3D and 4D planning in robotic tracking stereotactic body radiotherapy for lung cancers

    SciTech Connect

    Chan, Mark K. H.; Kwong, Dora L. W.; Ng, Sherry C. Y.; Tong, Anthony S. M.; Tam, Eric K. W.

    2013-04-15

    Purpose: Due to the complexity of 4D target tracking radiotherapy, the accuracy of this treatment strategy should be experimentally validated against established standard 3D technique. This work compared the accuracy of 3D and 4D dose calculations in respiration tracking stereotactic body radiotherapy (SBRT). Methods: Using the 4D planning module of the CyberKnife treatment planning system, treatment plans for a moving target and a static off-target cord structure were created on different four-dimensional computed tomography (4D-CT) datasets of a thorax phantom moving in different ranges. The 4D planning system used B-splines deformable image registrations (DIR) to accumulate dose distributions calculated on different breathing geometries, each corresponding to a static 3D-CT image of the 4D-CT dataset, onto a reference image to compose a 4D dose distribution. For each motion, 4D optimization was performed to generate a 4D treatment plan of the moving target. For comparison with standard 3D planning, each 4D plan was copied to the reference end-exhale images and a standard 3D dose calculation was followed. Treatment plans of the off-target structure were first obtained by standard 3D optimization on the end-exhale images. Subsequently, they were applied to recalculate the 4D dose distributions using DIRs. All dose distributions that were initially obtained using the ray-tracing algorithm with equivalent path-length heterogeneity correction (3D{sub EPL} and 4D{sub EPL}) were recalculated by a Monte Carlo algorithm (3D{sub MC} and 4D{sub MC}) to further investigate the effects of dose calculation algorithms. The calculated 3D{sub EPL}, 3D{sub MC}, 4D{sub EPL}, and 4D{sub MC} dose distributions were compared to measurements by Gafchromic EBT2 films in the axial and coronal planes of the moving target object, and the coronal plane for the static off-target object based on the {gamma} metric at 5%/3mm criteria ({gamma}{sub 5%/3mm}). Treatment plans were considered

  4. Head CT scan

    MedlinePlus

    Brain CT; Cranial CT; CT scan - skull; CT scan - head; CT scan - orbits; CT scan - sinuses; Computed tomography - cranial ... or other growth (mass) Cerebral atrophy (loss of brain tissue) ... with the hearing nerve Stroke or transient ischemic attack (TIA)

  5. 4D Light Field Imaging System Using Programmable Aperture

    NASA Technical Reports Server (NTRS)

    Bae, Youngsam

    2012-01-01

    Complete depth information can be extracted from analyzing all angles of light rays emanated from a source. However, this angular information is lost in a typical 2D imaging system. In order to record this information, a standard stereo imaging system uses two cameras to obtain information from two view angles. Sometimes, more cameras are used to obtain information from more angles. However, a 4D light field imaging technique can achieve this multiple-camera effect through a single-lens camera. Two methods are available for this: one using a microlens array, and the other using a moving aperture. The moving-aperture method can obtain more complete stereo information. The existing literature suggests a modified liquid crystal panel [LC (liquid crystal) panel, similar to ones commonly used in the display industry] to achieve a moving aperture. However, LC panels cannot withstand harsh environments and are not qualified for spaceflight. In this regard, different hardware is proposed for the moving aperture. A digital micromirror device (DMD) will replace the liquid crystal. This will be qualified for harsh environments for the 4D light field imaging. This will enable an imager to record near-complete stereo information. The approach to building a proof-ofconcept is using existing, or slightly modified, off-the-shelf components. An SLR (single-lens reflex) lens system, which typically has a large aperture for fast imaging, will be modified. The lens system will be arranged so that DMD can be integrated. The shape of aperture will be programmed for single-viewpoint imaging, multiple-viewpoint imaging, and coded aperture imaging. The novelty lies in using a DMD instead of a LC panel to move the apertures for 4D light field imaging. The DMD uses reflecting mirrors, so any light transmission lost (which would be expected from the LC panel) will be minimal. Also, the MEMS-based DMD can withstand higher temperature and pressure fluctuation than a LC panel can. Robotics need

  6. SU-E-J-31: Monitor Interfractional Variation of Tumor Respiratory Motion Using 4D KV Conebeam Computed Tomography for Stereotactic Body Radiation Therapy of Lung Cancer

    SciTech Connect

    Tai, A; Prior, P; Gore, E; Johnstone, C; Li, X

    2015-06-15

    Purpose: 4DCT has been widely used to generate internal tumor volume (ITV) for a lung tumor for treatment planning. However, lung tumors may show different respiratory motion on the treatment day. The purpose of this study is to evaluate 4D KV conebeam computed tomography (CBCT) for monitoring tumor interfractional motion variation between simulation and each fraction of stereotactic body radiation therapy (SBRT) for lung cancer. Methods: 4D KV CBCT was acquired with the Elekta XVI system. The accuracy of 4D KV CBCT for image-guided radiation therapy (IGRT) was tested with a dynamic thorax motion phantom (CIRS, Virginia) with a linear amplitude of 2 cm. In addition, an adult anthropomorphic phantom (Alderson, Rando) with optically stimulated luminescence (OSL) dosimeters embedded at the center and periphery of a slab of solid water was used to measure the dose of 4D KV CBCT and to compare it with the dose with 3D KV CBCT. The image registration was performed by aligning\\ each phase images of 4D KV CBCT to the planning images and the final couch shifts were calculated as a mean of all these individual shifts along each direction.A workflow was established based on these quality assurance tests for lung cancer patients. Results: 4D KV CBCT does not increase imaging dose in comparison to 3D KV CBCT. Acquisition of 4D KV CBCT is 4 minutes as compared to 2 minutes for 3D KV CBCT. Most of patients showed a small daily variation of tumor respiratory motion about 2 mm. However, some patients may have more than 5 mm variations of tumor respiratory motion. Conclusion: The radiation dose does not increase with 4D KV CBCT. 4D KV CBCT is a useful tool for monitoring interfractional variations of tumor respiratory motion before SBRT of lung cancer patients.

  7. High-Resolution Pyrimidine- and Ribose-Specific 4D HCCH-COSY Spectra of RNA Using the Filter Diagonalization Method

    PubMed Central

    Douglas, Justin T.; Latham, Michael P.; Armstrong, Geoffrey S.; Bendiak, Brad; Pardi, Arthur

    2010-01-01

    NMR spectra of nucleic acids suffer from severe peak overlap, which complicates resonance assignments. 4D NMR experiments can overcome much of the degeneracy in 2D and 3D spectra; however, the linear increase in acquisition time with each new dimension makes it impractical to acquire high-resolution 4D spectra using standard Fourier Transform (FT) techniques. The Filter Diagonalization Method (FDM) is a numerically efficient algorithm that fits the entire multi-dimensional time-domain data to a set of multi-dimensional oscillators. Selective 4D constant-time HCCH-COSY experiments that correlate the H5-C5-C6-H6 base spin systems of pyrimidines or the H1′-C1′-C2′-H2′ spin systems of ribose sugars were acquired on the 13C-labeled Iron Responsive Element RNA. FDM-processing of these 4D experiments recorded with only 8 complex points in the indirect dimensions showed superior spectral resolution than FT-processed spectra. Practical aspects of obtaining optimal FDM-processed spectra are discussed. The results here demonstrate that FDM-processing can be used to obtain high-resolution 4D spectra on a medium sized RNA in a fraction of the acquisition time normally required for high-resolution, high-dimensional spectra. PMID:18626775

  8. 4D prediction of protein (1)H chemical shifts.

    PubMed

    Lehtivarjo, Juuso; Hassinen, Tommi; Korhonen, Samuli-Petrus; Peräkylä, Mikael; Laatikainen, Reino

    2009-12-01

    A 4D approach for protein (1)H chemical shift prediction was explored. The 4th dimension is the molecular flexibility, mapped using molecular dynamics simulations. The chemical shifts were predicted with a principal component model based on atom coordinates from a database of 40 protein structures. When compared to the corresponding non-dynamic (3D) model, the 4th dimension improved prediction by 6-7%. The prediction method achieved RMS errors of 0.29 and 0.50 ppm for Halpha and HN shifts, respectively. However, for individual proteins the RMS errors were 0.17-0.34 and 0.34-0.65 ppm for the Halpha and HN shifts, respectively. X-ray structures gave better predictions than the corresponding NMR structures, indicating that chemical shifts contain invaluable information about local structures. The (1)H chemical shift prediction tool 4DSPOT is available from http://www.uku.fi/kemia/4dspot . PMID:19876601

  9. Chaos in a 4D dissipative nonlinear fermionic model

    NASA Astrophysics Data System (ADS)

    Aydogmus, Fatma

    2015-12-01

    Gursey Model is the only possible 4D conformally invariant pure fermionic model with a nonlinear self-coupled spinor term. It has been assumed to be similar to the Heisenberg's nonlinear generalization of Dirac's equation, as a possible basis for a unitary description of elementary particles. Gursey Model admits particle-like solutions for the derived classical field equations and these solutions are instantonic in character. In this paper, the dynamical nature of damped and forced Gursey Nonlinear Differential Equations System (GNDES) are studied in order to get more information on spinor type instantons. Bifurcation and chaos in the system are observed by constructing the bifurcation diagrams and Poincaré sections. Lyapunov exponent and power spectrum graphs of GNDES are also constructed to characterize the chaotic behavior.

  10. Data representation and visualization in 4-D microscopy

    NASA Astrophysics Data System (ADS)

    Kriete, Andres; Rohrbach, Steffen; Schwebel, Tim; Wagner, Hans-Joachim; Behrens, Uwe

    1992-09-01

    Computer representation in biological microscopy is progressing from the well established modeling of three-dimensional (3-D) structural information towards the visualization of spatio- temporal (4-D) information. This paper describes two new methods to process sequential volumes, where each data set corresponds to a time sample. The first technique is based on surface rendering to study organ and tissue development. Contour stacks are rendered and in- between stages are interpolated. This technique allows the analysis and simulation of growth following different mathematical models and relates them with experimental findings. The second technique got appreciation for volume rendering of morphogenesis in living tissue. Sequences scanned with a confocal microscope are packed. The combination of ray-casting reconstructions within a color model allows for a rendering of morphogenetic activity.

  11. 4D Script N = 2 supergravity and projective superspace

    NASA Astrophysics Data System (ADS)

    Kuzenko, S. M.; Lindström, U.; Rocek, M.; Tartaglino-Mazzucchelli, G.

    2008-09-01

    This paper presents a projective superspace formulation for 4D Script N = 2 matter-coupled supergravity. We first describe a variant superspace realization for the Script N = 2 Weyl multiplet. It differs from that proposed by Howe in 1982 by the choice of the structure group (SO(3,1) × SU(2) versus SO(3,1) × U(2)), which implies that the super-Weyl transformations are generated by a covariantly chiral parameter instead of a real unconstrained one. We introduce various off-shell supermultiplets which are curved superspace analogues of the superconformal projective multiplets in global supersymmetry and which describe matter fields coupled to supergravity. A manifestly locally supersymmetric and super-Weyl invariant action principle is given. Off-shell locally supersymmetric nonlinear sigma models are presented in this new superspace.

  12. Mechanical properties of 4d transition metals in molten state

    NASA Astrophysics Data System (ADS)

    Singh, Deobrat; Sonvane, Yogesh; Thakor, P. B.

    2016-05-01

    Mechanical properties of 4d transition metals in molten state have been studied in the present study. We have calculated mechanical properties such as isothermal bulk modulus (B), modulus of rigidity (G), Young's modulus (Y) and Hardness have also been calculated from the elastic part of the Phonon dispersion curve (PDC). To describe the structural information, we have used different structure factor S(q) using Percus-Yevick hard sphere (PYHS) reference systems along with our newly constructed parameter free model potential.To see the influence of exchange and correlation effect on the above said properties of 3d liquid transition metals, we have used Sarkar et al (S)local field correction functions. Present results have been found good in agreement with available experimental data.

  13. Immersive 4-D Interactive Visualization of Large-Scale Simulations

    NASA Astrophysics Data System (ADS)

    Teuben, P. J.; Hut, P.; Levy, S.; Makino, J.; McMillan, S.; Portegies Zwart, S.; Shara, M.; Emmart, C.

    In dense clusters a bewildering variety of interactions between stars can be observed, ranging from simple encounters to collisions and other mass-transfer encounters. With faster and special-purpose computers like GRAPE, the amount of data per simulation is now exceeding 1 TB. Visualization of such data has now become a complex 4-D data-mining problem, combining space and time, and finding interesting events in these large datasets. We have recently starting using the virtual reality simulator, installed in the Hayden Planetarium in the American Museum for Natural History, to tackle some of these problem. This work reports on our first ``observations,'' modifications needed for our specific experiments, and perhaps field ideas for other fields in science which can benefit from such immersion. We also discuss how our normal analysis programs can be interfaced with this kind of visualization.

  14. Cine CT technique for dynamic airway studies

    SciTech Connect

    Ell, S.R.; Jolles, H.; Keyes, W.D.; Galvin, J.R.

    1985-07-01

    The advent of cine CT scanning with its 50-msec data acquisition time promises a much wider range of dynamic CT studies. The authors describe a method for dynamic evaluation of the extrathoracic airway, which they believe has considerable potential application in nonfixed upper-airway disease, such as sleep apnea and stridor of unknown cause. Conventional CT is limited in such studies by long data acquisition time and can be used to study only prolonged maneuvers such as phonation. Fluoroscopy and digital subtraction studies are limited by relatively high radiation dose and inability to image all wall motions simultaneously.

  15. MCAT to XCAT: The Evolution of 4-D Computerized Phantoms for Imaging Research

    PubMed Central

    Paul Segars, W.; Tsui, Benjamin M. W.

    2012-01-01

    Recent work in the development of computerized phantoms has focused on the creation of ideal “hybrid” models that seek to combine the realism of a patient-based voxelized phantom with the flexibility of a mathematical or stylized phantom. We have been leading the development of such computerized phantoms for use in medical imaging research. This paper will summarize our developments dating from the original four-dimensional (4-D) Mathematical Cardiac-Torso (MCAT) phantom, a stylized model based on geometric primitives, to the current 4-D extended Cardiac-Torso (XCAT) and Mouse Whole-Body (MOBY) phantoms, hybrid models of the human and laboratory mouse based on state-of-the-art computer graphics techniques. This paper illustrates the evolution of computerized phantoms toward more accurate models of anatomy and physiology. This evolution was catalyzed through the introduction of nonuniform rational b-spline (NURBS) and subdivision (SD) surfaces, tools widely used in computer graphics, as modeling primitives to define a more ideal hybrid phantom. With NURBS and SD surfaces as a basis, we progressed from a simple geometrically based model of the male torso (MCAT) containing only a handful of structures to detailed, whole-body models of the male and female (XCAT) anatomies (at different ages from newborn to adult), each containing more than 9000 structures. The techniques we applied for modeling the human body were similarly used in the creation of the 4-D MOBY phantom, a whole-body model for the mouse designed for small animal imaging research. From our work, we have found the NURBS and SD surface modeling techniques to be an efficient and flexible way to describe the anatomy and physiology for realistic phantoms. Based on imaging data, the surfaces can accurately model the complex organs and structures in the body, providing a level of realism comparable to that of a voxelized phantom. In addition, they are very flexible. Like stylized models, they can easily be

  16. Unusual Pulmonary Arterial Filling Defect caused by Systemic to Pulmonary Shunt in the Setting of Chronic Lung Disease Demonstrated by Dynamic 4D CTA

    PubMed Central

    Ansari-Gilani, Kianoush; Gilkeson, Robert C; Hsiao, Edward M; Rajiah, Prabhakar

    2015-01-01

    Even though pulmonary embolism is by far the most common cause of filling defect in the pulmonary arterial system, other less common etiologies should be considered especially in the setting of atypical clinical scenario or unusual imaging findings. Unusual pattern of filling defect in the pulmonary artery in the setting of chronic inflammatory/fibrotic parenchymal lung disease should raise the concern for systemic to pulmonary artery shunt. This diagnosis is typically made by conventional angiography. Dynamic 4D CT angiography however can be a safe, noninvasive and effective alternative tool for making such a diagnosis. It has the added value of multiplanar reconstruction capabilities and providing detailed anatomy which can be vital for interventional radiologists when planning their approach for possible intervention. We present 2 cases of such shunts, and illustrate the demonstration of these shunts by using dynamic 4D CT angiography. PMID:27252791

  17. Towards a Virtual 4D Data Cube for Near Real-Time Applications

    NASA Astrophysics Data System (ADS)

    Nguyen, L.; Minnis, P.; Palikonda, R.; Chee, T.; Nelson, M. L.

    2011-12-01

    One of the great challenges for many Near Real-Time (NRT) geophysical applications is accessing data and services in a efficient and timely manner across heterogeneous and distributed systems. Applications that rely on NRT input data are at the mercy of the provider to make the data available as soon as possible and make them accessible in a common format and acceptable protocol. NRT applications such as the NOAA Rapid Refresh model (RR) and the NCAR Current Icing Potential (CIP) are currently using and relying on NRT satellite derived clouds products produced by the NASA Langley (LaRC) Cloud and Radiation Group (CRG). The LaRC CRG data acquisition, processing, and dissemination framework is capable of producing these products 15-25 minutes after the nominal satellite image time. The slightest delay in generating these cloud products can result in compound delays for the NRT applications using it. These delays can be attributed to factors associated with ingestion, processing, and staging of the data. Multi-core processors and parallel computing can improve processing delay, however, ingestion and staging delays will contribute to the majority of this delay. Thus, the LaRC CRG will embark on a proposed net-centric designed and development of a virtual 4D data cube for storing real-time geospatial data and products produced by various NRT applications. This data cube will integrate and fuse data, at the pixel-level, into a common environment and framework. It will provide standard interoperable tools for sharing, accessing, and querying data. This approach will enable algorithms or applications to query pixel data, process it, and inject the product back into the data cube without ingest or staging delays and thus making it immediately available to the end-user in real-time. This paper identifies technologies being evaluated for future use and describes the data and product flow in this 4D data cube environment.

  18. Validation of CT doses of SPECT/CT and PET/CT hybrid devices: lessons learned.

    PubMed

    Sera, Terez; Porubszky, Tamas; Papos, Miklos; Elek, Richard; Besenyi, Zsuzsanna; Gion, Katalin; Bartha, Andras; Pellet, Sandor; Pavics, Laszlo

    2014-05-01

    The aim of the study was to check the validity of computed tomographic (CT) doses exhibited by SPECT/CT and PET/CT hybrid devices. Dose measurements were taken from four SPECT/CT and four PET/CT cameras commercially available from different manufacturers. A calibrated ionization chamber was placed in whole-body or head phantoms for the acquisition of CT images with clinically used parameters. Computed tomography dose index (CTDIvol) values were calculated according to the IEC 60601-2-44:1999 formula. The measured CTDIvol doses were compared with those preprogrammed by the manufacturer. In the case of the whole-body phantom, the differences between the measured and displayed values varied between -31 and +24% [European document RP162 (2012) sets up the limit for acceptance criterion as ±20%]. The head phantom data showed either an agreement between -10 and +24%, or an underestimation by two-fold. The latter seemed to be because, while preprogramming the doses, the manufacturer had used the whole-body phantom instead of a proper head phantom. The results of the work demonstrate the need for individual dosimetric calibration of every single X-ray tube. Dosimetric checks should be included in the regular quality control programmes of the SPECT/CT and PET/CT devices. Special attention should be paid to head-and-neck and paediatric protocols, in which the use of a head phantom is recommended for dose calibration. PMID:24499726

  19. SU-D-17A-01: Geometric and Dosimetric Evaluation of a 4D-CBCT Reconstruction Technique Using Prior Knowledge

    SciTech Connect

    Zhang, Y; Yin, F; Ren, L

    2014-06-01

    Purpose: To evaluate a 4D-CBCT reconstruction technique both geometrically and dosimetrically Methods: A prior-knowledge guided 4DC-BCT reconstruction method named the motion-modeling and free-form deformation (MM-FD) has been developed. MM-FD views each phase of the 4D-CBCT as a deformation of a prior CT volume. The deformation field is first solved by principal component analysis based motion modeling, followed by constrained free-form deformation.The 4D digital extended-cardiac- torso (XCAT) phantom was used for comprehensive evaluation. Based on a simulated 4D planning CT of a lung patient, 8 different scenarios were simulated to cover the typical on-board anatomical and respiratory variations: (1) synchronized and (2) unsynchronized motion amplitude change for body and tumor; tumor (3) shrinkage and (4) expansion; tumor average position shift in (5) superior-inferior (SI) direction, (6) anterior-posterior (AP) direction and (7) SI, AP and lateral directions altogether; and (8) tumor phase shift relative to the respiratory cycle of the body. Orthogonal-view 30° projections were simulated based on the eight patient scenarios to reconstruct on-board 4D-CBCTs. For geometric evaluation, the volume-percentage-difference (VPD) was calculated to assess the volumetric differences between the reconstructed and the ground-truth tumor.For dosimetric evaluation, a gated treatment plan was designed for the prior 4D-CT. The dose distributions were calculated on the reconstructed 4D-CBCTs and the ground-truth images for comparison. The MM-FD technique was compared with MM-only and FD-only techniques. Results: The average (±s.d.) VPD values of reconstructed tumors for MM-only, FDonly and MM-FD methods were 59.16%(± 26.66%), 75.98%(± 27.21%) and 5.22%(± 2.12%), respectively. The average min/max/mean dose (normalized to prescription) of the reconstructed tumors by MM-only, FD-only, MM-FD methods and ground-truth tumors were 78.0%/122.2%/108.2%, 13%/117.7%/86%, 58

  20. 4D Dynamic RNP Annual Interim Report-Year 1

    NASA Technical Reports Server (NTRS)

    Finkelsztein, Daniel M.; Sturdy, James L.; Alaverdi, Omeed; Chung, William W.; Salvano, Daniel; Klooster, Joel; Hochwarth, Joachim K.

    2010-01-01

    This Annual Interim Report summarizes the activities led by Raytheon, in collaboration with GE Aviation and SAIC, and presents the results obtained during the first year of this research effort to expand the RNP concept to 4 dimensions relative to a dynamic frame of reference. Joint Program Development Office (JPDO)Concepts of Operations for the Next Generation Air Transportation System (NextGen) considers 4 Dimension Trajectory (4DT) procedures a key enabler to Trajectory Based Operations (TBO). The JPDO defines 4DT as a precise description of an aircraft path in space and time . While NextGen assumes that this path is defined within an Earth-reference frame, many 4DT procedure implementations will require an aircraft to precisely navigate relative to a moving reference such as another aircraft to form aggregate flows or a weather cell to allow for flows to shift. Current methods of implementing routes and flight paths rely on aircraft meeting a Required Navigation Performance (RNP) specification and being equipped with a monitoring and alerting capability to annunciate when the aircraft system is unable to meet the performance specification required for the operation. Since all aircraft today operate within the NAS relative to fixed reference points, the current RNP definition is deemed satisfactory. However, it is not well understood how the current RNP construct will support NextGen 4DT procedures where aircraft operate relative to each other or to other dynamic frames of reference. The objective of this research effort is to analyze candidate 4DT procedures from both an Air Navigation Service Provider (ANSP) and aircraft perspective, to identify their specific navigational requirements, assess the shortcomings of the current RNP construct to meet these requirements, to propose an extended 4 Dimensional Dynamic RNP (4D Dynamic RNP) construct that accounts for the dynamic spatial and temporal nature of the selected 4DT procedures, and finally, to design an

  1. Formation of secondary porosity in 4D Synchrotron X-ray tomography experiments

    NASA Astrophysics Data System (ADS)

    Fusseis, Florian; Liu, Jie; de Carlo, Francesco; Regenauer-Lieb, Klaus; Schrank, Christoph; Hough, Robert; Gessner, Klaus; Llana-Fúnez, Sergio; Faulkner, Dan; Wheeler, John

    2010-05-01

    Synchrotron X-ray tomography at the Advanced Photon Source (APS) allows to investigate secondary porosity in three dimensions on the nano- to microscale. We utilised the key advantage of the technique, the rapid data acquisition time (seconds to about half an hour/data set), to study the formation of porosity in natural rock samples in real time (4D). The spacious instrument setup in the experimental hutch allowed us to install an X-ray transparent furnace to heat millimetre-sized samples up to 230 °C (>400 °C in the next generation) in the X-ray beam. We focused on two porosity-generating mechanisms: thermal expansion cracking in Westerly granite and dehydration (volume loss/hydraulic fracturing) of Volterra gypsum. The spatial resolution was 1.3 micron in both experiments. We heated a 2mm diameter cylinder of Westerly Granite stepwise from 50 °C to 230 °C and then quenched it to investigate the effects of thermal expansion cracking on the three-dimensional porosity architecture. The sample was scanned after increasing the temperature in 10 °C steps to record the cracks formed during each heating interval. Preliminary analysis of the heterogeneous 4D displacement fields proved that the approach works well. We documented the opening and closing as well as interconnection of grain boundary- and intragranular cracks. A full quantification is currently under way. This experiment also serves to benchmark numerical simulations of thermal cracking that will be used to upscale the permeability evolution during heating (see abstract of Schrank et al.). A second heating experiment aimed at documenting the fluid escape pathways during the dehydration of gypsum to bassanite. We heated a gypsum sample to 115 °C for increasing periods of time. The reaction progress was directly observed in two-dimensional tomographic projections, 3D tomographic datasets were collected during cooling at 50 °C in between the heating intervals. The experiment demonstrated how a permeable

  2. 4D multiple-cathode ultrafast electron microscopy

    PubMed Central

    Baskin, John Spencer; Liu, Haihua; Zewail, Ahmed H.

    2014-01-01

    Four-dimensional multiple-cathode ultrafast electron microscopy is developed to enable the capture of multiple images at ultrashort time intervals for a single microscopic dynamic process. The dynamic process is initiated in the specimen by one femtosecond light pulse and probed by multiple packets of electrons generated by one UV laser pulse impinging on multiple, spatially distinct, cathode surfaces. Each packet is distinctly recorded, with timing and detector location controlled by the cathode configuration. In the first demonstration, two packets of electrons on each image frame (of the CCD) probe different times, separated by 19 picoseconds, in the evolution of the diffraction of a gold film following femtosecond heating. Future elaborations of this concept to extend its capabilities and expand the range of applications of 4D ultrafast electron microscopy are discussed. The proof-of-principle demonstration reported here provides a path toward the imaging of irreversible ultrafast phenomena of materials, and opens the door to studies involving the single-frame capture of ultrafast dynamics using single-pump/multiple-probe, embedded stroboscopic imaging. PMID:25006261

  3. Reduced order POD/DEIM 4-D Var data assimilation

    NASA Astrophysics Data System (ADS)

    Navon, Michael; Stefanescu, Razvan

    2014-05-01

    The computational cost of realistic ensemble and hybrid variational/ensemble data assimilation is typically dominated by the cost of ensemble forecasting. The high computational cost of ensemble forecasting limits the number of ensembles, eventually creating a severe rank reduction. Consequently, the efficiency and quality of ensemble-based data assimilation are greatly reduced. With the ever-increasing spatiotemporal resolution and complexity of numerical weather prediction (NWP) models, the room for ensemble forecasting is getting even smaller, creating a paradox: Although the NWP generally benefits from increased resolution and complexity of the models, the quality of their data assimilation is getting worse due to additional computational restrictions. We propose POD model order reduction substantially improving computational efficiency of NWP models. We present recent advances in this domain and the state-of the art of hyper reduction addressing issues of turbulence closure and nonlinearities allowing CPU speed -ups of orders of magnitude, reduced order 4-D VAR and future prospects of implementation to operational NMP models.

  4. Multimaterial 4D Printing with Tailorable Shape Memory Polymers

    PubMed Central

    Ge, Qi; Sakhaei, Amir Hosein; Lee, Howon; Dunn, Conner K.; Fang, Nicholas X.; Dunn, Martin L.

    2016-01-01

    We present a new 4D printing approach that can create high resolution (up to a few microns), multimaterial shape memory polymer (SMP) architectures. The approach is based on high resolution projection microstereolithography (PμSL) and uses a family of photo-curable methacrylate based copolymer networks. We designed the constituents and compositions to exhibit desired thermomechanical behavior (including rubbery modulus, glass transition temperature and failure strain which is more than 300% and larger than any existing printable materials) to enable controlled shape memory behavior. We used a high resolution, high contrast digital micro display to ensure high resolution of photo-curing methacrylate based SMPs that requires higher exposure energy than more common acrylate based polymers. An automated material exchange process enables the manufacture of 3D composite architectures from multiple photo-curable SMPs. In order to understand the behavior of the 3D composite microarchitectures, we carry out high fidelity computational simulations of their complex nonlinear, time-dependent behavior and study important design considerations including local deformation, shape fixity and free recovery rate. Simulations are in good agreement with experiments for a series of single and multimaterial components and can be used to facilitate the design of SMP 3D structures. PMID:27499417

  5. 4D MRI of renal function in the developing mouse

    PubMed Central

    Xie, Luke; Subashi, Ergys; Qi, Yi; Knepper, Mark A.; Johnson, G. Allan

    2014-01-01

    The major roles of filtration, metabolism, and high blood flow make the kidney highly vulnerable to drug-induced toxicity and other renal injuries. A method to follow kidney function is essential for early screening of toxicity and malformations. In this study, we acquired high spatiotemporal resolution (4D) datasets of normal mice to follow changes in kidney structure and function during development. The data were acquired with dynamic contrast-enhanced MRI (via keyhole imaging) and a cryogenic surface coil, allowing us to obtain a full 3D image (125-micron isotropic resolution) every 7.7 seconds over a 50-minute scan. This time course permitted demonstration of both contrast enhancement and clearance. Functional changes were measured over a 17-week course (at 3, 5, 7, 9, 13, and 17 weeks). The time dimension of the MRI dataset was processed to produce unique image contrasts for segmenting the 4 regions of the kidney: cortex (CO), outer stripe (OS) of the outer medulla (OM), inner stripe (IS) of the OM, and inner medulla (IM). Local volumes, time-to-peak (TTP) values, and decay constants (DC) were measured in each renal region. These metrics increased significantly with age, with the exception of DC values in the IS and OS. These data will serve as a foundation for studies of normal renal physiology and future studies of renal diseases that require early detection and intervention. PMID:25066408

  6. Multimaterial 4D Printing with Tailorable Shape Memory Polymers

    NASA Astrophysics Data System (ADS)

    Ge, Qi; Sakhaei, Amir Hosein; Lee, Howon; Dunn, Conner K.; Fang, Nicholas X.; Dunn, Martin L.

    2016-08-01

    We present a new 4D printing approach that can create high resolution (up to a few microns), multimaterial shape memory polymer (SMP) architectures. The approach is based on high resolution projection microstereolithography (PμSL) and uses a family of photo-curable methacrylate based copolymer networks. We designed the constituents and compositions to exhibit desired thermomechanical behavior (including rubbery modulus, glass transition temperature and failure strain which is more than 300% and larger than any existing printable materials) to enable controlled shape memory behavior. We used a high resolution, high contrast digital micro display to ensure high resolution of photo-curing methacrylate based SMPs that requires higher exposure energy than more common acrylate based polymers. An automated material exchange process enables the manufacture of 3D composite architectures from multiple photo-curable SMPs. In order to understand the behavior of the 3D composite microarchitectures, we carry out high fidelity computational simulations of their complex nonlinear, time-dependent behavior and study important design considerations including local deformation, shape fixity and free recovery rate. Simulations are in good agreement with experiments for a series of single and multimaterial components and can be used to facilitate the design of SMP 3D structures.

  7. "4D Biology for health and disease" workshop report.

    PubMed

    Abrahams, Jan-Pieter; Apweiler, Rolf; Balling, Rudi; Bertero, Michela G; Bujnicki, Janusz M; Chayen, Naomi E; Chène, Patrick; Corthals, Gary L; Dyląg, Tomasz; Förster, Friedrich; Heck, Albert J R; Henderson, Peter J F; Herwig, Ralf; Jehenson, Philippe; Kokalj, Sasa Jenko; Laue, Ernest; Legrain, Pierre; Martens, Lennart; Migliorini, Cristiano; Musacchio, Andrea; Podobnik, Marjetka; Schertler, Gebhard F X; Schreiber, Gideon; Sixma, Titia K; Smit, August B; Stuart, David; Svergun, Dmitri I; Taussig, Michael J

    2011-07-01

    The "4D Biology Workshop for Health and Disease", held on 16-17th of March 2010 in Brussels, aimed at finding the best organising principles for large-scale proteomics, interactomics and structural genomics/biology initiatives, and setting the vision for future high-throughput research and large-scale data gathering in biological and medical science. Major conclusions of the workshop include the following. (i) Development of new technologies and approaches to data analysis is crucial. Biophysical methods should be developed that span a broad range of time/spatial resolution and characterise structures and kinetics of interactions. Mathematics, physics, computational and engineering tools need to be used more in biology and new tools need to be developed. (ii) Database efforts need to focus on improved definitions of ontologies and standards so that system-scale data and associated metadata can be understood and shared efficiently. (iii) Research infrastructures should play a key role in fostering multidisciplinary research, maximising knowledge exchange between disciplines and facilitating access to diverse technologies. (iv) Understanding disease on a molecular level is crucial. System approaches may represent a new paradigm in the search for biomarkers and new targets in human disease. (v) Appropriate education and training should be provided to help efficient exchange of knowledge between theoreticians, experimental biologists and clinicians. These conclusions provide a strong basis for creating major possibilities in advancing research and clinical applications towards personalised medicine. PMID:20951846

  8. Analytical and numerical manifolds in a symplectic 4-D map

    NASA Astrophysics Data System (ADS)

    Delis, N.; Contopoulos, G.

    2016-05-01

    We study analytically the orbits along the asymptotic manifolds from a complex unstable periodic orbit in a symplectic 4-D Froeschlé map. The orbits are given as convergent series. We compare the analytic results by truncating the series at various orders with the corresponding numerical results and we find agreement along a more extended length, as the order of truncation increases. The agreement is improved when the parameters approach those of the stability domain. Along the manifolds no terms with small divisors appear in the series. The same result is found if we use a parametrization method along the asymptotic curves. In the case of orbits starting close to the manifolds small divisors appear, but the orbits remain close to the manifolds for an extended period of time. If the parameters of the map are close to the stable domain the orbits recede and approach the origin several times and remain confined in a certain volume around the origin for a long time before escaping to large distances. For special sets of parameters we see resonance phenomena and the orbits take particular forms near every resonance.

  9. Multimaterial 4D Printing with Tailorable Shape Memory Polymers.

    PubMed

    Ge, Qi; Sakhaei, Amir Hosein; Lee, Howon; Dunn, Conner K; Fang, Nicholas X; Dunn, Martin L

    2016-01-01

    We present a new 4D printing approach that can create high resolution (up to a few microns), multimaterial shape memory polymer (SMP) architectures. The approach is based on high resolution projection microstereolithography (PμSL) and uses a family of photo-curable methacrylate based copolymer networks. We designed the constituents and compositions to exhibit desired thermomechanical behavior (including rubbery modulus, glass transition temperature and failure strain which is more than 300% and larger than any existing printable materials) to enable controlled shape memory behavior. We used a high resolution, high contrast digital micro display to ensure high resolution of photo-curing methacrylate based SMPs that requires higher exposure energy than more common acrylate based polymers. An automated material exchange process enables the manufacture of 3D composite architectures from multiple photo-curable SMPs. In order to understand the behavior of the 3D composite microarchitectures, we carry out high fidelity computational simulations of their complex nonlinear, time-dependent behavior and study important design considerations including local deformation, shape fixity and free recovery rate. Simulations are in good agreement with experiments for a series of single and multimaterial components and can be used to facilitate the design of SMP 3D structures. PMID:27499417

  10. Insight into water molecules bonding on 4d metal surfaces

    NASA Astrophysics Data System (ADS)

    Carrasco, Javier; Michaelides, Angelos; Scheffler, Matthias

    2008-03-01

    Water-metal interactions are of capital importance to a wide variety of phenomena in materials science, catalysis, corrosion, electrochemistry, etc. Here we address the nature of the bond between water molecules and metal surfaces through a careful systematic study. Specifically, the bonding of isolated water molecules to a series of close-packed transition metal surfaces - Ru(0001), Rh(111), Pd(111) and Ag(111) - has been examined in detail with density functional theory (DFT). Aiming to understand the origin behind energetic and structural trends along the 4d series we employ a range of analysis tools, such as decomposition of the density of states, electron density differences, electronic reactivity function and inspection of individual Kohn-Sham orbitals. The results obtained allow us to rationalize the bonding between water and transition metal surfaces as a balance of covalent and electrostatic interactions. A frontier orbital scheme based on so-called two-center four-electron interactions between molecular orbitals of water and d band states of the surface proves incisive in understanding these systems.

  11. Estimating Myocardial Motion by 4D Image Warping

    PubMed Central

    Sundar, Hari; Litt, Harold; Shen, Dinggang

    2009-01-01

    A method for spatio-temporally smooth and consistent estimation of cardiac motion from MR cine sequences is proposed. Myocardial motion is estimated within a 4-dimensional (4D) registration framework, in which all 3D images obtained at different cardiac phases are simultaneously registered. This facilitates spatio-temporally consistent estimation of motion as opposed to other registration-based algorithms which estimate the motion by sequentially registering one frame to another. To facilitate image matching, an attribute vector (AV) is constructed for each point in the image, and is intended to serve as a “morphological signature” of that point. The AV includes intensity, boundary, and geometric moment invariants (GMIs). Hierarchical registration of two image sequences is achieved by using the most distinctive points for initial registration of two sequences and gradually adding less-distinctive points to refine the registration. Experimental results on real data demonstrate good performance of the proposed method for cardiac image registration and motion estimation. The motion estimation is validated via comparisons with motion estimates obtained from MR images with myocardial tagging. PMID:20379351

  12. Temporally coherent 4D video segmentation for teleconferencing

    NASA Astrophysics Data System (ADS)

    Ehmann, Jana; Guleryuz, Onur G.

    2013-09-01

    We develop an algorithm for 4-D (RGB+Depth) video segmentation targeting immersive teleconferencing ap- plications on emerging mobile devices. Our algorithm extracts users from their environments and places them onto virtual backgrounds similar to green-screening. The virtual backgrounds increase immersion and interac- tivity, relieving the users of the system from distractions caused by disparate environments. Commodity depth sensors, while providing useful information for segmentation, result in noisy depth maps with a large number of missing depth values. By combining depth and RGB information, our work signi¯cantly improves the other- wise very coarse segmentation. Further imposing temporal coherence yields compositions where the foregrounds seamlessly blend with the virtual backgrounds with minimal °icker and other artifacts. We achieve said improve- ments by correcting the missing information in depth maps before fast RGB-based segmentation, which operates in conjunction with temporal coherence. Simulation results indicate the e±cacy of the proposed system in video conferencing scenarios.

  13. 2,4-D and IAA Amino Acid Conjugates Show Distinct Metabolism in Arabidopsis

    PubMed Central

    Eyer, Luděk; Vain, Thomas; Pařízková, Barbora; Oklestkova, Jana; Barbez, Elke; Kozubíková, Hana; Pospíšil, Tomáš; Wierzbicka, Roksana; Kleine-Vehn, Jürgen; Fránek, Milan; Strnad, Miroslav; Robert, Stéphanie

    2016-01-01

    The herbicide 2,4-D exhibits an auxinic activity and therefore can be used as a synthetic and traceable analog to study auxin-related responses. Here we identified that not only exogenous 2,4-D but also its amide-linked metabolite 2,4-D-Glu displayed an inhibitory effect on plant growth via the TIR1/AFB auxin-mediated signaling pathway. To further investigate 2,4-D metabolite conversion, identity and activity, we have developed a novel purification procedure based on the combination of ion exchange and immuno-specific sorbents combined with a sensitive liquid chromatography-mass spectrometry method. In 2,4-D treated samples, 2,4-D-Glu and 2,4-D-Asp were detected at 100-fold lower concentrations compared to 2,4-D levels, showing that 2,4-D can be metabolized in the plant. Moreover, 2,4-D-Asp and 2,4-D-Glu were identified as reversible forms of 2,4-D homeostasis that can be converted to free 2,4-D. This work paves the way to new studies of auxin action in plant development. PMID:27434212

  14. Automatic 4D Reconstruction of Patient-Specific Cardiac Mesh with 1-to-1 Vertex Correspondence from Segmented Contours Lines

    PubMed Central

    Lim, Chi Wan; Su, Yi; Yeo, Si Yong; Ng, Gillian Maria; Nguyen, Vinh Tan; Zhong, Liang; Tan, Ru San; Poh, Kian Keong; Chai, Ping

    2014-01-01

    We propose an automatic algorithm for the reconstruction of patient-specific cardiac mesh models with 1-to-1 vertex correspondence. In this framework, a series of 3D meshes depicting the endocardial surface of the heart at each time step is constructed, based on a set of border delineated magnetic resonance imaging (MRI) data of the whole cardiac cycle. The key contribution in this work involves a novel reconstruction technique to generate a 4D (i.e., spatial–temporal) model of the heart with 1-to-1 vertex mapping throughout the time frames. The reconstructed 3D model from the first time step is used as a base template model and then deformed to fit the segmented contours from the subsequent time steps. A method to determine a tree-based connectivity relationship is proposed to ensure robust mapping during mesh deformation. The novel feature is the ability to handle intra- and inter-frame 2D topology changes of the contours, which manifests as a series of merging and splitting of contours when the images are viewed either in a spatial or temporal sequence. Our algorithm has been tested on five acquisitions of cardiac MRI and can successfully reconstruct the full 4D heart model in around 30 minutes per subject. The generated 4D heart model conforms very well with the input segmented contours and the mesh element shape is of reasonably good quality. The work is important in the support of downstream computational simulation activities. PMID:24743555

  15. Ultra-low dose CT attenuation correction for PET/CT

    NASA Astrophysics Data System (ADS)

    Xia, Ting; Alessio, Adam M.; De Man, Bruno; Manjeshwar, Ravindra; Asma, Evren; Kinahan, Paul E.

    2012-01-01

    A challenge for positron emission tomography/computed tomography (PET/CT) quantitation is patient respiratory motion, which can cause an underestimation of lesion activity uptake and an overestimation of lesion volume. Several respiratory motion correction methods benefit from longer duration CT scans that are phase matched with PET scans. However, even with the currently available, lowest dose CT techniques, extended duration cine CT scans impart a substantially high radiation dose. This study evaluates methods designed to reduce CT radiation dose in PET/CT scanning. We investigated selected combinations of dose reduced acquisition and noise suppression methods that take advantage of the reduced requirement of CT for PET attenuation correction (AC). These include reducing CT tube current, optimizing CT tube voltage, adding filtration, CT sinogram smoothing and clipping. We explored the impact of these methods on PET quantitation via simulations on different digital phantoms. CT tube current can be reduced much lower for AC than that in low dose CT protocols. Spectra that are higher energy and narrower are generally more dose efficient with respect to PET image quality. Sinogram smoothing could be used to compensate for the increased noise and artifacts at radiation dose reduced CT images, which allows for a further reduction of CT dose with no penalty for PET image quantitation. When CT is not used for diagnostic and anatomical localization purposes, we showed that ultra-low dose CT for PET/CT is feasible. The significant dose reduction strategies proposed here could enable respiratory motion compensation methods that require extended duration CT scans and reduce radiation exposure in general for all PET/CT imaging.

  16. Whole-body direct 4D parametric PET imaging employing nested generalized Patlak expectation–maximization reconstruction

    NASA Astrophysics Data System (ADS)

    Karakatsanis, Nicolas A.; Casey, Michael E.; Lodge, Martin A.; Rahmim, Arman; Zaidi, Habib

    2016-08-01

    Whole-body (WB) dynamic PET has recently demonstrated its potential in translating the quantitative benefits of parametric imaging to the clinic. Post-reconstruction standard Patlak (sPatlak) WB graphical analysis utilizes multi-bed multi-pass PET acquisition to produce quantitative WB images of the tracer influx rate K i as a complimentary metric to the semi-quantitative standardized uptake value (SUV). The resulting K i images may suffer from high noise due to the need for short acquisition frames. Meanwhile, a generalized Patlak (gPatlak) WB post-reconstruction method had been suggested to limit K i bias of sPatlak analysis at regions with non-negligible 18F-FDG uptake reversibility; however, gPatlak analysis is non-linear and thus can further amplify noise. In the present study, we implemented, within the open-source software for tomographic image reconstruction platform, a clinically adoptable 4D WB reconstruction framework enabling efficient estimation of sPatlak and gPatlak images directly from dynamic multi-bed PET raw data with substantial noise reduction. Furthermore, we employed the optimization transfer methodology to accelerate 4D expectation–maximization (EM) convergence by nesting the fast image-based estimation of Patlak parameters within each iteration cycle of the slower projection-based estimation of dynamic PET images. The novel gPatlak 4D method was initialized from an optimized set of sPatlak ML-EM iterations to facilitate EM convergence. Initially, realistic simulations were conducted utilizing published 18F-FDG kinetic parameters coupled with the XCAT phantom. Quantitative analyses illustrated enhanced K i target-to-background ratio (TBR) and especially contrast-to-noise ratio (CNR) performance for the 4D versus the indirect methods and static SUV. Furthermore, considerable convergence acceleration was observed for the nested algorithms involving 10–20 sub-iterations. Moreover, systematic reduction in K i % bias and improved TBR were

  17. Whole-body direct 4D parametric PET imaging employing nested generalized Patlak expectation-maximization reconstruction.

    PubMed

    Karakatsanis, Nicolas A; Casey, Michael E; Lodge, Martin A; Rahmim, Arman; Zaidi, Habib

    2016-08-01

    Whole-body (WB) dynamic PET has recently demonstrated its potential in translating the quantitative benefits of parametric imaging to the clinic. Post-reconstruction standard Patlak (sPatlak) WB graphical analysis utilizes multi-bed multi-pass PET acquisition to produce quantitative WB images of the tracer influx rate K i as a complimentary metric to the semi-quantitative standardized uptake value (SUV). The resulting K i images may suffer from high noise due to the need for short acquisition frames. Meanwhile, a generalized Patlak (gPatlak) WB post-reconstruction method had been suggested to limit K i bias of sPatlak analysis at regions with non-negligible (18)F-FDG uptake reversibility; however, gPatlak analysis is non-linear and thus can further amplify noise. In the present study, we implemented, within the open-source software for tomographic image reconstruction platform, a clinically adoptable 4D WB reconstruction framework enabling efficient estimation of sPatlak and gPatlak images directly from dynamic multi-bed PET raw data with substantial noise reduction. Furthermore, we employed the optimization transfer methodology to accelerate 4D expectation-maximization (EM) convergence by nesting the fast image-based estimation of Patlak parameters within each iteration cycle of the slower projection-based estimation of dynamic PET images. The novel gPatlak 4D method was initialized from an optimized set of sPatlak ML-EM iterations to facilitate EM convergence. Initially, realistic simulations were conducted utilizing published (18)F-FDG kinetic parameters coupled with the XCAT phantom. Quantitative analyses illustrated enhanced K i target-to-background ratio (TBR) and especially contrast-to-noise ratio (CNR) performance for the 4D versus the indirect methods and static SUV. Furthermore, considerable convergence acceleration was observed for the nested algorithms involving 10-20 sub-iterations. Moreover, systematic reduction in K i % bias and improved TBR were

  18. Implications of free breathing motion assessed by 4D-computed tomography on the delivered dose in radiotherapy for esophageal cancer.

    PubMed

    Duma, Marciana Nona; Berndt, Johannes; Rondak, Ina-Christine; Devecka, Michal; Wilkens, Jan J; Geinitz, Hans; Combs, Stephanie Elisabeth; Oechsner, Markus

    2015-01-01

    The aim of this study was to assess the effect of breathing motion on the delivered dose in esophageal cancer 3-dimensional (3D)-conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), and volumetric modulated arc therapy (VMAT). We assessed 16 patients with esophageal cancer. All patients underwent 4D-computed tomography (4D-CT) for treatment planning. For each of the analyzed patients, 1 3D-CRT, 1 IMRT, and 1 VMAT (RapidArc-RA) plan were calculated. Each of the 3 initial plans was recalculated on the 4D-CT (for the maximum free inspiration and maximum free expiration) to assess the effect of breathing motion. We assessed the minimum dose (Dmin) and mean dose (Dmean) to the esophagus within the planning target volume, the volume changes of the lungs, the Dmean and the total lung volume receiving at least 40Gy (V40), and the V30, V20, V10, and V5. For the heart we assessed the Dmean and the V25. Over all techniques and all patients the change in Dmean as compared with the planned Dmean (planning CT [PCT]) to the esophagus was 0.48% in maximum free inspiration (CT_insp) and 0.55% in maximum free expiration (CT_exp). The Dmin CT_insp change was 0.86% and CT_exp change was 0.89%. The Dmean change of the lungs (heart) was in CT_insp 1.95% (2.89%) and 3.88% (2.38%) in CT_exp. In all, 4 patients had a clinically relevant change of the dose (≥ 5% Dmean to the heart and the lungs) between inspiration and expiration. These patients had a very cranially or caudally situated tumor. There are no relevant differences in the delivered dose to the regions of interest among the 3 techniques. Breathing motion management could be considered to achieve a better sparing of the lungs or heart in patients with cranially or caudally situated tumors. PMID:26419857

  19. GRAM 88 - 4D GLOBAL REFERENCE ATMOSPHERE MODEL-1988

    NASA Technical Reports Server (NTRS)

    Johnson, D. L.

    1994-01-01

    the Jacchia values. Below 25km the atmospheric parameters are computed by the 4-D worldwide atmospheric model of Spiegler and Fowler (1972). This data set is not included. GRAM-88 incorporates a hydrostatic/gas law check in the 0-30 km altitude range to flag and change any bad data points. Between 5km and 30km, an interpolation scheme is used between the 4-D results and the modified Groves values. The output parameters consist of components for: (1) latitude, longitude, and altitude dependent monthly and annual means, (2) quasi-biennial oscillations (QBO), and (3) random perturbations to partially simulate the variability due to synoptic, diurnal, planetary wave, and gravity wave variations. Quasi-biennial and random variation perturbations are computed from parameters determined by various empirical studies and are added to the monthly mean values. The GRAM-88 program is for batch execution on the IBM 3084. It is written in STANDARD FORTRAN 77 under the MVS/XA operating system. The IBM DISPLA graphics routines are necessary for graphical output. The program was developed in 1988.

  20. Infrared PINEM developed by diffraction in 4D UEM

    PubMed Central

    Liu, Haihua; Baskin, John Spencer; Zewail, Ahmed H.

    2016-01-01

    The development of four-dimensional ultrafast electron microscopy (4D UEM) has enabled not only observations of the ultrafast dynamics of photon–matter interactions at the atomic scale with ultrafast resolution in image, diffraction, and energy space, but photon–electron interactions in the field of nanoplasmonics and nanophotonics also have been captured by the related technique of photon-induced near-field electron microscopy (PINEM) in image and energy space. Here we report a further extension in the ongoing development of PINEM using a focused, nanometer-scale, electron beam in diffraction space for measurements of infrared-light-induced PINEM. The energy resolution in diffraction mode is unprecedented, reaching 0.63 eV under the 200-keV electron beam illumination, and separated peaks of the PINEM electron-energy spectrum induced by infrared light of wavelength 1,038 nm (photon energy 1.2 eV) have been well resolved for the first time, to our knowledge. In a comparison with excitation by green (519-nm) pulses, similar first-order PINEM peak amplitudes were obtained for optical fluence differing by a factor of more than 60 at the interface of copper metal and vacuum. Under high fluence, the nonlinear regime of IR PINEM was observed, and its spatial dependence was studied. In combination with PINEM temporal gating and low-fluence infrared excitation, the PINEM diffraction method paves the way for studies of structural dynamics in reciprocal space and energy space with high temporal resolution. PMID:26848135

  1. Fast interactive exploration of 4D MRI flow data

    NASA Astrophysics Data System (ADS)

    Hennemuth, A.; Friman, O.; Schumann, C.; Bock, J.; Drexl, J.; Huellebrand, M.; Markl, M.; Peitgen, H.-O.

    2011-03-01

    1- or 2-directional MRI blood flow mapping sequences are an integral part of standard MR protocols for diagnosis and therapy control in heart diseases. Recent progress in rapid MRI has made it possible to acquire volumetric, 3-directional cine images in reasonable scan time. In addition to flow and velocity measurements relative to arbitrarily oriented image planes, the analysis of 3-dimensional trajectories enables the visualization of flow patterns, local features of flow trajectories or possible paths into specific regions. The anatomical and functional information allows for advanced hemodynamic analysis in different application areas like stroke risk assessment, congenital and acquired heart disease, aneurysms or abdominal collaterals and cranial blood flow. The complexity of the 4D MRI flow datasets and the flow related image analysis tasks makes the development of fast comprehensive data exploration software for advanced flow analysis a challenging task. Most existing tools address only individual aspects of the analysis pipeline such as pre-processing, quantification or visualization, or are difficult to use for clinicians. The goal of the presented work is to provide a software solution that supports the whole image analysis pipeline and enables data exploration with fast intuitive interaction and visualization methods. The implemented methods facilitate the segmentation and inspection of different vascular systems. Arbitrary 2- or 3-dimensional regions for quantitative analysis and particle tracing can be defined interactively. Synchronized views of animated 3D path lines, 2D velocity or flow overlays and flow curves offer a detailed insight into local hemodynamics. The application of the analysis pipeline is shown for 6 cases from clinical practice, illustrating the usefulness for different clinical questions. Initial user tests show that the software is intuitive to learn and even inexperienced users achieve good results within reasonable processing

  2. 49 CFR 178.53 - Specification 4D welded steel cylinders for aircraft use.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Specification 4D welded steel cylinders for...) SPECIFICATIONS FOR PACKAGINGS Specifications for Cylinders § 178.53 Specification 4D welded steel cylinders for aircraft use. (a) Type, size, and service pressure. A DOT 4D cylinder is a welded steel sphere...

  3. 49 CFR 178.53 - Specification 4D welded steel cylinders for aircraft use.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Specification 4D welded steel cylinders for...) SPECIFICATIONS FOR PACKAGINGS Specifications for Cylinders § 178.53 Specification 4D welded steel cylinders for aircraft use. (a) Type, size, and service pressure. A DOT 4D cylinder is a welded steel sphere...

  4. 49 CFR 178.53 - Specification 4D welded steel cylinders for aircraft use.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Specification 4D welded steel cylinders for...) SPECIFICATIONS FOR PACKAGINGS Specifications for Cylinders § 178.53 Specification 4D welded steel cylinders for aircraft use. (a) Type, size, and service pressure. A DOT 4D cylinder is a welded steel sphere...

  5. 32 CFR 1630.43 - Class 4-D: Minister of religion.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 6 2011-07-01 2011-07-01 false Class 4-D: Minister of religion. 1630.43 Section... CLASSIFICATION RULES § 1630.43 Class 4-D: Minister of religion. In accord with part 1645 of this chapter any registrant shall be placed in Class 4-D who is a: (a) Duly ordained minister of religion; or (b)...

  6. 32 CFR 1630.43 - Class 4-D: Minister of religion.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 6 2014-07-01 2014-07-01 false Class 4-D: Minister of religion. 1630.43 Section... CLASSIFICATION RULES § 1630.43 Class 4-D: Minister of religion. In accord with part 1645 of this chapter any registrant shall be placed in Class 4-D who is a: (a) Duly ordained minister of religion; or (b)...

  7. 32 CFR 1630.43 - Class 4-D: Minister of religion.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 6 2013-07-01 2013-07-01 false Class 4-D: Minister of religion. 1630.43 Section... CLASSIFICATION RULES § 1630.43 Class 4-D: Minister of religion. In accord with part 1645 of this chapter any registrant shall be placed in Class 4-D who is a: (a) Duly ordained minister of religion; or (b)...

  8. 32 CFR 1630.43 - Class 4-D: Minister of religion.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 6 2012-07-01 2012-07-01 false Class 4-D: Minister of religion. 1630.43 Section... CLASSIFICATION RULES § 1630.43 Class 4-D: Minister of religion. In accord with part 1645 of this chapter any registrant shall be placed in Class 4-D who is a: (a) Duly ordained minister of religion; or (b)...

  9. 32 CFR 1630.43 - Class 4-D: Minister of religion.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 6 2010-07-01 2010-07-01 false Class 4-D: Minister of religion. 1630.43 Section... CLASSIFICATION RULES § 1630.43 Class 4-D: Minister of religion. In accord with part 1645 of this chapter any registrant shall be placed in Class 4-D who is a: (a) Duly ordained minister of religion; or (b)...

  10. Acquisition strategies

    SciTech Connect

    Zimmer, M.J.; Lynch, P.W. )

    1993-11-01

    Acquiring projects takes careful planning, research and consideration. Picking the right opportunities and avoiding the pitfalls will lead to a more valuable portfolio. This article describes the steps to take in evaluating an acquisition and what items need to be considered in an evaluation.

  11. 4-D flow magnetic resonance imaging: blood flow quantification compared to 2-D phase-contrast magnetic resonance imaging and Doppler echocardiography

    PubMed Central

    Gabbour, Maya; Schnell, Susanne; Jarvis, Kelly; Robinson, Joshua D.; Markl, Michael

    2015-01-01

    Background Doppler echocardiography (echo) is the reference standard for blood flow velocity analysis, and two-dimensional (2-D) phase-contrast magnetic resonance imaging (MRI) is considered the reference standard for quantitative blood flow assessment. However, both clinical standard-of-care techniques are limited by 2-D acquisitions and single-direction velocity encoding and may make them inadequate to assess the complex three-dimensional hemodynamics seen in congenital heart disease. Four-dimensional flow MRI (4-D flow) enables qualitative and quantitative analysis of complex blood flow in the heart and great arteries. Objectives The objectives of this study are to compare 4-D flow with 2-D phase-contrast MRI for quantification of aortic and pulmonary flow and to evaluate the advantage of 4-D flow-based volumetric flow analysis compared to 2-D phase-contrast MRI and echo for peak velocity assessment in children and young adults. Materials and methods Two-dimensional phase-contrast MRI of the aortic root, main pulmonary artery (MPA), and right and left pulmonary arteries (RPA, LPA) and 4-D flow with volumetric coverage of the aorta and pulmonary arteries were performed in 50 patients (mean age: 13.1±6.4 years). Four-dimensional flow analyses included calculation of net flow and regurgitant fraction with 4-D flow analysis planes similarly positioned to 2-D planes. In addition, 4-D flow volumetric assessment of aortic root/ascending aorta and MPA peak velocities was performed and compared to 2-D phase-contrast MRI and echo. Results Excellent correlation and agreement were found between 2-D phase-contrast MRI and 4-D flow for net flow (r=0.97, P<0.001) and excellent correlation with good agreement was found for regurgitant fraction (r= 0.88, P<0.001) in all vessels. Two-dimensional phase-contrast MRI significantly underestimated aortic (P= 0.032) and MPA (P<0.001) peak velocities compared to echo, while volumetric 4-D flow analysis resulted in higher (aortic: P=0

  12. Mineralization of 2,4-dichlorophenoxyacetic acid (2,4-D) and mixtures of 2,4-D and 2,4,5-trichlorophenoxyacetic acid by Phanerochaete chrysosporium

    SciTech Connect

    Yadav, J.S.; Reddy, C.A. )

    1993-09-01

    2,4-dichloropheonxyacetic Acid (2,4-D) is one of the most commonly used phenoxyalkanoic herbicides for selective control of weeds and for defoliation. Since these toxic chemical are manufactured and used each year in massive quantities, effective handling of their production wastes and the contaminated environment is needed. A number of bacterial general are known to degrade 2,4-D, but no naturally occuring bacterium is know to be capable of mineralizing 2,4,5-trichlorophenoxyacetic acid. Mutual inhibition of degradation has been reported when 2,4-D and 2,4,5-T are presented in a mixture to degrading bacteria. This paper investigates the ability of Pseudomonas chrysosporium to mineralize 2,4-D individually and in combination with 2,4,5-T. Results indicate that P. chrysosporium effectively mineralizes 2,4-D alone as well as in combination with 2,4,5-T. 31 refs., 4 figs., 1 tab.

  13. 4D ground-penetrating radar during a plot scale dye tracer experiment

    NASA Astrophysics Data System (ADS)

    Allroggen, Niklas; van Schaik, N. Loes M. B.; Tronicke, Jens

    2015-07-01

    Flow phenomena in the unsaturated zone are highly variable in time and space. Thus, it is challenging to measure and monitor such processes under field conditions. Here, we present a new setup and interpretation approach for combining a dye tracer experiment with a 4D ground-penetrating radar (GPR) survey. Therefore, we designed a rainfall experiment during which we measured three surface-based 3D GPR surveys using a pair of 500 MHz antennas. Such a survey setup requires accurate acquisition and processing techniques to extract time-lapse information supporting the interpretation of selected cross-sections photographed after excavating the site. Our results reveal patterns of traveltime changes in the measured GPR data, which are associated with soil moisture changes. As distinct horizons are present at our site, such changes can be quantified and transferred into changes in total soil moisture content. Our soil moisture estimates are similar to the amount of infiltrated water, which confirms our experimental approach and makes us confident for further developing this strategy, especially, with respect to improving the temporal and spatial resolution.

  14. CT scan

    MedlinePlus

    ... that slides into the center of the CT scanner. Once you are inside the scanner, the machine's x-ray beam rotates around you. Modern spiral scanners can perform the exam without stopping. A computer ...

  15. A dose error evaluation study for 4D dose calculations

    NASA Astrophysics Data System (ADS)

    Milz, Stefan; Wilkens, Jan J.; Ullrich, Wolfgang

    2014-10-01

    Previous studies have shown that respiration induced motion is not negligible for Stereotactic Body Radiation Therapy. The intrafractional breathing induced motion influences the delivered dose distribution on the underlying patient geometry such as the lung or the abdomen. If a static geometry is used, a planning process for these indications does not represent the entire dynamic process. The quality of a full 4D dose calculation approach depends on the dose coordinate transformation process between deformable geometries. This article provides an evaluation study that introduces an advanced method to verify the quality of numerical dose transformation generated by four different algorithms. The used transformation metric value is based on the deviation of the dose mass histogram (DMH) and the mean dose throughout dose transformation. The study compares the results of four algorithms. In general, two elementary approaches are used: dose mapping and energy transformation. Dose interpolation (DIM) and an advanced concept, so called divergent dose mapping model (dDMM), are used for dose mapping. The algorithms are compared to the basic energy transformation model (bETM) and the energy mass congruent mapping (EMCM). For evaluation 900 small sample regions of interest (ROI) are generated inside an exemplary lung geometry (4DCT). A homogeneous fluence distribution is assumed for dose calculation inside the ROIs. The dose transformations are performed with the four different algorithms. The study investigates the DMH-metric and the mean dose metric for different scenarios (voxel sizes: 8 mm, 4 mm, 2 mm, 1 mm 9 different breathing phases). dDMM achieves the best transformation accuracy in all measured test cases with 3-5% lower errors than the other models. The results of dDMM are reasonable and most efficient in this study, although the model is simple and easy to implement. The EMCM model also achieved suitable results, but the approach requires a more complex

  16. 4D Visualization of Experimental Procedures in Rock Physics

    NASA Astrophysics Data System (ADS)

    Vanorio, T.; di Bonito, C.

    2010-12-01

    Engaging students in laboratory classes in geophysics is becoming more and more difficult. This is primarily because of an ever-widening gap between the less appealing aspects that characterize these courses (e.g., lengthiness of the experimental operations, high student/instrument ratio, limited time associated with lack of previous hands-on experiences, and logistical and safety concerns) and the life style of the 21st century generations (i.e., extensive practice to high-tech tools, high-speed communications and computing, 3D graphics and HD videos). To bridge the gap and enhance the teaching strategy of laboratory courses in geophysics, we have created simulator-training tools for use in preparation for the actual experimental phase. We are using a modeling, animation, and rendering package to create (a) 3D models that accurately reproduce actual scenarios and instruments used for the measurement of rock physics properties and (b) 4D interactive animations that simulate hands-on demonstrations of the experimental procedures. We present here a prototype describing step-by-step the experimental protocol and the principles behind the measurement of rock porosity. The tool reproduces an actual helium porosimeter and makes use of interactive animations, guided text, and a narrative voice guiding the audience through the different phases of the experimental process. Our strategy is to make the most of new technologies while preserving the accuracy of classical laboratory methods and practices. These simulations are not intended to replace traditional lab work; rather they provide students with the opportunity for review and repetition. The primary goal is thus to help students familiarize themselves during their earlier curricula with lab methodologies, thus minimizing apparent hesitation and frustration in later classes. This may also increase the level of interest and involvement of undergraduate students and, in turn, enhance their keenness to pursue their

  17. Experimenting with the GMAO 4D Data Assimilation

    NASA Technical Reports Server (NTRS)

    Todling, R.; El Akkraoui, A.; Errico, R. M.; Guo, J.; Kim, J.; Kliest, D.; Parrish, D. F.; Suarez, M.; Trayanov, A.; Tremolet, Yannick; Whitaker, J.

    2012-01-01

    The Global Modeling and Assimilation Office (GMAO) has been working to promote its prototype four-dimensional variational (4DVAR) system to a version that can be exercised at operationally desirable configurations. Beyond a general circulation model (GeM) and an analysis system, traditional 4DV AR requires availability of tangent linear (TL) and adjoint (AD) models of the corresponding GeM. The GMAO prototype 4DVAR uses the finite-volume-based GEOS GeM and the Grid-point Statistical Interpolation (GSI) system for the first two, and TL and AD models derived ITom an early version of the finite-volume hydrodynamics that is scientifically equivalent to the present GEOS nonlinear GeM but computationally rather outdated. Specifically, the TL and AD models hydrodynamics uses a simple (I-dimensional) latitudinal MPI domain decomposition, which has consequent low scalability and prevents the prototype 4DV AR ITom being used in realistic applications. In the near future, GMAO will be upgrading its operational GEOS GCM (and assimilation system) to use a cubed-sphere-based hydrodynamics. This versions of the dynamics scales to thousands of processes and has led to a decision to re-derive the TL and AD models for this more modern dynamics, thus taking advantage of a two-dimensional MPI decomposition and improved scalability properties. With the aid of the Transformation of Algorithms in FORTRAN (l'AF) automatic adjoint generation tool and some hand-coding, a version of the cubed-sphere-based TL and AD models, with a simplified vertical diffusion scheme, is now available, enabling multiple configurations of standard implementations of 4DV AR in GEOS. Concurrent to this development, collaboration with the National Centers for Environmental Prediction (NCEP) and the Earth System Research Laboratory (ESRL) has allowed GMAO to implement a hybrid-ensemble capability within the GEOS data assimilation system. Both 3Dand 4D-ensemble capabilities are presently available thus allowing

  18. Interactive 4D Visualization of Sediment Transport Models

    NASA Astrophysics Data System (ADS)

    Butkiewicz, T.; Englert, C. M.

    2013-12-01

    Coastal sediment transport models simulate the effects that waves, currents, and tides have on near-shore bathymetry and features such as beaches and barrier islands. Understanding these dynamic processes is integral to the study of coastline stability, beach erosion, and environmental contamination. Furthermore, analyzing the results of these simulations is a critical task in the design, placement, and engineering of coastal structures such as seawalls, jetties, support pilings for wind turbines, etc. Despite the importance of these models, there is a lack of available visualization software that allows users to explore and perform analysis on these datasets in an intuitive and effective manner. Existing visualization interfaces for these datasets often present only one variable at a time, using two dimensional plan or cross-sectional views. These visual restrictions limit the ability to observe the contents in the proper overall context, both in spatial and multi-dimensional terms. To improve upon these limitations, we use 3D rendering and particle system based illustration techniques to show water column/flow data across all depths simultaneously. We can also encode multiple variables across different perceptual channels (color, texture, motion, etc.) to enrich surfaces with multi-dimensional information. Interactive tools are provided, which can be used to explore the dataset and find regions-of-interest for further investigation. Our visualization package provides an intuitive 4D (3D, time-varying) visualization of sediment transport model output. In addition, we are also integrating real world observations with the simulated data to support analysis of the impact from major sediment transport events. In particular, we have been focusing on the effects of Superstorm Sandy on the Redbird Artificial Reef Site, offshore of Delaware Bay. Based on our pre- and post-storm high-resolution sonar surveys, there has significant scour and bedform migration around the

  19. Predicting lower mantle heterogeneity from 4-D Earth models

    NASA Astrophysics Data System (ADS)

    Flament, Nicolas; Williams, Simon; Müller, Dietmar; Gurnis, Michael; Bower, Dan J.

    2016-04-01

    basal layer ˜ 4% denser than ambient mantle. Increasing convective vigour (Ra ≈ 5 x 108) or decreasing the density of the basal layer decreases both the accuracy and sensitivity of the predicted lower mantle structure. References: D. J. Bower, M. Gurnis, N. Flament, Assimilating lithosphere and slab history in 4-D Earth models. Phys. Earth Planet. Inter. 238, 8-22 (2015). V. Lekic, S. Cottaar, A. Dziewonski, B. Romanowicz, Cluster analysis of global lower mantle tomography: A new class of structure and implications for chemical heterogeneity. Earth Planet. Sci. Lett. 357, 68-77 (2012).

  20. Targeted disruption of the heat shock protein 20-phosphodiesterase 4D (PDE4D) interaction protects against pathological cardiac remodelling in a mouse model of hypertrophy.

    PubMed

    Martin, Tamara P; Hortigon-Vinagre, Maria P; Findlay, Jane E; Elliott, Christina; Currie, Susan; Baillie, George S

    2014-01-01

    Phosphorylated heat shock protein 20 (HSP20) is cardioprotective. Using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and a mouse model of pressure overload mediated hypertrophy, we show that peptide disruption of the HSP20-phosphodiesterase 4D (PDE4D) complex results in attenuation of action potential prolongation and protection against adverse cardiac remodelling. The later was evidenced by improved contractility, decreased heart weight to body weight ratio, and reduced interstitial and perivascular fibrosis. This study demonstrates that disruption of the specific HSP20-PDE4D interaction leads to attenuation of pathological cardiac remodelling. PMID:25426411

  1. Principle and applications of dual source CT

    NASA Astrophysics Data System (ADS)

    Flohr, Thomas

    2008-08-01

    Dual source CT (DSCT) has the potential to solve remaining limitations of conventional multi-detector row CT (MDCT)-scanners, such as insufficient temporal resolution for ECG-controlled cardiac imaging. A DSCT is equipped with two X-ray tubes and two corresponding detectors that are mounted onto the rotating gantry with an angular offset of 90°. The key benefit of DSCT for cardiac scanning is improved temporal resolution equivalent to a quarter of the gantry rotation time (83 ms at 0.33 s rotation time). Additionally, both X-ray tubes can be operated at different kV- and mA-settings, enabling the acquisition of dual energy data. The acquisition of dual energy CT data can add functional information to the morphological information based on different X-ray attenuation coefficients that is usually obtained in a CT examination.

  2. Absence of Sema4D improves oligodendrocyte recovery after cerebral ischemia/reperfusion injury in mice.

    PubMed

    Wada, Takenobu; Sawano, Toshinori; Tanaka, Takashi; Furuyama, Tatsuo; Fukumoto, Moe; Yamaguchi, Wataru; Saino, Orie; Takeda, Yuichi; Kogo, Mikihiko; Matsuyama, Tomohiro; Inagaki, Shinobu

    2016-07-01

    Sema4D, originally identified as a negative regulator of axon guidance during development, is involved in various physiological and pathological responses. In this study, we evaluated the effect of Sema4D-deficiency on oligodendrocyte restoration after the cerebral ischemia/reperfusion using direct ligation of the middle cerebral artery followed by reperfusion. In both Sema4D(+/+) wild-type and Sema4D(-/-) null mutant mice, the peri-infarct area showed a decrease in the number of oligodendrocytes at 3 days post-reperfusion. Subsequently, the number of oligodendrocytes was observed to gradually recover in both groups. Sema4D-deficient mice, however, showed an enhanced recovery of oligodendrocytes and an upregulation of oligodendrocyte progenitor cells at days 14 and 28 of reperfusion. Cell proliferation identified by incorporation of bromodeoxyuridine was enhanced in Sema4D(-/-) mice from days 3 to 14 post-reperfusion compared to the Sema4D(+/+) mice. Furthermore, apoptotic cell death of oligodendrocytes was reduced at days 7 post-reperfusion in Sema4D(-/-) mice compared to Sema4D(+/+) mice. These findings indicate that enhanced proliferation of progenitor cells and survival of oligodendrocytes resulted in improved oligodendrocyte recovery in Sema4D(-/-) mice. This may provide a new approach for neurorestorative treatment in patients with stroke, which aims to manipulate endogenous oligodendrogenesis and thereby to promote brain repair after stroke. PMID:26752319

  3. SEMA4D compromises blood-brain barrier, activates microglia, and inhibits remyelination in neurodegenerative disease.

    PubMed

    Smith, Ernest S; Jonason, Alan; Reilly, Christine; Veeraraghavan, Janaki; Fisher, Terrence; Doherty, Michael; Klimatcheva, Ekaterina; Mallow, Crystal; Cornelius, Chad; Leonard, John E; Marchi, Nicola; Janigro, Damir; Argaw, Azeb Tadesse; Pham, Trinh; Seils, Jennifer; Bussler, Holm; Torno, Sebold; Kirk, Renee; Howell, Alan; Evans, Elizabeth E; Paris, Mark; Bowers, William J; John, Gareth; Zauderer, Maurice

    2015-01-01

    Multiple sclerosis (MS) is a chronic neuroinflammatory disease characterized by immune cell infiltration of CNS, blood-brain barrier (BBB) breakdown, localized myelin destruction, and progressive neuronal degeneration. There exists a significant need to identify novel therapeutic targets and strategies that effectively and safely disrupt and even reverse disease pathophysiology. Signaling cascades initiated by semaphorin 4D (SEMA4D) induce glial activation, neuronal process collapse, inhibit migration and differentiation of oligodendrocyte precursor cells (OPCs), and disrupt endothelial tight junctions forming the BBB. To target SEMA4D, we generated a monoclonal antibody that recognizes mouse, rat, monkey and human SEMA4D with high affinity and blocks interaction between SEMA4D and its cognate receptors. In vitro, anti-SEMA4D reverses the inhibitory effects of recombinant SEMA4D on OPC survival and differentiation. In vivo, anti-SEMA4D significantly attenuates experimental autoimmune encephalomyelitis in multiple rodent models by preserving BBB integrity and axonal myelination and can be shown to promote migration of OPC to the site of lesions and improve myelin status following chemically-induced demyelination. Our study underscores SEMA4D as a key factor in CNS disease and supports the further development of antibody-based inhibition of SEMA4D as a novel therapeutic strategy for MS and other neurologic diseases with evidence of demyelination and/or compromise to the neurovascular unit. PMID:25461192

  4. A framework for analytical estimation of patient-specific CT dose

    NASA Astrophysics Data System (ADS)

    Youn, Hanbean; Kim, Jin Woo; Jeon, Hosang; Nam, Jiho; Yun, Seungman; Cho, Min Kook; Kim, Ho Kyung

    2016-03-01

    The authors introduce an algorithm to estimate the spatial dose distributions in computed tomography (CT) images. The algorithm calculates dose distributions due to the primary and scattered photons separately. The algorithm only requires the CT data set that includes the patient CT images and the scanner acquisition parameters. Otherwise the scanner acquisition parameters are extracted from the CT images. Using the developed algorithm, the dose distributions for head and chest phantoms are computed and the results show the excellent agreements with the dose distributions obtained using a commercial Monte Carlo code. The developed algorithm can be applied to a patient-specific CT dose estimation based on the CT data.

  5. A new model of Pde4d deficiency: genetic knock-down of PDE4D enzyme in rats produces an antidepressant phenotype without spatial cognitive effects.

    PubMed

    Schaefer, T L; Braun, A A; Amos-Kroohs, R M; Williams, M T; Ostertag, E; Vorhees, C V

    2012-07-01

    Phosphodiesterases (PDEs) are a superfamily of intracellular second messenger cyclic nucleotide hydrolyzing enzymes composed of 12 families. The Pde4 family has been implicated in depression and cognition, and PDE4 inhibitors have been evaluated as antidepressants and possible cognitive enhancers. Pde4d(-/-) mice show an antidepressant phenotype and learning enhancement on some tests, but not others as do mice treated with PDE4 inhibitors. Here, we report for the first time the behavioral phenotype of a new Pde4d knock-down (KD) rat model of PDE4D deficiency. Consistent with other data on PDE4D deficiency, Pde4d KD rats showed depression resistance in the Porsolt forced swim test and hyperreactivity of the acoustic startle response with no differential response on prepulse inhibition, suggesting no sensorimotor gating defect. Pde4d KD rats also exhibited a small exploratory activity reduction but no difference following habituation, and no enhanced spatial learning or reference memory in the Morris water maze. A selective improvement in route-based learning in the Cincinnati water maze was seen as well as enhanced contextual and cued fear conditioning and a more rapid rate of cued extinction from their higher freezing level that declined to wild-type (WT) levels only after ∼20 extinction trials. The rat model confirms Pde4d's role in depression but not in spatial learning or memory enhancement and shows for the first time higher fear conditioning and altered extinction compared with controls. The new model provides a tool by which to better understand the role of PDE4D in neuropsychiatric disorders and for the development of alternate treatment approaches. PMID:22487514

  6. TH-A-BRF-12: Assessment of 4D-MRI for Robust Motion and Volume Characterization

    SciTech Connect

    Glide-Hurst, C; Kim, J; Wen, N; Chetty, I; Hu, Y; Mutic, S

    2014-06-15

    Purpose: Precise radiation therapy for abdominal lesions is complicated by respiratory motion and poor soft tissue contrast from 4DCT whereas 4DMRI provides superior tissue discrimination. We evaluated a novel 4D-MRI algorithm for MR-SIM motion management. Methods: Respiratory-triggered, T2-weighted single-shot Turbo Spin Echo 4D-MRI was evaluated for open high-field 1.0T MR-SIM. A programmable platform pulled objects on a trolley ∼2 cm superior-inferior (S-I) for “regular” (sinusoidal, (1-cos{sup 2}), 3-5 second periods) and “irregular” breathing patterns (exaggerated (1-cos{sup 2}) and patient curves), while a respiratory waveform was generated via a pressure sensor device. Coronal 4D-MRIs (2–12;10 phases, TE/TR/α = 35−61/6100 ms/90°, voxel=1×1×4 mm{sup 3}) were acquired for 54 unique phantom cases. Abdominal 4D−MRIs were evaluated for 5 healthy volunteers and 1 liver cancer patient (6–10 phases, TE/TR/α = 30−96/4500−6100 ms/90°, voxel=1×1×5–10 mm{sup 3}) on an IRB-approved protocol. Duty cycle, scan time, and excursion were evaluated between phase acquisitions and compared to coronal cine-MRI (∼1 frame/sec). Maximum intensity projections (MIPs) were analyzed. Results: In phantom, average duty cycle was 42.6 ± 11.4% (range: 23.6–69.1%). Regular, periodic breathing (sinusoidal, (1-cos{sup 2})) yielded higher duty cycles than irregular (48.5% and 35.9%, respectively, p<0.001) and fast periods had higher duty cycles than slow (50.4% for 3s and 39.4% for 5s, p<0.001). ∼4-fold acquisition time increase was measured for 10-phase versus 2-phase. MIP renderings revealed that SI object extent was underestimated a maximum of 4% (3mm) and 8% (6mm) for cine and 2-phase 4D-MRI, respectively, with respect to 10-phases. However, this was waveform dependent. A highly irregular breathing volunteer yielded lowest duty cycle (23%) and longest 10-phase scan time (∼14 minutes), although 6-phase acquisition for a liver cancer patient was

  7. Principles of CT and CT technology.

    PubMed

    Goldman, Lee W

    2007-09-01

    This article provides a review of the basic principles of CT within the context of the evolution of CT. Modern CT technology can be understood as a natural progression of improvements and innovations in response to both engineering problems and clinical requirements. Detailed discussions of multislice CT, CT image quality evaluation, and radiation doses in CT will be presented in upcoming articles in this series. PMID:17823453

  8. Neuroimmune semaphorin 4D is necessary for optimal lung allergic inflammation.

    PubMed

    Shanks, K; Nkyimbeng-Takwi, E H; Smith, E; Lipsky, M M; DeTolla, L J; Scott, D W; Keegan, A D; Chapoval, S P

    2013-12-01

    Neuroimmune semaphorin 4D (Sema4D) was found to be expressed and function in the nervous and immune systems. In the immune system, Sema4D is constitutively expressed on T cells and regulates T cell priming. In addition, it displays a stimulatory function on macrophages, DC, NK cells, and neutrophils. As all these cells are deeply involved in asthma pathology, we hypothesized that Sema4D plays a critical non-redundant regulatory role in allergic airway response. To test our hypothesis, we exposed Sema4D(-/-) and WT mice to OVA injections and challenges in the well-defined mouse model of OVA-induced experimental asthma. We observed a significant decrease in eosinophilic airway infiltration in allergen-treated Sema4D(-/-) mice relative to WT mice. This reduced allergic inflammatory response was associated with decreased BAL IL-5, IL-13, TGFβ1, IL-6, and IL-17A levels. In addition, T cell proliferation in OVA₃₂₃₋₃₃₉-restimulated Sema4D(-/-) cell cultures was downregulated. We also found increased Treg numbers in spleens of Sema4D(-/-) mice. However, airway hyperreactivity (AHR) to methacholine challenges was not affected by Sema4D deficiency in either acute or chronic experimental disease setting. Surprisingly, lung DC number and activation were not affected by Sema4D deficiency. These data provide a new insight into Sema4D biology and define Sema4D as an important regulator of Th2-driven lung pathophysiology and as a potential target for a combinatory disease immunotherapy. PMID:23911404

  9. Lumbosacral spine CT

    MedlinePlus

    Spinal CT; CT - lumbosacral spine ... In other cases, a CT of the lumbosacral spine may be done after injecting contrast dye into ... of the body. A CT of the lumbosacral spine can evaluate fractures and changes of the spine, ...

  10. Thoracic CT

    MedlinePlus

    ... table that slides into the center of the scanner. Once you are inside the scanner, the machine's x-ray beam rotates around you. ... than 300 pounds, have your doctor contact the scanner operator before the exam. CT scanners have a ...

  11. Heterozygous mutations in cyclic AMP phosphodiesterase-4D (PDE4D) and protein kinase A (PKA) provide new insights into the molecular pathology of acrodysostosis.

    PubMed

    Kaname, Tadashi; Ki, Chang-Seok; Niikawa, Norio; Baillie, George S; Day, Jonathan P; Yamamura, Ken-Ichi; Ohta, Tohru; Nishimura, Gen; Mastuura, Nobuo; Kim, Ok-Hwa; Sohn, Young Bae; Kim, Hyun Woo; Cho, Sung Yoon; Ko, Ah-Ra; Lee, Jin Young; Kim, Hyun Wook; Ryu, Sung Ho; Rhee, Hwanseok; Yang, Kap-Seok; Joo, Keehyoung; Lee, Jooyoung; Kim, Chi Hwa; Cho, Kwang-Hyun; Kim, Dongsan; Yanagi, Kumiko; Naritomi, Kenji; Yoshiura, Ko-Ichiro; Kondoh, Tatsuro; Nii, Eiji; Tonoki, Hidefumi; Houslay, Miles D; Jin, Dong-Kyu

    2014-11-01

    Acrodysostosis without hormone resistance is a rare skeletal disorder characterized by brachydactyly, nasal hypoplasia, mental retardation and occasionally developmental delay. Recently, loss-of-function mutations in the gene encoding cAMP-hydrolyzing phosphodiesterase-4D (PDE4D) have been reported to cause this rare condition but the pathomechanism has not been fully elucidated. To understand the pathogenetic mechanism of PDE4D mutations, we conducted 3D modeling studies to predict changes in the binding efficacy of cAMP to the catalytic pocket in PDE4D mutants. Our results indicated diminished enzyme activity in the two mutants we analyzed (Gly673Asp and Ile678Thr; based on PDE4D4 residue numbering). Ectopic expression of PDE4D mutants in HEK293 cells demonstrated this reduction in activity, which was identified by increased cAMP levels. However, the cells from an acrodysostosis patient showed low cAMP accumulation, which resulted in a decrease in the phosphorylated cAMP Response Element-Binding Protein (pCREB)/CREB ratio. The reason for this discrepancy was due to a compensatory increase in expression levels of PDE4A and PDE4B isoforms, which accounted for the paradoxical decrease in cAMP levels in the patient cells expressing mutant isoforms with a lowered PDE4D activity. Skeletal radiographs of 10-week-old knockout (KO) rats showed that the distal part of the forelimb was shorter than in wild-type (WT) rats and that all the metacarpals and phalanges were also shorter in KO, as the name acrodysostosis implies. Like the G-protein α-stimulatory subunit and PRKAR1A, PDE4D critically regulates the cAMP signal transduction pathway and influences bone formation in a way that activity-compromising PDE4D mutations can result in skeletal dysplasia. We propose that specific inhibitory PDE4D mutations can lead to the molecular pathology of acrodysostosis without hormone resistance but that the pathological phenotype may well be dependent on an over-compensatory induction

  12. The Relationship Between Digit Ratio (2D:4D) and Sexual Orientation in Men from China.

    PubMed

    Xu, Yin; Zheng, Yong

    2016-04-01

    We examined the relationship between 2D:4D digit ratio and sexual orientation in men from China and analyzed the influences of the components used to assess sexual orientation and the criteria used to classify individuals as homosexual on this relationship. A total of 309 male and 110 female participants took part in a web-based survey. Our results showed that heterosexual men had a significantly lower 2D:4D than heterosexual women and exclusively homosexual men had a significantly higher left 2D:4D than heterosexual men whereas only exclusively homosexual men had a significantly higher right 2D:4D than heterosexual men when sexual orientation was assessed via sexual attraction. The left 2D:4D showed a significant positive correlation with sexual identity, sexual attraction, and sexual behavior, and the right 2D:4D showed a significant positive correlation with sexual attraction. The effect sizes for differences in 2D:4D between homosexual and heterosexual men varied according to criteria used to classify individuals as homosexual and sexual orientation components; the more stringent the criteria (scores closer to the homosexual category), the larger the effect sizes; further, sexual attraction yielded the largest effect size. There were no significant effects of age and latitude on Chinese 2D:4D. This study contributes to the current understanding of the relationship between 2D:4D and male sexual orientation. PMID:25957135

  13. The role of semaphorin 4D as a potential biomarker for antiangiogenic therapy in colorectal cancer

    PubMed Central

    Ding, Xiaojie; Qiu, Lijuan; Zhang, Lijuan; Xi, Juemin; Li, Duo; Huang, Xinwei; Zhao, Yujiao; Wang, Xiaodang; Sun, Qiangming

    2016-01-01

    Background Semaphorin 4D (Sema4D) belongs to the class IV semaphorins, and accumulating evidence has indicated that its elevated level may be one strategy by which tumors evade current anti-angiogenic therapies. The biological roles of Sema4D in colorectal cancer (CRC), however, remain largely undefined. This study was designed to investigate the effects of Sema4D on tumor angiogenesis and growth in CRC, especially in different vascular endothelial growth factor (VEGF) backgrounds. Methods The expression of Sema4D in human CRC was evaluated by immunohistochemical analysis of tumors and their matching normal control tissues. The expression level of Sema4D and VEGF was investigated in different CRC cell lines. To evaluate the contributions of Sema4D to tumor-induced angiogenesis, two CRC cell lines with opposite VEGF backgrounds were infected with lentiviruses expressing Sema4D or Sema4D short hairpin RNA, followed by in vitro migration and in vivo tumor angiogenic assays. Results Immunohistochemical analysis of human CRC revealed high levels of Sema4D in a cell surface pattern. In all, 84.85% of CRC samples analyzed exhibited moderate to strong Sema4D expression. The positive ratios of Sema4D staining for well, moderately, and poorly differentiated cancers were 71.43%, 96.67%, and 77.27%, respectively. Sema4D is highly expressed in five different CRC cell lines, while VEGF expression level varies among these cell lines. HCT-116 showed the lowest VEGF level, while Caco-2 showed the maximum VEGF level. In vitro migration results show that regardless of cell type and VEGF background, Sema4D showed an enhanced in vitro proangiogenic effect to induce the migration of human umbilical vein endothelial cells. Finally, in vivo tumor angiogenic assays demonstrated that Sema4D alone can elicit a significant angiogenic response to promote tumor growth independently of VEGF. Conclusion Targeting Sema4D might serve as a parallel option for antiangiogenic therapy for CRC

  14. 4D MEMRI atlas of neonatal FVB/N mouse brain development.

    PubMed

    Szulc, Kamila U; Lerch, Jason P; Nieman, Brian J; Bartelle, Benjamin B; Friedel, Miriam; Suero-Abreu, Giselle A; Watson, Charles; Joyner, Alexandra L; Turnbull, Daniel H

    2015-09-01

    The widespread use of the mouse as a model system to study brain development has created the need for noninvasive neuroimaging methods that can be applied to early postnatal mice. The goal of this study was to optimize in vivo three- (3D) and four-dimensional (4D) manganese (Mn)-enhanced MRI (MEMRI) approaches for acquiring and analyzing data from the developing mouse brain. The combination of custom, stage-dependent holders and self-gated (motion-correcting) 3D MRI sequences enabled the acquisition of high-resolution (100-μm isotropic), motion artifact-free brain images with a high level of contrast due to Mn-enhancement of numerous brain regions and nuclei. We acquired high-quality longitudinal brain images from two groups of FVB/N strain mice, six mice per group, each mouse imaged on alternate odd or even days (6 3D MEMRI images at each day) covering the developmental stages between postnatal days 1 to 11. The effects of Mn-exposure, anesthesia and MRI were assessed, showing small but significant transient effects on body weight and brain volume, which recovered with time and did not result in significant morphological differences when compared to controls. Metrics derived from deformation-based morphometry (DBM) were used for quantitative analysis of changes in volume and position of a number of brain regions. The cerebellum, a brain region undergoing significant changes in size and patterning at early postnatal stages, was analyzed in detail to demonstrate the spatiotemporal characterization made possible by this new atlas of mouse brain development. These results show that MEMRI is a powerful tool for quantitative analysis of mouse brain development, with great potential for in vivo phenotype analysis in mouse models of neurodevelopmental diseases. PMID:26037053

  15. An innovative detector concept for hybrid 4D-PET/MRI imaging

    NASA Astrophysics Data System (ADS)

    Cerello, P.; Pennazio, F.; Bisogni, M. G.; Marino, N.; Marzocca, C.; Peroni, C.; Wheadon, R.; Del Guerra, A.

    2013-02-01

    The importance of a high-quality hybrid imaging, providing morphological and functional information with only one acquisition session, is widely acknowledged by the scientific community. The historical limitations to the quality of PET images are related to the unsatisfactory measurement of the depth of interaction (DOI) in the crystals and of the time of flight (TOF), that cause a parallax error and an unfavorable signal to background condition in the image reconstruction process, respectively. The 4DMPET project is developing a high performance PET block-detector featuring 4D image reconstruction capabilities. The detector module is based on a fast scintillating continuous crystal coupled on both sides to arrays of Silicon PhotoMultipliers (SiPM). The SiPMs collect the scintillation light and provide the trigger signal, the time and the energy released in the crystal at the pixel level. The photon depth of interaction (DOI) is reconstructed by measuring the cluster size asymmetry on the two faces of the crystal, thus obtaining a comparable spatial resolution in the three coordinates and removing the parallax error. The event position along the line of response can be measured with high precision by means of TOF techniques. We discuss the module design concept and the results of the detailed Monte Carlo detector simulation, which inspire the architectural solutions selected for the layout and the front-end The expected resolution for 3D spatial coordinates of the interaction point in the crystal (1 mm) and the TOF (about 110 ps) would provide a substantial improvement of the image quality. 4DMPET aims at building a prototype block detector demonstrating that the proposed layout meets the expected performance and is suitable for designing a detector focused on a specific application.

  16. 4D seismic monitoring of the miscible CO2 flood of Hall-Gurney Field, Kansas, U.S

    USGS Publications Warehouse

    Raef, A.E.; Miller, R.D.; Byrnes, A.P.; Harrison, W.E.

    2004-01-01

    A cost-effective, highly repeatable, 4D-optimized, single-pattern/patch seismic data-acquisition approach with several 3D data sets was used to evaluate the feasibility of imaging changes associated with the " water alternated with gas" (WAG) stage. By incorporating noninversion-based seismic-attribute analysis, the time and cost of processing and interpreting the data were reduced. A 24-ms-thick EOR-CO 2 injection interval-using an average instantaneous frequency attribute (AIF) was targeted. Changes in amplitude response related to decrease in velocity from pore-fluid replacement within this time interval were found to be lower relative to background values than in AIF analysis. Carefully color-balanced AIF-attribute maps established the overall area affected by the injected EOR-CO2.

  17. A Computational Framework for Quantifying and Optimizing the Performance of Observational Networks in 4D-Var Data Assimilation

    NASA Astrophysics Data System (ADS)

    Cioaca, Alexandru

    A deep scientific understanding of complex physical systems, such as the atmosphere, can be achieved neither by direct measurements nor by numerical simulations alone. Data assimila- tion is a rigorous procedure to fuse information from a priori knowledge of the system state, the physical laws governing the evolution of the system, and real measurements, all with associated error statistics. Data assimilation produces best (a posteriori) estimates of model states and parameter values, and results in considerably improved computer simulations. The acquisition and use of observations in data assimilation raises several important scientific questions related to optimal sensor network design, quantification of data impact, pruning redundant data, and identifying the most beneficial additional observations. These questions originate in operational data assimilation practice, and have started to attract considerable interest in the recent past. This dissertation advances the state of knowledge in four dimensional variational (4D-Var) data assimilation by developing, implementing, and validating a novel computational framework for estimating observation impact and for optimizing sensor networks. The framework builds on the powerful methodologies of second-order adjoint modeling and the 4D-Var sensitivity equations. Efficient computational approaches for quantifying the observation impact include matrix free linear algebra algorithms and low-rank approximations of the sensitivities to observations. The sensor network configuration problem is formulated as a meta-optimization problem. Best values for parameters such as sensor location are obtained by optimizing a performance criterion, subject to the constraint posed by the 4D-Var optimization. Tractable computational solutions to this "optimization-constrained" optimization problem are provided. The results of this work can be directly applied to the deployment of intelligent sensors and adaptive observations, as well as

  18. Rank-sparsity constrained, spectro-temporal reconstruction for retrospectively gated, dynamic CT

    NASA Astrophysics Data System (ADS)

    Clark, D. P.; Lee, C. L.; Kirsch, D. G.; Badea, C. T.

    2015-03-01

    Relative to prospective projection gating, retrospective projection gating for dynamic CT applications allows fast imaging times, minimizing the potential for physiological and anatomic variability. Preclinically, fast imaging is attractive due to the rapid clearance of low molecular weight contrast agents and the rapid heart rate of rodents. Clinically, retrospective gating is relevant for intraoperative C-arm CT. More generally, retrospective sampling provides an opportunity for significant reduction in x-ray dose within the framework of compressive sensing theory and sparsity-constrained iterative reconstruction. Even so, CT reconstruction from projections with random temporal sampling is a very poorly conditioned inverse problem, requiring high fidelity regularization to minimize variability in the reconstructed results. Here, we introduce a highly novel data acquisition and regularization strategy for spectro-temporal (5D) CT reconstruction from retrospectively gated projections. We show that by taking advantage of the rank-sparse structure and separability of the temporal and spectral reconstruction sub-problems, being able to solve each sub-problem independently effectively guarantees that we can solve both problems together. In this paper, we show 4D simulation results (2D + 2 energies + time) using the proposed technique and compare them with two competing techniques— spatio-temporal total variation minimization and prior image constrained compressed sensing. We also show in vivo, 5D (3D + 2 energies + time) myocardial injury data acquired in a mouse, reconstructing 20 data sets (10 phases, 2 energies) and performing material decomposition from data acquired over a single rotation (360°, dose: ~60 mGy).

  19. ECG and Navigator-Free 4D Whole-Heart Coronary MRA for Simultaneous Visualization of Cardiac Anatomy and Function

    PubMed Central

    Pang, Jianing; Sharif, Behzad; Fan, Zhaoyang; Bi, Xiaoming; Arsanjani, Reza; Berman, Daniel S.; Li, Debiao

    2014-01-01

    Purpose To develop a cardiac and respiratory self-gated 4D coronary MRA technique for simultaneous cardiac anatomy and function visualization. Methods A contrast-enhanced, ungated spoiled gradient echo sequence with self-gating (SG) and 3DPR trajectory was used for image acquisition. Data was retrospectively binned into different cardiac and respiratory phases based on information extracted from SG projections using principal component analysis. Each cardiac phase was reconstructed using a respiratory motion-corrected self-calibrating SENSE framework, and those belong to the quiescent period were retrospectively combined for coronary visualization. Healthy volunteer studies were conducted to evaluate the efficacy of the SG method, the accuracy of the left ventricle (LV) function parameters and the quality of coronary artery visualization. Results SG performed reliably for all subjects including one with poor ECG. The LV function parameters showed excellent agreement with those from a conventional cine protocol. For coronary imaging, the proposed method yielded comparable apparent SNR and coronary sharpness and lower apparent CNR on three subjects compared with an ECG and navigator-gated Cartesian protocol and an ECG-gated, respiratory motion-corrected 3DPR protocol. Conclusion A fully self-gated 4D whole-heart imaging technique was developed, potentially allowing cardiac anatomy and function assessment from a single measurement. PMID:25216287

  20. MiR-214 suppressed ovarian cancer and negatively regulated semaphorin 4D.

    PubMed

    Liu, Yang; Zhou, Honglin; Ma, Lan; Hou, Youfang; Pan, Jing; Sun, Chunyi; Yang, Yingying; Zhang, Jie

    2016-06-01

    Ovarian cancer is one of the most common human malignancies in women. MiR-214 and semaphorin 4D (sema 4D) were found to be abhorrently expressed and involved in the progress of several kinds of malignant cancers. This study is aimed to investigate the cellular role of miR-214 and demonstrate that miR-214 negatively regulated sema 4D in ovarian cancer cells. The data showed that miR-214 expression was consistently lower in ovarian cancer tissues and cells than those in the normal controls. Over-expression of miR-214 in ovarian cancer SKOV-3 cells inhibited cell proliferation and induced apoptosis. It was suggested that miR-214 functioned as the tumor suppressor in ovarian cancer. Bioinformatic analysis indicated that miR-214 possibly regulated sema 4D by binding the sema 4D messenger RNA (mRNA) 3'-untranslated region (UTR). Sema 4D mRNA and protein levels were up-regulated in ovarian cancer tissues and SKOV-3 cells. Up-regulation of miR-214 in SKOV-3 cell line suppressed the sema 4D expression in both protein and nucleic acid levels. While, down-regulation of miR-214 in SKOV-3 cells would increase sema 4D protein and nucleic acid expression levels. The effects of miR-214 up- and down-regulation on luciferase activities of wild-type (WT) sema 4D 3'-UTR were completely removed upon introduction of mutation in 3'-UTR of WT sema 4D. Therefore, the data also demonstrated that sema 4D was the direct target of miR-214 and was negatively regulated by miR-214 in ovarian cancer cells. PMID:26718213

  1. Artifacts in CT: recognition and avoidance.

    PubMed

    Barrett, Julia F; Keat, Nicholas

    2004-01-01

    Artifacts can seriously degrade the quality of computed tomographic (CT) images, sometimes to the point of making them diagnostically unusable. To optimize image quality, it is necessary to understand why artifacts occur and how they can be prevented or suppressed. CT artifacts originate from a range of sources. Physics-based artifacts result from the physical processes involved in the acquisition of CT data. Patient-based artifacts are caused by such factors as patient movement or the presence of metallic materials in or on the patient. Scanner-based artifacts result from imperfections in scanner function. Helical and multisection technique artifacts are produced by the image reconstruction process. Design features incorporated into modern CT scanners minimize some types of artifacts, and some can be partially corrected by the scanner software. However, in many instances, careful patient positioning and optimum selection of scanning parameters are the most important factors in avoiding CT artifacts. PMID:15537976

  2. SU-E-J-209: Geometric Distortion at 3T in a Commercial 4D MRI-Compatible Phantom

    SciTech Connect

    Fatemi-Ardekani, A; Wronski, M; Kim, A; Stanisz, G; Sarfehnia, A; Keller, B

    2015-06-15

    Purpose: There are very few commercial 4D phantoms that are marketed as MRI compatible. We are evaluating one such commercial phantom, made to be used with an MRI-Linear accelerator. The focus of this work is to characterize the geometric distortions produced in this phantom at 3T using 3 clinical MR pulse sequences. Methods: The CIRS MRI-Linac Dynamic Phantom (CIRSTM) under investigation in this study consists of a softwaredriven moving tumour volume within a thorax phantom body and enables dose accumulation by placing a dosimeter within the tumour volume. Our initial investigation is to evaluate the phantom in static mode prior to examining its 4D capability. The water-filled thorax phantom was scanned using a wide-bore Philips 3T Achieva MRI scanner employing a Thoracic xl coil and clinical 2D T1W FFE, 2D T1W TSE and 3D T1W TFE pulse sequences. Each of the MR image sets was rigidly fused with a reference CT image of the phantom employing a rigid registration with 6 degrees of freedom. Geometric distortions between the MR and CT image sets were measured in 3 dimensions at selected points along the periphery of the distortion grid embedded within the phantom body (11.5, 7.5 and 3 cm laterally, ant/post and sup/inf of magnetic isocenter respectively). Results: The maximal measured geometric distortions between the MR and reference CT points of interest were 0.9, 1.8 and 1.3 mm in the lateral, anteriorposterior and cranio-caudal directions, respectively. For all 3 spatial dimensions, the maximal distortions occurred for the FFE pulse sequence. Maximal distortions for the 2D FFE, 2D TSE and 3D TFE sequences were 1, 0.7 and 1.8 mm, respectively. Conclusion: Our initial static investigation of this phantom shows minimal geometric distortions at 3T along the periphery of the embedded grid. CIRS has provided us with a phantom at no charge for evaluation at 3 Tesla.

  3. Computer-aided diagnosis of acute ischemic stroke based on cerebral hypoperfusion using 4D CT angiography

    NASA Astrophysics Data System (ADS)

    Charbonnier, Jean-Paul; Smit, Ewoud J.; Viergever, Max A.; Velthuis, Birgitta K.; Vos, Pieter C.

    2013-02-01

    The presence of collateral blood flow is found to be a strong predictor of patient outcome after acute ischemic stroke. Collateral blood flow is defined as an alternative way to provide oxygenated blood to ischemic cerebral tissue. Assessment of collateral blood supply is currently performed by visual inspection of a Computed Tomography Angiogram (CTA) which introduces inter-observer variability and depends on the grading scale. Furthermore, variations in the arterial contrast arrival time may lead to underestimation of collateral blood supply in a CTA which exerts a negative influence on the prediction of patient outcome. In this study, the feasibility of a Computer-aided Diagnosis system is investigated capable of objectively predicting patient outcome. We present a novel automatic method for quantitative assessment of cerebral hypoperfusion in timing-invariant (i.e. delay insensitive) CTA (TI-CTA). The proposed Vessel Density Symmetry algorithm automatically generates descriptive maps based on hemispheric asymmetry of blood vessels. Intensity and symmetry based features are extracted from these descriptive maps and subjected to a best-first-search feature selection. Linear Discriminant Analysis is performed to combine selected features into a likelihood of good patient outcome. Receiver operating characteristic (ROC) analysis is conducted to evaluate the diagnostic performance of the CAD by leave-one- patient-out cross validation. A Positive Predicting Value of 1 was obtained at a sensitivity of 25% with an area under the ROC-curve of 0.86. The results show that the CAD is feasible to objectively predict patient outcome. The presented CAD could make an important contribution to acute ischemic stroke diagnosis and treatment.

  4. SU-E-J-79: Internal Tumor Volume Motion and Volume Size Assessment Using 4D CT Lung Data

    SciTech Connect

    Jurkovic, I; Stathakis, S; Li, Y; Patel, A; Vincent, J; Papanikolaou, N; Mavroidis, P

    2014-06-01

    Purpose: To assess internal tumor volume change through breathing cycle and associated tumor motion using the 4DCT data. Methods: Respiration induced volume change through breathing cycle and associated motion was analyzed for nine patients that were scanned during the different respiratory phases. The examined datasets were the maximum and average intensity projections (MIP and AIP) and the 10 phases of the respiratory cycle. The internal target volume (ITV) was delineated on each of the phases and the planning target volume (PTV) was then created by adding setup margins to the ITV. Tumor motion through the phases was assessed using the acquired 4DCT dataset, which was then used to determine if the margins used for the ITV creation successfully encompassed the tumor in three dimensions. Results: Results showed that GTV motion along the superior inferior axes was the largest in all the cases independent of the tumor location and/or size or the use of abdomen compression. The extent of the tumor motion was found to be connected with the size of the GTV. The smallest GTVs exhibited largest motion vector independent of the tumor location. The motion vector size varied through the phases depending on the tumor size and location and it was smallest for phases 20 and 30. The smaller the volume of the delineated GTV, the greater its volume difference through the different respiratory phases was. The average GTV volume change was largest for the phases 60 and 70. Conclusion: Even if GTV is delineated using both AIP and MIP datasets, its motion extent will exceed the used margins especially for the very small GTV volumes. When the GTV size is less than 10 cc it is recommended to use fusion of the GTVs through all the phases to create the planning ITV.

  5. Curves of AW(k)-type in 4D Galilean space

    NASA Astrophysics Data System (ADS)

    Külahci, Mihriban

    2016-04-01

    In this paper, we investigate curves of AW(k)-type (1 ≤ k ≤ 3) in 4D Galilean space and we give curvature conditions of these kind of curves. Also, we study weak AW(2)-type curves. Furthermore, we express mannheim curves of AW(k)-type in 4D Galilean space.

  6. Elite collegiate tennis athletes have lower 2D: 4D ratios than those of nonathlete controls.

    PubMed

    Hsu, Cheng-Chen; Su, Borcherng; Kan, Nai-Wen; Lai, Su-Ling; Fong, Tsorng-Harn; Chi, Chung-Pu; Chang, Ching-Chyuan; Hsu, Mei-Chich

    2015-03-01

    The ratio of the length of the second finger (index finger) to the fourth finger (ring finger) (2D:4D ratio) is a putative marker for prenatal hormones. Physiological research has suggested a low 2D:4D ratio correlates with high athletic ability. Athletes of specific sports (e.g., American football) have lower 2D:4D ratios than those of nonathletes, whereas athletes of some sports (e.g., rowing, gymnastics, and soccer) do not. This study investigated the 2D:4D ratios among collegiate tennis athletes, elite collegiate tennis athletes, and nonelite collegiate tennis athletes and compared them with nonathletes of both sexes. The participants included 43 elite collegiate tennis athletes (Level I intercollegiate athletes in Taiwan; 27 males and 16 females), 107 nonelite collegiate tennis athletes (Level II athletes; 55 males and 52 females), and 166 nonathlete college students (80 males and 86 females).