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4D CT

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https://www.readbyqxmd.com/read/28079267/estimating-4d-cbct-from-prior-information-and-extremely-limited-angle-projections-using-structural-pca-and-weighted-free-form-deformation-for-lung-radiotherapy
#1
Wendy Harris, You Zhang, Fang-Fang Yin, Lei Ren
PURPOSE: To investigate the feasibility of using structural-based principal component analysis (PCA) motion-modeling and weighted free-form deformation to estimate on-board 4D-CBCT using prior information and extremely limited angle projections for potential 4D target verification of lung radiotherapy. METHODS: A technique for lung 4D-CBCT reconstruction has been previously developed using a deformation field map (DFM)-based strategy. In the previous method, each phase of the 4D-CBCT was generated by deforming a prior CT volume...
January 12, 2017: Medical Physics
https://www.readbyqxmd.com/read/28074019/point-organ-radiation-dose-in-abdominal-ct-effect-of-patient-off-centering-in-an-experimental-human-cadaver-study
#2
Ranish Deedar Ali Khawaja, Sarabjeet Singh, Atul Padole, Alexi Otrakji, Diego Lira, Da Zhang, Bob Liu, Andrew Primak, George Xu, Mannudeep K Kalra
To determine the effect of patient off-centering on point organ radiation dose measurements in a human cadaver scanned with routine abdominal CT protocol. A human cadaver (88 years, body-mass-index 20 kg/m(2)) was scanned with routine abdominal CT protocol on 128-slice dual source MDCT (Definition Flash, Siemens). A total of 18 scans were performed using two scan protocols (a) 120 kV-200 mAs fixed-mA (CTDIvol 14 mGy) (b) 120 kV-125 ref mAs (7 mGy) with automatic exposure control (AEC, CareDose 4D) at three different positions (a) gantry isocenter, (b) upward off-centering and (c) downward off-centering...
January 10, 2017: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/28073579/robustness-of-4d-optimized-scanned-carbon-ion-beam-therapy-against-interfractional-changes-in-lung-cancer
#3
Christian Graeff
BACKGROUND AND PURPOSE: Moving targets could be conformally treated with actively scanned carbon ion beams using 4D-optimization. As this heavily exploits 4D-CTs, an important question is whether the conformity also upholds in the context of interfractional changes, i.e. variable positioning, anatomy and breathing patterns. MATERIALS AND METHODS: In 4 lung cancer patients, 6 weekly 4D-CTs were available. 4D-CTs and their phases were non-rigidly registered to propagate contours and 4D-doses...
January 7, 2017: Radiotherapy and Oncology: Journal of the European Society for Therapeutic Radiology and Oncology
https://www.readbyqxmd.com/read/28073377/magnitude-and-influencing-factors-of-respiration-induced-liver-motion-during-abdominal-compression-in-patients-with-intrahepatic-tumors
#4
Yong Hu, Yong-Kang Zhou, Yi-Xing Chen, Zhao-Chong Zeng
PURPOSE: The purpose of this study was to use 4-dimensional-computed tomography (4D-CT) to evaluate respiration-induced liver motion magnitude and influencing factors in patients with intrahepatic tumors undergoing abdominal compression. METHODS: From January 2012 to April 2016, 99 patients with intrahepatic tumors were included in this study. They all underwent 4D-CT to assess respiratory liver motion. This was performed during abdominal compression in 53 patients and during free-breathing (no abdominal compression) in 46 patients...
January 10, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28052050/planning-four-dimensional-intensity-modulated-arc-therapy-for-tumor-tracking-with-a-multileaf-collimator
#5
Ying Niu, Gregory Betzel, Xiaocheng Yang, Minzhi Gui, William Parke, Byong Yi, Cedric Yu
This study introduces a practical four-dimensional (4D) planning scheme of IMAT using 4D computed tomography (4D CT) for planning tumor tracking with dynamic multileaf beam collimation. We assume that patients can breathe regularly, i.e., the same way as during 4D CT with an unchanged period and amplitude, and that the start of 4D-IMAT delivery can be synchronized with a designated respiratory phase. Each control point of the IMAT-delivery process can be associated with an image set of 4D CT at a specified respiratory phase...
January 4, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28048927/mo-fg-bra-05-dosimetric-and-radiobiological-validation-of-respiratory-gating-in-conventional-and-hypofractionated-radiotherapy-of-the-lung-effect-of-dose-dose-rate-gating-window-and-breathing-pattern
#6
L Cervino, D Soultan, N Pettersson, A Yock, M Cornell, J Aguilera, J Murphy, B Gill, S Advani, V Moiseenko
PURPOSE: to evaluate the dosimetric and radiobiological consequences from having different gating windows, dose rates, and breathing patterns in gated VMAT lung radiotherapy. METHODS: A novel 3D-printed moving phantom with central high and peripheral low tracer uptake regions was 4D FDG-PET/CT-scanned using ideal, patient-specific regular, and irregular breathing patterns. A scan of the stationary phantom was obtained as a reference. Target volumes corresponding to different uptake regions were delineated...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048919/su-g-jep3-05-geometry-based-transperineal-ultrasound-probe-positioning-for-image-guided-radiotherapy
#7
S Camps, F Verhaegen, P de With, D Fontanarosa
PURPOSE: The use of ultrasound (US) imaging in radiotherapy is not widespread, primarily due to the need for skilled operators performing the scans. Automation of probe positioning has the potential to remove this need and minimize operator dependence. We introduce an algorithm for obtaining a US probe position that allows good anatomical structure visualization based on clinical requirements. The first application is on 4D transperineal US images of prostate cancer patients. METHODS: The algorithm calculates the probe position and orientation using anatomical information provided by a reference CT scan, always available in radiotherapy workflows...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048885/mo-d-brb-03-quality-assurance-of-sbrt
#8
J Roper
: Increased use of SBRT and hypofractionation in radiation oncology practice has posted a number of challenges to medical physicist, ranging from planning, image-guided patient setup and on-treatment monitoring, to quality assurance (QA) and dose delivery. This symposium is designed to provide current knowledge necessary for the safe and efficient implementation of SBRT in various linac platforms, including the emerging digital linacs equipped with high dose rate FFF beams. Issues related to 4D CT, PET and MRI simulations, 3D/4D CBCT guided patient setup, real-time image guidance during SBRT dose delivery using gated/un-gated VMAT/IMRT, and technical advancements in QA of SBRT (in particular, strategies dealing with high dose rate FFF beams) will be addressed...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048878/th-cd-209-08-quantification-of-the-interplay-effect-in-proton-pencil-beam-scanning-treatment-of-lung
#9
M Kang, S Huang, T Solberg, R Mayer, A Thomas, B Teo, J McDonough, C Simone, L Lin
PURPOSE: To quantify the dose degradation caused by the interplay effect based on a beam specific motion analysis in proton pencil beam scanning (PBS) treatment of lung tumors METHODS: PBS plans were optimized on average CT using a beam-specific PTV method for 10 consecutive patients with locally advanced non-small-cell-lung-cancer (NSCLC) treated with proton therapy to 6660/180 cGy. End inhalation (CT0) and end exhalation (CT50) were selected as the two extreme scenarios to acquire the relative stopping power ratio difference (Δrsp) for a respiration cycle...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048865/mo-de-207a-08-four-dimensional-cone-beam-ct-iterative-reconstruction-with-time-ordered-chain-graph-model-for-non-periodic-organ-motion-and-deformation
#10
M Nakano, A Haga, J Kotoku, T Magome, Y Masutani, S Hanaoka, K Nakagawa
PURPOSE: The purpose of this study is to propose a new concept of four-dimensional (4D) cone-beam CT (CBCT) reconstruction for non-periodic organ motion using the Time-ordered Chain Graph Model (TCGM), and to compare the reconstructed results with the previously proposed methods, the total variation-based compressed sensing (TVCS) and prior-image constrained compressed sensing (PICCS). METHODS: CBCT reconstruction method introduced in this study consisted of maximum a posteriori (MAP) iterative reconstruction combined with a regularization term derived from a concept of TCGM, which includes a constraint coming from the images of neighbouring time-phases...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048834/th-ef-bra-03-assessment-of-data-driven-respiratory-motion-compensation-methods-for-4d-cbct-image-registration-and-reconstruction-using-clinical-datasets
#11
M J Riblett, E Weiss, G E Christensen, G D Hugo
PURPOSE: To evaluate the performance of a 4D-CBCT registration and reconstruction method that corrects for respiratory motion and enhances image quality under clinically relevant conditions. METHODS: Building on previous work, which tested feasibility of a motion-compensation workflow using image datasets superior to clinical acquisitions, this study assesses workflow performance under clinical conditions in terms of image quality improvement. Evaluated workflows utilized a combination of groupwise deformable image registration (DIR) and image reconstruction...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048777/mo-e-brb-00-panel-discussion-sbrt-srs-case-studies-lung
#12
Stanley Benedict
: In this interactive session, lung SBRT patient cases will be presented to highlight real-world considerations for ensuring safe and accurate treatment delivery. An expert panel of speakers will discuss challenges specific to lung SBRT including patient selection, patient immobilization techniques, 4D CT simulation and respiratory motion management, target delineation for treatment planning, online treatment alignment, and established prescription regimens and OAR dose limits. Practical examples of cases, including the patient flow thought the clinical process are presented and audience participation will be encouraged...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048764/tu-d-202-00-rest-in-peace-itv
#13
Marcel van Herk
: Respiratory motion has long been recognized as an important factor affecting the precision of radiotherapy. After the introduction of the 4D CT to visualize the respiratory motion in 3D, the internal target volume (ITV) has been widely adopted as simple method to take the motion into account in treatment planning and delivery. The ITV is generated as the union of the CTVs as the patient goes through the respiratory cycle. Many issues have been identified with the ITV. In this session three alternatives for the ITV will be discussed: 1) An alternative motion-inclusive approach with better imaging and smaller margins, called mid-position CT...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048757/mo-e-brb-01-panel-member
#14
S Benedict
: In this interactive session, lung SBRT patient cases will be presented to highlight real-world considerations for ensuring safe and accurate treatment delivery. An expert panel of speakers will discuss challenges specific to lung SBRT including patient selection, patient immobilization techniques, 4D CT simulation and respiratory motion management, target delineation for treatment planning, online treatment alignment, and established prescription regimens and OAR dose limits. Practical examples of cases, including the patient flow thought the clinical process are presented and audience participation will be encouraged...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048745/tu-d-brc-01-novel-applications-for-current-epid-technology
#15
J Rottmann
There has been increased deployment of gantry-mounted linacs with onboard kilovoltage x-ray imagers. Despite this trend, most clinics still employ beam's-eye-view (BEV) imaging using flat panel electronic portal imaging devices (EPIDs) as a highly useful means of verifying geometric localization pre- and post-delivery. In recent years, there has been increased interest in the use of EPIDs for a variety of clinical and investigational applications ranging from megavoltage cone-beam CT, in vivo dosimetry, patient-specific QA to real-time target localization for dynamic MLC-based tumor tracking...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048720/tu-ab-202-05-gpu-based-4d-deformable-image-registration-using-adaptive-tetrahedral-mesh-modeling
#16
Z Zhong, L Zhuang, X Gu, J Wang, H Chen, X Zhen
PURPOSE: Deformable image registration (DIR) has been employed today as an automated and effective segmentation method to transfer tumor or organ contours from the planning image to daily images, instead of manual segmentation. However, the computational time and accuracy of current DIR approaches are still insufficient for online adaptive radiation therapy (ART), which requires real-time and high-quality image segmentation, especially in a large datasets of 4D-CT images. The objective of this work is to propose a new DIR algorithm, with fast computational speed and high accuracy, by using adaptive feature-based tetrahedral meshing and GPU-based parallelization...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048700/tu-d-bra-00-treatment-planning-system-commissioning-and-qa
#17
Greg Salomons
INTRODUCTION: Treatment planning systems (TPS) are a cornerstone of modern radiation therapy. Errors in their commissioning or use can have a devastating impact on many patients. To support safe and high quality care, medical physicists must conduct efficient and proper commissioning, good clinical integration, and ongoing quality assurance (QA) of the TPS. AAPM Task Group 53 and related publications have served as seminal benchmarks for TPS commissioning and QA over the past two decades...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048668/tu-ab-202-01-multi-institutional-validation-study-of-commercially-available-deformable-image-registration-software-for-thoracic-images
#18
N Kadoya, Y Nakajima, M Saito, Y Miyabe, M Kurooka, S Kito, M Sasaki, Y Fujita, K Arai, K Tani, M Yagi, A Wakita, N Tohyama, K Jingu
PURPOSE: The purpose of this study was to assess the accuracy of commercially available deformable image registration (DIR) software for thoracic images on multi-institution. Furthermore, we determined the variation in the DIR accuracy among institutions due to different DIR algorithms and DIR procedures. METHODS: Thoracic four-dimensional (4D) CT images of ten patients with esophagus or lung cancer were used. Datasets for these patients were provided by DIR-lab (dir-lab...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048664/tu-d-202-03-gating-is-the-best-itv-killer
#19
D Low
: Respiratory motion has long been recognized as an important factor affecting the precision of radiotherapy. After the introduction of the 4D CT to visualize the respiratory motion in 3D, the internal target volume (ITV) has been widely adopted as simple method to take the motion into account in treatment planning and delivery. The ITV is generated as the union of the CTVs as the patient goes through the respiratory cycle. Many issues have been identified with the ITV. In this session three alternatives for the ITV will be discussed: 1) An alternative motion-inclusive approach with better imaging and smaller margins, called mid-position CT...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048579/su-f-t-389-validation-in-4d-dosimetry-using-dynamic-phantom
#20
C Lin, T Huang, C Lin, H Nien, P Tu, L Lui, C Wu
PURPOSE: Tumor motion due to respiration causes the uncertainties during the radiotherapy. This study aims to find the differences between planning dose by treatment planning and the received dose using dynamic phantom. METHODS: Respiratory motion was simulated by the DYNAMIC THORAX PHANTOM (Model 008A). 4D-CT scans and maximum intensity projection (MIP) images for GTV were acquired for analysis. The amplitude of craniocaudal tumor motion including 2mm, 5mm, 10mm and 20mm with 3cm2 tumor size were performed in this study...
June 2016: Medical Physics
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