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https://www.readbyqxmd.com/read/28079527/binary-moving-blocker-based-scatter-correction-in-cone-beam-computed-tomography-with-width-truncated-projections-proof-of-concept
#1
Ho Lee, Benjamin Fahimian, Lei Xing
This paper proposes a binary moving-blocker (BMB)-based technique for scatter correction in cone-beam computed tomography (CBCT). In concept, a beam blocker consisting of lead strips, mounted in front of the x-ray tube, moves rapidly in and out of the beam during a single gantry rotation. The projections are acquired in alternating phases of blocked and unblocked cone beams, where the blocked phase results in a stripe pattern in the width direction. To derive the scatter map from the blocked projections, one-dimensional B-Spline interpolation/extrapolation is applied by using the detected information in the shaded regions...
January 12, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28048892/su-f-j-116-clinical-experience-based-verification-and-improvement-of-a-4dct-program
#2
P Fogg, M West, T Aland
PURPOSE: To demonstrate the role of continuous improvement fulfilled by the Medical Physicist in clinical 4DCT and CBCT scanning. METHODS: Lung (SABR and Standard) patients' 4D respiratory motion and image data were reviewed over a 3, 6 and 12 month period following commissioning testing. By identifying trends of clinically relevant parameters and respiratory motions, variables were tested with a programmable motion phantom and assessed. Patient traces were imported to a motion phantom and 4DCT and CBCT imaging were performed...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048885/mo-d-brb-03-quality-assurance-of-sbrt
#3
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/28048870/su-f-j-81-evaluation-of-automated-deformable-registration-between-planning-computed-tomography-ct-and-daily-cone-beam-ct-images-over-the-course-of-prostate-cancer-radiotherapy
#4
J Matney, J Hammers, O Kaidar-Person, A Wang, R Chen, S Das, L Marks, P Mavroidis
PURPOSE: To compute daily dose delivered during radiotherapy, deformable registration needs to be relatively fast, automated, and accurate. The aim of this study was to evaluate the performance of commercial deformable registration software for deforming between two modalities: planning computed tomography (pCT) images acquired for treatment planning and cone beam (CB) CT images acquired prior to each fraction of prostate cancer radiotherapy. METHODS: A workflow was designed using MIM Softwareâ„¢ that aligned and deformed pCT into daily CBCT images in two steps: (1) rigid shifts applied after daily CBCT imaging to align patient anatomy to the pCT and (2) normalized intensity-based deformable registration to account for interfractional anatomical variations...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048791/su-f-j-48-effect-of-scan-length-on-magnitude-of-imaging-dose-in-kv-cbct
#5
S Deshpande, D Dhote, S Naidu, A Sutar, V Kannan
PURPOSE: To study effect of scan length on magnitude of imaging dose deposition in Varian kV CBCT for head & neck and pelvis CBCT. METHODS: To study effect of scan length we measured imaging dose at depth of 8 cm for head and neck Cone Beam Computed Tomography (CBCT) acquisition (X ray beam energy is used 100kV and 200 degree of gantry rotation) and at 16 cm depth for pelvis CBCT acquisition (X ray beam energy used is 125 kV and 360 degree of gantry rotation) in specially designed phantom...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048768/su-f-i-03-correction-of-intra-fractional-set-up-errors-and-target-coverage-based-on-cone-beam-computed-tomography-for-cervical-cancer-patients
#6
J Y Zhang, D L Hong
PURPOSE: The purpose of this study is to investigate the patient set-up error and interfraction target coverage in cervical cancer using image-guided adaptive radiotherapy (IGART) with cone-beam computed tomography (CBCT). METHODS: Twenty cervical cancer patients undergoing intensity modulated radiotherapy (IMRT) were randomly selected. All patients were matched to the isocenter using laser with the skin markers. Three dimensional CBCT projections were acquired by the Varian Truebeam treatment system...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048690/su-f-j-22-lung-volumevariability-assessed-by-bh-cbct-in-3d-surface-image-guided-deep-inspirationbreath-hold-dibh-radiotherapy-for-left-sided-breast-cancer
#7
A Gutierrez, D Stanley, N Papanikolaou, R Crownover
PURPOSE: With the increasing use of DIBH techniques for left-sided breast cancer, 3D surface-image guided DIBH techniques have improved patient setup and facilitated DIBH radiation delivery. However, quantification of the daily separation between the heart and left breast still presents a challenge. One method of assuring separation is to ensure consistent left lung filling. With this in mind, the aim of this study is to retrospectively quantify left lung volume from weekly breath hold-CBCTs (bh-CBCT) of left-sided breast patients treated using a 3D surface imaging system...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048660/tu-b-201-01-an-overview-of-tg-180
#8
G Ding
: Radiotherapy is in the era of image guided radiation therapy (IGRT) in which imaging procedures are routinely performed for patient positioning, and target localization. The additional imaging dose delivered may increase risk to the patient and therefore needs to be managed. This lecture provides an overview of the AAPM TG-180 which is charged with: providing an overview on imaging dose including megavoltage electronic portal imaging (MV EPI), kilovoltage digital radiography (kV DR), Tomotherapy MV-CT, megavoltage cone-beam CT (MV-CBCT) and kilovoltage cone-beam CT (kV-CBCT) as well as providing general guidelines for commissioning and managing imaging dose calculations...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048589/su-f-t-320-assessing-placement-error-of-optically-stimulated-luminescent-in-vivo-dosimeters-using-cone-beam-computed-tomography
#9
A Riegel, M Tariq, C Gomez, E Klein
PURPOSE: Optically-stimulated luminescent dosimeters (OSLDs) are increasingly utilized for in vivo dosimetry of complex radiation delivery techniques such as intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT). Evaluation of clinical uncertainties such as placement error has not been performed. This work retrospectively investigates the magnitude of placement error using conebeam computed tomography (CBCT) and its effect on measured/planned dose agreement...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048581/su-c-204-06-monte-carlo-dose-calculation-for-kilovoltage-x-ray-psoralen-activated-cancer-therapy-x-pact-preliminary-results
#10
S Mein, R Gunasingha, M Nolan, M Oldham, J Adamson
PURPOSE: X-PACT is an experimental cancer therapy where kV x-rays are used to photo-activate anti-cancer therapeutics through phosphor intermediaries (phosphors that absorb x-rays and re-radiate as UV light). Clinical trials in pet dogs are currently underway (NC State College of Veterinary Medicine) and an essential component is the ability to model the kV dose in these dogs. Here we report the commissioning and characterization of a Monte Carlo (MC) treatment planning simulation tool to calculate X-PACT radiation doses in canine trials...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048560/tu-h-campus-jep1-04-deformable-image-registration-performances-in-pelvis-patients-impact-of-cbct-image-quality
#11
M Fusella, G Loi, C Fiandra, E Lanzi
PURPOSE: To investigate the accuracy and robustness, against image noise and artifacts (typical of CBCT images), of a commercial algorithm for deformable image registration (DIR), to propagate regions of interest (ROIs) in computational phantoms based on real prostate patient images. METHODS: The Anaconda DIR algorithm, implemented in RayStation was tested. Two specific Deformation Vector Fields (DVFs) were applied to the reference data set (CTref) using the ImSimQA software, obtaining two deformed CTs...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048467/su-g-jep2-08-image-guided-radiation-therapy-using-synthetic-cts-in-brain-cancer
#12
R G Price, J Kim, W Zheng, I J Chetty, C Glide-Hurst
PURPOSE: Synthetic-CTs(synCTs) are essential for MR-only treatment planning. However, the performance of synCT for IGRT must be carefully assessed. This work evaluated the accuracy of synCT and synCT-generated DRRs and determined their performance for IGRT in brain cancer radiation therapy. METHODS: MR-SIM and CT-SIM images were acquired of a novel anthropomorphic phantom and a cohort of 12 patients. SynCTs were generated by combining an ultra-short echo time (UTE) sequence with other MRI datasets using voxel-based weighted summation...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048410/su-f-t-682-in-vivo-simulation-of-the-relative-biological-effectiveness-in-proton-therapy-using-a-monte-carlo-method
#13
H Oesten, S Loeck, S Helmbrecht, F Tillner, P Wohlfahrt, J Schuemann, A Luehr
PURPOSE: In proton therapy, the relative biological effectiveness (RBE) - compared with conventional photon therapy - is routinely set to 1.1. However, experimental in vitro studies indicate evidence for the variability of the RBE. To clarify the impact on patient treatment, investigation of the RBE in a preclinical case study should be performed. METHODS: The Monte Carlo software TOPAS was used to simulate the radiation field of an irradiation setup at the experimental beamline of the proton therapy facility (OncoRay) in Dresden, Germany...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048292/su-g-jep4-06-evaluation-of-interfractional-and-intrafractional-tumor-motion-in-stereotactic-liver-radiotherapy-based-on-four-dimensional-cone-beam-computed-tomography-using-fiducial-markers
#14
Y Shimohigashi, F Araki, R Toya, M Maruyama, Y Nakaguchi
PURPOSE: The purpose of this study was to evaluate the interfractional and intrafractional motion of liver tumors in stereotactic body radiation therapy (SBRT), based on four-dimensional cone-beam computed tomography using fiducial markers. (4D-CBCT). METHODS: Seven patients with liver tumors were treated by SBRT with abdominal compression (AC) in five fractions with image guidance based on 4D-CBCT. The 4D-CBCT studies were performed to determine the individualized internal margin for the planning simulation...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048270/su-g-jep3-06-lower-kv-image-dose-are-expected-from-a-limited-angle-intra-fractional-verification-live-system-for-sbrt-treatments
#15
G Ding, F Yin, L Ren
PURPOSE: In order to track the tumor movement for patient positioning verification during arc treatment delivery or in between 3D/IMRT beams for stereotactic body radiation therapy (SBRT), the limited-angle kV projections acquisition simultaneously during arc treatment delivery or in-between static treatment beams as the gantry moves to the next beam angle was proposed. The purpose of this study is to estimate additional imaging dose resulting from multiple tomosynthesis acquisitions in-between static treatment beams and to compare with that of a conventional kV-CBCT acquisition...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048240/su-f-j-117-impact-of-motion-artifacts-on-image-quality-and-accuracy-of-tumor-motion-reconstruction-in-4d-ct-on-rails-and-mv-cbct-scans-a-phantom-study
#16
T Lin, C Ma
PURPOSE: To compare and quantify respiratory motion artifacts in images from free breathing 4D-CT-on-Rails(CTOR) and those from MV-Cone-beam-CT(MVCB) and facilitate respiratory motion guided radiation therapy. METHODS: 4D-CTOR: Siemens Somatom CT-on-Rails system with Anzai belt loaded with pressure sensor load cells. 4D scans were performed in helical mode, pitch 0.1, gantry rotation time 0.5s, 1.5mm slice thickness, 120kVp, 400 mAs. Normal and fast breathing (>12rpm) scanning protocols were investigated...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048202/we-h-brc-02-failure-mode-and-effect-analysis-of-liver-stereotactic-body-radiotherapy
#17
I Rusu, T Thomas, J Roeske, J Price, C Perino, I Mescioglu, M Surucu
PURPOSE: To identify areas of improvement in our liver stereotactic body radiation therapy (SBRT) program, using failure mode and effect analysis (FMEA). METHODS: A multidisciplinary group consisting of one physician, three physicists, one dosimetrist and two therapists was formed. A process map covering 10 major stages of the liver SBRT program from the initial diagnosis to post treatment follow-up was generated. A total of 102 failure modes, together with their causes and effects, were identified...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048176/su-g-bra-10-marker-free-lung-tumor-motion-tracking-by-an-active-contour-model-on-cone-beam-ct-projections-for-stereotactic-body-radiation-therapy-of-lung-cancer
#18
M Chao, J Wei, Y Yuan, Y Lo
PURPOSE: To develop a novel strategy to extract the lung tumor motion from cone beam CT (CBCT) projections by an active contour model with interpolated respiration learned from diaphragm motion. METHODS: Tumor tracking on CBCT projections was accomplished with the templates derived from planning CT (pCT). There are three major steps in the proposed algorithm: 1) The pCT was modified to form two CT sets: a tumor removed pCT and a tumor only pCT, the respective digitally reconstructed radiographs DRRtr and DRRto following the same geometry of the CBCT projections were generated correspondingly...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048156/su-f-j-20-commissioning-and-acceptance-testing-of-the-c-rad-catalysthd-surface-imaging-system
#19
D Stanley, K Rasmussen, N Kirby, N Papanikolaou, A Gutierrez
INTRODUCTION: With the increasing use of surface-based, nonionizing image-guided radiotherapy (IGRT) systems, a comprehensive set of clinical acceptance and commissioning procedures are needed to ensure correct functionality and proper clinical integration. Although TG-147 provides a specific set of parameters, measurement methodologies have yet to be described. The aim of this study was to provide a comprehensive overview of the commissioning and acceptance analysis performed for the C-Rad CatalystHD imaging system...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048128/mo-d-brb-00-sbrt-workflow-overview
#20
Lei Xing
: 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
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