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Cone beam CT

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https://www.readbyqxmd.com/read/28086901/gpu-accelerated-voxel-driven-forward-projection-for-iterative-reconstruction-of-cone-beam-ct
#1
Yi Du, Gongyi Yu, Xincheng Xiang, Xiangang Wang
BACKGROUND: For cone-beam computed tomography (CBCT), which has been playing an important role in clinical applications, iterative reconstruction algorithms are able to provide advantageous image qualities over the classical FDK. However, the computational speed of iterative reconstruction is a notable issue for CBCT, of which the forward projection calculation is one of the most time-consuming components. METHOD AND RESULTS: In this study, the cone-beam forward projection problem using the voxel-driven model is analysed, and a GPU-based acceleration method for CBCT forward projection is proposed with the method rationale and implementation workflow detailed as well...
January 5, 2017: Biomedical Engineering Online
https://www.readbyqxmd.com/read/28079527/binary-moving-blocker-based-scatter-correction-in-cone-beam-computed-tomography-with-width-truncated-projections-proof-of-concept
#2
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/28079526/a-measurement-based-generalized-source-model-for-monte-carlo-dose-simulations-of-ct-scans
#3
Xin Ming, Yuanming Feng, Ransheng Liu, Chengwen Yang, Li Zhou, Hezheng Zhai, Jun Deng
The goal of this study is to present a generalized source model (GSM) for accurate Monte Carlo dose simulations of CT scans based solely on the measurement data without a priori knowledge of scanner specifications. The proposed generalized source model consists of an extended circular source located at x-ray target level with its energy spectrum, source distribution and fluence distribution derived from a set of measurement data conveniently available in the clinic. Specifically, the central axis percent depth dose (PDD) curves measured in water and the cone output factors measured in air were used to derive the energy spectrum and the source distribution respectively with a Levenberg-Marquardt algorithm...
January 12, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28074785/deformable-registration-of-ct-and-cone-beam-ct-with-local-intensity-matching
#4
Seyoun Park, William Plishker, Harry Quon, John Wong, Raj Shekhar, Junghoon Lee
Cone-beam CT (CBCT) is a widely used intra-operative imaging modality in image-guided radiotherapy and surgery. A short scan followed by a filtered-backprojection is typically used for CBCT reconstruction. While data on the mid-plane (plane of source-detector rotation) is complete, off-mid-planes undergo different information deficiency and the computed reconstructions are approximate. This causes different reconstruction artifacts at off-mid-planes depending on slice locations, and therefore impedes accurate registration between CT and CBCT...
February 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28072990/-the-images-of-osteoarthrosis-associated-with-anterior-disc-displacement-without-reduction-detected-by-cone-beam-ct
#5
J H Han, J Lei, M Q Liu, K Y Fu
Objective: To analyze the radiological characteristics of the condylar bone in patients with anterior disc displacement without reduction of temporomandibular joint using cone-beam CT (CBCT), and to further investigate the clinical factors possibly associated with the early-stage osteoarthritic changes. Methods: Two hundred and four individuals (≤30 years old) diagnosed as unilateral anterior disc displacement without reduction (disease duration≤1 year) were recruited. CBCT images of bilateral condyles were independently evaluated by two assessors and documented...
January 9, 2017: Zhonghua Kou Qiang Yi Xue za Zhi, Zhonghua Kouqiang Yixue Zazhi, Chinese Journal of Stomatology
https://www.readbyqxmd.com/read/28072395/evaluation-of-adaptive-treatment-planning-for-patients-with-non-small-cell-lung-cancer
#6
Hualiang Zhong, Salim Siddiqui, Benjamin Movsas, Indrin Chetty
The purpose of this study was to develop metrics to evaluate uncertainties in deformable dose accumulation (DDA) for patients with non-small cell lung cancer (NSCLC). Initial treatment plans (primary) and cone-beam CT (CBCT) images were retrospectively processed for seven NSCLC patients, who showed significant tumor regression during the course of treatment. Each plan was developed with IMRT for 2 Gy��33 fractions. A B-spline-based DIR algorithm was used to register weekly CBCT images to a reference image acquired at fraction 21 and the resultant displacement vector fields (DVFs) were then modified using a finite element method (FEM)...
January 10, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28069053/influence-of-daily-imaging-on-plan-quality-and-normal-tissue-toxicity-for-prostate-cancer-radiotherapy
#7
Katharina Bell, Marina Heitfeld, Norbert Licht, Christian Rübe, Yvonne Dzierma
BACKGROUND: Modern radiotherapy offers various possibilities for image guided verification of patient positioning. Different clinically relevant IGRT (image guided radiotherapy) scenarios were considered with regard to their influence on dosimetric plan quality and normal tissue complication probability (NTCP). METHODS: This study is based on treatment plans of 50 prostate patients. We evaluate the clinically performed IGRT and simulate the influence of different daily IGRT scenarios on plan quality...
January 10, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28068300/early-postoperative-imaging-of-the-labyrinth-by-cone-beam-ct-after-stapes-surgery-for-otosclerosis-with-correlation-to-audiovestibular-outcome
#8
Aurélie Vandevoorde, Marc T Williams, Elsa Ukkola-Pons, Mary Daval, Denis Ayache
BACKGROUND: Sensorineural complications of stapes surgery are rare but potentially serious. Imaging is usually performed to identify an underlying cause, such as excessive intravestibular penetration of the prosthesis or pneumolabyrinth suggesting perilymphatic fistula. Unfortunately, there is very little data in an unselected series of uneventful patients.The aim of this study was to analyze the depth of prosthesis penetration within the vestibule and the rate of pneumolabyrinth the day or the day after the procedure by performing a cone beam computed tomography of the temporal bone in a cohort of unselected patients, and to correlate imaging findings to clinical outcome...
February 2017: Otology & Neurotology
https://www.readbyqxmd.com/read/28061010/scatter-correction-using-a-primary-modulator-on-a-clinical-angiography-c-arm-ct-system
#9
Bastian Bier, Martin Berger, Andreas Maier, Marc Kachelrieß, Ludwig Ritschl, Kerstin Műller, Jang-Hwan Choi, Rebecca Fahrig
PURPOSE: Cone-beam computed tomography (CBCT) suffers from a large amount of scatter, resulting in severe scatter artifacts in the reconstructions. Recently, a new scatter correction approach, called improved primary modulator scatter estimation (iPMSE), was introduced. That approach utilizes a primary modulator that is inserted between the X-ray source and the object. This modulation enables estimation of the scatter in the projection domain by optimizing an objective function with respect to the scatter estimate...
January 6, 2017: Medical Physics
https://www.readbyqxmd.com/read/28052126/the-extent-of-the-crack-on-artificial-simulation-models-with-cbct-and-periapical-radiography
#10
Shuang Wang, Yiran Xu, Zhengyan Shen, Lijun Wang, Feng Qiao, Xu Zhang, Minghua Li, Ligeng Wu
BACKGROUND: The aim of this study was to investigate the extent of the crack of a cracked tooth on an artificial simulation model with Periapical Radiography (PR) and cone beam computed tomography (CBCT) in vitro, providing the basis for early diagnosis and an appropriate treatment plan. METHODS: Forty-four teeth with different extents of artificial cracks, created by exposure to liquid nitrogen after hot water at 100°C, were collected. They were subjected to PR and CBCT...
2017: PloS One
https://www.readbyqxmd.com/read/28050572/comparison-of-a-novel-weightbearing-cone-beam-computed-tomography-scanner-versus-a-conventional-computed-tomography-scanner-for-measuring-patellar-instability
#11
John Marzo, Melissa Kluczynski, Anthony Notino, Leslie Bisson
BACKGROUND: Conventional computed tomography (CT) images are routinely used for diagnosing patellofemoral instability and are obtained with the patient in a supine position, nonweightbearing, with the knee in full extension, and with leg muscles relaxed. A new portable extremity cone beam CT (CBCT) scanner has been developed that may allow for more accurate diagnosis, as imaging can be performed with the patient standing, the knee flexed, and with leg muscles active. PURPOSE/HYPOTHESIS: The purpose of this study was to compare CT measurements of patellar alignment on a prototype scanner versus conventional scanner in patients with known patellar instability...
December 2016: Orthopaedic Journal of Sports Medicine
https://www.readbyqxmd.com/read/28048931/su-f-t-638-is-there-a-need-for-immobilization-in-srs
#12
K Masterova, A Sethi, D Anderson, V Prabhu, I Rusu, S Gros, E Melian
PURPOSE: Frameless Stereotactic radiosurgery (SRS) is increasingly used in the clinic. Cone-Beam CT (CBCT) to simulation-CT match has replaced the 3-dimensional coordinate based set up using a stereotactic localizing frame. The SRS frame however served as both a localizing and immobilizing device. We seek to measure the quality of frameless (mask based) and frame based immobilization and evaluate its impact on target dose. METHODS: Each SRS patient was set up by kV on-board imaging (OBI) and then fine-tuned with CBCT...
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
#13
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 Software™ that aligned and deformed pCT into daily CBCT images in two steps: (1) rigid shifts applied after daily CBCT imaging to align patient anatomy to the pCT and (2) normalized intensity-based deformable registration to account for interfractional anatomical variations...
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
#14
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/28048864/su-f-j-41-experimental-validation-of-a-cascaded-linear-system-model-for-mvcbct-with-a-multi-layer-epid
#15
Y Hu, R Fueglistaller, J Rottmann, M Myronakis, A Wang, D Shedlock, D Morf, J Star-Lack, R Berbeco
PURPOSE: The purpose of this study was to validate the use of a cascaded linear system model for MV cone-beam CT (CBCT) using a multi-layer (MLI) electronic portal imaging device (EPID) and provide experimental insight into image formation. A validated 3D model provides insight into salient factors affecting reconstructed image quality, allowing potential for optimizing detector design for CBCT applications. METHODS: A cascaded linear system model was developed to investigate the potential improvement in reconstructed image quality for MV CBCT using an MLI EPID...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048844/su-f-j-70-monte-carlo-study-on-a-cone-beam-computed-tomography-using-a-cross-type-carbon-fiber-antiscatter-grid
#16
K Usui, T Inoue, C Kurokawa, S Sugimoto, K Sasai, K Ogawa
PURPOSE: If a cone-beam computed tomography (CBCT) image can be used for adaptive radiotherapy (ART), an irradiated actual dose distribution can be verified on every treatment day. However, a CBCT image is commonly degraded by scattered photons and thus cannot be directly used for dose calculation. The purpose of the present study is to evaluate whether a cross-type carbon fiber antiscatter grid improves CBCT image quality using a Monte Carlo (MC) method for achieving CBCT-based ART. METHODS: We designed a new carbon fiber (C6 H10 O5 ) interspaced grid, which allows the grid ratio to be increased while maintaining the transmission of primary photons...
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
#17
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/28048776/su-f-j-77-variations-in-the-displacement-vector-fields-calculated-by-different-deformable-image-registration-algorithms-used-in-helical-axial-and-cone-beam-ct-images-of-a-mobile
#18
I Ali, J Jaskowiak, N Alsbou, S Ahmad
PURPOSE: To investigate quantitatively the displacement-vector-fields (DVF) obtained from different deformable image registration algorithms (DIR) in helical (HCT), axial (ACT) and cone-beam CT (CBCT) to register CT images of a mobile phantom and its correlation with motion amplitudes and frequencies. METHODS: HCT, ACT and CBCT are used to image a mobile phantom which includes three targets with different sizes that are manufactured from water-equivalent material and embedded in low density foam...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048745/tu-d-brc-01-novel-applications-for-current-epid-technology
#19
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/28048739/tu-ab-207a-03-image-quality-dose-and-clinical-applications
#20
F Dong
: Practicing medical physicists are often time charged with the tasks of evaluating and troubleshooting complex image quality issues related to CT scanners. This course will equip them with a solid and practical understanding of common CT imaging chain and its major components with emphasis on acquisition physics and hardware, reconstruction, artifacts, image quality, dose, and advanced clinical applications. The core objective is to explain the effects of these major system components on the image quality...
June 2016: Medical Physics
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