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CT imaging, increasing accuracy

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https://www.readbyqxmd.com/read/28105470/bladder-cancer-segmentation-in-ct-for-treatment-response-assessment-application-of-deep-learning-convolution-neural-network-a-pilot-study
#1
COMMENT
Kenny H Cha, Lubomir M Hadjiiski, Ravi K Samala, Heang-Ping Chan, Richard H Cohan, Elaine M Caoili, Chintana Paramagul, Ajjai Alva, Alon Z Weizer
Assessing the response of bladder cancer to neoadjuvant chemotherapy is crucial for reducing morbidity and increasing quality of life of patients. Changes in tumor volume during treatment is generally used to predict treatment outcome. We are developing a method for bladder cancer segmentation in CT using a pilot data set of 62 cases. 65 000 regions of interests were extracted from pre-treatment CT images to train a deep-learning convolution neural network (DL-CNN) for tumor boundary detection using leave-one-case-out cross-validation...
December 2016: Tomography: a Journal for Imaging Research
https://www.readbyqxmd.com/read/28101760/a-cad-of-fully-automated-colonic-polyp-detection-for-contrasted-and-non-contrasted-ct-scans
#2
Gökalp Tulum, Bülent Bolat, Onur Osman
PURPOSE: Computer-aided detection (CAD) systems are developed to help radiologists detect colonic polyps over CT scans. It is possible to reduce the detection time and increase the detection accuracy rates by using CAD systems. In this paper, we aimed to develop a fully integrated CAD system for automated detection of polyps that yields a high polyp detection rate with a reasonable number of false positives. METHODS: The proposed CAD system is a multistage implementation whose main components are: automatic colon segmentation, candidate detection, feature extraction and classification...
January 18, 2017: International Journal of Computer Assisted Radiology and Surgery
https://www.readbyqxmd.com/read/28094413/electrical-impedance-tomography-for-lung-ventilation-monitoring-of-the-dog
#3
Simon Gloning, Korbinian Pieper, Martin Zoellner, Andrea Meyer-Lindenberg
BACKGROUND: Electrical impedance tomography (EIT) is a radiation free technique which takes advantage of the different electrical conductivities of different tissues. Its main field of application is lung ventilation monitoring. The aim of this prospective study was to evaluate the feasibility of collecting EIT information on a sample of dogs with different thoracic shapes under clinical conditions by connecting an electrode belt without fur clipping. MATERIAL AND METHODS: Fifteen pulmonary healthy dogs were anaesthetized, positioned in sternal recumbency and ventilated in a pressure-controlled mode at three different positive end-expiratory pressure levels (PEEP) of 0, 5 and 10 cmH2O for five breaths each, with a peak inspiratory pressure of 15 cmH2O...
January 17, 2017: Tierärztliche Praxis. Ausgabe K, Kleintiere/Heimtiere
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
#4
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/28066887/the-effect-of-beam-purity-and-scanner-complexity-on-proton-ct-accuracy
#5
P Piersimoni, J Ramos-Méndez, T Geoghegan, V A Bashkirov, R W Schulte, B A Faddegon
PURPOSE: To determine the dependence of the accuracy in reconstruction of relative stopping power (RSP) with proton computerized tomography (pCT) scans on the purity of the proton beam and the technological complexity of the pCT scanner using standard phantoms and a digital representation of a pediatric patient. METHODS: The Monte Carlo method was applied to simulate the pCT scanner, using both a pure proton beam (uniform 200 MeV mono-energetic, parallel beam) and the Northwestern Medicine Chicago Proton Center (NMCPC) clinical beam in uniform scanning mode...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28060999/statistical-image-domain-multi-material-decomposition-for-dual-energy-ct
#6
Yi Xue, Ruoshui Ruan, Xiuhua Hu, Yu Kuang, Jing Wang, Yong Long, Tianye Niu
PURPOSE: Dual-energy CT (DECT) enhances tissue characterization because of its basis material decomposition capability. In addition to conventional two-material decomposition from DECT measurements, multi-material decomposition (MMD) is required in many clinical applications. To solve the ill-posed problem of reconstructing multiple-material images from dual-energy measurements, additional constraints are incorporated into the formulation, including volume and mass conservation and the assumptions that at most three materials in each pixel and various material types among pixels...
January 6, 2017: Medical Physics
https://www.readbyqxmd.com/read/28050972/registration-of-mri-to-intraoperative-radiographs-for-target-localization-in-spinal-interventions
#7
T De Silva, A Uneri, M D Ketcha, S Reaungamornrat, J Goerres, M W Jacobson, S Vogt, G Kleinszig, A J Khanna, J-P Wolinsky, J H Siewerdsen
Decision support to assist in target vertebra localization could provide a useful aid to safe and effective spine surgery. Previous solutions have shown 3D-2D registration of preoperative CT to intraoperative radiographs to reliably annotate vertebral labels for assistance during level localization. We present an algorithm (referred to as MR-LevelCheck) to perform 3D-2D registration based on a preoperative MRI to accommodate the increasingly common clinical scenario in which MRI is used instead of CT for preoperative planning...
January 4, 2017: Physics in Medicine and Biology
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
#8
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/28048798/su-f-j-88-comparison-of-two-deformable-image-registration-algorithms-for-ct-to-ct-contour-propagation
#9
A Gopal, H Xu, S Chen
PURPOSE: To compare the contour propagation accuracy of two deformable image registration (DIR) algorithms in the Raystation treatment planning system - the "Hybrid" algorithm based on image intensities and anatomical information; and the "Biomechanical" algorithm based on linear anatomical elasticity and finite element modeling. METHODS: Both DIR algorithms were used for CT-to-CT deformation for 20 lung radiation therapy patients that underwent treatment plan revisions...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048754/su-f-j-204-carbon-digitally-reconstructed-radiography-cdrr-a-gpu-based-tool-for-fast-and-versatile-carbonimaging-simulation
#10
M F Dias, J Seco, G Baroni, M Riboldi
PURPOSE: Research in carbon imaging has been growing over the past years, as a way to increase treatment accuracy and patient positioning in carbon therapy. The purpose of this tool is to allow a fast and flexible way to generate CDRR data without the need to use Monte Carlo (MC) simulations. It can also be used to predict future clinically measured data. METHODS: A python interface has been developed, which uses information from CT or 4DCT and thetreatment calibration curve to compute the Water Equivalent Path Length (WEPL) of carbon ions...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048744/su-f-t-119-development-of-heart-prediction-model-to-increase-accuracy-of-dose-reconstruction-for-radiotherapy-patients
#11
E Mosher, M Choi, E Jones, C Lee
PURPOSE: To assess individual variation in heart volume and location in order to develop a prediction model of the heart. This heart prediction model will be used to calculate individualized heart doses for radiotherapy patients in epidemiological studies. METHODS: Chest CT images for 30 adult male and 30 adult female patients were obtained from NIH Clinical Center. Image-analysis computer programs were used to segment the whole heart and 8 sub-regions and to measure the volume of each sub- region and the dimension of the whole heart...
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
#12
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
#13
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/28048652/tu-d-brb-00-dual-energy-ct-in-radiation-therapy
#14
Zacariah Labby
: Dual-energy CT technology is becoming increasingly available to the medical imaging community. In addition, several models of CT simulators sold for use in radiation therapy departments now feature dual-energy technology. The images provided by dual-energy CT scanners add new information to the radiation treatment planning process; multiple spectral components can be used to separate and identify material composition as well as generate virtual monoenergetic images. In turn, this information could be used to investigate pathologic processes, separate the properties of contrast agents from soft tissues, assess tissue response to therapy, and other applications of therapeutic interest...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048597/tu-h-campus-iep3-01-simultaneous-pet-restoration-and-pet-ct-co-segmentation-using-a-variational-method
#15
L Li, W Lu, S Tan
PURPOSE: PET images are usually blurred due to the finite spatial resolution, while CT images suffer from low contrast. Segment a tumor from either a single PET or CT image is thus challenging. To make full use of the complementary information between PET and CT, we propose a novel variational method for simultaneous PET image restoration and PET/CT images co-segmentation. METHODS: The proposed model was constructed based on the Γ-convergence approximation of Mumford-Shah (MS) segmentation model for PET/CT co-segmentation...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048563/we-ab-207b-05-correlation-of-normal-lung-density-changes-with-dose-after-stereotactic-body-radiotherapy-sbrt-for-early-stage-lung-cancer
#16
Q Wu, S Devpura, K Feghali, C Liu, M Ajlouni, B Movsas, I Chetty
PURPOSE: To investigate correlation of normal lung CT density changes with dose accuracy and outcome after SBRT for patients with early stage lung cancer. METHODS: Dose distributions for patients originally planned and treated using a 1-D pencil beam-based (PB-1D) dose algorithm were retrospectively recomputed using algorithms: 3-D pencil beam (PB-3D), and model-based METHODS: AAA, Acuros XB (AXB), and Monte Carlo (MC). Prescription dose was 12 Gy × 4 fractions...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048512/th-cd-202-04-evaluation-of-virtual-non-contrast-images-from-a-novel-split-filter-dual-energy-ct-technique
#17
J Huang, T Szczykutowicz, J Bayouth, J Miller
PURPOSE: To compare the ability of two dual-energy CT techniques, a novel split-filter single-source technique of superior temporal resolution against an established sequential-scan technique, to remove iodine contrast from images with minimal impact on CT number accuracy. METHODS: A phantom containing 8 tissue substitute materials and vials of varying iodine concentrations (1.7-20.1 mg I /mL) was imaged using a Siemens Edge CT scanner. Dual-energy virtual non-contrast (VNC) images were generated using the novel split-filter technique, in which a 120kVp spectrum is filtered by tin and gold to create high- and low-energy spectra with < 1 second temporal separation between the acquisition of low- and high-energy data...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048416/su-g-tep2-11-initial-evaluation-of-a-novel-split-filter-dual-energy-ct-for-use-in-radiation-oncology
#18
J Miller, J Huang, T Szczykutowicz, J Bayouth
PURPOSE: To perform an initial evaluation of a novel split-filter dual-energy CT (DECT) system with the goal of understanding the clinical utility and limitations of the system for radiation therapy. METHODS: Several phantoms were imaged using the split-filter DECT technique on the Siemens Edge CT scanner using a range of clinically-relevant doses. The optimum-contrast reconstruction, the mixed reconstruction, and the monoenergetic reconstructions (ranging from 40 keV to 190 keV) were evaluated...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048386/th-cd-206-03-evaluation-of-a-new-method-to-improve-atlas-based-segmentation-for-the-bladder-and-rectum
#19
A Nelson, S Pirozzi, S Chung
PURPOSE: Atlas segmentation for the bladder and rectum pose particular challenges due to variability in bladder filling and variability in rectal contents including air and fecal matter. Previously we evaluated atlas segmentation for high risk prostate cancer including the bladder and rectum. In the current study we sought to further improve automated segmentation results by utilizing a customized post-processing workflow for the bladder and rectum. METHODS: Pelvic CT scans for 32 subjects with prostate cancer were chosen and the bladder and rectum were first segmented using the Multi-5 atlas-based approach described in Pirozzi et al (IJROBP 2012)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048245/su-f-j-157-effect-of-contouring-uncertainty-in-post-implant-dosimetry-of-low-dose-rate-prostate-permanent-seed-brachytherapy
#20
S Mashouf, H Safigholi, T Merino, A Soliman, A Ravi, G Morton, W Song
PURPOSE: There is strong evidence relating post-implant dosimetry for low-dose-rate (LDR) prostate seed brachytherapy to local control rates. The delineation of the prostate on CT images, however, represents a challenge due to the lack of soft tissue contrast in order to identify the prostate borders. This study aims at quantifying the sensitivity of clinically relevant dosimetric parameters to uncertainty in the contouring of prostate. METHODS: CT images, post-op plans and contours of a cohort of patients (n=43) (low risk=55...
June 2016: Medical Physics
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