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iterative model reconstruction

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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/28081011/spectrum-reconstruction-method-based-on-the-detector-response-model-calibrated-by-x-ray-fluorescence
#2
Ruizhe Li, Liang Li, Zhiqiang Chen
Accurate estimation of distortion-free spectra is important but difficult in various applications, especially for spectral computed tomography. Two key problems must be solved to reconstruct the incident spectrum. One is the acquisition of the detector energy response. It can be calculated by Monte Carlo simulation, which requires detailed modeling of the detector system and a high computational power. It can also be acquired by establishing a parametric response model and be calibrated using monochromatic x-ray sources, such as synchrotron sources or radioactive isotopes...
February 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28066840/task-based-design-of-fluence-field-modulation-in-ct-for-model-based-iterative-reconstruction
#3
Grace J Gang, Jeffrey H Siewerdsen, J Webster Stayman
A task-driven imaging framework for prospective fluence field modulation (FFM) is developed in this paper. The design approach uses a system model that includes a parameterized FFM acquisition and model-based iterative reconstruction (MBIR) for image formation. Using prior anatomical knowledge (e.g. from a low-dose 3D scout image), accurate predictions of spatial resolution and noise as a function of FFM are integrated into a task-based objective function. Specifically, detectability index (d'), a common metric for task-based image quality assessment, is computed for a specific formulation of the imaging task...
July 2016: Conference Proceedings of International Conference on Image Formation in X-Ray Computed Tomography
https://www.readbyqxmd.com/read/28065380/iterative-model-reconstruction-reduces-calcified-plaque-volume-in-coronary-ct-angiography
#4
Mihály Károlyi, Bálint Szilveszter, Márton Kolossváry, Richard A P Takx, Csilla Celeng, Andrea Bartykowszki, Ádám L Jermendy, Alexisz Panajotu, Júlia Karády, Rolf Raaijmakers, Walter Giepmans, Béla Merkely, Pál Maurovich-Horvat
OBJECTIVE: To assess the impact of iterative model reconstruction (IMR) on calcified plaque quantification as compared to filtered back projection reconstruction (FBP) and hybrid iterative reconstruction (HIR) in coronary computed tomography angiography (CTA). METHODS: Raw image data of 52 patients who underwent 256-slice CTA were reconstructed with IMR, HIR and FBP. We evaluated qualitative, quantitative image quality parameters and quantified calcified and partially calcified plaque volumes using automated software...
February 2017: European Journal of Radiology
https://www.readbyqxmd.com/read/28059562/spatial-and-contrast-resolution-of-ultralow-dose-dentomaxillofacial-ct-imaging-using-iterative-reconstruction-technology
#5
Gerlig Widmann, Alexander Bischel, Andreas Stratis, Hilde Bosmans, Reinhilde Jacobs, Eva-Maria Gassner, Wolfgang Puelacher, Ruben Pauwels
OBJECTIVE: The objective of this study was to determine how iterative reconstruction technology (IRT) influences contrast and spatial resolution in ultralow dose dentomaxillofacial computed tomography (CT) imaging. METHODS: A polymethyl methacrylate phantom with various inserts was scanned using a reference protocol at CTDIvol 36.56 mGy, a sinus protocol at 18.28 mGy, and ultralow dose protocols at 4.17, 2.36, 0.99, and 0.53 mGy. All datasets were reconstructed using filtered back projection (FBP) and the following IRTs: adaptive statistical iterative reconstructions (ASIR-50, ASIR-100), and model-based iterative reconstruction (MBIR)...
January 6, 2017: Dento Maxillo Facial Radiology
https://www.readbyqxmd.com/read/28058482/comparison-of-the-effects-of-model-based-iterative-reconstruction-and-filtered-back-projection-algorithms-on-software-measurements-in-pulmonary-subsolid-nodules
#6
Julien G Cohen, Hyungjin Kim, Su Bin Park, Bram van Ginneken, Gilbert R Ferretti, Chang Hyun Lee, Jin Mo Goo, Chang Min Park
OBJECTIVES: To evaluate the differences between filtered back projection (FBP) and model-based iterative reconstruction (MBIR) algorithms on semi-automatic measurements in subsolid nodules (SSNs). METHODS: Unenhanced CT scans of 73 SSNs obtained using the same protocol and reconstructed with both FBP and MBIR algorithms were evaluated by two radiologists. Diameter, mean attenuation, mass and volume of whole nodules and their solid components were measured. Intra- and interobserver variability and differences between FBP and MBIR were then evaluated using Bland-Altman method and Wilcoxon tests...
January 5, 2017: European Radiology
https://www.readbyqxmd.com/read/28055250/assessment-of-chest-ct-at-ctdivol-less-than-1-mgy-with-iterative-reconstruction-techniques
#7
Atul Padole, Subba Digumarthy, Efren Flores, Rachna Madan, Shelly Mishra, Amita Sharma, Mannudeep K Kalra
OBJECTIVES: To assess the image quality of chest CT reconstructed with image-based (SafeCT), adaptive statistical (ASIR), and model based (MBIR) iterative reconstruction techniques (IRTs) at CTDIvol less than 1 mGy. METHODS: In an IRB approved study, 25 patients gave written informed consent for acquisition of three Reduced Dose (RD) (0.25, 0.4, 0.8 mGy) chest CT after standard of care CT (8 mGy) on a 64-channel multi-detector CT (MDCT) and reconstructed with SafeCT, ASIR, and MBIR...
January 5, 2017: British Journal of Radiology
https://www.readbyqxmd.com/read/28048875/su-f-j-185-detection-of-low-contrast-objects-optimization-of-ct-simulation-reconstruction-protocol-parameters
#8
S Alani, A Schlocker, N Honig, B Corn
PURPOSE: CT simulation has become an integral component of modern RT planning and therefore must be continually optimized. We evaluated the detection of small and low-contrast regions in images obtained during CT simulation. METHODS: A CT phantom containing a contrast detail modulus for detection of low-contrast structures was used to optimize the CT reconstruction protocol for abdomen. The parameters (A) Pitch, (B) Reconstruction Filter, and (C) Rotation Time type were varied for assessment of image quality...
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
#9
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/28048785/su-f-j-08-quantitative-spect-imaging-of-ra-223-in-a-phantom
#10
J Yue, R Hobbs, G Sgouros, E Frey
PURPOSE: Ra-223 therapy of prostate cancer bone metastases is being used to treat patients routinely. However, the absorbed dose distribution at the macroscopic and microscopic scales remains elusive, due to the inability to image the small activities injected. Accurate activity quantification through imaging is essential to calculate the absorbed dose in organs and sub-units in radiopharmaceutical therapy, enabling personalized absorbed dose-based treatment planning methodologies and more effective and optimal treatments...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048784/su-g-206-10-low-contrast-detectability-vs-dose-for-ct-images-reconstructed-using-filtered-backprojection-and-iterative-reconstruction-assessment-with-a-model-observer
#11
C Favazza, A Ferrero, K McMillan, M Bruesewitz, L Yu, S Leng, J Kofler, C McCollough
PURPOSE: To evaluate CT low-contrast detectability at different dose levels in images reconstructed using filtered backprojection (FBP) and iterative reconstruction (IR). METHODS: A validated channelized Hotelling observer (CHO) model was used to detect low contrast objects in images of a helical CT phantom (Model 061, CIRS) using an Aquilion Prime 160 scanner (Toshiba Medical Systems). Twenty-one different objects of 7 diameters (2.4, 3.2, 4.6, 6.3, 9.5, and 10 mm) and 3 contrast levels (∼10, 15, and 25 HU) were evaluated...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048715/tu-d-207a-03-quantitative-assessment-of-ct-systems-with-iterative-image-reconstruction-algorithms
#12
K Li
: In recent several years, motivated by the need to reduce radiation doses in CT exams, all of the major CT manufacturers have commercialized different iterative image reconstruction techniques and these innovative techniques were used in clinical routines with increasing popularity. However, due to the intrinsic nonlinearity of these new techniques, the well accepted quantitative image quality assessment metrics such as spatial resolution and contrast to noise ratio are not sufficient to provide the needed quantitative metrics for assessing image quality and for guiding the CT scan protocol optimization...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048567/su-c-bra-07-variability-of-patient-specific-motion-models-derived-using-different-deformable-image-registration-algorithms-for-lung-cancer-stereotactic-body-radiotherapy-sbrt-patients
#13
S Dhou, D Ionascu, J Lewis, C Williams
PURPOSE: To study the variability of patient-specific motion models derived from 4-dimensional CT (4DCT) images using different deformable image registration (DIR) algorithms for lung cancer stereotactic body radiotherapy (SBRT) patients. METHODS: Motion models are derived by 1) applying DIR between each 4DCT image and a reference image, resulting in a set of displacement vector fields (DVFs), and 2) performing principal component analysis (PCA) on the DVFs, resulting in a motion model (a set of eigenvectors capturing the variations in the DVFs)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048528/we-h-206-01-photoacoustic-tomography-multiscale-imaging-from-organelles-to-patients-by-ultrasonically-beating-the-optical-diffusion-limit
#14
L Wang
: Lihong V. Wang: Photoacoustic tomography (PAT), combining non-ionizing optical and ultrasonic waves via the photoacoustic effect, provides in vivo multiscale functional, metabolic, and molecular imaging. Broad applications include imaging of the breast, brain, skin, esophagus, colon, vascular system, and lymphatic system in humans or animals. Light offers rich contrast but does not penetrate biological tissue in straight paths as x-rays do. Consequently, high-resolution pure optical imaging (e...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048414/th-ab-207a-05-a-fully-automated-pipeline-for-generating-ct-images-across-a-range-of-doses-and-reconstruction-methods
#15
S Young, P Lo, J Hoffman, M Wahi-Anwar, F Noo, M Brown, M McNitt-Gray
PURPOSE: To evaluate the robustness of CAD or Quantitative Imaging methods, they should be tested on a variety of cases and under a variety of image acquisition and reconstruction conditions that represent the heterogeneity encountered in clinical practice. The purpose of this work was to develop a fully-automated pipeline for generating CT images that represent a wide range of dose and reconstruction conditions. METHODS: The pipeline consists of three main modules: reduced-dose simulation, image reconstruction, and quantitative analysis...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048383/th-ef-bra-01-5d-respiratory-motion-model-based-iterative-reconstruction-method-for-4dcbct
#16
J Liu, D Low, H Gao
PURPOSE: The 4DCBCT image reconstruction suffers from the insufficient number of projections and the error from projection binning. We have recently developed a 5D respiratory motion model based iterative reconstruction method (5D method) for 4DCBCT in a proof-of-concept 2D setting. The 5D method reconstructs a reference image and two time-independent vector fields without projection binning, based on which any temporal phase at each projection can be generated. As a result, the 5D method needs fewer number of projections and is free from binning error...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048150/th-cd-207b-04-is-ttf-a-true-representation-of-the-sharpness-property-of-a-non-linear-ct-system
#17
M Robins, J Solomon, E Samei
PURPOSE: To investigate if the task-transfer-function (TTF) accurately models the transfer properties of a CT system for lung nodule imaging. METHODS: An anthropomorphic lung phantom was imaged using a standard chest protocol on a clinical CT scanner with and without 24 physically inserted synthetic lesions (nominal diameter: 8 - 10 mm). Images were reconstructed using FBP and iterative algorithm (SAFIRE, Siemens Healthcare). 3D TTF was measured using an established technique...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047997/tu-d-207a-00-quantitative-assessment-of-ct-systems-with-iterative-image-reconstruction-algorithms
#18
Guang-Hong Chen, Michael McNitt-Gray
: In recent several years, motivated by the need to reduce radiation doses in CT exams, all of the major CT manufacturers have commercialized different iterative image reconstruction techniques and these innovative techniques were used in clinical routines with increasing popularity. However, due to the intrinsic nonlinearity of these new techniques, the well accepted quantitative image quality assessment metrics such as spatial resolution and contrast to noise ratio are not sufficient to provide the needed quantitative metrics for assessing image quality and for guiding the CT scan protocol optimization...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047869/we-h-206-02-recent-advances-in-multi-modality-molecular-imaging-of-small-animals
#19
B Tsui
: Lihong V. Wang: Photoacoustic tomography (PAT), combining non-ionizing optical and ultrasonic waves via the photoacoustic effect, provides in vivo multiscale functional, metabolic, and molecular imaging. Broad applications include imaging of the breast, brain, skin, esophagus, colon, vascular system, and lymphatic system in humans or animals. Light offers rich contrast but does not penetrate biological tissue in straight paths as x-rays do. Consequently, high-resolution pure optical imaging (e...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047848/tu-h-campus-iep2-02-four-dimensional-coronary-artery-visualization-based-on-image-propagation
#20
B Liu, B Liang, X Xu, B Guo, R Wei, S Xu, F Zhou, Q Wu
PURPOSE: 4D visualization of coronary artery using X-ray angiograms rotationally acquired on C-arm has many valuable applications, like dynamic roadmapping. In this work we propose and validate a method to visualize 4D artery based on 3D coronary image propagation. METHODS: After sorting the angiograms into different cardiac phases using nearest-neighbor ECG gating, a high quality 3D coronary image was reconstructed at one phase using a motion-compensated iterative reconstruction method...
June 2016: Medical Physics
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