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https://www.readbyqxmd.com/read/28211367/high-quality-four-dimensional-cone-beam-ct-reconstruction-using-motion-compensated-total-variation-regularization
#1
Hua Zhang, Jianhua Ma, Zhaoying Bian, Dong Zeng, Qianjin Feng, Wufan Chen
Four dimensional cone-beam computed tomography (4D-CBCT) has great potential clinical value because its ability to describe tumor and organ motion. But the challenge in 4D-CBCT reconstruction is the limited number of projections at each phase, which resulting in the reconstruction full of noise and streak artifacts with the conventional analytical algorithms. To address this problem, in this paper, we propose a motion compensated total variation regularization approach which tries to maximum explore the temporal coherence of the spatial structures among 4D-CBCT phases...
February 17, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28203490/pulsatile-tinnitus-differential-diagnosis-and-radiological-work-up
#2
REVIEW
Sjoert A H Pegge, Stefan C A Steens, Henricus P M Kunst, Frederick J A Meijer
PURPOSE OF REVIEW: Identification of the underlying cause of pulsatile tinnitus is important for treatment decision making and for prognosis estimation. For this, an adequate diagnostic imaging strategy is crucial. RECENT FINDINGS: Both CT and MRI can be useful, and in general, these modalities provide complementary diagnostic information. The scanning protocol can be optimized based on the estimated a priori chance for finding specific pathology, or the need to rule out more rare but clinical significant disease...
2017: Current Radiology Reports
https://www.readbyqxmd.com/read/28191858/impact-of-the-pde4d-gene-polymorphism-and-additional-snp-snp-and-gene-smoking-interaction-on-ischemic-stroke-risk-in-chinese-han-population
#3
Xianxiang Wang, Zhongwu Sun, Yiquan Zhang, Xuefeng Tian, Qingxin Li, Jing Luo
AIMS: To investigate the association between phosphodiesterase 4D gene (PDE4D) gene single nucleotide polymorphisms (SNPs) and ischemic stroke (IS) risk, and impact of additional SNP- SNP and gene- smoking interaction on IS risk in Chinese population. METHODS: A total of 1228 subjects (666 males, 562 females) were selected, including 610 IS patients and 618 control subjects. Logistic regression model was used to examine the association between SNPs in PDE4D gene and IS risk...
February 13, 2017: Neurological Research
https://www.readbyqxmd.com/read/28140361/directional-sinogram-interpolation-for-motion-weighted-4d-cone-beam-ct-reconstruction
#4
Hua Zhang, Matthijs Kruis, Jan-Jakob Sonke
The image quality of respiratory sorted four-dimensional (4D) cone-beam (CB) computed tomography (CT) is often limited by streak artifacts due to insufficient projections. A motion weighted reconstruction (MWR) method is proposed to decrease streak artifacts and improve image quality. Firstly, respiratory correlated CBCT projections were interpolated by directional sinogram interpolation (DSI) to generate additional CB projections for each phase and subsequently reconstructed. Secondly, local motion was estimated by deformable image registration of the interpolated 4D CBCT...
January 31, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28133755/evaluation-of-motion-mitigation-using-abdominal-compression-in-the-clinical-implementation-of-pencil-beam-scanning-proton-therapy-of-liver-tumors
#5
Liyong Lin, Kevin Souris, Minglei Kang, Adam Glick, Haibo Lin, Sheng Huang, Kristin Stützer, Guillaume Janssens, Edmond Sterpin, John A Lee, Timothy D Solberg, James E McDonough, Charles B Simone, Edgar Ben-Josef
PURPOSE: To determine whether individual liver tumor patients can be safely treated with pencil beam scanning proton therapy. This study reports a planning preparation workflow that can be used for beam angle selection and the evaluation of the efficacy of abdominal compression (AC) to mitigate motion. METHODS: Four-dimensional computed tomography scans (4DCT) with and without AC were available from 10 liver tumor patients with fluoroscopy-proven motion reduction by AC, previously treated using photons...
December 9, 2016: Medical Physics
https://www.readbyqxmd.com/read/28133752/respiratory-motion-resolved-self-gated-4d-mri-using-rotating-cartesian-k-space-rock
#6
Fei Han, Ziwu Zhou, Minsong Cao, Yingli Yang, Ke Sheng, Peng Hu
PURPOSE: To propose and validate a respiratory motion resolved, self-gated (SG) 4D-MRI technique to assess patient-specific breathing motion of abdominal organs for radiation treatment planning. METHODS: The proposed 4D-MRI technique was based on the balanced steady-state free-precession (bSSFP) technique and 3D k-space encoding. A novel ROtating Cartesian K-space (ROCK) reordering method was designed that incorporates repeatedly sampled k-space centerline as the SG motion surrogate and allows for retrospective k-space data binning into different respiratory positions based on the amplitude of the surrogate...
January 30, 2017: Medical Physics
https://www.readbyqxmd.com/read/28128544/high-resolution-4d-pre-clinical-spect-ct-imaging-of-technetium-transport-within-a-heterogeneous-porous-media
#7
Mine Dogan, Stephen M J Moysey, Ruud M Ramakers, Timothy A DeVol, Frederik J Beekman, Harald C Groen, Brian A Powell
A dynamic (99m)Tc tracer experiment was performed to investigate the capabilities of combined pre-clinical single photon emission computed tomography (SPECT) and x-ray computed tomography (CT) for investigating transport in a heterogeneous porous medium. The experiment was conducted by continuously injecting a (99m)Tc solution into a column packed with 8 layers (i.e., soil, silica gel, and 0.2-4 mm glass beads). Within the imaging results it was possible to correlate observed features with objects as small as 2 mm for the SPECT and 0...
January 27, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28126751/application-of-time-resolved-3d-digital-subtraction-angiography-to-plan-cerebral-arteriovenous-malformation-radiosurgery
#8
K-K Chen, W-Y Guo, H-C Yang, C-J Lin, C-H F Wu, S Gehrisch, M Kowarschik, Y-T Wu, W-Y Chung
BACKGROUND AND PURPOSE: Time-resolved 3D-DSA (4D-DSA) enables viewing vasculature from any desired angle and time frame. We investigated whether these advantages may facilitate treatment planning and the feasibility of using 4D-DSA as a single imaging technique in AVM/dural arteriovenous fistula radiosurgery. MATERIALS AND METHODS: Twenty consecutive patients (8 dural arteriovenous fistulas and 12 AVMs; 13 men and 7 women; mean age, 45 years; range, 18-64 years) who were scheduled for gamma knife radiosurgery were recruited (November 2014 to October 2015)...
January 26, 2017: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/28113545/radiolucent-4d-ultrasound-imaging-system-design-and-application-to-radiotherapy-guidance
#9
Jeffrey Schlosser, Dimitre Hristov
Four-dimensional (4D) ultrasound (US) is an attractive modality for image guidance due to its real-time, non-ionizing, volumetric imaging capability with high soft tissue contrast. However, existing 4D US imaging systems contain large volumes of metal which interfere with diagnostic and therapeutic ionizing radiation in procedures such as CT imaging and radiation therapy. This study aimed to design and characterize a novel 4D Radiolucent Remotely-Actuated UltraSound Scanning (RRUSS) device that overcomes this limitation...
April 27, 2016: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28103549/cardiac-image-reconstruction-via-non-linear-motion-correction-based-on-partial-angle-reconstructed-images
#10
Seungeon Kim, Yongjin Chang, Jong Beom Ra
Even though the X-ray CT scan is considered suitable for fast imaging, motion-artifact-free cardiac imaging is still an important issue because the gantry rotation speed is not fast enough compared with the heart motion. To obtain a heart image with less motion artifacts, a motion estimation (ME) and motion compensation (MC) approach is usually adopted. In this paper, we propose a ME/MC algorithm that can estimate a non-linear heart motion model from a sinogram with a rotation angle of less than 360°. In this algorithm, we first assume the heart motion to be non-rigid but linear, and thereby estimate an initial 4D motion vector field (MVF) during a half rotation by using conjugate partial angle reconstructed images, as in our previous ME/MC algorithm...
January 17, 2017: IEEE Transactions on Medical Imaging
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
#11
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
#12
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
#13
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
#14
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-4d-intensity-modulated-arc-therapy-for-tumor-tracking-with-a-multileaf-collimator
#15
Ying Niu, Gregory T Betzel, Xiaocheng Yang, Minzhi Gui, William C Parke, Byongyong Yi, Cedric X 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...
February 21, 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
#16
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
#17
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
#18
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
#19
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
#20
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
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