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https://www.readbyqxmd.com/read/28100836/a-sterile-animal-model-for-neuroinflammation
#1
Lawrence K Fung
MRI-guided pulsed focused ultrasound combined with systemic infusion of contrast agent microbubbles induces local neuroinflammation in the rat.
January 18, 2017: Science Translational Medicine
https://www.readbyqxmd.com/read/28096104/recent-developments-in-the-surgical-management-of-paediatric-epilepsy
#2
REVIEW
Vijay M Ravindra, Matthew T Sweney, Robert J Bollo
Among the 1% of children affected by epilepsy, failure of pharmacological therapy and early age of seizure onset can lead to worse long-term cognitive outcomes, mental health disorders and impaired functional status. Surgical management often improves functional and cognitive outcomes in children with medically refractory epilepsy, especially when seizure remission is achieved. However, surgery remains underused in children with drug-resistant epilepsy, creating a large treatment gap. Several recent innovations have led to considerable improvement in surgical technique, including the recent development of minimally invasive diagnostic and therapeutic techniques such as stereotactic EEG, transcranial magnetic stimulation, MRI-guided laser ablation, as well as novel paradigms of neurostimulation...
January 17, 2017: Archives of Disease in Childhood
https://www.readbyqxmd.com/read/28094199/risk-of-prostate-cancer-diagnosis-and-mortality-in-men-with-a-benign-initial-transrectal-ultrasound-guided-biopsy-set-a-population-based-study
#3
Nina Klemann, M Andreas Røder, J Thomas Helgstrand, Klaus Brasso, Birgitte G Toft, Ben Vainer, Peter Iversen
BACKGROUND: The risk of missing prostate cancer in the transrectal ultrasound-guided systematic biopsies of the prostate in men with suspected prostate cancer is a key problem in urological oncology. Repeat biopsy or MRI-guided biopsies have been suggested to increase sensitivity for diagnosis of prostate cancer, but the risk of disease-specific mortality in men who present with raised prostate-specific antigen (PSA) concentration and a benign initial biopsy result remains unknown. We investigated the risk of overall and prostate cancer-specific mortality in men with a benign initial biopsy set...
January 13, 2017: Lancet Oncology
https://www.readbyqxmd.com/read/28067975/assessment-of-acute-thermal-damage-volumes-in-muscle-using-magnetization-prepared-3d-t2-weighted-imaging-following-mri-guided-high-intensity-focused-ultrasound-therapy
#4
Robert M Staruch, Joris Nofiele, Jamie Walker, Chenchen Bing, Ananth J Madhuranthakam, April Bailey, Young-Sun Kim, Avneesh Chhabra, Dennis Burns, Rajiv Chopra
PURPOSE: To evaluate magnetization-prepared 3D T2 -weighted magnetic resonance imaging (MRI) measurements of acute tissue changes produced during ablative MR high-intensity focused ultrasound (MR-HIFU) exposures. MATERIALS AND METHODS: A clinical MR-HIFU system (3T) was used to generate thermal lesions (n = 24) in the skeletal muscles of three pigs. T1 -weighted, 2D T2 -weighted, and magnetization-prepared 3D T2 -weighted sequences were acquired before and after therapy to evaluate tissue changes following ablation...
January 9, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28048869/su-f-j-145-mri-guided-interventional-boost-radiotherapy-for-rectal-cancer-investigating-the-feasibility-of-adapting-the-anatomy
#5
J J E Kleijnen, A M Couwenberg, B van Asselen, J J W Lagendijk, M Intven, B W Raaymakers
PURPOSE: The recent development of an MRI-linac allows adaptation of treatments to the anatomy of the moment. This anatomy, in turn, could be altered into a more favorable situation for radiotherapy purposes. The purpose of this study is to investigate the potential dosimetric benefits of manipulating rectal anatomy in MRI-guided interventional external-beam radiotherapy for rectal cancer. METHODS: For this retrospective analysis, four patients (1M/3F) diagnosed with rectal cancer were included...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048833/su-g-iep1-13-sub-nyquist-dynamic-mri-via-prior-rank-intensity-and-sparsity-model-prism
#6
B Jiang, H Gao
PURPOSE: Accelerated dynamic MRI is important for MRI guided radiotherapy. Inspired by compressive sensing (CS), sub-Nyquist dynamic MRI has been an active research area, i.e., sparse sampling in k-t space for accelerated dynamic MRI. This work is to investigate sub-Nyquist dynamic MRI via a previously developed CS model, namely Prior Rank, Intensity and Sparsity Model (PRISM). METHODS: The proposed method utilizes PRISM with rank minimization and incoherent sampling patterns for sub-Nyquist reconstruction...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048649/tu-h-bra-07-design-construction-and-installation-of-an-experimental-beam-line-for-the-development-of-mri-linac-compatible-electron-accelerator
#7
B Whelan, P Keall, L Holloway, S Gierman, J Schmerge, S Tantawi, A Tremaine, A Trautwein, B Scott, R Fahrig
PURPOSE: MRI guided radiation therapy (MRIgRT) is a rapidly growing field; however, Linac operation in MRI fringe fields represents an ongoing challenge. We have previously shown in-silico that Linacs could be redesigned to function in the in-line orientation with no magnetic shielding by adopting an RF-gun configuration. Other authors have also published insilico studies of Linac operation in magnetic fields; however to date no experimental validation data is published. This work details the design, construction, and installation of an experimental beam line to validate our in-silico results...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048360/mo-b-201-03-mri-guided-tracking-and-gating
#8
O Green
: The motion management in stereotactic body radiation therapy (SBRT) is a key to success for a SBRT program, and still an on-going challenging task. A major factor is that moving structures behave differently than standing structures when examined by imaging modalities, and thus require special considerations and employments. Understanding the motion effects to these different imaging processes is a prerequisite for a decent motion management program. The commonly used motion control techniques to physically restrict tumor motion, if adopted correctly, effectively increase the conformity and accuracy of hypofractionated treatment...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048331/su-f-j-110-mri-guided-single-session-simulation-online-adaptation-and-treatment
#9
P Hill, M Geurts, K Mittauer, J Bayouth
PURPOSE: To develop a combined simulation and treatment workflow for MRI-guided radiation therapy using the ViewRay treatment planning and delivery system. METHODS: Several features of the ViewRay MRIdian planning and treatment workflows are used to simulate and treat patients that require emergent radiotherapy. A simple "pre-plan" is created on diagnostic imaging retrieved from radiology PACS, where conformal fields are created to target a volume defined by a physician based on review of the diagnostic images and chart notes...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048163/th-f-202-01-mri-basics
#10
W Miller
: MRI has excellent soft tissue contrast and can provide both anatomical and physiological information. It is becoming increasingly important in radiation therapy for treatment planning, image-guided radiation therapy, and treatment assessment. It is critically important at this time point to educate and update our medical physicists about MRI to prepare for the upcoming surge of MRI applications in radiation therapy. This session will review important basics of MR physics, pulse sequence designs, and current radiotherapy application, as well as showcase exciting new developments in MRI that can be potentially useful in radiation therapy...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048140/mo-fg-campus-jep2-05-mri-guided-single-fraction-boost-delivery-on-individual-axillary-lymph-nodes
#11
T C F van Heijst, N Hoekstra, M E P Philippens, D Eschbach, J J W Lagendijk, H J G D van den Bongard, B van Asselen
PURPOSE: The Utrecht MRI-linac (MRL) design enables new MR-guided radiotherapy (RT) approaches. This is a feasibility study for a single-fraction high dose (boost) to individual lymph nodes (LNs) in breast-cancer patients, after breast-conserving surgery (BCS) and hypofractionated whole-breast irradiation (WBI) with conventional axillary RT (AxRT). METHODS: After written informed consent, 5 breast-cancer patients (cT1-3N0) were enrolled (NL500460.041.14 trial) and underwent 1...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048129/su-f-i-15-evaluation-of-a-new-mr-compatible-respiratory-motion-device-at-3t
#12
A Soliman, B Chugh, B Keller, A Sahgal, W Song
PURPOSE: Recent advances in MRI-guided radiotherapy has inspired the development of MRI-compatible motion devices that simulate patient periodic motion in the scanner, particularly respiratory motion. Most commercial devices rely on non MR-safe ferromagnetic stepper motors which are not practical for regular QA testing. This work evaluates the motion performance of a new fully MRI compatible respiratory motion device at 3T. METHODS: The QUASAR™ MRI-compatible respiratory motion phantom has been recently developed by Modus QA Inc...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048059/tu-ab-202-06-quantitative-evaluation-of-deformable-image-registration-in-mri-guided-adaptive-radiation-therapy
#13
K Mooney, T Zhao, Y Duan, M Zhang, O Green, S Mutic, D Yang
PURPOSE: To assess the performance of the deformable image registration algorithm used for MRI-guided adaptive radiation therapy using image feature analysis. METHODS: MR images were collected from five patients treated on the MRIdian (ViewRay, Inc., Oakwood Village, OH), a three head Cobalt-60 therapy machine with an 0.35 T MR system. The images were acquired immediately prior to treatment with a uniform 1.5 mm resolution. Treatment sites were as follows: head/neck, lung, breast, stomach, and bladder...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048042/tu-ab-bra-07-distortion-free-3d-diffusion-mri-on-an-mri-guided-radiotherapy-system-for-longitudinal-tumor-response-assessment
#14
Y Gao, Y Yang, N Rangwala, M Cao, D Low, P Hu
PURPOSE: To develop a reliable, 3D distortion-free diffusion MRI technique for longitudinal tumor response assessment and MRI-guided adaptive radiotherapy(RT). METHODS: A diffusion prepared 3D turbo spin echo readout (DP-TSE) sequence was developed and compared with the conventional diffusion-weighted single-shot echo-planar-imaging (DW-ssEPI) sequence in a commercially available diffusion phantom, and one head-and-neck and one brain cancer patient on an MRI-guided RT system (ViewRay)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047917/tu-h-campus-jep2-01-inter-observer-delineation-comparison-of-visible-glandular-breast-tissue-on-magnetic-resonance-imaging-and-computed-tomography-prone-and-supine
#15
E M Pogson, G Delaney, V Ahern, M Boxer, S David, M Dimigen, J Harvey, E Koh, K Lim, G Papadatos, M Yap, V Batumalai, P Metcalfe, L Holloway
PURPOSE: Breast cancers predominantly arise from Glandular Breast Tissue (GBT). If the GBT can be treated effectively post-operatively utilising radiotherapy this may be adequate volumetric coverage for adjuvant breast radiotherapy. Adequate imaging of the GBT is necessary and will be assessed between MRI and CT modalities. GBT visualisation is acknowledged to be qualitatively superior on Magnetic Resonance Image (MRI) compared to Computed Tomography (CT), the current radiotherapy imaging standard, however this has not been quantitatively assessed...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047833/th-cd-bra-06-magnetic-field-effects-on-gafchromic-film-response-in-mr-igrt
#16
F Reynoso, A Curcuru, O Green, S Mutic, I Das, L Santanam
PURPOSE: To investigate the effects of magnetic fields in radiochromic films (RCF). Magnetokinetic changes may affect crystal orientation and polymerization within active layer of RCF, these effects are investigated in Magnetic Resonance Image-guided Radiotherapy (MR-IGRT). METHODS: Gafchromic EBT2 RCF were irradiated in a 30×30×30 cm(3) solid water phantom using a ViewRay MRIdian Co-60 MRI guided radiotherapy system (B=0.35 T). Fifteen 20.3×25.4 cm(2) EBT2 film sheets were placed at three different depths (d=0...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047787/th-ab-bra-02-automated-triplet-beam-orientation-optimization-for-mri-guided-co-60-radiotherapy
#17
D Nguyen, D Thomas, M Cao, D O'Connor, J Lamb, K Sheng
PURPOSE: MRI guided Co-60 provides daily and intrafractional MRI soft tissue imaging for improved target tracking and adaptive radiotherapy. To remedy the low output limitation, the system uses three Co-60 sources at 120° apart, but using all three sources in planning is considerably unintuitive. We automate the beam orientation optimization using column generation, and then solve a novel fluence map optimization (FMO) problem while regularizing the number of MLC segments. METHODS: Three patients-1 prostate (PRT), 1 lung (LNG), and 1 head-and-neck boost plan (H&NBoost)-were evaluated...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047732/th-cd-bra-02-3d-remote-dosimetry-for-mri-guided-radiation-therapy-a-hybrid-approach
#18
L Rankine, S Mein, J Adamovics, B Cai, A Curcuru, T Juang, D Miles, S Mutic, Y Wang, M Oldham, H Li
PURPOSE: To validate the dosimetric accuracy of a commercially available MR-IGRT system using a combination of 3D dosimetry measurements (with PRESAGE(R) radiochromic plastic and optical-CT readout) and an in-house developed GPU-accelerated PENELOPE Monte-Carlo dose calculation system. METHODS: (60) Co IMRT subject to a 0.35T lateral magnetic field has recently been commissioned in our institution following AAPM's TG-119 recommendations. We performed PRESAGE(R) sensitivity studies in 4ml cuvettes to verify linearity, MR-compatibility, and energy-independence...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047704/su-g-jep2-05-dose-effects-of-a-1-5t-magnetic-field-on-air-tissue-and-lung-tissue-interfaces-in-mri-guided-radiotherapy
#19
Xinfeng Chen, Phillip Prior, Guangpei Chen, Christopher Schultz, X Allen Li
PURPOSE: The purpose of the study is to investigate the dose effects of electron-return-effect (ERE) at air-tissue and lung-tissue interfaces under a 1.5T transverse-magnetic-field (TMF). METHODS: IMRT and VMAT plans for representative pancreas, lung, breast and head & neck (H&N) cases were generated following clinical dose volume (DV) criteria. The air-cavity walls, as well as the lung wall, were delineated to examine the ERE. In each case, the original plan generated without TMF is compared with the reconstructed plan (generated by recalculating the original plan with the presence of TMF) and the optimized plan (generated by a full optimization with TMF), using a variety of DV parameters, including V100%, D95% and dose heterogeneity index for PTV, Dmax, and D1cc for OARs (organs at risk) and tissue interface...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047701/th-ab-bra-09-stability-analysis-of-a-novel-dose-calculation-algorithm-for-mri-guided-radiotherapy
#20
O Zelyak, B Fallone, J St Aubin
PURPOSE: To determine the iterative deterministic solution stability of the Linear Boltzmann Transport Equation (LBTE) in the presence of magnetic fields. METHODS: The LBTE with magnetic fields under investigation is derived using a discrete ordinates approach. The stability analysis is performed using analytical and numerical methods. Analytically, the spectral Fourier analysis is used to obtain the convergence rate of the source iteration procedures based on finding the largest eigenvalue of the iterative operator...
June 2016: Medical Physics
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