Abstract:
PURPOSE:Arterial distensibility is a marker that can measure vessel wall functional and structural changes resulting from atherosclerosis with applications including estimation of mechanical properties of the wall. We sought to assess the feasibility of using magnetic resonance imaging (MRI) to include wall distensibility in the characterization of atherosclerotic carotid arteries and to analyze the relationship between distensibility and morphological and compositional plaque features. METHODS:Five healthy volunteers were imaged with a multiple-slice CINE MR sequence twice, within 24 h, to determine the interscan reproducibility of distensibility measurements. Twenty-one subjects with >15% carotid stenosis and the five healthy volunteers were imaged using a multicontrast carotid MRI protocol to characterize arterial wall morphology and composition. Normalized wall index (wall area∕total vessel area), maximum wall thickness and, if present, percentages of wall area occupied by calcification and lipid-rich necrotic core were determined. A multiple-slice CINE MR sequence was added to the multicontrast protocol to measure the distensibility coefficient (DC) at several locations spanning the bifurcation. The intraclass correlation coefficient (ICC) and the coefficient of variation were used to assess the reproducibility of DC measurements made on the healthy subjects. The DC was compared between arterial segments and between the healthy and diseased groups. Furthermore, within the diseased group, DC was correlated to plaque morphology and composition at each location as well as that averaged over the plaque. RESULTS:Distensibility measurements were highly reproducible: ICC (95% confidence interval) was 0.998 (0.96-1.0) for the common carotid segment and 0.990 (0.92-1.0) for the internal carotid segment. In healthy volunteers, we found significantly higher distensibility in the common segment of the carotid artery compared to the internal carotid segment (mean ± SD = 4.56 ± 1.02 versus 3.56 ± 1.32 × 10(-5)∕Pa; p < 0.05). However, no segmental differences were seen in the diseased group (3.25 ± 1.84 versus 3.26 ± 1.60 × 10(-5)∕Pa; p = 0.607). Location-to-location changes in DC were not found to correlate to changes in the local plaque morphology or composition nor were average DC found to be associated with aggregate plaque features. CONCLUSIONS:These results demonstrate the feasibility of MRI to measure distensibility in the carotid artery and to presumably detect changes in distensibility due to age and∕or disease. The results suggest that the effect of atherosclerosis on local distensibility may not strongly depend upon the specific underlying plaque features in mild to moderate stenotic carotid lesions though more diffuse or nonlocal changes in arterial distensibility could not be ruled out.
journal_name
Med Physjournal_title
Medical physicsauthors
Canton G,Hippe DS,Sun J,Underhill HR,Kerwin WS,Tang D,Yuan Cdoi
10.1118/1.4754302subject
Has Abstractpub_date
2012-10-01 00:00:00pages
6247-53issue
10eissn
0094-2405issn
2473-4209journal_volume
39pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract:PURPOSE:Optically stimulated luminescence (OSL) dosimetry has been recently introduced in radiation therapy as a potential alternative to the thermoluminescent dosimeter (TLD) system. The aim of this study was to investigate the feasibility of using OSL point dosimeters in the energy range used in diagnostic imaging. ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3602456
更新日期:2011-07-01 00:00:00
abstract::When treating prostate cancer using high dose rate (HDR) brachytherapy, overdosing the rectal wall may lead to post-treatment rectal complications. An area of concern is related to how the rectal wall dose is calculated by treatment planning systems (TPSs). TPSs are used to calculate the dose delivered to the rectal w...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3031111
更新日期:2009-01-01 00:00:00
abstract:PURPOSE:The presence of respiratory motion during radiation treatment leads to degradation of the expected dose distribution, both for target coverage and healthy tissue sparing, particularly for techniques like pencil beam scanning proton therapy which have dynamic delivery systems. While tools exist to estimate this ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13182
更新日期:2018-11-01 00:00:00
abstract:PURPOSE:In our institute, the MatriXX has been used for IMRT, VMAT and dynamic arc QA. However, the small fields (<3cm) shaped by HDMLC for SRS dynamic arc (DA) present QA measurement issues when using the MatriXX due to its limited resolution (7.6 mm). A recently available portal dosimetry (PD) software tool in Eclips...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735167
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:To compare optimization characteristics, plan quality, and treatment delivery efficiency between total marrow irradiation (TMI) plans using the new TomoTherapy graphic processing unit (GPU) based dose engine and CPU/cluster based dose engine. METHODS:Five TMI plans created on an anthropomorphic phantom were op...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4810936
更新日期:2013-07-01 00:00:00
abstract::The physical factors that govern 2D and 3D imaging performance may be understood from quantitative analysis of the spatial-frequency-dependent signal and noise transfer characteristics [e.g., modulation transfer function (MTF), noise-power spectrum (NPS), detective quantum efficiency (DQE), and noise-equivalent quanta...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3002414
更新日期:2008-12-01 00:00:00
abstract::An important aspect of the intensity modulated radiotherapy (IMRT) process is that of optimizing the beam intensity profiles. Most such methods use a comparison between the defined dose distribution (including prescription dose and dose limits for critical structures) and the current distribution. The comparison may i...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1428756
更新日期:2002-01-01 00:00:00
abstract:PURPOSE:Previous studies have shown atlas-based segmentation using a single best matched (SBM) atlas subject can significantly reduce contouring time. A new multi-atlas approach has been shown to provide greater accuracy than SBM for cancer of the head and neck. The goal of this study was to evaluate the multi-atlas te...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4734942
更新日期:2012-06-01 00:00:00
abstract::Coherent scattering of x-ray photons leads to the phenomenon of x-ray diffraction, which is widely used for determining atomic structure in materials science. A technique [x-ray diffraction computed tomography (CT)] is described, analogous to conventional CT, in which the x-ray diffraction properties of a stack of two...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596063
更新日期:1987-07-01 00:00:00
abstract:PURPOSE:This paper describes the clinical implementation and medical commissioning of the MedAustron Particle Therapy Accelerator (MAPTA) for non-isocentric scanned proton beam treatments. METHODS:Medical physics involvement during technical commissioning work is presented. Acceptance testing procedures, including adv...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13928
更新日期:2020-02-01 00:00:00
abstract:PURPOSE:To quickly and automatically propagate organ contours from pretreatment to fraction images in magnetic resonance (MR)-guided prostate external-beam radiotherapy. METHODS:Five prostate cancer patients underwent 20 fractions of image-guided external-beam radiotherapy on a 1.5 T MR-Linac system. For each patient,...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13994
更新日期:2020-03-01 00:00:00
abstract::The proper evaluation of the accuracy of a new computer program for radiation-therapy dosimetry requires consideration of both the mathematical algorithm used in the program and the performance required in clinical applications. As an example, our evaluation of the irregular-fields dosimetry program currently marketed...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.594344
更新日期:1977-11-01 00:00:00
abstract:PURPOSE:To introduce a novel laser-based optical-CT scanner for the readout of three-dimensional (3D) radiation dosimeters. METHODS:The scanner employs a diode laser, a cylindrical lens, a motorized linear rail, a rotation stage, and a charge-coupled device camera. The scanner operates in a translate-rotate fashion an...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3538924
更新日期:2011-02-01 00:00:00
abstract::The paper presents a theoretical derivation of the photon fluence simulation efficiency in photon beam treatment head simulations without and with bremsstrahlung splitting. The expressions obtained provide a rigorous explanation of the efficiency dependence on scoring zone size and splitting number and explain the lar...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1943808
更新日期:2005-07-01 00:00:00
abstract::Treatment planning for brachytherapy requires the acquisition of geometrical information of the implant applicator and the patient anatomy. This is typically done using a simulator or a computed tomography scanner. In this study, we present a different method by which orthogonal images from a C-arm fluoroscopic machin...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1598851
更新日期:2003-09-01 00:00:00
abstract::Treatment simulation is usually performed with a conventional simulator using kV X-rays or with a computed tomography (CT) simulator before the treatment course begins. The purpose is to verify patient setup under the same conditions as for treatment planning. Systematic (preparation) setup errors can be introduced by...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2727299
更新日期:2007-05-01 00:00:00
abstract:PURPOSE:The absolute dose rate of the Imaging and Medical Beamline (IMBL) on the Australian Synchrotron was measured with a graphite calorimeter. The calorimetry results were compared to measurements from the existing free-air chamber, to provide a robust determination of the absolute dose in the synchrotron beam and p...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4870387
更新日期:2014-05-01 00:00:00
abstract:PURPOSE:Measuring and incorporating a scanner-specific point spread function (PSF) within image reconstruction has been shown to improve spatial resolution in PET. However, due to the short half-life of clinically used isotopes, other long-lived isotopes not used in clinical practice are used to perform the PSF measure...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4870985
更新日期:2014-05-01 00:00:00
abstract:PURPOSE:To estimate organ and effective radiation doses due to backscatter security scanners using Monte Carlo simulations and a voxelized phantom set. METHODS:Voxelized phantoms of male and female adults and children were used with the GEANT4 toolkit to simulate a backscatter security scan. The backscatter system was...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4718680
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:To provide a cascaded-systems framework based on the noise-power spectrum (NPS), modulation transfer function (MTF), and noise-equivalent number of quanta (NEQ) for quantitative evaluation of differential phase-contrast imaging (Talbot interferometry) in relation to conventional absorption contrast under equal-...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4739195
更新日期:2012-09-01 00:00:00
abstract::A computer dose model for a low energy gamma-emitting stent in a heterogeneous medium is described. The method is based on the Sievert model which is adapted to the dose-point-kernel (DPK) model to compute the dose distribution about filtered gamma sources (Sievert-DPK model). The new gamma stent model can take into a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1380214
更新日期:2001-07-01 00:00:00
abstract:PURPOSE:Two diodes which do not require correction factors for small field relative output measurements are designed and validated using experimental methodology. This was achieved by adding an air layer above the active volume of the diode detectors, which canceled out the increase in response of the diodes in small f...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4894728
更新日期:2014-10-01 00:00:00
abstract:OBJECTIVE:To develop an anthropomorphic, deformable and multimodal pelvis phantom with positron emission tomography extension for radiotherapy (ADAM PETer). METHODS:The design of ADAM PETer was based on our previous pelvis phantom (ADAM) and extended for compatibility with PET and use in 3T magnetic resonance imaging ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14597
更新日期:2020-11-18 00:00:00
abstract:PURPOSE:To study the impact of target geometrical and linac operational parameters, such as target material and thickness, electron beam size, repetition rate, and mean current on the ability of the radiotherapy treatment head to deliver high-dose-rate x-ray irradiation in the context of novel linear accelerators capab...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12615
更新日期:2017-12-01 00:00:00
abstract:PURPOSE:Real-time adaptive planning and treatment has been infeasible due in part to its high computational complexity. There have been many recent efforts to utilize graphics processing units (GPUs) to accelerate the computational performance and dose accuracy in radiation therapy. Data structure and memory access pat...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4895822
更新日期:2014-10-01 00:00:00
abstract:PURPOSE:Adequate evaluation of the results from multi-institutional trials involving light ion beam treatments requires consideration of the planning margins applied to both targets and organs at risk. A major uncertainty that affects the size of these margins is the conversion of x ray computed tomography numbers (XCT...
journal_title:Medical physics
pub_type: 杂志文章,多中心研究
doi:10.1118/1.4870956
更新日期:2014-06-01 00:00:00
abstract:PURPOSE:To develop a novel aperture-based algorithm for volumetric modulated are therapy (VMAT) treatment plan optimization with high quality and high efficiency. METHODS:The VMAT optimization problem is formulated as a large-scale convex programming problem solved by a column generation approach. The authors consider...
journal_title:Medical physics
pub_type: 信件
doi:10.1118/1.3491675
更新日期:2010-11-01 00:00:00
abstract::Manganese (Mn) is an essential nutrient for growth and development. Unfortunately, overexposure can lead to neurological damage, which is manifested as a movement disorder marked by tremors. Preclinical symptoms have been found in populations occupationally exposed to the element, and it is suggested that in late stag...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1517613
更新日期:2002-11-01 00:00:00
abstract:PURPOSE:To present a noninvasive technique for directly measuring the CT bow-tie filter attenuation with a linear array x-ray detector. METHODS:A scintillator based x-ray detector of 384 pixels, 307 mm active length, and fast data acquisition (model X-Scan 0.8c4-307, Detection Technology, FI-91100 Ii, Finland) was use...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4932364
更新日期:2015-11-01 00:00:00
abstract:PURPOSE:The aim of this study was to investigate the effect of scatter and its correction on kinetic parameters in dynamic brain positron emission tomography (PET) tumor imaging. The 2-tissue compartment model was used, and two different reconstruction methods and two scatter correction (SC) schemes were investigated. ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4897610
更新日期:2014-11-01 00:00:00