Abstract:
:In the last 30 years, thousands of basic or clinical studies have been devoted to atherosclerosis or to the problem of restenosis after angioplasty. In these studies, axial stresses in the vessel wall have received practically no attention, contrary to circumferential stress and purely biological aspects. Based on a recent article describing how arterial stenoses can induce a considerable increase in axial wall stress during flow systole in the region immediately proximal to the stenosis entrance, we have used a simple (theoretical) spring model and data available in the literature on the mechanical properties of arteries to investigate the relative wall elongations (axial strains) resulting from the systolic increases in axial stress generated by the stenosis. The model shows that high axial wall strains are tightly limited to the stenosis entrance if the axial wall forces generating the supplementary stress are strongly absorbed by the tissues surrounding the vessel. Inversely, if this absorption is weak, the zone of high strains extends over a longer vessel segment upstream of the stenosis entrance. The maximum strain value, which is always situated at the stenosis entrance, appears to be relatively independent of the presence or absence of surrounding tissues. The simulation also shows that in a 3 mm coronary artery presenting a 75% diameter stenosis, the axial strain at the stenosis entrance can exceed 10% at peak flow, depending on the respective axial elasticities of vessel wall and surrounding tissues. In a more severe stenosis, or in case of a pathologically high systolic pressure, the maximum strain value might even exceed 20%. Since abnormal axial strains have been shown to induce abnormal biological processes in smooth muscle cells cultures, it is quite conceivable that such axial strains are deleterious, at least in arterial segments whose length normally does not vary.
journal_name
Med Physjournal_title
Medical physicsauthors
Doriot PA,Dorsaz PAdoi
10.1118/1.1844432subject
Has Abstractpub_date
2005-02-01 00:00:00pages
360-8issue
2eissn
0094-2405issn
2473-4209journal_volume
32pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract:PURPOSE:Using a new linear accelerator with high dose rate (800 MU/min), fast MLC motions (5.0 cm/s), fast gantry rotation (15 s/rotation), and 1 cm wide MLCs, we aimed to quantify the effects of complexity, arc number, and fractionation on interplay for breast and lung treatments under target motion. METHODS:To study...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12899
更新日期:2018-06-01 00:00:00
abstract::Heating rate (HR) patterns in cylindrical structures were studied with inhomogeneous limb phantoms. These phantoms, arm and thigh models consisting of fat, bone, and muscle material, were heated with Clini-Therm L, M, and MS applicators at 915 MHz. The thigh model is 18 cm in diameter with 2.65-cm-thick fat on the out...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596627
更新日期:1991-11-01 00:00:00
abstract:PURPOSE:To present the results of a patient dose evaluation program in pediatric cardiology and propose local diagnostic reference levels (DRLs) for different types of procedure and age range, in addition to suggesting approaches to correlate patient dose values with patient weight. This study was the first conducted i...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4905116
更新日期:2015-02-01 00:00:00
abstract:PURPOSE:Temporal subtraction is used to detect the interval change in chest radiographs and aid radiologists in patient diagnosis. This method registers two temporally different images by geometrically warping the lung region, or "lung mask," of a previous radiographic image to align with the current image. The gray le...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3259712
更新日期:2009-12-01 00:00:00
abstract:PURPOSE:The purpose of this study was to assess, using an anthropomorphic digital phantom, the accuracy of algorithms in registering precontrast and contrast-enhanced computed tomography (CT) chest images for generation of iodine maps of the pulmonary parenchyma via temporal subtraction. MATERIALS AND METHODS:The XCAT...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13496
更新日期:2019-05-01 00:00:00
abstract:PURPOSE:TransitQA is an innovative method for Tomotherapy transit dosimetry using the on-board detector (OBD). Our previously published model for Tomotherapy treatment plan verification (AirQA) has been enhanced to take into account patient and couch transmission. AirQA estimates the OBD signal during irradiation with ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12672
更新日期:2018-01-01 00:00:00
abstract::The purpose of this study is to understand the effect of pitch on raw data interpolation in multislice spiral/helical computed tomography (CT) and provide guidelines for scanner design and protocol optimization. Multislice spiral CT is mainly characterized by the three parameters: the number of detector arrays, the de...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598804
更新日期:1999-12-01 00:00:00
abstract::It is known that motion of an object imaged by magnetic resonance imaging leads to errors and artifacts in the image. This effect is especially important when a pulse sequence with long echo time (TE) and long TR is used to provide T2-weighted images. We have modified the usual spin warp imaging pulse sequence in a wa...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596026
更新日期:1987-07-01 00:00:00
abstract::The absorbed dose values determined with the Exradin and PTW-Markus plane-parallel chambers were compared to the values obtained with the ferrous sulphate dosimetry for a number of the Philips SL25 and the Therac 20 electron beams. For the plane-parallel chambers, the cavity-gas calibration factor Ngaspp, was derived ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597800
更新日期:1996-03-01 00:00:00
abstract:PURPOSE:Liver segmentation is an important prerequisite for the assessment of liver cancer treatment options like tumor resection, image-guided radiation therapy (IGRT), radiofrequency ablation, etc. The purpose of this work was to evaluate a new approach for liver segmentation. METHODS:A graph cuts segmentation metho...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3682171
更新日期:2012-03-01 00:00:00
abstract:PURPOSE:Prostate cancer ranks as one of the most common malignancies and currently represents the second leading cancer-specific cause of death in men. The current use of single modality transrectal ultrasound (TRUS) for biopsy guidance has a limited sensitivity and specificity for accurately identifying cancerous lesi...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4803498
更新日期:2013-06-01 00:00:00
abstract:PURPOSE:The use of 4D computed tomography (4D-CT) of the lung is important in lung cancer radiotherapy for tumor localization and treatment planning. Sometimes, dense sampling is not acquired along the superior-inferior direction. This disadvantage results in an interslice thickness that is much greater than in-plane v...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4899185
更新日期:2014-11-01 00:00:00
abstract:PURPOSE:Currently, no 3D or 4D volumetric x-ray imaging techniques are available for intrafraction verification of target position during actual treatment delivery or in-between treatment beams, which is critical for stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) treatments. This study a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4861820
更新日期:2014-02-01 00:00:00
abstract::Teletherapy with high linear energy transfer radiations (LET), perhaps more than with low LET types, requires careful beam collimation to limit effects to normal structures. Intensity modulated techniques may also hold promise in this regard. Accordingly, a remote computer-controlled, high-resolution multileaf collima...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2760026
更新日期:2007-09-01 00:00:00
abstract::Interchange or transfer of radiographic techniques through measurement of penetration quality is discussed. The usefulness of this achievement is verified using an aluminum step wedge. Also, the procedure described provides a method for performance evaluation of kVp compensation on diagnostic x-ray installations. ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.594156
更新日期:1975-01-01 00:00:00
abstract::Stereotactic Body Radiation Therapy (SBRT) is being increasingly used in the radiation oncology community to treat tumors in extra-cranial sites such as spine, lung, liver, pancreas and prostate. There are well established RTOG protocols (e.g. RTOG 0631 for spine, RTOG 0813 and 0915 for lung and RTOG 0438 for liver) t...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4736142
更新日期:2012-06-01 00:00:00
abstract::In this paper, the consistency of kilovoltage (tube potentials between 40 and 300 kV) x-ray beam dosimetry using the "in-air" method and the in-phantom measurement has been studied. The procedures for the measurement of the central-axis depth-dose curve, which serve as a link between the dose at the reference depth to...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598448
更新日期:1998-12-01 00:00:00
abstract:PURPOSE:The biologically effective dose (BED) of temporary brachytherapy treatments is a function of both chosen radionuclide (R) and implant duration (T). This study endeavored to evaluate BED delivered to the tumor volume and surrounding ocular structures as a function of plaque position (P), prescription dose, R, an...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735548
更新日期:2012-06-01 00:00:00
abstract::The purpose of this study was to investigate the effect of z overscanning on eye lens dose and effective dose received by pediatric patients undergoing head CT examinations. A pediatric patient study was carried out to obtain the exposure parameters and data regarding the eye lens position with respect to imaged volum...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2207212
更新日期:2006-07-01 00:00:00
abstract::Francis Bacon, who with Rene Decartes laid the intellectual foundations for Western science in the seventeenth century, asserted that the purpose of all knowledge is "action in the production of works for ... the relief of man's estate." We assess briefly several aspects of a few of the current efforts directed to the...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1555493
更新日期:2003-04-01 00:00:00
abstract:PURPOSE:Real-time sub-millimeter head motion compensation during frameless SRS delivery has the potential to achieve the accuracy of frame-based SRS while being significantly less invasive. Previously, we demonstrated real-time 6D head motion monitoring using an optical camera, however, at the time we were limited to o...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4734995
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:To build a statistical model to quantitatively correlate the anatomic features of structures and the corresponding dose-volume histogram (DVH) of head and neck (HN) Tomotherapy (Tomo) plans. To study if the model built upon one intensity modulated radiation therapy (IMRT) technique (such as conventional Linac) ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4828788
更新日期:2013-12-01 00:00:00
abstract::In this work, the authors have evaluated ten different ionization chambers for the relative dosimetry of kilovoltage x-ray beams in the energy range of 50-280 kVp. Percentage depth doses in water and relative detector response (in Solid Water and in air) were measured for each of the x-ray beams studied using a number...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3183820
更新日期:2009-09-01 00:00:00
abstract::Deionized water is commonly used to couple microwave applicators to the patient surface in the administration of local hyperthermia. Profiles of the specific absorption rate (SAR) at 1-cm depth show that deionized water coupling significantly distorts the SAR distributions of the Clini-Therm 915-MHz 10 X 10 and 15 X 1...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595881
更新日期:1986-05-01 00:00:00
abstract::Extensive information has been made available relative to the physical aspects necessary for calculation of radiation absorbed dose from radiopharmaceuticals. A similar data base for the biological factors involved in these calculations has not been documented as thoroughly. The authors present an extensive literature...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.594679
更新日期:1980-05-01 00:00:00
abstract:PURPOSE:A dosimetric system formed by Gafchromic EBT2 radiochromic film and Epson Expression 10000XL flatbed scanner was commissioned for dosimetry. In this paper, several open questions concerning the commissioning of radiochromic films for dosimetry were addressed: (a) is it possible to employ this dosimetric system ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4772075
更新日期:2013-01-01 00:00:00
abstract:PURPOSE:To evaluate a commercial volumetric modulated arc therapy (VMAT), using multiple noncoplanar arcs, for linac-based cranial radiosurgery, as well as evaluate the combined accuracy of the VMAT dose calculations and delivery. METHODS:Twelve patients with cranial lesions of variable size (0.1-29 cc) and two multip...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3641874
更新日期:2011-11-01 00:00:00
abstract:PURPOSE:To obtain on-treatment volumetric patient anatomy during respiratory gated volumetric modulated arc therapy (VMAT). METHODS:On-board imaging device integrated with Linacs offers a viable tool for obtaining patient anatomy during radiation treatment delivery. In this study, the authors acquired beam-level kV im...
journal_title:Medical physics
pub_type: 信件
doi:10.1118/1.4794925
更新日期:2013-04-01 00:00:00
abstract:PURPOSE:This study aims to investigate carotid plaque calcification (CPC) using two-dimensional (2D) and 3D ultrashort echo time (UTE) magnetic resonance imaging (MRI) sequences and compare T1, T2*, water concentration, and bone mineral density (BMD) of CPC with those of cortical bone. METHODS:Twelve carotid plaque sp...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4819944
更新日期:2013-10-01 00:00:00
abstract:PURPOSE:To investigate the accuracy of output factor measurements using a commercial (Exradin W1, SI) and a prototype, "in-house" developed, plastic scintillation dosimeter (PSD) in small photon fields. METHODS:Repetitive detector-specific output factor OFdet measurements were performed in water (parallel to the CAX) ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12064
更新日期:2017-02-01 00:00:00