Local hydrogen clearance as a method for the measurement of capillary blood flow.

abstract：:The purpose of this work was to use Monte Carlo simulations to verify the accuracy of the dose distributions from a commercial treatment planning optimization system (Corvus, Nomos Corp., Sewickley, PA) for intensity-modulated radiotherapy (IMRT). A Monte Carlo treatment planning system has been implemented clinically...

journal_title：Physics in medicine and biology

authors： Ma CM,Pawlicki T,Jiang SB,Li JS,Deng J,Mok E,Kapur A,Xing L,Ma L,Boyer AL

更新日期：2000-09-01 00:00:00

abstract：:A number of heating sources are available for minimally invasive thermal therapy of tumours. The purpose of this work was to compare, theoretically, the heating characteristics of interstitial microwave, laser and ultrasound sources in three tissue sites: breast, brain and liver. Using a numerical method, the heating ...

journal_title：Physics in medicine and biology

authors： Skinner MG,Iizuka MN,Kolios MC,Sherar MD

更新日期：1998-12-01 00:00:00

abstract：:Kinetic parameters are commonly estimated from dynamically acquired nuclear medicine data by first reconstructing a dynamic sequence of images and subsequently fitting the parameters to time-activity curves generated from regions of interest overlaid upon the image sequence. Biased estimates can result from images rec...

journal_title：Physics in medicine and biology

authors： Huesman RH,Reutter BW,Zeng GL,Gullberg GT

更新日期：1998-04-01 00:00:00

abstract：:The goal of this study was to assess the impact of set-up uncertainty on compliance with the objectives and constraints of an intensity modulated radiation therapy protocol for early stage cancer of the oropharynx. As the convolution approach to the quantitative study of set-up uncertainties cannot accommodate either ...

journal_title：Physics in medicine and biology

authors： Ploquin N,Song W,Lau H,Dunscombe P

更新日期：2005-08-07 00:00:00

abstract：:The purpose of this study is to evaluate a new method to improve performance of computer-aided detection (CAD) schemes of screening mammograms with two approaches. In the first approach, we developed a new case based CAD scheme using a set of optimally selected global mammographic density, texture, spiculation, and st...

journal_title：Physics in medicine and biology

authors： Tan M,Aghaei F,Wang Y,Zheng B

更新日期：2017-01-21 00:00:00

abstract：:Online proton range/dose verification based on measurements of proton-induced positron emitters is a promising strategy for quality assurance in proton therapy. Because of the nonlinear correlation between the dose distribution and the activity distribution of positron emitters, we aim to establish their relationship ...

journal_title：Physics in medicine and biology

authors： Liu C,Li Z,Hu W,Xing L,Peng H

更新日期：2019-09-04 00:00:00

abstract：:K line x-ray fluorescence (KXRF) measurements of bone lead have emerged as a promising new biological marker of internal lead dose in epidemiological studies. Some disagreements exist, however, over the analysis of data at low levels of bone lead concentration. In this study, we performed 30 serial measurements on eac...

journal_title：Physics in medicine and biology

authors： Kim R,Aro A,Rotnitzky A,Amarasiriwardena C,Hu H

更新日期：1995-09-01 00:00:00

abstract：:X-ray scatter is a significant problem in cone-beam computed tomography when thicker objects and larger cone angles are used, as scattered radiation can lead to reduced contrast and CT number inaccuracy. Advances have been made in x-ray computed tomography (CT) by incorporating a high quality prior image into the imag...

journal_title：Physics in medicine and biology

authors： Brunner S,Nett BE,Tolakanahalli R,Chen GH

更新日期：2011-02-21 00:00:00

abstract：:The total ionisation produced by ions stopped in nitrogen, methane and carbon dioxide has been measured in the energy range 25-375 keV using a chamber described previously. The chamber was operated alternately as a proportional counter and as an ionisation chamber to measure respectively the particle rate and the tota...

journal_title：Physics in medicine and biology

authors： Nguyen VD,Chemtob M,Chary J,Posny F,Parmentier N

更新日期：1980-05-01 00:00:00

abstract：:A method of computing theoretical X-ray spectra in the range 30-150 kV is presented. The theoretical spectra are compared with constant potential, high resolution spectra from a tungsten target measured with a Ge(Li) detector, for a range of target angles, tube voltage and filtrations. Above 100 kV the spectra were al...

journal_title：Physics in medicine and biology

authors： Birch R,Marshall M

更新日期：1979-05-01 00:00:00

abstract：:Over the last decade, the performance of benchtop x-ray fluorescence computed tomography (XFCT) systems has been significantly enhanced through hardware and software optimizations. Recent studies have indicated the need of energy-resolving pixelated/array detectors in the x-ray detection component to further improve t...

journal_title：Physics in medicine and biology

authors： Moktan H,Ahmed MF,Jayarathna S,Deng L,Cho SH

更新日期：2020-08-31 00:00:00

abstract：:Light propagation in a turbid medium is considered using the linear transport equation. The existence of a diffusion length is proved for the Henyey-Greenstein scattering kernel for all absorption ratios. Numerical methods are given that allow accurate computation of the diffusion coefficient quite easily. ...

journal_title：Physics in medicine and biology

authors： Sahni DC,Dahl EB,Sjöstrand NG

更新日期：2003-12-07 00:00:00

abstract：:A classical trajectory model has been used to predict total cross sections of single and double ionizing processes (including capture processes) for several ion-biological molecule collisional systems in the intermediate and high energy range. In this work, the systems studied are water, adenine or cytosine targets io...

journal_title：Physics in medicine and biology

authors： Abbas I,Champion C,Zarour B,Lasri B,Hanssen J

更新日期：2008-02-21 00:00:00

abstract：:The radiofrequency dielectric behaviour of packed human erythrocytes has been investigated in normal haemoglobins F and AA and also abnormal haemoglobins homozygous SS and heterozygous AS. Dielectric measurements were made in tightly packed blood cells at an average room temperature of 26.5 +/- 0.5 degrees C in the fr...

journal_title：Physics in medicine and biology

authors： Laogun AA,Ajayi NO,Okafor LO,Osamo NO

更新日期：1983-04-01 00:00:00

abstract：:Absorbed dose values were determined under the reference conditions in a phantom irradiated by high-energy photon beams with quality varying between 60Co gamma rays and 25 MV X-rays, using four commonly employed types of ionisation chamber. The ionisation chamber readings were converted to absorbed dose values applyin...

journal_title：Physics in medicine and biology

authors： Mijnheer BJ,Wittkämper FW

更新日期：1986-04-01 00:00:00

abstract：:Detectors used for positron emission tomography (PET) provide fast, randomly distributed signals that need to be digitized for further processing. One possibility is to sample the signals at the peak initiated by a trigger from a constant fraction discriminator (CFD). For PET detectors, simultaneous acquisition of man...

journal_title：Physics in medicine and biology

authors： Judenhofer MS,Pichler BJ,Cherry SR

更新日期：2005-01-07 00:00:00

abstract：:We show that it is possible to translate an intensity modulated radiation therapy (IMRT) treatment plan and deliver it as a single arc. This technique is referred to in this paper as aperture modulation arc therapy (AMAT). During this arc, the MLC leaves do not conform to the projection of the target PTV and the machi...

journal_title：Physics in medicine and biology

authors： Crooks SM,Wu X,Takita C,Watzich M,Xing L

更新日期：2003-05-21 00:00:00

abstract：:The inadequate visibility of microcalcifications-small calcium deposits that cue radiologists to early stages of cancer-is a major limitation in current designs of dedicated breast computed tomography (bCT). This limitation has previously been attributed to the constituent components, spatial resolution, and utilized ...

journal_title：Physics in medicine and biology

authors： Ghazi P

更新日期：2020-12-04 00:00:00

abstract：:Radiochromic leuco crystal violet (LCV) micelle gel dosimeters are promising three-dimensional radiation dosimeters because of their spatial stability and suitability for optical readout. The effects of surfactant type and surfactant concentration on dose sensitivity of LCV micelle gels are tested, demonstrating that ...

journal_title：Physics in medicine and biology

authors： Nasr AT,Alexander K,Schreiner LJ,McAuley KB

更新日期：2015-06-21 00:00:00

abstract：:Simultaneous dual-radionuclide myocardial perfusion/innervation SPECT imaging can provide important information about the mismatch between scar tissue and denervated regions. The Siemens IQ-SPECT system developed for cardiac imaging uses a multifocal SMARTZOOM collimator to achieve a four-fold sensitivity for the card...

journal_title：Physics in medicine and biology

authors： Du Y,Bhattacharya M,Frey EC

更新日期：2014-06-07 00:00:00

abstract：:The aim of this work was to evaluate the accuracy of dose predicted in heterogeneous media by a pencil beam (PB), a collapsed cone (CC) and a Monte Carlo (MC) algorithm. For this purpose, a simple multi-layer phantom composed of Styrofoam and white polystyrene was irradiated with 10 x 10 cm2 as well as 20 x 20 cm2 ope...

journal_title：Physics in medicine and biology

authors： Krieger T,Sauer OA

更新日期：2005-03-07 00:00:00

abstract：:This paper describes end-to-end test procedures as the last fundamental step of medical commissioning before starting clinical operation of the MedAustron synchrotron-based pencil beam scanning (PBS) therapy facility with protons. One in-house homogeneous phantom and two anthropomorphic heterogeneous (head and pelvis)...

journal_title：Physics in medicine and biology

authors： Carlino A,Gouldstone C,Kragl G,Traneus E,Marrale M,Vatnitsky S,Stock M,Palmans H

更新日期：2018-02-26 00:00:00

abstract：:Boundary element methods (BEM) are used for forward computation of bioelectromagnetic fields in multi-compartment volume conductor models. Most BEM approaches assume that each compartment is in contact with at most one external compartment. In this work, I present a general surface integral equation and BEM discretiza...

journal_title：Physics in medicine and biology

authors： Stenroos M

更新日期：2016-11-21 00:00:00

abstract：:We present a new method for automated characterization of atherosclerotic plaque composition in ex vivo MRI. It uses MRI intensities as well as four other types of features: smoothed, gradient magnitude and Laplacian images at several scales, and the distances to the lumen and outer vessel wall. The ground truth for f...

journal_title：Physics in medicine and biology

authors： van Engelen A,Niessen WJ,Klein S,Groen HC,Verhagen HJ,Wentzel JJ,van der Lugt A,de Bruijne M

更新日期：2012-01-07 00:00:00

abstract：:For the first time, three-dimensional images of the newborn infant brain have been generated using measurements of transmitted light. A 32-channel time-resolved imaging system was employed, and data were acquired using custom-made helmets which couple source fibres and detector bundles to the infant head. Images have ...

journal_title：Physics in medicine and biology

authors： Hebden JC,Gibson A,Yusof RM,Everdell N,Hillman EM,Delpy DT,Arridge SR,Austin T,Meek JH,Wyatt JS

更新日期：2002-12-07 00:00:00

abstract：:The treatment delivery time of intensity-modulated radiation therapy (IMRT) with a multileaf collimator (MLC) is generally longer than that of conventional radiotherapy. In theory, removing the flattening filter from the treatment head may reduce the beam-on time by enhancing the output dose rate, and then reduce the ...

journal_title：Physics in medicine and biology

authors： Fu W,Dai J,Hu Y,Han D,Song Y

更新日期：2004-04-21 00:00:00

abstract：:An inverse radiation treatment planning algorithm for Sensus Healthcare's SculpturaTM electronic brachytherapy system has been designed. The algorithm makes use of simulated annealing to optimize the conformation number of the treatment plan. The highly anisotropic dose distributions produced by the SculpturaTM x-ray ...

journal_title：Physics in medicine and biology

authors： Badali DS,Vainer Y,Ellenor CW,Mitchell CR,Fishman K,Soro N,Price R,Funk T

更新日期：2021-01-11 00:00:00

abstract：:Current dosimetry protocols (AAPM, IAEA, DIN) recommend the use of parallel-plate ionization chambers for the measurement of absorbed dose-to-water in clinical electron beams. For well-guarded plane-parallel chambers, it is assumed that the perturbation correction pQ is unity for all electron energies. In this study, ...

journal_title：Physics in medicine and biology

authors： Zink K,Wulff J

更新日期：2008-03-21 00:00:00

abstract：:The aim of the present work was to implement the kinetics of cisplatin into a previously developed tumour growth model and to simulate the combined cisplatin-radiotherapy treatment with the emphasis on time sequencing and scheduling of drug and radiation. An investigation into whether the effect of cisplatin-radiation...

journal_title：Physics in medicine and biology

authors： Marcu L,Bezak E,Olver I

更新日期：2006-08-07 00:00:00

abstract：:Depth-dose distributions were calculated for thermal and epithermal neutron fluence and capture gamma ray dose rates using a two-dimensional neutron-coupled gamma-ray transport code (DOT 3.5) for gadolinium neutron capture therapy. The results show that (i) a capture gamma-ray dose rate of 10 Gy h-1 was obtained with ...

journal_title：Physics in medicine and biology

authors： Matsumoto T

更新日期：1992-01-01 00:00:00