Calculation of water equivalent ratios for various materials at proton energies ranging 10-500 MeV using MCNP, FLUKA, and GEANT4 Monte Carlo codes.

abstract：:In (19)F MRI oximetry, a method used to image tumour hypoxia, perfluorocarbons serve as oxygenation markers. The goal of this study is to evaluate the impact of perfluorocarbon distribution and concentration in (19)F MRI oximetry through a computer simulation. The simulation studies the correspondence between (19)F me...

journal_title：Physics in medicine and biology

authors： Baete SH,Vandecasteele J,De Deene Y

更新日期：2011-04-21 00:00:00

abstract：:The propagation of errors in quantitative biplane cineroentgenography was investigated to see which variables were the most critical. The analysis was carried out both for the propagation of root-mean-square errors and for errors as derived by a Taylor expansion of the reconstruction equations. The reconstruction is m...

journal_title：Physics in medicine and biology

authors： Smith WM,Starmer CF

更新日期：1978-07-01 00:00:00

abstract：:Crucial to all cancer therapy modalities is a strong correlation between treatment and effect. Predictability of therapy success/failure allows for the optimization of treatment protocol and aids in the decision of whether additional treatment is necessary to prevent tumour progression. This work evaluated the relatio...

journal_title：Physics in medicine and biology

authors： Hrycushko BA,Ware S,Li S,Bao A

更新日期：2011-09-07 00:00:00

abstract：:The effect of the physical state (phase) of the absorbing medium and the energy straggling of the alpha particles on the calculation of the radiation dose due to the daughter products of radon deposited in the lung have been studied in detail. The stopping power data for alpha particles in water and water vapour have ...

journal_title：Physics in medicine and biology

authors： Haque AK,Al-affan IA

更新日期：1987-08-01 00:00:00

abstract：:Microbeam radiation therapy (MRT) is a treatment approach in radiation therapy where the treatment field is spatially fractionated into arrays of a few tens of micrometre wide planar beams of unusually high peak doses separated by low dose regions of several hundred micrometre width. In preclinical studies, this treat...

journal_title：Physics in medicine and biology

authors： Debus C,Oelfke U,Bartzsch S

更新日期：2017-10-19 00:00:00

abstract：:To predict the temperature distribution during hyperthermia treatments a thermal model that accounts for the thermal effect of blood flow is mandatory. The DIscrete VAsculature (DIVA) thermal model developed at our department is able to do so; geometrically described vessels are handled individually and the remaining ...

journal_title：Physics in medicine and biology

authors： Raaymakers BW,Crezee J,Lagendijk JJ

更新日期：2000-03-01 00:00:00

abstract：:Novel x-ray medical imaging sensors, such as photon counting detectors (PCDs) and large area CCD and CMOS cameras can involve irregular and/or sparse sampling of the detector plane. Application of such detectors to CT involves undersampling that is markedly different from the commonly considered case of sparse angular...

journal_title：Physics in medicine and biology

authors： Sisniega A,Zbijewski W,Stayman JW,Xu J,Taguchi K,Fredenberg E,Lundqvist M,Siewerdsen JH

更新日期：2016-01-07 00:00:00

abstract：:The convergence rates of the fast Padé transform (FPT) and the fast Fourier transform (FFT) are compared. These two estimators are used to process a time-signal encoded at 4 T by means of one-dimensional magnetic resonance spectroscopy (MRS) for healthy human brain. It is found systematically that at any level of trun...

journal_title：Physics in medicine and biology

authors： Belkić D,Belkić K

更新日期：2005-09-21 00:00:00

abstract：:Ultrasound in the low megahertz frequency range is used by physiotherapists to treat a variety of conditions. The treatments reduce swelling, reduce pain and increase movement at joints. Ultrasound is now also beginning to be used to treat malignant tumours. The tumours are heated to temperatures between 42 degrees an...

journal_title：Physics in medicine and biology

authors： Quan KM,Shiran M,Watmough DJ

更新日期：1989-11-01 00:00:00

abstract：:Near-infrared fluorescence optical imaging has the unique opportunity of differentiating diseased lesions from normal lesions based upon environmentally indicated changes in the lifetime of a fluorescent imaging agent. In this paper, we demonstrate three-dimensional lifetime tomography using the gradient-based penalty...

journal_title：Physics in medicine and biology

authors： Roy R,Godavarty A,Sevick-Muraca EM

更新日期：2007-07-21 00:00:00

abstract：:Despite over ten years of in vitro investigations of ultrasound contrast agents, the level of understanding of their behaviour in ultrasound fields is limited. Several problems associated with these investigations, particular to the nature of contrast agents, are discussed. Using a commercial scanner the RF normalized...

journal_title：Physics in medicine and biology

authors： Sboros V,Ramnarine KV,Moran CM,Pye SD,McDicken WN

更新日期：2002-12-07 00:00:00

abstract：:The electron pencil-beam redefinition algorithm (PBRA), which is used to calculate electron beam dose distributions, assumes that the virtual source of each pencil beam is identical to that of the broad beam incident on the patient. In the present work, a virtual source specific for each pencil beam is modelled by inc...

journal_title：Physics in medicine and biology

authors： Boyd RA,Hogstrom KR,White RA,Starkschall G

更新日期：2001-11-01 00:00:00

abstract：:A 4D ordered-subsets maximum a posteriori (OSMAP) algorithm for dynamic SPECT is described which uses a temporal prior that constrains each voxel's behaviour in time to conform to a compartmental model. No a priori limitations on kinetic parameters are applied; rather, the parameter estimates evolve as the algorithm i...

journal_title：Physics in medicine and biology

authors： Kadrmas DJ,Gullberg GT

更新日期：2001-05-01 00:00:00

abstract：:In modern radiotherapy, it is vitally important to monitor the performance of all linac components including the collimation system. In this study, a simple measurement method and accurate algorithm are introduced for investigation of the secondary and tertiary collimator sag during radiotherapy arc treatments. The me...

journal_title：Physics in medicine and biology

authors： Rowshanfarzad P,Sabet M,O'Connor DJ,Greer PB

更新日期：2012-06-21 00:00:00

abstract：:This work presents an improvement of the VIPARnd ('nd' stands for 'normoxic, double', or VIP) polymer gel dosimeter. The gel composition was altered by increasing the concentration of the monomeric components, N-vinylpyrrolidone (NVP) and N,N'-methylenebisacrylamide (MBA), in co-solvent solutions. The optimal composit...

journal_title：Physics in medicine and biology

authors： Kozicki M,Jaszczak M,Maras P,Dudek M,Cłapa M

更新日期：2017-02-07 00:00:00

abstract：:The first trimester fetal ultrasound scan is important to confirm fetal viability, to estimate the gestational age of the fetus, and to detect fetal anomalies early in pregnancy. First trimester ultrasound images have a different appearance than for the second trimester scan, reflecting the different stage of fetal de...

journal_title：Physics in medicine and biology

authors： Ryou H,Yaqub M,Cavallaro A,Papageorghiou AT,Alison Noble J

更新日期：2019-09-17 00:00:00

abstract：:The significance of accurate knowledge of background optical properties and time-resolved information in reconstructing images of hemodynamic changes in the neonatal brain from diffuse optical imaging data was studied using Monte Carlo (MC) simulation. A segmented anatomical magnetic resonance (MR) image and literatur...

journal_title：Physics in medicine and biology

authors： Heiskala J,Hiltunen P,Nissilä I

更新日期：2009-02-07 00:00:00

abstract：:An expression for the noise power spectrum of images reconstructed by the discrete filtered backprojection algorithm has been derived. The formulation explicitly includes sampling within the projections, angular sampling, and the two-dimensional sampling implicit in the discrete representation of the image. The effect...

journal_title：Physics in medicine and biology

authors： Kijewski MF,Judy PF

更新日期：1987-05-01 00:00:00

abstract：:In order to measure in vivo resistivity of tissues in the thorax, the possibility of combining anatomical data extracted from high-resolution images with multiple-electrode impedance measurements, a priori knowledge of the range of tissue resistivities, and a priori data on the instrumentation noise is assessed in thi...

journal_title：Physics in medicine and biology

authors： Eyüboğlu BM,Pilkington TC,Wolf PD

更新日期：1994-01-01 00:00:00

abstract：:At certain frequencies, when the human head becomes a resonant structure, the power absorbed by the head and neck, when the body is exposed to a vertically polarized plane wave propagating from front to back, becomes significantly larger than would ordinarily be expected from its shadow cross section. This has possibl...

journal_title：Physics in medicine and biology

authors： Tinniswood AD,Furse CM,Gandhi OP

更新日期：1998-08-01 00:00:00

abstract：: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...

journal_title：Physics in medicine and biology

authors： Niu Y,Betzel GT,Yang X,Gui M,Parke WC,Yi B,Yu CX

更新日期：2017-02-21 00:00:00

abstract：:The concepts of radiance and fluence are fundamental to the description of a radiation field. The International Commission on Radiological Units and Measurements (ICRU) has defined fluence in terms of the number of the radiation particles crossing a small sampling sphere. A second definition has been proposed in which...

journal_title：Physics in medicine and biology

authors： Papiez L,Battista JJ

更新日期：1994-06-01 00:00:00

abstract：:Kilo-voltage (KV) cone-beam computed tomography (CBCT) unit mounted onto a linear accelerator treatment system, often referred to as on-board imager (OBI), plays an increasingly important role in image-guided radiation therapy. While the FDK algorithm is currently used for reconstructing images from clinical OBI data,...

journal_title：Physics in medicine and biology

authors： Han X,Pearson E,Pelizzari C,Al-Hallaq H,Sidky EY,Bian J,Pan X

更新日期：2015-06-21 00:00:00

abstract：:New values of the factors required to convert the reading of a radiation dosemeter calibrated in terms of air kerma (or exposure) into absorbed dose to water for medium-energy x-radiation were given in a code of practice published by the IAEA in 1987. These are not considered to possess sufficient support from other s...

journal_title：Physics in medicine and biology

authors：

更新日期：1991-08-01 00:00:00

abstract：:The values of the replacement correction factors (P(repl), or in the IAEA's notation p(dis)p(cav)) used for cylindrical chambers in high-energy photon beams represent one of the most significant differences between the AAPM and the IAEA dosimetry protocols. In a previous study (Wang L L W and Rogers D W O 2008 Med. Ph...

journal_title：Physics in medicine and biology

authors： Wang LL,Rogers DW

更新日期：2009-03-21 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：:Noise equivalent count rate (NECR) and image noise are two different but related metrics that have been used to predict and assess image quality, respectively. The aim of this study is to investigate, using patient studies, the relationships between injected dose (ID), body mass index (BMI) and scanner type on NECR an...

journal_title：Physics in medicine and biology

authors： Chang T,Chang G,Kohlmyer S,Clark JW,Rohren E,Mawlawi OR

更新日期：2011-08-21 00:00:00

abstract：:Optically stimulated luminescent dosimeters (OSLDs) are becoming increasingly popular for measuring an absorbed dose in clinical radiotherapy. OSLDs have known energy dependence, and this is accounted for by either calibrating the OSLD with a specific nominal energy, or using a standard energy correction factor to acc...

journal_title：Physics in medicine and biology

authors： Scarboro SB,Followill DS,Kerns JR,White RA,Kry SF

更新日期：2012-05-07 00:00:00

abstract：:The presence of motion artifacts is a typical problem in thoracic imaging. However, synchronizing the respiratory cycle with computed tomography (CT) image acquisition can reduce these artifacts. We currently employ a method of in vivo respiratory-gated micro-CT imaging for small laboratory animals (mice). This proced...

journal_title：Physics in medicine and biology

authors： Walters EB,Panda K,Bankson JA,Brown E,Cody DD

更新日期：2004-09-07 00:00:00

abstract：:An in vivo method for the determination of Cd levels in human kidney and liver has been developed. The method allows detection of absolute quantities of Cd in the left kidney and Cd concentration in the liver. The limit of detection of cadmium is 2.5 mg for the left kidney and 1.8 microgram/g (wet weight) for the live...

journal_title：Physics in medicine and biology

authors： Vartsky D,Ellis KJ,Chen NS,Cohn SH

更新日期：1977-11-01 00:00:00