In vivo and in vitro dielectric properties of feline tissues at low radiofrequencies.

abstract：:Ion beam radiotherapy exploits the finite range of ion beams and the increased dose deposition of ions toward the end of their range in material. This results in high dose conformation to the target region, which can be further increased using scanning ion beams. The standard method for patient-plan verification in io...

journal_title：Physics in medicine and biology

authors： Martišíková M,Brons S,Hesse BM,Jäkel O

更新日期：2013-03-21 00:00:00

abstract：:Over the past few years there has been much interest in the development of three-dimensional dosimeters to determine the complex absorbed dose distribution in modern radiotherapy techniques such as IMRT and IGRT. In routine methods used for three-dimensional dosimetry, polymer gels are commonly used. Recently, a novel...

journal_title：Physics in medicine and biology

authors： Mostaar A,Hashemi B,Zahmatkesh MH,Aghamiri SM,Mahdavi SR

更新日期：2010-02-07 00:00:00

abstract：:The High-Resolution Research Tomograph (HRRT) is a dedicated human brain positron emission tomography (PET) scanner. Recently, a 3D filtered backprojection (3D-FBP) reconstruction method has been implemented to reduce bias in short duration frames, currently observed in 3D ordinary Poisson OSEM (3D-OP-OSEM) reconstruc...

journal_title：Physics in medicine and biology

authors： van Velden FH,Kloet RW,van Berckel BN,Wolfensberger SP,Lammertsma AA,Boellaard R

更新日期：2008-06-21 00:00:00

abstract：:The MRI accelerator, a combination of a 6 MV linear accelerator with a 1.5 T MRI, facilitates continuous patient anatomy updates regarding translations, rotations and deformations of targets and organs at risk. Accounting for these demands high speed, online intensity-modulated radiotherapy (IMRT) re-optimization. In ...

journal_title：Physics in medicine and biology

authors： Bol GH,Hissoiny S,Lagendijk JJ,Raaymakers BW

更新日期：2012-03-07 00:00:00

abstract：:Electron depth-dose curves and spectra have been measured from an experimental accelerator on which both energy and spectral shape could be varied independently. The measurements were made at nominal energies of 6 and 12 MeV, with the energy spread (FWHM) varied from 1.7% to over 10% of average energy. Changes in dept...

journal_title：Physics in medicine and biology

authors： Johnsen SW,LaRiviere PD,Tanabe E

更新日期：1983-12-01 00:00:00

abstract：:RapidArc, recently released by Varian Medical Systems, is a novel extension of IMRT in which an optimized 3D dose distribution may be delivered in a single gantry rotation of 360 degrees or less. The purpose of this study was to investigate the accuracy of the analytical anisotropic algorithm (AAA), the sole algorithm...

journal_title：Physics in medicine and biology

authors： Gagne IM,Ansbacher W,Zavgorodni S,Popescu C,Beckham WA

更新日期：2008-12-21 00:00:00

abstract：:The standard mammogram form (SMF) representation of an x-ray mammogram is a standardized, quantitative representation of the breast from which the volume of non-fat tissue and breast density can be easily estimated, both of which are of significant interest in determining breast cancer risk. Previous theoretical analy...

journal_title：Physics in medicine and biology

authors： Highnam R,Pan X,Warren R,Jeffreys M,Davey Smith G,Brady M

更新日期：2006-06-07 00:00:00

abstract：:Single energy x-ray analysis is explored in the context of computed tomography (CT), whereby Hounsfield numbers (HN) are used to estimate electron density N(e) and parameters that describe composition. We examine measurements with tissue substitute materials and theoretical HN for a broad range of tissues. Results are...

journal_title：Physics in medicine and biology

authors： Midgley SM

更新日期：2012-12-07 00:00:00

abstract：:The trend towards conformal, intensity modulated radiotherapy treatments has established the need for a true integrating dosimeter. In traditional radiotherapy, radiographic film dosimetry is commonly used. The accuracy and reproducibility of film optical density as an indicator of dose is influenced by several variab...

journal_title：Physics in medicine and biology

authors： Suchowerska N,Hoban P,Butson M,Davison A,Metcalfe P

更新日期：2001-05-01 00:00:00

abstract：:Multileaf collimators (MLCs) have been in clinical use for many years and meanwhile are commonly used to deliver intensity-modulated radiotherapy (IMRT) beams. For this purpose it is important to know their dosimetric properties precisely, one of them being inter- and intraleaf leakage. The Siemens 160 MLC features a ...

journal_title：Physics in medicine and biology

authors： Klüter S,Sroka-Perez G,Schubert K,Debus J

更新日期：2011-01-21 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：:Fast heat extraction is critically important to obtain the maximal benefit of cryogen spray cooling (CSC) during laser therapy of shallow skin lesions, such as port wine stain birthmarks. However, a film of liquid cryogen can build up on the skin surface, impairing heat transfer due to the relatively low thermal condu...

journal_title：Physics in medicine and biology

authors： Majaron B,Svaasand LO,Aguilar G,Nelson JS

更新日期：2002-09-21 00:00:00

abstract：:Monte Carlo simulations were used to investigate large-angle x-ray scatter at design energy of 25 keV during small field of view (9.6 cm × 5 cm) differential phase contrast imaging of the breast using Talbot-Lau interferometry. Homogenous, adipose and fibroglandular breasts of uniform thickness ranging from 2 to 8 cm ...

journal_title：Physics in medicine and biology

authors： Vedantham S,Shi L,Karellas A

更新日期：2014-11-07 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：:This paper presents two 4D mathematical observer models for the detection of motion defects in 4D gated medical images. Their performance was compared with results from human observers in detecting a regional motion abnormality in simulated 4D gated myocardial perfusion (MP) SPECT images. The first 4D mathematical obs...

journal_title：Physics in medicine and biology

authors： Lee TS,Frey EC,Tsui BM

更新日期：2015-04-07 00:00:00

abstract：:Recently, the initial 2D physical characterization of a small-diameter positron emission tomograph, designed specifically for scanning of small laboratory animals, was reported. The physical characteristics of the tomograph operating in 3D mode have now been measured and compared to those obtained in 2D mode. In 3D, t...

journal_title：Physics in medicine and biology

authors： Bloomfield PM,Myers R,Hume SP,Spinks TJ,Lammertsma AA,Jones T

更新日期：1997-02-01 00:00:00

abstract：:In BANG gel dosimetry, the spin-spin relaxation rate, R2 = I/T2, is related to the radiation dose that has been delivered to the gel phantom. R2 is calculated by fitting the pixel intensities of a set of differently T2-weighted base images. In gel dosimetry for radiotherapy, an accuracy of 5% in dose and 3 mm spatiall...

journal_title：Physics in medicine and biology

authors： De Deene Y,De Wagter C,De Neve W,Achten E

更新日期：2000-07-01 00:00:00

abstract：:We examine how the choice of CT x-ray beam filtration and phantom size influences patient dose (D) to computed tomography dose index (CTDI) conversion factors (i.e. D/CTDI). The ratio of head to body phantom CTDI(w) for a defined scan technique is alpha, and the ratio of organ dose when the body filter is changed to t...

journal_title：Physics in medicine and biology

authors： Huda W,Sterzik A,Tipnis S

更新日期：2010-01-21 00:00:00

abstract：:Inverse planning techniques are known to produce intensity-modulated beams (IMBs) that are highly modulated. They are characterized by the fact that they contain high-frequency modulations that are absent in the profiles that are easier to deliver. For the purpose of this study these clinically unwanted fluctuations a...

journal_title：Physics in medicine and biology

authors： Coolens C,Evans PM,Seco J,Webb S

更新日期：2004-09-07 00:00:00

abstract：:A technique is presented to allow a breathing pattern to be obtained from any multi-slice CT, cone-beam or other series of sequential chest x-ray image sets. The technique requires no extra signals to be recorded and does not need specific external or internal oscillating structures to be visible in the field of view....

journal_title：Physics in medicine and biology

authors： Kavanagh A,Evans PM,Hansen VN,Webb S

更新日期：2009-08-21 00:00:00

abstract：:An algorithm for dynamic multileaf-collimator (dMLC) tracking of a target performing a known a priori, rigid-body motion during volumetric modulated arc therapy (VMAT), has been experimentally validated and applied to investigate the potential of the Agility (Elekta AB, Stockholm, Sweden) multileaf-collimator (MLC) fo...

journal_title：Physics in medicine and biology

authors： Davies GA,Clowes P,Bedford JL,Evans PM,Webb S,Poludniowski G

更新日期：2013-07-07 00:00:00

abstract：:Reliable treatment planning of highly conformal scanned ion beam therapy demands accurate tools for the determination and characterization of the individual pencil-like beams building up the integral dose delivery and related mixed radiation field. At present, clinically practicable inverse treatment planning systems ...

journal_title：Physics in medicine and biology

authors： Parodi K,Mairani A,Brons S,Hasch BG,Sommerer F,Naumann J,Jäkel O,Haberer T,Debus J

更新日期：2012-06-21 00:00:00

abstract：:In recent years, the Monte Carlo method has been used in a large number of research studies in radiation therapy. For applications such as treatment planning, it is essential to validate the dosimetric accuracy of the Monte Carlo simulations in heterogeneous media. The AAPM Report no 105 addresses issues concerning cl...

journal_title：Physics in medicine and biology

authors： Titt U,Sahoo N,Ding X,Zheng Y,Newhauser WD,Zhu XR,Polf JC,Gillin MT,Mohan R

更新日期：2008-08-21 00:00:00

abstract：:The effects of radiation damage, tumour repopulation and cell sublethal damage repair and the possibility of extracting information about the model parameters describing them are investigated in this work. Previously published data on two different cultured cell lines were analysed with the help of a tumour control pr...

journal_title：Physics in medicine and biology

authors： Stavrev P,Weldon M,Warkentin B,Stavreva N,Fallone BG

更新日期：2005-07-07 00:00:00

abstract：:A cost-effective method employing polysulphone, nalidixic acid, 8-methoxypsoralen and phenothiazine as UV dosimeters is presented for evaluating the UV spectrum. The exposure measured by each dosimeter is a function of the source spectrum and the spectral response of the material. Each material has a different spectra...

journal_title：Physics in medicine and biology

authors： Parisi AV,Wong JC,Moore GI

更新日期：1997-01-01 00:00:00

abstract：:The accuracy of delivered radiation dose and the reproducibility of employed radiotherapy methods are key factors for preclinical radiobiology applications and research studies. In this work, ionization chamber (IC) measurements and Monte Carlo (MC) simulations were used to accurately determine the dose rate for total...

journal_title：Physics in medicine and biology

authors： Zhong Y,Lai Y,Saha D,Story MD,Jia X,Stojadinovic S

更新日期：2020-09-08 00:00:00

abstract：:Dental tomographic cone-beam x-ray imaging devices record truncated projections and reconstruct a region of interest (ROI) inside the head. Image reconstruction from the resulting local tomography data is an ill-posed inverse problem. A new Bayesian multiresolution method is proposed for local tomography reconstructio...

journal_title：Physics in medicine and biology

authors： Niinimäki K,Siltanen S,Kolehmainen V

更新日期：2007-11-21 00:00:00

abstract：:The automatic calibration in Fourier-domain optical coherence tomography (FD-OCT) systems allows for high resolution imaging with precise depth ranging functionality in many complex imaging scenarios, such as microsurgery. However, the accuracy and speed of the existing automatic schemes are limited due to the functio...

journal_title：Physics in medicine and biology

authors： Ratheesh KM,Seah LK,Murukeshan VM

更新日期：2016-11-07 00:00:00

abstract：:The aim of this study was to investigate the utility of consistency metrics, such as inverse consistency, in contour-based deformable registration error analysis. Four images were acquired of the same phantom that has experienced varying levels of deformation. The deformations were simulated with deformable image regi...

journal_title：Physics in medicine and biology

authors： Bender ET,Tomé WA

更新日期：2009-09-21 00:00:00

abstract：:To increase the scanning speed of cone-beam CT, a scanning configuration with three pairs of x-ray sources and panel detectors was proposed. In this paper, we apply the M-line-based backprojected filtration algorithm to this scanning configuration and propose a fast implementation for this algorithm. Compared with exi...

journal_title：Physics in medicine and biology

authors： Zhao Y,Zhu Y,Zhang P

更新日期：2010-12-07 00:00:00