Glandular dose in breast computed tomography with synchrotron radiation.

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 first goal of this paper is to clarify the reference conditions for the reference dosimetry of clinical proton beams. A clear distinction is made between proton beam delivery systems which should be calibrated with a spread-out Bragg peak field and those that should be calibrated with a (pseudo-)monoenergetic prot...

journal_title：Physics in medicine and biology

authors： Gomà C,Lorentini S,Meer D,Safai S

更新日期：2014-09-07 00:00:00

abstract：:An acardiac twin is a severely malformed monochorionic twin fetus that lacks most organs, particularly a heart. It grows during pregnancy, because it is perfused by its developmentally normal co-twin (called the pump twin) via a set of placental arterioarterial and venovenous anastomoses. The pump twin dies intrauteri...

journal_title：Physics in medicine and biology

authors： Umur A,van Gemert MJ,van den Wijngaard JP,Ross MG,Nikkels PG

更新日期：2004-07-21 00:00:00

abstract：:Conversion factors, which relate the kerma-area product to effective dose, have been estimated for paediatric cardiac x-ray angiography. Monte Carlo techniques have been used to calculate the conversion factors for a wide range of projection angles for children of five ages and for adults. Correction factors are provi...

journal_title：Physics in medicine and biology

authors： Schmidt PW,Dance DR,Skinner CL,Smith IA,McNeill JG

更新日期：2000-10-01 00:00:00

abstract：:Practical dosimeters in brachytherapy, such as thermoluminescent dosimeters (TLD) and diodes, are usually calibrated against low-energy megavoltage beams. To measure absolute dose rate near a brachytherapy source, it is necessary to establish the energy response of the detector relative to that of the calibration ener...

journal_title：Physics in medicine and biology

authors： Das RK,Li Z,Perera H,Williamson JF

更新日期：1996-06-01 00:00:00

abstract：:In the current work, EPR (electron paramagnetic resonance) dosimetry using alanine films (134 microm thick) was utilized for dose measurements in inhomogeneous phantoms irradiated with radiotherapy photon beams. The main phantom material was PMMA, while either Styrofoam or aluminium was introduced as an inhomogeneity....

journal_title：Physics in medicine and biology

authors： Osterås BH,Hole EO,Olsen DR,Malinen E

更新日期：2006-12-21 00:00:00

abstract：:A method is described which offers an alternative to conventional Fourier phase/amplitude imaging for analysing representative LV cycles obtained from first-pass cardiac studies. The method involves applying factor analysis to the data and producing functional images of the first two factor loadings after polar transf...

journal_title：Physics in medicine and biology

authors： Houston AS,Elliott AT,Stone DL

更新日期：1982-10-01 00:00:00

abstract：:Monte Carlo calculations of the energy response of LiF dosemeters have been carried out to help resolve the discrepancy between the measurements of Holt, Edelstein and Clark (1975) and those of Paliwal and Almond (1975) and others. It is concluded that the assumptions used by Holt et al. are largely responsible. They ...

journal_title：Physics in medicine and biology

authors： O'Brien K

更新日期：1977-09-01 00:00:00

abstract：:Monte Carlo simulations are used to investigate skin dose resulting from chest wall radiotherapy with bolus. A simple model of a female thorax is developed, which includes a 2 mm-thick skin layer. Two representative 6 MV source models are considered: a tangents source model consisting of a parallel opposed pair of med...

journal_title：Physics in medicine and biology

authors： Oliver PAK,Monajemi TT

更新日期：2020-08-11 00:00:00

abstract：:In charged particle therapy with pencil beam scanning (PBS), localization of the dose in the Bragg peak makes dose distributions sensitive to lateral tissue heterogeneities. The sensitivity of a PBS plan to lateral tissue heterogeneities can be reduced by selecting appropriate beam angles. The purpose of this study is...

journal_title：Physics in medicine and biology

authors： Toramatsu C,Inaniwa T

更新日期：2016-12-21 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：:Deformable image registration is widely used in various radiation therapy applications including daily treatment planning adaptation to map planned tissue or dose to changing anatomy. In this work, a simple and efficient inverse consistency deformable registration method is proposed with aims of higher registration ac...

journal_title：Physics in medicine and biology

authors： Yang D,Li H,Low DA,Deasy JO,El Naqa I

更新日期：2008-11-07 00:00:00

abstract：:We investigate an optimization-based reconstruction, with an emphasis on image-artifact reduction, from data collected in C-arm cone-beam computed tomography (CBCT) employed in image-guided interventional procedures. In the study, an image to be reconstructed is formulated as a solution to a convex optimization progra...

journal_title：Physics in medicine and biology

authors： Xia D,Langan DA,Solomon SB,Zhang Z,Chen B,Lai H,Sidky EY,Pan X

更新日期：2016-10-21 00:00:00

abstract：:A novel digital x-ray detector has been assembled. The imaging system is based on a phosphor-coated charge-coupled device (CCD) obtained by direct deposition of a gadolinium oxysulphide scintillator onto the detector surface. The modulation transfer function has been measured along the two directions of the digital co...

journal_title：Physics in medicine and biology

authors： Gambaccini M,Taibi A,Del Guerra A,Marziani M,Tuffanelli A

更新日期：1996-12-01 00:00:00

abstract：:Both inhomogeneity in the main magnetic field and non-linearity in the gradient fields introduce errors in NMR images reconstructed from projections. It is found that the image artefacts caused by these two sources are separable. The inhomogeneous main field blurs the image while the nonlinear gradients distort the im...

journal_title：Physics in medicine and biology

authors： Lai CM

更新日期：1983-08-01 00:00:00

abstract：:Infrared measurements have been used to profile or image biological tissue, including human skin. Usually, analysis of such measurements has assumed that infrared absorption is due to water and collagen. Such an assumption may be reasonable for soft tissue, but introduction of exogenous agents into skin or the measure...

journal_title：Physics in medicine and biology

authors： Viator JA,Choi B,Peavy GM,Kimel S,Nelson JS

更新日期：2003-01-21 00:00:00

abstract：:There are three ways to determine the spectrum of a clinical photon beam: direct measurement, modelling the source and reconstruction from ion-chamber measurements. We focus on reconstruction because the necessary equipment is readily available and it provides independent confirmation of source models for a given mach...

journal_title：Physics in medicine and biology

authors： Armbruster B,Hamilton RJ,Kuehl AK

更新日期：2004-11-21 00:00:00

abstract：:Measurement of total body nitrogen is assuming increasing importance in the nutritional evaluation of seriously ill patients. Nitrogen has been previously measured either by counting (i) the annihilation radiation from 13N immediately after neutron irradiation with 14 MeV neutrons or (ii) the 'prompt' gamma rays from ...

journal_title：Physics in medicine and biology

authors： Spinks TJ,Goode AW,Ranicar AS,Steere E

更新日期：1984-04-01 00:00:00

abstract：:Awake and/or freely moving small animal single photon emission imaging allows the continuous study of molecules exhibiting slow kinetics without the need to restrain or anaesthetise the animals. Estimating motion free projections in freely moving small animal planar imaging can be considered as a limited angle tomogra...

journal_title：Physics in medicine and biology

authors： Angelis GI,Ryder WJ,Gillam JE,Boisson F,Kyme AZ,Fulton RR,Meikle SR,Kench PL

更新日期：2017-05-21 00:00:00

abstract：:In medical imaging different techniques have been developed to gain information from inside a tissue. Optoacoustics is a method to generate tomography pictures of tissue using Q-switched laser pulses. Due to thermal and pressure confinement, a short light pulse generates a pressure distribution inside tissue, which mi...

journal_title：Physics in medicine and biology

authors： Köstli KP,Frenz M,Bebie H,Weber HP

更新日期：2001-07-01 00:00:00

abstract：:Coherent x-rays from synchrotron sources are increasingly used in non-conventional radiological techniques ('phase-contrast' radiology). Our experiments demonstrate that by using white (unmonochromatic) radiation and a time-resolving system, it is possible to image microscopic details of moving blood vessels in differ...

journal_title：Physics in medicine and biology

authors： Hwu Y,Tsai WL,Je JH,Seol SK,Kim B,Groso A,Margaritondo G,Lee KH,Seong JK

更新日期：2004-02-21 00:00:00

abstract：:In this work, a methodology for using a smartphone camera, in conjunction with a light-tight box operating in reflective transmission mode, is investigated as a proof of concept for use as a film dosimetry system. An imaging system was designed to allow the camera of a smartphone to be used as a pseudo densitometer. T...

journal_title：Physics in medicine and biology

authors： Aland T,Jhala E,Kairn T,Trapp J

更新日期：2017-10-03 00:00:00

abstract：:This paper presents finite-difference time-domain (FDTD) calculations of the whole-body averaged SAR in an anatomically realistic voxel model of the human body. This model, NORMAN, consists of approximately 9 million voxels, of 2 mm dimension in the adult phantom, segmented into 37 tissue types. SAR values are present...

journal_title：Physics in medicine and biology

authors： Dimbylow PJ

更新日期：1997-03-01 00:00:00

abstract：:The in-phantom calibration method for radiotherapy kilovoltage x-ray beams requires ionization chamber correction factors. The overall ionization chamber correction factor accounts for changes in the chamber response due to the displacement of water by the chamber cavity and wall, the presence of the stem and the chan...

journal_title：Physics in medicine and biology

authors： Bancheri J,Ketelhut S,Büermann L,Seuntjens J

更新日期：2020-05-11 00:00:00

abstract：:In clinical computed tomography (CT) images, cortical bone features with sub-millimeter (sub-mm) thickness are substantially blurred, such that their thickness is overestimated and their intensity appears underestimated. Therefore, any inquiry of the geometry or the density of such bones based on these images is sever...

journal_title：Physics in medicine and biology

authors： Pakdel A,Robert N,Fialkov J,Maloul A,Whyne C

更新日期：2012-12-07 00:00:00

abstract：:In recent years, particle therapy has become a widely accepted form of cancer treatment and technological advances in beam delivery technology (i.e. pencil beam scanning (PBS)) have enabled the application of highly conformal dose distributions to static targets. Current research focuses on the possibilities for the t...

journal_title：Physics in medicine and biology

authors： Bernatowicz K,Lomax AJ,Knopf A

更新日期：2013-11-21 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：:In this paper, we present a segmentation and classification method for thyroid follicular neoplasms based on a combination of the prior-based level set method and deep convolutional neural network. The proposed method aims to discriminate thyroid follicular adenoma (TFA) and follicular thyroid carcinoma (FTC) in ultra...

journal_title：Physics in medicine and biology

authors： Yang B,Yan M,Yan Z,Zhu C,Xu D,Dong F

更新日期：2020-11-02 00:00:00

abstract：:In a previous paper the calibration of an isotropic light detector in clear media was described and validated. However, in most applications the detector is used to measure light distribution in turbid (scattering) media, that is, in tissues or tissue equivalent optical phantoms. Despite its small diameter (typically ...

journal_title：Physics in medicine and biology

authors： Marijnissen JP,Star WM

更新日期：2002-06-21 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