DAVID--a translucent multi-wire transmission ionization chamber for in vivo verification of IMRT and conformal irradiation techniques.

abstract：:Physical properties of a position-sensitive camera for the analysis of biodistributions of gamma- and beta-emitting radiopharmaceuticals in small animals have been studied, in order to achieve optimal operating conditions. The camera consisted of a highly segmented yttrium-aluminate perovskite (YAP) scintillator, coup...

journal_title：Physics in medicine and biology

authors： Uzunov N,Bello M,Boccaccio P,Moschini G,Baldazzi G,Bollini D,de Notaristefani F,Mazzi U,Riondato M

更新日期：2005-02-07 00:00:00

abstract：:The silicon photomultiplier (Si-PM) is a promising photo-detector for PET for use in magnetic resonance imaging (MRI) systems because it has high gain and is insensitive to static magnetic fields. Recently we developed a Si-PM-based depth-of-interaction PET system for small animals and performed simultaneous measureme...

journal_title：Physics in medicine and biology

authors： Yamamoto S,Watabe T,Watabe H,Aoki M,Sugiyama E,Imaizumi M,Kanai Y,Shimosegawa E,Hatazawa J

更新日期：2012-01-21 00:00:00

abstract：:Recent measurements of differential elastic and inelastic neutron scattering from oxygen, nitrogen and calcium at 18 less than En less than 26 MeV are presented and analysed in terms of the optical model. These data, together with earlier measurements of scattering and total cross sections, are used to construct model...

journal_title：Physics in medicine and biology

authors： Islam MS,Finlay RW,Petler JS,Rapaport J,Alarcon R,Wierzbicki J

更新日期：1988-03-01 00:00:00

abstract：:EEG interictal epileptiform discharges in temporal lobe epilepsy are associated with magnetic fields. The maxima of magnetic spikes recorded over the spherical portions of the head appear fairly symmetric, whereas those over the lower temporal region often have irregular shapes. Furthermore, their magnitude is often u...

journal_title：Physics in medicine and biology

authors： Rose DF,Sato S,Smith PD,White J

更新日期：1987-01-01 00:00:00

abstract：:For image-guided radiotherapy (IGRT) systems based on cone beam CT (CBCT) integrated into a linear accelerator, the reproducible alignment of imager to x-ray source is critical to the registration of both the x-ray-volumetric image with the megavoltage (MV) beam isocentre and image sharpness. An enhanced method of det...

journal_title：Physics in medicine and biology

authors： Sykes JR,Lindsay R,Dean CJ,Brettle DS,Magee DR,Thwaites DI

更新日期：2008-10-07 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：:Dynamic contrast enhanced MRI (DCE-MRI) and pharmacokinetic models have been used to measure tumour permeability (K(trans)) and leakage volume (ve) in numerous studies. The construction of pharmacokinetic models describing such tissue properties relies on defining the blood plasma concentration of contrast agent with ...

journal_title：Physics in medicine and biology

authors： Ahearn TS,Staff RT,Redpath TW,Semple SI

更新日期：2004-05-21 00:00:00

abstract：:The aim of this paper is to determine the dosimetric impact of trace elements in human tissues for low-energy photon sources used in brachytherapy. Monte Carlo dose calculations were used to investigate the dosimetric effect of trace elements present in normal or cancerous human tissues. The effect of individual trace...

journal_title：Physics in medicine and biology

authors： White SA,Landry G,van Gils F,Verhaegen F,Reniers B

更新日期：2012-06-07 00:00:00

abstract：:Values of the relative permittivity and conductivity of the rabbit retina and lens have been measured between 10 MHz and 10 GHz over the temperature range 20 to -20 degrees C. As the temperature was lowered from 20 degrees C the dielectric parameters changed smoothly until -9 degrees C where freezing occurred. At this...

journal_title：Physics in medicine and biology

authors： Gabriel C,Grant EH

更新日期：1985-09-01 00:00:00

abstract：:Currently, energy spectra of laser accelerated proton beams are far from being monoenergetic. For their application in radiation therapy, energy selection systems using magnetic fields have been proposed to single out particles with the desired energy. These systems allow the choice of protons between a lowest and a h...

journal_title：Physics in medicine and biology

authors： Schell S,Wilkens JJ

更新日期：2009-10-07 00:00:00

abstract：:Range verification in proton therapy is a critical quality assurance task. We studied the feasibility of online range verification based on proton-induced acoustic signals, using a bidirectional long-short-term-memory recurrent neural network and various signal processing techniques. Dose distribution of 1D pencil pro...

journal_title：Physics in medicine and biology

authors： Yao S,Hu Z,Zhang X,Lou E,Liang Z,Wang Y,Peng H

更新日期：2020-11-05 00:00:00

abstract：:Fluorescence diffuse optical tomography (fDOT) provides 3D images of fluorescence distributions in biological tissue, which represent molecular and cellular processes. The image reconstruction problem is highly ill-posed and requires regularisation techniques to stabilise and find meaningful solutions. Quadratic regul...

journal_title：Physics in medicine and biology

authors： Correia T,Koch M,Ale A,Ntziachristos V,Arridge S

更新日期：2016-02-21 00:00:00

abstract：:A leaf-setting algorithm is developed for generating arbitrary beam intensity profiles in discrete levels using dynamic multileaf collimators (DMLCs). The algorithm starts with the algebraic expression for the area under the beam profile. It is shown that the coefficients in this expression can be transformed into the...

journal_title：Physics in medicine and biology

authors： Ma L,Boyer AL,Xing L,Ma CM

更新日期：1998-06-01 00:00:00

abstract：:The purpose of this study was to examine the use of three physical image quality metrics in the calibration of an automatic exposure control (AEC) device for chest radiography with a computed radiography (CR) imaging system. The metrics assessed were signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and mean ...

journal_title：Physics in medicine and biology

authors： Moore CS,Wood TJ,Avery G,Balcam S,Needler L,Beavis AW,Saunderson JR

更新日期：2014-05-07 00:00:00

abstract：:Numerical computations are used to evaluate electric field dosimetry for high-resolution anatomically based inhomogeneous models of a human male child, and male and female rats and mice, under exposure to 60 Hz uniform magnetic field sources of three perpendicular orientations. The goal is to compare the child data to...

journal_title：Physics in medicine and biology

authors： Dawson TW,Caputa K,Stuchly MA

更新日期：2002-07-21 00:00:00

abstract：:The delivery of volumetric modulated arc therapy (VMAT) requires the simultaneous movement of the linear accelerator gantry, multi-leaf collimators and jaws while the dose rate is varied. In this study, a VMAT delivery emulator was developed to accurately predict the characteristics of a given treatment plan, incorpor...

journal_title：Physics in medicine and biology

authors： Boylan CJ,Rowbottom CG,Mackay RI

更新日期：2011-07-07 00:00:00

abstract：:Optical topography is a method for visualization of conical activity. Ways of improving the spatial resolution of the topographical image with three arrangements of optical fibres are discussed. A distribution of sensitivity is obtained from the phantom experiment, and used to reconstruct topographical images of an ac...

journal_title：Physics in medicine and biology

authors： Yamamoto T,Maki A,Kadoya T,Tanikawa Y,Yamad Y,Okada E,Koizumi H

更新日期：2002-09-21 00:00:00

abstract：:For conventional irradiation devices, the radiation isocenter accuracy is determined by star shot measurements on films. In magnetic resonance (MR)-guided radiotherapy devices, the results of this test may be altered by the magnetic field and the need to align the radiation and imaging isocenter may require a modifica...

journal_title：Physics in medicine and biology

authors： Dorsch S,Mann P,Lang C,Haering P,Runz A,Karger CP

更新日期：2018-05-29 00:00:00

abstract：:The 'monoenergetic' electron loss model was derived in a previous work to account for pathlength straggling in the Fermi-Eyges pencil beam problem. In this paper, we extend this model to account for energy-loss straggling and secondary knock-on electron transport in order to adequately predict a depth dose curve. To m...

journal_title：Physics in medicine and biology

authors： Chvetsov AV,Sandison GA,Yeboah C

更新日期：2000-10-01 00:00:00

abstract：:The measurement of output factors (OF) for the small photon beams generated by Leksell Gamma Knife® (LGK) radiotherapy units is a challenge for the physicist due to the under or over estimation of these factors by a vast majority of the detectors commercially available. Output correction factors, introduced in the int...

journal_title：Physics in medicine and biology

authors： Benmakhlouf H,Johansson J,Paddick I,Andreo P

更新日期：2015-05-21 00:00:00

abstract：:For proton therapy, an accurate conversion of CT HU to relative stopping power (RSP) is essential. Validation of the conversion based on real tissue samples is more direct than the current practice solely based on tissue substitutes and can potentially address variations over the population. Based on a novel dose exti...

journal_title：Physics in medicine and biology

authors： Zhang R,Baer E,Jee KW,Sharp GC,Flanz J,Lu HM

更新日期：2017-06-23 00:00:00

abstract：:The analysis of (x-ray) mammograms remains qualitative, relying on the judgement of clinicians. We present a novel method to compute a quantitative, normalized measure of tissue radiodensity traversed by the primary beam incident on each pixel of a mammogram, a measure we term the standard attenuation rate (SAR). SAR ...

journal_title：Physics in medicine and biology

authors： Tromans CE,Cocker MR,Brady SM

更新日期：2012-10-21 00:00:00

abstract：:Recent research has suggested that endothelialization of vascular stents is crucial to reducing the risk of late stent thrombosis. With a resolution of approximately 10 microm, optical coherence tomography (OCT) may be an appropriate imaging modality for visualizing the vascular response to a stent and measuring the p...

journal_title：Physics in medicine and biology

authors： Bonnema GT,Cardinal KO,Williams SK,Barton JK

更新日期：2008-06-21 00:00:00

abstract：:Ankylosing spondylitis is a disease characterized by abnormal bone formation (syndesmophyte) at the margins of inter-vertebral disc spaces. Syndesmophyte growth is currently typically monitored by the visual inspection of radiographs. The limitations inherent to the modality (2D projection of a 3D object) and rater (q...

journal_title：Physics in medicine and biology

authors： Tan S,Yao J,Yao L,Ward MM

更新日期：2012-07-21 00:00:00

abstract：:We experimentally investigated the SPECT recovery of I-131 activity in multiple spheres located simultaneously at different locations within a cylindrical phantom that had an elliptical cross section. The sphere volumes ranged from 209 cc down to 4.2 cc. A Prism 3000 camera and two types of parallel-hexagonal-hole col...

journal_title：Physics in medicine and biology

authors： Koral KF,Yendiki A,Dewaraja YK

更新日期：2007-02-07 00:00:00

abstract：:The University of Washington (UW) Clinical Neutron Therapy System (CNTS) has been used to treat over 3300 patients. Treatment planning for these patients is currently performed using an MV x-ray model in Pinnacle® adapted to fit measurements of fast neutron output factors, wedge factors, depth-dose and lateral profile...

journal_title：Physics in medicine and biology

authors： Moffitt GB,Wootton LS,Hårdemark B,Sandison GA,Laramore GE,Parvathaneni U,Stewart RD

更新日期：2020-08-31 00:00:00

abstract：:In dual energy x-ray absorptiometry (DXA) the photon attenuation is assumed to be similar in soft tissue overlying, adjacent to and inside the measured bone. In the calcaneal dual energy x-ray laser (DXL) technique, this assumption is not needed as attenuation by soft tissues at the local bone site is determined by co...

journal_title：Physics in medicine and biology

authors： Hakulinen MA,Saarakkala S,Töyräs J,Kröger H,Jurvelin JS

更新日期：2003-06-21 00:00:00

abstract：:Fully three-dimensional positron emission tomography is considered and a reconstruction algorithm derived. The reconstruction problem is formulated mathematically as a three-dimensional convolution integral of a point spread function with an unknown positron activity distribution and is solved by Fourier transform met...

journal_title：Physics in medicine and biology

authors： Colsher JG

更新日期：1980-01-01 00:00:00

abstract：:A dynamic-contrast-enhanced magnetic resonance imaging (DCE-MRI) dataset consists of many imaging frames, often acquired both before and after contrast injection. Due to the length of time spent acquiring images, patient motion is likely and image re-alignment or registration is required before further analysis such a...

journal_title：Physics in medicine and biology

authors： Melbourne A,Hipwell J,Modat M,Mertzanidou T,Huisman H,Ourselin S,Hawkes DJ

更新日期：2011-12-21 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