Calculation of turnover rates in stable-isotope studies.

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：:This study aims at investigating in real-time the structural and dynamical changes occurring in an ex vivo tissue during a microwave thermal ablation (MTA) procedure. The experimental set-up was based on ex vivo liver tissue inserted in a dedicated box, in which 3 fibre-optic (FO) temperature probes were introduced to...

journal_title：Physics in medicine and biology

authors： Strigari L,Minosse S,D'Alessio D,Farina L,Cavagnaro M,Cassano B,Pinto R,Vallati G,Lopresto V

更新日期：2019-05-31 00:00:00

abstract：:Segmented attenuation correction is now a widely accepted technique to reduce noise propagation from transmission scanning in positron emission tomography (PET). In this paper, we present a new method for segmenting transmission images in whole-body scanning. This reduces the noise in the correction maps while still c...

journal_title：Physics in medicine and biology

authors： Zaidi H,Diaz-Gomez M,Boudraa A,Slosman DO

更新日期：2002-04-07 00:00:00

abstract：:Exploiting the field response of magnetic tracers, magnetic particle imaging (MPI) allows direct, local quantification of the tracer concentration in bulk structures. Here, we investigated the use of characteristic field response functions to spatially resolve the absolute concentration of multiple nanoparticle specie...

journal_title：Physics in medicine and biology

authors： Han SH,Cho E,Lee DK,Cho G,Kim YR,Cho H

更新日期：2014-11-07 00:00:00

abstract：:Following the publication of ICRU Report 50, the concepts of GTV (gross tumour volume). CTV (clinical target volume) and PTV (planning target volume) are being used in radiotherapy planning with increasing frequency. In 3D planning, the GTV (or CTV) is normally outlined by the clinician in CT or MRI slices. The PTV is...

journal_title：Physics in medicine and biology

authors： Stroom JC,Storchi PR

更新日期：1997-04-01 00:00:00

abstract：:Diffraction-enhanced imaging (DEI) is an analyser-based x-ray imaging method that produces separate images depicting the projected x-ray absorption and refractive properties of an object. Because the imaging model of DEI does not account for ultra-small-angle x-ray scattering (USAXS), the images produced in DEI can co...

journal_title：Physics in medicine and biology

authors： Chou CY,Anastasio MA,Brankov JG,Wernick MN,Brey EM,Connor DM,Zhong Z

更新日期：2007-04-07 00:00:00

abstract：:Three-dimensional reconstruction of coronary arteries can be performed during x-ray-guided interventions by gated reconstruction from a rotational coronary angiography sequence. Due to imperfect gating and cardiac or breathing motion, the heart's motion state might not be the same in all projections used for the recon...

journal_title：Physics in medicine and biology

authors： Hansis E,Schäfer D,Dössel O,Grass M

更新日期：2008-07-21 00:00:00

abstract：:A software program, SpekCalc, is presented for the calculation of x-ray spectra from tungsten anode x-ray tubes. SpekCalc was designed primarily for use in a medical physics context, for both research and education purposes, but may also be of interest to those working with x-ray tubes in industry. Noteworthy is the p...

journal_title：Physics in medicine and biology

authors： Poludniowski G,Landry G,DeBlois F,Evans PM,Verhaegen F

更新日期：2009-10-07 00:00:00

abstract：:A modified sector-integration method is presented that can predict the output factors of irregular shaped electron fields even in the case of extended source to surface distance (SSD). The model takes as input measured output factors for circular inserts of various radii. These circular fields were measured at SSDs of...

journal_title：Physics in medicine and biology

authors： Choi DR,Wolters J,Mason D,Baillie A

更新日期：2000-11-01 00:00:00

abstract：:Estimation of a set of parameters that describe the geometry of the cone-beam computed tomography system plays an important role in the geometrical calibration. In the calibration process, the helical phantom consisting of spherical markers arranged on a helical trajectory has been widely applied. To directly determin...

journal_title：Physics in medicine and biology

authors： Xu M,Zhang C,Liu X,Li D

更新日期：2014-10-07 00:00:00

abstract：:The clinical value of multiple b-value diffusion-weighted (DW) magnetic resonance imaging (MRI) has been shown in many studies. However, DW-MRI often suffers from low signal-to-noise ratio, especially at high b-values. To address this limitation, we present an image denoising method based on the concept of deep image ...

journal_title：Physics in medicine and biology

authors： Lin YC,Huang HM

更新日期：2020-05-11 00:00:00

abstract：:Image reconstruction of ultrasound computed tomography based on the wave equation is able to show much more structural details than simpler ray-based image reconstruction methods. However, to invert the wave-based forward model is computationally demanding. To address this problem, we develop an efficient fully learne...

journal_title：Physics in medicine and biology

authors： Zhao W,Wang H,Gemmeke H,van Dongen KWA,Hopp T,Hesser J

更新日期：2020-11-27 00:00:00

abstract：:In this paper we present a novel method of reducing the dosimetric effects of the finite leaf width of a multileaf collimator (MLC) in conformal and intensity modulated radiotherapy (IMRT). This is achieved by decomposing the required high-resolution fluence distribution into two orthogonal components, which are deliv...

journal_title：Physics in medicine and biology

authors： Evans PM,Partridge M

更新日期：2000-03-01 00:00:00

abstract：:It is difficult to test near-infrared spectrophotometry instruments in vivo. Therefore we constructed a liquid phantom which mimics the neonatal head. It consists of a spherical 3.5 mm thick layer of silicone rubber simulating skin and bone and a 0.5 mm thick clear layer of polypropylene imitating cerebrospinal fluid....

journal_title：Physics in medicine and biology

authors： Wolf M,Keel M,Dietz V,von Siebenthal K,Bucher HU,Baenziger O

更新日期：1999-07-01 00:00:00

abstract：:Data filtering is crucial for accurate relative stopping power (RSP) reconstruction in proton CT (pCT). In this work, we assess different filters and their performance for the US pCT collaboration prototype pCT system in Monte Carlo (MC) simulations. The potential of using the recently proposed [Formula: see text]-E f...

journal_title：Physics in medicine and biology

authors： Volz L,Piersimoni P,Johnson RP,Bashkirov VA,Schulte RW,Seco J

更新日期：2019-08-01 00:00:00

abstract：:A novel meshless reconstruction algorithm for digital tomosynthesis (DT) is presented and assessed against experimental data. The algorithm does not require a three-dimensional grid or mesh allocation and performs a slice-by-slice reconstruction where each slice position can be chosen at runtime. The methodology is ba...

journal_title：Physics in medicine and biology

authors： Soloviev VY,Renforth KL,Dirckx CJ,Wells SG

更新日期：2020-04-20 00:00:00

abstract：:An experimental determination of the energy correction factor for alanine/paraffin pellets in the 192Ir spectrum at varying distances from the source is presented. Alanine dosimeters were irradiated in water under full scatter conditions with a high dose rate (HDR) 192Ir source (Flexisource), using a dedicated holder....

journal_title：Physics in medicine and biology

authors： Schaeken B,Cuypers R,Goossens J,Van den Weyngaert D,Verellen D

更新日期：2011-10-21 00:00:00

abstract：:Multi-atlas segmentation (MAS) has been widely used to automate the delineation of organs at risk (OARs) for radiotherapy. Label fusion is a crucial step in MAS to cope with the segmentation variabilities among multiple atlases. However, most existing label fusion methods do not consider the potential dosimetric impac...

journal_title：Physics in medicine and biology

authors： Chang J,Tian Z,Lu W,Gu X,Chen M,Jiang SB

更新日期：2017-05-07 00:00:00

abstract：:Fluorescence molecular imaging/tomography may play an important future role in preclinical research and clinical diagnostics. Time- and frequency-domain fluorescence imaging can acquire more measurement information than the continuous wave (CW) counterpart, improving the image quality of fluorescence molecular tomogra...

journal_title：Physics in medicine and biology

authors： Lu Y,Zhu B,Shen H,Rasmussen JC,Wang G,Sevick-Muraca EM

更新日期：2010-08-21 00:00:00

abstract：:In treatment planning we depend upon accurate knowledge of geometric and range uncertainties. If the uncertainty model is inaccurate then the plan will produce under-dosing of the target and/or overdosing of OAR. We aim to provide a method for which centre and site-specific population range uncertainty due to inter-fr...

journal_title：Physics in medicine and biology

authors： Holloway SM,Holloway MD,Thomas SJ

更新日期：2017-12-19 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：:Using a statistical (chi-square) test on simulated data and a realistic noise model derived from the system's hardware we study the performance of diffuse optical tomography systems for fluorescence imaging. We compare the predicted smallest size of detectable lesions at various positions in slab and cup geometry and ...

journal_title：Physics in medicine and biology

authors： Ziegler R,Brendel B,Rinneberg H,Nielsen T

更新日期：2009-01-21 00:00:00

abstract：:A finite element thermal model of the head has been developed to calculate temperature rises generated in the brain by radiation from cellular telephones and similar electromagnetic devices. A 1 mm resolution MRI dataset was segmented semiautomatically, assigning each volume element to one of ten tissue types. A finit...

journal_title：Physics in medicine and biology

authors： Wainwright P

更新日期：2000-08-01 00:00:00

abstract：:A new function to treat tetrahedral-mesh geometry was implemented in the particle and heavy ion transport code systems. To accelerate the computational speed in the transport process, an original algorithm was introduced to initially prepare decomposition maps for the container box of the tetrahedral-mesh geometry. Th...

journal_title：Physics in medicine and biology

authors： Furuta T,Sato T,Han MC,Yeom YS,Kim CH,Brown JL,Bolch WE

更新日期：2017-06-21 00:00:00

abstract：:The implementation of two algorithms for calculating dose distributions for radiation therapy treatment planning of intermediate energy proton beams is described. A pencil kernel algorithm and a depth penetration algorithm have been incorporated into a commercial three dimensional treatment planning system (Helax-TMS,...

journal_title：Physics in medicine and biology

authors： Russell KR,Isacsson U,Saxner M,Ahnesjö A,Montelius A,Grusell E,Dahlgren CV,Lorin S,Glimelius B

更新日期：2000-01-01 00:00:00

abstract：:The usefulness of a direct detection scheme of the second harmonic (2h) overmodulated signal from irradiated alanine in EPR dosimetry was studied. For this purpose, a group of DL-alanine/paraffin cylindrical pellets was produced. The dosimeters were irradiated with a 60Co radiotherapy gamma source with doses of 0.05, ...

journal_title：Physics in medicine and biology

authors： Chen F,Graeff CF,Baffa O

更新日期：2002-04-21 00:00:00

abstract：:Monte Carlo simulation provides a valuable tool in performance assessment and optimization of system design parameters for PET scanners. SimSET is a popular Monte Carlo simulation toolkit that features fast simulation time, as well as variance reduction tools to further enhance computational efficiency. However, SimSE...

journal_title：Physics in medicine and biology

authors： Poon JK,Dahlbom ML,Casey ME,Qi J,Cherry SR,Badawi RD

更新日期：2015-02-07 00:00:00

abstract：:The aim of this study was to measure entrance skin doses on patients undergoing cone-beam computed tomography (CBCT) examinations, to establish conversion factors between skin and organ doses, and to estimate cancer risk from CBCT exposures. 266 patients (age 8-83) were included, involving three imaging centres. CBCT ...

journal_title：Physics in medicine and biology

authors： Pauwels R,Cockmartin L,Ivanauskaité D,Urbonienė A,Gavala S,Donta C,Tsiklakis K,Jacobs R,Bosmans H,Bogaerts R,Horner K,SEDENTEXCT Project Consortium.

更新日期：2014-07-21 00:00:00

abstract：:Cell experiments have shown the proton relative biological effectiveness (RBE) to vary with dose and linear energy transfer (LET), which has led to development of variable RBE models. The RBE is normally estimated from two independent functions, the RBEmax and RBEmin, describing the extreme RBE at low and high doses. ...

journal_title：Physics in medicine and biology

authors： Rørvik E,Thörnqvist S,Ytre-Hauge KS

更新日期：2019-09-23 00:00:00

abstract：:Dielectric properties of porcine glandular tissues and gonads (in vivo) and body fluids (in vitro) have been obtained in the frequency range of 50 MHz to 20 GHz. The experimental data were fitted to a two term Cole-Cole expression. The data presented complement the available dielectric properties of tissues in the lit...

journal_title：Physics in medicine and biology

authors： Peyman A,Gabriel C

更新日期：2012-10-07 00:00:00