Integral equations and boundary-element solution for static potential in a general piece-wise homogeneous volume conductor.

abstract：:We present a method to include robustness in a multi-criteria optimization (MCO) framework for intensity-modulated proton therapy (IMPT). The approach allows one to simultaneously explore the trade-off between different objectives as well as the trade-off between robustness and nominal plan quality. In MCO, a database...

journal_title：Physics in medicine and biology

authors： Chen W,Unkelbach J,Trofimov A,Madden T,Kooy H,Bortfeld T,Craft D

更新日期：2012-02-07 00:00:00

abstract：:Quantifying the retention or washout of (99m)Tc-Sestamibi (MIBI) in breast tumours in vivo may provide a basis for predicting the chemotherapy response. The aim of this study is to investigate the variations and limitations of the different methods used to quantify these parameters. A phantom was developed that allowe...

journal_title：Physics in medicine and biology

authors： Marshall C,Griffiths PA

更新日期：2005-05-07 00:00:00

abstract：:An inflatable endorectal balloon (ERB) is often used during stereotactic body radiation therapy (SBRT) for treatment of prostate cancer in order to reduce both intrafraction motion of the target and risk of rectal toxicity. However, the ERB can exert significant force on the prostate, and this work assessed the impact...

journal_title：Physics in medicine and biology

authors： Jones BL,Gan G,Kavanagh B,Miften M

更新日期：2013-11-21 00:00:00

abstract：:A method for quantifying the tissue sodium concentration (TSC) in the rat brain from ²³Na-MR images was developed. TSC is known to change in a variety of common human diseases and holds considerable potential to contribute to their study; however, its accurate measurement in small laboratory animals has been hindered ...

journal_title：Physics in medicine and biology

authors： Wetterling F,Tabbert M,Junge S,Gallagher L,Macrae IM,Fagan AJ

更新日期：2010-12-21 00:00:00

abstract：:A technique is described for examining the mode of operation of radiation detectors and estimating the losses and gains caused by random summing effects in spectra acquired at high counting rates. The technique is applied to estimating the errors caused by random summing when measuring the amounts of carbon and nitrog...

journal_title：Physics in medicine and biology

authors： Yankuba S,Oldroyd B,Metcalfe SC,Godfrey JE,Oxby CB

更新日期：1989-08-01 00:00:00

abstract：:Avoiding toxicities in radiotherapy requires the knowledge of tolerable organ doses. For new, experimental fractionation schemes (e.g. hypofractionation) these are typically derived from traditional schedules using the biologically effective dose (BED) model. In this report we investigate the difficulties of establish...

journal_title：Physics in medicine and biology

authors： Perkó Z,Bortfeld T,Hong T,Wolfgang J,Unkelbach J

更新日期：2018-02-05 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：: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：:Beta emitting 106Ru-applicators are used to treat choroidal melanoma. In order to improve the accuracy and simplify the dosimetry of these applicators, the suitability of using a p-type silicon semiconductor detector has been investigated. The detector is calibrated in a low energy electron beam. An important property...

journal_title：Physics in medicine and biology

authors： Lax I

更新日期：1991-07-01 00:00:00

abstract：:The UMC Utrecht is constructing a 1.5 T MRI scanner integrated with a linear accelerator (Lagendijk et al 2008 Radiother. Oncol. 86 25-9). The goal of this device is to facilitate soft-tissue contrast based image-guided radiotherapy, in order to escalate the dose to the tumour while sparing surrounding normal tissues....

journal_title：Physics in medicine and biology

authors： Meijsing I,Raaymakers BW,Raaijmakers AJ,Kok JG,Hogeweg L,Liu B,Lagendijk JJ

更新日期：2009-05-21 00:00:00

abstract：:A three-dimensional spherical inclusion model that approximates a lesion bonded to a tissue matrix is proposed for biomedical elastography. Analytical formulae describing spatial strain and stress distributions generated in infinite media by uniform loading are given under a linear, homogeneous, isotropic elasticity a...

journal_title：Physics in medicine and biology

authors： Bilgen M,Insana MF

更新日期：1998-01-01 00:00:00

abstract：:The effect of temperature on the optical properties of human dermis and subdermis as a function of near-infrared wavelength has been studied between 25 degrees C and 40 degrees C. Measurements were performed ex vivo on a total of nine skin samples taken from the abdomen of three individuals. The results show a reprodu...

journal_title：Physics in medicine and biology

authors： Laufer J,Simpson R,Kohl M,Essenpreis M,Cope M

更新日期：1998-09-01 00:00:00

abstract：:Identification of prostate gold fiducial markers in magnetic resonance imaging (MRI) images is challenging when CT images are not available, due to misclassifications from intra-prostatic calcifications. It is also a time consuming task and automated identification methods have been suggested as an improvement for bot...

journal_title：Physics in medicine and biology

authors： Gustafsson CJ,Swärd J,Adalbjörnsson SI,Jakobsson A,Olsson LE

更新日期：2020-11-12 00:00:00

abstract：:Large blood vessels can produce steep temperature gradients in heated tissues leading to inadequate tissue temperatures during hyperthermia. This paper utilizes a finite difference scheme to solve the basic equations of heat transfer and fluid flow to model blood vessel cooling. Unlike previous formulations, heat tran...

journal_title：Physics in medicine and biology

authors： Kolios MC,Sherar MD,Hunt JW

更新日期：1995-04-01 00:00:00

abstract：:We present an automatic bi-objective parameter-tuning approach for inverse planning methods for high-dose-rate prostate brachytherapy, which aims to overcome the difficult and time-consuming manual parameter tuning that is currently required to obtain patient-specific high-quality treatment plans. We modelled treatmen...

journal_title：Physics in medicine and biology

authors： Maree SC,Bosman PAN,van Wieringen N,Niatsetski Y,Pieters BR,Bel A,Alderliesten T

更新日期：2020-04-02 00:00:00

abstract：:Input functions required for positron emission tomography (PET) tracer kinetic modeling are often obtained from arterial blood. In some situations, using short-lived radiotracers, e.g. [(15)O]water, rapid sample handling is required. A method used at several facilities is to pump blood through a detector system at a c...

journal_title：Physics in medicine and biology

authors： Laymon CM,Sashin D,Carney JP,Ruszkiewicz J,Altenburger D,Becker CR,Lopresti BJ,Mason NS,Mountz JM,Price JC,Schavey R,Mathis CA

更新日期：2008-01-21 00:00:00

abstract：:Instead of performing a numerical deconvolution, we propose to use a linear piecewise-continuous model of the renal impulse response function for parametric fitting of renal scintigraphy data, to obtain clinically useful renal parameters. The strengths of the present model are its simplicity and speed of computation, ...

journal_title：Physics in medicine and biology

authors： Zhang JL,Zhang L,Koh TS,Shuter B

更新日期：2003-06-21 00:00:00

abstract：:None of the existing protocols or codes of practice for high-energy electron dosimetry take any account of the accelerator-generated bremsstrahlung always present in electron beams. This results in a systematic error in the derivation of the absorbed dose. The purpose of this study is to draw attention to this omissio...

journal_title：Physics in medicine and biology

authors： Klevenhagen SC

更新日期：1994-07-01 00:00:00

abstract：:This work is dedicated to the reduction of reconstruction artefacts due to motion occurring during the acquisition of computerized tomographic projections. This problem has to be solved when imaging moving organs such as the lungs or the heart. The proposed method belongs to the class of motion compensation algorithms...

journal_title：Physics in medicine and biology

authors： Roux S,Desbat L,Koenig A,Grangeat P

更新日期：2004-06-07 00:00:00

abstract：:Irreversible electroporation (IRE) is a minimally invasive tumor therapy using pulsed electric field with high intensity while the important tissues such as blood vessel, bile duct, and nerve are preserved. In addition to ablation area, reversible electroporation (RE) region is also generated using needle electrodes f...

journal_title：Physics in medicine and biology

authors： Lv Y,Tang X,Peng W,Cheng X,Chen S,Yao C

更新日期：2020-10-14 00:00:00

abstract：:The purpose of this study was to develop a method to simulate breathing motion induced interplay effects for volumetric modulated arc therapy (VMAT), to verify the proposed method with measurements, and to use the method to investigate how interplay effects vary with different patient- and machine specific parameters....

journal_title：Physics in medicine and biology

authors： Edvardsson A,Nordström F,Ceberg C,Ceberg S

更新日期：2018-04-19 00:00:00

abstract：:Breast cancer is one of the leading causes of female cancer deaths. Early diagnosis with prophylactic may improve the patients' prognosis. So far ultrasound (US) imaging is a popular method in breast cancer diagnosis. However, its accuracy is bounded to traditional handcrafted feature methods and expertise. A novel me...

journal_title：Physics in medicine and biology

authors： Xie J,Song X,Zhang W,Dong Q,Wang Y,Li F,Wan C

更新日期：2020-10-29 00:00:00

abstract：:A Monte Carlo computational model of a fluoroscopic imaging chain was used for deriving optimal technique factors for paediatric fluoroscopy. The optimal technique was defined as the one that minimizes the absorbed dose (or dose rate) in the patient with a constraint of constant image quality. Image quality was assess...

journal_title：Physics in medicine and biology

authors： Tapiovaara MJ,Sandborg M,Dance DR

更新日期：1999-02-01 00:00:00

abstract：:The characteristics of an Elekta Precise treatment machine with a gating interface were investigated. Three detectors were used: a Farmer ionization chamber, a MatriXX ionization chamber array and an in-house, single pulse-measurement ionization chamber (IVC). Measurements were made of dosimetric accuracy, flatness an...

journal_title：Physics in medicine and biology

authors： Evans PM,Symonds-Tayler JR,Colgan R,Hugo GD,Letts N,Sandin C

更新日期：2010-04-21 00:00:00

abstract：:Multileaf collimator (MLC) calibration and quality control is a time-consuming procedure typically involving the processing, scanning and analysis of films to measure leaf and collimator positions. Faster and more reliable calibration procedures are required for these tasks, especially with the introduction of intensi...

journal_title：Physics in medicine and biology

authors： Baker SJ,Budgell GJ,MacKay RI

更新日期：2005-04-07 00:00:00

abstract：:Source anisotropy is a very important factor in the brachytherapy quality assurance of high-dose rate (HDR) 192Ir afterloading stepping sources. If anisotropy is not taken into account then doses received by a brachytherapy patient in certain directions can be in error by a clinically significant amount. Experimental ...

journal_title：Physics in medicine and biology

authors： Baltas D,Giannouli S,Garbi A,Diakonos F,Geramani K,Ioannidis GT,Tsalpatouros A,Uzunoglu N,Kolotas C,Zamboglou N

更新日期：1998-06-01 00:00:00

abstract：:We describe an improved algorithm for localising equivalent sources of biomagnetic fields in the human brain. The algorithm is an improvement over the sphere model in that it considers two distinct surfaces: an ellipsoid, to model the region of the skull on which the sensors are placed, and a sphere as the medium in w...

journal_title：Physics in medicine and biology

authors： Pistella F,Barone P,Narici L,Ocello N,Pizzella V,Romani GL

更新日期：1987-01-01 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：:Wafer-scale CMOS active pixel sensors (APSs) have been developed recently for x-ray imaging applications. The small pixel pitch and low noise are very promising properties for medical imaging applications such as digital breast tomosynthesis (DBT). In this work, we evaluated experimentally and through modeling the ima...

journal_title：Physics in medicine and biology

authors： Zhao C,Konstantinidis AC,Zheng Y,Anaxagoras T,Speller RD,Kanicki J

更新日期：2015-12-07 00:00:00

abstract：:Mean glandular dose (MGD) is the figure of merit to assess breast dose after a mammographic acquisition. The use of normalized MGD obtained from Monte Carlo computations with measured incident air kerma determines the MGD delivered to patients. The Geant4 Application for Tomographic Emission (GATE) toolkit is a modern...

journal_title：Physics in medicine and biology

authors： Myronakis ME,Zvelebil M,Darambara DG

更新日期：2013-04-07 00:00:00