4D image reconstruction for emission tomography.

abstract：:We show that it is possible to translate an intensity modulated radiation therapy (IMRT) treatment plan and deliver it as a single arc. This technique is referred to in this paper as aperture modulation arc therapy (AMAT). During this arc, the MLC leaves do not conform to the projection of the target PTV and the machi...

journal_title：Physics in medicine and biology

authors： Crooks SM,Wu X,Takita C,Watzich M,Xing L

更新日期：2003-05-21 00:00:00

abstract：:Monte Carlo simulation of radiation transport is considered to be one of the most accurate methods of radiation therapy dose calculation. With the rapid development of computer technology, Monte Carlo based treatment planning for radiation therapy is becoming practical. A basic requirement for Monte Carlo treatment pl...

journal_title：Physics in medicine and biology

authors： Ma CM,Jiang SB

更新日期：1999-12-01 00:00:00

abstract：:The device developed by the authors and described here enables the user to measure the depth from the water surface to the point of measurement for a cylindrical ion chamber with a waterproof plastic cap in a water phantom, free of surface-tension error with a high precision. The device seeks vertical orientation and ...

journal_title：Physics in medicine and biology

authors： Tailor RC,Tello VM

更新日期：1995-08-01 00:00:00

abstract：:Usually, Monte Carlo models are validated against experimental data. However, models of multiple Coulomb scattering (MCS) in the Gaussian approximation are exceptional in that we have theories which are probably more accurate than the experiments which have, so far, been done to test them. In problems directly sensiti...

journal_title：Physics in medicine and biology

authors： Makarova A,Gottschalk B,Sauerwein W

更新日期：2017-07-06 00:00:00

abstract：:Several papers have recently addressed the issue of estimating chromophore concentration in optoacoustic imaging (OAI) using multiple wavelengths. The choice of wavelengths obviously affects the accuracy and precision of the estimates. One might assume that the wavelengths that maximize the extinction coefficients of ...

journal_title：Physics in medicine and biology

authors： Modgil D,La Riviére PJ

更新日期：2010-12-07 00:00:00

abstract：:This study aims at developing an optimization strategy for photon-beam dosimetry in magnetic fields using ionization chambers. Similar to the familiar case in the absence of a magnetic field, detectors should be selected under the criterion that their measured 2D signal profiles M(x,y) approximate the absorbed dose to...

journal_title：Physics in medicine and biology

authors： Looe HK,Delfs B,Poppinga D,Harder D,Poppe B

更新日期：2018-03-29 00:00:00

abstract：:The sensitivity and detection limit for measurements of the concentration of cadmium in the kidney cortex of man in vivo have been investigated using the technique of X-ray fluorescence. An 11 GB1 241Am source was used to generate the characteristic K alpha X-rays of cadmium. The variation in the sensitivity for the d...

journal_title：Physics in medicine and biology

authors： Ahlgren L,Mattsson S

更新日期：1981-01-01 00:00:00

abstract：:Magnetic resonance-guided radiation therapy (MR-GRT) offers great potential to improve radiation treatment outcomes by providing more accurate and patient-tailored therapy. Despite superior soft tissue contrast in MRI, one of the challenges towards MRI-only workflows is that the process often requires some sort of 'MR...

journal_title：Physics in medicine and biology

authors： Nosrati R,Paudel M,Ravi A,Pejovic-Milic A,Morton G,Stanisz GJ

更新日期：2019-07-16 00:00:00

abstract：:We study threshold-driven optimization methodology for automatically generating a treatment plan that is motivated by a reference DVH for IMRT treatment planning. We present a framework for threshold-driven optimization for reference-based auto-planning (TORA). Commonly used voxel-based quadratic penalties have two co...

journal_title：Physics in medicine and biology

authors： Long T,Chen M,Jiang S,Lu W

更新日期：2018-02-08 00:00:00

abstract：:The 50-year tenure of Physics in Medicine and Biology has coincided with some of the most important developments in radiological science, including the introduction of artificial radioactivity, computers and 3D imaging into medicine. These events have profoundly influenced the development of brachytherapy. Although it...

journal_title：Physics in medicine and biology

authors： Williamson JF

更新日期：2006-07-07 00:00:00

abstract：:In this paper, the influence of a dynamic variation in the ambient pressure on the subharmonic response of phospholipid-coated microbubbles was investigated. The ambient pressure in water was modulated by a 2.5 kHz acoustic wave with a peak amplitude of 15 kPa. We investigated the fundamental and subharmonic emissions...

journal_title：Physics in medicine and biology

authors： Faez T,Renaud G,Defontaine M,Calle S,de Jong N

更新日期：2011-10-07 00:00:00

abstract：:In (19)F MRI oximetry, a method used to image tumour hypoxia, perfluorocarbons serve as oxygenation markers. The goal of this study is to evaluate the impact of perfluorocarbon distribution and concentration in (19)F MRI oximetry through a computer simulation. The simulation studies the correspondence between (19)F me...

journal_title：Physics in medicine and biology

authors： Baete SH,Vandecasteele J,De Deene Y

更新日期：2011-04-21 00:00:00

abstract：:The architecture of multi-layer imagers (MLIs) can be exploited to provide megavoltage spectral imaging (MVSPI) for specific imaging tasks. In the current work, we investigated bone suppression and gold fiducial contrast enhancement as two clinical tasks which could be improved with spectral imaging. A method based on...

journal_title：Physics in medicine and biology

authors： Myronakis M,Hu YH,Fueglistaller R,Wang A,Baturin P,Huber P,Morf D,Star-Lack J,Berbeco R

更新日期：2018-05-10 00:00:00

abstract：:Intensive computation time is required to simulate images of electronic portal imaging device (EPID) using Monte Carlo (MC) technique, limiting the development of applications associated with EPID, such as mega-voltage cone-beam computed tomography (MV-CBCT). In this study, a fast, accurate simulation strategy for MV-...

journal_title：Physics in medicine and biology

authors： Shi M,Myronakis M,Jacobson M,Lehmann M,Ferguson D,Baturin P,Huber P,Fueglistaller R,Harris T,Lozano IV,Williams C,Morf D,Berbeco RI

更新日期：2020-07-06 00:00:00

abstract：:Accurate scatter correction is required to produce high-quality reconstructions of x-ray cone-beam computed tomography (CBCT) scans. This paper describes new scatter kernel superposition (SKS) algorithms for deconvolving scatter from projection data. The algorithms are designed to improve upon the conventional approac...

journal_title：Physics in medicine and biology

authors： Sun M,Star-Lack JM

更新日期：2010-11-21 00:00:00

abstract：:The purpose of this work is to provide an evaluation of the mean glandular dose (MGD) for breast computed tomography (CT) with synchrotron radiation in an axial scanning configuration with a partial or total organ volume irradiation, for the in vivo program of breast CT ongoing at the ELETTRA facility (Trieste, Italy)...

journal_title：Physics in medicine and biology

authors： Mettivier G,Fedon C,Di Lillo F,Longo R,Sarno A,Tromba G,Russo P

更新日期：2016-01-21 00:00:00

abstract：:The lipid disordering effect of aspirin on the liposomal membrane of dipalmitoyl phosphatidyl choline has recently been studied using the fluorescence polarization method. From the anisotropy-temperature curve, we have calculated here the associated change in van't Hoff enthalpy. Since the fluorescence technique requi...

journal_title：Physics in medicine and biology

authors： De S,Ghosh AK,Basu R,Nandy P

更新日期：1996-03-01 00:00:00

abstract：:Earlier work on the dielectric properties of cryoprotectant agents is extended using a modified measuring cell and method of data reduction yielding results more efficiently over a temperature range from -75 to +25 degrees C at frequencies from 27 MHz to 3 GHz. Dimethyl sulphoxide and butanediol are investigated at lo...

journal_title：Physics in medicine and biology

authors： Evans S,bin Azeman A

更新日期：1998-10-01 00:00:00

abstract：:Previously, readings of air-filled ionization chambers have been described as being influenced by magnetic fields. To use these chambers for dosimetry in magnetic resonance guided radiotherapy (MRgRT), this effect must be taken into account by introducing a correction factor k B. The purpose of this study is to system...

journal_title：Physics in medicine and biology

authors： Pojtinger S,Dohm OS,Kapsch RP,Thorwarth D

更新日期：2018-06-07 00:00:00

abstract：:A mathematical model has been constructed to simulate the response of cells in vitro to fractionated doses of radiation. The model is capable of describing most of the radiobiological functions that are commonly studied. Input data are measurable cell properties. The details of the model and methods of acquiring the i...

journal_title：Physics in medicine and biology

authors： Niederer J,Cunningham JR

更新日期：1976-09-01 00:00:00

abstract：:For the first time, three-dimensional images of the newborn infant brain have been generated using measurements of transmitted light. A 32-channel time-resolved imaging system was employed, and data were acquired using custom-made helmets which couple source fibres and detector bundles to the infant head. Images have ...

journal_title：Physics in medicine and biology

authors： Hebden JC,Gibson A,Yusof RM,Everdell N,Hillman EM,Delpy DT,Arridge SR,Austin T,Meek JH,Wyatt JS

更新日期：2002-12-07 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：:Managing uncertainty is a major challenge in radiation therapy treatment planning, including uncertainty induced by intrafraction motion, which is particularly important for tumours in the thorax and abdomen. Common methods to account for motion are to introduce a margin or to convolve the static dose distribution wit...

journal_title：Physics in medicine and biology

authors： Chan TC,Bortfeld T,Tsitsiklis JN

更新日期：2006-05-21 00:00:00

abstract：:Respiratory motion in emission tomography leads to reduced image quality. Developed correction methodology has been concentrating on the use of respiratory synchronized acquisitions leading to gated frames. Such frames, however, are of low signal-to-noise ratio as a result of containing reduced statistics. In this wor...

journal_title：Physics in medicine and biology

authors： Lamare F,Ledesma Carbayo MJ,Cresson T,Kontaxakis G,Santos A,Le Rest CC,Reader AJ,Visvikis D

更新日期：2007-09-07 00:00:00

abstract：:Dose calculations were performed for a tissue phantom irradiated by uniform circular beams of negative pions with an assumed gaussian momentum distribution. The mean momentum of the pions was varied from 104.4 to 171.5 MeV/c (mean range 5-20 cm in unit-density tissue) and the momentum spread from 0 to 5% of the mean. ...

journal_title：Physics in medicine and biology

authors： Hamm RN,Wright HA,Turner JE

更新日期：1979-05-01 00:00:00

abstract：:In this note a technique is described for direct aperture optimization of components deliverable by a variable aperture collimator (VAC) for intensity-modulated radiation therapy. The first key result found was that, provided a large number of VAC components were selected for optimization, the resulting fluence profil...

journal_title：Physics in medicine and biology

authors： Webb S

更新日期：2004-03-07 00:00:00

abstract：:A circular scanning trajectory is and will likely remain a popular choice of trajectory in computed tomography (CT) imaging because it is easy to implement and control. Filtered-backprojection (FBP)-based algorithms have been developed previously for approximate and exact reconstruction of the entire image or a region...

journal_title：Physics in medicine and biology

authors： Pan X,Xia D,Zou Y,Yu L

更新日期：2004-09-21 00:00:00

abstract：:Images of the human retina are routinely used in clinical practice for the diagnosis and management of eye disease. Increased permeability of retinal blood vessels, which is a clinically significant feature, can be visualized with a process known as fluorescein angiography as leakage of fluorescence dye into the surro...

journal_title：Physics in medicine and biology

authors： Cree MJ,Olson JA,McHardy KC,Sharp PF,Forrester JV

更新日期：1999-01-01 00:00:00

abstract：:Analytic solutions to the time-dependent multiregion bioheat equation are evaluated numerically for cartesian and spherical models. Principle and alternate branch contributions to the solutions are examined. The calculations include a parametric investigation and analyses of temperature behaviour in idealised upper th...

journal_title：Physics in medicine and biology

authors： Durkee JW Jr,Antich PP,Lee CE

更新日期：1990-07-01 00:00:00

abstract：:Users of nuclear and atomic data for biomedical purposes often have difficulty in identifying the most up-to-date and appropriate sources of such data. The biomedical Subcommittee of the UK Nuclear Data Committee have prepared a list of recommended data sources available at the beginning of 1978 on radioactive decay s...

journal_title：Physics in medicine and biology

authors： Holt PD

更新日期：1979-01-01 00:00:00