Comparative efficiency of the multi-leaf collimator and variable-aperture collimator in intensity-modulated radiotherapy.

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：:Spreadsheet templates which calculate cumulative exposures to other persons from patients to whom radioactive materials have been administered have been developed by the authors. Calculations can be based on any specified single-, bi- or tri-exponential whole-body clearance rate and a diurnal (or any other periodic) c...

journal_title：Physics in medicine and biology

authors： Cormack J,Shearer J

更新日期：1998-03-01 00:00:00

abstract：:In the field of regenerative medicine, there has been a growing interest in studying the combination of bone scaffolds and cells that can maximize newly formed bone. In-line phase-contrast x-ray tomography was used to image porous bone scaffolds (Skelite(©)), seeded with bone forming cells. This technique allows the q...

journal_title：Physics in medicine and biology

authors： Weber L,Langer M,Tavella S,Ruggiu A,Peyrin F

更新日期：2016-05-07 00:00:00

abstract：:Quantification in cardiac mouse positron emission tomography (PET) imaging is limited by the imaging spatial resolution. Spillover of left ventricle (LV) myocardial activity into adjacent organs results in partial volume (PV) losses leading to underestimation of myocardial activity. A PV correction method was develope...

journal_title：Physics in medicine and biology

authors： Dumouchel T,Thorn S,Kordos M,DaSilva J,Beanlands RS,deKemp RA

更新日期：2012-07-07 00:00:00

abstract：:Treatment plans optimized for intensity modulated proton therapy (IMPT) may be sensitive to range variations. The dose distribution may deteriorate substantially when the actual range of a pencil beam does not match the assumed range. We present two treatment planning concepts for IMPT which incorporate range uncertai...

journal_title：Physics in medicine and biology

authors： Unkelbach J,Chan TC,Bortfeld T

更新日期：2007-05-21 00:00:00

abstract：:Although physical metrics can objectively characterize computed tomography (CT) image quality, quantitative approaches to predict human observer performance are more accurate and clinically relevant. This study compared a modified channelized Hotelling model observer (CHO) with human observers in a shape discriminatio...

journal_title：Physics in medicine and biology

authors： Zhang Y,Leng S,Yu L,Carter RE,McCollough CH

更新日期：2014-07-07 00:00:00

abstract：:The effect of the physical state (phase) of the absorbing medium and the energy straggling of the alpha particles on the calculation of the radiation dose due to the daughter products of radon deposited in the lung have been studied in detail. The stopping power data for alpha particles in water and water vapour have ...

journal_title：Physics in medicine and biology

authors： Haque AK,Al-affan IA

更新日期：1987-08-01 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：:In stereotactic radiosurgery, a seven-irradiation film was used to define any discrepancy between the beam and target centres. A mathematical model based on the linac alignment and target set-up was developed to diagnose the discrepancies of the seven-irradiation film between the beam and simulation target centres. Fr...

journal_title：Physics in medicine and biology

authors： Tsai JS

更新日期：1996-09-01 00:00:00

abstract：:In this paper, we have investigated the feasibility of imaging the mechanical behavior of poroelastic materials using axial strain elastography. Cylindrical samples obtained from poroelastic materials having different elastic and permeability properties were subjected to a constant compression force (a classical creep...

journal_title：Physics in medicine and biology

authors： Righetti R,Righetti M,Ophir J,Krouskop TA

更新日期：2007-06-07 00:00:00

abstract：:Blood was withdrawn from the ante-cubital vein of five normal volunteers and the erythrocytes were washed and resuspended in isotonic saline. The rate of descent of the erythrocyte-saline boundary was measured every hour for a period of at least 4 h for different suspended cell concentrations. The velocity of this bou...

journal_title：Physics in medicine and biology

authors： Smallwood RH,Tindale WB,Trowbridge EA

更新日期：1985-02-01 00:00:00

abstract：:The Akaike information criterion and the associated Akaike weights (AW) rank pharmacokinetic models on the basis of goodness-of-fit and number of parameters. The usefulness of this information for improving the haemodynamic parameter estimates from DCE-MRI was investigated through two examples. In each of these, the e...

journal_title：Physics in medicine and biology

authors： Luypaert R,Ingrisch M,Sourbron S,de Mey J

更新日期：2012-06-07 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：:We study the treatment plan optimization problem for volumetric modulated arc therapy (VMAT). We propose a new column-generation-based algorithm that takes into account bounds on the gantry speed and dose rate, as well as an upper bound on the rate of change of the gantry speed, in addition to MLC constraints. The alg...

journal_title：Physics in medicine and biology

authors： Peng F,Jia X,Gu X,Epelman MA,Romeijn HE,Jiang SB

更新日期：2012-07-21 00:00:00

abstract：:Radiochromic films are useful as dosimeters in high-precision radiotherapy owing to their high spatial resolution. However, when a particle beam is measured using a radiochromic film, the dose cannot be estimated accurately because the film darkness varies with variations in linear energy transfer (LET). This paper pr...

journal_title：Physics in medicine and biology

authors： Kawashima M,Matsumura A,Souda H,Tashiro M

更新日期：2020-06-15 00:00:00

abstract：:Simulation of small-angle x-ray scattering from collagen in healthy and cancerous breast tissue may reveal detailed information on the structural changes in collagen. Collagen fibril is modelled as a cylinder with axially periodic step-function electron density, and packing is approximated by placing the cylinders in ...

journal_title：Physics in medicine and biology

authors： Suhonen H,Fernández M,Serimaa R,Suortti P

更新日期：2005-11-21 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：:A variable Jacobian and weighted backprojection algorithm, used for medical CT, was adapted to perform CT reconstructions on data obtained with a dental panoramic x-ray unit. A detector array, fitted to the unit for the purpose of acquiring digital panoramic radiographs, was used to collect the data. Compensations wer...

journal_title：Physics in medicine and biology

authors： Lee MD,Waggener RG,McDavid WD,Dove SB,Welander U,Tronje G

更新日期：1992-12-01 00:00:00

abstract：:The probability of a photon (x-ray, gamma-ray, bremsstrahlung, etc) of a given energy E undergoing absorption or scattering when traversing a layer of material Z can be expressed quantitatively in terms of a linear attenuation coefficient mu (cm(-1)). Since mu is dependent on the material's density, rho (g cm(-3)), wh...

journal_title：Physics in medicine and biology

authors： Hubbell JH

更新日期：1999-01-01 00:00:00

abstract：:Plutonium-239 and americium-241 were administered to adult hamsters in various chemical forms and their absorption from the gut was measured. The results have been compared with published data on other species in order to derive values for the estimated absorption of these actinides in man. On the basis of current kno...

journal_title：Physics in medicine and biology

authors： Stather JW,Harrison JD,Rodwell P,David AJ

更新日期：1979-03-01 00:00:00

abstract：:Ultrasound current source density imaging (UCSDI) exploits the acoustoelectric (AE) effect, an interaction between ultrasound pressure and electrical resistivity, to map electrical conduction in the heart. The conversion efficiency for UCSDI is determined by the AE interaction constant K, a fundamental property of all...

journal_title：Physics in medicine and biology

authors： Li Q,Olafsson R,Ingram P,Wang Z,Witte R

更新日期：2012-10-07 00:00:00

abstract：:Sparse-view CT reconstruction algorithms via total variation (TV) optimize the data iteratively on the basis of a noise- and artifact-reducing model, resulting in significant radiation dose reduction while maintaining image quality. However, the piecewise constant assumption of TV minimization often leads to the appea...

journal_title：Physics in medicine and biology

authors： Niu S,Gao Y,Bian Z,Huang J,Chen W,Yu G,Liang Z,Ma J

更新日期：2014-06-21 00:00:00

abstract：:A new mathematical model of the head has been constructed from a set of serial MRI slices from one subject. Finite-difference time-domain (FDTD) calculations of the specific energy absorption rate (SAR) have been performed on this model with a 2 mm resolution for a generic mobile communication transceiver represented ...

journal_title：Physics in medicine and biology

authors： Dimbylow PJ,Mann SM

更新日期：1994-10-01 00:00:00

abstract：:The optical properties (absorption and scattering coefficients and the scattering anisotropy factor) were measured in vitro for cartilage, liver, lung, muscle, myocardium, skin, and tumour (colon adenocarcinoma CC 531) at 630, 632.8, 790, 850 and 1064 nm. Rabbits, rats, piglets, goats, and dogs were used to obtain the...

journal_title：Physics in medicine and biology

authors： Beek JF,Blokland P,Posthumus P,Aalders M,Pickering JW,Sterenborg HJ,van Gemert MJ

更新日期：1997-11-01 00:00:00

abstract：:X-ray scatter is a significant problem in cone-beam computed tomography when thicker objects and larger cone angles are used, as scattered radiation can lead to reduced contrast and CT number inaccuracy. Advances have been made in x-ray computed tomography (CT) by incorporating a high quality prior image into the imag...

journal_title：Physics in medicine and biology

authors： Brunner S,Nett BE,Tolakanahalli R,Chen GH

更新日期：2011-02-21 00:00:00

abstract：:The widely applied single-interaction analytic expression characterizing the energy resolution component of the angular resolution precision for an electronically collimated point source is extended to include multiple-interaction Compton scatter sequences as well as sequences terminated by photoelectric absorption. T...

journal_title：Physics in medicine and biology

authors： Durkee JW Jr,Antich PP,Tsyganov EN,Constantinescu A,Kulkarni PV,Smith BJ,Arbique GM,Lewis MA,Nguyen T,Raheja A,Thambi G,Parkey RW

更新日期：1998-10-01 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：:Many models exist for predicting toxicities based on dose-volume histograms (DVHs) or dose-surface histograms (DSHs). This approach has several drawbacks as firstly the reduction of the dose distribution to a histogram results in the loss of spatial information and secondly the bins of the histograms are highly correl...

journal_title：Physics in medicine and biology

authors： Buettner F,Gulliford SL,Webb S,Partridge M

更新日期：2011-04-07 00:00:00

abstract：:The signal properties of polycrystalline mercuric iodide (HgI2) film detectors, under irradiation conditions relevant to mammographic, radiographic, fluoroscopic and radiotherapy x-ray imaging, are reported. Each film detector consists of an approximately 230 to approximately 460 microm thick layer of HgI2 (fabricated...

journal_title：Physics in medicine and biology

authors： Su Z,Antonuk LE,El-Mohri Y,Hu L,Du H,Sawant A,Li Y,Wang Y,Yamamoto J,Zhao Q

更新日期：2005-06-21 00:00:00

abstract：:We propose a novel scintillation detector design for positron emission tomography (PET), which has depth of interaction (DOI) capability and uses a single-ended readout scheme. The DOI detector contains a pair of crystal bars segmented using sub-surface laser engraving (SSLE). The two crystal bars are optically couple...

journal_title：Physics in medicine and biology

authors： Uchida H,Sakai T,Yamauchi H,Hakamata K,Shimizu K,Yamashita T

更新日期：2016-09-21 00:00:00