Coupled radiative transfer equation and diffusion approximation model for photon migration in turbid medium with low-scattering and non-scattering regions.

abstract：:The low energy model of the GEANT4 Monte Carlo toolkit was used to simulate the energy response of a T.P.A. Mk-II ionization chamber under a variety of different conditions. The sample position resulting in the maximum response along the axial direction of the chamber was obtained. The parameters of the simulation wer...

journal_title：Physics in medicine and biology

authors： Seneviratne MD,Reinhard MI,Baldock C

更新日期：2007-07-07 00:00:00

abstract：:Average cross-sections for inactivation of dry ribonuclease by H, He and N projectiles with energies between 100 eV and 10 keV are presented. The trend of the damage cross-sections with particle energy is consistent with the trend of the molecular quasi-elastic scattering and ionization cross-sections. A tentative rad...

journal_title：Physics in medicine and biology

authors： Watt DE,Sutcliffe JF

更新日期：1975-11-01 00:00:00

abstract：:A 4D ordered-subsets maximum a posteriori (OSMAP) algorithm for dynamic SPECT is described which uses a temporal prior that constrains each voxel's behaviour in time to conform to a compartmental model. No a priori limitations on kinetic parameters are applied; rather, the parameter estimates evolve as the algorithm i...

journal_title：Physics in medicine and biology

authors： Kadrmas DJ,Gullberg GT

更新日期：2001-05-01 00:00:00

abstract：:The feasibility is demonstrated of a numerical method to calculate dose deposition by broad high-energy electron beams in homogeneous matter or in heterogeneous matter in which the heterogeneities are arranged in slabs perpendicular to the beam axis. The method is based only on the basic physical interaction processes...

journal_title：Physics in medicine and biology

authors： Huizenga H,Storchi PR

更新日期：1989-10-01 00:00:00

abstract：:The design, construction and use of a large-scale field-cycled proton-electron double-resonance imaging (FC-PEDRI) imager is described. The imager is based on a whole-body sized, vertical field, 59 mT permanent magnet. Field cycling is accomplished by the field compensation method, and uses a secondary, resistive magn...

journal_title：Physics in medicine and biology

authors： Lurie DJ,Foster MA,Yeung D,Hutchison JM

更新日期：1998-07-01 00:00:00

abstract：:Proton beams used for radiotherapy will produce neutrons when interacting with matter. The purpose of this study was to quantify the equivalent dose to tissue due to secondary neutrons in pediatric and adult patients treated by proton therapy for brain lesions. Assessment of the equivalent dose to organs away from the...

journal_title：Physics in medicine and biology

authors： Zacharatou Jarlskog C,Lee C,Bolch WE,Xu XG,Paganetti H

更新日期：2008-02-07 00:00:00

abstract：:Megavoltage (MV) cone-beam computed tomography (CBCT) using an electronic portal imaging (EPID) offers advantageous features, including 3D mapping, treatment beam registration, high-z artifact suppression, and direct radiation dose calculation. Adoption has been slowed by image quality limitations and concerns about i...

journal_title：Physics in medicine and biology

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

更新日期：2018-06-20 00:00:00

abstract：:Cavity theories are used to relate the dose in a medium to the dose in a cavity. No satisfactory analytical approach exists for the case of intermediate cavities, such as TLDs, when interface effects are important. Burlin proposed a general cavity theory that accounts for the cavity size but which ignores interface ef...

journal_title：Physics in medicine and biology

authors： Frujinoiu C

更新日期：2001-04-01 00:00:00

abstract：:Models of the electrical properties of biological tissue have been the subject of many studies. These models have sought to explain aspects of the dielectric dispersion of tissue. This paper develops a mathematical model of the complex permittivity of tissue as a function of frequency f, in the range 10(4) < f < 10(7)...

journal_title：Physics in medicine and biology

authors： Smye SW,Evans CJ,Robinson MP,Sleeman BD

更新日期：2007-12-07 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：:All available imaging devices in nuclear medicine have finite energy resolution. This leads to inclusion of scattered radiation, which in turn degrades the image quality. Different scatter correction schemes therefore try to eliminate the effect of scattered radiation. On the other hand, improvement of the camera's in...

journal_title：Physics in medicine and biology

authors： Wirth V

更新日期：1989-01-01 00:00:00

abstract：:Noise equivalent count rate (NECR) and image noise are two different but related metrics that have been used to predict and assess image quality, respectively. The aim of this study is to investigate, using patient studies, the relationships between injected dose (ID), body mass index (BMI) and scanner type on NECR an...

journal_title：Physics in medicine and biology

authors： Chang T,Chang G,Kohlmyer S,Clark JW,Rohren E,Mawlawi OR

更新日期：2011-08-21 00:00:00

abstract：:This paper presents a method to obtain the pencil-beam kernels that characterize a megavoltage photon beam generated in a flattening filter free (FFF) linear accelerator (linac) by deconvolution from experimental measurements at different depths. The formalism is applied to perform independent dose calculations in mod...

journal_title：Physics in medicine and biology

authors： Azcona JD,Barbés B,Wang L,Burguete J

更新日期：2016-01-07 00:00:00

abstract：:Recent acute shortage of medical radioisotopes prompted investigations into alternative methods of production and the use of a cyclotron and ¹⁰⁰Mo(p,2n)(99m)Tc reaction has been considered. In this context, the production yields of (99m)Tc and various other radioactive and stable isotopes which will be created in the ...

journal_title：Physics in medicine and biology

authors： Celler A,Hou X,Bénard F,Ruth T

更新日期：2011-09-07 00:00:00

abstract：:Numerous studies of early-stage breast cancer treated with breast conserving surgery (BCS) and radiotherapy (RT) have been published in recent years. Both external beam radiotherapy (EBRT) and/or brachytherapy (BT) with different fractionation schemes are currently used. The present RT practice is largely based on emp...

journal_title：Physics in medicine and biology

authors： Guerrero M,Li XA

更新日期：2003-10-21 00:00:00

abstract：:Monte Carlo simulation with PENELOPE (version 2003) is applied to calculate Leksell Gamma Knife dose distributions for heterogeneous phantoms. The usual spherical water phantom is modified with a spherical bone shell simulating the skull and an air-filled cube simulating the frontal or maxillary sinuses. Different sim...

journal_title：Physics in medicine and biology

authors： Al-Dweri FM,Rojas EL,Lallena AM

更新日期：2005-12-07 00:00:00

abstract：:The least known parameters in a Monte Carlo simulation of a linear accelerator treatment head are often the properties of the initial electron beam directed onto the exit vacuum window. Several initial beams with different spatial fluence distributions, angular divergences and energy spectra have been transported thro...

journal_title：Physics in medicine and biology

authors： Björk P,Knöös T,Nilsson P

更新日期：2002-11-21 00:00:00

abstract：:The metabolic content of urine from NIH III nude mice (n = 22) was analysed before and after inoculation with human glioblastoma multiforme (GBM) cancer cells. An age- and gender-matched control population (n = 14) was also studied to identify non-tumour-related changes. Urine samples were collected daily for 6 weeks,...

journal_title：Physics in medicine and biology

authors： Moroz J,Turner J,Slupsky C,Fallone G,Syme A

更新日期：2011-02-07 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：:Distributions of linear pathlength measurements have been utilized in skeletal dosimetry of internally emitted short-range particles for over 30 years. This work reviews the methods for coupling these distributions to range-energy data. A revised methodology is presented for handling the insertion of the additional do...

journal_title：Physics in medicine and biology

authors： Jokisch DW,Rajon DA,Patton PW,Bolch WE

更新日期：2011-05-07 00:00:00

abstract：:Prompt gamma (PG) imaging is widely investigated for spot-by-spot in vivo range verification for proton therapy. Previous studies pointed out that the accuracy of prompt gamma imaging is affected by the statistics (number of protons delivered per pencil beam) of the proton beams and the conformity between prompt gamma...

journal_title：Physics in medicine and biology

authors： Tian L,Landry G,Dedes G,Pinto M,Kamp F,Belka C,Parodi K

更新日期：2020-04-29 00:00:00

abstract：:Although interventional x-ray angiography (XA) procedures involve relatively high radiation doses that can lead to deterministic tissue reactions in addition to stochastic effects, convenient and accurate estimation of absorbed organ doses has traditionally been out of reach. This has mainly been due to the absence of...

journal_title：Physics in medicine and biology

authors： Omar A,Bujila R,Fransson A,Andreo P,Poludniowski G

更新日期：2016-04-21 00:00:00

abstract：:The purpose of this study is the analysis of the influence of anisotropic conductivity on magnetic fields and electric potentials by means of phantom measurements. An artificial rotating current dipole was placed in the middle of an anisotropic skein arrangement in a torso phantom filled with saline solution. The sign...

journal_title：Physics in medicine and biology

authors： Liehr M,Haueisen J

更新日期：2008-01-07 00:00:00

abstract：:Computational phantoms are commonly used in internal radiation dosimetry to assess the amount and distribution pattern of energy deposited in various parts of the human body from different internal radiation sources. Radiation dose assessments are commonly performed on predetermined reference computational phantoms wh...

journal_title：Physics in medicine and biology

authors： Xie T,Kuster N,Zaidi H

更新日期：2017-07-13 00:00:00

abstract：:A new component module (CM), designated DYNVMLC, was developed to fully model the geometry of the Varian Millennium 120 leaf collimator using the BEAMnrc Monte Carlo code. The model includes details such as the leaf driving screw hole, support railing groove and leaf tips. Further modifications also allow sampling of ...

journal_title：Physics in medicine and biology

authors： Heath E,Seuntjens J

更新日期：2003-12-21 00:00:00

abstract：:We couple standardized low-resolution electromagnetic tomography, an inverse solution for electroencephalography (EEG) and the common spatial pattern, which is here conceived as a data-driven beamformer, to classify the benchmark BCI (brain-computer interface) competition 2003, data set IV. The data set is from an exp...

journal_title：Physics in medicine and biology

authors： Congedo M,Lotte F,Lécuyer A

更新日期：2006-04-21 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：:Cardiac and respiratory motion artefacts in PET imaging have been traditionally resolved by acquiring the data in gated mode. However, gated PET images are usually characterized by high noise content due to their low photon statistics. In this paper, we present a novel 4D model for the PET imaging system, which can in...

journal_title：Physics in medicine and biology

authors： Qiao F,Pan T,Clark JW Jr,Mawlawi OR

更新日期：2006-08-07 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：:Segmentation of liver in abdominal computed tomography (CT) is an important step for radiation therapy planning of hepatocellular carcinoma. Practically, a fully automatic segmentation of liver remains challenging because of low soft tissue contrast between liver and its surrounding organs, and its highly deformable s...

journal_title：Physics in medicine and biology

authors： Qin W,Wu J,Han F,Yuan Y,Zhao W,Ibragimov B,Gu J,Xing L

更新日期：2018-05-04 00:00:00