Analysis of RF exposure in the head tissues of children and adults.

abstract：:Diffusion weighted magnetic resonance imaging offers a non-invasive tool to explore the three-dimensional structure of brain white matter in clinical practice. Anisotropic diffusion hardware phantoms are useful for the quantitative validation of this technique. This study provides guidelines on how to manufacture anis...

journal_title：Physics in medicine and biology

authors： Fieremans E,De Deene Y,Delputte S,Ozdemir MS,Achten E,Lemahieu I

更新日期：2008-10-07 00:00:00

abstract：:Computer tomographic (CT) scans are used to correct for tissue inhomogeneities in radiotherapy treatment planning. In order to guarantee a precise treatment, it is important to obtain the relationship between CT Hounsfield units and electron densities (or proton stopping powers for proton radiotherapy), which is the b...

journal_title：Physics in medicine and biology

authors： Schneider U,Pedroni E,Lomax A

更新日期：1996-01-01 00:00:00

abstract：:A multimodal micro-computed tomography (CT) and multi-spectral structured light imaging (SLI) system is introduced and systematically analyzed to test its feasibility to aid in margin delineation during breast conserving surgery (BCS). Phantom analysis of the micro-CT yielded a signal-to-noise ratio of 34, a contrast ...

journal_title：Physics in medicine and biology

authors： McClatchy DM,Rizzo EJ,Meganck J,Kempner J,Vicory J,Wells WA,Paulsen KD,Pogue BW

更新日期：2017-11-10 00:00:00

abstract：:The signal-to-noise ratio (SNR) in x-ray imaging can be increased using a photon counting detector which could allow for rejecting electronics noise and for weighting x-ray photons according to their energies. This approach, however, was not feasible for a long time because photon counting x-ray detectors with very hi...

journal_title：Physics in medicine and biology

authors： Shikhaliev PM

更新日期：2009-08-21 00:00:00

abstract：:The bone suppression technique based on advanced image processing can suppress the conspicuity of bones on chest radiographs, creating soft tissue images obtained by the dual-energy subtraction technique. This study was performed to evaluate the usefulness of bone suppression image processing in image-guided radiation...

journal_title：Physics in medicine and biology

authors： Tanaka R,Sanada S,Sakuta K,Kawashima H

更新日期：2015-05-21 00:00:00

abstract：:Low-strength anastomoses and thermal damage of tissue are major concerns in laser tissue welding techniques where laser energy is used to induce thermal changes in the molecular structure of the tissues being joined, hence allowing them to bond together. Laser tissue soldering, on the other hand, is a bonding techniqu...

journal_title：Physics in medicine and biology

authors： McNally KM,Sorg BS,Welch AJ,Dawes JM,Owen ER

更新日期：1999-04-01 00:00:00

abstract：:It has been reported that the dose effects of metallic guidewires are significant in intravascular brachytherapy (IVBT) using a beta source. The purpose of this work is to investigate the dependence of these dose effects on guidewire position. The EGS4 Monte Carlo codes were used to perform the dose calculations for t...

journal_title：Physics in medicine and biology

authors： Shih R,Hsu WL,Li XA

更新日期：2002-05-21 00:00:00

abstract：:EGSnrc Monte Carlo simulation was used to investigate dose perturbation effects in prostate seed implant brachytherapy using 125I radioactive seeds used in implant brachytherapy. Dose perturbation effects resulting from the seed mutual attenuation in a prostate seed implant consisting of 27 seeds were investigated. Th...

journal_title：Physics in medicine and biology

authors： Mobit P,Badragan I

更新日期：2004-07-21 00:00:00

abstract：:While megavoltage cone-beam computed tomography (CBCT) using an electronic portal imaging device (EPID) provides many advantages over kilovoltage (kV) CBCT, clinical adoption is limited by its high doses. Multi-layer imager (MLI) EPIDs increase DQE(0) while maintaining high resolution. However, even well-designed, hig...

journal_title：Physics in medicine and biology

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

更新日期：2018-01-30 00:00:00

abstract：:An original method for the analysis of oscillations of cutaneous blood flow has been developed, which makes use of laser Doppler flowmetry (LDF) data and is based on the continuous wavelet transform and adaptive wavelet theory. The potential of the method has been demonstrated in experiments with the response of micro...

journal_title：Physics in medicine and biology

authors： Tankanag A,Chemeris N

更新日期：2008-11-07 00:00:00

abstract：:It has been demonstrated that gas-filled microbubble contrast agents, based on their volume changes, can serve as pressure probes in an MR field. It was recently reported that such an MR-based pressure measurement with microbubbles at 1.5 T must make use of microbubbles that have a volumetric magnetic susceptibility d...

journal_title：Physics in medicine and biology

authors： Dharmakumar R,Plewes DB,Wright GA

更新日期：2005-10-21 00:00:00

abstract：:Recent developments in the technique of constant infusion and in emission computed tomography have provided a new method for quantitative regional flow measurements. This paper re-examines critically the theoretical relationship between flow and radioactivity during constant infusion of short-lived isotopes. Sensitivi...

journal_title：Physics in medicine and biology

authors： Huang SC,Phelps ME,Hoffman EJ,Kuhl DE

更新日期：1979-11-01 00:00:00

abstract：:This paper presents a computer simulation of photon interaction with collimator septa, which allows the point spread function of scintillation camera collimators to be calculated. The method simulates photon attenuation along their propagation direction in a determinist way. Using this simulation, the spatial resoluti...

journal_title：Physics in medicine and biology

authors： Gantet P,Esquerré JP,Danet B,Guiraud R

更新日期：1990-05-01 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：:Computer aided detection (CADe) for breast lesion can provide an important reference for radiologists in breast cancer screening. Architectural distortion (AD) is a type of breast lesion that is difficult to detect. A majority of CADe methods focus on detecting the radial pattern, which is a main characteristic of typ...

journal_title：Physics in medicine and biology

authors： Li Y,He Z,Lu Y,Ma X,Guo Y,Xie Z,Xu Z,Chen W,Chen H

更新日期：2020-06-02 00:00:00

abstract：:The measurand relevant for the dosimetry for radiation therapy is the absorbed dose to water, DW. The Physikalisch-Technische Bundesanstalt (PTB) is establishing a secondary standard for DW for high-energy photon and electron radiation based on electron spin resonance (ESR) of the amino acid alanine. For practical app...

journal_title：Physics in medicine and biology

authors： Anton M

更新日期：2008-03-07 00:00:00

abstract：:We report a simulation study on diffuse reflective optical computed tomography, in which continuous-wave sources and detectors are placed on the plane surface of a semi-infinite body. We adopted a simple Tikhonov regularization in the inverse problem and demonstrated the feasibility of three-dimensional reconstruction...

journal_title：Physics in medicine and biology

authors： Endoh R,Suzuki A,Fujii M,Nakayama K

更新日期：2004-05-21 00:00:00

abstract：:Over the last two years we have evaluated paediatric patient doses in projection radiography derived from exposure level (EL) in computed radiography (CR) in a large university hospital. Entrance surface air kerma (ESAK) for 3501 paediatric examinations was calculated from the EL, which is a dose index parameter relat...

journal_title：Physics in medicine and biology

authors： Vano E,Martinez D,Fernandez JM,Ordiales JM,Prieto C,Floriano A,Ten JI

更新日期：2008-06-21 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：:Four-dimensional volumetric modulated arc therapy (4D VMAT) is a treatment strategy for lung cancers that aims to exploit relative target and tissue motion to improve organ at risk (OAR) sparing. The algorithm incorporates the entire patient respiratory cycle using 4D CT data into the optimization process. Resulting t...

journal_title：Physics in medicine and biology

authors： Chin E,Loewen SK,Nichol A,Otto K

更新日期：2013-02-21 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：:This paper reports a theoretical study on the distribution of blood flow in the human cardiovascular system when one or more blood vessels are affected by stenosis. The analysis employs a mathematical model of the entire system based on the finite element method. The arterial-venous network is represented by a large n...

journal_title：Physics in medicine and biology

authors： Sud VK,Srinivasan RS,Charles JB,Bungo MW

更新日期：1993-03-01 00:00:00

abstract：:The purpose of this study was the characterization of local magnetic susceptibility deviations by spectral analysis of their induced magnetic field inhomogeneities. Magnetic resonance spectra and related signal decay curves of local susceptibility deviations were simulated for different volume fractions and compositio...

journal_title：Physics in medicine and biology

authors： Seppenwoolde JH,van Zijtveld M,Bakker CJ

更新日期：2005-01-21 00:00:00

abstract：:The effects of radiation damage, tumour repopulation and cell sublethal damage repair and the possibility of extracting information about the model parameters describing them are investigated in this work. Previously published data on two different cultured cell lines were analysed with the help of a tumour control pr...

journal_title：Physics in medicine and biology

authors： Stavrev P,Weldon M,Warkentin B,Stavreva N,Fallone BG

更新日期：2005-07-07 00:00:00

abstract：:This study investigates the dosimetric impact of using population-based Hounsfield units (HUs) and ICRU-based HUs as a function of the number of tissue segments for bulk density assignment toward MRI-based treatment planning in the abdomen. To avoid potential geometric differences between CT and MR images, CT images r...

journal_title：Physics in medicine and biology

authors： Hsu SH,Zawisza I,O'Grady K,Peng Q,Tomé WA

更新日期：2018-07-24 00:00:00

abstract：:Intraoperative x-ray radiography/fluoroscopy is commonly used to assess the placement of surgical devices in the operating room (e.g. spine pedicle screws), but qualitative interpretation can fail to reliably detect suboptimal delivery and/or breach of adjacent critical structures. We present a 3D-2D image registratio...

journal_title：Physics in medicine and biology

authors： Uneri A,De Silva T,Goerres J,Jacobson MW,Ketcha MD,Reaungamornrat S,Kleinszig G,Vogt S,Khanna AJ,Osgood GM,Wolinsky JP,Siewerdsen JH

更新日期：2017-04-21 00:00:00

abstract：:Ultraviolet (UV) treatment dose is determined by the length of time that a patient spends in a phototherapy cabin. The output from UV fluorescent lamps declines with use and a method is needed to compensate for the change in irradiance and to identify and replace any lamps that fail. The decline in lamp output with ag...

journal_title：Physics in medicine and biology

authors： Amatiello H,Martin CJ

更新日期：2006-01-21 00:00:00

abstract：:A post-processing noise suppression technique for biomedical MRI images is presented. The described procedure recovers both sharp edges and smooth surfaces from a given noisy MRI image; it does not blur the edges and does not introduce spikes or other artefacts. The fine details of the image are also preserved. The pr...

journal_title：Physics in medicine and biology

authors： Placidi G,Alecci M,Sotgiu A

更新日期：2003-07-07 00:00:00

abstract：:The degradation of low energy electrons in a methane based, tissue equivalent gas was studied experimentally by ionization chamber experiments and theoretically by Monte Carlo electron transport simulation in the energy range between 25 eV and 5 keV. From measured ionization yields and calculated ionization and energy...

journal_title：Physics in medicine and biology

authors： Waibel E,Grosswendt B

更新日期：1992-05-01 00:00:00

abstract：:In radiotherapy with photon beams, the use of dynamic wedges, which are obtained by the movement of one of the jaws, offers an increasing flexibility relative to the traditional use of metal wedges. But it is a disadvantage for the measurement of absorbed dose distributions, because the absorbed dose at each measureme...

journal_title：Physics in medicine and biology

authors： Storchi P,Woudstra E,Verlinde P,Johansson KA,Samuelsson A

更新日期：1998-06-01 00:00:00