Evaluation of nonuniform field exposures with coupling factors.

abstract：:Diffusion tensor - magnetic resonance electrical impedance tomography (DT-MREIT) is an imaging modality to obtain low-frequency anisotropic conductivity distribution employing diffusion tensor imaging (DTI) and magnetic resonance electrical impedance tomography (MREIT) techniques. DT-MREIT is based on the linear relat...

journal_title：Physics in medicine and biology

authors： Sadighi M,Sisman M,Acikgoz BC,Eroglu HH,Eyuboglu BM

更新日期：2021-01-20 00:00:00

abstract：:Factors influencing the precision of measuring changes in the calcium content of sections of bone, including vertebrae, using reactor neutrons for partial body in vivo activation analysis have been examined and quantified. These factors include (a) the choice of incidient neutron spectrum, (b) the uniformity of activa...

journal_title：Physics in medicine and biology

authors： Boddy K,Glaros D,Robertson I

更新日期：1975-01-01 00:00:00

abstract：:The interactions between energetic ions and biological and/or organic target materials have recently attracted theoretical and experimental attention, due to their implications for detector and device technologies, and for therapeutic applications. Most of the attention has focused on detection of the primary ionizati...

journal_title：Physics in medicine and biology

authors： Falzone N,Myhra S,Chakalova R,Hill MA,Thomson J,Vallis KA

更新日期：2013-11-07 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：:In dynamic renal scintigraphy, the main interest is the radiopharmaceutical redistribution as a function of time. Quality control (QC) of renal procedures often relies on phantom experiments to compare image-based results with the measurement setup. A phantom with a realistic anatomy and time-varying activity distribu...

journal_title：Physics in medicine and biology

authors： Brolin G,Gleisner KS,Ljungberg M

更新日期：2013-05-21 00:00:00

abstract：:Two different classifiers, an artificial neural network (ANN) and a hybrid system (one step rule-based method followed by an artificial neural network) have been investigated to merge computer-extracted features in the task of differentiating between malignant and benign masses. A database consisting of 65 cases (38 m...

journal_title：Physics in medicine and biology

authors： Huo Z,Giger ML,Metz CE

更新日期：1999-10-01 00:00:00

abstract：:Stroke lesion volume is a key radiologic measurement in assessing prognosis of acute ischemic stroke (AIS) patients. The aim of this paper is to develop an automated segmentation method for accurately segmenting follow-up ischemic and hemorrhagic lesion from multislice non-contrast CT (NCCT) volumes of AIS patients. T...

journal_title：Physics in medicine and biology

authors： Kuang H,Menon BK,Qiu W

更新日期：2020-11-05 00:00:00

abstract：:To increase the scanning speed of cone-beam CT, a scanning configuration with three pairs of x-ray sources and panel detectors was proposed. In this paper, we apply the M-line-based backprojected filtration algorithm to this scanning configuration and propose a fast implementation for this algorithm. Compared with exi...

journal_title：Physics in medicine and biology

authors： Zhao Y,Zhu Y,Zhang P

更新日期：2010-12-07 00:00:00

abstract：:This work aims to investigate the dosimetric impact of dental implants on volumetric modulated arc therapy (VMAT) for head-and-neck patients and to evaluate the effectiveness of using the material's electron-density ratio for the correction. An in-house Monte Carlo (MC) code was utilized for the dose calculation to ac...

journal_title：Physics in medicine and biology

authors： Lin MH,Li J,Price RA Jr,Wang L,Lee CC,Ma CM

更新日期：2013-02-21 00:00:00

abstract：:Despite over ten years of in vitro investigations of ultrasound contrast agents, the level of understanding of their behaviour in ultrasound fields is limited. Several problems associated with these investigations, particular to the nature of contrast agents, are discussed. Using a commercial scanner the RF normalized...

journal_title：Physics in medicine and biology

authors： Sboros V,Ramnarine KV,Moran CM,Pye SD,McDicken WN

更新日期：2002-12-07 00:00:00

abstract：:Proton, as well as other ion, beams applied by electro-magnetic deflection in pencil-beam scanning (PBS) are minimally perturbed and thus can be quantified a priori by their fundamental interactions in a medium. This a priori quantification permits an optimal reduction of characterizing measurements on a particular PB...

journal_title：Physics in medicine and biology

authors： Clasie B,Depauw N,Fransen M,Gomà C,Panahandeh HR,Seco J,Flanz JB,Kooy HM

更新日期：2012-03-07 00:00:00

abstract：:'Patlak analysis' is a common approach used in Fdopa PET studies to calculate the uptake constant (Ki) of the tracer. It is assumed in the Patlak analysis that the reversible compartment of tissue radioactivity used is in effective equilibrium with the tracer in plasma. Therefore, using the data prior to equilibrium i...

journal_title：Physics in medicine and biology

authors： Yu DC,Huang SC,Barrio JR,Phelps ME

更新日期：1995-07-01 00:00:00

abstract：:Dose factors for locations within a tissue-filled cylindrical cavity bounded by an infinite medium of bone labelled with an alpha-emitter are calculated by means of a Monte Carlo procedure. The calculational approach is general and allows us to determine dose factors for specific distances or target volumes defined by...

journal_title：Physics in medicine and biology

authors： Polig E

更新日期：1989-03-01 00:00:00

abstract：:A phantom study was performed in full-field digital mammography to investigate the opportunity and the magnitude of a possible dose reduction that would leave the image quality above the accepted thresholds associated with some classical phantoms. This preliminary work is intended to lay the groundwork for a future cl...

journal_title：Physics in medicine and biology

authors： Gennaro G,Katz L,Souchay H,Alberelli C,di Maggio C

更新日期：2005-04-21 00:00:00

abstract：:We report on a set of cell survival experiments performed in complex field combinations of therapeutic 12C ion beams. CHO cells were exposed to the superposition of two or three fields of 12C ions arranged in a similar way to real patient treatments. Two-dimensional survival distributions were measured and compared wi...

journal_title：Physics in medicine and biology

authors： Krämer M,Wang JF,Weyrather W

更新日期：2003-07-21 00:00:00

abstract：:The aim of this study is to investigate the use of mathematical morphology for the determination of left ventricular contours in scintigraphic images using multigated radionuclide angiography. We have developed a completely automatic method that first restores the image with a Wiener filter, then finds the region wher...

journal_title：Physics in medicine and biology

authors： Pladellorens J,Serrat J,Castell A,Yzuel MJ

更新日期：1993-12-01 00:00:00

abstract：:Mitral and aortic valve replacement is a procedure which is common in cardiac surgery. Some of these replacement valves are mechanical and contain moving metal parts. Should the patient in whom such a valve has been implanted be involved in magnetic resonance imaging, there is a possible dangerous interaction between ...

journal_title：Physics in medicine and biology

authors： Robertson NM,Diaz-Gomez M,Condon B

更新日期：2000-12-01 00:00:00

abstract：:Statistically based iterative image reconstruction methods have been developed for emission tomography. One important component in iterative image reconstruction is the system matrix, which defines the mapping from the image space to the data space. Several groups have demonstrated that an accurate system matrix can i...

journal_title：Physics in medicine and biology

authors： Qi J,Huesman RH

更新日期：2005-07-21 00:00:00

abstract：:The quality of thorax and pelvis transmission scans and therefore of attenuation correction in PET depends on patient thickness and transmission rod source strength. The purpose of the present study was to assess the feasibility of using count-based transmission scans, thereby guaranteeing more consistent image qualit...

journal_title：Physics in medicine and biology

authors： Boellaard R,van Lingen A,van Balen SC,Lammertsma AA

更新日期：2004-02-21 00:00:00

abstract：:In this paper the propagation of a UWB pulse into a layered model of the human body is studied to characterize absorption and reflection of the UWB signal due to the different body tissues. Several time behaviours for the incident UWB pulse are considered and compared with reference to the feasibility of breath and he...

journal_title：Physics in medicine and biology

authors： Cavagnaro M,Pittella E,Pisa S

更新日期：2013-12-21 00:00:00

abstract：:In BANG gel dosimetry, the spin-spin relaxation rate, R2 = I/T2, is related to the radiation dose that has been delivered to the gel phantom. R2 is calculated by fitting the pixel intensities of a set of differently T2-weighted base images. In gel dosimetry for radiotherapy, an accuracy of 5% in dose and 3 mm spatiall...

journal_title：Physics in medicine and biology

authors： De Deene Y,De Wagter C,De Neve W,Achten E

更新日期：2000-07-01 00:00:00

abstract：:A medical research protocol on clinical intravenous coronary angiography has been completed at the European Synchrotron Radiation Facility (ESRF) biomedical beamline. The aim was to investigate the accuracy of intravenous coronary angiography based on the K-edge digital subtraction technique for the detection of in-st...

journal_title：Physics in medicine and biology

authors： Sarnelli A,Nemoz C,Elleaume H,Estève F,Bertrand B,Bravin A

更新日期：2005-02-21 00:00:00

abstract：:This study investigated the integration of the Calypso real-time tracking system, based on implanted ferromagnetic transponders and a detector array, into the current process for image-guided radiation treatment (IGRT) of prostate cancer at our institution. The current IGRT process includes magnetic resonance imaging ...

journal_title：Physics in medicine and biology

authors： Zhu X,Bourland JD,Yuan Y,Zhuang T,O'Daniel J,Thongphiew D,Wu QJ,Das SK,Yoo S,Yin FF

更新日期：2009-09-07 00:00:00

abstract：:The beam orientation optimization (BOO) problem in intensity modulated radiation therapy (IMRT) treatment planning is a nonlinear problem, and existing methods to obtain solutions to the BOO problem are time consuming due to the complex nature of the objective function and size of the solution space. These issues beco...

journal_title：Physics in medicine and biology

authors： Lee CH,Aleman DM,Sharpe MB

更新日期：2011-09-07 00:00:00

abstract：:Radiotherapy treatment planning is associated with uncertainties. Examples are uncertainties in the tumour location due to organ movement or the inter/intra observer variability in target definition. Different approaches to incorporate uncertainties into IMRT optimization have been proposed. In this note, we point out...

journal_title：Physics in medicine and biology

authors： Unkelbach J,Oelfke U

更新日期：2006-12-07 00:00:00

abstract：:Nuclear emulsions of the Ilford K series, exposed to X-rays from 15 to 150 kVp and systematically underdeveloped, exhibit supralinear blackness--exposure curves ranging from 1- to 4-hit in character, and whose shape is the same at all excitation voltages. Processing can be so adjusted that the curve shape is well repr...

journal_title：Physics in medicine and biology

authors： Katz R,Pennington EC

更新日期：1978-11-01 00:00:00

abstract：:The quantification of tumor motion in sites affected by respiratory motion is of primary importance to improve treatment accuracy. To account for motion, different studies analyzed the translational component only, without focusing on the rotational component, which was quantified in a few studies on the prostate with...

journal_title：Physics in medicine and biology

authors： Paganelli C,Lee D,Greer PB,Baroni G,Riboldi M,Keall P

更新日期：2015-09-21 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：:Respiratory induced resonance offset (RIRO) is a periodic disturbance of a magnetic field due to breathing. Such disturbance handicaps the accuracy of the proton resonance frequency shift (PRFS) method of MRI temperature mapping in anatomies situated nearby the lungs and chest wall. In this work, we propose a method c...

journal_title：Physics in medicine and biology

authors： Shmatukha AV,Bakker CJ

更新日期：2006-09-21 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