Microdosimetric investigations on collimated fast neutron beams for radiation therapy: II. The problem of radiation quality and RBE.

abstract：:This paper presents finite-difference time-domain (FDTD) calculations of the whole-body averaged SAR in an anatomically realistic voxel model of the human body. This model, NORMAN, consists of approximately 9 million voxels, of 2 mm dimension in the adult phantom, segmented into 37 tissue types. SAR values are present...

journal_title：Physics in medicine and biology

authors： Dimbylow PJ

更新日期：1997-03-01 00:00:00

abstract：:We review the application of fluorescence spectroscopy and elastic-scattering spectroscopy, over the ultraviolet-to-visible wavelength range, to minimally invasive medical diagnostics. The promises and hopes, as well as the difficulties, of these developing techniques are discussed. ...

journal_title：Physics in medicine and biology

authors： Bigio IJ,Mourant JR

更新日期：1997-05-01 00:00:00

abstract：:This work presents an improvement of the VIPARnd ('nd' stands for 'normoxic, double', or VIP) polymer gel dosimeter. The gel composition was altered by increasing the concentration of the monomeric components, N-vinylpyrrolidone (NVP) and N,N'-methylenebisacrylamide (MBA), in co-solvent solutions. The optimal composit...

journal_title：Physics in medicine and biology

authors： Kozicki M,Jaszczak M,Maras P,Dudek M,Cłapa M

更新日期：2017-02-07 00:00:00

abstract：:Calculating the dynamic properties of magnetization of single-domain particles is of great importance for the tomographic imaging modality known as magnetic particle imaging (MPI). Although the assumption of instantaneous thermodynamic equilibrium (Langevin function) after application of time-dependent magnetic fields...

journal_title：Physics in medicine and biology

authors： Weizenecker J

更新日期：2018-01-22 00:00:00

abstract：:At present, there exists few openly available methods for evaluation of simultaneous segmentation and registration algorithms. These methods allow for a combination of both techniques to track the tumor in complex settings such as adaptive radiotherapy. We have produced a quality assurance platform for evaluating this...

journal_title：Physics in medicine and biology

authors： Markel D,Levesque I,Larkin J,Léger P,El Naqa I

更新日期：2016-10-07 00:00:00

abstract：:The aim of this study is to determine the impact of longitudinal micro-CT imaging on the growth of B16F1 tumours in C57BL/6 mice. Sixty mice received 2 × 10(5) B16F1 cells subcutaneously in the hind flank and were divided into control (no scan), 'low-dose' (80 kVp, 70 mA, 8 s, 0.07 Gy), 'medium-dose' (80 kVp, 50 mA, 3...

journal_title：Physics in medicine and biology

authors： Foster WK,Ford NL

更新日期：2011-01-21 00:00:00

abstract：:The trend towards conformal, intensity modulated radiotherapy treatments has established the need for a true integrating dosimeter. In traditional radiotherapy, radiographic film dosimetry is commonly used. The accuracy and reproducibility of film optical density as an indicator of dose is influenced by several variab...

journal_title：Physics in medicine and biology

authors： Suchowerska N,Hoban P,Butson M,Davison A,Metcalfe P

更新日期：2001-05-01 00:00:00

abstract：:A method of computing optimized intensity-modulated beam profiles has been further developed and used to generate highly conformal radiotherapy dose distributions. The features of these distributions are shown to be strongly dependent on the tuning built into the algorithm. The optimization aims to achieve a specified...

journal_title：Physics in medicine and biology

authors： Webb S

更新日期：1994-12-01 00:00:00

abstract：:For angiography using synchrotron radiation we measured the absorbed dose distribution in inhomogeneous phantoms with thin LiF:Mg, Cu, P, LiF:Mg, Ti thermoluminescent dosimeters (TLDs) in tissue and lung substitutes, and with Mg2SiO4:Tb TLDs in bone substitute for 33.32 keV monoenergetic photons from synchrotron radia...

journal_title：Physics in medicine and biology

authors： Nariyama N,Namito Y,Ban S,Hirayama H

更新日期：2001-03-01 00:00:00

abstract：:Dual energy computed tomography (DECT) is currently a subject of extensive investigation. DECT is currently implemented using either a dual source scanner with high and low kVp data acquired from separate sources or a single source scanner with both high and low kVp data acquired in an alternating manner. Both methods...

journal_title：Physics in medicine and biology

authors： Szczykutowicz TP,Chen GH

更新日期：2010-11-07 00:00:00

abstract：:Intensity modulated radiation therapy (IMRT) inverse planning using total-variation (TV) regularization has been proposed to reduce the complexity of fluence maps and facilitate dose delivery. Conventionally, the optimization problem with L-1 norm is solved with quadratic programming (QP), which is time consuming and ...

journal_title：Physics in medicine and biology

authors： Kim H,Suh TS,Lee R,Xing L,Li R

更新日期：2012-07-07 00:00:00

abstract：:Although the calculation of the surface average of the low-frequency current density distribution over a cross-section of 1 cm2 is required by ICNIRP guidelines, no reference averaging algorithm is indicated, neither in the ICNIRP guidelines nor in the Directive 2004/40/EC that is based on them. The lack of a general ...

journal_title：Physics in medicine and biology

authors： Zoppetti N,Andreuccetti D

更新日期：2009-08-07 00:00:00

abstract：:The measured attenuation correction technique is widely used in cardiac positron tomographic studies. However, the success of this technique is limited because of insufficient counting statistics achievable in practical transmission scan times, and of the scattered radiation in transmission measurement which leads to ...

journal_title：Physics in medicine and biology

authors： Yu SK,Nahmias C

更新日期：1996-10-01 00:00:00

abstract：:In carbon ion therapy treatment planning, the relative biological effectiveness (RBE) is accounted for by optimization of the RBE-weighted dose (biological dose). The RBE calculation methods currently applied clinically in carbon ion therapy are derived from the microdosimetric kinetic model (MKM) in Japan and the loc...

journal_title：Physics in medicine and biology

authors： Dahle TJ,Magro G,Ytre-Hauge KS,Stokkevåg CH,Choi K,Mairani A

更新日期：2018-11-12 00:00:00

abstract：:This work investigated the differences between multileaf collimator (MLC) positioning accuracy determined using either log files or electronic portal imaging devices (EPID) and then assessed the possibility of reducing patient specific quality control (QC) via phantom-less methodologies. In-house software was develope...

journal_title：Physics in medicine and biology

authors： Agnew A,Agnew CE,Grattan MW,Hounsell AR,McGarry CK

更新日期：2014-05-07 00:00:00

abstract：:This work compared the impact of x-ray tube performance and automatic dose rate control (ADRC) parameter selection on system imaging efficiency of two Siemens angiography systems: a Siemens Megalix x-ray tube installed on an Artis Zee system (denoted 'MEGALIX') and a newer generation Gigalix x-ray tube installed on an...

journal_title：Physics in medicine and biology

authors： Dehairs M,Bosmans H,Marshall NW

更新日期：2020-11-24 00:00:00

abstract：:In elastography we have previously developed a tracking and correction method that estimates the axial and lateral strain components along and perpendicular to the compressor/scanning axis following an externally applied compression. However, the resulting motion is a three-dimensional problem. Therefore, in order to ...

journal_title：Physics in medicine and biology

authors： Konofagou EE,Ophir J

更新日期：2000-06-01 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：:Generally, the inverse planning of radiation therapy consists mainly of the fluence optimization. The beam angle optimization (BAO) in intensity-modulated radiation therapy (IMRT) consists of selecting appropriate radiation incidence directions and may influence the quality of the IMRT plans, both to enhance better or...

journal_title：Physics in medicine and biology

authors： Rocha H,Dias JM,Ferreira BC,Lopes MC

更新日期：2013-05-07 00:00:00

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：:Temporal regularization plays a critical role in cardiac gated dynamic SPECT reconstruction, of which the goal is to obtain an image sequence from a single acquisition which simultaneously shows both cardiac motion and tracer distribution change over the course of imaging (termed 5D). In our recent work, we explored t...

journal_title：Physics in medicine and biology

authors： Niu X,Yang Y,King MA

更新日期：2012-09-07 00:00:00

abstract：:Absorbed dose values were determined under the reference conditions in a phantom irradiated by high-energy photon beams with quality varying between 60Co gamma rays and 25 MV X-rays, using four commonly employed types of ionisation chamber. The ionisation chamber readings were converted to absorbed dose values applyin...

journal_title：Physics in medicine and biology

authors： Mijnheer BJ,Wittkämper FW

更新日期：1986-04-01 00:00:00

abstract：:The purpose of this study is to calculate Pareto surfaces in multi-criteria radiation treatment planning and to analyse the dependency of the Pareto surfaces on the objective functions used for the volumes of interest. We develop a linear approach that allows us to calculate truly Pareto optimal treatment plans, and w...

journal_title：Physics in medicine and biology

authors： Craft D,Halabi T,Bortfeld T

更新日期：2005-12-21 00:00:00

abstract：:A leaf-setting algorithm is developed for generating arbitrary beam intensity profiles in discrete levels using dynamic multileaf collimators (DMLCs). The algorithm starts with the algebraic expression for the area under the beam profile. It is shown that the coefficients in this expression can be transformed into the...

journal_title：Physics in medicine and biology

authors： Ma L,Boyer AL,Xing L,Ma CM

更新日期：1998-06-01 00:00:00

abstract：:We propose a regularized least-squares method for reconstructing 2D velocity vector fields within the left ventricular cavity from single-view color Doppler echocardiographic images. Vector flow mapping is formulated as a quadratic optimization problem based on an [Formula: see text]-norm minimization of a cost functi...

journal_title：Physics in medicine and biology

authors： Assi KC,Gay E,Chnafa C,Mendez S,Nicoud F,Abascal JFPJ,Lantelme P,Tournoux F,Garcia D

更新日期：2017-08-11 00:00:00

abstract：:The potential of the variable-aperture collimator (VAC) in intensity-modulated radiation therapy (IMRT) has been evaluated by comparing its performance with that of the multi-leaf collimator (MLC). This comparison used a decomposition algorithm to find the series of collimator segments that would treat a given intensi...

journal_title：Physics in medicine and biology

authors： Anderson JW,Symonds-Tayler R,Hartmann G,Echner G,Lang C,Schlegel W,Webb S

更新日期：2006-04-07 00:00:00

abstract：:Dynamic 18F-FDG PET with tracer kinetic modeling has the potential to noninvasively evaluate human liver inflammation using the FDG blood-to-tissue transport rate K 1. Accurate kinetic modeling of dynamic liver PET data and K 1 quantification requires the knowledge of dual-blood input function from the hepatic artery ...

journal_title：Physics in medicine and biology

authors： Zuo Y,Sarkar S,Corwin MT,Olson K,Badawi RD,Wang G

更新日期：2019-09-05 00:00:00

abstract：:The S-value is a standard measure in cellular dosimetry. S-values are calculated by applying analytical methods or by Monte Carlo simulation. In Monte Carlo simulation, particles are either tracked individually event-by-event or close events are condensed and processed collectively in different steps. Both of these me...

journal_title：Physics in medicine and biology

authors： Tajik-Mansoury MA,Rajabi H,Mozdarani H

更新日期：2017-03-07 00:00:00

abstract：:The in vivo electric conductivity (σ) values of tissue are essential for accurate electromagnetic simulations and specific absorption rate (SAR) assessment for applications such as thermal dose computations in hyperthermia. Currently used σ-values are mostly based on ex vivo measurements. In this study the conductivit...

journal_title：Physics in medicine and biology

authors： Balidemaj E,de Boer P,van Lier AL,Remis RF,Stalpers LJ,Westerveld GH,Nederveen AJ,van den Berg CA,Crezee J

更新日期：2016-02-21 00:00:00

abstract：:New definitions of the absorbed dose conversion factors Clambda and CE are proposed. The absorbed dose in water is given by the product of absorbed dose conversion factor, exposure calibration factor, ionisation chamber reading, cap displacement correction factor and perturbation correction factor. At exposure calibra...

journal_title：Physics in medicine and biology

authors： Shiragai A

更新日期：1978-03-01 00:00:00