Monte Carlo calculation of VMAT and helical tomotherapy dose distributions for lung stereotactic treatments with intra-fraction motion.

abstract：:Pinhole SPECT is rapidly gaining popularity for imaging laboratory animals using gamma-emitting molecules. Penetration and scattering of gamma radiation in the pinhole edge material can account for a significant fraction of the total number of photons detected, particularly if the pinholes have small diameters. This s...

journal_title：Physics in medicine and biology

authors： van der Have F,Beekman FJ

更新日期：2004-04-21 00:00:00

abstract：:We developed and validated a Monte-Carlo-based application (RAYDOSE) to generate patient-specific 3D dose maps on the basis of pre-treatment imaging studies. A CT DICOM image is used to model patient geometry, while repeated PET scans are employed to assess radionuclide kinetics and distribution at the voxel level. In...

journal_title：Physics in medicine and biology

authors： Marcatili S,Pettinato C,Daniels S,Lewis G,Edwards P,Fanti S,Spezi E

更新日期：2013-04-21 00:00:00

abstract：:In order to measure in vivo resistivity of tissues in the thorax, the possibility of combining anatomical data extracted from high-resolution images with multiple-electrode impedance measurements, a priori knowledge of the range of tissue resistivities, and a priori data on the instrumentation noise is assessed in thi...

journal_title：Physics in medicine and biology

authors： Eyüboğlu BM,Pilkington TC,Wolf PD

更新日期：1994-01-01 00:00:00

abstract：:The application of thermal modelling for hyperthermia and thermal ablation is severely hampered by lack of information about perfusion and vasculature. However, recently, with the advent of sophisticated angiography and dynamic contrast enhanced (DCE) imaging techniques, it has become possible to image small vessels a...

journal_title：Physics in medicine and biology

authors： Van den Berg CA,Van de Kamer JB,De Leeuw AA,Jeukens CR,Raaymakers BW,van Vulpen M,Lagendijk JJ

更新日期：2006-02-21 00:00:00

abstract：:Measurements have been made using an air sampler to measure airborne radioactivity produced during the routine handling of large activities of technetium-99m, iodine-125 and iodine-131. The results indicate that 99Tcm can be safely handled in environments without direct exhaust of the ventilated air but that 125I and ...

journal_title：Physics in medicine and biology

authors： Eadie AS,Horton PW,Hilditch TE

更新日期：1980-11-01 00:00:00

abstract：:The most advanced delivery technique for proton radiotherapy is active spot scanning. So far, predominantly static targets have been treated with active spot scanning, since mobile targets in combination with dynamic treatment delivery can lead to interplay effects, causing inhomogeneous dose distributions. One way to...

journal_title：Physics in medicine and biology

authors： Knopf AC,Hong TS,Lomax A

更新日期：2011-11-21 00:00:00

abstract：:Recent research has suggested that endothelialization of vascular stents is crucial to reducing the risk of late stent thrombosis. With a resolution of approximately 10 microm, optical coherence tomography (OCT) may be an appropriate imaging modality for visualizing the vascular response to a stent and measuring the p...

journal_title：Physics in medicine and biology

authors： Bonnema GT,Cardinal KO,Williams SK,Barton JK

更新日期：2008-06-21 00:00:00

abstract：:Technical advances towards high resolution PET imaging try to overcome the inherent physical limitations to spatial resolution. Positrons travel in tissue until they annihilate into the two gamma photons detected. This range is the main detector-independent contribution to PET imaging blurring. To a large extent, it c...

journal_title：Physics in medicine and biology

authors： Cal-González J,Herraiz JL,España S,Corzo PM,Vaquero JJ,Desco M,Udias JM

更新日期：2013-08-07 00:00:00

abstract：:This paper analyzes the radio frequencies (RF) exposure in the head tissues of children using a cellular handset or RF sources (a dipole and a generic handset) at 900, 1800, 2100 and 2400 MHz. Based on magnetic resonance imaging, child head models have been developed. The maximum specific absorption rate (SAR) over 10...

journal_title：Physics in medicine and biology

authors： Wiart J,Hadjem A,Wong MF,Bloch I

更新日期：2008-07-07 00:00:00

abstract：:Several types of intravascular ultrasound (IVUS) catheters are connected to a motor at their proximal end, in order to let the catheter rotate around its length axis. However, the rotation of the distal axis tip does not follow exactly the rotation of the motor, since the catheter axis is not completely torsion-free a...

journal_title：Physics in medicine and biology

authors： Konings MK,van Leeuwen TG,Mali WP,Viergever MA

更新日期：1998-05-01 00:00:00

abstract：:This study investigated the relationship between the specific absorption rate and temperature elevation in an anatomically-based model named NORMAN for exposure to radio-frequency far fields in the ICNIRP guidelines (1998 Health Phys. 74 494-522). The finite-difference time-domain method is used for analyzing the elec...

journal_title：Physics in medicine and biology

authors： Hirata A,Asano T,Fujiwara O

更新日期：2007-08-21 00:00:00

abstract：:The University of Washington (UW) Clinical Neutron Therapy System (CNTS) has been used to treat over 3300 patients. Treatment planning for these patients is currently performed using an MV x-ray model in Pinnacle® adapted to fit measurements of fast neutron output factors, wedge factors, depth-dose and lateral profile...

journal_title：Physics in medicine and biology

authors： Moffitt GB,Wootton LS,Hårdemark B,Sandison GA,Laramore GE,Parvathaneni U,Stewart RD

更新日期：2020-08-31 00:00:00

abstract：:It has been reported that acoustic waves are generated when a high-energy pulsed proton beam is deposited in a small volume within tissue. One possible application of proton-induced acoustics is to get real-time feedback for intra-treatment adjustments by monitoring such acoustic waves. A high spatial resolution in ul...

journal_title：Physics in medicine and biology

authors： Kipergil EA,Erkol H,Kaya S,Gulsen G,Unlu MB

更新日期：2017-06-21 00:00:00

abstract：:Non-invasive evaluation of the Achilles tendon elastic properties may enhance diagnosis of tendon injury and the assessment of recovery treatments. Shear wave elastography has shown to be a powerful tool to estimate tissue mechanical properties. However, its applicability to quantitatively evaluate tendon stiffness is...

journal_title：Physics in medicine and biology

authors： Brum J,Bernal M,Gennisson JL,Tanter M

更新日期：2014-02-07 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：:A Monte Carlo model of a novel electronic portal imaging device (EPID) has been developed using Geant4 and its performance for imaging and dosimetry applications in radiotherapy has been characterised. The EPID geometry is based on a physical prototype under ongoing investigation and comprises an array of plastic scin...

journal_title：Physics in medicine and biology

authors： Blake SJ,McNamara AL,Vial P,Holloway L,Kuncic Z

更新日期：2014-11-21 00:00:00

abstract：:This study presents the computational dosimetry of contact currents for grounded and ungrounded human models. The uncertainty of the quasi-static (QS) approximation of the in situ electric field induced in a grounded/ungrounded human body due to the contact current is first estimated. Different scenarios of cylindrica...

journal_title：Physics in medicine and biology

authors： Chan KH,Hattori J,Laakso I,Hirata A,Taki M

更新日期：2013-08-07 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：:The aim of magnetic resonance electrical impedance tomography (MREIT) is to visualize the electrical properties, conductivity or current density of an object by injection of current. Recently, the prolonged data acquisition time when using the injected current nonlinear encoding (ICNE) method has been advantageous for...

journal_title：Physics in medicine and biology

authors： Nam HS,Kwon OI

更新日期：2010-05-07 00:00:00

abstract：:Skin toxicity has been reported for IMRT of head and neck cancer. The purpose of this study was to investigate the dose in the build-up region delivered by a 6 MV treatment plan for which important skin toxicity was observed. We also investigated if the different designs of the treatment head of an Elekta and a Varian...

journal_title：Physics in medicine and biology

authors： Paelinck L,De Wagter C,Van Esch A,Duthoy W,Depuydt T,De Neve W

更新日期：2005-02-07 00:00:00

abstract：:Analytic solutions to the time-dependent multiregion bioheat equation are evaluated numerically for cartesian and spherical models. Principle and alternate branch contributions to the solutions are examined. The calculations include a parametric investigation and analyses of temperature behaviour in idealised upper th...

journal_title：Physics in medicine and biology

authors： Durkee JW Jr,Antich PP,Lee CE

更新日期：1990-07-01 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

abstract：:In this paper we present a generalized Deep Learning-based approach for solving ill-posed large-scale inverse problems occuring in medical image reconstruction. Recently, Deep Learning methods using iterative neural networks (NNs) and cascaded NNs have been reported to achieve state-of-the-art results with respect to ...

journal_title：Physics in medicine and biology

authors： Kofler A,Haltmeier M,Schaeffter T,Kachelrieß M,Dewey M,Wald C,Kolbitsch C

更新日期：2020-07-06 00:00:00

abstract：:Dosimetry of proton beams is generally evaluated in liquid water, or alternatively in solid phantoms via water equivalent ratios (WER). WER is defined as the ratio of proton range in liquid water to that in a phantom of certain material. Presently, WER is not available in the literature neither for a wide range of ene...

journal_title：Physics in medicine and biology

authors： Safigholi H,Song WY

更新日期：2018-07-27 00:00:00

abstract：:In this study, we evaluate the feasibility of designing a beveled fiber-optic probe coupled with a ball lens for improving depth-resolved fluorescence measurements of epithelial tissue using Monte Carlo (MC) simulations. The results show that by using the probe configuration with a beveled tip collection fiber and a f...

journal_title：Physics in medicine and biology

authors： Jaillon F,Zheng W,Huang Z

更新日期：2008-02-21 00:00:00

abstract：:Kinetic parameters are commonly estimated from dynamically acquired nuclear medicine data by first reconstructing a dynamic sequence of images and subsequently fitting the parameters to time-activity curves generated from regions of interest overlaid upon the image sequence. Biased estimates can result from images rec...

journal_title：Physics in medicine and biology

authors： Huesman RH,Reutter BW,Zeng GL,Gullberg GT

更新日期：1998-04-01 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：:In multiple plan adaptive radiotherapy (ART) strategies of bladder cancer, a library of plans corresponding to different bladder volumes is created based on images acquired in early treatment sessions. Subsequently, the plan for the smallest PTV safely covering the bladder on cone-beam CT (CBCT) is selected as the pla...

journal_title：Physics in medicine and biology

authors： Chai X,van Herk M,Betgen A,Hulshof M,Bel A

更新日期：2012-06-21 00:00:00

abstract：:Shear wave elastography (SWE) is a potential tool to non-invasively assess cardiac muscle stiffness. This study focused on the effect of the orthotropic material properties and mechanical loading on the performance of cardiac SWE, as it is known that these factors contribute to complex 3D anisotropic shear wave propag...

journal_title：Physics in medicine and biology

authors： Caenen A,Pernot M,Peirlinck M,Mertens L,Swillens A,Segers P

更新日期：2018-03-23 00:00:00

abstract：:Abdominal organ motion may lead to considerable uncertainties in pencil-beam scanning (PBS) proton therapy of pancreatic cancer. Beam gating, where irradiation only occurs in certain breathing phases in which the gating conditions are fulfilled, may be an option to reduce the interplay effect between tumor motion and ...

journal_title：Physics in medicine and biology

authors： Dolde K,Naumann P,Dávid C,Kachelriess M,Lomax AJ,Weber DC,Saito N,Burigo LN,Pfaffenberger A,Zhang Y

更新日期：2019-04-10 00:00:00