The recombination correction for an ionisation chamber exposed to pulsed radiation in a 'swept beam' technique. I. Theory.

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：:Respiratory-correlated cone-beam CT (CBCT) not only inhibits rapid scanning due to the slow speed of the LINAC head gantry rotation, but its implementation for routine patient imaging is impractical because of the high radiation dose delivered during the process. Digital tomosynthesis (DTS) is a potentially faster tec...

journal_title：Physics in medicine and biology

authors： Choi S,Lee S,Kang YN,Hsieh SS,Kim HJ

更新日期：2019-05-02 00:00:00

abstract：:Optically stimulated luminescent dosimeters (OSLDs) are becoming increasingly popular for measuring an absorbed dose in clinical radiotherapy. OSLDs have known energy dependence, and this is accounted for by either calibrating the OSLD with a specific nominal energy, or using a standard energy correction factor to acc...

journal_title：Physics in medicine and biology

authors： Scarboro SB,Followill DS,Kerns JR,White RA,Kry SF

更新日期：2012-05-07 00:00:00

abstract：:This study evaluates the performance of the Bruker positron emission tomograph (PET) insert combined with a BioSpec 70/30 USR magnetic resonance imaging (MRI) scanner using the manufacturer acceptance protocol and the NEMA NU 4-2008 for small animal PET. The PET insert is made of 3 rings of 8 monolithic LYSO crystals ...

journal_title：Physics in medicine and biology

authors： Gsell W,Molinos C,Correcher C,Belderbos S,Wouters J,Junge S,Heidenreich M,Vande Velde G,Rezaei A,Nuyts J,Cawthorne C,Cleeren F,Nannan L,Deroose CM,Himmelreich U,González Martínez AJ

更新日期：2020-06-26 00:00:00

abstract：:At present, only a correction factor for photon transmission, k(l), is systematically applied for the entrance diaphragm of free-air chamber standards for air kerma. In the present work, the Monte Carlo code PENELOPE is used to re-evaluate k(l) for the BIPM standards and new correction factors are calculated for photo...

journal_title：Physics in medicine and biology

authors： Burns DT,Kessler C

更新日期：2009-05-07 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：:This work applies a previously developed analytical algorithm to the reconstruction problem in a rotating multi-segment slant-hole (RMSSH) SPECT system. The RMSSH collimator has greater detection efficiency than the parallel-hole collimator with comparable spatial resolution at the expense of limited common volume-of-...

journal_title：Physics in medicine and biology

authors： Huang Q,Xu J,Tsui BM,Gullberg GT

更新日期：2009-07-07 00:00:00

abstract：:The goal of this study is to demonstrate the feasibility of a novel non-coplanar-arc optimization algorithm (CyberArc). This method aims to reduce the delivery time of conventional CyberKnife treatments by allowing for continuous beam delivery. CyberArc uses a 4 step optimization strategy, in which nodes, beams, and c...

journal_title：Physics in medicine and biology

authors： Kearney V,Cheung JP,McGuinness C,Solberg TD

更新日期：2017-06-26 00:00:00

abstract：:Modelling of inhaled particle deposition in the lungs potentially offers data relevant to assessing hazards from toxic inhaled particles, to studying mucus clearance or lung permeability by aerosol techniques, and to achieving better utilisation of drugs administered as aerosols. Analysis of published modelling studie...

journal_title：Physics in medicine and biology

authors： Agnew JE,Pavia D,Clarke SW

更新日期：1984-07-01 00:00:00

abstract：:To monitor and strategically control energy deposition in magnetic resonance imaging (MRI), measured as a specific absorption rate (SAR), numerical methods using generic human models have been employed to estimate worst-case values. Radiofrequency (RF) sequences are therefore often designed conservatively with large s...

journal_title：Physics in medicine and biology

authors： Jin J,Liu F,Weber E,Crozier S

更新日期：2012-12-21 00:00:00

abstract：:A method for the calculation of absorbed dose distributions of arbitrarily shaped electron beams is presented. Isodose distributions and output factors of treatment fields can be predicted with good accuracy, without the need for any dose measurement in the actual field. A Gaussian pencil beam model is employed with t...

journal_title：Physics in medicine and biology

authors： Bruinvis IA,Van Amstel A,Elevelt AJ,Van der Laarse R

更新日期：1983-06-01 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：:In dual energy x-ray absorptiometry (DXA) the photon attenuation is assumed to be similar in soft tissue overlying, adjacent to and inside the measured bone. In the calcaneal dual energy x-ray laser (DXL) technique, this assumption is not needed as attenuation by soft tissues at the local bone site is determined by co...

journal_title：Physics in medicine and biology

authors： Hakulinen MA,Saarakkala S,Töyräs J,Kröger H,Jurvelin JS

更新日期：2003-06-21 00:00:00

abstract：:In recent years, the Monte Carlo method has been used in a large number of research studies in radiation therapy. For applications such as treatment planning, it is essential to validate the dosimetric accuracy of the Monte Carlo simulations in heterogeneous media. The AAPM Report no 105 addresses issues concerning cl...

journal_title：Physics in medicine and biology

authors： Titt U,Sahoo N,Ding X,Zheng Y,Newhauser WD,Zhu XR,Polf JC,Gillin MT,Mohan R

更新日期：2008-08-21 00:00:00

abstract：:We have developed an iterative method to correct axial and tangential patient motion occurring during tomographic acquisition. The method uses axial images reconstructed from the uncorrected projection images, which are then forward projected to form a basis for registering the original planar images and, in the proce...

journal_title：Physics in medicine and biology

authors： Lee KJ,Barber DC

更新日期：1998-01-01 00:00:00

abstract：:An inverse radiation treatment planning algorithm for Sensus Healthcare's SculpturaTM electronic brachytherapy system has been designed. The algorithm makes use of simulated annealing to optimize the conformation number of the treatment plan. The highly anisotropic dose distributions produced by the SculpturaTM x-ray ...

journal_title：Physics in medicine and biology

authors： Badali DS,Vainer Y,Ellenor CW,Mitchell CR,Fishman K,Soro N,Price R,Funk T

更新日期：2021-01-11 00:00:00

abstract：:Joint space morphology can be indicative of the risk, presence, progression, and/or treatment response of disease or trauma. We describe a novel methodology of characterizing joint space morphology in high-resolution 3D images (e.g. cone-beam CT (CBCT)) using a model based on elementary electrostatics that overcomes a...

journal_title：Physics in medicine and biology

authors： Cao Q,Thawait G,Gang GJ,Zbijewski W,Reigel T,Brown T,Corner B,Demehri S,Siewerdsen JH

更新日期：2015-02-07 00:00:00

abstract：:Ultrasound-based elastography including strain elastography, acoustic radiation force impulse (ARFI) imaging, point shear wave elastography and supersonic shear imaging (SSI) have been used to differentiate breast tumors among other clinical applications. The objective of this study is to extend a previously published...

journal_title：Physics in medicine and biology

authors： Wang Y,Peng B,Jiang J

更新日期：2017-03-07 00:00:00

abstract：:Preclinical positron emission tomography, combined with magnetic resonance imaging (PET/MRI), is increasingly used as a tool to simultaneously characterize functional processes in vivo. Many emerging preclinical applications, however, are limited by PET detection sensitivity, especially when generating short imaging f...

journal_title：Physics in medicine and biology

authors： Selfridge AR,Cherry SR,Judenhofer MS

更新日期：2018-12-06 00:00:00

abstract：:The inadequate visibility of microcalcifications-small calcium deposits that cue radiologists to early stages of cancer-is a major limitation in current designs of dedicated breast computed tomography (bCT). This limitation has previously been attributed to the constituent components, spatial resolution, and utilized ...

journal_title：Physics in medicine and biology

authors： Ghazi P

更新日期：2020-12-04 00:00:00

abstract：:Poly(vinyl alcohol) cryogel, PVA-C, is presented as a tissue-mimicking material, suitable for application in magnetic resonance (MR) imaging and ultrasound imaging. A 10% by weight poly(vinyl alcohol) in water solution was used to form PVA-C, which is solidified through a freeze-thaw process. The number of freeze-thaw...

journal_title：Physics in medicine and biology

authors： Surry KJ,Austin HJ,Fenster A,Peters TM

更新日期：2004-12-21 00:00:00

abstract：:The treatment delivery time of intensity-modulated radiation therapy (IMRT) with a multileaf collimator (MLC) is generally longer than that of conventional radiotherapy. In theory, removing the flattening filter from the treatment head may reduce the beam-on time by enhancing the output dose rate, and then reduce the ...

journal_title：Physics in medicine and biology

authors： Fu W,Dai J,Hu Y,Han D,Song Y

更新日期：2004-04-21 00:00:00

abstract：:Previous treatment of cerebrospinal fluid (CSF) malignancies by intrathecal administration of (131)I-radiolabelled monoclonal antibodies has led to the assumption that more healthy tissue will be spared when a pure beta-emitter such as (90)Y replaces (131)I. The purpose of this study is to compare and quantitatively e...

journal_title：Physics in medicine and biology

authors： Mardirossian G,Hall M,Montebello J,Stevens P

更新日期：2006-01-07 00:00:00

abstract：:The Studsvik thermal-neutron facility was originally designed for neutron capture radiography (NCR) at high thermal-neutron fluence and low fast-neutron contamination. It has now been modified to permit irradiation of living cells and animals without the need for stopping and restarting the R2-0 reactor. Previous calc...

journal_title：Physics in medicine and biology

authors： Pettersson OA,Chiangmai SN,Grusell E,Larsson B

更新日期：1993-08-01 00:00:00

abstract：:Histotripsy is an ultrasound ablation method that depends on the initiation of a cavitation bubble cloud to fractionate soft tissue. Although previous work has provided significant insight into the process of intrinsic threshold histotripsy, the majority of these studies have used highly focused (i.e. f-number  <  0.6...

journal_title：Physics in medicine and biology

authors： Vlaisavljevich E,Gerhardson T,Hall T,Xu Z

更新日期：2017-02-21 00:00:00

abstract：:Magnetoencephalography (MEG) is a non-invasive functional imaging modality based on the measurement of the external magnetic field produced by neural current sources within the brain. The reconstruction of the underlying sources is a severely ill-posed inverse problem typically tackled using either low-dimensional par...

journal_title：Physics in medicine and biology

authors： Jerbi K,Mosher JC,Baillet S,Leahy RM

更新日期：2002-02-21 00:00:00

abstract：:The characteristics of an Elekta Precise treatment machine with a gating interface were investigated. Three detectors were used: a Farmer ionization chamber, a MatriXX ionization chamber array and an in-house, single pulse-measurement ionization chamber (IVC). Measurements were made of dosimetric accuracy, flatness an...

journal_title：Physics in medicine and biology

authors： Evans PM,Symonds-Tayler JR,Colgan R,Hugo GD,Letts N,Sandin C

更新日期：2010-04-21 00:00:00

abstract：:An extensive study on specific absorption rate (SAR) covering 720 simulations and 15 voxel models (18-105 kg) has been performed by applying the parallel finite-difference time-domain method. High-resolution whole-body models have been irradiated with plane waves from 300 MHz to 5 GHz by applying various incoming dire...

journal_title：Physics in medicine and biology

authors： Uusitupa T,Laakso I,Ilvonen S,Nikoskinen K

更新日期：2010-02-21 00:00:00

abstract：:The convergence rates of the fast Padé transform (FPT) and the fast Fourier transform (FFT) are compared. These two estimators are used to process a time-signal encoded at 4 T by means of one-dimensional magnetic resonance spectroscopy (MRS) for healthy human brain. It is found systematically that at any level of trun...

journal_title：Physics in medicine and biology

authors： Belkić D,Belkić K

更新日期：2005-09-21 00:00:00

abstract：:The peak CT number (CT) and full width at half maximum (FWHM) were obtained from the image profiles of aluminium of thickness ranging from 0.1-9.5 mm. The scans were performed at different fields of view (FOVs) and with different reconstruction algorithms ('bone' and 'standard'). Above 3 mm, CT and FWHM provide measur...

journal_title：Physics in medicine and biology

authors： Newman DL,Dougherty G,al Obaid A,al Hajrasy H

更新日期：1998-03-01 00:00:00