Monte Carlo calculation of beam quality correction factors for PTW cylindrical ionization chambers in photon beams.

abstract：:The clinical value of multiple b-value diffusion-weighted (DW) magnetic resonance imaging (MRI) has been shown in many studies. However, DW-MRI often suffers from low signal-to-noise ratio, especially at high b-values. To address this limitation, we present an image denoising method based on the concept of deep image ...

journal_title：Physics in medicine and biology

authors： Lin YC,Huang HM

更新日期：2020-05-11 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：:Sparse-view CT reconstruction algorithms via total variation (TV) optimize the data iteratively on the basis of a noise- and artifact-reducing model, resulting in significant radiation dose reduction while maintaining image quality. However, the piecewise constant assumption of TV minimization often leads to the appea...

journal_title：Physics in medicine and biology

authors： Niu S,Gao Y,Bian Z,Huang J,Chen W,Yu G,Liang Z,Ma J

更新日期：2014-06-21 00:00:00

abstract：:We examine how the choice of CT x-ray beam filtration and phantom size influences patient dose (D) to computed tomography dose index (CTDI) conversion factors (i.e. D/CTDI). The ratio of head to body phantom CTDI(w) for a defined scan technique is alpha, and the ratio of organ dose when the body filter is changed to t...

journal_title：Physics in medicine and biology

authors： Huda W,Sterzik A,Tipnis S

更新日期：2010-01-21 00:00:00

abstract：:It was observed that the radiation output of x-ray tubes falls off exponentially during an exposure with a time constant of about 120 ms. The equilibrium value is approximately 15% lower than that at the beginning of the exposure. The clinically noticeable consequences are discrepancies in x-ray generator calibration,...

journal_title：Physics in medicine and biology

authors： Brezovich IA,Barnes GT

更新日期：1980-03-01 00:00:00

abstract：:We present an automatic bi-objective parameter-tuning approach for inverse planning methods for high-dose-rate prostate brachytherapy, which aims to overcome the difficult and time-consuming manual parameter tuning that is currently required to obtain patient-specific high-quality treatment plans. We modelled treatmen...

journal_title：Physics in medicine and biology

authors： Maree SC,Bosman PAN,van Wieringen N,Niatsetski Y,Pieters BR,Bel A,Alderliesten T

更新日期：2020-04-02 00:00:00

abstract：:As the use of radiofrequency (RF) electromagnetic (EM) fields has increased along with increased use of wireless communication, the possible related health risks have also been widely discussed. One safety aspect is the interaction of medical implants and RF devices like mobile phones. In the literature, effects on ac...

journal_title：Physics in medicine and biology

authors： Virtanen H,Keshvari J,Lappalainen R

更新日期：2007-03-07 00:00:00

abstract：:The purpose of this work was to validate GATE-based clinical scale absorbed dose calculations in nuclear medicine dosimetry. GATE (version 6.2) and MCNPX (version 2.7.a) were used to derive dosimetric parameters (absorbed fractions, specific absorbed fractions and S-values) for the reference female computational model...

journal_title：Physics in medicine and biology

authors： Villoing D,Marcatili S,Garcia MP,Bardiès M

更新日期：2017-03-07 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

abstract：:A simple and fast, but sensitive TLD method for the measurement of energy and homogeneity of therapeutically used electron beams has been developed and tested. This method is based on the fact that when small thicknesses of high-Z absorbers such as lead are interposed in the high-energy electron beams, the transmitted...

journal_title：Physics in medicine and biology

authors： Pradhan AS,Quast U,Sharma PK

更新日期：1994-09-01 00:00:00

abstract：:Large blood vessels can produce steep temperature gradients in heated tissues leading to inadequate tissue temperatures during hyperthermia. This paper utilizes a finite difference scheme to solve the basic equations of heat transfer and fluid flow to model blood vessel cooling. Unlike previous formulations, heat tran...

journal_title：Physics in medicine and biology

authors： Kolios MC,Sherar MD,Hunt JW

更新日期：1995-04-01 00:00:00

abstract：:The widely applied single-interaction analytic expression characterizing the energy resolution component of the angular resolution precision for an electronically collimated point source is extended to include multiple-interaction Compton scatter sequences as well as sequences terminated by photoelectric absorption. T...

journal_title：Physics in medicine and biology

authors： Durkee JW Jr,Antich PP,Tsyganov EN,Constantinescu A,Kulkarni PV,Smith BJ,Arbique GM,Lewis MA,Nguyen T,Raheja A,Thambi G,Parkey RW

更新日期：1998-10-01 00:00:00

abstract：:Quantification of nuclear medicine image data is a prerequisite for personalized absorbed dose calculations and quantitative biodistribution studies. The spatial response of a detector is a governing factor affecting the accuracy of image quantification, and the aim of this work was to model this impact. To simulate s...

journal_title：Physics in medicine and biology

authors： Holstensson M,Partridge M,Buckley SE,Flux GD

更新日期：2010-03-21 00:00:00

abstract：:Speed of sound (SOS) measurements, typically made using 1 MHz broadband pulses, are increasingly used in the clinical diagnosis of bone disorders. Previous in vitro studies indicate that broadband ultrasound pulses are susceptible to distortion in cancellous bone, leading to imprecise arrival time and SOS measurements...

journal_title：Physics in medicine and biology

authors： Pollintine P,Haddaway MJ,Davie MW

更新日期：2000-07-01 00:00:00

abstract：:A method for quantifying the tissue sodium concentration (TSC) in the rat brain from ²³Na-MR images was developed. TSC is known to change in a variety of common human diseases and holds considerable potential to contribute to their study; however, its accurate measurement in small laboratory animals has been hindered ...

journal_title：Physics in medicine and biology

authors： Wetterling F,Tabbert M,Junge S,Gallagher L,Macrae IM,Fagan AJ

更新日期：2010-12-21 00:00:00

abstract：:In this paper, a coupled radiative transfer equation and diffusion approximation model is extended for light propagation in turbid medium with low-scattering and non-scattering regions. The light propagation is modelled with the radiative transfer equation in sub-domains in which the assumptions of the diffusion appro...

journal_title：Physics in medicine and biology

authors： Tarvainen T,Vauhkonen M,Kolehmainen V,Arridge SR,Kaipio JP

更新日期：2005-10-21 00:00:00

abstract：:In this work, a procedure, based on Monte Carlo techniques, to analyse the effect on the tumour control probability of the time interval between surgery and postoperative radiotherapy is presented. The approach includes the tumour growth as well as the survival of tumour cells undergoing fractionated radiotherapy. Bot...

journal_title：Physics in medicine and biology

authors： Al-Dweri FM,Guirado D,Lallena AM,Pedraza V

更新日期：2004-07-07 00:00:00

abstract：:An accurate, low noise estimate of photon attenuation in the subject is required for quantitative microPET studies of molecular tracer distributions in vivo. In this work, several transmission-based measurement techniques were compared, including coincidence mode with and without rod windowing, singles mode with two d...

journal_title：Physics in medicine and biology

authors： Lehnert W,Meikle SR,Siegel S,Newport D,Banati RB,Rosenfeld AB

更新日期：2006-08-21 00:00:00

abstract：:Although physical metrics can objectively characterize computed tomography (CT) image quality, quantitative approaches to predict human observer performance are more accurate and clinically relevant. This study compared a modified channelized Hotelling model observer (CHO) with human observers in a shape discriminatio...

journal_title：Physics in medicine and biology

authors： Zhang Y,Leng S,Yu L,Carter RE,McCollough CH

更新日期：2014-07-07 00:00:00

abstract：:We tested the ability of a single Compton camera (CC) to produce 3-dimensional (3D) images of prompt gammas (PGs) emitted during the irradiation of a tissue-equivalent plastic phantom with proton pencil beams for clinical doses delivered at clinical dose rates. PG measurements were made with a small prototype CC place...

journal_title：Physics in medicine and biology

authors： Draeger E,Mackin D,Peterson S,Chen H,Avery S,Beddar S,Polf JC

更新日期：2018-01-30 00:00:00

abstract：:109Cd K x-ray fluorescence (XRF) measurement systems from two research centres were used to measure tibia lead content in a population (n = 530) of young adults. The group mean bone lead contents (+/-SEM) determined by McMaster University (n = 214) and the University of Maryland (n = 316) were 2.80 +/- 0.51 and 2.33 +...

journal_title：Physics in medicine and biology

authors： McNeill FE,Stokes L,Chettle DR,Kaye WE

更新日期：1999-09-01 00:00:00

abstract：:In a previous paper the calibration of an isotropic light detector in clear media was described and validated. However, in most applications the detector is used to measure light distribution in turbid (scattering) media, that is, in tissues or tissue equivalent optical phantoms. Despite its small diameter (typically ...

journal_title：Physics in medicine and biology

authors： Marijnissen JP,Star WM

更新日期：2002-06-21 00:00:00

abstract：:Monte Carlo simulation techniques are applied to track the annihilation photons from positron decay, and store the photon histories. Reasonably realistic models of the isotope distribution in the brain and heart during typical PET studies, as well as the traditional phantoms used for measuring PET scanner performance ...

journal_title：Physics in medicine and biology

authors： Thompson CJ,Moreno-Cantu J,Picard Y

更新日期：1992-03-01 00:00:00

abstract：:In this note a technique is described for direct aperture optimization of components deliverable by a variable aperture collimator (VAC) for intensity-modulated radiation therapy. The first key result found was that, provided a large number of VAC components were selected for optimization, the resulting fluence profil...

journal_title：Physics in medicine and biology

authors： Webb S

更新日期：2004-03-07 00:00:00

abstract：:The Hug-Kellerer (H-K) equation is one of the earliest proposed radiation cell survival curves. We examine this equation in view of the recent perceived need for a universal cell survival curve which would be applicable to single radiation fractions at high doses. We derive relationships between the three parameters o...

journal_title：Physics in medicine and biology

authors： Ekstrand KE

更新日期：2010-05-21 00:00:00

abstract：:Contrast enhanced ultrasound (CEUS) and dynamic contrast enhanced ultrasound (DCE-US) can be used to provide information about the vasculature aiding diagnosis and monitoring of a number of pathologies including cancer. In the development of a CEUS imaging system, there are many choices to be made, such as whether to ...

journal_title：Physics in medicine and biology

authors： Moghimirad E,Bamber J,Harris E

更新日期：2019-04-23 00:00:00

abstract：:A technique is presented to allow a breathing pattern to be obtained from any multi-slice CT, cone-beam or other series of sequential chest x-ray image sets. The technique requires no extra signals to be recorded and does not need specific external or internal oscillating structures to be visible in the field of view....

journal_title：Physics in medicine and biology

authors： Kavanagh A,Evans PM,Hansen VN,Webb S

更新日期：2009-08-21 00:00:00

abstract：:In previous work we demonstrated the potential of positron emission tomography (PET) detectors with depth-of-interaction (DOI) encoding capability based on phosphor-coated crystals. A DOI resolution of 8 mm full-width at half-maximum was obtained for 20 mm long scintillator crystals using a delayed charge integration ...

journal_title：Physics in medicine and biology

authors： Roncali E,Phipps JE,Marcu L,Cherry SR

更新日期：2012-10-21 00:00:00

abstract：:In this paper we describe measurements of the contrast transfer function, modulation transfer function and point-spread function of an optical coherence tomography (OCT) imaging system through scattering layers having a dimension-less scattering depth over the range 0.2-6.9. The results were found to be insensitive to...

journal_title：Physics in medicine and biology

authors： Woolliams PD,Tomlins PH

更新日期：2011-05-07 00:00:00

abstract：:Heterogeneity corrections for radiotherapy dose calculations are based on the electron density of the disturbing heterogeneity. However, when CT planning a radiotherapy treatment, where metallic hip implants are present, considerable artefacts are seen in the images. Often, an additional problem arises whereby no info...

journal_title：Physics in medicine and biology

authors： Coolens C,Childs PJ

更新日期：2003-06-07 00:00:00