Isotope computed tomography using cone-beam geometry: a comparison of two reconstruction algorithms.

abstract：:A new component module (CM), designated DYNVMLC, was developed to fully model the geometry of the Varian Millennium 120 leaf collimator using the BEAMnrc Monte Carlo code. The model includes details such as the leaf driving screw hole, support railing groove and leaf tips. Further modifications also allow sampling of ...

journal_title：Physics in medicine and biology

authors： Heath E,Seuntjens J

更新日期：2003-12-21 00:00:00

abstract：:This study aims at investigating in real-time the structural and dynamical changes occurring in an ex vivo tissue during a microwave thermal ablation (MTA) procedure. The experimental set-up was based on ex vivo liver tissue inserted in a dedicated box, in which 3 fibre-optic (FO) temperature probes were introduced to...

journal_title：Physics in medicine and biology

authors： Strigari L,Minosse S,D'Alessio D,Farina L,Cavagnaro M,Cassano B,Pinto R,Vallati G,Lopresto V

更新日期：2019-05-31 00:00:00

abstract：:Coronary computed tomography angiography (cCTA) is a commonly used imaging modality for the evaluation of coronary artery disease. cCTA is generally reconstructed in multiple cardiac phases because different coronary arteries may be better visualized in some phases than in others due to the periodic cardiac motion. We...

journal_title：Physics in medicine and biology

authors： Hadjiiski L,Zhou C,Chan HP,Chughtai A,Agarwal P,Kuriakose J,Kazerooni E,Wei J,Patel S

更新日期：2014-08-21 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：:A micro-multileaf collimator (microMLC) for stereotactic radiosurgery is used for determination of the spatial intensity distribution of the photon source of a linear accelerator. The method is based on grid field dose measurements using film dosimetry and is easy to perform. Since the microMLC does not allow 'direct'...

journal_title：Physics in medicine and biology

authors： Treuer H,Hoevels M,Luyken K,Hunsche S,Kocher M,Müller RP,Sturm V

更新日期：2003-08-07 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：:The possible use of fluorescence bronchoscopy for localization of bronchogenic tumours at the carcinoma in situ stage has been investigated. The target lesion is 80 micrometer thick with a mass of 250 microgram, containing 250 pg of haematoporphyrin derivative. The injected haematoporphyrin-derivative is preferentiall...

journal_title：Physics in medicine and biology

authors： Profio AE,Doiron DR

更新日期：1977-09-01 00:00:00

abstract：:Optical experiments are described for measuring the attenuation characteristics of breast tissues at visible and near-infrared wavelengths. Total attenuation coefficients post mortem were measured directly in thin tissue sections. They are usually within the range from 10 to 30 mm-1, are rather higher in fat than in f...

journal_title：Physics in medicine and biology

authors： Key H,Davies ER,Jackson PC,Wells PN

更新日期：1991-05-01 00:00:00

abstract：:Measuring spin-spin relaxation times (T2) by quantitative MR imaging represents a potentially efficient tool to evaluate the physicochemical properties of various media. However, noise in MR images is responsible for uncertainties in the determination of T2 relaxation times, which limits the accuracy of parametric tis...

journal_title：Physics in medicine and biology

authors： Gensanne D,Josse G,Lagarde JM,Vincensini D

更新日期：2006-06-07 00:00:00

abstract：:This is a proof of principle study on an algorithm for optimizing external beam radiotherapy in terms of both photon beamlet energy and fluence. This simultaneous beamlet energy and fluence optimization is denoted modulated photon radiotherapy (XMRT). XMRT is compared with single-energy intensity modulated radiotherap...

journal_title：Physics in medicine and biology

authors： McGeachy P,Villarreal-Barajas JE,Zinchenko Y,Khan R

更新日期：2016-02-21 00:00:00

abstract：:Input functions required for positron emission tomography (PET) tracer kinetic modeling are often obtained from arterial blood. In some situations, using short-lived radiotracers, e.g. [(15)O]water, rapid sample handling is required. A method used at several facilities is to pump blood through a detector system at a c...

journal_title：Physics in medicine and biology

authors： Laymon CM,Sashin D,Carney JP,Ruszkiewicz J,Altenburger D,Becker CR,Lopresti BJ,Mason NS,Mountz JM,Price JC,Schavey R,Mathis CA

更新日期：2008-01-21 00:00:00

abstract：:A photon diffusion model has been developed to calculate the steady-state spatially resolved fluorescence from pencil beam excitation in layered tissue. The model allows the calculation of both the excitation reflectance and the fluorescence escape for an arbitrary continuous depth distribution of tissue optical prope...

journal_title：Physics in medicine and biology

authors： Hyde DE,Farrell TJ,Patterson MS,Wilson BC

更新日期：2001-02-01 00:00:00

abstract：:The measurement of output factors (OF) for the small photon beams generated by Leksell Gamma Knife® (LGK) radiotherapy units is a challenge for the physicist due to the under or over estimation of these factors by a vast majority of the detectors commercially available. Output correction factors, introduced in the int...

journal_title：Physics in medicine and biology

authors： Benmakhlouf H,Johansson J,Paddick I,Andreo P

更新日期：2015-05-21 00:00:00

abstract：:A novel digital x-ray detector has been assembled. The imaging system is based on a phosphor-coated charge-coupled device (CCD) obtained by direct deposition of a gadolinium oxysulphide scintillator onto the detector surface. The modulation transfer function has been measured along the two directions of the digital co...

journal_title：Physics in medicine and biology

authors： Gambaccini M,Taibi A,Del Guerra A,Marziani M,Tuffanelli A

更新日期：1996-12-01 00:00:00

abstract：:Factors affecting the accuracy of the in vivo measurement of cutaneous pigments and blood oxygenation by reflectance spectrophotometry have been examined. It was found that stray light, the amounts of haemoglobin and melanin, and the level of blood oxygenation all contributed to the measured reflectance and had to be ...

journal_title：Physics in medicine and biology

authors： Hajizadeh-Saffar M,Feather JW,Dawson JB

更新日期：1990-09-01 00:00:00

abstract：:This paper introduces a novel compartmental model describing the excretion of 18F-fluoro-deoxyglucose (FDG) in the renal system and a numerical method based on the maximum likelihood for its reduction. This approach accounts for variations in FDG concentration due to water re-absorption in renal tubules and the increa...

journal_title：Physics in medicine and biology

authors： Garbarino S,Caviglia G,Sambuceti G,Benvenuto F,Piana M

更新日期：2014-05-21 00:00:00

abstract：:Diffraction-enhanced imaging (DEI) is a new x-ray imaging modality that has been shown to enhance contrast between normal and cancerous breast tissues. In this study, diffraction-enhanced imaging in computed tomography (DEI-CT) mode was used to quantitatively characterize the refraction contrasts of the organized stru...

journal_title：Physics in medicine and biology

authors： Kao T,Connor D,Dilmanian FA,Faulconer L,Liu T,Parham C,Pisano ED,Zhong Z

更新日期：2009-05-21 00:00:00

abstract：:Microbeam radiation therapy (MRT) is a pre-clinical, spatially-fractionated treatment modality noted for its ability to achieve a large differential response between normal and tumoral tissues. In the present study, TOPAS Monte Carlo (MC) simulations were used to optimize the design of a compact, affordable multi-slit...

journal_title：Physics in medicine and biology

authors： Esplen NM,Chergui L,Johnstone CD,Bazalova-Carter M

更新日期：2018-08-29 00:00:00

abstract：:The dynamic magnetization of immobilized spherical single-domain magnetic nanoparticles (MNPs) with uniaxial or cubic magnetocrystalline anisotropy was studied computationally by executing simulations based on the Landau-Lifshitz-Gilbert (LLG) equation. For situations when a static magnetic field was suddenly applied ...

journal_title：Physics in medicine and biology

authors： Zhao Z,Garraud N,Arnold DP,Rinaldi C

更新日期：2020-01-17 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：:We have investigated the tongue-and-groove effect on the IMRT dose distributions for a Varian MLC. We have compared the dose distributions calculated using the intensity maps with and without the tongue-and-groove effect. Our results showed that, for one intensity-modulated treatment field, the maximum tongue-and-groo...

journal_title：Physics in medicine and biology

authors： Deng J,Pawlicki T,Chen Y,Li J,Jiang SB,Ma CM

更新日期：2001-04-01 00:00:00

abstract：:A method will be described for determining the centre of rotation of a mechanically scanned reflection ultrasound computed tomography system. It is based on the principle of obtaining opposing images of a test object containing many point targets. The method is automatic in the sense that the centre of rotation is cal...

journal_title：Physics in medicine and biology

authors： Jago JR

更新日期：1994-12-01 00:00:00

abstract：:Due to high noise levels in the voxel kinetics, development of reliable parametric imaging algorithms remains one of most active areas in dynamic brain PET imaging, which in the vast majority of cases involves receptor/transporter studies with reversibly binding tracers. As such, the focus of this work has been to dev...

journal_title：Physics in medicine and biology

authors： Rahmim A,Zhou Y,Tang J,Lu L,Sossi V,Wong DF

更新日期：2012-02-07 00:00:00

abstract：:The architecture of multi-layer imagers (MLIs) can be exploited to provide megavoltage spectral imaging (MVSPI) for specific imaging tasks. In the current work, we investigated bone suppression and gold fiducial contrast enhancement as two clinical tasks which could be improved with spectral imaging. A method based on...

journal_title：Physics in medicine and biology

authors： Myronakis M,Hu YH,Fueglistaller R,Wang A,Baturin P,Huber P,Morf D,Star-Lack J,Berbeco R

更新日期：2018-05-10 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：:None of the existing protocols or codes of practice for high-energy electron dosimetry take any account of the accelerator-generated bremsstrahlung always present in electron beams. This results in a systematic error in the derivation of the absorbed dose. The purpose of this study is to draw attention to this omissio...

journal_title：Physics in medicine and biology

authors： Klevenhagen SC

更新日期：1994-07-01 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：:For conventional irradiation devices, the radiation isocenter accuracy is determined by star shot measurements on films. In magnetic resonance (MR)-guided radiotherapy devices, the results of this test may be altered by the magnetic field and the need to align the radiation and imaging isocenter may require a modifica...

journal_title：Physics in medicine and biology

authors： Dorsch S,Mann P,Lang C,Haering P,Runz A,Karger CP

更新日期：2018-05-29 00:00:00

abstract：:A mathematical transcription of the intrinsic circuit of the CA1 region of the rat dorsal hippocampus was made and the model parameters adjusted according to experimental data from intracellular recordings and single channel kinetics. This model was able to simulate well the profile of the field potentials recorded ex...

journal_title：Physics in medicine and biology

authors： Almeida AC,Fernandes de Lima VM,Infantosi AF

更新日期：1998-09-01 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