Ion-recombination correction for different ionization chambers in high dose rate flattening-filter-free photon beams.

abstract：:Under various clinical situations, it is desirable to modify the original treatment plan to better suit the clinical goals. In this work, a method to help physicians modify treatment plans based on their clinical preferences is proposed. The method uses a weighted quadratic dose objective function. The commonly used o...

journal_title：Physics in medicine and biology

authors： Wu C,Olivera GH,Jeraj R,Keller H,Mackie TR

更新日期：2003-08-07 00:00:00

abstract：:In magnetic resonance (MR) guided radiotherapy, the magnetic field-dependent change in the dose response of ionization chambers is typically included by means of a correction factor [Formula: see text]. This factor can be determined experimentally or calculated by means of Monte Carlo (MC) simulations. To date, a smal...

journal_title：Physics in medicine and biology

authors： Pojtinger S,Kapsch RP,Dohm OS,Thorwarth D

更新日期：2019-07-04 00:00:00

abstract：:Ultraviolet (UV) treatment dose is determined by the length of time that a patient spends in a phototherapy cabin. The output from UV fluorescent lamps declines with use and a method is needed to compensate for the change in irradiance and to identify and replace any lamps that fail. The decline in lamp output with ag...

journal_title：Physics in medicine and biology

authors： Amatiello H,Martin CJ

更新日期：2006-01-21 00:00:00

abstract：:Diffuse optical tomography is an imaging technique whereby spatial maps of absorption and scattering coefficients are derived from the characteristics of multiply scattered light transmitted through the object. The system described here used four intensity-modulated light sources and measurements of the intensity and ...

journal_title：Physics in medicine and biology

authors： Pogue BW,Patterson MS,Jiang H,Paulsen KD

更新日期：1995-10-01 00:00:00

abstract：:Instead of performing a numerical deconvolution, we propose to use a linear piecewise-continuous model of the renal impulse response function for parametric fitting of renal scintigraphy data, to obtain clinically useful renal parameters. The strengths of the present model are its simplicity and speed of computation, ...

journal_title：Physics in medicine and biology

authors： Zhang JL,Zhang L,Koh TS,Shuter B

更新日期：2003-06-21 00:00:00

abstract：:Practical dosimeters in brachytherapy, such as thermoluminescent dosimeters (TLD) and diodes, are usually calibrated against low-energy megavoltage beams. To measure absolute dose rate near a brachytherapy source, it is necessary to establish the energy response of the detector relative to that of the calibration ener...

journal_title：Physics in medicine and biology

authors： Das RK,Li Z,Perera H,Williamson JF

更新日期：1996-06-01 00:00:00

abstract：:We give an overview of the role of Physics in Medicine and Biology in the development of tomographic reconstruction algorithms. We focus on imaging modalities involving ionizing radiation, CT, PET and SPECT, and cover a wide spectrum of reconstruction problems, starting with classical 2D tomography in the 1970s up to ...

journal_title：Physics in medicine and biology

authors： Defrise M,Gullberg GT

更新日期：2006-07-07 00:00:00

abstract：:In the IAEA TRS-381 protocol, k(cel) and p(cel) account for the central electrode perturbation during the air kerma chamber calibration and the in-phantom measurements. The values of these correction factors are based mainly on Monte Carlo simulations. In the present work experimental data on k(cel) and p(cel) for the...

journal_title：Physics in medicine and biology

authors： Palm A,Mattsson O

更新日期：1999-05-01 00:00:00

abstract：:Measurements of patient entrance surface dose rate provide valuable data for interpreting results from dose-area product studies on fluoroscopic x-ray equipment. Methods for measurement of entrance surface dose rate with backscatter and incident dose rate without backscatter have been investigated. Entrance surface do...

journal_title：Physics in medicine and biology

authors： Martin CJ

更新日期：1995-05-01 00:00:00

abstract：:Histotripsy is a therapeutic ultrasound modality under development to liquefy tissue mechanically via bubble clouds. Image guidance of histotripsy requires both quantification of the bubble cloud activity and accurate delineation of the treatment zone. In this study, magnetic resonance (MR) and diagnostic ultrasound i...

journal_title：Physics in medicine and biology

authors： Anthony GJ,Bollen V,Hendley S,Antic T,Sammet S,Bader KB

更新日期：2019-05-02 00:00:00

abstract：:The purpose of this work is to develop and test a method to estimate the relative and absolute absorbed radiation dose from axial and spiral CT scans using a Monte Carlo approach. Initial testing was done in phantoms and preliminary results were obtained from a standard mathematical anthropomorphic model (MIRD V) and ...

journal_title：Physics in medicine and biology

authors： Jarry G,DeMarco JJ,Beifuss U,Cagnon CH,McNitt-Gray MF

更新日期：2003-08-21 00:00:00

abstract：:This paper reports a theoretical study on the distribution of blood flow in the human cardiovascular system when one or more blood vessels are affected by stenosis. The analysis employs a mathematical model of the entire system based on the finite element method. The arterial-venous network is represented by a large n...

journal_title：Physics in medicine and biology

authors： Sud VK,Srinivasan RS,Charles JB,Bungo MW

更新日期：1993-03-01 00:00:00

abstract：:We present a new image reconstruction algorithm for helical cone-beam computed tomography (CT). This algorithm is designed for data collected at or near maximum pitch, and provides a theoretically exact and stable reconstruction while beneficially using all measured data. The main operations involved are a differentia...

journal_title：Physics in medicine and biology

authors： Schöndube H,Stierstorfer K,Noo F

更新日期：2009-08-07 00:00:00

abstract：:A silicon semiconductor photodiode was used to measure the TL-signal of TLD-300 (CaF2:Tm) detectors irradiated with 60Co gamma rays and 226Ra alpha particles. The applied dose values varied from 0.12 to 14.3 Gy for gamma rays and from about 50 to 300 Gy for alpha particles. Because of the infrared sensitivity of the p...

journal_title：Physics in medicine and biology

authors： Meissner P,Jacob M,Rassow J

更新日期：1988-12-01 00:00:00

abstract：:A number of radiation-therapy-related uses based on a commercially available spreadsheet program have been developed at our facility. The graphics and display capabilities inherent in these spreadsheet programs allow for concise visual results. The spreadsheets are used as an independent check for several types of rad...

journal_title：Physics in medicine and biology

authors： Balog JP,Sibata CH,Podgorsak MB,Shin KH

更新日期：1995-06-01 00:00:00

abstract：:A new system has been designed and built to validate the concept of 3D computerized angiography (CA). This system can acquire a set of 2D digital subtracted angiography images while rotating around a patient and then, using these images, reconstruct a 3D representation of the opacified vasculature. The design principl...

journal_title：Physics in medicine and biology

authors： Saint-Félix D,Trousset Y,Picard C,Ponchut C,Roméas R,Rougée A

更新日期：1994-03-01 00:00:00

abstract：:Tumour histological grade has prognostic implications in breast cancer. Tumour features in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and T2-weighted (T2W) imaging can provide related and complementary information in the analysis of breast lesions to improve MRI-based histological status prediction...

journal_title：Physics in medicine and biology

authors： Fan M,Liu Z,Xie S,Xu M,Wang S,Gao X,Li L

更新日期：2019-10-23 00:00:00

abstract：:Backscatter factors for orthovoltage x-ray beams are fitted with the expression BSF = 1 + ms/(s + n), where s is field size and m and n are adjustable parameters. The accuracy is better than 0.5%. Good results were also obtained for Cs-137 gamma rays at depth 0.12 cm and Co-60 gamma rays at depth 0.5 cm using the same...

journal_title：Physics in medicine and biology

authors： Xiao Y,Bjärngard B

更新日期：1998-05-01 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：:In BANG gel dosimetry, the spin-spin relaxation rate, R2 = I/T2, is related to the radiation dose that has been delivered to the gel phantom. R2 is calculated by fitting the pixel intensities of a set of differently T2-weighted base images. In gel dosimetry for radiotherapy, an accuracy of 5% in dose and 3 mm spatiall...

journal_title：Physics in medicine and biology

authors： De Deene Y,De Wagter C,De Neve W,Achten E

更新日期：2000-07-01 00:00:00

abstract：:Recently, the initial 2D physical characterization of a small-diameter positron emission tomograph, designed specifically for scanning of small laboratory animals, was reported. The physical characteristics of the tomograph operating in 3D mode have now been measured and compared to those obtained in 2D mode. In 3D, t...

journal_title：Physics in medicine and biology

authors： Bloomfield PM,Myers R,Hume SP,Spinks TJ,Lammertsma AA,Jones T

更新日期：1997-02-01 00:00:00

abstract：:With the development of laser technology, laser-driven proton acceleration provides a new method for proton tumor therapy. However, it has not been applied in practice because of the wide and decreasing energy spectrum of laser-accelerated proton beams. In this paper, we propose an analytical model to reconstruct the ...

journal_title：Physics in medicine and biology

authors： Tao L,Zhu K,Zhu J,Xu X,Lin C,Ma W,Lu H,Zhao Y,Lu Y,Chen JE,Yan X

更新日期：2017-07-07 00:00:00

abstract：:The fluence to organ-dose and effective-dose conversion coefficients for neutrons and protons with energies up to 100 GeV was calculated using the PHITS code coupled to male and female adult reference computational phantoms, which are to be released as a common ICRP/ICRU publication. For the calculation, the radiation...

journal_title：Physics in medicine and biology

authors： Sato T,Endo A,Zankl M,Petoussi-Henss N,Niita K

更新日期：2009-04-07 00:00:00

abstract：:Micro-CT is widely used in preclinical studies, generating substantial interest in extending its capabilities in functional imaging applications such as blood perfusion and cardiac function. However, imaging cardiac structure and function in mice is challenging due to their small size and rapid heart rate. To overcome...

journal_title：Physics in medicine and biology

authors： Holbrook M,Clark DP,Badea CT

更新日期：2018-01-09 00:00:00

abstract：:This is a review of the relatively recently developed field of intravascular brachytherapy of coronary arteries. It presents a brief overview of the discipline of coronary angioplasty describing the problem of restenosis and discusses the potential for ionizing radiation to overcome this problem. It examines the vario...

journal_title：Physics in medicine and biology

authors： Fox RA

更新日期：2002-02-21 00:00:00

abstract：:This paper presents a method to obtain the pencil-beam kernels that characterize a megavoltage photon beam generated in a flattening filter free (FFF) linear accelerator (linac) by deconvolution from experimental measurements at different depths. The formalism is applied to perform independent dose calculations in mod...

journal_title：Physics in medicine and biology

authors： Azcona JD,Barbés B,Wang L,Burguete J

更新日期：2016-01-07 00:00:00

abstract：:We report a new preparative method for providing contrast through reduction in electron density that is uniquely suited for propagation-based differential x-ray phase contrast imaging. The method, which results in an air or fluid filled vasculature, makes possible visualization of the smallest microvessels, roughly do...

journal_title：Physics in medicine and biology

authors： Laperle CM,Hamilton TJ,Wintermeyer P,Walker EJ,Shi D,Anastasio MA,Derdak Z,Wands JR,Diebold G,Rose-Petruck C

更新日期：2008-12-07 00:00:00

abstract：:Four-dimensional (4D) methods strive to achieve highly conformal radiotherapy, particularly for lung and breast tumours, in the presence of respiratory-induced motion of tumours and normal tissues. Four-dimensional radiotherapy accounts for respiratory motion during imaging, planning and radiation delivery, and requir...

journal_title：Physics in medicine and biology

authors： Vedam SS,Keall PJ,Kini VR,Mostafavi H,Shukla HP,Mohan R

更新日期：2003-01-07 00:00:00

abstract：:A method to determine the spectrum of a clinical photon beam from measured depth-dose data is described. At shallow depths, where the range of Compton-generated electrons increases rapidly with photon energy, the depth dose provides the information to discriminate the spectral contributions. To minimize the influence ...

journal_title：Physics in medicine and biology

authors： Bloch P,Altschuler MD,Bjärngard BE,Kassaee A,McDonough J

更新日期：2000-01-01 00:00:00

abstract：:Ion beam radiotherapy exploits the finite range of ion beams and the increased dose deposition of ions toward the end of their range in material. This results in high dose conformation to the target region, which can be further increased using scanning ion beams. The standard method for patient-plan verification in io...

journal_title：Physics in medicine and biology

authors： Martišíková M,Brons S,Hesse BM,Jäkel O

更新日期：2013-03-21 00:00:00