Acceptance testing and quality assurance of automated scanning film densitometers used in the dosimetry of electron and photon therapy beams.

abstract：PURPOSE:To investigate the acoustic radiation due to eddy current-cryostat interactions and perform a qualitative analysis on noise reduction methods. METHODS:In order to evaluate the sound pressure level (SPL) of the eddy current induced warm bore wall vibration, a Finite Element (FE) model was created to simulate th...

journal_title：Medical physics

authors： Wang Y,Liu F,Zhou X,Li Y,Crozier S

更新日期：2017-06-01 00:00:00

abstract：:A method is described for calibration of 192Ir high-dose-rate (HDR) brachytherapy afterloading systems. Since NIST does not offer calibration of ionization chambers with the gamma-ray spectrum of iridium-192, an interpolation procedure is employed, using calibrations above (137Cs, 662 keV) and below (250 kVcp, 146-keV...

journal_title：Medical physics

authors： Goetsch SJ,Attix FH,Pearson DW,Thomadsen BR

更新日期：1991-05-01 00:00:00

abstract：PURPOSE:The aim of this paper is to investigate the accuracy of a laser∕camera surface imaging system (Sentinel) when used on patients treated in the thorax or pelvic regions and to evaluate system employment conditions and patient setup procedures that provide more accurate results. METHODS:The system was tested on t...

journal_title：Medical physics

authors： Pallotta S,Simontacchi G,Marrazzo L,Ceroti M,Paiar F,Biti G,Bucciolini M

更新日期：2013-01-01 00:00:00

abstract：:Currently, two classes of the computational phantoms have been developed for dosimetry calculation: (1) stylized (or mathematical) and (2) voxel (or tomographic) phantoms describing human anatomy through mathematical surface equations and three-dimensional labeled voxel matrices, respectively. Mathematical surface equ...

journal_title：Medical physics

authors： Lee C,Lodwick D,Williams JL,Bolch WE

更新日期：2008-06-01 00:00:00

abstract：:An artificial neural network using input data derived from attenuation measurements was trained to generate spectral profiles (relative number of photons versus energy). Once the relative spectral distribution is reconstructed, absolute spectra (number of photons per unit exposure spectral distribution is reconstructe...

journal_title：Medical physics

authors： Boone JM

更新日期：1990-07-01 00:00:00

abstract：PURPOSE:To develop a real-time markerless 3D tumor tracking using kilovoltage (kV) cone-beam CT (CBCT) projection images during volumetric modulated arc therapy (VMAT) treatment of lung tumors. METHODS:The authors have developed a method to identify the position of lung tumors during VMAT treatment, where the current ...

journal_title：Medical physics

authors： Zhuang L,Liang J,Yan D,Zhang T,Marina O,Ionascu D

更新日期：2013-10-01 00:00:00

abstract：:Frequent and repeated imaging procedures such as those performed in image-guided radiotherapy (IGRT) programs may add significant dose to radiosensitive organs of radiotherapy patients. It has been shown that kV-CBCT results in doses to bone that are up to a factor of 3-4 higher than those in surrounding soft tissue. ...

journal_title：Medical physics

authors： Ding GX,Pawlowski JM,Coffey CW

更新日期：2008-12-01 00:00:00

abstract：:An overall practical dosimetric study of a 10-MV photon beam produced by a Varian Clinac-18 linear accelerator is presented. In particular measurements were made to provide data which could be utilized in computerized dosage calculations using the concept of dividing the radiation beam into primary and scatter compone...

journal_title：Medical physics

authors： Van Dyk J

更新日期：1977-03-01 00:00:00

abstract：:Transmission data for 4-MV bremsstrahlung beams have been measured with a combination of lead and aluminum attenuators. From these data, the original energy spectra have been reconstructed using an iterative least-squares technique, previously evaluated by simulation studies. The spectra on the central axis for three ...

journal_title：Medical physics

authors： Huang PH,Kase KR,Bjärngard BE

更新日期：1983-11-01 00:00:00

abstract：PURPOSE:Radiochromic film provides dose measurement at high spatial resolution, but often is not preferred for routine evaluation of patient-specific intensity modulated radiation therapy (IMRT) plans owing to ease-of-use factors. The authors have established an efficient protocol that combines calibration and measurem...

journal_title：Medical physics

authors： Lewis D,Micke A,Yu X,Chan MF

更新日期：2012-10-01 00:00:00

abstract：PURPOSE:The segmentation accuracy of medical images was improved by increasing the number of training samples using a local image warping technique. The performance of the proposed method was evaluated in the segmentation of breast masses, prostate and brain tumors, and lung nodules. METHODS:We propose a simple data a...

journal_title：Medical physics

authors： Liu H,Cao H,Song E,Ma G,Xu X,Jin R,Liu T,Liu L,Liu D,Hung CC

更新日期：2020-12-10 00:00:00

abstract：PURPOSE:Intensity modulated proton therapy (IMPT) is sensitive to errors, mainly due to high stopping power dependency and steep beam dose gradients. Conventional margins are often insufficient to ensure robustness of treatment plans. In this article, a method is developed that takes the uncertainties into account duri...

journal_title：Medical physics

authors： Fredriksson A,Forsgren A,Hårdemark B

更新日期：2011-03-01 00:00:00

abstract：PURPOSE:Variations during breast tissue development can influence later breast cancer risk. In particular, prolonged nulliparity increases risk. The authors used optical spectroscopy to compare breast tissue in 115 nulliparous women aged 31-40 (group 2) to 140 nulliparous women aged 18-21 (group 1), and also to 36 paro...

journal_title：Medical physics

authors： Knight JA,Blackmore KM,Wong J,Tharmalingam S,Lilge L

更新日期：2010-02-01 00:00:00

abstract：:New radiation therapy techniques such as IMRT present significant efficiency due to their highly conformal dose distributions. A consequence of the complexity of their dose distributions (high gradients, small irradiation fields, low dose distribution, ...) is the requirement for better precision quality assurance tha...

journal_title：Medical physics

authors： Frelin AM,Fontbonne JM,Ban G,Colin J,Labalme M,Batalla A,Vela A,Boher P,Braud M,Leroux T

更新日期：2008-05-01 00:00:00

abstract：:Multielectrode cochlear implantation is the most effective treatment for profound sensorineural hearing loss. In vivo three-dimensional 3-D localization of cochlear implant electrodes is important for modeling of the electrical field in the cochlea, design of electrode arrays, and may improve speech processor programm...

journal_title：Medical physics

authors： Yang S,Wang G,Skinner MW,Rubinstein JT,Vannier MW

更新日期：2000-04-01 00:00:00

abstract：PURPOSE:In previous work, the authors developed and demonstrated the concept of an image reconstruction procedure aimed to unify gated and dynamic nuclear cardiac imaging, which the authors have termed five-dimensional (5D) SPECT. Gated imaging permits the clinician to evaluate wall motion and, through the use of stres...

journal_title：Medical physics

authors： Niu X,Yang Y,King MA,Wernick MN

更新日期：2010-09-01 00:00:00

abstract：:The use of the stable isotope 48Ca as a tracer in biological systems has been studied. Determination of 48Ca concentrations in samples was accomplished by proton activation via the (p,n) reaction with subsequent measurement of gamma-ray spectra from 44-h 48Sc and 4-h 44Sc. With protons of about 5.5 MeV and a Ge(Li) ga...

journal_title：Medical physics

authors： Edwards FM,Kraushaar JJ,Ristinen RA,Rudolph H

更新日期：1977-01-01 00:00:00

abstract：PURPOSE:This work describes the performance characterization of a cone-beam CT-guided radiosurgery device, the Gamma Knife® Icon™. METHODS:The performance tests have been categorized into: (a) image quality and mechanical integrity; (b) image coregistration fidelity; (c) adaptive treatment delivery quality; (d) high d...

journal_title：Medical physics

authors： Sarfehnia A,Ruschin M,Chugh B,Yeboah C,Becker N,Cho YB,Lee Y

更新日期：2018-06-29 00:00:00

abstract：:The purpose of this work is to show the feasibility of using in vivo proton radiography of a radiotherapy patient for the patient individual optimization of the calibration from CT-Hounsfield units to relative proton stopping power. Water equivalent tissue (WET) calibrated proton radiographs of a dog patient treated f...

journal_title：Medical physics

authors： Schneider U,Pemler P,Besserer J,Pedroni E,Lomax A,Kaser-Hotz B

更新日期：2005-01-01 00:00:00

abstract：PURPOSE:To investigate whether functionally-weighted dose-volume histogram (DVH) parameters are more predictive of radiation-induced pneumonitis (RP) than standard parameters such as V20 and mean lung dose (MLD). MATERIALS AND METHODS:A retrospective chart review identified 26 patients who received curative-intent rad...

journal_title：Medical physics

authors： Hoover D,Reid RH,Rodrigues G,Wong E,Stitt L,Yaremko BP

更新日期：2012-07-01 00:00:00

abstract：PURPOSE:The need for an accurate lesion segmentation tool in 18FDG PET is a prerequisite for the estimation of lesion response to therapy, for radionuclide dosimetry, and for the application of 18FDG PET to radiotherapy planning. In this work, the authors have developed an iterative method based on a mathematical fit d...

journal_title：Medical physics

authors： Nehmeh SA,El-Zeftawy H,Greco C,Schwartz J,Erdi YE,Kirov A,Schmidtlein CR,Gyau AB,Larson SM,Humm JL

更新日期：2009-10-01 00:00:00

abstract：PURPOSE:The implementation of an accurate beam model is an integral part of the commissioning of any planning system. This process is especially challenging in the case of IMRT beam models owing to the complexity of small field sizes and MLC leaf-end and tongue-and-groove effects. The question of how to judge the quali...

journal_title：Medical physics

authors： Veltchev I,Fourkal E,Price R,Ma C

更新日期：2012-06-01 00:00:00

abstract：:In a practical classifier design problem, the true population is generally unknown and the available sample is finite-sized. A common approach is to use a resampling technique to estimate the performance of the classifier that will be trained with the available sample. We conducted a Monte Carlo simulation study to co...

journal_title：Medical physics

authors： Sahiner B,Chan HP,Hadjiiski L

更新日期：2008-04-01 00:00:00

abstract：:Nuclear Magnetic Resonance (NMR) permits the noninvasive measurement of blood flow signals unimpaired by clothes, bandages, casts, etc. The cylindrical crossed-coil NMR blood flowmeter was used to measure blood flow through a cross-section of the human forearm. Two calibration procedures are described: one for pulsati...

journal_title：Medical physics

authors： Salles-Cunha SX,Halbach RE,Battocletti JH,Sances A Jr

更新日期：1981-07-01 00:00:00

abstract：:The mixed-field dosimetry for 252Cf Applicator Tube (AT) type medical sources available from Oak Ridge National Laboratory (ORNL) has been characterized using ionization chambers, a GM counter, and Monte Carlo methods. Unlike the AAPM Task Group No. 43 (TG-43), specification of dose to muscle instead of water is recom...

journal_title：Medical physics

authors： Rivard MJ

更新日期：1999-08-01 00:00:00

abstract：PURPOSE:The aim of this work was to provide a novel description of how the radiotherapy community configures treatment planning system (TPS) radiation beam models for clinically used treatment machines. Here we describe the results of a survey of self-reported TPS beam modeling parameter values across different C-arm l...

journal_title：Medical physics

authors： Glenn MC,Peterson CB,Followill DS,Howell RM,Pollard-Larkin JM,Kry SF

更新日期：2020-01-01 00:00:00

abstract：:The nuclear magnetic resonance phenomenon has given rise to both magnetic resonance imaging, which yields morphologic data, and magnetic resonance spectroscopy (MRS), which yields chemical data. In humans these data are derived principally from the resonances of the hydrogen nucleus in the low molecular weight compoun...

journal_title：Medical physics

authors： Prost RW

更新日期：2008-10-01 00:00:00

abstract：PURPOSE:X-ray fluorescence computer tomography (XFCT) is a new molecular imaging modality which uses x-ray excitation to stimulate the emission of fluorescent photons in high atomic number contrast agents. Scatter contamination is one of the main challenges in XFCT imaging which limits the molecular sensitivity. When p...

journal_title：Medical physics

authors： Vernekohl D,Tzoumas S,Zhao W,Xing L

更新日期：2018-05-25 00:00:00

abstract：:The availability of digital radiographic imaging on simulators has led to the investigation of a number of new imaging possibilities, including digital linear tomography (tomosynthesis). It has been shown that a single set of projections in this case is sufficient to reconstruct images from multiple planes, including ...

journal_title：Medical physics

authors： Zwicker RD,Atari NA

更新日期：1997-06-01 00:00:00

abstract：PURPOSE:There are several options to consider in the design of a vault that will house a cyclotron for radioisotopes production with regards to the door entrance. Alternatives are a direct-shielded door, a simple maze, or a double-legged maze. In this work, the impact of the neutron and photon doses at the vault entran...

journal_title：Medical physics

authors： Facure A,França WF

更新日期：2010-12-01 00:00:00