Calculating output factors for photon beam radiotherapy using a convolution/superposition method based on a dual source photon beam model.

abstract：PURPOSE:Computational models are widely used during the design and characterization of microwave ablation (MWA) devices, and have been proposed for pretreatment planning. Our objective was to assess three-dimensional (3D) transient temperature and ablation profiles predicted by MWA computational models with temperature...

journal_title：Medical physics

authors： Faridi P,Keselman P,Fallahi H,Prakash P

更新日期：2020-09-01 00:00:00

abstract：:The radiation dose to the lungs from 133Xe in lung air is directly proportional to the time integral of 133Xe concentration; i.e., the cumulated concentration in the lungs. Using kinetic models developed to fit clinical observations, we have studied the effect of retention on cumulated concentration in lung air. The m...

journal_title：Medical physics

authors： Watson EE,Cloutier RJ

更新日期：1977-11-01 00:00:00

abstract：PURPOSE:Compton camera imaging (CCI) systems are currently under investigation for radiotherapy dose reconstruction and verification. The ability of such a system to provide real-time images during dose delivery will be limited by the computational speed of the image reconstruction algorithm. In this work, the authors ...

journal_title：Medical physics

authors： Mundy DW,Herman MG

更新日期：2011-01-01 00:00:00

abstract：:The half-life of two I-125 encapsulated clinical seeds was measured with a Si(Li) semiconductor detector. Two measurements of each seed yielded an average half-life of 59.56 +/- 0.17 days. The results are discussed in terms of the influence of possible I-126 contamination and leakage of I-125 activity through encapsul...

journal_title：Medical physics

authors： Kubo H

更新日期：1983-11-01 00:00:00

abstract：PURPOSE:To evaluate the patient positioning accuracy and reproducibility of two commercially available immobilization systems for Stereotactic Body Radiotherapy (SBRT) treatment. METHODS:Forty one patients with lung (n=21) or liver (n=20) malignancies were assigned to one of the two immobilization devices: Elekta ster...

journal_title：Medical physics

authors： Cao M,Cao N,Cardenes H,Fakiris A,Desrosiers C,Das I

更新日期：2012-06-01 00:00:00

abstract：:The main purpose of this work is to demonstrate a practical means of determining the leaf transmission and scatter characteristics of a multileaf collimator (MLC) pertinent to the commissioning of dynamic intensity modulated radiotherapy, especially for the sweeping window technique. The data are necessary for the con...

journal_title：Medical physics

authors： Arnfield MR,Siebers JV,Kim JO,Wu Q,Keall PJ,Mohan R

更新日期：2000-10-01 00:00:00

abstract：:Model-based deformable organ registration techniques using the finite element method (FEM) have recently been investigated intensively and applied to image-guided adaptive radiotherapy (IGART). These techniques assume that human organs are linearly elastic material, and their mechanical properties are predetermined. U...

journal_title：Medical physics

authors： Chi Y,Liang J,Yan D

更新日期：2006-02-01 00:00:00

abstract：:Calibration of an imported strontium-90 ophthalmic applicator at the U.S. National Bureau of Standards (now the National Institute of Standards and Technology) has disclose a significant discrepancy in dose rate calibration (32%-35%) with that quoted by the manufacturer. The University of Wisconsin has investigated th...

journal_title：Medical physics

authors： Goetsch SJ,Sunderland KS

更新日期：1991-03-01 00:00:00

abstract：:The implementation of an improved model for multiple scattering into the-Voxel Monte Carlo (VMC) algorithm for fast electron dose calculation in radiation therapy is presented. The model takes into account path-length corrections (PLC) and lateral displacement in the individual electron steps. The extraction of the sc...

journal_title：Medical physics

authors： Kawrakow I

更新日期：1997-04-01 00:00:00

abstract：PURPOSE:The goal of this work is to propose a new multichannel method correcting for systematic thickness disturbances and to evaluate its precision in relevant radiation dosimetry applications. METHODS:The eigencolor ratio technique is introduced and theoretically developed to provide a method correcting for thicknes...

journal_title：Medical physics

authors： Bouchard H,Billas I,Subie A,Duane S

更新日期：2021-02-01 00:00:00

abstract：PURPOSE:Real-time tumor position/shape measurement and dynamic beam tracking techniques allow accurate and continuous irradiation to moving tumor, but there can be a delay of several hundred milliseconds between observation and irradiation. A time-variant seasonal autoregressive (TVSAR) model has been proposed for comp...

journal_title：Medical physics

authors： Ichiji K,Homma N,Sakai M,Narita Y,Takai Y,Yoshizawa M

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:To provide an overview of the types of adverse events reported to the US Food and Drug Administration (US FDA) for magnetic resonance (MR) systems over a 10-yr period. METHODS:Two reviewers independently reviewed adverse events reported to FDA for MR systems from 1 January 2008 to 31 December 2017 and manually...

journal_title：Medical physics

authors： Delfino JG,Krainak DM,Flesher SA,Miller DL

更新日期：2019-12-01 00:00:00

abstract：:The feasibility of using film dosimetry data as the input data for patient treatment planning was evaluated. The central-axis depth dose and the off-axis ratios obtained from film measurements in a solid phantom were compared with those of ion-chamber measurements in water. Two techniques were used to generate isodose...

journal_title：Medical physics

authors： Shiu AS,Otte VA,Hogstrom KR

更新日期：1989-11-01 00:00:00

abstract：PURPOSE:To generate hybrid VMAT-IMRT treatment plans by utilizing an IMRT beam-angle-optimality (BAO) search under a commercially available TPS without the aid of custom optimization software or high performance computing. METHODS:The high dose modulation provided by IMRT beams can be exploited to improve the quality ...

journal_title：Medical physics

authors： Schulze D,Ionascu D,Tyagi N

更新日期：2012-06-01 00:00:00

abstract：:In computer simulations of x-ray CT systems one can either use continuous geometrical descriptions for phantoms or a voxelized representation. The voxelized approach allows arbitrary phantoms to be defined without being confined to geometrical shapes. The disadvantage of the voxelized approach is that inherent errors ...

journal_title：Medical physics

authors： Goertzen AL,Beekman FJ,Cherry SR

更新日期：2002-04-01 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：:The dose-rate dependence of commercially available diode detectors was measured under both high instantaneous dose-rate (pulsed) and low dose rate (continuous, Co-60) radiation. The dose-rate dependence was measured in an acrylic miniphantom at a 5-cm depth in a 10 x 10 cm2 collimator setting, by varying source-to-det...

journal_title：Medical physics

authors： Saini AS,Zhu TC

更新日期：2004-04-01 00:00:00

abstract：:The photon energy spectrum emanating from a Leksell Gamma Knife, Model 23004B, was measured between 0.250 and 3.5 MeV with the sources exposed. Measurements were made using a 2x2 inch NaI detector enclosed in a lead-shielded apparatus having a 1/4 inch diameter measurement aperture, which reduced the amount of radiati...

journal_title：Medical physics

authors： Drzymala RE,Sohn JW,Guo C,Sobotka LG,Purdy JA

更新日期：2001-04-01 00:00:00

abstract：PURPOSE:Current on-board imaging systems commonly used by modern linear accelerators (LINACs) have a limited field of view (FOV) for a cone-beam CT (CBCT) scan, which is typically less than 50 cm. Consequently, truncation artifacts often occur for large patients. The goal of this work is to investigate a novel method t...

journal_title：Medical physics

authors： Li T,Li X,Yang Y,Heron DE,Huq MS

更新日期：2010-12-01 00:00:00

abstract：PURPOSE:To introduce a novel laser-based optical-CT scanner for the readout of three-dimensional (3D) radiation dosimeters. METHODS:The scanner employs a diode laser, a cylindrical lens, a motorized linear rail, a rotation stage, and a charge-coupled device camera. The scanner operates in a translate-rotate fashion an...

journal_title：Medical physics

authors： Papadakis AE,Maris TG,Zacharakis G,Papoutsaki V,Varveris C,Ripoll J,Damilakis J

更新日期：2011-02-01 00:00:00

abstract：:In this report we describe an improvement upon the design by Stanton and Lightfoot for a simple photographic null method to determine the kVp of a diagnostic region x-ray source. The new version has two primary advantages over the Ardran and Crooks design in that it is both simpler and less expensive to produce. ...

journal_title：Medical physics

authors： Netto TG,Cameron JR

更新日期：1985-03-01 00:00:00

abstract：PURPOSE:High-spatial-resolution x-ray imaging in the few-ten-keV range is becoming increasingly important in several applications, such as small-animal imaging and phase-contrast imaging. The detector properties critically influence the quality of such imaging. Here the authors present a quantitative comparison of scin...

journal_title：Medical physics

authors： Larsson JC,Lundström U,Hertz HM

更新日期：2016-06-01 00:00:00

abstract：PURPOSE:Real-time sub-millimeter head motion compensation during frameless SRS delivery has the potential to achieve the accuracy of frame-based SRS while being significantly less invasive. Previously, we demonstrated real-time 6D head motion monitoring using an optical camera, however, at the time we were limited to o...

journal_title：Medical physics

authors： Belcher AH,Wiersma RD

更新日期：2012-06-01 00:00:00

abstract：:In prostate seed implants, radioactive seeds are implanted into the prostate through a guiding needle with the help of a template and real-time imaging. The ideal locations of the guiding needles and the relative positions of the seeds in each needle are determined before the implantation under the assumption that the...

journal_title：Medical physics

authors： Nath S,Chen Z,Yue N,Trumpore S,Peschel R

更新日期：2000-05-01 00:00:00

abstract：PURPOSE:Intracavitary accelerated partial breast irradiation (APBI) has become a popular treatment for early stage breast cancer in recent years due to its shortened course of treatment and simplified treatment planning compared to traditional external beam breast conservation therapy. However, the exit dose to the ski...

journal_title：Medical physics

authors： Raffi JA,Davis SD,Hammer CG,Micka JA,Kunugi KA,Musgrove JE,Winston JW Jr,Ricci-Ott TJ,DeWerd LA

更新日期：2010-06-01 00:00:00

abstract：:Lag in fluoroscopic systems introduces a frame-averaging effect that reduces measurements of image noise and incorrectly inflates measurements of the detective quantum efficiency (DQE). A correction can be implemented based on measurements of the temporal modulation transfer function (MTF). We introduce a method of me...

journal_title：Medical physics

authors： Friedman SN,Cunningham IA

更新日期：2008-06-01 00:00:00

abstract：:The resolution has been evaluated for an experimental x-ray image intensifier employing three microchannel plates (MCPs) as the photon absorber and electron multipliers. The line spread function (LSF) was measured and used for determination of the modulation transfer function (MTF). The MTF was found to be independent...

journal_title：Medical physics

authors： Gould RG

更新日期：1978-01-01 00:00:00

abstract：:Myocardial beta adrenergic receptor (beta-AR) concentration can substantially decrease in congestive heart failure and significantly increase in chronic volume overload, such as in severe aortic valve regurgitation. Positron emission tomography (PET) with an appropriate ligand-receptor model can be used for noninvasiv...

journal_title：Medical physics

authors： Salinas C,Muzic RF Jr,Ernsberger P,Saidel GM

更新日期：2007-01-01 00:00:00

abstract：:A photon transport algorithm for fully three-dimensional radiotherapy treatment planning has been developed based on the discrete ordinates (SN) solution of the Boltzmann equation. The algorithm is characterized by orthogonal adaptive meshes, which place additional points where large gradients occur and a procedure to...

journal_title：Medical physics

authors： Yuan J,Jette D,Chen W

更新日期：2008-09-01 00:00:00

abstract：PURPOSE:Body composition is known to be associated with many diseases including diabetes, cancers, and cardiovascular diseases. In this paper, we developed a fully automatic body tissue decomposition procedure to segment three major compartments that are related to body composition analysis - subcutaneous adipose tissu...

journal_title：Medical physics

authors： Fu Y,Ippolito JE,Ludwig DR,Nizamuddin R,Li HH,Yang D

更新日期：2020-11-01 00:00:00