Detecting electron beam energy shifts with a commercially available energy monitor.

abstract：:Intrafraction organ motion can limit the advantage of highly conformal dose techniques such as intensity modulated radiation therapy (IMRT) due to target position uncertainty. To ensure high accuracy in beam targeting, real-time knowledge of the target location is highly desired throughout the beam delivery process. T...

journal_title：Medical physics

authors： Mao W,Wiersma RD,Xing L

更新日期：2008-05-01 00:00:00

abstract：:The dose distributions in the bifurcated vessels treated with intravascular brachytherapyline sources are complicated and depend on the bifurcation geometry consisting of a main and a branch vessel at different angles. To investigate the dosimetric effects at the bifurcation, calculations were performed on branching v...

journal_title：Medical physics

authors： Yue N,Roberts KB,Pfau SE,Nath R

更新日期：2003-07-01 00:00:00

abstract：PURPOSE:The purpose of this study was to describe and evaluate methods for calculating a megavoltage computed tomography (MVCT)-derived MR hardware attenuation map (μ-map) and dual-energy CT (DECT) for 511 keV photons. METHODS:Phantom measurements were acquired on a whole-body hybrid PET/MRI system, using a four-chann...

journal_title：Medical physics

authors： Patrick JC,Terry Thompson R,So A,Butler J,Faul D,Stodilka RZ,Yartsev S,Prato FS,Gaede S

更新日期：2017-09-01 00:00:00

abstract：:Fluoroscopy is a low dose imaging technique. As such, a very sensitive detector is required to create images of good quality. Present day flat panel active matrix read out systems introduce an amount of noise that inhibits present direct and indirect methods from producing optimal quality images at fluoroscopic exposu...

journal_title：Medical physics

authors： Hunt DC,Kirby SS,Rowlands JA

更新日期：2002-11-01 00:00:00

abstract：:Many papers discussed the I value for water given by the ICRU, concluding that a value of about 80 +/- 2 eV instead of 67.2 eV would reproduce measured ion depth-dose curves. A change in the I value for water would have an effect on the stopping power and, hence, on the water-to-air stopping power ratio, which is impo...

journal_title：Medical physics

authors： Henkner K,Bassler N,Sobolevsky N,Jäkel O

更新日期：2009-04-01 00:00:00

abstract：PURPOSE:To validate a delivery quality assurance (DQA) protocol for tomotherapy based on the measurement of the leaf open times (LOTs). In addition, to show the correlation between the mean relative LOT discrepancy and the dose deviation in the planning target volume (PTV). MATERIALS AND METHODS:We used a LOT measurem...

journal_title：Medical physics

authors： Schopfer M,Bochud FO,Bourhis J,Moeckli R

更新日期：2020-09-01 00:00:00

abstract：PURPOSE:Quantitative SPECT imaging is limited by many factors, including penetration of high energy photons through the collimator. Even small peaks of high energy yield extensive contamination in the photopeak energy window. Rotating slat collimators typically offer a 40- to 50-fold increase in geometric detection eff...

journal_title：Medical physics

authors： Van Holen R,Staelens S,Vandenberghe S

更新日期：2009-09-01 00:00:00

abstract：:Cone beam transmission CT (CB-CT) improves SPECT imaging by providing high-quality attenuation maps for attenuation compensation and for correlated SPECT and CT imaging. The present work measures the detection nonuniformity for CB-CT implemented with a gamma camera, and applies nonuniformity corrections to make CB-CT ...

journal_title：Medical physics

authors： Manglos SH,Capone RB,Bassano DA

更新日期：1992-03-01 00:00:00

abstract：PURPOSE:Signal encoding in magnetic particle imaging (MPI) is achieved by moving a field-free point (FFP) through the region of interest. One way to increase the sensitivity of the method is to scan the region of interest with a field-free line (FFL) instead of the FFP. Recently, the first feasible FFL coil setup was i...

journal_title：Medical physics

authors： Knopp T,Erbe M,Biederer S,Sattel TF,Buzug TM

更新日期：2010-07-01 00:00:00

abstract：PURPOSE:Computed tomography (CT) is one of the most used imaging modalities for imaging both symptomatic and asymptomatic patients. However, because of the high demand for lower radiation dose during CT scans, the reconstructed image can suffer from noise and artifacts due to the trade-off between the image quality and...

journal_title：Medical physics

authors： Kim K,El Fakhri G,Li Q

更新日期：2017-10-01 00:00:00

abstract：PURPOSE:We studied the sensitivity of a novel transmission fiber scintillator array designed and built for in line treatment verification. The purpose of this project is to assess the capability of the fiber detector array technology to detect treatment errors in real time without false positives to enhance patient saf...

journal_title：Medical physics

authors： Izaguirre EW,Price SG,Smajlovic S,Yaddanapudi S,Wooten H,Mutic S

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:This study aims to measure the surface dose on an anthropomorphic phantom for intensity-modulated radiation therapy (IMRT) plans treated in a 1.5 T magnetic resonance (MR)-Linac. Previous studies have used Monte Carlo programs to simulate surface dose and have recognized high surface dose as a potential limitin...

journal_title：Medical physics

authors： Lim-Reinders S,Keller BM,Sahgal A,Chugh B,Kim A

更新日期：2020-07-01 00:00:00

abstract：PURPOSE:The combination of nonhuman primates (NHPs) with the state-of-the-art molecular imaging technologies allows for within-subject longitudinal research aiming at gaining new insights into human normal and disease conditions and provides an ideal foundation for future translational studies of new diagnostic tools, ...

journal_title：Medical physics

authors： Xie T,Chen X,Zaidi H

更新日期：2020-09-01 00:00:00

abstract：PURPOSE:Photon counting arrays (PCAs), capable of measuring the spectral information of individual x-ray photons and recording that information digitally, provide a number of advantages compared to conventional, energy-integrating active matrix flat-panel imagers - such as reducing the undesirable effects of electronic...

journal_title：Medical physics

authors： Liang AK,Koniczek M,Antonuk LE,El-Mohri Y,Zhao Q

更新日期：2018-10-01 00:00:00

abstract：PURPOSE:Currently, in clinical practice of intensity-modulated proton therapy (IMPT), the influence of the minimum monitor unit (MU) constraint is taken into account through postprocessing after the optimization is completed. This may degrade the plan quality and plan robustness. This study aims to mitigate the impact ...

journal_title：Medical physics

authors： Shan J,An Y,Bues M,Schild SE,Liu W

更新日期：2018-01-01 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

abstract：:A comprehensive performance testing program is an essential ingredient of high-quality single-photon emission computed tomography (SPECT). Many of the procedures previously published are complicated, time consuming, or require a special testing environment. This Task Group developed a protocol for evaluating SPECT ima...

journal_title：Medical physics

authors： Graham LS,Fahey FH,Madsen MT,van Aswegen A,Yester MV

更新日期：1995-04-01 00:00:00

abstract：PURPOSE:Small animal immobilization devices facilitate positioning of animals for reproducible imaging and accurate focal radiation therapy. In this study, the authors demonstrate the use of three-dimensional (3D) printing technology to fabricate a custom-designed mouse head restraint. The authors evaluate the accuracy...

journal_title：Medical physics

authors： Zarghami N,Jensen MD,Talluri S,Foster PJ,Chambers AF,Dick FA,Wong E

更新日期：2015-11-01 00:00:00

abstract：PURPOSE:To present EBT2 film verification of treatment planning with the eXtend System, a relocatable frame system for multiple-fraction or serial multiple-session radiosurgery. METHODS:A human head shaped phantom simulated the verification process for fractionated Gamma Knife (GK) treatment. Phantom preparation for e...

journal_title：Medical physics

authors： Gopishankar N,Bisht RK

更新日期：2012-06-01 00:00:00

abstract：:The goal is to perform geometric studies on cone-beam CT scanning along a three-dimensional (3D) spiral of variable radius. First, the background for variable radius spiral cone-beam scanning is given in the context of electron-beam CT/micro-CT. Then, necessary and sufficient conditions are proved for existence and un...

journal_title：Medical physics

authors： Yea Y,Zhu J,Wang G

更新日期：2004-06-01 00:00:00

abstract：PURPOSE:To demonstrate the ultra-high resolution capability of a small field-of-view (FOV) solid state x-ray imaging detector based on an EMCCD sensor. METHODS:A micro-solid state x-ray image intensifier (micro-SSXII) was developed to serve as an ultra-high resolution region-of-interest (ROI) imaging detector. It is b...

journal_title：Medical physics

authors： Singh V,Loughran B,Jain A,Sharma P,Bednarek D,Rudin S

更新日期：2012-06-01 00:00:00

abstract：:Several updated Monte Carlo (MC) codes are available to perform calculations of voxel S values for radionuclide targeted therapy. The aim of this work is to analyze the differences in the calculations obtained by different MC codes and their impact on absorbed dose evaluations performed by voxel dosimetry. Voxel S val...

journal_title：Medical physics

authors： Pacilio M,Lanconelli N,Lo MS,Betti M,Montani L,Torres AL,Coca PM

更新日期：2009-05-01 00:00:00

abstract：:Neutron cross sections for nonelastic and elastic reactions on a range of elements have been evaluated for incident energies up to 150 MeV. These cross sections agree well with experimental cross section data for charged-particle production as well as neutron and photon production. Therefore they can be used to determ...

journal_title：Medical physics

authors： Chadwick MB,Barschall HH,Caswell RS,DeLuca PM,Hale GM,Jones DT,MacFarlane RE,Meulders JP,Schuhmacher H,Schrewe UJ,Wambersie A,Young PG

更新日期：1999-06-01 00:00:00

abstract：:Electron beam dosimetry at low monitor unit (MU) settings is important for dosimetric applications. Dose linearity, beam flatness, and beam energies were studied at low MU settings with various dose rates for different types of linear accelerators. It is observed that for the scattering foil units, the dose/MU is a sm...

journal_title：Medical physics

authors： Das IJ,Harrington JC,Akber SF,Tomer AF,Murray JC,Cheng CW

更新日期：1994-06-01 00:00:00

abstract：PURPOSE:The aim of this work is to search for new metrics that could give more reliable acceptance/rejection criteria on the IMRT verification process and to offer solutions to the discrepancies found among different conventional metrics. Therefore, besides conventional metrics, new ones are proposed and evaluated with...

journal_title：Medical physics

authors： Garcia-Romero A,Hernandez-Vitoria A,Millan-Cebrian E,Alba-Escorihuela V,Serrano-Zabaleta S,Ortega-Pardina P

更新日期：2016-11-01 00:00:00

abstract：PURPOSE:The fundamental nature of positron emission tomography (PET), as an event detection system, provides some flexibility for data handling, including retrospective data manipulation. The reorganization of acquisition data allows the emulation of new scans arising from identical radiotracer spatial distributions, b...

journal_title：Medical physics

authors： Schaefferkoetter J,Nai YH,Reilhac A,Townsend DW,Eriksson L,Conti M

更新日期：2019-06-01 00:00:00

abstract：:The 1983 AAPM protocol for the determination of absorbed dose from high-energy photon and electron beams recommends using Pion (the reciprocal of collection efficiency), as determined by the two-voltage technique, to correct for recombination losses in ionization chambers. Methods and data for the determination of ion...

journal_title：Medical physics

authors： Weinhous MS,Meli JA

更新日期：1984-11-01 00:00:00

abstract：PURPOSE:Deformable image registration (DIR) is often validated based on a distance-to-agreement (DTA) criterion of automatically propagated anatomical landmarks that were manually identified. Due to human observer variability, however, the performance of the registration method is diluted. The purpose of this study was...

journal_title：Medical physics

authors： Mencarelli A,van Beek S,van Kranen S,Rasch C,van Herk M,Sonke JJ

更新日期：2012-11-01 00:00:00

abstract：:Gafchromic XRCT, radiochromic film is assessed over a broad energy range, from kilovoltage to megavoltage x rays for variations in reflected optical density to dose response. A large energy dependence was found with reflected optical density output for the same delivered dose varying from 7.8 +/- 0.35 at 25.5 keV (50 ...

journal_title：Medical physics

authors： Butson MJ,Cheung T,Yu PK

更新日期：2006-08-01 00:00:00

abstract：PURPOSE:Accurate calculation of proton stopping power ratio (SPR) relative to water is crucial to proton therapy treatment planning, since SPR affects prediction of beam range. Current standard practice derives SPR using a single CT scan. Recent studies showed that dual-energy CT (DECT) offers advantages to accurately ...

journal_title：Medical physics

authors： Shen C,Li B,Chen L,Yang M,Lou Y,Jia X

更新日期：2018-04-01 00:00:00