On the capabilities of conventional x-ray tubes to deliver ultra-high (FLASH) dose rates.

abstract：PURPOSE:High-dose-rate brachytherapy (HDR-BT) is a treatment option for malignant skin diseases compared to external beam radiation therapy, HDR-BT provides improved target coverage, better organ sparing, and has comparable treatment times. This is especially true for large clinical targets with complex topologies. To ...

journal_title：Medical physics

authors： Guthier CV,Devlin PM,Harris TC,O'Farrell DA,Cormack RA,Buzurovic I

更新日期：2020-03-01 00:00:00

abstract：:An analytic representation proposed for the relative intensity distribution of the extra-focal source in a two-component x-ray source model serves as the basis for calculation. From this representation, a closed-form expression for head scatter factors defined on the central beam axis is derived by integrating over th...

journal_title：Medical physics

authors： Yu MK,Sloboda R

更新日期：1995-12-01 00:00:00

abstract：:The purpose of this paper is to determine the correlation between dose-volume histogram (DVH) and dose wall-histogram (DWH) in the evaluation of rectal complications for prostate cancer patients treated with three-dimensional conformal radiotherapy (3D-CRT). A retrospective analysis of DVHs and DWHs of a subset of 25 ...

journal_title：Medical physics

authors： García-Vicente F,Zapatero A,Floriano A,Cruz-Conde A,Perez L,Marín A,Mínguez C,Torres JJ

更新日期：2005-08-01 00:00:00

abstract：:To improve beam penetration into a head allowing the treatment of deeper seated tumors, two neutron collimators were built sequentially and tested for use in the clinical boron neutron capture therapy (BNCT) program at the epithermal neutron irradiation facility of the Brookhaven Medical Research Reactor. The collimat...

journal_title：Medical physics

authors： Liu HB,Greenberg DD,Capala J,Wheeler FJ

更新日期：1996-12-01 00:00:00

abstract：:An important aspect of dual-energy (DE) x-ray image decomposition is the incorporation of noise reduction techniques to mitigate the amplification of quantum noise. This article extends cascaded systems analysis of imaging performance to DE imaging systems incorporating linear noise reduction algorithms. A general ana...

journal_title：Medical physics

authors： Richard S,Siewerdsen JH

更新日期：2008-02-01 00:00:00

abstract：PURPOSE:When an intensity-modulated radiation beam is delivered to a moving target, the interplay effect between dynamic beam delivery and the target motion due to miss-synchronization can cause unpredictable dose delivery. The portal dose image in electronic portal imaging device (EPID) represents radiation attenuated...

journal_title：Medical physics

authors： Yeo IJ,Jung JW,Yi BY,Kim JO

更新日期：2013-05-01 00:00:00

abstract：PURPOSE:Current treatment planning for 90 Y radioembolization estimates lung mean dose (LMD) by measuring the lung shunt fraction (LSF) from 99m Tc-macroaggregated albumin (MAA) planar imaging and assuming a 1-kg lung mass. This methodology, however, overestimates LSF and LMD and could therefore unnecessarily limit the...

journal_title：Medical physics

authors： Lopez B,Mahvash A,Lam MGEH,Kappadath SC

更新日期：2019-09-01 00:00:00

abstract：PURPOSE:To add mathematical rigor to the merging phase of the recently published two-stage VMAT optimization method called VMERGE. Using an exact merging method, we are able to better characterize the tradeoff between delivery efficiency and dose quality. METHODS:VMERGE begins with an IMRT plan that uses 180 equi-spac...

journal_title：Medical physics

authors： Salari E,Craft D

更新日期：2012-06-01 00:00:00

abstract：:Optical-resolution photoacoustic microscopy (OR-PAM) has been validated as a valuable tool for label-free volumetric microvascular imaging. More importantly, the advantages of noninvasiveness and measurement consistency suggest the use of OR-PAM for chronic imaging of intact microcirculation. Here, such chronic imagin...

journal_title：Medical physics

authors： Hu S,Maslov K,Wang LV

更新日期：2009-06-01 00:00:00

abstract：:The most favorable treatment for moving body anatomy should aim at utilizing organ motion to minimize the dose to sensitive structures without compromising the dose delivered to the target. The solution of the problem of appropriate intensity redistribution over different phases of body motion is achievable in dynamic...

journal_title：Medical physics

authors： Papiez L,McMahon R,Timmerman R

更新日期：2007-12-01 00:00:00

abstract：:Depth dose distributions for a d(14)Be neutron beam, measured separately for total and gamma absorbed dose, are presented for nine tissue substitutes and for two field sizes. These data are used to examine methods to transform depth dose curves from one material to another. Best results are found when the local depths...

journal_title：Medical physics

authors： Hensley FW,Rassow J,Temme A

更新日期：1985-05-01 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:The purpose of this study is to evaluate the feasibility of kilovoltage cone-beam CT (CBCT) images that are obtained with the Varian On-Board Imager in dose calculation at each radiation therapy. METHODS:CBCT images are commonly degraded by scattered radiations originating in the patient's body, and so the CT ...

journal_title：Medical physics

authors： Usui K,Ogawa K,Kunieda E

更新日期：2012-06-01 00:00:00

abstract：PURPOSE:To develop a computer-driven and thus less user-dependent method, allowing for a simple and straightforward generation of a Monte Carlo (MC) beam model of a scanned proton and carbon ion beam delivery system. METHODS:In a first step, experimental measurements were performed for proton and carbon ion energies i...

journal_title：Medical physics

authors： Fuchs H,Elia A,Resch AF,Kuess P,Lühr A,Vidal M,Grevillot L,Georg D

更新日期：2020-12-07 00:00:00

abstract：:The surface radio frequency (rf) power absorption in human head and torso nuclear magnetic resonance (NMR) imaging experiments is estimated. The results are expressed as a function of the NMR frequency, the rf pulse length, and the pulse duty cycle, which are varied over six orders of magnitude for general applicabili...

journal_title：Medical physics

authors： Bottomley PA,Edelstein WA

更新日期：1981-07-01 00:00:00

abstract：PURPOSE:Intensity-Modulated Radiation Therapy (IMRT), including its variations (including IMRT, Volumetric Arc Therapy (VMAT), and Tomotherapy), is a widely used and critically important technology for cancer treatment. It is a knowledge-intensive technology due not only to its own technical complexity, but also to the...

journal_title：Medical physics

authors： Ge Y,Wu QJ

更新日期：2019-06-01 00:00:00

abstract：PURPOSE:This paper provides a comparison between a fast, commercial, in-patient Monte Carlo dose calculation algorithm (GPUMCD) and geant4. It also evaluates the dosimetric impact of the application of an external 1.5 T magnetic field. METHODS:A stand-alone version of the Elekta™ GPUMCD algorithm, to be used within th...

journal_title：Medical physics

authors： Ahmad SB,Sarfehnia A,Paudel MR,Kim A,Hissoiny S,Sahgal A,Keller B

更新日期：2016-02-01 00:00:00

abstract：:A detailed Monte Carlo study of the PTW-diamond solid state detector response in megavoltage photon beams (60Co gamma rays to 25 MV x rays) has been performed with the EGS4 Monte Carlo Code. The sensitive volume of the diamond detector is a disk of diameter 4.4 mm and thickness 0.40 mm. The phantom material was water ...

journal_title：Medical physics

authors： Mobit PN,Sandison GA

更新日期：1999-11-01 00:00:00

abstract：PURPOSE:Liver segmentation is an important prerequisite for the assessment of liver cancer treatment options like tumor resection, image-guided radiation therapy (IGRT), radiofrequency ablation, etc. The purpose of this work was to evaluate a new approach for liver segmentation. METHODS:A graph cuts segmentation metho...

journal_title：Medical physics

authors： Beichel R,Bornik A,Bauer C,Sorantin E

更新日期：2012-03-01 00:00:00

abstract：:MR acoustic radiation force (ARF) imaging was developed for measuring tiSsue elastic properties using focused ultrasound to deliver a localized tissue motion. In this study, an imaging ultrasound transducer was mounted on the focused ultrasound transducer and ultrasound motion tracking was performed simultaneously to ...

journal_title：Medical physics

authors： Huang Y,Curiel L,Kukic A,Plewes DB,Chopra R,Hynynen K

更新日期：2009-06-01 00:00:00

abstract：PURPOSE:Accurate detection of pulmonary nodules remains a technical challenge in computer-aided diagnosis systems because some nodules may adhere to the blood vessels or the lung wall, which have low contrast compared to the surrounding tissues. In this paper, the analysis of typical shape features of candidate nodules...

journal_title：Medical physics

authors： Wang B,Tian X,Wang Q,Yang Y,Xie H,Zhang S,Gu L

更新日期：2015-03-01 00:00:00

abstract：:The objective of this work was to create a comprehensive online tool to evaluate and review the performance of quality assurance measurements that assess beam output and profile constancy as soon as they are acquired using statistical process control. As part of routine quality assurance: output, flatness and symmetry...

journal_title：Medical physics

authors： Chmielewski R,Abbas A,Yeung I

更新日期：2012-07-01 00:00:00

abstract：PURPOSE:To develop a novel system for patient-specific combined optimization of couch, collimator, and gantry angles for use in volumetric modulated arc therapy (VMAT) treatment planning. The system was designed to produce highly compact dose distributions by extensively sampling the 4π space. Automated fixed couch tra...

journal_title：Medical physics

authors： MacDonald RL,Syme A,Little B,Ward L,Thomas CG

更新日期：2020-02-01 00:00:00

abstract：PURPOSE:Radiosensitizer enhanced radiotherapy provides the possibility of improved treatment outcomes by preferentially increasing the effectiveness of radiation within the tumor. Proton therapy offers improved sparing of tissue distal of the tumor along the beam path and reduced integral dose compared to conventional ...

journal_title：Medical physics

authors： Peukert D,Kempson I,Douglass M,Bezak E

更新日期：2020-02-01 00:00:00

abstract：:Recent work has shown that there is significant uncertainty in measuring build-up doses in mega-voltage photon beams especially at high energies. In this present investigation we used a phantom-embedded extrapolation chamber (PEEC) made of Solid Water to validate Monte Carlo (MC)-calculated doses in the dose build-up ...

journal_title：Medical physics

authors： Abdel-Rahman W,Seuntjens JP,Verhaegen F,Deblois F,Podgorsak EB

更新日期：2005-01-01 00:00:00

abstract：PURPOSE:Couch and MLC tracking are two promising methods for real-time motion compensation during radiation therapy. So far, couch and MLC tracking experiments have mainly been performed by different research groups, and no direct comparison of couch and MLC tracking of volumetric modulated arc therapy (VMAT) plans has...

journal_title：Medical physics

authors： Hansen R,Ravkilde T,Worm ES,Toftegaard J,Grau C,Macek K,Poulsen PR

更新日期：2016-05-01 00:00:00

abstract：PURPOSE/OBJECTIVE:Couch and MLC tracking are two novel techniques to mitigate intrafractional tumor motion on a conventional linear accelerator, but both techniques still have residual dosimetric errors. Here, we first propose and experimentally validate a software tool to simulate couch and MLC tracking, and then use ...

journal_title：Medical physics

authors： Toftegaard J,Hansen R,Ravkilde T,Macek K,Poulsen PR

更新日期：2017-03-01 00:00:00

abstract：:Diode sensitivity variations with temperature (SVWT) have been reported to vary from small negative values up to 0.6% per degrees C. Thus it is possible for diode calibration factors established at room temperature (approximately 20 degrees C) to yield errors in the range of -1% to +9% when diodes are placed on a pati...

journal_title：Medical physics

authors： Welsh KT,Reinstein LE

更新日期：2001-05-01 00:00:00

abstract：:Variations in the atomic composition, and mass and electron densities of polystyrene and polymethylmethacrylate (PMM) plastics were assessed from experimentally determined mass attenuation coefficients for 125I and 137Cs gamma rays. The means and standard deviations in the mass densities of 16 samples of PMM and 10 sa...

journal_title：Medical physics

authors： Schulz RJ,Nath R

更新日期：1979-03-01 00:00:00

abstract：PURPOSE:Atherosclerosis of peripheral cerebral arteries can lead to stroke either by stenosis formation or plaque rupture. This pathology is initiated by the alteration of arterial wall mechanical properties shown to be assessable by ultrasound elastography. Recently, noninvasive vascular elastography (NIVE) was introd...

journal_title：Medical physics

authors： Mercure E,Deprez JF,Fromageau J,Basset O,Soulez G,Cloutier G,Maurice RL

更新日期：2011-02-01 00:00:00