Abstract:
PURPOSE:To commission and benchmark a vendor-supplied (Varian Medical Systems) Monte Carlo phase-space data for the 6 MV flattening filter free (FFF) energy mode on a TrueBeam linear accelerator for the purpose of quality assurance of clinical volumetric modulated arc therapy (VMAT) treatment plans. A method for rendering the phase-space data compatible with BEAMnrc/DOSXYZnrc simulation software package is presented. METHODS:Monte Carlo (MC) simulations were performed to benchmark the TrueBeam 6 MV FFF phase space data that have been released by the Varian MC Research team. The simulations to benchmark the phase space data were done in three steps. First, the original phase space which was created on a cylindrical surface was converted into a format that was compatible with BEAMnrc. Second, BEAMnrc was used to create field size specific phase spaces located underneath the jaws. Third, doses were calculated with DOSXYZnrc in a water phantom for fields ranging from 1 × 1 to 40 × 40 cm(2). Calculated percent depth doses (PDD), transverse profiles, and output factors were compared with measurements for all the fields simulated. After completing the benchmarking study, three stereotactic body radiotherapy (SBRT) VMAT plans created with the Eclipse treatment planning system (TPS) were calculated with Monte Carlo. Ion chamber and film measurements were also performed on these plans. 3D gamma analysis was used to compare Monte Carlo calculation with TPS calculations and with film measurement. RESULTS:For the benchmarking study, MC calculated and measured values agreed within 1% and 1.5% for PDDs and in-field transverse profiles, respectively, for field sizes >1 × 1 cm(2). Agreements in the 80%-20% penumbra widths were better than 2 mm for all the fields that were compared. With the exception of the 1 × 1 cm(2) field, the agreement between measured and calculated output factors was within 1%. It is of note that excellent agreement in output factors for all field sizes including highly asymmetric fields was achieved without accounting for backscatter into the beam monitor chamber. For the SBRT VMAT plans, the agreement between Monte Carlo and ion chamber point dose measurements was within 1%. Excellent agreement between Monte Carlo, treatment planning system and Gafchromic film dose distribution was observed with over 99% of the points in the high dose volume passing the 3%, 3 mm gamma test. CONCLUSIONS:The authors have presented a method for making the Varian IAEA compliant 6 MV FFF phase space file of the TrueBeam linac compatible with BEAMnrc/DOSXYZnrc. After benchmarking the modified phase space against measurement, they have demonstrated its potential for use in MC based quality assurance of complex delivery techniques.
journal_name
Med Physjournal_title
Medical physicsauthors
Gete E,Duzenli C,Milette MP,Mestrovic A,Hyde D,Bergman AM,Teke Tdoi
10.1118/1.4773883subject
Has Abstractpub_date
2013-02-01 00:00:00pages
021707issue
2eissn
0094-2405issn
2473-4209journal_volume
40pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract::An indirect flat-panel imager (FPI) with avalanche gain is being investigated for low-dose x-ray imaging. It is made by optically coupling a structured x-ray scintillator CsI(Tl) to an amorphous selenium (a-Se) avalanche photoconductor called HARP (high-gain avalanche rushing photoconductor). The final electronic imag...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2008428
更新日期:2005-09-01 00:00:00
abstract:PURPOSE:The variable resolution x-ray (VRX) CT scanner provides substantial improvement in the spatial resolution by matching the scanner's field of view (FOV) to the size of the object being imaged. Intercell x-ray cross-talk is one of the most important factors limiting the spatial resolution of the VRX detector. In ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3555035
更新日期:2011-03-01 00:00:00
abstract::Electron spectral reconstruction of medical accelerators from measured depth doses is a practical method for providing the input initial phase space distribution at the patient surface that is required by Monte Carlo treatment planning systems. The posed inverse problem of spectral reconstruction is ill conditioned an...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2161404
更新日期:2006-02-01 00:00:00
abstract:PURPOSE:Using a new linear accelerator with high dose rate (800 MU/min), fast MLC motions (5.0 cm/s), fast gantry rotation (15 s/rotation), and 1 cm wide MLCs, we aimed to quantify the effects of complexity, arc number, and fractionation on interplay for breast and lung treatments under target motion. METHODS:To study...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12899
更新日期:2018-06-01 00:00:00
abstract::Multislice helical computed tomography (CT) is a promising noninvasive technique for coronary artery imaging. Various factors can cause inconsistencies in cardiac CT data, which can result in degraded image quality. These inconsistencies may be the result of the patient physiology (e.g., heart rate variations), the na...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2163247
更新日期:2006-02-01 00:00:00
abstract:PURPOSE:The dosimetric advantage of particle therapy comes with a much higher infrastructure investment and operation costs. Increasing patient throughput is a key factor to manage operation costs. We investigate the impact of variable beam spot sizes on treatment time and discuss the tradeoffs involved. METHODS:The f...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735699
更新日期:2012-06-01 00:00:00
abstract::Ultrasound has been the greatest imaging modality worldwide for many years by equipment purchase value and by number of machines and examinations. It is becoming increasingly the front end imaging modality; serving often as an extension of the physician's fingers. We believe that at the other extreme, high-end systems...
journal_title:Medical physics
pub_type: 杂志文章,评审
doi:10.1118/1.2992048
更新日期:2009-02-01 00:00:00
abstract:PURPOSE:Colon cancer is a major public health problem due to its high disease rate and death toll worldwide. The use of FTIR microscopy in the field of cancer diagnosis has become attractive over the past 20 years. In the present study, the authors investigated the potential of FTIR microscopy to define spectral change...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3298013
更新日期:2010-03-01 00:00:00
abstract::The noise power spectrum (NPS) is a useful metric for understanding the noise content in images. To examine some unique properties of the NPS of fan beam CT, the authors derived an analytical expression for the NPS of fan beam CT and validated it with computer simulations. The nonstationary noise behavior of fan beam ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3378673
更新日期:2010-05-01 00:00:00
abstract::A small, lightweight, single-focusing magnetic spectrometer was designed, assembled, and tested for analysis of electron beams from radiotherapy electron linacs. The objective was to develop a low cost, simple device that could be easily replicated in other medical centers, and to demonstrate the practicality of indiv...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597271
更新日期:1994-11-01 00:00:00
abstract::The ability of Leksell GammaPlan to perform stereotactic space localizations with image sets where there is misalignment of the patient's head (stereotactic frame and fiducial apparatus) relative to the computed tomography (CT) scanner coordinate system was studied. Misalignment is sometimes necessary for patient comf...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2179751
更新日期:2006-04-01 00:00:00
abstract:PURPOSE:New preclinical image-guided irradiators and treatment planning systems represent a huge progress in radiobiology. Nevertheless, quality control of preclinical treatments is not as advanced as in clinical radiotherapy and in vivo dosimetry is less developed. In this study, we evaluate the use of a scintillating...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13903
更新日期:2020-01-01 00:00:00
abstract::Consensus has been developing over the past few decades on a number of measurements required for the laboratory assessment of medical imaging modalities. Nevertheless, understanding of the connection between these measurements and human observer performance in a broad range of tasks remains far from complete. Focusing...
journal_title:Medical physics
pub_type: 杂志文章,评审
doi:10.1118/1.597511
更新日期:1995-07-01 00:00:00
abstract::The purpose of this work is to calculate the dose perturbations due to the presence of iodine contrast media in catheter-based intravascular brachytherapy (IVBT). The EGSnrc Monte Carlo system was used to perform the calculation for the two most commonly used beta and gamma sources (90Sr and 192Ir as well as for a var...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1367279
更新日期:2001-05-01 00:00:00
abstract:PURPOSE:Modern clinical accelerators are capable of producing ion beams from protons up to neon. This work compares the depth dose distribution and corresponding dose averaged linear energy transfer (LET) distribution, which is related to the biological effectiveness, for different ion beams (¹H, ⁴He, ⁶Li, ⁸Be, ¹⁰B, ¹²...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3662911
更新日期:2011-12-01 00:00:00
abstract::Accurate targeting is important in intensity-modulated radiation therapy (IMRT). The positional uncertainties of structures with respect to the external beams arise in part from random organ motion and patient setup errors. While it is important to improve immobilization and reduce the influence of organ motion, the r...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.599023
更新日期:2000-07-01 00:00:00
abstract::A statistical analysis has been made of ionometrically measured parameters related to the central-axis output, the beam symmetry, the beam flatness, and the depth dose for the 6-MV x-ray beam from the Therac-6 linear accelerator. The means and coefficients of variation of the measurements are determined on a monthly b...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595642
更新日期:1984-09-01 00:00:00
abstract:PURPOSE:Deformable registration generally relies on the assumption that the sought spatial transformation is smooth. Yet, breathing motion involves sliding of the lung with respect to the chest wall, causing a discontinuity in the motion field, and the smoothness assumption can lead to poor matching accuracy. In respon...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3679009
更新日期:2012-02-01 00:00:00
abstract::A computerized scheme is being developed for the detection of masses in digital mammograms. Based on the deviation from the normal architectural symmetry of the right and left breasts, a bilateral subtraction technique is used to enhance the conspicuity of possible masses. The scheme employs two pairs of conventional ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596610
更新日期:1991-09-01 00:00:00
abstract:PURPOSE:Though failure mode and effects analysis (FMEA) is becoming more widely adopted for risk assessment in radiation therapy, to our knowledge, its output has never been validated against data on errors that actually occur. The objective of this study was to perform FMEA of a stereotactic body radiation therapy (SB...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4919440
更新日期:2015-06-01 00:00:00
abstract:PURPOSE:Metastatic melanoma lesions experienced marked regression after systemic targeted alpha therapy in a phase 1 clinical trial. This unexpected response was ascribed to tumor antivascular alpha therapy (TAVAT), in which effective tumor regression is achieved by killing endothelial cells (ECs) in tumor capillaries ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3681010
更新日期:2012-03-01 00:00:00
abstract::Setting up and maintaining video display monitors properly will help to reduce display variation and improve overall presentation of the radiological image. Display monitor gray-scale characteristics were examined using the SMPTE test pattern. This test pattern may be used as a standard for adjusting brightness and co...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596846
更新日期:1992-05-01 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
pub_type: 杂志文章
doi:10.1002/mp.12407
更新日期:2017-09-01 00:00:00
abstract:PURPOSE:When designing a collimation system for pencil beam spot scanning proton therapy, a decision must be made whether or not to rotate, or focus, the collimator to match beamlet deflection as a function of off-axis distance. If the collimator is not focused, the beamlet shape and fluence will vary as a function of ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14139
更新日期:2020-07-01 00:00:00
abstract::The accuracy of interpolation or averaging procedures for obtaining the calibration coefficient N(K) for 192Ir high-dose-rate brachytherapy sources has been investigated using the EGSnrc Monte Carlo simulation system. It is shown that the widely used two-point averaging procedure of Goetsch et al. [Med. Phys. 18, 462 ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2239198
更新日期:2006-09-01 00:00:00
abstract::In order to investigate the relationship between diagnostic accuracy and radiographic image quality, we have developed a dual-film cassette which produces two radiographs simultaneously with a single exposure. One of these radiographs is of standard quality; the second is of lower quality because of degraded spatial r...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595546
更新日期:1984-09-01 00:00:00
abstract:PURPOSE:To describe Acuros® CTS, a new software tool for rapidly and accurately estimating scatter in x-ray projection images by deterministically solving the linear Boltzmann transport equation (LBTE). METHODS:The LBTE describes the behavior of particles as they interact with an object across spatial, energy, and dir...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12850
更新日期:2018-05-01 00:00:00
abstract:PURPOSE:To describe and mathematically validate the superiorization methodology, which is a recently developed heuristic approach to optimization, and to discuss its applicability to medical physics problem formulations that specify the desired solution (of physically given or otherwise obtained constraints) by an opti...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4745566
更新日期:2012-09-01 00:00:00
abstract::Proton NMR spectroscopy was applied to quantitate the measurement of total body water/fat distributions in vivo. A special MR protocol was developed to excite a thick slab of tissue and display the magnitude NMR spectrum of the collected response signal. Very short echo time TE (8 ms) and long repetition time TR (4000...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596935
更新日期:1992-01-01 00:00:00
abstract::A computed tomography (CT) based system that compensates for patient surface contour and internal tissue inhomogeneity was implemented in our clinic. The compensators are fabricated with a mixture of tin granules and bee's wax. The tin/wax mixture was optimized for tin granule size and tin granule to wax ratio. The na...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597303
更新日期:1994-03-01 00:00:00