SU-F-T-33: Air-Kerma Strength and Dose Rate Constant by the Full Monte Carlo Simulations

2016 ◽  
Vol 43 (6Part13) ◽  
pp. 3469-3469
Author(s):  
S Tsuji ◽  
M Oita ◽  
N Narihiro
2018 ◽  
Vol 45 (11) ◽  
pp. 5283-5292 ◽  
Author(s):  
Abner D. Soares ◽  
Lucas Paixão ◽  
Alessandro Facure

2012 ◽  
Vol 39 (1) ◽  
pp. 40-47 ◽  
Author(s):  
Guillaume Guérin ◽  
Norbert Mercier

Abstract The determination of gamma dose rates is of prior importance in the field of luminescence dating methods. In situ measurements are usually performed by the insertion of dosimeters or a portable gamma spectrometer cell in sediments. In this paper, Monte-Carlo simulations using the Geant4 toolkit allow the development of a new technique of insitu gamma dose rate evaluations: a spectrometer cell is placed on the surface of sediments under excavation to acquire successive spectra as sediments are removed by excavations. The principle of this non-invasive technique is outlined and its potential is discussed, especially in the case of environments in which radioelements are heterogeneously distributed. For such cases, a simple method to reconstruct gamma dose rate values with surface measurements using an attenuator is discussed, and an estimation of errors is given for two simple cases. This technique appears to be applicable, but still needs experimental validation.


Author(s):  
A Mozaffari ◽  
M Ghorbani

Objective: Brachytherapy sources are widely used for the treatment of cancer. The report of Task Group No. 43 (TG-43) of American Association of Physicists in Medicine is known as the most common method for the determination of dosimetric parameters for brachytherapy sources. The aim of this study is to obtain TG-43 dosimetric parameters for 60Co, 137Cs, 192Ir and 103Pd brachytherapy sources by Monte Carlo simulation. Methods: In this study, 60Co (model Co0.A86), 137Cs (model 6520-67), 192Ir (model BEBIG) and 103Pd (model OptiSeed) brachytherapy sources were simulated using MCNPX Monte Carlo code. To simulate the sources, the exact geometric characterization of each source was defined in Monte Carlo input programs. Dosimetric parameters including air kerma strength, dose rate constant, radial dose function and anisotropy function were calculated for each source. Each input program was run with sufficient number of particle histories. The maximum type A statistical uncertainty in the simulation of the 60Co, 137Cs, 192Ir and 103Pd sources, were equal to 4%, 4%, 3.19% and 6.50%, respectively. Results: The results for dosimetry parameters of dose rate constant, radial dose function and anisotropy function for the 60Co, 137Cs, 192Ir and 103Pd sources in this study demonstrated good agreement with other studies. Conclusion: Based on the good agreement between the results of this study and other studies, the TG-43 results for Co0.A86 60Co, 67-65200 137Cs, BEBIG 192Ir and OptiSeed 103Pd sources are validated and can be used as input data in treatment planning systems (TPSs) and to validate the TPS calculations.


Author(s):  
Shiqin Su ◽  
Parmveer Atwal ◽  
Julio Lobo ◽  
Cheryl Duzenli ◽  
I Antoniu Popescu

Abstract The purpose of this study is to present a novel method for generating Monte Carlo 4D dose distributions in a single DOSXYZnrc simulation. During a standard simulation, individual energy deposition events are summed up to generate a 3D dose distribution and their associated temporal information is discarded. This means that in order to determine dose distributions as a function of time, separate simulations would have to be run for each interval of interest. Consequently, it has not been clinically feasible until now to routinely perform Monte Carlo simulations of dose rate, time-resolved dose accumulation, or EPID cine-mode images for VMAT plans. To overcome this limitation, we modified DOSXYZnrc and defined new input and output variables that allow a time-like parameter associated with each particle history to be binned in a user-defined manner. Under the new code version, computation times are the same as for a standard simulation, and the time-integrated 4D dose is identical to the standard 3D dose. We present a comparison of scintillator measurements and Monte Carlo simulations for dose rate during a VMAT beam delivery, a study of dose rate in a VMAT Total Body Irradiation plan, and simulations of transit (through-patient) EPID cine-mode images.


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