Download Citation on ResearchGate | On Jan 1, , D. W.O. Rogers and others published BEAMnrc users manual }. BEAMnrc: software tool to model radiation beams. BEAMnrc is now part of EGSnrc. Report a problem or mistake on this page. Please select all. BEAMnrc, DOSXYZnrc and BEAMDP GUI users manual.
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It is generally accepted that the cross-section data available in the megavoltage energy range are sufficiently accurate. The major advantage of using aggressive VRTs is the significant improvement in calculation time without a compromise in the accuracy of the patient dose computation. Here, we investigate the efficiency enhancing methods and cross-section data available in the BEAMnrc MC code system and their effect on the accuracy of calculated fluence and dose distributions.
With photon interaction forcing, the user can force photons to interact up to a user-defined number of times, Nin specified component modules within a simulation. Monte Carlo, efficiency, variance reduction techniques, cross sections.
It is important to correctly define a measure of the overall uncertainty on the quantity of interest in order to accurately evaluate the efficiency of a particular MC simulation algorithm. The two MC programs generate accurate PHSP files of the linear accelerator for subsequent planning or dosimetric verification purposes in a relatively short amount of time when the appropriate efficiency enhancing tools are used.
Although significant differences in the mean energy, planar fluence, and angular and spectral distributions were observed when comparing the NIST and BH bremsstrahlung cross-section PHSP files, they were not reflected in the calculated dose distribution in a water phantom with and without an air gap. In addition, the methods for performing the efficiency and statistical uncertainty calculations are described. The results presented emphasize the importance of using a proper measure of the uncertainty on the quantity of interest in the calculation manjal the efficiency of a MC simulation.
An investigation of the beamnrv of different photon and bremsstrahlung cross-section data available in BEAMnrc on the accuracy of calculated fluence and dose distributions. There is another viewpoint concerning PHSP simulations of the linac treatment head, which should be beamndc. An additional phantom with a 5 cm air gap embedded in water was also simulated for dose computations. Springer-Verlag, Heidelberg,pp. The default differential cross section for the bremsstrahlung interactions is Bethe—Heitler BH.
In the megavoltage energy range, there are small but observable differences between the two differential cross sections refer to Fig. The efficiency of BEAMnrc PHSP simulations is significantly improved, with directional bremsstrahlung splitting combined with augmented charged particle range rejection, for the two beaknrc sizes studied. Augmented charged particle range rejection is only available when used simultaneously with DBS.
The tradeoff is that the no-VRT simulation is much slower, although if this simulation is being performed just once for subsequent use then it is a reasonable approach.
BEAMnrc, DOSXYZnrc and BEAMDP GUI users manual – NRC Publications Archive –
The percentage difference, in the central region of the field and at different depths, between measured and a selection of MC calculated off-axis dose profiles is also shown. A 3— Variance reduction techniques Bremsstrahlung photon splitting, Russian Roulette, and electron splitting The three options for bremsstrahlung photon bea,nrc were used in this study, i.
It has been reported that this option increases the efficiency of homogeneous phantom calculations, 38 however, no photon splitting or charged particle range rejection were employed. The percentage difference between measured and a selection of MC calculated central-axis dose profiles is also shown. The Bamnrc times were scaled to a single 2.
BEAMnrc: software tool to model radiation beams – National Research Council Canada
In our study, ESAVE was set to 2 MeV in all component modules with the exception of the target where the electron cutoff energy value was used, as recommended in Sheikh—Bagheri et al. In addition, the relative efficiencies are dependent on the quantity of interest chosen, although one can claim from this study that BEAMnrc MC calculations bsamnrc the directional bremsstrahlung splitting technique yields the highest efficiency for all quantities of interest analyzed.
This occurs because of particle correlations which are introduced with the use of VRTs, such as bremsstrahlung splitting. The percentage difference between the two MC calculations is also shown. Medical Physics, Windsor,pp. Therefore, if one is concerned with the smallest statistical uncertainty variance in dose, then it is best to perform the treatment head PS simulation without VRTs.
BEAMnrc: software tool to model radiation beams
Russian Roulette was also considered with the photon splitting techniques. The three options for bremsstrahlung photon splitting were used in this study, i.
The following efficiency enhancing methods were considered: For the first three uncertainty calculations, only one bin is considered, i.