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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The initial number of histories was set to obtain approximately the same number of particles in the PHSP files, i.
This is essential if one is considering real-time MC simulation of the beaknrc head and patient. The parameter values chosen for the different techniques are recommendations from previous published works 1930 or are considered to be reasonable estimates, based on information from the BEAMnrc developers. In the megavoltage energy range, there are small but observable differences between the two differential cross sections refer to Fig.
BEAMnrc: software tool to model radiation beams
Table 2 Bremsstrahlung splitting techniques and the values used for the relevant parameters. 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. However, as demonstrated in Sec.
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. Efficiencies are shown relative to the efficiency obtained for the BEAMnrc default case. For both field sizes, the results were normalized to the linac calibration point in cGy per MU, i.
The percentage difference between measured and a selection of MC calculated central-axis dose profiles is also shown. A photon forced to interact is split into a scattered photon whose weight is equal to the probability of interaction and an unscattered photon carrying the remaining weight. Russian Roulette was also considered with the photon splitting techniques. Monte Carlo, efficiency, variance reduction beamnnrc, cross sections.
Data Tables 20 2— ; Springer-Verlag, Heidelberg,pp. In contrast, AEITs improve efficiency through the use of approximations.
When using only bremsstrahlung photon splitting, the greatest CPU time saving is when DBS is used with and without electron splitting, for both field sizes, i. The current version of BEAMnrc allows the user to choose three photon cross sections: It is generally accepted that the cross-section data available in the megavoltage energy range are sufficiently accurate.
The use of sophisticated variance reduction and approximate efficiency improving techniques, combined with parallel processing in computer clusters and the continuing increase in computing power, will help make MC-based treatment planning a mainstay option in radiation oncology departments. Bea,nrc the first three uncertainty calculations, only one bin is considered, i. When using UBS, each bremsstrahlung event produces a predefined number of bremsstrahlung photons, each having a weight equal to the inverse of the mqnual number NBRSPL times the weight of the electron that underwent the bremsstrahlung event.
Photon and bremsstrahlung cross sections The current version of BEAMnrc allows the user to beamndc three different photon cross sections: Data Tables 35 3manusl The mean energy and planar fluence were extracted from the PHSP in circular ring bins of equal area, the spectral distribution in energy bins of equal bin width, and the angular distribution in angular bins of equal bin width. Published online Nov 5.
There is another viewpoint concerning PHSP simulations of the linac treatment head, which nanual be considered.
BEAMnrc: software tool to model radiation beams – National Research Council Canada
If one uses VRTs e. Therefore, bdamnrc one is concerned with the smallest statistical uncertainty variance in dose, then it is best to perform the treatment head PS simulation without VRTs. The uncertainty was calculated in five different ways, i.
The following efficiency enhancing methods were considered: This occurs because of particle correlations which are introduced with the use of VRTs, such as bremsstrahlung splitting. The major advantage of using aggressive VRTs is manula significant improvement in calculation time without a compromise in the accuracy of the patient dose computation.
When photon splitting was ebamnrc together with the other techniques, only the cases with improved photon and electron fluence were considered, i. For both field sizes, the results are presented in Gy per incident particle. A 12 195— In addition, the relative efficiencies are dependent on the quantity of interest chosen, although one can claim from this study that BEAMnrc MC calculations with the directional bremsstrahlung splitting technique yields the highest efficiency for all quantities of interest analyzed.
BEAMnrc, DOSXYZnrc and BEAMDP GUI users manual – NRC Publications Archive –
Boundary crossing algorithm The boundary crossing algorithm together with the electron beammnrc algorithm constitutes the condensed history technique used by a particular MC code system.
This article has been cited by other articles in PMC. Amnual three options for bremsstrahlung photon splitting were used in this study, i. The photon forcing technique produces more photons, however, they are not statistically independent, thus yielding a lower efficiency although the corresponding PHSP file is generated the fastest. Support Center Support Center. Author information Article notes Copyright and License information Disclaimer.