Monte Carlo calculation of Varian 2300C/D Linac photon beam characteristics: a comparison between MCNP4C, GEANT3 and measurements

Monte Carlo study on a flattening filter-free 18-MV photon beam of a medical linear accelerator

“…These differences are consistent with the results reported from other investigations. 6,7,11 Large differences in out-of-fi eld regions could be due to the higher statistical uncertainty of MC results in that region because the dose of this region is delivered by low-intensity scattered radiation. Otherwise, although the statistical uncertainty of theMC results is about 1% for the fl at region of the beam profi le, it is increased up to 10% for out-of-fi eld regions.…”

“…5 Monte Carlo (MC) method is a powerful tool for analyzing linac head components and infl uencing factors on beam characteristics. 6,7 Thus, the effect of FF on photon energy spectra, depth doses, and beam profi les could be studied by an MC method. In an MC study on FF free beams, a dose rate increases of 2.31-fold (6 MV) and 5.45-fold (18 MV) and an out-of-fi eld dose reduction were reported.…”

Impact of backscattered radiation from the bunker structure on EPID dosimetry

“…This phenomenon is attributed mainly to the larger interaction area of the wall, and partly to the decrease in the mean energy of the beam for larger fields due to the contribution of more low‐energy photons from the head components (29) . It must be noted that the range of EPID response variations was less than 1% even for the large $18\times 18{ \text{cm}}^2$ fields at 150 cm SDD.…”

Estimation of organs doses and radiation-induced secondary cancer risk from scattered photons for conventional radiation therapy of nasopharynx: a Monte Carlo study

“…We used the Monte Carlo models of 60 Co and 6-and 9-MV photon beams that were built and validated in previous studies. [23][24][25][26] To take into account the therapy machines' head leakage-which make up part of the MIRD, medical internal radiation dose out-of-fi eld dose-the head shielding of all machines were added to our models. To validate the head shielding of linacs and the cobalt machine, the Monte Carlo models were run, and the relative doses in a cell at the distance of 1 m from the source were calculated; it was <0.1% of the dose at the center for a 10 × 10 cm 2 fi eld size for all models.…”