The comparison between 6 MV Primus LINAC simulation output using EGSnrc and commissioning data

Abstract

IntroductionMonte Carlo calculation method is considered to be the most accurate method for dose calculation in radiotherapy. The purpose of this research is comparison between 6 MV Primus LINAC simulation output with commissioning data using EGSnrc and build a Monte Carlo geometry of 6 MV Primus LINAC as realistically as possible. The BEAMnrc and DOSXYZnrc (EGSnrc package) Monte Carlo model of the LINAC head was used as a benchmark.MethodsIn the first part, the BEAMnrc was used for the designing of the LINAC treatment head. In the second part, dose calculation and for the design of 3D dose file were produced by DOSXYZnrc. The simulated PDD and beam profile obtained were compared with that calculated using commissioning data. Good agreement was found between calculated PDD (1·1%) and beam profile using Monte Carlo simulation and commissioning data. After validation, TPR20,10, TMR and Spvalues were calculated in five different field.ResultsGood agreement was found between calculated values by using Monte Carlo simulation and commissioning data. Average differences for five field sizes in this approach is about 0·83% for Sp. for TPR20,10differences for field sizes 10×10 cm2is 0·29% and for TMR in five field sizes, the average value is ~1·6%.ConclusionIn conclusion, the BEAMnrc and DOSXYZnrc codes package have very good accuracy in calculating dose distribution for 6 MV photon beam and it can be considered as a promising method for patient dose calculations and also the Monte Carlo model of primus linear accelerator built in this study can be used as method to calculate the dose distribution for cancer patients.

Determination of the Small-Field Output Factor for 6 MV Photon Beam Using EGSnrc Monte Carlo

“…MC simulation was suggested to calculate the S p directly to avoid the inaccuracy in measurement by using the IC. [ 24 ]…”

“…The results shown were valid because previous studies mentioned that the MC simulation was often being used as a benchmark in dose calculation algorithm, especially in small-field dosimetry due to the ability of MC simulation to eliminate the uncertainties of the IC measurement such as lack of LEE, volume averaging effect, and partial source occlusion during simulation process. [ 9 13 24 ] A study by Yani et al . proved that the calculated S cp by the EGSnrc MC simulation was in good agreement with the IC-measured S cp in small-field size 3 cm × 3 cm with the percentage difference between the measured and calculated S cp of 1.8% which was within the tolerance range of 2%.…”