Investigation of Leakage and Transmission Radiation through the MLC Version I۲ Applied To the Elekta Synergy ۶ MV Photon Beam Linac

Introduction: Radiotherapy and nuclear medicine extensively use Monte Carlo simulation to study particle transport and interactions. The aim of this task is the investigation and simulation of leakage and transmission (L&T) particles using the Multi-Leaf Collimator version i۲ applied to the Elekta Synergy linac.Material and Methods: In this study, all linac segments are included in the simulation model. In order to reduce MC calculation time, the new HPC-Slurm cluster platform and the Python phase space approach are used. To study the transmission between MLCi۲ leaves, a detailed analysis of the dose distribution was conducted.Results: The simulation results obtained with Gate ۹.۰ MC are excellently correlated with the measured data with error estimates for the ۶ MV photon beam parameters less than ۱% and a validation level of ۹۹% in terms of the gamma index's (۲%/۲mm) threshold formalism for the cross profiles and PDD's dose distributions. The results indicate that contamination particles (e-, e+) have an effect on the distribution of dose in the patient. These particles are present in the beam produced previously and which is assumed to contain only X-rays. In addition, a three-dimensional distribution of dose inside the tumor (CT-scan) confirms the L&T effect of the studied version of the multi leaf collimator (MLCi۲), with a dose range of around ۷۰% of the delivered dose to the tumor, resulting in secondary outcomes at the DNA.Conclusion: Consequently, the production of a new generation of MLC that can limit this L&T effect should be encouraged.