Measuring the leakage dose of TiGRT Dynamic MLC with EDGE diode dosimeter and EBT3 radiochromic film and comparing the results with BEAMnrc code calculations

One of the key factors in the assessment of the quality assurance in advanced radiotherapy treatments such as IMRT and VMAT is obtaining different types of dose leakages related to the MLCs used in these techniques. In this study, different dose leakage parameters from TiGRT Dynamic MLC, which was externally added to the lower part of the collimator system of Siemens linear accelerator, were measured using different dosimeters (diode dosimeter and radiochromic film) and compared with Monte Carlo simulation results. Measurement indices include radiation beam leakage from the air gap between the leaves (inter-leaf leakage), the amount of X-ray passage through individual leaves (intra-leaf transmission), average leakage and leakage related to the air gap of the leaves in the completely closed radiation field (abutting air gap leakage) were at  6-MV energy. In measuring the various leakage dose indices from TiGRT Dynamic MLC, a good agreement was observed between the measured data and the simulation results. According to the TG-50 protocol, the average interleaf leakage and interleaf leakage should be less than 2%; and the results of our study showed that the leakage parameters obtained from this type of MLC agree with the universal protocols.