Monte Carlo characterization of a multi-leaf collimator

Abstract

Monte Carlo simulations have been done to study the dosimetric characteristics of Multi Leaf Collimators (MLCs) used to modulate the photon beam intensity in radiotherapy treatments. A set of sweeping gaps and asynchronous sweeping gaps were simulated and the absorbed dose scored in a large voxel to integrate the effect of several leaves. Two MLCs with slightly different geometrical characteristics were studied. The dose obtained for the SG was proportional to the gap distance. On the other hand, a dose reduction was obtained for the aSG tests which presented a non-linear and a linear regions. Both SG and aSG were sensitive to the fine details of the leaf design