The use of Multi-Leaf Collimators (MLC) in radiotherapy treatments allows to shape the radiation field to the target volume, exploiting the potential therapeutic gain of a better spatial localisation of the radiation beam. Therefore, it is essential to be able to fully characterise the dosimetrical properties of these devices, including the proper Monte Carlo modelling of its physical properties. This work describes the development and validation of a calculation model for a Siemens ModuLeaf mini MLC using a modified EGSnrc Monte Carlo platform. This environment was developed as a Monte Carlo...