The verification of the dose delivered to a patient during radiation therapy is a particularly important step for ensuring treatment quality. This step, known as in vivo dosimetry can be realized using a bidimensional dosimeter named Electronic Portal Imaging Device (EPID). However, few methods enable the determination of an accurate and fully personalized 3D dose distribution for the most current state of the art irradiation techniques. In this work, we propose a 3D dose reconstruction method based on Monte Carlo simulations allowing an accurate and fully personalized dose estimation from EPID device.