Dosimetric image reconstruction in eye brachytherapy using silicon pixelated detectors

This study presents a high spatial resolution dosimetry system for quality assurance of I-125 eye plaques. The system is based on a silicon pixelated detector and is capable of deriving 3D dose distributions. A simple design was implemented, incorporating a movable eye plaque in a small water phantom above the silicon Medipix2 detector. It is designed for obtaining 2D dose distributions at different depths in water, for subsequent 3D dose mapping. The effect of backscattering in a medium placed behind the Medipix2 to simulate surrounding tissue has been studied in terms of dose distribution. Additionally, two modes of acquisition, event counting mode and the more complex time-over-threshold mode, were compared to the TG-43 protocol for the determination of their suitability for dosimetry.