32 – Transparent photon detector for the online monitoring of IMRT beams

Introduction: An innovative Transparent Detector for Radiotherapy (TraDeRa) has been developed for radiotherapy quality assurance (QA). It consists in a pixelated matrix of ionization chambers with a patented electrodes design. Each electrode is connected to in-house designed specific integrated circuits, providing a map of beam intensity and shape, at the linac pulse-scale. The detector aims at real-time monitoring of modulated beam upstream to the patient during delivery sessions, with a field cover up to 40 × 40 cm2. The work described here was realized on a 1:4 scale prototype in order to evaluate the dynamic of measurements, to characterize the raDeRa ability for detecting leaf position errors and to determine the impact of the detector presence on the photon beam.