Development of a fast proton range radiography system for quality assurance in hadrontherapy

We describe the development of a Proton Range Radiography system with an imaging area of 30×30 cm2 for two dimensional mapping of the integrated density in a target. transmission radiographic images are produced by measuring, with a pair of position-sensitive detectors (GEM chambers), the direction of the protons transmitted through the patient and, with a stack of scintillators, the residual range of the protons leaving the patient. To match the data rate requirements of an in-beam diagnostic, a novel data acquisition system for the tracking detectors has been designed to operate at 1 MHz data flow. Laboratory tests exposing the GEM detector with high flux X-rays confirm the fast response of the new data acquisition system. Images of several phantoms have been recorded to demonstrate the GEM position accuracy.