A fast monitoring system for radiotherapeutic proton beams based on scintillating screens and a CCD camera

A facility in which a 62 AMeV proton beam is employed in the radiotherapeutic treatment of several ocular diseases is active since March 2002 at Laboratori Nazionali del Sud. A fast and accurate quality control system of such beam has been designed and tested. The system consists of a scintillating screen mounted perpendicularly to the beam axis at a fixed distance and observed by a highly sensitive CCD camera. The basic idea is the possibility to obtain real time information about the relative spatial dose distribution delivered to tissue through the measurement of the light emission in the scintillating screen. A comparison with the actual dosimetric system (a motorized silicon diode) that, in the future, will be replaced by the device introduced in this work (if its experimental performance will be successful) has been carried out. The good capabilities of the system make it worthy of further investigations on its applicability in proton beam monitoring for radiotherapeutic treatments (i.e. reconstruction of depth dose distribution and beam monitoring during patient irradiation).