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

A facility in which a 62 MeV proton beam is employed in the radiotherapeutic treatment of several ocular disease has been 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 charge-coupled device 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 presently used dosimetric system (a motorized silicon diode) that, in the future, will be replaced by the device introduced in this paper (if its experimental performance will be successful) has been carried out. The good capabilities of the system make it worthy of further investigations into its applicability in proton beams monitoring for radiotherapeutic treatments (i.e., reconstruction of depth dose distribution and beam monitoring during patient irradiation).