Performance of a Fluorescent Screen with a CCD System for Quality Assurance in a Heavy-ion Beam Scanning Irradiation System

A two-dimensional dosimetry system was developed for the quality assurance (QA) of therapeutic scanned ion beams at Heavy Ion Medical Accelerator in Chiba (HIMAC). This system consists of a fluorescent screen and a charge-coupled device (CCD) camera. To evaluate the performance of this system, we carried out a few experiments concerning QA procedures. A verification of this system was also carried out by comparing the film dosimetry and the ionization chamber array. Also, we verified several types of corrections for errors, e.g., background and vignetting, that distort the measurement results. As a result, we confirmed that this system could be used for QA procedures of the therapeutic scanned ion beams.