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.