Study of high quality 3D data acquisition in heavy ion CT using intensifying screen-EMCCD camera system

We have developed heavy ion computed tomography (HICT) system based on the measurement of residual range distribution using x-ray intensifying screen and charged coupled device (CCD) camera with Heavy Ion Medical Accelerator in Chiba (HIMAC) since 2000. In this system, there was the fluctuation of the beam-spill intensity as one of the problems which make the image quality poor. In order to improve it, the measurement of the beam intensity at every exposure is necessary to remove that affection. In 2008, we have developed the system which corrects projection data measured by HICT, using the monitoring information of the beam-spill. The fluctuation of beam intensity between each exposure was corrected, before the determination of the residual ranges. As a result, the fluctuation of range distribution decreased drastically. It was suggested that this correction was a useful method for the image quality improvement. (author)