Heavy ion CT system based on the measurement of residual range distribution: Improvement of the optical detector system

We report on experimental results from the heavy ion CT (IonCT) system based on the measurement of residual range distribution; this technique was first investigated by Zygmanski et al. (2000) for proton beams. Experiments were done on the spatial and density resolution phantom by using ⁴He and ¹²C beams accelerated up to 230 MeV/u and 400 MeV/u by the Heavy Ion Medical Accelerator in Chiba (HIMAC), installed in the National Institute of Radiological Sciences (NIRS) in Japan, with a high performance intensified charged coupled device (ICCD) camera. We show that rods with a diameter of 1 mm can be successfully reproduced using the ¹²C beam with this technique. We also show that the MCS blurring effect in the reconstructed image can be reduced for the heavier ion beam. The reduction in the background neutron noise from the phantom and/or collimator, by using the data obtained from the improvement of the optical detector system in 2007, is also shown.