SU‐E‐T‐161: SOBP Beam Analysis Using Light Output of Scintillation Plate Acquired by CCD Camera

Purpose: To analyze Bragg‐peak beams in SOBP (spread‐out Bragg‐peak) beam using CCD (charge‐coupled device) camera ‐ scintillation screen system. We separated each Bragg‐peak beam using light output of high sensitivity scintillation material acquired by CCD camera and compared with Bragg‐peak beams calculated by Monte Carlo simulation. Methods: In this study, CCD camera ‐ scintillation screen system was constructed with a high sensitivity scintillation plate (Gd2O2S:Tb) and a right‐angled prismatic PMMA phantom, and a Marlin F‐201B, EEE‐1394 CCD camera. SOBP beam irradiated by the double scattering mode of a PROTEUS 235 proton therapy machine in NCC is 8 cm width, 13 g/cm2 range. The gain, dose rate and current of this beam is 50, 2 Gy/min and 70 nA, respectively. Also, we simulated the light output of scintillation plate for SOBP beam using Geant4 toolkit. Results: We evaluated the light output of high sensitivity scintillation plate according to intergration time (0.1 ‐ 1.0 sec). The images of CCD camera during the shortest intergration time (0.1 sec) were acquired automatically and randomly, respectively. Bragg‐peak beams in SOBP beam were analyzed by the acquired images. Then, the SOBP beam used in this study was calculated by Geant4 toolkit and Bragg‐peak beams in SOBP beam were obtained by ROOT program. The SOBP beam consists of 13 Bragg‐peak beams. The results of experiment were compared with that of simulation. Conclusions: We analyzed Bragg‐peak beams in SOBP beam using light output of scintillation plate acquired by CCD camera and compared with that of Geant4 simulation. We are going to study SOBP beam analysis using more effective the image acquisition technique.