Development of high precision beam intensity control method for decreasing irradiation time in particle cancer therapy

本研究旨在探讨同步加速器中超快光束引出的控制方法。K. Torikai et al.，2009年。“三次共振”引出的光束具有时间结构，其中包含强的光束强度峰。峰值的频率约为50 Hz至500 Hz。该方法采用脉冲形加速电压来控制三阶谐振条件和Δp/p。在本研究中，组装了重复频率为6 MHz，最大脉冲电压为100 V，脉冲定时精度为2nsec的电源。该电源安装在同步加速器上，用于逐圈控制束流和引出的通断。用于粒子治疗的同步加速器中的束流循环频率在几MHz或几MHz左右，并且所提出的方法提供比电流控制方法快几十倍的束流控制。该方法可缩短1/10的辐照时间，尤其是在叠层辐照法中。通过本课题的研究，完成了电源、控制软件和仿真系统的组装。

This study aims for surveying ultra-fast beam extraction control method in synchrotron. A basic idea is proposed by K. Torikai et al. in 2009. The extracted beam by “third-resonance" has time structure, which contains strong beam intensity peak. The frequency of the peak is around 50Hz to 500Hz. The proposed method uses pulse-shape acceleration voltage in order to control the third-resonance condition andΔp/p.In this study, a repetition rate of 6MHz, maximum pulse voltage of 100V, pulse-timing accuracy of 2nsec power supply is assembled. When this power supply is installed in synchrotron, it serves for turn-by-turn controlling beam current and On/Off of extraction. Beam circulation frequency in synchrotron for particle therapy is around few or several MHz, and this proposed method provides beam control of few 10 times faster than current control method. This method serves for shortening the irradiation time by 1/10,especially in layer-stacking irradiation method. The power supply, control software and simulation system was assembled through this study.