用于重离子放疗剂量和束流位置分布实时监测的新型数字化读出方法研究

The incidence and mortality rates of cancer have been rising for many years, it has become a serious social problem, humans have been continuously exploring various cancer treatment technology, and the heavy-ion radiotherapy has been verified as one of the best radiation therapy. With the continuous development of heavy-ion radiotherapy technology, the beam distribution of heavy-ion radiotherapy system gradually transformed into the point scanning with higher precision, this advanced way of distribution needs to be monitored real-time accurate dose and spatial distribution of the ion beam. Therefore，it requires that the front-end readout electronics for the integral ionization chamber has the characteristic such as high precision, wide range, good linearity and so on; and it requires that the front-end readout electronics for the multi-strip ionization chamber has the ability of multi-channel and rapid processing signal. To solve these problems, this project intends to research and design a new circuit of current-to-frequency converter for dose monitoring, and a new high-speed multi-channel charge-to-frequency converter ASIC for position monitoring, finally we will establish a principle prototype of a new digital readout system of the dose and beam position distribution real-time monitoring for the heavy-ion radiotherapy, and it realizes rapid digital readout of the exposure dose and the distribution of the beam position. Implementation of this project will help to effectively improve the monitoring accuracy of the dose and beam position distribution in the heavy-ion radiotherapy, it has important practical implications for the development of heavy-ion radiotherapy technology.

癌症的发病率及死亡率多年来一直持续上升，已成为一个严峻的社会问题，人类一直不断地探索各种治癌技术，重离子放疗已被验证为最佳的放射治疗方式之一。随着重离子放疗技术的不断发展，重离子放疗系统的束流配送方式逐渐转变为更高精度的点扫描，这种先进的束流配送方式需要实时精确监测重离子束的剂量和空间分布，进而对剂量监测的积分电离室和位置分布监测的分条电离室的前端读出电子学提出了更高要求：高精度、宽量程、良好线性、多通道并行快速处理。针对这些需求，本项目拟研究设计适用于剂量监测探测器的新型电流频率转换电路和束流位置分布监测探测器的新型高速多通道电荷频率转换专用集成电路，最终建立重离子放疗剂量和束流位置分布实时监测数字化读出系统原理样机，实现照射剂量与束流位置分布的快速数字化读出。通过本项目的实施，将有效提高重离子放疗剂量和束流位置分布的监测精度，对我国重离子放射治疗技术的发展具有重要的现实意义。

针对重离子放疗中实时精确监测重离子束的剂量和空间分布的迫切需求，进而对剂量监测的积分电离室和位置分布监测的分条电离室的前端读出电子学进行了新型快速数字化读出方法及技术的探索与研究。本项目研制了适用于剂量监测探测器的具有可变阈值电流积分泄放功能的电流频率转换电路，开展了单通道具有积分开关泄放功能的高速电荷频率转换ASIC电路原理的研究，探索了基于门控积分前端处理的技术路线的可行性，研制了用于束流位置分布监测探测器的基于新型ASIC器件ADAS1134的无死时间的多通道微弱电流数字化读出系统。最终研制出了重离子放疗剂量和束流位置分布实时监测数字化读出系统原理样机，性能优良，可实现照射剂量与束流位置分布的快速数字化读出。通过本项目的研究，能有效提高重离子放疗剂量和束流位置分布的监测精度，对我国重离子放射治疗技术的发展具有重要的现实意义。