基于肿瘤辐射敏感性的重离子适形调强放疗方案设计方法研究

Heavy ion cancer therapy is an advanced technique in radiotherapy and has been the current frontiers in basic and applied basic researches. Because the lethal effect of tumor cells is mostly concerned in radiotherapy, this study is aimed at elucidating the dependence of lethal effects of different radiosensitive tumor cells on the physical parameters of heavy ion radiation such as dose-averaged linear energy transfer (LET) through radiobiological experiments. Based on the experimental results, the strategy to design biologically-based radiotherapy plans for heavy ions will be established so as to achieve uniform biological effective doses across the target volume, leading to homogenious death of tumor cells in the target volume, thereby maximizing tumor control rate. The methodology of biologically-based radiotherapy plan design for heavy ions will be figured out. Finally, cell and animal radiobiological experiments under therapeutic conditions will be carried out to verify the reasonability of the new method. Through the systematic study mentioned above, a new and reasonable method is expected to be established for designing biologically-based conformal and intensity-modulated hevay-ion radiotherapy plans under the framework of passsive and active beam delivery systems. Because the radiosensitivity of tumor cells is considered during the design of treatment plans, this irradiation method is thought to improve the tumor control rate to a maximum extent in heavy ion radiotherapy. Therefore, this study is of importance to achieve heavy ion precision therapy, to make a full use of the adavantage of heavy ions in radiotherapy and to improve the efficacy of heavy ion therapy further.

重离子治癌是当今放射治疗领域先进有效的技术，已成为目前基础及应用基础研究中的前沿与热点。本项目旨在通过对放疗中最为关注的肿瘤细胞辐照存活效应的实验研究，阐明表征重离子辐射物理特性的参数剂量平均LET与具有不同辐射敏感性细胞表征其辐照存活效应参数之间的变化规律，在此基础上进行重离子放疗中肿瘤靶区生物有效剂量均匀达到靶区肿瘤细胞均匀致死、从而提高肿瘤控制率的放疗方案设计，构建基于肿瘤细胞辐射敏感性的重离子放疗方案设计的方法，最终由模拟治疗条件的细胞和动物实验验证放疗方案的合理性。通过上述内容的系统研究，形成在主动式及被动式束流配送系统下进行重离子适形调强放疗更为科学合理的新方法。这种考虑细胞辐射敏感性特点的放疗方法可最大程度地提高重离子治癌当中的肿瘤控制率，因而本项目研究对实现重离子精准治疗、充分发挥重离子应用于治癌的优势、进一步提高重离子治疗的疗效具有重要意义。

重离子治疗是放射治疗领域先进有效的治疗手段，重离子适形调强放疗方案的设计对其疗效起到非常重要的作用。本项目开展了基于肿瘤细胞辐射敏感性的重离子放疗方案设计方法研究，通过实验测量获得了重离子辐射场剂量平均LET与不同辐射敏感性肿瘤细胞存活率之间的关系，构建了基于肿瘤细胞辐射敏感性的重离子放疗方案设计方法，通过实验测量对构建的方法进行了验证。项目还进一步基于与辐射生物学效应直接相关的纳剂量学量构建了新的重离子辐射作用生物物理模型，该模型可应用于不同临床应用场景下的相对生物学效应的计算，并比同类模型的计算与实验值更加符合。本项目还提出了基于纳剂量学量进行优化新的重离子治疗计划设计思想，为后续研究奠定了基础。