深层肿瘤重离子分野治疗技术及相关问题的探讨

目的：探讨重离子治疗深层较大射野肿瘤的分野定位与治疗方法。方法：①肿瘤患者体位设计与固定；②美国派克PQ-6000CT模拟定位机定位扫描及扫描数据传输；⑧利用瓦里安Eclipse放疗计划系统进行肿瘤靶区勾画及射野设计；④瓦里安21EX加速器配属的多叶光栅肿瘤照射靶区适形投射与射野勾画；⑤利用瓦里安21EX加速器和／或者核通Simulix-HQ模拟定位机肿瘤射野分野设计，射野间隔设计为2mm，并获取分野图形；⑥HIRFL重离子加速器治疗终端多叶光栅分野适形；⑦依次选择不同厚度的降能片对肿瘤分野进行分层照射。结果：负压垫、热塑膜或者负压垫＋热塑膜固定能够提高肿瘤患者体位重复固定和照射的准确性：CT模拟定位和放疗计划系统靶区勾画与照射野设计，能够保证肿瘤靶区不被遗漏和危及器官有效避让；重离子分野间隔设计为2mm有效避免了分野衔接区域剂量热点和冷点问题。结论：该方法解决了当前重离子加速器小野条件下治疗深部较大肿瘤问题，扩大了重离子肿瘤治疗范围，为今后重离子治疗的顺利开展奠定了一定的理论和实践基础。

The Technique and Related Questions of Heavy Ion Division Field Irradiation for Deep-seated Tumors

Objective:To investigate the field division and irradiation method of heavy ion radiotherapy for deep-seated and large tumor.Methods: ①Designing the treatment postures and fixing the patient;②Locating the tumor by Picker PQ-6000CT simulator machine and transferring the scan data to 3DCRT treatment planning system;③Drawing the target outline and designing radiation field by Varian Eclipse treatment planning system;④Projecting the radiation field on human or thermoplastic mask surface by the mulitleaf collimator and field light of Varian 21EX accelerator and drawing the target’s shape;⑤Designing the divided fields by Varian 21EX accelerator and(or) Nucletron Simulix-HQ simulator with an interval of 2 millimeter and receiving the fields’ shape;⑥Conforming divided fields by the mulitleaf collimator of treatment terminal of HIRFL accelerator;⑦Selecting the different thickness of degraders in turn and irradiating divided fields of tumor with heavy ion stratified technique.Results: Vacuum pad or(and) thermoplastic mask can improve the precision of re-fixation posture and radiotherapy.Locating the tumor by CT simulator machine and drawing the target outline and designing radiation field by 3DCRT treatment planning system can ensure that the tumor target is not omitted and the risk organ is protected effectively.The design of an interval of 2 millimeter can prevent over or low dose at the juncture of the divided fields.Conclusions: The method resolves the problem of treating deep and large tumor under the conditions that carbon ion accelerator can only use small size field,and expands the range of heavy ion radiotherapy,and provides a certain theoretical and practical basis for the heavy ion treatment in future.