鼻腔NK/T细胞淋巴瘤行全脑全脊髓照射的放疗计划设计

Design of intensity-modulated radiotherapy plan for multi-target, multi-center and multi-stage

目的:探讨多靶区多中心多阶段调强放疗计划设计。方法:选取5例鼻腔NK/T(Natural Killer/T)细胞淋巴瘤且中枢神经系统侵犯的患者;采用头先进,仰卧位,双手置体侧,使用头颈肩热塑体模加胸腹热塑体模固定在一体板上的定位方式;对于不同的单次剂量和照射次数,采取同一计划多中心点的调强放疗设计,且以多阶段设计的方案设计物理计划;计划评估主要观察100%的剂量覆盖的靶区体积,以及靶区最大剂量点与最小剂量点;在计划执行之前,使用三维验证设备进行计划验证,采用3%,3 mm,10%的Gamma分析法。结果:将各阶段计划进行叠加,总计划在没有冷热点的情况下,100%临床处方剂量覆盖了95%的靶区体积,满足临床处方剂量要求;各阶段计划的相对剂量和绝对剂量的γ通过率都大于95%。结论:多靶区多中心多阶段的病例通过调强计划设计可实现靶区衔接处没有冷热点,剂量分布均匀。

Objective To study the design of intensity-modulated radiotherapy （IMRT） plan for multi-target, multi-center and multi-stage. Methods Five patients with nasal natural killer/T cell lymphoma and central nervous system （CNS） defect were selected. Each patient was examined in supine position, with both hands placed on the sides of body, and immobilized on a board by using head-neck-shoulder and thoracico-abdominal thermoplastic phantom. Patients＇ heads entered the equipment firstly. For different single-dose and radiation times, the IMRT plan with multi-center points were designed, and physical plan was design based on multi-stage plans. The target volume with 100% of dose coverage, the maximum and minimum doses of the target volume were mainly analyzed and evaluated. Before the execution of plan, three-dimensional verification device was used to verify the plan, and the Gamma analysis of 3%/3 mm, with a threshold of 10%, was applied. Results The sum of stage plans was the overall plan which satisfied the clinical dose requirement. In overall plan, 95% of the target volume was covered by 100% of clinical prescription dose under the condition without cold and hot points. All the Gamma pass rates of relative doses and absolute doses in stage plans were more than 95%. Concolusion IMRT can achieve uniformity on dose distribution and have not hot or cold points in connection of targets for multi- target, multi- center and multi-stage situation.