全中枢多中心放疗中铅门固定与跟随技术的应用研究

Application research of Carniospinal Irradiation Using Multi-ISO with Jaw Track or Jaw Fixed Technique

摘要:

目的 探讨全脑全脊髓多中心调强适形放射治疗（intensity modulated radiation therapy，IMRT）与容积弧形调强放射治疗（volumetric-modulated arcRadiotherapy，VMAT）计划中采用铅门固定与跟随技术的剂量学差异，为临床放疗技术选择提供指导与参考。 方法 选取陆军军医大学特色医学中心肿瘤科全脑全脊髓放疗患者14例，采用Elekta公司Monaco 5.11计划系统，每例患者分别设计多中心铅门固定静态调强（IMRT-MISO-SJT）、多中心铅门跟随静态调强（IMRT-MISO-JTT）、多中心铅门固定弧形调强（VMAT-MISO-SJT）、多中心铅门跟随弧形调强（VMAT-MISO-JTT）4种计划，比较其靶区、危及器官、正常组织受照剂量、500 cGy低剂量体积及机器跳数差异。 结果 四组计划均能满足临床要求，且靶区Dmean、D2%及D98%四组计划差异无统计学意义（P > 0.05）；VMAT-MISO-SJT计划中处方剂量覆盖靶区体积及靶区剂量适形度最好，与IMRT-MISO-SJT、IMRT-MISO-JTT差异均有统计学意义（P < 0.05），但与VMAT-MISO-JTT差异无统计学意义（P > 0.05）；VMAT-MISO-JTT靶区剂量均匀性最好，与IMRT-MISO-SJT差异有统计学意义（P < 0.05），但与IMRT-MISO-JTT及VMAT-MISO-SJT差异无统计学意义（P > 0.05）；IMRT-MISO-JTT计划中晶体最大剂量、心脏平均剂量最低，但与其他方案差异无统计学意义（P > 0.05）；IMRT-MISO-SJT左右肾脏平均剂量、机器跳数最低，与VMAT-MISO-SJT、VMAT-MISO-JTT差异有统计学意义（P < 0.05），但与IMRT-MISO-JTT差异无统计学意义（P > 0.05）。 结论 VMAT-MISO-SJT计划靶区剂量的HI、CI及Vpre优于IMRT-MISO-SJT及IMRT-MISO-JTT计划，但IMRT-MISO-SJT计划能更好降低左右肾脏平均剂量、500 cGy低剂量体积及机器跳数。全脑全脊髓的IMRT以及VMAT放疗计划中采用铅门跟随或者固定技术对靶区和危及器官的剂量分布及机器跳数无明显影响。

Abstract:

Objective To investigate the dosimetric differences between IMRT and VMAT in CSI （ Carniospinal irradiation ） using multi-ISO with static jaw technique or jaw tracking technique，so as to provide guidance and reference for the selection of clinical radiotherapy techniques. Methods 14 CSI patients were selected and treated with Elekta's Monaco 5.11 treatment planning system. Four plans were designed for each patient，including IMRT-MISO-SJT，IMRT-MISO-JTT，VMAT-MISO-SJT and VMAT-MISO-JTT.. The differences of target area，organ at risk，normal tissue dose，500cGy low dose volume and monitor units were compared. Results All the four groups of plans could meet the clinical requirements，and there was no significant difference in Dmean and D98% of the target area among the four groups of plans （P > 0.05）. VMAT-MISO-SJT had the best prescription dose volume covering target area （Vpre） and dose conformity index（CI） of target area，and had significant difference with IMRT-MISO-SJT and IMRT-MISO-JTT （P < 0.05），but had no significant difference with VMAT-MISO-JTT （P > 0.05）. The target dose homogeneity index （HI） of VMAT-MISO- JTT was the best，which showed significant difference with IMRT-MISO-SJT （P < 0.05），but showed no significant difference with IMRT-MISO-JTT （P > 0.05）. IMRT-MISO-JTT plan had the lowest maximum irradiation dose of lens and mean dose of heart，but showed no significant difference with other plans （P > 0.05）. IMRT-MISO-SJT had the lowest average dose of kidney and monitor units （MU），and had significant difference with VMAT-MISO-SJT and VMAT-MISO-JTT （P < 0.05），but had no significant difference with IMRT-MISO-JTT （P > 0.05）. Conclusion The HI，CI and Vpre of target dose of VMAT-MISO-SJT were better than that of IMRT-MISO-SJT and IMRT-MISO-JTT. However，IMRT-MISO-SJT plan could better reduce the mean dose of left and right kidneys，low-dose volume of 500cGy and monitor units. In craniospinal irradiation radiotherapy plans，static jaw technique and jaw tracking technique had no significant effect on the dose distribution and monitor units in IMRT and VMAT plans.