直接子野优化调强放疗方法治疗睾丸精原细胞瘤的剂量学探讨

Dosimetric study of intensity modulated direct aperture optimization radiation therapy for testicular seminoma

目的:比较直接子野优化调强放疗(direct aperture optimization intensity modulated radiation therapy,DAO-IMRT)与三维适形放疗(3D conformal radiation therapy,3D-CRT)对睾丸精原细胞瘤靶区(包括腹腔与盆腔)射野的衔接方法和剂量学特点,并分析其优劣。方法:选取7例睾丸精原细胞瘤,用Pinnacle治疗计划系统分别进行DAO-IMRT和3D-CRT的计划设计,通过等剂量曲线、剂量体积直方图(dose volume histogram,DVH)等参数来分析评价2种放疗计划的特点。结果:DAO-IMRT计划靶区热点和冷点的体积明显小于3D-CRT计划,其适形性指数(conformity index,CI)和均匀性指数(homogeneity index,HI)均明显优于3D-CRT计划。除左股骨头外其余危及器官(organ at risk,OAR)的平均剂量(Dmean)DAO-IMRT计划均小于3D-CRT计划,肝脏、双肾、小肠、直肠的V15(15 Gy剂量所涵括的照射体积)明显低于3D-CRT组,差异有统计学意义(P<0.01);而3D-CRT计划OAR的V5(5 Gy剂量所涵括的照射体积)均低于DAO-IMRT计划,其中双肾、小肠、膀胱、直肠、左股骨头及正常组织(normal tissue,NT)差异有统计学意义(P<0.05)。在机器跳数上DAO-IMRT计划较3D-CRT计划增加近1倍,差异有统计学意义(P<0.01)。结论:DAOIMRT放疗方法简单、安全可靠,能避免睾丸精原细胞瘤靶区射野的衔接,相比3D-CRT放疗方法具有明显的剂量学优势。

Objective To compare the field-matching techniques and dosimetric characteristics in the target area of testicular seminoma including the abdominal and pelvic cavities between direct aperture optimization intensity modulated radiation therapy （DAO-IMRT） and 3D conformal radiation therapy （3D-CRT）, and to analyse the advantages and disadvantages of DAO-IMRT. Methods DAO-IMRT and 3D-CRT plans were designed with Pinnacle treatment planning system for 7 testicular seminoma patients, and the characteristics of both the irradiation methods were analyzed and evaluated by means of the parameters like dose homogeneity indexes, dose volume histograms and etc. Results DAO-IMRT had the hot and cold volumes in the target areas both significantly smaller than those by 3D-CRT, while the conformity index and homogeneity index superior to those by 3D-CRT. The mean doses （Dmean） by DAO-IMRT of the organs at risk （OAR） except the left femur head were all lower than those by 3D-CRT, and the Vl5 values of liver, double kidney, small intestine and rectum by DAO-IMRT were statistically lower than those by 3D-CRT （P〈0.01）. 3D-CRT had the V5 values of OAR all lower than those by DAO-IMRT, in which the differences of double kidney, small intestine, bladder, left femur head and normal tissues were significant statistically （P〈0.05）. The monitor units by DAO-IMRT roughly doubled when compared with those by 3D-CRT, and the difference was also significant （P〈0.01）. Conclusion DAO-IMRT with easy operation and high reliability can avoid the connection of fields in the target area of testicular seminoma, and is superior to 3D-CRT in dosime- try. [Chinese Medical Equipment Journal ,2017,38（5） ： 103-106]