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

摘要

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,aud the V15 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 dosimetry.%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:DAO-IMRT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.