Ⅰ期睾丸精原细胞瘤术后三维适形放疗与常规放疗的剂量学对比分析

Dosimetric analysis of postoperative three-dimensional conformal and conventional radiotherapy for stage I testicular seminoma

目的比较睾丸精原细胞瘤术后行三维适形放疗(3D-CRT)与传统放疗照射靶区及周围正常组织的剂量学差异。方法对12例确诊的Ⅰ期睾丸精原细胞瘤患者经腹股沟高位睾丸切除术后行术后放疗。利用治疗计划系统(TPS)为每例患者设计3D-CRT计划和虚拟常规计划(VCP)。应用剂量体积直方图(DVH)比较两种治疗计划的靶区适形度指数(CI)、不均匀性指数(HI)和正常组织受量。结果 3D-CRT计划的CI及HI均优于VCP计划,CI值分别为0.88±0.06和0.82±0.05,HI值分别为0.15±0.03和0.29±0.11(P<0.05)。3D-CRT计划的照射体积(IV)显著低于VCP计划,分别为(5268.20±1018.60)cm3和(5970.24±1471.49)cm3(P<0.05)。3D-CRT计划的小肠平均剂量以及V15低于VCP计划(P<0.05),睾丸的平均剂量低于VCP计划(P<0.05)。结论常规照射野是根据患者的骨性标志确定下来,未必适应于每个患者,3D-CRT更加个体化。此外3D-CRT在靶区覆盖率、剂量适形度及剂量均匀性方面均优于虚拟常规计划,同时降低了小肠低剂量照射体积和睾丸的散射剂量,这些剂量学方面的优势能否转换成临床受益还需要进一步临床验证。

Objective To compare the dose distribution of the three-dimensional conformal radiotherapy（3D-CRT）and con- ventional radiotherapy plan and explore the value of 3D-CRT in post-orchiectomy radiotherapy for stage l testicular seminoma. Methods After 12 cases diagnosed with stage I testicular cell tumors received high inguinal orchieetomy. And then postoperative radiotherapy were performed. 3D-CRT plan and virtual conventional treatment plans（VCP） were performed for each patient by the treatment planning systerm （ TPS ）. The confornlal index （ CI ） , heterogeneity index （HI） of each planning target volume （PTV） and the dose of normal organs were analyzed with the dose volume histogram （DVH）. Results The CI values of PTV were 0. 82 _± 0. 05 and 0. 88 ± 0. 06 in VCP and 3D-CRT,respectively. The HI values of FFV were 0. 29 ± 0. ll and 0. 15 ± 0. 03, respectively. 3D-CRT was superior to VCP （P 〈 0. 05）. The irradiation volum（IV） of 3D-CRT was lower than that of VCP（5268.20 ± 1018.60cm3 vs. 5970. 24 ± 1471.49era3 ,P 〈 0. 05）. As the mean dose and the ratio of dose volume V15 on the small intestine,3D-CRT was lower than virtual conventional treat- ment plans （P 〈 0. 05 ）. The mean dose of testis in 3D-CRT was lower than virtual conventional treatment（ P 〈 0. 05 ）. Conclusion Conventional radiation field is determined according to the signs of the patient~ bone, not necessarily suitable for each patient, while the 3D-CRT is more individualized. 3D-CRT is superior to VCP in both dose conformal degrees and dosimetry homogeneity, meanwhile reducing the dose and the volume of the small intestine and testis. Whether these dosimetric advantages can be converted into clinical benefit needs further clinical experiments.