CT模拟定位在宫颈癌术后辅助放射治疗中的必要性

目的 通过CT模拟定位技术制定照射野与“常规照射野”相比较来说明两者的优劣。方法2007年1月～2008年3月共19例宫颈癌术后患者行增强CT扫描。并在治疗计划系统（TPS）上按照骨性标志和血管CTV设定“常规照射野”和“CT照射野”．并分别比较不同等剂量曲线对PTV的包绕程度。结果“CT照射野”的靶区包绕程度明显优于“常规照射野”，前者95％等剂量曲线包绕PTV体积明显优于后者，其差值接近20％。而这种差异主要体现在“常规照射野”对髂总PTV和髂外PTV的遗漏。结论在常规X线模拟定位机下根据骨性标志来设定的“常规照射野”并不一定适合宫颈癌等盆腔肿瘤的外照射，因为它可能会遗漏一部分髂总、髂外淋巴结引流区以及部分瘤床。照射野必须根据增强CT来设定．最好是应用基于CT的虚拟模拟定位技术。

The importance of CT-simulation in postoperative radiotherapy of cervical carcinoma

Objective A part of cervical carcinoma required postoperative radiotherapy. The radiation field used to be based on bone mark of pelvis. However, the ＂conventional radiation field＂ could not involve all of the target volume. This study compared ＂conventional radiation field＂ and ＂CT-simulation radiation field＂ by CT-simulation technology on treatment planning system. Methods Total 19 patients with cervical carcinoma entered this study from January 2007 to March 2008. ＂Conventional radiation field＂ and ＂CT-simulation radiation field＂ were planned based on bone mark of pelvis and CTV, separately. And then the isodose curve involving PTV were compared with paired-samples T test. Results ＂CT-simulation radiation field＂ was superior to ＂conventional radiation field＂, and the 95% isodose curve involving PTV volume of the former was about 20% more than the latter. The difference was resulted by ＂conventional radiation field＂ missing a part of common iliac and external iliac lymph nodes. Conclusion The ＂conventional radiation field＂ may not fit all because it missed some common lilac and external iliac lymph nodes and tumor bed. The best radiation field should be based on CT-simulation.