全乳腺放射治疗3种照射技术对比

目的评价不同全乳腺放射治疗技术的剂量学优缺点。方法选取乳腺癌保乳术后患者10例,均为女性,年龄25～58岁,中位年龄42岁。用常规切线野、野中野调强、多野调强3种技术设计全乳腺放射治疗计划并进行剂量学对比。结果与常规切线野计划比较,野中野调强计划99%靶区体积含盖剂量从（4640±72）cGy增加到（4753±25）cGy;剂量不均匀指数从1.104±0.017下降到1.060±0.008。常规切线野计划与野中野调强计划在危及器官受量上的差异无统计学意义。野中野调强计划与多野调强计划在靶区剂量分布上的差异无统计学意义;与野中野调强计划比较,多野调强计划中心脏接受高于10Gy剂量的体积（V10）从（13.0±8.5）%增加到（53.3±22.7）%;同侧肺的V10从（25.2±3.4）%增加到（42.7±3.7）%;对侧乳腺、对侧肺、非特异正常组织的V5分别从（1.9±3.1）%增加到（32.6±2.3）%、从0到（18.5±8.3）%、从（9.9±1.0）%到（32.1±3.6）%。结论野中野调强技术较常规切线野技术明显改善靶区剂量分布;在此基础上多野调强技术未能明显进一步改善靶区剂量,但增加正常组织照射。

Comparative study on three kind techniques in whole breast radiation therapy

Objective To compare the dosimetric features of three kind whole breast radiation therapeutic techniques. Methods Ten patients of breast cancer received breast conserved surgery and whole breast irradiation were enrolled, all females, aged 25 - 58 years, median age 42 years. Three kinds of radiation plan were designed as conventional wedged tangential technique, field- in-field intensity modulated radiation therapy（IMRT） and multibeam IMRT. The dosimetric characters were compared among 3 plans. Results Compared with the conventional wedged tangential technique, the field-in- field IMRT plan had better dose distribution in the whole breast. The dose covering 99 % planning target volume（PTV）（D99） increased from （4 640 ± 72） cGy to （4 753 ± 25） cGy （P 0.05）; The heterogeneity index decreased from 1.104 to 1.060 （P 0.05）. There were no significant difference of dose irradiated to organs at risks in the conventional wedged tangential technique and field-in-field IMRT plan. There were no significant difference of dose distribution in PTV between the field-in-field IMRT plan and multibeam IMRT plan. Compared with the field-in-field IMRT plan, the multibeam IMRT plan increased the volume of normal tissues receiving low- dose. The volume of heart receiving dose more than 10 Gy（V10） increased from （13.0 ± 8.5） % to （53.3 ± 22.7） %（P 0.05）; The volume of ipsilateral lung receiving dose ,V10 , increased from （25.2 ± 3.4） % to （42.7 ± 3.7） %（P 0.05）; The V5 （the volume of receiving dose in contralateral breast,contralateral lung and mean healthy tissue ） increased from （1.9 ± 3.1） % to （32.6 ± 2.3） %, 0 to （18.5 ± 8.3） % and （9.9 ± 1.0） % to （32.1 ± 3.6） %（P 0.05,for all）. Conclusion It is demonstrated that the field-in-field IMRT plan provides better dose distribution than conventional plan, and the multibeam IMRT plan increases the volume of normal tissues receiving low-dose without further improving dose distribution base on field-in-field IMRT.