乳腺癌保乳术后行IMRT和3D-CRT治疗的剂量学参数及靶区适形度比较

目的:通过配对比较早期乳腺癌保乳术后IMRT和3D-CRT两种放疗技术模式下靶区的适形度和肺组织的受照体积-剂量参数，探索早期乳腺癌保乳术后的最佳放疗模式。方法:选取20例 I-II期（T1-2N0M0）乳腺癌保乳术后行全乳腺放疗者，对同一患者分别设计IMRT和3D-CRT两套放射计划方案，配对分析PTV及PGTVbed靶区剂量分布适形度，患侧肺组织的受照体积-剂量参数，包括V5、V10、V20、V25、V30及肺组织和心脏平均受照剂量。结果:对比3D-CRT，IMRT使肺组织平均受照剂量降低了1.34 Gy，高剂量受照区域V20体积降低了2.89%，V25体积降低了5.57%，V30体积降低了7.45%；同时提高了PTV及PGTVbed靶区内的剂量分布适形度，差异均具有统计学意义（P<0.05）。两组的心脏平均受照剂量分别为（4.01±0.38）Gy和（4.61±0.42）Gy，差异无统计学意义（P>0.05）。结论:在早期乳腺癌保乳术后的辅助放疗中，采用IMRT模式比3D-CRT模式能够获得更好的靶区适形度，靶区内的剂量分布更均匀，有利于提高局控率，同时减少了肺组织的高剂量受照区域和平均受照剂量，对正常肺组织的保护更好，值得临床上应用和推广。

Comparison of metrological parameters and target conformity of IMRT and 3D-CRT after breast conservation operation

Objective:To explore the optimal radiotherapy mode for early breast cancer after breast conserving surgery by comparing the conformability of target area and the radiotherapy volume-dose parameters of lung tissue under IMRT and 3D-CRT two radiotherapy modes.Methods:A total of 20 patients with stage Ⅰ-Ⅱ(T_1-2N₀M₀)breast cancer after breast conserving surgery and received whole breast radiotherapy were collected.Two radiation planning schemes IMRT and 3D-CRT were designed for the same patient,respectively.The conformal index of the target area of PTV&PGTV bed and the radiation volume-dose parameters of the lung and heart tissue on the affected side,including V₅,V₁₀,V₂₀,V₂₅,V₃₀ and the average irradiated dose of the lung and heart tissue were analysed.Results:Compared with 3D-CRT,IMRT reduced the average radiation dose of lung tissue by 1.34 Gy,and the V₂₀ volume in the high-dose irradiated area decreased by 2.89%.V₂₅ volume decreasedby 5.57% and V₃₀ volume decreased by 7.45%.At the same time,the conformal index of dose distribution in the target area of PTV and PGTV bed was improved,and the differences were statistically significant(P<0.05).The mean cardiac dose of the two groups was(4.01±0.38)Gy and(4.61±0.42)Gy,respectively,with no statistically significant difference(P>0.05).Conclusion:In adjuvant radiotherapy after breast conserving surgery in early-stage breast cancer,adopting the model of IMRT than 3D-CRT model can obtain better conformal target,more uniform distribution of dose in the target area,to improve local control rate,at the same time reduce the lung tissue of high dose illuminated area and the average absorbed dose,and the protection of normal lung tissue is better,worthy of clinical application and promotion.