乳腺癌术后胸壁及锁骨上区混合调强放射治疗技术的剂量学研究

Dosimetry study in Hybridintensity modulated radiotherapy after breast cancer surgery

目的探讨乳腺癌术胸壁及锁骨上区两种照射模式的剂量学特点,为临床选择提供参考。方法选取10例乳腺癌伴锁骨上区淋巴结转移的患者,分别设计三维适形计划(3DCRT)和混合逆向调强计划(Hy-IMRT),计划靶区(PTV)处方剂量为50 Gy分25次。利用剂量体积直方图(DVH)评价两种计划的靶区剂量、均质性指数(HI)及危及器官(OAR)的受量。结果Hy-IMRT靶区的近似最大剂量D2%分别为明显低于3DCRT(t=-9.821,P<0.05),近似最小剂量D98%明显高于3DCRT计划(t=3.879,P<0.05);混合调强计划靶区剂量均质指数(HI)明显好于3DCRT计划(t=-7.657,P<0.05);靶区平均剂量Dmeam两种计划之间无统计学意义。患侧肺的V20、V30混合逆向调强计划明显低于适形计划(t=-3.401、-4.117,P<0.05),其他危及器官受量无差异。结论胸壁及锁骨上区混合调强技术计划在剂量分布、危及器官保护、HI等方面都好于3DCRT计划。

Objective To evaluate the dosimetric benefits of the hybridintensity modulated radiotherapy （Hy-IMRT） after breast- conserving surgery. Methods For each of 10 chosen patients with breast cancer,three-dimensional conformal radiotherapy （3DCRT） and Hy-IMRT were designed. The prescribed dose for planning target volume （ PTV ） was 50 Gy/25f. Dosimetric comparisons of PTV dose distribution, homogeneity index （ HI ） and dose of organs at risk （OAR） between the two plans were performed on each patient by dose volume histogram （DVH）. Results The D2% of Hy-IMRT was statistically lower than that of 3DCRT（ t = -9. 821, P 〈 0. 05 ）, and the D98% was statistically higher than that of 3 DCRT（ t = 3. 879,P 〈 0. 05 ） ;The HI of Hy-IMRT was statistically lower than that of 3DCRT（ t = -7. 657 ,P 〈0. 05） ;There was no signifeicant difference in the mean dose（ Dmean ） between the two plans. The lung （ V20 ,V30 ） in Hy-IMRT paln was lower than 3 DCRT plan（ t = - 3. 401, -4. 117, P 〈 0. 05 ）. There was no statistical difference of ex- posure dose to other OARs between the two plans. Conclusion Hy-IMRT can improve target dose uniformity, HI and protect the organs at risk well compared to the 3DCRT in patients with breast eancer after the breast-conserving surgery.