乳腺癌保乳术后三种放疗技术剂量学评价

Dosimetric evaluation of CR,3D-CRT and IMRT for breast cancer after conservative surgery

目的:比较乳腺癌保乳术后常规放疗(CR)、三维适形(3D-CRT)放疗、调强适形(IMRT)放疗靶区剂量均匀性、危及器官受照体积等方面的差异。方法:随机选择10例乳腺癌患者,为每例患者设计上述三种照射技术的治疗计划。处方剂量为50Gy/25次。所有计划都使95%靶区体积达到处方剂量要求。根据积分剂量体积直方图(DVH)比较靶区受量和相关正常器官受量的差异和剂量分布。结果:CR、3D-CRT、IMRT靶区均匀性指数分别为1.16±0.03、1.15±0.03和1.14±0.02(P=0.279),适形度指数分别为0.61±0.05、0.65±0.06和0.69±0.06(P=0.025);三种放疗技术中患侧肺V30分别为19.39±3.09、15.53.±3.98、15.68±4.38(P=0.057),V20分别为22.26±3.52、18.87±4.24、20.68±4.52(P=0.202),V10分别为26.68±3.72、23.96±4.76、34.27±14.02(P=0.039),V5分别为33.71±3.70、31.66±5.49、49.81±24.25(P=0.018);对侧乳腺V3分别为3.31±3.74、2.37±3.11、14.24±3.81(P=0.007);心脏V5分别为19.99±17.22、13.77±11.10、38.42±29.95(P=0.037)。结论:与CR相比,3D-CRT和IMRT能够改善靶区均匀性和适形度,并降低患侧肺的高剂量受照体积,但IMRT同时增加了患侧肺、对侧乳腺、心脏低剂量受照体积。

Objective： To compare the dose distribution and volume histogram （DVH） of the planning target volume （PTV） and organs at risk（OAR） between conventional radiation therapy（ C R）, three-dimensional conformal radiation therapy （3D-CRT） and intensity modulated radiation therapy （IMRT） after breast-conserving surgery. Methods： For each of 10 randomly chosen patients, 3 plans were designed for 3 irradiation techniques. The prescribed dose was 50Gy/25f, 95% of the planning target volume received this dose. The cumulated DVHs and 3 D dose distributions of CR, 3 D-CRT and IMRT plans were compared. Results：The homogeneity indices of CR, 3 D-CRT, IMRT were 1.16 ± 0. 03,1.15 ± 0. 03,1.14 _± 0. 02 （P = 0. 279） while the conformity indices were 0. 61 ± 0. 05, 0. 65 ±0. 06,0. 69 ±0. 06（P =0. 025）, respectively. With regard to the organs at risk, the volumes of ipsilateral lung receiving 30% of the prescription dose （V30） were 19. 39 ± 3.09, 15.53 ± 3.98, 15.68 ± 4. 38 （ P = 0. 057）, those of V20 were 22. 26 ± 3.52,18. 87 ± 4. 24,20. 68 ± 4. 52 （P = 0. 202）, those of V10 were 26. 68 ± 3. 72,23.96 ± 4. 76,34. 27 ± 14. 02 （ P = 0. 039 ）, those of V5 were 33.71 ± 3.70,31.66 ± 5.49,49. 81 ± 24. 25 （P = 0. 018） and V3 of contralateral breast were 3.31 ± 3.74, 2.37 ± 3.11, 14. 24 ± 3.81 （P =0. 007） while V5 of heart were 19.99 ± 17.22,13.77 ± 11.10,38.42 ± 29.95 （ P = 0. 037 ）. Conclusion： Compared with CR, 3D-CRT and IMRT improved the homogeneity of PTV, reduced the the irradiated volume of ipsilateral lung receiving fairly high dose, while IMRT increased low dose volumes of ipsilateral lung, contralateral breast and heart.