双侧乳腺癌保乳术后调强放射治疗三种设野策略的比较研究

目的:探讨三种不同的调强放疗技术（两种不同切线野及近似均分野）在双侧乳腺癌保乳术后放疗中靶区剂量分布和正常组织受量的优劣。方法:选取10例经我科治疗的双侧乳腺癌保乳术后放疗的病例。重新设计三组计划:计划A为切线野左右乳腺分别调强；计划B为切线野左右乳腺整体调强；计划C为近似均分野调强。评估3种不同调强技术的均一度和适形度，并评估其肺、心脏重要正常组织受量。结果:三组计划的HI分别为1.10、1.09和1.09；CI分别为0.82、0.83和0.86，单因素方差分析三组结果无统计学差异。A、B、C三组计划的双肺V20（%）分别为26.74±4.83，34.28±3.75，31.40±9.01；V10（%）分别为40.70±4.56，72.42±5.151， 62.90±11.22；V5（%）分别为57.72±6.17，88.68±5.48， 82.04±5.28；平均剂量分别为13.10±1.89，18.14±1.35，16.38±2.01。计划A的V10和V5较计划B和C低（P=0.000，0.002），平均剂量也较低（P=0.002，0.032）。计划A的心脏受量亦较低，但与计划B、C比较没有统计学差异（P＞0.05）。结论:双侧乳腺癌保乳术后采用切线野分别调强并整合的调强放射治疗技术可明显减低正常肺组织的受照射剂量，特别是减少双肺低剂量区及双肺平均受照射剂量，进而降低放射性肺炎这一并发症。

Evaluation of the dose parameter for bilateral breast cancer after breast-conserving surgery using intensity modulated radiation therapy

Objective:To compare the dose parameter for bilateral breast cancer after breast-conserving surgery using three different radiotherapy techniques.Methods:10 cases of bilateral breast cancer treated by our department after breast-conserving surgery were selected and three groups of plans were redesigned.Plan A was to strengthen the breast on the left and right side of the tangent field respectively and integrate them into one plan.Plan B was to strengthen the breast on the left and right side of the tangent field as A whole,and plan C was to set the field intensity approximately.To evaluate the degree of uniformity and conformal of the three different intensity modulation techniques, and to evaluate the dose of important normal tissues of lung and heart.Results:The planned HI of group A,B and C was 1.10,1.09 and 1.09,respectively.Pairwise comparison showed no statistical difference.CI was 0.82,0.83 and 0.86,respectively,with no statistical difference in pairwise comparison.V20 of both lungs in group A,B and C was 26.74±4.83,34.28±3.75 and 31.40±9.01,respectively.V10 was 40.70±4.56,72.42±5.151,62.90±11.22,respectively.V5 was 57.72±6.17,88.68±5.48,82.04±5.28,respectively.The mean doses were 13.10±1.89,18.14±1.35,and 16.38±2.01,respectively.The V10 and V5 of plan A were lower than those of plan B and C(P=0.000,0.002) and the average dose was lower(P=0.002,0.032).The cardiac exposure of plan A was also lower,but there was no statistical difference compared with plan B and C(P＞0.05).Conclusion:Intensity modulated radiotherapy for bilateral breast cancer after breast-conserving surgery can significantly reduce the exposure dose of the lung,especially the low dose area of the lung and the average exposure dose of the lung.