乳腺癌根治术后全X线照射胸壁及锁骨上区平卧位和胸骨水平位的肺剂量学比较

Comparison of lung dosimetry between supine and sternal horizon positions during X-ray irradiated radical mastectomy radiation therapy

目的:研究2种体位乳腺癌根治术后全X线照射胸壁及锁骨上区的肺剂量学差异,为进一步选择减轻肺放射性损伤的治疗体位提供理论依据。方法:回顾分析2006年1月至2014年12月在我院行乳腺癌术后胸壁及锁骨上区全X线切线野及单前野放射治疗的192例患者资料,其中平卧位92例,胸骨水平位100例,采集2组患者靶区等剂量曲线及肺剂量体积直方图,评价靶区覆盖度及肺剂量分布的差异。结果:平卧位组及胸骨水平位组90%处方剂量完全覆盖计划靶区,均达到放射治疗剂量学要求,靶区均匀指数及适形指数并无统计学差异(P>0.05);平卧位组及胸骨水平位组患侧肺V20分别为:(29.9±2.5)%和(32.4±3.2)%(P=0.000),患侧肺V30:(24.8±6.3)%和(26.8±1.9)%(P=0.002);患侧肺Dm:(16.4±3.0)Gy和(18.1±1.8)Gy(P=0.000);全肺V20:(14.6±2.1)%和(17.4±2.5)%(P=0.000),全肺V30:(8.4±1.6)%和(13.9±1.7)%(P=0.000);全肺Dm:(7.4±0.7)Gy和(8.2±0.7)Gy(P=0.000),差异均具有统计学意义。结论:乳腺癌根治术后全X线照射胸壁及锁骨上区,2种体位靶区覆盖度无明显差异;平卧位较胸骨水平位有更优的肺剂量分布。

Objective：To study the differences of lung dosimetry in chest wall and supraclavicular area under two commonly used radiation positions during all X-ray irradiated radicalmastectomy radiation therapy（RMRT）,and to provide theoretical references for choosing the optimal radiation position with reduced radioactive damage. Methods：Totally 192 patients from January 2006 to December 2014 treated with RMRT on chest wall,supraclavicular and infraclavicular region,were included in the retrospective analysis.Among them,92 patients were in supine position and 100 patients were in sternal horizon position. The coverage of target and dose distribution of lung were evaluated according to the isodose curve and dose volume histograms of two groups. Results：The radiation treatment was successfully completed conducted for all patients. The volume and dose for the supine and sternal horizon positions were as follows：（1）the ipsilateral lungs：V20,（29.9±2.5）% and（32.4±3.2）%（P=0.000）; V30,（24.8±6.3）% and（26.8±1.9）%（P=0.002）;Dm,（16.4±3.0）Gy and（18.1±1.8）Gy（P=0.000）.（2）the whole lung：V20,（14.6±2.1）% and（17.4±2.5）%（P=0.000）;V30,（8.49±1.6）% and（13.9±1.7）%（P=0.000）;Dm,（7.4±0.7）Gy and（8.2±0.7）Gy（P=0.000）. The above results showed a significant difference in the lung dosimetry between the supine position and sternal horizon position. Conclusion：There is no significant difference between the two positions in dose distribution for RMRT. Supine position have significantly better dose distribution for lung than sternal horizon position.