早期乳腺癌患者术后不同体位调强放疗剂量的比较

Dosing of postoperative IMRT in different lying positions for early stage breast cancer

目的探讨早期乳腺癌患者保乳术后仰卧位与俯卧位调强放疗的剂量,旨在改善乳腺剂量均匀性。方法选取2013年6月至2015年6月江苏省沭阳县人民医院30例进行保乳术后放疗的早期左侧乳腺癌患者,均分别进行仰卧位与俯卧位的CT扫描,每例患者采用仰卧位与俯卧位进行切线2野照射,比较两种体位靶区剂量分布,右乳、心脏、左肺的受照体积及剂量,机器跳数。结果仰卧位与俯卧位所勾画的临床靶区体积之间的差异无统计学意义(P>0.05)。仰卧位大体肿瘤靶区(CTV)V_(105%)和D_(mean)显示<俯卧位,D_(max)显示>俯卧位,差异有统计学意义(P<0.05)。仰卧位计划治疗靶区(PTV)V_(95%)、V_(105%)、D_(mean)、D_(min)和D_(max)显著优于俯卧位,差异有统计学意义(P<0.05)。仰卧位照射野最大切肺深度为(2.9±0.8)cm,显著高于俯卧位的(1.3±0.4)cm,差异有统计学意义(P<0.05)。仰卧位的右侧乳腺V5显著低于俯卧位,心脏和左肺的照射剂量显著高于俯卧位,差异有统计学意义(P<0.05)。俯卧位的机器跳数为(582.4±117.9),仰卧位的机器跳数为(547.6±95.2),两种体位的机器跳数差异无统计学意义(P>0.05)。结论乳腺较大和乳腺下垂患者,俯卧位比仰卧位靶区剂量更为均匀,右乳、心脏和左肺的照射体积与剂量显著降低。

Objective To compare dose differences between supine and prone position postoperative intensity modulated radiation therapy（ IMRT） for early stage breast cancer to improve the distribution of radiation dose. Methods The study identified 30 early stage left breast cancer patients who underwent breast conserving surgery and received radiation therapy after the surgery in Jiangsu Cancer Hospital from June 2013 to June 2015. Every patient was performed CT scanning both in supine and prone position and every patient received radiation both in supine and prone position with two tangential fields irradiation. Target dose distribution and radiation volume and dose in right breast,heart,left lung in the two different lying positions were compared. Results There was no statistically significant difference in the delineated clinical target volume between the two lying positions（ P〉0. 05）; CTV V_（105%）and D_（mean）in the supine position was less than the prone position,while Dmaxdisplay was greater than the prone position,with a significant difference（ P〈0. 05）; V95%,V105%,D_（mean）,D_（min）,D_（max）and PTV in the supine position was significantly better than the prone position,with a significant difference（ P〈0. 05）; maximum irradiation lung cut depth in the supine position was 2. 9 ± 0. 8 cm which was significantly higher than that in the prone position（ 1. 3 ± 0. 4 cm） with a significant difference（ P〈0. 05）; Right breast V_5 in the supine position was significantly less than the prone position but irradiation dose in the sites of heart and left lung was significantly higher than the prone position,with a significant difference（ P〈0. 05）; the number of machine hops in the prone position was 582. 4 ± 117. 9; machine hop count in the supine position was 547. 6 ± 95. 2. There is no significant difference in machine hop count between the two positions（ P〉0. 05）. Conclusion For patients with larger and droop breast,target radiation dose in the prone position is more well-distributed than in the supine position,with irradiation volume and dose in the sites of right breast,heart and left lung decreased significantly.