应用不同热塑膜定位方式研究食管癌放疗中分次间及分次内摆位误差

Research on inter-fractional and intra-fractional setup errors of esophageal carcinoma radiotherapy with different thermoplastic film immobilization

目的对比分析采用头颈肩热塑膜真空袋和热塑体膜固定的颈段、胸上段食管癌患者在调强放射治疗过程中出现的分次间及分次内摆位误差,并探讨其原因。方法分别采用头颈肩热塑膜真空袋和热塑体膜对颈段、胸上段食管癌患者进行体位固定各30例,实行调强放射治疗,在每次治疗的摆位纠正前、摆位纠正后及治疗后获取锥形束断层扫描(CBCT)图像,将获取的CBCT图像与计划CT图像相匹配,得到分次间及分次内摆位误差,对其进行对比分析并探讨其原因。结果头颈肩热塑膜真空袋组的摆位纠正前误差为X(1.1±0.8)mm、Y(1.3±1.1)mm、Z(1.0±0.9)mm,热塑体膜组的摆位纠正前误差为X(1.7±1.4)mm、Y(4.5±3.2)mm、Z(3.9±1.5)mm,两组的分次间误差在X轴上差异无统计学意义(P>0.05),在Y、Z轴上差异有统计学意义(P<0.05);摆位纠正后与纠正前CBCT对比,头颈肩热塑膜真空袋组和热塑体膜组的摆位误差均明显缩小,差异具有统计学意义(P<0.05);治疗后与纠正后CBCT对比,头颈肩热塑膜真空袋组的摆位误差均有增加,差异具有统计学意义(P<0.05),热塑体膜组的差异不具有统计学意义(P>0.05)。结论颈段、胸上段食管癌患者采用头颈肩热塑膜真空袋固定技术精确性高于热塑体膜组;分次内误差在每次治疗过程中的变化明显,因此在治疗计划设计和实施过程中应予以充分考虑。

Objective To analyze and compare the inter-fractional and intra-fractional setup errors in radiotherapy for patients with cervical or upper thoracic esophageal carcinoma fixation between using head-neck-shoulder thermoplastic film vacuum bag or thermoplastic sheet. Methods 30 patients with cervical or upper thoracic esophageal carcinoma were divided into two groups. They were received radiotherapy fLxed by head-neck-shoulder thermoplastic film vacuum bag and thermoplastic sheet respectively. Patients received CBCT scans before initial setup, after re-positioning and after radiation delivery. The CBCT images were registered to the planning CT images, then obtained and analyzed the inter-fractional and intra-fractional setup errors. Results The before initial setup error of head-neck-shoulder thermoplastic film vacuum bag was X（1.1±0.8）mm, Y（1.3±1）mm, Z（1.0±0.9）mm. The before initial setup error of thermoplastic sheet was X（1.7±1.4）mm, Y（4.5±3.2）mm, Z（3.9±1.5）mm. The inter-fractional setup errors of two groups were not significant in X axis （P〉0.05）, but there were significant difference in Y and Z axis （P〈0.05）. Comparing with the before initial and after re-positioning CBCT scans, the setup errors of two groups were decreased obviously and the difference was significant （P〈0.05）, comparing with after radiation delivery and after re-positioning CBCT scans, the setup errors of two groups were increased. There were significant difference in head-neck-shoulder thermoplastic film vacuum bag （P〈0.05）, but not in thermoplastic （P〉0,05）. Conclusion The precision of radiotherapy for cervical or upper thoracic esophageal carcinoma fixed by head-neck-shoulder thermoplastic film vacuum bag is better than the thermoplastic sheet group. The variations of intra-fractional setup error were obvious during the treatment and should be taken into account.