胸段食管癌放射治疗首次摆位误差分析研究

目的:利用锥形束CT(CBCT)分析不同分段食管癌患者放射治疗首次摆位误差。方法:在首次治疗前行CBCT验证,当平移误差<3 mm且旋转误差<3°时实施治疗;当平移误差>3 mm,<5 mm,在线纠正,再次行CBCT扫描,如果误差<3 mm实施治疗,否则需要重新摆位,重新验证。利用SPSS软件分析胸上段、胸中段及胸下段食管癌摆位误差。结果:胸上段、胸中段及胸下段食管癌首次摆位误差合格率分别为82.62%、79.59%和75.41%,再次摆位共8例,占比分别为2.94%、0.68%和6.56%。胸上段X轴、Y轴及Z轴误差与胸中段、胸下段误差差异无统计学意义。胸中段X轴、Z轴与胸下段治疗误差数据差异有统计学意义(t=-2.33,t=-4.46;P<0.05)。结论:在首次摆位中胸下段食管癌摆位误差略大于胸上段和胸中段食管癌,必要时可通过在线纠正和重新摆位减少摆位误差,提高治疗精度。

Analysis and research of the first-time positioning error of radiotherapy for esophageal cancer at thoracic segments

Objective:To use cone beam computed tomography(CBCT)to analyze the first-time positioning errors of radiotherapy for patients with esophageal cancer at different segments.Methods:CBCT was performed before the first treatment.When the translation error was less than 3 mm and the rotation error was less than 3°,the treatment was carried out.When the translation error was greater than 3 mm or less than 5 mm,CBCT scanning was performed again after on-line correction was carried out.If the error was less than 3 mm,the treatment was carried out.Otherwise,repositioning and re-verification need be implemented.The positioning errors of upper thoracic segment,middle thoracic segment and lower thoracic segment of esophageal cancer were analyzed by SPSS software.Results:The qualified rates of first-time positioning error of esophageal cancer at upper thoracic segment,middle thoracic segment and lower thoracic segment were 82.62%,79.59%and 75.41%respectively.And 8 cases were re-positioning,and the repositioning rates at three segments were 2.94%,0.68%and 6.56%respectively.There were no significant difference in positioning errors of esophageal cancer at X,Y and Z axis among upper,middle and lower thoracic segment.There were statistical significance in the differences of positioning errors of esophageal cancer at X axis and Z axis between middle and lower thoracic segment(t=-2.33,t=-4.46,P<0.05).Conclusion:In the first-time positioning,the positioning error of esophageal cancer at the lower thoracic segment is slightly larger than that at upper thoracic segment and middle thoracic segment.When it is necessary,online re-verification and re-positioning can reduce the positioning error and improve the accuracy of treatment.