外扩胃和十二指肠轮廓提高放射治疗自动勾画安全性的效果

目的 探讨自动勾画的危及器官（organ at risk, OAR）外扩对各类型剂量评估参数的影响。方法 收集2019年至2021年复旦大学附属中山医院放疗科收治的接受上腹部放疗的50例患者的CT图像，自动和人工勾画胃和十二指肠。采用Mann-Whitney U检验评估胃和十二指肠自动勾画戴斯相似系数（Dice similarity coefficient, DSC）、95%豪斯多夫距离（95%Hausdorff distance, HD95）的差异。结合临床常用剂量分布，计算胃和十二指肠自动勾画与人工勾画的剂量差异。采用Wilcoxon秩和检验评估不同外扩距离引起的剂量评估参数差异的变化。采用bootstrap法计算各差异均值95%CI的下限。分析所需的最小外扩距离，使得外扩后的结构所对应的剂量评估参数大于或等于手动勾画OAR的剂量评估参数。结果 胃的DSC和HD95均优于十二指肠，差异有统计学意义（P<0.001）。相邻外扩距离引起的最高剂量差异有统计学意义（P<0.001）。在DSC>0.8情况下，外扩约7 mm可以保证外扩结构的最高剂量大于或等于手动勾画OAR...

Effect of expanding stomach and duodenum to improve the safety of auto-contouring in radiotherapy

Objective To investigate how various dose evaluation parameters have changed because of the expansion of auto-contouring Organs at Risk (OAR). Methods The stomach and duodenum were automatically and manually contoured on the CT scans of 50 individuals who had upper abdominal radiotherapy within the previous three years. Mann-Whitney U test was used to assess the difference between stomach and duodenum auto contouring results in terms of Dice similarity coefficient (DSC) and 95% Hausdorff distance (HD95). To calculate the dose difference induced by auto contouring with the clinically applied dose distribution. The Wilcoxon rank sum test was utilized to evaluate the variation of the dose evaluation parameters caused by the different expansion distance. The calculation of the lower limits of the 95% confidence interval for each difference averages. To find the minimum expansion distance required when the dose evaluation parameter corresponding to the expanded structure was greater than or equal to that for the manual contoured OAR. Results The DSC and HD95 of stomach were superior to those of the duodenum and the Mann-Whitney U test revealed that there was a significant difference. The expansion procedure had a substantial impact on the difference in the maximum dose. The Wilcoxon rank sum test was employed to compare the results between any adjacent groups, and the p value was 0. The expansion procedure had no effect on the mean dose difference or V₃₀ difference. The maximum dose of the expanded structure can be guaranteed to be larger than or equal to the manually contoured OAR when the outer expansion is around 7mm, and it can be guaranteed that difference will not be greater than 1Gy, even if it is less than the OAR that was manually contoured when the outer expansion is 5mm and when the DSC is greater than 0.8. Conclusions The maximum dose will change as the auto contoured OAR expanded, and the mean dose and DVH parameters will not. Studies have confirmed that a certain distance of expansion can ensure that the maximum dose corresponding to the expanded structure is greater than or equal to the maximum dose corresponding to the manually contoured OAR.