Application Of Altas-Based Autosegmention Software In Esophageal Cancer

Objective: To evaluate the accuracy of atlas-based autosegmentation(ABAS)software when contouring critical organ-at-risk(OAR)in esophageal cancer,and assess the clinical feasibility of this technology.Methods: The CT images which included contoured OARs of 10 esophageal cancer patients treated with intensity-modulated radiotherapy(IMRT)were selected to establish ABAS reference atlas.From December 2015 to February 2016,10 new cases with stage III-IV esophageal cancer were randomized in this trial.The manual,single-template and multi-templates methods were adopted to contour their related OARs,respectively.Their morphological and dosimetric results were then compared.Wilcoxon signed-rank test was used for the comparison of their morphological indexes including the volume difference(?V%),the morphological consistency(Dice similarity coefficient and Overlap ratio)and the coordinates difference(?x,?y,?z).Correlation between the morphological consistency and OAR volumes was analyzed by Spearman method.And dosimetric endpoints of different coutour groups were compared using Friedmantest.Results: The average DSCvalues of single-template auto-contours and multitemplates auto-contours were0.83± 0.17 and 0.92 ±0.05,and the average ORvalues were 0.81± 0.17 and 0.92± 0.07,respectively.Significant differences were presented between them(P = 0.000,0.000).The coordinates displacements of multi-templates auto-contours in three directions were within 0.5cm,which is less than single-template ones.Spearman analysis found a positive correlation between DSC and OAR volumes.Thus the accuracy of single-template auto-contours is insufficient for spinal cord because of its small volume.The main dosimetric endpoints for the two auto-coutours were extremely similar to manual coutours.V20(%)for lung-all were 23.2 ± 9.0,22.4 ± 10.3 and 22.1 ± 9.9;Dmean(Gy)were 11.3 ± 4.0,11.1 ± 4.5 and 11.0 ± 4.3,respectively.For spinal cord,Dmax(Gy)showed 40.3 ± 4.8,38.2 ± 6.7,and 39.4 ± 5.3,respectively.And V30(%)for heart were 16.0 ± 14.7,15.8 ± 15.2 and 15.5 ± 14.4,respectively.The dose distribution showed no statistically significant difference between them(P > 0.05),and met the dose limit requirements of OARs for esophageal radiotherapy.Conclusion: The ABAS tool exhibits satisfactory accuracy for the OAR investigated in esophageal cancer with IMRT plans,which may potentially improve contour efficiency and reduce interoberserver variability.In addition,multi-templates method is better for clinical application.