The clinical evaluation of atlas-based auto-segmentation for automatic contouring during cervical cancer radiotherapy

Yi Li; Wenjing Wu; Yuchen Sun; Dequan Yu; Yuemei Zhang; Long Wang; Yao Wang; Xiaozhi Zhang; Yongkai Lu

doi:10.3389/fonc.2022.945053

The clinical evaluation of atlas-based auto-segmentation for automatic contouring during cervical cancer radiotherapy

Front Oncol. 2022 Aug 2:12:945053. doi: 10.3389/fonc.2022.945053. eCollection 2022.

Authors

Yi Li¹, Wenjing Wu², Yuchen Sun¹, Dequan Yu³, Yuemei Zhang¹, Long Wang¹, Yao Wang¹, Xiaozhi Zhang¹, Yongkai Lu¹

Affiliations

¹ Department of Radiation Oncology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.
² Department of Radiological Health, Xi'an Center for Disease Control and Prevention, Xi'an, China.
³ Department of Radiation Oncology, Tangdu Hospital, the Second Affiliated Hospital of Air Force Medical University, Xi'an, China.

Abstract

Purpose: Our purpose was to investigate the influence of atlas library size and CT cross-slice number on the accuracy and efficiency of the atlas-based auto-segmentation (ABAS) method for the automatic contouring of clinical treatment volume (CTV) and organs at risk (OARs) during cervical cancer radiotherapy.

Methods: Of 140 cervical cancer patients, contours from 20, 40, 60, 80, 100, and 120 patients were selected incrementally to create six atlas library groups in ABAS. Another 20 tested patients were automatically contoured with the ABAS method and manually contoured by the same professional oncologist. Contours included CTV, bladder, rectum, femoral head-L, femoral head-R, and spinal cord. The CT cross-slice numbers of the 20 tested patients included 61, 65, 72, 75, 81, and 84. The index of dice similarity coefficients (DSCs) and Hausdorff distance (HD) were used to assess the consistency between ABAS automatic contouring and manual contouring. The randomized block analysis of variance and paired t-test were used for statistical analysis.

Results: The mean DSC values of "CTV, bladder, femoral head, and spinal cord" were all larger than 0.8. The femoral head and spinal cord showed a high degree of agreement between ABAS automatic contouring and manual contouring, with a mean DC >0.80 and HD <1 cm in all atlas library groups. A post-hoc least significant difference comparison indicated that no significant difference had been found between different atlas library sizes with DSC and HD values. For ABAS efficiency, the atlas library size had no effect on the time of ABAS automatic contouring. The time of automatic contouring increased slightly with the increase in CT cross-slice numbers, which were 99.9, 106.8, 114.0, 120.6, 127.9, and 134.8 s with CT cross-slices of 61, 65, 72, 75, 81, and 84, respectively.

Conclusion: A total of 20 atlas library sizes and a minimum CT cross-slice number including CTV and OARs are enough for ensuring the accuracy and efficiency of ABAS automatic contouring during cervical cancer radiotherapy.

Keywords: atlas; auto-segmentation; automatic contouring; cervical cancer; radiotherapy.