Automatic Segmentation of Whole Breast Using Atlas Approach and Deformable Image Registration

Abstract

Purpose-To compare inter-observer variations in delineating the whole breast for treatment planning using two contouring methods.Methods and Materials-Auto-segmented contours were generated by a deformable image registration-based breast segmentation method (DEF-SEG) by mapping the whole breast clinical target volume (CTVwb) from a template case to a new patient case. Eight breast radiation oncologists modified the auto-segmented contours as necessary to achieve a clinically appropriate CTVwb and then recontoured the same case from scratch for comparison. Times to complete each approach as well as inter-observer variations were analyzed. The template case was also mapped to 10 breast cancer patients with body mass indexes ranging from 19.1 to 35.9. Three-dimensional surface-tosurface distances and volume overlapping analyses were computed to quantify contour variations.Results-The median time to edit the DEF-SEG-generated CTVwb was 12.9 min (range, 3.4-35.9), compared to 18.6 min (range, 8.9-45.2) to contour the CTVwb from scratch (30% faster; p = 0.028). The mean surface-to-surface distance was noticeably reduced from 1.6 mm among contours generated from scratch to 1.0 mm using the DEF-SEG method (p = 0.047). Deformed contours in 10 patients can achieve 94% volume overlap prior to correction and required editing of 5% of the contoured volume (range, 1%-10%).Conclusions-Significant inter-observer variations suggest that there was a lack of consensus regarding the CTVwb, even among breast cancer specialists. Using the DEF-SEG method produced

Interobserver variation in parotid gland delineation: a study of its impact on intensity-modulated radiotherapy solutions with a systematic review of the literature

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