The use of new delineation tool “Mirada” at the level of regional lymph nodes: Step-by-step development and first results for early-stage breast cancer patients

Purpose To describe the practical procedure of implementation and optimization of delineation of lymph nodes and organs at risk in early stage breast cancer patients, using “Mirada” software, as well as evaluation of the automatic segmentation for daily practice. Material and method Forty patients’ CT scans in treatment position were selected and recontoured according to the ESTRO guidelines. The atlas of dataset was then created for automatic delineation. Thirty patients with breast/chest wall and lymph nodes regions irradiated were recruited for evaluation. With the same treatment position, the CT scan images were acquired and then contoured by the Mirada system automatically as well as by the radiation oncologist manually (as the reference). The conformity index (CI) was used to evaluate the concordance between both of them. Results The mean time for manual contour was 24.1 ± 5.1 min and 26.4 ± 2.8 min for lymph nodes and organs at risk respectively. All volumes of interest were contoured using the software (including corrections) in 30 minutes, which reduced the time of delineation of target volumes and organs at risk by about 40%. Of the 30 cases evaluated, the mean CI of five main organs at risk was at least 0.8 while the automatic contour of lymph nodes was less satisfactory, with mean CI of 0.43 ± 0.1 (range: 0.23–0.52). Conclusion For breast cancer patients, the studied software permitted to save time for delineation with acceptable organs at risk contours. Improvement of lymph node regions contour is needed. More cases and further evaluation are needed for the system to realize its routine use.