[Evaluation of an automatic delineation system for organs at risk and target lymph nodes volumes for patients treated for breast cancer]

Purpose: Intensity-modulated radiotherapy needs the strict delineation of target volumes as well as organs at risk and the time used for this procedure is long. The purpose of this study was to evaluate the Workflow Box system (Mirada Medical, UK) for automatic delineation and segmentation for everyday use of organs at risk and lymph nodes delineation in patients treated for early stage breast cancer.

Material and methods: Twenty patients' CT scans in treatment position for their breast cancer radiotherapy were delineated in respect of the ESTRO delineation guidelines to begin the creation of automatic delineation atlas. Then 30 other CT scans were delineated this time by the automatic delineation system and by the radiation oncologist (reference delineation plan). The precision of the delineation was evaluated using the overlap volume index and evaluation of standard deviation (SD).

Results: The study of organs at risk has shown that the mean overlap volumes were between 0.49 (SD=0.21) and 0.97 (ET=0.03). Five organs at risk out of nine had overlap volumes at least 0.8. The mean overlap volume for all organs at risk was 0.77 (SD=0.17). The system was less performing for the lymph nodes with a mean overlap volume of 0.43 (SD=0.1) and ranging between 0.23 (SD=0.13) and 0.52 (SD=0.1). The use of this system reduced the delineation time by 40% per patient.

Conclusions: For patients with breast cancer, the system for automatic delineation and segmentation Workflow Box (Mirada Medical, UK) permitted to safely shorten the time for delineation with acceptable organs at risk delineation. Improvement of lymph node volumes is needed. A new evaluation will be realized after using the system in routine practice.