Interobserver variability (between radiation oncologist and radiation therapist) in tumor bed contouring after breast-conserving surgery

Abstract

Purpose: To examine interobserver variability between the radiation oncologist (RTO) and the radiation therapist (RTT) in delineating the tumor bed (TB) in early breast cancer (BC). Methods: We retrospectively analyzed patients who received a radiotherapy boost to the TB. In a first group, the clinical target volume (CTV) for the boost was the surgical bed, defined by using surgical clips. In a second group, the CTV was defined by identifying a seroma cavity or a metallic find on the scar. These contours were compared in terms of volume, number of slices, and Dice similarity coefficient (DSC). Results: Forty patients were assessed: 20 had surgical clips (group 1) while the other 20 had none (group 2). There was no difference in the number of slices contoured by the 2 operators for group 1, but a statistically significant difference emerged in the volumes: the RTT identified a TB that was a mean 45% smaller than the one identified by the RTO. Random differences were found between the 2 operators for group 2. The TBs delineated for this group were significantly larger ( P<0.05) than those identified by the RTT for group 1. The mean Dice value between the RTO’s and the RTT’s TBs was 0.69±0.07 (range 0.53–0.81) for group 1 and 0.37±0.18 (range 0–0.58) for group 2 ( P<0.05). Conclusions: This study showed that the use of clips coincided with less interoperator variability. With appropriate training, the RTT may play an important part in the multidisciplinary radiotherapy team.

Online adaptive MR-guided radiotherapy: Conformity of contour adaptation for prostate cancer, rectal cancer and lymph node oligometastases among radiation therapists and radiation oncologists

“…Countmaps of overlapping GTV and CTV-contours of all delineators were generated with voxel size 0.8 × 0.8 × 2 mm, in which interrater agreement per voxel is indicated by differences in color. We assessed volumetric differences in GTVs, CTVs and PTVs and calculated a Dice similarity coefficient (DSC) and conformity index (CI), also known as concordance index [5,14,18] for all study contours and the reference delineation in order to evaluate possible differences. Also, the generalized CI was determined [19], defined as the total of the common volumes between observer pairs divided by the total of the encompassing volumes between each observer pair.…”

“…In the pretreatment phase organ-at-risk (OAR) delineations are often performed by RTTs [5]. Following adequate training, RTTs achieve a good concordance with OAR contoured by ROs [6].…”

Advanced practice roles of therapeutic radiographers/radiation therapists: A systematic literature review

“…The three most-reported outcomes from AP roles were: enhanced service capacity, higher patient satisfaction, and safety maintenance. Only two studies 101,128 reported negative outcomes.…”

Evaluation of delineating the target volume by radiation therapists in breast cancer patients

“…The variability in CTV contouring for breast cancer patients between RO and RTT has been investigated in a small study with non-clinical data and was found to be low [5]. It has also been shown that with appropriate training, the RTT has a high potential to complete the tumor bed contouring after breastconserving surgery with the use of clips, as part of the multidisciplinary radiotherapy team [6]. By delegating the task of delineation from the RO/PA to the RTT, the planning process is expected to become more time efficient.…”