Harmonization of the Volume of Interest Delineation among All Eleven Radiotherapy Centers in the North of France

Abstract

BackgroundInter-observer delineation variation has been detailed for many years in almost every tumor location. Inadequate delineation can impair the chance of cure and/or increase toxicity. The aim of our original work was to prospectively improve the homogeneity of delineation among all of the senior radiation oncologists in the Nord-Pas de Calais region, irrespective of the conditions of practice.MethodsAll 11 centers were involved. The first studied cancer was prostate cancer. Three clinical cases were studied: a low-risk prostate cancer case (case 1), a high-risk prostate cancer case (pelvic nodes, case 2) and a case of post-operative biochemical elevated PSA (case 3). All of the involved physicians delineated characteristically the clinical target volume (CTV) and organs at risk. The volumes were compared using validated indexes: the volume ratio (VR), common and additional volumes (CV and AV), volume overlap (VO) and Dice similarity coefficient (DSC). A second delineation of the same three cases was performed after discussion of the slice results and the choice of shared guidelines to evaluate homogenization. A comparative analysis of the indexes before and after discussion was conducted using the Wilcoxon test for paired samples. A p-value less than 0.05 was considered to indicate statistical significance.ResultsThe indexes were not improved in case 1, for which the inter-observer agreement was considered good after the first comparison (DSC = 0.83±0.06). In case 2, the second comparison showed homogenization of the CTV delineation with a significant improvement in CV (81.4±11.7 vs. 88.6±10.26, respectively, p = 0.048), VO (0.41±0.09 vs. 0.47±0.07, respectively; p = 0.009) and DSC (0.58±0.09 vs. 0.63±0.07, respectively; p = 0.0098). In case 3, VR and AV were significantly improved: VR: 1.71(±0.6) vs. 1.34(±0.46), respectively, p = 0.0034; AV: 46.58(±14.50) vs. 38.08(±15.10), respectively, p = 0.0024. DSC was not improved, but it was already superior to 0.6 in the first comparison.ConclusionOur prospective work showed that a collaborative discussion about clinical cases and the choice of shared guidelines within an established framework improved the homogeneity of CTV delineation among the senior radiation oncologists in our region.

Delineation of the Prostate Bed: The “Invisible Target” Is Still an Issue?

“…After collecting each initial delineated volume and comparing these volumes with validated indexes [volume ratio (VR), volume overlap, and Dice similarity coefficient (DSC)], a second delineation was secondly performed after discussion of the slice results. For the selected case, VR and AV were significantly improved and DSC remained high, so the authors showed that a collaborative discussion about clinical case and the choice of shared guidelines (RTOG in this article) could improve the homogeneity of CTV delineation ( 37 ). Another study from the same team analyzed automated atlas-based segmentation supplied by software vendors compared to radiation oncologist contours for prostate bed cases.…”

“…Mitchell et al had showed that interclinicians variability in target volume outlining existed but adherence to evidence-based protocol (RADICALS protocol) can achieve reduction in this variability ( 36 ). Pasquier et al conducted in 11 RT centers a prospective work to improve homogeneity of delineation of volume of interest on 3 clinical cases of which a case for a postoperative prostate cancer ( 37 ). After collecting each initial delineated volume and comparing these volumes with validated indexes [volume ratio (VR), volume overlap, and Dice similarity coefficient (DSC)], a second delineation was secondly performed after discussion of the slice results.…”

Harmonization of practices between radiotherapy centres in the Nord and Pas-de-Calais regions (France): A three-year evaluation

“…The prostate cancer results have been previously published [8]. The indices were not improved for case 1 (low-risk recurrence cancer), for which the match was found to be satisfactory in the first comparison (DSC = 0.83±0.06).…”

“…The objective of our work is to improve the homogeneity of delineation between oncologist-radiotherapists in the regions of Nord and Pas-de-Calais (France) through discussions of clinical cases and the adoption of common published reference documents. The first results on prostate cancer have shown a quantifiable improvement in this harmonization [8], and a three-year follow-up assessment is presented here.…”

Evaluation of an ultrasound bladder scanner in supine and standing position

“…We refer to the study of Meijer et al 19 for bladder contouring interoperator variability on CT: they showed a σ reprod, operator (CT) of 11.8 cm 3 over a range of 50-250 cm 3 . Confirmation of their findings was sought by analyzing results of a previous study 20 : for this study, 14 operators contoured two pelvic treatment patients. The operators were radiation oncologists of different centers, thus representing different training, experience, and habits.…”