Is the use of a pre-operative computed tomography beneficial to reduce the interobserver variability of the CTVboost delineation for breast radiotherapy?

Publication date: Available online 4 March 2016
Source:Practical Radiation Oncology
Author(s): Karolien Verhoeven, Stephanie Peeters, Katrien Erven, Isabelle Kindts, Erik Van Limbergen, Hilde Janssen, Annouschka Laenen, Saskia Petillion, Caroline Weltens
PurposeTo determine whether the use of a pre-operative (pre-op) computed tomography (CT) reduces 1) the clinical target volume boost (CTVboost) and 2) the interobserver variability (IOV) of the delineated CTVboost in breast radiotherapy.MethodsIn patients treated with breast conserving therapy, 3 CT-scans in treatment position were performed: 1) pre-op, 2) after surgery, pre-chemotherapy (post-op) and 3) post-chemotherapy (post-chemo). Six radiation-oncologists delineated the tumorbed and CTVboost before and after fusion of the pre-op CT. To assess the IOV the Jaccard index (JI) was used. Linear mixed models were performedfor all analyses.ResultsEighty-two lumpectomy cavities were evaluated in 22 patients. No difference in CTVboost using the fusion of the pre-op CT (50.0cm³; 95%CI 35.6–64.4) compared to no fusion (49.0cm³; 95%CI 34.6–63.4) (p=0.6) was observed. A significant increase in IOV was shown with the fusion of the pre-op CT; the mean JI of the CTVboost delineation of post-op and post-chemo CT together without the fusion of the pre-op CT was 0.53 (95%CI 0.49–0.57) versus 0.50 (95%CI 0.46–0.53) with fusion (p<0.0001).ConclusionThere is no benefit of using a pre-op CT to reduce the volume or the interobserver variability of the delineated CTVboost for breast radiotherapy.



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