lumpectomy and adjuvant radiation at the Nova Scotia Cancer Center from July 2010 to December 2011. During breast conserving surgery, four surgical clips were placed on superior, inferior, lateral and medial walls of the lumpectomy cavity. Patients were imaged twice, first with CT for treatment planning and again between fractions 11 and 13 of the adjuvant radiation. To assess the effect of the clips on delineating using the same image data, in-house software was developed to digitally remove the clips from CT images using texture synthesis algorithm. Four radiation oncologists specializing in breast cancer treatment contoured the lumpectomy cavity volume, first with the clips digitally removed, and then several weeks later with the clips restored. Contours from three of the four participating radiation oncologists were included in the analysis, based on adherence to contouring guidelines. Contoured image sets were analyzed with regard to cavity volume, dimensions and concordance index. Statistical analysis was performed using a paired ttest. Results: The presence of clips significantly increased lumpectomy cavity volumes to 26.42 cc from 23.50 cc without clips (p < 0.0001). The presence of clips significantly increased the mean craniocaudal (CC), anteroposterior (AP) and lateral dimension by 7 mm, 2.3 mm, and 3 mm (all p < 0.01). Surgical clips improved consistency in delineation among observers in the craniocaudal dimension (p Z 0.005). Anteroposterior and lateral standard deviations were not affected significantly. There was also no significant difference in average concordance index with the presence of the surgical clips. Conclusions: The presence of surgical clips improves consistency of lumpectomy cavity delineation among radiation oncologists and also influences average delineated cavity volume and dimensions. Author Disclosure: S. Atrchian: None. P. Sadeghi: None. W. Cwajna: None. L. Helyer: None. D. Rheaume: None. M. Nolan: None. R. Rutledge: None. V. Calverley: None. S. Bennett: None. J. Robar: None.
Read full abstract