ESTRO 2022 - Abstract Book

S1427

Abstract book

ESTRO 2022

Results Among the 14 patients, seven had “in field” and seven had “outside” second LR, none was “marginal”. The value of two histogram indices (SUV_Kurtosis and SUV_std) and two texture parameters (GLCM_Correlation, GLCM_Contrast) were significantly different between both groups (p < 0.05). In PCA, the first two dimensions expressed 78.51% of the total dataset variance. “In-field” and “Outside” were the best separated variables on the plane (i.e. explained the best the distance between individuals, Wilks test p < 0.02, [ figure 2 ]). “In-field” group corresponded to regions with high std and low Kurtosis, both features being associated with substantial signal heterogeneity. “Outside” group was associated with low GLCM_Correlation, std and GLCM_Contrast, suggesting rather homogeneous signal. The AHC analysis also found a cluster with high std, GLCM_Contrast, GLCM_Correlation, and low Kurtosis, corresponding to “In-field” patients. Kurtosis, std, GLCM_Contrast, GLCM_Correlation were not highly correlated (Pearson coefficient < 0.80).

Conclusion This study suggests that before reRT, FDG PET radiomics features characterizing the signal heterogeneity in the GTV to be re-irradiated have different values in patients who will relapse “in-field” or “outside”, with “in-field” relapses associated with higher metabolic heterogeneity in the GTV than relapse occurring outside the GTV. A validation study is ongoing.

Poster (digital): Implementation of new technology and techniques

PO-1634 QA of dose originating from deformable image registration of planning CT to CBCT on the Ethos system