ESTRO 2023 - Abstract Book

S1376

Digital Posters

ESTRO 2023

5 years) blindly scored 25 randomly selected patients in terms of overall IQ and OARs’ boundaries visibility of the ORIG, N4ITK and N4ITK_AHE images, using a 4-point Visual Grading Analysis scale for the IQ, and a 5-point scale for the OARs. The examined OARs were prostate, bladder, rectum and small bowel. The IQ improvement was also quantitatively evaluated by computing the ratio between the pixels’ intensities standard deviation ( σ _ratio) post- and pre-filters application, and the ratio between the Shannon Entropy (SE_ratio) post- and pre-filters application, inside the body. Results Figure 1 illustrates the effect of filters application on an original image. As shown in Table 1, the application of the N4ITK and N4ITK_AHE with respect to the ORIG resulted mostly in either an improvement or no change of the IQ and the OARs visualization, for all the observers. However, the group O1&O2 scored overall higher as “‘no change/better” compared to the group with less experience. As regards the application of the N4ITK_AHE with respect to the N4ITK, the majority of the scores reflects again no changes or improvements in the rating. From a quantitative perspective, σ _ratio and SE_ratio were both less or equal to 1 for all the 73 patients, with a mean value of 0.72 and 0.93 in the N4ITK/ORIG comparison, respectively, and of 1 in the N4ITK_AHE/N4ITK comparison for both the metrics.