ESTRO 2025 - Abstract Book

S3783

Physics - Radiomics, functional and biological imaging and outcome prediction

ESTRO 2025

Figure 2 shows the average dose map. Most Figure 1B clusters are seen in medium-high dose areas but there are exceptions. The strongest femur effect (femur neck) does not coincide with the largest femur dose (heads). This is perhaps related to reduced oedema potential in dense head bone. The penis shows a surprisingly strong and consistent signal increase considering how low its dose is.

Conclusion: We show exploratory fMRI analyses have complementary value to traditional contour-based analyses as they can discover which (sub)regions are of interest. For example, in earlier work [3] , we averaged across the entire prostate, whereas Figure 1 shows the changes are driven by the peripheral zone specifically. Furthermore, unexpected effects were revealed such as in the low-dose penis. Classic fMRI analysis should be seen as complimentary to traditional contour-based approaches, as, at least for group level analyses , it can only be used for ‘registerable structures’, which for example excludes tumours and lymph nodes.

Keywords: MR-Linac, temporal analysis, fMRI

References: [1] Lueck CJ, Zeki S, Friston KJ, Deiber NO, Cope P, Cunningham VJ, Lammertsma AA, Kennard C, and Frackowiak RSJ (1989). The colour centre in the cerebral cortex of man. Nature; 340:386-389