Ah, understood. Though the IDR has a number of pathology, histology, and OCT images and can cross link to SNOMED, we haven’t received any radiology submissions to date. Obviously, we’d be happy to take them!
This is likely due to the existence of more dedicated resources. For example, alongside the IDR, Nature recommends a number of medical image repositories, e.g.TCIA Collections - The Cancer Imaging Archive (TCIA) or https://www.smir.ch/.
Additionally, the Imaging Data Commons was recently announcened and lists a few resources that may work for you. @federov may be able to help you more.
All the best and good luck with your thesis.