Produced by the UK’s Royal College of Radiologists, this website gives advice on which imaging modality is best suited to answer various clinical questions.
The European Society of Radiology has a large resource of educational exhibits and lectures.
This is a link to a concise explanation of the tumour–node–metastasis (TNM) staging system for cancer, the criteria required for the different T, N and M stages as well as a section on the difference between cancer grade and stage. Within the weblink there is a link to a set of associated multiple choice questions on the topic.
This weblink offers guidance on the use of intravenous contrast.