In the FRCS (Tr & Orth) structured oral exam, most candidates will have anticipated the possibility of being asked a radiology topic and would have (wisely) prepared for this. While candidates will be asked bits and pieces of radiology during a topic discussion the assumption that a stand-alone 5-minute radiology topic is probably too much detailed knowledge for the average candidate (and examiner) to stretch out discussion for is wrong. We know candidates who have had very detailed questioning on the principles of either bone scans or MRI scanners lasting the full 5 minutes of a viva. Bone and MRI scanners would seem to be the most obvious questions that candidates would be asked, although a discussion about X-rays is also fair game. Sometimes, the examiner may put all of them in front of you (X-ray/ultrasound/CT/MRI/bone scan images) and give you a choice to speak on any one of them. A candidate scoring 6 would start to run out of steam at 3 minutes or struggle if they are seriously probed about the topic in detail. A bit depends on the examiner themselves on how much they really do understand the subject in depth, but you are gambling a bit with this one.