The conundrum of cut film
There is no way of avoiding the fact that the viva exam is presented on films, with selected slices only and no ability to scroll. It seems discordant from the everyday practice of reporting, since we are so used to reading in a PACS format on a computer screen. Having to read a cross-sectional imaging case on film - under pressure - can bring even a good candidate undone. For me, the abdominal imaging viva was my hardest station - trying to follow bowel on film with 20 images to a sheet is tough. I know that a lot of other current and past candidates felt the same.
To be honest though, I think there are certain advantages to having the exam film based. There is a certain tradition and connection to the art of radiology. It also gives you the valuable skill of actually being able to read printed film efficiently, which you will no doubt be faced with in multidisciplinary team meetings or when reviewing external prior imaging.
Regardless of what your opinion is, however, there is no escaping that the exam is on film - and for the moment this isn't changing. This means that to pass the stations you need to develop your confidence with reading film under stress.
Being able to follow bowel is an obvious example, however the skill of being able to read film is equally applicable outside of the abdominal viva. As my subspecialty area of interest is chest radiology, I have a collection of films that reflects this. One of the greatest stumbling blocks I see candidates encounter is looking for lymphadenopathy in the mediastinum, and even good candidates often don't have their eye in to be able to accurately assess the nodal stations of the thorax. This is very important in several chest set-pieces, including lung malignancy cases, interstitial lung disease and nodules cases (e.g. sarcoidosis or tuberculosis).
The only way to become good at reading film is to practice. There is absolutely no way around it. A quote I love, which has been used to describe the Roman Army at the height of their power, is "Their drills were unbloody battles and their battles were bloody drills". Essentially this means that when they practiced, the exercises were as closely reminiscent of the real event as possible. When they eventually marched into battle they were as well prepared for what followed as they possibly could be.
I followed this in my viva practice to the letter, and I'm, sure I will repeat myself over and over to this effect. It is in your best interest as a candidate to prepare in situations as close to the actual exam as often as possible, whether that means stimulating stress, the difficulty of the cases or the physical presentation of the cases.
I worked through our film library with my colleagues steadily and regularly. We were reading cut film most days of the week, with a mixture of plain x-rays, CT, ultrasound and MRI. It was hard at first but eventually I started to almost get frustrated with having to present practice vivas on the PACS as I didn't have all the information in front of me at once.
As a team, we tried to know which consultants had sets of films hidden in their offices that we hadn't seen yet - making a point of approaching them to see if they had time to share. If you are lucky enough to work with a consultant who has been an examiner, they will no doubt have a wealth of films and exam level cases which they might share with you if you are lucky enough.
As crunch time approached, I started printing films of cases and concepts that I was struggling with. I didn't collect DICOMs of my interesting cases, I kept films. An advantage was that I could have good quality practice at home (I bought a light box off Gumtree from a chiropractor) and I would have films for prosperity to maybe show candidates in the future.
It goes without saying that you should still work with DICOMs of interesting and challenging cases if they are available - it is all part of getting the broad exposure to as many studies as possible. In fact, in the lead up to film writing working with DICOMs is probably preferable. What you should strive for is balance in your approach. Remember that developing the reading technique is as important as the facts you learn. After all, you can have the most in depth knowledge of medical imaging of all the candidates but unless you can present that knowledge in a clear, structured and synthesised manner the examiner cannot reward you.