Squire's fundamentals is a good one. It seems long, but is very easy to read and covers the basics. I believe the author is Novelline. Radiology is a very big topic to cover in depth.
Squires is great. They just came out with a new edition this year. It takes you from the ground up and is written in an easy-to read-narrative style. Don't knock yourself out trying to read Brandt and Helms or anything. Stick to the basics. Good luck
-Hans