This book covers the basics quite well. It is a question based format if you like that.
Learning Radiology is both a book and a website. The book is pretty good all around for beginners.
The website is good but it has a confusing format that is not very user friendly. If you can get past that it has a ton of good information.
If you use Facebook, Learning Radiology puts up a Case of the Day through their facebook page which has links to their website with answers. Like and follow their page if you're interested.