XRs are a tool and your ability to use that tool depends on the amount of time you actually use it. Yes there are radiologists out in the world that are specifically trained to look at and interpret imaging studies but the average physician can also do the same. When you are on your IM rotation you will be looking at chest films all the time and in most cases will not have the luxury of waiting for a final read before your create and implement a care plan. I am currently working in a primary care sports medicine fellowship and we probably order nearly 60-70 XRs per day, reading them all ourselves. In most cases our reads are better than some of the radiologists unless it happens to be an MSK radiologists that sees our films. You also have to remember that in some places the FM doc is all there is for that area, they have to be able to do a little of everything from primary care to peds to OB to hospital medicine to radiology. As a word of advice you should learn to ALWAYS read and interpret your own films, let the radiologist report tell you if you are correct or not.