I should have noted that I was trying to help out the original poster (my apologies) but since you asked...
You stated it doesn't say anything about it (Chest X-rays). So I thought...hmm, maybe it doesn't. However, the link has, like I said, more info than you need. I used the site's own search link and typed X Ray and found several reasons why they do chest X rays. Try it. Shoot, I even searched for pectus excavatum and found out that information as well. Try harder next time.
And as for the link I posted earlier, it addresses supplements as well.