Well.....
The doctor then wrote on the I-693 that I was found negative on my skin-test, even though I just took X-ray.
He also wrote that I took a couple of shots and that I was current with all the others (of course I took no shots whatsoever).
It really depends on the doctor, but I remember reading on some USCIS form (I guess the I-693 instructions) that you could really choose between skin test and X-ray.
X-ray is more accurate and enough to tell if you have tubercolosis, but some people don't wanna do it because of its radiations....