If you test positive for the skin test but negative with x-rays it means that you have latent TB, this is actually quite a popular condition. Anyone who has ever been exposed to someone with TB will test positive on the skin test (your body has produced anti bodies), this is true of many health care professionals as well as anyone who has been vaccinated against TB. You are not contagious nor pose any threat to public health, however if you tell the recruiter about the condition, you may have a difficult time getting a placement however. The TB test that they do upon arrival is the chest x rays. You should be fine.