ionizing radiation

Question is in the title. There are a lot of threads on the damaging effects of xrays, but how bad is it really if it happens once and the rest of your lifestyle is good? Talking about the entire spine here

Let me preface this before anything, that I never used to believe in this type of effect causing major damage to people...but let's just say I have felt the exact effects and I notice EXACTLY when I am getting hit with something, major migraine, fatigue, burning sensations etc. My question is...

My job wants me to do a Chest X-ray and I really want to avoid it for obvious peatarian reasons. Unfortunately its mandatory by law to get a chest X-ray when finding work where I live. I think the reason is that they're worried about people having tuberculosis. I'm trying to weasel out of it...