Re: Imagine..
Well, perhaps. But, I'm under the impression that dosage is exponential. So, with 350msv is between 2^3 and 2^4 times 30msv. I don't think it's that much of a difference. But, don't quote me; I'm no radiologist.
Also, I think they try to limit CT scans to once a year, as they do produce more radiation than regular x-ray.