When i was a child i had many dentist x-rays and at 16 i had two or three head cat scans within a month of each other i'm i goin too get brain cancer?

Little risk: Especially in the last 20 years, dental x-rays have used infinitesimal amounts of radiation. The exposure from CT scans is greater but it's still too low to measure in any population-based study. What you've read is based on data from atom-bomb survivors extrapolated on the assumption of a linear relationship, which makes no sense biologically. Stop worrying about this stuff.