Had 3 ct scans over the last 15 mons after an infection from a dental procedure. today i was told i will most likely get brain cancer- is it true?

No: risk of brain cancer after exposure to this amount of radiation is relatively low. It is far more important to be sure the infection has been treated successfully.

Run: Run, as far away as you can, from whoever gave you the misinformation that properly administered medical tests cause brain cancer. Also, I doubt that your dental procedure caused infection. More probably you had a dental infection that was beyond the scope of the procedure to cure. You had appropriate testing to asses both the extent of the infection and the treatment effectiveness.