I did head ct scan 10 years ago and thoracic spine mri 1.5 years ago and a chest x-ray 6 months ago i'm worry about the amount of radiations?

Minimal: MRI does not use x-ray radiation, but instead uses a magnetic field. A single chest x-ray is very minimal. A CT scan of the head will give you about 20 times as much radiation as a chest x-ray, but this is still felt to be less than the background radiation you receive in 1 year just from being outdoors. It's good for you to limit your radiation exposure,but yours is minimal, I wouldn't worry