ETA after your additional info:
You should have included this in your original question.
Abdominal CTs are the ones that people are concerned about causing cancer. Head and spine, if the CTs were not all the way down the spine, are not so much to worry about. It's really about how many are done over a lifetime.
If your child would have had a brain injury or a spinal injury, would you be fussing about them having been taken? Just because your child was okay doesn't mean there wasn't a reason to do the scans. How would you know your child is okay if they hadn't done the tests?
Of course your child's future health is very important, but wouldn't you rather make sure that your child is okay NOW? Rather than worry about cancer years from now?
Original:
Give us more information. What were the CTs for? WHERE did they focus the CT? What do you mean, you weren't given the choice? You said that it would have been okay if your child had not had the scans done. You had to sign for them, so you DID have a choice.
Your post isn't making sense.