One more thing, I don't want to worry you more about the radiation! If my daughter had to have a head CT scan, I would remind them about using a ped dose, but wouldn't worry beyond that. When they use the right dose, it is really a very, very low dose. I just thought the info may help, if you were interested.
Re: Andrewsgal
I just wanted to tell you that the same thing happened to my DD#2. I was so scared! At her 9 month visit, her head size went from below 50% to >97%. We had an U/S and a neuro visit, and everything was fine. They took one look at my husband (and his big head!) and blamed it on genetics. Right now, she is 14months, and wearing a 3T-5T hat!
Hugs and prayers that everything is ok. I know how scary it is!