Hi LMD and welcome.
I am sorry that you are feeling so worried about
the possibilities that are uncertain to you in regards to your tests.
Please know that you have had a reasonable amount of exposure, and what is considered safe in the medical community...with the CT and CTA.
Try not to worry about
the 'what ifs' and consult with a radiologist if you truly can't shake the anxiety in this regards. They will likely be able to put your mind at ease...and you will get much more definitive information than you will from google searching!
We have some good tools in our Resources here (see link below) that may help you with these worries...
https://www.healingwell.com/community/default.aspx?f=9&m=104206
The therapy worksheet downloads are especially helpful in dealing with persistent thoughts/worries.
The general stress relieving exercises are great as well.
Keep talking with us if you find it helpful. We understand how it feels to be frightened...and are here to encourage you anytime.:)
Scaredy Cat