Thanks for your question on Health Care Magic.
I can understand your situation and problem.
PET scan is having highest radiation exposure.
CT scan is also having higher radiation but less than PET scan.
Permissible PET scan exposure is once in six months.
And for CT scan it and once in two months.
Anything more than this will cause
radiation injury.
To prevent radiation injury you should follow these steps.
1. Drink plenty of fluids orally and keep yourself hydrated atleast 2-3 prior to scan.
2. Avoid Nephro toxic drugs atleast 1 week prior to scan. Dyes used in these scans can cause renal damage. So better to prevent other drugs causing renal damage.
3. Start N acetyl
cysteine (NAC) 1week prior to scan and continue it for 1 week more. NAC is antioxidant in nature and helps in prevention of oxidative damage done by radiation.
Hope I have solved your query.
I will be happy to help you further. Wish you good
healt. Thanks.