30 year old female having sever anxiety over my first and only ct scan for a rib injury, terrified one scan is going to give me cancer in a few years?

Unlikely: The chances of this happening are extremely low. discuss this with your doctor and he may be able to calm your fears. To quote from a 2013 article in Scientific American “The jury is still out on whether there is a small cancer risk,” says Donald Frush, chief of pediatric radiology at Duke University Medical Center.

The theoretical risk: of any procedure or treatment should always be weighed against the benefit. In your case, the theoretical risk of developing a radiation induced cancer from one chest CT is slight, about 0.09% over your baseline risk. To put that in perspective, you have about a 10x higher lifetime risk of dying in a motor vehicle accident. Yet few people worry very much about getting in their car.