I am 30 and used to worry a lot about cancer risks. I still do occasionally. I've had a number of tests - Barium Swallow, CT Scan, X-rays. I imagine those are all great multiples of radiation/cancer risk than the angiography.
Ultimately it is your decision. But you are already running a number of cancer risks that you are more or less unaware of, mainly due to genetics. Diet and habits also play a big role. So I'd just like to let you feel a bit better by letting you know that all of these risks are flying around you all of the time, and most of them you aren't even aware of. Well, maybe that doesn't make you feel better :)
But you get my drift. If you need a medical test, I'd say get it.
A few years ago I was all about taking no risks to my health or increasing my cancer risk in any way. Now I have learned that life doesn't work that way. Everyone has to accept risks now and then, because in life, they are unavoidable...