Do they use PET to detect cancer?

My German friend who is nurse told me PET was the most effective way to detect cancer, better than MRI. She said it was expensive and not covered by health insurance. I wonder if they do PET in Australia.

Doctors says my breasts are dense and difficult to see. They even seem to think bilateral mastectomy is the way to go when I am over 50 and no lymphnode involved. Can PET help to find out more?