I already have a degree in ultrasound and I want to go into Nuclear Medicine but I don’t know where to start.?

I have researched it online, and I think I qualify for a 1 year program, I just don’t know if there really is such a thing. I also heard that you can train in a hospital, but I want to go into an accredited program, is this possible?

How long will a Nuclear Medicine program take for a person that is already registered as a x ray tech?