Hey!

it is a really complicated job as well as tough education. to become a nuclear medicine specialist  you need to spend most of your early 20s and 30s in education alone.

the process is like

1. get a bachelors degree (engineering or medical)
2. get your medical training (medical degree PG if you already have medical UG)
3. get some specialization degree in medicine (related to nuclear medicine specialist )
4. Do any internship or work some where. but this is also a learning phase.
5. Get licensed by Govt.

now you are a nuclear medicine specialist

i hope my answer helps you