Hello, 

As per your question, i would say that medical physics is a msc degree but not a subject of msc physics. 

Basically, the course MSC PHYSICS is designed for studying diagnosis of human disease, planning and development of equipment for treatments. Students develop understanding of radiation physics, principles of radiation and its kinds used in medical fields.

So those who have interest in dealing with the practical part of human treatment using machines and all, take up this course to find out more details on how to work on it. 

People interested opt for a branch named msc medical physics which is a 2 year pg course after which they probably go for medical machinary technical lines. 

Good luck.