well they had to study general physics and some more advanced stuff as well to be called a medical physicist so I should think they would know something about. Their specialty wouldn't be astrophysics but they could read the papers and get some understanding beyond what a layperson might.
lol, seriously? Medical Physics is just another physics subspecialty. We all get General Physics, Light & Atomic Physics, Solid State Physics, Nuclear Physics, E&M, etc., as well as math Diff Eq, Ab Alg., Lin. Alg, etc. Now, as far as the "universe" is concerned, no we don't have any intense study of space, astro physics, etc. Our undergraduate degree is a standard physics major. Graduate school is a little more rehash of the undergraduate material at a little higher level, add the Anatomy & Physiology, accelerator physics (x-ray, proton, electron, HCP, etc.), radiation detection, nuclear medicine (radiopharm generation, safety, apps), Imaging using x-ray/ultrasound/MRI/etc, clinical oncology, beam modeling, etc. In short, there isn't a "just know only health". In my day, we also did NE, nuclear fuel cycles, HP, etc.
This is an interesting although perhaps oddly worded question.
To become a medical physicist you (generally) start out with a degree in physics. Then you go to graduate school and specialize in medical physics where other students would specialize in the other fields like astrophysics or condensed matter physics. Different schools have different curricula. To meet professional accreditation requirements each program will cover specific (and often very practical) aspects of radiation physics, treatment planning, imaging (diagnostic x-ray, ultrasound, MRI, etc), computational methods, radiation biology, nuclear medicine, radiation protection and anatomy & physiology. Some programs will meet the bare minimum required for professional certification. Others will, in addition, require their students to pass the same comprehensive physics exam other physics students get and/or take similar core courses. In my progam I had to get through Jackson and Sakurai just like everyone else.
Clinical medical physicists can become, professionally, like a dentist or engineer - using very detailed, practical knowledge to solve problems that no other profession can. Clinical physicists will rarely if ever be involved in research pushing the boundaries of physics itself. Rather their research focuses on more practical problems.
On the other hand, there is an academic aspect to medical physics. Still the research tends to be more like solving engineering problems than pushing the boundaries of physics. (You are not, for example, going to discover a Higgs boson doing experiments with a medical linear accelerator.) But the research can still be quite technically involved. For some examples of current research in the field I would recommend browsing through the journals:
- Medical Physics
- Physics in Medicine and Biology
- Journal of Applied Clinical Medical Physics
- International Journal of Radiation Oncology, Biology Physics