Reach in any field is great if you have an interest in that specialty. Not many Indian medical graduates believe in this, but it's true. Speaking specifically about radio diagnosis, the scope is good.
Almost all other specialties refer patients to the radiodiagnosis department these days to be more firm in diagnosis. So many doctors in private settings cut the practice. They earn a large amount by doing so. But creating your own radiodiagnostic center is a huge investment.
In government settings, your salary will be the same as any other resident or consultant; Regardless of the department in which you are working.
As you have specifically asked about the salary aspect, I would like to tell you that the salary of a doctor in India depends on many factors other than the chosen specialty. The most important among them is the location. In your case, if you open your center in a third or a subway city, you will face a fierce competition of those already established. If you go to a village, you will not gain anything since there will be no competent doctor who will refer you to patients who need CT / MRI. The maximum you will get is it can be ultrasound for pregnancy.
The best will be a two-tiered city or a small city or a city close to a large city where you will be only one or one of two or three radiodiagnostics.