If you are interested in high income, doing solo practice in rural areas (no managed care) is the way to go. You can do approximately 100 studies a day (no angio or interventional needed), you can expect to earn about $800k after billing costs. No vacation, of course. If you want to take vacation, a week off = $10 to 12k to hire locums.
Also, you are on call 24/7. If you don't want call, you can outsource call for $1000/wk for preliminary reads (CT/US etc).
I know a guy who made $1.2M (before costs for vacation/call etc) last year in the Midwest. He did angio, plus he did more like 130 studies/day (the maximum workload any rad might be able to handle).