They have high barriers to "marketing." But if you find a radiologist who wants to work with you, using your software, that's their discretion, as long as you don't make "claims" about its efficacy for use. The way to Cover Your Assets is to have them use your software first, then REDO the read on another system marketed for the job. If they come up with a different set of results, you have work to do.
Source: 14 years in medical imaging.