Medical imaging, like everything medical, nuclear, and military, has somewhat high barriers to entry due to legal requirements, eg getting sued b/c of the proverbial amputation of the wrong leg due to flipped display. Also, from my limited experience in the field, software for radiology workflows and archival, viewing workstations etc. are often expected as part of a deal for the imaging devices (X ray, MRT, etc.) themselves rather than as separate products.
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.
