Supported/validated browsers for medical device/software?

I have been in software test for medical devices/software for the last five years, across three different companies. With my prior two organizations we formally validated our web-based software products only for the one or two most recent versions of Internet Explorer (at those times). Having our software work in Chrome or Firefox were nice-to-haves, but we did not communicate to our customers that we supported those browsers,  I'm soon to start work on a major release of an existing product, and the Project has decided to officially test/validate only Chrome, based on our current knowledge that the current release has known issues with IE. Seems to me we could be taking the easy way out, and not taking into consideration what our users use (often by policy). Apparently we don't currently have that information, though, I have brought it up that we should try to figure that out. 

Historically, hospitals/labs/medical offices/etc have - by policy - typically only employed IE for business use, but I know market share in this sector has been shifting to Chrome. But how much/fast? General browser usage, and even entrprise usage statistics are easy to come by, but I'm banging my head at this point trying to find information specific to healthcare/medical research. 

What are your experiences/thoughts on this?