I have to confess I'd never heard of Jack Hand(e)y before, and had to Google him. Wikipedia says he's a "humorist", so I'm guessing it means "humour" in the classical medicine sense of bile and phlegm.
"Medical" and "open source" are very uncomfortable concepts for me, when combined. I'd be very surprised any manufacturer would warranty such equipment, and I don't know how you'd get any kind of compliance certification. I'm pretty sure Atmel distance themselves from medical uses of their processors.