A lot of imaging equipment is very software driven these days so the big companies tend to look for those with PC and software experience as much as hardware. Also they can attract those from competitors and experienced guys from the forces so getting in can be very tough.
I would look at contacting the smaller players such as
Carestream,
Med Imaging and
Xograph. Also see if your local hospital has a medical physics or medical engineering department you can approach.
Is there a reason why you are looking at medical imaging for work? It does not pay any premium and recent changes to 7 day working have not helped. I talked to a guy servicing a car park ticket machine and he was earning a lot more than most medical imaging engineers I know! He also has all the spare parts in his car (better than most provided by the medical companies) so had less stress!
