My local hospital's were in the position of being 'fined' a few years ago, because they were not meeting targets for some procedures.
The result of that, was one of the hospital's obtain the services of an outside company qualified to do scans, who rigged up a couple of juggernaut's and other specialist equipment in the car park on Sunday's. I attended one such session, and other patient's waiting with me all thought the idea was superb. And it was. No hassle or rushing etc, only problem was public service transport for those without vehicles, so it was a case that some had to order a taxi.
Ultrasound scans were no problem, plenty of hospital staff available for that.
True, there is quite a lot of very expensive equipment going idle at weekends, mainly due to either staff shortages, people not wanting to work on Sunday's, or funding arrangements.