That's not necessarily a bad thing!
In our industry, the idea of something using XP is ridiculous. Applying our experience to the medical field is a bad idea!
It's an appliance. It doesn't really matter what OS it runs as long as its stable and certified to do. It spits out imagery which you can then process and view on any compatible device - often a reasonably modern computer running some sort of health informatics platform.
For what it's worth, the "XP" OS is often licensed and supported for well longer than a consumer SKU. IIRC microsoft provided support and security updates for embedded/appliance applications until 2019!
These devices are often not openly networked, or if they are, they are through some sort of gateway that's appropriately locked down and updated.