Those are easier to regulate. People research how large of a radiation dose is appropriate for an x-ray, or how long certain parts/materials can sustain what kinds of loads, and they can use this information to come up with appropriate regulations.

It's much harder to come up with the same kind of concrete regulations for software security (i.e., device must deliver no more than X dosage to patient). We might have to settle for forcing companies to carry exploit insurance, and make it easy to sue for breaches.