[Insert "let me laugh even harder" meme here]

That would be actual malpractice in either case.

LLMs have a history of fabricating laws and precedents when acting as a lawyer. Any advice from the LLM would likely be worse than just assuming something sensible, as that is more likely to reflect what the law is than what the LLM hallucinates it to be. Medicine is in many ways similar.

As for your suggestion to be capture and analyze ultrasounds and X-rays en-mass, that would be malpractice even if it were performed by an actual Doctor instead of an AI. We don't know the base rate of many benign conditions, except that they are always higher than we expect. The additional images are highly likely to show conditions that could be either benign or dangerous, and additional procedures (such as biopsies) would be needed to determine which it is. This would create additional anxiety in patients from the possible diagnosis and further pain and possible complications from the additional procedures.

While you could argue for taking these images and not acting on them, you would either tell the patients the results and leave them worried about what the discovered masses are (so they likely will have the procedures anyway) or you won't tell them (which has ethical implications). Good luck getting that past the institutional review board.