You also need to balance what happens if you do have the scan too.

Over-testing leads to over-diagnosis, and that can be harmful.

Very few modern insurance plans pay per procedure and that will be done away with entirely as time goes on. Typically physicians are paid a flat rate per patient or a flat rate per diagnosis with a complexity multiplier. This creates an incentive to NOT perform imaging unless it's necessary.

In what country? The US is still mostly per per procedure. There are codes for procedures and for diagnoses and they both get factored into the bill.

Take a look at DRGs. In the US they were first used for payments in the Medicare system but they have expanded outside that program over the years:

https://en.wikipedia.org/wiki/Diagnosis-related_group