[SABRMnLgs]

Someone wrote that "CT scans are replacing x-rays". That is incorrect and it will never happen. Call it overkill. For a number of reasons. I won't get into the medical aspect of it, it's boring and I could go on for paragraphs.
But things are done in a certain order for a reason.

Routinely, if there is a problem x-rays are done first. Then on to a CAT scan, or an MRI, Thermonuclear, etc.

Example, after my wife fell in Wal-Mart, she had radiographs of her knees. When the radiographs showed a possibility of a fracture or an ACL/PCL tear she had the MRI. Why? Because you are unable to see these things (soft tissue) on a radiograph.

If you have an obvious fracture, then an x-ray is possbly all you will need.

And the other reason is cost and usage. An x-ray unit wether portable or staionary, while expensive, still costs a lot less to purchase and maintain than other genres of medical photographic equipment.

Lastly, the only unit viable enough to be used portably is an x-ray unit. There is just no CT, MRI, or Thermonuclear unit that you can roll to a patient's room, to a nursing home or a private residence.