Imaging orders often have a "question to be answered" in addition to the procedure to be performed. For example a chest X-ray order may include a request to "rule out pneumothorax."

I don't believe that coded values are used to ask these questions.

It may be that the existing reason or note fields are sufficient for this purpose (in which case it would be nice to see some additional guidance highlighting this use), a new field or standard extension may be needed.