I see now that there are instances of "portal chest x-ray", such as this:
https://www.researchgate.net/publication/320697715_A_case_re...However if you look on the x-ray shown on the diagram, it says "portable". So I this point, either "portal" or "bedside" would fit.
"Figure 6:Last portal chest x-ray of the patient showed progressive bilateral metastasis"
This next link deals with postoperative emergencies, where the text suggests the patient is already in bed and in a fairly critical condition:
"Postoperative emergencies [...]
Reassure the patient and sit them up. Give high flow oxygen. Some patients with obstructive airways disease will not tolerate 100% oxygen, but do not let this deter you from giving sick patients oxygen.w1 Quickly familiarise yourself with the history and examine your patient’s heart and lungs. Check pulse oximetry and consider sampling arterial blood gas. Obtain an urgent portal chest x ray film."
https://mafiadoc.com/postoperative-emergencies_59a501c21723d...