The union representing salaried doctors said it had become a common occurrence at the hospital, with a similar situation arising a few weeks ago.

In an email sent to staff on Tuesday, Director of Medical Imaging Mark Duggan said due to unplanned leave, from August 20 to 24 inpatient reports would have to be processed by external provider Everlight.

Patients will have their images electronically sent to the provider, who reads the images and provides a specialist report to the patient's treating team.

Salaried Medical Officers Federation secretary Stephen Crook said it meant doctors making a report from the scans would be doing so off-site and would not have the benefit of seeing the patient or consulting with other doctors in person.

He said while it was common practice in regional hospitals, it was not so for tertiary hospitals.

Mr Crook said it flew in the face of ACT Health's stated desire to focus on patient centred care.

“A lot of the doctors are unhappy because it means they can’t talk over a scan or a patient in person,” he said.

“They’re talking over the phone and talking about an image rather than a patient.

"It's not good clinical practice for a tertiary hospital."

A spokeswoman for ACT Health said an off-site radiology service was a recognised strategy in many hospitals, particularly in regional areas.

"This is an important person-centred approach, because patients and their treating teams want to know their results as soon as possible. The use of an off-site radiology service supports this approach," she said.

"All other avenues for on-site reporting are used first, but once these are exhausted, images are sent off-site to ensure patients get their results as quickly as possible. Steps like this are undertaken as required to manage sick leave or after hours work.

"Unplanned leave unfortunately cannot be avoided. This process ensures Canberra Hospital has arrangements in place to ensure the continuity of the service at all times."

The spokeswoman said the recruitment for two new radiologists had begun.

She said there had been significant improvements to the department that had led to decreased waiting times for patients.

It comes after a report which found the department was at risk of losing its teaching accreditation

The Royal Australian and New Zealand College of Radiologists interim accreditation report from March said Canberra Hospital's radiology department was at risk of losing its teaching accreditation with its rating dropping from an A rating to a D.

The report said there had been significant unplanned leave in 2017/18 that was affecting training and patient care.

Internal documents seen by The Canberra Times show hospital bosses knew registrars had serious concerns about their training at least a year before the report was created, but failed to address them.