Senior consultants at Craigavon Area hospital have raised concerns about the safety of x-ray procedures.
In April 2010 a new system was introduced which meant 27% of all x-rays were not reviewed by a consultant radiologist.
In a letter dated May 2010, senior consultants said that "patient safety was being compromised".
The trust said it was satisfied x-rays were viewed by fully qualified staff but there was a back log of 2,500.
An unnamed consultant at the hospital told the Stephen Nolan show that he had serious concerns about missed diagnoses.
The consultant said he had heard of eight-to-10 cases involving cancer but the trust said they were aware of one.
In the letter to the Medical Director of the Southern Care and Social Health Trust, senior consultants called on the trust to address their concerns as a matter of priority.
They said they centred on the "inadequate reporting service" of x-rays.
"We believe, and have evidence in specific cases, that patient safety is being severely compromised."
The letter also states the consultants' view that all x-ray films should be reported by trained radiologists.
They added: "Any negligence claims arising from missed abnormalities on non-reported plain film x-rays may well be indefensible."
In a statement the trust said having been advised by clinical opinion, staff reporting x-rays are "sufficiently trained and expert in interpreting plain x-rays."
"The Trust Radiology Department prioritises work and effectively manages risk by ensuring that all high-risk images are seen and reported by a consultant radiologist.
It said: "The Trust has also recently entered into a contact with an independent sector provider used by the NHS to undertake the reading and reporting of a small number of plain film x-rays until a position can be reached with the Regional Board as to how the capacity gap (back log) can be addressed on a permanent basis."
Dean of Radiology and the Vice President of the Royal College of Radiologists, Dr Tony Nicholson said across the UK best practice is plain film x-rays should be viewed by a radiologist.
"Every image should be seen by a radiologist but the practicalities mean this is not always possible," he said.
"The UK has the lowest ratio of radiologists to the population and we have 43 per million but the USA have 100, France and Germany have 60.
Dr Nicholson said the overwhelming majority of x-rays should be reported by the radiologist in that department.
"In practice the sheer volume prevents this from happening," he added.
"I would not like to say it happened it a lot of cases, but some hospital trusts have specific arrangements with highly specialised clinicians or neurologists that they will interpret and record their own films in their expert field and refer them to a radiologist for a second viewing if necessary.
"These review must be recorded by by law, whether electronically or digitally, but I must stress this should be in a limited number of cases by prior agreement."
The Belfast Health Trust says in its hospitals the doctors who order X-rays personally review them and in some instances a review by a specialist radiologist is requested.