An independent review will be held following delays in the diagnosis of four cancer patients in Londonderry.
Some at Altnagelvin Hospital had to wait up to 10 months because of a backlog in the reporting of around 18,500 X-rays.
Health Minister Michael McGimpsey said the Regulation and Quality Improvement Authority (RQIA) would be asked to review reporting arrangements for radiological investigation across Northern Ireland.
"Following the delays in reporting of X-rays at Altnagelvin, I have decided to commission the RQIA to review the handling and reporting of radiological requests in all health and social care trusts in Northern Ireland," he said.
"The public must have the confidence in our health and social care services. I want to reassure them that I will do all that I can to ensure that we have the systems in place to prevent something like this happening again."
The chief executive of the Western Health Trust Elaine Way has said she will not resign over the X-ray backlog at Altnagelvin.
Ms Way admitted a backlog of X-rays at the hospital had built up for two years before it came to the attention of the trust.
Stormont's health committee has been told a backlog of X-rays at Altnagelvin Hospital was building up for two years before the Western Trust realised there was a "serious problem".
Ms Way said staffing issues at the hospital, prompted by the retirement of two senior radiologists in 2008, led to the backlog.
She admitted she did not realise the problem was so severe for another two years, when she was notified that a patient had been diagnosed with cancer that had not been detected.