The Health Service Executive has confirmed it has conducted a review of thousands of x-rays and other scans relating to three locum radiologists and seven hospitals.
Several hundred patients have been recalled and one patient at Bantry General Hospital in Cork has been found to have a delayed cancer diagnosis.
The main hospitals concerned are Bantry General, Cavan Monaghan and Kerry General hospitals.
Other hospitals affected to a lesser extent are Our Lady of Lourdes in Drogheda, Wexford General, Roscommon and Connolly Hospital in Dublin.
At Bantry General 4,388 scans were reviewed covering the period from May to September 2013.
Fifty patients were recalled and one delayed diagnosis was identified.
The patient is alive and is being managed.
At Cavan-General Hospital 2,980 scans were reviewed and 62 patients recalled, with no serious adverse events reported.
At Kerry General Hospital, six patients were recalled and no harm events were reported.
The HSE said Our Lady of Lourdes Hospital Drogheda and Connolly Hospital are currently carrying out a “preliminary audit” over a short defined period of time, to determine and act on any possible patient safety concerns regarding x-rays and scans.
The HSE added the work is being undertaken to provide assurance to patients that their scans have been correctly assessed and reported.
In both instances the time period involved was four weeks in 2013.
The locum consultant radiologist also worked at Wexford General Hospital and Roscommon Hospitals for short periods of time.
Management at both hospitals said they are satisfied that no patient safety concerns were identified.
Some of the reviews are continuing and the period under examination goes back several years and the radiologists are not working in the HSE anymore.
A number of the radiologists worked in other hospitals for a short period and this is why the review involves more than the three main hospitals.
The problems came to light after concerns were raised by colleagues of the radiologists.
The HSE said it is in contact with all patients requiring recall for follow-up investigations.
It said anyone who has not been contacted by one of the hospitals or their GP has no cause for concern.
Minister for Health Leo Varadkar said that his information on the review is limited, but confirmed it relates to three locum consultants.
Speaking on RTÉ's News at One, he said that, regrettably, a cancer diagnosis was delayed in one case.
The Minister said that x-rays from all hospitals where the three consultants worked will be tracked and reviewed.
Minister Varadkar said that the central issue is quality assurance and control.