The President of the Irish Medical Organisation has said she believes few people will be adversely affected by the glitch in the Health Service Executive's computer systems.
The HSE has said it is working to establish how many patients may need to have their medical tests redone after the flaw was identified in its systems.
The glitch in the national medical imaging storage system was spotted about a week ago in a provincial hospital.
Thousands of X-rays and other scans since 2011 may be affected.
A HSE investigation is under way to establish the extent of the issue.
When the scans were archived, the "less than" symbol was omitted. So instead of the system saying, for example, the narrowing of an artery was less than 50%, it wrongly said the narrowing was 50%.
Some patients may have received unnecessary treatment as a result of incorrect information on the HSE's computer system for storing scans. Others may need to have their medical tests redone.
Dr Colm Henry, the HSE's national clinical adviser for acute hospitals, said patient safety was a priority.
Patients affected by the HSE computer system error will be contacted through their hospitals and clinicians if action needed – Dr Colm Henry pic.twitter.com/JaOVkkuRus
— Morning Ireland (@morningireland) August 3, 2017
He said they will contact patients if any additional treatment is required.
Speaking on RTÉ's Drivetime, Dr Ann Hogan of the IMO said a "single test is never the deciding factor when a patient is treated."
Dr Hogan said a combination of tests, together with a multidisciplinary team review, would form a decision on whether to proceed with most treatments.
She said this flaw in the computer system serves as a reminder that technology can never be fully relied upon.
A statement issued on behalf of South/South West Hospital Group said: "Cork University Hospital wishes to advise patients, who have been imaged and treated in the CUH group, that they are not affected by the National Integrated Medical Imaging System problem."
Dr Chris Luke, consultant in emergency medicine at Cork University Hospital, has said that it is unlikely that patients would be treated on the basis of one erroneous test report.
He added that it would be potentially serious if patients were overtreated due to false positive results.
He expects that such things would be picked up by multidisciplinary teams, where doctors confer on a range of tests and checks relating to patients.
He said that doctors have an obligation to verify tests, repeat checks and to look at all of the patient's previous results.
In a statement, the HSE said it had identified an issue involving imaging examinations reports, which are generated as part of the National Integrated Medical Imaging System (NIMIS).
It said: "The issue identified is in relation to the 'less than' symbol (<) being recorded in the examination report on the PACs [picture archiving communication system] component.
"Where the (<) symbol is used on a report and when that report is viewed electronically within the PACS, the symbol has been omitted and is not visible."
However, the HSE said the majority of reports are either viewed on paper or electronically within the NIMIS or Radiology Information System - neither of which are affected by the symbol issue.
Reports sent electronically to GP practices are not affected by this issue, it added.
The HSE said all hospitals and radiology departments operating the NIMIS have been notified.
The executive has convened a serious incident management team to assess the risk to patients as a result of this flaw.
It is examining a representative sample of 10% of the affected scans to see if a further clinical review is required.
