Prince Edward Island's Health Department announced Monday it will review tests done by a radiologist over a four-month period ending in April after a preliminary audit showed an unacceptable error rate in the doctor's work.

About 4,500 patients who had regular x-rays, MRIs, CT scans or ultra-sounds are affected and a total of 5,700 images will be re-evaluated.

"Patient safety and quality care are our top priorities and that's why this review is happening," Health Minister Doug Currie said in a statement.

"We know exactly which images were read by the radiologist over the past four months and all of them will be evaluated again to ensure amended reports are sent to attending or referring physicians if necessary."

The department said it's standard practice for radiologists to monitor each other's diagnostic imaging tests.

Three tests were reviewed earlier this month by the radiologist's colleagues and amended reports had to be issued, the department said in a news release.

A sample audit was then carried out on 10 per cent of the diagnostic imaging tests done by the doctor and it showed "an unacceptable error rate," which led to the full review.

The sample audit was done April 11-23 and it showed an error rate of between eight and 19 per cent, depending on the type of test. The average error rate for all tests was 12 per cent, the Health Department said.

It said there are no national standards on acceptable error rates and medical literature varies widely on the subject, with error rates ranging from two to 20 per cent considered acceptable.

On the Island, the department said, the province strives for an error rate of less than five per cent in its quality audits.

"The results of the evaluation so far show that the majority of cases were not of a serious nature," the department said.

It said the doctor is "very well qualified, has as an excellent career track record and has been extremely co-operative in this process."

The doctor, who began work on the Island last year, agreed to a leave of absence while the review takes place. The review is expected to be completed in the next few weeks.

It's just the latest in a series of potentially damaging reviews in medical expertise and laboratory work in Atlantic Canada.

In St. John's, N.L., a class-action lawsuit is moving forward and a judicial inquiry is underway into flawed breast cancer test results given to more than 400 patients.

In addition, radiologist Dr. Fred Kasirye quit the Newfoundland hospital where he was employed last year after a review of nearly 3,800 patient records under his purview found that he missed problems, such as tumours, cases of pneumonia and broken bones.

In New Brunswick, a judicial inquiry is getting down to work in the case of Miramichi pathologist, Dr. Rajgopal Menon. About 24,000 pathology tests performed by Menon are being reviewed after an audit of his work showed incomplete or misdiagnosed results.

The P.E.I. government is describing its review as "precautionary," stressing that there is more to diagnosing a patient than radiology tests.

"It is very important to remember that diagnostic imaging tests are only a part of a patient's care and treatment," said Dr. Colin Foley, provincial medical director for diagnostic imaging.

"Patients typically go through a variety of tests leading up to their diagnoses and have more than one health care professional collaborating in the overall care."