The work of a fourth British Columbia radiologist has been called into question over the handling of 3,000 CT scans, mammograms and X-rays at four hospitals.

The review is part of an investigation involving almost 7,000 CT scans handled by the four radiologists who practised at hospitals in Powell River, Dawson Creek, Langley and the Fraser Valley.

David Plug, a spokesman for the Fraser Health Authority, said Friday that the latest radiologist whose work has come under investigation held a provincial licence from the BC College of Physicians and Surgeons that required regular assessment of his practice by a supervising radiologist.

Plug said that at the end of the radiologist's first three months of practice at Ridge Meadows Hospital in Maple Ridge, a random selection of his reports was assessed, and a full review followed.

Out of 197 cases reviewed so far, there was a discrepancy in how nine of the scans were interpreted, Plug said.

However, the patients' course of treatment in those cases weren't altered because of the mistakes and they received the appropriate care, he said.

Due to the findings at that hospital, another 1,933 scans the radiologist interpreted at three other hospitals in 2008 and 2009 in the Fraser Valley will also be reviewed, Plug said.

While two of the four radiologists were trained outside Canada, the other two were not and had been practising in their communities for years.

None of the radiologists linked to any of the cases is working while the reviews are underway, according to the BC Patient Safety and Quality Council.

A review was already underway of CT scans that had been interpreted by an out-of-province radiologist who practised temporarily at Abbotsford Regional Hospital and Chilliwack General Hospital between mid-August and mid-September 2010.

The findings from that process found that out of 170 CT scans, 11 had significant discrepancies and one patient is getting more tests to determine if any treatments should be changed, Plug said.

The 11 patients all received their CT scans at Abbotsford Regional Hospital, and the health authority sent notification letters to all 170 patients or their families.

"We sincerely regret that a second set of concerns around the inaccuracy has arisen in our region," Plug said.

Health Minister Colin Hansen was not available for comment Friday.

Meanwhile, a parallel review of the incidents by Dr. Doug Cochrane, chairman of the BC Patient Safety and Quality Council, found that all 287 radiologists currently working in B.C. are properly licensed, but they need more peer review and opportunities to upgrade their skills.

Cochrane said that as part of his review, he will help the College of Physicians and Surgeons, the health authorities and the B.C. Society of Radiologists establish a peer review system.

"I'm also going to look into now, at this stage, the actual details around individuals and where did our system break, if in fact it did break at all in terms of finding the errors and so on."

He said that in about 10 out of 100 CT scans, two radiologists may come up with different interpretations.

But he said a misinterpretation may involve a radiologist seeing one lump in a patient's lung when there may in fact be two lumps that could suggest a diagnosis of cancer or pneumonia.

"One is going to significantly affect my life, the other is going to be curable."

Cochrane said the whole issue surfaced last month after family doctors questioned radiologists' reports.

"They detected that the reports didn't seem to make sense in light of what they knew about the patient," he said, adding the information wasn't consistent with a pattern of the disease and other information such as blood tests and physical exams.

Cochrane will also review all the known cases and how the various health authorities responded when they learned about them.