B.C. health officials are contacting thousands of patients after it was found that two unqualified radiologists performed their scans.
Officials say cancer may have been overlooked in about a half-dozen patients.
The Ministry of Health says the unidentified pair lacked "either the appropriate credentials or experience" to properly assess the results of both ultrasounds and CT scans.
B.C. Health Services Minister Colin Hansen announced there will be an independent investigation in the matter.
"I want to apologize for the stress and anxiety this may cause," Hansen said of the situation.
The ministry is beginning its investigation with 30-day review to make sure all radiologists in B.C. have the proper credentials.
Last October, it was found a health worker, who had been performing the tests since 2002, was not capable of performing them correctly.
That health-care worker had looked at about 2300 obstetrical ultrasounds and almost 900 CT scans.
Officials believe of those 3,400 tests, only 40 had some type of discrepancy.
There were similar issues with a health worker in Abbotsford, but only 170 tests are in question there.
Neither of the health-care workers is currently working in B.C.
With a report from CTV's Rob Brown
