The mammograms of another 1,000 women are being reviewed, as part of an investigation into the breast screening programme in north Cumbria.
It was suspended in July, after concerns were raised over data from women called for a second screening.
Sixteen women who had been given the all-clear were later found to have breast cancer and a report highlighted a failure to follow best practice.
It also called for further records to be examined to "provide reassurance".
The sample - 500 routine mammograms, and 500 from women who have previously had breast cancer, or have a family history of cancer - have not been involved in the assessment process.
The findings of this study will be published in due course.
Three radiologists involved in the programme are to receive more training, and when the service resumes it will be run by experts from Newcastle.