Each reader had a 4-h tutorial with one author (KK) explaining the AWBU reading station operation. The readers reviewed and discussed approximately 12 AWBUs with known cancers, not part of the test set. They were not in the test set because either palpable findings were present or there were no concurrent mammograms. Nothing concerning the study was discussed, other than the use of the data form (Appendix A) and the number of cases to be reviewed.