You are correct. My oncologist responded to me that if a patient is tested with a standard PSA test and the results are < 0.1, it is considered undetectable. My oncologist and urologist started using ultrasensitive PSA tests after my RP, so my initial post surgery PSA of 0.03 was not considered undetectable. He also stated that if a PSA remains below 0.1, a BCR of 0.2 never occurs, so the tests wind up at the same point in terms of next treatment set points.