What time frame, number of PSAs, and calculator do you use for calculating PSA doubling times?

I typically use only values of 0.10 ng/mL or greater, and at least 3 separate PSA values that are at least 3 weeks apart from each other. The greater the number of PSA values, the more accurate the PSADT calculation will be. I like to use the MSKCC calculator: Prostate Cancer Nomograms: PSA Doubling...