Cmacinnes, you are understandably confused. A digital rectal examination (Dre) is nothing to do with a biopsy. The biopsy probably involved 10 samples being taken. The results will show in a Gleason score x+y, where each unknown is a number from one to five, giving a total of up to ten. Ten years ago my score was 4+5=9. I'm still going strong, so worry ye not! The scan is to determine how far the cancer has spread, if at all, outside the prostate area. That will determine the treatment options. It would be surprising with a PSA such as your Dad has, if surgery is offered as an option, but it may be. The key thing for you and he to remember is that prostate cancer survivors live for many years after diagnosis, as in my own example, and still live active and fu!filling lives.
My advice is to trust in your medical advisors, prepare well for meetings with them, lots of written questions and make a note of their answers, think about them and get back with further questions. The NHS cancer specialists are very good in my experience and very tolerant of "silly questions", so don't be shy.
Lots of people on this site have been where you and your Dad are going so ask away and we'll all try to help.