I had my Pet/Ct last Friday and was told to avoid all exercise for the previous 24 hours. I'd call the center that does the scans - or your doctor to be sure. I'd probably re-schedule the appointment for therapy - just to be sure. You'd hate to have a spot show up that couldn't be determined if it were real or caused by physical activity of the area. I dont know if they show up differently on the scans or now - if the doctor who reads it can tell or not?