Dad has his mapping on Friday for salvage radiation 16 January. His persistent PSA post surgery in June was 0.08 ( from 14) and in December 0.17. In December he started ADT in advance of salvage radiation for 6 months. He will have 33 sessions at 66gy. I question 66gy believing that higher dosages are more effective but the radiologist was adamant that this was optimum for his situation without unnecessary radiation. His scans were good with rectum and bladder perfect so they considered this "easy mapping". Should I be further challenging the dosage for 68gy/70gy in your opinion or should I accept their professional opinion as the experts in their field in a top London hospital?