Radiation Question for Prostrate Cancer

My Dad has prostrate cancer and his psa is 7 1/2. The Dr. gave him one treatment of hormone therapy and now tells him that he has to have 36 treatments of radiation and to continue the hormone treatments once every 6 months for two years. The paper said not to take any Herbs while on radiation. I am wondering why he can't continue with his Oreganol and Pumpkinol that has been used for centuries to help with prostrate problems. My Mom is going to ask the Dr. tomorrow why he can't use herbs with radiation. I was hoping to post a message of what herbs to take to help with side effects with radiation. My Mom took radiation treatments several years ago and now she can't taste her food. I hope this doesn't happen to my dad. I also wonder if there is anything out there that would help my Mom to gain back her taste buds again. Any advise or help would be appreciated. Thanks, Donna