When they say don't drink caffeine believe them. I had the SBRT 5 proton treatment at Mayo Phoenix. I had my coffee waiting for me in the car for the drive home of about 35 minutes after my first session. Drank my mug and finished the pot when I got home no problem. Second treatment two days later and the same thing. Third treatment on Friday two days after that and my bladder said to me "YOU IDIOT". peeing every 15 minutes for hours and hours till the coffee wore off. Last two treatments the next week were WATER ONLY. I didn't have my morning coffee till my bladder and prostate calmed down. Two years later no problem drinking the whole pot and no bowel trouble, but I did have the SpaceOar gel.