Good luck to him.
To be honest the radio itself isn't particularly tough, the challenge is having your body in the state they want it - for my trust, bladder half full and rectum empty. I did my best to follow their instructions but there was a fair amount of unpredictability, partly because it obviously depended on the previous patients whether my machine slot came exactly when listed.
There was a definite comeraderie in the waiting area, and while there were patients for multiple types of cancer the prostate boys got to know each other and we all had the similar embarrassing experiences of being rejected while we drank more water, or more difficultly tried to wee just the right amount to suit. (I was lucky not to ever be rejected for a too full rectum, but some had to go and have a mini-enema).
In some ways though it was a breeze for the first three weeks, I cycled to the appointments (hilly 5 mile route), did normal things, and hosted a big family weekend-long party for my 70th birthday. But by the last week I was running out of energy and preferred to drive, and the few weeks following I was similarly drained and needed to collapse into bed really early each day. It didn't last too long though, not much more than a month later my wife and I went on holiday to the Alps and did some reasonable (though slightly cautious) walks.