Thanks for the update @Reciprocity. It sounds like you have a good team and a smart game-plan. Everyone here on the Train is pulling for you, too.
I agree with the suggestion about a driver for your last couple of sessions. When I had radiation, my fatigue was definitely cumulative, and I had to ease up on my schedule for a while.
They may ask you to hold your breath for periods of time during treatments. It may help to casually practice that a bit beforehand. I found a couple of well-paced songs to replay in my mind, and that helped a lot. Weirdly, The Wellerman sea chanty was the perfect tempo, LOL.
You got this!!