I had 15 radiation treatments three years ago. I'll try and synthesize what I learned in the hopes that it will be useful.
1. I was offered tattooed dots as part of the set-up. I declined, and that was no problem--the techs just marked with a sharpie.
2. I was given a robe and changing room, but on the second day I was told I could just wear a button down short and no bra. That worked for me. Find out your options and what works best for you.
3. I was given various creams. All of them worked well. Just slather it on, but be clean for the radiation. I didn't burn at all. You may get lots of cream suggestions here. In my experience they all worked well if used!
4. My mood was bad going in--I felt tense and exhausted just thinking about it. I set up a reward system. I went plant shopping at the near-by grocery store as it was spring a few times a week, and had a fancy caffeinated drink every other day or so. I told my husband I needed to hear live music once a week--and he got us tickets. You might not love caffeine and Mozart as I do, but reward yourself with things you care about.
5. I was tired during, but feel that was partially emotional. You should get a weekly meeting with the radiation oncologist, and that is helpful. My white cells were somewhat low towards the end, but bounced back. I kept to my usual exercise routine--and had to get all those plants in the garden! This helped.
6. At the end I took my husband on a bucket list trip because he turned 70. I took it easy on the trip, but we were both surprised that my energy was quite good.
7. Now 3 years later...no fatigue. I had serious lung problems going in and the radiation oncologist said there inevitably would be some sub-clinical damage. I have noticed maybe a 3-5% diminished breathing capacity, but I don't think that is noticeable with healthy lungs.
You can do this! Share your concerns with the techs as you go along--they know a lot. And keep in touch if you feel like it. It was a good treatment for my rare NET in breast, and I'm glad I did it.