My adventure with radiation was for prostate cancer a year and a half before I started getting MG symptoms.

I had a 9 week course of 5 days a week radiation therapy. I was pretty OK until about week #6, then a few people around me started remarking on how tired I looked. That got me to notice that I had been felling pretty crappy for a week or so.

The Dr. said that was right about On Schedule.

I was pretty tired for about 2+ months after that, then started getting back to normal over the next 6 months.

Just my experience. Your mileage may vary.