I went through 10 radiation treatments in January 2013. It was about 8 months after the onset of TED symptoms. I had moderate double vision and was starting to lose color vision.
The 2nd week of treatment and a few weeks after treatment were pretty rough. The radiation caused nausea, exhaustion and pretty significant skin irritation. Plus I lost all of my eyelashes, lol.
BUT…based on the results I would do it again in a minute. My doctor had warned me that the hope of the treatment was to stop the progression of TED, not reverse what had already been done. However, within 3 months my double vision was gone, my color vision returned and instead of facing OD and eye muscle surgery, I have just had surgery to repair my upper eyelid retraction.
The radiation oncologist did lay out the risks pretty clearly – cataracts, meningiomas or something more sinister. I had a hard time deciding, but ultimately figured the risk of getting cancer in 40 years was still better than the risks TED was presenting in that moment.
It is a pretty serious decision and I wish you luck in whatever you decide.