This is a very unusual disease, because it's so unpredictable. Some people have great results with chemo, and others have no improvement at all. It's the same with radiation. So we can't really say that chemo and radiation have similar effectiveness. Also, some patients can have radiation and others can't, because it depends on the location of the tumors.
But you should definitely ask if your mother can have radiation. For many people, the side effects are very mild. I had only heartburn (a burning feeling in my stomach) and some fatigue. For many people, the side effects of chemo are a lot more difficult.
The problem with radiation is that you have to go to the clinic five days a week for 4-6 weeks. But the treatments take only 5 minutes each time, and they are completely painless (like getting an x-ray.)
I hope this information helps you and your mother. I am SO happy to hear that she's feeling better, and that her mood is better too!
Best wishes to both of you,
Peace, hope, and healing to all!