Sue, I have asked same questions going through breast cancer 24 years ago and lived with osteoporosis since and I know my chemo definitely accelerated or caused my osteoporosis. I also had radiation and think my heart.calcium scores being so extremely high had to do with radiation though no doctor will address that.
Radiation can definitely affect our bones depending on how it was done. Maybe you can get more answers by asking your radiologist or oncologist. I was told my radiation would be targeted at only breast tissue but I now wonder how accurate that statement was.
I am sorry for all that is happening with you but you aren’t alone and so many nice people on this site are so helpful. It’s scary I know and after a breast cancer battle, it is even harder but you can do this for you are already a warrior. Keep in touch please.