Accelerated partial breast radiation uses a high-dose-rate radioactive source, but is only in the breast for a brief time while the patient is in a shielded room. So, this will not cause you to be radioactive either.
The only time someone is temporarily "radioactive" is when radiation sources are permanently implanted inside the patient. Even then, it is only for a few days or weeks that precautions are taken with how close children or pregnant women can approach the patient. This is because the radioactive sources used today decay fairly quickly.
And PLEASE, do not be afraid to ask your radiation oncologist, or the therapists who will treat you daily, any questions you may have. We are always glad to try and answer them.