what to expect

Like previous poster, I had a lumpectomy (a sizable one) not a mastectomy but the timeline for starting rads is likely the same. Assuming you require radiation and also that you are not having chemotherapy, the next step is to meet with a radiation oncologist who will likely want you to begin treatments as soon as healing is underway (OK to not be completely) to kill any teeny missed bc cells, typically 4-6 weeks from surgery. Mine was slightly delayed by a snb surgery 14 days after lump. surgery, and my treatments (a.k.a. zaps) began ~7 weeks after lumpectomy.

The waiting is among the hardest parts and hopefully you will find that things progress quickly after that session with your RO. I came in for only 2 more session before the zaps began: first session lasted under an hour and consisted of some CT scans and measurements.  I remember they kept tugging me around on the paper on the table, having me lean a particular way and stay still -- you kinda feel like a piece of meat so it is best to just try to mentally disconnect (such a had thing, I know). This is when they also typically mark you up, either with permanent tattoos or, in my case was happy to instead have sharpie marker marks and stickers. I came back a week or so later, once everything was all calculated and discussed, for a final run-through to just make sure that the beams all lined up with the markings as they were intended, and this session was faster, maybe 15 minutes.

The actual treatments are very quick (like a minute or two), my place scheduled patients for every 15 minutes on each machine (I always stayed with the exact same machine). I spent more time driving to/from and also more time changing and sitting in the waiting room then any session ever lasted. I had 25 full-breast treatments only -- no collarbone or nodes/underarm -- followed by 5 boosts to the scar area, with the first 25 treatments in the prone (face down) position.

Good luck and keep posting if you have questions.