Overseas visitors staying during radiation

I'd say no unless you know them very well and they are likely to be independent regarding their own needs and sympathetic to yours. Anyone high maintenance definitely needs to stay somewhere else. If you are at all unsure, consider fobbing them off. You may be absolutely fine, but you may not. Now is a good time to make a decision or at least flag that you may not be up to it so you don't have to retract an offer closer to the date. Let someone else step up so you can do what you need to do and participate as someone else's guest if you feel up to it.

That few weeks between chemo and rads is a very delicate time--treatment is physically and emotionally draining even for those who cope well and the side effects from chemo don't stop with your last infusion. Any extra stress is not needed. At all. Most of us find our houses fall into disarray and things like diet restrictions and fatigue can continue through radiation and beyond. Trying to accommodate someone else through that time is a big ask. I struggled with the poisoning and found radiation much easier, but I would have hated to have anyone around who needed looking after towards the end. Mind you, I'm notoriously grumpy and antisocial, so any excuse to avoid visitors will do for me :) Good luck, MXX