Just heard back from the rad Onco doc in HK. Here's what he had to say:

"The apexes of both lungs will be at the level of the collar bones. It is quite common for fibrosis to result from radiation treatment but it will not cause any dysfunction of your lung. So don't worry about it and just ignore it. There is no need to repeat the CXR. One should only be concerned when you feel shortness of breathe"

Since the appointment is already made, insurance is paying for it, and I don't have to get poked with a needle I'll go ahead and have the CRX done anyway just to be on the safe side.

Another one of those lovely side effects that no one tells you about.