I agree with much of what Marko said. In my own words: It doesn’t hurt anything the way it is, but I would modify the ROI so that it doesn’t wrap around the contralateral side. You can always have separate ROIs for chin, bolus and arm should you need them, but I would likely use treatment capture for those like you suggested. That has been very helpful for us. After verifying the isocenter based on CBCT or KV/MV images, I would capture a reference image and then use that to help with daily setup.
I hope that helps!