Dr Li: Okay, I'll take a look. It looks a little discolored. We'll get a set of X-rays today to get to the bottom of it.
Tina: X-rays? Will that be an out-of-pocket expense?
Dr Li: No, you're due for a set. It'll be covered by your insurance.
If you break it down what does "due"& "a set" mean and also overall meaning?