josgen,
I did not have the 5 treatment but the 30 treatments of proton. I have medicare and BCBS federal. I am looking at my Medicare MSN.
Intermediate proton beam radiation treatment: Provider charged: 5,300.00. Medicare approved amount 1,071.48. Medicare paid 839.76. So I would have had to pay 214.23 out of pocket but my BCBS pays what Medicare does not.

If you have xray guidance with your treatments that is another charge. On mine I saw it different. On several it was 350.00 charged, approved 72.35 and paid 56.72. My out of pocket would have been 14.47.

If you have other tests done they can be very very expensive. I think my PSMA (done at Shands/co located next to UFPTI) was 18,340.00 with Medicare approving 18,340.00 and paying 5,741.68. My nuclear study CT was 17,082.00 Medicare approve all and paid 1,055.21. As you can see sometimes Medicare pays below approved amount and has to do with something about Federal, State, and local rules. My out of pocket for the 17,082 would have been 269.19 not the difference in approved and what was paid.

Does this help you with some figuring? Basically Medicare will pay 80% of the approved amount. Your provider must be a Medicare Acceptance Facility and thus can only bill you for what Medicare approves. You will have to pay the 20% out of pocket if you do not have secondary insurance.