For me, they administered 2.5 Grays of proton radiation to the entire prostate at each of my 28 sessions.

Depending on the nature of your diagnosis, they very likely treated your entire prostate with the same amount of radiation each session.

(There is a protocol called the FLAME Protocol where they use mpMRI to precisely identify the dominant tumor(s) within the prostate, deliver a standard dose to the whole prostate, plus an extra boost specifically to the visible tumor(s). My brother recently had his IMRT radiation treatments using this protocol.)