@1hockeyjeff, Ductal carcinoma of the prostate is a rare variant of prostate cancer. Knowing that you have this variant helps your team develop the most effective treatment plan for this type.

From Mayo Clinic
"Intensity-modulated radiation therapy (IMRT) is an advanced type of radiation therapy used to treat cancer. IMRT uses advanced technology to manipulate photon and proton beams of radiation to conform to the shape of a tumor.

Proton beam therapy (PBT) is precise like IMRT, but it uses proton beams instead of x-ray beams. IMRT and PBT aim to deliver most of the radiation to the prostate cancer while sparing surrounding tissues. Both IMRT and PBT have been used in the treatment of prostate cancer and are thought to be equally effective treatments."

Fellow members @spryguy @biih and @zj69 have also mentioned that they have intraductal carcinoma of the prostate. Perhaps they have some insight.

Jeff, like you, I'd be interested in a more detailed explanation from your radiologist about why IMRT is used but proton beam therapy is not. When do you see your radio-oncologist again?