@mnewland99 , I would be interested if you could ask your oncologist (medical and/or radiation) is there is any path forward for you to use something like the Civa Sheet. It's a sheet of radioactive pellets that can be surgically placed over a generalized area to provide "one-way" radiation of that area. The gold backing prevents radiation from coming out the other side and affecting healthy tissue nearby.
https://civatechoncology.com/civasheet/
One of their images on that web page shows it attached to the SMA. I wonder if that could help @ncteacher and others with arterial involvement.

There are also several centers offering Hepatic Arterial Infusion Pumps. One example:
https://hillman.upmc.com/cancer-care/surgical-oncology/koch-regional-cancer-therapy-center/treatments/hepatic-arterial-infusion
They inject chemo directly into an artery that feeds your liver, which produces a much more concentrated dose where it's needed. The UPMC link above describes it primarily in the context of liver mets from colorectal cancer, but it seems applicable in general to this non-medically-trained outside observer.

One of the pancreas/liver surgeons at Mayo/Jax (Katherine Poruk) has this procedure listed on her bio page as well.