Here's an intriguing abstract from the ASCO conference that is going on right now (February 2023). Hofman and company in Australia are starting a clinical trial (NCT05521412) to evaluate using Tb-161 instead of Lu-177 linked to the PSMA-I&T targeting ligand.
The hope is that the shorter range and higher energy (Auger electrons) of Tb-161 will help to attack smaller and isolated collections of PSMA-expressing prostate cancer cells, resulting in more durable responses. I don't see any speculation in the abstract about whether this also might cause more salivary gland toxicity.
VIOLET: A phase I/II trial evaluation of radioligand treatment in men with metastatic castration-resistant prostate cancer with [161Tb]Tb-PSMA-I&T.
