FOLH1 and prostate cancer: This study aims to determine the feasibility of BgRT to PSMA-negative/FDG-positive prostate cancer metastases, to report the anatomical distribution of PSMA-negative/FDG-positive tumours in the subset of excluded patients from the LuPSMA clinical trial, and to determine the proportion of PSMA-negative/FDG-positive tumours suitable for BgRT, in the context of a theoretical workflow for BgRT.