For [225Ac]Ac-PSMA-based RLT, the maximum absorbed radiation dose per tumour per treatment cycle was a median 3-fold higher (IQR: 2–15) after ssIA administration (78 Gy, IQR: 38–142) compared to IV administration (18 Gy, IQR: 11–40), and therefore well beyond the estimated 95% CI after IV administration (85.2, 95% CI: 50.6–117.7 versus 23.5, 95% CI: 13.9–33.8). Here, FOLH1 is linked to neoplasm.