Comparing the biodistribution of [161Tb]Tb-PSMA-617 to that of [177Lu]Lu-PSMA-617, a similar distribution pattern was observed over time with intense uptake of radiolabeled PSMA ligands in salivary glands, kidneys, liver, and small intestine and a high retention in tumor lesions. The gene discussed is FOLH1; the disease is neoplasm.