PRIT:RIT ratios obtained from comparative biodistributions of PRIT and RIT in the tumors, blood, and normal organs of athymic mice bearing Ramos xenografts. The % ID/g of tissue were obtained in 2 separate experiments using 1F5 Ab in a conventional RIT and PRIT schemes. The ratio of PRIT to RIT for % ID/g of each tissue was calculated for direct comparison.