More α Than β for Prostate Cancer?

Proportion of targeted tumor volume per total irradiated volume for α- (²²⁵Ac) versus β- (¹⁷⁷Lu) radioligand therapy of small prostate cancer lesions. Maximum range in tissue is 0.1 mm for α- and 2 mm for β-therapy. Radiation delivered to subcentimeter lesions drops significantly for β-therapy, as energy deposition significantly extends beyond lesion boundaries. The simplified model calculates irradiated volumes assuming homogeneous intratumoral distribution of ²²⁵Ac and ¹⁷⁷Lu without taking into account any potential difference in biodistribution, energy transfer, and relative biologic effectiveness.