[166Dy]Dysporium/[166Ho]Holmium In Vivo generator

A novel approach for the delivery of 166 Ho (image = 26.6 h) to tissue is via the in vivo decay of its 81.5 h parent, 166Dy—an in vivo generator system. A critical question for the in vivo166Dy/166Ho generator system is whether translocation of the daughter nucleus occurs. The in vitro and in vivo integrity of the [166Dy]Dy/166Ho-DTPA complex was investigated and results indicated that no translocation of the daughter nucleus occurs subsequent to β− decay of 166Dy. Biodistribution studies of [166Dy]Dy-DTPA showed that the ratio of 166Dy/166Ho in bone remains constant (± 7%) over a 20h period, indicating no Significant in vivo loss of 166Ho from the complex. Increasing the in vivo residence time of [166Dy]Dy-DTPA complex attached to HSA gave similar results.