Table 1.

Generators for clinical productions of radionuclides.

Generator	Parent Half-Life	Daughter Half-Life	Frequency of Milking
99Mo/99mTc	2.8 days	6 h	*
188W/188Re	70 days	17 h	24 h
68Ge/68Ga	271 days	68 min	6 h
229Th/225Ac	7920 years	9.9 days	*

*: Frequency of milking depends upon generator size.