Radionuclide generator

A radionuclide generator is a device which provides a local supply of a short-lived radioactive substance from the decay of a longer-lived parent radionuclide. They are commonly used in nuclear medicine to supply a radiopharmacy. The generator provides a way to separate the desired product from the parent, in a process that can be repeated a number of times over the life of the parent, as needed.
Use of a generator avoids the challenge of distributing short-lived radionuclides from the original production site to individual users; the loss of activity due to decay in transit can result in too little being supplied or the need for much larger initial quantities to be sent out. In many case an alternative to generator use is an on-site cyclotron producing the desired isotope; it is feasible to have cyclotrons at larger centres, but they are much more expensive and complex than generators. Even if the medical radionuclide's life is not that short, a generator may be used because of the low-cost availability of the parent, as with the strontium-90/yttrium-90 system.
Long-lived radionuclides which are administered to a patient with a view to utilising useful properties of a daughter product have been termed in-vivo generators, though they are not now routinely used clinically.

Commercial and experimental generators

	Parent		Daughter
Technetium generator	⁹⁹Mo	2.75 days	^99mTc	6.01 hours
Gallium generator	⁶⁸Ge	271.05 days	⁶⁸Ga	67.8 minutes
Rubidium generator	⁸²Sr	25.35 days	⁸²Rb	1.26 minutes
Copper generator	⁶²Zn	9.19 hours	⁶²Cu	9.67 minutes
Krypton generator	⁸¹Rb	4.572 hours	^81mKr	13.1 seconds
Yttrium generator	⁹⁰Sr	28.91 years	⁹⁰Y	64 hours
Rhenium generator	¹⁸⁸W	69.77 days	¹⁸⁸Re	17.0 hours