Radionuclide generator

For the device that generates electricity from radioactive decay, see radioisotope 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 (a nuclear reactor or cyclotron) 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 (incurring additional production and transport costs). 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	(half-life)	Daughter	(half-life)
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