Radionuclide generator

{{Short description|Device for creating radionuclides}} {{for|the device that generates electricity from radioactive decay|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.<ref>{{cite book |last1=Rösch |first1=F |last2=Knapp |first2=F F |editor1-last=Vértes |editor1-first=Attila |editor2-last=Nagy |editor2-first=Sándor |editor3-last=Klencsár |editor3-first=Zoltan |editor4-last=Lovas |editor4-first=Rezső G. |title=Handbook of Nuclear Chemistry: Radiochemistry and radiopharmaceutical chemistry in life sciences |date=2003 |publisher=Springer Science & Business Media |isbn=9781402013164 |chapter-url=https://books.google.com/books?id=0skQvMEa8EYC&pg=PA81 |language=en |chapter=Radionuclide Generators}}</ref> 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,<ref name="MI2009">{{cite book |last1=Vallabhajosula |first1=Shankar |title=Molecular Imaging: Radiopharmaceuticals for PET and SPECT |date=2009 |publisher=Springer Science & Business Media |isbn=9783540767350 |page=56 |url=https://books.google.com/books?id=bUmcxfnlkt8C&pg=PA56 |language=en}}</ref><ref>{{cite book |last1=Saha |first1=Gopal B. |title=Fundamentals of Nuclear Pharmacy |date=2010 |publisher=Springer |isbn=9781441958600 |page=67 |url=https://books.google.com/books?id=bEXqI4ACk-AC&pg=PA67 |language=en}}</ref> 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).<ref>{{cite journal |last1=Currie |first1=GM |last2=Wheat |first2=JM |last3=Davidson |first3=R |last4=Kiat |first4=H |title=Radionuclide production |journal=Radiographer |date=September 2011 |volume=58 |issue=3 |pages=46–52 |doi=10.1002/j.2051-3909.2011.tb00155.x|doi-access=free}}</ref> 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.<ref name="IAEA-cyclotron">{{cite book |last1=IAEA |title=Cyclotron produced radionuclides : principles and practice. |date=2008 |publisher=International Atomic Energy Agency |location=Vienna |isbn=978-92-0-100208-2 |url=https://www.iaea.org/publications/7849/cyclotron-produced-radionuclides-principles-and-practice}}</ref> 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.<ref>{{cite journal |last1=Edem |first1=Patricia E. |last2=Fonslet |first2=Jesper |last3=Kjær |first3=Andreas |last4=Herth |first4=Matthias |last5=Severin |first5=Gregory |title=In Vivo Radionuclide Generators for Diagnostics and Therapy |journal=Bioinorganic Chemistry and Applications |date=2016 |volume=2016 |pages=1–8 |doi=10.1155/2016/6148357 |pmid=28058040 |pmc=5183759 |doi-access=free }}</ref>

==Commercial and experimental generators==

{| class="wikitable" |- ! !! 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<ref>{{cite journal |editor1-last=Waters |editor1-first=S. L. |editor2-last=Coursey |editor2-first=B. M. |title=The Strontium-82/rubidium-82 generator |journal=International Journal of Radiation Applications and Instrumentation A |volume=38 |issue=3 |pages=171–239 |year=1987 |url=http://www.sciencedirect.com/science/journal/08832889/38/3}}</ref> || ⁸²Sr || 25.35 days || ⁸²Rb || 1.26 minutes |- | Copper generator<ref name="MI2009" /> || ⁶²Zn || 9.19 hours || ⁶²Cu || 9.67 minutes |- | Krypton generator<ref>{{cite journal |last1=Fremlin |first1=John H |last2=Stammers |first2=Keith |last3=Stewart |first3=Frederick R |title=A new generator for krypton-81m |journal=Nuclear Instruments and Methods |date=November 1978 |volume=156 |issue=3 |pages=369–373 |doi=10.1016/0029-554X(78)90739-5}}</ref> || ⁸¹Rb || 4.572 hours || ^81mKr || 13.1 seconds |- | Yttrium generator<ref name="IAEAtheragen">{{cite book |last1=IAEA |title=Therapeutic radionuclide generators : ⁹⁰Sr/⁹⁰Y and ¹⁸⁸W/¹⁸⁸Re generators. |publisher=International Atomic Energy Agency |isbn=978-92-0-111408-2 |location=Vienna |date=2009 |url=https://www.iaea.org/publications/8045/therapeutic-radionuclide-generators-90sr/90y-and-188w/188re-generators}}</ref> || ⁹⁰Sr || 28.91 years || ⁹⁰Y || 64 hours |- | Rhenium generator<ref name="IAEAtheragen" /> || ¹⁸⁸W || 69.77 days || ¹⁸⁸Re || 17.0 hours |}

==Further reading== *{{cite web |last1=IAEA |title=Generator Module |url=https://humanhealth.iaea.org/HHW/Radiopharmacy/VirRad/Eluting_the_Generator/Generator_Module/index.html |website=Human Health Campus |publisher=International Atomic Energy Agency}}

==References== {{reflist}}

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Category:Nuclear medicine

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