Radionuclide or Radioisotope? How Nuclear Medicine Actually Uses the Terms

Thu, 05 Nov 2026 09:00:00 +0000

Walk into any nuclear medicine department and you will hear “isotope” and “radionuclide” used as if they meant the same thing. Usually nobody is confused. But the two words are not synonyms, and the difference shows up in exactly the places nuclear medicine cares about most: generators, theranostic pairs and metastable states such as technetium-99m.

When we renamed the section on our homepage from Isotopes to Radionuclides, we checked the reasoning against how authors in The Journal of Nuclear Medicine (JNM) actually use the two words. This post sets out the physics, then what twelve JNM articles published between 2018 and 2026 show, and finally the convention we follow on XNucMed.