[{"id":"ac-225","kind":"isotope","name":"Actinium-225","aka":["225Ac","Ac-225"],"tldr":"A metal that fires off very powerful, very short-range radioactive particles as it decays through a chain of daughter atoms. Because the particles barely travel beyond the cell they hit, it can kill a cancer cell while leaving neighbouring healthy cells mostly untouched. Supply is scarce, so it is still mostly used in research studies.","summary":"Actinium-225 decays by alpha emission through six short-lived daughters to stable bismuth-209, releasing a net four alpha particles per decay (a 'nanogenerator'). At 9.9 days its half-life is long enough for centralised manufacture and international shipping, unlike its short-lived daughter bismuth-213.\n\nThe historical route extracts 225Ac from decaying stockpiles of thorium-229 (itself from aged uranium-233), 'milked' every few weeks; the amounts are milligram/curie-scale and cannot be scaled much further. Newer accelerator routes -- proton spallation of thorium-232, or proton irradiation of radium-226 targets via 226Ra(p,2n)225Ac -- are being industrialised by the DOE's Tri-Lab effort (Brookhaven, Los Alamos, Oak Ridge) and by companies building cyclotron and linac capacity.\n\nSupply is the most contested number in the field. A 2023 Journal of Nuclear Medicine analysis put worldwide 229Th/225Ac-derived supply at roughly 63 GBq (1.7 Ci) per year, enough for only 100-200 patients, against a stated need for hundreds to thousands of curies a year if approved 225Ac drugs reach broad use; it projected accelerator and photonuclear routes could reach over 25 TBq (670 Ci) a year worldwide by 2032. Other DOE and IAEA figures from 2013-2021 cite current 229Th-derived supply at 1-2 Ci/year (37-74 GBq) split mainly between Oak Ridge National Laboratory (ORNL, USA), the Joint Research Centre in Karlsruhe (Germany, ~13 GBq/year) and IPPE Obninsk (Russia, ~22 GBq/year), and note the same production facilities co-produce the long-lived impurity 227Ac (half-life 21.8 years) at the 0.1-0.2% level, which complicates waste handling and dosimetry.","status":"phase-2","asOf":"2026-09-22","links":[{"label":"Is Actinium Really Happening? (Journal of Nuclear Medicine, 2023)","url":"https://jnm.snmjournals.org/content/64/10/1516"},{"label":"DOE Isotope Program: Production Methods for Ac-225","url":"https://www.isotopes.gov/information/actinium-225"},{"label":"Supply and Clinical Application of Actinium-225 and Bismuth-213 (PMC, 2020)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC7082773/"},{"label":"Actinium-225 in targeted alpha-particle therapeutic applications (PMC)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC5565267/"}],"tags":["therapy","alpha emitter","supply-constrained"],"related":["ac225-psma","ryz101","fpi-2265","targeted-alpha-therapy","actinium-225-supply","idea-reg-ac225-accelerator-pharmacopoeia","idea-reg-legacy-radium-recovery-ac225","bi-213"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"225Ac","element":"Actinium","massNumber":225,"halfLife":"9.92 days","emissions":["α 5.8 MeV (225Ac itself)","α, β and γ from the six-member decay chain to stable 209Bi (net 4 α, 3 β, 2 useful γ per decay)"],"emissionClass":"alpha","use":"therapy","tissueRange":"A few cell diameters (tens of micrometres)","production":"Decay of parent 229Th stockpiles ('milked' periodically), or accelerator: proton spallation of 232Th, or cyclotron 226Ra(p,2n)225Ac.","supply":"constrained","supplyNote":"Disputed. JNM (2023) estimated current 229Th-derived worldwide supply at ~63 GBq (1.7 Ci)/year, enough for 100-200 patients/year, versus a need in the hundreds-to-thousands of Ci/year for broad approval; it projected >25 TBq (670 Ci)/year of installed capacity worldwide by 2032 from accelerator and photonuclear routes. Earlier DOE/IAEA figures (2013-2021) put current 229Th/225Ac supply at roughly 1.2-1.7 Ci/year split between ORNL (USA), JRC Karlsruhe (Germany) and IPPE Obninsk (Russia).","chelators":["DOTA","macropa"],"pairedWith":["ga-68"]},{"id":"at-211","kind":"isotope","name":"Astatine-211","aka":["211At","At-211"],"tldr":"A radioactive halogen, chemically similar to iodine, that gives off a single powerful short-range particle as it decays. It has to be made in a particular kind of accelerator and used within hours, which is why only a handful of centres worldwide can supply it.","summary":"Astatine-211 decays with a 7.2-hour half-life entirely by alpha emission, branching between two paths: about 41.8% via direct alpha emission to long-lived 207Bi, and about 58.2% via alpha decay to 211Po (half-life 0.52 s), which itself alpha-decays to stable 207Pb. Because astatine sits in the halogen group, it can in principle use much of the same radiochemistry developed for radioiodine (e.g. astato-benzylguanidine as an analogue of iobenguane).\n\nIt is made almost exclusively by bombarding natural, monoisotopic bismuth-209 targets with alpha particles in a cyclotron via the 209Bi(α,2n)211At reaction, which requires a beam of around 28-29.5 MeV; energies above this range increasingly co-produce the long-lived, more radiotoxic contaminant 210At (which decays to 210Po), so machines are tuned to stay just below or at that threshold.\n\nSupply is the binding constraint: as of the mid-2020s only a handful of cyclotrons worldwide routinely produce clinical-grade 211At, including Copenhagen (Denmark), Arronax in Nantes (France), Duke University, the University of Washington and Ionetix (Michigan, first US commercial supplier, shipping since September 2026) in the US, with new or restarting capacity in Poland, Czechia, the UK and South Korea. Because of the 7.2-hour half-life, 211At must be produced close to where it will be used and cannot be stockpiled or shipped over long distances.","status":"phase-1","asOf":"2026-09-22","links":[{"label":"Astatine-211: Production and Availability (Curr Radiopharm, PMC)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC3503149/"},{"label":"Solving the limited availability of Astatine-211 from a European perspective (PMC, 2026)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC12929731/"},{"label":"Ionetix: Ionetix Begins Shipping Astatine-211 to Support Preclinical and Clinical Trials (2026)","url":"https://ionetix.com/2026/09/01/ionetix-begins-shipping-astatine-211-to-support-preclinical-and-clinical-trials/"}],"tags":["therapy","alpha emitter","halogen","supply-constrained"],"related":["astatine-211-alpha-therapy","targeted-alpha-therapy","cyclotron-isotope-production","idea-reg-alpha-emitter-portfolio"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"211At","element":"Astatine","massNumber":211,"halfLife":"7.21 hours","emissions":["α 5.87 MeV (41.8%, to 207Bi)","α 7.45 MeV (58.2%, via 211Po to stable 207Pb)"],"emissionClass":"alpha","use":"therapy","tissueRange":"Tens of micrometres (alpha range)","production":"Cyclotron: alpha-particle bombardment of natural bismuth-209 targets, 209Bi(α,2n)211At, at about 28-29.5 MeV.","supply":"research-only","supplyNote":"Requires a medium-energy (~28-30 MeV) alpha-beam cyclotron; only a handful of sites worldwide (Copenhagen, Arronax/Nantes, Duke, University of Washington, and since 2026 Ionetix in Michigan as the first US commercial supplier) produce it routinely, and its 7.2-hour half-life rules out long-distance shipping.","chelators":[],"pairedWith":["i-123"]},{"id":"bi-213","kind":"isotope","name":"Bismuth-213","aka":["213Bi","Bi-213"],"tldr":"An extremely short-lived radioactive metal that delivers a powerful, very local burst of radiation. Because it decays away within a few hours, it has to be made freshly at the hospital, right before it is given to the patient.","summary":"Bismuth-213 is a daughter of actinium-225 with a half-life of only 45.6 minutes. It decays by branching: about 97.8% by beta emission to the ultra-short-lived pure alpha emitter polonium-213 (half-life about 4 microseconds), and a small fraction (roughly 2%) directly by alpha emission to thallium-209. Around 92-93% of the energy released per 213Bi decay is ultimately carried by alpha particles.\n\nBecause its half-life is far shorter than any other clinical radiotherapeutic isotope, 213Bi cannot be centrally manufactured and shipped; it is produced on demand from a 225Ac/213Bi radionuclide generator, typically eluted every two to three hours in clinical use, giving elution yields around 83-93%. The main generator design (an AG MP-50 cation-exchange resin loaded with 225Ac) was pioneered at the Joint Research Centre in Karlsruhe, Germany, which has supplied it free of charge for clinical trials in Europe and the US.\n\n213Bi shares essentially all of 225Ac's supply constraints, since it is milked from the same scarce 225Ac stock, and using it consumes 225Ac less efficiently per alpha particle delivered than using 225Ac directly (only the final alpha of the decay chain is captured). It has been used in early-phase trials in leukaemia, glioma, melanoma, bladder cancer, lymphoma and neuroendocrine tumours, most with anti-CD33 or similar targeting constructs, but has not reached late-phase development.","status":"phase-1","asOf":"2026-09-22","links":[{"label":"Bismuth-213 for Targeted Radionuclide Therapy (Pharmaceutics, 2021)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC8143329/"},{"label":"Actinium-225/Bismuth-213 as Potential Leaders for Targeted Alpha Therapy (Pharmaceutics, 2025)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC12468084/"},{"label":"Bismuth-213 and Actinium-225 - Generator Performance (Current Radiopharmaceuticals, 2012)","url":"https://www.ingentaconnect.com/content/ben/crp/2012/00000005/00000003/art00006"}],"tags":["therapy","alpha emitter","generator-produced","short-lived"],"related":["ac-225","targeted-alpha-therapy","idea-reg-alpha-emitter-portfolio"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"213Bi","element":"Bismuth","massNumber":213,"halfLife":"45.6 minutes","emissions":["β− 444 keV (97.84%, to 213Po)","α 5.55-5.87 MeV (about 2%, direct to 209Tl)","213Po α 8.375 MeV in vivo (from the β− branch)","γ 440 keV (usable for imaging)"],"emissionClass":"mixed","use":"therapy","tissueRange":"40-80 micrometres (alpha range)","production":"Generator: eluted from a 225Ac/213Bi radionuclide generator (cation-exchange resin loaded with 225Ac), typically every 2-3 hours.","supply":"constrained","supplyNote":"Entirely dependent on the same scarce 225Ac supply (see ac-225); the JRC Karlsruhe 225Ac/213Bi generator has been the main clinical-trial source in Europe and the US, supplied without charge for research use.","chelators":["DTPA-based bifunctional chelators","CHX-A''-DTPA"],"pairedWith":["ga-68"]},{"id":"c-11","kind":"isotope","name":"Carbon-11","aka":["11C"],"tldr":"A radioactive form of ordinary carbon that lasts only about 20 minutes, so it has to be made and used in the same building; it can label real body molecules like choline without changing their chemistry.","summary":"Carbon-11 decays by positron emission (about 99.8% of the time) with a physical half-life of only 20.4 minutes, the shortest half-life of any radionuclide in routine clinical use. Because carbon is the backbone atom of biological molecules, replacing a stable carbon-12 with carbon-11 gives a radiotracer that is chemically indistinguishable from its natural counterpart, unlike fluorine- or metal-based tracers that are typically synthetic analogues.\n\nThe half-life is so short that C-11 cannot be shipped: it must be produced, synthesised into a tracer, quality-tested and injected within the same facility, on the same clock, which is why C-11 programmes exist only at large academic or hospital sites with an on-site cyclotron and radiochemistry suite immediately adjacent to the PET scanner. Almost all clinical C-11 comes from the 14N(p,α)11C reaction, bombarding nitrogen gas with protons to give [11C]carbon dioxide or, with added hydrogen, [11C]methane, which is then converted to the reactive methylating agent [11C]methyl iodide or [11C]methyl triflate to label a precursor molecule such as choline or methionine.\n\nCholine C-11 was approved by the FDA in September 2012 for PET imaging of suspected recurrent prostate cancer with non-informative conventional imaging, and remains one of the few full-NDA radiopharmaceuticals that can only be produced and used on site.","status":"established","asOf":"2026-09-22","links":[{"label":"FDA label: Choline C 11 Injection (NDA 203155, approved 12 Sep 2012)","url":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=61f00cb4-ea53-4ba6-a890-78586095d2f6"},{"label":"PMC: synthesis, isolation and purification of [11C]-choline","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC5013686/"}],"tags":["positron emitter","ultra-short-lived","on-site only"],"related":["choline-c11"],"indications":["prostate"],"sections":[],"technologies":["pet","cyclotron-isotope-production","choline-metabolism-in-cancer"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"11C","element":"Carbon","massNumber":11,"halfLife":"20.4 minutes","emissions":["β+ ~99.8% (max 0.96 MeV)","electron capture ~0.2%"],"emissionClass":"positron","use":"imaging","production":"Cyclotron: 14N(p,α)11C on nitrogen gas target (with trace oxygen for [11C]CO2 or trace hydrogen for [11C]CH4), converted to [11C]methyl iodide or [11C]methyl triflate for labelling.","supply":"research-only","supplyNote":"The 20.4-minute half-life rules out shipping entirely; every dose is made and used at the same site, so availability is limited to institutions with an on-site cyclotron and radiochemistry, mostly academic centres.","chelators":[],"pairedWith":[],"since":1973},{"id":"cu-64","kind":"isotope","name":"Copper-64","aka":["64Cu"],"tldr":"A radioactive metal that lasts about half a day, long enough to image slower-moving molecules such as antibodies, and chemically identical to copper-67, the isotope used to treat with the same tracer.","summary":"Copper-64 has an unusually long half-life for a positron emitter, 12.7 hours, and a three-way decay: 17.5-19% positron emission, roughly 40-44% electron capture, and about 38-39% beta-minus decay, so the same nuclide gives PET signal and a small therapeutic beta dose. Its half-life is long enough to image both fast-clearing peptides and slower-clearing antibodies and nanoparticles, and it forms a same-element theranostic pair with copper-67, which shares the identical chelation chemistry so a diagnostic 64Cu scan predicts the biodistribution of a 67Cu therapy exactly.\n\nIt is produced almost exclusively on medical cyclotrons via 64Ni(p,n)64Cu on an enriched nickel-64 target electroplated onto a metal backing, a well-established, high-specific-activity route; a bombardment of a few hours on a 40 mg target can yield roughly 18.5 GBq. Reactor routes (64Zn(n,p)64Cu, 63Cu(n,γ)64Cu) exist but give lower specific activity and are used less often clinically.\n\nBecause the 64Ni target is expensive and the reaction requires a dedicated cyclotron run, 64Cu is made at a limited number of centres and supplied regionally rather than being universally available the way 18F is; the sstr2-targeted 64Cu-DOTATATE (Detectnet) is the main approved clinical use in the United States.","status":"approved","asOf":"2026-09-22","links":[{"label":"IAEA: copper-64 radiopharmaceuticals, production, quality control","url":"https://www-pub.iaea.org/MTCD/Publications/PDF/PUB1961_web.pdf"},{"label":"PMC: recent advances in 64Cu/67Cu-based radiopharmaceuticals (2023)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC10288943/"}],"tags":["positron emitter","theranostic pair","same-element pair"],"related":["ga68-dotatate"],"indications":[],"sections":[],"technologies":["sstr-pet","pet","cyclotron-isotope-production"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"64Cu","element":"Copper","massNumber":64,"halfLife":"12.7 hours","emissions":["β+ 17.5% (max 0.653 MeV)","electron capture ~44%","β− 38.5% (max 0.579 MeV)","annihilation γ 511 keV"],"emissionClass":"mixed","use":"imaging","production":"Cyclotron: 64Ni(p,n)64Cu on enriched nickel-64 target (dominant route); reactor 64Zn(n,p)64Cu or 63Cu(n,γ)64Cu give lower specific activity.","supply":"emerging","supplyNote":"Limited to cyclotron centres with enriched 64Ni targets; regional supply rather than universal, but expanding alongside interest in the 64Cu/67Cu theranostic pair.","chelators":["DOTA","SARTATE/SAR-bisPSMA (sarcophagine cages)"],"pairedWith":["cu-67"],"since":2020},{"id":"cu-67","kind":"isotope","name":"Copper-67","aka":["67Cu","Cu-67"],"tldr":"A radioactive form of copper that pairs with a diagnostic twin made of the same element, copper-64. Using the same metal for the scan and the treatment means the tracer behaves identically both times, which should make dosing more predictable.","summary":"Copper-67 decays purely by beta-minus emission with a physical half-life of 61.8-62 hours (about 2.58 days) to stable zinc-67, with a mean beta energy of about 141 keV (maximum energies at 377, 468 and 562 keV) and useful imaging gammas at 93 keV and 184.6 keV (about 49% abundance), which support SPECT-based dosimetry.\n\nIts principal theranostic appeal is chemical identity with copper-64, the positron-emitting isotope used for PET imaging of the same chelator-conjugated agent (e.g. SAR-bisPSMA, SARTATE): the same molecule with the same biodistribution can be imaged pre-therapy with 64Cu and then dosed with 67Cu, avoiding the surrogate mismatch inherent in most other theranostic pairs.\n\nProduction historically used reactor or lower-energy cyclotron reactions (67Zn(n,p)67Cu, 68Zn(p,2p)67Cu, 70Zn(p,α)67Cu), each limited to modest specific activity. A step change came from high-energy bremsstrahlung photonuclear production, 68Zn(γ,p)67Cu, using electron linear accelerators to irradiate enriched 68Zn targets; the US Department of Energy Isotope Program's Low Energy Accelerator Facility (LEAF) uses this route to supply no-carrier-added 67Cu at specific activities above 1850 GBq/mg. Clarity Pharmaceuticals and the DOE Isotope Program are among the groups scaling supply; 67Cu is not dependent on nuclear reactor neutron flux, so it avoids the reactor-capacity bottleneck that constrains 177Lu and 225Ac.","status":"phase-2","asOf":"2026-09-22","links":[{"label":"Recent Advances in 64Cu/67Cu-Based Radiopharmaceuticals (Pharmaceutics, 2023)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC10288943/"},{"label":"67Cu Production Capabilities: A Mini Review (Front Med, 2022)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC8912090/"},{"label":"Copper-67 radioimmunotheranostics for simultaneous immunotherapy and immuno-SPECT (Scientific Reports, 2021)","url":"https://www.nature.com/articles/s41598-021-82812-1"},{"label":"Clarity Pharmaceuticals: Copper-64 and Copper-67 - The Perfect Theranostic Pairing","url":"https://www.claritypharmaceuticals.com/technology/copper-isotopes/"}],"tags":["therapy","beta emitter","theranostic pair"],"related":["nct04868604","nct06298916","clarity-pharmaceuticals","cu-64"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"67Cu","element":"Copper","massNumber":67,"halfLife":"61.8 hours (2.58 days)","emissions":["β− mean 141 keV (maxima 377/468/562 keV)","γ 93.3 keV (7-16%)","γ 184.6 keV (~49%)"],"emissionClass":"beta-minus","use":"therapy","tissueRange":"About 0.7 mm mean (comparable to 177Lu)","production":"Accelerator: bremsstrahlung photonuclear reaction on enriched zinc-68, 68Zn(γ,p)67Cu, using an electron linear accelerator; also reactor 67Zn(n,p)67Cu or cyclotron 68Zn(p,2p)67Cu / 70Zn(p,α)67Cu.","supply":"emerging","supplyNote":"The photonuclear 68Zn(γ,p)67Cu route (US DOE Isotope Program's LEAF facility) yields high-specific-activity, no-carrier-added 67Cu without needing reactor neutron flux, easing the bottlenecks that affect 177Lu and 225Ac; supply is scaling but still limited relative to established isotopes.","chelators":["SarAr/SAR-type sarcophagine cages","DOTA"],"pairedWith":["cu-64"]},{"id":"f-18","kind":"isotope","name":"Fluorine-18","aka":["18F"],"tldr":"A short-lived radioactive form of fluorine, made fresh each morning at a local facility, that is attached to a sugar or other small molecule and used for a PET scan.","summary":"Fluorine-18 is the workhorse radionuclide of clinical PET. Its 109.8-minute half-life is long enough for a regional cyclotron to make a batch, run it through automated radiochemistry and quality control, and ship unit doses to nearby hospitals, but short enough that the whole chain has to be scheduled tightly around the day's scan list; roughly a third of the activity is lost every hour.\n\nAlmost all clinical 18F is made by firing protons at water enriched in oxygen-18, driving the 18O(p,n)18F reaction to give no-carrier-added [18F]fluoride in solution, which is then used in automated synthesis modules to build tracers such as FDG, PSMA and amyloid agents. It decays 96.7% by positron emission and 3.3% by electron capture, giving the 511 keV annihilation photon pair that PET detects.\n\nBecause the half-life supports regional distribution, F-18 tracers do not depend on a single generator or reactor the way technetium-99m or gallium-68 historically have; supply risk sits instead with cyclotron and radiopharmacy network capacity (PETNET, Cardinal Health, GE HealthCare, Jubilant, SOFIE and others) rather than with a single upstream bottleneck.","status":"established","asOf":"2026-09-22","links":[{"label":"FDA label: Fludeoxyglucose F 18 Injection (initial approval 2005)","url":"https://www.accessdata.fda.gov/drugsatfda_docs/label/2005/021870lbl.pdf"},{"label":"IAEA TRS 468: cyclotron production of 18F","url":"https://www-pub.iaea.org/MTCD/Publications/PDF/trs468_web.pdf"},{"label":"PMC: PET imaging with 18F-based radiopharmaceuticals","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC3478111/"}],"tags":["positron emitter","cyclotron"],"related":["fludeoxyglucose-f18","pylarify","psma-1007-f18","fluoroestradiol-f18","flotufolastat","fluciclovine-f18"],"indications":[],"sections":[],"technologies":["pet","pet-ct","cyclotron-isotope-production","pet-tracer-manufacturing","fdg-pet","psma-pet"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"18F","element":"Fluorine","massNumber":18,"halfLife":"109.8 minutes","emissions":["β+ 96.7% (max 0.634 MeV)","electron capture 3.3%","annihilation γ 511 keV"],"emissionClass":"positron","use":"imaging","production":"Cyclotron: 18O(p,n)18F on water enriched in oxygen-18 (no-carrier-added fluoride); 20Ne(d,α)18F on neon gas is an older electrophilic-fluorine route, now largely abandoned.","supply":"adequate","supplyNote":"Regional cyclotron networks (PETNET Solutions/Siemens, Cardinal Health, GE HealthCare, SOFIE, Jubilant Radiopharma) distribute unit doses across metropolitan areas; the 110-minute half-life is long enough for same-morning delivery, so supply is not dependent on a single site the way generator-based isotopes are.","chelators":[],"pairedWith":[],"since":1976},{"id":"ga-67","kind":"isotope","name":"Gallium-67","aka":["67Ga"],"tldr":"An older radioactive gallium tracer, given as a citrate injection, that lights up infections and some tumours over a scan taken a few days later; mostly replaced now by FDG PET but still used where PET is unavailable.","summary":"Gallium-67 decays by electron capture with a 3.26-day (78.3-hour) half-life, emitting a set of gamma rays (93, 185 and 300 keV) suited to planar gamma-camera and SPECT imaging. Complexed with citrate as 67Ga-citrate, it accumulates in inflammatory and infectious foci and in a range of tumours, historically including lymphoma, hepatoma and bronchogenic carcinoma, and was for decades the standard whole-body tumour and infection imaging agent before FDG PET became widely available.\n\nIt is produced on a cyclotron by proton bombardment of enriched zinc-68, the 68Zn(p,2n)67Ga reaction, and its multi-day half-life means imaging is typically performed 24-72 hours after injection to let background activity clear, at the cost of a comparatively high radiation burden and lower image resolution than modern PET agents.\n\nClinical use of 67Ga-citrate has declined sharply since the 2000s as FDG-PET/CT displaced it for lymphoma and most solid-tumour indications, and it now survives mainly as a second-line option for infection and inflammation imaging where PET access, FDG production or reimbursement pose barriers.","status":"historic","asOf":"2026-09-22","links":[{"label":"DailyMed/FDA label: Gallium Citrate Ga 67","url":"https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=5f670c12-cca5-4d73-8a88-241f753d1bc7"},{"label":"Nordion: gallium-67 fact sheet","url":"https://www.nordion.com/wp-content/uploads/2014/10/MI_Gallium-67_Canada.pdf"}],"tags":["gamma emitter","legacy tumour and infection imaging"],"related":[],"indications":["neuroendocrine"],"sections":[],"technologies":["spect","cyclotron-isotope-production"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"67Ga","element":"Gallium","massNumber":67,"halfLife":"3.26 days (78.3 hours)","emissions":["γ 93 keV (38%)","γ 185 keV (21%)","γ 300 keV (17%)"],"emissionClass":"gamma","use":"imaging","production":"Cyclotron: 68Zn(p,2n)67Ga on enriched zinc-68 target.","supply":"adequate","supplyNote":"Clinical demand has fallen substantially since FDG-PET/CT took over most oncology and infection-imaging indications previously served by gallium scans; remaining production is cyclotron-based and dispensed daily by commercial radiopharmacies.","chelators":[],"pairedWith":[],"since":1969},{"id":"ga-68","kind":"isotope","name":"Gallium-68","aka":["68Ga"],"tldr":"A radioactive metal with a one-hour lifetime that is eluted from a shielded generator or made on a cyclotron and attached to a molecule that finds tumours, giving a PET scan the same day.","summary":"Gallium-68 decays with a 67.7-minute half-life, mostly by positron emission, and is the diagnostic half of two of the most important theranostic pairs in oncology: 68Ga-DOTATATE/DOTATOC paired with 177Lu-DOTATATE for neuroendocrine tumours, and 68Ga-PSMA-11 paired with 177Lu-PSMA-617 or 225Ac-PSMA for prostate cancer.\n\nIt is traditionally produced by eluting a 68Ge/68Ga generator, where the 270.8-day parent 68Ge is fixed to a column and decays continuously; the daughter is washed off with dilute acid on demand. Commercial GMP generators (Eckert & Ziegler, IRE, ITG) top out at 1.85-3.7 GBq per elution, and lead times for new units have historically run to 18 months, which constrained the launch of PSMA PET in the late 2010s. A cyclotron route, direct 68Zn(p,n)68Ga irradiation of a liquid or solid target, produces roughly a curie per run against a generator's 40-50 mCi and has been promoted by the IAEA since a 2019 technical document and a 2020 coordinated research project as the way to relieve that bottleneck.\n\nBy the mid-2020s the practical supply picture had eased: Eckert & Ziegler expanded generator manufacturing capacity after a 2017 germanium shortage, and cyclotron-produced 68Ga (including for PSMA-11) is now used at large centres alongside the F-18-labelled PSMA alternatives (Pylarify, PSMA-1007, flotufolastat) that took share once generator lead times became a launch constraint.","status":"established","asOf":"2026-09-22","links":[{"label":"IAEA: cyclotron-based gallium-68 for cancer detection (2024)","url":"https://www.iaea.org/newscenter/news/alternatives-for-accessing-lifesaving-diagnostic-radioisotopes-cyclotron-based-gallium-68-for-cancer-detection"},{"label":"PMC: Current status of the production and supply of gallium-68","url":"https://pubmed.ncbi.nlm.nih.gov/32196363/"},{"label":"IAEA TE-2127: good management practices of cyclotron-based Ga-68 production","url":"https://www-pub.iaea.org/MTCD/publications/PDF/TE-2127web.pdf"},{"label":"Applied Radiation Oncology: nuclear medicine prepares for greater 68Ga demand (2021)","url":"https://www.appliedradiationoncology.com/articles/nuclear-medicine-prepares-for-greater-68ga-demand"}],"tags":["positron emitter","generator","theranostic pair"],"related":["ga68-dotatate","ga68-psma-11","illuccix","locametz","ge-68"],"indications":[],"sections":[],"technologies":["sstr-pet","psma-pet","pet","radionuclide-generators-kits","cyclotron-isotope-production"],"targets":[],"drugs":[],"companies":["eckert-ziegler","ire","isotopia","telix","novartis"],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"68Ga","element":"Gallium","massNumber":68,"halfLife":"67.7 minutes","emissions":["β+ 89% (max 1.90 MeV)","electron capture 11%","annihilation γ 511 keV"],"emissionClass":"positron","use":"imaging","production":"68Ge/68Ga generator (elution with dilute HCl) or cyclotron 68Zn(p,n)68Ga on enriched zinc-68 liquid or solid target.","supply":"adequate","supplyNote":"Generator lead times of up to 18 months and a 2017 germanium shortage constrained supply during the PSMA PET launch; expanded generator manufacturing (Eckert & Ziegler GalliaPharm/GeGant) and IAEA-promoted cyclotron production (roughly 1 Ci per run versus 40-50 mCi per generator elution) have since relieved the bottleneck.","chelators":["DOTA","NOTA","HBED-CC"],"pairedWith":["lu-177","ac-225"],"since":2016},{"id":"ge-68","kind":"isotope","name":"Germanium-68","aka":["68Ge","Ge-68"],"tldr":"The long-lived parent locked inside a gallium-68 generator. One loaded column can supply a year's worth of PET tracer doses for prostate cancer and neuroendocrine tumour scans, but the generators themselves have been expensive and slow to get.","summary":"Germanium-68 decays by electron capture with a 270.8-day (about 9-month) half-life, far too long to be imaged usefully itself; its entire clinical role is as the parent bound inside a 68Ge/68Ga generator column, decaying continuously to the 68-minute daughter gallium-68 that is eluted with dilute acid for use in PET tracers such as 68Ga-DOTATATE and 68Ga-PSMA-11. Because the parent's half-life is roughly 5,800 times the daughter's, a single generator loaded with germanium-68 supplies a fairly constant, though slowly declining, stream of gallium-68 for around a year before it needs replacing.\n\nGermanium-68 itself is made almost exclusively by high-energy proton bombardment of a gallium metal target enriched in the stable isotope gallium-69, via the 69Ga(p,2n)68Ge reaction; because commercial-scale generator loadings require tens of gigabecquerels of activity and the reaction needs proton energies of roughly 20-30 MeV over several days of irradiation at high beam current, only a small number of high-energy cyclotron and accelerator facilities worldwide can produce it (an alternative 66Zn(alpha,2n)68Ge route using alpha-particle beams exists but is less commonly used).\n\nThat narrow production base is why 68Ge/68Ga generator supply has repeatedly lagged clinical demand: GMP-grade generator lead times ran as long as 18 months in the years before the 2016-2020 approvals of gallium-68 DOTATATE and PSMA-11 PET agents, and a 2017 shortage of germanium feedstock further squeezed availability, prompting the IAEA in 2019-2020 to promote direct cyclotron production of gallium-68 (68Zn(p,n)68Ga) as a way to sidestep the germanium-68 bottleneck altogether rather than solve it. Manufacturers including Eckert & Ziegler subsequently expanded generator manufacturing capacity, and by the mid-2020s most large PET centres have access to either generator- or cyclotron-produced gallium-68, though the underlying germanium-68 production base remains concentrated in a handful of accelerator facilities.","status":"established","asOf":"2026-09-22","links":[{"label":"PMC: good practices for 68Ga radiopharmaceutical production (68Ge production section)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC9588110/"},{"label":"Wikipedia: gallium-68 generator (68Ge production routes)","url":"https://en.wikipedia.org/wiki/Gallium-68_generator"},{"label":"IAEA: new CRP on cyclotron-based gallium-68 (2020)","url":"https://www.iaea.org/newscenter/news/new-crp-production-of-cyclotron-based-gallium-68-radioisotope-and-related-radiopharmaceuticals-f22073"}],"tags":["generator parent","long-lived","supply bottleneck"],"related":["ga-68","ga68-dotatate","ga68-psma-11"],"indications":[],"sections":[],"technologies":["radionuclide-generators-kits","sstr-pet","psma-pet","cyclotron-isotope-production"],"targets":[],"drugs":[],"companies":["eckert-ziegler","ire","isotopia"],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"68Ge","element":"Germanium","massNumber":68,"halfLife":"270.8 days","emissions":["electron capture (decays to 68Ga)"],"emissionClass":"gamma","use":"imaging","production":"Cyclotron: 69Ga(p,2n)68Ge on gallium metal target enriched in gallium-69, requiring proton energies of roughly 20-30 MeV and multi-day, high-current irradiation; alternative 66Zn(alpha,2n)68Ge route with alpha-particle beams.","supply":"tight","supplyNote":"Production is concentrated at a small number of high-energy accelerator facilities because commercial generator loadings need irradiations of tens of thousands of microamp-hours; GMP generator lead times reached about 18 months before the PSMA PET launch, and a 2017 germanium feedstock shortage further tightened supply. IAEA-promoted direct cyclotron production of gallium-68 bypasses this bottleneck rather than resolving it.","chelators":[],"pairedWith":["ga-68"],"since":1960},{"id":"ho-166","kind":"isotope","name":"Holmium-166","aka":["166Ho","Ho-166"],"tldr":"A radioactive metal built into tiny beads that are injected into the artery feeding a liver tumour, where they lodge and irradiate it from close range. Unlike similar beads made with yttrium-90, these can also be seen clearly on a scan.","summary":"Holmium-166 poly-L-lactic acid (PLLA) microspheres (QuiremSpheres, QuiremScout) deliver radioembolisation to liver tumours much as yttrium-90 microspheres do, but 166Ho's shorter half-life (26.8 hours) concentrates over 90% of the dose within about 4 days, versus roughly 11 days for 90Y. Its beta spectrum has two main components near 1.77 MeV (48.7%) and 1.85 MeV (50.0%), with a mean tissue range around 2.2-2.5 mm and maximum around 8.7-11 mm, broadly comparable to 90Y.\n\nThe key practical advantage is imageability: 166Ho emits an 81 keV gamma photon (about 6.6-6.7% abundance) suitable for SPECT/CT, and holmium's paramagnetic properties also make the microspheres visible on MRI, so the same product used for a diagnostic 'scout' dose and the therapeutic dose can both be imaged directly, rather than relying on a technetium-99m-labelled surrogate as with 90Y (which requires a separate macroaggregated-albumin lung-shunt scan).\n\n166Ho microspheres are manufactured by first embedding stable holmium-165 in the PLLA polymer matrix, then neutron-activating the finished microspheres in a research reactor (165Ho(n,γ)166Ho); production has run at the BR2 reactor (Belgium) and the Maria reactor (Poland). As a single-manufacturer product (Quirem Medical, part of Terumo) tied to specific reactor irradiation slots, availability is narrower than for 90Y microspheres but has not been reported as a major bottleneck.","status":"approved","asOf":"2026-09-22","links":[{"label":"Holmium-166 Radioembolization: Current Status and Future Perspectives (Cancers, 2022)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC9626412/"},{"label":"NICE: QuiremSpheres for unresectable hepatocellular carcinoma","url":"https://www.nice.org.uk/guidance/ta985/chapter/2-Information-about-QuiremSpheres"},{"label":"Safety and efficacy of holmium-166 radioembolization in HCC - the HEPAR Primary study (J Nucl Med, 2022)","url":"https://jnm.snmjournals.org/content/jnumed/early/2022/05/19/jnumed.122.263823.full.pdf"}],"tags":["therapy","beta emitter","gamma emitter","radioembolisation","MRI-visible"],"related":["radioembolisation-tare","y-90","hcc","hcc-intermediate"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"166Ho","element":"Holmium","massNumber":166,"halfLife":"26.8 hours","emissions":["β− 1.77 MeV (48.7%) and 1.85 MeV (50.0%)","γ 81 keV (6.6-6.7%)"],"emissionClass":"beta-minus","use":"both","tissueRange":"Mean about 2.2-2.5 mm, maximum about 8.7-11 mm","production":"Reactor: neutron activation of stable holmium-165 already embedded in the finished PLLA microspheres, 165Ho(n,γ)166Ho.","supply":"adequate","supplyNote":"Single-manufacturer product (Quirem Medical/Terumo) irradiated at specific reactors (e.g. BR2 in Belgium, Maria in Poland); narrower supplier base than 90Y microspheres but not reported as a bottleneck.","chelators":[],"pairedWith":[]},{"id":"in-111","kind":"isotope","name":"Indium-111","aka":["111In"],"tldr":"A radioactive metal used, attached to octreotide, as the original scan for neuroendocrine tumours (Octreoscan) before gallium-68 PET took over, and still used to label white blood cells for infection imaging.","summary":"Indium-111 decays by electron capture to stable cadmium-111 with a 2.805-day half-life, emitting gamma photons suited to gamma-camera and SPECT imaging. For two decades it was the standard somatostatin-receptor imaging agent as 111In-pentetreotide (Octreoscan), used to select neuroendocrine tumour patients before peptide receptor radionuclide therapy, first with 90Y-labelled and later with 177Lu-labelled somatostatin analogues; SPECT-based Octreoscan has since been largely replaced by 68Ga- or 64Cu-DOTATATE PET, which has better resolution and quantification, but 111In-pentetreotide remains on label and in use where PET access is limited.\n\nIt is produced on a cyclotron by proton bombardment of an enriched cadmium target, either 112Cd(p,2n)111In or 111Cd(p,n)111In, the latter giving higher radionuclidic purity. Its 2.8-day half-life is long enough to ship internationally and to track slower-clearing tracers such as labelled leukocytes and antibody fragments, which is why it is also used for infection and inflammation imaging (111In-labelled white cells) and in some antibody biodistribution and dosimetry studies.","status":"established","asOf":"2026-09-22","links":[{"label":"FDA/DailyMed label: OctreoScan (indium In 111 pentetreotide)","url":"https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=93d8f3b2-1216-41dc-a63d-0e812b33891d"},{"label":"Wikipedia: indium-111 (production routes)","url":"https://en.wikipedia.org/wiki/Indium-111"}],"tags":["gamma emitter","legacy somatostatin imaging"],"related":["ga68-dotatate","lutathera"],"indications":["neuroendocrine"],"sections":[],"technologies":["spect","spect-ct","sstr-pet","cyclotron-isotope-production"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"111In","element":"Indium","massNumber":111,"halfLife":"2.805 days","emissions":["γ 171 keV (90%)","γ 245 keV (94%)","electron capture"],"emissionClass":"gamma","use":"imaging","production":"Cyclotron: 111Cd(p,n)111In (higher purity) or 112Cd(p,2n)111In on enriched cadmium targets.","supply":"adequate","supplyNote":"Cyclotron-produced at a moderate number of sites; demand has fallen substantially since 68Ga/64Cu-DOTATATE PET replaced 111In-pentetreotide SPECT as the preferred somatostatin-receptor imaging test.","chelators":["DTPA"],"pairedWith":["y-90","lu-177"],"since":1994},{"id":"i-123","kind":"isotope","name":"Iodine-123","aka":["123I"],"tldr":"A radioactive form of iodine that decays quickly and gives off gamma rays, used to take a picture of the thyroid or, attached to a nerve-tracing molecule, of tumours of the adrenal gland and nervous system, before deciding whether a therapeutic dose of iodine-131 makes sense.","summary":"Iodine-123 has a 13.2-hour half-life and decays by electron capture with a dominant 159 keV gamma emission well suited to gamma-camera and SPECT imaging. Its main clinical roles are thyroid uptake and scintigraphy, and as the diagnostic imaging partner to iobenguane (MIBG): 123I-MIBG scintigraphy stages neuroblastoma and phaeochromocytoma/paraganglioma before or alongside treatment with the therapeutic 131I-MIBG.\n\nIt is cyclotron-produced, never reactor-produced, most commonly via 124Xe(p,2n)123Cs, which decays through 123Xe to 123I, or via the (p,pn) channel on the same enriched xenon-124 target; a 123Te(p,n)123I route on enriched tellurium is also used. Both routes need a medium-energy cyclotron (20-30 MeV) and an expensive enriched target, which keeps 123I costlier and less universally available than reactor- or generator-based isotopes, and its 13-hour half-life limits how far it can be shipped before it has decayed away.\n\nBecause iodine's biochemistry is essentially identical across its isotopes, 123I plays the same diagnostic-before-therapeutic role for iodine and MIBG imaging that 68Ga and 18F play for peptide and small-molecule theranostics.","status":"established","asOf":"2026-09-22","links":[{"label":"PMC: perspective on production and quality control of iodine-123","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC12121839/"},{"label":"Radiopaedia: iodine-123","url":"https://radiopaedia.org/articles/iodine-123?lang=us"}],"tags":["gamma emitter","cyclotron","thyroid"],"related":["iobenguane-i-131","i131-mibg","i-124"],"indications":["neuroblastoma","pheochromocytoma-paraganglioma","thyroid"],"sections":[],"technologies":["spect","mibg-theranostics","cyclotron-isotope-production"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"123I","element":"Iodine","massNumber":123,"halfLife":"13.2 hours","emissions":["γ 159 keV (83%)","electron capture"],"emissionClass":"gamma","use":"imaging","production":"Cyclotron: 124Xe(p,2n)123Cs → 123Xe → 123I or 124Xe(p,pn)123Xe → 123I on enriched xenon-124 gas targets; alternatively 123Te(p,n)123I on enriched tellurium-123.","supply":"tight","supplyNote":"Requires a medium-energy (20-30 MeV) cyclotron and an expensive enriched xenon-124 or tellurium-123 target, so production is concentrated at a small number of sites worldwide; the 13.2-hour half-life limits shipping range, which has caused regional shortages.","chelators":[],"pairedWith":["i-131"],"since":1970},{"id":"i-124","kind":"isotope","name":"Iodine-124","aka":["124I"],"tldr":"A long-lived, PET-visible form of radioactive iodine used to map how a thyroid cancer takes up iodine over several days, so the dose of the treatment isotope, iodine-131, can be planned before it is given.","summary":"Iodine-124 decays with a 4.18-day half-life by a mix of electron capture and positron emission (positron abundance about 23%), giving it PET-imageable annihilation photons over a timescale of days rather than the minutes-to-hours typical of most PET isotopes. Because it shares iodine's biochemistry with the therapeutic isotope 131I, serial 124I PET/CT scans, typically at roughly 24 and 96-120 hours after a tracer dose, let physicists build a time-activity curve for each lesion and project the absorbed dose per unit of a subsequent 131I therapy activity, rather than relying on a fixed empiric dose.\n\nIts decay scheme is complex: only about 23% of decays produce a positron (mean energy 819 keV, giving relatively poor spatial resolution), while high-energy prompt gammas (603 keV and others) contaminate the coincidence signal, so scanners need isotope-specific calibration rather than the F-18 calibration used by default; published work has found this calibration factor can differ from F-18 by roughly ten percent.\n\nIt is cyclotron-produced by proton bombardment of enriched tellurium-124, 124Te(p,n)124I, chosen for high radionuclidic purity at proton energies below about 14 MeV, though yields from this reaction are comparatively low, and by the older 124Te(d,2n)124I route.","status":"emerging","asOf":"2026-09-22","links":[{"label":"PMC: I-124 imaging and dosimetry","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC5283715/"},{"label":"MDPI: radiochemistry, production and immunoPET imaging of iodine-124","url":"https://www.mdpi.com/1420-3049/26/2/414"}],"tags":["positron emitter","long-lived PET","pre-therapy dosimetry"],"related":["radioactive-iodine","i-123"],"indications":["thyroid"],"sections":[],"technologies":["pet","radioligand-dosimetry","cyclotron-isotope-production"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"124I","element":"Iodine","massNumber":124,"halfLife":"4.18 days","emissions":["β+ 23% (max ~2.14 MeV)","electron capture ~77%","γ 603 keV (61%)","annihilation γ 511 keV (46%)"],"emissionClass":"positron","use":"imaging","production":"Cyclotron: 124Te(p,n)124I on enriched tellurium-124 (proton energies below ~14 MeV for high radionuclidic purity); older 124Te(d,2n)124I route also used.","supply":"constrained","supplyNote":"Low reaction yield and the need for an expensive enriched tellurium-124 target mean 124I is produced at only a limited number of cyclotron centres, mostly for dosimetry research and thyroid-cancer pre-therapy planning rather than routine clinical stock.","chelators":[],"pairedWith":["i-131"],"since":1994},{"id":"i-131","kind":"isotope","name":"Iodine-131","aka":["131I","I-131","radioiodine"],"tldr":"A radioactive form of iodine. Because the thyroid gland naturally absorbs iodine, swallowing it lets the radiation destroy thyroid cells or thyroid cancer cells almost anywhere they have spread, with very little effect on the rest of the body.","summary":"Iodine-131 decays by beta emission with an associated gamma emission and a physical half-life of 8.02-8.04 days. Its principal beta emissions average around 190 keV with higher-energy components up to roughly 606 keV, and the dominant imaging gamma is 364.5 keV (about 81% abundance); roughly 90% of local irradiation from sodium iodide I-131 comes from the beta component and 10% from gamma, per the FDA label.\n\nBecause thyroid follicular cells and well-differentiated thyroid cancer retain the sodium/iodide symporter, oral 131I concentrates selectively in thyroid tissue, remnant tissue after thyroidectomy, and iodine-avid metastases, delivering an internal beta dose. It has been used for benign thyroid disease and differentiated thyroid cancer ablation for more than 70 years and remains a WHO essential medicine.\n\nCommercial 131I is produced in a nuclear reactor overwhelmingly by neutron activation of tellurium-130 (130Te(n,γ)131Te/131mTe, which beta-decays to 131I), recovered by dry or wet distillation; it can also be recovered as a uranium-235 fission product, though current suppliers do not routinely co-recover it that way. As a widely produced, long-established reactor product with many qualified suppliers, supply is generally adequate, though individual reactor outages can cause local shortages.","status":"approved","asOf":"2026-09-22","links":[{"label":"FDA label: Sodium Iodide I-131 Solution (therapeutic)","url":"https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/016517s016lbl.pdf"},{"label":"FDA label: Sodium Iodide I 131 Capsules (diagnostic)","url":"https://www.accessdata.fda.gov/drugsatfda_docs/label/2016/021305s041lbl.pdf"},{"label":"Medical Isotope Production and Utilization (NAS/NCBI, 2016)","url":"https://www.ncbi.nlm.nih.gov/books/NBK396163/"}],"tags":["therapy","beta emitter","gamma emitter"],"related":["radioactive-iodine","radioiodine-therapy","i131-mibg","iobenguane-i-131","thyroid","estimabl2","radioiodine-term"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"131I","element":"Iodine","massNumber":131,"halfLife":"8.02 days","emissions":["β (mean 191.6 keV, 89.9%; smaller components at 69.4 and 96.6 keV)","γ 364.5 keV (81.2%)","γ 637.0 keV (7.2%)","γ 284.3 keV (6.1%)"],"emissionClass":"beta-minus","use":"therapy","tissueRange":"A few millimetres (beta range)","production":"Reactor: neutron activation of tellurium-130, 130Te(n,γ)131Te (or 131mTe), which beta-decays to 131I; historically also recoverable as a 235U fission product.","supply":"adequate","supplyNote":"Long-established reactor product made by many qualified international suppliers via Te-130 activation; generally adequate, though reactor outages can cause transient regional shortages.","chelators":[],"pairedWith":["i-123","i-124"],"since":1946},{"id":"kr-81m","kind":"isotope","name":"Krypton-81m","aka":["81mKr","Kr-81m","krypton gas"],"tldr":"A radioactive gas that a patient simply breathes in and out while the camera runs. It decays in thirteen seconds, so the picture is of ventilation happening now rather than of particles left behind, and it has to be generated in the room from a parent that itself lasts only a few hours.","summary":"Krypton-81m is an inert gas with a 13-second physical half-life and a 190 keV gamma emission, eluted from an 81Rb/81mKr generator: rubidium-81, bound to a zirconium phosphate cation exchange resin, sits in equilibrium with its krypton daughter, and passing oxygen or air through the generator carries the gas to the patient. The patient inhales continuously through the acquisition, so the image is a steady-state map of where air is arriving, and because the activity vanishes between views the study can be repeated in as many projections as wanted with negligible dose.\n\nIts distinctive advantage is the 190 keV photon, well separated from technetium-99m's 140 keV, which means ventilation and perfusion can be acquired simultaneously rather than sequentially. The 2019 EANM V/Q SPECT guideline puts krypton alongside Technegas as preferred over Tc-99m DTPA aerosol in patients with COPD, where a wet aerosol deposits centrally, and one comparative review argues krypton is the better ventilation tracer for its penetration and absence of hot spots, cautioning against replacing it with Technegas in severe COPD. The counterweight is that in badly obstructed lungs the time to reach steady state may be too long.\n\nAvailability is the whole problem. Rubidium-81 is cyclotron-made, principally by the 82Kr(p,2n)81Rb reaction, and has a half-life of about 4.6 hours, so a generator has to be delivered to the hospital daily from a nearby cyclotron. That economics confined krypton to a handful of countries: Kr-81m/Tc-99m V/Q imaging was once, by one account, the second most performed nuclear medicine procedure in the United Kingdom after bone scanning, and a generator remains licensed in Denmark by Rigshospitalet's own cyclotron. In the United States GE Healthcare's MPI Krypton 81m generator (NDA 018088, approved 1980) was withdrawn effective 7 December 2007, and US commercial availability had already ended years earlier.","status":"historic","asOf":"2026-09-23","links":[{"label":"EANM 2019 guideline for ventilation/perfusion SPECT (krypton and Technegas preferred over DTPA in COPD; 13 s half-life, 190 keV, simultaneous acquisition with Tc-99m)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC6813289/"},{"label":"Comparative review: krypton-81m versus Technegas for ventilation imaging in COPD","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC7808361/"},{"label":"IAEA evaluated nuclear data for 81Rb production, 82Kr(p,2n)81Rb, parent half-life 4.572 h","url":"http://arxiv.org/pdf/2006.03125"},{"label":"Ventilation studies with krypton-81m: continuous-flow elution and repeated projections","url":"https://pubmed.ncbi.nlm.nih.gov/542943/"}],"tags":["ventilation","V/Q","generator","gas"],"related":["technegas","tc-99m-maa","tc-99m","pulmonary-embolism-vq","split-function-lung-perfusion"],"indications":["pulmonary-embolism-vq"],"sections":[],"technologies":["spect","radionuclide-generators-kits"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"81mKr","element":"Krypton","massNumber":81,"halfLife":"13 seconds","emissions":["γ 190 keV"],"emissionClass":"gamma","use":"imaging","production":"Generator: decay of cyclotron-produced rubidium-81 (half-life about 4.6 hours) adsorbed on zirconium phosphate resin, made principally by the 82Kr(p,2n)81Rb reaction; the gas is eluted by a continuous flow of oxygen or air and inhaled directly.","supply":"constrained","supplyNote":"The parent's 4.6-hour half-life forces daily delivery from a cyclotron within a few hours' reach, which is why use is confined to a few centres and countries. The only US product, GE Healthcare's MPI Krypton 81m generator (NDA 018088, 1980), was formally withdrawn effective 7 December 2007. A generator authorisation is held in Denmark by the cyclotron and radiochemistry unit at Rigshospitalet, Copenhagen.","chelators":[],"pairedWith":["tc-99m"]},{"id":"pb-212","kind":"isotope","name":"Lead-212","aka":["212Pb","Pb-212"],"tldr":"A radioactive metal that, once inside the body, turns itself into a much more damaging particle-emitter over the following hours. It is being explored as a way to deliver strong, short-range radiation without needing the rarer isotopes used in similar treatments.","summary":"Lead-212 is itself a beta emitter, but it functions in practice as an in vivo generator of alpha radiation: it decays (half-life 10.64 hours) to bismuth-212 (half-life about 61 minutes), which then decays either directly by alpha emission (to thallium-208) or by a further beta decay to the pure alpha emitter polonium-212. A member of the thorium-232/232U decay series, 212Pb is drawn from generators loaded with its longer-lived parents radium-224 (half-life 3.63 days) or thorium-228 (half-life about 1.9 years).\n\nIts 10.6-hour half-life is long enough to synthesise and ship a labelled radiopharmaceutical but short enough to limit prolonged radiation exposure, and it uses conventional chelation chemistry (unlike some other alpha emitters). 212Pb-DOTAMTATE (AlphaMedix) and other 212Pb-labelled somatostatin and PSMA-targeting agents are in early clinical trials.\n\nUnlike actinium-225, the feedstock chain for 212Pb (natural thorium-232/uranium-232 decay) is not considered scarce: Perspective Therapeutics states its proprietary 224Ra/212Pb generator system and a long-term US DOE supply contract for 228Th could support over 100,000 doses per year, and Orano Med, RadioMedix/Thor Medical and others are commercialising 228Th-based 212Pb generators. Some reviews describe 212Pb supply as having moved from a major constraint to a largely solved production problem, though clinical-scale, GMP-qualified generator throughput is still being industrialised.","status":"phase-2","asOf":"2026-09-22","links":[{"label":"212Pb: Production Approaches and Targeted Therapy Applications (Pharmaceuticals, 2022)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC8777968/"},{"label":"Perspective Therapeutics: Manufacturing & Logistics (VMT-α-GEN Pb-212 generator)","url":"https://perspectivetherapeutics.com/technology/manufacturing-logistics"},{"label":"DOE Isotope Program: Availability of radium-224/lead-212 generators","url":"https://www.isotopes.gov/node/123"},{"label":"Lead radionuclides for theranostic applications in nuclear medicine (PMC, 2026)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC12775822/"}],"tags":["therapy","alpha emitter","in vivo generator"],"related":["alphamedix","alphamedix-02","targeted-alpha-therapy","ra-224","bi-213","idea-reg-alpha-emitter-portfolio","perspective-therapeutics"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"212Pb","element":"Lead","massNumber":212,"halfLife":"10.64 hours","emissions":["β− 0.57 MeV (to 212Bi)","in vivo daughter 212Bi decays 35.9% by α to 208Tl, 64.1% by β− to 212Po","212Po α 8.78 MeV (from 212Bi decay)"],"emissionClass":"mixed","use":"therapy","tissueRange":"Sub-millimetre (alpha range from in-vivo-generated 212Bi/212Po)","production":"Generator: eluted from 224Ra or 228Th sources (228Th itself recovered from decaying 232U stocks), via 220Rn emanation or column separation.","supply":"emerging","supplyNote":"Feedstock (natural thorium-232/232U decay) is not scarce. Perspective Therapeutics reports a long-term DOE supply contract for 228Th and generator capacity aimed at over 100,000 doses/year; Orano Med, Telix and RadioMedix/Thor Medical are also commercialising 228Th/224Ra-based 212Pb generators, but clinical-scale GMP throughput is still being built out.","chelators":["DOTAM","DOTAMTATE-type macrocycles"],"pairedWith":["ga-68"]},{"id":"lu-177","kind":"isotope","name":"Lutetium-177","aka":["177Lu","Lu-177"],"tldr":"A radioactive metal that gives off short-range radiation. Attached to a molecule that sticks to a tumour, it irradiates the tumour from the inside while sparing most healthy tissue.","summary":"Lutetium-177 is the workhorse therapeutic radionuclide of the theranostic era, carried by DOTATATE (Lutathera, neuroendocrine tumours) and PSMA-617 (Pluvicto, prostate cancer). Its 6.65-day half-life and roughly 0.5-2 mm beta range let it be shipped internationally and deliver a dose that matches small-to-medium tumour deposits.\n\nIts 208 keV gamma emission is imageable, so the same injection that treats the patient can be used for post-therapy SPECT and dosimetry. It can be made carrier-added by direct neutron capture on 176Lu, or no-carrier-added (higher specific activity) via 176Yb(n,γ)177Yb, which decays to 177Lu; the latter avoids the long-lived 177mLu impurity but needs scarce enriched 176Yb.\n\nDemand rose sharply after Pluvicto's 2022 approval, straining the small number of high-flux research reactors (BR2, HFR, Maria, SAFARI-1 and others) and the Russian-dominated supply of enriched ytterbium-176. Shortages in 2022-2023 delayed some Pluvicto doses; new capacity (Bruce Power/Isogen in Canadian CANDU reactors, SHINE's accelerator route) has since expanded supply.","status":"approved","asOf":"2026-09-22","links":[{"label":"Challenges and future options for the production of lutetium-177 (EJNMMI Radiopharm Chem, 2021)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC8241800/"},{"label":"FDA label: Pluvicto (lutetium Lu 177 vipivotide tetraxetan)","url":"https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/215833s000lbl.pdf"},{"label":"OECD-NEA: Current trends in the supply and utilisation of medical radioisotopes (2025)","url":"https://www.oecd-nea.org/upload/docs/application/pdf/2025-10/7743_medical_radioisotopes_supply_rev.pdf"}],"tags":["therapy","beta emitter"],"related":["pluvicto","lutathera","prrt","lu177-radioligand-therapy","therapy-isotope-supply-chain"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"177Lu","element":"Lutetium","massNumber":177,"halfLife":"6.65 days","emissions":["β− 497 keV maximum (mean 134 keV)","γ 113 keV (6.2%)","γ 208 keV (10.4%)"],"emissionClass":"beta-minus","use":"therapy","tissueRange":"Up to about 2 mm, mean roughly 0.5-0.7 mm","production":"Reactor. Non-carrier-added via 176Yb(n,γ)177Yb, which beta-decays to 177Lu; or carrier-added via direct 176Lu(n,γ)177Lu (co-produces long-lived 177mLu).","supply":"tight","supplyNote":"Demand rose sharply after Pluvicto's approval. Reactor neutron-flux capacity and the scarcity of enriched 176Yb (historically mostly from Russian calutrons) are the binding constraints; new capacity from Bruce Power/Isogen (Canada) and accelerator routes (SHINE) is scaling up.","chelators":["DOTA","DOTAGA"],"pairedWith":["ga-68"],"since":2018},{"id":"mo-99","kind":"isotope","name":"Molybdenum-99","aka":["99Mo","Mo-99"],"tldr":"The parent isotope shipped worldwide to make technetium-99m, the gamma-ray tracer used in the majority of nuclear medicine scans. It is made in a handful of ageing research reactors, and when one breaks down, scans get delayed or cancelled.","summary":"Molybdenum-99 decays with a 65.94-hour (about 2.75-day) half-life to technetium-99m, and its whole purpose in the supply chain is to act as a transportable parent: its longer half-life lets bulk 99Mo be irradiated, processed and shipped internationally to radiopharmacies, which then load it into 99Mo/99mTc generators and elute the six-hour daughter locally, on demand, for the roughly tens of millions of Tc-99m scans performed worldwide each year.\n\nHistorically some 90-95% of global 99Mo came from just five ageing research reactors, three in Europe (BR2 in Belgium, HFR in the Netherlands, and the now-closed OSIRIS in France), one in Canada (the now-closed NRU) and one in South Africa (SAFARI-1); by the OECD/NEA's 2025 accounting the surviving fleet, including BR2 and HFR, remains dominated by reactors that were not designed for continuous isotope production and were commissioned in the mid-20th century, so unplanned outages are a recurring risk: an October 2024 structural fault forced an unplanned shutdown of the HFR, which combined with scheduled maintenance elsewhere to worsen shortages of both 99Mo and 99mTc that winter.\n\nThe other defining event of the last fifteen years has been the conversion from highly enriched uranium (HEU, historically 45-98% 235U) fission targets to low-enriched uranium (LEU, under 20% 235U) for non-proliferation reasons: Curium's Netherlands processing facility completed conversion in January 2018, and IRE (Belgium) completed its conversion in March 2023, after which the OECD/NEA estimated that more than 90% of global bulk 99Mo production capacity came from non-HEU sources. LEU targets are less efficient and generate more waste per curie produced, and the industry's underlying economic problem, according to repeated OECD/NEA studies, is that irradiation and processing prices have historically been too low to fund the reactor and processing capacity replacement the ageing fleet needs; the 2010 NEA economic study estimated irradiation-service prices would need to rise by up to roughly a factor of nine to be sustainable. New non-fission routes are diversifying supply: NorthStar's RadioGenix System, which produces 99Mo by neutron activation of enriched or natural molybdenum targets rather than uranium fission, reached commercial scale in the 2020s (though NorthStar separately announced in 2023 a temporary halt to one production line), and Australia's ANSTO and South Africa's NTP Radioisotopes remain major LEU-fission suppliers outside the historic European/Canadian core.","status":"established","asOf":"2026-09-22","links":[{"label":"OECD/NEA: current trends in the supply and utilisation of medical radioisotopes (2025)","url":"https://www.oecd-nea.org/upload/docs/application/pdf/2025-10/7743_medical_radioisotopes_supply_rev.pdf"},{"label":"OECD/NEA: the security of supply of medical radioisotopes, 2023-2027 demand and capacity projections","url":"https://www.oecd-nea.org/upload/docs/application/pdf/2023-10/nea_ndc_r_2023_1.pdf"},{"label":"OECD/NEA: an economic study of the molybdenum-99 supply chain","url":"https://www.oecd-nea.org/med-radio/reports/MO-99.pdf"}],"tags":["beta emitter","generator parent","reactor supply chain","ageing infrastructure"],"related":["tc-99m","technetium-sulfur-colloid","tilmanocept-tc99m"],"indications":[],"sections":[],"technologies":["research-reactor-isotope-production","radionuclide-generators-kits","therapy-isotope-supply-chain","spect"],"targets":[],"drugs":[],"companies":["curium","ire","ansto","ntp-radioisotopes","northstar-medical-radioisotopes","nordion"],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"99Mo","element":"Molybdenum","massNumber":99,"halfLife":"65.94 hours (2.75 days)","emissions":["β− (multiple transitions, max ~1.36 MeV)","γ (from 99mTc daughter, 140.5 keV)"],"emissionClass":"beta-minus","use":"imaging","production":"Reactor: fission of highly enriched or low-enriched uranium-235 targets, or neutron activation of enriched/natural molybdenum-98, 98Mo(n,γ)99Mo (used by NorthStar's RadioGenix System).","supply":"constrained","supplyNote":"Roughly 95% of global supply still comes from a handful of ageing research reactors (BR2, HFR, LVR-15, Maria, SAFARI-1 and others); the October 2024 unplanned HFR shutdown combined with scheduled maintenance elsewhere to cause supply strain, and the underlying OECD/NEA-documented problem is decades of underinvestment against a fleet that was not designed for continuous production. HEU-to-LEU target conversion is essentially complete (Curium, January 2018; IRE, March 2023; more than 90% of global bulk 99Mo from non-HEU sources by 2023) but LEU targets are less efficient.","chelators":[],"pairedWith":["tc-99m"],"since":1958},{"id":"n-13","kind":"isotope","name":"Nitrogen-13","aka":["13N"],"tldr":"A radioactive gas-forming isotope with a ten-minute lifetime, turned into ammonia and injected to map blood flow to the heart muscle on a PET scan.","summary":"Nitrogen-13 decays by pure positron emission with a 9.97-minute half-life. Its main clinical use is as ammonia N-13 injection, an FDA-approved PET myocardial perfusion agent (initial US approval 2007) used at rest and under pharmacological stress to evaluate suspected or existing coronary artery disease; it clears the blood with a biological half-life of under three minutes and is trapped in viable myocardium as glutamine.\n\nIt is made on a cyclotron via the 16O(p,α)13N reaction, typically by irradiating a dilute ethanol-in-water target, with the proton beam degraded to avoid co-producing oxygen-15 by the competing 16O(p,pn)15O channel. Because the ten-minute half-life is even shorter than fluorine-18's, N-13 ammonia must be made on site or very close to the scanner, which historically limited it to centres with an in-house cyclotron; compact superconducting mini-cyclotrons introduced in the 2010s and 2020s have made single-site N-13 ammonia production more practical for community cardiac PET programmes.\n\nAlongside 82Rb and 15O-water, 13N-ammonia is one of only a small number of PET perfusion tracers, and one of only two (with 82Rb) that carry FDA approval for that indication in the United States.","status":"approved","asOf":"2026-09-22","links":[{"label":"FDA label: Ammonia N 13 Injection (initial approval 2007)","url":"https://www.accessdata.fda.gov/drugsatfda_docs/label/2011/022119s001lbl.pdf"},{"label":"PMC: reliable production of large quantities of [13N]ammonia","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC10254488/"}],"tags":["positron emitter","ultra-short-lived","cardiac perfusion"],"related":[],"indications":[],"sections":[],"technologies":["pet","cyclotron-isotope-production"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"13N","element":"Nitrogen","massNumber":13,"halfLife":"9.97 minutes","emissions":["β+ 100% (max 1.19 MeV)","annihilation γ 511 keV"],"emissionClass":"positron","use":"imaging","production":"Cyclotron: 16O(p,α)13N, typically on a dilute ethanol-in-water liquid target, with proton energy degraded to suppress the competing 16O(p,pn)15O reaction.","supply":"research-only","supplyNote":"The 9.97-minute half-life requires production essentially at the scanner; compact on-site mini-cyclotrons have widened access beyond large academic centres but supply remains site-by-site rather than distributed.","chelators":[],"pairedWith":[],"since":1970},{"id":"o-15","kind":"isotope","name":"Oxygen-15","aka":["15O"],"tldr":"A radioactive form of oxygen with a two-minute lifetime, made into water and injected to measure blood flow to the brain or heart; used almost exclusively in research because it decays too fast for routine hospital use in the US.","summary":"Oxygen-15 has the shortest half-life of any radionuclide used in PET, 122 seconds (about two minutes), and decays by pure positron emission. Labelled as [15O]water, it diffuses freely across cell membranes and its uptake is not confounded by metabolism, which makes it the physics gold standard for quantifying regional cerebral or myocardial blood flow; the very short half-life also allows repeat rest and stress or activation scans in the same session only 10-15 minutes apart, with a very low cumulative radiation dose.\n\nProduction requires an on-site cyclotron: nitrogen gas is bombarded with deuterons, 14N(d,n)15O, to give [15O]oxygen gas, which is then reacted over a heated palladium catalyst to form [15O]water vapour that is dissolved into saline for injection. Because a scan can only happen within a couple of minutes' walk of the cyclotron, [15O]water PET is confined to a small number of specialised academic centres worldwide.\n\n[15O]water PET myocardial and cerebral blood flow imaging is clinically approved and reimbursed in a number of European countries but, as of the mid-2020s, has not received FDA approval for routine US clinical use, so its US role remains research and investigational protocols rather than everyday practice.","status":"emerging","asOf":"2026-09-22","links":[{"label":"PMC: EANM procedural guidelines for PET/CT quantitative myocardial perfusion (O-15/N-13/Rb-82/F-18-flurpiridaz comparison table)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC7603916/"},{"label":"PMC: frugal and translatable [15O]O2 production for human research","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC11083888/"}],"tags":["positron emitter","shortest-lived PET isotope","cerebral blood flow"],"related":[],"indications":[],"sections":[],"technologies":["pet","cyclotron-isotope-production"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"15O","element":"Oxygen","massNumber":15,"halfLife":"122 seconds (about 2 minutes)","emissions":["β+ 100% (mean energy ~735 keV)","annihilation γ 511 keV"],"emissionClass":"positron","use":"imaging","production":"Cyclotron: 14N(d,n)15O on nitrogen gas target, converted to [15O]water over a heated palladium catalyst; 15N(p,n)15O and 16O(p,pn)15O are alternative routes.","supply":"research-only","supplyNote":"The 122-second half-life confines use to sites with an on-site cyclotron directly adjacent to the scanner; not FDA-approved for routine US clinical use as of the mid-2020s, though it is approved and reimbursed in parts of Europe.","chelators":[],"pairedWith":[],"since":1970},{"id":"p-32","kind":"isotope","name":"Phosphorus-32","aka":["32P","P-32"],"tldr":"A radioactive form of phosphorus, one of the oldest radioactive treatments in medicine. Because the body's cells constantly use phosphorus, it can be used to treat certain blood disorders or, injected directly into a body cavity, to control fluid build-up caused by cancer.","summary":"Phosphorus-32 decays purely by beta-minus emission (no gamma) with a half-life of 14.27-14.29 days, releasing 1.71 MeV of decay energy with an average beta energy of about 0.695 MeV, to stable sulfur-32. It has no gamma component, so it cannot be imaged with a gamma camera, and is entirely unsuitable for a diagnostic pairing.\n\nAs inorganic sodium phosphate, 32P has been used since 1939 to treat polycythaemia vera and other myeloproliferative disorders, where rapidly dividing marrow cells take up phosphate; as 32P-chromic phosphate colloid, it has been instilled directly into the peritoneal or pleural cavity to palliate malignant ascites or effusions, since colloidal particles are largely retained locally and irradiate the serosal surface. It is one of the oldest therapeutic radionuclides in clinical use and is classified by IARC as carcinogenic to humans (Group 1) based on its therapeutic use.\n\n32P is made in a reactor, most commonly by fast-neutron irradiation of sulfur-32 via the 32S(n,p)32P reaction (chosen because it avoids diluting the product with large amounts of inactive phosphorus), or alternatively by thermal-neutron capture on phosphorus-31, 31P(n,γ)32P. Because of its short half-life it cannot be stockpiled and must be used soon after production, but as a simple, long-established reactor product it is not considered supply-constrained.","status":"approved","asOf":"2026-09-22","links":[{"label":"Phosphorus-32 - isotopic data and properties","url":"https://www.chemlin.org/isotope/phosphorus-32"},{"label":"NCBI: X- and gamma-radiation (phosphorus-32 clinical background)","url":"https://www.ncbi.nlm.nih.gov/books/NBK304365/"},{"label":"PubChem: Phosphorus, radioactive (phosphorus-32 compound summary)","url":"https://pubchem.ncbi.nlm.nih.gov/compound/Phosphorus-Radioisotopes"}],"tags":["therapy","pure beta emitter","historic"],"related":["phosphorus-32","bone-metastases"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"32P","element":"Phosphorus","massNumber":32,"halfLife":"14.27-14.29 days","emissions":["β− average 0.695 MeV, maximum 1.71 MeV (100%, no gamma)"],"emissionClass":"beta-minus","use":"therapy","tissueRange":"Up to about 8 mm (beta range in tissue)","production":"Reactor: fast-neutron irradiation of sulfur-32, 32S(n,p)32P; or thermal-neutron capture on phosphorus-31, 31P(n,γ)32P.","supply":"adequate","supplyNote":"Simple, long-established reactor product; short half-life means it cannot be stockpiled and must be used soon after irradiation, but production is not considered constrained.","chelators":[],"pairedWith":[],"since":1939},{"id":"ra-223","kind":"isotope","name":"Radium-223","aka":["223Ra","Ra-223"],"tldr":"A radioactive form of the mineral radium that behaves like calcium and settles into bone. It gives off very short-range, high-energy particles that damage cancer growing in bone while barely reaching the healthy marrow next to it.","summary":"Radium-223 dichloride (Xofigo) is a calcium mimetic that concentrates in areas of increased bone turnover, such as osteoblastic bone metastases. It decays through a six-stage chain to stable lead-207, emitting predominantly alpha particles (95.3% of emitted energy), with small beta (3.6%) and gamma (1.1%) contributions from itself and its short-lived daughters (polonium-215, lead-211, bismuth-211, thallium-207).\n\nThe alpha range is under 100 micrometres in tissue (maximum about 6.2 cm in air), so the dose is deposited within roughly the width of a few cells of the bone surface, largely sparing the adjacent marrow. It was the first alpha-emitting radiopharmaceutical to gain FDA and EMA approval, on the strength of the ALSYMPCA trial's overall-survival benefit in metastatic castration-resistant prostate cancer with symptomatic bone metastases and no known visceral disease.\n\nRa-223 is obtained from a generator chain rooted in actinium-227 (itself made by neutron irradiation of radium-226 in a reactor); Ac-227 beta-decays to thorium-227, which alpha-decays to Ra-223. Commercial-scale 223Ra is available from Bayer's own supply chain and, more broadly, ORNL, PNNL and Rosatom hold production capability; a 2025 review (the PSI-led 'Alpha Atlas') judged that, unlike most other alpha emitters, 223Ra supply is adequate to global demand and no near-term shortage is expected.","status":"approved","asOf":"2026-09-22","links":[{"label":"FDA label: Xofigo (radium Ra 223 dichloride)","url":"https://www.accessdata.fda.gov/drugsatfda_docs/label/2013/203971lbl.pdf"},{"label":"Radium-223 mechanism of action (Nature Reviews Urology, 2019)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC7515774/"},{"label":"Production and supply of alpha particle emitting radionuclides for TAT (JNM, 2021)","url":"https://jnm.snmjournals.org/content/jnumed/early/2021/07/22/jnumed.120.261016.full.pdf"},{"label":"Alpha Atlas: mapping global production of alpha-emitting radionuclides for TAT (PSI, 2025)","url":"https://www.dora.lib4ri.ch/psi/islandora/object/psi:68199/datastream/PDF/Tosato-2025-Alpha_Atlas-(published_version).pdf"}],"tags":["therapy","alpha emitter","bone-seeking"],"related":["radium-223","alsympca","paper-alsympca-radium-223-nejm-2013","bone-metastases","th-227","targeted-alpha-therapy"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"223Ra","element":"Radium","massNumber":223,"halfLife":"11.4 days","emissions":["α (95.3% of emitted energy, range 5-7.5 MeV)","β− (3.6%, average 0.445 and 0.492 MeV)","γ (1.1%, 0.01-1.27 MeV range)"],"emissionClass":"alpha","use":"therapy","tissueRange":"Under 100 micrometres in tissue; up to 6.2 cm in air","production":"Generator chain from reactor-made actinium-227 (226Ra(n,γ)227Ra → β− → 227Ac), which beta-decays to 227Th, which alpha-decays to 223Ra.","supply":"adequate","supplyNote":"223Ra is judged adequately supplied worldwide; Bayer is the primary commercial supplier, with ORNL, PNNL and Rosatom also holding production capability for 223Ra and its 227Th parent.","chelators":[],"pairedWith":[],"since":2013},{"id":"ra-224","kind":"isotope","name":"Radium-224","aka":["224Ra","Ra-224"],"tldr":"A radioactive form of radium used mainly as a feedstock: it is loaded into a small on-site generator so that hospitals and manufacturers can draw off a different, more widely used radioactive metal (lead-212) whenever they need it.","summary":"Radium-224 decays by alpha emission with a half-life of 3.63 days, part of the thorium-232 decay series. Including its full decay chain through radon-220, polonium-216, lead-212, bismuth-212 and either polonium-212 or thallium-208 down to stable lead-208, a single 224Ra decay ultimately yields a cumulative 400% alpha and 200% beta emission (an average alpha energy of about 6.75 MeV per decay in the chain).\n\nIn current practice, 224Ra is used less as a therapeutic agent in its own right than as the loaded parent of a radionuclide generator: it is retained on a cation-exchange or similar column, from which the short-lived gaseous daughter radon-220 emanates and decays to lead-212, which is then eluted for radiolabelling (the DOE's Radium-224/Lead-212/Bismuth-212 generator product). Some experimental 'dual targeting' constructs have also used 224Ra directly, exploiting the fact that three of its four chain alpha particles decay within about 400 micrometres of the original 224Ra atom, while the longer-lived 212Pb daughter can diffuse further before delivering its own alpha dose.\n\n224Ra is obtained from the decay of thorium-228 (half-life about 1.9 years), which is itself recovered from decaying stocks of uranium-232; the DOE Isotope Program has supplied 224Ra/212Pb/212Bi generators (routinely available in batches up to about 16 mCi, ordered 8-10 weeks in advance) since 2015, drawing on thorium-228 separated at Oak Ridge National Laboratory.","status":"phase-1","asOf":"2026-09-22","links":[{"label":"DOE Isotope Program: Radium-224/Lead-212/Bismuth-212 Generator Product Information","url":"https://isotopes.gov/sites/default/files/2024-11/Radium-224-Lead-212-Bismuth-212%20Generator%20Product%20Information%20.pdf"},{"label":"Dual targeting with 224Ra/212Pb-conjugates for cancer therapy (PMC, 2023)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC9887039/"},{"label":"PRISMAP: 224Ra radionuclide portfolio page","url":"https://www.prismap.eu/radionuclides/portfolio/224Ra/"}],"tags":["therapy","alpha emitter","generator parent","research-only"],"related":["pb-212","targeted-alpha-therapy"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"224Ra","element":"Radium","massNumber":224,"halfLife":"3.63 days","emissions":["α 5.685 and 5.449 MeV (224Ra itself)","full decay chain to stable 208Pb: cumulative 400% α, 200% β− per 224Ra decay"],"emissionClass":"alpha","use":"therapy","tissueRange":"About 400 micrometres for the near-immediate chain alpha particles; longer for the diffusing 212Pb daughter","production":"Decay of parent thorium-228 (itself recovered from decaying uranium-232 stocks); loaded onto generator columns from which 224Ra or its daughter 212Pb can be eluted.","supply":"research-only","supplyNote":"Supplied by the DOE Isotope Program as 224Ra/212Pb/212Bi generators (batches up to about 16 mCi, order lead time 8-10 weeks), sourced from thorium-228 separated from decaying uranium-232 stocks at Oak Ridge National Laboratory.","chelators":[],"pairedWith":[]},{"id":"re-188","kind":"isotope","name":"Rhenium-188","aka":["188Re","Re-188"],"tldr":"A high-energy radioactive metal that a hospital can produce on demand from a small on-site generator, similar to how a common medical imaging isotope is made, rather than needing to import it. It is used for hard-to-reach tumours, including liver cancer.","summary":"Rhenium-188 is a high-energy beta emitter (maximum energies of 2.12 MeV, 71.1% abundance, and 1.96 MeV, 25.6%; mean beta energy around 763-784 keV) with a short 16.9-17.0 hour physical half-life and a co-emitted 155 keV gamma (about 15% abundance) that permits gamma-camera imaging, biodistribution and dosimetry studies -- chemically and logistically analogous to technetium-99m.\n\nIts key practical feature is on-demand generator production: 188Re is eluted as carrier-free sodium perrhenate from a tungsten-188/rhenium-188 generator, in which the long-lived parent 188W (half-life 69.4 days) is fixed on an alumina column, much like a molybdenum-99/technetium-99m generator. A single generator can supply daily eluted doses for around six months to a year, making 188Re one of the few therapeutic isotopes that hospitals in resource-limited settings can access without importing short-lived material.\n\n188W itself is made in a high-flux reactor by double neutron capture on enriched tungsten-186, 186W(n,γ)187W(n,γ)188W, at facilities such as the High Flux Isotope Reactor (Oak Ridge, USA), the SM-3 reactor (Russia) and BR2 (Belgium). 188Re-labelled agents (e.g. 188Re-HDD/lipiodol for hepatocellular carcinoma, 188Re-labelled bone and vascular agents) have been used mainly in investigator-led studies and in India and other countries where the generator route lowers cost, but none has reached FDA or EMA approval.","status":"phase-2","asOf":"2026-09-22","links":[{"label":"Rhenium-188 Production in Hospitals, by W-188/Re-188 Generator (PMC, 2013)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC3638650/"},{"label":"Fundamentals of Rhenium-188 Radiopharmaceutical Chemistry (Pharmaceutics, 2023)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC9921938/"},{"label":"Rhenium-188 Labeled Radiopharmaceuticals: Current Clinical Applications (Front Chem, 2019)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC6587137/"}],"tags":["therapy","beta emitter","gamma emitter","generator-produced"],"related":["hcc","radionuclide-generators-kits","bone-metastases"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"188Re","element":"Rhenium","massNumber":188,"halfLife":"16.9-17.0 hours","emissions":["β− 2.12 MeV maximum (71.1%)","β− 1.96 MeV maximum (25.6%)","γ 155 keV (~15%)"],"emissionClass":"beta-minus","use":"therapy","tissueRange":"Mean about 3.1 mm, maximum about 10-11 mm","production":"Generator: eluted as carrier-free sodium perrhenate from a tungsten-188/rhenium-188 generator; 188W made in a reactor by double neutron capture on enriched 186W, 186W(n,γ)187W(n,γ)188W.","supply":"adequate","supplyNote":"Generator-based, on-demand production keeps 188Re accessible without importing short-lived material; the 69.4-day 188W parent lets one generator supply doses for roughly 6-12 months. 188W production is concentrated at a small number of high-flux reactors (HFIR in the US, SM-3 in Russia, BR2 in Belgium).","chelators":[],"pairedWith":["tc-99m"]},{"id":"rb-82","kind":"isotope","name":"Rubidium-82","aka":["82Rb"],"tldr":"A radioactive potassium look-alike that lasts only about 75 seconds, delivered straight from a bedside generator into a vein, used to check blood flow to the heart without needing a cyclotron on site.","summary":"Rubidium-82 decays with a physical half-life of about 76 seconds, essentially entirely by positron emission, and behaves biologically as a potassium analogue that is extracted by viable myocardium in proportion to blood flow. Because the half-life is far too short to survive transport from a cyclotron, it is instead produced continuously by a strontium-82/rubidium-82 generator: the roughly 25-day parent 82Sr is bound to a column and the daughter is eluted with saline directly into an automated infusion system at the point of injection.\n\nAlongside 13N-ammonia it is one of only two PET myocardial perfusion tracers with FDA approval in the United States (marketed as CardioGen-82, and successor generator products), and its extremely short half-life allows a full rest-and-pharmacologic-stress study to be completed in around 20-30 minutes with very high patient throughput, since a decayed dose clears within minutes and cannot be reused. Because trace amounts of the parent 82Sr and the contaminant 85Sr can break through the column, US regulations (10 CFR 35.204) cap the breakthrough at 0.02 microcurie of 82Sr and 0.2 microcurie of 85Sr per millicurie of 82Rb eluted, and generators require daily quality control.\n\nUnlike an on-site cyclotron tracer, 82Rb needs no local radiochemistry infrastructure at all beyond the generator and infusion pump, which is why it has spread to community cardiac PET programmes that could never support 13N-ammonia or 15O-water.","status":"approved","asOf":"2026-09-22","links":[{"label":"FDA label: CardioGen-82 (rubidium Rb 82 generator)","url":"https://www.bracco.com/us-en-2020-11-24-spc-cardiogen-82"},{"label":"FDA: CardioGen-82 information","url":"https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/cardiogen-82-information"},{"label":"PMC: rubidium-82 generator yield and efficiency for PET perfusion imaging","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC7599151/"}],"tags":["positron emitter","generator","cardiac perfusion","ultra-short-lived"],"related":[],"indications":[],"sections":[],"technologies":["pet","radionuclide-generators-kits"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"82Rb","element":"Rubidium","massNumber":82,"halfLife":"76 seconds","emissions":["β+ ~95% (max 3.35 MeV)","annihilation γ 511 keV"],"emissionClass":"positron","use":"imaging","production":"Sr-82/Rb-82 generator: 82Sr (half-life ~25 days, itself accelerator-produced) is loaded on a column and 82Rb is eluted with saline on demand.","supply":"adequate","supplyNote":"Generator-based; supply depends on accelerator production of the 82Sr parent, which is made at a small number of specialised facilities, but the roughly 25-day parent half-life lets a single generator serve a clinic for about four weeks between changes.","chelators":[],"pairedWith":[],"since":1989},{"id":"sm-153","kind":"isotope","name":"Samarium-153","aka":["153Sm","Sm-153"],"tldr":"A radioactive metal, given as an injection, that homes in on the actively growing edges of bone and gives off radiation there. It is used to ease pain from cancer that has spread to bone.","summary":"Samarium-153 lexidronam (Quadramet, 153Sm-EDTMP) delivers 153Sm chelated to a bone-seeking phosphonate that concentrates roughly five-fold more in osteoblastic lesions than in normal bone. It decays with a physical half-life of 46.3 hours (1.93 days) by emission of three principal beta-particle energies (maxima around 640, 710 and 810 keV; mean beta energy about 233 keV) plus a 103 keV gamma photon (about 28-29% abundance) that permits scintigraphic imaging of biodistribution.\n\nThe beta particles have an average range in soft tissue of roughly 0.5-0.8 mm and a maximum of about 3 mm (about 1.7 mm in bone), similar in scale to other bone-palliation radiopharmaceuticals but with a much shorter half-life than strontium-89, giving faster onset and clearance.\n\n153Sm is produced in high yield and purity by neutron irradiation of isotopically enriched samarium-152 oxide (152Sm2O3) in a reactor, 152Sm(n,γ)153Sm; this is a routine, widely available reactor product and not considered supply-constrained, though Quadramet's US manufacturer has changed hands and availability has fluctuated commercially.","status":"approved","asOf":"2026-09-22","links":[{"label":"FDA/manufacturer label: Quadramet (samarium Sm-153 lexidronam) prescribing information","url":"https://www.drugs.com/pro/quadramet.html"},{"label":"EMA: Quadramet EPAR product information","url":"https://www.ema.europa.eu/en/documents/product-information/quadramet-epar-product-information_en.pdf"},{"label":"FDA: comparative physical properties of bone-palliation radiopharmaceuticals (Xofigo NDA review)","url":"https://www.accessdata.fda.gov/drugsatfda_docs/nda/2013/203971Orig1s000RiskR.pdf"}],"tags":["therapy","beta emitter","gamma emitter","bone-seeking"],"related":["samarium-153-lexidronam","bone-metastases","sr-89","prostate"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"153Sm","element":"Samarium","massNumber":153,"halfLife":"46.3 hours (1.93 days)","emissions":["β− maxima 640 keV (30%), 710 keV (50%), 810 keV (20%); mean 233 keV","γ 103 keV (~28-29%)"],"emissionClass":"beta-minus","use":"therapy","tissueRange":"Average about 0.5-0.83 mm, maximum about 3 mm in soft tissue","production":"Reactor: neutron irradiation of isotopically enriched samarium-152 oxide, 152Sm(n,γ)153Sm.","supply":"adequate","supplyNote":"Produced routinely by reactor neutron activation of enriched 152Sm; a well-established, non-scarce reactor product, though commercial (Quadramet) availability has seen intermittent supply interruptions unrelated to isotope production capacity.","chelators":["EDTMP"],"pairedWith":["tc-99m"],"since":1997},{"id":"sc-44","kind":"isotope","name":"Scandium-44","aka":["44Sc"],"tldr":"An experimental radioactive metal, lasting about four hours, being developed as a PET-imageable stand-in for lutetium-177 or other therapy metals so a treatment dose can be planned in advance.","summary":"Scandium-44 decays with a 3.97-hour half-life and an unusually high positron branching ratio of about 94%, giving PET image quality that compares favourably with gallium-68 while lasting roughly three times as long, long enough for regional distribution from a centralised production site rather than only local cyclotron use. Its chemistry closely resembles that of lutetium-177 and other trivalent lanthanide-like therapy metals, so DOTA-chelated scandium-44 tracers have been explored as a pre-therapy dosimetry match for 177Lu-labelled radioligands such as PSMA-617, an alternative to using 68Ga for the diagnostic scan when a metal-matched surrogate is preferred.\n\nIt is produced on a medical cyclotron via 44Ca(p,n)44Sc on an enriched calcium-44 target (natural abundance only about 2%, so enrichment adds cost), or via a 44Ti/44Sc generator in which the long-lived (60.4-year) parent titanium-44 supplies scandium-44 on an ongoing basis without a cyclotron, analogous to a 68Ge/68Ga generator.\n\nScandium-44 is also discussed as the diagnostic half of a prospective 44Sc/47Sc theranostic pair, since 44Sc and the beta-emitting therapy isotope scandium-47 are chemically identical, but as of the mid-2020s this pairing remains in early clinical and preclinical research rather than routine practice, and 47Sc production has not yet reached clinical scale.","status":"preclinical","asOf":"2026-09-22","links":[{"label":"PMC: production of scandium radionuclides for theranostic applications","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC8149571/"},{"label":"PMC: current state of 44Ti/44Sc radionuclide generator systems","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC10375575/"}],"tags":["positron emitter","generator","experimental theranostic pair"],"related":[],"indications":[],"sections":[],"technologies":["pet","cyclotron-isotope-production","radioligand-dosimetry"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"44Sc","element":"Scandium","massNumber":44,"halfLife":"3.97 hours","emissions":["β+ 94.3% (mean 632 keV)","γ 1157 keV (99.9%)"],"emissionClass":"positron","use":"imaging","production":"Cyclotron: 44Ca(p,n)44Sc on enriched calcium-44 target; alternatively a 44Ti/44Sc generator (44Ti half-life ~60 years).","supply":"research-only","supplyNote":"Produced at a small number of research cyclotron and generator sites; enriched calcium-44 targets and 44Ti generator stock are both limited, and no scandium radiopharmaceutical has reached routine clinical supply as of the mid-2020s.","chelators":["DOTA"],"pairedWith":[],"since":2013},{"id":"sc-47","kind":"isotope","name":"Scandium-47","aka":["47Sc","Sc-47"],"tldr":"A radioactive metal being developed to pair with imaging twins made of the same element, scandium-43 or scandium-44. Because it is the same chemical element used for both the scan and the treatment, the tracer should behave identically in both roles.","summary":"Scandium-47 decays by beta-minus emission with a half-life of about 3.35 days to stable titanium-47, releasing beta particles with a mean energy around 162 keV (maxima cited between about 440-600 keV depending on the source) and an imageable 159 keV gamma (about 68% abundance), giving a mean tissue range broadly comparable to lutetium-177.\n\nIts intended theranostic partners are the positron emitters scandium-43 (half-life 3.89 hours) and scandium-44 (half-life about 4.04 hours), which would let the same chelator-conjugated ligand be imaged by PET and then dosed with 47Sc using identical chemistry -- an isotopic match analogous to the 64Cu/67Cu copper pair, though scandium's shorter-lived PET isotopes make routine same-day imaging-then-therapy workflows more logistically demanding.\n\n47Sc can be produced in a reactor either directly by fast-neutron irradiation of enriched titanium-47, 47Ti(n,p)47Sc, or indirectly via thermal-neutron capture on enriched calcium-46 to form calcium-47 (half-life 4.54 days), which beta-decays to 47Sc and can also serve as a 47Ca/47Sc generator; it can also be made in a cyclotron by proton irradiation of titanium-48, 48Ti(p,2n)47Sc, though this route has shown lower radionuclidic purity due to co-produced scandium-46 and -48. Production remains at research-reactor and pilot scale (for example, the PRISMAP network's ILL, SCK CEN and NCBJ reactors), and 47Sc-labelled radiopharmaceuticals are in early preclinical and clinical development, not yet FDA- or EMA-approved.","status":"preclinical","asOf":"2026-09-22","links":[{"label":"Production of scandium radionuclides for theranostic applications (EJNMMI Radiopharm Chem, 2021)","url":"https://link.springer.com/article/10.1186/s41181-021-00131-2"},{"label":"47Sc as useful beta-minus-emitter for the radiotheragnostic paradigm (PMC, 2017)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC5824697/"},{"label":"Production and purification of 43Sc and 47Sc from enriched titanium targets (Sci Rep, 2023)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC10730517/"},{"label":"PRISMAP: 47Sc radionuclide portfolio page","url":"https://www.prismap.eu/radionuclides/portfolio/47Sc/"}],"tags":["therapy","beta emitter","gamma emitter","research-only","theranostic pair"],"related":["lu-177","prrt"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"47Sc","element":"Scandium","massNumber":47,"halfLife":"3.35 days","emissions":["β− mean 162 keV","γ 159 keV (~68%)"],"emissionClass":"beta-minus","use":"therapy","tissueRange":"Comparable to 177Lu (sub-millimetre to low-millimetre beta range)","production":"Reactor: thermal-neutron capture on enriched calcium-46, 46Ca(n,γ)47Ca (t1/2 4.54 d) → β− → 47Sc; or fast-neutron irradiation of enriched titanium-47, 47Ti(n,p)47Sc. Also cyclotron 48Ti(p,2n)47Sc.","supply":"research-only","supplyNote":"Produced at research-reactor, gigabecquerel/pilot scale (e.g. PRISMAP network reactors ILL, SCK CEN, NCBJ); not yet available at routine clinical-supply scale.","chelators":["DOTA","DOTATOC/DOTATATE-type macrocycles"],"pairedWith":["ga-68"]},{"id":"sr-89","kind":"isotope","name":"Strontium-89","aka":["89Sr","Sr-89"],"tldr":"A radioactive metal that behaves like calcium and is taken up by bone, particularly where cancer has spread there. A single injection can ease bone pain for weeks by irradiating those spots from within.","summary":"Strontium-89 chloride (Metastron) is a pure beta emitter, decaying by beta-minus emission with a physical half-life of 50.5 days and a single beta energy of 1.463 MeV (100% abundance), giving a maximum tissue range of roughly 8 mm. Because strontium chemically mimics calcium, it is taken up preferentially into bone at sites of increased osteoblastic activity, such as skeletal metastases, and is retained there far longer than in normal bone -- delivering a prolonged local dose from a single injection, used for palliation of painful bone metastases from prostate and breast cancer.\n\nUnlike samarium-153 or radium-223, 89Sr emits essentially no useful gamma photon, so it cannot be imaged with a gamma camera; patient selection instead typically relies on a separate technetium-99m bone scan.\n\n89Sr is produced by thermal-neutron irradiation of an enriched strontium-88 target, 88Sr(n,γ)89Sr, at the DOE's High Flux Isotope Reactor (Oak Ridge National Laboratory) among other sites, yielding radionuclidic purity above 99.8%. As a long-half-life, well-established reactor product, supply has generally been described by the DOE Isotope Program as steady.","status":"approved","asOf":"2026-09-22","links":[{"label":"FDA label: Metastron (strontium-89 chloride injection)","url":"https://www.accessdata.fda.gov/drugsatfda_docs/label/2013/020134s012lbl.pdf"},{"label":"DOE Isotope Program: Ensuring a steady supply of strontium-89","url":"https://www.isotopes.gov/Ensuring-steady-supply-of-strontium-89"},{"label":"FDA: comparative physical properties of bone-palliation radiopharmaceuticals (Xofigo NDA review)","url":"https://www.accessdata.fda.gov/drugsatfda_docs/nda/2013/203971Orig1s000RiskR.pdf"}],"tags":["therapy","pure beta emitter","bone-seeking"],"related":["bone-metastases","sm-153","ra-223","prostate"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"89Sr","element":"Strontium","massNumber":89,"halfLife":"50.5 days","emissions":["β− 1.463 MeV (100%)"],"emissionClass":"beta-minus","use":"therapy","tissueRange":"Up to about 8 mm","production":"Reactor: thermal-neutron irradiation of enriched strontium-88, 88Sr(n,γ)89Sr.","supply":"adequate","supplyNote":"Produced by neutron capture on enriched 88Sr at high-flux reactors such as ORNL's HFIR; the DOE Isotope Program describes supply as steady, though it is a niche, single-purpose product with few suppliers.","chelators":[],"pairedWith":["tc-99m"],"since":1993},{"id":"tc-99m","kind":"isotope","name":"Technetium-99m","aka":["99mTc","Tc-99m"],"tldr":"The single most widely used medical radioisotope: a metastable metal with a six-hour lifetime, milked on demand from a bedside generator (a 'moly cow') and attached to a cold kit to image bone, heart, kidneys or lymph nodes.","summary":"Technetium-99m decays with a 6.0067-hour half-life, almost entirely by isomeric transition, emitting a 140.5 keV gamma ray that sits close to the energy of diagnostic X-ray equipment and is close to ideal for gamma-camera and SPECT imaging. It underpins on the order of tens of millions of scans a year worldwide (bone scans, myocardial perfusion, sentinel lymph node mapping, renal and hepatobiliary studies), each prepared on site by adding the eluted pertechnetate to a lyophilised cold kit.\n\nIt is the daughter of molybdenum-99 (65.94-hour half-life), which is shipped to hospital and radiopharmacy radiopharmacies worldwide as a 99Mo/99mTc generator; the longer-lived parent decays continuously and the daughter is eluted, typically once or twice a day, for use within hours before it decays away. This generator relationship is what makes just-in-time global distribution of a six-hour isotope possible at all.\n\nBecause supply of 99mTc is entirely downstream of 99Mo production, its reliability tracks the well-documented fragility of that upstream reactor supply chain (see mo-99): unplanned reactor outages, most recently the October 2024 shutdown of the High Flux Reactor in the Netherlands, have repeatedly caused short-notice shortages of Tc-99m-based scans.","status":"established","asOf":"2026-09-22","links":[{"label":"NNDC/LNHB: Tc-99m decay data tables","url":"http://www.lnhb.fr/nuclides/Tc-99m_tables.pdf"},{"label":"OECD/NEA: current trends in the supply and utilisation of medical radioisotopes (2025)","url":"https://www.oecd-nea.org/upload/docs/application/pdf/2025-10/7743_medical_radioisotopes_supply_rev.pdf"}],"tags":["gamma emitter","generator","most widely used"],"related":["technetium-sulfur-colloid","tilmanocept-tc99m","mo-99"],"indications":[],"sections":[],"technologies":["spect","spect-ct","radionuclide-generators-kits","research-reactor-isotope-production","nuclear-medicine-hardware"],"targets":[],"drugs":[],"companies":["curium","ge-healthcare","lantheus","cardinal-health"],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"99mTc","element":"Technetium","massNumber":99,"halfLife":"6.0067 hours","emissions":["γ 140.5 keV (89%)","internal conversion electrons (~11% of decays)"],"emissionClass":"gamma","use":"imaging","production":"Eluted from a 99Mo/99mTc generator (the '99Mo/99mTc generator' or 'moly cow'); 99Mo is made by fission of enriched uranium targets in a research reactor or by neutron activation of enriched molybdenum-98.","supply":"tight","supplyNote":"Supply is set entirely by upstream 99Mo production; ageing research reactors and periodic unplanned outages (for example the HFR shutdown of October 2024) have caused recurrent short-notice Tc-99m shortages despite no direct constraint on technetium itself.","chelators":[],"pairedWith":[],"since":1964},{"id":"tb-161","kind":"isotope","name":"Terbium-161","aka":["161Tb","Tb-161"],"tldr":"A radioactive metal, chemically almost identical to the widely-used lutetium-177, that gives off the same kind of medium-range particles plus a burst of extra very-short-range electrons. Those extra electrons may let it do more damage to a cancer cell than lutetium-177 while using the same delivery molecules.","summary":"Terbium-161 decays by beta-minus emission with a half-life of 6.95 days (very close to lutetium-177's 6.65 days) to stable dysprosium-161, and shares much of 177Lu's chemistry (both are trivalent lanthanides suited to DOTA-type chelators), so it can be substituted directly into existing DOTATATE, DOTATOC and PSMA-617-type ligands.\n\nWhat distinguishes it is a large yield of low-energy conversion and Auger electrons -- roughly 2.3 electrons above 3 keV per decay, with ranges from nanometres to a few tens of nanometres -- alongside its 154 keV mean-energy beta particles, which give it a mean tissue range similar to 177Lu (about 0.7 mm) but potentially more damage to single cells and micrometastases through the additional short-range electrons. It also emits imageable gamma/X-rays around 48.9 keV (17%) and 74.6 keV (10%), suitable for SPECT, including simultaneous dual-isotope imaging alongside 177Lu.\n\nProduction is analogous to no-carrier-added 177Lu: thermal-neutron irradiation of enriched gadolinium-160 targets produces short-lived 161Gd (half-life 3.66 minutes), which beta-decays to 161Tb; the Tb is then chemically separated from the bulk Gd. It therefore depends on the same high-flux research reactors used for 177Lu (a European PRISMAP network of ILL, SCK CEN and NCBJ reactors, plus PSI's SINQ spallation source, and a University of Utah TRIGA/University of Missouri collaboration in the US), and remains available only in gigabecquerel, research-scale monthly batches. Terbium-161-labelled PSMA and somatostatin-receptor agents are in early clinical investigation and are not approved by the FDA or EMA.","status":"phase-1","asOf":"2026-09-22","links":[{"label":"Opportunities and potential challenges of using terbium-161 (Eur J Nucl Med Mol Imaging, 2023)","url":"https://link.springer.com/article/10.1007/s00259-023-06316-y"},{"label":"Potentials and practical challenges of terbium-161 labeled radiopharmaceuticals (PMC, 2025)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC12494511/"},{"label":"DOE/isotopes.gov: To Advance Cancer Therapy, University Starts Producing Tb-161","url":"https://www.isotopes.gov/node/1517"},{"label":"PRISMAP: 161Tb radionuclide portfolio page","url":"https://www.prismap.eu/radionuclides/portfolio/161Tb/"}],"tags":["therapy","beta emitter","auger electron emitter","research-only"],"related":["lu-177","prrt","idea-reg-alpha-emitter-portfolio","auger-electron-therapy"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"161Tb","element":"Terbium","massNumber":161,"halfLife":"6.95 days","emissions":["β− mean 154 keV (to stable 161Dy)","conversion + Auger electrons (~2.27 per decay, >3 keV)","γ/X-ray 48.9 keV (17%)","γ/X-ray 74.6 keV (10.2%)"],"emissionClass":"mixed","use":"therapy","tissueRange":"Mean about 0.7 mm (beta), plus nanometre-to-tens-of-nanometre range from Auger/conversion electrons","production":"Reactor: thermal-neutron irradiation of enriched gadolinium-160, 160Gd(n,γ)161Gd, which beta-decays (t1/2 3.66 min) to 161Tb; chemically separated from the Gd target.","supply":"research-only","supplyNote":"Produced at gigabecquerel, monthly-batch scale by the European PRISMAP network (ILL, SCK CEN, NCBJ reactors; PSI's SINQ) and by a University of Utah/University of Missouri TRIGA-reactor collaboration; not yet available at Lu-177-scale clinical supply.","chelators":["DOTA","DOTATATE/DOTATOC-type macrocycles"],"pairedWith":["ga-68"]},{"id":"tl-201","kind":"isotope","name":"Thallium-201","aka":["201Tl"],"tldr":"A radioactive potassium look-alike with a three-day lifetime, injected to see how well blood reaches, and heart muscle survives in, different parts of the heart on a SPECT scan.","summary":"Thallium-201 decays by electron capture to stable mercury-201 with a 73-hour (about 3-day) physical half-life, and is handled biologically as a potassium analogue, taken up by viable myocardium in proportion to regional blood flow and cell membrane integrity. Imaging exploits the mercury X-rays emitted at 69-83 keV (about 88 per 100 decays) rather than its weaker 135 and 167 keV gamma rays, using a low-energy collimator.\n\nIt is produced on a cyclotron by proton bombardment of enriched thallium-203, via 203Tl(p,3n)201Pb, and the resulting lead-201 (half-life about 9.4 hours) is left to decay for roughly a day before a second chemical separation yields carrier-free thallium-201.\n\nBecause its relatively long physical and biological half-lives allow flexible same-day or next-day rest/redistribution imaging without a dedicated on-site cyclotron, thallium-201 was the dominant myocardial perfusion SPECT agent for decades; it has since been substantially displaced by technetium-99m-based perfusion agents (which give a lower radiation dose and better image quality) but remains in use, particularly for myocardial viability assessment, where thallium's redistribution behaviour is diagnostically useful.","status":"established","asOf":"2026-09-22","links":[{"label":"Radiopaedia: thallium-201 scintigraphy","url":"https://radiopaedia.org/articles/thallium-201-scintigraphy"},{"label":"Health Canada product monograph: Thallous Chloride Tl 201 Injection","url":"https://pdf.hres.ca/dpd_pm/00050840.PDF"}],"tags":["gamma emitter","cardiac perfusion","myocardial viability"],"related":[],"indications":[],"sections":[],"technologies":["spect","cyclotron-isotope-production"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"201Tl","element":"Thallium","massNumber":201,"halfLife":"73 hours (3.04 days)","emissions":["Hg X-rays 69-83 keV (~88%)","γ 135 keV (~3%)","γ 167 keV (~10%)"],"emissionClass":"gamma","use":"imaging","production":"Cyclotron: 203Tl(p,3n)201Pb on enriched thallium-203, followed by decay of 201Pb (half-life ~9.4 hours) to 201Tl and a second chemical separation.","supply":"adequate","supplyNote":"Cyclotron-produced at a limited number of high-energy facilities; clinical demand has declined relative to Tc-99m myocardial perfusion agents but remains in routine use for viability studies.","chelators":[],"pairedWith":[],"since":1975},{"id":"th-227","kind":"isotope","name":"Thorium-227","aka":["227Th","Th-227"],"tldr":"A radioactive metal that, once it decays, keeps generating more damaging radioactive particles inside the tumour for weeks. Because it lasts longer than most similar treatments, it can be attached to slow-moving carriers such as full-sized antibodies.","summary":"Thorium-227 is an alpha emitter with an 18.7-day half-life -- long enough, unlike most alpha emitters, to be conjugated to slow-clearing targeting molecules such as full antibodies rather than only fast peptides. It decays through a five-alpha cascade (via 223Ra, 219Rn, 215Po, 211Pb, 211Bi, 211Po) to stable 207Tl/207Pb, releasing a total of about 32.4 MeV of alpha energy and roughly 0.96 MeV of beta energy per decay chain, making it an in vivo generator of its own daughter, radium-223.\n\nIt is chelated using octadentate 3,2-hydroxypyridinone (3,2-HOPO) ligands rather than the DOTA-family macrocycles used for most other alpha and beta emitters, and has been developed by Bayer as 'targeted thorium conjugates' (TTCs), including antibody-based constructs such as BAY 2315497 (anti-PSMA) and BAY2701439 (anti-HER2), both tested in early-phase trials.\n\n227Th is obtained from the same generator/supply chain as radium-223: it is the immediate alpha-decay daughter of actinium-227 (itself made by neutron irradiation of radium-226 in a reactor, 226Ra(n,γ)227Ra → β− → 227Ac), separated from the growing 227Ac/227Th/223Ra generator column. Because production piggybacks on the well-established 223Ra supply chain (ORNL, PNNL, Rosatom, Bayer), 227Th is considered available at the research and early-clinical scale, though its co-produced daughter 223Ra must be removed and accounted for as a radioactive impurity in any 227Th-labelled drug product.","status":"phase-1","asOf":"2026-09-22","links":[{"label":"Targeted thorium-227 conjugates as treatment options in oncology (Front Med, 2023)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC9885765/"},{"label":"Production and supply of alpha particle emitting radionuclides for TAT (JNM, 2021)","url":"https://jnm.snmjournals.org/content/jnumed/early/2021/07/22/jnumed.120.261016.full.pdf"},{"label":"Development of radiopharmaceuticals for targeted alpha therapy (PMC, 2022)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC9812962/"}],"tags":["therapy","alpha emitter","antibody-compatible","in vivo generator"],"related":["ra-223","targeted-alpha-therapy","her2","psma"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"227Th","element":"Thorium","massNumber":227,"halfLife":"18.7 days","emissions":["α cascade (via 223Ra, 219Rn, 215Po, 211Pb, 211Bi, 211Po) to stable 207Pb: total ~32.4 MeV α, ~0.96 MeV β per chain","γ 236 keV (11.2%) and 50 keV (8.5%)"],"emissionClass":"alpha","use":"therapy","tissueRange":"Tens of micrometres (alpha range), delivered progressively as the daughter chain decays","production":"Generator: harvested from a reactor-derived 227Ac source (226Ra(n,γ)227Ra → β− → 227Ac), from which 227Th is separated on an ongoing basis.","supply":"emerging","supplyNote":"Piggybacks on the 223Ra/227Ac supply chain (ORNL, PNNL, Rosatom, Bayer, and in Europe the Institute for Energy Technology in Norway distributed via Bayer, or JRC Karlsruhe for the PRISMAP consortium); available at research and early-clinical scale but not yet at large commercial scale.","chelators":["3,2-HOPO (octadentate hydroxypyridinone)"],"pairedWith":["zr-89"]},{"id":"y-86","kind":"isotope","name":"Yttrium-86","aka":["86Y"],"tldr":"A PET-visible radioactive stand-in for the treatment isotope yttrium-90, used to see in advance, on a scan, exactly where a yttrium-90 therapy dose would go and how much radiation each organ would receive.","summary":"Yttrium-90, used for radioembolisation (TARE/SIRT) and older radioimmunotherapy agents, is a pure beta emitter with no directly imageable gamma or positron emission, which makes patient-specific pre-therapy dosimetry difficult. Yttrium-86 solves that problem: it is chemically identical to yttrium-90, so an 86Y-labelled version of the same antibody, peptide or microsphere construct has an identical biodistribution, and its 14.7-hour half-life with about 33% positron emission allows PET imaging over two to three days, long enough to build a full time-activity curve and calculate the organ and tumour doses a subsequent 90Y therapy would deliver.\n\nIt is produced on a cyclotron via 86Sr(p,n)86Y on an enriched strontium-86 target (typically SrCO3 or SrO), the preferred route because it gives the highest radionuclidic purity; the main radionuclidic impurity, 87mY, is normally kept below a few percent when highly enriched target material is used. Bombardments of a few hours at modest beam currents (2-6 microamps) are typical.\n\nThe approach was first used clinically at Forschungszentrum Jülich for pre-therapy dosimetry ahead of 90Y-citrate treatment of bone metastases, and has since been applied to 86Y-DOTA-peptide imaging ahead of 90Y-labelled somatostatin analogue therapy; it remains a research and specialist-dosimetry tool rather than a routinely stocked clinical isotope, since both the cyclotron target and the imaging protocol are non-standard.","status":"preclinical","asOf":"2026-09-22","links":[{"label":"PMC: 86Y-based PET radiopharmaceuticals, radiochemistry and applications","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC3184346/"},{"label":"DOE Isotope Program (NIDC): yttrium-86 availability","url":"https://www.isotopes.gov/node/215"}],"tags":["positron emitter","dosimetry surrogate","theranostic pair"],"related":[],"indications":[],"sections":[],"technologies":["pet","radioligand-dosimetry","cyclotron-isotope-production"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"86Y","element":"Yttrium","massNumber":86,"halfLife":"14.7 hours","emissions":["β+ ~33% (max 3.15 MeV)","electron capture ~67%","multiple γ (443-1921 keV)"],"emissionClass":"positron","use":"imaging","production":"Cyclotron: 86Sr(p,n)86Y on enriched strontium-86 target (SrCO3 or SrO), typically 2-6 microamp beam current for under 4 hours.","supply":"research-only","supplyNote":"Made at a small number of research cyclotrons (including the US DOE Isotope Program's Brookhaven Linac Isotope Producer, available on an as-needed basis) with enriched 86Sr targets; used for dosimetry research rather than stocked as a routine clinical isotope.","chelators":["DOTA"],"pairedWith":["y-90"],"since":1993},{"id":"y-90","kind":"isotope","name":"Yttrium-90","aka":["90Y","Y-90"],"tldr":"A radioactive metal that fires high-energy particles a short distance into surrounding tissue. Millions of microscopic beads carrying it are injected into the artery feeding a liver tumour, where they lodge and irradiate the tumour from inside.","summary":"Yttrium-90 is a near-pure beta emitter (a small pair-production fraction allows PET imaging of its distribution) that decays to stable zirconium-90 with a physical half-life of 64.1 hours (2.67 days). Its beta particles have a mean energy near 0.93-0.94 MeV, a mean tissue range of about 2.5 mm and a maximum of roughly 11 mm, and 94% of the total dose is delivered within about 11 days.\n\nIt is the workhorse isotope of liver radioembolisation (TARE/SIRT): glass microspheres (TheraSphere) with 90Y built into the glass matrix, and resin microspheres (SIR-Spheres) with 90Y bound to the surface, are delivered via a hepatic-artery catheter and become permanently embedded in and around the tumour. It is also used, chelated to peptides and antibodies, for radioligand and radioimmunotherapy (e.g. ibritumomab tiuxetan).\n\n90Y for microsphere manufacture is produced either by decay of its 28.8-year fission-product parent strontium-90 (chemically separated as it decays) or by direct reactor neutron activation of stable yttrium-89. Because the parent Sr-90/generator route and direct reactor activation are both well established at multiple sites, supply for the approved microsphere products is generally adequate.","status":"approved","asOf":"2026-09-22","links":[{"label":"FDA PMA summary: TheraSphere Yttrium-90 Glass Microspheres","url":"https://www.accessdata.fda.gov/cdrh_docs/pdf20/P200029C.pdf"},{"label":"The development, commercialization, and clinical context of yttrium-90 (PMC, 2016)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC5514171/"},{"label":"Yttrium-90 Radioembolization Dosimetry: What Trainees Need to Know (PMC, 2020)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC7732571/"}],"tags":["therapy","beta emitter","radioembolisation"],"related":["radioembolisation-tare","tare","hcc","hcc-intermediate","ibritumomab-tiuxetan","sirtex","boston-scientific"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"90Y","element":"Yttrium","massNumber":90,"halfLife":"64.1 hours (2.67 days)","emissions":["β− average 0.93-0.94 MeV, maximum 2.28 MeV"],"emissionClass":"beta-minus","use":"therapy","tissueRange":"Mean about 2.5 mm, maximum about 11 mm","production":"Decay of fission-product parent 90Sr (chemically separated on decay), or direct reactor neutron activation of stable 89Y, 89Y(n,γ)90Y.","supply":"adequate","supplyNote":"Available from established 90Sr/90Y separation and direct reactor-activation routes at multiple sites supplying the two FDA-approved microsphere products.","chelators":["DOTA"],"pairedWith":["tc-99m"]},{"id":"zr-89","kind":"isotope","name":"Zirconium-89","aka":["89Zr"],"tldr":"A radioactive metal that lasts about three days, long enough to attach to a whole antibody and follow it around the body for several days on a PET scan, which is why it underpins 'immuno-PET'.","summary":"Zirconium-89 decays with a 78.4-hour (3.3-day) half-life, mostly by electron capture (about 77%) and partly by positron emission (about 23%), to metastable yttrium-89, which promptly emits a 909 keV gamma. That three-day half-life is the reason 89Zr is the default radiometal for immuno-PET: intact monoclonal antibodies take two to four days to reach optimal tumour-to-background ratios in vivo, far longer than any conventional PET isotope survives, but well matched to zirconium-89's decay.\n\nIt is made almost entirely by cyclotron bombardment of a solid yttrium-89 target, 89Y(p,n)89Zr; because yttrium-89 is 100% naturally abundant the target needs no isotopic enrichment, which keeps production comparatively simple and inexpensive, though proton energy has to be kept below about 13 MeV to avoid the long-lived 88Zr impurity. After irradiation, 89Zr is purified on a hydroxamate resin and conjugated to antibodies through chelators such as desferrioxamine (DFO) or newer macrocyclic cages designed to resist the free-zirconium bone uptake that DFO-based constructs can show over several days.\n\nIn the Nuclide graph, 89Zr's main current oncology use is CAIX PET with 89Zr-girentuximab in renal cell carcinoma, which forms an emerging diagnostic-therapeutic pair with 177Lu- or 225Ac-labelled girentuximab.","status":"emerging","asOf":"2026-09-22","links":[{"label":"Springer: clinical nuclear medicine applications of zirconium-89 immuno-PET","url":"https://link.springer.com/article/10.1186/s41181-025-00418-8"},{"label":"EJNMMI Radiopharmacy & Chemistry: good practices for 89Zr production","url":"https://ejnmmipharmchem.springeropen.com/articles/10.1186/s41181-024-00258-y"}],"tags":["positron emitter","immuno-PET","long-lived PET"],"related":["girentuximab-zr89"],"indications":["rcc"],"sections":[],"technologies":["immuno-pet","caix-pet","cyclotron-isotope-production","pet"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"89Zr","element":"Zirconium","massNumber":89,"halfLife":"78.4 hours (3.3 days)","emissions":["electron capture ~77%","β+ ~23% (mean 396 keV)","γ 909 keV (from 89mY, 99%)"],"emissionClass":"positron","use":"imaging","production":"Cyclotron: 89Y(p,n)89Zr on a solid yttrium-89 target (proton energy kept below ~13 MeV to avoid 88Zr impurity); 89Y(d,2n)89Zr with deuterons is an alternative.","supply":"adequate","supplyNote":"Yttrium-89 is 100% naturally abundant and needs no enrichment, and purification chemistry is well established, so 89Zr is considered one of the more scalable non-conventional PET radiometals; several commercial suppliers now provide it.","chelators":["DFO (desferrioxamine)","DFO*","macropa/other next-generation cages"],"pairedWith":["lu-177","ac-225"],"since":2010}]