Isotope Directory
A curated directory of the isotopes that matter most for medicine, energy, quantum technologies, advanced materials, and strategic supply chains.
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Most elements exist in more than one form. These different forms are called isotopes. They have the same number of protons, so they are the same element, but different numbers of neutrons.
Some isotopes are stable. Others are unstable and release energy as they change. That energy and those nuclear properties are what make certain isotopes useful in medicine, energy systems, quantum technologies, and industry.
This directory focuses on the isotopes that currently matter most. For the broader external landscape, use the Links page.
Medical & Theranostics
Mo-99 / Tc-99m
DiagnosticsSupply chain criticalTechnetium-99m is the dominant isotope in diagnostic nuclear medicine. It is produced from molybdenum-99, making this parent-daughter pair one of the most important medical isotope systems in the world.
Main uses: Cardiac imaging, bone scans, oncology imaging, and a wide range of diagnostic nuclear medicine procedures.
Note: Global supply depends on a relatively small number of production routes and facilities.
Yb-176
PrecursorMedicalStableStable ytterbium isotope used as target material for no-carrier-added Lu-177 production. Irradiation of enriched Yb-176 produces Lu-177 without the carrier lutetium burden of older production routes.
Main uses: Critical precursor for n.c.a. Lu-177 used in theranostics. Supply depends on enriched target availability, reactor or accelerator access, and separation capacity, not only on demand for the finished therapeutic isotope.
Lu-177
TheranosticsTherapyLutetium-177 is a central therapeutic isotope in targeted radioligand therapy, where radioactive payloads are delivered selectively to cancer cells.
Main uses: Prostate cancer and neuroendocrine tumor therapies, with broader oncology applications expanding.
Note: Rising clinical demand has made reliable supply a major industry focus.
Ac-225
Alpha therapyEmergingActinium-225 is one of the most important emerging alpha-emitting isotopes for targeted cancer therapy. Alpha particles deposit high energy over a very short distance.
Main uses: Targeted alpha therapy research and development in oncology.
Note: Production is constrained and technically demanding, which currently limits broader clinical scale-up.
F-18
PETDiagnosticsFluorine-18 is the primary PET imaging isotope used in modern diagnostic oncology and related imaging.
Main uses: FDG PET scans and other fluorine-18 based diagnostic agents.
Ga-68
PETDiagnosticsGallium-68 is a generator-produced PET isotope widely used in targeted diagnostic imaging.
Main uses: PET imaging agents for oncology and specialized diagnostic applications.
I-131
TherapyDiagnosticsIodine-131 is one of the most established therapeutic and diagnostic radioisotopes in nuclear medicine.
Main uses: Thyroid therapy and diagnostic procedures, along with selected other nuclear medicine applications.
I-123
DiagnosticsIodine-123 is preferred for many diagnostic iodine imaging applications because of its favorable imaging characteristics.
Main uses: Thyroid imaging and other diagnostic nuclear medicine procedures.
I-124
PETResearchIodine-124 is a longer-lived PET-relevant iodine isotope used mainly in research and selected imaging contexts.
Main uses: PET research and specialized iodine-based imaging studies.
Y-90
TherapyYttrium-90 is a widely used therapeutic radioisotope in targeted cancer treatment.
Main uses: Liver cancer therapies and other targeted radiotherapeutic applications.
Ra-223
Alpha therapyRadium-223 is an alpha-emitting therapeutic isotope used in the treatment of bone metastases.
Main uses: Targeted treatment of bone metastases, particularly in prostate cancer care.
Tb-161
TheranosticsEmergingTerbium-161 is an emerging theranostic isotope with promising therapeutic properties and growing research interest.
Main uses: Experimental and developing radiopharmaceutical therapy applications.
Cu-64
ImagingTherapyCopper-64 is a versatile isotope used in both imaging and therapeutic research.
Main uses: PET imaging research and radiopharmaceutical development.
Cu-67
TherapyEmergingCopper-67 is a therapeutic copper isotope of growing interest for radiopharmaceutical applications.
Main uses: Targeted radiotherapy research and emerging clinical development.
Zr-89
PETZirconium-89 is increasingly used in antibody-based PET imaging because of its longer half-life.
Main uses: Immuno-PET and antibody imaging applications.
In-111
DiagnosticsIndium-111 is an established diagnostic isotope used in specialized nuclear medicine procedures.
Main uses: Infection imaging, labeled white-cell studies, and other diagnostic applications.
Tl-201
DiagnosticsThallium-201 is a historically important cardiac imaging isotope that remains in use in some clinical settings.
Main uses: Myocardial perfusion imaging and related diagnostic procedures.
Sm-153
TherapySamarium-153 is used therapeutically for pain palliation in patients with bone metastases.
Main uses: Bone pain palliation and selected therapeutic nuclear medicine applications.
Re-186 / Re-188
TherapyRhenium-186 and rhenium-188 are therapeutic isotopes used in selected nuclear medicine applications.
Main uses: Targeted therapy and palliative treatment research or specialized clinical use.
At-211
Alpha therapyResearchAstatine-211 is an alpha-emitting isotope of strong research interest for targeted radiotherapy.
Main uses: Experimental targeted alpha therapy.
Pb-212 / Bi-212
Alpha therapyEmergingLead-212 and bismuth-212 are important isotopes in emerging targeted alpha therapy approaches.
Main uses: Alpha therapy development and related radiopharmaceutical research.
Energy & Nuclear
He-3
StrategicQuantumCryogenicsHelium-3 is a rare strategic isotope used in quantum research, ultra-low temperature systems, neutron detection, and specialized applications.
Main uses: Dilution refrigerators, quantum infrastructure, neutron detection, and specialized research.
Note: Limited production pathways make supply a recurring strategic concern.
Li-6
FusionStrategicLithium-6 is important for fusion energy concepts that rely on tritium breeding in reactor blanket systems.
Main uses: Tritium breeding materials, fusion research, and specialized nuclear applications.
Note: Isotopic composition of lithium becomes more important as fusion systems advance.
U-235
FissileEnergyUranium-235 is the primary fissile isotope used in most commercial nuclear reactors.
Main uses: Nuclear fuel for commercial and research reactors.
U-238
FertileEnergyUranium-238 is the dominant isotope in natural uranium and a fertile material in nuclear fuel cycles.
Main uses: Nuclear fuel matrices, breeding contexts, and broader nuclear fuel-cycle applications.
U-233
FissileThorium cycleUranium-233 is a fissile isotope relevant to thorium-based fuel cycle concepts.
Main uses: Thorium fuel cycle research and advanced reactor concepts.
Pu-239
FissileEnergyPlutonium-239 is a key fissile isotope produced in reactors and used in certain fuel-cycle strategies.
Main uses: Nuclear fuel cycles and specialized nuclear applications.
Pu-238
SpacePowerPlutonium-238 is a critical isotope for long-lived space power systems.
Main uses: Radioisotope thermoelectric generators for space missions and specialized power applications.
Th-232
FertileEnergyThorium-232 is the fertile isotope at the center of thorium fuel cycle research.
Main uses: Advanced nuclear fuel cycle research and thorium-based reactor concepts.
H-3 (Tritium)
FusionEnergyTritium is a radioactive hydrogen isotope important to certain fusion approaches and specialized nuclear applications.
Main uses: Fusion research, specialized nuclear systems, and selected industrial or research uses.
H-2 (Deuterium)
FusionResearchDeuterium is the stable heavy isotope of hydrogen and a foundational material in fusion research.
Main uses: Fusion experiments, research applications, and specialized chemical or industrial uses.
Li-7
NuclearCoolant systemsLithium-7 is important in some nuclear system chemistries and related industrial contexts.
Main uses: Nuclear coolant chemistry and specialized lithium applications.
He-4
CryogenicsIndustrialHelium-4 is the common isotope of helium and a foundational material for cryogenics and many industrial processes.
Main uses: Cryogenics, cooling systems, leak detection, and broad industrial applications.
Quantum & Advanced Materials
Si-28
QuantumSemiconductorsSilicon-28 is one of the most important stable isotopes for quantum computing and advanced semiconductor research because highly enriched Si-28 reduces nuclear spin noise.
Main uses: Silicon-based quantum devices, spin qubits, and high-purity semiconductor research.
Note: Supply of high-purity Si-28 is increasingly strategic as quantum hardware develops.
B-11
QuantumMaterialsBoron-11 is the preferred boron isotope for many quantum and advanced materials applications because of its nuclear properties.
Main uses: Advanced materials, quantum-related research, and specialized industrial applications.
Note: B-10 is preferred instead where high neutron absorption is required.
Ge-70
QuantumSemiconductorsGermanium-70 is a spin-free germanium isotope of growing interest for quantum devices and advanced semiconductor research.
Main uses: Quantum device research, silicon-germanium systems, and advanced semiconductor materials.
Note: Isotopically controlled germanium is becoming more relevant as quantum hardware explores hybrid material systems.
B-10
NuclearControl materialsBoron-10 has a high neutron absorption cross section, making it valuable in nuclear control and shielding contexts.
Main uses: Control materials, neutron absorbers, and specialized nuclear applications.
C-12
QuantumMaterialsHighly purified carbon-12 is relevant to certain quantum and precision materials applications where isotopic uniformity matters.
Main uses: Precision materials research and selected quantum-related applications.
C-13
QuantumResearchCarbon-13 is important in quantum sensing, NMR, and advanced materials research.
Main uses: NMR, tracing, quantum sensing, and specialized research applications.
Si-29
QuantumSilicon-29 is a spin-bearing silicon isotope and is often the isotope being reduced when producing high-purity Si-28 environments.
Main uses: Relevant mainly as the isotope depleted in quantum-grade silicon enrichment.
O-18
MedicalResearchOxygen-18 is important in the production pathway for fluorine-18 and in specialized research applications.
Main uses: F-18 production pathways and research tracing applications.
N-15
ResearchMaterialsNitrogen-15 is a stable isotope used in research and specialized tracing applications.
Main uses: Research tracing, environmental studies, and specialized materials work.
Cl-37
Advanced reactorsMaterialsChlorine-37 is relevant in some advanced reactor chemistry and materials discussions.
Main uses: Advanced reactor research and specialized materials contexts.
Industrial & Research Staples
C-14
ResearchTracingCarbon-14 is essential for radiocarbon dating, tracing, and a wide range of scientific applications.
Main uses: Dating, biological tracing, environmental research, and laboratory applications.
Co-60
IndustrialMedicalPower reactorCobalt-60 is produced by irradiating cobalt-59 in a reactor until it becomes cobalt-60. Unlike short-lived medical isotopes, it has a half-life of about 5.3 years, long enough to process into sealed sources and ship globally. A large share of global supply comes from CANDU power reactors in Ontario, with processing concentrated through specialized source manufacturers such as Nordion. Other production exists in Russia, China, India, and Argentina. This is a power-reactor isotope pathway, not a research-reactor pathway.
Main uses: Sterilization of single-use medical devices, industrial irradiation, and selected cancer therapy systems. Supply depends on power-reactor access, harvest logistics, and source fabrication rather than research-reactor networks.
Ir-192
IndustrialIridium-192 is a major industrial radiography isotope used to inspect welds and structural materials.
Main uses: Non-destructive testing and industrial inspection.
Se-75
IndustrialSelenium-75 is used in industrial radiography and specialized measurement applications.
Main uses: Industrial inspection and selected measurement systems.
Am-241
IndustrialInstrumentationAmericium-241 is widely used in industrial gauges and certain consumer and instrumentation applications.
Main uses: Smoke detectors, industrial gauging, and specialized instrumentation.
Cf-252
ResearchNeutron sourceCalifornium-252 is a powerful neutron source used in research, industry, and specialized nuclear applications.
Main uses: Neutron radiography, reactor startup sources, and specialized analysis.
Cs-137
IndustrialCalibrationCesium-137 is used in industrial gauges, calibration, and specialized radiation applications.
Main uses: Industrial measurement, calibration sources, and selected research uses.
Sr-90
IndustrialPower sourcesStrontium-90 is used in specialized power sources and industrial applications.
Main uses: Radioisotope power sources and specialized industrial systems.
Kr-85
IndustrialKrypton-85 is used in specialized industrial measurement and related applications.
Main uses: Industrial gauging and specialized technical systems.
Ni-63
IndustrialInstrumentationNickel-63 is used in electron-capture detectors and specialized instrumentation.
Main uses: Gas chromatography detectors and selected instrumentation applications.
Fe-55
IndustrialResearchIron-55 is used in specialized measurement and research applications.
Main uses: X-ray fluorescence related uses and specialized research systems.
Wider Isotope World
For official databases, institutions, public companies, and private companies across the broader isotope landscape, visit the Links page.
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