# Technetium-99m

Source: https://nuclide.cc/isotopes/tc-99m/  
Nuclide record `tc-99m` (Isotope). Data CC BY-NC 4.0, attribute "Data from Nuclide (nuclide.cc)"; commercial use needs a licence.

## TL;DR

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.

It 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.

Because 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.

## Fields

- Kind: Isotope
- Status: established
- Last checked: 2026-09-22
- Also known as: 99mTc; Tc-99m
- Tags: gamma emitter; generator; most widely used

## Sources

- NNDC/LNHB: Tc-99m decay data tables: http://www.lnhb.fr/nuclides/Tc-99m_tables.pdf
- OECD/NEA: current trends in the supply and utilisation of medical radioisotopes (2025): https://www.oecd-nea.org/upload/docs/application/pdf/2025-10/7743_medical_radioisotopes_supply_rev.pdf

## Connected records

- drugs: [Rubidium Rb-82 chloride](https://nuclide.cc/drugs/rb-82-chloride/), [Sodium fluoride F-18](https://nuclide.cc/drugs/f-18-naf/), [Technegas (technetium Tc-99m labelled carbon inhalation aerosol)](https://nuclide.cc/drugs/technegas/), [Technetium (99mTc) pexiretide](https://nuclide.cc/drugs/pexiretide-tc99m/), [Technetium Tc-99m albumin aggregated (MAA)](https://nuclide.cc/drugs/tc-99m-maa/), [Technetium Tc-99m medronate (MDP)](https://nuclide.cc/drugs/tc-99m-mdp/), [Technetium Tc-99m PSMA agents (PSMA-I&S)](https://nuclide.cc/drugs/tc-99m-psma-imaging/), [Technetium Tc-99m pyrophosphate](https://nuclide.cc/drugs/tc-99m-pyrophosphate/), [Technetium Tc-99m sestamibi](https://nuclide.cc/drugs/tc-99m-sestamibi/), [Technetium Tc-99m sulfur colloid](https://nuclide.cc/drugs/technetium-sulfur-colloid/), [Technetium Tc-99m tetrofosmin](https://nuclide.cc/drugs/tc-99m-tetrofosmin/), [Technetium-99m exametazime (brain perfusion)](https://nuclide.cc/drugs/tc-99m-hmpao-brain/), [Technetium-99m tilmanocept](https://nuclide.cc/drugs/tilmanocept-tc99m/), [Thallous chloride Tl-201](https://nuclide.cc/drugs/tl-201-chloride/), [Yttrium-90 resin microspheres](https://nuclide.cc/drugs/y-90-resin-microspheres/)
- isotopes: [Krypton-81m](https://nuclide.cc/isotopes/kr-81m/), [Molybdenum-99](https://nuclide.cc/isotopes/mo-99/)
- technologies: [Cold kit formulation](https://nuclide.cc/technologies/cold-kit-formulation/), [Gamma probes, handheld gamma cameras and dose calibrators](https://nuclide.cc/technologies/gamma-probes-dose-calibrators/), [Hot cells and radiation shielding](https://nuclide.cc/technologies/hot-cells-and-shielding/), [Molybdenum-99/technetium-99m generators](https://nuclide.cc/technologies/mo99-tc99m-generators/), [Nuclear medicine and total-body PET hardware](https://nuclide.cc/technologies/nuclear-medicine-hardware/), [Radionuclide generators and cold kits](https://nuclide.cc/technologies/radionuclide-generators-kits/), [Research reactors for medical isotopes (Mo-99, Lu-177, I-131)](https://nuclide.cc/technologies/research-reactor-isotope-production/), [SPECT & bone scan](https://nuclide.cc/technologies/spect/), [SPECT dosimetry workflow for radionuclide therapy](https://nuclide.cc/technologies/spect-dosimetry-workflow/), [SPECT/CT](https://nuclide.cc/technologies/spect-ct/), [Therapeutic isotope supply chain (Mo-99, Lu-177, Ac-225)](https://nuclide.cc/technologies/therapy-isotope-supply-chain/)
- companies: [BWXT Medical](https://nuclide.cc/companies/bwxt-medical/), [Cardinal Health Nuclear & Precision Health Solutions](https://nuclide.cc/companies/cardinal-health/), [Curium](https://nuclide.cc/companies/curium/), [Cyclopharm](https://nuclide.cc/companies/cyclopharm/), [GE HealthCare](https://nuclide.cc/companies/ge-healthcare/), [Lantheus](https://nuclide.cc/companies/lantheus/), [Navidea Biopharmaceuticals](https://nuclide.cc/companies/navidea/), [Niowave](https://nuclide.cc/companies/niowave/), [Quirem Medical](https://nuclide.cc/companies/quirem-medical/)
- indications: [Cardiac amyloidosis (transthyretin, ATTR-CM)](https://nuclide.cc/indications/cardiac-amyloidosis-attr/), [Coronary artery disease](https://nuclide.cc/indications/coronary-artery-disease/), [Functional assessment of thyroid nodules](https://nuclide.cc/indications/thyroid-nodule-assessment/), [Gastrointestinal bleeding localisation](https://nuclide.cc/indications/gastrointestinal-bleeding/), [Graves' disease and hyperthyroidism](https://nuclide.cc/indications/graves-hyperthyroidism/), [Non-small cell lung cancer](https://nuclide.cc/indications/nsclc/), [Prosthetic joint infection](https://nuclide.cc/indications/infection-prosthetic-joint/), [Pulmonary embolism: ventilation/perfusion imaging](https://nuclide.cc/indications/pulmonary-embolism-vq/), [Sentinel lymph node mapping in breast cancer and melanoma](https://nuclide.cc/indications/sentinel-node-mapping/), [Suspected upper urinary tract obstruction](https://nuclide.cc/indications/renal-obstruction/)
- institutions: [American Society of Nuclear Cardiology](https://nuclide.cc/institutions/asnc/), [Japanese Society of Nuclear Medicine](https://nuclide.cc/institutions/jsnm/)
- opportunities: [CAIX imaging of the indeterminate renal mass](https://nuclide.cc/opportunities/opp-caix-indeterminate-renal-mass/), [CEACAM5 imaging for occult colorectal recurrence](https://nuclide.cc/opportunities/opp-ceacam5-imaging-colorectal/)
- bottlenecks: [Enriched target material for therapeutic isotopes](https://nuclide.cc/bottlenecks/b-enriched-target-material/), [Molybdenum-99 supply](https://nuclide.cc/bottlenecks/b-mo99-supply/), [Reimbursement and coding for radiopharmaceuticals](https://nuclide.cc/bottlenecks/b-reimbursement-coding/)
- fronts: [Cardiac imaging](https://nuclide.cc/fronts/f-cardiac-imaging/), [Isotope supply](https://nuclide.cc/fronts/f-isotope-supply/), [Regulation & reimbursement](https://nuclide.cc/fronts/f-regulation-reimbursement/)
- roadmaps: [Isotope supply roadmap: reactor dependence → non-uranium production → accelerator-made actinium](https://nuclide.cc/roadmaps/isotope-supply-roadmap/)
- targets: [Bone mineral (hydroxyapatite)](https://nuclide.cc/targets/bone-hydroxyapatite/), [CCK2 receptor (gastrin receptor)](https://nuclide.cc/targets/cck2-receptor/), [Integrin αvβ3](https://nuclide.cc/targets/integrin-avb3/)
- terms: [Flare phenomenon](https://nuclide.cc/terms/flare-phenomenon/), [Hot lab (radiopharmacy dispensing area)](https://nuclide.cc/terms/hot-lab/), [Product release criteria (radiopharmaceutical quality control)](https://nuclide.cc/terms/release-criteria/), [Radiochemical purity (RCP)](https://nuclide.cc/terms/radiochemical-purity/), [Radionuclidic purity](https://nuclide.cc/terms/radionuclidic-purity/), [Radiopharmaceutical extravasation](https://nuclide.cc/terms/extravasation-radiopharmaceutical/), [Radiopharmacy (practice and discipline)](https://nuclide.cc/terms/radiopharmacy-term/)
- trials: [AURORA](https://nuclide.cc/trials/aurora-flurpiridaz/)

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