Thallium-201 chloride

Thallium-201 chloride (TlCl) is a radiopharmaceutical used primarily in cardiac imaging. Thallium-201 is an analog of potassium; it is produced in cyclotron by bombarding thallium-203 with protons.


  • thallium is a monovalent cation
  • photon energy: 68-80 keV (a smaller amount of γ-rays at 137 and 167 keV)
  • physical half life: 73 hours
  • biological half life
    • rest: 3 minutes
    • exercise: 30 seconds
  • normal distribution: myocardium, skeletal muscle, GI tract, liver, kidneys
  • excretion: renal
  • target organ: kidneys
  • pharmacokinetics:
  • miscellaneous facts: 
    • more background noise than MUGA
    • 201Tl-cerebral SPECT can be used to differentiate toxoplasmosis vs lymphoma (increased uptake in lymphoma, decreased in toxoplasmosis)

Uses, doses and timings

Cardiac scan
  • adult dose: 55.5 MBq (1.5 mCi) IV
Imaging technology

Article information

rID: 24811
Synonyms or Alternate Spellings:
  • Tl 201 chloride
  • Thallous chloride

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