tc-99m pertechnetate

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Tc-99m pertechnetate (NaTc O4) is one of the technetium radiopharmaceuticals used in imaging of thyroid, colon, bladder and stomach.

Technetium (Tc) has eight oxidation states , from -1 to +7; specifically, the oxidation state of technetium in the pertechnetate anion (TcO4) is +7. The pertechnetate anion is, among the chemical species of technetium, the most stable in aqueous solution .

Characteristics

  • photon energy: 140 keV
  • protons: 43 (ie. atomic number)
  • physical half-life: 6 hours
  • biological half-life: ~ 1 day
  • 4.0 < pH < 8.0
  • radiochemical purity: > 95%
  • molecular geometry (pertechnetate anion): tetrahedral
  • normal distribution: stomach, thyroid, salivary glands, (testicles)
  • excretion: renal, GI
  • target organs: thyroid, colon, bladder, stomach, testicular (rarely performed)

Uses, doses and timings

Pediatric doses have been derived from various sources, a true international consensus remains work in progress.

  • Meckel diverticulum
    • adult dose: 370 MBq (10 mCi) IV
    • pediatric dose: 1.85 MBq/kg (0.05 mCi/kg)
      • minimum 9.25 MBq (0.25 mCi)
    • time of imaging: immediate (1 frame/s x 60 s then q 5-10 min x 1 hr)
  • parathyroid subtraction
    • adult dose:  37-74 MBq (1-2 mCi) IV
    • time of imaging: image for 15 minutes after Tl-201 injection and imaging
  • testicular
    • adult dose: 370 MBq (10 mCi) IV
    • pediatric dose: pending mCi/kg
      • minimum 185 MBq (5 mCi)
    • time of imaging: 60-second flow study with delayed static images
  • thyroid
    • adult dose: 37-370 MBq (1-10 mCi) IV
      • usually 111-185 MBq (3-5 mCi)
    • time of imaging: 20 minutes

History and etymology

Technetium was discovered in 1937 by C. Perrier and Emilio Segre at Palermo University. They managed to isolate technetium-97 from a sample of molybdenum irradiated with deuterons in the cyclotron of the University of Berkeley .

See also

Siehe auch:
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