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Technetium-99m (Tc-99m) can be readily detected in the body by medical equipment because it emits 140.5 keV gamma rays (these are about the same wavelength as emitted by conventional X-ray diagnostic equipment), and its half-life for gamma emission is six hours (meaning 94% of it decays to 99 Tc in 24 hours). Besides, it emits virtually no beta ...
The metastable technetium-99m (99m Tc) is a short-lived (half-life about 6 hours) nuclear isomer used in nuclear medicine, produced from molybdenum-99. It decays by isomeric transition to technetium-99, a desirable characteristic, since the very long half-life and type of decay of technetium-99 imposes little further radiation burden on the body.
97m Tc is the most stable, with a half-life of 91.0 days (0.097 MeV). [4] This is followed by 95m Tc (half-life: 61 days, 0.038 MeV) and 99m Tc (half-life: 6.04 hours, 0.143 MeV). 99m Tc only emits gamma rays, subsequently decaying to 99 Tc. [7] For isotopes lighter than 98 Tc, the primary decay mode is electron capture to isotopes of molybdenum.
Technetium (99m Tc) sestamibi is a lipophilic cation which, when injected intravenously into a patient, distributes in the myocardium proportionally to the myocardial blood flow. Single photon emission computed tomography imaging of the heart is performed using a gamma camera to detect the gamma rays emitted by the technetium-99m as it decays.
The half-life of 99 Tc is far longer than its metastable isomer, so the ratio of 99 Tc to 99m Tc increases over time. Both isomers are carried out by the elution process and react equally well with the ligand, but the 99 Tc is an impurity useless to imaging (and cannot be separated).
In particular it is used to carry the 99m Tc isotope (half-life 6 hours) which is commonly used in nuclear medicine in several nuclear scanning procedures. Pertechnetate is poorly hydrated as [TcO 4 (H 2 O) n ] − and [TcO 4 (H 2 O) n-m ] − [H 3 O] + m (n = 1–50, m = 1–4) clusters that have been demonstrated by simulation with DFT.
The radioactive 99m Tc O − 4 anion is an important radiopharmaceutical for diagnostic use. The advantages to 99m Tc include its short half-life of 6 hours and the low radiation exposure to the patient, which allow a patient to be injected with activities of more than 30 millicuries. [3] Na[99m Tc O
Radioactive isotope table "lists ALL radioactive nuclei with a half-life greater than 1000 years", incorporated in the list above. The NUBASE2020 evaluation of nuclear physics properties F.G. Kondev et al. 2021 Chinese Phys. C 45 030001. The PDF of this article lists the half-lives of all known radioactives nuclides.