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This chain of decay was later shown to have the mass number 99, and (...) the 6.6-h activity acquired the designation ‘technetium-99m. Later in 1940, Emilio Segrè and Chien-Shiung Wu published experimental results of an analysis of fission products of uranium-235, including molybdenum-99, and detected the presence of an isomer of element 43 ...
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.
Technetium-99m's short half-life of 6 hours makes long-term storage impossible. Transport of 99m Tc from the limited number of production sites to radio pharmacies (for manufacture of specific radiopharmaceuticals ) and other end users would be complicated by the need to significantly overproduce to have sufficient remaining activity after long ...
For technetium-98 and heavier isotopes, the primary mode is beta emission (the emission of an electron or positron), producing ruthenium (Z = 44), with the exception that technetium-100 can decay both by beta emission and electron capture. [59] [60] Technetium also has numerous nuclear isomers, which are isotopes with one or more excited nucleons.
A DPD scan is a type of nuclear medicine imaging test which uses radioactive technetium-99m (99m Tc) and 3,3-diphosphono-1,2-propanodicarboxylic acid (DPD) to diagnose cardiac amyloidosis. The radiopharmaceutical is taken up only in patients with ATTR amyloidosis , making it a useful tool to differentiate from AL amyloidosis .
It decays by beta-decay with a half-life of 87.51 days. It is used to label the sulfur-containing amino-acids methionine and cysteine . When a sulfur atom replaces an oxygen atom in a phosphate group on a nucleotide a thiophosphate is produced, so 35 S can also be used to trace a phosphate group.
The test was first introduced in 1956, using iodine-131 diodrast. [25] [26] Later developments included iodine-131, and then iodine-123, labelled ortho-Iodohippuric acid (OIH, marketed as Hippuran). [27] [28] 99m Tc-MAG3 has replaced 131 I-OIH because of better quality imaging regardless of the level of kidney function, [29] and lower radiation ...
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.