Technetium-99m is used in 20 million diagnostic nuclear medical
procedures every year. Approximately 85 percent of diagnostic
imaging procedures in nuclear medicine use this isotope. Technetium-
99m is made from the synthetic substance Molybdenum-99 which is a by-
product of nuclear fission. It is because of its parent nuclide,
that Technetium-99m is so suitable to modern medicine. Molybdenum-99
has a half-life of approximately 66 hours, and decays to Tc-99m, a
negative beta, and an antineutrino (see equation below). This is a
useful life since, once this product (molybdenum-99) is created, it
can be transported to any hospital in the world and would still be
producing technetium-99m for the next week. The betas produced are
easily absorbed, and Mo-99 generators are only minor radiation
hazards, mostly due to secondary X-rays produced by the betas.

99Mo (Negative Beta Decay) �� 99mTc + ��- + ��-
Where ��- = a negative beta particle (electron), and ��- = an
antineutrino.

99mTc will then undergo an isomeric transition to yield 99Tc and a
monoenergetic gamma emission.

99mTc �� 99Tc + ��
When a hospital receives a bottle of molybdenum-99, the technetium-
99m from within can be easily chemically extracted. That same bottle
of molybdenum-99 (holding only a few micrograms) can potentially
diagnose ten thousand patients because it will be producing
technetium-99m, strongly for over a week. The radioisotope is
perfect for medicinal purposes. The short half life of the isotope
allows for scanning procedures which collect data rapidly. The
isotope is also of a very low energy level for a gamma emitter. Its
~140 keV of energy make its use very safe and substantially reduce
the chance of ionization.