| Abstract | [Important Parameters] I only will cover those parameters which are important for radioisotopes in diagnostic applications. These are the energy of the gamma photon that is emitted, the effective half life, the decay scheme for the nuclide, the selectivity for a specific organ or tissue and production capabilities. Some information will be given for newer isotopes used in nuclear medicine. These include indium-113m, technetium-99m, xenon-133, iodine-125 and cesium-131. Iodine-131 was the first important isotope used for scanning. This nuclide has a gamma photon energy of 360 kev, and this is still an excellent energy for diagnostic work. The energy range considered suitable for scanning with present equipment is 100 kev to 600 kev. Gamma photons with energies below 100 kev lack sufficient energy to effectively penetrate large thicknesses of tissue. Thus, anomalies deep within the body may be difficult to detect. However, for low energy species, such as cesium-131 (30 kev), or iodine-125 (27.4 kev), the use of newer devices, such as the image amplifier, produce good scans. |
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