Iodine-123
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Iodine-123 is a radioactive isotope of iodine often used in single photon emission computed tomography (SPECT). Its half-life is 13.13 hours; the decay emits gamma radiation, and in medical applications this radiation can be detected by a SPECT-scanner.
[edit] Medical application
Typically iodine-123 is ingested in the form of a capsule;[citation needed] the patient is later imaged by a nuclear gamma camera. Areas where the radioactive iodine (called radio-iodine) concentrates will show up on the nuclear gamma camera.
Iodine-123 is most commonly used to detect cancers of the thyroid, as this is the organ most receptive to forms of iodine.[citation needed] Once the thyroid has absorbed the radio-iodine, any cancer present will have a differing uptake of radio-iodine than the natural, surrounding tissue. This difference can be analyzed by a doctor to determine whether there exists a possibility for thyroid cancer. A tissue biopsy obtained via Fine Needle Aspiration (FNA) may also be performed to further determine whether it is cancerous or not, and whether it is malignant or benign.
