sodium 24

so·di·um 24 (24Na),

(sō'dē-ŭm), The isotope of sodium with an atomic weight of 24, and a half-life of 14.96 hr; it emits beta and gamma rays, and is more easily prepared than the longer-lived, positron-emitting 22Na (half-life, 2.605 year). It is used to measure extracellular fluid by indicator dilution.