Cesium Cs-131

**Semantic type:** Element, Ion, or Isotope

**Definition:** An unstable radioisotope of cesium (Cs) with radiocytotoxic application. Cs-131 is a gamma photon-emitting radionuclide with high energy and a relatively short half-life of 9.7 days. When used in prostate brachytherapy, Cs-131 demonstrated advantages over other commonly used isotopes.

**Synonyms:** - 131-Cs - CESIUM CS-131