Therapy of Hepatocellular Carcinoma with Iodine-131-Lipidiol

Therapy in nuclear medicine practice has a long distinguished history. Nuclear medicine therapy is required to be highly specific and targeted, since it always involves administration of unsealed sources of radioactivity. Most therapy agents utilize ß-particle emissions for their ability to penetrate tissues. This deposition of energy in tissue by ß emitters results in cellular damage. Among the ß emitters there are several choices with respect to energy of the ß emission. Lower energy ß particles can travel a few cell diameters, or at most in the sub-millimeter range. Higher energy ß particles such as those emitted by Y90 have an excellent tissue penetration with a range beyond the source of several millimeters. The physical half-life of the therapeutic radionuclide is an important consideration and underlying principle for therapy planning. Rarely, except in thyroid treatment, is the simple salt form of the radionuclide used. It is most likely attached to a drug or particle that controls its biodistribution. The ideal therapeutic radiopharmaceutical is one that remains attached to the parent drug or its metabolites, and is excreted rapidly through a known simple route1.