Therapeutic radiopharmaceuticals

A variety of radiopharmaceuticals have been introduced for the internal the rapy of malignant and inflammatory lesions in nuclear medicine. In order to destroy the disseased tissues radionuclides with high linear energy transf er (LET) such as beta, alpha, Auger or low energy conversion electron emitt ers are needed. The range of beta particles is in mm's so they are effectiv e for large tumors. The range of alpha particles is short, only a few cell diameters. Thus, they are effective in treating circulating malignant cells and micrometastases, The range of Auger and conversion electrons is <0.1 m u m. They are very effective in cell killing when they are carried across c ell membrane into the nucleus to damage DNA. Appropriate ions, molecules an d particles are labelled with such radionuclides and used as radiopharmaceu ticals in many different applications. For an effective dose to be delivere d high target to non target ratios must be attained. Monoclonal antibodies to specific antigens expressed on tumor cells have been developed to increa se the uptake by malignant tissues by specific accumulation. Radiolabelled peptides such as somatostatin, small molecules such as metaiodo-benzylguani dine (MIBG) and many different nano-and micro-particles have been investiga ted. The effectiveness of therapy can be increased by direct locoregional a dministration of the radiopharmaceutical. This way the radiation effects ar e confined locally and the normal tissues an spared from radiation effects. In this review article selection criteria and characteristics of radionucli des and carrier ions, molecules and particles for various therapeutic appli cations will be discussed, including mainly the recent developments.