Medical radioisotopes are used for the diagnosis and for treatment of several illnesses. Currently there are in Europe over 12 million medical procedures per using radioisotopes. About 90% of radioisotopes are used for diagnostic purposes and 10% for therapies. Principle Radioisotopes usage relies on the injection into the patient of a radionuclide combined with a biologically active molecule which preferentially localizes specific organs, cells or tumors for therapeutic purpose. The radionuclide decays emitting highly ionization particles which will destroy the malignant cells. When used for imaging purpose, radioisotopes emit gamma radiations which are detected from the outside, using single-photon emission computed tomography (SPECT) and positron emission tomography (PET), a 3D image being reconstructed by a computer.