Radioisotopes use in medicine

Since that time, hundreds of radioisotopes have been produced in the laboratory. In order for charged particles like a-particles to penetrate a positively charged nucleus, or the electron cloud surrounding the nucleus, they must be moving at extremely high velocities. Such velocities are achieved in particle accelerators such as the cyclotron. All the elements above atomic number 92 have been created in this manner. Most radioisotopes used in medicine have been produced using neutrons as subatomic projectiles. 

Compounds labeled with isotopes have played an important role in chemistry, biology, and medicine since they were first used as tracers by Hevesey. - Both stable - and radioactive isotopes were utilized in early investigations, but the situation changed dramatically with the invention of the cyclotron by Lawrence in 1930 and the construction of the nuclear reactor by Fermi in 1942 that enabled access to radioisotopes on a regular basis. Radioisotope use in medicine was also accelerated by advances in radiation-detection techniques. The development of single-photon emission computerized tomography (SPECT) " and positron emission tomography revolutionized... 

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