ABSTRACT
Wilhelm Roentgen discovered x-rays in 1895, and Henri Becquerel discovered natural radioactivity in 1896. Marie and Pierre Curie discovered radium and polonium in 1898. Anderson discovered the positron in 1932, and two years later, Frederic and Irene Curie discovered artificial radioactivity. The same year, Lawrence invented the cyclotron. Those events marked the beginning of radiology and nuclear medicine (NM), two specialties that, at present, lend mankind invaluable service in the alleviation of many illnesses. As the nature and properties of those ionizing radiations were unknown in the early days, many persons were injured while working with xray machines and handling radioactive materials.
