History of medical physics.

Medical physics began with the development of safe handling of radium, such as protecting medical personnel from radiation when radium radiation is used to treat cancer. By the end of World War II, the field of medical physics had expanded to the development of safe and reliable treatments for cancer with radiation and quantification of radiation dose, which is called dosimetry that is required to evaluate the therapeutic effect. The rapid development of nuclear technology during World War II made it possible to use large amounts of radioisotopes (RI) produced in nuclear reactors, and the medical use of RI gave birth to clinical nuclear medicine. Since knowledge and skills in radiation measurement and RI handling were required for the development and clinical use of its equipment, nuclear medicine physics was added to medical physics after the war. The invention of computed tomography (CT) in 1972 had a great impact on clinical medicine, while the development of magnetic resonance imaging (MRI) began around that time. As a result, the development of CT and MRI, as well as the study of their image characteristics, which had not necessarily been regarded as the field of medical physics before, was added to that field as radiation diagnostic physics. This review outlines the history of developments in medical physics, and touches on the first medical physicists in Europe and the United States. It also briefly explains the beginning of medical physics and the world-class medical physics achievements in Japan.