Roentgen (unit) Roentgen (unit) The roentgen or röntgen () (symbol R) is a legacy unit of measurement for the exposure of X-rays and gamma rays. It is defined as the electric charge freed by such radiation in a specified volume of air divided by the mass of that air. In 1928 it was the first international measurement quantity for ionising radiation to be defined for radiation protection, and was an easily replicated method of measuring air ionization directly by using an ion chamber. It is named after the German physicist Wilhelm Röntgen, who discovered X-rays. Although relatively easy to measure, it had
Wilhelm Feldberg of the Royal Society in 1947 and made a Commander of the Order of the British Empire in 1963. Wilhelm Feldberg assisted many research workers who came to England as a part of their Commonwealth Medical Fellowship and Wellcome Research Fellowship. Under this Fellowships, Professor PN Saxena and Prof. KP Gupta of the Department of Pharmacology, Jawaharlal Nehru Medical College, Aligarh Muslim University, during the 1970s got many papers published together with Wilhelm Feldberg while their vocation at National Institute for Medical Research, Mill Hill. Feldberg's career was ended in 1990 when two animal rights activists gained access to his