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
Carl August Wilhelm Berends junger Ärzte am Krankenbett" (Education of Young Physicians at the Bedside), in which he described his experiences at the Thielschen Krankenhaus in Frankfurt. Shortly after his death in 1826, his one-time student, Karl Sundelin, published Berends' lectures on practical medical science (""Vorlesungen über die praktische Arzneiwissenschaft""). Carl August Wilhelm Berends Carl August Wilhelm Berends (April 19, 1759 – December 1, 1826) was a German physician born in Anklam, Pomerania. He studied medicine at Viadrina University in Frankfurt an der Oder, where in 1788 he became a professor of medicine. In 1811 he moved to the University of Breslau, being due