Roentgen (unit) this derivative quantity the roentgen equivalent physical (rep) to distinguish it from the ICR roentgen. The introduction of the roentgen measurement unit, which relied upon measuring the ionisation of air, replaced earlier less accurate practices that relied on timed exposure, film exposure, or fluorescence. This led the way to setting exposure limits,and the National Council on Radiation Protection and Measurements of the United States established the first formal dose limit in 1931 as 0.1 roentgen per day. The International X-ray and Radium Protection Committee, now known as the International Commission on Radiological Protection (ICRP) soon followed with a limit of
Wilhelm Olivier Leube Wilhelm Olivier Leube Wilhelm Olivier Leube (14 September 1842 – 16 May 1922) was a German internist born in Ulm. He studied medicine in Tübingen, Zurich, Berlin and Munich, and from 1868 worked as an assistant at the medical clinic in Erlangen. In 1872, at the University of Jena, he became a professor of pathology and special therapy, as well as director of the medical clinic. At Jena, one of his assistants was noted physician Ottomar Rosenbach (1851–1907). Afterwards he was a professor at the Universities of Erlangen (1874–1885) and Würzburg, where in 1895/96 he served as university rector. Wilhelm