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 Dürr the Younger assistant professor at the Munich Academy of Fine Arts and, in 1892, professor. There he taught mainly life classes. At the end of his life, he was seriously ill and only painted a few pictures. In Dachau, Wilhelm-Dürr-Straße is named in honour of the painter. Wilhelm Dürr the Younger Wilhelm Dürr the Younger (24 August 1857, Freiburg im Breisgau, Baden – 23 February 1900, Munich) was a German painter and draughtsman, as well as a professor at the Academy of Fine Arts in Munich. Dürr was the son of the painter Wilhelm Dürr the Elder (1815–1890) and his wife Berta