Roentgen (unit) One roentgen deposits of absorbed dose in dry air, or in soft tissue. One roentgen of X-rays may deposit anywhere from in bone depending on the beam energy. This tissue-dependent conversion from kerma to absorbed dose is called the F-factor in radiotherapy contexts. The conversion depends on the ionizing energy of a reference medium, which is ambiguous in the latest NIST definition. The roentgen has its roots in the Villard unit defined in 1908 by the American Roentgen Ray Society as "the quantity of radiation which liberates by ionisation one esu of electricity per cm of air under normal conditions
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