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
Dietrich Wilhelm Heinrich Busch Dietrich Wilhelm Heinrich Busch Dietrich Wilhelm Heinrich Busch (16 March 1788 – 15 March 1858) was a German obstetrician born in Marburg. In 1806 he earned his medical doctorate at the University of Marburg, becoming an associate professor of surgery in 1814. In 1817 he was appointed professor of obstetrics at Marburg, where from 1820 to 1829 he was director of the department of obstetrics. In 1829 he succeeded Adam Elias von Siebold (1775-1828) as professor and director of the obstetrics clinic at Friedrich Wilhelm University in Berlin, serving as university rector in 1835/36. He would remain as director of