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
David Roentgen David Roentgen David Roentgen (1743 in HerrnhaagFebruary 12, 1807), was a famous German cabinetmaker of the eighteenth century, famed throughout Europe for his marquetry and his secret drawers and mechanical fittings. His work embraces the late Rococo and the Neoclassical styles. In 1753 his father Abraham Roentgen, who had trained in London in the workshop of William Gomm, migrated to the Moravian settlement at Neuwied, near Coblenz, where he established a furniture factory. David learned his trade in his father's workshop, inherited the paternal business in 1772, and entered into partnership with the clockmaker Kintzing. By that time, the name