Roentgen (unit) capped at 3 MeV in 1950. The USSR all-union committee of standards (GOST) had meanwhile adopted a significantly different definition of the roentgen in 1934. GOST standard 7623 defined it as "the physical dose of X-rays which produces charges each of one electrostatic unit in magnitude per cm of irradiated volume in air at 0 °C and normal atmospheric pressure when ionization is complete." The distinction of physical dose from dose caused confusion, some of which may have led Cantrill and Parker report that the roentgen had become shorthand for 83 ergs per gram (0.0083 Gy) of tissue. They named
Roentgen (unit) Valentine Mayneord and the radiobiologist John Read, published a paper in which a unit of measure, dubbed the ""gram roentgen"" (symbol: gr) defined as "that amount of neutron radiation which produces an increment in energy in unit volume of tissue equal to the increment of energy produced in unit volume of water by one roentgen of radiation" was proposed. This unit was found to be equivalent to 88 ergs in air. In 1953 the ICRU recommended the rad, equal to 100 erg/g, as the new unit of measure of absorbed radiation. The rad was expressed in coherent cgs units. In