Absorbed dose

The SI unit of measure is the gray (Gy), which is defined as one Joule of energy absorbed per kilogram of matter.

The time between exposure and vomiting may be used as a heuristic for quantifying a dose when more precise means of testing are unavailable.

[4] (33.97 eV per ion pair) Therefore, an exposure of 2.58×10−4 C/kg (1 roentgen) would deposit an absorbed dose of 8.76×10−3 J/kg (0.00876 Gy or 0.876 rad) in dry air at those conditions.

Where For stochastic radiation risk, defined as the probability of cancer induction and genetic effects occurring over a long time scale, consideration must be given to the type of radiation and the sensitivity of the irradiated tissues, which requires the use of modifying factors to produce a risk factor in sieverts.

Wilhelm Röntgen first discovered X-rays on November 8, 1895, and their use spread very quickly for medical diagnostics, particularly broken bones and embedded foreign objects where they were a revolutionary improvement over previous techniques.

This was called the International Commission on Radiation Units and Measurements, or ICRU,[a] and came into being at the Second ICR in Stockholm in 1928, under the chairmanship of Manne Siegbahn.

This unit of radiation exposure was named the roentgen in honour of Wilhelm Röntgen, who had died five years previously.

[12] In 1940, Louis Harold Gray, who had been studying the effect of neutron damage on human tissue, together with William Valentine Mayneord and the radiobiologist John Read, published a paper in which a new unit of measure, dubbed the "gram roentgen" (symbol: gr) was proposed, and 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".

[11] In the late 1950s, the CGPM invited the ICRU to join other scientific bodies to work on the development of the International System of Units, or SI.

Absorbed dose is also used to manage the irradiation and measure the effects of ionising radiation on inanimate matter in a number of fields.

Absorbed dose is used to rate the survivability of devices such as electronic components in ionizing radiation environments.