The International Commission on Radiation Units and Measurements (ICRU) is a standardization body set up in 1925 by the International Congress of Radiology, originally as the X-Ray Unit Committee until 1950. Its objective "is to develop concepts, definitions and recommendations for the use of quantities and their units for ionizing radiation and its interaction with matter, in particular with respect to the biological effects induced by radiation". During the first two decades of its existence, its formal meetings were held during the International Congress of Radiology, but from 1950 onwards, when its mandate was extended, it has met annually.
Until 1953, the president of the ICRU was a national of the country that was hosting the ICR, but in that year it was decided to elect a permanent commission - the first permanent chairman being Laurent Taylor who had been a member of the commission since 1928 and secretary since 1934. Taylor served until 1969 and on his retirement was accorded the position of honorary chairman which we held until his death in 2004, aged 102.
The commission has a maximum fifteen members who serve for four years and who, since 1950, have been nominated by the incumbent commissioners. Members are selected for their scientific ability and is widely regarded as the foremost panel of experts in radiation medicine and in the other fields of ICRU endeavor. The commission is funded by the sale of reports, by grants from the European Commission, the US National Cancer Institute and the International Atomic Energy Agency and indirectly by organisations and companies who provide meeting venues. Commissioners, many of whom have full-time university or research centre appointments, have their expenses reimbursed, but otherwise they receive no remuneration from the ICRU.
In the late 1950s the ICRU was invited by the CGPM to join other scientific bodies to work with the International Committee for Weights and Measures (CIPM) in the development of a system of units that could be used consistently over many disciplines. This body, initially known as the "Commission for the System of Units" (renamed in 1964 as the "Consultative Committee for Units") was responsible overseeing the development of the International System of Units (SI).
In the late 1950s the ICRU started publishing reports on an irregular basis - on average two to three a year. In 2001 the publication cycle was regularised and reports are now published bi-annually under the banner "Journal of the ICRU".
The commission has been responsible for defining and introducing the following units of measure on behalf of the industry. The number of different units for various quantities is indicative of changes of thinking in world metrology, especially the movement from cgs to SI units.
| Quantity | Name | Symbol | Unit | Year |
|---|---|---|---|---|
| Exposure (X) | röntgen | R | esu / 0.001293 g of air | 1928 |
| Absorbed dose (D) | erg•g−1 | 1950 | ||
| rad | rad | 100 erg•g−1 | 1953 | |
| gray | Gy | J•kg−1 | 1974 | |
| Activity (A) | curie | c | 3.7 × 1010 s−1 | 1953 |
| becquerel | Bq | s−1 | 1974 | |
| Dose equivalent (H) | röntgen equivalent man | rem | 100 erg•g−1 | 1971 |
| sievert | Sv | J•kg−1 | 1977 | |
| Fluence (Φ) | (reciprocal area) | cm−2 or m−2 | 1962 |
The Commission's secretariat is in Stockholm and its legal status is that of British charity (Not-for-profit organisation).
Famous quotes containing the words commission, radiation and/or units:
“Children cannot eat rhetoric and they cannot be sheltered by commissions. I don’t want to see another commission that studies the needs of kids. We need to help them.”
—Marian Wright Edelman (20th century)
“There are no accidents, only nature throwing her weight around. Even the bomb merely releases energy that nature has put there. Nuclear war would be just a spark in the grandeur of space. Nor can radiation “alter” nature: she will absorb it all. After the bomb, nature will pick up the cards we have spilled, shuffle them, and begin her game again.”
—Camille Paglia (b. 1947)
“Even in harmonious families there is this double life: the group life, which is the one we can observe in our neighbour’s household, and, underneath, another—secret and passionate and intense—which is the real life that stamps the faces and gives character to the voices of our friends. Always in his mind each member of these social units is escaping, running away, trying to break the net which circumstances and his own affections have woven about him.”
—Willa Cather (1873–1947)