Recommendations of the International Commission on Radiological Units

Abstract

HomeRadiologyVol. 62, No. 1 PreviousNext EditorialRecommendations of the International Commission on Radiological UnitsRevised at the Seventh International Congress of Radiology, Copenhagen, July 1953Published Online:Jan 1 1954https://doi.org/10.1148/62.1.106MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In AbstractI. Definitions and Units1. Intensity of radiation is the energy flowing through unit area perpendicular to the beam per unit time. It is expressed in ergs per square centimeter per second or watts per square centimeter.2. Quantity of radiation is the time integral of intensity. It is the total energy which has passed through unit area perpendicular to the beam and is expressed in ergs per square centimeter or watt-seconds per square centimeter.3. Absorbed dose of any ionizing radiation is the amount of energy imparted to matter by ionizing particles per unit mass of irradiated material at the place of interest. It shall be expressed in rads.4. The rad is the unit of absorbed dose and is 100 ergs per gram.5. Inasmuch as calorimetric methods of determining absorbed dose are not usually practicable, ionization methods are generally employed. The quantity which must be measured is the ionization produced in a gas by the same flow of corpuscular radiation as exists in the material under consideration. The energy, Em, imparted to unit mass of the material is then essentially related to the ionization per unit mass of gas, Jm, by the equation Em = WsJm where W is the average energy expended by the ionizing particles per ion pair formed in the gas, and s is the ratio of the mass stopping power of the material to that of the gas.6. Since the calculation of the absorbed dose from measurements of ionization requires a knowledge of the parameters W and s as well as variables characterizing the radiation and the irradiated material it is recommended that tables of the best available data be prepared and held under continual review.17. The roentgen (r) remains the unit of x-and γ-ray dose and its definition remains unchanged as below: The roentgen shall be the quantity of x- or γ-radiation such that the associated corpuscular emission per 0.001293 gram of air produces, in air, ions carrying 1 electrostatic unit of quantity of electricity of either sign.8. It becomes increasingly difficult to measure the dose in roentgens as the quantum energy of the x- or γ-radiation approaches very high values. The unit may, however, be used for most practical purposes for quantum energies up to 3 Mev.9. Integral absorbed dose is the integration of the energy absorbed throughout a given region of interest. The unit is the gram-rad. 1 gram-rad = 100 ergs.10. Amounts of radioactive material shall be expressed in curies. The accepted definition of the curie is: The curie is a unit of radioactivity defined as the quantity of any radioactive nuclide in which the number of disintegrations per second is 3.700 × 1010.11. With this definition the curie is independent of the disintegration rate of radium.12. It is suggested that the γ-ray emission be expressed in terms of roentgens per millicurie-hour at 1 cm. from a point source. This quantity is different for every isotope. Preliminary data have been compiled relating to a number of radioactive isotopes and will be supplemented from time to time.1Article HistoryPublished in print: Jan 1954 FiguresReferencesRelatedDetailsCited ByMicrodosimetry and nanodosimetry for internal emittersW.B.Li, W.Hofmann, W.Friedland2018 | Radiation Measurements, Vol. 115ReferencesL. A.Braby, A. L.Brooks, W. F.Heidenreich, M. A.Hill, R. W.Howell, K.Kobayashi, W. E.Wilson, M.Zaider2011 | Journal of the ICRU, Vol. 11, No. 2Chapters 1 and 22007 | Annals of the ICRP, Vol. 37, No. 2-4Annex B and All references2007 | Annals of the ICRP, Vol. 37, No. 2-4On the biophysical interpretation of the mathematical product of dose and relative biological effectivenessG K YLam1990 | Physics in Medicine and Biology, Vol. 35, No. 4International work on the metrology of ionizing radiationM. F.Yudin, Yu. I.Bregadze1975 | Measurement Techniques, Vol. 18, No. 4Engineering Compendium on Radiation ShieldingH. O.Wyckoff, H. H.Rossi, J.Mehl, N. G.Goussev1968The definition of the roentgen in the ?Recommendations of the International Commission on Radiological Units. 1953?S. N.Ardashnikov, N. S.Chetverikov1957 | The Soviet Journal of Atomic Energy, Vol. 3, No. 9The Biochemistry and Physiology of BoneJANET M.VAUGHAN1956Recommended Articles RSNA Education Exhibits RSNA Case Collection Vol. 62, No. 1 Metrics Altmetric Score PDF download