BS ISO 4037-3:2019 pdf free.Radiological protection – X and gamma reference radiation for calibrating dosemeters and doserate meters and for determining their response as a function of photon energy.
For the tables in Clauses 6 and 8, the irradiation distance is measured from the focal spot of the X-ray tube (or from the geometrical centre of the radio nuclide source) to the point of test, at which the reference point of the dosemeter shall be located. For the R-C and R-F radiations, the irradiation distance shall be measured from the centre of the target surface from which the radiation emerges to the point of test. For the X-radiation qualities, recommended conversion coefficients are given, if available, for two distances of 1,0 m and 2,5 m in separate columns, even if they differ only by the last digit. This shall avoid the introduction of additional uncertainties. If these recommended conversion coefficients are identical for both distances, then the two table cells are merged and only one recommended conversion coefficient is given. This indicates that the recommended conversion coefficient can be used at least for distances from 1 m to 2,5 m. If the recommended conversion coefficients are different for the distances of 1 m and 2,5 m and a recommended conversion coefficient is required for other distances, then the given values of the recommended conversion coefficients shall be interpolated or extrapolated accordingly. If both values are very similar, e.g., only different by 2 % or less, then a linear interpolation may be used. If a range is given for the distance, then the values of the recommended conversion coefficients may be used without modification over this range of distances. From the available data in the Tables, it can be concluded that for collimated beams with mean energies above about 40 keV there is no difference in the recommended conversion coefficients for both distances. The difference increases with decreasing photon energy, increasing definition depth, increasing width of the spectra and increasing angle of radiation incidence. BS ISO 4037-3 pdf download.