This document specifies the procedures for the dosimetry of X and gamma reference radiation for the
calibration of radiation protection instruments over the energy range from approximately 8 keV to
1,3 MeV and from 4 MeV to 9 MeV and for air kerma rates above 1 μGy/h. The considered measuring
quantities are the air kerma free-in-air, Ka, and the phantom related operational quantities of the
International Commission on Radiation Units and Measurements (ICRU)[2], H*(10), Hp(10), H'(3), Hp(3),
H'(0,07) and Hp(0,07), together with the respective dose rates. The methods of production are given
in ISO 4037-1.
This document can also be used for the radiation qualities specified in ISO 4037-1:2019, Annexes A, B
and C, but this does not mean that a calibration certificate for radiation qualities described in these
annexes is in conformity with the requirements of ISO 4037.
The requirements and methods given in this document are targeted at an overall uncertainty (k = 2)
of the dose(rate) of about 6 % to 10 % for the phantom related operational quantities in the reference
fields. To achieve this, two production methods of the reference fields are proposed in ISO 4037-1.
The first is to produce “matched reference fields”, which follow the requirements so closely that
recommended conversion coefficients can be used. The existence of only a small difference in the
spectral distribution of the “matched reference field” compared to the nominal reference field is
validated by procedures, which are given and described in detail in this document. For matched
reference radiation fields, recommended conversion coefficients are given in ISO 4037-3 only for
specified distances between source and dosemeter, e.g., 1,0 m and 2,5 m. For other distances, the user
has to decide if these conversion coefficients can be used.
The second method is to produce “characterized reference fields”. Either this is done by determining the
conversion coefficients using spectrometry, or the required value is measured directly using secondary
standard dosimeters. This method applies to any radiation quality, for any measuring quantity and,
if applicable, for any phantom and angle of radiation incidence. The conversion coefficients can be
determined for any distance, provided the air kerma rate is not below 1 μGy/h.
Both methods require charged particle equilibrium for the reference field. However this is not always
established in the workplace field for which the dosemeter shall be calibrated. This is especially true
at photon energies without inherent charged particle equilibrium at the reference depth d, which
depends on the actual combination of energy and reference depth d. Electrons of energies above 65 keV,
0,75 MeV and 2,1 MeV can just penetrate 0,07 mm, 3 mm and 10 mm of ICRU tissue, respectively, and
the radiation qualities with photon energies above these values are considered as radiation qualities
without inherent charged particle equilibrium for the quantities defined at these depths.
This document is not applicable for the dosimetry of pulsed reference fields.