Determination of conversion factors from air kerma to operational dose equivalent quantities for low-energy X-ray spectra

Abstract

The conversion coefficients from air kerma to ICRU operational dose equivalent quantities for STUK's realisation of the X-radiation qualities N-15 to N-60 of the ISO narrow (N) spectrum series were determined by utilising X-ray spectrum measurements. The pulse-height spectra were measured using a planar high-purity germanium spectrometer and unfolded to fluence spectra using Monte Carlo generated data of the spectrometer response. To verify the measuring and unfolding method, the first and second half-value layers and the air kerma rate were calculated from the fluence spectra and compared with the values measured using an ionisation chamber. For each radiation quality, the spectrum was characterised by the parameters given in ISO 4037-1. The conversion coefficients from the air kerma to the ICRU operational quantities Hp(10), Hp(0.07), H'(0.07) and H*(10) were calculated using monoenergetic conversion coefficients at zero angle of incidence. The results are discussed with respect to ISO 4037-4, and compared with published results for low-energy X-ray spectra.

Calibration and measurement of X-ray personal dose equivalent with a Hp(10) ionization chamber

“…For filtered X radiation, the recommend conversion coefficients are listed in ISO 4307-3. Although the X-ray radiation quality established by different X-ray facilities meets the standard requirements, the spectral distributions will be a little different, especially for low energy photons [18]. Because the change of energy distribution may have a great influence on the value of conversion coefficient, it is the best way to measure personal dose equivalent directly with a secondary standard ionization chamber which is calibrated without considering the influence of low-energy photon spectrum in the range of uncertainty.…”

X-ray spectrometry for calculating conversion coefficients from air kerma to operational quantities in radiation protection

“…A few years later, Hakanen et al [5] focused on low-energy spectra (N-15 to N-60 x-ray qualities), determining conversion factors from air kerma to operational dose equivalent quantities. Their study contributed significantly to the understanding of conversion factors for low-energy photons, which are particularly relevant in medical and industrial applications.…”