A new photon branch in the standard Panasonic UD-802 Dose Algorithm at the CIEMAT External Dosimetry Service

The standard dose algorithm provided by Panasonic to be used with the four element UD-802 TLD badge is widely employed in Personnel Dosimetry Services all around the world. The algorithm was developed to satisfy the obsolete standard ANSI 13.11-1983 that was reviewed in 1993 (HPS N13.11-1993) and revised again in 2001 (HPS N13.11-2001) including differences in the NIST x-ray techniques used as test spectra and updated values of the air kerma to dose equivalent conversion factors. In addition, the x-ray reference radiations employed in Spain and in most of the european countries for calibrating dosemeters are the specified in the ISO 4037-1 (1996) and the conversion coefficients from air kerma to dose equivalent are those given in the ISO 4037-3 (1999). All these conditions made necessary a deep revision of the photon correction factors and categories included in the photon branch of the standard UD-802 dose algorithm. With this aim, dosemeters from the CIEMAT External Dosimetry Service (EDS) were irradiated at the CIEMAT Reference Laboratory for X-ray at Protection Level employing the X-ray from the narrow-spectrum series given by the ISO 4037-1 (1996) and the ISO water slab phantom. The results allowed testing the energy response of the four element of the dosemeter, to define its real discrimination capability and to determine the correction factors that best accommodate the results to the reference doses. This process concluded with the proposal of a completely new photon branch in the standard UD-802 dose algorithm that has recently undergone a blind test to guarantee its performance. This work presents the proposal of the new photon branch and the comparison between the results of the blind test from both the modified and the standard UD-802 dose algorithm.