Energy dependency of a water-equivalent fibre-coupled beryllium oxide (BeO) dosimetry system

• The photon energy response of a fibre-coupled beryllium oxide (BeO) ceramic dosimeter, named RL/OSL BeO FOD was investigated.
• Under response of both the RL and OSL signals observed for lower x-ray energies.
• The RL signal shows a constant response for x-ray energies above a 50 kVp SXR beam.
• The OSL signal differs from the RL at higher photon energies, and shows an over response.
• Different intrinsic energy response is observed for the RL and OSL.

Here we investigate the energy dependency of the radioluminescence (RL) and optically stimulated luminescence (OSL) of near water equivalent beryllium oxide (BeO) ceramics. The BeO ceramic is coupled to an optical fibre. We investigate the water equivalence of BeO ceramics by comparing the mass attenuation coefficients and mass stopping powers of BeO ceramic to those of water. We also compare the results to other common dosimeter materials; polyvinyl toluene (PVT) based plastic scintillators, lithium fluoride (LiF) and aluminium oxide (Al2O3:C). Results show that while PVT based plastic scintillators are the most water equivalent material investigated, the mass attenuation coefficients and mass stopping power ratios of BeO and water vary the least with energy. We also investigate the x-ray energy dependence of BeO ceramic for a range of energies produced by a superficial x-ray unit (SXR), an Iridium-192 source and a high energy linear accelerator. Results indicate a significant under response of the BeO ceramic RL and OSL signals for lower x-ray energies, up to 55% for the lower SXR beams. The RL signal from BeO ceramics shows a constant response for x-ray energies above a 50 kVp SXR beam.