LiF:Mg,Ti TLD response as a function of photon energy for moderately filtered x‐ray spectra in the range of 20–250 kVp relative to C 60 o
Author(s) -
Nunn A. A.,
Davis S. D.,
Micka J. A.,
DeWerd L. A.
Publication year - 2008
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.2898137
Subject(s) - kerma , thermoluminescent dosimeter , dosimeter , photon , photon energy , physics , optics , range (aeronautics) , irradiation , dosimetry , x ray , thermoluminescence , materials science , radiation , nuclear medicine , nuclear physics , medicine , composite material
The response of LiF:Mg,Ti thermoluminescent dosimeters (TLDs) as a function of photon energy was determined using irradiations with moderately filtered x‐ray beams in the energy range of 20–250 kVp relative to the response to irradiations withC60 o photons. To determine if the relative light output from LiF:Mg,Ti TLDs per unit air kerma as a function of photon energy can be predicted using calculations such as Monte Carlo (MC) simulations, measurements from the x‐ray beam irradiations were compared with MC calculated results, similar to the methodology used by Davis et al. [Radiat. Prot. Dosim. 106, 33–43 (2003)]. TLDs were irradiated in photon beams with well‐known air kerma rates using the National Institute of Standards and Technology traceable M‐series x‐ray beams in the range of 20–250 kVp. For each x‐ray beam, several sets of TLDs were irradiated for times corresponding to different air kerma levels to take into account any dose nonlinearity. TLD light output was then compared to that from several sets of TLDs irradiated at similar corresponding air kerma levels using aC60 o irradiator. The MC code MCNP5 was used to account for photon scatter and attenuation in the holder and TLDs and was used to calculate the predicted relative TLD light output per unit air kerma for irradiations with each of the experimentally used photon beams. The measured relative TLD response as a function of photon energy differed by up to 13 % from the MC calculations. We conclude that MC calculations do not accurately predict the relative response of TLDs as a function of photon energy, consistent with the conclusions of Davis et al. [Radiat. Prot. Dosim. 106, 33–43 (2003)]. This is likely due to complications in the solid state physics of the thermoluminescence process that are not incorporated into the simulation.