Premium
SU‐GG‐T‐241: Determination of the Energy Correction Factor for TLD‐100 in 6 and 10 MV Photon Beams Relative to 60Co
Author(s) -
Junell S,
DeWerd L
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 - 10.1118/1.2961993
Subject(s) - thermoluminescent dosimeter , linear particle accelerator , dosimeter , nuclear medicine , ionization chamber , thermoluminescence , photon energy , dosimetry , irradiation , photon , materials science , physics , beam (structure) , optics , nuclear physics , ion , medicine , quantum mechanics , ionization
Purpose: To determine the energy correction factor for TLD‐100 chips comparing 6 MV and 10 MV photon beams produced by a Varian Linac to60 Co energy. Method and Materials: The energy correction for the difference in thermoluminescent (TL) response for 6 and 10 MV photons from a linac compared to60 Co energies were measured with LiF TLD‐100 (LiF:Mg, Ti) thermoluminescent dosimeters (TLDs). This energy correction and dose dependence were determined by irradiating TLD‐100 chips (3 mm × 3 mm × 1mm) to varying doses (100–300 cGy) using60 Co and 6 and 10 MV photons from a Varian linac. TLD irradiations were done in liquid water with water tight Virtual Water™ TLD holders. Doses delivered to the TLDs for both60 Co and linac irradiations were verified with ion chamber measurements following the AAPM's TG‐51 protocol.60 Co TLD irradiations were also done in air with a PMMA holder. Monte Carlo methods were used to determine the absorbed dose to water at the same location where the TLDs were irradiated. Results: The energy correction factor was determined to be the ratio of linac TL output to the dose delivered by the linac divided by the60 Co TL output. The results of the test showed less than a two percent correction for both the 6 and 10 MV beam with standard deviation of the mean of less than 0.2 percent. No dose dependence was seen in the range of 100 to 300 cGy. Conclusion: The energy correction factor for TLDs allows TLDs to be used as a secondary verification of linac outputs relative to a60 Co standard.