ABSTRACT
Objective To study the dosimetric characteristics of thermoluminescent dosimeter (TLD).Methods A total of 350 pieces of TLD 2000 type TLDs having the same sensitivity within ± 3.0％ were selected.The TLDs were irradiated to study the repeatability and dosage effect of TLDs by using 6 MV X-rays and 125I seeds.In order to study the dose response,the TLDs were irradiated at different dosages by using 137Cs (662 keV γ-rays),125I seeds and 6 MV X-rays.In order to study the energy response,the TLDs were exposed to the same dose,from 125I seeds,137Cs and X-rays(48,65,83,118,250 keV and 6 MV).Results The maximum deviations of the repeatability were 2.7％ and 4.0％ for 6 MV X-rays and 125I seeds,respectively,and there was no effect of dose rate observed.The dose response of TLDs to 137Cs and 125I seeds were linear.For 6 MV X-rays,the linear response was within the range of 0.74-10 Gy and non-linear range was beyond 10 Gy.The energy response to 125I seeds,48,65,83,118,250 keV and6 MV X-rays,relative to the energy response of 137Cs,were 1.70,1.25,1.08,0.99,0.91,0.96 and 1.22,respectively.Conclusions TLD 2000 has a good repeatability and linear dose response for 137Cs,125I seeds and 6 MV X-rays with no dose rate effects,but the dose response is energy dependent.
ABSTRACT
Objective To evaluate whether eight kinds of dosimeters satisfy the clinical mammography dose measurement through the comparison of energy response.Methods According to GB/T 19629-2005,the energy responses of eight available mammography dosimeters were determined for ten standard radiation qualities in the range 25-40 kVp at the SSDL using a refrence-class dosimeter.Results Except 2000S,the energy response factors of all the other dosimeters were consistent within ±5%.Conclusions The energy response of ionizing chamber type is better than other types of dosimeters.