Response of new TLDs to medium and low energy X-rays

In order to determine the energy response characteristics, several types of TLDs previously calibrated with 137Cs gamma rays, were irradiated with X-ray beams in the range of effective energies between 33 and 116 keV. The following types of TLDs were investigated: two types of the recently developed highly sensitive LiF:Mg,Cu,P material: TLD-700H and GR 200A, two new types on the basis of lithium borate: Li2B4O7:Cu,In and Li2B4O7:Cu,In,Ag (developed in the Institute of Nuclear Science, Vinča), two well known types of LiF:Mg,Ti detectors: TLD-100 and TLD-700 and the new, highly sensitive Al2O3:C. Measured energy responses relative to air, normalised to 137Cs photons were compared with calculated data. Although the deviations of the measured data from the “theoretical” predictions are different for all investigated TLDs, there are no large differences in “tissue equivalency” between them. The only exception is Al2O3:C, which (due to large energy dependence) is not suitable for personal dosimetry in an unknown photon radiation field.