Improvement of the TLD dose calculation by application of an individual residual dose correction

Thermoluminescence (TL) detectors store energy from ionizing radiation, this energy is then released in the readout process by heating the detector. The light that is emitted can be recorded in the form of a glow curve (GC), from which the dose can be calculated. The TL detectors discussed in this paper are made of LiF:Mg,Ti and produced by Thermo Scientific under the name TLD-100. They are used in the routine dosimetry process of Seibersdorf Laboratories, where several thousand dosimeters need to be read every month. This paper investigates a method to improve the measurement accuracy by applying a detector-specific residual dose correction. Opposed to the current practice, where a constant value is subtracted to correct for an always present small zero-dose and a contribution from the natural background radiation, the method introduced in this paper uses a second readout immediately following the original readout to calculate and subtract a residual dose, which is then different for each detector. It will be shown that this decreases the standard deviation of detectors irradiated with the same dose, as well as allowing for a possibly smaller lower limit of detection.