Comparison of the Measurement Uncertainty of Thermoluminescence Dosimeters (TLD-100 and GR- 200) in Clinical Radiotherapy Energies

Background: Accurate determination of individual radiation doses is critical in dosimetry, and international standards emphasize the importance of reporting measurement uncertainties. Neglecting measurement uncertainty undermines the reliability of reported dosimetric values, as emphasized by international standards. Objective: This study aimed to evaluate the measurement of uncertainties in two Thermoluminescent Dosimeters (TLDs)-100 and GR-200, in the dose range of 30–150 cGy. Material and Methods: In this experimental study, we evaluated the measurement of uncertainties in two thermoluminescent dosimeters, TLD-100 and GR-200, in the dose range of 30–150 cGy. The study investigated both random (Type A) and systematic (Type B) uncertainties. Random uncertainties include the non-uniformity of dosimeter sensitivity Element Correction Coefficient (ECC), variability in dosimeter response at zero dose, and repeatability. Systematic uncertainties include the dependence of dosimeter response on radiation energy, radiation angle, nonlinearity of dosimeter response, fading, ambient light effects, and reference calibration errors. Results: The total uncertainty for TLD-100 was calculated as 10.99% at a 68% confidence level (21.99% at 95% confidence), while for GR-200, it was 13.63% at a 68% confidence level (27.26% at 95% confidence). These values are well below the 42% threshold recommended by the International Atomic Energy Agency (IAEA) for personal dosimetry services. Conclusion: The GR-200 exhibits higher sensitivity for low-dose radiation detection; however, its greater uncertainty makes TLD-100 more suitable for clinical and personal dosimetry applications, where precision and reliability are paramount.