Evaluation of Dose Distribution Homogeneity and Accuracy for a Cs-137 Source Using Thermoluminescent Dosimeters (CaSO4:Dy and LiF:Mg,Ti)

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Yuni Warty, Dewi Wulandari, Soraya, Abdul Rahim, Abdon Manalu

2026 Iranian Journal of Medical Physics Vol. 23 Issue 1 Article Cited by 0

Abstract

Introduction: Cesium-137 (Cs-137) is a widely used source of ionizing radiation across various fields.Thermoluminescent dosimeters (TLDs), due to their sensitivity and reliability, are frequently employed to measure radiation dose in medical, industrial, and research applications. This study specifically aims to assess the homogeneity and accuracy of CaSO4:Dy and LiF:Mg,Ti TLDs to support calibration and radiation safety practices. Material and Methods: The experiment utilized the G-10-360-15CS Gamma Beam Irradiator as the radiation source. The CaSO4:Dy and LiF:Mg,Ti TLDs were mounted on a 30 × 30 × 5 cm Polymethyl Methacrylate (PMMA) phantom. The testing procedure included TLD annealing, homogeneity testing, and dose accuracy assessment. The TLDs were calibrated using a Cs-137 reference source by comparing the actual delivered dose to the TLD readings. Testing was conducted at doses of (0.1 mSv and 0.5 mSv) and distances (100, 150, and 200 cm). Results: The homogeneity test showed a uniform dose distribution (CV ≤ 15%) at distances of 150 cm and 200 cm. The accuracy test indicated a performance bias of –9.21% to –2.50% for TLD CaSO4:Dy, with calibration factors ranging from 1.026 to 1.101, and a performance bias of 2.46% to –0.28% for TLD LiF:Mg,Ti, with calibration factors of 0.976 to 1.003. All values meet the required tolerance limits. Therefore, TLD CaSO4:Dy and TLD LiF:Mg,Ti are suitable for radiation dose measurements. Conclusion: Homogeneity and accuracy testing of TLD CaSO4:Dy and LiF:Mg,Ti shows that dose distribution becomes more homogeneous as the distance increases. The best measurement accuracy is achieved at shorter distances. © 2026 Mashhad University of Medical Sciences. All rights reserved.

Affiliations

Department of Physics, Faculty of Mathematics and Natural Sciences, State University of Medan, Indonesia; Radiation Measuring Instruments Laboratory, Center for Safety of Health Devices and Facilities (BPAFK) Medan, Ministry of Health, Indonesia