Document Type : Original Paper
Malekashtar University,Tehran, Iran
Medical Physics Dept, Faculty of Medicine, Mashhad University of Medical Sciences
Medical Physics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
Energy Engeineering and physics faculty, Amirkabir University of Technology, Tehran, Iran
Medical Physics Department, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
Introduction: LiF dosimeter has the most application in medicine. This study aimed to evaluate some dosimetric properties of a novel LiF: Mg, Ti.
Materials and Methods: An ELEKTA Precise linear accelerator was used to calibrate dosimeters at 6 MV. In this survey, responses of dosimeters were evaluated up to 1000 cGy. Background effect was investigated in two different dosimeter states including irradiated and unirradiated.Thermoluminescence response dependence to dose rate was investigated, as well. Energy dependence was evaluated in diagnostic and therapeutic ranges. Furthermore, fading effect was evaluated by reading the dosimeters every 2 h up to 12 h post-irradiation.
Results: The dosimeters had linear response up to 250 cGy. Readout values of dosimeters receiving 120 cGy at three dose rates of 21, 212, 425 cGy.min-1 were calculated equal to 125, 123, 121 cGy, respectively. The measured values of delivering 80, 120, and 150 cGy prescribed doses at 6 MV, 10 MV, and 15 MV were accurate at 6 MV and about 1.5 times higher than the prescribed doses at 10 and 15 MV. Thermoluminescence response in diagnostic energy range showed an uprising trend with increasing energy.
Conclusion: The raising thermoluminescence response with increasing energy contradicts with the findings of Nunn. Due to the reproducibility and linear response of dosimeters in an acceptable dose range, they could be used in diagnostic and therapeutic fields. Effects of absorbed doses from background in low-dose studies, mainly in diagnostic radiology range, could be evaluated in more detail in future surveys.