Document Type : Original Paper
Medical Physics Department, Medical Physics Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
Medical Physics Research Centre, Mashhad University of Medical Sciences, Mashhad, Iran
Student Research Committee, Mashhad University of Medical Sciences, Mashhad, Iran - Department of Medical Physics, Faculty of Medicine, University of Medical Sciences, Mashhad, Iran
Introduction: In radiation therapy, knowing the dose rates to healthy organs and tumors is beneficial, and thermoluminescent dosimeter (TLD) allows for this possibility. This study was aimed at determining the dose-response differences of TLDs in various types of radiation, energy levels, and dose rate calibrated with other types of radiation beams and energy and dose levels.
Materials and Methods: In this study, LiF:Mg,Ti (TLD-100) was used for dosimetry. Photon and electron irradiation was performed by Elekta Precise Linear Accelerator. First, TLDs were calibrated in three different groups of 6 MV photon, 6 MeV electron, and 60Co teletherapy photon beam with 50 cGy dose. Next, each group was irradiated with 6 MV photon, 6 MeV electron, and 60Co teletherapy photon beam separately at three different dose levels of 20, 60, and 100 cGy.
Results: TLDs calibrated with electron were significantly different at all dose levels and with all types of radiation from TLDs calibrated with photon or 60Co teletherapy photon beam (P=0.000). P-value of the TLDs calibrated with 6 MV photon versus 60Co was less than 0.94. The maximum standard deviation belonged to 100 cGy irradiation, while the least pertained to 20 cGy irradiation.
Conclusion: Calibration of TLDs depends on the type of radiation.