Radiation dose measurements in a dental orthopantogram unit using indigenously developed optically stimulated luminescence dosimeters

Dental orthopantogram (OPG)/cone beam computed tomography (CBCT) scanners are gaining popularity due to their 3D imaging with multiplanar view that provides clinical benefits over conventional dental radiography systems. Dental OPG/CBCT provides optimal visualization of adjacent overlaying anatomical structures that will be superpositioned in any single projection. The characteristics of indigenously developed optically stimulated luminescence dosimeters, namely, aluminium oxide doped with carbon (Al₂ O₃ :C), lithium magnesium phosphate doped with terbium and boron (LiMgPO₄ :Tb,B) and lithium calcium aluminium fluoride doped with europium and yttrium (LiCaAlF₆ :Eu,Y) were evaluated for their use in dental dosimetry. The dose-response of these dosimeters was studied at X-ray energies 60 kV, 70 kV and 81 kV. Radiation doses were also measured using Gafchromic film for comparison. Radiation dose was measured at eight different locations of a polymethyl methacrylate (PMMA) head phantom including eyes. The optically stimulated luminescence (OSL) sensitivity of LiMgPO₄ :Tb,B is about 1.5 times and LiCaAlF₆ :Eu, is about 20 times higher than the sensitivity of Al₂ O₃ :C. It was found that measured radiation doses by the three optically stimulated luminescence dosimeters (OSLDs) and Gafchromic film in the occipital region (back side) of a PMMA phantom, were consistent but variations in dose at other locations were significantly higher. The three OSLDs used in this study were found to be suitable for radiation dose measurement in dental units.