Organ Dose Measurement in Computed Tomography Using Thermoluminescence Dosimeter in Locally Developed Phantoms

Abstract

Introduction: Organ dose estimation using thermoluminescence dosimeter (TLD) is known to be a standard, although many other methods, such as simulation software, optically stimulated luminescent dosimeters, and photodiodes are still in use. This study aimed at directly measuring mean organ doses to the selected organs in the head/neck, chest, and abdominal regions from four computed tomography (CT) units in Lagos, south-west of Nigeria. Material and Methods: This study was conducted on locally constructed inhomogeneous phantoms to measure mean organ doses to the head/neck, chest, and abdominopelvic regions from CT units in the Lagos metropolis, Nigeria. Lithium fluoride doped with magnesium and titanium (LiF: Mg, Ti) TLD was used for the measurement. Statistical analysis was performed by IBM SPSS (version 20). Results: Validation of the designed phantoms was below ± 20% kVp and mAs parameters among the CT units, which was statistically different with regard to the observed dose discrepancies. Generally, a one-way ANOVA showed that there was a statistically significant difference in the investigated mean organ dose (P = 0.043). The comparison of the obtained results from this study with those of other studies revealed that there was no statistically significant difference in the TLDs (P > 0.05). The maximum relative difference in the dose was < 200%. Conclusion: The designed phantoms seemed to be useful for CT dose validation and could be used to validate simulation software in areas where readymade phantoms are not available.

Keywords

• Thermoluminescent-dosimeter
• Computed Tomography Phantom
• Organ
• organ dose