MEASUREMENT OF ENTRANCE SURFACE DOSE WITH THE FEMALE ANTHROPOMORPHIC PHANTOM ON SELECTED DIAGNOSTIC EXAMINATION USING THERMOLUMINESCENCE DOSIMETRY

ABSTRACT The aim of the study was to measure the entrance surface dose for selected diagnostic Xray examinations using calibrated thermoluminescent dosimeters on an anthropomorphic phantom. Dose measurement obtained with PCXMC software calculations were used to estimate the stochastic radiation risks and age-dependent mortality rates for subsequent assessment of lifetime cancer risk. Entrance surface dose per examination was estimated from X-ray tube output parameters in two digital X-ray units and a sample of 384 exposures were made. Exposed thermoluminescent dosimeters which were used in the study were read using Harshaw TLD reader Model 6600. The mean entrance surface doses in the two hospitals ranged from 0.2 – 0.3 mGy for chest posterior-anterior, 0.4 – 2.2 mGy for lumbar spine anterior-posterior, 1.1 – 2.1 mGy for lumbar spine lateral, 0.4 – 4.0 mGy for pelvis anterior-posterior, 0.5 – 0.8 mGy for skull lateral and 0.6 – 0.7 mGy for skull anteriorposterior. The risk of exposure-induced cancer deaths for chest posterior-anterior, pelvis anterior-posterior, skull and lumbar spine are 8.41E-04%, 3.90E-03%, 1.16E-04% and 7.29E-04% respectively. With the exception of chest posterior-anterior examinations, mean entrance surface dose were found to be within the National Radiological Protection Board, Commission of European Communities, International Atomic Energy Agency and United Kingdom reference doses. This work forms part of the national effort to establish National Diagnostic Reference Levels for the selected x-ray examinations.