Comparison of entrance skin dose in the hip region in the imaging of the lower extremity by CT scan and EOS

Introduction: Increasing in refer to computed tomography (CT-scan) imaging causes to increase in cumulative dose. Stereoradiography (EOS) is an X-ray imaging technology that, by eliminating scattering radiation, reduces patient's absorption dose and improves image quality.   Materials and Methods: This cross-sectional study was carried out in a hospital with two different types of imaging apparatus, EOS Biospace Instruments and CT TOSHIBA MDCT Alexion. 15 patients were selected randomly for each Imaging method. Prior to irradiation, three thermoluminescence dosimeters (TLDs) were installed on the target area in three AP, RT and LT views. The 85 kVp and 110 kVp were used for EOS and CT respectively. The TLDs were read and the statistical analysis was performed using one-way ANOVA. Results: The mean reading of TLD dosimeters in EOS imaging of the lower regions with AP, RT and LT views were 57.88 ± 14.73, 19.84 ± 16.5 and 98.98 ± 19.59 (nc) respectively. These values with similar views in CT scan images were 1369.88 ± 585.18, 824.179 ± 35.22 and 785.66 ± 304 nc. According to the results of statistical analysis, the mean reading of TLDs in all EOS imaging views was significantly lower than the CT imaging method for estimating the entrance skin dosing. Conclusion:Stereoradiography imaging modality will impose less doses of CT scan imaging modality in similar imaging views from the lower limbs.