Effective radiation doses of patients in computed tomography of combined body areas according to phantom dosimetry

The aim of the study was to perform phantom dosimetry of organs and tissues to assess effective radiation doses to patients during computed tomography of combined areas of the body and calculated based on the readings on the scanner console.

Materials and Methods: The study was performed on СT-scanner Toshiba Aquilion 64 an anthropomorphic tissue-equivalent phantom weighing 73.5 kg using thermoluminescent detectors located in the locations of organs and tissues, under standard computed tomography protocols of two combined body regions: 1 – organs of thorax, abdomen and pelvis; 2 – organs of abdomen and pelvis. The effective radiation dose was calculated using tissue weighting factors according to NRB-99/2009 and ICRP Publication 103 recommendations.

Results and Discussion: The largest contribution to the total radiation dose was found for the gonads, red bone marrow, colon, lungs and stomach (71.8-76.2% in total). It was established that the effective radiation doses to patients during computed tomography, calculated based on the results of phantom dosimetry with TLD detectors, are higher than the values obtained from DLP data on the console of a computer scanner using tissue weighting factors according to ICRP Publication 103 for CT-1 by 1.12 times, for CT-2 by 1.13 times, according to NRB-99/2009 for CT-1 by 1.30 times, for CT-2 by 1.38 times.

Conclusion: Dosimetry on an anthropomorphic tissue-equivalent phantom demonstrates higher patient radiation doses during computed tomography compared to dose values calculated by DLP on the computed tomography scanner console. This demonstrates the importance of periodically comparing patient doses calculated by DLP on the computed tomography scanner console with doses recorded by direct dosimetry under real computed tomography scanning conditions in radiology departments and centers.

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