Ionizing radiation and its considerations in imaging diagnosis: comparison of absorbed dose between cone beam computed tomography and multi-detector computed tomography in the head and neck

Abstract

Introduction: The objective of this study was to compare the mean absorbed dose in patients undergoing head and neck examinations using two cone beam computed tomography (CBCT, Kodak and i-CAT) and one multi-detector computed tomography (MDCT). Methods: Three thermoluminescent dosimeters (TLDs), calibrated in air kerma, were positioned in 24 regions of the head and neck of a phantom simulating an average adult. The mean absorbed dose (mGy) values in these positions, for different organs and tissues, were obtained using correction factors, considering the ratio between the mass energy absorption coefficients of organ/tissue and air. Comparison between radiation doses in the most radiosensitive regions was done by calculating the ratio of these dose values, with propagated uncertainty. Results: The dose in all regions was significantly higher for MDCT when compared to CBCT. Concerning CBCT equipment, the Kodak device had a higher absorbed dose than the i-CAT for most of the regions tested. The uncertainty of the i-CAT was greater than that of the Kodak. Conclusion: Due to the considerable difference between absorbed doses, emphasizing the higher dose values obtained in MDCT, the dissemination of CBCT application in medicine is recommended, as well as further studies to broaden the criteria for use.