Scan factors and practices associated with radiation doses for chest CT: current Brazilian scenario

The main purpose of this study was to compare the parameters of computed tomography (CT) and the corresponding patient doses undergoing chest CT scan examinations in different regions of Brazil, providing the current scenario of how these procedures are being carried out in the country as well as the patient dose distribution. Thirty institutions, across 17 states and the Federal District, participated in the survey. The evaluation included 30 multislice CTs of seven different models, manufactured by General Electric (GE) Healthcare. For each institution, data from 10 adult chest CT examinations, performed without contrast, were collected remotely. The analysis of the results showed a significant difference of the CTDI_volvalues, ranging from 1.1 mGy to 46.6 mGy in seven institutions. The mean value of CTDI_volwas higher than values found in the literature and the UK Reference Levels. It was also observed that, regardless of the region of the country, for the same CT model, different scanning parameters were used, which resulted in CTDI_volup to 5 times higher in some institutions. Repetitions of CT acquisitions and scouts with radiation field dimensions larger than the region of interest were found in 25% of chest examinations, resulting in higher absorbed doses. The results of this work show a mapping of the chest CT procedures, which enables the establishment of strategic plans for the country. In addition, each institution will be able to implement an appropriate optimization program and establish institutional reference levels.