In vivo measurements in pediatric computed tomography with TLD: A correlation between CDTIvol values

Abstract

This study investigates pediatric Computed Tomography (CT) dosimetry, specifically in the thoracic and head regions, using thermoluminescent dosimeters (TLD). The investigation, conducted at the Imaging Diagnostic Center of the Dom Vicente Scherer Hospital, involved two CT machines, the GE Optima 540 and Revolution EVO models. It aims to correlate in vivo TLD analysis with experimental CT Dose Index Volume (CTDIvol) values. The research reveals a maximum variation between machine-indicated CTDI values of 5.7% for the Optima 540 model and 6.8% for the Revolution EVO model at a voltage of 120 kV. Comparison with dose reference levels (DRL) from the United Kingdom and the United States indicates that the obtained values are below these standards, suggesting safe practices in the participating hospital. However, a larger sample size is recommended to establish local standards securely. In the thoracic region, nominal CTDI_vol values indicate measurements around 150% lower than the dose values measured by TLD's, however, no correlation was found between the two variables (p-value = 0.09). In the head, nominal CTDI_vol values varied on average 21% above the doses measured by TDL's, showing a strong correlation between the two quantities (p-value = 0.0002). The study highlights the importance of cautious interpretation of the CTDI_vol and the need for continuous optimization of procedures to ensure safe practices and minimize the risks of radiation exposure in pediatric patients.