OA080] Assessment of exposure and setting of local diagnostic reference levels for CT procedures

Abstract

Purpose According to international and national guidelines, European Directive, countries should establish diagnostic reference levels (DRL) in order to manage optimal radiation dose for patients. One of the tools is to periodically reassess patient doses and local values of the DRL in healthcare institutions. The aim of this study was to perform the assessment of paediatric and adult patient exposure doses and establish the local DRL values for most common CT procedures. Methods The data used in this study were collected from 3 CT scanners and included 4600 CT diagnostic procedures. Patient-related and exposure-related parameters were collected. The median DLP values and effective doses were estimated for head and chest scans in different patient age groups. Local DRLs were calculated using the 75th percentile and comparison with and national DRLs and European guidelines are done. Results The patient exposure assessment studies were started at 2010 and after the analysis of the results the number of corrective actions, including optimised examination protocols, were performed. Dose decreased in all age groups from 2010 to 2017, up to 3 times in youngest patients. In 2017, the median DLP for head was 156, 287, 274, 300 and 351 mGy*cm for patients aged 0–1, 1–5, 5–10, 10–15 and 15–18 years respectively. The mean DLP for chest was 46, 48, 100 and 194 mGy*cm for patients aged 1–5, 5–10, 10–15 and 15–18 years, respectively. For adults, head and chest CT median DLP values were 732 mGy*cm and 578 mGy*cm respectively. The median values for specific CT procedures of cardiac and brain perfusion were 318 mGy*cm and 4990 mGy*cm, which are not set by National DRLs, but are proposed to be set as local DRLs for further evaluation. Conclusion Patient doses showed a wide variation due to patient clinical indication, CT system equipment and image acquisition parameters. The patient doses were slightly lower than the national DRLs and in comparison with other healthcare institutions, the average doses were at the similar level. Local DRLs were set for head and chest CT procedures for paediatric and adult patients.