Abstract

Background and aim: Computed Tomography (CT) is a key tool in medical diagnostics but is associated with significant ionizing radiation exposure, highlighting the need to optimize doses through Diagnostic Reference Levels (DRLs). The current study aimed to assess CT radiation dose and propose a National Diagnostic Reference Level (NDRL) for the 5 most frequent adult studies using CT dose parameters such as CT Dose Index Volume (CTDIvol) and Dose Length Product (DLP) as well as to compare the practices for aforementioned examinations between hospitals in Costa Rica's public sector. Materials and methods: Data from patients and studies developed in 11/12 public hospitals in Costa Rica between January to August 2024 were collected. Procedures performed on adults for five main anatomical regions (head, cervical spine, chest, abdomen-pelvis, and chest-abdomen-pelvis) were analysed, using the 50th and 75th percentiles of dosimetric parameters (CTDIvol and DLP) as reference exposure values. The NDRL was achieved from the third quartile of median CTDIvol and DLP for each hospital and examination. Results: The proposed public National Diagnostic Reference Levels (NDRLs) are as follows: for Head examinations, a CTDIvol of 52 mGy and a DLP of 1239 mGy cm; for Cervical Spine, 22 mGy and 774 mGy cm; for Chest, 10 mGy and 594 mGy cm; for combined Abdomen-Pelvis studies, 14 mGy and 1283 mGy cm; and for combined Chest-Abdomen-Pelvis studies, 12 mGy and 1498 mGy cm. Overall, these values align with international reference levels in terms of CTDIvol; however, notable discrepancies were observed in DLP values-particularly for Chest-Abdomen-Pelvis exams, where the proposed level exceeded the French NDRL by up to 170 %. Conclusion: While the NDRLs outlined in this study were generally acceptable and consistent with previously published research, optimizing radiation doses remains imperative, particularly for those equipment and hospitals with values above the reference. This analysis represents the first effort to establish DRLs in Costa Rica, providing a robust foundation for optimizing radiological safety.