National diagnostic reference levels based on clinical indications and patient size for adults’ computed tomography in the Kingdom of Bahrain

The study aims to establish national diagnostic reference levels (NDRLs) for computed tomography (CT) examinations performed on adult patients based on clinical indications, patient gender, and size in the Kingdom of Bahrain. The volume CT dose index (CTDIvol) and dose length product (DLP) were collected between September 2020 and September 2021 from 63% of the total number of CT scanners in the country (five out of eight CT scanners). The data were collected from at least ten patients for eight common clinical indications in the head, abdomen-pelvis and chest-abdomen-pelvis (CAP) regions. The NDRLs were calculated for each clinical indication as the third quartile of the CT scanners' median values of CTDIvol and DLP. They were also calculated based on the patient's gender (for the head) and their size (for the abdomen-pelvis and CAP clinical indications). From 1665 CT examinations, the NDRLs in term of CTDIvol were 67, 66, 67, 13, 14, 17, 19, and 15 mGy for symptoms of headache, trauma, stroke, flank pain, renal colic, abdominal pain, diverticulitis/appendicitis and oncologic follow-up, respectively. Likewise, these were 1206, 1286, 1152, 690, 779, 972, 1061, 1073 mGy cm in terms of DLP, respectively. For large size patients, NDRLs in terms of CTDIvol were on average 1.7 times higher than those from medium size patients for all the clinical indications in the abdomen-pelvis and CAP regions. The NDRLs were established for the most common clinical indications in the Kingdom of Bahrain. They are higher than those established in the literature, thus emphasizing the urgent need of an optimization strategy for better patient radiation protection. •National diagnostic reference levels (NDRL) are established for eight common clinical indications for adults CT in Bahrain.•Bahraini NDRLs are higher than those established in the literature for the most clinical indications.•For trunk clinical indications, NDRLs for large patients are on average 1.7 times higher than medium size patients.