Retrospective dosimetric analysis and establishment of local typical dose values for otolaryngology scans performed...

To analyze dosimetric data and establish local typical dose values (LTDVs) for otolaryngology scans performed on cone-beam CT (CBCT) MATERIALS AND METHODS: Dosimetric indicators were retrospectively collected for otorhinolaryngology examinations performed on a CBCT device. LTDVs were determined for each examination type using weighted computed tomography air kerma index (C_w), air kerma-length product (P_KL), kerma-area product (P_KA) and acquisition length. C_w, P_KL and length were compared according to the acquisition protocols. CBCT LTDVs were compared with those obtained using multi-slice CT (MSCT) for inner ear and sinus examinations.

Inner ear examinations showed significantly higher C_w, P_KL and P_KA values than other examination types, with mean increases of 206.7 ± 15.8%, 29.0 ± 3.7% and 17.0 ± 2.3%, respectively (p < 0.001 and 0.50 ≤ ES ≤ 0.87). Salivary gland and sinus examinations showed similar values (0.503 ≤ p ≤ 0.749), while facial massif examinations showed significantly lower values -8.4 ± 0.0%, -4.8 ± 0.0% and -3.2 ± 0.6%, respectively (p < 0.041 and ES ≤ 0.20). The C_w decreased as the FOV increased and the opposite was found for P_KL and acquisition length. CBCT's LTDVs were lower than with MSCT for the inner ear by 43.9 ± 1.7%. For sinuses, CBCT's LTDVs were 30% lower than the national diagnostic reference levels (NDRL) for C_w and 39.5% lower for P_KL but 43.3 ± 1.9% higher than the LTDVs for MSCT.

In CBCT-based ENT imaging, inner ear examinations involve the highest radiation doses, although these remain lower than with MSCT. Sinus doses are lower than MSCT NDRLs but higher than LTDVs.