A comparative study of the effective radiation doses from cone beam computed tomography and plain radiography for sialography.

Objectives: As a first step in developing a protocol for multidimensional sialography using cone beam CT (CBCT), the objective of this study was to compare the effective radiation doses from sialography of the parotid and submandibular glands using plain radiography and CBCT. Methods: The effective doses were calculated from dose measurements made at 25 selected locations in the head and neck of a radiation analogue dosimeter (RANDO) phantom, using International Commission on Radiological Protection 2007 tissue weighting factors. Results: The effective dose (E) changed in relationship to changes in CBCT field of view (FOV), peak kilovoltage (kVp) and milliamperage (mA). Specifically, E decreased from a maximum of 932 mu Sv (30 cm FOV, 120 kVp, 15 mA) to 60 mu Sv (15 cm FOV, 80 kVp, 10 mA) for a parotid gland study and to 148 mu Sv (15 cm FOV, 80 kVp, 10 mA) for a submandibular study. The collective series of plain radiographs made during sialography of the parotid and submandibular glands yielded effective doses of 65 mu Sv and 156 mu Sv, respectively. The plain parotid gland series included one panoramic, two anterior-posterior skull and four lateral skull radiographs, whereas the submandibular gland series included one panoramic, one standard mandibular occlusal and four lateral skull radiographs. Conclusion: The effective doses from CBCT examinations centred on the parotid and submandibular glands were similar to those calculated for plain radiograph sialography when a 15 cm FOV was chosen in combination with exposure conditions of 80 kVp and 10 mA. Dentomaxillofacial Radiology (2010) 39, 257-263. doi: 10.1259/dmfr/62878962