Diagnostic capability and radiation dose of cone beam CT dacryocystography in different scanning fields of view in healthy volunteers

Objectives Cone beam CT dacryocystography (CBCT-DCG) is a new imaging technique for assessing the lacrimal drainage system (LDS). The purpose of this pilot study is to compare the diagnostic capability and radiation dose of CBCT-DCG in different scanning fields of view (FOV) to evaluate the possibilities of the reduction of radiation dose. Methods Fifteen healthy volunteers underwent CBCT-DCG in an upright position. The first five subjects were scanned using the scanning FOV of 11 × 10 cm (Group A), then 8 × 8 cm (Group B), and the last five subjects 5 × 5.5 cm (Group C). The image quality and diagnostic validity of different groups were evaluated by two experienced otolaryngologists. The effective dose of each group was calculated and compared. Results All images showed good delineation of the LDS and its surrounding structures. With regard to the image quality and diagnostic validity, no differences were found among different groups. Compared with Group A, the effective radiation dose for Group B (38.40 μSv) was 38.54% lower and that for Group C (17.12 μSv) was 72.60% lower. Conclusions A substantial reduction of the effective dose for CBCT-DCG in healthy volunteer by decreasing FOV is possible without compromising the diagnostic capability. CBCT-DCG is a potential valid first-line imaging test for the evaluation of LDS, and it permits functional assessment of lacrimal drainage.