Potential of dosage reduction of cone-beam CT dacryocystography in healthy volunteers by decreasing tube current

Cone-beam CT dacryocystography (CBCT-DCG) is a newly developed lacrimal passage imaging technique. This pilot study aimed to determine the effect of reducing tube current on image quality and radiation dose of CBCT-DCG in healthy volunteers. Thirty volunteers were randomly divided into three groups of ten. Each group of subjects underwent CBCT-DCG using a tube current of 13 mA, 10 mA, and 7 mA respectively. The image quality of CBCT-DCG was assessed independently by two observers using three different scoring methods and compared among the groups. The effective dose was estimated and compared among the three different tube current groups. The CBCT-DCG images provided a high spatial and contrast resolution of the bony structures and the contrast medium. No significant differences were found in the image quality between different tube current groups. Compared with the 13 mA group (49.44 μSv), the effective dose for 10 mA group (38.40 μSv) and 7 mA group (27.12 μSv) decreased by 22.33% and 45.15%, respectively. By decreasing the tube current, CBCT-DCG can be performed with a significant reduction of effective dose without loss of image quality in healthy volunteers. (author)