A reject analysis of cone-beam CTs in under-aged patients

The main objective of this study was to perform a retrospective reject analysis (or audit) of 79 cone-beam CTs (CBCTs) taken in under-aged patients at the Ghent University hospital over a 2-year timespan.

Observer agreement between two oral radiologists and two senior year Master students in Paediatric Dentistry was performed for quality, diagnostic and therapeutic value. The senior year Master Students followed appropriate modules of an online course. Descriptive and comparative statistics were performed.

For the oral radiologists, all intra rater reliabilities were moderate to good (Gwet's AC1 = 0.41-0.75). For the senior students in Paediatric dentistry, these varied highly from fair to very good (Gwet's AC1 = 0.28-0.95). There was a high level of disagreement between oral radiologists and students (Gwet's AC1 = 0.16-0.45) and in-between students concerning observed quality (Gwet's AC1 = 0.29). A total of 16 CBCTs (20%) was rejected, 24 images (30%) were acceptable and 39 images (50%) had an excellent quality. 50 CBCTs were perceived to have a diagnostic advantage. 13 of the images would have no influence on the therapy, according to the oral radiologists. A significant correlation was found between unacceptable quality, absence of perceived diagnostic advantage (p = 0.004, RR = 2.4) and influence on therapy (p < 0.0005, RR = 1.8). A small field of view (FOV) was positively correlated to an excellent quality of the image (p = 0.011, RR = 2.8).

Image quality did not reach the proposed boundary of 10% according to the European Guidelines on Radiation Protection in Dental Radiology. This is the first published audit on an overall database of under-age children for CBCT.