Towards Image Quality Analysis of Small and Full Field of View Dental Cone Beam CT Systems

Cone-beam CT (CBCT) systems have been used for dentomaxillofacial surgery applications. Different dental CBCT devices are being developed and released, with a wide variability of exposure parameters and fields of view. Although they have sufficient diagnostic quality, a quantitative analysis of image quality and radiation dose is required to enable their optimal use. The aim of this study was to develop and implement a feasible methodology for image quality analysis for different dental CBCT devices. The methodology was based on conventional CT quality control procedures and adapted to overcome the limitations of dental CBCT. A prototype phantom was specially designed to allow the acquisition of image quality parameters relevant to dental imaging. Equipments were divided into categories, related to their field of view: Small Field of View (SFOV) and Full Field of View (FFOV). The following image quality parameters were evaluated: uniformity, noise, contrast-to-noise ratio, CT number accuracy, artifacts, spatial resolution and geometric distortion. Applicability of the methodology was assessed using one SFOV and four FFOV CBCT devices. Results from preliminary analyses of the prototype phantom showed its potential for routine quality assurance on dental CBCT. Large differences in image quality performance were seen between the devices.