Linear accuracy of cone-beam computed tomography and a 3-dimensional facial scanning system: An anthropomorphic phantom study

Abstract

PurposeThis study was conducted to evaluate the accuracy of linear measurements of 3-dimensional (3D) images generated by cone-beam computed tomography (CBCT) and facial scanning systems, and to assess the effect of scanning parameters, such as CBCT exposure settings, on image quality.Materials and MethodsCBCT and facial scanning images of an anthropomorphic phantom showing 13 soft-tissue anatomical landmarks were used in the study. The distances between the anatomical landmarks on the phantom were measured to obtain a reference for evaluating the accuracy of the 3D facial soft-tissue images. The distances between the 3D image landmarks were measured using a 3D distance measurement tool. The effect of scanning parameters on CBCT image quality was evaluated by visually comparing images acquired under different exposure conditions, but at a constant threshold.ResultsComparison of the repeated direct phantom and image-based measurements revealed good reproducibility. There were no significant differences between the direct phantom and image-based measurements of the CBCT surface volume-rendered images. Five of the 15 measurements of the 3D facial scans were found to be significantly different from their corresponding direct phantom measurements (P<.05). The quality of the CBCT surface volume-rendered images acquired at a constant threshold varied across different exposure conditions.ConclusionThese results proved that existing 3D imaging techniques were satisfactorily accurate for clinical applications, and that optimizing the variables that affected image quality, such as the exposure parameters, was critical for image acquisition.

Soft tissue compensation evaluation in patients with facial asymmetry using cone-beam computed tomography combined with 3D facial photographs

“…Additionally, the high-resolution images in color and texture at a relatively fast speed are the main reasons for its popularity [ 13 , 14 ]. Even though this method has had some distortions in overlapping areas and has failed to accurately represent the submental area, several investigations revealed that the Morpheus 3D® scanner was sufficiently accurate for clinical application, diagnosis, and attaining satisfactory treatment outcomes [ 13 , 15 ]. Few studies have reported the high accuracy and consistency of this method, and the discrepancy in the interalar width between direct measurement and 3D facial photography was less than 0.2 mm [ 13 , 15 , 33 ].…”

“…In addition, a recent method to overcome these limitations is 3D photogrammetry via facial scanners, such as the Morpheus 3D® scanner, which has important benefits: the image from the 3D facial scan is captured at an angle and distance that are independent and measurable, and an analysis in three planes of the axis can be adjusted by users. Thus, the soft-tissue image from a 3D facial scan is widely used in combination with the hard-tissue image from CBCT to evaluate the relationship between the soft and hard tissue and achieve a definitive diagnosis of facial asymmetry [ [13] , [14] , [15] ]. However, the hard- and soft-tissue relationships are not always harmonious.…”

Accuracy of facial skeletal surfaces segmented from CT and CBCT radiographs

“…The image quality, and thus, the diagnostic value of a 3D radiograph can greatly vary depending on the radiographic machine, the image acquisition parameters (voxel size, kV, mA), the field of view (FOV) and the complexity or consistency of the scanned object, especially in CBCT images 2 , 5 , 6 . CBCT is the most common 3D radiographic examination in dentistry and offers generally reduced radiation exposure and faster acquisition time than a conventional CT scan, at the expense of image quality 7 .…”