Objectives: To assess patient movement characteristics in children and young adults and the impact on CBCT image quality.
Methods: During 33 CBCT examinations, the patients (age: average, 14 years; range, 9-25 years) who had moved were identified by video observation [movement group (MG)]. The CBCT data sets were matched with those of 33 non-moving patients according to age, diagnostic task, examined region, field of view and voxel resolution [non-movement group (N-MG)]. Three observers scored the videos of MG, regarding motional state second by second (moving/non-moving), and movement characteristics: duration (in seconds), complexity (uniplanar or multiplanar) and distance (<3/≥3 ≤ 10/>10 mm). The observers blindly assessed axial sections of the 66 examinations individually, categorizing the image quality (appropriate/acceptable/inappropriate). Next, the observers blindly assessed axial sections of the matched-pairs images simultaneously, deciding which image in the pair had the highest image quality or if it was impossible to decide. The relationship between image quality and movement/movement characteristics was evaluated.
Results: When the 66 CBCT images were evaluated individually, no relationship between image quality and movement was found. However, based on the matched-pairs assessment, accumulated number (≤2 vs ≥3, p = 0.039), duration (≤5 s vs ≥6 s, p = 0.024) and complexity (uniplanar vs multiplanar, p = 0.046) of movements had an impact on image quality; the more severe the movement, the more often the image quality was assessed lower in the MG.
Conclusions: Axial CBCT images of young patients who moved during examination did not always present lower quality than images originating from non-moving patients. Image quality was, however, significantly lower in the moving patients when movement occurred several times, had a long duration or was multiplanar.
Keywords: cone beam CT; image quality; motion artefacts; patient movement.