Patient movement during extraoral radiographic scanning

Objectives: To assess directional patient movement during extraoral scans. Methods: Ten reference points (RPs) were marked on the faces of 20 patients. Frontal and lateral digital photographs were obtained continuously during panoramic scanning. The largest overall distances between the same RPs (and their corresponding horizontal and vertical vectors) were measured for the following time frames: 0–15 s, 0–25 s, and 0–40 s. Movements were compared between frontal and lateral photographs and between time frames by the Wilcoxon matched-pairs test and Mann–Whitney U test, respectively. Results: The mean maximal overall patient movement was 1.44 ± 0.93 mm (range 0.6–4.5 mm) for frontal photographs and 1.89 ± 1.35 mm (range 0.8–5.8 mm) for lateral photographs. The movements in the lateral photographs were significantly greater than those in the frontal photographs (p < 0.001). The magnitudes of the movements were larger for the longer time frames. Conclusions: Sizable patient movement during scanning was observed. These movements increased with time. This potential source for error should be considered when attempting to improve the accuracy of scanning devices.