ABSTRACT
Objective To quantitatively study the influence of changes in probe position on the quality control test results of dental panoramic radiography and to provide a reference for analyzing the sources of deviations in quality control test results. Methods Eight different models of dental panoramic X-ray machines were selected for this study. The film analysis method was used to determine the position of the central axis of the main beam on the image detector. The position of the probe was accurately controlled through an auxiliary moving device. The tube voltage, radiation output, and half-value layer of the useful beam were measured for positions at the center of the beam; 1 cm upward, downward, left, and right from the center of the beam; and 2 cm upward, downward, left, and right from the center of the beam. Results The tube voltage, radiation output, and half-value layer had a maximum value at the center of the beam, with a decrease in the value as the position deviated from the center. There were significant differences in the probe position sensitivity between different models of dental panoramic radiography equipment. A 2 cm deviation in the probe position resulted in an impact on the measured tube voltage of less than 5.3 kV (5.8%) for less sensitive equipment. A 2 mm deviation in the probe position resulted in an impact on the measured tube voltage of less than 5.4 kV (6.0%) for sensitive equipment. Conclusion The probe position can lead to deviation in the quality control test results of dental panoramic photography. Therefore, determining the position of the central axis of the main beam on the image detector for accurate positioning of the probe is crucial for quality control testing.