Abstract:

Objective
To compare the actual dose of patients who receive the same medical practice by either digital panoramic X-ray unit and general panoramic X-ray unit and give evidence for better selection of oral X-ray examination method.Methods Round sheet lithium fluoride(LiF)  thermoluminescent dosimeters(TLD) were used.The experiment was divided into natural background contrast group,general panoramic X-ray children group,general panoramic X-ray adults group,digital panoramic X-ray children group and digital panoramic X-ray adults group.The dosimeter of natural background radiation was placed at the office of the doctor,the dosimeters of  general panoramic X-ray children group and  general panoramic X-ray adults group were irradiated by different conditions according to the clinical application of panoramic X-ray to children and adults,the dosimeters of digital panoramic X-ray children group and digital panoramic X-ray adults group were irradiated by different conditions according to the clinical application of digital panoramic X-ray to children and adults.The thermoluminescent dosimeter was used to count and calculate the exposure doses in various groups.Results The dose of children exposed in general panoramic X-ray unit was 1.28 times of that in digital panoramic X-ray unit,there was significant difference（t=6.904,P<0.01）.The dose of adults exposed in general panoramic X-ray unit was 1.55 times of that in the digital panoramic X-ray unit,there also was significant difference（t=－11.514.P<0.01）.Conclusion The digital panoramic X-ray unit can reduce the dose of patients,so the digital panoramic X-ray unit should be used as far as possible.