上气道DR管电压与辐射剂量和图像质量的关系

The relationship of radiation dose and image quality with tube voltage selection for adult upper airway radiography

目的探讨成人上气道DR管电压选择与辐射剂量和图像质量的关系。方法用聚甲基丙烯酸甲酯（PMMA）模拟成人上气道厚度和对比度细节体模（CDRAD2．0）组合，以不同管电压自动曝光控制系统（AEC）摄影，记录入射体表剂量（ESD）、剂量面积乘积（DAP）和曝光量（mAs），计算体模图像质量因子（IQF值），选定适宜管电压。结果ESD、DAP、mAs随着管电压升高而下降，IQF值却增大，其间差异有统计学意义（g=45．15、26．41、29．26、56．53，P〈0．05）。75kV以下ESD、DAP、mAs明显增大，75kV以上逐渐降低，75～80kV趋于平衡。50～75kV之间IQF值差异无统计学意义，75—90kV之间IQF值差异有统计学意义（F=11．35，P〈0．05）。不同管电压的正常人体上气道的图像质量无明显差异。结论成人上气道DR的适宜管电压范围为75～80kV，用IQF值对照图像质量评分可为临床评价图像质量提供依据。

Objective To investigate the relationship between the tube voltage and radiation dose as well as image quality in adult upper airway digital radiography （DR）. Methods We used CDRAD2.0 contrast details phantom and PMMA to simulate adult upper airway. With different tube voltages, the phantom was exposed using automatic exposure control system （AEC）. The entrance surface dose（ESD） , dose area product（DAP） and mAs in every exposures were recorded. The image quality factors（IQF） of all images were calculated. Results With tube voltage increasing, ESD, DAP, mAs decreased and IQF value enhanced. There were statistically significance （ F = 45.15, 26.41, 29.26, 56. 53, P 〈 0.05 ）. ESD, DAP, mAs significantly increased with tube voltage less than 75 kV, began to decrease when tube voltage more than 75 kV, tended to be on the balance in 75 -80 kV. At the same time, the fluctuation of IQF value was no statistical difference in 50 - 75 kV of tube voltage, but was statistical significance in 75 - 90 kV （ F = 11.35, P 〈 0.05 ）. So, the image quality of adult upper airway with different tube voltage had no significant difference. Conclusions The appropriate tube voltage was 75 kV to 80 kV in the upper airway DR. The IQF value can be provided as the clinical evaluation index of image quality.