数字X线摄影系统适宜曝光量差别的研究

目的 探讨数字X线摄影系统适宜曝光量设置方法,以确保图像质量和降低受检者受辐射剂量.方法 以树脂体模和对比度-细节测试体模(CDRAD2.0)为被照体,使用碘化铯探测器和硫氧化钆探测器的两种数字X线系统进行不同曝光参数成像.记录体模表面空气吸收剂量并进行秩和检验,用CDRAD分析软件计算图像质量因子函数(IQFinv),对相同曝光条件下的IQFinv值进行配对t检验,根据IQFinv值和系统感度确定这两种数字X线系统的适宜曝光量.结果 不同曝光条件下,两种数字X线系统体模表面空气吸收剂量差异没有统计学意义(P>0.05).碘化铯和硫氧化钆两种探测器的数字X线系统平均IQFinv值在125 kV时分别为4.89±1.01和2.47±0.25,70 kV时平均为5.10±1.05和2.38±0.43,相同曝光条件下两种数字X线系统IQFinv值差异有统计学意义(t值分别为6.509、10、158、P值均<0.05),碘化铯和硫氧化钆两种探测器的数字X线系统适宜曝光量之比约为1:2.结论 以IQFinv值为参考,可以量化不同数字X线系统最适曝光量差别,为正确设置曝光参数提供依据.

Comparison of adaptive exposure dose in digital X-ray imaging system

Objective To evaluate the difference of adaptive exposure dose in two digital X-ray imaging systems. Methods Resin phantom and contrast-detail test phantom were used on Cesium iodide and Gadolinium oxide sulfide plate imaging detector DR systems using difference exposure parameters. All entrance surface dose were recorded, Image quality index (IQFinv ) was calculated by CDRAD analysis software. The optimal exposure radiation dose was determined according to the sensitivity and IQFinv. Results There were no significant differences of entrance surface dose between two digital X-ray systems on two different exposure parameters with 70 kV ( P > 0. 05) , while there were significant differences with 125 kV(P < 0.05) . The maximum difference was 28. 57% . The mean IQFinv value of Cesium iodide detector DR and Gadolinium oxide sulfide detector DR with 125 kV and 70 kV were 4. 89 ±1. 01 and 2.47 ±0.25, 5. 10 ±1.05 and 2.38 ±0.43, respectively. There were significant diferences between the two systems under the same exposure parameters (t = 6. 509,10. 158, P < 0. 05). The optimal exposure dose ratio between Cesium iodide and Gadolinium oxide sulfide detector DR system was 1:2. Conclusion According to the IQFinv value, the adaptive exposure parameter can be adjusted to achieve good image quality with low radiation dose on different digital radiography systems.