数字X线摄影中曝光指数对曝光量定量化指导的研究

The Relationship between Exposure Index(EI) and Exposure in Digital X-ray Photography:a Quantitative Guide

目的探讨曝光指数与曝光量之间的关系,在实际工作中可根据曝光指数对摄影条件进行修正以实现定量化。资料与方法 Kodak Directview DR5100,SID=100cm,8块有机玻璃板,固定70kV,分别用P值点数即从2.5至160mAs进行曝光,记录设备上显示的EI(exposure index,EI)值。用Spss13.0统计软件包对所得到的数据进行统计作图得出EI与点数P之间的拟合关系。并根据Kodak公司的EI计算公式进行理论验证此关系。结果 EI与P之间存在量化关系,其拟合关系方程为:EI=191.223+93.071P,相关系数r=0.999。用理论验证EI与P之间存在量化关系。结论通过此试验可以得出EI与曝光量之间的关系:P值每变化一个点EI值就相应近似变化100。可根据曝光指数对曝光量进行量化修正。

purpose To explore the relationship between EI（Exposure Index,EI）and exposure,and to understand the quantitative adjustment of exposure according to the EI in digital X-ray photography.Materials and Methods Kodak DirectView DR 5100 was utilized with SID = 100 cm and 8 pieces of PMMA.The tube voltage was fixed at 70 kV.The EI（exposure index,EI）shown on the equipment was recorded after each exposure from 2.5 to 160 mAs according to P value.The data were analyzed using SPSS 13.0 software for a fitting equation between EIs and P values.This relationship was verified according to the Kodak equation of EI of.Results There is a quantitative relationship between EI and P and the fitting equation is EI = 191.223 ＋ 93.071P.The correlation coefficient（r= 0.999）.Conclusions The relationship between EI and exposure is that when P changes a point,EI changes approximate 100.Exposure can be adjusted according to the EI