数字化X射线摄影术曝光指数与曝光参数关系的实验研究  

Experimental study on relationship between exposure index and exposure parameters of digital X-ray photography

作　　者：周俊[1] 胡志[2] 温锐[2] 龙健胜 蔡裕兴[1] ZHOU Jun;HU Zhi;WEN Rui;LONG Jian-sheng;CAI Yu-xing(Department of Radiology,Nanfang Hospital,Southern Medical University,Guangzhou 510515,Guangdong,China;Department of Equipment,Nanfang Hospital,Southern Medical University,Guangzhou 510515,Guangdong,China)

机构地区：[1]南方医科大学南方医院放射科,广东广州510515 [2]南方医科大学南方医院设备器材科,广东广州510515

出　　处：《生物医学工程与临床》2021年第4期401-406,共6页Biomedical Engineering and Clinical Medicine

摘　　要：目的探讨数字化X射线摄影术(DR)曝光指数(EI)与曝光参数之间的关系、曝光参数值的改变对EI值的影响,以便利用EI来指导DR摄影时曝光参数值的合理选择。方法选择28 cm×28 cm大小和9.0、10.8 cm厚聚甲基丙烯酸甲酯(PMMA)板。西门子公司AXIOM Luminos dRF多功能数字化X射线机,配备2880×2880像素的碘化铯-非晶硅固体平板探测器。总滤过2.5 mmAL,滤线栅栅比15∶1。kV值选用81、102、125 kV和不同的mAs值组合,分别对9.0、10.8 cm厚PMMA板进行曝光,记录每次曝光图像的EI值;mAs值选用1.25、2.00、3.20 mAs和不同的kV值组合,分别对9.0、10.8 cm厚PMMA板进行曝光,记录每次曝光图像的EI值。结果当kV值及其他摄影条件不变时,EI值与mAs值间成正比关系;mAs点数值每增加一个点,EI值大小增加约25%。当mAs值及其他摄影条件不变时,EI值与kV值的关系符合指数函数关系,但指数值n并非固定不变,而是随着kV值的增加逐渐减小;当kV值小于100 kV时,kV点数值每增加一个点,EI值增加约25%;当kV值大于100 kV时,随着kV点数值的增加,EI值增加的比值有明显的下降。结论EI值与kV值和mAs值间的量化关系符合感光公式E=K(V^(n)·mAs)/r^(2),EI值可以作为反映感光量的量化指标。点数值表在DR摄影时仍然有重要的参考价值,但当使用高kV摄影时,kV点数值对应的kV值需要进行修正。Objective To study the relationship between digital X-ray photography(DR)exposure index(EI)and exposure parameters,and the effect of different exposure parameter values on EI value,and provide guidance for reasonable selection of DR exposure parameter value by EI value in digital radiography.Methods The polymethyl methacrylate(PMMA)panels with size of 28 cm×28 cm,thickness of 9.0 cm and 10.8 cm were selected.The Siemens multifunctional digital radiography system of AXIOM Luminos dRF was equipped with CsI/amorphous silicon flat panel detector of 2880×2880 pixels.The total filtration was equivalent to 2.5 mmAL,and gird ratio was 15∶1.The PMMA panels with thickness of 9.0 cm and 10.8 cm were exposed with exposure parameter of 81 kV,102 kV,125 kV combined with different mAs,and EI value of each exposure image was recorded.Meanwhile,PMMA panels with thickness of 9.0 and 10.8 cm were exposed with 1.25,2.00,and 3.20 mAs combined with different kV values,and EI value of each exposure image was recorded.Results The EI value was proportional to mAs value with kV value and other exposure parameters remained unchanged.With one point increase of mAs,the EI value increased about 25%.When mAs value and other photography conditions unchanged,the exponential function relationship between EI value and kV value was conformed,but exponential value n decreased with the increase of kV value.When kV value was less than 100 kV,EI value increased about 25%with each point increase of kV value.When kV value was greater than 100 kV,EI increase value decreased significantly with the increase of kV value.Conclusion It is demonstrated that the relationship between EI value,kV value and mAs value conforms to photosensitive formula E=K(V^(n)·mAs)/r^(2),EI can be used as the quantitative index reflecting the photosensitivity.The exposure point value table showed important reference value in DR,while kV value of exposure point value needs to be corrected in high kV.

关 键 词：曝光指数 曝光参数 点数值 数字化X射线摄影术(DR) 

分 类 号：R814.41[医药卫生—影像医学与核医学]