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目的:分析CR系统自动曝光控制(电离室)X线摄影特点,探讨图像后处理技术对影像质量的影响。方法:①以A、B、C3组(每组180例)不同组合的kV、mAs、密度补偿、感速、探测野等,对胸部拟人水模及IP板自动曝光控制摄影;②检测3种组合患者影像不同曝光条件、曝光指数、kV与mAs变化及照片密度值。结果:①A组125kV与0.6~1.0mAs组合,图像对比度差;低密度偏高;信噪比低;量子斑点多噪声大。②B组70~85kV与5~30mAs组合,图像对比度好;层次清楚;锐利度高;量子斑点少噪声小。A、B两组差异有显著意义,P<0.001。③C组42~52kV与5~20mAs组合,图像对比度高;层次清楚;锐利度高;量子斑点少噪声小。B、C两组差异没有统计学意义(P>0.05)。④测量胸片、腰、颈椎等的密度值均在0.8~1.30范围内。结论:CR系统自动曝光控制不宜采用高kV或太低kV摄影,检测病灶细微结构应使用尺寸相对较小的成像板。数字化摄影图像信息后处理技术,保证了照片质量,提高了影像学诊断范围及准确率。
Objective: To analyze the characteristics of CR system automatic exposure control (ionization chamber) X-ray photography and discuss the influence of image post-processing technique on image quality. Methods: ①According to different combinations of kV, mAs, density compensation, sensory speed and exploration field in groups A, B and C3 (180 cases in each group) Combination of patient images under different exposure conditions, exposure index, kV and mAs changes and photo density values. Results: ①A group of 125kV and 0.6 ~ 1.0mAs combined, the image contrast is poor; low density high; low signal to noise ratio; quantum dot noise more. ② group B 70 ~ 85kV and 5 ~ 30mAs combination, the image contrast is good; level clear; high sharpness; quantum spots less noise. A, B two groups have significant differences, P <0.001. ③C group 42 ~ 52kV and 5 ~ 20mAs combination, the image contrast is high; the level is clear; high sharpness; quantum dot less noise. There was no significant difference between B and C (P> 0.05). ④ measurement of chest radiograph, waist, cervical spine and other density values are in the range of 0.8 ~ 1.30. Conclusion: The automatic exposure control of CR system should not adopt the high kV or too low kV photography. The imaging plate with relatively small size should be used to detect the fine structure of the lesion. Digital photographic image information post-processing technology to ensure the quality of the picture to improve diagnostic accuracy and diagnostic imaging.