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目的 测试计算机X线摄影 (computedradiography,CR)系统的总特性曲线。方法 利用常规X线机 ,采用时间阶段曝光法对成像板 (imagingplate,IP)曝光 ,经CR系统影像处理后 ,用密度计测量由激光打印在CR胶片上的不同密度楔的密度值并绘制特性曲线。结果 (1)CR系统总特性曲线受层次处理的影响 ;(2 )旋转量 (rotationamount,GA)为 0 8、1 4、2 4时 ,总特性曲线平均斜率分别为 1 98、3 10、3 75。 (3)随GA值的变化 ,总特性曲线绕设定的旋转中心 (rotationcenter,GC)转动。结论 根据诊断的目的和肢体不同部位来选择GA值 ,可得到不同对比度的影像。
Objective To test the total characteristic curve of computed radiography (CR) system. Methods Conventional X-ray machines were used to expose the imaging plate (IP) using the time-stage exposure method. After CR system image processing, densitometer was used to measure the density of different density wedges printed on CR film by laser and the characteristics curve. Results (1) The total characteristic curve of CR system was affected by the level of treatment. (2) When the rotationamount (GA) was 0 8,1 4,2 4, the average slope of the total characteristic curve was respectively 1 98,3 10,3 75. (3) As the GA value changes, the total characteristic curve rotates about the set rotation center (GC). Conclusion According to the purpose of diagnosis and different parts of the body to select the GA value, different contrast images can be obtained.