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目的通过分析计算机 X 线摄影(CR)系统的采样频率和栅密度频率,提出尽可能有效避免滤线栅伪影出现的抑制方法。方法实际测试不同栅密度的滤线栅与不同规格的成像板(IP)匹配使用,得到不同效果的图像;模拟2种信号频率(即2种栅密度的滤线栅),采用3种采样频率[6、8、10图像空间分辨率(pixels/mm)],得到不同的模拟图像效果。结果通过对比分析模拟图和实际图像,发现在采样频率正好等于信号频率的2倍时,可以得到正确的信号频率,图像清晰,无混淆现象。栅密度<4 LP/mm 时,可较好地与14 in×14 in、10 in×12 in(1 in=2.54 cm)IP 匹配使用。结论 CR 系统与普通 IP 匹配使用合适的采样频率和栅密度频率,可以有效避免滤线栅伪影出现。
Objective By analyzing the sampling frequency and gate density frequency of computerized radiography (CR) system, a method to suppress the emergence of grid artifacts as efficiently as possible is proposed. Methods The grids with different gate densities were actually tested and matched with different specifications of imaging plates (IPs) to obtain images of different effects. Two kinds of signal frequencies (ie grids with two kinds of grid densities) were simulated and three kinds of sampling frequencies [6, 8, 10 image spatial resolution (pixels / mm)] to get different analog image effects. Results By comparing the simulated image with the actual image, it is found that the correct signal frequency can be obtained when the sampling frequency is exactly equal to twice the signal frequency, the image is clear and no aliasing phenomenon occurs. Good gate density of <4 LP / mm matches IP of 14 in × 14 in, 10 in × 12 in (1 in = 2.54 cm). Conclusion Matching CR systems to common IPs using the appropriate sampling frequency and gate density frequency can effectively prevent the presence of grid artifacts.