Giger M L, Doi K
Med Phys. 1984 May-Jun;11(3):287-95. doi: 10.1118/1.595629.
The effect of various digital parameters, such as the sampling aperture, sampling distance, and display aperture, on the modulation transfer function (MTF) of digital radiographic imaging systems was investigated by means of theoretical simulation studies. The MTFs were also determined experimentally to confirm the relationship used in the simulation studies. The results indicate that the overall MTF of a digital system cannot specify the resolution properties in the same way as can the MTFs of analog systems. The MTF of a digital system may include a "false" response due to aliasing, which could lead to an incorrect interpretation of the resolution properties. The magnitude of aliasing that will occur in a digitized signal depends on the sampling parameters chosen and on the frequency content of the radiologic object being imaged. Thus, the type of object to be detected as well as various digital parameters must be considered in the design and evaluation of digital imaging systems.
通过理论模拟研究，考察了诸如采样孔径、采样距离和显示孔径等各种数字参数对数字射线成像系统调制传递函数（MTF）的影响。还通过实验测定了MTF，以确认模拟研究中使用的关系。结果表明，数字系统的整体MTF不能像模拟系统的MTF那样以相同方式指定分辨率特性。数字系统的MTF可能包括由于混叠导致的“虚假”响应，这可能导致对分辨率特性的错误解释。数字化信号中发生的混叠幅度取决于所选择的采样参数以及所成像的放射学对象的频率内容。因此，在数字成像系统的设计和评估中，必须考虑待检测对象的类型以及各种数字参数。
