对于任何检测工作，选择探测器系统的基本考虑是其基本空间分辨力和规格化信噪比两个参数。基本空间分辨力一般应依据采样定理选择。一般，应先按理论确定线型像质计灵敏度，然后按该灵敏度确定检测图像的最大空间频率要求，再确定对应的采样频率。当规定了检测标准时，可依据检测图像不清晰度选择。规格化信噪比应按相关标准要求选择。

For any testing problem, the essential attention for selection a detector system is the basic spatial resolution and the normalized signaltonoise ratio of the digital detector system. The selection of the basic spatial resolution shall follow the sampling theorem. The selection process might be as follows. First of all, the wire IQI sensitivity should be given, and then the maximum spatial frequency of the image upon the wire IQI sensitivity should be determined. Finally, the correspondent sampling frequency with the maximum spatial frequency should be calculated. When radiographic standard was specified, the selection may depend on the specified unsharpness of the image. The normalized signaltonoise ratio value was selected on the requirement in the using radiographic standard.