计算机射线检测（CR）中，后置防护板（后板）的种类对成像质量具有一定的影响。通过试验对比了不同管电压时，采用不同材料和组合后板得到的数字图像质量，分析了产生差别的原因。提出了在管电压为90 kV或以下时，宜采用后置钢屏或不采用任何后板的方式进行检测，达到100 kV或更高后，宜采用后置铅板或钢屏+铅板进行检测。

The type of rear protection plate (backplate) has a certain influence on the imaging quality in CR testing. The quality of digital image while changing backplate and tube voltages was compared and the reasons for the differences were then analyzed. It was proposed that while tube voltage being below 90 kV, either applying a rear steel screen or no screen could be adopted, whereas on the other hand, using rear lead plate or steel screen with lead plate should be better with the tube voltage being higher than 100 kV.