The present disclosure provides a collimator. The collimator includes a slice module, a filter module, and a support and protection module. The slice module and the filter module are detachably connected with the support and protection module. The rays strike on the collimator and pass through the slice module and the filter module in order. The slice module is configured to adjust the fan-beam width of the rays striking on the collimator. The filter module is configured to make the rays pass through different filters to implement different types of scanning.
