A combined scintillation crystal includes: at least one scintillation crystal A module and a scintillation crystal B module. The scintillation crystal A module and the scintillation crystal B module are scintillation crystal modules with different performances. The scintillation crystal A module comprises at least one scintillation crystal A, and the scintillation crystal B module comprises at least one scintillation crystal B. The sensitivity of the scintillation crystal A is lower than the sensitivity of the scintillation crystal B, and the light output ability of the scintillation crystal A is higher than the light output ability of the scintillation crystal B. The scintillation crystal B module includes a ray incidence plane for receiving rays, and the at least one scintillation crystal module A is arranged at the outer side of the ray incidence plane of the scintillation crystal B module.
