An apparatus, system and method suitable for detecting X-ray are disclosed. In one example, the apparatus comprises: an X-ray absorption layer and a mask; wherein the mask comprises a first window and a second window, and a portion between the first window and the second window; wherein the first and second windows are not opaque to an incident X-ray; wherein the portion is opaque to the incident X-ray; and wherein the first and second windows are arranged such that charge carriers generated in the X-ray absorption layer by an X-ray photon propagating through the first window and charge carriers generated in the X-ray absorption layer by an X-ray photon propagating through the second window do not spatially overlap.