A detector array (112) includes at least one detector pixel (306) with a cavity (400) that defines a three dimensional volume. A surface of the cavity includes at least two photosensitive regions and a non-photosensitive region there between, defining at least two sub-pixels (306i, 3062) which detect light photons traversing within the three dimensional cavity and produce respective signals indicative thereof. The detector array further includes a scintillator (302), including a first sub-portion that is located in the cavity and which emits the light photons in response to absorbing x-ray photons. Light photons emitted by the first sub-portion are detected by both of the at least two sub-pixels