A radiation detector (10; 11; 12) used to detect incident radiation (RR) received at a first side (S1) of the radiation detector (10; 11; 12). The radiation detector (10; 11; 12) includes a scintillator (15) to convert the incident radiation (RR) into converted radiation (CR), a photosensor (20) arranged at a second side (S2) of the radiation detector (10) opposite to the first side (S1) to receive the converted radiation (CR) from the scintillator (15) and an interference optical filter (25) arranged between the scintillator (15) and the photosensor (20). Areas of the scintillator (15) on which the incident radiation (RR) impinges are intended to be imaged onto corresponding areas of the photosensor (20). The interference optical filter (25) is constructed to attenuate a portion of the converted radiation (CR) resulting from the incident radiation (RR) and impinging on a particular one (A1) of the areas of the scintillator (15) which is received via direct transmission through the interference optical filter (25) by another one (A3) of the areas of the photosensor (20) different from the one (A2) corresponding to the particular one (A1) of the areas of the scintillator (15). By using the interference optical filter (25), lateral optical crosstalk caused by the portion of converted radiation (CR) which laterally spread from the particular area (A1) of the scintillator (15) is reduced.