An imaging system (10) comprises at least one radiation detector unit (16) disposed adjacent a field of view (20) to detect and measure radiation from the field of view (20). The detector unit (16) includes multiple detection modules (18) which each detects radiation from a prespecified region of the field of view (20), each region being a fraction of the field of view. One or more pinholes (52) are associated with the detector unit (16). Each pinhole (52) receives radiation from the prespecified region of the field of view (20) and transmits radiation to one or more associated detection modules (18).