A detector unit (301) for detecting electromagnetic radiation (106), the detector unit (301) comprising a conversion material (332) adapted for converting impinging electromagnetic radiation (106) into electric charge carriers, a charge collection electrode (331) adapted for collecting the converted electric charge carriers, a shielding electrode (334, 335) adapted to form a capacitance with the charge collection electrode (331), and an evaluation circuit (312 to 315) electrically coupled with the charge collection electrode (331) and adapted for evaluating the electromagnetic radiation (106) based on the collected electric charge carriers.