A pixel device having an improved energy resolution includes at least one photodiode and at least one voltage supply unit for applying a voltage to the photodiode. The pixel device includes a voltage storage unit and a voltage adjusting unit. In a precharge mode, the voltage storage unit stores a first anode voltage. In a sensing mode, the voltage adjusting unit adjusts a second anode voltage of the anode of the photodiode to be the same as the first anode voltage stored in the voltage storage unit.
