A method of removing residual charge from a photoconductive material includes applying a first voltage to the photoconductive material to form an electrostatic field during a collection operation in which x-rays are irradiated onto the photoconductive material; and applying a second voltage to the photoconductor to reduce an amount of residual charge therein during a removal operation, the second voltage being different from the first voltage. In one or more example embodiments, the photoconductive material may include Mercury Iodine (Hgl2).