A plurality of optical transducers converts the first radiation to a first light having a first wavelength, and converts the second radiation to a second light having a second wavelength. A shielding unit is arranged between the optical transducers to shield the first radiation, the second radiation, the first light, and the second light. A plurality of first photoelectric converters that corresponds to each of the optical transducers outputs a first electrical signal based on intensity of the first light. A plurality of second photoelectric converters that corresponds to each of the optical transducers outputs a second electrical signal based on intensity of the second light.