A radiation detector comprising: a two-dimensional array of upper scintillators (30 T) disposed facing an x-ray source to receive radiation therefrom, convert lower- energy radiation into visible light and transmit higher energy radiation; a two-dimensional array of lower scintillators (30 B) disposed adjacent the upper scintillators (30 T) distally from the x-ray source to convert the transmitted higher energy radiation into visible light; arrays of first and second light sensitive elements (38 T, 38 B) to view the visible light and convert the visible light into electrical signals, the first light sensitive elements (38 T) being optically coupled to the upper scintillators (30 T) and the second light sensitive elements (38 B) being coupled with the lower scintillators (30 B), characterised by: a first interference filter between an active area of each first light sensitive element (38 T) and the scintillators (30 T, 30 B), the first interference filter having a light wavelength (/1), which matches a light wavelength ( l 2) emitted by the upper scintillators (30 T), to restrict radiation wavelengths received by the first light sensitive elements (38 T) to the wavelengths emitted by the upper scintillators (30 T), and a second interference filter between an active area of each second light sensitive element (38 B) and the scintillators (30 T, 30 B), the second interference filter having a light wavelength ( l 3), which matches a light wavelength ( l 4) emitted by the second scintillators (30 B), to restrict radiation wavelengths received by the second light sensitive elements (38 B) to the wavelengths emitted by the lower scintillators (30 B). a two-dimensional array of upper scintillators (30 T) disposed facing an x-ray source to receive radiation therefrom, convert lower- energy radiation into visible light and transmit higher energy radiation; a two-dimensional array of lower scintillators (30 B) disposed adjacent the upper scintillators (30 T) distally from the x-ray source to convert the transmitted higher energy radiation into visible light; arrays of first and second light sensitive elements (38 T, 38 B) to view the visible light and convert the visible light into electrical signals, the first light sensitive elements (38 T) being optically coupled to the upper scintillators (30 T) and the second light sensitive elements (38 B) being coupled with the lower scintillators (30 B), characterised by: a first interference filter between an active area of each first light sensitive element (38 T) and the scintillators (30 T, 30 B), the first interference filter having a light wavelength (/1), which matches a light wavelength ( l 2) emitted by the upper scintillators (30 T), to restrict radiation wavelengths received by the first light sensitive elements (38 T) to the wavelengths emitted by the upper scintillators (30 T), and a second interference filter between an active area of each second light sensitive element (38 B) and the scintillators (30 T, 30 B), the second interference filter having a light wavelength ( l 3), which matches a light wavelength ( l 4) emitted by the second scintillators (30 B), to restrict radiation wavelengths received by the second light sensitive elements (38 B) to the wavelengths emitted by the lower scintillators (30 B). a first interference filter between an active area of each first light sensitive element (38 T) and the scintillators (30 T, 30 B), the first interference filter having a light wavelength (/1), which matches a light wavelength ( l 2) emitted by the upper scintillators (30 T), to restrict radiation wavelengths received by the first light sensitive elements (38 T) to the wavelengths emitted by the upper scintillators (30 T), and a second interference filter between an active area of each second light sensitive element (38 B) and the scintillators (30 T, 30 B), the second interference filter having a light wavelength ( l 3), which matches a light wavelength ( l 4) emitted by the second scintillators (30 B), to restrict radiation wavelengths received by the second light sensitive elements (38 B) to the wavelengths emitted by the lower scintillators (30 B).