In a CCD-based digital radiography system, which coupling method connects the scintillation layer to the CCD sensor chips?

• A. Lenses or fiber optics
• B. Thin-film transistors (TFTs) or CMOS
• C. Thin-film transistors (TFTs) or fiber optics
• D. Lenses or TFTs

Answer: (D)

Light produced by the scintillation layer must be delivered to the CCD with minimal loss and preserved spatial detail. The way to do this in a CCD-based indirect system is through optical coupling using lenses or fiber optics. Lens coupling uses an optical system to image or project the scintillator’s light onto the CCD, while a fiber-optic plate or fiber bundle channels the light directly from the scintillator to the CCD, helping to maintain light collection efficiency and spatial resolution. Thin-film transistors and CMOS are related to the readout electronics or sensor technology, not the light-transfer path between the scintillator and the CCD. So the effective coupling method is lenses or fiber optics.