What solid-state detector is a silicon chip that converts light or X-ray photons to an electrical charge or signal?

• A. Charge coupled device (CCD)
• B. Complementary metal oxide sensor (CMOS)
• C. Photomultiplier
• D. Scintillator

Answer: (A)

Solid-state detectors in digital radiography use a silicon chip to turn incoming photons into an electrical signal. A charge-coupled device is the classic example: photons reaching the silicon create electron-hole pairs, and that charge is moved across the chip to a readout amplifier, producing a voltage that becomes the digital image. In dental sensors, X-rays are often first converted to light by a scintillator, and that light is detected by the CCD, which then outputs a signal representing the image. CMOS sensors do a similar job, but the CCD is the traditional silicon-based device described as converting photons to an electrical charge or signal. A photomultiplier is not a solid-state silicon device, and a scintillator alone does not produce an electrical signal.