The capture area of a detector element is defined by which combination of components?

• A. Capture area, storage capacitor, and TFT gate
• B. Top electrode, detection layer, and bottom electrode
• C. Top electrode, capture area, and bottom electrode
• D. Thin film transistor (TFT) gate, detection layer, and storage capacitor

Answer: (D)

The area that captures X-ray energy and holds the resulting signal is defined by the overlap of three essential parts: the detection (photosensitive) layer, the storage capacitor, and the thin-film transistor (TFT) gate. The detection layer is where X-rays are converted into charge; the storage capacitor holds that charge until readout; and the TFT gate controls the charge flow, effectively setting the active region of the detector element. Together, these components establish the physical boundary and capacity of one detector element. Without any one of them—no detection layer to generate charge, no storage capacitor to store it, or no TFT gate to define and address the region—the capture area wouldn’t be properly defined.