Which of the following makes up a single DEL?

• A. Top electrode, a detection layer, bottom electrode
• B. Capture area, storage capacitor, TFT gate
• C. TFT gate, detection layer, storage capacitor
• D. Top electrode, capture area, bottom electrode

Answer: (B)

A single DEL is the pixel’s sensing unit and must include three functional parts: the area where signal is generated (capture area), a storage element to hold that signal until readout (storage capacitor), and a switch to address the pixel during readout (TFT gate). The capture area is the active region that collects charge produced by the X-ray–induced signal; the storage capacitor holds that charge so it can be read out later without leaking away; and the TFT gate acts as the selective switch that connects the pixel to the readout line when needed. Without any one of these, the pixel wouldn’t reliably capture and preserve the signal or be addressable for readout. The other descriptions either omit the storage element or the addressing switch, or reframe the components in a way that doesn’t reflect the essential, discrete sensing unit of a DEL.