Receives radiation directly like film and deposits the energy in the electron wells or picture elements describes which device?

• A. Direct sensor
• B. Indirect sensor
• C. Scintillator
• D. CCD

Answer: (A)

Direct conversion detectors convert X-ray energy straight into electric charge within the detector itself. When radiation hits the sensor, it creates charge carriers that are collected and stored in each pixel’s potential wells (the electron wells) in amounts proportional to the energy deposited. This is why the device is described as receiving radiation directly and depositing energy in the electron wells or picture elements. Materials like amorphous selenium often serve as the photoconductor for this direct conversion, with the generated charge read out by the underlying electronics to form the image.

Indirect systems, by contrast, rely on a scintillator to first convert X-rays to visible light, which then travels to a photodetector (such as a CCD or CMOS) to produce the electronic signal. In that case, the energy is deposited in the scintillator as light, not directly in the detector’s electron wells. A CCD itself is a readout device used after the light from a scintillator is detected, whereas direct conversion refers to the detector layer where X-rays produce charge directly.