Which component in the electronic imaging pathway emits electrons?

The photocathode is the component in the electronic imaging pathway that emits electrons when it is exposed to light. It is typically located just after the input phosphor in fluoroscopic systems. When the input phosphor converts incoming X-ray photons into visible light, this light then strikes the photocathode, which responds by emitting electrons in proportion to the intensity of the light it receives.

This electron emission is a crucial step in the conversion of X-ray images into a form that can be electronically processed and displayed, as it initiates the electronic imaging pathway by creating a flow of electrons that will ultimately lead to the formation of the final image on the output phosphor. Each emitted electron is responsible for contributing to the amplification process in the image intensifier, which results in a brighter and more detailed image. Understanding the role of the photocathode is essential for grasping how electronic imaging works, particularly in a context where low doses of radiation are used to obtain high-quality images.