Radiologic Technologist Practice Exam

What does the photomultiplier tube in a phosphor plate reader system convert?

1. Light to electrons

2. X-rays to electrons

3. Light to digital values

4. X-rays to digital values

The correct answer is: Light to electrons

The photomultiplier tube in a phosphor plate reader system is designed to convert light into electrons. When the phosphor plates are exposed to radiation, they absorb the energy and release light through a process known as photostimulated luminescence. The light emitted from these plates is then captured by the photomultiplier tube. Once this light enters the photomultiplier tube, it gets converted into a proportional electrical signal, which consists of an abundance of electrons being generated in response to the light photons. This process of amplification enables the system to detect very faint light signals, ultimately allowing for the transformation of the detected light into meaningful data for image processing. The other options involve different conversions that do not accurately describe the role of the photomultiplier tube in this system. The conversion of X-rays to electrons typically occurs within the detector components of imaging systems, and the conversion of light to digital values or X-rays to digital values involves subsequent processing steps outside the immediate function of the photomultiplier tube.