Radiologic Technologist Practice Exam

Where are electrons stored until a photostimulable phosphor plate (PSP) is processed?

1. valence band

2. photodetector

3. conduction band

4. conductive layer

The correct answer is: conduction band

Electrons are stored in the conduction band of a photostimulable phosphor plate (PSP) following exposure to ionizing radiation. When the PSP is exposed, electrons are excited from the valence band to the conduction band, creating a latent image within the phosphor. The conduction band can hold these energized electrons until the plate is processed. During the processing phase, the PSP is illuminated with a scanning laser, which causes the stored electrons in the conduction band to return to the valence band, releasing energy in the form of light, which is then captured to create the final image. The valence band is where electrons normally reside and does not store the excited electrons after exposure. A photodetector is not a storage location but rather a device that detects the emitted light during the processing phase. The conductive layer is used primarily for electrical connectivity within the imaging plate and does not serve the function of storing excited electrons. Understanding these concepts is crucial for mastering PSP technology and ensuring high-quality radiologic imaging.