CAMRT Radiography Practice Exam

What is the function of the input phosphor in the image intensifier tube?

1. It amplifies x-ray photons

2. It converts x-ray photons to visible light photons

3. It captures the final image

4. It filters unwanted radiation

The correct answer is: It converts x-ray photons to visible light photons

The input phosphor in the image intensifier tube serves the essential function of converting x-ray photons into visible light photons. This process is crucial because x-ray photons have high energy but are not visible to the human eye. The conversion takes place when the x-ray photons strike the input phosphor, typically made of a material like cesium iodide. The resultant visible light photons then proceed to the next stage in the image intensifier tube, where they can be further processed and amplified to produce a clearer and more usable image for diagnosis. This function is the first step in the image intensifier system, emphasizing the significance of light production in the visualization of the x-ray image. The other options do not describe the role of the input phosphor. For instance, amplification of x-ray photons happens later in the process, when the light is converted into an electrical signal and then amplified. The final image is produced by the output phosphor, and filtering of unwanted radiation is a separate function provided by other components in the imaging system.