Of what material is the image intensifier's input phosphor usually made?

• A. Lead oxide
• B. Copper sulfate
• C. Cerium fluoride
• D. Cesium iodide

Answer: (D)

The input phosphor of an image intensifier is typically made of cesium iodide. This material is chosen for its excellent properties in converting x-ray photons into visible light photons, specifically in the blue-green spectrum. Cesium iodide has a high atomic number, which enhances its ability to absorb x-ray energy efficiently, thereby improving the overall image quality generated by the image intensifier.

Additionally, cesium iodide has a crystalline structure that allows it to produce a more uniform light output and minimize light scattering. This results in sharper images with better resolution. The effectiveness of cesium iodide makes it a preferred choice in the construction of image intensifiers utilized in fluoroscopy and other radiographic imaging techniques.

The other materials listed, such as lead oxide, copper sulfate, and cerium fluoride, do not possess the same combination of properties that cesium iodide has, making them less suitable for the input phosphor function in image intensifiers.