What is the input phosphor made of?

The input phosphor is primarily made of cesium iodide. This substance is commonly used in fluoroscopic imaging because of its efficient conversion of x-ray radiation into visible light. When x-rays strike the cesium iodide, it emits light, which is then directed towards the photosensitive components of the imaging system, such as the image intensifier or flat-panel detector.

Cesium iodide's favorable properties include a high atomic number, which improves its x-ray absorption capabilities, and the ability to produce light efficiently. Additionally, cesium iodide can be structured into a needle-like crystalline form, enhancing its light output and minimizing scatter, which contributes to better image quality.

In contrast, lead oxide, gallium arsenide, and aluminum oxide have different applications or properties that do not make them suitable as the primary material for the input phosphor in fluoroscopy. Lead oxide is often used for radiation shielding, gallium arsenide is used in semiconductor applications, and aluminum oxide does not provide the specific light output characteristics required for the input phosphor.