What material is commonly used for the phosphor layer in modern image intensifiers?

In modern image intensifiers, Cesium Iodide is the material predominantly used for the phosphor layer due to its highly efficient conversion of X-ray photons into visible light. This efficiency is crucial for enhancing image quality as it allows for improved contrast and resolution. Cesium Iodide has a high atomic number, which increases the likelihood of interaction with incoming X-rays, thereby producing more light for equivalent X-ray exposure compared to older materials.

Additionally, the crystal structure of Cesium Iodide provides a columnar form that helps to minimize light scatter, further enhancing image clarity. This characteristic makes it particularly suitable for applications requiring high-resolution images, such as in fluoroscopy and digital radiography.

On the other hand, while Calcium Tungstate, Sodium Iodide, and Zinc Sulfide were historically used in older image intensifiers, they do not provide the same level of performance as Cesium Iodide in terms of light output efficiency and clarity in imaging. Thus, the preference for Cesium Iodide reflects advancements in technology focused on achieving better diagnostic imaging results in interventional radiology.