Each interaction with the screen produces a large number of what that causes the film to darken during development?

• A. Ultraviolet Photons
• B. Visible Light Photons
• C. X-Rays
• D. Heat

Answer: (B)

In screen-film radiography, the screen converts the incoming x-ray energy into light. Each interaction with the screen excites the phosphor to emit a large number of photons in the visible spectrum. Those visible light photons expose the film emulsion, forming a latent image that becomes visible as dark areas during development when the developer chemically reduces the exposed silver halide crystals to metallic silver. The film is designed to be sensitive to visible light, so this light is what causes darkening. Ultraviolet photons are not the primary emission of standard screens, x-rays don’t create the darkening during development in this context, and heat doesn’t drive the chemical changes that produce darkness.