What is the film emulsion layer made up of?

The film emulsion layer is primarily composed of silver halide crystals. These crystals are photosensitive and play a crucial role in the process of capturing images on radiographic film. When film is exposed to radiation, the silver halide crystals react to the incoming photons, undergoing a chemical change that allows them to form a latent image. Upon development, this latent image is transformed into a visible image through further chemical processes involving a developer and fixer solution.

Using silver halide crystals is essential because they provide the necessary sensitivity and resolution for capturing detailed images. This property is foundational to radiographic imaging, enabling the accurate representation of internal structures within the body. Other materials mentioned in the choices, such as lead oxide or aluminum particles, do not serve the same purpose and are not part of the film emulsion layer.