Why is X-ray film packaged in a foil bag?

The packaging of X-ray film in a foil bag primarily serves to protect against excessive humidity. X-ray films are sensitive to moisture, which can significantly affect their performance and image quality. Humidity can cause fogging of the film, leading to a decrease in the sharpness and clarity of the captured images. The foil bag acts as a moisture barrier, ensuring that the film remains dry and stable before use.

While other factors like heat, radiation fog, and mechanical damage can impact the quality and integrity of X-ray films, the specific role of the foil bag is most critically tied to its ability to safeguard the film from moisture exposure. Humidity control is essential in maintaining the proper conditions for film storage and handling, ultimately preserving the image quality upon development.