What device is a metal, plastic, or cardboard light-tight container that holds a plate receptor for extraoral imaging?

• A. Cassette
• B. Holder
• C. Receptor case
• D. Film canister

Answer: (A)

For extraoral imaging, the receptor must be protected from light and kept in a single, stable unit during exposure and handling. The device that does this is the cassette. It’s a light-tight enclosure made of metal, plastic, or cardboard that holds the plate receptor (film or digital plate) and, in film-based systems, often contains intensifying screens to help convert X-rays into light for exposure, allowing lower radiation doses. This setup keeps the receptor safe from ambient light and physical damage while images are being taken.

The other options don’t fit because a holder is used to position the receptor inside the mouth for intraoral radiographs, not for extraoral work. A receptor case might refer to storage or transport but isn’t the standard light-tight imaging container used during extraoral exposure. A film canister is a small light-tight tube for intraoral films, not the larger protective container used for extraoral plates.