Cassette

Cassettes are rigid holders used in conventional and computed radiography (CR) for the screen film system and imaging plate respectively.

The back side of the cassette has a rubber or felt for adequate contact between screen film system or with the imaging plate. The front is made of low atomic number material (e.g. plastic or carbon) and the back is made of high atomic number material (e.g. lead) to reduce backscatter.

In case of conventional radiography, two screens are mounted on each side of the cassette, except in mammography, where a single screen is mounted on the back side. These cassettes have to loaded with film in the darkroom unlike the cassettes used in CR which can be loaded with imaging plate in the light.

The formats of the cassettes used in conventional radiology are: 13 x 18 cm; 18 x 24 cm; 24 x 30 cm; 20 x 40 cm; 30 x 40 cm; 35 x 35 cm; 35 x 43 cm; 30 x 90 cm.

No cassette is used in digital radiography.