Last revised by Mateusz Wilczek on 14 Nov 2023

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

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

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