Dark Room Equipments

Film cassettes:

  • A cassette is alight-tight metal container which is designed to hold the x-ray film and intensifying screens in close contact.

  • The front face which is of aluminum or plastic, faces the tube while the other side have a sheet of lead to absorbed back-scatter screens and cassettes are of course made in various sizes to correspond with standard film sizes.

Mounting intensifying screens in the cassette

  • Intensifying screens should be never be loose but must be properly mounted into the cassette.

  • Because certain adhesives interact with the screens it is advisable to use only the double-sided tape provided by the manufacturers.

The care of cassettes

  • Do not drop them on a hard floor

  • Do not trap the edges of the screens when the cassette is closed

  • Cassettes should be kept clean and there is always the danger of blood or urine leaking to the inside of the cassette. When a cassette must be placed in a dirty situation put it in a plastic bag.

Top Check for contrast

  • Good contrast between screens and the film in the cassette is vitally important. If radiographs should areas with loss definition, check the cassette.

Dry Bench

  • The dry bench is where the cassette are unloaded and recharged with fresh film. It must be impossible for splashes of developer to reach the dry bench surface.

  • The top of the dry bench must be large enough to accommodate the largest cassette in use when opened out.

  • The top surface should be either of wood or linoleum. Plastic laminates are not recommended because they hold static charges of electricity which can cause marks on films.

  • It is usual to store film boxes, especially those in current use , beneath the dry bench , either in a cupboard ( protected if near an X-ray set ) or in a film hopper.

  • The processing frames should hang above the bench , cash size on its appropriate. There are two designs of processing frame– the channel type and the clip type.

Top Wet Bench

  • The wet bench is where the processing of the films is carried out . It is possible to process the individual films in flat dishes but the method has a number of disadvantages and is not be recommended.

  • The usual method is to use a set of  tanks holding developer ,rinse water and fixer , and a larger tank for washing the films.


  • Standardized processing requires the developer to be at the optimum temperature of 20c (68 f).

  • The heater is put into the developer and the current switched on. On an average, the temperature will be raised by 1 degree per minute. In very cold weather it is also desirable to heat the fixer.

Washing Tank

  • The washing tank should be at least four times larger than the developer tank, with a supply of cold water constantly circulating through it, via a rubber hose, when films are being washed.

Top Drying

  • Films can be dried by removing them from the channel hanger, attaching a film clip, and hanging on a tensioned wire strung up in a dust-ree place.


  • X-ray film before processing is sensitive to white light; it must only be handled under safe-lighting.

  • A safe-light is a box containing a low wattage bulb behind a specified filter. This is a sheet of dyed gelatin between glass.

Two forms of safe light can be used in the radiographic dark room:

  • Direct: A diffuse light shines direct over the work point such as the dry and wet bench.

  • Indirect: the filtered light is directed up to the ceiling where it is reflected over the room.

Safe light efficiency

  • Safe light should be placed so that the work of the dark room can be done without fumbling. Where the dry and wet benches are separate, a small direct wall light should be provided for each.

Top  Processing room and equipment

  •  A radiographic processing room must capable of being made completely dark. The room must be kept clean and it should not be used for other purposes. A red, orange or yellow safe light may be used.

  • The arrangement of the dark room should provide easy accessibility during processing a bench for loading and unloading cassettes should be placed at one side of the room and the processing tanks at the opposite side the bench should be some distance from the processing tanks.

  • Immediately above or below the bench there should be space for storing film hangers. Unexposed x-ray film and cassettes should be stored in a cool dry place such as the processing room.

  • The processing equipment include a developing tank of sufficient size to contain a 14x17 inch x-ray film an  intermediate wash tank and  a fixer tank.

  • Processing tanks should be cleaned periodically, usually at every changes of solution. Sodium hypochlorite (Clorox) diluted in 4 parts of water is recommended for stainless-steel and hard-rubber tanks. These tanks should be scrubbed with a fiber brush. Top