Species: Feline   |   Classification: Techniques

Introduction Requirements Preparation Procedure Aftercare Outcomes Further Reading



  • Radiography is used as an aid to diagnosis and for monitoring of treatment.

Alternative Techniques

  • Automatic processing Radiography: processing.
  • Smaller models can be found in many veterinary practices.
  • In general produce results:
  • More rapidly (90-180 seconds).
  • More consistently.
  • More easily.

Time Required


  • Dark room must be maintained regularly to ensure consistent production of high quality radiographs.


  • Approximately 10 minutes processing time for a single radiograph.


Materials Required

Minimum equipment

  • Light-proof room.
  • Three trays or tanks for chemicals
  • Developer.
  • Fixer.
  • Wash water.
  • Film holders either channel hangers or clip hangers if using vertical processing tanks.

Ideal equipment

  • Tank heaters with thermostat to maintain developer at correct temperature.
  • Safelight - light of wavelength (color) beyond sensitivity of film Radiography: x-ray film.
  • Safelight can be checked by removing a piece of exposed film from cassette in dark room then covering center strip with thick card.
  • Turn on safelight and move card down 2 cm and leave for 4 mins, move again 2 cm and leave for 2 mins, then expose section of film for 1 min, 30 secs, 20 secs, 10 secs.
  • Film is then developed and examined to see after what time there is a noticeable increase in the density of the emulsion exposed to the safelight.
  • A safelight should not increase exposure of film in the time taken to process film in the darkroom.
  • Dark room divided into dry and wet areas.
  • Timer with audible signal to allow accurate timing of development.

Minimum consumables

  • Fresh chemicals: developer and fixer.




Step 1 - Prepare darkroom

  • Turn on safelight and turn off mainlight.
  • Ensure that door is locked and room is light-tight.
  • Allow a few minutes for eyes to become accustomed to the dark.
  • Stir the developer and fixer to equalize the temperature and distribution of chemicals throughout the solutions.
  • Developer temperature should be 20°C.

Step 2 - Remove film from cassette

  • Under safelighting remove the film from the cassette - handling only by a corner. Tip film out rather than rubbing at corner - risk of crimping.
  • Close cassette to prevent splashing or dirtying of screen.
  • Label film if appropriate ie with darkroom identification marker.
  • Attach to a film hanger.

Core Procedure

Step 1 - Developing

  • Immerse film smoothly in the developer solution and note time or set timer.
  • Film should remain in developer for 4 minutes.
    Ensure that film is not in contact with adjacent film or side of tank during this process.
  • Agitate the hanger with an up and down motion to ensure that the film keeps coming into contact with fresh developer.
  • At end of 4 minutes remove film from tank.
  • Development time for non-screen film should be increased by about 1 minute.
    Do not allow developer solution to run off film back into developer tank.

Step 2 - Rinsing

  • Place the film in rinsing tank for at least 10 seconds agitating the hanger throughout.
  • Remove film from water.

Step 3 - Fixing

  • Immerse the film in the fixer tank.
  • After approximately 30 seconds film emulsion should clear.
    Do not expose film to white light until emulsion has cleared, plus the same time interval again   Radiography: processing  .
  • Standard film should remain in fixing tank for at least 15 minutes.
  • Non-screen film has thicker emulsion and fixing may take several minutes longer.
    Film may be viewed initially to assess quality after fixing time

Step 4 - Washing

  • After full fixing place the film in wash compartment for at least 30 minutes.
    Water must be flowing continuously or washing will not be efficient.

Step 5 - Drying

  • Remove film from channel hangers to dry to avoid the edges of the film remaining wet.
  • Film should be hung in low-humidity, dust-free environment with circulating air.
  • Film should not be read finally until emulsion is completely dry.


Step 1 - Reload cassette

  • Ensure that hands are clean and dry.
  • Double-check that door is locked and that no white light is entering dark room.
  • Open cassette and leave on work surface.
  • Remove film from film box or hopper.
  • Place film on screen in open cassette, taking care that film is not trapped at edge of cassette.
  • Replace lid on open box of film or close hopper.
  • Close cassette and ensure clips shut tightly.
  • Recheck film box or hopper to ensure that they are light-tight before opening darkroom door or turning on light.



Reasons for Treatment Failure

  • See Radiography: film faults Radiography: film faults.
  • Film incorrectly stored prior to exposure.
  • Rough handling of film.
  • Room not light-tight   →   fogging of film.
  • Processing performed at wrong temperature.
  • Chemicals out of date or exhausted.
  • Insufficient developing, fixing or washing time allowed.

Further Reading


Refereed papers