Species: Feline   |   Classification: Miscellaneous

General

Fogging

Cause

  • Generalized:
    • Chemical fogging.
    • Heat.
    • Film beyond 'shelf life'.
    • Safelight intensity too high (should be <25W) or safelight too close to bench.
    • Safelight filter damaged or does not correspond to sensitivity of film.
  • Localized:
    • Film storage box not closed properly before switching on white light or opening darkroom door.
    • Pressure on films during storage.
    • Light switched on before film fully fed into automatic processor .
    • Cassette damaged so that light leaks in.
    • Damp storage conditions.
    • Cassette stored near X-ray machine or left on table during another exposure.

Remedy

  • Store films in cool dry conditions.
  • Ensure darkroom is light proof and safelighting appropriate.
  • Check cassettes are light proof and discard any which are damaged.

Static electricity marks

  • Black forked lightning marks   Film faults: static electricity  on the film.

Cause

  • Build up of static electricity.
  • Exacerbated by low humidity.

Remedy

Crimp marks

  • Usually small black crescent shaped marks   Film faults: crimp marks  on film.
  • May be white if made before exposure.

Cause

  • Rough handling of film when transferring in or out of cassette.

Remedy

  • Avoid creasing film.Tip film out of cassette rather than pushing at corners.

Screen marks

  • White marks on the film.

Cause

  • Dust or dirt on the screen, or foreign bodies in the cassette, preventing light from screen from reaching the film at a particular point.

Remedy

  • Clean screens regularly.

Other

  • Damage causing removal of areas of emulsion from film.
  • Finger prints   Film faults: poor washing  caused by dirty or greasy fingers eg hand cream contacting undeveloped film.
  • Roller marks - linear marks on the film.
  • Scratches in film emulsion   Film faults: scratched emulsion  caused by hangers, hopper, cassette and careless handling.Emulsion is particularly susceptible to damage when wet.

Cause

  • Build up of dirt or gelatin on rollers.

Remedy

  • Use care when handling film.
  • Clean rollers regularly and service processor periodically.

Exposure faults

Blur

Cause

  • Movement blur   Film faults: image unsharpness - movement blur  .
  • Poor film-screen contact.
  • Geometric unsharpness from large object-film distance.

Remedy

Poor positioning and centering

  • Area of interest not in the center of film   Film faults: mis-centered exposure  (or missed completely!).
  • Poor positioning may prohibit diagnosis from radiograph .

Cause

  • Poor knowledge of anatomy.
  • Animal is resistant to appropriate positioning or moves before exposure.

Remedy

  • Sedation.
  • Immobilization.
  • Familiarity with anatomy.
  • Knowledge of correct positioning and centering points.

Patient artifacts

  • Artifacts on image due to radio-opaque material on the body surface.

Cause

  • Dirty or wet coat (particular problem in large animal radiography .
  • Artifact overlying area of interest .

Remedy

  • Ensure coat is clean.
  • Remove radio-opaque objects eg leads and harnesses from field.

Double exposure

  • Two radiographic exposures made on same film .

Remedy

  • Improve working practices.

Inadequate identification

  • Radiographs should always be labeled with correct anatomical marker as well as patient details and date   Radiography: x-ray film  .
  • It is useful to include practice name too.

Image density faults

Film too pale
  • Image too pale but background exposed area of film, where no tissue penetration by x-ray beam, black.

Cause

  • Underexposure  Film faults: under exposure 
    • kV too low.
    • mAs too low.
    • Exposure time too short.
    • Focal-film distance too great.
    • Grid cut-off (vignetting) ie loss of density and emphasis of grid lines, usually worse towards the edge of the film.
    • Focused grid upside down.
    • Focused grid used at wrong focal-film distance.
    • Beam not centered to middle of focused grid.
    • Beam angled across grid.
  • Black exposed areas of film not dark enough (able to see finger held behind film).
  • Underdevelopment  Film faults: under development 
    • Developer too weakly constituted.
    • Developer exhausted.
    • Developer temperature too low.
    • Development time too short.
  • May also be due to underexposure - modern films respond to a limited range of kVs.

Film too dark

  • Exposed area of film too dark but clear emulsion in non-exposed areas.

Cause

  • Overexposure  Film faults: over exposure 
    • kV too high.
    • mAs too high.
    • Exposure time too long.
    • Focal-film distance too short.
  • Entire film too dark (image and unexposed edges of film).

Cause

  • Fogging
    • Film exposed to heat.
    • Film exposed to light.
    • Chemical fogging.
    • Film exposed to background radiation.
    • Film out of date.
  • Overdevelopment
    • Anything which speeds the development process or increased exposure to developer:
      • Developer over concentrated.
      • Developer temperature too high.
      • Development time too long.

Film lacks contrast

Cause

  • kV too high.
  • Grid required.
  • Closer collimation required.
  • Film underdeveloped.
  • Film overdeveloped.

Quantum mottle

  • Grainy appearance to film.

Cause

  • Insufficient exposure to affect all phosphor crystals in the intensifying screen.
  • Occurs in fast rare-earth film-screen combinations.

Remedy

  • Use a slower film-screen combination for selected examinations.

Processing faults

Chemical marks
  • Fixer splashes  Film faults: fixer splashes 01  appear as white patches on the film.
  • Developer splashesappear as black patches on the film.
  • Water splashes  Film faults: water splashes  are gray.

Cause

  • Untidy darkroom.
  • Incorrect darkroom procedures.

Remedy

  • Improve darkroom protocol.
  • Film hangers should be clean and dry before films are put in them to avoid edges of films being marked .
  • Films should be removed from hangers for drying.
  • Streaking results from poor developer agitation or from lifting film out of developer to view.

Generalized chemical staining

Cause

  • Insufficient washing.

Dichroic fog

  • Brown discoloration   Film faults: poor washing  .

Cause

  • Development continuing during fixation.

Remedy

  • Increase rinsing time to remove more developer, or consider adding acetic acid to rinse.
  • Change fixer as it may be exhausted.