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     on the film.

Cause

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

Remedy

• Handle film carefully to minimize static build up.
• Clean screens   Radiography: cassette and intensifying screen  regularly to avoid static build up.

Crimp marks

• Usually small black crescent shaped 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     caused by dirty or greasy fingers eg hand cream contacting undeveloped film.
• Roller marks - linear marks on the film.
• Scratches in film 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

Image density faults

Processing faults

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Winstanley T D (1996) Salvaging dark dental radiographs. Dent Update 23 (6), 246, 249 PubMed.
• Kirberger R M, Roos C J (1995) Radiographic artifacts. J S Afr Vet Assoc 66 (2), 85-94 PubMed.
• Sharpe P (1985) Film faults and CT imaging. Radiography 51 (595), 29-30 PubMed.