31: Radiographic Faults

Radiographic Faults

Ravikiran B.N. Ongole and Praveen

➧. Errors in Film Storage and Handling

Emulsion Peel and Scratched Film

Dark Spots or Lines

Static Electricity Artifact

Nail Marks or Kink Marks

➧. Errors in Film Placement and Projection Technique

Herring Bone Effect, Tyre Mark Pattern, Raised Diamond Markings/Knurled Effect

Slanting of the Occlusal Plane

Apical Ends of the Teeth Not Imaged (Partial Image)

Crown Portion of Teeth Not Imaged (Partial Image)

Overlapped Image

Fore-shortened Image

Elongated Image (Total)

Elongated Image (Partial)

➧. Errors in Exposure Parameters and Processing Technique

Blank Radiograph

Dark Radiograph

Light Radiographs

Insufficient Contrast

Yellow or Brown Stains

Blisters on the Film

Dark Spots on the Radiograph

Light Spots on the Radiograph

Emulsion Wash Away

Reticulation of Emulsion

No Image/Blank Radiograph

➧. Artifacts

A radiograph is considered ideal when it is dimensionally accurate, covers the area of interest completely and has optimum density and contrast. When the above criteria are not met the radiograph is termed faulty. A faulty radiograph is non-diagnostic and necessitates retaking the radiograph which leads to unnecessary patient exposure.

Causes of faulty radiograph

Radiographic faults can occur at any stage in the radiographic process, right from handling and storing of films to the processing. The causes for radiographic faults can be categorized as:

Errors in film storage and handling

Errors in film placement and projection technique

Errors in exposure parameters and processing technique

Errors in Film Storage and Handling

These can occur prior to the radiographic exposure and after the processing especially before the film is completely dry.

Film Fog

The overall appearance of the radiograph is dark. The radiographic image will show decreased image contrast and detail and as some authors believe they appear as though the radiographs are being viewed through a fog thereby obscuring the image (Figure 1).

Figure 1 Fogged radiograph

Causes

Films stored at high temperatures and humidity

Films exposed to extraneous radiation.

Ideal film storage temperature is between 50^°F and 70^°F (10–20^°C) and between 30% and 50% relative humidity. Any increase is known to cause increased sensitization of the film emulsion. The expiry date of the film packets have to be checked and it is also recommended that the radiology unit stocks only sufficient number of film packets that can be used within 2 months’ time.

Extraoral films should be stored in a vertical orientation to prevent pressure artifacts.

Emulsion Peel and Scratched Film

Emulsion is coated onto the plastic supportive base of the film and it adheres to the base via a coat of adhesive agent. However, during the developing process, the emulsion is rendered soft to aid in the rapid diffusion of the developing agents into the emulsion and reacts with the silver halide grains. However, the hardeners in the fixing solution shrink and harden the gelatin to prevent its damage. White lines appear when the soft film emulsion is removed from the film base by sharp objects.

Causes

Wet film in contact with finger nails or other sharp objects such as film clips (Figure 2A, B).

Figure 2 (A) Emulsion peel. (B) Scratched film

Placing wet films on unclean surfaces.

After processing, films must not come into contact with each other until completely dry as the wet emulsions can stick together and peel off the emulsions when they are separated.

Care must be taken when placing the film holder in the processing solutions and drier. Avoid contact with other film hangers and with the tank walls.

Dark Spots or Lines

Cause

Finger print contamination.

Dark finger marks: from improper handling of the film (holding the film with greasy fingers on the surface of the film, especially when the fingers are contaminated with developer solution).

Clear finger marks or white fingerprint marks can be caused by fixer solution or oily substances on the fingers that prevent the emulsion from developing.

Films should be held by the edges only.

Static Electricity Artifact

Causes

Static electricity artifacts are formed due to the build-up of electrons in the emulsion. They are frequently caused by low humidity/dry weather or static producing objects such as synthetic materials used in uniforms. Moreover, when films are removed from the film packet or the cassette too rapidly in a dry atmosphere, a small charge of electricity can be released producing these artifacts.

Static artifacts have two common appearances: tree like and smudges. Tree like artifacts (Figure 3) are produced when films are unwrapped rapidly and appear as black lines running across the film and smudge static electricity is produced by polyester clothing and appear as black smudges on the film.

Figure 3 Static electricity artifact on a panoramic film

Nail Marks or Kink Marks

Appear as a crescent shaped radiolucent finger nail marks (Figure 4).

Figure 4 Crescent shaped nail mark

Cause

Excessive bending of the film.

Errors in Film Placement and Projection Technique

Herring Bone Effect, Tyre Mark Pattern, Raised Diamond Markings/Knurled Effect

A lead foil is placed within every intraoral radiographic film packet to prevent unnecessary exposure to surrounding structures from the residual X-ray beam and also protects the film from back scatter or secondary radiation that may result in film fog.

Though the term ‘herring bone pattern’ is widely used, many of the new film packets do not display this pattern on the lead foil, rather the tyre mark (Figure 5A) or knurled pattern (Figure 5B) are common.

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Tags: Textbook of Oral Medicine Oral Diagnosis and Oral Radiology

Jan 12, 2015 | Posted by mrzezo in Oral and Maxillofacial Radiology | Comments Off

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