factors affecting the radiographic image and film faults l.
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Factors affecting the radiographic image and film faults. . Image quality. I. Contrast II. Image geometry III. Characteristics of the X-ray beam. I. Contrast. Subject contrast Film contrast Fog and scatter. Subject contrast. Differences in tissue thickness

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Presentation Transcript
image quality
Image quality

I. Contrast

II. Image geometry

III. Characteristics of the X-ray beam

i contrast
I. Contrast
  • Subject contrast
  • Film contrast
  • Fog and scatter
subject contrast
Subject contrast
  • Differences in tissue thickness
  • Differences in tissue density
  • kV or penetrating power of the radiation beam
film contrast
Film contrast
  • The characteristic curve of the film
  • Optical density
  • Type of film- direct or indirect action
  • Processing
fog and scatter
Fog and scatter

Fogged film

Scatter radiation from within the patient’s

tissues

perception of the radiographic image
Perception of the radiographic image
  • Partial images-we all see the same partial images but we don’t necessarily perceive the same object
  • Contrast
  • Context
image geometry
Image geometry
  • Positioning of the film, object and x-ray beam
  • Focal spot size and principle of line focus
  • Focal spot-object distance (FSOD), object-

to film-distance (OFD)

focal spot size heat distribution and image sharpness
Focal spot size, heat distribution and image sharpness
  • Focal spot 1mm
  • Heat needs to be distributed over as large

as possible area

  • Principle of line focus
slide18
FSFD
  • Increasing the distance between the focal

spot and the object results in an image

with increased sharpness and less

magnification of the object

slide20

Decreasing the distance between the

object and the film increases the

sharpness and result in less magnification

of the object

practical factors influencing image quality
Practical factors influencing image quality
  • The X-ray equipment
  • The image receptor/screen combination
  • Processing
  • The patient
  • The operator and radiographic technique
typical film faults
Typical film faults
  • Film too dark
  • Overexposure

Overdevelopment

Fogging

Thin patients tissues

films with inadequate contrast
Films with inadequate contrast
  • Processing errors
  • Exposure errors
image unsharp and blurred
Image unsharp and blurred
  • Movement of the patient during the exposure
  • Excessive bending of the film during the exposure
  • Poor film/screen contact within the cassette
film marked
Film marked
  • Film packet bent by the operator
  • Careless handling of the film in the darkroom :
  • Finger prints
  • Finger nails
  • Bending
  • Static electricity
operator positioning faults
Operator positioning faults
  • 1.Incorrect placement of the film packet
  • Back to front, image of the lead foil evident
  • ( film also too pale)
  • Inadvertently used twice, double exposure
  • (films also too dark)
  • Not covering the area of interest