Species: Canine   |   Classification: Miscellaneous


  • To produce an accurate portrayal of area under examination:


  • Blurring of outline of the object under examination prevents accurate interpretation.
Geometric unsharpness
  • Also known aspenumbra effect.
  • This is dependent on:
    • Size of focal spot Radiation physics unsharpness - focal spot size.

Other factors affecting image quality

  • Contrast and unsharpness appear to be linked.
  • If there is high contrast the image appears sharper.
    Contrast and sharpness are completely independent.
  • Minimize by increasing film focal distance and reducing object film distance.
  • Occurs if:
    • Object film distance is large:
      • X-ray beam continues to diverge after being incident on object Radiation physics magnification.
    • X-ray beam oblique.


  • Occurs if object and film are not parallel Radiation physics geometric distortion.
  • Occurs in large animal radiography where cassette hand held at end of pole and difficult to retain in constant position.

Film and screen quality