Vision And Perception in Radiography

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*Visual misrepresentations

-Can be dangerous in
clinical radiography

*Avoid preconceived ideas
-Mental erasing of
opinions to permit high-quality viewing of radiographic images
-Experience d technologists produce images to maximise diagnostic process

*Visual anatomy

–    The human eye is designed to ‘gather’, ‘focus’, ‘convert’, and ‘transmit’
* Visual physiology
–     0.2 seconds to acquire information; ‘staring’ at an item does not improve visual quality
*Rod and Cone Cells
–     Contain photosensitive pigments that respond to light
*Photopic (daylight) vision
–     Cones allow greater visual acuity and contrast perception
*Scotopic (night) vision
–     Entirely peripheral and therefore difficult to focus
*Inefficiency of the medical imaging process
–      1 out of 100,000 photons
contribute to impulses
received by the brain
*Threshold detection

–       Perception of extremely
small or faint details
*Boundary effect
–       Visual system and their ability to perceive contrast differences
–        25-33% change to be visible

*Mach effect
–  Occurs when the eye perceives a boundary
–  Edge enhancement makes the boundary more distinct than it really is
*Eye motion
–  A scanning motion increases contrast perception
*Veil glare
–  When intensely bright light floods the eye directly
*Viewing distance
–  Changes the intensity of the light (ISL) and the
angle of the incident light photons
*Pattern Recognition
–  Comparing mental images of patterns
(anatomical, physiological, etc) to provide a
diagnostic opinion

*Thinking three-dimensionally
–  View images from a 3D perspective
–  “Radiographic positioning requires a solid
knowledge of the shape and location of skeletal
and soft tissue structures…”
–  Develop the ability to mentally visualize the
change of overlapping structures

*Artistic radiography
*MVA situation requires adaptations to conventional positioning
* Non-destructive testing
–   Assessment of materials
i.e. castings and welds
* Biological research
–   I.e. study of birds and bats in flight

* Veterinary radiography
* Forensic radiography
* Art restoration
* Archaeological radiography


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