chapter 14 vision and perception

(photopic vision)cones contain ___________of ___________ light sensitive pigments

1 of 3

Cone cells require how many photons?

100

At least ______images, 90 degrees to one another is needed to view all 3 dimensions

2

(boundary effect)if objects are close together, only approximately _____% difference needed

2%

(boundary effect) if objects are far apart, differnce of greater than __________% needed

20%

The human body is ____________dimension and a x-ray is ____________dimension

3,2

(viewing distance) Blind spot at ___________viewing distance

9 inches

What are the 3 views to perceive depth

Anterior to posterior medial to lateral superior to inferior

What is known to compress gray scale, and make boundaries more distinct?

Edge enhancement

The_____________occurs when the eye perceived a boundary change (change in density)

Mach effect

What corneal malformations are caused by incoming light not properly focusing on retina?

Myopia, hyperopia, and presbyopia (visual correction)

(mach effect) change in radiographic densities changes __________________from________________.

Neurological impulses from retina

What can a radiographer do to help radiologist with perceptual difficulties?

Radiographers MUST become aware Radiographers can produce patterns to help radiologist make diagnosis

specialized Retina cells that transform light to nervous signals are:

Rods and cones

an intense light from the view box floods the eye directly, causing bright light to scatter inside the eyes (Compton effect) is known as?

Veil glare (decreases contrast perception)

Results change when viewing distance varies (inverse square law)

Viewing distance

(photopic vision)rods cannot distinguish _________________, but most sensitive to _____________light

Wavelength, green

Due to difficulty perceiving contrast difference that are far apart is known as:

boundary effect

(photopic vision) cones require _________ _____________to function

bright light

(scotopic) rods cannot function in __________________

bright light

cones detect changes in _______________, improves contrast perception

brightness

The human eyes are anatomically designed to

catches light, transforms it to nervous signal and transmits it to the brain for processing

(photopic vision) rods cannot perceive __________ in low light

colors

poor peripheral vision due to lack of ____________in the rest of the retina

cones

Radiologist need information present in what manner

consistent (routine)

(eye motion)Moving eyes while viewing an image improves ______________ ________________.

contrast perception

(photopic) cones permits greater __________ _________________

contrast perception

(inefficency of process) more x-ray photons used in ______________image compared to number of ________________photons sticking retina to view image

creating , light

Misperceptions can be ____________________in radiography

dangerous

(photopic vision) cones permit greater ___________ _____________ _______________.

density difference recognition

cones are primarily located within the __________________

fovea centralis

The function of the: aqueous humor, cornea, iris, and lens (CILA)

gather and focus light

farsighted is known as what malformation?

hyperopia

in regards to vision the brain is responsible for ______________

image perception

Large discrepancy between number of x-ray photons and number of light photons is known as:

inefficiency of process

nearsighted is known as what malformation?

myopia

Optic nerves transmit ____________________to the brain.

nervous signals (impulses)

(mach effect) Some situations prevent _______________________ from being transmitted by the retina ---- specifically(namely) bright light

neurological impulses

Rod and cone cells emit__________________ when stimulated by light

neurological impulses (signals)

(scopic) rods can generate ________________________ when struck by as few as _____light photons

neurological impulses 15

Threshold detection must minimize _____________to increase detection

noise

Moving eyes minimizes __________ ____________

optimal saturation

Perception of combinations that can be classified together to make a diagnosis

pattern recognition

Dim objects are best viewed ___________________

peripherally

Eliminate ____________ideas about images to overcome _____________.

preconceived misperceptions

difficulty focusing on close objects

presbyopia

Rods cover the rest of the ______________

retina

Bleached out by high light levels "visual purple" is known as

rhodopsin

There are more ___________than______________

rods than cones

Photosensitive cells of the retina reach _______________point quickly

saturation

what term is used to describe: night vision, sensitive to low light levels

scotopic (rod)

high concentration of cones at fovea centralis results in ______________ daylight vision

sharp

Rods are not as concentrated because they are _______________over a much greater area than _____________

spread, cones

Visual phenomenon associated with viewing extremely small object is known as:

threshold detection

what is dependent on RESOLVING POWER of total imaging system?

threshold detection

conversion and processing problems:

unsure if caused from light-sensitive cells or trouble with neurological processing