CH 16 VISION & PERCEPTION

photopic vision contains _____ out of _____ light sensitive pigments

1, 3

scotopic vision can generate neurologic impulse when struck by as few as ______ light photons

15

if objects are close together, only approximately ___% difference needed

2

orthogonal images are ___ separate images at a right angle to each other

2

single radiographic image can only display _____ of 3 dimensions

2

if objects are far apart, difference of greater than ___% needed

20

to control image in space, radiographic images are ______ displays of _______ anatomy

2D, 3D

3D to 2D must have two _______ degree oppossing views to perceive depth

90

a __________ spot is created by fovea centralis at _______ distance

blind, 9"

a ____________ effect occurs because the visual system has difficulty perceiving contrast differences that are distant from one another

boundary

______________ light is an example of a mach effect

bright

photopic vision requires _________ light to function

bright

scotopic vision cannot function in __________ light

bright

cones detect changes in _______________

brightness

scotopic vision cannot perceive ___________ in low light

colors

photopic vision is controlled by ____________

cones

poor peripheral vision due to lack of _________ in the rest of retina

cones

rods are not as concentrated as __________ and distributed over the peripheral retina

cones

photopic vision permits greater _____________ perception

contrast

visual acuity improves ___________ perception

contrast

when expected patterns are not recognized, a diagnostic "________________" can exist

conundrum

more x-ray photons used in _____________ image compared to number of light photons striking retina to ________ image

creating, view

having an understanding of __________-________________ anatomy can hep in understanding the concept of an "image in space"

cross sectional

misperceptions can be ___________ in radiography

dangerous

photopic is ___________ vision and is controlled by ___________

daylight, cones

positioning is intednded to "____-________________" anatomy

de-superimpose

veil glare _______________ contrast perception

decreases

changes in radiographic ______________ can cause a change in neural signals sent to the brain from the retina

densities

conventional radiographic images are missing ______________

depth

preshyopia = _____________

difficulty with close objects

edge enhancement makes boundary more __________

distinct

___________ _____________ is a visual illustration that can cause a misperception on image information

edge enhancement

mach effect occurs when the eye perceives an ____________ boundary

exposure

hyperopia = ______________

farsighted

cones primarily located within _________ _______________ of retina

fovea centralis

edge enhancement compresses ___________ scale

gray

photopic vision permits _________ density difference recognition

greater

regarding visual acuity, best in ___________ light conditions

high

__________ concentration of cones at fovea centralis results in _________ daylight vision

high, sharp

veil glare is reduced or eliminated by ___________ masking

image

scanning while viewing images _____________ contrast perception

improves

x-ray to light conversion for vision is extremely ___________

inefficient

radiographers position area of ___________ so image __________ will be improved

interest, quality

corrective ___________ focus light onto fovea centralis for highest ____________ acuity

lenses, visual

higher image contrast can _________ the boundary effect

lessen

aqueous humor, cornea, iris, and lens gather and focus ___________

light

rod and cone cells emit neurologic impulses when stimulated by __________

light

retina cells transform _________ to nervous impulses

light (rods and cones)

the human eye catches __________, transforms it to ____________ signal, and transmit it to ___________ for processing

light, nervous, brain

effective positioning skills include knowledge of:

location of structures, shapes of structures, relationship of structures to one antoher

scotopic vision is sensitive to ________ light levels

low

the neurologic basis for boundary effect is the _____________ effect

mach

certain structures must be _________________ to demonstrate area of interest

manipulated

myopia = ____________

nearsighted

rads ___________ image information presented in a consistent manner

need

scotopic vision = _____________ vision

night

stotopic is ____________ vision and is controlled by ___________

night, rods

___________ nerves transmit nervous signal to brain

optic

scanning minimizes ___________ saturation

optical

__________ images are taken to provide a 3-D perspective

orthogonal

comparing mental images of patterns (anatomical, physiological, historical) for diagnostic opinions is known as _____________ ____________________

pattern recognition

dim objects are best viewed _______________

peripherally

very large discrepancy between the number of emitted x-ray ____________ and the number of __________ photons that ultimately strike the retina

photons, light

regarding the mach effect, some situations _____________ neurologic impulses from being transmitted by retina

prevent

image conversion occurs in the _____________

retina

________ cover the rest of retina

rods

eye motion causes photosensitive cells of retina to reach _____________ point quickly

saturation

during veil glare, bright light _____________ inside eye

scatters

_________________________ of anatomical structures is a huge challenge for non-radiologist

superimposition

the visual phenomenon associated with viewing extremely small objects and details is known as ____________ detection

threshold

T/F there are more rods than cones

true

regarding viewing distance, light intensity __________ (inverse square law)

varies

radiologist overcome blind spots by ______________ their viewing distance to improve ____________ acuity

varying, visual

when intense light floods eyes directly, it is called _________ ___________

veil glare

data concerning threshold detection indicate that results change is called ______________ distance

viewing

regarding controlling an image in space, one should start by mentally ________________ the object floating _____________ the body

visualizing, within

scotopic vision cannot distinguish light _______________ but most sensitive to __________ light

wavelenghts, green