Ch 16 and 17 Flashcards
aqueous humor, iris, cornea and lens do what for the eye
gather light
what does retina do for the eye
converts light to nerve impulses
what does the optic nerve do for the eye
transmits nerve impulses to the brain
what focuses the light for the eye
cornea
scotopic vision
nightvision - rods
photopic vision
daylight - cones
what is sensitive to low light and cannot function in bright light
rods
what is sensitive to bright light and is responsible for color blindness
cones (no cones, no color)
what is responsible for the visibility of greyscale
cones
what is the term of whats created whenever the eye perceives a boundary
mach effect
whenever a boundary appears more distinct than it really is
mach effect
occurs when intensely bright light floods the eye directly
veil glare
what is the art of radiography
positioning
what is the science of radiography
physics
what is radiography missing whenever it comes to an xray being 2d vs 3d
depth
how does a tech compensate for the lack of depth in an xray
take two xrays of the part - them being at 90 degree angles of the other
reduction in total number of xray photons remaining in the beam
attenuation
number of photons stuck in the pt
absorption
more attenuation means what in terms of reduction in the beam
more reduction
less attenuation means what in terms of reduction in the beam
less reduction
air has a higher atomic number than fat so why does it attenuate the beam more
fat is denser
What is the order of attenuation of substances in the body - least to greatest
air
fat
water
muscle
bone
if the density is lower what does that mean for IR exposure
exposure increases since photons can easily pass through
is fat or muscle more dense
muscle
greatest tissue density in the body
bone
if density is high what does it mean for IR exposure
exposure decreases since photons get absorbed
high contrast is made from low or high kvp
low
low contrast is made from high or low kvp
high
high contrast has what kinds of colors
whites and blacks
low contrast has what kinds of colors
many shades of greys
examples of distortion
foreshortening
elongation
magnification
the closer the object is to the image receptor, what happens to the detail of the image
better detail
misrepresentation of the size or shape of a structure of interest
subject distortion
medical science concerned with all aspects of disease, including the structural and functional changes caused by disease process
pathology
diseases that are harder to penetrate are what
additives
diseases that are easier to penetrate
destructives
do additives or destructives require an increase in technical factor
additives
do additives or destructives require an decrease in technical factor
destructives
a disease that causes the body tissue to increase in thickness, atomic number, and tissue density therefore a greater attenuation of the beam will exist
additives
diseases that cause the body tissue to decrease in thickness, atomic number, and tissue density therefore less attenuation of the beam will exist
destructives
if there is an additive disease and you dont increase the technique what will happen
the image will be too light
if there is a destructive disease and you dont decrease the technique what will happen
the image will be too dark
what do you increase for additive conditions and by how much
KVp
5%-15%
what do you decrease for destructive conditions and by how much
mas
25%-50%
an encapsulated infection increasing the tissue thickness and may alter composition, particularly in the lungs
abcess
a collapse of the lung resulting in airlessness of all or part of the lung tissue. tissue density increases.
Atelectasis - additive
fibrotic changes in the liver causing it to enlarge and ascites can result. normally caused by excessive alcohol intake - increase in liver thickness, sometimes whole abdomen thickens
Cirrhosis - additive
an increase occurring in bone cell activity, leading to new bone growth - increase bone thickness
Paget’s Disease - additive
a generalized wasting away of the body tissue -reduced thickness of the body
Emaciation - destructive
free air in the pleural cavity displacing normal lung tissue and resulting in decreased density within the thoracic cavity
Pneumothorax - destructive
obstruction in the bowel causes an abnormal amount of air and fluid to accumulate - overall density of the tissue decreases due to build up of air
Bowel Obstruction - destructive
during the chronic stages of the metabolic condition, areas of the bone destruction result in punched out lesions that reduce bone composition
gout - destructive
a bone infection that causes loss of bone tissue - decreases bone thickness and composition
Active osteomyelitis - destructive
defect in the bone production due to the failure of osteoblasts to lay down bone matrix - decreased bone density
Osteoporosis - destructive
when the pleural cavity fills with either blood or fluid causing lung tissue to be displaced - increases tissue density
Pleural Effusions - additive
overdistention of the lung tissues by air resulting in lung tissue density to decrease (lung walls thin out and weaken)
Emphysema - destructive
a increase in lung tissue density caused by COVID
COVID Lung - additive
a malignant tumor from plasma cells of bone marrow and causes punched out osteolytic areas on the bone - reduces bone composition
Multiple Myeloma - destructive
a chronic inflammatory lung disease that causes obstructed airflow from the lungs
COPD (chronic obstructive pulmonary disease) - additive
when the heart is in failure, the cardiac output is diminished - causes an increase in congestion in the lungs, increasing density
CHF (congestive heart failure) - additive
