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51 Cards in this Set

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speed of anode during x-ray production?
3000-2500
Concerning photons's wavelength?
shorter wavelength the greater the energy
high electric potential (kVp) is applied across the x-ray tube then the electrons are________to the anode
attracted to
kilovoltage controls the______
of the electrons to cathode flowing to the anode
speed
difference in taking a x-ray with or without grid is:
non grid requires more KvP
Because of unavoidable large oject film distance when taking a lateral or oblique cervical, magnification will be most reduced by using a focal film distance (FFD) of
72 inches
reason lateral or flexion/extension c-spin do not normally require grid?
neck is typically smaller laterally
you can identify the aspect of the x-ray tube that is the anode end of the tube because
there are two main power supplying electrical cables
as demostrated on a characteristic cirve, as film contrast decreases, film latitude
increases
the fixing chemistry usually contains
Phenidone
film latitude:
meausre of the film's ability to record density and contrast over the useful range of optical denisty (OD) from .25 to 2.5
x-ray photons:
no rest mass and are neutral in charge
electron binding energy:
strength of electron attached to nucleus
x-rays are considered part of particulate ionzing radiation
true or false
false: electromagnetic radiation
x-rays identified by their energy in the measured in:
electron volts
structures that absorb x-rays are called
radioppaque
muscular person needs higher kvp or lower kvp
higher
when performing an AP thoracic view: one should place the anode where?

What is this called?
place the anode closest to the head and cathode away from patient

anode heal affect
due to thickness of the abdomen in lateral dimension, a lateral x-ray projection of the lumbar spine requires:
a moving or stationary grid
requarding full spine radiography, due to the inherent non uniformity of part thickness, the best solution to create a more uniformly exposed x-ray would require the use of
sectional filtration
fixing solution will remain in the fixing solution____ as long as the developer
200%
grids are made of alternating strips of
lead and radiulent material
what are heat units
kVp x mA x seconds
added filtration what material is used
aluminum
intensifying screens for routine radiography would result in the least x-ray exposure to the patient?
high plus
primary purpose of added filtration at the x-ray tube is to:
scatter the low energy x-rays before striking the patient
magnification can be reduced by
using shorter source/image distance
poor film/screen contact results in
a locally fuzzy image
x rays travel:
at the speed of light
the intensity of the xray beam is
greater on the side of the cathode
an x-ray machine converts what percentage of available energy into x-rays
1%
kilovoltage (kvp) controls the penetrating power of the x-ray:
photon
what happens if kVp is too high?
increased photons will cause white areas of the film to appear dark=diminished contrast

compton scatter radiaton will also be excessive=lacks contrast
kvp too low?
photons will not be able to penetrate the body=film lacks denisty and white film.

low kvp means higher MaS which means longer time of exposure=longer time.

patient absorbs more radiation
lower kVp values are used for what body types
extremities
milliamperage (mA)
describes the amount of electrical current flowing through the cathode filament during exposure.

The mA must complement the time of exposure to make adequate number of x-ray photon availabe to the film
high mA=


lower mA=
results shorter time of exposure

longer time of exposure
variable kVp
kilovoltage increases as size of body part increases and mAs values remain fixed for that body part.

problems:increasing compton interactions occurs in tissues.
Also, the scattered xray cannot be cleaned up by the grid and you get less contrast and film looks foggy
fixed kV method:
prefered method: maintains the contrast of the resulting film
prefered method for x-ray technique
fixed kV for given body part
vary mAs for each centimeter of thickness for every body part
what would you do if patient was
muscular
child or osteopenia?
normal mAs should be incrased a minimum of 50%

decrease mAs by 30%
why the x-ray beam does not exhibit uniform intensity?
due to the anode heel effect.
how to deal with the heel effect
use larger focal distance.

upright radiography make sure tube is directed toward standing patient.

have patient with thinner body part lie coser to anode
what controls contrast?
kVp and film type
what determines detail?
shortest object film distance
longest film distance
shortest exposure
film with best resolving power.
longer focal film distance causes what to happen with time
causes exposure time to be longer
best resolving film-screen combinations are
slowest and least sensitive to stimulation of the photons. (usually only for smaller extremites)
obese patient needs lateral films: identify 3 ways to improve films
1. patient compression (reduces patient exposure, reduce workload of x-ray tube)

2. mAs should be increased by 50%

3. longer focus distance: sharper image, less magnification and decreased patient dose.

using sectional filtration on lateral lumbar view uniformly expose the film from L1 to S1
which factors control contrast of a film?
kilovoltage peak (kVp)
what are 4 things that need to be considered reguarding choice of exposure time?
shortest practical time should be used
time of exposure could affect patient motion
logner times increase density
moving grids require exposure times of .1 seconds or more.
mA station controls the
electrical current passing through the filament