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181 Cards in this Set

  • Front
  • Back
What type of interaction causes unwanted density known as fog?
Compton interaction
The ________ is the portion of the x-ray tube that contains the filament which is the source of electrons for x-ray production
Cathode
The positive side of the x-ray tube where x-rays and heat are produced is the?
Anode
What is the name of the exact area on the anode that is struck by the electron beam?
Focal spot
What is the name of the device in a rotating anode x-ray tube that turns the rotor?
Stator
Effective use of the anode heel effect would involve positioning which portion of the part under the cathode
the tickest portion of the part under the cathode
_______ is the boiling off of electrons from the filament when current is applied
Thermionic emission
_________ is the loss of some energy from the x-ray beam as it passes through the tissue being imaged
attenuation
When the x-ray photon travels completely through the part, the activity if called what?
Trasmission
________ results in the process of image formation, whereby the beam interacts with the anatomic tissue and a portion of the beam strikes the image receptor
Differential absorption
When the x-ray photon strikes an atom within the tissue being imaged and loses all of it's energy to an inner shell electron of that atom, the photon is said to have been _________ and undergone the _________
Absorbed

Photoelectric effect
When the x-ray photon strikes an atom within the tissue being imaged, loses only part of it's energy to an outer shell electron of that atom and them continues with less energy and in a different direction than the original path, the photon is said to have been _______ and has undergone the __________
scattered

Compton effect
The x-ray beam that leaves the patient in the direction of the image receptor is often referred to as?
exit radiation
Remnant radiation is composed of?
transmitted radiation
scattered radiation
imaging of the movement of internal structures is known as?
flouroscopy
This is the measurement of the overall blackening on the radiographic image
Density
When you must repeat a radiograph because it is too dark, whats the minimum change in mAs needed?
reduce the mAs by 50% or 1/2
How will density be affected when the SID is decreased by half?

Image will be lighter
Image will be darker
Image will be darker
Contrast allows for visualization of which of the image qualities ?
Recorded detail
the misrepresentation of the size of an image is defined as what?
magnification
The ______ grid error results when the central ray is not aligned to the middle of the focused grid
off-center
A tech uses increased OID to permit the scattered x-rays to diverge from the IR without interaction, which technique is being used?
Air-gap technique
The number of lead strips per inch in a grid is a measure of what?
grid frequency
The ______ grid error results when the central ray is not aligned to the middle of the focused grid
off-center
This type of grid offers more clean up, has very little positioning latitude, requires higher exposure increasing patient dose.
Crossed Grids
The purpose of a grid is to ___ by removing scatter from the image.

A. decrease contrast
B.Increase contrast
C. Provide a shorter scale of contrast
D. b & c
What element of the collimator is responsible for preventing off focus radiation
upper shutters
In a cassette, which layer of the intensifying screen is in contact with the film?
Protective layer
A grid is constructed with ________ strips and ________ interspace material
radiopaque, radiolucent
If a body part appears white on an image, it indicates that the x-ray was:
absorbed by the dense body part
The amount of patient dose increase required with a grid is explained by the:
GCF or bucky factor
When using a grid, with no change or compensation from a non-grid exposure _______ will result
decreased density
Which of the following influences the amount of scatter radiation striking the image receptor, but does not affect the production of scatter?

a.reduce the exposure field size
b.reduce the tissue thickness
c.increase the grid ratio
d.ask a patient with a large abomen to lie prone instead of supine
c.increase the grid ratio
What grid error will show a loss of density at the periphery (outside edges) of the image?
off-focused grid
This type of scatter occurs with the removal of an outer shell electron by ionization
Compton scatter
As grid ratio increases, the likelihood of grid cutoff ________
increases
The best contrast (high, short scale) is achieved with the use of _________ ratio grids which clean up best and/or the ________ possible kvp to reduce the production of scatter.

highest, lowest
lowest, highest
highest, lowest
What is the emission of light from a screen when stimulated by radiation?
Luminescence
rare earth phosphors are better phosphors then calcium tungstate due to their ?

a. absorption efficiency
b.detective quantum efficiency
c.conversion efficiency
d. a & c
d. a & c
This type of film is intended to be used with one or two intensifying screens.
film screen
The resolution of screens is measured with what type of units:
lp/mm

( line pairs per millimeter )
( the higher the # the better we can see the image)
What is the primary controlling factor for density?
mAs
CR/DR can compensate for under/over exposure up to the point of what?
Saturation or quatum mottle
What results when you do not have enough x-rays (photons) reaching the image?
Noise (gives you a grainy look)
kVp has a ___________ relationship to penetrability.
Direct
______ and _______ absorb the most x-rays and show up white (bright) on an image.
Bone, muscle
Low density in the body has ______ density on an image.
High
According to the 15% rule, if you increase kVp by 15%, you must ______ the mAs.
half (decrease by 50%)
According to the 15% rule, if you decrease kVp by 15% you must ______ the mAs
double
Window level controls ______.
Brightness
Window width controls _______
Contrast
What is used to assess film screen contact
Wire mesh test tool
What is achieved when the color of light emitted by an intensifying screen matches the color of light a film responds to?
Spectral matching
Increase of _______ will reduce the noise of quantum mottle.
mAs
Whats the primary controlling factor for density
mAs
A wide window width has _______ contrast.
Low
A narrow window width has _______ contrast
High
The level of visibilty of small objects having similar densities or shades of grays is _____.
Contrast Resolution
The range of exposure intensities an IR can accurately detect is ____.
Dynamic Range
When you have all the data that you can window until you find what you need is called ________.
Linear Response Function
What are the advantages of fixed kVp charts?
-Easy use
-More consistent
-Greater assurance of penetration
-Uniform contrast
-less PT dose
-Better for equipment
What are the disadvantages of a fixed kVp chart?
-increased scatter
-lower contrast
What are some advantages of a variable kVp chart?
-easy use
-small incremental changes
What are some disadvantages of variable kVp charts?
-higher contrast
-adequate penetration might not be achieved
-have to accurately measure the body part
What gives radiographers guidelines to select standard techniques during an exam?
Exposure technique charts
What is a measurement of the amount of light transmitted through the film?
Optical density
If you decrease the SID andy ou do NOT change the technique what will happen to the optical density?
It will increase causing the image to be darker
According to the ______ the intensity of the x-ray beam is proportional to the square of the distance from the source.
Inverse Square Law
The distinctness of structural lines recorded in the radiographic image is called ____.
Sharpness of recorded detail
The smallest detail that can be detected on an image is called ____. This is really good with DR.
Spatial resolution
kVp is considered the controlling factor for radiographic __________
contrast
A radiograph with few densities but but great differences among them is said to have ______ contrast
High contrast (short scale contrast)
A radiograph with a large number of densities but little differences among them is said to have ______ contrast
low contrast ( long scale contrast)
Photographic properties of the recorded image and determined by the extent to which the structural components of the anatomic area of interest can be seen. (Anything that has to do with density & contrast) is called _____.
Visibility of recorded detail
The longer the SID gives you ____ recorded detail and ____ magnification.
Better, decreased
What type of distortion will we use to our benefit in imaging?
elongation
Images in F/S are stored in the ____ layer.
Emulsion
Where are the images stored in CR?
Photostimuble phosphor plate
If the intensifying screen glows after the x-rays have stopped it is called ____.
Phosphorescence/Screen lag
What is grid oscillation?
When the grid moves during exposure to blur the grid lines.
What is total filtration made up of?
Added filtration and inherant filtration
When using backup time we use _____% more mAs then what we anticipate to prevent overexposure to the patient.
150%
What is a graphic representation of where the shades of gray will be on an image?
Histogram
This provides a method of altering the image to change the display of the digital image. Matches the contrast & brightness to the mathmatical formula that is programmed for that body part.
Look up table
The computer language in medicine is called ____.
DICOM (Digital imaging and communication in medicine)
Patient information language is called ____.
HL7 (health level 7)
You do not want to use the minimum response time for what type of patients?
pediatrics, geriatrics, or uncooperative patients
Pneumonia is a(n) _____ type of pathology to a chest image.
additive
Emphysema is a(n) ____ type of pathology a chest image.
destructive
Ascites is a(n) _____ type of pathology to the abdomen image.
additive
Air is a(n)____ type of pathology to the abdomen image.
destructive
What does APR stand for?
anatomically programmed radiography
When using film-screen, what happens when outside detectors are selected for an AP thoracic spine?
The spine will have insufficient density
Changing the kilovoltage peak by ______ will have the same effect on radiographic density as doubling the mAs, or reducing the mAs by 50%
15%
What happens if an AEC is activated for the table bucky but the upright bucky is being used?
back-up time is reached resulting in high exposure to the patient and IR
What describes the shortest exposure time required for the AEC device to operate
minimum response time
AEC devices work by measuring radiation that is transmitted through the ______
patient
When using AEC with film screen examinations how can the radiographer adjust the density?
Using the density control
simplest type of beam restricting device constructed of a flat piece of lead that has a hole in it.
aperature diaphragm
This is the high end of overexposure.
saturation
KVP is which of the following

a. energy
b. quality
c. penetrability
d. all of the above
d. all of the above
This occurs when a projectile electron completely avoids the orbital electrons of the tungsten atom and travels very close to it's nucleus
Bremmsstrahlung interactions
The product of both flux gain and minification gain
Brightness gain
This is comprised of a filament and a focusing cup
Cathode
This describes that similar anatomic parts can use similar exposure techniques to achieve diagnostic radiographs
comparative anatomy
This refers to the area on the anode target that is exposed to electrons from the tube current.
Actual focal spot size
This refers to the focal spot size as measured directly under the anode target
effective focal spot size
This describes how the x-ray beam has greater intensity on the cathode side of the tube, with the intensity diminishing toward the anode side.
anode heel affect
Which x-ray tube component serves as a source of electrons for x-ray production
filament
Electrons interact with the ____ to produce x-ray and heat
target
the cloud of electrons that forms before x-ray production is referred to as
space charge
The intensity of the x-ray beam is great on the :
cathode side
According to the line focus principle, as the target angle decreases, what happens to the effective focal spot size?
it decreases
Which type of target interaction is responsible for the majority of the x-rays in the diagnostic beam
bremmsstrahlung
The ability of an x-ray photon to remove an atoms electron is a characteristic known as
ionization
The x-ray interaction responsible for absorption is
photoelectric
The x-ray interaction responsible for scattering is
compton
Electrons flow from _______ to ______
cathode to anode
tube current is measured in ______
milliamperes
As electrons strike the anode target about ______ % of their kinetic energy is converted to heat, whereas only _____ % of their energy is converted to x-rays.
99 % is heat , 1 % is x-rays
brightness gain is created on the ______ phosphor
output
If you are given 200 mA and an exposure time of 1/40 calculate the mAs.
1/40 = 0.025

200 x 0.025 = 5

Answer 5 mAs
Given mA= 400 and mAs= 80 calculate the exposure time.
80 / 400 = .2

Answer .2 seconds
Whats the density maintenance formula?
mAs1 D1^2
--------- = -------
mAs2 D2^2
Whats the inverse square law formula
I 1 D2^2
-------- = ----------
I 2 D1^2
A _____ change in mAs or a ____ change in kVp is necessary for a visible difference in density on a radiograph.
A 30 % change in mAs or a 15% change in kVp is necessary for a visible difference in density on a radiograph.
The density on a radiograph will be equal for any combination of mA and time, as long as the final product of mAs stays the same according to:
the Reciprocity Law
To maintain a certain density, if you increase the kVp by 15% you must divide the original mAs by ____
2
How would you decrease 80 kVp by 15%
80 x 0.85 = 68 kvp
How would you increase 80 kVp by 15%
80 x 1.15 = 92 kVp
To maintain a certain density when decreasing kVp by 15% multiply the original mAs by ______
2
The function of contrast is to make _______ visible
recorded detail
You get high contrast by using ______ kvp
low
high contrast = _____ scale
short
high contrast / short scale is primarily used for ______ body parts
extremities (bones)
If you are doing a chest and using 110 kvp, and than you want to see the ribs how would you adjust the kVp?
Use less kvp so it doesn't penetrate the ribs and you get white on your image = photoelectric effect (absorption)
Which type of tissue is going to easily absorb x-rays and why?
muscle, because it's dense
(molecules are packed tightly together)
Low density in the body = ____ density on the image receptor
high density
Is kVp for CR/DR controlling contrast?
NOOO.. the computer controls the contrast ( or allows us to control it)
Whats is the purpose of kVp when dealing with CR/DR since the computer controls contrast?
penetrability
kVp is a secondary contributing factor to _______
quantity
Visible change for kvp is _____ %
Visible change for mAs is ______ %
5 % for kvp
30% for mAs
Wider width = ______ greys
Narrow width = ______ greys
wider width = less greys
narrow width = more greys
more greys =more latitude which makes for more ________ ________
dynamic range
preferred technique is ___ kvp and ____ mAs
preferred technique is high kvp, low mAs
If going from a 72 inch distance to a 40 inch distance what happens to density
it increases
Contrast resolution is a selling point for which of the following

Film screen
DR
CR
CR & DR
DR & CR

( with CR & DR spatial resolution is not good)
smallest thing that can be seen is:
spatial resolution
Sharpness of detail is what type of property
geometric property
A long SID gives the best ________
recorded detail
long SID cuts down on what?
magnification
Is a short or long OID preferable
Short
short OID improves _______ which improves _______
short OID improves magnification which improves recorded detail
What type of focal spot size is best for the best sharpness and recorded detail
Small focal spot size
What two terms go along with shape distortion
elongation and foreshortening
Which type of shape distortion can be used to your advantage
elongation

( calcaneus projection)
________ is critical in order to avoid shape distortion
alignment
in order to reduce the amount of heat being used what size focal spot should a tech use?
A larger focal spot
Why does the anode spin?
the dissipate the heat
Electrons are + or -
negative
Whats within the focusing cup that produces electrons
filament
Whats the filament made out of?
tungsten ( high atomic #, can handle a lot of heat )
Whats the charge on the focusing cup?
negative
Electrons travel at:
the speed of light
increasing time of exposure allows the electrons to:
flow from cathode to anode a longer period of time.
Why does a tube have housing ?
to protect from leakage and electrical shock
When were x-rays discovered?
November 8 1895
Where is the image on film
emulsion layer
Where is the image in CR
photostimuable phosphur plate
where is the image with DR
on the computer screen
Whats the intensifying screen made of?
rare phosphor
What is it called when a intensifying screen continues to give off light when it shouldn't (it keeps glowing)
phosphorescence (bad)
(after)
screens are considered radiation protection devices because?
they allow you to use less radiation
what is a small discrete bundle of energy
quantum or photon
the faster the screen system the more ______ emitted.
light
_______ permits x-rays to penetrate, _______ does not allow x-rays to penetrate
radiolucent permits x-ray penetration
radiopaque does not allow x-ray penetration
When x-rays spread out it's called?
divergence
filtration decreases patient dose because it removes the _________
lower energy x-rays
outer shell electron is:
compton
inner shell electron is:
photoelectric
thinning out the beam is:
attenuation