image processing
as the amount of beam filtration is increased
a. contrast increase
b. there is no effect on contrast
c. contrast decrease
d. contrast increases because the beam is harder
C
overall wavelength of the beam is shorter resulting in lower contrast.
the increase in average photon energy when using three phase 12 pulse equipment compared with single phase equipment is
a. 1.35%
b. 41 %
c. 1.41 %
d. 35 %
B. this is why the formula for calculating heat units for three phase, 12 pulse equipment is multiplied by 1.41
the variation of x ray intensity along the longitudinal axis of the x ray beam describes
a. beam collimation
b. positive beam limitation
c. anode heel effect
d. x ray emission spectrum
C
the intensity of the x ray beam is actually a little higher toward the cathode side of the tube.
the adjustment in technical factors required when using beam restriction is
a. increase kvp
b decrease kvp to reduce the number of compton interactions taking place
c. decrease mas to reduce the number of compton interactions taking place
d. increase mas to compensate for the number of rays removed from the primary beam
D
rays that have been removed from the beam must be restored by increasing mAs. the area being irradiated still remains smaller
what effect does beam restriction have on contrast?
a. decreases contrast by focusing the x-ray beam
b. decrease contrast because of higher kvp level used
c. increases contrast by focusing the x ray beam
d. increase contrast because of reduction in the number of Compton interaction that occur
D
compton interactions produce scatter which causes contrast to decrease
the function of contrast is to:
a. make the image appear sharper
b. compensate for uneven anatomical structures
c. brighten the image
d. make detail visible
d.
without contrast produced by differential absorption of the x ray beam detail cannot be visible.
the stream of electrons in an x ray tube is focused by the
a. line focus principle
b. potential difference
c. molybdenum collar around the filament
d. tilted target
the molybdenum collar around the filament carries a negative charge and prevents electrons from scattering backward by repelling them.
magnification is caused by
1. short SID
2. long SID
3. short OID
4. long OID
a.2,3
b.1,4
c.1,3
d. 1 only
B
the optimum conditions are longer SID and shorter OID
which exposure factor cause excessive image noise if set too high?
a. kvp
b. mas
c. AEC
d. Time
a.
extremely high kvp is used with low mAs resulting in too few x ray photons making the image this will cause noise or mottling of the image.
which of the following affects radiographic density?
a. atomic mass of the x ray tube anode
b. x ray tube angle
c. atomic number of the cathode filament
B
due to a change in SID resulting from the tube angle
poorer recorded detail may be caused by which of the following factors?
a. shorter OID
b. long SID
c. small focal spot
d. pixel pitch wide
D
this is the space from center to center of adjacent pixels.
what device may be used to ensure consistency of radiographic quality from on e exposure to the next?
a. electronic timer
b. step up transformer
c. automatic exposure control
d. high frequency generator
C
the AEC is calibrated to provide the images most preferred by the radiologists
an artificial increase in display contrast at an edge of the image is
a. smoothing
b. edge enhancement
c. contrast resolution
d. spatial resolution
B
enhances visibility of detail.
image artifacts are usually classified as
a. scatter
b. plus density and minus density
c. compton and photoelectric
d. patient motion and equipment motion
b
unwanted light or dark areas on an image
when a quality control test is performed to ensure that penetrating ability of the x ray beam is accurate the result must be within what amount of the control panel setting?
a. 2% pf SID
b. 4%
c. 10%
d. 4
D
kvp must be within plus or minus 4 of what is set
high kvp prduces which of the following?
1. high contrast
2. few gray tones
3. long scale contrast
4. short scale contrast
5. low contrast
6. many gray tones
a.124
b. 356
c. 5
d. 1
B
shorter wavelength beam more uniformly penetrates the various anatomic structures
what regulates the duration of x ray production?
a. step down transformer
b. rectifier
c. cathode
d. timer
D
most equipment uses an electronic timer
recorded detail
a. photographic representation of the part being radiographed
b. controlled by kvp
c. controlled by mAs
d. geometric representation of the part being radiographed
D
controlled by SID OID and focal spot size
distortion may be described as:
a. misrepresentation of an anatomical structure on film
b. foreshortening
c. elongation
d. magnification
a. misrepresentation of an anatomical structure on film
bcd are examples of distortion.
the amount of darkness on a radiograph is best described as
a. contrast
b. detail
c. brightness
d. mAs
D
the technique has the highest mAs and the highest kvp
what effect does the use of radiographic grids have on contrast?
a. decrease contrast
b. increase contrast
c. no effect on contrast
d. increase contrast by absorbing scatter radiation
D
many of the scatter photons are being absorbed by the grid resulting in higher contrast.
which of the following measures the tube current?
a. anode
b. mA meter
c. ionization chamber
d. falling load generator
B
current is the flow of electrons as measured in mA. (mili amperes) mA meter provides the reading.
when AEC is used increasing the Kvp
a. increases density proportionately
b. increases radiographic contrast
c. increase exposure time
d. has no effect on density
D
automatic exposure controls are set to terminate the exposure after certain amount of radiation has passed through the ionization chamber. consequently changes in kvp will have no effect on density.
as kvp is increased
a. density decrease
b. contrast increase
c. recorded detail increase
d. contrast decrease
C
focal spot size controls recorded detail not density
to ensure consistency of radiographic quality from on e exposure to the next what device may be used?
a. electronic timer
b. automatic collimation
c. automatic exposure control
d. falling load generator
C
automatic exposure control usually an ionization chamber is the only choice that has to do with consistency of radiographic quality.