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RTE 1418C Final Exam Graded A+
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RTE 1418C Final Exam Graded A+
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RTE 1418C Final Exam Graded A+___ is the phenomenon that occurs around the filament during thermionic emission and
prevents the further escape of electrons from the filament. - ANSWER-space charge
effect
___________ imaging is accomplished with fluoroscopy as opposed to radiography. -
ANSWER-dynamic
_____________ envelopes are more commonly used in today's x-ray tubes. -
ANSWER-metal
________________ is done during preprocessing to correct for an irregular pattern over
the image. - ANSWER-flatfielding
(T/F) Digital systems are less sensitive to scatter radiation than film/screen systems. -
ANSWER-False
(T/F) Dynamic range is the ability of a digital imaging system to respond to varying
levels of exposure - ANSWER-True
(T/F) Most CMOS detectors use both N-type and P-type transistors to form the
electrically controlled gate - ANSWER-true
(T/F) Spatial resolution in digital imaging is dependent on pixel size - ANSWER-true
(T/F): Aliasing occurs when the sampling frequency is not greater than twice the
frequency of the input signal - ANSWER-false
(T/F): The look-up table that is used to determine the brightness and contrast of an
image is unique for each anatomic part - ANSWER-true
(T/F): The Nyquist theorem states that the sampling frequency must be less than twice
the frequency of the input signal - ANSWER-false; more than twice
A 10-bit depth can display how many shades of gray? - ANSWER-1024
A charge-coupled device does all of the following EXCEPT:
a. reduce the size of the projected light image
b. transfer the image to a capacitor
c. convert light into x-ray photons
d. act as receptors via lenses or fiber optics - ANSWER-c. convert light into x-ray
photons
A direct relationship exists between image brightness and - ANSWER-window level
,A disadvantage of using magnification mode during fluoroscopy is - ANSWER-the
patient receives additional dose
A filament electron removes a K shell electron and an M shell electron fills the vacancy.
The K shell binding energy is 69.5 keV and the M shell binding energy is 2.8 keV. What
is the energy of the K-characteristic photon produced? - ANSWER-66.7 keV
A fluoroscopic feature that automatically turns the x-ray beam on and off rapidly during
operations is known as: - ANSWER-pulsed fluoroscopy
A ghost image can occur in digital imaging because of ____________________. -
ANSWER-incomplete erasure
A high-speed electron entering the tungsten target is attracted to the positive nucleus of
a tungsten atom and, in the process, is decelerated. This results in - ANSWER-brems
A larger bit depth: - ANSWER-increases contrast resolution
A light-sensitive semiconducting device that generates an electrical charge when
stimulated by light and stores this charge in a capacitor is the - ANSWER-CCD
A quality radiograph is done using 10 mAs, 70 kVp, and a 12:1 ratio grid. How much
mAs is needed to produce an image with the same exposure to the IR when the grid is
removed? - ANSWER-2 mAs
A radiographic image that has brightness levels that are very similar to each other -
ANSWER-has low contrast and has long-scale contrast
A rheostatic will - ANSWER-vary resistance
A shorter wavelength photon is associated with - ANSWER-higher frequency, higher
energy, increased ionizing potential
A signal is received by the monitor from which part of the TV camera tube? - ANSWER-
electron gun
A solid chemical element or compound doped with impurities that make it highly
conductive is known as a - ANSWER-semiconductor
A step-up transformer changes voltage and amperage in the following way: - ANSWER-
Voltage is increased, and amperage is decreased proportionally
A step-up transformer has - ANSWER-more secondary coils than primary coils.
,A system that used scintillators that convert X-rays to light, light to electric charge, and
store the charge in capacitors is known as - ANSWER-CMOS
A technique chart should be prepared for each AEC x-ray unit and should contain which
of the following information for each type of examination?
Photocell(s) used
Optimum kilovoltage
Backup time - ANSWER-Photocell(s) used
Optimum kilovoltage
Backup time
A wider (increased) window width (select the two that apply) - ANSWER-increases
range of densities; decreases contrast
Added filtration will ______ beam quality and ______ beam quantity. - ANSWER-
increase; decrease
Adjusting the rheostat changes the _______________ in the ______________ circuit. -
ANSWER-resistance; filament
AEC controls the amount of radiation reaching the IR by controlling the - ANSWER-time
of exposure
AEC devices work by measuring - ANSWER-radiation that exits the patient
After a photoelectric interaction, the incident photon - ANSWER-loses all of its energy
and no longer exists
All other factors remaining the same, if a 14 × 17 in. field is collimated to a 4-in.-square
field, the radiographic image will demonstrate - ANSWER-less receptor exposure
All the following are related to spatial resolution except - ANSWER-scattered radiation
Also called lateral decentering, the _____ grid error results when the central ray is not
aligned to the middle of a focused grid. - ANSWER-off-center
Although coherent scattering is most likely to occur ____________, some of this
unmodified scattering occurs throughout the diagnostic range and may result in small
amounts of radiographic fog. - ANSWER-at less than 10 keV
Amorphous selenium is used as the - ANSWER-photoconductor for direct capture DR
imaging
Amorphous silicon is used as the - ANSWER-photodetector for indirect capture DR
imaging
, An advantage of the variable kVp technique chart is that it: - ANSWER-makes smaller
technique changes possible
An example of a scintillator used in an indirect conversion detector is
1. cesium iodide.
2. gadolinium oxysulfide.
3. amorphous selenium. - ANSWER-cesium iodide & gadolinium oxysulfide
An incident x-ray interacts with an atom without ionization during - ANSWER-coherent
scattering
An increase in kVp would ________ the ______________ of the emission spectrum -
ANSWER-increase; both amplitude and position
An increase in mAs would _________ the ______________ of the emission spectrum. -
ANSWER-increase; amplitude alone
An increased part thickness results in: - ANSWER-increased beam attenuation.
An optimal AP abdomen radiograph can be produced using 40 mAs, 75 kVp, and a 12:1
grid. How much mAs would be needed if the only grid available is a 6:1 ratio grid? -
ANSWER-24 mAs
An x-ray tube is an example of current flow in - ANSWER-a vacuum
An x-ray tube with two filaments is called a - ANSWER-dual focus tube
As a wave's wavelength increases, its frequency - ANSWER-decreases
As beam restriction increases, the quantity of scatter radiation __________ and
radiographic contrast ___________. - ANSWER-decreases; increases
As compared to digital imaging, film-screen imaging has: - ANSWER-a narrower
dynamic range
As electrons impinge on the target surface, less than 1% of their kinetic energy is
changed to - ANSWER-x-rays
As kVp ___________, the probability of photoelectric absorption ______________. -
ANSWER-increases; decreases
As mAs is increased the signal-to-noise ratio is ____________. - ANSWER-increased
As the anode angle decreases, - ANSWER-image sharpness improves
the effective focal spot is smaller than the actual focal spot
the anode heel effect is emphasized
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