The reproducibility of exposures of a radiograph unit may not vary more than ___% to be considered within acceptable limits
5 %
Leakage radiation from the x-ray tube cannot exceed _____ at distance of 1 meter
100 mR/h
when using over 70 kVp, the total filtration in the primary beam must be at least
2.5 mm Al
The field positioning light and the actual radiation field cannot vary by more than what percentage of the SID?
A. +/- 2%
B. +/- 5%
C. +/-10%
D. +/-20%
2%
which of the following reduces radiation exposure to personnel?
1. reduce time of exposure
2. increase distance from source of radiation
3. insert shielding between source of radiation and personnel
ALL THE ABOVE
which of the following laws prove that distance is the best protection against radiation?
inverse square law
which of the following characteristics makes lead such an excellent protective barrier
1. high density
2. high atomic number
3. high absorption coefficient
ALL THE ABOVE
effective quality control and quality assurance programs are required for accreditation by
TJC
The lead equivalency for a pair of protective gloves must be at least how much?
.25mm
which of the following methods is used to determine if an xray tube has adequate filtration?
half value layer measurements
which of the following are things a radiographer should do in order to avoid unnecessary patient exposure?
1. avoid retaking radiographs
2. use optimum kVp for all exposures
3. keep equipment in good working order
ALL THE ABOVE
how will beam filtration affect the primary beam?
make it more homogenous
each tube has its own radiographic rating chart to show
maximum allowed exposures
which focal spot would be selected on the console if you are performing an exam using an mA station above 300 mA?
Large focal spot
how any heat units are produced by the following radiographic technique? 100 kVp, 150 mA, .5s, with a three phase 6 pulse generator?
10,125
the exposure timer at exposures of more than 10ms should be accurate within
20%
the exposure timer at exposures of 10 ms or less should be accurate within
5 %
the ability of an x-ray imaging system to produce constant radiation output at various combinations of mA and exposure time, resulting in the mAs, is called
reciprocity
output radiation intensity linearity should be within what percent of adjacent mA stations
10%
which of the following tools are use to test focal sport size accuracy?
1.pinhole camera
2. spin top
3. star pattern
1 and 3
what is it called when the focal spot size increases due to age and use
focal spot blooming
test that measures the accuracy of adjacent mA station
exposure linearity
test that measures the accuracy of successive exposures
exposure reproductibility
which waveforms has the lowest percent ripple?
high frequency
a focal spot accuracy test was performed on a tube with a stated focal spot size of 1.0mm. if the measured size after testing was 0.75mm, this is considered to be in acceptable range?
yes or no
yes
how many dots would appear on an image when testing timer accuracy for a single phase fully rectified generator when using .05 sec?
6?
how much time was used if you tested timer accuracy on a single phase half rectified generator if the results produced 3 dots?
0.05 seconds
heat sensors in new generators provide warnings when what percentage of anode heat is reached?
75%
what is MINIMUM amount of lead equivalency in gloves?
0.25mm/Pb
how often does lead have to be tested for damage?
semiannually
What does OSHA stand for?
Occupational Safety and Health Administration
xray tube life may be extended by:
1. using high mAs with low kVp factors
2. avoiding lengthy anode rotation
3. avoiding exposures to a cold anode
2 and 3
what is the allowance parameter for an x-ray tube that has a stated focal spot of 1.5mm
40%
Synchronous spinning top is used on a 3phase unit with a time of 17ms. How large of an arc should appear if the timer is acruate?
6 degrees
Xray system mAs reciprocity has an acceptance parameter of
a. +/- 5%
b. +/- 10%
c. +/- 15%
d. +/- 20%
10%
the x-ray tube must be mounted inside its housing so that the CR exits the housing within ___ degrees of perpendicular
1
which of the follwing will cause lower patient dose?
1. high kVP
2. small field size
3. increased filtation
all the above
what tool is used to measure radiation output?
dosimeter
angulation accuracy must be within
5 degrees
what anode angle will give the best spatial resolution?
2 degrees
The amount of light produced by the output phosphor per unit of x-radiation incident on the input phosphor is termed:
conversion factor
What material is the input phosphor made out of?
cesium iodide
The "dead man" exposure switch ensures that:
the operator cannot be exposed when entering the exam room
Increasing the source to skin distance will increase patient dose. T/F
false
How long does it take to hear an audible signal on the fluoroscopy machine that alerts the radiographer to the amount of time being used?
5 minutes
The table angle indicator and actual angle of the table should not exceed how many degrees?
2 degrees
Which of the following is true when using intensification fluoroscopy?
image is brighter
What is the process called when electrons are emitted from photocathode?
photoemission
What device focuses the photoelectrons within a fluoroscopic image intensification tube?
electrostatic lens
What conversion occurs at the input phosphor of the image intensifier tube?
xrays are converted to light
The light field to radiation field should not exceed what percent of SID in fluoroscopy?
3%
What is the component of a fluoroscopic unit that maintains density and contrast by manipulating mA and kVp?
ABC
automatic brightness control
What material is the photocathode made out of?
cesium & antimony
What conversion occurs in the image intensifier at the photocathode?
light converted to electrons
Fluoroscopy procedures produce the highest occupational exposure to health care workers. During a procedure, where should the dosimeter be worn?
at collar level, above lead apron
Which of the following is true regarding magnification fluoroscopy?
input phosphor size gets smaller
provides the least patient dose?
decrease the image intensifier to patient distance
3 ways to decrease pt dose during fluoro
use largest input phosphor
collimation
shortest II to patient distance
What is the minimum source to tabletop distance for mobile fluoroscopy?
12''
What is the minimum source to tabletop distance for stationary fluoroscopy?
15''
What is the minimum amount of lead equivalent required for the fluoroscopy curtain/drape?
0.25mm pB
Which of the following terms best describes the increase in image brightness resulting from the difference in size between the input and output phosphors?
minification gain
The intensity of the x-ray beam at the tabletop should not exceed ____ R/min for units that are equipped with an automatic brightness stabilization system.
10
Which of the following is the main advantage of using a small input phosphor diameter?
increase spatial resolution
What material is the output phosphor made out of?
zinc cadmium sulfate