review questions for X-ray Equipment Operation
the collimator must be accurate to a level of?
+/- 2% of SID
choose all the following that are accurate
-a magnetic field always surrounds an electrical charge in motion -current flows back and forth in AC -current flows in one direction in DC -a conductor allows the flow of electrons -the volt is the unit of potential difference -the path of electrical current is called the circuit
choose all that are properties of x-rays
-affect film emulsion -scatter and produce secondary radiation -invisible to the human eye -can ionize matter and gases -travel in bundles called photons -cause phosphors to fluoresce
choose all of the following statements that are accurate regarding electrostatic charges
-electrostatics is the study of electric charges at rest -electrostatic charges concentrate on a conductor in the area of greatest curvature
what percentage of energy in the x-ray tube is converted to x-rays?
1%
calculating the heat units for 3 phase, 12 pulse equipment requires the use of ___ as a constant; calculating heat units for single-phase equipment requires the use of ___ as. a constant; calculating the heat units for 3 phase, 6 pulse equipment requires the use of a ___ as a constant.
1.41; 1.0; 1.35
exposure linearity must be accurate to within?
10%
kVp must be accurate to within?
10% of the control panel setting
fluoroscopy exposure rate may not exceed?
100 mGya per minute
the electricity to the radiology department operates at?
120 pulses per second
the number of mAs used fir analog fluoroscopy is?
3-5
the increase in average photon energy when using 3 phase, 6 pulse equipment compare with single-phase equipment is?
35%
the increase in average photon energy when using 3 phase, 12 pulse equipment compared with using single-phase equipment is?
41%
exposure reproducibility must be accurate to within?
5%
the accuracy of the timer must be within?
5% of the time chosen for exposures OVER 10 ms
when a quality control test is preformed to ensure that the penetrating ability of the x-ray beam is accurate, the result must be within what amount of the control panel setting?
50%
the electricity provided to the radiology department is?
60 Hz AC
the feature that automatically adjusts kVp and mA during fluoroscopy is called?
ABC
the speed of x-rays is based on?
The fact that they are a form of electromagnetic radiation
the filament is kept warm by?
a standby current from the time the x-ray machine is turned on
when making an exposure, the radiographer should?
activate the rotor and exposure switch in one continuous motion
in digital fluoroscopy, the image must be turned into digital form by what device?
analog-to-digital converter
what device is turned by a rotor?
anode
what device spins at 10,000-12,000 rpm?
anode
what is the source of bremsstrahlung and characteristic rays?
anode
at what speed to x-rays travel?
at the speed of light; 186,000 miles per second
what is the smallest particle of an element that retains the characteristics of the element?
atom
the x-ray beam changes as it travels through the patient by a process called?
attenuation
what device may be used to ensure consistency of radiographic quality from one exposure to the next?
automatic exposure control
a variable transformer that is used to select kVp for the x-ray circuit is the?
autotransformer
self induction is used in the operation of what device?
autotransformer
x-rays are produced as incident electrons are slowed going past the nuclei of target atoms by a process called?
bremsstrahlung
where does thermionic emission occur?
cathode
x-rays are produced as incident electrons collide with inner shell electrons in target atoms by a process called?
characteristic
the strength of the magnetic fields in a transformer is increased by?
coiling the wires and letting their magnetic fields overlap
what type of current is required for proper operation of the x-ray tube?
direct
3 phase, 6 pulse full-wave rectification produces?
direct current with 13% ripple
3 phase, 12 pulse full-wave rectification produces?
direct current with 4% ripple
the x-ray emission spectrum consists of?
discrete spectrum and continuous spectrum (produced by characteristics) (produced by brems)
heat is produced in the x-ray tube as?
electrons interact with the target material
the process of thermionic emission causes?
electrons to boil off the filament
the test that measures the accuracy of adjacent mA stations is?
exposure linearity
the test that measures the accuracy if successive exposures is?
exposure reproducibility
what device always delivers the shortest exposure time possible?
falling load generator
what devices uses maximum heat storage ability of the tube to deliver mA?
falling load generator
what type of x-ray machine uses a continually decreasing mA for the shortest times possible?
falling load generator
which of the following is surrounded by a negatively charged focusing cup?
filament
the latest digital fluoroscopic units use?
flat panel detectors similar to DR
total brightness gain achieved using an image intensifier equals?
flux gain times magnification gain
the primary type of grid used in diagnostic imaging is?
focused
electricity is supplied to the imaging department by a?
generator
high frequency power?
has almost no ripple
most of the energy conversion in the x-ray tube produces?
heat
examples of particulate radiation are?
helium nuclei and beta particles
the x-ray beam is?
heterogeneous or polyenergetic; consisting of many different energies (wavelengths)
electromagnetic radiation travels?
in waves along a straight path
the intensity of radiation is inversely proportional to the square of the distance between the source of radiation and the person receiving it. This describes the?
inverse square law
wavelength and frequency are?
inversely proportional to each other
what is the most commonly used AEC?
ionization chamber
which of the following is located between the patient and the image receptor?
ionization chamber
which of the following devices is prereading?
kVp meter
the force with which the electron stream passes from cathode to anode is a result of _____ passing through the x-ray tube?
kilovoltage
voltage coming to the x-ray machine is kept constant through the use of a(n)?
line voltage compensator
which of the following measures tube current?
mA meter
the law stating that the outer shell of an atom can contain no more than eight electrons is called?
octet rule
the portion of the image intensifier tube that converts electron energy to visible light is the?
output phosphor
wavelength is defined as the distance from?
peak to peak of the wave
AEC's may be tested using?
phantoms
the portion of the image intensifier tube that converts visible light to electrons is the?
photocathode
x-rays travel as bundles of energy called?
photons
marks on the focal track of the anode resulting from bombardment of electrons are called?
pitting
in many cases, digital fluoroscopy eliminates which if the following?
postprocedure "overhead" images
single-phase, full wave rectification produces?
pulsating direct current with 120 pulses per second and 100% ripple
programs that deal with the safe and reliable operation of equipment and programs that address all aspects of the delivery and radiology services are called, respectively?
quality control and quality assurance
the primary purpose of filtration is?
radiation protection
what changes AC to DC?
rectifier
what is located in the x-ray circuit between the high-voltage transformer and the x-ray tube?
rectifier
which of the following is composed of solid-state silicon-based diodes?
rectifier
activating the rotor?
reduces tube life
resolution of the television system may be measured using the following tool(s)
resolution test pattern
the two types of electromagnetic induction are?
self induction and mutual induction
waves of radiation are called?
sine waves
which device reduces voltage and provides current to produce an electron cloud or space charge at the filament?
step-down transformer
a transformer that has more turns in the secondary coil than in the primary coil is call a?
step-up transformer
what device increases voltage approximately 500 times?
step-up transformer
what is the transformer used to boost voltage to kilo-voltage levels called?
step-up transformer
a step-down transformer?
steps down voltage
the amount of material needed to reduce the intensity of the beam by 1/10 is called?
tenth-value layer
as radiation strikes matter?
the energy is transferred to the atoms according to the law of conservation of energy
when a predetermined level of ionization is reached in the ionization chamber, what does the machine do?
the exposure is terminated
effective quality control and quality assurance programs are required for accreditation by?
the joint commission
the image intensifiers conversion factor is expressed as the ratio of?
the luminance of the output phosphor to the exposure rate at the input phosphor
what is atomic mass?
the number of protons plus the number of neutrons
frequency is defined as?
the number of waves passing a point per unit time
what regulates the duration of x-ray production?
timer
which device is electronic with a setting as low as 0.001?
timer
which of the following statements regarding filtration is true?
total filtration (not less than 2.5 mm aluminum equiv.) = inherent filtration + added filtration
the primary advantage of the three-phase power is that?
voltage never drops to 0
electromagnetic induction is the process of causing an electrical current to flow in a conductor
when it is placed in the magnetic field of another conductor
the input phosphor of the image-intensifier tube converts?
x-ray energy to visible light
