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73 Cards in this Set

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  • Back
In many cases, digital fluoroscopy eliminates which of the following?
Postprocedure "overhead" films
A photostimulable phosphor is the active component of what piece of equipment?
Computed radiography imaging plate
In computed radiography, the image plate must be turned into digital form by what device?
Analog-to-digital converter
A mathematical formula used to reconstruct the image in digital imaging is called?
An algorithm
Picture elements in a digital image are called?
Pixels
A digital image is composed of rows and colums known as:
Matrix
Direct digital radiography differs from computed radiography in what way?
The use of fixed detectors that communicate directly with the computer
Window width in computed radiography and digital radiography controls what image property?
Contrast
A graphic display that is constructed to show the radiographer the distribution of pixel values is called:
A histogram
The law stating that the outer shell of an atom can contain no more than eight electrons is called:
Octet rule
Examples of particulate radiation are:
Helium nuclei and beta particles
Elextromagnetic radiation travels:
In waves along a straight path
Electromagnetic radiation travels in bundles of energy called:
Photons
X-rays travels at what speed?
The speed of light, 186,000 miles per second
Waves of radiation are called:
sine waves
Wavelenght is defined as the distance from:
Peak to peak of the wave
Frequency is defined as:
The number of waves passing a point per unit time
The speed of x-rays is based on:
The fact that they are a form of electromagnetic radiation.
Wavelength and frequency are:
Inversely proportional to each other
The x-ray beam will change as it travels through the patient by a process called:
Attenuation
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:
Inverse square law
As radiation strikes matter:
The energy is transferred to the atoms according to the law of conservation of energy
Which statements are true regarding electrostatic charges?
Electrostatics is the study of electric charges at rest; Electrostatic charges concentrate on a conductor in the area of the greatest curvature.
Which statements are false?
The volt is the unit of electric current; The ampere is the unit of eletromotive force; Ohm'law is calculated using the equation VI=R
Electromagnetic induction is the process of causing an electric to flow in a conductor:
When it is placed in the magnetic field of another conductor
The two types of electromagnetic induction are:
Self- induction and mutual induction
Self-induction is used in the operation of what device?
autotranformer
The strength of the magnetic fields in a transformer is increased by:
coiling the wires and letting their magnetic fields overlap
Electricity is supplied to the imaging department by a:
generator
The electricity provided to the radiology department is:
60 Hz Ac
The electricity provided to the radiology department operates at:
120 pulses per second
High-frequency power:
Has almost no ripple
The primary advantage of three-phase power is that:
Voltage never drops to zero
A variable transformer that is used to select kVp for the xray circuit is the:
autotransformer
A transformer that has more turns in the seconday than in the primary coil is called a?
step-up transformer
The transformer used to boost voltage to kilovoltage levels is called a?
Step-up transformer
Voltage coming to the xray machine is kept constant through the use of a:
Line voltage compensator
A step-down transformer:
Steps down voltage
Where does thermionic emission occur?
Cathode
What device is prereading?
kVp meter
What device reduces voltage and provides current to produce an electron cloud or space charge at the filament?
Step-down transformer
What device is electronic, with increments as low as 0.001 second?
timer
What changes AC to Dc?
rectifier
What is surrounded by a negatively chagred focusing cup?
filament
What is composed of solid-state, silicon-based diodes?
Rectifier
What regulates the duration of xray production?
Timer
What is located in the xray circuit between the high-voltage transformer and the xray tube?
rectifier
What measures tube current?
mA meter
What device spins at 3300 to 10,00 rpm?
Anode
What device uses maximum heat storage ability of the tube to deliver mAs?
Falling load generator
What is the source of bremsstrahlung and characteristic rays?
anode
What device increases voltage approximately 500 times?
Step-up transformer
What is the most commonly used AEC?
Ionization chamber
What device always delivers the shorest exposure time possible?
falling load generator
What device is turned by a rotor?
anode
Which of the following is located between the patient and the IR?
Ionization chamber
The filament is kept warm by:
A standby current from the time the xray machine is turned on.
Activating the rotor will?
Reduce tube life
When making an exposure, the radiographer should:
Activate the rotor and the exposure switch in continuous motion.
The process of thermionic emission causes:
Electrons to boil off the filament
The electron stream passes from cathode to anode because of____ passing through the xray tube.
Current
Heat is produced in the xray tube as:
Electrons interect with the target material
Most of the energy conversion in the xray tube produces:
Heat
Xrays are produced as incident electrons interect with target atoms by a process called:
Bremsstrahlung
Xrays are produced as incident electrons interact with inner shell electrons in target atoms by a process called:
Characteristic
What percentage of energy in the xray tube is converted to xrays?
1%
Which are properties of xrays?
Affect film emulsion; Scatter and produce secondary radiation; Invisible to the human eye; Travel in bundles of energy called photons; can ionize matter and gases; Cause phosphors to fluoresce.
The xray beam is:
Heterogeneous or polyenergetic, consisting of many different energies(wavelengths).
The xray emission spectrum consists of:
Discrete spectrum (produced by characteristic rays) and continuous spectrum (produced by brems rays).
The primary purpose of filtration is:
Radiation protection
The amount of material needed to reduce the intensity of the beam by 1/10 is called?
Tenth-value layer
Which statements regarding filtration is true?
Total filtration (not less than 2.5 aluminum equivalent) = inherent filtration(glass envelope,tube housing, oil) + added filtration (aluminum).
Calculating heat units for three-phase, twelve-pulse equipment requires the use of___ as a constant; calculating heat units for single-phase equipment requires the use of ___ as a constant; calculating heat units for three-phase, six-pulse equipment requires the use of ___ as a constant.
1.41, 1, 1.35, because average photon energy is different with each tyoe of equipment.