LRA 211 Radiology: Questions & Answers
*Which of the following is a physical property of x-rays?*
a. Travel in straight lines
b. Refract and reflect similar to visible light
c. Are visible in the dark
d. May be deflected by magnets - ANSWER:a. Travel in straight lines
Travel of x-ray photons is in a straight line, until there is interaction with matter. The direction of the
primary beam is then altered. Photons possess no electrical charge and are not affected by either
magnetic or electric fields, and they cannot be refracted or reflected as per visible light.
As the wavelength of x-ray photons shortens, the energy of the x-ray beam will...
a. Stay the same
b. Lengthen
c. Decrease
d. Increase - ANSWER:d. Increase
As with other forms of electromagnetic radiation, as the wavelength becomes shorter, the frequency of
the x-ray beam increases. Frequency is measured by the number of cycles that pass a stationary point
per second. The higher the frequency, the greater the energy and penetrating power.
The kVp setting on an x-ray machine controls the...
a. Quality of the x-ray beam
b. Quantity of x-ray beams
c. Number of electrons emitted
d. Focal spot size - ANSWER:a. Quality of the x-ray beam
,Kilovoltage peak, or kVp, determines the peak energy of the x-rays, which determines the penetrating
power, a quality of the x-ray beam.
The milliampere-seconds (mAs) setting on an x-ray machine controls the...
a. Quality of the beam
b. Quantity of x-rays emitted
c. Speed of electrons emitted
d. Wavelength of the beam - ANSWER:b. Quantity of x-rays emitted
Milliampere seconds, or mAs, determines the amount of the electrical energy applied to the filament per
second and determines the number of x-rays produced during the exposure.
During an exposure, electrons in the x-ray tube travel from the...
a. Anode to the cathode
b. Anode to the target
c. Cathode to the anode
d. Cathode to the filament - ANSWER:c. Cathode to the anode
The cathode provides the source of the electrons at the filament, and the kilovoltage directs the
electrons to the anode during the exposure.
To produce x-rays, a great deal of energy in an x-ray tube is converted into heat. The ratio of heat
generated to x-ray production is generally considered to be...
a. 1%: 99%
b. 99%: 1%
c. 50%: 50%
d. 75%: 25% - ANSWER:b. 99%: 1%
99x more heat than actual x-rays is produced in an x-ray tube. Part of this is the heat of the cathode
filament, and part is produced when the electron beam strikes the focal spot on the anode target.
Modern x-ray tubes are designed to prevent this large amount of heat from destroying the x-ray tube.
,The acceleration of the electrons and their ultimate striking energy is determined by the...
a. Milliamperage (mA)
b. Kiloyoltage (kVp)
c. Milliamperage-seconds (mAs)
d. Exposure time (Time) - ANSWER:b. Kiloyoltage (kVp)
The kilovoltage peak (kVp) determines the maximum speed of the electrons flowing across the x-ray
tube. This determines the maximum energy of the x-ray photons produced and thus their penetrating
power.
When depressing the "prep" switch on a rotating anode x-ray machine, you are effectively...
a. Determining the acceleration of the electrons
b. Taking the exposure
c. Heating up the focal spot and spinning the rotating anode
d. Heating up the filament and spinning the rotating anode - ANSWER:d. Heating up the filament and
spinning the rotating anode
Before the electrons can be boiled off, the filament has to be at a proper temperature, and the anode
must be rotating at the correct speed in preparation for the electrons and subsequent heat. The focal
spot is that area on the target that receives the electrons. The kVp determines the acceleration and the
exposure is not made until the exposure button is depressed.
Regarding the production of x-rays in the x-ray tube, the...
a. Purpose of the anode is to provide a source of electrons
b. Target and focal spot are provided by the cathode
c. Cathode side of the tube is positively charged, and the anode is negatively charged
d. Cathode includes the filament and the focusing cup - ANSWER:d. Cathode includes the filament and
the focusing cup
The x-ray tube provides the source of the electrons, a method of accelerating them, a target for the
interaction of the electrons to change into x-ray photons and heat, a method of heat dissipation, and a
, glass envelope to maintain the evacuated path for the accelerated electrons to travel. The negatively
charged cathode provides the source of electrons through the heated filament, the focusing cup helps
direct the path, and the kVp provides the method of acceleration. The anode provides the target and
focal spot.
What transformer in an x-ray machine controls the temperature of the filament?
a. Step-up transformer
b. Step-down transformer
c. Autotransformer
d. Self-rectifying transformer - ANSWER:b. Step-down transformer
Minimum energy is needed for heating the tungsten filament, so a step-down transformer is placed
between the cathode filament and the power supply to the x-ray machine. The extreme incoming
voltage of 110 to 220 volts would cause instant evaporation of the filament. The step -down transformer
decreases the incoming voltage to 10 V. A step-up transformer, choice a, is necessary for increasing the
incoming voltage to kilovoltage to transport the electrons at a fast enough speed to produce x-rays.
The heel effect is going to be more noticeable with...
a. Larger film, longer focal-film distance, and higher kVp
b. Larger film, shorter focal-film distance, and lower kVp
c. Smaller film, shorter focal-film distance, and higher kVp
d. Smaller film, longer focal-film distance, and lower kVp - ANSWER:b. Larger film, shorter focal-film
distance, and lower kVp
Because of the angle of the anode, there is a greater intensity of the x-ray beam toward the cathode
side. As with beams of light, there is increasing spread of the beam from the source. The divergent
effects are more noticeable with larger film, because a greater percentage of the beam is affected. The
full effect of the beam, and the variation in intensity, are more noticeable with shorter focal-film
distance. At lower kVp there is a greater variation in the intensity of the beam as compared to higher
kVp, which leads to a more noticeable heel effect.
Full-wave rectification means that...
a. The bottom half of alternating current is not used.
*Which of the following is a physical property of x-rays?*
a. Travel in straight lines
b. Refract and reflect similar to visible light
c. Are visible in the dark
d. May be deflected by magnets - ANSWER:a. Travel in straight lines
Travel of x-ray photons is in a straight line, until there is interaction with matter. The direction of the
primary beam is then altered. Photons possess no electrical charge and are not affected by either
magnetic or electric fields, and they cannot be refracted or reflected as per visible light.
As the wavelength of x-ray photons shortens, the energy of the x-ray beam will...
a. Stay the same
b. Lengthen
c. Decrease
d. Increase - ANSWER:d. Increase
As with other forms of electromagnetic radiation, as the wavelength becomes shorter, the frequency of
the x-ray beam increases. Frequency is measured by the number of cycles that pass a stationary point
per second. The higher the frequency, the greater the energy and penetrating power.
The kVp setting on an x-ray machine controls the...
a. Quality of the x-ray beam
b. Quantity of x-ray beams
c. Number of electrons emitted
d. Focal spot size - ANSWER:a. Quality of the x-ray beam
,Kilovoltage peak, or kVp, determines the peak energy of the x-rays, which determines the penetrating
power, a quality of the x-ray beam.
The milliampere-seconds (mAs) setting on an x-ray machine controls the...
a. Quality of the beam
b. Quantity of x-rays emitted
c. Speed of electrons emitted
d. Wavelength of the beam - ANSWER:b. Quantity of x-rays emitted
Milliampere seconds, or mAs, determines the amount of the electrical energy applied to the filament per
second and determines the number of x-rays produced during the exposure.
During an exposure, electrons in the x-ray tube travel from the...
a. Anode to the cathode
b. Anode to the target
c. Cathode to the anode
d. Cathode to the filament - ANSWER:c. Cathode to the anode
The cathode provides the source of the electrons at the filament, and the kilovoltage directs the
electrons to the anode during the exposure.
To produce x-rays, a great deal of energy in an x-ray tube is converted into heat. The ratio of heat
generated to x-ray production is generally considered to be...
a. 1%: 99%
b. 99%: 1%
c. 50%: 50%
d. 75%: 25% - ANSWER:b. 99%: 1%
99x more heat than actual x-rays is produced in an x-ray tube. Part of this is the heat of the cathode
filament, and part is produced when the electron beam strikes the focal spot on the anode target.
Modern x-ray tubes are designed to prevent this large amount of heat from destroying the x-ray tube.
,The acceleration of the electrons and their ultimate striking energy is determined by the...
a. Milliamperage (mA)
b. Kiloyoltage (kVp)
c. Milliamperage-seconds (mAs)
d. Exposure time (Time) - ANSWER:b. Kiloyoltage (kVp)
The kilovoltage peak (kVp) determines the maximum speed of the electrons flowing across the x-ray
tube. This determines the maximum energy of the x-ray photons produced and thus their penetrating
power.
When depressing the "prep" switch on a rotating anode x-ray machine, you are effectively...
a. Determining the acceleration of the electrons
b. Taking the exposure
c. Heating up the focal spot and spinning the rotating anode
d. Heating up the filament and spinning the rotating anode - ANSWER:d. Heating up the filament and
spinning the rotating anode
Before the electrons can be boiled off, the filament has to be at a proper temperature, and the anode
must be rotating at the correct speed in preparation for the electrons and subsequent heat. The focal
spot is that area on the target that receives the electrons. The kVp determines the acceleration and the
exposure is not made until the exposure button is depressed.
Regarding the production of x-rays in the x-ray tube, the...
a. Purpose of the anode is to provide a source of electrons
b. Target and focal spot are provided by the cathode
c. Cathode side of the tube is positively charged, and the anode is negatively charged
d. Cathode includes the filament and the focusing cup - ANSWER:d. Cathode includes the filament and
the focusing cup
The x-ray tube provides the source of the electrons, a method of accelerating them, a target for the
interaction of the electrons to change into x-ray photons and heat, a method of heat dissipation, and a
, glass envelope to maintain the evacuated path for the accelerated electrons to travel. The negatively
charged cathode provides the source of electrons through the heated filament, the focusing cup helps
direct the path, and the kVp provides the method of acceleration. The anode provides the target and
focal spot.
What transformer in an x-ray machine controls the temperature of the filament?
a. Step-up transformer
b. Step-down transformer
c. Autotransformer
d. Self-rectifying transformer - ANSWER:b. Step-down transformer
Minimum energy is needed for heating the tungsten filament, so a step-down transformer is placed
between the cathode filament and the power supply to the x-ray machine. The extreme incoming
voltage of 110 to 220 volts would cause instant evaporation of the filament. The step -down transformer
decreases the incoming voltage to 10 V. A step-up transformer, choice a, is necessary for increasing the
incoming voltage to kilovoltage to transport the electrons at a fast enough speed to produce x-rays.
The heel effect is going to be more noticeable with...
a. Larger film, longer focal-film distance, and higher kVp
b. Larger film, shorter focal-film distance, and lower kVp
c. Smaller film, shorter focal-film distance, and higher kVp
d. Smaller film, longer focal-film distance, and lower kVp - ANSWER:b. Larger film, shorter focal-film
distance, and lower kVp
Because of the angle of the anode, there is a greater intensity of the x-ray beam toward the cathode
side. As with beams of light, there is increasing spread of the beam from the source. The divergent
effects are more noticeable with larger film, because a greater percentage of the beam is affected. The
full effect of the beam, and the variation in intensity, are more noticeable with shorter focal-film
distance. At lower kVp there is a greater variation in the intensity of the beam as compared to higher
kVp, which leads to a more noticeable heel effect.
Full-wave rectification means that...
a. The bottom half of alternating current is not used.
