X-ray Tube Registry Review

Holding down the rotor switch without making an exposure can result in: 1. shortened filament life 2. shearing of the anode 3. excessive mA flowing through the tube 4. wear and tear on the rotor bearings

1 & 4

Which of the following factors will effect size of the focal spot? 1. angle of the anode 2. speed of the rotation 3. size of the filament

1 and 3

The technologist presses the rotor switch to being an exposure. What happens in the x-ray circuit when the rotor switch is depressed? 1. the anode starts turning 2. x-rays are produced 3. kVp surges through the x-ray tube 4. the filament is heated to thermionic emission

1 and 4

If the angle on a x-ray tube anode is decreased from 12 degrees to 7 degrees it will result in a decrease in: 1. size of the focal spot 2. loading capacity of the tube 3. field coverage at short distances

1, 2, & 3

Damage to the x-ray tube can be reduced by: 1. not rotating the tube housing rapidly when the rotor is turning 2. making sure exposures are safe by checking a radiographic rating chart 3. turning off the main power supply each night 4. gradually warming up the tube after an extended period of inacticity

1, 2, & 4

Tungsten is the principle material used in the formation of the: 1. surface of the target of a rotating anode 2. surface of the target of a stationary anode 3. wire used as the x-ray tube filament

1, 2, and 3

A modern dual focus x-ray tube contains: 1. one filament 2. two filaments 3. one anode

2 and 3

The anode of a modern rotating anode tube is generally composed of tungsten and: 1. copper 2. rhenium 3. molybdenum

2 and 3

The two methods of x-ray production that take place in the x-ray tube are: 1. pair production 2. bremsstrahlung 3. electron projection 4. characteristic 5. coherent

2 and 4

The main function of the Pyrex glass that forms the protective envelope of the x-ray tube is: 1. The containment of the electron stream near the filament 2. The containment of the vacuum within the x-ray tube 3. The production of the static electrical field around the filament

2 only

The general formula that is used to determine the anode heat units created with a fully rectified x-ray tube is:

HU = mA x kV x time

The discovery of x-rays was made by Wilhelm Roentgen in 1895 while experimenting with a partially evacuated glass tube called a/an: a. Crooke's tube b. Coolidge tube c. Edison tube d. Compton tube

a. Crooke's tube

The speed and energy of the electron stream as it passes across an x-ray tube is primarily controlled by the: a. applied kilovoltage b. vacuum material c. temperature of the filament d. focus cup voltage

a. applied kilovoltage

The angle on the anode of a x-ray tube helps to insure that more of x-ray photons produced at the target are: a. directed toward the patient b. transmitted through the glass housing c. scattered in all directions equally

a. directed toward the patient

As the anode target angle increases: a. effective focal spot size increases b. target rotating speed increases c. radiation intensity on the central ray increases

a. effective focal spot size increases

The large filament is used during radiography when the heat load is: a. high, and visibility of detail is less important b. high, and visibility of detail is important c. low, and visibility of detail is important

a. high, and visibility of detail is less important

The amount of space charge (aka the number of electrons) created at the cathode is primarily controlled by the: a. impressed amperage b. impressed kV c. tube current

a. impressed amperage

Tungsten is the choice material for x-ray anodes for each of the reasons listed below except: a. low atomic number b. thermal conductivity c. high atomic number d. high melting point

a. low atomic number

Thermionic emission occurs in proportion to the amount of ___ set by the technologist. a. mA b. distance c. kVp d. time

a. mA

In most x-ray tubes, there are two filaments to: a. provide 2 focal spots b. ensure saturation current c. reduce space charge effects d. produce higher-energy xrays

a. provide 2 focal spots

The primary purpose of the glass or metal enclosure of an x-ray tube is to: a. provide a vacuum b. control leakage radiation c. control off-focus radiation

a. provide a vacuum

The heel effect: a. requires that the cathode be positioned to the thicker anatomy b. occurs only with rotating anode x-ray tubes c. is reduced with a focusing cup

a. requires that the cathode be positioned to the thicker anatomy

When a radiographer changes from a small to a large focal spot for an exposure, he/she is actually: a. selecting a larger filament b. increasing the filament-anode distance c. increasing the diameter of the anode disk d. increasing the angle of the anode disk

a. selecting a larger filament

In a modern diagnostic x-ray tube, the majority of the heat that is produced during the x-ray production process is created and concentrated on the: a. surface of the focal tract/anode b. inner surface of the tube envelope c. surface of the filament

a. surface of the focal tract/anode

The principal disadvantage of the use of a smaller focal spot during a radiographic exposure is: a. the limitation of the amount of mA that can be selected b. the limitation of the kilovoltage peak to diagnostic levels c. an increase in the amount of focal spot blur

a. the limitation of the amount of mA that can be selected

In a modern diagnostic x-ray tube, the vast majority of the energy of the electron stream striking the target of the anode is converted into: a. thermal energy (heat) at the surface of the anode b. x-radiation just below the surface of the anode c. compression waves just above the surface of the anode d. high frequency sound waves at the surface of the focus cup

a. thermal energy (heat) at the surface of the anode

Which is the proper sequence of materials traversed by the x-ray beam after leaving the anode of the x-ray tube? a. tube envelope, oil, aluminum filter b. oil, tube envelope, aluminum filter c. aluminum filter, tube envelope, oil d. oil, aluminum filter, tube envelope

a. tube envelope, oil, aluminum filter

In a rotating anode, the focal track is coated with _____: a. tungsten and rhenium b. tungsten and graphite c. lead and molybdenum

a. tungsten and rhenium

The thin, flattened surface of the x-ray tube envelope which allows for the minimum absorption of x-rays is termed the: a. xray window b. primary diaphragm c. primary shutter d. focus cup

a. xray window

The major reason that tungsten is the material chosen for the components of a modern x-ray tube is its high melting point of about: a. 1300 degrees C b. 3400 degrees C c. 2300 degrees C d. 1000 degrees C

b. 3400 degrees C

The target of a modern rotating anode is beveled or inclined to an angle in the range of _________: a. 3-7 degrees b. 7-17 degrees c. 15-25 degrees d. 25-37 degrees

b. 7-17 degrees

Most of the x-rays in a diagnostic beam of 75 kVp are ____________ x-rays: a. hard b. Brems c. soft d. characteristic

b. Brems

In order to prevent movement of electrons from the anode to the cathode during the exposure cycle, the type of current employed for an x-ray tube is: a. alternating current b. direct current c. inversion current d. multiphase current

b. direct current

X-ray tube current: a. flows through both filaments at the same time b. is controlled by the filament current c. usually varies from 50 to 1000 mA d. is the current that flows through the filament

b. is controlled by the filament current

The focusing cup of the cathode has a(n) ___ charge. a. neutral b. negative c. positive

b. negative

What is extrafocal radiation? a. photons that were directed back toward the cathode b. photons that were not produced at the focal spot c. photons that did not leave the protective housing d. photons that were absorbed in the dielectric oil

b. photons that were not produced at the focal spot

The structure that limits the amount of leakage radiation coming from the x-ray tube is the: a. glass/metal envelope b. protective housing c. copper stemmed rotor d high voltage cables

b. protective housing

If the x-ray tube envelope is glass, it is composed of a heat resistant material called: a. bakelite b. pyrex glass c. lead glass

b. pyrex glass

The main reason for using the line-focus principle is to: a. reduce exposure time b. reduce the effective focal spot size c. increase x-ray intensity d. reduce the actual focal spot size

b. reduce the effective focal spot size

The reduction of effective focal spot size from about 2 mm to 1 mm can be accomplished by: a. decreasing the voltage impressed on the focus cup b. selecting the smaller of the two filaments c. increasing mA and kVp values d. increasing speed at which the anode rotates

b. selecting the smaller of the two filaments

The electrons emitted from the filament may be referred to as ____________ : a. positive charge b. space charge c. negative cloud d. current cloud

b. space charge

Which of the following is a component of an electromagnetic induction motor? a. target disc b. stator c. cathode d. filament

b. stator

The temperature of the filament in a modern x-ray tube is most closely related to: a. the time selected for a radiographic exposure b. the amount of current impressed on the filament c. the speed of the electron stream across the tube d. time required to accelerate the anode to its maximum speed

b. the amount of current impressed on the filament

The process by which heating of the filament results in the liberation of electrons in the x-ray tube is called: a. isotropic propagation b. thermionic emission c. thermoluminescence

b. thermionic emission

Which of the following is not a function of the anode? a. conduction of electricity b. thermionic emission c. xray production d. thermal conduction

b. thermionic emission

To produce an x-ray beam consisting of some Brems and some K-characteristic x-rays while using a tungsten target, the kVp must be at a minimum of: a. 50 b. 60 c. 70 d. 90

c. 70

The line-focus principle concerns the effect of the target angle and effective focal spot size. Which is a true statement of this principle? a. The actual focal spot is projected onto the patient. b. As target angle decreases, the effective focal spot increases c. The actual focal spot is larger than the effective focal spot d. Radiation intensity is greatest on the cathode side of the tube

c. The actual focal spot is larger than the effective focal spot

The x-ray tube housing functions to ___________: a. reduce extra-focal radiation b. reduce penumbra c. absorb leakage radiation d. absorb primary radiation

c. absorb leakage radiation

In a modern x-ray tube, the positively-charged electrode that serves as the target for the electron stream, is the: a. primary filament b. induction coil c. anode disk d. electron gun

c. anode disk

The focusing cup: a. is on the positive side of the x-ray tube b. is usually made of thoriated tungsten c. confines the electron beam to a small area of the anode d. is slightly positive with respect to the filament

c. confines the electron beam to a small area of the anode

In a stationary anode tube, the target is imbedded in an anode made of: a. tungsten b. molybdenum c. copper d. rhenium

c. copper

X-rays used for radiographic imaging are produced at the _________ in the x-ray tube. a. filament b. focusing cup c. focal spot d. none of the above

c. focal spot

Which of the following is an advantage of a rotating anode tube over a stationary anode tube? a. higher kVp capacity b. reduced heel effect c. higher heat capacity

c. higher heat capacity

The type of motor that turns the anode in an x-ray system is called: a. localized b. aligned c. induction d. synchronous

c. induction

This type of x-ray tube envelope has become increasingly more common: a. styrofoam b. plexiglass c. metal d. calcium hydrate

c. metal

Radiation produced at other places in the tube besides the focal spot is called: a. mid focus b. scatter c. off-focus d. leakage

c. off-focus

Contrast in the radiographic image is produced when x-ray photons interact with matter and _________ has taken place. a. compton effect b. coherent scatter c. photoelectric effect d. pair production

c. photoelectric effect

The amount of heat storage capacity of a rotating anode is dependent upon all of the following EXCEPT: a. diameter of the anode disk b. speed of the anode rotation c. prep (boost) time d. size of the focal spot

c. prep (boost) time

The hollow cylinder attached to the anode: a. capsule b. switch c. rotor d. stator

c. rotor

The external structure of the x-ray tube consists of three parts: a. x-ray tube, protective housing and high-voltage generator b. anode, cathode, and high-voltage generator c. support structure, protective housing, and the glass or metal enclosure d. x-ray tube, high-voltage generator and image receptor

c. support structure, protective housing, and the glass or metal enclosure

The durability and efficiency of the tungsten filament is often improved by the addition of the metal __________: a. silver b. lead c. thorium d. copper

c. thorium

A vacuum is maintained in the x-ray tube because: a. the anode won't turn without a vacuum b. the filament gets hotter more quickly c. x-ray production is more efficient d. insulating oil needs a vacuum

c. x-ray production is more efficient

The melting point for tungsten is: a. 2483 degrees C b. 5698 degrees C c. 4856 degrees C d. 3370 degrees C

d. 3370 degrees C

All of the following are advantages of a rotating type anode tube EXCEPT: a. an increased rate of heat dissipation from the surface of the anode b. an increase in the allowable exposures (tube ratings) for the unit c. a reduction in the amount of roughening that will occur on the focal tract d. a reduction in the amount of low energy photons produced during an exposure

d. a reduction in the amount of low energy photons produced during an exposure

Most x-ray tubes used for radiography: a. do not emit leakage radiation b. operate in the space charge-limited mode c. have a fixed anode d. are dual focus tubes

d. are dual focus tubes

The main reason tungsten is employed as filament material in an x-ray tube is its: a. low phosphorescence b. high degree of flexibility c. high atomic number d. high melting point

d. high melting point

The material that is often added to a rotating anode disk to reduce surface defects and cracks, is called: a. silver b. cesium c. lead d. rhenium

d. rhenium

The heel effect occurs because of: a. reduced tube current b. the shape of the filament c. the shape charge effect d. x-ray absorption in the anode

d. x-ray absorption in the anode