Deck 6: The X-Ray Tube

Question 1

The focusing cup has a/an ____ charge.

A)neutral
B)atomic
C)positive
D)negative

Answer 1

negative

Question 2

Pitting of the anode commonly occurs

A)when the unit is not warmed up properly.
B)when the anode is off-focus.
C)with extended use.
D)when the kilovoltage is too high.

Answer 2

with extended use.

Question 3

All of the following are related except one.Select the one that is NOT RELATED.

A)a source of electrons
B)a vacuum
C)thermionic emission
D)a large potential difference

Answer 3

thermionic emission

Question 4

A filament may break due to

A)evaporation.
B)deposition.
C)increased sensitivity.
D)vaporization.

Question 5

Filament materials are chosen primarily for their

A)atomic number.
B)high melting points.
C)ability to vaporize easily.
D)high boiling points.

Question 6

Melting of the anode commonly occurs

A)when the unit is not warmed up properly.
B)with extended use.
C)when the kilovoltage is too high.
D)when the stator fails and the rotor ceases to turn.

Question 7

In order to time the x-ray exposure with rapid inspiration on an infant,

A)three phase generators are preferred.
B)the exposure button and prep are pressed simultaneously.
C)exposure may be initiated as fast a 0.10 sec.
D)less expensive single-phase generators are desirable.

Question 8

X-ray photon production occurs at the

A)anode.
B)cathode.
C)filament.
D)stator.

Question 9

As more and more electrons build up in the area of the filament, their negative charges oppose the emission of additional electrons.This phenomenon is known as

A)thermionic emission.
B)biased cloud formation.
C)space charge effect.
D)current saturation.

Question 10

The function of the cathode is to produce

A)a focal point.
B)an electrical connection to the rectifier.
C)a thermionic cloud.
D)a grounding effect.

Question 11

The area of the focal spot that is projected out of the tube toward the object being radiographed is the

A)effective focal spot.
B)line focus.
C)actual focal spot.
D)x-ray tube long axis.

Question 12

All of the following are preferred cathode filament materials EXCEPT

A)copper.
B)tungsten.
C)rhenium.
D)molybdenum.

Question 13

The physical area of a rotating anode focal track, affected by the cathode electron beam, is the

A)effective focal spot.
B)effective focal track.
C)actual focal spot.
D)projected focal track.

Question 14

Which of the following would affect the production of a thermionic cloud?

A)filament diameter
B)filament length
C)filament temperature
D)all of the above

Question 15

Cracking of the anode typically occurs

A)with extended use.
B)when the anode is off-focus.
C)when a cold anode is hit with a high kVp exposure.
D)when the cathode cup touches the anode, causing a short.

Question 16

The exact point on the anode where the x-ray beam emanates is the

A)focusing cup.
B)focal spot.
C)stator.
D)rotor.

Question 17

Driving the thermionic cloud from the cathode to the anode requires

A)a grid biased anode.
B)a small voltage.
C)a large amperage.
D)a small amperage.

Question 18

The actual focal spot is controlled by the

A)thickness of the anode disc.
B)length of the filament.
C)anode rotation speed.
D)angle of the cathode focusing cup.

Question 19

All of the following are part of the cathode assembly EXCEPT

A)filament.
B)stator.
C)focusing cup.
D)associated wiring.

Question 20

Tungsten is the metal of choice for the source of x-ray photons because of its

A)high atomic number.
B)low melting point.
C)low mass number.
D)low cost.

Question 21

The most common diagnostic radiography target angle is ____ degrees.

A)12
B)24
C)45
D)54

Question 22

The protective housing controls leakage and scatter radiation through

A)evaporation.
B)vaporization.
C)absorption.
D)condensation.

Question 23

List the three functions of the x-ray tube anode.

Question 24

What is the function of the filament?

Question 25

When radiographing a wedge-shaped anatomical structure such as the femur, the thicker portion of the anatomy should be positioned

A)under the cathode end of the tube.
B)in the exact center of the beam. as it is most intense in the center.
C)off center laterally to negate the heel effect.
D)under the anode side of the tube.

Question 26

To determine the allowable combination of exposures factors, thus preventing x-ray tube damage,

A)a tube rating chart is referenced after exposure to check correctness.
B)the automatic exposure circuit is activated.
C)an x-ray tube rating chart is checked prior to exposure.
D)an anode cooling chart is referenced prior to exposure.

Question 27

List the three parts of the anode assembly.

Question 28

As the angle of the anode increases and the incident electron beam size remains the same, the effective focal spot size

A)increases.
B)decreases.
C)remains the same.
D)cannot be determined.

Question 29

To cover a 14 in.x 17 ft field at 40 ft, a ____-degree target angle is required.

A)3
B)5
C)7
D)12

Question 30

As the actual focal spot size increases, the effective focal spot size

A)increases.
B)decreases.
C)remains the same.
D)cannot be determined.

Question 31

The function of the stator and rotor assembly is to

A)create a vacuum.
B)rotate the anode.
C)insulate the anode.
D)disrupt the electromagnets of the induction motor.

Question 32

Leakage radiation from the lead-lined housing must not exceed

A)10 mR/hr measured at 40 inches.
B)100 mR/min measured at 36 inches.
C)10 mR/min measured at the tube head.
D)100 mR/hr measured at 1 meter.

Question 33

The problem of off-focus radiation

A)is particularly important with digital detectors.
B)distorts the digital histogram.
C)may result in suboptimum digital images.
D)all of the above

Question 34

Insulation of the high-voltage components of the tube and absorption of the heat produced by x-ray production is achieved through the use of

A)a small fan.
B)a vacuum.
C)a stator.
D)dielectric oil.

Question 35

The rotor is located ____ the stator and ____ the envelope.

A)inside; inside
B)inside; outside
C)outside; outside
D)outside; inside

Question 36

The use of the line-focus principle causes a problem known as the ____ effect.

A)space charge
B)quantum mottle
C)anode heel
D)saturation current

Question 37

In which direction should the anode be placed for an AP projection of the femur?

Question 38

The only portion of the anode assembly placed outside the vacuum of the envelope is the

A)stator.
B)rotor.
C)rotating disc.
D)molybdenum neck.

Question 39

List two other names for the anode target.

Question 40

What type of radiation is composed of photons not produced at the actual focal spot?

A)off-focus
B)extrafocal
C)both a and b
D)primary

Question 41

How many heat units are generated by an exposure of 70 kVp, 300 mA, and 0.1 second on a 1 $\phi$ rectified unit?

Question 42

Using the following exposures factors on a high-frequency generator, how many joules of electrical energy are being created
400 mA
95 kVp
26 ms

Question 43

How many heat units are generated by three (3) exposures of 100 kVp, 400 mA, and 0.01 second using a high frequency generator?

Question 44

How many heat units are generated by an exposure of 70 kVp, 400 mA, and 0.1 second on a 3 $\phi$ rectified unit?

Question 45

List the three primary functions of the x-ray tube's protective housing.

Question 46

A conscientious technologist will always handle the x-ray tube assembly with care, particularly when the x-ray tube has been used for high mAs and kVp exposures over a short period of time.Technologists are cautioned about moving the x-ray tube assembly quickly and with "jerking" movements.Explain why this is important to remember.

Question 47

The use of stress-relief anodes is effective at dealing with what inherent characteristic(s) of x-ray production?

Question 48

Why is a vacuum created in the x-ray tube?

Question 49

How many heat units are generated by an exposure of 100 kVp, 400 mA, and 0.01 second on a high-frequency unit?

Question 50

Metal envelope x-ray tubes are gaining in popularity.Explain some key advantages to a metal housing x-ray tube.