chapter 7 ( The X ray tube)

Question 1

Which of the following will not damage the X-Ray tube?

Answer 1

Exceeding the ideal field size for an exposure

Question 2

The main method of heat transfer from the focal spot/target to the rest of the anode is

Answer 2

conduction

Question 3

An exposure rate of 100 mR/hr is the maximum allowed

Answer 3

leakage rate

Question 4

The effective focal spot size is
the actual filament size.

Answer 4

smaller than

Question 5

____________enclosures allow for more support and a constant potential between the tube current and enclosure.

Answer 5

Metal

Question 6

A loud grinding sound from a tube is most likely due to

Answer 6

damaged ball bearings

Question 7

Thermionic emission is the emission of

Answer 7

electrons from a heated cathode

Question 8

In a fixed anode, there are_____
allowable heat loads and a_______
overall target area.

Answer 8

low, small

Question 9

The space charge effect______.

Answer 9

occurs in the vicinity of the cathode

Question 10

Localized pitting on the anode can occur from_______.

Answer 10

a single excessive exposure

Question 11

The external structure of the X-Ray tube includes

Answer 11

support structure, protective housing, and tube enclosure

Question 12

The filament is made of_____.

Answer 12

tungsten

Question 13

Oil is added to the tube housing, creating a layer between the housing and tube enclosure to do what of the following?

Answer 13

remove heat from the X-Ray tube enclosure

Question 14

When saturation is achieved at a fixed filament current, tube current

Answer 14

remains the same with increasing kVp

Question 15

Which of the following could allow for an increase in heat capacity of an anode?

Answer 15

a. An increased anode diameter
b. A faster rotation speed
c. A larger focal spot X

d. All of the above

Question 16

Because of the line focus principle, the effective focal spot size decreases with decreasing

Answer 16

target angle

Question 17

Which of the following is not done by the protective housing?

Answer 17

Protection from scatter

Question 18

The impact of the heel effect on the image is reduced by positioning the cathode

Answer 18

over the thickest part of the patient

Question 19

What is the most common cause of abrupt tube failure?

Answer 19

open filament

Question 20

The heel effect is more pronounced

Answer 20

with a small target angle

Question 21

What does the focusing cup do?

Answer 21

help emitted electrons to a small region on the target

Question 22

The main method of heat transfer from the anode to the tube enclosure is

Answer 22

Radiation

Question 23

Extrafocal or off-focus radiation is produced from

Answer 23

rebounding electrons

Question 24

The negative side of the X-Ray tube holds the

Answer 24

filament

Question 25

Thermotropic emission allows______ to leave the filament.

Answer 25

electrons

Question 26

The target of the rotating anode is usually made of

Answer 26

tungsten

Question 27

Thorium is added to the filament to increase

Answer 27

thermionic efficiency

Question 28

The______ is the source of X-Rays in the tube

Answer 28

focal spot

Question 29

The filaments lay inside the focusing cup which has _____ with respect to the filaments in order to ______ electrons to the beam.

Answer 29

negative potential, repel

Question 30

The term "isotropic" means

Answer 30

X-Rays are emitted in all directions

Question 31

The typical target angle in general radiography is_____ degrees.

Answer 31

15

Question 32

The effective focal spot is determined by the target angle and the_____.

Answer 32

filament size

Question 33

The only way to increase saturation tube current is to increase

Answer 33

filament current

Question 34

The part that actually turns the anode is the

Answer 34

rotor

Question 35

The______ current is always less than the______ current.

Answer 35

tube, filament

Question 36

The rotating anode is turned by the induction motor, which uses a

Answer 36

changing magnetic field

Question 37

The X-Ray intensity is lower on the anode side of the tube because of the

Answer 37

heel effect

Question 38

The X-Ray tube current____.

Answer 38

is controlled by the filament current

Question 39

Each tube has its own radiographic rating chart to show

Answer 39

maximum exposure techniques

Question 40

The best way to avoid cracking a cold anode is to

Answer 40

warm it with several low-technique exposures

Question 41

Dual focus tubes usually have two

Answer 41

filaments

Question 42

What are the main functions of the anode?

Answer 42

a. Support the actual target region b. Acts as electrical conductor c.Remove the heat generated D. (All of the above )

Question 43

The main method of heat transfer from the tube housing to the room is

Answer 43

convection

Question 44

If excessive heat is conducted through the rotor, it could

Answer 44

damage ball bearings in the rotor

Question 45

Generally, for the same total mAs, the small focal spot results in exposure times that are ____ a large focal spot

Answer 45

greater than

Question 46

The is/are outside the tube enclosure.

Answer 46

stators

Question 47

As an X-Ray tube ages, the inside can become coated with tungsten, which can cause in the tube.

Answer 47

arcing

Question 48

For the same kVp and mAs setting, what waveform would technically generate the most heat units?

Answer 48

high frequency

Question 49

A molybdenum shaft is used to connect the anode to the rotor because it

Answer 49

is a poor heat conductor

Question 50

X-Ray tube failure may be due to

Answer 50

a. a broken filament Flag question b. overheating of the anode c. damage to the ball bearings d. lack of anode rotation (All of the above)

Question 51

The filament of an X-Ray tube is about_____ in length.

Answer 51

1-2 cm

Question 52

The most important property to consider when choosing an anode material is

Answer 52

high melting point

Question 53

What is the most probable result of a single exposure made on a tube if the factors slightly exceed those permitted by the radiographic rating chart?

Answer 53

The useful life of the tube would be reduced

Question 54

The most widely used support structure for the X-Ray tube is the

Answer 54

ceiling support system

Question 55

The effective focal spot size is largest

Answer 55

on the cathode side of the tube