Refresher Part II

Question 1

When x-yr is centered above the examination table at the standard SID, the x-ray is in a […]

Answer 1

Preferred detent position

Question 2

Support system equipped in interventional radiology suites
Ceiling mounted and provide for very flexible x-yr tube positioning

Answer 2

C-Arm support system

Question 3

External components of X-ray tube

Answer 3

Protective housing
Glass or metal enclosure

Question 4

[protective housing] Special section where where x-rays are emitted

Answer 4

Window

Question 5

X-rays that are emitted through the window

Answer 5

Useful beam

Question 6

X-rays that escape through the protective housing

Answer 6

Leakage radiation

Question 7

Level of reduction of leakage radiation in the protective housing

Answer 7

Less than 1 mGa/hr at 1 m

Question 8

Guards against excessive radiation exposure and electric shock
Provides mechanical support and protects damage caused by rough handling

Answer 8

Protective housing

Question 9

Function of oil in X-ray tube

Answer 9

Serves as both an insulator against electric shock and as a thermal cushion

Question 10

Made of Pyrex and able to withstand the tremendous heat generated
Maintains a vacuum inside the tube which allows for more efficient production and longer tube life

Answer 10

Glass enclosure

Question 11

Two electrodes in X-ray tube

Answer 11

Cathode ad anode

Question 12

Maintain constant electric potential between the electrons of the tube current and the enclosure

Answer 12

Metal enclosure

Question 13

Internal components of an X-ray tube [cathode]

Answer 13

Filament
Focusing cup

Question 14

The negative side of the X-ray tube

Answer 14

Cathode

Question 15

It is a coil of wire approx. 2mm in diameter and 1 or 2 cm long
Emits electrons when it is heated

Answer 15

Filament

Question 16

The phenomenon when the current through the filament is sufficiently high, the outer-shell electrons of the filament atoms are “boiled off” and ejected from the filament

Answer 16

Thermionic emission

Question 17

Makes up the filament
Provides for higher thermionic emission
Does not vaporize easily
Melting point is 3410 degrees

Answer 17

Thoriated tungsten

Question 18

1% to 2% added to tungsten filament to enhance efficiency of thermionic emission and prolongs tube life

Answer 18

Thorium

Question 19

Metal shroud where the filament is embedded
Negatively charged

Answer 19

Focusing cup

Question 20

Effectiveness of focusing cup is determined by […], […] and […]

Answer 20

Size, shape and position of the filament

Question 21

Designed to be turned on and off rapidly
Used in portable capacitor discharge imaging systems

Answer 21

Grid-controlled tubes

Question 22

Cloud of electrons

Answer 22

Space charge

Question 23

Phenomenon where space charge makes it difficult for subsequent electrons to be emitted bu the filament because of electrostatic repulsion

Answer 23

Space charge effect

Question 24

Positive side of X-ray tube
Conducts electricity and radiates heat and contains target

Answer 24

Anode

Question 25

Types of anode

Answer 25

Stationary and rotating anode

Question 26

Anode tube used in dental and portal imaging systems

Answer 26

Stationary anode

Question 27

Internal components [anode]

Answer 27

Target Rotating anode

Question 28

Three functions of anode

Answer 28

Electrical conductor [receives electrons from emitted by cathode] Mechanical support Thermal dissipater

Question 29

Most common anode materials

Answer 29

Copper, molybdenum and graphite

Question 30

Material of choice for target

Answer 30

Tungsten

Question 31

Three main reasons [tungsten material for target]

Answer 31

1. Atomic number -74 [high efficiency x-ray production] 2. Thermal conductivity 3. High melting point - 3400 degrees C

Question 32

Target material for special X-ray tubes [mammography]

Answer 32

Molybdenum and rhodium - low k characteristic, low atomi number

Question 33

[atomic number] Tungsten Molybdenum Rhodium

Answer 33

74 42 45

Question 34

Allows the electron beam to interact with much larger target area; therefore, heating of anode is not confined to one small spot

Answer 34

Rotation anode

Question 35

Used to turn the anode

Answer 35

Electromagnetic induction motor

Question 36

Induction motor two principal parts - separated by glass enclosure

Answer 36

Stator and rotor

Question 37

[induction motor] part outside the glass Consists of a series of electromagnets equally spaced around the neck of the tube

Answer 37

Stator

Question 38

[induction motor] part inside enclosure Shaft made of bars of copper and soft iron fabricated into one mass

Answer 38

Rotor