x-ray tube construction

Question 1

Lead lined structure to absorb non useful x-rays generated at the focal spot

Answer 1

protective housing

Question 2

_________________ connect to the tube within the housing which acts as an electrical insulator to reduce the risk of shock

Answer 2

Two large electrical cables

Question 3

Radiation that is produced in directions other than the target window and escapes the protective housing is referred to as ________________

Answer 3

leakage radiation

Question 4

Protective housing MUST reduce leakage radiation to less than __________

Answer 4

100 mR/hr

Question 5

housing helps cool x-ray tube in 2 ways

Answer 5

1. forced air cooling
2. oil

Question 6

anode is ______, cathode is _________

Answer 6

positive, negative

Question 7

two main components of the x-ray induction motor

Answer 7

stator (fixed), rotor (rotating)

Question 8

a rotating anode makes a focal spot a _________

Answer 8

focal tract

Question 9

the maximum stress load that a material can take before breaking

Answer 9

tensile strength

Question 10

Steeper angles of the target create __________________________ which then increases the sharpness of the image and allows smaller structures to be visualized in the radiograph

Answer 10

smaller effective focal spot sizes

Question 11

Steeper angles of the target create smaller effective focal spot sizes which then ___________________ and _______________________

Answer 11

increases the sharpness of the image, allows smaller structures to be visualized in the radiograph

Question 12

what is the actual focal spot?

Answer 12

the area of the target that is being struck by the filament electrons

Question 13

what is the effective focal spot?

Answer 13

the x-ray beam area as seen from the patient’s perspective

Question 14

As long as the target angle is less than ____°, the effective focal spot will always be smaller than the actual focal spot

Answer 14

45 degrees

Question 15

Generally, the target angle is between ____° with the average being around __°

Answer 15

7-18, 12

Question 16

A small filament will create a (larger/smaller) actual focal spot which will then create a (larger/smaller) effective focal spot

Answer 16

smaller, smaller

Question 17

The smaller the effective focal spot, the _____________________. Therefore, it is necessary to _______________________

Answer 17

sharper the image will be; keep this as small as practically possible

Question 18

two drawbacks to line focus principle

Answer 18

1. if angle of target is too small, it may not be big enough for 14x17 field at 40 SID
2. the angle causes the intensity of the x-ray beam to be less on the anode side (anode heel)

Question 19

If the center of the beam was 100% of the intensity, then the anode side would average as low as ___% of that intensity and the cathode side would have ___%

Answer 19

75%, 120%

Question 20

Rotating anodes are made of tungsten as well and for the same reasons although other materials such as _________

Answer 20

Rhenium

Question 21

Rhenium may be added to increase __________ as well as ____________

Answer 21

thermal capabilities as well as tensile strength

Question 22

The rotating disc is made of ______________ and is covered with the ________________________ and is connected to a molybdenum core within a copper shaft

Answer 22

Molybdenum, target material (tungsten or tungsten/molybdenum)

Question 23

The rotating disc is made of Molybdenum and is covered with the target material (tungsten or tungsten/molybdenum) and is connected to a _________________________

Answer 23

molybdenum core within a copper shaft

Question 24

Molybdenum is used as a base for the disc and core because of its _________________ and __________________

Answer 24

light weight which makes it easier to rotate and its incredible ability to dissipate heat

Question 25

Filaments are usually between _________ in length and ________ wide

Answer 25

7-15 mm, 1-2 mm

Question 26

Filaments are made of tungsten with _____________________ added to increase thermionic emission and tube life

Answer 26

1-2% thorium

Question 27

why is thorium added to the tungsten filament?

Answer 27

increase thermionic emission and tube life

Question 28

what is the focusing cup made of?

Answer 28

nickel

Question 29

effectiveness of the focusing cup depends on several things

Answer 29

1. The size and shape of the cup
2. .The charged placed on the cup
3. The size and shape of the filaments within the cup
4. The position of the filaments within the cup

Question 30

the size of the effective focal spot ___________ as the target angle decreases

Answer 30

decreases

Question 31

One half of the range between the wave peak and valley over which the sine waves varies describes

Answer 31

amplitude