Lesson 3 (p. 63-end)

Question 1

Ceiling Support System

Answer 1

most common
allows for longitudinal and transverse travel
has preferred detent position

Question 2

Floor to Ceiling Support

Answer 2

column positioned on a single floor support system with mounting rails

Question 3

C-arm support

Answer 3

used in the operating room

very flexible and has options for mounting

Question 4

leakage radiation

Answer 4

photons that escape from the housing except from the port

Question 5

Leakage radiation must not exceed ____ mR/hr at ___ meter as per federal standards

Answer 5

100 , 1

Question 6

dielectric oil

Answer 6

electric insulator and heat absorber from x-ray production

Question 7

Glass Envelope / Metal Enclosure

Answer 7

Encloses the entire cathode and anode assembly

Question 8

What does the Glass Envelope not enclose?

Answer 8

stator of induction motor

Question 9

What is the glass enveloped typically made of ?

Answer 9

pyrex

Question 10

The glass envelope is sealed tight to prevent?

Answer 10

the collision of high speed electrons and gas molecules

Question 11

Some glass envelope are unique. For example, _______-target tubes for ______ uses a special metallic _______ window to avoid attenuating the low-energy photons.

Answer 11

molybdenum , mammography , beryllium

Question 12

Off focus radiation is also known as?

Answer 12

extra focal radiation or ghosting

Question 13

Off Focus Radiation

Answer 13

photons are shot away from the focal spot (off focus)

Question 14

Off focus radiation is not the same as what?

Answer 14

scatter radiation

Question 15

Off-focus radiation may contribute to as much as ____ % of the total primary beam.

Answer 15

25-30%

Question 16

filament (cathode)

Answer 16

emits electrons to give a tube current

Question 17

focusing cup

Answer 17

metal shroud surrounding the filament

Question 18

space charge

Answer 18

electron cloud near the filament

Question 19

target

Answer 19

region of the anode struck by electrons emitted by the filament

Question 20

Filament

Usually made of thoriated ______ material

Promotes higher _____ _______

Has a high melting point of ________ and not likely to burn out or ________.

Answer 20

tungsten

thermionic emission

3410 C , vaporize

Question 21

What are the 2 materials other than tungsten used to make a filament and what are their melting points?

Answer 21

rhenium 3170 C

molybdenum 2200 C

Question 22

Describe the size of the filament in a x-ray tube.

Answer 22

coil is .1-.2 mm in diameter, 1-2 mm wide and 7-15 mm long

Question 23

Focusing Cup

Answer 23

metal shape cup that houses the filament.

Question 24

What is the focusing cup made of ?

Answer 24

molybdenum or nickel

Question 25

cathode

Answer 25

gives off electrons used in the production of x-rays by thermionic emission

Question 26

Focusing Cup

The electron beam from a negatively-charged electron from the cathode tends to spread out due to _________ _______. Causes some electrons to ____ the target or anode.

The _________ focusing cup condenses the electron beam to a small area on the anode. ______ the spread of the electron stream striking the anode.

Answer 26

electrostatic repulsion , miss

negatively-charged , reduces

Question 27

The effectiveness of the focusing cup depends on what?

Answer 27

size and shape
strength of its charge
filaments size and shape
position of the filament within the focusing cup

Question 28

Stator

Answer 28

stationary coil windings in the protective house but outside the x-ray tube glass envelope

Question 29

Copper

Answer 29

common reddish metallic element that’s ductile and malleable

Question 30

What is one of the best conductors of heat and electricity ?

Answer 30

copper

Question 31

Tungsten

Answer 31

metal element that is the principle component of the cathode and anode

Question 32

Target

Answer 32

area of the anode struck by the electrons from the cathode

Question 33

The target is also known as ?

Answer 33

the focus , the focal point , the focal spot , the focal track

Question 34

Actual Focal Spot (AFS)

Answer 34

region of the anode target where electrons interact to produce x-rays

Question 35

Effective Focal Spot (EFS)

Answer 35

the focal spot projected onto the patient and the image receptor

Question 36

Anode Heel Effect

Answer 36

geometry of an angled anode target radiation intensity is the cathode side

Question 37

The _______ the target or anode angle the _______ the heel effect.

Answer 37

smaller , larger

Question 38

The _______ the target or anode angle the ______ effective focal spot. The electron beam _____ the _____.

Answer 38

smaller, less , stays the same

Question 39

Heat Units (HU) for single-phase units

Answer 39

HU = kVp x mA x seconds

Question 40

Heat Units three-phase 6-pulse units

Answer 40

HU = 1.35 x kVp x mA x seconds

Question 41

Heat Units for three-phase 12-pulse units

Answer 41

HU = 1.40 x kVp x mA x seconds

Question 42

when using heat units formula remember to?

Answer 42

also multiply by number of films if that’s included

Question 43

What are the parts for X-ray tube external structures ?

Answer 43

Support structure
Protective housing
Enclosure