ch. 2 anatomy of machine Flashcards Preview

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Flashcards in ch. 2 anatomy of machine Deck (45)
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1
Q

what controls the # of electrons produced by the filament

A

cathode

2
Q

process of changing alternating current to a direct current

A

recitification

3
Q

what reduces the x-ray machine input voltage from 110-220V to 10 V to prevent burnout of the cathode filament

A

step-down transformer

4
Q

what controls the length of exposure

A

timer switch

5
Q

AKA self-rectifiers

A

valve tubes

6
Q

what allows the flow of electrons in one direction only

A

valve tubes

7
Q

what is the peak energy of the x-rays that determines the quality called

A

kilovoltage (kVp)

8
Q

what part of the x-ray tube consists of a coiled wire tungsten filament that emits electrons when heated

A

actual focal spot

9
Q

what is the small area of the target were electrons collide on the anode

A

focal spot

10
Q

the ____ is made up of molybdenum because it has a high melting point and is a poor heat conductor

A

focusing cup

11
Q

___ acts as a conductor of heat and draws the heat away from the tungsten target

A

oil

12
Q

what type of anode is found in dental and small portable radio graphic units

A

stationary

13
Q

what type of anode continually provides a cooler surface for the electron stream to hit

A

rotating

14
Q

restricting device used to control the size of the primary x-ray beam

A

collimator

15
Q

what are the 4 factors that an x-ray tube rating is based upon

A

focal spot size, target angle, anode speed, electrical current

16
Q

what unit is the x-ray tubing rating expressed in

A

kilowatts

17
Q

stationary anode focal spot size

A

small

18
Q

using a high kVp and a low mAs helps prevent

A

damage to anode

19
Q

what noise happens when anode bearing fails

A

grinding metal/ no noise

20
Q

how far away should the radiographer be from the machine

A

6 feet

21
Q

what increases the incoming voltage of 110-220 V to 1000 V

A

step up transformer

22
Q

a decrease of intensity on the anode side of x-ray beam due to angle

A

heel effect

23
Q

creates a partial shadow of the object being imaged

A

halo effect

24
Q

what size focal spot is ideal and why

A

small; greater detail

25
Q

what is the #1 cause of x-ray tube failure

A

cathode failure

26
Q

how can cathode failure be avoided

A

let the machine heat up

27
Q

what is gassy tube

A

glass envelope damage; occurs when air gets into glass tube

28
Q

the line-voltage compensator is associated with the ___ and is automatic in most new machines

A

autotransformer

29
Q

what is the maximum electrical and thermal rating for portable x-ray units

A

60-90 kVp

30
Q

what is the maximum electrical and thermal rating for table top x-ray units

A

40-120 kVp

31
Q

coning aka

A

collimation

32
Q

due to heel effect, what part of the animal should be placed toward the cathode

A

large size

33
Q

what occurs during 1st phase of the exposure button

A

filament heats and anode spins

34
Q

what occurs during 2nd phase of the exposure button

A

radiograph is created

35
Q

__ kVp and __mAs techniques should be used as often as possible to prevent anode damage

A

high;low

36
Q

what is the glass vacuum tube that contains the cathode and the anode of the x-ray tube

A

glass envelope

37
Q

metal deposits on the inner wall of the envelope that attract electrons from the cathode

A

arcing

38
Q

control panel of the machine

A

console

39
Q

low energy circuit, when heated, releases electrons from their orbits

A

filiment

40
Q

amount of electical energy being applied

A

milliamperage

41
Q

creates constant electrical potential across the tube

A

full wave rectification

42
Q

converts alternating to direct current

A

half wave rectification

43
Q

what is used to focus the beam

A

lead shutters

44
Q

recessed area where the filament lies, directing the electrons toward the anode

A

focusing cup

45
Q

effect of making the focal spot appear smaller when viewed from the position of the film

A

line focus principle