X- Ray Circuit Flashcards
(106 cards)
1
Q
what are the three main parts of the x ray imaging system
A
operation console
high voltage generator
x ray tube
2
Q
kVp can be referred to by what other terms
A
voltage
energy
quality
penetrability
3
Q
mA is referred to by what other terms
A
current
# of photons
quantity
4
Q
what circuit is the operating console found in
A
primary
5
Q
which components of the imaging system are found in the secondary circuit
A
high voltage generator
x ray tube
6
Q
what is the voltage that the operating console receives
A
220V
7
Q
is the voltage received by the operating console considered to be high or low
A
low
8
Q
the _______ _________ allows the RT to control the tube current and ________
A
operating console
voltage
9
Q
what other items does the operating console have control of
A
line compensator
kVp
mA
exposure time
10
Q
the operating console also contains what
A
autotransformer
11
Q
what is the function of the autotransformer and what is it based on
A
alters intensity
based on self induction
12
Q
describe the function of the line voltage compensator
A
compensates the incoming voltage so that a constant voltage may be used
13
Q
line compensator _____ and ______ the _____ to the tube to keep it ______
A
monitors
adjusts
voltage
constant
14
Q
most systems operate at what voltage
A
220V
15
Q
what is the voltage range
A
110-440V
16
Q
the _______ is first to receive power
A
autotransformer
17
Q
name the two circuits that the autotransformer supplies power to
A
filament circuit
high voltage circuit
18
Q
true or false:
the autotransformer contains two winding wires
A
false
19
Q
the power going to the filament and high voltage circuits from the autotransformer is considered and input or output
A
output from the autotransformer
20
Q
the autotransformer law states that voltage and # of turns are; directly or indirectly proportional
A
directly proportional
21
Q
what is the autotransformer law equation
A
Vs/Vp = Ns/Vs
22
Q
name the three functions of the autotransformer
A
- provides voltage to other circuits
- provides means for kVp
- adjustment of voltage
23
Q
what does kVp determine in reference tot he x-ray beam
A
the quality or penetrability
24
Q
true or false: there is only one kVp selector; explain
A
FALSE; there are two:
Major kVp
Minor kVp
25
the ______ kVp selects factors of 10-20
Major
26
the ______ kVp selects factors of 1-2
Minor
27
what does the kVp meter read
voltage
28
______ controls the quantity of electrons crossing from cathode to anode
mA
29
the number of electrons emitted depends on what
temperature of the filament
30
define thermionic emission
release of electrons from a heated filament
31
what is an ammeter
measures amperage
32
what is the range for filament current
3-5 or 3-6 A
33
what is a space charge
a high number of electrons in a cloud around the cathode (filament)
34
name the effect that causes electrons to only go one at a time from cathode to anode
space charge effect
35
what compensates for the space charge effect
anode will pull over the electrons as it wants/needs them rather than one at a time
36
true or false: when you start the rotor the filament circuit is activated
true
37
is the filament transformer considered a step up or step down transformer
step down
38
the mA selector can also be called what
rheostat
precision resistor
variable resistor
39
what is the function of the mA selector
controls the current
40
what is the function of the focal spot selector
select the size of the focal spot
41
name and describe the two sizes of focal spots
small - detail (low heat tolerance)
| large - high heat tolerance
42
what is a falling load generator
it begins at a max mA and drops during exposure
43
what is the result in exposure time with a falling load generator
minimum exposure time
44
with long term use of a falling load generator what could be the result to tube
shortened lifespan of the tube
45
what is the main function of the exposure timers
control the duration of the filament heating
46
name the five types of exposure timers
1. mechanical timers
2. synchronous timers
3. electronic timers
4. mAs timers
5. AEC
47
what does the mA meter do
monitors x ray current
48
describe the location of the mA meter
secondary side of the high voltage step-up transformer
49
true or false: the mA meter is located at a point where it receives voltage and measures current
and correct the statement if needed
false; the mA meter is located at a point where it receives NO voltage and ONLY measures current
50
what is the function of the guard timer
terminates the exposure after a set amount of time; to prevent continuous irritation of a patient for an extended time
51
if an exposure timer fails to turn off; after how long after will the guard timer shut the exposure off
after 6 seconds
52
the filament steps down voltage approximately how much
12V
53
what is the primary side of the filament transformer composed of and what is the current and voltage through it
thin copper wire with current .5-1A and 150V
54
what is the secondary side of the filament transformer composed of and what is the current and voltage through it
thick copper wire 12v w/current of 5-8A
55
true or false: the secondary side of the filament transformer is heavily insulated to protect the wire
true
56
why is the secondary side of the filament transformer insulated and why
to protect it b/c it is connected to the high voltage supply of the tube
57
true or false: the timer circuit is included in the main circuits
false; it is separate
58
where is the timer circuit located
primary side of the step up high voltage transformer; within the primary circuit (operating console)
59
what is the main function of the filament transformer
to lower the voltage to protect the filament
60
the synchronous timer, electronic timer, and mAs timers are what kind of timers?
manual
61
what is the only automatic timer
AEC
62
describe the synchronous timer
driven by a motor at 60 revolutions per second
63
true or false: the synchronous timer can be used for serial exposures and does not have to be reset
false: the synchronous timer CANNOT be used for serial exposures and DOES have to be reset
64
which of the timers is the most accurate
electronic timer
65
electronic timers provide a narrow or wide range of selection of time intervals
wide
66
by what increment does the electronic timer allow for selections
as small as 1ms
67
true or false; the synchronous timer can be used for serial exposures
true
68
which of the timers is the only one located in the secondary circuit
mAs timer
69
what does the mAs timer do
monitors the product of mA and exposure time and terminates when it reaches the desires mAs
70
what is a mAs timer used in conjunction with
falling load generator and w/a discharge capacitor
71
the AEC measures what
quantity of radiation reaching the IR
72
name the two different IR's that have been used with the AEC; modern and older
older: photomultiplier
| modern ionization chamber
73
how does the ionization chamber work
when ionization level is reaches the exposure terminates
74
true or false the AEC always has a back up timer
true
75
what kind of back up timer does the AEC have
solid state radiation detector
76
how accurate is the solid state radiation detector
within 1 ms
77
what does the high voltage generator do
converts low voltage supplied from the power company into high kilovoltage and the high amperage to mA
78
what are the three primary parts of the high voltage generator
1. high voltage transformer
2. filament transformer
3. rectifiers
79
name the two types of rectifiers
1. vacuum tube rectifier
| 2. solid state rectifier
80
what is vacuum tube rectifier composed of
cathode (negative)
| anode (positive)
81
what material is a solid state rectifier made of
silicon semiconductor
82
what can a solid state rectifier also be called
solid-state diode
83
which of the two types of rectifiers are most commonly used in modern imaging
solid state rectifiers
84
what are the two types of semiconductors within a solid state rectifier
N-type
| P-type
85
describe N-Type
loosely bound electrons that are freely movable
86
describe P-Type
holes that tend to attract electrons
87
true or false: solid state rectifiers can be termed as crystals
True
88
if a positive potential is placed on the p-side of the p-n junction will there be current flow?
yes
89
if a positive potential is places on the n-side of the p-n junction will there be current flow?
no
90
true or false; a solid-state diode conducts current flow in multiple directions
false; current only flows in one direction
91
true or false; unrectified voltage is not converted from AC to DC
true
92
in terms of unrectified voltage when does current flow? positive or negative half of the cycle
current flows during the negative half
93
the Hz on the primary side and secondary side are _____
equal
94
what happens in half-wave rectification
the negative voltage is removed
95
when does current flow in half wave rectification
during the positive part of the cycle
96
true or false; the full wave form appears on the output
false; only half of the waveform appears on the output
97
half-wave rectification results in what
a series of positive pulses separated by gaps
98
what is the disadvantage of half-wave rectification
wastes half of the incoming power supply
| requires twice the exposure time
99
how many pulses per second does half wave rectification produce
60 pulses/second
100
how many diodes are used in half wave rectification
0-2
101
what happens in full wave rectification
negative waveform is converted to a positive waveform
102
true or false; there are gaps in full wave rectification
false; there are no gaps b/c the negative waveform was converted to a positive
103
how many rectifiers are used in full wave rectification
4
104
what is the advantage of full wave rectification
there are no gaps
| and exposure times are cut in half
105
how many pulses does full wave rectification have per second
120 pulses/second
106
true or false; current passes through the circuit in bother the neg and pos wave during full wave rectification
true
