Physics 13-1 Final Flashcards
(150 cards)
0
Q
What is located btw step-up transformer and XR tube?
A
rectifier
1
Q
What is located btw the auto-transformer and step-up transformer?
A
kVp meter
2
Q
what is located at secondary side of step-up transformer?
A
mA meter
3
Q
two basic types of induction?
A
self and mutual
4
Q
a transformer converts:
A
electrical potential to higher or lower intensity
5
Q
What works under the principle of self-induction?
A
auto-transformer
6
Q
what determines quality of XR?
A
kVp
7
Q
what determines quantity of XR?
A
mA and exposure time
8
Q
heating of a coil of wire to produce electrons
A
thermionic emission
9
Q
flow of electrons from filament to anode
A
tube current
10
Q
what converts A/C to D/C?
A
rectifier
11
Q
the current to a transformer must be supplied by a(n)
A
A/C source
12
Q
variations in power distribution to XR are corrected by the
A
line voltage compensator
13
Q
the first component to receive power in the XR circuit is
A
the auto-transformer
14
Q
what circuit provides electrons for the XR tube current?
A
filament
15
Q
thermionic emission at the filament determines the __________ across the XR tube during an exposure
A
milliamperage
16
Q
step-down transformer is located in the ________ circuit
A
filament
17
Q
most accurate type of timer
A
electronic
18
Q
the AEC terminates the exposure when
A
sufficient rad reaches the IR
19
Q
location of ionization chamber
A
btw pt and IR
20
Q
f(x) of photodiode
A
convert light to electric signal
21
Q
the principle material used in the formulation of a solid state diode
A
silicon
22
Q
process by which A/C is converted to pulsating D/C
A
rectification
23
Q
type of unit most likely to possess the smallest voltage ripple
A
high frequency unit
24
a 3 phase 12 pulse wave form has ___ ripple
4%
25
a high frequency wave form has ___ ripple
1%
26
a 3 phase 6 pulse unit has an effective kV of about ____ of the peak kVp
86%
27
during capacitor discharge, the voltage falls at a rate of
1 kV/mAs
28
the electron cloud around the filament
space charge
29
tungsten is the material of choice for the target b/c of what 3 reasons?
high atomic #, high thermal conductivity, high melting point
30
"the effective focal spot size is always SMALLER than the actual focal spot size"
line focus principle
31
smaller the anode angle, the _______ the heel effect
larger
32
anode angle and effective focal spot size are
directly proportional
33
anode angle and heel effect are
indirectly proportional
34
taking advtg of heel effect, thicker anatomical parts positioned under the
cathode
35
the effective focal spot size is larger on what side?
cathode
36
most frequent cause of tube failure
electron arcing from the filament
37
what controls the duration of the XR exposure?
timing circuit/exposure switch
38
what can be adjusted to control the quantity of the XR
mA selector
39
what is capable of manipulating the input voltage into the XR circuit
line compensator
40
what controls the voltage in the filament circuit
step-down transformer
41
what can be adjusted to increase the penetration power of the XR
kVp selector
42
the smallest quantity of electromagnetic energy
photon
43
in sine wave, D from crest to crest (valley to valley)
wavelength
44
of wavelengths that pass a point of observation per second
frequency
45
in sine wave, the shorter the wavelength, the _____ its frequency
higher
46
energy of a photon is directly proportional to its
frequency
47
only diff btw XRs and gamma rays
origin
48
describes the relationship btw rad intensity and the D from the rad source
inverse square law
49
when white light goes through a prism
refraction
50
study of fixed/stationary electric charge
electrostatics
51
fundamental unit of electric charge
coulomb
52
"electrostatic force is directly proportional to the product of the electrostatic charges and inversely proportional to the square of the D btw them"
Coulomb's law
53
"when an object becomes electrified, the electric charges are uniformly distributed throughout the object or on its surface"
electrostatic law #3
54
"electric charge of a conductor is concentrated along the sharpest curvature of its surface"
Electrostatic Law #4
55
unit of electric potential
volt
56
silicone and germanium
semiconductors
57
the property of some materials to exhibit no resistance below certain critical temps
superconductivity
58
any property of the circuit that opposes/hinders the flow of the current
resistance
59
4 factors that affect resistance (of conductor)
material, diameter, length, temp
60
"voltage across the total circuit (or any portion thereof) is equal to the current multiplied by the resistance"
Ohm's law
61
electrons flowing alternatively in opposite direction
A/C
62
____ is equal to one ampere of current flowing through an electric potential of 1 volt
1 watt
63
any charged particle in motion creates...
magnetic field
64
the direction of the magnetic field is _______ to the motion of a charged particle
perpendicular
65
ability of a material to attract the lines of magnetic field intensity
magnetic permeability
66
degree to which various materials can be magnetized
magnetic susceptibility
67
what is considered paramagnetic?
MRI contrast
68
what works under the principle of self-induction?
auto-transformer
69
what represents transformer law?
Vs/Vp=Ns/Np
70
transformer loss due to the resistance of the wire
copper loss
71
an electric current can be induced in a coil of wire if its placed near a(n)
electromagnet
72
reduction of rad intensity due scattering/absorption
attenuation
73
gamma rays are produced in the ______ of an atom
nucleus
74
photons w the highest frequencies have the
shortest wavelengths
75
electrostatic force is _______ proportional to the D btw charges and _______ proportional to the product of the charges
inversely, directly
76
the charges on an electrified object are distributed
evenly throughout the object
77
_____ is a source of D/C
battery
78
an A/C is represented by a _______ line
sinusoidal
79
What is Ohm's law?
V=IR
80
SI unit of magnetic field strength
tesla
81
what type of material can be made magnetic when placed in an external magnetic field?
ferromagnetic
82
quantity of matter as described by its energy equivalence
mass
83
has form, occupies space
matter
84
ability to do work
energy
85
rate of doing work
power
86
measures occupational dose
rem
87
measures rad in air
roentgen
88
SI unit of mass
kg
89
atoms and molecules are the fundamental building blocks of ______
matter
90
radio waves, light, XRs
electromagnetic energy
91
ionizing rad is capable of removing _______ from atoms as it passes through matter
electrons
92
largest source of manmade ionizing rad in public
diagnostic XRs
93
Wilhelm Roentgen discovered XRs while experimenting w the
Crookes tube
94
radioactive material measured in
curies
95
Ex of ionizing rad
gamma rays
96
velocity of light
3 x 10^8 m/s
97
Newton's 2nd law
F=MA
98
a measure of 10^-3 rads is a
millirad
99
who invented fluoroscopy?
Thomas Edison
100
"atom" 1st used by
the greeks
101
smallest particle that has all the properties of an element
atom
102
who developed the periodic table?
mendeleev
103
pos charged nucleus surrounded by neg charged electrons in well-defined orbits
Bohr atomic model
104
fundamental particles of an atom
neutron, proton, electron
105
the chem element is determined by the # of?
protons in the atom
106
binding energies/energy levels of electrons are represented by their
shells
107
atom w same # of protons, but diff # of neutrons
isotope
108
when atoms of various elements combine, they form
molecules
109
atom that gains/loses 1+ electrons
ion
110
max # of electrons that can exist in an electron shell is calculated by
2n^2
111
innermost electron shell
K
112
shell # aka
principal quantum #
113
the least penetrating form of ionizing rad
alpha particles
114
the _____ of electromagnetic rad is constant
velocity
115
T required for a quantity of radioactivity to be reduced to 1/2 its original value
half life
116
alpha particles are compared to a _______ nucleus
Helium
117
the force that keeps an electron in orbit is the
centripetal and centrifugal forces
118
How do you convert Fahrenheit to Celsius?
Tc = 5/9 (Tf - 32)
119
How to calculate HU for 3 phase, 6 pulse?
HU=kVp x mA x s x 1.35
120
How to calculate HU for 3 phase, 12 pulse?
HU=kVp x mA x s x 1.41
121
equation for kinetic energy
KE=1/2mv^2
122
How do you increase the KE of electrons traveling from filament to anode?
raise kVp
123
what happens to KE of projectile electron when it interacts w tungsten target?
converts to 99% thermal energy and 1% electromagnetic XR
124
Characteristic rad?
XR released as result of photoelectric effect (when projectile electron interacts w K-shell of target)
125
relationship of effective energy of the char rad and the atomic number of the target material
direct
126
type of rad when projectile electron interacts w nuclear field of target atom
Bremsstrahlung
127
in diagnostic range, most XRs are
Brems
128
min kVp required to produce char rad
69 kVp
129
at 100 kVp, what percentage is char and brems?
15% char, 85% Brems
130
char rad has what type of energy
fixed/discrete
131
15% rule?
15% increase in kVp is equal to doubling mAs (to keep a constant optical density)
132
What 4 factors affect XR quantity?
current/mAs, volt/kVp, filtration, D
133
What 2 factors affect XR quality?
volt/kVp, filtration
134
mAs/current does what to quant and qual?
+ quant, n/a qual
135
kVp/voltage does what to quant and qual?
+ quant, + qual
136
filtration does what to quant and qual?
- quant, + qual
137
Z does what to quant and qual?
+ quant, + qual
138
voltage ripple does what to quant and qual?
- quant, - qual
139
D does what to quant and qual?
- quant, - qual
140
formula btw XR quant and mAs?
I1/I2=mAs1/mAs2
141
formula btw XR quantity and kVp?
I1/I2=(kVp1/kVp2)^2
142
Is XR quant proportional to kVp?
yes, change in quant proportional to the square of the ratio of kVp (if kVp doubled, I increases by factor of 4)
143
formula btw XR quant and D?
I1/I2=(D2/D1)^2
144
formula and aka for direct square law?
density maintenance law; mAs1/mAs2=D1^2/D2^2
145
what is meant by quality?
energy/penetrating ability
146
what is HVL?
thickness of absorbing material necessary to reduce XR I to 1/2 its original value
147
best method to specify XR quality?
HVL
148
total filtration?
inherent (0.5mm Al) + added (1mm Al) + mirror (1mm Al) = 2.5mm Al
149
purpose of compensating filter?
produce uniform density of a nonuniform object aka "wedge filter"
