Midterm Flashcards
1
Q
matter
A
anything that occupies space
2
Q
atoms and molecules
A
fundamental building blocks
3
Q
law of conservation of matter
A
matter cannot be created or destroyed; solid, liquid, or gas mass remains the same
4
Q
energy
A
ability to do work (eV, J)
5
Q
potential energy
A
the ability to do work by virtue of position
6
Q
kinetic energy
A
energy of motion
7
Q
chemical energy
A
energy release by a chemical reaction
8
Q
electrical energy
A
represents the wrk that can be done when an electron moves through an electric potential difference
9
Q
thermal (heat) energy
A
energy of motion at the molecular level
10
Q
nuclear energy
A
energy that is contained within the nucleus of the atom
11
Q
electromagnetic energy
A
energy used in an x-ray
12
Q
law of conservation of energy
A
energy cannot be created or destroyed
13
Q
energy equation
A
e=mc^2
14
Q
radiation
A
energy emitted and transferred through space
15
Q
ionizing radiation
A
any type of radiation that is capable of moving an orbital electron from the atom with which it interacts
16
Q
sources of ionizing radiation
A
natural, man-made
17
Q
What is the highest form of natural ionizing radiation?
A
Radon
18
Q
What is the highest form of man-made radiation?
A
diagnostic x-ray
19
Q
When were x-rays discovered?
A
November 8, 1895
20
Q
Crookes Tube
A
Crookes tube used by Roentgen to discover x-ray
21
Q
What was the first x-ray taken?
A
first x-ray image of Roentgen’s wife’s hand
22
Q
When was the first medical x-ray exam in the United States?
A
February 3, 1896
23
Q
When was the first x-ray fatality?
A
1904
24
Q
Basic radiation protection
A
filtration, collimation, intensifying screens, protective apparel, gonadal shielding, protective barriers
25
collimation
controlling the x-ray beam to only expose the area of interest
26
shielding
lead aprons
27
protective barriers
lead walls surrounding the control console, the x-ray room
28
filtration
remove low energy photons from the x-ray beam to reduce patient dose, typically made of aluminum
29
distance
minimum of 6 feet at a right angle from the patient
30
dosimeters
measure of the level of radiation received by the Technologists
31
ALARA
as low as reasonably achievable
32
exposure
air kerma (Gya), radiation in air
33
absorbed dose
Gray (Gyt), radiation in tissue
34
effective dose
Sieverts (Sv), occupational dose
35
Radioactivity
Becquerel (Bq)
36
Greek Atom
used the term atom meaning indivisible, described the smallest part of the four substances of matter
37
dalton atom
element was composed of identical atoms that reacted the same way chemically, periodic table
38
thomson atom
electrons were an integral part of all atoms, plum pudding
39
bohr atom
electrons in orbits, surrounding protons and neutrons in a dense nucleus
40
What are the fundamental particles of an atom?
electron (negative), proton (positive), neutron (neutral - no charge)
41
Atoms in neutral state
have zero charge, same number of electrons and protons
42
atomic structure
K shell is the closest orbital shell and has the strongest electron binding energy
43
centripetal force
"center seeking," keeps an electron in orbit
44
centrifugal force
"flying out from the center," force that causes an electron to travel straight
45
covalent bonds
chemical union between atoms formed by sharing one or more pairs of electrons
46
ionic bonds
bonding that occurs because of an electrostatic force between ions
47
Radioactivity
the emission of particles and energy in order to become stable
48
radioactive decay law
rate of radioactive decay and the quantity of material present at any given time
49
half life
time required for a quantity of radioactivity to be reduced to one half its original value
50
alpha particles
contain 2 protons, 2 neutrons
51
beta particles
an electron emitted from the nucleus of a radioactive atom
52
gamma rays
emitted from the nucleus
53
x-rays
produced outside the nucleus in the electron shells
54
photons
smallest form of electromagnetic energy
55
at what speed do photons exist?
At the speed of light (c=3x10^8 m/s)
56
wave amplitude
height of the wave
57
frequency
rate of rise and fall; Hertz (Hz)
58
wavelength
distance from one crest to another, from one valley to another or from any point on the sine wave to the next corresponding point; lambda
59
relationship between wavelength and frequency
the shorter the wavelength, the higher the frequency (inversely proportionate)
60
Wavelength
wavelength = velocity/frequency (λ=v/f)
61
Velocity
velocity = frequency x wavelength (v = fλ)
62
electromagnetic spectrum
x-rays, gamma rays, UV light, visible light, radio waves, microwaves, infrared
63
electromagnetic wave equation
c=fλ
64
inverse square law equation
i1/i2 = d2^2/d1^2
65
inverse square law
the further from the source of radiation, the lower the intensity
66
electrostatics
the study of stationary electric charges
67
electrostatic law
unlike charges attract; like charges repel
68
electric potential
electric potential energy (v) - the ability to do work
69
electrodynamics
study of electric charges in motion
70
conductor
any substance through which electrons flow easily
71
insulator
any material that does not allow electron flow
72
semicondutor
material that under some conditions behaves as an insulator an the conditions as a conductor
73
superconductivity
some materials exhibit no resistance below a critical temperature
74
direct current
represented by a straight line, charges are moving in the same direction
75
alternating current
represented by a sine wave, charges are moving in one direction and changing to move in the opposite direction
76
resistor
inhibits flow of electrons
77
battery
provides an electric potential
78
capacitor
momentarily stores electric charge
79
transformer
increases or decreases voltage by fixed amount (AC only)
80
diode
allows electrons to flow in only one direction
81
magnetism
any charged particle in motion creates a magnetic field
82
magnetic permeability
ability of a material to attract the line of magnetic field intensity
83
nonmagnetic
materials that are unaffected when brought into a magnetic field
84
diamagnetic
materials that are weakly repelled by either magnetic pole
85
paramagnetic
materials that are weakly attracted by either magnetic pole
86
ferromagnetic
strongly attracted, can be permanently magnetized
87
electromagnet
current carrying coil of wire wrapped around an iron core, which intensified the induced magnetic field
88
Faraday's Law: The First Law of Electromagnetic Induction
the size of the induced current depends on:
- strength of magnetic field
- velocity of the field as it cuts through the conductor
- angle of the conductor to the magnetic field
- number of turns of the conductor
89
Transformer
changes the intensity of alternating voltage and current
90
step-up transformer
ratio of the secondary coils to the primary coils is greater than one, voltage is increased from primary to secondary
91
step-down transformer
ration of the secondary coils to the primary coils is less than one, voltage is decreased from primary to secondary
92
x-ray imaging system
operating console, high-voltage generator, x-ray tube
93
Operating Console controls
kVp selection, mA selection, Time selection
94
radiation quantity
number of x-rays in an x-ray beam (mGya/mAs)
95
radiation quality
energy of the x-ry beam (kVp)
96
what power does most x-ray imaging systems operate on?
220V power
97
line compensator
measures the voltage provided to the x-ray imaging system and adjusts that voltage to 220 V
98
autotransformer
first to receive power in the imaging system, single winding, supply precise voltage to the filament circuit and high voltage circuit, electromagnetic induction, primary and secondary voltage are directly related to the number of turns of the respective connection
99
filament circuit
controls the X-ray tube current (mA), precisions resistor reduces voltage to a value that corresponds to the selected mA, filament heating isolation step-down transformer
100
exposure timers
located on the primary side of the high-voltage transformer
101
synchronous timers
measured in revolutions, resent after every exposure
102
electronic timers
most accurate, can be used for rapid serial exposures
103
mAs timers
monitors the product of mA and exposure time and terminates when desired mAs is attained
104
automatic exposure control
terminates exposure when the image receptors revolved the required intensity
105
high-voltage transformer
step-up transformer, operate on alternating current, different aptitude between primary and secondary waveforms, primary voltage is measured in Volts (V), secondary voltage is measured in kilovolts (kV)
106
filament transformer
step-down transformer, operate on alternating current, filament needs low voltage and high current
107
rectifiers
allows current flow in only one direction, current supplied is 60Hz, alternating; X-ray tube requires direct current to keep electrons flowing from cathode to anode, silicon - solid state rectifiers
108
single phase power
pulsating x-ray beam
109
three-phase power
waveforms that maintains nearly constant high voltage
110
high frequency generator
nearly constant potential voltage waveform, improving image quality at a lower dose
111
capacitor discharge generator
voltage limits the available X-ray tube current and cause kVp to fall during exposure
112
falling load generator
ensure shortest possible exposure
113
voltage ripple
means of characterizing voltage waveform, less voltage ripple results in greater radiation quality and quantity, most efficient method of x-ray production involves the waveform with the lowest voltage ripple
114
half wave
100% ripple
115
full wave
100% ripple
116
three phase, 6 pulse
13-14% ripple
117
three phase, 12 pulse
4% ripple
118
three phase, high frequency
<1%
119
power
power = current (A) x Potential (V)
