Final Exam S1 Flashcards
(205 cards)
1
Q
Parsimony?
A
Simple explanations more likely to be true than complex ones
1
Q
Reproducibility
A
Proofs should be able to be duplicated w/ same results
2
Q
Falsifiability
A
Theories should be able to be logically and logistically proven false
3
Q
Observation
A
Proofs should be able to be observed directly w/ the senses
4
Q
Measurability
(results)
A
Results should be able to be measured and mathematically quantified
5
Q
Scientific approach is _________
A
Self-correcting - it will always change
6
Q
When were X-rays discovered?
A
November 8, 1895
6
Q
Who discovered X-rays?
(registry question)
A
Wilhelm Conrad Roentgen
7
Q
Who discovered fluoroscopy?
A
Thomas Edison
7
Q
ALARA stands for?
A
As
Low
As
Reasonably
Achievable
Refers to occupational exposure
8
Q
Largest source of radiation for average human?
A
Radon gas
(coming from earth)
8
Q
Metric system is aka _______
A
Le Systeme International (SI)
8
Q
Unit prefix for hundredths
A
centi = c
8
Q
SI units:
A
Grays, Sieverts, Coulombs/kg2
8
Q
British units:
A
RAD, REM, Roentgen
9
Q
Unit prefix for millions
A
mega = M
9
Q
Unit prefix for thousandths
A
milli = m
9
Q
Unit prefix for millionths
A
micro = Mu
10
Q
2 types of Mechanical Energy
A
Potential energy
Kinetic energy
10
Q
Law of Conservation of Energy
A
Energy can’t be created/destroyed
Energy can only be transformed
10
Q
Unit prefix for thousands
A
kilo = k
11
Q
Potential Energy
A
Energy of position
12
Q
Conduction heat
A
Direct contact
12
Q
Kinetic Energy
A
Energy of motion
13
Convection heat
Mixing of hot & cold molecules
13
99% of X-ray tube interactions are ____ interactions
Heat
14
Radiation heat
Transfer
15
1 reason to use technique charts
Consistency
16
How to determine technique?
Body part
Measurement of body part
17
Proton
Positively charged particle located in nucleus
17
Neutron
No charge particle
located in nucleus
18
Electron
Negatively charged particle orbiting nucleus & creating orbital layers
19
Atomic shells
Letters: K - Q
Principle Quantum Numbers: 1 - 7
2n^2 rule
Octet rule
19
Nucleon
Protons & neutrons
20
Z number
Number of protons in (elements) nucleus
Number of electrons in stable atom
21
Alpha particle
2 protons & 2 neutrons
Changes atom’s elemental structure
20x more damaging than X-rays
(Due to the size)
21
2n^2 rule
Maximum number of electrons allowed in a shell when n = Principle Quantum Number
21
Octet rule
Outermost shell can never hold more than 8 electrons
21
Mixture
2+ substances not chemically bonded
aka Suspension
22
Atomic weight
Slightly higher than number of nucleons
23
Ionic bond
Postive & negative ions attracted to each other electrically
Super strong bond
23
Covalent bond
Bonding of 2 atoms w/odd number of electrons
2 atoms share “extra” electrons in figure 8 pattern
Much weaker than ionic bond
23
Molecule
2+ atoms chemically bonded together
24
Radioactive state
Nucleus is unstable & spends too much energy holding itself together
24
Ground state
Most stable configuration of nucleons
Correct number of neutrons to stabilize atom
24
Beta particle
Breakdown of neutron into positive neutron (now a proton) & high-speed negative electron
5x more damaging than X-rays
24
Isotope
Atom w/ unusual number of neutrons
Not necessarily radioactive
24
Gamma rays
Energy release from unstable nucleus w/o change to atomic structure
Naturally occurring X-rays
25
Ionization
Gain/loss of electron by atom
Creates net electrical charge
(due to addition/subtraction of electron)
25
Ion pair
Ejected electron & its atom
26
2 ways electron can be removed creating an ion?
Incident electron
Incident X-ray
27
How is radiation formed from inner and outer shell electrons?
Inner shell electron is removed from orbit & replaced by outer shell electron
27
Binding energy
Amount of energy used to hold orbital electron in place
Amount of energy needed to knock electron out of orbit
28
keV requirement for electron removal
keV equal to or greater than its binding energy
28
Wavelength
Distance between two like points on wave
Measured in Angstroms
Angstrom = 10^ -10 m
29
Outer shell electron gives off its energy in the form of _____
X-ray
29
Tungsten: M shell
Quantum number & Binding energy?
Quantum #3
Binding energy 3 kV
29
Tungsten Z number
74
29
Test 2 start:
Velocity
How fast energy of wave moves from one point to another
29
Strength of X-ray is equal to _____
Difference between the 2 binding energies
30
Tungsten symbol
W (Wolfram)
30
Amplitude
Maximum displacement of media from its equilibrium
Strength of wave, not its energy
31
Tungsten: K shell
Quantum number & Binding energy?
Quantum #1
Binding energy 69 kV
31
Frequency
Number of cycles passing a fixed point in a second
Measured in Hertz
32
Tungsten: L shell
Quantum number & Binding energy?
Quantum #2
Binding energy 12 kV
33
Electromagnetic wave formula
c = frequency x wavelength
c = speed of light
All electromagnetic waves travel at speed of light (in vacuum)
If frequency increases, wavelength decreases
Energy is directly proportional to frequency
33
Velocity equals ___ x ___
frequency
wavelength
33
Frequency & wavelength have ___ proportional relationship
inverse
34
Energy is directly proportional to ___
frequency
34
X-rays have ___ nature
dual
light photons and physical properties
34
Energy is ___ proportional to frequency
directly
35
Resonance
electromagnetic radiation interacting with substances with similar natural frequency
36
High energies behave like ___
particles
36
Absorption: Light vs. X-ray
Light: yes
X-ray: yes
Low energy X-rays
X-rays that interact w/ radiopaque objects
37
Reflection: Light vs. X-ray
Light: yes
X-ray: no
38
Radiolucent
X-rays can pass easily thru
38
Transmission: Light vs. X-ray
Light: yes
X-ray: yes
High energy X-rays
X-rays that interact w/ radiolucent objects
39
Refraction: Light vs. X-ray
Light: yes
X-ray: no
40
Dispersion: Light vs. X-ray
Light: yes
X-ray: no
41
Attenuation
Partial absorption of light or X-rays
42
Radiopaque
Very few X-rays pass thru
43
Magnetic moment
magnetic field for SINGLE electron or proton
43
Electromagnetism
All moving electric charges develop magnetic fields
43
Magnetic dipole
magnetic field around entire ATOM
(Small)
43
Magnetic domain
Group of magnetic dipoles pointed in same direction
GROUP of ATOMS w/ magnetic dipoles pointed in same direction
43
Ferromagnetic
Iron/nickel materials w/ magnetic domains easily lined up in same direction
44
Paramagnetic
Materials slightly attracted to magnetic fields
Al, O, Au, Cu
44
Diamagnetic
Materials slightly repel magnetic field
Glass, water
45
Retentivity
Ability of magnet to hold on to its magnetism over time
46
Non-magnetic
Materials unaffected by magnetic field
Wood, rubber
47
Strength of attraction/repulsion of poles follows the ___ law
Inverse square law
47
Magnetic fields are strongest near the ___
poles
48
Magnetic field - unit of measurement
Gauss (G) - roughly strength of earth’s magnetic field at the poles
48
Laws of Electrostatics
1. Like charges repel, opposite charges attract
2. Solid objects - only electrons move
3. Solid objects - free electrons only exist on surface
4. Solid objects - free electrons concentrate near point of greatest curvature
49
1 Tesla (T) equals ___ gauss
10,000
49
Electrostatics - unit of measurement
Coulomb
50
Static electricity is generally caused by electrification by ___
friction
50
Typical strength of MRI machine
2 Teslas (T)
50
Electrification
electrons move from one object to another
electrons in both objects is unequal
51
To minimize static, humidity should be above ___
40%
52
Electrification - Induction
charge is induced in another object w/o touching it
52
Electrification - Contact
potential difference exists between 2 objects touching each other
53
Electromotive force - unit of measurement
Volt
53
Electromotive Force (EMF)
Force created by any electric potential difference
54
Electrodynamics - Semiconductors
Electrical current flow in certain conditions
54
Electrodynamics - Conductors
Electrical current flow in most conditions
54
Current flow & electron flow are in ___ directions
opposite
55
Electrodynamics - Current
Flow of loosely-bound outer shell electrons
56
Electrodynamics - Insulators
No electrical current flow
56
Current - unit of measurement
Ampere / Amp
1 Coulomb per second
56
1 Coulomb per second is equal to ___
1 ampere
56
Ohm’s Law:
Formula
V = I x R
Voltage = Current x Resistance
57
Parallel circuit
Each component is connected to power source independently
Failure of one component only breaks circuit to that component, not the others
57
Resistance affected by:
Length, Diameter, Material of conductor
57
Series circuit
Each component of circuit is connected to each other
Failure of one component breaks the circuit
57
Electrical power
RATE at which electrical power is used
57
Resistance
Force preventing electrons from moving thru circuit
57
Electrical power - unit of measurement
Watt (W)
58
At frequency of 60 Hertz, each cycle lasts for ___
1/60th second
58
How many hertz in a second?
60
58
Alternating Current
Oscillation of current back & forth
59
How many pulses in a hertz?
2
59
3 ways to generate alternating current
1.Move conductor back & forth thru magnetic field - most common
2. Move magnetic field back & forth near conductor
3. Alternate the strength of magnetic field
60
Step-down transformer
Voltage goes down
Amperage goes up
60
How many pulses in a second?
120
61
Transformer
Use induction to transform voltage & amperage
61
Step-up transformer
voltage & amperage
Voltage goes up
Amperage goes down
62
True/False
Induction only works with Alternating Current
True
62
Autotransformer
Uses concept of self-induction to slightly change voltage in a circuit
63
What is the Typical incoming line voltage to the high voltage circuit?
220 volts
63
Autotransformer:
makes adjustments to voltage before it is stepped-up
on low-voltage side of the high voltage circuit for safety
63
What is part B in the x-ray machine?
Autotransformer
64
What is part A in the X-ray machine?
Main power switch
&
circuit breaker
65
3 ways the exposure switch and exposure time initiates/terminates
manual timer
mAs timer
Automatic exposure control (AEC)
65
What is part C in the x-ray machine?
Exposure switch
&
exposure timer
66
What is part D in the x-ray machine?
kVp Meter
(parallel circuit)
67
What is part F in the x-ray machine?
mA meter
(series circuit)
68
What is part E in the Xray machine?
Step-up transformer
turn ratio 500:1 to 1000:1
68
What is part H in the x-ray machine?
x-ray tube
thermionic emission- cathode (-)
x-ray production- anode (+)
69
Autotransformer (step?):
B
adjusts voltage before stepping up
69
What is part G in the x-ray machine?
Rectification bridge
(changes alternate to direct current)
69
What is part I in the x-ray machine?
Rotor switch
anode spin at 3400 RPM
heats up the filament
boils off electrons from filament due to high amps and high resistance
70
Main power switch and circuit breaker (step?):
A
Typical incoming line voltage is 220V
70
What is part J in the Xray machine?
mA selection
(resistors)
70
What is part K in the x-ray machine?
Step Down Transformer
ratio 1:44
up to 5 amps
71
Exposure switch and time (step?):
C
initiates exposure and terminates 1 of 3 ways:
Manual timer
mAs Timer
Automatic exposure control (AEC)
71
Step-up transformer (step?):
E
turns ratio 500:1- 1000:1
71
Kvp Meter (step?):
D
measures the Kvp
(parallel)
71
Rectification bridge (step?):
G
Diode changes alternate to direct current
electrons approach “n” side,
electrons are repelled towards bridge
p is positive side that repels holes toward the bridge
72
mA meter (step?):
F
Measures the amount of mA
(series)
72
rotor switch (step?):
I
spins anode 3400 rpm
heats up filament in the x-ray tube
thermionic emission due to high amperage and high resistance
72
x-ray tube (step?):
H
thermionic emission (cathode)
x-ray production (anode)
73
mA selection (step?):
J
Resistors
more resistors less amperage (vice versa)
73
Step down transformer (step?):
mA increased by:
K
ratio of 1:44
mA is increased by a factor of 44, up to 5 AMPS
73
Ch 9: xray tube
Cathode:
negative side of the x-ray tube
Thermionic emission
74
Half wave/self-rectified circuits
60 pulses a second
100% voltage ripple
30% average Kvp
74
Thermionic emission:
“BOILING OFF” electrons from filament due to high amperage and high resistance
75
Filaments are made up of:
thorium-impregnated tungsten
thorium z=90 helps with heat tolerance
75
single-phase/ full wave rectified
120 pulses a second
100% voltage ripple
30% average Kvp
76
3 phase/ 6-pulse generators
360 pulses per second
14% voltage ripple
91% average Kvp
76
3-phase/ 12-pulse generators
720 pulses per second
4% voltage ripple
97% average Kvp
76
high frequency generators
greater than 500 pulses
per second 500<
1% voltage ripple
100% average kvp
hz is altered from 60 to 500-25,000 HZ
77
Ch 9: xray tube
How many filaments in x-ray tube?
2 filaments
small= 1 cm
large: 1.5-2 cm
77
What does focal spot do?
Small?
Large?
smaller focal spot creates sharper images
large focal spot better for high heat x-rays (L-spine)
78
what is heat units for?
(What does it measure)
to measure how much heat the anode can withstand
(a unit of measurement for anode heat capacity)
78
Thermionic emission occurs in the:
What is thermionic emission?
Cathode
“boils off” electrons from the filament due to high current flow and high resistance
78
Focusing cup:
What is its charge?
Negative charge
prevents electrons from rushing away by surrounding the filament (negative focusing cup narrows the electrons due to the law of attraction)
79
focal spot (in anode) is _% of filament?
5%
(0.5mm-1mm)
79
Focal spot for hands/feet x-rays:
Small focal spot
1cm
79
What is space charge?
electron cloud forms around the filament when the rotor button is pushed
80
mAs directly controls the number:
of x-rays that exit the tube
80
Doubling mAs will:
double the amount of x-rays created
80
Target:
A part of what?
Made of what?
area of the anode disk that is struck by the electrons
made of tungsten and rhenium z=75
80
focal spot for lateral lumbar:
large focal spot
1.5cm to 2cm
80
Anode:
positive side of the x-rays tube
Xray production
81
What is struck by electrons in the x-ray tube?
the target in the anode (anode disk)
very durable to high amounts of heat
81
Rotor:
A part of what?
Anode
Connects the shaft and spins when influenced by the stator (induction)
81
What is arcing?
vaporized tungsten coats the inside of the tube
type of short circuit:
1. cracks the glass
2. eliminates vacuum
3. burns out the filament
82
Main cause of x-ray tube failure?
arcing
82
What is a way we can protect the x-ray tube?
(3)
1. warm up procedures to prevent thermal shock (hot water on cold glass=crack)
2. avoid excessive rotoring
3. calculate the heat units to prevent overheating of the anode
83
What is the anode cooling chart purpose?
how long will it take for the anode to cool before making another exposure
83
What is the purpose for a tube rating chart?
to ensure that a technique will not exceed the heat capacity of an x-ray tube
83
HU (heat units) formula:
1.4 (constant/ don’t forget)
x
kVp
x
mA
x
s (seconds)
83
heat interactions:
99.5% of interactions at 60 Kv
99% of interactions at 100 kv
83
bremsstrahlung is responsible for the:
vast majority of x-rays
83
stream of electrons:
How fast?
using the voltages in x-ray electrons can accelerate at 1/2 the speed of light in just one inch
84
Bremsstrahlung:
“braking radiation”
interactions with the nucleus
84
Characteristic:
projectile electron from CATHODE interacts with INNER shell electron
it can be ejected
84
In Bremsstrahlung what is the average kv exiting?
(The avg kv after filtration is 1/3 of kvp setting)
the average KV exiting the x-ray tube after filtration is about 1/3 of the kVp setting
84
Any _____ can fill the vacancy in an inner shell electron, including ____ _______ outside the atom in characteristic
Electrons
Free electrons
84
Characteristic cascade:
Inner shell electrons are replaced in sequence (k by L,L by M, M by N,N by O).
MULTIPLE x-rays are created
84
What are the steps of characteristic?
1. electron interacts with inner shell electron
2. outer shell electron will drop down to fill the vacancy (L to K)
3. The strength of the x-ray is equal to the difference between the two shell electrons
85
Filtration removes what kind of x-rays?
adding more filtration will:
Filtration removes weak x-rays
&
adding more filtration will remove even more weak ones
Increasing the average kvp
85
The result of characteristic cascade is x-rays at _____ _________
Specific energies
K shell- 57, 66, 68, 69 KV
L shell- 9,11,12 KV
85
(T/F)
when the Bremsstrahlung spectrum and characteristic spectrum are combined we have a complete graph of all the x-rays leaving the x-ray tube
True
86
What are factors that affect the x-ray emission spectrum?
1. Target material (mammography)
2. Milliampere-seconds (mAs)
3. added filtration
4. Kilovoltage-peak (kVp)
5. generator type
(3 are of these are most common/ I think 2,3,4)
87
Increasing the kVp will move:
the x-ray emission spectrum to the right due to the increase energy from x-rays
88
When we filtrate more x-rays what happens to the average KV?
What is this known as?
the average KV will go up
this is known as “hardening” the x-ray beam
89
How do generator type play a role in x-ray emission spectrum?
mostimportantly the average kvp
Changes the pulses, voltage
ripple, average kvp
(high frequency, single phase, etc)
90
How does target material play a role in the x-ray emission spectrum?
(won’t be tested much on)
(Certain material will lower the average kvp)
like in mammography the material of the target will affect the average KV
(ex: in mammography avg is 17 KV)
91
Average KV after exiting the x-ray tube after:
filtration is about 1/3 of the kVp setting
91
therionic emission
a “boiling off” of electrons from the filament due to high current flow and high resistance
92
Hardening the x-ray beam:
adding more filtration for weak x-rays
thus increasing the average kVp
92
At the bridge current:
can flow
92
(T/F)
free electrons outside of the atom can fill the vacancy of the inner shell?
True
ANY electron
