Unit tests for final review 2209 Flashcards
(136 cards)
1
Q
Matter is measured in..
A
kilograms
2
Q
Energy is measured in..
A
Joules or electron volt in radiology
3
Q
Atoms and molecules are the fundamental building blocks of..
A
Matter
4
Q
Radio waves, light, and x-rays are all examples of ___ energy
A
electromagnetic
5
Q
A moving object has ___ energy
A
kinetic
6
Q
What is the removal of an electron from an atom called?
A
ionization
7
Q
The biggest source of man made ionizing radiation to the public is
A
diagnostic x-rays
8
Q
In the United States, we are exposed to ___ mR/year of ionizing radiation from the natural environment.
A
20 - 90
9
Q
The basic quantities measured in mechanics are ____, ____, and ____.
A
mass, length, and time
10
Q
Exposure is measured in units of..
A
gray
11
Q
The term atom was first used by
A
the greeks
12
Q
The first person to describe an element as being composed of identical atoms was ___.
A
John Dalton
13
Q
The smallest paricle that has all the properties of an element is a(n) ____.
A
atom
14
Q
The periodic table of the elements was developed by ___ in the late 19th century.
A
Mendeleev
15
Q
Rutherford’s experiments in 1911 showed that the atom was composed of ___.
A
A nucleus with an electron cloud
16
Q
What are the fundamental particles of an atom?
A
proton, neutron, electron
17
Q
An atom in a normal state has an electrical charge of ____.
A
0
18
Q
When an atom has the same number of protons as another, but a different number of neutrons, it is called an ___.
A
Isotope
19
Q
When atoms of various elements combine, they form ___.
A
molecules
20
Q
The shell number of an atom is called the ___.
A
principle quantum number
21
Q
Two identical atoms which exist at different energy states are called ___.
A
Isomers
22
Q
The primary forms of x-ray interaction in the diagnostic range are ___.
A
Compton scatter and photoelectric absorption
23
Q
An incident x-ray interacts with an atom without ionization during ___.
A
Coherent scattering
24
Q
The scattered x-ray from a Compton interaction usually retains ___ of the energy of the incident photon.
A
most
25
As kVp ____ , the probability of photoelectric absorption. ___.
increases, decreases
26
Only at energies above 10MeV can ____ take place.
Photodisentegration
27
K-shell binding energy increases with increasing ___.
Atomic number
28
Only about ___ % of the incident beam contributes to the finished image because of differential absorption.
0.5%
29
The use of contrast agent increases the amount of ___.
differential absorption, compton scatter, and photoelectric absorption
30
High kVp techniques reduce
patient dose
31
What does ALARA stand for?
As Low As Reasonably Achievable
32
Explain the difference between backscatter and secondary radiation.
Backscatter radiation is radiation that is reflected or bounced back in the direction of the incident x-ray beam-this happens outside the patient. Whereas secondary radiation happens during the production of characteristic xrays when an outer shell electron drops into an empty K shell space (inside the patient). The secondary radiation energy is the difference of the 2 shells involved-the one the electron is coming from and the one it is going to.
33
Explain the process of photoelectric interaction. Why is it important to diagnostic imaging? What three things are produced as a result of the photoelectric interaction?
1. Photoelectric interaction is when an incident x-ray is totally absorbed during ionization of an innershell electron. It is absorbed and the K shell electron is ejected from the atom.
2. Photoelectric interaction is important to diagnostic imaging because if the x-ray wasn't absorbed it would not produce the "white" or "light" in the radiograph. But, since it is absorbed, it gives us the "white" or "light" part of the radiograph to produce a diagnostic image.
3. a) characteristic x-rays are produced
b) ionized atom is produced
c) photoelectron is produced
34
The 4 properties of photons are:
frequency, wavelength, velocity, and amplitude
35
The ___ is the unit of electric potential.
volt
36
The charges on an electrified object are distributed ___.
evenly throughout the object
37
What type of material can be made magnetic when placed in an external magnetic field?
ferromagnetic
38
In the United States alternating current goes through a complete cycle every ____ second.
1/60 s
39
The___ of electromagnetic radiation is constant.
velocity
40
Water is a ___ material.
diamagnetic
41
A(n) ___ core increases the magnetic intensity of an electromagnet.
iron
42
The force beween magnetic poles is proportional to the ___ of the magnetic pole strength, divided by the ___ of the distance between them.
Product; square
43
What is the SI unit of magnetic field strength?
tesla
44
The intensity of radiation ___ in ___ proportion to the square of the distance of the object from the source.
decreases; inverse
45
The smallest unit of electrical charge is/are the ___.
electron
46
Photons with the highest frequencies have the ___.
shortest wavelength
47
Gamma rays are produced in the ___ of the atom.
nucleus
48
The velocity of any electromagnetic radiation is
3 x 10^8 or the speed of light
49
Electronic force is ___ proportional to the distance between charges, and ___ proportional to the product of the charges.
inversely; directly
50
Electrification occurs through the movement of ____.
electrons only
51
___ is the eletromagnetic wave equation.
velocity = frequency x wavelength
52
Like charges ____ and unlike ___.
repel, attract
53
The lowest energy range of the electromagnetic spectrum is ____.
radiowaves
54
The diagnostic range of x-ray energy is
30 - 150 kVp
55
The energy of a photon is directly proportional to its ___.
frequency
56
If the intensity of light from a flashlight is 4 millilumens (mlm) at a distance of 3 feet. what will the intensity be at 6 feet?
1 mlm
57
The reduction of radiation intensity due to scattering and absorption is called ___.
attenuation
58
Alternating current is produced by a ___.
generator
59
The smallest quantity of any type of electromagnetic radiation is a(n)
photon
60
Protons tend to interact with matter ___ their wavelength.
equal in size to
61
Electrical power is measured in ___.
Watts
62
A charged particle in motion creates a(n) ___.
magnetic field
63
A hertz (Hz) is equal to ___ cycles per second.
1 cycle per second
64
If the wavelength of a beam of electromagnetic radiation increases by a factor of 2, then its frequency must
decrease by half
65
The mass equivalent of a 100 keV photon of radiation can be calculated using the ___.
relativity formula
66
X-rays are usually identified by their ___.
energy
67
Rubber and glass are ___.
insulators
68
The intensity of radiation on an object is reduced with distance because the radiation ___.
is spread out over a greater area
69
Which of the following is the formula for Ohm's Law?
I = V/R
70
he rate of rise and fall of a sine wave is called its
Frequency
71
An alternating (AC) current is represented by a ___ line
sinusoidal
72
Which of the following is usually coated on the rotating anode?
Tungsten
73
2. Which of the following controls kVp?
autotransformer
74
3. As a x-ray tube ages, the inside can become coated with tungsten, which can cause ___ in the tube.
arcing
75
4. The negative side of the x-ray tube holds the ___.
filament
76
5. Thermionic emission at the filament creates a ___.
space charge
77
6. The source of radiation in the x-ray tube is the ___.
anode
78
7. Which of the following is not a means of dissipating heat in the anode?
a. Conduction
b. Convection
c. Compensation-
d. Radiation of heat
compensation
79
8. When electrons interact with the target, what percent is converted to photons or x-rays?
1%
80
9. The most widely used support structure for the x-ray tube is the ___.
ceiling support system
81
10. A diode allows electrons to flow ___.
from cathode to anode
82
11. The operating console contains circuits that are ___.
low voltage
83
12. The step-up transformer increases voltage___ times
500 - 1000 times
84
13. The high voltage generator contains the high voltage transformer, the ___, and the ___.
filament transformer and rectifiers
85
14. With half-wave rectification, the current flows through the x-ray tube during the ___ part of the cycle.
positive
86
15. The ___ corrects variations in the power distribution to the x-ray unit.
line compensator
87
16. Which of the following is higher for a single-phase than a three-phase generator?
voltage ripple
88
17. The autotransformer has ___ winding(s)
1
89
18. Because of the line focus principle, the focal spot size decreases with decreasing ___.
target angle
90
19. The cathode is part of what circuit?
secondary and filament circuits
91
21. Which of the following is the main parts of an x-ray imaging system?
console, generator, tube
92
22. The ___ circuit provides electrons for the x-ray tube current.
filament
93
23. The ___ is the first component to receive power in the x-ray circuit.
autotransformer
94
24. The automatic exposure control (AEC) terminates the exposure when ___.
Sufficient radiation reaches the IR
95
25. The x-ray intensity is lower on the anode side of the tube because of the ___.
heel effect
96
26. Extra focal or off-focus radiation is produced from ___.
rebounding electrons
97
27. The most accurate kind of timer is the ___ timer
electronic
98
28. The rotating anode is turned by a ___.
magnetic field
99
29. High capacity tubes rotors revolve at ___.
10,000 rpm
100
30. The step-down transformer is located in the ___ circuit.
filament
101
1. Roentgens (grays) in air are the measurement for x-ray ___.
a. Quantity
b. Intensity
c. Exposure
d. All of the above-
All the above
102
2. The number of x-rays in the useful beam defines x-ray ___.
quantity
103
3. Standard x-ray machines produce about ___ mR/mAs at 70 kVp measured at 100cm SID.
5 mR/mAs
104
4. X-ray quantity increases in direct proportions to increases in ___.
mAs
105
5. If the SID is reduced to half its original distance, how is the x-ray intensity affected?
increases times 4
106
6. Changes in ___ result in directly proportional changes in the amplitude of the emission spectrum.
mA and time
107
7. The discrete portion of the x-ray emission spectrum would change position with a change in ___.
target material
108
8. The amplitude of the emission spectrum with a ___ generator is ___ it is with a three-phase generator
single phase; lower than
109
9. A 15% increase in kVp in the 60-80 kVp range is equivalent to ___.
doubling mAs
110
10. How does added filtration affect the emission spectrum?
reduces amplitude and shifts to the right
111
11. The HVL is lowered by a decrease in ____.
kVp
112
12. X-Ray beam quality is improved by ___.
increasing filtration
113
13. The main function of added filtration is to reduce ___.
patient dose
114
14. Added filtration will ___ beam quality and ___ beam quantity.
increase; decrease
115
15. A compensating filter is used to create ___ optical density with a body part of ___ thickness.
uniform; non uniform
116
16. Projectile electrons travel from ___.
filament to target
117
17. During an exposure, most of the ____ energy of the projectile electrons is converted to ____.
kinetic; heat
118
18. At the target, the projectile electrons interact with ____.
a. Outer-shell electrons
b. Inner-shell electrons
c. Atomic nuclei
all the above
119
19. The efficiency of x-ray production is ____ the tube current.
not affected by
120
20. Most of the heat generated at the target is due to ___.
outer shell excitation
121
21. Increasing the mAs 100% is equivalent to increasing the kVp ____.
15%
122
22. If the intensity of a 70 kVp exposure at 20 mAs is 100mR, what would it be at 5 mAs?
25 mR
123
23. If the exposure is 0.5 mGya at an SID of 40 inches, what would be the exposure be at 60 inches?
0.222 mGy
124
24. X-ray intensity is proportional to ____.
kVp^2
125
25. The penetration of an x-ray beam is called x-ray ___.
quality
126
26. The production of heat at the anode is directly proportional to ___.
tube current
127
27. The efficiency of x-ray production increases as ___ increases.
kVp
128
28. Electron interaction at the inner-shell of the target atoms produce ____ radiation.
characteristic
129
29. The quantity of bremsstrahlung radiation increases proportionally with ___.
mAs
130
30. The ___ of an x-ray beam is higher when the peak of the emission spectrum is further to the ___.
quality; right
131
31. An increase in mAs would ___ the ___ of the emission spectrum
increase amplitude alone
132
32. Bremsstrahlung x-rays are produced by ___ at the target.
slowing electrons
133
33. The inverse square law has the same effect on optimal density and x-ray ___.
intensity, exposure, and quantity
134
34. The half-value layer (HVL) of an x-ray beam is a measurement of beam ___.
quality
135
35. If the technologist changes the technique from 70kVp @ 200 mAs to 70 kVp @ 400 mAs, the intensity will ___ and optimal density will ___.
double; double
136
36. At 55 kVp, ___ of the ax-rays produced are bremsstrahlung.
100%
