Radiology I Flashcards
1
Q
Radiation is the transmission of energy through space and matter and occurs in what 2 forms?
A
Particulate
Electromagnetic
2
Q
Radioactivity releases alpha or beta particles or gamma rays generated where?
A
Inside the nucleus
3
Q
Oral and maxilofacial radiology involves only what type of radiation?
A
Electromagnetic
4
Q
What type of radiation in the electromagnetic spectrum is capable of ionizing matter?
A
High energy (UV and up)
5
Q
T/F
Electromagnetic radiation is generated when the velocity of an electrically charged particle is altered
A
True
6
Q
The energy of dental x-rays is 60k to 90 k…. (unit?)
A
eV
7
Q
The x-ray tube is surrounded by insulating material, usually what?
A
oil
8
Q
The X-ray tube has electrons stream from the ______ to target the ______.
A
Cathode
Anode
*energy from some e- is converted into x-rays
9
Q
The Filament (the source of electrons within an x-ray tube) is a coil of ______ wire.
The Focusing Cup is a negatively charged concave reflector of ________ surrounding the Filament.
A
Tungsten
Molybdenum
10
Q
The Anode is a ______ target embedded in copper
A
Tungsten
11
Q
The sharpness of an x-ray image ________ as the size of the focal spot Decreases.
A
Increases
12
Q
What type of Radiation primarily emanates from an x-ray tube?
A
Bremsstrahlung Radiation
*German for “braking radiation”
13
Q
Bremsstrahlung Radiation generates x-ray photons with a continuous spectrum of energy and the beam is usually described by its peak operating voltage which is what?
A
70 kVp
*so, fluctuated up to 70
14
Q
The exposure time of an x-ray takes how long?
*time is directly proportional to photon exposure
A
fractions of second
15
Q
The number of photos that reach the patient and image receptor is directly proportional to what 2 things?
A
current (mA)
time (s)
16
Q
Beam quantity/intensity refers to what?
A
Number of photons in x-ray beam
17
Q
What factor is related to the Tube Voltage Peak (kVp)?
A
Quality (meaning energy of x-ray beam)
18
Q
Increasing the kVp of an x-ray increases what 3 things?
A
photons
mean energy of those photons
maximal energy of photons
19
Q
T/F
Low energy photons that can’t reach the receptor still might do damage to the patient and these can be removed by a filter
A
True
20
Q
There is inherent filtration the x-ray passes through like glass, oil, etc. as passes through the machine, but what kind of filter preferentially removes low Energy photons?
A
Aluminum
21
Q
T/F
The Collimator is a metallic barrier used to restrict x-ray size and is Round or Rectangular
A
True
22
Q
The Collimator improves the image quality by decreasing what?
A
Scattered Radiation produced by absorbed photons
23
Q
Describe the Inverse Square Law that applies to x-ray beams.
A
Double distance, intensity of beam is now 1/4
24
Q
X-rays have an Incident Beam, Attenuation, and Scatter - what are the 3 types of Attenuation?
A
Coherent Scatter 7%
Photoelectric absorption 27%
Compton scattering 57%
25
A Coherent Scatter is the change in direction of a photon, a Compton Scatter involved both a ______, like Photoelectric Absorption, and a scattered photon of _____ energy
Recoil Electron
Lower
26
T/F
Different tissues have different Radiosensitivities, so effective dose is a calculation of radiation type and tissue type to determine risk of cancerous formation
True
27
X-rays travel at the speed of light and have no ______ and no ______
mass
charge
28
T/F
| X-rays cause fluorescence and ionization
True
29
T/F
| Males have a higher chance of developing cancer throughout life
True
44% vs 37%
30
Ionizing Radiation is able to remove what?
Orbital e- from atoms
31
Radiation exposure is measured in what?
Roentgen (R)
32
What is used to compare the biologic effects of different types of Radiation?
unit?
Equivalent dose = REM - roentgen equivalent man
Sievert (Sv) = 100 rems
33
T/F
The Effective dose expresses radiation risk to the whole body even though whole body was not exposed and sums the Equivalent dose to each tissue/organ and a tissue weighting factor
True
34
T/F
| The amount of radiation on the skin (Skin Entrance Dose) is the same as the Effective Dose
False
35
The amount of radiation incident on an organ:
Radiation absorbed by tissue:
Biological comparison of different Radiation types on different Tissues:
Organ dose
Absorbed dose
Equivalent dose
36
What dose is used to estimate radiation risks, compares radiosensitivities, weighting factors and is calculated in Sieverts?
Effective Dose
37
T/F
| Salivary Glands are highly Radiosensitive
False
* down around skin
* *bone marrow highest
38
Example of a Direct radiation effect:
Example of an Indirect radiation effect:
alters structure/function of molecule ***(1/3)
water ionization - free radical ionization
39
Indirect Attack causes ____ of DNA damage
2/3
40
The cell killing is Dental Radiography can be described as...
negligible
41
T/F
| The primary risk from dental radiography is the unlikely chance of radiation-induced cancer
True
42
What are the critical organs affected by Radiation?
| 3
Bone Marrow
gonads
Thyroid
43
The Effective Dose, based on tissue type, is measured in what?
Sieverts
44
Deterministic effects are caused by Lethal DNA damage and cell death, while Stochastic effects are based on what?
Gene mutation
*leukemia, thyroid cancer, etc
45
Bone marrow, testes, _____, ______, and _____ are highly radiosensitive organs.
Lymphoid organs
Intestines
Mucous membranes
46
T/F
| Neurons and muscle have Low Radiosensitivity
True
47
Radiation is a weak mutagen and there is no evidence for a dose ______
Threshold
*damage possible at any dose
48
T/F
| Germ cell mutations arising from radiation are possible, but have not been observed in humans
True
*Hiroshima/Nagasaki didn't pass on defects
49
T/F
| Radiation might activate latent carcinogenic viruses or create conditions that favor tumor growth
True
50
The most radiosensitive cells tend to have high mitotic rates, undergo many future mitoses, and are the most primitive in differentiation.
What are the two exceptions?
Small lymphocytes
Oocytes
51
The most radiosensitive tissue is Bone Marrow, what is the least?
Nerve cells
52
Cells are most radiosensitive at mitosis and least sensitive during what phase?
Late S
53
The average energy released from ionization and excitation to absorbing medium per unit track length:
*most widely used term for comparisons of the quality of different radiations
Linear Energy Transfer (LET)
54
X-rays have ___ LET, while Alpha particles and Neutrons have ____ LET
low
high
55
T/F
| High LET radiation tends to generate clustered DNA damage, while low LET radiation creates isolated lesions on DNA
True
56
100 Gy, death in 1 to 2 days by:
10 Gy, death in 5-10 days by:
2-5 Gy, death in 3 weeks by:
cerebrovascular syndrome
GI syndrome
Hematopoietic syndrome
57
2 Gy exposure will result in Transient ______ in hours and last 1 -2 weeks
Erythema
58
focused 10 Gy can result in Dry _______
above 15 Gy ______
Desquamation
Moist Desquamation
59
When during a lifetime is cancer more likely to be fatal?
Early
*changes around 30
60
T/F
| A fetal dose of radiation can double cancer rates
True
61
T/F
| Dental radiographs have a scatter dose to a fetus that is indistinguishable from background radiation
True
*therefore, cannot produce birth defects (this is motivated reasoning, but whatever)
62
Rectangular Collimation can decrease the radiation dose by how much?
90%
63
What is the term that expresses the "one in a million" chance of things?
Micromort
64
Dental x-rays are ___ mrem
NY to Cal flight ___ mrem
background radiation ___ mrem/yr
3
5
300
65
Long plane flight = 1 Micromort
The average man in his 50's has a ____ micromort day risk
Average woman in her 50's has ___ micromort day
2. 1
| 1. 3
66
400 million x-rays taken/year in the US, How many dental?
100 million
67
Of all the Ionizing Radiation a person receives a year in the US about ____ is background and ____ is medical
What % is Dental?
half
half
2.5%
68
Because the effects of ionizing radiation at low doses are not fully understood, what concept is invoked?
ALARA
as low as reasonably achievable
69
What is the Maximum permissible dose of whole body radiation/year?
Lens of eyes?
All other specific areas of the body?
50 mSv
150 mSv
500 mSv
70
T/F
| The MAD - maxi accumulated dose is 10 mSv x Age
True
71
F speed film reduces radiation by:
Rectangular Collimation reduces dose by:
60%
2/3
72
Exposures should use Thyroid Collars and be at w/ _______ kVp
60-70
73
T/F
| The image receptor holding device is more accurate and reduces image retakes
True
74
Aluminum absorbs low energy photons, what absorbs highest and lowest energy?
Rare earth metals
75
T/F
| The focal spot receptor distance can reduce skin dose when moving closer
True
76
What distance should personnel be from the radiation source?
6 feet
*behind lead glass window or mirror
77
Large pts increase exposure time by ___%
Small/child/edentulous pts decrease by ___%
25
30
78
Intensity = 1/D squared
Inverse Square Law
79
What is the Maximum Allowable radiation dosage from diagnostic radiography?
No Limit
80
T/F
| A Lithium fluoride crystal can be used as a Personnel Monitoring Device
True
81
T/F
| Rapid and accurate diagnosis is usually most beneficial to the patient
True
82
The average medium FOV CBCT scan carries a ____ micromort risk
5
83
Potential risk to a fetus is _______
Fetal exposure is entirely ______
childhood cancer
indirect
84
T/F
| Pregnancy is a Contraindication to diagnostic radiography
False
85
Dental radiographic images contribute to _____% of total Exposure from medical imaging
0. 26%
| * despite being 1/4 of all medical imaging
86
5 hr airline flight = 25 uSv or ___ pan and ___ BW's
1 pan
2 BW's
87
Average occupational radiation dose is ___% of allowable exposure
1%
88
T/F
| There are no limits on the exposure a pt can receive from diagnostics, etc
True
89
1 byte = ___ bits
8
90
The grayscale puts black at 0 and white at _____
255
91
The bit scale is:
| bit depth, gray scale
exponential
92
What are the 2 types of resolution in Digital imaging?
Spatial - pixels, dpi, etc
Contrast - how many shades
93
Aside from Spatial and Contrast resolution, the ____ also must have good resolution in digital imaging
Receptor
94
What are the 2 types of Digital Detectors?
Solid State
Photostimulable Phosphor (PSP)
95
CCD and CMOS sensors are what type?
Solid State
96
Intraoral CCD is ____, while intraoral CMOS is ____
wired
wireless
97
T/F
| Extraoral Solid State detectors can be Digital Direct, Panoramic, or Cephalometric sensors
True
98
T/F
| PSP, Photostimulable Phosphor are the same size as film and disposable
False
100% re-usable
99
In Storage Phosphor Technology, the Latent Image produced on the plate goes through what?
***definitely on test
Red Laser Scan
100
The latent image on a ______ can be erased and 100% re-used.
PSP - Photostimulable Phosphor
101
PSP cycle: Acquisition, ______, view, erase, hygiene
Laser Scanning
102
The advantage to CCD/CMOS (solid state) over PSP is what?
Direct image
103
The advantage of PSP over CCD/CMOS are what 3 things?
Film-like
Large exposure latitude
Cheap plates
104
T/F
| Brightness, Contrast, and Gamma adjustment are types of Digital Processing to enhance image
True
105
T/F
| LUT inversio, Color conversion, and Embossing are all considered "toys" and aren't real image enhancement
True
106
T/F
| Resolution is not that important for detecting dentoalveolar disease, contrast and density play a much larger role.
True
107
T/F
| Most systems have more resolution than the human eye can detect
True
108
The Sensor Resolution is ____ Microns (XIOS Plus)
15
109
In X-ray film, the ______ is sensitive to x-rays and visible light, and the _____ supports it.
Emulsion
Base
110
Emulsion is composed of what?
Silver halide/bromide
111
Direct Exposure Film is exposed by X-rays, _____ film is used with intensifying screens and extraoral projections
This type of film is sensitive to what?
Screen film
Visible light (and x-ray)
112
How would you know if X-ray film is loaded backwards?
Lead film on back casts pattern and image is light
113
In an Intensifying Screen, what causes visible light from x-rays?
Inorganic salts/phosphors
114
***The use of Intensifying Screen has what effect on patients?
REDUCES dose of x radiation
115
Developer, water bath, fixer, water, dry
Film processing
116
The _____ converts silver bromide crystals with neutral silver atoms deposited at latent image sites into black, solid silver metallic grains
Developer
117
What removes unexposed, undeveloped silver bromide crystals, leaving the film clear in unexposed areas?
Fixer
118
Light, radiopaque areas means:
Dard, radiolucent areas means:
few photons reached film
many photons reached film
119
Film that is too light can mean what?
Film that is too dark?
underexposed
overexposed
120
T/F
| Spots on film can be from faulty processing, blurred can be caused by pt. movement
True
121
Sharpness can be increased with a small focal spot, increasing distance between _____, and minimizing distance between ______
focal spot and object
object and image receptor
122
Foreshortening can be caused by not aligning with the _____.
Elongation can be caused by not aligning with the ______
tooth (or other object)
film/plate
123
What technique minimizes distortion?
Paralleling
124
In a tube shift or dual image technique what rule determines where objects are in relation to one another?
SLOB
Same Lingual, Opposite Buccal
125
Mesial shift, object moves mesially:
Mesial shift, object moves distally:
Lingual side
Buccal side
126
Eggshell effect:
rim is radiopaque (3D effect)
127
The backbone of imaging for the general dentist is Intraoral Radiographic, what are the 3 Categories?
Periapical (PA)
Bitewing (BW)
Occlusal
128
A Full Mouth (FMX) or Complete Mouth Series (CMS) consists of what?
PA's, BW's, and 18 images
129
T/F
| The use of correct imaging modalities often excludes cone beam CT, etc
True
*used intraoral imaging instead
130
What are the drawbacks to Panoramic imaging?
Resolution
Large field of view
131
What are the drawbacks to cone beam CT (CBCT)?
| 4
Cost
Dose
restoration interference
artifacts
132
T/F
| Overlap can be caused by bad angulation of the Tube Head
True
133
What method may be useful when the operator is unable to apply paralleling technique for whatever reason?
Bisecting Angle Technique
134
T/F
| Position the tube head to the side of the pt that will be radiographed
True
135
The open end of the cylinder must be ____ with the guide ring
Flush
136
What are the 6 Rules for Intraoral Imaging
| (principles of Dental Imaging)?
Receptor completely covers teeth
Vertical sides of receptor parallel with long axes of teeth
Horizontal sided of receptor parallel with horizontal plane of teeth
Open end cylinder parallel with receptor
Central ray enters Proximal Embrasure at 90 degrees
Central ray directed at center of Receptor
137
When are Vertical Bitewings used?
Perio disease
*alveolar crest more apical
138
T/F
Occlusal Radiographs can see more structures, are used if pt can't open mouth, can determine locus, and are limited by receptor size
True
139
What force carrier particle makes up the x-ray beam?
Photon
140
What has greater energy than x-rays?
Gamma
141
Quantum Theory of radiation has been successful in correlating experimental data of what?
Production of X-rays
***polarization, refraction, diffraction all wrong
142
What % of the kinetic energy of e- that hit the anode are converted to heat?
99%
143
Increasing the kVp does what 2 things?
Increases # photons and Mean Energy
144
What is the primary means of dental x-ray attenuation?
Thickness of the mass and energy of the beam
145
What is the most common type of scattering?
Compton
146
When lower energy photons are removed by aluminum filtration, the mean energy ____, and the beam intensity _____.
increases
decreases
147
Deterministic effects have a ______
Stochastic effects have no _____
threshold
threshold
148
What tissue type of the Oral Mucosa is particularly Radiosensitive?
Basal cells
149
In a child, radiation therapy may destroy what (esp if combined with chemo)
Tooth buds
150
If a pt has head/neck therapy avoid intraoral radiographs for how long?
6 months
151
What organ has the lowest susceptibility to induced cancer?
Salivary Glands
152
Most of the radiation the world's population is exposed to comes from what?
Radon
153
Dental x-rays account for less than 1% of the average daily human exposure.
True
154
E/F speed is faster than D speed, what has more quality?
Same
155
State regs require the x-ray beams to be _______ cm or ______ inches to the pts skin surface.
7 cm
2 3/4 inches
156
What size dental films is normally used for adult bitewings?
Size 2
157
How long can a safe light be used in a dark room before it affects the picture?
5 minutes
158
Increasing the focal spot of the film distance does what?
Decreases film density
159
What makes up the Antral Y?
Maxillary sinus and the floor of the nasal cavity
160
What is above the Maxillary molars on a radiograph?
Maxillary sinus
161
A "U" shape on every board exam is what?
Zygomatic process
162
T/F
| The Hamulus will be at the same level as the molars
True
163
Striations through the Maxillary sinus are what?
Blood vessels in lateral wall
164
Ridges on the top of the palate:
Torus palatinus
165
Inferior nasal cavity bone
Inferior turbinate
