Radiology Flashcards
1
Q
Periapical Radiograph should record the?
A
Crown, Root and periodical area. Shows 2-3mm periapical area
2
Q
The Definition of Radiolucent is
A
Dark or Black area on the radiograph
3
Q
Radiolucent could be seen as
A
Air, Soft Tissue, Pulp Canal, areas of Bone Loss
4
Q
The Definition of Radiopaque is
A
Light or White area on the radiograph
5
Q
Radiopaque could be seen as
A
Enamel, Dentin, Metal Restorations Endo fillings, Bone
6
Q
Two Types of Radiographs
A
Intraoral and Extraoral
7
Q
What are the two reasons for Bitewings?
A
Alveolar Crest Bone Level, and proximal Caries
8
Q
Extraoral Bitewing
A
New Technique: one image for each side of jaw, uses PAN- Therefore extra oral imaging. Records periodical areas
9
Q
Topographical shows
A
wide coverage of bone pointing towards note
10
Q
Cross Sectional shows
A
Buccal or lingual localization
11
Q
What is the line that represents an imaginary center of x-ray beam?
A
Central Ray
12
Q
Supernumerary is
A
An extra tooth
13
Q
Why is intraoral preferred over Extraoral?
A
A structure or lesion can be recorded entirely on intraoral
14
Q
Why do we use extraoral?
A
Disease can’t be covered by intraoral so we use extraoral
15
Q
Trismus means
A
Inability to open mouth
16
Q
Periapical or Bitewing radiographs provide the maximum _________
A
Detail
17
Q
When area to be radiographed is larger than can be covered we use ________________
A
Extraoral Radiograph
18
Q
Why do we use extra oral radiography?
A
Disease is located in an area not normally covered by intraoral films, also used for patients who gags on intraoral film
19
Q
Focal Trough
A
Grey shaded area or area of focus
20
Q
The pan records:
A
Unobstructed, panoramic records of entire mandible, maxilla and associated structures on single radiograph
21
Q
The pan is the most ______________ extra oral radiograph in dentistry
A
common
22
Q
Cephalometric is used to
A
measure and assess growth
23
Q
Cephalometric has a fixed ___________ to ___________ Distance of ______in
A
Source to film distance of 60 in.
24
Q
Cephalometric Radiography has
A
the most standardized and reproducible views
25
Who is the first person in the world to take a dental radiograph?
Otto Walkhoff
26
In a few sentences, write what inventions led to the discovery of x-rays in 1895?
Three major inventions paved the way for the discovery of x-rays. These are 1) photography and photographic plates, 2) electricity, and 3) light bulbs. Modification of the bulb and energizing the bulb with electricity produced x-rays. These rays were recorded on the photographic plates.
27
Q5. Unit 1. What was the problem with nitrocellulose films that prompted the development of polyester films? The nitrocellulose films used to
Catch Fire
28
Which dentist was a pioneer in alerting that radiation was dangerous?
William H. Rollins
29
Radithor was:
A mix of radium and water
30
What type of image does not use ionizing radiation
MRI
31
What are the three types of intraoral radiographs?
Intraoral, Bitewing, and Occlusal
32
What kind of imaging is a standardized radiograph for measurements?
Cephalometric
33
The purpose of cross-sectional occlusal radiography is identifying
the buccal or lingual location of an object
34
What kind of images provide the maximum detail?
Intraoral radiographs
35
The A number (Atomic mass number) of an atom means the total number of
Protons and Neutrons
36
The word ionization means
To Create and Ion Pair
With the loss of an electron (negatively charged), the atom becomes positively charged. The process of creating this pair of positive and negative ions is called ionization. The answer is on page 23 of the handout.
37
An Electron is positive or negative charge?
Negatively Charged
38
What is Binding Energy?
The binding energy is the force that keeps the electrons in their own orbits. An electron on the inner shell has higher binding energy. The outer shell electrons have lower binding energy. Therefore, it is easier to remove an outer shell electron than an inner shell electron
39
According to Bohr’s model, what is the maximum number of shells or orbits in an atom
Seven
40
The Z number (Atomic number) of an atom means the total number of
Protons
41
What kind of electromagnetic radiation has stronger energy?
Short Wavelength
42
Which Electron has higher binding energy?
Inner Shell Electron
43
What is the charge of a Neutron?
No Charge
44
Of the following radiation, which one has the shortest wavelength?
x-rays
45
Which is the most common interaction of photons with matter
Compton scattering
46
How long does radiation stay in the room after radiographic exposure?
Radiation Does not Stay after exposure
47
During ionization, what is lost from an atom?
The Electron
48
In Comptons Scattering, which electron is ejected?
The Outer Shell
49
During the interaction of x-rays, an atom underwent excitation. What happened to the atom?
No Loss of the Electron
50
In your clinic, the x-ray machine makes a beeping sound during exposure. How loud is the x-ray?
The X-ray has no sound
51
Which interaction requires more energy
Photoelectric absorption interacts with an inner shell electron. The inner shell electrons have higher binding energy.
52
What is the role of a step-up transformer?
To multiply the incoming voltage
53
What is the unit of current?
apmere
54
What kind of terminal is a cathode?
Negative
55
What is the unit of Voltage?
Volt (v)
56
What is the unit of resistance?
Ohm
57
What kind of energy are you using on your cell phone on your hike in the mountains?
(Direct Energy) During your hike, your cell phone is still using electricity. But the phone is not plugged into the wall. The electricity is coming from the battery. The electricity of the battery is from a DC generator. Please see the answer on page 13 of the handout. When your phone is connected into the wall outlet, you are using alternating current, which is converted into DC through the cell phone battery)
58
What is the Quantum Model
Positive Charged nucleus at the center, Negatively charged electrons are in 3 dimensional orbitals
(No More than 7 orbits) Orbitals shapes are spherical or lobular.
59
Bohr Model
shows the atom as a central nucleus containing protons and neutrons with the electrons in circular orbitals at specific distances from the nucleus
60
An AC generator makes a 60-cycle current. What does this statement mean?
Its flow has 60 peaks or troughs per second
61
Electrons are arranged in definite energy levels know as
orbits or shells
62
Orbits are at varying ___________.
distances
63
Orbits are in alphabet or numbered as
K,L,M,N,O,P,and Q or 1,2,3,4,5,6,7
64
How Many electrons in each shell?
2n(squared) +2x(orbit number) Squared
65
Ionization is
Neutral atom loses an electron, the atom becomes positively charged.
66
Radiation
Transfer of energy through space and matter
67
Ionizing Radiation is:
Radiation that causes ionization.
68
What are the two types of Radiation:
Particulate and Electromagnetic
69
Particulate Radiation is described as:
Particulate Radiation transfer of energy by high velocity subatomic particles. When Particulate radiation passes through any matter, it loses some energy.
70
The Loss of Energy in Particulate radiation is called
Linear Energy Transfer
71
______________ Radiation comes from subatomic particles
Particulate Radiation
72
Electromagnetic Radiation is described as:
Waves of Energy (Transfer of energy through space as a combination of electrical and magnetic fields. )such as : Gamma Rays, X-rays, ultraviolet rays, visible light, TV, radar and microwave.
73
Electromagnetic Radiation has two theories called:
Wave Theory and Quantum Theory
74
Wave Theory
Energy is transferred in the form of waves
75
Quantum Theory
Electromagnetic radiation is considered as "bundles" of energy called photons
76
Wavelength
Distance between two successive crests or troughs
(Measured in meters or in case of X-rays Angstrom Units)
77
Long wavelengths have ____________ Energy
Low
78
Short wavelengths have ___________ Energy
Strong
79
Light waves that have same color (energy) are _______________
Monochromatic
80
Light waves that have different colors (energy) are _____________
polychromatic
81
EMR Wave Theory states that:
Not all light waves/xray waves have same energy
82
Excitation is
When the transferred energy is not sufficient to overcome binding energy. Electron is not ejected, but the receiving electron is raised to a higher energy level within the orbit.
83
Photographic Effect
84
What is the primary type of radiation produced in a dental x-ray machine?
Bremsstrahlung
85
The role of a low voltage circuit in an x-ray tube is to
Increase the temperature of the cathode components
86
A 60-cycle x-ray machine means
The x-ray production turns on and off 60 times a second
87
What is the main risk of high temperature in an x-ray machine?
The filament may disintegrate
88
In bremsstrahlung radiation, the interaction is
Electron from the cathode interacts with the nucleus of the anode
89
A step Up transformer is added to the X-ray machine to
modify the penetrability of the x-ray beam
90
The Duty Cycle is for:
The duty cycle is for minor exposures, for fractions of seconds. For panoramic radiography, we have a longer single exposure. Therefore, the concept of duty cycle is not relevant for panoramic radiography. Although tube rating is mostly for research or investigative purposes, for a long panoramic exposure, tube rating is more important than duty cycle. Please review the concept on pages 25 and 26 of the handout.
91
In characteristic radiation, the interaction is
Electron interacts with an inner shell electron
92
What is the primary factor in an x-ray machine that controls the quantity of x-rays before the beam exits the tube head?
Milliampere
93
Why does a radiographic image become darker if you increase the mA?
More x-ray beam reaches the sensor
94
After an x-ray exits an x-ray tube, what factor affects the quantity of x-ray?
Filtration
(kilovoltage, milliampere, and time of exposure are factors related to the x-ray tube. After the x-ray beam exits the tube, only filtration will affect the quantity of x-rays reaching the patient’s body. By filtering, we remove the less penetrating x-ray photons. Therefore, a large quantity of radiation reaches the patient’s body)
95
What kind of radiation should be the primary concern for the well-being of a dental assistant?
Scatter (the scatter radiation can travel in any direction and leads to a unnecessary exposure of the operator)
96
The purpose of filtration is to
Reduce the radiation dose Filtration removes low energy photons. These photons do not contribute to the image formation and unnecessarily exposes the patient. Therefore, using filtration, we reduce the radiation dose to the patient)
97
Your radiographs are coming out lighter than the desired diagnostic quality. The settings for kVp and mA are fixed and cannot be changed. What can you do to improve the density of the radiographs?
Increase the exposure time
98
The main purpose of selecting a greater collimation is
Reduce the exposure to the body parts (collimation is to reduce the size of the x-ray beam. With greater collimation, a smaller part of the body is exposed to radiation)
99
If you increase kVp, what happens to the x-ray beam?
The beam can cross thicker tissues (kVp primarily controls the quality or penetrability of the radiation. With higher kVp, the more energetic radiation beam can cross thicker tissues)
100
How can a Dental Assistant benefit from following the principle of inverse square law?
Unnecessary exposure to the operator can be reduced
101
You are purchasing a new intraoral x-ray machine. In the space below, please write an accessory that can you select to reduce the radiation dose to the patient? Please provide the answer based on the knowledge from this unit.
Most x-ray machines, with a round collimation. If you buy a rectangular collimation (rectangular PID) the radiation dose to the patient will be significantly smaller. I asked you to answer based on knowledge from this unit. The concept is presented on pages 14-16 of the handout of this unit. In a future unit, in unit 24, page 11 of the handout, we will see that FMX with round collimation provides a dose of 85 microSievert, while a rectangular collimation has a dose of only 17 microSievert. This is a significant drop
102
Your x-ray machine has fixed kV and mA. The only modification allowed is the number of pulses of x-rays. Please indicate how you will adjust the settings for the following types of patients? After radiographing a 10-year-old child, your next patient is a Viking Quarterback
Increase the pulse
103
Your x-ray machine has fixed kV and mA. The only modification allowed is the number of pulses of x-rays. Please indicate how you will adjust the settings for the following types of patients?After radiographing a 30-year-old man, your next patient is an 83-year-old grandmother
Decrease the Pulse
104
Your x-ray machine has fixed kV and mA. The only modification allowed is the number of pulses of x-rays. Please indicate how you will adjust the settings for the following types of patients?After radiographing a 30-year-old man, your next patient needs a complete denture
Decrease the Pulse
105
Your x-ray machine has fixed kV and mA. The only modification allowed is the number of pulses of x-rays. Please indicate how you will adjust the settings for the following types of patients? Your machine had 3 mm Aluminum filter. Your technician replaced the filter with a 4 mm aluminum disc. To get new radiographs with the same density, what step would you take?
Increase the Pulse
106
Your machine allows adjustment of mA and time. For an ideal exposure, you need 10 mAs. In the spaces below, write what adjustment you will consider for the following patients: A restless child: You have set the exposure time to 1 second. What will be the correct mA for an ideal exposure?
10 mA (10 mA x 1 second = 10mAs)
107
Q25. Unit 8.. Your machine allows adjustment of mA and time. For an ideal exposure, you need 10 mAs. In the spaces below, write what adjustment you will consider for the following patients: A high school senior. You have set the exposure time to 2 second. What will be the correct mA for an ideal exposure?
5 mA (5 mA x 2 seconds = 10mAs)
108
Your machine allows adjustment of mA and time. For an ideal exposure, you need 10 mAs. In the spaces below, write what adjustment you will consider for the following patient: A patient with Parkinson’s disease. You have set the exposure time to 0.5 second. What will be the correct mA for an ideal exposure?
20 mA (20 mA x 0.5 second = 10mAs)
109
Your machine allows adjustment of kVp, mA, and time. For an ideal exposure at 60 kVp, you need 10 mAs. If you increase the kVp to 70, how would you adjust the time of exposure?
Decrease the pulse
110
Your machine allows adjustment of kVp, mA, and time. For an ideal exposure at 60 kVp, you need 10 mAs. At 60 kVp, you have selected 5 mA. What should be the exposure time?
2 Seconds
111
The slanting of the anode is to
Assist in the line focus principle
112
Why is tungsten used as a filament material?
Tungsten has a high insulating property
113
What is the purpose of oil surrounding the glass tube?
Provide a temperature control to the tube. (during x-ray production, the x-ray tube generates high heat. The oil surrounding the tube helps in cooling the tube. The answer is on page 5 of the handout.)
114
The cathode component has which of the following features?
Negatively charged with a tungsten filament
115
The role of focusing cup in an x-ray tube is to
direct the electrons to the focal spot (The negatively charged focusing cup focuses the electrons in an narrow path towards the anode. The concept is described on page 8 of the handout.)
116
Which of the following choice(s) has lower thermal conductivity
Tungsten
117
Nucleus has:
protons and neutrons (positively charged)
118
Hydrogen Atom has
single proton and a single electron
119
When Matter changes _____________ is ___________
energy is formed
120
What is one of the benefits of panoramic radiography over FMX?
Lower Radiation (Although panoramic radiography has several advantages over FMX, from the above choices, the lower radiation dose would be the correct answer)
121
In panoramic radiography, why do machine components move?
to select a specific tissue layer
122
Since panoramic radiography is a type of tomography, the selection of the tissue layer is obtained by moving the x-ray tube and the sensor in opposite direction.
To select a specific tissue layer
123
In panoramic radiography, what is a focal trough?
Areas that have objects of interest
124
In panoramic radiography, collimation is done to
to generate a narrow beam
125
DICOM is a term that applies to
DICOM is for all kinds of digital medical images. The film based radiography is not included because these are not digital.
126
1. How does the beam shape of the CBCT differ from a panoramic x-ray beam?
Panoramic radiography uses a narrow x-ray beam. CBCT uses a cone-shaped beam
127
What is the full form of MPR
Multiplanar Reconstruction
128
Excitation is when Transferred ___________ is not sufficient to overcome _______________, electron is not ejected
Excitation is when transferred energy is not sufficient to overcome binding energy, electron is not ejected.
129
What is the difference between pixel and voxel?
Pixel is a 2D image while a Voxel is a 3D image
130
What does Field of View mean as related to CBCT scans?
The field of view describes the amount of tissues included in a CBCT or a CT scan. The concept in different sizes of field of view
131
If you can adjust MA, when you increase mA the image is
Image is darker
132
If you can adjust mA, you decrease mA the image is
Image is lighter
133
If you can increase (mA)
decrease the time
134
If you can Decrease (mA)
increase the time
135
What controls the number of electrons and controls the quantity of radiation
Milliampere
136
KvP is
Energy of the X-ray beam (controls quality)
137
What is the function of aluminum filter?
in charge of filtering the good X-ray beams.
138
What are the different types of 3D rendering for CBCT images
Solid surface rendering and semi transparent rendering
139
How do we control the size and shape of the X-ray beam?
Through Collimation
140
How can you identify if a CBCT scan has motion artifacts
Primarily, by identifying double outlines of the borders of the bone. Sometimes motion artifacts will also create streaking.
141
xray beams that is coming or exits from the tube head
Primary Radiation
142
This happens when the primary radiation interacts with patients tissue ( Soft tissue, teeth, bone)
Secondary Radiation
143
This falls under type of secondary radiation, and is deflected from the original path and ravels in any direction:
Scatter Radiation
144
The problem with secondary (scatter) Radiation
unnecessary exposure to the patient
145
Any Radiation that comes out of the X-ray tube head other than the primary beam is called:
leakage Radiation (originates from faulty tube head)
146
how does second generation of CT differs from the first generation?
he first generation CT had only one detector. On the 2nd generation CT, multiple detectors were introduced.
147
What element is most important for creating MRI?
Hydrogen (MRI uses hydrogen atoms in our body to create an image)
148
Amount of radiation per second is defined as:
Exposure Rate
149
If X-ray is produced in 60 cycles per second, each cycle is called
Impulse: 1 sec. = 60 impulse
1/2 sec.= 30
1/4 sec.= 15
1 to 60
150
Exposure time and mA are inversely
related
151
In the space below, write the name of a radiographic examination for salivary glands.
A common technique for salivary gland imaging is sialography
152
for constant radiographic density, exposure time and Kvp are inversely
related
153
When KvP is increased, exposure time should be ________________
Decreased
154
What does a Hounsfield Unit represent
Densities of tissues on CT voxels
155
What is the meaning of Windowing for CT?
Selecting a range of densities of tissues on a CT image. (Windowing is to view selected gray shades of the tissues on a CT scan)
156
What is the distance between the x-ray source and receptor for a cephalometric machine?
60 in.
157
A radiofrequency pulse is employed to change
the orientation of protons in a tissue
158
Tesla is the measurement for:
the unit for measuring the strength of a magnet
159
In processing PSP plates, what information is collected by the computer? The amount of
Visible Light (in processing PSP plates, a laser beam is used. The crystals of the PSP plates emits visible light. The visible light is multiplied and the computer identifies the amount of the visible light.)
160
For faster image processing, which is the best technology?
CMOS (CMOS and CCD are direct imaging technology. CMOS is faster than CCD. The conventional analog films and PSP plates require processing, which takes time.)
161
For analog films, what is the main component of the coating
Silver Bromide
162
For CCD sensors, what is the principle of data collection?
Electrons move from one pixel to another
163
What imaging technology employs the bucket brigade concept?
CCD
164
What is the benefit of rectangular collimation
While using the same type of image receptor, rectangular collimation decreases radiation dose by at least 50%
165
why you should process PSP plates as quickly as possible?
Room temperature can release trapped electrons in a PSP plate, degrading the data. Therefore, PSP plates should be processed as quickly as possible.
166
Which factor is more important for identifying a hairline fracture of a root?
Spacial resolution:
Spatial resolution is for identifying fine details, e.g., fine lines or hairline fractures.
167
Which factor is more important for identifying dental caries?
Contrast resolution: Extent of caries is determined by different densities of normal and diseased tooth structure.
168
What is the purpose of a dot on an intraoral film?
Identifying radiographs from the right or the left side
169
What is the purpose of a lead foil in an introral film packet?
Reducing scatter radiation
170
What is the error that caused a dark spot on a processed radiograph?
Contamination of the film with the developer before fixing
Remember D for dark spot, and D for developer. Once a film has been fixed, developer will not change chemical composition of the crystals.
171
A processed radiograph shows tire track marking. What does this mean?
(The film packet was reversed during exposure)
The tire track markings appear from the lead foil. If the film packet was reversed during exposure, the imprints of tire track on the lead foil will be recorded on the film.
172
What is the correct sequence of film development?
Developing followed by fixing
173
What is the error that caused a white spot on a processed radiograph?
Contamination of the film with the fixer before developingRemember white or fair for fixer.
If a film is contaminated with fixer before developing, it will have a white spot.
174
why is only one surface of the film packet is colored?
The color on the film packet is to remind us that the white side must face the radiation.
175
what does ‘definition’ mean for a radiographic image
In radiology, definition means the sharpness of a structure as recorded on the image. A well-defined structure has a sharp border. A poorly defined structure has fuzzy border.
176
what does ‘distortion’ mean for a radiographic image.
In radiography, distortion means unequal magnification of a structure. Some areas of the tooth is magnified in some area is less magnified. A distorted image does not represent the true shape of the anatomy.
177
Which of the following radiographs employ the maximum positive vertical angle (+VA)?
Maxillary incisor
178
Which of the following radiographs employ the maximum horizontal angle?
Molar
179
Why do we not use bisecting angle technique
n angle bisecting principal, the correct geometry is difficult to obtain as the x-ray beam is invisible and the bisecting line is also imaginary. On the properly recorded image with bisecting angle, the vertical dimension is correct but the image is somewhat distorted. If a mistake is made, there will be foreshortening or elongation.
180
One geometric factor that will increase the size of the penumbra of the radiographic image is a:
decreased source to film distance (film-object distance is constant) This concept is important for using a long cone (PID). A short will create images with wider penumbra, which means with more fuzziness (less defined).
181
On a periapical radiograph, which object is magnified more?
Buccal (An object further away from the receptor is only is magnified more than the object closer to the receptor)
182
On a panoramic radiograph, which object is magnified more
Since the panoramic radiographic receptor is outside the mouth, objects the lingual surface would be magnified more.
183
List at least four different ways that you may localize an object in a patient’s mouth using radiography.
image shift principle, right angle technique, cross sectional occlusal radiography, ct, Sri, other cross sectional studies.
(The four different ways of localizing an object are, 1) image shift principle, 2) right angle technique, 3) cross-sectional occlusal radiography, and 4) CT or MRI. In addition, we may also employ panoramic radiography to help localize a structure depending on the size of the object.)
184
A structure appears highly radiopaque on a periapical radiograph. This structure is/has
absorbed more radiation
The density of an structure depends on how much radiation can pass through the object.
185
Your patient is a 260 lb football player. What should you do to get a good quality image?
Increase the PulseLarge patients have more tissues. This creates more attenuation and more scatter. These patients will require increased exposure, which can be achieved by increasing mA or the pulse.
186
A structure appears highly radiolucent on a periapical radiograph. This structure is/has
low chemical density
Tissues that allow more radiation to pass through will be radiolucent. Such tissues have low chemical density.
187
A radiograph appears ‘washed out’ or light. Your machine does not allow any modification of kVp or mA. What can you do to make the subsequent radiographs darker?
Increasing the time of exposure will improve the density of the radiograph.
188
Which of the following materials will appear most white or light on a radiograph? Gutta core, enamel, gold crown, or composite restoration?
Gold Crown
189
What factor of a gutta percha root canal filling makes it whiter than a composite filling on a radiograph?
Chemical Composition
190
In your x-ray unit, an ideal periapical radiograph of the molars requires ten pulses. By mistake, you increased it to 20 pulses. How would your image look like??
too dark (Increasing the pulse will increase the density of the image. Therefore, the image look too dark)
191
Your patient has a large mandibular torus. A torus is a dense bony growth (we will learn about torus in a disease lecture). What adjustments can you make to get a radiograph of good density? Your machine has fixed kVp.
Since our machine has fixed kVp, we may increase the exposure by increasing mA or pulse to get a diagnostic image. This concept is similar to taking radiographs on a large patient.
192
Your patient has many carious teeth and some faulty restorations. What kind of image contrast will you prefer?
Moderate
193
Your patient has many carious teeth and some faulty restorations. What kind of image contrast will you prefer?
moderate: high contrast or low contrast are not always diagnostic. Therefore, extreme contrast should be avoided.
194
Your doctor suspects a large cyst in the patient's mandible. A cyst is a diseased cavity in the bone. What adjustment can you make to your machine to provide an excellent diagnostic radiograph for your doctor? Your machine allows modification of kVp, mA, and pulse.
Decrease KvP and mA
bone with his cyst means less tissues. Therefore, lowering the kV, mA or the time of exposure provide us with a diagnostic radiograph.
195
Your patient has caries, periodontal bone loss, root fracture, and a periapical lesion. How would you process the image?
Increase the brightness.
Increasing the brightness will improve the image.
196
Your doctor placed several metal crowns. On a follow-up radiograph, she noticed defective margins of all the restorations. What may have happened?
over sharpening of the images. Excessive sharpening of the images will enhance the edges of restorations or metal objects.
197
A bitewing radiograph was taken to identify proximal caries. However, the caries may be small. What can you do to improve the diagnosis?
Increase the contrast
Increasing the contrast will show caries better.
198
A patient may have a root fracture. What can you do to the periapical radiograph to improve the diagnosis?
Increase the sharpnessIncreasing the sharpness will reveal the edges better.
199
VA of Maxillary Molar:
+ 30 degrees
200
Va of Maxillary incisor:
b. Maxillary incisor: + 30 degrees
201
Va of Mandibular molar:
+ 5 degrees
202
Va of Mandibular incisor:
minus 15 degrees
203
Which radiograph should fully record the first maxillary molar
Premolar Radiograph
204
Where should the central ray be pointed for a molar bitewing?
For molar bitewing, the central ray entry should be in the inter-proximal contact between first and 2nd maxillary molars.
205
List a few reasons that you should not use bisecting angle technique.
There are several reasons for not using bisecting angle technique. The primary reason is creating an imaginary geometry during the technique. In addition, in bisecting angle thinking, the images are often distorted, either elongated or foreshortened.
206
How can you best establish the patient in the proper focal trough? Select the best choice:
bite on the bite block
207
List a few common patient preparation steps for panoramic and cephalometric radiography.
1) Remove all jewelry, eyeglasses or any other metal object.
2) Ask the patient remained motionless.
3) Ask the patient to swallow and hold.
208
. For cephalometric radiography, which plane should be parallel to the floor?
Frankfort
209
When chromosomes mis-repair after radiation damage, the cells may undergo
profilteration
Following radiation, the damaged chromosomes may lead to cell death or cell proliferation. Cell proliferation is the main reason that causes cancer.
210
Any damage to the chromosome is lethal to the cells.
False:Not all chromosome damage is lethal to cells. Some damaged chromosomes will repair with or without errors.
211
Which toxin causes radiation damage to the cells
Hydrogen Peroxide
About 70% of our body is made up of water. Radiation can damage the water molecule, known as radiolysis. In this process, the water molecule converts to hydrogen peroxide which is a toxin. The hydrogen peroxide in turn will cause damage to the cellular structures.
212
The major way that radiation damages cellular structures is by modifying
Water Molecules
he major pathway for radiation induced cell damage is through water molecules. The water molecules will break and may form hydrogen peroxide
213
During radiation therapy, what is the preferred mode regarding normal cells?
Damage to one strand of DNA.
After radiation therapy, we want the normal cells to function normally. Therefore, if one strand of the DNA is damaged, the chromosome may be able to repair itself without error.
214
During radiation therapy, what is the desired action regarding cancer cells?
After radiation therapy, we do not want the cancer cells to repair itself. Therefore, we want both strands of the DNA should be damaged.
215
For an error-free repair of a damaged chromosome, what is essential?
Intact second strand
216
After radiation damage, what causes malignancy?
Repeat proliferation of cells may cause malignancy.
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What is the most critical part of a cell related to radiation damage?
DNA
218
Radiation-induced cancer of the jaws is clinically different than smoking-induced cancer.
FalseRadiation-induced cancers are not different from any other kind of cancers, either clinically or histopathologically.
219
fter radiation exposure, cancer caused by the radiation can appear
after several years cancer may appear after 10-30 years of radiation exposure.
220
Which of the following can be an example of the stochastic effect of radiation?
Salivary Gland Cancer after 12 years
Stochastic effect is something that may happen by chance. Redness of the skin and loss of hair after radiation therapy will always happen. These are deterministic effects. After a large dose of radiation (40 Gy) from an industrial accident, death is certain. However, cancer (and genetic mutation) may or may not happen after radiation. Therefore, cancer is a stochastic effect of radiation
221
Oral cancer is more likely to be seen in older adults. What types of cells are more sensitive to radiation?
we learned that youngers tissues and organs are more radiation sensitive. On page 17, we learned that oral mucosal cells are moderately sensitive to radiation while mature bone cells are least sensitive to radiation.
222
What types of cells are more sensitive to radiation?
we see that germ (sperm) cells are most sensitive. Oral mucosal cells are moderately sensitive. Cartilage cells and nerve cells are least sensitive.
223
What kind of effect is most likely to happen from a panoramic radiographic unit?
Deterministic effects take place from high dose of radiation. From dental radiographic machines, the effect anticipated is stochastic. This effect will include cancer.
224
The latent period in radiation biology usually means:
the occurrence of cancer after radiation
225
Why should we use rectangular collimation for intraoral radiography instead of round collimation?
The effective dose will be lower
The effective dose is to estimate the risk of radiation in human. The exposure is a measurement of radiation traveling in air. Equivalent dose is used to measure the biologic effects of different types of radiation. The radioactivity is a concept related to radioactive materials.
226
In TLD, how the radiation dose is measured? The dosimeter is
Heated to release light
In case of TLD, the crystals are heated to release visible light. The intensity of the visible light is measured for detecting the radiation received by the operator. This
227
Effective dose tells us
We described this concept with an analogy of gunshot wound to the body. A gunshot to the head has a much serious effect compared to a gunshot to the finger. Similar concept is about effective dose. It describes how different tissues response to radiation. This is described on page 10 of the handout.
228
Exposure is a measurement of radiation
exposure is a measurement of radiation in air, irrespective of the presence of any person.
229
Which tissue will have a higher absorbed dose? (Hint: think about radiographic density)
Compared to other tissues, bone will absorb more radiation.
230
What is the highest risk from dental radiography?
Types of Cancer
231
Why should you be careful in taking a panoramic on a 10-year-old?
The cells in a child are quickly dividing.
we learned that the risk of radiation is 2 to 3 times higher in children. This risk is due to increased cellular proliferation as we learned in unit 23 from Bergonie and Tribondeu’s axiom.
232
After radiation therapy, what conditions may recover back to normal?
of the conditions listed above, only oral mucositis may completely return to normal in a few months after radiation therapy.
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A single exposure is sufficient to cause cancer. More radiation increases the chance of getting cancer. Think of the Powerball example. A single ticket is enough to get he jackpot. Buying more thickets will increase you chance to getting the jackpot, but no guarantee.
234
What is the highest risk from radiation therapy for oral cancer?
steoradionecrosis is the most serious complication following radiation therapy.
235
If 5 million Americans receive panoramic radiographs, how many are likely to die from radiation-induced cancer?
he table on page 22 tells that if 1 million people are exposed to panoramic radiography, 0.21 people will die from radiation -induced cancer. This statistical analysis can be understood better if we multiply by 5. It means that if 5 million people receive panoramic radiographs, one person is likely to dies.
236
When mounting processed radiographs, the anatomical landmark that can assist you in mounting the molar bitewing is
The external Oblique
237
During panoramic positioning of the patient, if the patient’s chin is positioned too low, the following will be seen on the processed radiograph:
238
How will image receptors appear if they have been left in the fixer solution overnight?
Clearf image receptors are left in the fixer solution overnight, they will appear clear. This is due to how the fixer solution reacts with the emulsion on the image receptor. The fixer solution has the role of removing any non-energized emulsion crystals from the image receptor, so when an image receptor is left in this solution for an extended amount of time, all of the emulsion will be removed.
239
Chronic radiation exposure is being exposed to small amounts of radiation over a long period of time. This type of exposure has a long latent period; it is hard to link symptoms with a specific event because symptoms may not develop until 10 or 20 years after the chronic exposures.
Chronic radiation exposure is an unspecified amount of exposure over a long period of time. The amount of exposure and the overall length of time that the exposure was given will determine if it will cause a lasting effect.
240
The difference between acute radiation exposure and chronic radiation exposure is:
The difference between acute and chronic radiation exposure is the amount of radiation received and the time frame in which it is absorbed.
241
In acute radiation exposure:
a large or very high amount of radiation is exposed over a short period of time.
242
Identify the density and contrast of an image receptor produced using a high kilovolt or kV setting:
Increased density; low contrast.
243
Which of the following is a main disadvantage of using digital imaging in dentistry?
The sensor size and thickness.
244
The maximum permissible dose of radiation exposure allowed to a dental auxiliary in a 13-week consecutive period is:
The maximum permissible dose (MPD) of radiation, which is set by the National Council on Radiation Protection and Measurements, states that a dental auxiliary cannot receive more than 3 roentgens during a 13-week consecutive period
245
Bitewing should be a standard of (VA)
+10 Vertical Angle
246
What is the role of filtration in patient protection?
Reduce the number of low energy photons
The purpose of filtration is to remove long-wavelength x-ray photons with low energy and less penetrating power. Such long-wavelength radiations do not contribute to image formation but contribute to the radiation dose to the skin. Adding a filter, such as a sheet of metal will reduce the amount of low-energy radiation
247
What is your benefit from a lower radiation dose to the patient?
Lower occupational dose: The question is about your benefit. Since you are classified as an occupational radiation worker, any dose reduction to the patient will also automatically reduce the dose to us (occupational workers) and also other non-occupational workers.
248
Your coworker, a dental hygienist, broke his central incisor while working in the dental office. He has an order from the doctor for a periapical radiograph. For radiation safety purposes, how would the dental hygienist be classified for this periapical radiograph?
patient
249
A dental assistant was in a motor vehicle accident. In the last six months, he received several chest and head CTs and also several radiographs of his legs. He is fully recovered and returns to the dental office as a full-time employee. Please discuss when he will be safe to take panoramic radiographs on patients to avoid exceeding the maximum permissible dose.
he radiation that the dental assistant received for his motor vehicle accident could be classified as patient exposure. Therefore, these exposures are not counted towards his maximum permissible dose. There is no restriction on him to start taking panoramic radiographs on other patients. The concept is discussed on page 12 of the handout.
250
Briefly and in simple language, explain the concept of inverse square law for radiation safety.
Intensity, amount, or quantity of radiation is inversely, proportional to the square of the distance from the source
The inverse square law tells us that the farther we are from the radiation source, the safer we are. If we cannot step out of the room, we should be at least 6 feet away from the x-ray source.
251
What type of radiation is the most dangerous for the operator
The leakage radiation is most dangerous to the operator as it is not filtered. Also, the leakage radiation traverse in random directions. Therefore, a safe zone for the operator cannot be determined for leakage radiation.
252
Describe a few ways that you can avoid misuse of handheld x-ray machines.
Storing the handheld x-ray machine in a locked cabinet and removing the battery while not in use will reduce the possibility of accidental exposure. We should also stop using the x-ray machine if the safety ring is broken. The answer is available on page 10 of the handout.
253
According to NCRP, Who is a qualified expert for x-ray facility designing?
Health physicist
254
What is ALARA?
As Low As Reasonably Achievable
255
For the CBCT room, the walls should be lead-lined.
True: Lead-lined walls can provide adequate safety to the neighboring non-occupational public. However, it is not necessary to have lead-lined walls. Brick walls, concrete, or other materials may also be sufficient as barriers. The answer is on page 3 of the handout.
256
What is ‘workload’ for radiation safety
mA x minutes per week
257
Which of the following is most important for barrier designing?
The Presence of a Person:The barrier protects people on the other side of the x-ray room. If the other side of the room has no human activity, we do not have to worry about a barrier.
258
What is the Minnesota policy about registering x-ray equipment?
Registration must be done prior to operation: If changes are made to the x-ray room or the x-ray machine is sold, the Department of Health should be notified within 30 days. However, the machine must be registered before the first operation. The answer is on page 4 of the handout.
259
In Minnesota, operators cannot share a TLD badge for radiation monitoring?
False
260
Which of the following is a requirement in Minnesota for dental radiography?
Watching the Patient during radiology
261
Which of the following intraoral machines will not be allowed in Minnesota? Machines working at
45 kVp
262
Minnesota does not allow intraoral machines to operate under 50 kVp. How do the guidelines from NCRP differ on this issue?
NCRP guidelines state that machines shall not operate under 60 kVp
263
According to NCRP guidelines, what should be the minimum length of a PID?
20 cm
264
Higher the Ma the __________ Density
more
265
Lower the mA the _________ Density
less
266
Higher the kV _________ Density
more
267
Lower the kV _________ Density
less
268
Longer time of exposure _________ Density
more
269
Shorter time of exposure ____________ Density
ldss
270
An increase in any of the three exposure factors (kV,mA or time) will _____________ the density
increase
271
A drop in any of the three exposure factors (kV,mA or time) will _____________ the density
decrease
272
More thickness= ________ Density
less
273
Less Thick= ________ Density
more
274
What are different ways that you may enter patients ID
For patient ID, name, date of birth, address, phone number, chart number or even SS number can be used. The use of social security number in medical charting system has become rare. .
275
In Minnesota, who is allowed to order dental radiographs?
n Minnesota, the following people may order dental radiographic examinations: a) licensed dentists, b) licensed dental hygienists and licensed dental therapists who have collaborative agreement with the licensed dentist, c) and other individual specifically authorized in Minnesota statute.
276
Let's recall what we learned in unit 30 (Guidelines from NCRP). How should we preserve patient data?
In Unit 30, on page 3 of the handout, we learned that all digital images shall be retained in the patient's electronic record and should be backed up offsite electronically in a separate safe and secure location at regular intervals.
277
Your office has a CBCT unit. Other doctors from the town send patients to your office for CBCT images. A patient arrived at your office but forgot to bring the order. How can you manage this situation? The patient stated that the CBCT is needed for a maxillary anterior implant.
Decline the scanIn unit 29, MN Radiation Rules, page 15 of the handout, we learned that operator must have the radiographic order at the time of the examination.
278
You entered the following text in the chart. Please provide any missing information. Chart entry: May 26, 2002. One pan for Dr. J. No retake. Beth D. LDA.
For a good entry, we need to write the reason for the exam, full name or at least the full last name of the doctor, the date of order and your last name completely. Better entries would be as follows:
May 26, 2022. One pan for third molars, Dr. B. Johnson, ordered on 5/26/2002, No retakes. Beth Devine, LDA.
May 26, 2022. One panoramic, Bruce Johnson, DDS ordered on 5/26/2002 to see a radiopacity in the left maxilla, No retakes. Beth Devine, LDA.
279
How often should the radiation quality assurance program be reviewed in a dental office?
12 Months
280
Who appoints a radiation safety officer?
Dental Office Manager
281
List at least four responsibilities of a radiation safety officer.
1) safe use of radiation
2) managing radiation protection program in the dental office
3) identifying problems related to radiation protection
4) collecting and documenting radiation quality control tests
282
Who is responsible for creating a radiation safety manual?
The RSO, following MN statute
It is the responsibility of the radiation safety officer to establish a quality assurance program that will comply with the applicable requirements of Minnesota statute 4732.0505.
283
According to WHO, when can you use a hand rub?
When the hand is not visibly soiled.Chemical solutions should not be used with gloves. When the hand is visibly soiled, the hand should be washed. A hand rub is an option when the hand is not visibly soiled.
284
For infection control, which of the following radiography item is considered semi-critical?
A panoramic bite block will touch the mucosa of the lip. Therefore, this item is considered semi-critical for infection control
285
Which of the following is NOT a direct pathway of transmission of disease?
contact with saliva
contact with the patient's breath
contact with a contaminated countertop
contact with a tooth surface
Contact with the contaminated surface or instrument is considered an indirect pathway of disease transmission.
286
. How should you prepare a sensor holding device for infection control purposes
ensor holding devices come in contact with oral mucosa. Therefore, non-disposable sensor holding devices must be autoclaved.
287
In a few words, describe how cross-contamination can happen in a dental office.
Cross-contamination in a dental office happens when an infection spreads from a patient to a healthcare provider or from a healthcare provider to a patient.
288
Which of the following is considered a critical item in dental radiology for infection control purposes?
None of the dental radiology items penetrate soft tissues or bone. There is no item in dental radiology considered as a critical item for infection control purposes.
289
According to CDC, when should you put on the gloves while wearing PPE?
The final step of wearing the PPE is donning the gloves.
290
What are the three critical conditions for disease transmission
Host, bacteria or virus, entry path to hostemember that a disease may transmit from many sources, not necessarily from a patient or blood or saliva. We, as dental providers, should consider ourselves as a potential host of diseases. When we block the path of entry of bacteria or viruses by exercising infection control and wearing PPE, we can prevent disease transmission. The patient is also considered a potential host of diseases. We should take precautions so that the entry of diseases into the patient's body can be eliminated.
291
What is the ideal way of preparing a semi-critical item for infection control?
autoclaveThe ideal way of preparing a semi-critical item for infection control is sterilizing or autoclaving. The answer is on page 11 of the handout. In dental radiology, several items are semi-critical, e.g., sensors, PSP plates, or intraoral radiographic films that come in contact with the oral mucosa. However, sensors or plates will be destroyed if autoclaved. Hence these items are wrapped in barriers.
292
According to CDC, when should you take off the gloves while removing PPE?
loves should be removed at the beginning of removing the PPE.
293
How long should it take for a hand rub?
20-30 seconds
294
What is the name of the outer surface of the alveolar bone?
Cortex, the outer surface of the bone is called the cortex or cortical plate.
295
Which are the anterior teeth?
Incisors and canines only.
The anterior teeth include the central incisors, the lateral incisors, and the canines (cuspids). The bicuspids are the premolars. The premolars are part of the posterior teeth.
296
For an incisor, the surface closer to the lip is called
Labial
297
On a patient's chart, the mandibular right first molar is written as #30. Which tooth numbering system has been used?
Universal Numbering system
298
Which tooth will not be present in a deciduous dentition?
The deciduous dentition does not have premolars.
299
Increased density of the trabecular bone is called
Sclerosis
300
Increased density of trabecular bone is called sclerosis. Sclerosis can also happen with soft tissues.
301
Air Kerma
Kinetic Energy Released in Matter
302
Air Kerma Unit
(Gy)
303
Absorbed Dose Definition
Measures how much energy radiation deposited in a unit of material
304
Absorbed Unit Dose Traditional Unit and SI unit
Traditional: RAD, SI Unit: Gy
