Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Radiology > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

What is a bremsstrahulung X-ray?

A

A nucleus of an atom is bombarded with electrons. Usually tungsten.

This will account for the bulk of the X-ray photons produced.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What comprises the tube head?

A 
Metal housing 
Powersupply(transformers
X-ray tube 
Oil
Collimater 
Aluminum filters 
Aiming cylinder (lead lined)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe high energy, medium energy, and low energy regarding bremsstrahlung radiation

A

High energy - Electrons directly collide with a nucleus, producing a high energy photon that is equal in energy to the incident electron.
Medium energy - electrons pass really close to the nucleus causing a sharp turn in the direction on the incident electron. This sharp turn will release energy in the form of a photon.
Low energy - same concept as the medium energy except the electrons pass at a distance, causing a wider turn and less energy released

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe characteristic radiation.

A

An incident electron is projected at an atom. This electron strikes an electron in the inner shell and causes it to exit the atom. With a void in an inner shell, electrons fall back down to fill it up. In this process, energy is released.

It is important to note that the amount of energy is chracterisitc of the atom it involves. For example, tungsten is 59eV

This accounts for only a small amount of the X-ray photons generated.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the cathode and anode in an X-ray tube.

A

Cathode: - a tungsten filament and molybdenum focusing cup provide the source and direction of electrons of the cathode ray. Low voltage is used to heat the filament, producing a cloud of electrons through thermionic emission. The molybdenum focusing cup focuses the electrons into a narrow beam.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

True or false… light, heat, sound, and microwaves are all examples of radiation

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Define radiation. What is the difference between ionizing and nonionizing radiation?

A

Radiation is the transmission of energy through space and matter.

The difference between ionizing or non-ionizing radiation is its ability to knock out electrons, thus breaking bonds. Ionizing is able to do so and has a lot more energy. Ionizing radiation produces molecular chemical change and can lead to cell death and other harmful effects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

About what percent of radiation comes from natural sources?

A

50%

The other 50% is man mad sources

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the greatest source of natural radiation?

A

Radon (37% of total radiation exposure)

Cosmic 5%
Terrestrial 3%
Internal 5%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the greatest source of man made radiation?

A 
CT scans (24% of total radiation) 
Medical X-rays (12%)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the difference between particulate radiation and electromagnetic radiation? Name some examples of each

A

Particulate radiation typically associated with a lot more energy. Involves particles. (Alpha particles, beta particles, neutrons). Electromagnetic radiation involves photons (gamma rays, X rays)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q 
Which of the following is not a form of ionizing radiation? Why?  
X-rays
Microwaves
Gamma rays
UV light
A

Microwaves, because these have lower energy than visible light. The other types of radiation have more energy than visible light, thus are ionizing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is dosimetery?

A

How radiation is measured

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q 
What are the SI units for the following?  
Exposure
Absorbed dose
Equivalent dose
Effective dose
Radioactivity
A

Coulomb/kilogram

Gray (Gy)

Sievert (Sv)

Sievert. (Sv)

Becquerel (Bq).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What does the measurement of radioactivity measure?

A

Decay rate of a radioactive material.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does exposure measure?

A

Exposure is. A measure of radioactive kinetic. Energy emitted from a source and is quantified by its capacity to ionize air. It is a measure of the intensity of the radiation field. It is expressed in units of charge per mass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is absorbed dose?

A

The absorbed dose is the energy absorbed by any type of matter, and is derived by calculating the imparted energy divided by the mass absorbing it. Measured in Grays.

Some of the energy absorbed will make changes, some doesn’t affect anything. Absorbed dose simply measures how much is absorbed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is equivalent dose?

A

The equivalent dose is used to compare the biological effect on a tissue from different types of radiation.

Dependent on linear energy transfer, which varies depending on the type of radioactive therapy.

Particulate radiation has higher LET than photons, thus a greater biologic effect.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe linear energy transfer

A

Particulate radiation > photons.

think of particulate radiation like a large marble hitting a smaller one. Lots of potential energy is transferred. Photons, however is like sand hitting a marble, it doesn’t really do much

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is effective dose?

A

Effective dose is used to measure the estimated risk to humans

This takes into account the type of radiation (equivalent dose) and the nature of each organ or tissue being irradiated, then sums it up to get a whole body effective dose.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

List in order from most to least, the following tissue/organs by how susceptible they are to radiation damage.. brain, breast, skin, thyroid, gonads

A

Breast, gonads, thyroid, skin, brain

More rapidly dividing, less differentiated cells are most susceptible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

The reason we may wish to cover the reproductive organs of a patient when taking radiographs can be explained by the concept of ___

A

Effective dose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

In regards to radiobiology, what is the direct effect? What are some of its free radical fates?

A

When a photon or secondary electron ionizes biological macromolecules.

The free radical can then break down into two smaller molecules (dissociation), or it can undergo cross-linking meaning that it can join with other free radicals to form new molecules

Accounts for 1/3 of biologic damage from X-rays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Radiolysis of water occurs when a photon is absorbed by water in an organism, ionizing water molecules into free radicals. The products formed from this could be…

A

H* and OH*

In the presence of dissolved O2…

HO2*
H2O2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the indirect effect?

A

Free radicals and toxins produced through the intermediate step of water radiolysis interact with biologic macromolecules to cause changes.

involves radiolysis of water as a precursor to biologic damage. It accounts for 2/3 of biologic damage from X-rays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the primary cause of radiation induced cell death?

A

Damage to DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Damage to DNA results from… (4 things)

A

Breakage of one or both DNA strands

Cross-linking of DNA strands within helix to other DNA strands

Change or loss of base

Disruption of hydrogen bonds between DNA strands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

True or false… H2O2 contributes to the indirect effect of ionizing radiation on altering DNA?

A

False

Once H2O2 is produced, it doesn’t affect DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the deterministic effect?

A

Radiation injury dependent on the dose (the greater the dose the greater the severity)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What are some long-term effects of irradiation (months and years after exposure)

A

Loss of parenchyma cells and replacement with fibrous connective tissue

Loss of capillaries with impairment of oxygen transport, nutrient transfer, waste removal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What are some modifying factors of the deterministic effect on tissues?

A

Dose - above threshold level damage is proportional to dose (yes there is a threshold for deterministic effect)
Dose rate
Oxygen - damage increases as oxygen increases
LET

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Is radiation more or likely to affect cells that are highly differentiated or undifferentiated?

A

Undifferentiated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q 
What are the clinical manifestations of the following doses? 1-2 Gy
2-4 Gy
4-7Gy
7-15 Gy
50 Gy
A 
1-2: prodromal symptoms
2-4: mild hematopoietic symptoms
4-7: severe hematopoietic symptoms
7-15: gastrointestinal symptoms
50: cardiovascular and CNS symptoms
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is the stochastic effect?

A

Radiation injury is based on the probability of occurrence (All or none phenomenon). The probability of the effect occurring increases with dose. there is NO threshold level.

The occurrence of radiation induced cancer and genetic alterations are stochastic effects, resulting from sublethal damage to dna

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What are the three guiding principles to radiation safety?

A

Justification
ALARA
Dose limitation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What does ALARA stand for?

A

We should keep radiation exposures As low as reasonably achievable for adequate diagnosis and evaluation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What justification mean in regards to radiation safety?

A

The dentist has the obligation to do more good than harm. In selecting radiographs, the benefit to the patient from diagnostic exposure should exceed the low risk of harm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

True or false… there are set dose limitations in diagnostic and therapeutic radiology

A

False. However the dentist should limit the amount of exposure as much a as possible by adhering to good radiation safety practices and have a radiation protection program in place.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

True or false.. dentists should not prescribe routine dental radiograps at preset intervals for all patients

A

True. Rather, they should prescribe radiographs after an evaluation of the patients needs that includes… a health history review, a clinical dental history assessment, a clinical examination, and an evaluation of susceptibility to dental diseases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

True or false.. we can take radiographs on pregnant patients at our university if given maximum protection

A

True. Just no routine radiographs

41
Q

What type of film should you use when taking radiographs?

A

Use high speed film that requires less radiation exposure. Use E or F speed film instead of D

42
Q

True or false.. digital imaging requires less radiation exposure than speed film

A

True

43
Q

True or false… intensifying screens make radiographs more effective and require less exposure

A

True

44
Q

Rectangular collimeters reduce the area of exposure by ____ when compared to circular collimeters

A

60%

45
Q

A thin ____ filter is typically used in the tube head to filter dental X-rays. What does this accomplish?

A

Aluminum

Removes lower energy, easily absorbed photons so that they do not get to the patient. This allows only the necessary and effective high energy X-rays to get to the patient to make it all the way to the film

46
Q

How far should you stand from the radiation source when taking a radiograph?

A

2 meters (6 feet)

Remember that radiation exposure decreases inversely to square of the distance

47
Q

The operator should be ____ degrees from the primary X-ray beam

A

90-135

48
Q

True or false.. it is acceptable to have the patient or parent hold the sensor in the patient’s mouth if necessary

A

True. But you, the dentist/assistant, should not

49
Q

The UT division of radiation control inspects dental X-ray units and their use environment every ___ years

A

5

50
Q

Describe how an X-ray tube works. Describe vacuum tube, target, and focal spot

A

Vacuum tube: no gas molecules for electrons to collide with, no burnout of filament.
Target: has to have a high atomic number, high melting point, high thermal conductivity and low vapor pressure. Tungsten.
Focal spot: this is the point on the target where the stream of X-ray originates. Its small as possible for best radiographs but large enough to dissipate heat, target is at an angle.

51
Q

A molybdenum focusing cup in an X-ray tube does what two things? Where is it located?

A

Narrow the beams of electrons

Directs electrons toward the tungsten target

Is located in the cathode

52
Q

Describe the power supply of an X-ray tube

A

Low voltage tube current heats the tube filament, generating a stream of electrons between the cathode and anode. (A step down filament transformer is used to bring the voltage down from 110v to 3-5 volts)

High voltage between the cathod and anode accelerates electron stream to a level that X-rays can be produced (a step up transformer is used to bring voltage from 110v to 60-100kv.

53
Q

What is the most frequent source of malfunction in the X-ray tube? How do you avoid this?

A

Filament burnout

This is avoided by keeping the X-ray machine ON all day. Turning it on and off in between patients puts strain on the filament and will cause it to burnout

54
Q

True or false… increasing the power to the low voltage tube current will increase the energy of the emitted X-ray beam.

A

False… an increase in power of the HIGH voltage step up transformer will accomplish this

55
Q

True or false… doubling the time will double the exposure

A

True

56
Q

What happens when you increase the tube current (mA)?

A

More electrons are released to collide with the target. More collisions = more radiation

*increase in number of electrons

57
Q

What happens when you increase the tube voltage? (KVp)

A

Increasing the potential between the anode and cathode increases the energy of each electron when it strikes the target.

This increases the efficiency of the conversion of electron energy into X-ray photons.

*ultimately this increases the X-ray penetration in the matter

58
Q

What is a collimator?

A

A metal barrier used to reduce the size of the xRay beam. Used to absorb stray photons and reduce scatter. Rectangular are more safe but more difficult to use than circular collimators

59
Q

According to the inverse square law, if you are standing four feet away from the source of radiation, how much of it is getting to you?

A

1/16th

4 squared = 16… inverse = 1/16

60
Q

What is photoelectric absorption?

A

This is the process in which incident photons are absorbed by an atom by interactin with inner shell electrons. This is what makes the lighter areas on the film. P.A depends on the density and thickness of an object, thus creating contrast between different tissues in a film

61
Q

Will a totally unexposed film be white or black?

A

White

62
Q

What is coherent scattering?

A

Coherent scattering occurs when low energy photons are deflected by outer ring electrons. No actual collision takes place

Accounts for about 7% of interactions, so it contributes little to film fog

63
Q

What is compton scattering?

A

This occurs when a photon interacts and collides with an outer orbital electron.

This contributes to ~49% of film fog

64
Q

Describe beam attenuation

A

Lower energy photons are more readily absorbed as they travel through matter. As the energy of the photon beam increases, so does the transmission of the beam through the absorber

65
Q

True or false… when an X-ray machine is turned off, there is no residual radioactivity

A

True

66
Q

True or false… lead aprons are required when taking radiographs

A

False. But they should be given to pregnant women and children

67
Q

On a dental chart, what does.it mean if there is a black, blue, or red X on a tooth?

A

Black = congenitally missing

Blue = previously extracted

Red = needs to be extracted

68
Q 
What does it look like to chart the following... 
composite resin
Amalgam
Gold
Porcelain/ceramic crown
A

Composite resin = outline surface in blue

Amalgam = fill in surfaces in blue

Gold = cross hatch surfaces in blue

Porcelain/ceramic crown = outline entire tooth in blue

69
Q

What does an ‘S’ mean on an odontogram?

A

Sealants

70
Q

What are three ways to maximize sharpness and resolution?

A

1) use a small and effective focal spot
2) increase distance from source of focal spot to object
3) minimize distance from object to image receptor

71
Q

The sharper the angle of the target, the more ____ the focal spot. Thus the focal spot will be more in focus.

A

Narrow

72
Q

Increasing distance from the source or X-rays to the object will increase the clarity of the image. However, if you move it too far, what may happen?

A

If you move it too far back, the X-rays will not have enough energy to penetrate far enough to reach the film

73
Q

True or false… keeping the film (image receptor) close to the tooth you are trying to image will make the image more clear

A

True

74
Q

Image size distortion can be minimized by what two things?

A

Increase focal spot to image receptor distance

Decrease object to image receptor distance.

(Think about shadows and a flashlight)

75
Q

Image shape distortion can be minimized by doing what two things?

What are the two different types of shape distortion?

A

Position the image receptor (film) parallel to the long axis of the object (tooth)

Orient central ray (cone) perpendicular to the object and image receptor

Foreshortening and elongation

76
Q

What causes foreshortening?

What causes elongation?

A

foreshortening: When the film is not parallel to the object but the beam is perpendicular to the film. (Beam and film are perpendicular but the object is not)
elongation: the beam is perpendicular to the object but the film is not.

77
Q

Describe the paralleling technique

A

Central ray should be perpendicular to the long axes of both the tooth and the image receptor. This produces the least amount of distortion and is the preferred method.

78
Q

What is the bisecting-angle technique?

A

The central beam should be directed perpendicularly to an imaginary bisecting line. This imaginary bisecting line is mid way between the long axis of the tooth and the film.

This technique is used to fit the whole tooth onto the film, while minimizing the amount of size distortions in the tooth

79
Q

What is the SLOB rule? How does it work?

A

Same Lingual, Opposite Buccal

This is used to determine if an object is located buccal or lingual to a reference object.

After taking the first radiograph, take another to determine the location of the object in relation to the reference object. Take an image from a mesial view, then compare the two images. If the object appears to have moved mesially (same direction you moved the cone) compared to the reference image, the object is lingual to the reference image. If it appeared to have moved distally, it is buccal to the reference object.

80
Q

How can you increase periapical coverage by moving the tube head?

A

Angle the tube head 5-15 degrees more towards the crown than the instrumentation indicates.

Note that it will actually cause foreshortening, that is why it increases periapical coverage

81
Q

How can you still image a tooth if the patient has low palates?

A

Place two cotton rolls over the biteblock (one on top, one underneath)

82
Q

At our school, How many films are used for a full mouth series? How many of each type?

A

18 films total. 14 PAs, 4 bitewings.

Use #2 film/sensor for all radiographs

83
Q

What should be included when taking radiographs of maxillary central incisors? Where should the central X-ray entry point?

A

You want to the the mesial contacts of each lateral incisor.

Tip of the nose

84
Q

What should be included in a maxillary canine PA? Where should you position the X-ray beam?

A

You want to see the distal contact of the lateral and mesial of first premolar.

Ala (corner) of the nose

85
Q

What should a maxillary bicuspid PA look like? Where should you place the X-ray beam?

A

Tip the film horizontally. You should at least include the distal contact of the canine

Point down from the pupil of the eye to mid-cheek area

86
Q

What should a maxillary molar PA look like? Where should you point the cone?

A

Should at least include the distal contact of the second premolar and third molar

Point down from the outer canthus (corner) of the eye to mid-cheek area

87
Q

Where should you position the cone when taking a mandibular molar PA?

A

Point down from the outer canthus of the eye to the mid-mandible area

88
Q

Where should you point the cone in a mandibular bicuspid PA?

A

Point down from the pupil of the eye to mid-mandible area

89
Q

Where should you position the cone when taking a mandibular canine PA?

A

Point down from the ala of the nose to the chin corner

90
Q

True or false… in a mandibular central PA, you should try and get all of the distal contacts of the laterals in view

A

False. You should get all of the mesial contacts of the laterals in view

91
Q

Where should you position the cone when taking a mandibular central PA?

A

Point down from the tip of the nose to the center of the chin.

92
Q

Both the adjectives radiolucent and radiopaque refer to the ____ not the ____

A

Object

Image

93
Q

Which is more radiopaque, cortical bone or calculus?

A

Cortical bone

94
Q

True or false… there is high contrast between cementum and dentin

A

False.. there is low contrast between cementum and dentin

95
Q

What is lamina dura?

A

Bone that is continuous with cortical bone at the alveolar crest.

Appears more radiopaque than other bone because the X-ray beam passes it at a tangent causing it to appear more dense, when in reality it is not any more mineralized than the surrounding bone.

Wider in teeth with heavy occlusion

96
Q

Normally, the alveolar crest should not be any more than ____ apical to the CEJ

A

1.5mm

97
Q

What does the PDL look like in a radiograph?

A

It is radiolucent

Seen between the root and the lamina dura

Wider near alveolar crest and root apex

98
Q

True or false… composition resins and porcelain is radiolucent

A

True

Radiology (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions