Radiology I Flashcards Preview

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Flashcards in Radiology I Deck (165):
1

Radiation is the transmission of energy through space and matter and occurs in what 2 forms?

Particulate

Electromagnetic

2

Radioactivity releases alpha or beta particles or gamma rays generated where?

Inside the nucleus

3

Oral and maxilofacial radiology involves only what type of radiation?

Electromagnetic

4

What type of radiation in the electromagnetic spectrum is capable of ionizing matter?

High energy (UV and up)

5

T/F
Electromagnetic radiation is generated when the velocity of an electrically charged particle is altered

True

6

The energy of dental x-rays is 60k to 90 k.... (unit?)

eV

7

The x-ray tube is surrounded by insulating material, usually what?

oil

8

The X-ray tube has electrons stream from the ______ to target the ______.

Cathode

Anode

*energy from some e- is converted into x-rays

9

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.

Tungsten

Molybdenum

10

The Anode is a ______ target embedded in copper

Tungsten

11

The sharpness of an x-ray image ________ as the size of the focal spot Decreases.

Increases

12

What type of Radiation primarily emanates from an x-ray tube?

Bremsstrahlung Radiation

*German for "braking radiation"

13

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?

70 kVp

*so, fluctuated up to 70

14

The exposure time of an x-ray takes how long?

*time is directly proportional to photon exposure

fractions of second

15

The number of photos that reach the patient and image receptor is directly proportional to what 2 things?

current (mA)

time (s)

16

Beam quantity/intensity refers to what?

Number of photons in x-ray beam

17

What factor is related to the Tube Voltage Peak (kVp)?

Quality (meaning energy of x-ray beam)

18

Increasing the kVp of an x-ray increases what 3 things?

# photons

mean energy of those photons

maximal energy of photons

19

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

True

20

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?

Aluminum

21

T/F
The Collimator is a metallic barrier used to restrict x-ray size and is Round or Rectangular

True

22

The Collimator improves the image quality by decreasing what?

Scattered Radiation produced by absorbed photons

23

Describe the Inverse Square Law that applies to x-ray beams.

Double distance, intensity of beam is now 1/4

24

X-rays have an Incident Beam, Attenuation, and Scatter - what are the 3 types of Attenuation?

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

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