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BOARDs > Oral Radiology > Flashcards

Oral Radiology Flashcards

1
Q

Position-Indicating Device

A

Line up tube head

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2
Q

What is an X-ray?

A

High energy and High Frequency Wave
* between UV rays and Gamma rays

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3
Q

Attenuation

A

How the X-ray beam weaknes as it passes through matter on its way to receptor

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4
Q

Filtration

A

Involves aluminum

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5
Q

Collimation

A

Involves Lead
* Rectangular=best method to decrease pt exposure

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6
Q

What are the 2 types of Ionizing Radiation?

A

Electromagnetic

Particulate

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7
Q

Electromagnetic Ionizing Radiation

A

Energy Movement= Electrical Fiel + Magnetic Field

Shorter Wavelength= Increased Energy

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8
Q

Particulate Ionizing Radiation

A

Atomic nuclei or subatomic particles moving at high velocity

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9
Q

What are the 2 types of X-ray Production?

A

Bremsstrahlung

Characteristic

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10
Q

X-ray Production: Bremsstrahlung

A

Primary Source of X-ray Photons
* generates a continuous spectrum of energy

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11
Q

X-ray Production: Characteristic

A

Secondary Source of X-ray Photons
* emits a photon of specific energy when it moves orbitals

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12
Q

Intensity

A

Quantity of electrons & photons

Effects: Density
* Darkness of the image

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13
Q

Energy

A

Quality of electrons and Energy of photos

Effects: Contract
* difference among Gray values

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14
Q

Exposure Time

A

Changes the NUMBER of photons
* most frequently altered setting

Affects: Intensity (Density)

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15
Q

What if the exposure time is too long?

A

To Dark, overexposed

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16
Q

What if the exposure time is too short?

A

Noisy and light, underexposed

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17
Q

Tube Current (mA)

A

Not adjusted easily

Affects: Intensity (Density)

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18
Q

What if the tube current is too much?

A

Too dark, underexposed

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19
Q

What if the tube current is too little?

A

Noisy, underexposed

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20
Q

Tube Potential

A

Acceleratioin of e- from cathode to anode
* affects the number and energy of photons

Affects: Density & intensity

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21
Q

What if the Tube Potential is too high?

A

Too gray (not enough contrast)
mostly compton scattering

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22
Q

What if tube potential is too low?

A

Too light (Very high contrast)
mostly photoelectric absorption

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23
Q

Distance: Inverse Square Law

A

Inverse Square Law: Further from the source, Decrease photons per unit area

Intensity =1/distance
* short distance=Increase intensity=Increase Density=Dark

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24
Q

Ideal Distance

A

Incrase Source Object= Decrease Intensity (Density), Increase Quality
Decrease Object-Image Distance=Increase Quality, Decrease Magnification

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25
Q

Size depends on:

A

Focal Spot Szie
Source-to-Object Distance
Object to image distance

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26
Q

Ideal Size:

A

Decrease Focal Spot Size
Decrease Object to image distance
Increase Source-to-Object distance

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27
Q

Coherent Scattering

A

Incident Photon contacts outer electron

Effect: Decrease contrast

28
Q

Photoelectric Absorption

A

Incident Photon contacts & ejects an inner electron
forms an ion pair

Effect: Increase Contrast

29
Q

What happens to photoelectric absorption when kVp is too low?

A

Increase Photoelectric absorption

30
Q

Compton Scattering

A

Incident Photon contacts an outer electron
Form ion pair

Effect: Decrease Contrast

31
Q

Deterministic Effects:

A

Hair loss, Cataracts, Skin Damage, Oral Mucositis

Threshold needs to be reached:
* Less than=no effects

32
Q

Stochastic Effects

A

Cancer, Leukemia, Hertiable Effects

No threshold: Dose builds up over years

33
Q

Direct Radiation

A

Direct alteration of biologic molecules

34
Q

Indirect Radiation

A

Ionizing radiation converts H2O into free radicals
* alter biologic molecules

Cells that are mitoticallys active are more radiosensitive
* Most Sensitive: Hematopoietic cells, epithelial cells, sperm cells
* Least sensitive: Nerve cells, Muscles Cells

35
Q

Film vs Digital Imaging: General

A

Film:
* Requires chemicals to process
* quires time to develop
* Superior image quality
* More radiation dose to patient

Digital:
* No chemicals
* Instant viewing
* Image

36
Q

Film composition

A

Base: Flexible Plastic

Emulsion: Silver halide crystals in gelatiin material

Intensifying Screens:
* coated w/fluorescent phosphor
* Decrease amount of exposure needed
* decrease resolution

37
Q

Film Speed

A

A<B< C < D < E < F

38
Q

Film Speed is determined by:

A

Large Crystals: Faster films
Double Emulsion: Faster Film
Radiosensitive Dyes in emulsion=faster film

39
Q

Film Imaging: Chemical Processing steps:

A
  1. Developing
  2. Fixing: wash away unexposed silver halide crystals
  3. Washing: Wash away residual chemics
  4. Drying
40
Q

Chemical Procesing: Developing

A

Converts exposed crystals into metallic silver grains

If final image is light: Developer is porbably old

41
Q

Chemical Processing: Fixing

A

Wash away unexposed silver halide crystals
* Ammonium Thiosulphate: removes undeveloped silver halide crystals
* Aluminum slats: preserves emulsion

42
Q

Detector: Contrast resolution

A

Distinguish shades of gray

Film>Digital

43
Q

Spatial Resolution

A

Distinguish 2 close points

Film> CCD/CMOS> PSP

44
Q

Detector Latitude

A

Exposure range
* provide useful image

PSP> CCD/CMOS> FIlm

45
Q

Detector Sensitivity

A

Dose required to achieve standard gray level

CCD/CMOS is 1/2 the speed of F speed film=way less radation

46
Q

What could cause an image to be underexposed?

A

Inadequate exposure time
inadequate development time
old development solution
Temp too low

47
Q

What could cause an overexposed image?

A

Exposed too long
Exposed to light

48
Q

What are the types of intraoral x-rays?

A

Periapical
Bitewing
Occlusal

49
Q

What are the different type of extraoral x-ray?

A

Pan
Cephaolmetric
CBCT

50
Q

Occlusal

A

Receptor flat on occlusal plane
* canine to canine

assesses: Trauma, Impacted teeth, SUpernumery

51
Q

Panoramic

A

Used for:
screening
pathology
3rd molar location

52
Q

CBCT

A

Cone Bean Computed Tomography

3d image:
* axial view (top bottom)
* Sagittal (Side-side view)
* Coronal (Front back)
* 3D volumetric render

53
Q

CBCT is useful for

A

Implant planning
CBCT (Strange anatomy)
Ortho
TMJ
Pahtology

54
Q

Waters View

A

PA ceph at 45 degrees to obrito medial line

Best for:
* Paranasal sinus
* Midface
* Orbits

55
Q

Townes View

A

PA ceph at 30 degree from orbito medial line

Best for: Condyle
* eliminates superimposition of amstoid and zygoma

56
Q

Submentovertex View

A

Base projection of the skull

Best for:
* basilar skull fractures
* Zygomatic fractures

57
Q

Bisecting Angle Technique

A

Central ray of x-ray is aime perpendicular to bisecting line b/w:
long axis of the tooth
long axis of receptor

58
Q

Paralleling Technique

A

Receptor parallel to long axis of tooth
* Beam center perpendicular to long axis of tooth and receptor

Less distortion
Increase Image quality

59
Q

Elongation

A

Most common error

could be:
* angulation issue
* bending film

60
Q

Cone cut

A

X-ray beam & receptor not line up

61
Q

Underexposed

A

Grainy or too light
* too short exposure time
* Decrease mA and kVP

62
Q

Overexposed

A

image to dark
* Increase mA
* Increase kVp

63
Q

Double exposure

A

2 images exposed on same plate

64
Q

Pan: Motion Error

A

Wavy & irregular borders
* pt swallows or moves

65
Q

Corticated Unilocular

A

One Compartment
Radiopaque Border

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