Radiology II Flashcards

1
Q

What is the most popular imaging modality in the US?

A

Film

*this is on the verge of changing

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2
Q

If the pt is bumped during imaging, what results?

A

Big wave - motion artifact

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3
Q

What is one difference between Cone Beam CT (CBCT) and pano?

A

CBCT has NO magnification

Pano has magnification

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4
Q

What has more radiation dose, Panoramic or FMX?

*how much is the dose?

A

FMX

175 microsievers

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5
Q

FMX with Round Collimation and Film has 175 microsievers.

How much with Rectangular Collimation and Digital or F speed film?

A

1/5 the Radiation

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6
Q

What are the advantages to a Pano? (3)

What is the drawback?

A

one shot overview, less radiation, easy to take

less detail

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7
Q

Pano’s are fast and convenient but won’t show what?

A

Interproximal caries

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8
Q

PSP is how many steps?

Digital is how many steps?

A

2 step process

1

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9
Q

PSP goes into processing machine that uses what?

A

Laser beam

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10
Q

In Direct Digital imaging (the CMOS or CCD sensors), what fluoresces when exposed to x-rays and forms visible light radiographic image?

*this is on the active side of the sensor

A

Scintillator screen

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11
Q

What is on the active side of a metal oxide semi-conductor sensor?

A

Scintillator

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12
Q

What couples the scintillator screen (fluorescing) to the CMOS chip to reduce image noise?

A

Fiberoptic face plate

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13
Q

What is a Matrix of Individual Blocks?

What technology uses this?

A

Voxels (volume elements)

CT (computed tomographic scanning)

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14
Q

Voxels (volume elements) are made up of square images of matrix called ______

A

pixels

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15
Q

In either CBCT or a Pano, you need to put the pt where?

A

In the Focal Layer

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16
Q

What is the universal way to store/transfer images in medicine?

A

Dicomm

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17
Q

A Pano is made with what shape of beam?

A

Vertical, narrow beam

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18
Q

A Pano rotates around what?

A

Focal plane/Focal trough

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19
Q

Describe the center of Rotation in a Pano:

A

moves continuously as tube/receptor rotate around pt

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20
Q

T/F
The closer an anatomic structure is positioned to the center of the trough, the more clearly it is imaged on resulting radiograph

A

True

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21
Q

Film, PSP, Digital Receptors - which are similar?

A

Film and PSP similar

Digital receptor black box solid state

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22
Q

If the mandible is positioned Anterior of the bite block, what happens to the image?

If Posterior?

A

Minification

Magnification

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23
Q

Rotate a pts head toward the Right, which side is minified, which is magnified?

A

Right side minified *rotated further away

Left side magnified

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24
Q

Excessive downward chin tip will produce what in a Pano?

Excessive upward chin tip will produce what in a Pano?

A

Too much “smile”

Frown

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25
Q

If a pts head is rotated in a Pano, which side is Minified?

A

Side in direction of rotation

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26
Q

What are the 6 standard Maxillofacial Projections?

A

Posteroanterior (PA)

Lateral Skull

Occipitomental (Waters)

Reverse - Towne

Submentovertex

Lateral Oblique

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27
Q

Name 3 structures for which the Occipitomental (Waters) Projection is indicated?

A

Sinuses

Nasal cavity

Coronoid process

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28
Q

Occipotomental (Waters) Projection elevates the canthomeatal line ____ degrees

A

37

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29
Q

What projection is indicated for condylar neck and posterior wall of the maxillary sinus?

(also get in submentovertex)

A

Reverse-Towne projection

*head down, open jaw

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30
Q

What projection travels is taken vertically through the head?

A

Submentovertex projection

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31
Q

What projection is good for abnormal premolar/molar region and inferior border of the mandible?

A

Lateral Oblique (body projection)

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32
Q

What projection is good for abnormalities of the ramus/condyle region and 3rd molars?

A

Lateral Oblique (ramus projection)

33
Q

What projection is good for the Mandibular Ramus?

A

Mandibular Oblique projection

34
Q

Describe Submentovertex view:

Describe Waters view:

A

travels vertically

head up (NWA look)

35
Q

Pano comes up at 12 degrees - this angle aka…

This causes horizontal structures to be displayed how?

A

parallax

vertically

36
Q

A ghost image is more ____ than its real counterpart

A

blurred

37
Q

What area in a Pano produces a particular angulated ghost image to the contralateral side?

A

Mandibular Ramus

38
Q

What 2 forms of imaging have zero radiation?

A

MRI and Ultrasound

39
Q

Basic guidelines for imaging children, radiographs 1st visit, Posterior bitewing intervals if Caries present?

If caries not present?

Adult caries present?

Adult caries not present?

A

6-12 months

12-24 months

6-18 months

24-36 months

40
Q

CBCT software takes data and undergoes primary or 3D reconstruction once base images have been acquires. Goes through what process -

multi-planar reformation, 3D reconstruction, or primary reconstruction?

A

Multi-planar reformation???

41
Q

When we’re talking about Cone Beam CT images vs other (medical) CT images

isotropic, mesotropic, magnification principles???

A

Isotropic means voxel same on each side

42
Q

T/F

Sometimes better resolution film is inferior to high res digital b/c of noise

A

True

*digital can be better diagnostically

43
Q

CCD and CMOS are ____ detectors

*can be wired or wireless

A

solid state

*these have the scintillator coating that fluoresces

44
Q

CCD and CMOS are ____ detectors

*can be wired or wireless

A

solid state

*these have the scintillator coating that fluoresces

45
Q

PSP makes a latent image that is scanned with what?

A

Laser

46
Q

T/F

We see better in dim light so if you shift toward darker spectrum we see images better

A

True

47
Q

_____ encoding takes advantage of the non-linear manner in which we perceive light and color.

A

Gamma

*we are more sensitive to relative differences of darker tones

48
Q

Relative importance of resolution, contrast and density to detecting dentoalveolar disease.

A

Resolution - not really important

Contrast and Density - much larger role

49
Q

What type of receptor opposite the vertical collimator of a Pano machine continuously reads exposure?

A

CCD - charge-coupled device

50
Q

Appears higher up than real image, more blurred, larger vertical component.

A

Ghost images

51
Q

Three types of images produced in Pano:

A

Real

Double

ghost

52
Q

T/F

The oral airspace artifact washes out the apical surfaces of the maxillary teeth

A

True

53
Q

What creates the most artifacts?

A

Motion

54
Q

What is standard FOV for maxillofacial imaging?

A

6” close up

55
Q

Effects where the risk is proportional to the dose:

Effects where the severity is proportional to the dose:

A

Stochastic

Deterministic

56
Q

CBCT is equal to ___ days of background radiation

FMX F-speed, rectangular collimation:

FMX D-speed, round collimation:

A

10

4.3

47

57
Q

FMX D speed round collimation to PSP rectangular collimation decreases radiation ___%

CBCT is around ___ times less radiation than D speed FMX

A

90

5

58
Q

MDCT (medical) is ___ times CBCT dose

A

30

59
Q

___% of calcium needs to be resorbed before seeing anything on a radiograph

A

10%

60
Q

T/F
Dynamic Periapical allows scrolling through different views

*all kinds of indications, type of CBCT

A

True

61
Q

CBCT stands for:

A

Cone Beam Computed Tomography

62
Q

In CBCT software can reorient the data, optimize, view and format

A

True

63
Q

All sides of Voxels are equal, meaning they are…

A

Isotropic

64
Q

What CBCT software analysis is best to examine alveolar bone?

A

MPR - multiplanar reformation

*due to isotropic nature of voxels

65
Q

An image slab in MPR (multiplanar reformation) is called…

Can slab be widened?

A

Ray Sum

Yes - to the point of full thickness

66
Q

T/F

A selective display of voxels in the data set will result in a Volume Rendering

A

True

67
Q

Max Intensity Projections (MIP) evaluates each voxel at its highest value as a type of ____ rendering

A

Direct Volume

68
Q

Operator of a CBCT must provide a ______ of the entire image data set

A

written interpretive report

69
Q

Jawline fracture sometimes won’t show up on what?

A

Pano

*CBCT will catch

70
Q

3 orthogonal planes (high res FOV CBCT scan):

A

Axial (horizontal)

Coronal (fronal)

Saggital

71
Q

Pixel assigned a number representing specific tissue density called a:

A

Hounsfield Unit (HU)

72
Q

There is higher tissue contrast in MDCT b/c more radiation and scatter of CBCT

A

True

73
Q

IV Contrast Imaging is based on ____

A

iodine

74
Q

3 artifacts of CBCT:

A

Partial volume (differing densities will blur image)

Beam hardening (the more tissue goes through)

Metal streaking (metal absorbs x-ray completely)

75
Q

Only place we use MRI in dentistry:

A

TMJ imaging

76
Q

Nuclear medicine uses ___ rays

A

Gamma

77
Q

Anterior mandible radiopaque artifact:

A

Lead apron

78
Q

Images with Parralax aren’t ideal for implants

A

True

79
Q

Vertical components of a ghost image are always larger and more blurred

A

True