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ORAL RADIOLOGY EXAM 2 > study this > Flashcards

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1
Q

2 examples of inherent filtration

A

glass envelope
tube window
metal housing
immersion oil

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1
Q

what occurs when you have a low kV

A

high gray scale

(high kV/voltage= low contrast= more shades of gray)
(low kV/voltage= high contrast= less shades of gray

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2
Q

inverse square law, if distances is doubled from 8 to 16, what is the new intensity

A

1/4

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3
Q

by using adjustment tools such as edge enhancer, you can stimulate illnesses and abnormalities to show that are actually not there

A

yes

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4
Q

too much info on computer can cause

A

not function properly

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5
Q

which of the following has most biological affect
direct or indirect

A

indirect 2/3
direct 1/3

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6
Q

XR photons absorbed by H2O-> free radicals-> biological damage

A

indirect

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7
Q

outcomes: repair, mutation, death
directly ionizes biological macromolecules

A

direct

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8
Q
  1. lethal dna damage
  2. cell death
  3. ex: xerostomia, acute radiation syndrome, erythema, fetal development
    HAS threshold
    severity is proportional to dose
A

deterministic (dose based)

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9
Q
  1. sublethal dna damage
  2. gene mutation
  3. replication of mutated cells
  4. examples: leukemia, thryoid cancer
  5. NO threshold
  6. severity of effects DOES NOT depend on dose
A

stochastic (frequency)

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10
Q

genetic mutations cause malignancy to what cells

A

somatic cells

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11
Q

genetic mutations cause heritable effects to what cells

A

germ cells

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12
Q

what factors modify effects of xradiation

A
  1. decrease age (pediatric pts at risk)
  2. increase dose rate
  3. increase total dose
  4. increase oxygen
  5. cell type and function
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13
Q

what stage of acute radiation syndrome is non lethal

A

prodromal period
<2 Gy

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14
Q

what is the most lethal stage of acute radiation syndrome

A

CNS/CVS
>100 Gy

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15
Q

what stage of acute radiation syndrome is lethal 2-8Gy?

what is supralethal >8Gy?

A

lethal: hemiatopietic
supralethal: Gastrointestinal

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16
Q

what is the effect of radiation on
mucosa
teeth
salivary gland
bone
muscle

A

mucosa: mucositis, 2 degree infection
teeth: radiation caries and underdeveloped teeth
salivary gland: xerostomia
bone: osteoradionecrosis
muscle: fibrosis

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17
Q

what kind of radiation causes radiation caries

A

indirect

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18
Q

what are
occupational limits
non-occupation limits
pregnant limits

A

occupational limits: 5 rem or 50mSv
non-occupation limits: 0.5 rem or 5mSv
pregnant limits: 0.5 rem or 5 mSv (9 months)
.1rem or 1mSv (1 month)

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19
Q

what kind of xrays do you take on pregnant patients

A

only take xrays during emergency circumstances

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20
Q

examples of background radiation

A

radon
cosmic
terrestrial
internal

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21
Q

what cancers have the highest risk for dental radiograph exposure

A

thryoid and leukemia

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22
Q

where should you stand when taking xrays

A

6 feet away, behind barrier, 90-135 degree from beam

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23
Q

primary reason for taking water’s skull xr

A

see the maxillary sinus

(chin is up)

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24
Q

SLOB rule, move tube mesial and object also moves mesial

A

lingual

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25
Q

what comprises the inverted Y

A

nasal cavity floor and maxillary sinus

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26
Q

which of the following provides the best protection against radiation

A

thyroid collar

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27
Q

when tooth is not parallel to receptor, and beam is directed perpendicular to receptor

A

foreshortening

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28
Q

when tooth is not parallel to receptor and beam is perpendicular to tooth

A

elongation

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29
Q

if you shorten source to receptor what happens
a. increases sharpness
b. decreases magnification
c. decreases sharpness
d. increases magnification

A

c and d

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30
Q

what ionization has the most effect
compton scattering
photoelectric
coherent

A

compton- most common
57-62%

31
Q

-can ionize multiple
-interacts with outer shell electron
-xr photons continue in diff directions with less energy creating scatter until all energy lost

A

compton scatter ionization

32
Q

-only ionizes
-absorbed by inner shell electron
-collides and loses energy

A

photoelectric

33
Q

-excites but does not ionize
-xr photon of low energy interact with outer orbital electron and change direction but no photoelectric produced

A

coherent

34
Q

lady has colon cancer and thus had radiation. however, her 2 kids are at increased risk. this affected

A

germ cells

35
Q

what is the most lethal part of hematopoetic syndrome

A

sepsis

36
Q

the effect only seen in the person effected, NOT future generation generations

A

somatic

37
Q

by federal law, a signal and light are required on every xray unit

A

true

38
Q
A
39
Q

how many Gy needed for treatment of
solid tumors
lymphomas
intraoral cancer

A

solid tumors 60-80 Gy
lymphomas 20-40 Gy
intraoral cancer 50 Gy

40
Q

operating kV listed below, what size of filtration do you need
<50=
50 to 70=
>70=

A

<50= 0.5mm
50 to 70= 1.5mm
>70= 2.5mm

40
Q

full time xray operator needs to have what on their person at all times

A

dosimeter
personal monitor device

41
Q

in x-radiation, absorbed dose is ______to equivalent dose

A

equal

equivalent dose Ht= QF of 1 x absorbed dose Dt

42
Q

in x-radiation, absorbed dose is _____ to the effective dose

A

less

effective dose E= sum of absorbed dose Dt X Wt (tissue weighing factor)

43
Q

what happens when you increase mA

A

increase density (and increase # of photons)

44
Q

alpha particles have _____charge and a _____ LET than a proton

A

larger
larger

aplha +2 (high LET)
beta +1
beta -1
neutron 0
electron -1
proton +1
xray NO CHARGE (low LET)

45
Q

this reduces the amount of scatter radiation exposing film (and improves contrast)

A

grid
(image inhancer)

46
Q

radiograph sensor sizes

A

0= pediatric
1= anterior PA, pediatric BW
2= adult PA, adult BW, pedi occlusal
3= not used, longer BW
4= adult occlusal

47
Q

what does rectifier do

A

converts AC to DC
(convert alternative current to direct current)
AND
moves from cathode to anode

48
Q

multiple line ruler picture that shows

A

quantitative image analysis

49
Q

if you increase tube voltage, it will _____the x-ray quantity and _____the quality

A

increase
increase

50
Q

otto walkhoff

A

first dental radiograph

51
Q

what occurs if images are compressed on computer and there is no space

A

decrease in storage

52
Q

what does atomic number measure

A

protons

53
Q

alpha particles have a ____LET, which means it has a ____mass and a ____velocity

A

higher LET
higher mass
lower velocity

54
Q

what does tungsten target do

A

transform the kinetic energy of the colliding electrons into x-ray photons

55
Q

what do you do to increase magnification

A

BAD, dont want this
decrease source to object length
or
increase object to receptor length

56
Q

what would increasing the sensor to object distance and decreasing the object to receptor distance do?

A

minimize magnification

57
Q

what is the probability of occurence

A

stochastic (frequency)

58
Q

what is the interaction of xray with matter called___radiation

A

ionizing

59
Q

what is the indirect x-ray photons absorbed by to create free radicals

A

water

60
Q

what are examples of threshold effects?

A

this is deterministic
xerostomia
erythema
cataracts
fetal development

61
Q

as the oxygen content ____, it ____in the sensitivity

A

increases
increases

62
Q

what two things are important factors in radiosensitivity

A

younger age and increase of oxygen content

increase total dose
increase doe rate
cell
area exposed
cell type and function

63
Q

what is the max radiation dose of a pregnant dental hygienist

A

5mSv

64
Q

what is it called when you do whatever you can to reduce the radiation dose

A

ALARA

ALADA- as low as dx possible

65
Q

if operating kV is equal to 70 and the aluminum filtration is 1.5mm, what needs to occur?

A

nothing needs to occur because kv of 50-70 is adequate with aluminum filtration size of 1.5mm

kV <50 .5mm
50-70 1.5mm
>70 2.5mm

66
Q

what is the most effective way to reduce the dose

A

recessed x-ray tube

a. xray tube head (mandated)
b. filtration (aluminum filter)
c. collimation (lead)

67
Q

another question about effective way to reduce something

A

speed of sensor (want quicker)

68
Q

where do you want to place the bacscatter shield at

A

at the end of the PID(closest to patient)

69
Q

what do you do with new patient that has a lot of things done to them. what dental radiographs do you use?

A

full mouth series

70
Q

what occlusal radiographs do we use

A

PSPP

71
Q

cross sectional has ____ posterior coverage and ___angle

A

more coverage
less angle

72
Q

what occlusal radiographs do we use

A

film and PSPP

73
Q

secondary photons resulting in image degradation when doing extraoral imaging

A
74
Q

what is the point of waters radiograph

A

see the maxillary sinus

75
Q
A

ORAL RADIOLOGY EXAM 2 (16 decks)

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