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mental dental > MD RADIOLOGY > Flashcards

MD RADIOLOGY Flashcards

1
Q

steps of how an x-ray is made

A

electricity -> Heat -> electrons -> xrays

xrays produced when high speed electrons hit metal targets

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2
Q

strongest to weakest light

A

gamma > xray > UV > visible light > infrared (UV) > microwave > radio

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3
Q

visible light is carried by what?

A

photons

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4
Q

XRAY emits a beam to the receptor. person standing in the middle between receptor and PID ( position indicating device) is called

A

attenuation

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5
Q

give a summary of how xray works

A

1) electricity generates heat
2) creates electrons
3) shoot out of PID ( tube head) to the receptor
4) attenuation ( object standing between) gets hit with radiation and projects it to receptor

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6
Q

what has higher energy, shorter or longer wavelength?

A

SHORTER (gamma)

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7
Q

2 types of ionization radiation?

A

ELECTROMAGNETIC
: electric and magnetic field ( radio waves, gamma, xray,micro, etc: )

PARTICULATE:
atomic nuclei or subatomic particles moving HIGH VELOCITY ( alpha and beta particles)

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8
Q

2 types of XRAY production ?

A

Bremsstrahlung ( brem: to break / rahlung: radiation)

Characteristic

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9
Q

what is brehmsstrahlung ?

A

PRIMARY source of x ray photons

electrons strikes target and brakes giving off energy

generates CONTINUOUS spectrum of energy

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10
Q

what is CHARACTERISTIC xray production

A

SECONDARY source xray photons

e knocks into another e and drop into lower energy orbital

emits photon of SPECIFIC energy

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11
Q

what is the primary and secondary source of xray photons?

A

Primary: bremsstrahlung

secondary: characteristic

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12
Q

what does cathode do?

A

tungsten filament produces electrons

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13
Q

what does anode do?

A

tungsten target converts electrons to xray photons

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14
Q

MATCH MATERIAL WITH FUNCTION:

copper / molybdenum / lead / glass / aluminum

focuses beam onto small focal spot
dissipitates heat 
insulation 
filtration 
collimation
A

MOLYBDENUM: focusing cup focuses beam onto small focal spot

copper: dissipitates heat
glass: insulation
aluminum: filtration
lead: collumiation

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15
Q

intensity VS Energy

  • electrons and photons ?
  • how images look ?
A

INTENSITY
: QUANTITY of e/ #NUMBER of photons
: DENSITY: darkness of image

ENERGY:
QUALITY of e / ENERGY of photons
CONTRAST: difference in gray value

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16
Q

2 images are shown side by side. the R one is darker than the L one. describe their contrast and density

A

Darker One: higher intensity = higher density

lower energy = lower contrast

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17
Q

exposure time (s) affects what?

A

INTENSITY = density = darkness of image

lighter image has less exposure time which = less density

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18
Q

how does exposure time correlate to photons?

A

more time = more photons

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19
Q

tube current ( mA) effects what?

A

affects INTENSITY :

too much = too dark (too much photons reach sensor)

^ mA = ^ photons= ^ intensity = darker

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20
Q

tube potential (kVP) affects what?

A

affects INTENSITY and ENERGY !!!!! bOTH

too high = too gray
too low= too light

think about it… decreasing kVP increases contrast ( LIGHTER) and increases INTENSITY ( density)

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21
Q

what does filtration do to photons and involves what element ?

A

removes lower energy photons from beam to reduce exposure

aluminum

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22
Q

which is similair to beam hardening ?

filtration
tube potential
tube current
exposure time

A

filtration

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23
Q

collimation involved what element? how does it affect patient exposure ?

A

LEAD

reduces beam size to reduce exposure

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24
Q

what is the best shape collimation?

A

rectangular

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25
Q

how does distance correlate to photon emission and quality of the image?

A

^ distance: less photons = darker image

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26
Q

what is source to object distance? (SOD)

A

how far object is from xray source

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27
Q

what is object to image distance?

A

distance betweem object and sensor behind it

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28
Q

what happens to intensity when Source to object distance increases?

A

intensity decreases ( inverse square log)

29
Q

quality of image when object to image distance gets smaller?

A

gets sharper

30
Q

what is source to image distance ?

A

from xray source to sensor/film

OID + SOD

31
Q

what source to object distance and object to image distance do we want?

A

max SOD

minimum OID

32
Q

what is umbra?

A

shadow behind an image ( no light gets to)

33
Q

what is penumbra?

A

side shadow

34
Q

how does focal spote size and penembra correlate ?

A

smaller FSS = lower penebra + sharper the image

35
Q

why does image have poor contrast?

A

high kvp / low filtration

36
Q

what is coherant scattering?

how does it affect contrast?

A

photon contact OUTER e

decreases contrast !

37
Q

what is photoelectric absorption?

what does it do to contrast?

A

incident photon contacts INNER e and forms ion pair

increase contrast

38
Q

what is compton scattering?

whats it do to contrast?

A

photon contact OUTER e and forms ion pair

dec contrast

39
Q

what is deterministic effect?

A

responses which increases in severity with increased dose . have threshold dose that needs to be met before something bad happens

40
Q

what is stochastic effect?

A

effects that happen by chance do not have threshhold dose ( linear no-threshold model)

41
Q

Direct vs inderest radiation chemistry

A

Direct:

  • DIRECTLY affecting biologic molecules ( protein,dna)
  • 1/3 biologic effect

Indirect:
- ionizing radiation converts water to FREE RADICALS alter biologic molecules (AFFECTS ENVIRONMENT SURROUNDING DNA such as salts, water, protein, O2) WHICH EFFECTS DNA
2/3 of biologic effects

42
Q

which cells are more radiosensative ?

A

mitotically active ( sperm cells)

43
Q

how many mSv is background radiation and mostly from what source?

A

3.1

RADON

44
Q

manmade radiation how many mSv and from what source?

A

3.1

MEDICAL IMAGING

45
Q

what is the average exposure to individuals living in US?

A

6.2 mSv ( 3.1 background + 3.1 manmade)

46
Q

occupational exposure limits how many mSv per year?

A

50

47
Q

when looking at radiograph and the image has radiolucent properties this means what?

A

R/L = dark

photons pass through tissue to reach film

48
Q

when looking at radiograph and the image has radio opaque properties this means what?

A

r/o = light

photons are attenuated (blocked) do not reach film

49
Q

what color would film be if took an image of nothing?

A

BLACK

photons pass right through

50
Q

what is film emulsion made of?

A

silver halide crystals

51
Q

what happens during DEVOLPMENT stage of film?

A

silver atoms turn black

52
Q

what are the 4 steps of chemical film processing?

A

developing
fixing
washing
drying

53
Q

during developer solution what is the first electron donor that reduces silver ions to metalic silver at latent image site ?

A

PHENIDONE

54
Q

during developer solution, what provides an electron to reduce oxidized phenidone to origingal active state>

A

hydroquinone

55
Q

what happens during FIXING STAGE of chemical processing >

A

remove undeveloped silver halide crystals from emulsion

56
Q

what is the chemical in fixer solution that remove silver halide crystals ?

A

ammonium thiosulfate

57
Q

what is PSP plates made of ?

A

Barium fluroihalide

58
Q

what is CCD ( digital sensor dexis) made of ?

A

silicone

59
Q 
Film VS digital
better contrast resolutin?
spatial resolution?
detector latitude ?
detector sensitivty ( dose required to achieve standard gray level?)
A

contrast: film
s[atial: film
Detector latitiude : PSP
Sensitivity: CCD half F speed film

60
Q

fastest FIlm speed and slowest speed

A

fastest: F
Slowest: A

A B C D E F

61
Q

most common radiographic error?

A

ELONGATION

62
Q

which view to see condyles better?

waters view
townes view
submentovertex view

A

townes ( angled PA Ceph of skull)

angle straight down middle of forehead

63
Q

which view to see paranasal sinus?

waters view
townes view
submentovertex view

A

waters ( angled PA ceph of skull)

angling x-ray diagnol to back of head

64
Q

which view to see zygomatic fractures

waters view
townes view
submentovertex view

A

submentovortex view

taking an image from floor straight up ti skull

65
Q

bisecting angle techniques is when x-ray beam ray is angled in what way?

A

perpendicular to imaginary bisector between long axis of tooth and long axis of receptor

66
Q

pano appears patient is smiling which way is his chin?

A

chin DOWN

67
Q

what does the filament do in xray?

A

made of tungsten

in the cathode PRODUCE E

68
Q

what does the anode and cathode produce ? what are they made of?

A

Cath: Electrons ( tungsten filament produces e)
Anode: Photons ( tung. electrons -> photons)

69
Q

what is the xray tubehead and Position indicating device?

A

tubehead is the bdy of the xray PID is the tube that comes off that body

mental dental (18 decks)

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