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Physics > Test 2 study guide > Flashcards

Test 2 study guide Flashcards

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1
Q

List the layers of the radiographic film?

A

super coat
emulsion
adhesive layer
film base

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2
Q

What is the thickness of the film base?

A

150 to 300 um

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3
Q

film base is made of what material?

A

polyester (plastic)

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4
Q

the emulsion is made of what material?

A

silver halide cystals suspended in gelatin

silver halide contains 90-99% silver bromide and 1-10% of silver iodide.

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5
Q

which film is faster and why?
A)single emulsion film
B)double emulsion film

A

double emulsion, that is, an emulsion is layered on either side of the base. this double layering is attributable primarily to the the efficiency conferred by the use of two screens to expose the film from both sides. this produces twice the speed that could be attained with a single emulsion film even if the single emulsion were made twice as thick.

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6
Q

which film gives better detail and why?
A) single emulsion film
B) double emulsion film

A

single emulsion gives better detail because it is slower–mammogram is single emulsion

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7
Q

which film causes more radiation dose to patients and why?
A) single emulsion film
B) double emulsion film

A

single emulsion because it is slower

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8
Q

what is sensitivity center or sensitivity speck?

A

physical imperfections in the crystal lattice of the emulsion layers occur during the film manufacturing process.
each sensitivity specks serves as electron trap, trapping electrons lost by the bromide when x-ray or light exposure occurs
therefore sensitivity specks are negativity charged.
since sensitivity specks are negatively charged, the positive silver ions that are liberated from bromide are attracted to them.
every silver ion that are attracted to an electron becomes neutralized to metallic silver
the more x-ray or light exposure, the more electrons and silver ions available
several sensitivity specks with many silver ions attracted to them become latent image centers.
for a latent image center to appear it must contain at least three sensitivity specks that have at least three silver atoms each.

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9
Q

what is spectral matching?

A

matching the spectral sensitivity of the film with spectral emission of the intensifying screen increases the speed of the image receptor
a film that is sensitive to blue color must be placed with an intensifying screen that produce blue light.

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10
Q

what filter is best for blue sensitive film?

A

amber color filter
transmit wavelengths longer than 550 nanometer
(above blue region)

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11
Q

what filter is best for green sensitive light?

A

red color filter
transmits wavelengths longer than 600 nanometer.
red is suitable for both blue and green lights.

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12
Q

what is the ideal temperature and humidity to store film?

A

68 F

40-60% humidity

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13
Q

what will be the effect of storing a film at high temperature?

A

increased heat causes fog

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14
Q

what will be the effect of storing a film at low humidity?

A

causes static artifact

tree, crown, smudge

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15
Q

what is the name of the image after exposure and before processing?

A

latent image

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16
Q

list the layers of the intensifying screen

A

protective layer
phosphor layer
reflecting layer or absorbing layer
base

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17
Q

what are the phosphors used to manufacture intensifying screens?

A

calcium tungstate
zinc sulfide
barium lead sulfate
oxyfulfide of rare earth elements

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18
Q

phosphorescence

A

occurs when phosphors continue to emit light after the x-ray exposure has stopped

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19
Q

fluorescence

A

refers to the ability of phosphors to emit visible light only while exposed to x-rays

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20
Q

name the phosphors used in rare earth screens

A

gadolinium
lanthanum
yttrium

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21
Q

what is screen lag and how does it affect the image?

A

the phosphorescence in an intensifying screen

it affects the image by causing fog on the film

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22
Q

how do you check for screen film contact?

A

between each screen and cassette cover is some sort of compression device, such as radiolucent plastic foam, which maintains close screen film contact when the cassette is closed and latched.

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23
Q

what happens during developing?

A

the latent image is converted to visible image

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24
Q

what happens during fixing?

A

removes remaining silver halide from emulsion and hardens gelatin

25
Q

why is fixing important?

A

when developing is complete, the film must be treated so that the image will not fade.
this stage of processing is fixing.
the image is fixed on the film
improves archival quality
archival quality refers to the permanence of the radiograph. the image does not deteriorate with age but remains the original stage.

26
Q

why is washing important?

A

removes excess chemicals

27
Q

what material is used as a fixing agent?

A

ammonium thiosulfate

28
Q

what are the prime exposure factors?

A

kVp
mA
Exposure time
distance

29
Q

what factor control radiographic contrast?

A

kVp

30
Q

what factor controls radiographic density?

A

mAs

31
Q

does kVP influence radiographic density?

A

kVp and density are directly related

32
Q

does mAs influence radiographic contrast?

A

inversely; mass alters the contrast

33
Q

what will be the effect of using kVp to manipulate the density?

A

will decrease the contrast

34
Q

what is the definition of optical density?

A

degree of blackening on a radiiograph

35
Q

what is the definition of contrast?

A

degree of difference between the light and dark areas of a radiograph

36
Q

what factor controls the radiation penetrability?

A

kVp

37
Q

what factor controls the energy of the x-ray beam?

A

kVp

38
Q

what factor controls the number of photons produced?

A

mA

39
Q

what change in quality occurs when changing the mA?

A

x-ray quality remains fixed with a change in mA

40
Q

how can you reduce motion blur?

A

short exposure time

41
Q

how does distance affect radiographic quality?

A

no affect on radiographic quality

42
Q

what is the effect of changing the focal spot size for a given kVp/mAs setting?

A

does not change the x-ray quantity or quality

43
Q

what is the purpose of filtration?

A

to block or filter out some of the wavelengths in the x-ray spectrum

44
Q

what is inherent filtration?

A

refers to any filtering done by components of the x-ray tube assembly (0.5mm) al

45
Q

what is the total filtration?

A

Inherent plus added filtration 2.5mm al total

46
Q

what is the function of a compensating filter?

A

provide uniform density on the image when radiographing non-uniform items

47
Q

a compensating filter is also known as

A

wedge or trough
wedge for the spine
trough for the chest

48
Q

what change will occur in radiation quantity when changing from a half wave rectification to a full wave rectification?

A

same radiation quality

double the quantity on full wave rectified generators

49
Q

radiographic technique charts are based on what type of patients?

A

sthenic

50
Q

Name the 4 types of body habitus

A

hypersthenic 5%
sthenic 50%
hyposthenic 35%
asthenic 10%

51
Q

identify the radiolucent pathologies

A

destructive pathology

52
Q

identify the radiopaque pathologies

A

constructive pathology

53
Q

the mAs value must be changed ?% to produce a perceptible change in OD.

A

30%

54
Q

the kVp must be changed ?% to produce a perceptible change in OD.

A

4%

55
Q

what will be the effect on density if you increase the kVp by 15%?

A

will double the OD

56
Q

properly exposed rib radiograph demonstrate

A

short scale (low kvp)

57
Q

properly exposed chest x-ray demonstrate

A

long scale (high kvp)

58
Q

high contrast is also known as

A

short scale

59
Q

low contrast is also known as

A

long scale

Physics (7 decks)

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