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Tri 4 - Radiography > Test 2 - part 2 > Flashcards

Test 2 - part 2 Flashcards

1
Q

mA’s

A

milliamperage per second

responsible for xray quantity

used to adjust optical density and contrast

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2
Q

if mA’s are too high

A

film will be overexposed

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3
Q

if mA’s are too low

A

film will be underexposed

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4
Q

kVp

A

kilovoltage peak

refers to amount of energy an xray beam possesses

controlled by electrical potential and voltage

related to degree of xray penetrability

responsible for xray quality

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5
Q

a change in __% in kVp is needed to notice visible film changes

A

4%

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6
Q

a change in _____% kVp is equivalent to 50% change in mAs

A

10-15%

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7
Q

____% change in mAs is required to observe changes in optical density

A

30

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8
Q

reducing time of exposure will result in ______ the patients radiation dose

A

reduce

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9
Q

relationship between mAs and kVp that results in production of equivalent image density

manipulates the tube voltage by the 10 kVp will result in same image density change by changing the mAs by 50%

A

10kVp rule

doesnt apply for radiographic images acquired at less than 60 kVp or greater than 100 kVp

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10
Q

blurring of the shadow of an image with lowering of sharp edges corresponding to object shape

increase in focal spot with increase ______

change in ______ is proportional with object film distance

increase film distance increases ______

A

penumbra

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11
Q

decrease in light or xray intensity is inversely proportionate to square of the distance of the object to the source

light xray exit as a cone and the intensity decreases due to spreading out effect

wavelength remains fixed

radiation intensity is inversely related to the square of th distance from the source

if distance is increased 2x the intensity is reduced by 1/4

when distance is cut by 1/2, intensity is increased by 4x

A

inverse square law

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12
Q

results with the cloud of electrons emitted from the cathode

A

thermionic emission

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13
Q

what 3 events occur as electron cloud approaches anode

A

cathodes electrons lose kinetic energy

99% of interaction of electrons at target result in heat production

remainder of electrons will produce bremsstrahlung or characteristic radiation

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14
Q

photon production increases with _____ in kVp

A

increase

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15
Q

at 60 kVp - only ____% are x photons

A

.5

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16
Q

at 100 kVp - ____% are x photons

A

1

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17
Q

occurs in tube

majority of xrays

electrons emitted from cathode hit the anodes target which contains a high atomic number Z

strong nucleic field of positive charged protons begin to project electrons

some projectile electrons change their course and deflect with some or all of their original kinetic energy being LOST

results in energy released as xray photons known as

A

bremsstrahlung radiation

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18
Q

german for breaking or slowed down radiation

A

bremsstrahlung

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19
Q

energy ranging from zero to maximum kinetic energy (Emax) when they hit the anode depending on nucleic field

continuous spectrum wiht peak 1/3 of Emax

A

bremsstrahlung radiation

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20
Q

occurs in tube

produced when a projectile electron interacts with inner K shell electrons

projectile electrons energy exceeds binding energy of K shell electron resulting in removal of the K electron from its orbit

outer L shell electron will fill the void

this results in energy released as

A

characterisitc radiation

21
Q

interaction is very specific, xray photon has specific energy = to difference in binding energies of orbital electrons - in diagnostic xrays, only the K characteristic xray emission is important

A

characteristic radiation

22
Q

each element has its characteristic electron binding energy

each characteristic xray will be different

effective energy of characteristic xrays is directly related to atomic number Z of particular element

A

characteristic elements

23
Q

energy of different photons emitted from xray tube

A

xray emission spectrum

24
Q

contains precise fixed energies and form descrete emission spectrum

A

characteristic xrays

25
Q

spectrum production varies between 0 and the highest energy peak of each photon

A

bremsstrahlung

26
Q

xray energy and wavelength are _____ related

A

inversely

27
Q

____% of energy is converted to heat and the other __% is converted to xray

A

99% - heat

1% - xray

28
Q

negatively charged, made of tungsten filament

filament gets heated and starts emitting its surface electrons through thermionic emission

A

cathode

29
Q

positve charged, made up tungsten disc

fast moving xrays interact with ____ causing interaction with K shell electrons producing characteristic radiation and/or interaction and deflection of projectile electrons with the nucleus causing bremsstrahlung

A

anode

30
Q

energy in transit, either as particles or electromagnetic waves

A

radiation

31
Q

characteristic of various materials to emit ionizing radiation

A

radioactivity

32
Q

removal of electrons from an atom

high energy radiations when interacting with matter

A

ionization

33
Q

as wavelength decreases.. energy and ionizing potential will

A

increase

34
Q

form of man made electromagnetic radiation

A

xray

35
Q

produced from the xray tube

high voltage electrons produced by cathode during thermionic emission

the electrons interact with the anode resulting in production of

A

xrays

36
Q

penetrate most matter

invisible

no charge

makes compounds emit light

cause ionization

A

xrays

37
Q

photoelectric absorption is related to atomic number

if atomic number increases

the photoelectric absorption

A

increases

38
Q

most likely to occur with lossely bound outer shell electrons

A

compton scatter

39
Q

most likely to occur within inner shell electrons, with tightyl bound electrons

when xray energy is higher than electron binding energy

A

photoelectric absorption

40
Q

as atomic number increases

compton scatter _____

A

does not change, no effect

41
Q

as mass density increases

compton scatter _____

A

increases

42
Q

creates fogging and lower image contrast

A

compton scatter

43
Q

occurs because of compton scatter, photoelectric effect, and xrays transmitted through patient

A

differential absorption

44
Q

opaque

matter obstructs the transmission of radiant energy

when xrays are obstructed the film appears light - like bone

A

radiopaque

45
Q

non opaque

being permeable to radiation/xrays

when xrays are not absorbed and obstructed the film appears dark - like air

A

radiolucent

46
Q

differential absorption increases as kVp is ______

A

reduced

47
Q

process by which radiation loses power as it travels through matter and interacts with it

beam attenuation is the basis of contrast

A

exponential attenuation

48
Q
A

Tri 4 - Radiography (8 decks)

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