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X-Ray Tech > Test 3 Unit 3 - Cont'd > Flashcards

Test 3 Unit 3 - Cont'd Flashcards

1
Q

Power. Responsible for penetrating anatomy, responsible for producing scatter. higher=more scatter, more penetration.

A

kVp

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2
Q

radiation interacting with matter that travels in all different directions and has experiences loss of energy. Fogs an xray, leading to decreased contrast of the image. radiographic noise.

A

scatter

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3
Q

5 xray interactions with matter

A

Compton’s Effect, Photoelectric Effect, Classical Scatter, Pair Production, Photodisintegration

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4
Q

in the diagnostic energy range (40-150kEv), clinically significant interactions with matter

A

Compton’s and photoelectric effects

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5
Q

most of the scatter produced is this. xrays interacting with matter deflect off outer shell electrons of the material, lose energy, and change direction.

A

Compton’s Effect

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6
Q

the probability that an xray photon will scatter is contingent upon the….

A

energy of the xray and density of the object

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7
Q

xrays are absorbed. xrays lose all of their energy through an ionization interaction with an inner shell electron. causes differential absorptionof xray tissues, thereby producing subject contrast. The elctron has been absorbed causing white on the film.

A

photoelectric effect

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8
Q

As kVp increases, penetration and scatter_______

A

increase

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9
Q

What do high energy xrays tend to do?

A

pass through matter

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10
Q

What low energy xrays tend to do?

A

become totally absorbed

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11
Q

What do mid to high energy xrays tend to do?

A

scatter

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12
Q

The larger the subject ___________________

A

the more kVp needed = the more scatter produced

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13
Q

Xray absorption is also contingent upon…..

A

xray energy and tissue density

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14
Q

Absorption is most likely to occur when…….

A

the energy of the xray is equal to or slightly greater than the binding energy of the electron it interacts with

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15
Q

Greater energy will cause….

A

the ray to scatter or penetrate straight through

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16
Q

Increased absorption is due to

A

more dense tissues

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17
Q

results from low energy xrays interacting with matter

A

classical scatter (aka Coherent, Thompson, or Rayleigh)

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18
Q

These xrays have insufficient energy to cause ionization, but vibrate the atom. Vibrating electrons produce a summative xray with the same wavelength as the incident xray, but in a different dierction

A

classical scatter

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19
Q

occurs with xrays in the MeV (milivolt) range. It interacts with the nucleus and the energy is converted into matter in the form of two particles, a positron and a negatron. The two oppositely charged particles annihilate each other releasing 2 .51 MeV gamma rays in opposite directions

A

Pair Production

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20
Q

occurs when a 10 MeV xray invade a nucleus. The energy is absorbed by the nucleus and nuclear fragments are emitted

A

photodisintegration

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21
Q

Conditions that contribute to scatter radiation production

A

high kVp, thick soft tissue (water density), large field size

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22
Q

Scatter control methods for contrast improvements

A

optimum kVp, field size control (collimation), scatter-absorbing grids, air-gap technique, recumbent radiography

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23
Q

affects radiographic density and contrast

A

scatter-absorbing grids and air-gap technique

24
Q

selective lead strip filter, placed between the patient and the film, designed to absorb scatter radiation. Gustave Bucky in 1913

A

scatter absorbing grids

25
Q

Were are grids installed?

A

inside the front cover of the Bucky

26
Q

When is a grid used?

A

when the patient part measures greater than 10 cm or when using techniques above 70 kVp

27
Q

how well the grid cleans scatter

A

grid ratio

28
Q

To reduce scatter radiation, the scatter radiation enters the lead strips…

A

at an angle where it is absorbed and does not reach the film.

29
Q

Some xray photons, having interacted with the patients body…

A

change direction, loose energy, and have the potential to reach the film entering from a different direction which degrades the quality of the image

30
Q

the orientation of lead lines follow a ….

A

linear, cross hatched, or rhombic cross hatched pattern

31
Q

What is the grid made of?

A

very thin lead lines separated by thin strips of aluminum or carbon fiber

32
Q

two types of linear grid

A

parallel and focused

33
Q

the lead lines are parallel to each other across the grid plate creating an infinity focus.

A

parallel grid

34
Q

Because the xray beam diverges from the focal spot, parallel grids typically produce images with reduced exposure on the sides called _______.

A

grid cutoff

35
Q

Peripheral cutoff of exposure. Grid cutoff appears as underexposure on film.

A

Parallel lead lines ( we don’t use)

36
Q

grid specifications

A

grid ratio, grid frequency, grid radius, grid focal range

37
Q

Grid ratio

A

is the measure of the height of the lead strips divided by the distance between them. h/d

38
Q

the higher the grid ratio, the _________ the contrast

A

higher

39
Q

common chiropractic grid ratios

A

8:1 and 10:1 and 12:1

40
Q

12:1

A

focused grid used with a single phase generator

41
Q

10:1

A

focused grid used with a high frequency generator

42
Q

a measure of the number of lead lines per inch or centimeter the more present the less grid lines on the film but patient does increases

A

grid frequency

43
Q

every focused grid is manufactured to a set distance

A

grid radius

44
Q

the set distance without a significant amount of peripheral cutoff

A

grid focal range.

45
Q

xray outside the range _________ peripheral cutoff

A

increases

46
Q

removing scatter = _______ film density

A

reduced. removing gray layers which affects the overall darkness of the film.

47
Q

decreased collimation = ________ density

A

decreased

48
Q

scatter results from….

A

primary xray interacting with matter

49
Q

smaller field size = ______ scatter

A

less. because less primary xrays are interacting with tissues

50
Q

using smaller films and tight collimation

A

spot filming

51
Q

if the patient part is moved a short distance away from the film, some of the scatter radiation exiting on the film side of the patient will miss the film

A

air-gap technique (not diagnostic)

52
Q

air gap technique produces a ______ scale contrast

A

shorter 10” gap maximum

53
Q

recumbent radiography

A

laying patient down decreases the diameter of the patient which allows for less kVp=less scatter. also helps stabilize a patient

54
Q

not often used in chiropractic. stretched across bucky to compress abdominal tissues with the patient in an upright position

A

compression band

55
Q

used to cover areas of film on film cassettes where multiple exposure are made on a single film

A

lead vinyl blockers

X-Ray Tech (4 decks)

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