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Rad tech subjects > Physics Ch 14,16,17 > Flashcards

Physics Ch 14,16,17 Flashcards

1
Q

Location of the rod and cone cells

A

Cones- fovea centralis

Rods- remainder of retina

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2
Q

Which cells control photopic (daylight) vision

A

Cone cells

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3
Q

Which cells require relatively bright light to function

A

Cone cells

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4
Q

Which cells are sensitive to yellow light

A

Cone cells

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5
Q

What cells have a higher visual acuity?

A

Cone cells

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6
Q

What cells control scotopic (night) vision

A

Rods

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7
Q

What cells are sensitive to low light levels

A

Rods

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8
Q

Humans are unable to perceive colors in extremely low-light situations because of this

A

Rod cells are more sensitive to green light

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9
Q

Glare

A

When bright light causes temporary blindness in both humans and animals

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10
Q

Where does human image conversion occur?

A

In the rod and cone cells

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11
Q

What parts of the eye gathers and focuses light?

A

Lens
Iris
Cornea
Aqueous humor

LICA

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12
Q

What part of the eye converts images to nervous impulses?

A

Fovea centralis. Special cells of the retina

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13
Q

What part of the eye transmits impulses to the brain?

A

Optic nerve

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14
Q

What is the primary job of Rod and cone cells of the eye?

A

Image conversion ( in the retina)

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15
Q

Which cells in the eye are sensitive to yellow light?

A

Cones

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16
Q

What causes colorblindness?

A

A lack of cones sensitive to a particular color or colors

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17
Q

Most cones are located in the ______ ________in high concentration

A

Fovea centralis

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18
Q

Cones can detect changes in brightness which is also known as__________.

A

Contrast perception

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19
Q

Rods are sensitive to as little as ______photons

A

15

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20
Q

Rod cells function by photosensitization of ____________

A

Rhodopsin

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21
Q

Attenuation

A

Reduction in the total number of X Ray photons remaining in the beam after passing through a given thickness of material (patient).

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22
Q

Remnant beam (exit beam)

A
  • The beam that comes out of the patient
  • less intense than the entrance beam
  • contains radiologically significant info needed by radiologist to make diagnosis
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23
Q

When the patients thickness is increased the attenuation and exposure factors (increases/decreases)

A

Increases

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24
Q

X rays are attenuated exponentially, what does that mean?

A
  • reduced by a certain percentage for each given thickness of material they pass through
  • never reaches 0, each succeeding thickness of material reduces the # of photons by only a fraction of the previous amount.
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25
Q

When the patients thickness is increased the attenuation and exposure factors (increases/decreases)

A

Increases

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26
Q

high-atomic number materials attenuate (greater/lower) percentage of the beam then low-atomic number materials

A

Greater

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27
Q

Attenuation

A

Reduction in the total number of X Ray photons remaining in the beam after passing through a given thickness of material (patient).

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28
Q

Remnant beam (exit beam)

A
  • The beam that comes out of the patient
  • less intense than the entrance beam
  • contains radiologically significant info needed by radiologist to make diagnosis
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29
Q

When the patients thickness is increased the attenuation and exposure factors (increases/decreases)

A

Increases

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30
Q

high-atomic number materials attenuate (greater/lower) percentage of the beam than low-atomic number materials

A

Greater

31
Q

Higher atomic numbers have an (increase/decrease) in attenuation

A

Increase ( like bone + contrast agents)

32
Q

Bone produces (less/more) image receptor exposure

A

Less

33
Q

Density

A
  • The quantity of matter per unit of volume measured in kilograms per cubic meter.
  • how tightly the atoms of a given substance are packed together
34
Q

When density is increased, like with bone, attenuation is (greater/less) then other substances, such as lung tissue

A

Greater

35
Q

What is the greatest variable the radiographer faces when performing a radiographic procedure?

A

The human body and its tissues

36
Q

What does the body primarily consist of (at the atomic level) ?

A

Hydrogen, carbon, nitrogen, and oxygen

37
Q

Three different ways patients affect attenuation of image

A
  • patient thickness
  • tissue density
  • atomic number
38
Q

How does air appear on a radiograph, why?

A

Black. Air has significantly lower tissue density, so it absorbs fewer photons as they pass meaning more reach the IR.

39
Q

Where is air naturally present?

A

Lungs, sinuses, small amount in the GI tract and on an ABD X-Ray it’s seen in the stomach and colon

40
Q

How does fat appear on an image

A

Looks grey (perirenal fat capsule around the kidneys allows us to pick them out on an image)

41
Q

How does muscle appear on a radiograph?

A

Less grey than fat (psoas muscles on abdomen)

42
Q

What is a greater attenuater of the beam (fat/muscle)?

A

Muscle

43
Q

How does bone appear on a radiograph, why

A
  • White
  • Ca has a higher atomic #, and bone has a high density.
  • therefore, bone absorbs the beam and there is less exposure to IR
44
Q

There are no rods in the______ ________.

A

Fovea centralis

45
Q

A visual phenomenon involving the perception of extremely small or faint detail is _______ ________.

A

Threshold detection

46
Q

Minimizing background exposure and other artifacts such as visual noise….helps with ________

A

Threshold detection

47
Q

Why does the boundary effect occur?

A

Because the visual system has trouble perceiving contrast differences that are distant from each other

48
Q

The ________ ________occurs when the eye perceives a boundary. Each time there is a change in exposure, there is also a change intensity of impulses sent to the brain

A

Mach effect

49
Q

_________ __________ compresses the entire grayscale while making the boundary appear more distinct than it really is

A

Edge enhancement

50
Q

Contrast perception is greatly increased when a ________motion is used.

A

Scanning

51
Q

Because photosensitive cells in the eye can integrate a limited amount of information, eye movement avoids _________of the optical nerves.

A

Saturation

52
Q

In simple terms, define veil glare.

A

Brightlight scatters inside the eye and decreases contrast perception. (occurs when an intense bright light floods the eye directly)

53
Q

The fovea centralis creates a blind spot at a viewing distance of _________

A

9 inches

54
Q

Pattern recognition involves comparing…..____________

A

Mental images of patterns

55
Q

What is the true domain of the radiologists medical knowledge and competence?

A

Pattern recognition

56
Q

True or false?

Radiological positioning requires knowledge about shape and location of skeletal and soft tissue structures and an in depth understanding of their anatomical relationship

A

True

57
Q

How do radiological technologist achieve a 3-D view

A

By taking two images as close to 90° to one another as possible

58
Q

What are the dimensional views required for all exams?

A

Anterior to posterior, medial to lateral, superior to inferior

59
Q

Define attenuation;

A

Reduction of the total number of x-ray photons after passing through a given thickness

60
Q

The results of x-rays interacting with matter and being absorbed or scattered

A

Attenuation

61
Q

X-rays are attenuated exponentially, meaning….

A

They are reduced by a certain percent for each given thickness

62
Q

The __________ beam is altered as it passes through the patient

A

Incident

63
Q

What type of beam exits the patient and goes to the IR?

A

The remnant beam

64
Q

How tightly the Atoms of a given substance are packed together

A

Density

65
Q

What is the greatest variable the radiographer faces when performing a radiographic procedure

A

The patient

66
Q

At the atomic level, the body consists primarily of

______,_______,_______,_____.

A

Hydrogen, carbon, nitrogen, and oxygen

67
Q

What is the atomic number of calcium which is found in bones and teeth?

A

20

68
Q

What 4 major substances account for most of the variations and x-ray absorption in the body?

A

Air, fat, muscle and bone

69
Q

Which has a higher effective atomic number and greater tissue density? Fat or muscle

A

Muscle

70
Q

What 4 properties does the patient have an impact on when it comes to radiographic quality?

A

Density/image receptor exposure, contrast, recorded detail and distortion

71
Q

Subject contrast is…

A

The difference of densities on an image

72
Q

Subject density is….

A

The impact the patient has on the radiographic density/image receptor exposure

73
Q

Greater sharpness will result when the anatomical part is _________ to the image receptor

A

Closer

Rad tech subjects (16 decks)

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