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Physics C/O 2026 > Physics Chapters 5-6 Santanna > Flashcards

Physics Chapters 5-6 Santanna Flashcards

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1
Q

Intensity may be reported in various ways with respect to

A

space and time

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2
Q

_____ is a key parameter with regard to bio effects

A

Intensity

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3
Q

_____ is being the most relevant to tissue heating

A

SPTA ( spatial peak temporal average)

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4
Q

_____ is greater than average

A

peak

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5
Q

What is the highest intensity?

A

SPTP (spatial peak temporal peak)

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6
Q

What is the lowest intensity?

A

SATA (spatial average temporal average)

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7
Q

positive decibels means intensity is getting

A

bigger

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8
Q

negative decibels means intensity is getting

A

smaller

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9
Q

What is the decrease in strength of a sound wave as it travels? What is the units?

A

attenuation, dB

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10
Q

True or false? The further sound travels, the weaker it gets or the move it attenuates

A

True

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11
Q

In soft tissue, ___ frequencies attenuate less.

A

lower

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12
Q

This is reflection from a smooth reflector, like a mirror. It returns in one direction.

A

specular reflection

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13
Q

What happens when propagating sound energy strikes a boundary between two media and some energy returns to the probe?

A

reflection

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14
Q

The reflection of sound back in the general direction of the probe but in a number of directions

A

diffuse reflection or backscatter

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15
Q

What is the distrubtion of sound randomly in all directions.

A

scattering

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16
Q

Does higher frequency scatter more?

A

YES

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17
Q

What is the equation for rayleigh scattering and the definition?

A

organized and omidirectional

rayleigh scattering is proptional to frequency^4

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18
Q

what is the amount of attenuation per centimeter is called? What are the units?

A

attenuation coefficient and dB/cm

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19
Q

attenuation coefficient is directly related to

A

frequency

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20
Q

The distance sound travels in a tissue that REDUCES the intensity of sound to one-half of its original value
the units are

A

half value layer thickness

cm

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21
Q

What does half value layer thickness depend upon?

A

the medium and frequency of sound

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22
Q

Thin half value means

A

higher frequency sound media with high attenuation rate

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23
Q

Thick half value means

A

low frequency sound media with low attenuation rate

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24
Q

What is calculated not measure? A number associated with a medium

A

Impedance

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25
Q

What is the units for impedance?

A

Rayls (Z)

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26
Q

A normal incidence

A

perpendicular
orthogonal
right angle
ninety degrees

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27
Q

anything other than a 90 degree angle

A

oblique incidence

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28
Q

Intensity of the sound wave prior to striking a boundary

A

incident intensity

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29
Q

the intensity after striking the boundary that turns around and reflects back to the probe

A

reflected intensity

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30
Q

the intensity that after striking the boundary continues on in the same direction

A

transmitted intensity

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31
Q

The % of the US intensity that bounces back when the sound strikes a boundary

A

Intensity Reflection Coeficient (IRC)

32
Q

Is IRC and ITC unitless?

A

True

33
Q

% of incident intensity that after striking the boundary continues on in the same direction

A

Intensity Trasmission Coefficent

34
Q

What occurs if the two media at the boundary have different acoustic impendaces ?

A

reflection

35
Q

Will transmission and reflection with oblique incidence occur?

A

It may or may not

36
Q

Materials used for the matching layer of a transducer must have an impedance level between the

A

skin and PE element

37
Q

What is the function of the damping material of an ultrasound transducer

A

reduces “ringing” of the PZT

38
Q

A ____ MHz transducer will have the thinnest element
a. 2 mhz
b. 12 mhz
c. 5 mhz

A

12

39
Q

A frequency of the transducer depends primarily on the

A

element thickness

40
Q

While scanning soft tissue, the reflected wave returned to the transducer in 5usec. How far away is the reflector?

A

4 cm

41
Q

Range equation is used to determine the

A

distance to the reflector

42
Q

damping of the sound beam

A

reduces the SPL

43
Q

What is defined as the range of frequencies contained in the US pulse.

A

bandwidth

44
Q

The use of backing material would result in all the following expect:
a. wider bandwidth
b. lower quality images
c. decreased sensitivity
d. lower Q factor

A

b

45
Q

if you change from a transducer with 20 mm crystal thickness to one with 40 mm thickness, the frequency of the sound produced will:

A

half

46
Q

imaging probes have a ___ q factor and a ____ bandwidth

A

low and wide

47
Q

as transducer frequency ____ the q factor ___

A

increases and increases
they are directly related

48
Q

a larger bandwidth leads to

A

improved axial resolution

49
Q

as the q factor increases the bandwidth

A

decreases/ narrows

50
Q

What is time of flight?

A

time it takes for a pulse to travel to and from the transducer and the reflector

51
Q

the time of flight and the distance the sound travels are ____ related

A

directly

52
Q

what is a property of material to create a voltage when pressure is applied or when the material is mechanically deformed.

A

piezoelectric effect

53
Q

Man made peizoelectric materials

A

lead zirconate titanate (PZT)
barium titanate
lead titanate

54
Q

natural piezoelectric materials

A

quartz and tourmaline

55
Q

What degrees can PZT be destroyed at?

A

360 C 680 F
this is why we can’t autoclave probes

56
Q

what is the complete destruction of all living microorganisms by means of exposure to heat, chemicals, or radiation.

A

sterilization

57
Q

using a chemical agent to reduce or eliminate infectious organisms on probes

A

disinfection

58
Q

What is HLD?

A

higher level disinfecting (vaginal probes)

59
Q

Can we use alcohol as a disinfectant?

A

NO

60
Q

What transducer component protects the internal components from damage, and insulates the patient from electrical shock.

A

case

61
Q

What is active element?

A

piezoelectric crystal that is also called PZT, ceramic, or crystals.

62
Q

How thick is active element or PZT?

A

1/2 wavelength thick

63
Q

Backing element/ Damping element is made of

A

epoxy resin impregnated with metal powder

64
Q

When a emitted sound is dampened, what happens

A

it is short in duration and length

65
Q

crystal damping enhances

A

axial resolution

66
Q

where is the matching layer postioned

A

in front of the PZT at the face of the transducer

67
Q

how thick is the matching layer

A

one-quater wavelength thick

68
Q

does CW probes need backing/damping materials

A

NO

69
Q

Impedences

A

PZT > Matching layer> gel> skin

70
Q

what are imaging transducer characteristics

A

damping is effective
short pulse length and duration
low sensitivity
wide bandwidth
low q factor
decreased output power

71
Q

no damping and narrow bandwidth

A

high q factor (CW)

72
Q

damping and wide bandwidth

A

low q factor

73
Q

characteristics of high frequency pw imaging transducers

A

thinner, PZT crystals
PZT with higher speeds

74
Q

characteristics of low frequency pw imaging transducers

A

thicker PZT crystals
PZT with lower speeds

75
Q
A

Physics C/O 2026 (12 decks)

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