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Physics > Bioeffects > Flashcards

Bioeffects Flashcards

1
Q

What are bioeffects?

A

Effects of sound on living tissue created by intense sound beam

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2
Q

What is a hydrophone/microprobe?

A

Similar to a small hypodermic needle with a tiny piece of PZT attached to its end; connected by a wire to an oscilloscope

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3
Q

What does a calibrated hydrophone provide?

A

Known relationship between the acoustic pressure signal and the voltage created by the PZT

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4
Q

What is the purpose of a membrane hydrophone?

A

Constructed from a very thin membrane of PZT plastic; detects intensity

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5
Q

What is the highest output power in ultrasound?

A

Pulsed Doppler

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6
Q

What is the lowest output power in ultrasound?

A

Gray scale imaging

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7
Q

What is the intermediate output power in ultrasound?

A

CF Doppler and M-mode

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8
Q

What is radiation force/feedback?

A

Force exerted on tissue by the sound beam; relates to power in the beam

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9
Q

What are the three devices that measure output of transducer by absorption?

A
  • Calorimeter
  • Thermocouple
  • Liquid Crystal
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10
Q

What is the function of a calorimeter?

A

Measures total power/entire intensity in a sound beam through absorption

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11
Q

What does a thermocouple do?

A

A tiny electronic thermometer that can measure intensity at a particular location

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12
Q

How do liquid crystals respond to temperature?

A

Change color based on their temperature

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13
Q

What is the risk-benefit relationship in clinical ultrasound?

A

Benefits to the patient must outweigh the risks of the exam

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14
Q

True or False: Diagnostic ultrasound has known harmful bioeffects.

A

False

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15
Q

Under what circumstances can bioeffects be beneficial?

A

Under controlled circumstances

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16
Q

What is the primary mandate regarding clinical ultrasound?

A

Benefits to the patient must outweigh the risks

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17
Q

What is dosimetry?

A

The science of identifying and measuring the characteristics of an ultrasound beam relevant to its potential for producing biological effects

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18
Q

What does ‘in vivo’ refer to?

A

Within the living body

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19
Q

What are the main characteristics measured by a hydrophone?

A
  • Period
  • PRP
  • PRE
  • PD
  • Amplitude
  • DE
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20
Q

What is the process of conversion of energy to heat called?

A

Thermal energy conversion

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21
Q

What is JAcousto-Optics?

A

Based on the interaction of sound and light

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22
Q

What is a Schlieren system used for?

A

A shadowing system that visualizes the shape of a sound beam in a medium

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23
Q

What is the term for biological effects studied outside the living body?

A

In vitro

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24
Q

What approach searches for a relationship between cause and effect in bioeffects research?

A

Mechanistic Approach

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25
Q

What approach searches for a relationship between exposure and response in bioeffects research?

A

Empirical Approach

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26
Q

What type of cavitation involves stable oscillating bubbles?

A

Stable cavitation

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27
Q

What is the term for the implosion of gaseous nuclei, bubbles, or contrast agents?

A

Cavitation

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28
Q

True or False: The strongest conclusions in bioeffects research are made when mechanistic and empirical conclusions agree.

A

True

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29
Q

What mechanism involves very high intensities causing genetic damage and cell death?

A

Nonthermal Mechanism

30
Q

What is the thermal index for soft tissue referred to as?

A

TIS

31
Q

What is the thermal index for bone referred to as?

A

TIB

32
Q

What is the thermal index for cranial bone referred to as?

A

TIC

33
Q

Fill in the blank: _______ is important in the research of bioeffects.

A

Bioeffect research

34
Q

What type of cavitation occurs at lower MI levels and involves oscillating gaseous nuclei?

A

Stable cavitation

35
Q

What type of cavitation occurs at higher MI levels and is characterized by bursting bubbles?

A

Transient cavitation

36
Q

What are the potential harmful bioeffects when the temperature rises from 37C by 2-4C for more than 50 hours?

A

Harmful bioeffects

37
Q

What can a temperature of 41C+ during a testicular exam cause?

A

Infertility

38
Q

True or False: Fetal tissues are more tolerant than adult tissue regarding temperature increases.

A

False

39
Q

What type of cavitation is also called normal or inertial?

A

Transient

40
Q

What occurs during transient cavitation that produces shock waves and very high temperatures?

A

Bursting bubbles

41
Q

What does the FDA regulate as the SPTA limit in mW/cm²?

A

720 mW/cm²

42
Q

What describes the interaction of sound waves with microscopic, stabilized gas bubbles in tissues?

A

Radiation force

43
Q

What is the pressure threshold for transient cavitation compared to stable cavitation?

A

10% higher

44
Q

What are the two techniques used to study bioeffects?

A
  • Mechanistic Approach
  • Empirical Approach
45
Q

What is a key uncertainty in the mechanistic approach to bioeffect research?

A

Uncertainty about assumptions

46
Q

What is a potential drawback of the empirical approach to bioeffects?

A

Species differences may alter results

47
Q

What is the bioeffect research claim that should be viewed with caution?

A

Direct clinical significance without in vivo validation

48
Q

What does MI stand for in the context of ultrasound?

A

Mechanical Index

The Mechanical Index is a calculated number related to the likelihood of harmful bioeffects from cavitation.

49
Q

What are the two sound wave characteristics related to the Mechanical Index?

A
  • Peak rarefaction pressure
  • Frequency
50
Q

What happens to cavitation and pressure when the Mechanical Index is higher?

A
  • More cavitation
  • More pressure
  • Lower frequency
51
Q

What happens to cavitation and pressure when the Mechanical Index is lower?

A
  • Less cavitation
  • Less pressure
  • Higher frequency
52
Q

Define epidemiology.

A

A branch of medicine associated with population studies and the prevalence of disease

It is empirical and often uses clinical surveys.

53
Q

What is a significant use of ultrasound in pregnant women?

A

Routine scanning during normal pregnancies.

54
Q

Why is it important to study ultrasound’s effects on fetuses?

A

Harmful effects, if present, have the potential to affect the fetus for life.

55
Q

What fetal evaluations are commonly assessed in epidemiologic studies involving ultrasound?

A
  • Fetal weight
  • Abdomen circumference
  • Head circumference
  • Femur length
  • Congenital abnormality
  • APGAR scores
  • Hearing
  • Infection
56
Q

True or False: Data indicates that ultrasound exposure is associated with adverse fetal outcomes.

A

False

Data indicates that ultrasound exposure is not associated with adverse fetal outcomes.

57
Q

What are limitations of epidemiologic studies mentioned in the text?

A
  • Studies are often retrograde
  • Ambiguities may exist in the data
  • Risk factors other than exposure to ultrasound may precipitate a bad outcome
58
Q

Fill in the blank: Antegrade studies are always _______.

A

[better]

59
Q

List some risk factors other than ultrasound exposure that may affect fetal outcomes.

A
  • Environmental factors
  • Poor nutrition
  • Smoking
  • Alcohol and drug abuse
60
Q

What are the best types of epidemiologic studies?

A

Prospective and Randomized studies

These studies are preferred for obtaining meaningful information and accounting for risk factors.

61
Q

What is an advantage of a prospective study?

A

A complete and accurate compilation of meaningful information is obtained

This helps in understanding patient outcomes more effectively.

62
Q

What do randomized studies do?

A

Create 2 groups of patients

This allows for better control of risk factors affecting fetal outcomes.

63
Q

What is a key conclusion regarding bioeffects from diagnostic ultrasound?

A

No confirmed harmful bioeffects have ever been reported

Future identification of bioeffects is possible, but not confirmed.

64
Q

What is the balance between benefits and risks in diagnostic ultrasound?

A

The benefits to the patient outweigh the risks

This supports the prudent use of diagnostic ultrasound.

65
Q

In what setting is it inappropriate to use diagnostic ultrasound?

A

Non-medical settings for entertainment

This use does not provide any medical benefit.

66
Q

What should patients be informed about when participating in research studies?

A

How the research study differs from standard diagnostic procedures

This is important when there is no direct medical benefit.

67
Q

What is the greatest risk associated with ultrasound equipment?

A

Electrical shock from a cracked transducer housing

Damaged transducers can also compromise image quality.

68
Q

What does ALARA stand for in the context of ultrasound?

A

As Low As Reasonably Achievable

This principle aims to minimize patient exposure.

69
Q

What does the term ‘prudent’ refer to in the context of ultrasound use?

A

Careful, judicious use

This emphasizes the need for valid medical justification.

70
Q

What should be done regarding the duration of ultrasound studies?

A

Do not prolong studies

This is part of the ALARA principle to minimize exposure.

71
Q

What is a common experience difference noted between diagnostic ultrasound and research?

A

Experience may differ due to longer research exams and greater exposure

This can affect the perceived safety and effectiveness of ultrasound procedures.

Physics (24 decks)

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