ultrasound physics ch 22-24
What form of resolution is evaluated by measuring the width of reflections arising from small, point targets? A. lateral resolution B. axial resolution C. temporal resolution D. elevational resolution
A. Lateral resolution
What is epidemiology the study of? A. large groups B. the prevalence of disease C. acoustic bioeffects on the fetus D. in vitro effects
B. Epidemiology is a division of medicine that is devoted study of the prevalence of diseases or pathology in a defined population
Which measure of intensity is related most closely to tissue heating? A. I(m) B. SATA C. SPPA D. SPTA E. SPTP
D. SPTA, spatial peak temporal average
Which two of the following devices convert ultrasound energy into heat? A. calorimeter B. thermocouple C. a hydrophone D. a Schlieren
A and B. The calorimeter and the thermocouple are two devices that use the principle of converting acoustic energy into thermal energy into thermal energy to estimate the energy in a sound beam
What information should be provided to a patient when undergoing a study for the purpose of research or training? A. the anticipated exposure conditions and how these compare to normal diagnostic procedures B. the duration of the exam C. the research study's goal D. bioeffects associated with the technique
A. A subject of a research or training exam should be informed of the exposure conditions and how they compare to those of a standard diagnostic ultrasound examination
The next step following the identification of an in vitro bioeffect is: A) Propose in vivo research to evaluate the clinical significance of the bioeffect B) Cease performing clinical studies that may induce bioeffects in vivo C) Ignore the results: it's only an in vitro observation D) Continue with in vitro research E) Obtain an informed consent regarding this report from all patients.
A. Further in vivo reasearch should be performed to understnad the impact of in vitro-identified bioeffects on living subjects
Some ultrasonic bioeffects studies are performed in vivo. What is the meaning of the term in vivo? A. observable in a living body B. observations based on an experiment C. discernible in a test tube D. estimated in a computer simulation
A. In vivo observations are made in a living body. For example, increased tissue temperatures in patients following exposure to ultrasound
What is the first action of sonographers upon entering a patient's room? A. introduce themselves to the patient B. plug in the ultrasound system C. check the patient's wristband D. wash their hands
A. Introduces themselves to the patient
Which of the following terms best describes the mechanistic investigation of bioeffects? A. cause-effect B. exposure-response C. cause-response D. exposure-cure
A. The mechanistic approach to the study of bioeffects is properly called cause and effect
All of the following may be used to evaluate Doppler systems except: A. tissue equivalent phantom B. moving belt phantom C. vibrating string phantom D. Doppler phantom
A. The tissue equivalent phantom is not suitable for evaluating Doppler systems because all the reflectors within it are stationary. Doppler evaluations require moving reflectors
A patient arrives at the ultrasound department. The patient does not have a wristband and is sedated. What should the sonographer do? A. call the nurse B. perform the study C. cancel the study D. reschedule the study
A. When sedated patients do not have proper identification, it is best to call the nurse
Which ultrasound modality is associated with the highest tissue temperature elevation? A. pulsed Doppler B. color flow Doppler C. gray scale imaging
A. pulsed Doppler
used to evaluate certain resolution and distances based on location and spacing of pins/rods
AIUM test object
Which of the following statement are true of a tissue equivalent phantom? A. it has the same propagation speed as that of soft tissue B. it attenuates ultrasound at a rate similar to soft tissue C. embedded in it are solid masses and cystic structures D. it is the device of choice for quality assurance studies
All the answers are true of a tissue equivalent phantom
What is the highest SPTA intensity of an unfocused ultrasound wave where there have been no observed bioeffects? A. 1 mW/cm(2) B. 100 mW/cm (2) C. 1000 mW/cm(2) D. 1 W/cm(2)
B. 100 mW/cm There have been no independently confirmed significant bioeffects in mammalian tissue exposure to unfocused ultrasound with intensities below 100 mW/cm
Which of the following epidemiologic studies is considered most likel to produce meaningful results? A. retrospective and prospective B. prospective and randomized C. retrospective and empirical D. prospecitve and mechanistic
B. A clinical trial that is both prospective and randomized is most likely to reach a valid and meaningful endpoint
What form of resolution is evaluated by visualizing closely spaced pins that are parallel to the sound beam's main axis? A. lateral resolution B. axial resolution C. temporal resolution D. elevational resolution
B. Axial resolution. Axial resolution is the smallest distance at which two pins positioned parallel to the sound beam are displayed as two distinct echoes
Which of the following terms describes the value that the actions of health care providers should benefit the patient? A. nonmaleficence B. beneficence C. justice D. autonomy
B. Beneficence
Which of the following is NOT a potential mechanism for production of bioeffects from ultrasound exposure to the body? A. temperature elevation B. fractionation C. cavitation D. vibration
B. Fractionation means "to separate a mixture into its ingredients" and has nothing to do with bioeffects
Which is generally true of diagnostic ultrasound? A. harmful bioeffects do not occur, and it is unnecessary to discuss them B. harmful bioeffects do no occur, but it is irresponsible to ignore the possibility that they may C. harmful bioeffects are often seen, but the benefit to patients still outweighs the risk D. only new technologies such as 3-D or intravascular ultrasound need to be evaluated for bioeffects
B. Harmful bioeffects do not occur, but it is irresponsible to ignore that they may
Guidelines to minimize the risk of health care workers to contract bloodborne infection have been developed. What are these guidelines called? A. OSHA guidelines B. standard precautions C. beneficence D. best practices
B. Standard precautions
Which of the following is related to cavitation bioeffects? A. TIS B. MI C. cavitation index D. pulsatility index
B. The MI, or mechanical index, is related to cavitation bioeffects. Higher values of MI are associated with increased likelihood of cavitation
Which of these terms best describes the empirical investigation of bioeffects? A. cause-effect B. exposure-response C. cause-response D.. exposure-cure
B. The empirical approach to the study of bioeffects searches for biologic response following an exposure to ultrasound
Which of the following statements regarding cavitation is true? A. it has never been observed in any biologic media B. stable cavitation relates to oscillating bubbles whiles transient relates to bursting bubbles C. it is a nonlethal bioeffect produced in animal experiments D. waves with peak pressures less than 100 MPa can never induce cavitation
B. This is the principal difference between the two forms of cavitation: stable cavitation means that the microscopic gas bubbles in the tissues are rhythmically swelling, whereas transient cavitation means the microscopic gas bubbles burst
Which component of an ultrasound system is most likely to expose a patient to danger? A. monitor B. transducer C. scan convertor D. pulser
B. Transducer
Which of the following ultrasound beams has a characterstic that is most likely to cause temperature elevation in soft tissue? A. strongly focused B. medium focused C. unfocused
C. An unfocused beam is most likely to cause temperature elevation in soft tissues. Termperature elevation with unfocused beams results from the broad area over which the beam spreads. With narrower, focused beams, the area insonated by the smaller beam is smaller and therefore heats a smaller mass of tissue
When can a patient revoke consent? A. prior to the start of the procedure B. four hours prior to the procedure C. at any time, even during the procedure D. never
C. At any time
Which of the following provides the basis for informed consent? A. notice B. a contract C. autonomy D. beneficence
C. Autonomy is the ability to act intentionally, with understanding
Research has indicated that cavitation _____. A. never occurs B. cannot occur with long pulses C. can be lethal to living things D. effects are purely theoretical
C. Cavitation resulting from ultrasound exposure is leathal to the fruit fly. Cavitation has the potential for significant and harmful bioeffects under specific circumstances
A comprehensive and scholarly review of bioeffects is performed by the AIUM for all of the following reasons except: A. ultrasound is a versatile technique B. ultrasound have proven widespread clinical utility C. ultrasound is considered highly toxic D. applications of ultrasound are growing considerably
C. Diagnostic ultrasound is not considered highly toxic or likely to expose patients to substantial risks
What is the study of the relationship between a worker and her environment called? A. pathology B. psychology C. ergonomics D. best practices
C. Ergonomics
Which of the following is not associated with the mechanistic approach? A. identifying cause-effect relationship B. proposing a specific means that could produce a bioeffect C. studying charts of patients who have been exposed to ultrasound D. analyzing the mechanism using theoretical methods E. reaching valid scientific conclusions
C. Evaluating patient charts is an element of the empirical study of bioeffects
Which of the following is the best and most appropriate action of a sonographer? A. hand washing before an exam B. hand washing after an exam C. hand washing before and after an exam D. using sterile technique during an exam
C. Hand washing before and after an exam
Which sound wave is least likely to create cavitation? A. 5 MHz, 2 MPa B. 2 MHz, 4 MPa C. 6 MHz, 2 MPa D. 2 MHz, 2 MPa
C. Low values of MI indicate low likelihood of cavitation.
What standard is best used in a quality assurance program? A. subjective B. expert C. objective D. legislative
C. Objective
The primary investigative technique of epidemiology is: A. computer modeling B. library research C. reviewing data from patients D. performing animal experiments
C. Reviewing data from patients
At what interval should quality assurance evaluations be performed? A. weekly B. daily C. routinely D. periodically
C. Routinely
Which statement allows us to conclude that diagnostic ultrasound does not injure tissues from temperature elevation? A. death resulting from an ultrasound exam has never been reported B. mechanistic data indicate that diagnostic ultrasound is safe C. conclusions from empirical data and mechanistic data are consistent; that is, diagnostic ultrasound is unlikely to cause thermally induced bioeffects D. patients do not complain of burning during ultrasound exams
C. Scientific conclusions are strongly justified when empirical and mechanistic investigations reach conclusions that are consistent
Which of these factors are relevant with regard to the thermal mechanism of bioeffects? A. rarefactional pressure and frequency B. compression pressure and frequency C. temperature and exposure time D. SPTA intensity and spatial pulse length
C. Temperature and exposure time. A combination of temperature and exposure time determine the likelihood of harmful bioeffects
Of the following choices, which is considered the most important for the sonographer with regard to bioeffects? A. pulse repetition frequency B. frequency C. duration of the study D. imaging mode
C. The exam duration is most significant because the sonographer directly controls it.
Which selection has the highest mechanical index? A. high frequency, high power B. high PRF, high intensity C. low frequency, high pressure D. high spatial pulse length, high PRF
C. The mechanical index is derived mathematically from the pressure in a sound beam and the sound's frequency. MI is highest with a high pressure sound beam of low frequency
The ________ measures beam intensity at specific locations, whereas a _______ measures the entire energy in a sound beam A. calorimeter, thermocouple B. Schlieren, thermocouple C. thermocouple, calorimeter D. thermometer, hydrometer
C. The thermocouple is a small electronic thermometer that measures the sound beam's energy at specific locations. The calorimeter absorbs all the beam's energy, converting it to heat. The calorimeter measures all the beam's energy
Certain studies of bioeffects are performed in vitro. What is the meaning of in vitro? A) visible in a living organism B) observations based on experiments C) discernible in a test tube D) perceptible in a living human being
C. an in vitro experiment is performed out of the body and in an artificial environment. The observations may be described as "in a test tube"
The upper limit for the SPTA intensity of a focused ultrasound wave where there have been no observed bioeffects is _____ A. 1 mW/cm B. 10 mW/cm C. 100 mW/cm D. 1 W/cm
D. 1 W/cm
What percentage of sonographers are thought to experience musculoskeletal pain related to work? A. 20 B. 40 C. 60 D. 80
D. 80%
Following the revocation of consent, when should a sonographer terminate the exam? A. immediately B. after all of the diagnostic information is obtained C. after the physician is notified D. at the first opportunity when it is safe
D. At the first safe opportunity. Even after revocation of consent, the procedure should only be terminated without exposing the patient to any additional risk or threat to safety
When studying bioeffects which research approach is more important? A. empirical B. mechanistic C. neither is important D. both are equally important
D. Both empirical and the mechanistic approaches are important. The strongest bioeffects conclusions are reached when the results of both approaches are in agreement
All of the following are characteristics of a tissue equivalent phantom except: A. speed of sound similar to that in soft tissue B. attenuation properties similar to that of soft tissue C. scattering characteristics similar to that of soft tissue D. density similar to that of soft tissue
D. Density similar to that of soft tissue. The density of the material within a tissue equivalent phantom is not important.
According to the AIUM, at what in situ tissue temperature is there danger to a fetus? A. 100 degrees C B. 98.6 degrees F C. 1 degree F over normal temperature D. 41 degrees C
D. Elevation of fetal tissue in excess of 41 degrees C is considered potentially harmful
Under which conditions is it permissible to perform a diagnostic ultrasound exam? A. when the patient will benefit B. when the patient has insurance C. when the exam is perfectly safe D. when the benefits outweigh the risks
D. It is proper to perform a diagnostic ultrasound exam when the benefit to the patient outweighs the risks that may be present
Which once of these terms is not associated with informed consent? A. describing reasonable alternatives B. the patient's acceptance C. evaluation of the patient's understanding D. justice
D. Justice is not associated with informed consent. It is a core value of medicine
Which of the following is least likely to make a patient experience a loss of dignity? A. advanced age B. sickness C. lack of privacy D. sedation
D. Sedation. Lack of dignity is not associated with sedation. Dignity is a state in which a person feels valued and worthy
Which of the following is an appropriate use of ultrasound in obstetrics? A. determine fetal gender B. viewing a fetus C. obtaining a picture of a fetus D. to provide medical benefit to the patient
D. The use of ultrasound is appropriate when providing medical benefit to the patient
Which component of an ultrasound system exposes a patient to greatest risk? A. the CRT B. the electric cord C. the pulser D. the transducer
D. Transducer
Epidemiologic studies of in utero exposure to ultrasound have included all of the following finding except: A. birth weight B. cancer C. structural abnormalities D. none of the above
D. none of the above
The study of the characteristics, attributes, and quantities of a substance that induces bioeffects is called ______.
Dosimetry
Which modes of Doppler may be assessed with a Doppler phantom? A. color flow Doppler B. pulsed Doppler C. power mode Doppler D. continuous wave Doppler E. all of the above
E. A Doppler phantom is a versatile device that evaluates all Doppler modes including pulsed, continuous wave, color flow, and power mode
Which of the following is not a limitation of epidemiological studies? A. medical charts are sometimes incomplete or inaccurate B. other factors, unrelated to the study's ultimate goal, must be accounted for C. when the bioeffect rate is small, numerous patients must be studied D. even when a bioeffect is identified the investigator is still unsure of the specific reason of its occurrence E. it does not provide greater understanding of the biologic significance of bioeffects
E. It does not provide greater understanding of the biologic significance of bioeffects
A bioeffects report claims that obstetrical scanning may be harmful to a particular group of patients. What should be the response of the medical community? A. perform the exams on all patients when the benefits are outweighed by the risks B. stop all diagnostic exams C. ignore the report D. halt all exams on this patient group E. perform exams on all patients when the benefits outweigh the risks
E. Perform exams on all patients when the benefits outweigh the risks
All of the following can reduce workplace injuries except: A. patient scheduling B. proper use of equipment C. educational programming D. patient positioning E. none of the above
E. none of the above. All of the choices listed can reduce the incidence of workplace injury
Veterans of a military operation suspect that they have been exposed to chemical warfare agents. The Veterans Administration Hospital surveyed these soldiers to identify the presence of symptoms and their prevalence. What form of medical investigation is this?
Empirical approach. Bioeffects are being investigated in a "exposure-response" context
True or False. A bioeffect identified through the mechanistic approach rather than the empirical approach is more likely to have clinical significance
False
True or False. A sonographer with advanced practitioner status can provide her impression of a study to the patient
False
True or False. There are no bioeffects associated with ultrasound
False
True or False. There are no bioeffects associated with ultrasound having characteristics typical of those in diagnostic medicine
False
True or False. Exposing an individual to ultrasound from a diagnostic imaging system is never appropriate when there is absolutely no clinical benefit to that individual
False.
True or False. The AIUM suggests that in vitro research confirming bioeffects is valuable and valid. Their results are significant and should be directly applied to the clinical arena
False. Although in vitro experiments results are extremely important, it is difficult to assess their direct clinical significance. Further studies should be performed before applying these conclusions clinically
True or False. In vitro studies are performed exclusively on living animals.
False. In vitro means literally "in glass"
True or False. Informed consent must always be obtained from the patient
False. Patients must have the capacity to provide consent. For example, when a patient has a legal guardian, the guardian can provide the consent to treat
True or False. Quality assurance evaluations of ultrasound systems should be performed weekly
False. Quality assurance evaluations must be performed routinely. The actual time between evaluations is determined by the pattern of use of the system
True or False. Quality assurance evaluations of ultrasound systems can only be performed by biomedical engineers or physical scientists
False. Quality assurance evaluations should be performed by the sonographers who use the systems
True or False. Bioeffects identified through in vitro research are not considered real.
False. The AIUM conclusively states that in vitro bioeffects must be considered real; however, their clincal importance is unknown
True or False. The biological effects of ultrasound are thought to be negligible and thus, few investigations have been performed on the subject
False. The biological effects of ultrasound are studied extensively by scientists throughout the world. Under specific circumstances, bioeffects have been confirmed and are the subject of many discussions, investigations, and publications
True or False. There are two forms of cavitation: inertial and normal
False. The correct answer is stable and normal
True or False. It is generally believed that the effects of ultrasound on biologic media are minimal
False. Ultrasonic bioeffects are substantial under certain conditions, including, but not limited to, therapeutic ultrasound and lithotripsy
True or False. A patient only communicates in a foreign language. It is acceptable to speak to a bilingual family member and obtain consent from the relative
False. Under these conditions, consent must be obtained from the patient, not from the family member
Which modality is associated with the lowest tissue temperature elevation? A. pulsed Doppler B. color flow Doppler C. gray scale imaging
Gray scale imaging
Name the two important mechanisms likely to produce bioeffects
Thermal and nonthermal (mechanical)
True or False. A patient only communicates in a foreign language. It is acceptable to have a bilingual family member serve as an interpreter, speak to the patient, and obtain consent from the patient
True
True or False. Cavitation describes that interaction between sound waves and small gas bubbles that exist in tissues
True
True or False. Focused sound beams are considered less likely to create bioeffects because the beams will strike fewer gas bubbles that could potentially cavitate
True
True or False. It is generally believed that the ultrasound bioeffects are minimal at intensity levels typical of those produced by diagnostic imaging equipment
True
True or False. Normal, transient, or inertial cavitation describes the bursting of microbubbles
True
True or False. One reason focused ultrasound beams with low intensities are less likely to cause bioeffects is that a focused beam is less efficient in heating a large mass of tissue to a critical temperature
True
True or False. The AIUM considers an ultrasound-induced biologic tissue temperature rise of less than 2 degrees Centigrade above normal body temperature as safe for clinical studies
True
True or False. The empirical approach to the study of bioeffects and ultrasonic safety surveys data involves finding a relationship between exposure and toxic effects
True
True or False. The intensity limit established for diagnostic ultrasound is higher for focused sound beams than for broad, unfocused beams
True. Broad unfocused sound beams cause greater tissue heating. The maximum intensity limit for these beams is therefore lower than that for focused beams
True or False. The transducer exposes a patient to the greatest risk
True. Since the transducer is in direct contact with the patient, it exposes the patient to the greatest risk
True or False. The mechanistic approach to the study of bioeffects and safety includes the identification of a theoretical construct that could produce an effect
True. The mechanistic approach is based on developing a theory as to how something happens. The mechanistic approach is considered "cause and effect"
True or False. Stable cavitation describes the rhythmic swelling and shrinking of gaseous nuclei
True. With stable cavitation, the microbubbles do not burst
True or False. Proper quality assurance programs require the assessment of every transducer used in the clinical laboratory
True: to establish a valid and rigorous quality assurance program, each component in clinical use must be evaluated
this type of resolution is measured by a slice thickness phantom
elevational
5
number of goals of a quality assurance program
4
number of requirements for a quality assurance program
Preventative Maintenance
perform this routinely
influenced by a person's beliefs or experiences
subjective standard
horizontal calibration
systems ability to place echoes in their correct position when the reflectors are perpendicular to the sound beam
flow phantom
type of Doppler phantom; interested in evaluating the accuracy of flow direction and volume velocities
phantoms
used to provide measurement and verification of beam characteristics and performance measurements
