Understanding Ultrasound Physics FINAL w/ Formulas

All of the following are true of sound waves except: (Ch.2, p.17, Q9) A. they are acoustic B. they are pressure waves C. they are transverse D. they move energy

C. Sound waves are longitudinal, not transverse

Which of the patterns in Fig 4.13 indicates a system with deep imaging depth? (Ch.4, p.65, Q5)

Choice B has the deepest imaging depth because the pulse repetition period is the longest.

Which patterns in Fig 4.13 indicates a system with a superficial imaging depth? (Ch.4, p.65, Q4)

Choice D has the shallowest imaging depth because the pulse repetition period is he shortest.

Which of the following best describes sound waves? (Ch.2, p.18, Q11) A. transverse, pressure waves B. transverse, longitudinal waves C. longitudinal, out-of-phase waves D. longitudinal, pressure waves

D

Which of the following best describes waves A and B? (Ch.2, p.16, Q1) A. in phase, will interfere constructively B. in phase, will interfere destructively C. out of phase, will interfere constructively D. out of phase, will interfere destructively

D

Which of the following best describes waves A and C? (Ch.2, p.16, Q3) A. in phase, will interfere constructively B. in phase, will interfere destructively C. out of phase, will interfere constructively D. out of phase, will interfere destructively

D

Which of the following terms does not belong with the others? (Ch.2, p.17, Q7) A. compression B. region of high density C. region of high pressure D. wide molecular spacing

D

T or F? The damping material in a transducer improves the system's lateral resolution. (Ch.8, p.126, Q8)

False. Damping does not affect lateral resolution.

T or F? The damping material in a transducer decreases bandwidth. (Ch.8, p.126, Q10)

False. Damping increases bandwidth.

T or F? The damping material in a transducer increases the sensitivity. (Ch.8, p.126, Q5)

False. Damping reduces sensitivity.

T or F? The damping material in a transducer increases the pulse length. (Ch.8, p.126, Q6)

False. Damping shortens pulse length.

T or F A very high Q factor transducer is used more often in diagnostic imaging transducers than a low Q factor? (Ch.8, p.126, Q3)

False. Imaging transducers are low-Q.

What is the relationship between ultrasound frequency and the attenuation coefficient in soft tissue? (Ch.6, p.89, Q8)

In soft tissue, the attenuation coefficient

When the number of cycles in a pulse increases while the frequency remains the same, the numerical value of the range resolution [increases, decreases, remains the same] (Ch.10, p.158, Q10)

Increases. With more cycles in a pulse, the pulse becomes longer. The numerical value of the range resolution increases.

Intensity formula (Ch.3, p.31)

Intensity (W/cm^2) =Power (W)/ area (cm^2)

Hours spent exercising and weight - inversely related, directly related, or unrelated? (Ch.1, p.4, Q6)

Inversely related. Weight decreases with an increase in exercise.

Spatial pulse length

N; Both; #cycles x wavelength (mm); mm, distance; 0.1-1.0 mm; SPL

Wavelength

N; Both; 1.54mm/us / frequency (MHz); mm, distance; 0.1-0.8 mm; λ

Speed

N; M; frequency (Hz) x wavelength (m); m/s; 1,500-1,600 m/s

Pulse duration

N; SS; #cycles/frequency, μs, time; 0.5-3.0 μs; PD

Period

N; SS; T=1/f; sec, us, time; 0.06-0.5 us, T

Frequency

N; SS; f=1/T; per sec, HZ; 2-15 MHz, f

A pulse of ultrasound is propagating in bone and center face with soft tissue at 90 degrees. A giant reflection is created. -From these facts alone, what can be said about the impedance of bone? -What can be said about the impedance of soft tissue? -What can be said about the differences between the impedances of bone and soft tissue? (Ch.6, p.96, Q3)

Nothing can be stated about the impedance of bone or soft tissue based on the information given. However, because a large reflection was created, the impedances of these two media must be dissimilar. Reflections with normal incidents are created based on the difference in the impedances, not the actual values of the impedances.

What type of incidence is there between Media 3 and 4? (Ch.6, p.106, Q7)

Oblique

______ is the time from the start of a pulse to the end of that pulse. (Ch.4, p.65, Q1)

Pulse duration

______ is the time from the start of a pulse to the end of the next pulse. (Ch.4, p.65, Q2)

Pulse repetition period

Pulse repetition frequency is the reciprocal of _______? (Ch.4, p.67, Q16)

Pulse repetition period.

Relationship between Rayleigh Scattering and frequency? (Ch.6, p.83)

Rayleigh Scattering is related to frequency^4

What happens at the boundary between Media 3 and 4? Why? (Ch.6, p.106, Q8)

Reflection may occur. If transmission does occur, the sound beam will refract because there are different propagation speeds and oblique incidence.

beam uniformity coefficient

SP/SA

Axial resolution

SPL (mm) / 2 wavelength (mm) x # cycles in pulse / 2 0.77 x # cycles in pulse / frequency (MHz)

Snell's Law

Sin (transmission angle)/Sin (incident angle) = Speed of Medium 2/ Speed of Medium 1

Infrasound

Sound waves with frequencies below 20 Hz.

SATA (Ch.5, p.73)

Spatial average, temporal average

A pair of 9 mm diameter probes are identical except for frequency, which is 3 MHz and 6 MHz, respectively. Which beam will have a shallower focus? (Ch.9, p.138, Q2)

The 3 MHz beam has a shallower focus. Focal depth increases with increasing frequency. The beam created by the 6 MHz probe has a deeper focus.

A pair of 9 mm diameter probes are identical except for frequency, which is 3 MHz and 6 MHz, respectively. Which beam will spread out more in the far field? (Ch.9, p.141, Q2)

The 3 MHz beam is more divergent. Beams are more compact as frequency increases. The 6 MHz beam will diverge less, whereas the 3 MHz beam will diverge more.

Two different transducers create pulses. Both transducers create sound with the frequency of four4 MHz. One transducer creates a pulse that comprises 6 cycles and the other, three cycles. Which transducer is more likely to create a more accurate image with respect to axial resolution? Which transducer has a lower numerical value of axial resolution? (Ch.0, p.150, Q11)

The 3-cycle pulse transducer is more likely to create an image with better axial resolution. Less ringing, or fewer cycles in a pulse, generally implies shorter pulses an improved axial resolution. The 3-cycle pulse has a lower numerical value of axial resolution. Lower numbers mean improved image accuracy.

Two different transducers create sound pulses. One transducer is labeled 5 mHz and the other, 3 MHz. Which transducer is more likely to create a more accurate image with respect to axial resolution? Which transducer probably has a lower numerical value of axial resolution? (Ch.10, p.150, Q10)

The 5MHz transducer is more likely to create an image with better axial resolution. higher frequency transducer creates a shorter pulse and thus has a lower numerical value of axial resolution. Lower numbers mean improved image quality.

What does the 3.5 dB/cm represent? (Ch.6, p.106, Q2)

The attenuation coefficient of the sound in the media

Spatial Peak Intensity (Isp) (Ch.5, p.70)

The beam's intensity at the location where it is maximum.

Which is better to use while examining a carotid artery, a 7.5 or 3.0 MHz transducer? (Ch.6, p.89, Q17)

The carotid artery is a superficial structure. A 7.5 MHz transducer is better because the higher frequency transducer produces the better image. We can use the higher frequency transducer in this example because the structure is superficial an attenuation is of little concern.

List these metric terms in INCREASING order: (Ch.1, p.8, Q7) A. mega B. micro C. milli D. hecto E. deca F. deci

The correct sequence of increasing order is as follows: B, C, F, E, D, A, or micro, milli, deci, deca, hecto, mega

What is the duty factor if the pulse duration is 1 microsecond, and the pulse repetition period is 1 ms? (Ch.4, p.67, Q19)

The duty factor is 0.001, or 10^-3. 10^-6 divided by 10^-3 10^-3, or 0.001.

What is the reciprocal of 20? (Ch.1, p.4, Q8)

The reciprocal of 20 is 1/20. 20 x 1/20= 1

T or F? The damping material in a transducer improves the system's longitudinal resolution. (Ch.8, p.126, Q9)

True.

True or False. Active element diameter and beam divergence are inversely related. (Ch.9, p.141, Q7)

True.

True or False. Active element diameter and near zone length are directly related. (Ch.9, p.138, Q6)

True.

True or False. Transducer frequency and beam divergence are inversely related. (Ch.9, p.141, Q6)

True.

True or false. Wavelength and near zone length are inversely related. (Ch.9, p.138, Q8)

True.

Snell's Law (Ch.6, p.102)

[Sin (transmission angle)/Sin (incident angle)] = [Speed of Medium 2/ Speed of Medium 1]

Name the three components of attenuation. (Ch.6, p.89, Q1)

absorption, reflection, and scattering.

angle of incidence

angle of incidence = angle of reflection

attenuation coefficient formula (Ch.6, p.85)

attenuation coefficient (dB/cm) = frequency (MHz) / 2

Total attenuation

attenuation coefficient (dB/cm) x distance (cm)

attenuation coefficient (Ch.6, p.85)

attenuation coefficient = 0.5 dB/cm/MHz

Temporal average intensity (Ita) (Ch.5, p.71)

averaging the intensity during the entire pulse repetition period- both the transmit and receive times.

axial resolution (mm) = ? (Ch.10, p.147)

axial resolution (mm) = spatial pulse length (mm) / 2 axial resolution (mm) = (wavelength (mm) x # cycles in pulse) / 2 In soft tissue: axial resolution (mm) = (0.77 x # cycles in pulse) / (frequency (MHz))

The ability to distinguish two structures lying close together front-to-back is called _______. (Ch.10, p.158, Q7)

axial, longitudinal, range, radial or depth resolution

Audible sound

between 20 Hz and 20 kHz

Frequency & PZT thickness

frequency (MHz) = sound's speed in PZT (mm/μs) / 2 x thickness (mm)

Attenuation coefficient

frequency(MHz)/2 or 0.5 dB/cm/MHz

If there are more cycles in a pulse, the numerical value of range resolution is [greater, lesser, same] (Ch.10, p.149, Q4)

greater

Attenuation in air is _______ attenuation in soft tissue. (Ch.6, p.89, Q5)

greater than

Attenuation in bone is _________ attenuation in soft tissue. (Ch.6, p.89, Q4)

greater than

Attenuation in lung tissue is [less than, greater than, the same as] attenuation in soft tissue. (Ch.6, p.89, Q3)

greater than

Ultrasound

greater than 20 kHz or 20,000 Hz

What is the duty factor if the pulse duration is 1 millisecond, and the pulse repetition period is 1 second? (Ch.4, p.67, Q20)

he duty factor is 0.001, or 0.1%, 0.001 divided by 1.0 = 0.001.

Impedance formula (Ch.6, p.88)

impedance (rayls) = density (kg/cm^3) x propagation speed (m/s)

Acoustic impedance = _______ x ______. (Ch.6, p.89, Q14)

impedance = density (kg/m^3) x propagation speed (m/s)

Incident intensity (Ch.6, p.99)

incident intensity (W / cm^2) = reflected intensity + transmitted intensity

incident intensity formula (Ch.6, p.92)

incident intensity = reflected intensity + transmitted intensity

Incident intensity

incident intensity = reflected intensity + transmitted intensity units: W/cm^2

Every 10 dB change means that the intensity will ____? (Ch.6, p.79, Q2)

increase ten times

As frequency decreases, depth of penetration ______ (Ch.6, p.89, Q10)

increases

As the path length increases, the attenuation of ultrasound in soft tissue _______. (Ch.6, p.89, Q2)

increases

If all factors remain unchanged, what happens to the duty factor (increases, decreases, remains the same) when the pulse repetition frequency increases? (Ch.4, p.62, Q1)

increases

If all factors remain unchanged, what happens to the duty factor (increases, decreases, remains the same) when the sonographer uses a new transducer with a longer pulse duration? (Ch.4, p.62, Q4)

increases

The frequency of a transducer does not change. If the diameter of the new piezoelectric crystal increases, what happens to the beam diameter in the near zone? (Ch.9, p.143, Q4)

increases

The frequency of a transducer does not change. If the diameter of the new piezoelectric crystal increases, what happens to the near zone length? (Ch.9, p.143, Q1)

increases

Pulse duration is [directly or inversely] related to bandwidth (Ch.8, p.121, Q4)

inversely

Q-factor is [directly or inversely] related to bandwidth (Ch.8, p.121, Q3)

inversely

Density and speed:

inversely related

As the path length increases, the attenuation of ultrasound in soft tissue _______. (Ch.6, p.89, Q13)

remains the same

The ability to distinguish between two structures lying close together ______. (Ch.10, p.158, Q6)

resolution

What is the ability to accurately distinguish two structures lying close together called? (Ch.10, p.149, Q1)

resolution

SAPA (Ch.5, p.73)

spatial average, pulse average

SATP (Ch.5, p.73)

spatial average, temporal peak

SPPA (Ch.5, p.73)

spatial peak, pulse average

SPTA (Ch.5, p.73)

spatial peak, temporal average

SPTP (Ch.5, p.73)

spatial peak, temporal peak

Pulse average intensity (Ipa) (Ch.5, p.71)

taking the average intensity during the pulse duration (transmit time).

Spatial average intensity (Isa) (Ch.5, p.70)

the average intensity across the beam's entire cross-sectional area.

Impedance is associated with ____. (Ch.6, p.89, Q12)

only the medium

Liver

1,560 m/s

Muscle

1,600 m/s

Tendon

1,700 m/s

Focal depth, diameter, and frequency

- focal depth (mm) = diameter (mm)^2 x frequency (MHz) / 6 - focal depth (mm) = diameter (mm)^2 / 4 x wavelength (mm)

A reduction in the intensity of a sound beam to one-half of its original value is _____ dB. (Ch.6, p.79, Q3)

-3 dB

A reduction in the intensity of a sound beam to one-quarter of its original value is _____ dB. (Ch.6, p.79, Q4)

-6 dB

Fat

1,450 m/s

Water

1,480 m/s

Soft tissue

1,540 m/s

Blood

1,560 m/s

Match the appropriate term to the unit (Ch.1, p.10) TERM: 1. time 2. length 3. cost 4. volume 5. area 6. test score 7. mass 8. temperature UNITS: A. 6 square miles B. -9 degrees C. 14 kilograms D. 83% E. 15m^3 F. 12 centimeters G. 4 minutes H. 86 cents

1. G 2. F 3. H 4. E 5. A 6. D 7. C 8. B

The "ten commandments" of Intensity Ch.5, p.74)

1. Intensities may be reported in various ways with respect to time and space. 2. The different measurements of intensities are important in the study of bio effects. SPTA is the most relevant intensity with respect to tissue heating. 3. The units for all intensities are watts/cm^2 4. Because peak measurements are larger than average measurements, SPTP intensity has the highest value, and SATA has the lowest value. 5. A number called the beam uniformity coefficient (also called SP/SA factor) Describe the spread of a beam in space. The SP/SA factor is unitless, with a value of 1 or greater. 6. The duty factor describes the relationship of beam intensities with time. It is a unitless number with a value between 0 and 1. 7. For continuous wave ultrasound , the beam is always "on" and the pulse average and temporal average intensities are the same. Thus, SPTA = SPPA and SATA = SAPA. 8. When pulse and continuous wave sound beams have the same SPTP intensities, the continuous wave beam has the higher SPTA intensity. When pulsed and continuous wave sound beams have the same SATP intensities, the continuous wave beam has the highest S ATA intensity. 9. Temporal considerations: · Temporal peak intensity () is maximum intensity and time · intensity is averaged over the most intense half cycle. · Pulse average intensity (is averaged only during the pulse duration ("on" time only). · Temporal average intensity () is average during the PRP (both the "on" and "off" times). 10. Spatial peak intensity () is the maximum in space while spatial average intensity () is averaged over the cross-sectional area of the beam.

Interaction

1. Sound back to transducer: specular (organized, diffuse/scattering (disorganized) 2. Sound in all directions: Rayleigh scattering (organized), scattering (disorganized)

sin divergence angle

1.85/ diameter (mm) x frequency(MHz) 1.2 x wavelength / diameter

Relationship between intensity reflection coefficient and intensity transmission coefficient? (Ch.6, p.94)

100% = intensity reflection coefficient (IRC) (%) + intensity transmission coefficient (ITC) (%)

Relationship between reflection coefficient and transmission coefficient (Ch.6, p.99)

100% = reflection coefficient + transmission coefficient

Sound is traveling from bone to soft tissue. The impedances of the media differ significantly, and 90% of the beam's intensity is reflected. What percentage of the intensity is transmitted? (Ch.6, p.98, Q1)

100% of the energy must be accounted for. If 90% is refracted, 10% must be transmitted.

Metals

2,000 - 7,000 m/s

Decibels and intensity

3 dB: double 10 dB: 10 x longer -3 dB: half -10 dB: 1/10 or one tenth

Bone

3,500 m/s

The impedance of medium one is 8 rayls. The propagation speed is 1450 m/s. The impedance of medium 2 is 6 rayls and the speed is 1.855 km/s. A sound beam strikes the boundary between the media and is both partially transmitted and reflected. The angle of the incident beam is 30 degrees. What is the reflection angle? (Ch.6, p.105, Q7)

30 degrees. The angle of reflection equals the angle of incidence.

Air

330 m/s

Sound is traveling in the medium and strikes a boundary with normal incidents. If 63% of the waves intensity is reflected back toward the transducer, what percentage is transmitted? (Ch.6, p.96, Q2)

37% of the intensity will be transmitted. Conservation of energy occurs at a boundary, and as a result, the sum of the reflected and transmitted intensities must equal 100%. 63% + 37% = 100%.

What is he lateral resolution at a depth of 8 cm? (Ch.10, p.157, Q1)

4.5 mm. At the end of the near zone, the beam diameter is 1/2 the transducer diameter.

Lung

500 m/s

What is the lateral resolution at a depth of 16 cm? (Ch.10, p.157, Q2)

9 mm. At a depth of twice the near zone, the beam is as wide as the transducer.

Angle of incidence

= angle of reflection

lateral resolution

= beam diameter (mm)

Which two of the patterns in Fig 4.13 identify an ultrasound system that cannot perform anatomic imaging? (Ch.4, p.65, Q6)

A and C. System A cannot perform anatomic imaging because it is continuous wave . Only pulsed sound creates imaging. Also, system C cannot perform imaging because it does not produce sound.

A pulse of ultrasound is propagating in soft tissue, such as liver. The pulse strikes a boundary with a different soft tissue at normal incidence. What portion of the intensity is reflected back toward the transducer? Why? (Ch.6, p.96, Q1)

A very small percentage of sound, typically less than 1%, is reflected at a boundary between two soft tissues. The impedance of two soft tissues are similar, and the difference in impedance directly determines the intensity reflection coefficient. Very little reflection occurs when the impedance have similar, but not identical, values.

Which of the following are considered acoustic parameters? (More than one answer may be correct.) (Ch.3, .46, Q29) A frequency B. density C. distance D. pressure E. period

A, E

A sound wave is created by a transducer, reflects off an object, and returns to the transducer. The go-return time is 130 µs. What is the maximum pulse repetition frequency? A. 7700 Hz B. 5000 kHz C. 10 cm D. 100 µs

A. 7700 Hz

Four waves have pulse repetition periods as listed below. Which of the following four waves has the lowest PRF? a) 8 s b) 80 us c) 8000 ns d) 800 ms (Ch.4, p.59, Q4)

A. 8 s. The pulse with the longest pulse duration will have the lowest pulse repetition frequency.

How much smaller is a hundred than a thousand? (Ch.1, p. 10, Q19) A. 1/10 B. 1/100 times C.1/ 1000 times D. 1/10000 times

A. A hundred is one-tenth of a thousand.

Which of the following best describes the line identified by the letter C? (Ch.3, p.42, Q8) A amplitude B. peak-to-peak amplitude C. frequency D. wavelength E. none of the above

A. Amplitude

What is the diameter of the sound beam at a depth of 8 cm? A. 6 mm B. 9 mm C. 12 mm D. 8 mm (Ch.9, p.133, Q2)

A. At the end of the near zone (which in this example is 8 cm), the beam diameter is one half the transducer diameter.

How is the age of a loaf of bread related to its freshness? (Ch.1, p.7, Q3) A. inversely B. directly C. unrelated

A. Inversely. As a loaf of bread ages, its freshness decreases.

Of the four waves whose frequencies are listed below, which has the shortest period? (Ch.3, p.26, Q9) A. 12 kHz B. 6,000 Hz C. 205 Hz D. 1 kHz

A. Of the 4 choices, A has the highest frequency and, thus, the shortest period.

For the transducer described in question 25, what is the Q-factor? A. 0.8 B. 3 MHz C. 5 MHz D. 1.5 E. 2 MHz (Ch.8, p.128, Q27)

A. Q-factor s resonant frequency divided by bandwidth, 5 MHz / 6 MHz. Bandwidth has no units.

A sound wave, with an intensity of 50 W/cm², strikes a boundary and is totally reflected. What is the reflected intensity? A. 50 w/cm^2 B. 25 w/cm^2 C. 0 w/cm^2 D. 100% E. 0 (Ch.6, p.94, Q2)

A. Since the wave is totally reflected, intensity is 50 w/cm^2.

At which of the following depths is the beam narrowing? A. 6 cm B. 8 cm C. 12 cm D. 10 cm E. 9 cm (Ch.9, p.134, Q7)

A. The beam narrows within the near zone. The only depth within the near zone is choice A.

What depth marks the beginning of the focal zone? A. 6 cm B. 8 cm C. 12 mm D. 8 mm (Ch.9, p.133, Q5)

A. The focal zone is the region around the focus. In this example, the focal zone begins at a depth 2 cm shallower than the focus.

All of the following correctly describe an imaging transducer except: A. high sensitivity B. low Q C. wide bandwidth D. damped (Ch.8, p.121, Q6)

A. Transducers have a LOW sensitivity.

A sonographer is using a 3 MHz transducer and changes to a 6 MHz transducer. The imaging depth remains unchanged. Would each of the following parameters increase, decrease, or remain the same? A. period B. frequency C. wavelength D. speed E. intensity (initial) F. PRF G. pulse repetition period (Ch.4, p.68, Q22)

A. decreases B. increases C. decreases D. remains the same E. remains the same F. remains the same G. remains the same

dB is a mathematical representation with a ____ scale. A. logarithmic and relative B. division and relative C. longitudinal and relative D. logarithmic and absolute (Ch.6, p.79, Q6)

A. logarithmic and relative

By changing the imaging depth, which of the following does the operator also change (more than 1 may be correct). A. pulse repetition frequency B. duty factor C. propagation speed D. pulse repetition period E. amplitude F. Spatial pulse length (Ch.4, p.67, Q17)

A. pulse repetition frequency B. duty factor D. pulse repetition period

A sonographer is using a 3 MHz transducer and increases the output power to visualize structures that are positioned deeper in the patient. No other controls are adjusted. Would each of the following parameters increase, decrease, or remain the same? A. period B. frequency C. wavelength D. speed E. power (initial) F. intensity (initial) G. pulse duration H. PRF I. duty factor J. spatial pulse length K. pulse repetition period (Ch.4, p.68, Q23)

A. remains the same B. remains the same C. remains the same D. remains the same E. increases F. increases G. remains the same H. remains the same I. remains the same J. remains the same K. remains the same

A sonographer adjusts the depth of view of an ultrasound scan from 8 cm to 16 cm. Would each of the following parameters increase, decrease, or remain the same? A. period B. frequency C. wavelength D. speed E. amplitude (initial) F. pulse duration G. PRF H. duty factor I. spatial pulse length J. pulse repetition period (Ch.4, p.68, Q21)

A. remains the same B. remains the same C. remains the same D. remains the same E. remains the same F. remains the same G. decreases H. decreases I. remains the same J. increases

For the transducer described in question 25, what is the main frequency? A. 5 MHz B. 8 MHz C. 3 MHz D. 6 MHz E. 2 MHz (Ch.8, p.128, Q26)

A. the resonant, main, or center frequency is 5 MHz.

If the media are soft tissue, what is an estimate of the ultrasound frequency? (Ch.6, p.106, Q3)

About 7 MHz; the attenuation coefficient multiplied by 2 approximates the frequency (3.5 x 2 = 7).

The effects of a medium on an ultrasound wave are called ________. (Ch.3, p.46, Q31)

Acoustic propagation properties

With A-mode, what is displayed on the y-axis? (Ch.11, p.163, Q5)

Amplitude of the reflected signal.

What processes occur as the ultrasound passes through the media? What are the units of this process? (Ch.6, p.106, Q9)

Attenuation (scattering, absorption, and reflection). Units: dB.

Two different transducers create pulses. One transducer is labeled 5MHz and the other, 3 MHz. The 3 MHz transducer creates a more accurate image with respect to axial resolution. Explain. (Ch.10, p.150, Q12)

Axial resolution is determined by pulse length. Shorter pulses have better axial resolution. In this question, the 3MHz transducer has the best axial resolution, which means the three MHC pulse must be shorter than the 5 MHz pulse. Since 3MHz sound has a longer wavelength than 5 MHz sound, the only way that the 3 MHz pulses shorter is if the 3 MHz transducer rings less. Thus, the 3MHz pulse has fewer cycles than the five MHz pulse.

Which of the lines above, A, B, or C, is most likely to be determined by the source and the medium? (Ch.3, p.43, Q12)

B

Which mode provides for real time, grey scale anatomic imaging? (Ch.11, p.163, Q4)

B-mode, or brightness mode.

The length of a pulse is 8 mm. What is the minimum distance between two reflectors, positioned one in front of the other, that still produces two echoes on our image? A. 8 mm B. 4 mm C. 16 mm D. 2 mm E. Cannot be determined (Ch.10, p.158, Q15)

B. 4 mm: This value is 1/2 the pulse length

How many milliliters are contained in a jar filled with 5 liters of fluid? (Ch.1, p.9, Q15) A. 5 B. 5000 C. 500 D. 0.005

B. 5000

What is the shape of a sound beam created by a tiny piece of PZT? A. hourglass shaped B. V-shaped C. round D. shaped like a tube (Ch.9, p.144, Q6)

B. A small piece of PZT creates a sound beam that is V-shaped. This wave is also called a diffraction pattern or a Huygens' wavelet.

How much bigger is a thousand than ten? (Ch.1, p.10, Q17) A. 10 times B. 100 times C. 1000 times D. 500 times

B. A thousand is 100 times bigger than ten.

Which of these waves is ultrasonic and most useful in diagnostic sonography? (Ch.3, p.25, Q5) A. 400 MHz B. 4 MHz C. 2 kHz D. 200,000 Hz

B. Although choices A, B, and D are all ultrasonic, only answer B falls within the typical range of frequencies used in diagnostic sonography.

Which of the following probes creates a beam with the least divergence? A. 4 mm diameter, 4 MHz B. 6 mm diameter, 8 MHz C. 4 mm diameter, 2 MHz D. 5 mm diameter, 8 MHz (Ch.9, p.141, Q3)

B. Divergence is minimized with large diameter, high frequency probes. The probe identified as choice B has the largest diameter in highest frequency. Therefore, it has the most compact, least divergent beam.

Which of the following probes creates a beam with the deepest focus? A. 4 mm diameter, 4 MHz B. 6 mm diameter, 8 MHz C. 6 mm diameter, 2 MHz D. 5 mm diameter, 8 MHz (Ch.9, p.138, Q3)

B. Longer focal lengths are associated with large diameter, high frequency probes. The probe identified as choice B has the largest diameter and highest frequency and, therefore, the deepest focus.

Which of the following locations is the most shallow? A. beginning of the far zone B. beginning of the focal zone C. focal depth D. beginning of the Fraunhofer zone (Ch.9, p.144, Q9)

B. Of these choices, the beginning of the focal zone is the most shallow

The maximum imaging depth (depth of view) during an ultrasound exam is 10 cm. The sonographer adjusts the imaging depth to 20 cm. What happens to pulse repetition frequency? A. it is unchanged B. it is halved C. it is doubled D. it is 20 times longer (Ch.7, p.112, Q5)

B. Pulse repetition frequency is inversely related to imaging depth. When imaging depth doubles, pulse repetition frequency is halved.

The imaging depth during an ultrasound exam is 10 cm. The sonographer adjusts the imaging depth to 5 cm. What happens to pulse repetition period? A. it is unchanged B. it is halved C. it is doubled D. it is 20 times longer (Ch.7, p.112, Q6)

B. Pulse repetition period is directly related to imaging depth. When imaging depth is halved, pulse repetition period is halved.

Which of the following describes line C? A. frequency B. pulse rep. period C. period D. pulse duration E. duty factor F. amplitude (Ch.4, p.66, Q10)

B. Pulse repetition period.

If intensity remains the same while the power is doubled, what has happened to the beam area? (Ch.3, p.44, Q19) A. quadrupled B. doubled C. halved D. unchanged

B. Recall that intensity equals power divided by area. If intensity remains unchanged, then whatever happens to power must also happen to area. In his case, power has doubled. Therefore, area must have doubled as well.

Which of the following terms does not belong with the others? A. low duty factor B. shallow imaging C. low PRF D. low pulse repetition period (Ch.4, p.62, Q7)

B. Shallow imaging does not belong. The other three choices are all associated with deep imaging.

A sound pulse travels in Medium 1 and strikes an interface with another tissue, Medium 2 at 30 degrees. The angle of transmission is 10 degrees. In which medium does sound travel slowest? A. Medium 1 B. Medium 2 C. cannot be determined (Ch.6, 104, Q3)

B. Sound travels slowest in medium two period when the angle of transmission is less than the angle of incidence, sound travels slower in this second medium.

Which of the following characteristics will create the fastest speed of sound? (Ch.3, p.43, Q16) A high density, high stiffness B. low density, high stiffness C. high density, low stiffness D. low density low stiffness

B. Speed is inversely proportional to density and directly proportional to stiffness.

At what depth is the focus? A. 6 cm B. 8 cm C. 1 cm D. 12 mm (Ch.9, p.133, Q4)

B. The focal depth is he same as the length of the near zone.

At what location is the sound beam diameter three times greater than the transducer diameter? A. at the end of the near zone B. at the depth equal to 4 focal lengths C. at the end of the far zone D. at the triple-diameter depth (Ch.9, p.144, Q5)

B. The only region where the beam diameter exceeds the transducer diameter is at depths exceeding two focal lengths.

A sound wave is created by a transducer, reflects off an object, and returns to the transducer. The go-return time is 26 µs. What is the depth of the reflector? A. 1 cm B. 2 cm C. 3 cm D. 4 cm (Ch.7, p.111, Q2)

B. The reflector depth is 2 cm. 2 cm x 13 µs/cm = 26 µs

How are the size of a tree and its age related? (Ch.1, p.7, Q1) A. Inversely B. directly C. unrelated

B. directly. Generally, as a tree ages, its size increases.

A sound wave is created by a transducer, reflects off an object, and returns to the transducer. The imaging depth is 10cm in soft tissue. What is the maximum pulse repetition frequency? A. 7700 B. 7.7 kHz C. 3500 Pa D. 7700 µs (Ch.7, p.112, Q7)

B. is the correct answer because the units are correct.

Which of the following terms does not belong with the others? A. orthogonal B. oblique C. normal B. perpendicular (Ch.6, p.96, Q5)

B. oblique means "other than 90 degrees." The other three terms all have a meaning of "equal to 90 degrees."

The effects of sound waves on tissue in the body are called _____. (Ch.3, p.45, Q27)

Bioeffects

The incidence between the sound wave and the boundary between Media 1 and 2 is normal. What happens at the boundary between Media 1 and 2? Why? (Ch.6, p.106, Q5)

Both reflection and transmission occur. There are normal incidence and different acoustic impedances.

What is the best estimate for the resolution at 4 cm? A. 1 cm B. 9 mm C. 5 mm D. 14 mm (Ch.10, p.157, Q3)

C.

What is the best estimate for the resolution at 7 cm? A. 1 cm B. 9 mm C. 5 mm D. 14 mm (Ch.10, p.157, Q4)

C.

A wave's intensity is 2 mW/cm^2. There is a change of +9 dB. What is the final intensity? A. 6 mW/cm^2 B. 2 mW/cm^2 C. 16 mW/cm^2 D. 16 µW/cm^2 (Ch.6, p.79, Q8)

C. 16 mW/cm^2

which of these four pulses with PRFs listed below has the shortest pulse repetition period? A. 12 kHz B. 6,000 Hz C. 20 kHz D. 1 kHz (Ch.4, p.59, Q3)

C. 20 kHz. Post repetition period is the reciprocal of pulse repetition frequency. This answer has the highest pulse repetition frequency and, thus, the shortest pulse repetition period.

How many kilometers are in 3000 meters? (Ch.1, p.9, Q11) A. 1/300 B. 1/3 C. 3 D. 300 E. 3000

C. 3. Kilo means thousand. Three kilometers equal 3,000 meters.

Four pulses have pulse repetition periods as listed below. Which of the following four waves has the highest pulse repetition frequency? A. 8 s B. 80 ms C. 5 ms D. 400 ks (Ch.4, p.59, Q2)

C. 5 ms. The pulse with the shortest pulse duration will have the highest pulse repetition frequency.

Which of these four values for pulse repetition frequency would have the longest pulse repetition period? A. 2 kHz B. 4,000 Hz C. 6 Hz D. 1 kHz (Ch.4, p.59, Q1)

C. 6 Hz. Pulse repetition period is the reciprocal of pulse repetition frequency. This choice has lowest pulse repetition frequency and, thus, the longest pulse repetition pulse repetition period.

A sound wave is created by a transducer, reflects off an object, and returns to the transducer. The maximum imaging depth is 7.7 cm. What is the pulse repetition frequency? A. 7700 Hz B. 5000 kHz C. 10000 Hz D. 100 µs (Ch.7, p.112, Q8)

C. 77000 / 7.7 = 10000 Hz

What is the diameter of the sound beam at a depth of 16 cm? A. 6 mm B. 9 mm C. 12 mm D. 8 mm (Ch.9, p.133, Q3)

C. At a depth equal to 2 near zone lengths, the beam diameter is the same as the diameter of the active element.

What is the best estimate of the diameter or width of the sound beam as it exists the transducer? A. 6 mm B. 9 mm C. 12 mm D. 8 mm (Ch.9, p.133, Q1)

C. At the beginning, the sound beam diameter is the same as the diameter of the active element.

Which types of waves will exhibit both constructive and destructive interference? (Ch.2, p.18, Q13) A. waves of different amplitude B. a pair of longitudinal waves C. waves of different frequency D. out-of-phase waves

C. Both constructive and destructive interference occurs with waves with different frequencies,

Which of the following probes creates a beam with the most divergence? A. small diameter, high frequency B. large diameter, high frequency C. small diameter, low frequency D. large diameter, low frequency (Ch.9, p.141, Q5)

C. Divergence is pronounced with small diameter, low frequency probes.

In soft tissue, a 3 cycle, 1 MHz pulse has a pulse length equal to 4.5 mm. What is the axial resolution? A. 3 mm B. 1 mm C. 2.25 mm D. 1.54 mm (Ch.10, p.149, Q8)

C. In this setting, the axial resolution is 2.25mm. Axial resolution is 1/2 of the spatial pulse length (4.5mm/2=2.25mm)

Which of the following describes line D? A. frequency B. pulse rep. period C. period D. pulse duration E. duty factor F. amplitude (Ch.4, p.66, Q11)

C. Period. If the units for line D are time, line D is a period.

The maximum imaging depth (depth of view) during an ultrasound exam is 10 cm. The sonographer adjusts the imaging depth to 20 cm. What happens to pulse repetition period? A. it is unchanged B. it is halved C. it is doubled D. it is 20 times longer (Ch.7, p.111, Q4)

C. Pulse repetition period is directly related to imaging depth. When imaging depth doubles, pulse repetition period doubles.

A sound pulse travels in Medium 1 and strikes an interface with another tissue, Medium 2 at 30 degrees. The angle of transmission is 10 degrees. In which medium is the impedance higher? A. Medium 1 B. Medium 2 C. cannot be determined (Ch.6, p.105, Q4)

C. Refraction of sound at a boundary is unrelated to the impedances of the media. Therefore, with the information provided, it cannot be determined which material has a greater impedance. Refraction is affected by the speed of sound in the media.

A sound wave strikes a boundary with normal incidence. The impedances of the two media are identical. What percentage of the sound wave is refracted? A. 100% B. 75% C. 0% D. 25% E. 90% (Ch.6, p.105, Q6)

C. Remember, refraction cannot occur with normal incidence.

Which of the following probes creates a beam with the shallowest focus? A. small diameter, high frequency B. large diameter, high frequency C. small diameter, low frequency D. large diameter, low frequency (Ch.9, p.138, Q5)

C. Shorter focal lengths are associated with small diameter, low frequency probes.

Which of the following probes creates a beam with the shallowest focus? A. 4 mm diameter, 4 MHz B. 6 mm diameter, 8 MHz C. 4 mm diameter, 2 MHz D. 5 mm diameter, 8 MHz (Ch.9, p.138, Q4)

C. Shorter focal lengths are associated with small diameter, low frequency probes. The probe identified as choice C has the smallest diameter and lowest frequency and, therefore, the shallowest focus.

Which of he following crystals will produce sound with the lowest frequency? A. thin and with a low speed B. thin and with a high speed C. thick and with a low speed D. thick and with a high speed (Ch.8, p.127, Q20)

C. Sound with the lowest frequency is produced by a thick active element in which sound travels slowly.

Which of the following characteristics will create the slowest speed of sound? (Ch.3, p.44, Q17) A high density, high stiffness B. low density, high stiffness C. high density, low stiffness D. low density low stiffness

C. Speed is inversely proportional to density and directly proportional to stiffness.

At which of the following terms does not belong? A. focus B. end of the near zone C. end of the Fraunhofer zone D. middle of the focal zone (Ch.9, p.134, Q10)

C. The end of Fraunhofer zone is the very end of the sound beam.

Which of the following locations is the deepest? A. end of the Fresnel zone B. end of the focal zone C. end of the Fraunhofer zone D. end of the near zone (Ch.9, p.144, Q8)

C. The end of the Fraunhofer zone identifies the deepest part of a sound beam.

The impedance of a transducer active element is 1,900,00 Rayls, and the impendence of the skin is 1,400,000 Rayls. What is an acceptable impedance for the matching layer? A. 1,200,000 Rayls B. 1,400,000 Rayls C. 1,726,000 Rayls D. 1,950,000 Rayls (Ch.8, p.127, Q19)

C. The impedance of the matching layer is between hat of the active element and the skin.

Which of the following waves has the longest period? (Ch.3, p.26, Q7) A. 2MHz B. 4000Hz C. 6 Hz D. 1 kHz

C. The wave with a frequency of 6 Hz has the longest period. Period and frequency have an inverse relationship. Thus, the wave with the lowest frequency has the longest period.

At which of the following depths is the beam most likely to have the same diameter as it has at a depth of 11cm? A. 1 cm B. 3 cm C. 5 cm D. 8 cm E. 14 cm (Ch.9, p.134, Q9)

C. Think of the beam as being symmetrical around the focus. Thus, the beam diameter will be similar when it is 3 cm shallower and 3 cm deeper than the focus.

Which of the following transducer has the poorest axial resolution? A. 1.7 MHz and 4 cycles/pulse B. 2.6 MHz and 3 cycles/pulse C. 1.7 MHz and 5 cycles/pulse D.2.6 MHz and 2 cycles/pulse (Ch.10, p.149, Q7)

C. This is the longest pulse. It has the lowest frequency and the most ringing (more cycles/pulse)

Which of the following describes line D? A. frequency B. pulse rep. period C. wavelength D. pulse duration E. duty factor F. amplitude (Ch.4, p.66, Q12)

C. Wavelength. If the units for line D are distance, line D is a wavelength. Both wavelength and period describe a single cycle.

What do waves transfer from one location to another? (Ch.2, p.17, Q5) A. matter B. molecules C. energy D. water

C. Waves carry energy from place to place

Which of the following is not an appropriate unit for volume? (Ch.1, p.7, Q5) A. cubic miles B. gallons C. cm D. cm^3 E. pint

C. cm. Volume is measured in units of length cubed. Centimetres is simply a measure of length.

Which of the following terms does not belong with the others? A. high duty factor B. shallow imaging C. low PRF D. short pulse repetition (Ch.4, p.62, Q6)

C. low PRF is associated with deep imaging. The other three choices are all associated with shallow imaging.

What is the best estimate for the resolution at 21 cm? A. 1 cm B. 9 mm C. 5 mm D. 14 mm (Ch.10, p.157, Q5)

D.

What s the duty factor if the pulse duration is 1 µs and the pulse repetition period is 1 ms? A. 100% B. 0.1 C. 0.01 D. 0.001 (CH.4, p.62, Q5)

D.

Which of the following waves is infrasonic? (Ch.3, p.25, Q3) A. 4 MHz B. 400 kHz C. 28 Hz D. 2 Hz

D. A wave with a frequency less than 20 Hz cannot be heard because its frequency is less than the lower limit of human hearing

A pulsed-wave transducer has a resonant frequency of 5 MHz. The lowest frequency in the pulse is 2 MHz and the highest is 8 MHz. What is the bandwidth? A. 5 MHz B. 8 MHz C. 3 MHz D. 6 MHz E. 2 MHz (Ch.8, p.128, Q25)

D. Bandwidth is the range of frequencies found in a pulse. In this case, 8 MHz - 2 MHZ = 6 MHz.

Which of the following explains why a sound beam created by a disc-shaped crystal is hourglass shaped? A. Bernoulli's Principle B. Sheffield's Law C. Ohm's Law D. Huygens' Principle (Ch.9, p.144, Q7)

D. Huygens' Principle

Which of the following describes line A? A. frequency B. pulse rep. period C. period D. pulse duration E. duty factor F. amplitude (Ch.4, p.66, Q7)

D. Pulse duration. If the units for line A are time, line A is a pulse duration.

A sound beam wave with an intensity of 50 W/cm^2 strikes a boundary and is totally reflected. What is the intensity reflection coefficient? A. 50 w/cm^2 B. 25 w/cm^2 C. 0 w/cm^2 D. 100% E. 0 (Ch.6, p.94, Q1)

D. Since the wave is totally reflected the intensity reflection coefficient is 100%.

Which of the following describes line A? A. frequency B. pulse rep. period C. period D. spatial pulse length E. duty factor F. amplitude (Ch.4, p.66, Q8)

D. Spatial pulse length. If the units for line A are distance, line A is a spatial pulse length. Both spatial pulse length and pulse duration describe a pulse.

Sound that is traveling in Jell-O passes through an interface at 90 degrees and continues to travel in whipped cream. The impedance of Jell-O and whipped cream are nearly identical. What percentage of the intensity is transmitted? A. 2% B. 25% C. 78% D. 99% (Ch.6, p.98, Q2)

D. The best choice is 99%. If the impedances of Jell-O and whipped cream are nearly identical, only a very small percentage of the sound beam's intensity will reflect. The remainder, of course, will transmit.

What is the period of the earth's rotation around the sun? (Ch.3, p.25, Q1) A. 1 day B. 1 hour C. 1 month D. 1 year

D. The earth completes one cycle around the sun in one year.

What depth marks the end of the focal zone? A. 6 cm B. 8 cm C. 10 mm D. 10 cm E. 8 mm (Ch.9, p.134, Q6)

D. The focal zone is the region around the focus. In this example, the focal zone ends at a depth 2 cm deeper than the focus.

What is the reciprocal of 1/8? (Ch.1, p.9, Q13) A. 80 B. 10 C. 1 D. 8 E. 72

D. The reciprocal of 1/8 is 8.

A sound wave is created by a transducer, reflects off an object, and returns to the transducer. The depth of the reflector is 10cm in soft tissue. What is the go-return time? A. 13 µs B. 1.3 µs C. 65 µs D. 130 µs (Ch.7, p.111, Q1)

D. Time of flight equals depth multiplied by 13 µs. 10 cm x 13 µs/cm = 130 µs.

Which of the following best describes the duty factor? A. A x B B. A/E C. D/E D. A/C E. E x F F. (A + B)/C (Ch.4, p.67, Q15)

D. To determine the duty factor, divide pulse duration by pulse repetition period. This is choice D.

A sound wave is created by a transducer, reflects off an object, and returns to the transducer. The go-return time is 26 µs. What is the total distance that the pulse traveled? A. 1 cm B. 2 cm C. 3 cm D. 4 cm (Ch.7, p.111, Q3)

D. Total distance traveled is twice the depth of the reflector.

Which of the following transducer has the best axial resolution? A. 1.7 MHz and 4 cycles/pulse B. 2.6 MHz and 3 cycles/pulse C. 1.7 MHz and 5 cycles/pulse D.2.6 MHz and 2 cycles/pulse (Ch.10, p.150, Q9)

D. tis is the shortest pulse. It has the highest frequency and the least ringing (fewest cycles/pulse)

Which of the following best describes the line identified by the letter D? (Ch.3, p.43, Q10) A amplitude B. peak-to-peak amplitude C. frequency D. wavelength E. none of the above

D. wavelength

True or False. We need one intensity to calculate decibels. (Ch.6, p.79, Q7)

False

What are the units of attenuation? (Ch.6, p.89, Q6)

Decibels (dB)

when the number of cycles in a pulse increases (more ringing) while the frequency remains the same, the image quality [improves, degrades, remains the same] (Ch.10, p.158, Q11)

Degrades. When the number of cycles increases, the spatial pulse length increases and the image quality degrades.

With A-mode, what is displayed on the x-axis? (Ch.11, p.163, Q2)

Depth of the reflector

With M-mode, what is displayed on the y-axis? (Ch.11, p.163, Q3)

Depth of the reflector

Imax (Im) (Ch.5, p.71)

Determining the average intensity during the most intense half-cycle.

Smoking and the likelihood of cardiovascular disease - inversely related, directly related, or unrelated? (Ch.1, p.4, Q2)

Directly related. Generally, individuals who smoke are more likely to have cardiovascular disease.

Axial resolution is measured with units of ______. (Ch.10, p.149, Q3

Distance (mm)

Which of the following probes creates a beam with the most divergence? A. 4 mm diameter, 4 MHz B. 6 mm diameter, 8 MHz C. 4 mm diameter, 2 MHz D. 5 mm diameter, 8 MHz (Ch.9, p.141, Q4)

Divergence is pronounced with small diameter, low frequency probes . The probe identified as choice C has the smallest diameter and lowest frequency. Therefore, it has the least compact, most divergent beam.

What is the wavelength of a wave with an unknown frequency traveling in soft tissue? (Ch.3, .45, Q25) A. 0.51 us B. 0.51 m/s C. 0.51 pascals D. 0.51 watts E. 0.51 mm

E is the only answer with units of distance. Choice A has units of time, B has units of speed, C has units of pressure, and D has units of power. Therefore, the only possible choice is E

Which of the following describes line F? A. frequency B. pulse rep. period C. period D. pulse duration E. peak-to-peak amplitude (Ch.4, p.67, Q14)

E. Peak-to-peak amplitude.

At which of the following depths is the beam widening? A. 2 cm B. 4 cm C. 6 cm D. 8 cm E. 9.375 cm (Ch.9, p.134, Q8)

E. The beam widens or diverges in the far zone. The only depth within the far zone is choice E.

Which of the following best describes the line identified by the letter A? (Ch.3, p.42, Q6) A. amplitude B.period C. frequency D wavelength E. peak-to-peak amplitude

E. peak-to-peak amplitude

Which of the following describes line B? A. frequency B. pulse rep. period C. period D. pulse duration E. duty factor F. amplitude (Ch.4, p.66, Q9)

F. Amplitude.

Which of the following describes line E? A. frequency B. pulse rep. period C. period D. pulse duration E. duty factor F. none of these (Ch.4, p.67, Q13)

F. None of the above. Line E represents only the listening time.

True or False. If the amplitude of a wave is increased to 3 times its original value, the intensity is increased by 6 times. (Ch.3, p.41, Q5)

False. Intensity is proportional to the amplitude squared. If we triple the amplitude, we increase the intensity by a factor of nine.

True or False. Propagation speed increases as frequency increases. (Ch.3, p.43, Q14)

False. Propagation speed is determined by the medium only. Frequency and speed are unrelated.

True or False. Propagation speed increases as frequency increases. (Ch.3, p.44, Q21)

False. Speed and frequency are unrelated.

T or F The diameter of the active element of a transducer helps to determine the frequency of the sound that the transducer creates. (Ch.8, p.127, Q14)

False. The diameter of the active element does not determine the frequency of the sound created by the transducer.

T or F? The acoustic impedance of the matching layer is approximately the same as he acoustic impedance of skin. (Ch.8, p.126, Q1)

False. The impedance of the matching layer is greater than the impedance of the skin.

True or False. Transducer frequency and near zone length are inversely related. (Ch.9, p.138, Q7)

False. They are directly related.

T or F Two piezoelectric crystals are made from the same material. The thicker crystal will make a pulsed transducer with a higher frequency. (Ch.8, p.127, Q16)

False. Thicker active elements create sound with lower frequency, not higher

True or False. Two waves can have identical pulse repetition frequencies, even if their pulse repetition periods are different. (Ch.4, p.59, Q5)

False. Two waves can never have identical PRFs if their pulse repetition periods are different.

T or F Two piezoelectric crystals are made from the same material. The thicker crystal will make a continuous transducer with a lower frequency. (Ch.8, p.127, Q17)

False. With a continuous wave transducer, active element thickness does not determine the sound beam's frequency.

T or F If the Frequency of the electrical excitation voltage of a pulsed wave transducer is 6 MHz, then the operating frequency of the transducer is 6 MHz (Ch.8, p.126, Q12)

False. With pulsed wave transducers, he frequency of sound is not determined by the electrical signal.

A sound pulse travels in Medium 1 and strikes an interface with another tissue, Medium 2 at 30 degrees. The angle of transmission is 10 degrees. From these facts alone, what can be said about: -the speed of sound in Medium 1? -the speed of sound in Medium 2? -the difference between the speeds of Media 1 and 2? (Ch.6, p.104, Q2)

Given only this information, we can say nothing about the speed of sound in medium one or medium two period however, because the beam refracted significantly (there was a 20 degree change in direction), the speeds of these two media are very different. Refraction depends on the difference in the speeds of sound in the two media, not the actual speeds.

[High, Low] frequency transducers generally have the best range resolution. (Ch.10, p.149, Q6)

High

[High, Low] frequency transducers have the best range resolution. (Ch.10, p.158, Q12)

High.

Conservation of energy

IRC (%) + ITC (%)

intensity reflection coefficient (IRC) (Ch.6, p.95)

IRC (%) = [(( Z 2 − Z 1 ) 2) / (( Z 1 + Z 2 ) 2)] x 100

Intensity Transmission Coefficient (ITC) (Ch.6, p.97)

ITC (%) = (transmitted intensity / incident intensity) x 100 ITC (%) = 1 - intensity Reflection coefficient

Which type of transducer has a greater bandwidth: continuous wave or imaging? (Ch.8, p.128, Q22)

Imaging transducers have a wider bandwidth than continuous wave transducers.

Which type of transducer has more backing material: therapeutic or imaging? (Ch.8, p.128, Q23)

Imaging transducers use more backing material than therapeutic transducers.

What property has units of rayls? How is it determined? (Ch.6, p.106, Q4)

Impedance is calculated, not measured. Impedance = density x speed.

For lateral resolution the mnemonic LATA stands for? (Ch.10, p.151)

Lateral Angular Transverse Azimuthal

Name the 3 synonyms for lateral resolution (Ch.10, p.158, Q14)

Lateral, angular, transverse, and azimuthal (mnemonic: LATA)

For axial resolution, what does LARRD stand for? (Ch.10, p.146)

Longitudinal Axial Range Radial Depth

Name the 4 synonyms for axial resolution (Ch.10, p.158, Q13)

Longitudinal, axial, range, radial, and depth (remember the mnemonic: LARRD)

What is the only display mode that provides information regarding reflector motion with respect to time? (Ch.11, p.163, Q1)

M-mode

Two media A and B have the same densities. The speed of sound in medium A is 10% higher than in medium B. Which medium has the higher acoustic impedance? (Ch.6, p.89, Q15)

Medium A's acoustic impedance is higher than medium B's. Recall that impedance equals speed multiplied by density. Since both media have identical densities and medium A's speed is 10% higher, then media A's impedance is 10% higher.

-10 dB means that the intensity is reduced to ______ of its original value. (Ch.6, p.79, Q5)

One-tenth

Pulse repetition frequency & imaging depth

PRF (Hz) = 77,000 cm/s / imaging depth (cm)

Pulse Repetition Frequency (PRF) (Ch.7, p.110)

PRF (Hz) = 77000 (cm/s) / imaging depth (cm)

PRF (Ch. 4, p.58)

PRF = 1/PRP

PRF x PRP = ? (Ch.4, p.58)

PRF x PRP = 1

pulse repetition period (Ch.7, p.109)

PRP (μs) = imaging depth (cm) x 13 (μs/cm)

Pulse repetition period & imaging depth

PRP (μs) = imaging depth (cm) x 13 μs/cm

PRP (Ch.4, p.58)

PRP = 1/PRF

Using a particular ultrasound system and transducer, which of the following cannot be changed by the operator? (Ch.3, p.41, Q3) A. Wavelength B. Frequency C. Intensity D. Propagation Speed E. Period F. Power G. Amplitude (initial)

Parameters are determined by: A. cannot B. cannot C. can D. cannot E. cannot F. can G. can

If the final intensity of a sound beam is more than the initial intensity, then the gain in dB is ____. (+ or -) (Ch.6, p.79, Q9)

Positive. The beam's intensity is increasing.

If the initial intensity of a sound beam is less than the final intensity, then the gain in dB is _____ (+ or -). (Ch.6, p.79, Q10)

Positive. The beam's intensity is increasing.

What are the duty factors of the 4 patterns that appear in Fig 4.13? HINT: To determine a duty factor, use a single pair of complete pulse duration and PRP times. (Ch.4, p.65, Q3

The duty factors are: -pattern A 100% -pattern B 33% -pattern C 0% -pattern D 50%

Which of the lines in the above graph represent a direct relationship? (Ch.1, p.4, Q10)

The green, blue, and purple lines represent a direct relationship. These three lines extend from lower left to upper right.

You are given 5 substances: backing material, PZT, matching layer, gel, and skin, whose impedances have been measured. Unfortunately, the labels identifying the impedance of each substance have fallen off these materials. There are five labels indicating impedances of 0.8 Mrayls, 1.9 Mrayls, 1.6 Mrayls, 2.0 Mrayls, and 1.0 Mrayls. If the impedance of the backing material is 1.9 Mrayls, what are the impedances soft tissue, matching layer, gel, and PZT? Why? (Ch.8, p.121, Q1)

The impedances of the substances are: -PZT - 2Mrayls -matching layer - 1.6 Mrayls -gel - 1.0 Mrayls -skin - 0.8 Mrayls. The impedance of the active element is similar to that of the backing material. To optimize the efficiency of sound energy transfer between the transducer and the body, impedances of the materials along the path from the PZT to the skin will decrease in order; the highest impedance will be that of the PZT, then the matching layer, then gel, and finally the skin.

What does the 100 mW/cm^2 represent? (Ch.6, p.106, Q1)

The incident intensity of the sound beam

A pair of 6 MHz probes are identical except for the active element diameters, which are 6 mm and 10 mm, respectively. Which beam will be more compact in the far field? (Ch.9, p.141, Q1)

The probe with a 10 mm active element has a less divergent beam. Larger diameter crystals produce beams that diverge less in the far field.

A pair of 6 MHz probes are identical except for the active element diameters, which are 6 mm and 10 mm, respectively. Which sound beam of which probe will have a shallower focus? (Ch.9, p.138, Q1)

The probe with a 6 mm active element has a shallower focus. Smaller diameter crystals produce beams with shallower foci.

The speed of a 5 MHz continuous wave is 1.8 km/sec. The wave is then pulsed with a duty factor of 0.5. Calculate the new propagation speed. (Ch.4, p.67, Q18)

The propagation speed for pulsed and continuous wave sound is the same; in this case, 1.8km/s. it depends only upon the medium through which the sound travels.

In an imaging transducer, what is the purpose of attaching the backing material to the PZT? (Ch.8, p.128, Q24)

The purpose of the backing material in imaging transducers is to improve image quality.

A pulse of ultrasound propagates in soft tissue, such as liver the pulse strikes a soft tissue - soft tissue interface with oblique incidents. Some of the sound energy is transmitted period to what extent is the transmitted beam refracted? (Ch.6, p.104, Q1).

The transmitted beam undergoes little to no refraction. A transmitted beam is refracted when incidence is oblique and the propagation speeds are different. Because the tissues on either side of the boundary are both "soft tissues," their speeds are nearly identical and little or no refraction occurs.

With B-mode, which axis is related to the strength of the reflection? (Ch.11, p.163, Q7)

The z-axis is related to reflection strength.

Which type of transducer has a greater Q- factor: therapeutic or imaging? (Ch.8, p.128, Q21)

Therapeutic transducers have a higher Q-factor than imaging transducers.

In M-mode, what is displayed on the x-axis? (Ch.11, p.163, Q6)

Time

Total attenuation formula (Ch.6, p.85)

Total Attenuation = Attenuation Coefficient (dB/cm) x distance (cm)

The incidence between the sound wave and the boundary between Media 2 and 3 is normal. What happens at the boundary between Media 2 and 3? Why? (Ch.6, p.106, Q6)

Transmission only. The impedances of the media are the same.

True or False? Acoustic variables allow us to determine which waves are sound waves and which are not. (Ch.2, p.18, Q15)

True

T or F The damping material in a transducer decreases the pulse duration (Ch.8, p.126, Q7)

True.

T or F The damping material in a transducer decreases the quality factor (Ch.8, p.126, Q11)

True.

T or F. Imaging transducers are usually of high rather than low bandwidth. (Ch.8, p.126, Q2)

True.

T or F. In a given medium, attenuation is unrelated to the speed of sound. (Ch.6, p.89, Q7)

True. Attenuation and propagation speed are unrelated.

T or F If the pulse repetition frequency of a transducer in increased, then the frequency of sound produced by transducer remains the same. (Ch.8, p.127, Q13)

True. Frequency and pulse repetition frequency are not related

True or False. Two waves can have identical PRFs, even if their frequencies are different. (Ch.4, p.59, Q7)

True. Frequency and pulse repetition frequency are unrelated.

T or F A pulse with a long pulse duration is likely to have a narrow bandwidth (Ch.8, p.126, Q4)

True. Longer events tend to have a narrow bandwidth. Shorter events tend to have wider bandwidth.

True or False. Two waves can have identical PRFs, even if their periods are different. (Ch.4, p.59, Q6)

True. Period and pulse repetition frequency are unrelated.

True or False. Propagation speed does not change as frequency increases. (Ch.3, p.44, Q23)

True. Propagation speed and frequency are unrelated

T or F. Shorter duration events (such as dampened pulses) are more likely to be wide bandwidth. (Ch.8, p.121, Q7)

True. Short duration events are likely to be wide bandwidth. Longer events are more likely to be narrow bandwidth.

T or F. The normal propagation speed in piezoelectric material is about 3-5 times greater than that of soft tissue. (Ch.8, p.127, Q18)

True. Sound travels much faster in PZT than soft tissue.

T or F If the Frequency of the electrical excitation voltage of a continuous wave transducer is 6 MHz, then the operating frequency of the transducer is 6 MHz (Ch.8, p.127, Q15)

True. The frequency of the electrical voltage and the frequency of the sound beam are identical with continuous wave transducers.

Duty factor % (Ch.4, p.61)

duty factor (%) = (pulse duration/pulse repetition period) x 100

True or False. PRF and pulse repetition period are determined only by the imaging depth. (Ch.4, p.59, Q8)

True. This is a very important concept.

What are the units of: (Ch.3, p.41, Q1) -wavelength -frequency -intensity -propagation speed -period -power

Units are as follows: -millimeters -hertz -watts/cm^2 -meters/second -second -watts

IQ and shoe size - inversely related, directly related, or unrelated? (Ch.1, p.4, Q4)

Unrelated. There is no relationship between shoe size and IQ.

What occurs when a PZT crystal's temperature is elevated above the Curie point? (Ch.8, p.121, Q8)

When PZT's temperature exceeds the Curie point, the PZT is depolarized. The crystal's piezoelectric properties are lost forever and the transducer is ruined.

Sound strikes a boundary between 2 media orthogonally. Although the media are very different, no reflection is created. How can this be? (Ch.6, p.96, Q4)

With normal incidents, reflections occur only when the impedances of the two media at the interface are different period two different media can have the same impedances , and when that happens, no reflection will be created.

Sound travels in a medium and orthogonally strikes a boundary with a different medium. Although sound waves traveling in the media have vastly different speeds, there is no refraction. How can this be? (Ch.6, p.105, Q5)

With normal incidents, refraction cannot occur. Refraction occurs only when there are different speeds in a bleak incident. Both conditions must be met. In this example, the incidence is normal - no refraction can occur.

Pulse repetition frequency

Y; SS; PRF=1/PRP; Hz, per sec; 1-10 kHZ; PRF

Pulse repetition period

Y; SS; PRP=1/PRF; ms; 0.1-1.0 ms; PRP

Amplitude

Y; SS; max value - min value/2; pascals, cm, g/cm^3, dB; 1-3 MPa

Intensity

Y; SS; power (w)/area (cm^2); W/cm^2, dB; 0.01-300 W/cm^2

Power

Y; SS; power oc amplitude^2; watts, dB; 4-90 mW

Duty factor

Y; SS; pulse duration/pulse rep. period x 100; no units; 0.2-0.5%; DF

If all factors remain unchanged, what happens to the duty factor (increases, decreases, remains the same) when the pulse repetition period increases? (Ch.4, p.62, Q3)

decreases

If all other factors remain unchanged, what happens to the duty factor (increases, decreases, remains the same) when imaging depth increases? (Ch.4, p.62, Q2)

decreases

The frequency of a transducer does not change. If the diameter of the new piezoelectric crystal increases, what happens to the beam diameter in the far zone? (Ch.9, p.143, Q2)

decreases

If a new pulsed transducer has many more cycles in its pulse, the image accuracy (improves, degrades, remains the same) (Ch.10, p.149, Q5)

degrades

Impedance

density (kgm^3) x prop. speed (m/s) units: rayls

Range equation

depth (mm) = 1.54 mm/μs x go-return time (μs) / 2

Depth of reflector (Ch.7, p.108)

depth (mm) = [1.54 (mm/μsec) x go-return time (μs)] / 2

Pulse length is [directly or inversely] related to pulse duration (Ch.8, p.121, Q2)

directly

Stiffness and speed:

directly related

Axial resolution and lateral resolution are both measured with units of _____. (Ch.10, p.158, Q9)

distance (mm)

What are the units of the half-value layer thickness? (Ch.6, p.89, Q9)

distance: cm

Every 3 dB change means that the intensity will ____? (Ch.6, p.79, Q1)

double

lateral resolution (mm) = ? (Ch.10, p.152)

lateral resolution (mm) = beam diameter (mm)

The ability to distinguish two structures lying close together side by side is called _______. (Ch.10, p.158, Q8)

lateral, angular, transverse or azimuthal resolution.

The sensitivity of transducers that create short duration pulses is likely to be [greater than, less than, or equal to] that of transducers that create long pulses. (Ch.8, p.121, Q5)

less than

The ability to distinguish two structures lying close together front-to-back or parallel to the sound beam is called ____________. (Ch.10, p.149, Q2)

longitudinal, axial, range, radial, or depth resolution

Ispta (Ch.5, p.73)

measured at the location where intensity is maximum and averaged over all time, both the transmit and receive times.

Isptp (Ch.5, p.72)

measured at the location where intensity is maximum, and at the instant in time when the most powerful part of the pulse passes.

Isppa (Ch.5, p.73)

measured at the location where intensity is maximum, averaged over the transmit time (pulse duration).

Isata (Ch.5, p.73)

measured over the entire cross-sectional area of the sound beam, and over all time.

Temporal peak intensity (Itp) (Ch.5, p.71)

measuring the intensity of the beam at the instant in time of its maximal value.

The frequency of a transducer does not change. If the diameter of the new piezoelectric crystal increases, what happens to the wavelength? (Ch.9, p.143, Q3)

no change

Relationship between period and frequency (Ch.3, p.23)

period x frequency = 1

Pulse Duration formulas. (Ch.4, p.50)

pulse duration (µs) = # cycles x period (µs) pulse duration (µs) = (#cycles)/(frequency (MHz))

Impedance is important in ____ at boundaries. (Ch.6, p.89, Q16)

reflections

As the length increases, the half boundary layer ______. (Ch.6, p.89, Q11)

remains the same

Intensity transmission coefficient

transmitted intensity/incident intensity x 100

Half-value layer

typical values: 0.25-1.0cm

wavelength formula (Ch.3, p.35)

wavelength(mm)=speed(mm/microseconds)/ frequency(MHz)