Physics | Quiz #2 Review Txtbk ?'s
Page 59 #’s 3 & 4
3. 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
Answer: C. 20 kHz
↳ Pulse repetition period is the reciprocal of pulse repetition
frequency. This answer has
the highest pulse repetition frequency &, thus, the shortest pulse repetition period
4. Four waves have pulse repetition periods as listed below.
Which of the following four waves has the lowest pulse repetition frequency?
A. 8s
B. 80 �s
C. 8000 ns
D. 800 ms
Answer: A. 8s
↳ The pulse with the longest pulse duration will have the lowest pulse
repetition frequency
Page 62 #’s 5 - 7
5. What is the duty factor if the pulse duration is 1 �s & the pulse repetition period is 1 ms?
A. 100%
B. 0.1
C. 0.01
D. 0.001
Answer: D) 0.001
6. 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 period
Answer: C. low PRF
↳ is associated w/ deep imaging. The other 3 choices are all associated w/ shallow
imaging
7. Which of the following terms does not belong with the others?
A) low duty factor
B) shallow imaging
C) low PRF
D) long pulse repetition period [PRP]
Answer: B) shallow imaging
↳ does not belong. The other 3 choices are all associated w/ deep imaging
Page 65 #’s 3 - 6
3. 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 & PRP times]
Answer: the duty factors are as follows:
✧ pattern A ↬ 100%
✧ pattern B ↬ 33%
✧ pattern C ↬ 0%
✧ pattern D ↬ 50%
4. Which of the patterns in Fig. 4.13 indicates a system with a superficial imaging depth?
Answer: D ↬ has the shallowest imaging depth because the pulse repetition period
is the shortes
5. Which of the patterns in Fig. 4.13 indicates a system with a deep imaging depth?
Answer: B ↬ has the deepest imaging depth because the pulse repetition period is
the longest
6. Which 2 of the patterns in Fig. 4.13 identify an US system that cannot perform anatomic imaging?
Answer: A & C
↳ System A cannot perform anatomic imaging because it is a continuous
wave
✓ Only pulsed sound creates imaging
↳ Also, System C cannot perform imaging because it does not produce sound
Page 66 #’s 7 - 12
Fig. 4.14 ↬ Use these waves to answer the following 9 questions
7. Which of the following describes line A?
A. Frequency
B. Pulse repetition period
C. Period
D. Pulse duration
E. Duty factor
F. Amplitude
Answer: D. Pulse duration
↳ If the units for line A are time - line A is a pulse duration
8. Which of the following describes line A?
A. Frequency
B.
C.
D.
E.
F.
Pulse repetition period
Period
Spatial pulse length
Duty factor
Amplitude
Answer: D. Spatial pulse length [SPL]
↳ If the units for line A are distance - line A is a spatial pulse
length
✓ Both spatial pulse length & pulse duration describe a pulse
9. Which of the following describes line B?
A. Frequency
B. Pulse repetition period
C. Period
D. Pulse duration
E. Duty factor
F. Amplitude
Answer: F. amplitude
10. Which of the following describes line C?
A. Frequency
B. Pulse repetition period
C. Period
D. Pulse duration
E. Duty factor
F. Amplitude
Answer: B. pulse repetition period
11. Which of the following describes line D?
A. Frequency
B. Pulse repetition period
C. Period
D. Pulse duration
E. Duty factor
F. Amplitude
Answer: C. period
↳ If the units for line D are time - line D is a period
12. Which of the following describes line D?
A. Frequency
B. Pulse repetition period
C. Wavelength
D. Pulse duration
E. Duty factor
F. Amplitude
Answer: C. wavelength
↳ If the units for line D are distance - line D is a wavelength
✓ Both wavelength & period describe a single cycle
--------------------------------------------13. Which of the following describes line E?
A. Frequency
B. Pulse repetition period
C. Period
D. Pulse duration
E. Duty factor
F. None of the above
Answer: F. None of the above
↳ Line E represents only the listening time
14. Which of the following describes line F?
A. Frequency
B. Pulse repetition period
C. Period
D. Pulse duration
E. Peak-to-peak amplitude
Answer: E. peak-to-peak amplitude
15. Which of the following best describes the duty factor?
A.
B.
C.
D.
E.
F.
AxB
A/E
D/E
A/C
ExF
[A + B]/C
Answer: D.
↳ To determine the DF
↬
PD ÷ PRP
↬
This is choice D
Pages 451 - 460 #’s 139 - `183
139. What are the units of pulse duration?
A. units of frequency [Hz, etc.]
B. msec only
C. units of time [sec, years, etc.]
D. units of distance [feet, etc.]
Answer: C. The pulse duration is the actual time that a transducer is creating one pulse
↳ Typically range of PD found in diagnostic imaging equipment: 0.3 - 2 �sec
*** Valid to report PD in any unit of time
140. What determines the pulse duration?
A. the source of the wave
B. the medium in which the pulse travels
C. both A & B
D. neither A nor B
Answer: A. The pulse duration is the actual time that a transducer is creating one pulse
↳ it’s determined by the US system
|
PD does not include the
listening time!
141. True or False? The pulse duration of an ultrasound & transducer system does not change
significantly as long as the system components remain unchanged
Answer: True
⤖The pulse duration is the timespan that a pulse exists
↳ It’s determined by the US system & the transducer
✓ Generally, it remains constant for a particular transducer
142. The pulse duration is expressed in the same units as the ___.
A. period
B. PRF
C. wavelength
D. density
Answer: A.
↳ The pulse duration & the period are measured in units of time [sec, min
or hr]
✓ PRF = units of hertz | wavelength = units of distance | density = units of mass per volume
143. Sonographers can adjust PD of an acoustic pulse since it depends on pulse's propagation speed
Answer: False
↳ A sonographer cannot change the pulse duration
✓ It’s a fixed feature of the transducer & US system
*** It does not depend upon propagation speed
144. Sonographers can adjust PD of an acoustic pulse since it depends upon the max imaging depth
Answer: False
↳ A sonographer cannot change the pulse duration
✓ It has a constant value & is not dependent on imaging depth
145. Sonographers cannot change the duration of a sound pulse unless the transducers are switched
Answer: True
↳ The PD depends upon the interaction of the pulser electronics of the
machine & transducer
✓ The pulse duration may change when the sonographer changes transducers
146. The PD cannot be changed under any circumstances or by any action of the sonographer
Answer: False
↳ Sonographers can alter PD by using a different imaging
transducer or US system
147. What is the pulse duration equal to?
A. frequency multiplied by period
B. period multiplied by wavelength
C. the number of cycles in the pulse divided by the wavelength
D. period multiplied by the number of cycles in a pulse
Answer: D.
↳ The pulse duration is the total time that the transducer is producing
a pulse
✓ The PD = time to make a single cycle [period] multiplied by # of cycles that make up pulse
*** Example: If there are 6 cycles in a pulse & each period is 0.2 �s --- the PD is 6 x 0.2 = 1.2 �s
148. What happens to the PD when a sonographer decreases the max imaging depth in an US scan?
A. increase
B. decrease
C. remains the same
D. cannot be determined
Answer: C.
↳
The time a transducer is “pulsing” doesn’t change w/
alterations in depth of view
149. The spatial pulse length describes certain characteristics of an US pulse. What are its units?
A. time
B. hertz
C. meters
D. none; it is unitless
Answer: C.
⤖Spatial pulse length is the distance that a pulse occupies in space
↳ it’s length is measured from the beginning to the end of the pulse
✓ it can be reported in any unit of distance
150. In diagnostic imaging, what determines the spatial pulse length?
A. the ultrasound system
B. the medium through which the pulse travels
C. both A and B
D. neither A nor B
Answer: C.
⤖The spatial pulse length is the distance or length of a pulse
↳ it depends upon the wavelength of each cycle in the pulse
✓ wavelength depends upon both the sound source & the medium through which it travels
*** the length of the entire pulse also depends upon both the source & the medium
151. Which of the following best describes the spatial pulse length?
A. frequency multiplied by wavelength
B. PRF multiplied by wavelength
C. wavelength multiplied by the number of cycles in the pulse
D. duty factor multiplied by the wavelength
Answer: C.
↳
the total L of a pulse = the L of each cycle in the pulse times the #
of cycles in the pulse
✓ Imagine the pulse as a train made up of a number of boxcars:
*** train’s L [SPL] = L of each car [wavelength] x # of cars in the train [# of cycles in the
pulse]
152. 2 transducers send US pulses into soft tissue. 1 transducer emits sound w/ a 4 MHz frequency &
the other produces sound @ a 6 MHz frequency. Each pulse has 4 cycles. Which has the greater SPL?
A. the 6 MHz pulse
B. the 4 MHz pulse
C. they are the same
D. cannot be determined
Answer: B. lower frequencies have longer wavelengths
↳ both pulses have same # of cycles ⤖pulse w/ longer wavelength per 1 cycle = ⇈ overall L
✓ in a given medium, waves with lower frequencies have longer wavelengths
*** 4 MHz wave has longer wavelength than 6 MHz wave ⤖longer SPL as well
153. Using a specific transducer, what happens to SPL as sonographers
⇈ maximum imaging depth?
A.
B.
C.
D.
increases
decreases
remains the same
cannot be determined
Answer: C.
⤖SPL is determined by # of cycles in pulse & wavelength of each cycle
↳ with the same system --- these factors are unchanged & the SPL remains
the same
154. True or False? While imaging soft tissue, SPL � change given components of US system = same
Answer: True
↳
overall length of a pulse is = to the wavelength multiplied by the #
of cycles in the pulse
✓ using a particular US system & transducer - the pulse length cannot change
155. On what does the PRP [pulse repetition period] depend?
A. the source of the sound wave
B. the medium through which the pulse travels
C. both A & B
D. neither A nor B
Answer: A. similar to the PRF, the PRP depends only on the US system
↳
PRP = time from start of 1 pulse to start of next pulse & includes
the PD & receiving time
✓ when sonographer adjusts the depth of view - the PRP is altered
*** listening time ↬ lengthened w/ deeper imaging & shortened w/ shallower
imaging
156. Sonographers adjust max imaging depth of US system. Which of the following also changes?
[more than one may be correct]
A. PRP [pulse repetition period]
B. wavelength
C. PRF [pulse repetition frequency]
D. frequency
Answer: A. & C.
↳
as imaging depth is altered ↬ the PRF & PRP change
✓ wavelength & frequency remain constant ↬ describe attributes of single cycle within pulse
*** wavelength & frequency = not affected by alterations in imaging depth
157. Which of the following correctly describes PRP?
A. the product of wavelength & propagation speed
B. the reciprocal of the frequency
C. the sum of the pulses on time & the listening off time
D. the time that the transducer is pulsing
Answer: C.
↳
PRP is the actual time form the start of one pulse to the start of the next
pulse
✓ PRP = time that transducer is pulsing [PD] + time that US system is listening for reflected echoes
158. What happens to the PRP if the sonographer decreases the maximum imaging depth achieved in
an ultrasound scan?
A. increases
B. decreases
C. remains the same
D. cannot be determined
Answer: B.
↳
➷
as maximum imaging depth [depth of view] ⇊
interval of time during which US machine listens for returning echoes = diminished
✓ as a result of this shorter listening time ⤍the PRP is shortened
*** Simplified: PRP & depth of view = directly related
Two US systems, 1 producing sound w/ frequency of 3 MHz & the other @ 6 MHz, are used to image
a pt. The max imaging depth of both exams is 8 cm. Are the following 4 statements true or false?
159. The period of the 3 MHz sound is greater than the period of the 6 MHz sound
Answer: True
↳
the period of a wave = the time that is required to complete 1 single
cycle
✓ a sound signal’s period & frequency = reciprocals | lower the frequency ⤍higher the period
*** the 3 MHz wave has a period twice as long as the 6 MHz wave
160. The wavelength of the 3 MHz ultrasound is greater than the 6 MHz sound
Answer: True
⤍ wavelength = the distance that a single cycle of a pulse occupies in space
↳ traveling through given medium: cycles from waves w/ ⇊ frequencies =
longer wavelengths
✓ cycles from a 3 MHz wave = longer wavelengths than those from a 6 MHz wave
161. The pulses produced by both systems travel at the same speed in the patient
Answer: True
↳
all sound waves travel in the same medium @ identical speeds
✓ frequency & speed = unrelated
162. The PRF of the 6 MHz transducer is greater than the PRF of the 3 MHz transducer
Answer: False
↳
the PRF is derived from the maximum imaging depth [established by
sonographer]
✓ the PRF changes only when the imaging depth changes
*** since the depth of view for both systems are the same ⤍ the PRFs are also the same
The maximum imaging depth during an exam is unchanged. a new transducer w/ longer PD is used.
Are the next 4 statements true or false?
163. The pulse repetition period is increased
Answer: False
↳
PRP is determined by the depth of view
✓ the maximum depth is unchanged ⤍ so the PRP is also unchanged
164. The pulse repetition frequency is increased
Answer: False
↳
PRF & PRP = reciprocals
✓ if the PRP = unchanged ⤍ then the PRF must also remain unchanged
165. The duty factor is increased
Answer: True
↳
Duty cycle is calculated by dividing the PD ÷ the PRP
✓ the PRP = unchanged
*** by changing to a transducer w/ a longer PD while PRP stays constant ⤏ DF ⇪
166. The frequency is increased
Answer: False
↳ carefully read the ? info ⤏note: � stated regarding frequency of sound emitted by
transducer
✓ conclusion: � can be concluded regarding frequency
167. What are the units of PRF [pulse repetition frequency] ?
Answer: B. 1/seconds
⤏ PRF: the # of pulses produced by US system in 1 second
↳ PRF has same units as frequency ⤏hertz _ Hz _ per second
168. The PRF of US produced by a transducer typical of diagnostic imaging systems
a. can be changed by the sonographer
b. depends on the medium through which the sound travels
c. is unchanged as long as the same ultrasound system is used
d. has nothing to do with clinical imaging
Answer: A. can be changed by the sonographer
↳ PRF & maximum imaging depth achieved during an exam = inversely
related
✓ Due to transducer needing to wait longer for echoes to return from deeper depths
*** if ⇈ maximum imaging depth ⤏ PRF must
⇊
[alter PRF if adjusting max imaging depth]
169. In diagnostic imaging, what establishes the PRF?
a. the source of the sound
b. the medium through which the sound travels
c. both a & b
d. neither a nor b
Answer: A. source of the sound
↬ sole determinant of PRF = source of acoustic
wave ⤏US system
↳ medium through which sound travels = doesn’t directly affect the PRF
170. When sonographers increase the max imaging depth during an exam, what happens to the PRF?
a. PRF increases
b. PRF decreases
c. remains unchanged
Answer: B. PRF decreases
related
⤳[* as imaging depth ⇈*]
| imaging depth & PRF = inversely
↳
when depth of view
⇈
⤏ system waits & listens a longer time for reflections
✓ this reduces system’s ability to send out as many pulses per second
171. True or False ? The PRF & the frequency are unrelated
Answer: True
⤳PRF & frequency = unrelated | PRF determined only by depth of view
↳ frequency determined by the characteristics of the transducer
172. . The PRF is the
a. product of the wavelength & propagation speed
b. reciprocal of the period
c. sum of pulse duration & listening time
d. reciprocal of PRP
Answer: D. reciprocal of PRP
↳
Example: if the PRF = 100 per second
⤏ then PRP = 1/100th of a second
✓ if system creates 500 pulses ,per second ⤏ PRP = 1/500 of a second
173. What’s a typical value for DF [aka duty cycle] of pulsed sound waves used in diagnostic imaging?
a. 0.001 msec
b. 0.001 kg/cm^3
c. 0.75
d. 0.001
Answer: D. 0.001
↳ DF [duty cycle] = % or fraction of timeUS system produces an acoustic
signal / is transmitting
✓ US transducers spend vast majority of time receiving
*** only small fraction of time transmitting an acoustic signal
174. What is the value of the duty cycle for continuous wave [CW] ultrasound?
A. 100
B. 1 %
C. 1000%
D. none of the above
Answer: D. none of the above
⤏DF for continuous wave US = 1.0 or 100%
↳ transducer produces acoustic signal @ all times
*Choices A, B & C
do not indicate this!
✓ 100 is not 100% _ 1% = 1/100th & incorrect _ 1000% = 10x & false
175. In the case of pulsed ultrasound, what is the maximum value of the duty factor?
A. 100%
B. 1
C. less than 100%
D. none of the above
Answer: C. less than 100%
---
*[tricky question]*
↳ Working w/ pulsed US system requires @ least a tiny bit of time listening & not
transmitting
✓ % of time transmitting must = less than 1 or 100% ⤏ if % = 100%, system = continuous wave
*** C. differentiates PW from CW ⤏states max value of DF of pulsed system must = ⇊
100%
176. While using a particular imaging system, what happens to the DF when depth of view increases?
A. Increases
B. decreases
C. unchanged
Answer: B. decreases
⤏DF & depth of view = inversely related
↳ system images deeper & needs ⇈ reflection listening time
✓ DF: fraction or % of time imaging system transmits
➟ DF = PD ÷ PRP
*** Normally, PD never changes | as depth of view ⇈
⤏ PRP ⇈ too
177. True or False? The sonographer alters the DF when adjusting the max imaging depth of a scan
Answer: True
⤏The DF = % of time that an US system is creating an acoustic wave
↳ DF & depth of view = inversely related |
178. T or F?
*DF ⇊ when depth of view ⇈
DF = US & probe system attribute & � change given system components = unchanged
Answer: False
↳ DF changes when sonographer adjusts max imaging depth
during an exam
179. Using the same US machine & probe, which of the following can a sonographer alter? *[all apply]
A. PRP
B. PRF
C. Frequency
D. duty cycle
E. pulse duration
Answer: A, B & D | PRP, PRF & DF
↳ when adjusting desired max imaging depth in exam ⤏adjust PRP & PRF | DF is also altered
✓ C. frequency & E. PD = fixed once transducer is selected ⤏both parameters can’t be altered
180. Which of the following terms does not belong with the others?
A. increased depth of view
B. increased duty factor
C. increase PRP
D. decreased PRF
Answer: B. increased duty factor
↳
imaging
⇈ DF’s = related to shallow imaging
|
⤏ A, C & D = consistent with deeper
181. Which of the following terms does not belong with the others?
A. increased depth of view
B. decreased duty factor
C. increase PRP
D. decreased SPL
Answer: D. decreased SPL
↳ SPL & alterations in depth of view = unrelated
|
⤏ A, B & C = all related to deeper imaging
182. What’s vital about describing sound beam intensities in various ways w/ regard to space & time?
A. it allows better transducer design
B. it’s important when studying bioeffects
C. it optimizes image quality
D. harmonics can be measured
Answer: B. it’s important when studying bioeffects
↳ describing intensities of sound beams as they vary in time & space =
vital to study bioeffects
183. Which intensity is most closely correlated to tissue heating?
A. SPTP
B. SATP
C. SPTA
D. SPTA
Answer: C.
elevation
SPTA ↳ SPTA intensity relates most closely to tissue temperature