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ultrasound physics..
chapter 4
| Question | Answer |
|---|---|
| What is the distance a pulse occupies in space from the start of the pulse to the end of the pulse? | spatial pulse length |
| What is the time from the start of one pulse to the start of the next pulse? | pulse repetition period |
| What is the fraction of percentage of the time the system is transmitting a pulse? | duty factor |
| What is the number of pulses that a system transmits each second? | pulse repetition frequency |
| What unit is associated with Pulse Repetition Period? | microseconds |
| What unit is associated with Spatial Pulse Length? | millimeters |
| What unit is associated with Duty Factor? | percent |
| What unit is associated with Pulse Repetition Frequency? | Hz |
| What unit is associated with Pulse Duration? | microseconds |
| Which pulsed wave parameters can the sonographer adjust? | pulse repetition period, pulse repetition frequency, duty factor |
| By changing the depth of view, can the sonographer change the pulse duration. | no |
| Which of the following pulse repetition frequency values would have the longest pulse repetition period? A) 1 kHz B) 2,000 Hz C) 4 kHz D) 6 Hz | d) 6Hz |
| Which of the following pulse repetition frequencies has the shortest pulse repetition period? A) 5,000 Hz B) 12 kHz C) 20 kHz D) 1 kHz | c) 20kHz |
| What happens to the duty factor when the pulse repetition frequency increases provided all other factors remain unchanged? | increases |
| Using the formula Duty Factor = Pulse Duration / Pulse Repetition Period" x 100;, what is the duty factor if the pulse duration is 1 microsecond and the pulse repetition period is 1 ms? | .1% |
| When the sonographer changes the depth of view, which of the following will remain unchanged? A) PRF B) propagation speed C) PRP D) duty factor | b) propagation speed |
| The sonographer changes the transducer from a 3 MHz to a 6 MHz transducer but does not change the imaging depth. Which of the following will remain unchanged? A) period B) frequency C) wavelength D) intensity | d) intensity |
| Based upon the SPL formula of SPL = c/f x # of cycles in the pulse, if the frequency increases, what happens to the SPL? | it decreases |
| Based upon the SPL formula of SPL = c/f x # of cycles in the pulse, if the number of cycles in the pulse decreases, what happens to the SPL? | it decreases |
| Based upon the SPL formula of SPL = c/f x # of cycles in the pulse, if the propagation speed increases, what happens to the SPL? | it increases |
| Based upon the formula, DF= PD/PRP, if the PRP decreases, what happens to the DF? | it decreases |
| . Based upon the formula, PRP = 1/PRF, if the PRF increases, what happens to the PRP? | it decreases |
| What might the sonographer have done if the PRF increased? | the sonographer changed to a shallower depth |
| What are the seven parameters that define sound wave? | Period, frequency, amplitude, power, intensity, wavelength, propagation speed |
| Which of the seven parameters can be changed or adjusted by the sonographer? | amplitude, power and intensity |
| What is the relationship between period and frequency? | inversely related, reciprocals |
| What is the relationship between power and amplitude? | power is proportional to the waves amplitude squared |
| How are power and intensity related? | proportional |
| How are wavelength and frequency related? | inversely related |
| What is the wavelength of 2MHz in soft tissue? | 0.77mm |
| Continuous wave | talks and listens at the same time, duty factor of 1 |
| pulsed wave | short bursts (pulses of acoustic energy) Duty factor of less than one |
| pulse duration | actual time from start of a pulse to end of pulse |
| pulse repetition period | time from the start of one pulse to the start of the next pulse |
| pulse repetition frequency | number of pulses that an ultrasound system transmits into the body each second |
| Spatial pulse length | distance that a pulse occupies in space from start to end of pulse |
| duty factor | percentage or fraction of time that a system is transmitting a pulse |
| What PW factors can be changed or altered by a sonographer? | pulse repetition period, pulse repetition frequency, duty factor |
| What are the typical values for pulse repetition frequency? | 1,000- 10,000 hertz |
| How are pulse repetition period and pulse repetition frequency related? | inversely related (reciprocal) |
| Duty factor of 0 | transducer is silent |
| What will cause duty factor to increase? | imaging at a more shallow depth |
| what will cause the duty factor to decrease? | imaging at a greater depth |
Created by:
AshleyLemieux