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Ch.4-Des Pulse Waves
Ultrasound Physics
| Question | Answer |
|---|---|
| Short bursts of acoustic energy are also known as _______. | pulses |
| Pulse duration is the ______ ______ from the start of a pulse to the end of that pulse. | actual time |
| _______ ______ is reported in units of time, such as us, ms or seconds. | Pulse duration |
| The typical value of pulse duration in diagnostic ultrasound is what? | 0.3 to 2.0 us. |
| Pulse duration is determined by the: | sound source |
| Is pulse duration adjustable? | No |
| What is the formula for pulse diration? | # of cycles x period |
| Pulse duration is _______ related to the number of cycles. | directly |
| Pulse duration is _______ proportional to period. | directly |
| Pulse duration is _______ proportional to the frequency. | inversely |
| Which type of pulse is more desirable in diagnostic imaging? | short |
| What is the distance that a pulse occupies in space from the start to the end of a pulse called? | spatial pulse length |
| Spatial pulse length has units of what? | distance |
| What are the typical values of spatial pulse length in soft tissue? | from 0.1 to 1.0mm |
| What determines pulse length? | both the source and the medium |
| Is pulse length adjustable? | No |
| Spatial pulse length (mm)= | # cycles x wavelength (mm) |
| Spatial pulse length is _____ proportional to the number of cycles in the pulse. | directly |
| Spatial pulse length is ______ proportional to wavelength. | directly |
| Spatial pulse length is ________ proportional to frequency. | inversely |
| Pulse duration is the ______ that a pulse is "on" and is typically measured in microseconds. | time |
| Pulse length is the _________ of the pulse end to end, typically measured in millimeters. | distance |
| _______ ________ _______ is the time from the start of one pulse to the start of the next pulse. | Pulse repetiton period |
| Pulse repetition period is reported in untis of time, such as _____. | ms |
| Pulse repetition period is determined by the _________. | sound source |
| Can the sonographer adjust the pulse repetition period? | Yes |
| As depth of view increases, pulse repetition period _______. | increases |
| As depth of view decreases, pulse repetition period _______. | decreases |
| _________ ________ _______ is the number of pulses that an ultrasound system transmits into the body each second. | Pulse repetition frequency |
| Pulse repetition frequency is reported in units of ___. | Hz |
| The typical valu of pulse repetition frequency is: | 1,000 to 10,000 Hz |
| Pulse repetition frequency is determined by the _______. | source |
| Can the sonographer adjust the pulse repetition frequency? | Yes |
| As depth of view increases, pulse repetition frequency _____. | decreases |
| As depth of view decreases, pulse repetition frequency ______. | increases |
| An ultrasound machine is imaging to a depth of 2 cm. Would the pulse repetition frequency be described as high or low? | high |
| When the sonographer adjusts the depth of view to 20 cm, what happens to the pulse repetition frequency? | it is reduced |
| PRP and PRF are _______ related. | inversely |
| PRF x PRP= | 1 |
| What is the complementary metric unit for PRP? | seconds |
| What is the complementary metric unit for PRF? | hertz |
| True or False. Two waves can have identical pulse repetition frequencies, even if their pulse repetitoin periods are different. | False. Two waves can never have identical PRFs if their pulse repetition periods are different. |
| True or False. Two waves can have identical PRFs, even if their periods are different. | True. Period and pulse repetiton frequency are unrelated. |
| True or False. Two waves can have identical PRFs, even if their frequencies are different. | True. Frequency and pulse repetition frequency area unrelated. |
| True or False. PRF and pulse repetition period are determined only by the imaging depth. | True |
| What describes the percentage or fraction of time that the system is transmitting a pulse? | duty factor |
| What determines duty factor? | source |
| Is duty factor adjustable? | yes |
| Less listening, shorter PRP, higher PRF and higher duty factor= | shallow imaging |
| More listening, longer PRP, lower PRF and lower duty factor= | deeper imaging |
| When all other factors remain unchanged, what happens to the duty factor when the PRF increases? | increases |
| If all other factors remain unchanged, what happens to the duty factor when the PRP increases? | decreases |
| If all other factors remain unchanged, what happens to the duty factor when imaging depth increases? | decreases |
| If all other factors remain unchanged, what happens to the duty factor when the sonographer uses a new transducer with a longer pulse duration? | increases |
| What is the duty if the pulse duration is 1 us and the PRP is 1 ms? | 0.001 |
| ________ is the time from the start of a pulse to the end of that pulse. | Pulse duration |
| ________ is the time from the start of a pulse to the start of the next pulse. | Pulse repetition period |
| Pulse repetiton frequency is the reciprocal of _______. | pulse repetition period |
Created by:
jady1999