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The principle of ultrasound: Difference between revisions
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'''Pulse Repetition Period''' or PRP is the time between the onset of one pulse till the onset of the next pulse. Aagain, it is measured in units of time. This parameter includes the time the pulse is “on” and the listening time when the ultrasound machine is “off”. It can be changed by the sonographer by varying the depth to which the signal is send. Since the Pulse Duration time is not changed, what is changed is the listening or the “dead time”. PRP = 13 microseconds x the depth of view (cm). It follows from this equation that the deeper is the target, the longer is the PRP. The typical values of PRP in clinical echo are form 100 microseconds to 1 millisecond. | '''Pulse Repetition Period''' or PRP is the time between the onset of one pulse till the onset of the next pulse. Aagain, it is measured in units of time. This parameter includes the time the pulse is “on” and the listening time when the ultrasound machine is “off”. It can be changed by the sonographer by varying the depth to which the signal is send. Since the Pulse Duration time is not changed, what is changed is the listening or the “dead time”. PRP = 13 microseconds x the depth of view (cm). It follows from this equation that the deeper is the target, the longer is the PRP. The typical values of PRP in clinical echo are form 100 microseconds to 1 millisecond. | ||
[[File:PhysicsUltrasound_Fig8.svg|thumb|left|500px| Fig. 8]] | |||
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A related parameter to PRP is the '''Pulse Repetition Frequency''' or PRF. PRP and PRF are reciprocal to each other. PRF is the number of pulses that occur in 1 second. This parameter [[is not related to the frequency]] of ultrasound. PRF can be altered by changing the depth of imaging. It is measured in Hertz (Hz). PRF = 77,000 / depth of view (cm). As evident from the equation, as the location of the target gets further away, the PRF decreases. PRF is related to frame rate or sampling rate of the ultrasound. | A related parameter to PRP is the '''Pulse Repetition Frequency''' or PRF. PRP and PRF are reciprocal to each other. PRF is the number of pulses that occur in 1 second. This parameter [[is not related to the frequency]] of ultrasound. PRF can be altered by changing the depth of imaging. It is measured in Hertz (Hz). PRF = 77,000 / depth of view (cm). As evident from the equation, as the location of the target gets further away, the PRF decreases. PRF is related to frame rate or sampling rate of the ultrasound. | ||