IEC 61685 pdf download

IEC 61685 pdf download Ultrasonics – Flow measurement systems – Flow test object
1 scope
This International Standard specifies parameters for a flow Doppler test object representinga blood vessel of known diameter at a certain depth in human tissue, carrying a steady flow.
This International Standard establishes a flow Doppler test object which can be used toassess various aspects of the performance of Doppler diagnostic equipment.
2Normative references
The following normative documents contain provisions which,through reference in this text,constitute provisions of this International Standard. For dated references,subsequentamendments to, or revisions of,any of these publications do not apply.However, parties toagreements based on this International Standard are encouraged to investigate the possibilityof applying the most recent editions of the normative documents indicated below.For undatedreferences, the latest edition of the normative document referred to applies. Members of lECand ls0 maintain registers of currently valid lnternational Standards.
IEC 61206:1993,Ultrasonics – Continuous-wave Doppler systems – Test procedures
IEC 61102:1991，Measurement and characterisation of ultrasonic fields using hydrophones inthe frequency range 0,5 MHz to 15 MHz
IEC 61895:1999，Ultrasonics – Pulsed Doppler diagnostic systems – Test procedures todetermine performance
Definitions
For the purposes of this International Standard, the following definitions apply:
3.1
-3 dB Doppler frequency
frequency at which the power per unit frequency in the Doppler spectrum is half (-3 dB) of themaximum value
3.2
-3 dB sample volume
volume of a region in space for which the Doppler system gives a response to a point Dopplertarget that is above -3 dB from the maximal response, taking account of the effects of bothtransmission and reception
Unit: cubic millimetre, mm3
3.3
-3 dB sample volume length
largest dimension of the -3 dB sample volume in the direction of the beam alignment axis(see 3.5 of lEC61102)
Unit: millimetre, mm
3.4
-3 dB sample volume width
largest value of the dimension of the -3 dB sample volume along an axis which isperpendicular to the beam alignment axis. In case the Doppler system has a scan plane, theaxes are taken in the scan plane and perpendicular to the scan plane
Unit: millimetre, mm
3.5
acoustic-working frequency
frequency of an acoustic signal based on the output observed by a hydrophone placed in anacoustic field: it is the arithmetic mean of the two frequencies at which the amplitude of theacoustic pressure spectrum is 3 dB below the peak amplitude
[conforms to 3.4.2 of lEC 61102]
Unit: hertz,Hz
3.6
aliasing
false indication of signal frequency as a result of sampling at too low a frequencyNOTE The threshold for aliasing depends on pulse repetition frequency and a possible base line shift.
3.7
average frequency of the Doppler spectrum
parameter estimated by clinical Doppler systems for the short-time average in a Dopplerspectrum, ignoring the contributions from noise
NOTE The average frequency of the Doppler spectrum is generally determined for a small time interval,typically 2 ms to 20 ms).
Unit: hertz,Hz
3.8
axial response range
depth range in tissue over which a signal from a specific target plus noise is at least 3 dBabove the noise level
[see 2.4.1 of lEC 61206]Unit: millimetre, mm