IEC 61846:1998 pdf download – Ultrasonics – Pressure pulse lithotripters -Characteristics of fields

IEC 61846:1998 pdf download – Ultrasonics – Pressure pulse lithotripters -Characteristics of fields.
— lithotripsy equipment using extracorporeally induced pressure waves;
— lithotripsy equipment producing focused mechanical energy.
This International Standard does not apply to percutaneous and laser llthotripsy equipment
This International Standard specifies
— measurable parameters which could be used in the declaration of the acoustic output of extracorporeal lithotripsy equipment.
— methods of measurement and characterization of the pressure field generated by lithotripsy equipment.
NOTE — The parameters defined in Ins International Stari4ard do not — at the present time — alliow quantitative slements to be made about etiecliveneas end possible hazard In particular. ii not possible tO fllaIia a statement about the limits to, these effects
While this particular standard has been developed for equipment intended for use in lithotripsy, it has been developed such that, as long as no other specific standards are available to be used for other medical applications of therapeutic extracorporeal pressure pulse equipment, this standard may be used as a guideline,
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All normative documents are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below, Members of IEC and ISO maintain registers of currently valid International Standards.
IEC 60050{801):1994. International Electrofechn,cal Vocabulary (1EV) — Chapter 801: Acoustics and electroacoustics
IEC 60866:1987, Characteristics and calibration of hydrophones (or operation in the frequency range 0.5 MH to 15MHz
IEC 61102:1991, Measurement and characterisation of ultrasonic fields using hydrophones in the frequency range 0.5 MHz to 15 MHz
NOTE — Two different hydrophonu are permitted because many of those suitable for measurements at in. focus are very fragile. A more roOust. teas highly specIied devices merelore perm.tted lot general field measurements. Care Is to be taken. when e.leclng a field hythephon. to select a type which will provide the needed linearity and negativ, acoustic preasure readings of the high pressures encountered.
6.3 Voltage measurement
6.3.1 OscIlloscope or transient recorder
The device used to observe and measure the hydrophon. output signal shall be appropriate for the purpose, its frequency response and input capacitance and resistive impedance shall be reported. A digital oscilloscope with a sampling frequency greater than 100 MHz is the preferred option, although a transient recorder and digital storage for subsequent computer display may be satisfactory.
The end-of-cable loaded sensitivity of the hydrophone shall be determined as specified in 5.1.2 of IEC 61102. thiS value shall then be used to calculate the incident acoustic pressures from the observed hydrophone output voltages.
6.3.2 Pressure-pulse-waveform recording
The output voltage waveform from the hydrophone shall be recorded in such a way as to allow the measurement or calculation of:
— instantaneous acoustic pressure, p;
– peak-negativ. acoustic pressure, p_:
peak-posItiv, acoustIc pressure, p,;
— rise time. tr;
— compressional pulse duration.
— Instantaneous intensity, I.
7 Measurement procedure
The measurements shall be made at least at one clinical setting as specified by the manufacturer. It only one setting is used. this setting shall be the maximum available for clinical application. The settings used shall be documented.
Using the x-y-z coordinate positioning system, with the z direction being the beam axis, the following measurements shall be made to define the spatial characteristics of the beam.
The x axis shall be taken as the direction of the maximum beam width in the x-y plane which contains the focus. The distance between the focus and the target location shall be documented If the peak-positive acoustic pressure p in the target location does not differ by more than 10 % of p in the focus, It is feasible to do the measurements in the x-y plane at the z position indicated by the target location.