Overview
IEC 61846:1998 - "Ultrasonics - Pressure pulse lithotripters - Characteristics of fields" is an International Electrotechnical Commission standard that defines how to measure and describe the acoustic pressure fields produced by extracorporeal pressure-pulse lithotripsy devices. It applies to lithotripsy equipment that uses extracorporeally induced pressure waves or focused mechanical energy, and specifies measurable parameters, measurement methods, and characterization practices for declaring the acoustic output of such equipment. (It does not apply to percutaneous or laser lithotripsy.)
Key topics and requirements
- Scope and purpose: Standardizes parameters for reporting the acoustic field from pressure-pulse lithotripters to enable consistent characterization and comparison.
- Measurable parameters: Definitions and symbols for key quantities such as peak-positive (p+) and peak-negative (p–) acoustic pressure, compressional pulse duration, rise time, pulse-pressure-squared integral, derived pulse-intensity integral (PII), derived focal acoustic pulse energy (Ef), focal cross-sectional area (Af), focal volume (Vf) and focal widths/extent.
- Measurement conditions: Guidance to perform measurements under conditions approximating actual operation, including tank environment, degassed water at 20–40 °C, conductivity suitable for the hydrophone, and noting pulse drive level and pulse rate.
- Test equipment: Requirements for a suitable test chamber (water tank) and the use of calibrated hydrophones and voltage measurement equipment. Reference to hydrophone calibration and end-of-cable sensitivity.
- Procedures: Spatial and temporal measurement methods, including spatial mapping around the focus and time-domain capture of the pressure pulse waveform. Annexes provide practical information on wave types, transducer types and field measurement practices.
- Limitations: The standard explicitly notes that defined parameters do not, by themselves, quantify clinical effectiveness or hazards and do not establish safety limits.
Practical applications
- Manufacturers: Use IEC 61846 to declare acoustic output, design validation, and R&D for pressure-pulse lithotripters.
- Test laboratories: Implement standardized measurement procedures for device characterization, product comparison, and quality control.
- Regulators and notified bodies: Assess conformity of extracorporeal lithotripsy devices with internationally recognized measurement practices.
- Researchers and clinicians: Interpret device acoustic field data for performance assessment and comparative studies (while recognizing the standard does not set clinical exposure limits).
Related standards
- IEC 60866 - hydrophone characteristics and calibration
- IEC 61102 - ultrasonic field measurement with hydrophones
- IEC 60050(801) - acoustics vocabulary
Keywords: IEC 61846, lithotripsy, pressure pulse lithotripter, acoustic output, hydrophone calibration, focal acoustic energy, pressure field characterization, extracorporeal lithotripsy.