IEC 61685:2001

Overview

IEC 61685:2001 - "Ultrasonics - Flow measurement systems - Flow test object" defines the ultrasonic properties and parameters of a flow Doppler test object (a Doppler test phantom) intended for acceptance testing, quality assurance and clinical calibration of Doppler diagnostic systems. The standard covers a steady flow through a straight circular tube embedded at a known depth in tissue-mimicking material (TMM) and filled with a blood‑mimicking fluid (BMF). It is aimed at Doppler systems operating in the acoustic-working frequency range 2 MHz to 10 MHz.

Key topics and technical requirements

• Test-object architecture: general outline of the measurement section (tube + BMF + TMM), geometry and placement of the vessel-like tube.
• Blood-mimicking fluid (BMF): acoustic properties and stability requirements so that backscatter and attenuation simulate in vivo blood.
• Tissue-mimicking material (TMM): attenuation and scattering characteristics that represent human soft tissue at the specified frequencies.
• Ultrasonic parameters: definitions and measurement-related quantities such as acoustic-working frequency, –3 dB Doppler frequency, –3 dB sample volume (length/width), axial response range, depth of measurement, and Doppler angle.
• Performance aspects to assess: spectral fidelity (velocity spectrum), signal level vs. vessel size and depth, channel separation, aliasing behavior, dead‑zone, colour display spatial resolution and penetration.
• Material and labelling specifications: precautions to prevent BMF composition changes and required labelling information for test objects.
• Supporting information: formulae (Annex B), rationale for chosen values (Annex C), an example flow test object (Annex D), possible flow circuit (Annex E) and measuring methods (Annex F).

Practical applications

• Validate and calibrate Doppler diagnostic equipment for clinical use.
• Perform acceptance testing of new ultrasound systems and routine quality assurance (QA) checks.
• Evaluate system response to changes in vessel diameter, depth, and velocity spectrum - useful for verifying spectral accuracy, penetration and colour flow resolution.
• Reproduce controlled, repeatable test conditions for R&D, manufacturing QC and regulatory compliance testing.

Who should use this standard

• Ultrasound equipment manufacturers (design verification and production QA)
• Medical physics and clinical engineering departments (clinical calibration, QA)
• Independent test laboratories and conformity assessment bodies
• Regulatory authorities evaluating diagnostic ultrasound performance

Related standards

• IEC 61206:1993 - Continuous-wave Doppler test procedures
• IEC 61895:1999 - Pulsed Doppler diagnostic test procedures
• IEC 61102:1991 - Hydrophone-based ultrasonic field measurement

Keywords: IEC 61685, flow Doppler test object, Doppler phantom, blood‑mimicking fluid, tissue‑mimicking material, ultrasonics, Doppler calibration, quality assurance, 2–10 MHz.