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CSA C22.2 No. 60601-2-37-08 (2019) – Safety and Performance of Ultrasonic Medical Diagnostic and Monitoring Equipment
Comprehensive Guide to the Canadian Standard for Medical Electrical Equipment
CSA C22.2 No. 60601-2-37-08 (2019) is the Canadian adoption of IEC 60601-2-37, the international standard for the basic safety and essential performance of ultrasonic medical diagnostic and monitoring equipment. This standard applies to equipment used in medical imaging, fetal monitoring, and therapeutic ultrasound applications within the scope of the IEC 60601 series. As a critical part of the Canadian Electrical Code framework, it ensures that ultrasonic devices marketed in Canada meet rigorous safety and performance criteria, protecting patients and operators alike.
Scope and Application
The standard covers medical electrical equipment that uses ultrasonic energy for diagnostic imaging (e.g., B-mode, M-mode, Doppler) and physiological monitoring (e.g., fetal heart rate monitors). It specifies particular requirements that supplement or modify the general requirements of CSA C22.2 No. 60601-1. The scope includes both transcutaneous and intracavitary probes, as well as accessories such as gel pads and standoff pads. Excluded are devices used for therapeutic purposes (e.g., high-intensity focused ultrasound HIFU) unless they also incorporate diagnostic functions.
Tip: Manufacturers should verify that their product classification aligns with the definitions in Clause 201.3 of the standard, as many exemptions and additional testing requirements depend on the intended use.
Applicable equipment must comply with all relevant marking, documentation, and performance requirements, including those related to ultrasonic output limits, essential performance under fault conditions, and electromagnetic compatibility (EMC). The standard is harmonized with Health Canada’s Medical Devices Regulations and is recognized as a safety standard for certification by accredited bodies such as CSA Group and UL.
Key Technical Requirements
Ultrasonic Output Limits
One of the core requirements is the limitation of ultrasonic output to prevent bioeffects. The standard defines maximum values for:
- Mechanical Index (MI) – to avoid cavitation effects.
- Thermal Index (TI) – to prevent excessive tissue heating, with separate limits for soft tissue (TIS), bone (TIB), and cranial applications (TIC).
- Spatial-Peak Temporal-Average Intensity (ISPTA) – for thermal effects.
- Spatial-Peak Pulse-Average Intensity (ISPPA) – for mechanical effects.
| Parameter | Maximum Allowable Value | Applicable Condition |
|---|---|---|
| Mechanical Index (MI) | ≤ 1.9 | All diagnostic modes except ophthalmic |
| Soft Tissue Thermal Index (TIS) | ≤ 2.0 | General imaging, ≤ 3.0 for fetal scanning |
| Bone Thermal Index (TIB) | ≤ 2.0 | When beam passes through or near bone |
| Cranial Thermal Index (TIC) | ≤ 2.0 | Transcranial applications |
| ISPTA | ≤ 720 mW/cm² | Derated, for all modes |
| ISPPA | ≤ 190 W/cm² | Derated, pulse average |
Warning: Output limits must be measured under worst-case conditions using the test methods specified in Annex AA. Users must be provided with real-time display of MI and TI values on the system screen for all active imaging modes.
Essential Performance
The standard requires that essential performance characteristics be maintained under normal and single-fault conditions. For ultrasound equipment, essential performance includes:
- Image quality – adequate spatial resolution, contrast, and depth of field for diagnostic tasks.
- Distance measurement accuracy – typically within ±5% or better.
- Doppler velocity accuracy – within ±10% or ±5 cm/s, whichever is greater.
- Monitoring alarms – correct activation for loss of signal, overheating, or sensor fault.
Implementation Considerations for Manufacturers
Integrating compliance with CSA C22.2 No. 60601-2-37-08 into the design process requires careful attention to both hardware and software. Key aspects include:
- Output control algorithms – Systems must automatically reduce output when limits are approached, often using software-based safety interlocks.
- Acoustic output measurement – Manufacturers must perform hydrophone measurements in a water tank to characterize the acoustic field, as described in the standard’s test methodology.
- User interface design – The continuous display of MI and TI is mandatory; some modes also require display of ISPTA.
- Risk management – IEC 60601-1 and ISO 14971 apply; the standard requires a risk analysis specifically addressing ultrasonic bioeffects.
Success factor: Early integration of output limit checks into the product development cycle can reduce costly redesigns. Using a certified acoustic measurement laboratory for pre-compliance testing accelerates the certification process.
Compliance and Certification Requirements
To market ultrasonic medical equipment in Canada, manufacturers must demonstrate conformity to CSA C22.2 No. 60601-2-37. The process typically involves:
- Technical documentation – Including design specifications, risk management file, test reports (e.g., EMC, electrical safety, ultrasonic output), and clinical evaluation if applicable.
- Type testing – Performed by an accredited laboratory (e.g., CSA, Intertek, TÜV SÜD) to verify compliance with all safety and performance clauses.
- Quality system certification – ISO 13485 and/or CSA’s Medical Devices Program may be required depending on the device classification (Health Canada Class II, III, or IV).
- Certification marks – Once testing is complete, the manufacturer can apply the CSA Mark or another SCC-accepted mark to indicate compliance.
Non-compliance risk: Devices that do not meet the output limits or fail to display MI/TI may be subject to recall, fines, or market withdrawal by Health Canada. Additional penalties apply for failure to maintain ongoing compliance after certification.
The standard also includes requirements for accompanying documents (instructions for use, technical descriptions) and marking (ratings, probe compatibility). Periodic surveillance audits by the certification body ensure continued compliance throughout the product lifecycle.
Frequently Asked Questions
Q: Does CSA C22.2 No. 60601-2-37-08 apply to ultrasound equipment used only for veterinary purposes?
A: No, the standard is specifically for human medical use. Veterinary devices fall under separate standards (e.g., CSA C22.2 No. 60601-1-6). However, many manufacturers voluntarily apply the same safety principles for consistency.
A: No, the standard is specifically for human medical use. Veterinary devices fall under separate standards (e.g., CSA C22.2 No. 60601-1-6). However, many manufacturers voluntarily apply the same safety principles for consistency.
Q: Is there a separate standard for therapeutic ultrasound devices?
A: Yes, therapeutic equipment (e.g., HIFU, physiotherapy ultrasound) is covered by CSA C22.2 No. 60601-2-5 (IEC 60601-2-5) for safety and IEC 60601-2-62 for essential performance. The two standards have different output limits and risk control requirements.
A: Yes, therapeutic equipment (e.g., HIFU, physiotherapy ultrasound) is covered by CSA C22.2 No. 60601-2-5 (IEC 60601-2-5) for safety and IEC 60601-2-62 for essential performance. The two standards have different output limits and risk control requirements.
Q: Can a manufacturer use an IEC 60601-2-37 test report from a European lab for Canadian certification?
A: Yes, provided the lab is accredited by a recognized organization (e.g., ILAC) and the report covers all clauses of the CSA version. However, some national deviations (e.g., for mains voltage and marking language) must be verified.
A: Yes, provided the lab is accredited by a recognized organization (e.g., ILAC) and the report covers all clauses of the CSA version. However, some national deviations (e.g., for mains voltage and marking language) must be verified.
Q: What is the transition period if a new edition of IEC 60601-2-37 is published?
A: CSA typically adopts new editions within 12–18 months of IEC publication. A transition period of 3–5 years is set by the SCC, during which both editions may be used. Manufacturers are advised to monitor changes and plan for redesign early to maintain market access.
A: CSA typically adopts new editions within 12–18 months of IEC publication. A transition period of 3–5 years is set by the SCC, during which both editions may be used. Manufacturers are advised to monitor changes and plan for redesign early to maintain market access.
This article is for informational purposes and does not constitute legal or compliance advice. Consult a certified testing laboratory and regulatory authority for specific guidance. Last updated: 2026.