Rationale and derivation of MI and TI--a review

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Acoustics

Background:

• Diagnostic ultrasound equipment safety relies on monitoring acoustic output.
• The "Output Display Standard" (ODS) by AIUM/NEMA (1998) specifies real-time display of thermal and mechanical indices.
• Understanding the formulas behind these indices is crucial for accurate interpretation and safe use.

Purpose of the Study:

• To provide a comprehensive review of the rationale and derivation for the mechanical index (MI) and thermal index (TI) formulas.
• To expand upon the summary information presented in Appendix A of the ODS.
• To serve as a reference for the underlying principles and experimental data influencing these safety indices.

Main Methods:

• Review of existing literature and root publications detailing the derivation of MI and TI formulas.
• Explanation of the mathematical models and their reliance on experimental data.
• Cross-referencing with the AIUM/NEMA 1998 "Output Display Standard" (ODS).

Main Results:

• Detailed mathematical review of the MI and TI models is provided in the "Models and Derivation Notes" section.
• Key aspects of the MI and TI models are shown to be heavily dependent on experimental results.
• The review clarifies the origin and basis of the acoustic output indices displayed on ultrasound equipment.

Conclusions:

• The mechanical index (MI) and thermal index (TI) formulas are rigorously derived and based on experimental evidence.
• This review enhances understanding of the ODS by detailing the foundational science behind MI and TI.
• Accurate knowledge of these indices supports the safe and effective application of diagnostic ultrasound technology.