Trends in diagnostic ultrasound exposure

Area of Science:

• Medical Physics
• Biomedical Engineering
• Diagnostic Imaging

Background:

• Diagnostic ultrasound technology has advanced significantly.
• Understanding exposure levels is crucial for safety and efficacy.
• Previous studies indicate a need for updated exposure data.

Purpose of the Study:

• To present current trends in diagnostic ultrasonic equipment exposure.
• To survey contemporary exposure values for various ultrasound modes.
• To analyze the relationship between equipment operation and exposure levels.

Main Methods:

• Analysis of trends in time-averaged intensities and peak pressures over two decades.
• Measurement of average worst-case rarefaction pressure (p-) for available diagnostic equipment.
• Quantification of average spatial-peak time-averaged intensities (I(SPTA)) across different operating modes (pulsed Doppler, M-mode, color Doppler, imaging).
• Comparison of exposure levels from vaginal transducers versus other types.
• Investigation into exposure measurement complexities on color Doppler systems.

Main Results:

• Both time-averaged intensities and peak pressures have steadily increased over the last 20 years.
• Average worst-case rarefaction pressure (p-) is approximately 2 MPa in water, independent of the mode.
• Highest p- values are observed in short-focus beams.
• Pulsed Doppler operation exhibits the highest average spatial-peak time-averaged intensities (I(SPTA)), exceeding 1 W cm-2.
• M-mode and color Doppler average I(SPTA) are around 100 mW cm-2, while imaging is an order of magnitude lower.
• Vaginal transducers show similar operational exposure to other types.

Conclusions:

• Diagnostic ultrasound equipment exhibits a consistent upward trend in energy output.
• Pulsed Doppler mode presents the highest intensity exposure, necessitating careful consideration.
• Understanding scanner control effects is vital for accurate exposure assessment in color Doppler systems.