Validation of theoretical diffraction correction functions for strongly focused high frequency ultrasonic transducers

Area of Science:

• Acoustical physics
• Ultrasonic imaging
• Metrology

Background:

• Accurate measurement of device-independent acoustical parameters requires correction for diffraction effects.
• This is particularly crucial when using strongly focused beams in high-frequency ultrasound applications.
• Existing methods for diffraction correction may introduce significant errors.

Purpose of the Study:

• To determine diffraction correction function profiles for two specific high-frequency focused transducers.
• To compare experimental results with a recent theoretical model for diffraction correction.
• To evaluate the accuracy of a common normalization procedure for diffraction correction.

Main Methods:

• Experimental determination of diffraction correction profiles using ultrasonic tissue-equivalent calibrating phantoms.
• Theoretical calculation of diffraction correction profiles based on established models.
• Comparison of experimental and theoretical results for 50 MHz and 29 MHz focused transducers.

Main Results:

• Excellent agreement was achieved between experimental measurements and the theoretical model.
• No statistically significant difference was found in mean backscattered power between experimental and theoretical approaches.
• A simple normalization procedure was shown to introduce significant errors in diffraction correction.

Conclusions:

• The validated theoretical model accurately predicts diffraction correction profiles for focused ultrasonic transducers.
• Experimental validation confirms the reliability of the theoretical approach.
• The commonly used normalization method for diffraction correction is unreliable and should be avoided.