Quantification of the Effect of Array Element Pitch on Imaging Performance.

Area of Science:

• Medical Imaging
• Acoustics
• Array Signal Processing

Background:

• Periodic ultrasonic arrays are crucial for medical imaging.
• Grating lobes are imaging artifacts caused by discrete spatial sampling.
• Classical Nyquist rules offer limited guidance for practical, finite-aperture, broadband arrays.

Purpose of the Study:

• To investigate the relationship between ultrasonic array element pitch and imaging performance.
• To develop a theoretical framework for quantifying grating lobe artifacts.
• To establish practical design guidelines for ultrasonic arrays.

Main Methods:

• Developed a theoretical framework to decompose the point spread function into main and grating lobes.
• Utilized numerical simulations to analyze 1-D linear arrays in near-field and far-field scenarios.
• Validated findings with experimental examples.

Main Results:

• Established a method for unambiguous quantification of grating lobe artifacts.
• Demonstrated that classical Nyquist rules are often overly conservative.
• Showed that increased array pitch is feasible with specific algorithmic constraints on ray angles.

Conclusions:

• Array element pitch can be optimized beyond traditional Nyquist criteria for enhanced imaging.
• The developed framework allows for precise control over grating lobe levels in array design.
• Practical design guidelines are provided for optimizing ultrasonic array performance.