Direction of arrival filters for improved aberration estimation

Area of Science:

• Medical imaging
• Ultrasound technology
• Signal processing

Background:

• Accurate aberration profile measurement is crucial for successful adaptive imaging.
• Off-axis scatterers can introduce errors in aberration estimates.
• Existing methods may not fully suppress wavefronts from undesired directions.

Purpose of the Study:

• To enhance the accuracy of aberration profile estimation in adaptive imaging.
• To investigate the efficacy of two-dimensional spatial filters in suppressing off-axis wavefronts.
• To validate the improvements using simulations and experimental phantoms.

Main Methods:

• Application of two-dimensional spatial filters to radiofrequency (rf) signals of individual array elements.
• Utilizing spatial filtering to reject wavefronts from angles outside the primary look direction.
• Employing adaptive spatial filtering for further refinement of aberration estimates.

Main Results:

• Spatial filtering demonstrably reduced errors in measured aberration profiles.
• Adaptive spatial filtering provided further significant improvements in aberration estimation accuracy.
• Increased element-to-element correlation was observed after applying spatial filters.

Conclusions:

• Two-dimensional spatial filtering is an effective method for improving aberration estimation in adaptive imaging.
• The proposed adaptive spatial filtering technique enhances accuracy and is validated by simulations and phantom experiments.
• This technique shows promise for application in real-world medical imaging, such as in vivo human thyroid scans.