Time-domain reconstruction for thermoacoustic tomography in a spherical geometry

Area of Science:

• Biomedical Imaging
• Medical Physics
• Microwave Engineering

Background:

• Thermoacoustic tomography (TAT) offers non-ionizing imaging capabilities.
• Microwave-induced TAT (MITAT) leverages microwave absorption contrast in tissues.
• Spherical configurations can enhance data acquisition geometry for improved reconstruction.

Purpose of the Study:

• To develop and validate a reconstruction-based MITAT system in a spherical configuration.
• To assess the imaging performance, including spatial resolution, of the developed system.
• To demonstrate the feasibility of accurately reconstructing microwave absorption distributions in biological samples.

Main Methods:

• Utilized microwave pulses to excite thermoacoustic waves in biological tissue samples.
• Employed a wide-band unfocused ultrasonic transducer positioned on a spherical surface around the sample.
• Acquired data from multiple directions to enable tomographic reconstruction.
• Derived an exact reconstruction solution and approximated it using a modified backprojection algorithm.

Main Results:

• Successfully reconstructed images representing the microwave absorption distribution of biological samples.
• Demonstrated good agreement between reconstructed images and the original sample characteristics.
• Achieved a spatial resolution of 0.5 mm in the reconstructed images.

Conclusions:

• The presented spherical MITAT system is effective for reconstructing microwave absorption distributions.
• The system provides high-resolution imaging of biological tissues.
• The modified backprojection algorithm is suitable for this application, enabling accurate imaging.