3D Photoacoustic computed tomography with null subtraction

We present a computational method to enhance elevational resolution in 3D photoacoustic computed tomography (PACT) using a linear transducer array. By combining 2D synthetic aperture imaging with a null subtraction approach, we apply post-processing apodization to generate a synthetic null beam in the elevational direction. Subtracting this from two offset-focused images sharpens elevational features and improves resolution in 3D PACT imaging. Experiments with tissue-mimicking phantoms demonstrate enhanced elevational resolution and contrast compared to the conventional delay and sum (DAS) method. This method provides a practical and efficient solution that can be broadly applied to most 3D PACT systems.