Multiview Hilbert transformation for full-view photoacoustic computed tomography using a linear array

Due to their low cost, hand-held convenience, wide selection of bandwidths, and ultrasound imaging capability, linear ultrasonic transducer arrays have been widely studied for photoacoustic computed tomography (PACT). As linear-array PACT suffers from a limited view, full-view imaging requires either the transducer or the object to be rotated. So far, both the central frequencies and bandwidth of linear transducer arrays applied in full-view PACT are low, limiting the spatial resolutions of the reconstructed images. Here, we present a multiview high-frequency PACT imaging system implemented with a commercial 40-MHz central frequency linear transducer array. By rotating the object through multiple angles with respect to the linear transducer array, we acquired full-view photoacoustic pressure measurements. Further, to quantify the unipolar initial pressures and overcome the limitations of the single-view Hilbert transformation, we developed a multiview Hilbert transformation method. The in-plane spatial resolution of this full-view linear-array PACT was quantified to be isotropically 60 μm within a 10×10 mm2 field of view. The system was demonstrated by imaging both a leaf skeleton and a zebrafish in vivo.