  As an emerging medical diagnostic technology, photoacoustic imaging has been
implemented for both preclinical and clinical applications. For clinical
convenience, a handheld free scan photoacoustic tomography (PAT) system
providing 3D imaging capability is essentially needed, which has potential for
surgical navigation and disease diagnosis. In this paper, we proposed a free
scan 3D PAT (fsPAT) system based on a handheld linear array ultrasound probe. A
global positioning system (GPS) is applied for ultrasound probes coordinate
acquisition. The proposed fsPAT can simultaneously realize real time 2D
imaging, and large field of view 3D volumetric imaging, which is reconstructed
from the multiple 2D images with coordinate information acquired by the GPS. To
form a high quality 3D image, a dedicated space transformation method and
reconstruction algorithm are used and validated by the proposed system. Both
simulation and experimental studies have been performed to prove the
feasibility of the proposed fsPAT. To explore its clinical potential, in vivo
3D imaging of human wrist vessels is also conducted, showing clear subcutaneous
vessel network with high image contrast.
