Influence on imaging qualities of photoacoustic tomography caused by mismatch of ultrasonic velocities

In this paper, Influences of the acoustic path difference on photoacoustic(PA) images caused by mismatch of ultrasonic velocities were studied. We first proposed using the concentration-adjustable glycerite as an ultrasonic transmitting medium. By switching a appropriate concentration of the glycerite.. it can make the velocities of the PA signals keep constant between transmitting medium and biological tissues, and avoid the acoustic path difference (APD) in image reconstruction. The experiments demonstrate that the acoustic path difference influences the imaging qualities badly: especially. the spatial resolution of PA image is extremely reduced. After matching ultrasonic velocity by glycerite the contrast of the reconstructed image is improved greatly and the background artifacts are reduced obviously The spatial resolution of the reconstructed image is improved from 0.5mm to 0.15mm. It has great practical significance for applying photoacoustic tomography to noninvasive clinic diagnosis of cancer.