Measurement of Photoacoustic Signals Originated from the Tumor Localizing Photosensitizer in Tissue Phantom :

Feasibility Study for Early Pancreatic Cancer Diagnosis

Abstract

A new photoacoustic diagnosis of early pancreatic cancer is proposed. In this method, pancreatic tissue is irradiated with pulsed light via a pancreatic duct, and photoacoustic signals originated from the tumor-localizing drug are detected. The validity of this method was investigated for two-layered gelatin models (top: normal tissue mimicking layer, bottom: tumor mimicking layer) whose optical properties were adjusted to be the same as those of pancreas in rats. With a detector in which an optical fiber and a ring-shaped piezoelectric film were coaxially arranged, photoacoustic signals came from the tumor mimicking layer were measured. It was shown that for a drug concentration ratio (normal tissue : tumor) of 1:3, signals came from 3 mm in depth could be detected, while for a ratio of 1:6, the detectable depth increased to 6 mm. The results suggest that the present method can be applied to diagnosis of deep-located early cancers.