A FLUORESCENCE IMAGING DEVICE FOR ENDOSCOPIC DETECTION OF EARLY STAGE CANCER – INSTRUMENTAL and EXPERIMENTAL STUDIES

Abstract Visible detection of early stage cancer labelled with the fluorescing porphyrin mixture of dihematoporphyrin‐ether and dihematoporphyrin‐ester (DHE) is often limited by a high and inhomogeneously distributed level of autofluorescence. A new imaging method for reducing autofluo‐rescence is described. The method uses alternating fluorescence excitation with laser light in the violet and blue spectral ranges. Subtraction of the corresponding fluorescence images results in contrast enhancement due to an effective reduction in the autofluorescence contribution. A prototype version of a highly sensitive fluorescence imaging device including a modified krypton ion laser, an image‐intensified solid‐state TV‐camera, a digital image‐processing system, and video recording and monitoring has been developed.