A dual mode imaging fiberscope system for colon cancer diagnosis

This paper presents an all fiber optic endoscope system working in double modalities of normal imaging and fluorescence spectrum analysis, for the diagnosis of colon cancer. A coherent laser source is used here for providing the simultaneous illumination (for normal imaging mode) and excitation of fluorophores (for fluorescence spectrum analysis mode). The design aspects of the fiberscope distal end with two illumination/excitation fibers for large area interrogation and a fiber bundle based imaging system is discussed here. The two illumination/excitation fibers are oriented at equal angles from their respective optic axis for providing the maximum illumination/excitation of the test target area in line with the optic axis of the fiberscope probe. The probe elements consist of a ball lens at the probe distal end, a high resolution image fiber, and an objective lens at the probe proximal end. Separate detection systems are provided for displaying the image / analyzing the fluorescence spectrum. Experiments were carried out with the developed fiberscope system by employing a prototype colon phantom sample as the test specimen. In the normal imaging mode, the abnormal areas in the phantom colon model are identified by looking at the protrusions in the reflected image. In the fluorescence spectrum analysis mode, these areas of abnormalities depicting cancerous growths showed a decrease in emitted intensity as compared to the normal areas.