Application of Autofluorescence Endoscopy for Colorectal Cancer Screening: Rationale and an Update

Figure 2

Schematic diagram of the AFI system [19]: white light emitted from a 300-W xenon lamp in the light source is separated with a rotary filter into an excitation light with a wavelength range of 390 to 470 nm and a green light of 540 to 560 nm wavelength. These fractionated lights radiate sequentially during the observation period. A barrier filter to remove reflected excitation light is set in front of a monochrome charge-coupled device. Light of 500 to 630 nm wavelength is selectively detected from both autofluorescence and reflected green light. A false color image is produced by allocating the detected and amplified autofluorescence signal to the green (G) channel and the reflected signal of green light to the red (R) and blue (B) channels in the ratio of 1 to 0.5.