Raman spectroscopy for the diagnosis of unlabeled and unstained histopathological tissue specimens

Figure 2 Measured points in the stomach cancer and normal tissue specimens. A: Normal stomach tissue specimen; B: Stomach cancer specimen. We established the conditions for laser output and laser irradiation time on a marginal part of an unstained tissue specimen that included both gastric cancer lesion and non-lesion areas. To prevent tissue degeneration, we reduced the laser power as much as possible, while maintaining detection of the Raman spectrum. Optimal measurement conditions were established as a laser output of 1.7 mW and an irradiation time of 10 s. We measured the tissue specimens at regular intervals from the mucous membrane to the submucosal layer.