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Hematoporphyrin derivative (HPD) can selectively accumulated in cancerous tissues. Illuminated by a certain wavelength of light, it will emit a red fluorescence which has peaks at 630nm and 690nm. With this character HPD is used to detect and localize malignant tumors. A spectroscopic instrument, optical multichannel analyzer (OMA) recorded the shape and the intensities of the fluorescence. A 580nm filter was used to block any scattered excitation light. HPD has its adverse effect named cutaneous phototoxicity which produces erythema, edema, and more seriously, blistering due to its high concentration in skin. In our experiment, we divided 60 Kunming mice with s-180 sarcoma to three groups. Two groups were injected a small dose, 2mg/kg and normal dose, 5mg/kg of HPD, respectively. The third group were left intact. Referring to the standard curve of HPD previously recorded, we could tell where the cancerous tissues were according to the spectrographs. This method detected 22/30(73%), 10/13(77%), and 1/14(7%) of tumors in groupi (2mg/kg), group2 (5mg/kg) and group3 (no HPD), respectively. Results of Chi-test showed no distinct differences between two HPD injected groups (p<O.O5). The fluorescence intensities of normal and cancerous tissues were studied and we found that the intensity ratios of cancerous tissues to normal tissues varied among the three groups. In group 1 and group2 they were 2.22±1 .59and 1.97±1.42 and t-test proved that distinct differences existed to the value 1.09±0.45 of group3. It seemed that in the cases of either injected with normal dose or small dose of HPD, the intensities of cancerous tissues will rise to a certain degree that much higher than that without injection. Keywords: laser, fluorescence, diagnosis
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