On the Early Diagnosis of Cancer Using Ultrafast Laser Spectrum Technique

The ultrafast photodynamic processes of hematoporphyrin derivative (HPD) used for the diagnosis of the cancer is studied in this paper. Fluorescence spectra, fluorescence decay characteristics and the variation curves of fluorescence peak intensity with time of the cancerous and normal cells incubated by HPD were measured using an ultrashort pulses laser spectral technique and the picosecond time-correlated single-photon counting system. It is found that the cancerous cell specimens have special fluorescence spectra peak near 645 nm; the fast component of the cancerous and normal cells fluorescence decay are approximately 150ps and 300ps; fluorescence peak intensity of the cancerous and normal cells are decayed about 10% and 55% after 12 hours respectively. Analyzing the measured curves of fluorescence spectra and time-resolved fluorescence decay, we can calculate that HPD concentration inside the cancerous cells is about one hundred times higher than that inside the normal cells; the lifetimes of the cancerous and normal cells are about 824ps and 1798ps respectively; and retention time of HPD inside the cancerous and normal cells are about 17 days and 6 days.