Theoretical and experimental study on the difference of the time-resolved fluorescence spectrum between the tumor and the adjacent normal tissue

摘要

The objective of this paper is to study the difference of the time-resolved fluorescence spectrum between the tumor and the adjacent normal tissue. The time-resolved spectrum of the s-180 sarcoma tumor and adjacent normal tissue mediated by the Palladium-porphyrin photosensitizer (Pd-TCPP) is detected by a homemade instrumentation. An improved Monte Carlo algorithm, taking into account the depth of the upper layer tissue (z_1) and the delay of the fluorescence photon emission for the time (τ) Pd-TCPP electrons spend in the excited state, is developed to study the reason of the spectrum difference formation. It is found from the experiment that the decay constant T_(decay) of the time-resolved fluorescence spectrum of the tumor is obviously larger than that of the adjacent normal tissue. And T_(decay) increased with the tumor growth, from 554μs in the first day to 634μs in the eighth day while it keeps steady for normal tissue. The simulated spectrum at different z_1 and different τ reveal that both the increase of z_1 and τ can delay the spectrum decay. It is believed that T_(decay) of the tumor tissue should be larger than that of adjacent normal tissue because of the hypoxia. The changes of tumor size and oxygen status cause the difference of the time-resolved fluorescence spectrum between the tumor and the adjacent normal tissue and this fact can be made use of in the tumor diagnoses.