The difference in time-resolved fluorescence spectrum between the cortical
sarcoma and the adjacent normal tissue was studied in both experimental and theoretical ways. The Clinical data were obtained in vivo using a time-resolved fluorescence spectrometer employing a single fiber-optic probe for excitation and detection. Tissue was modeled as s-180
sarcoma tumor surrounded with normal muscle and was mediated by the
Palladium-
porphyrin photosensitizer (Pd-
TCPP). The emitted fluorescence was considered as arising from the
tumor tissue or the normal muscle, due to the presence of the
photosensitizer. A computational code which could simulating time-resolved fluorescence emission was presented and applied to comparing fluorescence decay of
photosensitizer in different stages of
tumor growth. In this code the different stages of the
tumor was modeled through changing the time tau, the delay of the fluorescence photon emission and
z (max), the thickness of the
tumor. It was found in the in vivo experiment that the fluorescence from
tumor tissue decayed more quickly than from the adjacent normal muscle. For the ten rats in the first experiment day, the mean decay constant of
tumor T (s) and normal tissue T (n) were 554 and 526 mus, respectively. And T (s) increased with the
tumor growth, from 554 mus in the first day to 634 mus in the eighth day while T (s) kept steady. It was believed that the more adequate
oxygen supplied by the normal tissue can more effectively quench the fluorescence and in the normal tissue the
photosensitizer lifetime is smaller. As a result the simulated time-resolved fluorescence spectrum of normal tissue showed more quickly decay. And the thickness of the
tumor can also delay the fluorescence decay. Both the experimental and simulated results indicated that the germination of the
tumor would increase the decay constant of the time-resolved fluorescence spectrum. So decay constant of the
tumor tissue spectrum should be larger than that of adjacent normal tissue for the reason of
hypoxia and overgrowth. This fact could be of use in the
tumor diagnoses.