64.
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
τ, 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 μs, respectively. And
T
s increased with the tumor growth, from 554 μs in the first day to 634 μs 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 overgrouth. This fact could be of use in the tumor diagnoses.
相似文献