Measurement of concentration of photosensitizer, tissue oxygen can reveal information about tissue metabolism and
effects of photodynamic therapy (PDT). The purpose of this study is to develop a monitoring and auto-controlling laser
system for PDT instrument. The concentration of issue oxygen is detected by near-infrared spectroscopy (NIRS). The
blood drug level of photosensitizer is monitored during PDT by fluorescence spectroscopy which was induced by 532
nm Laser. The Laser's output power and idle time can be determined by those monitored parameters. Thus, this system
will provide insights into ways to enhance treatment's effectiveness and selectivity in clinical operation.
Tumor oxygen depletion plays an important role in the process of Photodynamic Therapy (PDT). The paper focuses
on the improvement of the lighting mode to carry out this cancer therapy more effectively in low oxygen content. The
effect of interstitial lighting was compared with that of continuous lighting in different oxygen density measured with a
homemade device in PDT. 90 mice were divided into 3 groups: the contrast group, the continuous lighting group and the
interstitial lighting group. The initial oxygen content was measured with a homemade device before the treatment. To
examine the different effects, both the interstitial lighting and the continuous lighting have the same fluent rates
(30mW/cm2, 32.4J/ cm2). The continuous lighting lasted 18 minutes while the interstitial lighting lasted 36 minutes
with 1 second's idle time and 1 second's effective time of each pulse. The result shows that the volume of tumor
doubling duration in interstitial lighting group is longer in the condition of low initial oxygen content. Thus with low
initial oxygen content, the interstitial lighting is more effective than the continuous lighting during PDT.
We present a new method of diagnosing cancer, femtosecond laser in vivo HpD (haematoporphyrin derivatives) two-photon fluorescence, and observations of in vivo HpD two-photon fluorescence of cancer tissue of little mice using excitation of femtosecond laser pulse generated by self-mode-locked Ti:sapphire laser. The narrow pulse width, the high peak power of the excitation source and the central wavelength of 810 nm that is the window wavelength of biological tissue show that biomedical signal induced by this light source must have high signal-noise ratio. This femtosecond laser pulse and the two-photon fluorescence technique do no harm to normal tissue surrounding the cancer. The result of our experiments shows that the cancer tissue can be distinguished and diagnosed with the method of in vivo HpD two-photon fluorescence excited by femtosecond laser pulses with suitable wavelength.
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