Singlet oxygen (1O2) is widely considered as the major cytotoxic species generated during Type-II photochemical reaction of photodynamic therapy (PDT), and its production is crucial for the treatment outcome of PDT. However, it is still a challenging task for direct detection of 1O2 by using an optical system as its extremely weak luminescence at 1270 nm. In previous study, a high-sensitivity optical fiber detection system has been developed to measure the time-resolved 1O2 luminescence spectra. In this study, an optical phantom of skin tissue has been built to simulate the skin optical properties for research in photodynamic therapy (PDT). The phantom consists of an absorber (ink) and a scatterer (Intralipid) and phosphate buffer saline (PBS). Rose Bengal (RB) was utilized as the model photosensitizer to generate 1O2. The time-resolved 1O2 luminescence spectroscopy were measured by using a 1O2 luminescence detection system with a fiber prober in tissue phantom. Furthermore, the effect of absorption coefficient (μa) and scattering coefficient (μs) on the photosensitizer triple state lifetime (τT) and 1O2 luminescence lifetime (τD) was investigated as well. The results indicated that the integrated intensity of 1O2 luminescence decrease with the increase of μa and μs. μa has no significant effect on τT and τD. τT increase with the increase of μs, and it finally stabilized around 1.6 μs. Meanwhile, τD decrease firstly and then increase slowly, and it finally stabilized around 14 μs. This result indicates that this system for 1O2 luminescence have a potential for clinical applications in PDT dosimetry.
Vascular-targeted photodynamic therapy (V-PDT) has been demonstrated to be an effective treatment modality for nonmalignant diseases such as capillary malformations port wine stains (PWS). V-PDT treatment of PWS involves a complex interaction of light, photosensitizer (PS), oxygen and biological tissue. A three-dimensional (3D) model of PWS with a Y-bifurcation blood vessels was proposed for mathematical simulation of the spatial and temporal distribution of singlet oxygen (1O2), which related to the distribution of light, PS and oxygen. A graphics processing units (GPU)-based method, Monte Carlo eXtreme (MCX), was applied to calculate the light deposition in the PWS, and a set of differential equations were utilized to describe the photochemical reactions involved in V-PDT. Using the obtained light energy deposition and the distributions of the PS and oxygen, a dynamic change model of the cumulative concentration of 1O2 ([1O2]) was estimated. The data show that the smaller vessels are more likely to acquire more [1O2].
A digital micromirror device (DMD) based structural illumination and projection optical system were designed and evaluated for fluorescence imaging and diffuse reflectance imaging of tissue in spatial frequency domain, respectively. Light emitting diodes (LEDs) at discrete wavelengths (532, 620, 656 nm) provided illumination for the diffuse reflectance imaging while a 532 nm laser diode (LD) was used as excitation light source of photosensitizer (PS) fluorescence. Both the LEDs and LD light were collimated, homogenized and converged on a DMD to generate the structural illumination. A projection lens was also designed to project a rectangular structural illumination spot on target tissue. The designed optical system could be applied to provide variable frequency structural illumination for depth sensitive excitation of PS and diffuse reflectance imaging.
Characterization of spermatozoon viability is a common test in treating infertility. Recently, it has been shown that label-free, phase-sensitive imaging can provide a valuable alternative for this type of assay. We employ spatial light interference microscopy (SLIM) to perform high-accuracy single-cell phase imaging and decouple the average thickness and refractive index information for the population. This procedure was enabled by quantitative-phase imaging cells on media of two different refractive indices and using a numerical tool to remove the curvature from the cell tails. This way, we achieved ensemble averaging of topography and refractometry of 100 cells in each of the two groups. The results show that the thickness profile of the cell tail goes down to 150 nm and the refractive index can reach values of 1.6 close to the head.
The aim of this case study was to explore the relationship between porphyrins and colon adenocarcinoma, and to examine the potential of porphyrin-induced fluorescence for the diagnosis of colon cancer. Further studies were carried on 8 cases ex vivo colon adenocarcinoma samples which exceptionally exhibited 635 nm fluorescence emission under 405 nm excitation. The time-resolved fluorescence spectra at 635 nm emission under 405 nm excitation were also measured and two-exponential decay fitting was performed to determine the fluorescence lifetime at 635 nm emission. Significant difference was observed between the spectra of normal and cancer tissues, which included an emission peak at 635 nm under the excitation wavelengths of 405 nm. There was also a significant difference between the fluorescence lifetimes of 635 nm emission of the normal tissue and cancer tissue (P<0.05). These results demonstrate that the spectroscopic analysis method allows a selective detection of adenocarcinoma tissues. This spectral profile and lifetime of the red fluorescence resemble that of porphyrins, which suggests that porphyrin fluorescence may be a useful biomarker for characterizing colon cancers of certain patient populations.
This study evaluates the potential of a discriminant analysis to classify colonic mucosa from
autofluorescence spectral characteristics. With 337 nm excitation, the autofluorescence spectra of colonic
tissues were measured using a FLS920 spectrofluorimeter. Principal component analysis (PCA) combined
with Fisher's discriminant analysis was performed for tissue classification. As a result, the sensitivity and
specificity of the discriminant analysis is 92.3% and 90.5%, respectively. The results suggest the relative
concentrations of collagen and nicotinamide adenine dinucleotide (NADH) are the potential diagnostic
biomarkers for colonic tissue classification using autofluorescence spectroscopy, and the discriminant
analysis based on PCA is useful to differentiate adenocarcinoma from normal tissue.
A laser induced fluorescence imaging system for localization of Nasopharyngeal Carcinoma is developed. In this
fluorescence imaging system, the fluorescence intensity with information of detected objection is gained by an image
intensifier, which makes color information of the fluorescence image eliminated and the result is a monochrome image of
the fluorescence with thermally induced noise. The monochrome fluorescence image is sent to a CCD and captured by an
image board, which is controlled by a computer. Image processing is carried out to improve the image quality and
therefore improve the system's ability to differentiate carcinomas from normal tissue. Gaussian smoothing is
implemented in order to reduce the noise. Image binarizing process is realized to obtain an optimal threshold of the
image. Image pixels with grey value below this threshold are assigned as diseased and those above are normal. A pseudo
color processing is then accomplished to get better visual perception and understanding of the image, greatly increasing
the detail resolution of the grey image. The processed image is then displayed on the screen of the computer in real time.
The real time laser induced fluorescence imaging system with the image processing methods developed is efficient for
localization of the nasopharyngeal carcinoma.
A novel wavelength detection and demodulation technique of fiber Bragg gratings sensors is put forward. The principle, experimental setup and results of the sensor are analyzed. The new technique converts detections of shift of center reflecting wavelength into detection of light intensity extremum. Furthermore, a spatial division multiplexing system of Bragg gratings sensors based on the novel technique is developed. The multiplexing numbers are not confined by bandwidth of light source and tunable scope of single fiber Bragg grating.
Both Raman and infrared spectrum measure vibrational transitions in molecules, so they can detect structure and clinical medical character of material in molecule level. Since human blood keeps in close touch with tissue, it may have some symptoms in the blood when functional disorder happens. For this reason, people have already developed a lot of methods to investigate the feasibility of using it to diagnose and therapy, especially in the orientation of non-invasive measurement. In this paper the principles of two kinds of spectra were analyzed and discussed first, involving the advantages and disadvantages in actual research. Then, according to different composition and research direction of human blood, we introduced the research progress of this field at present. Finally the difficulty we met and the expectation in the future are discussed.
The therapeutic effectiveness of laser-electromagnetism combined therapy in chronic prostatitis is studied. Four patients were treated by irradiating the prostate’s correlative parts and acupoints with 650nm semiconductor laser and pulse electromagnetism respectively. Three of them were recovery and only one was ineffective. This demonstrates the feasibility of using laser-combined electromagnetism for assistant treatment on chronic prostatitis. A further study on combined therapy of chronic prostatitis using 810nm, 650nm semiconductor laser and pulse electromagnetic wave is also introduced.
Fourier transform in-infrared and near-infrared Raman spectroscopies were used to study human red cell. The assignment of characteristic groups of human red cell structure was basically confirmed. The intensity of different Raman shift signal has different varying law when the power of laser is changing and it doesn’t satisfy the simple linearity. Laser Raman spectroscopy combining with infrared spectroscopy is an effective method to study the structure of human red cell.
The theoretical spectral response formula of the PIN Gallium phosphorus photodetector is given. At the same time, considering the process requirements, the optimum device structure parameters of GaP photodetector are obtained by numerical calculation and simulation. Under the condition of these structure parameters, the responsivity of the GaP photodetector will be obtained at a given wavelength.
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