New design of the excitation light source that can stably generate light with center wavelengths of 450nm, 530nm,
632.8nm and white light for auto-fluorescence(AF) and photodynamic diagnosis(PDD) of cancer in clinics in a single
system is presented in this study. The light source consists of Xenon Lamp (300W), light guide module including
motorize filter wheel equipped with optical filters with corresponding to wavelength bands, servo motor, motorize iris, a
cooling system, power supply and optical transmission part for the output light. The transmission part of the light source
was developed to collimate the light with desired wavelength into input of fiber optic. Output powers are obtained
average 99.91 mW for 450±40 nm, 111.01 mW for 530±10nm, and 78.50 mW for 632.8±10nm.
General application of continuous-wave (CW) laser irradiation modes in photodynamic therapy can cause thermal damage to normal tissues in addition to tumors. A new photodynamic laser therapy system using a pulse irradiation mode was optimized to reduce nonspecific thermal damage. In in vitro tissue specimens, tissue energy deposition rates were measured in three irradiation modes, CW, pulse, and burst-pulse. In addition, methods were tested for reducing variations in laser output and specific wavelength shifts using a thermoelectric cooler and thermistor. The average temperature elevation per 10 J/cm2 was 0.27°C, 0.09°C, and 0.08°C using the three methods, respectively, in pig muscle tissue. Variations in laser output were controlled within ±0.2%, and specific wavelength shift was limited to ±3 nm. Thus, optimization of a photodynamic laser system was achieved using a new pulse irradiation mode and controlled laser output to reduce potential thermal damage during conventional CW-based photodynamic therapy.
This study aims at designing and evaluating light source devices that can stably generate light
with various wavelengths in order to make possible PDD using a photosensitizer and diagnosis
using auto-fluorescence. The light source was a Xenon lamp and filter wheel, composed of an
optical output control through Iris and filters with several wavelength bands. It also makes the
inducement of auto-fluorescence possible because it is designed to generate a wavelength band of
380-420nm, 430-480nm, and 480-560nm. The transmission part of the light source was
developed to enhance the efficiency of light transmission. To evaluate this light source, the
characteristics of light output and wavelength band were verified. To validate the capability of this
device as PDD, the detection of auto-fluorescence using mouse models was performed.
Photodynamic diagnosis (PDD) is a method to diagnose the possibility of cancer,
both by the principle that if a photosensitizer is injected into an organic tissue, it
is accumulated in the tissue of a malignant tumor selectively after a specific
period, and by a comparison of the intensity of the fluorescence of normal tissue
with abnormal tissue after investigating the excitation light of a tissue with
accumulated photosensitizer.
Currently, there are two methods of PDD: The first is a way to acquire incitement
fluorescence by using a photosensitizer, and the second is a way to use auto-fluorescence
by green fluorescence protein (GFP) and red fluorescence protein
(RFP) such as NADH+ active factors within the organic body. Since the selection
of the wavelength band of excitation light has an interrelation with fluorescence
generation according to the selection of a photosensitizer, it plays an important
role in PDD. This study aims at designing and evaluating light source devices that
can stably generate light with various kinds of wavelengths in order to make
possible PDD using a photosensitizer and diagnosis using auto-fluorescence. The
light source was a Xenon lamp and filter wheel, composed of an optical output
control through Iris and filters with several wavelength bands. It also makes the
inducement of auto-fluorescence possible because it is designed to generate a
wavelength band of 380-420nm, 430-480nm, 480-560nm. The transmission part
of the light source was developed to enhance the efficiency of light transmission.
To evaluate this light source, the characteristics of light output and wavelength
band were verified. To validate the capability of this device as PDD, the detection
of auto-fluorescence using mouse models was performed.
In this paper, we optimized the PDT laser system to improve the therapy effects of malignancies. In order to optimizes, the variation of laser output and specific wavelength shift have to reduced. To improved the PDT therapy clincian require the diverse radiation mode which irradiate the tumor surface. Continuous wave mode that general application may causes tissue thermal damage not only to tumor tissue, but also to nomal tissue. Therefore, we suggested new technique for radiation method to improved PDT effects and prevented to the thermal effects for the tissue. In experimental we verified the stability of wavelength, laser output stability and proved the reduced thermal effects to the tissue using the pulse & burst radiation modes in vitro.
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