The theoretical, design, technological and software aspects of creating a dynamically controlled LED surgical lamp for contrast visualization of biological tissues during surgical operations are considered. The concept of design a surgical lamp, which combines white light illumination and dynamic control colored illumination, is proposed. It allowed both to reach high-quality illumination of the operational field and to improve the contrast of visualization of different biological tissues and objects. An optical system of the lamp, which allows achieving maximum and uniform illumination and provides uniform color mixing all over the operating field, is considered. Surgical lamp used both phosphor-conversion white LEDs for general illumination and monochrome AlInGaN, AlGaInP LEDs for precision control of color illumination. The developed software allows you to independently change the intensity of six spectral LED components: blue (460 nm), cian (505 nm), green (530 nm), lime (550 nm), orange (590 nm) and red (630 nm) to synthesize colored lighting in wide chromaticity scale. Also, within a wide range, it is possible to change the luminance and color temperature of the general illumination from white phosphor LEDs. Color and luminance evels are controlled by pulse-width modulation of the LED current. The light parameters of the surgical lamp are set by remote computer connected to the lamp via Bluetooth. To determine optimum illumination conditions for contrast visualization, optical characteristics of different biological tissues in combination with color LED emission are investigated. As a result, the experiments on animals showed the contrast of biological tissues imaging increases when they were illuminated with specially selected spectra emitted by developed lamp.
The possibility of endovenous laser coagulation using Ti-containing optothermal fiber converters (TOTFC) is discussed. Optical and thermal models have been developed to estimate the distribution of radiation and temperature in the vein during endovenous laser coagulation when using TOTFC for 532 nm, 810 nm, 980 nm, 1064 nm, 1310 nm, 1470 nm, 1910 nm and 2100 nm wavelengths. Radiation intensity distributions around the TOTFC and on the vessel wall were obtained and evaluated. The absorbance efficiency of laser energy with different wavelengths for TOTFC has been calculated. As a result of the thermal calculation, for different wavelengths, average laser power from 8 to 15 W with traction speed from 1 to 7 mm/s, the thermodynamics of the blood vessel wall and TOTFC was determined. During endovenous laser coagulation temperature inside TOTFC exceeds 500°C. The optimal combinations of average laser power and titanium-containing converter traction speed are defined for coagulation of the vein wall.
The possibility of endovenous laser coagulation using C-doped and Ti-doped optothermal fiber converters is discussed. Optical and thermal models have been developed to estimate the distribution of light and temperature in the vein at endovenous laser coagulation using a 980 nm diode laser. It is shown that the distribution of light in the vein when using Ti-doped converter is significantly different from the distribution obtained using C-doped converter and clear quartz fiber. As a result of the thermal calculation, for 980 nm laser power equal to 20 W, the dynamic of blood vessel wall temperature was determined. The effect of blood flow speed (1.5 mm/s) on the temperature of the vein wall was taken to account. It is shown that the blood vessel wall can be heated up to a temperature of 80 °C, which is needed for collapse of the vein, after 21 seconds of laser exposure by C-doped converter and after 43 seconds of laser exposure by Ti-doped converter at endovenous 980 nm laser coagulation of vein with a diameter 5 mm.
It is reported on pilot clinical study of photodynamic therapy (PDT) of onychomycosis with high-intensive LED device with a wavelength of 660±10 nm. The possibilities of achieving a positive result after PDT of onychomycosis using this high-intensive LED device are demonstrated. It was found that the average growth of the novel healthy nail area after PDT is 6.25% per a month.
The effectiveness of the application of the laser fractional treatment to remove scars of the oral mucosa has been investigated. For the first time it has been demonstrated that laser fractional treatment by diode laser radiation with a wavelength of 980 nm, power 7 W and pulse duration 120 ms leads to the disappearance of scar on human oral mucosa.
In the experiment, the reaction of the rat oral mucosa to fractional mechanical and laser treatment performed by radiation of a diode laser with a wavelength of 980 nm in various combinations of the average power of laser radiation, the pulse duration and energy of the laser radiation, along with the fill factor was investigated. Optical and histological examination of the rat oral mucosa during its regeneration after fractional treatment was performed. It was found that on the 5th day after a single-shot fractional laser treatment, the number of mitotically dividing cells exceeds the number of those cells after a single-shot fractional mechanical treatment and in the control area. It has been found that on the 28th day after a three-fold fractional treatment, the surface of the mucosa is visually bleached, and after the laser treatment, the connective tissue of the mucosa lamina propria and the submucosal layer contains fibrous structures and cellular elements, mainly myo- and fibroblasts. It has been found that during the regeneration on the 28th day after a three-fold fractional laser treatment, the thickness of the epithelium and the thickness of the submucosal layer with lamina propria of mucosa increase in comparison with the control.
Optical and histological methods were used to examination of influence the power and pulse duration of 980-nm diode laser to the dimensions and morphology of tissue around fractional micro injuries created by the radiation of that laser in the oral mucosa of rats in vivo. The power of laser radiation (P) varied in the range of 1÷21 W, and its pulse duration (tp) - in the range 50÷500 ms.
Histological examination showed that in the mucosa of the oral cavity after the laser fractional irradiation, there following effects are found: a tissue defect, a transudate in the lumen of ablative micro injury, stretching and compacting effect of the nuclei of the basal epithelium, the disappearance of granules of the keratohialin, destroying the structure of the connective tissue, erythrocyte stasis in the vessels, the disappearance of transverse striation in the muscle fibers in muscle layer.
It has been found that ablative micro injury begins to form up at P = 5 W, tp = 100 ms and affects only the epithelial layer of the mucosa. At P = 7 W, tp = 120 ms, the ratio of width to depth of ablative micro injury is 1 : 1, and at P = 10 W, tp = 100 ms, an ablative micro column with ratio of 1 : 1.5 is formed in the epithelial and submucosal layers of the mucosa. The laser effect with P = 15 W, tp = 200 ms leads to lengthening of the ablation micro-column to 1 : 2, with the bottom of the ablative micro column reaching the muscular layer. With a further growth of laser power or pulse duration, the width of the micro injury increases, and the growth of the micro injury depth is slowed down so that the micro column buildup is ceased.
The results of in vitro study of the soft tissue temperature dynamics during 980 nm diode laser cutting by different types (CLEAR, FILM, VOLUMETRIC) of fiber opto-thermal converters (FOTC) are presented. It was found that the use of CLEAR fiber end (tip) at the laser power below 8.5 W doesn't lead to the soft tissue (chicken meat) destruction. The chicken meat destruction (cutting) begins when irradiated by 8.5 W laser radiation for approximately 9.0 s. At the power of 9.0 W this time decreases up to 7.0 s, at 9.5 W − to 6.0 s, at 10.0 W − to 3.5 s. The moment of soft tissue cutting start correlates with the moment of black layer (absorber) formation at the fiber end and appearance of visually identifiable laser cut walls on the photos; the temperature in this case rapidly increases up to 850 °C. It was determined that the FILM FOTC begins to cut the soft tissue immediately after exposure of laser radiation with power of 4.0 W, the temperature in this case reaches 900 °C. It was determined that the VOLUMETRIC FOTC begins to cut the tissue immediately after exposure at the power of 1.0 W, the temperature in this case reaches 600 °C. VOLUMETRIC FOTC can produce more effective cuts of the soft tissue at the laser power of 4.0 W, in this case, the temperature is above 1200 °C.
Dynamics of temperature signal in operation area and laser power at nevus, papilloma, and keratoma in vivo removal by a 980±10 nm diode laser with "blackened" tip operating in continuous (CW) mode and with temperature feedback (APC) mode are presented. Feedback allows maintaining temperature in the area of laser treatment at a preset level by regulating power of diode laser radiation (automatic power control). Temperature in the area of laser treatment was controlled by measuring the amplitude of thermal radiation, which occurs when tissue is heated by laser radiation. Removal of neoplasm was carried out in CW mode with laser radiation average power of 12.5±0.5 W; mean temperature in the area of laser treatment was 900±10°C for nevus, 800±15°C for papilloma, and 850±20°C for keratoma. The same laser radiation maximal power (12.5 W) and targeted temperature (900°C) were set for nevus removal in APC mode. The results of investigation are real time oscillograms of the laser power and temperature in the area of laser treatment at neoplasms removal in two described above modes. Simultaneously with the measurement of laser power and the temperature in the area of laser treatment video recording of surgeon manipulations was carried out. We discuss the correlation between the power of the laser radiation, the temperature in the area of laser treatment and consistency of surgeon manipulation. It is shown that the method of removal (excision with or without traction, scanning) influences the temperature in the area of laser treatment. It was found, that at removal of nevus with temperature feedback (APC) mode to achieve comparable with CW mode temperature in the area of laser treatment (900±10°C) 20-50% less laser power is required. Consequently, removing these neoplasms in temperature feedback mode can be less traumatic than the removal in CW mode.
Results of nevus, papilloma, dermatofibroma, and basal cell skin cancer in vivo removal by a 980±10 nm diode laser with "blackened" tip operating in continuous (CW) mode and automatic power control (APC) mode are presented. The collateral damage width and width of graze wound area around the collateral damage area were demonstrated. The total damage area width was calculated as sum of collateral damage width and graze wound area width. The mean width of total damage area reached 1.538±0.254 mm for patient group with nevus removing by 980 nm diode laser operating in CW mode, papilloma − 0.586±0.453 mm, dermatofibroma − 1.568±0.437 mm, and basal cell skin cancer − 1.603±0.613 mm. The mean width of total damage area reached 1.201±0.292 mm for patient group with nevus removing by 980 nm diode laser operating in APC mode, papilloma − 0.413±0.418 mm, dermatofibroma − 1.240±0.546 mm, and basal cell skin cancer − 1.204±0.517 mm. It was found that using APC mode decreases the total damage area width at removing of these nosological neoplasms of human skin, and decreases the width of graze wound area at removing of nevus and basal cell skin cancer. At the first time, the dynamic of output laser power and thermal signal during laser removal of nevus in CW and APC mode is presented. It was determined that output laser power during nevus removal for APC mode was 1.6±0.05 W and for CW mode – 14.0±0.1 W. This difference can explain the decrease of the total damage area width and width of graze wound area for APC mode in comparison with CW mode.
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