JPH021500B2 - - Google Patents

Description

Detailed Description of the Invention The present invention generates a second harmonic from a pulsed beam of an Nd:YAG laser, and uses this second harmonic to treat abnormal blood vessels and pigmented nevi such as punctate pigment spots. The present invention relates to a laser irradiation device for treating birthmarks (hereinafter referred to as birthmarks).

BACKGROUND ART Conventionally, a birthmark treatment method using a continuous wave beam of an argon laser has been known. This method is a treatment method that selectively cauterizes and destroys the affected area by irradiating the affected area with a high-power argon laser beam.

However, bruise treatment using a continuous wave beam of an argon laser has the following problems.

(1) Low efficiency The wavelength of argon laser is 5145 Å, but the absorption wavelength of blood, which selectively absorbs the laser beam, has a peak at 5420 Å as shown in Figure 1. It's out of sync. For this reason, the efficiency of argon lasers used for bruise treatment is extremely low.

(2) Damage to normal cells Since a continuous wave beam is used, damage to normal cells due to thermal diffusion is unavoidable.

In order to solve the above problem (1), the present inventors created a glass fiber whose length was set in advance so that a wavelength conversion corresponding to the difference between the laser oscillation wavelength and the wavelength at which absorption occurs in the irradiation target occurred. In Japanese Patent Application Laid-Open No. 2003-2011, the wavelength of an argon laser was converted to a wavelength close to the maximum absorption wavelength of blood by using the argon laser for wavelength exchange of laser light.
No. 56-148360 was proposed. Although this proposal has made it possible to perform efficient treatment, the proposed device requires an extremely high-precision device to convert wavelengths, and is also expensive, making it problematic to use as a practical device. In addition, problem (2), which was resolved by the above proposal, remained unsolved.

In order to solve the above problem, the present inventors first thoroughly investigated a laser device having a conversion wavelength near the maximum absorption wavelength of blood, and found that the second harmonic of the Nd:YAG laser is 5300 Å. They discovered that the wavelength is extremely close to the maximum absorption wavelength of blood, 5420 Å, and that wavelength conversion is easy.
The present invention was achieved by discovering that in order to provide a device that uses the second harmonic of an Nd:YAG laser and does not cause damage to normal cells, a pulsed beam must be used. That is, the present invention provides a Q switch that converts a continuous wave laser beam oscillated by an Nd:YAG laser oscillation device into a repetitive oscillation beam, and a second harmonic that generates a second harmonic from the fundamental wave emitted from the laser oscillation device. a wave generator, a duplexer that separates the fundamental wave and the second harmonic emitted from the second harmonic generator, and a guide that guides the second harmonic separated by the duplexer to the affected area. This is a laser irradiation device for treating bruises, which includes an optical glass fiber and a laser gun attached to the tip of the glass fiber.

The novel idea of the present invention lies in the use of the second harmonic of the Nd:YAG laser, which has a wavelength very close to the maximum absorption wavelength of blood. This idea made it possible to selectively absorb the laser beam into red blood cells, making it possible to perform extremely efficient treatment.

Another novel idea of the present invention is that the affected area is irradiated with a pulsed beam of Nd:YAG laser.
This idea made it possible to prevent thermal damage to normal cells around the affected area.

Next, one embodiment of the device of the present invention will be described with reference to the drawings. Figure 1 is a block diagram of the device of the present invention, which is a Nd:YAG laser oscillation device 1.
and a Q switch 2 that converts the continuous wave laser beam oscillated by this device into a repetitive oscillation beam,
Fundamental wave a with a wavelength of 1.06 mμ emitted from the above device
A second harmonic generator 3, such as KDP, which generates a second harmonic wave b with a wavelength of 5300 Å from the harmonic wave generator 3, and a diffraction device that separates the fundamental wave a and the second harmonic wave b emitted from the harmonic generator 3. A demultiplexer 4 such as a grating or a demultiplexing prism, and a condensing device for condensing the demultiplexed second harmonic wave b and making it efficiently enter the laser beam into the core part of the light guiding glass fiber. Lens 5 and
Glass fiber 6 for guiding the second harmonic to the affected area
and a laser gun 8 housing a lens 7 for adjusting the laser beam emitted from the glass fiber to an appropriate beam diameter. 9 is a holder for fixing the end of the light guide glass fiber.

Such devices use pulsed second harmonic waves emitted from an Nd:YAG laser, the pulse width of which is typically less than 1 microsecond for Q-switches.
For bruising treatment, the smaller the pulse width, the better, usually 5
~100 ns pulses are effective.

FIG. 2 shows an example in which the laser gun 7 constituting the laser irradiation device of the present invention is attached to a traveling device. A moving platform 10 (hereinafter referred to as X-
It is composed of a support table 11 on which the moving table is mounted, and a control device 12 for operating the XY table 10 and laser irradiation. 13 is a remote control switch for remotely controlling the control device. The support stand 11 is a trolley 14
It is composed of a cylindrical vertical shaft 15 fixed to a cylindrical vertical shaft 15, a movable body 16 mounted to be movable up and down along this shaft 15, and a horizontal member 17 held by this movable body 16 so as to be slidable in the front and back direction. The XY table 10 is attached to the front end of the horizontal member 17 via a swinging mechanism 18 in the longitudinal and lateral directions. A pulley 19 is attached to the upper end of the vertical shaft 15, the movable body 16 is attached to one end of a wire 20 suspended from the pulley, and a weight 21 for balance is attached to the other end. It is being 22
is a tightening member that is screwed onto the movable body 16 to fix the movable body in a predetermined position. Horizontal member 1
7 is slidably supported by a bearing provided in the movable body 16 in the thrust direction. The X-Y table 10 includes a Y table 23 movably mounted on a base, a base fixed on the Y table, and an X table movably provided on the base in a direction perpendicular to the Y table. table 24
The X and Y tables move forward and backward and left and right by the rotation of screw rods that receive the rotational force of step motors 25 and 26. This X-Y table can have various known structures. A bracket 27 is fixed to the X table and projects forward, and a laser gun holding member 28 is fixed to the tip of this bracket.
A laser gun 8 is attached to this member.

In the above device, first, the horizontal member 17 constituting the support base 11 is adjusted, and the X-Y table 10 attached to one end of this member is positioned near the affected area S of the patient M on the bed 30 to be treated. Further, after setting the distance between the tip of the laser gun 8 and the affected area S to 5 to 60 mm, treatment is performed by irradiating the affected area with a laser beam by manual or automatic operation.

As described above, the device of the present invention can treat extremely efficiently by using the second harmonic of the Nd:YAG laser, and can completely remove thermal damage to normal skin by irradiating the laser beam in pulses. Furthermore, even if a low-power laser beam is used, the therapeutic effect is equal to or greater than that of a conventional high-power laser beam, making it an extremely useful device in practice.

Example 1 The following experiment was conducted using the second harmonic repetitive oscillation output of a Q-switch Nd:YAG laser device with an output of about 100 mJ.

An artificial birthmark was created by stacking 10 sheets of 50μ thick parchment paper, one side of which was coated with red pigment, with the red colored side facing up. Here, the red pigment surface corresponds to birthmarks (dilated capillaries), and the parchment paper layer corresponds to normal skin.

The wavelength emitted from the above device to this artificial birthmark
Second harmonic wave of 530 mμ and intensity of 107 watt was irradiated 5 times. As a result, the red pigment in the six layers of parchment paper decomposed,
When observed under a microscope with a magnification of 400 times, it was found that there were no traces left. On the other hand, the parchment paper layer was not damaged at all.

The above results indicate that in the treatment of bruises, the pulsed beam effectively destroys and removes only the bruises without damaging normal tissue.

Comparative Example Ten sheets of the same parchment paper as in Example 1 were stacked to form an artificial birthmark, and when this artificial birthmark was irradiated with a continuous laser beam (0.2 seconds, 2.5 watt) from the above device, it appeared in six layers with a diameter of approximately 1.5 mm. A hole opened.

The above results indicate that continuous laser beam damages normal cells.

[Brief explanation of drawings]

Figure 1 is a graph showing the absorption wavelength of blood.
FIG. 2 is a block diagram showing one embodiment of the device of the present invention, and FIG. 3 is a side view showing an example of the laser traveling device. DESCRIPTION OF SYMBOLS 1...Nd:YAG laser oscillation device, 2...Q switch, 3...2nd harmonic generator, 6...Glass fiber for light guide, 8...Laser gun, 10...Moving table.

Claims (1)

[Claims] 1 A Q switch that converts the continuous wave laser beam oscillated by the Nd:YAG laser oscillation device into a repetitive oscillation beam, and a second harmonic generator that generates the second harmonic from the fundamental wave emitted from the laser oscillation device. , a duplexer that separates the fundamental wave and the second harmonic emitted from the second harmonic generator, and a light guide glass that guides the second harmonic separated by the duplexer to the affected area. A laser irradiation device for treating bruises, comprising a fiber and a laser gun attached to the tip of the glass fiber.