WO2001087408A2

WO2001087408A2 - Method and apparatus for applying electromagnetic radiation into human tissues for producing a therapeutic effect

Info

Publication number: WO2001087408A2
Application number: PCT/IL2001/000429
Authority: WO
Inventors: Oleg Badaev; Shlomo Bidas
Original assignee: Ib Soft Ltd.
Priority date: 2000-05-19
Filing date: 2001-05-15
Publication date: 2001-11-22
Also published as: AU2001256642A1; WO2001087408A3; IL152814A0; IL161757A0

Abstract

Methods and systems for applying electromagnetic energy to human tissues include a flash lamp and a cooling system for cooling a flash lamp (304). The cooling system includes a tubular element (306, 406) made of material through which a continuous flow of a coolant passes. The flash lamp resides within the tube and the tube is made of a material that is transparent to the light produced by the lamp. The tube material filters the harmful UV specter and passes the desiresd specter. A reflector (502) reflects light produced by the lamp and also resides within the tube. The methods of the present invention include the supply of electrical power to the flash lamp. Power is supplied to the lamp as a series of short, low power impulses that eliminate the overheating of a tissue being treated.

Description

METHOD AND APPARATUS FOR APPLYING

ELECTROMAGNETIC RADIATION INTO HUMAN TISSUES

FOR PRODUCING A THERAPEUTIC EFFECT

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to devices and methods that use electromagnetic energy to produce therapeutic effects.

Description of Related Art Usage of both coherent (laser) and non-coherent (flash lamps and laser diodes) impulse sources of electromagnetic energy in the range of wavelengths of 500-1500 nm and over has found wide application in therapeutic practice and especially in cosmetology. Examples of such application include applying electromagnetic radiation into human tissues to produce coagulation of micro and small blood vessels, removal of various pigmentation spots, and depilation.

Nevertheless, present methods of application of electromagnetic energy to human tissues in order to produce a therapeutic effect all suffer an essential shortcoming, namely, high specific power of the impulse (Po). When using lasers, the Po may range from 1,000,000 to 100,000,000 Watt/sq.cm. When using flash lamps and laser diodes, the Po may range from 1 ,000 to 100,000 Watt/sq.cm. Such high powers lead to explosion-like processes in human tissues and to undesirable side-effects, such as burns. Due to the thermo-resistance of the tissue, the speed with which the energy (the heat) spreads becomes relatively slow (around 3 mm / sec). In order to obtain and preserve a desired temperature (e.g., 70-80°C) during the time necessary for therapeutic processes to take effect, the amount of energy that must be applied often leads to such negative consequences as tissue burns, etc.

Taking into account that coagulation of blood-vessels and the destruction of the proteins that constitute follicles does not happen instantaneously, but instead takes some time, it is required that the rated density of the energy would substantially increase. This leads to carbonization of the tissues, which absorb the applied energy. Further, it also leads to warming-up of the surrounding tissues to fairly high and hardly bearable temperatures. Forming the spectrum of the light source causes a significant complication in implementations of practical flash-lamp devices: 60-65% of the radiation is ultra violet (UV), which needs to be filtered out. When using traditional filters, a large amount of energy gets dispersed during radiation. This leads to overheating, and thus, to the loss of spectral characteristics of the filter. A reflector used with the lamp or light source also overheats, which leads to the additional overheating of the entire electromagnetic radiation device.

Recent methods of decreasing the negative consequences of tissue overheating include the preliminary cooling of the treated surface. One method is to apply various gels or anesthetic creams, such as EMLA, etc. While all of the current methods make these procedures less painful, they do not deal with the cause of the pain, which is large amount of applied energy.

FIG. 1 shows the graph 100 of the temperature change after treatment with the

existing methods. The area limited by the 80°C line 102 (τ active laser time and τ active flash lamp time) shows the necessary and the sufficient amount of energy required for the therapeutic effect to occur. The graph 100 also shows how much extraneous energy gets into tissues when the existing methods are applied.

Temperatures corresponding to the laser are indicated by numeral 102, while those corresponding to a flash lamp are indicated by numeral 104. Calculations show that up to 70% of the energy, applied to tissues with the existing methods, is extraneous and harmful for the tissues. In light of the foregoing, there is a need in the art to improve the methods and systems for the application of electromagnetic energy to human tissues in order to produce therapeutic effects. SUMMARY AND OBJECTS OF THE INVENTION

Methods and systems for applying electromagnetic energy to human tissues are disclosed. Specifically, such systems include a system for cooling a flash lamp that includes a tubular element made of material through which a continuous flow of distilled water passes. The flash lamp resides within the tube. The tube is made of a material that is transparent to the light produced by the lamp, but that filters the harmful UV specter. The spectral characteristics of the filter are chosen in such a way that it passes only red and lower infrared light (650 - I200nm). A first reflector for reflecting light produced by the lamp also resides within the tube.

Methods of the present invention include the supply of electrical power to the flash lamp. Power is supplied to the lamp as a series of short, low power impulses that result in the elimination of the overheating of a tissue being treated.

It is an object of the present invention to reduce and/or eliminate the overheating of human tissue produced by its exposure to therapeutic electromagnetic radiation.

It is another object of the present invention to efficiently cool down the flash lamp and its corresponding reflector used for irradiating electromagnetic energy of the lamp in order to reduce the overheating of the human tissue. It is another object of the invention to control the supply of power to the flash lamp in order to reduce the overheating of the human tissue. With these and other objects, advantages and features of the invention that may become hereinafter apparent, the nature of the invention may be more clearly understood by reference to the following detailed description of the invention, the appended claims and to the several drawings attached herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiments of this invention will be described in detail, with reference to the following figures, wherein:

FIG. 1 illustrates a graph showing the change in temperature of human tissue when a conventional laser or a conventional flash lamp is used; FIG. 2 illustrates a graph showing the change in temperature of human tissue resulting from the use of the systems and methods of the present invention;

FIG. 3 illustrates the use of an elliptical prism in accordance with one embodiment of the present invention;

FIG. 4 illustrates a tube used for cooling the flash lamp in accordance with one embodiment of the present invention;

FIG. 5 illustrates the placement of a first reflector inside the cooling system in accordance with two embodiments of the present invention;

FIGS. 6A and 6B illustrate a series or pulses produced by a power supply used to energize the flash lamp;

FIG. 7 illustrates a first power supply in accordance with one embodiment of the present invention;

FIG. 8 illustrates a second power supply in accordance with one embodiment of the present invention;

FIG. 9A illustrates the placement of a second reflector inside the cooling system in accordance with one embodiment of the present invention; and

FIG. 9B is a sectional view of the placement of a second reflector inside the cooling system in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION FIG. 2 shows the graph 200 of the temperature change after applying any of the disclosed methods. The graph 200 shows that the tissue temperature 202 resulting from the applied energy is only a little bit more than the temperature required (80°) in order to get the therapeutic effect. The temperatures of both the tissues absorbing the energy and of the tissues surrounding the treated surface are substantially lowered. The rated power of the impulse Po, when applying the present method, is 5 to 100 Watt/sq.cm, which cannot damage human tissues.

FIG. 3 illustrates one embodiment of the cooling system 300. The system 300 includes an elliptical prism 302, a tube 306, and a flash lamp 304.

The prism 302, while illustrated as having an elliptical shape, may assume other shapes such as rectangular, conic, etc. The prism 302 is optically transparent for a desired part of the specter. For example, in order to allow radiation from 650nm to 1200nm, the elliptical prism may be made of red pyrex.

The source of electromagnetic energy of the present invention can be the flash lamp 304. The flash lamp 304 is a conventional flash lamp filled with Krypton under pressure (e.g., 8 kg/sq.cm.) to allow the increase of output energy in a desired part of the specter. The specific density of the current flowing through the flash lamp is about 100-

500 A/sq.cm.

The flash lamp 304 is positioned coaxially inside the tube 306. The tube 306 is

made of a transparent or colored glass and may act as a filter of the light emitted by the

flash lamp 304. If the tube is used as a filter then the prism may be transparent. The

construction of the tube 306 allows a liquid to flow within the walls comprising the tube 306.

Because of the filtering capabilities of the tube 306, the tube can be used to form a

specter as required by a specific radiation procedure. For example, the tube 306 may

disperse up to 70% of the energy radiated by the flash lamp 304. Any energy surplus on

the tube produced by that dispersion is absorbed by a liquid continuously flowing through the tube. The flowing liquid is preferably a coolant, such as distilled water.

The cooling tube 306 and the prism 302 form an integral unit. That is, the flash

lamp 304 and the tube 306 are coaxially positioned inside the elliptical prism 302. The

prism 302 is also cooled by the liquid that flows through the tube 306.

Alternatively, a system 400 (FIG. 4) for obtaining a desired spectrum (e.g., 650-

1200nm) includes a tube 406 with a section 410 designed for attaching a prism thereto.

In the particular example illustrated in FIG. 4, the shape of section 410 is rectangular.

Nevertheless, the section 410 allows the attachment of prisms of various geometries (see the rectangular prism 402 and the trapezoidal prism 408) and also allows their quick replacement. The section 410 may be made of the same material that the prism is made of.

The flash lamp 304 is located coaxially inside the tube 406. A coolant flows through the tube 406, cooling the lamp 304 and the attached prism. The tube 406 may

also filter the light produced by the flash lamp 304.

The desired shape of the prism may depend on the size of the tissue area to be

treated. The light emitted by the flash lamp 304 passes through section 410 and through

the attached prism (e.g., 402 or 408) and is then projected on the area to be treated.

FIG. 5 illustrates the placement of a reflector inside the cooling system in

accordance with two embodiments of the present invention. FIG. 5 illustrates a side view

of each of the two embodiments. The reflector 502 is placed inside the tube 406 for an embodiment that includes the use of the rectangular prism 402. The reflector is

preferably made of gold in order to resist corrosion and to make the system more

efficient, since gold reflects red and lower infrared light. Alternatively, the reflector can

be covered with galvanic gold.

Like the flash lamp 304, which may be used with any of the embodiments of the

present invention, the reflector 502 may be used with the second embodiment in FIG. 5. The second embodiment includes the use of an elliptical prism 302. The reflector 502 is placed inside the tube in the vicinity of the flash lamp 304 and

in contact with the coolant, which also resides inside the tube. The placement of the

reflector solves the problem of surplus heat, since the reflector is in contact with the coolant. FIGS. 6A and 6B illustrate a series of pulses produced by a power supply used to drive the flash lamp. The method of the present invention includes the supply of power to the flash lamp 304. In essence, power is supplied to the flash lamp as a sequence of short, low power impulses. This results in the application of electromagnetic energy to the tissue such that the overheating of the tissue is avoided while the temperature and duration of the energy application are sufficient to produce a therapeutic effect (e.g., the coagulation of protein).

For example, when energy is applied to a tissue, the coagulation time of proteins in the tissue upon application of the energy is estimated to be in between 0.1 and 2 seconds. Thus, in attempting to coagulate proteins, energy is applied to the tissue for that period of time. To apply energy to the tissue, the flash lamp 304 is supplied with power for a period of time in between 0.1 and 2 seconds (see numeral 601). The power is supplied as a series of pulses, the pulse frequency being set in between 10 to 200 Hz (see numeral 603). Finally, the impulse ratio may range in between .01 and 1 (see numeral 605). The impulse ratio is defined as the pulse width divided by the pulse period. The power density of a single pulse illustrated in FIG. 6A is in the range from about 0.01 to 0.5 J/sq.- cm. In order to produce the required temperature of 75-80 degrees Celsius, the total energy applied to the tissues corresponding to a series of impulses is in the range from about .05 to 15 J/sq.-cm.

For a deeper penetration of energy in the tissues, power is supplied to the flash lamp 304 as shown in FIG. 6B. Specifically, a continuous series of impulses 61 1 can be supplied for a period ranging from 0.1 to 2 seconds. That continuous series of impulses 61 1 may be repeated a number of times (e.g., five times as shown), with a repetition period of 0.3 to 1.5 seconds. The aforementioned schemes allow the increase of energy application time to up to 4 seconds without causing overheating of the skin. Further, the application of energy on the tissues by use of those schemes produces the desired therapeutic effect.

The flash lamp 304 is thus uniquely used, so that the feeding impulse voltage is a little bit higher than the simmer mode voltage. For a flash lamp with arc length 50 mm, the impulse voltage lies within the limits of 60-140 volts, which, together with the high krypton pressure, allows maximization of spectrum radiation in the red zone. In the method of the present invention, the flash lamp 304 may wait for the incoming impulse in the simmer mode and turns off automatically after 5 minutes. During ignition of the flash lamp 304 in the simmer mode, an automatic calibration of the electromagnetic source (e.g., lamp and prism) takes place. Adjustment of the flash lamp energy is performed through the change of the initial voltage of the flash lamp power source or through addition of an impulse to the main impulse series.

Performance of these steps, in addition to the low voltage of the power source, increases the life cycle of the flash lamp 304 while preserve the required energy level. For example, the number of impulses supplied to the flash lamp 304 before its replacement may reach 10,000,000. This allows the use of the same flash lamp for 5-6 years.

The flash lamp power source may be constructed by storing energy in low-voltage capacitors 701 (60-140 volts) and transmitting it directly to the flash lamp through a MOSFET transistor or a PFN 703 (FIG. 7). Alternatively, as depicted in FIG.8 the flash lamp power source can be constructed by storing energy in high-voltage capacitors 801 (300-500 volts) and transmitting the energy through an impulse transformer 803 (output voltage 60-140 volts) to the flash lamp by means of an impulse power source, controlled by a computer (not shown). For higher energies (around 3000-5000 J and higher) it is more advisable to use the second method (FIG. 8). For lower energies (500-2500 J), the first method (FIG. 7) is preferable.

When the MOSFET transistor or the PFN becomes out of order, the first method avoids large outputs of energy, which can damage the patient. When the voltage on the capacitors gets lower than the voltage of the simmer mode during an emergency impulse, the flash lamp turns off automatically. It is possible to calculate the capacity of the capacitors in such a way that in any case the maximum energy of the flash lamp is below a dangerous limit.

FIG. 9A illustrates the placement of a second reflector inside the cooling system while FIG. 9B is a sectional view of FIG. 9A. The cooling system comprises an external rectangular casing 901 made of a heat-conducting material, e.g., a metal. Within the casing 901, a space 905 is provided for deploying therein the cooling tube 906.

A second reflector 907 is provided, which is situated beneath the tube 906 and surrounds the tube 906 from below. Through the open upper part of the casing 901, a prism 402 is inserted and secured on the attachment section of the cooling tube 906.

Beneath the second reflector 907 and in vicinity thereto, a through-going channel 903 is made in the casing. By virtue of the coolant continuously flowing through this channel 903, an additional means for cooling is provided, and thus the second reflector 907,_.positioned adjacent to the channel 903, is efficiently cooled. The prism 402 is cooled as well, since its bottom part contacts metallic walls of the casing.

While this invention has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications and variations are apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention as set forth above are intended to be illustrative and not limiting. Various changes may be made without departing from the spirit and scope of the invention.

Claims

CLAIMSWhat is claimed is:

1. An apparatus for applying electromagnetic radiation into human tissues to produce therapeutic effect, said apparatus comprising a flash lamp (304) for producing the electromagnetic radiation, a prism (302,402) for refracting the said radiation and directing it to the human tissues and a system for cooling the lamp, said system for cooling comprising: a tubular element (306, 406) surrounding the flash lamp and capable to pass the electromagnetic radiation, produced by the lamp, wherein the prism is attached to the tubular element and a liquid flowing through the tubular element for cooling down the flash lamp.

2. The apparatus of claim 1 , further comprising: a reflector (502) for reflecting the radiation produced by the flash lamp, the reflector residing within the tubular element.

3. The apparatus of claim 1 , wherein the tubular element (306, 406) is made of a translucent material and filters the radiation produced by the flash lamp.

4. The apparatus of claim 1, wherein the prism (302, 402) is made of red pyrex.

5. The apparatus of claim 1 , wherein the tubular element (306, 406) has a section to which the prism is attached.

6. The apparatus of claim 1 , wherein the liquid is a coolant.

7. The apparatus of claim 2, wherein the reflector is in contact with the liquid.

8. An apparatus for applying electromagnetic radiation into human tissues to produce therapeutic effect, said apparatus comprising a flash lamp (304) for producing the electromagnetic radiation, a casing (901 ) made of heat-conducting material, the casing having three openings; a tubular element (906) surrounding the flash lamp, the tubular element being insertable through a first opening of the casing; a prism (402) refracting light produced by the flash lamp that passes through the tubular element, the prism attaching to the tubular element when inserted through a second opening of the casing; a first liquid flowing through the tubular element for cooling down the flash lamp; a first reflector (502) reflecting the light produced by the flash lamp, the first reflector residing within the tubular element; a second reflector (907) reflecting the light produced by the flash lamp, the second reflector positioned beneath the tubular element and adjacent to a third opening of the casing; and a second liquid flowing through the third opening for cooling down the second reflector.

9. A method of energizing a flash lamp comprising: connecting a power source to the flash lamp; and controlling the power source to transmit, for a period of time in between 0.1 and 2.0 seconds, a series of pulses having a frequency in between 10 and 200Hz; wherein each pulse has an impulse ratio ranging in between 0.01 and 1, and a power density in between 0.01 and 0.05 J/cm².

10. A method of energizing a flash lamp comprising: connecting a power source to the flash lamp; and controlling the power source to transmit a continuous series of pulses; wherein the continuous series is re-transmitted with a repetition period ranging from 0.3 seconds to 1.5 seconds, and each pulse in the continuous series of pulses has an impulse ratio ranging in between 0.01 and 1, and a power density in between 0.01 and 0.05 J/cm².