Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
  • G02B6/0005—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being of the fibre type
  • G02B6/0006—Coupling light into the fibre
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/42—Coupling light guides with opto-electronic elements
  • G02B6/4298—Coupling light guides with opto-electronic elements coupling with non-coherent light sources and/or radiation detectors, e.g. lamps, incandescent bulbs, scintillation chambers
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
  • A61B18/18—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves
  • A61B2018/1807—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using light other than laser radiation

Definitions

• the present invention relates to a system for use in ⁇ medical applications requiring light having high power
• the present s invention provides a light source which is capable of
• the '172 patent suggests 2 that light can be coupled into a fiber optic via a cone 3 which reduces the spot size. 4 Although the cone shown in the '172 patent will 5 produce a smaller spot size, the beam delivered power will 6 actually be reduced because of the inherent optical 7 properties of the coupling cone and the optical fiber.
• the 1 entrance of cone has an acceptance angle which determines
• the present invention provides a system which utilizes a conventional light source to produce a narrowly focused s beam of radiation having intensity similar to that produced
• the system is broadly comprised of a
• the optical o parameters of the light source and the reflectors are 1 matched to produce a narrowly focused beam of intense 2 radiation.
• the second mirrored surface has an aperture 3 therein which is placed at a point near the second focal 4 point of the first reflector.
• the light source is placed 5 at the first focal point of the reflector and the accepting 6 end of a fiber optic is placed at the second focal point of 7 the reflector.
• the aperture is positioned such that only s rays meeting predetermined geometrical exit criteria can 9 pass through the aperture and be accepted by the fiber 0 optic located at the second focal point. Those rays which i do not meet the exit criteria are reflected by the mirrored 2 surface toward the interior of the cavity.
• Some of the 3 reflected rays provide additional amplification of the 4 light produced by t_.e light sou ;e and the path of these 5 rays is altered such that they are eventually able to meet 6 the exit criteria and pass through the aperture.
• the light produced by the system can be coupled into a fiber optic system for delivery to a target area.
• the dimension of the light source and the focal length of the reflectors in the optical cavity are chosen such that the focused beam can be easily accepted by a fiber optic having a numerical aperture approximately equal to the inverse of two times the "F/number" of the reflector.
• FIG. 1 is an elevational side view of the optical a system of the present invention showing the light source 9 positioned in an optical cavity comprising a first curved ⁇ o reflector and a second reflector.
• FIG. la is an elevational side view of the optical
• FIG. 2 is an illustration of the geometry of the
• FIG. 3 is an elevational side view of the optical
• FIG. 4 is a graphical illustration of a conventional
• FIG. 5 is an elevational view in cross section of the
• FIG. 6 is an illustration of a focussed beam of
• FIG. 7 is a graphical illustration of. the wavelengths ght produced by an arc lamp.
• the 7 reflector 14 which can be either curved or flat.
• Light ⁇ produced by the cavity is carried by a fiber optic 20 to a 9 delivery system 24, discussed in greater detail below.
• the o embodiment of the invention illustrated in FIG. 1 comprises 1 a second reflector 14 which is flat.
• the alternate 2 embodiment of the optical cavity, shown in FIG. la, 3 comprises a curved second reflector 14a.
• the light source 10 used in the present invention is a 5 conventional light source in the form of an arc lamp.
• the 6 arc lamp comprises a cathode 16 and an anode 18 which are 7 connected to an appropriate power source and mounted in a e quartz housing 19.
• the interior of the housing 19 is 9 filled with a gas or vapor which produces light when 0 excited by an electric current flowing between the cathode 1 16 and the anode 18.
• a gas or vapor which produces light when 0 excited by an electric current flowing between the cathode 1 16 and the anode 18.
• the cathode 16 passes 5 electrons which are accelerated toward the anode 18.
• the 6 collision of the electrons with the Xenon or Mercury atoms 7 causes the electrons orbiting those atoms to move to a higher energy levels or "stimulated states.”
• the . excited electrons return to their normal energy levels, they emit photons which have a wavelength determined by the difference between the energy levels of the excited state and the normal state.
• the rays 22a-22b and 22a'-22b' originate at the theoretical center of the first focal point of the reflector 12 are all reflected toward the second focal point of the reflector 12 and can be coupled into the fiber optic 20 after passing through the aperture in the second reflector 14.
• Other rays originate at points between the cathode 16 and anode 18, as illustrated by rays 22c and 22c 1 , respectively. These rays are also reflected by the reflector 12, but fail to pass through the aperture 13 in the second reflector 14 and, therefore, are reflected by the mirrored surface of the reflector 14 back toward the interior of the cavity, as discussed in greater detail below.
• Some rays, such as the one illustrated by reference numeral 22d are not reflected by the first reflector 12 and thus exit the reflector cavity.
• the light rays which are focussed at the second focal point can be accepted by the optical fiber 20, provided certain constraints are met.
• the limiting factors are the size and acceptance angle of the optical fiber, the size of the gap of the light source 10 at the first focal point of the reflector 12 and the magnification of the reflector 12.
• the gap size of the light source is directly correlated with the amount of electromagnetic radiation produced with larger gap sizes producing greater power.
• the size of the gap also has an impact on the ability to converge the light rays for efficient entry into the fiber optic. As discussed above, FIG.
• FIG. 1 includes an illustration of light rays produced from different portions of the gap between the cathode 14 and the anode 16 of the arc lamp used in the preferred embodiment of the invention. Since the rays originate from a band of points, rather than from the theoretical focal point of the reflector, the group of rays focused at the second focal point will also arrive in a band defined by the geometry of the reflector. This geometry of the arriving rays is shown in FIG. 2, which shows a band' of arriving rays passing through the aperture having a width of "D.” In the case where the band width of the rays reflected by the curved reflector 12 and passing through the aperture corresponds to the acceptance angle of the fiber optic, there will be effective coupling into the fiber optic.
• the rays which are returned by the reflector 14 are re-reflected by the first curved reflector 12 will be directed to the interior of the quartz housing of the arc lamp. Upon passing through the quartz, these rays will be refracted slightly. This will change the direction of the rays as illustrated in FIG. la, thus preventing them from being caught in a reflective loop. Moreover, the additional light returned from the reflective surface will add to the new light being generated in the arc gap between which will result in a certain degree of amplification of the light produced by the arc lamp. The amount of amplification is determined by the reflectivity of the reflectors and the absorption characteristics of the various media within the cavity.
• FIG. la is an illustration of an alternate embodiment of the present invention utilizing a curved reflector 14' having a mirrored inner surface.
• the curved reflector 14' includes an aperture 13' passing light rays meeting the acceptance criteria of the acceptance angle of the fiber optic 20. In this embodiment of the system, those rays which meet the exit criteria, e.g. ray 36, of the cavity are allowed to pass through the aperture 13 • . However, those rays, e.g.
• the arc lamp 10 is pulsed to power levels several times higher than normally used for continuous wave (CW) operation of the lamp.
• This pulsed operation has the effect of creating very intense production of light.
• CW continuous wave
• FIG. 3 a small sphere of plasma 15 production is shown at the tip of the cathode 16 of the arc lamp.
• This plasma is caused by very intense bombardment of electrons emerging from the tip of the cathode 18.
• This plasma region normally exists near the tip of the cathode when the lamp is operating in the CW mode.
• the pulsed operation of the lamp will cause the plasma region to temporarily expand to span the entire distance between the electrodes, as illustrated by the plasma region 15* shown 1 in FIG. 3.
• FIG. 4 is a graphical illustration of the power levels
• FIG. 4 is approximately 28 amps, 1000 watts of power
• the current 10 is increased to more than 50 amps for brief periods of ⁇ time, e.g., on the order of 1 to 10 milliseconds, resulting
• 15 lamp is capable of sustaining 100 amps for periods of time
• the pulsed operation of the arc lamp used in the s present invention produces the intense plasma region 9 between the two electrodes, as discussed above, thus making 0 it possible to obtain beam intensities at very small spot i sizes which are very similar to those produced by 2 conventional lasers.
• the 4 curved reflector 12 has an elliptical geometry. However, 5 other geometries known to those skilled in the art can- be 6 used. For example, a parabolic reflector with an 7 appropriate lens system could be used to obtain focussing properties similar to that obtained with v._e elliptical reflector used in the preferred embodiment.
• the magnification of the elliptical reflector 12 is determined by the distance between the focal points and the size of the ellipse.
• the light source 10 is placed at one of the first focal point of the reflector and an optical fiber 20 is placed at a second focal point of the reflector.
• the delivery system of the present invention shown in FIG. 5, is comprised of two lenses configured in a 4-f arrangement.
• the delivery system comprises a housing 40 with an optic terminator 42 secured in one end thereof.
• the terminator delivers light from the fiber optic 20 to a first diverginc lens 44 to produce a collimated light beam.
• the collimated light beam is passed through an appropriate filter 46, discussed in greater detail below, and is received by a converging lens 48 for focussing the light radiation on the tissue to be treated.
• the filter is placed in the light path to control the wavelengths being delivered to the ablation or coagulation site.
• the position of the filter is chosen in the delivery system between the two lenses.
• the ' filtering operation may be chosen by sliding a filter into a slot in the delivery system.
• Two grated index GRIN fiber lenses can replace the normal lenses as presented, as long as both of them have good transmission in the ⁇ V and visible wavelengths.
• a conical tip 50 discussed in greater detail below, assists in the precise delivery of the light to a ⁇ desired location on the tissue.
• the conical tip 50 is used as a guide to indicate the visible wavelengths (due to Chromatic aberrations) .
• FIG. 6 ⁇ o is an illustration of the concentric cones of radiation ⁇ which result from the light being focused by the 4-f lense
• the UV light creates an ablation sight which is
• Typical spectra for Mercury and Xenon lamps are shown in FIG 7.
• the Mercury lamp has several peaks in UV and 0 visible ranges as opposed to the Xenon lamp which has a more 1 continuous spectrum.
• Mercury-Xenon lamps have 2 characteristics very similar to the Mercury with a small 3 additional Xenon baseline.
• the Mercury lamp spectrum peaks at 404, 430, 546 and 5 579 are very close to the peaks of the absorption 6 characteristic of blood.
• Tissue on the other hand, has low 7 absorption characteristic in the visible, increasing in ⁇ excess of 100 cm -1 in the UV wavelengths below 320 nm.
• an Excimer laser is used for tissue cutting, ⁇ the tissue will bleed since the blood vessels are not 9 coagulated to stop the blood flow.
• Blood coagulation could 0 be promoted by using a dye laser tuned at the wavelength of 1 high blood absorption, but with much lower tissue absorption 2 in which the target of coagulation is the blood and not the normal tissue. Consequently, an optimized scalpel may be 4 based on using multiple wavelengths such as UV for cutting 5 and wavelengths around 420, 546 and 577 where the relative 6 blood absorption is higher than other wavelengths.
• the 7 Mercury lamp (or Mercury Xenon lamp) has the proper 8 characteristic to match the needed multi-spectral 9 characteristics as discussed above.
• the system of the present invention can be operated in 1 a pulsed mode, as discussed above, to produce ablation of a 2 site using pulse durations on the order of a few 3 milliseconds.
• the short pulse width results in minimal 4 thermal damage to the tissue.
• the present invention may be used for cutting tissue if 6 all available wavelengths are focussed at the tip of the 7 delivery system. In order to cauterize or coagulate blood. the wavelengths in the visible range and of particular interest the peaks of 546 and 577 nm can be delivered to the tip with other wavelengths being filtered out by inserting an appropriate filter into the delivery system.
• tissue welding Several different wavelengths of lasers from argon (488 and 514 nm) and YAG (1064 nm) and C02 (10,600 nm) have been used for tissue welding.
• the main goal in tissue welding is to heat the junction of the two sections of tissue (held against each other) to reach temperatures just below their coagulation point resulting in melting of the collagen of tissue together.
• the melting of the collagen promotes better and faster tissue healing of the junction.
• the present invention is capable of generating a beam having wavelength components which can penetrate into tissue to depths of several millimeters. Consequently, if the system is configured to operate in a continuous wave mode, rather than pulsed mode, the continuous low level light can produce sufficient heating of tissue to allow the present invention to be used for tissue welding as well.
• a temperature monitoring system can be incorporated in the delivery system to provide more accurate tissue heat generation thereby avoiding over-exposure of the tissue while allowing more homogeneous welding process.
• a cutting device In normal surgery, it is usually important to use a cutting device to penetrate into the tissue or body.
• the present invention can be used to ablate tissue and cut through different layers of skin.
• the delivery system is placed against the ablation site and the light source is activated to produce high power pulses of light.
• the generated light causes tissue ablation and the operator can move the delivery system along the desired cutting pattern on the skin.
• a complete penetration through skin normally requires several passes of tissue removal with a careful inspection of the ablation site.
• the present invention also can be used to cauterize blood quickly.
• the cauterizing filter is place in the optical path and the system is activated while the delivery system is pointed toward the bleeding site.
• This technique can be used to coagulate blood vessels under skin in depths down to 0.6 millimeters as well.
• the system can then be configured to operate in the welding mode whereby a continuous low level light is produced.
• the delivery system produces mild heating of the closed cut area as it is moved along the cut path.
• the rate of movement and the heat generated can be calibrated by either a heat sensing feedback system or the experience of the operator. Normal junction temperatures in the 60-85 °C produces the desired effect. Althougr.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Health & Medical Sciences (AREA)
• Surgery (AREA)
• Life Sciences & Earth Sciences (AREA)
• Heart & Thoracic Surgery (AREA)
• Animal Behavior & Ethology (AREA)
• Engineering & Computer Science (AREA)
• Biomedical Technology (AREA)
• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
• Medical Informatics (AREA)
• Molecular Biology (AREA)
• Otolaryngology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Laser Surgery Devices (AREA)
• Radiation-Therapy Devices (AREA)
• Lasers (AREA)

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• 1992
  • 1992-06-26 KR KR1019930704013A patent/KR100289249B1/ko not_active IP Right Cessation
  • 1992-06-26 JP JP5501700A patent/JPH06511594A/ja active Pending
  • 1992-06-26 EP EP92914434A patent/EP0591404A4/de not_active Withdrawn
  • 1992-06-26 CA CA002112560A patent/CA2112560A1/en not_active Abandoned
  • 1992-06-26 AU AU22551/92A patent/AU673982B2/en not_active Ceased
  • 1992-06-26 WO PCT/US1992/005456 patent/WO1993000551A1/en not_active Application Discontinuation

Non-Patent Citations (2)

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