Surgery – Instruments – Light application
Reexamination Certificate
1999-11-30
2002-06-11
Dvorak, Linda C. M. (Department: 3739)
Surgery
Instruments
Light application
C606S013000, C606S023000, C606S027000, C606S033000, C607S088000, C607S096000
Reexamination Certificate
active
06402739
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the application of energy to biological tissue, and specifically to the application of electromagnetic energy to the skin.
BACKGROUND OF THE INVENTION
It is known in the art to apply electromagnetic energy to biological tissue to engender changes therein. Sunbathers, for example, regularly expose themselves to bright sunlight in order to increase melanocyte activity in the basal layer of the epidermis, responsive to the sun's ultraviolet (UV) radiation. Artificial UV sources have been created to satisfy the desire for a “healthy” looking tan in the winter. Other forms of electromagnetic energy, laser-light in particular, are currently used in a large range of therapeutic and cosmetic procedures, including eye surgery, hair removal, wrinkle removal, and tattoo removal.
PCT publication WO 98/55035, which is incorporated herein by reference, describes methods for minimizing injury to biological tissue surrounding a site exposed to pulses of electromagnetic energy.
U.S. Pat. No. 5,752,949 to Tankovich et al., which is incorporated herein by reference, describes a hair-removal method for placing a contaminant in the skin, using a laser to create explosions to drive the contaminant deep into hair ducts in the skin, and subsequently heating the contaminant to kill biological tissue surrounding the contaminant. The rate of application of energy is controlled to allow cooling of the skin.
U.S. Pat. No. 5,814,040 to Nelson et al., which is also incorporated herein by reference, describes a method for port wine stain removal, including applying a coolant to the skin, and subsequently directing laser radiation below the cooled area.
U.S. Pat. 5,810,801 to Anderson et al., which is also incorporated herein by reference, describes a method for treating wrinkles in the skin, including directing electromagnetic energy to a target region of the skin, while cooling an area above the target region.
SUMMARY OF THE INVENTION
It is an object of some aspects of the present invention to provide improved apparatus and methods for applying energy to a material.
It is another object of some aspects of the present invention to provide improved apparatus and methods for removing heat generated during application of electromagnetic energy to a material.
It is a further object of some aspects of the present invention to provide improved apparatus and methods for removing heat generated during application of electromagnetic energy to biological tissue.
It is still a further object of some aspects of the present invention to provide improved apparatus and methods for decreasing pain during application of electromagnetic energy to biological tissue.
It is yet a further object of some aspects of the present invention to provide improved apparatus and methods for performing medical treatments.
It is also an object of some aspects of the present invention to provide improved apparatus and methods for performing cosmetic treatments.
It is further an object of some aspects of the present invention to provide improved apparatus and methods for enabling a visible wavelength electromagnetic energy source to perform material and tissue removal and modification.
It is yet a further object of some aspects of the present invention to provide methods and apparatus for enabling a visible wavelength low-power electromagnetic energy source to perform material and tissue removal and modification.
It is still a further object of some aspects of the present invention to provide methods and apparatus for enabling a low-power electromagnetic energy source to perform material and tissue removal and modification.
It is also an object of some aspects of the present invention to provide improved methods and apparatus for enabling a low-power electromagnetic energy source to perform tissue removal and modification, substantially without pain, while controlling the amount of damage to remaining tissue.
In preferred embodiments of the present invention, an energy source applies electromagnetic energy to tissue of a subject, preferably so as to ablate a portion thereof. Thereafter, some of the heat generated by the interaction of the energy with the tissue is removed, typically by applying a coolant or a cooling element to the tissue. Removal of the heat immediately following the application of the energy generally reduces the subject's sensation of the heat, and, in particular, reduces any sensation of pain. Moreover, heat removal typically reduces or eliminates collateral injury to tissue surrounding the ablated area. Typically, although not necessarily, the tissue comprises the subject's skin.
It is known in the art to cool tissue prior to or during the application of electromagnetic energy to a subject's skin. U.S. Pat No. 5,814,040 cited above, for example, describes cooling the epidermis prior to heating tissue thereunder, to minimize damage to the cooled tissue. Similarly, U.S. Pat No. 5,810,801 describes cooling a first region of tissue while heating a second region of tissue thermally coupled thereto. These embodiments of the present invention, by contrast, teach that cooling the tissue following the application of electromagnetic energy is generally advantageous. Furthermore, it is believed that very rapid heating of a target area of the skin, substantially unmitigated by any prior cooling thereof, produces therapeutic results that are superior to techniques which cool a mass of tissue and then apply energy to a cooled target area. In particular, it is believed that the prior art methods which describe cooling of an upper tissue layer prior to interaction of electromagnetic energy therewith generally have an adverse effect on modification and/or ablation of tissue in the upper layer. Notably unlike techniques as taught according to preferred embodiments of the present invention, these prior art methods generally are painful in the absence of an administered anesthetic.
In some preferred embodiments of the present invention, the energy source comprises a laser, whose beam is moved in a pattern over a target area of the skin. The pattern is made up of a sequence of passes over the tissue, each pass describing a line or curve over a predetermined portion of the target area. Typically, the pattern is chosen such that each pass is relatively distant from the preceding one, so that it generally does not cause additional heating of tissue indirectly heated by energy from the preceding pass. The temperature of this latter tissue decreases during the succeeding pass, preferably to approximately the same temperature as prior to the preceding pass. In some of these preferred embodiments, the laser energy is applied to the skin in sets of passes, whereby a set of one or more consecutive passes of the laser across the skin is relatively distant from a preceding set of one or more consecutive passes. The pattern is designed as necessary to ablate tissue, but minimize the undesired accumulation of heat in nearby tissue. Preferably, utilization of a beam pattern as described reduces sensations of pain, and also reduces injury of non-targeted tissue. In some of these embodiments, the tissue is actively cooled, preceding and/or following application of the energy thereto.
In some preferred embodiments of the present invention, a cover is placed over the target area, and the electromagnetic energy is applied through a window in the cover. Preferably, the cover enables an operator to maintain an ambient environment over the target area having properties, such as temperature, pressure, and humidity, which are set so as to minimize pain or discomfort during a procedure. Typically, sensors are coupled to the cover in order to determine parameters of the ambient environment and to generate signals responsive thereto. A control unit is preferably coupled to receive the signals and to actuate various devices so as to cause the signals to converge to desired values. The devices may include, for example, heating and cooling elements, pressure and humidity controllers, an
Dvorak Linda C. M.
Farah Ahmed
Price and Gess
Y-Beam Technologies, Inc.
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