U.S. patent application number 11/599786 was filed with the patent office on 2007-03-29 for method and apparatus for emr treatment.
This patent application is currently assigned to PALOMAR MEDICAL TECHNOLOGIES, INC.. Invention is credited to Gregory B. Altshuler, R. Rox Anderson, Sergey B. Biruchinsky, Andrei V. Erofeev, Dieter Manstein.
Application Number | 20070073308 11/599786 |
Document ID | / |
Family ID | 22982411 |
Filed Date | 2007-03-29 |
United States Patent
Application |
20070073308 |
Kind Code |
A1 |
Anderson; R. Rox ; et
al. |
March 29, 2007 |
Method and apparatus for EMR treatment
Abstract
A method and apparatus are provided for performing a therapeutic
treatment on a patient's skin by concentrating applied radiation of
at least one selected wavelength at a plurality of selected,
three-dimensionally located, treatment portions, which treatment
portions are within non-treatment portions. The ratio of treatment
portions to the total volume may vary from 0.1% to 90%, but is
preferably less than 50%. Various techniques, including wavelength,
may be utilized to control the depth to which radiation is
concentrated and suitable optical systems may be provided to
concentrate applied radiation in parallel or in series for selected
combinations of one or more treatment portions.
Inventors: |
Anderson; R. Rox; (Boston,
MA) ; Altshuler; Gregory B.; (Lincoln, MA) ;
Manstein; Dieter; (Boston, MA) ; Biruchinsky; Sergey
B.; (St. Petersburg, RU) ; Erofeev; Andrei V.;
(North Andover, MA) |
Correspondence
Address: |
NUTTER MCCLENNEN & FISH LLP
WORLD TRADE CENTER WEST
155 SEAPORT BOULEVARD
BOSTON
MA
02210-2604
US
|
Assignee: |
PALOMAR MEDICAL TECHNOLOGIES,
INC.
Burlington
MA
THE GENERAL HOSPITAL CORPORATION d/b/a MASSACHUSETTS GENERAL
HOSPITAL
Boston
MA
|
Family ID: |
22982411 |
Appl. No.: |
11/599786 |
Filed: |
November 15, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11235697 |
Sep 21, 2005 |
|
|
|
11599786 |
Nov 15, 2006 |
|
|
|
10033302 |
Dec 27, 2001 |
6997923 |
|
|
11235697 |
Sep 21, 2005 |
|
|
|
60258855 |
Dec 28, 2000 |
|
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Current U.S.
Class: |
606/96 |
Current CPC
Class: |
A61N 7/02 20130101; A61B
2018/00904 20130101; A61B 2018/00452 20130101; A61B 2018/00458
20130101; A61B 18/20 20130101; A61B 18/203 20130101; A61B
2018/00476 20130101 |
Class at
Publication: |
606/096 |
International
Class: |
A61B 17/60 20060101
A61B017/60; A61B 17/58 20060101 A61B017/58; A61F 2/00 20060101
A61F002/00 |
Claims
1. A method of treating a subject's skin comprising applying energy
to the skin so as to generate a plurality of treatment portions
within a volume of the skin such that each treatment portion is
separated from another treatment portion by an untreated portion of
the volume.
2. The method of claim 1, wherein said step of applying energy
comprises applying acoustic energy.
3. The method of claim 2, wherein said step of applying acoustic
energy comprises focusing the acoustic energy onto said treatment
portions.
4. The method of claim 1, wherein said treatment portions comprise
a fraction of the volume in the range of about 1% to about 90%.
5. The method of claim 1, wherein said treatment portions comprise
a fraction of the volume in the range of about 1% to about 50%.
6. The method of claim 1, wherein said treatment portions comprise
a fraction of the volume in the range of about 10% to about
30%.
7. The method of claim 1, wherein said treatment portions extend
from skin surface to a depth below the surface of the patient's
skin.
8. The method of claim 1, wherein said treatment portions are one
of cylinders, spheres, ellipsoids, solid rectangles or planes.
9. The method of claim 1, wherein said treatment portions are
spaced lines of selected length and thickness.
10. The method of claim 1, wherein said volume of the skin is
pre-cooled to a selected temperature for a selected duration.
11. The method of claim 1, further comprising pre-cooling said skin
volume to at least one depth below the skin surface.
12. A method for treating a patient's skin comprising applying
energy to the skin so as to generate a plurality of periodically
located three dimensional treatment portions within a volume of the
skin such that each treatment portion is separated from another
treatment portion by an untreated portion of the skin.
13. The method of claim 12, wherein said step of applying energy
comprises applying acoustic energy.
14. The method of claim 13, wherein said step of applying acoustic
energy comprises applying the energy to create sub-dermal islands
of damage.
15. The method of claim 13, further comprising applying the
acoustic energy to said treatment portions in a temporal
sequence.
16. Apparatus for treating the skin, comprising a source capable of
generating energy, and a system capable of focusing the energy
generated by the source to a plurality of three dimensional
treatment portions within a volume of skin such that each treatment
portion is separated from another treatment portion by an untreated
portion of the volume.
17. The apparatus of claim 16, wherein the energy is acoustic
energy.
18. The apparatus of claim 16, wherein the system for concentrating
the acoustic energy comprises of at least one phase array.
Description
RELATED APPLICATIONS
[0001] The present application is a continuation of U.S. patent
application Ser. No. 11/235,697, filed Sep. 21, 2005, which is a
continuation of U.S. patent application Ser. No. 10/033,302 (U.S.
Pat. No. 6,997,923) entitled "Method and Apparatus for EMR
Treatment," which was filed on Dec. 27, 2001, and herein
incorporated by reference, which, in turn, claims priority from
provisional application Ser. No. 60/258,855 filed Dec. 28, 2000.
All content disclosed in these applications is hereby incorporated
by reference in its entirety.
FIELD OF THE INVENTION
[0002] This invention relates to methods and apparatus for using
electromagnetic radiation (EMR) for various therapeutic treatments
and more particularly to methods and apparatus for dermatological
treatment by use of spatially confined and concentrated EMR to
create areas of treatment or damage substantially surrounded by
areas of sparing.
BACKGROUND OF THE INVENTION
[0003] Various forms of electromagnetic radiation, particularly
optical radiation, both coherent and non-coherent, have been
utilized for many years for a variety of medical treatments, and in
particular for dermatology treatments. Such treatments include, but
are by no means limited to, removal of unwanted hair, skin
rejuvenation, removal of vascular lesions, acne treatment,
treatment of cellulite, pigmented lesions and psoriasis, tattoo
removal, treatment of skin and other cancers, etc. Most of these
treatments have involved in one way or another the use of a process
known as selective photothermolysis (See for example Anderson R R,
Parrish J., Selective photothermolysis: Precise microsurgery by
selective absorption of the pulsed radiation. Science 1983; 220:
524-526), this process involving irradiating a target area to be
treated with radiation at a wavelength preferentially absorbed by a
chromophore, either a natural chromophore or artificially
introduced chromophore, in the target area, the heating of the
chromophore either directly or indirectly effecting the desired
treatment.
[0004] While these techniques are useful for many of the indicated
applications, these techniques have a number of significant
limitations. First, treatments which are performed over a
relatively large area, such as skin rejuvenation and hair removal,
particularly skin rejuvenation, can cause varying degrees of skin
damage over a substantial treatment area. In particular, such
treatments can sometimes result in a detachment of skin layers.
These relatively large areas of skin damage can frequently take
several weeks or more to heal, and follow-up treatments can
normally not be performed during this period. It would be
preferable if these procedures could be performed in a manner which
would result in smaller, spaced areas of damage which heal more
quickly, this enhancing both patient comfort and the ability to
more quickly perform follow-up treatments. Further, many
treatments, such as for example hair removal and wrinkle removal,
only require that the treatment be performed in small portions or
regions of a much larger treatment area; however, current
techniques of treatment generally require that the treatment be
performed over the entire treatment area rather than in only the
selected regions of the treatment area requiring treatment.
[0005] Another potential problem is the need for a chromophore in
the target area which selectively absorbs the applied radiation to
generate the heat required for treatment. First, to the extent the
regions above the treatment area contain a chromophore which
preferentially absorbs or otherwise absorbs the applied radiation,
such chromophores are also heated, and care must be exercised in
any treatment to assure that such heating does not result in
epidermal or dermal damage. Various forms of cooling of such
overlying regions, sometimes aggressive cooling, are frequently
required to permit such treatments to be performed without damage
to the overlying skin. For example, for hair removal or other
treatments where melanin is targeted, heating of melanin in the
epidermis, particularly at the dermis-epidermis (DE) junction, is a
problem. Where the chromophore being targeted is water,
substantially all tissue in the treatment area and thereabove will
be absorbing the radiation and will be heated, making controlled
treatment of a selected body component difficult, and increasing
the likelihood of unwanted peripheral damaged.
[0006] Another problem with selective photothermolysis is that the
wavelength selected for the radiation is generally dictated by the
absorption characteristics of the chromophore utilized. However,
such wavelengths may not be optimal for other purposes. For
example, skin is a scattering medium, but such scattering is far
more pronounced at some wavelengths than at others. Unfortunately,
wavelengths preferentially absorbed by for example melanin, a
frequently used chromophore, are also wavelengths at which
substantial scattering occurs. This is also true for the
wavelengths typically utilized for treating vascular lesions.
Photon absorption in skin also varies over the optical wavelength
band, wavelengths dictated by selective photothermolysis frequently
being wavelengths at which skin is highly absorbent. The fact that
wavelengths typically utilized for selective photothernolysis are
highly scattered and/or highly absorbed limits the ability to
selectively target body components, and in particular, limits the
depths at which treatments can be effectively and efficiently
performed. Further, the fact that much of the energy applied to a
target region is either scattered and does not reach the body
component undergoing treatment, or is absorbed in overlying or
surrounding tissue to cause undesired and potentially dangerous
heating of such tissue, results in optical dermatology treatments
being relatively inefficient. This low efficiency for such
treatments means that larger and more powerful EMR sources are
required in order to achieve a desired therapeutic result and that
additional cost and energy must be utilized to mitigate the effects
of this undesired heating by surface cooling or other suitable
techniques. Heat management for the more powerful EMR source is
also a problem, generally requiring expensive and bulky water
circulation or other heat management mechanisms. Further, since
chromophore concentration in a target (for example melanin in the
hair) varies significantly from target to target and from patient
to patient, it is difficult to determine optimum, or even proper
parameters for effective treatment of a given target using
selective photothermolysis. High absorption by certain types of
skin, for example dark skinned individuals or people with very
tanned skin, often makes certain treatments difficult, or even
impossible, to safely perform. A technique which permitted all
types and pigmentations of skin to be safely treated, preferably
with little or no pain, and preferably using substantially the same
parameters, is therefore desirable.
[0007] Still another problem with existing treatment is that the
amount of energy which can be applied to the treatment area, even
where damage to the epidermis, skin scarring or other damage is not
an issue, is frequently limited by pain experienced by the patient.
Ideally, EMR dermatology procedures, which are typically for
cosmetic purposes, should be painless or substantially painless.
While if the procedure is being performed by a physician, pain may
be controlled by the use of a local anesthetic, or even by putting
the patient to sleep, there are risks in the use of any anesthetic,
and the use of needles to administer a local anesthetic is
undesirable for cosmetic procedures. It would therefore be
preferable if patient pain could be substantially reduced or
eliminated without the need for such procedures, while still
permitting sufficient radiation to be applied to achieve a desired
therapeutic result.
[0008] There are also occasions where microsurgery is required or
desired on a patient's skin, particularly near the skin surface,
where the area to be treated is of a size in the micron range, for
example 10 microns, a size which cannot be treated with a scalpel.
Existing EMR devices for performing microsurgery are also not
adapted for performing surgery on such small targets. A need
therefore exists for improved techniques for performing such fine
microsurgery.
[0009] Further, while EMR techniques are available for treating
some of the conditions indicated above, such techniques do not
currently exist for treating scars, including acne scars, chicken
pox scars and the like, for bumps in the skin resulting from scar
tissue, for stretch marks, for treating certain parasites, etc.. An
effective technique for treating such conditions is therefore
needed.
[0010] Still another problem is in the removal of tattoos or
pigmented lesions, particularly close to the skin surface, where
existing techniques frequently result in blistering and other skin
problems. An improved technique which would permit the fading of
such tattoos or pigmented lesions and/or the ultimate removal
thereof in a gentle enough manner so as to not cause damage to the
patient's skin or significant patient discomfort is also desirable.
Similar techniques for treating various skin blemishes are also
desirable.
[0011] Finally, while techniques currently exist which are
relatively effective in treating large vascular lesions, such
techniques are not as efficient in treating spider veins and other
small veins. Similar inefficiencies exist where radiation is
applied over a relatively large area of a patient's skin where
treatment is required in only relatively small portions of such
area.
[0012] A need therefore exists for an improved method and apparatus
for EMR therapeutic treatments, and in particular for optical
dermatology treatments, which permit more selective treatment in
target areas, and which do not rely on selective photothermolysis
so that the wavelengths utilized may be selected so as to be more
efficient for delivery of radiation to a desired target volume at a
selected depth, and in particular to selected portions of such a
target volume, which portions are preferably surrounded by portions
which are not treated, and so that proper parameters for treating a
given target may be more easily determined.
SUMMARY OF THE INVENTION
[0013] In accordance with the above, this invention provides a
method and apparatus for performing a treatment on a volume located
at area and depth coordinants of a patient's skin, the method
involving providing a radiation source and applying radiation from
the source to an optical system which concentrates the radiation to
at least one depth within the depth coordinants of the volume and
to selected areas within the area coordinants of the volume, the at
least one depth and the selected areas defining three-dimensional
treatment portions in the volume within untreated portions of the
volume. The apparatus has the radiation source and an optical
system to which radiation from the source is applied, the optical
system concentrating the radiation to at least one depth in the
volume and to selected areas of the volume, the at least one depth
and the areas defining the three-dimensional treatment portions in
the volume within untreated portions of the volume. For both the
method and apparatus, the ratio of the treatment portions to the
volume may be between 0.1% and 90%, but is preferably between 10%
and 50%, and more preferably between 10% and 30%. In each instance,
the treatment portions may be cylinders, spheres, ellipsoids, solid
rectangles or planes of at least one selected size and thickness.
The treatment portions may also be spaced lines of a selected
length and thickness. The optical system may either apply radiation
to all the treatment portions substantially simultaneously or the
optical system may apply radiation to at least selected treatment
portions sequentially.
[0014] The patient's skin over at least one treatment portion may
also be pre-cooled to a selected temperature for a selected
duration, the selected temperature and duration for pre-cooling
preferably being sufficient to cool the skin to at least a selected
temperature below normal body temperature to at least the at least
one depth for the treatment portions. For selected embodiments, the
skin is cooled to at least the selected temperature to a depth
below the at least one depth for the treatment portions so that the
at least one treatment portion is substantially surrounded by
cooled skin. The cooling may continue during the applying of
radiation, and for this embodiment, the duration of the applying of
radiation may be greater than the thermal relaxation time of the
treatment portions. The wavelength for the radiation source is
preferably selected so as not to be either highly absorbed or
scattered in the patient's skin above the volume on which treatment
is to be performed. For deeper depth coordinants, the optical
system focuses to a selected depth below the at least one depth of
the treatment portions in order to achieve concentration at the
desired depth coordinant in the patient's skin. A selected
condition in the volume on which treatment is being performed
and/or the patient's skin above this volume may be detected, the
results of the detecting being utilized during the applying of
radiation to control the treatment portions to which radiation is
concentrated.
[0015] The applied radiation preferably has an output wavelength
which is at least in part a function of the at least one depth of
the treatment portions. More specifically, the wavelength of the
applied radiation may be selected as a function of the applied
radiation as follows: depth=0.05 to 0.2 mm, wavelength=400-1880 nm
& 2050-2350 nm, with 800-1850 nm & 2100-2300 nm preferred;
depth=0.2 to 0.3mm, wavelength=500-1880 nm & 2050-2350 nm, with
800-1850 nm & 2150-2300 nm preferred; depth=0.3 to 0.5 mm,
wavelength=600-1380 nm & 1520-1850 nm & 2150-2260 nm, with
900-1300 nm & 1550-1820 nm & 2150-2250 nm preferred;
depth=0.5 to 1.0 mm, wavelength=600-1370 nm & 1600-1820 nm,
with 900-1250 nm & 1650-1750 nm preferred; depth=1.0 to 2.0 mm,
wavelength=670-1350 nm & 1650-1780 nm, with 900-1230 nm
preferred; depth=2.0 to 5.0 mm, wavelength=800-1300 nm, with
1050-1220 nm preferred.
[0016] The method and apparatus may also be utilized to treat a
variety of medical conditions. Where a vascular lesion at a
selected depth is being treated, treatment parameters, including
the optical system and the wavelength of the applied radiation are
selected so that the at least one depth of the treatment portions
are at the depth of the vessel being treated. Similarly, where the
treatment is skin remodulation by treatment of collagen or hair
removal, treatment parameters, including the optical system and the
radiation wavelength are selected so that the at least one depth is
the depth of interdermal collagen and the depth of at least one of
the bulge and matrix of the hair follicle, respectively. The
teachings of this invention may also be used to treat acne, to
target and destroy pockets of fat, to treat cellulite, for tattoo
removal, for treating pigmented lesions, for treating hypotropic
and other scars and other skin blemishes, and for treating various
other conditions in the skin.
[0017] The optical system utilized in practicing this invention may
include an array of optical elements to at least a plurality of
which radiation from the source is simultaneously applied, each of
the optical elements concentrating the radiation to a selected
portion of the volume. Each of the optical elements may for example
focus or concentrate to a line of selected length and thickness,
the lines for some of the elements being at a selected angle to the
lines of other of the elements. The optical system may
alternatively include apparatus for scanning radiation applied to
optical concentrating components so as to successively focus
radiation to N of the treatment portions at a time, where
N.gtoreq.1. The optical system may instead include adjustable depth
optical focusing components, and a positioning mechanism for such
optical focusing components which moves the components to focus at
successive treatment portions. The apparatus may also include a
mechanism which cools the part of the patient's skin at least over
the selected area coordinants to a selected temperature, and
controls which selectively operate the cooling mechanism to
pre-cool this part of the patient's skin for a selected duration
before application of radiation and/or during application of
radiation. The cooling mechanism and the controls may pre-cool the
skin to a temperature and for a duration sufficient to cool the
part of the skin to at least a selected temperature below normal
body temperature to the at least one depth of the treatment
portions or may cool to a depth below the at least one depth of the
treatment portions, the treatment portions in the latter case being
substantially surrounded by cooled skin. The apparatus may also
include a detector for at least one selected condition in the
volume and/or in a part of the patient's skin above the volume and
the optical system may operate in response to the detector to
control the treatment portion of the volume to which radiation is
concentrated.
[0018] The invention also includes a method and apparatus for
performing a treatment on a volume located at an area and depth
coordinant of a patient's skin which includes providing a radiation
source and pre-cooling the patient's skin over at least part of the
area coordinant of the volume to a selected temperature for a
selected duration, the selected temperature and duration being
sufficient to cool the skin to a depth below the depth coordinant
of the volume; and applying radiation to an optical system which
concentrates the radiation to at least one depth coordinant and to
selected areas within the area coordinants to define treatment
portions in the volume, the treatment portions being less than the
total volume and each treatment portion being within untreated
portions and being substantially surrounded by cooled skin. More
specifically, a mechanism may be provided which cools the patient's
skin over the area coordinant to the selected temperature and
controls may be provided for selectively operating the cooling
mechanism to pre-cool the skin for a selected duration before
application of radiation and/or during application of radiation,
the mechanism and controls cooling to a temperature and for a
duration sufficient to cool the skin to at least a selected
temperature below normal body temperature to at least a depth below
the depth coordinant of the volume. The cooling of the patient's
skin by the cooling mechanism may continue during the step of
applying radiation and the duration of radiation application may be
greater than the thermal relaxation time of each treatment
portion.
[0019] Finally, the invention includes a method and apparatus for
performing a therapeutic treatment on a patient's skin by
concentrating applied radiation of at least one selected wavelength
at a plurality of selected three-dimensionally located treatment
portions, which treatment portions are within non-treatment
portions.
[0020] The foregoing and other objects, features and advantages of
the invention will be apparent from the following more particular
description of various embodiments of the invention as illustrated
in the accompanying drawings, the same or related reference
numerals being used for common elements in the various figures.
IN THE DRAWINGS
[0021] FIGS. 1-1B are top views of three optical systems involving
arrays of optical elements suitable for use in delivering radiation
in parallel to a plurality of target portions.
[0022] FIGS. 2-3C are side views of various lens arrays suitable
for delivering radiation in parallel to a plurality of target
portions.
[0023] FIGS. 4-4C are side views of Fresnel lens arrays suitable
for delivering radiation in parallel to a plurality of target
portions.
[0024] FIGS. 5-5B are side views of holographic lens arrays
suitable for use in delivering radiation in parallel to a plurality
of target portions.
[0025] FIGS. 6-6A are side views of gradient lens arrays suitable
for use in delivering radiation in parallel to a plurality of
target portions.
[0026] FIGS. 7-7B are top views of various matrix arrays of
cylindrical lenses, some of which are suitable for providing a line
focus for a plurality of target portions.
[0027] FIGS. 8-8C are cross-sectional or side views of one layer of
a matrix cylindrical lens system suitable for delivering radiation
in parallel to a plurality of target portions.
[0028] FIGS. 9-9B are a perspective view and cross-sectional side
views, respectively, of a two layer cylindrical lens array suitable
for delivering radiation in parallel to a plurality of target
portions.
[0029] FIGS. 10-13 are side views of various optical objective
arrays suitable for use in concentrating radiation to one or more
target portions.
[0030] FIGS. 14-19 are side views of various deflector systems
suitable for use with the arrays of FIGS. 10-13 to move to
successive target portions.
[0031] FIGS. 20 and 21 are side views of two different variable
focus optical system suitable for use in practicing the teachings
of this invention.
[0032] FIGS. 22A and 22B are semi-schematic perspective and side
views respectively of a section of a patient's skin and of
equipment positioned thereon for practicing the teachings of this
invention.
DETAILED DESCRIPTION
[0033] Referring first to FIGS. 22A and 22B, a portion of a
patient's skin 200 is shown, which portion includes an epidermis
202 overlying a dermis 204, the junction of the epidermis and
dermis being referred to as the dermis-epidermis (DE) junction 206.
Also shown is a treatment volume V located at a depth d in the
patient's skin and having an area A. Treatment volume V may contain
one or more vascular lesions which are to be destroyed or removed,
may contain a plurality of hair follicles which are to be either
permanently destroyed, or at least be damaged so as to result in
temporary hair loss, or which are to be stimulated to cause hair
growth, may contain in the area below the DE junction collagen
which is to be restructured by various means, for example by being
temporarily destroyed to stimulate regrowth, particularly for skin
rejuvenation and wrinkle removal, may contain a melanoma to be
removed, a vascular lesion, pigmented lesion, port wine stain,
psoriasis, scar, or other skin blemish or a tattoo to be removed,
or some other bodily component on which optical dermatology
procedures are performed.
[0034] Also shown is a system 208 for delivering optical radiation
to volume V. System 208 includes an EMR source 210, which source
may be a coherent light source, such as a solid-state laser, dye
laser, diode laser, fiber laser or other coherent light source, or
may be an incoherent light source, for example a flash lamp,
halogen lamp, light bulb or other incoherent light source used to
deliver optical radiation in dermatology procedures. Acoustic, RF
or other EMF sources may also be employed in suitable applications.
The output from source 210 is applied to an optical system 212,
which is preferably in the form of a deliver head in contact with
the surface of the patient's skin as shown in FIG. 22B. Where an
acoustic, RF or other non-optical EMR source is used as source 210,
system 212 would be a suitable system for concentrating or focusing
such EMR, for example a phased array, and the term "optical system"
should be interpreted, where appropriate, to include such
system.
[0035] Various embodiments of an optical system 212 are discussed
hereinafter and shown in the various figures. Generally, system 212
functions to receive radiation from source 210 and to
focus/concentrate such radiation to a focused one or more beams 222
directed to a selected one or more treatment or target portions 214
of volume V, the focus being both to the depth d and spatially in
the area A. The energy of the applied EMR is thus concentrated to
deliver more energy to target portions 214. Depending on system
parameters, portions 214 may be cylinders of selected diameter and
thickness, spheres or ellipsoids, and for one embodiment may have a
square or rectangular cross-section. The portions of each shape may
extend through volume V or may be formed in a single layer or
staggered layers thereof. Target portions 214 may also be (a)
relatively narrow strips which may either extend through volume V,
be formed in a single thin layer in volume V or be in staggered
layers of the volume; or (b) may be one or more thin layers formed
in volume V. As will be discussed in greater detail hereinafter,
optical system 212 may focus to all or a selected subset of
portions 214 simultaneously, may contain some type of optical or
mechanical-optical scanner for moving radiation focused to depth d
to successive portions 214, or may generate an output focused to
depth d and be physically moved on the skin surface over volume V,
either manually or by a suitable two-dimensional or
three-dimensional (including depth) positioning mechanism, to
direct radiation to desired successive portions 214. For the two
later embodiments, the movement may be directly from portion to
portion to be focused on or the movement may be in a standard
pattern, for example a grid pattern, with the EMR source being
fired only when over a desired portion 214.
[0036] A cooling element 215 is also included to cool the surface
of skin 200 over treatment volume V. As shown in FIG. 22A and 22B,
cooling element 215 acts on optical system 212 to cool the portion
of this system in contact with the patient's skin, and thus the
portion of the patient's skin in contact with such element. Cooling
element 215 may for example be a thermoelectric element, or may be
a system for passing water, preferably chilled water, a gas,
preferably a chilled gas, and possibly even a cryogenic gas, over
such portion of the optical system. Other techniques for cooling
the surface of the patient's skin known in the art could also be
used. Further, where optical system 212 is not in contact with the
patient's skin, cryogenic spray cooling, gas flow or other
non-contact cooling techniques may be utilized. A cooling gel on
the skin surface might also be utilized, either in addition to or
instead of, one of the cooling techniques indicated above.
[0037] System 208 also includes an optional detector 216, which may
for example be a CCD camera or other suitable detector for a
selected characteristic of the patient's skin. The output from
detector 216 is applied to a control 218, which is typically a
suitably programmed microprocessor, but may be special purpose
hardware or a hybrid of hardware and software. Control 218 controls
both the turning on and turning off of source 210 and may also
control the power profile of the radiation. Control 218 is also
applied to optical system 212 to for example control focus depth
for the optical system and to control the portion or portions 214
to which radiation is being focused/concentrated at any given time,
for example by controlling scanning by the optical system and/or
the beam radiating therefrom. Finally, controls 218 are applied to
cooling element 215 to control both the skin temperature above the
volume V and the cooling duration, both for precooling and during
an irradiation. TABLE-US-00001 TABLE 1 Depth of damage, Wavelength
range, .mu.m NA range Pulse .mu.m broad preferred broad preferred
width range, s 50-200 400-1880 & 800-1850 & <3 0.2-1
<2 2050-2350 2100-2300 200-300 500-1880 & 800-1850 &
<3 0.2-1 <10 2050-2350 2150-2300 300-500 600-1380 &
900-1300 & <2 0.2-1 <60 1520-1850 & 1550-1820 &
2150-2260 2150-2250 500-1000 600-1370 & 900-1250 & <2
0.2-0.6 <120 1600-1820 1650-1750 1000-2000 670-1350 &
900-1230 <1.5 0.2-0.6 <120 1650-1780 2000-5000 800-1300
1050-1220 <1 0.2-0.4 <300
[0038] TABLE-US-00002 TABLE 2 Depth of Diameter of damage, damage,
Wavelength Pulse Focusing .mu.m .mu.m .mu.m NA width, ms Energy, J
depth, .mu.m 300 50-100 2.2 0.3-0.5 <10 >0.00015 400-600 300
50-100 1.7 0.3-0.5 <10 >0.0007 400-600 300 50-100 1.3 0.3-0.5
<10 >0.003 400-600 300 50-100 1.54 0.3-0.5 <10 >0.0003
400-600 300 50-100 1.208 0.4-1 <10 >0.016 400-600 300 50-200
0.92 0.4-1 <10 >0.15 400-600 1000 50-200 1.7 0.3-0.4 <100
>0.01 1100-2000 1000 50-200 1.54 0.4 <100 >0.008 1100-2000
1000 50-200 1.3 0.4 <100 >0.1 1100-2000 1000 50-200 1.208 0.4
<100 >0.4 1100-2000
[0039] TABLE-US-00003 TABLE 3 Diameter Depth of of Pulse damage,
damage, Wavelength, width, Focusing .mu.m .mu.m .mu.m NA ms Power,
W depth, .mu.m 500-1000 200-1000 2.2 0.3-0.5 >100 >0.5
600-1500 500-1000 200-1000 1.7 0.3-0.5 >100 >1.5 600-2000
500-1000 200-1000 1.208 0.3-0.6 >3000 >1.0 600-2000 500-1000
400-1200 0.92 0.3-0.6 >3000 >25.0 600-2000 2000-3500
1000-2000 1.208 0.3-0.4 >10000 >1.5 4000-6000
[0040] In accordance with the teachings of this invention, system
208 controls a variety of parameters of the applied radiation. Data
in Tables 1-3 were found based on Monte-Carlo modeling of photon
propagation in the skin using standard parameters of skin
scattering and absorption for different wavelength. These
parameters include, but are by no means limited to:
[0041] 1. The shape of treatment portions 214. Each of these
portions may be a thin disk as shown, may be an elongated cylinder
which may for example extend from a first depth closer to DE
junction 206 to a second deeper depth or, as will be discussed
later in conjunction with various optical systems to be described,
may be a line focus, each of the lines having a selected length,
width and orientation and adjacent lines being spaced by a selected
amount. The orientation of the lines for the portions 214 in a
given application need not all be the same, and some of the lines
may, for example, be at right angles to other lines (see for
example FIGS. 7A and 7B). Lines can by oriented around a treatment
target for greater efficacy. For example the lines can be
perpendicular to a vessel or parallel to a wrinkle. Portions 214
may also be spherical, ellipsoidal and at least for one embodiment,
may be a solid square or rectangle of selected thickness. The shape
of portion 214 is dictated by the combined parameters of the
focused optical signal applied thereto, with the duration of
application and to a lesser extent the wavelength of the signal
being significant factors in determining the shape of the targeted
portions. For example, it has been found that with a 1720 nm laser
operating at roughly 0.5 J to 2 J and having a pulse duration of
0.5 to 2 ms, a generally cylindrically shaped portion 214 is
obtained. Conversely, with a 1250 nm laser operating in the same
energy range and having a pulse duration of 0.5 to 3 seconds, with
an average of 1 second, generally spherically-shaped target
portions are obtained. The parameters for obtaining a particular
portion shape may be determined in a variety of ways, including
empirically. By suitable control of wavelength, focusing, spot size
at the surface and other parameters, the portions 214, regardless
of shape, may extend through volume V, may be formed in a single
thin layer of volume V or may be staggered so that, for example,
adjacent portions 214 are in different thin layers of volume V. The
pattern of the target portions in volume V may also vary with
application. Further, target portions 214 may also be (a)
relatively narrow stripes which may either extend through volume V,
be formed in a single thin layer or be staggered in different thin
layers, with for example adjacent stripes being in different
layers; or (b) may be one or more thin layers formed in volume V.
While all of the prior configurations for target portion 214 could
be formed either serially or in parallel, the last configuration
with multiple thin layers in the volume V would probably need to be
formed serially. The geometry of portions 214 controls the thermal
damage in the treatment portion. Since a sphere provides the
greatest gradient, and is thus the most spatially confined, it
provides the most localized biological damage, and may therefore be
the preferred target shape for applications where this is
desirable.
[0042] 2. The size of the treatment portions 214. For a depth of
approximately 1 mm into the patient's skin, the minimum diameter of
a portion 214, or the minimum width of a line 214, is estimated to
be approximately 100 microns; however, much larger portions,
several mm's or more, are possible. For greater depths, the minimum
sizes will be greater.
[0043] 3. Center to center spacing between portions 214. The center
to center spacing is determined by a number of factors, including
the size of portions 214 and the treatment being performed.
Generally, it is desired that the spacing between adjacent portions
214 be sufficient to protect the patient's skin and facilitate
healing of damage thereto, while still permitting the desired
therapeutic effect to be achieved. In one application, as little as
4% of the volume V was damaged (i.e. a 4% fill factor); however,
the damaged portions 214 would typically cover substantially more
of treatment volume V. While theoretically, the ratio of the
combined volume of treatment portions 214 to the volume V ( also
sometimes referred to as the fill factor) could be 0.1% to 90%, a
preferred range for fill factor is 10% to 50% for some applications
and 10% to 30% for most applications. It is important that there be
at least some area of sparing around each of the islands or areas
of treatment/damage 214 and that this area of sparing be sufficient
to permit the skin to recover, such recovery being facilitated by
melanosome migration..
[0044] 4. The depth d for the volume V. While it may be difficult
to achieve a small focal spot 214 at a depth much below 1 mm in a
scattering medium such as skin, focussing at depths of up to 4 mm,
and perhaps even more, may be possible so long as a tight focus is
not required and a larger portion size 214, perhaps several
millimeters, is acceptable.
[0045] 5. Focus Depth. While as may be seen from Table 1, depth d
for volume V and the focal depth of optical system 212 are
substantially the same when focussing to shallow depths, it is
generally necessary in a scattering medium such as skin to focus to
a greater depth, sometimes a substantially greater depth, in order
to achieve a focus at a deeper depth d. The reason for this is that
scattering prevents a tight focus from being achieved and results
in the minimum spot size, and thus maximum energy concentration,
for the focused beam being at a depth substantially above that at
which the beam is focussed. The focus depth can be selected to
achieve a minimum spot size at the desired depth d based on the
known characteristics of the skin.
[0046] 6. Wavelength. Both scattering and absorption are wavelength
dependent. Therefore, while for shallow depths a fairly wide band
of wavelengths can be utilized while still achieving a focused
beam, the deeper the focus depth, the more scattering and
absorption become factors, and the narrower the band of wavelengths
available at which a reasonable focus can be achieved. Table 1
indicates preferred wavelength bands for various depths, although
acceptable, but less than optimal, results may be possible outside
these bands.
[0047] 7. Pulse Width. Normally the pulse width of the applied
radiation should be less than the thermal relaxation time (TRT) of
each of the targeted portions 214, since a longer duration will
result in heat migrating beyond the boundaries of these portions.
Since the portions 214 will generally be relatively small, pulse
durations will also be relatively short as indicated in Table 1.
However, as depth increases, and the spot sizes thus also increase,
maximum pulse width or duration also increase. Again, the values
given in Table 1 are maximum values for a given spot size and
shorter pulses may be used. Generally, thermal diffusion theory
indicates that pulse width T for a spherical island should be
.tau.<500 D.sup.2/24 and the pulse width for a cylindrical
island with a diameter D is .tau.<50 D.sup.2/16. Further, the
pulsewidths can sometimes be longer than the thermal relaxation
time of the target portion 214 if density of the targets is not too
high, so that the combined heat from the target areas at any point
outside these area is well below the damage threshold for tissue at
such point. Also, as will be discussed later, with a suitable
cooling regimen, the above limitation may not apply, and pulse
durations in excess of the thermal relaxation time for a damage
portion 214, sometimes substantially in excess of TRT, may be
utilized.
[0048] 8. Power. The required power from the radiation source
depends on the desired therapeutic effect, increasing with
increasing depth and cooling and with decreasing absorption due to
wavelength. The power also decreases with increasing pulse
width.
[0049] 9. Cooling. Typically cooler 215 is activated before source
210 to precool the patient's skin to a selected temperature below
normal skin temperature, for example 0 to 10.degree. C., to a depth
of at least DE junction 206, and preferably to depth d to protect
the entire skin region 220 above volume V. However, in accordance
with the teachings of this invention, if precooling extends for a
period sufficient for the patient's skin to be cooled to a depth
below the volume V, and in particular if cooling continues after
the application of radiation begins, then heating will occur only
in the radiated portions 214, each of which portions will be
surrounded by cooled skin. Therefore, even if the duration of the
applied radiation exceeds TRT for portions 214, heat from these
portions will be contained and thermal damage will not occur beyond
these portions. Further, while nerves may be stimulated in portions
214, the cooling of these nerves outside of portions 214 will, in
addition to permitting tight control of damage volume, also block
pain signals from being transmitted to the brain, thus permitting
treatments to be effected with greater patient comfort, and in
particular permitting radiation doses to be applied to effect a
desired treatment which might not otherwise be possible because of
the resulting pain experienced by the patient. This cooling regimen
is an important feature of the applicants invention.
[0050] 10. Numerical Aperture. Numerical aperture is a function of
the angle .theta. for the focused radiation beam 222 from optical
device 212. It is preferable that this number, and thus the angle
.theta., be as large as possible so that the energy at portions 214
in volume V where radiation is concentrated is substantially
greater than that at other points in volume V (and in region 220),
thereby minimizing damage to tissue in region 220, and in portions
of volume V other than portions 214, while still achieving the
desired therapeutic effect in the portions 214 of volume V. Higher
numerical aperture of the beam increases safety of epidermis, but
it is limited by scattering and absorption of higher angel optical
rays. As can be seen from Table 1, the possible numerical aperture
decreases as the focus depth increases.
[0051] Thus, by judicious selection of the various parameters
indicated above and others, one or more focused radiation beams 222
may be achieved to create islands of treatment/damage 214 in a
treatment volume V at a selected depth d in the patient's skin.
Preferred ranges of parameters for achieving these objectives at
various depths are provided in Table 1. Table 2 and Table 3
illustrate ranges of parameters at various depths for short pulses
(i.e., pulses of less than 10 ms for superficial small targets and
less than 100 ms for deeper depths) and for long pulses
respectively. The values in Table 2 assume that deep cooling
through volume V as described above is not being provided so that
the pulse duration is limited by the thermal relaxation time of
damage portions 214. Thus, at shorter depths, where smaller spot or
focus areas can be achieved, for example a spot having a diameter
of 50 .mu.m, as assumed in Table 2, pulse widths of less than 10 ms
are required and other parameters are selected accordingly.
Conversely, for deeper depths, tight focus cannot be achieved
because of scattering, resulting in a significantly larger diameter
for damage portions 214, and thus a larger thermal relaxation time
for these portions. Therefore, substantially longer pulse widths
can be provided, permitting required energy to achieve the
therapeutic effect to be provided over a longer time interval. This
facilitates removal of heat from region 220, and in particular from
the epidermal portion 202 thereof and from DE junction 206. It also
permits a lower peak power source 210 to be utilized. From Table 2,
3 it is also noted that the focus depth is indicated as greater
than the depth d of the damage portions 214. The reasons for this
have been discussed above.
[0052] While controls 218 can be preprogrammed to focus on selected
portions 214 in target volume V, another option is to use feedback,
either mechanically obtained by use of detector 216, or obtained by
an operator, generally optically, but possibly using other of the
operator senses such as touch or hearing, to control the portions
214 in volume V which are focused on. Assuming, for example, that
detector 216 is a CCD imaging device, the location of hair
follicles, vascular lesions, or other targeted components in volume
V can be located and focused beams 222 specifically directed to the
locations of such components. Thus, assuming a hair removal
treatment, detector 216 could locate each hair follicle at the
surface above volume V, and then focus a beam 222 to each such
follicle at a selected depth, for example, a depth of 1 mm where
stem cells are located. The beam could also be focused to an
extended depth along the follicle, for example, 0.7-3 mm to assure
destruction of all elements within the follicle required for
permanent or substantially permanent hair removal, for example,
destruction of follicle stem cells, without substantially damaging
dermal tissue surrounding the follicle or damage to the follicle
matrix. This result is most easily achieved if the cooling
technique discussed above is utilized, with cooling extending below
the treatment volume V so that each follicle being treated is
surrounded by cooled dermal tissue.
[0053] Feedback could also be used to track a blood vessel or other
vascular structure being treated or to track a wrinkle or wrinkles
to be treated by collagen restructuring. Further, while focused
beams 222 can be automatically positioned in response to outputs
from detector 216 by control 218, such feedback can also be
achieved by the operator manually adjusting the position of optical
system 212 to track and treat hair follicles, vascular structures,
wrinkles or the like.
[0054] More specifically, the scanner used could include three low
power laser diodes, preferably of different colors, used for
detection and one high power laser diode used for treatment. The
scanner can, for example, be utilized both to detect the location
of the blood vessel and the depth of the blood vessel. One of the
three diodes used for detection may be a high power diode which can
be operated in either a detection or treatment mode and detection,
in some instances, may be performed by only one or two diodes,
which diode or diodes may be also used for treatment in some cases.
A suitable scanner can be used to move the detectors and/or
treatment diode over a selected pattern. However, while galvanic
scanners have been used in the past, a contact scanner is required
for this application, since the desired focusing of the beam
requires contact, something which is not possible with a galvanic
scanner. Again, the scanner can be programmed to trace a particular
pattern to locate targets, and may be programmed to follow a target
once located, for example a vein, or the scan may be manually
controlled. Where the scan is following a selected target, for
example a blood vessel, irradiation may occur at selected points
along the blood vessel. It is generally necessary to coagulate a
blood vessel at a selected one or more points along the vessel in
order to stop blood flow therein and kill the vessel. It should not
be necessary to irradiate the entire vessel in order to effect
destruction thereof.
[0055] Where a scanner is being used, the area scanned can be
projected on a screen, providing effective magnification, which
facilitates either the selection of desired target points in a
programmed scan or the performance of a scan along a desired target
such as a blood vessel. Multiple detectors, which may be filtered
to provide different colors, can be utilized for detecting the
depth of a target, for example the blood vessel, so that light can
be focused to the appropriate depth for treatment. Thus, scanning
can be in three dimensions. Since depth is to some extent
controlled by wavelength, a fiber laser, the output wavelength of
which is programmable over a limited range, may be utilized to
control skin depth both for detection and treatment. In each
instance, the treatment may be effected solely by focusing
radiation to a selected point, water at the point normally being
what is heated, or by the effect of such focusing coupled with
selective absorption by the desired target at the wavelength
utilized. The chromophor, while typically water, could also be
blood or melanin. Further, when treating blood vessels, since there
is no need for hemoglobin as a chromophore, the vessel can be
compressed during treatment, for example by applying pressure to
the vessel. This can permit denaturation and shrinkage of the
vessel wall, which can result in a more permanent closure of the
vessel and in the potential to permanently close larger vessels.
The location and size of the islands of treatment/damage can be
adjusted for different size, type and location of vessel.
Similarly, for hair removal, since melanin need not be targeted,
there is no requirement for high melanin content in the hair shaft
or follicle, facilitating the easier treatment of gray and blond
hair.
[0056] For port wine stains, wavelength can be in a range of 0.9 to
1.85 .mu.m for water absorption or 0.38 to 1.1 .mu.m for hemoglobin
absorption with a fill factor of 10% to 80%, and preferably, 30% to
50%. The light source can be an arc lamp with filtering and
masking.
[0057] The teachings of this invention are also particularly
adapted for skin rejuvenation treatments by collagen regeneration.
In such treatments, since collagen is not itself a chromophor, a
chromophor such as water in the tissues or blood in the papillary
dermis or below typically absorbs radiation and is heated to heat
the adjacent collagen, causing selective damage or destruction
thereof which results in collagen regeneration. Perturbing blood
vessels in the region can also result in the release of fibroblasts
which trigger the generation of new collagen. While such treatments
may be made only along the line of a wrinkle or other blemish to be
treated, such treatment is typically performed over a relatively
large area undergoing treatment. In accordance with the teachings
of this invention, such treatments can be more effectively
performed by heating selective portions 214, with perhaps a 30% to
50% fill factor, resulting in significant collagen regeneration
with less trauma and pain to the patient. Such procedure may be
performed over a relatively large area A or, utilizing techniques
similar to those discussed above for blood vessels, may be
performed by periodically firing a beam when over a wrinkle, the
beam being traced in a predetermined pattern and fired only when
over selected points on the wrinkle, or being moved to track a
wrinkle and periodically fired while thereover. Also, as for other
treatments where the teachings of this invention are employed,
healing occurs relatively quickly so that a subsequent treatment,
to the extent required, might generally be performed within a few
weeks of an initial treatment, and certainly in less than a
month.
[0058] Typically, a bump in the skin occurs when collagen is
heated, the bump resulting from contraction of the collagen. Thus,
this technique can be used not only to remove wrinkles but also to
remove other skin blemishes such as acne or chicken pox scars or
other scars in the skin and may also be utilized for treating
cellulite. While the bump may recede after approximately a month,
the heating also increases the thickness-to-length ratio of the
collagen in the area, thus increasing the collagen thickness,
resulting in much of the improvement from skin rejuvenation/blemish
removal being reasonably permanent.
[0059] Other skin blemishes treatable by the teachings of this
invention include stretch marks, which differ from wrinkles in that
these marks are substantially flush with the surface, the collagen
shrinkage and regeneration as a result of heating reducing these
marks. Hypotropic scarring, the raised scars which occur after
surgery or certain wounds, can also be treated by reducing blood
flow to the vessels of the scar in much the same way that port wine
stains are treated above.
[0060] In addition to hair removal, treatment of vascular lesions,
and skin resurfacing, the teachings of this invention can also be
used to target and destroy a sebaceous gland or glands, for example
to treat acne, to target and destroy pockets of subcutaneous fat,
to treat cellulite and to do skin resurfacing on areas where such
treatments cannot currently be performed, for example neck and
hands, where the damage caused using standard skin resurfacing
techniques does not normally heal. The treating of only small
islands in such areas should leave sufficient undamaged skin
structure for healing to occur. The teachings of this invention
may, as indicated above, also be utilized for tattoo removal, for
treating pigmented lesions, for treating hypotropic and other
scars, stretch marks, acne and chicken pox scars and other skin
blemishes and for treating various other conditions which may exist
in the patient's body at depths of less than approximate 4 mm, for
example, various skin cancers and possibly PFB. For skin tumors, a
combination may be used of a feedback system that localizes the
position of the tumor and a robotic system that insures complete
thermal destruction of the tumor. Psoriasis may be treated in
substantially the same way with substantially the same parameters
as for port wine stain. The teachings may also be used to treat
intredermal parasites such as larva migrans, which can be detected
and selectively killed using the teachings of the invention.
[0061] There are three general ways in which the invention may be
utilized for tattoo removal. The first is by using a wavelength or
wavelengths absorbed by the tattoo ink, preferably with short, high
fluence pulses, to break up or destroy the ink in and between
cells. The second technique involves destroying the cells
containing the ink, targeting either the ink or water in the cells,
causing the ink to be released and removed by the body's lymphatic
system. Here long pulses in the millisecond to second range, having
low power and high energy, would typically be utilized. In a third
technique, an ablation laser would be used to drill 1 to 2 mm spots
into the tattoo, ablating or vaporizing both cells and tattoo ink
in these areas. With a small fill factor, in for example the 10% to
80% range, and preferable the 10% to 30% range, such small damage
spots heal well, permitting the tattoo to be progressively
lightened and ultimately removed for each of the three treatments.
A randomized pattern on each treatment is also preferable to
interference of the removal pattern.
[0062] A particular problem for which the teachings of this
invention are particularly adapted is the treating of birthmarks or
other pigmented lesions in the epidermis. Such lesions are
generally difficult to treat without blistering using conventional
treatment. By using islands of damage with a fill factor of 1% to
50%, and preferably 10% to 30%, and with a spot size of 100 microns
to 1/2 mm, it is possible to treat such lesions without scarring.
Since the treatment in this case is so close to the surface,
focusing is not necessary. A similar treatment, with similar fill
factor could be used for treating port wine stains or tattoos, but
in either of these cases, focusing would be required since the
treatment is at a greater depth. In all cases, a first treatment
might result in only the lightening of the treated area. Once the
treated portion has healed, which generally would occur in a few
weeks to a month with an islands of damage treatment, one or more
additional treatments can be performed to further lighten the
treated area until the lesion, port wine stain, tattoo or the like
is removed. In each instance, dead cells resulting from the
treatment containing melanosites, ink or the like, would be removed
by the body, normally passing through the lymphatic system.
[0063] Thus, a technique has been provided (a) which permits
various therapeutic treatments on a patient's body at depths up to
approximately 4 mm, (b) which permits only islands of damage in
three dimensions to occur, thereby facilitating healing (by
permitting continued blood flow and cell proliferation between skin
layers and islands of damage 214) and reducing patient discomfort,
(c) which permits targeting of specific components for treatment
without damage to surrounding parts of the patient's body, thereby
more efficiently using the applied radiation while also reducing
peripheral damage to the patient's body as the result of such
treatment (d) which permits treatment of all skin types using
substantially the same parameters for a given treatment, thereby
simplifying treatment set-up and treatment safety, and (e) which
permits the wavelength utilized for treatment to be optimally
selected for the depth of treatment, rather than being restricted
to a wavelength optimally absorbed by a targeted chromophore. In
fact, while the wavelengths selected for the teachings of this
invention normally have significant water absorption, one of the
criteria in selecting wavelengths is that they are not,
particularly for deeper depths, highly absorbed, even by water, so
that the radiation can reach desired depths without losing
substantial energy/photons to absorption. The concentration of
photons/energy at target portions 214 increases energy at these
portions more than enough to compensate for reduced absorption at
the wavelength utilized. This invention thus provides an entirely
new and novel technique for performing such treatments.
[0064] FIGS. 1-21 illustrates various optical components suitable
for use in optical system 212. In these figures FIGS. 1-9B
illustrate various systems for delivering radiation in parallel to
a plurality of target portions 214. The arrays of these figures are
typically fixed focus arrays for a particular depth d. This depth
may be changed either by using a different array having a different
focus depth, by selectively changing the position of the array
relative to the surface of the patient's skin or to target volume V
or by controlling the wavelength(s) of the radiation. FIGS. 10-13
show various optical objective arrays which may be used in
conjunction with the scanning or deflector systems of FIGS. 14-19
to move to successive one or more focused portions 214 within
target volume V. Finally, FIGS. 20 and 21 show two different
variable focus optical systems which may, for example, be moved
mechanically or manually over the patient's skin to illuminate
successive portions 214 thereon.
[0065] Referring to these figures in greater detail, FIGS. 1, 1A
and 1B show a focusing element 1 on a substrate 3, the focusing
element having a border which is in a hexagonal pattern (FIG. 1), a
square pattern (FIG. 1A), and a circular or elliptical pattern
(FIG. 1B). Standard optical materials can be used for these
elements. While the hexagonal and square patterns of FIG. 1 and
FIG. 1A can completely fill the working area of the focusing
element plate 4, this is not true for the element pattern of FIG.
1B. Radiation from source 210 would typically be applied
simultaneously to all of the focusing elements 1; however, the
radiation could also be applied sequentially to these elements by
use of a suitable scanning mechanism, or could be scanned in one
direction, illuminating/irradiating for example four of the
elements at a time.
[0066] FIGS. 2 and 2A are cross-sectional views of a microlens
system fused in a refracting material 8, for example, porous glass.
The refractive index for the material of lenses 5 must be greater
than the refractive index of refracting material 8. In FIG. 2, beam
11 initially passes through planar surface 10 of refracting
material 8 and is then refracted both by primary surface 6 and by
secondary surface 7 of each microlens 5, resulting in the beam
being focused to a focal point 12. The process is reversed in FIG.
2A, but the result is the same.
[0067] In FIGS. 2B and 2C, the incident beam 11 is refracted by a
primary lens surface 6 formed of the refracting material 8.
Surfaces 6 and 7 for the various arrays can be either spherical or
aspherical.
[0068] In FIGS. 3 and 3A, the lens pieces 15 are mounted to a
substrate and are in an immersion material 16. The refraction index
of lens pieces 15 are greater than the refraction index of
immersion material 16. Immersion material 16 can be in a gas (air),
liquid (water, cryogen spray) or a suitable solid Gas and liquid
can be used for cooling of the skin. The immersion material is
generally at the primary and secondary plane surfaces, 13 and 14,
respectively. In FIG. 3A, the primary surface 6 and secondary
surface 7 of each lens piece 15 allows higher quality focusing to
be achieved. For FIGS. 3B and 3C, the lens pieces 15 are fixed on a
surface of a refracting material 8, the embodiment of FIG. 3C
providing a deeper focus than that of FIG. 3B, or that of any of
other arrays shown in FIGS. 3A-3C for a given lens 15. The lens
arrays shown in FIGS. 3A-3C are a preferred lens arrays for
practicing the teachings of this invention.
[0069] FIGS. 4-4C show Fresnel lens surfaces 17 and 18 formed on a
refracting material 8. Changing the profile of Fresnel lens surface
17 and 18, the relationship between the radius of center 17 and
ring 18 of the Fresnel surface, makes it possible to achieve a
desired quality of focusing. The arrays of FIGS. 4B and 4C permit a
higher quality focusing to be achieved and are other preferred
arrays. Surfaces 17 and 18 can be either spherical or
aspherical.
[0070] In FIGS. 5 and 5A, the focusing of an incident beam 11 is
achieved by forming a holographic lens 19 (i.e., a photographic
hologram) on a surface of refracting material 8. Holographic lenses
19 may be formed on either of the surfaces of refracting material 8
as shown in FIGS. 5 and 5A or on both surfaces. FIG. 5B shows that
the holographic material 20 substituted for the refracting material
8 of FIGS. 5 and 5A. The holographic lens is formed in the volume
of material 20.
[0071] In FIGS. 6 and 6A, the focusing elements are formed by
gradient lenses 22 having primary plane surfaces 23 and secondary
plane surfaces 24. As shown in FIG. 6A, such gradient lenses may be
sandwiched between a pair of refracting material plates 8 which
provide support, protection and possibly cooling for the
lenses.
[0072] FIGS. 7, 7A and 7B illustrate various matrix arrays of
cylindrical lenses 25. The relation of the lengths 26 and diameters
27 of the cylindrical lenses 25 can vary as shown in the figures.
The cylindrical lens 25 of FIGS. 7A and 7B provide a line focus
rather than a spot or circle focus as for the arrays previously
shown.
[0073] FIGS. 8-8C are cross-sectional views of one layer of a
matrix cylindrical lens system. The incident beam 11 is refracted
by cylindrical lenses 25 (FIGS. 8 and 8A) or half cylinder lenses
29 (FIGS. 8B and 8C) and focus to a line focus 28. In FIGS. 8B and
8C, the cylindrical lenses 29 are in the immersion material 16.
Primary working optical surface 30 and secondary optical working
surface 31, which may be spherical or aspherical, allowing high
quality focusing to be achieved. As shown in FIGS. 7-8C the line
focuses for adjacent lenses may be oriented in different
directions, the orientations being at right angles to each other
for certain of the lenses in these figures.
[0074] In FIGS. 9, 9A and 9B, a matrix of focal spots is achieved
by passing incident beam 11 through two layers of cylindrical
lenses 32 and 35. FIGS. 9A and 9B are cross-sections looking in two
orthogonal directions at the array shown in FIG. 9. By changing the
focal distance of primary layer lens 32, having a surface 33, and
secondary lens 35, having a surface 36, it is possible to achieve a
rectangular focal spot of a desired size. Primary layer lens 32 and
secondary layer lens 35 are mounted in immersion material 16.
Lenses 32 and 35 may be standard optical fibers or may be replaced
by cylindrical lenses which may be spherical or aspherical.
Surfaces 34 and 37 can be of optical quality to minimize edge
losses.
[0075] FIG. 10 shows a one lens objective 43 with a beam splitter
38. The beam 11 incident on angle beam splitter 38 divides and then
passes through the refracting surfaces 41 and 42 of lens 43 to
focus at central point 39 and off-center point 40. Surfaces 41 and
42 can be spherical and/or aspherical. Plate 54 having optical
planar surfaces 53 and 55 permits a fixed distance to be achieved
between optical surface 55 and focusing points 39, 40. Angle beam
splitter 38 can act as an optical grating that can split beam 11
into several beams and provide several focuses.
[0076] In FIG. 11, a two lens 43,46 objective provides higher
quality focusing and numerical aperture as a result of optimal
positioning of optical surfaces 41, 42 and 44. All of these
surfaces can be spherical or aspherical. Optical surface 45 of lens
46 can be planar to increase numerical aperture and can be in
contact with plate 54. Plate 54 can also be a cooling element as
previously discussed.
[0077] FIG. 12 differs from the previous figures in providing a
three lens objective, lenses 43, 46 and 49. FIG. 13 shows a four
lens objective system, the optical surfaces 50 and 51 of lens 52
allowing an increased radius of treatment area (i.e., the distance
between points 39 and 40).
[0078] FIGS. 14, 14A and 14B illustrate three optical systems which
may be utilized as scanning front ends to the various objectives
shown in FIGS. 10-13. In these figures, the collimated initial beam
11 impinges on a scanning mirror 62 and is reflected by this mirror
to surface 41 of the first lens 43 of the objective optics.
Scanning mirror 62 is designed to move optical axis 63 over an
angle f. Rotational displacement of a normal 64 of mirror 62 by an
angle f causes the angle of beam 11 to be varied by an angle 2f.
The optical position of scanning mirror 62 is in the entrance pupil
of the focusing objective. To better correlate between the diameter
of scanning mirror 62 and the radius of the working surface (i.e.,
the distance between points 39 and 40) and to increase the focusing
quality, a lens 58 may be inserted before scanning mirror 62 as
shown in FIG. 14A. Optical surfaces 56 and 57 of lens 58 can be
spherical or aspherical. For additional aberration control, a lens
61 may be inserted between lens 58 and mirror 62, the lens 61
having optical surfaces 59 and 60.
[0079] FIGS. 15, 15A and 15B are similar to FIGS. 14, 14A and 14B
except that the light source is a point source or optical fiber 65
rather than collimated beam 11. Beam 66 from point source 65, for
example the end of a fiber, is incident on scanning mirror 62 (FIG.
15) or on surface 57 of lens 58 (FIGS. 15A, 15B).
[0080] FIGS. 16 and 16A show a two mirror scanning system. In the
simpler case shown in FIG. 16, scanning mirror 67 rotates over an
angle f2 and scanning mirror 62 rotates over an angle f1. Beam 63
is initially incident on mirror 67 and is reflected by mirror 67 to
mirror 62, from which it is reflected to surface 41 of optical lens
43. In FIG. 16A, to increase the numerical aperture of the focusing
beam, increase work area on the skin and decrease aberration
between scanning mirrors 62 and 67, an objective lens 106 is
inserted between the mirrors. While a simple one lens objective 106
is shown in this figure, more complex objectives may be employed.
Objective lens 106 refracts the beam from the center of scanning
mirror 67 to the center of scanning mirror 62.
[0081] In FIG. 17, scanning is performed by scanning lens 70 which
is movable in direction s. When scanning lens 70 is moved to an off
center position 73, optical surface 68 refracts a ray of light
along optical axis 71 to direction 72.
[0082] In FIG. 18, scanning is performed by rotating lens 76 to,
for example, position 77. Surface 74 is planar and surface 75 is
selected so that it does not influence the direction of refracted
optical axis 72. In FIG. 19, scanning is performed by the moving of
point source or optical fiber 65 in direction s.
[0083] FIGS. 20 and 21 show zoom lens objectives to move the island
of damage to different depths. In FIG. 20, a first component is
made up of a single lens 81 movable along the optical axis relative
to a second component which is unmovable and consists of two lenses
84 and 87. Lens 84 is used to increase numerical aperture. To
increase numerical aperture, range of back-focal distance and
decrease focal spot size, optical surfaces 79, 80, 82, 83 and 85
can be aspherical. The relative position of the first and second
components determines the depth of focal spot 12.
[0084] FIG. 21 shows zoom lens objectives with spherical optical
surfaces. The first component is made up of a single lens 90
movable with respect to the second component along the optical
axis. The second component, which is unmovable, consists of five
lenses 93, 96, 99, 102, and 105. The radius of curvature of
surfaces 88 and 89 are selected so as to compensate for aberrations
of the unmovable second component. Again, the depth of focus may be
controlled by controlling the distance between the first and second
components. Either of the lens systems shown in FIGS. 20 and 21 may
be mounted so as to be movable either manually or under control of
control 218 to selectively focus on desired portions 214 of target
volume V or to non-selectively focus on portions of the target
volume.
[0085] While the invention has been shown and described above with
reference to a number of embodiments, and variations on these
embodiments have been discussed, these embodiments are being
presented primarily for purposes of illustration and the foregoing
and other changes in form and detail may be made in these
embodiments by one skilled in the art without departing from the
spirit and scope of the invention which is be defined only by the
appended claims.
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