U.S. patent application number 11/468279 was filed with the patent office on 2007-04-26 for method and apparatus for monitoring and controlling thermally induced tissue treatment.
This patent application is currently assigned to RELIANT TECHNOLOGIES, INC.. Invention is credited to Kin F. Chan, Leonard C. DeBenedictis, Basil M. Hantash, Thomas R. Myers, Robert Kehl Sink, B. Wayne III Stuart, Oliver Stumpp.
Application Number | 20070093798 11/468279 |
Document ID | / |
Family ID | 37809540 |
Filed Date | 2007-04-26 |
United States Patent
Application |
20070093798 |
Kind Code |
A1 |
DeBenedictis; Leonard C. ;
et al. |
April 26, 2007 |
Method and Apparatus for Monitoring and Controlling Thermally
Induced Tissue Treatment
Abstract
A method and apparatus for thermal treatment of tissue by
irradiating the skin with electromagnetic energy is disclosed.
Sources of electromagnetic energy include radio frequency (RF)
generators, lasers, and flashlamps. The apparatus includes either a
positional sensor or a dosage evaluation sensor, or both types of
sensors. These sensors provide feedback to a controller. The
controller may control the electromagnetic source parameters, the
electromagnetic source activation, and/or the sensor measurement
parameters. An additional scanning delivery unit may be operably
coupled to the controller or to the sensors to provide a controlled
distribution of electromagnetic energy to the target region of the
skin. The use of positional measurement sensors and dosage
evaluation sensors permits the controller to automatically
determine the proper electromagnetic source parameters including,
for example, pulse timing and pulse frequency.
Inventors: |
DeBenedictis; Leonard C.;
(Palo Alto, CA) ; Chan; Kin F.; (San Jose, CA)
; Stuart; B. Wayne III; (Santa Cruz, CA) ; Myers;
Thomas R.; (Palo Alto, CA) ; Sink; Robert Kehl;
(Mountain View, CA) ; Hantash; Basil M.; (East
Palo Alto, CA) ; Stumpp; Oliver; (Palo Alto,
CA) |
Correspondence
Address: |
FENWICK & WEST LLP
SILICON VALLEY CENTER
801 CALIFORNIA STREET
MOUNTAIN VIEW
CA
94041
US
|
Assignee: |
RELIANT TECHNOLOGIES, INC.
464 Ellis Street
Mountain View
CA
|
Family ID: |
37809540 |
Appl. No.: |
11/468279 |
Filed: |
August 29, 2006 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60712358 |
Aug 29, 2005 |
|
|
|
Current U.S.
Class: |
606/12 ; 606/9;
607/115; 607/88 |
Current CPC
Class: |
A61B 2018/00476
20130101; A61B 2017/00106 20130101; A61B 2034/2051 20160201; A61B
18/14 20130101; A61N 5/062 20130101; A61B 2034/2048 20160201; A61B
2034/2059 20160201; A61B 34/20 20160201; A61B 2034/2055 20160201;
A61B 2034/2065 20160201; A61B 18/203 20130101; A61B 2034/2063
20160201; A61B 2018/00452 20130101; A61B 2090/3958 20160201; A61B
2090/373 20160201; A61B 2090/395 20160201; A61B 2090/378 20160201;
A61B 2017/00022 20130101 |
Class at
Publication: |
606/012 ;
606/009; 607/088; 607/115 |
International
Class: |
A61B 18/18 20060101
A61B018/18; A61N 1/00 20060101 A61N001/00; A61N 5/06 20060101
A61N005/06 |
Claims
1. An apparatus for controlled fractional tissue treatment
comprising: an electromagnetic source that generates
electromagnetic energy; a manually movable handpiece that delivers
the electromagnetic energy to a target region of human skin; a
positional sensor that measures at least one positional parameter
of the handpiece; and a controller operably connected to the
positional sensor, the controller adjusting in real-time at least
one operational parameter of the apparatus in response to the at
least one positional parameter measured by the positional sensor,
said adjustment causing the electromagnetic energy to create a
fractional treatment for the target region of human skin.
2. The apparatus of claim 1, further comprising: a dosage
evaluation sensor that measures a skin response to the fractional
treatment created by the electromagnetic energy at the target
region of human skin, wherein the controller further adjusts in
real-time at least one operational parameter of the apparatus in
response to the measurements of the dosage evaluation sensor, said
adjustment controlling the fractional treatment created by the
electromagnetic energy.
3. The apparatus of claim 2, wherein the positional sensor is a
non-mechanical positional sensor.
4. The apparatus of claim 3, wherein the controller is not
configured to maintain a scanner rate substantially proportional to
a handpiece velocity and/or speed over a preselected range of
velocities and wherein a laser pulse rate of the electromagnetic
source is adjusted in proportion to a handpiece velocity and/or
speed.
5. The apparatus of claim 2, wherein the positional sensor
comprises a magnetic positional sensor.
6. The apparatus of claim 2, wherein the dosage evaluation sensor
comprises two sensors that generate data corresponding to a skin
condition prior to the fractional treatment or portion thereof and
to a skin condition following said fractional treatment or portion
thereof.
7. The apparatus of claim 2, wherein a treatment zone density is
adjusted in response to the measurements of the dosage evaluation
sensor.
8. The apparatus of claim 2, wherein the dosage evaluation sensor
is configured to measure a response to at least one prior treatment
pulse to evaluate the appropriate treatment level for at least one
subsequent pulse.
9. The apparatus of claim 1, wherein the positional sensor is a
non-mechanical positional sensor.
10. The apparatus of claim 9, wherein the controller adjusts in
real-time at least one operational parameter of the electromagnetic
source to affect the fractional treatment by causing at least one
of a new treatment rate, a new treatment density, and a new
treatment pattern in response to measurements by the nonmechanical
positional sensor.
11. The apparatus of claim 1, wherein the electromagnetic source is
an optical source that generates an optical beam and the apparatus
further comprises an optical scanner that directs the optical beam
to multiple locations at the target region.
12. The apparatus of claim 11, wherein the controller maintains a
scanner rate substantially proportional to a handpiece velocity
and/or speed over a preselected range of velocities.
13. The apparatus of claim 1 1, wherein the controller adjusts a
laser pulse rate in proportion to a variable handpiece velocity
and/or speed.
14. The apparatus of claim 11, wherein the scanner blurs the
optical beam along the treatment zone by a predefined amount by
adjusting a scanning rate of the optical scanner or pulse duration
of the optical source.
15. The apparatus of claim 1, wherein the positional sensor
comprises a plurality of positional sensors that are configured to
measure positional parameters that span two-dimensional space
and/or three-dimensional space.
16. The apparatus of claim 1, wherein the positional sensor
comprises at least one of an accelerometer and a gyroscope.
17. The apparatus of claim 1, wherein the positional sensor
comprises a magnetic positional sensor.
18. The apparatus of claim 17, wherein the magnetic positional
sensor comprises at least two loop antennas.
19. The apparatus of claim 1, wherein the positional sensor
comprises at least two transmitter-receiver pairs whereby a
wireless communication occurs between the transmitter and the
receiver and positional parameters are calculated from at least one
of time-of-flight measurements and phase measurements of the
wireless communication signals.
20. The apparatus of claim 1, wherein the positional sensor
comprises an ultrasonic transmitter and an ultrasonic receiver.
21. The apparatus of claim 1, further comprising multiple light
sources to illuminate the skin and wherein the controller
discrimates between two images illuminated with separate
illumination sources.
22. A method for controlled fractional tissue treatment comprising:
directing electromagnetic energy via a handpiece toward a target
region of human skin; manually moving the handpiece across the
target region; sensing at least one positional parameter of the
handpiece; and automatically adjusting in real-time at least one
operational parameter of the electromagnetic energy in response to
the at least one positional parameter, said adjustment controlling
the fractional treatment created by the electromagnetic energy.
23. The method of claim 22 wherein the step of sensing a positional
parameter comprises the step of optically sensing a positional
parameter using an optical positional sensor that is mechanically
coupled to the handpiece.
24. The method of claim 23, wherein the step of optically sensing a
positional parameter further comprises applying a contrast
enhancing agent into or onto the skin, and the contrast enhancing
agent enhances the signal to noise ratio of the optical positional
sensor.
25. The method of claim 23, wherein optical contrast for the
optical positional sensor is enhanced by the step of creating
treatment zones.
26. The method of claim 25 wherein the step of creating treatment
zones comprises ablating tissue.
27. The method of claim 23, wherein optical contrast for the
optical positional sensor is enhanced by applying an optical
contrast enhancing agent to the human skin.
28. The method of claim 27, wherein the total optical absorption of
the optical contrast enhancing agent in the wavelength range of
300-400 nm is higher than the total optical absorption in the
wavelength range of 400-700 nm.
29. The method of claim 27, wherein the total optical absorption of
the optical contrast enhancing agent in the wavelength range of
750-1000 nm is higher than the total optical absorption in the
wavelength range of 400-700 nm.
30. The method of claim 27, further comprising the steps of
illuminating the contrast enhancing agent with a wavelength in the
range of 300-1000 nm and detecting a fluorescent signal from the
contrast enhancing agent substantially in the wavelength range of
350-1050 nm.
31. The method of claim 27, wherein the step of applying an optical
contrast agent comprises spraying and/or applying the optical
contrast agent using one or more of rollers, stamps, and
stencils.
32. The method of claim 27, wherein the optical contrast enhancing
agent is applied with a pattern with nonuniform spacing between
adjacent figures.
33. The method of claim 27, wherein the step of applying the
optical contrast agent comprises the step of attaching an adhesive
to the skin in which the optical contrast enhancing agent is
embedded.
34. An apparatus for controlled fractional tissue treatment
comprising: source means for generating electromagnetic energy;
manually movable handpiece means for delivering the electromagnetic
energy to a target region of human skin; first sensor means for
measuring at least one positional parameter of the handpiece means;
second sensor means for measuring a skin response to the fractional
treatment created by the electromagnetic energy at the target
region of human skin; and control means operably connected to the
first and second sensor means, for adjusting in real-time at least
one operational parameter of the apparatus in response to the
measurements from the first and second sensor means, said
adjustment causing the electromagnetic energy to create a
fractional treatment for the target region of human skin.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C.
.sctn.119(e) to U.S. Provisional Patent Application Ser. No.
60/712,358, "Method and Apparatus for Monitoring and Controlling
Thermally Induced Tissue Treatment," by Leonard C. DeBenedictis,
George Frangineas, Kin F. Chan, B. Wayne Stuart III, Robert Kehl
Sink, Thomas R. Myers and Basil Hantash, filed Aug. 29, 2005. The
subject matter of all of the foregoing is incorporated herein by
reference in their entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a method and apparatus for
dermatological tissue treatment, and more particularly, to
controlling dosage from an electromagnetic source based on
measurements of a handpiece motion and/or skin tissue response.
[0004] 2. Description of the Related Art
[0005] Many electromagnetic dermatological treatment systems
require extensive training before physicians and nurses develop the
skills to deliver energy uniformly over a treatment region, such as
the face, neck, chest, or back. In many cases, physicians and
nurses do not treat uniformly, resulting in uneven treatment, over
treatment, or under treatment. There is a need to create more
uniform photothermal and/or radio-frequency (RF) treatment,
particularly for large areas.
[0006] Additionally, not all patients respond the same way to the
same level of treatment. So even if precisely the same laser energy
dose is delivered to two different patients, the response of each
patient may be substantially different. Within a single patient,
the skin response may vary from region to region. Treatment of the
forehead may respond differently than treatment of the neck, for
example. If uniform treatment parameters are used for all patients
or for all regions, then the treatment parameters will typically be
designed for the most sensitive patient or the most sensitive
region in order to avoid undesirable side effects. Designing for
the most sensitive region or patient will frequently lead to
undertreatment of other regions or patients.
[0007] Many medical laser systems for the treatment of
dermatological skin conditions function by pressing a footpedal to
trigger the delivery of a single pulse of treatment energy. This
type of treatment apparatus is slow and has a lot of repetitive
motions, which can be tiring to the operator. Other laser treatment
systems fire identical pulses at a constant pulse repetition rate
as the user moves the handpiece across the tissue. This system
requires skill and increases the risks of over- or under-treatment
in the hands of an unskilled operator. Therefore, there is also a
need for an approach to electromagnetic treatment that provides
controlled dosage and adjusts the dosage level in real time to
prevent over- and/or under-treatment.
[0008] Weckwerth U.S. Pat. No. 6,758,845 describes the use of
optical measurements of regularly spaced indicia that are placed on
or adjacent to the treatment region, but the concept is limited by
the application of regularly spaced indicia that are counted to
measure distance traveled by a handpiece. This requires the precise
positioning of indicia to avoid errors. In addition, the visible
indicia may be difficult to remove following treatment, and may
leave an unsightly pattern on the skin following treatment.
[0009] Weckwerth '845 and Talpalriu U.S. Pat. No. 6,171,302
describe mechanical roller systems for tracking handpiece travel.
These can be unreliable, for example, when used with gel due to a
lack of friction between the mechanical roller and the skin
surface. This leads to drop outs and errors in measurements of
positional parameters. In addition, mechanical rollers can become
rusted or gummed up so that they no longer spin easily, which makes
dropouts and errors more likely. Wearing out of mechanical parts
leads to similar errors.
[0010] Weckwerth '845 describes other systems that measure position
of the handpiece indirectly, through the interaction with reference
planes or points outside the target area, rather than measuring the
target area directly. With this approach, the location of the
treatment surface relative to the reference surface must be
measured or controlled. In addition, these systems only measure one
coordinate for the handpiece, which means that motion of the
handpiece across the target tissue due to change in orientation of
the handpiece may not be accounted for by the sensor systems. This
leads to inaccuracies.
[0011] For treatment of large areas, an automatic laser control
system is needed for adjusting laser treatment parameters in real
time in response to the handpiece position, velocity, and/or
acceleration or in response to the laser treatment itself. Thus,
there is a need for an apparatus and method for a feedback loop
that increases the effectiveness of treatment by controllably
responding to treatment variables such as treatment speed,
handpiece angle, handpiece acceleration, patient to patient
variability, region to region variability within the same patient,
etc. There is also a need for an apparatus and method that
preferably enable faster and more reproducible treatments, that
require less training and skill by the operator and/or that
controllably respond to treatment variables. The apparatus and
method preferably will also increase effectiveness without
increasing side effects or invasiveness, treat with lower pain and
side effects, directly measure treatment efficacy and/or progress
for use in a feedback loop either alone or with other inputs
instead of relying primarily on accurate delivery of a
predetermined treatment dosage or on measurement of handpiece
positional parameters, monitor biological response and treatment
variables for improved biological predictability, efficacy, and
safety, and/or permit better control of dosage, for example for
photo-dynamic therapy (PDT) treatments, laser hair removal, or
fractional laser resurfacing.
SUMMARY OF THE INVENTION
[0012] In general, the present invention comprises an apparatus and
a method for treatment using feedback from one or more sensors that
are used to measure handpiece positional parameters and/or the skin
response to thermal or ablative treatment that is caused by the
delivery of electromagnetic energy to the skin. The electromagnetic
energy may be radio frequency (RF) or optical. The positional
sensors and dosage evaluation sensors can be used separately or
they can be advantageously combined to allow treatment to vary in
response to a combination of skin response and handpiece positional
parameters.
[0013] In one embodiment of the invention, a combination of
relative and absolute handpiece positional measurements is measured
to determine the positional changes of the handpiece relative to
the treatment area.
[0014] In one embodiment of the invention, skin shrinkage is
measured with a dosage evaluation sensor. In other embodiments of
the invention, one or more measured responses of the skin include
changes in one or more of the following: skin birefringence, skin
water content, skin elasticity, skin mechanical damping parameters,
skin color, skin features such as blood vessels and pigmented
lesions, skin thickness, skin texture, and wrinkles. These and
other skin changes may be measured usng one or more types of
technology such as capacitive sensors, (hyper-) spectral imaging,
terahertz imaging, optical coherence tomography, confocal
microscopy, ultrasonic imaging, coherent detection, thermal
detectors, thermal imaging systems, etc. Other skin responses and
measurements can also be used.
[0015] In one embodiment of the invention, the output of an erbium
doped fiber laser is collimated and deflected by a scanning
delivery unit such as a galvanometer scanner or a starburst scanner
as described in pending U.S. Application No. 60/652,891 and in
corresponding U.S. Application No. 11/158,907, which are
incorporated by reference herein, to create a series of figures at
the treatment region.
[0016] In another aspect of the invention, the scanning rate of the
scanning delivery unit is controlled by a controller to deliver a
predefined pattern or dosage even if the handpiece velocity changes
within a chosen range.
[0017] In one embodiment of the invention, a contrast enhancing
agent is used to enhance the signal to noise ratio of the
positional sensor. For example, FD&C Blue #1 can be applied to
the surface of the skin to create an improved signal for a
positional sensor comprising an optical mouse chip, CCD array, or
other detector array, preferably with at least 25 elements. Using
at least 25 elements as a 5.times.5 array is preferred because this
allows sufficient image resolution to observe the changes in
positional parameters and/or dosage response. If fewer detector
elements are used, a more sophisticated algorithm and/or more
sophisticated electronics generally will be typically required in
order to distinguish changes in handpiece positional parameters
and/or skin response. Other contrast enhancing agents are
fluorescent or provide maximum contrast enhancement with IR or UV
illumination. Wavelength selective coatings on the optical elements
of the system may be used in conjunction with fluorescent contrast
enhancing agents to filter out one or more illumination
wavelengths. For example, the wavelength selective coatings can be
designed to filter out light that is used to enhance the response
of an optical positional sensor in order to improve the signal to
noise ratio for a fluorescent emission signal at a different
wavelength.
[0018] The contrast enhancing agent may be applied as a uniform or
nonuniform pattern of similar or dissimilar shapes. This pattern of
contrast enhancing agent can be applied using rollers, stamps,
sprays, and/or stencils, for example. The contrast enhancing agent
may also be applied onto or into an adhesive substance such as used
in a temporary tattoo.
[0019] In selected embodiments of the invention, the positional
sensor comprises one or more of the following: a mechanical mouse
wheel or roller ball, non-concentric coils, an accelerometer, a
gyroscope, transmitter(s) and receiver(s) that can be used to
measure distance, a Doppler radar system, an ultrasonic time of
flight measurement, etc.
[0020] In another embodiment of the invention, leading and trailing
dosage evaluation sensors are used to measure the differential skin
response due to thermal treatment.
[0021] In another embodiment of the invention, the scanning motion
of a scanning delivery unit is not changed, but the pulse rate or
pulse timing of the electromagnetic source is changed by the
controller in response to measurements by at least one positional
sensor and/or at least one dosage evaluation sensor. The pulse
timing and scanner patterns may be chosen such that the beam is
intentionally dragged across the treatment region to reduce the
treatment intensity and/or to increase the size of each treatment
zone created by each energy pulse.
[0022] In another embodiment of the invention, healthy skin is
spared in regions between individual treatment zones to create
fractional treatment. The spared tissue helps to promote rapid
healing of the wounded area, prevent scarring, and allow higher
treatment levels than are otherwise possible without side effects.
The measurement of positional parameters can be used to accurately
space the treatment zones from one another so that treatment dosage
can be properly controlled.
[0023] In another embodiment, the density of fractional treatment
is controlled through the use of feedback from positional and/or
dosage sensors.
[0024] Other aspects of the invention include methods, devices, and
systems corresponding to the approaches described above, as well as
applications of the foregoing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The invention has other advantages and features which will
be more readily apparent from the following detailed description of
the invention and the appended claims, when taken in conjunction
with the accompanying drawings, in which:
[0026] FIG. 1 is a diagram of an embodiment of the invention that
incorporates a positional sensor and a dosage evaluation
sensor.
[0027] FIGS. 2A, 2B, and 2C are diagrams of an embodiment of the
invention that incorporates an optical source, a starburst scanner
wheel, and an optical positional sensor. FIG. 2C also depicts one
possible treatment pattern created by this embodiment.
[0028] FIGS. 3A, 3B, and 3C are illustrations of patterns that can
be applied to the treatment region or to regions adjacent to the
treatment region to enhance the measurements of the optical
positional sensor shown in FIG. 1.
[0029] FIG. 4 is a diagram of an embodiment of the invention
wherein one or more accelerometers are attached to the handpiece to
measure positional parameters of the handpiece in up to three
dimensions and/or up to three angular orientations.
[0030] FIG. 5 is a diagram of an embodiment of the invention
wherein transmitters and receivers are used to triangulate the
position of the handpiece to measure positional parameters in up to
three dimensions and/or up to three angular orientations.
[0031] FIGS. 6 and 7 are diagrams of embodiments of the invention
wherein at least one ultrasonic transmitter and at least one
ultrasonic receiver are mechanically coupled to the handpiece. The
embodiment depicted in FIG. 6 utilizes an ultrasonic time-of-flight
measurement. The embodiment in FIG. 7 utilizes an ultrasonic
reflection measurement.
[0032] FIG. 8 illustrates an embodiment of the invention wherein
polarized imaging is used to measure changes in the birefringence
of the skin.
[0033] FIG. 9 is a diagram showing the use of leading and trailing
dosage evaluation sensors in accordance with the invention for the
measurement of the differential skin response to particular
treatment parameters.
[0034] FIGS. 10 and 11 illustrate embodiments of the invention that
measure the skin response to particular treatment parameters by
measuring the signature of a shock wave created by an energy pulse
incident on the skin. FIG. 10 illustrates an apparatus for
measuring the shock wave signature with a piezo-electric material.
FIG. 11 illustrates an apparatus for measuring the shock wave
signature with a reflected probe beam.
[0035] FIG. 12 is a diagram of an embodiment of the invention
wherein one or more coil sensors are used to measure positional
parameters of the handpiece.
[0036] FIG. 13 illustrates measurements created by a system
according to FIG. 12.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0037] This invention describes an electromagnetic system with
automatic adaptive control of (photothermal and/or RF) treatment
parameters and/or activation. A nominal pattern and treatment rate
may be defined when the system begins treatment and this treatment
pattern can be modified based on algorithms that describe the skin
response to treatment and/or the positional parameters of the
handpiece. Which positional parameter measurements or skin response
measurements are made may depend upon particular measurement
results. For example, if the handpiece is moving very rapidly
across the skin and treatment power is proportional to relative
handpiece speed, then bulk heating of the tissue may be a concern.
In this case, the dosage evaluation sensors may be instructed by
the controller to measure skin parameters that are associated with
blistering due to over treatment. If movement is slow, bulk heating
and blistering may be less of a concern and more of the processing
power of the controller can be used to make more accurate
measurements of velocity with the positional parameter sensors
instead. Detailed embodiments of the invention are described in the
examples given below.
[0038] In some embodiments, a distinction can be made between
micro-dosimetry and macro-dosimetry measurements. Micro-dosimetry
measurements are substantially limited to one or more zones that
are about to be treated by a pulse or a set of simultaneous pulses.
For example, measurement of a 1.2 mm diameter area that is
cocentered with a 1 mm diameter area that is about to be treated is
micro-dosimetry because the measurement is substantially limited to
the region that is about to be treated with a future pulse or a
future set of essentially simultaneous pulses. In contrast,
macro-dosimetry measurements are used to evaluate larger areas of
skin to produce an average measurement of regions that include both
areas that are about to be treated (or that have just been treated)
and adjacent regions. In some embodiments, a dosage evaluation
sensor is used to produce micro-dosimetry or macro-dosimetry
measurements in accordance with the feedback loops of this
invention.
[0039] FIG. 1 is a diagram of an embodiment of the invention
showing a manually movable handpiece 100 that is configured to
deliver electromagnetic treatment energy to the skin 150 in the
treatment region. The electromagnetic source 110 generates
electromagnetic energy 130 that treats the skin. The controller 115
activates or adjusts one or more parameters of the electromagnetic
source for the purpose of affecting treatment. The handpiece 100
may contain a controller 115 that may comprise a computer, a radio
frequency generator, and/or laser driver electronics. In other
configurations, the controller 115 is located external to the
handpiece 100 and is operably connected to the handpiece 100 to
control treatment parameters. The system may also include an
optional scanning delivery unit 120 that is operably coupled to a
scanner control 125 that scans the electromagnetic energy 130 over
the treatment region of the skin 150. An optional contact plate 139
that is mechanically coupled to the handpiece 100 may be used to
make good electrical or optical contact with the skin 150 to
enhance controlled delivery of the electromagnetic energy 130. A
positional sensor 180 measures positional parameters of the
handpiece and a dosage evaluation sensor 160 measures skin response
to treatment.
[0040] While the operator manually moves the handpiece 100 in
direction 101 or after the operator has manually moved the
handpiece 100, the positional sensor 180 measures one or more
positional parameters of the handpiece 100 and the dosage
evaluation sensor 160 measures the skin response to treatment
parameters. The positional sensor 180 and the dosage evaluation
sensor 160 communicate with the controller 115 and/or with the
scanner control 125. The controller 115 and/or the scanner control
125 materially alter the treatment in real time in response to the
positional parameter measurements and/or in response to the dosage
evaluation measurements.
[0041] In some embodiments, the feedback loops comprising the
controller 115 and/or the scanner control 125 in combination with
the positional sensor 180 and/or the dosage evaluation sensor 160
can be used to provide automated control of treatment parameters
such as treatment location, treatment zone overlap, treatment
energy, treatment depth, treatment power, treatment zone pattern,
treatment cooling (including pre-cooling and post-cooling), etc.
These treatment parameters can be controlled through adjustment of
device parameters that affect treatment such as optical focus or
spot size, pulse width, pulse energy, pulse timing, pulse
frequency, laser power, laser wavelength, spray cooling volume,
spray cooling timing, etc.
[0042] Optionally, the controller 115 may be operably connected to
the scanner control 125, which can be helpful for reducing the
number of wiring connections from the sensors. The controller 115
may serve the function of both the controller 115 and the scanner
control 125 as shown in the embodiment of FIG. 2A. For example, the
functions of both the controller 115 and the scanner control 125
can be performed by a computer or a CPU operably coupled to a
memory that stores a computer program. The positional sensor 180
and the dosage evaluation sensor 160 may also be operably coupled
or may be combined in a single component. For example, a CCD chip
can be used to measure both shifts in movement and skin
response.
[0043] Detailed embodiments of several components in FIG. 1 are
described in the examples given below. In one embodiment, the
electromagnetic source 110 delivers RF energy and the scanning
delivery unit 120 comprises an electrical switching network
comprising electrically controlled relays connected to multiple
electrical contact pads in the contact plate 139 that is made of a
nonconductive substance such as molded plastic. The scanning
delivery system 120 can deliver patterns of energy across the
treatment region sequentially or multiple relays can be activated
to energize a plurality of treatment zones simultaneously.
[0044] In general, an electromagnetic source 110 is a radio
frequency (RF) source, an optical source, or a combination of the
two. A RF source generates electromagnetic energy with a frequency
in the range of 0.1-20 MHz and preferably in the range of 0.5-8
MHz. An optical source generates light, which is defined for this
application as electromagnetic energy with a wavelength in the
range of 300 to 12,000 nm. Optical energy is preferred over radio
frequency energy because it permits the energy to be directed more
accurately and more easily to the desired locations on the skin. RF
energy can also be desirable, particularly for applications where
deeper penetration or targeting of particular buried layers of skin
are desired. The choice of RF or optical energy may also be made to
reduce interference with a chosen type of dosage evaluation sensor
and/or position sensor.
[0045] In a preferred embodiment, the electromagnetic source 110 is
a laser and the electromagnetic energy 130 is a laser beam.
Examples of lasers are Nd:YAG lasers, diode lasers, erbium fiber
lasers, CO.sub.2 lasers, Er:YAG lasers, Er:glass lasers,
flashlamp-pumped lasers, free electron lasers, thulium fiber
lasers, Raman shifted fiber lasers, dye lasers, gas lasers, Argon
lasers, and ytterbium fiber lasers.
[0046] The skin response can be measured by one or more dosage
evaluation sensors 160 employing one or more types of technology
such as capacitive sensors, (hyper-) spectral imaging, terahertz
imaging, optical coherence tomography, confocal microscopy,
ultrasonic imaging, coherent detection, thermal detectors, thermal
imaging, etc. In addition, one or more dosage evaluation sensor(s)
160 may measure skin birefringence, skin water content, skin
elasticity, skin mechanical damping parameters, skin color, skin
features such as blood vessels and pigmented lesions, skin
thickness, skin texture, wrinkles, etc. Other types of measurement
technology and other dermatological features and tissue properties
that can be measured will be apparent to those skilled in the
art.
[0047] A mechanical mouse or roller wheel with an encoder can also
be used as a positional sensor 180. It is preferable, however, to
use a non-mechanical positional sensor, which does not rely
primarily on moving parts to measure positional parameters.
Non-mechanical positional sensors advantageously improve
measurement reliability on slippery surfaces and reduce the chance
of mechanical failure in comparison to mechanical positional
sensors.
[0048] In one embodiment of a non-mechanical positional sensor 180
coil sensors are used as described by Ben-Haim et al in U.S. Pat.
No. 6,788,967, which is herein incorporated by reference. Three
sensor coils that are mechanically coupled to the handpiece 100 in
the appropriate orientations can be used to measure positional
information, for example up to three dimensions and/or up to three
angular orientations for the handpiece when the sensor coils are
placed in the magnetic field generated by at least two radiators.
Other geometries and numbers of radiators and sensor coils are
possible for measurement of one-dimensional to six-dimensional
positional parameters of the handpiece. Other non-mechanical
positional sensors such as optical positional sensors are described
below and may be detachable from the handpiece.
[0049] One example of the use of coil sensors is shown in more
detail in FIG. 12. In FIG. 12, a magnetic positional sensor 1280 is
located outside the handpiece 1200 and the magnetic source 1281 is
attached to the handpiece 1200. The magnetic source 1281 can
comprise three magnetic field source elements 1285A-C. The magnetic
field source elements are arranged such that their axes span
three-dimensional space. The axes may, for example, directed in
three mutually orthogonal directions. The magnetic positional
sensor can comprise three magnetic sensor elements 1284A-C that can
be located at a reference point and are arranged to span
three-dimensional space.
[0050] In a preferred embodiment, each of the magnetic field source
elements 1285A-C and each of the magnetic field sensor elements
1284A-C comprise a loop antenna that is tuned to a desired
frequency, for example a frequency of about 10 kHz. The loop
antennas 1285A-C for the magnetic field source elements 1282 can
each be driven with a current source, for example an op-amp current
source. Alternately, a single current source 1288 can be
electronically switched to power each of the loop antennas of the
magnetic field source elements 1285A-C sequentially.
Preferentially, the system is operated in the near field of each of
the magnetic field source elements 1285A-C and each of the magnetic
field sensor elements 1284A-C, but operation in the far field is
also possible. The source elements 1284A-C can be sequentially
powered in order to time division multiplex the source signals. The
controller 1215 comprises receiver electronics for measuring the
response detected by the magnetic field sensors. The receiver
electronics portion of the controller may be collocated with the
magnetic field sensor elements 1284A-C or may be integrated with
the other electronics of the controller 1215. The controller
comprises appropriate electronics to demultiplex the received
signals to identify the measured magnetic field intensity due to
each of the source elements. To synchronize the systems,
particularly in the case of time division multiplexing, a common
clock can be used for the source and receiver electronics. Other
configurations of source, receiver, multiplexing/demultiplexing,
and electronic systems will be apparent. For example, additional
embodiments and refinements of appropriate magnetic field systems
can be found in U.S. Pat. Nos. 4,613,866, 4,737,794, 4,742,356, and
5,307,072, each of which is incorporated herein by reference.
[0051] In alternate embodiments, the magnetic field source elements
1285A-C are located at one or more reference points outside the
handpiece and the magnetic field sensor elements 1284A-C are
attached to the handpiece. The location of and direction of the
treatment beam(s) emitted from the handpiece relative to the
reference coordinate system is then measured. For treatment on the
face, the handpiece 1200 can include the magnetic source 1281, and
a small earbud that is placed within the ear of the patient can
contain the magnetic positional sensor 1280. To improve accuracy
and to determine whether the earbud has fallen out or shifted, a
second magnetic positional sensor (not pictured) may be used, for
example in the opposite ear of the patient. If there is a
discrepancy between the redundant sensors, the system can alert the
physician, using for example an audible alarm.
[0052] The choice of which of the magnetic source 1281 and the
magnetic positional sensor 1280 is located at the reference
point(s) and which is located at the handpiece 1200 can be chosen
based on the sources of electromagnetic interference and objects of
electromagnetic field distortion, such as metal plates. For the
example above, it is anticipated that there is a scanning motor
element, such as for example used in FIG. 2 to spin the scanner
wheel 220 around axis 221, that generates a significant magnetic
field. The effects of a scanning motor element on the measurement
system can be reduced by locating the source in the handpiece
instead of the sensor. In an alternate configuration, there may be
no electromagnetic elements in the handpiece, for example, and the
sensor would then be optimally located in the handpiece and the
source located at a reference point. In addition, the system can be
calibrated empirically to compensate at least partially for any
fixed elements that distort the magnetic field.
[0053] In one embodiment of a magnetic field system as described in
FIG. 12, a Polhemus Patriot digital tracker system (available from
Polhemus of Colchester, Vt.) is used to measure the position of the
handpiece relative to a reference point. An example of measurements
created using this system are shown in FIG. 13, which shows a 2D
projection 1301 of a 3D data set for half of a face.
[0054] In one embodiment of the invention, one or more measured
handpiece positional parameters include handpiece position or
handpiece angle (angular orientation) or the time derivatives of
these two parameters including handpiece velocity, handpiece
acceleration, handpiece angular velocity, and handpiece angular
acceleration. Handpiece positional parameters can be absolute or
can be relative to the treatment region.
[0055] To enhance the serviceability of the apparatus and to allow
handpieces to be interchanged and thus share expensive components,
the handpiece may be detachable from one or more of the following:
the electromagnetic source 110, the controller 115, and the scanner
controller 125. To reduce the weight of the handpiece, these
components may be located outside the handpiece. Alternatively, to
enhance portability of the apparatus, these components may be
included inside the handpiece.
[0056] The scanning delivery unit is configured to receive the
electromagnetic energy 130 and deliver the electromagnetic energy
130 to the skin 150 regardless of where the other components are
housed. For example, the electromagnetic source 110 may be a laser.
The electromagnetic radiation may be coupled into an optical fiber,
optical waveguide, or articulating arm for delivery to the
handpiece. The handpiece can accept optical energy by using a fiber
coupling or a fiber collimator. Similarly, it will be evident to
those skilled in the art that the sensors 160 and 180 should be
operably coupled to the controller 115, but do not need to be
located inside the handpiece.
[0057] The controller 115 and scanner control 125 may be separate
components as in FIG. 1 or may be combined as a single controller
as shown in FIG. 2A.
[0058] In the embodiment of FIG. 2A, a laser source 210 is used as
the electromagnetic source. In this embodiment, a manually movable
handpiece 200 is configured to deliver an optical beam 230 of
electromagnetic energy to the treatment region of the skin 250. The
handpiece 200 contains a controller 215 comprising a computer
and/or laser driver electronics. The controller 215 controls an
optical source 210 and a scanning delivery unit 220 to affect one
or more parameters such that treatment is materially affected. The
optical source 210 generates an optical beam 230 that is directed
to an optional scanning delivery unit 220. The scanning delivery
unit 220 deflects the laser beam 230 to different treatment zones
on or within the skin 250 as will be described in greater detail
below. For clarity, only one beam position is shown in FIG. 2A. A
dichroic mirror 232 and a contact plate 239 that are substantially
transparent at the wavelength of the laser beam 230 may
advantageously be included in particular embodiments. The deflected
laser beam 230 is delivered through the dichroic mirror 232 and
contact plate 239 to the skin 250. A beam delivery lens 231 can be
used to focus the deflected beam 230 within the epidermis 251,
dermis 252, or other layers of the skin 250. The focal point of the
optical beam 230 may be below the skin surface or the beam may be
diverging or collimated as it enters the skin 250. The dosage
evaluation sensor 260 is mechanically coupled to the handpiece 200
and measures the skin response to treatment.
[0059] In the embodiment of FIG. 2, the positional sensor 280
measures the position of the handpiece relative to the surface of
the skin 250. In alternate embodiments, the positional sensor 280
could measure position, velocity, and/or acceleration of handpiece
relative to the surface of the skin 250. An illumination source 282
emits illumination 283 that is collimated by an illumination
delivery lens 284 for delivery to the surface of the skin 250.
Collimating the illumination 283 increases alignment tolerances,
improves uniformity of the illumination on the skin surface, and
allows the illumination source 282 to be placed further from the
treatment region than would otherwise produce a uniform profile of
illumination 283 at the surface of the skin 250. The illumination
283 is scattered from the surface of the skin 250 or from a
contrast enhancing agent 290 that is placed into or onto the skin
250. The spectral reflectivity of the dichroic mirror 232 and the
reflective prism 287 are designed to substantially reflect the
wavelength of the scattered illumination 285. A detector lens 286
is placed in the optical path from the skin to the positional
sensor 280 to image the surface of the skin 250 on the optical
positional sensor 280. Examples of optical positional sensors 280
include an optical mouse chip (Agilent Technologies, Palo Alto,
Calif.), a CCD camera, or an optical sensor array of at least two
sensor elements. Preferably the optical sensor array has at least
25 sensor elements, arranged as a 5.times.5 array to have
sufficient resolution to accurately quantify a range of velocity
resolutions easily. Preferably, this optical positional sensor is
silicon-based so that it can be manufactured cheaply using bulk
manufacturing processes and cheap material sources that have been
developed for the electronics industry. Other configurations will
be evident to those skilled in the art.
[0060] In FIG. 2A, the direction 201 of handpiece motion (not
shown) is essentially perpendicular to the plane of the page. FIG.
2B illustrates a side view of the handpiece that shows the
direction of motion 201 of the handpiece 200. For simplicity,
internal elements of the handpiece 200 are not shown in FIG. 2B.
The handpiece 200 is manually moved by the operator in direction
201 while the positional sensor 280 measures one or more positional
parameters of the handpiece and the dosage evaluation sensor 260
measures one or more skin responses to treatment. The positional
sensor 280 and the dosage evaluation sensor 260 communicate with
the controller 215. In response to the measurements, the controller
215 adjusts the optical treatment parameters in real time to
materially affect the photothermal treatment. For example, the rate
of laser firing can be adjusted to be proportion to the velocity of
the handpiece 200 to create a predefined treatment pattern or a
uniform treatment.
[0061] An example of a dosage evaluation sensor 260 is a capacitive
sensor as shown in FIGS. 2A, 2B, and 2C. The capacitive sensor 260
can measure the level of desiccation of selected layers of the skin
due to treatment. The measurements from the capacitve sensor 260
can be used to calculate the proper dosage parameters for the
treatment and make adjustments to the treatment parameters using
the controller 215. The capacitive sensor 260 can also be used to
evaluate whether a region of skin has blistered. By imaging the
junction between the dermis and the epidermis, the capacitive
sensor can determine whether separation of the dermis and epidermis
has occurred. In other embodiments, sensors for measuring or
imaging skin resistivity can be used as dosage evaluation sensors
260 to evaluate blistering and skin moisture content. A capacitive
sensor array that is commonly used for fingerprint measurements is
an example of a sensor that could be used as a capacitive sensor
260.
[0062] FIG. 2C shows a treatment pattern comprising separated
microscopic treatment zones 256 that can be created with this
approach as the handpiece 200 is moved across the treatment region
257 in the direction 201. In this embodiment, separated microscopic
treatment zones 256A, 256B, and 256C can be created in the skin as
described in copending U.S. application Ser. Nos. 10/367,582,
10/751,041, 10/888,356, and 60/652,891, which are herein
incorporated by reference. Preferably, the treatment zones 256 are
created in a predefined pattern that is invariant with the relative
velocity or acceleration of the handpiece 100. Other patterns will
be evident to those skilled in the art. Substantially uniform
treatment coverage can be created by appropriately choosing optics,
treatment parameters, and laser pulse timing. Additionally, the
capacitive sensor 260 may provide feedback to the controller 215 so
that treatment parameters can be adjusted to reduce the density of
microscopic treatment zones 256 or to reduce the treatment power in
response to overtreatment.
[0063] In an alternative embodiment, the pattern can be
intentionally varied according to a predefined algorithm where
treatment rate is varied in real time in response to changes in the
velocity or acceleration of the handpiece and where the treatment
pattern is not predefined. For example, the treatment pattern can
be controlled in real time by the user by appropriately adjusting
the position, velocity, or acceleration of the handpiece. In some
treatments, it is desirable to allow the operator to have control
over the level of treatment through the use of velocity. For
example, if the user treats quickly, the system may be configured
to allow a higher level of treatment response as measured by the
dosage evaluation sensor 260. If the user treats slowly, then the
maximum allowable treatment response can be reduced. Thus, the user
is able to control the treatment settings simply by changing
positional parameters of the handpiece. Thus, the treatment
pattern, treatment density, treatment intensity, and other
treatment parameters may not be predefined, but may be defined
through an automated response to measured positional parameters, to
measured treatment response, or to both measured positional
parameters and measured treatment response. An electronic or
computer interface (not pictured) may be provided to allow
switching on or off different modes of user control.
[0064] In another embodiment, a treatment status map is displayed
on a monitor (not shown) for the user or the patient to observe.
The positional sensor 280 can be used to measure the location
within the treatment region of the tissue response that is measured
by the dosage evaluation sensor 260. In this way, a map can display
which parts of the treatment region have been treated and how each
part of the treatment region has responded to treatment. The user
can take the information on this map to make treatment uniform over
the entire treatment region or to have treatment vary in a
desirable manner such as treating area with deep wrinkles more
heavily than less wrinkled areas. Alternatively, the system can be
configured to automatically reduce or disable treatment in the
regions that have already been adequately treated as the user
continues to move the handpiece over the treatment region. A
picture or schematic representation of the treatment region, such
as line drawing of a face for treatment of wrinkles on the face,
can be used as a background for a computer display of the map of
the treatment response measurements.
[0065] The use of a postional sensor 280 and/or a dosage sensor 260
to create a map can be used beneficially, particularly with small
beam sizes less than 1 mm in their smallest dimension. Using such a
map, treatment can be turned on or off based on whether treatment
has covered that area or not. The advantage of using a beam size of
less than 1 mm is that the granularity of the beam size for
treatments that are visually apparent after treatment will be less
noticeable for such small beam sizes. Thus, the use of a positional
sensor 280 and or a density sensor 260 is particularly suited to
fractional treatment and/or treatments with a small beam size of
less than 1 mm.
[0066] Controller 215, optical source 210, and other components may
be external to the handpiece 200 instead of being included inside
the handpiece as illustrated in FIG. 2A. The optical beam 230 can
propagate to the handpiece through free space, through an
articulated arm, or through a waveguide, such as an optical fiber.
The handpiece 200 may be mechanically separable from or
mechanically separate from the external components and the
handpiece 200 may be configured to receive the optical beam 230
and/or the signal from the controller 215.
[0067] In a preferred embodiment, the electromagnetic source 210 is
a single mode pulsed erbium doped fiber laser with a peak output
power in the range of 5-50 W and a wavelength in the range of
1.52-1.62 .mu.m. This laser source can be focused to an optical
spot size in the range of 30-600 .mu.m and preferably 60-300 .mu.m
on the surface of the skin. Pulse energies in the range 2-100 mJ
and preferably in the range of 8-20 mJ can be used for these ranges
of optical spot size, wavelength, and power. This preferred
embodiment does not include surface skin cooling, but such cooling
can be included if desired to reduce damage to the epidermis and
dermal-epidermal junction.
[0068] The scanning delivery unit 220 used in this embodiment is a
scanner wheel rotating at least 360.degree. around an axis 221 as
described in detail in U.S. Application No. 60/652,891 and in
corresponding U.S. application Ser. No. 11/158,907, which are
incorporated by reference herein. Other scanner types will be
apparent to those skilled in the art. For example, galvanometer
scanners, pseudo stationary deflection (PSD) scanners as described
in copending U.S. application Ser. No. 10/750,790, which is also
incorporated by reference herein, polygonal scanners, light valves,
LCD screens, MEMS based reflective scanners, and translation stages
can be used for the scanning delivery unit for delivery of optical
energy. Multiple scanning delivery units can be used in such
systems to control multiple axes of deflection. For example, two
galvanometer scanners can be used in series to scan the laser beam
in two directions to cover an area on the surface of the skin 250.
Alternatively, single scanning units can cause beam deflection in
two directions as described in detail in U.S. application Nos.
60/652,891 and 11/158,907.
[0069] One algorithm that can be used to control operational
parameters of the scanning delivery unit 220 is to adjust the
rotational speed of a double or single wheel PSD scanner and the
laser firing rate in proportion to the velocity of the handpiece.
This allows microscopic treatment zones of fractional resurfacing
to be placed in a predefined pattern on the skin.
[0070] Another algorithm for controlling treatment is to adjust the
firing of the laser in approximate proportion to the relative
velocity of the handpiece to create a predefined density of
treatment zones. A uniform distribution of treatment zones across a
treatment region by overlapping or abutting treatment zones can
also be achieved. For example, if the scanner 220 shown in FIG. 2A
is controlled to spin at a constant angular velocity as the
handpiece 200 is moving across the surface of the skin 250, the
laser firing can be pulsed to create the desired density of
treatment zones within the treatment region by firing the laser
only when it is aligned with a particular facet of the scanner that
creates the desired distribution or density of treatment. Not every
facet needs to be used. For a particular velocity, every facet may
be used. If the velocity is reduced by a factor of three from this
velocity, then only every third facet can be used to keep the same
density. Preferably, the algorithm maintains a uniform distribution
of treatment zones within the treatment region. Spinning the
scanning wheel 220 at a constant angular velocity is preferable to
requiring the angular velocity of the scanning wheel 220 to be
proportional to the speed of the handpiece 200 because this
configuration reduces the complexity of the motors, associated
drive electronics, and encoders that are used to accurately control
the angular velocity of the scanning wheel 220.
[0071] In another embodiment, the scanner wheel 220 is run at a
velocity that drags the optical beam 230 across the treatment
region. This wheel velocity may even be in the opposite direction
of the direction that would compensate for movement of the
handpiece. This intentional dragging of the optical beam 230 across
the surface of the skin 250 can be created with either
variable-velocity or fixed-velocity scanner systems. With the
fixed-velocity system, for example, the pulse duration of the laser
beam can be adjusted according to the velocity of the handpiece 200
such that the optical beam is dragged across the skin by
approximately the same distance with each pulse. By changing the
angular velocity of the scanner wheel 220 or by changing the pulse
duration for the optical beam 230, the distance over which the
optical treatment occurs for each pulse can be changed. The
controlled dragging of the optical beam can, for example, be used
to increase the fill factor for a fractional resurfacing treatment
by making each microscopic treatment zone larger by increasing the
distance over which optical treatment occurs. As the velocity of
the handpiece 200 is reduced, the increased pulse duration
prescribed by this algorithm may cause a reduction in treatment
response as measured by the dosage evaluation sensor 260.
Therefore, it may be desirable to increase the pulse energy to keep
the tissue response the same.
[0072] The contact plate 239 beneficially reduces optical
scattering from the skin surface for the treatment beam by creating
a smooth surface that can be used to precisely and reproducibly
position the skin relative to the focus depth of the optical beam
230. The contact plate 239 can also act as a thermal heat spreader
or can conduct heat away from the surface to actively cool the skin
when connected to a cooling source (not shown). The contact plate
239 and dichroic mirror 232 can comprise sapphire, fused silica,
borosilicate glass, transparent plastic, or other transparent
materials. The contact plate 239, dichroic mirror 232, and other
optical components may have optical coatings applied on one or more
sides to increase the efficiency of energy delivery into the skin
or to enhance the reflectivity or transmission of the illumination
283 from the illumination source 282.
[0073] In some embodiments, the contact plate 239 may be
undesirable and may be omitted. For example, in ablative laser
treatments, it may be desirable to have the surface of the skin be
mechanically free to enhance the ablation response of
treatment.
[0074] To enhance the ability of the optical positional sensor 280
to read the positional parameters of the handpiece 200, a contrast
enhancing agent 290 can be applied onto or into the skin 250. For
example, uniform application of a dye to the surface of the skin
250 can preferentially decorate certain features, such as skin
wrinkles or hair follicles, to create shapes that can be detected
as objects by the positional sensor 280. The contrast enhancing
agent 290 must be non-toxic when applied onto or into a patient's
skin in amounts suitable for adequately enhancing measurements by
the positional sensor 280. Preferably, the contrast enhancing agent
and the materials and geometry chosen for the handpiece 200 and
contact window 239 allow the handpiece 200 to slide easily over the
surface of the skin 250.
[0075] Examples of contrast enhancing agents 290 are carbon
particles, India ink, and FD&C Blue #1. Many other dyes, inks,
particulates, etc. can be used as contrast enhancing agents when
applied to the skin and when used with the appropriate positional
sensor 280. The wavelength illumination source 282 can be chosen to
maximize the signal to noise ratio of the measurement of the
positional parameters of the handpiece 200. For example, a red LED
with a peak wavelength in the range of 600 to 640 nm can be used
with FD&C Blue #1.
[0076] In many cases, the contrast enhancing agent will be chosen
such that it has a low absorption of the treatment energy or of the
treatment wavelength in the case of optical treatment energy. In
this way, the contrast enhancing agent will not interfere with the
deposition of the treatment energy in the treatment region. In some
cases, the contrast enhancing agent is chosen such that a
measurable or observable parameter changes in response to the
treatment energy. A change in the contrast enhancing agent can be
used to determine where treatment has occurred, which allows the
treatment to be touched up in areas where it is not even or
uniform.
[0077] It is desirable to choose a contrast enhancing agent 290
that can be removed without abrasive or harsh scrubbing.
Alternatively, a removal facilitation substance (not shown) can be
applied prior to application of the contrast enhancing agent 290 to
allow the dye to be removed more easily. Dimethicone, urea, and
arginine are examples of removal facilitation substances. These
substances may be applied prior to the contrast enhancing agent 290
to facilitate subsequent removal of the contrast enhancing agent
290. These substances can be applied using common solvents such as
water, alcohol, or oil. Concentrations of the removal facilitation
substance can be used, for example, in the range of 0.001M to
0.1M.
[0078] It is desirable to choose a contrast enhancing agent 290
that is not clearly visible when illuminated with typical room
light and/or sunlight. Contrast enhancing agents 290 are said to be
"hypovisible" if and only if the contrast enhancing agent is not
readily visible on otherwise bare skin with the naked eye when
illuminated with 400-650 nm light when the contrast enhancing agent
290 is applied such that the response of the detector 280 is
beneficially and substantially enhanced when using an illumination
wavelength from 300-400 nm or from 700-1100 nm. The use of
hypovisible contrast enhancing agents 290 is desirable because the
contrast enhancing agent 290 will be less visible after treatment
even if not all of the contrast enhancing agent 290 is removed from
the treatment region.
[0079] Many fluorescent inks, lakes, dyes, and particulates are
examples of hypovisible contrast enhancing agents 290. Fluorescing
agents are desirable because the wavelength of illumination can be
filtered by the dichroic mirror 232 or by other optical components
or coatings while the throughput of the fluorescent emission
wavelength is maximized to improve the signal to noise ratio of the
positional sensor 290. Polymer (PMMA) encapsulated fluorescent dyes
are commercially manufactured by NewWest Technologies (Santa Rosa,
Calif.). Other fluorescent materials include collagen, elastin,
FD&C Orange No. 5, flavin adenine dinucleotide, flavin adenine
mononucleotide, folic acid, niacin, nicotinamide, reduced
nicotinamide adenine dinucleotide (NADH), porphyrins, pyranine
(FD&C Green No. 7), pyridocine hydrochloride, quinine sulfate,
riboflavin, riboflavin phosphate, tryptophan, uranine
(fluorescein), or combinations thereof. The absorption and emission
spectra for these substances are well published in the art. Other
fluorescent materials that are well known in the art can also be
used as the contrast enhancing agent 290, for example Carbazine,
Coumarin, Stilbene 3, Kiton Red.
[0080] The intensity of fluorescent emission of pyranine varies
with pH. So pyranine can be used to evaluate changes in barrier
function and alert the user or automatically stop treatment or
reduce treatment intensity if a break in the stratum corneum or a
rupture of the skin occurs during treatment. Thus, the contrast
enhancing agent 290 may also be used to improve the signal to noise
ratio of the dosage evaluation sensor 260.
[0081] Indocyanine green (ICG) is an example of a contrast
enhancing agent 290. Most contrast enhancing agents 165 can be
diluted with water or other solvents to make them easier to apply
or cheaper to use. The peak wavelength of ICG varies depending on
the solvent and the concentration of ICG. For example, in water,
ICG has an IR absorption peak at approximately 700 nm for high
concentrations (e.g. 129-1290 .mu.M) and at approximately 780 nm
for low concentrations (e.g. 6.5-65 .mu.M). For ICG in blood
plasma, there is an absorption peak in the range of approximately
790-810 nm across a broad range of concentrations (6.5-1290 .mu.M).
In general, ICG typically has an absorption peak in the range of
650-850 nm for most solvents. ICG also has absorption peaks in the
UV range. ICG does not have a strong absorption peak in the range
of 400 to 650 nm, which makes it difficult to see with the naked
eye. Thus, ICG is an example of a contrast enhancing agent that has
low visibility to the human eye, but is easily discernable to a
silicon based optical detector when illuminated appropriately. In
non-fluorescing contrast enhancing agents, the wavelength (or
wavelength range) of illumination can be chosen to be in a region
where the peak absorption of the contrasting agent is at least 3
times, or preferably at least 10 times, stronger or weaker than
that of skin. It is also desirable to have the peak absorption of
the contrasting agent in the chosen wavelength (or wavelength
range) to be at least 3 times, or preferably at least 10 times,
stronger than the peak absorption within the wavelength range of
400-650 nm.
[0082] The contrast enhancing agent can also be applied in a
pattern. The pattern may comprise a uniform grid of identical FIGS.
391 in the treatment region 357 as illustrated in FIG. 3A. The
pattern may comprise a nonuniform pattern of identical FIGS. 392 in
the treatment region 357 as illustrated in FIG. 3B. The pattern may
comprise a nonuniform pattern of a plurality of different FIGS. 393
in the treatment region 357 as illustrated in FIG. 3C. Contrast
enhancing agents can be applied using stamps, rollers, sprays,
stencils, or with agent-soaked gauze pads.
[0083] Patterns of contrast enhancing agents can also be attached
to the skin using adhesives as used in temporary tattoos. As in a
temporary tattoo, a pattern can be created by printing a contrast
enhancing agent on or embedding a contrast enhancing agent in an
adhesive that attaches to the skin. The adhesive has the advantage
of being easier to remove than many of the contrast enhancing
agents that can be included in or on the adhesive. Lakes of FDA
approved colors such as FD&C Blue #1 (also packaged as
Optiguide Blue by Reliant Technologies, Palo Alto, Calif.) can be
embedded in a polymer-based tattoo adhesive and painted onto the
skin. Following treatment, these adhesive based patterns can be
removed with alcohol and light scrubbing. The use of adhesive also
allows the use of contrast enhancing agents in doses that would
otherwise be toxic to the skin because the adhesive can be designed
to provide a barrier between the skin and the contrast enhancing
agent.
[0084] Alternatively, contrast enhancing agents may be suspended in
sugar-based or gel based solutions without patterning. These
solutions can desirably be made viscous so that they do not drip
outside the treatment area.
[0085] Instead of applying a pattern of figures with a contrast
enhancing agent, the laser treatment zones may form a pattern of
figures that is used to enhance the response of the positional
sensor 280. For example, a CO.sub.2 laser can ablate portions of
the skin to create a pattern of ablated areas interspersed inside
nonablated areas. This pattern can be illuminated with an LED to
provide visible features that enhance the signal to noise ratio of
an optical mouse chip functioning as a positional sensor 280.
[0086] Other embodiments of the positional sensor 280 are
illustrated in FIGS. 4-7. Other embodiments of the dosage
evaluation sensor 260 are illustrated in FIGS. 8-11. Using one or
more of these sensors, different measurements can be made to
optimize tissue treatment levels. Treatment densities and treatment
levels can be kept constant or maintained within defined ranges by
the controller 215 which appropriately adjusts treatment parameters
of the electromagnetic source 210 and the scanning delivery unit
220.
[0087] The positional sensors and dosage evaluation sensors shown
in FIGS. 4-11 can be added to or substituted into the embodiment
shown in FIGS. 1 and 2. As will be apparent to one skilled in the
art, many of these systems can be easily designed such that the
region sensed by the dosage evaluation sensor is coincident with
the region measured by the positional sensor and the region being
treated. In situations where it is not desirable to have the two
sensors coincident or where these two types of sensors interfere,
the dosage evaluation sensor may be displaced along the x, y, or z
directions relative to the positional sensor.
[0088] While the embodiment illustrated in FIG. 2 shows delivery of
optical energy to the treatment region, monopolar or bipolar radio
frequency (RF) energy can also be used in place of optical energy
by replacing the contact plate 239 with a contact plate, contact
electrodes, or needle electrodes that are configured to deliver RF
energy to a desired treatment region under the control of a
controller 215 that comprises a RF generator.
[0089] FIG. 4 illustrates an embodiment of the invention. In this
embodiment, the positional sensor is implemented as one or more
sets of accelerometers 480 and 481 that are mechanically coupled to
the handpiece 400. The sets of accelerometers 480 and 481 can be
attached to the inside or outside of the handpiece 400. A set of
three accelerometers 480A, 480B, and 480C can be used to measure
changes in velocity in each of the three coordinate planes. The one
or more sets of accelerometers 480 and 481 can communicate with a
controller 415 that controls the operational parameters of an
electromagnetic source 410. The electromagnetic source 410 emits
electromagnetic energy 430, which is delivered to the skin 450
through a contact plate 439. The configuration illustrated in FIG.
4 can also include a scanning delivery unit (not shown), as
illustrated in FIGS. 1 and 2.
[0090] As shown in FIG. 4, a pair of accelerometers can be used to
measure angular acceleration in each of the three rotational
directions. For example, accelerometers 480A and 481A measure the
angular acceleration around a rotational axis parallel to the z
axis, accelerometers 480B and 481B measure the angular acceleration
around a rotational axis parallel to the x axis, and accelerometers
480C and 481C measure the angular acceleration around a rotational
axis parallel to the y axis. Accelerometers 480B and 481B are
displaced from each other along the z axis direction and are drawn
as overlapping in FIG. 4. Alternatively, gyroscopes can be used to
measure angular acceleration of the handpiece. MEMS based
accelerometers and gyroscopes are sold by several suppliers (e.g.
Kionix, Inc., Ithaca, N.Y.).
[0091] Measurements of acceleration or angular acceleration can be
integrated in time to produce measurements of velocity and position
or angular velocity and angular position. In many configurations,
an initial calibration and periodic recalibrations may be required
to reset the reference velocity, angular velocity, position, and/or
angular position.
[0092] Accelerometers measure absolute positional parameters of the
handpiece 400 rather than relative positional parameters of the
handpiece 400 with respect to the treatment region of the skin 450.
If relative positional parameters are desired, accelerometers can
be used when the treatment region is immobilized or when absolute
movement of the treatment region is insignificant. Alternatively,
the absolute movement of the treatment region of the skin 450 and
the absolute movement of the handpiece 400 can both be measured and
the relative motion between the handpiece 400 and the treatment
region of the skin 450 can be calculated.
[0093] Relative measurements of angular position can be used to
provide feedback to the system and disable the laser unless the
relative angle of the handpiece is within a certain angular range
relative to the surface normal from the surface of the treatment
region. This may be useful, for example, to align properly a
cooling spray and a treatment laser beam on a treatment region.
Absolute measurements of angular position are useful if the
handpiece 400 has components that are sensitive to gravity, such as
fluid-filled cavities that leak if turned upside down. Relative
measurements of position can be used to measure distance between
locations for pulsing the electromagnetic source 410.
[0094] Absolute or relative measurements of velocity, acceleration,
angular velocity, and angular acceleration are useful for
evaluating whether the handpiece has been dropped or has suddenly
slipped in an uncontrolled way, which might lead to undesired
treatment outside the desired treatment area. A combination of
relative positional parameter measurements and absolute positional
parameter measurements can be used to measure movement of the
patient. For example, if the patient suddenly moves, the difference
between the relative acceleration and the absolute accerlation
measurements may be significant. In any of the situations described
in this paragraph, the controller 415 may temporarily disable the
electromagnetic source 410 to prevent treatment in areas that are
not desired by the user.
[0095] FIG. 5 illustrates another embodiment of the invention. In
this embodiment, the positional sensor comprises at least two
pairings of transmitter and receiver that conduct either
unidirectional or bidirectional wireless communication. The
transmitters 580A-C are positioned to transmit signals to one or
more receivers 58 1A-B that are mechanically coupled to the
handpiece 500. The signals from the receivers are received by the
controller 515, which uses time of flight measurements or phase
measurements to calculate the distance between each pairing of
transmitter and receiver. These distances can be used to calculate
selected positional parameters of the handpiece, which can be done
by the controller 515. The controller 515 may be operably connected
to other components of the handpiece such as the electromagnetic
source 110, the scanner control 125, or the scanning delivery unit
120 as shown in FIG. 1. These may be located inside or outside the
handpiece 500 and, for simplicity, are not shown.
[0096] The number and location of transmitters and receivers
determines the positional parameters that can be measured. For
measuring the position of the handpiece in three dimensions, three
transmitters and one receiver can be used. For measuring the
position of the handpiece in up to three dimensions and also
measuring the angular position for up to three independent angular
directions, a second receiver can be used. For measuring all three
dimensions and all three handpiece angles, three transmitters and
three receivers are preferably used in order to have redundancy. A
simple apparatus comprises two transmitters and one receiver. This
apparatus can be used to measure the positional parameters of a
handpiece in two dimensions along a predefined surface. In an
alternate configuration, two receivers are used with one
transmitter to produce the same measurement. The particular
geometry and locations of transmitters and receivers can be
generalized by one skilled in the art.
[0097] For simplicity in the examples described below, receivers
are located on the handpiece and transmitters are located inside
the treatment region 557 or are mechanically coupled to the
treatment region 557 such that the measured positional parameters
of the handpiece will be relative to the treatment region and not
absolute measurements. Other configurations can be used if absolute
measurements are desired. Light based or other electromagnetic
communications systems can be used for these types of systems as
well.
[0098] In one embodiment, three radio frequency transmitters are
attached to a cap, preferably made of cloth or latex for ease of
use and low cost. For example, transmitters can be attached to EEG
caps for this purpose. This type of cap is useful for locating the
handpiece when treating wrinkles on the forehead or periorbital
areas of the face, for example, because the transmitters can be
mechanically coupled to the treatment region. This type of cap can
also be used with the coil measurement system described in the text
for FIG. 1. In some embodiments, single chip receivers, similar to
those commonly used in cell phones or GPS tracking systems, are
attached to the cap. Alternatively, sensors or receivers can be
attached directly to the treatment area or to other areas of the
body, such as the teeth, ears, nose, chin, etc. using adhesives. If
the sensors are placed accurately in the same place for each
treatment, for example on the same tooth, then overlay maps can be
created to illustrate the regions that were treated with each
treatment in a series.
[0099] One advantage of the accelerometer, magnetic, gyroscope, and
transmitter-receiver based measurement systems is that they can
easily be used in noncontact mode, which reduces the chance of skin
movement during treatment and allows the handpiece to be held at
different distances from the skin in order to manually adjust the
beam size that is incident on the skin surface.
[0100] Multiple positional sensors can also be used, for example,
to allow lower quality signals from each of the positional sensors.
For example, an optical mouse type sensor can be used with a
magnetic radiator coil measurement system. The combination of
multiple sensors can also be used to shut the system down if large
discrepancies were noted between or among the sensors. If different
types of sensors were used, discrepancies can be used to provide
additional information, for example, about whether the skin is
being stretched. This information can be used to detect situations
when the handpiece is not sliding properly and can be used to
provide feedback to the system and reduce localized over- and
under-treatments.
[0101] FIG. 6 shows another embodiment of the invention wherein a
manually movable handpiece 600 is configured to deliver optical
energy to the skin. An ultrasonic transmitter 680 is positioned on
one side of the contact plate 639 and an ultrasonic receiver 682 is
positioned on the opposite side of the contact window.
Time-of-flight measurements or phase measurements are recorded to
measure the distance of propagation between the transmitter 680 and
receiver 682. This can be used to measure velocity of the handpiece
600 in the direction 601 relative to the skin 650.
[0102] FIG. 7 shows an embodiment of the positional sensor and a
handpiece 700. A phased array of ultrasonic transmitters 780 is
positioned on one side of the contact plate 739 and an ultrasonic
receiver 782 is positioned on the same side of the contact window.
The phased array 780 emits a directional ultrasonic beam that can
be scattered or reflected from the surface of the skin or from one
or more features 753 within the skin to the ultrasonic receiver
782. Using phase shift, time of flight, or Doppler frequency shift
measurements, a controller (not shown) can be used to measure
positional parameters of the handpiece 700 as it moves in the
direction 701.
[0103] The ultrasonic transmitter-receiver pairs shown in FIGS. 6
and 7 can also be used as embodiments of the dosage evaluation
sensor 160 from FIG. 1 with the proper choice of frequency and
preferably used in conjunction with a velocity sensor to remove the
changes in the measurement due to velocity.
[0104] FIG. 8 shows an embodiment of the dosage evaluation sensor
160 from FIG. 1. In this embodiment, a polarized illumination
source 862 is used to illuminate the skin 850 through an
illumination lens 864 and through an optional transparent contact
plate 839. A polarized imaging system comprising an imaging sensor
860, a polarizer 867, and an imaging lens 866 are used to image the
birefringence of the treatment region of the skin 850. The imaging
sensor 860 can then be operably coupled to the controller 115 shown
in FIG. 1.
[0105] During certain types of photothermal treatment, dermal
collagen is coagulated, which causes a loss of optical
birefringence for the collagen. This change in birefringence can be
measured by the imaging sensor 850 and can be used, for example, as
the endpoint of a treatment pulse to control the duration of a
treatment pulse.
[0106] The polarizer 867 may be adjustable (automatically or
manually) to make alignment easier or more precise or to allow
comparison of cross polarization and parallel polarization
images.
[0107] The embodiment shown in FIG. 8 may also be used to measure
skin shrinkage, preferably by measuring the separation distance
between two features on the skin before and after treatment. One or
more imaging sensors 860 can be used. Shrinkage can also be
measured using a single measurement by measuring the separation
distance between individual treatment zones that start at a known
distance. For example, an ablative CO.sub.2 laser can place two
marks at a set distance of 15 mm and then the separation between
these marks can be measured to determine skin shrinkage. The
polarizer 867 may not be needed for these measurements and the
illumination source 862 may be unpolarized.
[0108] In another implementation of the dosage evaluation sensor
illustrated in FIG. 8, illumination can be used to increase the
signal level of an optical dosage evaluation sensor. White light
illumination can be used. Alternatively, sequential illumination
with different color illumination sources can be used to captre
images that are digitally processed to spectrally determine the
treatment level of the tissue components. For example, illumination
from a red LED at 660 nm and green LED at 555 nm can be used to
capture, for which the absorption of melanin and blood are
different. This will help to distinguish between treatment
lightening response of pigmented lesions and of blood vessels. The
polarizer 867 may not be needed for these measurements and the
illumination source 862 may be unpolarized.
[0109] FIG. 9 shows an embodiment of the invention that uses a
plurality of dosage evaluation sensors 960 and 961 to provide more
information than is available from a single sensor. For example,
one dosage evaluation sensor 961 can measure the dosage prior to
treatment and a second dosage evaluation sensor 960 can measure the
treatment response after treatment. In this embodiment, the two
dosage evaluation sensors 960 and 961 are operably coupled to a
controller 915 that controls the treatment parameters of the
electromagnetic source 910. The electromagnetic source 910
generates electromagnetic energy 930 that is delivered to the
treatment regions of the skin 950 through a contact plate 939 as
the handpiece is moved in a direction 901.
[0110] Using a dosage evaluation sensor 961 before treatment and
another dosage evaluation sensor 960 after treatment allows the
controller 915 to calculate how much treatment is applied for a
particular treatment setting. The controller 915 can then make
adjustments as appropriate to adjust the parameters of the
electromagnetic source 910. This dosage feedback loop allows real
time adjustment of treatment parameters.
[0111] An example of a dosage feedback loop uses a first capacitive
dosage evaluation sensor 961 and a second capacitive dosage
evaluation sensor 960. Each capacitive dosage evaluation sensor
measures the percentage of skin that has been treated with a
nonablative fractional resurfacing treatment. The first and second
capacitive dosage evaluation sensors 961, 960 are positioned in
front of and behind the treatment window such that the first
capacitive dosage evaluation sensor 961 measures the percentage of
skin that had been treated prior to the current pass of the
handpiece and the second capacitive dosage evaluation sensor 960
measures the percentage of skin that has been treated after the
current pass of the handpiece over the treatment region. The
difference between the measurements for the two sensors 960, 961
describes the percentage of skin treated during the current pass of
the handpiece over the treatement region. The calculation of the
percentage of skin treated during the current pass can be used, for
example, to avoid overtreatment caused by bulk heating of tissue by
reducing the laser treatment energy when unusually high percentages
are calculated. Other examples of appropriate dosage feedback
sensors 960, 961 are described in U.S. application Ser. No.
10/868,134, which is incorporated by reference herein.
[0112] FIGS. 10 and 11 show other embodiments of a dosage
evaluation sensor 1060/1160 that is operably connected to a
controller (not shown), which changes the treatment parameters in
response to the measurements from the dosage evaluation sensor. In
a preferred embodiment, the dosage evaluation sensor 1060/1160 is
located inside the handpiece 1000/1 100. In alternate embodiments,
the dosage evaluation sensor 1060/1160 is not located inside the
handpiece 1000/1 100. In FIG. 10, a probe radiation source 1062
generates a probe beam 1063, preferably with a pulse width of
between 0.5 and 1000 ns or between 5 and 100 ns, that is absorbed
by the skin 1050 to create a stress wave that propagates through
the interface between a piezo-electric material 1065 and the skin
1050. The probe beam 1063 may pass through an optional probe beam
delivery lens 1064 to focus the probe beam 1063 onto or into the
skin 1050. The stress wave causes the piezo-electric material 1065
to generate an electrical signal that is measured by the electrical
signal detector 1060 that is electrically connected to the
piezo-electric material 1065.
[0113] The characteristics of the generated stress wave vary based
on mechanical and optical characteristics of the skin. The probe
wavelength can be chosen such that there is a difference in
absorption within the skin between untreated and treated skin.
Alternatively, the pulse conditions are chosen such that the
mechanical response is different for treated and untreated skin.
Thus, the stress wave that is created can be measured to determine
whether the probed skin is approaching, has reached, or has
exceeded a desired level of treatment. Examples of mechanical
characteristics of the skin that can be probed using a stress wave
include elasticity, tension, and mechanical damping of the
skin.
[0114] The signature of the stress wave that is generated can be
measured using several different techniques. One technique is
illustrated in FIG. 10 and is described above. In this technique, a
transparent contact plate 1065 made of a piezo-electric material,
such as lithium niobate, generates an electrical signal in response
to a mechanical stress wave. This electrical signal can be measured
by an electronic signal detector 1060. Appropriate electronic
signal detectors 1060 are well described in the art. The probe
radiation source 1062 may be a Q-switched or mode-locked lasers.
The laser may be a diode laser, a solid state laser, an Nd:YAG
laser, a gas laser, etc.
[0115] A second technique for measuring the stress wave is to
observe the change in reflectance pattern from a beam incident on
the surface of the skin as shown in FIG. 11. In this configuration,
a probe radiation source 1162 generates a probe beam 1163,
preferably with a pulse width of between 0.5 and 1000 ns or between
5 and 100 ns, that is absorbed by the skin 1150 to create a stress
wave that propagates along the surface of the skin 1 150. The probe
beam 1163 may pass through an optional probe beam delivery lens
1164 and an optional contact plate 1165 if desired for optical or
mechanical purposes such as focusing the probe beam 1163 or
mechanically enhancing the propagation of the stress wave. A
coherent illumination source 1172 generates a coherent illumination
beam 1173 that may be focused or collimated onto the surface of the
skin using an optional coherent illumination lens 1174. The
coherent illumination beam 1173 is diffracted from the surface of
the skin by the stress wave created on the surface of the skin 1150
to create a diffracted beam 1167. The diffracted beam 1167 can be
imaged using an imaging lens 1166 onto an imaging detector 1160,
such as a CCD camera.
[0116] The components 1162, 1163, and 1164 are similar to their
analogs in FIG. 10 1062, 1063, and 1064 and can be made from the
same components as described above.
[0117] The optional contact window 1165 is preferably comprised of
a transparent material, such as fused silica or sapphire, through
which the probe beam 1163 passes.
[0118] The probe beam 1163 is absorbed by the skin 1150 to create a
stress wave in the skin 1 150. As described above for FIG. 10, the
features of the stress wave depend on the optical and mechanical
parameters of the skin. Certain features, such as the period and
damping of the stress wave, can be evaluated by measuring the
diffraction pattern from the diffracted beam 1167 that is imaged on
the surface of the imaging detector 1160.
[0119] The coherent illumination source 1172 should be a coherent
source, for example a HeNe laser. The angle of the coherent
illumination beam 1173 relative to the surface of the skin 1150 and
the angle of the imaging system relative to the surface of the skin
1150 and relative to the coherent illumination beam 1173 is
preferably aligned to maximize the measurement signal. Once a
signal has been measured, the decay constant and resonant frequency
of the stress wave can be measured with of the apparatii described
by FIGS. 10 and 11. DC filtering can also be used to improve the
signal to noise ratio of the detected signal.
[0120] With the techniques described in FIGS. 10 and 11,
preferably, only the first reflected wave is measured and
subsequent signals from scattering are temporally filtered. This
reduces confusion from multiply reflected waves. This is similar to
optical coherence tomography systems in which only the first
reflected signal is used. Depending on the particular geometry of
the apparatus, this apparatus can be used to measure bulk or
localized optical and mechanical properties of the skin, which are
changed by the treatment.
[0121] The examples presented here have all illustrated the use of
these techniques on human skin. This invention is also applicable
to treatment of other tissues of the body. For example, puncturing
the surface of toenails for treatment of nail fungus, soft palate
for treatment of disorders such as sleep apnea and snoring, hair
removal, topical delivery of pharmaceuticals or nutriceuticals, or
treatment of heart tissue for laser-based TMR treatments can all
benefit from the use of this invention.
[0122] Although the detailed description contains many specifics,
these should not be construed as limiting the scope of the
invention but merely as illustrating different examples and aspects
of the invention. It should be appreciated that the scope of the
invention includes other embodiments not discussed in detail above.
For example, in many of the examples above, lasers are used as the
embodiment, but these can be generalized to RF, flashlamp, or other
electromagnetic energy based treatments as well. Various other
modifications, changes and variations which will be apparent to
those skilled in the art may be made in the arrangement, operation
and details of the method and apparatus of the present invention
disclosed herein without departing from the spirit and scope of the
invention as defined in the appended claims.
[0123] In the specification and in the claims, reference to an
element in the singular is not intended to mean "one and only one"
unless explicitly stated, but rather is meant to mean "one or
more." In addition, it is not necessary for a device or method to
address every problem that is solvable by different embodiments of
the invention in order to be encompassed by the claims.
* * * * *