U.S. patent application number 12/135971 was filed with the patent office on 2009-03-19 for thermal surgery safety apparatus and method.
Invention is credited to James Henry Boll, Daniel Hohm, Mirko Mirkov, Rafael Armando Sierra, Richard Shaun Welches.
Application Number | 20090076489 12/135971 |
Document ID | / |
Family ID | 40130073 |
Filed Date | 2009-03-19 |
United States Patent
Application |
20090076489 |
Kind Code |
A1 |
Welches; Richard Shaun ; et
al. |
March 19, 2009 |
THERMAL SURGERY SAFETY APPARATUS AND METHOD
Abstract
A laser surgical method is disclosed including: providing a
laser surgical device including a handpiece including: an optical
delivery component that transmits laser energy from a source to a
treatment volume; and an accelerometer configured to provide
information indicative of the position of the handpiece. The method
includes using the handpiece to transmit laser energy from the
source to a plurality of positions within the treatment volume;
using the accelerometer, providing information indicative of the
position of the handpiece; determining information indicative of an
amount of energy delivered at each of the plurality of positions
within the treatment volume based on the information indicative of
the position of the handpiece, and displaying a graphical
representation indicative of the amount of energy delivered at each
of the plurality of positions within the treatment volume.
Inventors: |
Welches; Richard Shaun;
(Manchester, NH) ; Boll; James Henry; (Newton,
MA) ; Mirkov; Mirko; (Chelmsford, MA) ;
Sierra; Rafael Armando; (Palmer, MA) ; Hohm;
Daniel; (Merrimac, NH) |
Correspondence
Address: |
FOLEY & LARDNER LLP
111 HUNTINGTON AVENUE, 26TH FLOOR
BOSTON
MA
02199-7610
US
|
Family ID: |
40130073 |
Appl. No.: |
12/135971 |
Filed: |
June 9, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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60933736 |
Jun 8, 2007 |
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60987596 |
Nov 13, 2007 |
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60987617 |
Nov 13, 2007 |
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60987819 |
Nov 14, 2007 |
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60987821 |
Nov 14, 2007 |
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61018729 |
Jan 3, 2008 |
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61018727 |
Jan 3, 2008 |
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Current U.S.
Class: |
606/15 ;
606/14 |
Current CPC
Class: |
A61B 2018/00464
20130101; A61B 2018/00791 20130101; A61B 2017/00084 20130101; A61B
2017/00119 20130101; A61B 2018/00166 20130101; A61B 90/37 20160201;
A61B 2218/007 20130101; A61B 90/361 20160201; A61B 18/22 20130101;
A61B 2018/00642 20130101; A61B 18/201 20130101 |
Class at
Publication: |
606/15 ;
606/14 |
International
Class: |
A61B 18/22 20060101
A61B018/22 |
Claims
1. A laser surgical apparatus comprising: a handpiece comprising:
an optical delivery component that transmits laser energy from a
source to a treatment volume; and an accelerometer configured to
provide information indicative of the position of the handpiece; a
processor coupled to the accelerometer and the source and
controlling the laser energy transmitted to the treatment volume;
and a display; wherein the processor is configured to determine
information indicative of an amount of energy delivered at each of
a plurality of positions within the treatment volume based on the
information indicative of the position of the handpiece, wherein
the display is configured to display a graphical representation
indicative of the amount of energy delivered at each of the
plurality of positions within the treatment volume.
2. The apparatus of claim 1, wherein the processor is configured to
control the amount of energy delivered to the treatment volume
based on feedback from the accelerometer.
3. The apparatus of claim 2, wherein the accelerometer measures
acceleration along three axes.
4. The apparatus of claim 3, wherein the accelerometer is a gyro
compensated accelerometer.
5. The apparatus of claim 1, wherein the graphical representation
comprises a map of the treatment volume, wherein a plurality of
points on the map correspond to the plurality of positions within
the treatment volume, and wherein the a graphical quality of each
of the points depends on the amount of energy delivered at the
position within the treatment volume.
6. The apparatus of claim 5, wherein the graphical representation
is a three dimensional representation.
7. The apparatus of claim 1, wherein: the handpiece further
comprises a temperature sensor configured to provide information
indicative of the temperature of tissue at positions within the
treatment volume, the processor is coupled to the temperature
sensor and is configured to determine information indicative of the
temperature of each of a plurality of positions within the
treatment volume based on the information indicative of the
position of the handpiece and the information indicative of the
temperature of tissue at positions within the treatment volume, and
wherein the display is configured to display a graphical
representation indicative of the amount of energy delivered at each
of the plurality of positions within the treatment volume.
8. A laser surgical method comprising: providing a laser surgical
device comprising a handpiece comprising: an optical delivery
component that transmits laser energy from a source to a treatment
volume; and an accelerometer configured to provide information
indicative of the position of the handpiece; using the handpiece to
transmit laser energy from the source to a plurality of positions
within the treatment volume using the accelerometer, providing
information indicative of the position of the handpiece;
determining information indicative of an amount of energy delivered
at each of the plurality of positions within the treatment volume
based on the information indicative of the position of the
handpiece, and displaying a graphical representation indicative of
the amount of energy delivered at each of the plurality of
positions within the treatment volume.
9. The method of claim 8, further comprising controlling the amount
of energy delivered to the plurality of positions within the
treatment volume based on feedback from the accelerometer.
10. The method of claim 9, wherein the accelerometer measures
acceleration along three axes.
11. The method of claim 10, wherein the accelerometer is a gyro
compensated accelerometer.
12. The method of claim 8, wherein the graphical representation
comprises a map of the treatment volume, wherein a plurality of
points on the map correspond to the plurality of positions within
the treatment volume, and wherein the a graphical quality of each
of the points depends on the amount of energy delivered at the
position within the treatment volume.
13. The method of claim 5, wherein the graphical representation is
a three dimensional representation.
14. The apparatus of claim 1, wherein: the handpiece further
comprises a temperature sensor configured to provide information
indicative of the temperature of tissue at positions within the
treatment volume, and the processor is coupled to the temperature
sensor; and further comprising: using the temperature sensor,
determining information indicative of the temperature of each of a
plurality of positions within the treatment volume based on the
information indicative of the position of the handpiece and the
information indicative of the temperature of tissue at positions
within the treatment volume, and displaying a graphical
representation indicative of the amount of energy delivered at each
of the plurality of positions within the treatment volume.
15. A laser surgical apparatus comprising: a handpiece comprising:
an optical delivery component that transmits laser energy from a
source to a treatment volume; and an accelerometer configured to
provide information indicative of acceleration of the handpiece
along three axes; and a processor coupled to the accelerometer and
the source and controlling the laser energy transmitted to the
treatment volume based on feedback from the accelerometer.
16. The apparatus of claim 15, further comprising a gyroscope
configured to provide information indicative of the spatial
orientation of the handpiece, and wherein the processor is coupled
to the gyroscope and is configured to control the laser energy
transmitted to the treatment volume based on feedback from the
accelerometer and the gyroscope.
17. The apparatus of claim 16, wherein the processor is configured
to determine information indicative of an absolute position of the
handpiece based on the information indicative of acceleration of
the handpiece along three axes, and the information indicative of
the spatial orientation of the handpiece.
18. The apparatus of claim 17, wherein the processor is configured
to determine information indicative of a speed of the handpiece
based on the information indicative of acceleration of the
handpiece along three axes; and control the laser energy
transmitted to the treatment volume based on feedback using the
information indicative of the speed of the handpiece.
19. The apparatus of claim 18, wherein the information indicative
of acceleration of the handpiece along three axes comprises, for at
least one axis, a signal having an amplitude which depends on the
acceleration of the handpiece along the axis, and the processor is
configured to selectively block low frequency components of the
signal prior to integrating said signal to determine information
indicative of a speed of the handpiece along the respective
axis.
20. The apparatus of claim 18, wherein the processor is configured
to determine the speed of the handpiece along each of the three
axes based one information indicative of acceleration of the
handpiece along three axes; determine a weighted average speed of
the handpiece by calculating a weighted average of the speeds of
the handpiece along each of the three axes; and control the laser
energy transmitted to the treatment volume based on feedback using
the weighted average speed of the handpiece.
21. The apparatus of claim 20, wherein the handpiece comprises a
probe member for insertion into the treatment volume, said probe
member extending along a probe member axis, the accelerometer is
configured to provide information indicative of acceleration along
each of the three axes, one of said three axes being substantially
parallel to the probe member axis; and the processor is configured
to determined the weighted average speed of the handpiece by
calculating a weighted average of the speeds of the handpiece along
each of the three axes, wherein the axis substantially parallel to
the probe member axis is given greater weight that the other
axes.
22. A laser surgical method comprising: providing a handpiece
comprising: an optical delivery component that transmits laser
energy from a source to a treatment volume; and an accelerometer
configured to provide information indicative of acceleration of the
handpiece along three axes; using the handpiece to transmit laser
energy from the source to the treatment volume; using the
accelerometer, providing information indicative of acceleration of
the handpiece along three axes; and controlling the laser energy
transmitted to the treatment volume based on feedback from the
accelerometer.
23. The method of claim 22, wherein the handpiece further comprises
a gyroscope, and further comprising: using the gyroscope, providing
information indicative of the spatial orientation of the handpiece,
and further comprising; and controlling the laser energy
transmitted to the treatment volume based on feedback from the
accelerometer and the gyroscope.
24. The method of claim 23, further comprising: determining
information indicative of an absolute position of the handpiece
based on the information indicative of acceleration of the
handpiece along three axes, and the information indicative of the
spatial orientation of the handpiece.
25. The method of claim 22, further comprising: determining
information indicative of a speed of the handpiece based on the
information indicative of acceleration of the handpiece along three
axes; and controlling the laser energy transmitted to the treatment
volume based on feedback using the information indicative of the
speed of the handpiece.
26. The method of claim 25, further comprising: determining the
speed of the handpiece along each of the three axes based one
information indicative of acceleration of the handpiece along three
axes; determining a weighted average speed of the handpiece by
calculating a weighted average of the speeds of the handpiece along
each of the three axes; and controlling the laser energy
transmitted to the treatment volume based on feedback using the
weighted average speed of the handpiece.
27. The method of claim 17, wherein the handpiece comprises a probe
member extending along a probe member axis, and further comprising:
inserting the probe member into the treatment volume; repetitively
advancing and withdrawing the probe member within the treatment
volume; using the accelerometer to provide information indicative
of acceleration along each of the three axes, one of said three
axes being substantially parallel to the probe member axis; and
determining the weighted average speed of the handpiece by
calculating a weighted average of the speeds of the handpiece along
each of the three axes, wherein the axis substantially parallel to
the probe member axis is given greater weight that the other
axes.
28. A laser surgical apparatus comprising: a handpiece comprising:
a probe member comprising an optical delivery component that
transmits laser energy from a source to a treatment volume, said
probe member adapted for insertion into a treatment volume through
an incision in a patient; and an accelerometer configured to
provide information indicative of the position of the handpiece
relative to the incision; a processor coupled to the accelerometer
and the source and controlling the laser energy transmitted to the
treatment volume based on the information indicative of the
position of the handpiece relative to the incision.
29. The apparatus of claim 28, wherein the accelerometer is
configured to provide information indicative of a speed of the
handpiece and the processor is configured to controlling the laser
energy transmitted to the treatment volume based on the information
indicative of the speed of the handpiece.
30. A method comprising providing a handpiece comprising: a probe
member comprising an optical delivery component that transmits
laser energy from a source to a treatment volume, said probe member
adapted for insertion into a treatment volume through an incision
in a patient; and an accelerometer configured to provide
information indicative of the position of the handpiece relative to
the incision; inserting the probe member into the treatment volume
through the incision; repetitively advancing and withdrawing the
probe member within the treatment volume; transmitting laser energy
to the treatment volume; using the accelerometer to provide
information indicative of the position of the handpiece relative to
the incision; and controlling the laser energy transmitted to the
treatment volume based on the information indicative of the
position of the handpiece relative to the incision.
31. The method of claim 30, further comprising: using the
accelerometer to provide information indicative of a speed of the
handpiece; and controlling the laser energy transmitted to the
treatment volume based on the information indicative of the speed
of the handpiece.
32. A laser surgical apparatus comprising: a handpiece comprising:
an optical delivery component that transmits laser energy from a
source to a treatment volume; an accelerometer configured to
provide acceleration information indicative of an acceleration of
the handpiece; and a temperature sensor configured to provide
temperature information indicative of a temperature of tissue
within the treatment volume; and a processor coupled to the
accelerometer, the temperature sensor, and the source and
configured to control the laser energy transmitted to the treatment
volume based on the acceleration information and the temperature
information.
33. The apparatus of claim 32, wherein the handpiece comprises a
probe member adapted for insertion into the treatment volume
through an incision in a patient, said probe member comprising at
least a portion of the optical delivery component.
34. The apparatus of claim 33, wherein the processor is configured
to determine speed information indicative of the speed of the
handpiece based on the acceleration information; and control the
laser energy transmitted to the treatment volume based on the speed
information and the temperature information.
35. The apparatus of claim 33, wherein the processor is configured
to determine position information indicative of the position of the
handpiece based on the acceleration information; and control the
laser energy transmitted to the treatment volume based on the
position information and the temperature information.
36. The apparatus of claim 33, wherein the temperature sensor
comprises at least one selected from the group consisting of: a
thermocouple and a thermister.
37. The apparatus of claim 33, wherein the temperature sensor
comprises an infrared sensor.
38. The apparatus of claim 37, wherein the handpiece comprises a
optical sensing element configured to transmit infrared light from
the treatment volume to the infrared sensor.
39. The apparatus of claim 34, wherein the processor is configured
to compare the speed of the handpiece to a threshold value, and
inhibit the transmittal of laser energy to the treatment volume
when the speed is below the threshold value.
40. The apparatus of claim 39, wherein the temperature sensor is
configured to measure the temperature of the tissue when the
processor inhibits the transmittal of laser energy to the treatment
volume or when the processor determines that the speed of the
handpiece is below a measurement threshold speed.
41. The apparatus of claim 39, wherein the processor is configured
to compare the temperature of the tissue to a threshold value, and
inhibit the transmittal of laser energy to the treatment volume
when the temperature is above a threshold value.
42. The apparatus of claim 41, wherein the processor is configured
to repetitively, at a first repetition rate, compare the speed of
the handpiece to a speed threshold value, and inhibit the
transmittal of laser energy to the treatment volume when the speed
is below the speed threshold value; repetitively, at a second
repetition rate, compare the temperature of the tissue to a
temperature threshold value, and inhibit the transmittal of laser
energy to the treatment volume when the temperature is above the
temperature threshold value.
43. The apparatus of claim 42, wherein the first repetition rate is
greater than the second repetition rate.
44. The apparatus of claim 35, wherein the processor is configured
to determine information indicative of the temperature of tissue at
each of a plurality of positions within the treatment volume.
45. The apparatus of claim 44, wherein the processor is configured
to control the laser energy transmitted to the treatment volume
based on information indicative of the temperature of tissue at
each of a plurality of positions within the treatment volume.
46. The apparatus of claim 45, further comprising a display
configured to show a graphical depiction indicative of the
temperature of tissue at each of a plurality of positions within
the treatment volume.
47. The apparatus of claim 46, wherein the information indicative
of the temperature of tissue at each of a plurality of positions
within the treatment volume comprises, for each position, a series
of temperatures measured at a plurality of times.
48. The apparatus of claim 47, wherein the processor is configured
to, for each of the positions, calculate a running average of the
series of temperatures.
49. The apparatus of claim 48, wherein the display is configured to
display, in real time, a graphical representation of the running
averages at each of the positions.
50. The apparatus of claim 32, wherein the accelerometer comprises
a MEMs device.
51. The apparatus of claim 32, wherein the accelerometer measures
accelerations along three axes.
52. The apparatus of claim 32, wherein the accelerometer is a gyro
compensated accelerometer.
53. The apparatus of claim 32, wherein controlling the laser energy
comprises controlling at least one selected from the group
consisting of: wavelength, pulse rate, pulse duty cycle, intensity,
and fluence.
54. A laser surgical method comprising: providing a handpiece
comprising: an optical delivery component that transmits laser
energy from a source to a treatment volume; an accelerometer
configured to provide acceleration information indicative of an
acceleration of the handpiece; and a temperature sensor configured
to provide temperature information indicative of a temperature of
tissue within the treatment volume; transmitting laser energy to
the treatment volume; using the accelerometer to provide
acceleration information indicative of an acceleration of the
handpiece; using the temperature sensor to provide temperature
information indicative of a temperature of tissue within the
treatment volume; and controlling the laser energy transmitted to
the treatment volume based on the acceleration information and the
temperature information.
55. The method of claim 54, wherein the handpiece comprises a probe
member and further comprising: inserting said probe member through
an incision in a patient into the treatment volume; and delivering
laser energy to the treatment area from said probe member.
56. The method of claim 55, further comprising: determining speed
information indicative of the speed of the handpiece based on the
acceleration information; and controlling the laser energy
transmitted to the treatment volume based on the speed information
and the temperature information.
57. The method of claim 55, wherein the processor is configured to
determine position information indicative of the position of the
handpiece based on the acceleration information; control the laser
energy transmitted to the treatment volume based on the position
information and the temperature information.
58. The method of claim 56, further comprising: comparing the speed
of the handpiece to a threshold value, and inhibiting the
transmittal of laser energy to the treatment volume when the speed
is below the threshold value.
59. The method of claim 58, further comprising: using the
temperature sensor to measure the temperature of the tissue when
the processor inhibits the transmittal of laser energy to the
treatment volume or when the processor determines that the speed of
the handpiece is below a measurement threshold speed.
60. The method of claim 58, further comprising: comparing the
temperature of the tissue to a threshold value, and inhibit the
transmittal of laser energy to the treatment volume when the
temperature is above a threshold value.
61. The method of claim 57, further comprising: determining
information indicative of the temperature of tissue at each of a
plurality of positions within the treatment volume; and control the
laser energy transmitted to the treatment volume based on
information indicative of the temperature of tissue at each of a
plurality of positions within the treatment volume.
62. The method of claim 61, further comprising: displaying a
graphical depiction indicative of the temperature of tissue at each
of a plurality of positions within the treatment volume.
63. The method of claim 62, wherein the information indicative of
the temperature of tissue at each of a plurality of positions
within the treatment volume comprises, for each position, a series
of temperatures measured at a plurality of times, and further
comprising: for each of the positions, calculating a running
average of the series of temperatures; and displaying, in real
time, a graphical representation of the running averages at each of
the positions.
Description
RELATED APPLICATION(S)
[0001] The present application claims benefit of U.S. Provisional
Application Ser. No. 60/987,596, filed Nov. 13, 2007, U.S.
Provisional Application Ser. No. 60/987,617, filed Nov. 13, 2007,
U.S. Provisional Application Ser. No. 60/987,819, filed Nov. 14,
2007, U.S. Provisional Application Ser. No. 60/987,821, filed Nov.
14, 2007, U.S. Provisional Application Ser. No. 61/018,727, filed
Jan. 3, 2008, U.S. Provisional Application Ser. No. 61/018,729,
filed Jan. 3, 2008, and U.S. Provisional Application Ser. No.
60/933,736, filed Jun. 8, 2007, the contents of each of which are
incorporated by reference herein in their entirety
BACKGROUND
[0002] To improve one's health or shape, patients have resorted to
surgical methods for removing undesirable tissue from areas of
their body. For example, to remove fat tissue, some patients have
preferred liposuction, a procedure in which fat is removed by
suction mechanism because despite strenuous dieting and exercise,
some of the patients cannot lose fat, particularly in certain
areas. Alternatively, laser or other light sources has been applied
for heating, removal, destruction (for example, killing),
photocoagulation, eradication or otherwise treating (hereinafter
collectively referred as "treating" or "treatment") the tissue.
[0003] Because the treatment mechanism are implemented beneath the
skin of the patient, a clinician cannot assess the extent of the
treatment or the condition of the treated portions of the treatment
area by, for example, a type of visual aid. As such, the clinician
has no other means to determine the extent of the treatment or to
guide the instrument(s) to the untreated portions of the treatment
area except by the means of feel. In turn, it is not uncommon
during the procedure to result uneven removal of the undesired
tissue which may leave an esthetically unattractive patterning on
the patient's skin.
[0004] Further, in typical applications, there is no direct method
to ascertain the tissue type in front of the laser delivery fiber
during procedures such as laser lipolysis. The physician relies on
his knowledge of anatomy and human physiology to position the fiber
tip in the unwanted fat layer. The physician is aided by a visible
aiming beam carrying a single or multitude of wavelengths through
the delivery fiber. A skillful physician can correlate the aiming
beam visibility with the fiber tip position and depth under the
skin. However, even for a skillful physician is very hard (nearly
impossible) to determine the type of tissue in front of the fiber
tip.
[0005] Furthermore, while the tissue can be treated using laser or
light energy source as a result of absorption in the tissue of the
energy source, the surgical instruments lack a mechanism that
accounts the amount of power absorbed by the treated portions of
the treatment area. As such, the clinician can under-treat or
over-treat, resulting an incomplete removal of the tissue or
charring thereof due to overexposure.
SUMMARY OF THE INVENTION
[0006] The inventors have realized that by providing one or more
sensors for use in a medical environment where energy in directed
to target tissue (e.g. laser surgical procedure), increased safety
and ease of use may be obtained. By combining different types of
sensor inputs, a wealth of information can be provided
characterizing an ongoing medical procedure.
[0007] For example, the inventors describe herein methods and
devices that include mechanisms to detect the motion of a surgical
device used during a procedure for removing undesired tissue or
body parts.
[0008] Application of power into tissue results in a local
temperature rise according to absorbance of constituent tissues.
Propagation distance is dependent to, for example,
wavelength/tissue type. Further, each tissue type has an associated
time constant and thermal conductivity. Thus, in principle, tissue
temperature rise in vivo can be determined from knowledge of the
constituent tissues, the wavelength and power directed thereto as
long as the position of the energy delivery component of the
device, which is inserted into the treatment area is known.
[0009] According to one aspect of the present invention, the
position of the energy delivery component can be determined by
processing the acceleration of the device, which is integrated to
provide a speed feedback. Accounting the speed feedback, the device
can control the amount of the power directed to a treatment area in
relation to the value of the speed feedback. For example, the
device can stop emitting the energy directed to the treatment area
when the device is not moving or moving at a speed below a
predetermined value to prevent excessive in vivo thermal effect.
The speed feedback may also be used to control the applied dose of
energy, e.g. to maintain a fixed energy deposited in the tissue per
unit traveled.
[0010] According to another aspect of the present invention, the
position of the energy delivery component can be determined by
taking the first integration of speed (or the 2.sup.nd integration
of acceleration) to provide a position feedback of the energy
delivery component within the treatment area. Power controlling for
the position feedback application is done with a power vs.
difference-in-position algorithm. For example, each energy
discharge/shot into tissue in the treatment area is assigned a 3-D
Cartesian point on an 8 quadrant plane. Each point on the Cartesian
reference plane represents a "heat container". The heat containers
container's temperature value increments and decrements according
to energy applied or energy-in (E.sub.in), absorbance vs.
propagation distance, baseline temperature, and the time constant
and conductivity associated with the tissue type. Additional sensor
inputs such as tissue type measurement and or direct or indirect
temperature measurement can be used in conjunction with the
positional information to augment or confirm the spatial energy
distribution information.
[0011] In one aspect, a laser surgical apparatus is disclosed
including: a handpiece including an optical delivery component that
transmits laser energy from a source to a treatment volume; and an
accelerometer configured to provide information indicative of the
position of the handpiece. The apparatus includes a processor
coupled to the accelerometer and the source and controlling the
laser energy transmitted to the treatment volume; and a display.
The processor is configured to determine information indicative of
an amount of energy delivered at each of a plurality of positions
within the treatment volume based on the information indicative of
the position of the handpiece. The display is configured to display
a graphical representation indicative of the amount of energy
delivered at each of the plurality of positions within the
treatment volume.
[0012] In some embodiments, the processor is configured to control
the amount of energy delivered to the treatment volume based on
feedback from the accelerometer.
[0013] In some embodiments, the accelerometer measures acceleration
along three axes.
[0014] In some embodiments, the accelerometer is a gyro compensated
accelerometer.
[0015] In some embodiments, the graphical representation includes a
map of the treatment volume, where a plurality of points on the map
correspond to the plurality of positions within the treatment
volume, and where the a graphical quality of each of the points
depends on the amount of energy delivered at the position within
the treatment volume.
[0016] In some embodiments, the graphical representation is a three
dimensional representation.
[0017] In some embodiments, the handpiece further includes a
temperature sensor configured to provide information indicative of
the temperature of tissue at positions within the treatment volume.
The processor is coupled to the temperature sensor and is
configured to determine information indicative of the temperature
of each of a plurality of positions within the treatment volume
based on the information indicative of the position of the
handpiece and the information indicative of the temperature of
tissue at positions within the treatment volume. The display is
configured to display a graphical representation indicative of the
amount of energy delivered at each of the plurality of positions
within the treatment volume.
[0018] In one aspect, a laser surgical method is disclosed
including: providing a laser surgical device including a handpiece
including: an optical delivery component that transmits laser
energy from a source to a treatment volume; and an accelerometer
configured to provide information indicative of the position of the
handpiece. The method includes using the handpiece to transmit
laser energy from the source to a plurality of positions within the
treatment volume; using the accelerometer, providing information
indicative of the position of the handpiece; determining
information indicative of an amount of energy delivered at each of
the plurality of positions within the treatment volume based on the
information indicative of the position of the handpiece, and
displaying a graphical representation indicative of the amount of
energy delivered at each of the plurality of positions within the
treatment volume.
[0019] Some embodiments include including controlling the amount of
energy delivered to the plurality of positions within the treatment
volume based on feedback from the accelerometer.
[0020] In some embodiments, accelerometer measures acceleration
along three axes.
[0021] In some embodiments, the accelerometer is a gyro compensated
accelerometer.
[0022] In some embodiments, the graphical representation includes a
map of the treatment volume, where a plurality of points on the map
correspond to the plurality of positions within the treatment
volume, and where the a graphical quality of each of the points
depends on the amount of energy delivered at the position within
the treatment volume.
[0023] In some embodiments, the graphical representation is a three
dimensional representation.
[0024] In some embodiments, the handpiece further includes a
temperature sensor configured to provide information indicative of
the temperature of tissue at positions within the treatment volume,
and the processor is coupled to the temperature sensor. Such
embodiments include using the temperature sensor, determining
information indicative of the temperature of each of a plurality of
positions within the treatment volume based on the information
indicative of the position of the handpiece and the information
indicative of the temperature of tissue at positions within the
treatment volume, and displaying a graphical representation
indicative of the amount of energy delivered at each of the
plurality of positions within the treatment volume.
[0025] In another aspect, a laser surgical apparatus is disclosed
including: a handpiece including: an optical delivery component
that transmits laser energy from a source to a treatment volume;
and an accelerometer configured to provide information indicative
of acceleration of the handpiece along three axes. The apparatus
includes a processor coupled to the accelerometer and the source
and controlling the laser energy transmitted to the treatment
volume based on feedback from the accelerometer.
[0026] Some embodiments include a gyroscope configured to provide
information indicative of the spatial orientation of the handpiece,
and where the processor is coupled to the gyroscope and is
configured to control the laser energy transmitted to the treatment
volume based on feedback from the accelerometer and the
gyroscope.
[0027] In some embodiments, the processor is configured to
determine information indicative of an absolute position of the
handpiece based on the information indicative of acceleration of
the handpiece along three axes, and the information indicative of
the spatial orientation of the handpiece.
[0028] In some embodiments, the processor is configured to
determine information indicative of a speed of the handpiece based
on the information indicative of acceleration of the handpiece
along three axes; and control the laser energy transmitted to the
treatment volume based on feedback using the information indicative
of the speed of the handpiece.
[0029] In some embodiments, the information indicative of
acceleration of the handpiece along three axes includes, for at
least one axis, a signal having an amplitude which depends on the
acceleration of the handpiece along the axis,
[0030] In some embodiments, the processor is configured to
selectively block low frequency components of the signal prior to
integrating the signal to determine information indicative of a
speed of the handpiece along the respective axis. In some
embodiments, the processor is configured to determine the speed of
the handpiece along each of the three axes based one information
indicative of acceleration of the handpiece along three axes;
determine a weighted average speed of the handpiece by calculating
a weighted average of the speeds of the handpiece along each of the
three axes; and control the laser energy transmitted to the
treatment volume based on feedback using the weighted average speed
of the handpiece.
[0031] In some embodiments, the handpiece includes a probe member
for insertion into the treatment volume, the probe member extending
along a probe member axis, the accelerometer is configured to
provide information indicative of acceleration along each of the
three axes, one of the three axes being substantially parallel to
the probe member axis; and the processor is configured to
determined the weighted average speed of the handpiece by
calculating a weighted average of the speeds of the handpiece along
each of the three axes, where the axis substantially parallel to
the probe member axis is given greater weight that the other
axes.
[0032] In another aspect, a laser surgical method is disclosed
including: providing a handpiece including: an optical delivery
component that transmits laser energy from a source to a treatment
volume; and an accelerometer configured to provide information
indicative of acceleration of the handpiece along three axes; using
the handpiece to transmit laser energy from the source to the
treatment volume; using the accelerometer, providing information
indicative of acceleration of the handpiece along three axes; and
controlling the laser energy transmitted to the treatment volume
based on feedback from the accelerometer.
[0033] In some embodiments, the handpiece further includes a
gyroscope, and the method includes using the gyroscope, providing
information indicative of the spatial orientation of the handpiece,
and further including; and controlling the laser energy transmitted
to the treatment volume based on feedback from the accelerometer
and the gyroscope.
[0034] Some embodiments include: determining information indicative
of an absolute position of the handpiece based on the information
indicative of acceleration of the handpiece along three axes, and
the information indicative of the spatial orientation of the
handpiece.
[0035] Some embodiments include: determining information indicative
of a speed of the handpiece based on the information indicative of
acceleration of the handpiece along three axes; and controlling the
laser energy transmitted to the treatment volume based on feedback
using the information indicative of the speed of the handpiece.
[0036] Some embodiments include determining the speed of the
handpiece along each of the three axes based one information
indicative of acceleration of the handpiece along three axes;
determining a weighted average speed of the handpiece by
calculating a weighted average of the speeds of the handpiece along
each of the three axes; and controlling the laser energy
transmitted to the treatment volume based on feedback using the
weighted average speed of the handpiece.
[0037] In some embodiments, the handpiece includes a probe member
extending along a probe member axis. The method further
includes:
[0038] inserting the probe member into the treatment volume;
repetitively advancing and withdrawing the probe member within the
treatment volume; using the accelerometer to provide information
indicative of acceleration along each of the three axes, one of the
three axes being substantially parallel to the probe member axis;
and determining the weighted average speed of the handpiece by
calculating a weighted average of the speeds of the handpiece along
each of the three axes, where the axis substantially parallel to
the probe member axis is given greater weight that the other
axes.
[0039] In another aspect, a laser surgical apparatus is disclosed
including: a handpiece including: a probe member including an
optical delivery component that transmits laser energy from a
source to a treatment volume, the probe member adapted for
insertion into a treatment volume through an incision in a patient;
and an accelerometer configured to provide information indicative
of the position of the handpiece relative to the incision; a
processor coupled to the accelerometer and the source and
controlling the laser energy transmitted to the treatment volume
based on the information indicative of the position of the
handpiece relative to the incision.
[0040] In some embodiments, the accelerometer is configured to
provide information indicative of a speed of the handpiece and the
processor is configured to controlling the laser energy transmitted
to the treatment volume based on the information indicative of the
speed of the handpiece.
[0041] In another aspect, a method is disclosed including providing
a handpiece including: a probe member including an optical delivery
component that transmits laser energy from a source to a treatment
volume, the probe member adapted for insertion into a treatment
volume through an incision in a patient; and an accelerometer
configured to provide information indicative of the position of the
handpiece relative to the incision. The method includes inserting
the probe member into the treatment volume through the incision;
repetitively advancing and withdrawing the probe member within the
treatment volume; transmitting laser energy to the treatment
volume; using the accelerometer to provide information indicative
of the position of the handpiece relative to the incision; and
controlling the laser energy transmitted to the treatment volume
based on the information indicative of the position of the
handpiece relative to the incision.
[0042] Some embodiments include: using the accelerometer to provide
information indicative of a speed of the handpiece; and controlling
the laser energy transmitted to the treatment volume based on the
information indicative of the speed of the handpiece.
[0043] In another aspect, a laser surgical apparatus is disclosed
including: a handpiece including: an optical delivery component
that transmits laser energy from a source to a treatment volume; an
accelerometer configured to provide acceleration information
indicative of an acceleration of the handpiece; and a temperature
sensor configured to provide temperature information indicative of
a temperature of tissue within the treatment volume. The apparatus
includes a processor coupled to the accelerometer, the temperature
sensor, and the source and configured to control the laser energy
transmitted to the treatment volume based on the acceleration
information and the temperature information.
[0044] In some embodiments, the handpiece includes a probe member
adapted for insertion into the treatment volume through an incision
in a patient, the probe member including at least a portion of the
optical delivery component.
[0045] In some embodiments, the processor is configured to
determine speed information indicative of the speed of the
handpiece based on the acceleration information; and control the
laser energy transmitted to the treatment volume based on the speed
information and the temperature information.
[0046] In some embodiments, the processor is configured to
determine position information indicative of the position of the
handpiece based on the acceleration information; and control the
laser energy transmitted to the treatment volume based on the
position information and the temperature information.
[0047] In some embodiments, e the temperature sensor includes at
least one selected from the group consisting of: a thermocouple and
a thermister.
[0048] In some embodiments, the temperature sensor includes an
infrared sensor.
[0049] In some embodiments, the handpiece includes a optical
sensing element configured to transmit infrared light from the
treatment volume to the infrared sensor.
[0050] In some embodiments, the processor is configured to compare
the speed of the handpiece to a threshold value, and inhibit the
transmittal of laser energy to the treatment volume when the speed
is below the threshold value.
[0051] In some embodiments, the temperature sensor is configured to
measure the temperature of the tissue when the processor inhibits
the transmittal of laser energy to the treatment volume or when the
processor determines that the speed of the handpiece is below a
measurement threshold speed.
[0052] In some embodiments, the processor is configured to compare
the temperature of the tissue to a threshold value, and inhibit the
transmittal of laser energy to the treatment volume when the
temperature is above a threshold value.
[0053] In some embodiments, the processor is configured to
repetitively, at a first repetition rate, compare the speed of the
handpiece to a speed threshold value, and inhibit the transmittal
of laser energy to the treatment volume when the speed is below the
speed threshold value; and repetitively, at a second repetition
rate, compare the temperature of the tissue to a temperature
threshold value, and inhibit the transmittal of laser energy to the
treatment volume when the temperature is above the temperature
threshold value.
[0054] In some embodiments, the first repetition rate is greater
than the second repetition rate.
[0055] In some embodiments, the processor is configured to
determine information indicative of the temperature of tissue at
each of a plurality of positions within the treatment volume.
[0056] In some embodiments, processor is configured to control the
laser energy transmitted to the treatment volume based on
information indicative of the temperature of tissue at each of a
plurality of positions within the treatment volume.
[0057] Some embodiments including a display configured to show a
graphical depiction indicative of the temperature of tissue at each
of a plurality of positions within the treatment volume.
[0058] In some embodiments, the information indicative of the
temperature of tissue at each of a plurality of positions within
the treatment volume includes, for each position, a series of
temperatures measured at a plurality of times.
[0059] In some embodiments, the processor is configured to, for
each of the positions, calculate a running average of the series of
temperatures.
[0060] In some embodiments, the display is configured to display,
in real time, a graphical representation of the running averages at
each of the positions.
[0061] In some embodiments, the accelerometer includes a MEMs
device.
[0062] In some embodiments, the accelerometer measures
accelerations along three axes.
[0063] In some embodiments, the accelerometer is a gyro compensated
accelerometer.
[0064] In some embodiments, controlling the laser energy includes
controlling at least one selected from the group consisting of:
wavelength, pulse rate, pulse duty cycle, intensity, and
fluence.
[0065] In another aspect, a laser surgical method is disclosed
including: providing a handpiece including: an optical delivery
component that transmits laser energy from a source to a treatment
volume; an accelerometer configured to provide acceleration
information indicative of an acceleration of the handpiece; and a
temperature sensor configured to provide temperature information
indicative of a temperature of tissue within the treatment volume.
The method includes transmitting laser energy to the treatment
volume; using the accelerometer to provide acceleration information
indicative of an acceleration of the handpiece; using the
temperature sensor to provide temperature information indicative of
a temperature of tissue within the treatment volume; and
controlling the laser energy transmitted to the treatment volume
based on the acceleration information and the temperature
information.
[0066] In some embodiments, e the handpiece includes a probe member
and the method includes: inserting the probe member through an
incision in a patient into the treatment volume; and delivering
laser energy to the treatment area from the probe member.
[0067] Some embodiments include: determining speed information
indicative of the speed of the handpiece based on the acceleration
information; and controlling the laser energy transmitted to the
treatment volume based on the speed information and the temperature
information.
[0068] In some embodiments, the processor is configured to
determine position information indicative of the position of the
handpiece based on the acceleration information; and control the
laser energy transmitted to the treatment volume based on the
position information and the temperature information.
[0069] Some embodiments include: comparing the speed of the
handpiece to a threshold value, and inhibiting the transmittal of
laser energy to the treatment volume when the speed is below the
threshold value.
[0070] Some embodiments include: using the temperature sensor to
measure the temperature of the tissue when the processor inhibits
the transmittal of laser energy to the treatment volume or when the
processor determines that the speed of the handpiece is below a
measurement threshold speed.
[0071] Some embodiments include: comparing the temperature of the
tissue to a threshold value, and inhibit the transmittal of laser
energy to the treatment volume when the temperature is above a
threshold value.
[0072] Some embodiments include: determining information indicative
of the temperature of tissue at each of a plurality of positions
within the treatment volume; and controlling the laser energy
transmitted to the treatment volume based on information indicative
of the temperature of tissue at each of a plurality of positions
within the treatment volume.
[0073] Some embodiments include displaying a graphical depiction
indicative of the temperature of tissue at each of a plurality of
positions within the treatment volume.
[0074] In some embodiments, the information indicative of the
temperature of tissue at each of a plurality of positions within
the treatment volume includes, for each position, a series of
temperatures measured at a plurality of times. The method includes,
for each of the positions, calculating a running average of the
series of temperatures; and displaying, in real time, a graphical
representation of the running averages at each of the
positions.
[0075] Various embodiments may include any of the features
described above, alone or in combination.
BRIEF DESCRIPTION OF THE DRAWINGS
[0076] The foregoing will be apparent from the following more
particular description of example embodiments of the invention, as
illustrated in the accompanying drawings in which like reference
characters refer to the same parts throughout the different views.
The drawings are not necessarily to scale, emphasis instead being
placed upon illustrating embodiments of the present invention.
[0077] FIG. 1 is a schematic of a laser surgical system
[0078] FIG. 1A is an exploded view an embodiment of the
accelerometer in a device of the present invention;
[0079] FIG. 2 illustrates a device of the present invention applied
to a treatment area during a treatment;
[0080] FIG. 3A shows a feature in an embodiment of the device
translating acceleration in one, two, or three axes and FIG. 3B
shows an embodiment of the accelerometer mounted on to a device of
the present invention;
[0081] FIG. 4 is a schematic illustration of a filter and an input
amplifier in an embodiment of a translator processing circuit in
the present invention;
[0082] FIG. 5 is a schematic diagram for total speed estimation in
the speed vs. power application;
[0083] FIGS. 6A and 6B illustrate a mode of power output to reduce
thermal shock to a portion of the treatment area and to provide a
more even energy deposition throughout the treatment area;
[0084] FIG. 7 is a graph illustrating minimum speed vs. power
curve;
[0085] FIG. 8 is a graph illustrating the speed of the device in
terms of power output and repetition rate of pulses by the
device;
[0086] FIG. 9 is a graph illustrating offset speed vs. power
curve;
[0087] FIG. 10 illustrates a mode of plotting three-axis positions
in a three-dimensional Cartesian plane in the power vs.
difference-in-position application;
[0088] FIG. 11 illustrates a two-dimensional map of a treatment
area that represents the treated and untreated portions
thereof;
[0089] FIGS. 12A-12D illustrate overlapping pulses and the mode of
accounting such overlapping pulses for the map of the treatment
area;
[0090] FIGS. 13A-13C graphs illustrating adiabatic temperature rise
in the treatment area by 1064 nm, 1320 nm, and 1400 nm sources,
respectively;
[0091] FIG. 14 illustrates a three-dimensional coordinate including
a physical node within an interstitial target and a plot of
E.sub.in vs. propagation distance.
[0092] FIG. 15 illustrates an embodiment of a surgical system that
includes embodiments of a device and a photodetector sensor
pad;
[0093] FIG. 16 is a graph illustrating multiple wavelengths used in
the doping beam; and
[0094] FIG. 17 illustrates an embodiment of a user interface
display that is in communication with a photodetector sensor
pad.
[0095] FIG. 18 shows a surgical device featuring a thermal
sensor.
[0096] FIG. 19 shows a surgical device featuring a thermal
sensor.
[0097] FIG. 20 shows embodiments of surgical devices featuring a
thermal sensor.
[0098] FIG. 21 shows a feedback loop for controlling a surgical
device.
[0099] FIG. 22 shows a feedback loop for controlling a surgical
device.
[0100] FIG. 23 shows a schematic illustrating temperature-position
mapping for a surgical device.
[0101] FIG. 24 shows a surgical device featuring an IR thermal
sensor.
[0102] FIG. 25 shows a surgical device featuring an IR thermal
sensor.
[0103] FIG. 26 shows a graph of transmission properties of
anti-reflection coated ZnSe.
[0104] FIG. 27 shows a tissue type sensor.
[0105] FIG. 28 shows a tissue type sensor.
[0106] FIG. 29 shows a tissue type sensor featuring a sense
waveguide.
[0107] FIG. 30 shows a dual color tissue type sensor.
[0108] FIG. 31 shows an electronic circuit for use in a tissue type
sensor.
[0109] FIG. 32 shows an electronic circuit for use in a tissue type
sensor.
[0110] FIG. 33 shows a response curve for a color
photodetector.
DETAILED DESCRIPTION
[0111] A description of example embodiments of the invention
follows.
[0112] FIG. 1 shows a laser surgical system 10 featuring several
safety and control features of the type described herein. System
includes a handpiece 12 adapted to be handheld by a clinician or
other operator, and to deliver therapeutic laser energy from laser
source 14 to a treatment area (e.g. via an optical fiber).
Controller 15 operates to control the delivery of therapeutic laser
energy, e.g. by allowing or inhibiting the transmittal of light
from source 14 to the treatment area or by controlling one or more
laser parameters such as intensity, wavelength, pulse rate, etc.
Handpiece 12 includes multiple sensors 16a, 16b, and 16c of
differing types. For example, in the embodiment show sensor 16a is
an accelerometer, sensor 16b is a temperature sensor, and sensor
16c is a tissue type sensor.
[0113] Sensors 16a-c are coupled to controller 15, which can
process the outputs of the signals to determine information about
the ongoing treatment. Controller 15 can process information
measured by the sensors 16a-c and control laser 15 based on the
processed information. Information from each of the sensors 16a-c
may be used separately, or combined to provide a wealth of real
time information about the area undergoing treatment. This
information can be displayed to the clinician, or used to
automatically control laser 15 to, for example, provide a desired
dose profile across the treatment area or to inhibit laser 15 in
the event that a dangerous condition (e.g. overheating of a portion
of the treatment area) is detected. In some embodiments,
information from the sensors 16a-c may be used to confirm each
other, thereby providing enhanced reliability and safety
[0114] In some embodiments, an additional sensor 17, located
external to handpiece 12 also provides information about the area
of tissue undergoing treatment. For example, sensor 17 may be an
infrared camera or other type or IR sensor which measures the
temperature of the tissue undergoing treatment, or adjacent/related
tissue (e.g. the outer surface of the skin overlaying the tissue
undergoing treatment.).
[0115] FIG. 1A describes the device 100 for in vivo surgical
applications. The device 100 comprises an apparatus 115. The
apparatus 115 can be adapted to be handheld by a clinician (e.g., a
surgeon) and includes an energy source 105. An energy delivery
component 110 can be coupled to the energy source 105 and the
apparatus 115 to deliver energy to a treatment area (not shown).
The term "treatment area" can include any portion of a patient's
body. Examples of a treatment area can include interstitial targets
situated within a patient's body but also portions of the skin
surface. In one embodiment, the energy delivery component 110 is an
optical fiber. The energy delivery component 115, is threaded
through the apparatus 115 and a sleeve 130, reaching to the tip
135. During a procedure, the portion of the energy delivery
component 110 covered by the sleeve 130 is applied to the treatment
area. The device 100 can further include an accelerometer 120 that
is coupled to the apparatus 115 for measuring inertial
acceleration. In one embodiment, the energy delivery component 110
can be an optical fiber.
[0116] The energy source 105 can be configured to provide least one
of a suction energy, a light energy, a radiofrequency energy, sonic
9 e.g. ultrasound) energy and an electromagnetic radiation. In one
embodiment, the energy source comprises a laser light. The laser
light can comprise laser radiation. Yet in another embodiment, the
laser radiation comprises a laser pulse (e.g., Nd:YAG laser). In
this embodiment, the energy source comprises a laser. In one
embodiment, the radiofrequency energy can comprise a radiofrequency
(RF) pulse. Yet in another embodiment, the electromagnetic
radiation comprises ultraviolet (UV) light.
[0117] When a pulse is delivered to the treatment area, the
wavelength of a pulse also plays a factor to the amount of power
applied to the target. For example, a 1440 nm wavelength pulse is
more highly absorbed by, for example, fat tissue than an equivalent
power 1320 nm wavelength pulse.
[0118] In certain embodiments, the device 100 can include an
accelerometer 120 secured to the energy delivery component 110. The
accelerometer 120 can be mounted to or within the apparatus 115 in
fixed relation with respect to the energy delivery component 110.
The accelerometer 120 generates an electrical signal indicative of
the motion of the energy delivery component 110 in at least one
direction and as many as three orthogonal directions. The
electrical signal from the accelerometer 120 can be sent to a
processor 125 for controlling the energy source 105, such that the
operation of the energy source 105 is controlled, at least in part,
by the movement of the apparatus 115.
[0119] In certain embodiments, the processor 125 can be programmed
such that the energy delivery component 110 only operates when the
apparatus 115 (and thus the energy delivery component 110) is in
motion. When the accelerometer 120 indicates that the apparatus 115
and the energy delivery component 110 are stationary, the output of
the energy source 105 ceases. This provides a safety function
because it would prevent the energy delivery component 110 from
delivering more than the optimal amount of the energy in rapid
succession to the same portion of the treatment area, thereby
preventing undesirable thermal damage. Furthermore, in one
embodiment, the safety function of the device 100 can include at
least a control that provides a warning feedback when the apparatus
115 is moving below a critical minimum speed. Alternatively or in
combination with the safety function, the device 100 can include a
control for stopping the function of the energy source 105 when the
energy delivery component 110 is moving below a critical minimum
speed.
[0120] In certain embodiments, the energy source emits a beam,
which can be pulsed. For example, if the energy source delivers a
laser light, the energy source is enabled to control the rate of a
laser pulse. The energy source is configured to manipulate one or
more parameters to control the amount of the total energy directed
to the treatment area. In one embodiment, the energy source can
control a power per pulse, a pulse duration, a pulse repetition
rate, or a combination thereof. While keeping the total power
directed to the treatment area constant in a time duration, the
energy source is configured to increase or decrease the power per
pulse, the pulse duration, the pulse rate or a combination thereof.
In one embodiment, the energy source further includes a control
system that is configured to control the rate at which the energy
source generates pulses of each energy pulse in response to the
feedback provided by the accelerometer. Thus, a device (and thus an
energy delivery component) moving at a slow speed would deliver
less energy directed to the treatment area. Conversely, a device
moving at a higher speed would deliver more power. In one
embodiment, the control system can be configured to emit energy
pulses only when the device is in motion, and at a power that is
modulated in accordance with the device motion in all three axes.
In another embodiment, the energy source is enabled to control the
rate of the energy pulse in relation to: the wavelength of a pulse,
a speed of the energy delivery component, a tissue of the treatment
area, fluence setting, propagation distance, or a combination
thereof.
[0121] In certain embodiments, the device comprises a detector that
is coupled to the energy delivery component for detecting the
reaction by the treatment area in response to the treatment. In one
embodiment, a sensor can be coupled to the energy delivery
component to measure the physical change of the treatment area, in
response to the energy directed thereto. In another embodiment, a
detector can be coupled to the energy delivery component for
detecting radiation transmitted back through the energy delivery
component from the treatment area. For example, the detector
detects near infrared radiation that travels down the energy
delivery component from the treatment area, in the reverse
direction of the energy pulses. The detected near infrared
radiation can be used to monitor the temperature of the tissue in
the treatment area and to regulate the operation of the energy
source. Yet in another embodiment, the device can be programmed to
provide a warning when the detected radiation indicates that the
temperature of the tissue exceeds a pre-determined temperature. The
device can further be programmed to prohibit operation of the
energy source when the detected radiation indicates that the
temperature of the tissue exceeds a predetermined temperature. For
example, the energy source operates in a pulsed mode, and the near
infrared radiation from the treatment area is detected during the
delay period between successive treatment pulses. Even for a
continuous wave source, the treatment beam and diagnostic beam
could be modulated, such that the duty cycle of the continuous wave
treatment beam was close to unity.
[0122] FIG. 2 shows a method how a device of the present invention
can be applied. The device 200 is inserted in to a treatment area
205 (e.g., fat tissue) through an incision 210 made on the skin of
a patient. As the energy delivery component 215 is inserted and
moved further into the treatment area 205, the energy delivery
component 215 is configured to direct one or more sequential pulses
in a predetermined rate to the treatment area 205. During the
procedure, much of the absorption and heating occurs in tissue
immediately adjacent to the tip 220 of the energy delivery
component 215. As the clinician moves back and forth, the device
200, and, thus, the energy delivery component device 215 in the
treatment area 205, the energy source (not shown) provides the
energy by emitting the one or more sequential pulses, distributing
and breaking up tissue cells (e.g., fat cells).
[0123] In certain embodiments, the energy source is configured to
modulate the amount of the energy directed to the treatment area
205 in relation to the position of the energy delivery component
215. In another embodiment, the energy source is configured to
modulate the amount of the energy directed to the treatment area
205 in relation to a feedback provided by the accelerometer 230
regarding the amount of the energy delivered to a physical location
within the treatment area 205.
[0124] In one embodiment, as shown in FIGS. 3A and 3B, the device
300 includes a three-axis accelerometer 305 located in the
laser/surgical hand piece 310 and a translator processing circuit
315, which translates acceleration into speed and/or position
feedback to the operator, configured with algorithms for
manipulating power or the amount of the energy output to be
directed to the treatment area. The processing circuit 315 is
coupled to the accelerometer 305 and determines dosimetry of the
energy directed to the treatment area (not shown). The term
"dosimetry" refers to the calculation of the energy dose in matter
or tissue resulting from the exposure to the energy. As such, in
relation to the speed and/or position feedback, the device 300 can
control the power, and the amount of the energy directed to the
treatment area.
[0125] In certain embodiments, the device of the present invention
includes a processor coupled to an accelerometer for processing a
feedback from the accelerometer and for controlling the amount of
energy directed to the treatment area. In one embodiment, the
device includes a power vs. speed application. In this application,
the power directed to the treatment area is controlled in relation
to the speed feedback. The accelerometer provides outputs, which
are filtered, scaled and integrated to obtain one, two or three
axes speed feedback. When the speed feedback is provided for two or
three axes, the direct current (DC) component of the accelerometer
305 output can be filtered such that static acceleration is blocked
and only dynamic acceleration signals are sensed by the energy
delivery component. As such, when the DC component of the
accelerometer 305 is blocked, the processing circuit 315
accumulates dynamic accelerations to provide overall value for the
speed, including either + or - magnitude of the speed.
[0126] The translator processing circuit 315 includes both analog
and digital elements. The three channels of the speed feedback by
the accelerometer 305 are provided to the translator processing
circuit 315 via a filter such as a DC blocking high pass filter
(with, for example, .about.0.25 Hz cutoff) followed by an
adjustable gain input amplifier as show in FIG. 4. The input
amplifier can be also offset the filtered acceleration signals to
allow for bi-polar bi-directional acceleration feedback. Through
these means, the constant or static DC acceleration due to the
gravity is blocked, and dynamic or changing accelerations are
passed to the accelerometer to be scaled and integrated to obtain
the speed feedback. Furthermore, changes in orientation of the
device such as the one indicated as 300 in FIG. 3 or angles will
cause the static gravity acceleration vector to be re-distributed
amongst all three axes and thus to the acceleration signals because
the signals are dependent on the angles of the three axis reference
frame with respect to gravity.
[0127] In certain embodiments of the power vs. speed application,
the accelerometer is configured to provide a combined three-axis
composite speed feedback. Based on the combined speed feedback, the
power output directed to the treatment area can be then throttled
or adjusted. Because each speed signal represents velocity along a
different axis, it is not possible to simply sum the speed values
from the three axes. For example, a negative speed value in the
X-axis direction would subtract from a positive speed value in the
Y-axis or in the Z-axis. As such, to simplify processing the
accelerometers of the present invention can be configured to
provide a quasi speed total value by taking the absolute speed
value in each axis independently and then summing the absolute
values from all the axes as shown in FIG. 5. FIG. 5 demonstrates
one example how the devices of the present invention can provide
the combined three-axis composite speed feedback. In step 505 x, y,
z, the acceleration signal from each axis is measured. In steps 510
x, y, z and 515 x, y, z, the input amplifier and the acceleration
signals are offset and subsequently integrated, generating speed
values. The speed values from each axis are then converted to
absolute values in step 520 x, y, z. In step 525 x, y, z, each of
the absolute values for the speed is then weighted and summed to
provide the combined three axis composite speed feedback,
respectively. For example, the absolute value for the speed value
for the X-axis is given the most weight, contributing 85% to the
combined three axis composite speed feedback while the values of
the Y and Z axes are weighted 15% and 5%, respectively. Each axis
may be amplified differently to bias or emphasize the primary axis
of movement for the device in the given procedure. Thus, in one
embodiment, the X-axis tracks the main stroke of a procedure such
as lipolysis while lateral and depth acceleration from Y and Z axis
sensors by the accelerometer contribute less to the combined three
axis composite speed feedback. For lipolysis, the speed in the X
axis can contribute up to 80%, the Y axis up to 15%, and the Z axis
up to 5% of the combined three axis composite speed feedback. To
achieve 100% of the selected fluence (power out), the absolute
value of the speed in all three axes are added together, the sum
then must exceed the 100% fluence vs. speed threshold. If the
combined three-axis composite speed feedback is less than the 100%
threshold, the power out is reduced linearly in relation to the
speed.
[0128] In certain embodiments, the power vs. speed feedback
application can include a processor that control an energy source
(e.g., the component labeled as 215 in FIG. 2) to deliver the
energy to the treatment area with a direction-based power output
routine. With the direction-based power output routine implemented,
the energy source emits varied amounts of the energy in relation to
the direction which a device of the present invention moves. Such a
processor is applied to evenly deliver the energy to portions of
the treatment area. For example, during the forward stroke 605, 67%
of the total stroke energy is deposited as shown in FIG. 6A. In
FIG. 6B, the return stroke 610 deposits the remaining 33% of the
total power. The idea is that some cooling/thermal dispersion time
is allowed before a subsequent shot. The result is to reduce the
thermal shock (fast .DELTA.T) to the treatment area 615 while
providing a more even energy deposition throughout the portion of
the treatment area. Furthermore, the direction-based power output
routine can be applied to side-to-side strokes.
[0129] With a power vs. speed application, the clinician can know
whether and how fast the energy delivery component is moving but
the clinician cannot know where the energy delivery component is
moving exactly. For example, the clinician may return to the
treated portion of the treatment area repeatedly (e.g., moving
along the X-axis back and forth only with no speed in the Y- and
Z-axes). In such case, the speed feedback allows maximum power
output as long as the X-axis speed exceeds the minimum speed vs.
100% fluence limit. In one embodiment of the processor or the
translator processing circuit, the processor or the translator
processing is configured with an algorithm that limits the power
directed to the treatment area in relation to the speed of the
energy delivery component. With such algorithm, safety is greatly
enhanced. Injuries due to excessive dwell time are easily
prevented, and ease of learning by the operator for the optimum
tempo by the device of the present invention with the power vs.
speed application is enhanced. In another embodiment for safety
measures, the devices of the present invention can be configured
with audio feedbacks that indicate various conditions of the device
and/or the treatment area. The audio feedbacks can indicate, for
example: out of power, excessive temperature increase at a portion
of the treatment area, proximity detection of un-targeted tissues
(e.g., as determined by probe/doping beam remittance & or
reflectance photo-detector) and adverse conditions (e.g., bleeding,
charring).
[0130] In certain embodiments, the power vs. speed application
further includes a processor that implement a power limiting
algorithm. The algorithm can limit or throttle power out such that
the energy/unit volume of the treatment area does not exceed safe
thermal limits. Variables for determining how much power is safe in
relation to at least one of the following: wavelength, power
setting, tissue type (e.g., absorbance by the tissue), propagation
distance and repetition rate. For example, as described in FIG. 6,
a basic curve would require twice the minimum speed for a 2 Hz
setting as compared to a 1 Hz setting because a power output is
doubled at the 2 Hz setting. A different slope for each repetition
rate is indicated in FIG. 8. FIG. 8 illustrates that the power
directed to the treatment area and/or the repetition rate of pulses
is adjusted in relation to the speed of the device. The minimum
speed curve is to prevent excessive tissue temperature rise based
on estimates of at least one of the following: applied energy,
tissue absorbance, cool down time, and hand piece travel speed.
Furthermore, a slope correction factor can be derived from each
wavelength and/or each tissue type.
[0131] In one embodiment of the power limiting algorithm, the
device can include an energy source that is configured to modulate
the amount of the energy emitted when the energy delivery component
is within a predetermined distance from the point of entry into the
treatment area. Referring back to FIG. 2, when the tip 220 revisits
the physical location that has been already treated, the energy
source (not shown) is configured to modulate the amount of the
energy delivered to the respective portions of the treatment area
so that the already treated portions are not burned but optimally
treated with an appropriate amount of the energy. For example, the
tip 220 comes in contact with the portions at the physical location
235 near the incision 210 more frequently than the ones in the
physical location 240, which are relatively far from the incision
210. Therefore, if the portions of the physical location 235 get
pulsed with the same amount of the energy every time the tip 220
makes contact, these portions would be burned or otherwise
overtreated in time. To prevent this type of undesired overexposure
of the energy to the portions near the incision 210, the energy
source is configured to modulate the amount of the energy delivered
to the portions within a predetermined distance from the incision
210 and put a limit on the amount of the energy directed
thereto.
[0132] In certain embodiments of the power vs. speed application,
the devices of the present invention can further include an offset
mechanism, as illustrated in FIG. 7. In one embodiment, the device
includes a laser light and the laser light can be throttled
directly by the speed of the travel of the device. The offset
mechanism allows some deviation from the speed vs. power graph
provided in FIG. 9. For example, this provides the clinician the
ability to fine tune the energy vs. speed slope within hard-coded
safe limits to suit the specific procedure. For example, the
devices can be configured to apply a negative offset to increasing
power in the power vs. speed application for a 1 Hz repetition rate
setting as indicated by the curve 905. Conversely, when a positive
offsetting is applied, the devices are configured to emit less
power as indicated by the curve 910. The laser then reduces power
in relation to the speed so that the speed of travel still
determines the percentage of the selected power to be allowed.
Obviously, the selected power would never be exceeded regardless of
the device's travel speed.
[0133] An alternative to the power vs. speed power limiting
algorithm is a power vs. difference-in-position" (.DELTA.-position)
application. In this case, translation vectors are calculated from
the difference-in-position in all three axes. These translation
vectors defines the distance and absolute speed through
three-dimensional space.
[0134] The power vs. difference-in-position power application
allows a more precise control and true energy/unit volume
temperature rise limitation. Specifically, by tracking the absolute
position of the device and simultaneously the wavelength and power
out (e.g., fat tissue absorbance) a very good estimate of local
temperature rise can be made.
[0135] By plotting three separate position tracks, acceleration
independently measured in all three axes using an accelerometer is
twice integrated to yield the precise position in three-dimensional
space of the interstitial target as shown in FIG. 10. The position
tracks in the three axes are plotted and placed on a
three-dimensional Cartesian plane 1000. The three axes converges on
one point, and the plotting of the convergence of the three axes
yields the actual position 1005 of the energy delivery component of
the device in the present invention in the target area.
[0136] Location of each shot locked to an absolute position can be
recorded throughout the procedure by creating a map of the
treatment area. A simple pixel darkening display to the operator
allows quick identification of missed or untreated areas. This
feedback allows for a more evenly distributed energy treatment.
[0137] In certain embodiments of the power vs.
difference-in-position application, the treatment area is surface
portions of the patient's skin (e.g., face). Similar to a
three-dimensional map of the interstitial target shown in FIG. 10,
a three-dimensional topographical map displaying peaks and valleys
of the skin surface portions. Prior to the treatment, the
three-dimensional topographical map is produced using a
two-dimension-to-three-dimension algorithm based on photos of the
skin surface portions. Each point on the topographical map
represents an accumulation that accounts at least one of the energy
applied or E.sub.in, absorbance vs. or propagation distance and the
time constant and continuity associated with the tissue type.
During the treatment, the three dimensional topographical map is
configured to indicate: the position of the energy delivery
component; the amount of the energy directed to the respective
portion; and/or the amount of the energy absorbed by the respective
portion.
[0138] In certain embodiments of the power vs.
difference-in-position application, the power directed to the
treatment area is controlled in relation to the position feedback
where translation is calculated from the difference in position in
all three axes. This translation vector defines the distance and
absolute speed in three-dimensional space. The translator
processing circuit that is coupled to the accelerometer for the
difference-in-position feedback application differs from the speed
feedback in that gravity can no longer be disregarded. Rather, the
direction of the gravity vector must be determined either
mathematically or by use of a gyro (e.g., the component labeled as
320 in FIG. 3) coupled to the accelerometer in the device. The
advantage of the gyro is that once aligned, at the start of a
procedure, the gyro can provide precise inclination feedback, which
allows the translator to subtract gravity and independently account
the accelerations from each of the axis to derive speed and
position. The gyro also allows for other accelerometer drift and
offset compensation.
[0139] In one embodiment of the power vs. difference-in-position
application, these position feedback values can be charted on a
three-dimensional coordinate plane and any change in position of
the energy delivery component in the three-axis coordinates. This
accounting of the position allows computation of a translation
vector that defines distance between points in a three-dimensional
coordinate plane, travel time between points or other relevant
positional data and provides absolute position as well as actual
three-dimensional speed total. Another advantage of a
three-dimensional coordinate plane is simplifying complex
operations such as allowing for an offset vector and distance,
rotation about any axis or mirror image management of position
data. An example of the need for mirror image translation is such
component as the apparatus 105 in FIG. 1A. The component moves in
mirror image coordinate plane relative to such component as the
energy delivery component 110, which is within the body.
[0140] The algorithm configured with a power vs.
difference-in-position application can also limit or prevent the
discharge of excessive energy into an already treated
spot/position. Thus, the clinician can pass over the same tissue
sector multiple times while the laser throttles back the power on a
pulse by pulse or millisecond basis to prevent excessive thermal
rise. The less time the clinician allows for cooling of a
previously treated area, correspondingly less energy is then
subsequently allowed. This embodiment is illustrated in FIG. 11.
While the present invention can operate two- or
three-dimensionally, for the sake of explanation, FIG. 11 shows
only a two-dimensional sectional map illustrating a treatment area
1100. As the clinician maneuvers within the treatment area 1100,
the map records all the portions that are treated with the device
1140 and provide the clinician a view of the treatment area similar
to the one shown in FIG. 11. The treatment area 1100 can be charted
and divided into different sections 1110, 1115, 1120, 1125, and
1130 representing internal body cavities or treatment areas. The
spots/positions 1105, 1106, 1107 are the ones that are already
treated with, for example, a laser pulse and the portions 1135,
1136, 1137 are yet to be treated. As the treatment proceeds, the
clinician, observing from the position based on the power vs.
.DELTA.-position application, can readily discern the treated
portions 1105, 1106, 1107 of the treatment area 1100 from the
untreated ones 1135, 1136, 1137. Thus, the clinician would then
maneuver the device 1140 and move onto to treat the untreated
portions 1135, 1136, 1137 of the treatment area 1100. In addition
to the locations of the treated portions 1105, 1106, 1107, the map
of the treatment area 1100 also shows the amount of the energy/area
directed thereto and/or the amount of the energy absorbed. For
example, the section 1130 being treated with, for example, more
laser pulses than other sections, the map would provide an feedback
indicating that the section 1130 are treated with more power/area
for than other sections and that certain portions are already
treated optimally. In one embodiment, the map of the treatment area
can include color coding. The color coding can indicate the effects
of the treatments such as the magnitude of absorbance by the
portions of the treatment area. The color coding can also indicate
intensity of the emitted pulses, for example, a solid red dot for
many shots of pulses at certain wavelength, and a weak red dot for
few shots of pulses at another wavelength.
[0141] In certain embodiments, the devices configured with a power
vs. difference-in-position application discussed herein can include
the safety features similar to ones discussed earlier with the
speed vs. power application.
[0142] In certain embodiments, the devices configured with a power
vs. difference-in-position application discussed herein can include
one or more of the processors and/or power limiting algorithms that
were discussed with respect to the power vs. speed applications,
including one for evenly distributing the energy within treatment
area, analogous to the speed feedback application as previously
discussed.
[0143] In certain embodiments, the device of the present invention
further includes a processor that accounts for overlapping pulses.
Each pulse propagates different distances and difference absorbance
depending on the wavelength of the pulse. When the series of pulses
are emitted, the wavelength absorbance and propagation distance can
be overlapped as illustrated in FIGS. 12A-12D. FIG. 12A shows an
energy delivery component 1201 inserted under a treatment area 1205
and delivered to an energy (e.g., a laser pulse) 1210. FIG. 12B
shows the radial temperature rise from the delivered energy 1210,
bringing the nearest circle to the origin of the energy 1210 being
hottest to approximately 70.degree. C. to the farthest circle at
approximately to 50.degree. C. FIG. 12C shows hotspots 1220, 1221
resulted from a series of overlapping pulses 1225, 1226, 1227. For
the purpose of accounting the amount of power delivered to a hot
spot, the resultant thermal energy absorbed at the hot spot 1220
can be simply added together. When the series of the pulses are
emitted in different wavelengths, the total energy absorbed vs.
distance of all constituent wavelengths of the pulses allows
precise prediction of tissue temperature rise. FIG. 12D depicts two
sequential and closely placed or overlapping shots (laser pulses)
with the corresponding temperature rise vs distance. Change in
temperature or .DELTA.T for individual shots can be estimated by
the adiabatic calculations, wherein the wavelength, power, target
tissue absorbance and scattering effects allow calculation of
.DELTA.T with respect to distance and direction in the target
tissue. Closely placed shot's wherein the resulting tissue .DELTA.T
zones overlap, have an additional accumulation of temperature due
to preheating from adjacently delivered shots. Further, the ratio
between the maximum .DELTA.T and minimum .DELTA.T with respect to
distance can be defined as the "differential .DELTA.Tmax". For
example, to deposit energy and cause a very even tissue heating the
"differential .DELTA.Tmax" should be minimized to provide more
consistent tissue heating.
[0144] As shown in FIGS. 13A-13C, adiabatic temperature rises when
a portion of the treatment area when exposed to 1064 nm, 1320 nm,
and 1400 nm energy delivery components (e.g., a 600 .mu.m fiber)
delivering 100 mJ are 0.2.degree. C., 0.81.degree. C., and
20.degree. C., respectively, at a 300 .mu.m radial coordinate.
[0145] In certain embodiments of the power vs.
difference-in-position application, the treatment area is an
interstitial target. Using the accelerometer that is coupled to a
device of the present invention, an area internal to the body can
be mapped, and, thereby enabling the device to navigate the
interstitial target. In one embodiment of the three-dimensional
map, the point at which the alignment is done is defined as the
origin the origin (0.sub.x, 0.sub.y, 0.sub.z) 1405, as shown in
FIG. 14. Each physical point of the three dimensional map includes
an accumulator that measures combined effect of absorbed energy
within the range of the physical node represented by the
accumulator when the energy in (E.sub.in), for example, a laser
pulse, is directed to the physical node 1410. The arrows 1415,
1416, 1417, 1418, 1419 and 1420 show the propagation distance of
the E.sub.in to the interstitial target (the vectors of E.sub.in
propagation are indicated in three axes to simplify math and
translation). Each point on the three dimensional map represents an
accumulation that accounts at least one of the energy applied or
E.sub.in, absorbance vs. or propagation distance and the time
constant and continuity associated with the tissue type. The graph
shadowing the arrows are a plot 1425 of magnitude energy vs.
distance. The numbers +1, +2, +3, -1, -2, and -3 indicate an
arbitrary distance from the physical node 1410, +1 and -1 being the
nearest. As such, the area under +1 and -1 neared the physical node
1410 provided with or absorbed the most energy, indicated by the
highest peak temperature rise 1430. Conversely, the area further
from the physical node 1410, for example +3 or -3 show the lowest
peak temperature rise 1435.
[0146] In certain embodiments, as discussed in more detail below,
implanting doping beams or other techniques could be used to
determine tissue type. For example, using 2 different wavelength
low power light-emitting diode (such as in oximetry devices) allows
us to distinguish color specific reflectivity or remittance. The
main treatment wavelength may even be one of the doping or probing
beams multiplexed into the energy delivery component. Because
tissues reflect different wavelengths based on the type, the type
of the tissue made up the physical node 1410 can be ascertained by
a doping beam during the treatment. As the device of the present
invention maneuvers within the interstitial target, the energy
source can be adjusted automatically in accordance with the tissue
type to provide a predetermined amount of the energy that is
suitable for an optimal treatment. Furthermore, in another
embodiment, the accumulator also tracks the rate of cooling at the
physical node 1410 after one or more shots of the energy. As such,
when the device returns to the physical node 1410, the energy
source can be adjusted based on the rate of cooling to determine
whether any more treatment is necessary and by how much.
[0147] The tissue discriminator or doping beam can also ascertain
the location of the device in relation to the skin. If fiber
approaches too close to the skin (from beneath), a suitable change
in reflectivity vs. color is observed thus allowing the algorithm
to shut down the laser before causing a burn, or providing a
warning to the operator. In one embodiment, the doping beam is
located at the tip of an energy delivery component and emits a beam
which is then reflected by the tissue and detected by a sensor.
[0148] The embodiment of the device described herein are provided
with an energy source that related to laser or light energy.
However, these energy sources can be substituted with suction
energy, as commonly used in lipolysis. In the embodiments with
suction energy, an accelerometer is in communication with the
suction energy source, and thus, the suction energy source can
modulate an amount of the suction energy directed to the treatment
area. Instead of having an energy delivery component (i.e., the
component 110 in FIG. 1) that threads the apparatus (115 in FIG. 1)
and the cannula (130 in FIG. 1), the cannula by itself would be
applied to remove tissue or undesired bodily parts from the
treatment area.
[0149] In certain embodiments of the present invention, a surgical
system 1500 includes a device 1510, which is analogous to the
apparatus indicated as 100, 200, 300, or the one with suction
energy, and a visual display that is in communication with the
device. In one embodiment, the visual display indicates the
position of the a component that is analogous to the energy
delivery component such as ones indicated as 315, in FIG. 3, and/or
the amount of energy absorbed by a physical point of the treatment
area. An example of the visual display is a photodetector sensor
pad 1505 as illustrated in FIG. 14. The photo-detector sensor pad
1505 is a thin sheet containing a matrix of photodetector elements
that is placed on the patient over the treatment area. In one
embodiment, the sensor pad 1505 comprises a matrix of dye-based
solar cells 1520 (DBSC) that can be fabricated using any known
means, such as conventional silk-screen printing processes. In
another embodiment, the sensor pad 1505 comprises of a matrix of
DBSCs (e.g., .about.100 1 cm by 1 cm matrix). The DBSCs are
fabricated on a flexible plastic material having metalized
electrodes printed onto the plastic material to carry signals back
to detection circuitry 1525. As shown in FIG. 15, the sensor pad
1505 is placed on the patient over the area to be treated, and
detects the physical point 1535 of the tip 1530 and laser shots
fired on a shot-by-shot basis. The sensor pad 1505 communicates the
physical point 1535 of the tip 1530 and where shots are fired back
to the laser via a data connector 1540, such as a USB connector.
This information can then be displayed on a touch-screen display to
aide the doctor during the procedure, and can also be used by the
laser control system to disable the laser if too many shots have
been fired in any one position.
[0150] As shown in FIG. 15, as the laser is fired, the location
that the laser is fired will be detected by one or a small grouping
of the photodetectors 1535 which then send x, y coordinates back to
the laser control system for display. The laser beam could also be
doped with one or several low power constant light sources, such as
light-emitting diodes, to convey the tip position back to the
clinician for proper location of the tip during treatment. As shown
in FIG. 16, the doping wavelengths could be, for example, 550 nm or
660 nm, or a combination of both. When multiple wavelengths are
used in the doping beam, the depth of the laser hand piece tip can
be determined by detecting changes in the amplitude, e.g. due to
the differential scattering of the two wavelengths, of the doping
beams.
[0151] The sensor pad 1505 can be a disposable component that is
removed from the position translation circuitry 1525 after use and
discarded. The translation circuitry 1525 can then be attached to a
new sensor pad (not shown) for use in a subsequent lipolysis
treatment.
[0152] The laser lipolysis system can include a user interface
display 1700 as shown in FIG. 17. This display 1700 includes basic
laser interface controls 1705, such as pulse width control 1710,
fluence display 1715 and controls, etc. In addition, a laser shot
location display 1700 can display the current location of the tip
(e.g., the component 1530 in FIG. 15) as well as where on the
sensor pad (e.g., the component 1505 in FIG. 15) shots have been
recorded. The shot location display preferably also indicates the
level of treatment that has occurred throughout the grid, such as
by a color-coding of the grid. This display can be used to aide the
doctor in positioning the device for the next shot and to prevent
overtreatment in any one location of the treatment area.
[0153] Thermal Sensing
[0154] The following describes in greater detail thermal sensing
techniques of the type described above, used alone, or in
conjunction with other sensor information.
[0155] Temperature sensors may be mounted on surgical devices in
any suitable fashion. For example, FIG. 18 shows a surgical probe
1800 for laser liposuction which includes an optical fiber 1810 in
a fiber cannula 182-. The optical fiber 1810 delivers treatment
light to tissue (e.g., fat tissue). The probe also includes a
suction cannula 1830 for removal of treatment by-product. A feature
of this probe is a temperature sensor 1840 integral to the suction
cannula. The temperature sensor 1840 is set back from the laser
fiber tip. In typical embodiments, this configuration avoids
localized heating of the tip of fiber 1810 and cannula 1820 leading
to false readings of tissue temperature.
[0156] During a surgical procedure, tissue temperature can be read
while holding the probe stationary (a short pause) within the
lasing field. Based on the reading, more laser energy or cooling
effort can be applied to reach the desired internal tissue
temperature. In typical applications, temperature readings will
fluctuate (e.g. if the probe is being rapidly reciprocated into and
out of the tissue). In such cases, the temperature readings may be
averaged to indicate a meaningful temperature.
[0157] In various embodiments, any suitable temperature sensor may
be included with any of a variety of surgical probe types. For
example, FIG. 19 shows a surgical probe for laser liposuction
featuring a separate, stainless steel cannula 1910 for the
temperature sensor 1920. The temperature sensor 1920 resides in the
tip of the cannula 1910, and one or more wires 1930 run up through
the cannula 1910, into a hand piece 1940. The wires 1930 extend
from the end of the hand piece 1940 and can be connected to a
monitor or processing unit.
[0158] FIG. 20 shows an embodiment of a laser surgical probe 2000
which, unlike the embodiments shown immediately above, does not
include a suction cannula. The probe includes 2000 an optical fiber
2010 for delivering treatment light placed in an inner cannula 2020
(e.g. a standard 600 .mu.m cannula). A larger outer cannula 2030
surrounds the inner cannula 2020. A temperature sensor 2040 (e.g. a
thermocouple junction) is located near the tip of the outer cannula
2030. The sensor 2040 and connecting wires extending therefrom are
thermally and electrically isolated from the inner cannula 2020.
For example, as shown in the lower portion of the figure, the
sensor 2040 and wires may be surrounded by a thermally and
electrically insulating material jacket 2050. In some embodiments,
the sensor tip, wires, and insulating jacked may be autoclavable.
In one embodiment, the thermister is bonded and housed to the
cannula's outer surface by being blanketed in a (autoclavable,
biocompatible) heat shrink.
[0159] In various embodiments, the use of a thermistor or
thermocouple located within or adjacent to the cannula tip provides
tissue temperature feedback to the laser. Tissue temperature
feedback allows the possibility of closed loop tissue temperature
control wherein the laser output (power, pulse rate, wavelength
etc.) may be controlled (e.g. modulated) to effect a desired tissue
temperature profile for a given procedure. For example, deep "fat
busting" procedures typically place the cannula tip well out of
range of surface temperature feedback techniques such as an IR
camera. It is easy to unintentionally overheat deep tissue layers
(e.g. beyond the temperature required for optimum safe lipo
disruption). Excessive deep heating is associated with various
deleterious side effects such as necrosis of blood vessels, or even
thermal damage to adjacent tissue layers (muscle, fascia, etc). By
employing a closed loop temperature management system optimum
tissue temperatures can be maintained, simplifying the procedure
for the clinician and providing improved efficacy with enhanced
safety.
[0160] Another example of closed loop temperature management
benefits is in skin tightening procedures where the cannula tip is
placed proximal to the sub dermal layer. In essence the laser heats
fat adjacent to these deeper dermal areas and said heat acts on the
entire dermis to affect so called collagen remodeling (skin
tightening). In some applications, a difficulty is that thermal
conduction through dermal layers (to effect skin tightening) varies
greatly based on skin type and thickness. Thermal gradients from
deep dermis to epidermal layers may vary considerably. Thus it is
possible to over heat deeper sub-dermal areas while effecting
optimum surface temperatures. This may cause vascular damage and
other side effects. With closed loop thermal control of deeper or
sub dermal layers, a compromise between optimum epidermal
temperature and sub dermal temperatures can be made.
[0161] For various applications, the optimum time constant
(response rate) of any tissue contact temperature measuring device
may vary. A faster response time has the advantage of actively
measuring tissue temperature throughout the surgeon's treatment
stroke. To accomplish this, the thermal mass of the thermistor or
thermocouple should be reduced or minimized. Another possibility is
to measure the treatment stroke length (e.g. using an accelerometer
to measure a sign change in the velocity of the probe), divide the
treatment stroke into near, mid and far "ranges" and then sample
average temperature for the period the cannula tip is present in
each range. This allows a slower response time thermal couple to
generate a relatively precise average temperature feedback signal
for each of the near, mid and far range areas. Said feedback can
then be used by the laser to adjust or even out temperature
accumulation through each "range" of the cannula stroke. This
approach compensates for poor clinician technique.
[0162] As shown in FIG. 21, in some embodiments, the closed loop
control 2100 consists of a temperature control loop where a
temperature error signal is derived by a summation block/difference
amplifier and laser average power (or, equivalently, for pulsed
lasers, variable repetition rate) acts as a limit value. Desired
final tissue temperature is selected as "temperature command". When
summed with the temperature feedback from the cannula thermister a
temperature error term results. This error is then gained
(amplified) and compensated, the result of which is then clamped by
the laser power/repetition rate setpoint limiter. The resulting
output acts as a laser power, or laser repetition rate command.
Operation is such that once the tissue temperature reaches the
temperature command, laser output is inhibited. Regardless of
temperature, the laser will not exceed the laser power/rep rate
limit value.
[0163] As shown in FIG. 22, in some embodiments, control loop 2200
includes an outer tissue temperature loop combined with an inner
laser power vs. speed (or velocity) laser control loop. Using the
techniques described in detail above, speed feedback is provided by
an accelerometer, e.g. mounted to the cannula hand piece or
otherwise integrated with the surgical probe. The inner speed vs.
power loop acts to limit laser power during instantaneous hand
piece dwell (motion stoppage) thereby providing a convenient method
to inhibit the laser when the hand piece stops moving, such that a
more precise tissue temperature measurement may be made by the
cannula thermister. Additionally, the speed vs. power or inner
control loop prevents very rapid buildup of localized tissue
temperature proximal to the fiber tip which could otherwise occur
during a dwell period.
[0164] In some embodiments, this technique also allows flexibility
in the placement of the thermister (relative to the tip and
distance to heated tissue), and further reduces the fast time
constant thermister requirement. In essence the power vs. speed
loop controls very rapid tissue temperature increases (e.g. due to
probe dwell), while the thermister more precisely controls the
average tissue temperature increases which occur during the
treatment process. In some embodiments, the thermister/thermocouple
may be triggered to take a temperature measurement when the
accelerometer data indicates that the handpiece is moving
sufficiently slowly compared to the time constant of the
thermister/thermocouple to allow for an accurate measurement.
[0165] The adjustable temperature command may by selected based on
the type of procedure being performed (skin tightening vs deep lipo
disruption), or it may be selected based on the body location being
treated (neck/face vs abdomen).
[0166] In some embodiments, handpiece position information derived
from the accelerometer outputs may be combined with temperature
information from the temperature sensor to provide, for example, a
temperature map (e.g. a 2D or 3D map) of the treatment area. For
example, referring to FIG. 23 A temporary 2D temperature map can be
created from the combined data of the accelerometer and the
temperature within tissue along a cannula reciprocal stroke path
along a given surgical track. This is based on the fact that the
reciprocal axis of the handpiece may be fixed in space for several
seconds, or strokes. For example, in the embodiment shown, 1
sec/stroke a typical cycle, before a new surgical track is
selected. During each one second one second, the temperature can be
sampled more than 10 times and the information of probe position
and temperature linked (t=0-3 s below) as shown in plots 2301. In
typical applications, the information will be too transient and
perhaps noisy to be useful to the clinician, but a running average
of at least three stroke cycles will create a coarse
time/temperature map 2302 of the temperature profile within the
current surgical track. In the example shown, a quick glance by the
clinician would indicate more accumulated energy/temperature 2303
near the right, incision side of the surgical track.
[0167] The change in direction of the handpiece can be sampled
since the speed goes to zero. This concept works if the strokes
only stop on the extreme ends and not within the stroke.
[0168] In some embodiments, the thermister or thermocouple may be
replaced by other types of temperature sensors. For example, FIG.
24 shows an embodiment of a surgical laser waveguide 2400 which
incorporates IR temperature sensing of tissue adjacent to the
treatment waveguide/fiber tip 2410. An IR waveguide 2420 (e.g. a
ZnSe IR fiber) is bundled with the surgical waveguide 2430 in an
over-jacket 2440. In the example shown, a two sensor IR
photodetector assembly 2450 is located in the hand piece 2460
adjacent to the treatment beam focus assembly 2470. Portions of
light from the IR waveguide at two distinct wavelengths are
separated and directed respectively to the two IR sensors using,
for example, a dichroic beamsplitter 2480. Signals from the
detectors are compared differentially to increase sensitivity and
reject errors due to the "sense waveguide" transmission variables
or characteristics.
[0169] The signals from the IR sensors are processed to obtain
temperature information about the tissue under treatment. IR
temperature monitoring provides tissue temperature feedback to the
laser (which would adjust energy deposition based on observed
tissue temperatures. In various embodiments, this could include a
simple maximum temperature safety limit, or feedback could allow
closed loop temperature control of tissues. In either case the
laser takes feedback from the IR sensor and then adjusts laser
output power (closed loop) to achieve the selected tissue
temperature.
[0170] In some embodiments, the surgical waveguide itself can
collect IR light from the treatment area during treatment to
provide IR tissue temperature sensing. However, for some
applications, such a waveguide or fiber would be required to pass
high energy lasers in the 532 to 1550 nm wavelengths (treatment
wavelengths) and also IR wavelengths of 3-14 .mu.m, e.g. 3-5 .mu.m
or 8-12 .mu.m (for temperature sensing and feedback). In some
embodiments, this may be an unwanted requirement. FIG. 25 shows an
example of a device 2500 which avoids this requirement by employing
a dual fiber approach. As with the systems described above, light
at a treatment wavelength is delivered via a waveguide 2510 (e.g. a
stiffened fiber) suitable for surgical use without a cannula. The
treatment waveguide 2510 is surrounded by and coaxial with an IR
waveguide 2520 (.e.g. a ZnSe cylinder or tube). As described above,
the treatment waveguide 2510 is coupled to a treatment fiber 2530
which delivers light from a treatment source. The coupling is
accomplished using a focus assembly 2540 in a connector 2550
connected to the back of a hand piece. As shown, the connector also
includes and IR pass filter ring 2560 (to filter out stray
treatment light) and IR detector ring 2570 (e.g., an annular array
of IR photodetectors), aligned with the IR waveguide tube 2520. The
IR sensor ring produces electrical signals in response to incident
IR light. These signals are passed to a processor, which operates
to determine tissue temperature information and provide feedback to
the treatment laser, as described above.
[0171] As described above, in various embodiments, IR light from a
treatment area is propagated to an IR detector assembly via optics
suitable for in vivo temperature monitoring. These optics may
include, for example, coated ZnSe or Germanium rods or tubes, or
certain IR transmissive plastics or even photonic waveguides (the
IR transmission characteristics of AR coated ZnSe are shown in FIG.
26). Although several examples of IR optics are presented, it is to
be understood that other suitable materials, geometries, and
configurations may be used.
[0172] The temperature information acquired using the above
described IR sensing techniques may be used in place of the
thermister/thermocouple derived information in any of the
techniques described above.
[0173] In some embodiments, a surgical probe is disclosed with a
temperature sensor attached to cannula tip for purpose of measuring
cannula temperature and shutting down laser should cannula become
overheated. In various embodiments, the temperature sensor may
include a negative temperature coefficient NTC or positive
temperature coefficient PTC thermister or even IR
photodetectors.
[0174] Some embodiments employ control method or algorithm where a
temperature feedback signal from a temperature sensor is used to
adjust laser output power by means of an error amplifier and
compensation circuits.
[0175] Some embodiments employ a method or control algorithm that
limits the temperature measured at the cannula tip for purpose of
limiting laser output based on combined tissue and cannula tip
temperature rise.
[0176] Some embodiments employ a method or control algorithm that,
based on the temperature measured at a cannula tip of a laser
surgical probe, limits laser output based on combined tissue and
cannula tip temperature rise.
[0177] Some embodiments employ a method or control algorithm which
adjusts the relative power of independent wavelengths of a
multiplexed laser treatment pulse to effect a change in tissue
temperature rise or treatment area to improve the homogenous
deposition of energy and also temperature rise. Since penetrating
depths vary for different laser wavelengths, simply adjusting the
ratio of composite wavelengths adjusts the dimensions of the
treatment space or treatment area.
[0178] Tissue Type Discrimination
[0179] An exemplary probe beam injector 2700 with reflectivity and
remittance color sensor is shown in FIGS. 27 and 28. A tissue
treatment beam (in this example, with a wavelength of 1064 nm) is
propagated from the output coupler (OC) of a treatment beam
resonator cavity to a focus assembly 2720 via a polarized beam
splitter 2730. The polarizer/beamsplitters are transparent to the
1064 nm treatment beam yet act as polarizers to one or more
probe/doping beams. Accordingly, the probe beam sources at one or
more wavelengths are coupled in to the path of the treatment beam,
directed to the focus assembly 2720, propagated down a fiber 2740
or waveguide to an output tip 2750, and directed to tissue of
interest. Similarly, reflected/remitted probe light from the tissue
is collected and propagates back along the fiber 2740 or waveguide
from the output tip 2750 and back through the focus assembly 2720
and is separated out from the path of the treatment beam and
directed to one or more color photodetectors 2760. The
photodetectors may include filters for filtering out stray
treatment light and/or to distinguish between multiple probe light
wavelengths (i.e. colors). Signals from the photodetectors (e.g.
color and intensity), are processed, e.g. as described below, to
characterize tissue and determine treatment (e.g., treatment beam
intensity, pulse duration, etc.). For example, in laser lipolysis
applications, if hidden vascular tissue, or other tissue unsuited
for treatment is identified, the treatment laser is directed not to
fire.
[0180] FIGS. 29 and 30 show examples of laser systems with tissue
type determination featuring dual waveguides. As in the system
described above, doping/probe light at multiple wavelengths/colors
(as shown, 532 nm green and 635 nm red light) are coupled into the
path of a treatment beam (e.g. using dichroic elements 2710 such as
mirrors and/or beam combiners/splitters), and propagated down a
treatment waveguide or fiber 2720 to a treatment area 2730.
However, unlike the systems above, a second "sense" waveguide or
fiber 2740 is included with the treatment fiber, e.g. in a cannula
2750 or catheter inserted into the patient. The sense fiber 2740
collects reflected/remitted light from tissue of interest, and
propagates it back to a focus assembly 2760 and on to a color
photodetector 2770 (e.g. an RGB photodetector). As with the systems
above, signals from the photodetector are processed using
processing electronics 2780 (e.g. differential amplifiers, analog
to digital converters, microprocessors, etc, see below) for tissue
determination. The results of the tissue determination are fed back
to the treatments laser source 2780 (or laser source controller
2790) to control (e.g. provide or halt) treatment based on the
determined tissue type. In some embodiments, the sense fiber tip
2795 can be offset from the treatment fiber tip 2796, as shown.
[0181] In various embodiments, visible or invisible wavelengths can
be used for tissue type discrimination. (As mentioned above, in
some embodiments the diagnostic and treatment beams are a single
beam.) In some embodiments, at least 2 diagnostic wavelengths are
used, although more wavelengths will improve precision and
resolution. For example, aim-beam style low power visible lasers
(e.g. lasers with power outputs in the range of about 1-50 mW) are
readily available, low cost, and suitable for discrimination of the
major tissues of interest common to laser lipolysis. For example
human fat is yellow, fascia is white, and skin contains large
amounts of darker pigments including red, etc. In some embodiments,
the diagnostic "doping" or probe beams may be continuous wave (CW).
In some embodiments, a time multi-plexed or pulsed combination of
different wavelengths may also be used.
[0182] In some embodiments, it is possible to build a tissue type
determination system based on a single wavelength diagnostic beam.
The single wavelength is chosen so that there is a large difference
in the absorption coefficient of the targeted lipids and the all
the other tissues that are not targeted. However, such system
heavily relies on a predetermined backscatter coupling efficiency.
That is the total efficiency of delivering the diagnostic beam to
the tissue in front of the tip, collecting the backscattered
signal, and delivering the backscattered signal to a sensor in the
laser system. Any changes in the fiber delivery system (like fiber
tip contamination) would change the backscatter coupling efficiency
and decrease the reliability of a single wavelength diagnostic
system.
[0183] The reliability of the tissue type diagnostic can be greatly
improved by using a multiple wavelength diagnostic beam. Increasing
the number of wavelengths will increase the precision of the
diagnostic system and allow it, for example, to distinguish between
multiple chromophores.
[0184] As an example a two wavelength diagnostic system will be
considered. In the example the system will be assumed to
distinguish between fat (liposomes) and water. Most tissues in the
body other than fat contain over 80% water. Therefore a diagnostic
system that distinguishes between fat and water can be used to
deliver energy when the fiber tip is pointing towards fat and not
to deliver energy when the tip is pointing at any other tissue.
[0185] Although not intending to be bound by theory, the following
example illustrates the operation of a two wavelength diagnostic
system designed to determine the fat content in water environment.
For each wavelength the signal propagates from the source to the
detector. For wavelength 1 the source intensity is S.sub.1. The
total optical system and fiber transmission is T. The signal
delivered at the end of the fiber is S.sub.1T. Part of that signal
is backscattered to the fiber with efficiency B while part of it is
absorbed with efficiency A.sub.1. The signal that arrives back at
the fiber end is S.sub.1TB(1-A.sub.1). The backscattered signal is
coupled to the fiber and transmitted to the detector with
efficiency C, the detector has efficiency D.sub.1. The signal
arriving at the detector is S.sub.1TB(1-A.sub.1)CD.sub.1. It will
be assumed that if the two diagnostic wavelengths are sufficiently
close (300 nm in the IR) the backscattering efficiency B does not
depend on the wavelength or the fat content f. Then the only fat
content dependent parameter is the absorption efficiency A. If the
diagnosed tissue has an unknown fat content f, the detected signals
in the two detectors V.sub.1 and V.sub.2 for the two wavelengths
can be written as
V.sub.1=fS.sub.1TB(1-A.sub.1.sup.F)CD.sub.1+(1-f)S.sub.1TB(1-A.sub.1.sup-
.W)CD.sub.1
V.sub.2=fS.sub.2TB(1-A.sub.2.sup.F)CD.sub.2+(1-f)S.sub.2TB(1-A.sub.2.sup-
.W)CD.sub.2
where the indices 1 and two indicate wavelengths and the
superscripts F and W indicate fat and water. The two equations can
be rewritten as
V.sub.1=S.sub.1TBCD.sub.1(1-A.sub.1.sup.W)+fS.sub.1TBCD.sub.1((1-A.sub.1-
.sup.F)-(1-A.sub.1.sup.W))
V.sub.2=S.sub.2TBCD.sub.2(1-A.sub.2.sup.W)+fS.sub.2TBCD.sub.2((1-A.sub.2-
.sup.F)-(1-A.sub.2.sup.W)) (1)
The parameters independent of tissue absorption can be eliminated
by system calibration--that is by measuring the diagnostic signals
V.sub.1c and V.sub.2c from a known sample with no fat content
(f=0). The expressions for the calibration measurements are
V.sub.1c=S.sub.1TBCD.sub.1(1-A.sub.1.sup.W)
V.sub.2c=S.sub.2TBCD.sub.2(1-A.sub.2.sup.W)
The ratio of the two calibration measurements R.sub.c can be
defined as
R c = V 2 c V 1 c = S 2 TBCD 2 ( 1 - A 2 W ) S 1 TBCD 1 ( 1 - A 1 W
) ##EQU00001##
The calibration ratio may be obtained from a calibration tissue
phantom before the laser lypolisys procedure begins and stored in
the diagnostic system computer to be used in the real time tissue
determination. During the laser treatment the diagnostic system
runs the tissue determination procedure interspersed between the
treatment pulses (or in parallel with a CW treatment beam) while
the operator moves the treatment tip. The real time diagnostic
signals V.sub.1d and V.sub.2d can be expressed from (1)
V.sub.1d=S.sub.1TBCD.sub.1(1-A.sub.1.sup.W)+fS.sub.1TBCD.sub.1(A.sub.1.s-
up.W-A.sub.1.sup.F)
V.sub.2d=S.sub.2TBCD.sub.2(1-A.sub.2.sup.W)+fS.sub.2TBCD.sub.2(A.sub.2.s-
up.W-A.sub.2.sup.F)
Based on the calibration measurement the last expression can be
rewritten as
V 1 d = S 1 TBCD 1 ( 1 - A 1 W ) + fS 1 TBCD 1 ( A 1 W - A 1 F )
##EQU00002## V 2 d = R c S 1 TBCD 1 ( 1 - A 1 W ) + fR c S 1 TBCD 1
( 1 - A 1 W ) ( 1 - A 2 W ) ( A 2 W - A 2 F ) ##EQU00002.2##
The product S.sub.1TBCD.sub.1 can be expressed from the first
equation and substituted in the second
S 1 TBCD 1 = V 1 d ( 1 - A 1 W ) + f ( A 1 W - A 1 F ) ##EQU00003##
V 2 d = R c V 1 d ( 1 - A 1 W ) + f ( A 1 W + A 1 F ) 1 ( 1 - A 1 W
) + fR c V 1 d ( 1 - A 1 W ) + f ( A 1 W - A 1 F ) ( 1 - A 1 W ) (
1 - A 2 W ) ( A 2 W - A 2 F ) ##EQU00003.2##
The ratio of the two diagnostic measurements R.sub.d can be defined
as
R d = V 2 d V 1 d = R c ( 1 - A 1 W ) ( 1 - A 1 W ) + f ( A 1 W - A
1 F ) 1 + fR c ( 1 - A 1 W ) ( 1 - A 1 W ) + f ( A 1 W - A 1 F ) (
A 2 W - A 2 F ) ( 1 - A 2 W ) ##EQU00004##
[0186] The last expression can be used to express the unknown fat
content fraction
f = ( R c - R d ) ( 1 - A 1 W ) R d ( A 1 W - A 1 F ) - R c ( 1 - A
1 W ) ( 1 - A 2 W ) ( A 2 W - A 2 F ) = ( R c - R d ) R d ( A 1 W -
A 1 F ) ( 1 - A 1 W ) - R c ( A 2 W - A 2 F ) ( 1 - A 2 W ) ( 2 )
##EQU00005##
[0187] The calculated tissue fat content f can be used by the
tissue determination system based on a threshold value (for example
when f>80%) to determine if the laser should be fired or
not.
[0188] The expression for the tissue fat content (2) emphasizes the
importance of choosing at least one wavelength so that there will
be a large difference in the absorbed fractions in fat and water
and at least one of the difference terms in the denominator will be
large. One such wavelength region is 1300 to 1500 nm. A possible
choice for large absorption difference wavelength is 1440 nm. The
form of expression (2) would be simplified if the other wavelength
is chosen so that the absorbed fractions in fat and water are
nearly the same. Such wavelengths are for example around 1190,
1230, 1690 and 1730 nm. If one of the wavelengths (wavelength 1) is
chosen so that the absorbed fractions in fat and water are nearly
the same, the expression (2) for the fat content f becomes a linear
function of the ratio of the two diagnostic measurements
R.sub.d.
f = R d ( 1 - A 2 W ) R c ( A 2 W - A 2 F ) - ( 1 - A 2 W ) ( A 2 W
- A 2 F ) ( 3 ) ##EQU00006##
The expression (3) can be simplified further if the absorbed
fraction in fat is neglected in comparison to the much larger
absorbed fraction in water
f = R d ( 1 - A 2 W ) R c A 2 W - ( 1 - A 2 W ) A 2 W ( 4 )
##EQU00007##
Expression (4) can be rearranged to express the expected ratio of
the diagnostic and calibration ratios (R.sub.d and R.sub.c) as a
function of the fat content f
r t = R d R c = ( 1 - A 2 W + fA 2 W ) ( 1 - A 2 W ) ( 5 )
##EQU00008##
where r.sub.t can be interpreted as a tissue type ratio. It is
clear from equation (5) that for very low fat content f.apprxeq.0,
the diagnostic ratio is equal to the calibration ratio and the
tissue type ratio r.sub.t.apprxeq.1. As the fat content increases
(and for wavelength 2 fat having much lower absorption than water),
the tissue type ratio grows.
[0189] In some embodiments, a diagnostic system a threshold tissue
type ratio may be predetermined so that if the tissue type ratio
exceeds the threshold, the sampled tissue in front of the tip of
the delivery fiber will be considered to be fat. The threshold
tissue type ratio can be calculated, for example, using equation
(5) and absorbed fraction in water at wavelength 2. In some
embodiments, the threshold tissue type ratio can be established by
experimental measurements in excised tissue fat from fat reduction
surgery.
[0190] In some embodiments, the operation of the tissue type
determination can be greatly simplified with some loss of precision
by a specific choice of diagnostic wavelengths. One such choice is
when wavelength 1 is chosen so that water and fat have the same
absorption, for example around 1230 nm. Then wavelength 2 is chosen
so that water has nearly the same absorption and fat has a much
lower absorption
A.sub.1..sup.F=A.sub.1..sup.W=A.sup.W.apprxeq.A.sub.2.sup.W>>A.sub.-
2.sup.F. For example wavelength 2 can be chosen around 1290 nm.
Other possible combinations of wavelengths 1 and 2 can be 930 nm
and 1070 nm, 1730 nm and 1630 nm, 2320 nm and 2100 nm. For these
wavelength choices the expressions (1) for the diagnostic signals
at the two wavelengths simplify to
V.sub.1=S.sub.1TBCD.sub.1(1-A.sup.W)
V.sub.2=S.sub.2TBCD.sub.2(1-A.sup.W)+fS.sub.2TBCD.sub.2A.sup.W
The source intensity is S.sub.1 and S.sub.2 and the detector has
efficiencies D.sub.1 and D.sub.2 can be adjusted to be the same
(for example using electronics). Then the diagnostic ratio of the
two signals reduces to
.rho. d = V 2 V 1 = 1 - A W + fA W 1 - A W ##EQU00009##
Then for very low fat content the diagnostic ratio is around 1 and
it grows with increasing fat content. A threshold tissue type ratio
can be established either by calculations or by experimental
measurements in excised tissue fat from fat reduction surgery.
[0191] FIG. 31 shows an exemplary circuit 3100 for use in
processing signals detected by a color photodetector. As shown, an
MTCSiCO Integral True Color Sensor type TO39 is used as the color
photodetector. The TO 39 includes three photodiodes which each
produce photocurrents in response to light at a different frequency
(the spectral response characteristics of the respective
photodiodes are shown in FIG. 33). An amplifying circuit features a
three op amp package OPA491, configured to convert the respective
photocurrents from the TO39 into voltages. Variable resistors are
provided to selectively adjust the response of the amplifying
circuit to each of the three photocurrent "channels." As described
above, such control of detector response efficiencies can be used
to simplify tissue determination
[0192] FIG. 32 also shows an example of a differential amplifier
3200 for use in tissue type determination using the techniques
described above. The differential amplifier produces a voltage
difference across its output terminals which is representative of
the difference in photocurrent measured by each of two photodiodes
corresponding to different detected wavelengths.
[0193] It is to be understood that the light collected for tissue
type analysis may include, for example, reflected probe/doping
light, scattered or refracted probe/doping light, remitted light,
stimulated fluorescence or phosphorescence, or any other light
indicative of tissue type.
[0194] Embodiments of the present invention described herein are
directed to devices and methods that can be used in a surgical
procedures. One example of the surgical procedures is
lipolysis.
[0195] While this invention has been particularly shown and
described with references to example embodiments thereof, it will
be understood by those skilled in the art that various changes in
form and details may be made therein without departing from the
scope of the invention encompassed by the appended claims.
[0196] One or more or any part thereof of the tissue determination
techniques described above can be implemented in computer hardware
or software, or a combination of both. The methods can be
implemented in computer programs using standard programming
techniques following the method and figures described herein.
Program code is applied to input data to perform the functions
described herein and generate output information. The output
information is applied to one or more output devices such as a
display monitor. Each program may be implemented in a high level
procedural or object oriented programming language to communicate
with a computer system. However, the programs can be implemented in
assembly or machine language, if desired. In any case, the language
can be a compiled or interpreted language. Moreover, the program
can run on dedicated integrated circuits preprogrammed for that
purpose.
[0197] Each such computer program is preferably stored on a storage
medium or device (e.g., ROM or magnetic diskette) readable by a
general or special purpose programmable computer, for configuring
and operating the computer when the storage media or device is read
by the computer to perform the procedures described herein. The
computer program can also reside in cache or main memory during
program execution. The analysis method can also be implemented as a
computer-readable storage medium, configured with a computer
program, where the storage medium so configured causes a computer
to operate in a specific and predefined manner to perform the
functions described herein.
* * * * *