Adaptive control of optical pulses for laser medicine
View Patent ↗Tissue is treated by irradiating it with a sequence of optical pulses that are directed in sequence to various sites on the tissue. During the irradiation sequence, one or more tissue properties are measured at a site(s) that has already been irradiated. These measurements are used to adjust the parameters of subsequent optical pulses in the sequence.
1. A method for adaptive control of optical pulses used to irradiate tissue, comprising:
irradiating tissue with a sequence of optical pulses, the optical pulses directed in sequence to sites on the tissue;
during the irradiation sequence, making a measurement of a property of the tissue at a site already irradiated by one or more of the optical pulses; and
based on said measurement, adjusting a parameter of a subsequent optical pulse in the sequence according to an artificial intelligence algorithm.
2. The method of claim 1 wherein the step of adjusting the parameter comprises:
comparing the measurement with a predetermined value of the property; and
based on said comparison, adjusting the parameter of the subsequent optical pulse.
3. The method of claim 2 wherein the predetermined value is an end-point value of the property.
4. The method of claim 1 wherein the sequence of optical pulses is generated by laser scanning.
5. The method of claim 1 wherein the step of irradiating tissue with a sequence of optical pulses comprises:
irradiating one or more sites in the sequence of sites with multiple optical pulses.
6. The method of claim 1 wherein the step of irradiating tissue with a sequence of optical pulses comprises:
simultaneously irradiating one or more sites in the sequence of sites with multiple optical pulses.
7. The method of claim 1 wherein the parameter of the subsequent optical pulse includes a parameter selected from an energy of the optical pulse, a duration of the optical pulse, a temporal shape of the optical pulse, a spatial shape of the optical pulse, a propagation direction of the optical pulse relative to the tissue surface, a focusing characteristic of the optical pulse, a polarization of the optical pulse, and a wavelength spectrum of the optical pulse.
8. The method of claim 1 wherein the property of the tissue includes a property selected from mechanical density, electrical capacitance, dielectric constant, birefringence, opacity, optical reflectivity, absorption, extinction, elasticity, water fraction, melanin fraction, hemoglobin fraction, oxyhemoglobin fraction, and fraction of foreign matter.
9. The method of claim 1 wherein the property of the tissue includes a temperature of the tissue.
10. The method of claim 1 wherein the step of making a measurement of a property of the tissue at a site comprises:
making a measurement of a change in the property of the tissue at the site.
11. The method of claim 10 wherein the step of making a measurement of a change in the property of the tissue at the site comprises:
making a measurement of a change in the property of the tissue from before irradiation of the site by an optical pulse and after irradiation of the site by the optical pulse.
12. The method of claim 1 wherein:
the step of making a measurement of a property of the tissue at a site comprises:
making a measurement of the property at two or more sites already irradiated by optical pulses; and
taking a weighted average of said measurements; and
the step of adjusting a parameter of the subsequent optical pulse comprises:
adjusting the parameter based on the weighted average.
13. The method of claim 12 wherein:
the weighted average is an exponential weighted average.
14. The method of claim 12 wherein:
the weighted average is weighted according to time.
15. The method of claim 12 wherein:
the weighted average is weighted according to distance.
16. The method of claim 1 wherein the subsequent optical pulse is directed to the site already irradiated by one or more of the optical pulses.
17. The method of claim 1 wherein:
the step of making a measurement of a property of the tissue comprises making a measurement of two or more properties of the tissue; and
the step of adjusting the parameter comprises adjusting two or more parameters based on said measurements.
18. The method of claim 1 , wherein the parameter for the optical pulses is dithered.
19. The method of claim 1 further comprising:
determining a characteristic of the tissue based on the measurement, wherein the step of adjusting the parameter comprises adjusting the parameter in response to the determined characteristic.
20. The method of claim 1 further comprising:
determining a characteristic of the tissue based on the measurement; and
storing the determined characteristics.
21. The method of claim 20 further comprising:
irradiating tissue with a second sequence of optical pulses, the optical pulses directed in sequence to a second set of sites on the tissue;
accessing the stored characteristic of the tissue; and
adjusting a parameter of an optical pulse in the sequence in response to the accessed characteristic.
22. The method of claim 1 wherein said measurement and said irradiation by the subsequent optical pulse are separated by less than 1 second.
23. A method for adaptive control of optical pulses used to irradiate tissue, comprising:
irradiating tissue with a sequence of optical pulses, the optical pulses directed in sequence to sites on the tissue;
during the irradiation sequence, making measurements of a property of the tissue at two or more sites already irradiated by one or more of the optical pulses and taking a weighted average of the measurements; and
based on said measurements, adjusting a parameter of a subsequent optical pulse in the sequence based on the weighted average.
24. The method of claim 23 wherein the step of adjusting the parameter of a subsequent optical pulse in the sequence based on the weighted average comprises:
comparing the weighted average of the measurements of the property with a predetermined value of the property; and
based on said comparison, adjusting the parameter of the subsequent optical pulse.
25. The method of claim 24 wherein the predetermined value is an end-point value of the property.
26. The method of claim 23 wherein the sequence of optical pulses is generated by laser scanning.
27. The method of claim 23 wherein the step of irradiating tissue with a sequence of optical pulses comprises:
irradiating one or more sites in the sequence of sites with multiple optical pulses.
28. The method of claim 23 wherein the step of irradiating tissue with a sequence of optical pulses comprises:
simultaneously irradiating one or more sites in the sequence of sites with multiple optical pulses.
29. The method of claim 23 wherein the parameter of the subsequent optical pulse includes a parameter selected from an energy of the optical pulse, a duration of the optical pulse, a temporal shape of the optical pulse, a spatial shape of the optical pulse, a propagation direction of the optical pulse relative to the tissue surface, a focusing characteristic of the optical pulse, a polarization of the optical pulse, and a wavelength spectrum of the optical pulse.
30. The method of claim 23 wherein the property of the tissue includes a property selected from mechanical density, electrical capacitance, dielectric constant, birefringence, opacity, optical reflectivity, absorption, extinction, elasticity, water fraction, melanin fraction, hemoglobin fraction, oxyhemoglobin fraction, and fraction of foreign matter.
31. The method of claim 23 wherein the property of the tissue includes a temperature of the tissue.
32. The method of claim 23 wherein the subsequent optical pulse is directed to the site already irradiated by one or more of the optical pulses.
33. The method of claim 23 wherein the step of adjusting the parameter comprises:
adjusting the parameter according to an artificial intelligence algorithm.
34. The method of claim 23 wherein the step of adjusting the parameter comprises:
applying a predetermined rule to the measurement; and
adjusting the parameter according to the predetermined rule.
35. The method of claim 23 wherein:
the step of making a measurement of a property of the tissue comprises measuring two or more properties of the tissue; and
the step of adjusting the parameter comprises adjusting two or more parameters.
36. The method of claim 23 wherein the step of adjusting the parameter comprises:
adjusting the parameter according to a control algorithm.
37. The method of claim 36 wherein the step of adjusting the control algorithm includes a constraint on the adjusted parameter.
38. The method of claim 36 wherein the control algorithm dithers the parameter for the optical pulses.
39. The method of claim 23 wherein the step of adjusting the parameter comprises:
adjusting the parameter according to an algorithm selected from a moving simplex algorithm, a neural net algorithm, and a fuzzy logic algorithm.
40. The method of claim 23 further comprising:
determining a characteristic of the tissue based on the weighted average; and
storing the determined characteristics.
41. The method of claim 40 further comprising:
irradiating tissue with a second sequence of optical pulses, the optical pulses directed in sequence to a second site on the tissue;
accessing the stored characteristic of the tissue; and
adjusting a parameter of an optical pulse in the sequence in response to the accessed characteristic.
42. A method for adaptive control of optical pulses used to irradiate tissue, comprising:
irradiating tissue with a sequence of optical pulses, the optical pulses directed in sequence to sites on the tissue;
during the irradiation sequence, making a measurement of a property of the tissue at a site already irradiated by one or more of the optical pulses; and
based on said measurement, adjusting a parameter of a subsequent optical pulse in the sequence according to an algorithm selected from a moving simplex algorithm, a neural net algorithm, and a fuzzy logic algorithm.
43. The method of claim 42 wherein the step of adjusting the parameter comprises:
comparing a value of the measurement with a predetermined value of the property; and
based on said comparison, adjusting the parameter of the subsequent optical pulse according to said algorithm.
44. The method of claim 42 wherein the parameter of the subsequent optical pulse includes a parameter selected from an energy of the optical pulse, a duration of the optical pulse, a temporal shape of the optical pulse, a spatial shape of the optical pulse, a propagation direction of the optical pulse relative to the tissue surface, a focusing characteristic of the optical pulse, a polarization of the optical pulse, and a wavelength spectrum of the optical pulse.
45. The method of claim 42 wherein the property of the tissue includes a property selected from mechanical density, electrical capacitance, dielectric constant, birefringence, opacity, optical reflectivity, absorption, extinction, elasticity, water fraction, melanin fraction, hemoglobin fraction, oxyhemoglobin fraction, and fraction of foreign matter.
46. The method of claim 42 wherein the property of the tissue includes a temperature of the tissue.
47. The method of claim 42 wherein the step of making a measurement of a property of the tissue at a site comprises:
making a measurement of a change in the property of the tissue at two or more sites.
48. The method of claim 42 wherein the subsequent optical pulse is directed to the site already irradiated by one or more of the optical pulses.
49. The method of claim 42 wherein:
the step of making measurements of measuring a property of the tissue comprises making measurements of two or more properties of the tissue; and
the step of adjusting the parameter comprises adjusting two or more parameters based on said measurements according to said algorithm.
50. The method of claim 42 further comprising:
determining a characteristic of the tissue based on the measurement, wherein the step of adjusting the parameter comprises adjusting the parameter in response to the determined characteristic according to said algorithm.
51. The method of claim 42 further comprising:
determining a characteristic of the tissue based on the measurement; and
storing the determined characteristic.