Melanin Ablation Guided by Stepwise Multi-Photon Activated Fluorescence

• US 20170143423A1
• Filed: 07/02/2015
• Published: 05/25/2017
• Est. Priority Date: 07/03/2014
• Status: Active Grant

• Current Assignee: Zhenhua Lai
• Original Assignee: Northeastern University
• Inventors: LAI, Zhenhua
• Granted Patent: US 10,507,059 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 18/203 applying laser energy to the outside of the body
• CPC Class Codes: A61B 2018/00452 Skin
• CPC Class Codes: A61B 2018/00476 Hair follicles
• CPC Class Codes: A61B 2018/00577 Ablation
• CPC Class Codes: A61B 2018/00785 Reflected power
• CPC Class Codes: A61B 2018/20359 by movable mirrors, e.g. galvanometric
• CPC Class Codes: A61B 5/0071 by measuring fluorescence emission

Abstract

A method and system of ablating melanin are provided. Stepwise multi-photon fluorescence is induced in melanin within a region of tissue. The fluorescence is detected, and at least a portion of the melanin from which the fluorescence is detected is ablated. The system and method can use a continuous wave laser in the near infrared range for the inducement and ablation of melanin, providing high resolution at low cost.

Claims

1. A method of ablating melanin comprising:

inducing stepwise multi-photon fluorescence in melanin within a region of tissue;

detecting the fluorescence from the melanin in the region; and

ablating at least a portion of the melanin from which the fluorescence is detected.

2. The method of claim 1, wherein the step of inducing fluorescence in the melanin comprises transmitting a beam of laser light from a continuous wave laser source to the region of tissue to activate fluorescence from the melanin within the region.

3. The method of claim 2, wherein a wavelength of the laser light ranges from 600 nm to 2 μ

m.

4. The method of claim 2, wherein the beam of laser light is scanned across an image plane or across multiple image planes, wherein each of the multiple image planes is located at a different depth within the region of tissue.

6. The method of claim 1, wherein the fluorescence is induced by irradiating the melanin in an image plane with radiation at a first intensity;

and

the melanin is ablated by irradiating at least a portion of the melanin in the image plane with radiation at a second intensity greater than the first intensity.

7. The method of claim 1, wherein the step of detecting the stepwise multi-photon fluorescence includes generating a map of the detected fluorescence, the map comprising a series of image planes, each image plane comprising a pixel array in which pixels where fluorescence has been detected are identified.

8. The method of claim 1, further comprising monitoring fluorescence from the region after ablation to determine completion of ablation.

9. The method of claim 1, wherein the fluorescence is detected at a resolution of less than 10 μ

m in an image plane, and the melanin is ablated at a resolution of less than 10 μ

m in an image plane.

10. The method of claim 1, wherein the step of ablating the melanin comprises transmitting a beam of laser light from a continuous wave laser source to the region of tissue to ablate at least a portion of the melanin within the region.

11. The method of claim 10, wherein a wavelength of the laser light ranges from 600 nm to 2 μ

m.

16. The method of claim 1, wherein in the steps of inducing fluorescence and ablating the melanin, the region of tissue is human skin.

17. A method of treating a melanin-related disease or condition comprising:

performing the method of claim 1, wherein the region of tissue is present in a subject in need thereof.

18. The method of claim 17, wherein the melanin-related disease or condition is selected from the group consisting of melanocytic lesion, congenital or acquired hyperpigmentation or melanin deposition, and other skin discoloration from melanin deposition,

wherein the melanocytic lesion is selected from the group consisting of benign nevus and malignant melanoma,

wherein the congenital or acquired hyperpigmentation or melanin deposition is selected from the group consisting of melasma, hyperpigmentation from chronic nutritional deficiency, congenital pigment deposition, Addison'"'"'s disease, McCune-Albright syndrome, sun damage, solar lentigo, deposition sun damage, ephelides, freckle, café

au lait macule, nevus of Ota, nevus of Ito, post inflammatory hyperpigmentation, nevus apilus, seborrheic keratosis, blue nevus, Becker'"'"'s nevus, uneven skin tone, and vitiligo;

or

wherein the other skin discoloration from melanin deposition is selected from the group consisting of deposition associated with metals or mercury poisoning, and skin discoloration due to a side effect from drug usage.

22. A method of lightening skin pigmentation comprising:

performing the method of claim 1, wherein the region of tissue is present in skin of a subject in need thereof.

23. A method of hair removal comprising:

performing the method of claim 1, wherein the region of tissue is present in a hair shaft of a subject in need thereof.

5. (canceled)

12-15. -15. (canceled)

19-21. -21. (canceled)

24. A system for ablating melanin comprising:

an objective lens assembly disposed on an optical path to focus light on an image plane within a region of tissue including melanin;

a first light source disposed to transmit a first light beam on the optical path to the image plane within the region of tissue, the first light beam comprising a wavelength sufficient to induce step-wise multi-photon fluorescence of melanin in the image plane;

a detector disposed to receive a step-wise multi-photon fluorescence signal from the melanin in the image plane returning along at least a portion of the optical path; and

a second light source disposed to direct a second light beam on the optical path to the image plane within the region of tissue, the second light beam comprising a wavelength sufficient to ablate melanin in the image plane within the region of tissue.

25. The system of claim 24, wherein the first light source comprises a continuous wave laser source and the second light source comprises a continuous wave laser Source.

27. The system of claim 24, wherein the wavelength of the first light beam ranges from 600 nm to 2 μ

m, and the wavelength of the second light beam ranges from 600 nm to 2 μ

m.

29. The system of claim 24, wherein the first light source comprises a lower power than the second light source.

32. The system of claim 24, wherein the second light beam from the second light source is operable to ablate melanin at a resolution of less than 10 μ

m in the image plane.

36. The system of claim 24, wherein the detector comprises a photon detector, a photomultiplier tube, avalanche photodiodes, a spectrometer, a CCD image array detector, or a CMOS photodiode array detector.

38. The system of claim 24, further comprising a scanning system operative to scan the light beams from the first light source and the second light source across the image plane.

39. The system of claim 24, wherein the objective lens assembly is movable with respect to the image plane within the region of tissue, whereby fluorescence of the melanin in multiple image planes can be induced and at least a portion of the melanin in multiple image planes can be ablated.

43. The system of claim 24, wherein:

the objective lens assembly and the first light source are selected to provide a light intensity at a focal area sufficient to induce fluorescence of melanin in the image plane, and the objective lens assembly and the second light source are selected to provide a light intensity at a focal area sufficient to ablate melanin in the image plane, and

further comprising a controller in communication with the objective lens assembly, the first light source, the second light source and the detector, wherein the controller is operative to store detected fluorescence signals from the melanin in the image plane and to control the second light source to ablate melanin at locations in the tissue corresponding to the detected fluorescence signals.

44. The system of claim 24, wherein at least the objective lens assembly and a portion of the optical path from the first light source and the second light source are housed within a hand-held device.

26. (canceled)

28. (canceled)

30-31. -31. (canceled)

33-35. -35. (canceled)

37. (canceled)

40-42. -42. (canceled)