Laser dermablator and dermablation

• US 6,447,503 B1
• Filed: 11/01/2000
• Issued: 09/10/2002
• Est. Priority Date: 01/29/1998
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Felsenstein, Jerome Marvin, Wynne, James Jeffrey, Gomory, Stephen Henry
• Primary Examiner(s): Gibson, Roy D.
• Application Number:
  US09/606,351
• Time in Patent Office: 678 Days
• Field of Search: 606/2, 606/9-12, 606/14-17, 607/88-89
• US Class Current: 606/9
• CPC Class Codes: A61B 18/20 using laser
• CPC Class Codes: A61B 18/203 applying laser energy to the outside of the body
• CPC Class Codes: A61B 2017/00061 spectrum
• CPC Class Codes: A61B 2017/00756 Port wine stains
• CPC Class Codes: A61B 2018/00452 Skin
• CPC Class Codes: A61B 2018/00636 Sensing and controlling the application of energy
• CPC Class Codes: A61B 2018/00738 Depth, e.g. depth of ablation
• CPC Class Codes: A61B 2018/00904 Automatic detection of target tissue
• CPC Class Codes: A61B 2018/20357 by movable optical fibre end
• CPC Class Codes: A61B 2018/20359 by movable mirrors, e.g. galvanometric
• CPC Class Codes: A61B 2018/207 mixing two wavelengths
• CPC Class Codes: A61B 2090/0436 Shielding
• CPC Class Codes: A61B 2090/049 against light, e.g. laser
• CPC Class Codes: A61B 2090/373 using light, e.g. by using optical scanners
• CPC Class Codes: A61B 90/37 Surgical systems with images on a monitor during operation

Abstract

A laser system (called a UV Dermablator) and method that enables a clean, precise removal of skin while minimizing collateral damage to the skin underlying the treated region. The depth of ablation can be controlled via feedback from the physiology of the skin, namely the infusion of blood into the area of excision when skin has been ablated to a sufficient depth to produce bleeding. A second laser, such as a uv light source with a different wavelength, to penetrate the blood, heating it sufficiently to coagulate the blood. Other features provide precise control, permitting the epidermis to be removed down to the papillary dermis, following the undulations of the papillary dermis. This lateral and depth control may be accomplished by using careful observation, assisted by spectroscopic detection, to identify when the epidermis has been removed, exposing the underlying dermis, with spatial resolution appropriate for the spacing of the undulations of the papillary dermis. Yet other features which provide a feedback control mechanism which utilizes the optical characteristics such as the color, appearance and remittance of the definable skin layers to control the depth of ablation at each location.

Claims

1. A surgical system for removing skin, comprising:

an ArF laser capable of delivering a fluence F exceeding an ablation threshold fluence F_th,

a control mechanism operatively coupled to the ArF laser, for directing light from the ArF laser to locations on the skin and determining if a skin location has been ablated to a desired depth,

a coagulating light source having a different wavelength than the ArF laser and a relatively high blood absorption characteristic;

means for detecting the appearance of blood at a given skin location; and

means for switching to the coagulating light source, in response to the detection of blood at a given skin location.

2. The system of claim 1 further comprising:

the coagulating light source is a krypton fluoride (KrF) laser having a wavelength of approximately 248 nm.

3. The system of claim 1 further comprising:

the coagulating light source is a xenon chloride (Xecl) laser having a wavelength of approximately 308 nm.

4. The system of claimed further comprising:

the coagulating light source is a xenon fluoride (XeF) laser having a wavelength of approximately 351 nm.

5. A surgical system for removing skin comprising:

a pulsed light source capable of delivering a fluence F exceeding an ablation threshold fluence F_th; and

a control mechanism, operatively coupled to the light source, for directing light from the light source to locations on the skin and determining if a skin location has been ablated to a desired depth, the control mechanism further comprising;

one or more rotatable mirrors, the mirrors positioned in the light source path for controllably scanning the light from the light source;

one or more motors, coupled to the mirrors, for angularly rotating and feeding back angular positions of the one or more mirrors; and

a computer, coupled to the light source and the motors for controlling the motors and selectively shuttering the light source at a given location on the skin.

6. A surgical system for removing skin, comprising:

a pulsed light source capable of delivering a fluence F exceeding an ablation threshold fluence F_th;

a second light source illuminating the skin;

a control mechanism, coupled to the pulsed light source for directing light from the pulsed light source to locations on the skin and controllably ablating a skin location to a desired depth;

a feedback mechanism coupled to the control mechanism, the feedback mechanism comprising at least one photodetector having an input and an output the input receiving light from the second light source that is scattered/reflected/fluoresced by the skin, and the output providing a feedback signal to the control mechanism, which is adapted for detecting a change in the spectral shape or brightness of the light scattered/reflected/fluoresced by the skin and causing the pulsed light source to be inhibited at a given skin location, in response to the change; and

an active mask array, coupled to the feedback mechanism, for selectively shuttering the light source at a given location that has been ablated to the desired depth.

7. A surgical robot/laser system for removing skin, comprising:

a pulsed light source capable of delivering a fluence F exceeding an ablation threshold fluence F_th;

a control mechanism, operatively coupled to the pulsed light source, for directing light from the pulsed light source to locations on the skin and determining if a skin location has been ablated to a desired depth;

a camera for visualizing an image of the locations on the skin; and

a computer, coupled to the camera, the computer having an output for displaying and an input for designating the locations of the skin to which the laser is directed.

8. A The system of claim 7, further comprising:

a registration means for relating coordinates of a point in one patient coordinate frame of reference to a corresponding position in the robot/laser frame of reference.

9. The system of claim 8, said registration means further comprising:

means for attaching fiducials to the skin;

a movable tracking laser, coupled to the computer, for recording 3D coordinates of the fiducials; and

triangulation means, for establishing 3D locations of the fiducials in the tracking laser frame of reference.

10. The system of claim 9, the registration means further comprising:

means for relating points corresponding to an area of skin in the patient frame of reference subsequent to a change in position, to the same area of skin in a patient frame of reference prior to said change in position.

11. The system of claim 9, the registration means further comprising means for accurately directing the light source by relating points on an area of skin defined in a digital image, to an area of skin on the patient.

12. The system of claim 8, the registration means further comprising:

means for attaching fiducials to the skin;

a pair of cameras, coupled to the computer and mounted at fixed positions relative to the robot/laser system for recording coordinates of the fiducials;

calibration means for relating the fixed positions of the cameras to the robot/laser system from a predetermined calibration transformation; and

a camera model for mapping the relationship between each location in 2D camera images and a set of 3D points in an imaged space that map to it.

13. The robot/laser system of claim 7, further comprising:

one or more rotatable mirrors, the mirrors positioned in the light source path for controllably scanning the light source; and

one or more motors, coupled to the mirrors, for angularly rotating and feeding back angular positions of the one or more mirrors.

14. The system of claim 7, further comprising a flexible optical fiber bundle having an output end and an input end, the output end being attached to a mask for affixing to the patient and the input end adapted for receiving the light source in a predetermined manner.

15. The system of claim 14, further comprising:

a removable mirror located adjacent to the input end for viewing the skin through the fiber bundle using the camera.

16. The system of claim 7, wherein the robot/laser system further comprises:

a second light source illuminating the skin being ablated, wherein light from the second light source is scattered/reflected/fluoresced from the ablated location; and

a photodetector having an input and an output;

the input for receiving the light from the second light source; and

the output coupled to the system and providing a feedback signal to the system for inhibiting the pulsed light source at a given location.

17. A surgical system for removing skin, comprising:

a pulsed light source capable of delivering a fluence F exceeding an ablation threshold fluence F_th; and

a control mechanism, operatively coupled to the pulsed light source, for directing light from the pulsed light source to locations on the skin and determining if a skin location has been ablated to a desired depth, the control mechanism including an alignment mechanism, further comprising;

a visible laser, said laser emitting a beam illuminating the skin at a location coincident with the ablating light;

means for scanning the beam across the locations on the skin; and

means for recording scanned beam positions, coupled to said means for scanning, for subsequent automatic scan of an ablating light source across the locations on the skin.

18. In a surgical system including an ArF laser capable of delivering a fluence F exceeding an ablation threshold fluence F_th, a method for removing skin comprising the steps of:

directing light from the ArF laser to locations on the skin;

controllably determining if a skin location has been ablated to a desired depth;

providing a coagulating light source having a different wavelength than the ArF laser and a relatively high blood absorption characteristic;

detecting the appearance of blood at a given skin location; and

switching to the coagulating light source.

19. The method of claim 18 wherein the coagulating light source is selected from a group consisting of:

a krypton fluoride (KrF) laser having a wavelength of approximately 248 nm;

a xenon chloride (XECL) laser having a wavelength of approximately 308 nm; and

a xenon fluoride (XeF) laser having a wavelength of approximately 351 nm.

20. In a surgical system including a pulsed light source capable of delivering a fluence F exceeding an ablation threshold fluence F_th, a method for removing skin, comprising the steps of:

directing light from the pulsed light source to locations on the skin;

receiving, from a second light source, light that is scattered/reflected/fluoresced by the skin;

detecting a change in a spectral shape or brightness of the light scattered/reflected/fluoresced by the skin; and

controllably ablating a given skin location to a desired depth by inhibiting the pulsed light source at the given location. in response to the change, the inhibiting including the step of selectively shuttering the pulsed light source at a given skin location that has been ablated to the desired depth.

21. In a surgical system including a laser capable of delivering a fluence F exceeding an ablation threshold fluence F_th, a method for removing skin, comprising the steps of:

directing light from the laser to locations on the skin;

controllably determining if a skin location has been ablated to a desired depth;

visualizing an image of the locations on the skin; and

designating and displaying the locations of the skin to which the laser is directed.

22. The method of claim 21, wherein the system comprises a robot/laser system, further comprising the step of relating coordinates of a point in one patient coordinate frame of reference to a corresponding position in the robot/laser frame of reference.

23. The method of claim 22, further comprising the steps of:

attaching fiducials to the skin;

recording 3D coordinates of the fiducials; and

establishing 3D locations of the fiducials in the tracking laser frame of reference.

24. The method of claim 23, further comprising the steps of:

relating points corresponding to an area of skin in the patient frame of reference subsequent to a change in position, to the same area of skin in a patient frame of reference prior to said change in position.

25. The method of claim 23, further comprising the step of accurately directing the light source by relating points on an area of skin defined in a digital image, to an area of skin on the patient.

26. The method of claim 22, further comprising the steps of:

attaching fiducials to the skin;

providing a pair of cameras, mounted at fixed positions relative to the robot/laser system for recording coordinates of the fiducials;

relating the fixed positions of the cameras to the robot/laser system from a predetermined calibration transformation; and

mapping the relationship between each location in 2D camera images and a set of 3D points in the imaged space that map to it.

27. The method of claim 21, further comprising the steps of

affixing a flexible optical fiber bundle having an output end and an input end, the output end coupled to a mask for the skin and the input end adapted for receiving the light source.

28. The method of claim 21, wherein the robot/laser system further comprises:

illuminating the skin with a second light source, wherein light from the second light source is scattered/reflected/fluoresced from the ablated location;

receiving the light from the second light source; and

inhibiting the pulsed light source at a given location, in response to said receiving step.

29. In a surgical system including an ablating light source capable of delivering a fluence F exceeding an ablation threshold fluence F_th, a method for removing skin, comprising the steps of:

directing light from the ablating light source to locations on the skin;

controllably determining if a skin location has been ablated to a desired depth;

illuminating the skin with a beam from a visible laser at a location coincident with the ablating light;

scanning the beam across the locations on the skin;

recording scanned beam positions, in response to said scanning step; and

automatically scanning the ablating light source across the locations on the skin, in response to said recording step.