Coaxial dual laser

• US 5,865,828 A
• Filed: 08/08/1997
• Issued: 02/02/1999
• Est. Priority Date: 08/08/1997
• Status: Expired due to Fees

• Current Assignee: James C. Jeng
• Original Assignee: James C. Jeng
• Inventors: Jeng, James C.
• Primary Examiner(s): Cohen, Lee
• Assistant Examiner(s): YARNELL, BRYAN KEITH
• Application Number:
  US08/907,622
• Time in Patent Office: 543 Days
• Field of Search: 606/2, 606/3, 606/9-11, 606/13, 606/17, 606/18
• US Class Current: 606/2
• 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 2018/00577 Ablation
• CPC Class Codes: A61B 2018/00595 Cauterization
• CPC Class Codes: A61B 2018/00642 with feedback, i.e. closed loop control
• CPC Class Codes: A61B 2018/00904 Automatic detection of target tissue
• CPC Class Codes: A61B 5/0071 by measuring fluorescence emission
• CPC Class Codes: A61B 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light

Abstract

A process and apparatus for ablating surface lesions is disclosed. The process is unique because of the ability to precisely excise complex topographies without blood loss, gated by the degree of surface small vessel blood flow via detection of Doppler shift. The most fitting application is the immediate, bloodless, and precise excision of thermal burn wounds, hitherto impossible and extremely desirable. A variation of the invention is disclosed which incorporates gating both by surface small vessel blood flow and fluorescence tagging. This embodiment has particular application in ablating neoplasms.

Claims

1. A method for ablating tissue, comprising:

providing a first laser channel,

providing a second laser channel, the first laser channel and the second laser channel being coaxial,

controlling the first laser channel to detect blood flow in a target via Doppler shift analysis,

identifying at least one of desired tissue and undesired tissue in the target in accordance with the blood flow detected via Doppler shift analysis,

controlling the second laser channel in response to the Doppler shift analysis to ablate the undesired tissue,

whereby topographically complex tissue is precisely excised from the target with minimal blood loss, leaving a sterile surface free of undesired tissue.

2. The method of claim 1, comprising:

tagging monoclonal antibodies in the target with at least one of a fluoresceine or rhodamine dye,

providing a third laser channel for exciting the dye tagged monoclonal antibodies,

controlling the third laser channel to detect fluorescence from the dye tagged monoclonal antibodies,

controlling the second laser channel in response to the Doppler shift analysis

and to the detected fluorescence from the dye tagged monoclonal antibodies to ablate the undesired tissue.

3. The method of claim 1, wherein the undesired tissue comprises hyper-vascular tissue.

4. The method of claim 1, wherein the undesired tissue defines a depth, wherein the second laser channel originates from a laser source, wherein the laser source has a pulse duration and a wattage, and comprising the step of:

modifying at least one of the pulse duration and the wattage of the laser source to thereby modify the depth of undesired tissue ablated by the second laser channel.

5. The method of claim 1, wherein the first laser channel and the second laser channel define an optical axis, and comprising:

moving the optical axis from a first location in the target to a second location in the target after the step of controlling the second laser channel to ablate undesired tissue,

repeating, at the second location, the steps of controlling the first laser channel to detect blood flow via Doppler shift analysis, identifying at least one of desired tissue and undesired tissue, and controlling the second laser channel in response to the Doppler shift analysis to ablate the undesired tissue.

6. The method of claim 1, wherein the target defines a plurality of locations and wherein, at each of the plurality of locations, the steps of controlling the first laser channel to detect blood flow via Doppler shift analysis, identifying at least one of desired tissue and undesired tissue, and controlling the second laser channel in response to the Doppler shift analysis to ablate undesired tissue are repeated until desired tissue is detected.

7. The method of claim 5 or 6, comprising:

selecting a blood flow threshold value which distinguishes undesired tissue and desired tissue, wherein the step of selecting a blood flow threshold value is performed after each ablation of undesired tissue.

8. The method of claim 1, comprising:

generating an image of the target in which areas of desired tissue and undesired tissue are visually distinguishable.

9. The method of claim 1, comprising:

selecting a blood flow threshold value which distinguishes undesired tissue and desired tissue.

10. The method of claim 1, wherein the second laser channel originates from a laser source defines a channel width, wherein the laser source has a laser power, a dwell time adjustment, and a scanning raster adjustment, and wherein the step of controlling the second laser channel comprises at least one of controlling the channel width, the laser power, the dwell time adjustment, and the scanning raster adjustment.

11. A device for ablating tissue, comprising:

a first laser channel,

a second laser channel, the first laser channel and the second laser channel being coaxial,

means for controlling the first laser channel to detect blood flow in a target via Doppler shift analysis,

means for identifying at least one of desired tissue and undesired tissue in the target in accordance with the blood flow detected via Doppler shift analysis,

means for controlling the second laser channel in response to the Doppler shift analysis to ablate the undesired tissue,

whereby topographically complex tissue is precisely excised from the target with minimal blood loss, leaving a sterile surface free of undesired tissue.

12. The device of claim 11, wherein monoclonal antibodies in the target are tagged with at least one of a fluoresceine or rhodamine dye, comprising:

a third laser channel for exciting the dye tagged monoclonal antibodies,

means for controlling the third laser channel to detect fluorescence from the dye tagged monoclonal antibodies, and

means for controlling the second laser channel in response to the Doppler shift analysis and to the detected fluorescence from the dye tagged monoclonal antibodies to ablate the undesired tissue.

13. The device of claim 11, wherein the undesired tissue comprises hyper-vascular tissue.

14. The device of claim 11, wherein the undesired tissue defines a depth, wherein the second laser channel originates from a laser source, wherein the laser source has a pulse duration and a wattage, and comprising:

means for modifying at least one of the pulse duration and the wattage of the laser source to thereby modify the depth of undesired tissue ablated by the second laser channel.

15. The device of claim 11, wherein the first laser channel and the second laser channel define an optical axis, and comprising:

means for moving the optical axis from a first location in the target to a second location in the target after the step of controlling the second laser channel to ablate undesired tissue,

means for repeating, at the second location, the steps of controlling the first laser channel to detect blood flow via Doppler shift analysis, identifying at least one of desired tissue and undesired tissue, and controlling the second laser channel in response to the Doppler shift analysis to ablate the undesired tissue.

16. The device of claim 11, wherein the target defines a plurality of locations and comprising means for repeating, at each of the plurality of locations, the means for controlling the first laser channel to detect blood flow via Doppler shift analysis, identifying at least one of desired tissue and undesired tissue, and controlling the second laser channel in response to the Doppler shift analysis to ablate undesired tissue until desired tissue is detected.

17. The device of claim 15 or 16, comprising:

means for selecting a blood flow threshold value which distinguishes undesired tissue and desired tissue, wherein the means for selecting a blood flow threshold value is performed after each ablation of undesired tissue.

18. The device of claim 11, comprising:

means for generating an image of the target in which areas of desired tissue and undesired tissue are visually distinguishable.

19. The device of claim 11, comprising:

means for selecting a blood flow threshold value which distinguishes undesired tissue and desired tissue.

20. The device of claim 11, wherein the second laser channel originates from a laser source defines a channel width, wherein the laser source has a laser power, a dwell time adjustment, and a scanning raster adjustment, and wherein the means for controlling the second laser channel comprises at least one of controlling the channel width, the laser power, the dwell time adjustment, and the scanning raster adjustment.