Method and an apparatus for controlled destruction of tissue

• US 6,629,973 B1
• Filed: 07/16/2001
• Issued: 10/07/2003
• Est. Priority Date: 01/25/1999
• Status: Expired due to Term

• Current Assignee: Elekta AB
• Original Assignee: Elekta AB
• Inventors: Nilsson, Gert, Wårdell, Karin, Eriksson, Ola
• Primary Examiner(s): Dvorak, Linda C. M.
• Assistant Examiner(s): Vrettakos, Peter J
• Application Number:
  US09/889,449
• Time in Patent Office: 813 Days
• Field of Search: 606/1-3, 606/10, 606/13-16, 606/32, 606/34, 606/41, 606/40, 600/300, 600/309, 600/310, 600/342, 607/88-89
• US Class Current: 606/40
• CPC Class Codes: A61B 18/148 having a short, rigid shaft for accessing the inner body transcutaneously, e.g. for neurosurgery or arthroscopy
• CPC Class Codes: A61B 2018/00434 Neural system
• CPC Class Codes: A61B 2018/00577 Ablation
• CPC Class Codes: A61B 2018/00642 with feedback, i.e. closed loop control
• CPC Class Codes: A61B 2018/00761 Duration
• CPC Class Codes: A61B 2018/00791 Temperature

Abstract

The present invention relates to an apparatus for destroying a predetermined defined volume (10) in a tissue, such as generating controlled coagulation, so-called lesion, in the brain. More particularly, the apparatus comprises a main unit (1) for transmitting a tissue-destroying medium comprising a control unit (3) for controlling the medium transmission, and a transferring means (4), such as an electrode, which is connected to said main unit and adapted to be inserted into the predetermined volume for transferring the transmitted medium to the volume. The apparatus according to the invention is characterised in that it further comprises a measuring means (5-8) for measuring at least one optical characteristic of the predetermined volume, the optical characteristic varying with the size of the destroyed volume, the measuring means being connected to said control unit for controlling the supply of the tissue-destroying medium on the basis of the measured optical characteristic.

Claims

1. An apparatus for destroying a predetermined defined volume in a tissue, the apparatus comprising:

a main unit for transmitting a tissue-destroying medium , the main unit comprising a control unit for controlling the medium transmission, and a transferring apparatus connected to the main unit and adapted to be inserted into the predetermined volume for transferring the transmitted medium to the predetermined volume;

measuring apparatus for measuring at least one optical characteristic of the predetermined volume, the at least one measured optical characteristic varying with a size of a destroyed volume of tissue, the measuring apparatus being connected to the control unit for controlling a supply of the tissue-destroying medium based on the at least one measured optical characteristic, the at least one optical characteristic including Doppler frequency, the measuring apparatus being adapted to calculate a concentration of movable blood cells in the predetermined volume based on the Doppler frequency and, based on the Doppler frequency, estimate the size of the destroyed volume.

2. An apparatus as claimed in claim 1, wherein the measuring apparatus is adapted to continuously measure the at least one optical characteristic of the predetermined volume during transmission of the medium.

3. An apparatus as claimed in claim 1, wherein the control unit is adapted to transmit medium adapted to cause controlled coagulation of the predetermined volume of tissue.

4. An apparatus as claimed in claim 3, wherein the control unit is adapted to transmit medium including high-frequency current.

5. An apparatus as claimed in claim 1, wherein the measuring apparatus comprises a measuring unit and a measuring probe connected thereto, the measuring probe including at least one waveguide for delivering light generated by a source of light to the predetermined volume and at least one return guide for returning reflected light to the measuring unit, the measuring unit being adapted to detect the at least one optical characteristic in the reflected light.

6. An apparatus as claimed in claim 5, wherein the source of light is a laser.

7. An apparatus as claimed in claim 5, wherein the measuring probe is connected to the transferring apparatus.

8. An apparatus as claimed in claim 1, wherein movable blood cells within the measured volume (CMBC) are substantially estimated according to:

$\mathrm{CMBC}=k<br><br>\left(\ln <br><br>\left(1-\frac{1}{{\mathrm{\eta <br><br>}}^2<br><br>i_T}<br><br>\text{\hspace{1em}<br><br>}<br><br>{\int <br><br>}_{{\mathrm{\omega <br><br>}}_1}^{{\mathrm{\omega <br><br>}}_2}<br><br>P<br><br>\left(\mathrm{\omega <br><br>}\right)<br><br>\text{\hspace{1em}<br><br>}<br><br><br><br>\mathrm{\omega <br><br>}\right)\right)$

wherein P(ω

) is the spectral density of the Doppler signal, ω

the low-frequency threshold, ω

₂ the high-frequency threshold, k is a constant, η

² is an instrumental factor mainly depending on an optical coherence of a signal in the measuring unit and i_T is a total photo current.

9. An apparatus as claimed in claim 1, wherein the apparatus is adapted to distinguish phase transitions of the predetermined volume based on the Doppler frequency during the transmission of the tissue-destroying medium.

10. An apparatus as claimed in claim 5, wherein the source of light is a laser and has a wavelength in the range of 600-900 nm.

11. An apparatus as claimed in claim 5, wherein the measuring probe is connected to the transferring apparatus and is integrated therewith.