US20010020165A1

US20010020165A1 - Laser applicator set

Info

Publication number: US20010020165A1
Application number: US09/155,958
Authority: US
Inventors: Thomas Vogl; Martin Mack; Frank Kniep
Original assignee: Somatex Medizintechnische Instrumente GmbH
Current assignee: Somatex Medizintechnische Instrumente GmbH
Priority date: 1996-04-04
Filing date: 1997-04-04
Publication date: 2001-09-06
Anticipated expiration: 2017-04-04
Also published as: PL329173A1; CA2251370A1; JPH11508173A; ES2157580T3; CZ313798A3; EP0891157A1; DE19702898A1; EP0891157B1; PT891157E; CZ288864B6; CA2251370C; NO984566D0; NO984566L; WO1997037601A1; ATE199637T1; DE59703143D1; US6283958B1; DK0891157T3

Abstract

The invention discloses a laser application set, which is an interventional application set for minimum invasive, laser-induced thermotherapy of soft-tissue tumors.

In accordance with the invention the laser application set is designed in such a manner that an introductor tube (6) with a stylet (12) is provided and accommodates a tunneled catheter (17) with an internal stylet (20).

Description

The present invention discloses a laser application set, which is an interventional application set for minimum invasive laser-induced thermotherapy of soft-tissue tumors.

It is known as state of the art that laser radiation which emerges from an optical waveguide, e.g. the irradiation of an Nd:YAG laser at 1064 nm, employing a silica glass optical fiber (of the PCS, HCS or ALL SILICA type) as beam guidance system, may be used to cause radial-symmetric coagulation necroses in biological tissue. In order to do so, the light-conducting fiber is either placed upon the tissue or inserted into the tissue. However, the disadvantage of this method of therapy is that there occurs a high power density at the place of contact between fiber end area and tissue which, already above some 100 mW luminous power and depending on the fiber diameter, results in a carbonization of the tissue surface and thus, due to the high level of carbon absorption, prevents the further diffusion of radiation within the tissue.

Further an application device for laser radiation (DE4137983A1) is known, in which the beam-conducting end of the optical waveguide that faces the object to be treated is arranged in a tubular enveloping body whose front face is transparently shut to laser radiation, in particular in a plastic hose whose front end facing said object is air- and fluid-tight sealed, with the front face of the enveloping body and/or the end of the optical waveguide being equipped with a spreading device for laser radiation that has a spreading volume. There, also multiple chambered hoses are employed in order to provide possibly required cooling via a connected distributor piece.

Also known is a U.S. Pat. No. 5,312,392 “A method of treating benign tumors”. In which a trocar, that contains an optical waveguide, is inserted into the tumor to be treated. The position of the trocar with the optical waveguide is monitored using ultrasound. The disadvantage of this method is that any repositioning of the trocar with the optical waveguide is only possible with a new puncture.

The disadvantage of all previously applied methods of therapy is that they fail to allow for a repositioning of the relevant enveloping body which contains the laser and, hence, any faulty positioning of the laser or the enveloping body, respectively, requires a new puncture. A further disadvantage is that with a defective laser wire (optical waveguide) yet another intervention into the soft-tissue tumor to be treated becomes necessary.

The object of the invention is the implementation of a laser application set which ensures a gentle treatment of a patient and facilitates monitoring by means of a computer tomograph or a magnetic resonance tomograph, respectively.

The aim of the invention is the creation of a laser application set which neutralizes the disadvantages of the prior art and the previous methods of therapy by providing an interventional application set for laser therapy which enables a repositioning and requires only a single puncture of the tumor to be treated.

The aim according to the invention is attained by implementing a laser application set in accordance with Nos. 1 to 9 of the patent claims.

The laser application set consists of an introducer tube with an internal stylet. The internal stylet is locked with the introducer tube by means of a thread. The internal stylet is designed in such a manner that it projects by approx. 1 cm over and beyond the end of the introducer tube and has a pointed form. The stylet is of a hollow construction. A grip end at the external end of the stylet may be used to undo its locking by turning, after which the stylet may be removed from the introducer tube. The proximal end of the introducer tube is provided with a T piece. A silicone lamella is placed between the T piece and the introducer tube proper in order to provide a high elasticity during the insertion into the respective tumor. The silicone lamella is designed as a silicone membrane in the form of a forward-folding buckling lamella. A hose lead with a downstream three-way faucet is connected to the T piece. The hose lead and the connected three-way faucet may be used to apply cooling agents, lubricants and/or other additional local anesthetics. This opportunity of supply essentially contributes to providing a largely painless therapy also for capsular lesions. In addition, the hose lead allows for blood control of the patient under treatment during the therapy session. An external thread to lock the stylet is located opposite the silicone lamella of the T piece. Moreover, the T piece is equipped with a membrane which prevents any fluids from leaking during the therapy session.

A further preferred embodiment is the provision of the introducer tube with marks which facilitate the exact positioning of the application set. The individual marks are appended at a distance of 1 cm from each other.

A further component of the laser application set is a tunneled catheter with an internal stylet. The tunneled catheter with the internal stylet is inserted upon the removal of the stylet from the introducer tube. The tunneled catheter is designed in such a manner that its distal end is air- and fluid-tight sealed and has a tunneled catheter tip which significantly contributes to the possibility that a repositioning may be made of the tunneled catheter in the tumor to be treated. The tunneled catheter is also provided with marks at a distance of 1 cm from each other which allow for an exact positioning of the tunneled catheter when inserted into the introducer tube. The beginning of the marking on the tunneled catheter is designed in such a manner that, upon reaching the first mark, the catheter projects approx. 30 mm from out of the introducer tube, which is important for the operability of the laser application set. Within the tunneled catheter there is an internal stylet whose end is equipped with a grip end for its removal. The internal stylet is made from stainless steel, which preferentially consists of a paramagnetic material. This stainless steel wire is wrapped with a synthetic sheathing. The essential fact is that the internal stylet provides stabilization to the insertion of the tunneled catheter into the introducer tube and, hence, enables the exact positioning of the tunneled catheter tip into the tumor to be treated. A further essential feature of the invention is that the introducer tube with the stylet as well as the tunneled catheter with its internal stylet are made from materials which may be used for the monitoring of the method of therapy by means of computer tomography (CT) or magnetic resonance tomography (MRT), respectively. The materials of the introducer tube and the stylet as well as the tunneled catheter are preferably from synthetic materials, with PE, PTFE, FEP plastics being employed.

The laser application set according to the intervention has the following advantages over the known application sets for laser therapies of soft-tissue tumors.

The marks appended to the introducer tube allow for an exact positioning of the introducer tube on the patient. The exact position relation of the laser application set to the lesion is of decisive significance for a successful therapy. Further, it can be established that the membrane located in the T piece of the introducer tube facilitates a safe and non-slipping positioning of the tunneled catheter according to the invention. The tunneled catheter is thermoresistant up to a max. 400° C. and its distal end is air- and fluid-tight sealed. The tunneled catheter, which thus prevents a direct contact between the laser applicator and the patient, is equipped with an internal stylet, consisting of a wire from paramagnetic material, that essentially contributes to the stabilization of the tunneled catheter during its insertion. Thus, on the one hand the tunneled catheter may be kept thin while, on the other, the required stabilization is still achieved. The marks appended to the introducer tube allow for an exact positioning of the introducer tube and prevent a fusion of the introducer tube when the light transmitting tunneled catheter fails to project sufficiently from the introducer tube system that is impervious to laser light. A repositioning of the tunneled catheter, which is inserted internally into the introducer tube, is permitted as a result of permanent monitoring by computer tomograph or a magnetic resonance tomograph, respectively. In case that a defect or other malfunction is found during the insertion of the laser applicator a new laser applicator may be inserted at any time without having to commence a new therapy phase. The appropriate composition of materials has created a laser application set which is compatible with monitoring by CT, MRT or nuclear magnetic resonance tomography (NMRT), respectively.

A further advantage according to the invention lies in that upon the completion of the laser therapy and removal of the introducer tube therapeutic agents, such as tissue glue, may be introduced via the hose lead and the pertaining three-way faucet, and thus a dispersion of the cells of the treated tumor is inhibited which previously had been a serious disadvantage in the laser therapy of tumors.

Furthermore, the laser application set according to the invention facilitates the single-time puncture of the tumor to be treated, thus preventing any dispersion of the tumor.

The following aspects should be considered as further application indications of the laser application set according to the invention. The laser application set according to the invention enables a percutaneous laser therapy of, e.g., hepatic metastases which cannot be surgically removed due to their distribution. Also operable metastases may be subjected to laser therapy when a patient refuses surgery. In addition, a patient may be brought into an operable condition by employing the laser application set to treat one or more metastases by laser treatment. The set allows for the treatment of metastases of a max. diameter of 4 cm. Further fields of application of the laser application set worth mentioning are the palliative therapy of benign tumors in the head/neck region and the percutaneous therapy of soft-tissue tumors in the pelvic region.

The tunneled catheter is designed with a connection piece. The locking piece of an inner tunneled catheter is appended to the connection piece, with the inner tunneled catheter being located within the tunneled catheter of the laser application set. A flushing and/or cooling agent outlet is provided at the distal end of the inner tunneled catheter The connection piece of the tunneled catheter and the locking piece of the inner tunneled catheter may be firmly interlocked by means of a sealing thread at the connection piece. The connection piece and the locking piece are each equipped with connectors to which T pieces are attached. The T pieces may be used to connect a pump for the recirculation of the flushing and/or cooling agent. Thus, a flushing and/or cooling fluid, preferably sterile isotonic sodium chloride solution, is led via a T piece of the inner tunneled catheter and on via the connector of the locking piece into the inner tunneled catheter, with the backflow occurring between the inner tunneled catheter and tunneled catheter via the connection piece and the connector to the T piece. Thus optimum cooling is provided to the entire area of the punctured external tissue.

The locking piece of the inner tunneled catheter is equipped with a membrane sealing. The internal stylet of the laser application set is inserted and removed, respectively, and also the laser applicator is inserted during a therapy session through this membrane sealing. A further membrane sealing at the connection piece serves as a sealing when the inner tunneled catheter is inserted into the tunneled catheter.

The particular design of the tunneled catheter provides further essential advantages for the use of the laser application set. The employment of the laser application set ensures optimum conditions to achieve coagulation necroses with a max. diameter of 20 mm to 25 mm. It is due to the heat dissipation, that is essentially conditioned by blood flow in the vessels and diffusion in the tissue, that it is usually impossible in vivo to induce coagulation necroses larger than 2*2*2 cm by using the laser application set without inserting the inner tunneled catheter. However, the majority of soft-tissue tumors have a size of 3 cm to 4 cm when a diagnosis is made. In order to coagulate a volume of 4*4*4 cm, with the previous use of the laser application set of the main patent, eight laser applications and, hence, eight punctures are necessary. The laser power is approx. 5 watts applied over a 20-minute therapy session. What is essential is that the tunneled catheter configuration allows the laser application set to achieve coagulation necroses larger of up to a max. 4.2*4.2*4.2 cm with one laser application, during which laser power of up to 30 watts is applied up to 15 minutes. The tunneled catheter, which is used as part of the laser application set, achieves that high laser powers can only be applied when a cooling of the tissue immediately adjacent to the tunneled catheter is ensured and thus any carbonization or vaporization of tissue is prevented. Carbonization or vaporization of the tissue immediately adjacent to the tunneled catheter prevents a further propagation of the coagulation zone since the entire laser power at the employed wavelength of 1064 nm would be absorbed in the immediate vicinity of the tunneled catheter. In particular the laser application catheter in conjunction with the tunneled catheter of the laser application set in the main application yields the below advantages for the patient:

1. In order to coagulate a lesion measured to be 4*4*4 cm the use of a tunneled catheter in conjunction with the laser application set requires only one laser application in the place of eight laser applications with the laser application set.

2. Furthermore, the clear decrease of the number of punctures reduces the risk of puncture complications, such as hemorrhage, vascular and nerve injuries as well as organ injuries.

3. Since the number of punctures required for tumor treatment decreases also the risk of tumor dispersion and thus the risk of vaccination metastasis is reduced.

4. Furthermore, the use of the special tunneled catheter in conjunction with the laser application set results in a clear cost saving potential of this method because with a lesion measured to be 4*4*4 cm no longer eight puncture tracks have to be sealed wit fibrin glue but only one puncture track.

5. Normally, a patient does not tolerate eight punctures in one therapy session, hence, the second half of the tumor often had to be subject to laser therapy in a second therapy session. This second therapy session may fall away when the tunneled catheter of the laser application set is used.

6. In case of lesions up to a diameter of 4 cm the use of the tunneled catheter with the laser application set attains a clearly higher probability of a 100% tumor coagulation. Thus, this application is able to achieve a clear reduction of the local recurrence rate.

The advantageous further developments of the invention are, respectively, characterized in the dependent claims or are represented below in greater detail together with a description of the preferred practical example of the invention by means of figures. The figures illustrate the following: [0026]
FIG. 1 Puncture needle [0027]
FIG. 2 Stainless steel wire; [0028]
FIG. 3 Stylet introducer tube; [0029]
FIG. 4 Introducer tube with T piece; [0030]
FIG. 5 Tunneled catheter; [0031]
FIG. 6 Internal stylet-tunneled catheter; [0032]
FIG. 7 Tunneled catheter with cooler; [0033]
FIG. 8 Tip of the tunneled catheter with cooler. [0034]
FIGS. [0035] 1 illustrates a puncture needle 1 with a contained needle stylet 2, which has a needle stylet tip 3. The puncture needle is of a known design. What is essential is that the puncture needle 1 consists of a paramagnetic material and thus may be applied in the MRT process. The puncture needle 1 has a length of approx. 200 mm and a diameter of approx. 1.3 mm. The needle stylet has a three-edged puncture tip which extends beyond the puncture needle 1. A grip end enables the smooth removal of the needle stylet 2 from the puncture needle 1.
FIGS. [0036] 2 illustrates a wire 4, which consists of stainless steel, with a special type of this wire 4 with a tongue end 5 being available, which is executed with a taper-ground tongue. In the depicted practical example the length of the wire is approx. 1 meter, with the tongue end 5 being approx. 100 mm long. The wire 4 is made from a paramagnetic material.
FIGS. 3 and 4 illustrate the introducer tube [0037] 6 and the stylet 12. The introducer tube 6 and the stylet 12 are made from synthetic materials, such as PE, PTFE, FEP. The length of the introducer tube 6 is approx. 100-200 mm and its diameter is approx. 1.5 mm up to 4 mm—depending on the practical example. The stylet 12 that is contained in the introducer tube 6 is executed with close tolerances—depending on the size of the introducer tube 6. The proximal end of the introducer tube 6 is equipped with a silicone lamella 10 to which a T piece 9 is connected. This silicone lamella 10 is designed as a silicone membrane in the form of a forward-folding buckling lamella. The silicone lamella 10 essentially improves handling of the introducer tube 6. The T piece 9 is equipped with a hose lead 8 and an adjacent three-way faucet 7. Via the three-way faucet 7 and the hose lead 8 to the T piece 9 it is possible to apply additional local anesthetics, such as lubricant, tissue glue, alcohol, etc., which essentially contributes to providing a largely painless therapy also for capsular lesions. Furthermore the T piece 9 is equipped with an external thread 13 to lock the stylet 12 with contained internal thread into the grip end 14. A membrane 16 is provided between the T piece 9 and the adjacent external thread 13 which prevents any fluids from leaking and facilitates a safe and non-slipping positioning of the tunneled catheter 17. The introducer tube 6 is provided with marks 11. These are preferably arranged at a distance of 1 cm from each other along the entire length of the introducer tube 6. Thus an exact positioning of the introducer tube 6 is ensured. In its locked state with the introducer tube 6 the stylet 12 has a length which is distinguished in that approx. 1 cm of the stylet tip 15 extend from the distal end of the introducer tube 6.
A further preferred design is that the [0038] stylet 12 is executed hollow. This hollow design form of the stylet 12 provides an increased lubricity during the insertion of the introducer tube 6 with the stylet 12 via the wire 4 into the patient.
FIGS. 5 and 6 illustrate the tunneled [0039] catheters 17 according to the invention with internal stylet 20. The tunneled catheter 17 made from a thermostable synthetic material which resists a max. temperature of 400° C. The preferred materials employed are PTFE and FEP. The tunneled catheter 17 has a length of approx. 400 mm. Essential of the invention is here the existing tip at the distal end of the tunneled catheter which is air- and fluid-tight sealed. The external diameter of the tunneled catheter may be between 1.5 mm and 4 mm, depending on the application form. This tunneled catheter 17 is equipped with an internal stylet 20 with a grip end 19. The internal stylet 20 is a wire which is made from a paramagnetic material and provided with a plastics coating. It is through this internal stylet 20 that the tunneled catheter 17, due to the high stability of the stainless steel wire, may be inserted with safe positioning into the internal stylet 20, and there are further control opportunities for the positioning of the tunneled catheter 17. The upper part of the tunneled catheter 17 is provided opposite the tunneled catheter tip 21 with marks which are arranged at a distance of 1 cm from each other. The first mark towards the tunneled catheter tip 21 is arranged in such a manner that approx. 30 mm of the tunneled catheter 17 project at the distal end of the introducer tube 6 upon insertion into the introducer tube 6 and reaching of the first mark. After removing the internal stylet 20 by the grip end 19 an optical waveguide for laser treatment of the respective tumor may be smoothly inserted. The positioning of the tunneled catheter 17 towards the introducer tube 6 by means of the marks on the tunneled catheter 17 according to the invention largely prevents that a fusion of the light source with the light impervious introducer tube 6 occurs during treatment with the optical waveguide since the tunneled catheter 17 always projects approx. 30 mm from the distal end of the introducer tube 6.
FIG. 7 illustrates a special embodiment of the tunneled catheter with cooling which is made up as follows. The tunneled [0040] catheter 17 of the laser application set is employed in the same manner, with the proximal end of the tunneled catheter 17 being equipped with a connection piece 22. A T piece 26 is connected to the connection piece 22 via a connector 25. A pump to convey flushing and/or cooling agent is attached to the T piece 26. A sealing thread at the connection piece 22 firmly interlocks a locking piece 23 of the inner tunneled catheter 30. The inner tunneled catheter 30 is located inside the tunneled catheter 17. The inner tunneled catheter 30 is designed in such a manner that it ends at the distal end 5 mm before the tunneled catheter tip 21. The inner tunneled catheter 30 is open at the distal end. A connection of a pump for a flushing and/or cooling agent is provided via a connector 24 and a T piece 27 above the locking piece 23 of the inner tunneled catheter 30. The cooling agent 31 flows via the T piece 24, connector 25, locking piece 23 and through the inner tunneled catheter 30 into the tip of the of the inner tunneled catheter 30 and on its flow back the flushing and/or cooling agent 31 is led between the tunneled catheter 17 and the inner tunneled catheter 30 via the connection piece 22, connector 25 and T piece 26 to the pump. Preferably a sterile isotonic sodium chloride solution is used as flushing and/or cooling agent. The laser applicator 33 is inserted into the inner tunneled catheter 30, thus ensuring maximum cooling of the entire punctured tissue, since the backflow between the tunneled catheter 17 and the inner tunneled catheter 30 transmits cooling to the entire area of the punctured tissue—which consists an advantage that is essential of the invention. In order to seal off the of the laser applicator 33 or the removal of the internal stylet 20 of the laser application set, respectively, a membrane sealing 28 is arranged in the locking piece 23 of the inner tunneled catheter 30. In order to seal off the insertion of the inner tunneled catheter 30 a further membrane sealing 29 is provided in the connection piece 22.
FIG. 8 illustrates the tip of the tunneled [0041] catheter 17 in its embodiment. It can be seen that the cooling agent 31 exits in the interior of the inner tunneled catheter 30 and at the outside of the tunneled catheter point 21 between the inner tunneled catheter 30 and the tunneled catheter 17. The laser applicator 33 projects beyond the distal end of the inner tunneled catheter 30, hence, the flushing and/or cooling agent cools the entire external tissue of the tumor to be treated.
The application according to the invention of the laser application set in a therapy of soft-tissue tumors is described as follows: [0042]
The tumor to be treated is punctured with the puncture needle [0043] 1 and the contained needle stylet 2 with its needle stylet tip 3. The three-edged needle stylet tip 3 makes for a good puncture efficiency of the puncture needle 1. Following the completion of a positive puncture the needle stylet 2 is removed from the puncture needle 1. Subsequently, a wire 4 is inserted up to the distal end of the puncture needle 1. The puncture needle 1 is removed via this wire 4. Then the introducer tube 6 with the locked stylet 12 is strung to the wire 4 and led into the tumor to be treated up to the distal end of the wire 4. The wire 4 is removed after the exact positioning of the introducer tube 6 with the stylet 12. As required, the necessary additional local anesthetics are supplied to the three-way faucet 7. A slight turn of the grip end 14 of the stylet 12 undoes the locking with the T piece 9 of the introducer tube 6 and the stylet 12 may be removed from the introducer tube 6.
A further preferred design is that marks are appended to the introducer tube [0044] 6 which permit an exact positioning of the introducer tube 6 into the tumor to be treated. Subsequently, the tunneled catheter 17 with contained internal stylet 20 is inserted into the introducer tube 6. While doing so, the marks on the tunneled catheter 17 permit an exact positioning of the introducer tube 6 into the tumor to be treated, with, as is essential of the invention, the first mark being designed in such a way that the tunneled catheter 17 projects by 30 mm from the distal end of the introducer tube 6. The internal stylet 20 is provided to improve correctability and stabilization during the insertion of the tunneled catheter 17. Following the removal of the internal stylet 20 by means of the grip end 19 an optical waveguide to perform the laser therapy is inserted until the distal end of the tunneled catheter 17. The permanent monitoring by means of CT or MRT processes, respectively, permits a respective exact positioning of the tunneled catheter 17 with the tunneled catheter point 21 according to the invention. Furthermore, the functioning of the inserted optical waveguide can be checked in order to prevent a fusion of the light source with the light impervious sheath of the introducer tube 6. The exact positioning with the help of the introducer tube 6 and the tunneled catheter 17 also enables the removal of defective optical waveguides and to replace such by a new optical waveguide and thus avoid a new puncture. Following the completion of the treatment via optical waveguide the latter is removed and subsequently also the tunneled catheter 17 and the introducer tube 6. While doing so it possible to introduce, e.g., tissue glue via the three-way faucet 7 and the hose lead 8 to the T piece 9 during the removal of the introducer tube 6 and thus an advantage according to the invention is provided by ensuring a minimum cell dispersion of the treated tumor while removing the introducer tube 6 which previously has been an essential disadvantage of the laser therapy of tumors.

REFERENCE SIGNS

[0045] 1. Puncture needle
[0046] 2. Needle stylet
[0047] 3. Needle stylet tip
[0048] 4. Wire
[0049] 5. Tongue-shaped end
[0050] 6. Introductor tube
[0051] 7. Three-way faucet
[0052] 8. Hose lead
[0053] 9. T piece
[0054] 10. Silicone lamella
[0055] 11. Mark
[0056] 12. Stylet
[0057] 13. External thread
[0058] 14. Grip end
[0059] 15. Stylet tip
[0060] 16. Membrane
[0061] 17. Tunneled catheter
[0062] 18. Mark
[0063] 19. Grip end
[0064] 20. Internal stylet
[0065] 21. Tunneled catheter tip
[0066] 22. Connection piece
[0067] 23. Locking piece
[0068] 24. Connection
[0069] 25. Connection
[0070] 26. T piece
[0071] 27. T piece
[0072] 28. Membrane sealing
[0073] 29. Membrane sealing
[0074] 30. Inner tunneled catheter
[0075] 31. Flushing and/or cooling fluid
[0076] 32. Sealing thread
[0077] 33. Laser applicator

Claims

1. A laser application set to treat tumors in which the distal end of a tunneled catheter (17) from synthetic materials, preferably PE, FEP, PTFE, is air- and fluid-tight sealed and movably guides an optical waveguide (33), characterized in that an introducer tube (6) with a closely fitting interior stylet (12) is provided and a tunneled catheter (17) is fitted with a closely fitting internal stylet (20), in which, upon removal of the stylet (12) from the introducer tube (6), the tunneled catheter (17) with the internal stylet (20) can be closely fitting inserted into the introducer tube (6) and projects from the distal end of the tunneled catheter (17) and in which the optical waveguide (33) can be inserted after the removal of the internal stylet (20) from the tunneled catheter (17).

2. A laser application set according to

claim 1

, characterized in that the introducer tube (6) and the stylet (12) are open at their distal and proximal ends.

3. A laser application set according to

claim 1

, characterized in that the distal end of the tunneled catheter (17) is fitted with a tunneled catheter tip (21) and has an opening at its proximal end.

4. A laser application set according to

claim 1

, characterized in that the introducer tube (6) and the tunneled catheter (17) are each provided with marks (18) and (11) so that the tunneled catheter (17) projects 30 mm beyond the distal end of the introducer tube (6) upon introduction into the introducer tube (6).

5. A laser application set according to claims 1 and 4, characterized in that the marks (11,18) are arranged at a distance of 1 cm from each other, with the introducer tube (6) being marked along its entire length.

6. A laser application set according to at least one of the aforementioned claims, characterized in that the proximal end of the introducer tube (6) is equipped with a T piece (9), with a silicone lamella (10) being placed between the T piece (9) and the introducer tube (6) and an external thread (13) fitted to the opposite side, with an interior membrane (16) and a hose lead (8) at the T piece (9) with a three-way faucet (7) fitted to its end.

7. A laser application set according to at least one of the aforementioned claims, characterized in that the stylet (12) is equipped with a grip end (14) with an internal thread which, in conjunction with the external thread (13) of the introducer tube (6), enables the locking of the stylet (12).

8. A laser application set according to at least one of the aforementioned claims, characterized in that the introducer tube (6) and the stylet (12) are hollow and from a material which is suitable for the MRT process, preferably PE, FEP, PTFE, etc.

9. A laser application set according to at least one of the aforementioned claims, characterized in that the stylet (12) in locked state projects by approx. 10 mm from the distal end of the introducer tube (6) and has an open stylet tip (15).

10. A laser application set according to at least one of the aforementioned claims, characterized in that the internal stylet (20) is made of a wire, which preferably is from a paramagnetic material, and is enclosed by a synthetic sheathing.

11. A laser application set according to

claim 1

, characterized in that a tunneled catheter (17) has an inner tunneled catheter (30), and a firm connection between the two catheters (17 and 30) can be made, and a space exists between the tunneled catheter (17) and the inner tunneled catheter (30), in which a laser applicator (33) is movably arranged.

12. A laser application set according to

claim 11

, characterized in that, in order to establish a firm, separable connection, a connection piece (22) is arranged at the tunneled catheter (17) and a locking piece (23) at the inner tunneled catheter (30), in which the connection piece (22) is provided with a sealing thread (32).

13. A laser application set according to claims 11 and 12, characterized in that locking piece (23) is provided with a membrane sealing (28) which is connected to a T piece (27) by means of a connector (24).

14. A laser application set according to claims 11 and 12, characterized in that a locking piece (23) is provided with a membrane sealing (29) which is connected to a T piece (26) by means of a connector (25).

15. A laser application set according to claims 13 and 14, characterized in that a pump to convey a flushing and/or cooling agent (31) is connected to the T piece (27 and 26).

16. A laser application set according to

claim 12

, characterized in that the flushing and/or cooling agent (31), which is conveyed via the inner tunneled catheter (30) into the tunneled catheter (17) is preferably sterile isotonic sodium chloride solution.

17. A laser application set according to

claim 12

, characterized in that the inner tunneled catheter (30) ends 5 mm before the tunneled catheter tip (21) at the distal end.

18. A laser application set according to

claim 12

, characterized in that the inner tunneled catheter (30) is designed in such a manner that a backflow of the flushing and/or cooling agent is ensured between the tunneled catheter (17) and the inner tunneled catheter (30).