Patent Publication Number: US-2023142426-A1

Title: Apparatus And Method For Controlling Laser Thermotherapy

Description:
RELATED APPLICATIONS 
     This application is a continuation of and claims priority to U.S. Pat. Application Serial No. 16/470,129, filed Jun. 14, 2019 entitled Apparatus And Method For Controlling Laser Thermotherapy, which is a U.S. National Phase of and claims priority to International Patent Application PCT/EP2017/082942, International Filing Date Dec. 14, 2017 entitled Apparatus And Method For Controlling Laser Thermotherapy, which claims priority to European Application No. EP16204195.8 filed Dec. 14, 2016, entitled Apparatus And Method For Controlling Laser Thermotherapy, all of which are hereby incorporated herein by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     This invention pertains in general to the field of interstitial thermotherapy of a treatment lesion associated with at least an area of tissue, such as a tumour. More particularly the invention relates a system for controlled heating and destruction of cancer using a heat source. Even more particularly the invention further relates to arranging a heat source in the tissue to be treated using a slideable sleeve. 
     DESCRIPTION OF THE PRIOR ART 
     It is known in the art that a tumour may be destroyed by heat, such as thermotherapy. One of the most common thermotherapy techniques is interstitial laser hyperthermia, which destroys tumours by absorption of light. Early experimental and clinical studies used an Nd-YAG laser and bare end fibres inserted into the centre of a tumour. Most of these lacked adequate control of the tissue effect. Methods to improve lesion size included multi-fibre systems, diffuser type fibres and vascular inflow occlusion. However, the standard application of interstitial laser hyperthermia results in vaporisation and carbonisation of tissue and relatively unpredictable tissue damage and lesion size. 
     The treatments are mostly controlled by measuring the temperature either close to the emitting area to avoid over heating close to the heating probe, which means that the control over the size of the treatment lesion is very limited. Another way of controlling the temperature is to insert one or more separate leads having temperature sensor in and/or outside the boundaries of the tumour. This may have both practical and ethical disadvantages. Ethically, more sticks have to be conducted in and around the tumour which may be painful for the patient and increase the risks of track seeding. Practically, it may be hard to arrange the different leads and the temperature sensors at the right positions which may affect the treatment negatively. 
     Studies from rats and humans have shown that heat treatment of cancer may give rise to an anti-tumour immunologic effect. If the dying tumour cells release uncoagulated tumour antigens, these antigens may produce an immune response when presented to the immune system of the host. Thus, the treated tumour will not only be destroyed but the immune effect will destroy remaining tumour, locally or at distant sites, including lymph nodes. The immunologic effect contributes to the selective tissue damage and the relatively small release of growth factors. The low treatment morbidity gives the possibility to use chemotherapy in a more efficient way since chemotherapy can be started before or at the time of local therapy. 
     Until now there has been no real way of fully controlling and/or optimize the treatment lesions in an easy way for the practitioner without the drawbacks of the prior art. This has implications on the possibilities to obtain an optimised treatment for the patients. The current systems and the associated drawbacks also affect the possibilities of obtaining and controlling the immunologic effect. Thus, improved control of heat stimulation to optimise the treatment lesion would be advantageous and may increase patient safety. An improved control of the treatment may minimise vaporisation and carbonisation of tissue surrounding the heat source and the adverse effects associated therewith. Further, an improved control over the treatment lesion may improve the possibilities to obtain an immunologic effect. For treatments with the goal of achieving coagulative temperatures the lack of accurate monitoring of the progression of necrotised tissue over time is a limiting factor. To facilitate this, a well-defined temperature measuring technique inside the treatment volume is needed. 
     SUMMARY OF THE INVENTION 
     Accordingly, examples of the present disclosure preferably seek to mitigate, alleviate or eliminate one or more deficiencies, disadvantages or issues in the art, such as the above-identified, singly or in any combination by providing an apparatus, a system, and a method for controlling a heat treatment of a tumour for providing treatment of a tissue, such a tumour, according to the appended patent claims. 
     The apparatus, system and method disclosed herein may be used for controlling a process for irreversibly tissue damage, such as a tumour, for treatment purpose. The damage may be obtained by ablation for removing tissue by vaporisation, such as evaporation, or sublimation. Another example is to achieve coagulative temperatures without monitoring the progress of necrotised tissue over the time of the treatment, such as focal laser ablation (FLA), sometimes also referred to as laser-induced interstitial thermotherapy (LITT). The treatment may also be improved by obtaining an anti-tumour effect, such as an immunologic effect. The anti-tumour effect may be a local, distant or combined local/distant effect following local tumour destruction. The anti-tumour effect is triggered by antigens and may destroy any part left of a treated tumour but may also destroy other untreated tumours in the patient. Thus, the effect may be seen as a “vaccine” against a tumour (abscopal effect). The antigens are a result of a treatment causing cell death but without coagulating/denaturation of tumour antigens. 
     According to aspects of the disclosure, an apparatus for performing thermotherapy on at least a portion of tissue, such as at least a portion of a tumour, is described. The apparatus comprises a heating probe which comprises an energy emitting area. The heating probe is connectable to an energy source for heating the portion of tissue by the energy emitting area. The apparatus further includes a sleeve and the heating probe is arrangable in the sleeve, and the sleeve is configured to be slid along the heating probe in a distal and/or proximal direction for allowing positioning of the energy emitting area in the portion of tissue for controlling the thermotherapy. 
     This arrangement has an improved accuracy and makes it easier to positioning the energy emitting area at the right location in the portion of tissue to be treated. 
     The heating probe may use radiofrequency (RF), microwave frequency (MW), or preferably a laser for heating the tissue by the energy emitting area. 
     In some examples, the sleeve includes at least one temperature measuring element. By sliding the sleeve with the temperature measuring elements in a distal and/or proximal direction, the temperature measuring elements may be positioned at an optimal distance in relation to the energy emitting area. This arrangement has an improved accuracy for controlling the thermotherapy and the size of the treatment lesion compared to using a temperature sensor positioned outside the portion of tissue to be treated by a separately inserted lead. The size of the treatment lesion is determined by the distance between an energy emitting area of a heating probe and approximately a point in the tissue where the temperature is measured and selected to be within a target temperature. One reason is that the temperature sensor will be aligned with the emitting area which can be very hard to achieve when positioning a sensor outside the tumour using a separate lead. When positioning a temperature sensor outside the tumour using a separate lead, the temperature sensor will most likely not end up aligned with the emitting area of the heating probe but instead be positioned either too deep, shallow or at a distance too far away. Another advantage is that it is not needed to re-insert the lead with the temperature sensor if the distance between the heating probe and the temperature sensor of the first insertion was considered not good to achieve an optimal treatment lesion. 
     A further advantage of having the temperature measuring elements arranged in the sleeve, which can be made in a plastic material, is that the temperature measuring points are isolated and will not be affected by a separate lead, which is often made of metal, used for positioning the temperature sensor. By having them isolated the temperature measuring will be faster and/or more accurate as, for example, the temperature measuring elements will not be cooled by the lead as in the case of using a separate lead for positioning the temperature sensor. 
     In some examples of the disclosure is the at least one temperature measuring element arranged in a channel of the sleeve. The sleeve may thereafter be heated and will shrink around the at least one temperature measuring element. Alternatively, in some examples, the sleeve may comprise two shrink tubing concentrically arranged. The temperature measuring elements 20 may be arranged between the two tubes. The tubes may thereafter be heat shrunk. Alternatively, in some examples at least one temperature measuring element braided or woven into the sleeve. 
     In some examples of the disclosure, the heat probe comprises a fibre and the light emitting area of the fibre is at least partially a diffuser. For example, in some examples the diffuser is a radial fibre. In some other examples, the diffuser is a structured writing in a core and/or cladding and/or buffer of the fibre. 
     By using a diffuser, the radiation profile can be varied compared to using a bare end fibre without a diffuser. For example, if the diffuser is a radial fibre more than one discrete radial radiation point may be used. Each of the radiation point may have the same effect or the effect could differ between the radiation points to obtain a specific radiation profile. Another aim may be to obtain a suitable power density. The radiation profile and/or the power density will affect the treatment and/or the shape of the treatment lesion. The same applies when using a diffuser which is made from a structured writing in a core and/or cladding and/or buffer of the fibre. By changing the pattern, the position, and/or the density of the writing, different radiation profile or power density may be obtained which may be used to optimise the treatment of the portion of tissue, such as a portion of a tumour. 
     In some examples of the disclosure the sleeve is an introducer catheter. 
     In some examples of the disclosure are at least two temperature measuring elements arranged at the same transverse plane of the sleeve. This may be done for redundancy to be able to measure the temperature using at least two temperature measuring elements arranged at the same distance from the light emitting area. Should one of the at least two temperature measuring elements give a false value or no value, the other temperature measuring elements may be used instead of the one being broken or damaged. This will improve patient safety and decrease the risk of having to re-insert a new sleeve and heating probe. 
     In some examples of the disclosure is the emitting area of the heating probe covered by a capillary. The capillary may improve the thermostable properties of the heating probe and keep the emitting area intact at when the surface of the capillary is subjected to high temperatures. The capillary may be bonded and sealed to the fibre or the heating probe by fusing, and/or adhering, using for example glue, and/or shrink tubing. When the heat probe includes a fibre, an advantage of fusing the capillary being a glass capillary to a bare end of the fibre is that a very thermostable bond between silica against silica is obtained at the distal end which is exposed to high temperature. Thereby further improving the thermostable properties of the heating probe and to keep the emitting area intact at high temperatures. 
     In some examples of the disclosure a hub is used to lock the sleeve and the heating probe when right position, for example when an optimal distance between the at least on temperature element relation to the energy emitting area is found. By having one part of the hub located at the proximal end of the sleeve and a second part of the hub located at the heating probe the two can be fastened together before sliding the sleeve along the heating probe to find the optimal location for the temperature measuring elements. When the right position has been located a locking member, preferably a valve, such as a haemostatic valve, which is part of the hub, may be used to lock the position of the heating probe, such as the fibre, and the sleeve before starting the treatment. 
     The temperature sensor in the sleeve may be combined with external temperature measuring points, e.g. when sensitive anatomical structures need to be protected. This can serve as a guard shutting off the heat source at a predetermined level to avoid damage to the sensitive structure. 
     In a further aspect of the disclosure, a system for performing thermotherapy on at least a portion of tissue, such as at least a portion of a tumour, is disclosed. The system includes a heating probe which comprises an energy emitting area connectable to an energy source for heating the portion of said tissue by the energy emitting area. The system also includes a sleeve. The system may also include means for measuring a temperature in said portion of tissue and a display unit for indicating a measured temperature from the means for measuring a temperature. The heating probe is arrangeble in the sleeve the sleeve is configured to be slid along the heating probe in a distal and/or proximal direction for positioning the energy emitting area in the portion of tissue to be treated for controlling the thermotherapy. 
     The temperature displayed on the display unit may be used for controlling the energy to the energy emitting area and thereby controlling the thermotherapy. 
     If the means for measuring a temperature are temperature measuring elements arranged in the sleeve, the displayed temperature may be used to find the optimal distance between the energy emitting area and the temperature measuring elements. 
     When the goal of the treatment is to coagulate tissue the temperature sensor in the sleeve is spatially very well defined and the distance to the heat source is very accurate. Using well known bioheat algorithms tissue damage over time may therefore be monitored. 
     In some examples, another way of achieving an improved accuracy when measuring the temperature during a treatment is disclosed. This includes using Magnetic Resonance Imaging to obtain a 2D or 3D temperature map of the treatment area. A region of interest (ROI) may be defined by determining a point at a distance, such as at the tumour boarder, from the emitting area. This region will define a treatment lesion and the temperature in this ROI may be used to control the heat source in order to maintain the temperature at a predetermined value. Other regions in the 2D temperature map of the MR Image may also be defined to serve as an automatic safety function shutting down the heat source if a threshold temperature is reached. 
     In some examples of the disclosure, the system includes a control unit for controlling the emitted energy so that the measured temperature is kept within a target temperature between 40 to 60° C., such as, 40 to 55° C., such as 42 to 50° C. The temperature may, for example, be indicated as a graph on the display. 
     Controlling the heating and the treatment of the tumour by monitoring the temperature at the edge of the treatment lesion and to keep the monitored temperature stable in the identified range has shown to give a god treatment of the treatment with improvements related to safety and limited adverse effects for the patient, such as minimise vaporisation and carbonisation of tissue surrounding the heat source and the adverse effects associated therewith. This relates for example to focal laser ablation (FLA) where it is utilized that the extension of thermal tissue damage depends on both temperature and heating duration. Cell viability is in relation with thermostability of several critical proteins. Irreversible protein denaturation may occur around 60° C. While over 60° C., coagulation is quasi-instantaneous, between 42 and 60° C., a thermal damage is obtained with longer heating periods. The area submitted to supraphysiological hyperthermia less than 60° C. will develop coagulative necrosis in 24 to 72 h after treatment. 
     Additionally, by keeping the temperature at the edge of the treatment lesion within the range 42 and 50° C., such as 44 to 48° C., range has been shown to have the prospect of providing an anti-tumour immunologic effect against the treated cancer, i.e. immunostimulating laser thermotherapy. 
     In another aspect, a method of performing thermotherapy on at least a portion of a tissue site is disclosed. The method includes arrange a heating probe having an energy emitting area in a sleeve. Sliding the sleeve along the heating probe in a distal and/or proximal direction for positioning the energy emitting area in the portion of tissue. Emitting energy from the emitting area of the heating probe for heating the portion of tissue for controlling the thermotherapy. 
     In some examples, the method includes measuring a temperature in a portion of tissue using a temperature measuring element. The temperature measuring element may be inserted into the tissue, such as a temperature sensor, such as a thermistor/thermocouple, and/or be an external device, such as Magnetic Resonance Imaging (MRI) may be used to obtain a 2D or 3D temperature maps of the treatment area. 
     In some examples, the measured temperature is used for controlling the emitted energy from the heating probe. 
     In some examples, the temperature measuring element is arranged in the sleeve and is positioned at a distance from the energy emitting area by sliding the sleeve along the heating probe. 
     It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other aspects, features and advantages of which examples of the disclosure are capable of will be apparent and elucidated from the following description of examples of the present invention, reference being made to the accompanying drawings, in which 
         FIG.  1    is a schematic illustration over an exemplary apparatus for controlling a heat treatment of tissue, such as a tumour; 
         FIG.  2    is a schematic illustration of an exemplary setup of an apparatus for heat treatment of tissue; 
         FIGS.  3 A to D  are a schematic illustration of an exemplary introduction system and heat probe; 
         FIGS.  4 A to  4 B  are a schematic illustration of positioning of a temperature sensor integrated into a sleeve, such as an introducer; 
         FIGS.  5 A to D  are a schematic illustration of an introducing system with a hub. 
         FIG.  6    is a schematic illustration of a probe and introducer arranged in a tumour for obtaining a lesion; 
         FIG.  7 A  and B are a schematic illustrations of a capillary arranged around a diffusing fibre distal end; and 
         FIG.  8    is a schematic illustration of a method for heat treatment of tissue, such as a tumour. 
     
    
    
     DESCRIPTION OF THE PREFERRED EXAMPLES 
     Specific examples of the discloser will be described with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein; rather, these examples are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. The terminology used in the detailed description of the examples illustrated in the accompanying drawings is not intended to be limiting of the disclosure. In the drawings, like numbers refer to like elements. 
     The following description focuses on examples applicable to a device, system, and method for controlling thermotherapy of tissue. The thermotherapy is controlled by controlling a size of a treatment lesion covering at least a portion of tissue to be treated, such as a portion of a tumour. Preferably the treatment lesion is sized to the whole tissue area to be treated, such as a tumour, by positioning the temperature measuring element used for controlling the treatment outside the tissue area. Preferably the temperature measuring element used for controlling the treatment is positioned about 2 to 5 mm outside the boundary of the tissue to be treated, such as a portion of a tumour, i.e. 2 to 5 mm outside the treatment lesion. The size of the treatment lesion may thereby be determined by the distance between the energy emitting part of the probe and the point in the tissue where the temperature is selected to reach a target temperature, such as a target temperature between 40 to 60° C. In particular, the disclosure relates to a device, system, and method for obtaining coagulative temperatures and accurately monitoring the progression of necrotised tissue over time or obtaining an anti-tumour immunologic response by thermotherapy of at least a portion of a tumour. However, it will be appreciated that the invention is not limited to this application but may be applied to other areas of thermotherapy treatment of tumours. 
     In an example according to  FIG.  1   , a schematic illustration over an exemplary system  1  for thermotherapy of tissue, such as a tumour, is illustrated. The system  1  is especially developed for controlling the thermotherapy by controlling the size of a lesion covering at least a portion of a tumour. The system  1  may in some examples be used for controlling immunostimulating laser thermotherapy. 
     The system  1  comprises a control unit  50  which includes a temperature reading unit  51  configures to receive temperature data from a temperature measuring element  20 . The temperature measuring elements may be a temperature sensor, such as a thermistor/thermocouple. The control unit may be a computer, a microprocessor or an electronic circuit for converting an input signal to an output signal. The control may for example be performed using a feed-back loop. In some examples of the system, the temperature measuring element  20  is arranged in a sleeve. The temperature measuring element  20 , such as thermistor/thermocouples, may be arranged in a channel of the sleeve, such as a multi-lumen sleeve. The sleeve may be heat shrunk after the temperature measuring elements have been arranged in the channels of the sleeve. Alternatively, in some examples, the sleeve may comprise two shrink tubing concentrically arranged. The temperature measuring elements  20  may be arranged between the two tubes. The tubes may thereafter be heat shrunk. Another alternatively, in some example, the temperature measuring element  20  may be braided or woven into the sleeve. 
     Alternatively and/or additionally to have the temperature sensors arranged in the sleeve, Magnetic Resonance Imaging may be used to obtain a 2D or 3D temperature maps of the treatment area. A region of interest (ROI) may be defined by determining a point at a distance, such as at the tumour boarder, from the emitting area. This region will define a treatment lesion and temperature in this ROI may be used to control the heat source in order to maintain the temperature at a predetermined value. Other regions in the 2D temperature map of the MR Image may also be defined to serve as an automatic safety function shutting down the heat source if a threshold temperature is reached. 
     When using an external temperature measuring sensor, such as a Magnetic Resonance Imaging system, instead of temperature measuring elements arranged in the sleeve, the sleeve probe arrangement is used for improving and making it easier to positioning the heating area in the tissue. 
     A heating probe  10  having an energy emitting area is arrangable in the sleeve. The heating probe  10  may comprise a fibre having a light emitting area at the distal end, wherein the distal end is configured to be interstitially arranged in the tumour. Alternatives to a fibre may be to use radio frequency RF) or Microwaves (MW) to heat the tissue by the energy emitting area. In some examples, the heating probe  10  has capillary arranged over the energy emitting area, such as the light emitting area. Wherein the capped end of the fibre is the distal end, and wherein the distal end is configured to be interstitially arranged in the tissue, such as the tumour. The capillary may, especially when a fibre is used as a heat probe, improve the heat and mechanical stability of the heat probe. In a further example, the light probe is only a fibre having a light emitting area at the distal end, wherein the distal end is configured to be interstitially arranged in the tumour. 
     When in use, the sleeve may be movably slid along the heating probe  10  in a distal and/or proximal direction to allow positioning of the temperature measuring element  20  at the right distance in relation to an energy emitting area of the heating probe  10  for controlling the thermotherapy by controlling the size of the lesion. The sleeve may be a sleeve arranged around the heating probe  10 . The heating probe  10  and the sleeve may be positioned inside an introducer when performing the thermotherapy. Alternatively, the sleeve may be the introducer and the heating probe  10  is arranged inside the introducer when performing the thermotherapy. 
     Additionally, in some examples of the system the sleeve may have a plurality of temperature measuring elements,  20 ,  30 ,  40  arranged in the sleeve. The plurality of temperature measuring elements,  20 ,  30 ,  40  may be arranged spaced apart along the sleeve. When using a plurality of temperature measuring elements,  20 ,  30 ,  40 , the number of temperature measuring elements may be any number larger than 1, such as 2 to 20, such as 2 to 15, such as 2 to 10, such as 2 to 5. 
     Alternatively, in some examples, at least temperature measuring elements,  20 ,  30 ,  40  may be arranged at the same position instead of being spaced apart. This may be done for redundancy to be able to measure the temperature using at least two temperature measuring elements,  20 ,  30 ,  40  arranged at the same distance from the emitting area, such as a light emitting area. Should one of the temperature measuring elements,  20 ,  30 ,  40  give a false value or no value, the other temperature measuring elements,  20 ,  30 ,  40  may be used instead of the one being broken or damaged. 
     Alternatively, in some examples the temperature measuring elements  20 ,  30 ,  40  may be arranged in the heating probe  10  instead of the sleeve. In some examples, temperature measuring elements,  20 ,  30 ,  40  may be arranged in both the sleeve and the heating probe  10 . Additionally, in some examples, the system  1  may include further external temperature measuring points. These external temperature measuring points may be positioned, for example, next to sensitive anatomical structures that need to be protected from high temperature. These external temperature measuring points may therefore serve as guards shutting off the heat source at a predetermined level to avoid damage to the sensitive structure. 
     The control unit  50  further comprises a power controlling unit  52 , such as an energy source, for controlling the energy emitted by the heat probe  10 . The energy causing the heating of the tissue may be emitted using for example RF technology or laser technology. Laser technology may be preferred as it has been shown to improve the control and heating of the tissue to be treated thereby improving the accuracy of optimizing the treatment lesion.  FIG.  2    illustrates a schematic drawing of a system for thermotherapy of tissue, such as a tumour. The system comprises a control unit  100 . The control unit  100  may for example be a computer connected to power control unit to be connected to a heating probe  170 . The heating probe could be an RF probe, a MW probe, or preferably an optical fibre being connectable to a laser unit. The control unit may also include a temperature reading unit to be connected to temperature measuring elements  190   a ,  190   b . The control unit  100  may further include a display unit  110  for displaying information to a practitioner. The information could be, for example, current measured temperature; time lapsed of the treatment; graphs showing changes in the measured temperature over time; size of the lesion; and the power to the heating probe  170 . The control unit further includes an input unit  120 , such as a keyboard, a computer mouse, a touch pad, or a touch screen. The control unit  100  may further have a first port  150  for connecting the heating probe  170  to the control unit  100 . The control unit  100  may also have a second port  140  for connecting at least one temperature measuring element  190   a ,  190   b , to the control unit  100 . 
     In the system illustrated in  FIG.  2   , a heating probe  170  is connected to a control unit  100  via the port  150 . The heating probe may be an RF probe, MW probe, or preferably is an optical fibre. The heating probe  170  is connectable to an energy source (not shown), such as a laser source, RF source or MW source, controlled by a power control unit (not shown), such as a laser driver, of the control unit  100 .The heating probe  170  has an emitting area at the tip  180 . The emitting area may be a light emitting area. The emitting area is configured to be arranged interstitially in the tissue, such as a tumour, to be treated using the sleeve  160 , such as an introducer. When applying energy for heating the tissue, a treatment lesion  130  is obtained covering at least a portion of the tissue to be treated. 
     In the illustrated examples of the heating probe  170  being an optical fibre, and the emitting area is a light emitting area. The light emitting area may be a bare fibre end or a diffuser. In some examples, the diffuser is a radial fibre. In some other examples, the diffuser is a structured writing in a core and/or cladding and/or buffer of the optical fibre. 
     Additionally, in some examples the emitting area may be covered with a capillary to improve the heat and mechanical stability during the treatment. 
     In the schematic illustration, the heating probe  170  is movably arranged as it may slide in an introducer  160 . In the introducer is at least one temperature measuring element,  190   a ,  190   b  arranged in accordance with the examples given for  FIG.  1    . In the schematic illustrated figure two temperature measuring element,  190   a ,  190   b  are arranged spaced apart along the sleeve. Additionally and/or alternatively, in some examples of the introducer  160 , at least two temperature measuring elements, are arranged at least position  190   a  so that the at least two temperature measuring elements are arranged in the same transverse plane of the sleeve. This may be done for redundancy to be able to measure the temperature using at least two temperature measuring elements arranged at the same distance from the emitting area, such as a light emitting area. Should one of the temperature measuring elements arranged in the same transverse plane of the sleeve give a false value or no value, the other temperature measuring elements may be used instead of the one being broken or damaged. 
     After the introducer  160  and the heating probe  170  have been arranged in the tumour, the size of the treating lesion may be determined by sliding the introducer to increase or decrease the distance between the emitting area and the at least one temperature measuring element  190   a ,  190   b . The at least one temperature measuring elements  190   a ,  190   b  is used for measuring the temperature which is used to control the heating of the tissue by increasing or decreasing the power to the heating probe, such as adjusting the power to the laser unit connected to the control unit  100 . 
     Additionally and/or alternatively, in some examples when at least two measuring points  190   a ,  190   b  are used, if a first measuring point  190   a  measures a to high temperature after adjustment by sliding the introducer  160 , a second measuring point  190   b  having a longer distance to the emitting area may be used for controlling the treatment. 
     Additionally and/or alternatively, in some examples when at least two measuring points  190   a ,  190   b  are used, if a first measuring point  190   a  measures and a to high temperature and a second measuring point  190   b  measures a to low temperature after adjustment by sliding the introducer  160  a virtual point located between the first and the second measurements point  190   a ,  190   b  may be used for controlling the treatment. The temperature of the virtual point may be calculated using the measured temperature at the first measuring point  190   a  and at the second measuring point  190   b . 
     The introducer  160  may in some examples have markers  195  arranged along its length to make it easier to positioning the introducer  160  at the right location by make it visible using ultrasound, MRI, x-ray or other imaging equipment. 
     As previously described in relation to  FIG.  1    , the system illustrated in  FIG.  2    may be combined with a Magnetic Resonance Imaging system which may be used for obtaining a 2D or 3D temperature maps of the treatment area which may be used from defining a treatment lesion. If the system is combined with a Magnetic Resonance Imaging system, the sleeve may not include temperature measuring elements as the temperature at the boarder of the treatment lesion  130  may be measured by the Magnetic Resonance Imaging system. 
       FIGS.  3 A to D  illustrate a schematic example of how to position the sleeve  200 , such as an introducer, and the heating probe  220  in a tumour. 
     Illustrated in  FIG.  3 A  is an introducer  200  and an introducer stylet  210  used for positioning the introducer  200  in the tissue, such as in the tumour. In  FIG.  3 B  the introducer stylet  210  is removed from the introducer  200 . In  FIG.  3 C  the heating probe  220  is arranged in the introducer  200 . In this example, the heating probe  220  is pushed until the tip  230  of the heating probe  200  reached the end of the introducer  200 . The heating probe  220  may have markers  240  arranged along its length to make it easier to positioning the heating probe  220  at the right location by make it visible using ultrasound, MRI, x-ray or other imaging equipment. After the tip  230  of the heating probe  220  has reached the end  250  of the introducer  200  the introducer may be movably slid along the heating probe  220 , as illustrated in in  FIG.  3 D . By sliding the introducer  200  up and down along the heating probe  220  a distance X will be obtained between the first temperature measuring point  260  a and the emitting area  270 . Sometimes, the first temperature measuring point  260  a may not be used, instead the distance X may be determined between the emitting area  270  and a different temperature measuring point, for example any of temperature measuring points  260  b to d. 
     By monitoring the temperature while sliding the introducer  200  up and/or down along the heating probe  220 , the optimal lesion size may be determined. The introducer  200  may have at least one marker  280  for monitoring its position using an imaging modality device, such as ultrasound, x-ray or MRI. The introducer may have further temperature measuring elements  260  b to d spaced with a distance Y along the length of the introducer  200 . 
     When the right distance X between the emitting area  270  and the temperature measuring element  260   a , or  260   b  to d, is found, the introducer is locked at its position by a hub  290  which includes a locking member, such as a valve, such as a haemostatic valve. As previously described, in some examples when at least two measuring points  260   a ,  260   b  to d are used, if a first measuring point  260   a  measures a to high temperature by sliding the introducer  200 , a second measuring point  260   b  to d having a longer distance to the emitting area  270  may be used for controlling the treatment and the size of the treatment lesion. 
     In some examples, a pre-determined distance X is set before positioning the heating probe  220  in the introducer  200 . When the emitting area  270  of the heating probe  220  reached the distal end of the introducer  200  the introducer  200  is pulled back until the introducer  200  and the heating probe  220  is locked together at the hub  290 . In some further examples, the locking includes sematic feedback to indicate to the practitioner that the introducer  200  has been pulled back to the right position. If a further adjustment of the distance is needed the, locking member, such as a valve, of the hub  290  may be opened and the introducer  200  may be further slid in a distal and/or proximal direction until the right position has been found. Thereafter may the locking member, such as a valve, be closed and the introducer  200  and the heating probe  220  may be locked together before the treatment is started. 
     In some examples when at least two measuring points  260   a ,  260   b  to d are arranged in the sleeve, if a first measuring point  260   a  measures a too high temperature and a second measuring point  260   b  to d measures a to low temperature after adjustment by sliding the introducer  200  a virtual point located between the first and the second measurements point  260   a ,  260   b  to d may be used for controlling the treatment. The temperature of the virtual point may be calculated using the measured temperature at the first measuring point  260   a  and at the second measuring point  260   b  to d. 
       FIGS.  4 A and  4 B  are schematically illustrating examples of how to optimize the treatment lesion by sliding a sleeve, such as an introducer,  300  up and/or down along an inserted heating probe  320 . 
     The aim is to optimize the lesion size and to reach the treatment temperature  310 , also called the target temperature. The treatment temperature  310  may be in the range 40 to 55° C., such as 44 to 48° C., such as 46° C. at the edge of the treatment lesion. Controlling the heating of the tumour by monitoring the temperature at the edge of the treatment lesion and to keep the monitored temperature stable in the ranges identified has shown to give a good outcome of the treatment with improvements related to safety and limited adverse effects for the patient, such as minimise vaporisation and carbonisation of tissue surrounding the heat source and the adverse effects associated therewith. Additionally, keeping the temperature at the edge of the treatment lesion within these ranges has been shown the prospect of providing an anti-tumour immunologic effect against the treated cancer, i.e. immunostimulating laser thermotherapy. 
     In  FIG.  4 A , the initial distance between the emitting area  370  of the heating probe  320  and a temperature measuring element  360  arranged in a sleeve, such as an introducer,  300  is X mm. The sleeve  300 , may also have a marker  380  for visualizing the position of the distal end of the sleeve  300 . If the temperature monitored with the temperature measuring element  360  is determined to increase too fast by observing the temperature curve  330  on a display, the sleeve  300  may be slid so that the distance between the emitting area  370  and the temperature measuring element  360  increases to a distance of X+Y mm. The treatment lesion may in this example be made larger than initially planned for, therefore providing an optimized treatment and keep the target temperature  310  stable. 
     In  FIG.  4 B , the initial distance between the emitting are  370  of the heating probe  320  and a temperature measuring element  360  arranged in a sleeve, such as an introducer,  300  is X mm. The sleeve  300 , may also have a marker  380  for visualize the position of the distal end of the sleeve  300 . If the temperature monitored with the temperature measuring element  360  is determined, by watching the temperature curve  330  on a display, to increase too slowly or the target temperature  310  may not be reached, the sleeve  300  may be slid so that the distance between the emitting area  370  and the temperature measuring element  360  decreases to a distance of X-Y mm. Hence the treatment lesion may be made smaller to be able to optimize the treatment and to keep the target temperature  310  stable. 
     In  FIGS.  4 A and  4 B  the illustration shows that the optimization is done with respect to the most distal temperature measuring element. As previously described, sometimes it may be more practical to use another temperature measuring element or to use a virtual point located between two temperature measuring elements. 
     Another reason for using a temperature measuring element for optimizing the treatment lesion and for controlling the treatment than the most distal temperature measuring element is that the more distal one may be positioned inside the treatment lesion. The one or more temperature measuring elements positioned inside the treatment lesion, such as inside the tumour, may be used for measuring and controlling other parameters. For example, the temperature measuring element positioned inside the treatment lesion may be used for detecting bleeding and/or carbonization and/or coagulation. 
       FIGS.  5 A to  5 D  are illustrating a sleeve system having a hub, the sleeve system may also be an introducing catheter system. The sleeve system with the hub illustrated in  FIGS.  5 A to  5 D  may be used with any of the arrangements described and illustrated in relation to  FIGS.  1  to  4   . 
       FIG.  5 A  is illustrating an introducer stylet  400  having a connector  410  comprising at its proximal end means for fastening  410  the connector to a hub and means for releasing  420  the connector from a hub.  FIG.  5 B  is illustrating a sleeve  430 , such as an introducing catheter. The illustrated sleeve  430  may have markings  435   a ,  435   b  for visualizing the positioning of the sleeve in tissue using an imaging modality device, such as ultrasound, x-ray or MRI, but other modalities may also be used. In the sleeve  430 , temperature measuring elements (not illustrated), such as thermistor/thermocouples, may be arranged. The temperature measuring elements may be arranged in channels of the sleeve. The sleeve  430  may be heat shrunk after the temperature measuring elements have been arranged in the channels of the sleeve. In other examples, the sleeve  430  may comprise two shrink tubing concentrically arranged. The temperature measuring elements may be arranged between the two tubes. The tubes may thereafter be heat shrunk. Alternatively, in some example, the temperature measuring elements may be braided or woven into sleeve. 
     The sleeve has a hub  440  attached to its proximal end. The hub  440  has an opening  450  for allowing a stylet as illustrated in  FIG.  5 A  or a heating probe to be introduced into the sleeve  430 . The hub may also comprise a protruding element  445  for the fastening means, such as the fastening means  415  of the connector  410  at the proximal end of the stylet  400 , to hook to and thereby locking the connector to the hub  440 . By pressing the releasing means of a connector, such as the releasing means  420  at the connector  410  at the proximal end of the stylet  400 , the connecter can be removed from the hub  440 . 
       FIG.  5 C  is illustrating a second hub  500  which comprises of two parts, a connector  460  and a locking member  480 , such as a valve, such as a haemostatic valve. The connector  460  is similar to connector  410  of the stylet and comprises fastening and releasing means  465  for connecting the second hub  500  to the hub  440  at the distal end of the sleeve. The locking member  480  comprises an opening  485  at the proximal end for inserting a heating probe (not illustrated). In  FIG.  5 C , the second hub  500  is illustrated as comprising two parts wherein, the distal end has a protruding member  490  to be inserted into an opening  470  of the connector  460 . These two parts may be assembled and delivered as one unit. Alternatively, the hub  500  may be molded as a single unit instead of being two parts that will be combined. 
       FIG.  5 D  is illustrating a cross-section of the second hub  500  after the connector  460  and the locking member  480  has been combined.  FIG.  5 A  is illustrating that the fastening and releasing means  465  includes means for fastening  466  the second hub  500  to the hub  440  of the sleeve by hooking into the protruding element  445 .  FIG.  5 D  also illustrates that the fastening and releasing means  465  includes means for releasing  467  the second hub  500  from the hub  440  of the sleeve by pressing the means for releasing  467 . This type of fastening and releasing means used for the second hub  500  and the stylet  400  allows for a simple and safe way of fastening and releasing the stylet  400  or second hub  500 . 
     In  FIG.  5 D  a lumen  486  is illustrated to go through the locking member  480 , such as a valve, and thereby through the second hub  500 . The heating probe may be arranged in this lumen  485  during the treatment. By locking the locking member  480 , such as closing a valve or closing a haemostatic valve, the heating probe will be locked into its position in the lumen  486 . After the heating probe has been arranged in the lumen  486 , the heating probe may be arranged in the sleeve  480  after the sleeve has been interstitially inserted in to the tissue, such as a tumour, to be treated. The connector  460  will be fastened to the hub  440 , wherein the locking member  480  may be opened and the sleeve  430  may be slid up and/or down along the heating probe. When the right position of the distance between an emitting area of the heating probe and a temperature measuring element of the sleeve  430  has been found, the locking member  480  may be closed to lock the heating probe and the sleeve  430  into the position, whereinafter the heat treatment may start. 
     The connectors and the hub may be made of a suitable material, for example metal or plastic, such as acrylic. 
     In some examples, a pre-determined distance is set before arranging the heating probe in the sleeve  430  by positioning the second hub  500  at the pre-determined position on the heating probe. When arranging the heating probe in the sleeve  430  and the emitting area of the heating probe has reached the distal end of the sleeve  430 , the sleeve  430  may be pulled back until the hub  440  of the sleeve  430  and second hub  500  of the heating probe is locked together. In some further examples, the locking includes sematic feedback to indicate to the practitioner that the sleeve  430  has been pulled back to the right position and that the hub  440  and the second hub  500  have been locked together. If further adjustments of the distance between the emitting area and the temperature measuring element are needed, the locking member  480 , of the second hub  500  may be opened and the sleeve  430  may be further movably slid in a distal and/or proximal direction until the optimal position is found. Thereafter may the locking member  480  be closed and the sleeve  430  and the heating probe may be locked together before the treatment is started. 
       FIG.  6    is illustrating a sleeve  510  and a heating probe  515  arranged inserted into tissue. The heating probe comprises an emitting area  514  and the sleeve comprises at least one temperature measuring element,  530   a  to c arranged in the sleeve  510 . The arrow  586  illustrates that the sleeve  510  may be slid along the heating probe to obtain a distance between the emitting area  514  of the heating probe  515  and the at least one temperature measuring element  530   a  to c thereby obtaining an optimized size of the treatment lesion  513 . The size of the treatment lesion will have a radius which is about the distance between the centre of the emitting area  514  of the heating probe  515  and the at least one temperature measuring element  530   a  to c of the sleeve  510  used for monitoring the temperature for controlling the energy delivered by the energy source, such as a laser unit, for heating the tissue. As previously described, the treatment temperature at the point for monitoring the temperature, also called the target temperature may be in the range 40 to 60° C., such as 42 to 55, such as 44 to 48° C., such as 46° C. This temperature is monitored at the edge of the treatment lesion. Controlling the heating of the tumour by monitoring the temperature at the edge of the treatment lesion and to keep the monitored temperature stable in the ranges identified has shown to give a good outcome of the treatment with improvements related safety and limited adverse effects for the patients, such as minimise vaporisation and carbonisation of tissue surrounding the heat source and the adverse effects associated therewith. This relates for example to focal laser ablation (FLA) where it is utilized that the extension of thermal tissue damage depends on both temperature and heating duration. For FLA a temperature between 42 and 60° C. is normally used and a thermal damage is obtained with longer heating periods compared to normal laser ablation. 
     Additionally, keeping the temperature at the edge of the treatment lesion within these ranges has been shown prospect for providing an anti-tumour immunologic effect against the treated cancer, i.e. immunostimulating laser thermotherapy. The treatment may preferably be performed for about 30 min after the temperature measuring elements have been positioned at the right distance with respect to the emitting area. Sometimes longer or shorter times may be used. 
     While the sleeve and heating probe are removed, the emitting area may continue to deliver energy to the surrounding tissue, thereby heating the channel which may minimise the risk of track seeding. 
       FIGS.  7 A and  7 B  are illustrating a capillary to be used to protect the emitting area of, in this example, an optical fibre. The emitting area of the optical fibre may either be a bare end fibre or a diffuser. The diffuser may be any type of diffuser but is preferably either a radial fibre or a structured writing in a core and/or cladding and/or buffer of the optical fibre. 
     The optical fibre may be, for example, made of silica or a plastic, or may be any other suitable type of optical fibre. The optical fibre may also be a polymer coated fibre. 
       FIG.  7 A  illustrates a glass capillary  600  covering a bare end fibre  610  which may include a diffuser. The bare end fibre  610  comprises of a fibre core and may also in some examples include a cladding. The tip of the distal end of the fibre  610  may be in some examples flat as illustrated in  FIG.  7 A  or conical. The glass capillary  600  may be bonded  630  to the jacket  620  and/or buffer of the fibre either by fusing or by using an adhesive, and/or by shrink tubing. The space  640  around the bare end fibre  610  may be filled with air. This design of the capillary increases the fibre’s mechanical stability and its resistance to high temperatures. 
       FIG.  7 B  illustrates a similar cap as the one in  FIG.  7 A . The cap is made from a glass capillary  600  covering a bare end fibre  610  which may include a diffuser. The bare end fibre  610  comprises of a fibre core and may also in some examples include a cladding. The tip of the distal end of the fibre  610  may be in some examples flat or conical as illustrated in  FIG.  7 B .. 
     The glass capillary  600  and the fibre  610  are fused together at the point  650  which means that a very thermostable bond between silica and silica is obtained at the distal end which is exposed to high temperatures. The capillary may further include an adhesive  660  to glue and seal the cap. The heating probe itself may comprise the jacket of the fibre made form, for example acrylate, than a layer of, for example, resin and an outer layer made of, for example, PBT. Additionally, in some examples, the glass capillary  600  may be further bonded  630  to the jacket  620  and/or buffer of the fibre by either fusing or using an adhesive, and/or by shrink tubing. 
     At the distal end of the bare end fibre where the emitting area is, the space  640  between the fibre and the glass capillary  600  may be filled with air. 
     This design of the capillary increases the fibre’s mechanical stability and its resistance to high temperatures. The structured writing may include the process of ordered writings in periodically repeated cycles, such as at least two cycles are repeated, along the length of the emitting area of an optical fibre. The structured writing may be made using a manufacturing process wherein micro-modifications are burnt into the core, and/or cladding and/or buffer of an optical fibre. The micro-modifications may be arranged on one or more sectional planes, wherein the sectional planes lie substantially perpendicular to the optical waveguide axis of the optical fibre. The arrangement of the micro-modifications on the sectional plane by one or more parameters from a group of parameters comprising the symmetric arrangement of the micro-modifications, the density of the micro-modifications on the sectional plane, the size of the micro-modifications, the distance of the micro-modifications from the optical waveguide axis, the distance between the micro-modifications, the alignment of the micro-modifications or other parameters, with the aid of which the position and distribution of the micro-modifications or the size or outer form thereof is described. All these parameters will affect the light transmitted through the fibre and the coupling of the transmitted light out of the fibre thereby providing a diffuse radiation of light from the optical fibre. Each cycle may comprise one or more plane. If a cycle includes more than one plane, different shapes of the cycle may be obtained by vary the parameters, such as each cycle has the shape of, for example a cone or a cylinder, wherein the shape of the cycle may be hollow or filled with micro-modifications. The micro-modifications may have different shapes of the cross sections, for example circular, or ellipsoid. All micro-modifications shaped as ellipsoid may have the same orientation or the orientation may differ between the micro-modifications. 
     A diffusor may, for example, include two writing cycles, where two cylinders of lesions are generated which are distinct (not overlapping) and in the core of the fibre. The diffusor may be produced with the buffer stripped away in the area of the diffusor. 
     Another example may be a diffusor with ordered writing, which repeats in a periodic way along the circumference of the core and along the lengths of the diffusor. The diffusor may be produced with the buffer stripped away in the area of the diffusor. 
     A structured diffusor may also be obtained by creating scattering elements, such as microdots, along the fibre axis. The scattering elements may be arranged close to the boundary of the core of the optical fibre and project into the core for radial decoupling of light. The scattering element may be made either by modified refractive index of the core or as recesses along the core surface by a laser manufacturing method. The recess may in some examples be spherical. 
     The diffusor may further have the recess filled with a material, such as air, so that a boundary is formed with the corresponding refractive index between the recess and core. The material may, in some examples, include a scattering material having a matrix of scattering particles embedded therein for scattering light. The scattering material may be applied at least area-wise on the optical fibre, such as being coated with the scattering material. The scattering elements may also be applied in the scattering elements. 
     The scattering elements may be distributed in a peripheral direction and in the longitudinal direction, such as in a spiral, of the diffusor segment of the optical fibre for an even emission of light in a radial direction. The scattering elements may have a variable density, for example the density may increase closer to the distal end of the diffusor. This may be obtained by having the spacing distances decrease towards the distal end. 
       FIG.  8    describes a method  2000  of performing thermotherapy on at least a portion of a tissue site, such as a tumour. The method includes positioning  2001  a sleeve into the tissue to be treated, such as a tumour, wherein the sleeve may include at least one temperature measuring element. Arranging  2002  a heating probe having an energy emitting area inside the sleeve. The heating probe may be an RF probe or MW probe. In some examples, the heating probe includes an optical fibre with a light emitting area. The heating probe is connectable to an energy source for heating the tissue through the energy emitting area. The energy source may be a laser unit. Sliding  2003  the sleeve along the heating probe in a distal and/or proximal direction for positioning the energy emitting area in the tissue to be treated. In the examples, wherein temperature measuring elements are arranged in the sleeve, sliding  2003  the sleeve along the heating probe in a distal and/or proximal direction may be made to find the optimal distance between at least one temperature measuring element of the sleeve and the energy emitting area. This may be done to determine the size of the treatment lesions which will have a radius about the distance between the temperature measuring element and the energy emitting area. In some examples, the temperature may be measured using a Magnetic Resonance Imaging system to obtain 2D or 3D temperature maps of a treatment area. The treatment area may be used to optimize the size of the treatment lesion. 
     Controlling  2004  the thermotherapy by monitoring the temperature at the optimal distance from the emitting area and adjusting the power of the energy source. 
     The optimal distance may be found by checking the temperature at a display while sliding the sleeve along the heating probe. After the optimal distance has been found, the sleeve and heating probe may be locked together to fix the distance by using a hub having a locking member, such as a valve, such as a haemostatic valve. 
     The present invention has been described above with reference to specific embodiments. However, other embodiments than the above described are equally possible within the scope of the invention. Different method steps than those described above, performing the method by hardware or software, may be provided within the scope of the invention. The different features and steps of the invention may be combined in other combinations than those described. The scope of the invention is only limited by the appended patent claims. 
     The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.” The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases.