Patent Application
20110319971
The present invention relates to the field of treatment of the human or animal body by subcutaneous or intracutaneous irradiation by means of electromagnetic radiation. In this field, it relates in particular to a new technical solution for the control of the energy of the electromagnetic radiation applied in the course of a treatment, said solution finding its application in different types of subcutaneous or intracutaneous therapeutic or cosmetic endotreatments, such as lipolysis, endovenous therapy, skin remodelling or skin healing through heating the collagen present in the dermis and/or through thermal stimulation of the fibroblasts to accelerate the production of collagen in the dermis. The invention also has as its object a new method of skin remodelling or skin healing.
In the field of therapeutic or cosmetic treatments of the human or animal body, to date different technical solutions are used based on subcutaneous irradiation of the zone to be treated by means of electromagnetic radiation, and based in particular on irradiation by means of electromagnetic radiation produced in the visible wavelength region for instance, using a continuous laser beam or a pulsed laser beam with different power levels. In these subcutaneous treatments, electromagnetic radiation is introduced under the skin to the zone to be treated, by means for instance of a hollow needle or a cannula, in which an optical fibre is inserted and linked to the adapted source of electromagnetic radiation, for instance a laser.
Treatments by subcutaneous electromagnetic radiation include primarily, but not exhaustively, lipolysis, which consists in destroying, in particular by the effect of heat, the adipose cells present in the hypodermis, by inserting into the hypodermis, at different depths, the distal extremity of the optical fibre, through which the electromagnetic radiation passes. They also include any endovenous therapy, in which electromagnetic radiation is produced in a vein. For laser lipolysis, the following publications can for instance be referred to: U.S. Pat. No. 6,206,873, U.S. Pat. No. 5,954,710 and US 2006/0224148. For endovenous laser therapy, publications U.S. Pat. No. 4,564,011, U.S. Pat. No. 5,531,739 and U.S. Pat. No. 6,398,777 can for instance be referred to.
A major difficulty of these treatments is linked to the risks of irreversibly destroying, through the effect of heat, non-targeted cells in the treated zone, or even in a zone adjoining the treated zone. This risk is dependent not only on the power and the wavelength of the electromagnetic radiation, but also and primarily on the speed with which the electromagnetic radiation spot is provided to the zone to be treated. The latter parameter of the speed of displacement, however, most often depends on a human manual action performed by the practitioner carrying out the treatment and is thus a significant source of risk.
Attempts to resolve this difficulty to date include efforts to control the energy of the electromagnetic radiation applied during treatment. In US patent application 2004/0199151, for instance, a solution is proposed based on measuring the speed of withdrawal of the optical fibre and on an automatic control of the laser power, as a function of the measured speed, so as to maintain a suitable constant treatment energy. Different solutions for measuring the displacement speed of the optical fibre are considered. For instance, specific marks made upon a certain length of the optical fibre are automatically detected or an optical speed measuring device, through which the optical fibre passes, is implemented. This solution has two disadvantages. On the one hand, the measuring means of the displacement speed of the optical fibre are positioned in the field of surgery, which brings about a problem of sterility of these measuring means. On the other hand, this solution does not enable the zone actually treated to be localised, and in particular does not enable the applied energy doses to be mapped at each point of the zone actually treated.
Other control solutions based on external detection of the skin temperature by means of an infrared sensor or by thermosensitive reagents applied on the skin have also been suggested. These solutions are not satisfactory, however, due in particular to the time required for the heat to propagate to the surface of the skin. Once the skin temperature threshold is reached and detected, it is generally too late and irreversible subcutaneous thermal lesions may already have been caused.
International patent application WO 2006/107522 suggests a solution for laser lipolysis, in which the laser beam is introduced into the hypodermis by means of a cannula/optical fibre unit. One objective in this publication is to protect the dermis against the destructive thermal effects of the laser beam by ensuring that the distal extremity of the optical fibre, upon firing, is not situated in the dermis, but rather in the hypodermis, at a sufficient distance from the dermis. To this effect, the depth of the laser shot is controlled by detecting, by means of an external optical sensor, the intensity of the light energy of the shot, which passes through the different layers (hypodermis, dermis, epidermis) and which is visible from the outside because of the sensor. The greater the intensity, the shallower the laser shot. This solution does not, however, enable the energy applied during treatment to be controlled and in particular does not enable the energy doses applied in each point of the zone actually treated to be mapped.
In addition to the above-mentioned subcutaneous treatments, there are also skin heat treatments of the non-invasive type, in the field of dermatology.
In particular, non-invasive heat treatments are implemented to heat the collagen present in the dermis of the skin and/or to thermally stimulate the cells (fibroblasts) producing collagen in order to stimulate collagen production by the fibroblasts in the dermis.
A significant application of these non-invasive heat treatments of the dermis is the remodelling of the skin through collagen in order to reduce or get rid of wrinkles due to ageing or to suppress unsightly aspects of the skin, so-called “orange peel skin”.
U.S. Pat. No. 6,659,999 and US patent application US 2003/0040739, for instance, suggest skin remodelling solutions through collagen based on external electromagnetic radiation of the skin by means of an exolaser, for instance.
The stimulation of collagen production by an external laser can also be used to obtain improved skin healing. A method of skin healing by means of a 815 nm laser is for instance described in the article “Laser Assisted Skin Closure (LASC) by using a 815-nm Diode-Laser System Accelerates and Improves Wound Healing” by A. Capon et al, Lasers in Surgery and Medicine 28:168-175 (2001).
During these heat treatments of the dermis, it is important that sufficient heating of the dermis is obtained, without however reaching a coagulation temperature (of the order of 60° C.), which would destroy the fibroblasts.
A disadvantage of these non-invasive treatments lies in the risks of burning the epidermis. In practice, to avoid these risks of burning, one is forced to combine this heat treatment with an external and local cooling of the epidermis.
According to a first aspect, the invention aims to suggest a new technical solution for the automatic and real-time control of a treatment by subcutaneous or intracutaneous irradiation by means of electromagnetic radiation, with the aim of controlling the energy doses supplied to the treated zone and in particular of avoiding the supply of excessive energy doses or, conversely, the supply of energy doses that are too weak and ineffective for the treatment.
The invention thus has as a first object an automatic control method of a treatment, during which subcutaneous or intracutaneous irradiation by means of electromagnetic treatment radiation and possibly by means of targeted electromagnetic radiation is implemented. This control method comprises the following steps:
For the implementation of the invention, the irradiation spot detected by the sensor can be, depending on the circumstances, the irradiation spot of the electromagnetic treatment radiation or the irradiation spot of the targeted electromagnetic radiation. Nevertheless, the electromagnetic radiation detected by means of the sensor will preferably be the electromagnetic treatment radiation, since this is in practice more powerful than the targeted electromagnetic radiation.
A further object of the invention is a control system of a treatment by subcutaneous or intracutaneous irradiation by means of electromagnetic radiation as defined in claim 10, and a medical device as defined in claim 18 and including said control system.
According to a second aspect, the invention has as an object the proposition of a new skin remodelling or skin healing method through irradiation by means of electromagnetic radiation.
In a characteristic manner according to the invention, irradiation by means of electromagnetic radiation is carried out in the sub-dermal layer. This irradiation by means of electromagnetic radiation in the sub-dermal layer enables the collagen present in the dermis to be heated and/or the production of collagen to be stimulated by heating the fibroblasts.
To date, solutions for heat treatment enabling skin remodelling or skin healing to be obtained have most often been non-invasive. Invasive solutions have certainly also been suggested, in particular in U.S. Pat. No. 5,370,642, but in this case and up to the present, systematic attention has had to be paid to the optical fibre of the endocular laser (endolaser) penetrating into the hypodermis, to a sufficient depth in order for the energy to be supplied at a sufficient distance from the dermis and to avoid any risk of heat damage to the dermis and epidermis.
The invention has the distinction, on the contrary, of attempting to get closer to the dermis and of demonstrating that it is possible to carry out a heat treatment through irradiation by means of electromagnetic radiation supplied to the sub-dermal layer, which is effective for obtaining skin remodelling or skin healing by the collagen in the dermis, without causing irreversible heat damage to the dermis and epidermis.
Other characteristic features and advantages of the invention will appear more clearly upon reading the detailed description hereinafter of several embodiments of the invention given by way of non-limiting and non-exhaustive examples, said description being given with reference to the figures, in which:
a, 5b and 5c represent the image displayed on a screen for the operator at different stages of the treatment method, during the implementation of the steps of the flowchart of
With reference to
To perform subcutaneous laser treatment, for instance to destroy the adipose cells present in the hypodermis (lipolysis), usually an optical fibre is inserted into the hypodermis C, by means of a cannula or hollow needle, after having made a small incision in the epidermis A and the dermis B, where appropriate. This optical fibre is linked at its proximal extremity (the opposite end to the distal extremity of the fibre inserted underneath the skin) to a pulsed or continuous laser source. This laser source can also be replaced by any other type of source enabling the supply of an appropriate electromagnetic treatment radiation, and for instance by a source composed of one of several high-power diodes. Once the optical fibre has been inserted, in order to carry out the treatment, the practitioner displaces the optical fibre while performing laser shots. Two principal techniques are implemented. A first technique consists in carrying out a withdrawal of the fibre in a discontinuous manner, and in performing a longer or shorter laser shot (continuous or pulsed) at each stop. A second technique, more commonly used because it is quicker, consists in carrying out a continuous withdrawal of the fibre at a substantially constant speed and, during this continuous withdrawal, in performing a laser shot (continuous or pulsed) without interruption. In practice, to cover the entire area to be treated, the practitioner must insert the optical fibre several times, in order to position initially the distal extremity of the optical fibre in different points of the zone to be treated and to carry out several withdrawal operations of the optical fibre with laser shots (without necessarily taking out the distal extremity of the optical fibre).
In a similar manner, to perform endovenous therapy by laser or equivalent, it is usual to insert an optical fibre into a vein by means of a cannula or hollow needle, and to treat the inside of the vein by performing laser shots according to one or the other of the above-mentioned discontinuous or continuous techniques.
The system and method of control according to the invention, of which one embodiment will be described in more detail shortly, enables an advantageous control, in this type of endotherapy through irradiation by means of electromagnetic radiation, of the energy of the electromagnetic radiation supplied to the treated zone.
It should be underlined that to date, in the case of subcutaneous laser treatments, in order to avoid the risk of burning of the dermis B and the epidermis C, systematic attention is paid to the insertion of the distal extremity of the optical fibre into the hypodermis to a depth in the hypodermis that is sufficient for the laser shot or equivalent not to be performed in immediate proximity to the dermis B. Because of the control of the energy of the electromagnetic treatment radiation obtained by means of the invention, it is now possible to perform new subcutaneous treatments in proximity to the dermis or in the so-called “sub-dermal” layer, at the interface between the dermis and the hypodermis, even to perform intracutaneous treatments, by positioning the distal extremity of the optical fibre in the dermis.
The control system according to the invention includes a camera 1, enabling a plurality of images l(t) of the treated zone to be successively obtained, at a predefined capturing speed (time interval between two images l(t)).
For each shot, the electromagnetic radiation produced can be of the pulsed or the continuous type.
If appropriate, the operator Op can also regulate the power P(t) of the source 3. In the present text, “power P(t) of the source 3” designates the average power of the source. In the case of continuous electromagnetic radiation, the power P(t) is equal to the instantaneous power of the electromagnetic radiation supplied by the source 3. In the case of electromagnetic radiation of the pulsed type, the average power P(t) is equal to the energy supplied during one second. For instance, for a laser of instantaneous power (Ppeak) of 1000 W and having a pulse width (T) of 150 μs with a repetition rate (f) of 40 Hz:
Similarly, in a known manner, the medical treatment device can include a second electromagnetic radiation source (for instance a second laser source), which is also linked to the optical fibre F and which enables a second, so-called targeted, electromagnetic radiation to be supplied. This targeted electromagnetic radiation is generally of a weaker power than the electromagnetic treatment radiation supplied by the source 3. This targeted electromagnetic radiation is used to localise the subcutaneous or intracutaneous zone that is to be treated by the electromagnetic treatment radiation.
With reference to
With reference to
In the particular example of
The camera 1 is positioned at a distance (d) from the treated zone and shows a predefined viewing angle θ. Preferably, but not necessarily, during the course of treatment, the camera 1 is fixed, the distance (d) and the viewing angle θ being regulated so that the field of vision of the camera 1 covers the entire surface of the zone to be treated. Nevertheless, in another embodiment, the camera 1 can be mobile in order to cover the entire zone to be treated.
The camera 1 is furthermore chosen such that it is sensitive to the wavelength or the range of wavelengths of the electromagnetic radiation that is to be detected.
Preferably, the detected electromagnetic radiation is the electromagnetic treatment radiation supplied by the source 3. Nevertheless, for the implementation of the invention, the detected electromagnetic radiation can also be the targeted electromagnetic radiation.
In the rest of the description, the control of the treatment through irradiation is based on a detection by the camera 1 of the irradiation spot (S) of the electromagnetic treatment radiation supplied by the source 3. In a further embodiment, the control of the treatment by irradiation can be based on a detection by the camera 1 of the irradiation spot (S) of the targeted electromagnetic radiation.
In the majority of cases, the treatment is implemented by a laser or equivalent source having an emission wavelength in the visible range, generally between 600 nm and 1400 nm for the most commonly used lasers. Consequently, most of the time, the camera 1 will be chosen so that it can detect an electromagnetic radiation in the visible or near infrared region. The camera is for instance a matrix camera with charge transfer sensors, generally called a CCD camera (on the basis, for instance, of photosensitive silicon cells in the visible region or of germanium in the near infrared region).
The invention is not, however, limited to this 600 nm-1400 nm range of wavelengths, but can be implemented with radiations outside of this range, for instance with a HF (microwave) or RF (radiofrequency) radiation. In this case, the sensor will be adapted to the radiation wavelength (for instance, matrix sensor based on Schottky diodes).
By way of a non-limiting example, the control method according to the invention can be implemented with a CMOS 500×582 pixel camera enabling an image to be obtained every 0.04 seconds, a viewing angle of θ=70° and a distance (d) between the camera and the epidermis A of 20 cm. The surface visible via the camera in this case is 784 cm2 (28 cm×28 cm). Each pixel thus corresponds to a surface of 0.27 mm2 (0.52 mm×0.52 mm).
During a shot, at the distal extremity of the optical fibre F, the laser beam, when exiting from the optical fibre, forms an irradiation spot S (
The electronic treatment means 2 include a treatment unit, which is programmed to carry out an algorithm, of which several embodiments are shown in the flowcharts of
This algorithm enables the mapping of the linear energy doses supplied in the course of endovenous therapy, during which the optical fibre F is inserted inside a vein and is withdrawn from the vein, either with a continuous movement, during which a shot is carried out without interruption by the operator (Op), or with a discontinuous movement, during which a plurality of successive shots are carried out by the operator (Op) at different positions of the distal extremity of the optical fibre F.
Steps S1 to S3 are calibrating steps of the camera 1, prior to the realisation of the endovenous therapy.
During this first step, the operator Op starts up the camera 1.
Then, the operator Op positions a calibration scale 4 (for instance, a graduated ruler with graduations spaced by a known distance d1) on the zone to be visualised. The electronic treatment means 2 obtain a real image of the zone to be treated (
The real image of the zone to be treated (including the calibration ruler 4) is displayed on the screen 20 for the operator. This image corresponds to
The above-mentioned automatic calibration steps enable the method to be implemented regardless of the above-mentioned distance (d) between the camera 1 and the epidermis A and of the setting of the focal distance of the camera 1. When these parameters remain constant from one treatment to another, it is enough to carry out the calibration of the camera on one single occasion and it is not necessary to repeat the calibration steps prior to each treatment. It should also be underlined that the calibration of the camera 1 is optional for the implementation of the invention and is justified only for the specific embodiments in which a parameter is calculated in function of the width Lij or the surface Sij of a pixel.
Steps S4 to S10 implemented in the course of the treatment will now be described in more detail.
From the above-mentioned signal 31 supplied by the source 3, the electronic treatment means 2 detect whether a shot is in progress or not. If a shot is in progress, the electronic treatment means 2 automatically carry out the following steps S5, S6, . . . .
The electronic treatment means 2 trigger the acquisition of an image l(t) by means of the camera 1 and carry out a filtering of this image l(t) to detect in the image the most luminous pixel(s) forming the most luminous spot p(t) corresponding to the real irradiation spot S. In general, this most luminous spot p(t) forms a light blot, which depending on circumstances can cover several pixels of the image (this is the most frequent case corresponding to the example of the annexed drawings) or only one single pixel pij of the image. This light spot p(t) is not necessarily circular, but in function of the implemented filtering, the detected light blot corresponding to this light spot p(t) can have a non-circular shape.
For instance, for the filtering, a simple thresholding of the level of luminosity (level of grey in the context of a monochrome image) of the all-or-nothing type is implemented, by preserving only those pixels with a level of luminosity superior to a predefined threshold. The dimension of the light spot p(t) will thus depend on the level chosen for the filtering threshold. The higher the filtering threshold, the weaker the dimension (in number of pixels) of the light spot p(t).
The filtering threshold can be fixed and predefined. The values of the parameters can also be manually adjusted by the operator in order in particular to keep track of the depth of treatment. In another embodiment, this filtering threshold can be auto-adaptable and automatically calculated from the luminosity levels of the pixels of the image.
The electronic treatment means 2 automatically calculate the energy eij(t) of the electromagnetic radiation for each pixel pij of the light spot p(t), which has been detected in the previous step by means of the following formula:
in which:
τ is the time interval separating two successive image acquisitions; this parameter is characteristic of the camera 1 that is used and depends on the acquisition speed of the camera 1 (for instance, if the acquisition speed of the camera is 25 images per second, τ equals 40 ms).
In this embodiment, the energy eij(t) calculated for each pixel pij covered by the light spot p(t) is identical.
In a further embodiment, a calculation of the energy eij(t) for each pixel pij covered by the light spot p(t), which is weighted by the light intensity of this pixel pij, can also be carried out.
The electronic treatment means 2 calculate for each pixel pij of the detected light spot p(t) the new linear energy value Eij(t) (energy per unit of length) by means of the following formula:
in which:
During step S7, the electronic treatment means 2 update in the image displayed on the screen 20 the light intensity Iij of each pixel pij corresponding to the detected light spot p(t), from the new value Eij(t) previously calculated, this light intensity Iij being proportional to Eij(t). For instance, in the case of a monochrome image, this light intensity Iij is coded in grey level values from the linear energy value Eij that has been calculated.
For the operator Op a mapping of the electromagnetic energy for each detected irradiation spot (S) is carried out by visualising on the real image of the treated zone acquired by the camera 1 the position of each detected light spot p(t) corresponding to an irradiation spot (S), and the supplied linear energy Eij(t).
The electronic treatment means 2 verify that the linear energy Eij(t) is acceptable, by comparing this value with a predefined threshold (EL max), which if necessary can be regulated by the operator Op.
If the energy supplied by unit of surface Eij(t) is superior to this threshold, the electronic treatment means 2 control the stopping of the source 3 by means of a signal 21 (
If the linear energy Eij(t) is inferior to this threshold, the electronic treatment means 2 carry out step S9.
In a further embodiment, several alarm thresholds can be foreseen. In this case, the above-mentioned threshold (EL max) corresponds to the highest threshold. If a weaker intermediary threshold is detected as having been exceeded (without exceeding the highest threshold EL max), the electronic treatment means 2 do not stop the source 3, but trigger a warning signal 22 (visual and/or audio) for the operator Op, so that the latter may react in real time, for instance by increasing the withdrawal speed of the optical fibre F to decrease the supplied linear energy dose.
This test is identical to the test of the above-mentioned step S4.
If a laser shot is in progress, the electronic treatment means 2 go back to step S5 (acquisition of new image l(t+1), . . . ).
If no shot is carried out by the operator Op (end of treatment sequence), the electronic treatment means 2 display on the screen 20 the last acquired image l(t) of the treated zone with the mapping of the linear energy doses Eu.
By way of example,
This algorithm enables the mapping of the surface energy doses supplied during the course of a lipolysis-type treatment, during which the distal extremity of the optical fibre F is inserted into the hypodermis and is displaced in the usual manner to a layer by the operator (Op) so as to cover a surface to be treated. This algorithm also applies to any treatment by electromagnetic irradiation during which the distal extremity of the optical fibre is inserted and displaced in the sub-dermal layer SD (for instance treatment for skin remodelling or skin healing described hereinafter) or during which the distal extremity of the optical fibre is inserted and displaced in the dermis.
This algorithm is different from the above-mentioned algorithm of
In this algorithm, steps S1 to S3 involving the automatic calibration of the camera 1 prior to the implementation of the treatment, as well as steps. S4, S5 and S9 to S11 are identical to steps S1 to S5 or steps S9 to S11 respectively of the algorithm of
This algorithm of
The calculation of the speed v(t) carried out in step S7 is obtained from two positions [lights points p(t−1) and p(t)] of the irradiation spot (S) in two successive images l(t−1) and l(t), and from the calculation of the distance d(t) (step S6) between these two positions, this distance d(t) being expressed in step S6 in the number of pixels of the image.
In a further embodiment, the treatment algorithm can be modified to be more complete and to implement for a same irradiation treatment by electromagnetic radiation both a mapping of supplied energies (eij(t) or Eij(t)) and a displacement speed v(t) control of the irradiation spot at the distal extremity of the optical fibre (merging of the algorithms of
The solution of the control of a treatment by subcutaneous or intracutaneous irradiation by means of electromagnetic radiation according to the invention is particularly (but not exclusively) adapted to control the new skin remodelling or skin healing method of the invention, an embodiment of which will be described hereinafter.
The main steps of this skin remodelling or skin healing method are the following.
With reference to
The power P(t) of the source 3 or the linear displacement speed v(t) of the irradiation spot S in the sub-dermal layer SD are controlled in such a manner that the temperature in the sub-dermal layer SD is comprised between approximately 45° C. and 55° C., and preferably even between 48° C. and 52° C. A temperature superior or equal to 45° is sufficient to obtain an effective remodelling of the skin (diminution of the depth of wrinkles, remodelling of the epidermal zones that have an “orange peel skin” appearance) or an improved healing of the skin, by a heating of the collagen in the dermis and/or by a heating of the fibroblasts enabling the stimulation of collagen production in the dermis. A temperature inferior to 55° C. means that irreversible heat damage is avoided in the dermis B or in the epidermis A.
Preferably, the power P(t) of the source 3 is weak and inferior or equal to 5 W and the displacement speed v(t) is comprised between 20 mm/s and 50 mm/s.
The choice of the displacement speed v(t) for a given power P(t) depends on the wavelength of the irradiation spot (S).
By way of example, the table I below provides optimal coupling values (P(t)/V(t)) for different wavelengths.
In the range of wavelengths between 800 nm and 1200 nm, the minimum speed v(t) that should be applied is sufficiently slow to be manually implemented without difficulty by an operator Op. Outside this range, however, the minimum speed that should be applied is relatively significant, which makes the treatment riskier, since the slightest slowing down can result in a very rapid overheating of tissues. More generally, the 800 nm-1320 nm range of wavelengths is preferable for the implementation of the method. The method can nevertheless be implemented with wavelengths situated outside this range. More particularly, in a particular embodiment, the method is implemented such that the power P(t) of the electromagnetic radiation source and the linear displacement speed v(t) of the irradiation spot S in the sub-dermal layer SD respect the provision: P(t)=k.v(t), k being a predefined constant.
More particularly, k will be chosen to lie between 0.1 and 0.5, for a power expressed in Watts and a speed expressed in mm/s.
| Number | Date | Country | Kind |
|---|---|---|---|
| 07370014.8 | Aug 2007 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP08/06532 | 8/7/2008 | WO | 00 | 2/8/2010 |
| Number | Date | Country | |
|---|---|---|---|
| 61001320 | Oct 2007 | US |
