Application device for phototherapy

Abstract

A phototherapy applicator 1 (e.g. handpiece) comprises plural optical elements 6 mounted on a support 2, each optical element transmitting radiation from a light source, such as a single laser generat

Description

The present invention relates to an application device for phototherapy. It is known that phototherapy has various applications of medical type, including photo-diagnostic techniques, surgical applications, anti-pathogenic photo-dynamic techniques and photobiomodulation (PBM). The device of the present invention is preferably used in the field of photobiomodulation, although different uses cannot be ruled out. PBM is a non-invasive therapy which uses light to promote positive physiological changes in biological tissues: stimulating healing, reducing inflammation and pain, and regenerating tissues. To date, PBM has been recognised as effective in the treatment of some common complications of oncological therapies, such as oral mucositis induced by chemotherapy and radiotherapy. Despite success in the cure of mucositis, the transfer of the obtained results obtained in vitro and on animals to human beings for other conditions is still complicated. The main challenge lies in the absorption and dispersion of light in skin tissues: when the light is applied on the body surface, its intensity decreases significantly as it penetrates into the tissues. At a depth of 1 cm, there only remains a small percentage of the initial light energy; at 2 or 3 cm, the residual energy is minimum. In order to obtain a therapeutic effect, it is crucial to correctly dose the amount of light. For surface targets, the calculation is relatively simple, but it becomes more complex for deeper targets due to the dispersion and the absorption of the light. The application of high light power can help to reach the deepest tissues, but it also increases the risk of thermal damage to surface tissues. Some techniques try to increase risks associated with the application of high light energy, for example by using high power short pulses and the change in spectral profile of the light beam to distribute it more evenly. However, due to the optical properties of the biological tissues, the transmission of light to significant depth still remains a challenge. Other problems relate to the use of surface high energy laser systems. The lasers used in photobiomodulation often have a spectral beam profile distributed in a Gaussian manner, which means that about 68% of the energy is concentrated in the third centre of the beam. This results in an average irradiation of the area covered by the beam which is 2-4 times smaller than the peak irradiation at the centre of the beam, making the administration of high doses more dangerous, with the risk of overheating the surface tissues. Some techniques, such as optical scanning or the integration of a surface thermal camera with safety functions, may help to reduce the risk of thermal damage. However, given that the residual power of the laser at 2-3 cm deep is very low (0.1-0.01%), there is need for a very high surface dosimetry to obtain an in-depth therapeutic effect. For example, to reach 5 J / cm2 at 2 cm deep, there is need for a surface exposure of 500 J / cm2; to obtain the same effect at 3 cm deep, there are needed 5000 J / cm2. In the visible wavelengths and of the near infrared (NIR), the primary effect in the tissues is the optical dispersion, even if there is a small absorption by transition metals and dense pigmented material, which generates heat. The water in the tissues, which represents more than 55% of the contents thereof, contributes to a significant photothermal response, especially around 970-980 nm. Other components of the tissues such as melanin, keratin and lipids, absorb energy at various wavelengths, further complicating the optical distribution in the tissues. The optical properties of the tissues vary significantly, complicating the achievement of an even clinical goal with photobiomodulation, such as the treatment of deep structures such as the bone. Although there have been developed mathematical models to calculate the penetration depth of the photons, comparative studies show that it is difficult to reach significant depths without invasive methods. Increase in the surface dosimetry may improve the in-depth optical delivery. However, it also increases the risk of overheating the overlying tissues. An approach to resolve these difficulties is to change the spectral profile of the beam by using additional optics to flatten the beam and obtain an even irradiation. However, also with this technique, the optical physical limitations such as attenuation remain, and there is still need to maintain a relatively low irradiation so as to avoid harmful photothermal effects. To summarise, although photobiomodulation has shown a significant therapeutic potential, the effectiveness of its application in greater depths in the human body is still limited by the physical characteristics of the tissues and by the complexity of the optimal dosage. Furthermore, the use of a high-energy electromagnetic radiation entails significant risks of overheating of the surface and subsurface tissues, and although there are methods for mitigating these risks, the clinical challenges in safely reaching deep tissues remain. Therefore, the object of the present invention is to provide an application device for phototherapy that is effective in the treatment of tissues also in-depth, decreasing the risks of trauma to the surrounding tissues. According to the present invention, these and other objects are attained by an application device for phototherapy according to claim 1. Further characteristics of the invention are outlined in the dependent claims. This solution has various advantages with respect to the prior art solutions. Each emitter may actually emit a radiation having an impact surface that is smaller than that of the whole application area of the treatment. This allows to apply a high total energy, even in-depth, reducing the risks related to the use of only one source, like the ones related to overheating surface and immediately sub-surface tissues. While a large single source determines a delivery peak in an area decreasing at the centre of the beam, the superimposed multiple beams in-depth provide an availability of photons to a significantly larger area. In addition, there is observed an optical amplification effect: tests in which there are directly measured the tissues of transilluminated samples show that the optical delivery is significantly greater than that of a comparable single source. This effect is defined as optical dragging and it can be observed with various wavelengths and it is an inherent characteristic of multiple superimposed coherent optical sources. Dragging is an event where two or more oscillators (such as electromagnetic radiations) interact with each other, affecting the frequencies and phases thereof. This interaction may occur through constructive or destructive interference, leading to events such as resonance, where amplitudes are summed besides the sum of the parts. When two or more oscillating systems interact, one or all may be subjected to a change in the frequency so as to be blocked phased, which means that the phase difference between the oscillating systems remains constant over time and resistant to perturbations. The interaction between wavelengths allows to amplify or reduce the amplitude of the wave front, like in the frequency doubling observed in lasers. With laser sources, this event manifests itself as "speckling", with visible light and dark areas. Furthermore, thermal changes in tissues affect the refractive index and the optical transmission, contributing to the speckling effect and creation of localised hot points. The characteristics and advantages of the present invention will be apparent from the following detailed description of a practical embodiment thereof, shown by way of non-limiting example in the attached drawings, wherein: figure 1 schematically shows an application device for phototherapy according to the present invention; figures 2 and 3 show a diagram of two embodiments of the device of figure 1. Referring to the attached figures, with reference numeral 1 there is indicated an application device for phototherapy according to the present invention, which can be used for applying an electromagnetic radiation on a part of the body of a patient. As observable in figure 1, the application device 1 comprises a supporting structure 2; this is preferably part of a handpiece which can be grasped by an operator. The supporting structure 2 comprises a plate-like element 3. The latter has an emission facade 7 preferably having a substantially flat shape, and which in use is faced towards the area of the patient to be treated. Such plate-like element 3 is discshaped. The supporting structure 2 has a plurality of seats 5 for mounting emitters described in the description hereinafter. The seats 5 are obtained on the plate-like element 3. Each seat 5 has a hole in which there is positioned a connector for the emitters. As mentioned above, the application device 1 comprises a plurality of emitters 6 mounted on the supporting structure 2, in particular at the seats 5 described above. Each emitter 6 is configured to receive an electromagnetic radiation from a generator 8 and to emit a beam of this electromagnetic radiation received along a direction of propagation, shown in figure 1 using arrows. Basically, each emitter 6 can be operatively connected to a generator 8 to receive the electromagnetic radiation. Furthermore, each emitter 6 has an emission surface 7 from which there is emitted the beam. The radiation beam is directed along a direction of propagation which is parallel to the normal emission surface 7. Preferably, the generator 8 is part of the application device 1: the generator 8 is therefore operatively connected to each emitter 6. The generator 8 is configured to generate an electromagnetic radiation with wavelength ranging from 300 nm to 11000 nm, preferably between 400 nm and 1700 nm, for the use of the photobiomodulation device. It cannot be ruled out that the generator 8 can generate radiations with different wavelengths for use in other fields. Furthermore, the generator 8 is configured so as to feed each emitter 6 with a different electromagnetic radiation, so as to allow to change the treatment to be carried out on a patient. Furthermore, the generator 8 and the emitters 6 are configured to emit, from each emitter 6, an electromagnetic radiation having an average power comprised between 1 mW and 100 W. The emission may be continuous or pulsed, in the latter case with peak power which may reach up to 10 GW. The generator 8 is a laser generator, LED generator or a combination of laser / LED generator. Preferably, the generator is of the laser type. The generator 8 preferably generates an electromagnetic radiation having a Gaussian or flat hat type beam. The generator 8 and / or the emitters are configured to be controlled by a control unit, described below, by means of control signals generated by the latter. Therefore, the generator 8 and / or the emitters are in signal connection with the control unit. Therefore, the emission mode, that is the intensity of the electromagnetic radiation, the wavelength, the amplitude and the work cycles can be adjusted by means of a control signal. Each emitter 6 further comprises a connection element 9 which is configured to be connected to the generator 8 and to receive and convey the electromagnetic radiation towards the emission surface 7. Preferably, the connection element 9 is an optical fibre. In the shown version, the emission surface 7 is positioned at the end of the optical fibre. However, it cannot be ruled out that the emission surface 7 may be obtained by means of specific optics which allow to direct the beam. The application device 1 comprises a plurality of connectors (not shown in the figures), preferably of the type commonly referred to as “SMA coupling”, which are mounted on the supporting structure 2 at the seats 5 so as to allow the coupling with the optical fibre. In the preferred embodiment, schematically shown in figure 2, the application device 1 comprises a single generator 8 connected to each emitter 6. The connection is carried out by means of an optical unit interposed between the generator 8 and the emitters 6. The optical unit is configured to split the radiation and direct it towards the various emitters 6. Such embodiment allows to reduce the production costs. In another embodiment, shown in figure 3, the application device 1 comprises a plurality of generators 8, each connected to a respective emitter 6. Such version allows to adjust the radiation emitted by each emitter irrespective of the others, this allowing to change the power, the wavelength and emission mode. As observable from figure 1, the emitters 6 are arranged so that the directions of propagation converge towards a point of convergence. Basically, the positioning and the inclination of the emission surfaces 7 allows for the radiation emitted by each to be directed towards the point of convergence. Therefore, each emitter 6 may emit a radiation having an impact surface that is smaller than that of the whole application area of the treatment. Therefore, this allows to apply a high total energy, even in-depth, reducing the risks related to the use of only one source, like the ones related to overheating surface and immediately sub-surface tissues. Each beam impacts in different points the body of the patient, and they are joined to each other in a point of convergence arranged in-depth in the body of the patient. The normals of the emission surface 7, which is parallel to the direction of propagation, are therefore inclined with respect to each other so as to converge. The inclination is such to make the beam meet in a point of convergence arranged distant from the support structure so as to reach a depth of 2-3 cm of the body of the patient. The inclination is considered with respect to a plane, for example the one obtained by the plate-like element 3 and on which the emission surfaces lie. The inclination is by an angle comprised between 1° and 89°, preferably between 20° and 70°. For the determination of the correct angle of inclination, it should be borne in mind that the refraction of light in the passage between two means, area and skin, with a different refractive index (n2 >n1), changes the angle of refraction. The refractive index of the body tissues is comprised in the normal range of 1.34-1.40. This, based on the wavelength, facilitates the forward transmission. As observable from figure 1, the plurality of emitters 6 comprises a series of peripheral 6 emitters. The emission surfaces 7 of these emitters 6 are arranged substantially aligned along a circumference. Preferably, such emission surfaces 7 substantially lie on the same plane. However, it cannot be ruled out that they can be staggered on multiple planes. The device 1 preferably comprises from 5 to 15 peripheral emitters, preferably 6 or 7. The emission surfaces 7 are inclined towards the centre of the circumference. That is, the normal of the emission surfaces 7, and therefore the direction of propagation, is faced towards a straight line normal to the circumference and passing through the centre. Therefore, the radiations emitted form a cone whose vertex is the point of convergence. Usefully, the normals of the emission surface 7 are inclined by the same angle with respect to a plane parallel to the circumference. The plurality of emitters 6 also comprises a central emitter 6 whose emission surface 7 emits a beam with direction of propagation parallel to the normal straight line mentioned above. The emission surface 7 of such central emitter 6 is arranged at the centre of those of the peripheral emitters. All beams of the peripheral emitters therefore meet with the beam of the central emitter. The central emitter 6 may be connected to the same generator of the peripheral emitters, or alternatively to a different generator, laser generator and / or LED generator. The beam emitted by the central emitters is of the Gaussian of flat hat type. However, it cannot be ruled out that such beam may be of another type. In order to obtain such arrangement, a plurality of seats 5 on which the emitters are mounted there is arranged aligned along the circumference; at least one seat 5 instead is arranged at the centre of such circumference. Suitably, the application device 1 comprises regulation means 10 interposed between the supporting structure 2 and the emitters 6. The regulation means 10 are configured to act on the emitters so as to change the distance between the point of convergence and the supporting structure 2, therefore allowing to change the depth at which the application device 1 acts. In order to carry out such adjustment, the regulation means 10 comprise a variation unit operatively connected to the peripheral emitters and configured to change the inclination of such emitters and / or the distance between the emitters 6 so as to change the distance between the point of convergence and the supporting structure 2. Preferably, the variation unit is configured to change both the inclination and the distance between the peripheral emitters 6. As observable below, the variation unit may act through various assembly seats which change the status of the emitters and / or through a movable assembly of the emitters on the supporting structure 2 (translational and rotational) and the presence of actuators which move the emitters. The point of convergence can be moved away or approached respectively by increasing or reducing the distance between the emitters 6, therefore basically the diameter of the circumference. The point of convergence can also be approached or moved away by increasing or reducing the inclination angle. In an embodiment, the variation unit of the regulation means 10 provides for the presence of a first series of seats 5 aligned on a first circumference and a second series of seats 5 aligned on a second circumference having a diameter smaller than the first circumference. Basically, the two series of seats 5 are aligned on two concentric rings. In a version of such embodiment, the inclination of the emitters 6 on the first series of seats 5 is the same as on the second series of seats 5. In another version, the inclination of the emitters 6 arranged in the first series of seats 5 is different from that of the emitters 6 arranged in the second series of seats 5. The choice of the inclination and of the radius of the two rings allows to change the depth of the point of convergence emitted by the first series with respect to the one emitted by the second series. This allows to move the emitters from one seat to the other to change the depth of the point of convergence. Alternatively, there may be provided emitters 6 arranged both in the first and in the second series of seats, and activate them optionally depending on the desired depth. In a version, the variation unit of the regulation means 10 comprise a movement element connected to the peripheral emitters and configured to approach them / move them away with respect to each other displacing them between the two series of seats 5. Such movement element for example comprises one or more guides on which there are mounted the peripheral emitters slidably. Furthermore, the movement element comprises an actuator configured to move the peripheral emitters along the guide. In a version, there are present a plurality of series of seats. Preferably, the first series of seats 5 is obtained on a first portion of the plate-like element 3, while the second series of seats 5 on a second portion of the plate-like element 3, arranged concentric to the first portion, as observable in figure 1. According to another embodiment, which could also be integrated with the preceding embodiment, the variation unit of the regulation means 10 comprise rotation means configured so as to rotate the emission surface 7 so as to vary the inclination of the emitted radiation. Basically, the emission surfaces 7 are rotatably fixed to the supporting structure 2. Then, there is present an actuator operatively connected to the emission surfaces 7 to rotate them. The rotation could also be carried out manually. The variation unit is also configured to move the peripheral emitters approaching to / moving away from the body of the patient, that is along a direction perpendicular to the supporting structure 2. Such movement is carried out by means of the sliding guides and actuators. The regulation means 10 are also configured to adjust the amplitude of the area of impact of the emitted light radiation of the central emitter. In order to carry out such adjustment, the regulation means 10 comprise a modification unit operatively connected to the central emitter 6 and configured to increase / decrease the area of impact of the light radiation. In an embodiment, the modification unit comprises an optical system associated with the central emitter capable of increasing / decreasing the amplitude of the emitted beam, for example through optics arranged at the central emitter 6 by means of an actuator changes the characteristics thereof to spread the emitted beam with various amplitudes. In an embodiment, which can be integrated with the one described above, the modification unit comprises a movement means operatively connected to the central emitter and configured to move it to approach / move away from the supporting structure 2 (along a direction parallel to the normal straight line mentioned above) to approach it to / move it away from the body of the patient. Such movement means for example comprises a guide on which it is mounted the central emitter and an actuator which moves it along the guide. The application device 1 also comprises a control unit which is operatively connected to the various components to control the operation thereof. The control unit comprises processing means, such as for example a microprocessor, which are configured to generate control signals to be sent to the components of the device 1 to control the operation thereof. The control unit also comprises an interfacing system, such as for example a graphic interface, through which an operator can set the adjustable values and set parameters used for delivering the treatment. The interfacing system is configured to receive the value of one or more parameters and generate a corresponding parameter signal to be sent to the processing means. In particular, the interfacing system is configured to receive one or more of the following parameters: anatomical district, disease to be treated, characteristics of the tissue to be treated, desired therapeutic effect, and depth and extension of a lesion to be treated (for example identified by using an ultrasound scanner). This allows to generate, depending on the parameters received, a corresponding parameter signal, preferably of the electric type, which is sent to the processing means. The processing means, preferably through a specific software installed on the microprocessor, are configured to receive the parameter signal, to process it and to generate a control signal as a function of the processing carried out. The control signal is sent to the various components, and in particular to the generator 8, to the emitters 6 and to the regulation means 10 to carry out the following adjustments: - adjusting the amplitude of the area of impact of the electromagnetic radiation emitted by the central emitter; - adjusting the position of the point of convergence of the emitted radiations (changing the inclination and / or the position of the emitters 6); - adjusting the average and peak power of the emitters so as to transmit the correct therapeutic dose in-depth depending on the selected effect; - varying the emission mode of the emitters as a function of the type of tissues and of the selected effect; - varying the wavelength of the electromagnetic radiation emitted by one or more of the emitters so as to appropriately interact with the chromophores of the treated biological tissue and deliver the correct therapeutic dose to the tissue target in-depth to obtain the selected effect. The operation of the invention seems clear to the person skilled in the art given that it has been described and in particular it is as follows: the application device 1 is positioned at the area to be treated of a patient, directing the emitters 6 towards such area; there is then activated the generator which provides radiation to the emitters; they emit the radiation, directing it towards the point of convergence; such point of convergence, depending on the treatment, is found at a determined depth in the body of the patient. Before applying the electromagnetic radiation, the operator may insert through the interfacing system the information on the physical characteristics of the tissues of the patient, the anatomical district, the disease, the desired effect (bio-stimulant, analgesic, antiedemic, relaxant and anti-inflammatory agent) and the depth and extension of the lesion and / or disease to be treated. The processing means process the information entered by the operator and control the emitters so as to converge a specific electromagnetic radiation towards the desired point of convergence. The processing means also define the wavelengths of the electromagnetic radiations, the average and peak power, the emission mode and the dose so as to deliver the correct amount of energy to the set depth so as to obtain the selected therapeutic effect. The system thus conceived is susceptible to numerous modifications and variants, all falling within the inventive concept; furthermore, all details can be replaced by technically equivalent elements.

Claims

1. Application device (1) for phototherapy comprising a supporting structure (2) and a plurality of emitters (6) mounted on said supporting structure (2), each emitter (6) being configured to receive an electromagnetic radiation from a generator and to emit a beam of said electromagnetic radiation along a direction of propagation; wherein said emitters (6) are arranged so that said directions of propagation converge towards a point of convergence;wherein each of said emitters (6) comprises an emission surface (7) from which said beam is emitted, said plurality of emitters (6) comprises a series of peripheral emitters (6) whose said emission surfaces (7) are arranged substantially aligned along a circumference; and a central emitter (6) whose emission surface (7) emits a beam with propagation direction parallel to a straight line normal to said circumference.

2. The application device (1) in accordance with claim 1, characterised in that the normals of said emission surfaces (7) of said peripheral emitters (6) are inclined by a same angle relative to a plane parallel to said circumference.

3. The application device (1) in accordance with one of the preceding claims, characterised in that it comprisesregulation means (10) interposed between said supporting structure (2) and said emitters (6), said regulation means (10) being configured to act on said emitters so as to vary the distance between said point of convergence and said supporting structure.

4. The application device (1) in accordance with one of the preceding claims, characterised in that it comprises at least one generator (8) operatively connected to said emitters (6), said generator (8) being configured to generate a radiation with wavelength ranging from 300 nm to 11000 nm.

5. The application device (1) in accordance with the preceding claim, characterised in that said generator (8) is a laser generator, LED generator or combined laser / LED combination generator.

6. The application device (1) in accordance with one of the preceding claims, characterised in that it comprises a single generator (8) operatively connected to each of said emitters (6) to supply them with said electromagnetic radiation.

7. The application device (1) in accordance with one of claims 1 to 5, characterised in that it comprises a plurality of generators (8), each of which is connected to a respective emitter (6).

8. The application device (1) in accordance with one ofthe preceding claims, characterised in that it comprises a control unit operatively connected to said generator (8) to control its operation.

9. The application device (1) in accordance with preceding claim, characterised in that said control unit comprises an interfacing system configured to receive one or more of the following parameters: anatomical district, pathology to be treated, characteristics of the tissue to be treated, desired therapeutic effect, and depth and extension of a lesion to be treated; said interfacing system being configured to generate a corresponding parameter signal.

10. Application device (1) according to the preceding claim, characterized in that said control unit comprises processing means in signal connection with said interfacing system and configured to receive said parameter signal, to process it, and to generate a control signal suitable for controlling the operation of said device (1) so as to perform the following operations:- adjusting the amplitude of the impact area of the electromagnetic radiation emitted by said central emitter;- adjusting the position of said convergence point;- adjusting the average and peak power of said emitters;- varying the emission mode of said emitters as afunction of the type of tissues and of the selected effect;- varying the wavelength of the electromagnetic radiation emitted by one or more of said emitters.A

Images