Scanning electromagnet

Abstract

Scanning electromagnet, configured to deflect and / or direct a beam of electrically charged particles, comprising at least one yoke (2), made of ferromagnetic material and comprising at least a first pair of inner walls (4) and at least a second pair of inner walls (5) which define between them at least one channel (3) extending along a development axis Z; at least a first electric coil (8), configured to generate a first magnetic field parallel to a first axis X; at least a second electric coil (9), configured to generate a second magnetic field, parallel to a second axis Y, transversely with respect to said development axis Z; said yoke (2) comprises first housing seats (10) made on said first pair of inner walls (4) and second housing seats (11) made on said second pair of inner walls (5); said first coil (8) being at least partially housed in said first housing seats (10) in such a way as to generate said first magnetic field in said channel (3) parallel to said first axis X; said second coil (9) being at least partially housed in said second housing seats (11) in such a way as to generate said second magnetic field in said channel (3), parallel to said second axis Y.

Description

SCANNING ELECTROMAGNETDESCRIPTIONField of application of the invention

[0001] The present invention relates to a scanning electromagnet, according to the preamble of independent claim no. 1.

[0002] The present invention is used in the technical field of the production and marketing of electrical devices and in particular in the production of magnets and electromagnets.

[0003] In particular, the scanning electromagnet according to the invention is intended to be advantageously used to guide a beam of accelerated charged particles, for example, for the treatment of tumours in cancer patients using hadrontherapy.

[0004] Therefore, the scanning electromagnet according to the invention is advantageously used in the technical field of the production and marketing of apparatus, devices, and / or accessories for particle acceleration systems, for example for hadrontherapy, ion implantation, or the like.State of the art

[0005] For the sake of simplicity, hereinafter we will refer to the specific application of hadrontherapy. Obviously, the electromagnet here disclosed could easily be used in other technical applications without departing from the scope of protection of this patent application. For example, the electromagnet here disclosed could be used in ion implantation processes in the surface treatment of materials, such as in the production of semiconductor devices.

[0006] Hadrontherapy is an advanced form of radiotherapy that uses beams of charged particles, such as protons or heavy ions (usually carbon), to treat tumours in cancer patients.

[0007] Unlike conventional radiotherapy (which uses X-rays or photons), hadrontherapy exploits the physical properties of charged particles to target the tumour with great precision, minimizing damage to surrounding healthy tissue.

[0008] Hadrontherapy initially involves a particle beam production phase, in which particles (such as protons or carbon ions) are generated and then accelerated in a particle accelerator, such as a synchrotron or cyclotron. These devices accelerate the particles to very high speeds (on the order of a fraction of the speed of light) to increase their energy.

[0009] Hadrontherapy then involves a particle energy modulation phase, in which theenergy is adjusted to penetrate the body only to a desired depth, i.e., the exact depth of the tumour.

[0010] Starting from the type of charged particle used and the depth the particles must reach within the patient's body to hit the tumour, the energy the particles must reach is chosen based on their Bragg peak.

[0011] In this way, the protons and / or carbon ions release most of their energy at the final point of their trajectory, allowing the radiation dose to be concentrated primarily on the tumor, avoiding the risk of damaging surrounding tissue.

[0012] Finally, hadrontherapy involves a phase in which the charged particle beam is administered to the patient, at the tumour site. More specifically, once the particles reach the desired energy, they are directed toward the patient via a magnetic guidance system. The beam is modulated and controlled to ensure it hits the tumour with the necessary precision.

[0013] The scanning magnet (or electromagnet) is a fundamental element in the final phase of the hadrontherapy process: the beam administration phase.

[0014] Indeed, the primary purpose of the scanning electromagnet is to precisely move and direct the particle beam to cover the entire tumour area, without physically moving the patient or the accelerator.

[0015] The accompanying figure 1 shows an example of a beam guidance system 100, in which, after the particles have been accelerated and reached the required energy, they are directed along a transfer path 101 that carries the beam 102 from the accelerator to the patient.

[0016] In more detail, the attached Figure 1 shows a schematic of the operation of a "gantry," i.e., an optical system designed to convey a beam of charged particles for use in hadrontherapy. Specifically, the scanning magnet used in the system shown in Figure 1 is of the downstream type, i.e., placed downstream of a curvature magnet 103 (also known in the technical jargon of the sector as a "bending magnet" or "dipolar magnet" or "dipole").

[0017] Normally, in this phase, quadrupolar magnets are used to focus the beam, and dipolar magnets to change its direction.

[0018] The beam is then directed into a treatment room, where the patient to be treated is located.

[0019] Typically, scanning magnets (or electromagnets) are arranged at an exit section of the particle beam 102, close said treatment chamber.

[0020] Currently, the most commonly used scanning magnets are of the "separatefunction" type, i.e., they comprise a first magnet to vary the position of the beam along the X-axis and a second magnet, arranged in series with the first magnet along the transfer path 101 , to vary the position of the beam along the Y-axis.

[0021] These known scanning magnets generate two distinct, orthogonal magnetic fields that deflect the beam along the two axes (X and Y), allowing the beam to "scan" the tumor area, i.e., to intercept the entire tumour area to be treated in a controlled manner.

[0022] Typically, the movement of the beam through the scanning magnets is synchronized with the adjustment of the beam energy itself. This ensures that the radiation is delivered at the correct depth at each point, guaranteeing optimal three- dimensional distribution of the radiation emitted by the particle beam in the tumour.

[0023] The use of scanning magnets in hadrontherapy allows for greater precision, as the beam can be directed with extreme precision, reducing exposure to healthy tissue and limiting side effects.

[0024] Therefore, hadrontherapy is particularly effective for treating tumours located near critical structures or in regions difficult to reach with traditional surgery or conventional radiotherapy. Furthermore, the ability to shape the beam in 3D reduces damage to surrounding tissue, improving clinical outcomes.

[0025] Therefore, scanning magnets play a critical role in the precise distribution of the energy carried by the charged particles to the tumour. Positioned along the beam transfer path, these magnets control the direction of the beam to ensure it hits the exact desired area. Their action allows for highly targeted and effective treatment, minimizing side effects compared to traditional therapies.

[0026] However, the scanning magnets of the known type briefly described so far have proved to be not free from drawbacks in practice.

[0027] The main drawback is that known magnets have significant limitations in their ability to treat large tumours or tumours with complex geometries. In fact, the treatment area that known magnets allow to obtain is very limited, especially when they are placed close to the patient, as in the case of downstream magnets.

[0028] Split-function scanning magnets are used in hadrontherapy to guide proton or ion beams on specific trajectories, ensuring extremely precise dose distribution. In this type of system, two or more magnets are responsible for separating the horizontal scanning (X-axis) and vertical scanning (Y-axis) functions, rather than entrusting both directions to a single magnet. This approach offers some advantages in terms of control and precision but also presents some specific disadvantages.

[0029] As is known, split-function scanning magnets are mostly used for applicationswhere their distance from the patient is not negligible, i.e. normally around 6-8 m. In fact, when the scanning magnet is so far away from the patient (or more generally from the area to be treated) it is possible to produce essentially two identical magnets, arranged rotated 90° from each other, for scanning in X and Y.

[0030] A known type of split-function scanning magnet produced in this way has proven to be slightly inefficient in practice; however, it allows for savings in manufacturing and / or maintenance and / or component costs.

[0031] Furthermore, if the system requires the installation of additional magnets downstream of the scanning magnet, these additional magnets (a configuration known in technical jargon as "last dipole upstream scanning") are very large and heavy and therefore complex and expensive to design and manufacture.

[0032] In this situation, to reduce the size and production costs of the entire system, it is preferable to position the scanning magnets as the last element before the patient, at a distance of approximately 2-3 m from the patient.

[0033] However, to maintain the same scanning area (i.e., to be able to move the charged particle beam over a predetermined target area, usually a square of at least 20 cm on each side), the smaller the distance from the target area (e.g., the patient), the greater the deflection angle that the scanning magnets must be able to impart to the charged particle beam.

[0034] Therefore, in this situation, scanning magnets become significantly more complex and expensive.

[0035] To overcome the aforementioned drawbacks, scanning magnets are known, one for the deflection along the axis X and one for the deflection along the axis Y, designed to be constructively different, in which the magnet of the upstream pair is relatively simple, while the magnet of the downstream pair (i.e., closer to the patient) is increasingly complex.

[0036] However, even this prediction has proven to be not free from drawbacks in practice.

[0037] The main drawback is that, being different, the two scanning magnets require different design and manufacturing, consequently increasing design and manufacturing costs.

[0038] Furthermore, each scanning magnet requires a corresponding power supply, with the power supply for the downstream magnet being extremely expensive and complex, as it must be able to guarantee high voltages and variable currents.

[0039] It is therefore clear that the relevant technical sector needs to optimize and / orsacrifice certain features to limit manufacturing costs. In particular, a system with magnets with separate functions requires a greater number of components (more magnets, control systems, and synchronization mechanisms). This increases construction complexity, increases the need for maintenance, and increases production and operating costs.

[0040] The management and synchronization between the two magnets to ensure that the beam of charged particles is correctly directed with respect to both the X and Y axes requires an extremely costly and complex power supply and control infrastructure.

[0041] A further drawback lies in the fact that the presence of two distinct magnets requires a larger space for the installation of the scanning magnets themselves. This can represent a challenge in terms of designing the clinical infrastructure, as it requires larger treatment rooms or complex structural adaptations.

[0042] A further drawback lies in the fact that the weight of the system is also considerable, requiring adequate supports and reinforced structures for mounting the magnets.

[0043] A further drawback lies in the fact that the presence of two distinct magnets and the complexity of the system lead to an increase in construction, installation and maintenance costs. The magnets used for scanning in hadrontherapy are already expensive due to their precision and the necessary materials, and the subdivision of functions requires an even greater investment.

[0044] Furthermore, the subdivision of functions can lead to slightly longer scanning times compared to simpler systems. This may be due to the need to precisely coordinate the movements of the beam along the two axes, slightly delaying the delivery of the dose to the patient.

[0045] Asynchronous movements between the magnets for horizontal and vertical scanning can lead to a slight inefficiency in the distribution of the particle beam, lengthening the duration of the treatment session.

[0046] Known-type scanning magnets have limits in the response speed or in the synchronized precision between the two axes, reducing the effectiveness in some clinical situations, such as in moving tumours (for example those related to breathing).

[0047] Furthermore, known-type scanning magnets require a large supply of energy to function correctly, increasing operating costs, but may require more robust electrical systems and more powerful cooling systems to manage the heat generated by the magnets themselves.

[0048] In summary, while separate known-type magnets offer several advantages interms of precision of beam control, their complexity, costs and potential technical problems represent significant drawbacks for adoption and large-scale implementation in the clinical setting.

[0049] An example of a known-type scanning magnet is described in document US 2022 / 181042 A1. However, the magnet described therein has proven in practice not to be without drawbacks.

[0050] The main drawback lies in the fact that the magnet described in this document is extremely complex and expensive to produce. Furthermore, the magnet described therein uses a set of out-of-phase voltages to be able to function and must be constantly actively controlled.

[0051] Furthermore, the magnet described therein is based on a circular geometry and necessarily requires that the channel configured to be crossed by said particle beam has a circular cross-section.

[0052] This provision is disadvantageous, as will become clear in the continuation of the description.Presentation of the invention

[0053] The present invention intends to overcome the technical drawbacks mentioned above by providing a scanning electromagnet capable of overcoming the drawbacks of the known art mentioned above.

[0054] In particular, the main object of the present invention is to provide a scanning electromagnet that is structurally and functionally completely reliable.

[0055] A further object of the present invention is to provide a scanning electromagnet that is efficient from an energy point of view, i.e. that requires less electrical energy to function compared to known-art scanning magnets.

[0056] Another object of the present invention is to provide a scanning electromagnet that can act on a larger area compared to known-art scanning magnets.

[0057] A further object of the present invention is to provide a scanning electromagnet that is capable of guaranteeing, with great precision, the variation of the position and / or inclination of the particle beam.

[0058] Another object of the present invention is to provide a scanning electromagnet that requires simpler and more economical power supply apparatuses compared to the known art.

[0059] A further object of the present invention is to create a scanning magnet that can be installed "downstream", i.e. as the last element before the target area, containing the manufacturing costs of both the magnet and its electrical power supply.

[0060] Still, not the last object of the present invention is to provide a scanning electromagnet that is industrially applicable in any particle accelerator.

[0061] Another object of the present invention is to provide a scanning electromagnet that can easily replace one or more scanning magnets of a plant already in use.

[0062] A further object of the present invention is to provide a scanning electromagnet that can minimize the number of power supplies and different supply currents necessary for the operation of the electromagnet itself.

[0063] Another object of the present invention is to provide a scanning electromagnet that can function with a channel for the passage of the particle beam that is either quadrangular or otherwise polygonal.

[0064] Another object of the invention is to provide an electromagnet that is configured to operate at high electrical powers and high energies of the particle beam. In particular, an object of the invention is to provide a scanning electromagnet suitable for use in particle accelerators for hadronic therapy (or hadrontherapy), in particular for oncological treatments.

[0065] Another object of the present invention is to provide a scanning electromagnet that has alternative characteristics with respect to the known art.

[0066] These objects, together with others that will be better clarified below, are achieved by a scanning electromagnet of the type according to claim 1.

[0067] These objects, together with others that will be better clarified below, are achieved by a scanning electromagnet of the type according to the dependent claims. Brief description of the drawings

[0068] The advantages and characteristics of the present invention will emerge clearly from the following detailed description of some preferred but not limiting configurations of a scanning electromagnet with particular reference to the following drawings:- figure 1 shows a schematic view of a guidance system for a beam of charged particles which ends with an example of a scanning electromagnet according to the present invention;- figure 2 shows an axonometric view of a scanning electromagnet object of the present invention;- figure 3 shows a plan view of the scanning electromagnet according to the invention illustrated in figure 2;- figure 4 shows a front view of the scanning electromagnet according to the invention illustrated in figures 2 and 3;- figure 5A shows a front view of the electromagnet according to the invention, in across-section taken along the line V-V of figure 2;- figure 5B shows an enlarged detail of the front view illustrated in figure 5A;- figure 5C shows an enlarged detail of figure 5B, identified by the line C;- figure 6 shows an axonometric view of the electromagnet of figure 2, with some parts removed to better highlight others;- figure 7 shows an axonometric view of the electromagnet according to the invention, in a second embodiment, with some parts removed to better highlight others;- figure 8 shows a top plan view of the electromagnet illustrated in figure 7 in its second embodiment;- figure 9 shows a cross-sectional view of the electromagnet according to the invention in its third embodiment;- figure 10 shows a cross-sectional view of the electromagnet according to the invention in accordance with its fourth embodiment;- figure 11 shows a cross-sectional view of the electromagnet according to the invention in accordance with its fifth embodiment;- figure 12 shows a cross-sectional view of the electromagnet according to the invention in accordance with its sixth embodiment.Detailed description of the invention

[0069] The present invention has as its object a scanning electromagnet, which has been indicated in the attached figures with the reference number 1.

[0070] The scanning electromagnet in question may be advantageously employed to deviate, direct and / or control a beam of electrically charged accelerated particles.

[0071] The main (but not limiting) application example of the electromagnet according to the invention is that of hadrontherapy, in which the electromagnet in question is configured to deviate a beam of charged particles (normally protons or carbon ions) to treat tumours in oncological patients.

[0072] Advantageously, in accordance with the example illustrated in the attached figure 1 , the scanning electromagnet 1 object of the present invention is intended to be placed downstream of a transfer path 101 of a guidance system 100 of a beam of charged particles 102.

[0073] The scanning electromagnet according to the invention is configured to direct the beam of charged particles in a precise and controlled manner within a work area.

[0074] Preferably, the work area of the electromagnet in question has a polygonal shape, in particular quadrangular.

[0075] The scanning electromagnet 1 according to the invention is configured to deflectand / or direct a beam of electrically charged particles.

[0076] The electromagnet 1 comprises at least one yoke 2, made of ferromagnetic material and configured to concatenate a magnetic field flux.

[0077] The yoke 2 is preferably a magnetic yoke and is configured to guide a magnetic flux generated by an electric current (as described in detail below) through a defined path.

[0078] Advantageously, the yoke 2 is configured to guide the magnetic flux, reducing dispersion and optimizing the efficiency of the electromagnet.

[0079] Preferably, the yoke 2 defines a magnetic circuit.

[0080] Preferably, the yoke 2 is made of ferromagnetic material, for example soft iron or laminated steel, preferably in such a way as to offer low resistance to the passage of magnetic flux.

[0081] In other words, the yoke 2 is preferably constructed with materials that have a high magnetic permeability, such as iron, steel or special alloys, to channel the magnetic flux and reduce losses.

[0082] Preferably, the yoke 2 has low magnetic reluctance to allow for an efficient passage of the magnetic flux.

[0083] Preferably, the yoke 2 has a closed core shape, for example a frame or toroid shape, to reduce the dispersion of the magnetic flux to the outside.

[0084] In this way, the yoke 2 prevents the magnetic flux from escaping the desired path, keeping it confined within the magnetic circuit and thus improving the efficiency of the system.

[0085] The yoke 2 comprises at least a first pair of opposing inner walls 4 and at least a second pair of opposing inner walls 5. Preferably, the walls 4, 5 are substantially planar.

[0086] The first pair of inner walls 4 comprises, preferably, at least a first inner wall 4' and a second inner wall 4", opposite each other.

[0087] Similarly, the second pair of inner walls 5 comprises, preferably, at least a third inner wall 5' and a fourth inner wall 5", opposite each other.

[0088] Preferably, with particular reference to the attached figure 5B, the third wall 5' mechanically connects a first end edge 41 of the first wall 4' with a corresponding second end edge 42 of the second wall 4". Similarly, preferably, the fourth wall 5" mechanically connects a third end edge 43 of the first wall 4' with a corresponding fourth end edge 44 of the second wall 4".

[0089] In other words, preferably, the first inner wall 4' is parallel to the second inner wall 4". Furthermore, preferably, the third inner wall 5' is parallel to the fourth inner wall 5".

[0090] Preferably, the first and second inner walls 4', 4" of the first pair of inner walls 4 are orthogonal with respect to the third and fourth inner walls 5', 5" of the second pair of inner walls 5.

[0091] Conveniently, the inner walls 4, 5 define between them at least one channel 3 configured to be crossed by said particle beam.

[0092] The channel 3 extends along a development axis Z between an inlet section 6 and an outlet section 7.

[0093] The scanning electromagnet 1 also comprises at least a first electric coil 8, mechanically and magnetically coupled to said yoke 2, configured to generate a first magnetic field, at least in said channel 3, directed parallel to a first axis X, transversely with respect to said development axis Z.

[0094] The electromagnet 1 according to the invention also comprises at least a second electric coil 9, mechanically and magnetically coupled to said yoke 2, configured to generate a second magnetic field, at least in said channel 3, directed parallel to a second axis Y, different from said first axis X, transversely with respect to said development axis Z.

[0095] Preferably, each electric coil 8, 9 comprises a plurality of electrical conductors (or sub-coils), preferably connected in series with each other. Preferably, each electrical conductor comprises one or more electrically conductive wires wound in such a way as to give the electrical conductor the desired shape, for example substantially an annular shape. The coils 8, 9 are preferably supplied electrically in a separate manner.

[0096] For example, each conductive wire of the first and / or second coil 8, 9 can be made of copper or aluminium or other conductive metals.

[0097] In accordance with a different embodiment, the first and / or second coil 8, 9 can be made with superconducting materials, such as for example niobium-titanium (Nb-Ti) or niobium-tin (Nb3Sn) cooled to very low temperatures to lower (and almost nullify) their electrical resistance.

[0098] Furthermore, the first and / or second coil 8, 9 can be made with high-temperature superconducting materials, such as for example ReBCO and BSCCO.

[0099] Preferably, the coil comprises at least one insulating layer configured to wrap and / or cover the plurality of wires, to prevent short circuits between the turns of the coil.

[0100] For example, the insulating layer can be made of resin or plastic or rubber or the like.

[0101] According to the invention, the yoke 2 comprises a first group 10 of housing seats made on said first pair of inner walls 4 and a second group 11 of housing seatsmade on said second pair of inner walls 5.

[0102] According to the invention, said first coil 8 is at least partially housed in said first group 10 of housing seats in such a way as to generate said first magnetic field in said channel 3 parallel to said first axis X.

[0103] Conveniently, said second coil 9 is at least partially housed in said second group 11 of housing seats in such a way as to generate said second magnetic field in said channel 3, parallel to said second axis Y.

[0104] In this way, the electromagnet 1 according to the invention allows for improving the electrical performance compared to known-type magnets.

[0105] Advantageously, in accordance with the preferential embodiment of the present invention illustrated in the attached figures, said channel 3 has a substantially quadrangular shape.

[0106] Preferably, said first pair of inner walls 4 and said second pair of inner walls 5 define the four sides of said channel 3 having a substantially quadrangular shape.

[0107] In this way, each coil 8, 9 is able to generate a corresponding magnetic field placed across the channel 3, wherein the first coil 8 generates a first magnetic field transverse to the first pair 4 of inner walls and wherein the second coil 9 generates a second magnetic field transverse to the second pair 5 of inner walls.

[0108] In this way, preferably, for the same footprint (i.e. average diameter) of a channel 3 of circular shape, a channel 3 of square shape defines a larger treatment area, in particular greater of about 27%.

[0109] Furthermore, for the treatment of tumours, where the shape is often irregular and / or not inscribable within a single treatment area, the juxtaposition of square areas is easier and more immediate than round areas, which necessarily imply untreated intermediate areas (and therefore too low a treatment) or an overlap of the areas, leading to too high treatment concentrations.

[0110] Advantageously, each said housing seat of said first group 10 extends between an opening 14 made on said first pair of inner walls (4) and an opposite bottom wall 15.

[0111] Preferably, in the same way, each said housing seat of said second group 11 extends between a corresponding opening 14 made on said second pair of inner walls 5 and an opposite bottom wall 15.

[0112] Each seat of the first and second group of housing seats 10, 11 comprises two side walls 16, parallel to each other and transverse with respect to the opening 14 and the bottom wall 15 and placed to connect the latter

[0113] Preferably, the extension of the side walls 16 is greater than the extension ofthe bottom wall 15 and / or the opening 14.

[0114] In other words, the depth of each housing seat is preferably greater than its width.

[0115] Even more preferably, the linear depth of each housing seat is at least ten times its linear width.

[0116] In accordance with various embodiments not illustrated in the attached figures, each housing seat can have any shape, for example (in the case where the conductors are made with superconducting material) substantially square which, preferably, houses corresponding conductors with a substantially square cross-section.

[0117] Advantageously, said first electric coil 8 and / or said second electric coil 9 comprises at least one outer wall 12 facing said channel 3.

[0118] Preferably, the outer wall 12 of the electric coil 8 is provided at the opening 14 of the corresponding housing seat.

[0119] Preferably, said first pair of inner walls 4 comprises at least a first inner wall 4', which is provided with a plurality of first seats 10' of said first group 10 arranged side by side.

[0120] Preferably, said first electric coil 8 comprises a plurality of first electrical conductors 17 housed each in a corresponding said first seat 10' of said first group 10 of housing seats.

[0121] Advantageously, said second pair of inner walls 5 can comprise at least a third inner wall 5', which is provided with a plurality of third seats 1 T of said second group 11 arranged side by side.

[0122] Preferably, said second electrical coil 9 comprises a plurality of second electrical conductors 18 housed each in a corresponding said third seat 1 T of said second group of housing seats 11.

[0123] Preferably, the first coil 8 has a substantially annular shape and said first conductors 17 comprise a forward path, housed in the first seats of housing 10' of the first inner wall 4', and a return path, housed in the second seats of housing 10" of the second inner wall 4".

[0124] Similarly, preferably, the second coil 9 has a substantially annular shape and said second conductors 18 comprise a corresponding a forward path, housed in the third seats of housing 1 T of the third inner wall 5', and a return path, housed in the fourth seats of housing 11" of the fourth inner wall 5".

[0125] Preferably, in accordance with the embodiment illustrated in the attached figure 6, the first coil 8 and the second coil 9 comprise a curved connecting portion 19 betweenthe forward path and the return path.

[0126] Advantageously, each first and / or second electrical conductor 17, 18 of the first coil 8 and / or the second coil 9 comprises a corresponding curved connecting portion 19 between the forward path and the return path.

[0127] Preferably, the curved portion 19 has an arcuate shape and preferably develops on a plane transverse to the development axis Z, in particular it develops on a plane parallel to the plane defined by the axis X and the axis Y.

[0128] Therefore, the curved portion 19 of the first coil 8 and / or the second coil 9 preferably defines a portal 20 capable of being crossed by the conductors of the other coil 9, 8.

[0129] In accordance with the preferential embodiment of the present invention, the curved portion 19 of the second coil 9 defines a portal 20 crossed at least partially by the first coil 8.

[0130] In more detail, the first coil 8 has a linear length (along the development axis Z) greater than the linear length of the second coil 9.

[0131] In this way, preferably, the first electrical conductors 17 of the first coil are placed to cross the portal 20 defined by the curved portion 19 of the second conductors 18 of the second coil 9.

[0132] Preferably, the curved portion 19 of the first coil 8 is arranged frontally alongside the curved portion 19 of the second coil 9.

[0133] In accordance with a further embodiment not illustrated in the attached figures, the first coil 8 has a linear length (along the development axis Z) substantially equal to the linear length of the second coil 9.

[0134] In this way, preferably, the first electrical conductors 17 of the first coil 8 are placed to cross the portal 20 defined by the curved portion 19 of the second conductors 18 of the second coil 9, at only one of the two ends.

[0135] In this way, in both embodiments, the electromagnet 1 according to the invention is compact.

[0136] Advantageously, said yoke 2 made of ferromagnetic material comprises a plurality of teeth 13, configured to guide said magnetic field, so that the field lines of said magnetic field cross said channel 3 remaining parallel to each other.

[0137] Preferably, each tooth 13 remains defined between two adjacent housing seats.

[0138] Each inner wall 4', 4", 5', 5" comprises a plurality of respective teeth 13, which remain defined between the corresponding housing seats of the first and second group 10, 11.

[0139] Preferably, the first magnetic field generated by the first coil 8 intercepts and flows in the teeth 13 of the first pair of walls 4', 4", which remain defined between the housing seats of the first group 10.

[0140] Preferably, the second magnetic field generated by the second coil 9 intercepts and flows in the teeth 13 of the second pair of walls 5', 5", which remain defined between the housing seats of the second group 11.

[0141] Advantageously, as anticipated above, said inner walls 4', 4" of said first pair of inner walls 4 are parallel to each other.

[0142] Advantageously, in the same way, said inner walls 5', 5" of said second pair of inner walls 5 are parallel to each other and transverse with respect to said inner walls 4', 4" of said first pair of inner walls 4.

[0143] Preferably, the first inner walls 4', 4" have a substantially equal planar extension and, preferably, also the second inner walls 5', 5" have a substantially equal planar extension between them.

[0144] In accordance with the preferential embodiment of the present invention, the planar extension of the first inner walls 4', 4" is equal to the planar extension of the second inner walls 5', 5". In this way, preferably, the channel 3 has a substantially square shape.

[0145] Advantageously, in accordance with the particular embodiment of the present invention illustrated in the attached figures 7 and 8, said channel 3 is provided with a minimum width at said inlet section 6, and a maximum width at said outlet section 7.

[0146] Preferably, said width of said channel 3 increases, for example linearly, along said development axis Z between said inlet section 6 and said outlet section 7.

[0147] In other words, the first electrical conductors 18 of the first coil 8 and the second electrical conductors 18 of the second coil 9 develop inclined between the inlet section 6 and the outlet section 7 of the channel 3.

[0148] In more detail, the first conductors 17 of the first coil 8 define, in their forward path, a first angle with the development axis Z. Differently, the first conductors 17 of the first coil 8 define, in their return path, a second angle with the development axis Z, of equal width with respect to the first angle but of opposite direction with respect to the first angle.

[0149] In this way, in top plan view, the first conductors 17 of the first coil 8 define a substantially cone or isosceles trapezoid shape.

[0150] Similarly, the second conductors 18 of the second coil 9 define, in their forward path, a third angle with the development axis Z. Differently, the second conductors 18 ofthe second coil 9 define, in their return path, a fourth angle with the development axis Z, of equal width with respect to the third angle but of opposite direction with respect to the third angle itself.

[0151] ] In this way, in side view, the second conductors 18 of the second coil 9 define a substantially cone or isosceles trapezoid shape.

[0152] In accordance with a different embodiment, not illustrated in the attached figures, the conductors of the first and second coil 8, 9 can be arranged radially around the development axis Z.

[0153] In other words, the conductors of the first and second coil 8, 9 can be arranged inclined with respect to each other, each aligned along a corresponding axis passing through the development axis Z (and preferably orthogonal to the development axis Z).

[0154] Furthermore, advantageously, the housing seats 10, 11 can be made spaced from each other, for example equidistant around the development axis Z or, differently, they can be arranged at non-uniform distances, in particular based on specific needs.

[0155] The electromagnet according to the invention allows for using less electric current for the same magnetic field induced in the channel 3, compared to the electromagnets of the known art.

[0156] In fact, the magnetic field induced in the channel 3 is - as is known - directly proportional to the electric current flowing in the coils 8, 9 and is inversely proportional to the linear distance between the inner walls 4, 5 that define the channel 3 itself (distance known by the term "gap" in the technical jargon of the sector), according to the formula:NI B = u - gap wherein p is the magnetic permeability of the medium in which the magnetic field is induced (i.e. the air and / or the vacuum present in the channel 3), N is the number of turns that make up the first and / or the second coil 8, 9, I is the effective value of the current induced in the first and / or the second coil 8, 9 and "gap" is the linear distance between the inner walls 4, 5 that define the channel 3.

[0157] In more detail, the gap is defined between the inner walls 4, 5 in ferromagnetic material of the yoke 2.

[0158] The electromagnet according to the invention is provided with conductors 17, 18 of the coils 8, 9 housed inside corresponding seats arranged side by side and made on the inner walls 4, 5 of the yoke 2.

[0159] In this way, with respect to the electromagnets of the known art, the coils do notinterfere with and do not enlarge the gap which can instead be measured simply as the linear distance between two opposite inner walls (identified with L in the attached figure 5B for convenience).

[0160] Therefore, for the same magnetic field to be generated in the channel 3, the electromagnet according to the invention has a smaller gap compared to the electromagnets of the known art, leading to a reduction of the current required in the coils 8, 9.

[0161] Furthermore, the electromagnet according to the invention allows for using more economical power supplies to electrically supply the coils 8, 9 compared to the electromagnets of the known art.

[0162] In fact, unlike the scanning magnets of the known art (in which the coils cover the inner walls that define the channel, consequently increasing the gap), the scanning electromagnet object of the present invention has, for the same extension of the channel 3, a smaller gap (as the coils 8, 9 do not entirely cover the inner walls, but are differently arranged inside corresponding housing seats).

[0163] Furthermore, advantageously, thanks to the quadrangular shape of the channel 3, the gap between two opposite walls remains constant along their length. This allows for having an optimal field quality in the entire area of the cross-section of the channel 3.

[0164] In fact, in addition to the aforementioned lower current required, a further advantage lies in the fact that the supply voltage is lower, for the same operation.

[0165] More clearly, as is known per se, the supply voltage of the coils 8, 9 is calculated as the sum of the resistive component and the inductive component, in which the latter depends on the derivative of the supply current of the coils 8, 9 over time, i.e. on its variability during use, according to the formula: dlV = RI + L — dtWherein V is the supply voltage of the coils 8, 9, R is the resistance of the coils 8, 9, I is the supply current, L is the self-induction coefficient of the coils 8, 9.

[0166] In the electromagnets used in hadrontherapy, the supply current can vary with speeds of the order of 200 kA / s. Therefore, the inductive component is the dominant factor in evaluating the voltage that the power supplies must be able to generate.

[0167] The inductance is also directly proportional to the magnetic energy E stored in the electromagnet, according to the formula:

[0168] The magnetic energy E stored in the electromagnet 1 can also be expressedwith the following formula (valid in the case where the channel 3 has a square shape, in accordance with the preferential embodiment of the present invention illustrated in the attached figures):Wherein Lmis the magnetic length of the electromagnet (known per se to the person skilled in the art and therefore not further commented on below), q is a corrective coefficient.

[0169] In light of the above, where the gap is smaller compared to the electromagnets of the known art, it is apparent that the energy stored inside the electromagnet 1 according to the invention is lower.

[0170] It follows that, for the same current flowing through the conductors, the inductance associated with the first and second coils 8, 9 is also lower compared to the electromagnets of the known art, thus being able to reduce the voltage that the power supplies are required to generate.

[0171] In accordance with the third embodiment of the electromagnet 1 illustrated in the attached figure 9, the teeth 13 can have a variable extension and can protrude at least partially inside the channel 3, i.e. they can protrude beyond the outer wall 12 of the corresponding coil 8, 9.

[0172] The geometry of the yoke 2, and in particular of the teeth 13, in accordance with the third embodiment, allows to strongly mitigate the phenomenon of eddy currents. In fact, the scanning magnets are intrinsically subject to a large variation in current and magnetic field over time; this variation of current induces eddy currents in the yoke, deteriorating the quality of the field during the transient.

[0173] In particular, the teeth 13 provided at the end edges of the inner walls 4, 5 can be provided with a greater length than the other teeth 13, for the purpose of improving the quality and / or uniformity of the magnetic field inside the channel 3.

[0174] In accordance with the fourth embodiment of the present invention illustrated in the attached figure 10, the electrical conductors 17, 18 of the first and / or second coil 8, 9 can have the outer wall 12 protruding inside the channel 3.

[0175] In other words, advantageously, each electrical conductor of said first coil 8 and / or said second coil 9 comprises a first portion completely housed inside said housing seat of said first group 10 and / or said second group 11 .

[0176] Furthermore, preferably, each electrical conductor of said first coil 8 and / or said second coil 9 comprises a second portion protruding from said opening of said housingseat, at least partially occupying said channel 3.

[0177] In this way, it is possible to increase the cross-section of the electrical conductors 17, 18, leading to a lower current density inside them.

[0178] This provision is possible as, following some tests, it has emerged that the quality of the field in proximity to the inner walls 4, 5 is lower than at the centre of the channel 3.

[0179] Therefore, in light of the poor quality of the magnetic field, it is possible to provide for exploiting a smaller area of the channel 3, closer to its centre, and to increase the cross-sectional area of the electrical conductors.

[0180] In accordance with the fifth and sixth embodiments of the present invention illustrated in the attached figures 11 and 12, it is possible to reduce the gap, i.e. the linear distance between the opposite inner walls 4, 5.

[0181] In accordance with a different embodiment not illustrated in the attached figures, the teeth 13 can have a protrusion in the channel 3 that is variable along / parallel to the extension of the development axis Z.

[0182] In other words, it is possible to modulate the penetration / shape of the electromagnet 1 according to the invention, which can comprise conductors of the coils 8, 9 and respective housing seats made in the yoke 2 of variable shape, so as to define the channel 3 provided with a variable width along the development axis Z, for example to follow the shape of the particle beam suited to widen in the channel 3, between the inlet section 6 and the outlet section 7.

[0183] For the purpose of following the shape of the particle beam (which widens between the inlet section 6 and the outlet section 7), in accordance with the aforementioned embodiment, the electromagnet according to the invention can have the shape and / or penetration of the teeth 13 inside the channel 3 that are variable parallel to the development axis Z, while keeping the shape of the conductors of the coils 8, 9 constant.

[0184] Differently, the electromagnet according to the invention can have the shape and / or penetration of the teeth 13 inside the channel 3 that are variable parallel to the development axis Z and, at the same time, can have the shape of the conductors of the coils 8, 9 that are variable parallel to the development axis Z.

[0185] In more detail, the teeth 13 can protrude into the channel with respect to the outer wall 12 of the conductors 17, 18.

[0186] Preferably, the scanning electromagnet 1 according to the invention, in any of its embodiments, is intended to be used in high power and / or energy applications.

[0187] Preferably, the scanning electromagnet 1 is intended to be used to deflect a beam of charged particles with an energy greater than or equal to 100 KeV.

[0188] In particular, to accelerate protons or carbon ions, the scanning electromagnet 1 is intended to be used to deflect a beam of charged particles with an energy between 60 MeV and 430 MeV.

[0189] Preferably, the scanning electromagnet 1 is intended to be used to deflect a beam of charged particles with a field rigidity between 1 Tm and 10 Tm.

[0190] For example, for applications of treatment with protons, i.e. in which the particle beam is made up of protons, the energy of the particles is between 60-250 MeV and the rigidity of the beam Bp is between 1.1 and 2.4 Tm.

[0191] For example, furthermore, for applications of treatment with carbon ions, i.e. in which the particle beam is composed of carbon atoms, the energy of the particles is between 120-430 MeV / u (where "u" means energy per nucleon) and the rigidity of the beam Bp is between 3.3 and 6.6 Tm.

[0192] Preferably, the first coil 8 is supplied by a first electric current and the second coil 9 is supplied by a second electric current independent of the first electric current.

[0193] In other words, the first electric current that supplies the first coil 8 and the second electric current that supplies the second coil 9 are generated and controlled on the basis of the deflection to be imposed on the particle beam. However, the first electric current and the second electric current are not linked by a precise phase shift angle to define their width.

[0194] In other words, the first current and the second current do not follow a polar trend, unlike the known art.

[0195] In this way, it is possible to vary the shape of the channel 3 (with respect to the circular shape, imposed by the operation of the magnets of the known art) and, at the same time, increase the energy efficiency of the scanning electromagnet 1.

[0196] The present invention is realizable in other variants all falling within the scope of the claimed and described inventive characteristics; these technical characteristics can be replaced by different technically equivalent elements and the materials used; the shapes and dimensions of the invention can be any as long as they are compatible with its use.

[0197] The reference numbers and signs inserted in the claims and in the description have the sole purpose of increasing the clarity of the text and should not be considered as elements that limit the technical interpretation of the objects or processes identified by them.

Claims

CLAIMS1. Scanning electromagnet, configured to deflect and / or direct a beam of electrically charged particles, comprising:- at least one yoke (2), made of ferromagnetic material and configured to concatenate a magnetic field flux; said yoke (2) comprising at least a first pair of internal walls (4) opposite each other and at least a second pair of internal walls (5) opposite each other, which delimit between them at least one channel (3) configured to be crossed by said particle beam and extending along a development axis Z between an inlet section (6) and an outlet section (7);- at least a first electric coil (8), mechanically and magnetically coupled to said yoke (2), configured to generate a first magnetic field, at least in said channel (3), directed parallel to a first axis X, transversely with respect to said development axis Z;- at least a second electric coil (9), mechanically and magnetically coupled to said yoke (2), configured to generate a second magnetic field, at least in said channel (3), directed parallel to a second axis Y, different from said first axis X, transversely with respect to said development axis Z; characterized in that said yoke (2) comprises a first group (10) of housing seats made on said first pair of inner walls (4) and a second group (11) of housing seats made on said second pair of inner walls (5); said first coil (8) being at least partially housed in said first group (10) of housing seats in such a way as to generate said first magnetic field in said channel (3) parallel to said first axis X; said second coil (9) being at least partially housed in said second group (11) of housing seats in such a way as to generate said second magnetic field in said channel (3), parallel to said second axis Y; said first pair of inner walls (4) and said second pair of inner walls (5) defining four sides of said channel (3), which has a substantially quadrangular shape.

2. Scanning electromagnet according to claim 1 , characterized in that each of said coils (8, 9) being configured to generate a corresponding magnetic field placed across said quadrangular channel (3), wherein said first coil (8) generates a first magnetic field transverse to said first pair (4) of inner walls and wherein the second coil(9) generates a second magnetic field transverse to said second pair (5) of inner walls.

3. Scanning electromagnet according to claim 1 or 2, characterized in that each said housing seat of said first group (10) extends between an opening made on said first pair of inner walls (4) and an opposite bottom wall; and in that each said housing seat of said second group (11) extends between an opening made on said second pair of inner walls (5) and an opposite bottom wall.

4. Scanning electromagnet according to one or more of the preceding claims, characterized in that each said housing seat of said first group (10) and / or said second group (11) extends between an opening (14) made on said first pair of inner walls (4) and an opposite bottom wall (15); said first electric coil (8) and / or said second electric coil (9) comprising at least one outer wall (12) facing said channel (3); said outer wall (12) being provided at said opening (14) of the corresponding housing seat.

5. Scanning electromagnet according to one or more of the preceding claims, characterized in that said first pair of inner walls (4) comprises at least a first inner wall (4'), which is provided with a plurality of first seats (10') of said first group (10) arranged side by side; said first electric coil (8) comprising a plurality of electrical conductors housed each at least in a corresponding said first seat (10') of said first group (10) of housing seats.

6. Scanning electromagnet according to one or more of the preceding claims, characterized in that said second pair of inner walls (5) comprises at least a third inner wall (5'), which is provided with a plurality of third seats (1 T) of said second group (11) arranged side by side; said second electric coil (9) comprising a plurality of electrical conductors housed each at least in a corresponding said third seat (1 T) of said second group of housing seats (11).

7. Scanning electromagnet according to one or more of the preceding claims, characterized in that each electrical conductor of said first coil (8) and / or of said second coil (9) comprises:- a first portion completely housed inside said housing seat of said first group (10) and / or said second group (11);- a second portion protruding from said opening of said housing seat, occupying at least partially said channel (3).

8. Scanning electromagnet according to one or more of the preceding claims,characterized in that said yoke (2) made of ferromagnetic material comprises a plurality of teeth (13), configured to guide said magnetic field, in such a way that the field lines of said magnetic field cross said channel (3) remaining parallel to each other.

9. Scanning electromagnet according to one or more of the preceding claims, characterized in that said inner walls (4', 4") of said first pair of inner walls (4) are parallel to each other; said inner walls (5', 5") of said second pair of inner walls (5) are parallel to each other and transverse with respect to said inner walls (4', 4") of said first pair of inner walls (4).

10. Scanning electromagnet according to one or more of the preceding claims, characterized in that said channel (3) is provided with a minimum width at said inlet section (6), and a maximum width at said outlet section (7); said width of said channel (3) increasing along said development axis Z between said inlet section (6) and said outlet section (7).

11. Scanning electromagnet according to one or more of the preceding claims, characterized in that of being intended for use in deflecting a beam of charged particles at an energy greater than or equal to 100 KeV.

12. Scanning electromagnet according to one or more of the preceding claims, characterized in that each said inner wall (4', 4", 5', 5") comprises a plurality of respective teeth (13), which remain defined between the corresponding housing seats of said first and second group (10, 11).

13. Scanning electromagnet according to one or more of the preceding claims, characterized in that said first magnetic field generated by said first coil (8) intercepts and flows in said teeth (13) of the first pair of walls (4', 4"), wherein said teeth (13) remain defined between the housing seats of said first group (10).

14. Scanning electromagnet according to one or more of the preceding claims, characterized in that said second magnetic field generated by said second coil (9) intercepts and flows in said teeth (13) of said second pair of walls (5', 5"), wherein said teeth (13) remain defined between the housing seats of said second group (11).

15. Scanning electromagnet according to one or more of the preceding claims, characterized in that said first coil (8) is supplied by a first electric current and said second coil (9) is supplied by a second electric current independent of said first electric current.

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