Microwave medical imaging system

Abstract

The invention relates to a microwave medical imaging system comprising - a hollow cylindrical tank arranged around a vertical axis of revolution XX, the tank being intended to accommodate a medium of human tissue to be observed; - an antenna array placed around the tank, the array being suitable for being moved vertically along the tank, the antenna array comprising: - an annular antenna support arranged around the tank and coaxially with respect to the tank, the antenna support comprising an outer radius and an inner radius defining a ring, the antenna support comprising a plurality of locations formed in angular sectors of the ring; - a set of microwave transmission / reception probes, each probe comprising a body extending in a location in a radial direction from the ring in the direction of the axis XX, wherein a radiating element is arranged at the end of the body and projects from the support in the direction of the axis XX, wherein the locations on the support are regularly distributed in such a way that an angular spacing between each probe is constant around the tank, even during the vertical movement of the antenna array along the tank, wherein the support is such that the probes are arranged in the same plane defined by the lower surface of the locations, even during the vertical movement of the antenna array along the tank, and wherein the antenna array and the tank are configured and arranged relative to one another so that each radiating element is in contact with the tank, even during the vertical movement of the antenna array along the tank.

Description

[0001] Microwave medical imaging system

[0002] TECHNICAL FIELD

[0003] The invention relates to a microwave medical imaging system. More particularly, the invention relates to an imaging system of this type for the analysis of human tissues or organs permeable to electromagnetic waves. And the invention finds particular application in breast imaging in the context of screening, diagnosis and monitoring of breast cancer.

[0004] STATE OF THE ART

[0005] In microwave imaging systems, the choice of the transition material between the antennas and the medium under observation is important in order to reduce the reflection of waves at the interface of the medium under observation and thus to promote the penetration of waves into this medium under observation. The dielectric characteristics of the transition material must be selected according to the medium to be observed, so as to obtain better results in terms of image reconstruction.

[0006] Ideally, a liquid or gel is most often used as a transition material because this allows the space inside a container between the antennas and the medium under observation to be completely filled in a universal manner, without the presence of air gaps, regardless of the shape of the breast; the antennas are immersed in this liquid or gel with the biological tissues to be imaged so as to allow transmission of waves directly between the antennas and the tissues through a single homogeneous medium, without the presence of air gaps that are sources of wave reflections and artifacts in the reconstructed images.Furthermore, the appropriate choice of a liquid or gel with moderate losses makes it possible to level the values ​​of the signals from multi-paths (signals propagating in the liquid or gel between the walls of the container and the medium under observation, said signals remaining confined outside the medium under observation) compared to the low levels of useful signals coming from echoes from inside the medium under observation.

[0007] However, this presents difficulties and complexity in terms of (i) sealing for cable passages, connections and the implementation of the emission / reception probe supports which can also be mobile, (ii) possible contact between the probes and the environment under observation and therefore safety for patients, (iii) cleaning and hygiene.

[0008] STATEMENT OF THE INVENTION

[0009] The invention proposes to overcome at least one of these drawbacks.

[0010] For this purpose, the invention proposes an imaging system comprising

[0011] - a hollow cylindrical tank arranged around a vertical axis of revolution XX, the tank being intended to receive a medium of human tissue to be observed;

[0012] - an antenna network placed around the tank, the network being adapted to move vertically along the tank, the antenna network comprising:

[0013] - an annular antenna support arranged around the tank coaxially with the tank, the antenna support comprising an external radius and an internal radius defining a crown, the antenna support comprising several locations formed in angular sectors of the crown,

[0014] - a set of microwave transmitting / receiving probes, each probe comprising a body extending in a location in a radial direction taken from the crown towards the axis XX and a radiating element being arranged at the end of the body and projecting from the support towards the axis XX, the locations of the support being distributed regularly in such a way that an angular spacing between each probe is constant around the tank, even during the vertical movement of the antenna array along the tank, the support being such that the probes are arranged in the same plane defined by the lower surface of the locations, even during the vertical movement of the antenna array along the tank, the antenna array and the tank being configured and arranged relative to each other so that each radiating element is in contact with the tank, even during the vertical movement of the antenna array along the tank.

[0015] The invention is advantageously supplemented by the following characteristics, taken alone or in any of their technically possible combinations: - the surface of the radiating element is flat and is arranged perpendicular to a radial direction of each location.

[0016] - the tank comprises on its external surface a network of facets having flat surfaces, each facet extending over the height of the tank, the tank being configured so that the flat surface of the radiating element of each transmission / reception probe is in contact with the flat surface of a facet of the tank, even during the vertical movement of the antenna network along the tank.

[0017] - the imaging system may include a probe holding system configured to ensure clear contact with pressure and without air gap between the tank and the probes, even during vertical movement of the antenna array along the tank.

[0018] - the probe holding system is configured to compensate for any misalignment between the axis of revolution of the antenna support and the axis of revolution of the tank so as to maintain contact between the tank and the probes even in the presence of misalignment between said axes.

[0019] - the antenna network support is made of PEEK type plastic.

[0020] - the imaging system comprises a system for vertical movement of the antenna array, the system for vertical movement of the antenna array comprising an annular central member coaxial with the tank and with the antenna array and a plurality of arms extending radially from the central member away from the axis XX, the central member being movable along a guide support extending along the axis XX and coaxial with the central member, each arm being distributed regularly around the central member and supporting at its end a holding rod extending in a vertical direction towards the support of the antenna array, each rod being connected to the support of the antenna array.

[0021] - the imaging system comprises a hollow cylindrical support on which the tank is arranged and housing the system (5) for vertical movement of the antenna array, the cylindrical support comprising guide orifices through which the holding rods pass, the orifices being arranged around the tank so that the vertical axis of revolution of the circle passing through the centers of the orifices is coaxial with the axis XX of revolution of the tank, the orifices being adapted to guide the rods.

[0022] - the imaging system comprises a sliding system connecting each arm to each holding rod such that each holding rod is connected to an arm so as to allow sliding in the horizontal plane between the lower ends of the holding rods and the ends of the arms, to compensate for any misalignment between the axis of revolution of the circle passing through the ends of the arms and the axis of revolution of the circle passing through the centers of the guide holes, during vertical movement of the antenna array.

[0023] - the vertical movement system of the antenna network comprises three arms distributed every 120° around the central organ.

[0024] - each holding rod is made of PEEK type plastic material, the sliding system is made of metal, and each arm is made of metal.

[0025] - the vertical movement system of the antenna network includes a vertical adjustment system for each holding rod so as to adjust the horizontality of the antenna network support.

[0026] - the imaging system comprises a thermoregulation unit configured to control the temperature of the microwave medical imaging system so as to (i) stabilize characteristics of the internal components in terms of radio-frequency performance, and (ii) stabilize the temperature of a transition liquid filling the tank and thus the dielectric properties of the tissues immersed in the transition liquid during use of the imaging system.

[0027] The advantages of the invention are multiple.

[0028] By placing the transmitting / receiving probes outside the tank, the system of the invention does not present any problems of sealing, contact with tissues and safety for patients, cleaning and hygiene. Furthermore, the movements of the probes are easier to implement.

[0029] The direct contact between the tank and the probes allows transmission without the presence of air gaps between the probes and the interior of the tank containing the transition material and the medium to be observed, thus avoiding sources of artifacts in the reconstructed images.

[0030] The invention addresses the specific issues relating to an architecture using microwaves and implementing a circular network of transmission / reception probes:

[0031] - moving outside a cylindrical tank which contains a liquid transition medium in which the breast to be scanned is immersed,

[0032] - operating in the microwave frequency range, placed in a closed enclosure; and - subjected to thermal constraints, said invention allowing the improvement of the multifactorial stability of the imaging system (mechanical, thermal and radiofrequency stabilities) and the optimization of the propagation of waves from the probes to the interior of the breast to be imaged.

[0033] The invention also makes it possible to stabilize and make repeatable the values ​​of the couplings between the probes throughout the vertical path of the antenna array and thus to be able to more effectively subtract these said couplings from the signals received by the probes to better identify the low levels of useful signals coming from the echoes from inside the breast.

[0034] PRESENTATION OF FIGURES

[0035] Other characteristics, aims and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the appended drawings in which:

[0036] - figure 1a and figure 1b illustrate overall views of a microwave medical imaging system according to the invention;

[0037] - figure 2a and figure 2b illustrate a top view of a tank and an antenna network of a microwave medical imaging system according to the invention;

[0038] - figure 3 illustrates a perspective view of a tank and an antenna network of a microwave medical imaging system according to the invention;

[0039] - figure 4 illustrates a perspective view of an annular antenna support of an antenna array of a microwave medical imaging system according to the invention;

[0040] - figure 5 illustrates an antenna network of a microwave medical imaging system according to the invention;

[0041] - figure 6 and figure 7 illustrate a system for holding the probes of an antenna network of a microwave medical imaging system according to the invention;

[0042] - figure 8, figure 9 and figure 10 illustrate a tank of a microwave medical imaging system according to the invention;

[0043] - figure 11 illustrates a system for vertical movement of an antenna array of a microwave medical imaging system according to the invention;

[0044] - Figure 12 and Figure 13 illustrate a system for vertical adjustment and compensation of mechanical misalignments in the horizontal plane in a microwave medical imaging system according to the invention. In all the figures, similar elements bear identical references.

[0045] DETAILED DESCRIPTION

[0046] System Overview

[0047] Figures 1a, 1b, 2a, 2b and 3 illustrate views of a microwave medical imaging system 1 according to the invention.

[0048] Such a system comprises an examination table 11 placed above a hollow enclosure 12 which houses various pieces of equipment of the system. The system 1 is advantageously equipped with stairs 13 with a protective ramp 14 to facilitate access to the examination table 11, removable casters 17 to allow it to be moved during installation and retractable feet 18 to stabilize it once installed. In addition, a control panel 15 composed of a screen, a keyboard and possibly a mouse makes it possible to control the imaging system 1. Also, the system 1 comprises a thermoregulation unit 9 arranged behind a ventilation grille 10.

[0049] The examination table 11 is designed so that a patient can lie on their stomach so that a breast (which constitutes the tissue to be imaged) is positioned in an opening 16 made in the center of a slightly conical area 19 of the examination table 11. This opening 16 (circular) provides access to the opening of a tank 2 which contains a transition liquid and in which the breast is then immersed. The transition liquid fills the tank 2 in which the breast is immersed. Thus, the opening 16 is surrounded by a conical peripheral area 19 which allows better introduction of the breast into the opening 16. Around the opening 16 of the tank 2 the area is therefore not flat.

[0050] Preferably, the transition liquid is slightly creamy and sticky and allows the space between the inner walls of the tank 2 and any shape of breast immersed therein to be universally filled, without the presence of air gaps. The use of the liquid as a transition material has an advantage over the use of solid shells which cannot adapt to all shapes and sizes of breasts and which do not allow the absence of air gaps between the inner walls of the shells and the skin of the breast (see for example document WO 2014 / 195502 A1). The tank 2 is cylindrical and hollow and is arranged around a vertical axis of revolution XX. An antenna array 3 is placed around the tank 2, the array 3 being adapted to move vertically along the tank 2. In this way, it is possible to carry out acquisitions according to several configurations around the tissue to be imaged.

[0051] In particular, the 3-antenna network allows multistatic measurements to be carried out, with the possibility of sectoring the measurements to carry out imaging of heterogeneous tissues such as those constituting the breast, in a lossy propagation medium represented by the transition liquid and the breast tissues. In this respect, reference may be made to documents WO 2022 / 234234 A1 and WO 2022 / 234235 A1.

[0052] The antenna network 3 comprises an annular antenna support 31 arranged around the tank 2 and housing several microwave probes 32, each comprising a body 33 and a radiating element 34 arranged at one end of the body 33 directed along the radial direction towards the axis XX.

[0053] Advantageously, the tank 2 is arranged on a hollow cylindrical support 6 which houses a system 5 for vertical movement of the antenna network 3. For this purpose and advantageously, the antenna network 3 is arranged on holding rods 55 of the vertical movement system 5, these rods passing through guide orifices 61 through the support 6. The support e is arranged in the enclosure 12 under the examination table 11.

[0054] As will be described in detail, the microwave medical imaging system according to the invention is remarkable in that the antenna array 3 and the tank 2 are configured and arranged relative to each other so that each radiating element 34 of each probe 32 is in direct contact and without the presence of an air gap with the tank 2, even during the vertical movement of the antenna array 3 along the tank 2.

[0055] Antenna network

[0056] As can be seen in particular in Figures 4 and 5, the antenna support 31 of the antenna array 3 is annular and is arranged around the tank 2 coaxially with the tank 2. The antenna support 31 comprises an external radius r1 and an internal radius r2 defining a crown. The antenna support 31 comprises several locations 35 which are formed in angular sectors of the crown. Figure 4 illustrates the antenna support 31 alone while Figure 5 illustrates the antenna support 31 with the microwave probes 32.

[0057] In relation to figures 6 and 7, each location 35 therefore houses a microwave probe 32 whose body 33 extends in a radial direction taken from the crown towards the axis XX, a radiating element 34 being arranged at the end of the body 33 projecting from the antenna support 31 and oriented towards the axis XX.

[0058] Preferably, the antenna support 31 is a monolithic part which is made of PEEK type plastic material combining significant mechanical rigidity (mechanical stability) and low dielectric permittivity (reduced influence on the radiation of the probes). The antenna support 31 which is therefore rigid makes it possible to ensure the positioning of all the bodies 33 of the probes of the antenna network in the same defined horizontal plane, stable and perpendicular to the axis XX of the tank 2. In this way, all the probes of the antenna network are positioned in the same plane (the lower surfaces of the locations 35 defining the single plane of positioning of the probes), throughout the vertical excursion of the antenna network along the tank 2 during a scan using the probes.

[0059] Furthermore, the locations 35 are distributed regularly so that the angular spacing between each probe is identical and constant around the tank 2.

[0060] The antenna support 31 therefore makes it possible to maintain constant the positions of the probes 32 between them within the antenna network 3, both in the same plane and angularly and thus to stabilize and make repeatable the values ​​of the couplings between probes throughout the vertical path of the antenna network. This makes it possible to more effectively subtract these said couplings from the signals received by the probes in order to better be able to identify the low levels of the useful signals coming from the echoes from inside the breast.

[0061] The probes 32 and the antenna support 31 which constitute the antenna network 3 are arranged relative to the tank 2 so that each radiating element 34 of each probe is in contact with the tank 2.

[0062] In a complementary manner and to promote a clean contact between the tank 2 and the probes 32 (in particular between the tank 2 and the radiating elements 34) and this even during the vertical movement of the antenna network along the tank, the antenna network comprises a system 4 for holding the probes against the tank 2. It is noted that by clean contact we mean that the contact is made with pressure and without the presence of air gaps between the radiating element 34 and the tank 2.

[0063] Such a holding system 4 as visible in figures 6 and 7 comprises springs 41 each placed behind each probe 32 and associated with a radial sliding mechanism of the probes, said radial sliding of each probe being guided precisely by the walls of each location 35. Advantageously, a lubricant is used between the walls of the locations 35 of the probes and the bodies 33 of the probes in order to ensure optimal radial translation without blocking of the probes.

[0064] Such a maintenance system 4 therefore allows

[0065] - to ensure contact with pressure and without air gap between the radiating elements 34 of the probes and the tank, throughout the vertical excursion of the antenna network along the tank during a scan;

[0066] - to introduce a degree of freedom for the probes following the radial direction in order to be able to compensate for variations in the external diameter and the circularity of the tank, as well as a misalignment between the axis of revolution of the annular antenna support 31 of the antenna array and the axis XX of revolution of the tank 2, throughout the vertical excursion of the antenna array along the tank during a scan.

[0067] Such misalignment is for example due to manufacturing and assembly tolerances of the antenna array 31.

[0068] This system thus guarantees wave propagation without reflection at the interface which would be due to poor contact between probes and tank, and maximizes the power transmitted inside the tank, throughout the vertical path of the antenna network.

[0069] To obtain a clean contact, the surface of each radiating element 34 in contact with the tank 2 is flat and is arranged perpendicular to a radial direction of each location 35.

[0070] Such a characteristic is combined with the tank 2 whose geometry of the outer wall is such that it makes it possible to define a contact between two flat surfaces between each radiating element 34 and the tank 2.

[0071] Cylindrical tank

[0072] As illustrated in Figures 8, 9 and 10, the tank 2 is a hollow cylinder and has an internal surface 21 and an external surface 22. The external surface is advantageously faceted to, in combination with the flat surfaces of the radiating elements 34 of the probes 32, promote clear contact between each probe and the tank 2.

[0073] In particular, several facets 23 extend over the entire height of the tank 2 so as to define flat surfaces over the entire height.

[0074] The facets have central axes distributed around a radius r rep which is defined between an external radius r ex t and an internal radius n n t of tank 2.

[0075] The contact between the radiating element 34 of each of the probes 32 and the tank 2 is made between two placed surfaces.

[0076] Tank 2 is made of dielectric material allowing the transmission of electromagnetic waves.

[0077] The tank 2 thus defined, combined with the flat surfaces of the radiating elements, allows propagation of the wave without reflections at the interface which would be due to poor contact between probe and tank and thus maximizes the power transmitted inside the tank throughout the vertical path of the antenna network.

[0078] System for holding the probes against the tank

[0079] Returning to Figures 6 and 7, the holding system 4 comprises, for each probe, a spring 41 placed at the rear of the probe making it possible to push the probe 32 forward (i.e. towards the axis XX) by means of a combination of mechanical axes 43, 45, 46. The stiffness of the spring is chosen to push the probe with sufficient force to press the radiating element 34 with sufficient pressure against the tank 2. Advantageously, the pushing force produced by the spring can be between 20 and 50 Newtons.

[0080] The spring 41 is supported by a radial rod 42 connected to a fork 44 by means of a first movable mechanical rotation axis 43 which is integral with the fork 44. The fork 44 is mounted movable around a second fixed mechanical rotation axis 45 integral with the support 31 and is connected to the probe 32 by means of a third movable mechanical rotation axis 46 integral with the body 33 of the probe 32. The fork 44 is therefore rotating around the second axis 45 when a force is applied to the first axis 43 by the radial rod 42. The fork 44 comprises a base 44a from which two arms 44b, 44c extend from each end of the base 44a, the arms 44b, 44c being parallel, the fork 44 having a U-shape. It is the base 44a which is connected to the first axis 43 and arms 44b, 44c are arranged on either side of the second 45 and third 46 axes.

[0081] The spring 41 comprises a front end 41a in fixed abutment on the support 31 (support 31 not visible in figure 6, visible in figure 7) and a rear end 41b in movable abutment on a ring 47 secured to the radial rod 42. The spring 41 is mounted in a pre-compressed manner between these two stops and therefore seeks to lengthen between these two stops.

[0082] The operation of the 4 maintenance system is as follows:

[0083] - the spring 41 mounted in a pre-compressed manner pushes on the ring 47 secured to the radial rod 42.

[0084] - the thrust of the spring 41 thus moves the radial rod 42 backwards which drives the first movable mechanical axis 43 of rotation secured to the base 44a of the fork 44 backwards.

[0085] - the rearward movement of the first mechanical rotation axis 43 thus pivots the two arms 44b, 44c of the fork 44 forward around the second fixed mechanical rotation axis 45 secured to the support 31.

[0086] - the two arms of the fork, by pivoting forward, move the probe forward using the third mechanical axis 46 which is mobile for rotation and secured to the body 33 of the probe.

[0087] - pressure contact between the radiating openings 34 of the probes and the tank 2 is thus ensured.

[0088] Vertical displacement system of the antenna array

[0089] To move the antenna network 3 along the tank 2, as visible in FIG. 11, a system 5 for vertically moving the antenna network 3 comprises a central annular member 51 coaxial with the tank 2 and with the antenna network 3. The member 51 is movable along a central guide support 53 extending along the axis XX and coaxial with the central member 51. The guide support 53 has the shape of a shaft.

[0090] From the central member 51, three arms 52a, 52b, 52c extend radially away from the axis XX. These arms are advantageously distributed every 120° around the central member.

[0091] Advantageously, the central member 51 and the arms 52a, 52b, 52c constitute a single piece and the arms are all arranged in the same horizontal plane. The member 51 and the arms 52a, 52b, 52c are preferably metallic and very rigid.

[0092] Each end 54a, 54b, 54c of each arm 52a, 52b, 52c supports a holding rod 55a, 55b, 55c which extends vertically towards the antenna support 31, each holding rod 55a, 55b, 55c is connected to the antenna support 31 as visible in FIG. 11.

[0093] The holding rods 55a, 55b, 55c pass through the hollow cylindrical support 6, housing the vertical displacement system 5, through guide orifices 61 which allow, in addition to passing the rods, to guide them precisely during the vertical displacement of the antenna array. The circle passing through the centers of the guide orifices 61 has its axis of revolution coaxial with the axis XX of revolution of the tank 2. Thanks to these precise guide orifices 61 of the rods, the support of the antenna array does not rotate on itself (it is blocked in rotation) and the probes remain centered along the facets of the tank 2, throughout the vertical excursion of the antenna array along the tank during a scan.

[0094] The holding rods 55a, 55b, 55c are made of PEEK type plastic material combining significant mechanical rigidity and low dielectric permittivity (reduced reflectivity limiting the influence of the rods on the radiation of the probes).

[0095] Furthermore, each holding rod 55a, 55b, 55c is connected to an arm 52a, 52b, 52c in such a way as to allow sliding between the rods and the arms in the horizontal plane to compensate for a misalignment between the axis of revolution of the circle passing through the ends 54a, 54b, 54c of the arms 52a, 52b, 52c and the axis XX of revolution of the circle passing through the centers of the guide orifices 61, throughout the vertical excursion of the antenna array along the tank during a scan.

[0096] To do this, the connection between an arm and a rod is made by means of a sliding system 7 in the horizontal plane visible in Figures 12 and 13 which comprises a metal upper base 81 connected to a holding rod 55a by means of, for example, one or more screws 88. The metal upper base 81 comprises a housing 83 in which is arranged a T-shaped head of a metal rod 82 which extends towards a lower base 85 constituted by the end 54a of the arm 52a. The dimensions of the housing 83 are such that they make it possible to house the T-shaped head of the rod 82 while ensuring the existence of a clearance all around said head. Due to the presence of this clearance, the T-shaped head thus has the possibility of sliding in the different directions in the horizontal plane. A spring 84 is compressed between the lower base 85 and the upper base 81 and surrounds the rod 82.This spring 84 pushes the upper base 81 upwards. The stiffness of the spring 84 makes it possible to keep the upper base constantly in abutment under the T-shaped head of the rod 82, which ensures compliance with the chain of ribs in the vertical direction and precise and repeatable positioning of the antenna network 3, while maintaining the possibility of sliding in the horizontal plane.

[0097] In this way, the sliding system 7 in the horizontal plane allows a relative movement between the lower ends of the rods 55 and the ends 54 of the arms 52 allowing the compensation of a misalignment between the axis of revolution of the circle passing through the ends 54a, 54b, 54c of the arms 52a, 52b, 52c and the axis XX of revolution of the circle passing through the centers of the guide orifices 61 of the rods which would be due, for example, to the manufacturing and assembly tolerances of the guide support 53 and of the central member 51 comprising the arms 52.

[0098] The movement system 5 of the antenna array 3 is housed in the hollow cylindrical support 6, said support being arranged under the antenna array, and is actuated by means of a motor 56 which makes it possible to move the central member 51 vertically along the guide support 53, thus driving the holding rods 55 and the antenna array. Advantageously, such a movement is implemented by a ball screw which constitutes the guide support 53 along which the central member 51 comprising an internal thread moves. Of course, other techniques can be implemented.

[0099] Vertical adjustment system of the antenna array

[0100] Still in relation to figures 12 and 13, the vertical displacement system 5 also comprises a system 8 for vertical adjustment of each holding rod 55 so as to adjust the horizontality of the antenna support 31 of the antenna network 3 so that the plane containing the probes 32 is perpendicular to the vertical axis of revolution XX of the tank 2.

[0101] The vertical adjustment system 8 uses the compressed spring 84 previously described and includes an adjustment wheel 86 which is mounted around the lower end of the central rod 82 by means of a thread 87. As previously described, the stiffness of the spring 84 pushes upwards the upper base 81 which is constantly held in abutment under the T-head of the rod 82. Similarly, the adjustment wheel 86, screwed to the central rod 82, is constantly held in abutment under the lower base 85. In the vertical adjustment system 8, the spring 84 serves to ensure contact between the underside of the T-head of the central rod 82 and the upper base 81 and contact between the adjustment wheel 86 and the lower base 85.

[0102] By operating the adjustment wheel 86 in one direction or another, the central rod 82 is translated vertically upwards or downwards. Thanks to the contact between the upper base 81 and the underside of the T-head of the rod 82, the vertical translation is transmitted to the holding rod.

[0103] The system 8 allows the vertical translation, upwards or downwards, of each of the three holding rods 55a, 55b and 55c independently and thus the very precise and repeatable adjustment of the perpendicularity of the antenna support 31 of the antenna network 3 relative to the vertical axis of revolution XX of the tank 2.

[0104] Once the horizontality of the antenna support 31 of the antenna network has been adjusted in this way, a clamping ring 89a makes it possible to hold the adjustment wheel 86 so that it can no longer turn around the thread 87, and a locking nut 89b makes it possible to prevent any disturbance during the time of this adjustment.

[0105] Thermoregulation unit

[0106] The invention also allows the improvement of the thermal and radiofrequency stability of the microwave medical imaging system by means of a thermoregulation unit 9 provided in the enclosure 12 of the imaging system. The thermoregulation unit is configured to control the temperature of the microwave medical imaging system so as to (i) stabilize the characteristics of the internal components in terms of radiofrequency performance (the characteristics of the radiofrequency components vary significantly with temperature), and (ii) stabilize the temperature of the transition liquid and thus the dielectric properties of the tissues immersed in the transition liquid during use of the system (the dielectric properties of breast tissues depend significantly on temperature).

[0107] Preferably, such a thermoregulation unit makes it possible to maintain the internal temperature of the system in a range between 22°C and 28°C. This internal operating temperature range of the imaging system ensures both (i) stabilized operation of the internal components of the scanner, (ii) maintenance of the transition liquid at an acceptable temperature for the patient's perception when the breast is immersed in the transition liquid, (iii) stabilization of the dielectric properties of the breast tissues, throughout the examination of the tissues by mitigating the increases in temperature of the transition liquid due to the operation of the internal components of the imaging system and due to the heat of the human body present on the examination table and in the tank containing the breast.

Claims

CLAIMS 1. Microwave medical imaging system, comprising - a hollow cylindrical tank (2) arranged around a vertical axis of revolution XX, the tank (2) being intended to receive a human tissue medium to be observed; - an antenna network (3) placed around the tank (2), the network (3) being adapted to move vertically along the tank (2), the antenna network comprising: - an annular antenna support (31) arranged around the tank (2) coaxially with the tank (2), the antenna support (31) comprising an external radius and an internal radius defining a crown, the antenna support (31) comprising several locations (35) formed in angular sectors of the crown, - a set of microwave transmitting / receiving probes (32), each probe comprising a body (33) extending in a location (35) in a radial direction taken from the crown towards the axis XX and a radiating element (34) being arranged at the end of the body (33) and projecting from the support (31) towards the axis XX, the locations (35) of the support (31) being distributed regularly in such a way that an angular spacing between each probe (32) is constant around the tank (2), even during the vertical movement of the antenna array along the tank (2), the support (31) being such that the probes are arranged in the same plane defined by the lower surface of the locations (35), even during the vertical movement of the antenna array along the tank (2),the antenna array (3) and the tank (2) being configured and arranged relative to each other so that each radiating element (34) is in contact with the tank (2) even during the vertical movement of the antenna array along the tank (2)., 2. System according to claim 1, wherein the surface of the radiating element (34) is planar and is arranged perpendicular to a radial direction of each location (35).

3. System according to one of the preceding claims, in which the tank (2) comprises on its external surface a network of facets (23) having flat surfaces, each facet (23) extending over the height of the tank (2), the tank (2) being configured so that the flat surface of the radiating element (34) of each transmission / reception probe is in contact with the flat surface of a facet (23) of the tank (2) even during the vertical movement of the antenna network along the tank (2).

4. System according to one of the preceding claims, comprising a system (4) for holding the probes (32) configured to ensure a clean contact with pressure and without air gap between the tank (2) and the probes (32) and this even during the vertical movement of the antenna network along the tank (2).

5. System according to claim 4, in which the system (4) for holding the probes is configured to compensate for any misalignment between the axis of revolution of the antenna support (31) and the axis of revolution of the tank (2) so as to maintain contact between the tank and the probes even in the presence of misalignment between said axes.

6. System according to one of the preceding claims, in which the support (31) of the antenna network (3) is made of PEEK type plastic material.

7. System according to one of the preceding claims, comprising a system (5) for vertical movement of the antenna array (3), the system for vertical movement of the antenna array comprising a central annular member (51) coaxial with the tank (2) and with the antenna array (3) and a plurality of arms (52a, 52b, 52c) extending radially from the central member (51) away from the axis XX, the central member (51) being movable along a guide support (53) extending along the axis XX and coaxial with the central member, each arm being distributed regularly around the central member and supporting at its end a holding rod (55a, 55b, 55c) extending in a vertical direction towards the support of the antenna array (3), each rod (55a, 55b, 55c) being connected to the support (31) of the array (3) antennal.

8. System according to claim 7, comprising a hollow cylindrical support (6) on which the tank (2) is arranged and housing the system (5) for vertical movement of the antenna network (3), the cylindrical support (6) comprising guide orifices (61) through which the holding rods (55a, 55b, 55c) pass, the orifices being arranged around the tank (2) so that the vertical axis of revolution of the circle passing through the centers of the orifices is coaxial with the axis XX of revolution of the tank (2), the orifices being adapted to guide the rods.

9. System according to one of claims 7 to 8, comprising a sliding system (7) connecting each arm to each holding rod so that each holding rod (55a, 55b, 55c) is connected to an arm so as to allow sliding in the horizontal plane between the lower ends of the holding rods (55a, 55b, 55c) and the ends (54a, 54b, 54c) of the arms (52a, 52b, 52c), to compensate for any misalignment between the axis of revolution of the circle passing through the ends (54a, 54b, 54c) of the arms (52a, 52b, 52c) and the axis of revolution of the circle passing through the centers of the guide orifices (61), during the vertical movement of the antenna array (3).

10. System according to one of claims 7 to 9, in which the system (5) for vertical movement of the antenna network comprises three arms distributed every 120° around the central member.

11. System according to one of claims 7 to 10, in which each holding rod (55a, 55b, 55c) is made of PEEK type plastic material, the sliding system is made of metal, and each arm is made of metal.

12. System according to one of claims 7 to 11, in which the system for vertical movement of the antenna network comprises a system (8) for vertical adjustment of each holding rod (55a, 55b, 55c) so as to adjust the horizontality of the support (31) of the antenna network (3).

13. System according to one of the preceding claims, comprising a thermoregulation unit (9) configured to control the temperature of the microwave medical imaging system so as (i) to stabilize characteristics of the internal components in terms of radio-frequency performance, and (ii) to stabilize the temperature of a transition liquid filling the tank (2) and thus the dielectric properties of the tissues immersed in the transition liquid during use of the imaging system.

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