Modular hemispherical ultrasound probe

Abstract

The invention relates to an ultrasonic probe (1) comprising a body with a hemispherical transmitting / receiving interface (6) covered with ultrasonic transducers (8) configured to emit ultrasonic waves into a hemispherical internal cavity (4), characterized in that the probe body (2) comprises at least six modules (10) carrying the ultrasonic transducers (8), each module (10) corresponding to a partition of the same surface area of ​​a hemispherical surface, and defining a spherical quadrilateral on said hemispherical surface. Figure for abstract: Figure 1b

Description

Title of the invention: Modular hemispherical ultrasound probe Technical field

[0001] The present invention relates to the field of ultrasonic transducers. More specifically, the invention relates to a hemispherical ultrasonic probe defining a hemispherical internal cavity in which ultrasonic transducers are configured to emit and / or receive ultrasonic waves.

[0002] Certain applications require a hemispherical ultrasound probe capable of carrying out ultrasound inspection or treatment of an object placed in the hemispherical internal cavity of the ultrasound probe. This is particularly the case for medical imaging or therapeutic applications, in which the object placed is, for example, a breast or the top of a head. The hemispherical shape makes it possible in particular to simultaneously use a large number of transducers (up to several thousand) forming a large emission surface, making it possible to obtain high power and / or the widest possible angular coverage, making it possible to obtain a larger imaged surface or an image obtained with better resolution or better quality (with fewer artifacts).

[0003] Such a hemispherical ultrasonic probe must therefore be large in size since it must accommodate the object to be inspected in the hemispherical internal cavity that it defines, and must be capable of accommodating a large number of elements, which poses multiple constraints. First, such a probe is complex to manufacture both due to its size and shape and due to the need to manage the interconnections between the numerous transducers and the signal processing means. Any manufacturing or operating defect in a small part of the hemispherical ultrasonic probe may make it impossible to use it. Since the transducers are arranged on a hemispherical transmission / reception interface facing the hemispherical internal cavity, it is very difficult to intervene on an ultrasonic transducer to correct a defect or replace it in the event of failure.

[0004] There is therefore a need for a hemispherical ultrasonic probe that is easy to manufacture and easy to repair. Presentation of the invention

[0005] The invention aims to remedy at least in part these drawbacks and preferably all of them, and thus proposes an ultrasonic probe comprising a body with a hemispherical transmission / reception interface covered with ultrasonic transducers configured to emit ultrasonic waves into a hemispherical internal cavity, characterized in that the body of the probe comprises at least six modules carrying the ultrasonic transducers, each module corresponding to a partition of the same surface area of ​​a hemispherical surface, and defining a spherical quadrilateral on said hemispherical surface.

[0006] The modular aspect of the ultrasonic probe makes it much easier to manufacture and maintain. For example, it is possible to replace only one module in the event of failure. Partitioning the hemispherical surface by a spherical quadrilateral ensures that the hemispherical shape of the ultrasonic probe is preserved while also making it possible to have modules whose shape allows easy assembly without introducing any weaknesses or manufacturing difficulties.

[0007] The ultrasonic probe is advantageously supplemented by the following characteristics, taken alone or in any of their technically possible combinations: - the modules are identical at least in terms of shape; - each vertex of a spherical quadrilateral of a module is adjacent to fewer than four vertices of spherical quadrilaterals of other modules; - the edges of the quadrilateral of each module are great circle arcs of the hemispherical surface; - the modules partition the hemispherical surface according to arcs of great circles obtained by rotation of 45° according to three perpendicular axes in a reference frame centered on the center of the edge of the hemispherical surface; - the body of the ultrasound probe consists of exactly 6 modules or 12 modules; - the ultrasonic transducers of a module each define a spherical quadrilateral on the hemispherical surface, the edges of the quadrilateral of each ultrasonic transducer being great circle arcs of the hemispherical surface; - each module comprises a transmission / reception face forming a part of the hemispherical transmission / reception interface, and the ultrasonic transducers are distributed on said transmission / reception face according to a network organized according to a plurality of arcs of first large circles and arcs of second large circles of the hemispherical transmission / reception interface, the first large circles passing through a first common point, the second large circles passing through a second common point, the first and second common points being separated by a quarter circle of the hemispherical transmission / reception interface; - the first large circles have a regular angular spacing between them, and / or the second large circles have a regular angular spacing between them, or in which the columns of ultrasonic transducers have the same surface area and / or the rows of ultrasonic transducers have the same surface area; - the body further comprises a frame on which the modules are mounted, and / or each module comprises a mounting structure capable of being assembled with mounting structures of other modules. Presentation of figures

[0008] The invention will be better understood, thanks to the following description, which relates to embodiments and variants according to the present invention, given as non-limiting examples and explained with reference to the appended schematic drawings, in which:

[0009] [Fig. la] [Fig. la] is a three-quarter perspective view from above showing the body of an ultrasonic probe according to a possible embodiment of the invention;

[0010] [Fig.lb] [Fig.lb] is a three-quarter perspective view from below showing the body of an ultrasonic probe according to a possible embodiment of the invention;

[0011] [Fig.2a] [Fig.2a] is an exploded view of the body of a 12-axis ultrasonic probe ultrasonic modules according to a possible embodiment of the invention;

[0012] [Fig.2b] [Fig.2b] is an exploded view of the body of a 6-axis ultrasonic probe ultrasonic modules according to a possible embodiment of the invention;

[0013] [Fig.3a] [Fig.3a] is a top view of an example of partitioning a hemispherical surface in modules of a body of an ultrasonic probe according to a possible embodiment of the invention, showing the arcs of great circles involved in said partitioning;

[0014] [Fig.3b] [Fig.3b] is a side view of the example of [Fig.3a];

[0015] [Fig.4] [Fig.4] is a three-quarter perspective view from below showing the body of an ultrasonic probe with a random distribution of the ultrasonic transducers on each module, according to a possible embodiment of the invention;

[0016] [Fig.5] [Fig.5] shows a principle of distribution of ultrasonic transducers on the part of the hemispherical transmission / reception interface of an example of an ultrasonic probe according to a possible embodiment of the invention. Detailed description

[0017] The present hemispherical ultrasound probe is preferably part of medical devices, being for example intended to be used for ultrasound or comodality imaging applications such as ultrasound, photoacoustic imaging or acoustic tomography, or for therapeutic applications. With reference to [Fig.1a] and [Fig.1b], a hemispherical ultrasound probe 1 is a probe comprising a hemispherical-shaped body 2 defining a hemispherical internal cavity 4 in which the ultrasonic waves are emitted, i.e. mechanical sound waves with a frequency greater than 20 kHz, preferably greater than 100 kHz. A hemisphere is understood to mean a portion of a sphere delimited by a plane passing through the center of the sphere.

[0018] In order to emit ultrasound, the ultrasound probe 1 comprises a hemispherical transmitting / receiving interface 6 covered with ultrasonic transducers 8, which are configured to emit ultrasonic waves into the hemispherical internal cavity 4 defined by the probe body 2. The target object of the ultrasound probe 1 is arranged in the hemispherical internal cavity 4. In medical applications, this target object is for example the top of a head or a breast. The hemispherical internal cavity 4 therefore has a sufficient volume to accommodate the target object. Typically, the hemispherical internal cavity 4 has a larger section with a diameter greater than 10 cm, and preferably greater than 20 cm.

[0019] The transducers 8 are at least capable of converting electrical energy into acoustic energy, enabling them to emit ultrasound towards the hemispherical internal cavity 4 in response to an electrical excitation signal. Preferably, the transducers 8 are also capable of converting acoustic energy into electrical energy, enabling them to provide an electrical measurement signal in response to the reception of ultrasonic waves from the hemispherical internal cavity 4, for example reflected by the target object.

[0020] The transducers 8 can be produced using different technologies. In particular, the transducers 8 can be piezoelectric transducers, micromachined membrane transducers. In general, the transducers 8 have an emission / reception face forming a part of the hemispherical emission / reception interface of the ultrasonic probe, this emission / reception face constituting the active part emitting or receiving the ultrasonic waves.

[0021] The transducers 8 are carried by modules 10 which form the probe body. The probe body 2 comprises at least six modules. Each module is removable and can be individually removed from the probe body 2. Each module 10 carries at least 2 transducers 8, and preferably more than 10 transducers 8, and even more preferably more than 50 transducers. In one example, each module is provided with 256 transducers. Preferably, the modules 10 carry the same number of transducers 8.

[0022] Connectors may be provided on each module 10, on the outer face of said module 10, which is intended to be arranged on the side opposite the hemispherical internal cavity 4. Electrical equipment such as pre-amplification modules may then be connected to the transducers 8. Preferably, each module 10 is provided with a connection interface grouping connections of each of the transducers 8 carried by said module. Typically, a cable with as many channels as there are transducers 8, for example according to a 256-channel connection, makes it possible to connect all of the transducers in a single operation.

[0023] These modules 10 are adjacent to each other, and therefore partition a hemispherical surface 12 corresponding to the probe body 2. Each module 10 corresponds to a partition of the same surface area of ​​the hemispherical surface 12. [Fig.2a] and [Fig.2b] are exploded views showing the composition of the probe body 2 by modules 10 according to two preferred embodiments. In a first preferred embodiment illustrated by [Fig.2a], the hemispherical surface is partitioned into 12 modules 10a, and in a second preferred embodiment illustrated by [Fig.2b], the hemispherical surface is partitioned into 6 modules 10b. The modules 10b of this second preferred embodiment correspond to two-by-two meetings of modules 10a of the first preferred embodiment.In this second embodiment, the spherical quadrilaterals defined by the partition of the hemispherical surface 12 by the modules 10 have two lengths at least 1.5 times longer than their two widths. An advantage of this second embodiment is that, due to the smaller number of modules 10, there are fewer edges 20 delimiting the periphery of each module. More precisely, this amounts, for each module 10b of the second preferred embodiment, to removing an edge 20 between the two modules 10a of the first preferred embodiment. Since this removed edge 20 can be replaced by transducers on the surface thus freed, the active emission / reception surface can be increased. However, the advantages linked to the modular aspect of the ultrasonic probe 1 are reduced. In particular, the replacement of a module 10 corresponds to a replacement of a larger part of the ultrasonic probe 1.

[0024] The modules 10 are identical at least in terms of shape, and more precisely at least with regard to their partition of hemispherical surface 12. In fact, each module 10 corresponds to a partition of the same surface area of ​​a hemispherical surface 12. The modules 10 can thus be interchanged with each other by means of a possible rotation. The modules 10 are organized adjacent to each other according to a hemispherical surface 12, which can be the hemispherical transmission / reception interface 6, that is to say the transmission surface of the transducers 8, or any other hemispherical surface corresponding to an expansion of the hemispherical transmission / reception interface 6, that is to say sharing the same center as the hemispherical transmission / reception interface 6 but with any radius.

[0025] Each module 10 defines a spherical quadrilateral on said hemispherical surface 12. A spherical quadrilateral is understood to mean a four-sided figure on a spherical surface, formed by four vertices connected by great circle arcs of a sphere. A great circle can be defined as a circle drawn on the surface of a sphere which has the same diameter as it or as the intersection between a sphere and a plane passing through the center of this sphere.

[0026] The modules 10 are organized so that each vertex of a spherical quadrilateral of a module 10 is adjacent to less than four vertices of spherical quadrilaterals of other modules 10. Thus, a corner of a module 10, corresponding to a vertex of the spherical quadrilateral of said module 10, is adjacent only with a maximum of three other corners of other modules 10. For example, in the configuration with 12 modules 10, only four modules 10 meet at the vertex S of the hemispherical surface 12. This characteristic makes it possible to avoid angles that are too acute for the corners of the modules 10, and facilitates the assembly of the modules 10.

[0027] By definition, the edges of the spherical quadrilateral of each module 10 are great circle arcs of the hemispherical surface 12. Figures 3a and 3b show an example of partitioning a hemispherical surface 12 into modules 10 of a body of an ultrasonic probe 1 showing the great circle arcs involved in said partitioning. The solid lines show the limits of each spherical quadrilateral, formed by parts of great circle arcs 14, while the dotted lines show the other parts of great circle arcs 16 which do not correspond to limits of spherical quadrilaterals and are therefore shown for purely explanatory purposes.

[0028] In this partitioning into twelve modules 10, the modules 10 partition the hemispherical surface according to arcs of great circles obtained by rotation of 45° along three perpendicular axes. More precisely, since the hemisphere is a portion of a sphere delimited by a cutting plane passing through the center of the sphere, the base 18 of the hemispherical surface can be defined as the disk defined by this plane and said hemispherical surface. The three axes x, y, z, are defined in a reference frame centered on the center of the base 18, that is to say the center of the sphere. Two axes x, y among the three axes define the cutting plane, while the third axis z is perpendicular to the base 18, connecting the center O of the base 18 to the vertex S of the hemispherical surface 12 which is opposite said center O.

[0029] More concretely, starting from an original great circle arc running through a semicircle and with one end at the top of the hemispherical surface 12, we obtain the great circle arcs used in the partitioning by rotations of +45° and -45° around each of the three axes, and at least another +45° or -45° (i.e. +90° or -90° of the original great circle arc) around the third axis z perpendicular to the cutting plane. We could possibly complete the description of this partitioning by two rotations of +90° and -90° of the original great circle arc around one of the two axes (x, y) defining the cutting plane to find the edge of the hemispherical surface 12, but by definition the hemispherical surface is already delimited by a great circle.

[0030] Thanks to these arcs of great circles, the limits of the modules 10 can be defined to form spherical quadrilaterals. Preferably, the body 2 of the ultrasonic probe 1 comprises exactly twelve modules 10, as in figures 1a, 2a, 3a, and 3b, or exactly six modules 10, as in [Fig.2b]. In the configuration with 12 modules 10, the great circle arcs define spherical triangles between them, and the spherical quadrilateral of each module 10 is formed by the union of two spherical triangles by their largest common side. As a result, the spherical quadrilateral of each module 10 is crossed diagonally by a part of a great circle arc which does not delimit an edge of module 10, represented by dashes in figures 3a and 3b. In the configuration with six modules 10, each module 10 corresponds to the union of two modules 10 of the configuration with twelve modules 10, and therefore corresponds to the union of four spherical triangles.

[0031] With this partitioning, the modules 10 have strictly identical contours, the same surface area, and can therefore be interchanged by means of a possible rotation. It is therefore sufficient to manufacture, for example by machining, the required number of identical modules 10 (for example 12 or 6 modules 10), then to assemble them. For example, the body 2 of the ultrasonic probe can comprise a frame on which the modules are mounted. It is also possible for each module to have a mounting structure which is capable of being assembled with mounting structures of other modules, as in the examples of figures 1a, 2a and 2b, where each module 10 is surrounded by edges 20 which take the form of a spherical quadrilateral. During assembly, the modules 10 are juxtaposed edge to edge, as in figures 1a and 4, and the edges of two adjacent modules 10 are fixed to each other.

[0032] The modules 10 may be mounted by any mounting means, such as for example with glue to fix the modules together or fix the modules to the frame. Preferably, however, reversible fixing members are used, such as for example screws. Gaskets may be put in place between the modules 10. The frame and the mounting means are preferably accessible from the outside of the ultrasonic probe 1 (as opposed to the hemispherical internal cavity), i.e. the convex side of the probe body 2.

[0033] The presence of the modules 10 in the form of spherical quadrilaterals of the same surface area greatly simplifies manufacturing compared to configurations where each module 10 must have its own shape. In addition, the repair of such an ultrasonic probe 1 is greatly facilitated. In the event of failure or defects in transducers 8, it is sufficient to change the module 10 carrying said defective transducers 8, without having to change the other modules 10 or the entire ultrasonic probe 1. In addition, since the modules 10 are interchangeable, it is sufficient to have a single spare module 10 to be able to replace any of the modules 10 of the ultrasonic probe 1.

[0034] The ultrasonic transducers 8 can be distributed on the transmitting / receiving face of each module 10 in several ways. For example, the transducers 8 can be distributed on a transmitting / receiving face according to an aperiodic network, for example randomly or according to an aperiodic pattern such as a Voronoi tiling. [Fig. 4] thus shows an example of an ultrasonic probe 1 with 12 modules as in [Fig. 1a]. However, in this example, the transducers are distributed randomly on the surface of each module, as visible by the distribution of their rear faces 9 in [Fig. 4]. It is also possible to provide a regular distribution of the ultrasonic transducers 8 on the modules 10, the ultrasonic transducers thus being able to form an array.

[0035] Furthermore, the ultrasonic transducers 8 may be of various shapes, such as for example corresponding to discs of the same surface area. However, any area of ​​the emission / reception interface 6 not constituted by the active face of a transducer 8 results in a limitation of the maximum power and / or a lower sensitivity, which results in a lower quality of the images obtained from the reflected waves. For example, in the case of photoacoustic imaging, the image quality is strongly linked to the surface coverage or filling rate, that is to say to the ratio between the active emission / reception surface and the surface area of ​​the emission / reception interface. It is therefore preferred to maximize the filling of the emission / reception interface 6 by the active faces of the ultrasonic transducers 8 in order to achieve at least 50% filling, and preferably at least 75% filling.For this purpose, it may be preferable, depending on the applications, to use transducers 8 having active faces of polygonal shape whose juxtaposition leaves no or few holes, such as for example quadrilaterals, in particular spherical quadrilaterals. Similarly, it may be preferable, depending on the applications, to use a distribution of the ultrasonic transducers 8 on the transmission / reception interface which maximizes the filling rate.

[0036] Advantageously, the ultrasonic transducers of a module 10 can each define a spherical quadrilateral on the hemispherical surface 12, with the edges of the quadrilateral of each ultrasonic transducer being great circle arcs of the hemispherical surface 12. Advantageously, such ultrasonic transducers 8 are juxtaposed edge to edge.

[0037] [Fig. 5] shows a preferred configuration for organizing the transducers 8 on the modules 10, in this case on four spherical quadrilaterals 22 corresponding to the four modules adjacent to the vertex S of the hemispherical surface 12. The ultrasonic transducers 8 are distributed on the emission / reception face according to a network organized according to a plurality of arcs of first large circles 24 and arcs of second large circles 26 of the hemispherical emission / reception interface 6. first large circles 24 pass through a first common point A, the second large circles pass through a second common point B, the first common point A and the second common point B being arranged on an edge 28 of the hemispherical transmission / reception interface 6 and separated by a quarter circle (90°) on said edge 28. In doing so, a regular distribution of the ultrasonic transducers 8 is obtained on the spherical quadrilateral of each module. In order to maximize the filling rate, the arcs of first large circles 24 and the arcs of second large circles 26 can delimit the ultrasonic transducers 8, the ultrasonic transducers 8 then partitioning the surface of the module 10 according to said arcs of first large circles 24 and second large circles 26.

[0038] It is possible, as illustrated, for the first large circles 22 to have a regular angular spacing between them, and / or for the second large circles 24 to have a regular angular spacing between them. Of course, this regular spacing is chosen as a function of the number of transducers 8 per module 10 that it is desired to obtain. To limit the surface area differences between ultrasonic transducers, it is possible to choose an angular spacing which is a sub-multiple of the angular spacing of the large circle arcs defining the shapes of the modules 10.

[0039] This approach is however not optimal insofar as all the transducers do not then have the same surface area, and this heterogeneity of the surfaces can be detrimental to the homogeneity of the emissions or reception of the waves. It is possible to choose a partitioning of the surface of a module 10 by seeking to minimize the surface differences, for example by positioning the arcs of first large circles 24 (resp. the arcs of second large circles 26) to define columns (resp. rows) of the same surface area. This partitioning can be carried out iteratively, for example by placing each large circle arc 24, 26 on a surface so that it cuts said surface into two surfaces of the same surface area, and starting again until all the large circle arcs 24, 26 have been placed. It is also possible to analytically determine the positioning of each large circle arc 24, 26 to obtain the same result.

[0040] When the great circle arcs 24, 26 thus delimit the ultrasonic transducers 8, the columns and rows of ultrasonic transducers 8 have the same surface area, thus minimizing the differences in surface areas between the ultrasonic transducers 8 of the same module 10. Typically, there is then a progressive angular spacing between two consecutive first great circle arcs 24, and / or between two consecutive second great circle arcs 26.

[0041] The invention is not limited to the embodiment described and shown in the attached figures. Modifications remain possible, in particular from the point of view of the constitution of the various technical characteristics or by substitution of equivalents. techniques, without departing from the scope of protection of the invention.

Claims

Claims

1. An ultrasonic probe (1) comprising a body with a hemispherical transmission / reception interface (6) covered with ultrasonic transducers (8) configured to emit ultrasonic waves into a hemispherical internal cavity (4) from the hemispherical transmission / reception interface (6), characterized in that the body of the probe (2) comprises at least six modules (10) partitioning a hemispherical surface (12) sharing a common center with the hemispherical transmission / reception interface (6), the modules (10) carrying the ultrasonic transducers (8) of which a transmission / reception face forms for each a part of the hemispherical transmission / reception interface (6) of the ultrasonic probe, each module (10) corresponding to a partition of the same surface area of ​​the hemispherical surface (12), and defining a spherical quadrilateral on said hemispherical surface (12),the edges of the spherical quadrilateral of each module (10) being great circle arcs of the hemispherical surface (12).,

2. An ultrasonic probe according to claim 1, wherein the modules (10) are identical at least in terms of shape.

3. An ultrasonic probe according to any preceding claim, wherein each vertex of a spherical quadrilateral of a module (10) is adjacent to less than four vertices of spherical quadrilaterals of other modules (10).

4. An ultrasonic probe according to any one of the preceding claims, wherein the modules (10) partition the hemispherical surface according to arcs of great circles obtained by rotation of 45° along three perpendicular axes in a reference frame centered on the center of the edge of the hemispherical surface (12).

5. An ultrasonic probe according to any preceding claim, wherein the body (2) of the ultrasonic probe (1) comprises exactly 6 modules or 12 modules (10).

6. An ultrasonic probe according to any preceding claim, wherein the ultrasonic transducers of a module (10) each define a spherical quadrilateral on the hemispherical surface (12), the edges of the quadrilateral of each ultrasonic transducer being great circle arcs of the hemispherical surface (12).

7. An ultrasonic probe according to any one of the preceding claims, wherein each module (10) comprises a transmitting / receiving face forming a part of the hemispherical transmitting / receiving interface (6), and the ultrasonic transducers (8) are distributed on said transmitting / receiving face according to a network organized according to a plurality of arcs of first large circles (24) and arcs of second large circles (26) of the hemispherical transmitting / receiving interface (6), the first large circles passing through a first common point (A), the second large circles passing through a second common point (B), the first and second common points being separated by a quarter circle of the hemispherical transmitting / receiving interface (6).

8. An ultrasonic probe according to the preceding claim, wherein the first large circles (24) have a regular angular spacing between them, and / or the second large circles (26) have a regular angular spacing between them, or wherein the columns of ultrasonic transducers have the same surface area and / or the rows of ultrasonic transducers have the same surface area.

9. An ultrasonic probe according to any preceding claim, wherein the body (2) further comprises a frame on which the modules (10) are mounted, and / or each module comprises a mounting structure capable of being assembled with mounting structures of other modules.

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