Scattered ionizing radiation detection assembly and detection and visualization system comprising said detection assembly.

Abstract

The invention relates to an assembly for detecting scattered ionizing rays comprising: - a filtering device (3) for ionizing rays configured to spatially filter the ionizing rays according to their direction of emission; and - an imager (4) assembled opposite the filtering device (3) so as to receive the ionizing rays filtered by the filtering device (3), the imager (4) being configured to produce a radiographic image from the ionizing rays filtered by the filtering device (3); the filtering device (3) comprising several blades, said blades comprising a material capable of absorbing the ionizing rays, the blades being oriented so as to move away from a center of the filtering device (3). Figure for abstract: Fig. 1

Description

Title of the invention: Scattered ionizing radiation detection assembly and detection and visualization system comprising said detection assembly.

[0001] The invention relates to an ionizing radiation detection assembly and to a detection and visualization system comprising said detection assembly.

[0002] The invention finds its application in various fields depending on the type of ionizing radiation. For example, the invention finds its application in X-ray imaging, used in particular in the medical sector, or in the monitoring of nuclear installations in which gamma ray fluxes are present.

[0003] In these fields of application, the ionizing rays emitted in certain directions may be at least partly scattered in other, non-targeted directions. Thus, the ionizing rays initially emitted in the direction of one or more areas are also found in other, initially non-targeted areas. This is the case, for example, during interventional radiology in which an X-ray generator sends X-rays to an area of the patient's body. Part of the X-rays directed towards the patient are absorbed by the latter and another part of these X-rays is scattered by the patient as well as by objects located nearby and which are affected by these rays. The scattered rays spread out in all directions. Medical personnel are then exposed to this scattered radiation, in particular when they participate in the surgical procedure.Scattered radiation absorbed by medical personnel during an intervention is not dangerous because the dose received is low, but repeated exposure during multiple interventions can be dangerous.

[0004] In this context, it may be desirable to detect ionizing rays, in particular ionizing rays emitted or diffused in certain directions. One objective may be in particular to better protect against ionizing rays and / or to protect surrounding equipment.

[0005] The invention aims to propose a detection assembly for detecting ionizing rays present in an environment. The invention aims in particular to propose a detection assembly capable of detecting ionizing rays arriving in an area in given directions.

[0006] For this purpose, it proposes a detection assembly comprising: - an ionizing ray filtering device configured to spatially filter the ionizing rays according to their emission direction; and - an imager assembled opposite the filtering device so as to receive the ionizing rays filtered by the filtering device, the imager being configured to produce a radiographic image from the ionizing rays filtered by the filtering device. The filtering device comprises a plurality of blades, said blades comprising a material capable of absorbing ionizing rays, the blades being oriented so as to move away from a center of the filtering device.

[0007] The filtering device makes it possible, by its configuration in blades comprising an absorbent material and having particular orientations, to form a radiological image on the imager which only sees the ionizing rays arriving in certain directions. The filtering device eliminates (or absorbs) the ionizing rays arriving in a direction normal to a plane of the imager and allows the ionizing rays to pass in other directions which thus arrive on the imager.

[0008] Furthermore, the invention makes it possible to detect radiation over a relatively wide field. Indeed, the orientation of the blades moving away from the center of the filtering device, i.e. towards the outside of the filtering device, makes it possible to detect ionizing rays over a wide angle.

[0009] Particularly convenient preferred features of the detection assembly according to the invention are presented below.

[0010] The blades comprise a first series of blades and a second series of blades, the first series of blades comprising first blades following one another in a first direction, the second series of blades comprising second blades following one another in a second direction, the first direction and the second direction being orthogonal to each other, the first blades being oriented so as to move away from the center of the filtering device, the second blades being oriented so as to move away from the center of the filtering device.

[0011] At least two of the first blades are not parallel to each other and at least two of the second blades are not parallel to each other.

[0012] Spaces separate the blades from each other.

[0013] The imager is curved.

[0014] The imager has a half-spherical shape.

[0015] The imager is flat.

[0016] The filtering device and the imager have the same general shape.

[0017] Ionizing rays are X-rays or gamma rays.

[0018] According to another aspect, the invention also relates to a detection and visualization system comprising: - a detection assembly having the preceding characteristics; - an optical camera having the same field of vision as the imager, the optical camera being configured to produce an optical image; and - a reading and display device connected to the imager and to the camera, the reading and display device being configured to read the image received from the imager and the optical image received from the camera, superimpose the radiographic image and the optical image, and display the superposition of the radiographic image with the optical image.

[0019] Other features and advantages of the invention will become apparent in the description below with reference to the appended drawings, given by way of non-limiting example: - [Fig.l] represents a visualization detection system comprising a detection assembly according to an embodiment of the invention; - [Fig.2] represents the detection assembly of [Fig.l] with an optical camera; - [Fig.3] represents a filtering device of the detection assembly according to a first embodiment; - [Fig.4] represents the filtering device according to a second embodiment; and - [Fig.5] represents the detection assembly according to another embodiment of the invention.

[0020] [Fig.l] schematically represents a detection and visualization system 2 according to an exemplary embodiment of the invention.

[0021] The detection and visualization system 2 comprises a detection assembly 1, an optical camera 5 and a reading and display device 6.

[0022] The detection assembly 1 comprises a filtering device 3 for ionizing rays and an imager 4.

[0023] The filtering device 3 is configured to filter ionizing rays.

[0024] The nature of the ionizing rays varies depending on the application of the invention. Ionizing rays can be, for example, X-rays or gamma rays.

[0025] For a medical application, the ionizing rays may be X-rays. In an interventional radiology situation, the filtered X-rays typically come from the scattered rays when a patient receives rays from the X-ray generator. In particular, the filtered X-rays come from the “primary” scattered rays, i.e., scattered by the patient receiving rays emitted by an X-ray generator as well as by objects in the vicinity that are affected by the rays sent by the X-ray generator. The filtered X-rays may also be “secondary” scattered X-rays, i.e., resulting from the scattering by objects or personnel nearby, X-rays emitted by “primary” scattering.

[0026] For a nuclear application, the ionizing rays may be gamma rays used in a nuclear installation.

[0027] The filtering device 3 is assembled opposite the imager 4, as shown schematically in Figures 1 and 2.

[0028] Preferably, the distance separating the filtering device 3 and the imager 4 is small. Preferably, the distance separating the filtering device 3 and the imager 4 is less than 30 cm. This allows good detection of ionizing rays even when their flux is low.

[0029] The filtering device 3 is here fixed to the imager 4.

[0030] The filtering device 3 and the imager 4 have the same general shape. part or surface of the filtering device 3 assembled to the imager 4 has the same dimensions as the imager 4. The imager 4 has, for example, a generally rectangular shape. The filtering device 3 also has rectangular contours.

[0031] The imager 4 is planar in the embodiment of Figures 1 and 2. The filtering device 3 is also planar. The imager 4 and the filtering device 3 have a square shape in [Fig.l]. For example, the imager 4 and the filtering device 3 each have a square shape with a side of 20 cm.

[0032] The filtering device 3 and the imager 4 are parallel to each other.

[0033] The imager 4 is configured to produce an X-ray image from the ionizing rays filtered by the filtering device 3.

[0034] The imager 4 is for example a traditional X-ray detector. The imager 4 comprises in particular a sensor. The sensor is for example produced on a first substrate. The first substrate comprises a set of pixels organized in a matrix according to rows and columns. The matrix can comprise any number of rows and columns thus forming pixels. The matrix forms a geographical area on the first substrate. All of the pixels are configured so as to generate signals as a function of radiation arriving on the imager 4.

[0035] The pixels are sensitive to X-rays and deliver an electrical signal (in particular an electrical charge) whose level is a function of the intensity of the X-rays. In other words, the pixels comprise a photosensitive element, or photodetector, which may for example be a photodiode, a photoresistor or a phototransistor. The electrical signals from the different pixels are collected by reading circuits of the imager 4 during a reading phase of the matrix and then digitized so as to be able to be processed and stored to form the radiographic image.

[0036] Photosensitive elements make it possible to detect visible or near-visible electromagnetic radiation. These elements are not, or only slightly, sensitive to the radiation incident on the detector. A radiation converter called a scintillator is then frequently used, which converts the incident radiation, for example X-rays, into radiation in a wavelength band to which the photosensitive elements present in the pixels are sensitive. An alternative consists of making the photosensitive element in another material carrying out the direct conversion of the X-rays into electrical charges. This is the case, for example, of matrices in which a first pixelated substrate made of Cadmium Telluride (CdTe) is connected pixel by pixel to a CMOS reading circuit which therefore no longer has the detection function.

[0037] The imager 4 is preferably very sensitive and low in noise. This is conventionally expressed by the value of the NED of the detector ("Noise Equivalent Dose", the dose whose X-ray noise is equal to the electronic noise of the imager 4). For example, the signal received by the imager 4 in the case of an aperture of 1 cm2 to 20 cm2, and an X-ray dose sent to the patient by an X-ray source of intensity 10 mAs located 1 m from the patient, with an energy of 80 kV to 120 kV, could be only 0.01 to 0.05 nGy (nanoGray), which is very little. The imager 4 therefore has the capacity to produce readable images with doses of this order of magnitude, and its NED is typically less than or equal to 0.01 nGy.If the NED of imager 4 is higher, the images from imager 4 are averaged in time (temporal averaging, for example of 100 successive images) and / or in space (spatial averaging, for example by blocks of 10x10 pixels), which limits the temporal and / or spatial resolution, but brings the NED to the desired level.

[0038] The imager 4 can alternatively be a scintillator crystal. This is in particular a thallium-doped sodium iodide crystal: NaI (Tl). The sodium iodide crystal has the property of stopping gamma photons and converting part of the deposited energy into detected light scintillations from the photomultipliers. The photomultipliers cover the back of the scintillator. Each photomultiplier converts the light photons into an electrical signal. By positioning the photomultipliers in an array, the position and energy of the gamma ray that interacted in the crystal are determined.

[0039] According to another exemplary embodiment, the imager 4 may be a 4 gamma imager based on semiconductors, for example based on Cadmium-Zinc-Telluride (CdZnTe). This type of imager 4 is more precise in measuring the energy and position of the gamma rays.

[0040] The filtering device 3 comprises a material capable of absorbing ionizing rays.

[0041] In the case of X-rays, the material capable of absorbing the rays is, for example, lead, copper or tungsten. Copper has the advantage of being cheap, rigid and does not present a danger to the environment.

[0042] In the case of gamma rays, the material capable of absorbing the rays is, for example, lead or tungsten.

[0043] The filtering device 3 shown diagrammatically in [Fig.l] according to one embodiment, is shown individually and from different viewing angles in [Fig.3].

[0044] The filtering device 3 comprises several blades 300, 301 (shown in FIGS. 4, 5). The other figures represent the filtering device 3 in a very schematic manner.

[0045] The blades 300, 301 comprise or are made of a material capable of absorbing ionizing rays (for example lead, copper or tungsten). The blades 300, 301 are oriented so as to absorb the ionizing rays in several directions.

[0046] Each blade has a rectangular shape. Each blade thus has a longitudinal dimension or length, a lateral dimension or width, and a transverse dimension or thickness.

[0047] The blades 300, 301 are here separated by spaces 302. In other words, a void separates the adjacent blades 300, 301 from each other.

[0048] According to an alternative embodiment, the blades 300, 301 are not separated by an empty space. The filtering device 3 comprises portions of material arranged between the blades 300, 301. The portions of material are made with a material transparent to ionizing rays. Preferably, the portions of material are rigid. This makes it possible to hold the blades 300, 301 firmly in place. When the ionizing rays are X-rays, the portions of material are, for example, portions of polyurethane foam. For gamma rays, the portions of material may be made of a plastic material transparent to gamma rays which preferably does not degrade under the effect of this radiation. For example, the portions of material are made of polyimide.

[0049] The blades 300, 301 comprise a first series of blades and a second series of blades. The first series of blades comprises first blades 300 following one another in a first direction DI. The second series of blades comprises second blades 301 following one another in a second direction D2. The first direction DI and the second direction D2 are distinct, here orthogonal to each other.

[0050] A space 302 here separates each of the first blades 300. Similarly, a space 302 here separates each of the second blades 301.

[0051] The blades 300, 301 are oriented so as to move away from a center 303 of the filtering device 3. In particular, the first blades 300 are oriented so as to move away from the center 303 of the filtering device 3 and the second blades 301 are oriented so as to move away from the center 303 of the filtering device 3. In other words, the blades 300, 301 are oriented towards the outside of the filtering device 3. The blades 300, 301 thus configured, when the filtering device 3 is used with a radiological assembly, diverge from an ionizing ray generator.

[0052] The blades 300, 301 are oriented so as to filter the ionizing rays in several directions. The blades 300, 301 are oriented according to a non-zero orientation angle relative to the plane generated by the first direction DI and the second direction D2.

[0053] The blades 300, 301 are each oriented according to a predefined orientation angle so that, for given blades 300, 301, the ionizing rays arriving in certain directions are blocked by said given blades 300, 301. Said given blades 300, 301 absorb the ionizing rays arriving in said directions. The ionizing rays arriving in a different direction pass.

[0054] When the filtering device 3 comprises spaces between the blades 300, 301, the ionizing rays pass when they arrive in the space between two blades 300, 301. In other words, the ionizing rays which pass are those which do not arrive on a blade. In other words, the ionizing rays arriving in a given direction are absorbed by the blades 300, 301 except in a given part of the filtering device 3 in which said ionizing rays pass between two blades 300, 301 and are placed on a given zone of the imager 4.

[0055] The operation of the filtering device 3 is similar when it comprises a material transparent to ionizing rays in place of the empty spaces 302 between the blades 300, 301.

[0056] Thanks to this configuration of the filtering device 3, each zone of the imager 4 only sees one direction of ionizing rays. The direction of ionizing rays seen by each zone of the imager 4 depends at least on the orientation of the blades 300, 301 of the filtering device 3.

[0057] The orientation angle is modified along the filtering device 3. Several blades 300, 301 may have the same orientation angle. The orientation angles of the blades 300, 301 vary so as to absorb the ionizing rays in certain directions and allow them to pass in other directions.

[0058] Preferably, at least two of the first blades 300 are not parallel to each other and at least two of the second blades 301 are not parallel to each other. In other words, at least two of the first blades 300 have different orientation angles from each other and at least two of the second blades 301 have different orientation angles from each other.

[0059] The filtering device 3 as described above forms a lens for ionizing rays. The filtering device 3, by the use of several radio- opaque "sections" the ionizing rays. The final radiographic image obtained by the imager 4 is an assembly of the images obtained by the reception of the ionizing rays "sectioned" by the filtering device 3. The assembly of the images is carried out in the manner of a mosaic. The assembly of the images is similar to that made by insects with compound eyes.

[0060] The number of blades 300, 301, their thickness and their orientation define the filtered image. The number of blades 300, 301, their thickness and their orientation are predefined and sized according to the need. These parameters define the gap (or even the space when there is one) between the blades 300, 301.

[0061] The blades 300, 301 of the filtering device 3 have a thickness of between 0.1 mm and 5 mm, preferably approximately 1 mm.

[0062] The width of each blade is between 1 mm and 10 cm, preferably equal to 1 cm.

[0063] The length of each blade depends on the size of the imager 4 used. The length of each blade is less than or equal to the length of the imager 4, and preferably equal to the length of the imager 4. The length of each blade is between 1 cm and 50 cm, preferably equal to 20 cm.

[0064] The orientation angle of the blades 300, 301 is between -90° and 90, preferably between -60° and 60°.

[0065] The number of blades 300, 301 is between 10 and 1000, preferably approximately 100.

[0066] The filtering device 3, flat in the embodiments of Figures 1 to 4, has a depth, i.e. a total thickness, of between 1 and 10 cm. The filtering device 3 is thus very compact.

[0067] The filtering device 3 can be made in one piece, as is the case in [Fig.3],

[0068] In a variant shown in [Fig. 4], the filtering device 3 is made in two parts. The filtering device 3 comprises a first part 304 and a second part 305. The first part 304 comprises the first series of first blades. The second part 305 comprises the second series of second blades 301. The blades are each oriented according to a predefined orientation angle, similarly to the embodiment of [Fig. 3].

[0069] The first part 304 and the second part 305 can be superimposed as in [Fig.4].

[0070] In a variant not shown, the first part 304 and the second part 305 can be intersected.

[0071] The production of the filtering device 3 in two parts is more economical than the production in one piece.

[0072] The filtering device 3 can be manufactured by 3D printing, by molding, or by any other means allowing the desired geometry and shapes to be obtained.

[0073] The filtering device 3 is preferably arranged at a distance from the area to be imaged of between 10 cm and 5 m, preferably of the order of 2 m. The smaller the distance, the better the quality of the radiographic image obtained.

[0074] However, it should be noted that in the case of the X-ray imager 4, the signal received by a pixel does not decrease with the distance between the imager 4 and the area to be imaged, provided that the area to be imaged is large enough and still covers the pixel. Indeed, the X-ray signal decreases as 1 / R2, R being the distance between the imager and the area to be imaged, but the surface area of the area that is imaged in a pixel increases as R2. The two effects compensate each other, and the signal is constant.

[0075] The imager 4 may have a different shape, for example the imager 4 may be curved. The imager 4 may have a dome or half-sphere shape, as illustrated in [Fig.5]. The filtering device 3 has a similar shape, here a dome.

[0076] The imager 4 and the filtering device 3 have the same characteristics as previously described for the imager 4 and the 3-plane filtering device.

[0077] In particular, the filtering device 3 comprises several blades 300, 301 extending away from the center 303 of the filtering device 3.

[0078] The filtering device 3 is also here fixed to the imager 4.

[0079] The dome or semi-spherical shape allows the imager 4 to capture more radiation compared to the plane shape.

[0080] The dome may typically have a diameter of between 10 cm and 40 cm, for example 20 cm. The height may be between 5 cm and 20 cm, for example 10 cm.

[0081] The radiographic image obtained depends, as explained above, on the configuration of the filtering device 3. The radiographic image is also a function of the number of pixels or photomultipliers of the imager 4 located opposite the spaces 302 between the plates 300, 301 or the portions made of material transparent to radiation. Several pixels or photomultipliers are preferably opposite each space between the plates 300, 301, or each portion made of material transparent to X-ray radiation.

[0082] Each pixel or photomultiplier has dimensions of the order of a millimeter, or even a few millimeters. These dimensions are sufficient for the intended applications which do not require high image resolution.

[0083] The optical camera 5, visible in figures 1, 2 and 5, is configured to produce an optical or visible image. The camera 5 comprises a lens 500 and a CCD or CMOS photographic sensor 501.

[0084] The imager 4 and the lens 500 of the optical camera 5 are directed towards the same point or the same area to be captured or imaged. The optical camera 5 has substantially the same field of vision as the imager 4. For example, the imager 4 and the lens 500 of the camera 5 can be directed towards the areas or people exposed to ionizing rays.

[0085] The optical camera 5 is arranged in a plane parallel to the imager 4. The optical camera 5 may be arranged above the imager 4 ([Fig.l]). The optical camera 5 may be arranged at the center or focal point of the dome ([Fig.5]) or other curved shape.

[0086] The reading and display device 6 is connected to the imager 4 and to the camera 5. The reading and display device 6 is configured to read the radiographic image received from the imager 4 and the optical image received from the camera 5, superimpose the radiographic image and the optical image, and display the superposition of the radiographic image with the optical image.

[0087] The reading and display device 6 comprises means of connection to the imager 4 and to the optical camera 5. The connection means are for example connectors or wireless connection means.

[0088] The reading and display device 6 comprises an image reading and processing system. The reading and display device 6 may comprise a computer for image processing. The image processing may be carried out by software allowing the combination of the optical image and the radiographic image.

[0089] The reading and display device 6 further comprises a display 600, such as a monitor or screen for displaying the superposition of the radiographic image and the optical image. The display 600 is connected to the image reading and processing system.

[0090] The superposition of the radiographic image with the optical image shows the ionizing rays by displaying them on the optical image. In other words, the scattered ionizing rays can be visualized with the location where they are scattered thanks to the superposition with the optical image.

[0091] The ionizing rays may be displayed in a different color from the optical image. The optical image may be, for example, in black and white, and the ionizing rays in another color.

[0092] Information of interest may also be displayed, such as the intensity of the ionizing rays. Numerical values of the intensity may be displayed and / or the ionizing rays may be displayed in different colors depending on their intensity.

[0093] The areas diffusing the ionizing rays, as well as possibly other information such as their intensity, are displayed superimposed on the optical image. The user can see this information appear in real time on the display 600. This could, for example, encourage them (especially medical personnel) to protect themselves from ionising rays.

[0094] The detection assembly according to the invention allows, by a simple structure and configuration, to spatially filter the ionizing rays according to their direction of emission. By its configuration diverging from the center of the filtering device, the latter allows the detection assembly to have a large field or large angle to capture the ionizing rays on the imager 4.

[0095] The detection and visualization system makes it possible to detect and visualize the areas of diffusion of ionizing rays so as to protect oneself from them, for example. The display can be done in real time in order to provide live information on the diffusion of ionizing rays.

Claims

Claims

1. Scattered ray detection assembly comprising: - an X-ray filtering device (3) configured to spatially filter the X-rays according to their emission direction; and - an imager (4) assembled opposite the filtering device (3) so as to receive the X-rays filtered by the filtering device (3), the imager (4) being configured to produce a radiographic image from the X-rays filtered by the filtering device (3);the filtering device (3) comprising a plurality of blades (300, 301), said blades (300, 301) comprising a material capable of absorbing X-rays, the blades (300, 301) comprising a first series of blades and a second series of blades, the first series of blades comprising first blades (300) following one another in a first direction (D1), the second series of blades comprising second blades (301) following one another in a second direction (D2), the first direction (D1) and the second direction (D2) being orthogonal to each other, the first blades (300) being oriented so as to move away from a center (303) of the filtering device (3) in the direction going from the imager (4) towards the filtering device (3), the second blades (301) being oriented so as to move away from the center (303) of the filtering device (3) in the direction going from the imager (4) to the filtering device (3).;

2. The detection assembly of claim 1, wherein at least two of the first blades (300) are not parallel to each other and at least two of the second blades (301) are not parallel to each other.

3. A detection assembly according to claim 1 or claim 2, wherein spaces (302) separate the blades (300, 301) from each other.

4. Detection assembly according to one of claims 1 to 3, in which the imager (4) is curved.

5. Detection assembly according to one of claims 1 to 4, in which the imager (4) has a semi-spherical shape.

6. Detection assembly according to one of claims 1 to 3, in which the imager (4) is flat.

7. Detection assembly according to one of claims 1 to 6, in which the filtering device (3) and the imager (4) have the same general shape.

8. Detection and visualization system comprising: - a detection assembly (1) according to one of claims 1 to 7; - an optical camera (5) having the same field of vision as the imager (4), the optical camera (5) being configured to produce an optical image; and - a reading and display device (6) connected to the imager (4) and to the camera (5), the reading and display device (6) being configured to read the image received from the imager (4) and the optical image received from the camera (5), superimpose the radiographic image and the optical image, and display the superposition of the radiographic image with the optical image.

Images