• 专利附录
  • 专利说明
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    • 专利摘要:
    The invention relates to the field of object analysis by X-ray diffraction spectrometry. A first object of the invention is a collimator whose shape makes it possible to simultaneously analyze different parts of an object. For this, the collimator comprises channels inclined relative to an axis, said central axis of the collimator, so that different channels address different elementary volumes distributed in the object. A second object of the invention is a device for analyzing an object by X-ray diffraction spectrometry, using this collimator. A third object of the invention is a method for analyzing an object using such a device. The object may for example be a biological tissue that it is desired to characterize non-invasively and non-destructively.
    公开号:FR3043247A1
    申请号:FR1560443
    申请日:2015-10-30
    公开日:2017-05-05
    发明作者:Fanny Marticke；Guillaume Montemont；Caroline Paulus
    申请人:Commissariat a lEnergie Atomique CEA；Commissariat a lEnergie Atomique et aux Energies Alternatives CEA；
    IPC主号:
    专利说明:

    Collimator for X-ray diffraction spectrometry. Associated device and its use
    Description
    TECHNICAL AREA
    The technical field of the invention is the characterization of an object by a spectrometric analysis of an ionizing radiation diffracted by said object. The invention is equally applicable to biological tissue analysis, for diagnostic purposes, as well as to non-destructive testing in the industrial field or for safety-related applications.
    PRIOR ART
    X-ray diffraction spectrometry, better known by the acronym EDXRD (Energy Dispersive X Ray Diffraction) is a non-destructive analysis technique frequently used for the identification of materials composing an object. This technique is based on the elastic diffusion of ionizing electromagnetic radiation, also called Rayleigh scattering. It has already been applied in the control of nuclear material, in the detection of explosives or other illicit substances. In general, this technique consists in irradiating an object using a polyenergetic X-ray radiation and in determining the energy spectrum of the scattered radiation, by the object, at low angles, typically between 1 ° and 20 °, with respect to the trajectory of the X-radiation incident to the object. The analysis of this spectrum makes it possible to identify the materials constituting an object. Indeed, most materials have a specific spectral signature, depending on their atomic or molecular structure. The comparison of the measured scattering spectra with signatures of known materials makes it possible to go back to the composition of the object.
    In devices known to date, an irradiation source produces a polyenergetic X-ray propagating towards an object, a primary collimator or pre-collimator being disposed between the source and the object, so as to direct a radiation X finely collimated towards the object. A second collimator is then placed between the analyzed object and a detector, the latter being able to acquire an energy spectrum of the radiation scattered by the object. Different forms of this second collimator have been proposed. It can be: a simple opening made in a dense material, as described in the application WO2013098520; The sensitivity of the measurement is limited by the size of said aperture, the latter acting in the same way as a pinhole for optical applications. channels extending parallel to each other, as described in US Pat. No. 7,735,495 B2; this considerably limits the angular range addressed by the device. convergent channels all to the same point, as described in the publication Malden, "A CdZnTe array for detection of explosives in baggage by energy-dispersive X-ray diffraction signatures at multiple scatter angles", Nuclear Instruments and Method in Physics Research A ( 2000). This technique is sensitive, but requires a point-by-point scan of the examined object.
    Recent studies have shown that X-ray diffraction spectrometry is potentially useful in the field of medical diagnosis, in order to discriminate healthy tissue from a cancerous tumor. Studies have shown that the signature of a healthy tissue was different from the signature of a tumor. In mammography, for example, the publication Kidane, G et al "X-ray Scatter Signatures for Normal and Neoplastic Breast Weaves" Physics in Medicine and Biology, No. 44, 1999 pp 1791-1802, established a clear difference between spectra diffraction X obtained respectively on healthy tissues, fibroglandular tissues and a malignant tumor of carcinoma type. Healthy or fibroglandular tissues show a peak around 1.1 nm "1, while cancerous tissue shows a peak around 1.6 nm" 1. The unit nm "1 represents a transfer of momentum, which is obtained knowing the energy of the scattered radiation and its scattering angle, according to principles known and recalled below.
    However, the possibilities of application to living beings face difficulties related to the integrated dose and the duration of an examination. Indeed, at a time when the optimization of the dose received by a patient becomes a major concern, it is necessary to propose a method of analysis offering a compromise between the sensitivity and the integrated dose. In addition, the tissues analyzed can have a large volume, and it is necessary that the volume analyzed, in a single acquisition, be optimal, so as to limit as much as possible a scan around an organ to examine. The invention meets these requirements.
    SUMMARY OF THE INVENTION
    A first object of the invention is a collimator, intended to be interposed between an object and an ionizing electromagnetic radiation detector, the collimator extending, between a first end and a second end, around a central axis, the collimator having a plurality of channels, each channel being delimited by side walls, the collimator being such that: each channel has a median axis, extending, in the center of the channel, between said side walls delimiting said channel; the median axis of each channel forms an acute angle, called the collimation angle of the channel, with the central axis of the collimator; each channel is associated with a point, called the focal point, formed by an intersection between the median axis of said channel and said central axis of the collimator; the collimator being characterized in that it comprises at least two channels, whose collimation angles are different, the focal points respectively associated with these channels being different and spaced apart from each other along said central axis of the collimator.
    Such a collimator, when placed between an object irradiated with ionizing electromagnetic radiation, and a detector, makes it possible to transmit to the detector radiation emitted by the object, and in particular diffused radiation, at different angles. Moreover, the fact of having several different focal points allows the detection of radiation emitted by different parts of the object. When the emitted radiation is a scattering radiation, it allows to characterize simultaneously these different parts without having to move the collimator relative to the object.
    According to one embodiment, the collimator comprises a plurality of channels of the same collimation angle, said channels extending around the central axis of the collimator, the focal points of said channels being merged.
    At least one channel may have a cross section in a plane perpendicular to said central axis, said cross section forming all or part of a ring about the central axis. This cross section can form a ring around the central axis. The ring may be circular or polygonal.
    The collimator may include any of the following characteristics, taken separately or in technically feasible combinations.
    At least two focal points are spaced from each other, along said central axis of the collimator, by a distance greater than 2 cm or even 4 cm.
    The collimator channels define a plurality of focal points, for example between 2 and 20 different focal points.
    Each side wall delimiting a channel is made of a material whose atomic number is greater than 26.
    Each channel being delimited by a so-called proximal lateral wall and a so-called distal lateral wall, the proximal wall being closer to the central axis than the distal wall, each of these walls extending between the first end of the channel and the second end of the canal. Each of these walls can form a frustoconical surface defined: by a vertex, located on the central axis; And, at said second end, by a generator describing all or part of a ring.
    The collimator comprises a so-called base wall, extending around the central axis by describing a cylinder or a truncated cone, with a thickness greater than 5 mm. This base wall may be solid or have a hollow cavity, extending along a median axis coincident with the central axis of the collimator Each channel converges towards the central axis of the collimator.
    Another object of the invention is a device for analyzing an object, comprising: a source of irradiation, capable of producing an ionizing electromagnetic radiation propagating to a support capable of receiving an object; a first collimator disposed between the irradiation source and the support, the first collimator having an opening adapted to form a collimated incident beam propagating along an axis of propagation towards the support; a detector, comprising pixels, each pixel being adapted to detect ionizing electromagnetic radiation, and to form a spectrum thereof; a second collimator disposed between the support and the detector, the second collimator being able to selectively direct a radiation, in particular a scattering radiation, emitted by said object, held by the support, towards said detector, according to an angle of diffusion of said radiation emitted by the object; characterized in that said second collimator is a collimator as described in this application.
    Thus, each channel transmits to the detector radiation emitted by an elementary volume of the object, disposed on the support, said elementary volume extending around a focal point defined by said second collimator, according to a predetermined angular range.
    The device may include one of the following features, taken separately or in technically feasible combinations:
    The ionizing radiation emitted by the source is a poly-energy radiation, the source being for example an X-ray emitter tube.
    The second collimator is arranged so that its central axis is coaxial with the axis of propagation of the collimated incident beam.
    The detector extends in a plane, said detection plane, perpendicular to said central axis of the second collimator. Several pixels are then arranged at the same distance, called the radial distance, from said central axis of the second collimator.
    The detector is linked to a computer, such as a microprocessor, capable of subdividing each pixel of the detector into so-called virtual pixels.
    The combination of the characteristics mentioned in the four preceding paragraphs is preferred.
    The device may comprise an object to be analyzed, arranged on the support, such that at least one focal point, and preferably several focal points, defined by the second collimator, are placed in the object.
    A third object of the invention is a method for analyzing an object using a device as previously described, comprising the following steps: a) placing the object on the support of the device and irradiating the object with the aid of the irradiation source, so as to form a collimated incident beam propagating towards the object along an axis of propagation, the object being arranged in such a way that several focal points of the second collimator are placed in said object; b) with the aid of each pixel of the detector, detecting a radiation scattered by the object following its irradiation by said collimated incident beam and forming a spectrum representative of the energy distribution of said detected radiation; c) defining a plurality of groups of pixels, each pixel group receiving diffusion radiation from the same volume element of said object, said volume element being disposed along said propagation axis, two groups of different pixels receiving a plurality of groups of pixels; scattering radiation of two elements of different volumes; d) for each pixel group defined in the previous step, combining the spectrum acquired by each pixel, so as to establish a spectrum, said combined spectrum associated with said pixel group; e) using combined spectra respectively associated with different groups of pixels, determining a nature of the material constituting several volume elements of said object. The central axis of the second collimator is preferably coincident with the propagation axis of the collimated beam. The detector preferably extends perpendicular to the collimator axis, each pixel group comprising pixels situated at the same distance, called the radial distance, from said central axis of the collimator. The object can in particular be a biological tissue. The invention then makes it possible to characterize the nature of the tissue in a non-invasive manner.
    The direction of the collimated incident beam can be defined from a priori resulting from a prior inspection of the object. This preliminary inspection can be performed by X-ray or X-ray tomography or ultrasound or Magnetic Resonance Imaging. Other advantages and features will emerge more clearly from the following description of particular embodiments of the invention, given by way of non-limiting examples, and represented in the accompanying drawings described below.
    FIGURES
    FIG. 1A represents an example of a device for analyzing a material according to the invention. Fig. 1B shows a first collimator embodiment, in sectional view, of the device described in connection with Fig. 1A. The section is made along a plane parallel to the central axis of the collimator and passing through this axis. Figure IC shows a detail of an elementary volume of an object observed by a channel. Figure 1D shows the elementary volumes of an object associated with different channels, as well as a volume element associated with a pixel of the detector. Figure 1E shows an example of a detector. FIG. 1F represents an example of a spectrum of radiation emitted by an irradiation source. FIGS. 1H and 1H show sections of the first collimator embodiment, in a plane perpendicular to the central axis of the collimator.
    Fig. 2A shows a second collimator embodiment suitable for use in the device shown in Fig. 1A. Figures 2B and 2C show sectional views of this collimator, in a plane perpendicular to its central axis. Figure 2D shows a three-dimensional view of the collimator shown in Figure 2A. Figure 2E is a sectional view of the diagram of Figure 2D, the section being formed along a plane passing through the central axis of the collimator and parallel to this central axis.
    FIG. 3 represents a characterization of a collimator of geometry similar to the collimator shown in FIGS. 2A to 2E, and comprising 10 annular channels.
    FIG. 4 represents a characterization of a collimator of geometry similar to the collimator shown in FIGS. 2A to 2E, and comprising 10 annular channels, this collimator extending at a greater height than the collimator characterized in FIG.
    Figure 5 shows the main steps of a method for analyzing an object with a device as shown in Figure IA.
    DESCRIPTION OF PARTICULAR EMBODIMENTS
    Figure 1A shows an example of a device 1 for analyzing a material. An irradiation source 11 emits ionizing electromagnetic radiation 12 propagating towards an object 10, the composition of which it is desired to determine. The device comprises a first collimator, or pre-collimator 30, capable of collimating the radiation emitted by the irradiation source 11 to form a collimated incident beam 12c propagating along a propagation axis 12z towards the object. The device also comprises a detector 20, comprising pixels 20i, j, each pixel being able to detect a radiation 14 transmitted by the object irradiated by the collimated incident beam, this radiation being for example derived from an elastic scattering of the radiation forming the collimated incident beam 12c.
    The analysis device 1 comprises a second collimator 40, interposed between the object 10 and the detector 20. This collimator extends around an axis, said central axis 45. It is able to selectively direct towards the detector, a diffusion radiation 14i, 142, 143, 144, transmitted by the object 10, as a function of the angle θι, 02, 03, 04 of propagation of this radiation with respect to the central axis 45. The term Selectively means that the radiation transmitted to the detector depends on the angle at which it propagates and the part of the object from which it is emitted. This second collimator, designated by the term collimator in the rest of the text, is a key element of the invention and will be described more precisely later.
    The analysis device 1 is placed in a repository to which is attached an orthogonal reference X, Y, Z as shown in Figure IA. The object is arranged or maintained on a support 10s.
    The term ionizing electromagnetic radiation refers to electromagnetic radiation consisting of photons of energy greater than 1 keV, and preferably less than 5 MeV. The energy range of ionizing radiation can range from 1 keV to 2 MeV, but most often ranges from 1 keV to 150 keV or 300 keV. The ionizing radiation may be X or y radiation. Preferably, the source of ionizing radiation is poly-energetic, the incident radiation being emitted in a range of energy generally extending in the tens or even hundreds of keV range. These include an X-ray emitter tube.
    The radiation detector is a detector comprising pixels 20y arranged in a plane, called detection plane P20. The indices i, j denote the coordinates of each pixel in the detection plane. Pixels can extend along a line, but in general they extend in a two-dimensional regular matrix. In the examples described in this application, the detection plane extends along a plane X, Y perpendicular to the central axis 45 of the collimator, the latter being coincident with the propagation axis 12z of the collimated incident beam 12c. This is a preferred configuration.
    The irradiation source 11 is an X-ray tube with a tungsten anode, which is subjected to a voltage, generally between 40 and 150 kV that can be varied in order to change the energy range of the incident radiation 12 The detector 20 comprises 40 pixels along the X axis by 40 pixels along the Y axis, ie 1600 pixels, each pixel extending along an area of 2.5 * 2.5 mm 2, its thickness being 5 mm. The material constituting each pixel is a semiconductor, for example CdTe or CdZnTe or any other material able to perform spectrometric measurements, preferably at room temperature. It could also be a scintillator-type material, subject to sufficient energy resolution. The detector is resolved in energy, and each pixel makes it possible to obtain spectra according to energy channels of the order of 1 keV. The irradiation source 11 may comprise a metal screen, for example copper, so as to block the propagation, to the pre-collimator 30, of a radiation whose energy is less than 20 keV. When this screen is copper, its thickness is for example equal to 0.2 mm.
    The first collimator 30, or pre-collimator, comprises a block of dense material 31, able to absorb almost all of the radiation 12 emitted by the irradiation source 11. It comprises a thin aperture 32, extending along an axis , said propagation axis 12z, allowing the passage of a thin collimated beam 12c. By thin opening, we mean an opening whose diameter or the largest diagonal is less than 2 cm, or even 1 cm. In this example, the opening is a 1 mm diameter cylinder. The object 10 may be a living biological tissue, for example a body part of an animal or a human being. The device is then a medical imaging device. The body part may in particular be an organ in which following an initial examination, for example an X-ray or a CT scan, the presence of an abnormality, in particular a cancerous tumor, is suspected. This first examination also makes it possible to determine an approximate location of the anomaly in the tissue. The device 1 can then be implemented as a second indication, in order to characterize the nature of the tissues composing the organ, at the level of said anomaly as well as in its vicinity. The organ is in particular a body located at the periphery of the body, so as to allow easy analysis without being affected by the attenuation due to bones or other organs. It may in particular be a breast, a testicle, or an organ of the abdominal cavity. In other applications, the object may also be an industrial part or luggage, the device 1 then being used for non-destructive testing purposes.
    Each pixel 20jj constituting the radiation detector 20, comprises: a detector material capable of interacting with the photons of a radiation 14i, 14 2 ... 14n ... 14N transmitted by the object 10, through the second collimator 40, this material being of the scintillator type or, preferably, a semiconductor material compatible with use at room temperature, of the CdTe, CdZnTe type; an electronic circuit, capable of generating a signal whose amplitude A depends, and is preferably proportional, to an energy E deposited by each interacting photon in the detector material; a spectrometry circuit capable of establishing an energy spectrum, denoted Sj; signals detected during a time period, called the acquisition period.
    Thus, when the pixels are regularly arranged in a matrix arrangement, each pixel is capable of producing a spectrum Si; radiation 14 transmitted by the object according to this matrix arrangement.
    The term energy spectrum corresponds to a histogram of the amplitude A of the signals detected during a period of acquisition of the spectrum. A relation between the amplitude A of a signal and the energy E of a radiation can be obtained by an energy calibration function g such that E = g (A), according to principles known to the human being. job. An energy spectrum Sij can therefore take the form of a vector, each term of which Sij (E) represents a
    the amount of radiation detected by the pixel 20y in an energy range E ± -, with dE being the spectral width of a spectrum energy discretization step.
    The device also comprises a computing unit, or processor 22, for example a microprocessor, capable of processing each Si spectrum; measured by pixels 20i; In particular, the processor is a microprocessor connected to a programmable memory 23 in which is stored a sequence of instructions for performing the spectral processing operations and calculations described in this description. These instructions can be saved on a recording medium, readable by the processor, hard disk type, CDROM or other type of memory. The processor may be connected to a display unit 24, for example a screen.
    The collimator 40 has channels 42, extending around the central axis 45, and converging towards the latter. More precisely, each channel 42n is able to transmit a transmitted radiation 14n, according to a scattering angle θη belonging to a predetermined angular range Δθη, the radiation being transmitted by the object 10 to the detector 20.
    FIG. 1B shows a sectional view of the second collimator 40, the section being taken along a plane XZ passing through the central axis 45. This central axis extends along the thickness of the collimator 40, in the center of the latter. The collimator 40 extends between two planes P40.1 and P40.2, perpendicular to the central axis 45. These planes respectively define a first end 46 and a second end 47 of the collimator. It comprises channels 42i, 422, 423, 424, each extending between a first end 46i, 462, 463, 464 and a second end 47i, 472, 473, 474. Each first end is intended to be disposed facing an object 10 to characterize, while each second end is intended to be arranged facing a detector 20. Preferably, as shown in FIG. 1B, the collimator is arranged, facing the object 10, so that the axis center 45 of the collimator 40 coincides with the axis 12z of the incident collimated beam 12c.
    In the remainder of the text, n is a natural integer greater than or equal to 1 and less than or equal to N, N being a strictly positive integer, n denotes indifferently a channel 42n of the collimator while N denotes the number of channels of the second collimator. It is the same for the side walls 41n, defined below, or the first ends 46n or 47n, the index n relating to the channel 42n.
    Each channel 42n is delimited by at least two side walls 41n-i, 41 ", the wall 41" -i, said proximal wall, being closer to the central axis 45 than the wall 41n, said distal wall. Thus, the channels 42i, 422, 423 and 424 are respectively delimited by the side walls 410 and 41i, 41i and 412, 412 and 413/413 and 414. These side walls are made of a material sufficiently dense to significantly attenuate electromagnetic radiation in the emission energy range according to which the irradiation source 11 emits the incident radiation 12. The metallic materials are preferred, and in particular the materials whose atomic number is greater than or equal to that of the iron (26), and preferably higher or equal to that of lead (82). Lead collimators or an alloy comprising essentially Tungsten are conventionally used for this type of application. The thickness of these walls is generally less than 1 cm, or even 0.5 cm. It can vary between the proximal end and the distal end of the collimator 40. Each channel extending between the different walls is filled with a low-attenuating material, for example air.
    In the example shown, the side walls 41i, 412, 413, 414 have a substantially truncated conical shape, and extend around the central axis 45 of the collimator. The truncated-conical shape of each side wall 41 "may be defined by a vertex disposed on the central axis 45, and by an annular generatrix extending at the distal end 46" of a delimited 42n channel by said side wall, about the central axis of the collimator. Thus, in a transverse plane P4o, extending perpendicularly to the central axis 45, the cross section of each channel describes a portion of a ring whose center is located on the central axis. The term ring designates a circular or polygonal ring.
    In this example, the collimator comprises a central wall, said base wall, 41o full, whose outer radius delimits the channel 42i. This base wall extends between the central axis of the collimator and the channel closest to this central axis. This base wall is cylindrical or truncated conical. It extends around the central axis 45, so as to prevent transmission of radiation transmitted by the object in an incident direction parallel to the propagation axis 12z. According to a variant, whatever the embodiment, the collimator may comprise a hollow base wall 410. In this case, the base wall extends around the central axis 45, defining a cylinder or a cone, and defines a cavity whose central axis is the central axis 45 of the collimator. This allows a measurement, by the detector 20, of a spectrum of the radiation transmitted by the object 10 propagating along the central axis 45. When the central axis of the collimator coincides with the propagation axis 12z of the collimated beam. incident 12c, this allows a measurement, by the detector 20, of the spectrum of a radiation transmitted by the object without being deflected by the latter. This allows an estimate of the collimated radiation attenuation 12c caused by the object.
    Each side wall extends between an outer radius and / or an inner radius. These rays, at the first end 46 of the collimator, vary between a few millimeters for the wall closest to the central axis 45 to a few centimeters, for example 1 or 2 cm for the side wall furthest from the axis. central 45. At the second end 47, these external rays range from a few millimeters for the nearest wall to several centimeters, for example 6 cm for the farthest wall. The opening of a channel 42 ", that is to say the distance between the side walls delimiting it, is for example less than 1 mm at the proximal end 46n, and is between 1 mm and 1 cm. at the distal end 47n.
    Each channel 42n extends between its proximal end 46n and its distal end 47n around a median axis 44n. In FIG. 1B, the median axes 44 1, 44 2, 44 3 and 444 respectively associated with the channels 42 1, 42 2, 423 and 424 are represented. By a median axis is meant an axis extending along the center of the channel, that is, ie at equal distance from the side walls delimiting said channel. Each median axis 44n of a channel 42n is inclined relative to the central axis 45 of the collimator, thus forming an acute angle θη, said collimation angle of the channel 42 ".
    FIG. 1B also shows channels 42'i, 42'2, 42'3 and 42'4, the collimation angle of which is identical to that of channels 42i, respectively; 422, 423 and 424. Thus, in this example, several channels may have the same collimation angle.
    Each median axis 44n of a channel 42n intersects the central axis 45 of the collimator at a point Pn, called the focal point. A remarkable aspect of this collimator is that the focal points Pi, P2, P3, P4 associated with channels whose respective collimation angles θι, Θ 2, 03, 04 are different, are spaced apart from each other. In other words, and this is a significant difference from the prior art, the channels of the collimator 42n extend around median axes 44n, intersecting the central axis 45 of the collimator, so that: the median axes 44n, 44'n of two 42n channels, 42'n having the same collimation angle 0n are intersecting, and intersect at a point, said focal point Pn at the collimation angle 0n, this point being located along the axis center 45 of the collimator; the median axes 44n, 44n- of two channels 42n, 42n 'whose collimation angles (θη, θη-) are different, intersect the central axis at two different focal points Pn, Pn' located along the central axis 45 collimator.
    Each channel 42n is able to transmit a radiation 14n transmitted by the object 10 around a focal point Pn, said radiation propagating in an angular range Δθη extending around the collimation angle θη of the channel. In addition to the collimation angle θη, this angular range depends on the diameter of the channel, or its diagonal, as well as the length of the channel 42n between its first end 46n and its second end 47n. The longer this length, the more the angular range is tightened around the collimation angle θη. The smaller the opening of a channel, the narrower the angular range around the collimation angle θη. The opening of a channel designates the distance between the two proximal and distal lateral walls delimiting it.
    The fact that the focal points are spaced from each other makes it possible to simultaneously examine different parts of the object 10. Indeed, as shown in FIG. 1B, the collimator 40 is disposed between the object 10 and the detector 20, such that all or some of the focal points Pi, P2 ... P "... Pn are included in the object 10. In general, the distance between the focal point closest to the collimator and the point The focal point farthest from the collimator is between 1 and 100 cm depending on the intended applications, and preferably between 2 and 50 cm. This corresponds, in FIG. 1B, to the distance between the points Pi and P4. For applications on biological tissues, this distance is between 1 cm and 10 cm, preferably between 2 cm and 10 cm.
    FIG. 1C illustrates the definition of an angular range Δθη associated with a channel 42n. Due to its opening, this channel is capable of transmitting radiation emitted (or transmitted) by the object in an angular range Δθη bounded by a minimum collimation angle θmin and a maximum collimation angle θmax. These two limit angles are determined by representing the limits 48n, 48'n of the solid angle Ωη under which the channel 42 receives the object 10. The intersection of this solid angle Ωη with the incident beam 12c makes it possible to define an elementary volume Vn of the object seen by the channel. This elementary volume extends along a range of coordinates Δζη the central axis 45 of the collimator, called spatial extension associated with the channel 42n. For clarity, the incident beam 12c is not shown in FIG. This beam extends along a propagation axis 12z, which in this example is coaxial with the central axis 45 of the collimator 40.
    FIG. 1D shows the collimator 40, described in connection with the preceding figures, placed between an object 10 and a detector 20. The median axes 44i, 442, 444 of three channels 42ι, 422, 424, and the points respectively associated focal length Pi, P2, P4. The elementary volumes Vi, V2, V4 of the object addressed by each channel are also represented. The distribution of the focal points along the central axis 45 makes it possible to distribute the different elementary volumes examined along this axis. Thus, depending on the channel in front of which they are placed, the pixels 20, j of the detector 20 acquire a scattered radiation spectrum representative of one or other of these elementary volumes. The channels are preferably arranged so that the elementary volumes overlap as little as possible.
    The first and second ends of the collimator correspond, in this example, respectively to the planes P4o.i and P4o.2, between which the collimator 40 extends. They are distant from a height H, called collimator height, generally comprised between 5 and 100 cm, preferably between 5 and 50 cm. The higher it is, the closer the angular range Δθ "associated with each channel 42n is, which improves the angular resolution, but the collimator is more expensive, cumbersome and heavy.
    The distance di between the object 10 and the collimator 40 can be adjusted: It can be zero, the collimator being in contact with the object. It can also reach a few cm, usually being less than 10 cm II is the same for the distance d2 separating the collimator 40 from the detector 20. In general, the collimator is arranged so that several focal points, and preferably, all the focal points are included in the object 10. In this way, the detector 20 makes it possible to detect transmitted radiations 14n originating from different elementary volumes Vn of the object, each elementary volume extending around a focal point Pn.
    The detector 20 extends between two planes P20.i and P20 2, preferably perpendicular to the central axis 45 of the collimator 40. Thus, in this example, the detector extends perpendicular to the axis of propagation 12z of the beam collimated incident 12c. The thickness s of the detector 20 corresponds to the distance between the two planes P2o.i and P2o.2. It is generally between 1 and 10 mm and rises, in this example, to 5 mm.
    Each pixel 20i, j of the detector is located at a distance R, called the radial distance, from the central axis 45 of the collimator. When, as in this embodiment, the detector 20 extends perpendicular to this central axis 45, it is possible to define a group of pixels 20R comprising all the pixels 20jj equidistant from the central axis 45, and consequently from 12z axis collimated beam 12c. A pixel group 20R then corresponds to pixels 20jj whose radial distance R is identical. Due to the geometry of the collimator, each group of pixels 20r is associated with a volume element 6VR of the object, corresponding to the intersection between the solid angle δQij under which a pixel 20y of said group sees the object, with the collimated incident beam 12c. This volume element 5VR is defined as a function of a distance z between the detector and said volume element, as well as a diffusion angle θR.
    FIG. 1E represents an example of a detector, comprising parallelepipedic pixels of dimensions 2.5 mm × 2.5 mm and thicknesses ε = 5 mm, arranged according to a two-dimensional matrix of 40 pixels by 40 pixels. The central axis 45 of the collimator 40 has also been shown. The detection effective area is therefore 100 mm * 100 mm. Each pixel 20 ,,, is connected to an electronic circuit 21 allowing the collection of signals representative of the energy of a diffusion radiation transmitted by a channel 42 "located opposite said pixel. Also shown in this figure, a radial distance R of a pixel 20ij. The detector 20 may be connected to a processor 22, previously described, allowing a first processing consisting of analyzing the signals emitted by several adjacent pixels, so as to locate the point of impact of a detected radiation at a spatial resolution less than the pitch according to which are distributed these pixels. Such a treatment, known to those skilled in the art by the term sub-pixelization or over-pixelization, amounts to forming so-called virtual pixels 20 * k, i, the area of each virtual pixel being for example 1mm * 1 mm or 0.5 mm by 0.5 mm. This increases the spatial resolution of the detector 20.
    FIG. 1F represents an example of a spectrum of the radiation 12 emitted by the irradiation source 11. This spectrum represents a number of photons (on the ordinate) as a function of the energy (on the abscissa). Note the absence of significant signal below 20 keV, due to the provision of a copper attenuator screen previously mentioned. The peaks correspond to X fluorescence peaks of Tungsten. It is observed that the spectral range of this emitted radiation extends between 20 and 100 keV, which is conventional for this type of analysis.
    FIGS. 1H and 1H show a section of the collimator 40 described above, respectively according to the planes P40.i and P40.2 shown in FIG. 1D.
    The collimator 40 is in the form of an assembly of plates having openings, each plate being able to have a thickness of 1 mm. The size of each opening increases as the plate approaches the plane P40.2. Thus, the assembly of the plates forms a collimator, each channel of which is formed by the openings of the plates contiguous to one another. In each of these figures, white dotted lines, each side wall 41i, 412, 413, 414 is shown. In this configuration, each side wall describes a square generator ring about the axis 45.
    Figure 2A shows another embodiment, in which each channel 42 "of the collimator is annular. Thus, in a plane P40 extending perpendicularly to the central axis 45, each channel has a cross section describing a ring. The ring may be of polygonal or circular generatrix. Each median axis 44n of each channel 42n extends along a conical surface, extending at equal distance from the side walls 41 "-i and 41n delimiting the channel, and whose apex, included in the central axis 45, corresponds to the Pn focal point In the same way as in the previous embodiment, each channel 42n corresponds to a focal point Pn corresponding to the intersection between the central axis 44n with the central axis 45 of the collimator 40.
    FIGS. 2B and 2C show a sectional view of the collimator 40 according to the respective sectional planes P4o.i and P ^ .2, between which the collimator 40 extends. This makes it possible to observe the annular cross section of each channel.
    FIG. 2D is a perspective view of the device represented in FIG. 2A: the object 10, the collimator 40, the detector 20 and the rays 14 scattered by the object 10 are observed under the effect of the irradiation by the collimated beam 12c. Figure 2E is a sectional view of Figure 2D, the section plane passing through the central axis 45 of the collimator 40 and being parallel to this central axis. In this example, the object is composed of a fibroglandular tissue 10.1 included in a matrix 10.2 corresponding to adipose tissue. The object finally has a carcinoma 10.3 represented by a black dot
    FIG. 3 represents a characterization of a collimator similar to that represented in FIGS. 2A to 2E, comprising 10 annular channels. This collimator is made of Denal, consisting essentially of more than 90% of Tungsten, supplemented with Nickel, Iron and Cobalt. It extends between a first plane P4o.i, adjacent to the object and a second plane P4o.2, adjacent to the detector, at a height of 100 mm. The first and second planes P4o.i and P4o.2 are respectively disposed in contact with the object and the detector (di = d2 = 0). At the level of the first plane P4o.i, the median axes of the channels 42i, 422, 422, 424, 42s, 42e, 427, 42s, 42g, 4210 are respectively spaced from the central axis 45 by: 1.6 mm; 4.3 mm; 6 mm; 7.5 mm; 8.9 mm; 10.4 mm; 11.9 mm; 13.4 mm; 14.8 mm; 16.2 mm. The opening of each channel is equal to 0.5 mm. At the level of the second plane P40 2, the collimator comprises a solid central wall (or base wall), of diameter 5 mm, forming a cylinder around the central axis. It also comprises side walls 41i, 412, 413, 414, 415, 416, 417, 41s, 419, 41i0, respectively extending at a distance from the central axis 45 equal to 16.5 mm; 23 mm; 28 mm; 32 mm; 35.5 mm; 39 mm; 42 mm; 45 mm; 47.5 mm; 50 mm.
    Calculations have made it possible to determine the angular range addressed by each channel 42n. The abscissa axis represents the distance z with respect to the detector, along the Z axis, the detector being located at z = 0. The scattering angles are indicated according to the color scale presented in the margin of this figure. It is observed that apart from the channel 42i, the closest to the central axis 45 of the collimator, each channel 42 "addresses an angular range Δθ" extending about 1 ° for the channels farthest from the central axis, to a few degrees for the nearest channels. For example, the angular range associated with the channel 422 is between 6 ° and 10 °. The abscissa axis makes it possible to measure the spatial extension Δζ "addressed by each channel 42n according to the central axis 45 of the collimator, such a spatial extension having been defined in connection with FIG. The spatial extension Δζ2 corresponding to the channel 422 is represented. The channel 42i closest to the collimator has a high spatial extension because of the small angles addressed by this channel, the latter being between a few tenths of a degree and 4 degrees. .
    This figure also makes it possible to determine, for each pixel located at a radial distance R from the central axis 45, the addressed diffusion angle OR as well as the distance z, with respect to the detector, which makes it possible to define the element of volume ôVr of the object 10 seen by the pixel. The ordinate axis represents the radial distances R, the latter varying between a few mm (pixels closest to the central axis 45) and 50 mm, which corresponds to the half-width of the detector. For example, each pixel located at a radial distance R = 20 mm from the axis of the collimator 45 detects a scattering radiation transmitted by a volume element 6VR of the object 10 located along the axis of propagation 12z of the collimated beam 12c, at a range of δz distance, R = 2o between 126 mm and 130 mm from the detector, this radiation being emitted at a scattering angle OR between 8 and 9 °.
    FIG. 4 represents a similar modeling, carried out using a collimator similar to that described in the previous example, the height of which is 240 mm. The dimensions of each channel, at its proximal end 46n and its distal end 47n, are similar to those described in the previous example. This collimator extends over a height of 240 mm and is placed in contact with the object and the detector. For each channel 42n beyond the first channel 42i closest to the central axis 45 of the collimator, a reduction is observed. the angular range Δθ "as well as the spatial extension Δζ along the central axis 45 of the collimator. It is understood that such a collimator allows a finer mesh of the examined object, and a better separation of the elementary volumes Vn associated with each channel 42n. As in FIG. 3, this figure makes it possible to apprehend the angle of diffusion 0R addressed as well as the distance z, with respect to the detector, defining the volume element 6VR of the object seen by each pixel located at a distance radial R of the collimator axis 45.
    FIGS. 3 and 4 show that, according to their radial distance R with respect to the axis of the collimator 45, the different pixels of the detector make it possible to observe the object in a total depth of 30 to 40 mm, this depth being determined without taking in account the first channel 42i closest to the axis of the collimator 45, the latter addressing a greater depth due to the low collimation angle θι. This confirms the interest of such a collimator, to characterize an object at a significant depth, and without relative movement of the object and the detector.
    We will now describe a method for analyzing an object 10 using the device 1 using a collimator as previously described.
    As in FIG. 1A, the collimator 40 is arranged in such a way that its central axis 45 coincides with the axis 12z according to which the collimated incident beam 12c propagates. The detector 20 extends perpendicularly to the central axis 45. Under the effect of the Rayleigh elastic scattering, a part of the incident radiation 12c is scattered at an acute angle θ relative to the axis 12z, such that
    (1) with: d is a characteristic distance from the atomic or molecular arrangement of a material composing the object. When the analyzed material is a crystal, d corresponds to the inter-reticular distance; E denotes the energy of the scattered radiation, expressed in keV; Θ denotes the diffusion angle with respect to the trajectory of a non-diffused radiation; h and c respectively denote the Planck constant and the speed of light.
    It is common to express a quantity, called momentum transfer, and represented by the letter χ, expressed in nm'1, such that:
    (2). At each pixel 20jj, and a fortiori at each virtual pixel 20 * k, i of the detector 20 corresponds a diffusion angle Θ, corresponding to the most probable angle of a diffusion radiation 14 reaching the pixel. The advantage of over-pixelation is to lead to small pixels,
    which reduces the angular range of scattering radiation likely to reach it. Indeed, by reducing the size of the pixels, the size of each solid angle δΩΐ] under which a pixel sees the object is reduced. Sub-pixelization is interesting because it makes it possible to arrive at virtual pixels 20 * k, i of small size.
    The detector 20 extending perpendicularly to the central axis 45 of the collimator 40, the pixels 20ij or the virtual pixels 20 * k, i associated with the same scattering angle are located in an annular disposition. These pixels form a pixel group 20r, each pixel of this group addressing the same volume element 6VR of the object 10. The pixels of the same group of pixels are located at the same radial distance R of the central axis 45 collimator. The association of a pixel with a volume element designates the fact that this pixel receives a diffusion radiation essentially coming from this volume element δVr.
    The method for analyzing the material then comprises the following steps, described with reference to FIG. 5. a) irradiation of the object 10 by the irradiation source 11, preferably through the precollator 30 allowing irradiation of the material. object by a collimated incident beam 12c, propagating along a propagation axis 12z.This corresponds to step 100 of FIG. 5. b) acquisition, by each pixel 20jj of the detector, or preferably by each virtual pixel 20 * k, i, of an energy spectrum Sfj (or S ^ t) of a radiation 14 diffused by the object 10 to each pixel (or to each virtual pixel) being associated with a volume element ÔVR in the object. This corresponds to step 120 of FIG. 5. c) definition of a plurality of pixel groups 20R, each pixel group comprising pixels receiving diffusion radiation from the same volume element δVr in the object 10, said volume element being arranged along the propagation axis 12z, two different groups of pixels 20r, 20r 'receiving a scattering radiation of two elements of different volumes ôVr, ôVr' respectively located at two different distances z, z ' with respect to the detector; in this example, each pixel group corresponds to pixels located at the same radial distance R from the central axis of the collimator (45). d) combining each spectrum (Sfj or Sf £) corresponding to the pixels (20,, j, 20 * k, i) arranged in each group, so as to form an energy spectrum Sf, said combined spectrum, representative of said group, to each combined spectrum corresponding to a volume element δVR in the object. This corresponds to step 140 of FIG. 5. The combination can be a simple addition of all the spectra of the pixels of the same group. e) using the various combined spectra, determining a nature of the material constituting several volume elements (ôVr, 5Vr ') of said object. This corresponds to step 160 of FIG. 6. To each volume element 6VR may be associated a distance z with respect to the detector. Each volume element 6VR is disposed along the propagation axis 12z of the incident collimated beam 12c. Each volume element 6VR corresponds to a scattering angle θR, corresponding to the angle at which propagating scattering radiation is propagated between the volume element δVR and each pixel of the pixel group.
    The method then makes it possible to go back to the nature of the materials constituting the volume elements 6Vr, extending at different distances z with respect to the detector. Step 160 can be implemented as follows: this step assumes the establishment of a response matrix, denoted Rep, gathering the spectra obtained by each pixel, located at a radial distance R from the central axis of the collimator, when a material i is located at a distance z from the detector. Each term Rep (E, R, z, i) of this matrix represents a quantity of photons detected at energy E by a pixel located at a radial distance R from the central axis of the collimator, when a material i is located at a distance z from the detector.
    This response matrix comprises NE * NR lines and ΝΖ * Ν columns, where NE, NR, Nz and N respectively denote the number of energy channels of each spectrum, the number of radial distances R, the number of distances z and the number of materials i considered.
    The different combined spectra Sf, obtained according to NR radial distances R with respect to the central axis of the collimator, can be concatenated to constitute a vector S, called global spectrum, of dimension NE * NR. Each term S (E, R) of the vector S represents a quantity of photons detected, at the energy E, by a pixel situated at a radial distance R from the central axis of the collimator.
    The method aims to determine a proportion f (z, i) of the material i at the distance z from the detector, that is to say to determine a vector of the proportions /, of dimension (Νζ * Ν ,, 1) of which each term is a proportion f (z, t).
    Thus, S = Rep χ f, (3) where χ denotes the matrix product, each term S (E, R) of the vector S being such that:
    The matrix Rep is determined during a calibration step, carried out either with the aid of experimental measurements, the object being replaced by known standard materials; either by simulation, using computer codes simulating the transport of photons in the material; or by combining experimental measurements and simulations.
    Such a calibration step is a conventional procedure.
    The vectors S, f and the matrix Rep are explained below:
    Rep
    or Emin, Rmin, zmin, imin respectively denote the minimum indices of E, R, z and t, and Emax, Rmax, zmax, imax respectively denote the maximum indices of E, R, z and i.
    Having determined the response matrix Rep, and having obtained the global spectrum S from the measurements, an estimation / vector of the compositions f can be obtained by means of an inversion algorithm. Among the iterative inversion algorithms commonly used, it is possible to use an MLEM algorithm, which stands for Maximum Likelihood Expectation Maximization. According to such an algorithm, the value of each term of the vector fn can be obtained according to the following expression:
    the exponent n denoting the rank of each iteration.
    According to one embodiment, the method comprises a variable change step, or each spectrum Sfj is converted into a spectrum representing a distribution of momentum transfer Sfj, according to equation (2), the corresponding angle Θ at the associated angle
    at the pixel 20 ,,, (or if appropriate at the virtual pixel 20 * k, i). Such a spectrum is not an energy spectrum, but remains a spectrum representative of the energy distribution of said detected radiation. The invention may be used for providing data necessary for establishing a diagnosis. For example, it may be implemented on suspicious areas previously identified by an X-ray, X-ray, ultrasound or MRI imaging modality. This makes it possible to obtain an in-vivo characterization of tissues considered as suspect, and to avoid the use of more invasive and more traumatic techniques, such as biopsies. The fact of having a priori on the location allows to focus on suspicious areas and limit the integrated dose by the patient. Indeed, using such a priori, the device can be used so that the collimated beam axis 12z passes through the previously determined suspect zone. The invention can also be implemented in other non-destructive materials control applications: baggage control, detection of illegal materials, control of the integrity of structures ...
    权利要求:
    Claims (19)
    [1" id="c-fr-0001]
    A collimator (40), intended to be interposed between an object (10) and an ionizing electromagnetic radiation detector (20), the collimator extending between a first end (46) and a second end (47), around a central axis (45), the collimator comprising a plurality of channels (42 "), each channel being delimited by side walls (41" -i, 41n), the collimator being such that: each channel (42n) comprises a median axis (44n), said median axis extending, in the center of the channel, between said lateral walls delimiting said channel; the median axis of each channel (42n) forms an acute angle (θ "), said collimation angle of the channel, with the central axis (45) of the collimator; each channel (42n) is associated with a focal point (Pn) formed by an intersection between the median axis (44 ") of said channel and said central axis (45) of the collimator; the collimator being characterized in that it comprises at least two channels (42n, 42n) whose collimation angles (θη, θη) are different, the focal points (P ", P") respectively associated with these channels being different and spaced from each other along said central axis (45) of the collimator (40).
    [2" id="c-fr-0002]
    2. Collimator according to claim 1, comprising a plurality of channels of the same collimation angle (θη), said channels extending around the central axis (45) of the collimator, the focal points (Pn) of said channels being merged.
    [3" id="c-fr-0003]
    A collimator according to claim 1 or claim 2, wherein at least one channel has a cross section in a plane (P40) perpendicular to said central axis (45), said cross section forming all or part of a ring around the central axis (45).
    [4" id="c-fr-0004]
    The collimator of claim 3, wherein in said cross section forms a ring about the central axis (45).
    [5" id="c-fr-0005]
    5. A collimator according to any one of claims 3 or 4, wherein each ring is circular or polygonal.
    [6" id="c-fr-0006]
    6. A collimator according to any one of the preceding claims, wherein at least two focal points are spaced, along said central axis (45) of the collimator, a distance greater than 2 cm.
    [7" id="c-fr-0007]
    7. Collimator according to any one of the preceding claims, wherein each side wall (41n_i, 41n) delimiting a channel (42n) is made of a material whose atomic number is greater than 26.
    [8" id="c-fr-0008]
    8. Collimator according to any one of the preceding claims, each channel (42 ") being delimited by a so-called proximal side wall (41n-i) and a so-called distal side wall (41n), the proximal wall (41n-i) being closer to the central axis (45) than the distal wall (41n), each of these walls extends between the first end of the channel (46n) and the second end of the channel (47n), forming a frustoconical surface defined: by a vertex, located on the central axis (45); and, at said second end (47n), by a generator describing an entire or part of a ring.
    [9" id="c-fr-0009]
    9. A collimator according to any one of the preceding claims, comprising a so-called base wall (41o), extending around the central axis (45) by describing a cylinder or a truncated cone, greater than 5 mm.
    [10" id="c-fr-0010]
    10. Apparatus for analyzing (1) an object (10), comprising: an irradiation source (11), capable of producing an ionizing electromagnetic radiation (12) propagating to a support (10s) suitable for receiving said object (10); a first collimator (30) disposed between the irradiation source and the support (10s), the first collimator having an opening (32) capable of forming a collimated beam (12c) propagating along a propagation axis (12z), to the support (10s); a detector (20), comprising pixels (20jj, 20 * ki), each pixel being able to detect ionizing electromagnetic radiation, and forming an energy spectrum (Sf7, Sjy); a second collimator (40) disposed between the support (10s) and the detector (20), the second collimator being capable of selectively directing radiation emitted (14 ") by said object, held by the support (10s), towards said detector, as a function of a diffusion angle (θ ") of said radiation (14n) emitted by the object; characterized in that said second collimator is a collimator according to any one of claims 1 to 9; in such a way that each channel (42n) transmits to the detector a radiation (14n) emitted by an elementary volume (Vn) of the object, disposed on the support, extending around a focal point (Pi ... Pn) defined by the second collimator, according to a predetermined angular range (Δθη).
    [11" id="c-fr-0011]
    11. Apparatus (1) for analyzing an object according to claim 10, wherein the second collimator (40) is arranged so that its central axis (45) is coaxial with the axis of propagation (12z) of the incident collimated beam (12c).
    [12" id="c-fr-0012]
    12. Apparatus (1) for analyzing an object according to claim 10 or claim 11, wherein the detector (20) extends in a plane (P20) perpendicular to said central axis (45) of the second collimator.
    [13" id="c-fr-0013]
    13. Device (1) for analyzing an object according to any one of claims 10 to 12, wherein the detector (20) is connected to a microprocessor (22) capable of subdividing each pixel (20jj) of the detector into virtual pixels (20 , i).
    [14" id="c-fr-0014]
    14. Device (1) for analyzing an object according to claim 13, wherein a plurality of pixels or virtual pixels are arranged in the extension of the same channel (42 ").
    [15" id="c-fr-0015]
    15. A method of characterizing an object (10) using a device according to any one of claims 10 to 14, comprising the following steps: a) placing the object (10) on the support ( 10s) of the device and irradiation of the object with the aid of the irradiation source (11), so as to form a collimated incident beam (12c) propagating towards the object (10) along an axis of propagation ( 12z), the object being arranged in such a way that several focal points (Pi ... Pn), defined by the second collimator (40), are placed in said object; b) with the aid of each pixel (20,, j, 20 * k, i) of the detector 20, detection of radiation scattered by the object (10) following its irradiation by said collimated incident beam (12c) and forming a spectrum representative of the energy distribution of said detected radiation (S5, S £;); c) defining a plurality of groups of pixels (20R), each pixel group receiving diffusion radiation from the same volume element (6VR) of said object (10), said volume element being disposed along said axis of propagation (12z), two groups of different pixels (20R, 20R ') receiving diffusion radiation of two elements of different volumes (δVR, δVR'); d) for each pixel group defined in the previous step, combining the spectrum acquired by each pixel, so as to establish a spectrum, said combined spectrum (Sf) associated with said pixel group; e) using the combined spectra (Sf) respectively associated with different groups of pixels (20r), determining a nature of the material constituting several volume elements (ôVr, ôVr ') of said object (10).
    [16" id="c-fr-0016]
    16. The method of claim 15, wherein the central axis of the second collimator (45) coincides with the propagation axis (12z) of the collimated beam (12c); the detector (20) extends perpendicularly to the axis of the collimator (45), each pixel group comprising pixels located at the same distance, said radial distance (R) from said central axis of the collimator (45).
    [17" id="c-fr-0017]
    The method of any of claims 15 or 16, wherein the object is a biological tissue.
    [18" id="c-fr-0018]
    18. A method according to any one of claims 15 to 17, wherein the direction of the collimated incident beam (12z) is defined from a priori resulting from a prior inspection of the object.
    [19" id="c-fr-0019]
    The method of claim 18, wherein said pre-inspection is performed by X-ray or X-ray tomography or ultrasound or Magnetic Resonance Imaging.
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    优先权:
    申请号 | 申请日 | 专利标题
    FR1560443A|FR3043247B1|2015-10-30|2015-10-30|COLLIMATOR FOR X-DIFFRACTION SPECTROMETRY, ASSOCIATED DEVICE AND ITS USE|
    FR1560443|2015-10-30|FR1560443A| FR3043247B1|2015-10-30|2015-10-30|COLLIMATOR FOR X-DIFFRACTION SPECTROMETRY, ASSOCIATED DEVICE AND ITS USE|
    EP16196005.9A| EP3163582B1|2015-10-30|2016-10-27|Device comprising a collimator for x-ray diffraction spectrometry and its use|
    JP2016211403A| JP6915980B2|2015-10-30|2016-10-28|Collimator for X-ray diffraction spectroscopy, related equipment and its use|
    US15/337,654| US10121561B2|2015-10-30|2016-10-28|Collimator for X-ray diffraction spectroscopy, associated device and its use|
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