Rotating Collimators for X-ray Inspection Systems

Abstract

A collimation device (1) for an X-ray detection system, the collimation device (1) comprising: a collimator, the collimator comprising a substantially planar support (20), the support being made of a material having partial or zero radiotransparency, the support (20) being rotatably movable around a rotation axis (Δ), the rotation axis passing through the support and being perpendicular to a first surface of the support (20), the first surface of the support being a plane of incidence of X-rays, referred to as a principal plane (P) of the support, the support (D) being provided with a slit (30) on the first surface, the slit being completely transparent to X-rays, and being configured to generate an X-ray stream when the collimator is exposed to an X-ray source (10), the slit (30) extending longitudinally in the principal plane of the support along an axis at a non-zero distance (d) from the rotation axis (Δ), the slit (30) extending through the entire thickness of the support (20).

Description

Technical Field

[0001] The present application relates to the field of X-ray detection systems and more particularly to the field of spatially localized elements in X-ray detection systems.

[0002] The present application is also applicable to X-ray imaging, and in particular to "interventional" imaging, wherein it is sought to accurately determine the position of a tool while acquiring an image, for example during a surgical intervention or during an operation using the tool. Background Art

[0003] Document FR 2 841 118 proposes an X-ray imaging system comprising means for determining the position of a radiographic unit using a test pattern fixed to an object whose image is acquired.

[0004] In such systems, the image of the test pattern interferes with the image of the object that one wishes to investigate.

[0005] Document US Pat. No. 6,490,475 proposes a fluoroscopic system in which markers are used to determine the position of elements of the system. Digital processing is then performed to remove traces of these markers from the final image.

[0006] Document US Pat. No. 7,065,393 relates to a method for calibrating an X-ray imaging system using inertial sensors arranged on different elements of the system.

[0007] This type of sensor often suffers from a large error accumulation and low precision, so there are problems with reliably determining the position of the element equipped with the sensor in an X-ray imaging system.

[0008] Patent application FR3042881 proposes a device for X-ray imaging comprising a rotating collimator comprising two slits. This device makes it possible to reliably determine the position in a given reference system of an element provided with an X-ray sensor for receiving an X-ray beam from the slits in the collimator.

[0009] This application is particularly intended to simplify the device of patent application FR3042881. Summary of the invention

[0010] To this end, according to a first aspect, the present application relates to a collimation device for an X-ray detection system, the collimation device comprising:

[0011] - a collimator comprising a substantially planar support made of a material with partial or zero radiotransparency, the support being rotatably movable about an axis of rotation passing through the support and being perpendicular to a first face of the support, the first face of the support being a plane of incidence for the X-rays, referred to as a principal plane of the support,

[0012] The support is provided with a single slit on a first face, the slit being completely transparent to X-rays and being configured to generate an X-ray flux when the collimator is exposed to an X-ray source, the slit extending longitudinally in a main plane of the support along an axis at a non-zero distance from the rotation axis, and the slit extending through the entire thickness of the support.

[0013] Such a single-slit collimator enables a simplified implementation of the collimation device.

[0014] In one or more embodiments, the slit has a projection in the main plane of the support having a rectangular or trapezoidal shape.

[0015] According to a second aspect, another subject matter of the present application relates to an X-ray detection system, the detection system comprising:

[0016] - an X-ray source configured to emit an X-ray beam;

[0017] - a collimator according to the first aspect, the collimator being placed to receive the X-ray beam in a plane of incidence of a support of the collimator;

[0018] - a drive device configured to rotate the support of the collimation device around an axis of the support at a fixed rotational angular velocity;

[0019] - at least one X-ray detection element, at least one X-ray detection element is placed in the collection field opposite to the support with respect to the X-ray source, so as to collect X-rays when a part of the X-ray beam, which passes from a first face of the support through a slit in the support to the opposite face, reaches the detection element in question during a rotation of the support.

[0020] In one or more embodiments, a detection element from the at least one X-ray detection element is configured to detect X-rays passing through the slit at two consecutive times when the support rotates, the first time corresponding to a first angular position of the slit, and the second time corresponding to a second angular position of the slit, the first angular position and the second angular position defining an intersection in a main plane of the support, the intersection corresponding to a projected position of the detection element in the main plane of the support;

[0021] The detection system comprises a processing unit configured to determine the projection position of the detection element in the main plane of the support according to the first angular position and the second angular position. Thus, for each rotation (complete rotation), two consecutive times and thus two angular positions are obtained. For example, the first angular position and the second angular position are determined by the two consecutive times and the angular speed of rotation of the support.

[0022] In another embodiment, the determination of the first angular position and the second angular position involves an optical fork, and the X-ray detection system further includes a second support, which is fixed to the support or forms an integral part of the support, and the second support includes a series of N windows, which are angularly uniformly distributed around a circular periphery centered on the rotation axis of the support, and the series of N windows includes a reference window having a size different from the other windows, and the other windows are indexed relative to the reference window.

[0023] In this case, one detection element from the at least one X-ray detection element is configured to detect X-rays passing through the slit for a first angular position and a second angular position of the second support, the first angular position and the second angular position of the second support defining an intersection in the main plane of the support, the intersection corresponding to the projection position of the detection element in the main plane of the support. In this embodiment, the X-ray detection system comprises an optical fork, the optical fork being provided with an emitter and a detector, the emitter being configured to emit a light wave, the detector being configured to detect the light wave, the fork being configured to generate an electrical pulse when the receiver receives the light wave at any of the windows passing between the emitter and the receiver, the first angular position and the second angular position each corresponding to the passed window. Then, the processing unit is configured to determine the first angular position and the second angular position based on the index of the two windows generating the electrical pulse, the electrical pulse being closest in time to the two consecutive times for which the detection element performs detection.

[0024] In one or more embodiments, the processing unit is configured to determine the distance between a plane containing the detection element and parallel to the main plane of the support and the X-ray source based on the radiation duration of the detection element, based on the rotation angular velocity of the support, based on the distance between the X-ray source and the support, based on the width of the slit, and based on the distance between the projection position in the main plane of the support and the intersection of the rotation axis of the support.

[0025] In one or more embodiments, the X-ray source is a pulse source, which is configured to emit X-rays in an emission cycle consisting of two modes used alternately, one mode is an X-ray emission mode, and the other mode is an X-ray non-emission mode. Then, one of the X-ray detection elements is configured to detect the X-rays passing through the slit in a manner synchronized with the X-ray emission cycle.

[0026] In one or more embodiments, when the X-ray source is a pulse source, the support of the collimation device according to the first aspect of the present application is made of an X-ray scintillator material. Then, when the support is exposed to the X-ray source, the support is capable of emitting scintillation photons. The detection system according to the second aspect of the present application further includes a photodiode, which is configured to detect scintillation photons and emit a photocurrent generated by the detected scintillation photons to trigger the detection element to detect and collect X-rays passing through the slit in the support.

[0027] In this case, the processing unit may be configured to use the photocurrent emitted by the photodiode to automatically feedback control the rotational angular velocity of the support relative to the duration of the pulse from the pulse source. The rotational velocity is such that the collimator rotates at least one revolution within the duration of the pulse.

[0028] According to a third aspect, the present application relates to an X-ray imaging system, the X-ray imaging system comprising: an X-ray detection system according to the second aspect; a plurality of acquisition elements, the plurality of acquisition elements forming an acquisition matrix placed in an acquisition field of the imaging system, each acquisition element in the acquisition matrix being configured to acquire X-ray flow accumulation when a support of a collimator of the detection system rotates around an axis of the support, the acquisition matrix being configured to acquire radiographic images based on acquisitions respectively performed by the acquisition elements constituting the matrix during a given time period.

[0029] In one or more embodiments, the X-ray imaging system further includes a plane aperture, which is placed between the X-ray source and the single-slit rotating support and defines a field of view, the projection of which on the acquisition matrix does not exceed the size of the acquisition matrix. The plane aperture makes it possible to avoid irradiating an area other than an area including a plurality of acquisition elements forming the acquisition matrix, and spatially limit radiation from the X-ray source, thereby, for example, avoiding irradiating a doctor or operator using the X-ray imaging system.

[0030] In one or more embodiments, the X-ray source is a pulse source, and the pulse source is configured to emit X-rays in an emission cycle consisting of two modes used alternately, one mode is an X-ray emission mode, and the other mode is an X-ray non-emission mode. In this case, the acquisition matrix is ​​configured to acquire radiographic images in a manner synchronized with the X-ray emission cycle.

[0031] When the X-ray source is a pulse source, the support is made of an X-ray scintillator material, and when the support is exposed to the X-ray source, the support is capable of emitting scintillation photons. Then, the imaging system further includes a photodiode, which is configured to detect the scintillation photons and emit a photocurrent generated by the detected scintillation photons to trigger the acquisition matrix to acquire at least one radiographic image.

[0032] In this case, the processing unit may be configured to use the photocurrent emitted by the photodiode to automatically feedback-control the rotational angular velocity of the support relative to the duration of the pulse from the pulse source.

[0033] According to a fourth aspect, another subject matter of the present application relates to a method for positioning a detection element of an X-ray detection system, the X-ray detection system being the X-ray detection system according to the second aspect, the method comprising the following steps:

[0034] - rotating the support of the collimation device around the rotation axis of the support at a fixed rotational angular velocity;

[0035] - during the rotation of the support, exposing the support to an X-ray beam from an X-ray source;

[0036] - the detection element detects X-rays passing through the slit in the support at two consecutive times, a first time corresponding to a first angular position of the slit and a second time corresponding to a second angular position of the slit,

[0037] - the processing unit determines a projected position of the detection element in a main plane of the support based on the first angular position and the second angular position.

[0038] The first angular position and the second angular position may be determined as a function of two consecutive times and additionally as a function of the rotational angular velocity of the support.

[0039] In one or more configurations, where the X-ray detection system according to the second aspect comprises a second support and an optical fork, the method comprises the following steps:

[0040] - rotating the support of the collimation device around the rotation axis of the support at a fixed rotational angular velocity;

[0041] - during the rotation of the support, exposing the assembly formed by the support and the second support to an X-ray beam from an X-ray source;

[0042] - detecting electrical pulses generated when a receiver receives a light wave at any of the windows passing between the transmitter and the receiver of the optical fork;

[0043] - a detection element detects X-rays passing through the slit in the support for a first angular position of the second support and a second angular position of the second support;

[0044] - The processing unit determines the projection position in the main plane of the support based on the first angular position and the second angular position, the first angular position and the second angular position being obtained based on the index of two windows generating electric pulses which are temporally closest to two consecutive times for which the detection element performs detection.

[0045] In one or more embodiments, the positioning method according to the fourth aspect further includes the following steps: the processing unit determines the distance between the plane passing through the detection element and parallel to the collimator and the X-ray source based on the radiation duration of the detection element, the rotation angular velocity of the support, the distance between the X-ray source and the support, and the width of the slit.

[0046] In the case where the X-ray source is a pulsed source, and in the case where the detection system comprises a photodiode, the processing unit uses the photocurrent emitted by the photodiode to automatically feedback-control the rotational angular velocity (V) of the support relative to the duration of the pulse from the pulse source. This makes it possible to ensure a rotational velocity of at least 360° within the duration of the pulse.

[0047] Another subject matter of the present application relates to an X-ray imaging method for implementing an X-ray imaging system, the X-ray imaging system being the X-ray imaging system according to the second aspect, the imaging method comprising the following steps:

[0048] - rotating a support of a collimator of the imaging system at a fixed rotational angular velocity about an axis of rotation of the support;

[0049] - during the rotation of the support, exposing the support to an X-ray beam from an X-ray source;

[0050] - the acquisition elements of the acquisition matrix detect X-rays during the rotation of the support;

[0051] - Acquisition of radiographic images based on the detections respectively performed by acquisition elements of the acquisition matrix during a given period of time.

[0052] In the case where the X-ray imaging method is implemented by an X-ray imaging system including a pulse source, and wherein a support of the collimator is made of an X-ray scintillator material, the support being capable of emitting scintillation photons when the support is exposed to the X-ray source, the X-ray imaging system further comprising a photodiode configured to detect the scintillation photons and emit a photocurrent generated by the detected scintillation photons to trigger the acquisition of at least one radiographic image by an acquisition matrix, the method comprising the following steps:

[0053] - rotating a support of a collimator of the imaging system at a fixed rotational angular velocity about an axis of rotation of the support;

[0054] - during the rotation of the support, exposing the support to an X-ray beam from an X-ray source;

[0055] - the acquisition elements of the acquisition matrix detect X-rays during the rotation of the support;

[0056] - the support emits scintillation photons;

[0057] - Photodiode detects scintillation photons,

[0058] - a photodiode emits a photocurrent generated by the detected scintillation photons to trigger the acquisition of at least one radiographic image by the acquisition matrix,

[0059] - Acquisition of radiographic images based on the detections respectively performed by acquisition elements of the acquisition matrix during a given period of time.

[0060] In this case, the processing unit can use the photocurrent emitted by the photodiode to automatically feedback control the rotational angular velocity of the support relative to the duration of the pulse of the pulse source, so that the acquisition of the radiographic image based on the detection performed by the acquisition elements of the acquisition matrix respectively is temporally windowed in the X-ray emission mode of the emission period of the pulse source. An image can be constructed by accumulating the signals detected over one or more time windows. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Other advantages and features of the present application will become apparent from the following description given by way of non-limiting example and with reference to the accompanying drawings:

[0062] [ Figure 1 ] shows a collimation device according to one embodiment.

[0063] [ Figure 2 ]The concept of partial radiotransparency is illustrated using quantitative data associated with different materials.

[0064] [ Figure 3 ] is a simplified representation of an X-ray inspection system.

[0065] [ Figure 4 ] shows aspects of calculating the position of the projection in the plane of the support of the collimation device.

[0066] [ Figure 5 ] schematically illustrates an X-ray detection system according to an exemplary embodiment.

[0067] [ Fig. 6A ] is a diagram showing the principle of an optical fork.

[0068] [ Figure 6B ] schematically shows the working principle of the phase-locked loop.

[0069] [ Figure 7 ] shows the measurement results at times t_α and t_β for three different positions of the X-ray detection element placed in the model body.

[0070] [ Figure 8 ] shows different results for positioning the detection element obtained by an embodiment of the positioning method.

[0071] [ Fig. 9 ] shows the radiation of a flow from a slit in a collimation device to a detection element according to an exemplary embodiment.

[0072] [ Fig.10 ] schematically illustrates an X-ray imaging system according to an exemplary embodiment.

[0073] [ Fig.11 ] shows a scanning of a field of view by a series of X-ray streams generated by rotating a collimation device according to an exemplary embodiment.

[0074] [ Fig.12 ] shows three radiographic images obtained by an embodiment of an X-ray imaging method.

[0075] [ Fig.13 ] shows an embodiment of a slit in a collimation device according to an exemplary embodiment.

[0076] [ Fig.14A ]and[ Fig. 14B ] respectively show an embodiment of a collimation device capable of calibration according to an exemplary embodiment. DETAILED DESCRIPTION

[0077] Figure 1 A collimation device 1 for an X-ray detection system 2 is shown. The collimation device 1 comprises a collimator comprising a substantially planar support 20 made of a material having partial or zero radio-transparency. Figure 1 In the figure, the support 20 is shown in the form of a disk, but the support may take any other two-dimensional form. The support 20 is rotatably movable around a rotation axis Δ15, which passes through the support 20 and is perpendicular to a first face of the support 20, the first face of the support 20 serving as an incident plane for the X-rays and referred to as a principal plane P of the support. The support 20 is provided with a slit 30, which extends longitudinally in the principal plane P of the support and passes through the entire thickness e of the support 20. The slit 30 is completely transparent to the X-rays and is located at a non-zero distance d from the rotation axis Δ15. The slit may be rectangular in shape, such as Figure 1 In this case, the slit has a width l. The slit can also be trapezoidal in the main plane of the support.

[0078] A collimating device (or collimator) makes it possible to limit the incident light beam in space. In the context of the present application described herein, the light beam upstream of the collimating device is, for example, of the "cone beam" type, while the light beam downstream of the collimating device is of the "fan beam" type. The collimated light beam at the output of the collimating device scans space and in particular makes it possible to determine the position of a detection element in space (for example the position of a sensor attached to a tool to be positioned).

[0079] In practice, the slit has a certain thickness (corresponding to the thickness of the support) and may have a 3D shape corresponding to a cuboid or a non-rectangular cross section (in a plane perpendicular to the support). Figure 2 A and Figure 2 As explained in B, the tilt can be provided based on the divergence of the X-ray beam emitted from the X-ray source.

[0080] The term “partial radiotransparency” is understood to mean a non-zero percentage attenuation of the monoenergetic photon flux. This percentage depends on the material used for the support 20 and on the thickness of the support 20. Figure 2 Different values ​​of material thickness (in millimeters) are shown for which, for a given photon energy (in keV), a 95% attenuation of the incident monoenergetic photon flux is obtained. 4 The support member 20 manufactured with a thickness of 0.9 mm enables a monoenergetic photon beam with an energy of 100 keV to be attenuated by 95%.

[0081] The expression "completely radio-transparent" means that the slit 30 exhibits no absorption of the X-ray beam or no significant absorption of the X-ray beam. For example, the thickness or the material of the slit defined in the support or a combination of these two parameters may be selected to obtain a slit 30 with complete radio-transparency. This would occur, for example, if the slit corresponds to an opening in the support (i.e., the slit is filled with air).

[0082] By "zero radiotransparency" is meant a complete opacity to X-rays. More precisely, by "zero radiotransparency" is meant an attenuation percentage of the monoenergetic photon flux of more than 99%. By "partial radiotransparency" is meant an attenuation percentage of the monoenergetic photon flux of between 1% and 99%, for example, higher than 10% or higher than 50%. An attenuation percentage higher than 80% allows a good compromise to be obtained between the radiation level and the quality of the image that can be acquired. In this case, the collimator strongly absorbs the X-ray beam.

[0083] Figure 3 is a representation of an X-ray detection system 2. The X-ray detection system 2 comprises:

[0084] - an X-ray source 10, which generates an X-ray beam,

[0085] - a collimation device 1 according to any of the embodiments described in this application,

[0086] a drive device configured to rotate the support 20 of the collimation device 1 at a fixed angular velocity V about an axis of rotation Δ of the support 20 ,

[0087] At least one X-ray detection element, placed in the acquisition field opposite the support 20 with respect to the X-ray source 10 .

[0088] The detection element is placed to collect X-rays when the X-ray flow (corresponding to a portion of the beam generated by the X-ray source 10) passes from the plane of incidence through the slit 30 to the opposite face of the support of the collimator and to the detection element under consideration. The geometry of this X-ray flow depends on the shape of the slit 30. For example, the geometry of the X-ray flow can be a fan-shaped geometry. For example, the X-ray flow can be a planar flow.

[0089] For example, the X-ray source 10 is an X-ray tube operated at an inter-electrode voltage between 40 kV and 125 kV.

[0090] In the first embodiment, when the support 20 is rotated by the driving device, and the collimation device 1 is exposed to X-rays from the X-ray source 10 while the support 20 is rotating, the detection element DT intercepts the high-intensity X-ray flow generated by the slit 30 at two times, namely, the first time t_α and the second time t_β. The first time t_α corresponds to the first angular position α, and the second time t_β corresponds to the second angular position β. The first angular position α and the second angular position β of the slit 30 define an intersection C in the main plane P of the support, and the intersection C corresponds to the projection position PT of the detection element DT in the main plane of the support 20. The intersection C also corresponds to the intersection of the plane defined by the two X-ray flows intercepted by the detection element DT and the intersection line of the main plane P of the support.

[0091] Therefore, by using a rotating support with only one slit that is eccentric with respect to the rotation axis of the collimator, the position of the intersection point C can be determined. During the rotation of the support, the detection element DT is irradiated twice in two different radiation planes by the X-ray beam that passes through the slit. The intersection of these two planes is the straight line connecting the X-ray source and the detection element DT. Therefore, the intersection point can be located. Here, the following assumption is made: the detection element DT does not move during the rotation of the support, because the rotation speed of the rotating collimator is high enough (for example, one rotation every 25 milliseconds), and the movement speed of the detection element DT is low enough that the displacement of the detection element DT during one rotation of the collimator is negligible.

[0092] Figure 4 The schematic diagram shows the first angular position α and the second angular position β at which the detection element DT intercepts the X-ray stream generated by the slit F at the first time t_α and the second time t_β, respectively. The position α corresponds to Figure 4 The upper left corner of the figure, and the position β corresponds to Figure 4 The intersection point C corresponding to the projection position PT of the detection element DT in the main plane of the support 20 is also Figure 4 shown in the bottom figure.

[0093] The X-ray detection system 2 may further comprise a processing unit 50 configured to determine the projection position PT or C of the detection element (DT) in the main plane of the support (P) based on two consecutive times (t_α) and (t_β) determined for the detection element (DT) and the rotational angular velocity V of the support. Specifically, by considering a reference system located in a space defined by a plane (xOy), where O is the intersection of the rotation axis Δ with the main plane P of the support, and the axis Oz is equal to the rotation axis Δ, the coordinates xc and yc of the projection position of the detection element DT in the main plane P of the support are the solutions of the system of equations:

[0094] [Formula 1]

[0095] x C cosα+y C sinα=d

[0096] [Formula 2]

[0097] x C cosβ+y C sinβ=d

[0098] Wherein, d is the distance between the slit 30 and the rotation axis Δ, sin represents the trigonometric sine function, and cos represents the trigonometric cosine function.

[0099] These two equations form a linear system with a single solution. Specifically, the determinant of this linear system is equal to sin(β-α) and is strictly positive, because the angles α and β are always different, because the slit does not pass through the intersection O between the support 20 and the axis of rotation Δ, and because the difference (diff=β-α) is always strictly less than or equal to π.

[0100] The angles α and β can be calculated from the measured values ​​of the first time t_α and the second time t_β, and from the known rotational angular velocity V of the support 20 .

[0101] Therefore, the coordinates xc and yc, in other words, the position of the projection position C of the detection element DT in the main plane P of the support, can be determined based on the angles α and β based on equations 1 and 2. Knowing the coordinates xc and yc makes it possible to determine that the detection element DT is located on a straight line passing through the X-ray source 10 and that the point C with coordinates xc and yc is located in the main plane P of the support. Therefore, only by measuring the first time t_α and the second time t_β, the detection element DT is located two-dimensionally in the main plane P of the support. This can then be projected by using the projection matrix of the assembly formed by the X-ray source 10 and the collimation device, in the radiological image formation plane, which is located downstream of the detection element DT. The mathematical form for projecting the element in such an image formation plane can be found in patent application WO2017072125 (A1). This projection position can be used for a previously acquired radiological image, or in real time in the case of a radiological image acquired simultaneously with the detection of the element DT and the calculation of this projection position.

[0102] Figure 5 A detection system 2 according to a second aspect of the present application is schematically shown, depicting an X-ray source 10 in the form of an X-ray tube, a CdWO 4 The collimator composed of the support member, the detection element DT based on gallium nitride (GaN) and the processing unit 50, the collimator is fixed to a motor, the motor can rotate the support member 20 around the rotation axis, Figure 5 In the case where the rotation axis is horizontal, the detection element DT is placed in a cylindrical mold body made of poly(methyl methacrylate) (PMMA), and the processing unit 50 includes a field programmable gate array (FPGA).

[0103] Fig. 6A The operating principle of an optical fork for measuring angles is schematically shown.

[0104] In one embodiment, angles α and β can be measured using an optical fork. The second support 20b can be positioned parallel to the main plane P of the support. The second support 20b is fixed to the support 20 or forms an integral part of the support 20. The second support 20b may include a series of N openings (hereinafter referred to as windows), which are transparent in the visible light or near-infrared range and are angularly uniformly distributed around a circular periphery centered on a point corresponding to the intersection between the second support 20b and the rotation axis Δ15. The N windows are indexed relative to a reference window, which may correspond to a window that is wider (or relatively narrower) than the other windows.

[0105] The optical fork is provided with a transmitter 21 and a receiver 22 facing each other. The transmitter 21 emits a light wave, which is picked up by the receiver when it passes through one of the windows. Therefore, when the window enables the signal to pass from the transmitter to the detector, an electrical pulse is generated. If the reference window is wider (or relatively narrower), the electrical pulse obtained for the reference window will be wider (or relatively narrower) than the electrical pulse received for the other windows.

[0106] When the collimation device 1 is exposed to X-rays from the X-ray source 10 while the support 20 is rotating, the detection element DT is exposed to the X-rays passing through the slit 30 at a first angular position α and a second angular position β. The electrical pulses transmitted by the optical fork are temporally closest to the two detection times of DT, so that the angles α and β of the support 20b can be directly determined by determining the index of the two corresponding windows, thereby determining the angles α and β of the support 20. The index of the window is determined by counting the number of pulses detected after the reference pulse generated in the reference window. In a configuration mode with N windows, the accuracy of the known angles α and β can be 360 / N°. Therefore, the coordinates xC and yC of the position of the projection position C of the detection element DT in the main plane P of the support can be determined based on the values ​​of the measured angular positions α and β. This configuration makes the determination of the angles α and β more robust because the measurement system is independent of possible changes in the rotation speed of the support 20.

[0107] In a variant of this embodiment with an optical fork, the second support 20b may include a series of a limited number of index windows, for example, 360 fully indexed windows. In this variant, the processing unit (50) includes a system implementing a phase-locked loop (PLL) that makes it possible to obtain an angular resolution greater than the angular resolution in the case of separating two consecutive detection windows. In particular, the phase-locked system transmits an electrical signal at a frequency that is a multiple of the frequency of the electrical signal transmitted by the optical fork and is in phase with the electrical signal transmitted by the optical fork. Thus, between two consecutive windows separated by an angle of 1°, the processing unit 50 can generate a signal that is ten times faster than the frequency of the electrical pulses at the output of the optical fork. This configuration makes the system for measuring angles α and β more precise by providing an enhanced angular resolution.

[0108] Figure 6B The working principle of the phase-locked loop is schematically shown. Signal 61 is the signal transmitted by the optical fork (N=13). Signal 62 is the signal transmitted by the phase-locked system (the signal is in phase and the frequency is three times the frequency of the signal transmitted by the optical fork, i.e. 39 pulses). Signal 63 is the signal transmitted by the detection element DT, which includes pulses at times t_α and t_β. Then, as Figure 6BAs shown in the last row at the bottom, the angles α and β of the support member 20 are determined as follows: α is approximately equal to (11 / 39)*360°, and β is approximately equal to (27 / 39)*360°.

[0109] Figure 7 The measurement results at time t_α and t_β at three different positions of the X-ray detection element DT placed in the model body made of PMMA at distances of 4 mm, 7 mm and 12 mm respectively from the rotation axis Δ are shown. The difference between time t_α and t_β at a distance of 4 mm is greater than the difference between time t_α and t_β at a distance of 12 mm. Specifically, the closer the detection element DT is to the rotation axis Δ, the closer the projection position of the detection element DT on the main plane P of the support is to the rotation axis Δ, and the speed of irradiating the slit portion of the projection position is slower.

[0110] Figure 8 The different results of positioning the previous detection element DT obtained by implementing the above detection system by an embodiment of the positioning method according to the invention are summarized. Figure 8 In the top table, the support rotates 1000 times per minute. Figure 8 In the table at the bottom, the support rotates 1500 times per minute). The number of fluoroscopic pulses per second is 60 and 38 respectively. The projection positions P1, P2, P3 are the positions determined for the three detection elements. The measurement result of the radial distance r from the detection element DT to the rotation axis Δ is consistent with the actual distance. Millimeter-level accuracy is obtained.

[0111] In another aspect of the present application, the processing unit 50 of the above-mentioned X-ray detection system 2 can also be configured to measure the radiation duration value t of the detection element DT according to the radiation duration measurement value t irr , according to the rotational angular velocity V of the support, according to the distance d between the X-ray source 10 and the support 20 SS And the distance L between the plane passing through the detection element DT and parallel to the collimator and the X-ray source 10 is determined according to the width l of the slit 30. Determining the distance L makes it possible to spatially position the detection element DT in three dimensions.

[0112] By assuming that the X-ray source 10 is divergent, it can be shown that:

[0113] [Formula 5]

[0114] L=t irr rV SS / l

[0115] where t irr represents the radiation duration of the detection element DT,

[0116] According to the design, dSS is the distance between the X-ray source 10 and the support 20, and r is the distance between the projection position C in the main plane P of the support and the intersection of the axis Δ with the support 20. This formula assumes the use of a divergent X-ray source 10, so that it can be stated that the farther the detection element DT is from the X-ray source 10, the longer the radiation duration of the detection element DT.

[0117] Fig. 9 It shows the propagation of a plane X-ray stream from a slit 30 of a support 20 irradiated by an X-ray source 10 which exhibits divergence to the detection element DT. The further the detection element DT is from the X-ray source 10, the broader the signal received by the detection element DT becomes in time.

[0118] In particular, it is conceivable that the detection element DT is a miniaturized X-ray detector fixed to an object T movable relative to the X-ray source 10, for example a surgical instrument or a catheter. In this case, the detection system 2 enables a physician or operator to locate a surgical instrument introduced into the patient's body in real time and in three dimensions. To this end, the following assumption is made: the rotation speed V of the support 20 is very high relative to the movement speed of the object T being tracked. For example, the detection element DT can be a probe with an outer diameter typically less than 800 microns, comprising a radioluminescent GaN transducer optically coupled to an optical fiber, wherein the optical fiber itself is connected by its other end to a photoelectric detection module operating in "photon counting" mode.

[0119] In one or more embodiments, the X-ray source 10 is a pulse source, which is configured to emit X-rays in an emission cycle consisting of two modes used alternately, one mode is an X-ray emission mode, and the other mode is an X-ray non-emission mode. Then, the detection element DT is configured to detect the X-rays passing through the slit in a manner synchronized with the X-ray emission cycle. In this case, in particular, the rotation speed of the support 20 can be selected so that the support 20 rotates one circle within the excitation duration of the pulse source (i.e., within the duration of the X-ray emission mode). The emission duration can last from a few milliseconds to tens of milliseconds. The angular velocity V of the support 20 is adjusted to 3000 revolutions per minute, and the emission time lasts for 20 milliseconds.

[0120] For example, the support 20 may be made of an X-ray scintillator material, which is configured to emit scintillation photons when the support 20 is exposed to an X-ray source. The scintillator material may be made of CdWO 4, LSO, LYSO and BGO or any other high atomic number material. The thickness of the support 20 may be between 0.5 mm and 4 mm, depending on the required X-ray attenuation. In this case, the detection system 2 further includes a photodiode PD, which is configured to detect scintillation photons and emit a photocurrent generated by the detected scintillation photons. An example of a photodiode PD that can be used is the optical switch OPL551 sold by Farnell. The detection of scintillation photons by the photodiode makes it possible to trigger the collection of X-rays passing through the slit 30 by the detection element DT. In other words, X-rays are only detected if the scintillation of the support 20 is detected. For example, this can be used to subtract the background level determined when the element DT is not irradiated (i.e., when the support is not scintillation) to improve the detection contrast and help select the detection threshold to reduce false detections.

[0121] In the above configuration, the processing unit 50 can use the photocurrent emitted by the photodiode to automatically feedback-control the rotational angular velocity V of the support relative to the duration of the emission mode of the pulse source. Therefore, the detection element DT detects X-rays only when the X-ray source 10 is in the X-ray emission mode, which makes it possible to avoid the noise that exists when the X-ray source 10 is not emitting.

[0122] Fig.10 An X-ray imaging system 3 is schematically shown. The X-ray imaging system 3 may implement an X-ray detection system 2 according to any of the embodiments described herein. Such an imaging system 3 is used to generate radiographic images, in particular to generate radiographic images of a portion of a patient's body. Such an imaging system 3 comprises a plurality of acquisition elements Mi forming an acquisition matrix M placed in an acquisition field of the imaging system 3. When the support 20 is chosen to have partial radiotransparency, each element Mi of the acquisition matrix M may acquire by integration the X-ray stream transmitted through the slit and / or through the support 20 when the support 20 of the collimator of the detection system is rotated around the axis Δ of the support 20. Thus, the image may be reconstructed in two different ways: by obtaining a fluoroscopic image after one or more rotations of the slit (radial scans), or by using a support whose radiopacity is adjusted, letting through enough X-rays to be able to reconstruct a possibly degraded image. As described herein, these two image acquisition modes in one imaging plane may be used in combination with a method for detecting the position of a detection element DT located upstream of another plane. The quality of the images obtained will depend inter alia on the number of rotations of the support used to acquire each image, the material used for the support and its thickness. By combining one of these image acquisition modes with a method for detecting the position of the detection element DT, the detection element DT can be localized in real time in the (possibly degraded) images.

[0123] Thus, the acquisition matrix M can acquire radiographic images based on the acquisitions respectively performed during a given period of time by the acquisition elements Mi constituting the acquisition matrix M. It should be noted that the rate of the imaging solution proposed here is not sufficient for monitoring surgical instruments (e.g., catheters), but enables the preoperative images to be updated slowly. An example of an acquisition matrix M can be the Pixium 3040 model from the company THALES, with dimensions of 293 mm×398 mm, a resolution of 1904 pixels×2586 pixels, and a pixel size of 154 microns.

[0124] exist Fig.10 In FIG. 3 , it can be seen that the imaging system 3 comprises a detection system as described above and an acquisition matrix M placed in an imaging plane downstream of the model body. It can be seen that the acquisition matrix M is illuminated by the X-ray flow that has passed through the model body made of PMMA.

[0125] In one or more embodiments, the X-ray imaging system 3 comprises a plane stop 21, which is placed between the X-ray source 10 and the support 20, and which defines a field of view, the projection FOV of which on the acquisition matrix M does not exceed the size of the acquisition matrix M. For example, for a square field FOV of 30 cm×30 cm and a magnification of 3 times, the plane stop 21 will consist of two pairs of "jaws" forming a square field of view of 10 cm×10 cm. Typically, the distance between the X-ray source 10 and the acquisition matrix M is equal to 100 centimeters, and the acquisition matrix M is placed behind the patient but at a relatively close distance. Typically, the distance between the X-ray source 10 and the support 20 is 40 cm. Typically, the distance between the X-ray source 10 and the plane stop 21 is 35 cm. Typically, the distance between the X-ray source 10 and the detection element DT introduced into the patient is 80 cm. Typically, the detector is rectangular in shape, and the stop is also rectangular. In these embodiments, the path that the X-rays pass through is in the following order: source-aperture-rotating single-slit collimator-patient-2D X-ray detector (e.g., pixel matrix), the patient has a catheter, the catheter is provided with a detection element DT, and the 2D X-ray detector is used to capture one or more images.

[0126] Such an imaging system 3 not only controls the radiation dose of the patient, but also combines the generation of radiographic images in real time with the three-dimensional positioning of surgical elements of the X-ray imaging system for medical procedures, such as a catheter inserted into the patient during a catheterization procedure.

[0127] Fig.11A plurality of successive angular positions of the support 20 and therefore of the slit 30 are shown, which are obtained by rotating the support 20 over time. Thus, the slit 30 generates a radiation scan of the projection FOV on the acquisition matrix M according to the intersection between the X-ray flow from the slit 30 and the projection FOV on the acquisition matrix M at each time.

[0128] When a pulse source is used, the pulse source is configured to emit X-rays in an emission cycle consisting of two modes used alternately, one mode is the X-ray emission mode, and the other mode is the X-ray non-emission mode, and the acquisition matrix M is configured to acquire radiographic images in a manner synchronized with the X-ray emission cycle.

[0129] In particular, in the case where the support 20 is made of an X-ray scintillator material and the support 20 can emit scintillation photons when the support 20 is exposed to an X-ray source, and in the case where the detection system further includes a photodiode PD that can detect the scintillation photons and emit a photocurrent generated by the detected scintillation photons, the detection of the scintillation photons by the photodiode makes it possible to trigger the acquisition of at least one X-ray image by the acquisition matrix M. Therefore, the acquisition of radiographic images by the acquisition matrix M is windowed, and the windows correspond to different X-ray emission modes of the X-ray source 10. Each radiographic image acquired by the acquisition matrix M originates from the accumulation of X-rays over multiple emission cycles of the X-ray source 10. This enables the acquisition matrix M to detect only those X-rays coming from the X-ray source 10 and avoid detecting any noise that can reduce the quality of the radiographic images acquired by the acquisition matrix M.

[0130] Furthermore, the processing unit can use the photocurrent emitted by the photodiode PD to automatically feedback control the rotational angular velocity V of the support relative to the duration of the pulse from the pulse source. This makes it possible to ensure that the support completes at least one rotation within the duration of the pulse without requiring any interconnection between the processing unit and the X-ray generation system.

[0131] Fig.12 3, which is a schematic diagram of an X-ray imaging method according to the invention. Fig.12From left to right in the figure, the miniaturized detection element DT is positioned at 12 mm, 7 mm and 4 mm from the rotation axis Δ, respectively. In each of the three images, a black disk can be seen in the center. This black disk is characteristic of the distance d at which the slit 30 on the support 20 is located. This black disk or dead zone is surrounded by a very bright halo corresponding to the position of the slit, at which the slit is tangential to the black disk: specifically, at these positions, the rotation speed of the support 20 is the slowest, having the effect of irradiating the slit 30 for a longer time. Outside this bright halo, the brightness decreases in the direction of the periphery of the support 20.

[0132] The invention thus has the advantage of being able to combine two modes of an X-ray imaging system 3: a mode for "real time" localization and tracking of an object (e.g. a surgical instrument in the body) and a "low rate" imaging mode, making it possible to produce radiographic images with a lower X-ray dose by virtue of the low radiotransparency of the collimation device according to the invention. Another advantage is the use of a simplified device (single slit collimator).

[0133] By optimizing the geometry of the slits in the main plane P of the support and in the thickness of the support 20, the collimation device 2, the detection system 2 and the imaging system 3 as well as the associated positioning and imaging methods can be improved to further reduce the radiation dose to the patient and the physician.

[0134] This reduction can be achieved, for example, by attenuating very bright halos visible at the periphery of dead zones present in images obtained by the imaging method according to the invention and described above.

[0135] One embodiment of a slit 30 for attenuating bright halos and reducing radiation dose may be to use a shallower slit 30, i.e., on portion 30a, maintaining the thickness of the radiopaque material near the rotation axis of the support 20, and a deeper slit 30, i.e., on portion 30b, maintaining or even cutting into the support 20, i.e., through the material of the support 20 near the edge of the support 20.

[0136] Another embodiment of the slit 30 for attenuating bright halos and reducing radiation dose may define the slit 30 as described in the present application, wherein the slit 30 deviates from the rotation axis Δ by a distance d in three regions: two slit segments 301 and 302 and a radiopaque (or less radio-transparent) central portion 303, the two slit segments 301 and 302 being separated from the tangent point of the slit 30 by a second distance d', and a circle with a radius d being centered on the projection of the rotation axis Δ of the support onto the support 20.

[0137] Fig.13 A collimation device having such a slit 30 is schematically shown. Fig.13, a support 20 in the form of a disk is shown. The support 20 comprises a slit 30 offset by a distance R relative to the axis of rotation Δ, the slit 30 consisting of two slit segments 301 and 302 and a central portion 303, each of the slit segments 301 and 302 being separated by a second distance dd' from the point of tangency of the slit 30. The two slit segments 301 and 302 exhibit partial radiotransparency. The central portion 303 exhibits zero radiotransparency.

[0138] In one embodiment of the collimating device, the main plane of the support comprising the slit may further comprise one or more holes or channels: these channels are used to calibrate the collimating device in an imaging system according to any of the embodiments described herein. The channels make it possible to determine a projection matrix from the main plane of the support to the image acquisition plane (also called image plane). Thus, by applying this projection matrix, the position of the detection element originally calculated in the main plane of the support of the collimating device 1 can be determined in the image plane.

[0139] This projection matrix collects information on the geometric position of the plane of the support relative to the source and the X-ray detector of the imaging system. To this end, before the stage of position search of the detection elements is carried out, at least one image is acquired in which not only the projection of the slit is shown, but also the projection of each channel, the projection of each channel being formed by the X-rays that have passed through the channel in question and reached the image plane.

[0140] The characteristics of the channels can be as follows. The diameter is chosen to avoid over-irradiation of the patient, while being sufficient to allow X-rays to pass through in order to reliably detect the projection of the channels in the image plane. For example, the diameter of the channels is of the same order of magnitude as the width of the slits. For the slits, the channels can be positioned at the edge of the plane of the support in order to obtain better calibration accuracy. The position of each of the channels in the main plane of the support of the collimator is known.

[0141] When the support comprises a plurality of channels, the channels must be distinguishable from each other. To this end, the channels may have different diameters or be positioned so that the resulting arrangement distinguishes the channels. Furthermore, the channels should not be aligned: for example, if the main plane of the support has four channels, these four channels should form a quadrilateral. Fig.14A An embodiment of a single slit 20 collimation device 1 having four channels 50A, 50B, 50C, 50D of different diameters is shown.

[0142] exist Fig. 14BIn another embodiment shown, the plane of the support containing the slit 20 contains a single channel 50E having the above-described characteristics. Since the plane is rotatable, the presence of at least three other channels can be simulated by rotating the collimator each time through a known angle and acquiring an image for each angle. This embodiment has many advantages. There are fewer channels in the plane and therefore fewer X-rays that can reach the patient during the phase of positioning the detection element. The problem of distinguishing the projection of the channels on the image plane no longer arises: each image is acquired after rotating the support of the collimator. Therefore, each new position of the channel in the main plane of the known support is associated with the projected position of the channel in the image plane. Since only the plane of the support rotates and no other elements move, the assembly can be calibrated.

[0143] In this context, the calibration method for determining the projection matrix from the plane of the support to the image acquisition plane can be the calibration method described in patent application FR3028039A1 or WO2016071645A1. In this calibration method, the position of the projection of at least N channels in the image plane is determined based on one or more acquired images. The intrinsic calibration matrix of the "imaging + collimator" system in the reference position and the projection position of the channel in the image plane of the reference position are obtained. Then, by matching each channel, the homography is calculated between the projection positions of the channel in the reference position and the measurement position. To this end, the following assumption is made: between the reference position and the measurement position, the "source + collimator" components are rigidly connected, so they do not move relative to each other. Only the image detector is enabled to move freely between the reference position and the measurement position relative to the "source + collimator" component. The number of channels N used for calibration must be sufficient to determine the homography. For example, there are at least 4 channels (N=4). In the case where the "source + collimator" component is not rigidly connected, other methods are used to project the position represented by the detection element in the plane of the support to the image plane. For example, the intrinsic calibration matrix of the imaging system at the measurement position is obtained by offline calibration using a known 3D test pattern and by assuming that the imaging system is mechanically reproducible within a known time interval. More details are given in patent application WO2016071645A1.

Claims

1. A collimation device (1) for an X-ray detection system, the collimation device (1) comprising: A collimator comprising a substantially planar support (20), the support being made of a material having partial or zero radiotransparency, the support (20) being rotatably movable about a rotation axis (Δ), the rotation axis passing through the support and being perpendicular to a first face of the support (20), the first face of the support being a plane of incidence for X-rays, referred to as a principal plane (P) of the support, The support (20) is provided with a single slit (30) on the first surface, the slit is completely transparent to X-rays, and the slit is configured to generate an X-ray flow when the collimator is exposed to the X-ray source (10), the slit (30) extends longitudinally in the main plane of the support along an axis at a non-zero distance from the rotation axis (Δ), and the slit (30) extends through the entire thickness of the support (20).

2. The collimation device (1) according to claim 1, wherein: The slit (30) has a projection of a rectangular or trapezoidal shape in the main plane (P) of the support.

3. An X-ray detection system (2), the detection system (2) comprising: - an X-ray source (10) configured to emit an X-ray beam; - A collimation device (1) according to any one of the preceding claims, placed to receive the X-ray beam in the plane of incidence of the support; - a drive device configured to rotate the support (20) of the collimation device at a fixed rotational angular velocity (V) around an axis of rotation (Δ) of the support (20); - at least one X-ray detection element, which is placed in a collection field opposite to the support (20) relative to the X-ray source (10) to collect X-rays when a portion of the X-ray beam that passes from the first face of the support through the slit (30) in the support (20) to the opposite face reaches the detection element in question during the rotation of the support.

4. The detection system (2) according to claim 3, in, A detection element (DT) from the at least one X-ray detection element is configured to detect X-rays passing through the slit (30) at two consecutive times when the support (20) rotates, a first time (t_α) corresponding to a first angular position (α) of the slit, and a second time (t_β) corresponding to a second angular position (β) of the slit (30), the first angular position and the second angular position defining an intersection point (C) in the main plane (P) of the support, the intersection point (C) corresponding to a projection position (PT) of the detection element (DT) in the main plane of the support (20); The detection system (2) comprises a processing unit (50) configured to determine a projection position (PT) of the detection element (DT) in the main plane (P) of the support as a function of the first angular position and the second angular position. 5 . The detection system according to claim 4 , the processing unit being configured to determine the first angular position and the second angular position based on the first time and the second time and the angular velocity of the support.

6. The detection system (2) according to claim 4, further comprising: - a second support (20b) fixed to the support (20) or forming an integral part of the support (20), the second support comprising a series of N windows angularly uniformly distributed around a circular periphery centered on the axis of rotation (Δ) of the support, the series of N windows comprising a reference window having a size different from the other windows, the other windows being indexed relative to the reference window, an optical fork provided with a transmitter and a receiver, the transmitter being configured to transmit a light wave, the receiver being configured to detect the light wave, the optical fork being configured to generate an electrical pulse when the receiver receives the light wave at any one of the windows passing between the transmitter and the receiver, The processing unit (50) is configured to determine the first angular position and the second angular position based on the index of two windows of the second support member (20b) generating the electric pulse, which is closest in time to the two consecutive times for which the detection element (DT) performs detection.

7. The detection system (2) according to any one of claims 4 to 6, wherein: The processing unit (50) is configured to: - In the case where the slit is rectangular in shape, the distance between the X-ray source (10) and a plane passing through the detection element (DT) and parallel to the main plane (P) of the support is determined based on the radiation duration of the detection element (DT), the rotation angular velocity (V) of the support, the distance between the X-ray source (10) and the support (20), the width (l) of the slit, and the distance between the intersection of the projection position (PT) in the main plane (P) of the support (20) and the rotation axis (Δ) of the support (20).

8. The detection system (2) according to any one of claims 4 to 6, wherein: - the X-ray source (10) is a pulse source, which is configured to emit X-rays in an emission cycle consisting of two modes used alternately, one mode is an X-ray emission mode, and the other mode is an X-ray non-emission mode, - the detection element (DT) is configured to detect the X-rays passing through the slit (30) in a manner synchronized with the emission period of the X-rays.

9. The detection system (2) according to claim 8, wherein: The support (20) is made of an X-ray scintillator material, and when the support is exposed to the X-ray source, the support (20) is capable of emitting scintillation photons. The detection system (2) further comprises a photodiode (PD) configured to detect scintillation photons and emit a photocurrent generated by the detected scintillation photons to trigger the detection element (DT) to detect and collect the X-rays passing through the slit (30).

10. The detection system (2) according to claim 9, wherein: The processing unit (50) is configured to use the photocurrent emitted by the photodiode (PD) to automatically feedback-control the rotational angular velocity (V) of the support relative to the duration of the pulse from the pulse source.

11. An X-ray imaging system (3), comprising: The detection system (2) according to any one of claims 4 to 10, comprising a photodiode (PD); A plurality of acquisition elements, the plurality of acquisition elements forming an acquisition matrix (M) placed in an acquisition field of the imaging system, each element in the acquisition matrix (M) being configured to acquire X-ray flow accumulation when the support (20) of the collimator of the detection system rotates around the rotation axis (Δ) of the support, the acquisition matrix (M) being configured to acquire radiographic images based on acquisitions respectively performed by the acquisition elements constituting the acquisition matrix (M) during a given time period.

12. The X-ray imaging system (3) according to claim 11, further comprising: A plane aperture (21) is placed between the X-ray source (10) and the support (20) and defines a field of view, the projection of which on the acquisition matrix (M) does not exceed the size of the acquisition matrix (M).

13. The X-ray imaging system (3) according to claim 11 or 12, which implements the detection system (2) according to claim 8, wherein: The acquisition matrix (M) is configured to acquire radiographic images in a manner synchronized with an emission cycle of X-rays.

14. The X-ray imaging system (3) according to claim 11 or 12, which implements the detection system (2) according to claim 9, wherein: The X-ray source (10) is a pulse source, which is configured to emit X-rays in an emission cycle consisting of two modes used alternately, one mode is an X-ray emission mode, and the other mode is an X-ray non-emission mode, and wherein the detection element (DT) is configured to detect the X-rays passing through the slit (30) in a manner synchronized with the X-ray emission cycle, wherein the processing unit (50) is configured to use the photocurrent emitted by the photodiode (PD) to automatically feedback control the rotational angular velocity (V) of the support relative to the duration of the pulse from the pulse source, wherein the photodiode (PD) is configured to detect scintillation photons and emit the photocurrent generated by the detected scintillation photons to trigger the acquisition matrix (M) to acquire at least one radiographic image.

15. The X-ray imaging system (3) according to claim 14, which implements the detection system (2) according to claim 10, wherein: The processing unit (50) is configured to use the photocurrent emitted by the photodiode (PD) to automatically feedback-control the rotational angular velocity (V) of the support relative to the duration of the pulse from the pulse source.

16. A method for positioning a detection element (DT) of an X-ray detection system, the X-ray detection system being an X-ray detection system according to any one of claims 4 to 10, the method comprising the following steps: - rotating the support (20) of the collimation device (1) around its axis of rotation (Δ) at a fixed angular velocity (V); - during the rotation of the support (20), exposing the support (20) to an X-ray beam from the X-ray source (10); - the detection element (DT) detects X-rays passing through the slit (30) in the support at two consecutive times, a first time (t_α) corresponding to a first angular position (α) of the slit and a second time (t_β) corresponding to a second angular position (β) of the slit, - the processing unit (50) determines the projection position (PT) of the detection element (DT) in the main plane (P) of the support (20) based on the first angular position and the second angular position.

17. Method for positioning a detection element (DT) of an X-ray detection system according to claim 16, wherein: The first angular position and the second angular position are determined based on the first time and the second time and the angular velocity of the support.

18. A method for positioning a detection element (DT) of an X-ray detection system, the X-ray detection system being an X-ray detection system according to claim 6, the method comprising the following steps: - rotating the support (20) of the collimation device (1) around its axis of rotation (Δ) at a fixed angular velocity (V); - during the rotation of the support (20), exposing the assembly formed by the support (20) and the second support (20b) to an X-ray beam from the X-ray source (10); - detecting an electrical pulse generated when said receiver receives said light wave at any of the windows passing between said transmitter and said receiver of said optical fork; - the detection element (DT) detects X-rays passing through the slit (30) in the support (20) for a first angular position (α) of the second support (20b) and a second angular position (β) of the second support (20b), - the processing unit (50) determines the projected position (PT) of the support in the main plane based on the first angular position and the second angular position, The first angular position and the second angular position are obtained based on the indexes of the two windows generating the electrical pulses which are closest in time to the two consecutive times for which the detection element (DT) performs detection.

19. Method for positioning a detection element (DT) of an X-ray detection system according to claim 18, in case the X-ray detection system (2) is a detection system (2) according to claim 10, wherein: The X-ray detection system (2) includes a photodiode (PD), wherein the X-ray source (10) is a pulse source, the pulse source is configured to emit X-rays in an emission cycle consisting of two modes used alternately, one mode is an X-ray emission mode, and the other mode is an X-ray non-emission mode, and the detection element (DT) is configured to detect the X-rays passing through the slit (30) in a manner synchronized with the X-ray emission cycle, and wherein the processing unit (50) is configured to use the photocurrent emitted by the photodiode (PD) to automatically feedback control the rotational angular velocity (V) of the support relative to the duration of the pulse from the pulse source, and use the photocurrent emitted by the photodiode (PD) to automatically feedback control the rotational angular velocity (V) of the support relative to the duration of the pulse from the pulse source.

20. A method for positioning a detection element (DT) of an X-ray detection system according to any one of claims 16 to 19, the method comprising the following steps: The processing unit (50) determines the distance between the plane containing the detection element (DT) and parallel to the main plane (P) of the support (20) and the X-ray source (10) based on the radiation duration (tirr) of the detection element (DT), the rotational angular velocity (V) of the support, the distance (D) between the X-ray source (10) and the support (20), the width (l) of the slit, and the distance r between the intersection of the projection position (PT) in the main plane (P) of the support (20) and the rotation axis (Δ) of the support (20).

21. An X-ray imaging method, the imaging method being implemented by the X-ray imaging system (3) according to claim 11 or 12, the imaging method comprising the following steps: - rotating the support (20) of the collimation device (1) of the imaging system (3) at a fixed rotational angular velocity (V) around the rotation axis (Δ) of the support; - during the rotation of the support (20), exposing the support (20) to an X-ray beam from the X-ray source (10); - the acquisition elements of the acquisition matrix detect X-rays during the rotation of the support (20); - Acquisition of a radiographic image based on the detections respectively performed by said acquisition elements of said acquisition matrix (M) during a given period of time.

22. An X-ray imaging method, the imaging method being implemented by the X-ray imaging system (3) according to claim 14, the imaging method comprising the following steps: - rotating the support (20) of the collimation device (1) of the imaging system (3) at a fixed rotational angular velocity (V) around the rotation axis (Δ) of the support; - during the rotation of the support (20), exposing the support (20) to an X-ray beam from the X-ray source (10); - the acquisition elements of the acquisition matrix detect X-rays during the rotation of the support (20); - the support (20) emits scintillation photons; - the photodiode (PD) detects the scintillation photons, - said photodiode emits a photocurrent generated by the detected scintillation photons to trigger the acquisition of at least one radiographic image by said acquisition matrix (M), - Acquisition of a radiographic image based on the detections respectively performed by said acquisition elements of said acquisition matrix (M) during a given period of time.

23. The X-ray imaging method according to claim 22, wherein the imaging method is implemented by the X-ray imaging system (3) according to claim 15, wherein: The processing unit (50) uses the photocurrent emitted by the photodiode (PD) to automatically feedback control the rotational angular velocity (V) of the support relative to the duration of the pulse of the pulse source, so that the acquisition of the radiographic image based on the detection performed respectively by the acquisition elements of the acquisition matrix (M) is temporally windowed in the X-ray emission mode of the emission period of the pulse source.

Images