Circular double-arch radiology device
A static CT scanner with fixed ionizing radiation sources and detectors improves spatial resolution and reduces mechanical complexity by using compact cold cathode sources and alternating focal point distributions, addressing the limitations of rotating systems.
Patent Information
- Application Number
- FR2024015443
- Authority / Receiving Office
- FR · FR
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2026-07-03
AI Technical Summary
Existing computed tomography (CT) scanners are bulky, mechanically complex, and prone to failures due to drive chain wear, requiring maintenance, and their spatial resolution is limited by the angular spacing of rotating X-ray sources, which can be improved only at the cost of increased system size or power.
A static radiology device with fixed ionizing radiation sources and detectors arranged in alternating groups around a cylindrical surface, allowing for improved spatial resolution without rotation, using compact cold cathode sources and alternating focal point distributions to reduce angular spacing.
The solution provides a compact, maintenance-free CT scanner with enhanced spatial resolution by reducing angular spacing between sources, maintaining system size and power efficiency.
Smart Images
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Abstract
Description
Title of the invention: Circular double-arch radiology device
[0001] The present invention relates to a radiology device. The invention can be implemented particularly in the medical field, in industry for performing non-destructive testing, and in security for detecting hazardous objects or materials. The invention is particularly useful in computed tomography (CT) scanning.
[0002] Computed tomography, also known as computed tomography, employs a system equipped with an X-ray tube that emits a collimated fan-shaped beam. The X-ray tube is connected to a detector positioned opposite the beam. The X-ray tube, or generator, and the detector rotate around a table that holds a patient or object to be imaged. During rotation, the X-ray tube emits several beams at regular intervals. With each rotation, the table advances along the axis of rotation of the tube and detector by a small offset corresponding to the thickness of a slice of the patient or object. Computer processing allows the reconstruction of 2D slices or 3D volumes of the anatomical structures of the patient or object from the sinograms captured by the detector. This system is known as a "CT scanner." "CT" is the acronym for "Computer Tomography."
[0003] The mechanical equipment used to rotate the tube and detector is bulky and heavy. Furthermore, the rotation system requires maintenance of the drive chain to keep the system operational. The system may experience failures related in particular to mechanical wear of the drive chain and the rotary contactor that enables the transfer of information between the rotating and stationary parts of the radiology device.
[0004] The invention generally aims to provide a radiology device capable of performing computed tomography examinations without using a tube and detector rotating together. The invention makes it possible to implement a static, non-rotating system comprising a plurality of ionizing radiation sources arranged opposite one or more detectors.
[0005] The spatial resolution of a rotating generator radiology device can be adapted according to the angular spacing defined between the successive generation of different fan-shaped X-ray beams during the rotation of the X-ray tube. This angular spacing has no lower limit a priori, except for the time required for these multiple generations, a time during which the patient may move. In contrast, in a static system equipped with numerous angularly distributed X-ray sources Around a region of interest, spatial resolution is limited by the spacing between two adjacent sources. To increase spatial resolution, it would be possible to increase the distance of the different sources from the region of interest, thus reducing the angular distance between two adjacent sources. In other words, by arranging the sources on a circular arc around the region of interest, for the same volume occupied by each source, increasing the radius of the circular arc reduces the angular spacing between the sources. However, this increase in distance requires increasing the power of each source and tends to increase the volume of the radiology system, which is undesirable.
[0006] The invention aims to provide a compact static radiology device in which spatial resolution is improved.
[0007] To this end, the invention relates to a radiology device comprising a mobile support in translation along an axis of translation relative to a frame of the device, the support being intended to carry an object to be imaged, an ionizing ray generator and a detector configured to detect the rays emitted by the generator, the generator and the detector being fixed together and facing each other,
[0008] • the detector being formed of sensitive elements distributed over a portion of surface cylindrical detector, the translation axis forming a generatrix of the cylindrical surface portion, the cylindrical surface portion extending between two detector planes perpendicular to the translation axis,
[0009] • the generator comprising several sources of ionizing radiation of which we consider that they each emit from a focal point, each of the sources emitting a substantially flat, fan-shaped beam of ionizing rays,
[0010] • the sources being distributed into at least two groups, in each of the groups, the focal points of the different sources of the group under consideration being distributed over a portion of the cylindrical surface of the group of sources, the translation axis forming a generatrix of the portion of the cylindrical surface, two of the groups being arranged outside an area between the two planes of the detector, on one side for one of the groups and on the other side for the other group,
[0011] • in each of the two groups arranged outside the area between the two detector planes, the focal points of the different sources of the group considered being distributed along at least one curve extending in a plane perpendicular to the axis of translation, along each curve, an abscissa of each of the focal points located there is defined,
[0012] • in the two groups arranged outside the area between the two detector planes, the abscissas of the focal points are matched and alternated from one of the two groups to the other.
[0013] The curves are advantageously arcs of circles centered on a point located on the axis of translation.
[0014] In each of the groups, the focal points of the different sources of the group considered are advantageously distributed along at least two curves, each extending in a plane perpendicular to the axis of translation; along each curve, an abscissa of each of the focal points located there is defined; in the same group, the abscissas of the focal points distributed on two of the curves are matched and alternated from one curve to the other.
[0015] In each of the two groups, the abscissas of the focal points advantageously occupy an angular sector around the translation axis of at least 180°.
[0016] The detector can occupy an angular sector of less than 360°. The generator advantageously comprises, in an angular sector left free by the detector, a third group of sources whose focal points are distributed over a portion of cylindrical surface located in the area between the two planes of the detector.
[0017] The different groups are advantageously configured to allow the emission of ionizing radiation at different energy levels from one group to another.
[0018] The invention will be better understood and other advantages will become apparent upon reading the detailed description of embodiments given by way of example, a description illustrated by the accompanying drawing in which:
[0019] [Fig-1] [Fig.1] schematically represents an example of a radiology device according to the invention;
[0020] [Fig.2] [Fig.2] represents, in cross-section, the radiology device of [Fig.1];
[0021] [Fig.3] [Fig.3] represents, in a flat view, the position of different sources of ionizing rays from the radiology device of the [Fig.1];
[0022] [Fig.4] [Fig.4] represents in perspective a variant of a radiology device;
[0023] [Fig. 5] [Fig. 5] represents, in a flat view, the position of different sources of ionizing radiation from the radiology device of [Fig.4].
[0024] For the sake of clarity, the same elements will bear the same references in the different figures.
[0025] Figure 1 represents a radiology device 10 capable of performing computed tomography examinations. The device 10 comprises a frame 12 and a support 14 that is movable in translation relative to the frame 12. The support 14 is in the form of a platform. The support 14 is movable along a translational axis Z relative to the frame 12. A rectangular area of interest 18 is defined above the support 14. The area of interest 18 is intended to receive an object to be imaged. Any other shape of area of interest is also possible, in particular an area with a circular cross-section. The shape of the support 14 can then be adapted accordingly. The device 10 comprises an ionizing radiation generator 20 and a detector 22. The ionizing radiation can be X-rays or gamma rays. The generator 20 and the detector 22 are linked and both are fixed to the frame 12. The detector 22 is configured to detect the rays emitted by the generator 20. The generator 20 and the detector 22 are positioned opposite each other so that the detector 22 can receive the ionizing rays emitted by the generator 20.
[0026] To avoid rotating the generator 20 and the detector 22 around the Z-axis, the generator 20 comprises several static sources 24 of ionizing radiation distributed around the Z-axis. The various sources 24 emit in the direction of the detector 22. The emission from the sources 24 passes through the region of interest 18 before reaching the detector 22. For simplicity, each of the sources 24 is considered to have a focal point from which a beam of ionizing rays extends. In the various figures, the focal points are also marked with the symbol 24. Each of the sources 24 emits a substantially flat, fan-shaped beam of ionizing rays 26. This beam shape is obtained, for example, by means of a collimator positioned near the focal point of each source. To avoid cluttering [Fig. 1], only one source 24 and the beam 26 emanating from it are shown.
[0027] The detector 22 is formed of sensitive elements distributed over a portion of cylindrical surface 28 of the detector 22. The translation axis Z forms a generatrix of the portion of cylindrical surface 28, the portion of cylindrical surface 28 extending between two planes 30 and 32 of the detector 22. The two planes 30 and 32 are perpendicular to the translation axis Z. In other words, in an orthogonal XYZ frame, represented in [Fig. 1], the planes 30 and 32 are parallel to the XY plane of the frame.
[0028] Figure 2 shows the radiology device 10 in cross-section in the YZ plane. The sources 24 are distributed into two groups 34 and 36. In each of the groups 34 and 36, the focal points of the different sources in the group are distributed over a portion of a cylindrical surface, 38 and 40 respectively. The generatrices of the cylindrical surface portions 38 and 40 are parallel to the Z-axis. Group 34 is located outside an area between the two planes 30 and 32, on the side of plane 30, and group 36 is located outside the area between the two planes 30 and 32, on the side of plane 32.
[0029] The sources 24 are advantageously compact, as described, for example, in patent application published under No. WO 2019 / 011980 A1 and filed in the name of the applicant. Each source 24 may comprise, within a vacuum enclosure, one or more cathodes emitting an electron beam, an anode having one or more targets bombarded by the electron beam(s) generated by the cathode(s) and emitting one or more beams of ionizing radiation. Each cathode advantageously emits its electron beam by field effect in the direction of the target. This type of cathode is known as a cold cathode as opposed to hot cathodes also called: thermionic cathodes.
[0030] The advantage of implementing compact cold cathode sources is to allow the focal points of the different sources to be brought closer together 24. The approach is particularly evident in a configuration where several cathodes are arranged in a vacuum chamber.
[0031] Indeed, in conventional computed tomography, where the generator and detector rotate around the translation axis, it is possible to acquire as many images as desired during rotation in order to obtain sufficient data for reconstructing a two- or three-dimensional image. In the invention, by bringing the sources 24 closer together, it is possible to obtain sufficient data without rotating the generator around the Z-axis. However, it is possible to integrate into the radiology device a mechanism allowing rotation, around the Z-axis, of either the generator, the detector, or both in combination relative to the frame 12. This rotation is desirable, for example, if the generator does not cover an angular sector of at least 180° around the Z-axis. The rotation may cover only a fraction of a turn around the Z-axis.However, it remains advantageous to create a radiology device in which the generator 20 and the detector 22 are fixed relative to the frame 12 of the device 10. For this, the sources 24 of the generator 20 and the detector 22 advantageously cover an angular sector between 180° and 270° around the Z axis.
[0032] Generally, a cylindrical surface is formed by a generatrix based on a curve, which can be arbitrary. For the cylindrical surface portions 38 and 40, the generatrices are parallel to the Z-axis, and the curves on which the generatrices are based can be arcs of circles extending in planes perpendicular to the Z-axis and whose respective centers lie on the Z-axis. Arranging the focal points of the different sources 24 on such an arc of a circle makes it possible to obtain good homogeneity of illumination of the area of interest between the fan-shaped beams from the different sources. To facilitate the realization of each of the generator groups, it is possible to arrange the focal points of the different sources 24 on non-circular curves that remain close to arcs of circles.For example, it is possible to implement polygonal curves, advantageously regular and centered on the Z-axis. Along each edge of the polygonal curve, the focal points are aligned, which, for example, facilitates the fabrication of the sources. It is also possible to provide a common anode for several aligned sources. Thus, device 10 can have as many anodes as there are edges of the polygon. The cathodes of each source remain, of course, separate to allow independent control of each cathode. It is... particularly useful to control each source sequentially 24. It is understood that the invention can be implemented for other non-circular curve shapes.
[0033] Figure 3 represents, for each of the groups 34 and 36, a curve, respectively 44 and 46, along which the focal points of the different sources in the group under consideration are arranged. In practice, the focusing can be in the form of spots. For the purposes of this invention, the center of the spot is considered the focal point. The curves 44 and 46 each extend in a plane perpendicular to the Z-axis. An abscissa is defined for each focal point along the curve it occupies. The abscissas can be defined angularly around the Z-axis or linearly along the curve under consideration. The abscissas of the two curves 44 and 46 are correlated.
[0034] To better understand the invention, [Fig. 3] represents curves 44 and 46 in a flat plane. In other words, for the example of curves 44 and 46 in the form of circular arcs, the curves are brought into the plane of [Fig. 3]. In group 34, the focal points are numbered in order of their increasing abscissa: 34-1 to 34-7. For a current focal point 34-i, i represents the rank of the focal point. Similarly, the focal points of group 36 are numbered from 36-1 to 36-7. The abscissas of the focal points of the two groups are aligned, for example, parallel to the Z-axis. In other words, from a common origin for both groups, defined in a plane containing the Z-axis, the abscissas increase in the same angular direction for both groups.
[0035] In [Fig. 3], for the sake of clarity, only seven focal points are shown per group. It is understood that the invention can be implemented regardless of the number of focal points per group. In practice, a radiology device may comprise approximately one hundred sources per group, the sources being distributed over the angular sector covered around the Z-axis. According to the invention, the abscissas of the focal points alternate from group 34 to group 36. In other words, in ascending order of magnitude, one finds a focal point from group 34 followed by a focal point from group 36 followed in turn by a focal point from group 34, and so on for all the focal points of both groups 34 and 36.
[0036] In [Fig. 3], the sources of the same group are aligned on the same curve extending in a plane perpendicular to the translation axis Z. Thus, for the same volume occupied by each source, the angular spacing around the translation axis Z, between two sources with consecutive abscissas, one belonging to group 34 and the next to group 36, can be halved compared to the angular spacing between two consecutive sources of the same group. Compared to the implementation of a single group, Arranging the sources in two groups with alternating abscissas allows the angular step between two sources with consecutive abscissas to be halved, thus improving the spatial resolution of the device.
[0037] Figures 4 and 5 illustrate a variant of radiology device 50 making it possible to improve the spatial resolution of the device by further reducing the angular step between two sources of consecutive abscissa.
[0038] In the device 50, there is the detector 22 arranged between the two planes 30 and 32 and two groups of sources 54 and 56. As before, group 54 is arranged outside an area between the two planes 30 and 32, on the side of plane 30 and group 56 is arranged outside the area between the two planes 30 and 32, on the side of plane 32.
[0039] Each group comprises two curves: 58 and 60 for group 54, and 62 and 64 for group 56. Curves 58 to 64 each extend in a plane perpendicular to the translation axis Z. As before, along each curve, an abscissa of each of the focal points 24 is defined. Between the different curves 58 to 64, the abscissas are correlated. Between two curves of the same group, the abscissas of the focal points alternate from one curve to the other.
[0040] Thus, combined with the alternation of the abscissas of the focal points between the two groups 54 and 56, in the same way as the alternation between the two groups 34 and 36, we obtain an alternation on the four curves. In [Fig. 5], we thus find, in ascending abscissa order, a focal point 58-1 located on curve 58 followed by a focal point 64-1 located on curve 64, followed by a focal point 60-1 located on curve 60, followed by a focal point 62-1 located on curve 62, followed by a focal point 58-2 located on curve 58 and so on, following the same alternation of a focal point in the same order of the curves: 58, 64, 60 and 62. Such an alternation makes it possible to halve the angular step between two sources of consecutive abscissa compared to the variant shown in Figures 1 to 3.
[0041] It is of course possible to provide, in each group, more than two parallel curves on which focal points of the different sources 24 are located, respecting an alternation similar to that described previously.
[0042] As previously seen, the sources 24 of the generator 20 and the detector 22 advantageously occupy an angular sector less than 360°, for example between 180° and 270°. Between the planes 30 and 32, the detector 22 thus leaves a free angular sector in which it is possible to place a third group 70 of source 24. As with the other groups, the focal points of the different sources can have abscissas alternating with the abscissas of the other groups.
[0043] The construction of a generator 20 having groups of sources arranged at a distance from each other, in particular groups 34 and 36 in the variant shown in [Fig. 2] or groups 54 and 56 in the variant shown in [Fig. 4], makes it possible to supply them with different voltages. More precisely, the energy of the emitted X-ray photons depends primarily on the potential difference between the cathode and the target in question. A group of sources can comprise, as mentioned above, several cathodes in the same vacuum chamber, to which it is advantageous to apply the same voltage in order to facilitate the electrical isolation between neighboring cathodes. Consequently, if it is desired to construct a generator capable of emitting X-ray photons at different energies, it is advantageous to assign the different energy levels to different groups.In such a generator, it remains possible, of course, to apply the same potential difference to all groups.
[0044] Within the same group, creating a single vacuum enclosure for all the sources in the group can be challenging. Within this group, it is possible to juxtapose several separate vacuum enclosures, each on its own angular sector.
Claims
1. Demands Radiology device comprising a support (14) movable in translation along an axis of translation (Z) relative to a frame (12) of the device (10), the support (14) being intended to carry an object to be imaged, an ionizing ray generator (20) and a detector (22) configured to detect the rays emitted by the generator (20), the generator (20) and the detector (22) being fixed together and facing each other, • the detector (22) being formed of sensitive elements distributed over a portion of the cylindrical surface of the detector, the axis of translation forming a generatrix of the portion of cylindrical surface, the portion of cylindrical surface extending between two planes of the detector perpendicular to the axis of translation, • the generator (20) comprising several sources (24) of ionizing rays, each of which is considered to emit from a focal point, each of the sources (24) emitting a substantially flat, fan-shaped beam of ionizing rays (26), • the sources (24) being distributed into at least two groups (34, 36; 54, 56; 70), in each of the groups, the focal points of the different sources of the group considered being distributed over a portion of cylindrical surface (38, 40) of the group of sources, the translation axis (Z) forming a generatrix of the portion of cylindrical surface (38, 40), two of the groups being arranged outside an area between the two planes (30, 32) of the detector (22) on one side for one of the groups and on the other side for the other group, • in each of the two groups (34, 36; 54, 56) arranged outside the area between the two planes (30, 32) of the detector (22), the focal points of the different sources of the group considered being distributed along at least one curve (44, 46; 58, 60, 62, 64) extending in a plane perpendicular to the translation axis (Z), along each curve, an abscissa of each of the focal points located there is defined, • in the two groups (34, 36; 54, 56) arranged outside the area between the two planes (30, 32) of the detector (22), the abscissas of the focal points are matched and alternated from one of the two groups to the other.
2. Radiology device according to claim 1, wherein the curves are arcs of circles centered on a point located on the translation axis (Z).
3. Radiology device according to any one of the preceding claims, wherein in each of the groups (54, 56), the focal points of the different sources (24) of the group considered are distributed along at least two curves (58, 60, 62, 64) each extending in a plane perpendicular to the axis of translation (Z), along each curve an abscissa of each of the focal points located therein is defined, in the same group, the abscissas of the focal points distributed over two of the curves are matched and are alternated from one curve to the other.
4. Radiology device according to any one of the preceding claims, wherein in each of the two groups (34, 36; 54, 56), the abscissas of the focal points occupy an angular sector around the translation axis (Z) of at least 180°.
5. Radiology device according to any one of the preceding claims, wherein the detector (22) occupies an angular sector less than 360°, wherein the generator comprises, in an angular sector left free by the detector (22), a third group (70) of sources whose focal points are distributed over a portion of cylindrical surface located in the area between the two planes (31, 32) of the detector (22).
6. Radiology device according to any one of the preceding claims, wherein the different groups (34, 36; 54, 56; 70) are configured to permit the emission of ionizing rays at different energy levels from one group to another.