Radiation detector structure

Abstract

To provide a radiation detector structure.SOLUTION: A portable radiation cassette 10 is provided. The portable radiation cassette 10 includes a scintillator 20, a photosensitive slab 30, the scintillator 20 and the photosensitive slab 30 forming a panel 40 and the panel 40 including a front surface 410 intended to receive an incident X ray and a rear surface 420 facing the front surface 410, an electronic circuit board 50, and a mechanical protective housing 60 having the panel 40 and the electronic circuit board 50 disposed thereon and including an upper surface 610 and a bottom surface 620. In the portable radiation cassette 10, the upper surface 610 of the mechanical protective housing 60 includes a first layer 611 of a rigid material, a second layer 612 of a rigid material in contact with the front surface 410 of the panel 40, and a layer 613 of a bubble material disposed between the first layer 611 and the second layer 612 of the rigid material.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention falls within the field of imaging. The present invention may be applied to any type of imager (particularly X-ray, visible, and infrared imagers). The present invention will be described herein within the field of X-ray medical imaging as an example and without loss of applicability to other imaging fields. The present invention relates to a portable radiation cassette, and more particularly to an innovative radiation cassette structure that enhances the protection of the cassette against drops, impacts from external objects, local or distributed pressures, and any stresses.

Background Art

[0002] In the past, radiation systems were bulky and thus mostly immobile. It was necessary to position an object relative to the system to obtain a desired image. With the advent of solid-state detectors, the detectors have become less bulky, and thus it has become possible to move the detector relative to an object that remains fixed. With regard to medical radiation, digital detectors are now likely to be manufactured in the form of a mobile cassette that is placed close to a patient when an image is needed, where the patient's health condition prevents the patient from moving to a room secured for radiation.

[0003] A digital radiation cassette is substantially composed of at least one scintillator whose role is to emit visible light by the action of X-rays, a matrix of photodiodes (hereinafter referred to as a "slab" in this specification) manufactured on a substrate usually made of glass, which converts the optical signal emitted by the scintillator into electric charges, and one or more electronic circuit boards that read out these electric charges and convert them into a visible digital image.

[0004] The need for flexibility and responsiveness in the use of this type of equipment led manufacturers to propose portable digital radiation cassettes. These portable cassettes then need to balance extreme resistance to external aggression with reduced weight and size. Indeed, these portable cassettes may be subjected to drops, impacts from external objects, localized or distributed pressure loads, and bending stresses when the patient's weight is placed on an unevenly supported detector, both during their handling and throughout their lifespan. For this reason, the mechanical structure of the detector must ensure maximum protection of vulnerable elements, such as the scintillator, slab, and electronic circuit board.

[0005] In the traditional design of a portable radiation cassette, the scintillator is accompanied by a slab to form a subassembly called a panel. This panel is held against a base that provides rigidity and mechanical support to the panel. Finally, this panel is equipped with one or more electronic circuit boards before being inserted into the housing. The thickness of this housing (particularly the thickness of the front of the housing facing the X-ray source) is usually limited to limit the overall weight of the portable cassette and to ensure low absorption of X-rays passing through the portable cassette.

[0006] Figure 1 shows a cross-sectional view of a conventional portable radiation cassette structure. Conventionally, portable radiation cassette 1 includes the following: -Scintillator 2, which can convert incident X-rays into optical signals. - A photosensitive slab 3 capable of converting the optical signal emitted by the scintillator 2 after the conversion of X-rays into an electric charge. The scintillator 2 and the photosensitive slab 3 form a panel 4. The panel 4 includes a front surface 41 intended to receive incident X-rays according to the incident X-ray direction Z, a rear surface 42 opposite the front surface 41, and two transverse edges 43 (in the cross-sectional view). - Electronic circuit board 5 that guarantees the conversion of electric charge into a digital image. - A mechanical protective housing 6 on which the panel 4 and the electronic circuit board 5 are arranged, the mechanical protective housing 6 including an upper surface 61 on which incident X-rays are projected, a bottom surface 62 facing the upper surface 61, and two side surfaces 63 (in the cross-sectional view).

[0007] The portable radiation cassette 1 also includes two fixed supports 7 positioned inside the housing 6, each fixed support 7 resting in contact with the side surface 63 of the housing. The two fixed supports 7 form a kind of base for panel 4.

[0008] The panel is held against the side surface 63 of the housing 6 at its lateral edge 43 by using a fixed support 7. Therefore, there is at least one cavity 64 inside the housing 6, defining the empty space between the front surface 41 of the panel 4 and the top surface 61 of the housing 6. Optionally, there may also be a second empty space between the rear surface 42 of the panel 4 and the bottom surface 62 of the housing 6, which may be partially filled by the electronic circuit board 5.

[0009] Next, the flexible foam 8 is inserted into the cavity 64 to completely fill the cavity 64 and to make physical contact with the front surface 41 of the panel 4 on one side and the top surface 61 of the housing 6 on the other side. Since the ISO 4090 standard is restrictive regarding the dimensions of the portable cassette, the flexible foam 8 needs to be extremely malleable. This flexible foam 8 provides insulation against impact in the direction of X-ray incidence Z.

[0010] Therefore, the base formed by the fixed support 7 provides rigidity in the event of the portable cassette being dropped or flexed, and prevents excessive deformation of the panel 4, while the soft foam 8 of the housing 6 allows the panel 4 to be protected from impact. Finally, the combined rigidity of the housing 6 (with the soft foam 8) and the base prevents any significant deterioration in the event of pressure on the cassette.

[0011] Nevertheless, the thickness constraints on the housing, and in particular the adherence to the ISO 4090 standard limiting this dimension to 15 millimeters, prevent the provision of each of these parts (i.e., the base, housing 6, and flexible foam 8) at the thickness that would be desirable to fully fulfill their functions.

[0012] For this reason, it was found that the portable cassette 1, which utilizes state-of-the-art technology as shown in Figure 1, is not as robust as desired. [Overview of the project] [Problems that the invention aims to solve]

[0013] The present invention aims to mitigate all or some of the problems cited above by proposing an innovative portable radiation cassette structure that enhances its rigidity, ensures greater resistance to deformation, and more effectively protects the fragile elements contained within the portable radiation cassette. [Means for solving the problem]

[0014] Therefore, the subject of this invention is a portable radiation cassette comprising the following: - A scintillator that can convert incident X-rays into optical signals. - A photosensitive slab capable of converting an optical signal emitted by a scintillator into an electric charge, wherein the scintillator and the photosensitive slab form a panel, the panel having a front surface intended to receive incident X-rays and a rear surface opposite the front surface, - An electronic circuit board that guarantees the conversion of electric charge into a digital image. - A mechanical protective enclosure for which panels and electronic circuit boards are arranged, including a top surface and a bottom surface.

[0015] The portable radiation cassette is characterized in that the top surface of the mechanical protective housing includes the following: - The first layer of rigid material, - A second layer of rigid material that contacts the front surface of the panel, - A layer of cellular material placed between the first layer of rigid material and the second layer of rigid material.

[0016] According to one aspect of the present invention, the layer of cellular material is made of cellular material.

[0017] According to one aspect of the present invention, the layer of the foam material includes a laminate of at least partially hollow tubes that extend substantially perpendicular to the front face of the panel.

[0018] According to one aspect of the present invention, the layer of the foam material includes a number of beads.

[0019] According to one aspect of the present invention, the beads are hollow.

[0020] According to one aspect of the present invention, the second layer of the rigid material is adhered to the front face of the panel.

[0021] According to one aspect of the present invention, the layer of the foam material is defined by a third thickness, and the first and second layers of the rigid material are defined by a first thickness and a second thickness respectively, and the first thickness and the second thickness are smaller than the third thickness of the layer of the foam material.

[0022] According to one aspect of the present invention, the layer of the foam material is composed of an organic composite.

[0023] According to one aspect of the present invention, the first and / or second layer of the rigid material is composed of aluminum and / or magnesium and / or carbon or a mineral organic fiber composite.

[0024] According to one aspect of the present invention, the portable radiation cassette includes an anti-backscatter protection film disposed on the rear face of the panel, and the anti-backscatter protection film is preferably composed of at least one material with a high atomic mass.

[0025] According to one aspect of the present invention, the portable radiation cassette includes a heat insulation layer positioned between the electronic circuit board and the rear face of the panel.

[0026] The present invention is better understood by reading the detailed description of one embodiment shown by the accompanying drawings and given as an example, and other advantages will become apparent.

Brief Description of the Drawings

[0027] [Figure 1] This diagram schematically shows a cross-sectional view of a portable digital cassette structure known from conventional technology. [Figure 2] A schematic representation of the portable digital cassette structure according to the present invention is shown. [Figure 3] This diagram schematically shows the top view of the casing of the portable digital cassette according to the present invention. [Figure 4] This diagram schematically shows an exploded view of the top surface of the casing of a portable digital cassette according to a modified embodiment of the present invention. [Modes for carrying out the invention]

[0028] For clarity, the same element will have the same reference numeral in various drawings.

[0029] Figure 2 schematically represents the portable digital cassette 10 according to the present invention. The portable radiation cassette 10 includes the following: -Scintillator 20 capable of converting incident X-rays into optical signals, - A photosensitive slab 30 capable of converting the light signal emitted by the scintillator 20 into an electric charge. The photosensitive slab 30 is implicitly the matrix of a photosensitive element. The scintillator 20 and the photosensitive slab 30 form a panel 40 having a front surface 410 and a rear surface 420 opposite the front surface 410, which are intended to receive incident X-rays. - An electronic circuit board 50 that guarantees the conversion of electric charge into a digital image. - A mechanical protective enclosure 60 in which the panel 40 and the electronic circuit board 50 are arranged, the mechanical protective enclosure 60 including a top surface 610 and a bottom surface 620.

[0030] The top surface 610 of the mechanical protective housing 60 includes the following: - A first layer 611 of a rigid material consisting of aluminum and / or magnesium and / or carbon or mineral organic fiber composite; - A second layer 612 of rigid material. The second layer 612 of rigid material is in direct contact with the front surface 410 of the panel 40. Specifically, the scintillator 20 of the panel 40 leans against the second layer 612 of rigid material. Thus, the second layer 612 of rigid material ensures the role of a rigid structure and thus allows the panel 40, which is a fragile element, to be held firmly in place. Without this contact, simple twisting of the panel could lead to undesirable deterioration of the panel 40. Preferably, the second layer 612, which may be composed of a different material from the first layer 611, is obtained from the same rigid material as the first layer 611; - A layer 613 of cellular material is placed between the first rigid material layer 611 and the second rigid material layer 612. The layer 613 of cellular material can be made of cellular material.

[0031] This structure, in which a layer 613 of cellular material is stacked with a second layer 612 of rigid material, can be likened to a so-called "sandwich" structure. Thus, the layer 613 of cellular material contacts the first layer 611 and the second layer 612 of rigid material to completely fill the space within the mechanical protective housing 60 between them. This continuous stacking has the advantage of minimizing X-ray absorption while ensuring the overall rigidity of the assembly against both impact and torsion. As a variation, the layer 613 of cellular material can be fixed to the first layer 611 and the second layer 612 of rigid material. As an implied example, this fixing can be done by adhesive bonding.

[0032] Thanks to this new structure, the base that is formed inside the portable radiation cassette based on state-of-the-art technology can be eliminated, allowing the new portable radiation cassette to be lighter.

[0033] Advantageously, the first layer 611 and the second layer 612 of the rigid material, like the layer 613 of the cellular material, weakly absorb X-rays, thereby ensuring good X-ray reception for the scintillator 20 of the panel 40. Furthermore, the second layer 612 of the rigid material can be bonded to the front surface 410 of the panel 40 to completely fix the panel 40 to the second layer 612 and ensure good rigidity of the panel 40. Thus, any type of permanent adhesive that allows the panel 40 to be bonded to the second layer 612 of the rigid material, such as a double-sided adhesive, a quick-drying plastic adhesive, or any other weak chemical bond (called a van der Waals bond), can be used.

[0034] Furthermore, the portable radiation cassette 10 according to the present invention may include an anti-backscattering protective film 90 positioned against the rear surface 420 of the panel 40. Ideally, the anti-backscattering protective film 90 is in direct contact with the rear surface 420 of the panel 40. The anti-backscattering protective film 90 is preferably composed of one or at least one high atomic mass material or combination of materials whose atomic numbers are cleverly selected, and is intended to restrict the backscattering of X-rays toward the panel 40 to a direction substantially opposite to the incident direction Z of the X-rays, which could potentially impair the correct operation of the panel 40 and therefore the portable radiation cassette 10. The portable radiation cassette 10 may also include an electromagnetic shielding plate 92 positioned against the anti-backscattering protective film 90 on the other side of the anti-backscattering protective film 90 to insulate the panel 40 from any electromagnetic waves generated by the electronic circuit board 50.

[0035] The portable radiation cassette 10 may include an insulating layer 94, which is positioned between the electronic circuit board 50 and the rear surface 420 of the panel 40 to insulate the panel from the heat generated by the electronic circuit board 50.

[0036] Finally, the portable radiation cassette 10 may include an energy source (not shown) for the electronic circuit board 50.

[0037] Figure 3 shows an exploded view of the top surface 610 of the housing 60 of the portable digital cassette 10. As previously mentioned, the top surface 610 of the housing 60 of the portable digital cassette 10 is defined by a continuous stacking of a first layer 611, a layer of cellular material 613, and a second layer of rigid material 612.

[0038] Therefore, the first layer 611 is defined by a first thickness e1, the second layer 612 of rigid material is defined by a second thickness e2, and the layer 613 of cellular material is defined by a third thickness e3. According to one aspect of the present invention, the first thickness e1 and the second thickness e2 are the same. Therefore, and as an example, the first thickness e1 and the second thickness e2 can be a minimum thickness of about 0.2 mm to a maximum thickness of about 0.7 mm. Nevertheless, asymmetric structures can also be conceived. Therefore, the first thickness e1 of the first layer 611 may be different from the second thickness e2 of the second layer 612. As an example, the first thickness e1 may be 0.3 mm to 1.5 mm, and the second thickness e2 may be 0.3 mm to 1 mm. Preferably, in the case of an asymmetric structure of the first thickness e1 and the second thickness e2, the first thickness e1 is greater than the second thickness e2. In fact, with respect to the first layer 611 which can be compared to the outer sheath of the housing 60, increasing its thickness (i.e., increasing the thickness e1) makes it possible to increase the thickness of the outer sheath of the housing 60, and thus make it possible to increase the resistance of the housing 60 to shocks and deformations originating from the external environment.

[0039] The third thickness e3 of the cellular material layer 613 is considerably larger than the first thickness e1 and the second thickness e2. More specifically, the third thickness e3 can be, for example, 2 to 4 millimeters. Therefore, it is possible to establish a size ratio between the third thickness e3 and the sum of the first and second thicknesses e1 and e2, and this size ratio can vary between 2 and 8 depending on the sizes of the first, second, and third thicknesses e1, e2, and e3.

[0040] Therefore, in addition to the fact that the bubble material layer 613 is generally non-absorbent to X-rays, this small dimensionality of the first thickness e1 and the second thickness e2, which are much smaller than the third thickness of the bubble material layer, does not degrade the quality of the resulting image.

[0041] In practice, the layer 613 of the cellular material is composed of an organic composite that absorbs little or no X-rays. More specifically, in the first embodiment, the layer 613 of the cellular material includes a number of beads 6130. These semi-rigid beads 6130 completely fill the third thickness e3. Furthermore, with beads 6130 having a circular or elliptical shape and the layer 613 of the cellular material having a parallelepiped shape, the empty space 6140 between the beads 6130 appears uniform. Therefore, in the event of an impact or load that induces deformation of the layer 613 of the cellular material, the beads 6130 are compressed against each other, and thus reduce the empty space 6140. Furthermore, since the beads 6130 are semi-rigid, they can also be deformed in the event of an extreme impact or load applied to the layer 613 of the cellular material.

[0042] In this way, the layer 613 of the cellular material remains a rigid layer to undertake deformation associated with impact or load rather than the panel 40, and is not a malleable cellular material that retains its ability to be fully deformable.

[0043] In addition, to increase the ability of the deformable bead 6130, the bead 6130 may be a hollow bead.

[0044] Nevertheless, in the second embodiment, the layer 613 of the cellular material may include, instead of the bead 6130, a stack of at least partially hollow tubes 6150 extending substantially perpendicular to the front surface 411 of the panel 40, as shown in Figure 4. Like an internal bamboo structure, the tubes 6150 are partitioned by nodes so that they can be considered as a set of tubes separated by partitions. The tubes 6150 thus stacked within the layer 613 of the cellular material are in direct contact with each other.

[0045] The tubes 6150 may have an elliptical, square, or rectangular cross-section, but a hexagonal cross-section is preferred. The tubes extend approximately parallel to the X-ray incidence direction Z at a third thickness e3 of the layer 613 of the cellular material. Thus, there are also empty spaces 6140 between the tubes 6150 that allow the layer 613 of the cellular material to be easily deformed. Furthermore, the tubes 6150 may also be deformable, further increasing the ability of the layer 613 of the cellular material to be deformed in the event of an impact or load that induces deformation of the layer 613 of the cellular material.

[0046] Furthermore, in another preferred embodiment, it is conceivable to use a layer 613 of cellular material comprising a deformable material such as a series of cellular materials and rigid cellular bodies defined as macroscopically uniform cavities, the cellular bodies having a matrix macroscopic shape such as a honeycomb that exhibits macroscopic uniformity. Otherwise, the non-uniform presence of empty spaces within the layer 613 of cellular material may induce shading on the generated image and thus degrade the quality of the generated image.

[0047] Furthermore, it is also conceivable to use an expanded structure within the layer 613 of the cellular material to increase its ability to deform.

[0048] Therefore, the top surface 610 of the housing 60 of the portable digital cassette 10 (defined by a continuous stacking of a first layer 611, a layer of bubble material 613, and a second layer of rigid material 612) exhibits rigidity 3 to 10 times higher than the rigidity of the housing 6, in addition to the rigidity of the base formed inside the housing 6 by the state-of-the-art technology shown in Figure 1. Furthermore, the deformation of the top surface 610 of the housing 60 in the event of being dropped or bent is reduced by the same proportion. The panel 40 bonded to this top surface 610 via the second layer 612 is virtually immovable and no longer undergoes deformation that could damage the housing 60. Furthermore, this "sandwich" structure of the continuous stacking of the first layer 611, the bubble material layer 613, and the rigid material second layer 612 makes it possible to limit the thickness of the top surface 610 to a thickness equivalent to the thickness commonly used in the structure of portable radiation cassette 1, thus conforming to the ISO 4090 standard and without degrading the quality of the generated image, and the bubble material layer 613 exhibits negligible X-ray absorption. [Explanation of symbols]

[0049] 1 Portable Radiation Cassette 2 scintillators 3. Photosensitive slab 4 panels 5. Electronic circuit board 6 cabinets 7 Fixed support 8. Soft foam 10 Portable Radiation Cassettes 20 Scintillators 30 Photosensitive slab 40 panels 41 Front 42 Rear 43 Horizontal edge 50 Electronic circuit boards 60 Mechanical protective housing 61 Top surface 62 Bottom 63 Side view 64 Cavity 90 Anti-backscatter protective film 92 Electromagnetic Shielding Plate 94. Insulation layer 410 Front 420 Rear 610 Top 611 First layer 612 Second layer 613 Layer of bubble material 620 base 6130 Numerous beads 6140 Empty space 6150 tube e1, e2, e3 thickness

Claims

1. a scintillator (20) capable of converting incident X-rays into a light signal, a photosensitive slab (30) capable of converting the light signal emitted by the scintillator (20) into an electric charge, the scintillator (20) and the photosensitive slab (30) forming a panel (40), the panel (40) having a front surface (410) intended to receive the incident X-rays and a rear surface (420) opposite the front surface (410); an electronic circuit board (50) ensuring the conversion of said charges into a digital image; a portable radiation cassette (10) comprising a mechanical protective housing (60) in which the panel (40) and the electronic circuit board (50) are arranged and which comprises a top surface (610) and a bottom surface (620), the portable radiation cassette (10) being characterized in that the top surface (610) of the mechanical protective housing (60) - a first layer of rigid material (611), a second layer (612) of rigid material in contact with said front surface (410) of said panel (40); - a layer of foam material (613) disposed between said first layer of rigid material (611) and said second layer of rigid material (612) and in contact with said first layer of rigid material (611) and said second layer of rigid material (612).

2. 10. The portable radiological cassette (10) of claim 1, wherein said layer of foam material (613) is made of foam.

3. 2. The portable radiological cassette (10) of claim 1, wherein the layer (613) of foam material comprises a stack of at least partially hollow tubes (6150) extending substantially perpendicular to the front surface (410) of the panel (40).

4. 10. The portable radiological cassette (10) of claim 1, wherein the layer of foam material (613) comprises a number of beads (6130).

5. 5. The portable radiological cassette (10) of claim 4, wherein the bead (6130) is hollow.

6. A portable radiological cassette (10) according to any one of the preceding claims, wherein the second layer (612) of rigid material is adhered to the front surface (410) of the panel (40).

7. 7. A portable radiological cassette according to claim 1, wherein the layer of foam material (613) is defined by a third thickness (e3), and the first layer of rigid material (611) and the second layer of rigid material (612) are defined by first and second thicknesses (e1, e2), respectively, and the first and second thicknesses (e1, e2) are less than the third thickness (e3) of the layer of foam material (613).

8. A portable radiological cassette (10) according to any one of the preceding claims, wherein said layer of foam material (613) is made of an organic compound.

9. 9. A portable radiological cassette (10) according to any one of claims 1 to 8, wherein the first layer of rigid material (611) and / or the second layer of rigid material (612) are made of aluminium and / or magnesium and / or carbon or mineral organic fibre composite.

10. 10. The portable radiation cassette (10) according to any one of claims 1 to 9, comprising an anti-backscattering protective film (90) arranged against the rear face (420) of the panel (40) and preferably made of at least one material with a high atomic mass.

11. 11. The portable radiological cassette of claim 1, further comprising a thermal insulation layer (94) positioned between the electronic circuit board (50) and the rear face (420) of the panel (40).

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