Radiation detector structure

Abstract

The invention relates to a radiation detector structure. The invention relates to a portable radiation cassette (10) comprising: a scintillator (20); a photoplate (30), the scintillator and the photoplate forming a panel (40), the panel having a front face (410) intended to receive incident X-rays and a back face (420) opposite the front face; an electronic circuit board (50); a mechanical protection housing (60), the panel and the electronic circuit board being disposed in the mechanical protection housing, the mechanical protection housing comprising a top face (610) and a bottom face (620); characterized in that the top face of the mechanical protection housing comprises: a first layer of rigid material (611); a second layer of rigid material (612), the second layer of rigid material being in contact with the front face of the panel; a layer of porous material (613) disposed between the first layer of rigid material and the second layer of rigid material.

Description

Technical Field

[0001] This invention belongs to the field of imaging. It can be applied to any type of imager, especially X-ray imagers, visible light imagers, and infrared imagers. This invention is explained herein by way of example in the field of X-ray medical imaging and without loss of applicability to other imaging fields. This invention relates to a portable radiography cassette, and more particularly to an innovative radiography cassette structure that enhances protection of the cassette in the event of drops, impacts from external objects, localized or distributed pressure, and any stress. Background Technology

[0002] In the past, radiation systems were bulky and essentially immobile. It was necessary to position an object relative to the system to obtain the desired image. With the advent of solid-state detectors, detectors became less bulky and could be moved relative to a stationary object. For medical radiation, digital detectors are now manufactured in the form of mobile boxes, which can now be placed near the patient who needs the image even when the patient's health condition prevents him or her from moving to a room reserved for radiation.

[0003] A digital radiography cassette mainly consists of the following: at least one scintillator that emits visible light in the presence of X-rays; a matrix of photodiodes fabricated on a substrate typically made of glass (hereinafter referred to as a "slab") that converts the light signals emitted by the scintillator into electrical charges; and one or more electronic circuit boards that read these charges and convert them into visible digital images.

[0004] The need for flexibility and responsiveness when using this type of equipment has prompted manufacturers to develop portable forms of digital radiography cassettes. These portable cassettes must balance extreme resistance to external aggression with reduced weight and size. Indeed, when the weight of a patient is applied to a detector that is not uniformly supported, these portable cassettes are susceptible to drops, impacts from external objects, localized or distributed pressure loads, and bending stresses during handling and throughout their lifespan. Therefore, the mechanical structure of the detector needs to ensure maximum protection for vulnerable components, such as the scintillator, plate, and electronic circuit boards.

[0005] In the traditional design of portable X-ray cassettes, a scintillator is associated with a flat plate to form a subassembly called a panel. This panel rests against a base that provides it with rigidity and mechanical support. Finally, the panel is fitted with one or more electronic circuit boards before being inserted into the housing. To limit the overall weight of the portable cassette and ensure low absorption of X-rays passing through it, the thickness of the housing, and particularly the thickness of the front of the housing facing the X-ray source, is typically limited.

[0006] Figure 1 This is a cross-sectional view showing the structure of a portable radiation cassette known from the prior art. Typically, the portable radiation cassette 1 includes:

[0007] -Scintillator 2, which can convert incident X-rays into light signals.

[0008] - A photosensitive plate 3, which is capable of converting the light signal emitted by the scintillator 2 into electrical charge after X-ray conversion. The scintillator 2 and the photosensitive plate 3 then form a panel 4. The panel 4 includes a front surface 41 designed to receive incident X-rays according to the incident direction Z of the X-rays, a back surface 42 opposite to the front surface 41, and two sides 43 (in a cross-sectional view).

[0009] - Electronic circuit board 5, which ensures that electrical charge is converted into digital images.

[0010] - A mechanical protective housing 6, a panel 4, and an electronic circuit board 5 are disposed in the mechanical protective housing, which includes a top surface 61 for incident X-ray projection, a bottom surface 62 opposite to the top surface 61, and two side surfaces 63 (in a cross-sectional view).

[0011] The portable radiation cassette 1 also includes two fixed supports 7 located inside the housing 6, each fixed support 7 being disposed against the side 63 of the housing. The two fixed supports 7 form a base for the panel 4.

[0012] The panel is held against the side 63 of the housing 6 at its side 43 by a fixed support 7. Therefore, at least one cavity 64 exists inside the housing 6, defining an empty space between the front surface 41 of the panel 4 and the top surface 61 of the housing 6. Optionally, a second empty space may also exist between the back surface 42 of the panel 4 and the bottom 62 of the housing 6, which is partially filled by the electronic circuit board 5.

[0013] The flexible foam 8 is then inserted into the cavity 64 to completely fill it, making physical contact with the front face 41 of the panel 4 on one side and with the front face 61 of the housing 6 on the other side. ISO 4090 standards impose size restrictions on portable cases, therefore the flexible foam 8 must possess extremely high elasticity. This flexible foam 8 provides protection against impacts along the X-ray incident direction Z.

[0014] Therefore, the base formed by the fixed support 7 provides rigidity and prevents the panel 4 from deforming excessively in the event of the portable box being dropped or bent, and the flexible foam 8 of the housing 6 enables the panel 4 to be protected from impacts. Finally, the combined rigidity of the housing 6 (accompanied by the flexible foam 8) and the base prevents any significant degradation under pressure on the box.

[0015] However, the thickness limitations of the housing, and especially the adherence to the ISO 4090 standard which limits the size to 15 mm, prevent the provision of a thickness that is desirable for each of these parts (i.e., the base, housing 6, and flexible foam 8) to fully meet their functions.

[0016] Therefore, according to Figure 1 The portable box 1 described in the text is not proven to be as robust as expected. Summary of the Invention

[0017] The present invention aims to alleviate all or some of the problems mentioned above by proposing an innovative portable radiography cassette structure that can enhance its rigidity, ensure better resistance to deformation, and more effectively protect the fragile components contained in the portable radiography cassette.

[0018] Therefore, the subject of this invention is a portable radiation cassette, the portable radiation cassette comprising:

[0019] - A scintillator, which converts incident X-rays into optical signals.

[0020] - A photosensitive plate capable of converting the light signal emitted by the scintillator into electrical charge, the scintillator and the photosensitive plate forming a panel, the panel having a front side designed to receive the incident X-rays and a back side opposite to the front side.

[0021] - An electronic circuit board that ensures the conversion of the electrical charge into a digital image.

[0022] - A mechanical protective housing, in which the panel and the electronic circuit board are disposed, the mechanical protective housing including a top surface and a bottom surface;

[0023] The mechanical protective housing is characterized in that its top surface comprises:

[0024] -First rigid material layer,

[0025] - A second rigid material layer, the second rigid material layer being in contact with the front surface of the panel.

[0026] - A porous material layer, wherein the porous material layer is disposed between the first rigid material layer and the second rigid material layer.

[0027] According to one aspect of the invention, the porous material layer is made of a foamed material.

[0028] According to one aspect of the invention, the porous material layer comprises a plurality of at least partially hollow tubes that extend substantially at right angles to the front surface of the panel.

[0029] According to one aspect of the invention, the porous material layer comprises a plurality of beads.

[0030] According to one aspect of the invention, the bead is hollow.

[0031] According to one aspect of the invention, the second rigid material layer is bonded to the front side of the panel.

[0032] According to one aspect of the invention, the porous material layer is defined by a third thickness, and the first rigid material layer and the second rigid material layer are defined by a first thickness and a second thickness, respectively, wherein the first thickness and the second thickness are less than the third thickness of the porous material layer.

[0033] According to one aspect of the invention, the porous material layer is composed of an organic composite material.

[0034] According to one aspect of the invention, the first rigid material layer and / or the second rigid material layer are composed of aluminum and / or magnesium and / or carbon or mineral organic fiber composite materials.

[0035] According to one aspect of the invention, the portable radiation cassette includes an anti-backscattering protective layer disposed against the back side of the panel, the anti-backscattering protective layer preferably being composed of at least one high atomic mass material.

[0036] According to one aspect of the invention, the portable radiation cassette includes a heat insulation layer located between the electronic circuit board and the back side of the panel. Attached Figure Description

[0037] A better understanding of the invention and other advantages will become apparent after reading the detailed description of the embodiments given by way of example, illustrated in the accompanying drawings, in which:

[0038] Figure 1 A schematic cross-sectional view of a portable digital box structure known from the prior art;

[0039] Figure 2 The portable digital box structure according to the present invention is illustrated schematically.

[0040] Figure 3 An exploded view schematically showing the top surface of the housing of the portable digital box according to the present invention;

[0041] Figure 4An exploded view schematically showing the top surface of the housing of a portable digital box according to a variation of the present invention.

[0042] For clarity, the same elements will have the same reference numerals in different figures. Detailed Implementation

[0043] Figure 2 A portable digital cassette 10 according to the present invention is schematically shown. The portable radiation cassette 10 includes:

[0044] - Scintillator 20, which is capable of converting incident X-rays into optical signals.

[0045] - A photosensitive plate 30, which is capable of converting the light signal emitted by the scintillator 20 into electrical charge. As an indicative example, the photosensitive plate 30 is a matrix of photosensitive elements. The scintillator 20 and the photosensitive plate 30 form a panel 40, which has a front side 410 designed to receive incident X-rays and a back side 420 opposite to the front side 410.

[0046] - Electronic circuit board 50, which ensures that electrical charge is converted into a digital image.

[0047] - A mechanical protective housing 60, a panel 40, and an electronic circuit board 50 are disposed in the mechanical protective housing, which includes a top surface 610 and a bottom surface 620.

[0048] The top surface 610 of the mechanical protective housing 60 includes:

[0049] - First rigid material layer 611, which is composed of aluminum and / or magnesium and / or carbon or mineral organic fiber composite material;

[0050] - Second rigid material layer 612. The second rigid material layer 612 is in direct contact with the front surface 410 of the panel 40. More specifically, the scintillator 20 of the panel 40 abuts against the second rigid material layer 612. Therefore, the second rigid material layer 612 ensures the function of the rigid structure and thus allows the panel 40, as a fragile element, to be rigidly held. Without this contact, simple twisting of the panel would lead to the deterioration of the panel 40, which is undesirable. Preferably, the second layer 612 is obtained from the same rigid material as the first layer 611, but the second layer 612 may be made of a different material than the first layer 611;

[0051] - A porous material layer 613 is disposed between a first rigid material layer 611 and a second rigid material layer 612. The porous material layer 613 may be made of a foamed material.

[0052] This stacked structure of the first rigid material layer 611, the porous material layer 613, and the second rigid material layer 612 can be compared to a so-called "sandwich" structure. The porous material layer 613 thus contacts the first rigid material layer 611 and the second rigid material layer 612 to completely fill the space between the first rigid material layer 611 and the second rigid material layer 612 in the mechanical protective housing 60. This continuous stacking provides the advantage of ensuring the overall rigidity of the assembly, resistance to impact and torsion, while minimizing X-ray absorption. As a variation, the porous material layer 613 can be fixed to the first rigid material layer 611 and the second rigid material layer 612. As an indicative example, this fixing can be accomplished by gluing.

[0053] This new structure eliminates the need for a base formed in portable radiography cassettes according to existing technology, thus allowing the new portable radiography cassette to be lighter.

[0054] Advantageously, the first rigid material layer 611 and the second rigid material layer 612, like the porous material layer 613, weakly absorb X-rays, thereby ensuring good X-ray reception by the scintillator 20 of the panel 40. Furthermore, the second rigid material layer 612 can be glued to the front side 410 of the panel 40 to perfectly abut and fix the panel 40 to the second layer 612 and ensure good rigidity of the panel 40. Therefore, any type of permanent adhesive that allows the panel 40 to be glued to the second rigid material layer 612 can be used, such as double-sided adhesive, a dryable stretchable adhesive, or any other weak chemical bond (referred to as van der Waals bonding).

[0055] Furthermore, the portable radiography cassette 10 according to the invention may include an anti-backscattering protective layer 90 disposed against the back surface 420 of the panel 40. Ideally, the anti-backscattering protective layer 90 is in direct contact with the back surface 420 of the panel 40. The anti-backscattering protective layer 90 is preferably composed of one or at least one high atomic mass material or a combination of materials whose atomic number is precisely selected and designed to limit the backscattering of X-rays toward the panel 40 in a direction substantially opposite to the incident direction Z of the X-rays, which could potentially impair the proper operation of the panel 40 and thus damage the portable radiography cassette 10. The portable radiography cassette 10 may also include an electromagnetic shielding plate 92 disposed on the other side of the anti-backscattering protective layer 90 and against the anti-backscattering protective layer 90 to isolate the panel 40 from any electromagnetic waves generated by the electronic circuit board 50.

[0056] The portable radiation cassette 10 may include a heat insulation layer 94 located between the electronic circuit board 50 and the back surface 420 of the panel 40 to insulate the panel from the heat generated by the electronic circuit board 50.

[0057] Finally, the portable radiation cassette 10 may include a power source (not shown) for the electronic circuit board 50.

[0058] Figure 3 An exploded view of the top surface 610 of the housing 60 of the portable digital box 10. As previously described, the top surface 610 of the housing 60 of the portable digital box 10 is defined by a first layer 611, a porous material layer 613, and a second rigid material layer 612 that are stacked sequentially.

[0059] Therefore, the first layer 611 is defined by a first thickness e1, the second rigid material layer 612 by a second thickness e2, and the porous material layer 613 by a third thickness e3. According to one aspect of the invention, the first thickness e1 and the second thickness e2 are the same. Thus, by way of example, the first thickness e1 and the second thickness e2 can be between a minimum thickness of approximately 0.2 mm and a maximum thickness of approximately 0.7 mm. However, an asymmetrical structure is also conceivable. Therefore, the first thickness e1 of the first layer 611 can be different from the second thickness e2 of the second layer 612. As an example, the first thickness e1 can be between 0.3 mm and 1.5 mm, while the second thickness e2 can be between 0.3 mm and 1 mm. Preferably, in the case of an asymmetrical structure between the first thickness e1 and the second thickness e2, the first thickness e1 is greater than the second thickness e2. In fact, increasing the thickness of the first layer 611, which can be likened to the outer skin of the shell 60 (i.e., increasing the thickness e1), allows for an increase in the thickness of the outer skin of the shell 60, and thus increases the resistance of the shell 60 to impacts and deformations originating from the external environment.

[0060] The third thickness e3 of the porous material layer 613 is much greater than the first thickness e1 and the second thickness e2. More specifically, the third thickness e3 can be, for example, between 2 mm and 4 mm. Therefore, a size ratio can be established between the third thickness e3 and the sum of the first thickness e1 and the second thickness e2, and this size ratio can vary between 2 and 8, depending on the dimensions of the first thickness e1, the second thickness e2, and the third thickness e3.

[0061] Therefore, the small size of the first thickness e1 and the second thickness e2, which are much smaller than the third thickness of the porous material layer, coupled with the fact that the porous material layer 613 is largely non-absorbent relative to X-rays, does not degrade the quality of the generated image.

[0062] In fact, the porous material layer 613 is composed of an organic composite material that absorbs little or no X-rays. More specifically, in the first embodiment, the porous material layer 613 includes a plurality of beads 6130. These semi-rigid beads 6130 completely fill the third thickness e3. Furthermore, when the beads 6130 have a circular or elliptical shape and the porous material layer 613 has a parallelepiped shape, the empty spaces 6140 between the beads 6130 are uniformly distributed. Therefore, in the event of an impact or load that causes deformation of the porous material layer 613, the beads 6130 press against each other, thereby reducing the empty spaces 6140. Moreover, since the beads 6130 are semi-rigid, they can also deform under extreme impacts or loads applied to the porous material layer 613.

[0063] In this way, the porous material layer 613 remains a rigid layer instead of retaining fully deformable stretchable foam, so as to withstand the deformation associated with impact or load instead of the panel 40.

[0064] Furthermore, in order to increase the deformability of bead 6130, bead 6130 can be a hollow bead.

[0065] However, in the second embodiment, instead of beads 6130, the porous material layer 613 may include a plurality of at least partially hollow tubes 6150, which extend substantially at right angles to the front surface 410 of the panel 40, such as... Figure 4 As shown. Similar to the internal bamboo-like structure, the tubes 6150 are separated by nodes, so they can be considered as a group of tubes separated by membranes. Thus, the tubes 6150 stacked in the porous material layer 613 are in direct contact with each other.

[0066] The tube 6150 can have an elliptical, square, or rectangular cross-section, but is preferably hexagonal. The tube extends substantially parallel to the incident direction Z of the X-rays within the third thickness e3 of the porous material layer 613. Therefore, empty spaces 6140 also exist between the tubes 6150, allowing the porous material layer 613 to be easily deformable. Furthermore, the tubes 6150 can also be deformable, thereby further increasing the ability of the porous material layer 613 to deform under impact or load that would cause deformation of the porous material layer 613.

[0067] Furthermore, in another preferred embodiment, it is conceivable to use a porous material layer 613 comprising a rigid foam defined as a series of deformable materials (such as porous materials) and having macroscopically uniform cavities. This foam has a macroscopic matrix form (such as a honeycomb structure) and thus exhibits macroscopic uniformity. Otherwise, the presence of non-uniformity in the hollow spaces within the porous material layer 613 would cause shadows on the resulting image and thus degrade the quality of the resulting image.

[0068] In addition, it is conceivable to use an expansion structure within the porous material layer 613 to increase its deformability.

[0069] Therefore, the top surface 610 of the housing 60 of the portable digital box 10 (defined by a continuously stacked first layer 611, a porous material layer 613, and a second rigid material layer 612) provides a better surface than according to... Figure 1 The rigidity of the prior art housing 6, plus the rigidity of the base formed inside the housing 6, is three to ten times greater. Furthermore, the deformation of the top surface 610 of the housing 60 is reduced proportionally in the event of a drop or bending. The panel 40, bonded to the top surface 610 via the second layer 612, is virtually undeformable and therefore no longer subject to deformation that could damage it. Moreover, this "sandwich" structure of the continuous stacking of the first layer 611, the porous material layer 613, and the second rigid material layer 612 allows the thickness of the top surface 610 to be limited to a thickness typically used in constructing portable radiographic cassettes 1, thus conforming to ISO 4090 standards, without degrading the quality of the resulting images; the porous material layer 613 exhibits negligible X-ray absorption.

Claims

1. A portable radiation cassette (10), the portable radiation cassette (10) comprising: - A scintillator (20) capable of converting incident X-rays into optical signals. - A photosensitive plate (30) capable of converting the light signal emitted by the scintillator (20) into an electrical charge, the scintillator (20) and the photosensitive plate (30) forming a panel (40) having a front side (410) intended to receive the incident X-rays and a back side (420) opposite to the front side (410). - Electronic circuit board (50), which ensures that the charge is converted into a digital image. - A mechanical protective housing (60), in which the panel (40) and the electronic circuit board (50) are disposed, the mechanical protective housing including a top surface (610) and a bottom surface (620). The mechanical protective housing (60) is characterized in that its top surface (610) comprises: - First rigid material layer (611). - A second rigid material layer (612) is in contact with the front surface (410) of the panel (40). - A porous material layer (613) is disposed between the first rigid material layer (611) and the second rigid material layer (612), the porous material layer (613) being in contact with the first rigid material layer (611) and the second rigid material layer (612).

2. The portable radiation cassette (10) according to claim 1, wherein, The porous material layer (613) is made of foamed material.

3. The portable radiation cassette (10) according to claim 1, wherein, The porous material layer (613) includes a plurality of at least partially hollow tubes (6150) that extend substantially at right angles to the front side (410) of the panel (40).

4. The portable radiation cassette (10) according to claim 1, wherein, The porous material layer (613) includes a plurality of beads (6130).

5. The portable radiation cassette (10) according to claim 4, wherein, The bead (6130) is hollow.

6. The portable radiation cassette (10) according to any one of claims 1 to 5, wherein, The second rigid material layer (612) is glued to the front side (410) of the panel (40).

7. The portable radiation cassette (10) according to claim 1, wherein, The porous material layer (613) is defined by a third thickness (e3), and the first rigid material layer (611) and the second rigid material layer (612) are defined by a first thickness (e1) and a second thickness (e2), respectively, wherein the first thickness (e1) and the second thickness (e2) are less than the third thickness (e3) of the porous material layer (613).

8. The portable radiation cassette (10) according to claim 1, wherein, The porous material layer (613) is composed of organic composite materials.

9. The portable radiation cassette (10) according to claim 1, wherein, The first rigid material layer (611) and / or the second rigid material layer (612) are composed of aluminum and / or magnesium and / or carbon or mineral organic fiber composite materials.

10. The portable radiography cassette (10) according to claim 1, wherein the portable radiography cassette (10) includes an anti-backscattering protective layer (90) disposed against the back surface (420) of the panel (40).

11. The portable radiation cassette (10) according to claim 1, wherein the portable radiation cassette (10) includes a heat insulation layer (94) located between the electronic circuit board (50) and the back surface (420) of the panel (40).

12. The portable radiation cassette (10) according to claim 10, wherein the anti-backscattering protective layer (90) is composed of at least one high atomic mass material.

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