CN106154302B - Scintillator plate for radiation detection flat panel detector and preparation method thereof - Google Patents

Abstract

The invention relates to a scintillator plate for a radiation detection flat panel detector and a preparation method thereof. The scintillator plate includes a substrate, a scintillator layer, and a reflective layer sandwiched between the substrate and the scintillator layer, wherein the scintillator The chemical formula of the body layer is (Lu _(1‑x‑y) C _x A _y ) ₃ Al ₅ O ₁₂ , and the ions available for the A site include Ca ²⁺ , Mg ²⁺ , Sr ²⁺ , Ba ²⁺ , Li ⁺ , Na ⁺ , K ⁺ at least one, 0.001≤x≤0.05, 0.0005≤y≤0.05. The (Lu,A) ₃ Al ₅ O ₁₂ : Ce transparent ceramic ray flat panel detector of the present invention has the characteristics of sharp imaging and high spatial resolution, and has the advantages of low maintenance cost, long service life and maintenance cost, and is applied to medical diagnosis , non-destructive testing, public safety, radiation dose testing and oil exploration and other devices that use ray testing.

Description

Scintillator plate for radiation detection flat panel detector and preparation method thereof

technical field

The invention belongs to the field of ray scintillator detector imaging devices, and in particular relates to a scintillator plate in a flat panel detector for ray detection and a preparation method thereof. The detector uses a scintillator plate to convert rays (or particles) such as γ-rays, β-rays or X-rays into visible light, and the visible light excites the photoelectric conversion device to generate current, which is then imported into the computer and converted into graphic information to realize the spatial distribution of rays. Digital photography. The detector using the scintillator plate can be applied to devices using radiation detection such as medical diagnosis, non-destructive detection, public safety, radiation dose detection and oil exploration.

Background technique

Radiation detection and imaging technology is widely used in many fields of production and life, such as medical imaging, industrial non-destructive testing, and airport station security inspection. The core component in ray detection is the detector. In recent years, with the continuous development of medical imaging technology, there is a demand for high-resolution fast real-time imaging of detectors. Digital Radiography (DR) based on flat panel detectors has become a new generation of real-time ray imaging technology due to its advantages of lightness, durability, high sensitivity, and small image distortion.

At present, radiation detection flat panel detectors are divided into direct energy conversion and indirect energy conversion. The indirect conversion type flat panel detector based on scintillator detector imaging is the most commonly used radiation imaging technology.

In such flat panel detector arrangements, scintillator detectors are used for imaging in order to convert the radiation into visible light. The scintillator used in commercial flat panel detectors is mainly CsI. Due to the special physical and chemical properties of CsI, such as low melting point and easy deliquescence, the current commercial scintillator flat panel detectors mostly use the epitaxial method to grow CsI columnar fiber films. Although the CsI thin film grown by this method can effectively improve the light collection efficiency, the transmittance of the CsI thin film prepared by this method is low, the preparation process is complicated, and the cost is high. In addition, due to the unstable chemical properties of CsI, there are point defects such as vacancies or vacancy groups in the CsI film grown by epitaxial method, which affects the luminous efficiency of the material.

The oxide scintillator of cubic garnet structure (Lu,Ce) ₃ Al ₅ O ₁₂ (LuAG:Ce) has the advantages of high density (ρ=6.73g/cm ³ ) and large effective atomic number (Z _eff ＝62.9) , has a strong ability to absorb radiation, and is an ideal radiation detection material. Using transparent ceramic preparation technology, ceramic scintillators with high optical quality and excellent luminescent performance can be prepared. At present, the alkaline earth metal Me ²⁺ co-doped (Lu,Ce,Me) ₃ Al ₅ O ₁₂ (LuAG:Ce,Me) scintillation ceramics prepared by us has a light yield higher than 22,000ph/MeV at a gate width of 1μs, and the attenuation With fast time (~40ns) and low afterglow, it is a very potential scintillator. At the same time, we design and process the microstructure of the transparent ceramic surface to prepare scintillator plates etched on the surface to improve light collection efficiency and improve the imaging resolution of scintillators.

Using (Lu,A) ₃ Al ₅ O ₁₂ :Ce ceramics with high optical quality, excellent luminescence performance and stable chemical properties as the scintillator provides the possibility to realize high-sharp imaging, clear and fast response ray detection flat panel detection. Chinese patents CN102934172A, CN 102820071A, CN 103563006A and CN 103675885A have reported device patents for radiation detection panels, in which the scintillators are commercial rare earth halides. Chinese patents CN 1034101C, CN1995274A, and CN 103380194A all report patents on garnet ceramics or single crystal scintillators, but their shortcomings lie in the scintillation performance of the material and the matching of back-end related electronics. Pomegranate has not been used before. A precedent for the preparation of flat-panel detectors for radiation detection by stone-ceramic scintillators. In addition, previous reports on flat-panel detectors, such as CN103675885A and CN102820071A, used a large number of epitaxial growth of columnar fibers to prepare scintillator layers, and there was no report on improving the detection performance of detectors by etching array units on scintillator plates.

Contents of the invention

The present invention aims to improve the existing radiation detection flat panel detector, and the invention provides a scintillator plate for radiation detection flat panel detector and a preparation method thereof.

The present invention provides a scintillator plate for a radiation detection flat panel detector. The scintillator plate includes a substrate, a scintillator layer, and a reflective layer sandwiched between the substrate and the scintillator layer, wherein the scintillator layer The composition chemical formula is (Lu _(1-xy) C _x A _y ) ₃ Al ₅ O ₁₂ , the optional ions for the A site include Ca ²⁺ , Mg ²⁺ , Sr ²⁺ , Ba ²⁺ , Li ⁺ , Na At least one of ⁺ and K ⁺ can be one kind of ion or a mixture of several kinds of ions, 0.001≤x≤0.05, 0.0005≤y≤0.05.

Preferably, the A site ion is Mg ²⁺ ; 0.001≤x≤0.01, more preferably 0.002≤x≤0.005; 0.0005≤y≤0.01, more preferably 0.001≤y≤0.005.

Preferably, the material of the substrate includes graphite, resin, glass or metal, the material of the reflective layer includes silica gel or epoxy resin, and the reflective layer has the functions of increasing the light emission of the scintillator plate and fixing the substrate and the scintillator layer.

Preferably, the reflective layer material contains 40-95wt% of light-scattering SiO ₂ particles.

Preferably, the thickness of the substrate is 0.05 mm to 10 mm, the thickness of the reflection layer is 0.01 μm to 0.5 μm, and the thickness of the scintillator layer is 50 μm to 500 μm.

Preferably, the thickness of the substrate is 0.05mm-4mm, more preferably 0.5mm-4mm, the thickness of the reflection layer is 0.01μm-0.2μm, and the thickness of the scintillator layer is 50μm-200μm.

Preferably, the surface of the scintillator layer has independent array units formed by etching, the array units are preferably rectangular, the side length of the rectangular array is 50 μm-200 μm, the pitch range is 10-20 μm, and the etching depth is 10-50 μm.

In addition, the present invention also provides a method for preparing the above-mentioned scintillator plate, comprising:

1) According to the chemical formula of the scintillator layer, a solid-phase reaction method or a liquid-phase method combined with ceramic sintering technology is used to prepare the scintillator layer material;

2) cutting the scintillator layer material prepared in step 1) into scintillator layer sheets of specified size;

3) After the scintillator layer sheet and the substrate are fixed through the reflective layer material, they are ground to a specified thickness and polished.

Preferably, before the scintillator layer sheet is polished, the cross section is rectangular, the side length ranges from 10 to 50 mm, and the thickness ranges from 1 mm to 4 mm;

Before the substrate is polished, the cross section is rectangular, the side length ranges from 20 to 70mm, and the thickness ranges from 1mm to 8mm.

Preferably, the preparation method also includes:

4) Etching the surface of the scintillator layer to form an array unit, wherein the etching method includes: wire cutting, laser cutting or inductively coupled plasma.

In addition, the present invention also provides a flat-panel detector containing the above-mentioned scintillator plate, and the flat-panel detector includes a scintillator plate, a light cone and a photoelectric conversion device.

In addition, the present invention also provides a transparent ceramic used in the above-mentioned scintillator plate, the composition chemical formula of the transparent ceramic is (Lu ( _{1 -xy) CexAy ) 3Al 5 O 12} , and the A site can be selected The ions include at least one of Ca ²⁺ , Mg ²⁺ , Sr ²⁺ , Ba ²⁺ , Li ⁺ , Na ⁺ , K ⁺ , which can be one kind of ion or a mixture of several ions, 0.001≤x ≤0.01, 0.0005≤y≤0.01.

The present invention also provides a method for preparing the above-mentioned transparent ceramics, comprising:

1) Prepare uniformly mixed raw material powders comprising lutetium oxide, aluminum oxide, cerium oxide, and co-doped ion oxides;

2) forming the raw material powder to obtain a ceramic green body;

3) Vacuum sintering the ceramic green body at 1700-1900° C. to obtain the transparent ceramic.

Preferably, the molding adopts dry pressing or cold isostatic pressing, wherein, dry pressing is dry pressing at 50-150 MPa for 1 to 5 minutes, and cold isostatic pressing is cold isostatic pressing at 200-400 MPa for 1-5 minutes. 10 minutes.

Preferably, the vacuum sintering is carried out at 1700-1820° C. for more than 10 hours under a vacuum degree of pressure ≤ 10 ⁻² Pa.

Beneficial effects of the present invention:

The (Lu,A) ₃ Al ₅ O ₁₂ : Ce transparent ceramic ray flat panel detector of the present invention has the characteristics of sharp imaging and high spatial resolution, and has the advantages of low maintenance cost, long service life and maintenance cost, and is applied to medical diagnosis , non-destructive testing, public safety, radiation dose testing and oil exploration and other devices that use ray testing. Designing the material microstructure by surface etching can effectively improve the imaging resolution of the system, and is applicable to all bulk scintillator materials.

Description of drawings

Fig. 1 shows a schematic diagram of the imaging principle of a flat panel detector prepared by a scintillator plate in an embodiment of the present invention;

2 shows a schematic structural view of a scintillator plate prepared by using (Lu,A) ₃ Al ₅ O ₁₂ :Ce transparent ceramics in one embodiment of the present invention;

Figure 3 shows the X-ray-excited luminescence spectrum of (Lu,A) ₃ Al ₅ O ₁₂ :Ce transparent ceramic scintillator prepared in one embodiment of the present invention, and a BGO single crystal of the same size grown by the pulling method as a reference Luminescence spectrum excited by X-rays of the sample;

Fig. 4 shows an optical microscope photo of (Lu,A) ₃ Al ₅ O ₁₂ :Ce transparent ceramic scintillator after surface etching prepared in one embodiment of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the drawings and the following embodiments. It should be understood that the drawings and the following embodiments are only used to illustrate the present invention rather than limit the present invention.

The object of the present invention is to provide a method for preparing an indirect conversion type radiation detection flat panel detector. Taking advantage of LuAG:Ce-based multi-component garnet (Lu,A) ₃ Al ₅ O ₁₂ :Ce transparent ceramics with high optical quality, excellent luminescence, excellent chemical properties and stable chemical properties to prepare a radiation detection flat panel detector with high spatial resolution . In addition, the microstructure of the material is designed by means of surface etching, thereby effectively improving the resolution of the flat panel detector.

In order to achieve the above object, the technical solution adopted by the present invention is: a high spatial resolution radiation detection flat panel detector. The radiation detection flat panel detector includes a scintillator plate, a light cone, a photoelectric conversion device and a computer data acquisition system.

In the present invention, the device used for radiation imaging is called a radiation detection flat panel detector. It is characterized by an indirect conversion radiation detection flat panel detector. The rays include γ-rays, β-rays or X-rays.

In the present invention, the part that absorbs rays and converts them into visible light is called a scintillator plate. It is characterized in that it consists of a scintillator layer, a reflective layer and a substrate.

In the present invention, the core component of the scintillator plate is the scintillator layer. It is characterized in that the material used can be a bulk scintillation material such as single crystal, ceramic or organic polymer compound. The selection of materials is mainly considered from the aspects of steady-state luminous efficiency, transmittance and processing performance of materials. Scintillator layer thickness range: 50 μm to 500 μm. In order to improve the visible light conversion efficiency of the scintillator layer, the surface needs to be etched.

In a preferred embodiment of the present invention, the thickness of the scintillator layer ranges from 50 μm to 200 μm.

In the present invention, the performance of the detector is optimized by etching the array unit on the surface of the scintillator layer. The surface etching process may be wire cutting, laser cutting, and inductively coupled plasma (ICP) etching, etc., but is not limited to the above methods. This process is suitable for microstructure design of single crystal, ceramic or organic polymer compound bulk scintillator materials.

In the present invention, after adopting the surface etching process, the surface of the scintillator is finally divided into multiple independent array units. Etched into an array unit, because this structure can generate light-conducting transmission on the surface of the scintillator and reduce total reflection loss, thereby improving the visible light collection efficiency of the device and increasing the spatial resolution of the system.

In the present invention, each independent array unit can be designed in different shapes according to actual needs.

In a preferred embodiment of the present invention, the etching surface is a rectangular array. The side length of the array ranges from 50 μm to 200 μm, and the pitch ranges from 10 μm to 20 μm.

In a preferred embodiment of the present invention, the material of the scintillator layer is a multi-component garnet (Lu,A) ₃ Al ₅ O ₁₂ :Ce transparent ceramic, and its chemical composition is (Lu _{(1-xy) Cex} A _y ) ₃ Al ₅ O ₁₂ , where A is a co-doped ion that can replace the Lu ³⁺ site. The available ions include Ca ²⁺ , Mg ²⁺ , Li ⁺ , etc. The basis for selecting co-doped ions It is possible to obtain a certain amount of Ce ⁴⁺ in the material through charge compensation, which can be a kind of co-doped ion or multiple co-doped ions; the value range of x is 0.001≤x≤0.05, and the value of y The range is 0.0005≤y≤0.05, preferably 0.0005≤y≤0.01, more preferably 0.001≤y≤0.005.

In a preferred embodiment of the present invention, the substituting ion A of the (Lu,A) ₃ Al ₅ O ₁₂ :Ce transparent ceramic is Mg ²⁺ .

In a preferred embodiment of the present invention, the value range of x of the (Lu,A) ₃ Al ₅ O ₁₂ :Ce transparent ceramic is: 0.001≤x≤0.01, more preferably 0.002≤x≤0.005.

In the present invention, the part that supports the scintillator layer and the normal operation of the scintillator layer is called a substrate. Substrate thickness range: 0.05mm ~ 10mm.

In the present invention, the substrate material may be materials with stable structural and chemical properties such as graphite, resin, glass and metal.

In a preferred embodiment of the present invention, the substrate material is graphite. Graphite is used as the substrate material, which has low density and less radiation absorption. In addition, it also has the advantages of excellent processability, easy bonding and low cost.

In a preferred embodiment of the present invention, the thickness of the substrate ranges from 0.05 mm to 4 mm.

In the present invention, the component between the scintillator layer and the substrate to increase the luminous intensity of the scintillator detector and reduce the scattering loss of visible light is called a reflective layer. The reflective layer has the functions of increasing the light emission of the scintillator plate and fixing the substrate and the scintillator layer. The substrate and the scintillator layer in the scintillator plate are fixed through the transparent adhesive in the reflective layer. After being emitted from the high-energy rays, they pass through the substrate and the reflective layer in the scintillator plate, and reach the scintillator layer to absorb and convert into visible light.

In the present invention, the reflective layer is composed of light scattering particles dispersed in a transparent adhesive. Reflective layer thickness range: 0.01μm～0.5μm. The transparent adhesive can be silicone or epoxy.

In a preferred embodiment of the present invention, the transparent adhesive selected for the reflective layer is silica gel. Using silica gel as a transparent adhesive has the advantages of high adsorption performance, good thermal stability, stable chemical properties, and high mechanical strength.

In a preferred embodiment of the present invention, the light scattering particles selected for the reflective layer are SiO ₂ particles. Because of its high refractive index, the reflectivity of the reflective layer can be increased, the luminescence loss of the scintillator layer can be reduced, and the imaging resolution can be improved.

In a preferred embodiment of the present invention, the thickness of the reflective layer ranges from 0.01 μm to 0.2 μm.

In the present invention, the scintillator plate is obtained by fixing the scintillator layer, the reflective layer and the substrate.

In the present invention, there are two design modes for collecting the visible light emitted by the scintillator and leading it into the photoelectric conversion device. First, adopt the traditional optical lens combination design mode, and complete the light introduction by designing the optical path. In order to improve the anti-irradiation performance of the optical path, this mode makes the system complex in structure, low in light transmission efficiency, and poor in system imaging resolution. Second, directly using the light cone as the transmission medium can avoid the above problems and effectively improve the imaging resolution of the system.

In a preferred embodiment of the present invention, the light cone used in the flat panel detector. Because of its high light collection efficiency, good coupling with the back-end photoelectric converter, and high imaging resolution.

In the present invention, a device that converts visible light into an electrical signal is called a photoelectric conversion device.

In the present invention, the photoelectric conversion device can be a photodiode, charge coupled device (CCD), complementary metal oxide semiconductor (CMOS) or photomultiplier tube (PMT), etc., but is not limited to the above devices.

In a preferred embodiment of the present invention, the photoelectric conversion device used in the flat panel detector is a CCD.

Utilizing the characteristics of good optical quality and high luminous efficiency of (Lu,A) ₃ Al ₅ O ₁₂ :Ce transparent ceramics, the flat panel detector has high imaging quality under X-ray excitation, and the pictures are clear and sharp. The MTF at 10lp/mm is above 17.5% by the lead wire-to-card method. When the knife-edge method is used to test the RQA5 experimental conditions stipulated in the standard IEC62220-1, when the MTF is 10%, the resolution is above 9lp/mm. Garnet transparent ceramics have good chemical stability, which can effectively increase the service life of the detector and reduce device packaging and maintenance costs. The high thermal conductivity and heat dissipation capacity of ceramics can be easily applied to different environments, especially those that require high temperature operation, such as oil well exploration.

The present invention provides a flat-panel detector for radiation detection, the structure schematic diagram and the principle of spatial resolution test are shown in FIG. 1 . Referring to FIG. 1 , the flat panel detector includes a scintillator plate, a light cone, a CCD, and a subsequent data acquisition card computer. Fig. 1 schematically shows that after the rays are emitted by the light source, they are converted into visible light by the (Lu,A) ₃ Al ₅ O ₁₂ :Ce transparent ceramic scintillator plate. Visible light is coupled into the CCD through the light cone and converted into electrical signals, and the analog imaging photos are collected by the computer.

In the present invention, the flat panel detector X-ray is used for imaging system testing. Knife-edge method test selects the RQA5 experimental conditions stipulated in the standard IEC62220-1 to conduct the test. When the MTF is 10%, the resolution is above 9lp/mm.

To sum up, the present invention uses scintillator as the radiation absorption and conversion medium, and provides a method for preparing an indirect conversion type radiation detection flat panel detector. Under ray excitation, the (Lu,A) ₃ Al ₅ O ₁₂ :Ce transparent ceramic scintillator emits visible light with a central wavelength of 510nm. This visible light is detected by the subsequent photoelectric converter and then imaged by computer simulation. Due to the high luminous intensity and low afterglow of the ceramic scintillator used in the scintillator flat panel detector, the system imaging is sharp and the spatial resolution is high. In addition, due to the excellent mechanical properties of ceramics, it has the advantages of good machinability, and it is easy to etch the surface. After the ceramic is etched, waveguide transmission occurs on the surface of the ceramic, reducing total reflection loss, thereby improving the visible light collection efficiency of the device and increasing the spatial resolution of the system. Therefore, the present invention can effectively solve the problems encountered in the development of current flat panel detectors, such as high maintenance cost and complex preparation process due to unstable chemical properties of the current commercial non-oxide scintillators. (Lu,A) ₃ Al ₅ O ₁₂ :Ce transparent ceramics with independent intellectual property rights, excellent optical quality (in-line transmittance >73% at 800nm of 2mm thick ceramics) and high luminous intensity (more than 7.5 times BGO) are used as the scintillator body, a flat panel detector with high spatial resolution (>9lp/mm) was prepared. At the same time, the flat panel detector has the advantages of simple maintenance and good thermal stability.

On the other hand, the present invention also provides a method for preparing the transparent ceramic scintillator plate, comprising: preparing a transparent ceramic scintillator by using a solid-phase reaction method or a liquid-phase method combined with ceramic sintering technology according to the chemical composition of the transparent ceramic scintillator; The prepared transparent ceramic block is processed and cut into a scintillator of a certain size; the transparent ceramic scintillator and the substrate material are fixed through a reflective layer; the multilayer composite structure is polished to a certain thickness; and the composite structure is The scintillator layer is cut into rectangular arrays.

The preparation method of the transparent ceramic used in the scintillator layer includes:

(1) Preparation of raw material mixed powder;

In one example, according to the chemical composition (Lu _(1-xy) C _x A _y ) ₃ Al ₅ O ₁₂ (where 0.001≤x≤0.01, 0.0005≤y≤0.01) of the transparent ceramic scintillator is prepared by solid state reaction method Raw material mixed powder. Specifically, lutetium oxide (Lu ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), cerium oxide (CeO ₂ ) and co-doped ion oxidation were used as raw materials, and 60 g of the two powder materials were accurately weighed, and anhydrous Ethanol or deionized water is used as the dispersion medium to carry out wet ball milling to mix evenly, the ball milling speed can be 80-200rmp/min, and the ball milling time can be 5-12 hours; then the mixed powder is dried and sieved to obtain the oxide Mix powder.

In another example, a liquid phase method can be used to prepare raw material mixed powder. Specifically, a precursor solution containing Lu ³⁺ , Al ^{3 +} , Ce ³⁺ and co-doped ions is selected, according to (Lu _(1-xy) C _x A _y ) ₃ Al ₅ O ₁₂ (where 0.001≤x≤0.01 , 0.0005≤y≤0.01) Mix the precursor solution and drop it into a precipitant such as NH ₄ HCO ₃ or NH ₃ ·H ₂ O. In order to improve the dispersibility of the powder, a certain amount of dispersant can also be added and surfactant, aging and washing, and calcining the obtained precipitates at 950-1200° C. for 4-8 hours to obtain (Lu,A) ₃ Al ₅ O ₁₂ :Ce powder. Wherein the precursor solution may be a soluble salt respectively containing Lu ³⁺ , Al ³⁺ , Ce ³⁺ and co-doped ions, such as hydrochloride, nitrate, acetate, sulfate and the like.

(2) Forming of raw material mixed powder. The mixed oxide powder obtained in (1) and the (Lu,A) ₃ Al ₅ O ₁₂ :Ce powder were first dry pressed and then cold isostatic pressed to increase the density of the green body. The dry pressing may be performed under 50-150 MPa for 1-5 minutes, and the cold isostatic pressing may be performed under 200-400 MPa for 1-10 minutes.

(3) Vacuum sintering. Vacuum sintering is carried out by keeping the green bodies obtained in (2) at 1700-1900°C (preferably 1700-1820°C) for 10 hours or more at a vacuum degree of 10 ^-2 Pa to 10 ^-4 Pa. The prepared ceramic samples were respectively polished to obtain (Lu,A) ₃ Al ₅ O ₁₂ :Ce transparent ceramics with high optical quality. The (Lu,A) ₃ Al ₅ O ₁₂ :Ce transparent ceramic scintillator can be obtained by polishing the sintered ceramic.

(4) Preparation of transparent ceramic scintillator plate. The transparent ceramic and the substrate are fixed as shown in FIG. 2 through the transparent adhesive in the reflective layer. The bonding position of the adhesive is not limited, as long as the composite structures can be fixed to each other and the scintillator can be guaranteed to emit light. The adhesive is filled with light-scattering particles to enhance reflection. The composite structure is ground and polished, and the surface of the (Lu,A) ₃ Al ₅ O ₁₂ :Ce transparent ceramic scintillator layer is etched to obtain a scintillator plate. After etching, the transparent ceramic surface is finally separated into multiple independent scintillator array units. Each independent array unit can be designed into different shapes according to actual needs. It should be understood that this etching process is also suitable for microstructure design of other bulk scintillator materials.

In a preferred embodiment of the present invention, the (Lu,A) ₃ Al ₅ O ₁₂ :Ce ceramic sheet used in the transparent ceramic scintillator layer has very excellent optical quality, and the in-line transmittance at 800nm for a 2mm thick sample More than 73%.

Under the excitation of X-rays emitted by the X-ray light source, the (Lu,A) ₃ Al ₅ O ₁₂ :Ce transparent ceramic scintillator has a luminous intensity of more than 7.5 times that of BGO and a decay time of less than 45ns.

In the present invention, before the transparent ceramic is polished, the cross-section is a square with a side length ranging from 10 to 50 mm and a thickness ranging from 1 mm to 4 mm.

In a preferred embodiment of the present invention, the length of the polished front side of the transparent ceramic is 20 mm, and the thickness range is 2 mm to 4 mm.

In the present invention, before the substrate is polished, the cross-section is a square with a side length ranging from 20 to 70 mm and a thickness ranging from 1 mm to 8 mm.

In a preferred embodiment of the present invention, the length of the polished front side of the substrate is 25mm, and the thickness ranges from 1mm to 4mm.

In the present invention, the transparent adhesive in the reflective layer fixes the transparent ceramic and the substrate.

In a preferred embodiment of the present invention, the transparent adhesive is silica gel.

In a preferred embodiment of the present invention, after the scintillator plate is ground and polished, the substrate thickness ranges from 0.5 mm to 4 mm.

In a preferred embodiment of the present invention, after the scintillator plate is ground and polished, the scintillator layer thickness ranges from 50 μm to 200 μm.

In the present invention, in order to improve the light collection efficiency of the scintillator layer in the scintillator plate, surface etching is required. After etching, the transparent ceramic surface is finally separated into multiple independent scintillator array units. Each independent array unit can be designed into different shapes according to actual needs. This etch process is also suitable for other bulk scintillator materials.

The preparation method of the invention can obtain transparent ceramics with high optical quality and excellent luminous performance, and the fixed scintillator plate can effectively absorb radiation and convert it into visible light. The process is simple, highly controllable, and repeatable, and is suitable for large-scale production.

FIG. 2 shows a schematic diagram of a scintillator plate of an example of the present invention. It can be seen from the figure that the scintillator plate is composed of a substrate, a reflective layer and a scintillator layer. The rays reach the scintillator layer through the reflective layer of the substrate, and are absorbed by the scintillator layer and converted into visible light. In Fig. 1, the upper layer is the substrate, the middle layer is the reflective layer and the lower layer is the scintillator layer, but it should be understood that in the present invention, the placement direction of the scintillator plate is not limited, and a three-layer structure of left, middle and right is also possible. composition. However, it must be ensured that the ray is incident on the substrate and exits from the scintillator layer.

Among them, the thickness range of the substrate: 0.05mm-10mm, preferably: 0.05mm-4mm, more preferably 0.5mm-4mm; the thickness range of the reflective layer: 0.01μm-0.5μm, preferably: 0.01μm-0.2μm; the scintillator layer Thickness range: 50 μm˜500 μm, preferably: 50 μm˜200 μm.

Fig. 3 shows an X-ray-excited luminescence spectrum of (Lu,A) ₃ Al ₅ O ₁₂ :Ce transparent ceramic scintillator of the present invention, and a BGO single crystal of the same size grown by pulling method is used as a reference sample. It can be seen from the figure that (Lu,A) ₃ Al ₅ O ₁₂ : Ce transparent ceramics can effectively emit visible light at 510nm under the action of X-rays, and the steady-state luminous efficiency reaches 7.5 times that of BGO.

FIG. 4 shows an optical microscope photo of (Lu,A) ₃ Al ₅ O ₁₂ :Ce transparent ceramic scintillator after surface etching in an example of the present invention. It can be seen from the figure that the surface-etched transparent ceramic scintillator is divided into rectangular arrays with a side length of 50 μm, and the spacing of the rectangular arrays is 10 μm. The transparent ceramic scintillator after surface etching forms a waveguide transmission on the surface to reduce total reflection loss, thereby improving the visible light collection efficiency of the device and increasing the spatial resolution of the system.

Technical effect of the present invention is as follows;

1. The present invention adopts (Lu,A) ₃ Al ₅ O ₁₂ :Ce transparent ceramics with high optical quality and high luminous efficiency as the scintillator, and develops a radiation flat panel detector system with high spatial resolution. The system has high imaging quality under X-ray excitation, and the pictures are clear and sharp. The MTF at 10lp/mm is above 17.5% by the lead wire-to-card method. Using the knife-edge method to test the RQA5 experimental conditions stipulated in the standard IEC62220-1, when the MTF is 10%, the resolution is above 9lp/mm;

2. The use of chemically stable garnet ceramics as the scintillator can effectively increase the service life of the detector and reduce device packaging and maintenance costs;

3. Taking advantage of the excellent processing performance of ceramics, the transparent ceramic scintillators are cut into rectangular arrays to form a waveguide transmission on the surface of the ceramics, reducing the light loss caused by total reflection, thereby improving the collection efficiency of the device and increasing the spatial resolution of the system.

Examples are given below to describe the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention, and should not be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art according to the above contents of the present invention all belong to the present invention scope of protection. The specific process parameters and the like in the following examples are only examples of suitable ranges, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not limited to the specific values exemplified below.

Example 1

Using lutetium oxide (Lu ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), magnesium oxide (MgO), and cerium oxide (CeO ₂ ) as raw materials, the composition is accurate according to (Lu _0.995 Ce _0.003 Mg _0.002 ) ₃ Al ₅ O ₁₂ Weigh 60g of the powder raw material, and then use absolute ethanol as the dispersion medium for ball milling and mixing. After ball milling for a certain period of time, the two powders are dried and sieved respectively; then they are pressed into tablets and subjected to 200MPa cold isostatic pressing Become a green body; put it into a vacuum or hot-press sintering furnace and sinter at 1880°C for 20 hours to obtain (Lu _(1-xy) C _x Mg _y ) ₃ Al ₅ O ₁₂ ceramics, and the obtained ceramics The material is polished to obtain a transparent ceramic with high optical quality. The transparent ceramics were ground, polished and cut to 20×20×2 mm. The linear transmittance of the transparent ceramic reaches 73% at 800nm, and the luminous intensity reaches 7.5 times that of BGO single crystal. The transparent ceramics and the substrate of 25×25×4 mm are bonded and fixed by silica gel mixed with dispersed particles. The scintillator plate is obtained by etching the polished and polished surface of the composite structure. The thickness of the processed scintillator layer is 50 μm, and its surface is a rectangular array of 50×50 μm with a pitch of 10 μm. Connect the incident light source, scintillator plate, light cone, and CCD as shown in Figure 1 to prepare (Lu,A) ₃ Al ₅ O ₁₂ :Ce transparent ceramic scintillator flat panel detectors. The MTF of the flat panel detector is 17.5% at 10lp/mm by the lead-to-card method, and the resolution is 9lp/mm when the MTF is 10% when the MTF is 10%.

Example 2

When preparing the scintillator plate, the thickness of the scintillator layer was 50 μm, but laser cutting was not performed, and other conditions were the same as in Example 1. The flat-panel detector adopts the lead wire-to-card method to test the MTF at 10lp/mm, and the MTF is 13.0%. The knife-edge method is used to test the RQA5 experimental conditions specified in the standard IEC62220-1. When the MTF is 10%, the resolution is 6lp/mm.

Example 3

According to the chemical composition of (Lu _0.997 Ce _0.001 Mg _0.002 ) ₃ Al ₅ O ₁₂ , 60 g was accurately weighed, and other conditions were the same as in Example 1, and (Lu _0.997 Ce _0.001 Mg _0.002 ) ₃ Al ₅ O ₁₂ transparent ceramics could be obtained. The in-line transmittance of the prepared ceramics can reach 75% after polishing, and the luminous intensity can reach 5 times that of BGO single crystal.

Example 4

According to the chemical composition of (Lu _0.996 Ce _0.002 Mg _0.002 ) ₃ Al ₅ O ₁₂ , 60 g was accurately weighed, and other conditions were the same as in Example 1, and (Lu _0.996 Ce _0.002 Mg _0.002 ) ₃ Al ₅ O ₁₂ transparent ceramics could be obtained. The in-line transmittance of the prepared ceramics reaches 77% after polishing, and the luminous intensity reaches 5 times that of BGO single crystal.

Example 5

According to the chemical composition of (Lu _0.994 Ce _0.004 Mg _0.002 ) ₃ Al ₅ O ₁₂ , 60 g was accurately weighed, and other conditions were the same as in Example 1, and (Lu _0.994 Ce _0.004 Mg _0.002 ) ₃ Al ₅ O ₁₂ transparent ceramics could be obtained. The in-line transmittance of the prepared ceramics reaches 67% after polishing, and the luminous intensity reaches 8.7 times that of BGO single crystal.

Example 6

Accurately weigh 60g according to the chemical composition of (Lu _0.9968 Ce _0.002 Mg _0.0012 Li _0.0006 ) ₃ Al ₅ O ₁₂ , and select LiOH·H ₂ O as the co-doped ion oxide. Other conditions are the same as in Example 1, and (Lu _0.9968 Ce _0.002 Mg _0.0012 Li _0.0006 ) ₃ Al ₅ O ₁₂ transparent ceramics. The in-line transmittance of the prepared ceramics reaches 71% after polishing, and the luminous intensity reaches 9.0 times that of BGO single crystal.

Industrial Applicability: The (Lu,A) ₃ Al ₅ O ₁₂ :Ce transparent ceramic ray flat panel detector of the present invention has the characteristics of sharp imaging and high spatial resolution, and has the advantages of low maintenance cost, long service life and maintenance cost. It is used in devices using radiation detection such as medical diagnosis, non-destructive testing, public safety, radiation dose detection and oil exploration. Designing the material microstructure by surface etching can effectively improve the imaging resolution of the system, and is applicable to all bulk scintillator materials.

Claims (17)

1. a kind of ray detection flat panel detector scintillator panel, which is characterized in that the scintillator panel includes substrate, scintillator Layer and it is clipped in shining and fixed substrate and scintillator with increasing scintillator panel between the substrate and scintillator layers The reflecting layer of the effect of layer, wherein the constitutional chemistry formula of the scintillator layers is (Lu_(1-x-y)Ce_xA_y)₃Al₅O₁₂, A case for The ion of selection includes Ca²⁺、Mg²⁺、Sr²⁺、Ba²⁺、Li⁺、 Na⁺、K⁺At least one of, 0.001≤x≤0.05,0.0005≤ y≤0.05；

There is the independent array element formed by etching on the surface of the scintillator layers, and array element is rectangular array unit, The side length of the rectangular array unit is 50 μm~200 μm, 10~20 μm of spacing range, 10~50 μm of etching depth.

2. scintillator panel according to claim 1, which is characterized in that A case ion is Mg²⁺；0.001≤x≤0.01； 0.0005≤y≤0.01。

3. scintillator panel according to claim 2, which is characterized in that 0.002≤x≤0.005.

4. scintillator panel according to claim 2, which is characterized in that 0.001≤y≤0.005.

5. scintillator panel according to claim 1, which is characterized in that the substrate material include graphite, resin, glass or Metal, the reflecting layer material include silica gel or epoxy resin.

6. scintillator panel according to claim 1, which is characterized in that scattered in reflector material containing 40~95 wt% light Particle SiO₂Particle.

7. scintillator panel according to claim 1, which is characterized in that substrate with a thickness of the mm of 0.05 mm~10, reflection Layer with a thickness of 0.01 μm~0.5 μm, scintillator layers with a thickness of 50 μm~500 μm.

8. any scintillator panel in -7 according to claim 1, which is characterized in that substrate with a thickness of 0.05 mm~4 Mm, reflecting layer with a thickness of 0.01 μm~0.2 μm, scintillator layers with a thickness of 50 μm~200 μm.

9. scintillator panel according to claim 8, which is characterized in that substrate with a thickness of the mm of 0.5 mm~4.

10. the preparation method of any scintillator panel in a kind of claim 1-9 characterized by comprising

1) solid reaction process or liquid phase method combination ceramic sintering technology, preparation flashing are used according to the constitutional chemistry formula of scintillator layers Body layer material；

2) scintillator layers material prepared by step 1) is cut into the scintillator layers thin slice of predetermined size；

3) it after fixing scintillator layers thin slice and substrate by reflector material, is polishing to specific thickness and polishes.

11. preparation method according to claim 10, which is characterized in that before the polishing of scintillator layers thin slice, cross section is square Shape, 10~50 mm of side size range, thickness range 1 mm~4 mm；

Before substrate polishing, cross section is rectangle, 20~70 mm of side size range, thickness range 1 mm~8 mm.

12. preparation method described in 0 or 11 according to claim 1, which is characterized in that the preparation method further include:

4) surface for etching the scintillator layers, forms it into array element, wherein the mode of etching includes: wire cutting, laser Cutting or inductively coupled plasma body.

13. a kind of flat panel detector containing the scintillator panel any in claim 1-9, which is characterized in that the plate Detector includes scintillator panel, light cone and electrooptical device.

14. the crystalline ceramics that any scintillator panel uses in a kind of claim 1-9, which is characterized in that the transparent pottery The constitutional chemistry formula of porcelain is (Lu_(1-x-y)Ce_xA_y)₃Al₅O₁₂, the alternative ion of A case includes Ca²⁺、Mg²⁺、Sr²⁺、Ba²⁺、 Li⁺、 Na⁺、K⁺At least one of, 0.001≤x≤0.01,0.0005≤y≤0.01.

15. a kind of preparation method of crystalline ceramics described in claim 14 characterized by comprising

1) it prepares mixed uniformly comprising luteium oxide, aluminium oxide, cerium oxide and the material powder for being co-doped with ion-oxygen compound；

2) biscuit of ceramics will be obtained after material powder molding；

3) by biscuit of ceramics, vacuum-sintering obtains the crystalline ceramics at 1700-1900 DEG C.

16. preparation method according to claim 15, which is characterized in that molding using dry-pressing formed or isostatic cool pressing at Type, wherein dry-pressing formed is dry-pressing 1~5 minute at 50~150 MPa, and isostatic cool pressing is cold etc. at 200~400 MPa Static pressure 1~10 minute.

17. preparation method according to claim 15 or 16, which is characterized in that the vacuum-sintering is in pressure≤10^-2 Keep the temperature 10 hours in 1700~1820 DEG C under the vacuum degree of Pa or more.