KR20210013803A - Curved Radiation Detector Using Flexible Grid - Google Patents

Abstract

The present invention relates to a curved radiation detector using a flexible grid. According to the present invention, the radiation detector substitutes an existing planar detector by the curved detector to sense an image of an affected area at high sensitivity without inconvenience of rephotographing to maximize convenience of a patient and uses the curved grid for restraining scattering of radiation so as to be capable of providing the clear high resolution image.

Description

Curved Radiation Detector Using Flexible Grid

The present invention relates to an indirect digital radiation detector, and in particular, to a curved high-resolution radiation detector that minimizes image distortion using a flexible grid as a radiation image sensor such as X-ray.

The indirect digital radiation detector is a scintillator that generates visible light by absorbing radiation such as X-rays, and a CMOS (Complementary Metal Oxide Semiconductor) and CCD (Charge) including a photodiode (PD) for reading the generated visible light as an electrical signal. Coupled Device) and other image sensors. Various powdered phosphors, such as Gd2O2S(Tb) and Gd2O2(Eu) materials having a thickness of tens to hundreds of μm, are being tried as scintillators used for indirect radiation detectors, and also reduce the spread of light to reduce space. As a scintillator to improve resolution, a microstructured phosphor formed in a column or needle shape through physical vapor deposition (PVD) has been attempted.

Even if a scintillator having a needle columnar microstructure is used, since light spreading still exists, a method for more completely preventing light scattering is required. In addition, a pixel structure is first fabricated through a deep reactive ion etching (RIE) process of a silicon wafer or a PDP (Plasma Display Panel) barrier structure process for an insulator on the glass, and then scintillation material powder in the grooves of the pixels divided by the barrier ribs. There is a research on realizing clear image quality using a pixel structure type scintillator by mixing and filling with a paste or dissolving and solidifying the powder.

Since visible light generated in the powder scintillator decreases the spatial resolution of the image through scattering, as a countermeasure for this, light generated in the scintillator is formed by forming a microstructure of a columnar structure through physical vapor deposition equipment. This is how to minimize the spread of The scintillator used here should be a material with high atomic number and density such as CsI(Na) or CsI(Tl), and the wavelength of emitted visible light should be a photoconductor below and a doping material with good quantum efficiency.

However, even if a scintillator having a fine structure in the form of a needle column is used, light spreading still exists, so a method of preventing perfect light scattering is required. In addition, in the method of using the conventional pixel structure type scintillator, there is a problem that the resolution is improved but the sensitivity is decreased. In addition, in some cases, a fiber optic plate (FOP) material is inserted between the scintillator and the photodiode to block X-rays transmitted to the photodiode without being absorbed by the scintillator, but there is a problem that requires high cost. .

However, the conventional indirect digital radiation detector uses a stiff solid flat sensor, so the resolution of the image varies for each patient according to the size or shape of the body, so it is inconvenient to retake the image. The distortion of the resulting image is a problem that needs to be continuously improved.

As related documents, reference may be made to US patents US 2016/0370303A1, US 2017/0003401A1, WO2015099422A1, and the like.

Accordingly, the present invention was conceived to solve the above-described problems, and an object of the present invention is to replace the existing flat detector with a curved detector to sense high sensitivity for an affected area image without the inconvenience of re-taking. The goal is to provide a curved radiation detector capable of providing clear, high-resolution images by employing a curved grid to suppress radiation scattering and maximizing patient convenience.

First, summarizing the features of the present invention, a radiation detector according to an aspect of the present invention for achieving the above object includes: a curved or flexible image sensor substrate having a plurality of pixel sensors in an array form; A curved or flexible scintillator structure provided on the image sensor substrate and configured to receive radiation and convert it into visible light; And a curved or flexible grid for increasing the contrast of the image by removing the influence of scattered radiation, wherein the image sensor substrate is for reading an electrical signal proportional to the visible light from each pixel, and the scintillator structure , It is characterized in that the entire structure including the image sensor substrate, the scintillator structure, and the grid is formed to be curved or flexible by being formed in a curved or flexible manner by a direct formation method.

The image sensor substrate may be made of a curved or flexible plastic substrate having a circuit array formed thereon.

The image sensor substrate may be manufactured as a curved or flexible substrate by etching or polishing the rear surface of the glass substrate after forming a circuit array on a curved or flexible glass substrate, or after forming a circuit array on a glass substrate. have.

The image sensor substrate may include a photodiode to read an electrical signal proportional to the visible light from each pixel.

The grid includes a scintillator pixel array formed by laser processing on a scintillator sheet, separated by an air gap.

The grid may include a scintillator pixel array formed by processing by a sawing device on the scintillator sheet, separated by an air gap.

The scintillator pixel array includes a structure in which a horizontal or vertical pitch of pixels is 30 to 500 μm, and a separation distance between pixels is 2 to 50 μm.

The grid may further include a permeable material applied to the air gap.

The scintillator may include a GOS (Gd2O2S:Tb) or a CsI:Tl scintillator.

In addition, according to another aspect of the present invention, a method of manufacturing a radiation detector includes: manufacturing a curved or flexible image sensor substrate having a plurality of pixel sensors in an array form; Forming a curved or flexible scintillator structure by a method formed directly on the image sensor substrate; And forming a curved or flexible grid on the scintillator structure to increase the contrast of the image by removing the influence of the scattered radiation, wherein the scintillator structure receives the radiation and converts it into visible light, and the image sensor substrate, For reading an electrical signal proportional to the visible light from each pixel, the entire structure including the image sensor substrate, the scintillator structure, and the grid is formed in a curved or flexible shape.

The curved radiation detector according to the present invention can maximize the convenience of the patient by sensing high sensitivity for the affected area image without the inconvenience of re-taking by replacing the existing flat detector with a curved detector. By employing a curved grid to suppress scattering, it is possible to provide a clear, high-resolution image.

The accompanying drawings, which are included as part of the detailed description to aid understanding of the present invention, provide embodiments of the present invention and describe the technical spirit of the present invention together with the detailed description.
1 is a view for explaining an example of an indirect digital radiation detector using a curved or flexible grid of the present invention.
2 is a view for explaining the formation of a curved or flexible grid in the indirect digital radiation detector according to an embodiment of the present invention.
3 is a view for explaining various forms of the scintillator pixel array of the grid of the present invention.
4 is a flowchart illustrating a manufacturing process of the indirect digital radiation detector of the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. In this case, the same components in each drawing are indicated by the same reference numerals as possible. In addition, detailed descriptions of functions and/or configurations already known are omitted. In the following, a part necessary for understanding an operation according to various embodiments will be mainly described, and a description of elements that may obscure the subject matter of the description will be omitted. In addition, some elements in the drawings may be exaggerated, omitted, or schematically illustrated. The size of each component does not entirely reflect the actual size, and therefore, the contents described herein are not limited by the relative size or spacing of the components drawn in each drawing.

In describing the embodiments of the present invention, when it is determined that a detailed description of a known technology related to the present invention may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted. In addition, terms to be described later are terms defined in consideration of functions in the present invention and may vary according to the intention or custom of users or operators. Therefore, the definition should be made based on the contents throughout this specification. The terms used in the detailed description are merely for describing the embodiments of the present invention, and should not be limiting. Unless explicitly used otherwise, expressions in the singular form include the meaning of the plural form. In this description, expressions such as "comprising" or "feature" are intended to refer to certain features, numbers, steps, actions, elements, some or combination thereof, and one or more It should not be construed to exclude the presence or possibility of other features, numbers, steps, actions, elements, any part or combination thereof.

In addition, terms such as first and second may be used to describe various components, but the components are not limited by the terms, and the terms are used to distinguish one component from other components. Is only used.

1 is a view for explaining an example of an indirect digital radiation detector 100 using a curved or flexible grid of the present invention. Referring to Figure 1, the indirect type digital radiation detector 100 according to an embodiment of the present invention, a curved or flexible image sensor substrate 110, a curved or flexible scintillator structure 120, and a curved or flexible It includes a grid 130.

The scintillator structure 120 is provided on the curved or flexible image sensor substrate 110, and may be formed in a curved or flexible manner by being formed directly on the structure itself. The grid 130 has a structure in which a radiation absorbing part (eg, Pb, etc.) and a radiation transmitting part (eg, Al, Carbon, wood, etc.) are alternately and repeatedly arranged to increase the contrast of the image by removing the effect of the incident scattered radiation. In addition, a curved or flexible structure may be attached or bonded on the scintillator structure 120, and in particular, a scintillator sheet made of GOS (Gd2O2S:Tb) or CsI:Tl scintillator, etc., is bonded to the scintillator structure 120. It may be formed to include a one-dimensional or two-dimensional scintillator pixel array divided by the post-processed air gap 131 and configured to be curved or flexible. At this time, a GOS (Gd2O2S:Tb) or a CsI:Tl scintillator may serve as a radiation absorbing part, and the air gap 131 may serve as a radiation transmitting part. As a result, in the indirect digital radiation detector 100 according to an embodiment of the present invention, the entire structure including the image sensor substrate 110, the scintillator structure 120, and the grid 130 is formed in a curved or flexible manner. .

Such an indirect digital radiation detector 100 according to an embodiment of the present invention diagnoses the condition of various affected areas or lesions (eg, bone fractures, cracks, etc.) of the patient 20 such as the head, chest, pelvis, and knees. In order to do so, radiation 50 such as X-rays and gamma rays may be irradiated to teeth in the oral cavity and used in a radiographic apparatus for obtaining a corresponding image. The indirect digital radiation detector 100 according to an embodiment of the present invention is preferably applied mainly to a low-cost large-area radiographic apparatus, but in some cases, dental oral radiation for detecting radiation transmitted through the teeth in the oral cavity It may be manufactured and used in a small size such as a detector.

When radiation such as X-rays and gamma rays is incident on the grid 130, the scintillators of the scintillator structure 120 are converted into visible light and emitted to the image sensor substrate 110. Some radiation may pass through the scintillator of the scintillator structure 120 and be directly emitted to the image sensor substrate 110. However, in order to block radiation such as X-rays reaching the image sensor substrate 110, a fiber optic plate (FOP) material may be inserted between the scintillator structure 120 and the image sensor substrate 110. Radiation such as X-rays incident on the scintillation material of the scintillator structure 120 having a certain band gap (E _g ) excites the scintillation material and raises the electrons in the valence band through the exciton band to the conduction band. It is possible to emit visible light in a wavelength range of 200 to 600 nm when is lowered to a low energy state through a trap or an activation center.

In FIG. 1, the image sensor substrate 110 includes a plurality of pixel sensors in the form of a one-dimensional or two-dimensional array, and each pixel sensor reads an electrical signal proportional to the visible light arriving at each pixel. It can be made in an indirect manner including a photodiode. The circuit array 112 of the image sensor substrate 110 reads out an electrical signal output through the photodiode. However, in some cases, the image sensor substrate 110 includes a photoconductor layer (not shown), and each pixel sensor uses the circuit array 112 of the image sensor substrate 110 to generate electron-holes in the photoconductor layer. It may be driven in a hybrid method of reading an electrical signal corresponding to. In order to operate as a small dental oral radiation detector, it is desirable to be driven in an indirect manner without a photoconductor layer as described above, since it must realize high speed, high sensitivity, and high resolution at a low dose.

Hereinafter, a manufacturing process and principle of the indirect digital radiation detector 100 according to an embodiment of the present invention will be described in more detail with reference to the drawings of FIGS. 1 to 3 and the process flow diagram of FIG. 4.

4 is a flowchart illustrating a manufacturing process of the indirect digital radiation detector 100 of the present invention.

Referring to FIG. 4, first, a curved or flexible image sensor substrate 110 having a plurality of pixel sensors in an array form is manufactured (S110).

1 to 3, the curved or flexible image sensor substrate 110 includes a plurality of pixel sensors in the form of a one-dimensional or two-dimensional array, and for this purpose, an image on a curved or flexible plastic or glass substrate 111 A photodiode and a circuit array 112 formed in a one-dimensional or two-dimensional array to correspond to each pixel sensor of the sensor substrate 110 are included. A protective layer, such as a transparent insulating film, may be included on the circuit array 112 to transmit visible light from the scintillator structure 120. In addition, the image sensor substrate 110 is formed into a curved or flexible substrate by etching or polishing the rear surface of the glass substrate 111 after forming the circuit array 112 on a thick glass substrate 111 that lacks flexibility. May be.

Here, the circuit array 112 includes a circuit array such as a TFT (Thin Film Transistor) array or a CCD (Charge Coupled Device) array formed in a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) structure using amorphous silicon as an active layer. can do. However, it is preferable to be driven in a CMOS (Complementary Metal Oxide Semiconductor) circuit array 112 method because it is required to realize high speed, high sensitivity, and high resolution with low dose in order to operate as a dental oral radiation detector.

Next, the scintillator structure 120 is directly formed on the image sensor substrate 110 (S120).

As a first example, the scintillator structure 120 is a CsI:Tl scintillator or the like (in some cases, YAG:Ce, LuAG:Ce, LSO:Tb, LYSO, GSO, BGO, or GAGG) on the image sensor substrate 110 It can be formed by directly coating a scintillator such as) using a vacuum evaporation equipment. For example, a single crystal or polycrystalline scintillator structure may be formed on the image sensor substrate 110 by using a growth method such as a Czochralski method, a Bridgeman method, and a Liquid Phase Epitaxy (LPE) method. Accordingly, since there are not many grain boundaries, there is no scattering of light, that is, the resolution of an image can be greatly improved. Since such a single crystal/polycrystalline structure has a high density, it may not require an additional FOP for X-ray shielding because it absorbs a lot of radiation such as X-rays.

As another example, the scintillator structure 120 is a scintillator such as GOS (Gd2O2S:Tb) (in some cases, a scintillator such as YAG:Ce, LuAG:Ce, LSO:Tb, LYSO, GSO, BGO, or GAGG may be used) The particles may be formed in a paste form and then coated by spraying or screen printing. Scintillator particles such as GOS (Gd2O2S:Tb) may be in the form of microparticles or nanopowder. The nanopowder form may be obtained through crushing or grinding a powder having a size within a few micrometers, or by synthesizing a nanopowder. When using a scintillator having a micrometer size, since the scattering of light within the scintillator is very high, the final image resolution may be degraded due to blurring, but the use of nano powders has a much higher resolution. Video implementation becomes possible.

Although the scintillator structure 120 may be individually manufactured in a curved or flexible manner and attached to the sensor through a pressing process, it is particularly preferable that the scintillator structure 120 is formed directly on the image sensor substrate 110 in the present invention. When a curved surface is formed by such a direct growth or coating method, there is an advantage in that distortion can be prevented and there is no need for alignment. In addition, when coating directly compared to the existing process, the amount of visible light emission and resolution can be improved.

2 is a diagram for explaining the formation of a curved or flexible grid 130 in the indirect digital radiation detector 100 according to an embodiment of the present invention.

2, the grid 130 is a one-dimensional divided by an air gap 131 processed after bonding a scintillator sheet made of GOS (Gd2O2S:Tb) or CsI:Tl scintillator to the scintillator structure 120 Alternatively, it may be formed to include a two-dimensional scintillator pixel array and configured to be curved or flexible (S130). At this time, a GOS (Gd2O2S:Tb) or a CsI:Tl scintillator may serve as a radiation absorbing part, and the air gap 131 may serve as a radiation transmitting part. As a result, in the indirect digital radiation detector 100 according to an embodiment of the present invention, the entire structure including the image sensor substrate 110, the scintillator structure 120, and the grid 130 is formed in a curved or flexible manner. .

Here, the processing of the air gap 131 may be performed by processing the scintillator sheet with a semiconductor sawing equipment, or by a picosecond or femtosecond pulse laser irradiated from the laser generator 10 to the scintillator sheet as shown in FIG. It can also be formed by processing. It may be a form including a one-dimensional or two-dimensional scintillator pixel array divided by the air gap 131. Through this, it is possible to increase the contrast of the image by removing the influence of the incident scattered radiation. The scintillator pixel array divided by the air gap 131 may be formed as, for example, a plurality of horizontal arrays (a), a plurality of vertical arrays (b), or a grid array (c), as shown in FIG. 3. .

For example, in the case of using a sawing device or laser, a pixel horizontal/vertical pitch of about 30 to 500 μm (e.g., 50 μm, 100 μm, 150 μm, 200 μm), a separation distance between pixels (interval) of about 2 to 50 μm, square , Rectangle, honeycomb, linear, circular, etc. It is possible to micro-machining to form various pixel shapes designed for the application field. For example, lasers of appropriate power, such as various picosecond or femtosecond pulsed lasers of tens to hundreds of watts or tens to hundreds of mJ high power energy, for example, excimer lasers, semiconductor (e.g., GaAs) lasers, gas lasers ( For example, a CO ₂ laser) or a solid state laser (eg, Nd:YAG) may be used to perform a patterning etching process for the scintillator pixel array.

If necessary, a permeable material such as Al or Carbon may be applied to the air gap 131 formed as above. Although the effect of scattered radiation can be reduced with only the air gap as described above, a transparent material such as Al or Carbon may be applied (or coated) to the air gap 131. For example, the air gap can be selectively applied using a semiconductor process by vacuum deposition equipment for CVD (chemical vapor deposition), and in some cases, the permeable material can be applied by spraying. have.

As described above, the indirect type oral radiation detectors 100 and 200 according to the present invention form the scintillator structure 120 directly formed on the curved or flexible image sensor substrate 110, thereby preventing the existing planar detector. By replacing it with a curved detector, it is possible to maximize the convenience of the patient by sensing high sensitivity to the affected area image without the inconvenience of re-taking, and by configuring the grid 130 comprising the air gap 131 on the scintillator sheet. By suppressing the scattering of radiation, it is possible to provide a clear, high-resolution image.

As described above, in the present invention, specific matters such as specific components, etc., and limited embodiments and drawings have been described, but this is provided only to help a more general understanding of the present invention, and the present invention is not limited to the above embodiments , Anyone having ordinary knowledge in the field to which the present invention belongs will be able to make various modifications and variations without departing from the essential characteristics of the present invention. Therefore, the spirit of the present invention is limited to the described embodiments and should not be defined, and all technical ideas that have equivalent or equivalent modifications to the claims as well as the claims to be described later are included in the scope of the present invention. Should be interpreted as.

Image sensor (110)
Substrate (111)
Circuit Array(112)
Scintillator structure(120)
Grid (130)

Claims (10)

A curved or flexible image sensor substrate having a plurality of pixel sensors in the form of an array;
A curved or flexible scintillator structure provided on the image sensor substrate and configured to receive radiation and convert it into visible light; And
It includes a curved or flexible grid to increase the contrast of the image by removing the effect of scattered radiation,
The image sensor substrate is for reading an electrical signal proportional to the visible light from each pixel,
The scintillator structure is formed in a curved or flexible manner by a direct formation method,
The radiation detector, characterized in that the entire structure including the image sensor substrate, the scintillator structure, and the grid is curved or flexible. The method of claim 1,
The image sensor substrate is a radiation detector, characterized in that made of a curved or flexible plastic substrate on which a circuit array is formed. The method of claim 1,
The image sensor substrate is manufactured as a curved or flexible substrate by etching or polishing the rear surface of the glass substrate after forming a circuit array on a curved or flexible glass substrate, or after forming a circuit array on a glass substrate. Radiation detector characterized by. The method of claim 1,
And the image sensor substrate includes a photodiode to read an electrical signal proportional to the visible light from each pixel. The method of claim 1,
The grid,
Scintillator pixel array formed by laser processing on scintillator sheet, separated by air gap
Radiation detector comprising a. The method of claim 1,
The grid,
Scintillator pixel array formed by processing by sawing equipment on the scintillator sheet, separated by air gaps
Radiation detector comprising a. The method of claim 5 or 6,
The scintillator pixel array,
A radiation detector comprising a structure having a horizontal or vertical pitch of a pixel of 30 to 500 μm and a separation distance between pixels of 2 to 50 μm. The method of claim 5 or 6,
The grid,
A radiation detector further comprising a transmissive material applied to the air gap. The method of claim 5 or 6,
The scintillator is a radiation detector comprising a GOS (Gd2O2S:Tb) or CsI:Tl scintillator. Manufacturing a curved or flexible image sensor substrate having a plurality of pixel sensors in the form of an array;
Forming a curved or flexible scintillator structure by a method formed directly on the image sensor substrate; And
And forming a curved or flexible grid on the scintillator structure to increase the contrast of the image by removing the influence of the scattered radiation,
The scintillator structure receives radiation and converts it into visible light, and the image sensor substrate is for reading an electrical signal proportional to the visible light from each pixel,
A method of manufacturing a radiation detector, wherein the image sensor substrate, the scintillator structure, and the entire structure including the grid are curved or flexible.

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