KR20020060639A - Digital x-ray detecting plate with fluorescent module - Google Patents

Abstract

PURPOSE: A digital printed circuit board for detecting X-ray including fluorescent module is provided to convert X-ray into visible ray and detect reactionary property of an X-ray receptor to the visible ray. CONSTITUTION: A printed circuit board comprises an X-ray receptor layer(200) generating pairs of electrons and positive holes by X-ray; electrode layers(300,400) formed on an upper surface and a lower surface of the X-ray receptor layer; a thin film transistor(TFT) base plate layer(100) acting as a physically supporting base for the X-ray receptor layer; and a lead-out device converting electric signal of the X-ray receptor layer into visual information and includes a fluorescent module(500), mounted on the printed circuit board to be replaceable and comprising a base, being a physical support; a fluorescent layer applied on the base and generating visible light by X-ray; and a reflective layer, formed on the fluorescent layer and reflecting visible light generated in the fluorescent layer.

Description

DIGITAL X-RAY DETECTING PLATE WITH FLUORESCENT MODULE}

The present invention relates to an X-ray detector plate including a fluorescent module, and more particularly, an upper and lower surfaces of an X-ray receptor layer and an X-ray receptor layer generating electrons and hole pairs by X-rays. Moving picture digital X-detecting an X-ray comprising an electrode layer formed on the substrate, a substrate layer which is a physical support base of the X-ray receptor layer, and a readout device for converting an electrical signal of the X-ray receptor layer into image information. A ray detector plate, comprising: a base, which is a physical support; A fluorescent layer coated on the base and generating visible light by X-rays; The present invention relates to a digital X-ray detector plate comprising a fluorescent module mounted on the X-ray detector plate in an exchangeable manner, the reflection layer being formed on the fluorescent layer to reflect visible light generated from the fluorescent layer.

In addition, the fluorescent layer is a calcium tungstate or rare earth-based fluorescent material or CsI (Tl), CsI (Na), NaI (Tl), ZnS, ZnS (Ag), ZnCdS, ZnCdS that generates light in response to X-rays (Ag), Gd ₂ O ₂ S (Tb) relates to an X-ray detector plate comprising a fluorescent module characterized in that the material layer.

In general, a digital X-ray detector plate is an X-ray detection apparatus that detects X-rays penetrating the human body and obtains image information. Mean panel.

Hereinafter, a digital x-ray detector plate according to the prior art will be described.

X-ray detector plate has been actively digitized, but the background of digitization of X-ray detector plate has been able to obtain image quality comparable to analog system, lowered price of imaging equipment, image storage and transmission. This is because there are various advantages obtained by the use of the system, and has been developed as an X-ray image sensor, a scanning laser, an image processing system by an indirect image reading sensor by LEDs, and the like.

In the prior art method, the digital X-ray detector plate is an X-ray receptor layer and an X-ray receptor layer formed on the upper and lower surfaces of the X-ray receptor layer and the X-ray receptor layer for generating electrons and hole pairs by X-rays. And a readout device for converting the electrical signal of the X-ray receptor layer formed on the substrate layer, which is a physical support base, into image information.

Meanwhile, the digital X-ray detector plate of the prior art is divided into a direct method and an indirect method according to a method of converting an X-ray into an electrical signal.

Hereinafter, two methods of the conventional X-ray detector plate will be described with reference to the accompanying drawings.

5 is a cross-sectional conceptual view of a conventional digital X-ray detector plate of the direct method, and FIG. 6 is a cross-sectional conceptual view of a conventional digital X-ray detector plate of the indirect method.

As shown in FIG. 5, the direct digital X-ray detector plate forms a blocking layer T7 on top of the X-ray receptor T6 and attaches an application electrode T2 on top thereof. The base cell is formed by uniting the collection electrode T1 and the dielectric layer and the TFT T5, which is a signal detection element, under the ray receptor T6, and the planar array of the unit cells is used to form a digital X-ray detector plate. To form.

When the X-ray is incident on the direct digital X-ray detector plate, the electrons of the X-ray receptor are excited to generate electrons and electron-hole pairs. At this time, strong electrons are applied through the upper applied electrode T2. When an electric field is formed, a flow of charge is generated due to the movement of electrons and holes due to the polarity.

This charge flow is accumulated in a signal storage capacitor through the collecting electrode T1, and the charge is read out as an electrical digital signal through the TFT, and the digital signal is used as a digital source of an image. You get a digital X-ray image.

As shown in FIG. 6, the indirect digital X-ray detector plate comprises an X-ray receptor C2 made of fluorescent material and a photodiode or the like under the X ray receptor C2. A unit cell having the light receiving element C1 attached thereto is a basic unit, and the digital X-ray detector plate is configured by the arrangement of the unit cells.

Indirect digital X-ray detector plate is an X-ray receptor that emits light by X-rays, and the light generated by the light-emitting phenomenon is electrically digital through a photodiode or the like. The signal is read out. When the digital signal is used as a digital source of an image, a digital X-ray image is obtained.

Among the conventional digital X-ray detector plates described above, the most common material constituting the X-ray receptor layer in the direct digital X-ray detector plate is a-Se.

By the way, when looking at the reaction characteristics of the a-Se of the X-ray receptor layer, it is clear that electrons and hole pairs are generated by X-rays, but more electrons and hole pairs are generated in the visible light region.

FIG. 4 is a chart measuring reaction characteristics of a-Se constituting the X-ray receptor layer, in which the horizontal axis represents absorption characteristics (reaction characteristics) in the wavelength band, and the upper line represents a reaction of a-Se (selenium). It is a characteristic curve and the lower line is the response characteristic of ITO (transparent electrode).

Referring to the reaction characteristics of the X-ray receptor layer as shown in FIG. 4, it can be seen that the response characteristics of the wavelength band corresponding to the visible light region (380 to 770 nm) are superior to those of the X-ray region.

However, the direct prior art digital X-ray detector plate has a weak response in the wavelength range of the X-ray (the wavelength range is usually about 3 to 10 nm) among the reaction characteristics of the X-ray receptor a-Se of FIG. Considering only the characteristics, there is a problem in that the reactivity is weak by manufacturing the X-ray detection device.

Therefore, the prior art digital X-ray detector plate manufactured by the direct method has a thickness of the X-ray receptor in order to obtain X-ray image information using only the weak X-ray region response characteristics of the X-ray receptor. In order to form a thicker and to amplify the reaction characteristics, there is a problem in that a high voltage power is applied through the electrodes on both ends of the X-ray receptor.

Specifically, in order to detect the weak radiation signal amount generated in the X-ray receptor layer (selenium layer), the voltage applied to the electrodes at both ends requires a high voltage of 10 V / μm, and the thickness of the X-ray receptor is several hundreds. Assuming that μm is required, a high voltage of several KV DC should be applied, which is an obstacle in designing the thickness of the X-ray receptor to improve the X-ray region response characteristics, and is caused by the breakdown of the X-ray receptor layer and the high voltage. There is a problem that causes damage to the TFT element.

In addition, the indirect method of the prior art digital X-ray detector plate is a method of forming a light receiving element in the unit cell constituting the substrate, there is a problem that it is difficult to manufacture the unit cell and high cost because the yield is low, X-ray receptor By configuring itself as a fluorescent layer, there is a problem that the direct reaction characteristics by X-rays are overlooked.

On the other hand, the development of the digital X-ray detector plate is inevitably progressed to a video or continuous image acquisition device such as an X-ray fluoroscopy apparatus or a mammography apparatus. However, the two types of digital X-ray detector plates of the prior art have a problem that the signal generation amount is small at a small dose and is inappropriate to be applied.

The present invention utilizes the response characteristics of the visible light region of the direct X-ray receptor material (a-Se) in order to solve the above problems, after converting the X-ray to visible light to the visible light It is an object of the present invention to provide a digital X-ray detector plate for detecting the response characteristics of the X-ray receptor for the device.

In addition, the design burden on the thickness of the X-ray receptor is reduced according to the reaction characteristics of the visible light region of the X-ray receptor layer, thereby lowering the applied voltage applied to the X-ray receptor, thereby insulating the X-ray receptor layer. It is an object of the present invention to provide a digital X-ray detector plate which prevents breakdown and damage of a TFT element due to high voltage.

Also, in order to acquire X-ray fluoroscopy or mammography images, it is possible to reduce the burden on the human body when continuously projecting X-rays on the human body, which is particularly useful for X-ray fluoroscopy or mammography. It is an object to provide a ray detector plate.

1 is a cross-sectional structure diagram of a digital X-ray detector plate including a fluorescent module according to the present invention

Figure 2 is a cross-sectional structure diagram of a digital X-ray detector plate comprising a fluorescent module according to the present invention

Figure 3 is a photograph of the results of the implementation of the digital X-ray detector plate comprising a fluorescent module according to the present invention

Figure 4 is a chart measuring the reaction characteristics of the a-Se constituting the X-ray receptor layer

Figure 5 is a cross-sectional view of a conventional digital x-ray detector plate of the direct method

6 is a conceptual diagram of a conventional digital X-ray detector plate of the indirect method

* Explanation of symbols on main parts of drawings *

100 TFT 150 TFT Transistor

200: X-ray receptor 300: electrode (upper electrode)

400: electrode (lower electrode) 500: fluorescent module

510: fluorescent layer 520: base

530: reflective layer

The present invention has been made to achieve the above object, the X-ray receptor layer for generating electrons and hole pairs by the X-ray and the electrode layer formed on the upper and lower surfaces of the X-ray receptor layer and the X-ray receptor A digital X-ray detector plate for detecting X-rays comprising a substrate layer, which is a physical support base of a layer, and a lead-out device for converting an electrical signal of the X-ray receptor layer into image information. A base; A fluorescent layer coated on the base and generating visible light by X-rays; The technical gist of the present invention is a digital X-ray detector plate including a fluorescent module that is formed on the fluorescent layer and includes a reflective layer that is alternately mounted on the X-ray detector plate.

Here, the fluorescent layer is a calcium tungstate or rare earth-based fluorescent material or CsI (Tl), CsI (Na), NaI (Tl), ZnS, ZnS (Ag), ZnCdS, ZnCdS that generates light in response to X-rays (Ag), it is preferable that the X-ray detector plate comprising a fluorescent module characterized in that the material layer of any one of Gd ₂ O ₂ S (Tb).

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional structural diagram of an X-ray detector plate including a fluorescent module according to the present invention, and FIG. 2 is a cross-sectional structural view of a fluorescent module of an X-ray detector plate including a fluorescent module according to the present invention. Is a photograph of the results of the implementation of the X-ray detector plate comprising a fluorescent module according to the present invention.

As shown in FIG. 1, the present invention relates to a digital X-ray detector plate, and includes an insulating layer (not shown) and a lower collection electrode 400 formed under the upper application electrode 300 and the upper application electrode 300. ), An X-ray receptor layer 200, and a fluorescent module 500 that is mounted interchangeably on a conventional digital X-ray detector plate composed of a readout device 100 formed on a substrate. .

The fluorescent module 500 includes a base 520 which is a physical support, a fluorescent layer 510 formed on the base 520, and a light emitting light of the fluorescent layer 510 formed on the fluorescent layer 510. It is composed of a reflective layer 530 for reflecting back.

The reason why the fluorescent layer is configured like the fluorescent module 500 is to form the fluorescent layer 510 in the conventional X-ray detector plate so as to be interchangeable.

The base 520 is preferably a substrate made of a transparent material so that visible light generated from the fluorescent layer 510 is transmitted, and polyester plastic is suitable.

The fluorescent layer 510 is formed of a material that generates visible light in response to X-rays, and mainly includes a phosphorus layer, calcium tungsten (CaWO ₄ ), and a rare earth phosphor.

In detail, the fluorescent layer 510 of the fluorescent module 500 is preferably made of a material that emits light in the same wavelength band as the reaction wavelength band that reacts with the X-ray to allow the most current to flow in the X-ray receptor. Suitable materials include CaWO4 or Rare earth based Gd series, La series, CsI (Tl), CsI (Na), NaI (Tl), ZnS, ZnS (Ag), ZnCdS, ZnCdS (Ag) And Gd ₂ O ₂ S (Tb).

Since the materials constituting the fluorescent layer are materials well known to generate visible light in response to X-rays, descriptions of reaction characteristics thereof will be omitted.

The reflective layer 530 is formed on the fluorescent layer 510 of the fluorescent module 500 to reflect back the light generated from the fluorescent layer, so that the change generated by the reaction is directed to the X-ray receptor layer. Improves response efficiency

The reflective layer 530 is made of a material that is widely known as a light reflecting material in a radiological area such as titanium dioxide, Al-based, and MgO.

It is preferable to form a plastic protective layer on the reflective layer 530 to protect the fluorescent module and maintain cleanliness.

Hereinafter, the function of the present invention having the above configuration will be described.

In the digital X-ray detector plate, the most common material constituting the X-ray receptor 200 layer is a-Se.

By the way, when looking at the reaction characteristics of the a-Se of the X-ray receptor 200 layer, it is obvious that electrons and hole pairs are generated by X-rays, but more electrons and hole pairs are generated in the visible light region.

Fig. 4 is a chart measuring the reaction characteristics of a-Se constituting the X-ray receptor layer, in which the horizontal axis represents the absorption band (response characteristic) in the wavelength band, and the upper line shows the reaction of a-Se (selenium). It is a characteristic curve and the lower line is the response characteristic of ITO (transparent electrode).

Referring to the reaction characteristics of the X-ray receptor layer as shown in FIG. 4, it can be seen that the response characteristics of the wavelength band corresponding to the visible light region (380 to 770 nm) are superior to those of the X-ray region.

The present invention uses the reaction characteristics of the visible light region of the X-ray receptor 200 material to convert the X-rays to visible light and then to use the reaction characteristics of the X-ray receptor 200 to the visible light. Make a point.

To this end, a fluorescent layer such as calcium tungstate or rare earth phosphor, which emits light in response to the X-ray, is formed on the upper side of the digital X-ray detector plate.

As described above, since the reactivity of the X-ray receptor 200 layer has better characteristics in the visible light region, the X-ray receptor 200 layer reacts with the visible light generated in the fluorescent layer to form an electron hole pair. The generated electrons and hole pairs are detected by the readout device 100 consisting of a collection electrode, a capacitor, and a transistor.

On the other hand, the response characteristics of the radiation region of the X-ray receptor 200 layer itself are maintained as it is, according to the present invention, the direct response of the X-ray receptor 200 layer to radiation and the X-ray to visible light with changed radiation. All of the indirect reactions of the ray receptor 200 layer are detected.

According to this, even a small amount of X-rays are detected by the TFT as X-rays and visible light by the fluorescent layer as independent electric signals, thereby increasing the detection efficiency.

Therefore, when used in an X-ray fluoroscopy apparatus or a mammography apparatus in which X-rays are incident for a long time, a large response signal is generated even when a small amount of X-rays are incident during a recording time, thereby reducing a human risk of exposure. .

On the other hand, the fluorescent layer 510 is formed in the form of a module because the luminous power is reduced when deterioration as the incident of the X-ray is repeated tens of thousands of times, it is preferable to configure the replaceable when damaged.

In detail, the fluorescent layer 510 is deteriorated when exposed to X-rays 15000-20000 times.

Therefore, the possibility of replacing the fluorescent layer 510 is essential for continuous image capturing, and by modularizing the fluorescent layer 510 into a replaceable form, an X-ray detector plate for moving picture or continuous image (specifically, X-ray perspective Imaging device or mammography device).

The fluorescent module included in the digital X-ray detector plate of the present invention includes a base 520 which is a physical support, a fluorescent layer 510 formed on the base, and a fluorescent layer formed on the fluorescent layer 510. It is composed of a module consisting of a reflective layer 530 that reflects the emitted light back, and is used interchangeably in the digital X-ray detector plate.

On the other hand, since the above-described fluorescent layer is formed on the digital X-ray detector plate, a high voltage problem applied to the X-ray receptor 200 to detect the electron hole pair formed in the X-ray receptor 200 by the X-ray. Is solved.

In detail, since the electron and hole pairs are generated in the X-ray receptor 200 layer such as a-Se by the visible light generated by the X-ray in the fluorescent module 500 or the fluorescent layer 510, the X-ray detection is performed. Since the thickness of the X-ray receptor 200 used for the purpose can be reduced, the magnitude of the applied voltage can be lowered.

As a result, an additional advantage in the manufacturing process that facilitates the vacuum deposition process of the X-ray receptor 200 is generated.

In addition, the high voltage of the both ends of the electrode was necessary to increase the detection efficiency when the number of electron and hole pairs generated in the X-ray receptor 200 is small. The voltage is enough to detect the signal.

As a result, the problem of destruction of the X-ray receptor layer and the TFT device due to the high voltage is solved. In particular, in the digital radiography apparatus, it is possible to shorten the life of the device or prevent device destruction caused by continuous high voltage application. .

EXAMPLE

Figure 3 is an X-ray photograph using an X-ray detector plate comprising a fluorescent module according to the present invention.

Fig. 3 shows that a clear image is obtained when the conventional X-ray detector plate without a fluorescent layer is applied with an undetectable X-ray, according to the present invention.

The X-ray irradiation conditions of this embodiment are 80 kVp, 2 mA and the X-ray generator used is Shimadazu TR-500-125.

According to the present invention described above, in order to detect the amount of electrical signal generated in the X-ray receptor layer, the applied voltage applied to both ends of the X-ray receptor can be kept low, so that the X-ray receptor layer in the manufacture of the digital radiation detection apparatus And an X-ray detector plate including a fluorescent module capable of protecting a TFT device.

In addition, X-rays comprising an fluorescence module that is particularly suitable for X-ray fluoroscopy apparatus and digital radiation detection imaging apparatus for mammography apparatuses that require continuous X-rays by showing excellent image acquisition rate with a small amount of X-rays There is an advantage that a detector plate is provided.

In addition, there is an advantage in that a digital X-ray detector plate in which a fluorescent layer is modulated to continuously maintain X-ray sensitivity is provided.

Claims (2)

The X-ray receptor layer and the X-ray receptor layer 200 formed on the upper and lower surfaces of the X-ray receptor 200 and the X-ray receptor 200 to generate electrons and hole pairs by X-rays X-ray detector plate for detecting the X-ray consisting of a lead-out device 100 for converting the electrical signal of the TFT substrate 100 layer and the X-ray receptor 200 layer as a physical support base into image information To A base 520 which is a physical support; A fluorescent layer 510 coated on the base and generating visible light by X-rays; The reflective layer 530 is formed on the fluorescent layer 510 to reflect visible light generated from the fluorescent layer 510. X-ray detector plate comprising a fluorescent module mounted on the X-ray detector plate in an exchangeable manner. The method of claim 1 wherein the fluorescent layer 510 is Calcium tungstate or rare earth-based fluorescent material or CsI (Tl), CsI (Na), NaI (Tl), ZnS, ZnS (Ag), ZnCdS, ZnCdS (Ag), Gd X-ray detector plate comprising a fluorescent module, characterized in that the material layer of any one of ₂ O ₂ S (Tb).