JPS60234645A - Dental radioactive image supply apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a dental radiographic image providing device, and more particularly to a device for providing a dental radiographic image on a monitor of a display system.

BACKGROUND OF THE INVENTION Major advances in electronic technology over the past few years have resulted in considerable improvements in radiological diagnostic techniques for the human body. While these improvements improve radiographic images,
X-ray exposure to patients and operating personnel is decreasing.

However, traditional radiography is still used in dental diagnostic techniques.

That is, conventionally, the tooth to be examined is located between an extraoral X-ray source and an intraoral radiation film that is sensitive to the X-rays passing through the irradiated tooth. The shape of the image appearing on this film corresponds to the shadow formed by the more or less opaque components to X-rays of the tooth width being examined. Although such dental radiography techniques are currently in common use, their main drawback is that the number of exposures is limited due to the required X-ray dose.

New radiological technologies are particularly directed towards the basic design of sensors for sensing the x-ray beam emanating from the irradiated target, in order to improve the quality of radiographic images while reducing the x-ray exposure time. It's here. In addition, since images can be obtained immediately with such a device, the film development step required for conventional dental radiography can be omitted.

However, since the maximum size of the X-ray beam sensor is limited so that it can be easily introduced into the oral cavity, it is extremely difficult to apply such a device to the field of dental radiology. Therefore, a major problem with such devices, especially those of the type that can be provided on the monitor of a dental radiology image display system, is to provide a sensor for sensing the x-ray beam emanating from the irradiated tooth. The aim is to make it as thin as possible so that it can be placed behind any tooth under examination in the oral cavity.

The design of such a device has already been published in U.S. Pat. No. 4.160,
No. 997 (Schwartz), in which a sensor consisting of a charge-coupled device (CCD) and a screen located in front of the CCD is provided, the X-rays generated by the irradiated tooth being absorbed by the screen. It can be converted into a light beam with a wavelength r suitable for COD. , C.C.
D has its maximum output in the visible spectrum, and on the screen is provided a scintillator material that converts Xa into visible light. The small size of the CCD meets the requirements for a compact intraoral sensor that can significantly reduce the amount of x-ray exposure while providing images of excellent quality. The features of CCDs and their technical advantages will be obvious to those skilled in the art and will not be described herein.

The main drawback of the intraoral sensor described in the said US patent is that its essential function is that the X-ray beam generated from the irradiated tooth is recorded and the output data is provided for analysis by an electronic processing unit. However, the function 4 of displaying this tooth image on the monitor of the display system cannot be fulfilled.

To understand why this intraoral sensor is not functional, it is useful to recall that the COD has the following properties: its sensitive surface is too small. Therefore, it is not possible to completely collect the X-ray beam generated from the irradiated tooth, and therefore, in the above-mentioned US patent, the intraoral sensor has a linear transmission (Iinea, r tran).
It has been proposed to provide a screen that allows the s-mission.

Also, the surface of the CCU has an energy r higher than 1 keV.
However, the screen cannot adequately protect this surface.

Furthermore, the maximum permissible distance between this COD and the electronic unit for processing the electrical output information t data supplied from the COD, i.e. the longest distance at which an output signal of processable strength can be obtained, is the finch (approximately 20cm
), however, the electronic unit for data processing of the output information in the intraoral sensor of the US patent is located outside the oral cavity and is connected to the sensor by a cable as long as the finch.

(Problems to be Solved by the Invention) It is an object of the present invention to provide a device capable of providing a dental radiographic image on a monitor of a display system without causing the above-mentioned drawbacks. It is something.

In particular, it is an object of the present invention to provide a functional device capable of reproducing images of teeth in high quality and significantly reducing the amount of X-ray irradiation.

(Means for Solving the Problems) The device according to the invention comprises an extra-oral X-ray source and an X-ray beam passing through the irradiated tooth, which is coaxial with respect to the comprising an intraoral sensor for sensing and an extraoral electronic data processing unit connected to said sensor, said sensor comprising a COD and a screen located between the COD and the irradiated tooth. At the entrance of the tube, there is provided a ntillator that converts the X-rays that have passed through the teeth into visible light.

Also according to the present invention, (1) various elements of the optical system combined for the transmission of the tooth image, namely the scintillator, the screen, and the C.
The diameter of the main part of the CD is gradually increased as the tooth image is transmitted in order to optimize the resolution of the pixels in the CCD, and as a result, the "moiré" effect is reduced. (ii) The front screen is made of stabilized glass mixed with metal oxide particles for the purpose of absorbing the X-ray energy not converted by the scinter.
Reduced optical fiber (r
(iii) the intraoral sensor 1ccD (z monitoring,
and microelectronic means (m) for amplifying the output signal sound.
icroelectronic means) 2.

(Operations and Effects of the Invention) The intraoral sensor of the present invention as described above is not an obviously inoperable sensor consisting of a combination of a scintillator, a screen, and a CCD, but a newly designed and combined three configurations. The elements form an optical system particularly suitable for the field of dental radiology.

Namely, as the diameters of the main parts of the various elements of the optical system gradually increase with the transmission of the tooth image, the overlap between the "emitting" and "receiving" parts increases the "moiré" effect. It can be effectively prevented. The "moiré" effect can be reduced by overlapping the matrix pattern formed over the optical fibers on the screen exit so as to intersect the matrix pattern of the COD at an angle of '745°. This value of 45° means that if the lines of both matrix patterns overlap, a double "moiré" will occur.
They were chosen because they intersect at an angle of 90°, causing the effect r. Therefore, it is desirable that the number of scintillator crystals facing the optical fibers on the entrance of the screen be large enough to balance the number of optical fibers coming out of the screen facing each pixel on the sensitive surface of the CCD. This balance is suitable for scintillators with a diameter of 3 to 4μ.
using a crystal r, the diameter of the optical fiber on the entrance of the screen is 7
9-14μ, the diameter k of the optical fiber on the exit of the screen is 4.5-7μ, and the diameter of the pixel for CCD is 23-34μ.

Additionally, by using a reduced optical fiber tray screen between the inlet and outlet with a reductive rate of approximately 2, (1) the number of optical fibers facing each pixel in the ccD is increased; ii) The dimensions of the sensitive surface of the COD match the dimensions of the screen entrance (this is imposed by the dimensions of the Xa beam originating from the irradiated tooth and corresponding to its dimensions), and the intensity of light 7 The amount of X-rays irradiated is four times that of the surface, and therefore the amount of X-ray irradiation is one fourth.

Optical fibers preferably have a low darkening coefficient for complete visible light transmission.
In addition, 50% of the silicon that forms the optical fiber is mixed with metal oxide particles with a large atomic weight to form a scintillator.
It is advantageous to be able to absorb the X-ray energy that has not been converted by. The metal oxide particles protect the CCDt by blocking the path 4 of the X-rays rejected by the COD. According to a more preferred embodiment of the present invention, the metal oxide particles have a tetravalent chemical structure,
Since its melting point is higher than 1500 DEG C., it is possible to spin the reduced optical fiber containing the particles to a diameter of 4.5 to 7 microns, which corresponds to the diameter of the optical fiber at the exit of the screen.

Furthermore, the intraoral sensor according to the invention is provided with microelectronic means for monitoring the triCCD and increasing its output signal. This microelectronic means eliminates the problem of transmitting electrical data from a CCD larger than a finch (approximately 20 crrL). For this purpose,
Amplification of the data is performed to enable transmission of electrical signals to an electronic data processing unit of the display system. However, when this electronic means is installed in the intraoral sensor, the volume of the CCD increases, and the temperature of its constituent components increases, generating heat around the device, resulting in an increase in the noise of the device. happen. In order to overcome this difficulty due to the size of the electronic means, in a particularly preferred embodiment of the invention (i) the chip constituting the functional part of the CCD is drawn out, and (11) its sensitivity to visible light is The surface is fixed onto the optical fiber on the screen exit, and on the other surface on the ceramic substrate the microelectronic means are provided by multilayer technology for their miniaturization.

Therefore, it can be said that the volume occupied by the various components of the optical system along the image transmission direction is reduced to its minimum value. Miniaturization only affects the thickness of the CCD.

This is because (1) the total thickness of the intraoral sensor must be approximately 17 or less in order to be easily introduced into the oral cavity;
1) Optical diffusion problem? The thickness of the scintillator must be less than 100μ in order to prevent a sufficient reduction (rate: 2) between the irradiated tooth surface and the tip surface to obtain a suitable τ. This is because the screen thickness must adhere to a limited minimum dimension.

To prevent overheating of the microelectronic means, temperature-prone components (ie voltage compatible components) are separated and placed on transverse projections perpendicular to the ceramic substrate. This results in the main advantage of isolating the chip from heat generating components and reducing noise. Particularly preferred embodiments of the present invention further limit the temperature rise 7 in the exothermic electronic component, wherein the power source of the microelectronic means for monitoring and amplifying the output signal and the power source of the x-ray source are connected to the display system. A single image is obtained on the monitor and is kept synchronized for the required time for diagnosis. The possible time limit for this power supply has been experimentally measured to be several hundredths of a second, and has the double advantage of considerably limiting the amount of X-ray irradiation and the temperature rise t in the exothermic electron component. As a result, miniaturization of this sensor is achieved by inserting microelectronic means into the intraoral sensor.

According to a further preferred embodiment of the invention, the scintillator is coated onto the optical fibers above the screen inlet by depositing a layer of particles with a constant particle size of 3-4 microns. The total thickness of the deposited layer is less than 100 μm to prevent optical diffusion inside the non-tilator. The emission wavelength of these crystals is between 500 and 800
nm T: Yes, corresponding to the optimal reaction area of a pixel on the chip. It was thought that the enticillator having such a configuration would improve the quality of reproduced images.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

The device shown in the drawing includes, for example, an external X-ray generator for irradiating the teeth 2 of the lower jaw, an intraoral sensor 3 provided behind the teeth to detect the X-rays that have passed through the teeth 2μ, and an intraoral sensor. An extra-oral wire (not shown) connected to the sensor 3 by a cable 4a records the electrical information output from the sensor 3 and then displays the image of the tooth 2 on a monitor (not shown) of a display system. Consists of an electronic data processing unit.

The intraoral sensor 3 records a complete image of the tooth 2 exposed to the irradiation 4 while being sufficiently small to be easily placed behind the tooth in the oral cavity. Note that the sensor is illustrated on a scale of about 5 times so that the EA of the present invention can be better understood.

The coating material of the sensor 3 has approximate dimensions of 30 mm (h) in height, 20 mm (1) in width, and 17 m in thickness.
It is formed into a rectangular parallelepiped with +u(e), so that it can completely record the X-ray beam generated from the teeth and can be easily introduced into the mouth.

The intraoral sensor 3 has a CCD chip 4, which is fixed to one face 5a of a truncated plane of a screen 5, which has a truncated pyramid shape and whose base 5
b is coated with a scintillator 6, and this scintillator is exposed to the X-rays generated from the tooth 2 that has been exposed to radiation 4. Converts to visible light. This visible light l-j: 500 to 8, especially at the base 5b, which corresponds to the optimum reaction zone of the chip 4.
The chip 4 records better when coated with a crystal having a wavelength in the range of 0.00 nm.

The dimensions of the base 5b of the screen are X generated from the teeth 2
The dimensions of the truncated plane 5a must be such that they provide a surface that can be completely accommodated, and the dimensions of the truncated plane 5a provide a surface that is small enough to be covered by the chip 4. You have to throw it with something you can do.

The screen 5 is made of a reduced optical fiber (reduction ratio of about 2) formed using stabilized glass γ mixed with metal oxide particles.

In addition to reducing the tooth image between the entrance or face 5a and the exit or base 5b of the screen,
The optical fiber transmits tooth images one by one between the scintillator 6 and the chip 4, and is due to the fiber's shrinking ability which increases the light intensity σ at a rate proportional to the square of the fiber's shrinkage ratio. This makes it possible to reduce the amount of X-ray irradiation.

The metal oxide particles mixed into the optical fiber are 5% smaller than silicon.
By making it have a 0% larger atomic weight r, it is possible to absorb most of the X-rays that cannot be converted by the scintillator 6, thereby ensuring a reliable protection function for the chip 4. Furthermore, the chemical structure of the selected metal oxide should have a tetravalent outer shell 4, and its melting point should be higher than 1500°C to obtain chemical and physical compatibility with silicon, and optical Fiber τ4.5~7
This is necessary in order to obtain a viscosity that allows spinning with a diameter of μ. - That is, when the X-rays passing through the two teeth collide with the crystal of the scintillator 6, they emit visible spectrum light 7 representing an image of the tooth 2, and this image is transmitted to the screen 5 by the optical fibers.
The light is guided point by point to the entrance of the chip 4 while being reduced in size. According to the invention, this chip is extracted from its casing and placed on a thin ceramic substrate 7, which is fixed to the side of the chip opposite to the side facing the screen 5. In addition, this substrate has microelectronic means 87 for monitoring the chip 4r and amplifying its output signal and transmitting the electronic signal t to the end of the flexible cable 4a, where it is processed by the electronic unit of the display 7 stem. are doing.

electronic components that tend to generate heat, i.e. the components ensuing
The microelectronic means 8a is separated from the microelectronic means 8 and placed on a lateral protruding member 7a perpendicular to the ceramic substrate 7, so that heat generation around the chip 4 due to temperature rise of these components is prevented. Prevented.

According to a preferred embodiment of the invention, a truncated pyramid (
A lead belt 9 having a plane τ parallel to the base 5b of the truncated pyramid screen 50 is provided on the side surface of this truncated pyramid. This lead belt 9 is located on a high stone two-thirds of the total height of the pyramid from the base 5b. The components located above this lead belt 9 (i.e. the chip 4 and the microelectronic means 8t)
The screen 5 located in front of the belt 9 protects the X-rays not converted by the scintillator 6 from those having a linear passage r penetrating in the thickness direction. (2/3 of the total thickness, i.e., 2/3 of the total height of the truncated pyramid) was determined experimentally as the minimum thickness necessary to allow sufficient X-ray absorption. It is something that

The aforementioned components (chip 4, screen 5, scintillator
6. All external surfaces of the ceramic substrate 7, the microelectronic means 8 and the lead belt 9) are preferably embedded in a coating material IO, preferably a black polyurethane resin.

That is, by doing this, (1) it becomes possible to selectively pass specific wavelengths, preventing the passage of visible light from the outside, while allowing them to pass through the X-ray t-sensor 3, and allowing them to pass through the scintillator 6. (11) It is possible to obtain a low thermal conductivity that limits the heating of the electronic components around the chip 4, (110 to achieve electrical insulation) +IV) It becomes possible to mechanically protect the sensor from impact.

According to a further preferred embodiment of the invention, the sensor 3 is housed in a disposable sterile pack (not shown) that is biocompatible with the oral cavity.

In order to place the sensor 3 in a position suitable for receiving the X-ray beam emanating from the irradiated teeth in the mouth, this sensor is arranged such that one end of the sensor can be freely placed between two opposing teeth. It is movably and connectably connected to the other end of one arm.

[Brief explanation of drawings] The drawing is a sectional view schematically showing the apparatus of the present invention.

Claims (1)

[Scope of Claims] (1) An external X-ray source and an intraoral sensor disposed coaxially with the X-ray beam generated from the irradiated tooth so as to sense the X-rays passing through the irradiated tooth. , an external data processing unit connected to the sensor, comprising the sensor 1ccD and a screen;
This screen is located between the CCD and the tooth that receives the radiation, and a scintillator is provided at the entrance of the screen to convert the X-rays that have passed through the tooth into visible light. formed of a layer of a translucent material that allows light to pass through, the translucent material being mixed with particles that prevent the passage of X-rays not converted by the scintillator passing through the scintillator; screen, and the CO
Each main part of the various components of the optical system consisting of D is CC
the screen was not diverted by the scintillator, and the screen had a diameter r that gradually increased with the transmission of the tooth image so that the resolution of the pixels in D was optimal and the double moiré effect was reduced; The intraoral sensor has a reduced optical fiber mixed with a metal oxide that absorbs X-ray energy, and the intraoral sensor is the CCD? ! 1. A device for providing a radiological image of a tooth on a monitor of a display system, characterized in that it comprises microelectronic means for monitoring and amplifying the output signal of the CCD. (2) The matrix pattern formed by the optical fibers on the screen exit is overlapped with the COD matrix pattern so as to intersect at an angle of 45°. Device. (3) The scintillator crystal has a diameter of 3 to 4μ, the reduction optical fiber has a diameter of 9 to 14μ at the entrance of the screen and 4.5 to 7μ at the exit, and the diameter of the pixel of the CCD. is 23 to 34μ
An apparatus according to claim 1, characterized in: 4. The apparatus of claim 1, wherein the optical fibers of the screen are made of stabilized glass having a low darkening coefficient. (5) said COD has a chip constituting its functional partials, said chip being withdrawn from its casing, its sensitive surface being fixed and bulging on the optical fiber on said screen exit, and its opposite surface being attached to a ceramic substrate; I feel like I'm stuck with it,
2. Device according to claim 1, characterized in that said microelectronic means are arranged by multilayer technology and are supported by said ceramic substrate. (6) The scintillator is coated on the inlet of the screen to deposit crystals with a constant particle size of 3 to 4μ, and the deposited layer has a total thickness of less than 100μ to prevent optical diffusion phenomena. 2. A device according to claim 1, characterized in that it has an emission wavelength in the range of 500 to 800 nm, which corresponds to the optimum reaction range of COD. (7) A stabilized glass from which the optical fibers are spun, such that metal oxide particles mixed into the optical fibers of the screen enhance the dust absorption of the screen for X-rays not converted into visible light by the printer. The metal oxide particles also have a tetravalent chemical structure and a structure that allows shrink optical fibers containing the particles to be spun to diameters of several microns. Device according to claim 1, characterized in that it has a melting point higher than 1500°C. (8) The power supply of said microelectronic means causes said
6. A device according to claim 5, characterized in that it is adapted to be synchronized with a radiation source. (9) the screen formed by the reduction optical fiber has a truncated pyramid shape with an upper surface 7 parallel to the base, and the scintillator is located at the base of the pyramid;
The sensitive surface of the chip is fixed to the truncated top surface of the pyramid, and a lead belt having a surface parallel to the base of the truncated pyramid extends from the base to a height of 2/3 of the total height of the pyramid. 8. A device according to claim 7, characterized in that it is located and projects from a side of said pyramid. (lO) of the constituent components of said microelectronic means, those that tend to increase the temperature around the chip are separated;
9. The device of claim 8, wherein the device is provided on a laterally projecting member of the ceramic substrate, the projecting member being perpendicular to the remaining components affixed to the chip. (11) The outer surface of the component of the intraoral sensor is (1)
(ii) to prevent the passage of external visible light so as not to disturb the reception of X-rays by the scintillator, while allowing the sound of X-rays to pass; and (ii) to limit heat generation of electronic components located around the chip. Obtaining low thermal conductivity, (ii
11. Device according to claim 10, characterized in that: i) the sensor is embedded in a coating material so as to achieve electrical insulation and mechanically protect the sensor from impact. (12) The dimensions of the intraoral sensor are such that it can be easily inserted into and withdrawn from the mouth, and the dimensions of the screen base are such that the size of the screen base is such that it can be easily inserted into the mouth and easily withdrawn from the mouth; a complete image r is received at the inlet of the screen such that the dimensions of the truncated surface of the pyramidal screen affixed to the sensitive surface of the chip of the COD are sufficient to be recorded by the sensitive surface of this chip. The image of the tooth having a size reduced to a certain degree is supplied onto the exit of the screen, and the height of the pyramid-shaped screen corresponds to the length of the optical fiber mixed with metal oxide particles τ, and the height of the pyramid-shaped screen corresponds to the length of the optical fiber mixed with metal oxide particles τ, and The energy of the X-rays not converted into visible light by the scintillator so as to protect the sensitive surface? (13) The device according to claim 1.1, characterized in that the coating material is a black polyurethane resin. The device according to scope 11. (14) The entrance of the intraoral sensor corresponding to the base of the truncated pyramid is rectangular in size 3C1mm x 2Q, and the scintillator, screen, chip, microelectronic means and coating material The device according to claim 12, characterized in that the thickness of the intraoral sensor corresponding to the total thickness of is less than or equal to 17 cm. (15) The intraoral sensor is movable and connectable. The device according to claim 1, characterized in that the intraoral sensor is arranged in the oral cavity by an arm. (16) The intraoral sensor is housed in a disposable sterile pack. The device according to claim 1, characterized in that