JPH07220673A - Ionization chamber x-ray detector and x-ray ct device - Google Patents

Abstract

PURPOSE:To provide an ionization chamber X-ray detector by which workability becomes excellent and highly accurate X-ray measurement becomes possible. CONSTITUTION:A signal electrode layer and a guard electrode layer are arranged on both surfaces of a five-layer structural electrode plate, and a height (a thickness) of an adhesive to fix electrodes is set not more than a height of a guard electrode. A signal take-out terminal 30 of a double side signal electrode plate 3 is arranged on the insulating plate 1 side to avoid an X-ray passage, and a contact area of a central metallic plate and the guard electrode layer insulated and separated from a signal conductor soldering area 301 is arranged on an end surface on the opposite side of an X-ray passing central part of this signal electrode take-out terminal. Thus contact area us formed in a connecting structure that the contact areas of the adjacent double side signal electrode plates 3 are connected to each other by solder through a metallic body 6 or are brought into pressure contact with each other by conductive rubber. Thereby, the characteristic deterioration is reduced, and highly accurate measurement becomes possible, and the noise by vibration of the terminal itself is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ionization box type X-ray detector, and more particularly to a signal extraction terminal connection structure suitable for an X-ray CT apparatus that requires a highly accurate X-ray detection capability and obtains a good image. The present invention relates to an ionization box type X-ray detector and an X-ray CT apparatus.

[0002]

2. Description of the Related Art A connection structure of signal extraction terminals of an ionization box type X-ray detector of a conventional X-ray CT apparatus is disclosed in Japanese Patent Publication No. 58-33509 and Japanese Patent Publication No. 58-166282. In the case of a three-layer structure double-sided signal electrode plate having metal layers on both sides of a single-layer structure signal electrode plate or insulating plate, a signal output terminal is provided at the end on the opposite side of the signal electrode plate in the X-ray incident direction. It is common to connect the signal to a printed circuit board or a connector terminal for extracting the signal to the outside of the X-ray detector through a lead wire or a flexible printed conductive pattern by soldering work at both ends. Alternatively, the signal output terminal and the conductive pattern of the printed circuit board are directly connected by soldering.

Further, as described in Japanese Utility Model Application Laid-Open No. 58-165689, in a double-sided signal electrode plate having a five-layer structure having a central metal plate such as molybdenum, insulating layers on both sides thereof, and metal layers on the upper surface thereof, Since it is necessary to perform a process of connecting the central metal plate to ground, and also a ground terminal for that purpose, these signal extraction terminals and ground terminals must be considered in consideration of the workability of connection with lead wires or flexible printed conductive patterns. Is provided at the end of the double-sided signal electrode plate on the opposite side to the X-ray incident direction, and further, the signal extraction terminal of the double-sided signal electrode plate and the high-voltage terminal of the high-voltage electrode plate are avoided as much as possible from the X-ray passage. The arrangement structure was close to the side of the insulating plate that fixed the plate.

FIG. 6 is a front view showing an example of the arrangement of signal extraction terminals and central metal plate terminals of a conventional X-ray detector. Figure 6
In detector case 10 filled with X-ray detection gas
X-rays enter through 0, and a plurality of double-sided signal electrode plates 3 having a five-layer structure are provided between the insulating plates 1 and 2 which are vertically arranged inside.
And the high voltage electrode plates 4 are alternately arranged, and the signal output terminal 30, the central metal plate grounding terminal 30A, and the high voltage terminal 40 are arranged on the side of the insulating plate 1 on the end surface on the side opposite to the X-ray incident direction of the electrode plates 3 and 4, and Although provided in the middle and on the side of the insulating plate 2, each of the terminals 30, 30A, 40 is in the X-ray passage.

Further, as an example of the guard electrode of the ionization chamber type detector, there is a description in JP-A-58-11592. This guard electrode structure is on a signal electrode plate consisting of a single metal plate, and is installed in a form where an insulating layer and a metal layer are attached to both ends on the side of the insulating base that fixes the signal electrode plate. Lead wires are connected to the electrodes by soldering and are grounded.

[0006]

In the above prior art, in the double-sided signal electrode plate of the X-ray detector having the five-layer structure, the signal take-out terminal and the central metal plate ground terminal are provided at the end portions of the signal electrode plate in the X-ray incident direction. However, the terminals are installed on the X-ray passage, and the solder swelling amount and the position of the terminals are varied due to the soldering work with the lead wires at each terminal. As a result of variation in the wiring position of the wire or the like, the electric field distribution near the connection is also delicately disturbed, and there is a problem that the accuracy of the X-ray measurement data decreases. Further, when the double-sided electrode is bonded to the insulating plate, the signal electrode area on both surfaces of the electrode plate may differ depending on how the adhesive is applied, which increases the detection error between channels.

Further, as a means for improving the above problems, the signal extraction terminal 30 of the double-sided signal electrode plate 3 and the high voltage terminal 40 of the high voltage electrode plate 4 should be avoided as much as possible from the X-ray passage as in the conventional example of FIG. In the case of adopting the arrangement structure that is moved to the side of the insulating plates 1 and 2, the center metal plate ground terminal 30A of the double-sided signal electrode plate 3 has enough room to be installed on the X-ray passage. If the arrangement is such that the signal extraction terminal 30 or the high voltage terminal 40 is moved to the side where the signal extraction terminal 30 or the high voltage terminal 40 is arranged, the distance between these terminals is narrowed this time, so that the wiring connection workability is extremely deteriorated and the ground terminal 3 is used.
In the wiring connection having a structure in which the arrangement of 0A is on the side of the high voltage terminal 40, there arises a problem that it becomes difficult to secure insulation between both terminals. In addition, when a guard electrode is added to the double-sided electrode as described in Japanese Patent Application No. 6-1269, a terminal for grounding this guard electrode layer is further added, which further deteriorates workability and improves accuracy in manufacturing. It becomes even more difficult in terms of terms.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to arrange the signal take-out terminal of the double-sided signal electrode plate having a five-layer structure, the guard electrode and the ground terminal of the metal plate itself on the X-ray passage. , High voltage terminals can be placed away from the X-ray passage, and the connection structure can also prevent the vibration of the signal output terminal to enable high-accuracy X-ray measurement and obtain an ionization box type with high-quality X-ray images. An object is to provide an X-ray detector and an X-ray CT device.

[0009]

In order to achieve the above object, an X-ray detector of the present invention comprises a case in which an X-ray detection gas is sealed, and insulating plates arranged in two rows in this case. ,
A plurality of double-sided signal electrode plates each having a five-layer structure in which a central metal plate, insulating layers on both sides thereof, and metal electrode layers on the central metal plates are laminated between the insulating plates It has a guard electrode layer that drops the leakage current to the ground, and a part of this double-sided signal electrode plate is projected so that the connection region between the signal electrode layer and the connection ground region between the guard electrode layer and the central metal plate are strip-shaped insulating layers. A signal extraction terminal formed separately, a high-voltage electrode plate alternately provided with the double-sided signal electrode plate between the insulating plates, a high-voltage terminal with a part of the high-voltage electrode plate protruding, and the metal electrode layer A signal extracting conductor connected to the connection region, a grounding conductor connecting to the ground region, and a connecting conductor connecting the high-voltage terminal to a high voltage source.

[0010]

In the above X-ray detector, the signal extraction terminal of the double-sided signal electrode plate having a five-layer structure causes a part of the double-sided signal electrode plate to project, and the connection region with the signal electrode layer of the five-layer structure and the guard electrode. The connection ground area between the layer and the central metal plate is separated by a band-shaped insulating layer, and is provided on the side of the insulating plate that can avoid the X-ray passage of this signal output terminal, and the center of the X-ray passage of this signal output terminal It is possible to provide a central metal plate ground region, which is insulated and separated from the end face on the side opposite to the part, from the connection region by soldering the signal extracting conductor to the metal electrode layer. In this way, when the grounding areas of the signal output terminals of the adjacent double-sided signal electrode plates are connected by soldering a metal plate as a connecting conductor or by pressure welding of a conductive rubber,
The signal extraction terminal has the soldering area of the signal extraction conductor and the grounding area of the central metal plate, so that there is no factor for disturbing the electric field in the X-ray passage, and the end surface of the double-sided signal electrode plate is maintained with the electrode accuracy and the guard electrode. As a result, the leakage current from the high-voltage electrode is passed to px, so that the deterioration of the X-ray detection characteristics is reduced and highly accurate measurement is possible. Furthermore, the longitudinal end face of the elongated signal output terminal is a metal plate. Alternatively, since a large number of adjacent terminals are connected with a connecting conductor such as a conductive rubber, the rigidity is improved and the terminal is strong against vibration, so that the generation of noise due to the vibration of the signal output terminal itself is reduced.

[0011]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 2 is a perspective view of an electrode block structure inside the detector showing an embodiment of the X-ray detector according to the present invention. Figure 2
Shows an electrode block arrangement structure in a case of an ionization box type X-ray detector for an X-ray CT apparatus, and there are insulating plates 1 and 2 made of a pair of ceramic materials arranged in parallel facing each other. A plurality of double-sided signal electrode plates 3 for extracting X-ray detection signals and a plurality of high-voltage electrode plates 4 commonly connected to a high voltage source are alternately arranged between the insulating plates in the X-ray generation source (X-ray focal position) direction. They are arranged substantially parallel to each other and fixed to the insulating plates 1 and 2 with an insulating adhesive, and in the case of this double-sided electrode type detector, the double-sided signal electrode plate 3 and the high-voltage electrode plate 4 which are adjacent to each other and X between them are arranged. The space of the line passage constitutes a one-channel detection element. An assembly of these insulating plates 1 and 2 and a plurality of channel detection elements is called a detection block, and a plurality of these detection blocks are arranged in parallel and a detector case in which xenon gas or the like (not shown) is enclosed. An X-ray detector is arranged inside. A signal output terminal 30 is provided so as to project above the end surface of the double-sided signal electrode plate 3 on the side opposite to the X-ray incidence direction, and a high-voltage terminal 40 is provided below the end portion of the high-voltage electrode plate 4 opposite to the X-ray incidence direction. Is provided.

3 (a) and 3 (b) are a side view and a front view, respectively, showing the structure of the double-sided signal electrode plate 3 according to the present invention shown in FIG. 3 (a) and 3 (b), FIG. 3 (a) shows a laminated structure of the double-sided signal electrode plate 3 in the electrode thickness direction as seen from the X-ray incident direction. There is a central metal plate 31 which is an X-ray opaque conductive material such as molybdenum, an insulating layer 32 such as polyimide is laminated on both surfaces thereof, and a signal electrode layer 33 such as a copper foil is provided on the outer side thereof.
And a guard electrode layer 34 are laminated, and a very thin adhesive layer is interposed between these layers, or they are firmly joined by heat fusion treatment such as high pressure / high temperature treatment to form one sheet. Of the double-sided signal electrode plate 3. The insulating layers 1 and 2 are fixed to the double-sided signal electrode plate 3 in the vertical direction with an insulating adhesive. Here, the thickness of the adhesive is set up to the middle of the guard electrode and adjusted to a height that does not reach the signal electrode layer (h <H). In this way, the insulating layer 32 completely insulates the central metal plate 31 and the signal electrode layers 33 on the two surfaces, and the signal electrode layers 33 on both surfaces are connected to the respective signal detection lines to connect to the respective channel detection circuits. This double-sided signal electrode plate 3 functions as a signal electrode element to be connected and is fixed on the insulating plates 1 and 2 with an adhesive having a high insulating property as shown in FIG. Because of the unstable state, the center metal plate 3 is actually
It is necessary to ground 1 and keep its potential at zero.

Next, FIG. 3B shows one shape of one side of the double-sided signal electrode plate 3. The left side of this rectangular parallelepiped electrode shape is the X-ray incident direction, and the vertical direction is the insulating plate 1. , 2 and the adhesive surface. For this reason, the signal output terminal 30 of the double-sided signal electrode plate 3 is located on the end face on the side opposite to the X-ray incident side (the back side as an X-ray detector) in order to secure the connection workability, and avoids the X-ray passage. In this example, the signal output terminal 30 is provided on the upper side of the end face close to the insulating plate 1 and the guard electrode layer 34 connected to the central metal plate 31 is grounded in addition to the signal output ports 301 of the metal electrode layers 33 on both sides. Area 3
02 are separated from each other by an insulating layer 32. Further, the pattern shape of each layer of the double-sided signal electrode plate 3 has the same shape in which the central metal plate 31 and the insulating layer 32 have the same size up to the end face, and the signal electrode layers 33 on both sides are separated from the end face by a predetermined constant distance. The center metal plate 31 has its own end face at the position.
The smaller shape ensures that the insulation is maintained.

FIGS. 4A and 4B are a partially enlarged view showing a detailed shape of the signal takeout terminal 30 of the double-sided signal electrode plate 3 of FIG. 4 (a) and 4 (b), FIG. 4 (a) shows the outer shape of the signal extraction terminal 30 of the double-sided signal electrode plate 3 which is the main part of the present invention, the shape of each layer pattern, and the etching pattern in the manufacturing process. , Fig. 4
(B) has the YY cross-sectional shape. The shape shown by the thick line in FIG. 4A shows the outer shape of the signal output terminal 30 of the double-sided signal electrode plate 3, and the metal electrode of the outermost metal foil layer is a strip shape along a part of the outer shape. Layer 33 is shown in FIG.
As shown in (b), the strip-shaped insulating layer 32 is exposed as shown by the dotted strips, and the metal electrode layer 3 at the tip of the terminal is removed.
The signal output port 30 is a connection region where the signal output line or the like is connected by soldering at a portion where the width of 3 is wide.
1, the signal electrode layer 33 in the area surrounded by the outer periphery of the outer shape of the terminal upper surface and the band-shaped insulating layer 32 and the central metal plate 31 on the outer periphery ground the central metal plate 31 to the ground potential. A ground region 302 is formed.

Here, the manufacturing process of the double-sided signal electrode plate 3 will be described with reference to the circumstances where the guard electrode layer 34 in the ground region 302 of the signal output terminal 30 of the double-sided signal electrode plate 3 and the central metal plate 31 on the outer periphery thereof are interconnected. Will be explained together. First, the five-layer structure of the double-sided signal electrode plate 3 of FIG. 3 (a) is created by applying the existing process for making an electronic circuit board. 31
It can be simply considered that the metal plate material such as molybdenum or the like and the insulating layer material of the insulating layers 32 on both surfaces thereof are used for the formation, and the shape of the metal electrode layer 33 of the double-sided signal electrode plate 3 of FIG. Is formed by performing the etching process of the current printed circuit board. Next, the outline process is as follows. (1) First, a five-layer structure material having a size larger than the size of the double-sided signal electrode plate 3 having a five-layer structure shown in FIG. 3A can be cut out, and (2) the double-sided signal electrode plate shown in FIG. 3B. 3 is an outer region of the outer shape of FIG. 3 and is only a portion of the metal conductor layer in the band-shaped region of the insulating layer 32 shown as a dot to be exposed of the signal extraction terminal 30 of FIG. Is used as an etching pattern P to perform etching treatment on both surfaces of the five-layer structure material to remove the metal foil of the metal conductor layer on the surface. (3) Finally, the double-sided signal electrode plate 3 shown by the thick line in FIG.
3B including the signal takeout terminal 30 of FIG. 3B, a press punching die matched to the entire outer shape of the double-sided signal electrode plate 3 is punched in accordance with the center line position of the etching pattern P in the strip-shaped region.

By doing so, as shown in FIGS. 4 and 3 (a),
As shown in (b), the metal conductor layer on the surface is punched out at a constant distance from the punched section except the guard electrode region and the ground region 302 of the central metal plate 31, so that the double-sided signal electrode plate 3 is punched out, so that the central metal plate is completely removed. Insulation between the signal conductor layers 33 on both surfaces sandwiching the insulating layer 32 is secured. Further, in the above process, the ground region 302 of the central metal plate 31 and the electrode end face of the guard electrode portion of FIG. 4 were not subjected to the etching treatment in the etching process of (2). When punching each layer with a press die, the ground region 302 and the metal electrode layer on the end face of the electrode plate of the guard electrode 34 are made of a material such as copper or aluminum which is very soft and has a large malleability and ductility. As shown in the figure, the cross-section distance of the insulating layer 32 is exceeded and the thin film is connected to the central metal plate 31 in a state like a very thin foil film.
Since the cross section of the center metal plate 31 is covered with copper foil and the cross section of the central metal plate 31 is copper-plated, this part has an advantage that soldering work of a ground wire or the like can be performed well. As described above, the signal take-out terminal 30 of the double-sided signal electrode plate 3 of FIG. 4 is the double-sided signal electrode plate which constitutes the one-channel detection element of FIG. The signal output port 301 forming a metal electrode layer connection region connected to the metal electrode layer 33 of No. 3 and the center metal plate ground region 302 connected to the center metal plate 31 and the guard electrode 34 of the double-sided signal electrode plate 3 are provided on both sides. It has a connection structure that is insulated and separated by a strip-shaped insulating layer 32 exposed at the bottom.

FIGS. 1 (a), 1 (b) and 1 (c) are front views showing an embodiment of the connection structure of the signal take-out line of the signal take-out terminal 30 of the double-sided signal electrode plate 3 of FIG. 4 and the grounding metal plate. FIG. 3 is a view of the A and B directions. 1A, 1B, and 1C, the signal output terminal 3 of the double-sided signal electrode plate 3 of FIG.
The signal extraction line 5 is connected to the signal extraction port 301 of 0 by the soldering process 50, and is connected to the central metal plate and the upper surface of the ground region 302 of the guard electrode layer.
1A and 1B, holes 60 which fit the small protrusions 303 on the upper surface of the ground area 302 are opened at equal intervals so as to match the intervals of the signal output terminals 30 of the adjacent double-sided signal electrode plates 3 as shown in FIG. 1B. If the hole 60 is inserted into the protrusion 303 and is connected and fixed by the soldering process 61, the signal extraction terminals 30 adjacent to each other are fixed to each other and are very strong against vibration. Has become. Further, the soldering processes 50 and 61 of the signal outlet 301, which is a connection region of the signal outlet line of the signal outlet terminal 30 of FIG. Since it is located almost above the lower surface, that portion hardly enters the X-ray passage, and the grounding metal plate 6 shown in FIGS. 1 (a) and 1 (c) is located above the lower surface of the insulating plate 1. However, since the X-ray passage is completely avoided, the connection structure is convenient for obtaining highly accurate X-ray measurement data. The shape and connection structure of the high-voltage terminal 40 of the high-voltage electrode plate 4 and the high-voltage metal plate 7 connected to the high-voltage terminal by soldering or the like as shown in FIG. 1C are the signal extraction terminals 30 of FIG. The external shape and the shape of the grounding metal plate 6 and the shape and soldering structure according to the soldering process 61 may be used, or an electric wire or the like may be used instead of the high voltage metal plate 7. Further, the metal plate 6 for grounding shown in FIG. 1A is not limited to this, and may be replaced with an electric wire or the like.

FIG. 5 is a front view showing another embodiment of the connection structure of the grounding metal plate of the signal output terminal 30 of the double-sided signal electrode plate 3 of FIG. In FIG. 5, the signal extraction terminal 30 of the double-sided signal electrode plate 3 is connected to the signal extraction port 301 by the soldering process 50, and the conductive rubber 8 is connected to the upper surface of the central metal plate ground area 302. Is pressed into the gap between the lower end surface of the insulating plate 1 and the cutout portion 10,
The fixing plate 11 provided on the end surface of the insulating plate is screwed with a fixing screw 12 to be held in the cutout portion 10 to form a connection structure. According to this embodiment, the soldering process is not necessary, and the elasticity of the conductive rubber material provides sufficient pressure contact connection, and the vibration of the double-sided signal electrode plate 3 is absorbed, so that highly accurate X-ray measurement data can be obtained. Can be obtained.

When the X-ray detector of this embodiment is used for an X-ray CT apparatus, it may be installed at a position facing the X-ray source with the subject in between.

[0020]

According to the present invention, the signal take-out terminal which is the connection region of the double-sided metal electrode layer and the central metal plate are connected to the signal take-out terminals of the double-sided signal electrode plate having the five-layer structure of the ionization box type X-ray detector. By providing a connection structure that is separated by a band-shaped insulating layer in the three regions with the ground region that is connected to the guard electrode layer, the leakage current from the high voltage electrode is absorbed by the guard electrode and flowed to the ground, and an adhesive, etc. As a result, the signal electrode layer is not connected, so that it is possible to form a highly accurate electrode layer.
Since there is no signal extraction port in the line passage, the accuracy of the X-ray detection element and the electric field distribution are good, and high-accuracy X-ray measurement is possible, and the ground area of the adjacent signal extraction terminals is soldered to the metal plate. Alternatively, by connecting the conductive rubber material by compression or the like, the rigidity of the signal take-out terminal can be improved, and vibration noise can also be improved.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a signal extraction terminal and a connection structure of an X-ray detector of the present invention, and A and B direction views thereof.

FIG. 2 is a perspective view showing an embodiment of the X-ray detector of the present invention.

3A and 3B are a side view and a front view of the double-sided signal electrode plate of FIG.

4 is a partially enlarged view of a signal output terminal of the double-sided signal electrode plate of FIG.

FIG. 5 is a front view showing another embodiment of the connection structure of the signal extraction terminals of the X-ray detector of the present invention.

FIG. 6 is a front view of an arrangement example of a signal extraction terminal and a central metal plate terminal of a conventional X-ray detector.

[Explanation of symbols]

 1 Insulation Plate 2 Insulation Plate 3 Double-sided Signal Electrode Plate 4 High Voltage Electrode Plate 5 Signal Extraction Line 6 Metal Plate for Grounding 7 Metal Plate for High Voltage 8 Conductive Rubber 10 Cutout 11 Fixing Plate 12 Fixing Screw 30 Signal Extraction Terminal 30A Central Metal Plate ground terminal 31 Center metal plate 32 Insulation plate 33 Signal electrode layer 34 Guard electrode layer 40 High voltage terminal 50 Soldering process 60 Hole 61 Soldering process 100 Case 301 Signal extraction port 302 Central metal plate ground region 303 Protrusion P Etching pattern

Claims (6)

[Claims] 1. A case in which an X-ray detection gas is sealed, an insulating plate arranged in two rows in the case, a central metal plate provided between the insulating plates, insulating layers on both sides thereof, and further above. A plurality of double-sided signal electrode plates each having a five-layer structure in which the metal electrode layers are laminated have a signal electrode layer and a guard electrode layer for dropping the leakage current from the high-voltage electrode plate to the ground. And a double-sided signal electrode plate between the insulating plate and a signal take-out terminal formed by separating a connecting region with the signal electrode layer and a connecting ground region between the guard electrode layer and the central metal plate with a strip-shaped insulating layer. And a high-voltage electrode plate alternately provided with the high-voltage electrode plate, a high-voltage terminal with a part of the high-voltage electrode plate protruding, a signal extracting conductor connected to the connection region of the metal electrode layer, and a grounding conductor connected to the ground region. Connect the body and the high voltage terminal to a high voltage source A connection for conductors, ionization chamber shape made of X
Line detector. 2. The ionization box type X-ray detector according to claim 1, wherein the strip-shaped insulating layer is formed as the strip-shaped insulating layer exposed by removing the metal electrode layer by etching or the like. 3. The ionization box type X-ray detector according to claim 1, wherein the signal output terminal and the high voltage terminal are provided in the vicinity of the insulating plate on the end faces of the double-sided signal electrode plate and the high voltage electrode plate opposite to the X-ray incident direction, respectively. vessel. 4. The ionization box type X-ray detector according to claim 1, wherein the grounding conductor is one of a grounding metal plate, an electric wire and a conductive rubber. 5. The ionization box type X according to claim 4, wherein a hole is provided in the grounding metal plate, a projection is provided in the connection grounding area, and the hole is inserted into the projection and connected by soldering or the like. Line detector. 6. An X-ray CT apparatus comprising the ionization box type X-ray detector according to any one of claims 1 to 5 provided at a position facing an X-ray source sandwiching a subject.