DE3644007A1 - IC detector system for computer tomographs and method and device for the manufacture thereof - Google Patents

Abstract

Gas detector systems for computer tomographs consists of individual detector cells which form a ring segment-like array, the detector cells being bounded by plates, which are aligned radially to the focus, between continuous side parts. For accurately aligning the plates, the carrying side parts have previously been correspondingly slotted. According to the invention, the side parts (11) are constructed to be smooth without slottings and are provided with a layer (12) of curable adhesive and the individual detector plates (14, 15) are fixed in location by the layer (12) of the adhesive. During the manufacturing process thereof, it is essential that the detector plates (14, 15) are first placed side by side by alternating nesting with wedges of appropriate geometry and are accurately aligned and then the plate/wedge packet is joined to the side parts (11). For this purpose, the associated manufacturing device essentially consists of a separate nesting station (31) for nesting the detector plates (14, 15) and a bonding station (32) for preparing the side parts (11), which is followed by a subsequent assembly station (33) for joining the detector plates (14, 15) to the side parts (11) and a welding station (34) for providing the voltage-conducting plates (15) with contacts. The stations (31-34) can be integrated into a flexible manufacturing cell. <IMAGE>

Description

The invention relates to an IC detector system for Computer tomographs according to the preamble of claim ches 1. In addition, the invention also relates to the Ver drive to manufacture such IC detector systems according to Preamble of claim 5 and an associated one Device according to the preamble of claim 13.

The heart of computer tomographs is the detector system for X-rays: This is usually on the part of the device opposite the radiation source and forms a so-called fan jet device Ring segment with, for example, 1100 individual elements. The Ab Educational characteristics of the computed tomograph depend significantly depends on the quality of the detector system.

So far, two different types have been used in fan jet devices Detector types used, namely gas detectors made of noble gas High pressure ionization chambers and semiconductor detectors Scintillation crystals made with photosensitive half conductors are combined.

Gas detector systems consist in particular of a Druckge inside the individual plate electrodes are brought. Xenon is preferably used as the gas filling a pressure of 10 to 20 bar. The chamber length in Beam direction is about 6 cm. The detector system comes with an operating voltage of 500 volts, for example. Semiconductor detector systems, on the other hand, are made up of individual detec  gate elements composed of encapsulated and on photosensitive diodes on cemented scintillation crystals about 5 mm thick. These individual elements are on mounted on a circuit board. A special operating voltage is not required.

With both systems it is for a sufficient picture quality mandatory that the individual detector elements, i.e. either the sheets or the semiconductor crystals are precisely aligned to the focal point of the system. This prepares in practice in the manufacture of such detec significant problems. According to the quality requirements must continue to be especially with the semiconductor detector systems a large number of semiconductor devices during of the manufacturing that the system is in its Influence costs significantly. In contrast there is a gas detector gate much cheaper. However, it depends specifically here the image quality is very different from the mechanical one Alignment of the individual sheets, what for the manufacture such systems must be mastered safely.

It is known from the prior art for the production of Gas detectors appropriately trained side parts in pre to split the sheet into these slots insert and by inserting a Kle bers to stabilize the position of the sheets. Doing so so dimension the slots of the side parts in their dimensions be sioned that the manufacturing tolerances of the slots as well as the sheet metal determine the slot width. As a result the orientation of the sheets becomes the focus of the system dependent on many eventualities.

In contrast, the object of the invention is an IC detector system for computed tomography to create tolerances are largely switched off in the position of the detector plates.  In addition, a method and the associated device be specified for the production of such detector systems.

The task is fiction, ge regarding the detector system according to the entirety of the features of claim 1 solved. A method of manufacturing such a detector systems is in claim 5 and the associated device specified in claim 13. Advantageous further training the detector system, the manufacturing process and the associated hearing device are in the related subclaims specify.

The invention is based on the consideration that the alignment focus and a constant chamber width at one Gas detector are the quality features, the pictures without Ensure distortion. The invention was based on the knowledge based on the fact that these points are already in the manufacture must be taken into account and the individual sheet spacings can be determined by wedges of the desired division. By alternating rows, i.e. Boxes of Wedges and sheets are provided with the appropriate box set-up all errors that occur during production compensable. This can be achieved in that Nesting device to match the individual chambers de wedges are defined and each sheet in its absolute Location and its orientation to the focus is measured for what two independent measuring systems on one measuring arm are located. This means that every sheet can be turned on immediately after bring to be examined for accuracy.

After the detector has been nested, a wedge can be used be placed, which holds the sheet / wedge package together. In the adhesive-coated screen becomes a gluing station tent parts defined pressed on the wedges and can in harden in this defined position. Then the  Wedges pulled and by contacting every other sheet to a 500 volt line the detector was completed.

It is essential in the detector system according to the invention that the side parts without slits and smooth are coated with a curable adhesive and that the one individual detector plates on the side due to the hardenable adhesive be fixed in a defined position. During the manufacturing process achieved by additional annealing that all glue stock parts are totally networked and a subsequent outgassing in Tomography device installed condition no longer occur can.

Further details and advantages of the invention emerge from the following figure description of execution examples. Each shows in a schematic representation:

Fig. 1 shows an IC-detector system in side elevation,

Fig. 2 shows a detector system according to the invention specifically in to Fig. 1 a vertical sectional direction, from which essential features of the invention will be apparent,

Fig. 3 is a flowchart for the manufacture of the detectors according to the invention,

Fig. 4 is an overall view of the stacking station,

Fig. 5 and 6 are two vertical sections through the chess Fig. Teleinrichtung the stacking station to the associated measurement means,

Fig. 7 shows the additional control device at the end of the measuring arm and

Fig. 8 is a sectional view of the assembly station.

In the figures, identical parts have the same reference characters and corresponding parts with analog reference numbers Chen provided. The figures are partly together wrote to in particular the specific manufacturing ver drive to explain for the detector systems.

In Fig. 1, a gas detector system 1 is shown, which can be used in a fan beam computed tomography device. The gas detector is approximately circular segment-shaped with a focus on F and physically realizes the principle of an ionization chamber (ionization chamber), for example 1100 individual units are present.

The IC detector system 1 consists in detail of a pressure vessel 2 , which is limited in the paper plane by (not recognizable in FIG. 1) side parts 3 and has a number of detector plates 4 and 5 . At every second detector plate there is a supply voltage of, for example, 500 volts from a voltage source 7 , so that a measuring cell is limited, the detector plates 4 lying in between serving as measuring probes. The measurement signals are each acquired via amplifiers 8 and fed to image signal processing units.

Essential characteristics of a good IC detector are an exact alignment of the sheets 4 , 5 to the focus F and a constant chamber width of the individual detector cells. In the prior art, the side parts are slotted in a predetermined division, the metal sheets are pushed into these slits and their position is stabilized by subsequently adding an adhesive. Since manufacturing tolerances of the sheets on the one hand and the slots on the other must be taken into account, an exact alignment of the sheets to the focus is not always guaranteed.

From Fig. 2 it can be seen that side parts 11 are provided with a layer 12 , in the detector plates 14 and 15 dip without touching the side parts 11 themselves. If a curable adhesive is used for the layer 12 , the sheets 14 , 15 can first be brought into a correct position with respect to the focal point F in such a construction. Subsequently be ßend which is provided with the adhesive layer 12 side parts 11, in which the adhesive has not yet cured, defined on the sheets pressed, so that each form in the layers 12 Einbettnuten 13 that do not go through to the side members. 11 By networking the adhesive in this position, the sheets 14 , 15 are fixed so that more of a detector system 10 with defined aligned individual sheets 14 and 15 is now created.

Epoxy resin, for example, which has highly viscous properties when processed, can be selected as the material for the adhesive layer 12 . The plastic is matched to the material of the side parts 11 , which consist, for example, of glass fiber reinforced epoxy resin (GRP). The detector plates are designed in a known manner and consist, for example, of molybdenum.

A detector system according to FIG. 2 can be produced in a defined manner: First, the individual sheets 14 , 15 are stacked on top of one another by alternating nesting with wedges of corresponding geometry (not recognizable from FIG. 2). The correct position of each individual sheet can be checked automatically when nesting. Is a pre-specified number of sheets and wedges strung together, the entire stack is fixed by an end wedge. In this fixed position, the sheets 14 , 15 are then glued to the side parts 11 and then the wedges are pulled out.

From Fig. 3, the schematic structure of a system for manufac turing of the detector system described with the associated process flow is shown schematically: It consists essentially of a nesting station 31 and an adhesive station 32 which are arranged an assembly station 33 and a welding station 34 . In the nesting station 31 , which will be described in more detail below with reference to FIGS. 4 to 7, the detector sheets 14 and 15 are lined up in succession, with the focus position being simulated. In parallel, the side parts 11 are prepared in the gluing station 32, the stacking sheets 14 , 15 and the side parts 11 being joined together in the assembly station 33 . In terms of procedure, who glued the sheets on the one hand and then welded the corresponding contact lines to the fixed sheets. Before the system is installed in a computer tomograph, the detector is additionally annealed. This ensures that all adhesive components are completely cross-linked and that subsequent outgassing cannot occur when installed.

In the described manufacturing process is essential that first the position of the detector plates 14, 15 is replicated "in situ" and that can be compensated for during the manufacturing steps tolerances in the plates 14, 15, in particular varying thicknesses and / or Winkligkeiten. This rules out the fact that tolerance deviations add up to larger errors and linearity errors can occur. Rather, it can be taken immediately upon detection of possible tolerance deviations that the deviations are compensated for and so that such errors do not arise at all. For this, the station 31 for stacking the sheets must be expanded in a specific manner.

In FIG. 4, the actual box 50, which is arranged in an oblique position at 15 ° deviation from the vertical and with reference to Figure 6. 5 and Fig. Is described in detail, 40 associated with a work platform with lifting platform to the reservoir 41, and 42 for the different detector sheets 14 and 15 on the one hand and a reservoir 43 for wedges of predetermined geometry on the other hand are arranged in a suitable manner. A grid I with columns I to III and rows a to f is formed in each case from the containers 41 and 42 , each of which can hold three or six stock parts classified according to different criteria. In example, three thicknesses and six angularities of the detector plates 14 and 15 are predetermined, so that a total of 18 different sheet types can result. With the aid of a computer with display 45 assigned to the box unit 50 , when stacking after measuring the focus position, it is indicated and the light-emitting diodes assigned to the fan matrix indicate which individual part is required for the next stacking process. This gives the operator precise instructions for the further manufacturing process. Likewise, an industrial robot or a handling system can be controlled accordingly in automated production.

From Fig. 5 and Fig. 6 it can be seen that the Schachtelein device 50 is designed such that the sheets 14 , 15 are measured with their interposed wedges in their absolute position by nesting in accordance with the distance between a measuring head located in the box. For this purpose, the box device consists essentially of a frame 51 with a bearing part 52 , a central part 53 and a box part 54 , with a pivot bearing 55 for a measuring arm 60 being present in the bearing part 51 . The pivot bearing 55 be consists of a bolt 56 in a holder 57 and an inner shaft 58 which engage in the measuring arm 60 . As a result, the measuring arm 60 can be pivoted about the pivot bearing 55 . The position of the swivel arm 60 can be changed and adjusted to a precise height position by means of a lifting device 65 in the front part 54 of the frame 51 . The lifting device consists essentially of a spindle 66 with associated linkage 67 and is activated by a motor 68 .

A first measuring system 70 is mounted on the measuring arm 60 at a distance from the box radius, with which the alignment of an individual sheet 14 or 15 to the focus F can be checked. The measuring system 70 is designed for example as an inductive Meßein direction.

At the end of the measuring arm 60 there is a second measuring system 75 for measuring the pitch for the simulation of the detector. The measuring system 75 is advantageously designed as an optical / electronic measuring device and has a so-called Exe 76 as measuring head, from which a measuring tape 77 is aimed.

Both measuring systems 70 and 75 supply electrical signals for evaluation in the computer and display on the display 45 . In addition, a visual control device 80 can be attached to the measuring arm 60, which will be discussed in more detail with reference to FIG. 7.

In the box part 54 of the frame 51 , a chess tel insert 100 for receiving detector sheets 14 and 15 and corresponding wedges can be inserted, which exactly reproduces the circular ring sector of the detector system to be manufactured with end parts 101 and 102 and a suitably designed sheet insert 103 . Bracket or adjustment means 104 to 106 are provided on the box part 53 for exact fixing.

From Fig. 5 of the measuring arm 60 is recognizable in an initial position bar. In the course of the nesting, the measuring arm 60 is gradually pivoted upwards via the lifting device 65 , with corresponding working positions being indicated by dashed lines. With the measuring arm 60 and the associated measuring devices 70 and 75 , each detector plate 15 or 16 can be checked for an exact position immediately after its introduction. Depending on the measured values, errors that occur during production can be compensated for immediately by selecting subsequent sheets with a correspondingly specified thickness and / or angularity due to tolerance deviations. In any case, the occurrence of summation errors is prevented.

While the measuring systems 70 and 75 work electronically according to FIG. 6, an immediate visual check of the nesting result is also possible by the operator. There is an additional control device 80 for : According to FIG. 7, this control device 80 consists essentially of a slide 81 which can be pushed on the measuring arm 60 , to which a measuring microscope 85 is attached via an angle piece 82 .

With the described box device, the detector plates 14 , 15 are now nested with a level of accuracy not previously achievable: after the finished nesting, an end wedge is placed so that the entire plate / wedge package is held together. The box set 100 can then be removed with the sheet / wedge package, the position of the sheets 14 and 15 not being changed.

In the separate adhesive station 32 , the side parts 11 are prepared in parallel and provided with an adhesive layer. For this purpose, appropriate dosing agents are available with which a layer of predetermined thickness can be applied to the side parts. In practice, so-called squeegees are used for this purpose, the layer thickness being checked continuously. The side parts 11 prepared in this way are then brought into the motor station 33 .

The assembly station 33 is shown in FIG. 8 has walls hand, consists essentially of a frame 90, the support means for the chess teleinsatz 100 on the one hand and for the side parts 11. It is important to design these holding means with adjustment devices in such a way that the box insert 100 with sheet / wedge package, which has been nested in the stacking device 50 , is not changed ver and that the side parts 11, in contrast, are relatively displaced independently of each other can. The Ge stell 90 consists in detail of two guided in columns 91 horizontal plates 92 and 93 , which are mutually height-adjustable and each carry a side part 11 in a defined position. In between, the box insert 100 with the sheet / wedge package is held by means of side slides 110 as a clamping unit.

For assembly, the upper plate 92 is first lowered onto the sheet / wedge package with a first side part 11 and pressed so far by means of a mechanical pressing device comprising a screw clamp 94 and a counterpressure plate 95 until the sheets 14 or 15 in the adhesive reach a defined immersion depth to have. The system waits until the parts are networked. Subsequently, a second coated side part 11 is inserted from the outside on the lower plate 93 into the correct position and raised to a defined height by means of a lifting device 96 , for example with a predetermined inclined plane, and pressed against the sheet metal / wedge package from below until the adhesive and the parts are cross-linked. It can be achieved in each case by a corresponding travel path that the detector plates 14 and 15 are immersed in the adhesive to a defined depth and do not touch the side parts 11 . There are each immersion grooves 13 in the layer 12 ge.

If the detector plates 14 and 15 are fixed and the adhesive is sufficiently cross-linked, the wedges in between are removed. The center flags of the 500 V sheets are then set and contacted with a continuous nickel strip. Finally, spacers made of GRP material are glued to the side parts to absorb the clamping forces of the position screws.

Before the final completion of the gas detector and on It will be placed in a gas-tight housing with gas filling Detector framework annealed again. This ensures ensures that all adhesive components are fully cross-linked are. An undesired subsequent outgassing of the Detek tion system is therefore excluded.

The described manufacturing device from stacking station 31 , gluing station 32 , assembly station 33 and welding station 34 forms a complete manufacturing cell with which detector systems of different geometry can be manufactured within the framework of flexible automation. The IC detector systems manufactured with this device are characterized by high accuracy. They have proven themselves in use with computer tomography, which work without complex semiconductor detectors.

Claims (25)

1. IC detector system for computer tomographs, which consists of a single detector cells that form a ring segment-like array, the detector cells are limited by radially out of focus sheets between continuous side parts, characterized in that the side parts ( 11 ) formed smooth without slits and are provided with a layer ( 12 ) of curable adhesive and that the individual detector plates ( 14 , 15 ) are fixed laterally through the layer ( 12 ) of the adhesive. 2. IC detector system according to claim 1, characterized in that the detector plates ( 14 , 15 ) are embedded in the end of the adhesive layer ( 12 ) and do not touch the side parts ( 11 ). 3. IC detector system according to claim 1, characterized in that the layer ( 12 ) of the curable adhesive made of epoxy resin, which has highly viscous properties when processed. 4. IC detector system according to claim 1, characterized in that the side parts ( 11 ) consist of glass fiber reinforced epoxy. 5. A method for producing an IC detector system according to claim 1 or one of claims 2 to 4, in which the detector sheets are fixed in a predetermined position radially to the focus system between two side parts, characterized by the following method steps:

• a) The sheets are lined up by alternating nesting with wedges of predetermined geometry,
• b) the correct position of each individual sheet is checked immediately during nesting and the next sheet defined is selected,
• c) the entire stack is fixed by at least one end wedge,
• d) in this fixed position, the sheets are glued to the sides,
• e) the wedges are then pulled out.

6. The method according to claim 5, characterized records that in process steps a) and b) Thickness and / or angularity of each sheet are taken into account, to compensate for summation or linearity errors. 7. The method according to claim 5, characterized records, in process step b) an additional downstream visual control with a microscope. 8. The method according to claim 5, characterized records that the side parts before gluing with highly viscous epoxy resin can be coated as an adhesive. 9. The method according to claim 5, characterized records that the reference potential leading sheets be contacted after gluing, whereas the measuring plates alternately with connecting pins above or below. 10. The method according to claim 5, characterized records that after step e) the detector system is annealed to complete networking pass.   11. The method according to claim 5, characterized records that in process steps d) and e) the entire nested sheet / wedge package in the assembly position held that first the upper side coated with glue Partly defined is pressed that after a given The next curing time is the lower one with adhesive layered side part is defined and that after The wedges expire after a further specified networking time to be pulled. 12. The method according to claim 5, characterized records that reusable wedges are used who those made of low-wear material in gauge block quality preferably made of steel. 13. Device for producing IC detector systems according to claim 1 or one of claims 2 to 4, using a method according to claim 5 or one of claims 7 to 12, characterized by a stacking station ( 31 ) for the sheets ( 14 , 15 ) and a separate adhesive station ( 32 ) for the side parts ( 11 ), a common assembly station ( 33 ) for connecting sheets ( 14 , 15 ) and side parts ( 11 ) and a welding station ( 34 ) for contacting the reference potential-carrying sheets connects. 14. The apparatus according to claim 13, characterized in that the stacking station has a chess teleinrichtung ( 50 ) for aligning the detector plates ( 14 , 15 ) in the radial direction to a predetermined point ( F ), which has a first measuring system ( 70 ) for checking the direction of each individual detector plate ( 14 , 15 ) to focus ( F ) and a second measuring system ( 75 ) for measuring the position of the detector plates ( 14 , 15 ) is assigned. 15. The apparatus according to claim 14, characterized in that the first and the second measuring system are attached to a common measuring arm ( 60 ) which is pivotable about a pivot bearing ( 55 ) as the focal point of the detector system ( 10 ). 16. The apparatus according to claim 15, characterized in that the first measuring system ( 70 ) for checking the sheet alignment on the measuring arm ( 60 ) was in the Ab of the box radius. 17. The apparatus according to claim 13, characterized in that the second measuring system ( 75 ) for measuring the absolute position of each individual detector plate ( 14 , 15 ) is located at the end of the measuring arm ( 60 ). 18. The apparatus according to claim 15, characterized in that on the measuring arm ( 60 ) in addition, a microscope ( 80 ) on a carriage ( 81 ) can be slidably arranged as a visual control system. 19. The apparatus according to claim 15, characterized in that the pivoting about the pivot bearing ( 55 ) measuring arm ( 60 ) by means of a spindle drive ( 66 , 67 ) with an associated motor ( 68 ) is displaceable. 20. The apparatus according to claim 13, characterized in that the box device ( 50 ) of the stacking station ( 31 ) has adjustment means for reproducibly inserting a box insert ( 100 ). 21. The apparatus according to claim 20, characterized in that the box device ( 50 ) storage devices for detector plates ( 14 , 15 ) on the one hand and wedges on the other hand are assigned, in particular the detector plates ( 14 , 15 ), classified according to thickness and / or angularity, can be removed under computer control. 22. The apparatus according to claim 13, characterized in that the adhesive station ( 32 ) has adjustment means for the side parts ( 11 ). 23. The device according to claim 22, characterized in that the adhesive station ( 32 ) Dosie approximately for the uniform application of an adhesive layer of predetermined thickness. 24. The device according to claim 13, characterized in that the assembly station ( 33 ) consists of a frame ( 90 ), the holding means ( 91-94 ) for side parts ( 11 ) on the one hand and the box insert ( 100 ) on the other. 25. The device according to claim 22, characterized in that in the frame ( 90 ) adjusting means for the relative displacement of the side parts ( 11 ) and box insert ( 100 ) are available.