JP2007047173A - Detector module, detector and computerized tomographic scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure a sufficient space for arranging an electronic circuit for signal processing at the vicinity of a detector. <P>SOLUTION: The detector module is provided with the detector array and the first printed circuit board (12), which keeps the detector element array arranged on the one side of the circuit board (12); at least one recess (15) provided in the first printed circuit board (12); and at least one electronic device (16) for signal processing arranged in the recess (15). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a detector module having an array of detector elements and a printed circuit board. Furthermore, the invention relates to a detector and a computed tomography apparatus having such a detector module.

  In an imaging method using an X-ray apparatus having an X-ray source and an X-ray detector, for example, a computed tomography apparatus, the entire organ such as the patient's heart is scanned by one rotation of the X-ray system around the patient, for example. In order to be able to do so, efforts are made to make the detector surface of the X-ray detector that can be used for image acquisition as large as possible. This type of X-ray detector, called a planar detector, is generally composed of a number of detector modules arranged in two dimensions. Each detector module has, for example, a scintillator array and a photodiode array that are aligned with each other and form the detector element of the detector module. The scintillator elements of the scintillator array convert incident X-rays into visible light, and the visible light is converted into electrical signals by the photodiodes in the photodiode array.

  It has been found that the problem during assembly of the planar detector is the electrical connection of the photodiodes of the detector module. In an X-ray detector assembled with individual detector modules arranged one behind the other and arranged on an arc, the signal processing electronics can be placed laterally or the electrical of the photodiode of the module The cable used for the connection can be extended laterally with respect to the printed circuit board having the signal processing electronics (see, for example, US Pat. It is. This is because there is no free space on the side due to the two-dimensional arrangement of detector modules. In this case, the electronic circuit device for processing the measurement signal supplied from the detection element of the detector module should be placed as close as possible to the detection element for measurement technical reasons. An area occupied 2-4 times larger than the detection surface is required. For this reason, it seems necessary to configure the detector module with the signal processing electronics in the vertical direction.

  A structure of a planar detector in which a large number of detector modules each including so-called element modules are arranged is known (for example, see Patent Document 2). The element module of the detector has a vertical structure, that is, the elements of the element module including a scintillator, a photodiode, a substrate having a signal processing electronic circuit device, and a module base plate are vertically superposed.

In the case of this type of vertical structure of the detector module, better heat dissipation must be considered. Otherwise, considerable heat generation during operation of the signal processing electronic circuit device may cause damage to the electronic circuit device.
US Patent Application Publication No. 2002/0029463 US Pat. No. 6,396,898

  The object of the present invention is to make it possible to assemble the detector module described at the beginning so that a planar detector can be assembled and that there is sufficient space for the placement of the signal processing electronics near the detector surface. There is to configure. It is another object of the present invention to provide a detector assembled from this type of detector module and a computed tomography apparatus having such a detector.

  In accordance with the present invention, a problem with a detector module includes an array of detector elements and a first printed circuit board, the array of detector elements being disposed on one side of the first printed circuit board, This is solved by the fact that the circuit board has at least one recess, and at least one electronic device used for signal processing is disposed in the recess. A vertical structure of the detector module is therefore proposed. Providing the concave portion in the first printed circuit board is equivalent to configuring the printed circuit board in a frame-like structure, and the assumption is made that an electronic device for signal processing is disposed in the concave portion to be protected. Since the array of detection elements and the first printed circuit board are generally flush with the outside, two-dimensional parallel arrangement is possible on all sides.

  According to this embodiment of the first printed circuit board, a second printed circuit board is arranged under the first printed circuit board as a continuation of the vertical structure of the detector module, according to a variant according to the invention. Can do. The second printed circuit board similarly has at least one recess, in which at least one electronic device for signal processing is arranged. By arranging the signal processing electronic device in the recess of the printed circuit board, a plurality of such printed circuit boards can be arranged one above the other depending on the occupied space required for the signal processing electronic device. With this embodiment of the printed circuit board, a compact and stable structure of the detector module is achieved, and sufficient space can be used to place the signal processing electronics near the detection element.

  According to a variant of the invention, the recess is preferably formed in the shape of a cuboid or a slit, the latter being made by simple milling.

  According to an embodiment of the present invention, the first and second printed circuit boards are connected to each other such that an electrical signal can be transmitted from one printed circuit board to the other printed circuit board. According to a variant of the invention, the electrical connection between the two printed circuit boards is effected by means of a frame-like plug, so that electrical signals can be transmitted between the two printed circuit boards without additional connection cables. it can. This allows a compact structure of the detector module with a clear outer shape, so that a plurality of detector modules of this kind can be easily arranged in parallel in a planar shape. With respect to the transmission of electrical signals between printed circuit boards, this transmission is not only the transmission of signals measured by the array of sensing elements, but also the supply current or supply voltage and possibly on the printed circuit board. It also means the transmission of control signals for the electronic device.

  According to a variant of the invention, at least one ASIC (Application Specific Integrated Circuit) does not protrude from the recess in the recess of the first printed circuit board and / or in the recess of the second printed circuit board. Thus, the printed circuit board can be placed on the same plane. Furthermore, other electronic devices arranged in the recesses are also arranged so as not to protrude from the respective recesses.

  Preferably, the ASIC disposed in the recess of one printed circuit board is substantially flush with the surface of the printed circuit board. According to a modification of the present invention, an interposer having a thermally conductive material is disposed between the first printed circuit board and the second printed circuit board, so that the ASIC is brought into contact with the interposer, Since the ASIC can be disposed on the interposer plate, the heat generated during the operation of the detector module or ASIC can be discharged through the interposer plate. According to an embodiment of the invention, the interposer plate is made of metal, for example copper or aluminum.

  According to another variant of the invention, the detector module is arranged on a carrier plate which likewise has a thermally conductive material. The carrier plate may be coated with a thermally conductive material such as copper, but it can also be made entirely of this kind of material. In order to allow the heat generated during operation of the detector module to be well discharged from the detector module via the carrier plate, according to an embodiment of the present invention, the detector module has a suitable thermal conductivity connection. It is fixed to the carrier plate by means. As a suitable connection means for fixing the detector module to the carrier plate, it has been found that according to a variant of the invention, a screw made of a metallic material is effective. Therefore, it is possible to discharge the heat generated during the operation of the detector module through the insertion plate, the connection means, and the support plate.

  According to an embodiment of the present invention, the array of detection elements may be an array of detection elements that directly converts X-rays. However, the array of detector elements may have one scintillator array and one photodiode array aligned relative to each other.

  Furthermore, according to an embodiment of the present invention, a collimator is arranged on the array of detection elements in order to allow only X-rays in a defined spatial direction to reach the array of detection elements.

  The problem concerning the detector is solved by an X-ray detector having a plurality of the above-mentioned detector modules. In this case, it is preferable that a plurality of detector modules are arranged on one carrier plate. According to an embodiment of the present invention, the carrier plate is configured such that a plurality of detector modules are arranged on the carrier plate in the front-rear direction. In order to construct a planar detector, a plurality of carrier plates having detector modules are finally arranged side by side. When a detector is provided for a computed tomography apparatus, a carrier plate with a detector module oriented in the direction of the system axis of the computed tomography apparatus is aligned in the φ direction on the detector arcuate body. Since it is arranged, the detector module is mounted on the cylindrical part surface.

Embodiments of the invention are illustrated in the accompanying schematic drawings.
FIG. 1 is a schematic diagram partially including a block diagram showing a computed tomography apparatus,
2 is a sectional view showing a detector module of the computed tomography apparatus of FIG.
3 is an exploded perspective view showing the detector module of FIG.
4 and 5 are plan views showing a printed circuit board having a recess.

  FIG. 1 shows a computer tomography apparatus 1 in a schematic diagram partially including a block diagram. The computed tomography apparatus 1 includes an X-ray source 2, and an X-ray beam 3 is emitted from a focal point F of the X-ray source 2. The X-ray beam 3 is formed, for example, in a fan shape or a pyramid shape by a known diaphragm not shown in FIG. The X-ray beam 3 passes through the inspection object 4 to be inspected and enters the X-ray detector 5. Although the X-ray source 2 and the X-ray detector 5 are not shown in FIG. 1, they are arranged on the rotating frame of the computed tomography apparatus 1 so as to face each other. The rotation frame can be rotated in the φ direction around the system axis Z of the computed tomography apparatus 1. During operation of the computed tomography apparatus 1, the X-ray source 2 and the X-ray detector 5 arranged in the rotation frame rotate around the inspection object 4, and X-ray images of the inspection object 4 are obtained from various projection directions. It is done. For each projection, the X-rays that pass through the inspection object 4 and are attenuated by passing through the inspection object 4 enter the X-ray detector 5. The X-ray detector 5 generates a signal corresponding to the intensity of the incident X-ray. As is well known, the image computer 6 calculates one or a plurality of two-dimensional or three-dimensional images of the inspection object 4 from the signals obtained by the X-ray detector 5, and the images can be displayed on the display device 7. .

  In the case of this embodiment, the X-ray detector 5 has a number of detector modules 8 arranged side by side in the φ direction and the Z direction on the detector arcuate body 29 that is a cylindrical partial surface. X-ray detector 5 is formed.

  FIG. 2 shows a typical example of the detector module 8 of the X-ray detector 5 in a sectional view. The detector module 8 has a vertical structure, and a scintillator array 10 is disposed on the photodiode array 11. Since the collimator 9 exists above the scintillator array 10, X-rays can reach the scintillator array 10 only from a predetermined spatial direction. The scintillator array 10 is structured and accordingly includes a number of scintillator elements not shown in detail. Each of these scintillator elements is attached to one photodiode of the photodiode array 11 including a large number of photodiodes. The scintillator array 10 and the photodiode array 11 are aligned relative to each other and bonded to each other. Accordingly, the scintillator array 10 and the photodiode array 11 form an array of X-ray detection elements, and one detection element has one scintillator element and one photodiode.

  In the present embodiment, the photodiode array 11 is disposed on the first printed circuit board 12. As can be seen from FIG. 3, the printed circuit board 12 has a solder region 13 so-called solder pad on the photodiode array 11 side. The photodiodes of the photodiode array 11 are arranged on an HTCC support material (HTCC = High Temperature Coated Ceramic) in this embodiment, and below the HTCC support material 12 via a solder ball 14. The solder region 13 is electrically connected.

  In the case of this embodiment, the printed circuit board 12 has a rectangular parallelepiped concave portion 15 that can be formed by milling, for example, on the side opposite to the photodiode array 11. The recess 15 is preferably configured such that the recess is surrounded or confined by an edge, so that the printed circuit board 12 has a so-called frame-like structure. However, the recess may be implemented in the form of a slit so that the recess is covered on the two sides of the edge and open on the two sides. The latter variant is advantageous when it comes to the production of the recesses. Both above-described embodiments of the recess are shown in plan view in FIGS. The bottom of the recess 15 is not clearly shown but has a conductor track. An electronic device necessary for processing the measurement signal supplied from the photodiode is arranged in the recess 15 of the printed circuit board 12, and the electronic device is connected to individual conductor paths for electrical connection. . The conductor path in the recess 15 is electrically connected to the solder region 13 through the printed circuit board 12 by a through hole in a manner not clearly shown. The electronic device for signal processing includes in particular at least one ASIC 16, but also includes other devices not explicitly shown, such as capacitors for supply voltage stabilization, amplifier circuits, etc. Since the electronic device in the recess 15 is arranged so as not to protrude from the recess 15, the recess 15 has a protective action for the electronic device.

  Furthermore, the recesses 15 in the printed circuit board 12 allow other printed circuit boards to be placed under the printed circuit board 12 in a simple manner. This is often necessary. This is because, as mentioned at the beginning, the electronic circuit device for processing the measurement signal supplied from the photodiode should be placed as close as possible to the photodiode for measurement technical reasons. This is because an occupied area 2 to 4 times larger than the detector surface of the module 8 itself is required. Therefore, in the case of this embodiment, the second printed circuit board 17 is arranged on the lower side of the printed circuit board 12 via the interposer 18. The second printed circuit board 17 also has a recess 19 configured in the same manner as the recess 15 of the first printed circuit board 12. In the recess 19 of the second printed circuit board 17 there are likewise conductor tracks and electronic devices for signal processing, which in this embodiment are two ASICs 20, 21. Similarly, since the electronic device is disposed in the recess 19 so as not to protrude from the recess 19, the recess 19 has a protective function for the electronic device.

  In both the first printed circuit board 12 and the second printed circuit board 17, the conductor paths are led to the edges of the respective printed circuit boards 12 and 17 by a method not shown. The printed circuit boards 12 and 17 are electrically connected to each other via a connecting cable guided between the conductor paths on the edge side of the both printed circuit boards 12 and 17 or preferably via a frame-like plug 22. It is. For this purpose, the opposite sides of the printed circuit boards 12, 17 have insertion contact portions 23 which cooperate with the insertion contact portions of the frame-like plug 22 having insertion contact portions on both sides. The plug-in contact portion 23 of the second printed circuit board 17 can be recognized in FIG.

  In this embodiment, the second printed circuit board 17 has a connection cable 24 for the electrical connection of the detector module 8 itself. The connection cable 24 is electrically connected to a conductor path of the second printed circuit board 17 through a through hole (not shown) penetrating the second printed circuit board 17, and through a frame-like plug 22. The first printed circuit board 12 is also electrically connected. The measurement signal generated from the photodiode is accordingly preprocessed by the electronic devices of the two printed circuit boards 12, 17 and subsequently connected to the detector module 8 via the cable 24 for continuous signal processing. The measurement signal transmitted to the electronic circuit device and finally processed reaches the computer 6. In this case, the processed measurement signal is guided to the image computer 6 via an interface (not shown), for example a slip ring, between the rotating part of the computed tomography apparatus 1 and the stationary part of the computed tomography apparatus 1. .

  Further, the above-described insertion plate 18 is accommodated in the frame-shaped plug 22 in the assembled state of the detector module 8. In particular, the ASICs 16, 20, 21 of both the printed circuit boards 12, 17 are disposed in the recesses 15, 19 so as to contact the interposer 18. Since the interposer 18 has a thermally conductive material, i.e. it is coated with this kind of material or is made entirely of metal, such as copper or aluminum, as in this embodiment, this way. Thus, the heat generated during the operation of the detector module 8, particularly the ASICs 16, 20, and 21, is exhausted from the detector module 8.

  This is because, among other things, the first printed circuit board 12, together with the detector array, the interposer 18 and the second printed circuit board 17, on the carrier plate 26, which also has a thermally conductive material, by metal screws 25. It is done by being fixed to. The support plate 26 has a heat guide path made of a metal material, for example copper, for heat dissipation, or in this embodiment is made entirely of a thermally conductive material, in particular metal.

  As can be seen from FIG. 3, the carrier plate 26 has a plurality of locations for the detector module 8, in this example five locations. The detector modules 8 are arranged on the carrier plate 26 so that detector bars or detector rows are constructed without large gaps between the detector modules 8. With respect to the X-ray detector 5 of the computed tomography apparatus 1 according to FIG. 1, a plurality of such detector rows oriented in the direction of the system axis Z of the computed tomography apparatus 1 are arranged in the φ direction to form a detector arc. It was placed on the body 29.

  The above-described configuration of the detector module 8 has the advantage that in particular it can be configured very compactly with a slight extension in the direction of the main centrifugal force corresponding to the direction of the normal of the detector module 8. Thereby, the X-ray detector as a whole can be made lighter in weight, thereby reducing the rotational mass which increases many times when the X-ray detector is operated at high rotational speeds. The reduced mechanical burden due to the lightweight construction reduces the deflection phenomenon. Therefore, the X-ray detector 5 has a stable dimension and an accurate position during operation. Thereby, not only the extension of the direction of the system axis Z can be expanded by the corresponding large configuration of the X-ray detector 5, but also the signal quality is improved by the short line length of the signal line in the detector. The occurrence of phonic effects is reduced.

  If more space is required for signal processing electronics in the detector module, the device described above can still be expanded as described above with one or more printed circuit boards in a vertical configuration. it can.

  However, if the signal processing electronics require little space, the detector module may typically contain only one printed circuit board that is arranged on the carrier plate without an interposer.

  Placing an interposer between the first printed circuit board and the second printed circuit board is only optional and can therefore be omitted.

  The detector module does not necessarily have to be screwed to the carrier plate. Rather, it can also be placed on the carrier plate by mounting hardware or other means.

Schematic showing a computed tomography apparatus with a detector assembled by a detector module according to the invention Sectional drawing which shows the detector module of the computer tomography apparatus of FIG. Exploded view showing the detector module of FIG. Plan view showing an example of a printed circuit board having a recess The top view which shows the other example of the printed circuit board which has a recessed part

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Computer tomography apparatus 2 X-ray source 3 X-ray beam 4 Inspection object 5 X-ray detector 6 Image computer 7 Display apparatus 8 Detector module 9 Detector plate 10 Scintillator array 11 Photodiode array 12 Printed circuit board 13 Solder area 14 Solder ball 15 Recess 16 ASIC
17 Printed circuit board 18 Insertion board 19 Recess 20 ASIC
21 ASIC
22 Frame-shaped plug 23 Plug-in contact portion 24 Connection cable 25 Metal screw 26 Carrier plate 29 Detector arcuate body F Focus Z System axis φ Rotation direction

Claims (24)

  An array of sensing elements and a first printed circuit board (12), the array of sensing elements being disposed on one side of the first printed circuit board (12), wherein the first printed circuit board (12) is at least Detector module comprising one recess (15), wherein at least one electronic device (16) used for signal processing is arranged in the recess (15).   A second printed circuit board (17) is disposed below the first printed circuit board (12), the second printed circuit board (17) has at least one recess (19), and the recess (19 The detector module according to claim 1, wherein at least one electronic device (20, 21) used for signal processing is arranged in the bracket.   3. The detector module according to claim 1, wherein the recesses (15, 19) are formed in a rectangular parallelepiped shape.   4. The detector module according to claim 1, wherein the recesses (15, 19) are formed in a slit shape.   The first and second printed circuit boards (12, 17) are connected to each other so that electrical signals can be transmitted from one printed circuit board (12, 17) to the other printed circuit board (12, 17). The detector module according to claim 2, wherein the detector module is provided.   The first and second printed circuit boards (12, 17) are framed so that electrical signals can be transmitted from one printed circuit board (12, 17) to the other printed circuit board (12, 17). 6. The detector module according to claim 2, wherein the detector modules are connected to each other by plugs (23).   One of the preceding claims, characterized in that at least one ASIC (16) is arranged in the recess (15) of the first printed circuit board (12) so as not to protrude from the recess (15). Detector module according to.   The at least one ASIC (20, 21) is arranged in the recess (19) of the second printed circuit board (17) so as not to protrude from the recess (19). The detector module according to one.   3. An insertion plate (18) having a thermally conductive material is arranged between the first printed circuit board (12) and the second printed circuit board (17). The detector module according to any one of 1 to 8.   The detector module according to claim 9, wherein the interposer plate is made of metal.   11. A detector module according to claim 9 or 10, characterized in that the interposer (18) is made of copper or aluminum.   12. Detector module according to one of claims 9 to 11, characterized in that at least one ASIC (16, 20, 21) abuts against the interposer (18).   13. Detector module according to one of the preceding claims, characterized in that it is arranged on a carrier plate (26) having a thermally conductive material.   Fixed on the carrier plate (26) by the connecting means (25) so that the heat released during operation of the detector module (8) can be discharged from the detector module (8) via the carrier plate (26). The detector module according to claim 13.   15. Detector module according to claim 13 or 14, characterized in that it is screwed to the carrier plate (26).   16. The detector module according to claim 1, wherein the array of detection elements is an array of detection elements that directly converts X-rays.   16. Detector module according to one of the preceding claims, characterized in that the array of detector elements comprises one scintillator array (10) and one photodiode array (11).   18. A detector module according to claim 1, wherein a collimator is arranged on the array of detector elements.   An X-ray detector comprising a plurality of detector modules according to claim 1.   20. Detector according to claim 19, characterized in that it has at least one carrier plate (26) in which a plurality of detector modules (8) are arranged.   21. Detector according to claim 20, characterized in that the detector modules (8) are arranged one after the other on the carrier plate (26).   The detector according to claim 20 or 21, characterized in that a plurality of carrier plates (26) having a detector module (8) are arranged in parallel.   23. A detector as claimed in one of claims 20 to 22, characterized in that the carrier plate (26) is arranged on the detector arcuate body (29).   Computer tomography apparatus comprising a detector (5) according to one of claims 19 to 23.

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