JP2008102088A - Radiation detector and radiation imaging apparatus - Google Patents

Abstract

It is possible to realize a detector field of view of a size that is freer than conventional ones, and in the event of a failure, only the semiconductor module can be easily removed, and even if a defect occurs in the detector module, the detection Provided are a semiconductor radiation detector capable of reducing damage when replacing a detector module, and a radiation imaging apparatus using the same.
A plurality of semiconductor elements are arranged in one direction and are detachably fixed to the upper end of a first signal processing board to form a first detector module. A plurality of the first detector modules 3 are juxtaposed in the longitudinal direction and fixed to the upper end of the second signal processing board to form a second detector module 9. A plurality of the second detector modules 9 are juxtaposed in the short direction and connected to the mother board 11 while being inserted and laminated with connecting bolts 10 to form a detector 12. The second detector module 9 is also detachable from the detector 12.
[Selection] Figure 3

Description

  The present invention relates to a radiation detector equipped in a gamma camera or the like, and more particularly to a radiation detector using a semiconductor. The present invention also relates to a radiation imaging apparatus provided with such a semiconductor radiation detector.

  For example, in a gamma camera, a radiation detector is one of the most important components for detecting gamma rays from a radioisotope (RI) injected into a subject. The energy resolution and further performance such as counting characteristics are greatly affected.

  Currently, scintillation type detectors occupy the mainstream of detectors. This is a structure in which light generated by a scintillator (phosphor) due to the incidence of gamma rays is detected by a plurality of photomultiplier tubes (PMT) or photodiode arrays arranged densely on the back surface thereof. This scintillation type detector is not only large and heavy, but also has the disadvantage of low energy resolution.

  Therefore, in recent years, semiconductor detectors are in the spotlight. Because it detects gamma rays directly, it has higher conversion efficiency to electrical signals than conventional scintillation type detectors that go through a two-step conversion process of gamma rays-light-electricity, and it detects gamma rays individually in a semiconductor cell. As a result, it is expected that the energy resolution and counting ability will be significantly improved.

  However, it is technically difficult to manufacture a large single crystal with a semiconductor material like a conventional NaI scintillator. For this reason, in order to realize a radiation detector for a gamma camera having a large field of view similar to the conventional one using a semiconductor material, a detector module composed of a plurality of small semiconductor elements is arranged in combination. It is realistic to secure a field of view.

  For example, as shown in FIG. 4A, a detector module 103 is formed by connecting a plurality of signal processing boards 102 to a plurality of semiconductor elements 101, and as shown in FIG. There is a system in which a detector 104 having a large visual field is configured by combining a plurality of detector modules 103.

  Here, one semiconductor element 101 is formed by arranging four semiconductor cells 105 in the vertical and horizontal directions. The semiconductor cell 105 has, for example, a size of 1 to 2 mm square and is made of a compound such as CdTe (cadmium telluride). Therefore, the size of the semiconductor element 101 is about 5 to 10 mm square, and five detector modules 103 are arranged in the vertical and horizontal directions in the figure, so the size is 25 to 50 mm square.

  Further, as shown in FIG. 5A, a single signal processing board is formed by combining a plurality of detector modules 103A composed only of a plurality of semiconductor elements 101 as shown in FIG. 5B. A method of constructing a detector 104A having a large visual field by mounting on 102A has also been studied.

  However, various problems have been pointed out with these conventional detector modules. First, since the size of the detector module is large, the size of a detector configured by combining the detector modules is restricted. That is, even if it is intended to obtain a detector having a desired size, it can be adjusted only in units of the size of the detector module, for example, 3 cm × 3 cm, both vertically and horizontally. However, since the semiconductor element is very expensive, it is desirable that the size of the detector can be adjusted by the smallest possible unit.

  In addition, when a failure occurs in the detector module located near the center of the detector, the detector module is large. The detectors must be removed one by one, and difficult work is required.

  Furthermore, since semiconductor elements are mechanically very fragile and easily broken, if a defective element or defective part occurs after the semiconductor element is once assembled as a detector module, the surrounding semiconductor elements are likely to be damaged. It is almost impossible to repair or replace these semiconductor elements without damaging them. As a result, the entire detector module must be replaced as defective. Therefore, when the detector module is large as in the prior art, damage caused when a defect occurs in the semiconductor element also increases.

In order to solve such a problem, a configuration has been proposed in which the detection element is detachably held and fixed to a detector module board (element holding means, element holding member) for each element. (For example, refer to Patent Document 1).
JP 2004-151089 A

  However, the detection element and the detector module board referred to in this proposal correspond to the semiconductor cell and the signal processing board in the above-described example, respectively. Thus, a large number of semiconductor cells can be detachably attached one by one. It takes a lot of time and effort and is not a realistic solution.

  Further, if minute semiconductor cells arranged densely are inserted and removed, there is a very high possibility of contact with adjacent semiconductor cells and damage.

  The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to provide a semiconductor radiation detector capable of realizing a detector field of view having a size larger than that of the conventional one and a radiation imaging apparatus using the semiconductor radiation detector. Is.

  Another object of the present invention is to provide a semiconductor radiation detector capable of easily removing only the semiconductor module when a failure occurs, and a radiation imaging apparatus using the semiconductor radiation detector.

  Still another object of the present invention is to provide a semiconductor radiation detector and a radiation imaging apparatus using the semiconductor radiation detector that can reduce damage when the detector module is replaced even if a defect occurs in the detector module. There is to do.

  In order to solve the above-described problem, a radiation detector according to the present invention includes a semiconductor element in which a semiconductor cell for detecting radiation forms a two-dimensional array in one direction as described in claim 1. A plurality of first detector modules arranged in a row and fixed to the upper end of the first signal processing board are formed, and a plurality of the first detector modules are juxtaposed in the longitudinal direction thereof. A second detector module is formed by being fixed, and a plurality of the second detector modules are juxtaposed in the short direction, and these second detector modules are formed by being connected by a mother board. .

  Preferably, the first detector module is preferably detachably fixed to the second signal processing board as described in claim 2, and the second detector module is Preferably, as described in claim 3, it is desirable that the motherboard is detachably connected.

  In order to solve the above-described problem, a radiation imaging apparatus according to claim 4 injects a radioactive substance into a subject and detects an intensity distribution of radiation generated from the radioactive substance, thereby detecting the inside of the subject. A radiation imaging apparatus for imaging a radiation detector has a plurality of radiation detectors for detecting the intensity of radiation generated from the radioactive substance, and the radiation detector includes a semiconductor cell for detecting radiation constituting a two-dimensional array. A plurality of formed semiconductor elements are arranged in one direction to form a first detector module fixed to the upper end of the first signal processing board, and a plurality of the first detector modules are arranged in parallel in the longitudinal direction. A second detector module is formed by being fixed to the upper end of the second signal processing board, and a plurality of the second detector modules are juxtaposed in the short direction. Le is one that is formed by connecting the motherboard.

  According to the semiconductor radiation detector and the radiation imaging apparatus using the semiconductor radiation detector according to the present invention, it is possible to realize a detector field of view having a size larger than that in the past.

  Further, the present invention provides an effect that only the semiconductor module can be easily removed when a failure occurs.

  Further, the present invention has an effect that even when a failure occurs in the detector module, damage caused when the detector module is replaced can be reduced.

  Embodiments of a semiconductor radiation detector according to the present invention will be described with reference to the accompanying drawings. FIG. 1 shows an outline of a first detector module 3 constituting a minimum unit that can be disassembled in the semiconductor radiation detector according to the present embodiment.

  The first detector module 3 includes four semiconductor elements 1 arranged in a line in the Y direction shown in the figure and a first signal processing board 2 as main elements.

  The semiconductor element 1 has a two-dimensional array in which, for example, four semiconductor cells 5 each having a square shape of approximately 1.6 mm square are arranged in each of the X and Y directions shown in FIG.

  The semiconductor cell 5 is formed by providing a cadmium telluride compound semiconductor crystal, such as CdTe or CdZnTe, with an application electrode surface and a signal extraction electrode surface, and is formed by a partition having an outer shape of about 7 mm square and a thickness of about 0.1 mm. Application (bias) electrodes (not shown) provided on the upper and lower sides of the respective electrode surfaces that are vertically arranged at equal intervals in the lattice and are substantially parallel to the radiation incident direction of each semiconductor cell 5. The signal extraction electrode is in contact.

  The first detector module 3 includes a single first signal processing board 2 for processing a signal from the semiconductor element 1 on a plurality of, for example, four semiconductor elements 1 arranged in a horizontal row. It has a combined structure. Then, the radiation detected by the detection element 1 is sent to the first signal processing board 2.

  The first signal processing board 2 is formed of a printed wiring board, converts radiation information detected by the detection element 1 into an electrical signal, and the electrical signal is transmitted to the outside via a connector 4 provided at the lower end. Is output.

  FIG. 2 shows an outline of a second detector module 9 formed by combining a plurality of such first detector modules 3. The second detector module 9 has a plurality of, for example, 10 pieces in the length direction of the first detector module 3 at one end of the second signal processing board 6 without a gap in a line in the Y direction shown in FIG. Are arranged in parallel.

  The first detector module 3 is screwed to the second signal processing board 6 with bolts and nuts (not shown). Accordingly, the first detector module 3 is provided so as to be removable from the second signal processing board 6.

  The second signal processing board 6 transmits and receives signals to and from the first detector module 3 via the connector 4, reads the output from each first detector module 3, and controls each detector module. I do.

  The second signal processing board 6 has a plurality of connecting holes 7 for connecting the second signal processing board 6 in the X direction, and a connector 8 for transmitting and receiving signals to the outside at one end. Is provided.

  Thereby, the magnitude | size of the Y direction shown to the same figure of a detector is determined. That is, the size in the Y direction is determined by the number of the first detector modules 3, and the length adjustment can be performed in units of the first detector modules 3. For example, in the present embodiment, since the first detector 3 is formed by arranging four 7 mm square detection elements 1, the size can be adjusted in units of 28 mm.

  FIG. 3 shows a semiconductor radiation detector 12 according to the present invention formed by combining a plurality of such second detector modules 9. The detector 12 includes a plurality of second signal processing boards 6 arranged in parallel in the X direction, and each second signal processing board 6 is electrically connected by a mother board 11.

  A connection bolt 10 is inserted into the connection hole 7 of the second signal processing board 6, and then a ring (not shown) is externally fitted to the connection bolt 10, and then a second second detector module 9 is inserted. The This ring plays a role of a spacer for keeping the distance between the second signal processing boards 6 and 6, and has a length obtained by subtracting the thickness of the second signal processing board 6 from the width of the detection element 1. Therefore, the detection elements 1 and 1 are densely arranged in the X direction without a gap. By repeating this operation, a desired number of second signal processing boards 9 can be stacked.

  Thus, since the 2nd detector module 6 is connected by the connecting bolt 10, the 2nd detector module 9 is provided so that removal from the detector 12 is possible.

  The mother board 11 is provided with a plurality of connectors (not shown) that are fitted to the connectors 8 of the second signal processing board 6 on the printed wiring board, and reads the outputs from all the second detector modules 9. And control all the second detector modules 9.

  Thus, the size of the detector in the vertical direction is determined by the number of stacked second signal processing boards 9.

  In particular, in the first detector module 3, since the detection elements 1 are not arranged in parallel in the X direction, the size in that direction is, for example, approximately 7 mm as in the present embodiment. The size of the direction detector can be adjusted in units of one semiconductor element 1, for example, in units of 7 mm.

  If any of the second detector modules 9 fails and needs to be replaced, first remove the motherboard and then remove the connecting bolt 10 to release the connection of the second detector module 9 Therefore, the target second detector module can be easily obtained without removing the second detector module 9 existing in the surroundings and without damaging the other normally operating second detector module 9. 9 can be extracted.

  Furthermore, if the failed first detector module 3 can be identified in the second detector module 9, the bolts and nuts fixing the second detector module 9 to the second detector module 9 can be removed to remove the first detector module 9. It is also possible to remove one detector module 3 and replace it with a normal first detector module 3 without damaging the other first detector module 3.

  As a result, replacement can be performed in smaller units, so that the cost of component replacement can be minimized.

  The embodiments described above are for illustrative purposes and do not limit the scope of the invention. Accordingly, those skilled in the art can employ embodiments in which each or all of these elements are replaced by equivalents thereof, and these embodiments are also included in the scope of the present invention.

The figure which shows the outline | summary of embodiment of the 1st detector module which comprises the semiconductor radiation detector which concerns on this invention. The figure which shows the outline | summary of the 2nd detector module which comprises the semiconductor radiation detector which concerns on this embodiment. The figure which shows the outline | summary of the semiconductor radiation detector which concerns on this embodiment. The figure which shows an example of the conventional detector module. The figure which shows the other example of the conventional detector module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor device 2 1st signal processing board 3 1st detector module 4 Connector 5 Semiconductor cell 6 2nd signal processing board 7 Connection hole 8 Connector 9 2nd detector module 10 Connection bolt 11 Motherboard 12 Detector

Claims (4)

A first detector module is formed in which a plurality of semiconductor elements in which semiconductor cells for detecting radiation constitute a two-dimensional array are arranged in one direction and fixed to the upper end of the first signal processing substrate,
A plurality of the first detector modules are juxtaposed in the longitudinal direction and fixed to the upper end of the second signal processing board to form a second detector module,
A radiation detector characterized in that a plurality of the second detector modules are juxtaposed in the short direction, and the second detector modules are connected by a mother board. The radiation detector according to claim 1, wherein the first detector module is detachably fixed to the second signal processing board. The radiation detector according to claim 1, wherein the second detector module is detachably connected to the motherboard. In the radiation imaging apparatus for imaging the inside of the subject by injecting a radioactive substance into the subject and detecting the intensity distribution of the radiation generated from the radioactive substance,
A plurality of radiation detectors for detecting the intensity of radiation generated from the radioactive material;
The above radiation detector
A first detector module is formed in which a plurality of semiconductor elements in which semiconductor cells for detecting radiation constitute a two-dimensional array are arranged in one direction and fixed to the upper end of the first signal processing substrate,
A plurality of the first detector modules are juxtaposed in the longitudinal direction and fixed to the upper end of the second signal processing board to form a second detector module,
A radiation imaging apparatus, wherein a plurality of the second detector modules are juxtaposed in the short direction, and the second detector modules are connected by a mother board.

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