JP2012078093A - Radiation detector and radiation detection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation detector and a radiation detection apparatus, which have excellent energy resolution.SOLUTION: A radiation detector 1 comprises a CdTe element 10 which has a plurality of pixels to detect radiation rays 4 on an incidence plane receiving the incoming radiation rays 4; a storage part 306b which stores location information of a pixel receiving the incoming radiation rays 4 and time information of a time of receiving the incoming radiation rays 4 as event information; a determination part 306a which determines that a first event corresponding to the incidence of radiation rays to a first pixel of the CdTe element 10 and a second event corresponding to the incidence of radiation rays to a second pixel of the CdTe element 10 are simultaneous events, when the time interval between the first event and the second event is shorter than a predetermined time interval; and a cancellation part 306c which cancels first event information of the first event and second event information of the second event in the storage part 306b, when the events are determined to be simultaneous.

Description

  The present invention relates to a radiation detector and a radiation detection apparatus.

  As a conventional technique, there is known a nuclear medicine diagnostic apparatus that determines a simultaneous event based on two or more signals output from two or more semiconductor cells of a detector that detects radiation (for example, Patent Document 1). reference).

  The nuclear medicine diagnosis apparatus described in Patent Document 1 detects these events as simultaneous events when the time difference is smaller than a predetermined threshold and the total energy of the two or more signals falls within a predetermined energy window. Is determined. Since the determined simultaneous event is not counted as an event, it is possible to reduce the probability of misidentification of the incident position due to scattering.

JP 2000-321357 A

  In the nuclear medicine diagnostic apparatus described in Patent Document 1, the output signal of the radiation detector is supplied to the signal processing circuit, and the simultaneous event determination is performed in the signal processing circuit. In this configuration, when the number of radiation detectors connected to the signal processing circuit is large or when the number of incident radiation is large, the number of output signals supplied from the radiation detector to the signal processing circuit increases. Since the load for determining the simultaneous event in the signal processing circuit increases, there is a possibility that the characteristics of the count rate deteriorate.

  Therefore, an object of the present invention is to provide a radiation detector and a radiation detection apparatus that efficiently determine simultaneous events and improve the characteristics of the count rate.

  In order to achieve the above object, the present invention provides a semiconductor element having a plurality of detection regions for detecting radiation on an incident surface on which radiation is incident, position information on the detection region on which radiation is incident, and time information on the time of incidence. In a first storage unit that stores event information, a first event in which radiation enters the first detection region of the semiconductor element, and a second event in which radiation enters the second detection region of the semiconductor element, A first determination unit that determines that the first event and the second event are simultaneous events when the time interval between the first event and the second event is shorter than a predetermined time interval; And a first discard unit that discards the first event information of the first event and the second event information of the second event from the first storage unit. .

  In the radiation detector, the first determination unit has a time interval between the first event and the second event shorter than a predetermined time interval, and the first detection region to the second detection region. It is preferable that the first event and the second event are determined as simultaneous events when the distance to is within a predetermined range.

  In addition, the radiation detector may be configured such that a predetermined range is an 8-connected detection region based on a detection region on which radiation is incident, or a detection region around the 8-connected detection region and the 8-connected detection region. Preferably there is.

  In addition, the radiation detection apparatus includes the plurality of radiation detectors described above, one of the plurality of radiation detectors includes a first detection region, and the other radiation detector includes a second detector. It is preferable to include a second determination unit that has a detection region and determines a simultaneous event based on event information output from one radiation detector and another radiation detector.

  The radiation detection apparatus also includes a second storage unit that stores the first event information and the second event information, and the first event and the second event that are determined as simultaneous events by the second determination unit. It is preferable to include a second discard unit that discards the first event information and the second event information from the second storage unit.

  In the radiation detection apparatus, the plurality of radiation detectors described above are connected to each other with mutual communication units, and a third event occurs in one radiation detector of the plurality of radiation detectors. When the fourth event occurs in the other radiation detectors of the plurality of radiation detectors, the first determination unit of the one radiation detector passes through the mutual communication unit of the first radiation detector. It is preferable that event information of the fourth event is acquired from the radiation detector and a simultaneous event is determined based on the acquired event information of the fourth event.

  In addition, the radiation detection apparatus discards the first discarding unit of one radiation detector discarding the event information of the third event determined to be a simultaneous event, and further discarding the event information of the fourth event It is preferable to generate information and output it to another radiation detector via the mutual communication unit.

  In the radiation detection apparatus, it is preferable that the first discarding unit of one radiation detector stops outputting the event information of the third event determined as the simultaneous event.

  In the radiation detection apparatus, the first determination unit of the other radiation detector acquires event information of the third event from the one radiation detector via the mutual communication unit of the other radiation detector. The simultaneous event is determined based on the event information of the third event, and the first discarding unit of the other radiation detector stops the output of the event information of the fourth event determined to be the simultaneous event. preferable.

  According to the radiation detector and the radiation detection apparatus of the present invention, it is possible to provide a radiation detector and a radiation detection apparatus that efficiently determine simultaneous events and improve the characteristics of the count rate.

FIG. 1 is a perspective view of the radiation detector according to the first exemplary embodiment. FIG. 2 is a perspective view of an edge-on type radiation detection apparatus configured by arranging a plurality of radiation detectors according to the first embodiment. FIG. 3 is a block diagram of the radiation detection circuit and its peripheral circuits according to the first embodiment. FIG. 4 is a schematic view of the radiation detector according to the first embodiment viewed from the incident surface side. FIG. 5 is a schematic view of the radiation detectors arranged in the radiation detection apparatus according to the first embodiment when viewed from the incident surface side. FIG. 6 is a flowchart regarding the radiation detector according to the first exemplary embodiment. FIG. 7 is a flowchart relating to the radiation detection apparatus according to the first embodiment. FIG. 8 is a block diagram of the radiation detection circuit and its peripheral circuits according to the second embodiment. FIG. 9 is a flowchart according to the second embodiment.

[Summary of embodiment]
In the radiation detector according to the embodiment, a semiconductor element having a plurality of detection areas for detecting radiation on an incident surface on which radiation is incident, position information on the detection area on which the radiation is incident, and time information on the incident time are events. In a first storage unit that stores information, a first event in which radiation enters the first detection region of the semiconductor element, and a second event in which radiation enters the second detection region of the semiconductor element, A first determination unit that determines that the first event and the second event are simultaneous events when the time interval between the first event and the second event is shorter than a predetermined time interval; A first discard unit that discards the first event information of the first event and the second event information of the second event from the first storage unit.

[First Embodiment]
(Outline of configuration of radiation detector 1)
FIG. 1 is a perspective view of the radiation detector according to the first exemplary embodiment. FIG. 2 is a perspective view of an edge-on type radiation detection apparatus configured by arranging a plurality of radiation detectors according to the first embodiment. The radiation detector 1 according to the present embodiment is a radiation detector that detects radiation such as γ rays and X rays. In FIG. 1, the radiation 4 enters from the top to the bottom of the page. That is, the radiation 4 propagates along the direction from the CdTe element 10 as the semiconductor element of the radiation detector 1 toward the card holder 13 and enters the radiation detector 1.

  In the radiation detector 1, the radiation 4 is incident on each side surface of the CdTe element 10 (that is, the surface facing upward in FIG. 1). Therefore, each side surface of the CdTe element 10 is an incident surface for the radiation 4. In this way, a radiation detector whose side surface of the semiconductor element is the incident surface of the radiation 4 is referred to as an edge-on type radiation detector.

  The radiation detector 1 detects the radiation 4 via a collimator having a plurality of openings through which the radiation 4 incident along a specific direction (for example, a direction from the subject toward the radiation detector 1) passes. The radiation detector 1 for an edge-on type radiation detection apparatus configured by arranging a plurality of radiation detectors 1 arranged side by side can be configured. In addition, when using a collimator, a porous parallel collimator, a pinhole collimator, etc. can be used. The present embodiment can also be applied to a radiation detector that is not an edge-on type. Further, the radiation detector 1 according to the present embodiment has a card shape.

  The substrate 11 of the radiation detector 1 is sandwiched and supported by the card holder 13 and the card holder 14. The card holder 13 and the card holder 14 are formed to have the same shape, and the protrusion 17 of the card holder 14 is fitted into the grooved hole 18 of the card holder 13, and the grooved of the card holder 14 is provided. The board | substrate 11 is supported by the projection part 19 which the card holder 13 has fitted in the hole (not shown).

  Further, the elastic member mounting portion 15 presses and fixes the radiation detector 1 to the radiation detector stand 5a when the radiation detector 1 is inserted into the radiation detector stand 5a that supports the plurality of radiation detectors 1. This is a portion where the elastic member 16 is provided. The radiation detector stand 5 a has a connector 52 into which the card edge portion 29 is inserted. The radiation detector 1 has a pattern formed on the card edge portion 29 by inserting the card edge portion 29 into the connector 52. When 29a and the connector 52 are electrically connected, they are electrically connected to an overall radiation detection circuit described later.

  In the radiation detector 1, for example, four CdTe elements 10 are arranged at a constant interval on one side of the substrate 11, and four CdTe elements 10 are arranged at a constant interval on the other side.

  The flexible substrate 12 is a substrate formed using, for example, a film-like resin (for example, polyimide).

  The flexible substrate 12 includes a substantially semicircular connection portion 120 to a connection portion 123 at a lower portion with respect to the paper surface of FIG. The connection part 120 to the connection part 123 are patterns formed using a conductive material, and are formed using Cu or the like, for example. As shown in FIG. 1, the connection unit 120 is configured to be electrically connected to the board terminal 20. Similarly, the connection portion 121 is configured to be electrically connected to the substrate terminal 21, the connection portion 122 is electrically connected to the substrate terminal 22, and the connection portion 123 is electrically connected to the substrate terminal 23. In FIG. 1, illustration of a substrate terminal electrically connected to the flexible substrate on the opposite side of the flexible substrate 12 and the flexible substrate on the opposite side is omitted.

  Further, a plurality of grooves (not shown) provided in the CdTe element 10 are provided at substantially equal intervals on the element surface. Furthermore, the CdTe element 10 has seven grooves as an example.

  Each portion of the CdTe element divided by the groove corresponds to one pixel (pixel) as a detection region for detecting the radiation 4. Thereby, one CdTe element has a plurality of pixels. When one radiation detector 1 includes eight CdTe elements 10 and one CdTe element 10 includes eight pixels, one radiation detector 1 has a resolution of 64 pixels. By increasing or decreasing the number of grooves, the number of pixels of one CdTe element 10 can be increased or decreased.

  In addition, the substrate 11 has a width on the first end side on which each of the plurality of CdTe elements 10 is mounted, and a second end on the opposite side of the first end side on which the plurality of CdTe elements 10 are mounted. It is formed wider than the part side. The substrate 11 is supported by the card holder 13 and the card holder 14 on the second end side. Further, a card edge portion 29 provided with a plurality of patterns 29a capable of electrically connecting the radiation detector 1 and an external control circuit is provided on the second end side. Further, between the element connection part (not shown) formed on the substrate 11 that is electrically connected to the CdTe element 10 and the card edge part 29, each of the plurality of CdTe elements 10 is connected via the element connection part. A plurality of electronic component mounting portions 3 for mounting a radiation detection circuit to be described later are provided. Note that an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or the like other than the radiation detection circuit may be mounted on the electronic component mounting unit 3.

  In addition, the board | substrate 11 has a length of about 40 mm in the wide direction, ie, a longitudinal direction, as an example. The substrate 11 extends from the end of the wide portion to the end of the narrowed portion, that is, from the end of the portion where the element connecting portion is provided to the end of the card edge portion 29. In FIG. 2, the length is about 20 mm.

In the present embodiment, for example, CdTe is used as a compound semiconductor constituting the semiconductor element, but the compound semiconductor is not limited to this. For example, a compound semiconductor such as a CdZnTe (CZT) element or an HgI ₂ element that detects radiation such as γ-rays. An element can also be used.

  As shown in FIG. 2, the radiation detection apparatus 5 according to the present embodiment is configured by holding a plurality of radiation detectors 1 by a radiation detector stand 5a. Specifically, a plurality of supports in which a plurality of grooves 511 into which the plurality of radiation detectors 1 are inserted are arranged at a predetermined distance according to the interval at which the plurality of radiation detectors 1 are arranged. 51, a support plate 50 on which the support body 51 is mounted, and a plurality of support bodies 51, and each of the card edge portions 29 of the plurality of radiation detectors 1 are connected to each other to connect the total radiation detection circuit and the plurality of radiations. A plurality of radiation detectors 1 are held in a radiation detector stand 5 a including a plurality of connectors 52 that connect each of the detectors 1. A plurality of radiation detectors 1 according to the present embodiment are inserted into and fixed to each of the plurality of grooves 511 of the support 51, whereby a radiation detection apparatus 5 as shown in FIG. 2 is configured.

  The plurality of supports 51 are provided on the support plate 50 with an interval corresponding to the width of the radiation detector 1. Each of the plurality of supports 51 has a plurality of wall portions 510, and a groove 511 is formed between the wall portions 510. The wall portion 510 is provided with a recess 512 on one surface, and the other surface is a flat surface 513. In the elastic member mounting portion 15 of the radiation detector 1, for example, an elastic member 16 formed using sheet metal is incorporated, and when the radiation detector 1 is inserted into the groove 511 of the support 51, this elastic member 16, the radiation detector 1 is pressed against the flat surface 513 of the wall portion 510, whereby the radiation detector 1 is fixed to the support 51. Each of the plurality of supports 51 can be formed from a metal material by cutting or the like.

  Although not shown in FIG. 2, a collimator having a plurality of openings is provided above the plurality of radiation detectors 1, that is, on the opposite side of the support plate 50 of the radiation detector 1. By using a collimator, only radiation from a specific direction can be detected by the CdTe element. As an example, the plurality of openings of the collimator are formed in a substantially square shape. As an example, the size of the opening diameter of the plurality of openings is formed such that one side is 1.2 mm, and the openings are arranged in a matrix at a pitch of 1.4 mm. Therefore, in the collimator, the thickness of the wall portion separating one opening and another opening adjacent to the one opening is 0.2 mm.

(Configuration of radiation detection circuit 30)
FIG. 3 is a block diagram of the radiation detection circuit and its peripheral circuits according to the first embodiment. The radiation detection circuit 30 according to the present embodiment is mounted on the electronic component mounting unit 3. Further, the comprehensive radiation detection circuit 100 according to the present embodiment is mounted on the radiation detector stand 5 a of the radiation detection apparatus 5. Below, the structure of the radiation detection circuit 30 is demonstrated.

  When the radiation 4 enters the CdTe element 10 and interacts with it (photoelectric effect, Compton scattering, or electron pair generation), the atoms in the CdTe element 10 are ionized, and pairs of electrons and holes are generated. . Since the number of pairs is proportional to the energy of the incident radiation 4, it is possible to obtain excellent energy determination accuracy (energy resolution) by accurately reading out the energy.

  When electrons and holes generated in the CdTe element 10 are merely incident on the CdTe element 10, they recombine and disappear. Therefore, by applying a high voltage (for example, 600V) bias voltage between the positive electrode and the negative electrode provided with the CdTe element 10 interposed therebetween, an electric field is generated between the electrodes, so that electrons move toward the positive electrode. However, the holes move toward the negative electrode. The radiation detection circuit 30 of the radiation detector 1 is a circuit that reads out and outputs this movement as a signal.

  As shown in FIG. 3, the radiation detection circuit 30 includes a capacitor 300, a preamplifier 301, a shaping amplifier 302, a peak hold 303, an A / D conversion unit 304, and a trigger generation unit 305 in one pixel of the CdTe element 10. A detection circuit is provided. That is, the radiation detection circuit 30 includes, for example, the same number of detection circuits as the number of pixels of the CdTe element 10.

  The radiation detection circuit 30 includes an event determination unit 306, a data buffer 307, a control unit 308, and a first communication unit 309.

  The capacitor 300 is connected to the positive electrode side of the CdTe element 10, for example. This capacitor 300 is a coupling capacitor, cuts off the direct-current voltage component, and transmits only the change in the charge generated in the CdTe element 10 to the preamplifier 301 via this capacitor 300.

  The preamplifier 301 is connected to a terminal opposite to the positive electrode side terminal of the capacitor 300. The preamplifier 301 amplifies the radiation detection signal output from the positive electrode via the capacitor 300.

  The shaping amplifier 302 performs waveform shaping and amplification of the amplified signal output from the preamplifier 301.

  The peak hold 303 is configured to output a signal for holding the wave height of the waveform-shaped signal output from the shaping amplifier 302 constant. The signal output from the peak hold 303 is input to the A / D conversion unit 304 and the trigger generation unit 305.

  The trigger generation unit 305 generates a pulse-shaped trigger signal and outputs it to the A / D conversion unit 304. In addition, the trigger generation unit 305 is based on the signal output from the peak hold 303, the position information that is information of the pixel on which the radiation is incident, and the time that is the information on the time when the signal output from the peak hold 303 is input. Information is generated, and event information including position information and time information is generated. The trigger generation unit 305 is configured to output the generated event information to the event determination unit 306.

  When the trigger signal output from the trigger generation unit 305 is input, the A / D conversion unit 304 is configured to convert the signal output from the peak hold 303 into a digital signal and output the digital signal. This digital signal is stored in the data buffer 307.

  The event determination unit 306 includes a determination unit 306a as a first determination unit, a storage unit 306b as a first storage unit, and a discard unit 306c as a first discard unit. .

  The determination unit 306a determines a simultaneous event described later. Based on the event information output from the trigger generation unit 305, the determination unit 306a is generated within a predetermined time interval and the distance between pixels in which the event has occurred is within a predetermined range. In this case, at least two events that satisfy this condition are determined as simultaneous events. In the following, the predetermined time interval is described as a set range, and the predetermined range is described as a proximity range.

  For example, the storage unit 306b temporarily stores information when performing the determination, and is configured using a semiconductor memory such as a RAM (Random Access Memory). The storage unit 306b is configured to output the stored event information to the data buffer 307 when no other event information is stored within a predetermined period after storing the event information, for example.

  The discarding unit 306c discards event information determined as a simultaneous event from the storage unit 306b.

  The control unit 308 is, for example, a microcomputer including a CPU (Central Processing Unit) and the like, and controls the first communication unit 309 and the like.

  The first communication unit 309 outputs the digital signal and event information stored in the data buffer 307 to the comprehensive radiation detection circuit 100.

  Further, the radiation detection apparatus 5 includes a comprehensive radiation detection circuit 100 that determines a simultaneous event from a plurality of event information output from the plurality of radiation detectors 1.

  The total radiation detection circuit 100 includes a communication unit 101, a total event determination unit 102, and a data buffer 103, and is schematically configured.

  The communication unit 101 is connected to the first communication unit 309 of all the radiation detectors 1 through the connector 52 of the radiation detector stand 5a.

  The general event determination unit 102 is roughly configured to include a determination unit 102a as a second determination unit, a storage unit 102b as a second storage unit, and a discard unit 102c as a second discard unit. Yes.

  The determination unit 102 a determines a simultaneous event across the radiation detector 1 based on the event information for each radiation detector 1 acquired via the communication unit 101. That is, the determination unit 102a generates at least two events that occur within a predetermined time interval and within a predetermined range based on the acquired event information for each radiation detector 1. Are determined as simultaneous events.

  For example, the storage unit 102b temporarily stores information when making a determination, and is configured using a semiconductor memory such as a RAM.

  The discarding unit 102c discards event information determined as a simultaneous event across a plurality of radiation detectors 1.

  The data buffer 103 stores event information that has not been determined as a simultaneous event by the general event determination unit 102. For example, after the data buffer 103 is output, the stored event information is subjected to correction processing for correcting the wave height, output to the external device, visualized by the external device, and displayed on the display device.

(About judgment of simultaneous event)
FIG. 4 is a schematic view of the radiation detector according to the first embodiment viewed from the incident surface side. The numbers and letters shown on the vertical axis and the horizontal axis in FIG. 4 are attached to indicate the positions of the pixels. For example, the pixel on the upper surface of FIG. , the horizontal axis coordinates so B, and shall be referred to as pixels B _11. That is, as shown in FIG. 2, one radiation detector 1 has a total of 64 pixels including pixels A ₁ to A ₃₂ and pixels B _{1 to} B ₃₂ .

  Hereinafter, determination of a simultaneous event by the determination unit 306a of the event determination unit 306 will be described.

For example, when energy radiation 4 280keV enters the pixel _{B 11} of the radiation detector 1, the pixel _{B 11,} lose energy of 140keV interaction of radiation 4 and the CdTe element 10 (Compton scattering) is generated, Furthermore, it is conceivable that the energy (140 keV) is lost by causing an interaction (photoelectric effect) upon entering another pixel.

  Since the energy of radiation generated from the medicine administered for medical use is approximately 140 keV, the radiation detector 1 detects two events. That is, in the above case, the radiation detector 1 detects a false event in which no radiation is actually incident. An event indicates that radiation is incident.

  When this false event occurs, when it is converted into image information and visualized by an external device, the false event is displayed on the visualized image, resulting in a reduction in image quality.

  Accordingly, the determination unit 306a of the present embodiment determines at least two events that occur within a predetermined time interval and within a predetermined range as simultaneous events, and further, Since the event information determined as the simultaneous event is discarded by the discarding unit 306c, the false event can be eliminated, and the energy resolution is improved. In addition, when the magnitude | size of the radiation detector 1 with which the 2nd event may be detected in any pixel of the radiation detector 1 is small, or when the energy of radiation is large, it is predetermined as mentioned above. There is no need for the condition to be within the range (proximity range).

Note that since radiation easily interacts with a semiconductor element, the Compton-scattered radiation at the first pixel is unlikely to cause a wide range of scattering across multiple pixels. That is, the pixel in which the second event has occurred is located in the vicinity of the pixel in which the first event has occurred. Here, as shown in FIG. 4, the radiation incident on the pixel B ₁₁ is the scattering hardly thought to be incident on the pixel A _21. For example, even if the time interval between two events is within the set range, the distance between the pixel B ₁₁ and the pixel A ₂₁ is not within the proximity range, and therefore the determination unit 306a is based on the position information of the two event information. Thus, it is determined that the two events are generated independently.

Therefore, as an example, the determination unit 306a according to the present embodiment includes, in one radiation detector 1, a pixel that is positioned obliquely with a pixel adjacent to the pixel in which the first event has occurred, that is, the first event. The determination is made by setting the pixels connected to the pixels where the occurrence of 8 and the surrounding pixels of the 8 connected pixels as a set range. Note that the adjacent pixels are pixels located at the pixel A ₁₁ , the pixel B _10, and the pixel B ₁₂ when the radiation 4 is incident on the pixel B ₁₁ , for example, as shown in FIG. Further, the diagonally positioned pixels are pixels positioned at the pixel A ₁₀ and the pixel A ₁₂ when the radiation 4 is incident on the pixel B ₁₁ as shown in FIG. 4, for example. Further, the surrounding pixels of 8-connected pixels, for example, as shown in FIG. 4, when the radiation 4 is incident on the pixel _{B 11,} located in the pixels _{A 9,} pixels _{A 13,} pixels _{B 9} and pixel _{B 13} The pixel to be. Note that the proximity range is not limited to the above example, and may be 8-connected pixels with reference to the pixel on which the radiation is incident, or a range up to a pixel adjacent to a pixel adjacent to the 8-connected pixel. Also good. The proximity range can be changed according to the area of the pixel and the energy of the radiation.

  In addition, the determination unit 306a sets a time interval between the time obtained based on the time information included in the event information of the first event and the time obtained based on the time information included in the event information of the second event. It is configured to ask for. As an example, this time interval is 1 μsec. That is, the determination unit 306a determines that the time interval between the time of the first event and the time of the second event is shorter than a predetermined time interval, and the pixel in which the first event has occurred and the second event are When the generated pixel occurs within a predetermined range, it is determined as a simultaneous event. In addition, when a plurality of events satisfy the above conditions, these events are regarded as simultaneous events.

FIG. 5 is a schematic view of the radiation detectors arranged in the radiation detection apparatus according to the first embodiment when viewed from the incident surface side. FIG. 5 illustrates a part of the radiation detectors 1 a to 1 e arranged in the radiation detection device 5. In FIG. 5, numbers 1 to 12 are assigned vertically and characters A to J are assigned horizontally for each pixel with reference to the upper left of the page. Therefore, the shaded upward sloping radiation 4 is incident is attached pixels, 7th vertically, since it is the sixth next to (F th) pixels, shown as pixels F _7. A diagonal line rising to the right in FIG. 5 indicates a pixel on which radiation is incident, and a diagonal line rising to the left on the periphery indicates a proximity range with respect to the incident pixel.

  In the above, the determination of the simultaneous event in one radiation detector 1 has been described. However, in the radiation detection apparatus 5 in which a plurality of radiation detectors 1 are arranged at a narrow interval, the second event is the other radiation detector 1. It may also occur.

For example, as shown in FIG. 5, when the radiation 4 is incident on the pixel F ₇ , the pixel E ₆ to the pixel E ₈ , the pixel F ₆ , the pixel F ₈ , and the pixel G ₆ to the pixel G ₈ are It is an area. In addition, the pixel D ₅ to the pixel D ₉ , the pixel E ₅ , the pixel E ₉ , the pixel F ₅ , the pixel F ₉ , the pixel G ₅ , the pixel G ₉ , and the pixel H ₅ to the pixel H ₉ are an 8-connected peripheral region. It becomes. That is, the proximity region extends from the radiation detector 1b to the radiation detector 1d, for example, as shown in FIG.

  The determination unit 102 a of the general event determination unit 102 determines a simultaneous event based on a plurality of event information acquired from the plurality of radiation detectors 1. Below, operation | movement of the radiation detection apparatus 5 which concerns on this Embodiment is demonstrated. First, the operation of the radiation detection circuit 30 of the radiation detector 1 will be described with reference to the flowchart of FIG.

(Operation of the first embodiment)
When a first event occurs in which the radiation 4 enters the pixel F ₇ of the radiation detector 1c shown in FIG. 5 (S1), the radiation detection signal output from the CdTe element 10 of the radiation detector 1c is a capacitor 300, Input to the peak hold 303 via the preamplifier 301 and the shaping amplifier 302.

  The peak hold 303 generates a signal that keeps the wave height of the input signal constant, and outputs the signal to the A / D converter 304 and the trigger generator 305.

  The A / D conversion unit 304 converts the input signal based on the trigger signal output from the trigger generation unit 305 to generate a digital signal, and stores the digital signal in the data buffer 307.

  The trigger generation unit 305 generates a trigger signal from the input signal, outputs the trigger signal to the A / D conversion unit 304, generates event information, and outputs the event information to the event determination unit 306.

  The event determination unit 306 stores the input event information in the storage unit 306b.

  Subsequently, when a second event occurs (S2), the trigger generation unit 305 generates event information based on signals input via the CdTe element 10, the capacitor 300, the preamplifier 301, the shaping amplifier 302, and the peak hold 303. And output to the event determination unit 306.

The determination unit 306a of the event determination unit 306 determines whether or not the first event and the second event are within the proximity range based on the event information. More specifically, the determination unit 306a, based on the pixel F ₇ in which the first event occurs, a predetermined range, a pixel to be 8-connected, and surrounding the 8-connected pixels pixels, the It is determined whether a second event has occurred.

However, the determination unit 306a, so determined only for the range of the radiation detector 1c, as a range, the pixels _{E 5} ~ pixels _{E 9,} pixel _{F 5,} pixel _{F 6,} pixel _{F 8,} a pixel _{F 9.} The presence or absence of event occurrence in the other ranges of the pixel D ₅ to the pixel D _{9 of} the radiation detector 1b and the pixel G ₅ to the pixel G ₉ and the pixel H ₅ to the pixel H ₉ of the radiation detector 1d depends on the total radiation detection in the subsequent stage This is done in circuit 100.

  When the second event occurs within the proximity range (S3; Yes), the determination unit 306a determines whether the time interval from the occurrence of the first event to the occurrence of the second event is within the set range. judge.

  When the time interval from the occurrence of the first event to the occurrence of the second event is within the setting range (S4; Yes), the determination unit 306a determines that the discard unit 306c determines the first event based on the determination result. The event information of the second event is discarded from the storage unit 306b (S5).

  Here, in Step 3, when the second event occurs in a pixel outside the proximity range (S3; No), the determination unit 306a receives the event information of the first event and the second event from the storage unit 306b. The event information is read and stored in the data buffer 307 (S6). In the following, it is assumed that event information stored in the data buffer 307 is associated with a digital signal output from the A / D conversion unit 304.

  Subsequently, the control unit 308 reads the event information from the data buffer 307 and outputs the event information via the first communication unit 309 (S7).

  In Step 4, when the time interval from the occurrence of the first event to the occurrence of the second event is longer than the set range (S4; No), the determination unit 306a executes Step 6 and Step 7.

  Up to this point, the operation of the radiation detector 1 has been described. Subsequently, the operation of the integrated radiation detection circuit 100 will be described with reference to the flowchart of FIG.

  The comprehensive event determination unit 102 of the comprehensive radiation detection circuit 100 acquires event information of each radiation detector 1 via the communication unit 101 (S10). The acquired event information is temporarily stored in the storage unit 102b of the general event determination unit 102.

  When the determination unit 102a of the general event determination unit 102 determines the occurrence of the first event based on the acquired event information, the determination unit 102a subsequently determines the second event within the proximity range based on the pixel where the first event has occurred. Determine whether an event has occurred. This determination is performed in the radiation detector 1b and the radiation detector 1d adjacent to the radiation detector 1c in which the first event has occurred. Depending on the arrangement of the radiation detectors 1 in the radiation detection device 5 and the position of the pixel on which the radiation is incident, not only the radiation detectors in the horizontal direction but also the radiation detectors adjacent in the vertical direction on the paper surface of FIG. A determination is also made.

  When the second event occurs in the adjacent radiation detector 1b and radiation detector 1d (S11; Yes), the determination unit 102a determines whether the first event and the second event are within the proximity range. Determine whether or not.

  When the second event occurs within the proximity range (S12; Yes), the determination unit 102a determines whether the time interval from the occurrence of the first event to the occurrence of the second event is within the set range. judge.

  When the time interval from the occurrence of the first event to the occurrence of the second event is within the set range (S13; Yes), the determination unit 102a determines that the discard unit 102c determines the first event based on the determination result. The event information of the second event is discarded from the storage unit 102b (S14).

  Here, in step 11, when the second event does not occur in the adjacent radiation detector 1b and radiation detector 1d (S11; No), the determination unit 102a determines the first event and the second event. Event information is stored in the data buffer 103 (S15).

  In Step 12, when the second event occurs in a pixel outside the proximity range (S12; No), the determination unit 102a reads the event information of the first event and the second event from the storage unit 102b. The event information of the first event and the second event is stored in the data buffer 103 (S15).

  Further, in step 13, when the time interval from the occurrence of the first event to the occurrence of the second event is longer than a predetermined time interval (S13; No), the determination unit 102a determines that the first event and The event information of the second event is stored in the data buffer 103 (S15).

(Effects of the first embodiment)
According to the radiation detector 1 according to the present embodiment, the event information determined to be a simultaneous event is discarded before the event information is output to the integrated radiation detection circuit 100, and therefore the detector that does not determine the simultaneous event. The amount of information to be output can be reduced compared to.

  Further, according to the radiation detection apparatus 5 according to the present embodiment, before the event information is output to the comprehensive radiation detection circuit 100 in the radiation detector 1, the event information determined to be a simultaneous event is discarded, and the total radiation is detected. In the detection circuit 100, the simultaneous event generated across the radiation detectors is discarded. As a result, the amount of information output from the radiation detector 1 to the comprehensive radiation detection circuit 100 can be reduced, and the simultaneous event determination load in the comprehensive radiation detection circuit 100 can be reduced. Therefore, simultaneous determination of simultaneous events can be efficiently performed in the entire radiation detection apparatus 5, and the characteristics of the count rate can be improved.

[Second Embodiment]
The second embodiment is different from the first embodiment in that adjacent radiation detectors are connected to each other. In the second embodiment described below, parts having the same configurations and functions as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted. .

(Configuration of radiation detector 1)
FIG. 8 is a block diagram of the radiation detection circuit and its peripheral circuits according to the second embodiment.

  As shown in FIG. 8, the radiation detector 1 according to the present exemplary embodiment includes a second communication unit 310 as an intercommunication unit that communicates with adjacent radiation detectors.

  The second communication unit 310 is connected to the second communication unit of the adjacent radiation detector by a communication line 311. Below, operation | movement of the radiation detection apparatus 5 which concerns on 2nd Embodiment is demonstrated according to the flowchart of FIG. The determination of the simultaneous event in the radiation detector in which the event has been detected is the same as in the first embodiment. Therefore, in the following, the radiation detector 1c in which the first event has occurred is adjacent to the radiation detector 1c shown in FIG. The determination of the simultaneous event that occurs across the matching radiation detector 1b or radiation detector 1d will be described.

  In the present embodiment, the second communication unit 310 communicates with the second communication unit of the adjacent radiation detector. However, the present invention is not limited to this, for example, the condition of being in the proximity range described above In the case where there is not, or when the proximity range extends to a radiation detector outside the adjacent radiation detector, communication with other radiation detectors in the set range may be performed to determine a simultaneous event. However, it may be configured to perform communication with all communicable radiation detectors and determine a simultaneous event.

(Operation of Second Embodiment)
First, as in the first embodiment, when a first event (third event) in which radiation enters the pixel F ₇ shown in FIG. 5 occurs (S 20), event information is input to the event determination unit 306. Then, the determination unit 306a of the event determination unit 306 determines a simultaneous event of the same radiation detector 1c (one radiation detector) and determines a simultaneous event of the adjacent radiation detector 1b and the radiation detector 1d. Therefore, event information is acquired via the communication line 311 and the 2nd communication part 310 (S21).

  The determination unit 306a of the radiation detector 1c includes the second event (fourth event) within the proximity range of the first event based on the event information of the radiation detector 1b and the radiation detector 1d as other radiation detectors. ) Exists.

  The determination unit 306a of the radiation detector 1c has a time interval from the occurrence of the first event to the occurrence of the second event when the second event exists within the proximity range of the first event (S22; Yes). Is determined to be within the set range.

  When the time interval from the occurrence of the first event to the occurrence of the second event is within the set range (S23; Yes), the determination unit 306a of the radiation detector 1c The event information of the first event is discarded based on the determination result, the discard information for discarding the second event is generated, and the second event occurs via the second communication unit 310 and the communication line 311 (S24).

  When the discard information is input, the discard unit 306c of the radiation detector in which the second event has occurred discards the event information of the second event (S25).

  Here, in step 22, when the second event does not exist within the proximity range of the first event (S22; No), the determination unit 306a of the radiation detector 1c has the data buffer 307, the control unit 308, and the first event. The event information of the first event is output to the total radiation detection circuit 100 via the communication unit 309 (S26).

  In Step 23, when the time interval from the occurrence of the first event to the occurrence of the second event is longer than the set range (S23; No), the determination unit 306a of the radiation detector 1c executes Step 26. To do.

  Note that the discarding unit 306c of one radiation detector may stop outputting the event information of the first event (third event) determined to be a simultaneous event. That is, by stopping the output of event information, the amount of information output from one radiation detector can be suppressed.

  In addition, the determination unit 306a of the other radiation detector acquires the event information of the first event from the one radiation detector via the second communication unit 310 of the other radiation detector, and acquires the acquired first information. Even if the simultaneous event is determined based on the event information of the event and the discarding unit 306c of the other radiation detector stops outputting the event information of the second event (fourth event) determined to be the simultaneous event good. That is, by stopping the output of event information, the amount of information output from other radiation detectors can be suppressed.

(Effect of the second embodiment)
According to the radiation detector 1 according to the second embodiment, the event information of the simultaneous event between the radiation detectors can be discarded before the event information is output to the integrated radiation detection circuit 100. Compared with a detector that does not determine simultaneous events in between, the amount of information to be output is small, and the processing speed of the integrated radiation detection circuit 100 is improved.

  In the above embodiment, as a method for discarding event information, a method for discarding event information of an event to be discarded from the storage unit has been described. A method of adding a flag that does not output the target event information may be used.

  Although the embodiments of the present invention have been described above, the embodiments and modifications described above do not limit the invention according to the claims. In addition, it should be noted that not all the combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

DESCRIPTION OF SYMBOLS 1, 1a-1e ... Radiation detector 3 ... Electronic component mounting part 4 ... Radiation 5 ... Radiation detection apparatus 5a ... Radiation detector stand 10 ... CdTe element 11 ... Substrate 12 ... Flexible substrate 13 ... Card holder 14 ... Card holder 15 ... Elastic member mounting part 16 ... Elastic member 17 ... Protrusion part 18 ... Grooved hole 19 ... Protrusion part 20 to 23 ... Board terminal 29 ... Card edge part 29a ... Pattern 30 ... Radiation detection circuit 50 ... Support plate 51 ... Support body 52 ... Connector 100 ... Total radiation detection circuit 101 ... Communication unit 102 ... Total event determination unit 102a ... Determination unit 102b ... Storage unit 102c ... Discarding unit 103 ... Data buffer 120 to 123 ... Connection unit 300 ... Capacitor 301 ... Preamplifier 302 ... Shaping amplifier 303 ... Peak hold 304 ... A / D converter 305 ... Trigger generator 306 ... Event format Unit 306a ... Determination unit 306b ... Storage unit 306c ... Discarding unit 307 ... Data buffer 308 ... Control unit 309 ... First communication unit 310 ... Second communication unit 311 ... Communication line 510 ... Wall unit 511 ... Groove 512 ... Indentation unit 513: Flat surface

Claims (9)

A semiconductor element having a plurality of detection regions for detecting radiation on an incident surface on which the radiation is incident;
A first storage unit that stores, as event information, position information of a detection region on which the radiation is incident and time information of the incident time;
In a first event in which radiation enters the first detection region of the semiconductor element and a second event in which radiation enters the second detection region of the semiconductor element, the first event and the second event When a time interval with an event is shorter than a predetermined time interval, a first determination unit that determines the first event and the second event as simultaneous events;
A first discarding unit that discards the first event information of the first event determined as the simultaneous event and the second event information of the second event from the first storage unit;
Radiation detector equipped with.   The first determination unit is configured such that a time interval between the first event and the second event is shorter than a predetermined time interval, and from the first detection region to the second detection region. The radiation detector according to claim 1, wherein when the distance is within a predetermined range, the first event and the second event are determined as simultaneous events.   The predetermined range is an 8-connected detection region based on a detection region on which the radiation is incident, or a detection region around the 8-connected detection region and the 8-connected detection region. The radiation detector according to 2. A plurality of radiation detectors according to any one of claims 1 to 3,
One radiation detector of the plurality of radiation detectors has the first detection region, and the other radiation detector has the second detection region,
A second determination unit that determines the simultaneous event based on event information output from the one radiation detector and the other radiation detector;
A radiation detection apparatus comprising: A second storage for storing the first event information and the second event information;
Discarding the first event information determined by the second determination unit as the simultaneous event, the first event information of the second event, and the second event information from the second storage unit; Two discarding units;
The radiation detection apparatus according to claim 4, comprising: The plurality of radiation detectors according to any one of claims 1 to 3, each having a mutual communication unit, connected to each other,
When a third event occurs in one radiation detector of the plurality of radiation detectors and a fourth event occurs in another radiation detector of the plurality of radiation detectors,
The first determination unit of the one radiation detector acquires event information of the fourth event from the other radiation detector via the mutual communication unit of the first radiation detector, and the acquired A radiation detection apparatus that determines the simultaneous event based on event information of a fourth event.   The first discard unit of the one radiation detector discards the event information of the third event determined as the simultaneous event, and further generates the discard information for discarding the event information of the fourth event And the radiation detection apparatus of Claim 6 which outputs to said other radiation detector via the said mutual communication part.   The radiation detection apparatus according to claim 6, wherein the first discarding unit of the one radiation detector stops outputting event information of the third event determined as the simultaneous event. The first determination unit of the other radiation detector acquires event information of the third event from the one radiation detector via the mutual communication unit of the other radiation detector, and the acquired first event is acquired. The simultaneous event is determined based on event information of event 3,
The radiation detection apparatus according to claim 6, wherein the first discarding unit of the other radiation detector stops outputting event information of the fourth event determined to be the simultaneous event.

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