JPWO2009054233A1 - Radiation detector - Google Patents

Abstract

The radiation detector 1 of the present invention includes a pulse width modulation circuit 11 that binarizes an analog electric pulse P output from a detection cell 7 with a predetermined threshold value Vth and modulates it into a digital electric pulse Pp, and radiation is incident thereon. Since the data superimposing unit 13 that superimposes the incident position pulses Px and Py related to the position of the detection cell 7 and the digital electric pulse Pp detected by radiation and outputs the incident position pulse train Pt is provided, the output of the conventional digital electric pulse Pp is provided. Can be added to the digital electric pulse Pp. Therefore, the position of the radiation incident on the detection cell 7 can be detected in a shorter time compared to the prior art in which the position information is transmitted after the digital electric pulse Pp is transmitted.

Description

  The present invention relates to a radiation detector including a plurality of detection cells that detect incident radiation by converting incident radiation into electric pulses, and more particularly to a technique for detecting the position of a detection cell on which radiation is incident.

  As a conventional technique, a detector for PET (Positron Emission Tomography) which is a radiation detector will be described as an example. As a PET detector, a radiation detector in which small-area detection cells are arranged at a pitch of about 1 mm has been proposed for the purpose of improving spatial resolution. In order to secure an effective visual field size using such a small-pitch detection cell, it is necessary to arrange the detection cells two-dimensionally, resulting in an enormous number of channels.

In general, there are two types of methods for identifying which detection cell of many detection cells is irradiated with radiation. The first is a method of reading all signals obtained from the channels in parallel (see, for example, Patent Document 1). The second is a method that is realized by calculating the center of gravity using an analog circuit called an anger method (see, for example, Patent Document 2). Conventionally, since it is necessary to reduce the cost of a circuit unit in a commercial machine, an anger method using a PMT (photomultiplier tube) is used.
JP-A-8-68863 (page 2-3, FIG. 1) JP-A-7-311270 (page 2-3, FIG. 2, FIG. 4)

  However, the conventional technique has the following problems. That is, in order to achieve a spatial resolution of 1 mm or less, the number of signal wirings increases and the number of signal wirings increases, so that the signals are easily affected by noise and it is difficult to obtain a predetermined spatial resolution and temporal resolution. .

  The present invention has been made in view of such circumstances, and can detect the position of radiation incident on a detection cell in a short time even when detecting radiation with a large number of detection cells. The purpose is to provide.

In order to achieve such an object, the present invention has the following configuration.
That is, the radiation detector of the present invention is a radiation detector including a plurality of detection cells that detect incident radiation by converting incident radiation into analog electrical pulses, and the analog electrical pulses are binarized at a predetermined threshold value. And a pulse width modulation means for outputting a digital electric pulse and a position information adding means for outputting an incident position pulse train obtained by adding information on the position of a detection cell on which radiation is incident to the electric pulse. Is.

  As a result, the pulse width modulation means binarizes the analog electric pulse output from the detection cell with a predetermined threshold value and modulates it into a digital electric pulse, and the position information addition means detects the position of the detection cell where the radiation is incident. Since the incident position pulse train is output by superimposing the information on the information and the electric pulse detected by the incidence of the radiation, the position information added after the output of the conventional electric pulse can be added to the electric pulse. . Therefore, the position of the radiation incident on the detection cell can be detected in a shorter time compared to the prior art in which the position information is transmitted after the electrical pulse is added.

  According to the present invention described above, it is preferable that the position information adding means outputs the incident position pulse train in synchronization with a timing when the analog electric pulse exceeds and falls below a predetermined threshold value. As a result, the position information adding means outputs the incident position pulse train in synchronization with the timing when the analog electric pulse exceeds and falls below the predetermined threshold value. Therefore, based on the change in the magnitude of the analog electric pulse, the detection cell The position of the radiation incident on can be detected in a short time.

  According to the present invention described above, it is preferable that the width of each pulse constituting the incident position pulse train is the X channel number and the Y channel number of the detection cells arranged two-dimensionally in the X direction and the Y direction. . As a result, the X channel number and Y channel number of the detection cell to which the radiation is incident can be accurately detected, so that the position in the X direction and the Y direction of the detection cell to which the radiation is incident can be detected in a short time.

  According to the present invention described above, the width of each pulse constituting the incident position pulse train has the X channel number, Y channel number, and Z of the detection cells arranged in three dimensions consisting of the X direction, the Y direction, and the Z direction. A channel number is preferred. This makes it possible to accurately detect the X channel number, Y channel number, and Z channel number of the detection cell to which the radiation is incident, so that the X, Y, and Z direction positions of the detection cell to which the radiation is incident can be detected in a short time. it can.

  According to the present invention described above, the pitch of each pulse constituting the incident position pulse train is preferably proportional to the peak value of the analog electric pulse. As a result, since the pitch of each pulse constituting the incident position pulse train is proportional to the peak value of the analog electric pulse, the peak value of the radiation incident on the detection cell can be detected in a short time based on the pitch of each pulse. Can do.

  According to the present invention described above, it is preferable to include pulse train compression means for compressing the incident position pulse train and outputting a compressed pulse train, and pulse train restoration means for restoring the compressed pulse train to the incident position pulse train. Thus, the pulse train compression means compresses the incident position pulse train output for each detection cell and outputs a compressed pulse train, and the pulse train restoration means restores the transmitted incident position pulse train, so that the number is smaller than the number of detection cells. The incident position pulse train can be transmitted through the transmission line.

  According to the present invention described above, the pulse train compression means is provided for each group composed of a plurality of the detection cells, and the compressed pulse train is output for each group and output for each group. It is preferable to further comprise group position information adding means for outputting, for each group, a group pulse train obtained by adding information related to the position of the group. As a result, the group position information adding means adds the group position information to the compressed pulse train and outputs the group pulse train. Therefore, even in the radiation detector having the detection cells grouped for each group, the group pulse train output from each group Can be detected with a small number of transmission lines.

  According to the present invention described above, group compression means for compressing the group pulse train and outputting a group compressed pulse train, and group restoration for restoring the group compressed pulse train to the group pulse train and restoring the group pulse train to the compressed pulse train Means. Thus, the group compression means compresses the group pulse train output from the group position information adding means and outputs a group compressed pulse train, and the group decompression means restores the group compressed pulse train to the original group pulse train. Even when the compressed pulse train is output from the pulse train compressing means provided in, the position of the group from which the compressed pulse train is output can be detected in a short time.

  According to the present invention described above, the position information adding means includes a delay circuit (B) that outputs a delay signal (A) that is output corresponding to information on the position of the detection cell, the electrical pulse, and the delay. It is preferable to include a logic circuit (C) that outputs the incident position pulse train when the signal (A) is input. As a result, the position information adding means includes a delay circuit (B) and a logic circuit (C), and the delay circuit (B) outputs a delay signal (A) corresponding to information on the position of the detection cell. C) outputs an incident position pulse train when an electric pulse and a delay signal (A) are input, so that the position information adding means outputs an incident position pulse train corresponding to information on the position of the detection cell on which the radiation is incident. Can do. Therefore, the position of the radiation incident on the detection cell can be detected in a short time.

  According to the above-described present invention, the logic circuit (C) has another pulse that constitutes the incident position pulse train, in which one pulse constituting the incident position pulse train falls in synchronization with the rise of the delay signal (A). It is preferable that the pulse is a logic circuit that falls in synchronization with the fall of the delay signal (A) and outputs the incident position pulse train by superimposing the one pulse and the other pulse in a row. Thereby, the incident position pulse train includes time information from the rise of the digital electric pulse to the rise of the delay signal (A), and time information from the fall of the digital electric pulse to the fall of the delay signal (A). Are superimposed. Therefore, the position of the radiation at which the digital electric pulse enters the detection cell can be detected in a short time based on the time information.

  According to the above-described present invention, the position information adding means includes a capacitor having a capacitance corresponding to information on the position of the detection cell and a resistor having a resistance value, and outputs a delay signal (D). (E), a comparator that outputs each pulse constituting the incident position pulse train when the delay signal (D) exceeds a predetermined threshold compared with a predetermined threshold, and is output from the comparator And a logic circuit (F) for outputting the incident position pulse train by superimposing the pulses to be arranged in a row. Thereby, the capacitor and the resistor constituting the delay circuit (E) change the output of the electric pulse, and the comparator binarizes when the electric pulse output through the capacitor and the resistor exceeds a predetermined threshold value. Since each pulse constituting the incident position pulse train is output and the logic circuit (F) bundles each pulse output from the comparator, the position information adding means corresponds to the incident position corresponding to information on the position of the detection cell on which the radiation is incident. A pulse train can be output. Therefore, the position of the radiation incident on the detection cell can be detected in a short time.

  According to the present invention described above, the group position information adding means includes a delay circuit (H) that outputs a delay signal (G) that is output corresponding to information on the position of the group, the compressed pulse train, and the delay. It is preferable to include a logic circuit (I) that outputs the group pulse train when a signal (G) is input. Thereby, the group position information adding means includes a delay circuit (H) and a logic circuit (I), and the delay circuit (H) outputs a delay signal (G) corresponding to information on the position of the group. I) outputs a group pulse train when a compressed pulse train and a delay signal (G) are inputted, so that the group position information adding means outputs a group pulse train corresponding to information on the position of the group from which the compressed pulse train is outputted. Can do. Therefore, the position of the group from which the compressed pulse train is output can be detected in a short time.

  According to the present invention described above, the logic circuit (I) is configured such that one pulse constituting the group pulse train falls in synchronization with the rise of the delay signal (G), and another pulse constituting the group pulse train. Is a logic circuit that falls in synchronization with the fall of the delay signal (G) and outputs the group pulse train by superimposing the one pulse and the other pulse in a row. Thereby, the position of the group from which the compressed pulse train is output can be detected in a short time.

  According to the above-described present invention, the group position information adding means includes a capacitor having a capacity corresponding to information on the position of the group and a resistor having a resistance value, and outputs a delay signal (J). (K), a comparator (L) for outputting each pulse constituting the group pulse train when the delay signal (J) exceeds a predetermined threshold value compared with a predetermined threshold value, and the comparator It is preferable to include a logic circuit (M) that outputs the group pulse train by superimposing the pulses output from (L) in a row. As a result, the capacitor and resistor constituting the delay circuit (J) change the output of the compressed pulse train, and the comparator (L) outputs two signals when the compressed pulse train output through the capacitor and resistor exceeds a predetermined threshold value. Since each pulse constituting the group pulse train is output as a value, and the logic circuit (M) bundles the group pulse trains output from the comparator (L), the group position information adding means outputs the position of the group from which the compressed pulse train is output. The group pulse train corresponding to the information on can be output. Therefore, the position of the group from which the compressed pulse train is output can be detected in a short time.

  According to the present invention described above, the pulse width modulation means is composed of a plurality of comparators, and each of the comparators is used to binarize the analog electric pulse with a predetermined threshold value to obtain a digital signal. It is preferable to output each electric pulse. Thereby, more accurate peak value and timing information can be obtained.

  According to the present invention described above, it is preferable that the position information adding unit outputs the incident position pulse train by using a multi-value logic method having different pulse widths and pulse amplitudes. Thereby, each pulse is subjected to analog addition, and an incident position pulse train having a different pulse width and pulse amplitude can be output.

  According to the radiation detector of the present invention, the pulse width modulation means binarizes the analog electric pulse output from the detection cell with a predetermined threshold value and modulates it into a digital electric pulse, and the position information adding means is Since the incident position pulse train is output by superimposing the information on the position of the detection cell where the radiation is incident and the electric pulse detected by the incidence of the radiation, the position information added after the output of the conventional electric pulse is used as the electric pulse. Can be added inside. Therefore, the position of the radiation incident on the detection cell can be detected in a shorter time compared to the prior art in which the position information is transmitted after the electrical pulse is added.

1 is a block diagram illustrating an overall configuration of a radiation detector according to Embodiment 1. FIG. 3 is a timing chart illustrating signal addition in the radiation detector according to the first embodiment. FIG. 3 is a circuit diagram of a data superimposing device provided in the radiation detector according to the first embodiment. It is a schematic diagram which shows the information content which can be expressed with the data superimposer with which the radiation detector which concerns on Example 1 is equipped. 3 is a schematic diagram of a detection cell group provided in the radiation detector according to Embodiment 1. FIG. 10 is a timing chart illustrating signal addition in the radiation detector according to the second embodiment. 6 is a circuit diagram of a CR data superimposing device provided in a radiation detector according to Embodiment 2. FIG. FIG. 6 is a block diagram illustrating an overall configuration of a radiation detector according to a third embodiment. 6 is a schematic diagram of a detector block provided in a radiation detector according to Embodiment 3. FIG. FIG. 10 is a circuit diagram of a pulse width modulation circuit and a data superimposer provided in the radiation detector according to the fourth embodiment. 10 is a timing chart of a pulse width modulation circuit and a data superimposer according to the fourth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Radiation detector 7 ... Detection cell 11 ... Pulse width modulation circuit 13 ... Data superimposer 17 ... Compressor P ... Analog electric pulse Pp ... Digital electric pulse Px ... Incident position pulse Py which shows X channel number of detection cell Py ... Detection Incidence position pulse indicating cell Y channel number Pw ... Pp pulse width Pw1 ... Px pulse width Pw2 ... Py pulse width Pw3 ... Rise time difference between Px and Py Pt ... Incident position pulse train Pp1 ... Digital electric pulse Pp2 ... Digital electric Pulse Pp3 ... Digital electric pulse Pp4 ... Digital electric pulse Pw4 ... Pp1 pulse width Pw5 ... Pp2 pulse width Pw6 ... Pp3 pulse width Pw7 ... Pp4 pulse width Pw8 ... Px pulse width Pw9 ... Py pulse width Pt2 ... Pp3 And Pp Incident position pulse train having a Pt3 ... (the multi-valued logic) incident position pulse train

  The position of the radiation incident on the detection cell is accurately detected in a short time by superimposing the information on the position of the detection cell on which the radiation is incident and the electrical pulse detected by the incidence of the radiation and outputting an incident position pulse train. The purpose was realized.

  Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating the overall configuration of the radiation detector according to the first embodiment. FIG. 2 is a timing chart for generating an incident position pulse train by adding a delay signal to the electrical pulse detected by the radiation detector. 3 is a circuit diagram of a data superimposing unit that generates the incident position pulse train, FIG. 4 is a schematic diagram showing the number of channels that can be represented by the data superimposing unit, and FIG. 5 is a plurality of detection cells. 7 is a diagram showing detection cell groups arranged two-dimensionally in the X direction and the Y direction.

As shown in FIG. 1, the radiation detector 1 according to the first embodiment includes detection cells 7 ₁ to 7 ₆₄ each having a scintillator 3 and a photomultiplier tube 5 (hereinafter collectively referred to as a detection cell 7). And preamplifiers 9 ₁ to 9 ₆₄ (hereinafter collectively referred to as preamplifier 9) for amplifying the analog electric pulse P detected by the detection cell 7, a pulse width modulation circuit 11 and a data superimposer. provided no metadata adders 15 ₁ and a 13 to 15 64 _(hereinafter collectively metadata adder 15) and, a compressor 17 for compressing the incident position pulse train Pt outputted from the metadata addition unit 15 . The compressed pulse train output from the compressor 17 is restored to the original incident position pulse train Pt by the decompressor 19. The incident position pulse train Pt is output to the position calculation circuit 21, and the position calculation circuit 21 calculates the position where radiation enters the detection cell from the incident position pulse train Pt.

  The radiation detector 1 is a radiation detector or a semiconductor detector in which a scintillator 3 and a photomultiplier tube (PMT: PhotoMultiplier Tube) (5), an APD (Avalache Photo Diode), or a SiPM (Silicon PhotoMultiplier).

As shown in FIG. 5, the detection cells 7 are two-dimensionally arranged in the X direction and the Y direction to constitute a detection cell group 8. In the detection cell group 8, eight detection cells 7 are arranged in the X direction, and eight detection cells 7 are arranged in the Y direction. That is, the detection cell 7 has channel numbers x1 to x8 in the X direction and channel numbers y1 to y8 in the Y direction. Each detection cell 7 has channel information such as a detection cell 7 ₁ (x = 1, y = 1) and a detection cell 7 ₂ (x = 2, y = 1). Detection cell group 8 is provided with a detection cell 7 to the detection cell _{7 1-7 64.}

  The pulse width modulation circuit 11 will be described with reference to FIGS. As shown in FIG. 1, the pulse width modulation circuit 11 modulates the analog electric pulse P input from the preamplifier 9 into a digital electric pulse Pp and outputs it to the data superimposer 13. The pulse width modulation circuit 11 compares the analog electric pulse P input from the detection cell 7 with the threshold voltage Vth, and outputs High when the analog electric pulse P exceeds the threshold voltage Vth. When P is lower than the threshold voltage Vth, Low is output. Note that the output Pp of the pulse width modulation circuit 11 corresponds to In in FIG. At this time, as shown in FIG. 2, as the time T during which the voltage value of the analog electric pulse P exceeds the threshold voltage Vth is longer, the digital electric pulse Pp output from the pulse width modulation circuit 11 (In shown in FIG. 2). The width Pw of the output high becomes longer. Conversely, the shorter the time T during which the voltage value of the analog electric pulse P exceeds the threshold voltage Vth, the shorter the width Pw of the output High of the digital electric pulse Pp output from the Halth width modulation circuit 11. Further, the width Pw becomes longer as the signal intensity (voltage value) of the analog electric pulse P is larger, and the width Pw becomes shorter as the signal intensity (voltage value) of the analog electric pulse P is smaller. That is, the pulse width modulation circuit 11 encodes the signal intensity of the analog electric pulse P into the pulse width Pw. The pulse width modulation circuit 11 corresponds to the pulse width modulation means of this invention.

A circuit provided in the data superimposing unit 13 will be described with reference to FIG. The pulse width modulation circuit 11 outputs the digital electric pulse Pp to the delay generator 23 and the NOT circuit 25. The NOT circuit 25 outputs the digital electric pulse Pp to the NOR circuit 27 and the AND circuit 29. On the other hand, the delay generator 23 outputs a delay signal Dx corresponding to any X channel number of the detection cells 7 ₁ to 7 ₆₄ to which the analog electric pulse P is output to the NOR circuit 27, and the analog electric pulse P is output. The delayed signal Dy corresponding to any Y channel number of the detected cells 7 ₁ to 7 ₆₄ is output to the AND circuit 29. The delay generator 23 is a shift register circuit using, for example, a D flip-flop. The analog electric pulse P here refers to a pulse before the digital electric pulse Pp is binarized. The NOR circuit 27 outputs the incident position pulse Px corresponding to the X channel number to the OR circuit 31, and the AND circuit 29 outputs the incident position pulse Py corresponding to the Y channel number to the OR circuit 31. The OR circuit 31 outputs an incident position pulse train Pt to the compressor 17 based on the incident position pulses Px and Py. The data superimposer 13 corresponds to the position information adding means of the present invention. The delay signals Dx and Dy correspond to the delay signal (A) of the present invention, the delay generator 23 corresponds to the delay circuit (B) of the present invention, the NOT circuit 25, the NOR circuit 27, the AND circuit 29 and the OR. The circuit 31 corresponds to the logic circuit (C) of the present invention.

  The timing for adding position information to the digital electric pulse will be described with reference to FIG. FIG. 2 is a timing chart in which the vertical axis represents signal values and the horizontal axis represents time. In is a digital electric pulse Pp output from the pulse width modulation circuit 11. In bar is a signal output from the NOT circuit 25. D 1, D 2, D 3, Dx, and Dy are delay signals output from the delay generator 23. Out is an incident position pulse train Pt composed of incident position pulses Px and Py. Pw1 indicates the pulse width when the incident position pulse Px is High. Pw2 indicates the pulse width when the incident position pulse Py is High. Pw3 indicates a time difference from the rising of the incident position pulse Px to the rising of the incident position pulse Py. The delay signals D1, D2, and D3 correspond to the delay signal (A) of the present invention.

  The incident position pulse Px rises in synchronization with the rise of In (Pp) and falls in synchronization with the rise of the delay signal Dx. The incident position pulse Py rises in synchronization with the fall of In (Pp), and falls in synchronization with the fall of the delay signal Dy.

  As described above, the pulse width Pw1 of the incident position pulse Px and the pulse width Pw2 of the incident position pulse Py constituting the incident position pulse train Pt are the X channel number and Y channel number of the detection cell 7 from which the analog electric pulse P is output. means. Since Pw3 indicating the rise time difference between the incident position pulse Px and the incident position pulse Py constituting the incident position pulse train Pt varies depending on the magnitude of the analog electric pulse P, it means the peak value H of the analog electric pulse P. The rising of the incident position pulse train Pt or the incident position pulse Px means the timing at which radiation enters the detection cell 7.

With reference to FIG. 4, the number of channels of the detection cell 7 on which the incident position pulse train Pt can be superimposed will be described. Here, the number of channels means the number of detection cells 7 represented as detection cells 7 ₁ to 7 ₆₄ shown in FIG.

  The number of channels of the detection cell 7 that can be superimposed on the incident position pulse train Pt is the product of the number of channels in the X direction and the number of channels in the Y direction that can be expressed by the incident position pulses Px and Py. The number of channels in the X direction of the detection cell 7 that can express the incident position pulse Px is the minimum value of the peak value of radiation that needs to be measured (minimum value of the pulse width Pw1), that is, the rise time difference between Px and Py (hereinafter referred to as pulse). This is the number obtained by dividing Pw3 by the readout time resolution Tr of the decompressor 19. If the entire pulse width Pw1 is used for the channel information, the boundary between the pulse width Pw1 and the pulse width Pw2 cannot be determined. Therefore, it is preferable to separate by at least 1Tr. Expressing the number of channels in the X direction as X, X = Pw3 ÷ Tr−1. Similarly, when the number of channels in the Y direction is expressed as Y, Y = Pw2 ÷ Tr−1. The obtained product of X and Y is the number of detection cell channels that can be expressed by the pulse widths Pw1 and Pw2.

  More specifically, as shown in FIG. 4, X and Y depend on the minimum pulse width Pw1min generated in each channel, the required maximum count rate CRmax, and the time resolution Tr of the subsequent readout method, and X = Pw1min / Tr-1 and Y = (1 / CRmax-Pw1max) / Tr-1. Pw1max is the maximum value of the pulse width Pw1 of the incident position pulse Px. This is the same value as the pulse pitch Pw3. CRmax is the maximum count rate required for the radiation detector. 1 / CRmax is the minimum time until the next incidence of radiation. Tr is the readout time resolution of the decompressor 19.

  For example, when the time resolution of the reading means is 10 ns, the pulse width of the pulse Pp1 generated in each channel when an event is incident is 100 to 200 ns, and the required maximum count rate is 4 Mcps, X = 100 ns ÷ 10 ns-1 = 9 , Y is (250 ns−200 ns) ÷ 10 ns−1 = 4, and the number of pieces of information that can be expressed under this condition is X × Y = 9 × 4 = 36. This is an insufficient number in a large-scale system, but if the time resolution Tr is improved, the number of information that can be dramatically expressed can be increased. For example, when Tr is 5 ns, X × Y = 171, and when Tr is 2 ns, X × Y = 1176. If the time resolution of the reading unit is about 2 ns, the number of channels exceeding 1000 ch can be expressed. Alternatively, the number of channels that can be expressed can be increased by adding pulses to the subsequent stage as a pulse train.

  The compressor 17 compresses the incident position pulse train Pt output from each detection cell 7 and outputs the compressed pulse train Pc to the decompressor 19. The decompressor 19 restores the compressed pulse train Pc to the original incident position pulse train Pt. The compressor 17 corresponds to the pulse train compression means of the present invention, and the decompressor 19 corresponds to the pulse train decompression means of the present invention.

  According to the radiation detector 1 described in the first embodiment, the pulse width modulation circuit 11 binarizes the analog electric pulse P output from the detection cell 7 with the predetermined threshold value Vth and modulates the digital electric pulse Pp, Since the data superimposing unit 13 superimposes the incident position pulses Px and Py related to the position of the detection cell 7 on which the radiation is incident and the digital electric pulse Pp detected by the radiation to output the incident position pulse train Pt, the conventional digital electric pulse Pp The position information added after the output can be added to the digital electric pulse Pp. Therefore, the position of the radiation incident on the detection cell 7 can be detected in a shorter time compared to the prior art in which the position information is transmitted after the digital electric pulse Pp is transmitted.

  According to the radiation detector 1 described in the first embodiment, the data superimposing unit 13 includes the incident position pulse Px constituting the incident position pulse train Pt in synchronization with the timing when the analog electric pulse P exceeds and falls below the predetermined threshold value Vth. , Py are output, the incident position pulse train Pt can be output in accordance with the change in the magnitude of the analog electric pulse Pp. Therefore, the peak value of the radiation incident on the detection cell 7 can be detected in a short time based on the change in the pulse pitch of the incident position pulse train Pt.

  According to the radiation detector 1 described in the first embodiment, the pulse width Pw1 when the incident position pulse Px constituting the incident position pulse train Pt is High, and the pulse width Pw2 when the incident position pulse Py is High are X Since the X channel number and the Y channel number of the detection cells 7 arranged in two dimensions composed of the direction and the Y direction, the X channel number and the Y channel number of the detection cell 7 on which the radiation is incident can be accurately detected. Since the data superimposing unit 13 superimposes the incident position pulse Px having the pulse width Pw1 and the incident position pulse Py having the pulse width Pw2 on the digital electric pulse Pp and outputs the incident position pulse train Pt, the detection cell 7 to which the radiation enters is detected. Can be detected in a short time.

  According to the radiation detector 1 described in the first embodiment, the width of each pulse constituting the incident position pulse train Pt is the X channel number of the detection cells 7 arranged in the three dimensions of the X direction, the Y direction, and the Z direction. Since the Y channel number and the Z channel number are used, the X channel number, the Y channel number, and the Z channel number of the detection cell 7 on which the radiation is incident can be accurately detected. Therefore, the positions in the X direction, the Y direction, and the Z direction of the detection cell 7 on which the radiation enters can be detected in a short time.

  According to the radiation detector 1 described in the first embodiment, since the rise time difference Pw3 between the incident position pulse Px and the incident position pulse Py constituting the incident position pulse train Pt is proportional to the peak value of the analog electric pulse P, the incident position pulse Px. And the rise time difference Pw3 of the incident position pulse Py, the position and peak value of the radiation incident on the detection cell 7 can be detected in a short time.

  According to the radiation detector 1 described in the first embodiment, the compressor 17 compresses the incident position pulse train Pt output for each detection cell 7 and outputs the compressed pulse train Pc, and the decompressor 19 applies the compressed pulse train Pc to the incident position. Since the pulse train Pt can be restored, the position of the radiation incident on the detection cell 7 can be detected in a short time. Further, the number of transmission lines from the compressor 17 to the decompressor 19 can be reduced as compared with the prior art.

  According to the radiation detector 1 described in the first embodiment, the data superimposing unit 13 includes the delay generator 23, the NOT circuit 25, the NOR circuit 27, and the AND circuit 29. When radiation enters the detection cell 7, the delay generator 23 outputs a delay signal Dx corresponding to the X channel number unique to the detection cell 7 to the NOR circuit 27 based on the digital electric pulse Pp detected by the detection cell 7. The delay signal Dy corresponding to the Y channel number unique to the detection cell 7 is output to the AND circuit 29. The NOT circuit 25 inverts the digital electric pulse Pp detected by the detection cell 7 and outputs it to the NOR circuit 27 and the AND circuit 29. When the NOR circuit 27 receives the inverted digital electric pulse Pp, it raises the input position pulse Px and outputs it to the OR circuit 31. When the delay signal Dx and the inverted digital electric pulse Pp are output to the NOR circuit 27, the NOR circuit 27 lowers the incident position pulse Px and stops the output. On the other hand, the AND circuit 29 does not output the incident position pulse Py even if the inverted digital electric pulse Pp is input, but if the rising edge of the inverted digital electric pulse Pp and the delay signal Dy are input, the AND position 29 The pulse Py is raised and output to the OR circuit 31. Each time the incident position pulses Px and Py are input, the OR circuit 31 outputs the incident position pulses Px and Py as an incident position pulse train Pt. Therefore, the incident position pulses Px and Py have pulse widths Pw1 and Pw2 specific to the detection cell 7, and the incident position pulses Px and Py are superimposed on the digital electric pulse Pp and output as the incident position pulse train Pt. The position of the radiation incident on the cell 7 can be detected in a short time.

  Next, Embodiment 2 of the present invention will be described with reference to the drawings. FIG. 6 is a timing chart for generating an incident position pulse train from an electric pulse detected by the radiation detector according to the second embodiment, and FIG. 7 is a circuit diagram of a CR type data superimposing unit for generating the incident position pulse train. is there.

  The overall configuration of the radiation detector 1 according to the second embodiment is approximately the same as the overall configuration of the radiation detector 1 according to the first embodiment, but a CR data superimposer instead of the data superimposer 13 described in the first embodiment. 51 is different.

  A circuit diagram of the CR data superimposing unit 51 will be described with reference to FIG. The CR data superimposing unit 51 includes a CR circuit including buffer circuits 53A and 53B, capacitors 55A and 55B, resistors 57A and 57B, comparators 59A and 59B, and an OR circuit 61. The capacitors 55A and 55B and the resistors 57A and 57B correspond to the delay circuit (E) of the present invention, and the OR circuit 61 corresponds to the logic circuit (F) of the present invention.

  The digital electric pulse Pp is input from the pulse width modulation circuit 11 to the buffer circuit 53A. Next, the digital electric pulse Pp is input from the buffer circuit 53A to the capacitor 55A. Next, the digital electric pulse Pp is output from the capacitor 55A while being discharged by the resistor 57A. This output is CRoutA. CRoutA is input to the comparator 59A. CRoutA is binarized by the threshold value VthA and input to the OR circuit 61 from the comparator 59A. This binarized output is referred to as an incident position pulse Px. The incident position pulse Px is superimposed on the incident position pulse Py similarly output from the comparator B to form an incident position pulse train Pt. The incident position pulse train Pt is input from the OR circuit 61 to the compressor 17. CRoutA and CRoutB correspond to the delayed signal (D) of the present invention.

  The capacitors 55A and 55B have the same capacity, but the capacity differs for each detector 7 to which the digital electric pulse Pp is output. The correspondence relationship between each detection cell 7 and the capacitances of the capacitors 55A and 55B is stored in a memory (not shown) as a lookup table, for example. Capacitors 55A and 55B having different capacities for each detection cell 7 may be prepared.

  The resistors 57A and 57B have the same configuration as the capacitors 55A and 55B. Each detection cell 7 and the resistance values of the resistors 57A and 57B have a correspondence relationship.

  The timing at which the CR data superimposing unit 51 generates the incident position pulse train Pt from the digital electric pulse Pp detected by the radiation detector 1 will be described with reference to FIG.

  As in the first embodiment, In is a digital electric pulse Pp output from the pulse width modulation circuit 11. CRoutA is a voltage value output to the comparator 59A when the digital electric pulse Pp is input to the CR circuit composed of the capacitor 55A and the resistor 57A. VthA is a threshold voltage that binarizes CRoutA with a positive value. Px is an incident position pulse obtained by binarizing the digital electric pulse Pp. Px is output from the comparator 59A to the OR circuit 61.

  CRoutB is a voltage value output to the comparator 59B when the digital electric pulse Pp is input to the CR circuit composed of the capacitor 55B and the resistor 57B. VthB is a threshold voltage that binarizes CRoutB with a negative value. Py is an incident position pulse obtained by binarizing the digital electric pulse Pp. Py is output from the comparator 59B to the OR circuit 61.

  The pulse widths Pw1 and Pw2 of the incident position pulses Px and Py are different for each detection cell 7. The pulse width Pw1 means the X channel number of the detection cell 7, and the pulse width Pw2 means the Y channel number of the detection cell 7. Also, the rise time difference Pw3 between Px and Py is different for each detection cell 7. The rise time difference Pw3 between Px and Py means the peak value H of the analog electric pulse P detected by the detection cell 7. The rising of the incident position pulse train Pt or the incident position pulse Px means the timing at which radiation enters the detection cell 7.

  The OR circuit 61 outputs the incident position pulse Px as the incident position pulse train Pt each time the incident position pulses Px and Py are input.

  According to the radiation detector 1 according to the second embodiment, when the digital electric pulse Pp is input from each detection cell 7 to the CR data superimposer 51, the capacitor 55A stores electric charge, and a part of the stored electric charge is grounded. The remaining CRoutA is discharged to the comparator 57A. The comparator 57A outputs the incident position pulse Px to the OR circuit 61 while CRoutA exceeds the threshold voltage VthA. On the other hand, the capacitor 55B and the resistor 57B similarly output CRoutB to the comparator 57B. Comparator 57B outputs incident position pulse Py to OR circuit 61 while CRoutB falls below threshold voltage VthB. The OR circuit 61 outputs an incident position pulse train Pt each time the incident position pulses Px and Py are input. The incident position pulses Px and Py have pulse widths Pw1 and Pw2 determined by the capacitances of the capacitors 55A and 55B unique to each detection cell 7 and the resistance values of the resistors 57A and 57B. The incident position pulses Px and Py are incident position pulse train Pt Therefore, the position of the radiation incident on the detection cell 7 can be detected in a short time.

  Next, Embodiment 3 of the present invention will be described with reference to the drawings. FIG. 8 is a block diagram illustrating an overall configuration of a radiation detector that can add group position information to a compressed pulse train when a plurality of detection cells form a group in the radiation detector according to the third embodiment. It is a figure which shows the DOI detector by which the some detection cell 7 is arranged in two dimensions of a X direction, a Y direction, and a Z direction.

A group 71 constituting the DOI detector 70 will be described with reference to FIG. The DOI detector 70 basically has the same configuration as the detection cell group 8 of the first and second embodiments, but the detection cells 7 are arranged in the X direction, the Y direction, and the Z direction, and the groups 71A, 71B, 71C, 71D four-layer structure. Group 71A includes detection cells 7 ₁ through 7 ₆₄ , group 71B includes detection cells 7 ₆₅ through 7 ₁₂₈ , group 71C includes detection cells 7 ₁₂₉ through 7 ₁₉₄ , and group 71D includes detection cells 7 ₁₉₅ through 7 ₂₅₆ . Prepare. Each detection cell has channel information, such as for example detection cell ₇₁ if (x = 1, y = 1 , z = 1), 7 256 if (x = 8, y = 8 , Z = 4).

  With reference to FIG. 8, the whole structure of the radiation detector 1 which concerns on Example 3 is demonstrated. Here, a plurality of detection cells 7 are assembled to form groups 71A to 71D. Note that the detection cell 7, the preamplifier 9, the metadata adder 15, and the compressor 17 included in each group 71 are the same as those in the first and second embodiments, and thus description thereof is omitted. Behind each group 71 is a group address superimposing unit 73 that superimposes a group address on the output from each group 71, a group compressor 75 that compresses each output from the group address superimposing unit 73, and a compressed output. A group restoring unit 77 that restores the output of each group 71. Although not shown in the figure, a restorer 19 for restoring the output for each group to the output for each detection cell is provided behind the group restorer 77.

  Each group 71 is a detector of each layer constituting the DOI detector 70 in which scintillators are arranged in multiple layers for the purpose of obtaining depth of interaction information DOI (depth of interaction) of the scintillator. Further, for example, a block type detector provided in a multiple ring PET (multiple ring PET) in which a large number of block type detectors are arranged on the circumference and a plurality of the block type detectors are arranged in the body axis direction may be used.

  The compressor 17 included in each group 71 outputs a compressed pulse train Pc obtained by compressing the incident position pulse train Pt output from each detection cell 7 to the group address superimposer 73.

  The group address superimposing unit 73 superimposes the position information of each group on the compressed pulse train Pc output from each group 71. The compressed pulse train Pc on which the position information of each group is superimposed is called a group pulse train Pc1. The group address superimposing unit 73 outputs the group pulse train Pc1 to the group compressor 75. The group compressor 75 compresses the group pulse train Pc1 of each group 71. This compressed group pulse train Pc1 is referred to as a group compressed pulse train Pc2. The group compressor 75 outputs the group compression pulse train Pc2 to the group decompressor 77. The group address superimposing unit 73 corresponds to group position information adding means of the present invention, and the group compressor 75 corresponds to group compressing means of the present invention.

  The group decompressor 77 restores the group compressed pulse train Pc2 to the compressed pulse train Pc of each group 71 according to the group dress position information. The group decompressor 77 outputs the decompressed compressed pulse train Pc to the decompressor 17. The decompressor 17 restores the compressed pulse train Pc to the incident position pulse train Pt of each detection cell 7. The group restoring unit 77 corresponds to the group restoring means of the present invention.

  According to the radiation detector 1 according to the third embodiment, the group address superimposing unit 73 adds the positional information for each group 71 to the compressed pulse train Pc to create a group pulse train Pc1. Therefore, in the radiation detector including the groups 71a to 71n composed of the plurality of detection cells 7, the incident position pulse train Pt output from the metadata adder 15 provided in each group 71 is output from which group 71. The position pulse train Pt can be easily detected. As a result, even when radiation is incident on the detection cells 7 constituting the group 71, the position of the detection cell where the radiation is incident can be detected in a short time.

  According to the radiation detector 1 according to the third embodiment, the group compressor 75 compresses the group pulse train Pc1 to create a group compressed pulse train Pc2. Therefore, when the group compressed pulse train Pc2 is input to the group decompressor 77, it is restored to the original compressed pulse train Pc. Therefore, in the radiation detector 1 including the groups 71a to 71n composed of a plurality of detection cells, the position of the group 71 from which the compressed pulse train Pc is output is determined even when the group pulse train Pc1 is output from each of the multiple groups 71. It can be detected in a short time.

  Next, Embodiment 4 of the present invention will be described with reference to the drawings. FIG. 10 is a circuit diagram illustrating configurations of a pulse width modulation circuit and a data superimposing unit when more accurate pulse peak values and timing information are obtained using a plurality of threshold voltages in the radiation detector according to the fourth embodiment. FIG. 11 is a timing chart of the pulse width modulation circuit and the data superimposer according to the fourth embodiment.

  The overall configuration of the radiation detector 1 according to the fourth embodiment is approximately the same as the overall configuration of the radiation detector 1 according to the first embodiment, but the pulse width modulation circuit 11 and the data superimposer 13 described in the first embodiment are used. Instead, the difference is that a pulse width modulation circuit 11 that binarizes with a plurality of threshold voltages and a data superimposing unit 13 using a multi-level logic method are provided.

  A circuit diagram of the pulse width modulation circuit 11 and the data superimposer 13 will be described with reference to FIG. The pulse width modulation circuit 11 includes two comparators 81A and 81B (indicated as “comparator 1” and “comparator 2” in FIG. 10) and an XOR circuit 83 which is an exclusive OR circuit. The pulse width modulation circuit 11 corresponds to the pulse width modulation means of this invention.

  The analog electric pulse P is input to the comparators 81A and 81B. Next, the comparator 81A compares the analog electric pulse P with the threshold voltage Vth1 and outputs a digital electric pulse Pp1, and the comparator 81B compares the analog electric pulse P with the threshold voltage Vth2. The digital electric pulse Pp2 is output. The digital electric pulse Pp1 output from the comparator 81A is input to the XOR circuit 83, and the digital electric pulse Pp2 output from the comparator 81B is input to the XOR circuit 83. The XOR circuit 83 outputs an incident position pulse train Pt2 having pulses Pp3 and Pp4.

  The data superimposing unit 13 includes two D flip-flops 85A and 85B (indicated as “DFF1” and “DFF2” in FIG. 10), two delay units 87A and 87B, an adder 89, and a NOT circuit 91. The NOT circuit 91 may be provided on the pulse width modulation circuit 11. The data superimposer 13 corresponds to the position information adding means of the present invention.

  The digital electric pulse Pp1 output from the comparator 81A is input to the clock input unit of the D flip-flop 85A, and the NOT electric circuit 91 inverts the digital electric pulse Pp2 output from the comparator 81B, and the inverted pulse Is input to the clock input section of the D flip-flop 85B. The D flip-flop 85A outputs an incident position pulse Px from the Q terminal, and the D flip-flop 85B outputs an incident position pulse Py from the Q terminal. The Q terminal output of the D flip-flop 85A is input to the reset unit R of the D flip-flop 85A through the delay unit 87A, and the Q terminal output of the D flip-flop 85B is input to the reset unit of the D flip-flop 85B through the delay unit 87B. Input to R. The incident position pulse train Pt2 output from the XOR circuit 83 and the incident position pulses Px and Py output from the D flip-flops 85A and 85B are input to the adder 89. The adder 89 analog-adds these incident position pulses Pt2, Px, Py and outputs an incident position pulse train Pt3.

  The timing at which the pulse modulation circuit outputs the incident position pulse train Pt2 from the analog electric pulse will be described with reference to FIG. 11, and the timing at which position information is added to the incident position pulse train Pt2. Similar to FIG. 2, FIG. 11 is a timing chart in which the vertical axis represents the signal value and the horizontal axis represents time. Pp1 is a digital electric pulse output from the comparator 81A (indicated as “comparator 1 output” in FIG. 11). Pp2 is a digital electric pulse output from the comparator 81B (indicated as “comparator 2 output” in FIG. 11). Pt2 is an incident position pulse train output from the XOR circuit 83 (indicated as “pulse width modulation output” in FIG. 11). Pp2 bar is an inverted pulse from the NOT circuit 91, and is an inverted signal of the digital electrical pulse Pp2 output from the comparator 81B (indicated as “comparator 2 inverted output” in FIG. 11). The DFF1 output is the incident position pulse Px output from the D flip-flop 85A. The DFF2 output is the incident position pulse Py output from the D flip-flop 85B. Pw4 indicates a pulse width when the digital electric pulse Pp1 (comparator 1 output) is High. Pw5 indicates a pulse width when the digital electric pulse Pp2 (comparator 2 output) is High. Pw6 indicates the pulse width of the pulse Pp3. Pw7 indicates the pulse width of the pulse Pp4. Pw8 indicates the pulse width when the incident position pulse Px is High. Pw9 indicates a pulse width when the incident position pulse Py is High.

  The comparator 85A compares the analog electrical pulse P with the threshold voltage Vth1, and outputs High when the analog electrical pulse P exceeds the threshold voltage Vth1, and the analog electrical pulse P falls below the threshold voltage Vth1. For example, Low is output and the digital electric pulse Pp1 is output. The comparator 85B compares the analog electrical pulse P with the threshold voltage Vth2, and outputs High when the analog electrical pulse P exceeds the threshold voltage Vth2, and the analog electrical pulse P falls below the threshold voltage Vth2. If it is low, a digital electric pulse Pp2 is output. At this time, as shown in FIG. 11, the longer the time during which the voltage value of the analog electric pulse P exceeds the threshold voltage Vth1, the longer the digital electric pulse Pp1 output from the comparator 85A (the output of the comparator 1 shown in FIG. 11). ) Output high width Pw4 becomes longer, and the longer the time period during which the voltage value of the analog electric pulse P exceeds the threshold voltage Vth2, the more the digital electric pulse Pp2 output from the comparator 85B (the comparator 2 shown in FIG. 11). Output) output high width Pw5 also becomes longer. Conversely, as the time during which the voltage value of the analog electric pulse P exceeds the threshold voltage Vth1 is shorter, the output High width Pw4 of the digital electric pulse Pp1 output from the comparator 85A becomes shorter, and the voltage value of the analog electric pulse P is reduced. Is shorter than the threshold voltage Vth2, the width Pw5 of the output High of the digital electric pulse Pp2 output from the comparator 85B is also shortened. Further, the widths Pw4 and Pw5 become longer as the signal intensity (voltage value) of the analog electric pulse P is larger, and the widths Pw4 and Pw5 become shorter as the signal intensity (voltage value) of the analog electric pulse P is smaller. That is, the comparator 85A encodes the signal strength of the analog electric pulse P into the pulse width Pw4, and the comparator 85B encodes the signal strength of the analog electric pulse P into the pulse width Pw5.

  The XOR circuit 83 performs an exclusive OR operation on the digital electric pulses Pp1 and Pp2 output from the comparators 81A and 81B, respectively, and outputs an incident position pulse train Pt2. That is, when both the digital electric pulses Pp1 and Pp2 are High and Low, the incident position pulse train Pt2 is output Low, and when one of the digital electric pulses Pp1 and Pp2 is High and the other is Low, the incident position pulse train Pt2 Is output to High. In FIG. 11, when the digital electric pulse Pp1 is High and the digital electric pulse Pp2 is Low, the pulse Pp3 is output until the rising edge of the digital electric pulse Pp2, and the pulse Pp4 is output from the falling edge of the digital electric pulse Pp2. . Since threshold voltage Vth2> threshold voltage Vth1, when the voltage value of analog electric pulse P exceeds threshold voltage Vth2, it is always higher than threshold voltage Vth1. Therefore, when the digital electric pulse Pp2 is high, which is also the time during which the voltage value of the analog electric pulse P exceeds the threshold voltage Vth2, even when the voltage value of the analog electric pulse P exceeds the threshold voltage Vth1 A certain digital electric pulse Pp1 is also always High.

  The interval from the rise of the pulse Pp3 to the fall of the pulse Pp4 is the pulse width Pw4, and the interval from the fall of the pulse Pp3 to the rise of the pulse Pp4 is the pulse width Pw5. As described above, the pulse width of the pulse Pp3 is Pw6, and the pulse width of the pulse Pp4 is Pw7. Further, the widths Pw6 and Pw7 are shortened as the signal intensity (voltage value) of the analog electric pulse P is increased. That is, the XOR circuit 83 encodes the signal strength of the analog electric pulse P into the pulse widths Pw6 and Pw7. As described above, the pulse width modulation circuit 11 including the two comparators 81A and 81B and the XOR circuit 83 encodes the signal intensity of the analog electric pulse P into the pulse widths Pw4, Pw5, Pw6, and Pw7.

  The Q terminal of the D flip-flop 85A rises in synchronization with the rising of the digital electric pulse Pp1 output from the comparator 81A to High, resets and falls after the delay time Dx of the delay device 87A has elapsed, and the pulse width An incident position pulse Px having Pw8 (DFF1 output in FIG. 11) is output. The Q terminal of the D flip-flop 85B rises in synchronization with the rise of the Pp2 bar output from the comparator 81B and inverted by the NOT circuit 91 (that is, the fall of the pulse Pp2), and the delay time Dy of the delay device 87B has elapsed. After resetting and falling, an incident position pulse Py having a pulse width Pw9 (output DFF2 in FIG. 11) is output. Next, the adder 89 analog-adds the incident position pulses Pt2, Px, and Py to generate a multi-valued incident position pulse train Pt3 (data superimposer output in FIG. 11).

Similar to the delay generator 23 described in Example 1, the delay unit 87A outputs the delay signal Dx corresponding to one of the X channel numbers of detector cells 7 ₁ through 7 ₆₄ analog electrical pulse P is output delayer 87B outputs a delay signal Dy which corresponds to one of the Y channel numbers of detector cells 7 ₁ through 7 ₆₄ analog electrical pulse P is output. As described above, the pulse width Pw8 of the incident position pulse Px and the pulse width Pw9 of the incident position pulse Py constituting the incident position pulse train Pt3 are the X channel number and Y channel number of the detection cell 7 from which the analog electric pulse P is output. Each means. The pulse widths Pw6 and Pw7 of the pulses Pp3 and Pp4 of the incident position pulse train Pt3, the time difference Pw4 from the rise of the pulse Pp3 to the fall of the pulse Pp4, and the time difference Pw5 from the fall of the pulse Pp3 to the rise of the pulse Pp4 are analog electric pulses. Since it changes depending on the magnitude of P, it means the peak value H of the analog electric pulse P. The rise and fall of the incident position pulse train Pt3 means the timing at which radiation enters the detection cell 7.

  In the fourth embodiment, Px and Py are generated by using D flip-flops in the data superimposing unit 13, but the data superimposing unit 13 is constituted by other circuits such as the CR and the comparison circuit as shown in the second embodiment. It doesn't matter.

  According to the radiation detector 1 according to the fourth embodiment, the pulse width modulation circuit 11 includes two comparators 81A and 81B, and the analog electric pulse P is predetermined by using the comparators 81A and 81B. Digital electric pulses Pp1 and Pp2 are output by binarizing with threshold voltages Vth1 and Vth2, respectively. Thereby, more accurate peak value and timing information can be obtained. As described above, in the first and second embodiments, the threshold voltage Vth of the pulse modulation circuit 11 is set to one. However, in the fourth embodiment, two or more threshold voltages are set and more accurate. The pulse peak value and timing information are obtained. Of course, three or more threshold voltages may be set to obtain a more accurate pulse peak value and timing information, which may be added to the incident position pulse train.

  According to the radiation detector 1 according to the fourth embodiment, the data superimposing unit 13 is incident using a multi-value logic method in which the pulse width (the width of the pulse time axis) and the pulse amplitude (the width of the pulse voltage axis) are different. The position pulse train Pt3 is output. Thereby, each pulse can be analog-added to output an incident position pulse train Pt3 having a different pulse width and pulse amplitude.

  The present invention is not limited to the above embodiment, and can be modified as follows.

  (1) In each of the above-described embodiments, the radiation detector 1 provided in the PET apparatus has been described as an example. However, the radiation detector 1 provided in a SPECT (Single Photon Emission Computed Tomography) apparatus may be used. .

  (2) In the first and second embodiments described above, the case where the incident position pulses Px and Py are superimposed on the digital electric pulse Pp has been described as an example, but the incident position pulses Px and Py are subsequently output after the output of the digital pulse Pp. May be added.

  (3) In the above-described first and second embodiments, it is assumed that radiation is incident on one of the detection cells 7 connected to the same compressor 17, but other events are simultaneously or short-time different. An event may also occur in the detection cell 7. In that case, the analog electric pulses P of all the detection cells 7 may be added in advance, and if it is determined that the signal level is two or more, a circuit for removing the signal may be added.

  As described above, the present invention is suitable for detecting the position of radiation incident on a detection cell in a short time when detecting radiation with a large number of detection cells.

Claims (16)

  In a radiation detector comprising a plurality of detection cells for detecting radiation by converting light emission due to the incidence of radiation into analog electrical pulses, the analog electrical pulses are binarized with a predetermined threshold value and output as digital electrical pulses A radiation detector, comprising: a pulse width modulation unit for performing an operation; and a position information adding unit for outputting an incident position pulse train obtained by adding information on the position of the detection cell on which radiation is incident to the electric pulse.   2. The radiation detector according to claim 1, wherein the position information adding means outputs the incident position pulse train in synchronization with a timing when the analog electric pulse exceeds and falls below a predetermined threshold value. Detector.   3. The radiation detector according to claim 1 or 2, wherein the width of each pulse constituting the incident position pulse train is an X channel number and a Y channel number of the detection cells arranged in two dimensions composed of an X direction and a Y direction. A radiation detector characterized by being.   4. The radiation detector according to claim 1, wherein the width of each pulse constituting the incident position pulse train is an X channel number and Y of the detection cells arranged in a three-dimensional manner consisting of an X direction, a Y direction, and a Z direction. A radiation detector characterized by a channel number and a Z channel number.   5. The radiation detector according to claim 1, wherein a pitch of each pulse constituting the incident position pulse train is proportional to a peak value of the analog electric pulse.   6. The radiation detector according to claim 1, further comprising: a pulse train compressing unit that compresses the incident position pulse train and outputs a compressed pulse train; and a pulse train restoring unit that restores the compressed pulse train to the incident position pulse train. A radiation detector.   7. The radiation detector according to claim 6, wherein the pulse train compression means is provided for each group composed of a plurality of the detection cells, and the compressed pulse train is output for each group and output for each group. A radiation detector comprising: group position information adding means for outputting, for each group, a group pulse train obtained by adding information related to the position of the group to a compressed pulse train.   8. The radiation detector according to claim 7, wherein group compression means for compressing the group pulse train and outputting a group compressed pulse train, and restoring the group compressed pulse train to the group pulse train to restore the group pulse train to the compressed pulse train. A radiation detector comprising a group restoring means.   7. The radiation detector according to claim 1, wherein the position information adding means includes a delay circuit (B) that outputs a delay signal (A) that is output corresponding to information on the position of the detection cell, and the electric circuit. A radiation detector comprising: a logic circuit (C) that outputs the incident position pulse train when a pulse and the delay signal (A) are inputted.   10. The radiation detector according to claim 9, wherein in the logic circuit (C), one pulse constituting the incident position pulse train falls in synchronization with a rise of the delay signal (A) to constitute the incident position pulse train. Another pulse that falls in synchronization with the fall of the delay signal (A) and outputs the incident position pulse train by superimposing the one pulse and the other pulse in a row. Characteristic radiation detector.   7. The radiation detector according to claim 1, wherein the position information adding means includes a capacitor having a capacity corresponding to information on the position of the detection cell and a resistor having a resistance value, and outputs a delay signal (D). A delay circuit (E) for outputting, a comparator for outputting each pulse constituting the incident position pulse train when the delay signal (D) exceeds a predetermined threshold compared to a predetermined threshold; A radiation detector comprising: a logic circuit (F) that outputs the incident position pulse train by superimposing the pulses output from the comparator in a row.   9. The radiation detector according to claim 7, wherein the group position information adding means includes a delay circuit (H) that outputs a delay signal (G) that is output corresponding to information on the position of the group, and the compression. A radiation detector comprising: a logic circuit (I) that outputs the group pulse train when a pulse train and the delay signal (G) are inputted.   13. The radiation detector according to claim 12, wherein the logic circuit (I) includes another pulse that constitutes the group pulse train when one pulse constituting the group pulse train falls in synchronization with a rise of the delay signal (G). Is a logic circuit that falls in synchronization with the fall of the delay signal (G) and outputs the group pulse train by superimposing the one pulse and the other pulse in a row. Radiation detector.   9. The radiation detector according to claim 7, wherein the group position information adding means includes a capacitor having a capacity corresponding to information on the position of the group and a resistor having a resistance value, and outputs a delay signal (J). A delay circuit (K) for outputting, and a comparator (L) for outputting each pulse constituting the group pulse train when the delay signal (J) exceeds a predetermined threshold value compared with a predetermined threshold value; And a logic circuit (M) that outputs the group pulse train by superimposing pulses output from the comparator in a row.   7. The radiation detector according to claim 1, wherein the pulse width modulation means is composed of a plurality of comparators, and each of the comparators is used to binarize the analog electric pulse with a predetermined threshold value. A radiation detector characterized in that it outputs a digital electric pulse.   7. The radiation detector according to claim 1, wherein the position information adding means outputs the incident position pulse train by using a multi-value logic method having different pulse widths and pulse amplitudes.

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