JPS61275684A - Semiconductor radiation position detecting device - Google Patents

Abstract

PURPOSE:To improve counting rate characteristics by providing plural channels of energy signal processing systems which select outputs of radiation detecting elements arrayed in a matrix in parallel. CONSTITUTION:Outputs of a delay circuit and a buffer amplifier 6 are inputted to analog multiplexers 71 and 72 and selected signals are sent to peak holding circuits 91 and 92 through main amplifiers 81 and 82. Respective pulse outputs of a discriminator 4 are inputted to a latch and encoder 120 and a position signal X is sent to latch circuits 141 and 142, selected by a selector 210, and then outputted through a circuit 214. Outputs of the circuits 91 and 92 are selected by a selector 20 and then inputted to a height analyzer 100 as an energy signal Z through a sample and hold circuit 209. When the waveform of the signal Z is within a specific energy range, it is sent to a timing control circuit 110, which outputs a signal UNBLAK, so that counting characteristics are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to improvement of a semiconductor radiation position detection device. Equipment (computed tomography equipment)
It is useful for obtaining a distribution image of a specific R1 (radioisotope) nuclide by detecting the two-dimensional position of radiation of a specific energy, such as, and is also used in other fields such as science and engineering.

2. Description of the Related Art A semiconductor radiation position detection device that detects the two-dimensional position of radiation by arranging a large number of semiconductor radiation detection elements in a matrix has conventionally been constructed, for example, as shown in FIG. -247109, patent application 1986-135
493). In this figure, the semiconductor radiation detection element array l is made of, for example, Ge, Si, CdTe, Hg I
In Figure 0, which shows a large number of semiconductor radiation detection elements using compound semiconductors such as x arranged in a matrix, the elements are arranged in a 4×4 pattern for simplicity. The signals from each of these elements may be input to a preamplifier, but in this case, the signal from each element is input to a preamplifier 2.3 provided for each row and each column, which is common to each row and each column. I am trying to input it into . The signals for each row arranged in the X direction are sent to the corresponding discriminator 4 via the corresponding preamplifier 2, and if the signal is greater than the threshold level, a pulse is sent to the latch and encoder 12 to disable the latch. Then, the encoder 12 performs conversion into a code signal, and a position signal X (digital signal) corresponding to the row in which a signal greater than the threshold level is generated is outputted via the latch circuit 14. On the other hand, the signals for each column arranged in the Y direction are sent to the corresponding discriminator 5 via the corresponding preamplifier 3, and if the signal is greater than the threshold level, a pulse is sent to the latch and encoder 13. The latch and encoder 13 convert the signal into a code signal, and the position signal Y(
digital signal) is outputted via the latch circuit 15.

Each output of the preamplifier 2 is sent to an analog multiplexer 7 through a delay circuit and a buffer amplifier 6, and one of the signals is selected.The selected signal is waveform-shaped by the main amplifier 8. Further, it is inputted as an energy signal Z to a pulse height analyzer IO via a peak hold circuit 9.

In this way, it is determined whether or not the wave height of the energy signal Z is within a predetermined energy range. If it is within the range, a signal is sent to the timing control circuit 11, and in response, the timing control circuit 11 outputs the UNBLANK signal. . The timing control circuit 11 is triggered by the output of the discriminator 2.3, and has a coincidence function that detects when the output of the discriminator 2 and the output of the discriminator 3 are input at the same time. control the timing of each circuit appropriately. The output data of the latch and encoder 12 are input to an analog multiplexer control circuit 16, which controls the analog multiplexer 7 to select a delay circuit and a buffer amplifier 6 corresponding to the discriminator 4 that has generated the pulse. It is controlled so that only the output signal of

Problems to be Solved by the Invention Incidentally, in the conventional configuration shown in FIG. In this case, only the signal of element a will be processed by main amplifier 8 and peak hold circuit 9. Therefore, only the signal of element a is counted, and the signals of element C and element d are omitted, resulting in a problem that the counting rate characteristic is low.

Therefore, conventionally, it has been considered to divide the matrix-shaped semiconductor radiation detection element array 1 into a plurality of regions and provide each region with an independent signal processing circuit as shown in FIG.

By dividing the area in this way and providing an independent signal processing circuit for each area, it is true that under uniform radiation irradiation conditions, the overall count rate characteristics are apparently improved by the magnification corresponding to the number of divisions. Ru.

However, in applications such as nuclear medicine diagnosis, especially cardiac examination, high concentration of RI is often localized, and under such conditions, only the signal processing circuit for a specific region operates mainly. , and the count rate characteristics are not improved.

An object of the present invention is to provide a semiconductor radiation position detection device that can improve count rate characteristics under conditions where high concentration RI is localized in the same way as under uniform irradiation conditions with a simple circuit configuration. With the goal.

Means for Solving the Problems In the semiconductor radiation position detection device according to the present invention, for each radiation incident event, one of the signals related to the output of the preamplifier into which the output of each detection element is input is transferred to an analog multiplexer. A plurality of channels are provided in parallel with an energy signal processing system in which the selected signal is waveform-shaped and amplified by an energy signal processing circuit.

Since a plurality of channels of the action energy signal processing system are provided in parallel, when any one channel is in operation, the other channels are operated to enable parallel processing. By the way, the count rate characteristic is mainly defined by the energy signal processing system. Therefore, by providing a plurality of channels of energy signal processing systems in parallel and operating them in parallel, the count rate characteristics can be improved.

Embodiment In FIG. 1, each output of the delay circuit and buffer amplifier 6 is input to two analog multiplexers 71.72, and the signals selected by these are input to the main amplifier 81.8.
The energy signal processing channel is configured to have two channels, such that the energy signal is sent to the peak hold circuits 91 and 92 through the energy signal processing channel 2 and the peak hold circuit 91 and 92, respectively. The configuration before the delay circuit and buffer amplifier 6 is the same as that in FIG. 2, so it is omitted.

Each pulse output of the discriminator 4 is input to the latch and encoder 120, where it is converted into a code signal, and the position signal ) Latch circuit 2 after being selected at 210
14 and is outputted.

The above two analog multiplexers 71 and 72 respectively correspond to those of the discriminator 4 that generate pulses by the analog multiplexer control circuits 161 and 162 to which the output data of the latch and encoder 120 are input. It is controlled to pass only the output signals of the delay circuit and buffer amplifier 6. After each output of the peak hold circuits 91 and 92 is selected by a selector (analog multiplexer) 200, it passes through a sample/hold circuit 209 and is sent to the pulse height analyzer 10 as an energy signal Z.
It is input to 0. In this way, it is determined whether or not the wave height of the energy signal Z is within a predetermined energy range. If it is within the range, a signal is sent to the timing control circuit 110, and in response, the timing control circuit 110 outputs the UNBLANK signal. . The timing control circuit 110 is almost the same as the timing control circuit 11 in FIG. 2, has a coincidence function, and in addition to appropriately controlling the timing of each circuit, performs the following control.

First, analog multiplexers 71, 72, main amplifier 8
1.82, When both of the two energy signal processing channels consisting of the peak hold circuit 91.92 are inactive, when a radiation detection signal is input, priority is given to the channel that became inactive first. perform signal processing. If one of the channels is in operation and another radiation detection signal is input, control is performed so that the signal processing is performed in the free channel.0 If both channels are in operation, the reception of the next signal is controlled. Refuse to attach. Further, the latch circuits 141 and 142 are operated depending on which of the two channels is operating, and the selector 210 is controlled to select the output of either of the latch circuits 141 or 142.

Note that this position signal output system only needs to output the position signal in synchronization with the energy signal processing channel, so in addition to the configuration in which two latch circuits are provided and selected, the FI
FO circuit (high-speed input/high-speed output circuit using memory)
Other configurations such as

Further, although the circuit related to the position signal Y is omitted in the above, it may be configured in the same manner as the circuit related to the position signal X.

Since the above is one embodiment of the present invention, various changes can be made without departing from the spirit of the invention. For example, three or more energy signal processing channels can be provided in parallel. It goes without saying that the present invention can be applied to detection element arrays other than 4x4, and can also be applied to semiconductor radiation position detection devices with other configurations, such as a configuration in which a preamplifier is provided for each detection element.

Further, the present invention can be applied to a multilayer slice emission CT device and the like in addition to a two-dimensional radiation detection device such as a normal gamma camera.

Effects of the Invention According to the present invention, count rate characteristics can be significantly improved with a simple circuit configuration without deterioration of various properties such as position resolution and energy resolution. High count rate characteristics can be obtained not only under conditions where the RI distribution is uniform, but also under conditions where the RI is localized.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional example. 1... Semiconductor radiation detection element array 2.3... Preamplifier 4.5... Discriminator 6... Delay circuit and buffer amplifier 7.71.72
... Analog multiplexer 8.81.82 ... Main amplifier 9.91.92 ... Peak hold circuit 10.100
... Wave height analyzer 11.110 ... Timing control circuit 12.13,1
20...Latch and encoder 14.15.141
, 142, 214...Latch circuit 18.181, 18
2...Analog multiplexer control circuit 200.21
0...Selector

Claims (1)

[Claims] (1) In a semiconductor radiation position detection device that detects the two-dimensional position of radiation by arranging a large number of semiconductor radiation detection elements in a matrix, a preamplifier receives the output of each of the detection elements for each radiation incident event. an analog multiplexer that selects any one of the signals related to the output;
A semiconductor radiation position detection device characterized in that a plurality of parallel channels of an energy signal processing system including an energy signal processing circuit that performs waveform shaping processing and amplification of the selected signal are provided.