CN112149787A - Counting device and counting system based on capacitance feedback charge sensitive amplifying circuit - Google Patents
Counting device and counting system based on capacitance feedback charge sensitive amplifying circuit Download PDFInfo
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Abstract
The application provides a counting device and a counting system based on a capacitance feedback charge sensitive amplifying circuit. The counting device based on the capacitance feedback charge sensitive amplifying circuit comprises: the device comprises a detector, an amplifying circuit, a threshold judging circuit and a counting circuit. The detector is used for receiving the X-ray and outputting the charge quantity related to the energy of the X-ray. The amplifying circuit is used for outputting a corresponding voltage value according to the charge quantity. The input end of the amplifying circuit is connected with the output end of the detector. The amplifying circuit includes an amplifier and a feedback capacitor. The feedback capacitor is connected in parallel with the amplifier. The input end of the threshold judging circuit is electrically connected with the output end of the amplifying circuit. The threshold judging circuit is used for receiving the voltage value and determining whether to output the trigger signal according to the voltage value. The counting circuit is used for quantizing and counting the voltage value according to the trigger signal. The first input end of the counting circuit is connected with the output end of the threshold judging circuit. And the second input end of the counting circuit is connected with the output end of the amplifying circuit.
Description
Technical Field
The application relates to the technical field of computer tomography imaging equipment, in particular to a counting device and a counting system based on a capacitance feedback charge sensitive amplifying circuit.
Background
In a Computed Tomography (CT) apparatus, the energy distribution of X-rays generated by a bulb is continuous. Conventional detectors based on scintillator charge integration acquire average information of the energy of the mixed rays passing through the scanned object. Therefore, conventional images reconstructed from data acquired by conventional detectors exhibit the averaging effect of mixed energies.
While mixed energy X-ray imaging has artifacts due to non-uniform absorption of X-rays by substances or non-uniform density of substances, such as beam hardening, metal artifacts, and the like. The appearance of energy CT well solves the problems encountered in conventional CT, and by identifying the energy level of X-rays passing through the scanned object, the equivalent atomic coefficient of the scanned object is calculated, thereby realizing material identification.
At present, a resistance-capacitance feedback charge sensitive amplifying circuit in an energy CT usually adopts a feedback resistor with a large resistance value, so that the discharge time of a capacitor in the amplifying circuit is increased, the counting rate is reduced, and the circuit noise is increased.
Disclosure of Invention
Therefore, it is necessary to provide a counting device and a counting system based on a capacitance feedback charge sensitive amplifying circuit, aiming at the problems that the existing resistance-capacitance feedback charge sensitive amplifying circuit in the CT usually adopts a feedback resistor with a large resistance value, which not only increases the discharge time of a capacitor in the amplifying circuit, resulting in a decrease in the counting rate, but also increases the circuit noise.
A counting device based on a capacitance feedback charge sensitive amplifying circuit comprises:
a detector for receiving X-rays and outputting a charge amount related to an energy of the X-rays;
the amplifying circuit is used for outputting a corresponding voltage value according to the electric charge quantity, the input end of the amplifying circuit is connected with the output end of the detector, the amplifying circuit comprises an amplifier and a feedback capacitor, and the feedback capacitor is connected with the amplifier in parallel;
the input end of the threshold judging circuit is electrically connected with the output end of the amplifying circuit, and whether a trigger signal is output or not is determined according to the voltage value; and
and the counting circuit is used for quantizing and counting the voltage value according to the trigger signal, a first input end of the counting circuit is connected with an output end of the threshold judging circuit, and a second input end of the counting circuit is connected with an output end of the amplifying circuit.
In one embodiment, the amplifying circuit further includes:
the first end of the amplifier, the first end of the feedback capacitor and the first end of the reset switch are connected to the output end of the detector in a shared mode, the second end of the amplifier is grounded, and the output end of the amplifier is connected to the second end of the feedback capacitor, the second end of the reset switch and the input end of the threshold judging circuit in a shared mode.
In one embodiment, when the counting circuit receives the trigger signal within a preset period, the counting circuit quantizes and counts the voltage value based on a preset delay time, and after one quantization and counting is completed, the amplifying circuit resets and receives the charge amount again.
In one embodiment, the amplifying circuit further includes:
and a first end of the capacitance switch is electrically connected with a second end of the feedback capacitor, and a second end of the capacitance switch is electrically connected with a first end of the amplifier.
In one embodiment, the number of the capacitance switches is the same as that of the feedback capacitors, and the capacitance switches are electrically connected with the feedback capacitors in a one-to-one correspondence manner.
In one embodiment, the voltage value output by the amplifying circuit is proportional to the amount of charge.
In one embodiment, the threshold discrimination circuit includes:
a first end of the first comparator is electrically connected with the output end of the amplifying circuit, a second end of the first comparator is used for acquiring a preset voltage threshold, and the output end of the first comparator is electrically connected with the counting circuit;
the first comparator is used for comparing the voltage value with the preset voltage threshold value, and if the voltage value is greater than or equal to the preset voltage threshold value, the first comparator outputs the trigger signal to the counting circuit.
In one embodiment, the counting circuit comprises:
the timing driver is electrically connected with the threshold judging circuit, and when receiving the trigger signal, the timing driver starts timing and outputs a driving signal when reaching the preset delay time;
the comparison circuit is respectively electrically connected with the output ends of the timing driver and the amplification circuit and is used for receiving the voltage value based on the driving signal and outputting a comparison result;
the exclusive-OR logic circuit is electrically connected with the comparison circuit and is used for acquiring the comparison result and outputting an exclusive-OR logic result based on the comparison result;
an adder electrically connected to the timing driver and the exclusive or logic circuit, respectively; and
and the counting register is respectively and electrically connected with the timing driver and the adder, the adder carries out accumulation counting on the quantized value in the counting register based on the exclusive-or logic result and outputs the current quantized value to the counting register for storage, and when the counting register finishes one-time quantization and counting, the amplifying circuit resets and receives the electric charge again.
In one embodiment, the comparison circuit comprises at least: the first end of the second comparator and the first end of the third comparator are both electrically connected with the output end of the amplifying circuit, the second end of the second comparator is used for inputting a first threshold voltage, and the second end of the third comparator is used for inputting a second threshold voltage;
the exclusive-or logic circuit at least comprises an exclusive-or gate, wherein a first end of the exclusive-or gate is electrically connected with the output end of the second comparator, a second end of the exclusive-or gate is electrically connected with the output end of the third comparator, and an output end of the exclusive-or gate is electrically connected with the adder;
the second comparator outputs a first comparison result based on the first threshold voltage and the voltage value, the third comparator outputs a second comparison result based on the second threshold voltage and the voltage value, and the exclusive or gate outputs an exclusive or logic result to the adder according to the first comparison result and the second comparison result.
In one embodiment, the first threshold voltage and the second threshold voltage are different.
In one embodiment, the counting device based on the capacitive feedback charge-sensitive amplification circuit further includes:
and the switch is connected between the detector and the input end of the amplifying circuit in series.
A counting system comprising a plurality of counting devices based on the capacitive feedback charge sensitive amplification circuit according to any one of the above embodiments; and
and the controller is respectively electrically connected with each amplifying circuit and each counting circuit, and controls the amplifying circuit corresponding to the counting circuit to reset and receive the charge amount again when the counting circuit finishes one-time quantization and counting.
Compared with the prior art, the counting device and the counting system based on the capacitance feedback charge sensitive amplifying circuit receive X rays through the detector and output the charge quantity to the amplifying circuit, and the voltage value output to the threshold judging circuit by the amplifying circuit is gradually increased by utilizing the parallel cooperation of the feedback capacitor in the amplifying circuit and the amplifier. When the voltage value is larger than or equal to a preset voltage threshold value, the threshold judging circuit outputs a trigger signal to a counting circuit, so that the counting circuit quantizes and counts the voltage value according to the trigger signal. This application adopts above-mentioned structure, not only improves the discharge time of electric capacity among the amplifier circuit, promotes the count rate, has still reduced circuit noise, increases the stability of circuit.
Drawings
Fig. 1 is a schematic circuit diagram of a counting device based on a capacitive feedback charge sensitive amplifier according to an embodiment of the present application;
fig. 2 is a first circuit schematic diagram of a counting device based on a capacitive feedback charge-sensitive amplifier circuit according to an embodiment of the present disclosure;
fig. 3 is a second schematic circuit diagram of a counting device based on a capacitive feedback charge-sensitive amplifying circuit according to an embodiment of the present disclosure;
fig. 4 is a third schematic circuit diagram of a counting device based on a capacitive feedback charge-sensitive amplifying circuit according to an embodiment of the present disclosure;
fig. 5 is a fourth schematic circuit diagram of a counting device based on a capacitive feedback charge-sensitive amplifying circuit according to an embodiment of the present disclosure;
FIG. 6 is a waveform diagram of a counting pulse according to an embodiment of the present application;
fig. 7 is a schematic diagram of a counting system according to an embodiment of the present application.
10. A counting device based on a capacitance feedback charge sensitive amplifying circuit; 11. a controller; 100. a detector; 20. a counting system; 200. an amplifying circuit; 210. an operational amplifier; 220. a feedback capacitance; 230. a reset switch; 240. a capacitive switch; 300. a threshold discrimination circuit; 310. a first comparator; 400. a counting circuit; 410. a timing driver; 420. a comparison circuit; 421. a second comparator; 422. a third comparator; 423. a fourth comparator; 424. a fifth comparator; 430. an exclusive or logic circuit; 431. an exclusive-or gate; 432. a first exclusive-or gate; 433. a second exclusive or gate; 440. an adder; 450. a count register; 500. and (4) switching.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the present application are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is capable of embodiments in many different forms than those described herein and those skilled in the art will be able to make similar modifications without departing from the spirit of the application and it is therefore not intended to be limited to the embodiments disclosed below.
It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1, an embodiment of the present application provides a counting device 10 based on a capacitive feedback charge sensitive amplifier circuit, including: detector 100, amplifier circuit 200, threshold discrimination circuit 300, and counting circuit 400. The detector 100 is configured to receive X-rays and output a charge amount related to an energy of the X-rays. The amplifying circuit 200 is configured to output a corresponding voltage value according to the amount of charge. The input of the amplifying circuit 200 is connected to the output of the detector 100. The amplifying circuit 200 includes an amplifier 210 and a feedback capacitor 220. The feedback capacitor 220 is connected in parallel with the amplifier 210.
The input end of the threshold judging circuit 300 is electrically connected with the output end of the amplifying circuit 200. The threshold judging circuit 300 is configured to receive the voltage value and determine whether to output a trigger signal according to the voltage value. The counting circuit 400 is configured to quantize and count the voltage value according to the trigger signal. A first input terminal of the counting circuit 400 is connected to an output terminal of the threshold judging circuit 300. A second input terminal of the counting circuit 400 is connected to an output terminal of the amplifying circuit 200.
In one embodiment, the detector 100 may be a semiconductor detector. Specifically, the semiconductor detector may be made of CdZnTe (cadmium zinc telluride), CdTe (cadmium telluride), or other materials, as well as electrodes and a bias circuit. When the detector 100 is irradiated with X-rays, the detector 100 generates a corresponding amount of charge and outputs the amount of charge to the amplifier 210 in the amplifying circuit 200.
In one embodiment, as shown in fig. 2, the amplification circuit 200 further includes a reset switch 230. The first terminal of the operational amplifier 210, the first terminal of the feedback capacitor 220, and the first terminal of the reset switch 230 are commonly connected to the output terminal of the detector 100. A second terminal of the operational amplifier 210 is grounded. The output terminal of the operational amplifier 210 is commonly connected to the second terminal of the feedback capacitor 220 and the second terminal of the reset switch 230.
In one embodiment, the reset switch 230 is in an off state when the amplifying circuit 200 (i.e., the amplifier 210) receives the amount of charge. Assuming that the amount of charge output by the detector 100 to the amplifier 210 is Q, the capacitance value of the feedback capacitor 220 is CfThen, the voltage value Vo output by the amplifier 210 is:
the voltage Vo output by the amplifier 210 continuously increases due to the accumulation of the charge amount on the feedback capacitor 220. In this process, the reset switch 230 is always in an off state. The amount of charge generated by the detector 100 is proportional to the energy level of the incident X-rays. Therefore, as can be seen from the above formula, the voltage value output by the amplifier 210 is proportional to the charge amount. Therefore, the counting circuit 400 detects the voltage value, i.e. the energy level of the incident X-ray can be obtained.
The threshold discrimination circuit 300 receives the voltage value output by the amplifier 210 and compares the voltage value with a preset voltage threshold. If the voltage value is smaller than the preset voltage threshold, the threshold determination circuit 300 outputs a low level to the counting circuit 400, and at this time, the counting circuit 400 does not operate. If the voltage value is greater than or equal to the preset voltage threshold, the threshold determination circuit 300 outputs a high level (i.e., a trigger signal) to the counting circuit 400. At this time, the counting circuit 400 may quantize and count the voltage value according to the trigger signal. In one embodiment, the trigger signal is high.
Specifically, the counting circuit 400 starts timing after receiving the trigger signal, and when the timing time reaches the preset delay time, the counting circuit 400 quantizes and counts the voltage value. In an embodiment, the preset delay time may be set according to an actual requirement, and the specific time is not limited herein. The preset delay time may be input to the counting circuit 400 through a timer. The preset delay time may also be set in advance in the counting circuit 400.
Meanwhile, when the counting circuit 400 completes one quantization and counting, the reset switch 230 is reset (i.e., the reset switch 230 is closed) once. The reset operation of the reset switch 230 can drain the charge accumulated in the feedback capacitor 220, thereby completing the reset of the feedback capacitor 220. When the charge accumulated in the feedback capacitor 220 is completely discharged, the reset switch 230 is turned off again, and the amplifier 210 receives the charge again. In one embodiment, the closing and opening of the reset switch 230 may be controlled by a controller.
In one embodiment, the predetermined period refers to a time when the detector 100 receives one X-ray scan. The specific value of the preset period can be set according to actual requirements, and the specific time is not particularly limited here. In one embodiment, the counting circuit 400 may complete a plurality of counting processes within the preset period, and after all counting is completed, the counting circuit 400 outputs a final counting result.
It is to be understood that the specific circuit structure of the threshold judging circuit 300 is not limited as long as it has a function of determining whether to output a trigger signal based on the voltage value and a preset voltage threshold. In one embodiment, the threshold discrimination circuit 300 may be a comparator. Since the noise signals of the detector 100 and the amplifying circuit 200 have high-speed and low-amplitude characteristics, the influence of the noise signals on the counting result can be effectively removed by setting the threshold judging circuit 300 appropriately.
It is to be understood that the specific circuit structure of the counting circuit 400 is not limited as long as the function of quantizing and counting the voltage value based on the trigger signal is provided. In one embodiment, the counting circuit 400 may be constructed by a timer, a comparator, an exclusive or gate, an adder, and a register. When the counting circuit 400 receives the trigger signal in a preset period, the counting circuit 400 may quantize and count the voltage value once based on the preset delay time, and when one quantization and counting is completed, the reset switch 230 is reset to drain the charge stored in the feedback capacitor 220, so that the amplifier 210 receives the charge amount again. In this way, the discharge time of the feedback capacitor 220 can be increased, thereby increasing the counting rate of the counting circuit 400.
In this embodiment, the detector 100 receives the X-ray and outputs the charge amount to the amplifying circuit 200, and the feedback capacitor 220 in the amplifying circuit 200 is in parallel connection with the amplifier 210, so that the voltage value output by the amplifying circuit 200 to the threshold judging circuit 300 is gradually increased. When the voltage value is greater than or equal to the preset voltage threshold, the threshold determination circuit 300 outputs a trigger signal to the counting circuit 400, so that the counting circuit 400 quantizes and counts the voltage value according to the trigger signal. This embodiment adopts above-mentioned structure, not only improves the discharge time of electric capacity among the amplifier circuit 200, promotes the count rate, has still reduced circuit noise, increases the stability of circuit.
Referring to fig. 3, in an embodiment, the amplifying circuit 200 further includes: a capacitive switch 240. A first terminal of the capacitive switch 240 is electrically connected to a second terminal of the feedback capacitor 220. A second terminal of the capacitive switch 240 is electrically connected to a first terminal of the amplifier 210. In one embodiment, the capacitive switch 240 can be controlled to be closed and opened by a controller. In one embodiment, the capacitive switch 240 may be a semiconductor switch. The capacitance switch 240 may also be a relay switch.
In one embodiment, the number of the feedback capacitors 220 is plural, and the feedback capacitors 220 are connected in parallel with each other. The number of the capacitive switches 240 is the same as that of the feedback capacitors 220, and the capacitive switches 240 are electrically connected to the feedback capacitors 220 in a one-to-one correspondence manner. That is, each of the feedback capacitors 220 corresponds to one of the capacitive switches 240. The plurality of capacitance switches 240 are opened or closed independently or in combination with each other, so that the plurality of feedback capacitors 220 can be combined, thereby obtaining different feedback capacitance values (i.e. different charge feedback coefficients), and further realizing multi-stage measurement of the voltage value.
In one embodiment, the threshold discrimination circuit 300 includes: a first comparator 310. A first terminal of the first comparator 310 is electrically connected to an output terminal of the amplifying circuit 200. The second terminal of the first comparator 310 is used for obtaining the preset voltage threshold. The output terminal of the first comparator 310 is electrically connected to the counting circuit 400. The first comparator 310 is configured to compare the voltage value with the preset voltage threshold. If the voltage value is greater than or equal to the preset voltage threshold, the first comparator 310 outputs the trigger signal to the counting circuit 400. If the voltage value is smaller than the preset voltage threshold, the first comparator 310 outputs a low level to the counting circuit 400.
In one embodiment, the first comparator 310 may perform a difference comparison between the voltage value and the preset voltage threshold, and obtain a difference comparison result. If the difference comparison result indicates that the voltage value is smaller than the preset voltage threshold, the first comparator 310 outputs a low level to the counting circuit 400, and the counting circuit 400 does not operate at this time. If the difference comparison result indicates that the voltage value is greater than or equal to the preset voltage threshold, the first comparator 310 outputs the trigger signal to the counting circuit 400, and the counting circuit 400 operates at this time. The threshold decision circuit 300 formed by the first comparator 310 can effectively remove the influence of noise signals on the counting result.
Referring to fig. 4, in one embodiment, the counting circuit 400 includes: timing driver 410, comparison circuit 420, exclusive-or logic circuit 430, adder 440, and count register 450. The timing driver 410 is electrically connected to the threshold decision circuit 300. When the timing driver 410 receives the trigger signal, the timing driver 410 starts timing and outputs a driving signal when the preset delay time is reached. The comparison circuit 420 is electrically connected to the timing driver 410 and the output terminal of the amplifier 210, respectively. The comparison circuit 420 is configured to receive the voltage value based on the driving signal and output a comparison result.
The exclusive or logic circuit 430 is electrically connected to the comparison circuit 420. The exclusive-or logic circuit 430 is configured to obtain the comparison result and output an exclusive-or logic result based on the comparison result. The adder 440 is electrically connected to the timing driver 410 and the exclusive or logic circuit 430, respectively. The count register 450 is electrically connected to the timing driver 410 and the adder 440, respectively. The adder 440 counts up the quantization value in the count register 450 based on the xor logic result, and outputs the current quantization value to the count register 450 for storage, and when the count register 450 completes one quantization and counting, the amplifying circuit 200 resets and receives the charge again.
In one embodiment, when the timing driver 410 receives the trigger signal, the timing driver 410 starts timing and determines whether the timing time reaches the preset delay time. If it is determined that the timing time reaches the preset delay time, the timing driver 410 outputs the driving signal to the comparing circuit 420, the adder 440, and the counting register 450. That is, when the timing time reaches the preset delay time, the timing driver 410 outputs the driving signal to drive the comparison circuit 420, the adder 440 and the count register 450 to start operating. In one embodiment, the preset delay time may be set in advance in the timing driver 410. The preset delay time may also be input to the timing driver 410 by a clock signal.
In one embodiment, the comparison circuit 420 includes at least: a second comparator 421 and a third comparator 422. Specifically, a first end of the second comparator 421 and a first end of the third comparator 422 are both electrically connected to the output end of the amplifier 210. The second terminal of the second comparator 421 is used for inputting a first threshold voltage. The second terminal of the third comparator 422 is used for inputting a second threshold voltage. The second comparator 421 outputs a first comparison result based on the first threshold voltage and the voltage value. The third comparator 422 outputs a second comparison result based on the second threshold voltage and the voltage value.
In one embodiment, the first threshold voltage and the second threshold voltage may be set according to actual requirements, and it is only necessary to ensure that the first threshold voltage and the second threshold voltage are different. In one embodiment, the second comparator 421 may compare the voltage value with the first threshold voltage. And if the voltage value is smaller than the first threshold voltage, outputting the first comparison result as a low level. And if the voltage value is greater than or equal to the first threshold voltage, outputting the first comparison result as a high level.
In one embodiment, the third comparator 422 may compare the voltage value with the second threshold voltage. And if the voltage value is smaller than the second threshold voltage, outputting the second comparison result as a low level. And if the voltage value is greater than or equal to the second threshold voltage, outputting the first comparison result as a high level.
In one embodiment, the exclusive-or logic 430 includes at least one exclusive-or gate 431. A first terminal of the xor gate 431 is electrically connected to an output terminal of the second comparator 421. A second terminal of the xor gate 431 is electrically connected to an output terminal of the third comparator 422. The output of the exclusive or gate 431 is electrically connected to the adder 440. The xor gate 431 outputs an xor logical result to the adder 440 according to the first comparison result and the second comparison result.
When the first comparison result and the second comparison result received by the xor gate 431 are the same (i.e., the first comparison result and the second comparison result are both high or low), the xor logic result (trig0) output by the xor gate 431 is 0. That is, the xor logic result received by the adder 440 at this time is 0, which indicates that the first threshold voltage and the second threshold voltage are not set properly at this time. I.e. the voltage value does not fall within the threshold interval of the first and second threshold voltages. That is, at this time, the adder 440 may determine that the xor logic result is not normal, and the adder 440 may report an error through the controller.
When the first comparison result and the second comparison result received by the xor gate 431 are not the same (i.e., the first comparison result and the second comparison result are not high or low), the xor logic result output by the xor gate 431 is 1. That is, the result of the exclusive or logic received by the adder 440 is 1, which indicates that the first threshold voltage and the second threshold voltage are reasonably set. I.e. the voltage value falls within the voltage interval of the first threshold voltage and the second threshold voltage.
That is, at this time, the adder 440 may determine that the xor result is normal, and the adder 440 adds the xor result to the quantization value in the count register 450 and outputs the current quantization value to the count register 450 for storage. Meanwhile, when the counting register 450 completes one quantization and counting, the reset switch 230 in the amplifying circuit 200 is reset, and the amplifier 210 receives the charge amount again.
Referring to fig. 5, the comparison circuit 420 may further include a fourth comparator 423 and a fifth comparator 424. Specifically, a first terminal of the fourth comparator 423 and a first terminal of the fifth comparator 424 are both electrically connected to the output terminal of the amplifier 210. A second terminal of the fourth comparator 423 is used for inputting a third threshold voltage. The second terminal of the fifth comparator 424 is used for inputting a fourth threshold voltage. The fourth comparator 423 outputs a third comparison result based on the third threshold voltage and the voltage value. The fifth comparator 424 outputs a fourth comparison result based on the fourth threshold voltage and the voltage value.
In one embodiment, the third threshold voltage and the fourth threshold voltage may be set according to actual requirements, and it is only necessary to ensure that the first threshold voltage (Vth1), the second threshold voltage (Vth2), the third threshold voltage (Vth3), and the fourth threshold voltage (Vth4) are sequentially set in order of magnitude. Assuming that Vth1, Vth2, Vth3, and Vth4 increase in sequence, the energy detection levels corresponding to the three energy detection levels are: vth4-Vth3, Vth3-Vth2 and Vth2-Vth 1.
In one embodiment, the exclusive or logic circuit 430 may further include a first exclusive or gate 432 and a second exclusive or gate 433. Specifically, a first terminal of the first exclusive or gate 432 is electrically connected to an output terminal of the third comparator 422. A second terminal of the first xor gate 432 is electrically connected to an output terminal of the fourth comparator 423. A first terminal of the second xor gate 433 is electrically connected to an output terminal of the fourth comparator 423. A second terminal of the second xor gate 433 is electrically connected to an output terminal of the fifth comparator 424. The output terminal of the first xor gate 432 and the output terminal of the second xor gate 433 are each electrically connected to one of the adders 440.
The first exclusive or gate 432 outputs a first exclusive or logic result (trig1) based on the second comparison result and the third comparison result. The second exclusive or gate 433 outputs a second exclusive or logic result (trig2) based on the third comparison result and the fourth comparison result. The output of the xor result, the first xor result and the second xor result is as follows:
| amplitude of |
431 | 432 | 433 | trig2：trig1：trig0 |
| Vo＜Vth1 | 0 | 0 | 0 | 000 (threshold setting error) |
| Vth1≤Vo＜ |
1 | 0 | 0 | 001 |
| Vth2≤Vo＜Vth3 | 0 | 1 | 0 | 010 |
| Vth3≤Vo＜Vth4 | 0 | 0 | 1 | 100 |
| Vth4≤Vo | 0 | 0 | 0 | 000 (threshold setting error) |
Wherein the pulse amplitude is the current energy level of the voltage value. As can be seen from the above table, the adder 440 adds the trig (i.e., trig0, trig1, and trig2) value output by the XOR logic 430 to the quantized value in the count register 450 and reassigns the result to the count register 450, i.e., completes a count. Specifically, if the corresponding trig bit output by the xor logic circuit 430 is 1, 1 is added to the corresponding count register 450; if the corresponding trig bit output by the exclusive or logic circuit 430 is 0, the corresponding count register 450 remains unchanged, thereby counting pulses of a specific amplitude.
For example, if the trig value output by the exclusive-or circuit 430 is 010, it indicates that the voltage value falls between Vth3-Vth 2. At this time, the first xor logic result output by the first xor gate 432 is 1, and both the xor logic result and the second xor logic result are 0. That is, the adder 440 corresponding to the first xor gate 432 adds the quantized value in the count register 450 corresponding to the adder 440 to the first xor logic result and re-assigns the result to the count register 450, thereby completing a count.
In one embodiment, as shown in the above table, when the voltage value is greater than or equal to the fourth threshold voltage or the voltage value is less than the first threshold voltage, the trig values output by the exclusive-or logic circuit 430 are all 000, which indicates that the first threshold voltage and the fourth threshold voltage are not reasonably set. I.e. the voltage value does not fall within the corresponding voltage threshold interval. That is, at this time, the adder 440 may determine that the xor logic result is abnormal, and the adder 440 may report an error through the controller, so that the operator may reset the threshold voltage.
After a count is completed, the reset switch 230 is closed to drain the charge accumulated in the feedback capacitor 220, and the feedback capacitor 220 is reset. At the same time, the reset switch 230 is turned off again, and the amplifier 210 receives the charge again and counts again. And circularly counting in the preset period by adopting the mode until one scanning is finished.
As shown in fig. 6, assume that a scan counts three times for three pulse peaks A, B, C. As can be seen in FIG. 5, the amplitude of the pulse peak A is between Vth4 and Vth3 (corresponding to the E1 level). The amplitude of pulse peak B is between Vth3-Vth2 (corresponding to the E2 level). The amplitude of pulse peak C is between Vth2-Vth1 (corresponding to the E3 level). The final count result of each of the count registers 450 is REG 0-1, REG 1-1, and REG 2-1. As can be seen from the above, the energy detection level in the counting circuit 400 can be set according to actual requirements. Similarly, the number of comparators in the comparison circuit 420, the number of xor gates in the xor logic circuit 430, the adder 440, and the count register 450 may be selected according to actual requirements, and it is only required to ensure that one xor gate corresponds to each of the adjacent comparators, and one xor gate corresponds to each of the adder 440 and the count register 450 in sequence. In one embodiment, the pulse amplitude is between 0-Vth1 with a noise reduction effect.
In one embodiment, the counting device 10 based on the capacitive feedback charge-sensitive amplifying circuit further includes: a switch 500. The switch 500 is connected in series between the detector 100 and the first terminal of the amplifier 210. In one embodiment, the switch 500 may be a semiconductor switch. In one embodiment, the switch 500 may also be a relay switch. In one embodiment, the switch 500 can be controlled to be closed and opened by a controller. The switch 500 may control the connection and disconnection between the detector 100 and the amplifying circuit 200.
Referring to fig. 7, an embodiment of the present application provides a counting system 20, which includes a plurality of counting devices 10 based on a capacitive feedback charge-sensitive amplifying circuit according to any one of the above embodiments and a controller 11. The controller 11 is electrically connected to each of the amplifying circuits 200 and each of the counting circuits 400, respectively. When the counting circuit 400 completes one quantization and counting, the controller 11 controls the amplifying circuit 200 corresponding to the counting circuit 400 to reset and re-receive the charge amount.
In one embodiment, the controller 11 is configured to control the switch 500, the reset switch 230 and the capacitance switch 240 in the amplifying circuit 200 to be turned on and off. After the counting device 10 based on the capacitive feedback charge sensitive amplifier circuit completes one scan, the final counting result of the counting circuit 400 can be obtained through the controller 11. The counting system 20 can realize information interaction with external equipment through the controller 11. The counting system 20 described in this embodiment adopts the above structure, which not only improves the discharge time of the feedback capacitor 220 in the amplifying circuit 200, promotes the counting rate, but also reduces the circuit noise and improves the stability.
In one embodiment, the counting system 20 further comprises a digital-to-analog converter (not shown). The counting system 20 can set the respective threshold voltages within the counting circuit 400 by the digital-to-analog converter.
In summary, according to the present application, the detector 100 receives the X-ray and outputs the amount of charge to the amplifier 210, and the feedback capacitor 220 is used to cooperate with the amplifier 210, so that the voltage value output by the amplifier 210 to the threshold judging circuit 300 is gradually increased. When the voltage value is greater than or equal to the preset voltage threshold, the threshold determination circuit 300 outputs a high level to the counting circuit 400, so as to trigger the counting circuit 400 to quantize and count the voltage value based on the preset delay time in the preset period. And the counting circuit 400 completes one quantization and counting, the reset switch 230 is reset and the amplifier 210 receives the charge amount again. This application adopts above-mentioned structure, not only improves in amplifier circuit 200 feedback capacitor 220's discharge time promotes the count rate, has still reduced circuit noise, improves stability.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (12)
1. A counting device based on a capacitance feedback charge sensitive amplifying circuit is characterized by comprising:
a detector (100) for receiving X-rays and outputting a charge amount related to an energy of the X-rays;
an amplifying circuit (200) for outputting a corresponding voltage value according to the amount of charge, an input terminal of the amplifying circuit (200) being connected to an output terminal of the detector (100), the amplifying circuit (200) comprising an amplifier (210) and a feedback capacitor (220), the feedback capacitor (220) being connected in parallel with the amplifier (210);
the input end of the threshold judging circuit (300) is electrically connected with the output end of the amplifying circuit (200), and whether a trigger signal is output or not is determined according to the voltage value; and
the counting circuit (400) is used for quantifying and counting the voltage value according to the trigger signal, a first input end of the counting circuit (400) is connected with an output end of the threshold judging circuit (300), and a second input end of the counting circuit (400) is connected with an output end of the amplifying circuit (200).
2. The capacitance feedback charge sensitive amplification circuit-based counting device according to claim 1, wherein the amplification circuit (200) further comprises:
a reset switch (230), wherein a first end of the amplifier (210), a first end of the feedback capacitor (220), and a first end of the reset switch (230) are commonly connected to an output end of the detector (100), a second end of the amplifier (210) is grounded, and an output end of the amplifier (210) is commonly connected to a second end of the feedback capacitor (220), a second end of the reset switch (230), and an input end of the threshold decision circuit (300).
3. The counting device of claim 2, wherein when the counting circuit (400) receives the trigger signal within a predetermined period, the counting circuit (400) quantizes and counts the voltage value based on a predetermined delay time, and when the counting circuit (400) completes one quantization and counting, the amplifying circuit (200) resets and re-receives the charge amount.
4. The capacitance feedback charge sensitive amplification circuit-based counting device according to claim 1, wherein the amplification circuit (200) further comprises:
a capacitive switch (240), a first terminal of the capacitive switch (240) being electrically connected to a second terminal of the feedback capacitor (220), a second terminal of the capacitive switch (240) being electrically connected to a first terminal of the amplifier (210).
5. The counting device based on the capacitive feedback charge-sensitive amplifying circuit as claimed in claim 4, wherein the number of the capacitive switches (240) is the same as the number of the feedback capacitors (220), and the capacitive switches (240) are electrically connected with the feedback capacitors (220) in a one-to-one correspondence.
6. The counting device based on the capacitive feedback charge-sensitive amplification circuit of claim 1, wherein the voltage value output by the amplification circuit (200) is proportional to the amount of charge.
7. The counting device based on the capacitive feedback charge sensitive amplification circuit according to claim 1, wherein the threshold discrimination circuit (300) comprises:
a first comparator (310), wherein a first end of the first comparator (310) is electrically connected with an output end of the amplifying circuit (200), a second end of the first comparator (310) is used for acquiring a preset voltage threshold, and an output end of the first comparator (310) is electrically connected with the counting circuit (400);
the first comparator (310) is configured to compare the voltage value with the preset voltage threshold, and if the voltage value is greater than or equal to the preset voltage threshold, the first comparator (310) outputs the trigger signal to the counting circuit (400).
8. The counting device based on the capacitive feedback charge-sensitive amplification circuit of claim 1, wherein the counting circuit (400) comprises:
the timing driver (410) is electrically connected with the threshold judging circuit (300), and when the timing driver (410) receives the trigger signal, the timing driver (410) starts timing and outputs a driving signal when reaching a preset delay time;
a comparison circuit (420) electrically connected to the output terminals of the timing driver (410) and the amplification circuit (200), respectively, for receiving the voltage value based on the driving signal and outputting a comparison result;
an exclusive-or logic circuit (430) electrically connected to the comparison circuit (420) for obtaining the comparison result and outputting an exclusive-or logic result based on the comparison result;
an adder (440) electrically connected to the timing driver (410) and the exclusive-or logic circuit (430), respectively; and
and the counting register (450) is respectively and electrically connected with the timing driver (410) and the adder (440), the adder (440) performs accumulated counting on the quantized value in the counting register (450) based on the exclusive-or logic result, outputs the current quantized value to the counting register (450) for storage, and when the counting register (450) completes one-time quantization and counting, the amplifying circuit (200) resets and receives the charge amount again.
9. The counting device of claim 8, wherein said comparison circuit (420) comprises at least: a second comparator (421) and a third comparator (422), wherein a first end of the second comparator (421) and a first end of the third comparator (422) are both electrically connected with an output end of the amplifying circuit (200), a second end of the second comparator (421) is used for inputting a first threshold voltage, and a second end of the third comparator (422) is used for inputting a second threshold voltage;
the exclusive-or logic circuit (430) at least comprises an exclusive-or gate (431), a first end of the exclusive-or gate (431) is electrically connected with the output end of the second comparator (421), a second end of the exclusive-or gate (431) is electrically connected with the output end of the third comparator (422), and the output end of the exclusive-or gate (431) is electrically connected with the adder (440);
the second comparator (421) outputs a first comparison result based on the first threshold voltage and the voltage value, the third comparator (422) outputs a second comparison result based on the second threshold voltage and the voltage value, and the exclusive or gate (431) outputs an exclusive or logic result to the adder (440) according to the first comparison result and the second comparison result.
10. The capacitance feedback charge sensitive amplification circuit-based counting device of claim 9, wherein the first threshold voltage and the second threshold voltage are not the same.
11. The counting device based on the capacitive feedback charge-sensitive amplification circuit of claim 1, further comprising:
a switch (500) connected in series between the detector (100) and an input of the amplifying circuit (200).
12. A counting system comprising a plurality of counting devices based on a capacitive feedback charge sensitive amplification circuit as claimed in any one of claims 1 to 10; and
and the controller (11) is respectively and electrically connected with each amplification circuit (200) and each counting circuit (400), and when the counting circuit (400) finishes one-time quantization and counting, the controller (11) controls the amplification circuit (200) corresponding to the counting circuit (400) to reset and receive the charge amount again.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114721029A (en) * | 2022-06-09 | 2022-07-08 | 山东大学 | Gamma photon detector reading electronic system based on inorganic perovskite |
Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102135626A (en) * | 2009-11-26 | 2011-07-27 | 西门子公司 | Circuit arrangement for counting x-ray radiation x-ray quanta by way of quanta-counting detectors, and also an application-specific integrated circuit and an emitter-detector system |
| CN103492906A (en) * | 2011-04-21 | 2014-01-01 | 株式会社电视*** | Calibration device for photon counting radiation detector and calibration method thereof |
| CN103998952A (en) * | 2011-12-19 | 2014-08-20 | 皇家飞利浦有限公司 | X-ray detector |
| CN104220900A (en) * | 2012-03-27 | 2014-12-17 | 皇家飞利浦有限公司 | High flux photon counting detector electronics |
| WO2015058702A1 (en) * | 2013-10-23 | 2015-04-30 | 曹红光 | Photon count-based radiation imaging system, method, and apparatus |
| US20160033654A1 (en) * | 2014-07-30 | 2016-02-04 | Kabushiki Kaisha Toshiba | Photon-counting type x-ray ct apparatus |
| US20160070005A1 (en) * | 2014-06-16 | 2016-03-10 | Kabushiki Kaisha Toshiba | Photon-counting x-ray ct apparatus and photon-counting x-ray diagnostic apparatus |
| CN105593701A (en) * | 2013-09-25 | 2016-05-18 | 模拟技术公司 | Hybrid photon counting data acquisition system |
| CN108351429A (en) * | 2015-10-28 | 2018-07-31 | 皇家飞利浦有限公司 | CT system and CT methods |
| CN110476086A (en) * | 2017-04-06 | 2019-11-19 | 皇家飞利浦有限公司 | Pulse shaper |
| US20200158895A1 (en) * | 2018-11-19 | 2020-05-21 | Prismatic Sensors Ab | X-ray imaging system for phase contrast imaging using photon-counting events |
-
2020
- 2020-09-11 CN CN202010954068.9A patent/CN112149787B/en active Active
Patent Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102135626A (en) * | 2009-11-26 | 2011-07-27 | 西门子公司 | Circuit arrangement for counting x-ray radiation x-ray quanta by way of quanta-counting detectors, and also an application-specific integrated circuit and an emitter-detector system |
| CN103492906A (en) * | 2011-04-21 | 2014-01-01 | 株式会社电视*** | Calibration device for photon counting radiation detector and calibration method thereof |
| CN103998952A (en) * | 2011-12-19 | 2014-08-20 | 皇家飞利浦有限公司 | X-ray detector |
| CN104220900A (en) * | 2012-03-27 | 2014-12-17 | 皇家飞利浦有限公司 | High flux photon counting detector electronics |
| CN105593701A (en) * | 2013-09-25 | 2016-05-18 | 模拟技术公司 | Hybrid photon counting data acquisition system |
| WO2015058702A1 (en) * | 2013-10-23 | 2015-04-30 | 曹红光 | Photon count-based radiation imaging system, method, and apparatus |
| US20160070005A1 (en) * | 2014-06-16 | 2016-03-10 | Kabushiki Kaisha Toshiba | Photon-counting x-ray ct apparatus and photon-counting x-ray diagnostic apparatus |
| US20160033654A1 (en) * | 2014-07-30 | 2016-02-04 | Kabushiki Kaisha Toshiba | Photon-counting type x-ray ct apparatus |
| CN108351429A (en) * | 2015-10-28 | 2018-07-31 | 皇家飞利浦有限公司 | CT system and CT methods |
| CN110476086A (en) * | 2017-04-06 | 2019-11-19 | 皇家飞利浦有限公司 | Pulse shaper |
| US20200158895A1 (en) * | 2018-11-19 | 2020-05-21 | Prismatic Sensors Ab | X-ray imaging system for phase contrast imaging using photon-counting events |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114721029A (en) * | 2022-06-09 | 2022-07-08 | 山东大学 | Gamma photon detector reading electronic system based on inorganic perovskite |
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