Photon detection unit, imaging detection array, X-ray imaging detection module, detector and detection system

Abstract

The present disclosure relates to a photon detection unit, an imaging detection array, an X-ray imaging detection module, a detector, and a detection system. The unit includes: a photodetection element for outputting a current signal corresponding to the energy of an incident photon; a charge-sensitive preamplifier for converting and amplifying the current signal into a voltage signal; a comparator for outputting a control signal when the voltage value of the voltage signal is higher than a reference voltage value; a charge pump for injecting a specified amount of charge into the input terminal of the charge-sensitive preamplifier in response to the control signal output by the comparator; a counter for counting the number of times the comparator outputs the control signal within a single frame time; and a voltage sampling circuit for sampling the voltage value of the voltage signal output by the charge-sensitive preamplifier at the end of the single frame time. Thus, the dynamic range of X-ray imaging detection can be increased while ensuring a high signal-to-noise ratio and a high readout frame rate, thereby improving the quality of X-ray imaging.

Description

Technical Field

[0001] The present disclosure relates to the field of X-ray imaging detection, and in particular to a photon detection unit, an imaging detection array, an X-ray imaging detection module, a detector, and a detection system. Background Art

[0002] X-ray imaging systems require the detection of two-dimensional X-ray intensity distributions to reconstruct sample images and obtain structural information. Therefore, X-ray imaging detectors are a key component in determining the final image quality. With the continuous improvement of imaging requirements, typical X-ray imaging detectors are divided into amorphous silicon detectors manufactured using thin-film transistors (TFTs) and CMOS flat-panel imaging detectors manufactured using complementary metal oxide semiconductor (CMOS) technology. Currently, CMOS flat-panel imaging detectors are widely used in fields such as medical testing, computed tomography, and industrial flaw detection. X-ray imaging detectors have gradually evolved from early X-ray film detectors with poor real-time performance and low imaging quality to current TFT- and CMOS-based flat-panel detectors with real-time output, low cost, and high imaging quality. Compared to TFTs, CMOS flat-panel imaging detectors offer advantages such as low power consumption, low cost, radiation resistance, fast processing speed, low noise, and high integration, making them the mainstream development direction of X-ray imaging detectors.

[0003] A CMOS flat-panel imaging detector module consists of two components: the detector and the readout circuit. The detector performs photoelectric conversion, generating a charge proportional to the incident X-ray intensity. The readout circuit converts this charge into a voltage using a charge-sensitive preamplifier. After signal processing, the analog voltage is quantized into a digital output. The detector is typically divided into array elements, each called a detector pixel. Because each detector pixel requires independent readout, the readout circuit must be implemented using integrated circuit technology. Furthermore, in active CMOS flat-panel imaging detectors, the detector and readout circuitry are typically integrated on the same silicon wafer.

[0004] In actual detection scenarios, CMOS flat-panel imaging detectors may experience both overexposure and underexposure due to insufficient dynamic range. This results in a loss of X-ray imaging information, hindering the reconstruction of the detected object's structure. Therefore, dynamic range has become a key performance parameter for CMOS flat-panel imaging detectors. The dynamic range of a CMOS flat-panel imaging detector can be defined as the ratio of maximum signal charge to noise, where maximum signal charge can be defined as the maximum charge that can be captured by a single detector pixel within a single frame.

[0005] A variety of high dynamic range (HDR) technologies have been reported to improve the dynamic range of CMOS flat-panel imaging detectors, such as multiple exposure, dual conversion gain, logarithmic response, and lateral overflow integration capacitors (LOFIC). While these high dynamic range technologies can effectively expand the dynamic range of X-ray imaging detection, they can also lead to reduced signal-to-noise ratio, fill factor, full well capacity, and readout frame rate, resulting in decreased X-ray imaging quality. Therefore, achieving high dynamic range X-ray imaging technology while maintaining X-ray imaging quality is an urgent issue. Summary of the Invention

[0006] In view of this, the present disclosure proposes a photon detection unit, an imaging detection array, an X-ray imaging detection module, a detector and a detection system, which can increase the dynamic range of X-ray imaging detection while ensuring a high signal-to-noise ratio and a high readout frame rate, thereby improving the quality of X-ray imaging.

[0007] According to one aspect of the present disclosure, there is provided a photon detection unit comprising: a photodetection element, a charge-sensitive preamplifier, a comparator, a charge pump, a counter, and a voltage sampling circuit;

[0008] Wherein, the photoelectric detection element is used to output a current signal corresponding to the energy of the incident photon to the input end of the charge-sensitive preamplifier;

[0009] The charge-sensitive preamplifier is used to convert and amplify the current signal output by the photoelectric detection element into a voltage signal;

[0010] The comparator is used to compare the voltage value of the voltage signal output by the charge-sensitive preamplifier with a reference voltage value, and output a control signal when the voltage value of the voltage signal output by the charge-sensitive preamplifier is higher than the reference voltage value;

[0011] The charge pump is used to inject a specified amount of charge into the input terminal of the charge-sensitive preamplifier in response to the control signal output by the comparator to offset the current input by the photodetection element, thereby restoring the voltage value of the voltage signal output by the charge-sensitive preamplifier to a preset voltage value, wherein the preset voltage value is less than the reference voltage value;

[0012] The counter is used to count the number of times the comparator outputs the control signal within a single frame time, and output a counting signal, wherein the counting signal represents the total number of times the comparator outputs the control signal within the single frame time;

[0013] The voltage sampling circuit is used to sample the voltage value of the voltage signal output by the charge-sensitive preamplifier at the end of a single frame time, and output a sampling signal, wherein the sampling signal represents the voltage sampling value of the voltage signal output by the charge-sensitive preamplifier at the end of a single frame time;

[0014] The counting signal and the sampling signal are used to determine the accumulated charge on the photoelectric detection element within a single frame time, and the accumulated charge is used to determine the intensity of incident photons.

[0015] In one possible implementation, the photon detection unit also includes: a first source follower connected to the output end of the counter, used to isolate the counting signal output by the counter; and a second source follower connected to the output end of the voltage sampling circuit, used to isolate the sampling signal output by the voltage sampling circuit.

[0016] In a possible implementation, the photon detection unit further includes: a reset switch circuit, configured to reset the charge-sensitive preamplifier and the photodetection element at the beginning of a single frame time.

[0017] In a possible implementation, the photodetection element includes a photodiode; and the voltage sampling circuit includes a correlated double sampling circuit.

[0018] According to another aspect of the present disclosure, an imaging detection array is provided, comprising an array composed of a plurality of the aforementioned photon detection units.

[0019] According to another aspect of the present disclosure, there is provided an X-ray imaging detection module, comprising:

[0020] X-ray scintillator, used to generate photons after interacting with incident X-rays; and

[0021] The imaging detection array is used to detect the photons generated by the X-ray scintillator and output an analog detection signal; wherein the analog detection signal includes the detection signal output by each photon detection unit in the imaging detection array, and the detection signal includes a counting signal and a sampling signal.

[0022] According to another aspect of the present disclosure, there is provided an X-ray imaging detector, comprising:

[0023] The X-ray imaging detection module; and

[0024] The readout circuit module is used to process the analog detection signal output by the imaging detection array in the X-ray imaging detection module into a digital detection signal and output it to the outside of the chip.

[0025] In a possible implementation, the imaging detection array in the X-ray imaging detection module and the readout circuit module are integrated on the same chip.

[0026] According to another aspect of the present disclosure, there is provided an X-ray imaging detection system, comprising:

[0027] The X-ray imaging detector; and

[0028] The host computer is used to generate an X-ray imaging result according to the digital detection signal output by the X-ray imaging detector, wherein the X-ray imaging result represents a two-dimensional intensity distribution diagram of the incident X-ray.

[0029] In one possible implementation, the digital detection signal represents the total number of times output by the counter in each photon detection unit and the voltage sampling value output by the voltage sampling circuit; wherein, generating the X-ray imaging result based on the digital detection signal output by the X-ray imaging detector includes: for the total number of times output by the counter in any photon detection unit and the voltage sampling value output by the voltage sampling circuit, adding the charge corresponding to the voltage sampling value to the product of the total number of times and the specified charge amount to obtain the cumulative charge of the photon detection unit within a single frame time; generating the X-ray imaging result based on the cumulative charge of each photon detection unit in the imaging detection array in the X-ray imaging detector within a single frame time.

[0030] According to various aspects of the present disclosure, by integrating circuit structures such as a photoelectric detection element, a charge-sensitive preamplifier, a comparator, a charge pump, a counter, and a voltage sampling circuit in a photon detection unit, it is possible to output a control signal to the charge pump after the comparator compares that the voltage at the output end of the charge-sensitive preamplifier reaches a set reference voltage value, thereby controlling the charge pump to inject a specified amount of charge into the input end of the charge-sensitive preamplifier to neutralize the current from the photoelectric detection element, thereby increasing the maximum amount of charge that can be detected by a single photon detection unit within a single frame time, effectively expanding the dynamic range of photon detection, and at the same time having lower noise introduction. In some exemplary applications, the X-ray imaging detection module, detector, and detection system implemented by the photon detection unit can effectively realize X-ray imaging detection with a large dynamic range, and have the characteristics of high signal-to-noise ratio, high readout frame rate, etc.

[0031] Further features and aspects of the present disclosure will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments, features, and aspects of the disclosure and, together with the description, serve to explain the principles of the disclosure.

[0033] Figure 1 A schematic structural diagram of a photon detection unit according to an embodiment of the present disclosure is shown.

[0034] Figure 2 A schematic structural diagram of another photon detection unit according to an embodiment of the present disclosure is shown.

[0035] Figure 3 A schematic structural diagram of another photon detection unit according to an embodiment of the present disclosure is shown.

[0036] Figure 4 A schematic diagram of the circuit structure of a photon detection unit according to an embodiment of the present disclosure is shown.

[0037] Figure 5 A schematic diagram of an imaging detection array according to an embodiment of the present disclosure is shown.

[0038] Figure 6 A schematic diagram of an X-ray imaging detection module according to an embodiment of the present disclosure is shown.

[0039] Figure 7 A schematic diagram of an X-ray imaging detector according to an embodiment of the present disclosure is shown.

[0040] Figure 8 A schematic structural diagram of a readout chip according to an embodiment of the present disclosure is shown.

[0041] Figure 9 A schematic diagram of an X-ray imaging detection system according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0042] Various exemplary embodiments, features, and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0043] As used herein, the terms "comprises," "comprising," "having," or variations thereof are open ended and include one or more stated features, integers, elements, steps, parts, or functions, but do not preclude the presence or addition of one or more other features, integers, elements, steps, parts, functions, or groups thereof.

[0044] When an element is referred to as being "connected," "coupled," "responsive" or variations thereof to another element, it can be directly connected, coupled or responsive to the other element or intervening elements may be present.

[0045] Although the terms first, second, third, etc. may be used herein to describe various elements / operations, these elements / operations should not be limited by these terms. These terms are only used to distinguish one element / operation from another element / operation. Therefore, without departing from the teachings of the present invention, the first element / operation in some embodiments may be referred to as the second element / operation in other embodiments.

[0046] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0047] In addition, numerous specific details are provided in the following detailed description to better illustrate the present disclosure. Those skilled in the art will appreciate that the present disclosure can be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art are not described in detail in order to highlight the main points of the present disclosure.

[0048] Figure 1 FIG. 1 is a schematic structural diagram of a photon detection unit according to an embodiment of the present disclosure. Figure 1 As shown, the photon detection unit 00 includes:

[0049] A photodetection element 101, a charge-sensitive preamplifier 102, a comparator 103, a charge pump 104, a counter 105 and a voltage sampling circuit 106; wherein the photodetection element 101 is connected to the input end of the charge-sensitive preamplifier 102, the output end of the charge-sensitive preamplifier 102 is connected to one input end of the comparator 103, the other input end of the comparator 103 is connected to the reference voltage Vref, the output end of the charge-sensitive preamplifier 102 is also connected to the input end of the voltage sampling circuit 106, the output end of the comparator 103 is connected to the input end of the charge pump 104, the output end of the charge pump 104 is connected to the input end of the charge-sensitive preamplifier 102, and the output end of the comparator 103 is also connected to the input end of the counter 105.

[0050] The photodetection element 101 is used to output a current signal corresponding to the energy of the incident photon to the input end of the charge-sensitive preamplifier 102;

[0051] The charge-sensitive preamplifier 102 is used to convert and amplify the current signal output by the photodetection element 101 into a voltage signal;

[0052] The comparator 103 is used to compare the voltage value V of the voltage signal output by the charge-sensitive preamplifier 102 with the reference voltage value Vref, and output a control signal when the voltage value of the voltage signal output by the charge-sensitive preamplifier 102 is higher than the reference voltage value;

[0053] The charge pump 104 is configured to inject a specified amount of charge into the input terminal of the charge-sensitive preamplifier 102 in response to the control signal output by the comparator 103 to offset the current input by the photodetection element 101, thereby restoring the voltage value V of the voltage signal output by the charge-sensitive preamplifier 102 to a preset voltage value (e.g., 0V), which is lower than the reference voltage value.

[0054] The counter 105 is used to count the number of times the comparator 103 outputs the control signal within a single frame time, and output a count signal Count, where the count signal Count represents the total number of times the comparator 103 outputs the control signal within a single frame time;

[0055] The voltage sampling circuit 106 is used to sample the voltage value of the voltage signal output by the charge-sensitive preamplifier 101 at the end of a single frame time, and output a sampling signal Vsamp, wherein the sampling signal Vsamp represents the voltage sampling value of the output end of the charge-sensitive preamplifier 102 at the end of a single frame time;

[0056] The counting signal Count and the sampling signal Vsamp are used to determine the accumulated charge on the photoelectric detection element within a single frame time, and the accumulated charge is used to determine the intensity of incident photons.

[0057] In practical applications, the photodetection element 101 can be, for example, a photodiode. Of course, other photodetection elements known in the art (such as a photomultiplier tube, etc.) can also be used, and this is not limited to the embodiments of the present disclosure. The charge sensitive preamplifier 102 can be any charge sensitive preamplifier (CSP) known in the art, and this is not limited to the embodiments of the present disclosure. The comparator 103 can be, for example, a single limit comparator, an open-loop comparator, a differential comparator, or any other comparator known in the art, and this is not limited to the embodiments of the present disclosure. The charge pump 104 can be any charge pump known in the art (Charge Pump), and this is not limited to the embodiments of the present disclosure. The counter 105 can be, for example, a binary counter, and of course, other counters known in the art can also be used, and this is not limited to the embodiments of the present disclosure. The voltage sampling circuit 104 can be, for example, a correlated double sampling (CDS) circuit, and of course, other voltage sampling circuits known in the art can also be used, and this is not limited to the embodiments of the present disclosure.

[0058] In practical applications, those skilled in the art can customize the size of the reference voltage value input to the other end of the comparator 103 and the size of the preset voltage value according to actual needs such as the full well capacity of the photodetection element and the size of the capacitor used to accumulate charge in the charge-sensitive preamplifier. They can then set the size of the specified charge amount injected by the charge pump 104 into the input end of the charge-sensitive preamplifier 102 each time based on the set reference voltage value and the size of the preset voltage value, and ensure that the charge injected by the charge pump 104 is opposite to the charge input by the photodetection element 101. Therefore, the embodiments of the present disclosure do not limit the specific sizes of the reference voltage value, the preset voltage value and the specified charge amount.

[0059] Taking the case where the photoelectric detection element 101 adopts a photodiode, the voltage sampling circuit 104 adopts a CDS circuit, and the incident photon is a photon generated by the interaction between X-rays and a scintillator (such as cesium iodide), the working principle of the above-mentioned photon detection unit 00 is introduced as follows: the incident X-rays interact with the scintillator to generate photons, and the photons deposit energy in the photodiode 101, generating electron-hole pairs, which move toward the two poles under the action of the electric field and are collected. The current signal generated by the movement of the charge will be output to the input end of the charge-sensitive preamplifier 102, and will be converted and amplified into a voltage signal after passing through the charge-sensitive preamplifier 102. When the comparator 103 compares that the voltage value of the voltage signal output by the charge-sensitive preamplifier 102 exceeds a set threshold value (that is, exceeds the reference voltage value Vref), a control signal is output to the charge pump 104, so that the charge pump 104 circuit is triggered and starts to inject a specified amount of charge into the input end of the charge-sensitive preamplifier 102 to offset the current input by the photodiode 101 to the charge-sensitive preamplifier 102, so that the voltage value of the voltage signal output by the charge-sensitive preamplifier 102 is restored to the preset voltage value. At the same time, the number of times the charge pump 104 is triggered within a single frame time (that is, the number of times the comparator 103 outputs the control signal) will also be recorded by the counter 105 and the counting signal count will be output. For example, the control signal output by the comparator 103 can be a pulse signal, and the counter 105 can count the number of pulses output by the comparator 103 within a single frame time. At the same time, the voltage value output by the charge-sensitive preamplifier 102 can be sampled by the CDS circuit and a sampling signal Vsamp is output at the end of the single frame time. The CDS circuit can sample the voltage value of the voltage signal output by the charge-sensitive preamplifier at the beginning and end of the single frame time, respectively, and calculate the difference between the voltage value sampled at the end of the single frame time and the voltage value sampled at the beginning of the single frame time as the voltage sampling value at the output of the charge-sensitive preamplifier at the end of the single frame time. Therefore, using the CDS circuit for voltage sampling can reduce the impact of reset noise at the beginning of the single frame time and improve the accuracy of the sampled voltage value. Of course, the voltage sampling circuit 106 can also be used to only sample the voltage value at the output of the charge-sensitive preamplifier at the end of the single frame time as the final voltage sampling value, which is not limited in the embodiment of the present disclosure. Furthermore, the accumulated integrated charge on the photodiode within the single frame time can be calculated based on the counting signal and the sampling signal collected at the end of the single frame time, which is equivalent to realizing the conversion from optical signal to electrical signal.

[0060] Based on the above working principle, it can be known that in order to realize the technical route of the large dynamic range signal processing circuit, the embodiment of the present disclosure is mainly optimized from the pixel circuit (that is, the photon detection unit circuit). As mentioned above, the dynamic range of the CMOS flat-panel imaging detector is defined as the ratio of the maximum signal charge to the noise. The maximum charge that can be detected by the existing detector pixel is mainly limited by the full well capacity of the photodiode. This is because the full well capacity is proportional to the pixel area, and the pixel area is related to the specific application scenario and hardware design of the detector. Therefore, if the pixel area of ​​the detector pixel is certain, the maximum charge that the detector pixel can detect is certain, so that the dynamic range of the detector pixel is limited to the full well capacity of the photodiode. Therefore, a photon detection unit proposed in the embodiment of the present disclosure can adopt a reset extension scheme at the circuit level to increase the maximum signal charge of a single photon detection unit (that is, to increase the maximum charge that can be collected in a single frame).

[0061] Specifically, after the voltage value at the output end of the charge-sensitive preamplifier 102 reaches the reference voltage value, the comparator 103 outputs a control signal to the charge pump 104, controlling the charge pump 104 to inject charge into the input end of the charge-sensitive preamplifier 102 to neutralize the charge input from the photodiode 101, thereby increasing the maximum signal charge amount of a single photon detection unit. For example, assuming that the full well capacity of the photodiode is 1 (that is, the maximum charge amount that the photodiode can accommodate is 1), and the reference voltage value is the voltage value at the output end of the charge-sensitive preamplifier when the charge amount in the photodiode reaches 3 / 4, then within a single frame time, whenever the charge amount in the photodiode reaches 3 / 4, the charge pump will inject an opposite charge (such as a negative charge) into the input end of the charge-sensitive preamplifier to neutralize the current (such as a positive charge) input from the photodiode 101, thereby increasing the charge-sensitive preamplifier 1 The voltage at the output terminal of the photodiode 02 decreases to a preset voltage value until the charge in the photodiode 101 reaches 3 / 4 again. The above process repeats within a single frame time. If it occurs four times and the charge in the photodiode is 1 / 2 at the end of the single frame time (the charge in the photodiode at this time can be converted by collecting the voltage value at the output terminal of the charge-sensitive preamplifier 102), then the photon detection unit can collect a charge of 3 / 4×4+1 / 2=3.5 in a single frame time. Compared with the original full well capacity of the photodiode of 1, the maximum charge that can be collected by a single photon detection unit in a single frame time can be greatly increased. Therefore, when using the photon detection unit of the embodiment of the present disclosure for X-ray imaging detection, not only will the problems of reduced full well capacity and fill factor be avoided, but a large dynamic range of X-ray imaging detection can also be achieved while ensuring a high signal-to-noise ratio and a high readout frame rate. In addition, the signal output method of the single photon detection unit using the output of the charge pump trigger count (i.e., the output count signal) and the sampling signal of the correlated double sampling circuit can also greatly reduce the dynamic range requirements of the related column-level readout circuit.

[0062] In a possible implementation, in order to facilitate the photon detection unit to perform periodic detection, such as Figure 2As shown, the photon detection unit 00 may further include a reset switch circuit 107 for resetting the charge-sensitive preamplifier 102 and the photodetection element 101 at the beginning of a single frame time. For example, the charge-sensitive preamplifier 102 and the photodetection element 101 may be reset by controlling the reset switch circuit 107 to be closed and opened at the beginning of a single frame time. Among them, when the reset switch 107 is closed, the circuit where the reset switch 107 is located is turned on, so that the charge in the photodetection element 101 and the charge-sensitive preamplifier 102 is released, thereby resetting the photodetection element 101 and the charge-sensitive preamplifier 102. At this time, the voltage sampling circuit 106 (i.e., the related bidirectional circuit) can be controlled to collect the voltage at the output end of the charge-sensitive preamplifier 102, thereby obtaining the voltage value sampled at the beginning of the single frame time. Furthermore, as mentioned above, the related bidirectional circuit can also sample the voltage value at the output end of the charge-sensitive preamplifier 102 at the end of the single frame time, and calculate the difference between the voltage value sampled at the end of the single frame time and the voltage value sampled at the beginning of the single frame time as the voltage sampling value of the output end of the charge-sensitive preamplifier at the end of the single frame time. This can reduce the influence of the reset noise at the beginning of the single frame time (i.e., the noise generated when resetting using the reset switch), thereby improving the accuracy of the sampled voltage value.

[0063] In practical applications, the start and end of a single frame time can be controlled by an external logic circuit via a control signal. The disclosed embodiments do not limit the control method or duration of a single frame time. Furthermore, for example, an external clock can be used to control the operating timing of various components in the photon detection unit. For example, the counting operation of a counter, the sampling operation of a voltage sampling circuit, and the timing of the closing and opening operations of the reset switch can be controlled, thereby enabling various components in the photon detection unit to operate under a unified clock cycle. The disclosed embodiments do not limit the control method for the operating timing of various components in the photon detection unit.

[0064] In a possible implementation, in order to ensure that the counter outputs a counting signal and the voltage sampling circuit outputs a sampling signal in a stable manner, a source follower can be used to isolate the counter and the voltage sampling circuit from the external circuit. Figure 3As shown, the photon detection unit 00 further includes: a first source follower 108 connected to the output of the counter 105 for isolating the count signal output by the counter; and a second source follower 109 connected to the output of the voltage sampling circuit 106 for isolating the sampling signal output by the voltage sampling circuit 106. In practical applications, any source follower known in the art can be used as the first source follower and the second source follower, and this embodiment of the present disclosure is not limited to this.

[0065] based on Figure 3 The schematic diagram of the structure of the photon detection unit 00 is shown, and the embodiment of the present disclosure also provides Figure 4 A schematic diagram of the circuit structure of a photon detection unit 00 is shown, as shown in FIG. Figure 4 As shown, the cathode of the photodiode 101 is connected to the “-” input terminal of the charge-sensitive preamplifier 102, the output terminal of the charge-sensitive preamplifier 102 is connected to the “+” input terminal of the comparator, the “-” input terminal of the comparator is connected to the reference voltage Vref, the output terminal of the comparator is connected to the charge pump 106, the output terminal of the charge pump 106 is connected to the “-” input terminal of the charge-sensitive preamplifier 102, the output terminal of the comparator 103 is also connected to the counter 105, the output terminal of the counter 105 is connected to the first source follower 108, the output terminal of the charge-sensitive preamplifier 102 is also connected to the correlated double sampling circuit CDS (106), and the output terminal of the CDS (106) is connected to the second source follower 108.

[0066] It should be noted that the above Figure 4 The circuit structure shown is only an exemplary simplified circuit structure. In practice, the circuit structure within or between the components in the photon detection unit 00 may be more complex. In particular, Figure 4 The charge-sensitive preamplifier 102 shown in the figure is only a simplified circuit structure. In fact, the internal circuit structure of the charge-sensitive preamplifier 102 can be more complex. Those skilled in the art can design and develop the specific circuit structure of each circuit part in the photon detection unit 00 based on the guidance of the embodiment of the present disclosure. The embodiment of the present disclosure does not limit this.

[0067] According to the photon detection unit of the embodiment of the present disclosure, by integrating circuit structures such as a photoelectric detection element, a charge-sensitive preamplifier, a comparator, a charge pump, a counter, and a voltage sampling circuit in the photon detection unit, it is possible to output a control signal to the charge pump after the comparator compares that the voltage at the output end of the charge-sensitive preamplifier reaches a set reference voltage value, and control the charge pump to inject a specified amount of charge into the input end of the charge-sensitive preamplifier to neutralize the current from the photoelectric detection element, thereby increasing the maximum amount of charge that a single photon detection unit can detect within a single frame time, effectively expanding the dynamic range of photon detection, and at the same time having lower noise introduction, so that the photon detection unit can be used to achieve X-ray imaging detection with a large dynamic range, and has the characteristics of high signal-to-noise ratio, high readout frame rate, etc.

[0068] Based on the photon detection unit proposed in the above embodiment of the present disclosure, the embodiment of the present disclosure further provides an imaging detection array 200, comprising an array composed of a plurality of the above photon detection units 00. For example, Figure 5 An imaging detection array 200 is shown, comprising an array composed of 4×4 photon detection units 00 . The 4×4 photon detection units 00 may be arranged on a substrate, for example.

[0069] It should be noted that Figure 5 This is only an exemplary possible implementation method provided by the embodiment of the present disclosure. In fact, those skilled in the art can set the number of units (i.e., the number of pixels), layout and hardware structure in the imaging detection array according to actual needs, and the embodiment of the present disclosure does not limit this.

[0070] Based on the above imaging detection array, the embodiment of the present disclosure provides Figure 6 A schematic diagram of an X-ray imaging detection module 300 is shown, as shown in FIG. Figure 6 As shown, the X-ray imaging detection module 300 may include:

[0071] X-ray scintillator 330, used to generate photons after interacting with incident X-rays; and

[0072] Imaging detection array 200 (such as Figure 5 The imaging detection array 200 is used to detect photons generated by the X-ray scintillator 330 and output analog detection signals;

[0073] The analog detection signal includes the detection signal detected by each photon detection unit in the imaging detection array, and the detection signal includes a counting signal and a sampling signal.

[0074] In practical applications, the X-ray scintillator 330 and the imaging detection array 200 can be used Figure 6The non-coupled structure shown (i.e., the entire X-ray scintillator 330 is located on one side of the imaging detection array 200 facing the incident direction of the X-ray), or the photon detection unit 00 in the imaging detection array 200 can be coupled with the X-ray scintillator 330. The X-ray scintillator 330 in this coupling mode can include multiple scintillator units, which are arranged at the intervals between the photon detection units. This embodiment of the present disclosure does not limit this.

[0075] It should be noted that the embodiment of the present disclosure does not limit the material type of the X-ray scintillator. Figure 6 The X-ray imaging detection module shown is only an exemplary possible implementation method provided by the embodiment of the present disclosure. In fact, those skilled in the art can customize the position relationship, size, quantity, structural layout, etc. of the X-ray scintillator and imaging detection array according to actual needs, and the embodiment of the present disclosure does not limit this.

[0076] Based on the above X-ray imaging detection module, the embodiment of the present disclosure also provides Figure 7 A schematic diagram of an X-ray imaging detector 400 is shown, as shown in FIG. Figure 7 As shown, the X-ray imaging detector 400 includes:

[0077] X-ray imaging detection module 300 (such as Figure 6 X-ray imaging detection module 300 shown); and,

[0078] The readout circuit module 440 is used to process the analog detection signal output by the imaging detection array 200 in the X-ray imaging detection module 300 into a digital detection signal and output it to the outside of the chip.

[0079] In practical applications, the imaging detector array 200 and the readout circuit module 440 in the X-ray imaging detection module 300 can be integrated into the same chip. The chip integrating the imaging detector array and the readout circuit module 440 in the X-ray imaging detection module 300 can be referred to as a readout chip, thereby enabling efficient signal readout. The readout circuit module 440 can employ a readout circuit known in the art for use in CMOS flat-panel imaging detectors. Alternatively, a custom readout circuit module can be designed, as long as the desired functionality is achieved. This is not a limitation of the present disclosure.

[0080] For example, Figure 8 A schematic diagram of the structure of a readout chip is shown. Figure 8 As shown, the readout chip integrates an imaging detection array and a readout circuit module, and the readout circuit module includes:

[0081] A clock control circuit, used to control the working sequence of each circuit in the readout circuit module;

[0082] A row address decoder is used to decode the received row address signal under the control of the clock control circuit to obtain the row to be read out in the imaging detection array indicated by the row address signal;

[0083] A row driver, configured to drive the photon detection unit corresponding to the row decoded by the row address decoder under the control of the clock control circuit, so that the photon detection unit in the row outputs a detection signal;

[0084] A column-level analog-to-digital converter (ADC) circuit is used to simultaneously convert detection signals output by a single row of photon detection units into digital signals under the control of a clock control circuit;

[0085] A multiplexing circuit is used to combine the digital signals simultaneously output by the column-level analog-to-digital converter circuits under the timing control of the clock control circuit to obtain a digital detection signal;

[0086] The output driving circuit is used to drive the digital detection signal combined by the multiplexing circuit to the external interface, so as to output the digital detection signal to the outside of the chip through the external interface.

[0087] like Figure 8 As shown, the clock control circuit can control the timing of the entire readout chip. The clock control circuit can receive external clock signals and trigger synchronization signals to generate the necessary timing signals and control signals to synchronize and coordinate the operating timing of each circuit module in the entire readout chip. The row address decoder and row driver circuit can control the signal readout of a single row of photon detection units. The row address signal received by the row address decoder can be a signal sent by the clock control circuit, or of course, a signal sent by other external logic control units to indicate the current row to be read out. This is not limited in the present embodiment. The column-level analog-to-digital converter circuit may include multiple columns of analog-to-digital converters (ADCs), with one analog-to-digital converter placed in each column corresponding to a column of photon detection units, for converting the detection signals output by the photon detection units in that column. During signal readout, the detection signals output by each row of photon detection units are simultaneously fed into the column-level ADC circuit for conversion. The converted digital signals are processed by a multiplexer to obtain digital detection signals, which are then output to the outside of the chip through an output driver circuit. The external interface may be an interface for external signal transmission, such as a data bus interface, so that the data detection signal can be output to the outside via the data bus. Furthermore, the imaging detection array 200, the column-level ADC circuit, and the multiplexing circuit in the X-ray imaging detection module 300 may be powered by an external power supply to achieve X-ray imaging detection.

[0088] It should be noted that the above Figure 8The readout circuit module shown in the figure is a possible implementation method provided by the embodiment of the present disclosure. In fact, those skilled in the art can customize the specific circuit structure of the readout circuit under the guidance of the embodiment of the present disclosure, and the embodiment of the present disclosure does not limit this.

[0089] In actual applications, in addition to the X-ray imaging detection module 300 and the readout circuit module 440, the X-ray imaging detector 400 may also include other hardware modules required to implement X-ray imaging detection. For example, the X-ray imaging detector 400 may also include a power supply module for powering circuit modules such as the X-ray imaging detection module 300 and the readout circuit module 440. It may also include a clock module for providing a clock signal to the X-ray imaging detection module 300 and the readout circuit module 440 to coordinate and synchronize the operations of various modules, etc., and the embodiments of the present disclosure do not limit this.

[0090] It should be noted that the X-ray imaging detectors proposed in the above-mentioned embodiments of the present disclosure are some exemplary possible implementation methods provided by the embodiments of the present disclosure. In fact, those skilled in the art can customize the internal structure, hardware modules included, etc. of the X-ray imaging detector according to actual needs, and the embodiments of the present disclosure do not limit this.

[0091] According to the X-ray imaging detector of the embodiment of the present disclosure, a large dynamic range CMOS flat-panel imaging detector for use in the field of X-ray imaging can be realized, which has the characteristics of high signal-to-noise ratio, high readout frame rate, and large dynamic range. It helps to solve the difficulties encountered by traditional CMOS flat-panel imaging detectors and improve the quality of X-ray imaging.

[0092] Based on the above X-ray imaging detection system, the present disclosure also provides the following Figure 9 A schematic diagram of an X-ray imaging detection system is shown in FIG. Figure 9 As shown, the system includes:

[0093] X-ray imaging detector 400; and

[0094] The host computer 500 is used to generate an X-ray imaging result based on the digital detection signal output by the X-ray imaging detector 400. The X-ray imaging result represents a two-dimensional intensity distribution diagram of the incident X-rays.

[0095] In practical applications, the X-ray imaging detector 400 and the host computer 500 may transmit signals via a data bus, for example. Of course, other known data transmission methods in the art may also be used, which is not limited in the embodiments of the present disclosure.

[0096] It should be understood that the digital detection signal output by the X-ray imaging detector 400 may include a digital signal converted from a counting signal and a sampling signal output by each photon detection unit in the imaging detection array, that is, the digital detection signal represents the total number of times output by the counter in each photon detection unit and the voltage sampling value output by the voltage sampling circuit. Then, by analyzing the digital detection signal, the total number of times output by the counter in each photon detection unit in the imaging detection array and the voltage sampling value output by the voltage sampling circuit can be obtained, and then the accumulated charge in each photon detection unit can be calculated. Based on the correspondence between the known accumulated charge and the photon intensity generated by the X-ray (for example, the correspondence can be obtained in advance through experimental testing combined with theoretical analysis), a two-dimensional intensity distribution diagram of the X-ray is generated.

[0097] Specifically, generating an X-ray imaging result according to the digital detection signal output by the X-ray imaging detector may include:

[0098] For the total number of times output by the counter in any photon detection unit and the voltage sampling value output by the voltage sampling circuit, the product of the total number of times and the specified charge amount is added to the charge amount corresponding to the voltage sampling value to obtain the cumulative charge amount of the photon detection unit within a single frame time;

[0099] The X-ray imaging result is generated according to the accumulated charge of each photon detection unit in the imaging detection array in the X-ray imaging detector within a single frame time.

[0100] As described above, the specified charge amount is the charge amount injected by the charge pump into the charge-sensitive preamplifier each time. The total number of times output by the counter can represent the number of times the charge pump is triggered within a single frame time (i.e., the number of times charge is injected into the charge-sensitive preamplifier). The voltage sampling value output by the voltage sampling circuit can indicate the voltage value at the output end of the charge-sensitive preamplifier at the end of the single frame time. The voltage value at this time can be used to infer the amount of charge remaining in the photodetection element (such as a photodiode) at the end of the single frame time. For example, the voltage sampling value can be multiplied by the size of the capacitor used to accumulate charge in the charge-sensitive preamplifier to obtain the amount of charge remaining in the photodetection element at the end of the single frame time (i.e., the charge amount corresponding to the voltage sampling value). Therefore, the product of the total number of times the charge pump injects the specified charge amount into the charge-sensitive preamplifier and the specified charge amount can be added to the charge amount corresponding to the voltage sampling value to obtain the cumulative charge amount of the photon detection unit within the single frame time (i.e., the accumulated integrated charge on the photodiode in the photon detection unit).

[0101] Furthermore, after obtaining the cumulative charge of each photon detection unit in the imaging detection array within a single frame, the photon intensity generated by the X-ray at each photon detection unit can be obtained based on the known correspondence between the cumulative charge and the photon intensity generated by the X-ray, thereby obtaining a two-dimensional intensity distribution map of the incident X-ray. It should be understood that the X-ray imaging detector can also be used to detect the cumulative charge on each photon detection unit within multiple frames, and the cumulative charge on each photon detection unit within multiple frames can be used to generate a two-dimensional intensity distribution map of the incident X-ray. The embodiments of the present disclosure do not limit the method for generating the two-dimensional intensity distribution map of the X-ray.

[0102] According to the X-ray imaging detection system of the embodiment of the present disclosure, a large dynamic range X-ray imaging detector can be used to achieve X-ray imaging detection with high signal-to-noise ratio, high readout frame rate, and large dynamic range, which is conducive to generating high-quality X-ray imaging results.

[0103] The schematic diagrams in the accompanying drawings show possible architectures, functions and operations of units, modules, devices and systems according to multiple embodiments of the present disclosure. In this regard, each box in the schematic diagram can represent a module, unit, device or part of a circuit, which contains one or more logic functions for implementing the specified function. In some alternative implementations, the functions marked in the boxes can also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the schematic diagram, and the combination of boxes in the schematic diagram, can be implemented using a dedicated hardware-based system that performs the specified function or action, or can be implemented using a combination of dedicated hardware and computer instructions.

[0104] While various embodiments of the present disclosure have been described above, the foregoing description is intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or technological improvements in the marketplace, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A photon detection unit, characterized in that: include: Photoelectric detection elements, charge-sensitive preamplifiers, comparators, charge pumps, counters, and voltage sampling circuits; Wherein, the photoelectric detection element is used to output a current signal corresponding to the energy of the incident photon to the input end of the charge-sensitive preamplifier; The charge-sensitive preamplifier is used to convert and amplify the current signal output by the photoelectric detection element into a voltage signal; The comparator is used to compare the voltage value of the voltage signal output by the charge-sensitive preamplifier with a reference voltage value, and output a control signal when the voltage value of the voltage signal output by the charge-sensitive preamplifier is higher than the reference voltage value; The charge pump is used to inject a specified amount of charge into the input terminal of the charge-sensitive preamplifier in response to the control signal output by the comparator to offset the current input by the photodetection element, thereby restoring the voltage value of the voltage signal output by the charge-sensitive preamplifier to a preset voltage value, wherein the preset voltage value is less than the reference voltage value; The counter is used to count the number of times the comparator outputs the control signal within a single frame time, and output a counting signal, wherein the counting signal represents the total number of times the comparator outputs the control signal within the single frame time; The voltage sampling circuit is used to sample the voltage value of the voltage signal output by the charge-sensitive preamplifier at the end of a single frame time, and output a sampling signal, wherein the sampling signal represents the voltage sampling value of the output end of the charge-sensitive preamplifier at the end of the single frame time; The counting signal and the sampling signal are used to determine the accumulated charge on the photoelectric detection element within a single frame time, and the accumulated charge is used to determine the intensity of incident photons.

2. The photon detection unit according to claim 1, characterized in that The photon detection unit further comprises: a first source follower connected to the output end of the counter, for isolating the counting signal output by the counter; The second source follower connected to the output end of the voltage sampling circuit is used to isolate the sampling signal output by the voltage sampling circuit.

3. The photon detection unit according to claim 1, characterized in that The photon detection unit further comprises: The reset switch circuit is used to reset the charge-sensitive preamplifier and the photodetection element at the beginning of a single frame time.

4. The photon detection unit according to any one of claims 1 to 3, characterized in that: The photodetection element includes a photodiode; and the voltage sampling circuit includes a correlated double sampling circuit.

5. An imaging detection array, characterized in that: An array comprising a plurality of photon detection units according to any one of claims 1 to 4.

6. An X-ray imaging detection module, characterized in that: include: X-ray scintillator, used to generate photons after interacting with incident X-rays; as well as, The imaging detection array of claim 5, wherein the imaging detection array is configured to detect photons generated by the X-ray scintillator and output analog detection signals; The analog detection signal includes a detection signal output by each photon detection unit in the imaging detection array, and the detection signal includes a counting signal and a sampling signal.

7. An X-ray imaging detector, characterized in that: include: The X-ray imaging detection module according to claim 6; as well as, The readout circuit module is used to process the analog detection signal output by the imaging detection array in the X-ray imaging detection module into a digital detection signal and output it to the outside of the chip.

8. The imaging detector according to claim 7, characterized in that The imaging detection array in the X-ray imaging detection module and the readout circuit module are integrated on the same chip.

9. An X-ray imaging detection system, characterized in that: include: The X-ray imaging detector according to claim 7 or 8; as well as, The host computer is used to generate an X-ray imaging result according to the digital detection signal output by the X-ray imaging detector, wherein the X-ray imaging result represents a two-dimensional intensity distribution diagram of the incident X-ray.

10. The system according to claim 9, characterized in that The digital detection signal represents the total number of times output by the counter in each photon detection unit and the voltage sampling value output by the voltage sampling circuit; wherein, generating the X-ray imaging result according to the digital detection signal output by the X-ray imaging detector includes: For the total number of times output by the counter in any photon detection unit and the voltage sampling value output by the voltage sampling circuit, the product of the total number of times and the specified charge amount is added to the charge amount corresponding to the voltage sampling value to obtain the cumulative charge amount of the photon detection unit within a single frame time; An X-ray imaging result is generated according to the accumulated charge amount of each photon detection unit in the imaging detection array in the X-ray imaging detector within a single frame time.

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