Photon energy spectrum detector based on temperature dynamic correction

Abstract

The invention discloses a photon energy spectrum detector based on dynamic temperature correction. The photon energy spectrum detector comprises a scintillation crystal module, a photoelectric conversion module, a charge-time conversion module, a temperature detection module and a signal processing module, the scintillation crystal module is used for receiving incident X-rays and converting the X-rays into scintillation light; the photoelectric conversion module is used for capturing the scintillation light generated by the scintillation crystal module and generating a plurality of charges so as to convert the scintillation light into an electric signal; the charge-time conversion module is used for converting the electric signal into a pulse width signal; the temperature detection module is used for detecting the real-time temperature in the photon energy spectrum detector; and the signal processing module is used for performing time digital conversion processing on the pulse width signal to obtain photon energy information, and correcting the photon energy information according to the detected real-time temperature to obtain corrected photon energy information. According to the photon energy spectrum detector, the technical problem that the existing X-ray detection device has limitation on photon energy spectrum detection and is difficult to meet the high-precision application requirement is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of X-ray detection, and in particular to a photon energy spectrum detector based on temperature dynamic correction. Background Art

[0002] In the field of X-ray detection technology, accurately acquiring X-ray photon energy spectrum information is crucial for numerous applications. In medical CT imaging, high-precision photon energy spectrum detection can significantly improve image contrast and resolution, helping doctors more accurately diagnose conditions and detect early, subtle lesions, providing critical evidence for clinical treatment. In bone density measurement, precise energy spectrum detection helps more accurately assess bone health, enabling early detection of bone diseases like osteoporosis and facilitating timely intervention. In security inspection equipment, when using X-rays for object inspection, high-precision photon energy spectrum detection devices can more accurately identify the composition and structure of different substances, improving the accuracy and efficiency of security inspections and effectively ensuring public safety. In X-ray spectral analysis, precise measurement of photon energy spectra enables in-depth analysis of the elemental composition and structural information of substances, playing a vital role in fields such as materials science and environmental monitoring. However, existing X-ray detection devices have limitations in the accuracy of photon energy spectrum detection, making it difficult to meet the growing demand for high-precision applications. Summary of the Invention

[0003] The main technical problem solved by the present invention is that the current X-ray detection device has limitations in the accuracy of photon energy spectrum detection and is difficult to meet the requirements of high-precision applications.

[0004] According to the first aspect, an embodiment provides a photon energy spectrum detector based on temperature dynamic correction, the photon energy spectrum detector comprising a scintillation crystal module, a photoelectric conversion module, a charge-time conversion module, a temperature detection module and a signal processing module;

[0005] The scintillation crystal module is used to receive incident X-rays and convert the X-rays into scintillation light;

[0006] The photoelectric conversion module is used to capture the scintillation light generated by the scintillation crystal module and generate a plurality of charges to convert the scintillation light into an electrical signal;

[0007] The charge-time conversion module is used to convert the electrical signal into a pulse width signal; wherein the pulse width signal contains photon energy information;

[0008] The temperature detection module is used to detect the real-time temperature inside the photon energy spectrum detector;

[0009] The signal processing module is used to perform time-to-digital conversion processing on the pulse width signal to obtain photon energy information, and to correct the photon energy information according to the detected real-time temperature to obtain corrected photon energy information.

[0010] In some embodiments, the signal processing module includes a temperature gain lookup table, wherein the temperature gain lookup table includes gain values ​​corresponding to each channel of the photon energy spectrum detector at different temperatures, and the photon energy information includes photon energy information of each channel of the photon energy spectrum detector; the signal processing module performs time-to-digital conversion processing on the pulse width signal to obtain photon energy information, and corrects the photon energy information according to the detected real-time temperature to obtain corrected photon energy information, including:

[0011] The signal processing module determines the current gain value corresponding to each channel of the photon energy spectrum detector according to the detected real-time temperature and the temperature gain lookup table;

[0012] The signal processing module performs gain correction on the photon energy information of each channel of the photon energy spectrum detector based on the current gain value corresponding to the channel to obtain corrected photon energy information.

[0013] In some embodiments, the temperature detection module includes a plurality of temperature sensors, wherein the plurality of temperature sensors are disposed directly below or on the back of the photoelectric conversion module.

[0014] In some embodiments, the charge-to-time conversion module includes a charge collector, a constant current source, and a threshold comparator;

[0015] The charge collector is used to collect multiple charges generated by the photoelectric conversion module;

[0016] The constant current source is used to discharge the multiple charges accumulated in the charge collector at a preset current rate;

[0017] The threshold comparator is used to receive a voltage signal generated during the discharge process of the constant current source, and generate a pulse width signal according to a result obtained by comparing the voltage signal with a preset voltage threshold.

[0018] In some embodiments, the charge collector is composed of a capacitor, and the constant current source includes an operational amplifier, a discharge resistor, and a diode;

[0019] The operational amplifier includes an inverting input terminal, a non-inverting input terminal, and an output terminal; the inverting input terminal of the operational amplifier is connected to the photoelectric conversion module, the non-inverting input terminal of the operational amplifier is connected to the reference voltage, and the output terminal of the operational amplifier is connected to the threshold comparator;

[0020] The discharge resistor includes a first end and a second end; the first end of the discharge resistor is connected to the inverting input end of the operational amplifier, and the second end of the discharge resistor is grounded;

[0021] The diode includes an anode and a cathode; the cathode of the diode is connected to the inverting input terminal of the operational amplifier, and the anode of the diode is connected to the output terminal of the operational amplifier;

[0022] The capacitor includes a first end and a second end. The first end of the capacitor is connected to the first end of the discharge resistor, and the second end of the capacitor is connected to the output end of the operational amplifier.

[0023] In some embodiments, the scintillation crystal module includes a LYSO crystal, the photoelectric conversion module includes a SiPM array, the signal processing module includes an FPGA, and the photon energy spectrum detector is encapsulated in an electromagnetically shielded metal box; wherein the LYSO crystal is encapsulated by aluminum foil, and a reflective layer is provided on the surface of the LYSO crystal, and the LYSO crystal is coupled to the SiPM array.

[0024] In some embodiments, the signal processing module performs time-to-digital conversion on the pulse width signal to obtain photon energy information, including:

[0025] The signal processing module performs sliding average processing on the pulse width signal to obtain a pulse width signal after sliding average processing;

[0026] The signal processing module performs time-to-digital conversion processing on the pulse width signal after the sliding average processing to obtain photon energy information.

[0027] In some embodiments, the photon energy spectrum detector also includes a data analysis module, which is used to receive the corrected photon energy information output by the signal processing module, and perform data analysis processing on the corrected photon energy information to obtain data analysis results; wherein, the data analysis processing includes photon counting, pixel uniformity correction processing, inter-pixel gain correction processing, noise suppression processing, pulse shaping processing and energy resolution processing.

[0028] In some embodiments, a counter is provided in the data analysis module, and the counter is used to count photons of the corrected photon energy information to obtain a photon counting result; wherein, the counter has N soft pulse width thresholds and N / 2 energy segments, and is used to count photons in each energy segment.

[0029] In some embodiments, the photon energy spectrum detector includes an analog ground, a digital ground, and a signal ground. The analog ground is the reference potential point of the analog circuit in the photon energy spectrum detector, the digital ground is the reference potential point of the digital circuit in the photon energy spectrum detector, and the signal ground is the reference potential point for signal transmission and processing in the photon energy spectrum detector; wherein the analog ground and the digital ground are isolated by magnetic beads to prevent the noise of the digital circuit from interfering with the analog circuit, and the signal ground is isolated from the earth by magnetic beads to reduce the noise interference caused by the earth to the signal ground.

[0030] According to the photon energy spectrum detector based on temperature dynamic correction of the above embodiment, since a scintillation crystal module and a photoelectric conversion module are designed in the photon energy spectrum detector, the efficiency of light collection can be improved through the coordinated work of the scintillation crystal module and the photoelectric conversion module. The charge-time conversion module can convert the electrical signal output by the photoelectric conversion module into a pulse width signal carrying photon energy information, so that the signal processing module can perform time-to-digital conversion processing on the pulse width signal and obtain continuous photon energy information. By digitally analyzing the electrical signal generated by the photoelectric conversion module, the accuracy of single photon energy value recognition is improved. At the same time, the real-time temperature inside the photon energy spectrum detector is detected by the temperature detection module, and the photon energy information is corrected according to the detected real-time temperature to obtain the corrected photon energy information, thereby avoiding the situation where the gain stability of the photon energy information is insufficient due to changes in the internal temperature of the photon energy spectrum detector, thereby significantly improving the single photon energy resolution and optimizing the anti-interference ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the structure of a photon energy spectrum detector based on temperature dynamic correction in an embodiment of the present application;

[0032] Figure 2 Schematic diagram of the structure of a charge-time conversion module according to an embodiment;

[0033] Figure 3 Schematic diagram of the structure of a charge-time conversion module according to an embodiment;

[0034] Figure 4 A timing diagram of a charge integration-constant current discharge process according to an embodiment;

[0035] Figure 5 A schematic structural diagram of a photon energy spectrum detector based on temperature dynamic correction according to an embodiment;

[0036] Figure 6 A reference diagram of photon energy spectrum counts when the soft pulse width threshold is 16 according to an embodiment;

[0037] Figure 7The figure is a schematic diagram of the mechanical structure of a photon energy spectrum detector based on temperature dynamic correction according to an embodiment. DETAILED DESCRIPTION

[0038] The present invention will be further described in detail below by means of specific embodiments in conjunction with the accompanying drawings. Similar elements in different embodiments are numbered with associated similar elements. In the following embodiments, many detailed descriptions are provided to enable the present application to be better understood. However, those skilled in the art will readily appreciate that some of the features may be omitted in different circumstances, or may be replaced by other elements, materials, or methods. In some cases, some operations related to the present application are not shown or described in the specification. This is to avoid the core portion of the present application being overwhelmed by excessive descriptions, and for those skilled in the art, it is not necessary to describe these related operations in detail. They will fully understand the related operations based on the description in the specification and the general technical knowledge in the art.

[0039] In addition, the features, operations, or characteristics described in the specification may be combined in any appropriate manner to form various embodiments. Furthermore, the steps or actions in the method description may be reordered or adjusted in a manner readily apparent to those skilled in the art. Therefore, the various sequences in the specification and drawings are provided solely for the purpose of clearly describing a particular embodiment and are not intended to be mandatory, unless otherwise specified.

[0040] The serial numbers assigned to components herein, such as "first," "second," etc., are used solely to distinguish the objects being described and do not convey any sequential or technical meaning. References to "connection" and "coupling" herein, unless otherwise specified, include both direct and indirect connections (couplings).

[0041] Current photon counting X-ray energy spectrum detectors mainly use the multi-voltage threshold comparison method (MVT), which divides the energy range through multiple comparators. However, it has the following defects: (1) Low energy resolution: It cannot identify the fine energy value of a single photon; (2) High circuit complexity: The discrete signal processing module results in a large size and poor anti-interference ability; (3) Sensitive to temperature drift: The temperature compensation mechanism is not integrated, resulting in insufficient gain stability.

[0042] In response to the above-mentioned defects, the present application proposes a photon energy spectrum detector with an integrated charge-time conversion module, a dynamic temperature compensation algorithm and a modular layout, which achieves a significant improvement in single-photon energy resolution and optimization of anti-interference capability. The embodiment of the present application provides a photon energy spectrum detector based on temperature dynamic correction, which includes a scintillation crystal module, a photoelectric conversion module, a charge-time conversion module, a temperature detection module and a signal processing module. The scintillation crystal module is used to receive incident X-rays and convert the X-rays into scintillation light; the photoelectric conversion module is used to capture the scintillation light generated by the scintillation crystal module and generate multiple charges to convert the scintillation light into an electrical signal; the charge-time conversion module is used to convert the electrical signal into a pulse width signal; wherein the pulse width signal contains photon energy information; the temperature detection module is used to detect the real-time temperature inside the photon energy spectrum detector; the signal processing module is used to perform time-to-digital conversion processing on the pulse width signal to obtain photon energy information, and correct the photon energy information according to the detected real-time temperature to obtain the corrected photon energy information.

[0043] The following describes the photon energy spectrum detector based on temperature dynamic correction provided by the embodiments of the present application in conjunction with the accompanying drawings. Figure 1 FIG. 1 shows a schematic diagram of the structure of a photon energy spectrum detector based on temperature dynamic correction provided by an embodiment of the present application. Figure 1 As shown, the photon energy spectrum detector includes a scintillation crystal module 10, a photoelectric conversion module 20, a charge-time conversion module 30, a temperature detection module 40 and a signal processing module 50, which are described in detail below.

[0044] The scintillation crystal module 10 is used to receive incident X-rays and convert the X-rays into scintillation light.

[0045] Specifically, the scintillation crystal module 10 includes inorganic scintillation crystals, organic scintillation crystals and composite scintillation crystals.

[0046] For example, the scintillation crystal module 10 may be a LYSO scintillation crystal. When incident X-rays strike the LYSO scintillation crystal, the LYSO scintillation crystal generates blue light primarily concentrated at 420 nanometers, thereby converting the X-rays into scintillation light. The intensity of the scintillation light is proportional to the energy of the X-rays.

[0047] In the embodiment of the present application, the scintillation crystal module 10 can efficiently convert the energy of incident X-rays into scintillation light, thereby improving the sensitivity of the photon energy spectrum detector.

[0048] The photoelectric conversion module 20 is used to capture the scintillation light generated by the scintillation crystal module 10 and generate a plurality of charges to convert the scintillation light into an electrical signal.

[0049] Specifically, the photoelectric conversion module 20 includes a silicon photomultiplier tube. The scintillation light generated by the scintillation crystal module 10 is captured by the silicon photomultiplier tube and generates a plurality of charges, thereby converting the scintillation light generated by the scintillation crystal module 10 into an electrical signal.

[0050] In the embodiment of the present application, the silicon photomultiplier tube in the photoelectric conversion module 20 has high sensitivity and can detect weak flickering light signals and convert them into corresponding electrical signals.

[0051] The charge-time conversion module 30 is used to convert the electrical signal into a pulse width signal.

[0052] Specifically, the original electrical signal typically contains complex characteristics such as amplitude and time, making it difficult to process directly. However, the conversion of the charge-to-time conversion module 30 into a pulse width signal simplifies the signal format. Furthermore, because the pulse width signal contains photon energy information, differences in the pulse width signal can more accurately reflect differences in photon energy.

[0053] In the embodiment of the present application, the electrical signal is converted into a pulse width signal by the charge-time conversion module 30, which can simplify the signal processing process and improve the energy resolution.

[0054] The temperature detection module 40 is used to detect the real-time temperature inside the photon energy spectrum detector.

[0055] Specifically, the temperature detection module 40 includes a plurality of temperature sensors, and detects the real-time temperature inside the photon energy spectrum detector in real time through the plurality of temperature sensors.

[0056] In the embodiments of this application, since the performance of the photon spectrum detector is affected by temperature, the detector's internal temperature is monitored in real time and its operating parameters are dynamically adjusted based on temperature changes, ensuring that it always maintains optimal operating conditions. Furthermore, by designing multiple temperature sensors, temperature changes within the detector can be comprehensively monitored, ensuring stable operation in various environments.

[0057] The signal processing module 50 is used to perform time-to-digital conversion processing on the pulse width signal to obtain photon energy information, and to correct the photon energy information according to the detected real-time temperature to obtain corrected photon energy information.

[0058] Specifically, the signal processing module 50 includes an FPGA. The FPGA performs time-to-digital conversion on the pulse width signal, which contains photon energy information, to obtain continuous photon energy information. Simultaneously, the photon energy information is corrected based on the detected real-time temperature to adjust the photon energy pulse width gain in real time, resulting in corrected photon energy information.

[0059] In the embodiment of the present application, considering that temperature changes may cause changes in the performance of the internal components of the photon energy spectrum detector and the measurement accuracy of the time-to-digital conversion process, the pulse width signal is subjected to time-to-digital conversion processing and then corrected in combination with the real-time temperature to reduce the impact of the error of the time-to-digital conversion process on the photon energy measurement.

[0060] In some embodiments, the signal processing module 50 includes an FPGA. The pulse width signal contains photon energy information. The FPGA can be used to perform time-to-digital conversion on the pulse width signal to obtain continuous photon energy information.

[0061] According to the photon energy spectrum detector based on temperature dynamic correction in the above embodiment, since the scintillation crystal module 10 and the photoelectric conversion module 20 are designed in the photon energy spectrum detector, the efficiency of light collection can be improved through the coordinated operation of the scintillation crystal module 10 and the photoelectric conversion module 20. The charge-time conversion module 30 can convert the electrical signal output by the photoelectric conversion module 20 into a pulse width signal carrying photon energy information, so that the signal processing module 50 can perform time-to-digital conversion processing on the pulse width signal and obtain continuous photon energy information. By digitally analyzing the electrical signal generated by the photoelectric conversion module 20, the accuracy of single photon energy value recognition is improved. At the same time, the temperature detection module 40 detects the real-time temperature inside the photon energy spectrum detector and corrects the photon energy information based on the detected real-time temperature to obtain the corrected photon energy information. This avoids the situation where the gain stability of the photon energy information is insufficient due to changes in the internal temperature of the photon energy spectrum detector, thereby significantly improving the single photon energy resolution and optimizing the anti-interference capability.

[0062] In some embodiments, the signal processing module 50 includes a temperature gain lookup table, wherein the temperature gain lookup table includes gain values ​​corresponding to each channel of the photon energy spectrum detector at different temperatures, and the photon energy information includes photon energy information of each channel of the photon energy spectrum detector. The signal processing module 50 performs time-to-digital conversion processing on the pulse width signal to obtain photon energy information, and corrects the photon energy information based on the detected real-time temperature to obtain corrected photon energy information, including:

[0063] The signal processing module 50 determines the current gain value corresponding to each channel of the photon energy spectrum detector according to the detected real-time temperature and the temperature gain lookup table;

[0064] The signal processing module 50 performs gain correction on the photon energy information of each channel based on the current gain value corresponding to the channel of the photon energy spectrum detector to obtain corrected photon energy information.

[0065] Specifically, a plurality of temperature sensors are installed in the photon energy spectrum detector to monitor the real-time temperature of the environment in which each channel of the photon energy spectrum detector is located in real time. By pre-testing the temperature-gain characteristics of each channel of the photon energy spectrum detector, the gain value of each channel is measured at different temperature points, and a temperature gain lookup table is generated based on the temperature points and gain values. The temperature gain lookup table takes temperature as input and the corresponding gain value as output, and is stored in the photon energy spectrum detector in a tabular form. The detected real-time temperature is matched with the temperature gain lookup table, and the temperature point closest to the real-time temperature is quickly located in the temperature gain lookup table, and the gain value corresponding to the temperature point is read as the gain value of the current channel. The photon energy information of each channel is gain-corrected according to the current gain value corresponding to the channel. The correction formula can be: corrected photon energy information = photon energy information of the channel / gain value of the current channel.

[0066] In the embodiments of the present application, temperature changes can cause the gain of each channel of the photon energy spectrum detector to change, thereby affecting the accuracy of the measured photon energy information. By performing gain correction based on real-time temperature and a temperature gain lookup table, the effect of temperature on gain can be effectively eliminated, making the measured photon energy information more accurate, thereby improving the accuracy of energy spectrum measurement.

[0067] In some embodiments, the temperature detection module 40 includes a plurality of temperature sensors, wherein the plurality of temperature sensors are disposed directly below or on the back of the photoelectric conversion module 20 .

[0068] Specifically, multiple temperature sensors are positioned directly below or on the back of the photoelectric conversion module 20. Positioning them directly below allows for more direct detection of the heat generated by the photoelectric conversion module 20 during operation and the effect of the ambient temperature on it, while positioning them on the back helps detect the overall heat dissipation of the photon energy spectrum detector and the indirect effect of the external temperature on the photoelectric conversion module 20. The specific number of temperature sensors can be determined based on the size and shape of the photoelectric conversion module 20. Generally, four temperature sensors are deployed to ensure comprehensive and accurate acquisition of temperature information.

[0069] In the embodiment of the present application, multiple temperature sensors are set at key positions of the photoelectric conversion module 20, which can more accurately monitor the temperature changes of the photon energy spectrum detector, thereby more effectively performing temperature compensation and reducing the impact of temperature on the measurement results.

[0070] In some embodiments, please refer to Figure 2The charge-time conversion module 30 includes a charge collector 301, a constant current source 302, and a threshold comparator 303. The charge collector 301 is used to collect multiple charges generated by the photoelectric conversion module 20. The constant current source 302 is used to discharge the multiple charges accumulated in the charge collector 301 at a preset current rate. The threshold comparator 303 is used to receive the voltage signal generated by the constant current source 302 during the discharge process and generate a pulse width signal based on the result of comparing the voltage signal with a preset voltage threshold.

[0071] Specifically, charge collector 301 is typically a capacitor that collects charge generated by radiation particles during the operation of photomultiplier tube 20. The preset current rate can be a constant current rate. When the charge in charge collector 301 accumulates to a preset amount, constant current source 302 begins to discharge charge collector 301 at a constant current rate. Threshold comparator 303 can be an FPGA.

[0072] In some embodiments, please refer to Figure 3 The charge collector 301 is composed of a capacitor, and the constant current source 302 includes an operational amplifier 302a, a discharge resistor 302b, and a diode 302c. The operational amplifier 302a includes an inverting input, a non-inverting input, and an output. The inverting input of the operational amplifier 302a is connected to the photoelectric conversion module 20, the non-inverting input of the operational amplifier 302a is connected to the reference voltage, and the output of the operational amplifier 302a is connected to the threshold comparator 303. The discharge resistor 302b includes a first end and a second end. The first end of the discharge resistor 302b is connected to the inverting input of the operational amplifier 302a, and the second end of the discharge resistor 302b is grounded. The diode 302c includes an anode and a cathode. The cathode of the diode 302c is connected to the inverting input of the operational amplifier 302a, and the anode of the diode 302c is connected to the output of the operational amplifier 302a. The capacitor includes a first end and a second end. The first end of the capacitor is connected to the first end of the discharge resistor 302b, and the second end of the capacitor is connected to the output of the operational amplifier 302a.

[0073] Specifically, when there is no input signal at the inverting input of the operational amplifier 302a, the diode 302c is turned on, and negative feedback of the operational amplifier is formed. At this time, the voltage at the inverting input of the operational amplifier 302a is the same as the voltage at the non-inverting input, that is, the voltage at the inverting input of the operational amplifier 302a is the reference voltage Vp. Therefore, the corresponding discharge current can be calculated based on the reference voltage Vp and the discharge resistor 302b. When there is a positive input current at the inverting input of the operational amplifier 302a and the positive input current is greater than the discharge current, a constant portion of the positive input current is discharged through the discharge resistor 302b, and the remaining current in the positive input current is transferred to the capacitor to charge the capacitor. When the capacitor accumulates a preset amount of charge, the capacitor is discharged through the discharge resistor 302b.

[0074] Specifically, when diode 302c is turned on, the voltage at the cathode of diode 302c is the reference voltage Vp. Due to the negative feedback of the operational amplifier, the voltage at the anode of diode 302c is Vp+Vd, where Vd is the forward conduction voltage of diode 302c. During the charging process of the capacitor, the voltage at the first end of the capacitor is the reference voltage Vp, and the voltage at the second end of the capacitor changes to Vp-V1 as the capacitor charges, where V1 is the voltage generated by the residual current transferred to the capacitor to charge. Since the voltage at the second end of the capacitor changes to Vp-V1, the voltage at the anode of diode 302c changes from Vp+Vd to Vp-V1. At this time, the voltage difference between the anode and cathode of diode 302c is less than the minimum forward conduction voltage, causing diode 302c to be cut off. Therefore, when the capacitor is charging, when the charge accumulates to a preset charge amount, the capacitor charging ends and begins to discharge to the discharge resistor 302b with a constant current.

[0075] Specifically, the anode of diode 302c is connected to the output of operational amplifier 302a. Therefore, during the capacitor charging process, the voltage at the anode of diode 302c changes from Vp+Vd to Vp-V1 as the capacitor charges, causing the voltage output by operational amplifier 302a to decrease. Similarly, during the constant current discharge of the capacitor through discharge resistor 302b, the voltage at the anode of diode 302c gradually increases until the voltage at the anode of diode 302c returns to Vp+Vd. At this point, diode 302c reopens, and the voltage output by operational amplifier 302a also rises and returns to Vp+Vd. Since the signal from operational amplifier 302a is sent to threshold comparator 303, the decreasing or increasing voltage output by operational amplifier 302a is compared with the threshold value in threshold comparator 303 to generate a pulse width signal.

[0076] In the embodiment of the present application, since the width of the output signal of the charge-time conversion circuit 30 is proportional to the input charge, it can be easily converted into a digital value in the programmable logic device FPGA, thereby realizing subsequent photon energy measurement and other data analysis and processing.

[0077] In some embodiments, a low-noise operational amplifier can be connected in parallel with a capacitor, and the low-noise operational amplifier can be combined with a Schottky diode and a resistor, wherein the Schottky diode and the resistor form a stable constant current source 302 to construct the charge-time conversion module 30 as a whole.

[0078] In some embodiments, the scintillation crystal module 10 includes a LYSO crystal, the photoelectric conversion module 20 includes a SiPM array, the signal processing module 50 includes an FPGA, and the photon energy spectrum detector is encapsulated in an electromagnetically shielded metal box. The LYSO crystal is encapsulated in aluminum foil and has a reflective layer on its surface. The LYSO crystal is coupled to the SiPM array.

[0079] Specifically, the scintillation crystal module 10 can be a LYSO crystal with a reflective layer on its surface to improve light collection efficiency. The photoelectric conversion module 20 can be a SiPM array, coupled to the LYSO crystal using optical glue, which is directly bonded to the light-emitting surface of the crystal. The matching error between the two is less than 0.1 mm.

[0080] In an embodiment of the present application, the photon energy spectrum detector is encapsulated as a whole in an electromagnetic shielding metal box, which is suitable for the fields of medical imaging and industrial non-destructive testing, and the LYSO crystal is coupled with the SiPM array to improve the efficiency of light collection.

[0081] In some embodiments, the signal processing module 50 performs time-to-digital conversion on the pulse width signal to obtain photon energy information, including:

[0082] The signal processing module 50 performs sliding average processing on the pulse width signal to obtain a pulse width signal after sliding average processing;

[0083] The signal processing module 50 performs time-to-digital conversion on the pulse width signal after the sliding average processing to obtain photon energy information.

[0084] Specifically, an adaptive filtering algorithm is embedded in the signal processing module 50, and the pulse width signal is subjected to sliding average processing by the adaptive filtering algorithm to suppress random noise, and the pulse width signal after the sliding average processing is subjected to time-to-digital conversion processing to obtain more accurate photon energy information.

[0085] In some embodiments, signal processing module 50 may be an FPGA. By integrating a time-to-digital converter and an adaptive filtering algorithm, signal processing can be improved. Signal processing module 50 may use an LVDS pin as a threshold comparator 303 to convert the analog pulse width signal output by operational amplifier 302a into a digital pulse width signal. The FPGA communicates with a host computer via an Ethernet interface and transmits energy data and photon count data.

[0086] For some examples, please refer to Figure 4 The charge integration-constant current discharge sequence in a photon energy spectrum detector can be described as follows: photon incidence → LYSO crystal luminescence → SiPM charge pulse output → integration capacitor charging to peak value → constant current source linear discharge → pulse width signal generation. The pulse width signal is positively correlated with photon energy and can be calculated using the formula T = Q / I, where Q is the charge and I is the constant current source current, for example, 1 mA. Signal processing module 50 includes an FPGA, which performs time-to-digital conversion on the pulse width signal.

[0087] In some embodiments, please refer to Figure 5 The photon energy spectrum detector further includes a data analysis module 60, which is configured to receive the corrected photon energy information output by the signal processing module 50 and perform data analysis on the corrected photon energy information to obtain data analysis results. The data analysis process includes photon counting, pixel uniformity correction, inter-pixel gain correction, noise suppression, pulse shaping, and energy resolution.

[0088] Specifically, the data analysis module 60 includes an FPGA. The data analysis module 60 and the signal processing module 50 can be the same FPGA, that is, the FPGA can convert the pulse width signal into photon energy information and perform further data analysis and processing on the photon energy information.

[0089] In the embodiment of the present application, the performance of the photon energy spectrum detector is improved by further data analysis and processing on the photon energy information.

[0090] In some embodiments, the data analysis module 60 is provided with a counter for counting photons of the corrected photon energy information to obtain a photon counting result. The counter has N soft pulse width thresholds and N / 2 energy segments, and is used to count photons within each energy segment.

[0091] Specifically, please refer to Figure 6 When N is 16, it can be divided into 8 energy segments, and the counter can count the photons in the 8 energy segments.

[0092] In an embodiment of the present application, the counter has N soft pulse width thresholds, and the counter can combine N / 2 energy segments to count photons in each energy segment, thereby realizing the multifunctional counting function of the photon energy spectrum detector.

[0093] In some embodiments, the photon counting X-ray detector of the multi-voltage threshold digitizer constructed by SiPM and FPGA only divides the collected signal into several energy segments. Since the collected signal does not trigger the event of the threshold comparator, it will be lost. Therefore, the data processing methods that can be done are limited. The photon energy spectrum detector in the embodiment of the present application can convert the captured photon energy into a pulse width signal, and use a counter inside the FPGA to perform time-to-digital conversion on the pulse width signal to obtain continuous photon energy information. Compared with only dividing the signal into several energy segments, the captured photon energy can be distinguished more finely. At the same time, since continuous photon energy information is obtained, more diverse data processing can be performed, such as pixel uniformity correction, inter-pixel gain correction, temperature correction, noise suppression, pulse shaping and energy resolution, etc., to improve the performance of the photon energy spectrum detector.

[0094] In some embodiments, pixel uniformity variations are caused by several key factors, including variations in the coupling between the scintillator crystal and the SiPM, variations between scintillator crystal pixels, variations in SiPM gain between pixels, and variations in analog circuitry between pixels. The accumulation of these factors can lead to gain variations between pixels. However, in the embodiments of the present application, complete energy information can be obtained through counting. Therefore, pixel uniformity correction can be achieved through continuous photon energy information and data processing in the FPGA.

[0095] In some embodiments, a photon energy spectrum detector includes an analog ground, a digital ground, and a signal ground. The analog ground serves as the reference potential for the analog circuits in the photon energy spectrum detector, the digital ground serves as the reference potential for the digital circuits in the photon energy spectrum detector, and the signal ground serves as the reference potential for signal transmission and processing in the photon energy spectrum detector. The analog ground and the digital ground are isolated by magnetic beads to prevent noise from the digital circuits from interfering with the analog circuits. The signal ground is isolated from the earth ground by magnetic beads to reduce noise interference from the earth ground on the signal ground.

[0096] In the embodiments of this application, magnetic beads are used to isolate the analog and digital grounds, effectively preventing noise from digital circuits from entering the analog circuits, thereby improving the quality of analog signals and ensuring the accuracy of measurement results. Using magnetic beads to isolate the signal ground from the earth reduces coupling of earth noise, making the signal ground more stable and improving signal quality.

[0097] In some embodiments, please refer to Figure 7The photon energy spectrum detector is housed in an aluminum alloy electromagnetic shielding box with heat dissipation fins designed near the FPGA. This design allows for passive heat dissipation near the FPGA, improving heat dissipation efficiency.

[0098] In some embodiments, the combination of scintillator crystal and photomultiplier tube can be replaced by a cadmium zinc telluride semiconductor detector, but its charge integration parameters need to be adjusted. SiPM can be replaced by a photomultiplier tube, but a high-voltage bias circuit needs to be added. FPGA can be replaced by a dedicated ASIC chip. This replacement sacrifices the programmability of FPGA to reduce costs.

[0099] In some embodiments, the present application has the following advantages: (1) Performance improvement: the energy resolution is increased from 4 levels of the conventional MVT to 512 levels; (2) Anti-interference design: metal shell shielding, and signal noise is reduced by isolating the signal ground from the earth magnetic beads; (3) FPGA embedded temperature gain curve, dynamically adjusting the gain of each channel according to the internal temperature of the photon energy spectrum detection; (4) Miniaturization: module integration reduces the size of the photon energy spectrum detector. In summary, the present application realizes the construction of a high-density, small-size and low-power X-ray photon energy spectrum detector by optimizing the charge-time conversion circuit structure and module integration design. The LYSO crystal is directly coupled with the SiPM to improve the light collection efficiency, and the FPGA is embedded with an adaptive filtering algorithm and a soft threshold dynamic adjustment function to support accurate division of multiple energy segments. The device of the photon energy spectrum detector is encapsulated in an electromagnetically shielded metal box and is suitable for medical imaging and industrial non-destructive testing.

[0100] Those skilled in the art will appreciate that all or part of the functions of the various methods in the above embodiments can be implemented by hardware or by computer program. When all or part of the functions in the above embodiments are implemented by computer program, the program can be stored in a computer-readable storage medium, and the storage medium can include: read-only memory, random access memory, disk, optical disk, hard disk, etc., and the program is executed by a computer to implement the above functions. For example, the program is stored in the memory of the device, and when the program in the memory is executed by the processor, all or part of the above functions can be implemented. In addition, when all or part of the functions in the above embodiments are implemented by computer program, the program can also be stored in a storage medium such as a server, another computer, disk, optical disk, flash disk or mobile hard disk, and saved in the memory of the local device by downloading or copying, or the system of the local device is updated. When the program in the memory is executed by the processor, all or part of the functions in the above embodiments can be implemented.

[0101] The above examples are used to illustrate the present invention, which are only used to help understand the present invention and are not intended to limit the present invention. Those skilled in the art can make several simple deductions, modifications or substitutions based on the concept of the present invention.

Claims

1. A photon energy spectrum detector based on temperature dynamic correction, characterized in that: The photon energy spectrum detector includes a scintillation crystal module, a photoelectric conversion module, a charge-time conversion module, a temperature detection module and a signal processing module; The scintillation crystal module is used to receive incident X-rays and convert the X-rays into scintillation light; The photoelectric conversion module is used to capture the scintillation light generated by the scintillation crystal module and generate a plurality of charges to convert the scintillation light into an electrical signal; The charge-time conversion module is used to convert the electrical signal into a pulse width signal; wherein the pulse width signal contains photon energy information; The temperature detection module is used to detect the real-time temperature inside the photon energy spectrum detector; The signal processing module is used to perform time-to-digital conversion processing on the pulse width signal to obtain photon energy information, and to correct the photon energy information according to the detected real-time temperature to obtain corrected photon energy information.

2. The photon energy spectrum detector according to claim 1, wherein: The signal processing module includes a temperature gain lookup table, wherein the temperature gain lookup table includes gain values ​​corresponding to each channel of the photon energy spectrum detector at different temperatures, and the photon energy information includes photon energy information of each channel of the photon energy spectrum detector; the signal processing module performs time-to-digital conversion processing on the pulse width signal to obtain photon energy information, and corrects the photon energy information according to the detected real-time temperature to obtain corrected photon energy information, including: The signal processing module determines the current gain value corresponding to each channel of the photon energy spectrum detector according to the detected real-time temperature and the temperature gain lookup table; The signal processing module performs gain correction on the photon energy information of each channel of the photon energy spectrum detector based on the current gain value corresponding to the channel to obtain corrected photon energy information.

3. The photon energy spectrum detector according to claim 1, wherein: The temperature detection module includes a plurality of temperature sensors, wherein the plurality of temperature sensors are arranged directly below or on the back of the photoelectric conversion module.

4. The photon energy spectrum detector according to claim 1, wherein: The charge-time conversion module includes a charge collector, a constant current source and a threshold comparator; The charge collector is used to collect multiple charges generated by the photoelectric conversion module; The constant current source is used to discharge the multiple charges accumulated in the charge collector at a preset current rate; The threshold comparator is used to receive a voltage signal generated during the discharge process of the constant current source, and generate a pulse width signal according to a result obtained by comparing the voltage signal with a preset voltage threshold.

5. The photon energy spectrum detector according to claim 4, characterized in that: The charge collector is composed of a capacitor, and the constant current source includes an operational amplifier, a discharge resistor and a diode; The operational amplifier includes an inverting input terminal, a non-inverting input terminal, and an output terminal; the inverting input terminal of the operational amplifier is connected to the photoelectric conversion module, the non-inverting input terminal of the operational amplifier is connected to the reference voltage, and the output terminal of the operational amplifier is connected to the threshold comparator; The discharge resistor includes a first end and a second end; the first end of the discharge resistor is connected to the inverting input end of the operational amplifier, and the second end of the discharge resistor is grounded; The diode includes an anode and a cathode; the cathode of the diode is connected to the inverting input terminal of the operational amplifier, and the anode of the diode is connected to the output terminal of the operational amplifier; The capacitor includes a first end and a second end. The first end of the capacitor is connected to the first end of the discharge resistor, and the second end of the capacitor is connected to the output end of the operational amplifier.

6. The photon energy spectrum detector according to claim 1, wherein: The scintillation crystal module includes a LYSO crystal, the photoelectric conversion module includes a SiPM array, the signal processing module includes an FPGA, and the photon energy spectrum detector is encapsulated in an electromagnetic shielding metal box; wherein the LYSO crystal is encapsulated by aluminum foil, and a reflective layer is provided on the surface of the LYSO crystal, and the LYSO crystal is coupled to the SiPM array.

7. The photon energy spectrum detector according to claim 1, wherein: The signal processing module performs time-to-digital conversion processing on the pulse width signal to obtain photon energy information, including: The signal processing module performs sliding average processing on the pulse width signal to obtain a pulse width signal after sliding average processing; The signal processing module performs time-to-digital conversion processing on the pulse width signal after the sliding average processing to obtain photon energy information.

8. The photon energy spectrum detector according to claim 1, wherein: The photon energy spectrum detector also includes a data analysis module, which is used to receive the corrected photon energy information output by the signal processing module and perform data analysis processing on the corrected photon energy information to obtain data analysis results; wherein, the data analysis processing includes photon counting, pixel uniformity correction processing, inter-pixel gain correction processing, noise suppression processing, pulse shaping processing and energy resolution processing.

9. The photon energy spectrum detector according to claim 8, characterized in that: The data analysis module is provided with a counter, which is used to count photons of the corrected photon energy information to obtain a photon counting result; wherein, the counter has N soft pulse width thresholds and N / 2 energy segments, and is used to count photons in each energy segment.

10. The photon energy spectrum detector according to claim 1, wherein: The photon energy spectrum detector includes an analog ground, a digital ground, and a signal ground. The analog ground is the reference potential point of the analog circuit in the photon energy spectrum detector, the digital ground is the reference potential point of the digital circuit in the photon energy spectrum detector, and the signal ground is the reference potential point for signal transmission and processing in the photon energy spectrum detector. The analog ground and the digital ground are isolated by magnetic beads to prevent the noise of the digital circuit from interfering with the analog circuit, and the signal ground is isolated from the earth by magnetic beads to reduce the noise interference caused by the earth to the signal ground.

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