Gamma ray imaging device and method based on perovskite semiconductor detector

Abstract

The invention belongs to the technical field of imaging, and relates to a gamma ray imaging device and method based on a perovskite semiconductor detector. Comprising a collimator array, a first detector array, a multi-channel front-end reading module, a data acquisition and processing module and an upper computer, the collimator array collimates gamma rays emitted by an object to be detected; the first detector array detects gamma rays emitted from different positions of an object to be detected by using a plurality of perovskite semiconductor detectors, and outputs a plurality of multi-channel sensing signals; the multi-channel front-end reading module extracts a first signal and a second signal from each multi-channel sensing signal; the data acquisition and processing module performs analog-to-digital conversion and data correction on the plurality of first signals and the plurality of second signals to obtain a plurality of corrected first digital signals and a plurality of second digital signals; and the upper computer performs image reconstruction based on each corrected first digital signal and each second digital signal to obtain a distribution image of the radioactive elements in the to-be-detected object.

Description

Technical Field

[0001] The present invention relates to the field of imaging technology, and in particular to a gamma-ray imaging device and method based on a perovskite semiconductor detector. Background Art

[0002] Nuclear medicine imaging based on the principle of radioisotope tracing is an important technical means in modern medical diagnosis, and plays an important role in the early diagnosis of major diseases, pathological research, drug development and other fields. It uses a gamma-ray "camera" to detect radioisotope tracers (such as 99m Tc, 131 I. 177 Gamma photons generated by the decay of radioactive nuclides (Lu) are converted into imaging data through signal conversion. Its unique imaging feature is that it transmits information about tissue functional status through the decay of radionuclides, thereby providing diagnostic information. Single-Photon Emission Computed Tomography (SPECT) is the most popular nuclear medicine imaging device, with extensive applications in life science research fields such as disease diagnosis, staging, prognosis, efficacy evaluation, treatment planning, and new drug development.

[0003] The core of the SPECT device is the gamma-ray imaging system, which mainly consists of two key components: a gamma-ray detector and a collimator. The gamma-ray detector is responsible for receiving multiple gamma photons emitted by the object being tested at different time points, and converting information such as the time, energy and position of each photon on the detector into an electrical signal, which is then digitally input into a computer for processing. The collimator is located between the object being tested and the detector. Its function is to selectively allow gamma photons from a specific direction to enter the detector, thereby providing incident direction information for subsequent image reconstruction. Over a certain period of time, each pixel unit on the detector accumulates the number of gamma photons received one by one, and inputs this data into the image reconstruction module in the computer. Through the image reconstruction algorithm, an image of the spatial distribution of the radioactive isotope in the body of the object being tested is finally generated.

[0004] Current detectors used in nuclear medicine imaging rely on two gamma-ray detection mechanisms: an indirect photoconversion mechanism based on a scintillator coupled to a photomultiplier tube (PMT), and a direct gamma-ray detection mechanism based on semiconductors. In the former, high-energy gamma-ray photons are first converted into optical photons by the scintillator and then into electrical signals by the PMT for signal acquisition and image construction. Semiconductor detectors, on the other hand, directly convert incident photons into electrical signals by generating electron-hole pairs. NaI (Tl) is currently the most commonly used scintillator in SPECT, but its inherent defects, such as poor high-energy radiation blocking capability, limited light yield (41,000 photons / MeV), nonlinear energy response, and crystalline deliquescent properties, remain the main limitations on conventional SPECT imaging performance. These defects result in low energy and spatial resolution, and are widely criticized for their poor detection sensitivity, severely hampering its diagnostic capabilities. In contrast, the output signal of semiconductor detectors is large and completely proportional to the energy of the incident gamma-ray photons, exhibiting excellent energy resolution. At the same time, compared with the isotropic light scattering in scintillators, the spatial diffusion of carriers in semiconductors is small. Combined with its smaller electrode size, the pixelated signal readout method of semiconductor detectors can achieve higher spatial resolution. In addition, more compact semiconductor detector modules also make more innovative imaging system designs possible.

[0005] Cadmium zinc telluride (Cd1−xZnxTe, CdZnTe) is currently the only room-temperature semiconductor used for imaging. SPECT based on pixel-type CdZnTe detectors demonstrates excellent image quality, with a 141 keV gamma-ray energy resolution of 6% and an intrinsic spatial resolution of 2.8 mm, while also offering high imaging efficiency. However, the lattice constant of CdZnTe is sensitive to temperature changes, and the difference in atomic radii between Cd and Zn leads to uneven temperature gradients and atomic diffusion rates in different regions during crystal cooling, resulting in subcrystallization, which disrupts the long-range order of the crystal and creates localized charge traps. Furthermore, because Te has a much higher vapor pressure than Cd, improper atmosphere control during crystal growth can lead to excessive Te precipitation and inclusions within the crystal. These subcrystallizations and inclusions directly impact the performance of the resulting detector. Using defective detectors can result in poor imaging quality, while producing high-performance detectors can lead to high production costs for CdZnTe detectors.

[0006] In summary, the existing gamma-ray imaging devices based on CdZnTe semiconductor detectors have the problem of not being able to strike a balance between imaging quality and cost. Summary of the Invention

[0007] Therefore, the technical problem to be solved by the present invention is to overcome the problem in the prior art that the gamma-ray imaging device based on the cadmium zinc telluride semiconductor detector cannot take into account both imaging quality and cost.

[0008] To solve the above technical problems, the present invention provides a gamma-ray imaging device based on a perovskite semiconductor detector, comprising: A collimator array, the geometric center of which is aligned with the center of the object to be detected, and is used to collimate gamma rays emitted from different positions of the object to be detected using each collimator in the collimator array; A first detector array includes a plurality of perovskite semiconductor detectors, wherein a plurality of pixelated electrodes of each perovskite semiconductor detector are aligned with a plurality of collimators in a collimator array; the first detector array is configured to detect gamma rays emitted from different positions of an object to be detected using the plurality of perovskite semiconductor detectors and output a plurality of multi-channel sensing signals; a multi-channel front-end readout module connected to the first detector array and configured to extract, from the plurality of multi-channel sensing signals, a plurality of first signals containing incident energy information and a plurality of second signals related to incident event time information using a plurality of channel signal readout circuits; a data acquisition and processing module connected to the multi-channel front-end readout module, configured to perform analog-to-digital conversion on the plurality of first signals and the plurality of second signals to obtain a plurality of first digital signals and a plurality of second digital signals; and to correct the plurality of first digital signals to obtain a plurality of corrected first digital signals; The host computer is in communication with the data acquisition and processing module and is used to perform image reconstruction based on each corrected first digital signal and each second digital signal to obtain a distribution image of the radioactive element in the object to be detected.

[0009] Preferably, each signal readout circuit comprises: A charge-sensitive preamplifier is used to detect and pre-amplify the multi-channel sensing signal to obtain the target multi-channel sensing signal; A first signal extraction circuit is connected to the charge-sensitive preamplifier and includes a slow shaper, a baseline restoration circuit, a peak detection and holding circuit, and a source follower connected in series, and is used to filter, restore the baseline, detect and hold the amplitude, and buffer the target multi-channel sensing signal, and output a first signal containing incident energy information; The second signal extraction circuit is connected to the charge-sensitive preamplifier and includes: A fast shaper, connected to the charge-sensitive preamplifier, is used to perform fast waveform shaping on the target multi-channel sensing signal; a digital-to-analog converter for generating a threshold voltage signal; a discriminator connected to the fast shaper and the digital-to-analog converter, and configured to compare the target multi-channel sensing signal output by the fast shaper with the threshold voltage signal, thereby discriminating and outputting an over-threshold signal in the target multi-channel sensing signal; The monostable circuit is connected to the discriminator and is used to generate a stable pulse signal with the starting time of the threshold-crossing signal as the starting point and the starting time of the output signal of the peak detection and holding circuit as the end point when the discriminator outputs the threshold-crossing signal, and output a second signal related to the time information of the incident event.

[0010] Preferably, the perovskite semiconductor of the perovskite semiconductor detector is a three-dimensional perovskite, a two-dimensional perovskite, a zero-dimensional perovskite or an antiperovskite; Wherein, the three-dimensional perovskite is A1B1X13, A1 is one or more of Na, K, Rb, Cs, Cu, T1, H3O; B1 is one or more of Pb, Si, Ge, Sn, Mg, Ca, Sr, Ba, Zn, Cd, Hg; X1 is one or more of F, Cl, Br, I, BF4, HCOO, OH, CN, SCN, NCS, SH, NO3, H2POO; The two-dimensional perovskite is T1PbI3 or A23B22X29, where A2 is one or both of Cs and Rb; B2 is one or both of Sb and Bi; and X2 is one or more of F, Cl, Br, and I. Zero-dimensional perovskites are Cs3Bi2I9, Cs2TeI6, Cs2TeBr6 or Cs2TeCl6; Antiperovskite is Hg3Se2Br2 or T1Sn2I5.

[0011] Preferably, the perovskite semiconductor detector is a planar array pixel detector, the pixel shape is square, circular or hexagonal, and the pixel size is 0.01mm~100mm; or, the perovskite semiconductor detector is a strip-shaped one-dimensional array detector, and the strip size is 0.01mm~100mm; The thickness of the perovskite semiconductor detector is 0.5mm~50mm.

[0012] Preferably, it also includes: The second detector array is arranged on the side of the first detector array away from the collimator array, and includes multiple perovskite semiconductor detectors. It is used to detect gamma rays emitted from different positions of the object to be detected using multiple perovskite semiconductor detectors, and output multiple multi-channel sensing signals so that the multi-channel front-end readout module, the data acquisition and processing module and the host computer can obtain a distribution image of the radioactive elements in the object to be detected based on the multi-channel sensing signals output by the first detector array and the second detector array.

[0013] Preferably, the collimator is a pinhole collimator, a parallel hole collimator, a diverging collimator or a converging collimator.

[0014] Preferably, the host computer is connected to the collimator array and the first detector array, and is used to control the collimator array and the first detector array to rotate around the object to be detected, so as to collect gamma rays emitted from multiple projection angles of the object to be detected.

[0015] Preferably, the data acquisition and processing module includes: an analog-to-digital converter, connected to the multi-channel front-end readout module, for converting the plurality of first signals and the plurality of second signals into a plurality of first digital signals and a plurality of second digital signals; The FPGA is communicatively connected to the analog-to-digital converter and the host computer, and is used to receive multiple first digital signals and multiple second digital signals after analog-to-digital conversion, and based on the control signal of the host computer, use an energy attenuation correction algorithm to correct each first digital signal, and use a depth correction algorithm based on the second digital signal and the internal weight potential distribution model of the perovskite semiconductor detector to further correct each first digital signal to compensate for the signal amplitude loss caused by the weight potential loss of the internal structure of the perovskite semiconductor detector; and transmit the multiple corrected first digital signals and multiple second digital signals to the host computer.

[0016] Preferably, the host computer specifically includes: The image reconstruction module is used to receive each corrected first digital signal and each second digital signal, and use a filtered back projection algorithm and an iterative reconstruction algorithm to perform three-dimensional image reconstruction on the received multiple signals to obtain the distribution of radioactive elements in the object to be detected.

[0017] The present invention also provides a gamma-ray imaging method based on a perovskite semiconductor detector, which is implemented using the above-mentioned gamma-ray imaging device based on a perovskite semiconductor detector, comprising: The gamma rays emitted from different positions of the object to be detected are collimated by using the collimators in the collimator array; Multiple perovskite semiconductor detectors are used to detect gamma rays emitted from different positions of the object to be detected, and multiple multi-channel sensing signals are output; Extracting a plurality of first signals containing incident energy information and a plurality of second signals related to incident event time information from a plurality of multi-channel sensing signals using a signal readout circuit of a plurality of channels in a multi-channel front-end readout module; Performing analog-to-digital conversion on the plurality of first signals and the plurality of second signals using a data acquisition and processing module to obtain a plurality of first digital signals and a plurality of second digital signals; and correcting the plurality of first digital signals to obtain a plurality of corrected first digital signals; An upper computer is used to perform image reconstruction based on each corrected first digital signal and each second digital signal to obtain a distribution image of the radioactive element in the object to be detected.

[0018] The gamma-ray imaging device based on the perovskite semiconductor detector provided in this application has the following beneficial effects: 1. Metal halide perovskite semiconductors have outstanding optoelectronic properties and relatively low preparation costs, and the intrinsic defect tolerance of perovskite materials gives them excellent charge transport properties. Compared to the high purity requirements of cadmium zinc telluride (CZT) spectral-grade crystals, low-purity perovskite crystals can exhibit excellent gamma-ray resolution. Furthermore, low-cost large-scale production can be achieved based on melt-based controllable crystal growth technology. Therefore, this application considers the dual advantages of perovskite semiconductor detectors in terms of detection performance and economic performance and applies perovskite semiconductor detectors to the imaging field for the first time. Furthermore, considering that gamma rays will be emitted from all directions when the object to be detected is imaged, this application uses multiple collimators to construct a collimator array to collimate the gamma rays emitted from different positions of the object to be detected. On this basis, a detector array is designed using multiple perovskite semiconductor detectors to detect gamma rays emitted from different positions. Ultimately, the distribution of radioactive elements within the object to be detected is obtained based on the energy and quantity of gamma rays at different positions of the object to be detected. 2. When a perovskite semiconductor detector is directly used to replace other detectors in an existing imaging device, the signal readout circuit in the existing imaging device cannot fully read out the pulse signal output by the perovskite semiconductor detector. This signal loss problem will lead to errors in the distribution position of radioactive elements in the object to be detected, affecting the imaging quality. To this end, the present application uses a charge-sensitive preamplifier to detect and pre-amplify the weak multi-channel sensing signal generated by the detector, providing a relatively stable and appropriate amplitude target multi-channel sensing signal for subsequent processing, alleviating the signal amplitude uncertainty problem caused by the difference in charge collection time. Furthermore, since the output signal rise time of the perovskite semiconductor detector is long, the slow shaper can filter and shape the target multi-channel sensing signal, converting it into a waveform that is easier to process, extending the signal processing time, allowing more time for the charge to be collected, and reducing the ballistic loss caused by charge leakage. At the same time, the baseline recovery circuit is used to avoid the signal amplitude error caused by baseline drift, which helps to solve the problem of inaccurate energy spectrum caused by ballistic loss. Then, the peak detection and holding circuit is used to stably obtain the signal peak value, so as to obtain a signal that is more accurately related to the incident energy. The source follower is used to reduce the attenuation and distortion of the signal during transmission, ensuring that the signal can be stably transmitted to the subsequent circuit; at the same time, the fast shaper can first quickly determine the starting time characteristics of the signal, which helps to accurately identify the incident event in the presence of ballistic loss. Finally, the discriminator is used to determine whether the signal is a valid incident event signal, and eliminate interference signals such as noise. Finally, the monostable circuit is used to convert the rising edge of the valid signal time that exceeds the threshold into a stable pulse level, and accurately output the second signal related to the time information of the incident event, thereby improving the accuracy of the system's judgment of the incident event and compensating to a certain extent for the influence of ballistic loss on signal recognition. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein: Figure 1 This is a performance diagram of the perovskite semiconductor detector provided in this application; wherein, Figure 1 (a) is a schematic diagram showing the relationship between the crystal absorption efficiency and thickness of the perovskite semiconductor detector. Figure 1 (b) is a schematic diagram of the absorption efficiency of the crystal of the perovskite semiconductor detector under gamma-ray photon irradiation; Figure 2 The perovskite semiconductor detector provided in this application is compared with the traditional scintillator detector and the traditional semiconductor detector 99m Tc gamma-ray energy resolution comparison chart; Figure 3A schematic structural diagram of a gamma-ray imaging device based on a perovskite semiconductor detector provided in this application; Figure 4 Schematic diagram of the collimator type provided in this application; wherein, Figure 4 (a) is a schematic diagram of a pinhole collimator. Figure 4 (b) is a schematic diagram of a parallel hole collimator. Figure 4 (c) is a schematic diagram of a divergent collimator. Figure 4 (d) is a schematic diagram of the converging collimator; Figure 5 This is a schematic diagram of the arrangement of the first detector array provided in this application; wherein, Figure 5 (a) is a schematic diagram of the first detector array arranged in an arc shape. Figure 5 (b) is a schematic diagram of the first detector array of the dual-probe type. Figure 5 (c) is a schematic diagram of the first detector array with three probes. Figure 5 (d) is a schematic diagram of the first ring-shaped detector array; Figure 6 A schematic diagram of the arrangement of the first detector array and the second detector array provided in this application; Figure 7 A schematic diagram of the structure of the multi-channel front-end readout module provided in this application; Figure 8 Schematic diagram of the signal readout process of the perovskite semiconductor detector provided in this application; Figure 9 Schematic diagram of the imaging principle of the gamma-ray imaging device based on perovskite semiconductor detector provided in this application; Figure 10 Flowchart of the gamma-ray imaging method based on perovskite semiconductor detector provided in this application; Figure 11 This is a schematic diagram of projection imaging of a gamma-ray imaging device based on a perovskite semiconductor detector provided in Example 1 of the present application; wherein, Figure 11 (a) is a schematic diagram of imaging a point source by a gamma-ray imaging device based on a perovskite semiconductor detector provided in Example 1 of the present application. Figure 11 (b) is a schematic diagram of imaging a line source by a gamma-ray imaging device based on a perovskite semiconductor detector provided in Example 1 of the present application; Figure 12 This is a schematic diagram of the pixel energy signal amplitude distribution within each pixel in the gamma-ray imaging device based on the perovskite semiconductor detector provided in Example 1 of the present application; wherein, Figure 12 (a) is a schematic diagram of the pixel signal amplitude distribution within the first pixel. Figure 12 (b) is a schematic diagram of the pixel signal amplitude distribution within the second pixel. Figure 12 (c) is a schematic diagram of the pixel signal amplitude distribution within the third pixel. Figure 12 (d) in the figure is a schematic diagram of the pixel signal amplitude distribution within the fourth pixel. Figure 12 (e) in the figure is a schematic diagram of the pixel signal amplitude distribution within the fifth pixel. Figure 12 (f) in the figure is a schematic diagram of the pixel signal amplitude distribution within the sixth pixel. Figure 12 (g) in the figure is a schematic diagram of the pixel signal amplitude distribution within the seventh pixel. Figure 12 (h) in the figure is a schematic diagram of the pixel signal amplitude distribution within the eighth pixel. Figure 12 (i) in the figure is a schematic diagram of the pixel signal amplitude distribution within the ninth pixel. Figure 12 (j) in the figure is a schematic diagram of the pixel signal amplitude distribution within the tenth pixel. Figure 12 (k) in the figure is a schematic diagram of the pixel signal amplitude distribution within the eleventh pixel. Figure 12 (l) in the figure is a schematic diagram of the pixel signal amplitude distribution within the twelfth pixel. Figure 12 (m) in the figure is a schematic diagram of the pixel signal amplitude distribution within the thirteenth pixel. Figure 12 (n) in the figure is a schematic diagram of the pixel signal amplitude distribution within the fourteenth pixel. Figure 12 (o) in the figure is a schematic diagram of the pixel signal amplitude distribution within the fifteenth pixel. Figure 12 (p) in FIG. 1 is a schematic diagram of the pixel signal amplitude distribution within the sixteenth pixel; Figure 13 Schematic diagram of the gamma-ray response performance characterization of the gamma-ray imaging device based on the perovskite semiconductor detector provided in Example 1 of the present application; wherein, Figure 13 (a) is collected by one of the pixel electrodes 99m The statistical histogram of the Tc gamma-ray energy signal shows that the perovskite detector has high energy resolution. Figure 13 (b) shows the energy resolution and full energy peak position of each channel of the perovskite detector, indicating that the multi-channel response of the perovskite detector is uniform; Figure 14 This is a schematic diagram of 16-way pixel peak area counting in point source imaging provided in Example 1 of the present application; wherein, Figure 14 (a) is the 16-channel pixel peak area counting statistics table in point source imaging. Figure 14 (b) is the distribution diagram of 16-channel pixel peak counts in point source imaging; Figure 15 This is a schematic diagram of 16-channel pixel peak area counting in line source imaging provided in Example 1 of the present application; wherein, Figure 15 (a) is the 16-channel pixel peak area counting statistics table in line source imaging. Figure 15(b) is the distribution diagram of 16-channel pixel peak counts in line source imaging; Figure 16 This is a schematic diagram of imaging a prosthesis using a gamma-ray imaging device based on a perovskite semiconductor detector in Example 2 of the present application; wherein, Figure 16 (a) is a schematic diagram of the structure of imaging the prosthesis using a gamma-ray imaging device based on a perovskite semiconductor detector. Figure 16 (b) is the diameter of the prosthesis is 0.7mm 99m Tc column source, Figure 16 (c) in 99m Schematic diagram of the energy spectrum collected during Tc prosthesis imaging; Figure 17 This is a schematic diagram of the imaging results obtained in Example 2 of the present application; wherein, Figure 17 (a) shows the three 0.7 mm diameter cylindrical sources in the Derenzo prosthesis. 99m Tc gamma-ray single-photon image, Figure 17 (b) in the figure is the counting profile of the gamma-ray image; Explanation of the reference numerals in the specification: 1. Collimator array; 11. Collimator; 2. First detector array; 21. Perovskite semiconductor detector; 3. Multi-channel front-end readout module; 31. Charge-sensitive preamplifier; 32. First signal extraction circuit; 321. Slow shaper; 322. Baseline recovery circuit; 323. Peak detection and holding circuit; 324. Source follower; 33. Second signal extraction circuit; 331. Fast shaper; 332. Digital-to-analog converter; 333. Discriminator; 334. Monostable circuit; 4. Data acquisition and processing module; 41. Digital-to-analog converter; 42. Analog-to-digital converter; 5. Host computer; 6. Object to be detected; 7. Second detector array. DETAILED DESCRIPTION

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0021] Metal halide perovskite semiconductors have become a hot topic in the field of radiation detection materials due to their outstanding optoelectronic properties and relatively low production costs. The intrinsic defect tolerance of perovskite materials gives them excellent charge transport properties. Compared to the high purity requirement (~7N) for spectroscopy-grade CdZnTe crystals, perovskite crystals with a purity of ~5N can exhibit excellent gamma-ray resolution. In 2021, perovskite pixel-type semiconductor detectors achieved a 1.4% energy resolution for 662 keV gamma rays. By 2025, perovskite semiconductor detectors based on bipolar carrier transport achieved a 1.3% energy resolution for 662 keV gamma rays, comparable to commercial CdZnTe semiconductor detectors. Furthermore, controlled crystal growth technology based on the melt method allows for low-cost, large-scale production. The price of spectroscopy-grade perovskite crystals is expected to be comparable to that of commercial sodium iodide crystals and significantly lower than that of CdZnTe semiconductors. Based on this, compared with traditional scintillators and semiconductor detectors, perovskite semiconductor detectors have significant advantages in detection performance and economic performance. However, there is currently no relevant research on gamma-ray imaging devices based on perovskite semiconductor detectors.

[0022] This application considers the defects of traditional semiconductor detectors in gamma-ray imaging and the advantages of perovskite semiconductor detectors, and considers the application of perovskite semiconductor detectors in gamma-ray imaging devices for the first time. Figure 1 The figure shows the performance of the perovskite semiconductor detector provided by the present application; wherein, Figure 1 (a) is a schematic diagram showing the relationship between the crystal absorption efficiency and thickness of the perovskite semiconductor detector. Figure 1 (b) is a schematic diagram of the absorption efficiency of the crystal of the perovskite semiconductor detector under gamma-ray photon irradiation; Figure 2 A comparison chart of the gamma-ray energy resolution of the perovskite semiconductor detector provided in this application, traditional scintillator detectors, and traditional semiconductor detectors.

[0023] Combine Figure 1 and Figure 2 It can be seen that the commonly used single photon gamma ray imaging system 99m For example, for gamma rays with a Tc 141 keV absorption efficiency of 90%, the traditional scintillator NaI (Tl) crystal requires a thickness of 9.5 mm and an energy resolution of 10%. Cadmium zinc telluride semiconductors require a thickness of 7.5 mm and an energy resolution of 6%. However, the perovskite semiconductor CsPbBr3 requires a thickness of only 5 mm, achieving an energy resolution of 2-4%, and exhibiting a high absolute peak photoelectric efficiency. Collimator designs tailored to specific application scenarios can further optimize the imaging system's spatial resolution and imaging efficiency, enhancing overall performance and meeting clinical needs such as high-precision nuclear medicine imaging.

[0024] However, the present applicant found that when perovskite semiconductor detectors are directly used to replace other detectors in existing imaging devices, the signal readout circuit is unable to fully read out the pulse signal output by the perovskite semiconductor detector, that is, the measured signal amplitude is too small, resulting in some effective signals being misjudged as noise due to their low amplitude, causing counting losses. This signal loss problem will lead to incorrect positioning of the distribution position of radioactive elements in the object to be detected, affecting the imaging quality.

[0025] Through research, the present application found that the above-mentioned signal loss problem is because the signal readout circuits in the existing imaging devices are all designed based on cadmium zinc telluride semiconductor detectors, and the mobility of cadmium zinc telluride semiconductor detectors is relatively large, that is, electrons can quickly move to the electrodes before recombination, the signal collection efficiency is relatively high, and the rising edge of the output pulse signal is extremely fast. Therefore, the ASIC chip used in the signal readout circuit in the existing imaging device needs to be matched with a faster pulse shaping circuit to ensure accurate reading of ns-level fast signals. The perovskite semiconductor detector belongs to a slow signal detection material, and the rising edge of the pulse signal it outputs is relatively slow. When the event constant of the signal readout circuit is much smaller than the rise time of the slow signal, it is equivalent to the slow signal not being fully formed, and the signal readout circuit has completed the signal readout process, resulting in the readout signal pulse amplitude being much smaller than the actual pulse signal amplitude, that is, signal loss. Therefore, when designing a gamma-ray imaging device based on a perovskite semiconductor detector, how to solve the signal loss problem to ensure imaging quality is another technical problem that needs to be solved in this application.

[0026] In order to solve the above technical problems, the embodiment of the present application provides a gamma ray imaging device based on a perovskite semiconductor detector, such as Figure 3 The figure shows a schematic structural diagram of a gamma-ray imaging device based on a perovskite semiconductor detector provided in an embodiment of the present application. The device specifically includes a collimator array 1, a first detector array 2, a multi-channel front-end readout module 3, a data acquisition and processing module 4 and a host computer 5.

[0027] The geometric center of the collimator array 1 is aligned with the center of the object to be detected 6, and is used to collimate the gamma rays emitted from different positions of the object to be detected using the collimators 11 in the collimator array 1, so as to determine the incident direction of the rays.

[0028] Furthermore, the collimator 11 can be a pinhole collimator, a parallel hole collimator, a diverging collimator or a converging collimator, wherein the shape of the hole in the parallel hole collimator can be circular, hexagonal or other shapes. Figure 4 The figure shows a schematic diagram of the collimator type provided by this application; wherein, Figure 4 (a) is a schematic diagram of a pinhole collimator. Figure 4 (b) is a schematic diagram of a parallel hole collimator. Figure 4(c) is a schematic diagram of a divergent collimator. Figure 4 (d) in the figure is a schematic diagram of a converging collimator.

[0029] The first detector array 2 includes a plurality of perovskite semiconductor detectors 21, and a plurality of pixelated electrodes of each perovskite semiconductor detector 21 are aligned with a plurality of collimators 11 in the collimator array 1; the first detector array 2 is used to detect gamma rays emitted from different positions of the object to be detected 6 using the plurality of perovskite semiconductor detectors 21, and output a plurality of multi-channel sensing signals.

[0030] Optionally, the shapes of the collimator array 1 and the first detector array 2 can be designed according to the shape of the object to be detected 6, for example: an arc-shaped detector array for imaging of a specific organ, a dual-probe detector array for whole-body imaging, etc. Figure 5 The figure shows the arrangement diagram of the first detector array provided by the present application; wherein, Figure 5 (a) is a schematic diagram of the first detector array arranged in an arc shape. Figure 5 (b) is a schematic diagram of the first detector array of the dual-probe type. Figure 5 (c) is a schematic diagram of the first detector array with three probes. Figure 5 (d) is a schematic diagram of the first ring-shaped detector array.

[0031] The multi-channel front-end readout module 3 is connected to the first detector array 2, and is used to use the signal readout circuits of multiple channels to extract multiple first signals containing incident energy information and multiple second signals related to the time information of the incident event from the multiple multi-channel sensing signals.

[0032] The data acquisition and processing module 4 is connected to the multi-channel front-end readout module 3, and is used to perform analog-to-digital conversion on multiple first signals and multiple second signals to obtain multiple first digital signals and multiple second digital signals; and correct the multiple first digital signals to obtain multiple corrected first digital signals.

[0033] The host computer 5 is in communication with the data acquisition and processing module 4 and is used to perform image reconstruction based on each corrected first digital signal and each second digital signal to obtain a distribution image of the radioactive element in the object to be detected 6 .

[0034] Specifically, the perovskite semiconductor of the perovskite semiconductor detector 21 in the present application is a three-dimensional perovskite, a two-dimensional perovskite, a zero-dimensional perovskite or an antiperovskite.

[0035] Among them, the three-dimensional perovskite is A1B1X13, A1 is one or more of Na, K, Rb, Cs, Cu, T1, H3O; B1 is one or more of Pb, Si, Ge, Sn, Mg, Ca, Sr, Ba, Zn, Cd, Hg; X1 is one or more of F, Cl, Br, I, BF4, HCOO, OH, CN, SCN, NCS, SH, NO3, H2POO.

[0036] The two-dimensional perovskite is T1PbI3 or A23B22X29, where A2 is one or two of Cs and Rb; B2 is one or two of Sb and Bi; and X2 is one or more of F, Cl, Br, and I.

[0037] Zero-dimensional perovskites are Cs3Bi2I9, Cs2TeI6, Cs2TeBr6 or Cs2TeCl6.

[0038] Antiperovskite is Hg3Se2Br2 or T1Sn2I5.

[0039] Furthermore, the perovskite semiconductor detector 21 is a planar array pixel detector, with a pixel shape of square, circular, or hexagonal, and a pixel size of 0.01 mm to 100 mm. Alternatively, the perovskite semiconductor detector 21 is a strip-shaped one-dimensional array detector, with a strip size of 0.01 mm to 100 mm.

[0040] Furthermore, the thickness of the perovskite semiconductor detector 21 is 0.5 mm to 50 mm.

[0041] Specifically, the perovskite semiconductor detector 21 of the present application can realize the detection and imaging of gamma rays of different energies (50-700keV), which can meet the requirements of 99m Tc, 177 Lu, 131 I. 125 I. 90 The detection needs of gamma photons generated by the decay of commonly used clinical nuclides such as Y; the signal types collected by the perovskite detector are holes or electrons.

[0042] Furthermore, in order to meet the demand for higher energy gamma ray detection in the integrated process of radiological diagnosis and treatment, a multi-layer detector array can also be used. Specifically, in some embodiments of the present application, the gamma ray imaging device based on perovskite semiconductor detectors also includes a second detector array 7.

[0043] The second detector array 7 is arranged on the side of the first detector array 2 away from the collimator array 1, and includes multiple perovskite semiconductor detectors 21, which are used to detect gamma rays emitted from different positions of the object to be detected 6 using the multiple perovskite semiconductor detectors 21, and output multiple multi-channel sensing signals, so that the multi-channel front-end readout module 3, the data acquisition and processing module 4 and the host computer 5 can obtain the distribution image of the radioactive elements in the object to be detected 6 based on the multi-channel sensing signals output by the first detector array 2 and the second detector array 7.

[0044] like Figure 6 The figure shows a schematic diagram of the arrangement of the first detector array 2 and the second detector array 7 provided in the present application. During the data acquisition process, after the incident photons pass through the annular collimator array 1, they are respectively emitted to the inner first detector array 2 and the outer second detector array 7. The perovskite semiconductor detectors 21 in the inner and outer detector arrays can synchronously capture the incident photons to realize parallel data acquisition, thereby significantly improving the detection sensitivity of the device and the detection efficiency of high-energy rays.

[0045] Furthermore, in some embodiments of the present application, the host computer 5 is connected to the collimator array 1 and the first detector array 2, and is used to control the collimator array 1 and the first detector array 2 to rotate around the object to be detected 6 to collect gamma rays emitted from multiple projection angles of the object to be detected 6.

[0046] When the perovskite semiconductor detectors 21 in the first detector array 2 are densely arranged in a ring shape around the periphery of the object to be detected 6, each perovskite semiconductor detector 21 can collect gamma rays emitted from multiple projection angles (i.e., various positions) of the object to be detected. However, when the multiple perovskite semiconductor detectors 21 in the first detector array 2 form a dual-probe or triple-probe detector, the gamma rays emitted from different projection angles of the object to be detected 6 cannot be covered. Therefore, the collimator array 1 and the first detector array 2 can be controlled by the host computer 5 to rotate around the object to be detected 6.

[0047] Specifically, the collimator array 1 and the first detector array 2 can rotate synchronously, or one of them can be fixed and the position of the other can be adjusted according to changes in the imaging part, thereby adapting to objects 6 to be detected of different sizes and structures.

[0048] For example, in order to obtain complete radioactivity distribution information, the first detector array 2 can perform a 360° or 180° rotation scan around the object to be detected 6 to collect projection data at multiple angles, generally collecting 60-120 projection angles, and the collection time for each projection angle is 10-20 seconds for image reconstruction.

[0049] Furthermore, although the above-mentioned gamma-ray imaging device based on the perovskite semiconductor detector 21 solves the problems of high cost and low resolution of the imaging device of the traditional semiconductor detector, there is a problem of low imaging quality caused by signal loss. For this reason, the present application designs an ASIC chip dedicated to signal reading of the perovskite semiconductor detector 21 as a multi-channel front-end readout module 3. For example, the number of channels of the multi-channel front-end readout module 3 can be 128 or 256, so that multiple multi-channel sensing signals can be collected and output.

[0050] like Figure 7 1 is a schematic structural diagram of a multi-channel front-end readout module 3 provided in the present application, which specifically includes a charge-sensitive preamplifier 31 , a first signal extraction circuit 32 and a second signal extraction circuit 33 .

[0051] The charge-sensitive preamplifier 31 is used to detect and pre-amplify the sensing signal to obtain a target sensing signal.

[0052] The first signal extraction circuit 32 is connected to the charge-sensitive preamplifier 31 and includes a slow shaper 321, a baseline recovery circuit 322, a peak detection and holding circuit 323, and a source follower 324 connected in series. It is used to filter the target sensing signal, restore the baseline, detect and hold the amplitude, and buffer the signal, and output a first signal containing incident energy information.

[0053] The second signal extraction circuit 33 is connected to the charge-sensitive preamplifier 31 , and includes a fast shaper 331 , a digital-to-analog converter 332 , a discriminator 333 and a monostable circuit 334 .

[0054] The fast shaper 331 is connected to the charge-sensitive preamplifier 31 and is used to perform fast waveform shaping on the target multi-channel sensing signal.

[0055] The digital-to-analog converter 332 is used to generate a threshold voltage signal.

[0056] Specifically, the digital-to-analog converter 332 may be connected to the host computer 5 and generate a threshold voltage signal based on the control quality of the host computer 5 .

[0057] The discriminator 333 is connected to the fast shaper 331 and the digital-to-analog converter 332 and is used to compare the target multi-channel sensing signal output by the fast shaper 331 with the threshold voltage signal, thereby identifying and outputting an over-threshold signal in the target multi-channel sensing signal.

[0058] The monostable circuit 334 is connected to the discriminator 333 and is used to generate a stable pulse signal with the starting moment of the over-threshold signal as the starting point and the starting moment of the output signal of the peak detection and holding circuit 323 as the end point when the discriminator 333 outputs an over-threshold signal. The stable pulse signal is the second signal related to the time information of the incident event.

[0059] Specifically, by using a high gain (such as 1~5.0mV / fC) and a long time constant ( ) detects and pre-amplifies the sensing signal from the perovskite semiconductor detector 21, which can improve the signal-to-noise ratio of the sensing signal. In addition, the multi-channel front-end readout module 3 provided in this application adopts a long forming time design (e.g., 1 to 30 μs or more), which effectively reduces the ballistic loss problem caused by incomplete carrier collection. In addition, the multi-channel front-end readout module 3 designed in this application can process gamma photons with an energy range of 50-600 keV and a single photon count rate of 1 cps to 100 Kcps. It can operate in wide energy window mode (multi-nuclide imaging) and single energy mode (single nuclide), and has selectable gain, which can meet the clinical requirements of multi-nuclide imaging and single nuclide imaging.

[0060] Furthermore, due to the differences in the linear attenuation coefficients of gamma photons for different objects to be detected 6, such as human organs, bones, muscles and fat, different degrees of absorption and scattering will occur during the propagation of photons in the object to be detected 6, resulting in the energy of the photons emitted by the object to be detected 6 being significantly attenuated or even completely lost before reaching the perovskite semiconductor detector 21. This phenomenon makes the shallow tissue of the object to be detected 6 close to the surface of the perovskite semiconductor detector 21 appear brighter, while the deeper parts (when the object to be detected 6 is the human body, the deeper parts such as the posterior wall of the myocardium and the deep brain nuclei) appear darker due to being shielded by the surface tissue. Therefore, the signal needs to be corrected before reconstructing the signal.

[0061] Furthermore, the data acquisition and processing module 4 includes an analog-to-digital converter 41 and an FPGA 42 .

[0062] The analog-to-digital converter 41 is connected to the multi-channel front-end readout module 3 and is used to convert the multiple first signals and the multiple second signals into multiple first digital signals and the multiple second digital signals.

[0063] The FPGA 42 is communicatively connected to the analog-to-digital converter 41 and the host computer 5, and is used to receive multiple first digital signals and multiple second digital signals after analog-to-digital conversion, and based on the control signal of the host computer 5, use the energy attenuation correction algorithm to correct each first digital signal, and use the depth correction algorithm based on the second digital signal and the internal weight potential distribution model of the perovskite semiconductor detector 21 to further correct each first digital signal to compensate for the signal amplitude loss caused by the weight potential loss of the internal structure of the perovskite semiconductor detector 21; and transmit the multiple corrected first digital signals and multiple second digital signals to the host computer 5.

[0064] After completing the above correction, the number of incident photons at the current scanning angle can be obtained by screening the target ray energy window, which helps to increase the count of the full-energy peak selection window and improve the image signal-to-noise ratio.

[0065] Furthermore, the host computer 5 specifically includes an image reconstruction module, which is used to receive each corrected first digital signal and each second digital signal, and use a filtered back projection algorithm and an iterative reconstruction algorithm (such as an expectation maximization algorithm) to perform three-dimensional image reconstruction on the received multiple signals to obtain the distribution of radioactive elements in the object to be detected 6.

[0066] Specifically, the filtered back projection algorithm, a classic reconstruction method for computed tomography, has been widely used in various imaging systems by effectively solving the image quality degradation problem caused by overweighting of low-frequency signals in Fourier transform frequency domain interpolation. Specifically, it includes: Step 1: In the rotating coordinate system, the two-dimensional Fourier transform F(u,v) of the two-dimensional image f(x,y) is expressed as: , in, represents the angle between the integral path method and the x-axis; represents frequency domain variables.

[0067] Step 2: Since the computed tomography is a rotation system, according to its symmetry , so in the frequency domain we have , on this basis, the integral path is split, and according to the central slice theorem, the formula in step 1 can be converted into: , in, Represents the frequency response function, also known as the ramp filter function; It is a projection The one-dimensional Fourier transform of dimension s.

[0068] Step 3: The ideal impulse response of the ramp filter function cannot be realized in the actual algorithm. It is usually achieved by defining a frequency in the frequency domain. External, energy-zero finite bandwidth window function , and The actual filter used by the reconstruction algorithm , also known as the filter kernel.

[0069] The filter kernel and window function are expressed as: , , By changing the cutoff frequency of the window function, the filtered reconstructed image can have different smoothness levels, thereby adjusting the balance between image noise and structural resolution. The filtered projection can be obtained by aligning and performing inverse Fourier transform to obtain the current angle The filtered back-projection corresponding to the projection data is used to reconstruct the data, and then all the projection data are back-projected angle by angle and accumulated to obtain the final reconstructed image.

[0070] The expectation-maximization (EM) algorithm, a mainstream iterative image reconstruction method, is based on a random parameter estimation framework. This algorithm demonstrates significant advantages in tomographic image reconstruction systems, particularly when projection data is subject to strong noise or when acquisition angles are incomplete. Based on parameter estimation theory, the EM algorithm can still achieve effective reconstruction, making it one of the core algorithms in the field of tomographic imaging. This algorithm, based on the statistical properties of photon radiation following a Poisson random process, effectively compensates for image blurring caused by factors such as scattering and attenuation.

[0071] Specifically, in tomography, the photon counts generated by the radiation source are (Projected data) follows a Poisson distribution: ,in, is the expected value of the random variable.

[0072] For an imaging problem In terms of is the projected data vector, is the total number of projections, is the tomographic image vector to be reconstructed, N is the total number of pixels in the image; is the system matrix of image reconstruction, which characterizes the spatial response relationship). The number of photons passing through each image pixel is an independent Poisson random variable, and each measurement value can be regarded as the sum of these variables, that is, , and then calculate all random variables The joint distribution function of , we can get a likelihood function: , Taking the logarithm of the likelihood function and omitting the constant term, we get the objective function. In order to find the maximum likelihood solution , that is, to find the maximum value of the following objective function: , Since this nonlinear equation has no analytical solution, its approximate solution can only be obtained through iteration. At the same time, the expectation maximization (EM) framework is used to transform the random variables in the objective function into Replace it with its expected value, that is, .

[0073] Finally, find the maximum value of the new objective function and solve it , we can get the final MLEM algorithm in image reconstruction: , Combine the above formula with the actual imaging matrix Combined, we get the MLEM algorithm formula: .

[0074] like Figure 8 The figure shows a schematic diagram of the signal readout process of the perovskite semiconductor detector provided in this application. As can be seen from the figure, the multi-channel front-end readout module (ASIC in the figure) reads the multi-channel sensing signal output by the perovskite semiconductor detector, and its output signal line is converted into a digital signal through the analog-to-digital converter ADC. The host computer controls the FPGA to perform data correction on the digital signal, and finally the host computer processes the digital signal obtained by the FPGA and realizes image reconstruction.

[0075] like Figure 9 The figure shows a schematic diagram of the imaging principle of the gamma-ray imaging device provided by the present application. By injecting a radionuclide-labeled drug into the object to be detected, the gamma rays generated by its decay are incident on the perovskite semiconductor detector array after being screened by the collimator array, and electron-hole pairs are generated in the crystal of the perovskite semiconductor detector. Under the action of the external electric field, the electrons and holes drift to the corresponding electrodes respectively, forming a multi-channel sensing signal. The multi-channel sensing signal is read, filtered, amplified and signal corrected using a multi-channel front-end readout module, data acquisition and processing, and a host computer to obtain the energy and spatial position information of each detection event and generate projection information in a certain incident direction. The host computer controls the rotation of the detector to collect projection data at different angles. Finally, a three-dimensional tomographic image is reconstructed based on the projection information of multiple incident directions to obtain a cross-sectional image, a coronal image and a three-dimensional reconstructed image of the distribution of radioactive elements in the object to be detected.

[0076] Based on the gamma-ray imaging device based on the perovskite semiconductor detector provided in the above embodiment, the embodiment of the present application further provides a gamma-ray imaging method based on the perovskite semiconductor detector, such as Figure 10 As shown, the method specifically includes: S10: collimating the gamma rays emitted from different positions of the object to be detected by using each collimator in the collimator array.

[0077] S20: Utilize multiple perovskite semiconductor detectors to detect gamma rays emitted from different positions of the object to be detected, and output multiple multi-channel sensing signals.

[0078] S30: extracting a plurality of first signals containing incident energy information and a plurality of second signals related to incident event time information from a plurality of multi-channel sensing signals using a signal readout circuit of a plurality of channels in a multi-channel front-end readout module.

[0079] S40: performing analog-to-digital conversion on the plurality of first signals and the plurality of second signals using a data acquisition and processing module to obtain a plurality of first digital signals and a plurality of second digital signals, and correcting the plurality of first digital signals to obtain a plurality of corrected first digital signals;

[0080] S50: Using a host computer to perform image reconstruction based on each corrected first digital signal and each second digital signal, to obtain a distribution image of the radioactive element in the object to be detected.

[0081] The gamma-ray imaging device based on the perovskite semiconductor detector is further explained below through multiple embodiments: Example 1 of the present application provides a gamma-ray imaging device based on a perovskite semiconductor detector, which is a pixel-type perovskite semiconductor detector with a size of 7×7×3.8 mm. 3 , the number of pixels is 4×4, the pixel size is 1.0 mm, and the pixel gap is 0.2 mm.

[0082] In the point source and line source imaging studies, the collimator used was made of tungsten with a total thickness of 3.5 mm, a hole collimation hole diameter of 0.5 mm, a line collimation hole width of 0.5 mm, and a length of 6 mm. 99m TcO4 solution is encapsulated in a capillary and placed below the collimation hole prepared from tungsten as a radiation source. The radiation source and the collimation hole are placed as a whole below the perovskite pixel detector.

[0083] like Figure 11 FIG. 1 is a schematic diagram of projection imaging of a gamma-ray imaging device based on a perovskite semiconductor detector provided in Example 1 of the present application; wherein, Figure 11 (a) is a schematic diagram of imaging a point source by a gamma-ray imaging device based on a perovskite semiconductor detector provided in Example 1 of the present application. Figure 11 (b) is a schematic diagram of imaging a line source by a gamma-ray imaging device based on a perovskite semiconductor detector provided in Example 1 of the present application.

[0084] A 200 V bias voltage is applied to the perovskite pixel detector, and a multi-channel front-end readout module is used to collect the pulse signals of 16 pixel electrodes in real time. The data processing system shapes and further amplifies the pulse signals to obtain the amplitude information. The gamma events incident on the 16 pixels over a period of time are counted, and the amplitude distribution of each pixel signal is accumulated, as shown in the following figure: Figure 12 (a) to (p) in the middle are schematic diagrams of the pixel signal amplitude distribution within 16 pixels.

[0085] Figure 13 FIG. 1 is a schematic diagram showing the gamma-ray response performance characterization of a gamma-ray imaging device based on a perovskite semiconductor detector provided in Example 1 of the present application; wherein, Figure 13 (a) is collected by one of the pixel electrodes 99m The statistical histogram of the Tc gamma-ray energy signal shows that the perovskite semiconductor detector has high energy resolution. Figure 13 (b) in the figure shows the energy resolution and full-energy peak position of each channel of the perovskite detector, indicating that the multi-channel response of the perovskite detector is uniform.

[0086] from Figure 13 It can be seen from the figure that under flooding source irradiation, the 16-way pixel electrode pair 99m The energy resolution of Tc 141 keV gamma rays is between 2-3%, and the full-energy peak address ranges from 601 to 609, with a small difference. This indicates that the energy spectrum response of each pixel is uniform and the full-energy peak efficiency is high.

[0087] Based on its high energy resolution response, the energy window range is set to 141±5.64 keV, and the counts of 16 pixel electrodes within the energy window range are counted, as shown in the following example: Figure 14 The figure shows a schematic diagram of 16-way pixel peak area counting in point source imaging; Figure 14 (a) is the 16-channel pixel peak area counting statistics table in point source imaging. Figure 14 (b) is the distribution diagram of 16-way pixel peak counts in point source imaging. Figure 14 It can be seen that only the 6th pixel presents a high full-energy peak count, the 2nd pixel full-energy peak area shows a small number of counts, and the count rates in other areas are low due to occlusion. Therefore, based on the distribution of the full-energy peak counts of the 16 pixels, it is inferred that the hole collimator is located in the 6th pixel.

[0088] According to the same method as the aforementioned hole collimation hole test, the line collimation hole is placed under the perovskite semiconductor detector, and the energy spectrum test is performed on each pixel at a voltage of 200 V. The counts of the 16 pixel electrodes within the energy window range are counted, as shown in the figure. Figure 15 The figure shows a schematic diagram of 16-channel pixel peak area counting in line source imaging; Figure 15 (a) is the 16-channel pixel peak area counting statistics table in line source imaging. Figure 15 (b) is the distribution diagram of 16-way pixel peak counts in line source imaging. Figure 15 As can be seen from the figure, based on the count distribution of 16 pixel electrodes in the full energy peak area, only the third column of pixels shows a high count response, while the remaining pixels have almost no counts at the full energy peak due to the tungsten blocking. Therefore, it can be inferred that the opening position of the line collimator is located below the third column of pixels to achieve 99m Projection imaging of Tc nuclide line source.

[0089] The calculation formula for the known radioactivity A is: , in, is the decay constant, N is the number of radioactive nuclides, is the initial radioactivity.

[0090] In the imaging studies of hole collimators and line collimators, the radioactivity of the radiation source was calculated to be 12840 Bq and 6440 Bq, respectively, based on the dimensions of the collimators. Using the known activity of the radiation source, the irradiation time, and the peak area counts statistically measured in the experiment, it can be estimated that the detection efficiency of the perovskite semiconductor detector for hole collimator and line collimator radiation sources under specific conditions is 0.14% and 0.15% cps / Bq, respectively. These are superior to scintillator-based gamma-ray detection systems and comparable to currently commercially available CZT semiconductor gamma-ray imaging systems, which is of great significance to nuclear medicine imaging equipment.

[0091] like Figure 16 As shown, Example 2 of the present application uses a gamma-ray imaging device based on a perovskite semiconductor detector to image the prosthesis.

[0092] A certain activity of Na 99m TcO4 solution was injected into the three 0.7 mm diameter columns of the Derenzo prosthesis, and a parallel hole collimator was placed above it. The distance between the radiation source and the collimator was 2.05 cm. Figure 16 (a) and Figure 16 As shown in (b) in .

[0093] The pulse signal output by the pixel electrode at each position is collected and shaped and further amplified by the data processing system to accumulate the energy spectrum, such as Figure 16As shown in (c), the counts within the 141±5.64 keV energy window are counted to obtain images of peak area counts at different positions.

[0094] like Figure 17 The figure shows a schematic diagram of the imaging results obtained in the embodiment of the present application, wherein: Figure 17 (a) shows the three 0.7 mm diameter cylindrical sources in the Derenzo prosthesis. 99m Tc gamma-ray single-photon image, Figure 17 (b) in the figure is the counting profile of the gamma-ray image. Based on the half-peak width of the counting profile of the gamma-ray image, its spatial resolution can be obtained to be 3.2 mm~3.8 mm.

[0095] The gamma-ray imaging device designed in this application, based on a perovskite semiconductor detector, features a simple fabrication process and high defect tolerance, enabling high yields of large-volume, spectral-grade crystals. Compared to traditional semiconductor materials like cadmium zinc telluride (CZT), perovskite materials offer significant cost advantages, reducing overall device manufacturing costs and promoting the widespread and widespread application of room-temperature semiconductor detectors in fields such as nuclear medicine imaging.

[0096] At the same time, since perovskite semiconductor detectors have excellent energy resolution and high absolute light peak efficiency, they can more accurately distinguish gamma photon energy and effectively suppress scattering artifacts. Therefore, the gamma-ray imaging device provided in this application can significantly shorten the scanning time while ensuring image quality, thereby improving imaging efficiency and reducing radiation exposure.

[0097] In addition, this application designs a multi-channel front-end readout module based on the characteristics of perovskite semiconductor detectors, which can not only realize real-time acquisition and processing of multi-channel signals, but also combine digital shaping and amplitude extraction algorithms to help improve energy spectrum resolution, enhance the ability to identify gamma photons of different energies, and realize multi-nuclide imaging.

[0098] Finally, the gamma-ray imaging device designed in this application has a compact structure, few moving parts, high overall stability and reliability, and significant cost advantages. It is not only suitable for large-area clinical imaging applications (such as whole-body bone imaging), but is also particularly suitable for scenarios with high requirements on equipment size and portability, such as bedside imaging, specific organ imaging, vehicle-mounted mobile equipment, and primary medical institutions, etc., which will help promote the popularization and implementation of high-performance semiconductor gamma imaging technology in diverse application environments.

[0099] It is worth noting that thanks to the excellent absorption efficiency and detection performance of perovskite semiconductor materials, as well as the multi-layer annular detector array structure used in some embodiments of the present application, efficient collection of high-energy gamma rays can be achieved; through the coordinated work of the inner and outer detection layers, the detection sensitivity and imaging efficiency are greatly improved, which is particularly suitable for the precise imaging needs of nuclides such as Lu-177 in nuclear medicine, and helps promote the development of molecular imaging technology in the integration of diagnosis and treatment applications, and promotes the integration of radiological diagnosis and treatment.

[0100] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0101] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0102] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0103] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0104] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A gamma-ray imaging device based on a perovskite semiconductor detector, characterized in that: include: A collimator array, the geometric center of which is aligned with the center of the object to be detected, and is used to collimate gamma rays emitted from different positions of the object to be detected using each collimator in the collimator array; a first detector array comprising a plurality of perovskite semiconductor detectors, wherein a plurality of pixelated electrodes of each perovskite semiconductor detector are aligned with a plurality of collimators in a collimator array; It is used to detect gamma rays emitted from different positions of the object to be detected using multiple perovskite semiconductor detectors and output multiple multi-channel sensing signals; a multi-channel front-end readout module connected to the first detector array and configured to extract, from the plurality of multi-channel sensing signals, a plurality of first signals containing incident energy information and a plurality of second signals related to incident event time information using a plurality of channel signal readout circuits; a data acquisition and processing module connected to the multi-channel front-end readout module, configured to perform analog-to-digital conversion on the plurality of first signals and the plurality of second signals to obtain a plurality of first digital signals and a plurality of second digital signals; and to correct the plurality of first digital signals to obtain a plurality of corrected first digital signals; The host computer is in communication with the data acquisition and processing module and is used to perform image reconstruction based on each corrected first digital signal and each second digital signal to obtain a distribution image of the radioactive element in the object to be detected.

2. The gamma-ray imaging device based on a perovskite semiconductor detector according to claim 1, characterized in that: Each signal readout circuit includes: A charge-sensitive preamplifier is used to detect and pre-amplify the multi-channel sensing signal to obtain the target multi-channel sensing signal; A first signal extraction circuit is connected to the charge-sensitive preamplifier and includes a slow shaper, a baseline restoration circuit, a peak detection and holding circuit, and a source follower connected in series, and is used to filter, restore the baseline, detect and hold the amplitude, and buffer the target multi-channel sensing signal, and output a first signal containing incident energy information; The second signal extraction circuit is connected to the charge-sensitive preamplifier and includes: A fast shaper, connected to the charge-sensitive preamplifier, is used to perform fast waveform shaping on the target multi-channel sensing signal; a digital-to-analog converter for generating a threshold voltage signal; a discriminator connected to the fast shaper and the digital-to-analog converter, and configured to compare the target multi-channel sensing signal output by the fast shaper with the threshold voltage signal, thereby discriminating and outputting an over-threshold signal in the target multi-channel sensing signal; The monostable circuit is connected to the discriminator and is used to generate a stable pulse signal with the starting time of the threshold-crossing signal as the starting point and the starting time of the output signal of the peak detection and holding circuit as the end point when the discriminator outputs the threshold-crossing signal, and output a second signal related to the time information of the incident event.

3. The gamma-ray imaging device based on a perovskite semiconductor detector according to claim 1, characterized in that: The perovskite semiconductor of the perovskite semiconductor detector is a three-dimensional perovskite, a two-dimensional perovskite, a zero-dimensional perovskite or an antiperovskite; Wherein, the three-dimensional perovskite is A1B1X13, A1 is one or more of Na, K, Rb, Cs, Cu, T1, H3O; B1 is one or more of Pb, Si, Ge, Sn, Mg, Ca, Sr, Ba, Zn, Cd, Hg; X1 is one or more of F, Cl, Br, I, BF4, HCOO, OH, CN, SCN, NCS, SH, NO3, H2POO; The two-dimensional perovskite is T1PbI3 or A23B22X29, where A2 is one or both of Cs and Rb; B2 is one or both of Sb and Bi; and X2 is one or more of F, Cl, Br, and I. Zero-dimensional perovskites are Cs3Bi2I9, Cs2TeI6, Cs2TeBr6 or Cs2TeCl6; Antiperovskite is Hg3Se2Br2 or T1Sn2I5.

4. The gamma-ray imaging device based on a perovskite semiconductor detector according to claim 1, characterized in that: The perovskite semiconductor detector is a planar array pixel detector with a square, circular or hexagonal pixel shape and a pixel size of 0.01 mm to 100 mm; or the perovskite semiconductor detector is a strip-shaped one-dimensional array detector with a strip size of 0.01 mm to 100 mm; The thickness of the perovskite semiconductor detector is 0.5mm~50mm.

5. The gamma-ray imaging device based on a perovskite semiconductor detector according to claim 1, characterized in that: Also includes: The second detector array is arranged on the side of the first detector array away from the collimator array, and includes multiple perovskite semiconductor detectors. It is used to detect gamma rays emitted from different positions of the object to be detected using multiple perovskite semiconductor detectors, and output multiple multi-channel sensing signals so that the multi-channel front-end readout module, the data acquisition and processing module and the host computer can obtain a distribution image of the radioactive elements in the object to be detected based on the multi-channel sensing signals output by the first detector array and the second detector array.

6. The gamma-ray imaging device based on a perovskite semiconductor detector according to claim 1, characterized in that: The collimator is a pinhole collimator, a parallel hole collimator, a diverging collimator or a converging collimator.

7. The gamma-ray imaging device based on a perovskite semiconductor detector according to claim 1, characterized in that: The host computer is connected to the collimator array and the first detector array, and is used to control the collimator array and the first detector array to rotate around the object to be detected, so as to collect gamma rays emitted from multiple projection angles of the object to be detected.

8. The gamma-ray imaging device based on a perovskite semiconductor detector according to claim 1, characterized in that: The data acquisition and processing modules include: an analog-to-digital converter, connected to the multi-channel front-end readout module, for converting the plurality of first signals and the plurality of second signals into a plurality of first digital signals and a plurality of second digital signals; The FPGA is communicatively connected to the analog-to-digital converter and the host computer, and is used to receive multiple first digital signals and multiple second digital signals after analog-to-digital conversion, and based on the control signal of the host computer, use an energy attenuation correction algorithm to correct each first digital signal, and use a depth correction algorithm based on the second digital signal and the internal weight potential distribution model of the perovskite semiconductor detector to further correct each first digital signal to compensate for the signal amplitude loss caused by the weight potential loss of the internal structure of the perovskite semiconductor detector; and transmit the multiple corrected first digital signals and multiple second digital signals to the host computer.

9. The gamma-ray imaging device based on a perovskite semiconductor detector according to claim 1, characterized in that: The host computer specifically includes: The image reconstruction module is used to receive each corrected first digital signal and each second digital signal, and use a filtered back projection algorithm and an iterative reconstruction algorithm to perform three-dimensional image reconstruction on the received multiple signals to obtain the distribution of radioactive elements in the object to be detected.

10. A gamma-ray imaging method based on a perovskite semiconductor detector, characterized in that: The method is implemented using the gamma-ray imaging device based on the perovskite semiconductor detector according to any one of claims 1 to 9, comprising: The gamma rays emitted from different positions of the object to be detected are collimated by using the collimators in the collimator array; Multiple perovskite semiconductor detectors are used to detect gamma rays emitted from different positions of the object to be detected, and multiple multi-channel sensing signals are output; Extracting a plurality of first signals containing incident energy information and a plurality of second signals related to incident event time information from a plurality of multi-channel sensing signals using a signal readout circuit of a plurality of channels in a multi-channel front-end readout module; Performing analog-to-digital conversion on the plurality of first signals and the plurality of second signals using a data acquisition and processing module to obtain a plurality of first digital signals and a plurality of second digital signals; and correcting the plurality of first digital signals to obtain a plurality of corrected first digital signals; An upper computer is used to perform image reconstruction based on each corrected first digital signal and each second digital signal to obtain a distribution image of the radioactive element in the object to be detected.

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