A detection imaging method and device for accurately obtaining gamma photon depth

Abstract

The application provides a detection imaging method and device for accurately obtaining the depth of a gamma photon, and relates to the field of radiation detection. The method comprises the following steps: after a gamma ray is incident on a segmented scintillation crystal strip, the signal intensity at both ends of the segmented scintillation crystal strip is obtained by using a double-end readout technology, and a DOI factor is calculated based on the difference between the signal intensities at both ends; the adjacent multiple crystal segments in the scintillation crystal strip are designed as scintillation crystal types with different decay time constants; a waveform discrimination technology is introduced, and a PSD factor is calculated according to the output waveform difference of different decay time crystals; a two-dimensional statistical chart is constructed according to the DOI factor and the PSD factor, gamma events are classified and distinguished through different regions in the two-dimensional statistical chart, the crystal segment where the gamma event occurs is determined, and then the depth position is obtained. The application combines the double-end readout technology and the waveform discrimination technology, and can further improve the DOI resolution limit of the scintillation crystal detector by comparing the signal difference at both ends and combining the signal waveform characteristics.

Description

Technical Field

[0001] This application relates to the field of radiation detection, and in particular to a detection imaging method and apparatus for accurately acquiring the depth of gamma photons. Background Technology

[0002] In scintillation crystal detectors with three-dimensional positioning capabilities, improving the detection accuracy of depth of photon interaction (DOI) has been a research hotspot, especially in the design of gamma locators, Compton cameras, small animal PET, and organ-level PET systems, where there is an urgent need to improve their spatial resolution. Currently, scintillation crystals can achieve planar positioning capabilities of 0.35 mm, but in the depth direction, there is still a lack of a practical way to improve the resolution to the sub-millimeter level.

[0003] Currently, there are two main methods for scintillator detectors to acquire DOI.

[0004] The first approach is spatial: by using spectral design, the distribution of scintillation photons detected in events at different DOIs is controlled to be different, and the DOI is determined by identifying the differences in this light distribution.

[0005] The second approach is time-based: multiple crystals are stacked to form a detector. Different types of scintillation crystals have different emission time decay constants, corresponding to different pulse waveforms in the detected signals. Pulse shape discrimination (PSD) is used to determine which crystal the event occurred in, thus determining the DOI. This method can currently distinguish between three types of crystals.

[0006] However, all current methods extract DOI information from parameters in one dimension, making it difficult to achieve sub-millimeter DOI resolution. The current schemes that can achieve sub-millimeter DOI resolution require at least three times more SiPMs compared to other schemes, which greatly increases the scale of signal processing and also limits the spatial arrangement of detectors. Summary of the Invention

[0007] This application aims to address the current difficulty in achieving sub-millimeter resolution in radiation detection devices, and at least to some extent solves one of the technical problems in related technologies.

[0008] Therefore, the first objective of this application is to propose a detection imaging method for accurately acquiring the depth of gamma photons.

[0009] The second objective of this application is to propose a detection and imaging device for accurately acquiring the depth of gamma photons.

[0010] The third objective of this application is to propose an electronic device.

[0011] The fourth objective of this application is to provide a computer-readable storage medium.

[0012] The fifth objective of this application is to provide a computer program product.

[0013] To achieve the above objectives, the first aspect of this application proposes a detection imaging method for accurately acquiring the depth of gamma photons, comprising:

[0014] After gamma rays are incident on the segmented scintillation crystal strip, the signal intensity at both ends of the segmented scintillation crystal strip is obtained using a dual-end readout technique, and the DOI factor is calculated based on the difference in signal intensity at both ends. The multiple adjacent crystal segments within the scintillation crystal strip are designed to be scintillation crystal types with different decay time constants.

[0015] A waveform discrimination technique is introduced to calculate the PSD factor based on the differences in the output waveforms of crystals with different decay times.

[0016] A two-dimensional statistical graph is constructed based on the DOI factor and the PSD factor. Gamma events are classified and identified by different regions within the two-dimensional statistical graph to determine the crystal segment in which the gamma event occurs, and then the depth location is obtained.

[0017] Optionally, the step of acquiring the signal intensity at both ends of the segmented scintillation crystal strip using dual-end readout technology and calculating the DOI factor based on the difference in signal intensity at both ends includes:

[0018] The signal intensities of the SiPMs at both ends of the segmented scintillation crystal strip are obtained using a dual-end readout technique and denoted as S1 and S2, respectively. The formula for calculating the signal intensity S of one end of the SiPM is as follows:

[0019] S=∫Wdt

[0020] Wherein, W is the waveform obtained by amplifying the signal generated by a certain SiPM;

[0021] The DOI factor is calculated based on the difference between the signal strengths S1 and S2 at both ends, using the following formula:

[0022]

[0023] Wherein, DOI is the DOI factor.

[0024] Optionally, the introduced waveform discrimination technology calculates the PSD factor based on the differences in the output waveforms of crystals with different decay times, including:

[0025] The PSD factor is calculated based on the characteristics of the waveform after summing the two ends.

[0026] Optionally, the step of calculating the PSD factor based on the characteristics of the waveform after summing the two ends includes:

[0027] The PSD factor is calculated by dividing the sum of the signal strengths at both ends by the maximum value obtained by summing the signals at both ends.

[0028] Alternatively, the PSD factor can be calculated by dividing the integral value of a portion of the waveform by the integral value of the entire waveform.

[0029] Optionally, the calculation of the PSD factor by dividing the sum of the signal strengths at both ends by the maximum value of the sum of the signals at both ends includes:

[0030]

[0031] Where PSD is the PSD factor, and W1 and W2 are the signals of SiPM at their respective ends.

[0032] To achieve the above objectives, a second aspect of this application provides a detection and imaging device for accurately acquiring the depth of gamma photons, comprising:

[0033] The first calculation module is used to obtain the signal intensity at both ends of the segmented scintillation crystal strip after gamma rays are incident on it, using a dual-end readout technique, and to calculate the DOI factor based on the difference in signal intensity at both ends. The multiple adjacent crystal segments within the scintillation crystal strip are designed to be scintillation crystal types with different decay time constants.

[0034] The second calculation module is used to introduce waveform discrimination technology and calculate the PSD factor based on the differences in the output waveforms of crystals with different decay times.

[0035] The classification and discrimination module is used to construct a two-dimensional statistical map based on the DOI factor and the PSD factor, classify and discriminate gamma events through different regions within the two-dimensional statistical map, determine the crystal segment in which the gamma event occurs, and then obtain its depth location.

[0036] To achieve the above objectives, a third aspect of this application provides an electronic device, including: a processor, and a memory communicatively connected to the processor;

[0037] The memory stores computer-executed instructions;

[0038] The processor executes computer execution instructions stored in the memory to implement the method as described in any one of the first aspects above.

[0039] To achieve the above objectives, a fourth aspect of this application provides a computer-readable storage medium storing computer-executable instructions that, when executed by a processor, are used to implement the method as described in any one of the first aspects above.

[0040] To achieve the above objectives, a fifth aspect of this application provides a computer program product including a computer program that, when executed by a processor, implements the method as described in any one of the first aspects above.

[0041] The technical solutions provided by the embodiments of this application bring at least the following beneficial effects:

[0042] Compared to other methods for estimating DOI information within scintillation crystals, the main advantage of this application lies in the introduction of new estimation parameters. Unlike other methods that obtain DOI information through a single approach, this application combines information from both intensity and temporal distribution dimensions to jointly estimate the DOI information, thereby further improving the limiting DOI resolution of scintillation crystal detectors. Verification experiments show that the combined gamma photon depth position estimation method with dual-end readout and waveform discrimination can achieve sub-millimeter DOI resolution, and the array constructed using this method can also achieve sub-millimeter three-dimensional position resolution.

[0043] Compared to previously published pixelated detector structures with single-end or double-end readout, this application further improves the DOI resolution, enabling the scintillator to achieve three-dimensional sub-millimeter resolution.

[0044] Compared with the proposed six-sided readout structure, this application can reduce the number of electronic readout channels by at least three times while achieving similar DOI resolution, thus making it easier to save costs and reduce data volume.

[0045] In addition, this application performs three-dimensional pixelation processing on the crystal array, which simplifies the detector calibration process.

[0046] Meanwhile, this application offers a high degree of freedom in crystal type selection and crystal segment design, allowing for flexible design based on actual needs.

[0047] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0048] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0049] Figure 1A schematic flowchart illustrating a detection imaging method for accurately acquiring the depth of gamma photons provided in an embodiment of this application;

[0050] Figure 2 A statistical chart of DOI factors obtained when the side of a crystal strip is irradiated with a radiation source using a radiation source, provided for an embodiment of this application;

[0051] Figure 3 This is a schematic diagram of a cyclic arrangement structure of segmented crystals composed of multiple decay time crystals, provided in an embodiment of this application.

[0052] Figure 4 This is a schematic diagram of the design of a scintillation crystal strip composed of crystals with different decay time constants, provided in an embodiment of this application.

[0053] Figure 5 The diagram shows the waveforms of signals generated by crystals with different decay time constants according to embodiments of this application.

[0054] Figure 6 This is a schematic diagram of the PSD-DOI provided for an embodiment of this application;

[0055] Figure 7 A physical schematic diagram of a 12×12 crystal array based on multiple crystal strips provided in an embodiment of this application;

[0056] Figure 8 The embodiments provided in this application are for the purpose of providing the following: Figure 7 The diagram shows a PSD-DOI of all events obtained from testing the crystal array shown.

[0057] Figure 9 The location statistics diagram provided in this application is plotted based on events in each crystal layer.

[0058] Figure 10 This is a schematic diagram of a detection and imaging device for accurately acquiring the depth of gamma photons, provided as an embodiment of this application. Detailed Implementation

[0059] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0060] Currently, there are two main methods for scintillator detectors to acquire DOI.

[0061] The first approach is spatial: through spectroscopic design, the distribution of scintillation photons detected at different DOIs is controlled to differ, and the DOI is determined by identifying these differences in light distribution. The specific method for this approach is as follows:

[0062] (1) A single crystal is coupled to a silicon photomultiplier (SiPM) array at one end. The distribution of photons at different three-dimensional detection positions in the crystal is different on the SiPM array, resulting in different signal distributions. This method can achieve a DOI resolution of about 3 mm for crystals with a thickness of not less than 15 mm.

[0063] (2) A crystal module composed of multiple crystal wafers is coupled to a SiPM array at one end. At this time, the DOI on each crystal wafer is determined by the broadening of the photon distribution in the continuous direction of the crystal. This method can currently achieve a DOI resolution of about 1.5 mm for a 1 mm × 37.6 mm × 20 mm thick crystal.

[0064] (3) A two-dimensional crystal array composed of slender crystal strips is coupled at one end to a SiPM array, and light sharing is performed in the crystal pixels (such as special reflective film design and the addition of light transmission channels at the top), so that the local light distribution is sensitive to changes in DOI. This method can achieve a resolution of 2.52mm for a 20mm thick crystal.

[0065] (4) The crystal array, composed of crystal strips, is coupled to a SiPM array at both ends. The DOI information is determined by comparing the signal differences at both ends. This method can achieve a DOI resolution of 1.67 mm for a crystal unit of 1 mm × 1 mm × 20 mm.

[0066] (5) A three-dimensional crystal array composed of crystal cubes is read out from all six sides, and the event is determined in which crystal cube it occurred by analyzing the signal distribution on the six sides. This method can currently achieve a DOI resolution of 0.77 mm for a crystal module of 13.1×13.1mm×13.1mm.

[0067] The second approach is time-based: multiple crystals are stacked to form a detector. Different types of scintillation crystals have different emission time decay constants, corresponding to different pulse waveforms in the detected signals. Pulse shape discrimination (PSD) is used to determine which crystal the event occurred in, thus determining the DOI. This method can currently distinguish between three types of crystals.

[0068] To address the current challenge of achieving sub-millimeter resolution in DOI (Depth of Indication) assessments, this application provides a detection imaging method for accurately acquiring gamma photon depth. By comparing signal differences at both ends and combining signal waveform characteristics, this method achieves higher DOI resolution compared to current single-method DOI acquisition. Furthermore, detectors designed based on this novel DOI estimation method can be applied to the design of systems such as gamma locators, Compton cameras, small animal PET, and organ-level PET systems, improving their spatial resolution performance.

[0069] Figure 1 This is a schematic flowchart illustrating a detection imaging method for accurately acquiring gamma photon depth, provided in an embodiment of this application. Figure 1 As shown, the method includes the following steps:

[0070] Step 101: After gamma rays are incident on the segmented scintillation crystal strip, the signal intensity at both ends of the segmented scintillation crystal strip is obtained using a dual-end readout technique, and the DOI factor is calculated based on the difference in signal intensity at both ends. The multiple adjacent crystal segments within the scintillation crystal strip are designed to be scintillation crystal types with different decay time constants.

[0071] Existing two-end readout methods, for segmented scintillation crystal bars, can limit the event location to a local region within the crystal bar if the specific crystal segment where the gamma event occurred can be identified. Therefore, the minimum distinguishable crystal segment length determines the DOI resolution of the segmented crystal bar. Typically, two-end readout estimation of DOI calculates a parameter value, defined as the DOI factor in this embodiment, to reflect the actual event location.

[0072] In this embodiment, the signal intensities of the SiPMs at both ends of the segmented scintillation crystal strip are first obtained using a dual-end readout technique, denoted as S1 and S2 respectively. The dual-end readout technique involves arranging SiPMs (silicon photomultiplier devices) at both ends of the crystal strip to read the scintillation light signal caused by incident gamma rays. The formula for calculating the signal intensity S of each SiPM is:

[0073] S=∫Wdt

[0074] Wherein, W is the waveform obtained by amplifying the signal generated by a SiPM at one end. In the embodiments of this application, the waveform signal is a scintillation light signal generated by the interaction between photons in the scintillation crystal strip and the crystal, which is detected by the SiPM array and converted into an electronic signal.

[0075] Next, this application calculates the DOI factor based on the difference between the signal strengths S1 and S2 at both ends. The formula for calculating the DOI factor is as follows:

[0076]

[0077] Wherein, DOI is the DOI factor.

[0078] It should be noted that because there is an interface with discontinuous optical properties between the crystal segments of a segmented crystal, the DOI factor values ​​within each crystal segment are relatively similar, while the DOI factors between crystal segments differ due to the presence of the interface. The conventional calibration method involves irradiating the side of the crystal strip with a radiation source, resulting in a statistical graph of the DOI factors, as shown below. Figure 2 As shown, this can be viewed as a superposition of the event distributions of each crystal segment. When the number of crystal segments is small, the responses of adjacent crystal segments are far apart, and the DOI factor curve shows a clear peak structure corresponding to each crystal segment. Increasing the number of crystal segments makes the responses of adjacent crystal segments closer and closer until the two peaks superimpose and become indistinguishable. At this point, this detector structure reaches the DOI resolution limit. Currently, the DOI resolution limit of segmented crystal dual-end readout for a 1mm×1mm×20mm crystal strip is 1.67mm.

[0079] To address the problem of indistinguishable adjacent crystal segments, this application introduces waveform discrimination technology (PSD) to differentiate adjacent crystal segments. Multiple adjacent crystal segments within a scintillation crystal strip are designed as scintillation crystal types with different decay time constants. The details will be explained in step 102.

[0080] Step 102: Introduce waveform discrimination technology and calculate the PSD factor based on the differences in the output waveforms of crystals with different decay times.

[0081] As described in step 101, to address the problem of indistinguishable adjacent crystal segments, this application introduces waveform discrimination (PSD) technology to differentiate them. Specifically, the crystal segments within the scintillation crystal strip are distinguished by being designed as scintillation crystal types with different decay time constants, and these crystal segments are arranged in a specific structure within the crystal strip. In one embodiment of this application, three adjacent crystal segments within the crystal strip are designed as scintillation crystal types with different decay time constants, and these crystal segments exhibit a structure of three crystals arranged in a cyclic arrangement, such as... Figure 3 As shown.

[0082] The advantage of this design lies in the fact that the difference in decay time constants between different crystal segments allows the photon output waveform of each segment to exhibit distinct characteristics, thus enabling more accurate estimation of the event's location. Especially when high DOI resolution is required, using crystal types with different decay time constants effectively avoids cross-interference between the responses of adjacent crystal segments, thereby improving the accuracy of DOI estimation.

[0083] In this structure, the parameters for estimating the DOI location increase to two: one is the DOI factor, which is the signal strength difference obtained through dual-end readout technology, and the other is the difference in the output waveform of crystals with different decay times, the latter being characterized by the waveform discrimination parameter (PSD factor). The core purpose of introducing the PSD factor is to further improve the DOI positioning accuracy at high resolution, especially when the signal characteristics of adjacent crystal segments are similar. The PSD factor can effectively distinguish adjacent crystal segments, avoiding the resolution degradation caused by signal overlap in traditional methods.

[0084] In this embodiment, the PSD factor is obtained by analyzing the signal waveform amplified by the SiPM. There are two methods for its calculation:

[0085] The first calculation method calculates the PSD factor by dividing the sum of the signal strengths at both ends by the maximum value obtained by summing the signals at both ends. The advantage of this method is that it can make full use of the differences in the signal waveforms at both ends, and it is suitable for distinguishing different types of crystals.

[0086] The second calculation method calculates the PSD factor by dividing the integral value of the waveform signal at both ends by the integral value of the entire waveform. This method focuses more on the changes in the overall signal and is relatively suitable for analyzing the global characteristics of the waveform.

[0087] In one embodiment of this application, the PSD factor is calculated using a first method, as shown in the following formula:

[0088]

[0089] Where PSD is the PSD factor, and W1 and W2 are the signals of SiPM at their respective ends.

[0090] It's understandable that by introducing the PSD factor, the DOI location of an event can be estimated by combining the PSD factor and the DOI factor. Specifically, the PSD factor is mainly used to distinguish adjacent crystal segments, effectively differentiating segments with different decay time constants based on waveform characteristics, while the DOI factor is used to determine the depth location of the event. The combined use of both effectively avoids interference between adjacent crystal segments when DOI resolution is high, thus improving the system's positioning accuracy.

[0091] For example, although crystal segments with different decay times may overlap in signal intensity, their waveform differences allow for effective differentiation of these overlapping signals using the PSD factor, thus accurately locating the event. Compared to traditional methods, the joint estimation approach proposed in this application significantly improves DOI resolution, especially in high-resolution detector structures, achieving sub-millimeter accuracy.

[0092] Step 103: Construct a two-dimensional statistical graph based on the DOI factor and the PSD factor, classify and distinguish gamma events through different regions within the two-dimensional statistical graph, determine the crystal segment in which the gamma event occurs, and then obtain its depth location.

[0093] To further improve the accuracy of DOI estimation, this application constructs a two-dimensional statistical graph (PSD-DOI graph) by combining the DOI factor and the PSD factor. This graph utilizes the spatial and temporal variation characteristics of the DOI and PSD factors. The distribution of these two factors on a two-dimensional plane visually reflects the distribution patterns of different gamma events, thereby enabling accurate classification of gamma events.

[0094] Specifically, the two-dimensional statistical graph (PSD-DOI graph) uses the DOI factor and PSD factor as coordinate axes to form a two-dimensional coordinate system. In this graph, different regions represent different crystal segments and their depth locations. By analyzing this graph, gamma events can be classified and identified in different regions, thereby determining the specific crystal segment and its depth location where the gamma event occurred.

[0095] By introducing a two-dimensional statistical graph, this application can achieve accurate classification of gamma events while maintaining DOI resolution. This method fully utilizes the multidimensional information provided by the DOI factor and PSD factor, overcoming the limitations of traditional methods that rely on a single parameter for localization. By analyzing different regions in the PSD-DOI graph, adjacent crystal segments can be effectively distinguished, and accurate judgments can be made at different depths within the same crystal segment.

[0096] The advantage of this method is that it provides an intuitive and easy-to-understand way to process complex signal information in scintillation crystal detectors. By classifying and distinguishing different regions, the performance of the detector in complex environments can be significantly improved, resulting in more accurate estimation of the depth position of gamma photons.

[0097] By combining the DOI factor and PSD factor, this application significantly improves the limiting DOI resolution of scintillation crystal detectors. Adjacent crystal units are primarily distinguished by the PSD factor, while crystal segments of the same type that are far apart are distinguished by the DOI factor. This design effectively enhances the detector's resolution under complex conditions, especially in applications requiring extremely high spatial resolution. The method in this application has high adaptability and flexibility and can be widely applied to detectors requiring high-precision gamma photon positioning, such as PET scanners and gamma cameras.

[0098] Furthermore, the scintillator detector design based on this application has many selectable and scenario-optimized components:

[0099] (1) Selection of crystal type. When designing a scintillator detector, it is very important to select different types of scintillation crystals. In the embodiments of this application, the attenuation constants of different types of crystals need to be different, and the maximum attenuation time constant cannot be too long, otherwise it will affect the limiting count rate of the detector.

[0100] It should be noted that the types of crystals selected are not limited to the three types shown in the above embodiments. Any crystal with two or more different decay times is applicable to this application.

[0101] (2) Crystal sorting. The crystal sorting does not need to be strictly in a cyclical order, but can be optimized according to performance preferences. In specific applications, especially detectors operating under high count rate conditions, the crystal sorting can be customized according to the regional performance requirements. For example, crystals with shorter decay times can be selected near the imaging region, which can effectively reduce dead time during the detection process, ensuring efficient detection while improving the real-time response capability of the signal.

[0102] (3) Selection of Crystal Size. Since the detector structure designed in this application can achieve high resolution for small-sized crystal segments, it is compatible with scintillation crystals of various sizes. The number of crystal segments and the three-dimensional dimensions of a single crystal segment can be adjusted according to design requirements. This flexibility allows the detector to adapt to different working scenarios and target needs. Furthermore, this design method also supports the combination of crystal segments of different lengths, enabling the detector to be customized more individually and flexibly to meet diverse application requirements.

[0103] (4) Selection of Crystal Surface Treatment. The surface treatment process of the crystal segment has a significant impact on the transmission characteristics of scintillation light, which in turn affects the resolution performance of the crystal segment on the PSD-DOI map. The surface treatment method also affects the light output at different locations in the detector, thus affecting the energy resolution of each crystal segment. Common surface treatment processes include polishing and rough grinding, with rough grinding allowing for adjustment of surface roughness based on particle size. Selecting an appropriate surface treatment process can improve the detector's detection efficiency and ensure that the detector performs optimally in different application scenarios.

[0104] (5) Reflective film surrounding the crystal. To reduce scintillation light leakage, a reflective film is usually added to the outside of the crystal strip. Reflective materials are mainly divided into two categories: specular reflection and diffuse reflection. Specular reflection films (such as ESR films) can achieve efficient light reflection and are suitable for applications requiring concentrated reflected light; diffuse reflection materials (such as MgO, Al2O3, BaSO4 powders, or Teflon films) are suitable for diffused reflected light and can provide better performance in situations requiring more uniform light distribution. By selecting a suitable reflective film, the utilization rate of scintillation light can be effectively improved, light loss reduced, and the overall performance of the detector optimized.

[0105] Based on the above design method, this application also designs a scintillation crystal strip and evaluates its performance through experiments. Specifically, the crystal strip uses three types of cerium-doped gadolinium gallium aluminum garnet (GAGG:Ce) crystals with different decay time constants. The three GAGG:Ce crystals have the same density and reflectivity, and their decay times, from shortest to longest, are approximately 50 ns, approximately 140 ns, and approximately 200 ns, respectively denoted as GAGG-50, GAGG-140, and GAGG-200. The crystal strip consists of 25 cubic crystal segments, each 0.8 mm in size. All segments are bonded together with optical adhesive to form a 0.8 mm × 0.8 mm × 20 mm crystal strip. The outer ends of the crystal strip are wrapped with reflective material, and SiPMs are coupled at both ends for double-ended readout. The design diagram is shown below. Figure 4 As shown.

[0106] The waveforms of the signals generated by GAGG-50, GAGG-140, and GAGG-200 are as follows: Figure 5 As shown, the difference in waveform shape can be clearly observed.

[0107] Furthermore, all crystal segments of the crystal strip were numbered #1, #2, ..., #25 from left to right. The sides of the crystal were irradiated with a 22Na exemption source (primary gamma ray energy of 511 keV, the same as the nuclide energy used in positron emission tomography in nuclear medicine). Sufficient event data were collected using a data acquisition system to obtain the final PSD-DOI. Figure 6 As shown, all numbered crystal segments can be clearly distinguished in the PSD-DOI image, and crystal segments with the same decay time constant are all in the same row. This result proves that the combined gamma photon depth position estimation method of dual-end readout and waveform discrimination can achieve a DOI resolution of 0.8 mm in actual single crystal strip testing.

[0108] It should be noted that this application is not limited to the design of single crystals. By constructing a two-dimensional array of multiple crystal strips, this method can provide high-precision three-dimensional positioning capabilities. In one embodiment, this application also designs a 12×12 crystal array based on the aforementioned crystal strips, as shown in the physical diagram below. Figure 7 As shown.

[0109] Using the same experimental conditions Figure 7 The crystal array shown was tested to obtain the PSD-DOI for all events. Figure 8 As shown.

[0110] It can be seen that the responses of all 25 crystal layers can be clearly distinguished. The events of each crystal layer are selected and their position statistics are plotted as shown in Figure 9. The 12×12 crystal segments of all crystal layers can be distinguished on the position statistics plot. The detector designed according to this method can achieve a three-dimensional position resolution of 0.8 mm.

[0111] In addition, this application can also be applied to the design of other scintillator detectors that require high DOI resolution, and can improve the DOI limit resolution of the detector over a wide energy range.

[0112] To achieve the above embodiments, this application also proposes a detection imaging device for accurately acquiring the depth of gamma photons. Figure 10 This is a schematic diagram of a detection and imaging device for accurately acquiring the depth of gamma photons, provided as an embodiment of this application. Figure 10 As shown, the device includes:

[0113] The first calculation module is used to obtain the signal intensity at both ends of the segmented scintillation crystal strip after gamma rays are incident on it, using a dual-end readout technique, and to calculate the DOI factor based on the difference in signal intensity at both ends. The multiple adjacent crystal segments within the scintillation crystal strip are designed to be scintillation crystal types with different decay time constants.

[0114] The second calculation module is used to introduce waveform discrimination technology and calculate the PSD factor based on the differences in the output waveforms of crystals with different decay times.

[0115] The classification and discrimination module is used to construct a two-dimensional statistical map based on the DOI factor and the PSD factor, classify and discriminate gamma events through different regions within the two-dimensional statistical map, determine the crystal segment in which the gamma event occurs, and then obtain its depth location.

[0116] To implement the above embodiments, this application also proposes an electronic device, including: a processor and a memory communicatively connected to the processor; the memory stores computer execution instructions; the processor executes the computer execution instructions stored in the memory to implement the method provided in the foregoing embodiments.

[0117] To implement the above embodiments, this application also proposes a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the methods provided in the foregoing embodiments.

[0118] To implement the above embodiments, this application also proposes a computer program product, including a computer program that, when executed by a processor, implements the methods provided in the foregoing embodiments.

[0119] The collection, storage, use, processing, transmission, provision, and disclosure of user personal information involved in this application all comply with the provisions of relevant laws and regulations and do not violate public order and good morals.

[0120] It should be noted that personal information collected from users should be used for legitimate and reasonable purposes and should not be shared or sold outside of these legitimate uses. Furthermore, such collection / sharing should only be conducted after receiving the user's informed consent, including but not limited to notifying the user to read the user agreement / user notice and sign an agreement / authorization that includes authorization of relevant user information before the user uses the function. In addition, any necessary steps must be taken to protect and safeguard access to such personal information data and ensure that others with access to personal information data comply with their privacy policies and procedures.

[0121] This application is intended to provide an implementation scheme for users to selectively prevent the use or access to their personal information data. Specifically, this disclosure is intended to provide hardware and / or software to prevent or block access to such personal information data. Once personal information data is no longer needed, risks can be minimized by restricting data collection and deleting data. Furthermore, where applicable, such personal information is de-identified to protect user privacy.

[0122] In the foregoing descriptions of the embodiments, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0123] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0124] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0125] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0126] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0127] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0128] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0129] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

[0130] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this application can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this application can be achieved, and this is not limited herein.

[0131] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A detection imaging method for accurately acquiring the depth of gamma photons, characterized in that, Includes the following steps: After gamma rays are incident on the segmented scintillation crystal strip, the signal intensity at both ends of the segmented scintillation crystal strip is obtained using a dual-end readout technique, and the DOI factor is calculated based on the difference in signal intensity at both ends. The multiple adjacent crystal segments within the scintillation crystal strip are designed to be scintillation crystal types with different decay time constants. A waveform discrimination technique is introduced to calculate the PSD factor based on the differences in the output waveforms of crystals with different decay time constants; A two-dimensional statistical map is constructed based on the DOI factor and the PSD factor. Gamma events are classified and identified by different regions within the two-dimensional statistical map to determine the crystal segment in which the gamma event occurs, and then its depth location is obtained. The step of acquiring the signal intensity at both ends of the segmented scintillation crystal strip using dual-end readout technology and calculating the DOI factor based on the difference in signal intensity at both ends includes: The signal intensities of the SiPM at both ends of the segmented scintillation crystal strip were obtained using a dual-end readout technique and denoted as follows: and ; where the signal strength of a certain SiPM end The calculation formula is: in, The waveform obtained by amplifying the signal generated by a SiPM at one end; Based on signal strength at both ends and The difference is used to calculate the DOI factor, using the following formula: in, DOI factor; The introduced waveform discrimination technology calculates the PSD factor based on the differences in the output waveforms of crystals with different decay time constants, including: By using different types of scintillation crystals with varying decay time constants, multiple crystal segment structures are formed within the segmented scintillation crystal strip, generating signal waveforms at both ends; The PSD factor is calculated based on the characteristics of the waveform after summing the two ends. The PSD factor is calculated based on the characteristics of the waveform after summing the two ends, including: The PSD factor is calculated by dividing the sum of the signal strengths at both ends by the maximum value obtained by summing the signals at both ends. Alternatively, the PSD factor can be calculated by dividing the integral value of a portion of the waveform by the integral value of the entire waveform. The PSD factor is calculated by dividing the sum of the signal strengths at both ends by the maximum value obtained by summing the signals at both ends, including: in, For PSD factor, and The signals at both ends of the SiPM are respectively.

2. A detection and imaging device for accurately acquiring gamma photon depth based on the method of claim 1, characterized in that, include: The first calculation module is used to obtain the signal intensity at both ends of the segmented scintillation crystal strip after gamma rays are incident on it, using a dual-end readout technique, and to calculate the DOI factor based on the difference in signal intensity at both ends. The multiple adjacent crystal segments within the scintillation crystal strip are designed to be scintillation crystal types with different decay time constants. The second calculation module is used to introduce waveform discrimination technology and calculate the PSD factor based on the differences in the output waveforms of crystals with different decay time constants. The classification and discrimination module is used to construct a two-dimensional statistical map based on the DOI factor and the PSD factor, classify and discriminate gamma events through different regions within the two-dimensional statistical map, determine the crystal segment in which the gamma event occurs, and then obtain its depth location.

3. An electronic device, characterized in that, include: A processor, and a memory communicatively connected to the processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory to implement the method as described in claim 1.

4. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the method as described in claim 1.

5. A computer program product, characterized in that, Includes a computer program that, when executed by a processor, implements the method of claim 1.

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