Radiation imaging method based on ray camera and ray camera

Abstract

The embodiment of the invention provides a radiation imaging method based on a ray camera and the ray camera, and is applied to the technical field of radiation detection. The ray camera comprises a composite coding collimator and a detector, the composite coding collimator comprises a front-side coding plate and a peripheral coding plate, and the front-side coding plate and the peripheral coding plate are different in collection view field. The radiation signals are received by using the collection view fields corresponding to the front-side coding plate and the peripheral coding plate, and coding projection images corresponding to the radiation signals are generated on the detector; and determining decoding information corresponding to the composite coding collimator, and performing decoding calculation on the coding projection image based on the decoding information to obtain a spatial distribution image corresponding to the radiation signal. Through the composite encoder, the collection view fields of the two encoding plates can be combined to receive radiation signals, so that the purpose of expanding the collection view fields is achieved, and the problems of low radiation detection efficiency and inaccuracy caused by a narrow view field are solved.

Description

Technical Field

[0001] The embodiments in this specification relate to the field of radiation detection technology, and in particular to a radiation imaging method and a ray camera based on a ray camera. Background Technology

[0002] In the field of nuclear safety monitoring and emergency response, radiation imaging technology is crucial for the rapid location and identification of radioactive sources. Currently, radiation imaging cameras based on the coded aperture principle are commonly used tools. However, existing equipment has significant limitations in practical applications. These cameras typically have a narrow field of view, leading to inefficiency in searching for radioactive sources in unknown environments and making it easy to miss targets. They cannot meet the on-site requirements for comprehensive and rapid assessment of complex radiation fields. Therefore, providing a solution to the problem of limited field of view in existing radiation imaging equipment is an urgent issue to be addressed in this field. Summary of the Invention

[0003] In view of this, embodiments of this specification provide a radiation imaging method based on a ray camera. One or more embodiments of this specification also relate to a ray camera, a radiation imaging device based on a ray camera, a computing device, a computer-readable storage medium, and a computer program product, to address the technical deficiencies existing in the prior art.

[0004] According to a first aspect of the embodiments of this specification, a radiation imaging method based on a ray camera is provided. The ray camera includes a composite coded collimator and a detector. The composite coded collimator includes a front coded plate and a perimeter coded plate, wherein the front coded plate and the perimeter coded plate have different fields of view. The method includes: The composite coding collimator receives radiation signals using the acquisition fields corresponding to the front coding plate and the four surrounding coding plates, and generates a coded projection image corresponding to the radiation signals on the detector. Determine the decoding information corresponding to the composite coded collimator, and perform decoding calculations on the coded projection image based on the decoding information to obtain the spatial distribution image corresponding to the radiation signal.

[0005] According to a second aspect of the embodiments of this specification, a ray camera is provided, the ray camera including an imaging unit, the imaging unit including a composite coding collimator and a detector, the composite coding collimator including a front coding plate and a four-sided coding plate, the front coding plate and the four-sided coding plate having different acquisition fields of view; The imaging unit is used to generate a spatial distribution image according to any of the above-mentioned radiation imaging methods based on a ray camera.

[0006] According to a third aspect of the embodiments of this specification, a radiation imaging device based on a ray camera is provided. The ray camera includes a composite coded collimator and a detector. The composite coded collimator includes a front coded plate and a surrounding coded plate, wherein the front coded plate and the surrounding coded plate have different fields of view. The method includes: The encoding module is configured to receive radiation signals through the composite encoding collimator using the acquisition fields of the front encoding plate and the four surrounding encoding plates respectively, and generate an encoded projection image corresponding to the radiation signals on the detector. The decoding module is configured to determine the decoding information corresponding to the composite coded collimator, and perform decoding calculations on the coded projection image based on the decoding information to obtain the spatial distribution image corresponding to the radiation signal.

[0007] According to a fourth aspect of the embodiments of this specification, a computing device is provided, comprising: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions, which, when executed by the processor, implement the steps of the radiation imaging method based on the X-ray camera described above.

[0008] According to a fifth aspect of the embodiments of this specification, a computer-readable storage medium is provided that stores computer-executable instructions, which, when executed by a processor, implement the steps of the radiation imaging method based on a ray camera described above.

[0009] According to a sixth aspect of the embodiments of this specification, a computer program product is provided, including a computer program or instructions that, when executed by a processor, implement the steps of the above-described radiation imaging method based on a X-ray camera.

[0010] One embodiment of this specification utilizes a composite coded collimator composed of a front coded plate and four coded plates with different acquisition fields of view. This allows the composite encoder to combine the acquisition fields of view of the two coded plates for receiving radiation signals, thereby expanding the acquisition field of view and solving the problem of low efficiency and inaccuracy in radiation detection caused by a narrow field of view. The signal received by the composite coded collimator generates a coded projection image with a large field of view mixing characteristics on the detector. Subsequently, the coded projection image is decoded and calculated using the decoded information to reconstruct the spatial distribution image of the radiation signal. This enables rapid and accurate acquisition of a panoramic image of the radiation field within an ultra-large field of view, improving radiation detection efficiency. Attached Figure Description

[0011] Figure 1 A flowchart of a radiation imaging method based on a ray camera according to one embodiment of this specification is shown; Figure 2A This is a schematic diagram of the appearance of a X-ray camera provided in one embodiment of this specification; Figure 2B This is an internal schematic diagram of a X-ray camera provided in one embodiment of this specification; Figure 3A This is a schematic diagram of the encoder board structure of a composite encoder collimator provided in one embodiment of this specification; Figure 3B This is a schematic diagram of a field of view provided in one embodiment of this specification; Figure 4A This is a schematic diagram of the center of the field of view provided in one embodiment of this specification; Figure 4B This is a schematic diagram of an image of the middle section of a field of view provided in one embodiment of this specification; Figure 4C This specification provides an embodiment of an image schematic diagram of the edge of a field of view; Figure 5A This is a schematic diagram of the structure of an imaging unit provided in one embodiment of this specification; Figure 5B This is a schematic diagram of the internal structure of an imaging unit provided in this specification; Figure 6 A schematic diagram of a radiation imaging device based on a ray camera, according to one embodiment of this specification, is shown. Figure 7 This specification shows a schematic diagram of the structure of a X-ray camera according to one embodiment; Figure 8 A structural block diagram of a computing device provided according to one embodiment of this specification is shown. Detailed Implementation

[0012] Many specific details are set forth in the following description to provide a full understanding of this specification. However, this specification can be implemented in many other ways than those described herein, and those skilled in the art can make similar extensions without departing from the spirit of this specification. Therefore, this specification is not limited to the specific implementations disclosed below.

[0013] The terminology used in one or more embodiments of this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the one or more embodiments of this specification. The singular forms “a,” “described,” and “the” as used in one or more embodiments of this specification and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in one or more embodiments of this specification refers to and includes any or all possible combinations of one or more associated listed items.

[0014] It should be understood that although the terms first, second, etc., may be used to describe various information in one or more embodiments of this specification, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, first may also be referred to as second without departing from the scope of one or more embodiments of this specification, and similarly, second may also be referred to as first. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to a determination."

[0015] Furthermore, it should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in one or more embodiments of this specification are all information and data authorized by the user or fully authorized by all parties. Moreover, the collection, use and processing of related data must comply with the relevant laws, regulations and standards of the relevant countries and regions, and corresponding operation entry points are provided for users to choose to authorize or refuse.

[0016] First, the terms and concepts used in one or more embodiments of this specification will be explained.

[0017] Gamma rays, thermal neutrons, and fast neutrons: Gamma rays are electromagnetic radiation (high-energy photons) with extremely short wavelengths and strong penetrating power. They are usually released when atomic nuclei transition from an excited state to the ground state, or are produced in conjunction with radioactive decay or nuclear reactions. They are one of the most frequently detected signals in radiation imaging. Thermal neutrons are neutrons that have reached thermal equilibrium with the surrounding medium (usually the medium at ambient temperature). Their energy distribution follows the Maxwell-Boltzmann distribution, with typical energies of approximately 0.025 eV (electronvolt). Fast neutrons are neutrons with higher energies, typically ranging from approximately 0.1 MeV (mega-electronvolt) to 20 MeV. Their energies are significantly higher than thermal neutrons, resulting in stronger penetrating power and different interaction mechanisms. The radiation signals detected in the embodiments of this specification may include gamma rays, thermal neutrons, and / or fast neutrons.

[0018] Field of View (FOV): The field of view refers to the spatial angular range within which a radiation imaging system can effectively image. In the embodiments described in this specification, the total field of view is composed of the central field of view determined by the front encoder plate and the extended field of view contributed by the surrounding encoder plates.

[0019] In fields such as nuclear safety monitoring, radioactive source location, nuclear emergency response, and nuclear facility decommissioning, it is crucial to rapidly and accurately obtain information on the spatial distribution and composition of radiation fields. Traditional radiation monitoring instruments (such as dose rate meters and inspection instruments) can only provide point count information and cannot achieve imaging, making it difficult to meet the needs for precise location and identification of radiation sources.

[0020] In recent years, radiation cameras based on coded aperture imaging technology have become a research and application hotspot. This technology uses a collimator with a specific aperture pattern (coded plate) placed in front of the detector to create a shadow map (i.e., coded projection) of the radiation source on the detector plane, which is related to its spatial distribution. A mathematical reconstruction algorithm then reconstructs the two-dimensional distribution image of the radiation source. Compared to traditional pinhole or parallel-aperture collimators, coded aperture technology has significant advantages in sensitivity and imaging efficiency. However, current mainstream coded aperture radiation imaging schemes face two prominent technical bottlenecks in practical applications: First, the imaging field of view is narrow. Existing equipment typically uses a single planar encoder structure located directly in front of the detector. Due to the geometric characteristics of this structure, the effective imaging field of view of the system is generally small (typically around 40°). When facing tasks involving searching for radiation sources in open areas, complex building structures, or unknown directions, the narrow field of view forces operators to perform time-consuming and systematic multi-angle scans, resulting in low survey efficiency and making it easy to miss radiation sources located to the side due to scanning blind spots. This makes it difficult to meet the urgent need for rapid and comprehensive monitoring in emergency response.

[0021] Second, their functionality is limited, making it impossible to simultaneously distinguish and image multiple types of radiation. Gamma rays and neutrons, especially thermal and fast neutrons, differ significantly in their physical properties, shielding requirements, and the types of nuclear materials they indicate. Most existing imaging devices are optimized for a single type of radiation: gamma cameras are typically insensitive to neutrons, while neutron cameras suffer severe performance degradation under strong gamma backgrounds and lack online discrimination capabilities for neutron energy. In real mixed radiation fields, this necessitates operators carrying multiple devices or performing numerous measurements, which is not only cumbersome and inefficient but also prevents obtaining synchronous distribution information of multiple types of radiation at the same time and in the same spatial coordinate system, severely hindering a comprehensive and rapid assessment of the radiation situation on-site.

[0022] In addition, some laboratory systems with certain imaging capabilities are often bulky, poorly integrated, rely on external power supplies and processing equipment, have poor portability, and are difficult to deploy flexibly in harsh environments such as accident sites and the field.

[0023] Therefore, in response to the two core problems of existing coded aperture radiation imaging devices—namely, low search efficiency due to limited field of view and inability to simultaneously image and distinguish multiple radiations due to limited functionality—developing a portable device capable of achieving wide field of view and simultaneous imaging of multiple radiations has become a critical technical challenge that urgently needs to be overcome to improve the practical capabilities of nuclear safety monitoring and emergency response.

[0024] This specification provides a radiation imaging method based on a ray camera. This specification also relates to a ray camera, a radiation imaging device based on a ray camera, a computing device, a computer-readable storage medium, and a computer program product, which will be described in detail in the following embodiments.

[0025] See Figure 1 , Figure 1 A flowchart of a radiation imaging method based on a ray camera according to an embodiment of this specification is shown. The ray camera includes a composite coded collimator and a detector. The composite coded collimator includes a front coded plate and a perimeter coded plate. The front coded plate and the perimeter coded plate have different acquisition fields of view. The method specifically includes the following steps.

[0026] Step 102: Using the composite coded collimator, the radiation signal is received by the acquisition field of view corresponding to the front coded plate and the four coded plates respectively, and the coded projection image corresponding to the radiation signal is generated on the detector.

[0027] In the field of radiation monitoring, particularly in emergency response and nuclear security scenarios requiring rapid location and identification of radioactive sources, two typical types of tools have limitations: one is portable radiation monitoring instruments (such as dose rate meters), which, while providing radiation intensity readings, cannot provide spatial location and distribution images of radiation sources, resulting in low location efficiency. The other is large, fixed or laboratory imaging systems, which may have imaging capabilities, but are often bulky, power-hungry, and complex to operate, making them unsuitable for rapid deployment at accident sites, in the field, or while mobile. To resolve the contradiction between "rapidly obtaining intuitive radiation distribution images" and "the equipment must be portable and deployable on-site," this manual provides a radiation imaging method based on a X-ray camera, integrating the imaging technology into a single, integrated device—the X-ray camera. The X-ray camera, like a regular optical camera, is designed to directly generate an image reflecting the spatial location and relative intensity of a radiation source through imaging, thus encapsulating professional radiation detection and imaging capabilities into a field tool that is easy for non-expert users to operate and intuitively understand.

[0028] The X-ray camera mentioned in this manual specifically refers to an integrated radiation imaging device. Here, "rays" primarily refers to gamma rays and neutrons (including thermal neutrons and fast neutrons) that the device can detect. The X-ray camera simulates the basic working logic of an optical camera, collecting signals from space through a composite coded collimator, recording them on a radiation detector with specific functions, and then reconstructing them into an image through an internal processor. Its core feature lies in the high integration of functional modules such as radiation signal acquisition, encoding, detection, data processing, and image generation into a portable and easy-to-operate housing, enabling on-site imaging capabilities.

[0029] In one specific embodiment, the X-ray camera can be designed as a device similar to a high-end digital camera or a handheld thermal imager, such as... Figure 2A As shown, Figure 2A This is a schematic diagram of the appearance of a X-ray camera provided in one embodiment of this specification. Figure 2A The X-ray camera in this unit comprises a robust, single-piece housing that integrates all core components. At the front is the light inlet for the composite coded collimator (covered by an opaque protective cover), and a visible light camera lens for positioning assistance. The body may include a handle, control buttons, and a display screen. See also Figure 2B , Figure 2B This is a schematic diagram of the internal structure of a X-ray camera provided in one embodiment of this specification. The X-ray camera's housing contains a chamber, which is divided into several functional areas, including an imaging unit, a processing and display unit, and auxiliary units. The imaging unit houses a composite coded collimator, a detector crystal (such as CLYC, a novel crystal material prepared from a mixture of cesium chloride (CsCl) and yttrium chloride (YCl3)), a photoelectric sensor (such as a SiPM, Silicon Photomultiplier), and front-end electronics, responsible for capturing and primary converting radiation signals. The processing and display unit houses an embedded computer (host computer) that runs image reconstruction, fusion, and display software; the screen displays real-time radiation distribution images or fused images. The auxiliary units include a battery module that powers the entire system, and a camera for acquiring the scene background.

[0030] In practice, the operator uses a handheld device to simultaneously collect radiation signals and visible light and infrared images. After the data collection is complete, the internal processor automatically performs event identification, image reconstruction and fusion, and finally displays a clear radiation hotspot distribution map overlaid on the scene map directly on the screen.

[0031] In summary, the integrated, portable design allows the equipment to be powered on, moved, and used for imaging at any time, eliminating reliance on fixed laboratory environments and external power supplies. This directly addresses the bottlenecks of slow deployment and inability to access complex environments for large equipment, meeting the stringent requirements for rapid response and flexible operation in scenarios such as nuclear emergency response and security patrols.

[0032] In practical applications, traditional coded aperture radiation cameras typically employ a single front-mounted planar coded plate structure. This structure has inherent physical limitations: its effective imaging field of view (FOV) is restricted by the geometric relationship between the coded plate and the detector, usually only reaching about 40°. This leads to repeated scanning rotations during the search for unknown radiation sources, resulting in low efficiency and a high risk of missing radiation sources located to the side. To fundamentally address the core problem of "low search efficiency due to narrow field of view," the embodiments in this specification abandon the single coded plate structure and propose a composite coded collimator composed of a front coded plate and four surrounding coded plates. The purpose of this design is to combine the traditional central field of view with the newly added lateral field of view through the synergistic spatial layout of the two coded plates, thereby achieving a significant expansion of the imaging field of view without sacrificing resolution, to meet the urgent need for rapid, large-scale radiation monitoring.

[0033] The composite coded collimator is a mechanical assembly integrating two parts. Its "composite" nature is mainly reflected in two aspects: first, structural composite, that is, it is composed of coded plates with different spatial orientations; second, functional composite, its materials must be able to effectively shield and encode different types of radiation such as gamma rays, thermal neutrons and fast neutrons, laying the hardware foundation for multi-radiation imaging.

[0034] The front encoder plate refers to the encoder plate located at the forefront of the composite encoder collimator, i.e., closest to the radiation source, in the imaging direction. Its plane is usually perpendicular or approximately perpendicular to the system's imaging optical axis, and it is mainly responsible for receiving and encoding radiation signals from the central region directly in front of the camera (e.g., within approximately ±20°). It is the main component for achieving high-resolution central imaging.

[0035] The four-sided encoder plate refers to the encoder plate connected to the edge of the front encoder plate and extending behind it in the direction of the detector, i.e., the imaging direction. They typically form a cylindrical or box-shaped sidewall around the front plate, with their normal direction making a large angle with the optical axis. They are mainly responsible for receiving and encoding radiation signals from a wide range of lateral angles (e.g., directions with angles of 20° to 50° with the optical axis), and their core function is to extend the total field of view of the system.

[0036] In practice, the acquisition fields of view of the front encoder board differ from those of the surrounding encoder boards, which is the fundamental functional difference between them. The acquisition field of view can be understood as the spatial angular range within which each encoder board can effectively receive radiated signals. The acquisition field of view (center field of view) of the front encoder board differs spatially from that of the surrounding encoder boards (extended field of view), and the latter effectively complements and extends the former. Together, they define a total imaging field of view that is much larger than that of traditional designs, and may be continuous or partially overlapping.

[0037] In a specific embodiment of this specification, the mechanical structure of the composite coded collimator can be designed as follows: The front coding plate is a flat, square coding plate using a modified uniform redundancy array as its coding pattern. This plate is mounted directly opposite the detector, determining the system's central field of view to be approximately 40°, or about 20° to the left and right of the optical axis. The surrounding coding plates consist of four independent trapezoidal or rectangular coding plates, one side of which is rigidly connected to the four sides of the front coding plate and extends rearward, forming a box structure with an opening at the rear. The surrounding coding plates employ a simplified multi-hole coding pattern, for example, only five regularly arranged circular holes on each side plate. These surrounding coding plates collectively determine the extended field of view. Through precise geometric design, the field of view of the front coding plate and the surrounding coding plates are seamlessly or partially overlapped. For example, when the front coding plate provides a 20° field of view to the left and right, the surrounding coding plates can further extend the field of view outward to 50° to the left and right, thus achieving a total field of view of approximately 100°, or about 50° to the left and right of the optical axis. The radiated signal is automatically received and encoded by the front coding plate or the corresponding surrounding coding plate according to its incident angle.

[0038] In summary, by employing a core structure consisting of a front encoder plate and four surrounding encoder plates with different acquisition fields of view, the geometric limitations of a single planar encoder plate are overcome at the physical level, significantly expanding the effective imaging field of view from the traditional approximately 40° to approximately 100°. This directly solves the core problems of existing equipment, such as low scanning efficiency and high risk of lateral missed detections due to narrow field of view, enabling the camera to scan a wider area. The composite structure allows the camera to simultaneously receive radiation signals from a large angle range both frontally and laterally, acquiring far more information in a single pass than traditional cameras. This provides the unique and necessary raw data guarantee for subsequent reconstruction of high-quality, wide-field-of-view images.

[0039] In one specific embodiment of this specification, a composite coded collimator is used to receive radiated signals through the acquisition fields corresponding to the front coded plate and the surrounding coded plates. Signals from the central region directly in front, for example, with an angle of less than approximately 20° to the optical axis, mainly pass through the coded pattern of the front coded plate. Signals from larger lateral angles, for example, with an angle of 20° to 50° to the optical axis, mainly pass through the coded patterns of the surrounding coded plates in the corresponding direction.

[0040] After signal reception, a coded projection image corresponding to the radiation signal can be generated on the detector. This coded projection image is a two-dimensional intensity distribution map formed on the position-sensitive detector after the radiation signal passes through the composite coded collimator. Its coding nature is reflected in the fact that, since the radiation must pass through specific holes on a specific coded plate to reach the detector, what is recorded on the detector is not a direct image of the radiation source, but a complex shadow pattern formed by the combined modulation of the patterns on the two coded plates. This image is a mixture of spatial distribution information and the coding key, serving as the input for subsequent decoding calculations.

[0041] Furthermore, the encoding pattern of the front encoding plate includes a random array, a uniform redundant array, or a modified uniform redundant array; the encoding pattern of the surrounding encoding plate includes a single hole or multiple holes.

[0042] Random arrays are coding patterns where the distribution of transmission apertures and shielding blocks is generated based on random or pseudo-random sequences. Their design is relatively simple, but their imaging performance, such as signal-to-noise ratio (SNR), is generally inferior to mathematically optimized deterministic subarrays. Uniform Redundant Arrays (URAs) are cyclic, deterministic two-dimensional binary arrays. Their core characteristic is that their periodic autocorrelation function has uniform sidelobes, and the ratio of the main lobe to the sidelobes (the SNR improvement factor) reaches its theoretical optimum. This requires the array size to be a prime number. Modified Uniformly Redundant Arrays (MURAs) are an important variant of URAs, with sizes that can be any odd number. MURAs also possess near-ideal "uniform redundancy" autocorrelation characteristics (sharp main lobe, flat and low-valued sidelobes) and are easier to implement in engineering, making them the most commonly used and preferred coding pattern for front-side coding boards.

[0043] A single-aperture pattern refers to an extremely simplified pattern where only one transmission aperture is formed within the effective area of ​​the surrounding encoding plate. Essentially, it transforms the surrounding encoding plate into a pinhole collimation point in a specific direction. Its advantage is that the projection is absolutely free of aliasing, making decoding and positioning easy, but its disadvantage is extremely low sensitivity. A multi-aperture pattern refers to a simplified pattern where a few (e.g., 2 or 5) transmission apertures are formed on the surrounding encoding plate. Compared to a single-aperture pattern, it significantly improves detection sensitivity by increasing the transmission area while maintaining a relatively simple and distinguishable projection pattern. One embodiment in this specification employs a typical multi-aperture design: "Asymmetric 5-aperture encoding," which further enhances the ability to distinguish signals from different angles through asymmetrical arrangement.

[0044] In practical applications, the front and surrounding coding plates in composite coded collimators face drastically different technical challenges due to their different spatial positions and functional roles. Using the same coding pattern will not achieve optimal overall performance. The front coding plate is responsible for central field-of-view imaging, requiring images with high resolution, high signal-to-noise ratio, and low artifacts. This necessitates that the coding pattern possess excellent autocorrelation properties mathematically to achieve accurate and stable decoding. The surrounding coding plates handle large-angle lateral fields of view; oblique incidence of radiation causes severe stretching and distortion of their projections onto the detector. Using complex patterns will result in severe aliasing and indistinguishability of projections from different angles, leading to decoding failures or severe image quality degradation.

[0045] Therefore, to simultaneously achieve high-quality imaging in the central region and effective signal acquisition in the extended region, differentiated coding strategies must be adopted for both. A mathematically optimized complex array is selected for the front coding board to ensure core performance. An extremely simplified pattern is chosen for the surrounding coding boards to ensure recognizability and decodeability of large-angle projections; this is key to solving the problem of blurred edges or inability to image in large-field-of-view imaging.

[0046] For specific implementation, please refer to Figure 3A , Figure 3A This is a schematic diagram of the encoder plate structure of a composite encoder collimator provided in one embodiment of this specification, wherein, Figure 3A The system includes a mask with a composite coded collimator. The mask consists of a front mask (top) and four side masks (left and right). The front mask has a coded pattern corresponding to the array, and the four side masks have coded holes. The four side masks are connected to the detector. In the coded pattern, white pixels represent transmission holes, and black pixels represent shielding blocks.

[0047] In summary, the use of optimized arrays such as MURA for the front encoding plate leverages its near-ideal autocorrelation properties, resulting in the highest signal-to-noise ratio gain, optimal spatial resolution, and minimal imaging artifacts when decoding and reconstructing the central field of view image, providing clear and reliable images for the core monitoring area. The use of single-aperture or simplified multi-aperture patterns for the surrounding encoding plates fundamentally overcomes the projection aliasing problem in large-angle imaging. The simplified projection characteristics ensure that even signals originating from edge angles can have their encoded shadows clearly recorded by the detector and accurately traced by the decoding algorithm, thus successfully transforming the extended field of view from unimageable to clearly imageable.

[0048] Furthermore, the acquisition field of view of the composite coding collimator is composed of the central acquisition field of view of the front coding plate and the extended acquisition field of view of the surrounding coding plates.

[0049] The central acquisition field of view can be understood as the spatial angular range capable of effective imaging, determined by the geometric position, aperture size, and distance from the detector of the front encoder plate. Centered on the system's imaging optical axis, this field of view is typically symmetrically distributed (approximately 20° to the left and right) and is the core area for the imaging system to acquire high-resolution, high signal-to-noise ratio images. Its boundary is defined by a line connecting the detector edge to the outermost edge of the front encoder aperture. The extended acquisition field of view can be understood as the spatial angular range capable of effectively acquiring radiation signals and contributing to imaging, determined by the geometric position, orientation, and encoder apertures of the surrounding encoder plates. This field of view is located outside the central acquisition field of view, typically starting at the edge of the central field of view and extending outwards to larger angles (e.g., from an angle of 20° to 50° with the optical axis). Its main function is to capture radiation signals from the sides, compensating for the insufficient coverage of the central field of view.

[0050] In practical applications, the acquisition field of view of the composite coded collimator is composed of the central acquisition field of view of the front coded plate and the extended acquisition field of view of the surrounding coded plates. It is not a simple addition, but rather, through precise geometric layout in system design, the extended field of view and the central field of view are closely connected, partially overlapped, or seamlessly connected in angular space, forming a single, wider-coverage total effective imaging area. During image reconstruction, signals from these two areas are processed uniformly and jointly participate in the reconstruction of a complete, large-field-of-view image.

[0051] See Figure 3B , Figure 3B This is a field of view diagram provided in one embodiment of the present specification, wherein FOV-1 represents the field of view determined by the front encoder plate; FOV-2 represents the field of view jointly determined by the four sides and the front encoder plate; and FOV-3 corresponds to the field of view determined by the four encoder plates.

[0052] like Figure 3A and Figure 3B As shown, taking a small hole on each side as an example, the pointing angle of the holes in the four-sided coding plate is defined. Let the angle between the central axis of the radiation emitted from the small holes in the four-sided coding plate and the system optical axis (the normal to the front coding plate) be α = 40°. The angle between this ray and the plane of the front coding plate is β = γ = 70°. Calculate the field of view angle for each zone: The single-sided angle δ of the central acquisition field of view (FOV-1) is: δ = 90° - γ = 20°. The partial angles ζ and η of the extended acquisition field of view are derived from geometric relationships: ζ = 20°, η = 10°. Field of view combination and total field of view calculation: The system's field of view on one side of the optical axis consists of three parts in sequence: δ (center), ζ (transition), and η (lateral). Therefore, the total field of view on one side is: δ + ζ + η = 50°. Finally, the total acquisition field of view of the composite coded collimator is: 2(δ + ζ + η) = 2(90° - α) = 100°.

[0053] Therefore, when a radiation source is located at 0° on the optical axis, its signal is mainly collected by the front plate (falling into FOV-1). When the radiation source is located at 40° on the optical axis, its signal is collected by specific surrounding plates (possibly falling into FOV-2 or FOV-3). All signals from different angles (0° to 50°), depending on their incident direction, are modulated by the front or surrounding coded plates, collectively forming a mixed coded projection image on the detector. During subsequent decoding, the system response model integrates the contributions of all plates to reconstruct a complete spatial distribution image covering a 100° range.

[0054] Based on this, through rigorous geometric design, the central 40° field of view is precisely combined with the extended 60° field of view, giving the system a total field of view of approximately 100°, which is 1.5 times larger than traditional solutions. This combination ensures continuous spatial coverage from the optical axis to the maximum deflection angle without any theoretical blind spots, completely solving the fundamental defects of narrow field-of-view devices, such as low scanning efficiency and easy to miss lateral sources, and perfectly matching the design goal of a "wide field of view" camera.

[0055] Furthermore, the radiation signal includes at least one of gamma rays, thermal neutrons, and fast neutrons.

[0056] In practical applications, traditional radiation imaging equipment often has limited functionality. Gamma cameras are insensitive to neutrons or have extremely weak responses, while neutron cameras experience performance degradation under strong gamma backgrounds. This limitation means that in complex real radiation fields (where gamma sources, neutron sources, or mixed sources may coexist), a single measurement cannot obtain comprehensive situational information. Therefore, the X-ray camera in the embodiments of this specification needs to be capable of distinguishing between different types of radiation.

[0057] Specifically, after generating the coded projection image corresponding to the radiation signal on the detector, the method further includes: using the detector to distinguish events in the coded projection image according to a pulse shape discrimination strategy, and obtaining at least one type of event among the gamma event corresponding to the gamma ray, the thermal neutron event corresponding to the thermal neutron, and the fast neutron event corresponding to the fast neutron.

[0058] In practical applications, the generated coded projection image is an unclassified raw data set that mixes all types of radiation signals. Directly decoding this mixed data would only yield a confused image where all radiation contributions are superimposed, making it impossible to distinguish source terms. This fails to meet the precise monitoring requirements for identifying radiation types, such as gamma sources, neutron sources, or mixed sources. Therefore, before image reconstruction, the raw data stream is pre-classified using the detector's own physical characteristics. The mixed coded projection image is logically decoupled into multiple clean subsets classified by particle type.

[0059] The pulse shape discrimination strategy refers to a signal processing algorithm or logic that identifies particle types based on the different time decay characteristics of fluorescent pulses generated by different charged particles or photons excited in the same scintillator. In the embodiments of this specification, the detector can distinguish events using the pulse shape discrimination strategy. An event refers to a complete radiation-particle interaction process recorded by the detector. Each event includes at least position information (X, Y coordinates on the detector), energy information (total pulse amplitude), and key time waveform information (pulse shape).

[0060] Event differentiation is the process by which the signal processing system (back-end electronics) in the detector acquires and analyzes the raw pulse waveform of each event in real time, and classifies it into gamma events, thermal neutron events, or fast neutron events based on its characteristic parameters such as decay time constant and rise time using preset PSD (Pulse Shape Discrimination) algorithms such as charge comparison method and pulse gradient analysis method.

[0061] In practical implementation, the detector assembly consists of a detector crystal, a silicon photomultiplier tube, and back-end electronics. The detector crystal is composed of a position-sensitive detector with the ability to distinguish between thermal neutrons, fast neutrons, and gamma rays, and can be composed of a single detector crystal or a composite detector crystal. For example, Cs2LiYCl6:Ce (cerium-doped cesium-lithium-yttrium chloride, in which the content of 6Li (lithium-6) is 95%) can be selected as the detector material (CLYC-6). This crystal can clearly distinguish gamma rays, fast neutrons, and thermal neutrons through pulse shape discrimination technology. Slow neutrons interact with CLYC-6 through the 6Li(n,α)3H reaction (neutron capture-splitting reaction). Tritium and alpha particles emitted from the crystal deposit approximately 4.78 MeV of energy in the crystal, thereby generating an optical signal of approximately 3.2 MeVee (MeV electron-equivalent). Fast neutrons can also be detected through the 35Cl(n,p) and 35Cl(n,α) reactions (exothermic nuclear reactions of natural chlorine-35 under neutron irradiation). The radiation deposits energy in a scintillator, producing fluorescence, which propagates along a light guide and is eventually collected by a silicon photomultiplier tube (SiPM). Back-end electronics systems acquire and process the data, identifying and imaging thermal neutrons, fast neutrons, and gamma rays.

[0062] In a specific embodiment of this specification, the detector SiPM and front-end electronics capture the complete voltage pulse waveform of an event. The processor calculates two key parameters of this waveform: the total integrated charge (Q_total, reflecting the total energy) and the partial integrated charge (Q_tail, reflecting the proportion of the slow component). In a preset two-dimensional scatter plot (e.g., Q_tail / Q_total vs. Q_total), the data points of the event will fall into different clustering regions: those falling into the low Q_tail / Q_total, continuous energy region are identified as gamma events. Those falling into the high Q_tail / Q_total region and forming clusters at specific energies are identified as thermal neutron events. Those falling into the middle Q_tail / Q_total region and with a wider energy distribution are identified as fast neutron events. Based on the identification results, the system stores the location (X,Y) information of the event in the gamma event list, the thermal neutron event list, or the fast neutron event list, respectively.

[0063] Based on this, a physically mixed coded projection was transformed into a list of logically pure events categorized by particle type. This provides the only feasible data foundation for subsequently generating crosstalk-free, independently interpretable radiation composition images.

[0064] Step 104: Determine the decoding information corresponding to the composite coded collimator, and perform decoding calculation on the coded projection image based on the decoding information to obtain the spatial distribution image corresponding to the radiation signal.

[0065] The decoded information can be understood as a precisely quantified system response model. It fully describes how radiation emitted from any point in space, after passing through every possible coded aperture on the composite coded collimator, ultimately generates a count probability or contribution weight on each pixel of the detector. This model is a comprehensive mathematical representation of the coded pattern, the three-dimensional geometry of the collimator, the pixel position of the detector, and possible non-ideal factors (such as incomplete shielding). It is a prerequisite and input for any decoding calculation.

[0066] Decoding computation can be understood as running a specific image reconstruction algorithm. Taking the system response model and the coded projection image (or a subset thereof after event differentiation) as input, it uses mathematical processes such as iteration or transformation to solve for the spatial intensity distribution (i.e., the image) that best matches the observed data. In practice, the decoding process processes the coded projection data obtained from the position detector to recover the distribution of the radiation source; this is also called image reconstruction. Image decoding reconstructs the distribution map of the radiation source using the autocorrelation characteristics of the coded collimator. Coding imaging decoding algorithms are divided into two categories: correlation decoding algorithms and maximum likelihood algorithms.

[0067] A spatial distribution image is the final output of the decoding calculation; it is a two-dimensional image. Its horizontal and vertical coordinates represent orientation angles or spatial locations (usually centered on the camera), and the grayscale value or color of a pixel represents the relative intensity of radiation in that direction. After event differentiation, this spatial distribution image can include gamma-ray spatial distribution images, thermal neutron spatial distribution images, or fast neutron spatial distribution images.

[0068] In practical applications, the encoded projected image is not a straightforward image, but rather the result of the convolution of spatial information and the encoding key. Without decoding, this image cannot be directly interpreted by human observers or decision-making systems, and thus cannot achieve the function of "imaging." Step 104 is equivalent to a decryption process. It uses the known key, i.e., the decoding information, to mathematically calculate and inversely solve for the most probable radiation source distribution that leads to the projected pattern. This transforms the unreadable encoded data into an intuitive and quantitatively analyzable spatial distribution image, ultimately achieving the goal of radiation source localization and visualization.

[0069] In a specific embodiment of this specification, after the camera design and manufacturing are completed, a precise three-dimensional model of the composite coded collimator (front MURA plate + surrounding perforated plate) is determined through precise measurement and theoretical calculation, including the position, size, and orientation of each hole. Combined with the detector's pixel layout, a system response matrix H is calculated. Each row of matrix H corresponds to a detector pixel i, and each column corresponds to a hypothetical source point j in space. The physical meaning of the matrix element H_{ij} is the probability that a unit intensity point source located at the j-th position in space will generate a count on the i-th pixel of the detector. This matrix H is the core decoding information. Decoding calculations are performed to obtain the final reconstructed image f, i.e., the spatial distribution image of the radiation source. See also... Figures 4A to 4C , Figure 4A This is a schematic diagram of the center of the field of view provided in one embodiment of this specification. Figure 4B This is a schematic diagram of an image in the middle of the field of view provided in one embodiment of this specification. Figure 4C This specification provides an embodiment of an image diagram of the edge of the field of view. Figure 4A It includes the projected image and the reconstructed image at the center of the field of view (0,0); Figure 4B This includes the projected image and the reconstructed image in the middle of the field of view (20,20); Figure 4C This includes the projected image and the reconstructed image at the edge of the field of view (50, 50). The (x, y) coordinates mentioned above represent relative spatial coordinates or pixel indices, used to quantitatively represent the different orientations of the point source within the camera's field of view.

[0070] Figure 4A , Figure 4B and Figure 4CThe left column of projected images shows the raw coded projected images formed by point sources on the detector. They appear as complex, blurry shadow patterns, making it impossible to directly locate the source. Figure 4A , Figure 4B and Figure 4C The reconstructed images in the right column show the results of decoding the left projection based on the decoded information. In the reconstructed images, the point source is clearly restored as a bright point, its position perfectly consistent with the simulation settings. This visually demonstrates the effectiveness of this step. These projected images and reconstructed images from different field-of-view angles confirm that the radiation imaging method based on a ray camera provided in this specification, by expanding the field of view (FOV) from 40° to 100°, possesses the ability to distinguish thermal neutrons, fast neutrons, and gamma rays, as well as rapid imaging and localization capabilities, meeting the requirements of neutron and gamma source term investigation tasks when neutron source term information is unknown.

[0071] Based on this, since the decoded information is calculated strictly according to the unique physical structure of the composite coded collimator, the decoding process can accurately understand the contributions of the complex coding on the front coded plate and the simple coding on the surrounding coded plates, thus accurately repositioning the signal in the mixed projection to its true spatial direction. This ensures accurate spatial positioning even at a large field of view of approximately 100°, solving the problem of the difficulty in achieving both a large field of view and high precision.

[0072] Furthermore, the decoding calculation of the encoded projection image based on the decoding information to obtain the spatial distribution image corresponding to the radiation signal includes: determining the projection data corresponding to the at least one type of event in the encoded projection image; decoding the projection data corresponding to the at least one type of event based on the decoding information to obtain the spatial distribution sub-image corresponding to the at least one type of event; and determining the spatial distribution image corresponding to the radiation signal based on the spatial distribution sub-image corresponding to the at least one type of event.

[0073] In this context, identifying projection data corresponding to at least one type of event in the coded projection image can be understood as separating and extracting a subset of data containing only specific types of radiation events from the original, mixed coded projection image, based on the type labels provided by pulse shape identification technology. For example, "projection data corresponding to gamma events" is a count distribution map formed by statistically analyzing the coordinate positions of all events identified as gamma rays by the PSD. It serves as the input for subsequent targeted image reconstruction.

[0074] A spatial distribution sub-image corresponding to at least one type of event can be understood as a two-dimensional image reconstructed from the projected data of one of the aforementioned types of events, after independently applying a decoding algorithm (such as the maximum likelihood expectation-maximization algorithm) and a system response model of a composite coded collimator. Each pixel value in this image represents an intensity estimate of that specific type of radiation in the corresponding direction in space. For example, bright spots in the spatial distribution sub-image of thermal neutrons only indicate the location of the thermal neutron source and are not affected by gamma or fast neutron signals.

[0075] Determining the spatial distribution image corresponding to the radiation signal is an "output and encapsulation" step. The system outputs the corresponding spatial distribution sub-image as the final output based on the number of event categories actually distinguished. The output result is flexible in form; it can be a single sub-image when there is only one type of event, or an image set or fused view when there are multiple types of events.

[0076] In practical applications, the original encoded projection image is a physically mixed but information-complete data volume, while end users require logically separated and intuitively independent component distribution maps. Directly decoding the entire mixed image as a single process would reconstruct a confused image where all radiation contributions are superimposed, making it impossible to distinguish particle types. This completely fails to meet the requirement of simultaneous discrimination. Therefore, a decoding process capable of handling multimodal information must be designed. In the embodiments of this specification, the complex multi-class imaging problem is decomposed into multiple parallel single-class imaging subtasks. This ensures that pure spatial information of each type of radiation can be extracted from the same set of mixed data, thereby solving the industry problem that single-function devices cannot provide comprehensive radiation field component analysis.

[0077] In a specific embodiment of this specification, it is assumed that there are two radiation sources in the scenario: a gamma source located near the simulated coordinates (20,20) and a neutron source located near (50,50), simultaneously emitting neutrons and accompanying gamma rays. The detector records the mixed events, and performs real-time differentiation on each event, classifying and labeling it as a gamma event, a thermal neutron event, or a fast neutron event. The system then generates three independent projection data maps: a gamma event projection map, a thermal neutron event projection map, and a fast neutron event projection map. Each map is similar to... Figures 4A-4C The projected images in the left column each contain only the count of the corresponding type of event.

[0078] The decoder loads an accurate system response model that encodes the geometry and shielding information of all coded apertures in the composite collimator. Iterative reconstruction of the gamma event projection map yields a sub-image of the gamma ray spatial distribution. This image is expected to have a strong bright spot at (20,20) and a weaker bright spot (from the accompanying gamma) at (50,50). Reconstruction of the thermal neutron event projection map yields a sub-image of the thermal neutron spatial distribution. This image is expected to have only one clear bright spot at (50,50). Reconstruction of the fast neutron event projection map yields a sub-image of the fast neutron spatial distribution. This image also has a bright spot at (50,50).

[0079] At this point, the system has obtained three reconstructed sub-images. Based on user instructions or default settings, the final spatial distribution image can be determined in several forms: For example, displaying three sub-images side-by-side on the screen simultaneously. Figures 4A-4C The reconstructed images in the right column are arranged by category, facilitating direct comparison of the distribution of different radiation components.

[0080] For example, by assigning different colors to three sub-images (such as gamma-red, thermal neutron-green, and fast neutron-blue) and superimposing them to generate a color fused image, the positions and overlap relationships of different types of radiation sources are clearly visible.

[0081] Based on this, by performing a separation-then-reconstruction operation, the mutual contamination pathways of different types of radiation signals in the image domain are completely eliminated. Each spatially distributed sub-image originates from its pure projection data, thus ensuring that the gamma image is free of neutron background and the neutron image is not affected by strong gamma fields. This provides a reliable data foundation for the accurate identification, quantitative analysis, and activity assessment of radiation sources, and solves the inherent ambiguity problem in mixed imaging.

[0082] Furthermore, the X-ray camera also includes an imaging unit, which includes an imaging receiving chamber extending along the imaging direction; the composite coding collimator is located in the imaging receiving chamber and in front of the detector along the imaging direction; wherein the composite coding collimator includes a front coding plate located on the front side in the imaging direction, and a surrounding coding plate connected to the edge of the front coding plate and extending along the imaging direction.

[0083] The imaging unit can be understood as the core module in a X-ray camera responsible for acquiring and encoding radiation signals. (See also...) Figure 5A , Figure 5A This is a schematic diagram of the structure of an imaging unit provided in one embodiment of this specification. It is typically a separate mechanical component, including a housing (since internal components are shown, ...). Figure 5AThe shell (in its unfolded state) contains all the internal optical and detection components. Its function is to form a sealed, light-proof space to house collimators, detectors, etc., and to ensure that they are protected from ambient light and stray radiation interference.

[0084] An imaging containment chamber is a cavity or channel extending along the imaging direction within the imaging unit. This chamber is typically rectangular or cylindrical, with its front opening for receiving radiated signals and its rear opening for mounting the detector. The inner walls of the chamber may be coated with absorbing materials to reduce scattering. Its "extending along the imaging direction" design ensures that the radiated signal can reach the detector unobstructed along the designed optical path.

[0085] The imaging direction refers to the main direction in which the radiation signal enters the camera and eventually reaches the detector. Typically, this direction coincides with the system's optical axis and is perpendicular to the plane of the front encoder plate. It serves as the reference for defining front and back in spatial relationships. For example, if the composite encoder collimator is located in front of the detector along the imaging direction, then with the imaging direction as a reference, the side closer to the radiation source is considered front, and the side closer to the camera interior or rear end is considered back. Therefore, the composite encoder collimator being located in front of the detector along the imaging direction means that the radiation signal first passes through the composite encoder collimator before reaching the detector; this is the basic optical path sequence for coded aperture imaging.

[0086] In the mechanical construction of the composite coded collimator, see Figure 5B , Figure 5B This is a schematic diagram of the internal structure of an imaging unit provided in this specification. The front encoding plate is a flat plate located at the frontmost side; the surrounding encoding plates are side walls that extend backward (i.e., towards the detector) from the four edges of this flat plate. These side walls, together with the front plate, form a box or cylinder that is open at one end and may be open or connected to other structures at the other end, thereby forming an extended field of view structure capable of receiving lateral signals.

[0087] like Figure 5A and Figure 5B As shown, the imaging unit's housing contains a hollow imaging chamber. The front opening of the chamber may be covered by a transmission window or directly exposed. A composite coded collimator is installed inside the chamber near the front end. Specifically, it can be seen that: The front coding plate, a flat plate with a regular coding pattern (possibly a MURA pattern), is fixed at or near the front of the chamber. The surrounding coding plates, with four side plates (top, bottom, left, and right) connected to the edge of the front coding plate and extending rearward, may be mounted at a slight angle to create an extended field of view. The detector assembly is located behind the composite coding collimator, further into the chamber along the imaging direction. The detector typically includes a scintillator crystal and a photoelectric sensor array, fixed to a circuit board or bracket. The imaging unit may also include a composite shielding plate located behind the detector to block radiation incident from the rear.

[0088] pass Figure 5A and Figure 5B The diagram illustrates that the radiated signal enters from the left side (front of the imaging direction), first passing through the composite coded collimator (front side plate + surrounding plates), then forming a coded projection on the detector plane, and finally being recorded by the detector. The rearward extension of the surrounding coded plates mechanically provides a channel for lateral radiation to enter, while optically defining the range of the extended field of view.

[0089] Based on this, by integrating the composite coded collimator and detector into a rigid imaging unit with a dedicated housing chamber, the relative positions of all key optical components are calibrated and permanently fixed during assembly. This significantly reduces the risk of optical path deviation due to component loosening, thermal expansion and contraction, or external impacts, ensuring the camera's long-term stability in harsh environments such as fieldwork and mobile operation. The design of the four coded plates connected to the edges and extending along the imaging direction is the physical basis for forming an extended acquisition field of view. This allows lateral radiation to pass through the coded holes in the four plates and be recorded by the detector, an indispensable mechanical realization of a large field of view.

[0090] Furthermore, the X-ray camera also includes a composite shielding plate; the composite shielding plate is positioned behind the detector along the imaging direction.

[0091] The composite shielding plate can be understood as a plate-like component located behind the detector, specifically designed to shield radiation. The term "composite" refers to the composite materials used, meaning it is made of multiple materials with high shielding capabilities against different types of radiation (e.g., high-density polyethylene (HDPE) with a large fast neutron absorption cross-section, cadmium plates sensitive to thermal neutrons, and tungsten-based materials with high gamma shielding efficiency). Unlike the composite coded collimator, the sole purpose of the shielding plate is complete shielding; therefore, it is typically a solid plate without any transmission holes. The composite shielding plate is placed behind the detector along the imaging direction, mounted flush against the back (non-receiving surface) of the detector or at a very small distance. Its function is to form a barrier, ensuring that any radiation attempting to penetrate from the rear of the camera is absorbed before reaching the detector's sensitive volume.

[0092] In practical applications, the detector not only receives target signals passing through the coded collimator from the designed field of view (front and all sides), but may also be affected by stray radiation or background radiation from behind, to the side and rear of the camera, or other non-field of view directions. If these non-target signals are also recorded by the detector, they will be directly mixed into the generated coded projection image as background noise that cannot be distinguished by the decoding algorithm. This will lead to two serious consequences: First, the noise will reduce the signal-to-noise ratio of the projection image, making the spatial distribution image reconstructed by subsequent decoding blurry and losing details. Second, strong background from the rear may form non-coded uniform bright spots or specific distributions on the detector. These pseudo-signals will be mistaken by the decoding algorithm as real radiation sources from the front field of view, thus creating false hotspots in the reconstructed image, leading to positioning errors and misjudgments. Therefore, the fundamental purpose of setting up a composite shielding plate behind the detector is to actively and effectively block all radiation from the rear of the imaging direction, thereby purifying the signal received by the detector and ensuring that the information in the coded projection image only comes from the approximately 100° front field of view defined by the composite coded collimator. This is a prerequisite for obtaining high-fidelity and high-reliability reconstructed images, and it solves the inherent defect of open detector structures being susceptible to environmental background interference.

[0093] In one specific embodiment of this specification, the imaging chamber houses, in sequence along the imaging direction (from front to back): a composite coded collimator, a detector, and a composite shielding plate. The composite shielding plate is mounted flush against the rear circuit board or mechanical support of the detector, or directly fixed to the rear wall of the chamber. There is typically no functional gap between it and the detector, designed to maximize shielding effectiveness. Assume that when the camera is operating, there is an unrelated radiation source in the environment behind it. Without the composite shielding plate, the radiation emitted by this source might directly illuminate the back of the detector, generating a diffuse or concentrated background count. These counts would be added directly to the projected image without any coded pattern, contaminating the data. With the composite shielding plate installed, the rays from the rear radiation source are almost completely absorbed by the shielding plate. The count rate recorded by the detector decreases significantly, and the remaining background mainly consists of weak signals that are difficult to shield, such as cosmic rays, which remain stable and extremely low. This ensures that the signal changes in the coded projected image accurately reflect the intensity and distribution of the target radiation source within the forward field of view, rather than being distorted by interference from the rear environment.

[0094] Based on this, by setting a composite shielding plate behind the detector, the strong background radiation from the rear is effectively blocked, minimizing the detector's operating background. This makes the relatively weak real target signals from the front field of view stand out more in the projected data, resulting in a spatial distribution image with a cleaner background, sharper hotspots, and richer details after decoding and reconstruction, significantly improving weak source detection capability and image quality.

[0095] Furthermore, the X-ray camera also includes a camera unit and a processing and display unit; the camera unit acquires optical images and sends the optical images to the processing and display unit; the processing and display unit fuses the spatial distribution image with the optical image and displays the image.

[0096] The camera unit refers to the optical imaging module integrated into the X-ray camera, typically including a lens, image sensor, and drive circuitry. Its function is to acquire visible light or infrared digital images simultaneously with radiation imaging, from the same location and viewing angle, providing a spatially registered background map for the radiation distribution map. It is an independent parallel acquisition system compared to radiation detection.

[0097] The processing and display unit is a hardware and software module that integrates data processing and graphics display functions. It may consist of an embedded processor, a graphics processor, a display screen, and dedicated software.

[0098] The processing and display unit receives the spatial distribution image from the imaging unit and the optical image from the camera unit, performs image registration, alignment, and fusion algorithms (such as transparency overlay, pseudo-color mapping, contour overlay, etc.) to generate a fused image. The generated fused image, or multiple images side by side (original radiometric image, optical image, fused image), is displayed in real time on an integrated screen or external monitor.

[0099] In one specific embodiment of this specification, when the operator presses the shutter or starts scanning, the composite coded collimator and detector begin to operate, integrating over a set time to generate coded projection data, which is then decoded into a spatial distribution image (e.g., a pseudo-color image showing two hotspots). Simultaneously, the camera unit captures a high-resolution optical photograph, recording the actual scene the camera's current line of sight is aligned with (e.g., a corner of a room containing pipes and shelves). The processing and display unit (e.g., host computer software) simultaneously receives two images with timestamps and preliminary orientation data. Using pre-calibrated intrinsic and extrinsic parameters of the camera—the relative position and viewing angle between the radiation detector and the optical camera—or through a feature point matching algorithm, each pixel of the spatial distribution image is automatically mapped to its corresponding geographical location in the optical image. Regions in the spatial distribution image with intensity exceeding a threshold are then rendered as red semi-transparent blocks and precisely superimposed onto the corresponding areas in the optical photograph. The intensity value can be represented by the brightness or transparency gradient of the blocks. The final fused image is displayed on the camera's built-in screen or a connected tablet computer. Instead of seeing abstract, pseudo-colored dots, the operator sees a realistic photograph of the scene, with prominent red blocks highlighting pipe valves and a package on a shelf. The operator can immediately understand that radiation source A is located near that valve, possibly originating from radioactive material deposited inside the pipe; radiation source B is located inside that specific package. This allows subsequent response actions (such as shielding, marking, and retrieval) to be precisely and quickly targeted, eliminating the need for tedious comparisons between abstract images and the actual environment.

[0100] Based on this, by integrating the camera unit and the processing and display unit and performing fusion display, the on-site visualization of radiation information and the intuitiveness of decision-making are realized, improving the accuracy and traceability of data recording and enhancing the multi-tasking adaptability and ease of operation of the equipment.

[0101] This specification provides a radiation imaging method based on a X-ray camera. The X-ray camera includes a composite coded collimator and a detector. The composite coded collimator includes a front coded plate and four surrounding coded plates, with different acquisition fields of view for the front and surrounding coded plates. The method includes: receiving radiation signals using the acquisition fields of view corresponding to the front and surrounding coded plates respectively through the composite coded collimator; generating a coded projection image corresponding to the radiation signals on the detector; determining the decoding information corresponding to the composite coded collimator; and performing decoding calculations on the coded projection image based on the decoding information to obtain a spatial distribution image corresponding to the radiation signals. By constructing a composite coded collimator using front and surrounding coded plates with different acquisition fields of view, a composite encoder can be used to combine the acquisition fields of view of the two coded plates to receive radiation signals, thereby expanding the acquisition field of view and solving the problem of low efficiency and inaccuracy in radiation detection due to narrow field of view. After signal reception by the composite coded collimator, a coded projection image with a large field of view mixing characteristic is generated on the detector. Subsequently, the encoded projection image is decoded and calculated using the decoded information to reconstruct the spatial distribution image of the radiation signal, thereby enabling the rapid and accurate acquisition of panoramic images of the radiation field within an ultra-large field of view and improving the efficiency of radiation detection.

[0102] Corresponding to the above method embodiments, this specification also provides embodiments of a radiation imaging device based on a X-ray camera. Figure 6 A schematic diagram of a radiation imaging device based on a ray camera, according to one embodiment of this specification, is shown. Figure 6 As shown, the X-ray camera includes a composite coding collimator and a detector. The composite coding collimator includes a front coding plate and four surrounding coding plates. The front coding plate and the four surrounding coding plates have different fields of view. The device includes: Encoding module 602 is configured to receive radiation signals through the composite encoding collimator using the acquisition fields corresponding to the front encoding plate and the four surrounding encoding plates, and generate an encoded projection image corresponding to the radiation signals on the detector. The decoding module 604 is configured to determine the decoding information corresponding to the composite coded collimator, and perform decoding calculations on the coded projection image based on the decoding information to obtain the spatial distribution image corresponding to the radiation signal.

[0103] Optionally, the radiation signal includes at least one of gamma rays, thermal neutrons, and fast neutrons.

[0104] Optionally, the device further includes a differentiation module configured to differentiate events in the coded projection image by means of the detector according to a pulse shape discrimination strategy, and obtain at least one type of event among the gamma event corresponding to the gamma ray, the thermal neutron event corresponding to the thermal neutron, and the fast neutron event corresponding to the fast neutron.

[0105] Optionally, the decoding module 604 is configured to determine the projection data corresponding to the at least one type of event in the encoded projection image; decode the projection data corresponding to the at least one type of event based on the decoding information to obtain a spatial distribution sub-image corresponding to the at least one type of event; and determine the spatial distribution image corresponding to the radiation signal based on the spatial distribution sub-image corresponding to the at least one type of event.

[0106] Optionally, the X-ray camera further includes an imaging unit, which includes an imaging receiving chamber extending along the imaging direction; the composite coding collimator is located in the imaging receiving chamber and in front of the detector along the imaging direction; wherein the composite coding collimator includes a front coding plate located on the front side in the imaging direction, and a surrounding coding plate connected to the edge of the front coding plate and extending along the imaging direction.

[0107] Optionally, the X-ray camera further includes a composite shielding plate; the composite shielding plate is positioned behind the detector along the imaging direction.

[0108] Optionally, the encoding pattern of the front encoding plate includes a random array, a uniform redundant array, or a modified uniform redundant array; the encoding pattern of the surrounding encoding plate includes a single hole or multiple holes.

[0109] Optionally, the X-ray camera further includes a camera unit and a processing and display unit; the camera unit acquires optical images and sends the optical images to the processing and display unit; the processing and display unit fuses the spatial distribution image with the optical image and displays the image.

[0110] Optionally, the acquisition field of view of the composite coding collimator is composed of the central acquisition field of view of the front coding plate and the extended acquisition field of view of the surrounding coding plates.

[0111] The above is a schematic scheme of a radiation imaging device based on a ray camera according to this embodiment. It should be noted that the technical solution of this radiation imaging device based on a ray camera belongs to the same concept as the technical solution of the radiation imaging method based on a ray camera described above. For details not described in detail in the technical solution of the radiation imaging device based on a ray camera, please refer to the description of the technical solution of the radiation imaging method based on a ray camera described above.

[0112] Corresponding to the above method embodiments, this specification also provides an embodiment of a X-ray camera. Figure 7 A schematic diagram of the structure of a X-ray camera according to one embodiment of this specification is shown. Figure 7 As shown, the X-ray camera 70 includes an imaging unit 702, which includes a composite coded collimator 7022 and a detector 7024. The composite coded collimator includes a front coded plate and a perimeter coded plate, and the front coded plate and the perimeter coded plate have different fields of view. The imaging unit 702 is used to generate a spatial distribution image according to any of the above-mentioned radiation imaging methods based on a ray camera.

[0113] In one embodiment, a radiation signal (containing at least one of gamma rays, thermal neutrons, and fast neutrons) is incident from the front of the camera and first reaches a composite coded collimator 7022 within the imaging unit 702. This collimator uses its front coded plate to receive signals from the central field of view directly in front and its surrounding coded plates to receive signals from the laterally extended field of view, thereby achieving a wide field of view coverage of approximately 100°. After passing through a specific coded pattern (such as a front MURA array or a surrounding multi-aperture array) on the collimator, the signal is spatially modulated to form a "coded projection" carrying directional information. The modulated radiation signal reaches the detector 7024 (preferably a CLYC position-sensitive detector with pulse shape discrimination capability). The detector converts each incident particle into a complete pulse waveform signal containing information such as position and energy. The internal processing unit then performs real-time pulse shape discrimination analysis on each event, classifying it according to waveform characteristics into at least one of gamma events, thermal neutron events, or fast neutron events, and generating a classified event list.

[0114] In one embodiment, the processing unit calls a pre-stored system response model (decoding information) that precisely matches the composite coded collimator 7022, and performs independent decoding calculations on the classified event list (e.g., using MLEM, Maximum-Likelihood Expectation-Maximization). This process inverts the coded projection data into the spatial distribution of the radiation source, ultimately generating at least one (or a set of) clear spatial distribution images, each corresponding to a different type of radiation. The X-ray camera 70 typically also integrates a camera unit and a processing and display unit. During operation, the camera unit simultaneously acquires visible light or infrared images of the scene. The processing and display unit automatically registers and fuses the decoded spatial distribution image with the optical image (e.g., superimposing the radiation hotspot in pseudo-color onto the real-world image), and displays the fused image on the screen in real time, allowing the operator to intuitively see the precise location of the radiation source in the real environment.

[0115] In summary, through the coordinated work of its imaging unit and other components, the X-ray camera automatically completes the entire process from large-field-of-view radiation signal acquisition, real-time multi-particle identification, high-precision image reconstruction to intuitive fusion display, achieving rapid, accurate, and visualized radiation imaging and positioning functions.

[0116] Figure 8 A structural block diagram of a computing device 800 according to one embodiment of this specification is shown. The components of the computing device 800 include, but are not limited to, a memory 810 and a processor 820. The processor 820 is connected to the memory 810 via a bus 830, and a database 850 is used to store data.

[0117] The computing device 800 also includes an access device 840, which enables the computing device 800 to communicate via one or more networks 860. Examples of these networks include Public Switched Telephone Network (PSTN), Local Area Network (LAN), Wide Area Network (WAN), Personal Area Network (PAN), or combinations of communication networks such as the Internet. The access device 840 may include one or more of any type of wired or wireless network interface (e.g., a network interface card (NIC)), such as an IEEE 802.11 Wireless Local Area Network (WLAN) wireless interface, a Wi-MAX (Worldwide Interoperability for Microwave Access) interface, an Ethernet interface, a Universal Serial Bus (USB) interface, a cellular network interface, a Bluetooth interface, or a Near Field Communication (NFC) interface.

[0118] In one embodiment of this specification, the above-described components of the computing device 800 and Figure 8 Other components, not shown, can also be connected to each other, for example, via a bus. It should be understood that... Figure 8 The block diagram of the computing device shown is for illustrative purposes only and is not intended to limit the scope of this specification. Those skilled in the art can add or replace other components as needed.

[0119] The computing device 800 can be any type of stationary or mobile computing device, including mobile computers or mobile computing devices (e.g., tablet computers, personal digital assistants, laptop computers, notebook computers, netbooks, etc.), mobile phones (e.g., smartphones), wearable computing devices (e.g., smartwatches, smart glasses, etc.) or other types of mobile devices, or stationary computing devices such as desktop computers or personal computers (PCs). The computing device 800 can also be a mobile or stationary server.

[0120] The processor 820 is configured to execute the following computer-executable instructions, which, when executed by the processor, implement the steps of the radiation imaging method based on the X-ray camera described above.

[0121] The above is a schematic representation of a computing device according to this embodiment. It should be noted that the technical solution of this computing device belongs to the same concept as the aforementioned radiation imaging method based on a ray camera. Details not described in detail in the technical solution of the computing device can be found in the description of the aforementioned radiation imaging method based on a ray camera.

[0122] An embodiment of this specification also provides a computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of the radiation imaging method based on a ray camera described above.

[0123] The above is an illustrative scheme of a computer-readable storage medium according to this embodiment. It should be noted that the technical solution of this storage medium belongs to the same concept as the technical solution of the radiation imaging method based on a X-ray camera described above. For details not described in detail in the technical solution of the storage medium, please refer to the description of the technical solution of the radiation imaging method based on a X-ray camera described above.

[0124] An embodiment of this specification also provides a computer program product, including a computer program or instructions that, when executed by a processor, implement the steps of the above-described radiation imaging method based on a X-ray camera.

[0125] The above is an illustrative scheme of a computer program product according to this embodiment. It should be noted that the technical solution of this computer program product and the technical solution of the radiation imaging method based on a X-ray camera described above belong to the same concept. For details not described in detail in the technical solution of the computer program product, please refer to the description of the technical solution of the radiation imaging method based on a X-ray camera described above.

[0126] The foregoing has described specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0127] The computer instructions include computer program code, which may be in the form of source code, object code, executable file, or certain intermediate forms. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording media, USB flash drive, portable hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium may be appropriately added or removed according to the requirements of patent practice. For example, in some regions, according to patent practice, computer-readable media may not include electrical carrier signals and telecommunication signals.

[0128] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that the embodiments in this specification are not limited to the described order of actions, because according to the embodiments in this specification, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in this specification are all preferred embodiments, and the actions and modules involved are not necessarily essential to the embodiments in this specification.

[0129] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0130] The preferred embodiments disclosed above are merely illustrative of this specification. Optional embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the embodiments described in this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the embodiments, thereby enabling those skilled in the art to better understand and utilize this specification.

Claims

1. A radiation imaging method based on a X-ray camera, characterized in that, The X-ray camera includes a composite coding collimator and a detector. The composite coding collimator includes a front coding plate and a perimeter coding plate. The front coding plate and the perimeter coding plate have different fields of view. The method includes: The composite coding collimator receives radiation signals using the acquisition fields corresponding to the front coding plate and the four surrounding coding plates, and generates a coded projection image corresponding to the radiation signals on the detector. Determine the decoding information corresponding to the composite coded collimator, and perform decoding calculations on the coded projection image based on the decoding information to obtain the spatial distribution image corresponding to the radiation signal.

2. The method according to claim 1, characterized in that, The radiation signal includes at least one of gamma rays, thermal neutrons, and fast neutrons.

3. The method according to claim 2, characterized in that, After generating the coded projection image corresponding to the radiation signal on the detector, the method further includes: The detector distinguishes events in the coded projection image according to a pulse shape discrimination strategy, thereby obtaining at least one type of event among the gamma events corresponding to the gamma rays, the thermal neutron events corresponding to the thermal neutrons, and the fast neutron events corresponding to the fast neutrons.

4. The method according to claim 3, characterized in that, Based on the decoded information, the encoded projection image is decoded and calculated to obtain the spatial distribution image corresponding to the radiation signal, including: Determine the projection data corresponding to the at least one type of event in the encoded projection image; Based on the decoding information, the projection data corresponding to the at least one type of event is decoded to obtain the spatial distribution sub-image corresponding to the at least one type of event; The spatial distribution image corresponding to the radiation signal is determined based on the spatial distribution sub-image corresponding to the at least one type of event.

5. The method according to claim 1, characterized in that, The X-ray camera also includes an imaging unit, which includes an imaging receiving chamber extending along the imaging direction. The composite coded collimator is located within the imaging containment cavity and is positioned in front of the detector along the imaging direction; The composite coding collimator includes a front coding plate located on the front side in the imaging direction, and a four-sided coding plate connected to the edge of the front coding plate and extending along the imaging direction.

6. The method according to claim 5, characterized in that, The X-ray camera also includes a composite shielding plate; The composite shielding plate is placed behind the detector along the imaging direction.

7. The method according to claim 1, characterized in that, The encoding pattern of the front encoding plate includes a random array, a uniform redundant array, or a modified uniform redundant array. The coding pattern of the four-sided coding plate includes single holes or multiple holes.

8. The method according to claim 1, characterized in that, The X-ray camera also includes a camera unit and a processing and display unit; The camera unit acquires optical images and sends the optical images to the processing and display unit. The processing and display unit fuses the spatial distribution image with the optical image and then displays it.

9. The method according to any one of claims 1-8, characterized in that, The acquisition field of view of the composite coding collimator is composed of the central acquisition field of view of the front coding plate and the extended acquisition field of view of the surrounding coding plates.

10. A ray camera, characterized in that, The X-ray camera includes an imaging unit, which includes a composite coding collimator and a detector. The composite coding collimator includes a front coding plate and a four-sided coding plate, and the front coding plate and the four-sided coding plate have different acquisition fields of view. The imaging unit is used to generate a spatial distribution image using the radiation imaging method based on a ray camera according to any one of claims 1-9.

11. A computing device, characterized in that, include: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions, which, when executed by the processor, implement the steps of the radiation imaging method based on a X-ray camera as described in any one of claims 1 to 9.

12. A computer-readable storage medium, characterized in that, It stores computer-executable instructions that, when executed by a processor, implement the steps of the radiation imaging method based on a ray camera as described in any one of claims 1 to 9.

13. A computer program product, characterized in that, Includes a computer program or instructions that, when executed by a processor, implement the steps of the radiation imaging method based on a X-ray camera as described in any one of claims 1 to 9.

Images