Imaging system for three-dimensional source localization

Abstract

An imaging system includes a detector configured to obtain radiation data from one or more sources and a controller. The controller is configured to define a plurality of buffers based on at least one initial condition. The radiation data includes a plurality of events. The controller is configured to receive individual events of the plurality of events and determine whether the individual events fall within a designated current buffer. Each event of the plurality of events in the current buffer is corrected for pose and aligned in a common two-dimensional space. The plurality of events in the current buffer are reconstructed into a three-dimensional space, the reconstruction being performed once for each of the plurality of buffers. The controller is configured to create a three-dimensional image based in part on the reconstruction in the three-dimensional space.

Description

[0001] Statement regarding federally funded research or development

[0002] This invention was completed with government support under Agreement No. HDTRA1-19-C-0025 granted by the U.S. Department of Defense. The U.S. government may possess certain rights in this invention. Technical Field

[0003] This disclosure generally relates to imaging systems used for source localization. Background Technology

[0004] Sources emitting radiation can be found in a variety of settings, including but not limited to power plants and nuclear medicine facilities. Multidirectional detectors sensitive to radiation emitted from all directions can be used to accurately pinpoint the location of sources of interest. The emitted radiation consists of multiple individual events. These individual events are captured by the multidirectional detector and are generally reconstructed one by one in full three-dimensional space. However, reconstruction in three-dimensional space is inherently computationally intensive. Furthermore, this computational burden increases linearly with the number of image elements employed. Summary of the Invention

[0005] This document discloses an imaging system with a detector configured to acquire radiation data from one or more sources. A controller is configured to receive radiation data comprising multiple events. The controller has a processor and a tangible, non-transitory memory on which instructions are recorded. Execution of the instructions by the processor causes the controller to define multiple buffers based on one or more initial conditions and designate one of the buffers as the current buffer. The controller is configured to receive an individual event from the multiple events and determine whether that individual event falls within the current buffer.

[0006] The controller is configured to align multiple events in the current buffer in a common 2D space. The multiple events in the current buffer are then reconstructed into 3D space, with the reconstruction performed once for each of the multiple buffers. The controller is configured to create a 3D image in part based on the reconstruction in 3D space. Before aligning the multiple events in 2D space, the controller is configured to perform this process for each of the multiple events in the current buffer (on an event-by-event basis) for the pose.

[0007] Correcting multiple events within the current buffer involves time-stamping the events with corresponding event times, obtaining the corresponding detector pitch, yaw, and roll at the corresponding event times, and shifting the events in angular space to correspond to the detector pitch, yaw, and roll. After reconstructing the multiple events in the current buffer in 3D space, the controller is configured to designate another of the multiple buffers as the current buffer.

[0008] In some embodiments, at least one initial condition is time-based, such that the current buffer is within a predefined start time and a predefined end time, and the individual event defines the event time. When the event time is within the predefined start time and predefined end time, the individual event falls into the current buffer. In some embodiments, at least one initial condition is distance-based, such that the current buffer defines a corresponding buffer position, and the individual event defines an event position. When the corresponding distance between the event position and the corresponding buffer position is less than or equal to a threshold distance, the individual event falls into the current buffer.

[0009] Initial conditions include the update frequency of multiple buffers. The update frequency can be between approximately 0.5 and 3 seconds. The detector can be configured to be position-sensitive. Aligning multiple events in two-dimensional space can include representing multiple events in the current buffer as corresponding Compton cones and overlapping the corresponding Compton cones together in two-dimensional space. Reconstructing multiple events into three-dimensional space can include determining the average global position for the current buffer, which is the average of the corresponding event positions for the multiple events in the current buffer.

[0010] Reconstructing multiple events into 3D space involves representing the 3D space using 3D voxels and obtaining the corresponding angle between each of the 3D voxels and the average global position in the 3D space. Reconstructing multiple events into 3D space also includes obtaining the corresponding pixel value from the current buffer based on the corresponding angle, the corresponding pixel value being represented by the corresponding Compton cone, and adding the corresponding contribution of the pixel value to the 3D voxel.

[0011] This paper discloses a method for operating an imaging system having a detector configured to acquire radiation data and a controller having a processor and a tangible, non-transitory storage on which instructions are recorded. The method includes defining a plurality of buffers based on at least one initial condition and designating one of the buffers as the current buffer via the controller. The radiation data includes a plurality of events. The method includes receiving the radiation data via the controller and determining whether an individual event among the plurality of events falls within the current buffer. The method includes aligning the plurality of events in the current buffer in a two-dimensional space and reconstructing the plurality of events in the current buffer in a three-dimensional space via the controller, the reconstruction being performed once for each of the plurality of buffers. A three-dimensional image is created, in part, based on the reconstruction in three-dimensional space via the controller.

[0012] The above-mentioned features and advantages of the invention, as well as other features and advantages, will become apparent from the following detailed description of the best mode for carrying out the invention, taken in conjunction with the accompanying drawings. Attached Figure Description

[0013] Figure 1 It is a schematic diagram of an imaging system with a detector and a controller;

[0014] Figure 2 It is by Figure 1 A diagram illustrating an example of source localization performed by an imaging system;

[0015] Figure 3 It is possible to be Figure 1 A flowchart of an example method executed by the controller; and

[0016] Figure 4 yes Figure 3 A schematic example illustration of a portion of the method, including the reconstruction of radiation events from two-dimensional space to three-dimensional space.

[0017] Representative embodiments of this disclosure are shown by way of non-limiting example in the accompanying drawings and are described in more detail below. However, it should be understood that the novel aspects of this disclosure are not limited to the specific forms shown in the drawings listed above. Rather, this disclosure is intended to cover modifications, equivalents, combinations, sub-combinations, substitutions, groupings, and alternatives that fall within the scope of this disclosure, such as those covered by the appended claims. Detailed Implementation

[0018] Referring to the accompanying drawings, similar reference numerals indicate similar components. Figure 1 An imaging system 10 having an imaging device 12 is schematically illustrated. The imaging device 12 includes a detector 14 configured to detect radiation emitted from multiple directions. The detector 14 may include a semiconductor, such as, for example, a zinc cadmium telluride (CdZnTe) compound. The detector 14 may include a Compton camera, which utilizes Compton scattering to determine the spatial origin of the observed radiation. The detector 14 may employ other types of sensor technology available to those skilled in the art.

[0019] refer to Figure 1 Detector 14 is configured to acquire position-sensitive radiation data from at least one source 16 of interest (such as a first source 18 and a second source 20). The source 16 of interest may be a gamma-emitting radioactive isotope. The source 16 of interest may emit alpha, beta, and electromagnetic radiation, neutrons, or other types of radiation known to those skilled in the art. In one example, the source 16 of interest is a gamma-emitting Cesium-137. Detector 14 is configured to be time-sensitive and records the radiation data as a function of time. In the case of gamma rays, each photon may be involved in multiple interactions. Detector 14 may be in motion while capturing radiation data. For example, detector 14 may be carried by a user or mounted on a remotely controlled mobile platform (not shown).

[0020] refer to Figure 1 Imaging device 12 may include an optical camera 22 configured to capture optical images of the source of interest 16. Spatial information regarding both overall position and pose can be obtained from a variety of methods available to those skilled in the art. Imaging device 12 may include a laser rangefinder 24 configured to determine the distance to a target, for example, by sending a laser pulse in a narrow beam toward the target and measuring the time it takes for the pulse to reflect from the target and return. Imaging device 12 may include a GPS (Global Positioning System) unit 26 or other devices suitable for transmitting the overall position coordinates of detector 14. Imaging device 12 may employ visual odometry, in which the position and pose of an object are estimated from a sequence of images. Visual odometry information may be collected using a single stereo camera and / or dual stereo cameras and may include color information (e.g., RGB) and depth information (e.g., RGB-D).

[0021] Imaging device 12 may include a spectrometer (not shown) that detects the intensity (counts) of radiation relative to the energy distribution of the corresponding radiation. Imaging device 12 may include associated circuitry or electronics (not shown) suitable for the application at hand. For example, the circuitry may include photomultiplier tubes, silicon photodiodes, other photon-to-electron conversion devices, high-voltage power supplies, preamplifiers, amplifiers, and analog-to-digital converters (ADCs). Imaging system 10 may take many different forms and include multiple and / or alternative components and facilities.

[0022] refer to Figure 1 The imaging system 10 includes a controller C, which is operatively connected to and configured to control the operation of the imaging device 12. (Reference) Figure 1 The controller C includes at least one processor P and at least one memory M (or any non-transitory tangible computer-readable storage medium) recorded thereon for executing method 200, for reconstructing a three-dimensional image or distribution of the source 16 of interest, at least in part, based on the radiation data. Method 200 in Figure 3 As shown and described below, the memory M can store a set of controller-executable instructions, and the processor P can execute the set of controller-executable instructions stored in the memory M.

[0023] As described below, imaging system 10 employs a combined 2D-to-3D approach, which significantly reduces the computational burden of 3D spatial imaging. By merging events together and then projecting them into 3D space to obtain a complete 3D image, imaging system 10 uses 2D imaging data (e.g., gamma-ray) to obtain a 3D projection. Events are first imaged in a common 2D angular space and corrected for the rotating detector pose. Changes in detector pose can be recorded as roll, pitch, and yaw, which are used to translate detector events to a common, comprehensive reference frame that allows for the 2D-to-3D reconstruction process. Imaging system 10 enables full 3D imaging (e.g., gamma-ray imaging) on ​​a mobile platform with low computational resources.

[0024] Controller C can be configured to control the operation of detector 14 and the acquisition, processing, and storage of radiation data. Detector 14 and / or controller C can be configured to record corresponding count sequences as a function of time or spatial location (e.g., 1 = count and 0 = no count). Controller C (along with processor P and memory M) can be an integral part of imaging device 12. Alternatively, controller C (along with processor P and memory M) can be a separate module communicating with imaging device 12 via network 30. Display device 32 (such as a tablet computer) can be wirelessly connected to controller C (e.g., via network 30) for real-time display of images at a distance.

[0025] Network 30 can be a serial communication bus in the form of a local area network (LAN). The LAN can include, but is not limited to, a Controller Area Network (CAN), a Controller Area Network with Flexible Data Rates (CAN-FD), Ethernet, Bluetooth, Wi-Fi, and other data formats. Network 30 can be a Wireless Local Area Network (LAN) that links multiple devices using a wireless distribution method, a Wireless Metropolitan Area Network (MAN) that connects several wireless LANs, or a Wireless Wide Area Network (WAN) that covers a large area (such as neighboring towns and cities). Other types of connections can be used.

[0026] Figure 1 The controller C is specifically programmed to execute method 200 (see below for details). Figure 3 (Detailed discussion) and can access information and / or executable programs downloaded from remote sources. References Figure 1 The controller C can be configured to communicate with a remote server 34 and / or a cloud unit 36 ​​via a network 30. The remote server 34 can be a private or public information source maintained by an organization such as, for example, a research institute, company, university, and / or hospital. The cloud unit 36 ​​may include one or more servers hosted on the Internet to store, manage, and process data.

[0027] Now for reference Figure 3 This shows the storage Figure 1On the controller C and can be controlled by Figure 1 The flowchart illustrates method 200 executed by controller C. The start and end of method 200 are indicated by "S" and "E," respectively. Method 200 does not need to be applied in the specific order listed herein. Furthermore, it should be understood that some steps can be omitted.

[0028] Method 200 may begin at block 202, where controller C is programmed to initialize or define one or more initial conditions, including reconstruction parameters for initializing data structures used for 2D and 3D reconstruction of the image or the distribution of the source of interest 16 (see [link to documentation]). Figure 1 Initial conditions may include defining the 2D mesh size, 2D pixel size, 3D mesh size, and 3D voxel size.

[0029] Box 202 includes defining multiple buffers based on initial conditions. Multiple buffers can be defined temporally or spatially. In one embodiment, the initial conditions are time-based, such that each of the multiple buffers is initialized at a predefined start time (t). min,buffer It starts at and ends at a predefined end time (t). max,buffer The end of ) makes t max,buffer =[t min,buffer +Δt]. Here, when the event time (t) event Within a predefined start time and a predefined end time, t is made to... min,buffer ≤t event ≤t max,buffer At that time, individual events fall into the corresponding buffer. Box 202 includes defining the buffer update frequency, which can be defined temporally or spatially. In one example, the buffer update frequency is between approximately 0.5 and 3 seconds.

[0030] In another embodiment, the initial conditions are based on distance, such that each of the plurality of buffers defines a corresponding buffer position (x). buffer y buffer , z buffer Here, when the event location (x) global y global , z global ) and the corresponding buffer position (x buffer y buffer , z buffer When the corresponding distance (d) between the events is less than or equal to the threshold distance (Δd), the individual event falls into the corresponding buffer. In one example, the buffer update frequency can be between approximately 50 and 100 cm.

[0031] Figure 3In each block 204, the controller C is programmed to receive individual events from the radiation data captured by the detector 14. The detector 14 is adapted to transmit time-stamped radiation events consisting of up to N interactions. Each interaction, referred to herein as an "event," is characterized by its event location (x, y, z) and absorbed energy (E) as follows: (x, y, z, E)1, (x, y, z, E)2, ..., (x, y, z, E) N Each individual event is represented by event time (t). event Time stamping is performed. Each of multiple events is marked with its event location or place. Event location can be described based on Cartesian coordinates. Alternatively, it can be based on polar angle (θ) and azimuth angle. To specify the location of the event. The polar angle (θ) is measured from the Z-axis, while the azimuth angle... It is an orthogonal projection of the event location measured from the X-axis (on the XY plane passing through the origin and orthogonal to the Z-axis). Detector 14 can transmit the event stream to controller C in real time.

[0032] Furthermore, detector 14 is suitable for real-time transmission of detector position, referred to herein as the comprehensive detector position, which can be expressed in Cartesian coordinates as (x glob y glob , z glob The initial global position can be chosen to be zero, that is, (x glob y glob , z glob ) = (0, 0, 0). Detector 14 is suitable for real-time transmission of the overall detector attitude (position and orientation), which can be expressed as roll, pitch, and yaw parameters. glob pitch glob yaw glob A set of ).

[0033] Figure 3 In each block 206, controller C is programmed to determine whether one or more predefined criteria are met. Predefined criteria may include the energy of an event being within a specified energy range, i.e., between a minimum energy and a maximum energy. In another example, controller C may process individual events (received in block 204) in real time to determine whether it fits at least one predefined modality. Predefined modalities may include, but are not limited to, Compton imaging, encoded aperture imaging, or attenuation-based imaging. If the predefined criteria are met, then method 200 proceeds to block 208. If not, then method 200 loops back to block 204.

[0034] Figure 3 In each box 208, controller C is programmed to designate one of a plurality of buffers as the current buffer (e.g., Figure 4(Current buffer 318 in the current buffer). Figure 4 An example process is shown for summing and reconstructing multiple events 302 from the current buffer 318 (in two-dimensional space 320) to three-dimensional space 340. Multiple events 302, such as the first volume event 304 and the second (or Nth) volume event 306, are shown in... Figure 4 The diagram is schematically represented as a Compton cone.

[0035] and, Figure 3 In each box 208, controller C is programmed to determine whether an individual event (received in box 204) falls into the current buffer. As mentioned above, if multiple buffers are defined in time, then when the event time (t...) event Within a predefined start time and a predefined end time, t is made to... min,buffer ≤t event ≤t max,buffer When an individual event falls into the current buffer 318, if multiple buffers are defined spatially, then when the event position (x... global y global , z global ) and the corresponding buffer position (x buffer y buffer , z buffer When the corresponding distance (d) between the events is less than or equal to the threshold distance (Δd), the individual event falls into the current buffer. If the individual event (received in box 204) falls into the current buffer, then method 200 proceeds from box 208 to box 210.

[0036] Figure 3 In each box 210, controller C is programmed to correct individual events within the current buffer 318 for pose (position and orientation) and add the individual events to the current buffer 318 in 2D space 320. A comprehensive reference frame is required when reconstructing events from a moving detector 14. Changes in detector pose (recorded as roll, pitch, and yaw) are used to translate individual events to a common comprehensive reference frame. This common comprehensive reference frame allows for the 2D-to-3D reconstruction process described below in box 216.

[0037] refer to Figure 4 Each of the multiple events 302 is individually corrected for the attitude to obtain a corrected event set 308. The multiple events 302 are labeled with corresponding event times. The attitude correction may include obtaining the corresponding detector pitch, corresponding detector yaw angle, and corresponding detector roll of detector 14 at the corresponding event times, and shifting the multiple events 302 in angular space according to the corresponding detector pitch, corresponding detector yaw angle, and corresponding detector roll. (Reference) Figure 4The first individual event 304 and the second (or Nth) individual event 306 are corrected for the pose to obtain the corrected first event 310 and the corrected second (or Nth) event 312, respectively. Method 200 proceeds from box 210 to box 212.

[0038] From box 210, proceed from method 200 to box 212. Figure 3 In each frame 212, controller C is programmed to align multiple events 302 in a common two-dimensional space 320. In some embodiments, the multiple events 302 are moved into a current buffer 318, and then pose correction is performed. In other embodiments, the multiple events 302 are posed-corrected and then moved into the current buffer 318. (See reference...) Figure 4 The current buffer 318 can be determined by the angle (θ). The event 302 is represented by a two-dimensional grid (or a set of pixels). Multiple events 302 can be represented as corresponding Compton cones 322 within the current buffer 318. (See reference...) Figure 4 Aligning multiple events 302 in a common two-dimensional space involves overlapping the corresponding Compton cones 322 together in the current buffer 318 within the two-dimensional space 320. As those skilled in the art will understand, for Compton scattering events, the Compton cones are derived based on the incident scattering angle and the interaction position. The location of the source is determined by projecting the Compton cones onto the image slice in the form of a ring. Other representations may be employed.

[0039] Furthermore, in each box 212, controller C is programmed to record the average spatial coordinates or position (x, y, z) of all individual events (represented by the corresponding Compton cone 322) in the current buffer 318. From box 212, method 200 loops back to box 204, as indicated by line 214. (See reference) Figure 3 If the individual event (received in box 204) does not fall into the current buffer 318, then method 200 proceeds from box 208 to box 216.

[0040] Figure 3 Each frame 216, containing the current buffer 318 containing contributions from multiple events, is added to the 3D space 340 in one step. In other words, multiple events 302 are reconstructed simultaneously in the 3D space 340. The reconstruction in the 3D space 340 is performed once for each of the multiple buffers. The technical advantage here is that the computational burden is much lower compared to calculating the 3D contribution of each event on an event-by-event basis.

[0041] and, Figure 3In each block 216, the controller C is adapted to determine the average overall position 342 of the current buffer 318 by averaging the corresponding event positions of multiple events 302 in the current buffer 318. In other words, the average overall position 342 is calculated using the average spatial coordinates or positions (x, y, z) of all individual events in the current buffer 318.

[0042] refer to Figure 4 A two-dimensional space 320 can be represented by a two-dimensional grid or set of pixels (e.g., by an angle θ, ...). express). Figure 4 It shows the angle (θ1, The first pixel 324 is represented by (θ2, , The second pixel 328 is represented by ). The contribution of each pixel in the current buffer 318 is added to the three-dimensional space 340. The contribution of each pixel can be represented by the number of corresponding Compton cones 322 in the pixel.

[0043] The corresponding contribution from each pixel in the current buffer 318 is projected from the average global position 342 in 3D space 340. 3D space 340 can be represented by 3D voxels. The corresponding angle (θi) between each 3D voxel in 3D space 340 and the average global position 342 is calculated. The corresponding angle (θI, ) is used to look up the corresponding pixel value from the two-dimensional buffer image (current buffer 318), which is in angular space and contains contributions from many events that are added to each corresponding three-dimensional voxel.

[0044] Corresponding angle (θi, ) can be represented by a vector extending from the average full position 342. In one example, with angle (θ1, The first vector 346 extending from the average global position 342 results in the first voxel 344. Due to the angle (θ1, ... The first pixel 324 corresponds to the first pixel 324, so the contribution of the first pixel 324 is added to the first voxel 344 or reconstructed in the first voxel 344.

[0045] In one example, from the average full position 342 at an angle (θ1, The extended first vector 346 results in the first voxel 344. Due to the angle (θ1, Corresponding to the first pixel 324, the contribution of the first pixel 324 is added to the first voxel 344 or reconstructed within the first voxel 344. Figure 4 In the example shown, the first pixel 324 does not include any corresponding Compton cones. In another example, with angle (θ2, The second vector 350, extending from the average overall position 342, results in the second voxel 348. This is due to the angle (θ2, This corresponds to the second pixel 328, therefore the contribution of the second pixel 328 is added to the second voxel 348. The second pixel 328 includes the corresponding Compton cone. The two in the middle. For each angle (θi, Repeat this process. Repeat this process each time the current buffer 318 is filled, gradually filling and creating the 3D image or 3D distribution 352. Method 200 progresses from box 216 to box 218.

[0046] Figure 3 In each block 218, controller C is programmed to retain individual events falling outside the current buffer 318 in memory and reset multiple parameters. Controller C is programmed to zero out the current buffer 318, thereby removing the contribution of older, "stale" events, and subsequently designate another of the multiple buffers as the current buffer 318. In other words, controller C selects a new temporal or spatial boundary for the current buffer 318. The rate at which a new buffer is needed is a function of the input designed in block 202 (i.e., the buffer update frequency). Block 218 includes resetting the list of full 3D event positions (for calculating the average full position 342) so that a new buffer average full position 342 can be obtained.

[0047] Figure 3 In each block 220, controller C is programmed to determine whether a signal indicating the end of method 200 or the process has been received. This signal could be in the form of a predefined measurement time limit indicating completion, or a signal from the user, for example, via an input device (e.g., a mouse or touchscreen button). If no signal is received, method 200 loops from block 220 to block 210. In each block 210, an individual event is added to the current buffer 318. Since the parameters have been reset in block 218, the "current buffer 318" is now a different buffer with different time or space boundaries.

[0048] If a completion signal has been received, then method 200 proceeds from block 220 to block 222, where controller C is programmed to output three-dimensional distribution 352 and method 200 ends.

[0049] Now for reference Figure 2 This illustrates the imaging system 10 (see...) Figure 1The example source localization is shown in the diagram. Imaging device 12 is carried along route 100 from start point 102 to end point 104. Imaging device 12 can be carried by a user or transported on a remotely controlled or autonomous mobile platform or robot (not shown). Figure 1 The controller C is adapted to construct a three-dimensional distribution of one or more sources of interest along route 100. In the example shown, route 100 is within a building 106 with multi-faceted walls 108. (Reference) Figure 2 As the imaging device 12 is transported through the first door 110 and the second door 112 of building 106, the imaging device 12 collects radiation data. The imaging device 12 can stream the radiation data to the controller C in real time and / or record the radiation data. (This is achieved through execution...) Figure 3 Method 200, using radiation data accumulated along route 100, is used to construct a map in three-dimensional space 340. Figure 2 In the example shown, the three-dimensional image or distribution indicates the first source 118 and the second source 120 observed along route 100.

[0050] In summary, the imaging system 10 employs a two-dimensional to three-dimensional approach to minimize the computational burden of creating a three-dimensional image or distribution. Using the current buffer 318 (which contains contributions from many events) within a common two-dimensional space 320 reduces the frequency of three-dimensional reconstruction. The process of reconstructing events in all three dimensions is performed once for each buffer, rather than on an event-by-event basis. Performing three-dimensional reconstruction on many events at once makes the complete three-dimensional reconstruction readily computeable on embedded systems without the necessary memory and processing power.

[0051] The controller C includes computer-readable media (also known as processor-readable media), including any non-transitory (e.g., tangible) medium involved in providing data (e.g., instructions) that can be read by a computer (e.g., by the computer's processor). Such media can take many forms, including but not limited to non-volatile and volatile media. Non-volatile media can include, for example, optical discs or magnetic disks and other persistent storage. Volatile media can include, for example, dynamic random access memory (DRAM), which can constitute main memory. Such instructions can be transmitted via one or more transmission media, including coaxial cables, copper wires, and optical fibers, including wires that include a system bus coupled to the computer's processor. Some forms of computer-readable media include, for example, floppy disks, hard disks, magnetic tape, other magnetic media, CD-ROMs, DVDs, other optical media, other physical media with perforated patterns, RAM, PROMs, EPROMs, FLASH-EEPROMs, any other memory chips or cassette tapes, or any other media that a computer can read.

[0052] The lookup tables, databases, data repositories, or other data stores described in this article can include various mechanisms for storing, accessing, and retrieving a wide range of data, including hierarchical databases, collections of files in a file system, application databases in proprietary formats, relational database management systems (RDBMS), and so on. Each such data store can be contained on a computing device employing a computer operating system such as one of the operating systems mentioned above, and can be accessed via a network in any one or more of various ways. File systems are accessible from the computer operating system and can include files stored in various formats. In addition to languages ​​used for creating, storing, editing, and executing stored sub-procedures (such as PL / SQL mentioned above), RDBMS can also employ Structured Query Language (SQL).

[0053] The flowcharts presented herein illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code, including one or more executable instructions for implementing one or more specific logical functions. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented by a hardware-based device or a combination of purpose-specific hardware and computer instructions for performing a specific function or action. These computer program instructions may also be stored in a computer-readable medium that can instruct a controller or other programmable data processing apparatus to operate in a particular manner, such that the instructions stored in the computer-readable medium produce an article of art including the instructions to implement the specific functions / actions within the flowchart and / or block diagram blocks.

[0054] The numerical values ​​of parameters (e.g., quantities or conditions) in this specification (including the appended claims) should be understood to be modified in each respective instance by the term “about,” regardless of whether “about” actually appears before the numerical value. “About” indicates that the numerical value allows for some slight imprecision (approaching the accuracy of the numerical value in some way; approximately or reasonably close to the numerical value; almost). If the imprecision provided by “about” is not understood in this common sense in the art, then “about” as used herein at least indicates variations that may arise due to common methods of measuring and using such parameters. Furthermore, the disclosure of ranges includes the disclosure of each value as well as ranges further subdivided throughout the range. Each value within the range and the endpoints of the range are disclosed herein as separate embodiments.

[0055] Detailed description and accompanying drawings are provided to support and describe this disclosure, but the scope of this disclosure is defined only by the claims. While some best modes and other embodiments for carrying out the claimed disclosure have been described in detail, various alternative designs and embodiments exist for practicing the disclosure as defined in the appended claims. Furthermore, features of the embodiments shown in the drawings or the various embodiments mentioned in this specification are not necessarily to be construed as independent embodiments. Rather, each feature described in one of the examples of embodiments may be combined with one or more other desired features from other embodiments to produce other embodiments not described in words or with reference to the drawings. Thus, such other embodiments fall within the scope of the appended claims.

Claims

1. An imaging system, comprising: The detector is configured to acquire radiation data from one or more sources, the radiation data including multiple events; A controller, configured to receive the radiation data, has a processor and a tangible non-transitory memory thereon on which instructions are recorded; The execution of the instructions by the processor causes the controller to: Define multiple buffers based on at least one initial condition and designate one of the multiple buffers as the current buffer; Receive an individual event from the plurality of events and determine whether the individual event falls into the current buffer; Each of the plurality of events in the current buffer is corrected for the attitude; Align the plurality of events in the current buffer in two-dimensional space; Reconstruct the plurality of events in the current buffer in three-dimensional space, the reconstruction being performed once for each of the plurality of buffers; as well as A 3D image is created in part based on the reconstruction in the 3D space, wherein correcting the plurality of events within the current buffer includes: The multiple events are time-stamped using the corresponding event times; At the corresponding event time, the corresponding detector pitch, corresponding detector yaw, and corresponding detector roll of the detector are obtained; and In angular space, the plurality of events are moved by the pitch, yaw, and roll of the corresponding detectors.

2. The imaging system of claim 1, wherein after reconstructing the plurality of events in the current buffer in the three-dimensional space, the controller is configured to: Designate another buffer among the plurality of buffers as the current buffer.

3. The imaging system as claimed in claim 1, wherein: The at least one initial condition is time-based, such that the current buffer is within a predefined start time and a predefined end time, and the individual event defines the event time; as well as When the event time is within the predefined start time and the predefined end time, the individual event falls into the current buffer.

4. The imaging system as claimed in claim 1, wherein: The at least one initial condition is based on distance, such that the current buffer defines the corresponding buffer position, and the individual event defines the event position; as well as When the distance between the event location and the corresponding buffer location is less than or equal to a threshold distance, the individual event falls into the current buffer.

5. The imaging system of claim 1, wherein: The at least one initial condition includes the update frequency of the plurality of buffers.

6. The imaging system of claim 5, wherein: The update frequency is between 0.5 and 3 seconds.

7. The imaging system of claim 1, wherein: The detector is configured to be position-sensitive.

8. The imaging system of claim 1, wherein aligning the plurality of events in the two-dimensional space comprises: Represent the plurality of events in the current buffer as corresponding Compton cones; as well as The corresponding Compton cones are overlapped together in the two-dimensional space.

9. The imaging system of claim 1, wherein reconstructing the plurality of events into the three-dimensional space comprises: Determine the average overall position for the current buffer, where the average overall position is the average of the corresponding event positions for the plurality of events in the current buffer.

10. The imaging system of claim 9, wherein reconstructing the plurality of events into the three-dimensional space comprises: The three-dimensional space is represented by three-dimensional voxels; Obtain the corresponding angle between each of the three-dimensional voxels and the average overall position in the three-dimensional space; The corresponding pixel value is obtained from the current buffer based on the corresponding angle, and the corresponding pixel value is represented by the corresponding Compton cone; as well as The corresponding contribution of the pixel value is added to the three-dimensional voxel.

11. A method of operating an imaging system, the imaging system having a detector configured to acquire radiation data and a controller having a processor and a tangible non-transitory memory thereon on which instructions are recorded, the method comprising: The controller defines multiple buffers based on at least one initial condition and designates one of the multiple buffers as the current buffer. The radiation data, which includes multiple events, is received via the controller. The controller determines whether an individual event among the plurality of events falls into the current buffer. Each of the plurality of events in the current buffer is corrected for the attitude; The controller aligns the plurality of events in the current buffer in a two-dimensional space. The controller reconstructs the plurality of events in the current buffer in three-dimensional space, and the reconstruction is performed once for each of the plurality of buffers. as well as A 3D image is created, in part, based on the reconstruction in the 3D space, via the controller. The correction of the multiple events within the current buffer includes: The multiple events are time-stamped using the corresponding event times; At the corresponding event time, the corresponding detector pitch, corresponding detector yaw, and corresponding detector roll of the detector are obtained; and In angular space, the plurality of events are moved by the pitch, yaw, and roll of the corresponding detectors.

12. The method of claim 11, wherein aligning the plurality of events in the two-dimensional space comprises: Represent the plurality of events in the current buffer as corresponding Compton cones; as well as The corresponding Compton cones are overlapped together in the two-dimensional space.

13. The method of claim 11, wherein reconstructing the plurality of events into the three-dimensional space comprises: The three-dimensional space is represented by three-dimensional voxels; Obtain the corresponding angle between each of the three-dimensional voxels and the average global position in the three-dimensional space, wherein the average global position is the average of the corresponding event positions of the plurality of events in the current buffer; The corresponding pixel value is obtained from the current buffer based on the corresponding angle, and the corresponding pixel value is represented by the corresponding Compton cone; as well as The corresponding contribution of the pixel value is added to the three-dimensional voxel.

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