A cascaded imaging system

Abstract

The application provides a kind of cascade imaging system, comprising: detector module, cascade photon coincidence module and image reconstruction module;The detector module includes two opposite detectors;Two the object to be imaged is accommodated between the detector;The detector is gamma ray position sensitive detector, two the detector has time coincidence function;Without collimator;The detector module is used to realize single photon imaging and the data acquisition of cascade gamma photon coincidence imaging;The cascade photon coincidence module is used to determine cascade coincidence gamma photon pair by time window;The image reconstruction module is electrically connected with the detector module and the cascade photon coincidence module, for completing corresponding image reconstruction based on the data collected by the detector module.The application can simultaneously collect single photon and cascade photon coincidence information, without using collimator, greatly improving the sensitivity of the system, so that the image imaging quality is higher.

Description

Technical Field

[0001] This invention relates to the field of imaging equipment technology, and in particular to a cascaded imaging system. Background Technology

[0002] Molecular imaging is the science that uses imaging techniques to visualize specific molecules at the tissue, cellular, and subcellular levels, reflecting changes at the molecular level in vivo, and conducting qualitative and quantitative studies on their biological behavior through imaging. Therefore, molecular imaging is a product of combining molecular biology techniques with modern medical imaging, serving as a bridge between molecular biology and clinical medicine in exploring the occurrence, development, and outcome of diseases and evaluating drug efficacy.

[0003] Positron emission tomography (PET) and single-photon emission computed tomography (SPECT) are collectively referred to as emission computed tomography (ECT) in nuclear medicine. Cascaded gamma-photon coincidence imaging systems use gamma photons from radiopharmaceuticals, and are therefore also a type of ECT system. Like PET, they require time coincidence detection, and can also employ the collimation techniques used in SPECT.

[0004] Cascade radiation refers to the emission of two or more gamma photons of specific energies in a very short time during a single decay of a nuclide, through energy level transitions from high to low. Compared to traditional single-photon imaging, this provides more imaging information, thus improving image quality. The pairs of gamma photons emitted in the same cascade radiation exhibit strong correlations in time, position, and emission angle, directly containing nuclide position information. When the half-life of the cascade intermediate state corresponding to the gamma photons is sufficiently short, such as less than 10 ns, it is extremely short compared to the movement speed of the radioactive nuclide molecule. It can be assumed that the nuclide molecule has no displacement during this time, meaning that each pair of cascade radiation gamma photons is emitted from the same location. Cascade gamma photon coincidence imaging can directly utilize backprojection for real-time imaging, thus avoiding the shortcomings of traditional nuclear medicine image reconstruction.

[0005] SPECT detects gamma photons entering along a projection line (ray) at each sensitive point of the gamma camera probe. The measured value represents the sum of radioactivity emitted by the human body along that projection line. Since radioactive nuclides emit gamma rays in all directions in three-dimensional space, a collimator is needed to accurately detect the spatial distribution of gamma photons. Installed on the outermost layer of the probe, its function is to allow gamma rays within a certain angle and field of view to pass through the collimator aperture into the crystal, while rays outside the field of view that do not match the collimator aperture angle are shielded by the collimator, thus acting as a spatial positioning selector.

[0006] However, the presence of a collimator occupies equipment space and reduces imaging quality. Collimator materials are often lead or tungsten, which absorb gamma photons, significantly reducing the number of gamma photons detected by the detector, thus lowering detection efficiency and sensitivity. Currently, systems using collimators are typically used in high-resolution SPECT systems, such as those achieving sub-millimeter spatial resolution with state-of-the-art pinhole and collimation systems. However, systems without collimators can still find important new applications in many molecular imaging applications that do not require ultra-high spatial resolution, such as drug development or screening for new imaging agents. Modern clinical research has found that very high sensitivity can be achieved even without a collimator in a small animal SPECT imaging system.

[0007] Increased sensitivity allows for faster image acquisition, enabling higher throughput for screening applications or observation of dynamic processes at very high temporal resolution; and it allows for image acquisition with less radioactive tracers, enabling in vivo imaging of low-volume receptor systems, which is helpful for studying new tracer compounds. This is of great importance for probes of low-yield chemicals or expensive precursors, and can reduce experimental costs and alleviate the regulatory burden of experiments. Summary of the Invention

[0008] In view of this, the purpose of the present invention is to provide a cascaded imaging system that can greatly improve system sensitivity and enable higher image quality.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0010] A cascaded imaging system includes: a detector module, a cascaded photon coincidence module, and an image reconstruction module;

[0011] The detector module includes two detectors placed opposite each other; the object to be imaged is accommodated between the two detectors; the detectors are gamma-ray position-sensitive detectors, and the two detectors have a time coincidence function; no collimator is provided; the detector module is used to realize data acquisition for single-photon imaging and cascaded gamma-photon coincidence imaging.

[0012] The cascaded photon matching module is used to determine cascaded matching gamma photon pairs through a time window;

[0013] The image reconstruction module is electrically connected to the detector module and the cascaded photonic coincidence module, and is used to complete the corresponding image reconstruction based on the data collected by the detector module.

[0014] Preferably, the two detectors are cylindrical, elliptical cylindrical, or rectangular in shape.

[0015] Preferably, the two detectors are in contact with the object being imaged.

[0016] Preferably, the detection surfaces of the two detectors completely cover the object being imaged.

[0017] Preferably, the cascaded imaging system employs a combination of single-photon imaging and cascaded gamma photon coincidence imaging to improve the utilization rate of radiopharmaceuticals, obtain more photon information, and make the imaging more accurate.

[0018] Preferably, the image reconstruction module includes an acquisition unit and a reconstruction unit;

[0019] The acquisition unit is used to acquire single-photon events based on single-photon event information in the acquired data; wherein, the single-photon event information includes: the energy, position, depth of action, and flight time of the single-photon event; and to acquire cascaded coincident photon events based on cascaded coincident photon event information in the acquired data; wherein, the cascaded coincident photon event information includes: the energy, position, depth of action, flight time, and angle of the cascaded coincident photon event;

[0020] The reconstruction unit is used to reconstruct the image based on the single-photon event and the cascaded coincident photon event.

[0021] Preferably, the reconstruction unit uses an analytical calculation or Monte Carlo simulation of the system transfer matrix, combined with back projection and iterative reconstruction algorithms to reconstruct the image.

[0022] Preferably, the cascaded imaging system further includes a frame, on which the detector module is mounted;

[0023] The rack includes: mechanical motion components, motion control circuit, power supply system, rack manipulator, rack motion status display, scanning bed, and physiological signal detection device.

[0024] Preferably, the radiopharmaceutical used in the cascade imaging system is a nuclide capable of emitting cascade photons, including but not limited to: lutetium-177, indium-111, iodine-131, copper-6, gallium-67, and selenium-75.

[0025] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0026] The cascaded imaging system provided by this invention can simultaneously acquire single-photon and cascaded photon coincidence information without the use of a collimator, greatly improving the system's sensitivity. It allows for faster image acquisition, enabling higher throughput for screening applications and observation of dynamic processes with excellent temporal resolution. Furthermore, the use of cascaded gamma photon coincidence imaging utilizes more photon information, resulting in higher image quality. This system can acquire images using less radioactive tracers, enabling in vivo imaging of low-volume receptor systems. This is crucial for studying new tracer compounds, particularly those requiring low-yield chemicals or expensive probes, and can reduce experimental costs and regulatory burden. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the structure of the cascaded imaging system provided in an embodiment of the present invention;

[0029] Figure 2 This is a cross-sectional view of the discrete crystal arrangement of the detector module provided in an embodiment of the present invention;

[0030] Figures 3(a)-3(b) This is a schematic diagram of the imaging process provided in an embodiment of the present invention; wherein A: a single photon strikes one crystal of the upper detector; B1, B2: a pair of cascaded coincident gamma photons strike different root crystals of the upper and lower detectors respectively; C: a single photon strikes one crystal of the lower detector;

[0031] Figures 4(a)-4(c) This is a schematic diagram of cascaded gamma photon coincidence imaging reconstruction provided in an embodiment of the present invention.

[0032] As shown in the figure, specific structures and devices are marked in the figure to clearly illustrate the structure of the embodiments of the present invention. However, this is only for illustrative purposes and is not intended to limit the present invention to the specific structure, device and environment. According to specific needs, those skilled in the art can adjust or modify these devices and environments, and such adjustments or modifications are still included in the protection scope of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] Embodiments of the present invention provide a cascaded imaging system, such as Figure 1 As shown, the cascaded imaging system includes a detector module, a cascaded photon coincidence module, and an image reconstruction module.

[0035] The detector module includes two detectors placed opposite each other. The detectors can be cylindrical, elliptical, or rectangular, etc., and are very close together, with a spacing just large enough to accommodate the object being imaged. In a preferred embodiment, the two detectors are in close contact with the object being imaged. Furthermore, in the imaging system, the area of ​​the detection surfaces of the two detectors is close to the size of the object being imaged, completely covering it.

[0036] In this embodiment of the invention, a gamma-ray position-sensitive detector is used, and the two detectors have time synchronization functionality. The detector module is a discrete crystal, such as... Figure 2 As shown, it can detect photon energy, position, depth of action (DOI) information, and time of flight (TOF) information, and is used to realize data acquisition for single-photon emission computed tomography (SPECT) and cascade gamma photon coincidence imaging.

[0037] The cascaded imaging system provided by this invention does not have a collimator, thereby reducing the large amount of photon absorption by the collimator, improving detection efficiency, and giving the system a high sensitivity.

[0038] Furthermore, the cascaded photon coincidence module is used to determine cascaded coincident gamma photon pairs through a time window.

[0039] refer to Figures 3(a)-3(b) As shown, during data acquisition, a single photon strikes one crystal of a detector, which then performs single-photon image reconstruction based on the received single-photon information. A pair of cascaded coincident gamma photons strikes different crystals of the upper and lower detectors, respectively, and the received cascaded coincident gamma photons are used for coincidence imaging. The cascaded photon coincidence module uses a time window to identify the cascaded coincident gamma photon pairs for image reconstruction.

[0040] Furthermore, the image reconstruction module is electrically connected to the detector module and the cascaded photonic coincidence module, and is used to complete the corresponding image reconstruction based on the data collected by the detector module.

[0041] Specifically, the image reconstruction module includes an acquisition unit and a reconstruction unit;

[0042] The acquisition unit is used to acquire single-photon events based on single-photon event information in the acquired data; wherein, the single-photon event information includes: the energy, position, depth of action, and time of flight of the single-photon event; and to acquire cascaded coincident photon events based on cascaded coincident photon event information in the acquired data; wherein, the cascaded coincident photon event information includes: the energy, position, depth of action, time of flight, and angle of the cascaded coincident photon event;

[0043] The reconstruction unit is used to reconstruct images based on single-photon events and cascaded coincident photon events. The reconstruction unit employs analytical calculation or Monte Carlo simulation of the system transfer matrix, combined with back-projection and iterative reconstruction algorithms, to perform image reconstruction, achieving results such as... Figures 4(a)-4(c) As shown.

[0044] The cascaded imaging system described in this invention combines single-photon imaging with cascaded gamma photon coincidence imaging, which improves the utilization rate of radiopharmaceuticals, obtains more photon information, and makes imaging more accurate. The use of cascaded coincidence information results in a lower signal-to-noise ratio and better image quality, making it highly suitable for imaging research with extremely high sensitivity requirements.

[0045] Furthermore, the cascaded imaging system also includes a gantry, on which the detector module is mounted; the gantry includes: mechanical motion components, motion control circuitry, power supply system, gantry manipulator, gantry motion status display, scanning bed, and physiological signal detection device.

[0046] Furthermore, the radiopharmaceuticals used in the cascade imaging system are nuclides capable of emitting cascade photons, including but not limited to: lutetium-177, indium-111, iodine-131, copper-6, gallium-67, selenium-75, etc.

[0047] The cascaded imaging system in this embodiment consists of two detectors placed opposite each other with a compact spacing. The detectors are gamma-ray position-sensitive detectors, and their shapes can be cylindrical, elliptical, or rectangular. The two detector modules have time-synchronization capabilities, enabling data acquisition for both single-photon imaging and cascaded coincident photon imaging. Single-photon event information and cascaded coincident photon event information are obtained through the acquisition circuit, and image reconstruction is performed. The absence of a collimator significantly improves the system's sensitivity. Cascaded coincident photon imaging technology can obtain richer data information and achieve higher image quality, making it highly valuable for drug research.

[0048] The following section will provide a further explanation of the above system in the context of application scenarios:

[0049] The object to be detected (i.e. the object being imaged) is injected with a radiopharmaceutical, which can be a radionuclide-labeled drug (such as indium-111, lutetium-177, etc.) capable of producing cascade radiation.

[0050] The object to be detected is placed on the scanning bed, moved into the imaging field of view, and then the corresponding data is acquired. At the same time, single-photon events and cascaded gamma photon coincidence events are acquired, and the time window discrimination of the gamma photon coincidence module is added for image reconstruction. The acquired events include the energy, position, depth of action, flight time and angle of the gamma event.

[0051] The image reconstruction module's acquisition unit collects single-photon event information and cascaded coincident photon event information through acquisition circuits. The acquired data is then reconstructed by the reconstruction unit to obtain the corresponding image. The reconstruction unit models the system using Monte Carlo methods to generate a system transport matrix, and then performs image reconstruction using back-projection and iterative reconstruction algorithms.

[0052] Unlike existing technologies that only utilize single-photon event imaging, this system simultaneously acquires single-photon event information and cascaded coincident photon event information, resulting in a greater amount of photon information and thus obtaining high-quality SPECT images. Unlike existing technologies that use collimators for collimation, this system performs image reconstruction directly with the object under test, eliminating the need for a collimator to absorb photons and significantly increasing system sensitivity. This imaging system has strong practical value in drug research and can better support basic disease and life science research.

[0053] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0054] The use of terms such as "an embodiment," "an embodiment," "an exemplary embodiment," and "some embodiments" in the specification indicates that the described embodiment may include a specific feature, structure, or characteristic, but not every embodiment necessarily includes that specific feature, structure, or characteristic. Furthermore, when a specific feature, structure, or characteristic is described in connection with an embodiment, implementing such a feature, structure, or characteristic in conjunction with other embodiments (whether explicitly described or not) should be within the knowledge of those skilled in the art.

[0055] Generally, terms can be understood at least partly from their use in context. For example, depending at least partly on the context, the term "one or more" as used herein can be used to describe any feature, structure, or characteristic in a singular sense, or a combination of features, structures, or characteristics in a plural sense. Additionally, the term "based on" can be understood not necessarily to convey an exclusive set of factors, but rather, alternatively, depending at least partly on the context, to allow for the presence of other factors that are not necessarily explicitly described.

[0056] It is understood that the meanings of “on”, “above” and “above” in this disclosure should be interpreted in the broadest sense, such that “on” means not only “directly on” something, but also includes something with an intermediary feature or layer, and that “above” or “above” means not only “on” something, but also includes something “above” or “above” without an intermediary feature or layer.

[0057] Furthermore, spatially related terms such as “below,” “under,” “lower,” “above,” and “upper” are used herein for convenience to describe the relationship of one element or feature to one or more other elements or features, as illustrated in the accompanying drawings. Spatially related terms are intended to cover different orientations in the use or operation of the device other than those depicted in the accompanying drawings. The device may be oriented in other ways, and the spatially related descriptive terms used herein can be interpreted similarly.

[0058] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. To provide the public with a thorough understanding of this invention, specific details are described in detail in the following preferred embodiments; however, those skilled in the art will fully understand the invention even without these details. Furthermore, to avoid unnecessary misunderstanding of the essence of this invention, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0059] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A cascaded imaging system, characterized in that, include: Detector module, cascaded photon coincidence module and image reconstruction module; The detector module includes two detectors placed opposite each other; The object to be imaged is accommodated between the two detectors, and the two detectors are in contact with the object being imaged; the detectors are gamma-ray position-sensitive detectors, and the two detectors have a time coincidence function; no collimator is provided; the detector module is used to realize data acquisition for single-photon imaging and cascaded gamma-photon coincidence imaging. The cascaded photon matching module is used to determine cascaded matching gamma photon pairs through a time window; The image reconstruction module is electrically connected to the detector module and the cascaded photonic coincidence module, and is used to complete the corresponding image reconstruction based on the data collected by the detector module; The image reconstruction module includes an acquisition unit and a reconstruction unit; The acquisition unit is used to acquire single-photon events based on single-photon event information in the acquired data; wherein, the single-photon event information includes: energy, position, depth of action, and time of flight of the single-photon event; and to acquire cascaded coincident photon events based on cascaded coincident photon event information in the acquired data; wherein, the cascaded coincident photon event information includes: energy, position, depth of action, time of flight, and angle of the cascaded coincident photon event; the reconstruction unit is used to reconstruct an image based on the single-photon events and the cascaded coincident photon events.

2. The cascaded imaging system according to claim 1, characterized in that, The two detectors can be cylindrical, elliptical cylindrical, or rectangular in shape.

3. The cascaded imaging system according to claim 1, characterized in that, The detection surfaces of the two detectors completely cover the imaged object.

4. The cascaded imaging system according to claim 1, characterized in that, The cascaded imaging system employs a combination of single-photon imaging and cascaded gamma photon coincidence imaging to improve the utilization rate of radiopharmaceuticals, obtain more photon information, and make imaging more accurate.

5. The cascaded imaging system according to claim 1, characterized in that, The reconstruction unit uses analytical calculation or Monte Carlo simulation of the system transfer matrix, combined with back projection and iterative reconstruction algorithms to reconstruct the image.

6. The cascaded imaging system according to claim 1, characterized in that, The cascaded imaging system also includes a frame, on which the detector module is mounted; The rack includes: mechanical motion components, motion control circuit, power supply system, rack manipulator, rack motion status display, scanning bed, and physiological signal detection device.

7. The cascaded imaging system according to claim 1, characterized in that, The radiopharmaceuticals used in the cascade imaging system are nuclides capable of emitting cascade photons, including: lutetium-177, indium-111, iodine-131, copper-6, gallium-67, and selenium-75.

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