CN116898467A - Cascade imaging system - Google Patents

Abstract

The present invention provides a cascade imaging system comprising: the system comprises a detector module, a cascade photon coincidence module and an image reconstruction module; the detector module comprises two oppositely placed detectors; accommodating an imaged object between the two detectors; the detectors are gamma ray position sensitive detectors, and the two detectors have a time coincidence function; no collimator is arranged; the detector module is used for realizing single photon imaging and data acquisition of cascade gamma photon coincidence imaging; the cascade photon coincidence module is used for determining cascade coincidence gamma photon pairs through a time window; the image reconstruction module is electrically connected with the detector module and the cascade photon coincidence module and is used for completing corresponding image reconstruction based on the data acquired by the detector module. The invention can collect single photon and cascade photon coincidence information at the same time, does not use a collimator, greatly improves the sensitivity of the system and ensures higher image imaging quality.

Description

Cascade imaging system

Technical Field

The invention relates to the technical field of imaging equipment, in particular to a cascade imaging system.

Background

Molecular imaging (molecular imaging) is a science that uses imaging means to display specific molecules at the tissue level, cell and subcellular level, reflect changes in molecular level in the living body, and conduct qualitative and quantitative studies on the biological behavior thereof in terms of images. Therefore, molecular imaging is a product combining molecular biology technology and modern medical imaging, and plays a bridge role in connecting molecular biology and clinical medicine in order to explore occurrence, development and prognosis of diseases and evaluate the curative effect of the medicine.

Among them, positron Emission computed tomography (PositronEmissionTomography, PET) and Single Photon Emission Computed Tomography (SPECT) are collectively referred to as Emission computed tomography (Emission ComputedTomography, ECT) in nuclear medicine. The cascade gamma photon coincidence imaging system uses gamma photons from radionuclide drugs and is therefore also an ECT system which, like PET, requires time coincidence detection, and can also employ collimation techniques in SPECT.

Cascade radiation refers to the fact that when a nuclide decays once, more than two gamma photons with specific energy can be emitted in sequence in a very short time through transition of the energy level from high to low, and compared with traditional single photon imaging, more imaging information can be provided, so that image quality is improved. The gamma photon pairs emitted by the same secondary co-radiation have good correlation among time, position and emission angle, so that the nuclide position information can be directly contained. When the cascade intermediate half-life corresponding to cascade radiation gamma photons is sufficiently small, e.g. less than 10ns, it is very short compared to the movement speed of the radionuclide molecules, and it can be considered that there is no displacement of the radionuclide molecules during this period, i.e. each pair of cascade radiation gamma photons is emitted from the same position. The cascade gamma photon coincidence imaging can directly select to utilize back projection for real-time imaging, thereby avoiding the defect of the traditional nuclear medicine image reconstruction.

SPECT detects gamma photons coming in along a projection line (Ray) through each sensitivity point of the gamma camera probe, the measurement of which represents the sum of the radioactivity of the human body on the projection line. Since radionuclides emit gamma rays in a three-dimensional space in any direction, a collimator is required to accurately detect the spatial position distribution of gamma photons. The gamma rays in a certain angle direction in a certain visual field range enter the crystal through the collimator small hole, and rays which are out of view and are not matched with the collimator hole angle are shielded by the collimator, namely the gamma rays play a role of a space positioning selector.

But the existence of the collimator occupies equipment space and reduces imaging effect. Most of collimators are lead and tungsten, and can absorb gamma photons, so that gamma photons detected by the detector are greatly reduced, the detection efficiency is reduced, and the sensitivity is reduced. Currently, systems employing collimators are commonly used in high resolution SPECT systems, such as sub-millimeter spatial resolution enabled by the most advanced pinhole and collimation systems. However, systems that do not employ collimators can still find important new applications in many molecular imaging applications where ultra-high spatial resolution is not required, such as drug development or screening applications for new imaging agents. Modern clinical studies have found that for a small animal SPECT imaging system, very high sensitivity can be achieved even without the use of a collimator.

The increase in sensitivity may allow faster acquisition of images, allow higher screening application throughput, or observe dynamic processes with very good temporal resolution; and images can be obtained using less radioactive tracers, enabling in vivo imaging of low capacity receptor systems, helping to study new tracer compounds, which have an important role for probes for low yield chemicals or expensive precursors, and enabling reduced costs and regulatory burden of the experiment.

Disclosure of Invention

In view of the above, an object of the present invention is to provide a cascade imaging system, which can greatly improve the sensitivity of the system and can make the imaging quality of the image higher.

In order to solve the technical problems, the invention provides the following technical scheme:

a cascade imaging system comprising: the system comprises a detector module, a cascade photon coincidence module and an image reconstruction module;

the detector module comprises two oppositely placed detectors; accommodating an imaged object between the two detectors; the detectors are gamma ray position sensitive detectors, and the two detectors have a time coincidence function; no collimator is arranged; the detector module is used for realizing single photon imaging and data acquisition of cascade gamma photon coincidence imaging;

the cascade photon coincidence module is used for determining cascade coincidence gamma photon pairs through a time window;

the image reconstruction module is electrically connected with the detector module and the cascade photon coincidence module and is used for completing corresponding image reconstruction based on the data acquired by the detector module.

Preferably, the shape of both of the detectors is any one of a cylinder, an elliptic cylinder, or a rectangle.

Preferably, both of the detectors are attached to the object to be imaged.

Preferably, the detection surfaces of both said detectors completely cover said imaged object.

Preferably, the cascade imaging system adopts a method of combining single photon imaging and cascade gamma photon coincidence imaging to improve the utilization rate of radiopharmaceuticals, obtain more photon information and enable imaging to be more accurate.

Preferably, the image reconstruction module comprises an acquisition unit and a reconstruction unit;

the acquisition unit is used for acquiring a single photon event according to the single photon event information in the acquired data; wherein the single photon event information includes: the energy, location, depth of action, and time of flight of the single photon event; acquiring cascade coincidence photon events according to cascade coincidence photon event information in the acquired data; wherein the cascade coincidence photon event information comprises: cascading conforms to the energy, position, depth of action, time of flight and angle of the photon event;

the reconstruction unit is configured to reconstruct an image from the single photon event and the cascade coincidence photon event.

Preferably, the reconstruction unit adopts a system transmission matrix of analytic calculation or Monte-Card simulation, and performs image reconstruction by combining back projection and iterative reconstruction algorithm.

Preferably, the cascade imaging system further comprises a gantry on which the detector module is mounted;

the frame comprises: the device comprises a mechanical movement assembly, a movement control circuit, a power supply guarantee system, a rack manipulator, a rack movement state display, a scanning bed and a physiological signal detection device.

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

Compared with the prior art, the technical scheme provided by the invention has the following beneficial effects:

the cascade imaging system provided by the invention can collect single photon and cascade photon coincidence information at the same time, and a collimator is not used, so that the sensitivity of the system is greatly improved; images can be obtained faster, allowing higher screening application throughput, observing dynamic processes with very good temporal resolution; and cascade gamma photons are used for coincidence imaging, and more photon information is utilized, so that the imaging quality of the image is higher. The system can obtain images using less radioactive tracers, enables in vivo imaging of low capacity receptor systems, facilitates the study of new tracer compounds, is important for low yield chemical or expensive probe studies, and can reduce the cost of and regulatory burden of the experiment.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a cascade imaging system according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view of a discrete crystal arrangement of a detector module provided by an embodiment of the present invention;

FIGS. 3 (a) -3 (b) are schematic diagrams of imaging processes provided by embodiments of the present invention; wherein A: single photon strikes a crystal of the upper detector; b1 And B2: a pair of cascade coincidence gamma photons respectively strike different root crystals of the upper detector and the lower detector; c: single photons strike a crystal of the lower detector;

fig. 4 (a) -4 (c) are schematic diagrams of cascade gamma photon coincidence imaging reconstruction provided by embodiments of the present invention.

While specific structures and devices are shown in the drawings to enable a clear implementation of embodiments of the invention, this is for illustrative purposes only and is not intended to limit the invention to the specific structures, devices and environments, which may be modified or adapted by those skilled in the art, depending on the specific needs, and which remain within the scope of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. It will be apparent that the described embodiments are some, but not all, embodiments of the invention. All other embodiments, which can be made by a person skilled in the art without creative efforts, based on the described embodiments of the present invention fall within the protection scope of the present invention.

An embodiment of the present invention provides a cascade imaging system, as shown in fig. 1, including a detector module, a cascade photon coincidence module, and an image reconstruction module.

The detector module comprises two oppositely placed detectors, the two detectors can be cylindrical, elliptic cylindrical, rectangular or the like, the two detectors are very close in distance and closely spaced, and an object to be imaged can be just accommodated in the middle distance. In a preferred embodiment, the two detectors are attached to the object being imaged. Further, in the imaging system, the areas of the detection surfaces of the two detectors are close to the size of the detected object, and the object to be imaged is just completely covered.

In the embodiment of the invention, the adopted detector is a gamma ray position sensitive detector, and the two detectors have the time coincidence function. The detector module is a discrete crystal, as shown in fig. 2, and can detect photon energy, position, action depth information (DOI), time of flight information (TOF) and the like, and is used for realizing Single photon imaging (Single-PhotonEmissionComputedTomography, SPECT) and cascade gamma photon coincidence imaging (cascadegammaphotosonic imaging) data acquisition.

The cascade imaging system provided by the invention is not provided with the collimator, so that a great amount of absorption of the collimator to photons is reduced, the detection efficiency is improved, and the system has strong sensitivity.

Further, the cascade photon coincidence module is configured to determine cascade coincidence gamma photon pairs through a time window.

Referring to fig. 3 (a) -3 (b), in data acquisition, a single photon impinges on a crystal of a detector, and the detector performs single photon image reconstruction on received single photon information; a pair of cascade coincidence gamma photons respectively strike different root crystals of the upper detector and the lower detector, and coincidence imaging is carried out on the received cascade coincidence gamma photons. The cascade photon coincidence module utilizes a time window to discriminate cascade coincidence gamma photon pairs for image reconstruction.

Further, the image reconstruction module is electrically connected with the detector module and the cascade photon coincidence module and is used for completing corresponding image reconstruction based on the data acquired by the detector module.

Specifically, the image reconstruction module comprises an acquisition unit and a reconstruction unit;

the acquisition unit is used for acquiring a single photon event according to the single photon event information in the acquired data; wherein the single photon event information includes: the energy, location, depth of action, and time of flight of the single photon event; acquiring cascade coincidence photon events according to cascade coincidence photon event information in the acquired data; wherein the cascade coincidence photon event information comprises: cascading conforms to the energy, position, depth of action, time of flight and angle of the photon event;

the reconstruction unit is used for reconstructing an image from the single photon event and the cascade coincidence photon event. The reconstruction unit adopts a system transmission matrix of analytic calculation or Monte Carlo simulation, and performs image reconstruction by combining back projection and iterative reconstruction algorithm, and the effect is shown in fig. 4 (a) -4 (c).

The cascade imaging system adopts a method of combining single photon imaging and cascade gamma photon coincidence imaging, can improve the utilization rate of radiopharmaceuticals, obtains more photon information, and enables imaging to be more accurate. The cascade coincidence information is used, so that the signal-to-noise ratio of the image is lower, the image effect is better, and the cascade coincidence information is very suitable for imaging research with extremely high sensitivity requirements.

Further, the cascade imaging system further comprises a gantry on which the detector module is mounted; the frame comprises: the device comprises a mechanical movement assembly, a movement control circuit, a power supply guarantee system, a rack manipulator, a rack movement state display, a scanning bed and a physiological signal detection device.

Further, the radiopharmaceuticals used in imaging of 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.

The cascade imaging system of the embodiment is formed by oppositely placing two detectors, the space is compact, the detectors are gamma ray position sensitive detectors, the shape of the detectors can be cylindrical, elliptic cylindrical or rectangular detectors, and the two detector modules have time coincidence functions and perform data acquisition of single photon imaging and cascade coincidence photon imaging; and acquiring single photon event information and cascade coincidence photon event information through an acquisition circuit, and reconstructing an image. The sensitivity of the system is greatly improved due to the fact that no collimator is designed; the cascade coincidence photon imaging technology can obtain richer data information, can obtain higher image quality, and has strong practical value in medicine research.

The above system is further described below in conjunction with application scenarios:

the object to be detected (i.e., the imaged object) is injected with a radiopharmaceutical, which may be a radionuclide-labeled drug (e.g., indium-111, lutetium-177, etc.) that is capable of generating cascade radiation.

Placing an object to be detected on a scanning bed, moving the object to be detected into an imaging visual field, and then carrying out corresponding data acquisition; simultaneously acquiring single photon events and cascade gamma photon coincidence events, and adding time window discrimination of a gamma photon coincidence module for image reconstruction; the acquired events include energy, position, depth of action, time of flight and angle of gamma (gamma) events.

The acquisition unit of the image reconstruction module acquires single photon event information and cascade coincidence photon event information through the acquisition circuit, and the acquired data are subjected to data reconstruction through the reconstruction unit to obtain a corresponding image. The reconstruction unit models the system through Monte Carlo to generate a system transmission matrix, and performs image reconstruction by combining back projection and iterative reconstruction algorithm.

Unlike the prior art that only single photon event imaging is utilized, the system acquires single photon event information and cascade coincidence photon event information through simultaneous acquisition, so that the acquired photon information is more, and a high-quality SPECT image can be acquired. Unlike the collimation of the collimator in the prior art, the detector is tightly attached to the measured object to directly reconstruct an image, and the collimator is not used for absorbing photons, so that the sensitivity of the system is greatly improved. The imaging system of the embodiment has strong practical value in medicine research, and can better assist in disease foundation and life science research.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article or terminal device comprising the element.

References in the specification to "one embodiment," "an example embodiment," "some embodiments," etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the relevant art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

Generally, the terminology may be understood, at least in part, from the use of context. For example, the term "one or more" as used herein may be used to describe any feature, structure, or characteristic in a singular sense, or may be used to describe a combination of features, structures, or characteristics in a plural sense, depending at least in part on the context. In addition, the term "based on" may be understood as not necessarily intended to convey an exclusive set of factors, but may instead, depending at least in part on the context, allow for other factors that are not necessarily explicitly described.

It will be understood that the meanings of "on … …", "over … …" and "over … …" in this disclosure should be interpreted in the broadest sense so that "on … …" means not only "directly on" but also includes meaning "directly on" something with intervening features or layers therebetween, and "over … …" or "over … …" means not only "on" or "over" something, but also may include its meaning "on" or "over" something without intervening features or layers therebetween.

Furthermore, spatially relative terms such as "under …," "under …," "lower," "above …," "upper," and the like may be used herein for ease of description to describe one element or feature's relationship to another element or feature as illustrated in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented and the spatially relative descriptors used herein may similarly be interpreted accordingly.

The invention is intended to cover any alternatives, modifications, equivalents, and variations that fall within the spirit and scope of the invention. In the following description of preferred embodiments of the invention, specific details are set forth in order to provide a thorough understanding of the invention, and the invention will be fully understood to those skilled in the art without such details. In other instances, well-known methods, procedures, flows, components, circuits, and the like have not been described in detail so as not to unnecessarily obscure aspects of the present invention.

Those of ordinary skill in the art will appreciate that all or a portion of the steps in implementing the methods of the embodiments described above may be implemented by a program that instructs associated hardware, and the program may be stored on a computer readable storage medium, such as: ROM/RAM, magnetic disks, optical disks, etc.

The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the invention are intended to be included within the scope of the invention.

Claims (9)

1. A cascade imaging system, comprising: the system comprises a detector module, a cascade photon coincidence module and an image reconstruction module;

the detector module comprises two oppositely placed detectors; accommodating an imaged object between the two detectors; the detectors are gamma ray position sensitive detectors, and the two detectors have a time coincidence function; no collimator is arranged; the detector module is used for realizing single photon imaging and data acquisition of cascade gamma photon coincidence imaging;

the cascade photon coincidence module is used for determining cascade coincidence gamma photon pairs through a time window;

the image reconstruction module is electrically connected with the detector module and the cascade photon coincidence module and is used for completing corresponding image reconstruction based on the data acquired by the detector module.

2. The cascade imaging system of claim 1, wherein the two detectors are any one of cylindrical, elliptical cylindrical, or rectangular in shape.

3. The cascade imaging system of claim 1, wherein two of the detectors are in engagement with an object being imaged.

4. The cascade imaging system of claim 1, wherein detection surfaces of two of the detectors completely cover the imaged object.

5. The cascade imaging system of claim 1, wherein the cascade imaging system employs a combination of single photon imaging and cascade gamma photon coincidence imaging to increase radiopharmaceutical utilization and obtain more photon information for more accurate imaging.

6. The cascade imaging system of claim 1, wherein the image reconstruction module comprises an acquisition unit and a reconstruction unit;

the acquisition unit is used for acquiring a single photon event according to the single photon event information in the acquired data; wherein the single photon event information includes: the energy, location, depth of action, and time of flight of the single photon event; acquiring cascade coincidence photon events according to cascade coincidence photon event information in the acquired data; wherein the cascade coincidence photon event information comprises: cascading conforms to the energy, position, depth of action, time of flight and angle of the photon event;

the reconstruction unit is configured to reconstruct an image from the single photon event and the cascade coincidence photon event.

7. The cascade imaging system of claim 6, wherein the reconstruction unit performs image reconstruction using a system transmission matrix of analytical computation or a monte carlo simulation in combination with a back projection and iterative reconstruction algorithm.

8. The cascade imaging system of claim 1, further comprising a gantry on which the detector module is mounted;

the frame comprises: the device comprises a mechanical movement assembly, a movement control circuit, a power supply guarantee system, a rack manipulator, a rack movement state display, a scanning bed and a physiological signal detection device.

9. The cascade imaging system of claim 1, wherein the radiopharmaceutical used in imaging the cascade imaging system is a nuclear species capable of emitting cascade photons, comprising: lutetium-177, indium-111, iodine-131, copper-6, gallium-67, selenium-75.