Gamma camera imaging method and gamma camera imaging device

Abstract

This presentation provides a gamma camera imaging method and a gamma camera imaging device. The method comprises: the selection (S101), from energy spectra captured by a gamma camera on one or more radioactive materials, of one or more energy domains of each radioactive material as one or more monitored energy regions of the radioactive material; the implementation (S102) of image reconstruction on the monitored energy regions of each radioactive material; the implementation (S103) of normalization on images obtained via image reconstruction; and the implementation (S104) of overlaying the normalized images to form a composite image. Figure 3

Description

Title of the invention: Gamma camera imaging method and gamma camera imaging device Technical field

[0001] The present application relates to the technical field of gamma cameras, in particular a gamma camera imaging method and a gamma camera imaging device. Background

[0002] A gamma camera is used primarily in the field of nuclear security and testing to take a dynamic or static image of a radiation field of an area of ​​contamination by radioactive material, and the resulting image is used in combination with an image resulting from an optical imaging method to obtain information on the distribution of the radioactive material.

[0003] An existing gamma camera generally uses a linear data processing method, which does not distinguish between the received signals and performs projection image restoration and original image reconstruction using all effective energy signal bands. After image reconstruction, statistical fluctuations and shadows often appear in the background of bright spots due to quantization losses and approximation processes during data processing. Then, an image area screening method is used, using a brightness threshold or a significance threshold to select only some of the image areas having more obvious images to be used in combination with optical images. Summary

[0004] According to one aspect of the present application, there is provided a method of gamma camera imaging comprising: selecting, from energy spectra captured by a gamma camera on one or more radioactive materials, one or more energy domains of each of the one or more radioactive materials as one or more monitored energy regions of the radioactive material; performing image reconstruction on the monitored energy regions of each of the one or more radioactive materials; performing normalization on images obtained via the image reconstruction; and performing superposition on the normalized images to form a composite image.

[0005] In some embodiments, the selection comprises: scanning energy spectra to find peaks and comparing the peaks with the branch energies of respective radioactive materials recorded in a predetermined nuclide library to determine the one or more radioactive materials; determining, for each of the one or more radioactive materials, a portion of the branches of the radioactive material having a relatively higher branch ratio, or lower energy, as one or more branches of the radioactive material to be monitored; and determining, for each of the one or more branches of the radioactive material, an energy domain centered on the central energy of the branch and having the width of a half-maximum width of a peak corresponding to the branch, as one of the one or more monitored energy regions of the radioactive materials.

[0006] In some embodiments, the gamma camera imaging method further comprises: determining, for each of the images obtained via the image reconstruction, whether there is a closed region in the image; and adaptively adjusting, in the case where there is a closed region in the image and if the ratio of the contrast of the closed region to the contrast of a background region outside the closed region is less than a predetermined threshold, energy domains of the monitored energy regions corresponding to the image.

[0007] In some embodiments, adaptive adjustment comprises: gradually expanding or contracting an energy region to be adjusted in a predetermined energy step, until the ratio of the contrast of the gated area to the contrast of a background area outside the gated area reaches the predetermined threshold.

[0008] In some embodiments, the gamma camera imaging method further comprises: rejecting, in the event that there is not a closed region in the image, the energy domains of the monitored energy regions corresponding to the image.

[0009] In some embodiments, the gamma camera imaging method further comprises: discarding, in the event that there is not a closed region in the image, energy domains of the monitored energy regions corresponding to the image after a predetermined period of time.

[0010] According to another aspect of the present application, there is provided a gamma camera imaging device, comprising: a selection module configured to select, from energy spectra captured by a gamma camera on one or more radioactive materials, one or more energy domains of each radioactive material from the one or more radioactive materials, as one or more monitored energy regions of the radioactive material; a image reconstruction configured to perform image reconstruction on the monitored energy regions of each of the one or more radioactive materials; a normalization module configured to perform normalization on images obtained via the image reconstruction; and a superposition module configured to perform superposition on the normalized images to form a composite image.

[0011] In some embodiments, the selection module comprises: a peak discovery module configured to scan the energy spectra to find peaks, and compare the peaks with the branch energies of respective radioactive materials recorded in a predetermined nuclide library to determine the one or more radioactive materials; a branch determination module configured to determine, for each radioactive material of the one or more radioactive materials, a portion of the branches of the radioactive material having a relatively higher branch ratio, or lower energy, as one or more branches of the radioactive material to be monitored;and an energy domain determination module configured to determine, for each branch of the one or more branches of the radioactive material, an energy domain centered on the central energy of the branch and having the width of a half-maximum width of a peak corresponding to the branch, as one of the one or more monitored energy regions of the radioactive materials.;

[0012] In some embodiments, the image reconstruction module comprises: a closed region determination module configured to determine, for each of the images obtained through the image reconstruction, whether or not there is a closed area in the image; and an energy region adjustment module configured to adaptively adjust, in the case where there is a closed region in the image and if the ratio of the contrast of the closed area to the contrast of a background area outside the closed area is less than a predetermined threshold, the energy domains of the monitored energy regions corresponding to the image.

[0013] In some embodiments, the energy region adjustment module is further configured to gradually expand or contract an energy region to be adjusted in a predetermined energy step, until the ratio of the contrast of the enclosed area to the contrast of a background area outside the enclosed area reaches the predetermined threshold.

[0014] In some embodiments, the image reconstruction module further comprises: a rejection module configured to reject, in the case where there is not a closed region in the image, the energy domains of the monitored energy regions corresponding to the image. In some embodiments, the image reconstruction module further comprises: a rejection module configured to reject, in the case where there is no closed region in the image, the energy domains of the monitored energy regions corresponding to the image after a predetermined period of time.

[0015] According to another aspect of the present application, there is provided a gamma camera imaging device, comprising: instructions for storing in memory; a processor configured to execute the instructions stored in the memory to implement the gamma camera imaging method as discussed above.

[0016] According to another aspect of the present application, there is provided a computer-readable storage medium, storage instructions, which are executable by a processor to implement the gamma camera imaging method as discussed above.

[0017] According to another aspect of the present application, there is provided a gamma camera, comprising the gamma camera imaging device as discussed above.

[0018] According to the gamma camera imaging method and the gamma camera imaging device in the present application, each monitored energy region of each radioactive material is analyzed separately, thereby taking all the radioactive materials into account, and thus the background noise can be reduced and the signal-to-noise ratio can be improved. Furthermore, according to the gamma camera imaging method and the gamma camera imaging device in the present application, only the projected images of moving radioactive materials need to be refreshed in the dynamic measurement mode, so that the imaging of the moving materials and the imaging of the stationary materials do not affect each other. Brief description of the drawings

[0019] The features and advantages of the present application will be more clearly understood with reference to the accompanying drawings. The drawings are schematic and should not be construed as imposing any limitation on the present application. In the drawings:

[0020] [Fig.l] [Fig.l] shows a diagram of an energy spectrum captured by a gamma camera from three radioactive sources (Am241, Co57 and Bal33);

[0021] [Fig.2] [Fig.2] shows a diagram of an example image obtained by image reconstruction by means of a gamma camera using a conventional method from the energy spectrum of the three radioactive sources (Am241, Co57 and Bal33) of [Fig.l];

[0022] [Fig.3] [Fig.3] shows a flowchart of a camera imaging method gamma according to an embodiment of the present application;

[0023] [Fig.4] [Fig.4] shows a diagram of an energy spectrum captured by a gamma camera from three radioactive sources (Am241, Co57 and Bal33);

[0024] [Fig.5] [Fig.5] shows a diagram of a result image obtained by image reconstruction by means of a gamma camera using the gamma camera imaging method according to an embodiment of the present application from the three radioactive sources (Am241, Co57 and Bal33) of [Fig.4];

[0025] [Fig.6] [Fig.6] shows a diagram of an energy spectrum captured by a gamma camera from high-energy radioactive material (e.g. Co60);

[0026] [Fig.7] [Fig.7] shows a comparison diagram of a result image obtained by image reconstruction by means of a gamma camera using a conventional method from two radioactive sources (Am241 and Co57) and a result image obtained by image reconstruction by means of a gamma camera using the gamma camera imaging method according to an embodiment of the present application from the same radioactive sources;

[0027] [Fig.8] [Fig.8] shows a block diagram of a gamma camera imaging device according to one embodiment of the present application; and

[0028] [Fig.9] [Fig.9] shows an example block diagram of a computing device which is applicable to the implementation of a gamma camera imaging device according to an embodiment of the present application. Detailed description

[0029] The monitored result of a gamma camera is presented in the form of an image that the human eye observes to determine the types of radioactive materials and their distribution, and therefore the extent to which the radioactive materials can be imaged is a key factor affecting the monitored result of the gamma camera. A fundamental requirement of imaging is that a certain number of gamma events emitted by radiation sources and statistically observed exceeds the number of gamma events in an ambient environment by a certain proportion, i.e., an ideal analysis result can be obtained by statistical and image processing methods only when the signal-to-noise ratio reaches a certain threshold.

[0030] In actual application, it is difficult to obtain a specified signal-to-noise ratio. The reason is that the detection efficiency of high-energy particles is not high enough due to limitations in size and materials of the detectors, and there is a considerable amount of ambient background noise in the background for low-energy particles. Therefore, a conventional gamma camera generally does not have a sufficiently long detection time and requires a relatively long measurement time.

[0031] [Fig.l] shows a diagram of an energy spectrum captured by a gamma camera from three radioactive sources (Am241, Co57, and Bal33). [Fig.l] is represented by Figures 1(a) and 1(b), where the horizontal axis represents the energy, in terms of channel value, and the vertical axis represents the count value. In [Fig.l](a), the energy spectrum region generated by Am241 is marked by a solid line, the energy spectrum region generated by Co57 is marked by a dotted line, and the energy spectrum region generated by Bal33 is marked by a dashed line. In [Fig.l](b), the light gray area provides valid information, while the dark gray area provides noise information (in the example, global energy peaks are used instead of flat Compton scattering data as valid information for imaging).For gamma camera data processing, the gamma camera can provide better imaging only when the ratio of the area of ​​the light gray region to the area of ​​the dark gray region reaches a certain value.

[0032] In the case of imaging, the brightness of bright spots formed by respective radioactive spot sources in the reconstructed image is very different if there is a large difference in strength and weakness of the radioactive materials. A bright spot of a weaker radioactive source is easily submerged in a statistically fluctuating background formed by a stronger radioactive source. Since the brightness value of the bright spot of the weaker radioactive source hardly exceeds the selection threshold, the bright spot of the weaker radioactive source will not be selected for use in combination with optical images or, even if it is, its brightness is very weak and difficult to observe by the human eye.

[0033] [Fig. 2] shows a diagram of an example image obtained by image reconstruction by means of a gamma camera using a conventional method from the energy spectrum of the three radioactive sources (Am241, Co57 and Bal33) of [Fig. 1]. In [Fig. 2], the horizontal axis and the vertical axis respectively represent the pixel scales of a result image of a gamma camera. In this image, only the bright spots represented by the two peaks of Am241 in the energy spectrum, and not Co57 and Bal33, can be observed. As a result, conventional methods fail to adequately represent the information from all radioactive sources.

[0034] According to the embodiment of the present application, there is provided a gamma camera imaging method and device, which can fully utilize the effective information of each radioactive source, with an optimized display of the distribution of radioactive materials in the field of view.

[0035] [Fig. 3] shows a flowchart of a gamma camera imaging method according to one embodiment of the present application. As shown in [Fig. 3], the Gamma camera imaging method 100 according to one embodiment of the present application comprises S101-S104.

[0036] In step S101, from the energy spectra captured by a gamma camera on one or more radioactive materials, one or more energy domains of each radioactive material among the one or more radioactive materials are selected as one or more monitored energy regions of the radioactive material.

[0037] For step S101, in some embodiments, selecting the monitored energy regions may include: scanning the energy spectra to find peaks and comparing the peaks with the branch energies of respective radioactive materials recorded in a predetermined nuclide library to determine the one or more radioactive materials; determining, for each radioactive material among the one or more radioactive materials, a portion of the branches of the radioactive material having a relatively higher branch ratio, or lower energy, as one or more branches of the radioactive material to be monitored;and determining, for each branch of the one or more branches of the radioactive material, an energy domain centered on the central energy of the branch and having the width of a half-maximum width of a peak corresponding to the branch, as one of the one or more monitored energy regions of the radioactive materials.;

[0038] It should be understood that, for a given radioactive material, a given monitored energy region may be selected, or multiple monitored energy regions may be selected, and for different radioactive materials, their monitored energy regions may overlap each other. Moreover, with respect to determining the branches of each radioactive material, two criteria (namely, branching ratio and energy) are mainly considered. The reason for this is that the detectors of the gamma camera have a lower efficiency of detecting high-energy gamma particles, and therefore it is better to select a branch with lower energies; and the higher the branching ratio, the more gamma particles the same amount of radioactive material produces, and therefore it is better to select a branch with a higher branching ratio.It should be understood that the terms "lower" and "upper," as used herein, are terms referring to various branches of the radioactive material.

[0039] In step S102, image reconstruction is performed on the monitored energy regions of each of the one or more radioactive materials.

[0040] For step S102, for image reconstruction, it is possible to use as needed a commonly used decoding method or a statistical decoding method.

[0041] In some embodiments, the gamma camera imaging method according to the present application may further comprise: determining, for each of the images obtained via the image reconstruction, whether there is a closed area in the image; and adaptively adjusting, in the case where there is a closed region in the image and the ratio of the contrast of the closed area to the contrast of a background area outside the closed area is less than a predetermined threshold, energy domains of the monitored energy regions corresponding to the image. In some embodiments, the adaptive adjustment may comprise: gradually expanding or reducing an energy region to be adjusted in a predetermined energy step, until the ratio of the contrast of the closed area to the contrast of a background area outside the closed area reaches the predetermined threshold.The energy range to be adaptively adjusted is determined by the definition of the detectors and the distance between adjacent peaks. In general, if the energy calibration of the gamma camera is relatively accurate, the degree of adaptive adjustment is not too great, e.g., a range of 2 to 5 full widths at half maximum can usually be selected.

[0042] The gamma camera may operate in a static measurement mode and a dynamic measurement mode. In the static measurement mode, the method according to the present application may further comprise: rejecting, in the case where there is not a closed region in the image, the energy domains of the monitored energy regions corresponding to the image. Alternatively, in the dynamic measurement mode, the method according to the present application may further comprise: rejecting, in the case where there is not a closed region in the image, the energy domains of the monitored energy regions corresponding to the image after a predetermined period of time. In the dynamic measurement mode, the dynamic movement of the radioactive materials may cause the appearance of a closed area in the reconstructed image, so that the data rejection is performed after a predetermined period of time of continuous observation.By discarding data from a monitored energy region that cannot be imaged, not only can the amount of computation be reduced, but also the influence of background noise can be reduced.

[0043] In step S103, the images obtained through image reconstruction are normalized. For step S103, in the normalization, a pixel value is normalized from a range of maximum and minimum values ​​to a range of zero to one. The images are normalized to a same maximum value, which equally amplifies an image of a weak source.

[0044] In step S104, the normalized images are superimposed to form a composite image. For step S104, the image superposition may employ different color channels to clearly present the distribution of the respective radioactive materials.

[0045] According to the gamma camera imaging method according to one embodiment of the present application, the data of each monitored energy region is analyzed separately, and then other information outside the energy region is excluded, so that only the background events in the energy region constitute noise, which is greatly reduced compared to the overall background, and thus the method can effectively improve the signal-to-noise ratio. Furthermore, another advantage of the gamma camera imaging method according to the embodiment of the present application in which each monitored energy region is analyzed separately is that, when the movement of a radioactive material is detected in real time in a dynamic mode, only the projected image of the monitored energy region of the radioactive material can be erased for refreshing, without erasing the other monitored energy regions.Thus, for the same monitored energy regions, the imaging of the moving and stationary material does not affect each other.

[0046] [Fig.4] shows a diagram of an energy spectrum captured by a camera gamma from three radioactive sources (Am241, Co57, and Bal33). In [Fig. 4], the horizontal axis represents the energy, in terms of channel value, and the vertical axis represents the count value; and the light gray area provides valid information, while the dark gray area provides noise information. As shown in [Fig. 4], the gamma camera imaging method according to the embodiment of the present application determines four monitored energy regions from the total energy spectrum, including two branches of Am241 (shown in the figure as peaks of the spectrum, namely the first peak and the second peak), one branch of Co57 (indicated by the third peak), one branch of Bal33 (indicated by the fourth peak), which are regions with optimal signal-to-noise ratio. For these four monitored energy regions, imaging is performed separately.The characteristic peak at 355 kev of Bal33 cannot be used for imaging because its optimal signal-to-noise region does not meet the threshold requirements.

[0047] The images obtained by image reconstruction of these four monitored energy regions are normalized, and the normalized images are superimposed to form a composite image. [Fig. 5] shows a diagram of a result image obtained by image reconstruction by means of a gamma camera using the gamma camera imaging method according to an embodiment of the present application from the three radioactive sources (Am241, Ca57 and Bal33) of [Fig. 4]. In [Fig. 5], the first peak and the second peak are used for reconstruction in order to to generate an image of Am241, the third peak is used for reconstruction to generate an image of Bal33, and the fourth peak is used for reconstruction to generate an image of Co57, the positions of which are indicated in the figure with arrows.

[0048] The image obtained by the gamma camera imaging method according to the embodiment of the present application (as shown in [Fig. 5]) contains more information about radioactive materials than the image obtained by the conventional method (as shown in [Fig. 2]). Since the gamma camera does not have sufficient detection efficiency and energy definition, there is a higher probability that weaker peaks overlap each other, and thus a conventional peak discovery method based on the shape of the graph cannot find peaks well. In contrast, the present method uses a scanning method similar to peak discovery in a nuclide library.Since there are not many types of radioactive materials that can be detected by the gamma camera, even if all detectable radioactive materials are scanned, the computational amount and real-time processing speed are within acceptable ranges. In some special cases, such as that of high-energy radioactive materials (such as Co60), since the signal-to-noise ratio is improved, only a few dozen events can be accumulated to make a better image, which can reduce the measurement time. For example, the optimal imaging energy region in the energy spectrum of Co60 in [Fig. 6] is in the 300th to 450th channels (shown in the figure as a box). Although no peak is observed on the energy spectrum, the method according to the embodiment of the present application can obtain a very obvious reconstruction image.

[0049] The method according to the embodiment of the present application mainly shows the types and distribution of radioactive materials in the field of view of a gamma camera. For the application in the gamma camera, the presence and location information of radioactive materials is more important than their relative strength, and therefore, if it is necessary to check the strength and weakness information of the radioactive materials, an ordinary display mode can be used for further display.

[0050] As another example, [Fig.7] shows a comparison diagram of a result image obtained by image reconstruction by means of a gamma camera using a conventional method from two radioactive sources (Am241 and Co57) and a result image obtained by image reconstruction by means of a gamma camera using the gamma camera imaging method according to an embodiment of the present application from the same radioactive sources. [Fig.7] is shown by Figs. 7(a) on the left and 7(b) on the right, among which [Fig.7](a) is a gamma image obtained by the conventional method, and [Fig.7](b) is a gamma image obtained by the method according to the embodiment of the present application. Within a radiant field of view measured by the gamma camera, there are two radioactive spot sources, namely Am241 and Co57. From the left image, only a bright spot of Am241 can be observed in the middle of the left side, because the Am241 source has a high activity and the background is very bright as a whole, so that it obscures a bright spot of Co57. From the right image, the images of the two spot sources (Am241, Co57) are all obvious (Am241 on the left, Co57 on the right).It should be noted that the method according to the embodiment of the present application may assign a respective reconstructed image with different channel colors so that the resulting gamma image is a colored image. For example, Am241 may be represented in cyan, Co57 may be displayed in red. The assignment of color channels may differ from the example and may be set as required.

[0051] A gamma camera imaging device according to one embodiment of the present application will be described hereinafter. [Fig. 8] shows a block diagram of a gamma camera imaging device according to one embodiment of the present application. As shown in [Fig. 8], the gamma camera imaging device 800 according to the embodiment of the present application comprises a selection module 801, an image reconstruction module 802, a normalization module 803, and a superposition module 804. Specifically, the selection module 801 is configured to select, from energy spectra captured by a gamma camera on one or more radioactive materials, one or more energy domains of each radioactive material among the one or more radioactive materials, which are selected as one or more monitored energy regions of the radioactive material.The image reconstruction module 802 is configured to perform image reconstruction on the monitored energy regions of each of the one or more radioactive materials. The normalization module 803 is configured to perform normalization on the images obtained through the image reconstruction. The superposition module 804 is configured to perform superposition on the normalized images to form a composite image.

[0052] In some embodiments, the selection module 801 may comprise: a peak discovery module 8011 configured to scan the energy spectra to find peaks, and compare the peaks with the branch energies of respective radioactive materials recorded in a predetermined nuclide library to determine the radioactive material(s); a module branch determination module 8012 configured to determine, for each radioactive material among the one or more radioactive materials, a portion of the branches of the radioactive material having a relatively higher branch ratio, or lower energy, as one or more branches of the radioactive material to be monitored; and an energy domain determination module 8013 configured to determine, for each branch among the one or more branches of the radioactive material, an energy domain centered on the central energy of the branch and having the width of a half-maximum width of a peak corresponding to the branch, as one of the one or more monitored energy regions of the radioactive materials.

[0053] In some embodiments, the image reconstruction module 802 may comprise: a closed region determination module 8021 configured to determine, for each of the images obtained through the image reconstruction, whether or not there is a closed area in the image; and an energy region adjustment module 8022 configured to adaptively adjust, in the case where there is a closed region in the image and if the ratio of the contrast of the closed area to the contrast of a background area outside the closed area is less than a predetermined threshold, the energy domains of the monitored energy regions corresponding to the image.

[0054] In some embodiments, the energy region adjustment module 8022 may be further configured to: gradually expand or contract an energy region to be adjusted in a predetermined energy step, until the ratio of the contrast of the enclosed area to the contrast of a background area outside the enclosed area reaches the predetermined threshold.

[0055] In some embodiments, the image reconstruction module 802 may further comprise a rejection module 8023 configured to reject, in the event that there is not a closed region in the image, the energy domains of the monitored energy regions corresponding to the image. In some embodiments, the rejection module 8023 may further be configured to: reject, in the event that there is not a closed region in the image, the energy domains of the monitored energy regions corresponding to the image after a predetermined period of time.

[0056] The above-described gamma camera imaging method and device according to the embodiment of the present application can be used in a gamma camera to obtain an enhanced gamma image, which will be used in combination with an optical image for the identification of radioactive materials and their distribution information. According to the gamma camera imaging method and the gamma camera imaging device in the present application, each monitored energy region of each radioactive material is analyzed separately, which allows all radioactive materials to be taken into account, and thus the background noise can be reduced and the signal-to-noise ratio can be improved. Furthermore, according to the gamma camera imaging method and the gamma camera imaging device in the present application, only the projected images of moving radioactive materials need to be refreshed in the dynamic measurement mode, so that the imaging of moving materials and the imaging of stationary materials do not affect each other.

[0057] In some embodiments, in accordance with the present application, there is further provided a gamma camera imaging device, comprising: instructions for storing in memory; a processor configured to execute the instructions stored in memory to implement the gamma camera imaging method described above.

[0058] In some embodiments, in accordance with the present application, there is further provided a gamma camera, comprising the gamma camera imaging device described above.

[0059] [Fig. 9] shows an exemplary block diagram of a computing device that is applicable to the operation of a gamma camera imaging device according to one embodiment of the present application. As shown, the computing device 900 comprises one or more processors or processor cores 901 and a memory 902. For the purposes of this application (including the claims), the term "processor" and the expression "processor core" may be considered synonymous, unless expressly stated otherwise. The processor 901 may comprise any type of processor, such as a central processing unit, a microprocessor, and the like. The processor 901 may be implemented as an integrated circuit having multiple cores, for example, a multi-core microprocessor. In one embodiment, the memory 902 may be system memory. In some embodiments, the memory 902 may be integrated with the processor 901.The computing device 900 may include a mass storage device 903 (e.g., a disk, a hard disk drive, volatile memory (e.g., dynamic random access memory, DRAM), a compact disc read-only (CD-ROM), a digital versatile disc (DVD), and the like). In general, the memory 902 and / or the mass storage device 903 may be any type of temporary and / or permanent storage, including, but not limited to, volatile and non-volatile memories, optical, magnetic, and / or solid-state mass storage, and the like. The volatile memory may include, but is not limited to, static and / or dynamic random access memory. The non-volatile memory may include, but is not limited to, erasable and programmable read-only memory. electrically, phase change memory, resistive memory, and the like.

[0060] The computing device 900 may further include an input / output (I / O) device 904 (e.g., a display (e.g., a touchscreen display), a keyboard, a cursor control, a remote control, a game controller, an image capture device, etc.), and a communication interface 905 (e.g., a network interface card, a modem, an infrared receiver, a radio receiver (e.g., Bluetooth), and so on). The communication interface 905 may communicate with other devices via wiring or wirelessly to exchange data. For example, via the communication interface 905, gamma images may be transmitted for use in combination with optical images.

[0061] The components of the computing device 900 may be coupled to each other via a system bus 906, which represents one or more buses. In the case of multiple buses, these may be bridged by one or more bus bridges (not shown). Each of these components may perform its conventional functions known in the art. Specifically, the memory 902 and the mass storage device 903 may be employed to store a working copy and a permanent copy of programming instructions for operation of the gamma camera imaging device. The components may be implemented by assembly instructions supported by the processor(s) 901 or any high-level language that can be compiled into such instructions.A permanent copy of the programming instructions may be placed in the mass storage device 903 at the factory, or may be distributed in the field, for example, by a distribution medium (not shown) (e.g., a compact disc (CD)) or via a communication interface 905 (from a dispenser (not shown)). Thus, in some embodiments, in accordance with the present application, there is provided a computer-readable storage medium storing instructions that are executable by the processor for implementing the gamma camera imaging method as discussed above.

[0062] The number, capabilities, and / or capacity of the components may vary depending on whether the computing device 900 is used as a stationary computing device or is used as a mobile computing device. In various implementations, the computing device 900 may include one or more components of a laptop computer, a netbook, an ultrabook, a feature phone, a tablet device, a personal digital assistant (PDA), an ultramobile PC, a mobile phone, or a digital camera. In another implementation, the computing device 900 may be any other electronic device that is capable of processing data.

[0063] The above detailed description of embodiments of the present application covers many specific details in order to enable a complete understanding of the present application. It will, however, be apparent to those skilled in the art that the present application can be implemented without some of these specific details. The above description of embodiments is intended only to enable a clearer understanding of the present application by illustrating examples of the present application. The present application is in no way limited to any specific configuration and methodological steps proposed below, but covers any replacement, modification and improvement of the elements, components and method steps concerned without departing from the teachings of the present application.

[0064] It should be noted that, in the claims, the words "encompass" or "comprise" do not exclude the presence of elements or assemblies which are not listed in the claims. The article "a" or "an" which precedes a component or assembly does not exclude the existence of several such components or assemblies.

[0065] It should also be further noted that the language used in this specification is provided primarily for the purpose of readability and teaching, and not for explaining or defining the subject matter of this application. Thus, without departing from the essence and scope of the appended claims, numerous changes and modifications may be made by those skilled in the art. With respect to the scope of this application, the descriptions herein are illustrative and not limiting, and the scope of this application is limited by the appended claims.

Claims

Claims

1. A gamma camera imaging method, comprising: selecting (S 101), from energy spectra captured by a gamma camera of one or more radioactive materials, one or more energy domains of each radioactive material from among the one or more radioactive materials as one or more monitored energy regions of the radioactive material; performing (S 102) image reconstruction on each of the monitored energy regions of each radioactive material from among the one or more radioactive materials; performing (S 103) normalization on images obtained via the image reconstruction to obtain normalized images; and performing (S 104) superposition on the normalized images to form a composite image.

2. The gamma camera imaging method of claim 1, wherein the selection comprises: scanning energy spectra to find peaks and comparing the peaks with the branch energies of the respective radioactive materials recorded in a predetermined nuclide library to determine the one or more radioactive materials; determining, for each radioactive material among the one or more radioactive materials, a portion of the branches of the radioactive material having a relatively higher branch ratio, or lower energy, as one or more branches of the radioactive material to be monitored;and determining, for each branch of the one or more branches of the radioactive material, an energy domain centered on the central energy of the branch and having the width of a full width at half maximum of a peak corresponding to the branch, as one of the one or more monitored energy regions of the radioactive material.;

3. A gamma camera imaging method according to claim 1, further comprising: determining, for each of the images obtained through the image reconstruction, whether there is a closed area in the image; and adaptively adjusting, in the case where there is a closed region in the image and if the ratio of the contrast of the closed area to the contrast of a background area outside the closed area is less than a predetermined threshold, the energy domains of the monitored energy regions corresponding to the image.

4. The gamma camera imaging method of claim 3, wherein the adaptive adjustment comprises: gradually expanding or reducing an energy region to be adjusted in a predetermined energy step, until the ratio of the contrast of the enclosed area to the contrast of a background area outside the enclosed area reaches the predetermined threshold.

5. The gamma camera imaging method of claim 3, further comprising: rejecting, in the case where there is not a closed region in the image, the energy domains of the monitored energy regions corresponding to the image.

6. The gamma camera imaging method of claim 3, further comprising: discarding, in the event that there is not a closed region in the image, energy domains of the monitored energy regions corresponding to the image after a predetermined period of time.

7. The gamma camera imaging method of claim 1, wherein the superimposing comprises: superimposing the normalized images in different color channels to form the composite image.

8. A gamma camera imaging device, comprising: a selection module (S801) configured to select, from energy spectra captured by a gamma camera of one or more radioactive materials, one or more energy domains of each radioactive material among the one or more radioactive materials, as one or more monitored energy regions of the radioactive material; an image reconstruction module (802) configured to perform image reconstruction on each of the energy regions monitored of each radioactive material among the one or more radioactive materials; a normalization module (803) configured to perform normalization on images obtained through image reconstruction to obtain normalized images; and a superposition module (804) configured to perform superposition on the normalized images to form a composite image.

9. The gamma camera imaging device according to claim 8, wherein the selection module comprises: a peak discovery module (8011) configured to scan the energy spectra to find peaks, and comparing the peaks with the branch energies of the respective radioactive materials recorded in a predetermined nuclide library to determine the one or more radioactive materials; a branch determination module (8012) configured to determine, for each radioactive material among the one or more radioactive materials, a portion of the branches of the radioactive material having a relatively higher branch ratio, or lower energy, as one or more branches of the radioactive material to be monitored;and an energy domain determination module (8013) configured to determine, for each branch of the one or more branches of the radioactive material, an energy domain centered on the central energy of the branch and having the width of a half-maximum width of a peak corresponding to the branch, as one of the one or more monitored energy regions of the radioactive material.;

10. The gamma camera imaging device of claim 8, wherein the image reconstruction module comprises: a closed region determination module (8021) configured to determine, for each of the images obtained through the image reconstruction, whether or not there is a closed area in the image; and an energy region adjustment module (8022) configured to adaptively adjust, in the case where there is a closed region in the image and whether the ratio of the contrast of the closed area to the contrast of a background area outside the closed area is below a predetermined threshold, the energy domains of the monitored energy regions corresponding to the image.

11. The gamma camera imaging device of claim 10, wherein the energy region adjustment module is further configured to gradually expand or reduce an energy region to be adjusted in a predetermined energy step, until the ratio of the contrast of the enclosed area to the contrast of a background area outside the enclosed area reaches the predetermined threshold.

12. The gamma camera imaging device of claim 10, wherein the image reconstruction module further comprises: a rejection module (8023) configured to reject, in the case where there is not a closed region in the image, the energy domains of the monitored energy regions corresponding to the image.

13. The gamma camera imaging device of claim 10, wherein the image reconstruction module further comprises: a rejection module (8023) configured to reject, in the case where there is not a closed region in the image, the energy domains of the monitored energy regions corresponding to the image after a predetermined period of time.

14. A gamma camera imaging device comprising: a memory (902) storing instructions; and a processor (901) configured to execute the instructions stored in the memory to implement the gamma camera imaging method according to any one of claims 1 to 7.

15. A computer-readable storage medium storing instructions that are executable by a processor to implement the gamma camera imaging method according to any one of claims 1 to 7.

16. A gamma camera comprising: the gamma camera imaging device according to any one of claims 8 to 14.

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