Image processing device, image processing method, and image processing program

Abstract

To provide an image processing device, an image processing method, and an image processing program capable of accurately identifying a stationary phase while suppressing the time required for processing.SOLUTION: A processor included in an image processing device acquires projection data corresponding to phases identified by an electrocardiogram, imaged in synchronization with the electrocardiogram of a subject, with the radiation sequentially irradiated from multiple directions to the imaging site of the subject, identifies a provisional stationary phase assumed to be the stationary phase of the subject on the basis of a first reconstructed image reconstructed from the projection data corresponding to phases included in a first phase range among the phases, generates a second reconstructed image which is reconstructed from the projection data corresponding to phases included in the first phase range and in a second phase range including the provisional stationary phase among the phases and in which motion of the subject is corrected, and identifies the stationary phase of the subject on the basis of the second reconstructed image.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an image processing device, an image processing method, and an image processing program. [Background technology]

[0002] In an examination using a radiation CT (Computed Tomography) device, a technique is known in which the periodic movement of the heart is analyzed from electrocardiographic information of the subject obtained during imaging, and the stationary phase, which is the phase with the least movement, is identified (see, for example, Patent Document 1). Using the identified stationary phase, for example, imaging can be performed in synchronization with the stationary phase, or a diagnostic image can be reconstructed using projection data in the stationary phase. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-204961 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with conventional techniques, detecting the stationary phase with higher accuracy can take a long time to process.

[0005] The present disclosure has been made in consideration of the above circumstances, and aims to provide an image processing device, an image processing method, and an image processing program that can accurately identify the stationary phase while reducing the time required for processing. [Means for solving the problem]

[0006] In order to achieve the above object, an image processing device of a first aspect of the present disclosure includes at least one processor, which acquires projection data corresponding to a phase identified by the electrocardiogram by using radiation sequentially irradiated from multiple directions to an imaging area of ​​the subject in synchronization with the electrocardiogram of the subject, identifies a provisional still phase that is assumed to be the still phase of the subject based on a first reconstructed image reconstructed from projection data corresponding to a phase included in a first phase range among the phases, generates a second reconstructed image reconstructed from projection data corresponding to a phase included in a second phase range among the phases that is included in the first phase range and includes the provisional still phase, and corrects the movement of the subject, and identifies the still phase of the subject based on the second reconstructed image.

[0007] The image processing device of the second aspect is the image processing device of the first aspect, wherein the processor generates a second reconstructed image under the first reconstruction conditions, identifies a third phase range that includes the still phase of the subject from the phase corresponding to the second reconstructed image, and identifies the still phase of the subject based on the third reconstructed image that corresponds to the phase included in the third phase range and that has been reconstructed under the second reconstruction conditions from the projection data and has been corrected for the movement of the subject, and the second reconstruction conditions are processing conditions that result in a reconstructed image of higher image quality than the first reconstruction conditions.

[0008] In the image processing device of a third aspect, in the image processing device of the second aspect, the processor specifies, as a third phase range, a range corresponding to a phase in which the movement of the subject is smaller than a predetermined threshold.

[0009] A fourth aspect of the image processing device is the image processing device of the first aspect, wherein the processor generates a first reconstructed image at a first phase interval, generates a second reconstructed image at a second phase interval wider than the first phase interval, generates a third reconstructed image reconstructed from projection data corresponding to the phase at which the second reconstructed image was generated, and identifies the static phase of the subject based on the deviation between the second reconstructed image and the third reconstructed image for each corresponding phase.

[0010] An image processing device of a fifth aspect is the image processing device of the fourth aspect, wherein the processor identifies a phase in which the deviation between the second reconstructed image and the third reconstructed image is minimum as a stationary phase of the subject.

[0011] An image processing device of a sixth aspect is the image processing device of the first aspect, wherein the first phase range is a range corresponding to at least one of a diastole and a systole of the subject.

[0012] In order to achieve the above object, an image processing method of a seventh aspect of the present disclosure includes a processor provided in an image processing device, which acquires projection data corresponding to a phase identified by the electrocardiogram using radiation sequentially irradiated from multiple directions onto the imaging area of ​​the subject, identifies a provisional still phase that is assumed to be the still phase of the subject based on a first reconstructed image reconstructed from projection data corresponding to a phase included in a first phase range among the phases, generates a second reconstructed image reconstructed from projection data corresponding to a phase included in a second phase range among the phases that is included in the first phase range and includes the provisional still phase, and corrects the movement of the subject, and identifies the still phase of the subject based on the second reconstructed image.

[0013] In order to achieve the above object, an image processing program of an eighth aspect of the present disclosure causes a processor provided in an image processing device to perform a process of acquiring projection data corresponding to a phase identified by the electrocardiogram using radiation sequentially irradiated from multiple directions to the imaging area of ​​the subject in synchronization with the electrocardiogram of the subject, identifying a provisional still phase that is assumed to be the still phase of the subject based on a first reconstructed image reconstructed from projection data corresponding to a phase included in a first phase range among the phases, generating a second reconstructed image in which the movement of the subject has been corrected, reconstructed from projection data corresponding to a phase included in a second phase range among the phases that is included in the first phase range and includes the provisional still phase, and identifying the still phase of the subject based on the second reconstructed image. [Effects of the Invention]

[0014] According to the present disclosure, it is possible to accurately identify the stationary phase while reducing the time required for processing. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a configuration diagram illustrating an example of the configuration of a radiation CT imaging apparatus according to an embodiment. [Figure 2] FIG. 2 is a configuration diagram illustrating an example of a configuration of a console according to an embodiment. [Figure 3] FIG. 2 is a functional block diagram illustrating an example of functions of a console according to an embodiment. [Figure 4A] FIG. 10 is a diagram schematically illustrating an example of an image of a cardiac phase. [Figure 4B] FIG. 10 is a diagram for explaining a method for specifying a provisional optimal cardiac phase (optimal cardiac phase in CardioHarmony (registered trademark)). [Figure 5] 10 is a flowchart illustrating an example of the flow of image processing according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the embodiment.

[0017] [First embodiment] First, an example of the configuration of a radiation CT (Computed Tomography) imaging apparatus according to this embodiment will be described. Fig. 1 shows a configuration diagram illustrating an example of the configuration of a radiation CT imaging apparatus 10 according to this embodiment.

[0018] 1, the radiation CT imaging apparatus of this embodiment includes a gantry 20, a bed 27, and a console 30. In the following description, the horizontal direction in FIG. 1 is defined as the X-axis, the vertical direction as the Y-axis, and the direction perpendicular to the XY plane as the Z-axis.

[0019] The gantry 20 has an opening 26, and the subject S to be imaged is placed on a bed 27 and placed in the opening 26. The gantry 20 and the bed 27 are capable of moving relatively in the Z-axis direction.

[0020] Inside the gantry 20, a radiation generator 23 having a radiation tube (not shown), a bowtie filter 24, a collimator 25, and a detector panel 28 are arranged facing each other with the subject S in between. The radiation R irradiated from the radiation generator 23 is shaped by the bowtie filter 24 and the collimator 25 into a beam shape suitable for the size of the subject S, and is then irradiated onto the subject S. The detector panel 28 detects the radiation that has passed through the subject S, and generates projection data according to the dose of the detected radiation.

[0021] The radiation generator 23 and the detector panel 28 are rotated around the subject S by a rotation drive unit (not shown) of the gantry 20. The irradiation of radiation from the radiation generator 23 and the detection of radiation by the detector panel 28 are repeated as they rotate, thereby obtaining projection data at various projection angles. The plurality of projection data obtained by the detector panel 28 are output to the console 30.

[0022] The dose of radiation irradiated from the radiation generator 23, the rotation speed of the gantry 20, and the relative movement speed between the gantry 20 and the bed 27 are set by the console 30 based on scan conditions input by a user such as a technician. In the case of ECG (Electrocardiogram) synchronized imaging, imaging is performed in synchronization with the phase of cardiac movement (cardiac phase) based on information from an electrocardiograph (not shown) attached to the subject S, and in the case of asynchronous imaging, imaging is performed under automatic exposure control.

[0023] The console 30 of this embodiment controls the acquisition of projection data, identifies stationary phases, and generates medical images. The console 30 of this embodiment is an example of an image forming apparatus of the present disclosure. As an example, the console 30 of this embodiment is a server computer.

[0024] 2, the console 30 includes a control unit 32, a memory unit 34, an I / F (Interface) unit 35, an operation unit 36, and a display unit 38. The control unit 32, the memory unit 34, the I / F unit 35, the operation unit 36, and the display unit 38 are connected via a bus 39 such as a system bus or a control bus so that various information can be exchanged between them.

[0025] The control unit 32 of this embodiment controls the overall operation of the console 30. The control unit 32 includes a CPU (Central Processing Unit) 32A, a ROM (Read Only Memory) 32B, and a RAM (Random Access Memory) 32C. The ROM 32B stores in advance various programs, including an image processing program 33 (described later), which are executed by the CPU 32A. The RAM 32C temporarily stores various data.

[0026] The storage unit 34 stores the projection data output from the detector panel 28 and various other information. Specific examples of the storage unit 34 include a storage medium such as an HDD (Hard Disk Drive), an SSD (Solid State Drive), and a flash memory.

[0027] The I / F unit 35 communicates various types of information with a rotation drive unit (not shown) of the gantry 20, the radiation generation device 23, and the detector panel 28 via wired or wireless communication. The console 30 of this embodiment receives projection data from the detector panel 28 via the I / F unit 35. The received projection data is stored in the storage unit 34 in a state associated with the cardiac phase.

[0028] The console 30 acquires a plurality of pieces of projection data from the detector panel 28 via the I / F unit 35. The control unit 32 performs reconstruction processing on the acquired plurality of pieces of projection data to generate a tomographic image of the subject S.

[0029] The operation unit 36 ​​is used by the user to input scan conditions for acquiring projection data, instructions and various information regarding image generation and display, etc. The operation unit 36 ​​is not particularly limited, and examples thereof include various switches, buttons, a touch panel, a touch pen, a keyboard, and a mouse. The display unit 38 displays various information, medical images, etc. The operation unit 36 ​​and the display unit 38 may be integrated into a touch panel display. Alternatively, for example, the operation unit 36 ​​may receive voice input from the user.

[0030] 3 shows a functional block diagram illustrating an example of the functions of the console 30. The console 30 includes an acquisition unit 40, a provisional stationary phase identification unit 42, a correction processing unit 44, and a stationary phase identification unit 46. As an example, in the console 30 of this embodiment, the CPU 32A of the control unit 32 executes the image processing program 33, so that the CPU 32A functions as the acquisition unit 40, the provisional stationary phase identification unit 42, the correction processing unit 44, and the stationary phase identification unit 46.

[0031] The acquisition unit 40 has a function of acquiring projection data from the detector panel 28. Specifically, as described above, the acquisition unit 40 acquires projection data corresponding to phases identified by the electrocardiogram, which is acquired in synchronization with the electrocardiogram of the subject S using radiation sequentially irradiated from multiple directions to the subject S, from the detector panel 28 via the I / F unit 35. Note that the acquisition unit 40 may also be configured to acquire, from the storage unit 34, projection data that has been acquired in advance from the detector panel 28 and stored in the storage unit 34 in association with cardiac phases. The acquisition unit 40 outputs the acquired projection data to the provisional resting phase identification unit 42 and the correction processing unit 44.

[0032] The provisional resting phase identifying unit 42 has a function of identifying a provisional resting phase to be assumed as a resting phase based on a first reconstructed image reconstructed from projection data corresponding to each of the phases included in the cardiac diastole and systole. The resting phase refers to a phase in which cardiac movement is smallest among all phases, or a phase that is close to resting. The resting phase may also be referred to as an optimal cardiac phase. Each of the cardiac diastole and systole in this embodiment is an example of a first phase range in the present disclosure. The first reconstructed image reconstructed by the provisional resting phase identifying unit 42 is also an example of a first reconstructed image in the present disclosure.

[0033] The method by which the provisional resting phase identifying unit 42 identifies the provisional resting phase is not limited. For example, the phase detected as the optimal cardiac phase by CardioHarmony (registered trademark), an automatic phase search technology, may be identified as the provisional resting phase. CardioHarmony (registered trademark) is a technology that extracts the amount of movement of the entire heart from images (reconstructed images) created for each cardiac phase and detects the phase at which this amount is smallest as the optimal cardiac phase. Specifically, first, cardiac phase images of 0 to 99% are generated for the entire heart, as shown in FIG. 4A. Then, the amount of movement is extracted for each phase, centered on the contrast-enhanced portion of the created image. Furthermore, the correspondence between the amount of movement and the phase is identified as shown in the graph in FIG. 4B, and the phase at which the amount of movement is smallest is detected as the optimal cardiac phase. The optimal cardiac phase is detected for each of the cardiac diastole and systole. In other words, two optimal cardiac phases are detected in one cycle of cardiac expansion and contraction. Alternatively, the technology described in Japanese Patent No. 4157302, for example, may be used.

[0034] The temporary rest phase specifying unit 42 outputs the specified temporary rest phase to the correction processing unit 44.

[0035] The correction processor 44 has a function of generating a second reconstructed image in which cardiac motion has been corrected by reconstructing projection data corresponding to phases included in both the diastole and systole of the heart and within a phase range including the temporary resting phase. As an example, the correction processor 44 of this embodiment generates the second reconstructed image by reconstructing projection data corresponding to phases included in a ±10% range of the temporary resting phase (see FIG. 4B ) while correcting cardiac motion during imaging. Specifically, when the temporary resting phase in diastole accounts for 77%, projection data corresponding to phases included in a phase range of 67% to 87% is used. Furthermore, when the temporary resting phase in systole accounts for 44%, projection data corresponding to phases included in a phase range of 34% to 54% is used. The ±10% range of the temporary resting phase in this embodiment is an example of the second phase range of the present disclosure.

[0036] The method by which the correction processing unit 44 corrects the cardiac motion, in other words, the method by which the correction processing unit 44 reconstructs the projection data while correcting the cardiac motion, is not limited. For example, the correction processing unit 44 may obtain cardiac motion information from an image, and reconstruct the projection data using the motion information and the ratio of the tube currents used to capture the image, thereby generating a second reconstructed image in which the cardiac motion has been corrected.

[0037] A first image and a second image of a directly opposed position are generated using projection data corresponding to a phase within a range of ±10% of the provisional static phase, and noise reduction processing and post-noise-reduction registration processing are performed on each of the first image and the second image to obtain motion information of the subject. At this time, at least one of the type and parameters of a noise reduction filter used in the noise reduction processing and parameters of a non-rigid registration algorithm used in the registration processing may be adjusted based on the ratio of the tube currents when the first image and the second image were acquired, and a second reconstructed image may be generated by reconstructing the projection data using the motion information. The reconstructed image reconstructed by the static phase identification unit 46 is an example of the second reconstructed image of the present disclosure.

[0038] The second reconstructed image generated by the correction processing unit 44 is output to the stationary phase identifying unit 46.

[0039] The stationary phase identifying unit 46 has a function of identifying the stationary phase of the heart based on the second reconstructed image. The method by which the stationary phase identifying unit 46 identifies the stationary phase is not limited. For example, the phase detected as the optimal cardiac phase using the above-mentioned CardioHarmony (registered trademark) may be identified as the stationary phase. The stationary phase identifying unit 46 of this embodiment identifies the stationary phase in the diastole and the stationary phase in the systole of the heart.

[0040] Next, the operation of the console 30 of this embodiment will be described.

[0041] As an example, when the console 30 of this embodiment receives display conditions for the radiological image X and ultrasound image U to be displayed, input by the user via the operation unit 36, the CPU 32A of the control unit 32 executes the image processing program 33 stored in the ROM 32B, thereby performing image processing, an example of which is shown in Fig. 5. Fig. 5 shows a flowchart illustrating an example of the flow of image processing in the console 30 of this embodiment.

[0042] First, in step S100 of FIG. 5, the acquisition unit 40 acquires projection data associated with cardiac phases, which is obtained by imaging the heart of the subject S using the radiation CT imaging device 10, as described above.

[0043] In the next step S102, the temporary resting phase identifying unit 42 generates a first reconstructed image as described above by reconstructing projection data corresponding to the phases included in each of the cardiac diastole and systole (see FIG. 4B).

[0044] In the next step S104, the tentative stationary phase identifying unit 42 identifies the tentative stationary phase using the first reconstructed image generated in step S102, as described above.

[0045] It should be noted that, when the above-described temporary stationary phase identifying unit 42 uses CardioHarmony (registered trademark), the processes of steps S102 and S104 are performed together.

[0046] In the next step S106, the correction processing unit 44 extracts, as described above, projection data corresponding to phases within a phase range of ±10% (see Figure 4B) of the provisional static phase identified in step S104 from the projection data acquired in step S100.

[0047] In the next step S108, the correction processing unit 44 reconstructs the projection data extracted in step S106 while correcting for the movement of the heart during imaging, as described above, to generate a second reconstructed image.

[0048] In the next step S110, the stationary phase identification unit 46 identifies the stationary phase based on the second reconstructed image generated in step S108. The stationary phase identified here is output to a predetermined output destination. For example, when outputting to the display unit 38 of the console 30, information indicating the stationary phase and the second reconstructed image at the stationary phase may be displayed on the display unit 38. When outputting to the storage unit 34, the information may be stored in the storage unit 34 in association with at least one of the projection data acquired by the acquisition unit 40 and the second reconstructed image at the stationary phase. When the processing of step S110 is completed, the image processing shown in FIG. 5 is completed.

[0049] As described above, the console 30 of this embodiment identifies a tentative stationary phase using a method that requires a relatively small processing load and little processing time, and generates a reconstructed image in which cardiac motion has been corrected for phases in a phase range narrowed down by the identified tentative phase. The stationary phase is then identified from the reconstructed image in which cardiac motion has been corrected. As a result, the console 30 of this embodiment can accurately identify the stationary phase while reducing the time required for processing.

[0050] Second Embodiment In this embodiment, the processes performed by the correction processing unit 44 and the stationary phase identification unit 46 are different, and therefore, the different processes will be described.

[0051] When generating the second reconstructed image in which the motion of the subject has been corrected, the correction processing unit 44 of this embodiment generates the second reconstructed image under the first reconstruction condition. Then, the correction processing unit 44 identifies a phase range including the still phase of the subject from the phase corresponding to the second reconstructed image. This third phase range is a phase range in which the motion of the heart is less than a predetermined threshold. Note that the third phase range is a range that is equal to or less than ±10% of the provisional still phase and is included in the phase range of ±10% of the provisional still phase.

[0052] In addition, the correction processing unit 44 generates a third reconstructed image that is reconstructed from the projection data according to the second reconstruction conditions and that corresponds to a phase included in a phase range of ±5% of the newly identified tentative phase range, and in which the movement of the subject has been corrected.

[0053] Here, the second reconstruction condition is a condition for obtaining a reconstructed image of higher quality than the first reconstruction condition. In this case, the processing load for obtaining a high-quality image increases, and the time required for processing becomes relatively long. Examples of the reconstruction condition in this case include conditions related to the slice thickness and the slice interval.

[0054] On the other hand, the first reconstruction condition is a condition under which an image quality sufficient for phase detection can be obtained, and which is lower in image quality than the reconstructed image obtained under the second reconstruction condition. In this case, the image quality can be suppressed, and therefore the time required for processing can be shortened. The reconstruction conditions in this case include conditions related to the FOV (field of view), filter, and matrix size.

[0055] Furthermore, the correction processing unit 44 identifies the resting phase of the heart as described above based on the generated third reconstructed image.

[0056] In this manner, in the present embodiment, even when a corrected image in which cardiac motion has been corrected is reconstructed, the phase range is further narrowed down by a method that requires a relatively short processing time, and a higher-quality reconstruction is generated for the narrowed phase range. Therefore, the console 30 of the present embodiment can identify the stationary phase with higher accuracy while suppressing an increase in processing time.

[0057] Unlike the present embodiment, the processing of the temporary stationary phase identifying unit 42 may be omitted. That is, the processing of the correction processing unit 44 and stationary phase identifying unit 46 of the present embodiment may be executed for the entire phase range.

[0058] Third Embodiment In this embodiment, the processes performed by the temporary stationary phase identifying unit 42, the correction processing unit 44, and the stationary phase identifying unit 46 are different, and therefore, the different processes will be described.

[0059] The temporary stationary phase identifying unit 42 generates a first reconstructed image at a first phase interval.

[0060] The correction processing unit 44 and the temporary stationary phase identifying unit 42 generate a second reconstructed image at a second phase interval that is wider than the first phase interval.

[0061] The correction processing unit 44 also generates a third reconstructed image reconstructed from the projection data corresponding to the phase in which the second reconstructed image was generated. The third reconstructed image is a reconstructed image in which the cardiac motion has not been corrected.

[0062] The still phase identifying circuitry 46 then identifies the cardiac still phase based on the deviation between the second reconstructed image and the third reconstructed image for each corresponding phase. In this case, the still phase identifying circuitry 46 may identify the phase in which the deviation between the second reconstructed image and the third reconstructed image is minimum as the cardiac still phase.

[0063] In this manner, in this embodiment, the stationary phase is identified by comparing the second reconstructed image in which motion has been corrected with the third reconstructed image in which motion has not been corrected. As a result, the console 30 of this embodiment can identify the stationary phase through a relatively simple process.

[0064] As described above, according to the console 30 of each of the above embodiments, the stationary phase can be identified with high accuracy while reducing the time required for processing.

[0065] In each of the above embodiments, the following various processors can be used as the hardware structure of processing units that perform various processes, such as the acquisition unit 40, the temporary stationary phase identification unit 42, the correction processing unit 44, and the stationary phase identification unit 46. As described above, the various processors include a CPU, which is a general-purpose processor that executes software (programs) and functions as various processing units, as well as dedicated electrical circuits that are processors having a circuit configuration specifically designed to perform specific processes, such as a programmable logic device (PLD), which is a processor whose circuit configuration can be changed after manufacture, such as an FPGA (Field Programmable Gate Array), and an ASIC (Application Specific Integrated Circuit).

[0066] A single processing unit may be configured with one of these various processors, or may be configured with a combination of two or more processors of the same or different types (for example, a combination of multiple FPGAs, or a combination of a CPU and an FPGA). Also, multiple processing units may be configured with a single processor.

[0067] Examples of configuring multiple processing units with a single processor include, first, a form in which one processor is configured with a combination of one or more CPUs and software, and this processor functions as multiple processing units, as typified by computers such as client and server. Second, a form in which a processor is used to realize the functions of an entire system including multiple processing units with a single IC (Integrated Circuit) chip, as typified by systems on chips (SoCs). In this way, various processing units are configured using one or more of the above-mentioned various processors as a hardware structure.

[0068] Furthermore, more specifically, the hardware structure of these various processors can be an electric circuit that combines circuit elements such as semiconductor elements.

[0069] In the above embodiment, the image processing program 33 is pre-stored (installed) in the storage unit 34 of the console 30, but the present invention is not limited to this. The image processing program 33 may be provided in a form recorded on a recording medium such as a CD-ROM (Compact Disc Read Only Memory), a DVD-ROM (Digital Versatile Disc Read Only Memory), or a USB (Universal Serial Bus) memory. The image processing program 33 may also be downloaded from an external device via a network.

[0070] Furthermore, the configurations and operations of the radiation CT imaging apparatus 10 and the console 30, etc., described in the above embodiments are merely examples, and it goes without saying that they can be modified according to the circumstances without departing from the spirit of the present invention. It also goes without saying that the above embodiments can be combined as appropriate.

[0071] The following additional notes are provided regarding the above-described embodiment. (Appendix 1) at least one processor; The processor: an imaging region of a subject is imaged in synchronization with an electrocardiogram of the subject by using radiation sequentially irradiated from a plurality of directions, and projection data corresponding to a phase identified by the electrocardiogram is acquired; identifying a tentative stationary phase assumed to be a stationary phase of the subject based on a first reconstructed image reconstructed from the projection data corresponding to a phase included in a first phase range among the phases; generating a second reconstructed image in which the motion of the subject is corrected by reconstructing from the projection data corresponding to phases included in the first phase range and included in a second phase range including the temporary stationary phase, among the phases; Identifying a stationary phase of the object based on the second reconstructed image. Image processing device.

[0072] (Appendix 2) The processor: generating the second reconstructed image under a first reconstruction condition; identifying a third phase range including a stationary phase of the object from a phase corresponding to the second reconstructed image; identifying a static phase of the subject based on a third reconstructed image that is reconstructed from the projection data under a second reconstruction condition and that has been corrected for movement of the subject, the third reconstructed image corresponding to a phase included in the third phase range; The second reconstruction conditions are processing conditions that result in a reconstructed image of higher quality than the first reconstruction conditions. 2. The image processing device according to claim 1.

[0073] (Appendix 3) The processor: A range corresponding to a phase in which the movement of the subject is smaller than a predetermined threshold is identified as the third phase range. 3. The image processing device according to claim 2.

[0074] (Appendix 4) The processor: generating the first reconstructed image at a first phase interval; generating the second reconstructed image at a second phase interval wider than the first phase interval; generating a third reconstructed image reconstructed from the projection data corresponding to the phase at which the second reconstructed image was generated; Identifying a stationary phase of the subject based on a deviation between the second reconstructed image and the third reconstructed image for each corresponding phase. 2. The image processing device according to claim 1.

[0075] (Appendix 5) The processor: The phase in which the difference between the second reconstructed image and the third reconstructed image is smallest is identified as the stationary phase of the subject. 5. The image processing device according to claim 4.

[0076] (Appendix 6) The first phase range corresponds to at least one of a diastole and a systole of the subject. 6. An image processing device according to any one of claims 1 to 5.

[0077] (Appendix 7) The processor of the image processing device an imaging region of a subject is imaged in synchronization with an electrocardiogram of the subject by using radiation sequentially irradiated from a plurality of directions, and projection data corresponding to a phase identified by the electrocardiogram is acquired; identifying a tentative stationary phase assumed to be a stationary phase of the subject based on a first reconstructed image reconstructed from the projection data corresponding to a phase included in a first phase range among the phases; generating a second reconstructed image in which the motion of the subject is corrected by reconstructing from the projection data corresponding to phases included in the first phase range and included in a second phase range including the temporary stationary phase, among the phases; Identifying a stationary phase of the object based on the second reconstructed image. Image processing methods.

[0078] (Appendix 8) The processor of the image processing device includes: an imaging region of a subject is imaged in synchronization with an electrocardiogram of the subject by using radiation sequentially irradiated from a plurality of directions, and projection data corresponding to a phase identified by the electrocardiogram is acquired; identifying a tentative stationary phase assumed to be a stationary phase of the subject based on a first reconstructed image reconstructed from the projection data corresponding to a phase included in a first phase range among the phases; generating a second reconstructed image in which the motion of the subject is corrected by reconstructing from the projection data corresponding to phases included in the first phase range and included in a second phase range including the temporary stationary phase, among the phases; Identifying a stationary phase of the object based on the second reconstructed image. Image processing program to execute the process. [Explanation of symbols]

[0079] 10. Radiation CT imaging device 20 Gantry 23 Radiation Generator 24 Bowtie Filter 25 Collimator 26 Opening 27 berths 28 Detector Panel 30 Console 32 control unit, 32A CPU, 32B ROM, 32C RAM 33 Image Processing Program 34 Storage section 35 I / F section 36 Operation section 38 Display section 39 Bus 40 Acquisition Department 42 Temporary stationary phase identification unit 44 Correction processing section 46 Stationary phase identification section R Radiation S subject

Claims

1. at least one processor; The processor: Radiation is sequentially irradiated from a plurality of directions onto a region of a subject to be imaged, and imaging is performed in synchronization with an electrocardiogram of the subject, and projection data corresponding to a phase identified by the electrocardiogram is acquired; identifying a provisional stationary phase assumed to be a stationary phase of the subject based on a first reconstructed image reconstructed from the projection data corresponding to a phase included in a first phase range among the phases; generating a second reconstructed image in which the motion of the subject is corrected by reconstructing from the projection data corresponding to phases included in the first phase range and included in a second phase range including the temporary stationary phase, among the phases; Identifying a stationary phase of the object based on the second reconstructed image. Image processing device.

2. The processor: generating the second reconstructed image under a first reconstruction condition; identifying a third phase range including a stationary phase of the object from a phase corresponding to the second reconstructed image; identifying a stationary phase of the subject based on a third reconstructed image that is reconstructed from the projection data under a second reconstruction condition and that has been corrected for movement of the subject, the third reconstructed image corresponding to a phase included in the third phase range; The second reconstruction conditions are processing conditions that result in a reconstructed image of higher quality than the first reconstruction conditions. The image processing device according to claim 1 .

3. The processor: A range corresponding to a phase in which the movement of the subject is smaller than a predetermined threshold is identified as the third phase range. The image processing device according to claim 2 .

4. The processor: generating the first reconstructed image at a first phase interval; generating the second reconstructed image at a second phase interval wider than the first phase interval; generating a third reconstructed image reconstructed from the projection data corresponding to the phase at which the second reconstructed image was generated; Identifying a stationary phase of the subject based on a deviation between the second reconstructed image and the third reconstructed image for each corresponding phase. The image processing device according to claim 1 .

5. The processor: The phase in which the difference between the second reconstructed image and the third reconstructed image is smallest is identified as the stationary phase of the subject. The image processing device according to claim 4 .

6. The first phase range corresponds to at least one of a diastole and a systole of the subject. The image processing device according to claim 1 .

7. The processor of the image processing device Radiation is sequentially irradiated from a plurality of directions onto a region of a subject to be imaged, and imaging is performed in synchronization with an electrocardiogram of the subject, and projection data corresponding to a phase identified by the electrocardiogram is acquired; identifying a provisional stationary phase assumed to be a stationary phase of the subject based on a first reconstructed image reconstructed from the projection data corresponding to a phase included in a first phase range among the phases; generating a second reconstructed image in which the motion of the subject is corrected by reconstructing from the projection data corresponding to phases included in the first phase range and included in a second phase range including the temporary stationary phase, among the phases; Identifying a stationary phase of the object based on the second reconstructed image. Image processing methods.

8. The processor of the image processing device includes: Radiation is sequentially irradiated from a plurality of directions onto a region of a subject to be imaged, and imaging is performed in synchronization with an electrocardiogram of the subject, and projection data corresponding to a phase identified by the electrocardiogram is acquired; identifying a provisional stationary phase assumed to be a stationary phase of the subject based on a first reconstructed image reconstructed from the projection data corresponding to a phase included in a first phase range among the phases; generating a second reconstructed image in which the motion of the subject is corrected by reconstructing from the projection data corresponding to phases included in the first phase range and included in a second phase range including the temporary stationary phase, among the phases; Identifying a stationary phase of the object based on the second reconstructed image. Image processing program to execute the process.

Images