Radiation image processing device and program

Abstract

The present invention provides a radiation image processing device and program capable of accurately identifying the location of abnormal parts and other features in a subject. [Solution] The radiation image processing device is a radiation image processing device capable of acquiring motion images taken with radiation, and comprises a reconstruction unit that reconstructs a tomographic image based on a plurality of motion images in which the direction of radiation irradiation to the subject is different, and a generation unit that generates a tomographic motion image based on the tomographic image.

Description

Technical Field

[0005]

[0001] The present invention relates to a radiation image processing apparatus and a program.

Background Art

[0002] In postoperative patients such as intensive care patients, it is necessary to grasp the pathological conditions such as pulmonary emphysema, atelectasis, pneumonia, pleural effusion, pneumothorax, etc., and to perform appropriate treatment interventions for each. In such pathological conditions, diagnosis by CT (Computed Tomography) is ideal. However, there are also patients who have difficulty moving to the CT room, such as severely injured patients, so there is a possibility that appropriate treatment cannot be performed.

[0003] Therefore, as a radiation imaging system that substitutes for CT, a system capable of imaging a dynamic image of a subject is known. For example, Patent Document 1 discloses a configuration capable of imaging the respiratory dynamics of the human chest from a plurality of different directions.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the configuration described in Patent Document 1 only generates a plurality of dynamic images, and it is difficult to accurately specify the position (such as a three-dimensional position) of an abnormal part of a subject. <00000$30> An object of the present invention is to provide a radiation image processing apparatus and a program capable of accurately specifying the position of an abnormal part of a subject.

Means for Solving the Problems

[0007] The radiation image processing apparatus according to the present invention is A radiographic image processing device capable of acquiring radiographic motion images, A reconstruction unit that reconstructs a tomographic image based on multiple dynamic images with different radiation irradiation directions applied to the subject, A generation unit that generates a tomographic dynamic image based on the aforementioned tomographic image, It is equipped with.

[0008] The program according to the present invention is A program for a radiographic image processing device capable of acquiring radiographic motion images, On the computer, A reconstruction process that reconstructs a tomographic image based on multiple dynamic images with different radiation irradiation directions applied to the subject, A generation process that generates a dynamic tomographic image based on the aforementioned tomographic image, Make it run. [Effects of the Invention]

[0009] According to the present invention, the location of abnormal parts of a subject can be accurately identified. [Brief explanation of the drawing]

[0010] [Figure 1] This is a diagram showing a radiography system according to an embodiment of the present invention. [Figure 2] This block diagram shows the main components of the control system according to this embodiment. [Figure 3] This is a block diagram of the shooting control unit. [Figure 4] This is a diagram illustrating the irradiation direction of a radiation irradiation device. [Figure 5] This diagram illustrates the phase changes in the signal values ​​of each dynamic image. [Figure 6] This is a diagram to explain how to define a region of interest. [Figure 7] This flowchart shows an example of the operation of the tomographic dynamic image generation process by the imaging control unit. [Figure 8] This is a block diagram showing the image capture control unit related to the modified form.

Best Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail based on the drawings. FIG. 1 is a diagram showing a radiation imaging system according to an embodiment of the present invention.

[0012] As shown in FIG. 1, the radiation imaging system 1 according to the present embodiment is capable of taking still images and dynamic images, and is a system for home visit (mobile type) for going to a subject who has difficulty moving to take a radiation image. Note that the radiation imaging system 1 can be applied to, for example, a hospital room, an ICU (Intensive Care Unit), an operating room, and the like.

[0013] The radiation imaging system 1 includes a main body 10, one or more FPDs (Flat Panel Detectors) 20, and a radiation irradiation device 30.

[0014] ​​​​​​​​The FPD20 is a portable radiation detector that supports the shooting of still images and moving images. The FPD20 includes, for example, radiation detection elements arranged two-dimensionally on a glass substrate. The radiation detection elements are composed of semiconductor image sensors such as photodiodes. The radiation detection elements detect the radiation irradiated from a radiation irradiation device 30 (radiation source) and at least transmitted through a subject according to its intensity, convert the detected radiation into an electrical signal, and accumulate it. A switching unit such as a TFT (Thin Film Transistor) is connected to each radiation detection element, and the accumulation and reading of the electrical signal are controlled by the switching unit, and image data is acquired.

[0017] Note that the FPD20 may be an indirect conversion type that converts radiation into an electrical signal by a photoelectric conversion element via a scintillator, or a direct conversion type that directly converts radiation into an electrical signal.

[0018] In addition, the FPD20 is connected to the main body 10 of the radiation imaging system 1 via a communication network and is adapted to perform wired or wireless communication with the main body. Specifically, the FPD20 is adapted to receive various control signals from the main body 10 via a communication cable and transmit the generated image data to the main body 10.

[0019] Further, the main body 10 is provided with a storage unit (not shown) capable of storing the FPD20. The main body 10 is transported to a hospital room with the FPD20 stored in the storage unit.

[0020] The radiation irradiation device 30 includes a synchronization signal output unit (not shown), a generator (not shown), a radiation source (not shown), and the like.

[0021] The synchronization signal output unit outputs a pulsed synchronization signal to the generator and the FPD20 respectively based on the operation of an exposure switch 41A described later. In the shooting of a still image, the synchronization signal is transmitted only once for each still image, and in the shooting of a moving image, the synchronization signal of the same period is repeatedly transmitted a plurality of times.

[0022] The generator is configured to apply a voltage to the radiation source according to preset radiation irradiation conditions (tube voltage, tube current, irradiation time, etc.) each time a synchronization signal is input from the synchronization signal output unit.

[0023] The radiation source (tube) includes a rotating anode and a filament. The rotating anode consists of a target, a rotor or anode rotor that rotates the anode, an anode shaft, and bearings (not shown). The anode rotor rotates the target at high speed using the principle of an induction motor. The filament is located in a cathode sleeve positioned opposite the target. When a voltage is applied from the generator, the filament irradiates the rotating anode with an electron beam corresponding to the voltage, and the rotating anode (anode rotor) generates radiation in a dose corresponding to the intensity of the electron beam.

[0024] Furthermore, the radiation source can be rotated by a horizontally extending rotation axis, allowing the radiation source to be switched between a horizontal orientation (for 3D imaging) and a vertical orientation (for supine imaging).

[0025] Furthermore, the radiation irradiation device 30 is rotatable relative to the main body 10, and is configured to allow adjustment of the direction of radiation irradiation to the subject (FPD 20) within a range greater than -90 degrees and less than 90 degrees (see also Figure 4, etc.). The rotation direction of the radiation irradiation device 30 may be along the left-right direction of the subject, or along the head-to-tail direction of the subject.

[0026] Furthermore, the main unit 10 also functions as a console (radiography control device). As shown in Figure 2, the main unit 10 includes an imaging control unit 40, an operation unit 41, a display unit 42, a storage unit 43, a communication unit 44, a drive unit 45, a battery 46, a connector 47, a charging unit 48, and the like.

[0027] The imaging control unit 40 is housed within the main unit 10 and includes a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc. In the imaging control unit 40, the CPU reads a program corresponding to the processing content from the ROM and loads it into the RAM. The imaging control unit 40 then works in cooperation with the loaded program to centrally control the operation of each part.

[0028] Furthermore, the imaging control unit 40 reconstructs a tomographic image based on multiple dynamic images and generates a dynamic tomographic image based on that tomographic image. The process for generating the dynamic tomographic image will be described later. The imaging control unit 40 corresponds to the "radiation image processing device" of the present invention.

[0029] The operation unit 41 has a touch panel or the like, in which transparent electrodes are arranged in a grid pattern to cover the surface of the display unit 42. The touch panel detects the position pressed by a finger or stylus and inputs that position information as operation information to the shooting control unit 40.

[0030] Furthermore, the control unit 41 is equipped with an exposure switch 41A for operating the radiation irradiation device 30. The exposure switch 41A is a switch for the user to instruct the radiation irradiation device 30 to perform radiation irradiation.

[0031] The display unit 42 is comprised of a monitor such as an LCD (Liquid Crystal Display) or a CRT (Cathode Ray Tube). The display unit 42 displays information according to the instructions of the display signals input from the shooting control unit 40.

[0032] The storage unit 43 is composed of non-volatile semiconductor memory, a hard disk, or the like. The storage unit 43 stores data such as various programs executed by the imaging control unit 40, parameters necessary for processing by the programs, or processing results.

[0033] Furthermore, the memory unit 43 is provided with a primary storage area (not shown) for temporarily storing radiation images transferred from the FPD 20. In addition, the memory unit 43 is provided with an image storage area (not shown) for storing radiation images transferred from the FPD 20 for a certain period of time in association with supplementary information.

[0034] The communication unit 44 transmits and receives data with the FPD 20 via wired or wireless communication. The communication unit 44 also transmits and receives data with external devices such as RIS and PACS via a communication network.

[0035] The drive unit 45 is a circuit that drives the tube of the radiation source in the radiation irradiation device. The drive unit 45 and the radiation source are connected via a cable.

[0036] The battery 46 supplies power to all parts of the main unit 10 and to the radiation source. The battery 46 can be charged externally via an AC cable.

[0037] The connector 47 is located inside the storage compartment and is electrically connected to the FPD 20 stored in the storage compartment.

[0038] The charging unit 48 charges the FPD 20 connected via the connector 47 using power supplied from the battery 46, based on control from the shooting control unit 40.

[0039] Next, the process for generating tomographic dynamic images will be explained. Figure 3 is a block diagram of the imaging control unit 40.

[0040] As shown in Figure 3, the imaging control unit 40 includes a phase alignment unit 410, a position alignment unit 420, a reconstruction unit 430, and a generation unit 440.

[0041] The phase alignment unit 410 performs phase alignment on each of the multiple motion images. Each of the multiple motion images is a motion image taken under conditions where the direction of radiation irradiation to the subject (object) is different from that of the other. In this embodiment, the multiple motion images include a first motion image and a second motion image.

[0042] For example, the first dynamic image is a dynamic image where the irradiation direction is in the first direction (D1 shown in Figure 4), which is perpendicular to the plane of the FPD20. The second dynamic image is a dynamic image where the irradiation direction is in the second direction (D2 shown in Figure 4), which is different from the first direction relative to the plane of the FPD20. In other words, the first dynamic image among the multiple dynamic images is a dynamic image acquired under conditions where the irradiation angle to the subject is different from that of the second dynamic image.

[0043] As shown in Figure 4, the difference in angle between the first direction D1 and the second direction D2 is in the range of greater than -90 degrees and less than 0 degrees, or greater than 0 degrees and less than +90 degrees. In other words, the absolute value of the difference between the illumination angle of the first dynamic image and the illumination angle of the second dynamic image is in the range of greater than 0 degrees and less than 90 degrees.

[0044] Multiple dynamic images are captured by rotating the radiation source of the radiation irradiation device 30 relative to the main unit 10.

[0045] Furthermore, the first dynamic image and the second dynamic image (multiple dynamic images) are each radiation images captured at different timings. For example, when capturing one of the first or second dynamic images, the radiation irradiation device 30 is set to have an irradiation direction corresponding to that one, and the image is taken. Then, when capturing the other of the first or second dynamic image, the radiation irradiation device 30 is set to have an irradiation direction corresponding to that other, and the image is taken. For example, in Figure 4, first, the radiation irradiation device 30 is set to have an irradiation direction of the first direction D1, and the image is taken. After that, the radiation irradiation device 30 is set to have an irradiation direction of the second direction D2, and the image is taken.

[0046] The phase alignment unit 410 performs the above phase alignment based on the phase change of signal values ​​indicating the respiratory state of the subject in each of the multiple dynamic images. The first and second dynamic images are images of the chest portion of the subject in a respiratory state. In the chest portion, by repeating a predetermined respiratory motion at a predetermined cycle, the signal values ​​indicating the movement of the lung fields and diaphragm in the dynamic image change over time in an oscillating manner, as shown in Figure 5.

[0047] However, since the first and second motion images are captured separately, the phase of the waveforms showing the time change of the signal value may be shifted. For example, in the example shown in Figure 5, the waveform of the second motion image is shifted by n frames relative to the waveform of the first motion image. n is any natural number.

[0048] Specifically, in the first motion image, frame t represents the first peak of the waveform, while in the second motion image, frame t+n represents the first peak of the waveform. t is any natural number.

[0049] The phase alignment unit 410 aligns the t+n frame of the second motion image with the t frame of the first motion image, thereby synchronizing the first and second motion images.

[0050] The alignment unit 420 aligns the multiple motion images (first motion image and second motion image) whose phase alignment has been performed by the phase alignment unit 410. Specifically, the alignment unit 420 performs alignment based on the region of interest set in the motion image.

[0051] The region of interest set in the dynamic image is the region that serves as the rotation center position for the tomographic image generated from multiple dynamic images, and is, for example, a region set by the user.

[0052] For example, the user sets the regions of interest for the first and second dynamic images via the control unit 41. For example, Figure 6 shows an example where the regions of interest are set to the lower central portion of the right lung in both the first and second dynamic images.

[0053] The reconstruction unit 430 reconstructs a tomographic image based on multiple dynamic images. Specifically, the reconstruction unit 430 reconstructs a tomographic image based on multiple dynamic images that have been phase-aligned by the phase-alignment unit 410 and alignment-aligned by the alignment unit 420.

[0054] Tomographic reconstruction is performed using methods such as FBP (filtered back projection), IR (iterative reconstruction), and shift-and-add.

[0055] Furthermore, the reconstruction unit 430 reconstructs a tomographic image for each frame image that constitutes the dynamic image. For example, in Figure 5, in addition to the tomographic image of frame t of the first dynamic image and frame t+n of the second dynamic image, multiple tomographic images are reconstructed in the order of phase-aligned frames, such as the tomographic image of frame t+1 of the first dynamic image and frame t+n+1 of the second dynamic image.

[0056] The generation unit 440 generates a tomographic dynamic image based on the tomographic image reconstructed by the reconstruction unit 430. Specifically, the generation unit 440 generates a tomographic dynamic image using multiple tomographic images reconstructed by the reconstruction unit 430.

[0057] The tomographic dynamic image generated by the generation unit 440 is displayed, for example, on the display unit 42. This allows the user to easily confirm the three-dimensional location of the abnormal area of ​​the subject based on the tomographic dynamic image.

[0058] Next, the processing flow by the imaging control unit 40 will be explained. Figure 7 is a flowchart showing an example of the operation of the tomographic dynamic image generation process by the imaging control unit 40. This control is executed as appropriate when the imaging control unit 40 receives an instruction to generate a tomographic dynamic image in the radiography system 1.

[0059] As shown in Figure 7, the imaging control unit 40 acquires a first motion image and a second motion image (step S101). After step S101, the imaging control unit 40 performs a phase alignment process to align the phases of the first motion image and the second motion image (step S102).

[0060] After step S102, the imaging control unit 40 performs alignment processing to align the phase-aligned first dynamic image and the second dynamic image (step S103). After step S103, the imaging control unit 40 reconstructs a tomographic image based on the phase-aligned and aligned first dynamic image and the second dynamic image (step S104).

[0061] After step S104, the imaging control unit 40 generates a tomographic dynamic image based on the reconstructed tomographic image (step S105). After step S105, this control ends.

[0062] According to this embodiment configured as described above, a tomographic image is reconstructed based on multiple dynamic images, and a dynamic tomographic image is generated based on the tomographic image. Therefore, when an abnormal area is found in the subject, it becomes easier to identify the three-dimensional location of the abnormal area. In other words, in this embodiment, the location of the abnormal area of ​​the subject can be accurately identified.

[0063] Furthermore, because the phase alignment of multiple dynamic images is performed, the synchronization of each dynamic image can be achieved. As a result, accurate tomographic dynamic images can be generated.

[0064] Furthermore, by aligning multiple dynamic images that have undergone phase synchronization, the reference position for the tomographic image can be made more precise. As a result, an accurate tomographic image can be reconstructed.

[0065] Furthermore, since alignment is performed based on the region of interest set in the dynamic image, even when the distance from the radiation irradiation device 30 to the FPD 20 cannot be kept constant when acquiring multiple dynamic images, for example, it becomes easier to align multiple dynamic images. As a result, it becomes easier to reconstruct an accurate tomographic image.

[0066] Furthermore, since a tomographic image is reconstructed for each frame image that makes up the dynamic image, a dynamic tomographic image can be generated from the multiple reconstructed tomographic images.

[0067] Furthermore, since each of the multiple dynamic images is a radiation image captured at a different time, it is not necessary to capture each of the multiple dynamic images simultaneously. Therefore, it is not necessary to install multiple radiation irradiation devices 30 in the radiation imaging system 1. As a result, it is possible to reconstruct a tomographic image while capturing each of the multiple dynamic images using conventional equipment.

[0068] Incidentally, in postoperative patients receiving intensive care, it is necessary to understand conditions such as emphysema, atelectasis, pneumonia, pleural effusion, and pneumothorax, and to provide appropriate treatment interventions for each. While CT is ideal for diagnosing these conditions, some patients, such as critically ill patients, may have difficulty being moved to the CT room, potentially preventing appropriate treatment.

[0069] In contrast, in this embodiment, since the imaging control unit 40 is installed in the mobile radiography system 1, even if there are patients who have difficulty moving to the CT room, the radiography system 1 can be moved to the patient's location to acquire dynamic images. This makes it easy to identify the three-dimensional location of the abnormal area in the patient by generating dynamic tomographic images. In other words, in this embodiment, appropriate treatment interventions can be provided even to patients who have difficulty moving to the CT room.

[0070] Although the above embodiment did not specifically mention processing after generating the tomographic dynamic image, for example, abnormal areas of the subject may be detected.

[0071] As shown in Figure 8, the imaging control unit 40 includes a detection unit 450 in addition to the configuration shown in Figure 3. The detection unit 450 detects abnormal areas of the subject based on the generated tomographic dynamic images.

[0072] Abnormal areas are detected, for example, by analyzing the intensity of the signal values ​​of each pixel in each frame image that makes up the dynamic image. For example, areas where the signal value falls below a predetermined threshold are detected as abnormal areas. Abnormal areas in the tomographic dynamic image may be processed to highlight the abnormal areas in the tomographic dynamic image displayed on the display unit 42.

[0073] This makes it easier to pinpoint the three-dimensional location of the abnormal area.

[0074] Furthermore, in the above embodiment, alignment was performed based on a region of interest set in the dynamic image, but the present invention is not limited thereto. For example, the alignment unit 420 may perform alignment based on the center coordinates of each frame image that constitutes the dynamic image.

[0075] In this case, the distance from the radiation irradiation device 30 to the FPD 20 is set to be the same for the first dynamic image and the second dynamic image.

[0076] This allows for easy alignment of multiple dynamic images without requiring user configuration.

[0077] Furthermore, although the above embodiment included a phase alignment unit 410 and a position alignment unit 420, the present invention is not limited thereto. For example, if it is possible to acquire dynamic images with phase alignment and position alignment performed by another device, the configuration may not include a phase alignment unit and a position alignment unit.

[0078] Furthermore, although the above embodiment involved aligning the phases of multiple motion images, the present invention is not limited thereto, and if the multiple motion images are synchronized, aligning the phases may not be necessary.

[0079] Furthermore, in the above embodiment, each of the multiple motion images was captured at a different timing, but the present invention is not limited to this, and each of the multiple images may be captured simultaneously.

[0080] Furthermore, although the above embodiment generated a tomographic dynamic image using two dynamic images, the present invention is not limited thereto, and a tomographic dynamic image may be generated using three or more dynamic images.

[0081] Furthermore, in the above embodiment, the radiography control device (radiation image processing device) was a radiography system 1 including a radiation irradiation device 30, but the present invention is not limited thereto. For example, a radiography control device separate from the radiation irradiation device may be located in an operation room separate from the radiography room where the radiation irradiation device is located.

[0082] Furthermore, the above embodiments are merely examples of how the present invention may be implemented, and the technical scope of the present invention should not be limited by them. In other words, the present invention can be implemented in various ways without departing from its gist or its main features. [Explanation of Symbols]

[0083] 1. Radiography System 2 PACS 3 HIS 4 RIS 10 Main unit 20 FPD 30 Radiation irradiation equipment 40. Image capture control unit 41 Operation section 41A Exposure Switch 42 Display section 43 Storage section 44 Communications Department 45 Drive unit 46 batteries 47 Connectors 48 Live parts 410 Phase alignment section 420 Alignment section 430 Reconstruction part 440 Generation part 450 Detection Unit

Claims

1. A radiographic image processing device capable of acquiring radiographic motion images, A reconstruction unit that reconstructs a tomographic image based on multiple dynamic images with different radiation irradiation directions applied to the subject, A generation unit that generates a tomographic dynamic image based on the aforementioned tomographic image, A radiation image processing device equipped with the following features.

2. The system further includes a phase alignment unit that performs phase alignment of each of the aforementioned multiple motion images. The reconstruction unit reconstructs the tomographic image based on the plurality of dynamic images that have been phase-aligned. The radiation image processing apparatus according to claim 1.

3. The phase alignment unit performs the phase alignment based on the phase change of the signal value indicating the breathing state of the subject in each of the plurality of motion images. The radiation image processing apparatus according to claim 2.

4. The system further includes a positioning unit that performs positioning of the plurality of dynamic images whose phases have been aligned, The reconstruction unit reconstructs the tomographic image based on the plurality of motion images that have been aligned. The radiation image processing apparatus according to claim 2.

5. The alignment unit performs the alignment based on the center coordinates of each frame image that constitutes the dynamic image. The radiation image processing apparatus according to claim 4.

6. The alignment unit performs the alignment based on the region of interest set in the dynamic image. The radiation image processing apparatus according to claim 4.

7. The reconstruction unit reconstructs the tomographic image for each frame image that constitutes the dynamic image. The radiation image processing apparatus according to claim 1.

8. The system further includes a detection unit that detects abnormal areas of the subject based on the generated tomographic dynamic image. The radiation image processing apparatus according to claim 1.

9. The first dynamic image among the plurality of dynamic images is a radiation image captured under conditions where the irradiation angle to the subject is different from that of the second dynamic image among the plurality of dynamic images. The radiation image processing apparatus according to claim 1.

10. The absolute value of the difference between the irradiation angle of the first dynamic image and the irradiation angle of the second dynamic image is greater than 0 degrees and less than 90 degrees. The radiation image processing apparatus according to claim 9.

11. Each of the aforementioned multiple motion images is a radiographic image taken at a different time. The radiation image processing apparatus according to claim 1.

12. The aforementioned radiation image processing device is installed in a mobile radiography system. The radiation image processing apparatus according to claim 1.

13. A program for a radiographic image processing device capable of acquiring radiographic motion images, On the computer, A reconstruction process that reconstructs a tomographic image based on multiple dynamic images with different radiation irradiation directions applied to the subject, A generation process that generates a dynamic tomographic image based on the aforementioned tomographic image, To execute program.

Images