JP7484246B2 - Dynamic photography system - Google Patents

Description

The present invention relates to a dynamic imaging system.

Conventionally, dynamic imaging systems are known that repeatedly irradiate a subject with radiation such as X-rays at a predetermined time interval to obtain a dynamic image consisting of multiple images showing the subject's movements. In such dynamic imaging systems, the movement of the subject may cause the area of interest to go outside the image. For example, when dynamic imaging of the movement of the knee joint during a standing up motion is performed, the knee joint may go outside the image. When this happens, the movement of the area of interest cannot be captured from the captured image, resulting in inconveniences such as a decrease in imaging efficiency due to re-imaging and an increase in the subject's radiation exposure.

Therefore, for example, Japanese Patent Laid-Open No. 2003-233693 discloses a method of tracking a specific portion from an X-ray fluoroscopic image, and irradiating the subject with radiation when the specific portion is within a predetermined range.
Furthermore, Patent Document 2 describes a method of recognizing the position of a subject from an image including the subject captured by a camera, and setting the position of the collimator leaves based on the recognized position so that the center of the X-ray imaging area coincides with the center of the irradiation field.

JP 2018-75356 A JP 2012-147978 A

However, with the technology described in Patent Document 1, when a specific part moves and goes outside a predetermined range, frame images during that time are not captured, and the entire movement cannot be captured.
Furthermore, the technology described in Patent Document 2 can automatically adjust the irradiation field when capturing a still image, but cannot capture the movement of the region of interest.

The objective of the present invention is to provide a dynamic imaging system that can reliably capture the movement of an area of interest.

In order to solve the above problems, the present invention provides
A dynamic radiography system including an imaging means for performing dynamic radiography of a subject using a radiation irradiation device and a radiation detector, and acquiring a plurality of frame images obtained by the dynamic radiography ,
an acquisition means for acquiring position information of a region of interest of the subject during a series of photographing by the photographing means;
an adjustment unit that adjusts the position of the irradiation field of the radiation irradiation device and/or the position of the radiation detector based on the position information of the region of interest of the subject acquired by the acquisition unit;
Equipped with.

The present invention makes it possible to provide a dynamic imaging system that can reliably capture the movement of an area of interest.

1 is a diagram showing an overall configuration of a dynamic radiography system according to an embodiment of the present invention; FIG. 2 is a block diagram showing the functional configuration of the console of FIG. 1 . 3 is a flowchart showing a flow of a shooting control process executed by a control unit in FIG. 2 . 4 is a diagram showing an example of movement of a radiation detector by the imaging control process of FIG. 3; FIG.

Embodiments of the present invention will be described below with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.

[Configuration of Dynamic Radiography System 100]
First, the configuration of this embodiment will be described.
FIG. 1 is a diagram showing an example of the overall configuration of a dynamic imaging system 100 according to this embodiment.
The dynamic imaging system 100 is a device that performs dynamic imaging of the subject H by irradiating the subject H with radiation. Dynamic imaging refers to obtaining a plurality of images showing the dynamics of the subject H by repeatedly irradiating the subject H with pulsed radiation such as X-rays at a predetermined time interval (pulse irradiation) or continuously irradiating the subject H with a low dose rate without interruption (continuous irradiation). A series of images obtained by dynamic imaging is called a dynamic image. Each of the plurality of images that make up a dynamic image is called a frame image. Note that in this embodiment, a case where dynamic imaging is performed by pulse irradiation will be described as an example.

As shown in FIG. 1, the dynamic imaging system 100 is configured to include a radiation irradiation device 1, a radiation detection device 2, and a console 3. The radiation irradiation device 1 and the radiation detection device 2 constitute an imaging means. The console 3 is configured to be connected to the radiation irradiation device 1 and the radiation detection device 2 so as to be able to transmit and receive data.

The radiation irradiation device 1 includes a radiation source 11, a collimator 12, a camera 13, a holder 14, a moving mechanism 15, and the like.
The radiation source 11 is disposed at a position facing the radiation detection device 2 with a subject H (examinee) in between, and irradiates the subject H with radiation (X-rays) under the control of the console 3 .

The collimator 12 has an opening provided on the radiation irradiation side of the radiation source 11, and blocks the radiation irradiated from the radiation source 11 by opening and closing the opening under the control of the console 3, thereby forming a rectangular irradiation field.

The camera 13 is provided near the collimator 12, and captures an image of the subject H according to the control of the console 3, and outputs the image to the console 3. A visible light camera, an infrared camera, or the like can be used as the camera 13.

The holding unit 14 holds the radiation source 11, collimator 12, and camera 13 together so that they can be raised and lowered (moved in the Y direction (body axis direction)) from the ceiling C.

The moving mechanism 15 includes, for example, a motor, and moves the radiation irradiation device 1 in the X direction along a rail 15b extending in the X direction perpendicular to the Z direction, which is the radiation irradiation direction, and the Y direction, according to the control of the console 3, and moves the rail 15b and the radiation irradiation device 1 together in the Z direction along a rail 15a extending in the Z direction provided on the ceiling C. The moving mechanism 15 also raises and lowers the holding unit 14 in the Y direction according to the control of the console 3.

The radiation detection device 2 is configured to include a support 21, a detector holding section 22, a moving mechanism 23, a radiation detector P, and the like.
The detector holding part 22 is configured to be movable in the X and Y directions, and holds the radiation detector P so that it can move in the X and Y directions.

The movement mechanism 23 includes, for example, a motor, and, under the control of the console 3, moves the detector holding part 22 in the X direction along a guide 23a extending in the X direction, and moves the guide 23a and the detector holding part 22 together in the Y direction along a guide (not shown) that is provided on the support 21 and extends in the Y direction.

The radiation detector P is composed of an FPD (Flat Panel Detector) or the like. The radiation detector P has, for example, a glass substrate or the like, and a plurality of detection elements (pixels) are arranged in a matrix at predetermined positions on the substrate, which detect radiation (X-rays) irradiated from the radiation irradiation device 1 and transmitted through at least the subject H according to its intensity, convert the detected radiation into an electrical signal, and store it. Each pixel is composed of a switching unit such as a TFT (Thin Film Transistor). The radiation detector P controls the switching unit of each pixel based on the image reading conditions input from the console 3, switches the reading of the electrical signal stored in each pixel, and acquires image data (frame image) by reading the electrical signal stored in each pixel. The radiation detector P then outputs the acquired image data to the console 3.

The console 3 outputs radiation irradiation conditions to the radiation irradiation device 1 and image reading conditions to the radiation detection device 2 , and controls the radiation imaging operation by the radiation irradiation device 1 and the radiation image reading operation by the radiation detection device 2 .
As shown in FIG. 2, the console 3 includes a control unit 31, a storage unit 32, an operation unit 33, a display unit , and a communication unit , and each unit is connected to each other via a bus .

The control unit 31 is composed of a CPU (Central Processing Unit), RAM (Random Access Memory), etc. In response to the operation of the operation unit 33, the CPU of the control unit 31 reads out the system program and various processing programs stored in the storage unit 32 and expands them into the RAM, and in accordance with the expanded programs, performs centralized control of the operation of each part of the console 3 and the operation of the radiation irradiation device 1 and the radiation detection device 2. For example, the control unit 31 functions as an acquisition unit and an adjustment unit by executing the imaging control process described below.

The storage unit 32 is configured with a non-volatile semiconductor memory, a hard disk, etc. The storage unit 32 stores various programs executed by the control unit 31, parameters required for executing processes by the programs, data such as processing results, etc. The various programs are stored in the form of readable program codes, and the control unit 31 sequentially executes operations in accordance with the program codes.
The storage unit 32 also stores dynamic images acquired by imaging in association with patient information and examination information.

The operation unit 33 is configured with a keyboard equipped with cursor keys, numeric input keys, and various function keys, etc., and a pointing device such as a mouse, and outputs instruction signals input by key operations on the keyboard or mouse operations to the control unit 31. The operation unit 33 may also be equipped with a touch panel on the display screen of the display unit 34, in which case it outputs instruction signals input via the touch panel to the control unit 31. Furthermore, the operation unit 33 is equipped with adjustment keys for adjusting the positions of the radiation source 11 of the radiation irradiation device 1 and the radiation detector P of the radiation detection device 2, and an exposure switch for instructing the radiation irradiation device 1 to perform dynamic imaging.

The display unit 34 is composed of a monitor such as an LCD (Liquid Crystal Display) or CRT (Cathode Ray Tube), and displays input instructions and data from the operation unit 33 according to the instructions of the display signal input from the control unit 31.

The communication unit 35 has an interface for transmitting and receiving data to and from the radiation irradiation device 1 and the radiation detection device 2. Note that communication between the console 3 and the radiation irradiation device 1 and the radiation detection device 2 may be wired communication or wireless communication.

[Operation of Dynamic Imaging System 100]
Next, the operation of the dynamic imaging system 100 will be described.
Conventionally, when a relatively large movement of a subject is captured in dynamic shooting, for example, as shown in the following example, the attention area may extend outside the image area of the frame image.
- When capturing a dynamic image of someone standing up from a seated position in a chair, the knees extend beyond the frame.
- When dynamic imaging of shoulder internal and external rotation is performed, the shoulder joint extends beyond the frame image.
- When taking dynamic images of the cervical vertebrae moving back and forth, the cervical vertebrae extend beyond the frame of the image.
When dynamic walking images are taken to observe changes in load on the ankle joint during walking, the ankle joint extends beyond the frame image.

If the area of interest falls outside the image area of the frame image, the entire movement of the area of interest cannot be captured, and the image must be retaken, which causes problems such as increased workload for the technician (reduced imaging efficiency) and increased radiation exposure for the subject.

In the dynamic imaging system 100, when an instruction to start dynamic imaging is given, the control unit 31 of the console 3 executes the imaging control process shown in FIG. 3, acquires position information of the area of interest of the subject H during dynamic imaging, and adjusts the irradiation field of the radiation irradiation device 1 and/or the position of the radiation detector P during dynamic imaging based on the acquired position information of the area of interest, thereby ensuring that the movement of the area of interest can be captured on the dynamic image. "During dynamic imaging" refers to the period from the start of one dynamic imaging session to the end of the dynamic imaging session.

Here, before dynamic imaging, the imaging operator first prepares for imaging. That is, the operator accepts input of patient information and examination information (examination date and time, imaging area, etc.) using the operation unit 33 of the console 3, loads a radiation detector P of a size that can image the area of interest of the subject H into the detector holding unit 22, and performs positioning. In positioning, for example, the subject H is placed between the radiation detector P and the radiation source 11, and the positions of the radiation source 11 and the radiation detector P are adjusted so that the center of the area of interest of the subject H faces the center of the radiation detector P (radiation entrance surface) and the center of the radiation source 11.

When preparation for imaging is complete, the person performing imaging operates the exposure switch to instruct the start of dynamic imaging and has the subject perform a specified action. When the start of dynamic imaging is instructed, the control unit 31 executes imaging control processing. The imaging control processing is executed by the control unit 31 in cooperation with a program stored in the ROM.

First, the control unit 31 causes the radiation irradiation device 1 and the radiation detection device 2 to start dynamic imaging and acquire the first frame image (step S1).

Next, the control unit 31 acquires position information of the attention area of the subject H (step S2).
For example, the control unit 31 may cause the camera 13 included in the radiation irradiation device 1 to capture an image, analyze the captured image to recognize the area of interest, and obtain position information (coordinates) of the area of interest. Alternatively, the control unit 31 may cause the radiation source 11 to irradiate radiation, obtain a captured image from the radiation detector P, analyze the captured image to recognize the area of interest, and obtain position information of the area of interest. Alternatively, the control unit 31 may analyze frame images captured during dynamic imaging to recognize the area of interest, and obtain position information of the area of interest.
Acquiring captured images for acquiring position information using the camera 13 has the advantage of quick response. On the other hand, acquiring captured images for acquiring position information by radiation imaging has the advantage that it is not necessary to provide the camera 13 in the dynamic imaging system 100 (no extra configuration is required). Acquiring position information of the region of interest based on frame images acquired in dynamic imaging further eliminates the need for imaging operations for acquiring position information.
The region of interest can be recognized from the photographed image or the frame image by, for example, machine learning, template matching, etc. It is assumed that the region of interest is determined in advance for each photographed part.

Next, the control unit 31 determines, based on the obtained position information of the attention area, whether or not the attention area will fall within the image area of a frame image to be captured subsequently (step S3).
The control unit 31 judges whether or not the region of interest will fall within the image area of a frame image to be captured subsequently, based on the acquired position information of the region of interest and the position and size of the set radiation detector P. It may also predict and judge whether or not the region of interest will fall within the image area of a frame image to be captured subsequently, using multiple pieces of position information acquired up to that point.

If it is determined that the area of interest will fall within the image area of a frame image to be captured subsequently (step S3; YES), the control unit 31 controls the radiation irradiation device 1 to adjust the irradiation field according to the position of the area of interest (step S4).

For example, the control unit 31 controls the collimator 12 of the radiation irradiation device 1 to adjust the position of the opening of the collimator 12 so that the center of the irradiation field (irradiation field area) in a frame image to be captured subsequently coincides with the center of the area of interest, and adjusts (narrows) the size of the opening of the collimator 12 depending on the size of the area of interest to a range where the area of interest fits within the irradiation field in the frame image to be captured.
By adjusting the opening position of the collimator 12 so that the center of the irradiation field and the center of the region of interest are aligned, for example, when the region outside the irradiation field of each captured frame image is removed, the position of the center of the region of interest can be fixed between frame images, thereby reducing the reader's reading burden, which is preferable. In addition, by adjusting the size of the opening of the collimator 12 according to the size of the region of interest, the amount of radiation exposure of the subject can be reduced, which is preferable.

If it is determined that the area of interest will not fall within the image area of a subsequently captured frame image (step S3; NO), the control unit 31 controls the radiation irradiation device 1 and the radiation detection device 2 to adjust the position of the radiation detector P and the irradiation field according to the position of the area of interest so that the area of interest falls within the irradiation field in a subsequently captured frame image (step S5).
For example, the control unit 31 controls the moving mechanism 23 of the radiation detection device 2 to move the detector holding unit 22 so that the center of the captured frame image and the center of the region of interest are aligned, thereby moving the position of the radiation detector P. In addition, the control unit 31 controls the moving mechanism 15 and/or the collimator 12 of the radiation irradiation device 1 to adjust the position of the radiation source 11 and the opening position of the collimator 12 so that the center of the irradiation field and the center of the region of interest in the captured frame image are aligned, and adjusts the size of the opening of the collimator 12 so that the region of interest fits within the irradiation field in the frame image.

Next, the control unit 31 causes the radiation irradiation device 1 and the radiation detection device 2 to capture the next frame image (step S6), and determines whether or not to end the dynamic imaging (step S7).
For example, when the number of captured frame images reaches a predetermined number, it is determined that dynamic image capture is to be ended.
When it is determined that dynamic imaging is to be continued (step S7; NO), the control unit 31 returns to step S2.
When it is determined that the dynamic imaging is to be ended (step S7; YES), the control unit 31 causes the radiation irradiation device 1 and the radiation detection device 2 to stop imaging (step S8), and ends the imaging control process.

According to the above-mentioned imaging control process, for example, when dynamic imaging is performed with a moving hand as the region of interest, as shown in FIG. 4, the radiation detector P can be moved in accordance with the movement of the hand during dynamic imaging.

As described above, according to the dynamic radiography system 100, the control unit 31 of the console 3 acquires position information of the area of interest of the subject H during dynamic radiography, and adjusts the position of the irradiation field and/or the radiation detector during dynamic radiography based on the acquired position information of the area of interest.
Therefore, it is possible to prevent the region of interest from going out of the irradiation field in the frame image, making it impossible to capture the entire movement of the region of interest, and therefore it is possible to reliably capture the movement of the region of interest. In addition, it is possible to suppress a decrease in imaging efficiency due to re-imaging and an increase in the radiation dose of the subject.

For example, based on the acquired positional information of the area of interest, the control unit 31 determines whether or not the area of interest will fall within the image area of a frame image to be captured subsequently in dynamic shooting, and if it determines that the area of interest will not fall within the image area, adjusts the position of the irradiation field and the radiation detector P according to the positional information of the area of interest.
Therefore, the area of interest can be adjusted to fall within the irradiation field area of the frame image, and the movement of the area of interest can be captured reliably.

For example, when the control unit 31 determines that the area of interest will fall within the image area of a frame image to be captured subsequently, it adjusts the position of the irradiation field without adjusting the position of the radiation detector P. Therefore, the irradiation field area can be narrowed to the extent that the area of interest falls within the irradiation field area of the frame image, and the radiation dose to which the subject H is exposed can be reduced.

In addition, for example, the control unit 31 adjusts the center of the attention area so that it is aligned with the center of the irradiation field. For example, when the area outside the irradiation field of each captured frame image is removed, the position of the attention area between frame images can be fixed, reducing the reading burden on the radiologist.

Note that the description in the above embodiment is a preferred example of the present invention and is not intended to be limiting.

For example, in the above embodiment, the adjustments in steps S2 to S5 are performed before capturing each frame image in dynamic photography. However, the adjustments may be performed after a predetermined number of frame images have been captured, and the interval at which the adjustments are performed is not particularly limited.

In the above embodiment, a determination is made based on the position information of the attention area obtained in step S2 as to whether or not the attention area will be included in the image area of a subsequently captured frame image (or whether or not it is likely to be excluded), and the position of the irradiation field and/or the radiation detector P is adjusted based on the determination result. However, a determination may also be made based on the position information of the attention area obtained in step S2 as to whether or not the attention area will be excluded from the image area of a subsequently captured frame image, and if it is likely to be excluded, an alarm may be issued or capture may be stopped.

In addition, in the above embodiment, the present invention has been described as being applied to a dynamic imaging system that captures images in an upright position, but it may also be applied to a video imaging system that captures images in a lying position.

For example, in the above explanation, a hard disk or a non-volatile semiconductor memory is used as a computer-readable medium for the program according to the present invention, but the present invention is not limited to this example. Portable recording media such as CD-ROMs can be used as other computer-readable media. Carrier waves can also be used as a medium for providing data for the program according to the present invention via a communication line.

In addition, the detailed configuration and operation of each device that constitutes the dynamic imaging system may be modified as appropriate without departing from the spirit and scope of the present invention.

Reference Signs List 100 Dynamic radiography system 1 Radiation irradiation device 11 Radiation source 12 Collimator 13 Camera 14 Holder 15 Movement mechanism 2 Radiation detection device 21 Support 22 Detector holder 23 Movement mechanism P Radiation detector 3 Console 31 Control unit 32 Memory unit 33 Operation unit 34 Display unit 35 Communication unit 36 Bus

Claims (5)

A dynamic radiography system including an imaging means for performing dynamic radiography of a subject using a radiation irradiation device and a radiation detector, and acquiring a plurality of frame images obtained by the dynamic radiography,
an acquisition means for acquiring position information of a region of interest of the subject during a series of photographing by the photographing means;
an adjustment unit that adjusts the position of the irradiation field of the radiation irradiation device and/or the position of the radiation detector based on the position information of the region of interest of the subject acquired by the acquisition unit;
A dynamic imaging system comprising: The dynamic imaging system according to claim 1, wherein the acquisition means acquires an image of the subject using the imaging means, and acquires position information of the area of interest by recognizing the area of interest from the acquired image. The dynamic imaging system according to claim 1, wherein the acquisition means acquires an image of the subject using a visible light camera or an infrared camera, and acquires position information of the area of interest by recognizing the area of interest from the acquired image. The dynamic radiography system according to any one of claims 1 to 3, wherein the adjustment means determines whether the area of interest will fall within the image area of a frame image to be captured subsequently in the radiographic dynamic radiography based on the position information of the area of interest acquired by the acquisition means, and if it determines that the area of interest will not fall within the image area of the frame image, adjusts the position of the irradiation field and/or the radiation detector in accordance with the position information of the area of interest. The dynamic imaging system according to claim 4, wherein the adjustment means adjusts the irradiation field without adjusting the position of the radiation detector when it is determined that the region of interest falls within the image region of the frame image.

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