Dynamic quality control device, dynamic quality control program, and dynamic quality control method

Abstract

To properly perform quality management of dynamic state imaging consisting of a plurality of frame images.SOLUTION: A dynamic state quality management device 2 for performing quality management about dynamic state imaging of imaging a dynamic state of a subject by irradiating the subject with radiation comprises: generation means which generates information about quality of the dynamic state by using at least two frame images among the plurality of frame images constituting a dynamic state image obtained by dynamic state imaging; and output means which outputs at least any of information indicating the linearity of information (dynamic state image) about the quality of the dynamic state imaging and information indicating the uniformity of the dynamic state image. Moreover, the generation means generates information about the quality of the dynamic state imaging on the basis of statistical information of the information about at least two frame images of the plurality of frame images.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a dynamic quality control device, a dynamic quality control program, and a dynamic quality control method. [Background technology]

[0002] Conventionally, various techniques have been proposed for quality control (QC) and quality assurance (QA) related to radiography of still images. For example, Patent Document 1 describes a radiographic image reading system that evaluates display dimensional accuracy, linearity, sharpness, etc. by performing calculations on image data obtained by radiography of a quality control phantom, determines whether the evaluation result for each evaluation item exceeds a threshold value, and determines whether each evaluation item passes or fails based on the results of the determination. Furthermore, Non-Patent Document 1 describes a quality control program that takes an image of a QC phantom, analyzes all test items including system sensitivity by automatic calculation, determines whether the value obtained by the calculation is within or outside the control range, and notifies the user of the result of the determination. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-283531 [Non-patent literature]

[0004] [Non-Patent Document 1] Tsuyoshi Haraguchi, "Development of CR Quality Control Program "SimpleCheck QC"", KONICA MINOLTA TECHNOLOGY REPORT, 2009, Vol. 6, pp. 69-72 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, various devices have been developed for performing dynamic radiography, which generates dynamic images made up of a plurality of frame images by sequentially irradiating radiation. As with still imaging, it is desirable for dynamic radiography to have a certain level of quality in order to prevent problems such as misdiagnosis by doctors, increased workload for technicians due to retakes, and increased radiation exposure for patients due to retakes. However, because dynamic radiography is a technology that has only recently been used in medical settings, there has not been sufficient research and development into QC and QA for dynamic radiography. For example, much of the regular QC after product delivery is performed manually and subjectively by engineers, but because dynamic photography provides a wider range of QC information than still photography, improvements in work efficiency are desired.

[0006] Furthermore, while still photography only captures one frame image, dynamic photography captures multiple frames in succession, which means that the radiation source cannot be cooled sufficiently due to the longer radiation exposure time, and the temperature of the radiation source may rise due to the trapped heat. As the temperature of the radiation source increases, the dose of radiation emitted by the radiation source increases or decreases over time (dose fluctuation), resulting in a problem in that the pixel values ​​read by the radiation detector based on the dose also increase or decrease.

[0007] In addition, dynamic imaging involves capturing multiple frame images at once, which reduces the patient's exposure dose. In order to reduce the radiation dose per frame, the dose per frame is lower than in still image photography. If the dose of radiation passing through the patient is low, the pixel values ​​read out by the radiation detector will contain relatively more noise, but in dynamic imaging, this is tolerated to a certain extent as a trade-off for reducing radiation exposure. In addition, even if a dynamic image contains noise that is considered undesirable for diagnosis using a still image (a single frame image), the dynamic image can be used for diagnosis as long as it is of a quality that allows, for example, dynamic observation or dynamic analysis to be performed. In other words, dynamic photography requires QC and QA from a different perspective than still photography (we found that the QC and QA required for dynamic photography are insufficient for still photography).

[0008] The present invention has been made in view of the above-mentioned problems, and has as its object to enable appropriate quality control of dynamic photography consisting of a plurality of frame images. [Means for solving the problem]

[0009] In order to solve the above problems, the dynamic quality control device according to the present invention comprises: A dynamic quality control device for performing quality control regarding dynamic radiography for capturing dynamic images of a subject by irradiating the subject with radiation, comprising: Among the plurality of frame images constituting the dynamic image obtained by the dynamic imaging, Between the middle and the end generating means for generating information about the quality of the dynamic imaging using at least two frame images; an output means for outputting information relating to the quality of the dynamic radiography; Equipped with The generating means is characterized in that it determines a frame image to be the object of quality control from among a plurality of frame images taken at a predetermined dose or less.

[0010] In addition, the dynamic quality control program according to the present invention includes: A dynamic quality control program for performing quality control regarding dynamic radiography for capturing dynamic images of a subject by irradiating the subject with radiation, comprising: On the computer, Among the plurality of frame images constituting the dynamic image obtained by the dynamic imaging, Between the middle and the endgenerating information about the quality of the dynamic imaging using at least two frame images; a process of outputting information relating to the quality of the dynamic imaging; Execute The generating process is characterized in that a frame image to be subject to quality control is selected from a plurality of frame images captured at a predetermined dose or less.

[0011] Further, the dynamic quality control method according to the present invention comprises: 1. A dynamic quality control method for performing quality control on dynamic radiography in which a dynamic state of a subject is captured by irradiating the subject with radiation, the method comprising: Among the plurality of frame images constituting the dynamic image obtained by the dynamic imaging, Between the middle and the end generating information about the quality of the dynamic imaging using at least two frame images; outputting information relating to the quality of the dynamic imaging; Equipped with The generating step is characterized in that a frame image to be subject to quality control is selected from a plurality of frame images captured at a predetermined dose or less. [Effects of the Invention]

[0012] According to the present invention, quality control of dynamic photography consisting of a plurality of frame images can be appropriately performed. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a block diagram illustrating an example of a radiation imaging system according to an embodiment of the present invention. [Figure 2] 2 is a transparent plan view showing the inside of an example of a quality control phantom used for quality control of the radiation imaging system of FIG. 1. FIG. [Figure 3] 2 is a block diagram showing a dynamic quality control device provided in the radiation imaging system of FIG. 1. FIG. [Figure 4] 4 is a flowchart showing the flow of dynamic quality control processing executed by the dynamic quality control device of FIG. 3. [Figure 5] 5 is a conceptual diagram showing the operation performed by the dynamic quality control device in the dynamic quality control process of FIG. 4. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the technical scope of the present invention is not limited to the following embodiments and illustrated examples.

[0015] <1. Radiography System> First, the schematic configuration of a radiation imaging system (hereinafter referred to as system 100) according to this embodiment will be described. FIG. 1 is a block diagram showing an example of a system 100, and FIG. 2 is a transparent plan view showing the inside of an example of a quality control phantom used for quality control of the system 100.

[0016] As shown in FIG. 1, the system 100 includes a radiation detector (hereinafter, detector 1) and a dynamic quality control device (hereinafter, control device 2). The system 100 according to this embodiment further includes a radiation generating device (hereinafter referred to as a generating device 3) and a console 4. The devices 1 to 4 are capable of communicating with each other via, for example, a communication network N (such as a local area network (LAN), a wide area network (WAN), or the Internet).

[0017] In addition, system 100 may be capable of communicating with a Hospital Information System (HIS), a Radiology Information System (RIS), a Picture Archiving and Communication System (PACS), a dynamic analysis device, etc., which are not shown.

[0018] [1-1. Radiation Generator] The generating device 3 includes a generator 31 , an irradiation instruction switch 32 , and a radiation source 33 . The generator 3 may be installed in the radiography room, or may be configured together with the console 4 and the like as a movable device called a medical cart.

[0019] When the irradiation instruction switch 32 is operated, the generator 31 applies a voltage to the radiation source 33 (tube) according to the preset imaging conditions (for example, conditions related to the subject S, such as the imaging region, imaging direction, and physique, and conditions related to the irradiation of radiation X, such as the tube voltage, tube current, irradiation time, and current-time product (mAs value)).

[0020] When a voltage is applied from the generator 31, the radiation source 33 generates radiation X (for example, X-rays) at a dose corresponding to the applied voltage. Furthermore, radiation source 33 can move in the X-axis direction (the direction of radiation X irradiation, the left-right direction in FIG. 1), the Y-axis direction perpendicular to the X-axis (the direction perpendicular to the paper surface in FIG. 1), and the Z-axis direction perpendicular to the X-axis and Y-axis (the up-down direction in FIG. 1), and can also rotate around a rotation axis parallel to the Y-axis and Z-axis to change the orientation of the radiation irradiation port.

[0021] The generator 3 is also configured to generate radiation X in a manner that corresponds to the form of the radiation image to be generated (a still image, a dynamic image made up of a plurality of frame images). In the case of a still image, each press of the irradiation instruction switch 32 irradiates the image with radiation X once. Do this. In the case of dynamic images, each time the irradiation instruction switch 32 is pressed, the irradiation of pulsed radiation X is repeated multiple times per predetermined time (for example, 15 times per second), or the irradiation of radiation X is continued for a predetermined time. That is, in the present invention, "sequential irradiation with radiation" includes continuous irradiation in which radiation is continuously irradiated, and pulse irradiation in which radiation is irradiated intermittently or not.

[0022] [1-2. Radiation detector] Although not shown in the figure, the detector 1 includes a sensor substrate on which radiation detection elements that generate an electric charge according to the dose when exposed to radiation X and switch elements that accumulate and release the electric charge are arranged two-dimensionally (in a matrix), a scanning circuit that switches each switch element on and off, a readout circuit (hereinafter referred to as ROIC) that reads out the amount of electric charge released from each pixel as a pixel value, a control unit that generates a radiographic image from the multiple pixel values ​​read out by the ROIC, and a communication unit that transmits data on the generated radiographic image and various signals to the outside and receives various information and signals.

[0023] The detector 1 stores and releases electric charges and reads out pixel values ​​in synchronization with the timing at which radiation X is irradiated from the generator 3, thereby generating a radiological image according to the dose of the irradiated radiation X. When a still image is to be generated, a radiographic image is generated only once per depression of the irradiation instruction switch 32. When a dynamic image is generated, frame images constituting the dynamic image are generated multiple times per predetermined time (for example, 15 times per second) for each depression of the irradiation instruction switch 32.

[0024] The detector 1 may be configured to store and transfer the generated dynamic image in the form of image data, or to display it in real time on a display device connected to the detector 1. An example of real-time display is fluoroscopy.

[0025] [1-3. Console] The console 4 sets various imaging conditions (tube voltage, tube current, irradiation time (mAs value), imaging region, imaging direction, etc.) for at least one of the detector 1 and the generator 3. The console 4 is composed of a PC, dedicated devices, etc. Furthermore, the console 4 sets the imaging conditions based on imaging order information acquired from other systems (such as an HIS or RIS) or on operations performed by a user (such as a technician).

[0026] [1-4. Dynamic quality control device] The management device 2 performs quality control regarding dynamic radiography. Here, "dynamic imaging" refers to imaging the dynamic state of the subject S by sequentially irradiating the subject S with radiation. Furthermore, "dynamic photography" includes video photography, but does not include taking still images while displaying a video. Furthermore, "dynamic images" include moving images, but do not include images obtained by capturing still images while displaying a moving image. Furthermore, the management device 2 targets for "quality control" at least a part of the series of operations (program execution) of the system 100 when performing dynamic imaging (for example, at least one of the operations of irradiating radiation X by the radiation generating device 3, generating dynamic images by the detector 1, transferring dynamic images between devices, analyzing by the dynamic analysis device, and saving dynamic images to a data storage device (cloud server, PACS, etc.)). In addition, "quality control" includes not only quality control through regular quality checks after product delivery, but also quality assurance at the time of product delivery.

[0027] The management device 2 is configured by a PC, a dedicated device, or the like. Although FIG. 1 illustrates the system 100 in which the management device 2 and the console 4 are provided separately, the management device 2 and the console 4 may be integrated. Furthermore, if the system 100 includes a dynamic analysis device, a PACS, or the like (not shown), the management device 2 may be integrated with these devices. The management device 2 will be described in detail later.

[0028] [1-5. Quality control phantom] In quality control using the management device 2, a quality control phantom (hereinafter referred to as phantom 5) may be used. That is, the system 100 may use the phantom 5 as the subject S. As shown in FIG. 2, the phantom 5 according to this embodiment has a rectangular substrate 51 (e.g., an acrylic plate) that is transparent to radiation, multiple types of evaluation members arranged on the substrate 51, and a sealing plate (e.g., an acrylic plate) (not shown) that is transparent to radiation and seals the evaluation members. The multiple types of evaluation members according to this embodiment are metal disks 52a to 52c, an edge pattern 53, a step wedge 54, and jitters 55a and 55b.

[0029] The metal disks 52a to 52c are made of circular metal plates. The metal constituting the metal disks 52a to 52c includes, for example, copper. The metal disks 52a to 52c are located at the three corners of the substrate 51, respectively.

[0030] The edge pattern 53 is made of a metal plate having sharp edges formed thereon. The metal forming the edge pattern 53 includes, for example, tungsten. The edge portion of the edge pattern 53 is slightly inclined with respect to one side of the substrate 51 .

[0031] The step wedge 54 has a plurality of (for example, four) rectangular metal plates 54a to 54d that differ from each other in thickness. The metal constituting each of the metal plates 54a to 54d includes, for example, copper. The metal plates 54a to 54d are arranged so that their thicknesses become thicker or thinner in stages.

[0032] The jitters 55a and 55b are made of rectangular metal (for example, copper) plates with straight edges. One of the long sides of the jitters 55a and 55b is aligned along one side of the substrate 51, and the other long side is aligned along another side of the substrate 51 that is perpendicular to the one side.

[0033] Although the phantom 5 having four types of evaluation members is exemplified here, the number of types of evaluation members that the phantom 5 has may be three or less, or may be five or more. Furthermore, although one phantom 5 is used for quality control here, a plurality of phantoms with different evaluation members disposed thereon may also be used for quality control. Furthermore, although a non-moving phantom 5 is used here, a dynamic phantom that performs a predetermined movement (for example, rotation, reciprocation, etc.) may also be used for quality control.

[0034] [1-6. Outline of operation of the radiography system] The system 100 configured in this manner operates as follows. First, the generator 3 irradiates radiation X to the subject S (the area to be diagnosed of the examinee) located between the radiation source 33 of the generator 3 and the detector 1, which are arranged opposite each other with a gap between them. The detector 1 then generates a radiological image (still image, dynamic image) showing the area to be diagnosed, and transmits the image data to at least one of the management device 2 and the console 4. When performing quality control, the generator 3 irradiates the phantom 5 located between the radiation source 33 and the detector 1 with radiation X, and the detector 1 generates a quality control image (still image, dynamic image: hereinafter referred to as QC image) containing the phantom 5, and transmits the image data to the management device 2. When the management device 2 receives the image data of the QC image, it executes dynamic quality control processing (described in detail later) and outputs information relating to the quality of dynamic imaging (described in detail later).

[0035] <2. Details of dynamic quality control equipment> Next, the management device 2 included in the system 100 will be described in detail. FIG. 3 is a block diagram showing the management device 2, FIG. 4 is a flowchart showing the flow of the dynamic quality control process executed by the management device 2, and FIG. 5 is a conceptual diagram showing the operations performed by the management device 2 in the dynamic quality control process.

[0036] [2-1. Configuration of dynamic quality control device] As shown in FIG. 3, the management device 2 includes a control unit 21, a storage unit 22, a communication unit 23, a display unit 24, and an operation unit 25. The units 21 to 25 are electrically connected by a bus or the like.

[0037] The control unit 21 is composed of a CPU (Central Processing Unit), RAM (Random Access Memory), and the like. The CPU of the control unit 21 reads out various programs stored in the memory unit 22, expands them in the RAM, executes various processes in accordance with the expanded programs, and centrally controls the operations of each unit of the management device 2.

[0038] The storage unit 22 is configured by a non-volatile memory, a hard disk, or the like. Furthermore, the storage unit 22 stores various programs (including a dynamic quality control program) executed by the control unit 21, parameters required for executing the programs, and the like. The storage unit 22 may be capable of storing image data of radiographic images acquired from other devices.

[0039] The communication unit 23 is composed of a communication module and the like. The communication unit 23 is configured to send and receive various signals and data to and from other devices (detector 1, console 4, etc.) connected by wire or wirelessly via a communication network N (LAN (Local Area Network), WAN (Wide Area Network), Internet, etc.).

[0040] The display unit 24 displays various screens used for diagnosis by the user. The display unit 24 is configured by, for example, an LCD (Liquid Crystal Display), an ELD (Electronic Luminescent Display), a CRT (Cathode Ray Tube), or the like. The display unit 24 displays a radiographic image or the like in accordance with the image signal received from the control unit 21 .

[0041] The operation unit 25 is an operation means configured to be operable by the user. The operation unit 25 includes a keyboard (cursor keys, numeric input keys, various function keys, etc.), a pointing device (mouse, etc.), a touch panel laminated on the surface of the display unit 24, etc. The operation unit 25 outputs a control signal to the control unit 21 in response to an operation performed by the user.

[0042] In addition, the management device 2 may not be equipped with a display unit 24 or an operation unit 25, and may be configured to receive control signals from an input device provided separately from the management device 2, for example, via a communication unit 23, or to output image signals to a display device (monitor) provided separately from the management device 2. Furthermore, if the other device (console 4, etc.) has a display unit and an operation unit, it may be configured to receive control signals from the operation unit of the other device and output image signals to the display unit of the other device (the display unit and operation unit may be shared with the other device).

[0043] [2-2. Operation of dynamic quality control device] The control unit 21 of the management device 2 configured as above executes a dynamic quality management process, for example, as shown in FIG. 4, when a predetermined condition is met. The specified conditions include, for example, that the power of the management device 2 has been turned on, that image data has been acquired from another device, that a specified control signal has been received from another device, and that a specified operation has been performed on the operation unit 25 (for example, an operation to start dynamic quality control processing, an operation to select the quality check to be performed, etc.).

[0044] (Image data acquisition) In this dynamic quality control process, the control unit 21 first executes an acquisition process (step S1). In this acquisition process, the control unit 21 acquires image data according to the content of the quality check that is about to be performed. For example, the control unit 21 acquires image data of a QC image obtained by dynamic imaging of the phantom 5, a QC image obtained by dynamic imaging of a phantom having one evaluation component corresponding to the content of the quality check to be performed, a QC image obtained by dynamic imaging of a dynamic phantom, or a solid image obtained by dynamic imaging without the subject S present. As described above, the phantom 5 according to this embodiment has a plurality of types of evaluation members, and therefore the QC image obtained by dynamic imaging of the phantom 5 can correspond to a plurality of types of quality checks. In the acquisition process according to this embodiment, the control unit 21 receives image data via the communication unit 23.

[0045] In this acquisition process, the control unit 21 may read the image data from the storage unit 22 or from a medium. In addition, in this acquisition process, the control unit 21 may acquire image data of an image (medical image) obtained by dynamic imaging of an actual subject as the subject S. Furthermore, when the dynamic quality control process is started in response to the acquisition of image data, it is not necessary to execute the acquisition process during the dynamic quality control process.

[0046] (Generation of information on the quality of dynamic photography) After acquiring the image data, the control unit 21 executes a generation process (step S2). In this generation process, the control unit 21 generates information regarding the quality of the dynamic photography (hereinafter referred to as quality information) using at least two frame images, including a first frame image and a second frame image, out of the multiple frame images that make up the dynamic image obtained by dynamic photography. This "quality information" includes at least one of information indicating the linearity of the dynamic image, information indicating the uniformity of the dynamic image, and information indicating the stability over time of pixel values ​​in the dynamic image. The quality information according to this embodiment includes information indicating the change over time of streaks in dynamic images, the presence or absence of lag, and the like. The information further includes at least one of information indicating the frame rate, information indicating the accuracy of the EI (Exposure Index), and information indicating the linearity of the EI. The "quality information" is output in the form of at least one of a numerical value indicating the quality, an image indicating the quality, and a quality judgment result (pass / fail, etc.).

[0047] In the generation process according to this embodiment, the control unit 21 first determines a frame image (hereinafter, target frame image F) that is to be the target of quality control (used to generate quality information) (step S21). Specifically, the control unit 21 first receives a selection of a predetermined frame image from the user via the operation unit 25. Then, the control unit 21 determines a target frame image F according to the selection received by the operation unit 25 from among the multiple frame images. For example, if the user selects at least one of the first and last frame images as the specified frame, the control unit 21 may be configured to determine at least two frame images excluding the selected frame image (e.g., the remaining frame images excluding at least one first frame image, the remaining frame images excluding at least one last frame image, the remaining frame images excluding at least one first and one last frame image, etc.) as the target frame images F.

[0048] Furthermore, if the user selects, for example, an intermediate frame image (e.g., the frame image with the serial number closest to the median) as the specified frame image, the control unit 21 may be configured to determine at least two frame images including the selected frame image (e.g., several frame images before and after the intermediate frame image, or several frame images after the intermediate frame image (including the intermediate to last frame image)) as the target frame image F. Furthermore, if the user selects, for example, the first half of all the frame images as the predetermined frame image, the control unit 21 may determine the first 30% of all the frame images as the target frame image F. Also, for example, the stability of the dose over time may be evaluated for all frames.

[0049] In this way, by narrowing down the frame images used to generate the quality information, it is possible to shorten the time required for subsequent processing and reduce the amount of image data. Furthermore, since the radiation X generated by the generator 3 becomes stable from the latter half of dynamic imaging, if the middle to last frame image is set as the target frame image F, various calculations for generating quality information can be performed stably.

[0050] In this generation process, the control unit 21 may be configured to determine, as the target frame image F, a frame image that satisfies a specific criterion from among a plurality of frame images. Specifically, the control unit 21 may be configured to determine the target frame image F from among the frame images captured at a predetermined dose or less (particularly, the one captured at the lowest dose). This is because the lower the dose, the more noticeable the contrast resolution, streaks, ROIC block irregularities, etc. Furthermore, if the specific criterion is, for example, "do not use the first frame image," then the first 10 to 30% of the image, excluding the first frame image, may be determined as the target frame image F. Furthermore, in this generation process, the control unit 21 may be configured to omit accepting the user's selection of a predetermined frame image, if necessary.

[0051] In the generation process according to this embodiment, the control unit 21 may be configured to set the frame image extracted every few frames as the target frame image F. Furthermore, in the generation process according to this embodiment, the control unit 21 may be configured to determine the number n of target frame images F before selecting a frame image. Specifically, the control unit 21 may be configured to determine the number n of frame images such that the sum (multiplied by n) of the doses required to obtain individual frame images reaches the dose required to obtain one still image, and generate quality information using the determined number n of target frame images F. This "dose required to obtain a frame image" may be an actually measured value or a set value. The actual measured value may be, for example, the dose generated by the generator 3 or the dose that reaches the panel. The set value may also be a standard dose that is determined in advance (for example, determined based on the irradiation conditions that are stored in advance in the storage unit 22 and set in the generator 3). Furthermore, the control unit 21 may be configured to determine the target frame image F automatically, or may be configured to determine it (manually) in response to an operation performed on the operation unit 25 by the user.

[0052] Furthermore, in the generation process according to this embodiment, the control unit 21 sets a partial region R in parallel with, or before or after, the determination of the frame image (step S22). For example, if the image data acquired in the above acquisition process is a QC image obtained by dynamic imaging of the phantom 5, the control unit 21 sets the area in the QC image that shows the evaluation component corresponding to the content of the quality check to be performed as the partial area R. Specifically, for example, when checking linearity or uniformity, the area in the QC image where the step wedge 54 appears is set as the partial area R. When checking the sharpness, the area in the QC image where the edge pattern 53 appears is set as the partial area R.

[0053] Furthermore, if the image data acquired in the above acquisition process is a QC image obtained by dynamic imaging of a dynamic phantom (to check the frame rate), the control unit 21 sets the area in the QC image in which the movable part is captured as partial area R.

[0054] The control unit 21 may be configured to set the partial area R automatically, or may be configured to set it (manually) in response to an operation performed on the operation unit 25 by the user. Furthermore, when a medical image is acquired by the above acquisition process, the control unit 21 may be configured to set, for example, a region of interest (ROI: Region of Interest, an area where a certain level of image quality is required) that a doctor focuses on, or an element that affects image quality (ROIC block, etc.), in a partial region R. Furthermore, if the above acquisition process acquires a QC image in which only one evaluation component is captured across the entire frame image, or if the acquisition process acquires a solid image and the control unit 21 has sufficient processing capacity (it is acceptable to perform calculations on all pixels of each frame), there is no need to set this partial area R.

[0055] In the dynamic quality control process according to this embodiment, after setting the partial region R, the control unit 21 generates quality information based on statistical information relating to at least two target frame images F among the plurality of frame images (step S23). The "statistical information" used in the generation process according to this embodiment is average information. The "average information" is information obtained by averaging information relating to at least two target frame images F.

[0056] The statistical information may be addition information, multiplication information, subtraction information, division information, or variance information. The "addition information" is information on at least two of the target frame images F. This is the information obtained by adding together each piece of information in F. "Multiplication information" is information obtained by multiplying information about one of at least two target frame images F by information about at least one of the remaining target frame images F. "Subtraction information" is information obtained by subtracting information about at least one of the remaining target frame images F from information about one of the at least two target frame images F. The "division information" is information obtained by dividing information relating to one of at least two target frame images F by information relating to at least one of the remaining target frame images F. The division information may also be the ratio of each piece of information. The "variance information" is the variance of each piece of information relating to at least two target frame images F.

[0057] Furthermore, the statistical information may be a combination of these. In this way, for example, a value calculated as (pixel value of second frame image - pixel value of first frame image) / pixel value of first frame image) can be used as statistical information. From this statistical information, it is possible to obtain information regarding changes over time in each piece of information related to the target frame image F.

[0058] In the dynamic quality management process according to this embodiment, the control unit 21 is configured to preliminarily set a partial region R. Therefore, in the generation process according to this embodiment, the control unit 21 generates quality information based on the partial region R in the first frame image and the region corresponding to the partial region R in the second frame image.

[0059] (Linearity of pixel values) For example, when generating quality information indicating the linearity of pixel values ​​read by detector 1 (acquiring a QC image in the acquisition process and setting the area in the acquired QC image where the step wedge 54 appears as partial area R), control unit 21 calculates average information (average value) of pixel values ​​obtained from partial area R in one of at least two target frame images F, and pixel values ​​obtained from a corresponding area located on the same coordinates as partial area R in the remaining target frame image F of at least two target frame images F, as shown in Fig. 5(a), for example. This reduces noise contained in the pixel values ​​in the area where the step wedge 54 appears. Then, based on the calculated average information, the control unit 21 calculates a value indicating the linearity between the dose of radiation (transmission dose) that has passed through each of the metal plates 54a to 54d of the step wedge 54 and the pixel values ​​of the area in which each of the metal plates 54a to 54d is imaged. Furthermore, if necessary, an image corresponding to the calculated value is generated, and it is determined whether the calculated value exhibits sufficient linearity.

[0060] In addition, if the size of the partial area R is relatively large (the number of pixels constituting the area in which the partial area R is captured is relatively large), the control unit 21 may reduce noise by calculating the average value of each pixel value constituting the partial area R of one target frame image F, rather than calculating statistical information about the information regarding multiple frame images.

[0061] Furthermore, if there is no phantom 5, the control unit 21 may be configured to acquire multiple solid images obtained by dynamic imaging under conditions in which the radiation dose generated by the generator 3 is different, instead of a frame image in which the phantom 5 is captured. The control unit 21 may generate information indicating the linearity between the dose when each solid image is dynamically captured and the pixel value of the corresponding solid image. In this case, the control unit 21 generates quality information using at least two frame images, but the statistical information This means that quality information is generated without using When generating information indicating linearity, the control unit 21 may extract one frame image from each solid image and use its pixel values, or may calculate the average value of the pixel values ​​of multiple frame images for each solid image and use the calculated value.

[0062] (Uniformity of pixel values) When generating quality information indicating the uniformity of pixel values ​​read by detector 1 (a QC image is acquired in the acquisition process, and the area in the acquired QC image where edge pattern 53 appears is set as partial area R), control unit 21 calculates average information (average value) of pixel values ​​obtained from partial area R in one of at least two target frame images F, and pixel values ​​obtained from a corresponding area located on the same coordinates as partial area R in the remaining target frame image F of at least two target frame images F, as shown in Fig. 5(b), for example. This reduces noise contained in the pixel values ​​in the area where edge pattern 53 appears. Then, based on the calculated average information, the control unit 21 calculates a value indicating the variation in pixel values ​​of the pixels that make up the area where the edge pattern 53 appears. Furthermore, if necessary, an image corresponding to the calculated value is generated, and it is determined whether or not the calculated value indicates sufficient uniformity.

[0063] The control unit 21 may generate information indicating noise contained in the pixel values ​​of the pixels that make up the partial region R, or information indicating the uniformity of the S / N ratio. In generating information indicating the uniformity of noise or S / N, the control unit 21 may calculate a value indicating the variation in noise or S / N for each frame image and average the calculated values. In this case, the control unit 21 generates quality information using at least two frame images, but does not use statistical information.

[0064] (Pixel value stability over time) When generating information quality information indicating the stability over time of pixel values ​​read by detector 1 (when an unexposed image is acquired in the acquisition process), control unit 21 generates information indicating the stability over time of pixel values ​​based on pixel values ​​obtained from a partial region R in one of at least two frame images and pixel values ​​obtained from a corresponding region located on the same coordinates as partial region R in the remaining frame image of at least two frame images. This "pixel value obtained from the partial (corresponding) region" may be the pixel value of one pixel in the partial (corresponding) region, or may be a representative value (average value, median value, etc.) of the pixel values ​​of multiple pixels in the partial (corresponding) region. Then, the control unit 21 calculates a value indicating the variation in the obtained pixel values. Furthermore, if necessary, an image corresponding to the calculated value is generated, and it is determined whether or not the calculated value indicates sufficient uniformity. In this case, the control unit 21 generates quality information using at least two frame images, but does not use statistical information.

[0065] (Changes in streaks over time) When generating quality information indicating the change over time of streaks in dynamic images generated by the detector 1 (an unexposed image is acquired in the acquisition process, and a long, narrow region extending along the extension direction (horizontal direction) of the streaks in the acquired unexposed image is set as the partial region R), the control unit 21 calculates the average value of the pixel values ​​of each pixel that makes up the partial region R for each frame image. Then, the fluctuation of each calculated average value is analyzed. For the analysis, for example, a value indicating the variation in the obtained pixel values ​​is calculated. In addition, if necessary, images can be generated according to the analysis results, and the analysis results can be used to We can then determine whether or not the information indicates a lack of functionality. In this case, the control unit 21 generates quality information using at least two frame images, but does not use statistical information. The control unit 21 may make the above determination multiple times while changing the location set as the partial region R, and may take the analysis result with the greatest variation as the quality information.

[0066] Incidentally, the presence or absence of streaks in one frame image can also be generated as quality information. In this case, the control unit 21 acquires a pixel value profile of one frame image in a direction perpendicular to the extension direction of the streaks, and determines the presence or absence of fluctuations in pixel values ​​using techniques such as frequency analysis, amplitude analysis, and SD analysis. In this case, it is possible to average the analysis results of the pixel value profiles of each frame image. In this case, the control unit 21 also generates quality information using at least two frame images, but does not use statistical information. The same method as that for checking the change over time in streaks and the presence or absence of streaks can also be used to detect the presence or absence of electromagnetic noise, disturbance streaks, etc.

[0067] (with or without lugs) When generating information indicating the presence or absence of lag (afterimage) as quality information, the control unit 21 uses one frame image and the previous frame image to identify an area on the frame image that is located on the same coordinates as the area in which the movable member of the dynamic phantom was captured in the previous frame image, and then calculates the ratio between the pixel values ​​of the pixels that make up the identified area and the pixel values ​​of the pixels surrounding the identified area. Furthermore, if necessary, an image corresponding to the calculated ratio is generated, and it is determined whether the calculated ratio indicates the presence of a sufficient amount of residual image. In this case, the control unit 21 also generates quality information using at least two frame images, but generates the quality information without using statistical information.

[0068] (frame rate) When at least one of information indicating the number of times per unit time the detector 1 repeats the accumulation and release of charge and the readout of pixel values ​​(reading frame rate) and information indicating the number of times per unit time the generator 3 repeats the irradiation of radiation X (irradiation frame rate) is generated as quality information (a QC image of a dynamic phantom is acquired in the acquisition process, and the area in the acquired QC image in which the movable member of the phantom is imaged is set as partial area R), the control unit 21 calculates at least one of the reading frame rate and the irradiation frame rate based on the difference between the position of the area in which the movable member is imaged in one target frame image F and the position of the area in which the movable member is imaged in the next target frame image F (the angle by which the movable member rotates in the cycle in which one frame is generated). In this case, the control unit 21 generates the quality information using at least two frame images, but does not use statistical information.

[0069] The control unit 21 may be configured to calculate, based on the difference in the position of the area in which the movable member is captured, at least one of information indicating the time (reading interval) from when the detector 1 starts to store or release charge or to read pixel values ​​until the next time the detector 1 starts the same operation, and information indicating the time (irradiation interval) from when the generator 3 starts to irradiate radiation X until the next time the generator 3 starts to irradiate radiation X.

[0070] (Dose stability over time) When generating information indicating the stability over time of the dose of radiation X generated by the radiation generating device 3 as quality information (the area in the QC image where the edge pattern 53 appears is set as the partial area R), the control unit 21 calculates the average value of the pixel values ​​(corresponding to the dose reaching each radiation detection element) of each pixel constituting the partial area R for each frame image, and calculates a value indicating the variation of each calculated average value. Put out. Furthermore, if necessary, an image corresponding to the calculated value is generated, and it is determined whether the calculated value shows sufficient stability over time. In this case, the control unit 21 also generates quality information using at least two frame images, but generates the quality information without using statistical information. In addition, in order to isolate the influence of the stability of pixel values ​​over time, the control unit 21 may acquire multiple frame images (captured by narrowing the irradiation field, etc.) each having an exposed area and an unexposed area, calculate the change in pixel values ​​over time using the unexposed area of ​​each frame image, and remove the calculated change in pixel values ​​over time from the change in dose over time calculated using the exposed area.

[0071] (EI accuracy) When generating information indicating the accuracy of EI as quality information (when multiple solid images are obtained by dynamic imaging under conditions where the radiation dose generated by the generator 3 is different), the control unit 21 calculates EI based on the radiation dose set for each imaging and the pixel values ​​of the corresponding solid images. Furthermore, if necessary, an image corresponding to the calculated EI is generated, and it is determined whether the calculated EI shows sufficient accuracy. In this case, if the calculation of accuracy for each dose is considered as one analysis, the control unit 21 will generate quality information using at least two frame images, but will generate the quality information without using statistical information.

[0072] (EI linearity) When generating information indicating the linearity of EI as quality information (when multiple solid images are obtained by dynamic imaging under conditions where the radiation dose generated by the generator 3 is different), the control unit 21 calculates EI based on the radiation dose set for each imaging and the pixel values ​​of the corresponding solid images. Then, the control unit 21 calculates a value indicating the linearity between the dose set for each imaging and the calculated EI for each imaging. Furthermore, if necessary, an image corresponding to the calculated value is generated, and it is determined whether the calculated value exhibits sufficient linearity. In this case, if the calculation of accuracy for each dose is considered as one analysis, the control unit 21 will generate quality information using at least two frame images, but will generate the quality information without using statistical information.

[0073] If quality information indicating that the required quality is not met is generated in the generation process described above, the control unit 21 may be configured to generate at least one of a confirmation item for the quality information indicating that the required quality is not met and a reason why the quality information indicating that the required quality is not met has been generated. The check items may be generated, for example, by referring to a table stored in advance in the memory unit 22 that shows the relationship between quality information indicating that the required quality is not met and the check items (possible causes), or by inputting the quality information indicating that the required quality is not met that has been generated this time into a trained model that has been machine-learned with the quality information as input and the check items as output.

[0074] Furthermore, before starting the generation process or at the beginning of the generation process, the control unit 21 may determine whether the dose required to obtain one frame image is less than a predetermined value (for example, the dose required to capture one still image), and if it determines that it is less than the predetermined value, generate quality information (if it determines that it is not less than the predetermined value (it is greater than or equal to the predetermined value), it may not perform subsequent processing).

[0075] The control unit 21 according to this embodiment executes the generation process described above. To make a means. The step of the control unit 21 executing the generation process corresponds to the step of generating information about the quality of dynamic imaging in the dynamic quality control method.

[0076] [Output of information on the quality of dynamic photography] After generating the quality information, the control unit 21 executes an output process (step S3). In this output process, the control unit 21 outputs the generated quality information. In the output process according to this embodiment, the control unit 21 causes the display unit 24 to display quality information (numerical values, images, judgment results, etc.). In this output process, the control unit 21 may transmit the quality information to another device (for example, the console 4, a mobile terminal, a printer, etc.) (to display or print on the other device). Furthermore, if the management device 2 is provided with a means for writing to a recording medium, the control unit 21 may write the quality information to the recording medium in this output process.

[0077] In this output process, the control unit 21 may output the quality information generated in the previous or previous generation process. In this case, the control unit 21 may be configured to output (for example, display in the form of a graph) the latest quality information and the past quality information together. In this way, it is possible to easily check whether any changes have occurred in the state of the system 100 between a quality check performed at a certain timing and a quality check performed at a later timing. In addition, in this output process, the control unit 21 may compare past quality information with the latest quality information, and output an alert if it determines that the quality has deteriorated by more than a predetermined amount.

[0078] Furthermore, if the above generation process generates quality information indicating that the required quality is not met, and at least one of a confirmation item for the quality information indicating that the required quality is not met and a reason why the quality information indicating that the required quality is not met is generated is generated, the control unit 21 may be configured to output at least one of the confirmation item and the reason in this output process.

[0079] Furthermore, if all of the quality information or a specified portion of the quality information generated in the above generation process indicates that the required quality is met, the control unit 21 may be configured to output in this output process that dynamic photography is possible. This prevents the user from taking dynamic images when there is a problem with at least a part of the system 100.

[0080] The control unit 21 according to this embodiment executes the output process described above. Furthermore, the step of the control unit 21 executing the output process corresponds to the step of outputting information about the quality of dynamic imaging in the dynamic quality control method.

[0081] <3. Effects> As described above, the management device 2 according to this embodiment or the system 100 including this management device 2 performs quality control regarding dynamic imaging, which captures the dynamic state of a subject S by sequentially irradiating the subject S with radiation X, and includes a control unit 21 (generation means, output means) that generates quality information using at least two of the multiple frame images that make up the dynamic image obtained by dynamic imaging, and outputs the quality information. Therefore, the management device 2 or the system 100 can appropriately manage the quality of dynamic photography consisting of a plurality of frame images.

[0082] <4.Other> It goes without saying that the present invention is not limited to the above-described embodiments, and can be modified as appropriate within the scope of the present invention.

[0083] For example, the management device 2 or system 100 in the above embodiment only performs quality control for dynamic photography, but the management device 2 or system 100 may also perform quality control for both still image photography and dynamic photography. Furthermore, the management device 2 in the above embodiment is configured to execute the generation process and the output process, but if the system 100 is equipped with a dynamic analysis device, the generation process may be executed by the dynamic analysis device, and the management device 2 may execute the output process based on the analysis results.

[0084] Furthermore, for example, in the above description, examples have been disclosed in which a hard disk or a semiconductor nonvolatile 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 also be used as other computer-readable media. Furthermore, carrier waves can also be used as a medium for providing data for the program according to the present invention via a communication line. [Explanation of symbols]

[0085] 100 Radiography System 1. Radiation detector 2 Dynamic quality control device 21 Control section 22 Memory section 23 Communications Department 24 Display 25 Control section 3. Radiation Generator 31 Generator 32 Irradiation instruction switch 33 Radiation source 4 Console 5. Phantom 51 PCB 52a~52c Metal disc 53 Edge Pattern 54 Step Wedge 54a~54d Metal plate 55a, 55b Jitter F Target frame image F N Communication Network R Partial area S Subject X radiation

Claims

1. A dynamic quality control device for performing quality control regarding dynamic radiography for capturing dynamic images of a subject by irradiating the subject with radiation, comprising: a generating means for generating information about the quality of the dynamic imaging using at least two frame images between the middle and the last of the plurality of frame images constituting the dynamic image obtained by the dynamic imaging; an output means for outputting information relating to the quality of the dynamic radiography; Equipped with The dynamic quality control device is characterized in that the generating means determines a frame image to be subject to quality control from a plurality of frame images taken at a predetermined dose or less.

2. A dynamic quality control device for performing quality control regarding dynamic radiography for capturing dynamic images of a subject by irradiating the subject with radiation, comprising: a generating means for generating information about quality of the dynamic imaging using at least two frame images among a plurality of frame images constituting the dynamic image obtained by the dynamic imaging; and an output means for outputting information about quality of the dynamic imaging. Equipped with The dynamic quality control device is characterized in that the generation means determines the number of frame images such that the sum of the doses required to obtain each frame image reaches the dose required to obtain one still image, and generates information regarding the quality of the dynamic imaging using the determined number of frame images.

3. A dynamic quality control device for performing quality control regarding dynamic radiography for capturing dynamic images of a subject by irradiating the subject with radiation, comprising: a generating means for generating information about the quality of the dynamic imaging using at least two frame images between the middle and the last of the plurality of frame images constituting the dynamic image obtained by the dynamic imaging; an output means for outputting information relating to the quality of the dynamic radiography; Equipped with A dynamic quality control device characterized in that the generating means generates information about the quality of the dynamic radiography when the dose required to obtain one frame image is less than a predetermined value.

4. The dynamic quality control device according to any one of claims 1 to 3, characterized in that the information relating to the quality of the dynamic imaging includes at least one of information indicating the linearity between the radiation dose and pixel values, and information indicating the variation in pixel values ​​of a partial region between at least two frame images.

5. The dynamic quality control device according to any one of claims 1 to 4, characterized in that the generation means generates information regarding the quality of the dynamic photography based on statistical information regarding at least two frame images among the plurality of frame images.

6. the at least two frame images include a first frame image and a second frame image; The dynamic quality control device of claim 5, wherein the generation means generates information regarding the quality of the dynamic photography based on a partial area in the first frame image and an area corresponding to the partial area in the second frame image.

7. The dynamic quality control device described in claim 5 or claim 6, characterized in that the statistical information is additive information obtained by adding information about at least two of the multiple frame images, multiplication information obtained by multiplying information, subtraction information obtained by subtracting information, division information obtained by dividing information, average information obtained by averaging information, or variance information.

8. 8. The dynamic quality management device according to claim 1, wherein the information relating to the quality of the dynamic image capture includes information indicating stability over time of pixel values ​​in the dynamic image.

9. A dynamic quality control program for performing quality control regarding dynamic radiography for capturing dynamic images of a subject by irradiating the subject with radiation, comprising: On the computer, generating information about the quality of the dynamic imaging using at least two frame images between the middle and the last of the multiple frame images constituting the dynamic image obtained by the dynamic imaging; a process of outputting information relating to the quality of the dynamic imaging; Execute The dynamic quality control program is characterized in that the generating process determines frame images to be subject to quality control from among a plurality of frame images taken at a predetermined dose or less.

10. A dynamic quality control program for performing quality control regarding dynamic radiography for capturing dynamic images of a subject by irradiating the subject with radiation, comprising: On the computer, generating information about the quality of the dynamic imaging using at least two frame images among a plurality of frame images constituting the dynamic image obtained by the dynamic imaging; a process of outputting information relating to the quality of the dynamic imaging; Execute A dynamic quality control program characterized in that the generating process determines the number of frame images such that the sum of the doses required to obtain individual frame images reaches the dose required to obtain one still image, and generates information regarding the quality of the dynamic imaging using the determined number of frame images.

11. A dynamic quality control program for performing quality control regarding dynamic radiography for capturing dynamic images of a subject by irradiating the subject with radiation, comprising: On the computer, generating information about the quality of the dynamic imaging using at least two frame images between the middle and the last of the multiple frame images constituting the dynamic image obtained by the dynamic imaging; a process of outputting information relating to the quality of the dynamic imaging; Execute A dynamic quality control program characterized in that the generating process generates information regarding the quality of the dynamic imaging when the dose required to obtain one frame image is less than a predetermined value.

12. The dynamic quality control program according to any one of claims 9 to 11, characterized in that the information relating to the quality of the dynamic imaging includes at least one of information indicating the linearity between the radiation dose and pixel values, and information indicating the variation in pixel values ​​of a partial region between at least two frame images.

13. A dynamic quality control program as described in any one of claims 9 to 12, characterized in that the computer is caused to execute a process of generating information regarding the quality of the dynamic photography based on statistical information regarding at least two frame images out of the plurality of frame images.

14. the at least two frame images include a first frame image and a second frame image; The dynamic quality control program of claim 13, characterized in that the computer is caused to execute a process of generating information regarding the quality of the dynamic photography based on a partial area in the first frame image and an area corresponding to the partial area in the second frame image.

15. The dynamic quality control program of claim 13 or claim 14, characterized in that the statistical information is additive information obtained by adding information about at least two of the plurality of frame images, multiplication information obtained by multiplication, subtraction information obtained by subtraction, division information obtained by division, average information obtained by averaging, or variance information.

16. 16. The dynamic quality control program according to claim 9, wherein the information relating to the quality of the dynamic imaging includes information indicating stability of pixel values ​​in the dynamic image over time.

17. 1. A dynamic quality control method for performing quality control on dynamic radiography in which a dynamic state of a subject is captured by irradiating the subject with radiation, the method comprising: generating information about the quality of the dynamic imaging using at least two frame images between the middle and the last of the multiple frame images constituting the dynamic image obtained by the dynamic imaging; outputting information relating to the quality of the dynamic imaging; Equipped with A dynamic quality control method characterized in that the generating step determines frame images to be subject to quality control from among a plurality of frame images taken at a predetermined dose or less.

18. 1. A dynamic quality control method for performing quality control on dynamic radiography in which a dynamic state of a subject is captured by irradiating the subject with radiation, the method comprising: generating information about the quality of the dynamic imaging using at least two frame images among a plurality of frame images constituting the dynamic image obtained by the dynamic imaging; outputting information relating to the quality of the dynamic imaging; Equipped with A dynamic quality control method characterized in that the generating step determines the number of frame images such that the sum of the doses required to obtain individual frame images reaches the dose required to obtain one still image, and generates information regarding the quality of the dynamic imaging using the determined number of frame images.

19. 1. A dynamic quality control method for performing quality control on dynamic radiography in which a dynamic state of a subject is captured by irradiating the subject with radiation, the method comprising: generating information about the quality of the dynamic imaging using at least two frame images between the middle and the last of the multiple frame images constituting the dynamic image obtained by the dynamic imaging; outputting information relating to the quality of the dynamic imaging; Equipped with A dynamic quality control method characterized in that the generating step generates information regarding the quality of the dynamic imaging when the dose required to obtain one frame image is less than a predetermined value.

20. 20. The dynamic quality control method according to claim 17, wherein the information relating to the quality of the dynamic imaging includes at least one of information indicating the linearity between the radiation dose and pixel values, and information indicating the variation in pixel values ​​of a partial region between at least two frame images.

21. A dynamic quality control method as described in any one of claims 17 to 20, characterized in that information regarding the quality of the dynamic photography is generated based on statistical information regarding at least two frame images out of the plurality of frame images.

22. the at least two frame images include a first frame image and a second frame image; The dynamic quality control method described in claim 21, characterized in that information regarding the quality of the dynamic photography is generated based on a partial area in the first frame image and an area corresponding to the partial area in the second frame image.

23. The dynamic quality control method described in claim 21 or claim 22, characterized in that the statistical information is additive information obtained by adding information about at least two of the multiple frame images, multiplication information obtained by multiplication, subtraction information obtained by subtraction, division information obtained by division, average information obtained by averaging, or variance information.

24. 24. The dynamic quality control method according to claim 17, wherein the information relating to the quality of the dynamic image capture includes information indicating stability over time of pixel values ​​of the dynamic image.

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