JP6321267B2 - Image analysis apparatus and method, and program - Google Patents

Description

  The present invention relates to an image analysis apparatus, method, and program for analyzing a radiographic image obtained by photographing a subject.

  Conventionally, when a radiographic image of a subject is captured by radiation that has passed through the subject, especially when the subject is thick, the radiation is scattered within the subject, and the radiation acquired by this scattered radiation (hereinafter referred to as scattered radiation) There is a problem that the contrast of the image is lowered. For this reason, when capturing a radiation image, a scattered radiation removal grid (hereinafter simply referred to as a grid) is provided between the subject and the radiation detector so that the radiation detector for detecting the radiation and acquiring the radiation image is not irradiated with the scattered radiation. ) May be used for shooting. When imaging is performed using the grid, the radiation scattered by the subject is less likely to be applied to the radiation detector, so that the contrast of the radiation image can be improved.

  On the other hand, when photographing using a grid is performed, a striped pattern (grid stripe) corresponding to the grid is included in the radiographic image in addition to the subject image, so that the image becomes difficult to see. For this reason, the process which removes a grid stripe from a radiographic image with respect to the radiographic image image | photographed using the grid is known (refer patent documents 1-4). Grid stripes are generated when a stationary grid is used for stationary imaging, and grid stripes are generated in a radiographic image when a rocking grid that is used with rocking is used. do not do. Therefore, when an oscillating grid is used, a high-quality radiation image without grid stripes can be acquired without performing the grid stripe suppression process described above.

  By the way, the grid is configured such that lead or the like that does not transmit radiation and interspace materials such as aluminum and fiber that easily transmit radiation are alternately arranged at a fine lattice density of, for example, about 4.0 pieces / mm. Therefore, the mass is large. In portable imaging performed in a hospital room or the like, it is necessary to place a grid between a sleeping patient and a radiation detector. For this reason, the weight of the grid is a factor that increases the burden of work for the photographer to place the grid and the burden on the patient at the time of photographing. In the case of a convergent grid, density unevenness may occur in the radiation image due to the oblique insertion of radiation.

  For this reason, a process has been proposed in which a radiographic image is taken without using a grid, and an image quality improvement effect obtained by removing scattered radiation by the grid is applied to the radiographic image by image processing ( (See Patent Document 5). The technique of Patent Document 5 classifies the pixels of the subject image into body thicknesses corresponding to the image signals, calculates the total scattered ray distribution generated by the subject having each classified body thickness, and calculates this from the radiation image. By subtracting, a radiation image from which the scattered radiation component has been removed is obtained. According to the method of Patent Document 5, since a grid is not necessary at the time of photographing, it is possible to reduce the burden on the patient at the time of photographing and to prevent deterioration in image quality due to density unevenness and grid stripes.

  By the way, in a radiography system in which three types of radiographic images are acquired: a radiographic image captured using a stationary grid, a radiographic image captured using a bucky grid, and a radiographic image captured without a grid. When the process of removing the grid stripes is performed on all the radiographic images, the grid stripe suppression process is also performed on the radiographic image captured without the grid. On the other hand, when the scattered radiation suppression process is performed, the scattered radiation suppression process is also performed on the radiation image captured using the grid. As described above, when processing that is not necessary for a radiographic image is performed on the radiographic image, the image quality of the radiographic image is significantly reduced, and diagnosis cannot be performed efficiently.

  For this reason, in Patent Documents 1 and 2, for example, the grid is held by a frame-shaped holding portion in which a protruding portion is provided at a different position depending on the type of the grid, and the micro-device is positioned at the position of the device facing the protruding portion of the grid. Switches are provided, and these micro switches are configured so that the micro switches are turned on according to the type of grid. Patent Documents 1 and 2 propose a technique for discriminating the presence and type of a grid with such a configuration and performing image processing according to the presence and type of the grid. Patent Documents 1 and 2 propose a technique for determining the presence or weight of a grid by detecting a parameter amount that varies depending on a load applied to a motor that swings the grid.

JP 2003-260053 A Japanese Unexamined Patent Publication No. 2000-083951 JP 2003-008885 A Japanese Patent Laid-Open No. 06-014911 Japanese Patent Laid-Open No. 02-244881

  However, the techniques described in Patent Documents 1 and 2 may not be adopted depending on circumstances required depending on the photographing system and the photographing purpose. For this reason, in order to respond to various requests according to the photographing system and the photographing purpose, in addition to the techniques described in Patent Documents 1 and 2, a further technique for determining the type of grid is required.

  The present invention has been made in view of the above circumstances, and an image analysis apparatus, an image analysis method, and an image analysis apparatus for determining whether or not a radiographic image has been imaged by oscillating an oscillation imaging grid for removing scattered radiation. The purpose is to propose an image analysis program.

  An image analysis apparatus according to the present invention is irradiated with a radiation image acquisition unit that acquires a radiation image obtained by radiation imaging, and a specific position in an imaging region corresponding to the radiation image in a specific period including a radiographic image capturing period. A dose data acquisition unit that acquires dose data representing the amount of radiation in time series, a plurality of radiation absorbers, and a radiation transmissive body located between adjacent radiation absorbers at a specific position and radiography It is discriminated whether or not it has a first feature representing a variation in dose due to passing between the radiation source used for the radiation source, and a radiation image corresponding to the dose data discriminated to have the first feature is obtained. And a discriminating unit that discriminates that the image is a use image of a swinging grid that is captured by swinging a swinging shooting grid for removing scattered rays.

  An image analysis method according to the present invention is an image analysis method to be executed by an image analysis apparatus, and includes a radiological image acquisition step for acquiring a radiographic image obtained by radiography, and radiation in a specific period including a radiographic image capturing period. A dose data acquisition step for acquiring dose data representing the radiation dose irradiated to a specific position in the imaging region corresponding to the image in time series, and the dose data between a plurality of radiation absorbers and adjacent radiation absorbers It is determined whether or not the radiation transmitting body located at the first position has a first characteristic representing a variation in dose due to passage between the specific position and the radiation source used for radiography, and the dose data is the first A discriminating image for discriminating that a radiographic image determined to have the above-mentioned features is an image using a rocking grid photographed by rocking a rocking photographing grid for removing scattered radiation. And characterized in that it has a and-up.

  A radiographic image processing program according to the present invention causes a computer to execute the above method.

  The “imaging period” means a period that substantially contributes to the formation of an image signal corresponding to a radiographic image, among the periods in which the radiation image is to be imaged. For example, in a radiation detector in which pixels that accumulate charges according to the amount of incident radiation are arranged in a two-dimensional matrix, a period in which charges are accumulated in each pixel for forming a radiation image can be given.

  The “specific period” may be a period including at least a part of the photographing period. The “specific period” is set to a period longer than the required period for the grid radiation absorber to pass between the specific position and the radiation source at least twice. For example, a specific period is a period after the radiation dose in the dose data becomes equal to or greater than a threshold value capable of determining that radiation has been applied, and at least twice between the specific position and the radiation source It is preferable to set a period longer than a required period for the radiation absorber layer of the grid to pass. In this case, the required period is calculated from the assumed pitch of the radiation grid and the rocking speed of the grid.

  Further, the “first feature” is that a scattered radiation removal grid in which radiation absorbers and radiation transmission bodies each having a specific width are alternately arranged has a specific position on the detection surface of the radiation detector in the imaging region. This is a feature for identifying the movement between the radiation sources. The first feature is a dose that appears when a plurality of radiation absorbers and a radiation transmission body located between adjacent radiation absorbers pass between a specific position and a radiation source used for radiography. Any method may be used as long as it represents characteristics of data fluctuation.

  In the image analysis apparatus according to the present invention, the determination unit determines whether or not the dose data has the first feature with the feature that the dose data has an adjacent sine wave shape having a constant amplitude as a first feature. May be.

  The “adjacent sine wave shape with a constant amplitude of dose data” includes not only the case where the amplitude of the adjacent sine wave shape is strictly constant but also the case where the amplitude is substantially constant. Further, in the adjacent sine wave shapes, if the positive amplitude is constant and the negative amplitude is constant, the positive amplitude and the negative amplitude may be the same or different. . Further, the “sine wave shape” is not limited to a strict sine wave but may be a shape that can be regarded as a substantially sine wave shape.

  In addition, the determination unit may use any method capable of determining that the dose data has “a feature of having an adjacent sine wave shape with a constant amplitude”. For example, a curve fitted from a plurality of dose values of dose data is calculated, and the calculated curve has an adjacent sine wave shape with a constant amplitude compared to the calculated curve and an adjacent sine wave shape with a constant amplitude. It may be determined whether or not. In addition, as an adjacent sine wave shape having a constant amplitude used for comparison, the moving speed in the moving direction of the assumed bucky grid, the radiation absorption amount of the radiation transmitting body, the width in the moving direction of the radiation transmitting body, It is preferable to prepare a plurality of samples appropriately set in period and amplitude according to the radiation absorption amount of the radiation absorber and the width in the moving direction of the radiation absorber.

  Further, in the image analysis apparatus according to the present invention, the discriminating unit has a positive maximum value caused by the passage of the radiation transmitting body and a minimum value of zero or more caused by the passage of the radiation absorber with a certain interval between the dose data. It may be determined whether or not the dose data has the first feature with the feature of alternately having the first feature.

  Further, in the image analysis apparatus according to the present invention, the determination unit determines that the dose data is “a positive maximum value resulting from the passage of the radiation transmitting body at a certain interval and a minimum value of zero or more resulting from the passage of the radiation absorber”. Any method capable of determining having the “characteristic of alternately having values” may be used. For example, calculate a curve fitted from multiple dose values of dose data, detect local maxima and minima in time series, and determine whether positive maxima and minima of zero or more are repeated alternately It is preferable to do.

  Further, in the image analysis apparatus according to the present invention, the determination unit stops the radiographic image corresponding to the dose data determined not to have the first feature, and the stationary imaging grid for removing the scattered radiation. It is preferable to determine whether the image is a still grid use image photographed in this way or a grid non-use image photographed without using a grid for removing scattered radiation.

  “A grid-free image taken without using a grid for removing scattered radiation” refers to a oscillating and stationary imaging grid for removing scattered radiation between the radiation source and the radiation detector at the time of imaging. It means a radiographic image taken without radiography.

  In the image analysis device according to the present invention, the determination unit determines whether or not the radiation image has the second feature that the image includes a still shooting grid image, and is determined to have the second feature. The radiographic image is determined to be an image using a static grid, corresponds to the dose data determined not to have the first feature, and the radiographic image determined not to have the second feature is not grid-selected. It is preferable to determine that the image is a use image.

  The image analysis apparatus according to the present invention preferably further includes a grid stripe suppression unit that suppresses a frequency component corresponding to an image representing a still shooting grid included in the still grid use image from the still grid use image.

  Further, in the image analysis apparatus according to the present invention, a scattered radiation image indicating scattered radiation components at each position of the grid unused image is generated from the grid unused image, and the scattered radiation image is subtracted from the grid unused image for scattering. It is preferable to further include a scattered radiation suppressing unit that performs a line component suppressing process.

  Further, in the image analysis device according to the present invention, the discriminating unit uses the oscillating grid information indicating that the radiographic image is captured by oscillating the oscillating imaging grid in the imaging instruction information indicating the radiographic image capturing instruction. When the shooting instruction information includes the rocking grid information, the image using the rocking grid is determined based on the rocking grid information of the shooting instruction information, and the shooting instruction information When it is determined that the oscillating grid information is not included, the oscillating grid use image may be determined by determining whether the dose data has the first feature.

  The “imaging instruction information” is information transmitted from the doctors to the person in charge of imaging for an imaging instruction, and is information including information for specifying the imaging target and the image inspection performed on the imaging target. For example, the imaging instruction information includes basic information related to an imaging target such as a patient name, sex, and age, a radiographic imaging instruction, a range / direction to be imaged, and imaging conditions.

  In the image analysis apparatus according to the present invention, the determination unit may add determination information indicating whether the image is determined to be a rocking grid use image to the radiographic image as supplementary information.

  According to the present invention, it is possible to suitably determine whether or not a radiographic image is an image photographed by rocking a rocking photographing grid for removing scattered rays.

1 is a schematic block diagram showing a configuration of a radiographic imaging system to which a radiographic image processing apparatus according to an embodiment of the present invention is applied. The block diagram which shows an example of the whole structure of the electronic cassette concerning 1st Embodiment 1 is a schematic block diagram showing the configuration of a radiation image processing apparatus according to an embodiment of the present invention. Diagram showing time series graph showing dose data The figure for demonstrating the principle of this invention Schematic block diagram showing the configuration of the scattered radiation suppression unit The figure which shows the scattered radiation content distribution in the radiographic image of the chest The figure which shows the conversion coefficient computed in the case of showing the scattered-radiation content rate distribution shown in FIG. The flowchart which shows the process performed in 1st Embodiment. The flowchart which shows the process performed in 2nd Embodiment. The flowchart which shows the process performed in 3rd Embodiment

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, a schematic configuration of the entire radiographic image capturing system including the radiographic image processing apparatus of the present embodiment will be described. FIG. 1 shows a schematic configuration diagram that is an outline of the overall configuration of an example of the radiographic imaging system of the present exemplary embodiment. In the radiographic image capturing system 10 of the present embodiment, the electronic cassette 20 itself has a function of detecting radiation irradiation start (imaging start).

  The radiographic imaging system 10 according to the present exemplary embodiment is based on an instruction (imaging menu) input from an external system (for example, RIS: Radiology Information System) via the console 16, and a doctor or a radiographer. It has a function of taking a radiographic image by an operation such as the above.

  The radiographic image capturing system 10 of the present embodiment has a function of causing a doctor, a radiographer, or the like to interpret a radiographic image by displaying the captured radiographic image on the display 50 of the console 16 or the radiographic image interpretation device 18. Have.

  The radiographic imaging system 10 according to the present exemplary embodiment includes a radiation generation device 12, a radiographic image processing device 14, a console 16, a storage unit 17, a radiographic image interpretation device 18, and an electronic cassette 20.

  The radiation generator 12 includes a radiation irradiation control unit 22. The radiation irradiation control unit 22 has a function of irradiating the imaging target region of the subject 30 on the imaging table 32 with radiation X from the radiation source 22 </ b> A based on the control of the radiation control unit 62 of the radiation image processing apparatus 14. Yes.

  The radiation X transmitted through the subject 30 is applied to the electronic cassette 20 held by the holding unit 34 inside the imaging table 32. The electronic cassette 20 has a function of generating charges according to the dose of the radiation X that has passed through the subject 30, generating image information indicating a radiation image based on the generated charge amount, and outputting the image information. The electronic cassette 20 of this embodiment includes a radiation detector 26.

  Further, on the subject side of the radiation detector 26, a grid Gm and a grid Gs for preventing the radiation scattered by the subject 30 from entering the radiation detector 26 are provided in a freely removable manner. In the present embodiment, the grid Gm is a rocking shooting grid, and the grid Gs is a still shooting grid.

  In the present embodiment, image information indicating a radiographic image output from the electronic cassette 20 is input to the console 16 via the radiographic image processing device 14. The console 16 according to the present embodiment uses the radiographing device 12 and the electronic cassette 20 by using an imaging menu and various information acquired from an external system (RIS) or the like via wireless communication (LAN: Local Area Network). It has a function to perform control. In addition to the function of transmitting / receiving various types of information including image information of radiographic images to / from the radiographic image processing apparatus 14, the console 16 of the present embodiment transmits / receives various types of information to / from the electronic cassette 20. Has the function to perform.

  The console 16 of the present embodiment is configured as a server computer, and includes a control unit 40, a display driver 51, a display 50, an operation input detection unit 52, an operation panel 54, an I / O unit 56, and an I / F unit. 58.

  The control unit 40 has a function of controlling the operation of the entire console 16, and includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an HDD (Hard Disk). Drive: hard disk drive). The CPU has a function of controlling the operation of the entire console 16, and various programs including a control program used by the CPU are stored in advance in the ROM. The RAM has a function of temporarily storing various data, and the HDD has a function of storing and holding various data.

  The display driver 51 has a function of controlling display of various information on the display 50. The display 50 according to the present embodiment has a function of displaying an imaging menu, a captured radiographic image, and the like. The operation input detection unit 52 has a function of detecting an operation state with respect to the operation panel 54. The operation panel 54 is used by a doctor, a radiographer, or the like to input operation instructions related to radiographic image capturing. In the present embodiment, the operation panel 54 includes, for example, a touch panel, a touch pen, a plurality of keys, a mouse, and the like. When the operation panel 54 is configured as a touch panel, the display 50 may be provided with a touch panel function.

  The I / O unit 56 and the I / F unit 58 have a function of transmitting and receiving various types of information between the radiographic image processing apparatus 14 and the radiation generating apparatus 12 through wireless communication. Further, the I / O unit 56 and the I / F unit 58 have a function of transmitting and receiving various types of information such as image information to and from the electronic cassette 20 through wireless communication.

  The control unit 40, the display driver 51, the operation input detection unit 52, and the I / O unit 56 are connected to each other through a bus 59 such as a system bus or a control bus so that information can be exchanged. Therefore, the control unit 40 controls the display of various information on the display 50 via the display driver 51 and controls the transmission / reception of various information with the radiation generator 12 and the electronic cassette 20 via the I / F unit 58. Each can be done.

  The radiation image processing apparatus 14 according to the present embodiment has a function of controlling the radiation generation apparatus 12 and the electronic cassette 20 based on an instruction from the console 16, and the storage unit 17 of the radiation image received from the electronic cassette 20. And the function of controlling display on the display 50 of the console 16 and the display on the radiographic image interpretation device 18.

  The radiographic image processing apparatus 14 according to the present embodiment includes a system control unit 60, a radiation control unit 62, a panel control unit 64, and an I / F unit 68.

  The system control unit 60 has a function of controlling the entire radiographic image processing apparatus 14 and a function of controlling the radiographic image capturing system 10. The system control unit 60 includes a CPU, a ROM, a RAM, and an HDD. The CPU has a function of controlling operations of the entire radiographic image processing apparatus 14 and the radiographic image capturing system 10. Various programs including a control program used by the CPU are stored in advance in the ROM. The RAM has a function of temporarily storing various data. The HDD has a function of storing and holding various data. The radiation control unit 62 has a function of controlling the radiation irradiation control unit 22 of the radiation generator 12 based on an instruction from the console 16. The panel control unit 64 has a function of receiving information from the electronic cassette 20 wirelessly or by wire.

  The system control unit 60, the radiation control unit 62, and the panel control unit 64 are connected to each other via a bus 69 such as a system bus or a control bus so that information can be exchanged.

  The storage unit 17 has a function of storing captured radiographic images and information related to the radiographic images. An example of the storage unit 17 is an HDD.

  The radiographic image interpretation device 18 is a device having a function for a radiographer to interpret a captured radiographic image, and is not particularly limited, and examples thereof include a so-called interpretation viewer, console, and tablet terminal. The radiographic image interpretation device 18 of the present embodiment is configured as a personal computer, and, like the console 16 and the radiographic image processing device 14, a CPU, ROM, RAM, HDD, display driver, display 23, operation input detection. Unit, operation panel 24, I / O unit, and I / F unit. In FIG. 1, only the display 23 and the operation panel 24 are shown in the configuration, and other descriptions are omitted to avoid complicated description.

  Next, a schematic configuration of the electronic cassette 20 will be described. In the present embodiment, a case will be described in which the present invention is applied to an indirect conversion radiation detector 26 that once converts radiation such as X-rays into light and converts the converted light into electric charges. In the present embodiment, the electronic cassette 20 includes an indirect conversion type radiation detector 26. In FIG. 2, a scintillator that converts radiation into light is omitted.

  The radiation detector 26 includes a sensor unit 103 that receives light to generate electric charge, accumulates the generated electric charge, and a TFT switch 74 that is a switching element for reading out the electric charge accumulated in the sensor unit 103. A plurality of pixels 100 configured by the above are arranged in a matrix. In this embodiment mode, charges are generated in the sensor unit 103 by irradiation with light converted by the scintillator.

  A plurality of pixels 100 are arranged in a matrix in one direction (the gate wiring direction in FIG. 2) and the direction intersecting the gate wiring direction (the signal wiring direction in FIG. 2). In FIG. 2, the arrangement of the pixels 100 is simplified. For example, 1024 × 1024 pixels 100 are arranged in the gate wiring direction and the signal wiring direction.

  In the present embodiment, among the plurality of pixels 100, a radiation image capturing pixel 100A and a radiation detection pixel 100B are determined in advance. In FIG. 2, the radiation detection pixel 100 </ b> B is surrounded by a broken line. The radiation image capturing pixel 100A is used to detect radiation and generate an image indicated by the radiation. The pixel 100B for radiation detection is a pixel used for radiation detection for detecting the start of radiation irradiation and the like, and is a pixel that outputs charges even during the charge accumulation period (details will be described later).

  The radiation detector 26 includes a plurality of gate wirings 101 for turning on / off the TFT switch 74 and a plurality of signal wirings for reading out the electric charges accumulated in the sensor unit 103 on a substrate (not shown). 73 are provided to cross each other. In this embodiment, one signal wiring 73 is provided for each pixel column in one direction, and one gate wiring 101 is provided for each pixel column in the cross direction. For example, the pixel 100 is arranged in the gate wiring direction. When 1024 × 1024 are arranged in the signal wiring direction, 1024 signal wirings 73 and 1024 gate wirings 101 are provided.

  Further, the radiation detector 26 is provided with a common electrode wiring 95 in parallel with each signal wiring 73. The common electrode wiring 95 has one end and the other end connected in parallel, and one end connected to a bias power supply 110 that supplies a predetermined bias voltage. The sensor unit 103 is connected to the common electrode wiring 95, and a bias voltage is applied via the common electrode wiring 95.

  A control signal for switching each TFT switch 74 flows through the gate wiring 101. As described above, when the control signal flows to each gate wiring 101, each TFT switch 74 is switched.

  An electric signal corresponding to the electric charge accumulated in each pixel 100 flows through the signal wiring 73 in accordance with the switching state of the TFT switch 74 of each pixel 100. More specifically, an electric signal corresponding to the amount of charge accumulated by turning on any TFT switch 74 of the pixel 100 connected to the signal wiring 73 flows through each signal wiring 73.

  Each signal wiring 73 is connected to a signal detection circuit 105 that detects an electrical signal flowing out to each signal wiring 73. Each gate line 101 is connected to a scan signal control circuit 104 that outputs a control signal for turning on / off the TFT switch 74 to each gate line 101. In FIG. 2, the signal detection circuit 105 and the scan signal control circuit 104 are shown in a simplified form. However, for example, a plurality of signal detection circuits 105 and scan signal control circuits 104 are provided (for example, 256). The signal wiring 73 or the gate wiring 101 is connected every time. For example, when 1024 signal wirings 73 and 1024 gate wirings 101 are provided, four scan signal control circuits 104 are provided to connect 256 gate wirings 101, and four signal detection circuits 105 are also provided to 256 wirings. The signal wiring 73 is connected one by one.

  The signal detection circuit 105 includes a known amplification circuit for amplifying an input electric signal for each signal wiring 73. In the signal detection circuit 105, an electric signal input from each signal wiring 73 is amplified by an amplifier circuit and converted into a digital signal by an ADC (analog / digital converter).

  The signal detection circuit 105 and the scan signal control circuit 104 are subjected to predetermined processing such as noise removal on the digital signal converted by the signal detection circuit 105 to indicate signal detection timing to the signal detection circuit 105. A control unit 106 that outputs a control signal and outputs a control signal indicating the output timing of the scan signal to the scan signal control circuit 104 is connected.

  The control unit 106 includes a microcomputer, and includes a nonvolatile storage unit including a CPU (Central Processing Unit), ROM and RAM, flash memory, and the like. The control unit 106 performs control for radiographic imaging by executing a program stored in the ROM by the CPU. Further, the control unit 106 performs a process (interpolation process) of interpolating the image data of each radiation detection pixel 100B on the image data subjected to the predetermined process, and an image indicated by the irradiated radiation. Is generated. That is, the control unit 106 generates an image indicated by the irradiated radiation by interpolating the image data of each radiation detection pixel 100B based on the image data subjected to the predetermined processing.

  The electronic cassette 20 amplifies the electric signal (charge information) of the signal wiring 73 (in the case of FIG. 2, at least one of D2 and D3, for example, D2) to which the radiation detection pixel 100B is connected. Whether or not the radiation is irradiated depending on whether or not the value is greater than or equal to the threshold value TH1 detected by 120 and the control unit 106 compares the value of the digital signal converted by the signal detection circuit 105 with a predetermined threshold value TH1 for detection. It is comprised so that detection may be performed. That is, the electronic cassette 20 is configured to perform detection related to radiation irradiation without requiring a control signal from the outside (for example, the radiation image processing device 14). Note that detection of whether or not radiation has been emitted by the control unit 106 is not limited to comparison with a detection threshold value, and for example, detection may be performed based on preset conditions such as the number of detections.

  In the present embodiment, “detection” of an electric signal indicates sampling of the electric signal. Hereinafter, data representing a time-series electrical signal (pixel signal) monitored by the radiation detection pixel 100B is referred to as dose data. In the present embodiment, the radiation detection pixel 100B continues to detect the electrical signal (charge information) output from the radiation detection pixel 100B even after detecting the start of radiation irradiation. Although details will be described later, dose data for a specific period including the imaging period is acquired.

As long as radiation dose data can be acquired, any detection method and detection pixel having any configuration may be employed. For example, in order to monitor radiation dose data, the following configurations (1) to (6) are exemplified.
(1) A pixel arbitrarily selected from radiographic image capturing pixels (two-dimensional array) is designated as a dedicated pixel for radiation detection. In this case, the radiation image capturing pixel and the radiation detection pixel have the same shape.
(2) A pixel arbitrarily selected from pixels (two-dimensional array) for radiographic imaging is configured to be capable of detecting radiation. That is, some of the pixels are used for radiation image capturing and radiation detection. For example, the selected pixel has a configuration in which the sensor unit is divided into two, and the sensor unit is selectively used for radiographic image capturing and radiation detection. Further, for example, the selected pixel may be additionally provided with a TFT switch, and radiation may be detected based on the leakage current of the additionally provided TFT switch.
(3) A sensor dedicated to radiation detection is arbitrarily disposed between pixels (for example, a gap between pixels) of pixels for radiographic imaging (two-dimensional array).

In the above methods (2) and (3), the structure of the radiation detector used in these methods may be such that only selected pixels (selected gaps) have such a structure. , And the structure of the TFT switch may be repeatedly patterned so that only selected pixels can be extracted.
(4) The radiation image capturing pixels (two-dimensional array) and the gaps between them are general structures, and a detection means is provided separately. Examples of the detection method include detection of a bias current of a radiation detector, detection of a gate current, detection of a leak current, and the like.
(5) The radiographic imaging pixels (two-dimensional array) and their gaps have a general configuration, and a radiographic imaging control unit is used for detection without providing a separate detection means. May be. Examples of the detection method include leak current detection.

Any of the above methods (1) to (5) corresponds to a case where a sensor that generates an electric charge (electric signal) according to the dose of radiation emitted inside the radiation detector is provided. However, the present invention is not limited to this, and a sensor may be provided outside the radiation detector as shown in (6) below. In addition, when the sensor inside a radiation detector and the sensor outside a radiation detector are named generically, it is called a radiation sensor.
(6) A radiation detection sensor is provided outside the radiation detector. For example, a radiation detection sensor is provided on the bottom surface of a radiation detector that is not irradiated with radiation.

  In any of the above methods (1) to (6), radiation may be detected when the gate of the TFT switch is on, or radiation may be detected when the gate is off. It may be.

  Moreover, as a structure and arrangement | positioning of the radiation detector 26 of the electronic cassette 20 of this Embodiment, arbitrary structures are employable in the range which can acquire said dose data and the production | generation of image information.

  The control unit 40 of the console 16 has a function as an image analysis apparatus in addition to a function of controlling the operation of the entire console 16. The control unit 40 (image analysis device) executes an image analysis program according to an embodiment of the present invention with hardware such as a CPU, ROM, RAM, and HDD, thereby obtaining an image acquisition unit 41 as shown in FIG. It functions as a dose data acquisition unit 42, a discrimination unit 43, a grid stripe detection unit 45, a grid stripe suppression unit 46, a scattered radiation suppression unit 47, an image processing unit 48, a display control unit 49, and a storage unit 44.

  When the operation input detection unit 52 in the console 16 detects an operation input, the image acquisition unit 41 acquires a radiation image corresponding to the operation input. The radiographic image is an image obtained by performing interpolation processing by the control unit 106 on the image signal detected by the radiation detector 26 using the radiographic image capturing pixel 100A.

  The dose data acquisition unit 42 irradiates the position (specific position) of the radiation detection pixel 100B as shown in FIG. 2 in the imaging region corresponding to the radiographic image during the specific period including the radiographic image capturing period. Dose data representing the quantity in time series is acquired. The dose data at the time of radiography and the radiographic image (radiation image corresponding to the dose data) taken by the radiography are associated with each other and stored in the storage unit 17.

  The “specific period” is a period including at least a part of the photographing period. The “specific period” is set to a period longer than a required period for the grid radiation absorber to pass between the specific position and the radiation source at least twice. For example, a specific period is a period after the radiation dose in the dose data becomes equal to or greater than a threshold value capable of determining that radiation has been applied, and at least twice between the specific position and the radiation source It is preferable to calculate and set a period longer than the required period for the radiation absorber layer of the grid to pass through from the assumed pitch of the radiation grid and the rocking speed of the grid. In the present embodiment, dose data for a period from the start of radiographic image capturing t0 to the end of radiographing is detected by the radiation detection pixel 100B and stored in the storage unit 17, and from the storage unit 17 to the control unit 40. It is acquired by the dose data acquisition unit 42.

  The discriminating unit 43 determines that the dose data has passed between a plurality of radiation absorbers and a radiation transmission body located between adjacent radiation absorbers between a specific position and the radiation source used for radiation imaging. It is discriminated whether or not it has a first feature representing dose fluctuation, and a radiographic image corresponding to the dose data discriminated to have the first feature described later is shaken by a grid Gm for removing scattered radiation. It is determined that the image is a rocking grid use image photographed by moving.

  In addition, the determination unit 43 in the present embodiment uses a stationary grid in which a radiographic image corresponding to dose data determined not to have the first feature is captured with the grid Gs for removing scattered radiation stationary. It is determined that the image is one of grid-free images taken without using a grid for removing the scattered radiation.

  In addition, the determination unit 43 has a second feature that the radiation image includes a grid stripe (an image of a stationary grid) caused by the stationary grid based on the presence or absence of the grid stripe of the radiation image detected by the grid stripe detection unit 45 described later. The radiographic image determined to have the second feature is determined to be a static grid use image, and corresponds to the dose data determined to have no first feature. A radiographic image that is determined to have no second feature is determined to be a grid-free image.

  In addition, in the process of determining whether or not the image is a rocking grid use image, the determination unit 43 adds determination information indicating whether or not the image is determined as a rocking grid use image as supplementary information to the radiation image. After the process of determining whether or not the image is a rocking grid use image, each unit such as the determination unit 43, the grid stripe detection unit 45, the grid stripe suppression unit 46, the scattered radiation suppression unit 47, and the display control unit 49, By referring to the incidental information of the radiographic image as necessary, it is configured to discriminate between necessary processing and unnecessary processing for the image using the rocking grid.

  As described above, the determination unit 43 according to the present embodiment determines that the radiographic image having the first feature is the image using the rocking grid, and the radiographic image having the second feature is the image using the static grid. It discriminate | determines and the radiographic image which does not have both the 1st and 2nd characteristics is discriminate | determined from a grid non-use image. That is, the determination unit 43 determines whether or not the grid is used for the radiographic image and the type of grid used for the radiographic image based on the presence or absence of the first feature and the second feature of the radiographic image. Can do. The determination unit 43 determines whether or not the rocking grid use image is based on the presence or absence of the first feature (processing that determines whether or not the grid Gm is rocking when the radiation image is captured), and whether or not the second feature is present. The processing for determining the still grid use image may be performed in any order.

  Here, referring to FIG. 4 and FIG. 5, the dose data acquired by the radiation detection pixel 100 </ b> B when the radiation image is captured by the electronic cassette 20 having the above-described configuration, and the swing grid use image using the dose data. The concept of discrimination will be described.

  FIG. 4 shows an example of dose data acquired by the radiation detection pixel 100B. FIG. 4 is a time-series graph in which the horizontal axis represents the time axis and the vertical axis represents the pixel signal value. Since the electrical signal Di increases when irradiated with radiation and changes with time, it can be expressed as a function of time t. In the radiation detector 26 of the present embodiment, the start of radiation irradiation is detected depending on whether or not the electrical signal Di exceeds the detection threshold. In FIG. 4, dose data when radiation is applied in a grid-free state is f (t), dose data when a bucky grid is used is a function g (t), and dose data n (t that represents impact noise. ), Expressed as dose data m (t) representing electromagnetic wave noise from peripheral devices. FIG. 5 is a diagram for explaining the relationship between the grid Gm and the radiation detection pixel 100B.

  According to the analysis of the inventors of the present invention, as shown in FIG. 4, the dose data f (t) at the time of imaging when the stationary grid is used or when the grid is not used is It increases with the rising of the radiation source 22A from t0, and when the radiation source 22A is in a state capable of stable irradiation, after the amount of charge accumulated in the pixel 100B reaches a predetermined value, it has a characteristic of maintaining a substantially constant value. . The dose data n (t) representing the impact noise generated in the pixel 100B when an impact is applied to the radiation detector 26 shows a large peak immediately after the impact, and then gradually decreases in amplitude along the time axis. And positive and negative peaks are periodically repeated. It is also conceivable that electromagnetic wave noise from peripheral devices is detected by the radiation detector 26. Dose data m (t) representing such electromagnetic wave noise has a weak, substantially constant amplitude, and has a characteristic of periodically repeating a positive peak and a negative peak along the time axis.

  Here, as the inventors of the present invention proceed with analysis of dose data, the grid Gm used for radiography includes a plurality of radiation absorbers gma and a plurality of radiation transmission bodies gmb as shown in FIG. When the radiography is performed by swinging the grid Gm, the radiation absorber gma and the radiation transmission body gmb are alternately arranged between the pixel 100B and the radiation source 22A. Focused on passing. When radiation imaging is performed by swinging the grid Gm, the dose data monitored by the radiation detection pixel 100B is included in the position between the plurality of radiation absorbers gma and the adjacent radiation absorbers gma. It has been found that a characteristic (first characteristic) representing a variation in dose due to the radiation transmitting body gmb passing between the position (specific position) of the pixel 100B and the radiation source 22A appears. Depending on the required items, the material of the radiation absorber gma having the first radiation absorption rate with respect to the grid Gm and the radiation transmission member gmb having the second radiation absorption rate smaller than the first radiation absorption rate, The width and thickness are selected.

  5 will be described in detail. When the radiation X passes through the radiation transmitting body gmb according to the movement of the grid Gm in the direction of the arrow in FIG. 5, the radiation transmitting body has a thickness tb in the irradiation direction at t3 to t5. When the radiation dose according to the radiation absorption by gmb reaches the pixel 100B and the radiation X passes through the radiation absorber gma, the radiation absorption by the radiation absorber gma having the thickness ta in the irradiation direction is performed at t5-t7. When the radiation amount corresponding to the pixel 100B reaches the pixel 100B and the radiation X passes through the radiation transmitting body gmb, the radiation amount corresponding to the absorption of the radiation by the radiation transmitting body gmb having the thickness tb in the irradiation direction from t7 to t9. Reaches the pixel 100B, and when the radiation X passes through the radiation absorber gma, the radiation absorption by the radiation absorber gma having the thickness ta in the irradiation direction is performed from t9 to t11. Flip amount of radiation reaches the pixel 100B. As described above, the radiation absorber gma and the radiation transmission body gmb alternately and repeatedly pass through, whereby the dose data in the pixel 100B includes the dose value corresponding to the radiation absorption body gma and the dose value corresponding to the radiation transmission body gmb. The fluctuation | variation which goes back and forth alternately with the dose value corresponding to the radiation absorber gma is shown. The present invention uses the first feature as described above, and when the dose data has the first feature, the radiation image corresponding to the dose data is taken by swinging the rocking grid. It is determined that the image is a rocking grid use image.

  The first feature may be specified by any method. For example, the first feature can be regarded as the feature 1A or 1B as follows.

  (Feature 1A) The dose data g (t) has a substantially sinusoidal shape adjacent to each other with a constant amplitude.

  In the grid Gm, each radiation absorber gma has substantially the same width wa in the movement direction (arrow direction in FIG. 5), and each radiation transmission body gmb has substantially the same width wb in the movement direction (arrow direction in FIG. 5). In this case, the adjacent predetermined waveform having a constant positive amplitude and a constant negative amplitude is detected in the radiation detection pixel 100B by swinging the bucky grid. Each of the predetermined waveforms has a substantially sinusoidal shape because a time delay of the charge amount due to the response speed of the pixel 100B occurs with respect to the switching of the amount of radiation that arrives due to the swing of the bucky grid. In addition, the adjacent sine wave shapes may be the same in the positive direction and the negative direction as long as the positive direction amplitudes substantially match and the negative direction amplitudes substantially match. May be.

  In the substantially sinusoidal shape of one cycle in the dose data g (t), the value corresponding to the amplitude in the positive direction (Vmax and the center of the amplitude of the dose data g (t) (FIG. In the example of FIG. 4, the difference between g (t5)) and the radiation absorption amount of each radiation absorber gma becomes smaller, and the value corresponding to the amplitude in the negative direction (Vmin and the center of the amplitude of the dose data g (t)). Difference). In the substantially sinusoidal period C1, the period between two inflection points (points corresponding to the center of the amplitude of the dose data g (t)) adjacent in the time axis direction is the width of the radiation absorber gma. It is determined according to wa (or the width wb of the radiation transmitting body gmb) and the speed in the moving direction of the grid Gm. For example, the period between time t5 and time t7 and the period between time t9 and time t11 in FIG. 4 are determined according to the width wa of the radiation absorber gma and the moving speed of the grid Gm. Further, the period between the time t2 and the time t5 and the period between the time t7 and the time t9 in FIG. 4 are determined according to the width wb of the radiation transmitting body gmb and the moving speed of the grid Gm. Therefore, if the width wa of the radiation absorber gma, the width wb of the radiation transmission body gmb, and the speed in the moving direction of the grid Gm are known, it is possible to identify the position of the substantially sinusoidal period C1 and the center of the amplitude in the time axis direction. . Further, if the radiation absorption amount of the radiation absorber gma and the thickness in the irradiation direction and the radiation absorption amount of the radiation transmission body gmb and the thickness in the irradiation direction are known, the positive amplitude and negative direction of the sine wave shape are known. Amplitude can be specified. As a result, the substantially sine wave shape generated by the grid Gm can be specified.

  The discriminating unit 43 can employ any method for discriminating whether or not the grid Gm is rocked based on the above-described feature 1A. When the determination unit 43 determines whether or not the grid Gm is rocked by the feature 1A, it is possible to accurately determine the rocking grid use image using the dose data.

  For example, the determination unit 43 calculates an approximate curve that is fitted from a plurality of dose values of the dose data, and compares the calculated approximate curve with an adjacent sine wave having a constant amplitude, so that the calculated curve is adjacent to the constant amplitude. It is possible to discriminate the feature 1A by discriminating whether or not it has a sine wave shape. For example, the amplitude and period of adjacent sine wave samples having a constant amplitude used for comparison are the width wa of the radiation absorber gma, the width wb of the radiation transmission body gmb, and the moving direction of the grid Gm. What is necessary is just to identify from information, such as speed. In this case, the rocking grid use image can be determined more accurately. If there are a plurality of rocking shooting grids Gm that are supposed to be used, sine wave samples corresponding to the respective grids Gm are prepared, and each sample is compared with an approximate curve, so that the characteristic 1A is obtained. You may make it calculate.

  (Characteristic 1B) Corresponding to the change in the amount of charge accumulated in the pixel 100B according to the change in the radiation dose, the dose data g (t) is positive due to the passage of the radiation transmitting body at a certain interval. It alternately has a local maximum value Vmax and a local minimum value Vmin of zero or more resulting from the passage of the radiation absorber.

  The discriminating unit 43 can employ any method for discriminating the rocking grid use image based on the feature 1B as described above. When the discriminating unit 43 discriminates the rocking grid use image by the feature 1B, the rocking grid use image can be suitably discriminated by a relatively simple method using the dose data. For example, the determination unit 43 calculates an approximate curve fitted from a plurality of dose values of the dose data, and sets the positive maximum value Vmax resulting from the passage of the radiation transmitting body in time series and the zero resulting from the passage of the radiation absorbing body. The above minimum value Vmin is detected, and it can be determined whether or not the maximum value Vmax and the minimum value Vmin are alternately repeated. In addition, when the presence or absence of the rocking of the grid Gm is determined by the feature 1B, the rocking of the grid can be determined by distinguishing from the impact noise and electromagnetic wave noise in the dose data.

  Note that, in the grid Gm in the present embodiment, the thickness tb in the radiation direction of each radiation transmitting body gmb and the thickness ta in the radiation direction of each radiation absorbing body gma are the same, and each radiation transmitting body gmb The width wb in the movement direction and the thickness wa in the movement direction of each radiation absorber gma are the same.

  Returning to FIG. 3, the continuation will be described. The grid stripe detection unit 45 detects the presence or absence of grid stripes, which are stripe patterns resulting from the grid used at the time of imaging, in the radiographic image. Specifically, frequency analysis is performed on the radiographic image to obtain a frequency spectrum, and it is determined whether or not a peak exists in a certain frequency component in the frequency spectrum. Here, in the radiographic image acquired by performing imaging using the grid, the frequency spectrum is included because the moire generated by sampling of the radiographic image due to the periodic fringe and the periodic fringe due to the period of the grid is included. In, there are peaks in the frequency components corresponding to the grid period and moire. Therefore, the grid stripe detection unit 45 detects the presence or absence of grid stripes in the radiographic image by determining whether or not a peak exists in the obtained frequency spectrum.

  In addition, the grid stripe detection unit 45 adds determination information indicating whether or not the image is determined as a still grid use image to the radiographic image as supplementary information. Note that after the process of determining whether the image is a still grid use image, each unit such as the determination unit 43, the grid stripe detection unit 45, the grid stripe suppression unit 46, the scattered radiation suppression unit 47, and the display control unit 49 is necessary. In response to this, the supplementary information of the radiographic image is referred to, and a process necessary for the still grid use image and an unnecessary process are discriminated.

  The grid stripe suppression unit 46 performs a grid stripe suppression process for suppressing a frequency component corresponding to an image (grid stripe) representing a still shooting grid included in the still grid use image from the still grid use image. As the grid stripe suppression process, for example, a filtering process using a filter for reducing a frequency component corresponding to the grid stripe can be used.

  The scattered radiation suppression unit 47 generates a scattered radiation image indicating scattered radiation components at each position of the grid unused image from the grid unused image, and subtracts the scattered radiation image from the grid unused image to thereby perform a scattered radiation component suppression process. I do. FIG. 6 is a schematic block diagram showing the configuration of the scattered radiation suppressing unit 47. As illustrated in FIG. 6, the scattered radiation suppressing unit 47 acquires a virtual grid characteristic that is a virtual grid characteristic that is assumed to be used to remove scattered radiation when capturing a radiation image. 451, a scattering information acquisition unit 452 that acquires scattering component information representing the scattering component of radiation included in the radiation image, and the virtual grid characteristics acquired by the characteristic acquisition unit 451 and the scattering component information acquired by the scattering information acquisition unit 452 And a removal processing unit 453 that performs scattered radiation suppression processing of the radiation image acquired by the radiation detector 26.

  The characteristic acquisition unit 451 receives an operation input by the operator at the operation input detection unit 52 and acquires a virtual grid characteristic corresponding to the received operation input. In this embodiment, the virtual grid characteristics include the scattered radiation transmittance Ts for the virtual grid and the transmittance of the primary line that passes through the subject as the subject 30 and is directly irradiated to the radiation detector 26 (primary line). Transmittance) Tp. The scattered radiation transmittance Ts and the primary radiation transmittance Tp take values between 0 and 1.

  The characteristic acquisition unit 451 may acquire the virtual grid characteristic by directly receiving the values of the scattered radiation transmittance Ts and the primary radiation transmittance Tp, but in the present embodiment, the grid information representing the type of grid. The virtual grid characteristics, that is, the scattered radiation transmittance Ts and the primary radiation transmittance Tp are acquired by receiving at least one designation of information about the subject (subject information) and imaging conditions at the time of acquisition of the radiation image.

  Here, the grid information is information specifying the type of grid, such as grid ratio, grid density, convergence type or parallel type, convergence distance in the case of the convergence type, and interspace material (aluminum, fiber, bakelite, etc.). At least one of the following. Scattered ray transmittance Ts and primary ray transmittance Tp differ depending on the type of grid. For this reason, regarding the grid information, a table in which at least one of various types of grid information is associated with the virtual grid characteristics is stored in the storage unit 44.

  The subject information includes the types of subjects such as the chest, abdomen, and head. Here, at the time of radiographic image capturing, the type of grid to be used is generally determined according to the imaging region, and the scattered radiation transmittance Ts and the primary radiation transmittance Tp differ depending on the grid type. Therefore, regarding the subject information, a table in which various subject information and virtual grid characteristics are associated is stored in the storage unit 44.

  The imaging conditions include at least one of an imaging distance (SID) at the time of imaging, an imaging dose, a tube voltage, a source target and filter material, and a type of radiation detector used for imaging. Here, when a radiographic image is captured, the type of grid to be used is generally determined according to the imaging conditions, and the scattered radiation transmittance Ts and the primary radiation transmittance Tp differ depending on the grid type. For this reason, a table in which various shooting conditions and virtual grid characteristics are associated with each other is stored in the storage unit 44. Note that various imaging conditions are often determined according to the facility where the radiographic imaging system is installed. For this reason, when the shooting conditions at the time of actual shooting are unknown, the shooting conditions corresponding to the facility may be used.

  The characteristic acquisition unit 451 refers to the table stored in the storage unit 44, receives an operation input by the operator at the operation input detection unit 52, and obtains grid information, subject information, and object information obtained according to the received operation input. A virtual grid characteristic is acquired based on at least one of the imaging conditions. The grid information, subject information, and shooting conditions may be input directly from the input unit 9. Alternatively, a list of various grid information, various subject information, and various shooting conditions is displayed on the display 50, and at least one selection of grid information, subject information, and shooting conditions is received from the list, so that the grid information, subject information, and shooting conditions are received. May be input. Further, the imaging conditions may be acquired from the radiation control unit 62.

  When the imaging condition is an imaging dose, an acrylic model with a known thickness may be imaged together with the subject, and the imaging dose may be acquired based on the density of the acrylic model portion in the acquired radiation image. . In this case, a table in which the density of the acrylic model and the imaging dose are associated with each other is stored in the storage unit 44, and the imaging dose may be acquired by referring to this table based on the density of the acrylic model. In addition, when an unexposed area obtained by directly irradiating the radiation detector 26 with radiation is included in the radiographic image, an imaging dose may be acquired based on the density of the unexposed area. In this case, a table in which the density of the missing region and the imaging dose are associated with each other is stored in the storage unit 44, and the imaging dose may be acquired by referring to this table based on the density of the missing region. Further, an imaging dose may be measured using a dosimeter, and the measured imaging dose may be used as an imaging condition.

  In the present embodiment, the scattered radiation suppression process is performed by frequency-decomposing the radiation image as will be described later. In the present embodiment, the virtual grid characteristic is acquired for each of a plurality of frequency bands of a radiographic image obtained by frequency decomposition. For this reason, the virtual grid characteristic in the table is associated with each of a plurality of frequency bands.

  A table in which all of the grid information, subject information, and shooting conditions are associated with the virtual grid characteristics is stored in the storage unit 44, and the virtual grid characteristics are acquired based on all of the grid information, the subject information, and the shooting conditions. You may make it do. In this case, the table is at least a four-dimensional table in which various grid information, various subject information, various shooting conditions, and virtual grid characteristics are associated with each other.

  It should be noted that the exposure multiple that is the rate of increase of the irradiation dose that increases by using the grid, the contrast improvement coefficient that is the contrast ratio between when the grid is used and when it is not used, and the scattered X-rays of the primary X-ray transmittance The selectivity, which is the ratio to the transmittance, is a characteristic value that represents the characteristics of the grid. From these characteristic values, the scattered radiation transmittance Ts and the primary radiation transmittance Tp can be calculated. Therefore, the characteristic acquisition unit 451 calculates and acquires the virtual grid characteristics, that is, the scattered radiation transmittance Ts and the primary radiation transmittance Tp, by accepting at least one designation of the exposure multiple, the contrast improvement coefficient, and the selectivity. You may do it.

  In the present embodiment, the scattered radiation suppression unit 47 performs the scattered radiation suppression processing based on not only the virtual grid characteristics but also the scattered component information. For this reason, the scattering information acquisition unit 452 acquires scattering component information. In the present embodiment, for example, if the subject is the chest, the scattered component information indicates that the central portion of the radiographic image where the mediastinum exists has more scattered rays and the peripheral portion where the lung field exists has less scattered rays. The scattered radiation content distribution in the image is taken.

  The scattering information acquisition unit 452 acquires scattering component information, that is, scattered radiation content distribution, by analyzing a radiographic image acquired by imaging. The analysis of the radiographic image is performed based on irradiation field information, subject information, and imaging conditions at the time of radiographic image capturing.

  The irradiation field information is information representing an irradiation field distribution related to the position and size of the irradiation field included in the radiation image when imaging is performed using the irradiation field stop. The subject information is information on the position of the subject on the radiographic image, the distribution of the composition of the subject, the size of the subject, the thickness of the subject, etc. in addition to the types of subjects such as the chest, abdomen, and head described above. is there. Imaging conditions include irradiation dose at the time of imaging (tube current x irradiation time), tube voltage, imaging distance (total of distance from radiation source to subject and distance from subject to radiation detector), air gap amount (subject To the radiation detector) and the characteristics of the radiation detector. These irradiation field information, subject information, and imaging conditions are factors that determine the distribution of scattered radiation contained in the radiation image. For example, the size of the scattered radiation depends on the size of the irradiation field. The greater the thickness of the subject, the larger the number of scattered radiation. If air exists between the subject and the radiation detector, the scattered radiation decreases. Therefore, the scattered radiation content distribution can be obtained more accurately by using these pieces of information.

  The scattering information acquisition unit 452 calculates a primary ray image and a scattered ray image according to the following formulas (1) and (2) from the distribution T (x, y) of the subject thickness in the radiographic image acquired by imaging, Based on the calculated primary ray image and scattered ray image, the scattered ray content distribution S (x, y) is calculated based on the equation (3). The scattered radiation content distribution S (x, y) takes a value between 0 and 1.

Icp (x, y) = Io (x, y) × exp (−μ × T (x, y)) (1)
Ics (x, y) = Io (x, y) * Sσ (T (x, y)) (2)
S (x, y) = Ics (x, y) / (Ics (x, y) + Icp (x, y)) (3)
Here, (x, y) is the coordinates of the pixel position of the radiation image, Icp (x, y) is the primary line image at the pixel position (x, y), and Ics (x, y) is the pixel position (x, y). , Io (x, y) is the incident dose to the object surface at the pixel position (x, y), μ is the line attenuation coefficient of the object, and Sσ (T (x, y)) is the pixel position (x, y). This is a convolution kernel representing the scattering characteristic according to the subject thickness in y). Equation (1) is an equation based on a well-known exponential attenuation law, and Equation (2) is expressed in “JM Boon et al, An analytical model of the scattered radiation distribution in diagnostic radiolog, Med. Phys. 15 (5), Sep / It is an expression based on the technique described in “Octo 1988” (reference document 1). The incident dose Io (x, y) on the subject surface is canceled by division when calculating S (x, y) regardless of what value is defined. Any value can be used.

  The subject thickness distribution T (x, y) assumes that the luminance distribution in the radiographic image is substantially the same as the thickness distribution of the subject, and converts the pixel value of the radiographic image into a thickness by the linear attenuation coefficient value. It may be calculated by the following. Alternatively, the thickness of the subject may be measured using a sensor or the like, or approximated by a model such as a cube or an elliptic cylinder.

  Here, * in the formula (2) is an operator representing a convolution operation. In addition to the thickness of the subject, the nature of the kernel also changes depending on the distribution of the irradiation field, the distribution of the composition of the subject, the irradiation dose at the time of imaging, the tube voltage, the imaging distance, the air gap amount, and the characteristics of the radiation detector. To do. According to the technique described in Reference Document 1, scattered radiation can be approximated by convolution of a position spread function (point spread function, Sσ (T (x, y)) in equation (2)) with respect to the primary line. Note that Sσ (T (x, y)) can be obtained experimentally according to irradiation field information, subject information, imaging conditions, and the like.

  In the present embodiment, Sσ (T (x, y)) may be calculated based on the irradiation field information, subject information, and photographing conditions at the time of photographing, but various kinds of irradiation field information, various subject information, and various photographing conditions. And Sσ (T (x, y)) are stored in the storage unit 44, and based on irradiation field information, subject information, and shooting conditions at the time of shooting, this table is referred to and Sσ ( T (x, y)) may be obtained. Note that Sσ (T (x, y)) may be approximated by T (x, y).

  The removal processing unit 453 performs scattered radiation suppression processing by reducing frequency components in a frequency band that can be regarded as scattered radiation in the radiation image based on the virtual grid characteristics and the scattered component information. For this reason, the removal processing unit 453 frequency-decomposes the radiographic image to obtain frequency components for each of a plurality of frequency bands, and performs a process of reducing the gain of at least one frequency component. Are combined to obtain a radiation image that has been subjected to scattered radiation suppression processing. As a frequency decomposition method, a known arbitrary method such as a wavelet transform or a Fourier transform can be used in addition to a method of performing multiresolution conversion of a radiation image.

  The removal processing unit 453 converts the frequency component from the scattered radiation transmittance Ts and the primary radiation transmittance Tp, which are virtual grid characteristics, and the scattered radiation content distribution S (x, y). Is calculated by the following equation (4).

R (x, y) = S (x, y) × Ts + (1-S (x, y)) × Tp (4)
Since the scattered radiation transmittance Ts, the primary radiation transmittance Tp, and the scattered radiation content distribution S (x, y) are values between 0 and 1, the conversion coefficient R (x, y) is also between 0 and 1. It becomes the value of. The removal processing unit 453 calculates the conversion coefficient R (x, y) for each of a plurality of frequency bands.

  In the following description, the pixel value of the radiation image is I (x, y), the frequency component image obtained by frequency decomposition is I (x, y, r), and the frequency synthesis is I (x, y) = ΣrI ( x, y, r), a conversion coefficient for each frequency band is represented by R (x, y, r), and a scattered radiation transmittance and a primary radiation transmittance for each frequency band are represented by Ts (r) and Tp (r). Note that r represents a frequency band hierarchy, and the larger r, the lower the frequency. Therefore, I (x, y, r) is a frequency component image in a certain frequency band. The scattered radiation content distribution S (x, y) may be the value calculated for the radiation image as it is, but it may be acquired for each frequency band in the same manner as the scattered radiation transmittance Ts and the primary radiation transmittance Tp. Good.

  In the present embodiment, a conversion coefficient R (x, y, r) is calculated for each frequency component, and a corresponding frequency band conversion coefficient R (x, y) for the frequency component image I (x, y, r). , R) to convert the pixel value of the frequency component image I (x, y, r), and the frequency component image I (x, y, r) multiplied by the conversion coefficient R (x, y, r). ) (That is, I (x, y, r) × R (x, y, r)) is frequency-synthesized to obtain a processed radiation image I ′ (x, y). Therefore, the processing performed in the removal processing unit 453 is expressed by the following equation (5). Since the conversion coefficient R (x, y, r) is a value between 0 and 1, the frequency band conversion coefficient R (x, y, r) corresponding to the frequency component (x, y, r). ), The pixel value, that is, the gain at the pixel position (x, y) of the frequency component is reduced.

I '(x, y) = Σr {I (x, y, r) × R (x, y, r)}
= Σr {I (x, y, r) × (S (x, y) × Ts (r) + (1-S (x, y)) × Tp (r))} (5)
Here, in the present embodiment, the radiographic image is frequency-resolved into six frequency bands, and the scattered radiation transmittance Ts and the primary radiation transmittance Tp are acquired for the six frequency bands. In this case, the scattered radiation transmittance Ts and the primary radiation transmittance Tp are values represented by, for example, the following formula (6). In Equation (6), the value on the lower frequency band is shown on the right side.

Ts = {0.7, 0.7, 0.7, 0.7, 0.3, 0.2}
Tp = {0.7, 0.7, 0.7, 0.7, 0.7, 0.7} (6)
As shown in Expression (6), the scattered radiation transmittance Ts and the primary radiation transmittance Tp have the same value in the high frequency band (r = 1 to 4), but the low frequency band (r = 5 to 6). In, the scattered radiation transmittance Ts is a lower value. This is because the grid has a higher removal rate in the low frequency band where the frequency component of the scattered radiation is dominant, but the frequency dependence of the removal rate is small for the primary line.

  FIG. 7 is a diagram showing the scattered radiation content distribution S (x, y) in the radiographic image of the chest. In FIG. 7, the higher the scattered radiation content distribution S (x, y), the higher the luminance at each pixel position. It can be seen from FIG. 7 that in the chest image, the content of scattered radiation is high around the mediastinum and the lung field. FIG. 8 shows conversion coefficients calculated based on the equations (4) and (6) in the case of showing such a scattered radiation content distribution S (x, y). In FIG. 8, the lower the luminance, the smaller the value and the larger the pixel value. When FIG. 7 and FIG. 8 are compared, it can be seen that the value of the conversion coefficient is small around the mediastinum and the lung field where the content of scattered radiation is high. Therefore, in the processed radiographic image obtained by performing the processing shown in Expression (5) using the conversion coefficient calculated in this way, scattered radiation components are removed according to the type of grid assumed to be used. Is done.

  The removal processing unit 453 may remove scattered radiation from the radiation image as described below. First, assuming that frequency synthesis is represented by I (x, y) = ΣrI (x, y, r) as described above, the removal processing unit 453 converts the frequency component image I (x, y, r) into the following: Using equation (7), the scattered radiation content distribution S (x, y) is used to decompose into a scattered component Ics (x, y, r) and a primary component Icp (x, y, r).

Ics (x, y, r) = S (x, y) × I (x, y, r)
Icp (x, y, r) = (1-S (x, y)) × I (x, y, r) (7)
Further, the removal processing unit 453 uses the following formula (8) to calculate scattered rays that are virtual grid characteristics for each of the scattered component Ics (x, y, r) and the primary line component Icp (x, y, r). The image is converted by applying the transmittance Ts (r) and the primary ray transmittance Tp (r), and the converted scattering component Ics ′ (x, y, r) and the primary ray component Icp ′ (x, y, r) are converted. Is calculated.

Ics ′ (x, y, r) = Ics (x, y, r) × Ts (r) = S (x, y) × I (x, y, r) × Ts (r)
Icp ′ (x, y, r) = Icp (x, y, r) × Tp (r) = (1-S (x, y)) × I (x, y, r) × Tp (r) ( 8)
Then, according to the following formula (9), Ics ′ (x, y, r) and primary line component Icp ′ (x, y, r) are frequency-synthesized, and a processed radiation image I (x, y) ′ is obtained. calculate.

I ′ (x, y) = Σr {Ics ′ (x, y, r) + Icp ′ (x, y, r)}
= Σr {S (x, y) × I (x, y, r) × Ts (r) + (1-S (x, y)) × I (x, y, r) × Tp (r)}
= Σr {I (x, y, r) × (S (x, y) × Ts (r) + (1-S (x, y)) × Tp (r))} (9)

  The scattered radiation suppression unit 47 estimates the body thickness distribution of the subject (subject 30) as necessary, and the scattered radiation dose is increased at a position where the body thickness of the subject is larger according to the estimated body thickness distribution of the subject. It is preferable to perform the scattered radiation suppression process so as to further reduce. Any method can be used as the body thickness distribution estimation method, and for example, the method described in JP-A-2-244881 can be employed. In addition, when the method described in Japanese Patent Application No. 2013-229941 filed by the present applicant is adopted, the body thickness distribution estimated with accuracy can be adopted for the scattered radiation suppression processing, and the body thickness of the subject is preferably A scattered radiation suppression process according to the distribution can be performed.

  Returning to FIG. 3, the continuation will be described. In the image processing unit 48, the stationary grid use image subjected to the grid stripe suppression process, the grid non-use image subjected to the scattered radiation suppression process, and neither the grid stripe suppression process nor the scattered radiation suppression process are performed. Necessary image processing such as noise removal processing for removing noise, gradation processing, and frequency processing is performed on the image using the oscillating grid to obtain a processed radiation image. The image processing unit 48 stores the processed image on which the required image processing has been performed in the storage unit 17.

  Further, the image processing unit 48 is configured to match the image quality of each processed image of the three types of images with respect to the three types of images of the swing grid use image, the still grid use image, and the grid non-use image. A setting table is prepared in which image processing parameters for required image processing of each type of image are set in advance. Based on the setting table, the image processing unit 48 performs the required image processing based on the image processing parameters for the rocking grid use image for the rocking grid use image, and the static grid use image for the static grid use image. Necessary image processing based on the image processing parameter for the used image is performed, and required image processing based on the image processing parameter for the grid non-use image is performed on the grid non-use image.

  The display control unit 49 displays the processed radiographic image on the display 50. In addition, a stationary grid use image that has been subjected to grid stripe suppression processing, a grid non-use image that has been subjected to scattered radiation suppression processing, and a oscillating grid that has not been subjected to either grid stripe suppression processing or scattered radiation suppression processing The image is subjected to image processing and displayed on the display 50. In the following description, a radiographic image that has undergone only image processing is a radiographic image G0, a radiographic image that has undergone grid stripe suppression processing and image processing is a radiographic image G1, and a radiographic image that has undergone scattered radiation suppression processing and image processing. Is a radiation image G2.

  Next, processing performed in the first embodiment will be described. FIG. 9 is a flowchart showing processing performed in the first embodiment. When the image acquisition unit 41 acquires the radiation image corresponding to the acquired dose data (step ST1) and the dose data acquisition unit 42 acquires the dose data (step ST2), the determination unit 43 determines the dose data based on the dose data. The presence or absence of the first feature is determined, and it is determined that the radiation image corresponding to the dose data having the first feature corresponds to the rocking grid use image (Yes in step ST3). When it is determined that the radiation image corresponds to the rocking grid use image, the determination unit 43 sets the image processing parameters for the rocking grid use image for the rocking grid use image and performs the required image processing. To generate a processed radiation image G0 (step ST7). Then, the display control unit 49 displays the radiation image G0 on the display 50 (step ST8).

  Further, when it is determined by the determination unit 43 that the dose data does not have the first feature, that is, when it is determined that the radiation image does not correspond to the rocking grid use image (No in step ST3), When the grid stripe detection unit 45 detects the presence or absence of grid stripes in the radiographic image and the grid stripe detection unit 45 detects the grid stripes, the determination unit 43 uses the radiographic image from which the grid stripes are detected as a stationary grid use image. It discriminate | determines (step ST4, Yes). And the grid stripe suppression part 46 performs a grid stripe suppression process with respect to a still grid use image (step ST6), and the image for a still grid use image is used for the still grid use image which the image processing part 48 performed the grid stripe suppression process. A processing parameter is set and necessary image processing is performed to generate a processed radiation image G1 (step ST7). Then, the display control unit 49 displays the radiation image G1 on the display 50 (step ST8).

  When the grid stripe detection unit 45 detects the presence or absence of grid stripes in the radiographic image and no grid stripes are detected by the grid stripe detection unit 45, the determination unit 43 grids the radiographic image in which no grid stripes are detected. It is determined as an unused image (step ST4: No). Then, the scattered radiation suppression unit 47 performs the scattered radiation suppression process on the grid non-use image (step ST5), and the image processing unit 48 performs the scattered radiation suppression process on the grid non-use image. A processing parameter is set and necessary image processing is performed to generate a processed radiation image G2 (step ST7). Then, the display control unit 49 displays the radiation image G2 on the display 50 (step ST8).

  The image analysis apparatus ends the process in response to a user instruction to end the display of the processed image. The processed radiographic image is stored in the storage unit 44 or transmitted to a server connected to the console 16 via a network and stored in the storage unit 17.

  According to the present embodiment (first embodiment), dose data that represents in a time series the radiation dose irradiated to a specific position in an imaging region corresponding to a radiographic image during a specific period including the radiographic imaging period. The acquired dose data is the dose of a plurality of radiation absorbers and a radiation transmission body located between adjacent radiation absorbers passed between a specific position and the radiation source used for radiography. It is determined whether or not the first characteristic representing the fluctuation is present, and the radiation image determined that the dose data has the first characteristic is swung by a rocking imaging grid for removing scattered radiation. It is determined that the image is a captured image using a rocking grid. For this reason, it is possible to suitably determine whether or not a radiographic image has been taken by swinging the grid by utilizing dose data. Further, the determined information can be suitably applied to, for example, a technique for performing different image processing depending on whether or not a bucky grid is used.

  In the present embodiment, the radiographic image corresponding to the dose data that is determined not to have the first feature is captured by the determination unit 43 while the stationary imaging grid for removing the scattered radiation is stopped. Since it can be determined that the image is a static grid use image and a grid non-use image taken without using a grid for removing scattered radiation, it is possible to preferably determine whether or not a rocking grid is used.

  Further, in the present embodiment, the determination unit 43 determines whether or not the radiation image has the second feature that the image includes a still shooting grid image, and the radiation image determined to have the second feature. Is determined to be a still grid use image, a radiation image that corresponds to the dose data determined not to have the first feature and is determined not to have the second feature is a grid-free image. Therefore, it is possible to suitably discriminate between the rocking grid use image, the stationary grid use image, and the grid non-use image.

  Furthermore, the present embodiment includes a grid stripe suppression unit 46 that suppresses frequency components corresponding to an image (grid stripe) representing a still shooting grid included in the still grid use image from the still grid use image. Therefore, it is possible to prevent the grid stripe suppression process from being erroneously performed on the grid non-use image and the swing grid use image, which are images having no grid stripe, according to the determination result of the grid type. As a result, an appropriate processed image can be generated and displayed.

  Also, in the present embodiment, a scattered radiation image indicating scattered radiation components at each position of the grid unused image is generated from the grid unused image, and the scattered radiation component is subtracted from the grid unused image to suppress the scattered radiation component. By including the scattered radiation suppressing unit 47 that performs processing, it is possible to prevent the scattered radiation suppressing process from being erroneously performed on the still grid use image and the swing grid use image according to the determination result of the grid type. . As a result, an appropriate processed image can be generated and displayed.

  In the present embodiment, the determination unit 43 adds determination information indicating whether or not the image is determined to be a rocking grid use image to the radiographic image as supplementary information of the radiographic image, and supplementary information of the radiographic image in subsequent processing. Referring to FIG. 4, the necessary processing and the unnecessary processing are determined for the image using the oscillating grid. For this reason, since it is possible to easily determine whether or not the image is a rocking grid non-use image by referring to the incidental information of the radiographic image, the type and presence of processing differ depending on whether or not the image is a rocking grid use image. It can provide useful information for requests that you want.

  In addition, the image processing unit 48 uses the appropriate image processing parameters according to the type of each image for the three types of images of the swing grid use image, the still grid use image, and the grid non-use image. By performing the required image processing according to the type, it is possible to provide a processed image suitable for comparative observation of different types of processed images by matching the image quality of the processed images of each image it can. Such image processing is suitable for the case of comparative observation of different types of processed images, such as when performing comparative observation over time using past radiation images in order to diagnose disease healing or progression. It is applicable to. In addition, the image processing unit 48 uses the appropriate image processing parameters according to the type of each image for the three types of images of the swing grid use image, the still grid use image, and the grid non-use image. By performing the required image processing according to the type, it is possible to reduce the burden of the operator's operation input and to perform image processing on each image accurately and efficiently.

  Note that, as in the first embodiment, when the determination unit 43 is configured to be able to determine the still grid use image and the swing grid use image, the process of determining the still grid use image and the swing grid use image As for the process of discriminating between the two, either may be performed first or may be performed simultaneously. As the second embodiment, an example will be described in which the order of the process of determining the still grid use image by the determination unit 43 and the process of determining the swing grid use image in the first embodiment are reversed. FIG. 9 is a flowchart showing processing performed in the second embodiment. The second embodiment is different only in that the order of processing is changed in the image analysis apparatus, and since each component and its function are the same as those in the first embodiment, description of common parts is omitted. . A processing flow of the image analysis apparatus according to the second embodiment will be described with reference to FIG.

  First, when the image acquisition unit 41 acquires a radiation image corresponding to the acquired dose data (step ST11) and the dose data acquisition unit 42 acquires the dose data (step ST12), the grid fringe detection unit 45 detects the radiation image. When the presence or absence of the grid stripe is detected and the grid stripe is detected by the grid stripe detection unit 45, the determination unit 43 determines that the radiographic image from which the grid stripe is detected corresponds to the still grid use image (step ST13: Yes). ). And the grid stripe suppression part 46 performs a grid stripe suppression process with respect to a still grid use image (step ST15), and the image process part 48 performs a required image process to the static grid use image in which the grid stripe suppression process was performed. The processed radiation image G1 is generated (step ST17). Then, the display control unit 49 displays the radiation image G1 on the display 50 (step ST18).

  When the grid stripe is not detected from the radiation image by the grid stripe detection unit 45, the determination unit 43 determines that the radiation image does not correspond to the stationary grid use image (No in step ST13). In this case, the determination unit 43 determines the presence / absence of the first feature of the dose data based on the dose data, and determines the radiation image corresponding to the dose data having the first feature as the image using the swing grid. (Step ST14, Yes). Thereafter, the image processing unit 48 performs necessary image processing on the swing grid use image to generate a processed radiation image G0 (step ST17). Then, the display control unit 49 displays the radiation image G0 on the display 50 (step ST18).

  Further, the determination unit 43 determines the presence or absence of the first feature of the dose data based on the dose data, and if the radiation image corresponding to the dose data not having the first feature does not correspond to the rocking grid use image. It discriminate | determines (step ST14, No). In this case, since the radiographic image is an image that does not correspond to the still grid use image or the swing grid use image, the determination unit 43 determines the radiographic image as a grid nonuse image. The scattered radiation suppression unit 47 performs the scattered radiation suppression process on the grid non-use image (step ST16), and the image processing unit 48 performs the required image processing on the grid non-use image on which the scattered radiation suppression process has been performed. The processed radiation image G2 is generated (step ST17). Then, the display control unit 49 displays the radiation image G2 on the display 50 (step ST18).

  As shown in the second embodiment, even if the order of the rocking grid use image discrimination process and the stationary grid use image discrimination process is changed, the same effect as in the first embodiment can be obtained. It is preferable to determine the order of the swing grid use image discrimination process and the stationary grid use image discrimination process according to the circumstances required for each system.

  In addition, the determination unit 43 may use a combination of processing for determining the rocking grid use image based on whether the dose data has the first feature and processing for determining the rocking grid use image by another method. Good. As a third embodiment, which is a modification of the first embodiment, the determination unit 43 indicates that the radiographic image has been captured by oscillating the rocking imaging grid based on the imaging instruction information indicating the radiographic image capturing instruction. The rocking grid use image is determined based on the rocking grid information of the shooting instruction information when it is determined that the rocking grid information is included in the shooting instruction information. An example will be described in which it is determined whether or not the dose data has the first feature when it is determined that the rocking grid information is not included in the imaging instruction information.

  FIG. 11 is a flowchart showing processing performed in the third embodiment. In the third embodiment, the rocking grid is determined depending on whether or not the determination unit 43 includes rocking grid information indicating whether or not the imaging instruction information indicating the radiographic image capturing instruction is captured by rocking the grid. Unlike the first embodiment, only the function of discriminating the image used is different from the first embodiment, and the other functions and other components of the discrimination unit 43 and their functions are the same as those in the first embodiment. Description of common parts is omitted. A processing flow of the image analysis apparatus according to the third embodiment will be described with reference to FIG.

  The “imaging instruction information” is information transmitted from the doctors to the person in charge of imaging for an imaging instruction, and is information including information for specifying the imaging target and the image inspection performed on the imaging target. For this reason, there is a possibility that the shooting instruction information includes an instruction for shooting by swinging the grid. When the shooting instruction information includes information instructing rocking of the grid, the determination unit 43 can acquire the rocking grid information by referring to the shooting instruction information. For example, the imaging instruction information includes basic information related to an imaging target such as a patient name, sex, and age, a radiographic imaging instruction, a range / direction to be imaged, and imaging conditions.

  As shown in FIG. 11, the determination unit 43 first swings the oscillating imaging grid to the imaging instruction information representing the radiographic image capturing instruction by acquiring and referring to the imaging instruction information corresponding to the radiographic image. Then, it is determined whether or not rocking grid information indicating whether or not the image has been shot is included (step ST21). When the imaging instruction information corresponding to the radiographic image includes the rocking grid information, the determination unit 43 determines that the radiographic image corresponds to the rocking grid use image (Yes in step ST21). Then, the image processing unit 48 sets the image processing parameters for the oscillating grid use image for the oscillating grid use image and performs the required image processing to generate a processed radiation image G0 (step ST28). . Then, the display control unit 49 displays the radiation image G0 on the display 50 (step ST29).

  On the other hand, when the rocking grid information is not included in the shooting instruction information (No in step ST21), the determination unit 43 performs the same processing as ST1 to ST8 in the first embodiment. That is, when the radiation image corresponding to the acquired dose data is acquired by the image acquisition unit 41 (step ST22) and the dose data acquisition unit 42 acquires the dose data (step ST23), the determination unit 43 is based on the dose data. The presence / absence of the first feature of the dose data is determined, and it is determined that the radiation image corresponding to the dose data having the first feature corresponds to the rocking grid use image (Yes in step ST24). When it is determined that the radiographic image corresponds to the rocking grid use image, the image processing unit 48 sets an image processing parameter for the rocking grid use image with respect to the rocking grid use image to obtain a required image. Processing is performed to generate a processed radiation image G0 (ST28). Then, the display control unit 49 displays the radiation image G0 on the display 50 (step ST29).

  Further, when it is determined by the determination unit 43 that the dose data does not have the first feature, that is, when it is determined that the radiation image does not correspond to the rocking grid use image (No in Step ST24), When the grid stripe detection unit 45 detects the presence or absence of grid stripes in the radiographic image and the grid stripe detection unit 45 detects the grid stripes, the determination unit 43 uses the radiographic image in which the grid stripes are detected as a stationary grid use image. Discriminate (step ST25, Yes). Then, the grid stripe suppression unit 46 performs grid stripe suppression processing on the still grid use image (step ST27), and the image processing unit 48 adds the still grid use image to the still grid use image that has been subjected to grid stripe suppression processing. A processing parameter is set and necessary image processing is performed to generate a processed radiation image G1 (step ST28). Then, the display control unit 49 displays the radiation image G1 on the display 50 (step ST29).

  When the grid stripe detection unit 45 detects the presence or absence of grid stripes in the radiographic image and no grid stripes are detected by the grid stripe detection unit 45, the determination unit 43 grids the radiographic image in which no grid stripes are detected. It is determined as an unused image (step ST25, No). Then, the scattered radiation suppression unit 47 performs the scattered radiation suppression process on the grid non-use image (step ST26), and the image processing unit 48 performs the scattered radiation suppression process on the grid non-use image. A processing parameter is set and necessary image processing is performed to generate a processed radiation image G2 (step ST28). Then, the display control unit 49 displays the radiation image G2 on the display 50 (step ST29).

  According to the third embodiment, it is used that imaging instruction information is associated with each radiographic image, and the imaging instruction information is information including information for specifying an imaging test performed on the imaging target and the imaging target. Thus, only when the oscillating grid information cannot be obtained by the imaging instruction information, the process of discriminating the oscillating grid use image is performed, so that the radiation image is oscillated grid while reducing calculation load and speeding up. It is possible to suitably determine whether the image is a use image.

  Further, the rocking grid information, which is information indicating whether or not the radiation image obtained by the determination unit 43 according to the embodiment of the present invention corresponds to the rocking grid use image, is an arbitrary one that requires rocking grid information. It can be used for any processing of the device.

  In the embodiment of the present invention, the grid stripe detection unit 45, the grid stripe suppression unit 46, the scattered radiation suppression unit 47, the image processing unit 48, and the display control unit 49 are not essential components and may be omitted. Further, the process of acquiring dose data (for example, ST1 in FIG. 9) and the process of acquiring a radiation image corresponding to the dose data (for example, ST2 of FIG. 9) may be performed first or simultaneously. Also good.

  In the present embodiment, the console 16 and the radiation image processing device 14 are provided as separate devices. However, the present invention is not limited to this, and the console 16 and the radiation image processing device 14 are integrated into one device. 16 and the components and functions of the radiation image processing apparatus 14 may be configured by a single console.

  In each of the above embodiments, the scattered radiation suppression process is performed using the radiation image acquired in the radiation image capturing system 10 that captures the radiation image of the subject using the radiation detector 26. Obtained by accumulating and recording radiographic image information of a subject on a stimulable phosphor sheet as a radiation detector shown in Japanese Patent Publication No. 266529, Japanese Patent Laid-Open No. 9-24039, etc. Of course, the present invention can be applied even when a radiation image is used.

  Moreover, the process which removes the striped pattern resulting from a grid can be performed with the various method which can remove the striped pattern resulting from a grid. For example, the method described in JP2012-203504A can be referred to.

  Each above-mentioned embodiment is an illustration to the last, and all the above-mentioned explanations should not be used in order to interpret the technical scope of the present invention limitedly. The aspect of the present invention is not limited to the above-described individual examples (first to third embodiments, other modifications and application examples), and any combination of elements of the individual examples is not limited to the present invention. In addition, various modifications that can be conceived by those skilled in the art are also included. That is, various additions, modifications, and partial deletions can be made without departing from the concept and spirit of the present invention derived from the contents defined in the claims and equivalents thereof.

  In addition, the system configuration, the hardware configuration, the processing flow, the module configuration, the user interface, the specific processing content, etc. in the above embodiment have been variously modified without departing from the spirit of the present invention. It is included in the technical scope of the present invention. For example, some or all of the components of the image analysis apparatus may be configured by a single workstation, or may be configured by one or more workstations, servers, and storage devices connected via a network. Good.

DESCRIPTION OF SYMBOLS 10 Radiographic imaging system 12 Radiation generation apparatus 14 Radiation image processing apparatus 16 Console 17 Memory | storage part 18 Radiographic image interpretation apparatus 20 Electronic cassette 22A Radiation source 26 Radiation detector 40 Control part 41 Image acquisition part (radiation image acquisition part)
42 Dose Data Acquisition Unit 43 Discrimination Unit 44 Storage Unit 45 Grid Stripe Detection Unit 46 Grid Stripe Suppression Unit 47 Scattered Ray Suppression Unit 48 Image Processing Unit 49 Display Control Unit

Claims (9)

A radiological image acquisition unit for acquiring a radiographic image obtained by radiography;
A dose data acquisition unit for acquiring dose data representing, in a time series, a radiation dose irradiated to a specific position in an imaging region corresponding to the radiographic image in a specific period including an imaging period of the radiographic image;
The dose of the dose data obtained when a plurality of radiation absorbers and a radiation transmission body located between the adjacent radiation absorbers pass between the specific position and the radiation source used for the radiography. It is determined whether or not it has a first feature that represents a fluctuation of the image, and the radiographic image corresponding to the dose data determined not to have the first feature is subjected to still photography for removing scattered radiation A discriminating unit for discriminating whether the image is a static grid use image that is captured with the grid for static use or a grid non-use image that is captured without using a grid for removing scattered radiation;
An image analysis apparatus comprising:   The said discrimination | determination part discriminate | determines whether the said dose data have the said 1st characteristic by making into the said 1st characteristic the characteristic that the said dose data has the adjacent sine wave shape of fixed amplitude. Image analysis device.   The determination unit is characterized in that the dose data alternately has a positive maximum value caused by the passage of the radiation transmitting body and a minimum value of zero or more caused by the passage of the radiation absorber at a certain interval. The image analysis apparatus according to claim 1, wherein the image analysis apparatus determines whether the dose data has the first feature as the first feature.   The discriminating unit discriminates whether or not the radiographic image has a second feature that includes an image of the still photographing grid, and the radiographic image discriminated to have the second feature is determined to be the static grid. The radiographic image determined to be a use image, corresponding to the dose data determined not to have the first feature, and not determined to have the second feature is not used in the grid The image analysis apparatus according to claim 1, wherein the image analysis apparatus determines that the image is an image.   The grid stripe suppression part which suppresses the frequency component corresponding to the image showing the said grid for still photography contained in this static grid use image from the said static grid use image is further provided. Image analysis device.   Scattering that performs scattered radiation component suppression processing by generating a scattered radiation image that indicates scattered radiation components at each position of the grid-free image from the grid-free image and subtracting the scattered radiation image from the grid-free image The image analysis apparatus according to claim 1, further comprising a line suppression unit.   The image analysis apparatus according to claim 1, wherein the determination unit adds determination information indicating whether the image is determined to be the still grid use image to the radiation image as incidental information. An image analysis method to be executed by an image analysis apparatus,
A radiological image acquisition step of acquiring a radiographic image obtained by radiography;
A dose data acquisition step for acquiring dose data representing, in a time series, a radiation dose irradiated to a specific position in an imaging region corresponding to the radiographic image in a specific period including an imaging period of the radiographic image;
The dose of the dose data obtained when a plurality of radiation absorbers and a radiation transmission body located between the adjacent radiation absorbers pass between the specific position and the radiation source used for the radiography. It is determined whether or not it has a first feature that represents a fluctuation of the image, and the radiographic image corresponding to the dose data determined not to have the first feature is subjected to still photography for removing scattered radiation A discriminating step for discriminating that the image is a static grid use image captured with the grid for stationary and a grid non-use image captured without using the grid for removing scattered radiation;
An image analysis method characterized by comprising: On the computer,
A radiological image acquisition step of acquiring a radiographic image obtained by radiography;
A dose data acquisition step for acquiring dose data representing, in a time series, a radiation dose irradiated to a specific position in an imaging region corresponding to the radiographic image in a specific period including an imaging period of the radiographic image;
The dose of the dose data obtained when a plurality of radiation absorbers and a radiation transmission body located between the adjacent radiation absorbers pass between the specific position and the radiation source used for the radiography. It is determined whether or not it has a first feature that represents a fluctuation of the image, and the radiographic image corresponding to the dose data determined not to have the first feature is subjected to still photography for removing scattered radiation A discriminating step for discriminating that the image is a static grid use image captured with the grid for stationary and a grid non-use image captured without using the grid for removing scattered radiation;
An image analysis program characterized by causing