JP6790544B2 - Tomosynthesis photographed image selection device and tomosynthesis photographed image generation system - Google Patents

Description

The present invention relates to a tomosynthesis photographed image selection device and a tomosynthesis photographed image generation system.

Conventionally, in the medical field, the subject is radiographed while changing the positional relationship between the radiation source and the radiation detector, as in tomosynthesis imaging and CT (Computed Tomography) imaging, and the obtained projected image is reconstructed. A technique for generating a reconstructed image (tomographic image) of a subject is known.

In tomosynthesis imaging, a considerable number of reconstructed images are generated. This includes images in which the area of interest (the area including the suspected lesion and its surroundings) is blurred for the doctor making the diagnosis, and images in which the area of interest is not shown.
If a large number of unnecessary images that are almost useless for a doctor's diagnosis are sent to an image interpreter as an image for interpretation, many images including unnecessary images are included every time the doctor interprets the image. You have to look at the image and it is inefficient.

In this regard, for example, Patent Document 1 includes a determination means for determining an invalid image region based on the position information of the radiation source and the radiation detector when obtaining a captured image, and a tomosynthesis image obtained according to the determination result. Is disclosed as a device for displaying the above on the display unit.

JP 2015-000322

However, in the technique described in Patent Document 1, those determined to be invalid image regions from the position information of the radiation source and the radiation detector at the time of obtaining a captured image can be excluded from the display image. Strictly defining the range of reconstruction that is effective for interpretation poses many technical problems, and images that are inappropriate for diagnosis remain as display targets.
For this reason, an image that is not useful for interpretation is also displayed, and there is a problem that it takes a long time to interpret an image because a useless image is checked.

The present invention has been made in view of the above points, and by accurately selecting an image that is not useful for interpretation and excluding it from the display target, the interpretation time can be shortened and the interpretation can be efficiently performed with high accuracy. It is an object of the present invention to provide a tomosynthesis photographed image selection device and a tomosynthesis photographed image generation system capable of performing the same.

In order to solve the above problems, the tomosynthesis image selection apparatus of the present invention is used.
Positions of a radiation source that irradiates a subject with radiation and a radiation detector in which radiation detection elements that detect radiation and generate an electrical signal are arranged in a two-dimensional manner and acquire a projected image according to the irradiated radiation. A plurality of reconstructions obtained by acquiring the projected image of the subject arranged between the radiation source and the radiation detector a predetermined number of times and reconstructing the plurality of projected images while changing the relationship. The image is characterized by comprising a deletion target image selection means for selecting an image in which a region of interest in the image is blurred or deviated as a deletion target image.

In addition, the tomosynthesis photographed image generation system, which is another aspect of the present invention,
It is equipped with a radiation source that irradiates a subject with radiation, and a radiation detector in which radiation detection elements that detect radiation and generate an electric signal are arranged in a two-dimensional manner and acquire a projected image according to the irradiated radiation. An imaging means for acquiring the projected image of a subject arranged between the radiation source and the radiation detector a predetermined number of times while changing the positional relationship between the radiation source and the radiation detector.
A reconstructed image generating means that reconstructs a plurality of projected images acquired by the photographing means to generate a reconstructed image of the subject, and
Among the plurality of reconstructed images generated by the reconstructed image generating means, a deletion target image selection means for selecting an image in which a region of interest in the image is blurred or deviated as a deletion target image, and
A display means for displaying the reconstructed image excluding the image to be deleted and the image selected by the deletion target image selection means as a display image, and
It is characterized by having.

According to the tomosynthesis photographed image selection device and the tomosynthesis photographed image generation system as in the present invention, images that are not useful for interpretation are accurately selected and excluded from the display target to shorten the interpretation time and efficiently increase the efficiency. It enables accurate interpretation.

It is a figure which shows the whole structure of the image generation system which concerns on this embodiment. It is a block diagram which shows the functional structure of the console of FIG. It is a flowchart which shows the image generation processing executed by the control part of FIG. It is a flowchart which shows the image selection process in the 1st Embodiment executed by the control part of FIG. It is a figure which shows an example of the sharp reconstruction image of the knee part of a leg. It is a figure which shows an example of the non-sharp reconstruction image of the knee part of a leg. It is a figure which shows an example of the FFT image of the region of interest of the reconstructed image shown in FIG. 5 and FIG. It is a figure which shows an example of the power spectrum of the FFT image shown in FIG. 7. It is a flowchart which shows the image selection process in 2nd Embodiment. It is a graph which shows an example of the inspection time of a reconstructed image. It is a graph which shows an example of the inspection time of a reconstructed image.

[First Embodiment]
A first embodiment of the tomosynthesis photographed image selection device and the tomosynthesis photographed image generation system according to the present invention will be described with reference to FIGS. 1 to 8. The present invention is not limited to the illustrated examples.

<Configuration of image generation system 100>
First, a schematic configuration of an embodiment of a tomosynthesis photographed image generation system (hereinafter, simply referred to as an “image generation system”) according to the present invention will be described.
FIG. 1 shows a schematic configuration of the image generation system 100 according to the present embodiment.
The image generation system 100 generates a reconstructed image (tomographic image) of the subject H using a plurality of projected images obtained by taking a tomosynthesis image of the subject H (a part of the human body), and also generates a reconstructed image (tomographic image). Is a system that displays on the display unit.

As shown in FIG. 1, the image generation system 100 mainly includes a radiography apparatus 1, a console 90, and the like.
In the following description, the longitudinal direction of the subject base 54 (the body axis direction of the subject H arranged on the subject base 54) is orthogonal to the y-axis direction, and the photographing surface (the surface irradiated with radiation) is orthogonal to the y-axis direction. The direction will be described as the x-axis direction, and the irradiation direction (thickness (height) direction of the subject H) will be described as the z-axis direction.

The image generation system 100 is provided inside and outside the photographing room 101a and the front room (also referred to as an operation room or the like) 101b. In the photographing room 101a, a photographing table 50 of the radiation photographing apparatus 1, a radiation source 61, and the like are provided. Further, in the photographing room 101a, an access point AP or the like for relaying wireless communication between the radiation detector F and the console 90 described later is also provided.

Further, the front chamber 101b is provided with an operation console 62 of the radiation irradiation device 60, an exposure switch 63, and the like. Further, although FIG. 1 shows a case where the control BOX 80, the console 90, etc. are provided outside the anterior chamber 101b, it is also possible to provide them in the anterior chamber 101b or the like.

As shown in FIG. 1, the radiation imaging device 1 as an imaging means includes a radiation detector F, an imaging table 50 for holding the radiation detector F and the subject H, and a radiation irradiation device 60. There is. Note that FIG. 1 shows, as an example, a side view of a radiation photographing apparatus 1 for photographing the subject H in the recumbent position.

The radiation detector F is composed of a semiconductor image sensor such as an FPD (Flat Panel Detector). The FPD has, for example, a glass substrate or the like, and detects and detects radiation (X-rays) irradiated from a radiation source 61 and transmitted at least through the subject H at a predetermined position on the substrate according to its intensity. A plurality of detection elements (pixels) that convert radiation into an electric signal and store it are arranged in a matrix. Each pixel is configured to include, for example, a switching unit such as a TFT (Thin Film Transistor), and the reading of the electric signal stored in each pixel is switched by the switching unit and stored in the radiation detector F. A projected image of the subject H is acquired by reading the electric signal. The FPD has an indirect conversion type in which radiation is converted into an electric signal by a photoelectric conversion element via a scintillator and a direct conversion type in which radiation is directly converted into an electric signal, and either of them may be used.
The radiation detector F has a function of communicating with the console 90 via the network N1 and the control BOX 80, and a wireless communication function for communicating with the console 90 via the access point AP.

The photographing table 50 includes a detector loading unit 51, a loading unit support unit 52, a subject table 54, and the like.
The detector loading unit 51 holds the radiation detector F.
The loading portion support portion 52 is provided on the side of the subject base 54 opposite to the surface on which the subject H is placed, and supports the detector loading portion 51.

The irradiation device 60 includes a radiation source 61 that irradiates the radiation detector F through the subject H, and an operation console that allows a photographer such as a radiation engineer to set imaging conditions such as tube current, tube voltage, and irradiation time. 62, the exposure switch 63 operated by the photographer to instruct the irradiation of radiation from the radiation source 61, and the radiation source 61 moved along the body axis direction of the subject H on the subject table 54 (in the y-axis direction). It is also provided with a radiation source moving mechanism 64 or the like that tilts the irradiation angle of the radiation source 61 according to the position so that the radiation emitted from the radiation source 61 at the moved position is irradiated to the radiation detector F. .. When the imaging conditions are set from the console 90 via the control BOX 80 or by the console 62 and the exposure switch 63 is pressed, the radiation irradiation device 60 transmits a pressing signal of the exposure switch 63 to the console 90. Based on the control signal from the console 90, the radiation source 61 is moved by the radiation source moving mechanism 64 under the set imaging conditions, and the radiation source 61 is irradiated with radiation.
Further, in the irradiation direction of the radiation source 61, a collimator 75 that limits the irradiation region of the radiation emitted from the radiation source 61 is provided.

In the present embodiment, as the radiation source 61 of the radiation irradiation device 60, a radiation source that irradiates the subject H and the radiation detector F in a conical shape, that is, a radiation source that irradiates a so-called cone beam is used. ..

The radiation source moving mechanism 64 moves the radiation source 61 along the subject table 54 (that is, in the y-axis direction) in response to a control signal transmitted from the console 90 via the control BOX 80 described later, thereby causing radiation. The relative positional relationship between the source 61 and the radiation detector F is changed.

The radiation imaging device 1 having the above configuration performs tomosynthesis imaging a predetermined number of times (multiple times) while the radiation source 61 moves from a predetermined imaging start position to an imaging start position in the opposite direction, and a radiation detector is used for each imaging. It is configured to acquire a projected image with F. At this time, the optical axis of the radiation source 61 is configured to irradiate the center of the radiation detector F.

At that time, for example, radiation is irradiated from the radiation source 61 a predetermined number of times (pulse irradiation), and a projected image is acquired by the radiation detector F each time the radiation is irradiated. Alternatively, the radiation from the radiation source 61 may be continuously irradiated without interruption, and the radiation detector F may be configured to acquire the projected image a predetermined number of times during that period.

The radiation detector F may be configured to transmit the acquired projection image to the console 90 as an image processing device via the control BOX 80 each time the projection image is acquired, or each acquired projection. It is also possible to temporarily store the images in a storage unit (not shown), and to transmit the projected images together to the console 90 when the acquisition process of the projected images a predetermined number of times is completed.

The control BOX (also referred to as a repeater or the like) 80 is connected to each part of the radiography apparatus 1, a radiation detector F loaded in the detector loading part 51, a console 90, or the like via a network N1. The control BOX 80 is shown in which a signal for LAN (Local Area Network) communication transmitted from the console 90 or the like to the radiation irradiation device 60 is converted into a signal or the like for the radiation irradiation device 60, and vice versa. Does not have a built-in converter.

As shown in FIG. 2, the console 90 is a computer device including a control unit 91, an operation unit 92, a display unit 93, a communication unit 94, and a storage unit 95, and each unit is connected by a bus 96. is there.

The control unit 91 is composed of a CPU, RAM, and the like. The CPU of the control unit 91 reads various programs such as system programs and processing programs stored in the storage unit 95 and expands them into RAM, and according to the expanded programs, image generation processing and tomosynthesis photographed image selection processing (hereinafter referred to as). , Simply "image selection process") and other various processes are executed. The control unit 91 functions as a reconstruction image generation means, a deletion target image selection means, a display control means, and the like in cooperation with a program stored in the storage unit 95. Further, the control unit 91 functions as a designation means, a switching means, and the like in cooperation with the operation unit 92.

The operation unit 92 is configured to include a keyboard equipped with character input keys, number input keys, various function keys, and a pointing device such as a mouse, and a key press signal operated by the keyboard and an operation signal by the mouse. Is output to the control unit 91 as an input signal.

The display unit 93 is configured to include, for example, a monitor such as an LCD (Liquid Crystal Display), and displays various screens in accordance with instructions of display signals input from the control unit 91.
In the present embodiment, as will be described later, the display unit 93 serves as a display means for displaying a reconstructed image excluding the image to be deleted and the image selected by the control unit 91, which is the image selection means for deletion, as a display image. Function.

The communication unit 94 is a communication means that is composed of a LAN card or the like and transmits / receives data to / from an external device connected to networks N1 and N2 via a switching hub. The communication unit 94 functions as a first transmission means, a second transmission means, or a third transmission means.

The storage unit 95 is composed of, for example, an HDD (Hard Disk Drive), a semiconductor non-volatile memory, or the like. As described above, the storage unit 95 stores the system program and various processing programs.

Further, in the storage unit 95, a projection image storage unit 951 that stores the projection image received from the radiation detector F, a reconstruction image storage unit 952 that stores the generated reconstructed image, and an image to be deleted among the reconstructed images are stored. A display image storage unit 953 or the like for storing the removed display image is provided.
Further, the storage unit 95 is associated with at least one of the imaging site, imaging direction, patient size (for example, adult large, medium, small, child large, medium, small), etc., in the reconstructed image. An index for identifying an area of interest (a part of the reconstructed image to be diagnosed by a doctor, for example, a lesion site and its surroundings) is stored.

The console 90 transmits an awakening signal to the radiation detector F via, for example, the access point AP or the control BOX 80 by the communication unit 94 to shift the radiation detector F from the sleep state to the wake up state. Then, the radiation detector F is controlled, the tube current or the like set by the photographer such as a radiologist by the operation unit 92 is transmitted to the radiation irradiation device 60 via the control BOX 80 and set, or the radiation detector F is set via the control BOX 80. The radiation source moving mechanism 64 can be controlled.

In the present embodiment, the console 90 also functions as an image processing device, and when the projected image acquired by the radiation detector F is transmitted from the radiographing device 1, the received projection images are displayed. Based on this, a reconstructed image of the subject H is generated, and each of the plurality of projected images is back-projected to generate a plurality of back-projected images.
Further, in the present embodiment, the console 90 functions as a tomosynthesis captured image selection device including a deletion target image selection means for selecting an image that does not satisfy a predetermined condition suitable for interpretation as a deletion target image for the reconstructed image of the subject H. To do.
It is also possible to configure the image processing device and the tomosynthesis captured image selection device as a device separate from the console 90.

Further, as shown in FIG. 1, an access point AP is connected to the console 90 via the network N2. Further, the console 90 is a separate system via the network N2, such as HIS (Hospital Information System), RIS (Radiology Information System), and PACS (Picture Archiving and Communication System). Diagnosis support system) It is connected to 70 and the like. The console 90 is configured to perform various processes such as acquiring shooting order information from HIS, RIS, or the like, and transmitting the generated reconstructed image and back projection image to the PACS 70 in association with each other. ..

It is not necessary to separately configure the network connecting each device or the like with a plurality of networks N1 and N2 as in the present embodiment, and it is also possible to connect each device to one network to configure the image generation system 100. It is possible. Further, when a plurality of networks are used as the network connecting each device as in the present embodiment, which device is connected to which network can be appropriately changed.

<Operation of image generation system 100>
Next, the operation of the image generation system 100 in the present embodiment, particularly the operation of the console 90 as a tomosynthesis captured image selection device will be described.
First, the image generation process executed by the control unit 91 of the console 90 will be described. The image generation process is executed in collaboration with the program stored in the control unit 91 and the storage unit 95.

FIG. 3 is a flowchart showing an outline of the image generation process by the image generation system 100.
As shown in FIG. 3, first, the control unit 91 performs tomosynthesis imaging and acquires a plurality of (n) projected images of the subject H (step S1).
Specifically, when the imaging order information is selected by the operation unit 92 and the exposure switch 63 is pressed, the control unit 91 controls each device of the radiation imaging device 1 via the control BOX 80 to generate a radiation source. By moving the 61 along the body axis direction of the subject H, a predetermined number of times of imaging are performed while changing the positional relationship between the radiation source 61 and the radiation detector F. A series of projected images obtained by photographing is transmitted to the console 90 by the radiation detector F. In the console 90, for each of the series of projected images received by the communication unit 94, an examination ID for identifying the examination, an image ID for identifying the image, patient information, and imaging conditions (imaging site) of the projected image are used. , Imaging direction, tube voltage, position of radiation source 61 and radiation detector F when each projected image is captured, etc.) are attached and stored in the projected image storage unit 951.

Next, the control unit 91 for generating the reconstructed image generates a reconstructed image having a plurality of slice heights at preset slice intervals using the acquired series of projected images (step S2). For example, using known methods such as the FBP (Filtered Back Projection) method, the successive approximation image reconstruction method, the Feldkamp method, and the shift addition method, a reconstruction image having a plurality of slice heights is generated from a series of projected images. .. Each of the generated reconstructed images includes an image ID for identifying the image, an examination ID, patient information, imaging conditions (imaging site, imaging direction, tube voltage, etc.), reconstruction conditions (for example, slice height, etc.). (Slice interval, etc.) is attached.

5 and 6 show an example of the reconstructed image generated by the control unit 91 for generating the reconstructed image.
5 and 6 are a plurality of projected images of the knee joint of a human leg and its surroundings (for example, three projected images obtained by taking three images while changing the position of the radiation source 61). Shows the reconstructed image generated from.
The reconstructed image is generated by back-projecting all the captured projected images onto a slice-height surface (slice surface) and adding them together. Since the structure located on the slice surface (including the lesion; the same applies hereinafter) is back-projected to the same position (position of the structure) from the projected image taken at any position of the radiation source 61. In the reconstructed image, back projections from a plurality of projected images are overlapped to obtain a tomographic image in which only the cross section of the structure located on the slice plane is emphasized. On the other hand, the structure located at a height other than the slice surface is back-projected to a different position depending on the position of the radiation source 61. Therefore, in the reconstructed image, the structure located on the surface other than the slice surface is blurred.
Of the reconstructed images, the image in which the area of interest (that is, the part to be diagnosed by the doctor) is blurred or shifted (for example, FIG. 6) is not suitable for diagnosis, and when interpreting the image, It is preferable to delete such an image and display only an image useful for interpretation.

Therefore, next, the control unit 91 performs an image selection process for selecting the reconstructed image of the subject H as the image to be deleted, as an image to be deleted, an image that does not satisfy a predetermined condition suitable for interpretation (step S3). ).
FIG. 4 is a flowchart showing a specific content of the image selection process (step S3) of the present embodiment performed by the control unit 91 as the image selection means for deletion.

As shown in FIG. 4, the control unit 91 first reads out the imaging site, imaging direction, and patient size of the reconstructed image to be image selection processing with reference to the storage unit 95 (step S11), and based on these. The region of interest in the reconstructed image is specified (step S12).
For example, in FIGS. 5 and 6, the imaging site is the knee of the leg, and the region of interest (region of interest Ar1 surrounded by the alternate long and short dash line in FIGS. 5 and 6) is the joint portion of the knee and its surroundings. FIG. 5 shows an example of a sharp image, and FIG. 6 shows an example of a non-sharp image.
When the region of interest Ar1 is specified, the control unit 91 Fourier transforms the reconstructed image in this region to create an FFT (Fast Fourier Transform) image (step S13). FIG. 7 shows an example of an FFT image created for the region of interest Ar1.
Next, the control unit 91 creates a power spectrum based on the FFT image (step S14).

FIG. 8 is a diagram showing an example of a power spectrum created by the control unit 91 for the region surrounded by the alternate long and short dash line in FIG. 7 (region Ar2 in FIG. 7). In FIG. 8, the power spectrum of a sharp image suitable for diagnosis (for example, FIG. 5) is shown by a thick solid line, and the power spectrum of a non-sharp image unsuitable for diagnosis (for example, FIG. 6) is shown by a thick dashed line.
As shown in FIG. 8, when the power spectra of a sharp image suitable for diagnosis (for example, FIG. 5) and a blurred image unsuitable for diagnosis (non-sharp image) are compared, 5 to 10 cycles / 10 cycles with relatively many low frequency components. There is no big difference in the signal amount at mm, but when comparing the signal amount at 15 to 20 cycles / mm, which has a relatively large amount of high frequency components, it can be seen that the non-sharp image has a feature that the high frequency component is less than that of the sharp image. ..
Therefore, the control unit 91 adds up the signals at 5 to 10 cycles / mm and adds up the signals at 15 to 20 cycles / mm (step S16) for each reconstructed image, and sets the ratio for each frequency band. Calculate (step S17). Then, a reconstructed image having a high frequency component less than a predetermined value is selected as a deletion target image that does not satisfy a predetermined condition suitable for image interpretation (step S18).

It should be noted that the predetermined value, which is a criterion for determining whether or not the image is to be deleted, is appropriately set. The predetermined value may be set in advance according to the imaging site or the like. In this case, the predetermined value may be stored in the storage unit 95 or the like in association with the imaging portion or the like.
The method by which the control unit 91 determines whether or not the high frequency component is less than a predetermined value is not particularly limited. For example, using the ratio of the high-frequency component to the medium-frequency component as a criterion, it is determined whether or not the reconstructed image does not satisfy the predetermined conditions suitable for image interpretation, and the predetermined conditions are not satisfied. (In this embodiment, the high frequency component is less than the predetermined value), it may be selected as the image to be deleted.

In the present embodiment, the control unit 91, which is the deletion target image selection means, determines whether or not the plurality of reconstructed images satisfy the predetermined conditions suitable for image interpretation in the order of shooting time series. Then, if there is a reconstructed image that is determined not to satisfy the predetermined condition suitable for interpretation among the reconstructed images determined to satisfy the predetermined condition suitable for interpretation, this is not regarded as the image to be deleted. The image is changed to a display image (step S19).
Since the reconstructed image is a tomographic image (slice image) continuous in the thickness direction of the subject H along the time series, for example, when there are 70 reconstructed images (slice images), the 15th reconstructed image is reconstructed. After it is said that the constituent images satisfy the predetermined conditions suitable for interpretation, the 25th and 26th images are tentatively while the reconstructed images are continuous up to the 35th image satisfying the predetermined conditions suitable for interpretation. Even if only the reconstructed image does not satisfy the predetermined conditions suitable for interpretation, the 25th and 26th reconstructed images should represent one fault plane of the subject H. In this case, it is not preferable to exclude these images from the images used for interpretation. Therefore, in the present embodiment, these images are included in the display image used for interpretation.
As a result, it is possible to prevent the image constituting one tomographic surface of the subject H from being excluded from the image interpretation target.

It should be noted that the determination method for exceptionally including an image that does not satisfy the predetermined conditions suitable for image interpretation in the display image is not particularly limited.
For example, when the control unit 91, which is a means for selecting an image to be deleted, determines whether or not a predetermined condition suitable for image interpretation is satisfied for a plurality of reconstructed images in the order of shooting time, if the predetermined condition suitable for image interpretation is satisfied. When a reconstructed image determined not to satisfy a predetermined condition suitable for image interpretation appears after a predetermined number of the determined reconstructed images are consecutive, the image may be exceptionally included in the display image.
When images that satisfy certain conditions suitable for interpretation and images that do not meet the conditions appear alternately, it may be doubtful whether the images that satisfy the conditions are images that constitute one tomographic plane of subject H. is there. In this regard, when a predetermined number of reconstructed images determined to satisfy a predetermined condition suitable for interpretation are consecutive, there is a high possibility that these images constitute one tomographic plane of the subject H, and the images are continuous. Even if there is an image that does not satisfy some conditions in the middle of the image, it is not preferable to exclude it. In this regard, when a reconstructed image that does not satisfy the predetermined condition suitable for interpretation appears after a predetermined number of reconstructed images that satisfy the predetermined condition suitable for interpretation appear, the image is exceptionally included in the display image. Therefore, it is possible to more appropriately select whether or not to use the display image.

When the image selection process is completed as described above, returning to FIG. 3, the control unit 91 stores the display image excluding the image to be deleted from the reconstructed image in the display image storage unit 953 of the storage unit 95. (Step S4). Then, at the time of image inspection by a radiologist or interpretation by a doctor, this display image is displayed on the display unit 93 (step S5).
The display of the display image may be a list of a plurality of images, or may be sequentially switched and displayed. In the case of sequential display, continuous sequential display (moving image display) may be performed, or sequential switching display (manual display) may be performed according to the operation of the operation unit 92. For example, a slide bar or a playback switching button (not shown) may be displayed on the display screen of the display unit 93 so that the moving image display and the manual display can be switched by pressing the playback switching button. Further, in the case of manual display, the reconstructed images to be displayed may be sequentially switched (frame-advanced) by the operation of the slide bar by the operation unit 32.
Although not shown, it is preferable that the screen for image inspection and the screen for image interpretation are provided with an all-image display button for displaying all the reconstructed images including the image to be deleted. This allows radiologists and radiologists to re-verify the automatically performed image selection process and respond to requests when they wish to redo image inspection and interpretation in detail from all reconstructed images. Can be done.

As described above, the tomosynthesis photographed image generation system in the present embodiment acquires the projected image of the subject a predetermined number of times while changing the positional relationship between the radiation source 61 and the radiation detector F, and the photographing means. It is a reconstructed image generation means that reconstructs a plurality of projected images to generate a reconstructed image of a subject, and deletes an image that does not satisfy a predetermined condition suitable for interpretation among the generated reconstructed images. A display that displays a reconstructed image excluding the image to be deleted and the image selected by the control unit 91, which is the deletion target image selection means selected as the target image, and the deletion target image selection means, as the display image. It has a part 93.
As a result, a radiologist who inspects the reconstructed image and a medical person such as a doctor who interprets the image based on the display image displayed on the display unit 93 can obtain an image with low sharpness that is not suitable for diagnosis. A reconstructed image (tomographic image of subject H, slice image) taken by tomosynthesis can be viewed in the excluded state. Therefore, the time required for image inspection and image interpretation can be shortened, and image inspection work and image diagnosis can be performed efficiently.
In addition, since the image to be deleted is removed from the beginning and only the image useful for image interpretation is displayed as the display image, image inspection and image interpretation are performed focusing only on the image useful for image interpretation and the like. It is expected that more accurate image inspection and interpretation can be performed while reducing the burden on medical personnel.

Further, in the present embodiment, the control unit 91 of the console 90, which is a tomosynthesis captured image selection device, functions as a deletion target image selection means, and the control unit 91 as the deletion target image selection means is used for a plurality of reconstructed images. , An image that does not meet the predetermined conditions suitable for interpretation is selected as the image to be deleted.
For this reason, it is possible to automatically delete images unsuitable for diagnosis and the like on the console 90 and provide them to medical personnel such as radiologists and doctors, which reduces the burden on medical personnel and causes trouble. Appropriate diagnostic imaging can be performed without this.

Further, in the present embodiment, the control unit 91, which is a deletion target image selection means, selects the deletion target image by analyzing and evaluating the frequency characteristics of the plurality of reconstructed images. As a result, it is possible to select an image that is not suitable for diagnosis with high accuracy by a simple method and exclude it from the display image.

Further, in the present embodiment, the control unit 91, which is the deletion target image selection means, adopts a method of analyzing the distribution state of the power spectrum according to the frequency of a plurality of reconstructed images as a method of analyzing and evaluating the frequency characteristics. .. As a result, the image to be deleted can be easily and surely selected.

Further, in the present embodiment, the control unit 91, which is a means for selecting an image to be deleted, obtains a value obtained by comprehensively analyzing any one of the imaging site, imaging direction, and patient size, or a part or all of them. Select the image to be deleted in consideration.
Depending on the imaging site, imaging direction, and patient size, the appearance of frequency characteristics may change when a reconstructed image is created, or the frequency characteristics may not appear accurately outside the region of interest Ar1.
In this regard, in the present embodiment, the region of interest Ar1 is specified according to the imaging region and the like, and the frequency characteristics of the region of interest Ar1 are analyzed and evaluated. As a result, the image to be deleted can be selected more appropriately.

Further, in the present embodiment, the control unit 91, which is the deletion target image selection means, determines whether or not a predetermined condition suitable for image interpretation is satisfied for a plurality of reconstructed images in the order of shooting time series. If there is a reconstructed image that is judged not to satisfy the predetermined condition suitable for interpretation among the reconstructed images judged to satisfy the predetermined condition suitable for interpretation, this is not regarded as the image to be deleted.
In order to perform accurate image interpretation and image diagnosis, it is preferable to see as many images suitable for image interpretation as possible. Therefore, it is important to prevent an image suitable for interpretation from being mistakenly selected as an image to be deleted.
In this respect, in the present embodiment, it is possible to prevent a part of the reconstructed image (slice image) which is continuous as a series of tomographic images of the subject H from being excluded from the target such as interpretation. This makes it possible to perform accurate and appropriate diagnostic imaging.

In this embodiment, the case where the control unit 91, which is the deletion target image selection means, selects the deletion target image by analyzing the distribution state of the power spectrum according to the frequency of the plurality of reconstructed images is illustrated. The specific method in which the control unit 91, which is the image selection means for deletion, analyzes and evaluates the frequency characteristics of the reconstructed image is not limited to the one illustrated here.
For example, the control unit 91, which is a deletion target image selection means, may select the deletion target image by analyzing and evaluating the MTF (Modulation Transfer Function) value of the plurality of reconstructed images, or may select a plurality of reconstruction targets. The image to be deleted may be selected by analyzing and evaluating the DQE (Detective Quantum Efficency) value of the constituent image.
Even when the DQE and MTF indexes are used, it is possible to distinguish between sharp images and non-sharp images by analyzing each value, and images that are not suitable for diagnosis should be appropriately selected and excluded from the display images. Can be done.

Further, the control unit 91, which is a means for selecting an image to be deleted, may select an image to be deleted by combining a plurality of reconstructed images with other evaluation values in addition to analyzing the frequency characteristics.
Specifically, for example, it is conceivable to select an image to be deleted in combination with numerical values such as SN (signal noise) ratio, histogram analysis, image analysis, and CAD (computer-aided diagnosis).
By combining various evaluation values, it can be expected that more accurate selection will be made.

[Second Embodiment]
A second embodiment of the tomosynthesis photographed image selection apparatus and the tomosynthesis photographed image generation system according to the present invention will be described with reference to FIGS. 9 to 11. In this embodiment, only the image selection process by the control unit 91, which is the deleted image selection means in the console 90, which is the tomosynthesis captured image selection device, is different from the first embodiment. The points different from the first embodiment will be described.

The control unit 91, which is a deletion image selection means in the present embodiment, selects an image to be deleted by evaluating the time when the image reader has read the plurality of reconstructed images.
Here, the interpretation broadly includes not only the interpretation by the interpretation doctor but also the image confirmation by the medical personnel such as the image inspection by the radiologist.
Further, although not shown, in the present embodiment, information about the image reader is stored in the storage unit 95.
Here, the information about the image reader is information such as the time (average time, maximum time, minimum time, etc.) required for the image reader to interpret one reconstructed image, and the storage unit 95 has these information. The information is stored in association with an ID or the like for identifying each reader.
Since the time required to interpret one reconstructed image differs for each interpreter, it is difficult to set a common threshold value for evaluating the interpretation time. In this regard, by storing the information about the image reader as described above and referring to the information when determining the threshold value of the image interpretation time, it is possible to set an appropriate threshold value in consideration of the individual difference of the image reader.
The specific contents of the image selection process will be described together with the operation with reference to FIG.

FIG. 9 is a flowchart showing an image selection process by the control unit 91 in the present embodiment.
As shown in FIG. 9, the control unit 91 first refers to the storage unit 95 to read out the imaging site, imaging direction, and patient size of the reconstructed image to be image-selected (step S21). Further, the control unit 91 reads out the information (interpreter information) of the person who performs image inspection, image interpretation, or the like on the reconstructed image from the storage unit 95 (step S22).
Then, the threshold value of the image interpretation time of the image examiner or the image reader for the reconstructed image is determined based on the information such as the imaged portion of the reconstructed image and the image reader information (step S23).
When image inspection or image interpretation is started, the control unit 91 starts measuring the image interpretation time for each reconstructed image (step S24). Then, the control unit 91 records each interpretation time for each reconstructed image each time the image inspection or interpretation is completed (step S25).

When the image inspection or interpretation of all the reconstructed images obtained in the series of shooting is completed, the control unit 91 deletes the reconstructed image whose interpretation time is shorter than the threshold value as an image that does not satisfy a predetermined condition suitable for interpretation. It is selected as the target image (step S26).
FIG. 10 illustrates a case where there are 50 reconstructed images obtained by a series of shootings to be image-examined and interpreted, and the reconstructed images are arranged on the horizontal axis in chronological order from the first image. They are lined up. The vertical axis shows the time (seconds) required for image detection / interpretation of each reconstructed image. Further, in FIG. 10, the alternate long and short dash line means the threshold value of the image interpretation time, which is approximately 1 second in the present embodiment.
In the example shown in FIG. 10, the image inspection time gradually increases from the 11th image of the reconstructed image, and the image inspection time of the 15th image is 4 seconds, which exceeds the threshold value. After that, the image inspection time fluctuates above the threshold value, but falls below the threshold value at the 35th image.
Therefore, the control unit 91 selects the reconstructed images from the 1st to 14th images and the 35th to 50th images as images to be deleted as images that do not satisfy the predetermined conditions suitable for image interpretation.

In the present embodiment, the control unit 91, which is the deletion target image selection means, determines whether or not the plurality of reconstructed images satisfy the predetermined conditions suitable for image interpretation in the order of shooting time series. Then, if there is a reconstructed image that is determined not to satisfy the predetermined condition suitable for interpretation among the reconstructed images determined to satisfy the predetermined condition suitable for interpretation, this is not regarded as the image to be deleted. The image is changed to a display image (step S27).
For example, in the example shown in FIG. 11, as in FIG. 10, the image detection time gradually increases from the 11th image of the reconstructed image, and the image detection time of the 15th image is 4 seconds, which exceeds the threshold value. However, after that, the image detection time falls below the threshold value on the 26th and 27th sheets, exceeds the threshold value again on the 28th sheet, changes above the threshold value on the 28th sheet, and falls below the threshold value again on the 35th sheet.
In this case, the 26th and 27th images do not satisfy the predetermined conditions suitable for image interpretation, but the control unit 91 also changes these to display images without setting them as deletion target images.
Similar to the first embodiment, even if some of the tomographic images (slice images) continuous in the thickness direction of the subject H along the time series do not satisfy the predetermined conditions suitable for interpretation, these are reconstructed. The image should represent one tomographic plane of subject H. The image interpretation time varies depending on the degree of fatigue of the image reader, and even if a part of the continuous image contains a short image interpretation time, it is judged that the image is not necessarily suitable for diagnosis. Can't. In this case, it is not preferable to exclude such images from the images used for interpretation. Therefore, in the present embodiment, these images are included in the display images used for interpretation.
As a result, it is possible to prevent the image constituting one tomographic surface of the subject H from being excluded from the image interpretation target.
It should be noted that the determination method for exceptionally including an image that does not satisfy the predetermined conditions suitable for image interpretation in the display image is not particularly limited, as in the first embodiment.

Since the other points are the same as those in the first embodiment, the description thereof will be omitted.

As described above, according to the present embodiment, the same effect as that of the first embodiment can be obtained, and the following effects can be obtained.
That is, in the present embodiment, the control unit 91, which is the deletion target image selection means, selects the deletion target image by evaluating the time when the image reader has read the plurality of reconstructed images. Therefore, it is possible to appropriately select the image to be deleted based on the experience of the reader.

In the present embodiment, the reconstructed image is based on the imaging site, imaging direction, patient size, and information of the person performing image inspection, interpretation, etc. (interpreter information) of the reconstructed image to be image selection processing. Although the case where the threshold value of the image interpretation time of the image examiner or the image interpreter is determined and the image to be deleted is selected depending on whether or not the threshold value is exceeded, the control unit 91 which is the deletion image selection means is the double image reader. The method of selecting the image to be deleted by evaluating the time read by the image is not limited to this.
For example, when the image inspection or interpretation of all the reconstructed images obtained in a series of shootings is completed, the control unit 91 calculates the average value of the image inspection time of each image and is constant in light of this average value. An image having a shorter interpretation time may be selected as an image to be deleted. In this case, it is possible to determine whether or not to use the image to be deleted by relative evaluation among all the reconstructed images obtained by a series of shootings, so that the threshold value for each image reader, each imaged part, etc. There is no need to acquire and remember.

In addition, the image to be deleted is a combination of the method of evaluating the time read by the image reader shown in the present embodiment and various methods of analyzing and evaluating the frequency characteristics of the reconstructed image as in the first embodiment. May be selected.
In this case, since the image to be deleted can be determined by more elements, it can be expected that the image to be deleted is selected with high accuracy.

Further, for example, when an image inspection is performed by a radiologist and then an image interpretation is performed by an image interpreting doctor, the display image may be updated every time the image interpretation is performed. In this case, images suitable for image interpretation are gradually narrowed down, so that image interpretation and image diagnosis can be performed more efficiently.

Further, in each of the above embodiments, all the reconstructed images and the images (display images) of the reconstructed images excluding the image to be deleted are separately stored (that is, the reconstructed images are stored in the storage unit 95). The display image excluding the image to be deleted from the reconstructed image is stored in the reconstructed image storage unit 952, and the display image is stored in the display image storage unit 953). The configuration for storing images excluding images is not limited to this.
For example, the determination result of whether or not the image is to be deleted may be stored in association with the reconstructed image (group) as incidental information of each reconstructed image.
In this case, since the reconstructed image is stored in the reconstructed image storage unit 952 of the storage unit 95 with the incidental information associated with it, it is not necessary to separately provide the display image storage unit 953.
In this case, since the image data is not stored in duplicate, the amount of stored image data can be reduced.

Further, in each of the above embodiments, the console 90 as the tomosynthesis captured image selection device displays a reconstructed image excluding the image to be deleted and the image selected by the control unit 91, which is the image selection means for deletion, as a display image. Although the case where the display unit 93 is provided as the display means is illustrated, it is not essential that the tomosynthesis captured image selection device (console 90 in each of the above embodiments) is provided with the display means (display unit 93).
For example, the tomosynthesis captured image selection device (console 90) does not have a display means (display unit 93), and a reconstructed image excluding the image to be deleted and the selected image is displayed on an external device (for example, PACS, etc.) equipped with a display means. ) May be used.
In this way, when transmitting the reconstructed image excluding the image to be deleted and the selected image to an external device such as PACS, (1) only the reconstructed image excluding the image to be deleted and the selected image is transmitted. Either the configuration of transmitting to an external device such as PACS, or (2) the configuration of transmitting all the reconstructed images to an external device such as PACS in a state of being associated with the incidental information of whether or not the image is to be deleted. It is also possible to take.

Further, in each of the above embodiments, the radiation detector F is a so-called portable type (also referred to as a cassette type or the like), and the radiation detector F is loaded into the detector loading unit 51 of the imaging table 50 constituting the radiography imaging device 1. Although the case of performing radiation tomography has been described above, the present invention is also applied to a so-called dedicated machine type radiation detector in which the radiation detector F is not portable and is integrally formed with the imaging table 50. It is possible to do.

Further, in each of the above-described embodiments, the radiography imaging device 1 has been described as a device that performs imaging in a lying position, but may be a device that performs imaging in a standing position.

Further, in each of the above embodiments, the radiography apparatus 1 has been described as assuming that the radiation detector F and the subject H are fixed and the radiation source 61 is moved to perform tomosynthesis imaging, but the body of the fixed subject H The radiation source 61 and the radiation detector F may be moved in opposite directions along the axial direction. Alternatively, the radiation detector F may be fixed and the subject H and the radiation source 61 may be moved. Alternatively, the radiation detector F and the subject H may be moved while the radiation source 61 is fixed.
Further, the present invention can be applied not only to the case of generating a tomographic image from the projected image obtained by tomosynthesis imaging but also to the case of generating a tomographic image from the projected image obtained by CT imaging.

Further, in the above description, an example in which a hard disk, a non-volatile memory of a semiconductor, or the like is used as a computer-readable medium of the program according to the present invention has been disclosed, but the present invention is not limited to this example. As another computer-readable medium, a portable recording medium such as a CD-ROM can be applied. A carrier wave is also applied as a medium for providing data of the program according to the present invention via a communication line.

In addition, the detailed configuration and detailed operation of each device constituting the tomosynthesis photographed image selection device and the tomosynthesis photographed image generation system can be appropriately changed as long as the gist of the invention is not deviated.

1 Radiation imaging device 50 Imaging table 51 Detector loading unit 52 Loading unit Support unit 54 Subject table 60 Radiation irradiation device 61 Radiation source 64 Radiation source moving mechanism 90 Console 91 Control unit 92 Operation unit 93 Display unit 94 Communication unit 95 Storage unit 100 Image generation system F Radiation detector H Subject

Claims (11)

Positions of a radiation source that irradiates a subject with radiation and a radiation detector in which radiation detection elements that detect radiation and generate an electrical signal are arranged in a two-dimensional manner and acquire a projected image according to the irradiated radiation. A plurality of reconstructions obtained by acquiring the projected image of the subject arranged between the radiation source and the radiation detector a predetermined number of times and reconstructing the plurality of projected images while changing the relationship. A tomosynthesis photographed image selection apparatus including a deletion target image selection means for selecting an image in which a region of interest in the image is blurred or deviated as a deletion target image. Positions of a radiation source that irradiates a subject with radiation and a radiation detector in which radiation detection elements that detect radiation and generate an electrical signal are arranged in a two-dimensional manner and acquire a projected image according to the irradiated radiation. A plurality of reconstructions obtained by acquiring the projected image of the subject arranged between the radiation source and the radiation detector a predetermined number of times and reconstructing the plurality of projected images while changing the relationship. It is provided with a deletion target image selection means for selecting an image that does not satisfy a predetermined condition suitable for interpretation as an image to be deleted.
The deletion target image selection means determines whether or not the predetermined conditions suitable for image interpretation are satisfied for the plurality of the reconstructed images in the order of shooting time, and the reconstruction determined to satisfy the predetermined conditions suitable for image interpretation. A tomosynthesis captured image selection device, characterized in that, when there is a reconstructed image between images that is determined not to satisfy a predetermined condition suitable for image interpretation, this is not set as the image to be deleted. Positions of a radiation source that irradiates a subject with radiation and a radiation detector in which radiation detection elements that detect radiation and generate an electrical signal are arranged in a two-dimensional manner and acquire a projected image according to the irradiated radiation. A plurality of reconstructions obtained by acquiring the projected image of the subject arranged between the radiation source and the radiation detector a predetermined number of times and reconstructing the plurality of projected images while changing the relationship. Regarding the image, the deletion target image selection means for selecting the image that does not satisfy the predetermined conditions suitable for interpretation as the deletion target image, and the deletion target image selection means.
A tomosynthesis captured image selection device comprising: a communication means for transmitting all the reconstructed images to an external device in a state of being associated with ancillary information as to whether or not the image is to be deleted. Any one of claims 1 to 3, wherein the deletion target image selection means selects the deletion target image by analyzing and evaluating the frequency characteristics of the plurality of the reconstructed images. Tomosynthesis photographed image selection device described in. The tomosynthesis photographed image according to claim 4, wherein the deletion target image selection means selects the deletion target image by analyzing the distribution state of the power spectrum according to the frequency of the plurality of the reconstructed images. Selection device. The tomosynthesis photographed image selection apparatus according to claim 4, wherein the deletion target image selection means selects the deletion target image by analyzing and evaluating the MTF values of the plurality of the reconstructed images. The tomosynthesis photographed image selection apparatus according to claim 4, wherein the deletion target image selection means selects the deletion target image by analyzing and evaluating the DQE values of the plurality of the reconstructed images. The method for selecting an image to be deleted is claimed from claim 4, wherein the image to be deleted is selected by combining the plurality of reconstruction images with other evaluation values in addition to the analysis of the frequency characteristics. Item 4. The tomosynthesis photographed image selection apparatus according to any one of items 7. Any of claims 1 to 8, wherein the storage means for storing the determination result of whether or not the image is a deletion target image in association with the reconstructed image as incidental information of the reconstructed image is provided. The tomosynthesis photographed image selection device according to item 1. The tomosynthesis imaging according to any one of claims 1 to 9, further comprising a communication means for transmitting the reconstructed image excluding the image to be deleted and the selected image to an external device. Image selection device. It is equipped with a radiation source that irradiates a subject with radiation, and a radiation detector in which radiation detection elements that detect radiation and generate an electric signal are arranged in a two-dimensional manner and acquire a projected image according to the irradiated radiation. An imaging means for acquiring the projected image of a subject arranged between the radiation source and the radiation detector a predetermined number of times while changing the positional relationship between the radiation source and the radiation detector.
A reconstructed image generating means that reconstructs a plurality of projected images acquired by the photographing means to generate a reconstructed image of the subject, and
Among the plurality of reconstructed images generated by the reconstructed image generating means, a deletion target image selection means for selecting an image in which a region of interest in the image is blurred or deviated as a deletion target image, and
A display means for displaying the reconstructed image excluding the image to be deleted and the image selected by the deletion target image selection means as a display image, and
Tomosynthesis image generation system equipped with.