JP6930190B2 - Radiation image analyzer and radiation imaging system - Google Patents

Description

The present invention relates to a radiographic image analysis apparatus and a radiographic imaging system including the apparatus.

Shooting a dynamic image composed of a plurality of frame images generally takes a longer shooting time than shooting a still image. For this reason, the image may be blurred as a result of the patient moving during imaging. If the image is blurred, the amount of information is insufficient and re-imaging is required, which may result in extra exposure to the patient.
On the other hand, a radiographic image capturing device that captures a dynamic image is often used in combination with a device that captures a general X-ray image. In such a case, the photographer such as an engineer has no choice but to devote most of the work time to the inspection work, and thus the determination of the necessity of re-imaging becomes an excessive burden on the photographer.

Therefore, conventionally, it is necessary to re-shoot depending on the technique of stopping shooting when it detects that there is body movement (see Patent Documents 1 and 2) and whether or not the range of blurring is within a preset allowable range. A technique for making a rejection determination (see Patent Documents 3 and 4) has been proposed.
By doing so, it is possible to immediately determine the excess or deficiency of the amount of information in the captured dynamic image, and to prompt re-imaging when the amount of information is insufficient. Therefore, it is possible to take a dynamic image having a necessary amount of information without imposing an excessive burden on the photographer.

Japanese Unexamined Patent Publication No. 2005-277804 Japanese Unexamined Patent Publication No. 2007-082907 Japanese Unexamined Patent Publication No. 2005-374517 Japanese Unexamined Patent Publication No. 2007-175138

By the way, in a dynamic image, a derivative analysis image obtained by performing a predetermined analysis process (for example, a process of extracting the difference between each signal value of two frame images arranged in time series) is used for a doctor's diagnosis. Often offered.
However, the radiographic imaging apparatus described in Patent Documents 1 to 4 determines re-imaging based on the direct state (original image) of the captured image. Here, considering the case of photographing a patient who has difficulty in contracting the lungs by using such a device, the imaging itself can be completed safely if there is no body movement or blurring of the patient. .. However, if the movement of the lungs is small, the amount of information required for analysis may be insufficient. Then, after performing the analysis process later, it becomes clear that the obtained analysis result is not sufficient and re-imaging is necessary, and the patient may have to come back again.

The present invention has been made in view of the above problems, and provides a radiation image analysis apparatus capable of immediately determining whether or not a sufficient analysis result can be obtained from a captured dynamic image. The task is to do.

In order to solve the above problems, the present invention
Radiation image analyzer
For each of a plurality of frame images of the dynamic image,-out based on the signal value of the pixel, the entire signal value, partial signal value, and the pre-analysis means for generating any one or more of preparation data of the range occupancy and ,
A determination means for determining whether or not an analysis result of a dynamic image of a target can be obtained based on the preparation data and a predetermined value generated by the pre-analysis means.
It is characterized by having an order generating means for generating a re-photographing order that requires re-imaging when it is determined that the determination means cannot obtain the analysis result of the dynamic image.

According to the present invention, it is possible to determine immediately after imaging whether or not a sufficient analysis result can be obtained from the captured dynamic image.

It is a schematic diagram of the radiation imaging system which concerns on embodiment of this invention. It is a block diagram which shows the functional structure of the radiation image analysis apparatus which comprises the radiation image taking system of FIG. It is a flowchart of the analysis process executed by the radiation image analysis apparatus of FIG. It is a conceptual diagram of the operation executed in the analysis process of FIG. It is a conceptual diagram of the operation executed in the analysis process of FIG. It is a conceptual diagram of the operation executed in the analysis process of FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.

[Configuration of radiation imaging system]
First, the configuration of the radiographic imaging system according to the embodiment of the present invention will be described. FIG. 1 is a schematic view of a radiation imaging system 1.

As shown in FIG. 1, the radiation imaging system 1 of the present embodiment includes a radiation irradiation device 2, a radiation imaging device 3, a console 4, a radiation image analysis device 5, and the like. Further, the radiological imaging system 1 is also provided with a radiological information system (hereinafter, RIS6), a picture archiving and communication system (hereinafter, PACS7), and the like, if necessary.
Each device constituting the radiation imaging system 1 conforms to the DICOM (Digital Image and Communications in Medicine) standard, and communication between the devices is performed according to DICOM.

Although not shown, the radiation irradiation device 2 includes a radiation source having a rotating anode capable of generating radiation, a filament that irradiates the rotating anode with an electron beam, a set tube voltage, a tube current, and an irradiation time (mAs value). ) Etc., equipped with a generator that irradiates a dose of radiation from a radiation source.

Although not shown, the radiation imaging apparatus 3 includes a substrate in which a plurality of radiation detection elements that accumulate charges according to a dose by receiving radiation are arranged in a two-dimensional shape (matrix), and each radiation detection element. It is equipped with a read-out circuit that reads out the electric charge accumulated in the image data, a communication unit for communicating with an external device, and transmitting image data.
Then, when the radiation imaging device 3 receives radiation from the radiation irradiation device 2 and reads out the image data, the radiation image capturing device 3 immediately transmits the image data to the outside (console 4 or the like) via the communication unit. There is.

The radiation imaging device 3 may be a so-called indirect type that includes a scintillator and detects the light emitted by the scintillator receiving radiation, or the so-called direct detection of radiation without using a scintillator or the like. It may be a direct type.
Further, the radiation image capturing device 3 may be of a cooperative type that starts imaging based on a signal from the radiation irradiation device 2, or detects irradiation of radiation by itself without a signal from the radiation irradiation device 2. It may be a non-cooperative system that starts shooting.
Further, the radiation imaging apparatus 3 may be a portable type (cassette type) used by being loaded in a holder of an imaging table (which may be for standing or lying down), or may be integrated with the imaging table. It may be a dedicated machine type.

The console 4 is communicably connected to the radiation irradiation device 2, the radiation image capturing device 3, the radiation image analysis device 5, and the like.
Then, the console 4 has various imaging conditions (for example, a part to be imaged, etc.) of the radiation irradiation device 2 and the radiation image photographing device 3 based on the photographing order from the external device (radiation image analysis device 5 or RIS6) or the operation by the user. It is possible to set conditions related to the subject, conditions related to radiation irradiation such as tube voltage, tube current, and irradiation time).
Further, when the console 4 receives the image data from the radiation image capturing device 3, the console 4 immediately transmits the image data to the radiation image analysis device 5. At that time, it is also possible to display an image (still image or dynamic image) based on the image data on the display unit.

The radiation image analysis device 5 is configured as a computer or a dedicated control device, and is communicably connected to one or more consoles 4 (radiation image capturing devices 3).
Then, the radiation image analysis device 5 can analyze the image data transmitted from the console 4 and transmit a re-imaging order or an additional imaging order to the console 4 as needed. The specific operation of the radiation image analysis device 5 will be described later.

The RIS 6 is communicably connected to the console 4 and a hospital information system (HIS) (not shown).
Then, the RIS 6 can transmit the first imaging order of the dynamic image to the console 4 based on various information (patient information, reservation information, examination information, etc.) acquired from the HIS.

The PACS 7 is communicably connected to the console 4 and the radiographic image analyzer 5.
Then, the PACS 7 can save the image data received from the console 4 and the radiographic image analysis device 5 in the database.
Further, the PACS 7 can call up the image data stored in the database based on the instruction from the console 4 and the radiation image analysis device 5 and transmit the image data to the console 4 and the radiation image analysis device 5.

[Configuration of radiation image analyzer]
Next, the details of the radiation image analysis device 5 constituting the radiation image capturing system will be described. FIG. 2 is a block diagram of the radiation image analyzer 5.

As shown in FIG. 2, the radiation image analysis device 5 of the present embodiment includes a control unit 51, a communication unit 52, a storage unit 53, an operation unit 54, and a display unit 55, and each unit is connected by a bus 56. Has been done.

The control unit 51 is composed of a CPU, RAM, and the like. The CPU of the control unit 51 reads out the system program and various processing programs stored in the storage unit 53 and expands them in the RAM in response to the operation of the operation unit 54, and analyzes processing described later according to the expanded program. The operation of each part of the radiation image analysis apparatus 5 is centrally controlled, such as executing various processes such as the above and controlling the display contents of the display unit 55.

The communication unit 52 includes a LAN adapter, a modem, a TA, and the like, and controls data transmission / reception with the console 4 and the PACS 7 and the like connected to the communication network.

The storage unit 53 is composed of a non-volatile semiconductor memory, a hard disk, or the like. The storage unit 53 stores data such as a program for executing various processes (for example, analysis processing described later) by the control unit 51, parameters necessary for executing the process by the program, processing results, or image data. These various programs are stored in the form of readable program code.

The operation unit 54 is configured to be operable by a user with a keyboard equipped with cursor keys, number input keys, various function keys, etc., a pointing device such as a mouse, etc., and is input by key operation on the keyboard or mouse operation. The instruction signal is output to the control unit 51.
The operation unit 54 may be composed of a touch panel provided on the display screen of the display unit 55. In this case, the instruction signal input via the touch panel is output to the control unit 51.

The display unit 55 is composed of a monitor such as an LCD or a CRT, and receives various images (still images or dynamic images), input instructions from the operation unit 54, data, and the like according to instructions of display signals input from the control unit 51. It is possible to display.

[Operation of radiation image analyzer]
Next, the operation of the radiation image analysis device 5 according to the present embodiment will be described. FIG. 3 is a flowchart of the analysis process executed by the radiation image analysis apparatus 5, and FIGS. 4 to 6 are conceptual diagrams of various operations executed in the analysis process.
In addition, although the frame image of the lung field region was illustrated in FIGS. It is also possible.

The control unit 51 of the radiation image analysis device 5 automatically executes the analysis process shown in FIG. 3 based on the reception of image data from the console 4. It should be noted that the operation may be executed based on the fact that the operation unit 54 has performed a predetermined operation after receiving the image data.
In the analysis process, first, the pre-analysis process is executed (step S1). In this process, one type or a plurality of types of signal value maps are generated by performing a predetermined calculation based on the signal values of the pixels for each of the plurality of frame images of the dynamic image. That is, the control unit 51 serves as a pre-analysis means in the present invention. In this embodiment, a signal value map is obtained by calculating the total signal value, the partial signal value, the range occupancy rate, and the like.

As shown in FIG. 4A, the overall signal value is obtained by setting the entire frame image of one frame image of the dynamic image as the target region R and obtaining the signal values of all the pixels forming the target region R. It is obtained by extracting the maximum value and the minimum value from each signal value, and calculating the average value and the like.
After extracting and calculating the signal value for one frame image, the same processing is sequentially performed for the other frame images (all frames of one dynamic image or a part thereof). Each maximum value, each minimum value, or each average value obtained in this way becomes a signal value map.

As shown in FIGS. 4 (b) and 4 (c), the partial signal value is a signal of all the pixels forming the target region R, with a part of the frame image of one dynamic image as the target region R. It is obtained by obtaining each value, extracting the maximum value and the minimum value from each of the obtained signal values, and calculating the average value and the like.
The target region R may be one location (for example, the entire lung field region) for one frame image as shown in FIG. 4 (b), or may be a plurality of locations (for example, as shown in FIG. 4 (c)). Blood vessels around the lungs and heart) may be set.
After extracting and calculating the signal value for one frame image, the same processing is sequentially performed for the other frame images. Each maximum value, each minimum value, or each average value thus obtained is also a signal value map.

For the range occupancy rate, after calculating the total signal value or the partial signal value of the target area R, a predetermined numerical range including the maximum value, the minimum value, or the average value of the calculated signal value is set, respectively, to form the target area R. It is obtained by calculating the ratio of the number of pixels in the numerical range set by the signal value to all the pixels.
After extracting and calculating the signal value for one frame image, the same processing is sequentially performed for the other frame images. Each occupancy rate corresponding to the maximum value thus obtained, each occupancy rate corresponding to the minimum value, or each occupancy rate corresponding to the average value also becomes a signal value map.
The one or more signal value maps obtained in the process of step S1 serve as preparation data for making various determinations in the next process.

After the process of step S1 is completed, the primary determination process is performed (step S2). In this process, it is determined whether or not it is possible to obtain a sufficient analysis result from the dynamic image of the target based on the obtained one or more signal value maps and the like. In the present embodiment, at least as shown in FIG. 5A, sufficient analysis results can be obtained by determining whether or not the difference ΔS between the signal values of the corresponding pixels between the frames is equal to or greater than a predetermined value. Determine if it is possible to obtain. In addition, the shooting information (for example, shooting purpose (inspection content), etc.) attached to the image data is referred to as necessary. That is, the control unit 51 serves as a determination means in the present invention.
By performing such processing, it is possible to determine at least whether or not it is possible to evaluate the ventilation function of the lungs (ventilation analysis) using the dynamic image of the subject.

If it is determined in the process of step S2 that the difference ΔS of the signal values is less than a predetermined value (step S2; No), it is difficult to perform any analysis including ventilation analysis, so re-imaging is performed. Is performed (step S3), and the process proceeds to the secondary determination process (step S4). That is, the control unit 51 serves as an order generation means in the present invention.
On the other hand, in the process of step S2, when it is determined that the difference ΔS of the signal values is equal to or greater than a predetermined value (step S2; Yes), at least ventilation analysis can be performed, so that the process of step S3 is not performed. Proceed to the process of step S4.

In the process of step S4, it is determined what kind of analysis result can be obtained from the dynamic image of the target based on the obtained signal value map or the like. In the present embodiment, the typical signal value map (data required for the analysis process, hereinafter referred to as the reference map) required in various analysis algorithms executed in the present analysis process, which will be described later, and the obtained signal value map are selected. The signal value map corresponding to the analysis algorithm is collated, and it is determined whether or not the obtained signal value map has a correlation with the reference map and whether or not other necessary requirements are satisfied. That is, the control unit 51 serves as a secondary determination means in the present invention.
The determination result obtained by this process is information for deriving the optimum analysis parameters used in the analysis algorithm.

As another requirement, for example, as shown in FIG. 5B, each difference vector V of the signal values between frames is continuous (upward tendency, downward tendency, stagnation from any tendency, etc.). Whether or not the curve shown by the symbol C in 5 (b) is provided, and whether or not the continuity C of the difference vector V continues over a predetermined number of frames as shown in FIG. 6 (a). Or, as shown in FIG. 6B, it is determined whether or not the continuity C of the difference vector V stably repeats the rise and fall a plurality of times throughout the entire frame.

By performing such processing, for example, it is possible to determine whether or not it is possible to evaluate the blood flow function of the lungs (blood flow analysis) using a dynamic image of the target. That is, if the continuity of the difference vector V of the signal values between frames continues for a predetermined number of frames, sufficient blood flow analysis can be performed, and if it does not continue, sufficient blood flow analysis should be performed. It is possible to judge that it cannot be done.
In particular, if the stability of ascent and descent is above a certain level, the possibility of other analysis processing such as blood flow analysis can be expected.

In the process of step S4, when it is determined that the amount of information is sufficient but the stability is insufficient, or the stability is insufficient for a certain analysis but sufficient for another analysis, etc. (step). S4; Yes) generates an additional shooting order (step S5), which requires additional shooting of the dynamic moving image (for example, shooting in a resting state to improve stability, lengthening the shooting time, etc.). The process proceeds to step S6.
On the other hand, in the process of step S4, when it is determined that the rephotographing order is generated in the preprocessing or the stability is sufficiently high and can be used for any analysis process (step S4; No), step S5. The process proceeds to step S6 without performing the process.

In determining the correlation, one signal value map may be collated with a plurality of types of reference maps corresponding to different analysis algorithms. The larger the number of correlative reference maps, the higher the quality of the analysis image that can be obtained, and the more it can be used for other types of analysis.
Further, instead of determining only the presence / absence of the correlation, for example, a stepwise determination such as a considerably high correlation, a slightly high correlation, a slightly low correlation, or a considerably low correlation may be performed.

It is also possible to make a judgment by combining an analysis grade according to the number (many) of highly correlated reference maps and shooting information (for example, shooting purpose (inspection content), etc.) attached to the image data. That is, in addition to the judgment based only on the one-to-one collation result between the signal value map and the reference map, the judgment based on the collation result and the analysis grade, the judgment based on the collation result and the shooting information, the judgment based on the analysis grade and the shooting content, Judgment based on the collation result, analysis grade, and shooting information is possible.

Further, in addition to the difference ΔS of the signal values, the amount of change between the frame images obtained from the range occupancy of each frame image calculated in the pre-analysis processing may be collated with the signal value map.
In this way, it is possible to narrow down the candidates for the optimum analysis parameter according to the amount of change from the plurality of analysis parameters used in the analysis algorithm.

When it is determined in the process of step S6 that at least one of the re-shooting order and the additional shooting order is generated (step S6; Yes), the shooting order is sent to the console 4 via the communication unit 52. The process of transmitting to is performed (step S7), and the analysis process is completed.
On the other hand, when it is determined in the process of step S6 that neither the re-shooting order nor the additional shooting order is generated (step S6; No), the main analysis of the image data is performed (step S8), and the analysis process is terminated. ..

As described above, the radiation image photographing system 1 according to the present embodiment includes a radiation irradiation device 2 that irradiates radiation and a radiation image capturing device 3 that generates image data by receiving radiation from the radiation irradiation device 2. , A dynamic image is taken by repeating irradiation of radiation and generation of image data a plurality of times, and further includes a radiation image analysis device 5 that performs a predetermined analysis process on the image data generated by the radiation image taking device 3. , The radiation image analysis device 5 performs a predetermined calculation based on the signal value of the pixel for each of the plurality of frame images of the dynamic image, thereby generating the pre-analysis means for generating the preparation data and the preparation generated by the pre-analysis means. It has a determination means for determining the analysis suitability of the dynamic image of the target based on the data, and an order generation means for generating a shooting order according to the determination result of the determination means.

As a result, if the amount of information in the image data is insufficient, a shooting order requesting reshooting is automatically generated, and additional shooting is requested when the possibility of other analysis is expected in addition to the original analysis. Additional shooting orders are automatically generated. Depending on whether or not such a shooting order is transmitted to the console 4, it is possible to determine immediately after shooting whether or not a sufficient analysis result can be obtained from the captured dynamic image.

1 Radiation imaging system 2 Radiation irradiation device 3 Radiation imaging device 4 Console 5 Radiation image analysis device 51 Control unit (pre-analysis means, judgment means, order generation means, secondary judgment means)
52 Communication unit 53 Storage unit 54 Operation unit 55 Display unit 56 Bus 6 Radiological information system (RIS)
7 Picture Archiving and Communication Systems (PACS)

Claims (8)

For each of a plurality of frame images of the dynamic image,-out based on the signal value of the pixel, the entire signal value, partial signal value, and the pre-analysis means for generating any one or more of preparation data of the range occupancy and ,
A determination means for determining whether or not an analysis result of a dynamic image of a target can be obtained based on the preparation data and a predetermined value generated by the pre-analysis means.
A radiation image analysis apparatus comprising: an order generating means for generating a re-imaging order requesting re-imaging when it is determined that the determination means cannot obtain an analysis result of the dynamic image. .. The pre-analysis means
Maximum, minimum and average values of the signal values of all pixels forming one frame image,
Maximum, minimum and average values of the signal values of all pixels forming the region of interest of one frame image,
The radiographic image analysis according to claim 1, wherein at least one of the ratio of the number of pixels whose signal value is within a predetermined numerical range to all the pixels forming the region of interest is calculated as the preparatory data. Device. It said determining means, maximum value of the signal values of all pixels forming one frame image of the pre-analysis means is generated by using the minimum value and the average value, the difference between the signal value between frame images the predetermined value or more The radiographic image analysis apparatus according to claim 1 or 2, wherein it is determined whether or not the radiation image analysis apparatus is used. The determination means uses the maximum value, the minimum value, and the average value of the signal values of all the pixels forming a part region of one frame image generated by the pre-analysis means, and the difference in the signal values between the frame images is determined. radiation image analysis apparatus according to claim 1 or 2, characterized in that determining whether the a predetermined value or more. After the difference signal value between said determining means frame image is judged whether it is the predetermined value or more, by collating information and necessary for analysis and preparation data the pre-analysis means is generated,
Whether or not the difference vector indicating the difference in signal values between frames has continuity,
Whether or not the continuity of the difference vector continues over a predetermined number of frames
3. Radiation image analyzer. The radiation image analysis apparatus according to claim 5, wherein the secondary determination means collates the preparation data with information on inspection contents included in the image data of the dynamic image. The secondary determination means is
A predetermined numerical range including the maximum value, the minimum value, or the average value of the signal value calculated by the pre-analysis means is set, respectively.
For each of a plurality of frame images of the dynamic image, the total pixels forming the part area, calculates a ratio of the number of pixels that are within the numerical range which the signal value is set,
The radiographic image analysis apparatus according to claim 5 or 6, wherein the prepared data is collated with the amount of change of the ratio for each frame image. A radiation irradiation device that irradiates radiation, and
A radiation imaging device that generates image data by receiving radiation from the radiation irradiation device, and
It is a radiation imaging system that captures dynamic images by repeating irradiation of radiation and generation of image data multiple times.
A radiographic imaging system further comprising the radiographic image analysis apparatus according to any one of claims 1 to 7.

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