JP2016209267A - Medical image processor and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a person who performs photographing to quickly determine whether or not re-photography is necessary in photography of a radiation image for energy subtraction processing.SOLUTION: A control unit 51 of a photography console 5 performs difference processing of a plurality of radiation images acquired by irradiating an identical subject with radiation of two different kinds of energy at different timing and generates information about a motion artifact on the difference images caused by motions of a structure in the subject by analyzing the generated difference images or the plurality of radiation images, and displays difference images and the information about the motion artifact on the difference images on a display 54.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a medical image processing apparatus and a program.

  Conventionally, by using the fact that the attenuation amount of the transmitted radiation is different depending on the substance constituting the subject, by performing differential processing on a plurality of radiation images obtained by irradiating the subject with radiation of two different types of energy A so-called energy subtraction process for generating a difference image is known. Using this energy subtraction process, for example, by generating a soft part image (soft tissue image) by removing the bone part from the chest image, it is possible to observe the shadow that appears in the soft part without being disturbed by the bone It becomes. Conversely, by generating a bone part image from which the soft part is removed, it is possible to observe the shadow appearing on the bone part without being disturbed by the soft part.

  Imaging of radiation images of two types of energy used for energy subtraction processing is performed by irradiating a subject with high energy radiation and low energy radiation at intervals of several hundred millisec. However, even in the case of several hundred millimeters Sec, there is a possibility that the structure in the subject moves because the shooting interval is long. In the chest, at least due to the pulsation of the heart, a large change occurs in blood vessel structures such as the heart and pulmonary blood vessels between the two radiographic images. As a result, motion artifacts occur in the heart and lung fields of the difference image (the soft part image and the bone part image described above) obtained by the energy subtraction process.

Therefore, for example, Patent Document 1 describes that a heartbeat phase of a subject is detected using an electrocardiograph or the like, and the subject is X-rayed when the detected phase matches a heartbeat phase in a past image. Yes.
Japanese Patent Laid-Open No. 2004-26883 discloses that alignment is performed using warping or the like on either a high energy image or a low energy image, and energy subtraction processing is performed using the aligned high energy image and low energy image. Have been described.
Further, Patent Document 3 includes a plurality of first band images and second band images representing structures having different frequency bands for the first and second radiographic images captured by radiations of different energies. It is described that the amount of displacement of the first and second band images is generated. Then, the second band image is deformed based on the obtained positional deviation amount to align the first and second band images, and the deformed second band image is reconstructed and deformed. And generating a soft part image and a bone part image with reduced artifacts by performing energy subtraction processing using the first radiation image and the deformed second radiation image. ing.

JP 2005-312007 A JP 2011-250969 A JP 2011-255060 A

  However, as described in Patent Document 1, it is difficult to capture images so that the heartbeat phases are completely the same. Further, in facilities that perform imaging of a large number of patients, such as a facility that conducts a medical examination, it is complicated to install an apparatus such as an electrocardiograph, which reduces the efficiency of imaging.

  Further, as described in Patent Documents 2 and 3, even if the positional deviation of the structure between images, which is a cause of motion artifacts, is corrected by warping or the like, correction may not be possible depending on the degree of motion artifacts. . Further, when the alignment fails, unnecessary artifacts may occur due to the failure.

  The appearance degree of the motion artifact varies depending on the timing of the heart movement and the timing of photographing between images. Therefore, motion artifacts that cannot be corrected by correction may be significantly reduced by re-imaging. Since re-imaging takes time and cost once the patient is returned, it is preferable to immediately determine whether or not re-imaging is necessary. However, whether a photographer such as a radiographer sees the captured image and immediately identifies the area where the motion artifact occurs, and whether or not the level is at a level where clinical operation is possible (level at which doctors can interpret) It is difficult to judge.

  An object of the present invention is to enable a radiographer to quickly determine whether or not re-imaging is necessary in radiographic imaging for energy subtraction processing.

In order to solve the above-mentioned problem, the invention described in claim 1
In a medical image processing apparatus that generates a difference image by performing a difference process on a plurality of radiation images obtained by irradiating radiation of two different types of energy to the same subject at different timings,
Analyzing the difference image or the plurality of radiation images to generate information on motion artifacts on the difference image resulting from the movement of the structure in the subject;
Display means for displaying information on the difference image and motion artifacts on the difference image;
Is provided.

The invention according to claim 2 is the invention according to claim 1,
The analysis means analyzes the difference image to identify a motion artifact occurrence region on the difference image caused by the movement of the structure in the subject and generate information indicating the motion artifact occurrence region And
The display means displays information indicating a motion artifact occurrence region on the difference image.

The invention according to claim 3 is the invention according to claim 1,
The analysis means calculates a movement amount of the structure in the subject between the plurality of radiation images by analyzing the plurality of radiation images, and based on the calculated movement amount, Generating information indicating the generation area of the motion artifact on the difference image due to the movement of the structure of
The display means displays information indicating a motion artifact occurrence region on the difference image.

The invention according to claim 4 is the invention according to any one of claims 1 to 3,
Setting means is provided for setting an analysis target region to be analyzed in the difference image or the plurality of radiation images.

The invention according to claim 5 is the invention according to any one of claims 1 to 4,
The analysis unit generates information indicating the strength of motion artifacts on the difference image due to the movement of the structure in the subject by analyzing the difference image,
The display means displays the difference image and information indicating the strength of motion artifact on the difference image.

The invention according to claim 6 is the invention according to claim 5,
With operating means,
The display means enlarges and displays the area designated by the operation means on the difference image, and displays information indicating the strength of the motion artifact in the enlarged display area.

The invention according to claim 7 is the invention according to claim 5 or 6,
The information indicating the strength of the motion artifact is obtained by normalizing the pixel signal value profile in the designated area of the difference image and / or the pixel signal value of the radiation image before the difference at the same position as the profile. The difference value from the profile obtained is a value equal to or greater than a predetermined threshold value.

The invention according to claim 8 is the invention according to any one of claims 1 to 7,
An acquisition unit that acquires the past difference image from a storage unit that stores the past difference image of the subject generated before the difference image;
The display means displays the difference image and the past difference image side by side.

The invention according to claim 9 is the invention according to claim 8,
The display means further displays information on motion artifacts on the past difference image generated by analyzing the past difference image of the subject by the analysis means.

The invention according to claim 10 is the invention according to any one of claims 1 to 9,
Input means for inputting an instruction to re-photograph the plurality of radiation images.

The invention according to claim 11
In a medical image processing apparatus that generates a difference image by performing a difference process on a plurality of radiation images obtained by irradiating radiation of two different types of energy to the same subject at different timings,
An acquisition means for acquiring the past difference image from a storage means for storing a past difference image of the subject generated before the difference image;
Display means for displaying the difference image and the past difference image;
An input means for inputting an instruction for re-imaging the plurality of radiation images;
Is provided.

The invention according to claim 12 is the invention according to claim 8 or 11,
The past difference image is associated with information on motion artifacts of the past difference image,
The acquisition means acquires information on motion artifacts of the past difference image together with the past difference image,
The display means further displays information related to motion artifacts of the past difference image.

The invention according to claim 13 is the invention according to claim 12,
The information regarding the motion artifact of the past difference image includes a comment regarding the motion artifact in the past difference image by a reader of the past difference image.

The program of the invention according to claim 14 is:
A computer used for a medical image processing apparatus that generates a differential image by performing differential processing on a plurality of radiographic images acquired by irradiating radiation of two different types of energy to the same subject at different timings,
Analyzing means for generating information on motion artifacts on the difference image resulting from the movement of the structure in the subject by analyzing the difference image or the plurality of radiation images;
Display means for displaying information on the difference image and motion artifact on the difference image;
To function as.

The program of the invention according to claim 15 is:
A computer used for a medical image processing apparatus that generates a differential image by performing differential processing on a plurality of radiographic images acquired by irradiating radiation of two different types of energy to the same subject at different timings,
An acquisition means for acquiring the past difference image from a storage means for storing a past difference image of the subject generated before the difference image;
Display means for displaying the difference image and the past difference image;
Input means for inputting an instruction for re-imaging the plurality of radiation images;
To function as.

  According to the present invention, it is possible for a shooter to quickly determine whether or not re-shooting is necessary in shooting for energy subtraction processing.

1 is a diagram illustrating an overall configuration of a medical image photographing system according to an embodiment. It is a block diagram which shows the functional structure of the imaging | photography console. It is a flowchart which shows the imaging | photography control processing A performed by the control part of an imaging | photography console. It is a figure for demonstrating an artifact value. It is a figure which shows the relationship between a motion artifact and the moving amount | distance of a structure. It is a figure which shows an example of the screen where the difference image and the motion artifact information were displayed. It is a figure which shows an example of the screen where the difference image and the motion artifact information were displayed. FIG. 7 is a diagram illustrating an example in which a region designated in FIG. 6 is enlarged and a signal value profile in the designated region is displayed. 9 is a flowchart illustrating a shooting control process B executed by a control unit of a shooting console in the second embodiment. It is a figure which shows an example of the screen displayed on a display part in FIG.9 S28. 10 is a flowchart illustrating a shooting control process C executed by a control unit of a shooting console in the third embodiment.

  Hereinafter, embodiments of a medical image photographing system according to the present invention will be described with reference to the drawings. However, the present invention is not limited to the following illustrated examples.

<First Embodiment>
(Configuration of medical imaging system)
First, the configuration of the medical image photographing system 100 in the present embodiment will be described.
FIG. 1 is a diagram showing an overall configuration example of a medical image photographing system 100 according to an embodiment of the present invention. FIG. 1 shows a case where the medical image photographing system 100 is constructed in the photographing room Rm. The medical imaging system 100 performs a so-called energy subtraction process in which a subject is irradiated with radiation of two different types of energy to acquire a plurality of radiation images and a differential image of the acquired plurality of radiation images is generated. It is. In this embodiment, the X-ray tube voltage (hereinafter referred to as tube voltage) is changed (for example, a high tube voltage of 100 to 140 kVp and a low tube voltage of 50 to 80 kVp), and the chest and abdomen are imaged twice. A description will be given assuming that two radiographic images of a high energy image and a low energy image are acquired.

  In the photographing room Rm, for example, a bucky device 1 for standing photographing, a bucky device 2 for standing photographing, a radiation source 3, a photographing console 5, an operation console 6, and an access point AP are provided. Is provided. The photographing room Rm is provided with a front room Ra and a photographing room Rb, and the front room Ra is provided with a photographing console 5 and a console 6 to prevent exposure of a photographing person such as a photographing engineer. ing.

Hereinafter, each device in the photographing room Rm will be described.
The bucky device 1 is a device for holding an FPD (Flat Panel Detector) 9 and performing shooting when shooting in a standing position. The bucky device 1 includes a holding portion 12a for holding the FPD 9 and a connector 12b for connecting a connector of the FPD 9 attached to the holding portion 12a. The connector 12b transmits / receives data to / from the FPD 9 attached to the holding unit 12a and supplies power to the FPD 9. The bucky device 1 also has an interface for transmitting / receiving data to / from an external device such as the imaging console 5 via the access point AP via a communication cable, and for moving the holding unit 12a vertically or horizontally. A foot switch is provided.

  The bucky device 2 is a device for holding the FPD 9 when shooting in the supine position. The bucky device 2 includes a holding portion 22a for holding the FPD 9 and a connector 22b for connecting a connector of the FPD 9 attached to the holding portion 22a. The connector 22b transmits / receives data to / from the FPD 9 attached to the holding unit 22a and supplies power to the FPD 9. The bucky device 2 also includes an interface for transmitting / receiving data to / from an external device such as the imaging console 5 via a communication cable via an access point AP, and a subject table 26 for placing a subject.

  For example, the radiation source 3 is suspended from the ceiling of the imaging room Rm, and is activated based on an instruction from the imaging console 5 at the time of imaging, and is adjusted to a predetermined position and orientation by a driving mechanism (not shown). It has become. Then, by changing the irradiation direction of radiation, radiation (X-rays) can be irradiated to the FPD 9 mounted on the standing-side bucky device 1 or the lying-down bucky device 2. . In addition, the radiation source 3 irradiates radiation twice with different tube voltages in accordance with the radiation irradiation instruction from the console 6 to take a high energy image and a low energy image.

  The imaging console 5 controls imaging by controlling the radiation source 3 and the FPD 9, and performs difference processing on the image generated by imaging to generate a differential image (soft part image, bone part image) and re-photograph. It is a medical image processing apparatus for displaying for confirmation of necessity. The imaging console 5 is connected to a HIS / RIS (Hospital Information System / Radiology Information System) 7, a diagnostic console 8, a server device 10, etc. via a LAN (Local Area Network), and is transmitted from the HIS / RIS 7. Based on the inspection order information, the radiation source 3 and the FPD 9 are controlled to perform imaging.

  FIG. 2 shows a configuration example of a main part of the imaging console 5. As shown in FIG. 2, the photographing console 5 includes a control unit 51, a storage unit 52, an operation unit 53, a display unit 54, a communication I / F 55, a network communication unit 56, and the like. 57 is connected.

The control unit 51 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), and the like. The CPU of the control unit 51 reads out various programs such as system programs and processing programs stored in the storage unit 52, expands them in the RAM, and executes various processes according to the expanded programs.
For example, the control unit 51 makes an inquiry to the HIS / RIS 7 via the network communication unit 56 every predetermined time, and acquires inspection order information newly registered in the HIS / RIS 7.
For example, the control unit 51 executes a shooting control process A described later. The control unit 51 functions as an analysis unit.

The storage unit 52 includes, for example, an HDD (Hard Disk Drive), a semiconductor nonvolatile memory, or the like.
The storage unit 52 stores a system program executed by the control unit 51, various programs including an imaging control processing program, and data necessary for executing these programs. Various programs are stored in the storage unit 52 in the form of computer-readable program code, and the control unit 51 sequentially executes operations according to the program code.

The storage unit 52 stores imaging conditions (radiation irradiation conditions and image reading conditions) in association with imaging regions. The radiation irradiation conditions are, for example, the value of the X-ray tube current, the value of each tube voltage when performing two imaging operations for energy subtraction, the filter type, the SID (Source to Image-receptor Distance), and the like.
In addition, the storage unit 52 stores inspection order information transmitted from the HIS / RIS 7 every predetermined time.

  The operation unit 53 includes a keyboard having character input keys, numeric input keys, various function keys, and the like, and a pointing device such as a mouse, and a key pressing signal pressed by the keyboard and an operation signal by the mouse. Are output to the control unit 51 as an input signal. The operation unit 53 functions as an operation unit and an input unit.

The display unit 54 includes, for example, a monitor such as a CRT (Cathode Ray Tube) or an LCD (Liquid Crystal Display), and displays various screens according to instructions of a display signal input from the control unit 51.
A pressure-sensitive (resistive film pressure type) touch panel (not shown) in which transparent electrodes are arranged in a grid pattern is formed on the screen of the display unit 54, and the display unit 54 and the operation unit 53 are configured integrally. It may be a touch screen. In this case, the touch panel is configured to detect the XY coordinates of the power point pressed by a finger, a touch pen, or the like as a voltage value, and output the detected position signal to the control unit 51 as an operation signal. The display unit 54 may have a higher definition than a monitor used in a general PC (Personal Computer).

  The communication I / F 55 is an interface for connecting to the Bucky device 1, the Bucky device 2, the radiation source 3, and the FPD 9 via the access point AP and performing data transmission / reception wirelessly or by wire. In the present embodiment, the communication I / F 55 transmits a polling signal to the FPD 9 as necessary via the access point AP.

  The network communication unit 56 includes a network interface or the like, and transmits / receives data to / from an external device connected to the communication network N via a switching hub.

  The console 6 is an input device that is connected to a radiation source in the imaging room and inputs a radiation irradiation instruction.

  The HIS / RIS 7 generates inspection order information in accordance with a registration operation by an operator based on an inquiry result or the like. The examination order information includes, for example, patient information such as the name, sex, age, height, weight, etc. of the patient to be the subject, identification information for identifying the examination (examination ID), imaging part, modality type, imaging date, It includes information related to imaging in examinations such as imaging direction (front, side), body position (standing position, lying position), and imaging method. In addition, inspection order information is not limited to what was illustrated here, Information other than this may be included, and a part of information illustrated above may be sufficient.

  The diagnosis console 8 is a computer device that acquires medical images from the server device 10 and displays the acquired images to allow a doctor to make an interpretation diagnosis.

The FPD 9 is a radiation detector that includes a control unit, a detection unit, a storage unit, a connector, a battery, a wireless communication unit, and the like.
The detection unit of the FPD 9 includes, for example, a glass substrate, and detects, at a predetermined position on the substrate, radiation that has been irradiated from the radiation source 3 and transmitted through at least the subject according to the intensity thereof. A plurality of detection elements that are converted into electrical signals and accumulated are two-dimensionally arranged. The detection element is configured by a semiconductor image sensor such as a photodiode. Each detection element is connected to a switching unit such as a TFT (Thin Film Transistor), for example, and the switching unit controls the accumulation and reading of electric signals.

The control unit of the FPD 9 controls the switching unit of the detection unit based on the image reading condition input from the imaging console 5 to switch the reading of the electrical signal accumulated in each radiation detection element (hereinafter, detection element). Then, image data is generated by reading the electrical signal stored in the detection unit. Then, the control unit outputs the generated image data to the photographing console 5 via the connector and the bucky device 1 or 2. The signal value of each pixel constituting the generated image data indicates a signal value (here, a density value) output from each detection element of the detection unit.
The connector of the FPD 9 is connected to the connector on the Bucky devices 1 and 2 side, and performs data transmission / reception with the Bucky device 1 or 2. The connector of the FPD 9 supplies power supplied from the connector of the bucky device 1 or 2 to each function unit. Note that the battery may be charged.
Further, the FPD 9 is configured to perform battery drive and wireless communication when used alone without being attached to the Bucky. When the FPD 9 is loaded into the Bucky device 1 or 2, the battery / wireless method is switched from the battery / wireless method to the wired / power supply method by connecting the connector. Can do. Accordingly, even when a plurality of patients are continuously photographed, it is not necessary to worry about running out of the battery.

  The server device 10 includes a medical image (radiation image (high energy image, low energy image), difference image (soft part image, bone part image)), motion artifact information (details will be described later), and medical use transmitted from the imaging console 5. The incidental information related to the image is associated and stored in the database. Further, the server device 10 reads a medical image from the database in response to a request from the diagnostic console 8 and transmits the medical image to the diagnostic console 8, and a diagnostic result or comment on the medical image according to a request from the diagnostic console 8 The database is updated by writing the information to the accompanying information stored in association with the medical image.

  Here, the medical image transmitted from the imaging console 5 is image data in a DICOM file format conforming to the DICOM (Digital Imaging and Communication in Medicine) standard. The DICOM file is composed of an image part and a header part. Actual data of the medical image is written in the image portion, and supplementary information related to the medical image is written in the header portion.

The incidental information includes, for example, patient information, examination information, and detailed image information. The patient information includes patient identification information (for example, patient ID) for identifying a patient as a subject, and various types of information related to a patient in a medical image, such as the patient's name, sex, and date of birth.
The examination information includes examination identification information for identifying the examination (for example, examination ID), imaging part, modality type, imaging date, imaging direction (front, side), body position (standing position, lying position), imaging method, etc. This includes information related to photographing in the inspection.
The detailed image information includes various information related to the image such as the image number, the image generation time, the imaging conditions, the diagnosis result, and the commenter's comment information.

(Shooting operation)
Next, a photographing operation in the medical image photographing system 100 will be described.
FIG. 3 shows a flow of the shooting control process A executed in the shooting console 5. The imaging control process A in FIG. 3 is executed in cooperation with the control unit 51 of the imaging console 5 and the program stored in the storage unit 52, with the subject's chest and abdomen as subjects.

  First, the photographer sets the FPD 9 in the Bucky device 1 or the Bucky device 2. Next, the operation unit 53 of the imaging console 5 is operated to display on the display unit 54 an inspection order list screen for displaying a list of inspection order information. Then, by operating the operation unit 53, from the examination order list screen, the examination order information to be imaged (here, the examination order information in which the imaging region is the chest and abdomen and the imaging direction is the front) and the Bucky ID used for imaging are displayed. specify.

  In the imaging console 5, when inspection order information and a Bucky ID to be imaged are designated by the operation unit 53 (Step S <b> 1), the radiation source 3 and the FPD 9 are activated, and the radiation source 3 is used according to the used Bucky device. Is adjusted in direction and position. When the position of the FPD 9 or the bucky device is adjusted according to the subject by the radiographer, the direction and position of the radiation source 3 are adjusted accordingly (step S2). Further, the radiation irradiation condition and the image reading condition corresponding to the imaging part are read from the storage unit 52, the radiation irradiation condition is set in the radiation source 3, and the image reading condition is set in the FPD 9 via the Bucky device. (Step S3). When preparation for imaging is complete, the imaging operator operates the console 6 to input a radiation irradiation instruction.

  When a radiation irradiation instruction is input from the console 6 (step S4; YES), the radiation source 3 and the FPD 9 used for imaging are controlled, and the subject is imaged twice continuously with different tube voltages. (Step S5). Specifically, a subject is photographed with a high tube voltage and a low tube voltage, and two radiation images of a high energy image and a low energy image are acquired. Image data of a high energy image and a low energy image acquired by imaging is input from the FPD 9 to the imaging console 5 via the Bucky device, and stored in association with inspection order information and imaging conditions (including tube voltage information). Stored in the unit 52.

Next, difference processing (soft part image, bone part image) is generated by performing difference processing using the high energy image and the low energy image obtained by the two shootings (step S6), and the process proceeds to step S7. . In step S6, a difference processing is performed using the high energy image and the low energy image, thereby generating a soft part image representing the soft part of the subject from which the bone has been removed and a bone part image representing the bone part of the subject. For example, as shown in the following (Equation 1), the soft part image includes pixels corresponding to a high energy image obtained by integrating the first weighting factor α1 and a low energy image obtained by integrating the second weighting factor β1. Can be generated from the difference between the signal values. SP is a signal value of the soft part image, H is a signal value of the high energy image, L is a signal value of the low energy image, and γ1 is a predetermined offset value.
SP = α1 · H−β1 · L + γ1 (Formula 1)
Further, the signal value (BP) of the bone part image can be generated by the same calculation as that for the soft part image, as shown in (Expression 2).
BP = α2 · H−β2 · L + γ2 (Formula 2)

  The image data of the difference image generated by the difference process is stored in the storage unit 52 in association with the inspection order information and the imaging conditions (including tube voltage information).

  When the difference processing ends, image analysis is performed, and motion artifact information on the difference image is generated (step S7). The motion artifact information is information on motion artifacts caused by movement of a subject (in particular, a structure in the subject (in the chest, an organ such as heart, lung, blood vessel, and diaphragm)). The motion artifact information includes, for example, information indicating the strength of the motion artifact on the difference image (signal value profile, artifact value), information indicating the region where the motion artifact is generated, and the like.

  It should be noted that a difference image (soft part image, bone part image, soft part image and bone part image) to be generated of motion artifact information, and an analysis target region (entire lung field, only around the heart) are operated by the user (that is, taken around the heart). Can be set in advance. By setting the difference image to be generated in advance, generation of unnecessary difference images other than the difference image used by the interpretation doctor for interpretation can be omitted, and the processing time can be shortened. In addition, by setting the analysis target area in advance, for example, when there are many examinations of healthy subjects and the moving structure is only the heart (the diaphragm and the like do not move), only the periphery of the heart is analyzed. By doing so, the calculation time for the analysis can be shortened. Further, in the case of a patient whose breathing is difficult to stop, if the entire lung field is set as the analysis target region, not only the heart but also information on motion artifacts caused by the movement of the diaphragm and the like can be obtained. The set information is stored in the storage unit 52 (when no setting is input, default setting information is stored). Alternatively, an area where motion artifacts are likely to occur due to the movement of a structure such as the heart or the diaphragm may be stored in advance in the storage unit 52 as information, and the area may be set as an analysis target area.

Signal value profiles (hereinafter referred to as signal value profiles) include a one-dimensional signal value profile and a two-dimensional signal value profile.
A one-dimensional signal value profile, for example, recognizes a lung field region from a difference image, and if the analysis target region is only around the heart, analyzes it at the inner center edge of the left and right lung fields among the recognized lung fields. If the target area is the entire area, place profile lines on the edges of the left and right lung fields so as to avoid ribs, and display the pixel signal values on each of the placed profile lines, with the horizontal axis as the distance from the start point of the profile line. It can be generated by plotting on a graph with the vertical axis as the signal value.
The two-dimensional signal value profile is, for example, a curved profile that can be generated by generating and connecting a plurality of one-dimensional signal value profiles in a direction orthogonal to the direction of the one-dimensional signal value profile. is there.
A known method can be used for recognizing the lung field region. For example, in the subject area of the soft part image, a threshold value is obtained from the histogram of the signal value of each pixel by discriminant analysis, and a region having a signal higher than this threshold value is first extracted as a lung field region candidate. Next, edge detection is performed near the boundary of the first extracted lung field region candidate, and the boundary of the lung field region can be recognized by extracting along the boundary the point where the edge is maximum in a small region near the boundary. it can. Further, the rib region can be recognized by a technique such as performing edge detection on the bone part image and applying a curve fitting function after the edge detection. Here, the positions of the lung field region and the rib region are the same in both the soft part image and the bone part image. The layout of the profile line may be automatically performed, or the analysis target image may be displayed on the display unit 54 and designated by the user using the operation unit 53.

The difference between the artifact value and the approximate signal value generated from the signal value of the radiographic image before the difference (for example, the signal value normalized by the following (Equation 3)) in the difference image is significantly large (specifically Is a difference value from the approximate signal value at a position where the difference is equal to or greater than a predetermined threshold.
For example, if the analysis target area is only around the heart, the ribs are located on the inner center edge of the left and right lung fields among the recognized lung fields. As shown in FIG. 4, a one-dimensional signal value profile of the difference image is generated on each profile line, and at the same position as the generated one-dimensional signal value profile. A one-dimensional signal value profile of the radiation image (high energy image and / or low energy image) before the difference is generated, and the one-dimensional signal value profile of the generated radiation image before the difference is converted to the one-dimensional signal value of the difference image. It is deformed (normalized) so that the difference is smaller than the profile, and the signal difference (absolute value) between the one-dimensional signal value profile of the difference image and the modified one-dimensional profile It calculates a value equal to or greater than a predetermined threshold as artifact value (shown by an arrow in FIG. 4). For example, the maximum value among the calculated artifact values is set as the artifact value to be displayed. Note that the deformation of the signal value profile of the radiographic image before the difference can be performed by the following (Equation 3).
(Formula 3)
Deformed profile signal value = image value before difference × coefficient a + constant b

  Alternatively, the artifact value may be calculated using a two-dimensional signal value profile. For example, first, if the analysis target region is only around the heart, it will be on the inner center edge of the left and right lung fields, and if the analysis target region is the whole, it will be on the left and right lung field edges. The profile lines are arranged so as to avoid the ribs, and a one-dimensional signal value profile of the difference image is generated on each profile line. Next, a two-dimensional profile (curved surface profile) is generated by generating a plurality of rows of signal value profiles in a direction orthogonal to the direction of the generated one-dimensional signal value profile. Next, a two-dimensional signal value profile of the radiation image (high energy image and / or low energy image) before the difference is generated at the same position as the generated two-dimensional signal value profile, and two of the generated radiation image before the difference are generated. The dimensional signal value profile is deformed (normalized) so that the difference is smaller than the two-dimensional signal value profile of the difference image. The deformation can be performed by (Equation 3). Then, a signal difference (absolute value) between the two-dimensional signal value profile of the difference image and the deformed two-dimensional profile that is equal to or greater than a predetermined threshold value is calculated as an artifact value. For example, the maximum value among the calculated artifact values is set as the artifact value of the display target to be displayed.

  For example, a method using the above-described artifact value, a method of specifying based on a moving amount of a structure in a high energy image and a low energy image, and the like can be used to specify the motion artifact generation region.

  In the method of specifying using the artifact value, the area surrounding the range surrounded by the two outermost points excluding the artifact value of the isolated point is specified as the motion artifact generation area. To do.

  In the method of specifying based on the moving amount of the structure, first, a local region of one image of a high energy image or a low energy image is cut out as a template, and a place corresponding to the template is searched on the other image. The amount of movement of the structure between the two images is calculated by obtaining the amount of movement of the local region (shift vector distance). Then, an area where the calculated movement amount is equal to or greater than a predetermined threshold is specified as a motion artifact occurrence area. Although the movement amount may be obtained for each pixel, it is preferable that control points are arranged in a grid pattern on the image in consideration of calculation efficiency and target accuracy, and the movement amount on the control point is obtained.

Here, the moving amount of the structure between the high energy image and the low energy image correlates with the motion artifact in the difference image. FIG. 5 shows the relationship between the motion artifact and the moving amount of the structure. Lv_0 in FIG. 5 is a signal value profile of a heart edge of a difference image (here, a soft part image) generated by performing a difference process on a high / low energy image having the same arrangement of structures in a subject. is there. Lv_1 is a signal value profile of the heart edge of the soft part image generated by moving the signal value profile of the low energy image by one signal in the right direction and performing difference processing. Lv_2 is a signal value profile of the heart edge of the soft part image generated by moving the signal value profile of the low energy image by two signals in the right direction and performing difference processing. Lv_3 is a signal value profile of the heart margin of the soft part image generated by moving the signal value profile of the low energy image by three signals in the right direction and performing the difference process. A region surrounded by A in FIG. 5 is a portion corresponding to the boundary position of the heart. As shown in FIG. 5, as the amount of movement of the signal value profile is increased, the signal is unnaturally amplified in the soft part image obtained by the difference processing, and partial signal enhancement (motion artifact) is increased. I understand that. In other words, the movement amount of the structure between the radiation images before the difference and the motion artifact on the difference image have a relationship of “movement amount∝motion artifact”, and the motion artifact is detected in a region where the movement amount of the structure is large. It can be replaced with the generated area.
Here, the case where the soft part image is generated by moving the signal value profile of the low energy image is shown as an example, but the same relationship can be obtained when the signal value profile of the high energy image is moved. The same relationship can be obtained when a signal value profile of a bone part image is generated as a difference image.

  When the generation of the motion artifact information is completed, the difference image and the motion artifact information are displayed on the display unit 54 (step S8).

In step S8, for example, as shown in FIGS. 6 and 7, first, the region where the motion artifact specified in step S7 is generated is surrounded by annotations and displayed on the display unit 54. For example, as shown in FIG. 6, the area where the motion artifact is generated may be displayed by being surrounded by a rectangle or the like, or may be displayed by roughly surrounding the area as shown in FIG. . In this way, by indicating the area where the motion artifact is occurring on the difference image, the imaging operator can quickly identify the area where the motion artifact is occurring on the difference image and the degree of motion artifact is clinical. It is possible to confirm whether or not the operational level is possible, and it is possible to quickly determine whether or not re-shooting is necessary.
When any one of the areas surrounded by the annotation is designated by the operation of the operation unit 53 by the user, as shown in FIG. 8, the control unit 51 enlarges the designated area and displays the designated area within the designated area. Display signal value profile and / or artifact value. FIG. 8 shows an example in which the signal value profile in the designated area is displayed. For example, the signal value profile and / or artifact value having the highest artifact value among the signal value profiles in the designated region may be displayed, or the signal value profile profile in the designated region generated in step S7. The line may be displayed, and the signal value profile and / or artifact value of the profile line selected by the operation of the operation unit 53 by the photographer may be displayed. Since the signal value profile visualizes and shows the spatial change of the signal value, the user can check how much the signal is blurred, overshoot, undershoot, etc. it can. In addition, since the artifact value quantitatively indicates the strength of the motion artifact, the user can confirm whether or not an overshoot or undershoot has occurred. In this way, by visualizing or quantifying the signal change on the difference image, the imaging operator can determine whether or not the degree of motion artifact on the difference image is at a level that allows clinical operation. It is possible to obtain a determination material for easier determination, and it is possible to quickly determine whether or not re-photographing is necessary.

  A display method in which the distribution of artifact values calculated two-dimensionally is overlaid on the difference image is also conceivable. For example, the artifact value can be qualitatively grasped by replacing the size of the artifact value with a color and making the display semi-transparent, so that the occurrence state of the artifact can be easily grasped.

  On the screen displaying the difference image and the motion artifact information in step S8, as shown in FIGS. 6 and 7, an OK button for instructing that shooting is OK (re-shooting is unnecessary). 541 and a re-shooting button 542 for instructing re-shooting are displayed. The photographer refers to the difference image and motion artifact information displayed on the display unit 54, and presses either the OK button 541 or the re-photograph button 542 with the operation unit 53.

  When the re-shooting button 542 is pressed by the operation unit 53 (step S9; re-shooting button), the process returns to step S2.

  When the OK button 541 is pressed by the operation unit 53 (step S9; OK button), it is determined whether or not the number of re-photographing for this examination is zero (step S10). When it is determined that the number of times of re-imaging for this examination is 0 (step S10; YES), the process proceeds to step S14.

  On the other hand, when it is determined that the number of re-photographing is not zero (one or more) (step S10; NO), the display unit 54 displays the difference image stored in the storage unit 52 in the current examination. A dialog for selecting a difference image to be transmitted to the server device 10 as an image obtained in the current examination is displayed (step S11). When a difference image is selected from the displayed dialog by the operation unit 53 (step S12; YES), a medical image related to the difference image that has not been selected (the difference image that has not been selected, and the radiation image that generated the difference image) ) And the motion artifact information generated based on the difference image are deleted from the storage unit 52 (step S13), and the process proceeds to step S14.

  In step S14, additional information (patient information, examination information, detailed image information, etc.) is added to the header part of the medical image obtained in the current examination based on the examination order information and imaging conditions specified in step S1. Is written and transmitted to the server apparatus 10 by the network communication unit 56, and the inspection ID of the current examination is associated with the motion artifact information and transmitted to the server apparatus 10 by the network communication unit 56 ( Step S14), the imaging control process A ends.

  In the server device 10, medical images (high energy image, low energy image, soft part image, bone part image) and motion artifact information transmitted from the imaging console 5 are stored in a database. In addition, the auxiliary information of each medical image is stored in the management table of the database in association with the examination ID, and the storage location of each medical image and motion artifact information is associated with the auxiliary information (for example, as the same record as the auxiliary information) ) Write to the management table. This makes it possible to search for medical image information and motion artifact information for each examination.

  When the diagnosis console 8 transmits the examination ID of the examination to be interpreted and instructed to read the medical image, the server device 10 reads the medical image from the database in response to a request from the diagnostic console 8. It transmits to the diagnostic console 8. In the diagnostic console 8, when the medical image from the server device 10 is acquired, the acquired medical image is displayed on the display unit. When the interpretation is completed and a diagnosis result or comment by the interpreter is input, the diagnosis console 8 transmits the input diagnosis result or comment information to the server device 10 and requests an update of the database. In response to a request from the diagnostic console 8, the server device 10 writes the diagnosis result and comment information for the medical image in the incidental information stored in association with the medical image, and updates the database.

  As described above, in the shooting console 5 in the first embodiment, the region where the motion artifact is generated on the difference image generated by the shooting and the difference process is displayed surrounded by the annotation. Can quickly identify areas where motion artifacts occur on the difference image to check whether the degree of motion artifacts is at a level that can be used clinically, and whether re-imaging is required It is possible to quickly determine whether or not. In addition, since the enlarged image of the area where the motion artifact is occurring and the information (signal value profile, profile value) indicating the strength of the motion artifact are displayed, the radiographer can determine the degree of motion artifact on the difference image clinically. It is possible to obtain a determination material for more easily determining whether or not the operation is possible, and it is possible to quickly determine whether or not re-shooting is necessary.

<Second Embodiment>
Next, a second embodiment of the present invention will be described.
A difference image (referred to as a past image) of a past examination for the same subject (the same part of the same patient) as the difference image generated by the examination this time, and how much motion artifact is interpreted in the image used for interpretation It is considered to be a criterion for judging whether or not it is acceptable. Therefore, in the second embodiment, an example in which the difference image generated by the current examination and the past image are displayed side by side on the imaging console 5 will be described.

  In the second embodiment, the storage unit 52 of the shooting console 5 stores a program for executing the shooting control process B shown in FIG. The control unit 51 functions as an acquisition unit by executing the shooting control process B in cooperation with a program stored in the storage unit 52.

  In addition to the functions described in the first embodiment, the server device 10 further reads out medical images and their supplementary information from the database in response to a request from the imaging console 5 and transmits them to the imaging console 5. Have

  Since the configuration of the other second embodiment is the same as that described with reference to FIGS. 1 and 2 in the first embodiment, the description will be referred to and the operation of the second embodiment will be described.

  FIG. 9 shows a flow of the shooting control process B executed in the shooting console 5. The imaging control process B in FIG. 9 is executed in cooperation with a program stored in the control unit 51 of the imaging console 5 and the storage unit 52 with the chest and abdomen of the human body as subjects.

  First, the processing of steps S21 to S26 is executed, two radiographic images (high energy image, low energy image) of the subject are acquired, and based on the acquired two radiographic images, a difference image (soft part image and Bone part image) is generated. Since the process of step S21-S26 is the same as that of step S1-S6 of FIG. 3, description is used.

  Next, in step S27, a past image (same part of the same patient) of the same subject as that of the difference image generated this time from the server device 10 and its accompanying information are acquired (step S27). That is, the patient information, the imaging region, and the like of the examination order information specified in step S21 are transmitted to the server device 10 by the network communication unit 56, and correspond to the past image having incidental information that matches the transmitted information and the past image. A request for acquisition of incidental information is made. The server device 10 searches the database for past images having supplementary information that matches the received information, and if there is a corresponding past image, reads the past image and supplementary information corresponding to the past image, and uses the Send to console 5. The past image stored in the server device 10 has been read before the current radiographic image is taken.

  Next, the difference image generated this time and the past image are displayed side by side on the display unit 54, and comment information included in the incidental information of the past image is displayed on the display unit 54 (step S28). Note that whether the soft part image or the bone part image is displayed as the difference image and the past image can be switched by the operation of the operation unit 53.

  FIG. 10 shows an example of a screen displayed on the display unit 54 in step S28. As shown in FIG. 10, in step S28, the difference image generated this time and its past image are displayed side by side, and comment information included in the incidental information of the past image is displayed. The comment information is comment information of the interpreter with respect to the past image. For example, it is preferable that the comment information includes comments regarding motion artifacts such as “a motion artifact is seen at the edge of the heart but there is no influence on the interpretation”. In order to show that the past image used for interpretation is acceptable for interpretation up to the same degree of motion artifact as the past image, the shooter compares the difference image generated this time with the past image, It is possible to quickly determine whether or not re-shooting is necessary.

  In step S27, if the past image does not exist in the server device 10 and cannot be acquired, the past image and its comment information are not displayed in step S28. When there are a plurality of past images, a switching button or the like may be displayed on the display unit 54, and the past image and comment information to be displayed may be switched in accordance with the operation of the switching button.

  Since the process of step S29-S34 is the same as that of step S9-S14 of FIG. 3, description is used. Note that since the motion artifact information is not generated in the second embodiment, the motion artifact information is not deleted in step S33. In step S34, motion artifact information is not transmitted.

  As described above, in the second embodiment, since the difference image generated this time and the past image of the same subject that has been interpreted are displayed side by side, the photographer can execute the difference image and the past image generated this time. , It is possible to quickly determine whether or not re-photographing is necessary. Further, by displaying the comment information at the time of interpretation of the past image, the photographer can determine the necessity of re-imaging while considering the situation at the time of interpretation of the past image.

<Third Embodiment>
Next, a third embodiment of the present invention will be described.
In the third embodiment, an example in which the first embodiment and the second embodiment are combined will be described.

  In the third embodiment, the storage unit 52 of the shooting console 5 stores a program for executing the shooting control process C shown in FIG. The control unit 51 functions as an acquisition unit and an analysis unit by executing the shooting control process C in cooperation with a program stored in the storage unit 52.

  Since the configuration of the other third embodiment is the same as that of the second embodiment, the description will be referred to and the operation of the third embodiment will be described.

  FIG. 11 shows a flow of the photographing control process C executed in the photographing console 5. The imaging control process C is executed in cooperation with the control unit 51 of the imaging console 5 and the program stored in the storage unit 52, with the subject's chest and abdomen as the target subjects.

  First, the processes of steps S41 to S47 are executed. That is, two radiation images (a high energy image and a low energy image) of the subject are acquired, and a difference image (a soft part image and a bone part image) is generated based on the two acquired radiation images. Then, among the difference images, motion artifact information on the difference image set as a motion artifact information generation target is generated. Since the process of step S41-S47 is the same as that of step S1-S7 of FIG. 3, description is used.

  Next, the past image of the same subject (the same part of the same patient) as the difference image generated this time, the accompanying information, and the motion artifact information thereof are acquired from the server device 10 (step S48). Since the process of step S48 is the same as step S27 of FIG. 9 except that motion artifact information is added to the information to be acquired, the description is incorporated. In addition, when there is no motion artifact information corresponding to the past image, the above-described analysis process may be executed on the acquired past image to generate motion artifact information.

Next, the difference image generated this time and the past image are arranged on the display unit 54 and displayed in a state where the motion artifact information is displayed, respectively, and the comment information included in the incidental information of the past image is displayed on the display unit 54. (Step S49).
For example, the difference image generated this time in the same display mode as shown in FIGS. 6 to 7 and the past image in which motion artifact information is displayed are displayed side by side as shown in FIG. Comment information included in the incidental information of the past image is displayed.

  Since the process of step S50-step S55 is the same as that of step S9-S14 of FIG. 3, description is used.

  As described above, the difference image generated this time and the past image of the same subject are displayed side by side on the display unit 54 and the motion artifact information is displayed. By comparing with past images that have been interpreted, it is possible to quickly determine whether or not re-shooting is necessary. Further, by comparing the motion artifact information of the difference image generated this time with the motion artifact information of the past image, it is possible to more easily and quickly determine whether or not re-shooting is necessary.

  The first to third embodiments of the present invention have been described above. However, the description in the above embodiment is a preferred example of the medical image photographing system according to the present invention, and the present invention is not limited to this.

  For example, in the above description, an example in which a hard disk, a semiconductor nonvolatile memory, or the like is used as a computer-readable medium of the program according to the present invention is 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 program data according to the present invention via a communication line.

  In addition, the detailed configuration and detailed operation of each device constituting the medical image photographing system can be changed as appropriate without departing from the spirit of the invention.

100 Medical Image Shooting System 1 Bucky Device 2 Bucky Device 3 Radiation Source 5 Imaging Console 51 Control Unit 52 Storage Unit 53 Operation Unit 54 Display Unit 55 Communication I / F
56 Network communication section 57 Bus 6 Console 7 HIS / RIS
8 Diagnosis console 9 FPD
10 Server device

Claims (15)

In a medical image processing apparatus that generates a difference image by performing a difference process on a plurality of radiation images obtained by irradiating radiation of two different types of energy to the same subject at different timings,
Analyzing the difference image or the plurality of radiation images to generate information on motion artifacts on the difference image resulting from the movement of the structure in the subject;
Display means for displaying information on the difference image and motion artifacts on the difference image;
A medical image processing apparatus comprising: The analysis means analyzes the difference image to identify a motion artifact occurrence region on the difference image caused by the movement of the structure in the subject and generate information indicating the motion artifact occurrence region And
The medical image processing apparatus according to claim 1, wherein the display unit displays information indicating a motion artifact occurrence region on the difference image. The analysis means calculates a movement amount of the structure in the subject between the plurality of radiation images by analyzing the plurality of radiation images, and based on the calculated movement amount, Generating information indicating the generation area of the motion artifact on the difference image due to the movement of the structure of
The medical image processing apparatus according to claim 1, wherein the display unit displays information indicating a motion artifact occurrence region on the difference image.   The medical image processing apparatus according to any one of claims 1 to 3, further comprising a setting unit configured to set an analysis target region to be analyzed in the difference image or the plurality of radiation images. The analysis unit generates information indicating the strength of motion artifacts on the difference image due to the movement of the structure in the subject by analyzing the difference image,
The medical image processing apparatus according to any one of claims 1 to 4, wherein the display unit displays information indicating the difference image and a strength of a motion artifact on the difference image. With operating means,
The medical image according to claim 5, wherein the display means enlarges and displays the area designated by the operation means on the difference image, and displays information indicating the strength of the motion artifact in the enlarged display area. Processing equipment.   The information indicating the strength of the motion artifact is obtained by normalizing the pixel signal value profile in the designated area of the difference image and / or the pixel signal value of the radiation image before the difference at the same position as the profile. The medical image processing apparatus according to claim 5, wherein the medical image processing apparatus is a difference value with respect to the profile and a value equal to or greater than a predetermined threshold. An acquisition unit that acquires the past difference image from a storage unit that stores the past difference image of the subject generated before the difference image;
The medical image processing apparatus according to claim 1, wherein the display unit displays the difference image and the past difference image side by side.   9. The medical image processing apparatus according to claim 8, wherein the display unit further displays information on motion artifacts on the past difference image generated by analyzing the past difference image of the subject by the analysis unit. .   The medical image processing apparatus according to claim 1, further comprising an input unit configured to input an instruction for re-imaging the plurality of radiation images. In a medical image processing apparatus that generates a difference image by performing a difference process on a plurality of radiation images obtained by irradiating radiation of two different types of energy to the same subject at different timings,
An acquisition means for acquiring the past difference image from a storage means for storing a past difference image of the subject generated before the difference image;
Display means for displaying the difference image and the past difference image;
An input means for inputting an instruction for re-imaging the plurality of radiation images;
A medical image processing apparatus comprising: The past difference image is associated with information on motion artifacts of the past difference image,
The acquisition means acquires information on motion artifacts of the past difference image together with the past difference image,
The medical image processing apparatus according to claim 8, wherein the display unit further displays information on motion artifacts of the past difference image.   The medical image processing apparatus according to claim 12, wherein the information related to motion artifacts in the past difference image includes a comment related to motion artifacts in the past difference image by a reader of the past difference image. A computer used for a medical image processing apparatus that generates a differential image by performing differential processing on a plurality of radiographic images acquired by irradiating radiation of two different types of energy to the same subject at different timings,
Analyzing means for generating information on motion artifacts on the difference image resulting from the movement of the structure in the subject by analyzing the difference image or the plurality of radiation images;
Display means for displaying information on the difference image and motion artifact on the difference image;
Program to function as. A computer used for a medical image processing apparatus that generates a differential image by performing differential processing on a plurality of radiographic images acquired by irradiating radiation of two different types of energy to the same subject at different timings,
An acquisition means for acquiring the past difference image from a storage means for storing a past difference image of the subject generated before the difference image;
Display means for displaying the difference image and the past difference image;
Input means for inputting an instruction for re-imaging the plurality of radiation images;
Program to function as.