JP6943616B2 - X-ray CT equipment, medical information processing equipment and medical information processing program - Google Patents

Description

Embodiments of the present invention relate to an X-ray CT apparatus, a medical information processing apparatus, and a medical information processing program.

Conventionally, it is known that the causes of ischemic diseases of organs are roughly classified into blood circulation disorders and dysfunctions of organs themselves. For example, stenosis, which is an example of coronary artery blood circulation disorder, is a serious lesion leading to ischemic heart disease. In such ischemic heart disease, whether drug treatment should be performed, stent treatment, etc. should be performed. You need to judge. In recent years, as a diagnosis for evaluating hematogenous ischemia of coronary arteries, a method of measuring myocardial flow reserve (FFR) using a pressure wire in coronary angiography (CAG) using a catheter has been used. It is being recommended.

On the other hand, for example, hematogenous ischemia of the coronary artery using a medical image of the heart collected by a medical image diagnostic device such as an X-ray CT (Computed Tomography) device, an MRI (Magnetic Resonance Imaging) device, or an ultrasonic diagnostic device. A method of performing evaluation non-invasively is also known. In recent years, hematogenous ischemia is evaluated by such various methods, and treatment is performed according to the evaluation.

Japanese Unexamined Patent Publication No. 2014-108208 Japanese Unexamined Patent Publication No. 2014-08735 JP-A-2015-110155

An object to be solved by the present invention is to provide an X-ray CT apparatus, a medical information processing apparatus, and a medical information processing program capable of easily selecting appropriate data.

The X-ray CT apparatus according to the embodiment includes a collecting unit, a selection unit, and an analysis unit. The collecting unit collects image data relating to multiple time phases, including at least a part of the coronary arteries of the heart. The selection unit acquires an image index related to the plurality of the image data, and based on the image index in each image data, is a combination of the image data having a time interval larger than a predetermined time interval among the plurality of the image data. Extract a set of image data from the data. The analysis unit performs fluid analysis on the coronary arteries based on the set of the extracted image data, and obtains fluid parameters on the coronary arteries.

FIG. 1 is a diagram showing an example of a configuration of a medical information processing system according to the first embodiment. FIG. 2 is a diagram showing an example of the configuration of the X-ray CT apparatus according to the first embodiment. FIG. 3 is a diagram for explaining an example of processing by the analysis function according to the first embodiment. FIG. 4 is a diagram for explaining the selection of the time phase by the selection function according to the first embodiment. FIG. 5 is a diagram showing an example of a change in image quality of each core phase according to the first embodiment. FIG. 6 is a diagram for explaining an example of the selection process by the selection function according to the first embodiment. FIG. 7 is a diagram for explaining an example of the search process of the optimum core phase by the selection function according to the first embodiment. FIG. 8 is a diagram for explaining an example of threshold processing by the selection function according to the first embodiment. FIG. 9 is a diagram for explaining an example of the selection process by the selection function according to the first embodiment. FIG. 10 is a flowchart showing a processing procedure by the X-ray CT apparatus according to the first embodiment. FIG. 11 is a diagram for explaining an example of selection processing by the selection function according to the second embodiment. FIG. 12 is a flowchart showing a processing procedure by the X-ray CT apparatus according to the second embodiment. FIG. 13 is a diagram for explaining the selection of the time phase by the selection function according to the third embodiment. FIG. 14 is a flowchart showing a processing procedure by the X-ray CT apparatus according to the third embodiment. FIG. 15 is a diagram showing an example of the configuration of the medical information processing device according to the third embodiment.

Hereinafter, embodiments of the X-ray CT apparatus, the medical information processing apparatus, and the medical information processing program according to the present application will be described in detail with reference to the accompanying drawings. The X-ray CT apparatus, the medical information processing apparatus, and the medical information processing program according to the present application are not limited to the embodiments shown below.

(First Embodiment)
First, the first embodiment will be described. In the first embodiment, an example in which the technique disclosed in the present application is applied to an X-ray CT apparatus will be described. Hereinafter, a medical information processing system including an X-ray CT apparatus will be described as an example. Further, in the following, as an example, an example in which a blood vessel of the heart is analyzed will be described.

FIG. 1 is a diagram showing an example of a configuration of a medical information processing system according to the first embodiment. As shown in FIG. 1, the medical information processing system according to the first embodiment includes an X-ray CT (Computed Tomography) device 100, an image storage device 200, and a medical information processing device 300.

For example, as shown in FIG. 1, the X-ray CT apparatus 100 according to the first embodiment is connected to the image storage apparatus 200 and the medical information processing apparatus 300 via the network 400. The medical information processing system may be further connected to other medical image diagnostic devices such as an MRI device, an ultrasonic diagnostic device, and a PET (Positron Emission Tomography) device via the network 400.

The image storage device 200 stores image data collected by various medical image diagnostic devices. For example, the image storage device 200 is realized by a computer device such as a server device. In the present embodiment, the image storage device 200 acquires CT image data (volume data) from the X-ray CT device 100 via the network 400, and stores the acquired CT image data inside or outside the device. To memorize.

The medical information processing device 300 acquires image data from various medical image diagnostic devices via the network 400, and processes the acquired image data. For example, the medical information processing apparatus 300 is realized by a computer device such as a workstation. In the present embodiment, the medical information processing apparatus 300 acquires CT image data from the X-ray CT apparatus 100 or the image storage apparatus 200 via the network 400, and performs various image processing on the acquired CT image data. Then, the medical information processing apparatus 300 displays the CT image data before or after performing the image processing on a display or the like.

The X-ray CT apparatus 100 collects CT image data of a subject. Specifically, the X-ray CT apparatus 100 swirls the X-ray tube and the X-ray detector around the subject, detects the X-rays that have passed through the subject, and collects projection data. Then, the X-ray CT apparatus 100 generates time-series three-dimensional CT image data based on the collected projection data. FIG. 2 is a diagram showing an example of the configuration of the X-ray CT apparatus 100 according to the first embodiment. As shown in FIG. 2, the X-ray CT apparatus 100 according to the first embodiment includes a gantry 10, a sleeper apparatus 20, and a console 30.

The gantry 10 is a device that irradiates the subject P (patient) with X-rays, detects the X-rays transmitted through the subject P, and outputs the X-rays to the console 30. The X-ray irradiation control circuit 11 and the X-ray generator are generated. It has a device 12, a detector 13, a data acquisition circuit (DAS: Data Acquisition System) 14, a rotating frame 15, and a gantry drive circuit 16.

The rotating frame 15 supports the X-ray generator 12 and the detector 13 so as to face each other with the subject P in between, and rotates at high speed in a circular orbit centered on the subject P by a gantry drive circuit 16 described later. It is a circular frame.

The X-ray irradiation control circuit 11 is a device that supplies a high voltage to the X-ray tube 12a as a high voltage generating unit, and the X-ray tube 12a uses the high voltage supplied from the X-ray irradiation control circuit 11 to X. Generate a line. The X-ray irradiation control circuit 11 adjusts the X-ray dose to be irradiated to the subject P by adjusting the tube voltage and the tube current supplied to the X-ray tube 12a under the control of the scan control circuit 33 described later. ..

Further, the X-ray irradiation control circuit 11 switches the wedge 12b. Further, the X-ray irradiation control circuit 11 adjusts the X-ray irradiation range (fan angle and cone angle) by adjusting the opening degree of the collimator 12c. In this embodiment, the operator may manually switch between a plurality of types of wedges.

The X-ray generator 12 is a device that generates X-rays and irradiates the subject P with the generated X-rays, and has an X-ray tube 12a, a wedge 12b, and a collimator 12c.

The X-ray tube 12a is a vacuum tube that irradiates the subject P with an X-ray beam by a high voltage supplied by a high voltage generator (not shown), and the X-ray beam is sent to the subject P as the rotating frame 15 rotates. Irradiate against. The X-ray tube 12a generates an X-ray beam that spreads with a fan angle and a cone angle. For example, under the control of the X-ray irradiation control circuit 11, the X-ray tube 12a is continuously exposed to X-rays all around the subject P for full reconstruction, or half-reconstructable for half-reconstruction. It is possible to continuously expose X-rays within the range (180 degrees + fan angle). Further, under the control of the X-ray irradiation control circuit 11, the X-ray tube 12a can intermittently emit X-rays (pulse X-rays) at a preset position (tube position). The X-ray irradiation control circuit 11 can also modulate the intensity of X-rays exposed from the X-ray tube 12a. For example, the X-ray irradiation control circuit 11 increases the intensity of X-rays emitted from the X-ray tube 12a at a specific tube position, and exposes the X-ray tube 12a to a range other than the specific tube position. Decreases the intensity of the emitted X-rays.

The wedge 12b is an X-ray filter for adjusting the X-ray dose of X-rays exposed from the X-ray tube 12a. Specifically, the wedge 12b transmits the X-rays exposed from the X-ray tube 12a so that the X-rays radiated from the X-ray tube 12a to the subject P have a predetermined distribution. It is a filter that attenuates. For example, the wedge 12b is a filter made of aluminum so as to have a predetermined target angle and a predetermined thickness. The wedge is also called a wedge filter or a bow-tie filter.

The collimator 12c is a slit for narrowing down the X-ray irradiation range in which the X-ray dose is adjusted by the wedge 12b under the control of the X-ray irradiation control circuit 11 described later.

The gantry drive circuit 16 rotates the rotating frame 15 to rotate the X-ray generator 12 and the detector 13 on a circular orbit centered on the subject P.

The detector 13 is a two-dimensional array type detector (surface detector) that detects X-rays that have passed through the subject P, and the detection element sequence formed by arranging X-ray detection elements for a plurality of channels is the subject P. A plurality of rows are arranged along the body axis direction (Z-axis direction shown in FIG. 2). Specifically, the detector 13 in the first embodiment has X-ray detection elements arranged in multiple rows such as 320 rows along the body axis direction of the subject P, for example, the lungs of the subject P. It is possible to detect X-rays that have passed through the subject P over a wide range, such as in the range including the heart and the heart.

The data acquisition circuit 14 is a DAS and collects projection data from the X-ray detection data detected by the detector 13. For example, the data acquisition circuit 14 generates projection data by performing amplification processing, A / D conversion processing, sensitivity correction processing between channels, and the like on the X-ray intensity distribution data detected by the detector 13. The projected projection data is transmitted to the console 30 described later. For example, when X-rays are continuously exposed from the X-ray tube 12a during the rotation of the rotating frame 15, the data acquisition circuit 14 collects the projection data group for the entire circumference (360 degrees). Further, the data acquisition circuit 14 associates the tube position with each of the collected projection data and transmits the data to the console 30 described later. The tube position is information indicating the projection direction of the projection data. The sensitivity correction processing between channels may be performed by the preprocessing circuit 34, which will be described later.

The sleeper device 20 is a device on which the subject P is placed, and has a sleeper drive device 21 and a top plate 22 as shown in FIG. The sleeper drive device 21 moves the top plate 22 in the Z-axis direction to move the subject P into the rotating frame 15. The top plate 22 is a plate on which the subject P is placed.

The gantry 10 executes, for example, a helical scan in which the rotating frame 15 is rotated while the top plate 22 is moved to spirally scan the subject P. Alternatively, the gantry 10 executes a conventional scan in which the rotating frame 15 is rotated while the position of the subject P is fixed after the top plate 22 is moved to scan the subject P in a circular orbit. Alternatively, the gantry 10 executes a step-and-shoot method in which the position of the top plate 22 is moved at regular intervals to perform a conventional scan in a plurality of scan areas.

The console 30 is a device that accepts the operation of the X-ray CT device 100 by the operator and reconstructs the CT image data (volume data) using the projection data collected by the gantry 10. As shown in FIG. 2, the console 30 includes an input circuit 31, a display 32, a scan control circuit 33, a preprocessing circuit 34, a storage circuit 35, an image reconstruction circuit 36, and a processing circuit 37. ..

The input circuit 31 has a mouse, keyboard, trackball, switch, button, joystick, etc. used by the operator of the X-ray CT device 100 to input various instructions and various settings, and information on the instructions and settings received from the operator. Is transferred to the processing circuit 37. For example, the input circuit 31 receives from the operator the imaging conditions for the CT image data, the reconstruction conditions for reconstructing the CT image data, the image processing conditions for the CT image data, and the like. Further, the input circuit 31 accepts an operation for selecting a test for the subject P. Further, the input circuit 31 accepts a designation operation for designating a portion on the image.

The display 32 is a monitor referred to by the operator, and under the control of the processing circuit 37, the image data generated from the CT image data is displayed to the operator, and various types are displayed by the operator via the input circuit 31. It displays a GUI (Graphical User Interface) for receiving instructions and various settings. In addition, the display 32 displays a plan screen for a scan plan, a screen during scanning, and the like.

The scan control circuit 33 controls the operations of the X-ray irradiation control circuit 11, the gantry drive circuit 16, the data acquisition circuit 14, and the sleeper drive device 21 under the control of the processing circuit 37 to control the operation of the projection data on the gantry 10. Control the collection process. Specifically, the scan control circuit 33 controls the collection process of projection data in the imaging for collecting the positioning image (scano image) and the main imaging (scan) for collecting the image used for diagnosis.

The preprocessing circuit 34 performs logarithmic conversion processing and correction processing such as offset correction, sensitivity correction, and beam hardening correction on the projection data generated by the data acquisition circuit 14, and obtains the corrected projection data. Generate. Specifically, the preprocessing circuit 34 generates corrected projection data for each of the projection data of the positioning image generated by the data acquisition circuit 14 and the projection data collected by the main shooting, and the storage circuit 35. Store in.

The storage circuit 35 stores the projection data generated by the preprocessing circuit 34. Specifically, the storage circuit 35 stores the projection data of the positioning image generated by the preprocessing circuit 34 and the projection data for diagnosis collected by the main imaging. Further, the storage circuit 35 stores CT image data and the like reconstructed by the image reconstruction circuit 36 described later. Further, the storage circuit 35 appropriately stores the processing result by the processing circuit 37 described later.

The image reconstruction circuit 36 reconstructs CT image data using the projection data stored in the storage circuit 35. Specifically, the image reconstruction circuit 36 reconstructs CT image data from the projection data of the positioning image and the projection data of the image used for diagnosis. Here, there are various reconstruction methods, and examples thereof include back projection processing. Further, as the back projection process, for example, a back projection process by the FBP (Filtered Back Projection) method can be mentioned. Alternatively, the image reconstruction circuit 36 can reconstruct the CT image data using the successive approximation method.

Further, the image reconstruction circuit 36 generates image data by performing various image processing on the CT image data. Then, the image reconstruction circuit 36 stores the reconstructed CT image data and the image data generated by various image processes in the storage circuit 35.

The processing circuit 37 controls the operation of the gantry 10, the sleeper device 20, and the console 30 to control the entire X-ray CT device 100. Specifically, the processing circuit 37 controls the CT scan performed on the gantry 10 by controlling the scan control circuit 33. Further, the processing circuit 37 controls the image reconstruction processing and the image generation processing in the console 30 by controlling the image reconstruction circuit 36. Further, the processing circuit 37 controls the display 32 to display various image data stored in the storage circuit 35.

Under such a configuration, the X-ray CT apparatus 100 according to the present embodiment makes it possible to easily select appropriate data. Specifically, the X-ray CT apparatus 100 simply uses appropriate data as data for calculating an index value related to blood flow by fluid analysis using a medical image including blood vessels (for example, three-dimensional CT image data). Allows you to choose. For example, the X-ray CT apparatus 100 selects appropriate time-phase CT image data as data to be used for fluid analysis from a plurality of time-phase CT image data collected over time.

Here, examples of the index value related to blood flow include a myocardial blood flow reserve ratio (FFR: Fractional Flow Reserve), a mechanical index in a blood vessel, an index related to blood flow rate, and the like. FFR is the ratio of the pressure in the proximal part of the blood vessel near the heart to the pressure in the distal part far from the heart, for example, "FFR = Pd (distal pressure) / Pa (proximal pressure). ) ”. For example, when a blood vessel has a stenosis (a site to be treated), the pressure in the distal portion decreases due to the stenosis, so that the FFR value decreases. The fluid analysis is used to determine the necessity of treatment by calculating such an FFR value or the like. Examples of the mechanical index in the blood vessel include pressure, vector, and shear stress. In addition, examples of the index related to the blood flow rate include the flow rate and the flow velocity.

Hereinafter, in the first embodiment, a case where appropriate CT image data is selected in fluid analysis for a coronary artery will be described as an example. As shown in FIG. 2, the processing circuit 37 according to the present embodiment executes the control function 37a, the analysis function 37b, the selection function 37c, the acquisition function 37d, and the presentation function 37e. Here, for example, each processing function executed by the control function 37a, the analysis function 37b, the selection function 37c, the acquisition function 37d, and the presentation function 37e, which are the components of the processing circuit 37 shown in FIG. 2, is a program that can be executed by a computer. Is recorded in the storage circuit 35 in the form of. The processing circuit 37 is a processor that realizes a function corresponding to each program by reading each program from the storage circuit 35 and executing the program. In other words, the processing circuit 37 in the state where each program is read has each function shown in the processing circuit 37 of FIG. The analysis function 37b described in the present embodiment is an example of the analysis unit described in the claims. Further, the selection function 37c is an example of the selection unit described in the claims. The acquisition function 37d is an example of an acquisition unit. Further, the presentation function 37e is an example of the presentation unit described in the claims.

The control function 37a executes overall control of the X-ray CT apparatus 100. For example, the control function 37a executes the above-mentioned control related to scanning, reconstruction of CT image data, control related to generation of various images from CT image data, display control of various generated images, and the like.

The analysis function 37b executes the fluid analysis based on the CT image data. Specifically, the analysis function 37b extracts time-series blood vessel shape data representing the shape of blood vessels from three-dimensional CT image data. For example, the analysis function 37b reads out the CT image data of the plurality of time phases collected over time from the storage circuit 35, and performs image processing on the read CT image data of the plurality of time phases to perform time-series blood vessels. Extract shape data.

Here, the analysis function 37b sets a target region for calculating an index value in the blood vessel region included in the CT image data. Specifically, the analysis function 37b sets the target region in the blood vessel region by an instruction or image processing by the operator via the input circuit 31. Then, the analysis function 37b uses, for example, the core wire (coordinate information of the core wire) of the blood vessel, the cross-sectional area of the blood vessel and the lumen in the cross section perpendicular to the core wire, and the cross section perpendicular to the core wire as the blood vessel shape data of the set target region. The distance from the core wire to the inner wall and the distance from the core wire to the outer wall in the columnar direction of the above are extracted from the CT image data. The analysis function 37b can extract various other blood vessel shape data depending on the analysis method.

Further, the analysis function 37b sets the analysis conditions for fluid analysis. Specifically, the analysis function 37b sets the physical characteristic value of blood, the condition of iterative calculation, the initial value of analysis, and the like as the analysis condition. For example, the analysis function 37b sets the viscosity, density, and the like of blood as physical property values of blood. Further, the analysis function 37b sets the maximum number of iterations in the iterative calculation, the relaxation coefficient, the allowable value of the residual, and the like as the conditions for the iterative calculation. Further, the analysis function 37b sets the flow rate, pressure, fluid resistance, initial value of the pressure boundary, and the like as the initial value of the analysis. The various values used by the analysis function 37b may be incorporated in the system in advance, or may be defined interactively by the operator.

In addition, the analysis function 37b sets a treatment target site in the blood vessel in the image data. Specifically, the analysis function 37b manually or automatically sets the treatment target site in the blood vessel. For example, the analysis function 37b sets a range received via the input circuit 31 as a treatment target site. In such a case, the input circuit 31 accepts a range for changing the analysis condition (treatment target site), and the range in which the analysis function 37b is accepted is set as the treatment target site. In addition, the analysis function 37b automatically sets the treatment target site based on the shape in the target region. For example, the analysis function 37b extracts a stenosis portion based on the shape in the target region, and sets a stenosis portion having a certain degree of stenosis or more as a treatment target site among the extracted stenosis portions. Any method can be used to extract the stenotic portion.

Then, the analysis function 37b calculates an index value related to blood flow in the blood vessel by fluid analysis using image data including the blood vessel. Specifically, the analysis function 37b executes fluid analysis using the blood vessel shape data and the analysis conditions, and calculates an index value (fluid parameter) related to blood flow in the target region of the blood vessel. For example, the analysis function 37b is based on blood vessel shape data such as the contour of the blood vessel lumen and outer wall, the cross-sectional area of the blood vessel, and the core wire, and setting conditions such as blood physical properties, repeated calculation conditions, and initial analysis values. , Calculate index values such as pressure, blood flow rate, blood flow velocity, vector and shear stress for each predetermined position of blood vessel. Then, the analysis function 37b further calculates an index value such as FFR from the calculated index value.

FIG. 3 is a diagram for explaining an example of processing by the analysis function 37b according to the first embodiment. As shown in FIG. 3, for example, the analysis function 37b extracts blood vessel shape data including core line coordinates and cross-sectional information for LAD, which is a target region, from three-dimensional CT image data including aorta and coronary arteries. Further, the analysis function 37b sets the analysis conditions for the analysis of the extracted LAD. Then, the analysis function 37b performs a fluid analysis using the extracted blood vessel shape data of the LAD and the set conditions, so that, for example, from the boundary of the inlet to the boundary of the exit of the target region LAD, a predetermined value along the core line is performed. Index values such as pressure, blood flow rate, blood flow velocity, vector and shear stress are calculated for each position. That is, the analysis function 37b calculates the distribution of pressure, blood flow rate, blood flow velocity, vector, shear stress, and the like for the target region. Then, the analysis function 37b calculates the FFR of each position in the target region based on, for example, the calculated pressure distribution.

As described above, the analysis function 37b extracts blood vessel shape data from the CT image data of the plurality of time phases collected over time, and fluid analysis using the extracted blood vessel shape data of the plurality of time phases and analysis conditions. By performing the above, the index value related to blood flow is calculated. Here, in order to obtain a highly accurate analysis result when performing such a fluid analysis of the coronary artery, it is a plurality of time phases that include as much as possible a change in the shape of the coronary artery (for example, a change in the cross-sectional area). Moreover, it is desirable that the CT image data of each time phase is as sharp as possible. That is, the time-series blood vessel shape data is based on pulsation while including as much as possible a series of changes from the time phase in which blood flows in and the area of the coronary artery is maximized to the time phase in which blood flows out and the area is minimized. It is desirable to use CT image data of the time phase with little image movement (blurring). Therefore, in the first embodiment, the selection function 37c selects the time phase corresponding to the above-mentioned CT image data from each time phase of the CT image data collected over time.

The selection function 37c selects a time phase in which the image is less blurred due to pulsation while including a change in the shape of the coronary artery from the CT image data of a plurality of time phases collected over time. Specifically, the selection function 37c is a time phase in which the movement associated with the pulsation is relatively small from each time phase corresponding to a plurality of CT image data, and the time interval between the time phases is large. Select multiple time phases. More specifically, the selection function 37c extracts a range of the time phase in which the movement associated with the pulsation is relatively small in each time phase corresponding to the plurality of CT image data, and the time phase included in the extracted range. Based on the evaluation of the movement associated with the beat in the image data corresponding to, the movement associated with the beat is relatively small among the time phases included in the range, and the time interval between the time phases is large. Select multiple time phases so that

Here, the selection function 37c evaluates the movement associated with the heartbeat based on the image index in each CT image data, and is a time phase in which the movement associated with the heartbeat is relatively small, and the time between the time phases. Select multiple time phases so that the intervals are large. That is, the selection function 37c acquires an image index for each CT image data. Then, the selection function 37c selects a set of CT image data from a combination of CT image data having a time interval larger than a predetermined time interval among a plurality of CT image data based on the image index in each image data. Extract. For example, the selection function 37c extracts a set of CT image data in which the image quality index of each CT image data is equal to or higher than a predetermined threshold value from the combination of CT image data. Here, the image quality index is an example of an image index. Hereinafter, an example of selection of a plurality of time phases (selection of a set of CT image data) based on an image quality index will be described.

FIG. 4 is a diagram for explaining the selection of the time phase by the selection function 37c according to the first embodiment. In FIG. 4, the heartbeat is shown in the upper row, the movement of the heart is shown in the middle row, and the area of the coronary artery is shown in the lower row. Further, in FIG. 4, the lateral direction indicates time, and the heartbeat, the movement of the heart, and the time change of the area of the coronary artery are shown in association with each other. For example, the selection function 37c selects a core phase included in the range of 70% to 99% of the core phase. Here, the cardiac phase of 70% to 99% is a time phase in which there is not much movement of the heart and the change in the area of the coronary artery is large, as shown in FIG. The heart moves by contraction and expansion, and as shown in the middle part of FIG. 4, the movement stabilizes in the latter half of the diastole (heart phase 70% to 99%). The selection function 37c selects the time phase in which the movement associated with the pulsation is relatively small by selecting the heart phase included in the heart phase of 70% to 99% in which the movement is stable. The cardiac phase of 70% to 99% corresponds to the Wave Free Period. The Wave Free Period is a mid-diastolic phase that is unaffected by the ejection pressure wave that descends the coronary artery from the pulse and the reflex pressure that is formed by the left ventricular pressure and propagates retrogradely through the coronary artery.

Further, as shown in the lower part of FIG. 4, the area of the coronary artery is maximum at around 70% of the cardiac phase and minimum at around 99%. This is because blood begins to flow into the coronary arteries at around 70% of the cardiac phase, and then blood flows out as it progresses to 99%. The selection function 37c selects a plurality of time phases so that the time interval between the time phases is as large as possible in the range of 70% to 99% of the cardiac phases so as to include the change in the area of the coronary arteries as much as possible.

Here, in the cardiac phase of 70 to 99%, the movement of the heart is not so much and is stable, but the image quality of the actually collected CT image data fluctuates. Further, in the vicinity of the cardiac phase of 99%, it is affected by the next contraction of the heart, and blurring may occur. FIG. 5 is a diagram showing an example of a change in image quality of each core phase according to the first embodiment. In FIG. 5, the horizontal axis represents time and the vertical axis represents image quality. For example, as shown in FIG. 5, the image quality of the CT image data gradually improves toward the vicinity of the cardiac phase of 70%, and changes while fluctuating in the vicinity of a certain image quality. Then, the image quality of the CT image data drops sharply near the cardiac phase of 99%. As described above, the image quality of the CT image data is not constant even within the range of the cardiac phase of 70% to 99%, and changes greatly.

Therefore, the selection function 37c evaluates the movement of each CT image data corresponding to the heart phase of 70% to 99%, in which the movement of the heart phase is relatively small, of the heart phase of 70% to 99%. Select a cardiac phase from% that has a smaller movement associated with the beat. Here, the selection function 37c selects the heart phase from 70% to 99% of the heart phases so that the movement associated with the beat is smaller and the time interval is larger. Hereinafter, the processing of the selection function 37c will be described by taking as an example the case where four core phases are selected from the core phases of 70% to 99%.

In such a case, the selection function 37c selects a plurality of core phases so that the time intervals between the adjacent core phases are large in the plurality of time phases and they are close to each other. For example, when the selection function 37c selects four heart phases from 70% to 99% of the heart phases, the CT image data in each heart phase moves less with the beat and the adjacent heart phases are smaller. Four core phases are selected so that the time intervals between them are close to equal intervals. This is because the fluid analysis of the coronary arteries analyzes how the area of the coronary arteries fluctuates (the tendency of fluctuation) as described above, so that the cardiac phases of the CT image data applied to the fluid analysis are as evenly spaced as possible. Is desirable.

Hereinafter, an example of the selection process of the four core phases by the selection function 37c will be described. For example, the selection function 37c divides a range (Wave Free Period) into a plurality of subranges, and for each subrange, a time phase in which the movement associated with pulsation is relatively small from among the time phases included in the subrange. Select each. That is, the selection function 37c divides 70% to 99% of the core phases into four regions, and selects one core phase from each of the divided regions. FIG. 6 is a diagram for explaining an example of the selection process by the selection function 37c according to the first embodiment. For example, the selection function 37c shifts the cardiac phase from 70% to 99% into four regions of "70 to 76%", "77% to 83%", "84% to 91%", and "92 to 99%". Divide and search and select the optimum phase in each area. Then, the CT image data of the four optimum core phases is reconstructed from the core phase data corresponding to the four core phases selected from each region by the selection function 37c.

The search for the optimum core phase in each region shown in FIG. 6 is, for example, to search for a heart phase in which the movement associated with the beat is smaller. For example, the selection function 37c evaluates the degree of blur (sharpness) in the image using the cardiac phase data of every 1% in the projection data of the cardiac phase of 70% to 90% collected in the electrocardiogram synchronization, and evaluates the degree of blur (sharpness) in the image. The core phase data with the least blur is selected as the core phase data to be reconstructed.

FIG. 7 is a diagram for explaining an example of the search process of the optimum core phase by the selection function 37c according to the first embodiment. FIG. 7 shows a case where the optimum core phase of “70 to 76%” is searched. For example, the selection function 37c extracts one slice of synogram including a coronary artery from the projection data of a plurality of heartbeats. Then, as shown in FIG. 7, the selection function 37c has "70%" heart phase data, "71%" heart phase data, "72%" heart phase data, and "73%" from each extracted synogram. By extracting and reconstructing the cardiac phase data of "74%", the cardiac phase data of "75%", and the cardiac phase data of "76%", the coronary arteries in each cardiac phase are included. Generate one slice of image.

Then, the selection function 37c calculates the SD value for each generated image of the core phase, extracts an image with less blur (high sharpness) based on the calculated SD value, and the core phase of the extracted image. Is selected as the optimum core phase. For example, as shown in FIG. 7, the selection function 37c sets the cardiac phase “74%” of an image having a narrow hem width to “70 to 76%” in the distribution of the signal intensity (pixel value) for each pixel of each image. Select as the optimum core phase in the region of. The SD value described above is a standard deviation of the signal strength for each pixel included in the image, and is an index value indicating noise characteristics.

The selection function 37c also executes the above-mentioned selection process for the three regions of "77% to 83%", "84% to 91%", and "92 to 99%", and the optimum center from each region. Select the phase. Here, if the optimum core phase is selected from each region as described above, the time interval of the optimum core phase selected in each region may be shortened. For example, when the optimum core phase in the region of "70 to 76%" is selected as "74%" and the optimum core phase in the region of "77% to 83%" is selected as "77%", the time interval is "77%". That's 3%. As described above, in the CT image data used for fluid analysis, it is desirable that the time intervals between the heart phases are large and even.

Therefore, the selection function 37c selects a plurality of core phases so that the time interval between the core phases is equal to or greater than a predetermined threshold value in the core phases included in the range. FIG. 8 is a diagram for explaining an example of threshold processing by the selection function 37c according to the first embodiment. For example, the selection function 37c executes the selection process using "5%" as the threshold value of the time interval as shown in FIG. As an example, the selection function 37c has an interval of "79%" from "74%" to "5%" or more when the optimum core phase in the region of "70 to 76%" is selected as "74%". Is used as the lower end to search for the optimum core phase in the region of "77 to 83%". That is, the selection function 37c searches for the optimum core phase in the region of "79 to 83%". The threshold value of the time interval is arbitrarily set.

As described above, when the selection function 37c selects the optimum central phase from the four regions of "70 to 76%", "77% to 83%", "84% to 91%", and "92 to 99%". , The acquisition function 37d acquires the cardiac phase data corresponding to the plurality of time phases selected by the selection function 37c. Specifically, the acquisition function 37d acquires the core phase data for reconstructing the CT image data of each selected optimum core phase. That is, the acquisition function 37d acquires the core phase data in each column in the body axis direction for each selected optimum core phase. The image reconstruction circuit 36 reconstructs the three-dimensional CT image data of the four optimum core phases by using the core phase data corresponding to the four acquired optimum core phases. The analysis function 37b executes the above-mentioned fluid analysis using the CT image data of the four reconstructed cardiac phases.

Here, in the X-ray CT apparatus 100 according to the first embodiment, it is also possible to present a warning when the optimum core phase selected by the selection function 37c does not meet a predetermined condition. Specifically, the presentation function 37e presents a warning to the operator when the plurality of cardiac phases selected by the selection function 37c do not meet a predetermined condition. For example, the presentation function 37e causes the display 32 to display a warning when the time interval between the upper and lower end core phases is shorter than a predetermined threshold value in the selected optimum core phase. In this case, the presentation function 37e can display a warning and present an alternative plan. For example, the presentation function 37e presents as an alternative the core phase in which the time interval between the upper and lower end core phases is longer than a predetermined threshold value and the movement associated with the beat is the smallest.

In the above-described embodiment, the case where the processing is executed by dividing the range of the core phase “70% to 99%” into four regions has been described. However, there are cases where the core phase data in the range of the core phase "70% to 99%" is not collected in the actual scan. Therefore, the selection function 37c can also divide the range of the actually collected cardiac phases. FIG. 9 is a diagram for explaining an example of the selection process by the selection function according to the first embodiment. For example, the selection function 37c divides the range of the actually collected cardiac phase from the projection data collected at the cardiac phase of 70% to 99% in the electrocardiographic synchronous scan into four regions, and the optimum phase in each region. Search and select. Then, the CT image data of the four optimum core phases is reconstructed from the core phase data corresponding to the four core phases selected from each region by the selection function 37c.

For example, when the actually collected range of cardiac phases is "68-95%", the selection function 37c divides "68-95%" into four regions. Here, the selection function 37c divides the regions so that the core phase included in each region does not exceed the range of "70% to 99%". For example, the selection function 37c does not target "68%" and "69%" of "68-95%", but "68-95%" is "70-76%" and "77-82%". , "83-88%" and "89-95%".

Further, in the above-described embodiment, a case where an image for one slice is generated from the core phase data and the optimum core phase search is performed has been described as an example. However, the embodiment is not limited to this, and may be, for example, a case where the CT image data corresponding to each core phase is reconstructed and the optimum core phase search is performed. In this case, for example, the selection function 37c can search for the optimum cardiac phase by generating an image of a slice containing a coronary artery from the reconstructed CT image data and comparing the SD values of the generated slices. Further, for example, the selection function 37c extracts a three-dimensional region of the coronary artery from the reconstructed CT image data, and searches for the optimum cardiac phase by comparing the SD values of the extracted three-dimensional region of the coronary artery (each voxel). You can also do it.

Further, in the above-described embodiment, the case where the optimum core phase is selected from each region has been described as an example. However, the embodiment is not limited to this, and for example, the upper end and the lower end of the range may be fixedly selected. As an example, the selection function 37c may be a case where the core phases "70%" and "99%" are fixedly selected as the optimum core phases in the range of the core phases "70% to 99%". Alternatively, the selection function 37c may select a core phase near the upper end and a core phase near the lower end in at least a range as a plurality of core phases. As an example, the selection function 37c preferentially selects the vicinity of the core phase "70%" and the vicinity of "99%" as the optimum core phase in the range of the core phase "70% to 99%". May be good.

Next, the procedure of processing by the X-ray CT apparatus 100 according to the first embodiment will be described. FIG. 10 is a flowchart showing a processing procedure by the X-ray CT apparatus 100 according to the first embodiment. Note that FIG. 10 shows a processing procedure when the range of the core phase of 70 to 99% is divided.

Here, step S101 in FIG. 10 is realized, for example, by the processing circuit 37 calling a program corresponding to the control function 37a from the storage circuit 35 and executing the program. Further, step S102, step S103, and step S107 are realized, for example, by the processing circuit 37 calling a program corresponding to the selection function 37c from the storage circuit 35 and executing the program. Further, steps S104 and S106 are realized, for example, by the processing circuit 37 calling a program corresponding to the presentation function 37e from the storage circuit 35 and executing the program. Further, step S105 is realized, for example, by the image reconstruction circuit 36 reading the corresponding program from the storage circuit 35 and executing it. Further, step S108 is realized, for example, by the processing circuit 37 calling a program corresponding to the analysis function 37b from the storage circuit 35 and executing the program.

In the X-ray CT apparatus 100 according to the present embodiment, first, the processing circuit 37 collects projection data (step S101). Then, the processing circuit 37 divides the cardiac phase 70 to 99% into a plurality of regions (step S102), and selects the cardiac phase with less movement of the coronary arteries in each region (step S103). Subsequently, the processing circuit 37 determines whether or not the selected core phase satisfies the condition (step S104). Here, when the selected core phase satisfies the condition (step S104 affirmative), the image reconstruction circuit 36 reconstructs the volume data corresponding to the selected core phase (step S105).

On the other hand, when the selected core phase does not satisfy the condition (negation in step S104), the processing circuit 37 displays a warning (step S106). Then, the processing circuit 37 determines whether or not the reselection operation has been accepted (step S107). Here, when the reselection operation is accepted (step S107 affirmative), the processing circuit 37 returns to step S103 and selects the cardiac phase with less movement of the coronary arteries. On the other hand, when the reselection operation is not accepted (denial in step S107), the image reconstruction circuit 36 reconstructs the volume data corresponding to the selected cardiac phase (step S105). When the volume data corresponding to each core phase is reconstructed in step S105, the processing circuit 37 executes the fluid analysis using the reconstructed volume data of each core phase (step S108).

As described above, according to the first embodiment, the data acquisition circuit 14 collects a plurality of projection data over time. The selection function 37c selects a plurality of heart phases from each time phase corresponding to the plurality of projection data so that the movement associated with the beat is relatively small and the time interval between the time phases is large. do. The acquisition function 37d acquires projection data corresponding to a plurality of core phases selected by the selection function 37c. Therefore, the X-ray CT apparatus 100 according to the first embodiment makes it possible to easily acquire appropriate data when performing fluid analysis.

Further, according to the first embodiment, the selection function 37c extracts a range of the cardiac phase in which the movement associated with the beat is relatively small in each time phase corresponding to the plurality of projected data, and includes the range in the extracted range. Based on the evaluation of the movement associated with the beat in the image data corresponding to the core phase, the movement associated with the beat is relatively small among the cardiac phases included in the range, and the movement associated with the beat is relatively small. Select multiple cardiac phases so that the time interval is large. Therefore, the X-ray CT apparatus 100 according to the first embodiment makes it possible to acquire more appropriate data when performing fluid analysis.

Further, according to the first embodiment, the selection function 37c evaluates the movement associated with the pulsation based on the sharpness in the coronary artery region included in the projection data. Therefore, the X-ray CT apparatus 100 according to the first embodiment makes it possible to easily evaluate the movement accompanying the pulsation.

Further, according to the first embodiment, the selection function 37c divides the range into a plurality of subranges, and for each subrange, the movement accompanying the pulsation is relatively from the cardiac phases included in the subrange. Select each small heart phase. Further, the selection function 37c divides the range into partial ranges so that the widths of the plurality of partial ranges are approximated. Therefore, the X-ray CT apparatus 100 according to the first embodiment makes it possible to easily select the cardiac phases with a certain interval.

Further, according to the first embodiment, the selection function 37c selects a core phase near the upper end and a core phase near the lower end in at least a range as a plurality of core phases. Therefore, the X-ray CT apparatus 100 according to the first embodiment makes it possible to easily select a cardiac phase in which the area of the coronary artery is maximized and a cardiac phase in which the area of the coronary artery is minimized.

Further, according to the first embodiment, the selection function 37c selects a plurality of core phases so that the time interval between the core phases is equal to or more than a predetermined threshold value in the core phases included in the range. Therefore, the X-ray CT apparatus 100 according to the first embodiment makes it possible to make the time intervals between the heart phases close to equal intervals.

Further, according to the first embodiment, the selection function 37c selects a plurality of core phases so that the time intervals between the adjacent core phases are large in the plurality of core phases and they are close to each other. Therefore, the X-ray CT apparatus 100 according to the first embodiment makes it possible to make the time interval between the core phases larger and closer to the equal interval.

Further, according to the first embodiment, the presentation function 37e presents a warning to the operator when the plurality of cardiac phases selected by the selection function 37c do not meet the predetermined conditions. Therefore, the X-ray CT apparatus 100 according to the first embodiment makes it possible to suppress the execution of fluid analysis using CT image data, which is not very appropriate, in advance.

(Second Embodiment)
Next, the second embodiment will be described. The configuration of the X-ray CT apparatus 100 according to the present embodiment is basically the same as the configuration of the X-ray CT apparatus 100 shown in FIG. Therefore, in the following description, the points different from the X-ray CT apparatus 100 according to the first embodiment will be mainly described, and the components having the same role as the components shown in FIG. 2 are designated by the same reference numerals. A detailed description will be omitted.

In the first embodiment described above, a case where the range of the core phase is divided into a plurality of regions and the optimum core phase is selected has been described as an example. In the second embodiment, a case where the optimum core phase is selected without dividing the range of the core phase will be described. For example, the X-ray CT apparatus 100 according to the second embodiment evaluates the movements associated with the pulsation for the whole core phase, and selects the optimum core phase based on the evaluation result.

FIG. 11 is a diagram for explaining an example of the selection process by the selection function 37c according to the second embodiment. FIG. 11 shows a case where the optimum core phase is selected from the range of 70 to 99% of the core phases. For example, the selection function 37c calculates the SD value described above for each 1% of the core phases in the range of 70 to 99% of the core phases. Then, as shown in FIG. 11, the selection function 37c selects the optimum core phase by ranking the SD values in ascending order with respect to each core phase. Here, the selection function 37c does not simply select in order from the highest-ranked core phase, but selects the optimum core phase in consideration of the time interval between the core phases. As an example, the optimum core phase is selected so that the time interval between the core phases is separated by "5%" or more and the evaluation rank based on the SD value is high.

In the second embodiment as well, the vicinity of the upper end and the vicinity of the lower end of the range (for example, 70 to 99%) may be preferentially selected as the optimum core phase. In this case, the selection function 37c first selects the core phase having a higher rank near the upper end and the lower end of the range as the optimum core phase. Then, the selection function 37c further selects the optimum core phase from the core phases separated from the selected optimum core phase by a predetermined time interval (for example, “5%”) or more.

Next, the procedure of processing by the X-ray CT apparatus 100 according to the second embodiment will be described. FIG. 12 is a flowchart showing a processing procedure by the X-ray CT apparatus 100 according to the second embodiment. Note that FIG. 12 shows a processing procedure when the optimum core phase is selected from the range of 70 to 99% of the core phases.

Here, step S201 in FIG. 12 is realized, for example, by the processing circuit 37 calling a program corresponding to the control function 37a from the storage circuit 35 and executing the program. Further, steps S202 and S203 are realized, for example, by the processing circuit 37 calling a program corresponding to the selection function 37c from the storage circuit 35 and executing the program. Further, step S204 is realized, for example, by the image reconstruction circuit 36 reading the corresponding program from the storage circuit 35 and executing it. Further, step S205 is realized, for example, by the processing circuit 37 calling a program corresponding to the analysis function 37b from the storage circuit 35 and executing the program.

In the X-ray CT apparatus 100 according to the present embodiment, first, the processing circuit 37 collects projection data (step S201). Then, the processing circuit 37 evaluates the movement in each core phase of 70 to 99% of the core phases (step S202). Then, the processing circuit 37 selects the core phase based on the small amount of movement and the time interval (step S203). After that, the image reconstruction circuit 36 reconstructs the volume data corresponding to the selected core phase (step S204). When the volume data corresponding to each core phase is reconstructed in step S204, the processing circuit 37 executes the fluid analysis using the reconstructed volume data of each core phase (step S205).

As described above, according to the second embodiment, the selection function 37c evaluates the movement associated with the beat for each core phase included in the range of the cardiac phases in which the movement associated with the beat is relatively small. Select the optimal core phase. Therefore, the X-ray CT apparatus 100 according to the second embodiment makes it possible to acquire appropriate data when performing fluid analysis.

(Third Embodiment)
By the way, although the first and second embodiments have been described so far, various different embodiments may be implemented in addition to the first and second embodiments described above.

The optimum core phase selection process described in the first and second embodiments described above can be executed at any timing. For example, the selection function 37c selects a plurality of optimum core phases at the time of data transfer. As an example, the selection function 37c selects the optimum central phase using the volume data when transferring the reconstructed volume data to the medical information processing apparatus 300 or the like. Alternatively, the selection function 37c selects a plurality of optimal core phases when the fluid analysis application is launched. As an example, the selection function 37c selects the optimum core phase when an operation for invoking a fluid analysis application is received via the input circuit 31. In this case, the selection function 37c may be the case of executing the selection process using the core phase data, or the case of executing the selection process using the volume data (CT image data).

Further, in the above-described embodiment, the case where the image quality index is used as the image index has been described as an example. However, the embodiment is not limited to this, and the X-ray CT apparatus 100 can use various image indexes. For example, the X-ray CT apparatus 100 can use the extraction ability of a site as an image index. The X-ray CT apparatus 100 can perform extraction processing of the shape of a portion such as the blood vessel shape data described above. Here, the accuracy of extracting the site from the CT image data changes according to the state of the collected CT image data. For example, if the movement associated with the beating of the heart is large, the accuracy of extracting the site may decrease. That is, the X-ray CT apparatus 100 according to the third embodiment uses the extraction ability of the portion caused by such image data as an image index.

Specifically, the selection function 37c according to the third embodiment is a CT image data used for fluid analysis from a combination of CT image data based on the extraction result of a predetermined portion included in each CT image data. Extract pairs. Here, the selection function 37c uses, for example, the blood vessel wall of the coronary artery or the core wire of the coronary artery as a predetermined site. Hereinafter, an example of selection of a plurality of time phases (selection of a set of CT image data) based on the extraction ability of these parts will be described.

Here, first, in the X-ray CT apparatus 100 according to the third embodiment, the CT image data of each time phase is reconstructed at the time of extracting the site. That is, the image reconstruction circuit 36 reconstructs the CT image data corresponding to each cardiac phase from the collected projection data for a plurality of heartbeats. For example, the image reconstruction circuit 36 reconstructs the CT image data of each core phase from each core phase data of 70% to 99% of the core phases.

When the CT image data of each core phase is reconstructed, the analysis function 37b extracts a site from the CT image data of each core phase. Here, the analysis function 37b can extract a site from the CT image data of each core phase by various methods. For example, the analysis function 37b extracts the blood vessel wall and the core wire by performing an extraction process on each CT image data. That is, the analysis function 37b extracts each part from all the CT image data by extracting the part from all the CT image data reconstructed by the image reconstruction circuit 36. The analysis function 37b can appropriately use an existing algorithm as an extraction algorithm used for site extraction.

Further, the analysis function 37b extracts a part from the CT image data of one heart phase, and aligns the CT image data obtained by extracting the part with the CT image data of another heart phase to obtain the other heart phase. It is also possible to extract a part in the CT image data. In such a case, the analysis function 37b first extracts the blood vessel wall and the core wire by performing an extraction process on the CT image data of one heart phase. Next, the analysis function 37b aligns the CT image data extracted from the blood vessel wall and the core wire with the CT image data of another cardiac phase. For example, the analysis function 37b extracts feature points from the CT image data to be aligned and executes a non-rigid body alignment process that deforms the extracted feature points in order to match them.

As an example, the analysis function 37b extracts corresponding feature points (anatomical feature points) from the CT image data obtained by extracting the blood vessel wall and the core wire and the CT image data of another cardiac phase. Then, the analysis function 37b calculates the coordinate conversion information for matching the extracted feature points. For example, the analysis function 37b calculates coordinate conversion information in a three-dimensional coordinate system for matching feature points in CT image data of other cardiac phases with feature points in CT image data from which blood vessel walls and core wires are extracted. That is, the analysis function 37b calculates the conversion information for calculating the position corresponding to each position of the CT image data from which the blood vessel wall and the core wire are extracted in the CT image data of other cardiac phases. The analysis function 37b can specify the coordinates of the blood vessel wall and the core wire in the CT image data of other cardiac phases by using the conversion information with respect to the coordinates of the extracted blood vessel wall and the core wire.

As described above, when the site is extracted, the selection function 37c selects a plurality of time phases (a set of CT image data) based on the extraction result. Hereinafter, an example in which the extraction result of the blood vessel wall of the coronary artery is used and an example in which the extraction result of the core wire of the coronary artery is used will be described in order. For example, the selection function 37c selects a plurality of time phases based on the variation in the cross-sectional area of the blood vessel wall extracted by the analysis function 37b. FIG. 13 is a diagram for explaining the selection of the time phase by the selection function 37c according to the third embodiment. Here, in FIG. 13, the horizontal axis shows the time phase, and the horizontal axis shows the cross-sectional area. For example, the selection function 37c calculates the cross-sectional area of a predetermined cross section of the blood vessel wall extracted by the analysis function 37b for each CT image data, as shown by the points in the graph of FIG. Then, the selection function 37c compares the inclination of the straight line L1 indicating a general change in the cross-sectional area of the coronary artery with the calculated cross-sectional area of each core phase, and has an inappropriate cardiac phase as a change over time in the cross-sectional area. Exclude CT image data from the selection. For example, the selection function 37c excludes the CT image data of the cardiac phase P1 shown in FIG. 13 from the selection target. That is, the selection function 37c compares the values of the adjacent cross-sectional areas with each other, and excludes the CT image data of the cardiac phase having a large degree of deviation from the values of the adjacent cross-sectional areas from the selection target.

As an example, the selection function 37c first starts from the four regions of "70 to 76%", "77% to 83%", "84% to 91%", and "92 to 99%" between the heart phases. The core phases are selected so that the time interval of is equal to or greater than a predetermined threshold value. Then, the selection function 37c calculates the cross-sectional area at each selected core phase and compares them with each other. Further, the selection function 37c determines whether or not the cross-sectional area has changed beyond the permissible range based on the inclination of the straight line L1. Here, when the change in the cross-sectional area in each selected core phase does not exceed the permissible range based on the inclination of the straight line L1, the selection function 37c is set to "70 to 76%", "77% to 83%", and "84". The core phase selected from the four regions of "% to 91%" and "92 to 99%" is determined as the optimum core phase.
On the other hand, when the change in the cross-sectional area in each of the selected core phases exceeds the permissible range based on the slope of the straight line L1, the selection function 37c reselects the core phases based on a predetermined condition. For example, when the change in the cross-sectional area in the core phase selected from "77% to 83%" exceeds the permissible range, the selection function 37c selects the core phase again from "77% to 83%". Here, the selection function 37c starts from "77% to 83%" so as to maintain the time interval with the selected cardiac phase as much as possible in the adjacent regions "70 to 76%" and "84% to 91%". Reselect the cardiac phase.

For example, the selection function 37c selects the adjacent core phase of the core phase determined to be inappropriate when reselecting the core phase. For example, if "79%" was selected in the first selection, the selection function 37c selects the "78%" or "80%" cardiac phase.

Alternatively, the selection function 37c selects the core phases separated by a predetermined number of phases (for example, 3%) when reselecting the core phases. For example, if "79%" was selected in the first selection, the selection function 37c selects the "82%" cardiac phase. As described above, the accuracy of extracting the site from the CT image data may decrease when the movement is large. Therefore, when the adjacent heart phases of the heart phases determined to be inappropriate are reselected, the reselected heart phases may also be inappropriate. Therefore, the selection function 37c can perform reselection with high accuracy by selecting the core phases separated by a predetermined number of phases as described above.

The selection function 37c may be a case where the time interval between the four core phases is readjusted when the core phases are reselected. For example, when the core phase of "79%" is regarded as inappropriate and the core phase of "82%" is reselected, the selection function 37c has already been selected from "84% to 91%" and "92 to 99%". Reselect the cardiac phase. That is, the selection function 37c reselects the core phase at "84% to 91%" and the core phase at "92 to 99%" so that the time interval between the core phases becomes wider.

Further, in the above-mentioned example, a case where the cross-sectional areas of the coronary arteries in each cardiac phase selected from the four regions are calculated and compared with each other has been described. However, the embodiment is not limited to this, and may be a case where the cross-sectional lines of the coronary arteries in all the cardiac phases are calculated and compared with each other. In such a case, for example, the selection function 37c calculates the cross-sectional lines of the coronary arteries in all the cardiac phases, and sets the cardiac phases in which the change in the cross-sectional area does not exceed the allowable range based on the inclination of the straight line L1. Select so that the time interval of is wider.

Further, in the above-mentioned example, the case where the extraction of the blood vessel wall of the coronary artery is determined by using the cross-sectional area has been described. However, the embodiment is not limited to this, and for example, it may be used whether or not the blood vessel wall of the coronary artery has been extracted. In such a case, for example, the selection function 37c excludes the CT image data from which the blood vessel wall has not been extracted from the selection target. Further, for example, the selection function 37c can also determine the accuracy of extraction of the blood vessel wall by using the similarity of the contour of the blood vessel wall. In such a case, for example, the selection function 37c compares the contour of the blood vessel wall in the cardiac phase to be determined with the contour of the blood vessel wall in the adjacent cardiac phases, and when the similarity is both below a predetermined threshold value, Exclude the heart phase of the judgment target from the selection target.

Next, a case where the extraction result of the core wire of the coronary artery is used will be described. In such a case, for example, the selection function 37c determines the accuracy of the core wire extraction by comparing the lengths of the core wires of the coronary arteries extracted by the analysis function 37b. For example, when each core wire is extracted from all CT image data, the extraction of the core wire may fail and become shorter. The selection function 37c calculates the length of each core wire extracted from the CT image data of each core phase. Then, the selection function 37c compares the calculated core wire lengths between the core phases, and excludes the core phases having the core wire length shorter than the others from the selection target.

In the above-mentioned example, a case where the selection function 37c automatically reselects based on the extracted blood vessel wall and core wire has been described. However, the embodiment is not limited to this, and may be, for example, a case where the extraction result is presented to the operator and an instruction for reselection is received. In such a case, for example, the presentation function 37e causes the display 32 to display the result of the extraction process of the portion by the analysis function 37b. The operator refers to the result of the extraction process displayed on the display 32 and determines whether or not to perform reselection. Then, the operator inputs an instruction as to whether or not to perform reselection via the input circuit 31. Here, when the input circuit 31 receives an instruction to perform reselection, the selection function 37c reselects the core phase. On the other hand, when the input circuit 31 receives an instruction not to perform reselection, the analysis function 37b performs fluid analysis using the CT image data of the selected cardiac phase.

In the above, an example in which the extraction ability of a part is used as an image index has been described. Next, the procedure of processing by the X-ray CT apparatus 100 according to the third embodiment will be described. FIG. 14 is a flowchart showing a processing procedure by the X-ray CT apparatus 100 according to the third embodiment. Note that FIG. 14 shows a processing procedure when the ability to extract the blood vessel wall of the coronary artery is used as an image index.

Here, step S301 in FIG. 14 is realized, for example, by the processing circuit 37 calling a program corresponding to the control function 37a from the storage circuit 35 and executing the program. Further, step S302 is realized, for example, by the image reconstruction circuit 36 reading the corresponding program from the storage circuit 35 and executing it. Further, steps S303 and 307 are realized, for example, by the processing circuit 37 calling a program corresponding to the analysis function 37b from the storage circuit 35 and executing the program. Further, step S304, step S305 and step S310 are realized, for example, by the processing circuit 37 calling a program corresponding to the selection function 37c from the storage circuit 35 and executing the program. Further, steps S306 and S308 are realized, for example, by the processing circuit 37 calling a program corresponding to the presentation function 37e from the storage circuit 35 and executing the program.

In the X-ray CT apparatus 100 according to the present embodiment, first, the processing circuit 37 collects projection data (step S301). Then, the image reconstruction circuit 36 reconstructs the volume data of each core phase (step S302). Subsequently, the processing circuit 37 extracts the vessel wall of the coronary artery from the reconstructed volume data of each cardiac phase (step S303). Then, the processing circuit 37 divides the core phase 70 to 99% into a plurality of regions (step S304), and selects the core phase in each region (step S305).

Subsequently, the processing circuit 37 determines whether or not the selected core phase satisfies the condition (step S306). Here, when the selected core phase satisfies the condition (affirmation in step S306), the processing circuit 37 executes the fluid analysis using the volume data of each selected core phase (step S307).

On the other hand, when the selected core phase does not satisfy the condition (denial in step S306), the processing circuit 37 displays a warning (step S308) and determines whether or not the reselection operation has been accepted (step S309). .. Here, when the reselection operation is accepted (step S309 affirmative), the processing circuit 37 reselects the phase based on the condition (step S310). On the other hand, when the reselection operation is not accepted (denial in step S309), the processing circuit 37 executes the fluid analysis using the volume data of each selected core phase (step S307).

Further, in the above-described embodiment, the case where the X-ray CT apparatus 100 executes various processes has been described. However, the embodiment is not limited to this, and may be, for example, a case where various processes are executed in the medical information processing apparatus 300. FIG. 13 is a diagram showing an example of the configuration of the medical information processing apparatus 300 according to the third embodiment.

For example, as shown in FIG. 13, the medical information processing apparatus 300 includes an I / F (interface) circuit 310, a storage circuit 320, an input circuit 330, a display 340, and a processing circuit 350.

The I / F circuit 310 controls the transmission and communication of various data performed between the various X-ray CT devices 100 or the image storage device 200 connected to the processing circuit 350 and connected via the network 400. For example, the I / F circuit 310 is realized by a network card, a network adapter, a NIC (Network Interface Controller), or the like. In the present embodiment, the I / F circuit 310 receives CT image data from the X-ray CT device 100 or the image storage device 200, and outputs the received CT image data to the processing circuit 350.

The storage circuit 320 is connected to the processing circuit 350 and stores various data. For example, the storage circuit 320 is realized by a semiconductor memory element such as a RAM (Random Access Memory) or a flash memory, a hard disk, an optical disk, or the like. In the present embodiment, the storage circuit 320 stores CT image data received from the X-ray CT device 100 or the image storage device 200.

The input circuit 330 is connected to the processing circuit 350, converts the input operation received from the operator into an electric signal, and outputs the input operation to the processing circuit 350. For example, the input circuit 330 is realized by a trackball, a switch button, a mouse, a keyboard, a touch panel, and the like.

The display 340 is connected to the processing circuit 350 and displays various information and various image data output from the processing circuit 350. For example, the display 340 is realized by a liquid crystal monitor, a CRT (Cathode Ray Tube) monitor, a touch panel, or the like.

The processing circuit 350 controls each component of the image processing device 300 in response to an input operation received from the operator via the input circuit 330. For example, the processing circuit 350 is realized by a processor. In the present embodiment, the processing circuit 350 stores the CT image data output from the I / F circuit 310 in the storage circuit 320. Further, the processing circuit 350 reads CT image data from the storage circuit 320 and displays it on the display 340.

Then, as shown in FIG. 13, the processing circuit 350 executes the control function 351, the selection function 352, the acquisition function 353, the presentation function 354, and the analysis function 355. The control function 351 controls the entire medical information processing apparatus 300. The selection function 352 executes the same processing as the selection function 37c described above. The acquisition function 353 executes the same processing as the acquisition function 37d described above. The presentation function 354 executes the same processing as the presentation function 37e described above. The analysis function 355 executes the same processing as the analysis function 37b described above.

In the above-described embodiment, an example in which each processing function is realized by a single processing circuit (processing circuit 37 and processing circuit 350) has been described, but the embodiment is not limited to this. For example, the processing circuit 37 and the processing circuit 350 may be configured by combining a plurality of independent processors, and each processor may execute each program to realize each processing function. Further, each processing function of the processing circuit 37 and the processing circuit 350 may be appropriately distributed or integrated into a single or a plurality of processing circuits.

The word "processor" used in the description of each of the above-described embodiments is, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an integrated circuit for a specific application (Application Specific Integrated Circuit: ASIC), or a programmable device. It means a circuit such as a logical device (for example, a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA)). do. Here, instead of storing the program in the storage circuit, the program may be configured to be directly embedded in the circuit of the processor. In this case, the processor realizes the function by reading and executing the program embedded in the circuit. Further, each processor of the present embodiment is not limited to the case where each processor is configured as a single circuit, and a plurality of independent circuits may be combined to be configured as one processor to realize its function. good.

Here, the program executed by the processor is provided in advance in a ROM (Read Only Memory), a storage unit, or the like. This program is a file in a format that can be installed or executed on these devices, such as CD (Compact Disk) -ROM, FD (Flexible Disk), CD-R (Recordable), DVD (Digital Versatile Disk), etc. It may be recorded and provided on a computer-readable storage medium. Further, this program may be provided or distributed by being stored on a computer connected to a network such as the Internet and downloaded via the network. For example, this program is composed of modules including each functional part. In actual hardware, the CPU reads a program from a storage medium such as a ROM and executes it, so that each module is loaded on the main storage device and generated on the main storage device.

According to at least one embodiment described above, appropriate data can be easily selected.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, as well as in the scope of the invention described in the claims and the equivalent scope thereof.

100 X-ray CT device 37b, 355 Analysis function 37c, 352 Selection function 37d, 353 Acquisition function 37e, 354 Presentation function 300 Medical information processing device

Claims (20)

A collection unit that collects image data related to multiple time phases, including at least a part of the coronary arteries of the heart.
An image index relating to a plurality of the image data included in the extracted time phase is extracted by extracting a time phase in which the change in the shape of the coronary artery is relatively large and the movement accompanying the beat is relatively small in the period of one heartbeat. Of the plurality of the image data included in the extracted time phase based on the image index in each image data, the image data is obtained from a combination of image data having a time interval larger than a predetermined time interval. A selection part to extract pairs and
Changes in the shape of the coronary arteries are extracted based on the set of extracted image data, fluid analysis is performed on the coronary arteries based on the set of image data and changes in the shape of the coronary arteries, and fluid parameters related to the coronary arteries are performed. And the analysis department that finds
An X-ray CT apparatus. The selection unit extracts a period in which the change in the shape of the coronary artery is relatively large during the period of one heartbeat, and extracts a time phase in which the movement associated with the beat is relatively small in the extracted period. The X-ray CT apparatus according to 1. A claim that the selection unit extracts a set of image data from the time phases included in the period, which is a time phase in which the movement associated with the pulsation is relatively small and the time interval between the time phases is large. 2. The X-ray CT apparatus according to 2. The X-ray CT apparatus according to any one of claims 1 to 3, wherein the selection unit extracts a set of the image data from the time phase that becomes the Wave Free Period in the heartbeat time phase of one heartbeat. The X-ray CT apparatus according to any one of claims 1 to 3, wherein the selection unit extracts a set of the image data from 70% or more of the cardiac time phase in the heartbeat time phase of one heartbeat. The X according to any one of claims 1 to 5 , wherein the selection unit extracts a set of image data in which the image quality index in each image data is equal to or higher than a predetermined threshold value from the combination of the image data. Line CT device. The selection unit is one of claims 1 to 5 , which extracts a set of the image data from the combination of the image data based on the extraction result of a predetermined portion included in each image data. The X-ray CT apparatus described. The X-ray CT apparatus according to claim 7 , wherein the predetermined site is a blood vessel wall of the coronary artery or a core wire of the coronary artery. Based on the image index, the selection unit evaluates the movement of each image data of the time phase included in the Wave Free Period associated with the beating of the heart, and the time phase in which the movement accompanying the beating is relatively small. The X-ray CT apparatus according to any one of claims 1 to 3, which extracts a set of image data of the above. The X-ray CT apparatus according to claim 9 , wherein the selection unit evaluates the movement associated with the pulsation based on the sharpness in the coronary artery region included in the image data. The selection unit divides the Wave Free Period into a plurality of subranges, and for each subrange, corresponds to a time phase in which the movement associated with the pulsation is relatively small from among the time phases included in the subrange. The X-ray CT apparatus according to claim 9 or 10 , wherein a set of image data is extracted. The X-ray CT apparatus according to claim 11 , wherein the selection unit divides the Wave Free Period into the partial ranges so that the widths of the plurality of partial ranges are approximated to each other. The X-ray CT apparatus according to claim 9 or 10 , wherein the selection unit extracts image data corresponding to at least the time phase near the upper end and the time phase near the lower end in the Wave Free Period as a set of the image data. The selection unit, in the time phase included in the Wave the Free Period, so that the time interval when the interphase is greater than or equal to a predetermined threshold value, and extracts the image data corresponding to the time phase of multiple, claim 9 or 10 The X-ray CT apparatus described. The selection unit is any one of claims 1 to 14 that extracts the set of image data so that each time interval between adjacent time phases in the set of image data is large and approximates each other. The X-ray CT apparatus according to. The X-ray CT apparatus according to any one of claims 1 to 15 , wherein the selection unit extracts a set of the image data at the time of transferring the image data. The X-ray CT apparatus according to any one of claims 1 to 15 , wherein the selection unit extracts a set of the image data when the application for fluid analysis is started. The X according to any one of claims 1 to 17 , further comprising a presentation unit that presents a warning to the operator when the set of image data extracted by the selection unit does not meet a predetermined condition. Line CT device. An acquisition unit that acquires image data related to multiple time phases, including at least a part of the coronary arteries of the heart,
An image index relating to a plurality of the image data included in the extracted time phase is extracted by extracting a time phase in which the change in the shape of the coronary artery is relatively large and the movement accompanying the beat is relatively small in the period of one heartbeat. Of the plurality of the image data included in the extracted time phase based on the image index in each image data, the image data is obtained from a combination of image data having a time interval larger than a predetermined time interval. A selection part to extract pairs and
Changes in the shape of the coronary arteries are extracted based on the set of extracted image data, fluid analysis is performed on the coronary arteries based on the set of image data and changes in the shape of the coronary arteries, and fluid parameters related to the coronary arteries are performed. And the analysis department that finds
To prepare
Medical information processing device. The acquisition step of acquiring image data relating to multiple time phases, including at least a part of the coronary arteries of the heart,
An image index relating to a plurality of the image data included in the extracted time phase is extracted by extracting a time phase in which the change in the shape of the coronary artery is relatively large and the movement accompanying the beat is relatively small in the period of one heartbeat. Of the plurality of the image data included in the extracted time phase based on the image index in each image data, the image data is obtained from a combination of image data having a time interval larger than a predetermined time interval. Selection steps to extract pairs and
Changes in the shape of the coronary arteries are extracted based on the set of extracted image data, fluid analysis is performed on the coronary arteries based on the set of image data and changes in the shape of the coronary arteries, and fluid parameters related to the coronary arteries are performed. Analysis step to find
A medical information processing program that lets a computer execute.

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