JP7139156B2 - X-ray CT device - Google Patents

Description

An embodiment of the present invention relates to an X-ray CT apparatus.

X-ray CT (Computed Tomography) equipment detects electrocardiographic waveform data in real time from an electrocardiograph attached to the subject when the imaging target is the heart, and determines the imaging timing based on the R wave of the electrocardiographic waveform data. synchronize. Specifically, the X-ray CT apparatus performs imaging in synchronization with the resting phase of the heart based on the R wave and heart rate.

In the case of imaging for blood vessel observation such as coronary artery CTA (CT Angiography), the injector is connected to the subject in addition to the attachment of the electrocardiograph during imaging preparation. The X-ray CT apparatus performs monitoring imaging for observing the concentration of the contrast medium after injection of the contrast medium from the injector. During monitoring imaging, the X-ray CT apparatus detects a CT value that increases according to the concentration of the injected contrast agent in the region of interest (ROI) of the cross-sectional image, and triggers when the CT value reaches a threshold value. Move to main scan automatically or manually. Although the monitoring imaging does not contribute to diagnosis, it contributes to improving the quality of the CT image obtained by the main scan by enabling the shift to the main scan when the contrast medium concentration is high. After shifting to the main scan, the X-ray CT apparatus performs imaging in a short imaging time based on the first R wave.

Here, in the case of CT imaging for angiography, setup for connecting the electrocardiograph and the injector takes longer than the imaging time of the main scan. For example, the imaging time for blood vessel observation is shorter than the imaging time for wide-range imaging using functional analysis using dynamic imaging or helical imaging. However, in the case of CT imaging for blood vessel observation, despite the short imaging time, the same set-up as for functional analysis and wide-area imaging is required, so the flow of imaging work (hereinafter referred to as workflow) cannot be improved. It is in.

JP 2009-153965 A

The problem to be solved by the invention is to improve the workflow of CT imaging for blood vessel observation.

An X-ray CT apparatus according to an embodiment includes a memory, a first estimator, a second estimator, and a controller.
The memory stores a plurality of medical image data captured over time while a contrast agent is injected into the subject.
The first estimation unit estimates a stationary phase of the subject's heart from the plurality of pieces of medical image data.
The second estimating unit estimates the timing of the stationary phase at a time when an index value of the concentration of the contrast agent in each pixel of the region of interest of the plurality of medical image data is equal to or greater than a threshold.
The control unit controls the imaging system to perform the main scan based on the timing.

FIG. 1 is a block diagram showing the configuration of the X-ray CT apparatus according to the first embodiment. FIG. 2 is a flow chart for explaining the operation in the first embodiment. FIG. 3 is a schematic diagram showing the setup situation around the subject in the first embodiment. FIG. 4 is a flow chart for explaining the operation of the modification of the first embodiment. FIG. 5 is a schematic diagram of TDC and motion graphs for explaining the operation of the modification of the first embodiment. FIG. 6 is a schematic diagram for explaining the concept of stationary phase estimation in the second embodiment. FIG. 7 is a schematic diagram for explaining a static phase estimation method according to the second embodiment. FIG. 8 is a schematic diagram for explaining a static phase estimation method according to the second embodiment. FIG. 9 is a schematic diagram for explaining a static phase estimation method according to the second embodiment. FIG. 10 is a flow chart for explaining the operation in the third embodiment. FIG. 11 is a schematic diagram for explaining the concept of imaging timing in the third embodiment. FIG. 12 is a schematic diagram for explaining the concept of imaging timing in the third embodiment. FIG. 13 is a flow chart for explaining the operation of the modification of the third embodiment. FIG. 14 is a flow chart for explaining the operation of another modification of the third embodiment.

An X-ray CT apparatus according to each embodiment will be described below with reference to the drawings. The X-ray CT apparatus includes a Rotate/Rotate-Type (3rd generation CT) in which the X-ray tube and X-ray detector are rotated around the subject as a unit, and a large number of X-rays arrayed in a ring. There are various types such as Stationary/Rotate-Type (4th generation CT) in which the detection element is fixed and only the X-ray tube rotates around the subject, and any type can be applied to the embodiment. Each of the following embodiments will be described by taking the third generation CT as an example.

<First Embodiment>
FIG. 1 is a block diagram showing the configuration of the X-ray CT apparatus according to the first embodiment. The X-ray CT apparatus 1 irradiates a subject P with X-rays from an X-ray source having an X-ray tube 11 , and an X-ray detector 12 detects the X-rays transmitted through the subject. The X-ray CT apparatus 1 generates a CT image of the subject P based on the output from the X-ray detector 12 . The X-ray source and X-ray detector 12 are an example of an imaging system.

The X-ray CT apparatus 1 shown in FIG. 1 has a gantry device 10 , a bed device 30 and a console device 40 . The gantry device 10 is a scanning device having a configuration for X-ray CT imaging of the subject P. As shown in FIG. Note that the plurality of gantry devices 10 depicted in FIG. 1 show the front and side surfaces of one gantry device 10 . The bed device 30 is a device for placing a subject P to be subjected to X-ray CT imaging and moving it to a position where X-ray CT imaging is performed. The console device 40 is a computer that controls the gantry device 10 .

For example, the gantry device 10 and the bed device 30 are installed in a CT examination room, and the console device 40 is installed in a control room adjacent to the CT examination room. Note that the console device 40 does not necessarily have to be installed in the control room. For example, the console device 40 may be installed in the same room together with the gantry device 10 and the bed device 30 . In any case, the gantry device 10, the bed device 30, and the console device 40 are connected by wire or wirelessly so as to be able to communicate with each other.

The gantry device 10 has an X-ray tube 11 , an X-ray detector 12 , a rotating frame 13 , an X-ray high voltage device 14 , a control device 15 , a wedge 16 , a collimator 17 and a DAS 18 .

The X-ray tube 11 is a vacuum tube that generates X-rays by irradiating thermal electrons from a cathode (filament) to an anode (target) by applying a high voltage and supplying a filament current from an X-ray high voltage device 14. is. For example, the X-ray tube 11 is a rotating anode type X-ray tube that generates X-rays by irradiating a rotating anode with thermal electrons. The X-rays generated by the X-ray tube 11 are shaped into a cone beam via a collimator 17 and irradiated onto the subject P. As shown in FIG. Note that the X-ray tube 11 and the collimator 17 are examples of an X-ray source.

The X-ray detector 12 detects X-rays emitted from the X-ray tube 11 and passed through the subject P, and outputs an electrical signal corresponding to the X-ray dose to the DAS 18 . The X-ray detector 12 has, for example, a plurality of X-ray detection element arrays in which a plurality of X-ray detection elements are arranged in the channel direction along one circular arc around the focal point of the X-ray tube. The X-ray detector 12 has, for example, a structure in which a plurality of X-ray detection element arrays each having a plurality of X-ray detection elements arranged in the channel direction are arranged in the slice direction (column direction, row direction). Also, the X-ray detector 12 is, for example, an indirect conversion type detector having a grid, a scintillator array, and a photosensor array. The scintillator array has a plurality of scintillators, and each scintillator has a scintillator crystal that outputs a photon amount of light corresponding to the amount of incident X-rays. The grid has an X-ray shielding plate arranged on the surface of the scintillator array on the X-ray incident side and having a function of absorbing scattered X-rays. Note that the grid may also be called a collimator (one-dimensional collimator or two-dimensional collimator). The photosensor array has a function of converting the amount of light from the scintillator into an electrical signal, and includes photosensors such as photomultiplier tubes (PMTs). The X-ray detector 12 may be a direct conversion type detector (semiconductor detector) having a semiconductor element that converts incident X-rays into electrical signals.

The rotating frame 13 supports the X-ray source and the X-ray detector 12 so as to be rotatable around the rotation axis. Specifically, the rotating frame 13 is an annular frame that supports the X-ray tube 11 and the X-ray detector 12 so as to face each other and rotates the X-ray tube 11 and the X-ray detector 12 by means of a control device 15, which will be described later. is. The rotating frame 13 is rotatably supported by a fixed frame (not shown) made of metal such as aluminum. Specifically, the rotating frame 13 is connected to the edges of the stationary frame via bearings. In this embodiment, the rotation axis of the rotating frame 13 in the non-tilt state or the longitudinal direction of the top plate 33 of the bed apparatus 30 is the Z-axis direction, and the axial direction perpendicular to the Z-axis direction and horizontal to the floor surface is are defined as the X-axis direction, the axis direction perpendicular to the Z-axis direction, and the Y-axis direction as the axis direction perpendicular to the floor surface. The rotating frame 13 receives power from the drive mechanism of the control device 15 and rotates around the rotation axis Z at a constant angular velocity. In addition to the X-ray tube 11 and the X-ray detector 12, the rotating frame 13 further includes an X-ray high-voltage device 14 and a DAS 18 to support them. Such a rotating frame 13 is accommodated in a substantially cylindrical housing having an opening (bore) forming an imaging space. The aperture approximately matches the FOV19. The central axis of the opening coincides with the rotational axis Z of the rotating frame 13 . The rotation axis Z of the rotating frame 13 may also be called the rotation axis Z of the X-ray tube 11 . The detection data generated by the DAS 18 is transmitted by optical communication from a transmitter having a light emitting diode (LED) mounted on a rotating frame to a receiver having a photodiode mounted on a non-rotating portion (e.g., fixed frame) of the gantry. machine and transferred to the console device 40 . The method of transmitting the detected data from the rotating frame to the non-rotating portion of the gantry is not limited to the optical communication described above, and any method of non-contact data transmission may be adopted.

The X-ray high voltage device 14 has electric circuits such as a transformer and a rectifier, and has a function of generating a high voltage to be applied to the X-ray tube 11 and a filament current to be supplied to the X-ray tube 11. It has a generating device and an X-ray control device for controlling the output voltage according to the X-rays emitted by the X-ray tube 11 . The high voltage generator may be of a transformer type or an inverter type. The X-ray high-voltage device 14 may be provided on the rotating frame 13 or may be provided on the fixed frame (not shown) side of the gantry device 10 .

The control device 15 has a processing circuit having a CPU (Central Processing Unit) and the like, and drive mechanisms such as motors and actuators. The processing circuit has, as hardware resources, a processor such as a CPU or an MPU (Micro Processing Unit) and a memory such as a ROM (Read Only Memory) or a RAM (Random Access Memory). In addition, the control device 15 includes an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), and other complex programmable logic devices (Complex Programmable Logic Device: CPLD ), which may be implemented by a Simple Programmable Logic Device (SPLD). The control device 15 controls the X-ray high-voltage device 14, the DAS 18, etc. according to commands from the console device 40. FIG. The processor implements the control by reading and executing the program stored in the memory. The control device 15 also has a function of receiving an input signal from an input interface 43 (described later) attached to the console device 40 or the gantry device 10 and controlling the operations of the gantry device 10 and the bed device 30 . For example, the control device 15 receives an input signal and performs control to rotate the rotating frame 13 , control to tilt the gantry device 10 , and control to operate the bed device 30 and the tabletop 33 . Note that the control for tilting the gantry device 10 is performed by the control device 15 based on the tilt angle (tilt angle) information input through the input interface attached to the gantry device 10, so as to rotate the rotating frame 13 about an axis parallel to the X-axis direction. This is achieved by rotating the Note that the control device 15 may be provided in the gantry device 10 or may be provided in the console device 40 . Instead of storing the program in the memory, the control device 15 may be configured to directly incorporate the program into the circuit of the processor. In this case, the processor implements the above control by reading and executing the program incorporated in the circuit.

Wedge 16 is a filter for adjusting the dose of X-rays emitted from X-ray tube 11 . Specifically, the wedge 16 transmits and attenuates the X-rays irradiated from the X-ray tube 11 so that the X-rays irradiated from the X-ray tube 11 to the subject P have a predetermined distribution. It is a filter that For example, the wedge 16 (wedge filter, bow-tie filter) is a filter processed from aluminum to have a predetermined target angle and a predetermined thickness.

The collimator 17 is a lead plate or the like for narrowing down the irradiation range of the X-rays transmitted through the wedge 16, and a slit is formed by combining a plurality of lead plates or the like. Note that the collimator 17 may also be called an X-ray diaphragm.

A DAS 18 (Data Acquisition System) acquires digital values indicating the intensity of X-rays attenuated by the subject P for each view. The DAS 18 has an amplifier that amplifies the electrical signal output from each X-ray detection element of the X-ray detector 12, and an A/D converter that converts the amplified electrical signal into a digital signal. , to generate detection data having a digital value indicated by the digital signal. Detected data is a set of digital values of x-ray intensity identified by the channel number of the x-ray detector element from which it was generated, the row number, and the view number indicating the acquired view. As the view number, the order in which the views were acquired (acquisition time) may be used, or a number representing the rotation angle of the X-ray tube 11 (eg, 1 to 1000) may be used. Also, the detection data generated by the DAS 18 is transferred to the console device 40 via a non-contact data transmission circuit (not shown) accommodated in the gantry device 10 . Also, the DAS is an example of a data collector.

The bed device 30 is a device for placing and moving a subject P to be scanned, and includes a base 31 , a bed driving device 32 , a top board 33 and a support frame 34 .

The base 31 is a housing that supports the support frame 34 so as to be vertically movable.

The bed driving device 32 is a motor or actuator that moves the table 33 on which the subject P is placed in the longitudinal direction of the table 33 . The bed driving device 32 moves the tabletop 33 under the control of the console device 40 or the control device 15 . For example, the bed driving device 32 moves the top plate 33 in a direction orthogonal to the subject P so that the body axis of the subject P placed on the top plate 33 coincides with the central axis of the opening of the rotating frame 13 . do. Further, the bed driving device 32 may move the top board 33 along the body axis direction of the subject P according to the X-ray CT imaging performed using the gantry device 10 .

A top plate 33 provided on the upper surface of the support frame 34 is a plate on which the subject P is placed. Note that the bed driving device 32 may move the support frame 34 in the longitudinal direction of the top plate 33 in addition to the top plate 33 .

The console device 40 has a memory 41 , a display 42 , an input interface 43 , a processing circuit 44 and a communication interface 45 . Data communication between the memory 41, the display 42, the input interface 43, the processing circuit 44, and the communication interface 45 is performed via a bus (BUS). Although the console device 40 is described as being separate from the gantry device 10 , the console device 40 or a part of each component of the console device 40 may be included in the gantry device 10 .

The memory 41 is implemented by, for example, a RAM (Random Access Memory), a semiconductor memory device such as a flash memory, a hard disk, an optical disk, or the like. The memory 41 stores projection data and medical image data, for example. In this embodiment, the memory 41 stores a plurality of medical image data captured over time while the subject P is injected with a contrast medium. The memory 41 also stores control programs, data, and the like according to the present embodiment. Also, the storage area of the memory 41 may be in the X-ray CT apparatus 1 or in an external storage device connected via a network. The memory 41 is an example of a storage unit.

The display 42 displays various information. For example, the display 42 outputs a medical image (CT image) generated by the processing circuit 44, a GUI (Graphical User Interface) for accepting various operations from the operator, and the like. For example, the display 42 is a liquid crystal display or a CRT (Cathode Ray Tube) display. Also, the display 42 is an example of a display unit. Also, the display 42 may be provided on the gantry device 10 . The display 42 may be of a desktop type, or may be configured by a tablet terminal or the like capable of wireless communication with the main body of the console device 40 .

The input interface 43 receives various input operations from the operator, converts the received input operations into electrical signals, and outputs the electrical signals to the processing circuit 44 . For example, the input interface 43 receives acquisition conditions for acquiring projection data, reconstruction conditions for reconstructing CT images, image processing conditions for generating post-processed images from CT images, and the like from the operator. . For example, the input interface 43 is implemented by a mouse, keyboard, trackball, switch, button, joystick, or the like. Also, the input interface 43 is part of the input section. Also, the input interface 43 may be provided in the gantry device 10 . Also, the input interface 43 may be composed of a tablet terminal or the like capable of wireless communication with the main body of the console device 40 .

The processing circuit 44 controls the operation of the entire X-ray CT apparatus 1 according to the electric signal of the input operation output from the input interface 43 . For example, the processing circuit 44 has, as hardware resources, processors such as a CPU, MPU, and GPU (Graphics Processing Unit), and memories such as a ROM and a RAM. The processing circuit 44 executes a system control function 441, an image generation function 442, an estimation function 443, a scan control function 444, a display control function 445, etc. by means of a processor that executes programs developed in memory.

The system control function 441 controls each function of the processing circuit 44 based on input operations received from the operator via the input interface 43 . Specifically, the system control function 441 reads the control program stored in the memory 41, develops it on the memory in the processing circuit 44, and controls each part of the X-ray CT apparatus 1 according to the developed control program. .

The image generation function 442 generates data by performing preprocessing such as logarithmic conversion processing, offset correction processing, inter-channel sensitivity correction processing, and beam hardening correction on the detection data output from the DAS 18 . Data before preprocessing (detection data) and data after preprocessing may be collectively referred to as projection data. Further, the image generation function 442 performs reconstruction processing using a filtered back projection method, an iterative reconstruction method, or the like on such projection data to generate CT image data. When reconstructing CT image data, the full-scan reconstruction method requires projection data for 360° around the subject, and the half-scan reconstruction method also requires projection data for 180° + fan angle. be. This embodiment can be applied to any reconstruction method. In the following, for the sake of simplicity, a reconstruction (full-scan reconstruction) method for reconstruction using projection data for 360 degrees around the object will be used. The CT image data represents the spatial distribution of CT values for the subject P. FIG. The CT value is a value for expressing a CT image, and refers to a relative value defined as 0 for water and -1000 for air. The CT value is determined by the X-ray attenuation coefficient, and calibration is performed so that the X-ray attenuation coefficient μ_water of water is 0 and the X-ray attenuation coefficient μ_air of air is −1000. Therefore, a tissue having a higher X-ray attenuation coefficient than water has a higher CT value. When the X-ray attenuation coefficient of tissue is μ, the CT value [HU] of tissue is obtained from the following equation.
CT value of tissue [HU] = 1000 x (μ-μ_water)/μ_water
The image generation function 442 converts generated CT image data into tomographic image data or volume data of an arbitrary cross section by a known method based on an input operation received from an operator via the input interface 43 . Volume data is data having CT value distribution information in a three-dimensional space. The converted tomographic image data and volume data are displayed on the display 42 as monitoring images and volume images, for example. A monitoring image is a tomographic image at the time of monitoring imaging. As known methods, for example, three-dimensional image processing such as volume rendering, surface rendering, image value projection processing, MPR (Multi-Planer Reconstruction) processing, CPR (Curved MPR) processing, etc. can be used as appropriate. .

Estimating function 443 includes a first estimating function and a second estimating function.
The first estimating function estimates the stationary phase of the subject's P heart from a plurality of pieces of medical image data in the memory 41 . The first estimating function is an example of a first estimating section.

The second estimation function estimates the timing of the stationary phase at the time when the index value of the concentration of the contrast agent in the pixels of the region of interest of each of the plurality of medical image data is equal to or greater than a threshold. Here, for example, when the index value reaches the threshold value, the second estimation function estimates the timing of the first stationary phase from the time when the index value reaches the threshold value. Note that the second estimation function is not limited to this, and estimates the timing at which the index value exceeds the threshold value before the index value reaches the threshold value, and estimates the timing of the first stationary phase from the estimated timing. You may do so. The second estimating function is an example of a second estimating section.

The scan control function 444 acquires positioning image data of the subject P for determining the scan range, region of interest, imaging conditions, and the like. The imaging conditions include, for example, the tube voltage/tube current of the X-ray tube 11, the bed movement amount (imaging pitch) in one rotation with respect to the total width of the obtained image slice, the start timing, the number of imaging rows, the rotation speed, and the like. .

The scan control function 444 controls the imaging system so as to sequentially execute monitoring imaging and main scanning. In this embodiment, the scan control function 444 controls the imaging system to execute the main scan based on the timing estimated by the estimation function 443 .

Here, monitoring imaging is imaging in which a region of interest (ROI) is set on a monitoring image, which is a tomographic image of a subject, and changes in contrast agent concentration in the region of interest are observed. Monitoring imaging is imaging for determining whether or not the contrast agent has reached a target concentration. Monitoring radiography does not directly contribute to diagnosis, but is an imaging method necessary for obtaining an appropriate contrast-enhanced image, and is used in most cases of cardiac radiography. Monitoring imaging is not limited to continuous exposure, and intermittent exposure may be performed from the viewpoint of reducing exposure. In the case of continuous irradiation, data for one heartbeat can be acquired if there is continuous data for about two seconds. In addition to this, the accuracy of heart rate estimation can be ensured until the arrival of the contrast medium. Even in the case of intermittent irradiation, it is possible to roughly estimate the cardiac phase from the difference between the obtained images and the motion of the image during one scan. Conversely, the intermittent timing may be controlled based on the cardiac phase estimation result. Here, the term "cardiac phase" usually refers to the R wave detected by the electrocardiogram signal, normalizes the time from the R wave to the R wave by 100%, and expresses the time of the current frame in %. It refers to what is done. For example, the cardiac phase at end-systole is around 25%. Since the present embodiment does not use an electrocardiograph, the R wave cannot be obtained, and therefore, a meaningful cardiac phase based on the R wave cannot be obtained. However, in the present embodiment, for example, the waveform characteristics of the motion graph are used as markers, and the cycle from one marker to the next is normalized by 100%, thereby making it possible to roughly estimate the cardiac phase. The same applies to stationary phases in cardiac phases, and for example, areas of a motion graph with small motion can be estimated as stationary phases. In other words, the cardiac phase and stationary phase referred to in this embodiment refer to the cardiac phase and stationary phase estimated from the waveform of the motion graph. This also applies to other embodiments. Note that "monitoring imaging" is also referred to as "monitoring scanning". The scan control function 444 is an example of a control unit.

The display control function 445 controls the display 42 to display data such as processing results by each function. For example, the display control function 445 causes the display 42 to display a medical image based on medical image data. The display control function 445 is an example of a display control unit.

Note that the system control function 441, the image generation function 442, the estimation function 443, the scan control function 444, and the display control function 445 may be implemented by the processing circuit 44 of one substrate, or may be implemented by the processing circuits 44 of a plurality of substrates. It may be implemented in a distributed manner. Similarly, although console device 40 has been described as performing multiple functions with a single console, multiple functions may be performed by separate consoles.

The communication interface 45 is a circuit for communicating with an external device by wire, radio, or both. The external device is the injector 50 in this example, but is not limited to this. External devices include, for example, modality, image processing device, radiology department information management system (RIS: Radiological Information System), hospital information system (HIS: Hospital Information System) and PACS (Picture Archiving and Communication System), etc. It may be a server, or another workstation or the like.
The injector 50 injects the contrast medium into the subject P according to the injection amount and injection speed communicated from the scan control function 444 .

Next, the operation of the X-ray CT apparatus configured as described above will be described with reference to the flow chart of FIG. 2 and the schematic diagram of FIG.

First, the X-ray CT apparatus 1 acquires subject information (patient information) regarding a subject to be examined from an examination reservation system or the like via a communication interface (not shown). The subject information includes patient ID, patient name, date of birth, age, weight, sex, and examination site. The subject information may include implant information indicating the subject's implant.

Subsequently, the imaging setup of step ST1 is executed. In the X-ray CT apparatus 1, after the subject P is placed on the top plate 33 by the operator, the injector 50 is inserted into the vein of the right arm of the subject P as shown in FIG. . Note that contrast setup may be performed after positioning imaging.

After step ST1, in step ST2, the scan control function 444 sets an imaging plan including imaging conditions for positioning imaging according to the operation of the input interface 43 by the operator.

After step ST2, in step ST3, the scan control function 444 acquires positioning image data of the subject P for determining the scan range, region of interest, imaging conditions, and the like.

For example, when acquiring positioning image data, projection data for the entire circumference of the subject P is acquired by helical scanning or non-helical scanning. Here, the scan control function 444 executes a helical scan or a non-helical scan over a wide range such as the whole chest including the heart of the subject P with a dose lower than that of the main scan. As the non-helical scan, for example, a step-and-shoot method is executed in which scanning is performed while the top plate 33 is stopped each time the position of the top plate 33 is moved at regular intervals.

In this way, the scan control function 444 collects detection data for the entire circumference of the subject, so that the image generation function 442 can reconstruct three-dimensional X-ray CT image data (volume data). Two-dimensional positioning image data corresponding to an arbitrary direction may be generated based on the reconstructed volume data. The positioning image data can also be treated as three-dimensional positioning image data by using the volume data described above.

After step ST3 is completed, in step ST4, the scan control function 444 sets monitoring conditions for performing monitoring imaging of the subject P according to the operation of the input interface 43 by the operator. Monitoring conditions include imaging conditions and imaging conditions. Contrast conditions include, for example, the injection speed, injection amount, and injection time of the contrast agent. Further, the scan control function 444 sets a region of interest for monitoring imaging on the positioning image by the operation of the input interface 43 by the operator.

After step ST4, monitoring photography is performed in step ST5. At this time, the scan control function 444 controls the injector 50 that injects the contrast medium into the subject P based on the contrast conditions. Also, the scan control function 444 controls the X-ray source and the X-ray detector 12 to perform monitoring imaging based on imaging conditions.

During monitoring imaging, the image generation function 442 performs reconstruction processing on projection data output from the X-ray detector 12 via the DAS 18, and sequentially generates a plurality of medical image data (monitoring image data). Save in memory 41 . The estimating function 443 calculates heartbeat timings corresponding to characteristic motions from the plurality of medical image data in the memory 41 (step ST6), and estimates the stationary phase with the small heart motion among the cardiac phases between the heartbeat timings. do. In step ST6, for example, based on a plurality of pieces of medical image data, a motion graph is created that represents the magnitude of the motion of the heart in chronological order, and the heartbeat timing is calculated based on the time intervals of characteristic motions in the motion graph. to calculate It also estimates the stationary phase based on regions of low motion in the motion graph.

After step ST6, the scan control function 444 determines whether or not the index value of the concentration of the contrast agent in the pixels of the region of interest ROI of the medical image data has reached the threshold value (step ST7). This determination is performed, for example, by creating a time density curve (TDC) representing the CT values (index values) of pixels in the region of interest ROI in time series and comparing the CT values with a threshold value. It should be noted that the determination in step ST7 does not necessarily need to create a TDC, and can be performed by comparing the index value and the threshold value. If the result of determination in step ST7 is NO, steps ST5 and ST6 are continuously executed.

On the other hand, when the CT value reaches the threshold, the scan control function 444 determines that the contrast enhancement condition is suitable for the main scan, and terminates the monitoring imaging. Further, when the CT value reaches the threshold value, the estimation function 443 estimates the timing of the first stationary phase from the time of the arrival (step ST8). That is, the estimation function 443 estimates the timing of the static phase when the CT value is equal to or greater than the threshold.

After step ST8, in step ST9, the scan control function 444 controls the X-ray source and the X-ray detector 12 to execute the main scan based on the estimated timing. This main scan is, for example, a volume scan capable of imaging the entire heart in one rotation scan.

During the main scan, the image generation function 442 performs reconstruction processing on the projection data output from the X-ray detector 12 via the DAS 18, generates medical image data (tomographic image data and volume data), and stores them in memory. Save to 41. Note that volume data is generated by interpolating a plurality of reconstructed tomogram data.

The scan control function 444 determines whether or not the cardiac phase of the medical image data (tomographic image data) obtained in the main scan is the stationary phase (step ST10). It controls the X-ray source and the X-ray detector 12 . This completes the main scan. On the other hand, if the result of determination in step ST10 is NO, the scan control function 444 continues the process of step ST10.

As described above, according to the first embodiment, a plurality of pieces of medical image data captured over time while a contrast medium is being injected into a subject are stored. A stationary phase of the subject's heart is estimated from a plurality of pieces of medical image data. The timing of the stationary phase is estimated at the time when the index value of the concentration of the contrast medium in the pixels of the region of interest of each of the plurality of medical image data is equal to or greater than the threshold. Based on the timing, the imaging system is controlled to execute the main scan.

In this way, the workflow of CT imaging for blood vessel observation can be improved by omitting the work of attaching an electrocardiograph when injecting a contrast medium and capturing medical image data of the heart in the stationary phase. can. The improved workflow is a workflow for performing preparations, settings, etc., similar to those for normal asynchronous contrast-enhanced imaging. In the improved workflow, the static phase timing is estimated from the monitoring image, so there is no need to set detailed conditions regarding the imaging timing, and the burden on the user is reduced.

Specifically, without using an electrocardiograph or an additional device to replace the electrocardiograph, the heartbeat timing is calculated using a monitoring image with a contrast agent. Also, the arrival of the contrast medium is measured from the monitoring image, and the timing of the next stationary phase is estimated. Therefore, even without using an electrocardiograph, it is possible to perform CT imaging of the heart in the static phase state with high contrast due to the contrast medium, as in the case of using an electrocardiograph. In addition, the timing of imaging is not affected by the accuracy of the electrocardiograph, and errors due to the electrocardiograph, such as noise and skipping of R waves, do not occur.

Further, in the conventional coronary artery CTA, when the CT value reaches the threshold value in the monitoring imaging, the main scan is executed based on the next R wave, so there is a time lag of at least about 1 second.

On the other hand, according to the present embodiment, when the index value reaches the threshold value, the timing of the first stationary phase is estimated from the time when the index value reaches the threshold value. Main scan can be executed. Therefore, the occurrence of time lag can be prevented.

In addition, according to the present embodiment, since the monitoring imaging and the heart rate estimation are performed in parallel, the exposure dose is not increased more than that of the normal contrast imaging examination. As a comparative example, in addition to monitoring imaging, preparatory imaging with a lower dose than the main scan is performed, and heartbeat estimation is performed based on the obtained heart image. turn into.

<Modification>
Next, a modified example of the first embodiment will be described.

The modification modifies the configuration of the second estimation function in the estimation function 443 from the viewpoint of reducing the exposure dose compared to the first embodiment. Specifically, the second estimation function according to the modification estimates the timing at which the index value of the concentration of the contrast agent exceeds the threshold before the index value reaches the threshold, and the first stationary state from the estimated timing. Estimate phase timing.

The configuration of other parts is the same as that of the first embodiment.

Next, the operation of the modified example of the X-ray CT apparatus configured as described above will be described with reference to the flow chart of FIG. 4 and the schematic diagram of FIG. The operation of this modification is to perform steps ST7A and ST8A as shown in FIG. 4 instead of steps ST7 and ST8 in FIG.

That is, the X-ray CT apparatus 1 executes steps ST1 to ST6 in the same manner as described above, calculates the heartbeat timing, and estimates the stationary phase.

After step ST6, the estimation function 443 determines the timing at which the index value of the concentration of the contrast agent in the pixels of the region of interest ROI of the medical image data exceeds the threshold before the index value reaches the threshold, as shown in FIG. It is determined whether or not t_th has been estimated (step ST7A). This determination is performed, for example, based on the CT value, which is an index value, the slope of the CT value on TDC, and the threshold. Specifically, for example, the timing t_th is not estimated when the difference between the CT value and the threshold is large, and the timing t_th is estimated when the difference between the CT value and the threshold is small. When estimating the timing t_th, for example, the slope of the current CT value may be extrapolated to obtain the timing t_th exceeding the threshold. Note that when the difference between the CT value and the threshold is large, the timing t_th can be estimated, but if the slope of the CT value changes midway, the error of the estimated timing t_th increases. For this reason, the operation of not estimating the timing t_th when the difference between the CT value and the threshold is large has been described, but the present embodiment is not limited to this. If the result of determination in step ST7A is NO (time t1), steps ST5 and ST6 are continuously executed.

On the other hand, when estimating the timing t_th at which the CT value exceeds the threshold (time t2), the estimation function 443 controls the scan control function 444 to end the monitoring imaging. For ease of understanding, the motion graph shown in FIG. 5 also includes periods (periods in which the motion graph cannot be drawn) excluding monitoring imaging and main scanning. The estimation function 443 also estimates the timing t_ph of the first stationary phase from the timing t_th at which the CT value exceeds the threshold (step ST8A). For example, as shown in FIG. 5, the heartbeat period is Tb, and the cardiac phase of timing t_ph of the stationary phase is 80%. From the motion graph, the timing t_0 at which the cardiac phase is 0%, which is closest to the current time t2, is obtained. The time from the timing t_0 to the timing t_th when the threshold value is exceeded (t_th−t_0) is divided by the heartbeat period Tb and multiplied by 100. As a result, the cardiac phase p_th={(t_th−t_0)/Tb}×100(%) at the timing t_th exceeding the threshold is obtained. For example, suppose p_th is obtained as 30%.

Therefore, since the timing t_ph of the first stationary phase from the timing t_th exceeding the threshold is 80%−30%=50%, the time of 50% of the heartbeat cycle Tb is added to the timing t_th exceeding the threshold. be done. That is, the stationary phase timing t_ph is obtained, for example, as shown in the following equation.

t_ph = (0.8-p_th) Tb + t_th
After step ST8A, the X-ray CT apparatus 1 performs steps ST9 to ST10 in the same manner as described above, and the main scan ends.

According to the modified example described above, the timing at which the index value exceeds the threshold value is estimated before the index value reaches the threshold value, and the timing of the first stationary phase is estimated from the estimated timing. As a result, monitoring imaging can be completed before the index value reaches the threshold value, and the state can shift to the imaging standby state for the main scan. , and the timing t_th exceeding the threshold can be reduced.

<Second embodiment>
Next, an X-ray CT apparatus according to a second embodiment will be described with reference to schematic diagrams of FIGS. 6 to 9. FIG.
The second embodiment is a specific example of the first embodiment, and shows various examples of the first estimation function in the estimation function 443 of the processing circuit 44. FIG. That is, when the first estimation function estimates the stationary phase, for example, (a) a method using inter-frame differences, (b) a method using pattern matching, and (c) a method using optical flow can be used as appropriate. It's becoming Specifically, as shown in FIG. 6, when a motion graph showing the motion of the heart in time series is created from a plurality of medical image data, which are monitoring images, and the stationary phase is estimated from the motion graph, the above method (a ) to (c) can be used as appropriate. The pattern of the monitoring image shown in FIG. 6 schematically shows that the heart is beating, and differs from the pattern of the actual monitoring image. The pattern of the actual monitoring image is the pattern of the axial image similar to the monitoring image shown in FIG. The pattern of the image is the same in other drawings.

Here, the case of using the inter-frame difference of (a) will be described. In this case, the first estimating function, in the configuration described above, calculates difference time-series data by taking information differences between a plurality of pieces of medical image data, and calculates the stationary phase based on the difference time-series data. presume. Specifically, as shown in FIG. 7, the first estimating function obtains the information difference between the monitoring images i1 and i2 that are continuous along the time series, calculates the heartbeat variation information (heartbeat timing), A stationary phase within one heartbeat is estimated based on the pulsatile variability information. The difference in information may be the difference in CT values between regions other than the region of interest in the monitoring image, and the pulsatility variation information may be time-series data of the difference in CT values. Alternatively, the information difference may be the difference between the histograms h1 and h2 between the regions other than the region of interest of the monitoring images i1 and i2, and the pulsation fluctuation information may be time-series data of the difference between the histograms h1 and h2. good too. The histograms h1 and h2 have the frequency on the vertical axis and the CT value on the horizontal axis. The reason why the difference between regions other than the region of interest is taken is that the CT value of the region of interest is more influenced by the concentration of the contrast agent than by the movement of the heart. Further, image processing such as edge enhancement may be performed on the monitoring images i1 and i2 before obtaining the difference between the CT values or the histograms h1 and h2.

Next, the case of using pattern matching in (b) will be described. In this case, the first estimation function performs pattern matching on each of the plurality of pieces of medical image data in the configuration described above to calculate the amount of movement of the pattern in the plurality of pieces of medical image data, and calculates the amount of movement of the pattern. Estimate the stationary phase based on Specifically, as shown in FIG. 8, the first estimation function sets a predetermined portion in the monitoring image as a pattern pt for tracking, and tracks the position of the pattern pt for each of the monitoring images i1, i2, . , the heartbeat timing is calculated based on the change in the position of the pattern pt. A stationary phase within one heartbeat is estimated based on the calculated heartbeat timing. Tracking patterns may be set manually or automatically determined by the system.

Finally, the case of using the optical flow of (c) will be described. In this case, the first estimation function, in the configuration described above, calculates a motion vector between a plurality of pieces of medical image data, and estimates the stationary phase based on the motion vector. Specifically, as shown in FIG. 9, the first estimation function calculates a motion vector for continuous monitoring images i1 and i2 along the time series, and according to changes in absolute values of the motion vectors, , to calculate the heartbeat timing. A stationary phase within one heartbeat is estimated based on the calculated heartbeat timing. Note that the heartbeat timing may be calculated based on at least part of the calculated motion vectors.

The configuration of other parts is the same as that of the first embodiment.
According to the second embodiment having the configuration as described above, when the inter-frame difference is used in step ST6 described above, the time-series data of the difference is obtained by taking the information difference between a plurality of pieces of medical image data. Then, the stationary phase is estimated based on the time-series data of the difference.

Alternatively, in step ST6, when pattern matching is used, by performing pattern matching on each of the plurality of medical image data, the amount of movement of the pattern in the plurality of medical image data is calculated, and based on the amount of movement of the pattern Estimate the stationary phase.

Alternatively, in step ST6, when optical flow is used, a motion vector between a plurality of pieces of medical image data is calculated, and the static phase is estimated based on the motion vector.

Therefore, by using a configuration using information difference, pattern matching, motion vector, or the like, it is possible to estimate the stationary phase by various methods in addition to the same effects as those of the first embodiment or its modification.

<Third Embodiment>
Next, an X-ray CT apparatus according to the third embodiment will be explained.
The third embodiment is a specific example of the first or second embodiment, and in step ST10 for judging the end of the main scan, it is judged whether or not the cardiac phase of the CT image taken in the main scan is the stationary phase. It shows an example for

Along with this, in addition to the configuration described above, the memory 41 stores each piece of medical image data for one heart beat among the plurality of pieces of medical image data in association with the cardiac phase of the heart. For example, the memory 41 records a medical image file having medical image data and additional information associated with each other as a file in a data format conforming to the DICOM (Digital Imaging and Communications in Medicine) standard. Here, by including the cardiac phase in the incidental information of the medical image data, the medical image data is stored in association with the cardiac phase. Further, each piece of medical image data for one heartbeat is each piece of monitoring image data obtained during monitoring imaging. A set of each medical image data for one heartbeat may be called a list. This list may be given an arbitrary name such as a cardiac phase correspondence list or a monitoring image list.

In addition to the configuration described above, the scan control function 444 compares the medical image data obtained during execution of the main scan with the medical image data stored in association with the stationary phase of the cardiac phase, and outputs the comparison result. is within the allowable range, the imaging system is controlled to end the main scan. Specifically, the medical image data stored in association with the target phase among the static phases is used for comparison. Further, when the comparison result is out of the allowable range, the photographing system is controlled so as to continue the main scan if the photographing time of the main scan is within the allowable time, and to end the main scan if it is outside the allowable time.

The configuration of other parts is the same as in the first or second embodiment.
Next, the operation of the X-ray CT apparatus configured as described above will be described with reference to the flow chart of FIG. 10 and the schematic diagrams of FIGS. This operation performs steps ST10-1 to ST10-5 in step ST10 of FIG. 2 or FIG.

That is, the X-ray CT apparatus 1 performs steps ST1 to ST9 and performs the main scan in the same manner as described above. However, after calculating the heartbeat timing and estimating the stationary phase in step ST6, the estimating function 443 associates each piece of medical image data for one heartbeat of the subject P with the cardiac phase of the heart and stores it in the memory 41. write to

Further, during the main scan in step ST9, the image generation function 442 generates medical image data and stores it in the memory 41 as described above.

As shown in FIG. 11, the scan control function 444 associates the medical image data (real-time image data) obtained during execution of the main scan with the stationary phase (the target phase within) of the cardiac phase. It compares with the stored medical image data (step ST10-1). The scan control function 444 determines whether or not this comparison result is within the allowable range (step ST10-2). It controls the detector 12 . This completes the main scan. In the example shown in FIG. 11, the exposure area EM1 corresponds to a stationary phase with a small value in the motion graph.

On the other hand, if the determination result in step ST10-2 is negative, the scan control function 444 calculates the time until the target phase (step ST10-3). For example, the memory 41 is searched for a monitoring image that matches the real-time image within an allowable range, and the time to the target phase is calculated based on the difference between the cardiac phase of the monitoring image and the cardiac phase of the monitoring image of the target phase. do. For example, assume that the monitoring image that matches the real-time image within an acceptable range has a cardiac phase p_rt of 40%, and the target phase monitoring image p_tg has a cardiac phase of 80%. At this time, by converting the difference between the two cardiac phases into time using the heartbeat cycle Tb, the time to the target phase is (p_tg−P_rt)×Tb=(0.8−0.4)Tb=0.4Tb calculated as

The scan control function 444 determines whether or not the extended imaging time obtained by extending the time up to the target phase is within the allowable time (step ST10-4). end the main scan. That is, when the extended shooting time is too long, the shooting ends for safety.

On the other hand, if the result of determination in step ST10-4 is that the extended imaging time is within the allowable time, the scan control function 444 continues imaging for the main scan (step ST10-5) and returns to step ST10-1. . After that, as shown in FIG. 12, for example, after steps ST10-1 and ST10-2 again, the comparison result is within the allowable range, and the main scan ends. In the example shown in FIG. 12, the exposure area EM2 corresponding to the extended imaging time corresponds to the static phase with a small motion graph value.

As described above, according to the third embodiment, among a plurality of pieces of medical image data, each piece of medical image data for one heart beat is stored in association with the cardiac phase of the heart. The medical image data obtained during the execution of the main scan is compared with the medical image data stored in association with the stationary phase of the cardiac phase, and when the comparison result is within the allowable range, the main scan is performed. Control the imaging system to finish. Thereby, in addition to the effect of the first or second embodiment, it is possible to determine that the cardiac phase of the medical image data captured in the main scan is the stationary phase, and reduce the possibility of imaging failure.

Specifically, at the time of the main scan, a list corresponding to the cardiac phases from the monitoring images is maintained, and the monitoring image of the target phase at the rest phase in the list is compared with the real-time image of the main scan. Finish the main scan. When a deviation from the target phase is detected at the timing of the real-time image of the main scan, the imaging time is extended to reduce the possibility of re-inspection. Alternatively, a longer imaging time may be set in advance at the timing of imaging the main scan, and the imaging may be interrupted when normal, or the imaging time may be extended when a deviation occurs in the cardiac phase. Any of the methods (a) to (c) in the second embodiment may be used as the method for detecting a cardiac phase shift.

Note that, unlike the third embodiment, when an electrocardiograph is worn, if atrial fibrillation (AF) occurs, the RR interval becomes longer, so the imaging time is extended. It will be done. In contrast, according to the third embodiment, even if atrial fibrillation occurs, if it can be determined that the real-time image of the main scan was taken in the stationary phase, the main scan can be terminated. .

<Modification 1>
Next, Modification 1 of the third embodiment will be described with reference to FIG.
Compared to the third embodiment, Modification 1 uses the inter-frame difference in step ST10A instead of step ST10 in order to omit the list of monitoring images.

Along with this, the memory 41 has the same configuration as in the first embodiment.

In addition to the configuration of the first embodiment, the scan control function 444 uses the inter-frame difference to determine whether or not the phase is stationary, and terminates the main scan when the determination result indicates the stationary phase. Specifically, the scan control function 444 calculates difference time-series data by taking information differences between a plurality of pieces of medical image data obtained during execution of the main scan, and calculates time-series data of the differences. Determine the stationary phase based on .

The configuration of other parts is the same as that of the first embodiment.

According to the modified example 1 having the configuration as described above, after steps ST1 to ST9 are executed in the same manner as described above, the scan control function 444 executes step ST10A instead of step ST10. In step ST10A, the scan control function 444 calculates information differences between a plurality of pieces of medical image (real-time image) data obtained during execution of the main scan (step ST10A-1). The difference in information may be the difference in CT values or the difference in histograms, as described above.

After step ST10A-1, the scan control function 444 determines whether or not the calculated difference is smaller than the reference value (step ST10A-2), and if not, returns to step ST10A-1. If the result of determination in step ST10A-2 is that the difference is smaller than the reference value, the scan control function 444 determines whether or not the small difference has continued for a certain period of time (step ST10A-3). If the result of determination in step ST10A-3 is NO, the process returns to step ST10A-1. By continuing steps ST10A-1 and ST10A-2, if the determination result of step ST10A-3 indicates that a small difference has continued for a certain period of time, the scan control function 444 instructs the imaging system to end the main scan. to control. This completes the main scan.

According to Modification 1 as described above, difference time-series data is calculated by taking information differences between a plurality of pieces of medical image data obtained during execution of the main scan, and time-series data of the differences are calculated. Determine the stationary phase based on . When the determination result indicates the stationary phase, the imaging system is controlled so as to end the main scan. Therefore, without using the list of monitoring images in the third embodiment, as in the third embodiment, it is determined that the cardiac phase of the medical image data captured in the main scan is the stationary phase, and the imaging failure is detected. Possibility can be reduced.

Modification 1 may be applied not only to the first embodiment but also to the second embodiment.

<Modification 2>
Next, Modification 2 of the third embodiment will be described with reference to FIG.
Compared to the third embodiment, Modified Example 1 uses an inter-frame difference in step ST10B instead of step ST10 in order to omit calculations related to the extended shooting time. Note that the calculation regarding the extended imaging time here corresponds to steps ST10-3 to ST10-5.

Along with this, the memory 41 has a configuration similar to that of the third embodiment.

In addition to the configuration of the third embodiment, the scan control function 444 uses the inter-frame difference to determine whether or not the phase is stationary instead of performing the processing of steps ST10-3 to ST10-5. is shown, the main scan is terminated. Specifically, the scan control function 444 calculates difference time-series data by taking information differences between a plurality of pieces of medical image data obtained during execution of the main scan, and calculates time-series data of the differences. Determine the stationary phase based on .

The configuration of other parts is the same as that of the third embodiment.

According to the modified example 2 having the configuration as described above, after steps ST1 to ST9 are executed in the same manner as described above, the scan control function 444 executes step ST10B instead of step ST10. In step ST10B, the scan control function 444 executes steps ST10B-1 to ST10B-2 for comparing the list of monitoring images and the real-time images, similarly to steps ST10-1 to ST10-2 of the third embodiment. . If the determination result of step ST10B-2 is negative, the scan control function 444 executes steps ST10B-3 to ST10B-5 using the inter-frame difference in the same way as steps ST10A-1 to ST10A-3 of Modification 1. do. Note that step ST10B-3 is processing that is shifted to when the real-time image is not in the static phase as a result of the determination in step ST10B-2. Therefore, steps ST10B-3 to ST10B-5 are repeatedly executed until the real-time image corresponds to the stationary phase. If the result of determination in step ST10B-5 is that a small difference has continued for a certain period of time, the main scan ends in the same manner as described above.

According to Modified Example 2 as described above, each piece of medical image data for one heart beat among a plurality of pieces of medical image data is stored in association with the cardiac phase of the heart. The medical image data obtained during the execution of the main scan is compared with the medical image data stored in association with the stationary phase of the cardiac phase, and when the comparison result is within the allowable range, the main scan is performed. Control the imaging system to finish. On the other hand, when the comparison result is outside the allowable range, the time-series data of the difference is calculated by taking the information difference between the multiple pieces of medical image data obtained during the execution of the main scan, and the time-series data of the difference is calculated. A stationary phase is determined based on the data. When the determination result indicates the stationary phase, the imaging system is controlled so as to end the main scan. Therefore, while omitting the calculation related to the extended imaging time in the third embodiment, as in the third embodiment, it is determined that the cardiac phase of the medical image data captured in the main scan is the stationary phase, and imaging fails. can reduce the possibility of

Modification 2 may be applied not only to the first embodiment but also to the second embodiment.

According to at least one embodiment described above, a plurality of pieces of medical image data captured over time while a contrast agent is being injected into a subject are stored. A stationary phase of the subject's heart is estimated from a plurality of pieces of medical image data. The timing of the stationary phase is estimated at the time when the index value of the concentration of the contrast medium in the pixels of the region of interest of each of the plurality of medical image data is equal to or greater than the threshold. Based on the timing, the imaging system is controlled to execute the main scan.

In this way, the workflow of CT imaging for blood vessel observation can be improved by omitting the work of attaching an electrocardiograph when injecting a contrast medium and capturing medical image data of the heart in the stationary phase. can.

The term "processor" used in the above description means a circuit such as, for example, a CPU, a GPU, or an application specific integrated circuit (ASIC), programmable logic device, or the like. Programmable logic devices include, for example, Simple Programmable Logic Devices (SPLDs), Complex Programmable Logic Devices (CPLDs), and Field Programmable Gate Arrays (FPGAs). "CPU" is an abbreviation for "Central Processing Unit." "GPU" is an abbreviation for "Graphics Processing Unit." "ASIC" is an abbreviation for Application Specific Integrated Circuit. "SPLD" is an abbreviation for "Simple Programmable Logic Device". "CPLD" is an abbreviation for "Complex Programmable Logic Device". "FPGA" is an abbreviation for "Field Programmable Gate Array". This type of processor achieves its functions by reading and executing programs stored in memory. It should be noted that instead of storing the program in the memory, the program may be directly embedded in the circuit of the processor. In this case, the processor implements its functions by reading and executing the program embedded in the circuit. Note that each processor of the present embodiment is not limited to being configured as a single circuit for each processor, and may be configured as one processor by combining a plurality of independent circuits to realize its function. good. Furthermore, a plurality of components in FIG. 1 may be integrated into one processor to realize its functions.

It should be noted that although several embodiments of the invention have been described, these embodiments are provided by way of example 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 modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

Reference Signs List 1 X-ray CT apparatus 10 Mounting device 11 X-ray tube 12 X-ray detector 13 Rotating frame 14 X-ray high voltage device 15 Control device 16 Wedge 17 Collimator 18 DAS
19 FOVs
30 bed device 31 base 32 bed drive device 33 top plate 34 support frame 40 console device 41 memory 42 display 43 input interface 44 processing circuit 441 system control function 442 image generation function 443 estimation function 444 scan control function 445 display control function 50 injector P Subject

Claims (8)

a memory for storing a plurality of medical image data captured over time while a contrast agent is injected into the subject;
a first estimating unit that estimates a stationary phase of the heart of the subject from the plurality of medical image data;
a second estimation unit for estimating the timing of the stationary phase at a time when the index value of the concentration of the contrast agent in the pixels of the region of interest of each of the plurality of medical image data is equal to or greater than a threshold;
a control unit that controls the imaging system to perform the main scan based on the timing ,
The X-ray CT apparatus , wherein the first estimator estimates the resting phase of the heart in parallel with capturing the plurality of medical image data for comparing the index value and the threshold value . 2. The X-ray CT apparatus according to claim 1, wherein, when said index value reaches said threshold value, said second estimator estimates the first timing of said stationary phase from the time said reaching said threshold value. The second estimator estimates a timing at which the index value exceeds the threshold before the index value reaches the threshold, and estimates the timing of the first stationary phase from the estimated timing. 2. The X-ray CT apparatus according to 1. wherein the first estimating unit calculates difference time-series data by taking information differences between the plurality of pieces of medical image data, and estimates the stationary phase based on the difference time-series data. 4. The X-ray CT apparatus according to any one of Items 1 to 3. The first estimating unit performs pattern matching on each of the plurality of medical image data to calculate a movement amount of a pattern in the plurality of medical image data, and calculates the movement amount of the pattern in the plurality of medical image data. 4. The X-ray CT apparatus according to any one of claims 1 to 3, which estimates a phase. The X-ray CT according to any one of claims 1 to 3, wherein said first estimator calculates a motion vector between said plurality of pieces of medical image data and estimates said stationary phase based on said motion vector. Device. wherein the memory stores each medical image data for one heartbeat of the heart among the plurality of medical image data in association with a cardiac phase of the heart;
The control unit compares the medical image data obtained during execution of the main scan with the medical image data stored in association with the stationary phase of the cardiac phase, and the comparison result is within an allowable range. 7. The X-ray CT apparatus according to any one of claims 1 to 6, wherein the imaging system is controlled so as to terminate the main scan at certain times. a memory for storing a plurality of medical image data captured over time while a contrast agent is injected into the subject;
a first estimating unit that estimates a stationary phase of the heart of the subject from the plurality of medical image data;
a second estimation unit for estimating the timing of the stationary phase at a time when the index value of the concentration of the contrast agent in the pixels of the region of interest of each of the plurality of medical image data is equal to or greater than a threshold;
a control unit that controls the imaging system to perform the main scan based on the timing;
with
wherein the memory stores each medical image data for one heartbeat of the heart among the plurality of medical image data in association with a cardiac phase of the heart;
The control unit compares the medical image data obtained during execution of the main scan with the medical image data stored in association with the stationary phase of the cardiac phase, and the comparison result is within an allowable range. An X-ray CT apparatus that controls the imaging system to terminate the main scan at certain times.

Images