JP2021013489A - X-ray ct system and medical processing apparatus - Google Patents

Abstract

To improve the realizability of material discrimination by three or more kinds of reference materials.SOLUTION: An X-ray CT system in an embodiment includes a scan unit and a processing unit. The scan unit executes first scan for collecting a first projection data set corresponding to first X-ray energy to a subject, and second scan for collecting a second projection data set corresponding to second X-ray energy different from the first X-ray energy, and a third projection data set corresponding to third X-ray energy different from the first X-ray energy and the second X-ray energy substantially at the same time. The processing unit executes material discrimination by three or more kinds of reference materials on the basis of the first projection data set, the second projection data set, and the third projection data set.SELECTED DRAWING: Figure 3

Description

Embodiments of the present invention relate to X-ray CT systems and medical processing devices.

Based on the projection data corresponding to two or more types of X-ray energies collected by an X-ray CT (Computed Tomography) scanner, there is a technology to discriminate the object by multiple reference substances and display the result as an image. .. When two types of X-ray energy are used, this technique is called dual energy (DE), and it is possible to discriminate substances using two types of reference substances. In this technology, in principle, by increasing the types of X-ray energy used, it is possible to discriminate substances using more types of reference substances.

However, for example, in the kV switching method in which projection data is collected while repeatedly switching the X-ray energy while the X-ray tube makes one revolution around the subject, the X-ray energy frequency increases as the number of types of X-ray energy increases. Since it is necessary to switch the line energy, the energy of the X-ray emitted from the X-ray tube may become unstable. In addition, when the types of X-ray energy are increased by the same method, the amount of projection data (number of views) for each X-ray energy that can be collected while the X-ray tube makes one rotation around the subject is reduced. There is concern that the accuracy of substance discrimination will decrease. Further, when increasing the types of X-ray energy by other methods, a special hardware configuration is required, and there is a concern that the cost will increase.

International Publication No. 2016/147844 Special Table 2015-532140 Japanese Unexamined Patent Publication No. 2014-230707

The problem to be solved by the present invention is to improve the feasibility of substance discrimination based on three or more kinds of reference substances.

The X-ray CT system of the embodiment includes a scanning unit and a processing unit. The scanning unit performs a first scan on the subject to collect a first projection data set corresponding to the first X-ray energy, and a second X-ray energy different from the first X-ray energy. A second projection data set corresponding to the above and a third projection data set corresponding to the first X-ray energy and a third X-ray energy different from the second X-ray energy are collected substantially simultaneously. Perform a second scan. The processing unit discriminates substances with three or more kinds of reference substances based on the first projection data set, the second projection data set, and the third projection data set.

FIG. 1 is a block diagram showing an example of the configuration of the X-ray CT system according to the first embodiment. FIG. 2A is a diagram for explaining the scan and substance discrimination according to the first embodiment. FIG. 2B is a diagram for explaining the scan and substance discrimination according to the first embodiment. FIG. 3 is a diagram for explaining the scan and substance discrimination according to the first embodiment. FIG. 4 is a flowchart for explaining a series of processes of the X-ray CT system according to the first embodiment. FIG. 5 is a diagram for explaining the dual layer type scan according to the second embodiment. FIG. 6 is a block diagram showing an example of the configuration of the medical information processing system 1 according to the fifth embodiment.

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

(First Embodiment)
First, the configuration of the X-ray CT system 10 according to the first embodiment will be described with reference to FIG. FIG. 1 is a block diagram showing an example of the configuration of the X-ray CT system 10 according to the first embodiment. As shown in FIG. 1, the X-ray CT system 10 includes a gantry device 110, a sleeper device 130, and a console device 140. The X-ray CT system 10 is also called an X-ray CT apparatus or an X-ray CT scanner.

In FIG. 1, the rotation axis of the rotation frame 113 in the non-tilt state or the longitudinal direction of the top plate 133 of the sleeper device 130 is the Z-axis direction. Further, the axial direction orthogonal to the Z-axis direction and horizontal to the floor surface is defined as the X-axis direction. Further, the axial direction orthogonal to the Z-axis direction and perpendicular to the floor surface is defined as the Y-axis direction. Note that FIG. 1 is a drawing of the gantry device 110 from a plurality of directions for the sake of explanation, and shows a case where the X-ray CT system 10 has one gantry device 110.

The gantry device 110 includes an X-ray tube 111, an X-ray detector 112, a rotating frame 113, an X-ray high voltage device 114, a control device 115, a wedge 116, a collimator 117, and a DAS 118.

The X-ray tube 111 is a vacuum tube having a cathode (filament) that generates thermoelectrons and an anode (target) that generates X-rays upon collision of thermions. The X-ray tube 111 generates X-rays to irradiate the subject P by irradiating thermions from the cathode toward the anode by applying a high voltage from the X-ray high voltage device 114.

The X-ray detector 112 detects the X-rays irradiated from the X-ray tube 111 and passed through the subject P, and outputs a signal corresponding to the detected X-ray dose to the DAS 118. The X-ray detector 112 has, for example, a plurality of detection element sequences in which a plurality of detection elements are arranged in a channel direction (channel direction) along one arc centered on the focal point of the X-ray tube 111. The X-ray detector 112 has, for example, a structure in which a plurality of detection element sequences in which a plurality of detection elements are arranged in the channel direction are arranged in a row direction (slice direction, row direction).

For example, the X-ray detector 112 is an indirect conversion type detector having a grid, a scintillator array, and an optical sensor array. The scintillator array has a plurality of scintillators. The scintillator has a scintillator crystal that outputs a photon amount of light according to the incident X dose. The grid is arranged on the surface of the scintillator array on the X-ray incident side and has an X-ray shield plate that absorbs scattered X-rays. The grid may also be called a collimator (one-dimensional collimator or two-dimensional collimator). The optical sensor array has a function of converting into an electric signal according to the amount of light from the scintillator, and has, for example, an optical sensor such as a photodiode. The X-ray detector 112 may be a direct conversion type detector having a semiconductor element that converts incident X-rays into an electric signal.

The rotating frame 113 is an annular frame that supports the X-ray tube 111 and the X-ray detector 112 so as to face each other, and rotates the X-ray tube 111 and the X-ray detector 112 by the control device 115. For example, the rotating frame 113 is a casting made of aluminum. In addition to the X-ray tube 111 and the X-ray detector 112, the rotating frame 113 can further support an X-ray high voltage device 114, a wedge 116, a collimator 117, a DAS 118, and the like. Further, the rotating frame 113 can further support various configurations (not shown in FIG. 1). In the following, in the gantry device 110, the rotating frame 113 and the portion that rotates and moves together with the rotating frame 113 are also referred to as a rotating portion.

The X-ray high-voltage device 114 has an electric circuit such as a transformer and a rectifier, and has a high-voltage generator that generates a high voltage applied to the X-ray tube 111 and an X-ray generated by the X-ray tube 111. It has an X-ray control device that controls the output voltage according to the above. The high voltage generator may be a transformer type or an inverter type. The X-ray high voltage device 114 may be provided on the rotating frame 113, or may be provided on a fixed frame (not shown).

The control device 115 includes a processing circuit having a CPU (Central Processing Unit) and the like, and a drive mechanism such as a motor and an actuator. The control device 115 receives the input signal from the input interface 143 and controls the operation of the gantry device 110 and the sleeper device 130. For example, the control device 115 controls the rotation of the rotating frame 113, the tilt of the gantry device 110, the operation of the sleeper device 130, and the like. As an example, the control device 115 rotates the rotating frame 113 about an axis parallel to the X-axis direction based on the input tilt angle (tilt angle) information as a control for tilting the gantry device 110. The control device 115 may be provided in the gantry device 110 or in the console device 140.

The wedge 116 is an X-ray filter for adjusting the X-ray dose emitted from the X-ray tube 111. Specifically, the wedge 116 is an X-ray filter that attenuates the X-rays emitted from the X-ray tube 111 so that the X-rays emitted from the X-ray tube 111 to the subject P have a predetermined distribution. Is. For example, the wedge 116 is a wedge filter or a bow-tie filter, and is manufactured by processing aluminum or the like so as to have a predetermined target angle and a predetermined thickness.

The collimator 117 is a lead plate or the like for narrowing the irradiation range of X-rays transmitted through the wedge 116, and a slit is formed by a combination of a plurality of lead plates or the like. The collimator 117 may be called an X-ray diaphragm. Further, in FIG. 1, the case where the wedge 116 is arranged between the X-ray tube 111 and the collimator 117 is shown, but the case where the collimator 117 is arranged between the X-ray tube 111 and the wedge 116. May be good. In this case, the wedge 116 is irradiated from the X-ray tube 111, and the X-ray whose irradiation range is limited by the collimator 117 is transmitted and attenuated.

The DAS 118 collects X-ray signals detected by each detection element included in the X-ray detector 112. For example, the DAS 118 has an amplifier that amplifies an electric signal output from each detection element and an A / D converter that converts the electric signal into a digital signal, and generates detection data. DAS118 is realized by, for example, a processor.

The data generated by the DAS 118 is transmitted from a transmitter having a light emitting diode (LED) provided on the rotating frame 113 by optical communication to a non-rotating portion (for example, a fixed frame, etc.) of the gantry device 110. Is transmitted to a receiver having a light diode provided in (not shown in the above) and transferred to the console device 140. Here, the non-rotating portion is, for example, a fixed frame that rotatably supports the rotating frame 113. The method of transmitting data from the rotating frame 113 to the non-rotating portion of the gantry device 110 is not limited to optical communication, and any non-contact data transmission method may be adopted, and the contact-type data transmission method may be used. You may adopt it.

The sleeper device 130 is a device for placing and moving the subject P to be scanned, and has a base 131, a sleeper drive device 132, a top plate 133, and a support frame 134. The base 131 is a housing that supports the support frame 134 so as to be movable in the vertical direction. The sleeper drive device 132 is a drive mechanism for moving the top plate 133 on which the subject P is placed in the long axis direction of the top plate 133, and includes a motor, an actuator, and the like. The top plate 133 provided on the upper surface of the support frame 134 is a plate on which the subject P is placed. In addition to the top plate 133, the sleeper drive device 132 may move the support frame 134 in the long axis direction of the top plate 133.

The console device 140 has a memory 141, a display 142, an input interface 143, and a processing circuit 144. Although the console device 140 will be described as a separate body from the gantry device 110, the gantry device 110 may include a part of each component of the console device 140 or the console device 140.

The memory 141 is realized by, for example, a RAM (Random Access Memory), a semiconductor memory element such as a flash memory, a hard disk, an optical disk, or the like. For example, the memory 141 stores various data collected by performing a scan on the subject P. Further, for example, the memory 141 stores a program for the circuit included in the X-ray CT system 10 to realize its function. The memory 141 may be realized by a server group (cloud) connected to the X-ray CT system 10 via a network.

The display 142 displays various information. For example, the display 142 displays an image showing the result of substance discrimination by the processing circuit 144, and displays a GUI (Graphical User Interface) for accepting various operations from the user. For example, the display 142 is a liquid crystal display or a CRT (Cathode Ray Tube) display. The display 142 may be a desktop type, or may be composed of a tablet terminal or the like capable of wireless communication with the console device 140 main body.

The input interface 143 receives various input operations from the user, converts the received input operations into an electric signal, and outputs the received input operations to the processing circuit 144. For example, the input interface 143 receives from the user reconstruction conditions for reconstructing the reconstructed image, image processing conditions for generating a CT image for display from the reconstructed image, and the like. For example, the input interface 143 includes a mouse, a keyboard, a trackball, a switch, a button, a joystick, a touch pad for performing input operations by touching an operation surface, a touch screen in which a display screen and a touch pad are integrated, and an optical sensor. It is realized by the non-contact input circuit, voice input circuit, etc. used. The input interface 143 may be provided on the gantry device 110. Further, the input interface 143 may be composed of a tablet terminal or the like capable of wireless communication with the console device 140 main body. Further, the input interface 143 is not limited to the one provided with physical operating parts such as a mouse and a keyboard. For example, an electric signal processing circuit that receives an electric signal corresponding to an input operation from an external input device provided separately from the console device 140 and outputs the electric signal to the processing circuit 144 is also an example of the input interface 143. included.

The processing circuit 144 controls the operation of the entire X-ray CT system 10 by executing the scanning function 144a, the processing function 144b, and the control function 144c. The scanning function 144a is an example of a scanning unit. The processing function 144b is an example of a processing unit.

For example, the processing circuit 144 executes a scan on the subject P by reading a program corresponding to the scan function 144a from the memory 141 and executing the program. For example, the scan function 144a supplies a high voltage to the X-ray tube 111 by controlling the X-ray high voltage device 114. As a result, the X-ray tube 111 generates X-rays to irradiate the subject P. Further, the scanning function 144a moves the subject P into the photographing port of the gantry device 110 by controlling the sleeper driving device 132. Further, the scanning function 144a controls the distribution of X-rays applied to the subject P by adjusting the position of the wedge 116 and the opening degree and position of the collimator 117. Further, the scan function 144a rotates the rotating portion by controlling the control device 115. Further, while the scan is executed by the scan function 144a, the DAS 118 collects an X-ray signal from each detection element in the X-ray detector 112 and generates detection data. Further, the scan function 144a performs preprocessing on the detection data output from DAS118. For example, the scan function 144a performs preprocessing such as logarithmic conversion processing, offset correction processing, sensitivity correction processing between channels, and beam hardening correction on the detection data output from DAS118. The data after pretreatment is also described as raw data. In addition, the detection data before the pretreatment and the raw data after the pretreatment are collectively referred to as projection data.

Further, the processing circuit 144 generates image data based on the projection data after the preprocessing by reading the program corresponding to the processing function 144b from the memory 141 and executing the program. For example, the processing function 144b generates CT image data by performing reconstruction processing on the projected data using a filter correction back projection method, a successive approximation reconstruction method, or the like. Further, the processing function 144b performs substance discrimination by a plurality of reference substances based on the projection data. The processing function 144b may perform substance discrimination at a stage before the reconstruction process (projection data stage), or at a stage after the reconstruction process (reconstruction image stage). May be done. The discrimination process by the processing function 144b will be described later.

Further, the processing circuit 144 controls the display on the display 142 by reading the program corresponding to the control function 144c from the memory 141 and executing the program. For example, the control function 144c displays a reconstructed image generated by the processing function 144b based on an input operation received from the user via the input interface 143 by a known method as a CT image (fault of an arbitrary cross section). Convert to image data, 3D image data, etc.). Then, the control function 144c causes the converted CT image for display to be displayed on the display 142. Further, for example, the control function 144c causes the display 142 to display an image showing the result of substance discrimination by the processing function 144b. Further, the control function 144c transmits various data via the network. As an example, the control function 144c transmits a reconstructed image generated by the processing function 144b and an image showing the result of substance discrimination to an image storage device (not shown) for storage.

In the X-ray CT system 10 shown in FIG. 1, each processing function is stored in the memory 141 in the form of a program that can be executed by a computer. The processing circuit 144 is a processor that realizes a function corresponding to each program by reading a program from the memory 141 and executing the program. In other words, the processing circuit 144 in the state where the program is read has a function corresponding to the read program.

Although it has been described in FIG. 1 that the scan function 144a, the processing function 144b, and the control function 144c are realized by a single processing circuit 144, the processing circuit 144 is configured by combining a plurality of independent processors. , Each processor may realize the function by executing the program. Further, each processing function of the processing circuit 144 may be appropriately distributed or integrated into a single or a plurality of processing circuits.

Further, the processing circuit 144 may realize the function by utilizing the processor of the external device connected via the network. For example, the processing circuit 144 reads a program corresponding to each function from the memory 141 and executes it, and also uses a server group (cloud) connected to the X-ray CT system 10 via a network as a computational resource. Each function shown in FIG. 1 is realized.

The configuration example of the X-ray CT system 10 has been described above. Hereinafter, the processing performed by the X-ray CT system 10 will be described in detail.

First, an example of substance discrimination will be described with reference to FIGS. 2A and 2B. 2A and 2B are diagrams for explaining the scan and substance discrimination according to the first embodiment. In addition, in FIG. 2A and FIG. 2B, the case where the scan A11 of the kV switching system is executed and the substance is discriminated by three kinds of reference substances will be described as an example. Specifically, the scan function 144a changes the X-ray energy for each view in the six views (view V11, view V12, view V13, view V14, view V15, view V16) shown in FIG. 2A. , The kV switching type scan A11 is executed.

More specifically, the scan function 144a generates X-rays of energy E11 from the X-ray tube 111 in the view V11 by controlling the X-ray high voltage device 114. As a result, the scan function 144a collects the projection data corresponding to the energy E11 in the view V11.

Similarly, the scan function 144a generates X-rays of energy E12 in view V12, X-rays of energy E13 in view V13, X-rays of energy E11 in view V14, and energy E12 in view V15. X-rays are generated and X-rays of energy E13 are generated in view V16. As a result, the scan function 144a collects the projection data corresponding to the energy E12 in the view V12, collects the projection data corresponding to the energy E13 in the view V13, and collects the projection data corresponding to the energy E11 in the view V14. The projection data corresponding to the energy E12 is collected in the view V15, and the projection data corresponding to the energy E13 is collected in the view V16.

Next, the scanning function 144a separates a plurality of projection data collected for each view for each X-ray energy, as shown in FIG. 2B. Specifically, the scan function 144a uses the projection data as the projection data corresponding to the energy E11 (projection data of the view V11 and the view V14) and the projection data corresponding to the energy E12 (projection data of the view V12 and the view V15). And the projection data (projection data of views V13 and view V16) corresponding to the energy E13.

In the following, a plurality of projection data will be collectively referred to as a projection data set. That is, the scan function 144a separates the plurality of projection data collected for each view into a projection data set corresponding to the energy E11, a projection data set corresponding to the energy E12, and a projection data set corresponding to the energy E13. ..

Next, the processing function 144b interpolates the data of the missing portion for each of the three projection data sets shown in FIG. 2B. For example, since the X-rays of the energy E11 are applied to the views V11 and the view V14, the data of the views V12, the view V13, the view V15, and the view V16 are missing from the projection data set corresponding to the energy E11. There is. Therefore, the processing function 144b interpolates the data of the view V12, the view V13, the view V15, and the view V16, which are the missing portions, with respect to the projection data set corresponding to the energy E11. Examples of interpolation processing by the processing function 144b include linear interpolation, Lagrange interpolation, and sigmoid. Further, after interpolating the data of the missing portion, the processing function 144b reconstructs the reconstructed image I11 from the projection data set corresponding to the energy E11.

Similarly, the processing function 144b interpolates the missing portion data for the projection data set corresponding to the energy E12 to reconstruct the reconstructed image I12. Further, the processing function 144b interpolates the data of the missing portion with respect to the projection data set corresponding to the energy E13, and reconstructs the reconstructed image I13.

Next, the processing function 144b discriminates the reconstructed image I11, the reconstructed image I12, and the reconstructed image I13 with three types of reference substances. Examples of the reference substance include water, iodine, calcium, hydroxyapatite, fat, gadolinium and the like. Specifically, the processing function 144b obtains the distribution of the line attenuation coefficient for each of the three reconstructed images, and calculates the mixing amount and mixing ratio of the three reference substances for each pixel of the distribution of the line attenuation coefficient. More specifically, the processing function 144b discriminates substances by solving simultaneous equations shown in the following equation (1) for each pixel in the reconstructed image I11, the reconstructed image I12, and the reconstructed image I13.

Here, "μ (E1)" indicates the line attenuation coefficient of each pixel at the monochromatic X-ray energy "E1", and "μ (E2)" indicates the line attenuation coefficient of each pixel at the monochromatic X-ray energy "E2". , "Μ (E3)" indicate the line attenuation coefficient of each pixel at the monochromatic X-ray energy "E3". In addition, "μ _α (E)" indicates the linear attenuation coefficient of the reference substance α, "μ _β (E)" indicates the linear attenuation coefficient of the reference substance β, and “μ _γ (E)” indicates the linear attenuation coefficient of the reference substance γ. The line attenuation coefficient is shown. Further, "c _α " indicates the mixing amount of the reference substance α, "c _β " indicates the mixing amount of the reference substance β, and “c _γ ” indicates the mixing amount of the reference substance γ. The linear attenuation coefficient for each energy of each reference substance is known. For example, the processing function 144b substitutes energy E11 for "E1", substitutes energy E12 for "E2", and substitutes energy E13 for "E3" to solve the simultaneous equations of equation (1). Material discrimination is performed based on the type of reference substance "α, β, γ".

Then, the processing function 144b generates an image showing the result of substance discrimination. For example, the processing function 144b generates a substance discrimination image for each reference substance. As an example, as shown in FIG. 2B, the processing function 144b has a substance discrimination image in which the reference substance α is emphasized, a substance discrimination image in which the reference substance β is emphasized, and a substance discrimination image in which the reference substance γ is emphasized. Generate each. Further, the control function 144c causes the generated substance discrimination image to be displayed on the display 142.

As described above, by executing the kV switching type scan A11 with three types of X-ray energies, in principle, it is possible to discriminate substances using three types of reference substances. However, as shown in FIG. 2B, the amount of projected data (number of views) for each energy is reduced by switching between the three types of energies. That is, since the amount of data for each energy actually collected is small, there is a concern that the accuracy of substance discrimination may decrease. Furthermore, in order to perform scan A11 using three types of X-ray energy, it is necessary to change the X-ray energy with high frequency, and the energy of the X-ray emitted from the X-ray tube 111 may become unstable. There is also sex. Therefore, the X-ray CT system 10 improves the feasibility of substance discrimination based on three or more kinds of reference substances by the processing of the processing circuit 144 described in detail below.

Specifically, first, the scan function 144a executes the scan A21 by the X-ray of the energy E21 as shown in FIG. That is, the scan function 144a executes the scan A21 without changing the X-ray energy for each view, and collects the projection data set corresponding to the energy E21. Note that FIG. 3 is a diagram for explaining the scan and substance discrimination according to the first embodiment. Further, the scan A21 is an example of the first scan. The energy E21 is an example of the first X-ray energy. The projection data set corresponding to the energy E21 is an example of the first projection data set.

The processing function 144b may perform a process for improving the quality of the projection data set collected by the scan A21. For example, the processing function 144b executes denoising processing on the projection data set collected by the scan A21 by a machine learning method.

For example, the processing function 144b pre-generates a trained model M1 functionalized to remove noise from the projection data set and stores it in memory 141. For example, the processing function 144b uses a combination of low quality projection data sets and high quality projection data sets collected for the same subject or phantom as training data to generate the trained model M1. That is, the processing function 144b generates the trained model M1 by executing machine learning using a low-quality projection data set as input side data and a high-quality projection data set as output side data. Note that, for example, a low quality projection dataset is a projection dataset collected using low dose X-rays, and a high quality projection dataset is a projection dataset collected using high dose X-rays. is there.

Here, the trained model M1 can be configured by, for example, a neural network (Neural Network). A neural network is a network that has a structure in which adjacent layers arranged in layers are connected and information propagates from the input layer side to the output layer side. For example, the processing function 144b generates a trained model M1 by executing deep learning (deep learning) on a multi-layer neural network using the above-mentioned training data. The multi-layer neural network is composed of, for example, an input layer, a plurality of intermediate layers (hidden layers), and an output layer.

As an example, the processing function 144b inputs a low quality projection data set as input side data into the neural network. Here, in the neural network, information is propagated from the input layer side toward the output layer side while being coupled only between adjacent layers in one direction, and the projection data set after denoising is estimated from the output layer. Is output.

The processing function 144b adjusts the parameters of the neural network so that the neural network can output a preferable result when the input side data is input. For example, the processing function 144b adjusts the parameters of the neural network by using a function (error function) representing the proximity between the projection data sets. As an example, the processing function 144b calculates an error function between the high-quality projection data set input as output side data and the projection data set estimated by the neural network, and the calculated error function becomes the minimum. Adjust the parameters so that. That is, the processing function 144b generates the trained model M1 by training the neural network so that the error function becomes the minimum. Further, the processing function 144b stores the generated trained model M1 in the memory 141.

Then, when the scan A21 is executed, the processing function 144b reads the learned model M1 from the memory 141, and executes denoising using the read learned model M1. That is, the processing function 144b acquires the denoised projection data set by inputting the projection data set collected by the scan A21 into the trained model M1.

Although the trained model M1 has been described as being composed of a neural network, the processing function 144b may generate the trained model M1 by a machine learning method other than the neural network. Further, although the processing function 144b has been described as generating the trained model M1, the trained model M1 may be generated by another device.

Next, the processing function 144b reconstructs the reconstructed image I21 from the projection data set collected by the scan A21. Note that the processing function 144b may perform processing for improving the quality of the reconstructed image, as in the case of the projection data set. Next, the scan range of scan A22, which will be described later, is set based on the reconstructed image I21.

As an example, the control function 144c performs rendering processing on the reconstructed image I21 to generate a reference image. Here, as an example of the rendering process, there is a process of generating a two-dimensional image of an arbitrary cross section from the reconstructed image I21 by a cross-section reconstruction method (MPR: Multi Planar Reconstruction). Further, as another example of the rendering process, a two-dimensional image reflecting three-dimensional information is obtained from the reconstructed image I21 by the volume rendering process or the maximum value projection method (MIP). The processing to generate can be mentioned. Next, the control function 144c causes the generated reference image to be displayed on the display 142. Then, the control function 144c sets the scan range of the scan A22 by accepting an input operation from the user who has referred to the reference image.

That is, the scan A21 is a positioning image for setting the scan range of the scan A22. Therefore, it is preferable that the scan A21 is performed over a relatively wide area so as to include the organ to be diagnosed.

Next, the scan function 144a executes the scan A22 with respect to the scan range set in the reference image. For example, the scan function 144a executes the scan A22 by changing the X-ray energy between the energies E22 and the energy E23 for each view. By the scan A22, the scan function 144a collects the projection data set corresponding to the energy E22 and the projection data set corresponding to the energy E23 substantially simultaneously.

The scan A22 is an example of the second scan. The energy E22 is an example of the second X-ray energy. The energy E23 is an example of the third X-ray energy. The energy E21, the energy E22, and the energy E23 are different energies from each other. For example, energy E21 is greater than both energy E22 and energy E23. Also, for example, the energy E21 is smaller than both the energy E22 and the energy E23. Also, for example, the energy E21 is the energy between the energy E22 and the energy E23. The projection data set corresponding to the energy E22 is an example of the second projection data set. The projection data set corresponding to the energy E23 is an example of the third projection data set.

Further, the scan function 144a may be executed in synchronization with the scan A21 and the scan A22 according to the heartbeat or the respiratory cycle of the subject P. That is, the scan function 144a may be executed in synchronization with the scan A21 and the scan A22 so that the position shift between the scan A21 and the scan A22 does not occur due to the periodic movement due to the heartbeat or the respiration.

For example, the scan function 144a acquires the electrocardiographic waveform of the subject P in parallel with the scan A21 and the scan A22. For example, the scan function 144a acquires the electrocardiographic waveform of the subject P with an electrocardiograph attached to the subject P. Then, the scan function 144a executes the scan A22 so that the phase of the electrocardiographic waveform in the scan A22 matches the electrocardiographic waveform in the scan A21.

Further, for example, the scan function 144a acquires the respiratory waveform of the subject P in parallel with the scan A21 and the scan A22. For example, the scan function 144a acquires the respiratory waveform of the subject P by the respiratory sensor. As an example, the scan function 144a acquires a respiration waveform using a laser generator and a receiver as a respiration sensor. Specifically, the scan function 144a processes the signal of the reflected light from the abdominal surface of the subject P, and uses the laser generator and the laser generator based on the time from the laser irradiation to the reception of the reflected light or the phase change of the reflected light signal. The respiratory waveform is acquired by repeatedly calculating the distance from the abdominal surface of the subject in real time. The example of the respiration sensor is not limited to this, and the scan function 144a uses, for example, a pressure sensor attached to the abdomen of the subject P, an optical camera for photographing the subject P, or the like to capture the respiration waveform. It does not matter if it is acquired. Then, the scan function 144a executes the scan A22 so that the phase of the respiratory waveform in the scan A22 matches the respiratory waveform in the scan A21.

Further, the processing function 144b may align the data collected by the scan A21 with the data collected by the scan A22. That is, the processing function 144b aligns the projection data set corresponding to the energy E21 with the projection data set corresponding to the energy E22 and the projection data set corresponding to the energy E23. As a result, the processing function 144b can reduce the influence of the body movement of the subject P or the like that occurs between the scan A21 and the scan A22.

Next, the scanning function 144a separates the projection data set corresponding to the energy E22 and the projection data set corresponding to the energy E23, as shown in FIG. Next, the processing function 144b interpolates the missing portion data for each of the separated projection data sets, and performs reconstruction processing on the interpolated projection data set. For example, the processing function 144b reconstructs the reconstructed image I22 from the projection data set corresponding to the energy E22. The processing function 144b also reconstructs the reconstructed image I23 from the projection data set corresponding to the energy E23.

The processing function 144b may perform processing for improving the quality of the projection data set collected by the scan A22. For example, the processing function 144b executes denoising processing on the projection data set collected by the scan A22 by a machine learning method.

As an example, when the scan A22 is executed, the processing function 144b reads the trained model M1 from the memory 141 and inputs the projection data set corresponding to the energy E22 to the trained model M1. Here, the processing function 144b may input the projection data set before interpolating the data of the missing portion, or may input the projection data set after interpolating the data of the missing portion. As a result, the processing function 144b executes denoising on the projection data set corresponding to the energy E22. Similarly, the processing function 144b performs denoising on the projection data set corresponding to the energy E23. Then, the processing function 144b reconstructs the reconstructed image I22 from the projected data set after denoising corresponding to the energy E22. Further, the processing function 144b reconstructs the reconstructed image I23 from the projected data set after denoising corresponding to the energy E23.

Next, the processing function 144b discriminates the reconstructed image I21, the reconstructed image I22, and the reconstructed image I23 with three types of reference substances. For example, the processing function 144b substitutes the energy E21 for "E1" in the above equation (1), substitutes the energy E22 for "E2", and substitutes the energy E23 for "E3" to solve the simultaneous equations. 3. Material discrimination is performed using three types of reference substances "α, β, γ".

Then, the processing function 144b generates an image showing the result of substance discrimination. For example, the processing function 144b generates a substance discrimination image for each reference substance. As an example, as shown in FIG. 3, the processing function 144b has a substance discrimination image in which the reference substance α is emphasized, a substance discrimination image in which the reference substance β is emphasized, and a substance discrimination image in which the reference substance γ is emphasized. Generate each. Further, the control function 144c causes the generated substance discrimination image to be displayed on the display 142.

That is, the X-ray CT system 10 can discriminate substances with three types of reference substances by executing scan A21 using a single X-ray energy and scan A22 of the kV switching method. Here, the scan A22 changes the X-ray energy between the two types of energy, and the amount of projected data (number of views) for each energy is larger than that shown in FIG. 2B. There is. Further, the scan A22 changes the X-ray energy between the two types of energy, and it is possible to reduce the frequency of changing the X-ray energy as compared with the case shown in FIG. 2B. is there. That is, in the scan A22, the energy of the X-rays emitted from the X-ray tube 111 can be stabilized as compared with the case shown in FIG. 2B.

Therefore, the X-ray CT system 10 can improve the accuracy of substance discrimination by executing the scan A21 and the scan A22. Further, the scan A21, which is a positioning image, is generally performed in a processing flow for image acquisition, and the processing flow is not complicated. From the above, the X-ray CT system 10 can improve the feasibility of substance discrimination using three types of reference substances.

Further, the X-ray CT system 10 uses the result of the scan A21 for the positioning of the scan A22 and also for the processing of substance discrimination. That is, the X-ray CT system 10 can make the exposure of the subject P by the scan A21 more meaningful.

Next, an example of the processing procedure by the X-ray CT system 10 will be described with reference to FIG. FIG. 4 is a flowchart for explaining a series of processes of the X-ray CT system 10 according to the first embodiment.

Step S101 and step S106 correspond to the scanning function 144a. Step S102, step S103, step S107, step S108 and step S109 correspond to the processing function 144b. Step S104, step S105 and step S110 correspond to the control function 144c.

First, the processing circuit 144 executes the scan A21 on the subject P and collects the projection data set corresponding to the energy E21 (step S101). Next, the processing circuit 144 executes the reconstruction process on the projection data set corresponding to the energy E21 to generate the reconstruction image I21 (step S102). Next, the processing circuit 144 generates a reference image by performing rendering processing on the reconstructed image I21 (step S103), and displays the generated reference image on the display 142 (step S104).

Here, the processing circuit 144 determines whether or not the scan range has been set by the user who referred to the reference image (step S105), and if the scan range has not been set, the processing circuit 144 enters a standby state (step S105 negative). .. On the other hand, when the scan range is set (step S105 affirmative), the processing circuit 144 executes the scan A22 for the scan range set in the reference image, and causes the projection data set and the energy E23 corresponding to the energy E22. The corresponding projection datasets are collected at substantially the same time (step S106). Next, the processing circuit 144 executes reconstruction processing on the projection data set corresponding to the energy E22 and the projection data set corresponding to the energy E23, and generates the reconstruction image I22 and the reconstruction image I23 (step S107). ).

Next, the processing circuit 144 discriminates substances with three types of reference substances based on the reconstructed image I21 generated in step S102 and the reconstructed image I22 and the reconstructed image I23 generated in step S107. (Step S108). For example, the processing circuit 144 solves the above equation (1) to discriminate substances using three types of reference substances "α, β, γ". Further, the processing circuit 144 generates a substance discrimination image as an image showing the result of the substance discrimination (step S109). Then, the processing circuit 144 displays the generated substance discrimination image on the display 142 (step S110), and ends the processing.

Although it has been described in FIG. 3 that the X-ray energy is changed for each view, the scan function 144a may change the X-ray energy for each of a plurality of views.

Further, as an image showing the result of substance discrimination, the substance discrimination image generated for each reference substance has been described, but the embodiment is not limited to this. For example, the processing function 144b performs a weighting calculation process based on the mixing ratio of each reference substance using a plurality of substance discrimination images, thereby performing a virtual monochromatic X-ray image, a density image, an effective atomic number image, etc. at a predetermined energy. , Various images can be generated.

Further, it has been described so far that the scan A21 is executed before the scan A22. However, the embodiment is not limited to this. That is, the scan function 144a may execute the scan A22 before the scan A21.

For example, the scan function 144a first executes a scan A22 that collects the projection data set corresponding to the energy E22 and the projection data set corresponding to the energy E23 substantially simultaneously. In this case, the scan A22 is a positioning image for setting the scan range of the scan A21 to be executed later. Therefore, it is preferable that the scan A22 is performed over a relatively wide area so as to include the organ to be diagnosed.

Next, the processing function 144b executes reconstruction processing on the projection data set corresponding to the energy E22 and the projection data set corresponding to the energy E23, and generates the reconstruction image I22 and the reconstruction image I23. Further, the processing function 144b generates a reference image based on at least one of the reconstructed image I22 and the reconstructed image I23. Further, the control function 144c causes the generated reference image to be displayed on the display 142. Further, the control function 144c accepts the setting of the scan range for the reference image from the user. Then, the processing function 144b executes the scan A21 for collecting the projection data set corresponding to the energy E21 with respect to the scan range set in the reference image.

Further, although it has been described that the data collected by the scan A21 and the data collected by the scan A22 are aligned before the reconstruction process is performed, the processing function 144b has performed the reconstruction process. Alignment may be performed at a later stage. That is, the processing function 144b may be used when the reconstructed image I21 is aligned with the reconstructed image I22 and the reconstructed image I23.

As mentioned above, according to the first embodiment, the scan function 144a performs a first scan that collects a first projection data set corresponding to the first X-ray energy. Further, the scanning function 144a has a second projection data set corresponding to a second X-ray energy different from the first X-ray energy, and a third X-ray energy different from the first X-ray energy and the second X-ray energy. A second scan is performed that collects the third projection data set corresponding to the X-ray energy of. In addition, the processing function 144b discriminates substances with three types of reference substances based on the first projection data set, the second projection data set, and the third projection data set. Therefore, the X-ray CT system 10 according to the first embodiment can improve the feasibility of substance discrimination by three kinds of reference substances.

The scan function 144a also performs a second scan by changing the X-ray energy between the second X-ray energy and the third X-ray energy for each one or more views. That is, the scan function 144a performs dual energy collection of the kV switching method as the second scan. Therefore, no special hardware configuration is required in the X-ray CT system 10, and the scan for substance discrimination can be performed with high feasibility.

The scanning function 144a also makes the first X-ray energy larger than both the second X-ray energy and the third X-ray energy, or both the second X-ray energy and the third X-ray energy. Make it smaller and perform a second scan. As a result, the scan function 144a can reduce the energy difference between the second X-ray energy and the third X-ray energy and stabilize the output when switching the X-ray energy in the second scan. it can.

(Second Embodiment)
In the first embodiment described above, a case where dual energy collection of the kV switching method is performed as the second scan has been described. On the other hand, in the second embodiment, a case where dual energy collection of the stacked detector method (also referred to as a dual layer method) is performed as the second scan will be described.

The X-ray CT system 10 according to the second embodiment has the same configuration as the X-ray CT system 10 according to the first embodiment shown in FIG. However, the X-ray CT system 10 according to the second embodiment includes a stacked detector as the X-ray detector 112. For example, the X-ray detector 112 is composed of a first layer 112a and a second layer 112b, and spectroscopically detects X-rays emitted from an X-ray tube 111. Hereinafter, the points described in the first embodiment are designated by the same reference numerals as those in FIG. 1, and the description thereof will be omitted.

For example, the scan function 144a first executes an X-ray scan A31 of energy E31. Specifically, the scan function 144a executes the scan A31 by rotating the rotating portion while generating X-rays of energy E31 from the X-ray tube 111 by controlling the X-ray high voltage device 114.

Here, as shown in the scan A31 of FIG. 5, the X-ray detector 112 detects the X-rays of the energy E32 in the first layer 112a and the X-rays of the energy E33 in the second layer 112b. That is, the X-ray detector 112 detects the X-rays of the energy E31 emitted from the X-ray tube 111 by separating them into the X-rays of the energy E32 and the X-rays of the energy E33. Note that FIG. 5 is a diagram for explaining the dual layer type scan according to the second embodiment.

In addition, the scanning function 144a synthesizes the X-ray-based projection data set detected in the first layer 112a and the X-ray-based projection data set detected in the second layer 112b. That is, the scan function 144a generates a projection data set corresponding to the energy E31 by synthesizing the projection data set corresponding to the energy E32 and the projection data set corresponding to the energy E33. The scan A31 is an example of the first scan. The energy E31 is an example of the first X-ray energy. The projection data set corresponding to the energy E31 is an example of the first projection data set.

Next, the processing function 144b reconstructs the reconstructed image I31 from the projection data set corresponding to the energy E31. Next, the control function 144c performs rendering processing on the reconstructed image I31 to generate a reference image, and displays the generated reference image on the display 142. Then, the control function 144c sets the scan range of the scan A32, which will be described later, by accepting an input operation from the user who has referred to the reference image.

Although it has been described that the reference image is generated based on the reconstructed image I31, the embodiment is not limited to this. For example, the processing function 144b may generate the reconstructed image I32 based on the projection data set corresponding to the energy E32, and the control function 144c may generate the reference image based on the reconstructed image I32. Further, for example, the processing function 144b may generate the reconstructed image I33 based on the projection data set corresponding to the energy E33, and the control function 144c may generate the reference image based on the reconstructed image I33. That is, the control function 144c generates a reference image based on the detection result of at least one of the first layer 112a and the second layer 112b.

Next, the scan function 144a executes the scan A32 with respect to the scan range set in the reference image. Specifically, the scan function 144a executes the scan A32 by rotating the rotating portion while generating X-rays of energy E34 from the X-ray tube 111 by controlling the X-ray high voltage device 114.

Here, as shown in the scan A32 of FIG. 5, the X-ray detector 112 detects the X-ray of the energy E35 in the first layer 112a and the X-ray of the energy E36 in the second layer 112b. That is, the X-ray detector 112 separates and detects the X-rays of the energy E34 emitted from the X-ray tube 111 into the X-rays of the energy E35 and the X-rays of the energy E36.

The scan A32 is an example of the second scan. The energy E35 is an example of the second X-ray energy. The energy E36 is an example of the third X-ray energy. In the case shown in FIG. 5, the energy E31 which is the first X-ray energy is smaller than both the energy E35 and the energy E36 which are the second and third X-ray energies. The projection data set corresponding to the energy E35 is an example of the second projection data set. The projection data set corresponding to the energy E36 is an example of the third projection data set. That is, the scanning function 144a collects the projection data set corresponding to the energy E35, which is the second X-ray energy, and the projection data set corresponding to the energy E36, which is the third X-ray energy, substantially simultaneously.

Next, the processing function 144b reconstructs the reconstructed image I35 from the projection data set corresponding to the energy E35. The processing function 144b also reconstructs the reconstructed image I36 from the projection data set corresponding to the energy E36.

The scan function 144a may be executed in synchronization with the scan A31 and the scan A32 according to the heartbeat or the respiratory cycle of the subject P. Further, the processing function 144b may align the data collected by the scan A31 with the data collected by the scan A32. Here, the processing function 144b may perform the alignment at the stage of the projection data set, or may perform the alignment at the stage of the reconstructed image.

Next, the processing function 144b discriminates the reconstructed image I31, the reconstructed image I35, and the reconstructed image I36 with three types of reference substances. For example, the processing function 144b substitutes the energy E31 for "E1" in the above equation (1), substitutes the energy E35 for "E2", and substitutes the energy E36 for "E3" to solve the simultaneous equations. 3. Material discrimination is performed using three types of reference substances "α, β, γ".

Then, the processing function 144b generates an image showing the result of substance discrimination. For example, the processing function 144b generates a substance discrimination image for each reference substance. For example, the processing function 144b generates a substance discrimination image in which the reference substance α is emphasized, a substance discrimination image in which the reference substance β is emphasized, and a substance discrimination image in which the reference substance γ is emphasized, respectively. Further, the processing function 144b performs a weighting calculation process based on the mixing ratio of each reference substance using a plurality of substance discrimination images, thereby performing a virtual monochromatic X-ray image, a density image, an effective atomic number image, etc. at a predetermined energy. , Various images can also be generated. Further, the control function 144c causes the display 142 to display an image showing the result of substance discrimination.

As mentioned above, according to the second embodiment, the scan function 144a performs a first scan that collects a first projection data set corresponding to the first X-ray energy. Further, the scan function 144a executes a second scan using the stacked X-ray detector 112, and has a second projection data set corresponding to the second X-ray energy and a third X-ray energy corresponding to the third X-ray energy. Collect 3 projected datasets at virtually the same time. In addition, the processing function 144b discriminates substances with three types of reference substances based on the first projection data set, the second projection data set, and the third projection data set. Therefore, the X-ray CT system 10 according to the second embodiment can improve the feasibility of substance discrimination based on the three types of reference substances.

As another method for discriminating substances based on three types of reference substances, for example, it is conceivable to use a laminated detector having three or more layers. However, using such special hardware is not feasible in terms of cost and the like. On the other hand, the X-ray CT system 10 can realize substance discrimination by three kinds of reference substances by a two-layer laminated detector which is generally used.

Further, although the energy E31 shown in FIG. 5 has been described as an example of the first X-ray energy, the embodiment is not limited to this. For example, the processing function 144b can also discriminate substances with three types of reference substances using the energy E32 shown in FIG. 5 as the first X-ray energy. As an example, the processing function 144b generates the reconstructed image I32 based on the projection data set corresponding to the energy E32. Then, the processing function 144b discriminates the reconstructed image I32, the reconstructed image I35, and the reconstructed image I36 by three kinds of reference substances. For example, the processing function 144b substitutes the energy E32 for "E1" in the above equation (1), substitutes the energy E35 for "E2", and substitutes the energy E36 for "E3" to solve the simultaneous equations. 3. Material discrimination is performed using three types of reference substances "α, β, γ". Similarly, the processing function 144b can also discriminate substances with three types of reference substances using the energy E33 shown in FIG. 5 as the first X-ray energy.

Further, the energy E35 and the energy E36 shown in FIG. 5 have been described as examples of the second and third X-ray energies, but the embodiment is not limited thereto. For example, the processing function 144b can also discriminate substances with three types of reference substances using energy E35 and energy E34 as second and third X-ray energies. Further, for example, the processing function 144b can also discriminate substances with three types of reference substances using energy E34 and energy E36 as second and third X-ray energies.

Further, although the case of performing substance discrimination using three types of reference substances has been described, the processing function 144b can also perform substance discrimination using four or more types of reference substances. For example, the processing function 144b is based on a projection data set corresponding to energy E32, a projection data set corresponding to energy E33, a projection data set corresponding to energy E35, and a projection data set corresponding to energy E36. Material discrimination by substance can be performed. In this case, the energy E32 is an example of the first X-ray energy, the energy E35 is an example of the second X-ray energy, the energy E36 is an example of the third X-ray energy, and the energy E33 is an example. This is an example of the fourth X-ray energy. Further, the projection data set corresponding to the energy E32 is an example of the first projection data set, the projection data set corresponding to the energy E35 is an example of the second projection data set, and the projection data set corresponding to the energy E36 is the first. The 3 projection data set is an example, and the projection data set corresponding to the energy E33 is an example of the 4th projection data set.

Similarly, the processing function 144b can perform substance discrimination with five kinds of reference substances based on five projection data sets corresponding to five energies out of the six energies shown in FIG. Similarly, the processing function 144b can perform substance discrimination by six kinds of reference substances based on six projection data sets corresponding to the six energies shown in FIG.

In FIG. 5, the energy E31, which is the energy of the X-rays emitted from the X-ray tube 111 in the scan A31, is smaller than the energy E34, which is the energy of the X-rays emitted from the X-ray tube 111 in the scan A32. Explained as. However, the embodiment is not limited to this. For example, the energy E31 may be larger than the energy E34.

Further, the energy E31 and the energy E34 may have the same magnitude. In this case, the energy E32 and the energy E35 have substantially the same size, and the energy E33 and the energy E36 have substantially the same size. Therefore, the processing function 144b includes at least one of the projection data set corresponding to the energy E31 and the projection data set corresponding to the energy E34, and at least one of the projection data set corresponding to the energy E32 and the projection data set corresponding to the energy E35. , Material discrimination with three types of reference materials can be performed based on at least one of the projection data set corresponding to the energy E33 and the projection data set corresponding to the energy E36.

Moreover, although the case where the scan A31 and the scan A32 are executed has been described, one of these two scans may be omitted. For example, the scan function 144a may be a case where only the scan A31 is executed. In this case, the processing function 144b discriminates substances by three types of reference substances based on the projection data set corresponding to the energy E31, the projection data set corresponding to the energy E32, and the projection data set corresponding to the energy E33. Can be done.

Further, the X-ray CT system 10 may be a case where the second scan is executed by using a photon counting type detector instead of the stacked detector. That is, the X-ray CT system 10 may perform photon counting type dual energy collection as the second scan.

For example, the scan function 144a first executes an X-ray scan A41 of energy E41. Specifically, the scan function 144a executes the scan A41 by rotating the rotating portion while generating X-rays of energy E41 from the X-ray tube 111 by controlling the X-ray high voltage device 114. Further, the X-ray detector 1121 detects X-rays that have passed through the subject P.

Here, the scan function 144a counts the number of X-ray photons incident on each detection element by counting the number of electric signals (pulses) output from the X-ray detector 1121 and with respect to this signal. By performing a predetermined arithmetic process, the energy value of the X-ray photon that caused the output of the signal is measured. As a result, the X-ray CT system 10 can count the number of X-ray photons for each set energy bin.

For example, the scan function 144a counts the number of X-ray photons in scan A41 using only one energy bin. As a result, the scanning function 144a collects the projection data set corresponding to the energy E41. The scan A41 is an example of the first scan. The energy E41 is an example of the first X-ray energy. The projection data set corresponding to the energy E41 is an example of the first projection data set.

Next, the processing function 144b reconstructs the reconstructed image I41 from the projection data set corresponding to the energy E41. Next, the control function 144c performs rendering processing on the reconstructed image I41 to generate a reference image, and displays the generated reference image on the display 142. Then, the control function 144c sets the scan range of the scan A42, which will be described later, by accepting an input operation from the user who has referred to the reference image.

Next, the scan function 144a executes the scan A42 for the scan range set in the reference image, and the X-ray detector 1121 detects the X-rays that have passed through the subject P. The energy of the X-rays irradiated to the subject P in the scan A42 may be the energy E41 as in the scan A41, or may be different from the energy E41. Here, the scan function 144a sets, for example, two energy bins corresponding to each of the energy E42 and the energy E43, and sets the number of X-ray photons of the energy E42 and the number of X-ray photons of the energy E43. Count each. As a result, the scan function 144a collects the projection data set corresponding to the energy E42 and the projection data set corresponding to the energy E43.

The scan A42 is an example of the second scan. The energy E42 is an example of the second X-ray energy. The energy E43 is an example of the third X-ray energy. Here, the energy E41, the energy E42, and the energy E43 are different energies from each other. For example, energy E41 is greater than both energy E42 and energy E43. Also, for example, the energy E41 is smaller than both the energy E42 and the energy E43. Also, for example, the energy E41 is the energy between the energy E42 and the energy E43. The projection data set corresponding to the energy E42 is an example of the second projection data set. The projection data set corresponding to the energy E43 is an example of the third projection data set.

Next, the processing function 144b reconstructs the reconstructed image I42 from the projection data set corresponding to the energy E42. The processing function 144b also reconstructs the reconstructed image I43 from the projection data set corresponding to the energy E43. The scan function 144a may be executed in synchronization with the scan A41 and the scan A42 according to the heartbeat or the respiratory cycle of the subject P. Further, the processing function 144b may align the data collected by the scan A41 with the data collected by the scan A42. Here, the processing function 144b may perform the alignment at the stage of the projection data set, or may perform the alignment at the stage of the reconstructed image.

Next, the processing function 144b discriminates the reconstructed image I41, the reconstructed image I42, and the reconstructed image I43 with three types of reference substances. For example, the processing function 144b substitutes the energy E41 for "E1" in the above equation (1), substitutes the energy E42 for "E2", and substitutes the energy E43 for "E3" to solve the simultaneous equations. 3. Material discrimination is performed using three types of reference substances "α, β, γ".

Then, the processing function 144b generates an image showing the result of substance discrimination. For example, the processing function 144b generates a substance discrimination image for each reference substance. For example, the processing function 144b generates a substance discrimination image in which the reference substance α is emphasized, a substance discrimination image in which the reference substance β is emphasized, and a substance discrimination image in which the reference substance γ is emphasized, respectively. Further, the processing function 144b performs a weighting calculation process based on the mixing ratio of each reference substance using a plurality of substance discrimination images, thereby performing a virtual monochromatic X-ray image, a density image, an effective atomic number image, etc. at a predetermined energy. , Various images can also be generated. Further, the control function 144c causes the display 142 to display an image showing the result of substance discrimination.

As mentioned above, according to the second embodiment, the scan function 144a performs a first scan that collects a first projection data set corresponding to the first X-ray energy. The scan function 144a also performs a second scan using a photon counting type X-ray detector 1121 and corresponds to a second projection data set corresponding to the second X-ray energy and a third X-ray energy. Collect the third projection dataset at substantially the same time. In addition, the processing function 144b discriminates substances with three types of reference substances based on the first projection data set, the second projection data set, and the third projection data set. Therefore, the X-ray CT system 10 according to the second embodiment can improve the feasibility of substance discrimination based on the three types of reference substances.

As another method for discriminating substances based on three types of reference substances, for example, it is conceivable to set three or more energy bins and perform photon counting method multi-energy collection. However, as the number of energy bins increases, the amount of data handled at one time and the number of circuits used increase, which causes problems in terms of data transmission, heat generation, and cost. Therefore, it is not feasible to set many energy bins. On the other hand, the X-ray CT system 10 can realize substance discrimination by three kinds of reference substances while suppressing the number of energy bins.

Further, although the case of performing substance discrimination using three types of reference substances has been described, the processing function 144b can also perform substance discrimination using four or more types of reference substances. For example, the processing function 144b sets two energy bins in scan A41 and counts the number of X-ray photons of energy E41 and the number of X-ray photons of energy E44, respectively. Here, the energy E44 is an example of the fourth X-ray energy, and is an energy different from the energy E41, the energy E42, and the energy E43. The projection data set corresponding to the energy E44 is an example of the fourth projection data set.

That is, the scan function 144a collects the projection data set corresponding to the energy E41 and the projection data set corresponding to the energy E44 substantially at the same time by executing the scan A41. In this case, the processing function 144b can also perform substance discrimination using four types of reference substances. That is, the processing function 144b has four types of references based on the projection data set corresponding to the energy E41, the projection data set corresponding to the energy E42, the projection data set corresponding to the energy E43, and the projection data set corresponding to the energy E44. Material discrimination by substance can be performed.

(Third Embodiment)
In the first and second embodiments described above, a case where dual energy collection of the kV switching method, the dual layer method, or the photon counting method is performed as the second scan has been described. On the other hand, in the third embodiment, a case where dual energy collection of a dual source method using two X-ray tubes is performed as a second scan will be described.

The X-ray CT system 10 according to the third embodiment includes an X-ray tube 1111 and an X-ray tube 1112 as the X-ray tube 111. Further, the X-ray CT system 10 according to the third embodiment is irradiated from the X-ray detector 1122, which detects the X-rays emitted from the X-ray tube 1111, and the X-ray tube 1112, as the X-ray detector 112. It is provided with an X-ray detector 1123 for detecting X-rays. Hereinafter, the points described in the first to second embodiments are designated by the same reference numerals as those in FIG. 1, and the description thereof will be omitted.

For example, the scan function 144a first executes an X-ray scan A51 of energy E51. For example, the scan function 144a executes the scan A51 by rotating the rotating portion while generating X-rays of energy E51 from the X-ray tube 1111 by controlling the X-ray high voltage device 114. As a result, the scanning function 144a collects the projection data set corresponding to the energy E51. The scan A51 is an example of the first scan. The energy E51 is an example of the first X-ray energy. The projection data set corresponding to the energy E51 is an example of the first projection data set.

Next, the processing function 144b reconstructs the reconstructed image I51 from the projection data set corresponding to the energy E51. Next, the control function 144c performs rendering processing on the reconstructed image I51 to generate a reference image, and displays the generated reference image on the display 142. Then, the control function 144c sets the scan range of the scan A52, which will be described later, by accepting an input operation from the user who has referred to the reference image.

Next, the scan function 144a executes the scan A52 with respect to the scan range set in the reference image. Specifically, the scanning function 144a generates X-rays of energy E52 from the X-ray tube 1111 and X-rays of energy E53 from the X-ray tube 1112 by controlling the X-ray high-voltage device 114. Further, the scan function 144a executes the scan A52 by rotating the rotating portion including the X-ray tube 1111 and the X-ray tube 1112.

The scan A52 is an example of the second scan. The energy E52 is an example of the second X-ray energy. The energy E53 is an example of the third X-ray energy. Here, the energy E51, the energy E52, and the energy E53 are different energies from each other. For example, energy E51 is greater than both energy E52 and energy E53. Also, for example, the energy E51 is smaller than both the energy E52 and the energy E53. Also, for example, the energy E51 is the energy between the energy E52 and the energy E53. The projection data set corresponding to the energy E52 is an example of the second projection data set. The projection data set corresponding to the energy E53 is an example of the third projection data set. That is, the scanning function 144a collects the projection data set corresponding to the energy E52, which is the second X-ray energy, and the projection data set corresponding to the energy E53, which is the third X-ray energy, substantially simultaneously.

Next, the processing function 144b reconstructs the reconstructed image I52 from the projection data set corresponding to the energy E52. The processing function 144b also reconstructs the reconstructed image I53 from the projection data set corresponding to the energy E53.

The scan function 144a may be executed in synchronization with the scan A51 and the scan A52 according to the heartbeat or the respiratory cycle of the subject P. Further, the processing function 144b may align the data collected by the scan A51 with the data collected by the scan A52. Here, the processing function 144b may perform the alignment at the stage of the projection data set, or may perform the alignment at the stage of the reconstructed image.

Next, the processing function 144b discriminates the reconstructed image I51, the reconstructed image I52, and the reconstructed image I53 with three types of reference substances. For example, the processing function 144b substitutes the energy E51 for "E1" in the above equation (1), substitutes the energy E52 for "E2", and substitutes the energy E53 for "E3" to solve the simultaneous equations. 3. Material discrimination is performed using three types of reference substances "α, β, γ".

Then, the processing function 144b generates an image showing the result of substance discrimination. For example, the processing function 144b generates a substance discrimination image for each reference substance. For example, the processing function 144b generates a substance discrimination image in which the reference substance α is emphasized, a substance discrimination image in which the reference substance β is emphasized, and a substance discrimination image in which the reference substance γ is emphasized, respectively. Further, the processing function 144b performs a weighting calculation process based on the mixing ratio of each reference substance using a plurality of substance discrimination images, thereby performing a virtual monochromatic X-ray image, a density image, an effective atomic number image, etc. at a predetermined energy. , Various images can also be generated. Further, the control function 144c causes the display 142 to display an image showing the result of substance discrimination.

As mentioned above, according to the third embodiment, the scan function 144a performs a first scan that collects a first projection data set corresponding to the first X-ray energy. Further, the scan function 144a executes the second scan by irradiating the X-ray tube 1111 with the X-ray of the second X-ray energy and irradiating the X-ray tube 1112 with the X-ray of the third X-ray energy. Then, the second projection data set corresponding to the second X-ray energy and the third projection data set corresponding to the third X-ray energy are collected substantially at the same time. In addition, the processing function 144b discriminates substances with three types of reference substances based on the first projection data set, the second projection data set, and the third projection data set. Therefore, the X-ray CT system 10 according to the third embodiment can improve the feasibility of substance discrimination based on the three types of reference substances.

As another method for discriminating substances from three types of reference substances, for example, it is conceivable to use three or more sets of X-ray tubes and X-ray detectors. However, using such special hardware is not feasible in terms of cost and the like. On the other hand, the X-ray CT system 10 is a commonly used dual source system, and can realize substance discrimination by three kinds of reference substances.

Further, although the case where the scan A51 is executed by using the X-ray tube 1111 has been described, the scan function 144a may execute the scan A52 by using the X-ray tube 1112.

Further, the scan function 144a may execute the scan A51 by using both the X-ray tube 1111 and the X-ray tube 1112. For example, the scanning function 144a irradiates the X-ray tube 1111 with the X-ray of the energy E51 and irradiates the X-ray tube 1112 with the X-ray of the energy E54. Further, the scan function 144a executes the scan A51 by rotating the rotating portion including the X-ray tube 1111 and the X-ray tube 1112. Here, the energy E54 is an example of the fourth X-ray energy, and is an energy different from the energy E51, the energy E52, and the energy E53. The projection data set corresponding to the energy E54 is an example of the fourth projection data set.

That is, the scan function 144a collects the projection data set corresponding to the energy E51 and the projection data set corresponding to the energy E54 substantially at the same time by executing the scan A51. In this case, the processing function 144b can also perform substance discrimination using four types of reference substances. That is, the processing function 144b has four types of references based on the projection data set corresponding to the energy E51, the projection data set corresponding to the energy E52, the projection data set corresponding to the energy E53, and the projection data set corresponding to the energy E54. Material discrimination by substance can be performed.

(Fourth Embodiment)
In the first to third embodiments described above, a case where dual energy collection of the kV switching method, the dual layer method, the photon counting method, or the dual source method is performed as the second scan has been described. On the other hand, in the fourth embodiment, a case where dual energy collection of the split method is performed as the second scan will be described.

The X-ray CT system 10 according to the fourth embodiment includes, as a wedge 116, for example, a filter that divides X-rays emitted from an X-ray tube 111 into a plurality of X-rays having different energies. For example, the X-ray CT system 10 includes an X-ray filter 116a and an X-ray filter 116b as wedges 116. The X-ray filter 116a and the X-ray filter 116b are different in material, thickness, and the like, and divide X-rays having the same energy into a plurality of X-rays having different energies. The X-ray filter 116a is an example of the first X-ray filter. The X-ray filter 116b is an example of a second X-ray filter. Hereinafter, the points described in the first to third embodiments are designated by the same reference numerals as those in FIG. 1, and the description thereof will be omitted.

For example, the scan function 144a first executes an X-ray scan A61 of energy E61. For example, the scan function 144a attenuates the X-rays emitted from the X-ray tube 111 to the energy E61 by the X-ray filter 116a, the X-ray filter 116b, or another X-ray filter, and executes the scan A61. As a result, the scanning function 144a collects the projection data set corresponding to the energy E61. The scan A61 is an example of the first scan. The energy E61 is an example of the first X-ray energy. The projection data set corresponding to the energy E61 is an example of the first projection data set.

Next, the processing function 144b reconstructs the reconstructed image I61 from the projection data set corresponding to the energy E61. Next, the control function 144c performs rendering processing on the reconstructed image I61 to generate a reference image, and displays the generated reference image on the display 142. Then, the control function 144c sets the scan range of the scan A62, which will be described later, by accepting an input operation from the user who has referred to the reference image.

Next, the scan function 144a executes the scan A62 for the scan range set in the reference image. Specifically, the scan function 144a attenuates the X-rays emitted from the X-ray tube 111 to the energy E62 by the X-ray filter 116a, attenuates the X-rays to the energy E63 by the X-ray filter 116b, and executes the scan A62. .. More specifically, the scanning function 144a refers to the X-ray filter 116a and the X-ray filter 116b in a state where the X-ray filter 116a and the X-ray filter 116b are arranged in the Z-axis direction (column direction) shown in FIG. X-rays are irradiated from the X-ray tube 111. As a result, the scan function 144a can execute the scan A62 in a state where the X-rays of the energy E62 and the X-rays of the energy E63 are distributed in the column direction.

The scan A62 is an example of the second scan. The energy E62 is an example of the second X-ray energy. The energy E63 is an example of the third X-ray energy. Here, the energy E61, the energy E62, and the energy E63 are different energies from each other. For example, energy E61 is greater than both energy E62 and energy E63. Also, for example, the energy E61 is smaller than both the energy E62 and the energy E63. Also, for example, the energy E61 is the energy between the energy E62 and the energy E63. The projection data set corresponding to the energy E62 is an example of the second projection data set. The projection data set corresponding to the energy E63 is an example of the third projection data set. That is, the scanning function 144a collects the projection data set corresponding to the energy E62, which is the second X-ray energy, and the projection data set corresponding to the energy E63, which is the third X-ray energy, substantially simultaneously.

Next, the processing function 144b reconstructs the reconstructed image I62 from the projection data set corresponding to the energy E62. The processing function 144b also reconstructs the reconstructed image I63 from the projection data set corresponding to the energy E63.

The scan function 144a may be executed in synchronization with the scan A61 and the scan A62 according to the heartbeat or the respiratory cycle of the subject P. Further, the processing function 144b may align the data collected by the scan A61 with the data collected by the scan A62. Here, the processing function 144b may perform the alignment at the stage of the projection data set, or may perform the alignment at the stage of the reconstructed image.

Next, the processing function 144b discriminates the reconstructed image I61, the reconstructed image I62, and the reconstructed image I63 with three types of reference substances. For example, the processing function 144b substitutes the energy E61 for "E1" in the above equation (1), substitutes the energy E62 for "E2", and substitutes the energy E63 for "E3" to solve the simultaneous equations. 3. Material discrimination is performed using three types of reference substances "α, β, γ".

Then, the processing function 144b generates an image showing the result of substance discrimination. For example, the processing function 144b generates a substance discrimination image for each reference substance. For example, the processing function 144b generates a substance discrimination image in which the reference substance α is emphasized, a substance discrimination image in which the reference substance β is emphasized, and a substance discrimination image in which the reference substance γ is emphasized, respectively. Further, the processing function 144b performs a weighting calculation process based on the mixing ratio of each reference substance using a plurality of substance discrimination images, thereby performing a virtual monochromatic X-ray image, a density image, an effective atomic number image, etc. at a predetermined energy. , Various images can also be generated. Further, the control function 144c causes the display 142 to display an image showing the result of substance discrimination.

As mentioned above, according to the fourth embodiment, the scan function 144a performs a first scan that collects a first projection data set corresponding to the first X-ray energy. Further, the scan function 144a uses an X-ray filter 116a that attenuates the transmitted X-rays to the second X-ray energy and an X-ray filter 116b that attenuates the transmitted X-rays to the third X-ray energy. Two scans are performed to collect the second projection data set corresponding to the second X-ray energy and the third projection data set corresponding to the third X-ray energy substantially simultaneously. In addition, the processing function 144b discriminates substances with three types of reference substances based on the first projection data set, the second projection data set, and the third projection data set. Therefore, the X-ray CT system 10 according to the fourth embodiment can improve the feasibility of substance discrimination based on the three types of reference substances.

For example, as another method for discriminating substances based on three types of reference substances, for example, it is conceivable to use three or more types of X-ray filters. However, using such special hardware is not feasible in terms of cost and the like. On the other hand, the X-ray CT system 10 can realize substance discrimination by three kinds of reference substances by two kinds of commonly used X-ray filters.

Although the case where the scan A62 is executed by using the X-ray filter 116a and the X-ray filter 116b has been described, the scan function 144a executes the scan A62 by using only one of these two X-ray filters. You can do it.

For example, the scan function 144a irradiates the X-ray of the energy E62 from the X-ray tube 111, attenuates a part of the X-ray to the energy E63 by the X-ray filter 116b, and executes the scan A62. More specifically, the scanning function 144a attenuates X-rays in a predetermined range in the column direction from energy E62 to energy E63 by the X-ray filter 116b, and irradiates the subject P with energy. The X-rays that have not been attenuated by the X-ray filter 116b are irradiated to the subject P with the energy E62. As a result, the scan function 144a executes the scan A62 in a state where the X-rays of the energy E62 and the X-rays of the energy E63 are distributed in the column direction, and the projection data set corresponding to the energy E62 and the projection corresponding to the energy E63 are projected. Data sets can be collected at virtually the same time.

Further, the scan function 144a may execute dual energy collection in the scan A61. For example, the scanning function 144a attenuates X-rays in a predetermined range in the column direction from the X-ray tube 111 to energy E61 by the X-ray filter 116a, and energy other X-rays by the X-ray filter 116b. Attenuate to E64 and perform scan A61. Further, for example, the scanning function 144a attenuates the X-rays in a predetermined range in the column direction among the X-rays of the energy E61 emitted from the X-ray tube 111 from the energy E61 to the energy E64 by the X-ray filter 116b, and scans the X-rays. Execute A61. As a result, the scan function 144a executes the scan A61 in a state where the X-rays of the energy E61 and the X-rays of the energy E64 are distributed in the column direction, and the projection data set corresponding to the energy E61 and the projection corresponding to the energy E64 are projected. Collect the dataset at virtually the same time. Here, the energy E64 is an example of the fourth X-ray energy, and is an energy different from the energy E61, the energy E62, and the energy E63. The projection data set corresponding to the energy E64 is an example of the fourth projection data set.

When the projection data set corresponding to the energy E61 and the projection data set corresponding to the energy E64 are collected by the scan A61, the processing function 144b can perform substance discrimination by four kinds of reference substances. That is, the processing function 144b has four types of references based on the projection data set corresponding to the energy E61, the projection data set corresponding to the energy E62, the projection data set corresponding to the energy E63, and the projection data set corresponding to the energy E64. Material discrimination by substance can be performed.

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

For example, although the description has been made so far that the scan target area is set by the user, the embodiment is not limited to this. For example, the control function 144c may automatically set the scan target area by analyzing the reconstructed image or the reference image generated based on the reconstructed image and extracting the organ or the like to be diagnosed.

Further, although the above equation (1) has been described with "μ" as the linear attenuation coefficient and "c" as the mixing amount, the embodiment is not limited to this. For example, the processing function 144b may solve the equation (1) with "μ" in each substance as the mass attenuation coefficient and "c" as the density.

Further, although it has been described that the substance discrimination is performed at the stage after the reconstruction treatment is performed, the treatment function 144b may perform the substance discrimination at the stage before the reconstruction treatment is performed. That is, the processing function 144b may perform substance discrimination by solving the simultaneous equations of the equation (1) for each pixel of the projection data set.

Further, although the substance discrimination has been described as being performed by the X-ray CT system 10, the embodiment is not limited to this. For example, substance discrimination may be performed in another device different from the X-ray CT system 10. Hereinafter, this point will be described by taking the medical information processing system 1 shown in FIG. 6 as an example. FIG. 6 is a block diagram showing an example of the configuration of the medical information processing system 1 according to the fifth embodiment. The medical information processing system 1 includes an X-ray CT system 10 and a medical processing device 20 that executes substance discrimination.

As shown in FIG. 6, the X-ray CT system 10 and the medical processing device 20 are connected to each other via a network NW. Here, the place where the X-ray CT system 10 and the medical processing device 20 are installed is arbitrary as long as it can be connected via the network NW. For example, the medical processing device 20 may be installed in a hospital different from the X-ray CT system 10. That is, the network NW may be configured by a local network closed in the hospital, or may be a network via the Internet. Further, although one X-ray CT system 10 is shown in FIG. 6, the medical information processing system 1 may include a plurality of X-ray CT systems 10.

The medical processing device 20 is realized by a computer device such as a workstation. For example, the medical processing apparatus 20 has a memory 21, a display 22, an input interface 23, and a processing circuit 24, as shown in FIG.

The memory 21 is realized by, for example, a semiconductor memory element such as a RAM or a flash memory, a hard disk, an optical disk, or the like. For example, the memory 21 stores various data transmitted from the X-ray CT system 10. Further, for example, the memory 21 stores a program for the circuit included in the medical processing device 20 to realize its function. The memory 21 may be realized by a server group (cloud) connected to the medical processing device 20 via the network NW.

The display 22 displays various information. For example, the display 22 displays an image showing the result of substance discrimination by the processing circuit 24, or displays a GUI or the like for accepting various operations from the user. For example, the display 22 is a liquid crystal display or a CRT display. The display 22 may be a desktop type, or may be composed of a tablet terminal or the like capable of wireless communication with the main body of the medical processing device 20.

The input interface 23 receives various input operations from the user, converts the received input operations into electric signals, and outputs the received input operations to the processing circuit 24. For example, the input interface 23 receives from the user reconstruction conditions for reconstructing the reconstructed image, image processing conditions for generating a CT image for display from the reconstructed image, and the like. For example, the input interface 23 includes a mouse, a keyboard, a trackball, a switch, a button, a joystick, a touch pad for performing input operations by touching an operation surface, a touch screen in which a display screen and a touch pad are integrated, and an optical sensor. It is realized by the non-contact input circuit, voice input circuit, etc. used. The input interface 23 may be composed of a tablet terminal or the like capable of wireless communication with the main body of the medical processing device 20. Further, the input interface 23 is not limited to one provided with physical operation parts such as a mouse and a keyboard. For example, an example of the input interface 23 is an electric signal processing circuit that receives an electric signal corresponding to an input operation from an external input device provided separately from the medical processing device 20 and outputs the electric signal to the processing circuit 24. include.

The processing circuit 24 controls the operation of the entire medical processing device 20 by executing the processing function 24a and the control function 24b. The processing function 24a is an example of a processing unit. The processing by the processing circuit 24 will be described later.

In the medical processing device 20 shown in FIG. 6, each processing function is stored in the memory 21 in the form of a program that can be executed by a computer. The processing circuit 24 is a processor that realizes a function corresponding to each program by reading a program from the memory 21 and executing the program. In other words, the processing circuit 24 in the state where the program is read has a function corresponding to the read program.

Although it has been described in FIG. 6 that the processing function 24a and the control function 24b are realized by a single processing circuit 24, a plurality of independent processors are combined to form the processing circuit 24, and each processor is programmed. The function may be realized by executing. Further, each processing function of the processing circuit 24 may be realized by being appropriately distributed or integrated into a single or a plurality of processing circuits.

Further, the processing circuit 24 may realize the function by utilizing the processor of the external device connected via the network NW. For example, the processing circuit 24 reads a program corresponding to each function from the memory 21 and executes it, and also uses a server group (cloud) connected to the medical processing device 20 via a network NW as a computational resource. Each function shown in FIG. 6 is realized.

For example, first, the scan function 144a in the X-ray CT system 10 executes a scan A71 for the subject P to collect a projection data set corresponding to the energy E71. The scan function 144a also executes a second scan that collects the projection data set corresponding to the energy E72 and the projection data set corresponding to the energy E73 substantially simultaneously.

Here, the scan A71 is an example of the first scan, and the scan A72 is an example of the second scan. Further, the energy E71 is an example of the first X-ray energy, the energy E72 is an example of the second X-ray energy, and the energy E73 is an example of the third X-ray energy. The energy E71, the energy E72, and the energy E73 are different energies from each other. Further, the projection data set corresponding to the energy E71 is an example of the first projection data set, the projection data set corresponding to the energy E72 is an example of the second projection data set, and the projection data set corresponding to the energy E73 is the first. This is an example of a three-projection data set.

The scan function 144a may execute the scan A71 before the scan A72 or the scan A72 before the scan A71. Further, the scan function 144a may execute the scan A72 by any of the kV switching method, the dual layer method, the photon counting method, the dual source method, and the split method.

Next, the processing function 144b reconstructs the reconstructed image I71 from the projection data set corresponding to the energy E71. The processing function 144b also reconstructs the reconstructed image I72 from the projection data set corresponding to the energy E72. The processing function 144b also reconstructs the reconstructed image I73 from the projection data set corresponding to the energy E73. Further, the control function 144c transmits the reconstructed image I71, the reconstructed image I72, and the reconstructed image I73 to the medical processing device 20 via the network NW.

Next, the processing function 24a in the medical processing apparatus 20 discriminates the reconstructed image I71, the reconstructed image I72, and the reconstructed image I73 with three types of reference substances. In addition, the processing function 24a generates an image showing the result of substance discrimination. For example, the processing function 24a generates a substance discrimination image for each reference substance, a virtual monochromatic X-ray image at a predetermined energy, a density image, an effective atomic number image, and the like.

Alternatively, the control function 144c transmits the projection data set corresponding to the energy E71, the projection data set corresponding to the energy E72, and the projection data set corresponding to the energy E73 to the medical processing apparatus 20 via the network NW. Next, the processing function 24a in the medical processing apparatus 20 reconstructs the reconstructed image I71 from the projection data set corresponding to the energy E71. In addition, the processing function 24a reconstructs the reconstructed image I72 from the projection data set corresponding to the energy E72. Further, the processing function 24a reconstructs the reconstructed image I73 from the projection data set corresponding to the energy E73. Next, the processing function 24a discriminates the reconstructed image I71, the reconstructed image I72, and the reconstructed image I73 with three types of reference substances, and generates an image showing the result of the substance discrimination. Although it has been described that the substance discrimination is performed at the stage of the reconstructed image, the processing function 24a may perform the substance discrimination at the stage of the projection data set.

Then, the control function 24b causes the display 22 to display an image showing the result of the substance discrimination generated by the processing function 24a. Alternatively, the control function 24b transmits an image showing the result of substance discrimination to the X-ray CT system 10. In this case, the control function 144c in the X-ray CT system 10 causes the display 142 to display an image showing the result of substance discrimination.

The term "processor" used in the above description refers to, for example, a CPU, a GPU (Graphics Processing Unit), an integrated circuit for a specific application (Application Specific Integrated Circuit: ASIC), a programmable logic device (for example, a simple programmable logic device (for example)). It means a circuit such as a Simple Programmable Logical Device (SPLD), a composite programmable logic device (Complex Programmable Logic Device: CPLD), and a field programmable gate array (Field Programmable Gate Array: FPGA). The processor realizes the function by reading and executing the program stored in the memory 141 or the memory 21.

Note that, in FIG. 1, a single memory 141 has been described as storing a program corresponding to each processing function of the processing circuit 144. Further, in FIG. 6, it has been described that a single memory 21 stores a program corresponding to each processing function of the processing circuit 24. However, the embodiment is not limited to this. For example, a plurality of memories 141 may be distributed and arranged, and the processing circuit 144 may be configured to read a corresponding program from the individual memories 141. Similarly, a plurality of memories 21 may be distributed and arranged, and the processing circuit 24 may be configured to read a corresponding program from the individual memories 21. Further, instead of storing the program in the memory 141 or the memory 21, the program may be directly incorporated in the circuit of the processor. In this case, the processor realizes the function by reading and executing the program embedded in the circuit.

Each component of each device according to the above-described embodiment is a functional concept, and does not necessarily have to be physically configured as shown in the figure. That is, the specific form of distribution / integration of each device is not limited to the one shown in the figure, and all or part of the device is functionally or physically distributed in arbitrary units according to various loads and usage conditions. It can be integrated and configured. Further, each processing function performed by each device may be realized by a CPU and a program analyzed and executed by the CPU, or may be realized as hardware by wired logic.

Further, the processing method described in the above-described embodiment can be realized by executing a processing program prepared in advance on a computer such as a personal computer or a workstation. This processing program can be distributed via a network such as the Internet. Further, this processing program is recorded on a non-transient recording medium such as a hard disk, flexible disk (FD), CD-ROM, MO, or DVD that can be read by a computer, and is executed by being read from the recording medium by the computer. You can also do it.

According to at least one embodiment described above, the feasibility of substance discrimination based on three or more kinds of reference substances can be improved.

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.

1 Medical information processing system 10 X-ray CT system 110 Mount device 111 X-ray tube 112 X-ray detector 113 Rotating frame 114 X-ray high voltage device 115 Control device 116 Wedge 117 Collimeter 118 DAS
130 Sleeper device 140 Console device 144 Processing circuit 144a Scan function 144b Processing function 144c Control function 20 Medical processing device 24 Processing circuit 24a Processing function 24b Control function

Claims (17)

A first scan is performed on the subject to collect a first projection data set corresponding to the first X-ray energy, and a second X-ray energy corresponding to a second X-ray energy different from the first X-ray energy is performed. A second scan that collects the two projection data sets and the third projection data set corresponding to the first X-ray energy and the third X-ray energy different from the second X-ray energy substantially simultaneously. And the scanning part that executes
An X-ray CT system including a first projection data set, a second projection data set, and a processing unit that discriminates substances with three or more kinds of reference substances based on the third projection data set. The X-ray CT system according to claim 1, wherein the first X-ray energy is larger or smaller than both the second X-ray energy and the third X-ray energy. The X-ray CT system according to claim 1, wherein the first X-ray energy is energy between the second X-ray energy and the third X-ray energy. The X-ray CT system according to any one of claims 1 to 3, wherein the scanning unit executes the first scan before the second scan. The X-ray CT system according to claim 4, wherein the scanning unit executes the second scanning on a scanning range set in a reference image generated based on the first projection data set. The X-ray CT system according to any one of claims 1 to 3, wherein the scanning unit executes the second scan before the first scan. The scanning unit performs the first scan on a scan range set in a reference image generated based on at least one of the second projection data set and the third projection data set. 6. The X-ray CT system according to 6. By executing the first scan, the scanning unit corresponds to the first X-ray energy, the second X-ray energy, and the fourth X-ray energy different from the third X-ray energy. The fourth projection data set and the first projection data set to be collected are collected substantially at the same time.
The processing unit discriminates substances with four or more kinds of reference substances based on the first projection data set, the second projection data set, the third projection data set, and the fourth projection data set. Item 6. The X-ray CT system according to any one of Items 1 to 7. The scanning unit executes the second scan by changing the X-ray energy between the second X-ray energy and the third X-ray energy for each one or a plurality of views. The X-ray CT system according to any one of claims 1 to 8. The scanning unit irradiates the X-ray of the second X-ray energy from the first X-ray tube and irradiates the X-ray of the third X-ray energy from the second X-ray tube. The X-ray CT system according to any one of claims 1 to 8, wherein the second scan is performed. The scanning unit has a laminated X-ray detection having a first layer for detecting X-rays of the second X-ray energy and a second layer for detecting X-rays of the third X-ray energy. The X-ray CT system according to any one of claims 1 to 8, wherein the second scan is performed using a device. The scanning unit uses a photon counting type X-ray detector to count the number of X-ray photons of the second X-ray energy and the number of X-ray photons of the third X-ray energy, respectively. The X-ray CT system according to any one of claims 1 to 8, wherein the second scan is performed. The scanning unit includes a first X-ray filter that attenuates transmitted X-rays to the second X-ray energy, and a second X-ray filter that attenuates transmitted X-rays to the third X-ray energy. The X-ray CT system according to any one of claims 1 to 8, wherein the second scan is performed using the above. The scanning unit attenuates a part of the X-rays applied to the subject by using an X-ray filter that attenuates the transmitted X-rays from the second X-ray energy to the third X-ray energy. The X-ray CT system according to any one of claims 1 to 8, wherein the second scan is performed. The X-ray CT according to any one of claims 1 to 14, wherein the scanning unit executes the first scan and the second scan in synchronization with each other according to the heartbeat or respiration cycle of the subject. system. The processing unit aligns the first projection data set with the second projection data set and the third projection data set, and after the alignment, the first projection data set, the second projection data set, and the processing unit The X-ray CT system according to any one of claims 1 to 15, wherein material discrimination is performed based on the third projection data set. The first projection data set corresponding to the first X-ray energy collected by performing the first scan on the subject and the said-mentioned collected by performing the second scan on the subject. The second projection data set corresponding to the second X-ray energy different from the first X-ray energy and the second projection data set collected substantially simultaneously with the second projection data set by performing the second scan. A processing unit that discriminates substances from three or more types of reference substances based on a first X-ray energy and a third projection data set corresponding to a third X-ray energy different from the second X-ray energy. A medical processing device equipped with.

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