JP7321846B2 - X-ray CT system and medical processing equipment - Google Patents

Description

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

There is a technique for performing substance discrimination of a target object using a plurality of reference substances based on projection data corresponding to two or more types of X-ray energies acquired by an X-ray CT (Computed Tomography) scanner, and displaying the result as an image. . When using two types of X-ray energy, this technique is called Dual Energy (DE), and material discrimination is possible using two types of reference materials.

For example, dual energy technology can distinguish between kidney stones, fat, soft tissue, and bone in a subject's body. Further, for example, according to the Dual Energy technology, it is possible to determine whether kidney stones in the subject's body are calcium-type stones or uric acid-type stones.

Here, scanning is not always performed with dual energy, and scanning with single energy is often performed. In addition, it may be determined that dual-energy material discrimination is necessary based on the results of a single-energy scan. For example, if a single-energy scan reveals the presence of a kidney stone and dual-energy material discrimination is required to determine whether the kidney stone is calcium-type or uric acid-type. There is Here, if a dual energy scan were to be executed again, the burden on the subject would be heavy, and the amount of radiation exposure would also increase.

JP 2018-42604 A JP 2017-518844 A JP 2007-268274 A

The problem to be solved by the present invention is to perform material discrimination without additional scanning.

An X-ray CT system according to an embodiment includes a scanning section and a processing section. The scanning unit performs a first scan for acquiring a first data set corresponding to a first X-ray energy by irradiating a first range along the body axis direction of the subject with X-rays, After one scan, a second range narrower than the first range along the body axis direction is irradiated with X-rays to obtain a second X-ray energy different from the first X-ray energy. A second scan is performed that collects a corresponding second data set. The processing unit performs substance discrimination using a plurality of reference substances based on the first data set and the second data set.

FIG. 1 is a block diagram showing an example configuration of an X-ray CT system according to the first embodiment. FIG. 2 is a diagram showing an example of processing of the X-ray CT system according to the first embodiment. FIG. 3 is a flowchart for explaining a series of processing flows of the X-ray CT system according to the first embodiment. FIG. 4 is a block diagram showing an example of the configuration of a medical information processing system according to the second embodiment.

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

(First embodiment)
First, the configuration of an 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 configuration of an X-ray CT system 10 according to the first embodiment. As shown in FIG. 1 , the X-ray CT system 10 has a gantry device 110 , a bed device 130 and a console device 140 . The X-ray CT system 10 is also called an X-ray CT device or an X-ray CT scanner.

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

The gantry device 110 has 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 with thermoelectrons. The X-ray tube 111 emits thermal electrons from the cathode to the anode by applying a high voltage from the X-ray high-voltage device 114, thereby generating X-rays to irradiate the subject P. As shown in FIG.

The X-ray detector 112 detects X-rays emitted 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 detector element arrays in which a plurality of detector elements are arranged in the channel direction (channel direction) along one circular 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 detector element arrays in which a plurality of detector elements are arranged in the channel direction are arranged in the column direction (slice direction, row direction).

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

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 also support the X-ray high voltage device 114, the wedge 116, the collimator 117, the DAS 118, and the like. Additionally, the rotating frame 113 can also support various additional configurations not shown in FIG. Below, in the gantry device 110, the rotating frame 113 and the portion that rotates together with the rotating frame 113 are also referred to as rotating parts.

The X-ray high-voltage device 114 has electric circuits such as a transformer and a rectifier, and includes a high-voltage generator that generates a high voltage to be applied to the X-ray tube 111 and an X-ray that the X-ray tube 111 generates. and an X-ray controller for controlling the output voltage according to. The high voltage generator may be of 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 has a processing circuit including a CPU (Central Processing Unit) and the like, and drive mechanisms such as motors and actuators. The control device 115 receives an input signal from the input interface 143 and controls the operation of the gantry device 110 and the bed 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 bed 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 input inclination angle (tilt angle) information as control for tilting the gantry device 110 . Note that the control device 115 may be provided in the gantry device 110 or may be provided in the console device 140 .

Wedge 116 is an X-ray filter for adjusting the dose of X-rays emitted from 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 down the irradiation range of the X-rays transmitted through the wedge 116, and a slit is formed by combining a plurality of lead plates or the like. Note that the collimator 117 may also be called an X-ray diaphragm. 1 shows the case where the wedge 116 is arranged between the X-ray tube 111 and the collimator 117, the case where the collimator 117 is arranged between the X-ray tube 111 and the wedge 116 good too. In this case, the wedge 116 transmits and attenuates X-rays emitted from the X-ray tube 111 and whose irradiation range is limited by the collimator 117 .

The DAS 118 collects X-ray signals detected by each detection element of the X-ray detector 112 . For example, the DAS 118 has an amplifier that amplifies the electrical signal output from each detection element, and an A/D converter that converts the electrical signal into a digital signal to generate detection data. DAS 118 is implemented 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 to a non-rotating portion of the gantry 110 (for example, a fixed frame, etc.) by optical communication. (not shown) is transmitted to a receiver having a photodiode and transferred to the console device 140 . Here, the non-rotating portion is, for example, a fixed frame or the like 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 employed. I don't mind if you hire me.

The bed device 130 is a device for placing and moving the subject P to be scanned, and has a base 131 , a bed driving device 132 , a top board 133 and a support frame 134 . The base 131 is a housing that supports the support frame 134 so as to be vertically movable. The bed drive device 132 is a drive mechanism that moves the table 133 on which the subject P is placed in the longitudinal direction of the table 133, and includes a motor, an actuator, and the like. A top plate 133 provided on the upper surface of the support frame 134 is a plate on which the subject P is placed. Note that the bed driving device 132 may move the support frame 134 in addition to the top plate 133 in the longitudinal direction of the top plate 133 .

Console device 140 has memory 141 , display 142 , input interface 143 , and processing circuitry 144 . Although the console device 140 is described as being separate from the gantry device 110 , the console device 140 or a part of each component of the console device 140 may be included in the gantry device 110 .

The memory 141 is realized by, for example, a RAM (Random Access Memory), a semiconductor memory device such as a flash memory, a hard disk, an optical disk, or the like. For example, the memory 141 stores various data collected by executing a scan on the subject P. FIG. Also, for example, the memory 141 stores programs for the circuits included in the X-ray CT system 10 to implement their functions. Note that 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 CT images for display generated by the processing circuitry 144 and the results of material discrimination. Further, for example, the display 142 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 of a desktop type, or may be configured by a tablet terminal or the like capable of wireless communication with the main body of the console device 140 .

The input interface 143 accepts various input operations from the user, converts the accepted input operations into electrical signals, and outputs the electrical signals to the processing circuit 144 . For example, the input interface 143 receives, from the user, reconstruction conditions for reconstructing CT image data, image processing conditions for generating a CT image for display from CT image data, 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 that performs input operations by touching an operation surface, a touch screen that integrates a display screen and a touch pad, and an optical sensor. It is realized by the used non-contact input circuit, voice input circuit, or the like. Note that the input interface 143 may be provided in the gantry device 110 . Also, the input interface 143 may be composed of a tablet terminal or the like capable of wireless communication with the main body of the console device 140 . Also, the input interface 143 is not limited to having physical operation parts such as a mouse and a keyboard. For example, an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the console device 140 and outputs this electrical signal to the processing circuit 144 is an example of the input interface 143. included.

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

For example, the processing circuit 144 scans the subject P by reading out from the memory 141 and executing a program corresponding to the scan function 144a. For example, the scan function 144a performs various scans such as positioning imaging and main scan on the subject P. FIG.

Here, positioning imaging may be performed two-dimensionally or three-dimensionally. In this embodiment, as an example, a case of performing two-dimensional positioning imaging will be described. In this case, the scan function 144a rotates at least one of the X-ray focus position and the subject P in the body axis direction of the subject P (shown in FIG. 1) without rotating the X-ray focus position around the subject P. Positioning imaging is performed while moving along the Z-axis direction).

For example, the scanning function 144a fixes the position of the X-ray tube 111 at a predetermined rotation angle, and irradiates the subject P with X-rays from the X-ray tube 111 while moving the tabletop 133 in the Z-axis direction. . In addition, while positioning imaging is performed by the scanning function 144a, the DAS 118 collects X-ray signals from each detection element in the X-ray detector 112 and generates detection data. Also, the scan function 144 a preprocesses the detection data output from the DAS 118 . For example, the scanning function 144a performs preprocessing such as logarithmic conversion processing, offset correction processing, inter-channel sensitivity correction processing, and beam hardening correction on the detection data output from the DAS 118 . Data after preprocessing is also referred to as raw data. Further, detection data before preprocessing and raw data after preprocessing are collectively referred to as projection data.

That is, the scanning function 144a fixes the position of the X-ray tube 111 at a predetermined rotation angle, and irradiates the subject P with X-rays from the X-ray tube 111 while moving the tabletop 133 in the Z-axis direction. Thus, projection data are acquired for each of a plurality of positions in the body axis direction of the subject P. FIG. In the following, a plurality of pieces of projection data are also collectively referred to as a projection data set. That is, the scan function 144a acquires projection data sets by performing positional imaging.

Further, the processing circuit 144 reads a program corresponding to the processing function 144b from the memory 141 and executes it to generate image data based on the scanning result. For example, processing function 144b generates localization image data based on projection data sets acquired from localization imaging. Note that the positioning image data may also be called scanogram image data or scout image data.

Further, the main scan may be performed by, for example, a conventional scan method, a helical scan method, or a step-and-shoot method.

When the main scan is performed by the conventional scan method, the scan function 144a rotates the X-ray focal position around the object P without moving the X-ray focal position and the object P along the body axis direction. Execute the main scan while For example, the scanning function 144a irradiates the subject P with X-rays from the X-ray tube 111 while rotating the X-ray tube 111 around the subject P with the tabletop 133 stopped.

Further, when the main scan is performed by the helical scan method, the scan function 144a moves the focal position of the X-rays and the subject P along the body axis direction, and moves the focal position of the X-rays around the subject P. Execute the main scan while rotating with . For example, the scan function 144a moves the tabletop 133 in the Z-axis direction, rotates the X-ray tube 111 around the subject P, and irradiates the subject P with X-rays from the X-ray tube 111. .

When the main scan is executed by the step-and-shoot method, the scan function 144a first moves the focal position of the X-ray around the object P without moving the focal position of the X-ray and the object P along the body axis direction. Execute the main scan while rotating with . For example, the scanning function 144a irradiates the subject P with X-rays from the X-ray tube 111 while rotating the X-ray tube 111 around the subject P with the tabletop 133 stopped. Next, the scan function 144a moves the tabletop 133 in the Z-axis direction while the X-ray irradiation from the X-ray tube 111 is stopped. Then, the scanning function 144a causes the X-ray tube 111 to irradiate the subject P again with X-rays while rotating the X-ray tube 111 around the subject P with the top plate 133 stopped.

While the scan function 144a performs the main scan, the DAS 118 collects X-ray signals from each detector element in the X-ray detector 112 and generates detection data. The scanning function 144a also performs preprocessing such as logarithmic conversion processing, offset correction processing, inter-channel sensitivity correction processing, and beam hardening correction on the detection data output from the DAS 118 .

That is, the scan function 144a irradiates the subject P with X-rays while rotating the focal position of the X-rays around the subject P, thereby acquiring projection data for each of a plurality of irradiation directions (views). That is, the scan function 144a acquires projection data sets by performing a main scan.

The processing function 144b also generates CT image data (volume data) based on the projection data set acquired by the main scan. For example, the processing function 144b generates CT image data by performing reconstruction processing using a filtered back projection method, an iterative reconstruction method, an iterative applied reconstruction method, etc. based on the projection data set. . The processing function 144b can also perform reconstruction processing by AI (Artificial Intelligence) to generate CT image data. For example, the processing function 144b generates CT image data by a DLR (Deep Learning Reconstruction) method.

Further, the processing function 144b performs substance discrimination using a plurality of reference substances based on the projection data set acquired by positioning imaging and the projection data set acquired by main scanning. For example, when the presence of a disease in the subject P is clarified based on the projection data set acquired by the main scan, the processing function 144b uses the projection data set acquired by positioning imaging and the Material discrimination is performed based on the projection data set acquired by the main scan. Substance discrimination by the processing function 144b will be described later.

The processing circuit 144 also controls the display on the display 142 by reading out a program corresponding to the control function 144c from the memory 141 and executing it. For example, the control function 144c converts positioning image data and CT image data generated by the processing function 144b into images for display by a known method. For example, the control function 144c converts CT image data into tomographic image data of an arbitrary cross section, three-dimensional image data, or the like, based on an input operation received from the user via the input interface 143, or the like. Then, the control function 144c causes the display 142 to display the converted display image. In addition, the control function 144c causes the display 142 to display the result of substance discrimination by the processing function 144b. Also, the control function 144c transmits various data via the network. For example, the control function 144c transmits positioning image data and CT image data generated by the processing function 144b 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 computer-executable program. The processing circuit 144 is a processor that implements a function corresponding to each program by reading and executing the program from the memory 141 . In other words, the processing circuit 144 with the program read has the function corresponding to the read program.

In FIG. 1, the scan function 144a, the processing function 144b, and the control function 144c are realized by the single processing circuit 144, but the processing circuit 144 may be configured by combining a plurality of independent processors. , each processor may implement the function by executing a program. Moreover, each processing function of the processing circuit 144 may be appropriately distributed or integrated in a single or a plurality of processing circuits and implemented.

Also, the processing circuit 144 may implement its functions using a processor of an external device connected via a network. For example, the processing circuit 144 reads and executes a program corresponding to each function from the memory 141, and uses a server group (cloud) connected to the X-ray CT system 10 via a network as computational resources. Each function shown in FIG. 1 is implemented.

The configuration example of the X-ray CT system 10 has been described above. Processing performed by the X-ray CT system 10 will be described in detail below with reference to FIG. FIG. 2 is a diagram showing an example of processing of the X-ray CT system 10 according to the first embodiment.

First, the scan function 144a executes scan A11. Specifically, as shown in FIG. 2, the scan function 144a moves the X-ray focal position relative to the object P without rotating the X-ray focal position around the object P. while the subject P is irradiated with X-rays of energy E11. Thereby, the scan function 144a irradiates the range R1 along the body axis direction of the subject P with X-rays and acquires the projection data set B11 corresponding to the energy E11. For example, the scanning function 144a fixes the position of the X-ray tube 111 at a predetermined rotation angle, moves the tabletop 133 in the Z-axis direction, and acquires the projection data set B11. The processing function 144b also generates two-dimensional image data C11 based on the projection data set B11 acquired by the scan A11.

Scan A11 is an example of the first scan. Also, the range R1 is an example of the first range. Also, the projection data set B11 is an example of a first projection data set. Also, the energy E11 is an example of the first X-ray energy. Also, the image data C11 is an example of the first image data.

Next, the control function 144c causes the display 142 to display the reference image based on the image data C11. Further, the control function 144c receives an input operation from the user who referred to the reference image, thereby setting the range R2, which is the scan range of the scan A12. Scan A12 is an example of the second scan. Also, the range R2 is an example of a second range.

That is, scan A11 is positioning imaging for setting range R2, which is the scan range of scan A12. Therefore, it is preferable that the range R1 of the scan A11 be set to a relatively wide range so as to include the organs and the like to be diagnosed. Also, since the range R2 is set in the range R1, it is normally narrower than the range R1 as shown in FIG.

Next, the scan function 144a executes a scan A12 on the range R2 set in the reference image. Specifically, the scan function 144a irradiates the subject P with X-rays of energy E12 while rotating the focal position of the X-rays around the subject P, as shown in FIG. Thereby, the scan function 144a irradiates the range R2 along the body axis direction of the subject P with X-rays and acquires the projection data set B12 corresponding to the energy E12. For example, the scanning function 144a acquires the projection data set B12 by performing conventional scanning, helical scanning, and step-and-shoot scanning.

Note that the projection data set B12 is an example of a second projection data set. Also, the energy E12 is an example of the second X-ray energy. The energy E12 is energy different from the energy E11.

The processing function 144b also generates three-dimensional image data C12 based on the projection data set B12 acquired by the scan A12. Note that the image data C12 is an example of the second image data. For example, the processing function 144b performs reconstruction processing such as a filtered backprojection method, an iterative reconstruction method, an iterative approximation applied reconstruction method, and a DLR method based on the projection data set B12 to obtain a three-dimensional image. Reconstruct data C12. That is, scan A12 is the main scan for acquiring CT image data (volume data).

Note that the scan function 144a may synchronize the scan A11 and the scan A12 according to the heartbeat or respiration cycle of the subject P and execute them. That is, the scan function 144a may synchronize and execute the scans A11 and A12 so that there is no positional deviation between the scans A11 and A12 due to periodic motion due to heartbeat or respiration.

For example, the scan function 144a acquires the electrocardiographic waveform of the subject P in parallel with scan A11 and scan A12. For example, the scanning function 144a obtains an electrocardiographic waveform of the subject P using an electrocardiograph attached to the subject P. FIG. Then, the scan function 144a executes scan A12 so that the phase of the electrocardiogram waveform in scan A12 matches the phase of the electrocardiogram waveform in scan A11.

Also, for example, the scan function 144a acquires the respiratory waveform of the subject P in parallel with the scans A11 and A12. For example, the scan function 144a acquires a respiratory waveform of the subject P using a respiratory sensor. For example, the scan function 144a acquires a respiratory waveform using a laser generator and a light receiver as a respiratory sensor. Specifically, the scan function 144a processes the signal of reflected light from the abdominal surface of the subject P, and based on the time from laser irradiation to reflected light reception or the phase change of the reflected light signal, the laser generator and the A respiratory waveform is obtained by repeatedly calculating the distance to the abdominal surface of the subject in real time. Note that the example of the respiratory sensor is not limited to this, and the scanning function 144a detects a respiratory waveform using, for example, a pressure sensor attached to the abdomen of the subject P, an optical camera that images the subject P, or the like. It does not matter if it is acquired. Then, the scan function 144a executes the scan A12 so that the phase of the respiratory waveform in the scan A12 matches the respiratory waveform in the scan A11.

Here, a user such as a doctor can make a diagnosis based on the image data C12 collected by the scan A12. For example, first, the control function 144c generates a display image by executing rendering processing on the image data C12. 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 image data C12 by a cross-sectional reconstruction method (MPR: Multi Planar Reconstruction). Further, as another example of rendering processing, a two-dimensional image reflecting three-dimensional information is generated from the image data C12 by volume rendering processing or maximum intensity projection (MIP). processing to be performed. Then, the control function 144c causes the display 142 to display the display image generated by the rendering process. Further, the user can diagnose the subject P while referring to the display image.

Here, as a result of diagnosis based on the image data C12, material discrimination processing may be required. For example, the diagnosis may reveal the presence of a kidney stone, and it may be determined that a material discrimination process is required to determine whether the kidney stone is of the calcium type or the uric acid type.

However, if the dual energy scan is additionally performed after the scan A12 is completed, the exposure dose of the subject P will increase. As dual energy scanning methods, various methods such as kV switching, dual layer, dual source, and split are known. is the amount of radiation exposure. In addition, if the dual energy scan is to be performed again for reexamination, the subject P will be burdened in terms of time and physical strength.

Processing function 144b then performs material discrimination without resorting to additional scans. Specifically, processing function 144b performs material discrimination with a plurality of reference materials based on projection data set B11 and projection data set B12 already acquired by scan A11 and scan A12.

More specifically, the processing function 144b first identifies the target region Q1 where the disease of the subject P is located based on the image data C12. That is, the processing function 144b segments the region corresponding to the disease in the image data C12 as the target region Q1. For example, the processing function 144b identifies the target area Q1 by receiving an input operation from the user who refers to the display image based on the image data C12. Also, for example, the processing function 144b automatically identifies the target region Q1 by analyzing the image data C12 and extracting the disease.

Next, the processing function 144b generates two-dimensional image data C13 based on the image data C12. Here, the image data C13 is two-dimensional image data corresponding to the X-ray irradiation direction of the scan A11. Also, the image data C13 is an example of the third image data.

For example, the processing function 144b generates the image data C13 by forward projecting the image data C12 in the X-ray irradiation direction in the scan A11. Further, for example, the processing function 144b generates a plurality of MPR images perpendicular to the X-ray irradiation direction in the scan A11 based on the image data C12, and synthesizes these MPR images to generate the image data C13. . A region of the image data C13 corresponding to the target region Q1 specified in the image data C12 is referred to as a region Q2.

Further, the processing function 144b identifies a region Q3 in the image data C11 corresponding to the target region Q1 identified in the image data C12. For example, the processing function 144b identifies the area Q3 by aligning the image data C11 and the image data C12 and identifying the area corresponding to the target area Q1 of the image data C12 in the image data C11. Further, for example, the processing function 144b identifies the area Q3 by aligning the image data C11 and the image data C13 and identifying the area corresponding to the area Q2 of the image data C13 in the image data C11.

When specifying the target area Q1, area Q2, and area Q3, the processing function 144b may perform processing such as denoising in advance on at least one of the image data C11, image data C12, and image data C13. Further, the processing function 144b may use AI to perform part or all of the alignment process, the process of specifying the target area Q1, the area Q2, and the area Q3, and the process such as denoising.

Then, the processing function 144b performs material discrimination based on the image data C11 and the image data C13. That is, the image data C11 acquired by the scan A11 is data of energy E11, and the image data C13 acquired by scan A12 is data of energy E12. Based on and, material discrimination by two types of reference materials can be performed.

For example, the processing function 144b can determine the X-ray attenuation ratio at the location of the kidney stone of the subject P based on the image data C11 and the image data C13 acquired at different energies. That is, the processing function 144b can obtain the ratio of the X-ray attenuation in the region Q3 of the image data C11 acquired at the energy E11 and the X-ray attenuation in the region Q2 of the image data C13 acquired at the energy E12. can. Then, the processing function 144b can determine whether the kidney calculus of the subject P is a calcium-type calculus or a uric acid-type calculus based on the X-ray attenuation ratio.

In addition, the control function 144c causes the display 142 to display the result of substance discrimination by the processing function 144b. For example, the control function 144c causes the display 142 to display information indicating whether the kidney stone of the subject P is a calcium-type stone or a uric acid-type stone.

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

Steps S101 and S106 correspond to the scan function 144a. Steps S102, S107, S108, S109, S110 and S111 correspond to processing function 144b. Steps S103, S104, S105 and S112 correspond to control function 144c.

First, processing circuit 144 performs scan A11 on subject P and acquires projection data set B11 corresponding to energy E11 (step S101). Next, processing circuitry 144 generates image data C11 based on projection data set B11 (step S102). Next, the processing circuit 144 generates a reference image based on the image data C11 (step S103), and causes the display 142 to display the generated reference image (step S104).

Here, the processing circuit 144 determines whether or not the range R2, which is the scanning range of the scan A12, has been set by the user who referred to the reference image (step S105). state (No at step S105). On the other hand, if the scan range has been set (Yes at step S105), processing circuitry 144 performs scan A12 on the scan range set in the reference image to acquire projection data set B12 corresponding to energy E12. (Step S106). Processing circuitry 144 then generates image data C12 based on projection data set B12 (step S107).

Next, the processing circuit 144 identifies the target region Q1 where the disease of the subject P is located in the image data C12 (step S108). Next, the processing circuit 144 generates two-dimensional image data C13 based on the three-dimensional image data C12 (step S109). In addition, the processing circuit 144 identifies a region Q3 corresponding to the target region Q1 in the image data C11 (step S110). The order in which steps S109 and S110 are performed is arbitrary, and they may be performed in parallel.

Next, processing circuit 144 performs material discrimination based on image data C11 corresponding to energy E11 and image data C13 corresponding to energy E12 (step S111). Then, the processing circuit 144 causes the display 142 to display the material discrimination result (step S112), and ends the process.

As an example of substance discrimination, the process of determining whether the kidney calculus of the subject P is a calcium-type calculus or a uric acid-type calculus has been described so far. However, embodiments are not so limited. For example, the processing function 144b can also calculate the mixing amount and mixing ratio of the two reference materials at each position based on the image data C11 and the image data C13 acquired at different energies.

Specifically, the processing function 144b obtains the distribution of the linear attenuation coefficients for each of the image data C11 and the image data C13, and solves the following simultaneous equations (1) for each position (each pixel) of the linear attenuation coefficients. Thus, the mixing amount and mixing ratio of the two reference substances at each position are calculated.

Here, “μ(E1)” indicates the linear attenuation coefficient at each position at the monochromatic X-ray energy “E1”, and “μ(E2)” indicates the linear attenuation coefficient at each position at the monochromatic X-ray energy “E2”. . "μ _α (E)" indicates the linear attenuation coefficient of the reference material α, and "μ _β (E)" indicates the linear attenuation coefficient of the reference material β. Further, "c _α " indicates the mixed amount of the reference substance α, and "c _β " indicates the mixed amount of the reference substance β. The linear attenuation coefficient for each energy of each reference substance is known. For example, the processing function 144b substitutes the energy E11 for "E1" and the energy E12 for "E2" to solve the simultaneous equations of formula (1), thereby obtaining Perform material discrimination.

Processing function 144b then generates an image showing the results of the material discrimination. For example, processing function 144b generates a material discrimination image for each reference material. For example, the processing function 144b generates a material-distinguished image in which the reference material α is emphasized and a material-discrimination image in which the reference material β is emphasized. The processing function 144b also uses a plurality of material-discriminating images generated for each reference material to perform weighting calculation processing based on the mixing ratio of each reference material, thereby obtaining a virtual monochromatic X-ray image (monochromatic X-ray image) at a predetermined energy. images), density images, effective atomic number images, and various other images can also be generated. In addition, the control function 144c causes the display 142 to display an image showing the results of these material discriminations.

As described above, according to the first embodiment, the scanning function 144a acquires the projection data set B11 corresponding to the energy E11 by irradiating the range R1 along the body axis direction of the subject P with X-rays. scan A11 is executed. Further, after the scan A11, the scan function 144a executes a scan A12 for acquiring a projection data set B12 corresponding to the energy E12 by irradiating the range R2 along the body axis direction of the subject P with X-rays. do. Processing function 144b also performs material discrimination based on projection data set B11 corresponding to energy E11 and projection data set B12 corresponding to energy E12. Therefore, the X-ray CT system 10 according to the first embodiment can perform material discrimination without using additional scans other than scans A11 and A12.

Also, the X-ray CT system 10 can set the range R2 in the scan A12 based on the result of the scan A11 and perform material discrimination. That is, the X-ray CT system 10 can make the exposure of the subject P by the scan A11 more meaningful.

(Second embodiment)
Now, although the first embodiment has been described so far, it may be implemented in various different forms other than the above-described embodiment.

For example, it has been described above that the user sets the range R2, which is the scan range of the scan A12, but the embodiment is not limited to this. For example, the control function 144c may automatically set the range R2 by analyzing the image data C11 or a reference image generated based on the image data C11 and extracting an organ or the like to be diagnosed.

Further, in the above-described embodiment, the case where positioning imaging is performed in two dimensions has been described. However, the embodiment is not limited to this, and the X-ray CT system 10 may perform positioning imaging in three dimensions.

For example, the scan function 144a first performs a three-dimensional scan A21 instead of the scan A11 to acquire a projection data set B21. Specifically, the scan function 144a irradiates the subject P with X-rays of energy E11 while rotating the focal position of the X-rays around the subject P. FIG. Thereby, the scanning function 144a irradiates the range R1 along the body axis direction of the subject P with X-rays and acquires the projection data set B21 corresponding to the energy E11. For example, the scanning function 144a acquires the projection data set B21 by performing conventional scanning, helical scanning, and step-and-shoot scanning. Note that the projection data set B21 is an example of the first data set.

Next, processing function 144b generates three-dimensional image data C21 based on projection data set B21 acquired by scan A21. For example, the processing function 144b performs reconstruction processing such as a filtered back projection method, an iterative reconstruction method, an iterative approximation applied reconstruction method, and a DLR method based on the projection data set B21 to obtain a three-dimensional image. Reconstruct data C21.

Next, the control function 144c sets the range R2, which is the scanning range of the scan A12, based on the image data C21. Scan function 144a then performs scan A12 over range R2 and acquires projection data set B12 corresponding to energy E12. Processing function 144b then generates three-dimensional image data C12 based on projection data set B12 acquired by scan A12.

Next, the processing function 144b generates two-dimensional image data C22 based on the three-dimensional image data C21, and generates two-dimensional image data C13 based on the three-dimensional image data C12. For example, the processing function 144b generates the image data C22 and the image data C13 by forward projecting the image data C21 and the image data C12 in the same direction. Further, for example, the processing function 144b generates a plurality of MPR images in the same direction for each of the image data C21 and the image data C12, and combines the generated MPR images to obtain the image data C22 and the image data C13. to generate

Then, the processing function 144b performs material discrimination based on the image data C22 and the image data C13. That is, the image data C22 acquired by the scan A21 is data of energy E11, and the image data C13 acquired by the scan A12 is data of energy E12. Based on and, material discrimination by two types of reference materials can be performed.

The processing function 144b may perform material discrimination based on the image data C21 and the image data C12. That is, the processing function 144b may perform material discrimination based on the three-dimensional image data C21 acquired by the scan A21 and the three-dimensional image data C12 acquired by the scan A12.

Also, although the X-ray CT system 10 has been described as performing material discrimination, the embodiments are not limited to this. For example, material discrimination may be performed in another device different from X-ray CT system 10 . This point will be described below by taking the medical information processing system 1 shown in FIG. 4 as an example. FIG. 4 is a block diagram showing an example of the configuration of the medical information processing system 1 according to the second embodiment. The medical information processing system 1 includes an X-ray CT system 10 and a medical processing apparatus 20 that performs material discrimination.

As shown in FIG. 4, the X-ray CT system 10 and the medical processing apparatus 20 are interconnected via a network NW. Here, the location where the X-ray CT system 10 and the medical processing apparatus 20 are installed is arbitrary as long as they can be connected via the network NW. For example, the medical processing apparatus 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 closed local network within the hospital, or may be a network via the Internet. Moreover, although one X-ray CT system 10 is shown in FIG. 4 , the medical information processing system 1 may include a plurality of X-ray CT systems 10 .

The medical processing apparatus 20 is implemented by computer equipment such as a workstation. For example, the medical processing device 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 implemented by, for example, a RAM, a semiconductor memory device such as 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 . In addition, for example, the memory 21 stores programs for circuits included in the medical processing apparatus 20 to implement their functions. Note that the memory 21 may be realized by a server group (cloud) connected to the medical processing apparatus 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 receiving various operations from the user. For example, display 22 is a liquid crystal display or a CRT display. The display 22 may be of a desktop type, or may be configured by a tablet terminal or the like capable of wireless communication with the main body of the medical processing apparatus 20 .

The input interface 23 receives various input operations from the user, converts the received input operations into electrical signals, and outputs the electrical signals to the processing circuit 24 . For example, the input interface 23 receives reconstruction conditions for reconstructing CT image data, image processing conditions for generating a CT image for display from CT image data, and the like from the user. For example, the input interface 23 includes a mouse, a keyboard, a trackball, a switch, a button, a joystick, a touch pad that performs input operations by touching an operation surface, a touch screen that integrates a display screen and a touch pad, and an optical sensor. It is realized by the used non-contact input circuit, voice input circuit, or the like. 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 apparatus 20 . Moreover, the input interface 23 is not limited to those having physical operation parts such as a mouse and a keyboard. For example, an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the medical processing apparatus 20 and outputs the electrical signal to the processing circuit 24 is an example of the input interface 23. include.

The processing circuitry 24 controls the overall operation of the medical processing apparatus 20 by executing processing functions 24a and control functions 24b. Note that the processing function 24a is an example of a processing unit. Processing by the processing circuit 24 will be described later.

In the medical processing apparatus 20 shown in FIG. 4, each processing function is stored in the memory 21 in the form of a computer-executable program. The processing circuit 24 is a processor that implements a function corresponding to each program by reading the program from the memory 21 and executing the program. In other words, the processing circuit 24 in a state where the program has been read has functions corresponding to the read program.

In FIG. 4, the processing function 24a and the control function 24b are realized by the single processing circuit 24, but the processing circuit 24 is configured by combining a plurality of independent processors, and each processor can be programmed. The function may be realized by executing Further, each processing function of the processing circuit 24 may be appropriately distributed or integrated in a single or a plurality of processing circuits and implemented.

Also, the processing circuit 24 may implement its functions using a processor of an external device connected via the network NW. For example, the processing circuit 24 reads out and executes a program corresponding to each function from the memory 21, and uses a server group (cloud) connected to the medical processing apparatus 20 via the network NW as computational resources. Each function shown in FIG. 4 is realized.

For example, first, the scanning function 144a in the X-ray CT system 10 irradiates a range R1 along the body axis direction of the subject P with X-rays without rotating the focal position of the X-rays around the subject P. Perform scan A11 at and acquire projection data set B11 corresponding to energy E11. Alternatively, the scanning function 144a executes a scan A21 by irradiating a range R1 along the body axis direction of the subject P with X-rays while rotating the focal position of the X-ray around the subject P, and the energy Acquire projection data set B21 corresponding to E11.

Further, the scanning function 144a executes the scan A12 by irradiating the range R2 along the body axis direction of the subject P with X-rays after the scan A11 or the scan A21, and the projection data set corresponding to the energy E12. Collect B12. Also, the control function 144c transmits the projection data set B11 or the projection data set B21 and the projection data set B12 to the medical processing apparatus 20 via the network NW.

Next, the processing function 24a in the medical processing apparatus 20 performs material discrimination using a plurality of reference materials based on the projection data set B11 or projection data set B21 and the projection data set B12.

For example, the processing function 24a generates two-dimensional image data C11 based on the projection data set B11. The processing function 24a also generates three-dimensional image data C12 based on the projection data set B12, and generates two-dimensional image data C13 based on the image data C12. Then, the processing function 24a performs material discrimination based on the image data C11 corresponding to the energy E11 and the image data C13 corresponding to the energy E12.

Alternatively, the processing function 24a generates three-dimensional image data C21 based on the projection data set B21, and generates two-dimensional image data C22 based on the image data C21. The processing function 24a also generates three-dimensional image data C12 based on the projection data set B12, and generates two-dimensional image data C13 based on the image data C12. Then, the processing function 24a performs material discrimination based on the image data C22 corresponding to the energy E11 and the image data C13 corresponding to the energy E12.

Alternatively, the processing function 24a generates three-dimensional image data C21 based on the projection data set B21. The processing function 24a also generates three-dimensional image data C12 based on the projection data set B12. Then, the processing function 24a performs material discrimination based on the image data C21 corresponding to the energy E11 and the image data C12 corresponding to the energy E12.

Then, the control function 24b causes the display 22 to display the result of material discrimination by the processing function 24a. For example, the control function 24b causes the display 22 to display information indicating whether the kidney calculus of the subject P is a calcium-type calculus or a uric acid-type calculus. Also, for example, the control function 24b causes the display 22 to display an image showing the material discrimination result generated by the processing function 24a.

Alternatively, the control function 24b sends the results of material discrimination by the processing function 24a to the X-ray CT system 10. FIG. In this case, the control function 144 c in the X-ray CT system 10 can cause the display 142 to display the result of material discrimination transmitted from the medical processing apparatus 20 .

The term "processor" used in the above description includes, for example, a CPU, a GPU (Graphics Processing Unit), an Application Specific Integrated Circuit (ASIC), a programmable logic device (e.g., a simple programmable logic device ( Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CPLD), and Field Programmable Gate Array (FPGA)). The processor implements its functions by reading and executing programs stored in the memory 141 or memory 21 .

Note that in FIG. 1, the single memory 141 has been described as storing programs corresponding to each processing function of the processing circuit 144 . Also, in FIG. 4, the single memory 21 has been described as storing the programs corresponding to the respective processing functions of the processing circuit 24 . However, embodiments are not so limited. For example, a plurality of memories 141 may be distributed and the processing circuit 144 may read corresponding programs from the individual memories 141 . Similarly, a plurality of memories 21 may be arranged in a distributed manner, and the processing circuit 24 may be configured to read corresponding programs from individual memories 21 . Also, instead of storing the program in the memory 141 or memory 21, the program may be directly embedded in the circuit of the processor. In this case, the processor realizes its function by reading and executing the program embedded in the circuit.

Each component of each device according to the above-described embodiments is functionally conceptual, and does not necessarily need to be physically configured as illustrated. That is, the specific form of distribution/integration of each device is not limited to the illustrated one, and all or part of them can be functionally or physically distributed/integrated in arbitrary units according to various loads and usage conditions. Can be integrated and configured. Furthermore, all or any part of each processing function performed by each device can be implemented by a CPU and a program analyzed and executed by the CPU, or implemented as hardware based on wired logic.

Moreover, the processing method described in the above embodiments can be realized by executing a processing program prepared in advance on a computer such as a personal computer or a work station. This processing program can be distributed via a network such as the Internet. In addition, this processing program is recorded on a computer-readable non-transitory recording medium such as a hard disk, flexible disk (FD), CD-ROM, MO, DVD, etc., and is executed by being read from the recording medium by a computer. You can also

According to at least one embodiment described above, material discrimination can be performed without additional scanning.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

Reference Signs List 1 medical information processing system 10 X-ray CT system 110 gantry device 140 console device 144 processing circuit 144a scanning function 144b processing function 144c control function 20 medical processing device 24 processing circuit 24a processing function 24b control function

Claims (8)

performing a first scan for acquiring a first data set corresponding to the first X-ray energy by irradiating a first range along the body axis direction of the subject with X-rays, and after the first scan Then, by irradiating X-rays to a second range narrower than the first range along the body axis direction, a second X-ray energy corresponding to a second X energy different from the first X-ray energy is obtained. a scanning unit that performs a second scan that collects a data set;
a processing unit that performs material discrimination using two types of reference materials based on the first data set and the second data set;
An X-ray CT system, comprising: The first data set is collected while moving at least one of the X-ray focal position and the subject along the body axis direction,
2. The X-ray CT system of claim 1, wherein said second data set is acquired while rotating an X-ray focal position around said subject. 3. The X-ray CT system of claim 2, wherein the first data set is acquired without rotating an X-ray focal position around the subject. 4. The X-ray CT system according to claim 3, wherein said second data set is acquired without moving the X-ray focal position and said subject along said body axis direction. The processing unit generates two-dimensional first image data based on the first data set, generates three-dimensional second image data based on the second data set, and generates three-dimensional image data based on the second image data. 5. The X-ray CT system according to claim 3, wherein the two-dimensional third image data is generated by using the first image data and the third image data, and the material discrimination is performed based on the first image data and the third image data. The processing unit identifies a target region in which the disease of the subject is located in the second image data, and performs the material discrimination for a region corresponding to the target region in the first image data and the third image data. 6. The X-ray CT system of claim 5, wherein: The X-ray CT system according to any one of claims 1 to 6, wherein said second range is set based on said first data set. a first data set corresponding to a first X-ray energy collected by irradiating a first range along the body axis of a subject with X-rays; to a second data set corresponding to a second X-energy different from the first X-ray energy, collected after the first data set by irradiating a second range of X-rays narrower than the range of A medical processing apparatus comprising: a processing unit that performs material discrimination using two kinds of reference materials based on the above.

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