JP2021037131A - X-ray ct system and medical processing apparatus - Google Patents

Abstract

To perform substance discrimination without depending on additional scanning.SOLUTION: An X-ray CT system comprises a scanning part and a processing part. The scanning part radiates an X-ray in a first area along a body axial direction of a subject, thereby performing first scanning for collecting a first data set corresponding to a first X-ray energy. After the first scanning, the scanning part radiates an X-ray in a second area, which is narrower than the first area, along the body axial direction, thereby performing second scanning for collecting a second data set corresponding to a second X energy different from the first X-ray energy. The processing part performs substance discrimination by a plurality of reference substances on the basis of the first data set and the second data set.SELECTED DRAWING: Figure 2

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 using two types of X-ray energy, this technique is called Dual Energy (DE), and it is possible to discriminate substances using two types of reference substances.

For example, dual energy technology makes it possible to discriminate substances such as kidney stones, fats, soft tissues, and bones in the body of a subject. Further, for example, according to the dual energy technique, it is possible to determine whether the kidney stone in the body of the subject is a calcium type stone or a uric acid type stone.

Here, the scan is not always performed with dual energy, and the scan with a single energy is often performed. It may also 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 kidney stones and it is determined that dual energy substance discrimination is required to determine if the kidney stones are calcium or uric acid type. There is. Here, if the dual energy scan is executed again, the burden on the subject will be heavy and the exposure amount will also increase.

Japanese Unexamined Patent Publication No. 2018-42604 JP-A-2017-518844 JP-A-2007-268274

A problem to be solved by the present invention is to perform substance discrimination without an additional scan.

The X-ray CT system of the embodiment includes a scanning unit and a processing unit. The scanning unit executes a first scan for collecting 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 the first scan is performed. After one scan, by irradiating a second range narrower than the first range along the body axis direction with X-rays, a second X-ray energy different from the first X-ray energy is obtained. Perform a second scan to collect the corresponding second dataset. The processing unit discriminates substances with 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 of the configuration of the 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 processes of the X-ray CT system according to the first embodiment. FIG. 4 is a block diagram showing an example of the configuration of the medical information processing system according to the second 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, low 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-ray 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 the X-ray high voltage device 114, the wedge 116, the collimator 117, the 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 that is 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 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 around 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 or the like. 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 a CT image for display generated by the processing circuit 144 and the result of substance discrimination. Further, for example, the display 142 displays a GUI (Graphical User Interface) for receiving 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 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 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 executes various scans such as positioning imaging and main scan on the subject P.

Here, the positioning imaging may be executed in two dimensions or may be executed in three dimensions. In this embodiment, a case where two-dimensional positioning imaging is performed will be described as an example. In this case, the scan function 144a does not rotate the X-ray focal position around the subject P, and at least one of the X-ray focal position and the subject P is set in the body axis direction of the subject P (shown in FIG. 1). Positioning imaging is performed while moving along the Z-axis direction).

For example, the scan 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 top plate 133 in the Z-axis direction. .. Further, while the positioning imaging is executed by the scan function 144a, the DAS 118 collects X-ray signals 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.

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 top plate 133 in the Z-axis direction. As a result, projection data is collected for each of the plurality of positions of the subject P in the body axis direction. In the following, a plurality of projection data will be collectively referred to as a projection data set. That is, the scan function 144a collects the projection data set by performing positioning imaging.

Further, the processing circuit 144 generates image data based on the scan result by reading a program corresponding to the processing function 144b from the memory 141 and executing the program. For example, the processing function 144b generates positioning image data based on the projection data set collected by the positioning imaging. The positioning image data may be referred to as a scanno image data or a scout image data.

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

When performing the main scan by the conventional scan method, the scan function 144a rotates the X-ray focal position around the subject P without moving the X-ray focal position and the subject P along the body axis direction. While doing this, perform this scan. 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 top plate 133 stopped.

Further, when the main scan is executed by the helical scan method, the scan function 144a moves the X-ray focal position and the subject P along the body axis direction, and moves the X-ray focal position around the subject P. Perform this scan while rotating with. For example, the scanning function 144a causes the top plate 133 to move in the Z-axis direction and irradiates the subject P with X-rays from the X-ray tube 111 while rotating the X-ray tube 111 around the subject P. ..

When performing the main scan by the step-and-shoot method, the scan function 144a first moves the X-ray focal position and the subject P around the subject P without moving the X-ray focal position along the body axis direction. Perform this 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 top plate 133 stopped. Next, the scanning function 144a moves the top plate 133 in the Z-axis direction in a state where the irradiation of X-rays from the X-ray tube 111 is stopped. Then, the scanning function 144a re-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 top plate 133 stopped.

While this scan is performed by the scan function 144a, the DAS 118 collects X-ray signals from each detection element in the X-ray detector 112 and generates detection data. Further, 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.

That is, the scan function 144a collects projection data for each of a plurality of irradiation directions (views) by irradiating the subject P with X-rays while rotating the focal position of the X-rays around the subject P. That is, the scan function 144a collects the projection data set by executing the main scan.

In addition, the processing function 144b generates CT image data (volume data) based on the projection data set collected by this scan. For example, the processing function 144b generates CT image data by performing reconstruction processing using a filter correction back projection method, a successive approximation reconstruction method, a successive approximation applied reconstruction method, or the like based on a projection data set. .. In addition, the processing function 144b can also generate CT image data by performing reconstruction processing by AI (Artificial Intelligence). For example, the processing function 144b generates CT image data by a DLR (Deep Learning Reconnection) method.

In addition, the processing function 144b discriminates substances with a plurality of reference substances based on the projection data set collected by the positioning imaging and the projection data set collected by the main scan. For example, if the presence of a disease in subject P is revealed based on the projection data set collected by this scan, the processing function 144b will use the projection data set and the projection data set collected by positioning imaging to analyze the disease. Material discrimination is performed based on the projection data set collected by this scan. The substance discrimination 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 converts the positioning image data and the CT image data generated by the processing function 144b into a display image by a known method. As an 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 or the like received from a user via the input interface 143. Then, the control function 144c causes the converted display image to be displayed on the display 142. Further, the control function 144c causes the display 142 to display 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 the positioning image data and the 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 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 included in the processing circuit 144 may be realized by being appropriately distributed or integrated into a single processing circuit 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 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 the scan A11. Specifically, as shown in FIG. 2, the scan function 144a does not rotate the X-ray focal position around the subject P, but moves the X-ray focal position relative to the subject P. However, the subject P is irradiated with X-rays of energy E11. As a result, the scan function 144a irradiates the range R1 along the body axis direction of the subject P with X-rays and collects 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 top plate 133 in the Z-axis direction, and collects the projection data set B11. Further, the processing function 144b generates two-dimensional image data C11 based on the projection data set B11 collected by the scan A11.

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

Next, the control function 144c causes the display 142 to display a reference image based on the image data C11. Further, the control function 144c sets the range R2, which is the scan range of the scan A12, by accepting an input operation from the user who has referred to the reference image. The scan A12 is an example of the second scan. Further, the range R2 is an example of the second range.

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

Next, the scan function 144a executes the scan A12 with respect to the range R2 set in the reference image. Specifically, as shown in FIG. 2, the scanning 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 a result, the scan function 144a irradiates the range R2 along the body axis direction of the subject P with X-rays and collects the projection data set B12 corresponding to the energy E12. For example, the scan function 144a collects the projection data set B12 by performing a conventional scan, a helical scan, a step-and-shoot scan, or the like.

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

In addition, the processing function 144b generates three-dimensional image data C12 based on the projection data set B12 collected by the scan A12. The image data C12 is an example of the second image data. For example, the processing function 144b executes reconstruction processing such as a filter correction back projection method, a successive approximation reconstruction method, a successive approximation applied reconstruction method, and a DLR method based on the projection data set B12, thereby performing a three-dimensional image. Data C12 is reconstructed. That is, the scan A12 is a main scan for collecting CT image data (volume data).

The scan function 144a may be executed in synchronization with the scan A11 and the scan A12 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 A11 and the scan A12 so that the position shift between the scan A11 and the scan A12 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 A11 and the scan A12. For example, the scan function 144a acquires the electrocardiographic waveform of the subject P by an electrocardiograph attached to the subject P. Then, the scan function 144a executes the scan A12 so that the phase of the electrocardiographic waveform in the scan A12 matches the electrocardiographic waveform in the scan A11.

Further, for example, the scan function 144a acquires the respiratory waveform of the subject P in parallel with the scan A11 and the scan A12. 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 between the subject and the abdominal surface 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. You may get it. 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 a rendering process 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-section reconstruction method (MPR: Multi Planar Reconnection). Further, as another example of the rendering process, a two-dimensional image reflecting three-dimensional information is generated from the image data C12 by a volume rendering process or a maximum value projection method (MIP). Processing to be done is mentioned. Then, the control function 144c causes the display 142 to display the display image generated by the rendering process. In addition, the user can diagnose the subject P while referring to the display image.

Here, as a result of performing the diagnosis based on the image data C12, a substance discrimination process may be required. For example, the presence of kidney stones may be clarified as a result of diagnosis, and it may be determined that substance discrimination treatment is necessary to determine whether the kidney stones are calcium type or uric acid type.

However, if the dual energy scan is additionally performed after the scan A12 is completed, the exposure amount of the subject P will increase. Various methods such as kV switching, dual layer, dual source, and split are known as dual energy scanning methods, but any of these methods is generally equivalent to or better than single energy scanning. It becomes the exposure amount of. In addition, if the dual energy scan is performed again and the test is performed again, it will be a burden on the subject P in terms of time and physical strength.

Therefore, the processing function 144b performs substance discrimination without relying on an additional scan. Specifically, the processing function 144b discriminates substances with a plurality of reference substances based on the projection data set B11 and the projection data set B12 already collected by the scan A11 and the scan A12.

More specifically, the processing function 144b first identifies the target region Q1 in which the disease of the subject P is located, based on the image data C12. That is, the processing function 144b segmentes 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 accepting an input operation from a user who has referred to a display image based on the image data C12. Further, 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. Further, 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 generates the image data C13 by synthesizing these MPR images. .. The area of the image data C13 corresponding to the target area Q1 specified in the image data C12 is described as the area Q2.

Further, the processing function 144b specifies the area Q3 corresponding to the target area Q1 specified in the image data C12 in the image data C11. For example, the processing function 144b identifies the area Q3 by aligning the image data C11 and the image data C12 and specifying 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 specifying the area corresponding to the area Q2 of the image data C13 in the image data C11.

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

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

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

Further, 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 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 S107, step S108, step S109, step S110 and step S111 correspond to the processing function 144b. Step S103, step S104, step S105 and step S112 correspond to the control function 144c.

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

Here, the processing circuit 144 determines whether or not the range R2, which is the scan range of the scan A12, has been set by the user who has referred to the reference image (step S105), and waits if the scan range is not set. It becomes a state (step S105 denial). On the other hand, when the scan range is set (step S105 affirmative), the processing circuit 144 executes the scan A12 for the scan range set in the reference image and collects the projection data set B12 corresponding to the energy E12. (Step S106). Next, the processing circuit 144 generates image data C12 based on the projection data set B12 (step S107).

Next, the processing circuit 144 identifies the target region Q1 in which the disease of the subject P is located in the image data C12 (step S108). Next, the processing circuit 144 generates the two-dimensional image data C13 based on the three-dimensional image data C12 (step S109). Further, the processing circuit 144 specifies the 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 may be performed in parallel.

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

As an example of substance discrimination, a process for determining whether a kidney stone of subject P is a calcium type stone or a uric acid type stone has been described so far. However, the embodiment is not limited to this. For example, the processing function 144b can also calculate the mixing amount and mixing ratio of the two reference substances at each position based on the image data C11 and the image data C13 collected with different energies.

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

Here, "μ (E1)" indicates the line attenuation coefficient of each position in the monochromatic X-ray energy "E1", and "μ (E2)" indicates the line attenuation coefficient of each position in the monochromatic X-ray energy "E2". .. Further, "μ _α (E)" indicates the linear attenuation coefficient of the reference substance α, and “μ _β (E)” indicates the linear attenuation coefficient of the reference substance 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 the equation (1), thereby using two kinds of reference substances "α, β". Perform substance discrimination.

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, the processing function 144b generates a substance discrimination image in which the reference substance α is emphasized and a substance discrimination image in which the reference substance β 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 generated for each reference substance, thereby performing a virtual monochromatic X-ray image (monochromematic) at a predetermined energy. It is also possible to generate various images such as (also referred to as an image), a density image, and an effective atomic number image. In addition, the control function 144c causes the display 142 to display an image showing the results of these substance discriminations.

As described above, according to the first embodiment, the scan function 144a collects 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, the scan function 144a executes the scan A12 for collecting the 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 after the scan A11. To do. Further, the processing function 144b performs substance discrimination based on the projection data set B11 corresponding to the energy E11 and the projection data set B12 corresponding to the energy E12. Therefore, the X-ray CT system 10 according to the first embodiment can perform substance discrimination without relying on additional scans other than scan A11 and scan A12.

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

(Second Embodiment)
By the way, 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, although the description has been made so far that the user sets the range R2 which is the scan range of the scan A12, 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 the reference image generated based on the image data C11 and extracting the organ or the like to be diagnosed.

Further, in the above-described embodiment, the case where the 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 be a case where positioning imaging is performed in three dimensions.

For example, the scan function 144a first executes a three-dimensional scan A21 in place of the scan A11 and collects the 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. As a result, the scan function 144a irradiates the range R1 along the body axis direction of the subject P with X-rays and collects the projection data set B21 corresponding to the energy E11. For example, the scan function 144a collects the projection data set B21 by performing a conventional scan, a helical scan, a step-and-shoot scan, or the like. The projection data set B21 is an example of the first data set.

Next, the processing function 144b generates three-dimensional image data C21 based on the projection data set B21 collected by the scan A21. For example, the processing function 144b executes reconstruction processing such as a filter correction back projection method, a successive approximation reconstruction method, a successive approximation applied reconstruction method, and a DLR method based on the projection data set B21 to execute a three-dimensional image. Data C21 is reconstructed.

Next, the control function 144c sets the range R2, which is the scan range of the scan A12, based on the image data C21. Next, the scan function 144a performs scan A12 on the range R2 and collects the projection data set B12 corresponding to the energy E12. Next, the processing function 144b generates three-dimensional image data C12 based on the projection data set B12 collected by the scan A12.

Next, the processing function 144b generates the two-dimensional image data C22 based on the three-dimensional image data C21 and generates the two-dimensional image data C13 based on the three-dimensional image data C12. For example, the processing function 144b generates image data C22 and image data C13 by forward-projecting image data C21 and 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 synthesizes the generated plurality of MPR images to form the image data C22 and the image data C13. To generate.

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

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

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. 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 device 20 that performs substance discrimination.

As shown in FIG. 4, 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. 4, 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 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 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 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 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 an 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. 4, 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. 4 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 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. 4 is realized.

For example, first, the scan function 144a in the X-ray CT system 10 does not rotate the focal position of the X-ray around the subject P, but irradiates the range R1 along the body axis direction of the subject P with the X-ray. Scan A11 is performed in, and the projection data set B11 corresponding to the energy E11 is collected. Alternatively, the scan function 144a executes the scan A21 by irradiating the range R1 along the body axis direction of the subject P with the X-ray while rotating the focal position of the X-ray around the subject P, and performs the scan A21. Collect the projection data set B21 corresponding to E11.

Further, the scan 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. Further, 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 device 20 via the network NW.

Next, the processing function 24a in the medical processing apparatus 20 performs material discrimination with a plurality of reference substances based on the projection data set B11 or the 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. Further, the processing function 24a generates the three-dimensional image data C12 based on the projection data set B12, and generates the two-dimensional image data C13 based on the image data C12. Then, the processing function 24a discriminates substances 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. Further, the processing function 24a generates the three-dimensional image data C12 based on the projection data set B12, and generates the two-dimensional image data C13 based on the image data C12. Then, the processing function 24a discriminates substances 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. Further, the processing function 24a generates three-dimensional image data C12 based on the projection data set B12. Then, the processing function 24a discriminates substances 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 substance discrimination by the processing function 24a. For example, the control function 24b causes the display 22 to display information indicating whether the kidney stone of the subject P is a calcium type stone or a uric acid type stone. Further, for example, the control function 24b causes the display 22 to display an image showing the result of substance discrimination generated by the processing function 24a.

Alternatively, the control function 24b transmits the result of substance discrimination by the processing function 24a to the X-ray CT system 10. In this case, the control function 144c in the X-ray CT system 10 can display the result of substance discrimination transmitted from the medical processing device 20 on the display 142.

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, a simple programmable logic device)). It means a circuit such as a Simple Programmable Logical Device (SPLD), a compound 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.

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. 4, 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. 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, a flexible disk (FD), a CD-ROM, an MO, or a 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, substance discrimination can be performed without additional scanning.

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 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 (8)

A first scan is performed to collect the first data set corresponding to the first X-ray energy by irradiating the first range along the body axis direction of the subject with X-rays, and after the first scan. Then, by irradiating the second range narrower than the first range along the body axis direction with X-rays, the second X-ray energy different from the first X-ray energy corresponds to the second X-ray energy. A scanning unit that executes a second scan that collects data sets,
A processing unit that discriminates substances from a plurality of reference substances based on the first data set and the second data set.
X-ray CT system equipped with. 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.
The X-ray CT system according to claim 1, wherein the second data set is collected while rotating the X-ray focal position around the subject. The X-ray CT system according to claim 2, wherein the first data set is collected without rotating the X-ray focal position around the subject. The X-ray CT system according to claim 3, wherein the second data set is collected without moving the X-ray focal position and the subject along the 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 is based on the second image data. The X-ray CT system according to claim 3 or 4, wherein the two-dimensional third image data is generated, and the substance 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 discriminates the substance with respect to the region corresponding to the target region in the first image data and the third image data. The X-ray CT system according to claim 5. The X-ray CT system according to any one of claims 1 to 6, wherein the second range is set based on the first data set. The first dataset corresponding to the first X-ray energy collected by irradiating the first range along the body axis direction of the subject with X-rays, and the first data set along the body axis direction. By irradiating a second range narrower than the range of, the second dataset corresponding to the second X-energy different from the first X-ray energy collected after the first dataset is obtained. A medical treatment device provided with a treatment unit that discriminates substances based on a plurality of reference substances.

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