JP6824641B2 - X-ray CT device - Google Patents

Description

Embodiments of the present invention relate to an X-ray CT apparatus.

Conventionally, in an X-ray CT apparatus, positioning is performed in order to arrange a subject at an appropriate position for imaging prior to imaging an image for diagnosis. For example, the operator of the X-ray CT device lays down the subject on the top plate of the sleeper device, operates the sleeper device, and inserts the top plate into the gantry. Further, for example, the operator browses the positioning image and moves the subject so that the imaging portion is located near the center of the FOV (Field Of View).

Japanese Unexamined Patent Publication No. 2014-138909 JP-A-2009-261915

An object to be solved by the present invention is to provide an X-ray CT apparatus capable of accurately aligning.

The X-ray CT apparatus according to the embodiment includes a gantry, a top plate, a reconstruction unit, a detection unit, a reception unit, and a movement control unit. The gantry irradiates the subject with X-rays and detects the X-rays that have passed through the subject. The top plate is placed on the subject and inserted into the imaging field of view of the gantry. The reconstructing unit reconstructs the positioning image data from the X-ray data detected by the gantry in the positioning imaging. The detection unit detects each of a plurality of sites in the subject included in the positioning image data. The reception unit receives the setting of the imaging site in the subject. The movement control unit executes movement control for moving at least one of the top plate and the gantry so that the position of the imaging portion included in the positioning image data and the center of the imaging field of view are close to each other.

FIG. 1 is a diagram showing an example of a configuration of a medical information processing system according to the first embodiment. FIG. 2 is a diagram showing an example of the configuration of the X-ray CT apparatus according to the first embodiment. FIG. 3 is a diagram for explaining three-dimensional scanno image capture by the scan control circuit according to the first embodiment. FIG. 4A is a diagram for explaining an example of a portion detection process by the detection function according to the first embodiment. FIG. 4B is a diagram for explaining an example of a portion detection process by the detection function according to the first embodiment. FIG. 5 is a diagram for explaining an example of a portion detection process by the detection function according to the first embodiment. FIG. 6 is a diagram for explaining an example of a portion detection process by the detection function according to the first embodiment. FIG. 7 is a diagram showing an example of a virtual patient image stored by the storage circuit according to the first embodiment. FIG. 8 is a diagram for explaining an example of collation processing by the position collation function according to the first embodiment. FIG. 9 is a diagram showing an example of conversion of the scan range by coordinate conversion according to the first embodiment. FIG. 10 is a flowchart showing a processing procedure by a conventional X-ray CT apparatus. FIG. 11 is a diagram showing an example of alignment-related information stored in the storage circuit according to the first embodiment. FIG. 12 is a diagram for explaining the process by the movement control function according to the first embodiment. FIG. 13 is a diagram for explaining the process by the movement control function according to the first embodiment. FIG. 14 is a flowchart showing a processing procedure by the X-ray CT apparatus according to the first embodiment. FIG. 15 is a block diagram showing a configuration example of a processing circuit of the X-ray CT apparatus according to the second embodiment. FIG. 16 is a diagram for explaining the process by the update function according to the second embodiment. FIG. 17 is a flowchart showing a processing procedure by the X-ray CT apparatus according to the third embodiment. FIG. 18 is a block diagram showing a configuration example of a processing circuit of the X-ray CT apparatus according to the fourth embodiment. FIG. 19 is a diagram for explaining processing by the setting function according to the fourth embodiment. FIG. 20 is a block diagram showing a configuration example of a processing circuit of the X-ray CT apparatus according to the fifth embodiment. FIG. 21 is a diagram for explaining processing in the reception function according to the other embodiment.

Hereinafter, embodiments of an X-ray CT (Computed Tomography) apparatus will be described in detail with reference to the accompanying drawings. Hereinafter, a medical information processing system including an X-ray CT apparatus will be described as an example. In the medical information processing system 100 shown in FIG. 1, only one server device and one terminal device are shown, but in reality, a plurality of server devices and terminal devices can be further included. Further, the medical information processing system 100 can also include, for example, a medical image diagnostic device such as an X-ray diagnostic device, an MRI (Magnetic Resonance Imaging) device, and an ultrasonic diagnostic device.

(First Embodiment)
FIG. 1 is a diagram showing an example of the configuration of the medical information processing system 100 according to the first embodiment. As shown in FIG. 1, the medical information processing system 100 according to the first embodiment includes an X-ray CT device 1, a server device 2, and a terminal device 3. The X-ray CT device 1, the server device 2, and the terminal device 3 can communicate with each other directly or indirectly by, for example, an in-hospital LAN (Local Area Network) installed in the hospital. ing. For example, when a PACS (Picture Archiving and Communication System) is introduced in the medical information processing system 100, each device transmits and receives medical images and the like to and from each other in accordance with the DICOM (Digital Imaging and Communications in Medicine) standard.

Further, in the medical information processing system 100, for example, HIS (Hospital Information System), RIS (Radiology Information System), and the like are introduced to manage various information. For example, the terminal device 3 transmits the inspection order created according to the above system to the X-ray CT device 1 and the server device 2. The X-ray CT device 1 acquires patient information from a patient list (modality work list) for each modality created by an examination order directly received from the terminal device 3 or a server device 2 that has received the examination order, and the patient. Collect X-ray CT image data for each. Then, the X-ray CT apparatus 1 transmits the collected X-ray CT image data and the image data generated by performing various image processing on the X-ray CT image data to the server apparatus 2. The server device 2 stores the X-ray CT image data and the image data received from the X-ray CT device 1, generates the image data from the X-ray CT image data, and responds to the acquisition request from the terminal device 3. The data is transmitted to the terminal device 3. The terminal device 3 displays the image data received from the server device 2 on a monitor or the like. Hereinafter, each device will be described.

The terminal device 3 is a device that is arranged in each medical department in the hospital and operated by a doctor working in each medical department, and is a PC (Personal Computer), a tablet PC, a PDA (Personal Digital Assistant), a mobile phone, or the like. Is. For example, in the terminal device 3, the doctor inputs medical record information such as a patient's symptom and a doctor's findings. Further, the terminal device 3 inputs an inspection order for ordering the inspection by the X-ray CT device 1, and transmits the input inspection order to the X-ray CT device 1 and the server device 2. That is, the doctor in the clinical department operates the terminal device 3 to read the reception information of the patient who visited the hospital and the information of the electronic medical record, examine the corresponding patient, and input the medical record information into the read electronic medical record. Then, the doctor in the clinical department operates the terminal operation 3 to transmit the examination order according to the necessity of the examination by the X-ray CT apparatus 1.

The server device 2 stores medical images (for example, X-ray CT image data and image data collected by the X-ray CT device 1) collected by the medical image diagnostic device, and performs various image processing on the medical image. It is a device for performing, for example, a PACS server. For example, the server device 2 receives a plurality of examination orders from the terminal devices 3 arranged in each clinical department, creates a patient list for each medical image diagnosis device, and creates the created patient list for each medical image diagnosis device. Send to. As an example, the server device 2 receives an examination order for performing an examination by the X-ray CT device 1 from the terminal device 3 of each clinical department, creates a patient list, and X-rays the created patient list. It is transmitted to the CT device 1. Then, the server device 2 stores the X-ray CT image data and the image data collected by the X-ray CT device 1, and stores the X-ray CT image data and the image data in response to the acquisition request from the terminal device 3. Send to 3.

The X-ray CT apparatus 1 collects X-ray CT image data for each patient, and uses the collected X-ray CT image data and image data generated by performing various image processing on the X-ray CT image data as a server. It is transmitted to the device 2. FIG. 2 is a diagram showing an example of the configuration of the X-ray CT apparatus 1 according to the first embodiment. As shown in FIG. 2, the X-ray CT apparatus 1 according to the first embodiment includes a pedestal 10, a sleeper apparatus 20, and a console 30.

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

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

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

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

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

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

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

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

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

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

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

The sleeper device 20 is a device on which the subject P is placed, and has a sleeper drive device 21 and a top plate 22 as shown in FIG. The sleeper drive device 21 moves the top plate 22 in the Z-axis direction (longitudinal direction of the top plate 22) to move the subject P into the rotating frame 15. The top plate 22 is a plate on which the subject P is placed. That is, the top plate 22 is inserted into the FOV (Field Of View) of the gantry 10 on which the subject P is placed.

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

The console 30 is a device that accepts the operation of the X-ray CT device 1 by the operator and reconstructs the X-ray CT image data using the projection data collected by the gantry 10. As shown in FIG. 2, the console 30 includes an input circuit 31, a display 32, a scan control circuit 33, a preprocessing circuit 34, a storage circuit 35, an image reconstruction circuit 36, and a processing circuit 37. ..

The input circuit 31 has a mouse, keyboard, trackball, switch, button, joystick, etc. used by the operator of the X-ray CT device 1 to input various instructions and various settings, and information on the instructions and settings received from the operator. Is transferred to the processing circuit 37. For example, the input circuit 31 receives from the operator the imaging conditions for the X-ray CT image data, the reconstruction conditions for reconstructing the X-ray CT image data, the image processing conditions for the X-ray CT image data, and the like. In addition, the input circuit 31 accepts an operation for selecting a test for a subject. Further, the input circuit 31 accepts a designation operation for designating a portion on the image.

The display 32 is a monitor referred to by the operator, and under the control of the processing circuit 37, the display 32 displays the image data generated from the X-ray CT image data to the operator, or the operator via the input circuit 31. Displays a GUI (Graphical User Interface) for receiving various instructions and various settings from. In addition, the display 32 displays a plan screen for a scan plan, a screen during scanning, and the like. In addition, the display 32 displays a virtual patient image including exposure information, image data, and the like. The virtual patient image displayed by the display 32 will be described in detail later.

The scan control circuit 33 controls the operations of the X-ray irradiation control circuit 11, the gantry drive circuit 16, the data acquisition circuit 14, and the sleeper drive device 21 under the control of the processing circuit 37, thereby displaying the projected data on the gantry 10. Control the collection process. Specifically, the scan control circuit 33 controls the collection process of projection data in the positioning imaging for collecting the positioning image (scano image) and the main imaging (main scan) for collecting the image used for diagnosis. Here, in the X-ray CT apparatus 1 according to the first embodiment, a two-dimensional scanno image and a three-dimensional scanno image can be taken.

For example, the scan control circuit 33 fixes the X-ray tube 12a at a position of 0 degrees (a position in the front direction with respect to the subject), and continuously shoots while moving the top plate 22 at a constant speed. Take a two-dimensional scano image. Alternatively, the scan control circuit 33 fixes the X-ray tube 12a at a position of 0 degrees, moves the top plate 22 intermittently, and intermittently repeats shooting in synchronization with the movement of the top plate, thereby causing two dimensions. Take a scanno image of. Here, the scan control circuit 33 can capture a positioning image from an arbitrary direction (for example, a side surface direction) as well as the front direction with respect to the subject.

In addition, the scan control circuit 33 captures a three-dimensional scanno image by collecting projection data for the entire circumference of the subject when capturing the scanno image. FIG. 3 is a diagram for explaining three-dimensional scanno image capture by the scan control circuit 33 according to the first embodiment. For example, as shown in FIG. 3, the scan control circuit 33 collects projection data for the entire circumference of the subject by helical scan or non-helical scan. Here, the scan control circuit 33 executes a helical scan or a non-helical scan on a wide area such as the entire chest, abdomen, upper body, and whole body of the subject at a lower dose than the main imaging. As the non-helical scan, for example, the above-mentioned step-and-shoot method scan is executed.

In this way, the scan control circuit 33 collects the projection data for the entire circumference of the subject, so that the image reconstruction circuit 36 described later reconstructs the three-dimensional X-ray CT image data (volume data). As shown in FIG. 3, it becomes possible to generate a positioning image from an arbitrary direction using the reconstructed volume data. Here, whether to capture the positioning image in two dimensions or in three dimensions may be arbitrarily set by the operator, or may be preset according to the inspection content.

Returning to FIG. 2, the preprocessing circuit 34 performs logarithmic conversion processing and correction processing such as offset correction, sensitivity correction, and beam hardening correction on the projection data generated by the data acquisition circuit 14. Generate corrected projection data. Specifically, the preprocessing circuit 34 generates corrected projection data for each of the projection data of the positioning image generated by the data acquisition circuit 14 and the projection data collected by the main shooting, and the storage circuit 35. Store in.

The storage circuit 35 stores the projection data generated by the preprocessing circuit 34. Specifically, the storage circuit 35 stores the projection data of the positioning image generated by the preprocessing circuit 34 and the projection data for diagnosis collected by the main imaging. In addition, the storage circuit 35 stores image data and a virtual patient image generated by the image reconstruction circuit 36 described later. Further, the storage circuit 35 appropriately stores the processing result by the processing circuit 37 described later. The virtual patient image and the processing result by the processing circuit 37 will be described later.

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

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

The processing circuit 37 controls the operation of the gantry 10, the sleeper device 20, and the console 30 to control the entire X-ray CT device 1. Specifically, the processing circuit 37 controls the CT scan performed on the gantry 10 by controlling the scan control circuit 33. Further, the processing circuit 37 controls the image reconstruction processing and the image generation processing in the console 30 by controlling the image reconstruction circuit 36. Further, the processing circuit 37 controls the display 32 to display various image data stored in the storage circuit 35.

Further, as shown in FIG. 2, the processing circuit 37 executes the detection function 37a, the position matching function 37b, the reception function 37c, and the movement control function 37d. Here, for example, each processing function executed by the detection function 37a, the position matching function 37b, the reception function 37c, and the movement control function 37d, which are the components of the processing circuit 37 shown in FIG. 2, is a program that can be executed by a computer. It is recorded in the storage circuit 35 in the form. The processing circuit 37 is a processor that realizes a function corresponding to each program by reading each program from the storage circuit 35 and executing the program. In other words, the processing circuit 37 in the state where each program is read has each function shown in the processing circuit 37 of FIG. The processing circuit 37 is an example of a control unit.

The detection function 37a detects a plurality of sites in the subject included in the three-dimensional image data. Specifically, the detection function 37a detects a part such as an organ included in the three-dimensional X-ray CT image data (volume data) reconstructed by the image reconstruction circuit 36. For example, the detection function 37a detects a site such as an organ based on an anatomical landmark for at least one of the volume data of the positioning image and the volume data of the image used for diagnosis. Here, the anatomical feature point is a point showing the feature of a specific part such as a bone, an organ, a blood vessel, a nerve, or a lumen. That is, the detection function 37a detects bones, organs, blood vessels, nerves, lumens, etc. included in the volume data by detecting anatomical feature points such as specific organs and bones. In addition, the detection function 37a can also detect the positions of the head, neck, chest, abdomen, legs, etc. included in the volume data by detecting the characteristic feature points of the human body. The site described in this embodiment means a bone, an organ, a blood vessel, a nerve, a lumen, or the like including these positions. Hereinafter, an example of detecting a portion by the detection function 37a will be described.

For example, the detection function 37a extracts anatomical feature points from the voxel values included in the volume data in the volume data of the positioning image or the volume data of the image used for diagnosis. Then, the detection function 37a compares the three-dimensional position of the anatomical feature point in the information such as a textbook with the position of the feature point extracted from the volume data to obtain the feature point extracted from the volume data. Inaccurate feature points are removed from the inside to optimize the position of the feature points extracted from the volume data. As a result, the detection function 37a detects each part of the subject included in the volume data. As an example, the detection function 37a first extracts anatomical feature points included in the volume data by using a supervised machine learning algorithm. Here, the above-mentioned supervised machine learning algorithm is constructed by using a plurality of supervised images in which correct anatomical feature points are manually arranged, and is used by, for example, a decision forest. Will be done.

Then, the detection function 37a optimizes the extracted feature points by comparing the model showing the three-dimensional positional relationship of the anatomical feature points in the body with the extracted feature points. Here, the above-mentioned model is constructed by using the above-mentioned teacher image, and for example, a point distribution model or the like is used. That is, the detection function 37a is a model in which the shape and positional relationship of the part, points unique to the part, etc. are defined based on a plurality of teacher images in which correct anatomical feature points are manually arranged, and the extracted features. By comparing with points, inaccurate feature points are removed and feature points are optimized. That is, the detection function 37a detects each of a plurality of sites by using the anatomical feature points in the three-dimensional positioning image data. The detection function 37a is an example of a detection unit.

Hereinafter, an example of the site detection process by the detection function 37a will be described with reference to FIGS. 4A, 4B, 5 and 6. 4A, 4B, 5 and 6 are diagrams for explaining an example of a portion detection process by the detection function 37a according to the first embodiment. In FIGS. 4A and 4B, the feature points are arranged two-dimensionally, but in reality, the feature points are arranged three-dimensionally. For example, the detection function 37a applies a supervised machine learning algorithm to the volume data to extract voxels regarded as anatomical feature points as shown in FIG. 4A (black dots in the figure). Then, the detection function 37a fits the position of the extracted voxels to a model in which the shape and positional relationship of the parts, points unique to the parts, etc. are defined, and as shown in FIG. 4B, among the extracted voxels. Inaccurate feature points are removed and only voxels corresponding to more accurate feature points are extracted.

Here, the detection function 37a assigns an identification code for identifying the feature points indicating the features of each part to the extracted feature points (voxels), and the identification code and the position (coordinate) information of each feature point. The information associated with and is attached to the image data and stored in the storage circuit 35. For example, as shown in FIG. 4B, the detection function 37a assigns identification codes such as C1, C2, and C3 to the extracted feature points (voxels). Here, the detection function 37a attaches an identification code to each of the data for which the detection process has been performed, and stores the data in the storage circuit 35. Specifically, the detection function 37a is performed from at least one of the projection data of the positioning image, the projection data collected under non-contrast, and the projection data collected in the state of being imaged by the contrast medium. The site of the subject contained in the reconstructed volume data is detected.

For example, as shown in FIG. 5, the detection function 37a attaches information associated with the coordinates of each voxel detected from the volume data (positioning in the figure) of the positioning image to the volume data to the storage circuit 35. Store in. As an example, the detection function 37a extracts the coordinates of the feature points from the volume data of the positioning image, and as shown in FIG. 5, "identification code: C1, coordinates (x ₁ , y ₁ , z ₁ )". , "identification code: C2, coordinates _{(x 2, y 2, z} 2) " storing in association with such a volume data. Thereby, the detection function 37a can identify what kind of feature point is in which position in the volume data of the positioning image, and can detect each part such as an organ based on this information.

Further, as shown in FIG. 5, for example, the detection function 37a attaches information in which an identification code is associated with the coordinates of each voxel detected from the volume data (scan in the figure) of the image for diagnosis to the volume data. Is stored in the storage circuit 35. Here, the detection function 37a is characterized by the volume data (contrast-enhanced Phase in the figure) imaged by the contrast medium and the volume data (non-contrast-enhanced Phase in the figure) not imaged by the contrast medium in the scan. The coordinates of the points can be extracted and the identification code can be associated with the extracted coordinates.

As an example, the detection function 37a extracts the coordinates of the feature points from the volume data of the non-contrast phase from the volume data of the image for diagnosis, and as shown in FIG. 5, "identification code: C1, coordinates. _{(x '1, y' 1} , z '1) "," identification code: C2, coordinates _{(x' 2, y '2} , z' 2) "storing in association with such a volume data. The detection function 37a, among the volume data of the image for diagnosis, extracts the coordinates of the feature points from the volume data of the contrast Phase, as shown in FIG. 5, "identification code: C1, coordinates (x _{'1 , y '1, z' 1} ) "," identification code: C2, coordinates _{(x '2, y' 2} , z '2) "storing in association with such a volume data. Here, when the feature points are extracted from the volume data of the contrast-enhanced Phase, the feature points that can be extracted by being contrast-enhanced are included. For example, the detection function 37a can extract blood vessels and the like imaged by a contrast agent when extracting feature points from the volume data of the contrast-enhanced Phase. Therefore, when the volume data of the contrast Phase, detection 37a, as shown in FIG. 5, the coordinates of a feature point such as a blood vessel extracted by contrast _{(x '31, y' 31} , z '31) ~ such as the coordinate _{(x '34, y' 34} , z '34), the identification code C31 for identifying each vessel, C32, associates and C33 and C34.

As described above, the detection function 37a can identify what kind of feature point is in which position in the volume data of the positioning image or the diagnostic image, and the organ or the like is based on this information. Each part of the can be detected. For example, the detection function 37a detects the position of the target site by using the information of the anatomical positional relationship between the target site to be detected and the site around the target site. As an example, when the target site is the "lung", the detection function 37a acquires the coordinate information associated with the identification code indicating the characteristics of the lung, and also obtains the "ribs", "clavicle", and "heart". , The coordinate information associated with the identification code indicating the surrounding part of the "lung" such as the "diaphragm" is acquired. Then, the detection function 37a extracts the region of the "lung" in the volume data by using the information of the anatomical positional relationship between the "lung" and the surrounding portion and the acquired coordinate information.

For example, the detection function 37a is based on the positional relationship information such as "lung apex: 2-3 cm above the clavicle" and "lower end of the lung: height of the 7th rib" and the coordinate information of each part. As shown in, the region R1 corresponding to the “lung” in the volume data is extracted. That is, the detection function 37a extracts the coordinate information of the voxels in the region R1 in the volume data. The detection function 37a associates the extracted coordinate information with the part information, attaches it to the volume data, and stores it in the storage circuit 35. Similarly, as shown in FIG. 6, the detection function 37a can extract the region R2 and the like corresponding to the “heart” in the volume data.

Further, the detection function 37a detects a position included in the volume data based on a feature point that defines a position of the head, chest, or the like in the human body. Here, the positions of the head, chest, etc. in the human body can be arbitrarily defined. For example, if the area from the 7th cervical spine to the lower end of the lung is defined as the chest, the detection function 37a detects from the feature point corresponding to the 7th cervical spine to the feature point corresponding to the lower end of the lung as the chest. The detection function 37a can detect the site by various methods other than the method using the above-mentioned anatomical feature points. For example, the detection function 37a can detect a portion included in the volume data by a region expansion method based on a voxel value or the like.

The position collation function 37b collates the positions of the plurality of parts in the subject included in the three-dimensional image data with the positions of the plurality of parts in the human body included in the virtual patient data. Here, the virtual patient data is information representing a standard position of each of a plurality of parts in the human body. That is, the position collation function 37b collates the part of the subject with the position of the standard part, and stores the collation result in the storage circuit 35. For example, the position matching function 37b matches a virtual patient image in which a part of the human body is arranged at a standard position with a volume data of a subject.

Here, first, a virtual patient image will be described. The virtual patient image is an image actually taken by X-ray of a human body having a standard physique according to multiple combinations of parameters related to physique such as age, adult / child, male / female, weight, and height. It is generated in advance and stored in the storage circuit 35. That is, the storage circuit 35 stores data of a plurality of virtual patient images according to the combination of the above-mentioned parameters. Here, anatomical feature points (feature points) are associated with and stored in the virtual patient image stored by the storage circuit 35. For example, the human body has a large number of anatomical features that can be relatively easily extracted from an image based on its morphological features and the like by image processing such as pattern recognition. The positions and arrangements of these many anatomical features in the body are roughly determined according to the physique such as age, adult / child, male / female, weight, and height.

In the virtual patient image stored by the storage circuit 35, a large number of these anatomical feature points are detected in advance, and the position data of the detected feature points is attached to the data of the virtual patient image together with the identification code of each feature point. Or it is associated and stored. FIG. 7 is a diagram showing an example of a virtual patient image stored by the storage circuit 35 according to the first embodiment. For example, as shown in FIG. 7, the memory circuit 35 has identification codes “V1”, “V2” and identification codes “V1”, “V2” for identifying anatomical feature points and feature points on a three-dimensional human body including a part such as an organ. A virtual patient image associated with "V3" or the like is stored.

That is, the storage circuit 35 stores the coordinates of the feature points in the coordinate space of the three-dimensional human body image in association with the corresponding identification code. As an example, the storage circuit 35 stores the coordinates of the corresponding feature points in association with the identification code “V1” shown in FIG. Similarly, the storage circuit 35 stores the identification code and the coordinates of the feature point in association with each other. In FIG. 7, only the lungs, heart, liver, stomach, kidneys, etc. are shown as organs, but in reality, the virtual patient image includes a larger number of organs, bones, vasculars, nerves, and the like. .. Further, in FIG. 7, only the feature points corresponding to the identification codes “V1”, “V2” and “V3” are shown, but in reality, a larger number of feature points are included.

The position matching function 37b matches the feature points in the volume data of the subject detected by the detection function 37a with the feature points in the virtual patient image described above by using the identification code, and matches the coordinate space of the volume data. Associate with the coordinate space of the virtual patient image. FIG. 8 is a diagram for explaining an example of collation processing by the position collation function 37b according to the first embodiment. Here, in FIG. 8, matching is performed using three sets of feature points to which identification codes indicating the same feature points are assigned between the feature points detected from the scanno image and the feature points detected from the virtual patient image. However, the embodiment is not limited to this, and matching can be performed using any set of feature points.

For example, as shown in FIG. 8, the position matching function 37b has the feature points indicated by the identification codes “V1”, “V2” and “V3” in the virtual patient image and the identification codes “C1” and “C2” in the scanno image. When matching with the feature points indicated by "" and "C3", the coordinate space between the images is associated by performing coordinate transformation so that the positional deviation between the same feature points is minimized. For example, as shown in FIG. 8, the position matching function 37b has the same anatomically the same feature points “V1 (x1, y1, z1), C1 (X1, Y1, Z1)” and “V2 (x2, y2, z2). ), C2 (X2, Y2, Z2) ”,“ V3 (x3, y3, z3), C3 (X3, Y3, Z3) ”so as to minimize the total“ LS ”of the positional deviation below. Find the coordinate conversion matrix "H".

LS = ((X1, Y1, Z1) -H (x1, y1, z1))
+ ((X2, Y2, Z2) -H (x2, y2, z2))
+ ((X3, Y3, Z3) -H (x3, y3, z3))

The position collation function 37b can convert the scan range designated on the virtual patient image into the scan range on the positioning image by the obtained coordinate transformation matrix “H”. For example, the position collation function 37b uses the coordinate transformation matrix “H” to change the scan range “SRV” specified on the virtual patient image to the scan range “SRC” on the positioning image, as shown in FIG. Can be converted. FIG. 9 is a diagram showing an example of conversion of the scan range by coordinate conversion according to the first embodiment. For example, as shown on the virtual patient image of FIG. 9, when the operator sets the scan range “SRV” on the virtual patient image, the position collation function 37b uses the coordinate transformation matrix described above to perform the set scan. Convert the range "SRV" to the scan range "SRC" on the scanno image.

As a result, for example, the scan range "SRV" set to include the feature points corresponding to the identification code "Vn" on the virtual patient image has the identification code "Cn" corresponding to the same feature points on the scanno image. Is converted to and set to the scan range "SRC" including. The coordinate transformation matrix "H" described above may be stored in the storage circuit 35 for each subject and appropriately read out and used, or calculated each time a scanno image is collected. It may be the case. As described above, according to the first embodiment, the virtual patient image is displayed for specifying the range at the time of presetting, and the position / range is planned on the virtual patient image, so that after the positioning image (scano image) is taken. , The position / range on the positioning image corresponding to the planned position / range can be automatically set numerically.

Returning to the description of FIG. 2, the processing circuit 37 executes the reception function 37c and the movement control function 37d, and controls for accurate alignment. The control will be described in detail later.

In FIG. 2, it is assumed that the single processing circuit 37 realizes the processing functions performed by the detection function 37a, the position matching function 37b, the reception function 37c, and the movement control function 37d. Independent processors may be combined to form a processing circuit, and each processor may execute a program to realize a function.

The term "processor" used in the above description refers to, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an integrated circuit for a specific application (Application Specific Integrated Circuit: ASIC), or a programmable logic device (for example,). It means circuits such as Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CPLD), and Field Programmable Gate Array (FPGA). Processor is a storage circuit. The function is realized by reading and executing the program stored in the storage circuit 35. Instead of storing the program in the storage circuit 35, the program may be directly incorporated in the circuit of the processor. In this case, it may be configured. The processor realizes a function by reading and executing a program embedded in the circuit. Note that each processor of the present embodiment is not limited to the case where each processor is configured as a single circuit, and a plurality of independent processors are used. The circuits may be combined to form one processor to realize the function. Further, the plurality of components in FIG. 2 may be integrated into one processor to realize the function.

By the way, conventionally, the alignment of the subject P is performed prior to the diagnostic imaging (hereinafter, also appropriately referred to as “main scan”). Here, the alignment means, for example, adjusting the position of the subject P placed on the top plate 22 to an appropriate position for photographing.

FIG. 10 is a flowchart showing a processing procedure by a conventional X-ray CT apparatus. The X-ray CT apparatus is in a standby state until the inspection is started (step S11 affirmative). As shown in FIG. 10, when the inspection is started (affirmation in step S11), the operator performs alignment (step S12). For example, an operator (radiologist or the like) lays the subject P on the top plate 22 and operates the sleeper device 20 to insert the top plate 22 into the gantry 10. Subsequently, the operator executes taking a positioning image (step S13). Then, the X-ray CT apparatus 1 reconstructs and displays the positioning image (step S14). For example, the X-ray CT apparatus 1 generates and displays image data of a positioning image using transmission data obtained by irradiating X-rays from one direction (for example, 0 degree direction).

When the positioning image is displayed, the operator determines whether or not the position of the subject P is appropriate (step S15). For example, the operator browses the displayed positioning image, and whether or not the position of the subject P is appropriate based on whether or not the imaging site is located near the center of the FOV (Field Of View). To judge. Here, when it is determined that the position of the subject P is appropriate (step S15 affirmative), diagnostic imaging is executed (step S16). The FOV is an example of a shooting field of view.

On the other hand, if it is determined that the position of the subject P is not appropriate (denial in step S15), the process returns to step S12, and the operator repositions the subject P. For example, the operator adjusts the vertical position of the imaging portion by operating the sleeper device 20 to move the top plate 22 in the vertical direction. Further, for example, the operator adjusts the position of the imaging portion in the left-right direction by having the subject P on the top plate 22 move in the left-right direction.

Then, the positioning image is taken (step S13), and then the positioning image is reconstructed and displayed (step S14). As described above, the processes of steps S12 to S14 are repeatedly executed until the position of the subject P is determined to be appropriate.

The above processing procedure illustrated in FIG. 10 is only an example. For example, the acquisition of the positioning image does not have to be performed over and over again. For example, even if the operator performs the second alignment, the operator may take a diagnostic image without taking the second positioning image. Further, if the top plate 22 can be moved in the left-right direction, the operator may adjust the position of the imaging portion in the left-right direction by moving the top plate 22 in the left-right direction.

Here, in the conventional X-ray CT apparatus, the alignment of the subject P depends on the experience of the operator. For example, even if an experienced operator can accurately position the subject P at the center of the FOV, it is difficult for an inexperienced operator to accurately position the subject P. Moreover, even an experienced operator may have variations among the operators.

If the subject P is not properly aligned, the image data captured by this scan may be affected. For example, the closer to the center of the FOV, the stronger the dose of X-rays irradiated, so the greater the deviation from the center of the FOV, the more likely it is that artifacts due to overflow will occur. Further, for example, if the alignment at the time of capturing the positioning image is not accurate, an error occurs in the dose of X-rays set based on the positioning image, and as a result, the image quality is affected.

Therefore, the X-ray CT apparatus 1 according to the first embodiment includes the configuration described below in order to perform accurate alignment.

The storage circuit 35 stores, for example, alignment-related information related to alignment. For example, the storage circuit 35 stores alignment-related information for each shooting plan.

FIG. 11 is a diagram showing an example of alignment-related information stored in the storage circuit 35 according to the first embodiment. As shown in FIG. 11, the alignment-related information stored in the storage circuit 35 is information in which the imaging plan, the imaging portion, the scanning start position, and the scanning end position are associated with each other. Of these, the imaging plan is a list of imaging plans registered in the X-ray CT apparatus 1. The imaging site is information representing the site of the subject to be imaged in the imaging plan, such as the lungs, large intestine, and head. Further, the representative point is a point representing the position of the imaging portion set based on the feature point. The predetermined position is information indicating an appropriate position of the imaging portion. For example, the predetermined position is a position set based on the center of the FOV, and when the representative point of the imaging portion coincides with the predetermined position, the imaging portion is set to be located at the center of the FOV. .. The alignment-related information stored in the storage circuit 35 is registered in advance by, for example, an operator.

As shown in FIG. 11, for example, the alignment-related information stored in the storage circuit 35 includes the imaging plan “AAA”, the imaging site “brain”, the representative point “center of gravity of the skull”, and the predetermined position “FOV”. Includes information associated with "center". This information indicates that the brain is located at the center of the FOV when the imaging site of the imaging plan named "AAA" is the "brain" and the "center of gravity of the skull" and the "center of the FOV" coincide. The alignment-related information stored in the storage circuit 35 includes the imaging plan "BBB", the imaging site "orbit", the representative point "midpoint of the outer corners of both eyes", and the predetermined position "FOV center". Includes information associated with "3 cm above". This information is obtained when the imaging site of the imaging plan named "BBB" is the "orbit" and the "midpoint of the outer corners of both eyes" and "3 cm above the center of the FOV" coincide. Indicates that it is located in the center of the FOV. The alignment-related information stored in the memory circuit 35 includes the imaging plan "CCC", the imaging site "left lung field", the representative point "center of gravity of the left lung field", and the predetermined position "FOV center". Includes information associated with. This information is obtained when the imaging site of the imaging plan named "CCC" is the "left lung field" and the "center of gravity of the left lung field" and the "FOV center" match, the left lung field is Indicates that it is located at the center of the FOV. Further, the alignment-related information stored in the storage circuit 35 can be similarly included in other shooting plans.

Note that FIG. 11 is only an example. For example, in the example of FIG. 11, the case where the alignment-related information is associated with each shooting plan is illustrated, but the embodiment is not limited to this. For example, instead of the imaging plan, information on the examination order from the doctor (examination purpose, etc.) may be stored. In this case, alignment-related information is associated with each inspection order information.

The reception function 37c receives the setting of the imaging site in the subject P. For example, the reception function 37c receives an input from the operator to specify the shooting plan. Then, the reception function 37c refers to the alignment-related information stored in the storage circuit 35, and receives the information of the imaging portion corresponding to the imaging plan specified by the received input. The reception function 37c is an example of the reception unit.

For example, when the imaging plan "AAA" is specified by the operator, the reception function 37c refers to the alignment-related information stored in the storage circuit 35, and refers to the imaging region "brain" corresponding to the imaging plan "AAA". Accept information.

Further, the reception function 37c receives an execution instruction from the operator to execute the movement control of the top plate 22. For example, the reception function 37c displays on the display 32 a button indicating that the movement control of the top plate 22 is executed and a button indicating that the movement control of the top plate 22 is not executed. Then, the reception function 37c receives an instruction as to whether or not to execute the movement control of the top plate 22 according to which button is designated by the operator.

The movement control function 37d executes movement control for moving the top plate 22 so that the position of the imaging portion included in the positioning image data and the center of the imaging field of view are close to each other. For example, the movement control function 37d executes movement control so that a representative point representing the position of the imaging portion set based on the feature point and a predetermined position set based on the center of the imaging field of view match. To do. Specifically, the movement control function 37d executes movement control so that a representative point set based on a feature point of a portion whose pixel value in the positioning image data is different from that of the peripheral portion coincides with a predetermined position. To do. The movement control function 37d is an example of a movement control unit.

12 and 13 are diagrams for explaining the processing by the movement control function according to the first embodiment. FIG. 12 illustrates the moving direction of the top plate 22 when viewed from the longitudinal direction of the top plate 22. Further, FIG. 13 illustrates an example of processing of the movement control function when the brain is designated as the imaging site.

As shown in FIG. 12, the movement control function 37d controls to move the top plate 22 on which the subject P is placed in the vertical direction, the horizontal direction, and the rotation direction. Specifically, the movement control function 37d has a maximum movement amount set in each of the vertical direction, the horizontal direction, and the rotation direction, and moves the top plate 22 within the range of the maximum movement amount. Here, the maximum amount of movement in each direction is set so that the subject P or the top plate 22 does not come into contact with the inner wall of the opening of the gantry 10 into which the subject P is inserted, for example.

As shown in FIG. 13, the movement control function 37d controls the movement of the top plate 22 based on the position of the imaged portion in the positioning image. Here, a case where the positioning image shown in the left figure of FIG. 13 is obtained when the brain is the imaging site will be described. In this case, the movement control function 37d refers to the alignment-related information illustrated in FIG. 11, and includes information on the representative point “center of gravity of the skull” corresponding to the imaging site “brain” and information on the predetermined position “FOV center”. To get.

Subsequently, the movement control function 37d calculates the position of the center of gravity of the skull in the three-dimensional positioning image data of the subject P. Specifically, the movement control function 37d identifies the position of the skull from a plurality of positions detected by the detection function 37a. Then, the movement control function 37d calculates the position of the center of gravity of the skull by calculating the center of gravity of the three-dimensional coordinates of each pixel (voxel) specified as the position of the skull.

Then, the movement control function 37d moves the top plate 22 so that the calculated position of the center of gravity of the skull coincides with the position of the center of the FOV. In the example of the left figure of FIG. 13, the center of gravity of the skull is located at the lower right in the figure at the center of the FOV. In this case, the movement control function 37d moves the top plate 22 to the upper left in the drawing to match the position of the center of gravity of the skull with the position of the center of the FOV as shown in the right figure of FIG.

In this way, the movement control function 37d executes movement control for moving the top plate 22 so that the position of the imaging portion included in the three-dimensional positioning image data and the center of the FOV are close to each other.

Note that FIGS. 12 and 13 are merely examples. For example, the predetermined site is not necessarily limited to the "FOV center". For example, the movement control function 37d moves so that the representative point "midpoint of the position of the outer corner of the eye" and the predetermined part "3 cm above the center of the FOV" coincide with each other when the imaging site is the "orbit". Control is executed (see FIG. 11). Further, for example, the movement control function 37d may adjust the orientation of the subject P by rotating the top plate 22 in the rotation direction of FIG. In this case, the movement control function 37d may rotate the top plate 22 within a range in which the subject P does not fall.

FIG. 14 is a flowchart showing a processing procedure by the X-ray CT apparatus 1 according to the first embodiment. The processing procedure shown in FIG. 14 is started when an instruction to start the inspection is input by the operator.

In step S101, the processing circuit 37 determines whether or not the inspection has been started. For example, when the operator inputs an instruction to start the inspection, the processing circuit 37 starts the inspection and executes the processing in step S102 and subsequent steps. If step S101 is denied, the processing circuit 37 does not start the inspection and is in a standby state.

If step S101 is affirmed, alignment is performed in step S102. For example, the operator lays the subject P on the top plate 22 and operates the sleeper device 20 to insert the top plate 22 into the gantry 10.

In step S103, the scan control circuit 33 executes taking a positioning image. For example, the scan control circuit 33 captures a positioning image in three dimensions by collecting projection data for the entire circumference of the subject by helical scan or non-helical scan.

In step S104, the image reconstruction circuit 36 reconstructs the volume data of the positioning image. For example, the image reconstruction circuit 36 reconstructs the volume data of the positioning image from the projection data collected by taking the positioning image.

In step S105, the detection function 37a detects a site from the volume data. For example, the detection function 37a detects a part such as an organ included in the volume data of the positioning image based on the anatomical feature point.

In step S106, the processing circuit 37 displays the positioning image. For example, the processing circuit 37 generates and displays image data of a predetermined cross section (for example, 0 degree direction, 90 degree direction, etc.) from the volume data of the positioning image reconstructed by the image reconstruction circuit 36. The direction of the predetermined cross section displayed here is preset in any direction of the operator.

In step S107, the processing circuit 37 determines whether or not to execute the movement control of the top plate 22. For example, the reception function 37c receives an instruction as to whether or not to execute the movement control of the top plate 22. Then, when the reception function 37c receives an instruction to execute the movement control of the top plate 22, the processing circuit 37 determines that the movement control of the top plate 22 is executed, and proceeds to the process of step S108. On the other hand, when the reception function 37c receives an instruction not to execute the movement control of the top plate 22, the processing circuit 37 determines that the movement control of the top plate 22 is not executed, and proceeds to the process of step S110.

If step S107 is affirmed, in step S108, the reception function 37c accepts the imaging portion. For example, the reception function 37c refers to the alignment-related information stored in the storage circuit 35, and receives information on the imaging portion corresponding to the imaging plan input by the operator.

In step S109, the movement control function 37d executes the movement control of the top plate 22 so that the imaging portion approaches the center of the FOV. For example, the movement control function 37d refers to the alignment-related information stored in the storage circuit 35, and the subject P is placed on the subject P based on the information of the representative point corresponding to the imaging site and the information of the predetermined position. The top plate 22 is moved.

In step S110, the scan control circuit 33 executes diagnostic imaging. For example, the scan control circuit 33 collects projection data for the entire circumference of the subject P. After that, the image reconstruction circuit 36 reconstructs the three-dimensional X-ray CT image data (volume data) based on the collected projection data.

Note that FIG. 14 is only an example. For example, the above processing procedures do not necessarily have to be performed in the order described above. For example, the processes of steps S101 to S110 may be executed in an appropriate order within a range in which the processing contents do not contradict each other. For example, the process of step S105 for detecting the site from the volume data may be executed in any order as long as it is completed before step S109 is executed.

As described above, in the X-ray CT apparatus 1 according to the first embodiment, the image reconstruction circuit 36 reconstructs the positioning image data from the X-ray data detected by the gantry 10 in the positioning imaging. The detection function 37a detects each of a plurality of sites in the subject P included in the positioning image data. The reception function 37c receives the setting of the imaging site in the subject P. The movement control function 37d executes movement control for moving the top plate 22 so that the position of the imaging portion included in the positioning image data and the center of the imaging field of view are close to each other. According to this, the X-ray CT apparatus 1 according to the first embodiment can accurately perform alignment.

For example, since the X-ray CT apparatus 1 collects the projection data of the positioning image three-dimensionally, more information on the positioning of the subject P can be collected at the same dose as the conventional positioning image collection from one direction. can do. As a result, the X-ray CT apparatus 1 can quickly display a positioning image of the subject P in an arbitrary direction, and can accurately grasp the position of the subject P in the FOV. Then, by using the information on the position of the subject P, the X-ray CT apparatus 1 can accurately perform the alignment. For example, the X-ray CT apparatus 1 can accurately perform alignment even by an inexperienced operator.

Further, for example, the X-ray CT apparatus 1 can improve the image quality of image data for diagnosis by accurate positioning. For example, the X-ray CT apparatus 1 automatically adjusts the imaging region according to the inspection purpose to the center of the FOV, so that there is no variation among operators, and the image quality can be stabilized. Further, for example, the X-ray CT apparatus 1 has a small deviation from the center of the FOV, so that artifacts caused by overflow can be reduced. Further, for example, the X-ray CT apparatus 1 can accurately calculate the dose of X-rays emitted in this scan by using the projection data of the positioning image three-dimensionally, so that the image quality can be improved. Can be done.

Further, for example, the X-ray CT apparatus 1 accurately adjusts the position and accurately calculates the X-ray dose by taking a positioning image once. Therefore, since the X-ray CT apparatus 1 does not take the positioning image more than once, it is possible to reduce the exposure dose of the subject P and shorten the examination time.

Further, for example, the X-ray CT apparatus 1 executes movement control using representative points based on feature points of a portion whose pixel value (CT value) in the positioning image data is three-dimensionally different from that of the peripheral portion. Specifically, as illustrated in FIG. 11, the X-ray CT apparatus 1 executes movement control using representative points based on feature points such as bones, lung fields, and body surface. According to this, the X-ray CT apparatus 1 can accurately identify the representative point in the positioning image data even if the positioning image data is collected at a low dose, for example. Therefore, the X-ray CT apparatus 1 can accurately perform alignment.

In the above embodiment, the case where volume data, which is three-dimensional medical image data, is used as the positioning image data has been described, but the embodiment is not limited to this. For example, each process described in the above embodiment can be similarly applied when the positioning image data is two-dimensional medical image data. However, it is preferable to use three-dimensional positioning image data in order to accurately perform alignment in the three-dimensional space.

(Modification example of the first embodiment: correction of the amount of movement according to the body shape)
The X-ray CT apparatus 1 according to the first embodiment may correct the movement amount according to the body shape of the subject P.

The movement control function 37d estimates the body shape of the subject P based on the position of the body surface of the subject P, and corrects the movement amount in the movement control according to the estimated body shape.

Here, a case where the imaging site is the “left lung field” will be described (see FIG. 11). In this case, for example, the movement control function 37d specifies the position of the body surface of the abdomen of the subject P from the three-dimensional positioning image data of the subject P. Then, the movement control function 37d calculates the length of the waist circumference of the subject P as an index of the body shape by using the position of the body surface of the specified abdomen. Then, when the calculated waist circumference length differs to some extent from the standard value, the movement control function 37d offsets the predetermined position in FIG. 11 by a predetermined amount in a predetermined direction. For example, the movement control function 37d offsets the predetermined position "FOV center" by several centimeters upward when the waist circumference is longer than the standard value. As an example, the movement control function 37d corrects a predetermined position corresponding to the imaging site “left lung field” to “2 cm above the center of the FOV”.

In this way, the movement control function 37d corrects the movement amount according to the body shape of the subject P. Therefore, the movement control function 37d can be accurately aligned according to the body shape of the subject P.

(Second Embodiment)
In the first embodiment, the case where the alignment-related information stored in the storage circuit 35 is registered in advance by the operator has been described, but the embodiment is not limited to this. For example, the X-ray CT apparatus 1 may learn the appropriate position of the imaging portion in the FOV and update the alignment-related information.

FIG. 15 is a block diagram showing a configuration example of the processing circuit 37 of the X-ray CT apparatus 1 according to the second embodiment. The X-ray CT apparatus 1 according to the second embodiment has the same configuration as the X-ray CT apparatus 1 illustrated in FIG. 2, and is different in that it includes the processing circuit 37 shown in FIG. Therefore, in the second embodiment, the points different from those in the first embodiment will be mainly described, and the points having the same functions as those described in the first embodiment are the same as those in FIG. The reference numerals are given and the description thereof will be omitted.

As shown in FIG. 15, the processing circuit 37 according to the second embodiment has the same configuration as the processing circuit 37 illustrated in FIG. 2, and further includes an update function 37e. The update function 37e records the change in the position of the representative point by the operator, and updates the predetermined position based on the recorded changed position. The update function 37e is an example of an update unit.

For example, the update function 37e receives an operation to change the position of the representative point from the operator. Specifically, the update function 37e receives from the operator an operation of changing the position of the imaging portion with respect to the FOV on the positioning image displayed on the display 32. As an example, after the movement control function 37d executes the movement control so that the center of gravity of the skull and the center of the FOV coincide with each other, the operator may further move the imaging site "1 cm downward". In such a case, the update function 37e records the operation performed by the operator to move "down 1 cm".

Then, the update function 37e updates the alignment-related information stored in the storage circuit 35 based on the recorded operation content of moving the information "down 1 cm". For example, among the alignment-related information shown in FIG. 11, the predetermined position “FOV center” corresponding to the representative point “center of gravity of the skull” is updated to “1 cm below the FOV center”. As a result, the update function 37e updates the alignment-related information shown in FIG. 11 with the alignment-related information shown in FIG. Note that FIG. 16 is a diagram for explaining the process by the update function 37e according to the second embodiment.

As described above, in the X-ray CT apparatus 1 according to the second embodiment, the update function 37e records the change in the position of the representative point by the operator, and the predetermined position is based on the recorded changed position. To update. Then, the movement control function 37d executes the movement control so that the representative point and the predetermined position updated by the update function 37e match. As a result, the X-ray CT apparatus 1 can improve the accuracy of alignment of the imaging portion.

(Third Embodiment)
In the above embodiment, the case where one imaging site is imaged in one examination is illustrated, but the embodiment is not limited to this. For example, the X-ray CT apparatus 1 can be applied to a case where a plurality of imaging parts are imaged in one examination.

The X-ray CT apparatus 1 according to the third embodiment has the same configuration as the X-ray CT apparatus 1 illustrated in FIG. 2, and a part of the processing in the reception function 37c and the movement control function 37d is different. Therefore, in the third embodiment, the differences from the first embodiment will be mainly described.

The reception function 37c according to the third embodiment accepts a plurality of imaging parts. Further, in the movement control function 37d according to the third embodiment, in each of the imaging of the plurality of imaging regions received by the reception function 37c, the position of each imaging region and the center of each imaging field of view are brought closer to each other. Execute movement control.

FIG. 17 is a flowchart showing a processing procedure by the X-ray CT apparatus 1 according to the third embodiment. The processing procedure shown in FIG. 17 is started when an instruction to start the inspection is input by the operator. In the processing procedure shown in FIG. 17, each process of steps S201 to S207 is the same as each process of steps S101 to S107 shown in FIG. 14, so description thereof will be omitted. Further, in the processing procedure shown in FIG. 17, the processing in step S210 is the same as the processing in step S110 shown in FIG. 14, so the description thereof will be omitted.

When step S207 is affirmed, in step S208, the reception function 37c accepts a plurality of imaging parts. For example, the reception function 37c accepts the designation of the photographing plans “AAA” and “CCC” from the operator for one inspection. Then, the reception function 37c refers to the alignment-related information illustrated in FIG. 11, the information of the imaging site “brain” corresponding to the imaging plan “AAA”, and the imaging region “left” corresponding to the imaging plan “CCC”. Accepts information on "lung field".

In step S209, the movement control function 37d executes the movement control of the top plate 22 so that each imaging portion approaches the center of the FOV in the imaging of each imaging region. For example, the movement control function 37d refers to the alignment-related information illustrated in FIG. 11 and obtains information on the representative point “center of gravity of the skull” corresponding to the imaging site “brain” and information on the predetermined position “FOV center”. get. Further, the movement control function 37d acquires the information of the representative point “center of gravity of the left lung field” corresponding to the imaging site “left lung field” and the information of the predetermined position “FOV center”. Then, the movement control function 37d executes the movement control of the top plate 22 so that each imaging site approaches the FOV center in each of the imaging of the brain and the imaging of the left lung field.

For example, when the brain is photographed in the first image and the left lung field is imaged in the second image, the movement control function 37d first matches the position of the center of gravity of the skull with the position of the center of FOV. As described above, the top plate 22 is moved to perform imaging of the brain. Then, when the imaging of the brain is completed, the movement control function 37d moves the top plate 22 so that the position of the center of gravity of the left lung field matches the position of the center of the FOV, and executes the imaging of the left lung field. Let me. Here, when the height of the top plate 22 in the first shooting and the height of the top plate 22 in the second shooting are different, the movement control function 37d is a process of changing the position of the top plate 22 in the longitudinal direction. The height of the top plate 22 may be changed with. That is, in this case, the movement control function 37d linearly (obliquely) extends from the position of the top plate 22 when the first shooting is completed to the position of the top plate 22 when the second shooting is started. ) You may move it.

As described above, the X-ray CT apparatus 1 according to the third embodiment can be applied to the case where a plurality of imaging parts are imaged in one examination. When photographing a plurality of imaging parts, the imaging order of each imaging portion can be arbitrarily set, but it is preferable to photograph in the order along the longitudinal direction of the top plate 22. For example, it is preferable that the X-ray CT apparatus 1 captures images in the order of head to lower limbs or from lower limbs to head.

(Fourth Embodiment)
In the above embodiment, the case where the X-ray CT apparatus 1 adjusts the subject P has been described, but an appropriate FOV range may be further set.

FIG. 18 is a block diagram showing a configuration example of the processing circuit 37 of the X-ray CT apparatus 1 according to the fourth embodiment. The X-ray CT apparatus 1 according to the fourth embodiment has the same configuration as the X-ray CT apparatus 1 illustrated in FIG. 2, except that the processing circuit 37 shown in FIG. 18 is provided. Therefore, in the fourth embodiment, the points different from those in the first embodiment will be mainly described, and the points having the same functions as the configuration described in the first embodiment are the same as those in FIG. The reference numerals are given and the description thereof will be omitted.

As shown in FIG. 18, the processing circuit 37 according to the fourth embodiment has the same configuration as the processing circuit 37 illustrated in FIG. 2, and further includes a setting function 37f. The setting function 37f sets the range of the FOV based on the position of the imaging portion after the movement control is executed. The setting function 37f is an example of a setting unit.

FIG. 19 is a diagram for explaining the process by the setting function 37f according to the fourth embodiment. FIG. 19 illustrates the range of FOV before and after the movement control of the top plate 22. The range of FOV is defined by, for example, the irradiation range of X-rays. Specifically, the irradiation range in the X-ray slice direction is adjusted by the thickness and position of the wedge (bowtie filter) 12b, and the irradiation range in the channel direction is adjusted by the position and direction of the collimator 12c.

As shown in the left figure of FIG. 19, for example, it is conceivable that the imaging portion is deviated from the FOV center before the movement control. In this case, the X-ray irradiation range is set wide so as to include an imaging region deviated from the center of the FOV. For example, in this case, the X-rays are set to be emitted from the X-ray tube 12a at an angle θ1.

On the other hand, as shown in the right figure of FIG. 19, the imaging portion is located near the center of the FOV after the movement control. In this case, the X-ray irradiation range can be set to a narrower range as compared with the case where the X-ray irradiation range is deviated from the FOV center. For example, in this case, the X-ray can be set to be emitted from the X-ray tube 12a at an angle θ2 narrower than the angle θ1.

Therefore, the setting function 37f sets the range of the FOV based on the position of the imaging portion after the movement control is executed. For example, the setting function 37f calculates the position of the imaging portion after the movement control is executed, based on the three-dimensional positioning image data and the movement amount by the movement control. Then, the setting function 37f sets the range of the FOV so that the imaging portion is included at the calculated position. Specifically, the setting function 37f sets the range of the FOV by adjusting the wedge 12b and the collimator 12c.

As described above, the X-ray CT apparatus 1 according to the fourth embodiment sets an appropriate FOV range according to the position of the subject P after the alignment of the subject P after the alignment of the subject P. be able to. Therefore, the X-ray CT apparatus 1 can reduce the exposure dose to the subject P, for example.

(Fifth Embodiment)
In the above embodiment, the case where the X-ray CT apparatus 1 adjusts the subject P has been described, but the embodiment is not limited to this. For example, the X-ray CT apparatus 1 may correct the position of the reconstruction center in the image reconstruction circuit 36.

FIG. 20 is a block diagram showing a configuration example of the processing circuit 37 of the X-ray CT apparatus 1 according to the fifth embodiment. The X-ray CT apparatus 1 according to the fifth embodiment has the same configuration as the X-ray CT apparatus 1 illustrated in FIG. 2, except that the processing circuit 37 shown in FIG. 20 is provided. Therefore, in the fifth embodiment, the points different from those in the first embodiment will be mainly described, and the same functions as those in the configuration described in the first embodiment are the same as those in FIG. The reference numerals are given and the description thereof will be omitted.

As shown in FIG. 20, the processing circuit 37 according to the fourth embodiment executes the detection function 37a, the position matching function 37b, the reception function 37c, and the correction function 37g. Here, since the detection function 37a, the position matching function 37b, and the reception function 37c are the same as the configurations described in the first embodiment, the description thereof will be omitted.

The correction function 37g corrects the position of the reconstruction center in the image reconstruction circuit 36 based on the difference between the position of the imaging portion included in the three-dimensional positioning image data and the center of the imaging field of view. Here, a case where the positioning image shown in the left figure of FIG. 13 is obtained when the brain is the imaging site will be described. In this case, the correction function 37g refers to the alignment-related information illustrated in FIG. 11 and obtains information on the representative point “center of gravity of the skull” corresponding to the imaging site “brain” and information on the predetermined position “FOV center”. get.

Subsequently, the correction function 37g calculates the position of the center of gravity of the skull in the three-dimensional positioning image data of the subject P. Specifically, the correction function 37g identifies the position of the skull from a plurality of positions detected by the detection function 37a. Then, the correction function 37g calculates the position of the center of gravity of the skull by calculating the center of gravity of the three-dimensional coordinates of each pixel (voxel) specified as the position of the skull.

Then, the correction function 37g calculates the difference between the calculated position of the center of gravity of the skull and the position of the center of the FOV. Here, for example, when the position of the center of gravity of the skull is deviated 1 cm to the right from the position of the FOV center, the correction function 37 g moves the position of the reconstruction center to the right by 1 cm. Then, the correction function 37g causes the image reconstruction circuit 36 to reconstruct the image data for diagnosis by using the reconstruction center after the movement.

As described above, the correction function 37g corrects the position of the reconstruction center in the image reconstruction circuit 36 based on the difference between the position of the imaging portion included in the three-dimensional positioning image data and the center of the imaging field of view. As a result, the X-ray CT apparatus 1 can obtain an image with good image quality without re-imaging, for example, even if the position of the subject P is deviated from the center of the FOV.

In the fifth embodiment, the case where the movement control by the movement control function 37d is not executed has been described, but the present invention is not limited to this. That is, when the X-ray CT apparatus 1 according to the fifth embodiment further includes the above-mentioned movement control function 37d, the movement control by the movement control function 37d and the correction of the reconstruction center by the correction function 37g are simultaneously applied. can do.

(Other embodiments)
In addition to the above-described embodiments, various different embodiments may be implemented.

(Movement control of pedestal)
In the above embodiment, the case where the movement control function 37d executes the movement control of the top plate 22 has been described, but the embodiment is not limited to this. For example, the positional relationship between the representative point and the predetermined position is relative. Therefore, if the gantry 10 is movable, the movement control function 37d may, for example, bring the top plate 22 closer to the gantry 10 so that the representative point and the predetermined position coincide with each other. May be brought closer to the top plate 22. Further, the movement control function 37d may move the top plate 22 and the gantry 10 at the same time to bring them closer to each other. That is, the movement control function 37d executes movement control for moving at least one of the top plate 22 and the gantry 10 so that the position of the imaging portion included in the three-dimensional positioning image data and the center of the imaging field of view are close to each other.

Further, for example, the movement control function 37d may adjust the orientation of the imaging portion in the FOV by controlling the tilt angle of the gantry 10. For example, the movement control function 37d may determine the tilt angle along the reference line in photographing the head, and may operate the gantry 10 at the determined tilt angle.

(Movement control using the center of gravity of the imaging site)
Further, in the above embodiment, the case where the imaging region is brought closer to the FOV center by moving the representative point representing the position of the imaging region to a predetermined position has been described, but the embodiment is not limited to this. .. For example, the movement control function 37d may calculate the position of the center of gravity of the imaging portion as the position of the imaging portion, and execute the movement control so that the calculated position of the center of gravity and the center of the FOV are close to each other.

For example, the case where the brain is the imaging site will be described. In this case, the movement control function 37d identifies the position of the brain from the plurality of positions detected by the detection function 37a. Then, the movement control function 37d calculates the position of the center of gravity of the brain (the center of gravity of the absorption amount) by calculating the center of gravity of the three-dimensional coordinates of each pixel (voxel) specified as the position of the brain. Then, the movement control function 37d moves the top plate 22 so that the calculated position of the center of gravity of the brain coincides with the position of the center of the FOV.

In this way, the movement control function 37d can bring the imaging region closer to the center of the FOV without necessarily setting a representative point.

(Presentation of options for imaging site)
Further, for example, the operator may be presented with options for the imaging region. For example, the reception function 37c presents a plurality of candidates as options when there are a plurality of candidates for the imaging region.

FIG. 21 is a diagram for explaining the processing in the reception function 37c according to the other embodiment. FIG. 21 illustrates a case where an imaging plan for imaging the head is selected, but there are “brain” and “orbit” as candidates for imaging sites.

In this case, as shown in FIG. 21, the reception function 37c displays, for example, a window 40 for displaying options on the display 32. The window 40 includes three options: "1. brain", "2. orbit", and "3. do not photograph". Here, when any option is specified by the operator, the subsequent processing is executed according to the specified option. For example, when "1. Brain" is selected, the movement control function 37d performs movement control for aligning the brain with the FOV center. When "2. Orbit" is selected, the movement control function 37d performs movement control for aligning the orbit to the center of the FOV. When "3. Do not shoot" is selected, the processing circuit 37 takes a picture without executing the movement control.

As described above, when there are a plurality of candidates for the imaging region, the reception function 37c can present a plurality of candidates as options.

(Correction of sagging amount of top plate)
Further, the movement control function 37d may correct the amount of sagging of the top plate 22. For example, the movement control function 37d calculates the amount of sagging of the top plate 22 from the three-dimensional positioning image data. Then, the movement control function 37d corrects the sagging amount of the top plate 22 by moving the top plate 22 upward by the calculated sagging amount.

(Maximum movement amount setting)
Further, for example, the movement control function 37d may set the maximum movement amount of the top plate 22 by using the three-dimensional positioning image data. For example, in the imaging of the lung field, the imaging is performed in a posture in which the subject P is raising his arm (arm raising). In this case, the movement control function 37d can estimate the posture of the subject P based on the three-dimensional positioning image data. Then, the movement control function 37d uses the estimated posture of the subject P to set the maximum movement amount of the top plate 22 within a range in which the subject P does not come into contact with the inner wall of the opening of the gantry 10.

Further, for example, the movement control function 37d may notify the operator by a warning or the like if the subject P may come into contact with the inner wall of the opening of the gantry 10.

(Calculation of tube current)
Further, for example, the scan control circuit 33 may control the tube current supplied to the X-ray tube 12a according to the position of the subject P in the FOV.

For example, the scan control circuit 33 determines the tube current for each local view according to the degree of deviation (offset) of the subject P from the center position of the FOV. Then, the scan control circuit 33 irradiates X-rays using the determined tube current for each local view.

In this way, the scan control circuit 33 can control the tube current supplied to the X-ray tube 12a according to the position of the subject P in the FOV. Therefore, for example, the X-ray CT apparatus 1 can irradiate an appropriate dose of X-rays according to the deviation even if the imaging is started with the position of the subject P deviated from the center of the FOV.

Further, each component of each of the illustrated devices 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 dispersed / physically distributed in an arbitrary unit according to various loads and usage conditions. It can be integrated and configured. Further, each processing function performed by each device may be realized by a CPU and a program analyzed and executed by the CPU, or may be realized as hardware by wired logic.

Further, among the processes described in the first to fifth embodiments and the modified examples, all or a part of the processes described as being automatically performed can be manually performed, or can be performed manually. It is also possible to automatically perform all or part of the processing described as being performed manually by a known method. In addition, the processing procedure, control procedure, specific name, and information including various data and parameters shown in the above document and drawings can be arbitrarily changed unless otherwise specified.

In addition, the methods described in the first to fifth embodiments and modifications can be realized by executing a program prepared in advance on a computer such as a personal computer or a workstation. This method can be distributed via a network such as the Internet. This method can also be performed by recording on a computer-readable recording medium such as a hard disk, flexible disk (FD), CD-ROM, MO, or DVD, and reading from the recording medium by the computer.

According to at least one embodiment described above, the alignment can be performed accurately.

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 X-ray CT device 10 Stand 22 Top plate 36 Image reconstruction circuit 37 Processing circuit 37a Detection function 37c Reception function 37d Movement control function

Claims (10)

A gantry that irradiates the subject with X-rays and detects the X-rays that have passed through the subject.
A top plate on which the subject is placed and inserted into the field of view of the gantry,
In the positioning imaging, a reconstruction unit that reconstructs the positioning image data from the X-ray data detected by the gantry, and
Using the anatomical feature points in the positioning image data, a detection unit that detects a plurality of sites in the subject included in the positioning image data, and a detection unit.
A reception unit that accepts multiple settings for imaging sites in the subject in a single examination,
The included in the positioning image data, and, in each of the shooting of a plurality of said imaging regions that will be set based on the feature point, taken in the order along the longitudinal direction of the top plate, and, for each imaging region A movement control unit that executes movement control for moving at least one of the top plate and the gantry so that a representative point representing the position and a predetermined position set based on the center of the photographing field of view coincide with each other .
An update unit that records the change in the position of the representative point by the operator and updates the predetermined position based on the recorded changed position.
Equipped with a,
The movement control unit executes the movement control so that the representative point set based on the feature point and the updated predetermined position coincide with each other.
X-ray CT device. The movement control unit executes the movement control so that a representative point set based on the feature point of a portion where the pixel value in the positioning image data is different from the peripheral portion coincides with the predetermined position. ,
The X-ray CT apparatus according to claim 1 . The movement control unit calculates the position of the center of gravity of the imaging portion as the position of the imaging portion, and executes the movement control so that the calculated position of the center of gravity and the center of the imaging field of view are close to each other.
The X-ray CT apparatus according to claim 1. A setting unit for setting the range of the imaging field of view based on the position of the imaging portion after the movement control is executed is further provided.
The X-ray CT apparatus according to any one of claims 1 to 3 . A correction unit for correcting the position of the reconstruction center in the reconstruction unit based on the difference between the position of the imaging portion included in the positioning image data and the center of the imaging field of view is further provided.
The X-ray CT apparatus according to any one of claims 1 to 4 . The reception unit receives an execution instruction to execute the movement control from the operator, and receives the execution instruction.
The movement control unit executes the movement control when the reception unit receives the execution instruction.
The X-ray CT apparatus according to any one of claims 1 to 5 . The reception unit receives a part designation instruction from the operator to specify the imaging part, and receives the instruction.
When the reception unit receives the part designation instruction, the movement control unit controls the movement so that the position of the imaging part designated by the received part designation instruction and the center of the imaging field of view come close to each other. Execute,
The X-ray CT apparatus according to any one of claims 1 to 6 . The movement control unit estimates the body shape of the subject based on the position of the body surface of the subject, and corrects the movement amount in the movement control according to the estimated body shape.
The X-ray CT apparatus according to any one of claims 1 to 7 . The movement control unit calculates the amount of sagging of the top plate from the positioning image data, and moves the top plate according to the calculated amount of sagging.
The X-ray CT apparatus according to any one of claims 1 to 8 . The positioning image data is three-dimensional medical image data.
The X-ray CT apparatus according to any one of claims 1 to 9 .