JP2017217154A - X-ray CT apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute accurate positioning.SOLUTION: An X-ray CT apparatus has a cradle, a top board, a reconstruction part, a detection part, a reception part and a movement control part. The cradle irradiates a subject with X-rays and detects X-rays transmitting through the subject. The top board for placing the subject on it is inserted into an imaging field of the cradle. The reconstruction part reconstructs positioning image data from data on the X-rays detected by the cradle in positioning imaging. The detection part detects each of a plurality of sections of the subject included in the positioning image data. The reception part receives setting of an imaging section of the subject. The movement control part executes movement control to move at least either the top board or the cradle so that the position of the imaging section included in the positioning image data and the center of the imaging field come close to each other.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to an X-ray CT apparatus.

  Conventionally, in an X-ray CT apparatus, prior to imaging of a diagnostic image, alignment is performed in order to place a subject at a position appropriate for imaging. For example, the operator of the X-ray CT apparatus lies the subject on the top of the bed apparatus and operates the bed apparatus to insert the top board into the gantry. Further, for example, the operator browses the positioning image and moves the subject so that the imaging region is located near the center of the FOV (Field Of View).

JP 2014-138909 A JP 2009-261915 A

  The problem to be solved by the present invention is to provide an X-ray CT apparatus capable of performing alignment accurately.

  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 transmitted through the subject. The top plate mounts the subject and is inserted into the imaging field of view of the gantry. The reconstruction unit reconstructs positioning image data from X-ray data detected by the gantry in positioning imaging. The detection unit detects each of a plurality of portions in the subject included in the positioning image data. The accepting unit accepts setting of an imaging region 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 region included in the positioning image data and the center of the imaging field of view approach each other.

FIG. 1 is a diagram illustrating an example of a configuration of a medical information processing system according to the first embodiment. FIG. 2 is a diagram illustrating an example of the configuration of the X-ray CT apparatus according to the first embodiment. FIG. 3 is a view for explaining three-dimensional scano image capturing by the scan control circuit according to the first embodiment. FIG. 4A is a diagram for explaining an example of a part detection process by the detection function according to the first embodiment. FIG. 4B is a diagram for explaining an example of a part detection process by the detection function according to the first embodiment. FIG. 5 is a diagram for explaining an example of a part detection process by the detection function according to the first embodiment. FIG. 6 is a diagram for explaining an example of a part detection process by the detection function according to the first embodiment. FIG. 7 is a diagram illustrating 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 illustrating a scan range conversion example by coordinate conversion according to the first embodiment. FIG. 10 is a flowchart showing a processing procedure performed by a conventional X-ray CT apparatus. FIG. 11 is a diagram illustrating an example of alignment related information stored in the storage circuit according to the first embodiment. FIG. 12 is a diagram for explaining processing by the movement control function according to the first embodiment. FIG. 13 is a diagram for explaining processing by the movement control function according to the first embodiment. FIG. 14 is a flowchart illustrating a processing procedure performed by the X-ray CT apparatus according to the first embodiment. FIG. 15 is a block diagram illustrating 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 processing by the update function according to the second embodiment. FIG. 17 is a flowchart illustrating a processing procedure performed by the X-ray CT apparatus according to the third embodiment. FIG. 18 is a block diagram illustrating 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 illustrating 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 another embodiment.

  Embodiments of an X-ray CT (Computed Tomography) apparatus will be described below 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 actually, a plurality of server devices and terminal devices can be included. The medical information processing system 100 can also include a medical image diagnostic apparatus such as an X-ray diagnostic apparatus, an MRI (Magnetic Resonance Imaging) apparatus, or an ultrasonic diagnostic apparatus.

(First embodiment)
FIG. 1 is a diagram illustrating an example of a configuration of a medical information processing system 100 according to the first embodiment. As illustrated in FIG. 1, the medical information processing system 100 according to the first embodiment includes an X-ray CT apparatus 1, a server apparatus 2, and a terminal apparatus 3. The X-ray CT apparatus 1, the server apparatus 2, and the terminal apparatus 3 are in a state in which they can communicate with each other directly or indirectly through, for example, a 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 according to 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), etc. are introduced to manage various information. For example, the terminal device 3 transmits an inspection order created along the above-described system to the X-ray CT apparatus 1 or the server apparatus 2. The X-ray CT apparatus 1 acquires patient information from an examination order received directly from the terminal apparatus 3 or a patient list (modality work list) for each modality created by the server apparatus 2 that has received the examination order. X-ray CT image data is collected every time. Then, the X-ray CT apparatus 1 transmits the collected X-ray CT image data and image data generated by performing various image processing on the X-ray CT image data to the server apparatus 2. The server apparatus 2 stores the X-ray CT image data and image data received from the X-ray CT apparatus 1, generates image data from the X-ray CT image data, and responds to an acquisition request from the terminal apparatus 3. 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 department in the hospital and is operated by a doctor who works in each department, such as a PC (Personal Computer), a tablet PC, a PDA (Personal Digital Assistant), a mobile phone, etc. It is. For example, in the terminal device 3, medical record information such as a patient's symptom and a doctor's findings is input by a doctor. Further, the terminal device 3 receives an inspection order for ordering an inspection by the X-ray CT apparatus 1, and transmits the input inspection order to the X-ray CT apparatus 1 and the server apparatus 2. That is, the doctor in the medical department operates the terminal device 3 to read the reception information of the patient who has visited the hospital and information on the electronic medical record, examines the corresponding patient, and inputs the medical record information to the read electronic medical record. Then, the doctor in the medical department operates the terminal operation 3 according to the necessity of the examination by the X-ray CT apparatus 1 and transmits the examination order.

  The server apparatus 2 stores medical images (for example, X-ray CT image data and image data collected by the X-ray CT apparatus 1) collected by the medical image diagnostic apparatus, and performs various image processing on the medical images. For example, a PACS server or the like. For example, the server device 2 receives a plurality of examination orders from the terminal device 3 arranged in each medical department, creates a patient list for each medical image diagnostic device, and uses the created patient list as each medical image diagnostic device. Send to. For example, the server apparatus 2 receives an examination order for performing an examination by the X-ray CT apparatus 1 from the terminal apparatus 3 of each clinical department, creates a patient list, and creates the created patient list as an X-ray. Transmit to the CT apparatus 1. And the server apparatus 2 memorize | stores the X-ray CT image data and image data which were collected by the X-ray CT apparatus 1, and according to the acquisition request from the terminal device 3, X-ray CT image data and image data are stored in the terminal apparatus. 3 to send.

  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. Transmit to device 2. FIG. 2 is a diagram illustrating 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 gantry 10, a bed 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 them to the console 30. The gantry 10 and the X-ray irradiation control circuit 11 generate X-rays. The apparatus 12 includes a detector 13, a data acquisition circuit (DAS) 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 interposed therebetween, and is rotated at a high speed in a circular orbit around the subject P by a gantry driving circuit 16 described later. It is an annular frame.

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

  The X-ray irradiation control circuit 11 switches the wedge 12b. The X-ray irradiation control circuit 11 adjusts the X-ray irradiation range (fan angle and cone angle) by adjusting the aperture of the collimator 12c. In addition, this embodiment may be a case where an operator manually switches a plurality of types of wedges.

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

  The X-ray tube 12 a is a vacuum tube that irradiates the subject P with an X-ray beam with a high voltage supplied by a high voltage generator (not shown). The X-ray beam is applied to the subject P as the rotating frame 15 rotates. Irradiate. 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 12 a continuously exposes X-rays around the subject P for full reconstruction or exposure that can be reconfigured for half reconstruction. It is possible to continuously expose X-rays in the irradiation range (180 degrees + fan angle). Further, the X-ray irradiation control circuit 11 can control the X-ray tube 12a to intermittently emit X-rays (pulse X-rays) at a preset position (tube position). The X-ray irradiation control circuit 11 can also modulate the intensity of the X-rays emitted 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 from the X-ray tube 12a at a range other than the specific tube position. Reduce the intensity of the emitted X-rays.

  The wedge 12b is an X-ray filter for adjusting the X-ray dose of X-rays emitted 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 irradiated from the X-ray tube 12a to the subject P have a predetermined distribution. Attenuating filter. For example, the wedge 12b is a filter obtained by processing aluminum so as to have a predetermined target angle or 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 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 driving circuit 16 rotates the rotary frame 15 to rotate the X-ray generator 12 and the detector 13 on a circular orbit around the subject P.

  The detector 13 is a two-dimensional array type detector (surface detector) that detects X-rays transmitted through the subject P, and a detection element array 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 includes 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 transmitted through the subject P over a wide range, such as a 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 collection circuit 14 generates projection data by performing amplification processing, A / D conversion processing, inter-channel sensitivity correction processing, and the like on the X-ray intensity distribution data detected by the detector 13. The projected data is transmitted to the console 30 described later. For example, when X-rays are continuously emitted from the X-ray tube 12a while the rotary frame 15 is rotating, the data acquisition circuit 14 collects projection data groups for the entire circumference (for 360 degrees). Further, the data collection circuit 14 associates the tube position with each collected projection data and transmits it to the console 30 described later. The tube position is information indicating the projection direction of the projection data. Note that the sensitivity correction processing between channels may be performed by the preprocessing circuit 34 described later.

  The couch device 20 is a device on which the subject P is placed, and includes a couch driving device 21 and a top plate 22 as shown in FIG. The couch driving device 21 moves the subject P into the rotary frame 15 by moving the top 22 in the Z-axis direction (longitudinal direction of the top 22). The top plate 22 is a plate on which the subject P is placed. That is, the top plate 22 is placed on the subject P and inserted into the FOV (Field Of View) of the gantry 10.

  For example, the gantry 10 executes a helical scan that rotates the rotating frame 15 while moving the top plate 22 to scan the subject P in a spiral shape. Alternatively, the gantry 10 performs a conventional scan in which the subject P is scanned in a circular orbit by rotating the rotating frame 15 while the position of the subject P is fixed after the top plate 22 is moved. Alternatively, the gantry 10 performs a step-and-shoot method in which the position of the top plate 22 is moved at regular intervals and a conventional scan is performed in a plurality of scan areas.

  The console 30 is a device that accepts an operation of the X-ray CT apparatus 1 by an operator and reconstructs X-ray CT image data using 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 includes a mouse, a keyboard, a trackball, a switch, a button, a joystick, and the like that are used by the operator of the X-ray CT apparatus 1 to input various instructions and settings, and instructions and settings information received from the operator. Is transferred to the processing circuit 37. For example, the input circuit 31 receives imaging conditions for X-ray CT image data, reconstruction conditions for reconstructing X-ray CT image data, image processing conditions for X-ray CT image data, and the like from the operator. The input circuit 31 receives an operation for selecting an examination for the subject. Further, the input circuit 31 accepts a designation operation for designating a part on the image.

  The display 32 is a monitor that is referred to by the operator, and displays image data generated from the X-ray CT image data to the operator under the control of the processing circuit 37, or the operator via the input circuit 31. A GUI (Graphical User Interface) for accepting various instructions, various settings, and the like is displayed. The display 32 displays a plan screen for a scan plan, a screen being scanned, and the like. Further, the display 32 displays a virtual patient image, image data, and the like including exposure information. The virtual patient image displayed on 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 driving circuit 16, the data acquisition circuit 14, and the bed driving device 21 under the control of the processing circuit 37, thereby Control the collection process. Specifically, the scan control circuit 33 controls projection data collection processing in positioning imaging for collecting positioning images (scano images) and main imaging (main scanning) for collecting images used for diagnosis. Here, in the X-ray CT apparatus 1 according to the first embodiment, a two-dimensional scanogram and a three-dimensional scanogram can be taken.

  For example, the scan control circuit 33 fixes the X-ray tube 12a at a position of 0 degree (a position in the front direction with respect to the subject) and continuously performs imaging 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 degree and moves the top plate 22 intermittently, while repeating the imaging intermittently in synchronization with the top plate movement. Take a scano image. Here, the scan control circuit 33 can capture a positioning image not only from the front direction but also from an arbitrary direction (for example, a side surface direction) with respect to the subject.

  The scan control circuit 33 captures a three-dimensional scanogram by collecting projection data for the entire circumference of the subject in the scanogram image capture. FIG. 3 is a view for explaining three-dimensional scano image shooting 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 a helical scan or a non-helical scan. Here, the scan control circuit 33 executes a helical scan or a non-helical scan with a lower dose than the main imaging over a wide range such as the entire chest, abdomen, the entire upper body, and the whole body of the subject. As the non-helical scan, for example, the above-described step-and-shoot scan is executed.

  As described above, the scan control circuit 33 collects projection data for the entire circumference of the subject, so that an image reconstruction circuit 36 described later reconstructs three-dimensional X-ray CT image data (volume data). As shown in FIG. 3, a positioning image can be generated from an arbitrary direction using the reconstructed volume data. Here, whether the positioning image is photographed two-dimensionally or three-dimensionally may be set arbitrarily by the operator, or may be preset according to the examination contents.

  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 acquired by the main photographing, and the storage circuit 35. To store.

  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 diagnostic projection data collected by the main imaging. The storage circuit 35 stores image data and a virtual patient image generated by an image reconstruction circuit 36 described later. Further, the storage circuit 35 appropriately stores a processing result by a 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 X-ray CT image data using the projection data stored in the storage circuit 35. Specifically, the image reconstruction circuit 36 reconstructs 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, for example, back projection processing. Further, as the back projection process, for example, a back projection process by an FBP (Filtered Back Projection) method can be cited. Alternatively, the image reconstruction circuit 36 can reconstruct the X-ray CT image data using a successive approximation method. The image reconstruction circuit 36 is an example of a 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 image data generated by various image processes in the storage circuit 35.

  The processing circuit 37 performs overall control of the X-ray CT apparatus 1 by controlling operations of the gantry 10, the couch device 20, and the console 30. Specifically, the processing circuit 37 controls the CT scan performed on the gantry 10 by controlling the scan control circuit 33. The processing circuit 37 controls the image reconstruction circuit 36 and the image generation process in the console 30 by controlling the image reconstruction circuit 36. In addition, 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 a detection function 37a, a position matching function 37b, a reception function 37c, and a 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 components of the processing circuit 37 shown in FIG. 2, is a program executable by the computer. It is recorded in the storage circuit 35 in the form. The processing circuit 37 is a processor that implements 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 a 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 parts in the subject included in the three-dimensional image data. Specifically, the detection function 37 a 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 feature point (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 indicating a feature of a part such as a specific bone, organ, blood vessel, nerve, or lumen. That is, the detection function 37a detects bones, organs, blood vessels, nerves, lumens, and the like included in the volume data by detecting anatomical feature points such as specific organs and bones. The detection function 37a can also detect positions of the head, neck, chest, abdomen, feet, etc. included in the volume data by detecting characteristic feature points of the human body. In addition, the site | part demonstrated by this embodiment means what included these positions in bones, organs, blood vessels, nerves, lumens, and the like. Hereinafter, an example of detection of a part 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 the textbook with the position of the feature point extracted from the volume data, thereby detecting the feature point extracted from the volume data. The inaccurate feature points are removed from the inside, and the positions of the feature points extracted from the volume data are optimized. Thereby, the detection function 37a detects each part of the subject included in the volume data. For example, the detection function 37a first extracts anatomical feature points included in the volume data using a supervised machine learning algorithm. Here, the above-described supervised machine learning algorithm is constructed using a plurality of supervised images in which correct anatomical feature points are manually arranged. For example, a decision forest is used. Is done.

  Then, the detection function 37a optimizes the extracted feature points by comparing a model indicating the three-dimensional positional relationship of anatomical feature points in the body with the extracted feature points. Here, the above-described model is constructed using the above-described teacher image, and for example, a point distribution model is used. That is, the detection function 37a includes 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 the points, the inaccurate feature points are removed and the feature points are optimized. That is, the detection function 37a detects a plurality of parts using 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 part detection process by the detection function 37a will be described with reference to FIGS. 4A, 4B, 5 and 6. FIG. 4A, 4B, 5 and 6 are diagrams for explaining an example of a part detection process by the detection function 37a according to the first embodiment. 4A and 4B, feature points are arranged two-dimensionally. Actually, feature points are arranged three-dimensionally. For example, the detection function 37a extracts voxels regarded as anatomical feature points (black dots in the figure) by applying a supervised machine learning algorithm to the volume data as shown in FIG. 4A. Then, the detection function 37a fits the position of the extracted voxel to a model in which the shape and positional relationship of the part, a point unique to the part, etc. are defined, as shown in FIG. Incorrect feature points are removed, and only voxels corresponding to more accurate feature points are extracted.

  Here, the detection function 37a gives an identification code for identifying the feature point indicating the feature of each part to the extracted feature point (voxel), and the identification code and position (coordinate) information of each feature point Is associated with the image data and stored in the storage circuit 35. For example, as shown in FIG. 4B, the detection function 37a gives identification codes such as C1, C2, and C3 to the extracted feature points (voxels). Here, the detection function 37 a attaches an identification code to each data subjected to the detection process, and stores the identification code in the storage circuit 35. Specifically, the detection function 37a is obtained from at least one projection data among the projection data of the positioning image, the projection data collected under non-contrast, and the projection data collected in a state of being imaged by the contrast agent. A part of the subject included in the reconstructed volume data is detected.

For example, as shown in FIG. 5, the detection function 37a attaches information in which the identification code is 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 store the storage circuit 35. To store. For 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 )” and the like are stored in association with the 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 such information.

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

For 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 diagnostic image, and, as shown in FIG. (X ′ ₁ , y ′ ₁ , z ′ ₁ ) ”,“ identification code: C2, coordinates (x ′ ₂ , y ′ ₂ , z ′ ₂ ) ”and the like are stored in association with the volume data. Further, the detection function 37a extracts the coordinates of the feature points from the volume data of the contrast phase out of the volume data of the diagnostic 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 ) ”and the like are stored in association with the volume data. Here, when feature points are extracted from volume data of contrast phase, feature points that can be extracted by being contrasted are included. For example, when the feature point is extracted from the volume data of the contrast phase, the detection function 37a can extract a blood vessel or the like contrasted with the contrast agent. Therefore, in the case of contrast phase volume data, as shown in FIG. 5, the detection function 37a has coordinates (x ′ ₃₁ , y ′ ₃₁ , z ′ ₃₁ ) to the coordinates of feature points such as blood vessels extracted by contrasting. Identification codes C31, C32, C33 and C34 for identifying each blood vessel are associated with the coordinates (x ′ ₃₄ , y ′ ₃₄ , z ′ ₃₄ ) and the like.

  As described above, the detection function 37a can identify which feature point is in which position in the volume data of the positioning image or the diagnostic image, and based on such information, an organ or the like Each part of can be detected. For example, the detection function 37a detects the position of the target part using information on the anatomical positional relationship between the target part to be detected and parts around the target part. For example, when the target region is “lung”, the detection function 37a acquires coordinate information associated with an identification code indicating the characteristics of the lung, and “rib”, “clavicle”, “heart” , Coordinate information associated with an identification code indicating a region around the “lung”, such as “diaphragm”. Then, the detection function 37a uses the information on the anatomical positional relationship between the “lung” and the surrounding site and the acquired coordinate information to extract the “lung” region in the volume data.

  For example, the detection function 37a uses the positional information such as “pulmonary apex: 2 to 3 cm above the clavicle”, “lower end of the lung: height of the seventh rib”, and the coordinate information of each part in FIG. As shown in FIG. 5, a region R1 corresponding to “lung” is extracted from the volume data. That is, the detection function 37a extracts the coordinate information of the voxel of 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 a region R2 corresponding to “heart” or the like in the volume data.

  The detection function 37a detects a position included in the volume data based on a feature point that defines the position of the head, chest, etc. in the human body. Here, the positions of the head and chest in the human body can be arbitrarily defined. For example, if the chest is defined from the seventh cervical vertebra to the lower end of the lung, the detection function 37a detects from the feature point corresponding to the seventh cervical vertebra to the feature point corresponding to the lower end of the lung as the chest. In addition, the detection function 37a can detect a site | part by various methods besides the method using the anatomical feature point mentioned above. For example, the detection function 37a can detect a part included in the volume data by a region expansion method based on a voxel value.

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

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

  In the virtual patient image stored by the storage circuit 35, these many anatomical feature points are detected in advance, and the position data of the detected feature points are attached to the virtual patient image data together with the identification codes of the respective feature points. Or it is stored in association. FIG. 7 is a diagram illustrating 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 storage circuit 35 has an identification code “V1”, “V2”, and identification codes 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 and the corresponding identification code in association with each other. For 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 feature point coordinates in association with each other. In FIG. 7, only the lung, heart, liver, stomach, kidney, and the like are shown as organs, but actually, the virtual patient image includes a larger number of organs, bones, blood vessels, nerves, and the like. . In FIG. 7, only the feature points corresponding to the identification codes “V1”, “V2”, and “V3” are shown, but actually more 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 using an identification code, and 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 assigned with identification codes indicating the same feature points between the feature points detected from the scanogram and the feature points detected from the virtual patient image. However, the embodiment is not limited to this, and matching can be performed using an arbitrary set of feature points.

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

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

  The position matching function 37b can convert the scan range specified on the virtual patient image into the scan range on the positioning image by the obtained coordinate conversion matrix “H”. For example, the position matching function 37b uses the coordinate transformation matrix “H” to change the scan range “SRV” designated 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 illustrating a scan range conversion example by coordinate conversion according to the first embodiment. For example, as shown on the virtual patient image in FIG. 9, when the operator sets the scan range “SRV” on the virtual patient image, the position matching function 37b uses the above-described coordinate transformation matrix to set the scan The range “SRV” is converted into a scan range “SRC” on the scanogram.

  Thereby, for example, the scan range “SRV” set so as to include the feature point corresponding to the identification code “Vn” on the virtual patient image has the identification code “Cn” corresponding to the same feature point on the scanogram. Is converted and set to a scan range “SRC”. Note that the above-described coordinate transformation matrix “H” may be stored in the storage circuit 35 for each subject and read and used as appropriate, or calculated every time a scanogram is collected. It may be the case. As described above, according to the first embodiment, the virtual patient image is displayed for the range designation at the time of presetting, and the position / range is planned on the virtual patient image, so that the positioning image (scano image) is captured. It is possible to automatically set numerical values for the position / range on the positioning image corresponding to the planned position / range.

  Returning to the description of FIG. 2, the processing circuit 37 executes a reception function 37 c and a movement control function 37 d to perform control for accurately aligning. Such control will be described in detail later.

  In FIG. 2, it is assumed that the processing functions performed by the detection function 37a, the position matching function 37b, the reception function 37c, and the movement control function 37d are realized by a single processing circuit 37. A processing circuit may be configured by combining independent processors, and the functions may be realized by each processor executing a program.

  The term “processor” used in the above description is, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an application specific integrated circuit (ASIC), a programmable logic device (for example, It means circuits such as a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), a field programmable gate array (FPGA), etc. The processor is a memory circuit. The function is realized by reading and executing the program stored in 35. Note that the program may be directly incorporated in the circuit of the processor instead of storing the program in the storage circuit 35. The processor realizes the function by reading and executing the program incorporated in the circuit, but each processor of the present embodiment is not limited to being configured as a single circuit for each processor, but a plurality of independent The circuits may be combined to form a single processor that implements the function, and the functions shown in Fig. 2 may be integrated into a single processor. .

  By the way, conventionally, prior to imaging for diagnosis (hereinafter also referred to as “main scan” as appropriate), the subject P is aligned. Here, the alignment means, for example, that the position of the subject P placed on the top 22 is adjusted to an appropriate position for imaging.

  FIG. 10 is a flowchart showing a processing procedure performed by a conventional X-ray CT apparatus. The X-ray CT apparatus is in a standby state until the inspection is started (Yes at Step S11). As shown in FIG. 10, when the inspection is started (Yes at Step S11), the operator performs alignment (Step S12). For example, an operator (such as a radiographer) lies the subject P on the top board 22 and operates the bed apparatus 20 to insert the top board 22 into the gantry 10. Subsequently, the operator performs shooting of 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 views the displayed positioning image and determines whether or not the position of the subject P is appropriate based on whether or not the imaging region is located near the center of FOV (Field Of View). Judging. Here, if it is determined that the position of the subject P is appropriate (Yes at Step S15), diagnostic imaging is performed (Step S16). Note that 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 (No at Step S15), the process returns to Step S12, and the operator performs alignment again. For example, the operator adjusts the vertical position of the imaging region by operating the bed apparatus 20 and moving the top plate 22 in the vertical direction. Further, for example, the operator adjusts the position of the imaging region 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 captured (step S13), and then the positioning image is reconstructed and displayed (step S14). As described above, the processes in steps S12 to S14 are repeatedly executed until it is determined that the position of the subject P is appropriate.

  Note that the processing procedure illustrated in FIG. 10 is merely an example. For example, the positioning image may not be captured repeatedly. For example, even if the operator performs the second alignment, the operator may perform diagnostic imaging without imaging the second positioning image. If the top plate 22 can be moved in the left-right direction, the operator may adjust the position of the imaging region 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 around the center of the FOV, it is difficult for an inexperienced operator to accurately align the subject P. Further, even an experienced operator may vary among operators.

  If the subject P is not correctly aligned, the image data captured in the main scan may be affected. For example, the closer to the center of the FOV, the stronger the dose of X-rays that are irradiated. Therefore, the greater the deviation from the center of the FOV, the more easily artifacts due to overflow occur. In addition, for example, if the alignment at the time of capturing the positioning image is not accurate, an error occurs in the X-ray dose set based on the positioning image, resulting in an influence on the image quality.

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

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

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

  As shown in FIG. 11, for example, the positioning related information stored in the storage circuit 35 includes an imaging plan “AAA”, an imaging region “brain”, a representative point “the center of gravity of the skull”, and a predetermined position “FOV”. It includes information associated with “center”. This information indicates that the brain is located at the center of the FOV when the imaging part of the imaging plan named “AAA” is “the brain” and “the center of gravity of the skull” and “the center of the FOV” match. The alignment related information stored in the storage circuit 35 includes an imaging plan “BBB”, an imaging region “orbit”, a representative point “the midpoint of the position of the eyes of both eyes”, and a predetermined position “FOV center”. Includes information associated with "3 cm above". This information is obtained when the imaging part of the imaging plan named “BBB” is “orbital” and “orbital position of both eyes” and “3cm above the center of FOV” coincide with each other. It represents being located at the center of the FOV. The alignment-related information stored in the storage circuit 35 includes an imaging plan “CCC”, an imaging region “left lung field”, a representative point “center of gravity of the left lung field”, and a predetermined position “FOV center”. "Is included. This information indicates that if the imaging part of the imaging plan named “CCC” is “left lung field” and the “center of gravity of the left lung field” matches “FOV center”, the left lung field is It represents being located at the center of the FOV. Further, the positioning related information stored in the storage circuit 35 can be included in the same manner for other photographing plans.

  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 photographing plan is illustrated, but the embodiment is not limited thereto. For example, instead of an imaging plan, information on an examination order from a doctor (such as an examination purpose) may be stored. In this case, the alignment related information is associated with each piece of inspection order information.

  The reception function 37c receives the setting of the imaging region in the subject P. For example, the reception function 37c receives an input for designating a shooting plan from the operator. Then, the reception function 37c refers to the positioning related information stored in the storage circuit 35, and receives information on the imaging region corresponding to the imaging plan specified by the received input. The reception function 37c is an example of a reception unit.

  For example, when the imaging plan “AAA” is designated by the operator, the reception function 37c refers to the positioning related information stored in the storage circuit 35, and the imaging function “BAA” corresponding to the imaging plan “AAA” is selected. Accept information.

  In addition, the reception function 37c receives an execution instruction to execute movement control of the top board 22 from the operator. For example, the reception function 37c displays on the display 32 a button indicating that the movement control of the top board 22 is executed and a button indicating that the movement control of the top board 22 is not executed. And the reception function 37c receives the instruction | indication whether the movement control of the top plate 22 is performed according to which button is designated by the operator.

  The movement control function 37d executes movement control for moving the top board 22 so that the position of the imaging region included in the positioning image data and the center of the imaging field of view approach each other. For example, the movement control function 37d executes movement control so that a representative point that represents the position of the imaging region set based on the feature point matches a predetermined position that is set based on the center of the imaging field of view. To do. Specifically, the movement control function 37d executes movement control so that the representative point set based on the feature point of the part whose pixel value in the positioning image data is different from the peripheral part matches the predetermined position. To do. The movement control function 37d is an example of a movement control unit.

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

  As shown in FIG. 12, the movement control function 37d performs control 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 left-right direction, and the rotation direction, and moves the top plate 22 within the range of the maximum movement amount. Here, the maximum movement amount in each direction is set so that the subject P or the top plate 22 does not contact the inner wall of the opening of the gantry 10 into which the subject P is inserted, for example.

  As illustrated in FIG. 13, the movement control function 37 d performs movement control of the top plate 22 based on the position of the imaging region in the positioning image. Here, a case where the positioning image shown in the left diagram of FIG. 13 is obtained when the brain is an imaging region will be described. In this case, the movement control function 37d refers to the positioning related information illustrated in FIG. 11, and information on the representative point “skull center of gravity” corresponding to the imaging region “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 specifies 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 22 so that the calculated position of the center of gravity of the skull matches 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 of the center of the FOV. In this case, the movement control function 37d moves the top plate 22 to the upper left in the figure, thereby matching the position of the center of gravity of the skull and the position of the FOV center as shown in the right figure of FIG.

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

  12 and 13 are only examples. For example, the predetermined portion 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 eye corners of both eyes” and the predetermined part “3 cm above the center of the FOV” coincide with each other when the imaging region is “orbit”. Control is executed (see FIG. 11). For example, the movement control function 37d may adjust the direction 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 22 within a range where the subject P does not fall.

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

In step S101, the processing circuit 37 determines whether or not an inspection has been started. For example, when an instruction to start the inspection is input by the operator, the processing circuit 37 starts the inspection and executes the processes after step S102. If step S101 is negative, 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 lies the subject P on the top plate 22 and operates the bed apparatus 20 to insert the top plate 22 into the gantry 10.

  In step S103, the scan control circuit 33 performs imaging of the positioning image. For example, the scan control circuit 33 captures a three-dimensional positioning image by collecting projection data for the entire circumference of the subject by helical scanning or non-helical scanning.

  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 capturing the positioning image.

  In step S105, the detection function 37a detects a part 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 anatomical feature points.

  In step S106, the processing circuit 37 displays a positioning image. For example, the processing circuit 37 generates and displays image data of a predetermined cross section (for example, the 0 degree direction and the 90 degree direction) 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 set in advance in an arbitrary direction of the operator.

  In step S <b> 107, the processing circuit 37 determines whether to perform movement control of the top plate 22. For example, the reception function 37c receives an instruction as to whether or not to execute movement control of the top board 22. And if the reception function 37c receives the instruction | indication which performs the movement control of the top plate 22, the processing circuit 37 will determine with performing the movement control of the top plate 22, and will transfer 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 board 22, the processing circuit 37 determines that the movement control of the top board 22 is not executed, and the process proceeds to step S110.

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

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

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

  FIG. 14 is only an example. For example, the above processing procedures do not necessarily have to be executed in the order described above. For example, the processes in steps S101 to S110 may be executed in a suitable order as long as the processing contents do not contradict each other. For example, the process of step S105 for detecting the part from the volume data may be executed in an arbitrary order as long as the process 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 positioning image data from X-ray data detected by the gantry 10 in positioning imaging. The detection function 37a detects each of a plurality of parts in the subject P included in the positioning image data. The reception function 37c receives the setting of the imaging region in the subject P. The movement control function 37d executes movement control for moving the top board 22 so that the position of the imaging region included in the positioning image data and the center of the imaging field of view approach each other. According to this, the X-ray CT apparatus 1 according to the first embodiment can perform alignment accurately.

  For example, since the X-ray CT apparatus 1 collects the projection data of the positioning image three-dimensionally, it collects more information regarding the positioning of the subject P with 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 in an arbitrary direction for the subject P and can accurately grasp the position of the subject P in the FOV. And by using the information on the position of the subject P, the X-ray CT apparatus 1 can perform alignment accurately. For example, the X-ray CT apparatus 1 can accurately align even an inexperienced operator.

  Further, for example, the X-ray CT apparatus 1 can improve the image quality of diagnostic image data by accurate alignment. For example, since the X-ray CT apparatus 1 automatically aligns the imaging region according to the inspection purpose with the FOV center, there is no variation among operators, and the image quality can be stabilized. Further, for example, the X-ray CT apparatus 1 can reduce artifacts due to overflow because the deviation from the center of the FOV is small. In addition, for example, the X-ray CT apparatus 1 can accurately calculate the dose of X-rays irradiated in the main scan by using the projection data of the positioning image three-dimensionally, thereby improving the image quality. Can do.

  In addition, for example, the X-ray CT apparatus 1 accurately aligns by taking a single positioning image and accurately calculates the X-ray dose. For this reason, since the X-ray CT apparatus 1 does not take two or more positioning images, the exposure amount of the subject P can be reduced and the examination time can be shortened.

  In addition, for example, the X-ray CT apparatus 1 performs movement control using representative points based on feature points of parts where pixel values (CT values) in the positioning image data are three-dimensionally different from the peripheral parts. 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 surfaces. According to this, the X-ray CT apparatus 1 can accurately specify the representative point in the positioning image data even if the positioning image data is collected at a low dose, for example. For this reason, the X-ray CT apparatus 1 can perform alignment accurately.

  In the above-described embodiment, the case where volume data that is three-dimensional medical image data is used as the positioning image data has been described. However, 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 a three-dimensional space.

(Modification of First Embodiment: Correction of Movement Amount According to 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 type 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 type.

  Here, a case where the imaging region 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 of the subject P as a body type index using the position of the identified abdominal body surface. Then, the movement control function 37d offsets the predetermined position in FIG. 11 by a predetermined amount in the predetermined direction when the calculated length of the waistline is somewhat different from the standard value. For example, the movement control function 37d offsets the predetermined position “FOV center” upward by several centimeters when the length of the waistline is longer than a standard value. As an example, the movement control function 37d corrects a predetermined position corresponding to the imaging region “left lung field” to “2 cm above the FOV center”.

  Thus, the movement control function 37d corrects the movement amount according to the body shape of the subject P. For this reason, the movement control function 37d can accurately align according to the body shape of the subject P.

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

  FIG. 15 is a block diagram illustrating 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 a configuration similar to that of the X-ray CT apparatus 1 illustrated in FIG. 2 and is different in that it includes a processing circuit 37 illustrated in FIG. Therefore, in the second embodiment, the description will focus on the differences from the first embodiment, and the same functions as those described in the first embodiment are the same as those in FIG. Reference numerals are assigned and description is omitted.

  As illustrated in FIG. 15, the processing circuit 37 according to the second embodiment includes the same configuration as the processing circuit 37 illustrated in FIG. 2, and further includes an update function 37 e. The update function 37e records a change in the position of the representative point by the operator, and updates a 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 for changing the position of the representative point from the operator. Specifically, the update function 37e receives an operation for changing the position of the imaging region with respect to the FOV on the positioning image displayed on the display 32 from the operator. As an example, after the movement control function 37d executes movement control so that the center of gravity of the skull coincides with the center of the FOV, the operator may further move the imaging region “down 1 cm”. In such a case, the update function 37e records an 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 for moving to “down 1 cm”. For example, in the positioning related information shown in FIG. 11, the predetermined position “FOV center” corresponding to the representative point “the center of gravity of the skull” is updated to “1 cm below the FOV center”. As a result, the update function 37e updates the positioning related information shown in FIG. 11 to the positioning related information shown in FIG. FIG. 16 is a diagram for explaining processing 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 of the position of the representative point by the operator, and the predetermined position based on the recorded changed position. Update. Then, the movement control function 37d executes movement control so that the representative point matches the predetermined position updated by the update function 37e. As a result, the X-ray CT apparatus 1 can improve the alignment accuracy of the imaging region.

(Third embodiment)
In the above-described embodiment, the case where one imaging region is imaged in one inspection 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 by one examination.

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

  The reception function 37c according to the third embodiment receives a plurality of imaging regions. In addition, the movement control function 37d according to the third embodiment is configured so that the position of each imaging region and the center of each imaging field of view become closer in each of the imaging of the plurality of imaging regions accepted by the reception function 37c. Execute movement control.

  FIG. 17 is a flowchart illustrating a processing procedure performed by the X-ray CT apparatus 1 according to the third embodiment. The processing procedure shown in FIG. 17 is started when the operator inputs an instruction to start inspection. In the processing procedure shown in FIG. 17, the processes in steps S201 to S207 are the same as the processes in steps S101 to S107 shown in FIG. 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.

  If step S207 is affirmed, in step S208, the reception function 37c receives a plurality of imaging regions. For example, the reception function 37c receives the designation of the imaging plans “AAA” and “CCC” from the operator for one examination. Then, the reception function 37c refers to the positioning related information illustrated in FIG. 11, and information on the imaging region “brain” corresponding to the imaging plan “AAA” and the imaging region “left” corresponding to the imaging plan “CCC”. "Lung field" information.

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

  For example, when imaging the brain in the first imaging and imaging the left lung field in the second imaging, the movement control function 37d first matches the position of the center of gravity of the skull with the position of the FOV center. As described above, the top plate 22 is moved to perform imaging of the brain. When the imaging of the brain is completed, the movement control function 37d moves the top 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 imaging of the left lung field. Let Here, when the height of the top plate 22 in the first shooting is different from the height of the top plate 22 in the second shooting, the movement control function 37d changes the longitudinal position of the top plate 22. The height of the top plate 22 may be changed. That is, in this case, the movement control function 37d linearly (obliquely) from the position of the top 22 at the time when the first photographing is completed to the position of the top 22 at the time when the second photographing is started. ) It may be moved.

  As described above, the X-ray CT apparatus 1 according to the third embodiment can be applied to a case where a plurality of imaging regions are imaged in one examination. Note that when imaging a plurality of imaging regions, the imaging order of each imaging region can be arbitrarily set, but it is preferable to perform imaging in the order along the longitudinal direction of the top board 22. For example, the X-ray CT apparatus 1 is preferably imaged in the order from the head to the lower limbs, or from the lower limbs to the head.

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

  FIG. 18 is a block diagram illustrating 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 is different from the X-ray CT apparatus 1 illustrated in FIG. 2 in that the processing circuit 37 illustrated in FIG. Therefore, the fourth embodiment will be described with a focus on differences from the first embodiment, and the same function as that of the configuration described in the first embodiment is the same as in FIG. Reference numerals are assigned and description is omitted.

  As illustrated 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 FOV range based on the position of the imaging region after the movement control is executed. The setting function 37f is an example of a setting unit.

  FIG. 19 is a diagram for explaining processing by the setting function 37f according to the fourth embodiment. In FIG. 19, the range of FOV before and after the movement control of the top plate 22 is illustrated. The FOV range is defined by, for example, the X-ray irradiation range. Specifically, the irradiation range in the X-ray slice direction is adjusted by the thickness and position of the wedge (bow tie 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 diagram of FIG. 19, for example, it is conceivable that the imaging region is deviated from the FOV center before the movement control. In this case, the X-ray irradiation range is set to be wide so as to include an imaging region deviated from the FOV center. For example, in this case, the X-ray is set to be irradiated from the X-ray tube 12a at an angle θ1.

  On the other hand, as shown in the right diagram of FIG. 19, after the movement control, the imaging region is located near the center of the FOV. In this case, the X-ray irradiation range can be set to a narrow range as compared with the case where it is shifted 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 FOV range based on the position of the imaging region after the movement control is executed. For example, the setting function 37f calculates the position of the imaging region 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 FOV range so that the imaging region is included at the calculated position. Specifically, the setting function 37f sets the FOV range by adjusting the wedge 12b and the collimator 12c.

  As described above, after aligning the subject P, the X-ray CT apparatus 1 according to the fourth embodiment sets an appropriate FOV range in accordance with the position of the subject P after the alignment. be able to. For this reason, the X-ray CT apparatus 1 can reduce the exposure amount with respect to the subject P, for example.

(Fifth embodiment)
In the above embodiment, the case where the X-ray CT apparatus 1 aligns 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 illustrating 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 is different from the X-ray CT apparatus 1 illustrated in FIG. 2 in that it includes a processing circuit 37 illustrated in FIG. Therefore, the fifth embodiment will be described with a focus on differences from the first embodiment, and the same function as that of the configuration described in the first embodiment is the same as in FIG. Reference numerals are assigned and description is omitted.

  As shown in FIG. 20, the processing circuit 37 according to the fourth embodiment executes a detection function 37a, a position matching function 37b, a reception function 37c, and a correction function 37g. Here, since the detection function 37a, the position collation function 37b, and the reception function 37c are the same as the structure demonstrated in 1st Embodiment, description is abbreviate | 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 region 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 diagram of FIG. 13 is obtained when the brain is an imaging region will be described. In this case, the correction function 37g refers to the positioning-related information illustrated in FIG. 11 and uses information on the representative point “center of the skull” corresponding to the imaging region “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 specifies the position of the skull from a plurality of positions detected by the detection function 37a. 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 FOV center. Here, for example, when the position of the center of gravity of the skull is shifted 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 diagnostic image data using the reconstructed center after the movement.

  Thus, 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 region 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 performing re-imaging even when the image of the subject P is imaged in a state of being 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. However, 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-described 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 embodiment, various other forms may be implemented.

(Mounting movement control)
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 configured to be movable, the movement control function 37d may bring the top plate 22 close to the gantry 10, for example, so that the representative point coincides with the predetermined position. May be brought closer to the top plate 22. In addition, the movement control function 37d may move the top plate 22 and the gantry 10 at the same time and bring them closer together. 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 region included in the three-dimensional positioning image data and the center of the imaging field of view approach each other.

  For example, the movement control function 37d may adjust the direction of the imaging region 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 and operate the gantry 10 at the determined tilt angle in photographing the head.

(Movement control using the center of gravity of the imaged part)
In the above embodiment, the case has been described in which the representative point representing the position of the imaging region is moved to a predetermined position to bring the imaging region closer to the FOV center. However, 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 part as the position of the imaging part, and execute the movement control so that the calculated position of the center of gravity and the center of the FOV approach each other.

  For example, a case where the brain is an imaging region will be described. In this case, the movement control function 37d specifies 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 absorption) 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 22 so that the calculated position of the center of gravity of the brain matches the position of the center of the FOV.

  As described above, 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 imaging part options)
In addition, for example, an imaging region option may be presented to the operator. 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 processing in the reception function 37c according to another embodiment. FIG. 21 exemplifies a case where there are “brain” and “orbit” as the candidate for the imaging region, although the imaging plan related to imaging of the head is selected.

  In this case, as illustrated in FIG. 21, the reception function 37 c displays, for example, a window 40 for displaying options on the display 32. This window 40 includes three options of “1. brain”, “2. orbit”, and “3. Here, when one of the options is designated by the operator, the subsequent processing is executed according to the designated option. For example, when “1. brain” is selected, the movement control function 37d performs movement control to position the brain around the FOV. When “2. Orbit” is selected, the movement control function 37d performs movement control for aligning the orbit around the FOV. When “3. Do not shoot” is selected, the processing circuit 37 performs shooting without executing movement control.

  In this manner, the reception function 37c can present a plurality of candidates as options when there are a plurality of candidates for imaging regions.

(Correction of the amount of sag of the top plate)
Further, the movement control function 37d may correct the sagging amount of the top board 22. For example, the movement control function 37d calculates the sag amount of the top board 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 travel setting)
Further, for example, the movement control function 37d may set the maximum movement amount of the top board 22 using three-dimensional positioning image data. For example, in lung field imaging, imaging is performed in a posture in which the subject P raises 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 22 within a range where the subject P does not contact 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 there is a possibility that the subject P is in contact with the inner wall of the opening of the gantry 10.

(Calculation of tube current)
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.

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

  Further, each component of each illustrated apparatus is functionally conceptual, and does not necessarily need to be physically configured as illustrated. In other words, the specific form of distribution / integration of each device is not limited to the one shown in the figure, and all or a part of the distribution / integration is functionally or physically distributed in arbitrary units according to various loads or usage conditions. Can be integrated and configured. Further, all or a part of each processing function performed in 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.

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

  The methods described in the first to fifth embodiments and the 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 executed by being recorded on a computer-readable recording medium such as a hard disk, a flexible disk (FD), a CD-ROM, an MO, and a DVD, and being read from the recording medium by the computer.

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

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

DESCRIPTION OF SYMBOLS 1 X-ray CT apparatus 10 Base 22 Top plate 36 Image reconstruction circuit 37 Processing circuit 37a Detection function 37c Reception function 37d Movement control function

Claims (14)

A platform for irradiating the subject with X-rays and detecting the X-rays transmitted through the subject;
Place the subject, a top plate to be inserted into the imaging field of view of the gantry,
In positioning imaging, a reconstruction unit that reconstructs positioning image data from X-ray data detected by the gantry;
A detection unit for detecting each of a plurality of sites in the subject included in the positioning image data;
A reception unit that receives a setting of an imaging region in the subject;
A movement control unit that performs movement control for moving at least one of the top plate and the gantry so that the position of the imaging region included in the positioning image data and the center of the imaging field of view approach each other, X Line CT device. The detection unit detects each of the plurality of parts using anatomical feature points in the positioning image data,
The movement control unit is configured to perform the movement control so that a representative point that represents the position of the imaging region set based on the feature point matches a predetermined position that is set based on the center of the imaging field of view. Run the
The X-ray CT apparatus according to claim 1. The movement control unit executes the movement control so that a representative point set based on the feature point of a part having a pixel value different from a peripheral part in the positioning image data matches the predetermined position. ,
The X-ray CT apparatus according to claim 2. An update unit that records a change in the position of the representative point by an operator and updates the predetermined position based on the recorded changed position;
The X-ray CT apparatus according to claim 2. The movement control unit calculates the position of the center of gravity of the imaging part as the position of the imaging part, and executes the movement control so that the calculated position of the center of gravity and the center of the imaging field of view approach each other.
The X-ray CT apparatus according to claim 1. The reception unit receives a plurality of the imaging parts,
The movement control unit executes the movement control so that the position of each imaging region and the center of the imaging field of view approach in each of the imaging of the plurality of imaging regions received by the reception unit.
The X-ray CT apparatus as described in any one of Claims 1-5. Further comprising a setting unit for setting a range of the imaging visual field based on the position of the imaging region after the movement control is executed,
The X-ray CT apparatus according to claim 1. A correction unit that corrects the position of the reconstruction center in the reconstruction unit based on the difference between the position of the imaging region included in the positioning image data and the center of the imaging field;
The X-ray CT apparatus as described in any one of Claims 1-7. The reception unit receives an execution instruction to execute the movement control from an operator,
The movement control unit executes the movement control when the receiving unit receives the execution instruction.
The X-ray CT apparatus according to claim 1. The reception unit receives a part designation instruction for designating the imaging part from an operator,
The movement control unit performs the movement control so that the position of the imaging region specified by the received region specification instruction and the center of the imaging field of view approach when the reception unit receives the region specification instruction. Run,
The X-ray CT apparatus as described in any one of Claims 1-9. The movement control unit estimates the body type 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 type.
The X-ray CT apparatus according to claim 1. The movement control unit calculates a sag amount of the top plate from the positioning image data, and moves the top plate according to the calculated sag amount.
The X-ray CT apparatus according to claim 1. The positioning image data is three-dimensional medical image data.
The X-ray CT apparatus according to claim 1. A platform for irradiating the subject with X-rays and detecting the X-rays transmitted through the subject;
Place the subject, a top plate to be inserted into the imaging field of view of the gantry,
In positioning imaging, a reconstruction unit that reconstructs positioning image data from X-ray data detected by the gantry;
A detection unit for detecting each of a plurality of sites in the subject included in the positioning image data;
A reception unit that receives a setting of an imaging region in the subject;
An X-ray CT apparatus comprising: a correction unit that corrects the position of the reconstruction center in the reconstruction unit based on a difference between the position of the imaging region included in the positioning image data and the center of the imaging field of view.