JP2013169359A - X-ray ct apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray CT apparatus capable of smoothing operations by automatically changing the direction of displaying an MPR (multi planar reconstruction) image.SOLUTION: An X-ray CT apparatus relating to the embodiment includes a collecting section, a volume data forming section, an MPR processing section, a transform processing section, and a display control section. The collecting section collects data by performing X-ray scanning of a subject placed on a bed device. The volume data forming section forms volume data on the basis of the collected data. The MPR processing section forms predetermined cross-section MPR image data by applying MPR processing to the formed volume data. The transform processing section applies affine transformation to the formed MPR image data. The display control section makes a display section display an MPR image based on the MPR image data obtained by the affine transformation.

Description

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

  An X-ray CT (Computed Tomography) device is a device that scans a subject with X-rays, collects data, and processes the collected data with a computer, thereby imaging the inside of the subject.

  Specifically, the X-ray CT apparatus emits X-rays to a subject a plurality of times from different directions, detects X-rays transmitted through the subject with an X-ray detector, and generates a plurality of detection data. collect. The collected detection data is A / D converted by the data collection unit and then transmitted to the data processing system. The data processing system forms projection data by pre-processing the detection data. Subsequently, the data processing system executes a reconstruction process based on the projection data to form tomographic image data. The data processing system forms volume data based on a plurality of tomographic image data as further reconstruction processing. The volume data is a data set representing a three-dimensional distribution of CT values corresponding to a three-dimensional region of the subject.

  The X-ray CT apparatus can perform MPR (Multi Planar Reconstruction) display by rendering volume data for an arbitrary cross section. The cross-sectional images (MPR images) displayed by MPR include orthogonal three-axis images, oblique images, and curved MPR images. An orthogonal triaxial image is an axial image showing a cross section orthogonal to the body axis, a sagittal image showing a cross section of the subject along the body axis, and a coronal showing a cross section of the subject along the body axis. Show the image. The oblique image is an image showing a cross section other than the orthogonal three-axis image. A curved MPR image (curved MPR image) is an image showing a curved cross section, and includes, for example, a cross-sectional image along the coronary artery, jawbone, and dentition of the heart. In addition, the X-ray CT apparatus renders volume data by setting an arbitrary line of sight, thereby forming a pseudo 3D image showing a form when the 3D region of the subject is viewed from this line of sight.

JP 2004-358267 A

  In image diagnosis, a plurality of MPR images may be displayed side by side or switched. In that case, it is desirable that the subject is drawn at the same position in the frame in the same direction and with the same magnification in the plurality of MPR images. In addition, the user may arbitrarily change the drawing position, drawing direction, and drawing magnification of the subject in the frame. In that case, in the conventional technique, the drawing position, drawing direction, and drawing magnification of the subject in the MPR image to be displayed have to be changed each time. This is a very time-consuming operation and has been one of the obstacles to the image browsing operation.

  Further, the posture of the subject at the time of imaging varies depending on the region to be imaged and the procedure, but the orientation of the displayed MPR image is the same. Specifically, there are a supine position, a prone position, and a lateral position (rightward and leftward) as positions in the rotational direction around the body axis, and an arrangement in which the head is directed toward the gantry device as the body position. There is an arrangement in which the foot is directed to the gantry device side. Despite the application of various postures, the MPR image was always displayed in the following manner: The axial image is displayed with the ventral side positioned on the upper side of the display screen and the back side positioned on the lower side. The sagittal image is displayed with the subject front on the left side of the display screen and the back side on the right side; the coronal image has the subject front on the front side of the display screen and the back side on the back side. It is displayed to be located. Such a display mode does not cause any particular inconvenience in simple image browsing. However, for example, when performing a puncturing operation for biopsy, the orientation of the subject that is actually visually recognized (that is, actual There is a difference between the orientation of the subject in the space and the orientation of the image, which hinders the smooth execution of the work.

  The problem to be solved by the present invention is to provide an X-ray CT apparatus capable of facilitating work by automatically changing the drawing mode of a subject in an MPR image.

  The X-ray CT apparatus according to the embodiment includes a collection unit, a volume data formation unit, an MPR processing unit, a conversion processing unit, and a display control unit. The collection unit scans the subject placed on the bed apparatus with X-rays and collects data. The volume data forming unit forms volume data based on the collected data. The MPR processing unit performs MPR processing on the formed volume data to form MPR image data of a predetermined section. The conversion processing unit performs affine transformation on the formed MPR image data. The display control unit causes the display unit to display an MPR image based on the MPR image data obtained by affine transformation.

It is a block diagram showing the structure of the X-ray CT apparatus which concerns on embodiment. It is a block diagram showing the structure of the X-ray CT apparatus which concerns on embodiment. It is a flowchart showing the operation example of the X-ray CT apparatus which concerns on embodiment. It is a block diagram showing the structure of the X-ray CT apparatus which concerns on embodiment. It is the schematic for demonstrating operation | movement of the X-ray CT apparatus which concerns on embodiment. It is a flowchart showing the operation example of the X-ray CT apparatus which concerns on embodiment. It is the schematic for demonstrating operation | movement of the X-ray CT apparatus which concerns on embodiment.

  An X-ray CT apparatus according to an embodiment will be described with reference to the drawings.

<First Embodiment>
[Constitution]
In this embodiment, an example in which affine transformation with the same magnification or the same affine transformation is performed on a plurality of MPR image data will be described. A configuration example of the X-ray CT apparatus according to this embodiment is shown in FIGS. In the following description, “image” and “image data” may be identified with each other.

  The X-ray CT apparatus 1 includes a gantry device 10, a bed device 30, and a console device 40.

(Mounting device)
The gantry device 10 is an apparatus that irradiates the subject E with X-rays and collects X-ray detection data transmitted through the subject E. The gantry device 10 includes an X-ray generator 11, an X-ray detector 12, a rotating body 13, a high voltage generator 14, a gantry driver 15, an X-ray diaphragm 16, a diaphragm driver 17, And a data collection unit 18.

  The X-ray generator 11 includes an X-ray tube that generates X-rays (for example, a vacuum tube that generates a cone-shaped or pyramid-shaped beam (not shown)). The generated X-rays are exposed to the subject E.

  The X-ray detection unit 12 includes a plurality of X-ray detection elements (not shown). The X-ray detection unit 12 detects X-ray intensity distribution data (hereinafter sometimes referred to as “detection data”) indicating the intensity distribution of X-rays transmitted through the subject E using a plurality of X-ray detection elements, The detected data is output as a current signal.

  As the X-ray detector 12, for example, a two-dimensional X-ray detector (surface detector) in which a plurality of detection elements are arranged in two directions (slice direction and channel direction) orthogonal to each other is used. The plurality of X-ray detection elements are provided, for example, in 320 rows along the slice direction. By using a multi-row X-ray detector in this way, a three-dimensional region having a width in the slice direction can be imaged with one scan (volume scan). The slice direction corresponds to the body axis direction of the subject E, and the channel direction corresponds to the rotation direction of the X-ray generation unit 11.

  The rotating body 13 is a member that supports the X-ray generation unit 11 and the X-ray detection unit 12 at positions facing each other with the subject E interposed therebetween. The rotating body 13 has an opening that penetrates in the slice direction. A top plate on which the subject E is placed is inserted into the opening. The rotating body 13 is rotated along a circular orbit centered on the subject E by the gantry driving unit 15.

  The high voltage generator 14 applies a high voltage to the X-ray generator 11. The X-ray generator 11 generates X-rays based on this high voltage. The X-ray diaphragm unit 16 forms a slit (opening), and changes the size and shape of the slit so that the X-ray fan angle (divergence angle in the channel direction) output from the X-ray generation unit 11 and the X-rays are changed. Adjust the cone angle (spreading angle in the slice direction). The diaphragm drive unit 17 drives the X-ray diaphragm unit 16 to change the size and shape of the slit.

  A data collection unit 18 (DAS: Data Acquisition System) collects detection data from the X-ray detection unit 12 (each X-ray detection element). Further, the data collection unit 18 converts the collected detection data (current signal) into a voltage signal, periodically integrates and amplifies the voltage signal, and converts it into a digital signal. Then, the data collecting unit 18 transmits the detection data converted into the digital signal to the console device 40.

  The collection unit 100 illustrated in FIG. 2 includes at least the gantry device 10. For example, when the bed apparatus 30 is driven at the time of scanning (at the time of data collection) like a helical scan, the bed apparatus 30 is also included in the collection unit 100.

(Bed apparatus)
A subject E is placed on a top plate (not shown) of the bed apparatus 30. The couch device 30 moves the subject E placed on the top plate in the body axis direction. Moreover, the couch device 30 moves the top plate in the vertical direction.

(Console device)
The console device 40 is used for operation input to the X-ray CT apparatus 1. Further, the console device 40 reconstructs CT image data (tomographic image data and volume data) representing the internal form of the subject E from the detection data input from the gantry device 10. The console device 40 includes a control unit 41, a scan control unit 42, a processing unit 43, a storage unit 44, a display unit 45, and an operation unit 46.

  The control unit 41, the scan control unit 42, and the processing unit 43 include, for example, a processing device and a storage device. As the processing apparatus, for example, a CPU (Central Processing Unit), a GPU (Graphic Processing Unit), or an ASIC (Application Specific Integrated Circuit) is used. The storage device is configured to include, for example, a ROM (Read Only Memory), a RAM (Random Access Memory), and an HDD (Hard Disc Drive). The storage device stores a computer program for executing the function of each unit of the X-ray CT apparatus 1. The processing device implements the above functions by executing these computer programs. The control unit 41 controls each unit of the apparatus. For example, the control unit 41 includes a display control unit 411 that controls the display unit 45 to display information (see FIG. 2).

  The scan control unit 42 integrally controls operations related to X-ray scanning. This integrated control includes control of the high voltage generation unit 14, control of the gantry driving unit 15, control of the aperture driving unit 17, and control of the bed apparatus 30. The control of the high voltage generator 14 is to control the high voltage generator 14 so that a predetermined high voltage is applied to the X-ray generator 11 at a predetermined timing. The control of the gantry driving unit 15 controls the gantry driving unit 15 so as to rotationally drive the rotating body 13 at a predetermined timing and a predetermined speed. The control of the diaphragm control unit 17 controls the diaphragm driving unit 17 so that the X-ray diaphragm unit 16 forms a slit having a predetermined size and shape. The control of the couch device 30 is to control the couch device 30 so that the top plate is moved to a predetermined position at a predetermined timing. In the volume scan, the scan is executed with the position of the top plate fixed. In the helical scan, the scan is executed while moving the top plate.

  The processing unit 43 performs various processes on the detection data transmitted from the gantry device 10 (data collection unit 18). The processing unit 42 includes a preprocessing unit 431, a reconstruction processing unit 432, a rendering processing unit 433, and a conversion processing unit 434.

  The preprocessing unit 431 performs preprocessing including logarithmic conversion processing, offset correction, sensitivity correction, beam hardening correction, and the like on the detection data from the gantry device 10 to generate projection data.

  The reconstruction processing unit 432 generates CT image data (tomographic image data or volume data) based on the projection data generated by the preprocessing unit 431. As the reconstruction processing of the tomographic image data, for example, any method such as a two-dimensional Fourier transform method or a convolution / back projection method can be applied. The volume data is generated by interpolating a plurality of reconstructed tomographic image data. As volume data reconstruction processing, for example, an arbitrary method such as a cone beam reconstruction method, a multi-slice reconstruction method, an enlargement reconstruction method, or the like can be applied. In the volume scan using the multi-row X-ray detector described above, a wide range of volume data can be reconstructed. The volume data forming process is performed by the volume data forming unit 432a shown in FIG.

  The rendering processing unit 433 can execute, for example, MPR processing and volume rendering. The MPR process is an image process for generating MPR image data representing a section by setting an arbitrary section to the volume data formed by the volume data forming unit 432a and performing a rendering process. The MPR process is executed by the MPR processing unit 433a shown in FIG. Volume rendering generates pseudo three-dimensional image data representing the three-dimensional region of the subject E by sampling volume data along an arbitrary line of sight (ray) and adding the values (CT values). Image processing.

  The conversion processing unit 434 performs affine transformation on the MPR image data formed by the MPR processing unit 433a. In particular, the conversion processing unit 434 performs similar affine transformation on each MPR image data when MPR image data is sequentially formed. The “similar affine transformation” includes not only the same affine transformation but also an affine transformation having a part of the characteristic. Here, “characteristic” means the influence of affine transformation on the target. Specifically, the affine transformation is a coordinate transformation performed on a parallel movement, a rotational movement, a magnification change, a reversal (or mirror image), etc., and its characteristics include a parallel movement amount, a rotational movement amount, a magnification change amount, There is a reverse direction. An example of such an affine transformation will be described below.

  As a first example, a case where affine transformation with the same magnification is applied to a plurality of MPR image data will be described. The affine transformation is expressed as a matrix, for example. The storage unit 44 stores information (magnification information) indicating a preset affine transformation magnification. The magnification information may be, for example, a matrix representing an affine transformation, or may be an absolute value (area or volume magnification) of a determinant of the matrix, or each direction (for example, x direction, y direction (, It may be a magnification in the z direction)). This affine transformation is arbitrarily set by the user, for example. Examples of setting methods include a method for setting affine transformation by specifying matrix components, a method for setting affine transformation by specifying each of the above characteristics, and an affine transformation by actually moving, rotating, or inverting an image. There is a method to set the conversion. These operations are performed using the operation unit 46 (and the display unit 45). The affine transformation to be set may be two-dimensional or three-dimensional. When the two-dimensional affine transformation is set, the two-dimensional affine transformation can be applied to other MPR image data having the same cross section as the MPR image data for which the two-dimensional affine transformation is set. It is possible to apply as affine transformation for other MPR image data and volume data having different cross sections. In addition, when the three-dimensional affine transformation is set, it can be applied to volume data or MPR image data of an arbitrary cross section.

  When new MPR image data is formed by the MPR processing unit 433a, the conversion processing unit 434 performs a new affine transformation for enlarging or reducing at a magnification indicated by the magnification information stored in the storage unit 44, as the new MPR. It is applied to image data. Thereby, an MPR image having the same magnification is automatically displayed.

  As a second example, a case where affine transformation with the same magnification is performed on a plurality of MPR image data will be described. The storage unit 44 stores information indicating affine transformation set in advance (affine transformation information). The affine transformation information is, for example, a matrix that represents the affine transformation. The matrix indicating the affine transformation substantially includes the magnification information of the first example (that is, the magnification can be calculated from the matrix). When new MPR image data is formed by the MPR processing unit 433a, the conversion processing unit 434 performs a new affine transformation using the affine transformation information stored in the storage unit 44 on the new MPR image data. Apply. Thereby, the MPR image subjected to the same conversion is automatically displayed. The “same transformation” means that the above characteristics of the affine transformation are all the same.

  Although two examples have been described here, other affine transformations having the same characteristics may be applied to a plurality of MPR image data, or affine transformations having the same combination of the above characteristics may be performed. You may make it apply to several MPR image data. Two or more affine transformations may be selectively applied.

  The storage unit 44 stores the magnification information and affine transformation information. The storage unit 44 stores detection data, projection data, image data after reconstruction processing, and the like. The display unit 45 is configured by a display device such as an LCD (Liquid Crystal Display). The operation unit 46 is used for inputting various instructions and information to the X-ray CT apparatus 1. The operation unit 46 includes, for example, a keyboard, a mouse, a trackball, a joystick, and the like. The operation unit 46 may include a GUI (Graphical User Interface) displayed on the display unit 45.

[Operation]
The operation of the X-ray CT apparatus 1 according to this embodiment will be described. An operation example of the X-ray CT apparatus 1 is shown in FIG.

(S1: Start collecting detection data)
First, the subject E is placed on the top plate of the bed apparatus 30 and inserted into the opening of the gantry apparatus 10. When a predetermined scan start operation is performed, the control unit 41 sends a control signal to the scan control unit 42. Upon receiving this control signal, the scan control unit 42 controls the high voltage generation unit 14, the gantry drive unit 15, and the aperture drive unit 17 to scan the subject E with X-rays. The X-ray detection unit 12 detects X-rays that have passed through the subject E. The data collection unit 18 collects detection data sequentially generated from the X-ray detector 12 along with the scan. The data collection unit 18 sends the collected detection data to the preprocessing unit 431.

(S2: Start generation of projection data)
The preprocessing unit 431 performs the above-described preprocessing on the detection data from the data collection unit 18 to generate projection data.

(S3: Start of volume data formation)
The reconstruction processing unit 432 performs reconstruction processing on the projection data generated by the preprocessing unit 431 to form a plurality of tomographic image data. Further, the volume data forming unit 432a forms volume data based on these tomographic image data.

(S4: Start of formation of MPR image data)
The MPR processing unit 433a forms MPR image data based on the volume data formed by the volume data forming unit 432a. This MPR image data may be any image data of orthogonal three-axis images, or may be image data of oblique images based on arbitrarily set cross sections.

(S5: MPR image display)
The display control unit 411 causes the display unit 45 to display an MPR image based on the MPR image data formed by the MPR processing unit 433a.

  At this stage, in order to reduce the exposure dose to the subject E, detection data collection, projection data generation, volume data formation, and MPR image data formation can be temporarily stopped. In that case, these processes can be restarted at an arbitrary timing before step 8.

(S6: Affine transformation setting)
The user sets affine transformation based on the displayed MPR image. As a specific example of this process, the user processes the displayed MPR image using the operation unit 46. This “processing” includes at least one of rotational movement, parallel movement, magnification change, and inversion (that is, affine transformation). The processing unit 43 obtains affine transformation corresponding to the processing content, and generates magnification information or affine transformation information based on the affine transformation.

(S7: Storage of magnification information / affine transformation information)
The control unit 41 stores the magnification information or affine transformation information generated by the processing unit 43 in the storage unit 44.

(S8: Formation of new MPR image data)
The MPR processing unit 433a forms new MPR image data. This MPR image data may be based on the volume data formed in step 3, or may be based on the volume data obtained by newly collecting detection data, generating projection data, and forming volume data. Good.

(S9: Affine transformation)
The conversion processing unit 434 performs affine transformation based on the magnification information or affine transformation information stored in the storage unit 44 in Step 7 on the new MPR image data formed in Step 8.

  This process will be described more specifically. When the magnification information is stored in step 7, the conversion processing unit 434 performs affine transformation for enlarging or reducing at the magnification indicated in the magnification information on the new MPR image data. This affine transformation only needs to have at least the same magnification, and the rotational movement amount, the parallel movement amount, and the reverse direction are arbitrary. This affine transformation is determined by the transformation processing unit 434 based on the magnification information (and other conditions). At this time, MPR image data to be subjected to affine transformation can be analyzed, and affine transformation can be determined based on the analysis result. As an example of this analysis processing, the drawing position and / or drawing direction of the subject is specified, the parallel movement amount is obtained based on the drawing position, and the rotational movement amount is obtained based on the drawing direction. Then, the affine transformation is determined based on the parallel movement amount and the rotational movement amount and the stored magnification information.

  When the affine transformation information is stored in step 7, the transformation processing unit 434 performs affine transformation based on the affine transformation information (that is, the affine transformation set in step 6) on the new MPR image data.

(S10: Display of a new MPR image)
The display control unit 411 causes the display unit 45 to display an MPR image based on the new MPR image data that has been subjected to the affine transformation in step 9. At this time, the display control unit 411 can display a new MPR image based on the new MPR image data with the same pixel size as the MPR image displayed in Step 5. In this way, by displaying the MPR images before and after the affine transformation with the same pixel size, it is possible to prevent the size of the drawn object from being mistaken. For example, it is possible to prevent mistaking the length of the puncture needle drawn on the MPR image in the puncture operation.

(S11: Inspection finished?)
When an instruction to end the inspection is given at this stage (S11: YES), the processing of this operation example is completed. On the other hand, when the inspection is continued (S11: NO), steps 8 to 10 are performed again. Steps 8 to 10 are repeated until an instruction to end the inspection is given in step 11.

  Note that the affine transformation can be changed at any stage while the steps 8 to 10 are repeated. In that case, Steps 6 to 7 are executed again, new magnification information or affine transformation information is stored in the storage unit 44, and the processing of Steps 8 to 10 is executed based on the new magnification information or affine transformation information. .

[Action / Effect]
The operation and effect of the X-ray CT apparatus 1 according to this embodiment will be described.

  The X-ray CT apparatus 1 includes a bed apparatus 30, a collection unit 100, a volume data forming unit 432 a, an MPR processing unit 433 a, a conversion processing unit 434, a display unit 45, and a display control unit 411. The collection unit 100 collects data by scanning the subject E placed on the bed apparatus 30 with X-rays. The volume data forming unit 432a forms volume data based on the data collected by the collecting unit 100. The MPR processing unit 433a performs MPR processing on the volume data formed by the volume data forming unit 432a to form MPR image data of a predetermined cross section. The conversion processing unit 434 performs affine transformation on the MPR image data formed by the MPR processing unit 433a. The display control unit 411 causes the display unit 45 to display an MPR image based on the MPR image data obtained by the affine transformation performed by the conversion processing unit 434.

  According to such an X-ray CT apparatus 1, affine transformation can be performed on MPR image data. Therefore, it is possible to facilitate the work by automatically changing the drawing mode of the subject in the MPR image.

  The X-ray CT apparatus 1 also has a storage unit 44 that stores magnification information indicating the magnification in affine transformation. Further, when new MPR image data is formed by the MPR processing unit 433a, the conversion processing unit 434 performs affine transformation for enlarging or reducing at a magnification indicated by the magnification information stored in the storage unit 44 as a new MPR image. Apply to data. Thereby, the newly formed MPR image data can be subjected to affine transformation at the same magnification as in the past, so that it is possible to automatically obtain an MPR image in which the subject E is drawn at the same magnification. is there. Therefore, it is possible to facilitate the work.

  Further, when the storage unit 44 stores affine transformation information, the conversion processing unit 434 can be configured to perform affine transformation based on the stored affine transformation information on new MPR image data. As a result, the newly formed MPR image data can be subjected to the same affine transformation as in the past. Therefore, an MPR image in which the subject E is drawn at the same position in the frame in the same direction and the same magnification is automatically set. It is possible to obtain. Therefore, the work can be facilitated.

<Second Embodiment>
In this embodiment, an example in which affine transformation corresponding to the patient's posture is performed on the MPR image data will be described. A configuration example of the X-ray CT apparatus according to this embodiment is shown in FIG. The overall configuration of the X-ray CT apparatus is the same as that of the first embodiment, and FIG. 1 will be referred to as appropriate. Moreover, the same code | symbol is attached | subjected to the component similar to 1st Embodiment. Furthermore, the configuration and operation of the first embodiment and the configuration and operation of the second embodiment can be arbitrarily combined.

[Constitution]
An X-ray CT apparatus 200 shown in FIG. 4 has the same configuration as that of the first embodiment (see FIG. 2). The main difference in configuration with respect to the first embodiment is that a posture information input unit 50 is provided, and a conversion setting unit 434a is provided in the conversion processing unit 434. Hereinafter, these differences will be mainly described.

  The body position information input unit 50 inputs body position information indicating the body position of the subject E placed on the bed apparatus 30. The body position information input unit 50 functions as an example of an “input unit”.

  The posture information may be in any form as long as it is information that can identify the posture of the subject E. For example, the body position information may be classification information that classifies the body position of the subject E, or may be numerical information that expresses the body position numerically.

  As an example of the classification information, information (first placement direction information) indicating the placement direction of the subject E in the body axis direction of the subject E (the longitudinal direction of the top plate of the bed apparatus 30), and the subject E There is information (second placement direction information) indicating the placement direction of the subject E in the rotation direction with the body axis direction as the central axis. The latter corresponds to a rotational position (an angle with reference to a predetermined direction) centered on the body axis position in a plane (axial cross section) orthogonal to the body axis direction.

  The placement direction (first placement direction information) in the body axis direction is, for example, 2 in a placement direction in which the head is directed to the gantry device 10 side and a placement direction in which the foot portion is directed to the gantry device 10 side. Classified. In addition, the placement direction (second placement direction information) in the rotation direction centered on the body axis direction is classified into four types, for example, a supine position, a prone position, and a lateral position (rightward and leftward). When combining these, the posture of the subject E is classified into eight.

  An example of the body position information input unit 50 for inputting classification information will be described. First, the display control unit 411 causes the display unit 45 to display a screen that presents posture options based on the classification information. Each option is presented as a GUI such as an icon or a button indicating the body position. It is also possible to present options in a pull-down menu format. The user designates one of the presented options corresponding to the posture of the subject E by the operation unit 46. The control unit 41 recognizes the designated posture based on a signal input from the operation unit 46 in response to the designation operation. As another example, hardware keys (buttons, etc.) corresponding to body position options can be provided. In these examples, the body position information input unit 50 includes a display unit 45 and an operation unit 46. In FIG. 4, the posture information input unit 50 is described separately from the display unit 45 and the operation unit 46. In these examples, the posture information input unit 50 and the (display unit 45 and) operation unit 46 are integrated. Is.

  Instead of manually selecting the body position as in these examples, it is possible to provide a detection unit that detects the body position of the subject E placed on the bed apparatus 30. This detection part is comprised including the imaging | photography part which image | photographs the subject E mounted in the bed apparatus 30, for example, and the specific | specification part which analyzes the picked-up image and pinpoints a posture. The photographing unit may be a digital camera or a digital video camera, or may be the collection unit 100. The specifying unit extracts a characteristic part of the subject E (part whose drawing form changes according to the body position) from the photographed image obtained by the photographing part, and specifies the posture based on the drawing form of the characteristic part. The specific unit may perform this processing with reference to the characteristic parts (nose, navel, elbow, knee, toe, etc.) on the body surface of the subject E, or the characteristic parts in the body (organ shape, organ arrangement) Etc.), this processing may be performed. In this process, a known image processing technique such as pattern matching is used.

  Numerical information will be described. The numerical information is used, for example, to express information (second placement direction information) indicating the placement direction of the subject E in the axial section. A predetermined reference direction is set in advance in the axial section. This reference direction is, for example, x in a three-dimensional orthogonal coordinate system (x, y, z) (z direction corresponds to the body axis direction) set in a three-dimensional region (volume data formation region) to be scanned. The coordinate axis direction or the y coordinate axis direction is used. In addition, the definition direction of the angle is a clockwise direction or a counterclockwise direction with respect to the reference direction. Further, the definition interval (resolution) of the angle is arbitrary.

  An example of the body position information input unit 50 for inputting numerical information will be described. First, the display control unit 411 displays a screen for inputting numerical information on the display unit 45. The user inputs a numerical value indicating the posture using the operation unit 46. Alternatively, a predetermined image such as a schematic diagram of the subject may be displayed on the screen, the image may be rotated using the operation unit 46, and numerical information may be acquired from the rotation position. In these examples, the body position information input unit 50 includes a display unit 45 and an operation unit 46. Further, similarly to the case of the classification information, it is possible to automatically enter numerical information by providing a detection unit and a specific unit.

  Next, the conversion processing unit 434 of this embodiment will be described. As described above, the conversion processing unit 434 is provided with the conversion setting unit 434a. The conversion setting unit 434a obtains affine transformation including image inversion or rotational movement according to the body position information input by the body position information input unit 50. This process will be described.

  Note that the MPR processing unit 433a forms the MPR image data so that the direction of the subject E is always the same as in the conventional case. For example, the image data of an orthogonal three-axis image has the following form: the axial image data is formed so that the ventral side is positioned on the upper side of the frame and the back side is positioned on the lower side; the sagittal image data is formed on the left side of the frame. The front of the subject is formed so that the back is located on the right side; the coronal image data is formed so that the front of the subject is located on the front side of the frame and the back is located on the back side. Similarly, it is assumed that the oblique image data is formed so that the subject E faces in the direction in accordance with the same rule as the conventional one.

  The direction of MPR image data according to these conventional rules will be referred to as a “reference direction”. It is possible to associate the reference orientation with the posture. That is, it is possible to set in advance a reference body position (reference body position) on which neither image reversal nor rotational movement is performed. As a specific example, a setting direction in which the head is directed to the gantry device 10 side is set as a reference position in the mounting direction in the body axis direction, and a supine position is set as a reference direction in the mounting direction in the axial section. it can. When a posture other than the reference posture is applied, the necessity or content of image reversal or rotational movement can be determined based on the difference between the reference posture and the actual posture (described later).

  FIG. 5 shows a display mode of the orthogonal three-axis image when the reference posture is applied. This display screen presents an axial image in the upper center, a sagittal image in the upper right, and an image in the upper left. An arbitrary MPR image is displayed in the lower center, and GUIs are provided on the lower right side and the left side. The axial image in the reference body position is displayed such that the abdomen is positioned above the frame and the dorsal side is positioned below. The sagittal image in the reference body position is displayed such that the front of the subject is positioned on the left side of the frame and the back is positioned on the right side. That is, this sagittal image is displayed as an image of a sagittal section viewed from the left side of the subject. In addition, the coronal image in the reference body position is displayed such that the front side of the subject is positioned on the front side of the frame and the back side is positioned on the back side. That is, this coronal image is displayed as an image of a coronal section viewed from the front of the subject.

  The conversion setting unit 434 a receives the posture information input by the posture information input unit 50 via the control unit 41. The conversion setting unit 434a determines whether or not image reversal is necessary and whether or not rotational movement is necessary based on the posture indicated by the posture information and a preset reference orientation. When performing the image reversal process or the rotational movement, the conversion setting unit 434a determines the content of the image reversal or the rotational movement and obtains the affine transformation based on the displacement of the orientation indicated by the body position information with respect to the reference direction.

  As an example of the case where classification information is used as the body position information, the X-ray CT apparatus 200 includes each body position classification, conversion contents (contents of image inversion or rotational movement), and types of cross sections (axial, sagittal, coronal, etc.). Is stored in advance (for example, table information). The table information is stored in, for example, the storage unit 44, and is read out by the control unit 41 and sent to the conversion setting unit 434a before starting the processing. Further, when a storage unit is provided in the conversion setting unit 434a, table information is stored in this storage unit.

  The conversion setting unit 434a refers to the table information for the conversion contents corresponding to the posture shown in the posture information input by the posture information input unit 50 and the cross-sectional type (which is determined in advance) of the displayed image. Identify. Furthermore, the conversion setting unit 434a sets affine conversion based on the specified conversion content. Here, when the parallel movement and the magnification are set separately, the affine transformation is set in consideration of these values.

  An example of table information will be described. First, regarding the posture in the body axis direction, when this is a reference orientation, that is, when the head is disposed on the gantry device 10 side, neither image reversal nor rotational movement is performed for each section type. On the other hand, when the foot portion is arranged on the gantry device 10 side, the image is inverted in the horizontal direction of the frame for the axial section, and the image is inverted in the vertical direction of the frame for the sagittal section and the coronal section (or the image is also inverted). No rotational movement).

  Next, regarding the body position in the rotational direction in the plane (axial cross section) orthogonal to the body axis direction, when this is the reference body position, that is, the supine position, neither image reversal nor rotational movement is performed for each cross-sectional type. In the prone position, image reversal in the vertical direction of the frame is performed for the axial cross section, image reversal in the horizontal direction of the frame is performed for the sagittal cross section, and image reversal and rotational movement are not performed for the coronal cross section. In the lateral position (rightward or leftward), the axial section is rotated 90 degrees according to the direction of the subject, and the sagittal and coronal sections are neither reversed nor rotated.

  When the body position information (classification information) includes both the body position in the body axis direction and the body position in the rotational direction in the axial section, the conversion setting unit 434a combines the two conversion contents corresponding to the body positions in these two directions. Affine transformation can be set. For example, when the foot is disposed on the gantry device 10 side and is in the prone position, the axial image data is inverted both in the left-right direction and in the up-down direction. Moreover, you may make it apply the conversion content corresponding to the posture in either direction with priority. For example, when priority is given to the posture in the rotational direction within the axial cross section, when the foot is disposed on the gantry device 10 side and in the prone position, the axial image data is inverted only in the vertical direction. .

  The above table information is only an example. Further, the contents of the table information may be arbitrarily changed. In particular, it is possible to arbitrarily specify a cross section that is a target of image reversal and the like and a cross section that is not a target (including other conditions).

  When the posture in the rotational direction in the axial section is expressed as numerical information, the image is rotationally moved in the rotational direction based on the angle formed by the direction indicated by the numerical information and the reference direction. The rotation direction at this time can be determined in the same manner as in the case of the lateral position in the classification information.

[Operation]
The operation of the X-ray CT apparatus 200 according to this embodiment will be described. An operation example of the X-ray CT apparatus 200 is shown in FIG.

(S21: Position information input)
First, the subject E is placed on the top plate of the bed apparatus 30 and inserted into the opening of the gantry apparatus 10. The posture information input unit 50 inputs the posture information indicating the posture of the subject E to the control unit 41. The control unit 41 sends this body position information to the conversion setting unit 434a.

(S22: Affine transformation setting)
The conversion setting unit 434a obtains the contents of image reversal or rotational movement (conversion contents) for each cross-sectional type based on the posture shown in the posture information and the table information. Furthermore, the conversion setting unit 434a sets an affine transformation for each cross-sectional type based on the obtained conversion content (and translation and / or magnification). The process in this step may be executed at an arbitrary timing until affine transformation is performed (that is, from step 21 to step 27).

(S23: Collection of detection data)
When a predetermined scan start operation is performed, the control unit 41 sends a control signal to the scan control unit 42. Upon receiving this control signal, the scan control unit 42 controls the high voltage generation unit 14, the gantry drive unit 15, and the aperture drive unit 17 to scan the subject E with X-rays. The X-ray detection unit 12 detects X-rays that have passed through the subject E. The data collection unit 18 collects detection data sequentially generated from the X-ray detector 12 along with the scan. The data collection unit 18 sends the collected detection data to the preprocessing unit 431.

(S24: Generation of projection data)
The preprocessing unit 431 performs predetermined preprocessing on the detection data from the data collection unit 18 to generate projection data.

(S25: Formation of volume data)
The reconstruction processing unit 432 performs reconstruction processing on the projection data generated by the preprocessing unit 431 to form a plurality of tomographic image data. Further, the volume data forming unit 432a forms volume data based on these tomographic image data.

(S26: Formation of MPR image data)
The MPR processing unit 433a forms MPR image data based on the volume data formed by the volume data forming unit 432a. This MPR image data is assumed to be image data of an orthogonal three-axis image. That is, axial image data, sagittal image data, and coronal image data are formed from one volume data.

(S27: Affine transformation)
The conversion processing unit 434 converts each of the axial image data, the sagittal image data, and the coronal image data formed in step 26 by using the affine transformation set in step 22.

(S28: MPR image display)
The display control unit 411 displays the axial image, the sagittal image, and the coronal image on the display unit 45 based on the axial image data, the sagittal image data, and the coronal image data that have been subjected to the affine transformation in step 27.

(S29: Inspection finished?)
When an instruction to end the inspection is given at this stage (S29: YES), the processing of this operation example is completed. On the other hand, when the inspection is continued (S29: NO), steps 23 to 28 are performed again. Steps 23 to 28 are repeated until an instruction to end the inspection is given in step 29.

  In addition, when the posture of the subject is changed at an arbitrary stage while repeating Steps 23 to 28, a new affine transformation is set based on the new posture. Accordingly, the direction in which the MPR image is displayed is changed.

[Display example]
An image display mode by the above operation will be described. FIG. 7 shows a display example of the MPR image when the table information is applied and the body position is prone. Here, it compares with the display mode corresponding to the reference | standard direction shown in FIG. The axial image (upper center image) shown in FIG. 7 is obtained by inverting the axial image shown in FIG. 5 in the vertical direction. Further, the sagittal image (upper right image) shown in FIG. 7 is obtained by inverting the sagittal image shown in FIG. 5 in the left-right direction. The coronal image has the same display mode in both drawings. These inversion conditions correspond to the prone position in the table information. According to this embodiment, the display direction of the MPR image is thus changed according to the posture. In this embodiment as well, in the same way as in the first embodiment, it is possible to prevent a mistake in the size of an object to be drawn by combining the pixel sizes of a plurality of displayed MPR images.

[Action / Effect]
The operation and effect of the X-ray CT apparatus 200 according to this embodiment will be described.

  The X-ray CT apparatus 200 includes a couch device 30, a collection unit 100, a volume data formation unit 432a, an MPR processing unit 433a, a conversion processing unit 434, a display unit 45, and a display control unit 411. The collection unit 100 collects data by scanning the subject E placed on the bed apparatus 30 with X-rays. The volume data forming unit 432a forms volume data based on the data collected by the collecting unit 100. The MPR processing unit 433a performs MPR processing on the volume data formed by the volume data forming unit 432a to form MPR image data of a predetermined cross section. The conversion processing unit 434 performs affine transformation on the MPR image data formed by the MPR processing unit 433a. The display control unit 411 causes the display unit 45 to display an MPR image based on the MPR image data obtained by the affine transformation performed by the conversion processing unit 434.

  According to such an X-ray CT apparatus 200, affine transformation can be performed on MPR image data. Therefore, it is possible to facilitate the work by automatically changing the drawing mode of the subject E in the MPR image.

  Further, the X-ray CT apparatus 200 includes a body position information input unit 50 (input unit) that inputs body position information indicating the body position of the subject E placed on the bed apparatus 30. Furthermore, the conversion processing unit 434 includes a conversion setting unit 434a that calculates an affine transformation including conversion contents (image inversion or rotational movement) according to the posture information input by the posture information input unit 50. The conversion processing unit 434 performs affine transformation obtained by the conversion setting unit 434a on the MPR image data.

  According to such an X-ray CT apparatus 200, the orientation of the MPR image can be changed according to the posture of the subject E. Therefore, it is possible to facilitate the work by automatically changing the drawing mode of the subject E in the MPR image. Further, since the deviation between the orientation of the subject E that is actually visually recognized (that is, the orientation of the subject E in the real space) and the orientation of the displayed MPR image can be eliminated, the work can be performed smoothly. Contribute to successful execution.

  In addition, the MPR processing unit 433a forms a plurality of MPR image data having different cross sections based on the volume data. In this case, the conversion processing unit 434 can selectively perform the affine transformation obtained by the conversion setting unit 434a on the plurality of MPR image data formed by the MPR processing unit 433a. In the above example, axial image data, sagittal image data, and coronal image data are formed, and affine transformation is performed on arbitrary image data among these.

  In addition, it is possible to arbitrarily specify MPR image data to be subjected to affine transformation. This designation operation is performed using the operation unit 46. Furthermore, it is possible to arbitrarily change the contents of affine transformation applied to the MPR image data.

  According to such an X-ray CT apparatus 200, desired affine transformation can be performed on desired MPR image data, so that an MPR image can be displayed in an orientation according to the user's needs.

  The configuration and operation of the X-ray CT apparatus 200 of the first embodiment can be combined with the configuration and operation of the X-ray CT apparatus 200 as described above. For example, in the X-ray CT apparatus 200 of this embodiment, the magnification information indicating the magnification in the affine transformation is stored in the storage unit 44. When new MPR image data is formed by the MPR processing unit 433a, the conversion setting unit 434a converts the posture indicated by the posture information input by the posture information input unit 50 and the magnification information stored in the storage unit 44. Based on this, set the affine transformation. The conversion processing unit 434 performs this affine transformation on new MPR image data. As another combination example, the storage unit 44 stores affine transformation information including the magnification information. This affine transformation information may or may not include image inversion and rotational movement information. The conversion setting unit 434 a sets a new affine transformation based on the posture indicated by the posture information input by the posture information input unit 50 and the affine transformation information stored in the storage unit 44. As the parameters for image inversion or rotational movement in this new affine transformation, for example, the parameters included in the affine transformation information or the parameters corresponding to the posture (parameters shown in the table information etc.) are applied for the reference posture. In this case, parameters corresponding to the posture are applied. The conversion processing unit 434 performs this new affine transformation on the new MPR image data.

  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 1,200 X-ray CT apparatus 10 Base apparatus 11 X-ray generation part 12 X-ray detection part 13 Rotating body 14 High voltage generation part 15 Base drive part 16 X-ray aperture part 17 Aperture drive part 18 Data collection part 30 Bed apparatus 40 Console Device 41 Control unit 411 Display control unit 42 Scan control unit 43 Processing unit 431 Preprocessing unit 432 Reconstruction processing unit 432a Volume data forming unit 433 Rendering processing unit 433a MPR processing unit 434 Conversion processing unit 434a Conversion setting unit 44 Storage unit 45 Display Unit 46 Operation unit 50 Posture information input unit 100 Collection unit

Claims (9)

A collection unit that collects data by scanning an object placed on the bed apparatus with X-rays;
A volume data forming unit that forms volume data based on the collected data;
An MPR processing unit that performs MPR processing on the formed volume data to form MPR image data of a predetermined section;
An X-ray CT apparatus comprising: a conversion processing unit that performs affine transformation on the formed MPR image data; and a display control unit that displays an MPR image based on the MPR image data obtained by the affine transformation on a display unit. A storage unit for storing magnification information indicating a magnification in the affine transformation;
When new MPR image data is formed by the MPR processing unit, the conversion processing unit performs affine transformation for enlarging or reducing at the magnification indicated in the stored magnification information on the new MPR image data. The X-ray CT apparatus according to claim 1. The storage unit includes the magnification information, stores affine transformation information indicating the affine transformation,
The X-ray CT apparatus according to claim 2, wherein the conversion processing unit performs affine transformation based on the stored affine transformation information on the new MPR image data. An input unit for inputting posture information indicating the posture of the subject placed on the bed apparatus;
The conversion processing unit includes a conversion setting unit for obtaining an affine transformation including an image inversion or a rotational movement according to the input body posture information, and performs the obtained affine transformation on the MPR image data. The X-ray CT apparatus as described in any one of Claims 1-3. The MPR processing unit forms a plurality of MPR image data having different cross sections based on the volume data,
The X-ray CT apparatus according to claim 4, wherein the conversion processing unit selectively performs affine transformation obtained by the conversion setting unit on the plurality of MPR image data. An operation unit for designating one or more of the plurality of MPR image data;
The X-ray CT apparatus according to claim 5, wherein the conversion processing unit performs affine transformation obtained by the conversion setting unit on each designated MPR image data.   The X-ray CT apparatus according to claim 5, wherein the plurality of MPR image data includes one or more of axial image data, sagittal image data, and coronal image data.   The body position information includes first placement direction information indicating the placement direction of the subject in the body axis direction of the subject and / or the subject in a rotation direction with the body axis direction as a central axis. The X-ray CT apparatus according to any one of claims 4 to 7, further comprising second placement direction information indicating a placement direction.   The display control unit is configured to display the MPR image based on the MPR image data before the affine transformation and the MPR image based on the MPR image data after the affine transformation with the same pixel size. The X-ray CT apparatus according to any one of claims 1 to 8, wherein the X-ray CT apparatus is displayed.

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