JP6777407B2 - Helical CT device, medical image processing method, and medical image processing program - Google Patents

Description

The present disclosure relates to a helical CT apparatus.

Conventionally, a multi-slice CT apparatus having a multi-row X-ray detector and generating a plurality of slice images each time the multi-row X-ray detector makes one rotation by X-rays emitted as a cone beam is known. (See Patent Document 1).

Further, in the case of acquiring 4D data (x, y, z coordinate data and time data) on the time series of the subject, the conventional CT apparatus executes a routine (4D imaging routine) for imaging the 4D data. To do. In the 4D imaging routine, the conventional CT device acquires the 4D data of the subject a plurality of times by acquiring the 3D data (x, y, z coordinate data) imaged at the same position in the body axis direction of the subject. get.

U.S. Pat. No. 6,917,663

In the multi-slice CT apparatus of Patent Document 1, when the subject is longer in the body axis direction than the width of the X-ray detector, it is necessary to move and stop the position of the X-ray detector many times in order to obtain 4D data. Therefore, it is difficult to acquire a wide range of 4D data.

The present disclosure has been made in view of the above circumstances, and provides a helical CT apparatus capable of easily acquiring a wide range of 4D data, a medical image processing method, and a medical image processing program.

Helical CT apparatus of the present disclosure, have a detector a plurality of rows, a helical CT apparatus which performs helical scan, the first time, to scan a portion of the subject in the first position in the body axis direction , A part of the subject is scanned at the first position in the body axis direction at the second time with the first detector for acquiring the first scan information, and the second scan information is acquired. It includes a second detector and a processor that acquires time series information at the first position in the body axis direction based on the first scan information and the second scan information.

The medical image processing method of the present disclosure is a medical image processing method in a helical CT apparatus that performs a helical scan, in which a part of a subject is scanned at a first position in the body axis direction at a first time, and the first The scan information of 1 is acquired, a part of the subject is scanned at the first position in the body axis direction at the second time, the second scan information is acquired, and the first scan information is obtained. And the second scan information, the time series information at the first position in the body axis direction is acquired.

The medical image processing program of the present disclosure is a program for causing a computer to execute the above-mentioned medical image processing method.

According to the present disclosure, 4D data of the entire subject can be easily obtained, which contributes to diagnosis.

Block diagram showing a schematic configuration example of the CT apparatus according to the first embodiment The figure explaining the operation example of imaging a subject with a CT apparatus. Schematic diagram for explaining an example of a CT image creation method Explanatory diagram showing an example of the process of generating a synogram Explanatory drawing showing an example of the process of reconstructing the original image from the synogram Schematic diagram illustrating a first example of an X-ray detection operation by an X-ray detector Schematic diagram illustrating a second example of X-ray detection operation by an X-ray detector Schematic diagram illustrating a third example of X-ray detection operation by an X-ray detector Schematic diagram illustrating an example of collecting time-series information Schematic diagram showing a composite example of a functional image and a morphological image Schematic diagram illustrating an example of generating a morphological image A flowchart showing an example of a procedure for generating slice data in a plurality of phases at the same position in the body axis direction. Schematic diagram showing slice data obtained in multiple phases

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

(First Embodiment)
FIG. 1 is a block diagram showing a schematic configuration of a CT (Computed Tomography) apparatus 5 according to the first embodiment. The CT device 5 is, for example, a multi-slice helical CT device.

The CT apparatus 5 takes an X-ray tomographic image and performs helical rotation in which a multi-row X-ray detector is rotated together with an X-ray tube while moving a subject placed on a bed in the body axis direction (Z direction). The X-ray detector detects the X-rays emitted from the X-ray tube toward the subject during helical rotation, and makes the subject 360 ° (or 180 ° + fan angle) or cone angle (cone angle). )) Is imaged from various projection directions in the range of), and a plurality of projected images (sinograms) are simultaneously obtained.

The CT device 5 includes a gantry 40, a console 30, and a high voltage generator 43 that generates a high voltage.

The gantry 40 scans (images) the region of interest (ROI: Region of Interest) of the subject M using X-rays, and obtains a scan result (imaging result). The scan is performed by X-ray irradiation and X-ray detection. The gantry 40 includes an X-ray tube 41 and a multi-row X-ray detector 42. Multi-column is an example of multiple columns.

The X-ray tube 41 irradiates the subject M with X-rays. The X-ray tube 41 is supplied with a necessary power supply voltage such as a tube current and a tube voltage from the high voltage generator 43. The X-ray tube 41 irradiates the subject M with a fan beam-shaped or cone-beam-shaped X-ray bundle by attaching a collimator or a slit. In this embodiment, a case of irradiating a cone beam-shaped X-ray flux is shown.

The X-ray detector 42 has a plurality of rows of detectors, detects X-rays that have passed through the subject M, obtains X-ray transmission data, and generates a synogram. The width (length in the body axis direction) of the X-ray detector 42 is, for example, 160 mm in the case of 256 rows. Synogram is an example of scan results.

The console 30 performs various processes and displays on the scan data obtained by the gantry 40. The console 30 includes a UI (User Interface) 10, a controller 20, a port 50, an image processor 60, and a display 70.

The UI 10 may include a touch panel, a pointing device, a keyboard, or a microphone. The UI 10 accepts an arbitrary input operation from the user of the CT device 5. The user may include a doctor, a radiologist, or other Paramedic Staff.

The controller 20 controls the entire CT device, and is configured by, for example, mounting a device control calculation method on dedicated hardware or a personal computer. By operating the UI 10 connected to the controller 20, the scan result by the gantry 40 can be collected and displayed. The controller 20 may include a CPU (Central Processing Unit) and an MPU (Micro Processing Unit).

The port 50 acquires various information and various data from the outside of the console 30. The port 50 may include a communication port for communicating via a wired or wireless communication line, and an external device connection port to which an external device (for example, a gantry 40) is connected. Port 50 collects the scan data acquired by the gantry 40.

The image processor 60 performs various image processing on the scan data from the port 50. The image processor 60 generates a tomographic image (slice data) of the region of interest of the subject M based on the scan data. Areas of interest may include areas of lesions or tissues (eg, blood vessels, organs). The image processor 60 may include a CPU, a DSP (Digital Signal Processor), or a GPU (Graphical Processing Unit).

The display 70 may include an LCD (Liquid Crystal Display) and displays various images and various information. The display 70 displays a tomographic image generated by the image processor 60.

For example, the controller 20 controls the X-ray tube 41 and the high voltage generator 43 to generate X-rays. The X-rays that have passed through the subject M are converted into electrical signals by the X-ray detector 42. The converted electrical signal is AD-converted by an AD converter (not shown) to obtain X-ray transmission data (scan data). The image processor 60 performs image processing (for example, sensitivity correction, distortion correction) on the X-ray transmission data. The display 70 displays the image-processed data.

The memory 80 includes various ROM (Read Only Memory) and RAM (Random Access Memory) primary storage devices. The memory 80 may include a secondary storage device such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive).

The memory 80 stores various information, various images, and programs. The memory 80 may include an image generated by the image processor 60 and setting information set by the controller 20. The image here includes, for example, slice data (slice image), volume data, morphological image (anatomical structure image), functional image (functional image), synogram, etc., which will be described later.

FIG. 2 is a schematic diagram illustrating an operation of imaging the subject M with the CT device 5. In the CT apparatus 5, a multi-row X-ray detector 42 arranged in the body axis direction, together with the X-ray tube 41, is used to image a target part (subject) of the human body from an arbitrary projection direction of 360 °. Rotate.

Since the X-ray detector 42 detects the X-rays that have passed through the subject M, the rotation of the X-ray detector 42 and the X-ray tube 41 can be rotated by 180 ° (+ fan angle or cone angle) instead of 360 °. Good. In the present embodiment, the rotation required to acquire the synogram required for image reconstruction is counted as one rotation. The X-ray detector 42 detects X-rays emitted in a cone beam shape from the X-ray tube 41, obtains X-ray transmission data, and generates a synogram every time it makes one rotation. Synograms are generated for each detector in the X-ray detector 42, and the same number as the number of detectors is generated.

The image processor 60 acquires a synogram from the X-ray detector 42. The image processor 60 performs image reconstruction to generate a cross section (original image) of the original subject M based on the synogram, and generates slice data (see Reference Patent Documents 1 and 2).
(Reference Patent Document 1: Japanese Patent No. 4083719)
(Reference Patent Document 2: US Pat. No. 7,754,027)

Image reconstruction is also referred to as Back Projection. The image reconstruction method includes a filter-corrected back projection FBP (Filtered Back Projection) and an iterative reconstruction (Iterative Reconstruction).

Further, the image processor 60 may generate volume data by stacking slice data obtained for each detector. The slice data corresponds to a tomographic image. Slice data and volume data are treated as CT images.

FIG. 3 is a schematic view for explaining a method of creating a CT image. FIG. 4 is an explanatory diagram showing a process of generating a synogram from the subject M. FIG. 5 is an explanatory diagram showing a process of reconstructing an original image from a synogram. The details of the method for creating a CT image are described in, for example, Reference Patent Document 1, and will be briefly described here.

The X-ray transmission data by the X-ray detector 42 is one-dimensional projection data from one projection angle. In FIG. 3, the one-dimensional projection data is represented by Pθ1 (t), Pθ2 (t), .... As shown in FIG. 3, the X-ray detector 42 acquires one-dimensional projection data for one rotation by acquiring X-ray transmission data at a plurality of projection angles around the subject M, and these Two-dimensional projection data is generated by synthesizing one-dimensional data.

As shown in FIG. 4, the X-ray detector 42 projects (maps) two-dimensional projection data from Cartesian coordinates (x, y) to rotating coordinates (r, θ) to generate a synogram. This projection is performed by the Radon transform and the synogram is input to the console 30. In FIG. 4, f (x, y) represents a pixel value (pixel value) in Cartesian coordinates (x, y), and p (r, θ) represents a pixel value in rotating coordinates (r, θ).

The image processor 60 acquires the synogram from the gantry 40 and performs a filter process for suppressing blurring (blurring) of the image due to a numerical error. After the filtering process, the image processor 60 reconstructs the image with respect to the synogram to obtain the original image. In image reconstruction, as shown in FIG. 5, the image processor 60 projects each line of the synogram onto the reconstructed image (slice data) according to the projection angle, and adds the images. The image processor 60 generates slice data (original image) at a predetermined position in the body axis direction by image reconstruction.

FIG. 6 is a schematic diagram illustrating a first example of an X-ray detection operation by the X-ray detector 42. In FIG. 6, the X-ray detector 42 is divided into two groups along the body axis direction. In FIG. 6, each group has four rows of detectors, but each group may have one row or a plurality of other rows. The X-ray tube 41 irradiates the subject M with X-rays 41r in a cone beam shape.

When the CT device 5 rotates helically, there are places where X-rays are detected at the same position in the body axis direction in the first rotation and the second irradiation. The position in the body axis direction is the position in the Z direction and is represented by the Z coordinate. In FIG. 6, the X-ray detector 42 detects X-rays overlapping in the first rotation and the second rotation in the range e. The X-ray detector 42 detects X-rays overlapping in the second rotation and the third rotation in the range f. Further, the X-ray detector 42 detects X-rays overlapping at the first rotation, the second rotation, and the third rotation at the portion where the range e and the range f overlap.

Therefore, in FIG. 6, a plurality of synograms can be obtained at the positions included in the ranges e and f. The CT apparatus 5 obtains the plurality of synograms with a time difference and generates slice data at a plurality of times (phases). It is not necessary to scan the same position in each phase at the same projection angle.

FIG. 7 is a schematic diagram illustrating a second example of the X-ray detection operation by the X-ray detector 42. In FIG. 7, the X-ray detector 42 is composed of 256 rows, and may be divided into four groups in the Z direction for every 64 rows. Further, the X-ray detector 42 moves the position in the body axis direction by one group, that is, by 64 columns for each helical rotation (one rotation helical scan) to detect X-rays. In FIG. 7, 64 columns in one group are shown by two blocks.

That is, in FIG. 7, X-rays for four rotations are detected at the same position in the body axis direction. Therefore, the X-ray detector 42 generates four synograms having different time series at each position in the body axis direction. Further, the image processor 60 generates 4-phase slice data SG based on the four synograms. Such synograms over multiple phases and slices of the result of back projection are called time series information.

The number of rows of the X-ray detector 42 is not limited to 256, and may be any number such as 128 rows and 512 rows. Further, the number of divisions of the group is not limited to 4 divisions, and may be any number of divisions such as 2 divisions and 8 divisions. Further, it is sufficient that there is simply an overlapping portion instead of moving 64 rows for each helical rotation.

FIG. 8 is a schematic diagram illustrating a third example of the X-ray detection operation by the X-ray detector 42. Also in FIG. 8, the X-ray detector 42 is composed of 256 rows, and each 64 rows is divided into four in the Z direction. Further, in FIG. 7, it is illustrated that the X-ray detector 42 moves 64 rows in the Z direction for each helical rotation, but it does not move exactly 64 rows, but 64 rows or more and less than 65 rows, etc. It may be a movement of.

Here, the detector width described later is the length of one detector in the X-ray detector 42 in the Z direction. The slice interval is the difference in position in the Z direction from which adjacent slice data are obtained. The slice thickness is the thickness of the fault in the Z direction indicated by one slice data. The slice thickness and slice interval may not match due to reasons such as interpolation and detector accuracy.

Even if the slice interval does not match an integral multiple of the detector width, different detectors may scan at different times so that they include the same position in the body axis direction. The image processor 60 acquires time series information based on the results of a plurality of scans by different detectors.

The time-series information is information indicating a plurality of slice data in a plurality of phases at the same position in the body axis direction, a synogram that is a source of the plurality of slice data, and the like. By analyzing the time series information, the change over time of the tissue can be known.

In FIG. 8, one group is shown by two blocks. X-ray detection by the second rotation X-ray detector 42 is started at the intermediate position of the third block (65th row to 95th row) of the X-ray detector 42 in the first rotation (see arrow i). .. In this case, the image processor 60 sets the intermediate value of the third block of the X-ray detector 42 in the first rotation as the X-ray detection value of the second block (33rd to 64th columns) in the first rotation and one rotation. An interpolated value is generated by interpolating with the X-ray detection value of the third block in the eye (cone beam interpolation). As a method for obtaining the interpolated value here, a known method is used, and is shown in, for example, Reference Non-Patent Document 1.
(Reference Non-Patent Document 1: Flohr TG, Schaller S, Steerstofer K, Bruder H, Owner BM, Schoepf UJ: “Multidentor low CT system Radiology, radio, radio, radio, image, image, image , 2005)

The image processor 60 is based on the X-ray detection value of the first block by the X-ray detector 42 of the second rotation and the interpolated value of the third block of the X-ray detector 42 of the generated first rotation. Get time series information.

The image processor 60 also obtains time series information for other blocks (for example, the 4th block to the 8th block) by using the interpolated values.

Further, the image processor 60 may include one scan result in a plurality of synograms corresponding to different times. The image processor 60 acquires the first synogram by scanning 0 ° to 180 ° + fan angle, and acquires the second synogram by scanning 90 ° to 270 ° + fan angle, whereby the detector rotates 90 °. Time-series information corresponding to the time required to do this can be acquired.

FIG. 9 is a schematic diagram illustrating the collection of time series information. In FIG. 9, the downward direction in the vertical direction represents the body axis direction (Z direction), and the right direction in the horizontal direction represents the scan time at which the scan was performed.

The X-ray detector 42 divides the synogram for one helical rotation into the number of detectors at scan times t0 to t1, t1 to t2, t2 to t3, t3 to t4, t4 to t5, t5 to t6, and t6 to t7. Just get.

The image processor 60 may generate time series information dI at the same position in the body axis direction based on a plurality of synograms. The image processor 60 may generate a plurality of slice data based on a plurality of synograms and generate time series information dI based on the plurality of slice data. The image processor 60 may generate a plurality of volume data based on a plurality of slice data and generate time series information dI based on the plurality of volume data.

In the time series information dI, the range of the scanned time is different for each position in the body axis direction. For example, the image processor 60 generates time series information dI3 based on the projection data acquired over the scan times t2 to t6. The time series information dI may be indicated by functional information.

By using the time-series information dI, the CT device 5 can derive functional information such as flow rate such as blood flow, flow velocity, and tissue movement with high accuracy.

Next, functional information and morphological information will be described.

The functional information is information indicating the activity state of the organization calculated from the time series information. The functional information is based on changes such as differences and movements of data such as multiple slice data and synograms in multiple phases.

The image processor 60 can acquire a change in the density of the contrast medium or tissue by changing the pixel value at the same coordinates. Further, the image processor 60 can acquire the movement amount, speed, and acceleration of the spatial movement of the tissue having the same pixel value. The image processor 60 simultaneously acquires, for example, the registration process, the density change at the same location of the tissue, and the movement of the tissue by these (that is, the amount of spatial movement of the tissue having the same pixel value, the speed, and the acceleration). .. As a result, the image processor 60 can acquire the object that moves while changing the density as functional information. The concentration change may include a blood vessel through which the contrast medium passes, or a concentration change accompanying contraction of the lungs. The image processor 60 may acquire the density change as difference information (for example, after correcting the movement) and convert the difference information into functional information. This functional information may include the blood flow velocity in the blood vessel through which the contrast medium passes, and the pulmonary ventilation rate calculated from the contraction of the lungs. The functional information may be displayed as a functional image FG (see FIG. 10) on the display 70.

The image processor 60 may calculate the change in blood flow velocity based on the change in the shade value (change in shade). The image processor 60 may calculate the wall pressure and wall motion state of the blood vessel based on the moving speed and acceleration of the tissue.

Further, the display 70 may be displayed as a moving image showing a change with time as a functional image FG under the control of the controller 20, or may be displayed as a still image.

The display 70 may also display the scan time (for example, t2 to t6) when displaying the functional image FG under the control of the controller 20. As a result, the user can visually recognize at which timing the time series information dI is shown. The scan time may be indicated based on any reference time. The arbitrary reference time may be the start time of injection of the contrast medium into the subject M.

In addition, the morphological information indicates the same part between slice data at the same position in the body axis direction in a plurality of phases. The same portion is a portion where the difference in pixel values between these slice data is less than a predetermined value. The morphological information may be displayed as a morphological image EG (see FIG. 10). That is, the morphological image is an image expressing a normal tissue shape.

Next, registration (alignment) between a plurality of phases will be described.

The image processor 60 may register a plurality of synograms or slice data in a plurality of phases. By registration, the CT apparatus 5 can suppress the deviation of the synogram or slice data due to the movement of the subject M.

The image processor 60 may acquire the time series information dI after registering the synogram or slice data between a plurality of phases.

The image processor 60 may calculate the amount of movement of points in the synogram or slice data based on the synogram or slice data after registration of each phase. As a result, the CT device 5 can improve the calculation accuracy of the movement amount such as blood flow and the movement speed based on the movement amount.

The image processor 60 may perform 3D registration in the state of volume data instead of synogram or slice data.

Registration is carried out by a known method, and for example, the methods of Reference Patent Documents 3 to 5 are used.
(Reference Patent Document 3: US Pat. No. 8311300)
(Reference Patent Document 4: US Patent Application Publication No. 2011/0075896)
(Reference Patent Document 5: US Patent Application Publication No. 2011/0075888)

The image processor 60 may synthesize four-phase slice data after registration to generate a morphological image in which motion artifacts (image quality deterioration due to blurring or blurring of organ margins) are suppressed (see Reference Patent Document 6). In compositing, for example, the average value of pixel values and voxel values is used.
(Reference Patent Document 6: US Patent Application Publication No. 2008/0031405)

FIG. 10 is a schematic diagram showing a composite example of the functional image FG and the morphological image EG. In FIG. 10, the image processor 60 uses the four slice data SGs as time series information to generate a functional image FG. Further, the image processor 60 registers four slice data SGs to generate a morphological image EG with improved image quality. Then, as an example, the image processor 60 synthesizes the morphological image EG as a shade and the functional image FG as a color.

The image processor 60 generates one morphological image EG as slice data for the entire imaging range of the subject M. Each pixel value of the morphological image EG may be an average value of pixel values at the same position in the body axis direction in a plurality of phases.

The image processor 60 generates various functional image FGs as slice data within the range in which slice data of a plurality of phases are acquired. The functional image FG may represent a change in the concentration of tissue or blood flow in the subject M, a movement amount, a movement speed, or the like.

Regarding the composition of the functional image FG and the morphological image EG, the image processor 60 performs drawing processing (color lookup) such as color painting on a portion where the value indicated by the functional information is equal to or higher than a predetermined value to obtain the combined image. It may be generated.

As a result, the CT device 5 can easily identify the changed portion from the slice data in the other phase. In FIG. 10, the portion where the density change between the slice data of the plurality of phases is equal to or more than a predetermined value is represented in red (dot display in the figure).

Further, the image processor 60 may generate a composite image MG by superimposing the functional image FG and the morphological image EG. Further, the image processor 60 may create volume data indicating the function and volume data indicating the form by stacking the functional image FG and the form image EG.

When the image processor 60 visualizes both the morphological image EG and the functional image FG by the 3D raycast method, the image processor 60 shades using the voxel value of the morphological image EG and color looks up using the voxel value of the functional image FG. You may.

When the image processor 60 visualizes both the morphological image EG and the functional image FG by the MIP method, the image processor 60 creates a MIP image using the voxel values of the morphological image EG, and the coordinates of the voxels used to create the MIP image. The Voxel value of the functional image FG corresponding to the above may be used for color lookup to color the MIP image.

Further, the image processor 60 may generate the combined volume data by synthesizing the functional volume data and the morphological volume data.

FIG. 11 is a schematic diagram illustrating the generation of a morphological image as volume data. In FIG. 11, it is assumed that the CT apparatus 5 registers with the entire imaging range (X-ray detection range) of the subject M and generates one morphological image. The entire imaging range may include the aorta and lower extremities.

In FIG. 11, as in FIG. 9, the downward direction in the vertical direction represents the body axis direction (Z direction), and the right direction in the horizontal direction represents the scan time. The X-ray detector 42 acquires synograms for one helical rotation at scan times t0 to t1, t1 to t2, t2 to t3, t3 to t4, t4 to t5, t5 to t6, and t6 to t7, respectively.

In the first step, the image processor 60 registers slice data having overlapping positions in the Z direction among the slice data based on the scan results in each phase.

In the second step, the image processor 60 synthesizes the registered slice data. The image processor 60 can improve the image quality (S / N ratio) of the morphological image by synthesizing with the average value of the voxel values of each slice data. Further, the image processor 60 can emphasize the contrast of the morphological image by synthesizing with the maximum value of the voxel value of each slice data. In FIG. 11, the dot display represents the scan result after registration.

In the third step, the image processor 60 stacks slice data along the Z direction to generate volume data of one morphological image (for example, images at scan times t1 to t5).

FIG. 12 is a flowchart showing a procedure for generating slice data in a plurality of phases at the same position in the body axis direction. FIG. 13 is a schematic diagram showing slice data obtained in a plurality of phases. In FIG. 13, the vertical direction indicates the time (phase), and the horizontal direction indicates the body axis direction (Z direction).

First, in the controller 20, each detector of the n × m X-ray detectors 42 is D (i, j) (S1). The variable i represents the column number of the detector in the X-ray detector 42, and the variable j represents the division number. i <n, j <m, and the initial values of i and j are "0". n represents the number of rows of detectors in the divided block, and m represents the number of divisions. In FIG. 13, n = 2 and m = 4.

The image processor 60 generates slice data S (i, j, q) for each rotation of the helical scan under the control of the controller 20 (S2). The variable q indicates the helical rotation speed, corresponds to the phase, and the initial value is 0. As a result, n × m slice data at the qth rotation can be obtained.

The controller 20 advances the bed by n × detector width for each rotational helical scan (S3). As a result, the X-ray irradiation and detection positions on the subject M move. In FIG. 13, since the detector width is 1 mm, the bed moves along the Z direction by one block (2 mm).

The image processor 60 controls the slice data S (0, m-1,0), S (0, m-2,1), ..., S (0,0, m-1) under the control of the controller 20. Generates time-series information indicating changes over time (S4). Slice data S (0,3,0), S (0,2,1), ..., S (0,0,3) are slices at the same position in the Z direction (see line L1 shown in FIG. 13). It becomes data.

Similarly, the image processor 60 controls the following slice data S (1, m-1,0), S (1, m-2,1), ..., S (1,0, m) under the control of the controller 20. -1) Generates time-series information indicating changes over time (S4). Slice data S (1,3,0), S (1,2,1), ..., S (1,0,3) are slices at the same position in the Z direction (see line L2 shown in FIG. 13). It becomes data.

When n = 3 or more, the image processor 60 controls the slice data S (n-1, m-1,0), (n-1, m) by the same processing as in S4 and S5 under the control of the controller 20. -2, 1), ..., (n-1, 0, m-1), generate time-series information indicating changes over time.

In this way, the CT device 5 acquires time series information at each position in the Z direction by using the X-ray detector 42 in the n × m row, and ends this process.

(Application example of CT device)
Examples of clinical application of the CT device 5 include the following (a) to (c), and the following effects are expected. According to the CT device 5, the flow of body fluid such as blood flow can be easily obtained.

(A) CT device 5 may be used for false cavity evaluation in aortic dissection. In aortic dissection, there is a difference in blood flow between the false lumen created by the dissection and the true lumen, which is the original blood vessel. A contrast agent is injected into subject M to observe blood flow. The CT device 5 determines the blood flow based on the movement of the detected value (corresponding to the contrast density) of the scan result. The timing of contrast for observing blood flow (timing of injecting a contrast medium) is strict, and it is difficult to perform contrast at an appropriate timing. According to the CT apparatus 5, by displaying time-series information (for example, a functional image) based on the scan result, the user can easily recognize the timing of contrast enhancement, so that the contrast enhancement can be performed at an appropriate timing and the blood flow can be visually recognized. It becomes easier to do.

(B) The CT device 5 may be used for analysis of the vascular structure of the liver. The liver has three blood vessels, the portal vein, the artery, and the vein, and the vascular structure of the portal vein, the artery, the vein, and the bile duct may be evaluated. When a contrast medium is injected into the portal vein, the contrast medium flows out from the portal vein into a vein, making it difficult to evaluate the vascular structure of the portal vein. On the other hand, the CT device 5 can facilitate the evaluation of the liver by displaying time series information (for example, a functional image) based on the scan result.

(C) The CT device 5 may be used for venous blood flow evaluation. The contrast medium flows into the vein from the artery into which the contrast medium is injected. Therefore, it is difficult to recognize the imaging timing of veins. On the other hand, when the CT device 5 displays time series information (for example, a functional image) based on the scan result, the user can easily confirm the blood flow in the vein. The CT device 5 is effective for evaluating blood flow in, for example, economy syndrome.

(Effects, etc.)
In the conventional helical CT device, when the trunk fixed to the bed is moved at high speed, the X-ray detector images the subject at the same position in the body axis direction, and if the synogram overlaps, the overlap occurs. The X-ray was used to improve the image quality, and there was no idea to obtain information on the time series.

On the other hand, the CT device 5 has a plurality of rows of detectors, and includes a first detector, a second detector, and a processor. The first detector scans a part of the subject M at the first position in the body axis direction at the first time, and acquires the first scan information. The second detector scans a part of the subject M at the first position in the body axis direction at the second time, and acquires the second scan information. The processor acquires the time series information dI at the first position in the body axis direction based on the first scan information and the second scan information.

The CT device 5 is an example of a helical CT device. The first detector may be one of the detectors included in the X-ray detector 42. The second detector may be one of the other detectors included in the X-ray detector 42. The processor may be controller 20 or image processor 60. The scan information is, for example, a synogram.

As a result, the CT device 5 can image the same position in the body axis direction of the subject M while moving the subject M in the body axis direction. Therefore, the CT device 5 can acquire 4D data even when the subject is longer in the body axis direction, such as the trunk including the aorta and the lower limbs, as compared with the width of the X-ray detector 42. That is, the CT device 5 can acquire slice data or volume data of a plurality of phases in the time direction by obtaining scan results at different times at the same position in the body axis direction.

Further, in the CT apparatus 5, the conventional 4D imaging routine becomes unnecessary by performing the scan for routine inspection by making the slice interval relatively short so as to include the scan at the same position in the body axis direction in a plurality of phases. Exposure can be reduced and invasiveness can be reduced. That is, the CT device 5 does not need to be stationary at each part of the subject and repeat the operation of irradiating the X-ray to take an image, and can reduce the exposure of the part of the subject M to be imaged in duplicate. Even in this case, the CT device 5 can obtain time series information.

Further, the CT apparatus 5 can generate a scan image (normal CT image) for a normal routine inspection by reconstructing an image based on the obtained synogram, which is rational and non-invasive in terms of medical economy. is there.

Further, the processor may register the first scan information and the second scan information, and acquire the time series information based on the registered first scan information and the second scan information. ..

As a result, even if the subject M moves slightly during imaging, the image quality of the captured image can be improved by registration. In addition, the CT apparatus 5 can derive an accurate flow rate between phases by registering.

Further, the processor may generate functional information in the subject M at the first time and the second time based on the time series information dI.

As a result, the CT device 5 can display the change over time of the subject M as functional information. The function information may be a function image FG, or the function may be indicated by a method other than the image.

Further, the functional information may include information on the flow velocity of the body fluid (for example, blood) in the subject M.

As a result, the CT device 5 can provide the user with information on the flow velocity and support diagnosis based on the information on the flow velocity.

Further, the processor may generate morphological information based on the first scan information and the second scan information. The morphological information may be a morphological image EG.

As a result, the CT apparatus 5 can clearly express a normal (no notable change) tissue shape.

Further, the processor may register the first scan information and the second scan information, and generate morphological information based on the registered first scan information and the second scan information.

As a result, the CT apparatus 5 can improve the image quality of the morphological image by registration even if the subject M moves a little during imaging.

Further, the processor may generate morphological information based on the combination of the first scan information and the second scan information.

As a result, the CT apparatus 5 can synthesize a plurality of slice data after registration and suppress the influence of unintended motion artifacts.

The processor may also generate slice data based on the scan information.

As a result, the CT device 5 can acquire various functional information and morphological information as slice data. Therefore, the user can easily confirm the changed portion and the unchanged portion in each phase in the desired cross section while reducing the load on the processor.

Further, the processor may generate volume data by stacking slice data in the body axis direction.

As a result, the CT device 5 can acquire various functional images and morphological images as volume data. Therefore, the user can easily confirm the changed part and the unchanged part in the three-dimensional space in each phase.

(Other embodiments)
The present disclosure is not limited to the configuration of the above embodiment, and any configuration can achieve the functions shown in the claims or the functions of the configuration of the present embodiment. Is also applicable.

In the first embodiment, when scanning the same position in the body axis direction, the X-ray detector 42 may not be exactly the same position but may be displaced by about the slice thickness.

In the first embodiment, it is illustrated that a plurality of detectors in the X-ray detector 42 are divided into groups, but the detectors may not be divided into groups. In the CT device 5, different detectors scan approximately the same position in the body axis direction at intervals, generate a plurality of slice data or volume data based on the plurality of scan results, and based on the plurality of slice data or volume data. Time series information may be generated in.

In the first embodiment, the captured slice data and volume data may be transmitted from the CT device 5 to a medical image processing device that performs various image processing via the communication port of the CT device 5. Further, slice data and volume data may be transmitted to a server or the like on the network and stored in the server or the like. Further, the captured slice data and volume data may be output to an arbitrary storage medium via the external device connection port of the CT device 5.

In the first embodiment, the human body is exemplified as the subject, but it may be an animal body.

In the first embodiment, it is illustrated that various image processing is performed by the image processor 60, but it may be performed by the controller 20. Further, the image processor 60 and the controller 20 may be composed of one or three or more processors.

In the present disclosure, a program that realizes the function of the medical image imaging device of the first embodiment is supplied to the medical image imaging device via a network or various storage media, and is read and executed by a computer in the medical image imaging device. The program is also applicable.

The present disclosure is useful for a helical CT device, a medical image processing method, a medical image processing program, and the like, which can easily acquire 4D data of a subject and reduce invasiveness to the subject.

5 CT device 10 UI
20 Controller 30 Console 40 Gantry 41 X-ray tube 41r X-ray 42 X-ray detector 43 High voltage generator 50 Port 60 Image processor 70 Display 80 Memory dI, dI3 Time series information e, f Range EG Morphological image FG Function image L1, L2 line M subject MG composite image SG slice data

Claims (12)

A helical CT device that has multiple rows of detectors and performs helical scanning.
At the first time, a first detector that scans a part of the subject at the first position in the body axis direction and acquires the first scan information, and
At the second time, a second detector that scans a part of the subject at the first position in the body axis direction and acquires the second scan information, and
A processor that acquires time-series information at the first position in the body axis direction based on the first scan information and the second scan information.
Helical CT device including. The helical CT apparatus according to claim 1, further
Equipped with a single X-ray detector,
The first detector and the second detector are arranged parallel to the body axis direction and mounted on the X-ray detector.
Helical CT device. The helical CT apparatus according to claim 1 or 2.
The processor
Register the first scan information and the second scan information,
A helical CT device that acquires the time series information based on the registered first scan information and the second scan information. The helical CT apparatus according to any one of claims 1 to 3.
The processor is a helical CT device that generates functional information in the subject at the first time and the second time based on the time series information. The helical CT apparatus according to claim 4.
The functional information is a helical CT device including information on the flow velocity of body fluid in the subject. The helical CT apparatus according to any one of claims 1 to 5.
The processor is a helical CT device that generates morphological information based on the first scan information and the second scan information. The helical CT apparatus according to claim 6.
The processor
Register the first scan information and the second scan information,
A helical CT device that generates the morphological information based on the registered first scan information and the second scan information. The helical CT apparatus according to claim 6 or 7.
The processor is a helical CT device that generates the morphological information based on the synthesis of the first scan information and the second scan information. The helical CT apparatus according to any one of claims 1 to 8.
The processor is a helical CT device that generates slice data based on the scan information. The helical CT apparatus according to claim 9.
The processor is a helical CT device that generates volume data by stacking slice data in the body axis direction. A medical image processing method in a helical CT device that performs a helical scan.
At the first time, a part of the subject is scanned at the first position in the body axis direction, and the first scan information is acquired.
At the second time, a part of the subject is scanned at the first position in the body axis direction to acquire the second scan information.
A medical image processing method for acquiring time-series information at the first position in the body axis direction based on the first scan information and the second scan information. A medical image processing program for causing a computer to execute the medical image processing method according to claim 11.