JP4959358B2 - MPR display device and computed tomography apparatus - Google Patents

Description

  The present invention relates to an MPR display device and a computed tomography apparatus that generate and display a tomographic image of an arbitrary cross section from a plurality of tomographic images obtained from projection data relating to a subject.

  A computed tomography apparatus (hereinafter referred to as a CT apparatus) places a subject between an X-ray source and an X-ray detector and rotates the subject around an axis orthogonal to the X-ray optical axis. The X-ray source is irradiated with X-rays toward the subject, or the X-ray source and the X-ray detector are integrated to rotate around the subject while the X-rays are directed toward the subject. Projection data that is irradiated and transmitted from the subject is detected by an X-ray detector, and projection data relating to a three-dimensional region of the subject is collected.

  The CT apparatus reconstructs a plurality of continuous parallel cross-sectional images from the collected projection data relating to the three-dimensional region of the subject, and a cross-sectional image related to an arbitrarily designated cross-sectional position from the reconstructed cross-sectional images. And MPR (Multi-Planar Reconstruction) display is performed.

  The MPR display is already known as described in Patent Documents 1 and 2, for example. In the MPR display, an axial cross-sectional image that is an arbitrary cross-sectional image parallel to a plurality of cross-sectional images obtained from projection data relating to a three-dimensional region of the subject, an arbitrary straight line is designated on the axial cross-sectional image, and this designated straight line is designated. The oblique cross-section image, which is a cross-sectional image taken along the line, and an arbitrary straight line are designated on the oblique cross-sectional image, and a double oblique cross-sectional image, which is a cross-sectional image taken along the designated straight line, is generated and displayed on the display unit. .

  This MPR display is calculated again from the above-mentioned reconstructed cross-sectional images when the two designated cross-sectional positions arbitrarily specified on both ends of the straight line on the cross-sectional image are changed. Generate an image.

By the way, the CT apparatus as described above reconstructs a plurality of continuous parallel cross-sectional images from projection data relating to a three-dimensional region of a subject, and a cross-section at an arbitrary cross-sectional position from the reconstructed cross-sectional images. An image is generated, but since a cross-sectional image at an arbitrary cross-sectional position is generated by high-speed calculation, it is temporarily stored in a disk that is a sub-memory of a non-volatile memory that cannot be randomly accessed, and then the arithmetic processing CPU needs from the disk Cross-sectional image data is read at high speed, transferred to a volatile memory (also referred to as main memory) that can be randomly accessed, and calculation processing is performed to generate a cross-sectional image at an arbitrary cross-sectional position.
Japanese Patent Laying-Open No. 2005-300388 (see FIG. 1) Japanese Patent Laying-Open No. 2006-110059 (see FIG. 1)

  By the way, in recent years, so-called cone beam CT apparatus using a two-dimensional X-ray detector having substantially the same resolution in the vertical and horizontal directions has been used, and a plurality of cross-sectional images can be obtained by one scan. In addition, it is possible to obtain an isotropic cross-sectional image in which the resolution in the slice thickness direction is not much different from the direction along the actual slice.

  In addition, digital engineering techniques used for analysis using a plurality of continuous cross-sectional images as three-dimensional data are gradually spreading. Along with this, the number of three-dimensional matrices constituting a plurality of continuous cross-sectional images tends to increase more and more.

  As a result, in the conventional MPR display process, it is difficult to store the data amount of a plurality of continuous cross-sectional images in the work area of the volatile memory as described above. Therefore, the data of a plurality of cross-sectional images are temporarily stored in a disk which is a sub-memory of a non-volatile memory that cannot be randomly accessed, and the arithmetic processing CPU reads out the necessary cross-sectional image data from the disk at high speed. MPR display processing is performed. When the amount of cross-sectional image data for a plurality of sheets increases in this way, the frequency of disk loading / unloading (head withdrawal when the disk is stopped) increases, and the speed of MPR display processing becomes increasingly slower, and eventually MPR display. There is a problem that the switching time becomes longer.

  The present invention has been made in view of the above circumstances. An MPR display device and a computer tomography that can create an arbitrary cross-sectional image by high-speed processing and realize MPR display in a short switching time even if the data amount of the cross-sectional image increases. An object is to provide a photographing apparatus.

(1) In order to solve the above-described problem, an MPR display device according to the present invention stores a first storage unit that stores 3D data, which is a plurality of continuous parallel cross-sectional images, and the first storage unit. A cross-sectional image processing control means for creating a cross-sectional image by arbitrary designation from the 3D data, and a display means for displaying the arbitrary cross-sectional image created by the cross-sectional image processing control means,
The cross-sectional image processing control unit, from said 3D data stored in the first storage means, creating and second storage by interpolation calculation compressed 3D data with a reduced number of matrix by changing the voxel size in a non-integer multiple A compression means stored in the means, and an axial cross-sectional image creation that creates an axial cross-sectional image that is an arbitrary cross-sectional image parallel to the cross-sectional image of the 3D data from the 3D data or the compressed 3D data and displays it on the display means Means, first cross-sectional position setting means for setting an arbitrarily designated first cross-sectional position on the displayed axial cross-sectional image, and a first cross-sectional image cross-sectioned according to the first cross-sectional position from the compressed 3D data And a first cross-sectional image creating means for displaying on the display means.

According to such a configuration, compressed 3D data with a reduced number of matrices is generated by changing the voxel size by a non-integer multiple from the 3D data using interpolation calculation, and the first cross-sectional image (oblique cross-section) is generated from the compressed 3D data. Image) is created and displayed, so that when the arbitrarily designated first cross-sectional position is changed, the changed first cross-sectional image can be created in a short time, and MPR display with a short switching time can be realized.

  According to the present invention, a second cross-section position setting unit for setting a second cross-sectional position arbitrarily designated on the first cross-sectional image displayed on the display unit is newly added to the configuration of the cross-sectional image processing control unit. Further, a second cross-sectional image creating means for creating a second cross-sectional image sectioned according to the second cross-sectional position from the compressed 3D data and displaying it on the display means is added.

According to this configuration, compressed 3D data in which the number of matrices is reduced is generated by changing the voxel size by a non-integer multiple from 3D data using interpolation calculation, and a second cross-sectional image ( double oblique cross-sectional image is generated from this compressed 3D data. ) Is created and displayed, so that when the arbitrarily designated second cross-sectional position is changed, the changed second cross-sectional image can be created in a short time, and MPR display with a short switching time can be realized.

(2) Further, in the present invention, the first and second cross-sectional positions arbitrarily designated on the cross-sectional image are colored so that a correspondence relationship with the created first and second cross-sectional images can be understood. If they are displayed with different arrows, distinguishable marks, and symbols, the relationship between the arbitrarily designated cross-sectional position and the cross-sectional image can be easily grasped.

  Further, the compression means determines the voxel size and the number of matrices of the compressed 3D data so that the data amount of the compressed 3D data does not exceed a predetermined capacity in the second storage means. .

In addition, the compression means reduces the number of matrices so that the voxel size of the compressed 3D data is substantially the same in the three directions, thereby reducing the resolution of the first cross-sectional image and the second cross-sectional image displayed on the display means. Can be isotropic.

(3) Furthermore, the first storage means is a sub-memory that the cross-sectional image processing control means cannot randomly access, and the second storage means is a main memory that the cross-sectional image processing control means can randomly access The data amount of the compressed 3D data is a data amount that can be stored in the main memory. As a result, the compressed 3D data is stored in a randomly accessible main memory, so that the first cross-sectional image and the second cross-sectional image can be created at high speed, and MPR display can be realized in a short switching time.

(4) Furthermore, the present invention reconstructs projection data relating to a three-dimensional region of a subject and obtains a plurality of continuous parallel cross-sectional images, and an MPR display device having the above-described configuration. Is a computed tomography apparatus.

  As a result, an MPR display computed tomography apparatus with a short switching time can be realized.

  According to the present invention, it is possible to provide an MPR display device and a computer tomography apparatus that can create an arbitrary cross-sectional image by high-speed processing and realize MPR display in a short switching time even when the data amount of the cross-sectional image increases.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing an embodiment of a computed tomography apparatus including an MPR display device according to the present invention.

  The computed tomography apparatus collects projection data related to a three-dimensional region of a subject, and reconstructs the CT imaging apparatus 1 that reconstructs a plurality of continuous parallel sectional images from the collected projection data. The MPR display device 2 generates a cross-sectional image relating to an arbitrarily designated cross-sectional position from a plurality of cross-sectional images and displays the MPR.

  The CT imaging apparatus 1 is a conventionally well-known technique. For example, a radiation source 13 and a radiation detector 14 are arranged to face each other with a subject 12 placed on a turntable 11 interposed therebetween.

  For example, an X-ray source is used as the radiation source 13, and an X-ray beam shaped into a pyramid shape is irradiated toward the subject 12 using a collimator. The radiation detector 14 is, for example, a two-dimensional array type corresponding to a cone beam and having a plurality of X-ray detection elements arranged vertically and horizontally. The plurality of X-ray detection elements are arranged in a substantially planar shape substantially orthogonal to the X-ray irradiation axis.

  The radiation source 13 and the radiation detector 14 are attached to, for example, a ring-shaped rotating frame that is rotationally driven by a rotational driving device, or the X-ray irradiation axis from the radiation source 13 as a central axis as shown in the figure. The turntable 11 is moved up and down and rotated so that the X-ray beam generated from the radiation source 13 can be irradiated over the entire circumference of the subject 12. ing.

  Further, a projection data collection unit 15 and a reconstruction processing unit 16 are provided on the output side of the radiation detector 14.

  The projection data collection unit 15 converts signals output from the radiation detector 14 for each channel into digital signals and collects them as projection data.

  The reconstruction processing unit 16 reconstructs a plurality of continuous cross-sectional images from the projection data related to the three-dimensional region of the subject 12 collected by the projection data collecting unit 15, and sends it to the MPR display device 2 via the LAN 3. A plurality of continuous cross-sectional image data that is supplied or reconstructed based on a data request from the MPR display device 2 is transmitted.

  Note that the reconstruction processing unit 16 may have a configuration provided in the MPR display device 12 instead of the CT imaging device 1. Hereinafter, an example in which the reconstruction processing unit 16 is provided in the CT imaging apparatus 1 will be described.

  The MPR display device 2 is a normal computer, and includes a LAN interface 22 for transferring data between the LAN 3 and the bus line 21 in the device 2 and a CPU (Central Processing Unit). It comprises a cross-sectional image processing control unit 23, a main memory 24, a disk 25, a DVD drive 26, a display output interface 27, a keyboard 28, a pointing device 29 such as a mouse, a display 30 connected to the display output interface 27, and the like. Yes.

  The MPR display device 2 is provided with other components such as a casing, a power source, and the like, but the description is omitted because it is not directly related to the gist of the invention.

  The LAN interface 22 takes in a plurality of continuous cross-sectional image data transmitted from the CT imaging apparatus 1 or is reconfigured to be transmitted from the CT imaging apparatus 1 based on a data request instruction from the MPR display apparatus 2. It has a function to capture a plurality of continuous slice image data.

  The cross-sectional image processing control unit 23 is a unit that sequentially reads various programs stored in the main memory 24 and executes predetermined arithmetic processing, and functionally has a block configuration as shown in FIG. Have. The cross-sectional image processing control unit 23 stores a plurality of continuous parallel cross-sectional image data captured from the CT imaging apparatus 1 via the LAN interface 22 in the disk 25. Various programs for executing predetermined arithmetic processing are stored in the disk 25, read out at the time of execution, and stored in the main memory 24.

  The disk 25 is a non-volatile memory that is a secondary memory that cannot be randomly accessed and has a low access speed, but has a considerably larger memory capacity than the main memory 24. Here, random access means taking out data from an arbitrary address.

  On the other hand, the main memory 24 is a volatile memory that the cross-sectional image processing control unit 23 can randomly access at high speed, and has a memory capacity smaller than that of the disk 25. Therefore, the main memory 24 can perform high-speed work processing for generating a cross-sectional image of a cross-sectional position based on an arbitrary designation. However, as described above, the work memory area is small and some device is required.

  The DVD drive 26 has a function of reading and writing a DVD (abbreviation of Digital Versatile Disk) 31, which is a collective term for a large-capacity optical disk. It is possible to write a plurality of cross-sectional image data on the DVD 31 and then load it into the DVD drive 26, read a plurality of continuous cross-sectional image data from the DVD 31, and take them into the MPR display device 2.

  The display output interface 27 has a function of transferring a cross-sectional image based on an arbitrary designation obtained from a plurality of continuous cross-sectional image data by the cross-sectional image processing control unit 23 to the display unit 30, for example, if necessary, an image memory And a display control function.

  The keyboard 28 and the pointing device 29 have a function of inputting various control instruction data according to a program executed by the cross-sectional image processing control unit 23, inputting a position designation, and a necessary selection instruction.

FIG. 2 is a functional block configuration diagram of the cross-sectional image processing control unit 23 in the MPR display device 2.
Functionally, the sectional image processing control unit 23 includes a display flow control unit 41, a compression unit 42, an axial sectional image creation unit 43, a first sectional position setting unit 44, and a first sectional image creation unit 45. And a second cross-sectional position setting unit 46 and a second cross-sectional image creating unit 47.

  The display flow control unit 41 receives 3D data (three-dimensional data), which is a plurality of continuous cross-sectional images, from the CT imaging apparatus 1 via the LAN interface 22, or converts the 3D data stored in the DVD 31 into DVD. The data is read by the drive 26 and stored in the disk 25.

  The compression unit 42 reduces the data amount of 3D data stored in the disk 25 based on a required ratio (corresponding to a compression ratio), and can generate a cross-sectional image based on an arbitrarily designated cross-sectional position. Is stored in the main memory 24.

  The axial sectional image creation unit 43 creates an axial sectional image parallel to the sectional image of the 3D data from the 3D data or the compressed 3D data, and displays the axial sectional image on the display 30 via the display output interface 27.

  The first cross-section position setting unit 44 designates and inputs an arbitrary first cross-section position that is a straight line on the axial cross-sectional image displayed on the display device 30, and takes in the designated first cross-section position data. And an appropriate memory, for example, a function of setting in the main memory 24. The first cross-sectional image creating unit 45 performs cross-section based on the first cross-sectional position data set by the first cross-sectional position setting unit 44 from the compressed 3D data in the main memory 24, and is an oblique cross-section that is a first cross-sectional image. An image is created and displayed on the display 30 via the display output interface 27.

  The second cross-sectional position setting unit 46 designates and inputs an arbitrary second cross-sectional position that is a straight line on the oblique cross-sectional image displayed on the display device 30, and takes in the specified arbitrary second cross-sectional position data. And an appropriate memory such as the main memory 24. The second cross-sectional image creating unit 47 performs cross-section based on the second cross-sectional position data set by the second cross-sectional position setting unit 46 from the compressed 3D data in the main memory 24, and the double cross-leak that is the second cross-sectional image. A cross-sectional image is created and displayed on the display 30 via the display output interface 27.

  The cross-sectional image processing control unit 23 of the MPR display device 2 executes a series of processes according to a program and acquires an MPR display screen. For easy understanding, the cross-sectional image processing control unit 23 refers to FIG. The obtained MPR display screen will be described.

  The cross-sectional image processing control unit 23 of the MPR display device 2 creates and displays a display screen area obtained by dividing the MPR display screen of the display 30 into four parts based on screen division data predetermined in the program.

The following cross-sectional image is displayed in the display screen area divided into four. That is,
In the upper left display screen area shown in the figure, an axial sectional image P0,
In the lower left display screen area shown in FIG.
In the upper right display screen area in the figure, an oblique cross-sectional image P1b, which is a cross section based on different arbitrarily designated cross-section position data,
In the lower right display screen area shown in the figure, a double oblique cross sectional image P2 which is a cross section based on arbitrarily designated cross sectional position data is displayed from the oblique cross sectional image.

Next, the cross-sectional position based on arbitrary designation with respect to the cross-sectional image will be described.
Two cross-sectional positions L1a and L1b are designated and input on the axial cross-sectional image P0 displayed in the upper left of the figure. A cross-sectional image taken along the cross-sectional position L1a is an oblique cross-sectional image P1a shown in the lower left of the figure. The cross-sectional image taken along the cross-sectional position L1b is an oblique cross-sectional image P1b shown in the upper right part of the figure.

  A cross-sectional position L0 is designated and input on the oblique cross-sectional image P1a displayed in the lower left of the figure, and the cross-sectional image that is crossed under this designated input is a cross-sectional image corresponding to the axial cross-sectional image P0 shown in the upper left of the figure. Is displayed.

  The cross-sectional positions L0 and L2 are designated and input on the oblique cross-sectional image P1b displayed in the upper right part of the figure, and the cross-sectional image sectioned based on the designated and inputted cross-sectional position L0 is the axial cross-sectional image shown in the upper left part of the figure. A cross-sectional image corresponding to P0 is displayed, and the cross-sectional image cross-sectioned based on the designated and input cross-sectional position L2 is a double-oblique cross-sectional image P2 shown in the lower right part of the figure.

  The change of the designated cross-sectional positions L1a and L1b is determined when the operator inputs a change request for the point A and the angle φ as an intersection using the pointing device 29, for example, and is displayed as a display position. These designated sectional positions L1a and L1b are straight lines orthogonal to each other. In the initial default where there is no designation input, the point A of the axial cross-sectional image P0 shown in the upper left of the figure is the center, and the angle φ is 0 °.

  Also, the change in the designated cross-sectional position L0 is determined by the operator's change request input as described above, and is displayed as a horizontal line display position. The default is center. Note that L0 on the oblique cross-sectional image P1a and L0 on the oblique cross-sectional image P1b are in the same position in the vertical direction, and when one is changed, the other changes in conjunction with it.

  The change of the designated cross-sectional position L2 is determined by the operator using the pointing device 29 to input a change request for the point B and the angle θ, and is displayed as a display position. By default, point B is the center and angle θ is 0 °.

  In FIG. 3, arrows are attached to the designated cross-sectional positions L0, L1a, L1b, and L2 so that the correspondence and orientation with the cross-sectional images can be understood. You may attach and display an arrow with a different color so that correspondence and direction may be understood. This arrow does not have to be displayed in a state of being completely coincident with the designated sectional position. Furthermore, instead of an arrow, another identifiable mark or symbol may be attached and displayed.

  Next, the operation of the MPR display device 2 configured as described above will be described with reference to FIGS.

  The cross-sectional image processing control unit 23 of the MPR display device 2 executes a series of processes according to a program. First, the cross-sectional image processing control unit 23 executes the display flow control unit 41. The display flow control unit 41 takes in 3D data (three-dimensional data), which is a plurality of continuous cross-sectional images, from the CT imaging apparatus 1 via the LAN 3 and the LAN interface 22, and stores them in the disk 25 (S1). Alternatively, 3D data stored on the DVD 31 may be read by the DVD drive 26 and stored in the disk 25.

  The cross-sectional image processing control unit 23 stores the 3D data, which is a plurality of continuous parallel cross-sectional images, on the disk 25, and then executes the compression unit 42.

  The compression unit 42 creates compressed 3D data from the 3D data (S2). FIG. 5 is a diagram for explaining compression. The compression processing by the compression unit 42 is performed by converting 3 × M × M × K 3D data (see FIG. 5A) of K × M × M cross-sectional images into a 3D data in real space. This is a process of converting into compressed 3D data (see FIG. 5B) with the number of matrices Mc × Mc × Kc without changing.

  At the time of compression processing of a cross-sectional image, the size (mm) of each voxel constituting 3D data of the number of matrices M × M × K is Δx, Δy (= Δx), Δz before processing, and Δxc after processing. , Δyc, Δzc.

  Therefore, when the operator inputs the above-described M, K, Δx, Δy, Δz, which is supplementary information of 3D data, from the keyboard 28, the compression unit 42 is based on the following predetermined calculation formulas. Mc, Kc, Δxc, Δyc, Δzc are calculated from Δx, Δy, Δz.

  As a calculation formula, if Umax is a predetermined data amount (bytes) and one point value of 3D data (a value corresponding to one voxel) is represented by 2 bytes, the relationship between M, K and Umax Can be divided into two cases: 2 × M × M × K ≦ Umax and 2 × M × M × K> Umax. Umax is a predetermined value such that the compressed 3D data fits in the remaining storage capacity obtained by subtracting at least the program data and the processing work storage area from the total storage capacity of the main memory 24, for example. This is called a memory free area in the memory 24. As a result, when the main memory 24 is also used for other processing, the value is reduced considering that amount.

* If 2 × M × M × K ≦ Umax,
There is sufficient free space in the main memory 24. as a result
Mc = M, Kc = K, Δxc = Δx, Δyc = Δy, Δzc = Δz (1)
And That is, 3D data is directly used as compressed 3D data.

* If 2 × M × M × K> Umax,
The free space in the main memory 24 is insufficient. Therefore, the ratio Re (corresponding to the compression ratio) between Umax and 2 × M × M × K is obtained.
Re = Umax / (2 × M × M × K) (2)
Here, as an intermediate calculation, a temporary voxel size Δ is obtained when the compressed voxel is a cube.
Δ = {(Δx × Δy × Δz) / Re} ^1/3 (3)
Then, using the obtained temporary voxel size Δ, the matrix size is calculated by the following equations (4) and (5).
Mc = INT {(M−1) · Δx / Δ} (4)
Kc = INT {(K−1) · Δz / Δ} (5)
Next, when the temporary voxel size Δ is used, the region size in the real space is cut off, so that Δxc, Δyc, Δzc are adjusted to be slightly larger than Δ by the following calculation so as not to be cut off. To do.

Δxc = (M−1) · Δx / (Mc−1) (6)
Δyc = Δxc (7)
Δzc = (K−1) · Δz / (Kc−1) (8)
According to the above calculation formula, Δzc and Δxc (and Δyc) are only slightly adjusted, and are substantially the same as the temporary voxel size Δ and are isotropic.

  Further, the compression unit 42 performs interpolation calculation from the 3D data using the parameters obtained as described above, creates final compressed 3D data, and stores it in the main memory 24. As a result, the compressed 3D data is created and stored in the main memory 24 without changing the area size of the 3D data in the real space. Work processing can be performed.

  Subsequently, after storing the compressed 3D data in the main memory 24, the cross-sectional image processing control unit 23 uses the keyboard 28 and the pointing device 29 to create cross-sectional positions L0, L1a, When L1b and L2 are designated and input, the first cross-section position setting unit 44 and the second cross-section position setting unit 46 including the axial cross-section position take in the cross-section positions and set them in an appropriate memory and display them on the display 30. (S3). The first setting is the default position.

  After setting the cross-sectional position as described above, the cross-sectional image processing control unit 23 executes the axial cross-sectional image creation unit 43 to create the axial cross-sectional image P0 (S4).

  That is, the axial cross-sectional image creation unit 43 selects the Mc × Mc cross-sectional image at the z position closest to the set cross-sectional position L0 from the compressed 3D data, and converts it into a display matrix, thereby converting the axial cross-sectional image P0. Is displayed on the display 30 (see FIG. 3). At this time, interpolation may be performed in the z direction.

  Subsequently, the cross-sectional image processing control unit 23 executes the first cross-sectional image creation unit 45 to create an oblique cross-sectional image P1a (S5). The first cross-sectional image creation unit 45 creates an oblique cross-sectional image P1a from the compressed 3D data by converting the display matrix set on the set cross-sectional position L1a while performing interpolation calculation, This is displayed on the display 30 (see FIG. 3).

  The first cross-sectional image creating unit 45 creates an oblique cross-sectional image P1b (S6). The first cross-sectional image creation unit 45 creates an oblique cross-sectional image P1b by performing conversion while performing interpolation calculation on the display matrix set on the set cross-sectional position L1b from the compressed 3D data, This is displayed on the display 30 (see FIG. 3).

  Furthermore, the cross-sectional image processing control unit 23 executes the second cross-sectional image creating unit 47 to create a double oblique cross-sectional image P2 (S7). The second cross-sectional image creating unit 47 creates a double oblique cross-sectional image P2 from the compressed 3D data by converting the display matrix set on the set cross-sectional position L2 while performing interpolation calculation. Is displayed on the display 30 (see FIG. 3).

  After creating the required cross-sectional image as described above, it is determined whether or not a cross-section position change request is input from the keyboard 28 and the pointing device 29 (S8). Is determined (S9). If there is an end request, the process ends. If not, the process returns to step S8.

  In step S8, when there is a change request, the process proceeds to step S3, and the designation input of the cross-sectional position accompanying the change request is fetched. Then, the cross-sectional image processing control unit 23 continuously executes a series of processes after step S4, creates a required cross-sectional image, and returns to step S8.

  Accordingly, when the operator changes the cross-sectional position using the keyboard 28 and the pointing device 29 as described above, the cross-sectional positions L0, L1a, L1b, and L2 are switched in a short time according to the changed cross-sectional position, and sequentially The cross-sectional images P0, P1a, P1b, and P2 are switched and displayed almost in real time.

  Therefore, according to the embodiment as described above, the voxel size and the number of matrices of the compressed 3D data are automatically determined so as to be within the capacity Umax in the free area of the main memory 24, and the compressed 3D data is created. Therefore, the storage capacity of the main memory 24 can be used effectively.

  Further, since each cross-sectional image for MPR display is calculated and created from the compressed 3D data stored in the main memory 24, a cross-sectional image for MPR display can be created at high speed even if the amount of data increases, and a short switching time can be obtained. MPR display can be realized.

  In addition, since the compressed 3D data is generated approximately isotropically, the resolution of the oblique cross-sectional image (first cross-sectional image) and the double oblique cross-sectional image (second cross-sectional image) displayed by MPR becomes isotropic. This can avoid a cross-sectional image flowing in one direction.

  Furthermore, by displaying the designated cross-sectional position for creating a cross-sectional image using arrows of different forms or colors, or other marks or symbols, the correspondence between each designated cross-sectional position and each cross-sectional image and the cross-sectional image You can intuitively grasp the direction of the.

(Other embodiments)
(1) In the above embodiment, the voxel size and the number of matrices are calculated according to the above-described predetermined calculation formula, but are not limited to this calculation formula. The voxel size Δzc is substantially the same as Δxc, but it may be completely the same size. For example, the formulas (6) and (8) were calculated so as not to cut off, but instead of the formulas (6) and (8), respectively.
Δxc = Δ (6 ′)
Δzc = Δ (8 ′)
It is good. In this case, the region is cut off, but the voxel size is a regular cube having the same size in all three directions.

(2) In the above embodiment, the cross-sectional position L2 of the double oblique cross-sectional image P2 is displayed on the upper right P1b image in FIG. 3, but L2 may be designated and input on the lower left P1a image. . Further, the operator may be able to select either P1a or P1b.

(3) In the above embodiment, only an axial cross-sectional image may be created from uncompressed 3D data. The reason is that the axial cross-sectional image can be calculated from only one cross-sectional image of 3D data or two adjacent cross-sectional images, and the adjacent cross-sectional position is changed even when the cross-sectional position is changed. This is because the frequency of loading / unloading to 24 can be reduced. That is, if a small range before and after the display cross-sectional position is loaded in advance, it is possible to cope with a change in the cross-sectional position. Thereby, the display of an axial section can be made high-quality, maintaining high-speed switching.

(4) In the above embodiment, the axial sectional image and the oblique sectional image are displayed as a whole with the center of the compressed 3D data as the center of the display screen. It is also possible to shift the center of the display to a desired point from the center of the display screen, and further, the display can be enlarged or reduced at a desired enlargement ratio or reduction ratio and displayed on the display 30. In this case, the MPR display can be changed almost in real time by changing and inputting the display center and the enlargement ratio or reduction ratio in the compressed 3D data.

  Note that when the cross-sectional image is enlarged and displayed, the compressed 3D data may be created only in the area to be enlarged and displayed. Thereby, even if it compresses and data amount is reduced, a high-resolution MPR display can be obtained.

(5) In the above embodiment, the CT imaging device 1 and the MPR display device 2 are completely separated. However, for example, a configuration in which the MPR display device 2 is incorporated in the CT imaging device 1 may be used. At this time, the MPR display device 2 as an independent unit may be incorporated, or the processing device for reconfiguration processing of the CT imaging device 1 may have the functional blocks of the program shown in FIG.

(6) Further, in the above embodiment, the MPR display device 2 creates and displays an axial cross-sectional image, an oblique cross-sectional image, and a double oblique cross-sectional image from the compressed 3D data. When a quality command or a save command is issued, for example, four cross-sectional images shown in FIG. It may be displayed, or may be stored on the disk 25 as an MPR image for storage. That is, when the operator changes the cross-sectional position based on an arbitrary designation, each cross-sectional image is displayed on the display device 30, and when the displayed cross-sectional image is an optimal cross-sectional image, a high-quality command or a storage command is displayed. , The MPR image is recreated and displayed, or stored in the disk 25 as a storage MPR image.

  According to such a configuration, the MPR display has a short switching time, and the MPR image to be recreated or saved is created from 3D data that is not compressed, so that it can be generated as a high-quality MPR image.

  In addition, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.

  In addition, the embodiments can be implemented in combination as much as possible, and in that case, the effect of the combination can be obtained. Further, each of the above embodiments includes various higher-level and lower-level inventions, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, when an invention is extracted because some constituent elements can be omitted from all the constituent elements described in the means for solving the problem, the omitted part is used when the extracted invention is implemented. Is appropriately supplemented by well-known conventional techniques.

1 is a hardware configuration diagram showing an embodiment of a computer tomography apparatus according to the present invention. The figure which shows an example of the functional block structure implement | achieved by the cross-sectional image process control part of the MPR display apparatus shown in FIG. Explanatory drawing of the MPR display screen displayed on the display shown in FIG. The figure which shows an example of the processing flow by a MPR display apparatus. The figure explaining compression by a MPR display apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... CT imaging device, 2 ... MPR display device, 3 ... LAN, 22 ... LAN interface, 23 ... Cross-sectional image processing control part, 24 ... Main memory, 25 ... Disk, 26 ... DVD drive, 27 ... Display output interface, 28 DESCRIPTION OF SYMBOLS ... Keyboard, 29 ... Pointing device, 30 ... Display, 31 ... DVD, 41 ... Display flow control part, 42 ... Compression part, 43 ... Axial cross-section image creation part, 44 ... 1st cross-section position setting part, 45 ... 1st Cross-sectional image creation unit, 46 ... second cross-section position setting unit, 47 ... second cross-sectional image creation unit.

Claims (7)

In an MPR display device that creates an arbitrary cross-sectional image from 3D data that is a plurality of continuous parallel cross-sectional images and displays the MPR,
The first storage means for storing the 3D data, the cross-sectional image processing control means for creating a cross-sectional image by arbitrary designation from the 3D data stored in the first storage means, and the cross-sectional image processing control means Display means for displaying an arbitrary cross-sectional image,
The cross-sectional image processing control means
From the 3D data stored in the first storage unit, a compressing means for storing compressed 3D data with a reduced number of matrix by changing the voxel size in non-integral multiple in the second storage means is generated by interpolation calculation,
From the 3D data or the compressed 3D data, an axial cross-sectional image creation unit that creates an axial cross-sectional image that is an arbitrary cross-sectional image parallel to the cross-sectional image of the 3D data and displays the axial cross-sectional image on the display unit;
First section position setting means for setting an arbitrarily designated first section position on the displayed axial section image;
An MPR display device, comprising: first cross-sectional image creation means for creating a first cross-sectional image sectioned according to the first cross-sectional position from the compressed 3D data and displaying the first cross-sectional image on the display means. The MPR display device according to claim 1,
The cross-sectional image processing control means
Second section position setting means for setting an arbitrarily designated second section position on the first section image displayed on the display means;
An MPR display device, further comprising: a second cross-sectional image creating unit that creates a second cross-sectional image sectioned according to the second cross-sectional position from the compressed 3D data and displays the second cross-sectional image on the display unit. The MPR display device according to claim 1 or 2,
The first and second cross-sectional positions arbitrarily designated on the cross-sectional image are arrows and identifiable marks of different colors so that the correspondence relationship with the created first and second cross-sectional images can be understood. An MPR display device characterized by displaying with a symbol. The MPR display device according to claim 1 or 2,
The MPR display device characterized in that the compression means determines the voxel size and the number of matrices of the compressed 3D data so that the data amount of the compressed 3D data does not exceed a predetermined capacity in the second storage means . In the MPR display device according to any one of claims 1, 2, and 4,
The MPR display device according to claim 1, wherein the compression means reduces the number of matrices so that the voxel size of the compressed 3D data is substantially the same in three directions. In the MPR display device according to any one of claims 1 to 5,
The first storage means is a sub-memory that cannot be randomly accessed by the cross-sectional image processing control means, and the second storage means is a main memory that can be randomly accessed by the cross-sectional image processing control means, and the compressed 3D data The MPR display device is characterized in that the amount of data is the amount of data that can be stored in the main memory. A CT imaging device that reconstructs projection data relating to a three-dimensional region of a subject and obtains a plurality of continuous parallel cross-sectional images;
A computed tomography apparatus comprising: an MPR display device having the configuration according to any one of claims 1 to 6.

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