JP2018094238A - X-ray ct device and medical image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray CT device and medical image processor capable of reducing a size of image data.SOLUTION: An X-ray CT device comprises: a reconstruction processing function 315 for generating CT image data based on plural pieces of projection data which are collected by detection of X-rays which are radiated to an analyte P from plural angles and then passed through the analyte P; and a storage device 32 for storing CT image data generated by the reconstruction processing function 315. The reconstruction processing function 315 generates tomographic image data whose size is smaller than a matrix size, as CT image data corresponding to a tomographic plane of the analyte P in a region to which the X-ray is radiated, at any angle out of plural angles, based on the preset matrix size.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to an X-ray CT apparatus and a medical image processing apparatus.

  In recent years, high-definition CT apparatuses capable of capturing CT images having higher spatial resolution than conventional X-ray CT apparatuses have attracted attention. A CT image taken by this high-definition CT apparatus has a larger data capacity than a conventional CT image. Therefore, it is required to store and transfer a CT image obtained in a high-definition CT apparatus with a data capacity as small as possible.

Japanese Patent Laying-Open No. 2015-6324

  An object of the present invention is to provide an X-ray CT apparatus and a medical image processing apparatus that can reduce the volume of image data.

  The X-ray CT apparatus of the embodiment includes an X-ray tube that irradiates a subject with X-rays from a plurality of angles, and an X-ray detection that detects X-rays that are irradiated by the X-ray tube and transmitted through the subject. A tomographic image by performing reconstruction processing on the projection data based on a preset matrix size, a data collection unit that collects projection data based on the X-rays detected by the X-ray detector A reconstruction processing unit that generates data, a storage unit that stores the tomographic image data, and a synthesis processing unit that generates CT image data having the matrix size together with the tomographic image data stored in the storage unit; .

1 is a block diagram showing the configuration of an X-ray CT apparatus according to a first embodiment. The figure which shows the structure of the X-ray detector which concerns on 1st Embodiment. 3 is a flowchart showing the operation of the X-ray CT apparatus according to the first embodiment. The figure which shows an example of the X-ray beam irradiated toward the X-ray detector from the X-ray tube which concerns on 1st Embodiment. The figure which shows the area | region in XY plane of the X-ray beam irradiated from the X-ray tube which concerns on 1st Embodiment by a two-dimensional coordinate. The figure which shows an example of the tomographic image data produced | generated by the reconstruction process function which concerns on 1st Embodiment. FIG. 3 is a diagram illustrating an example of frame image data stored in a storage device according to the first embodiment. The figure which shows an example of CT image data comprised by the tomographic image data and frame image data which were displayed on the display apparatus which concerns on 1st Embodiment. The block diagram which shows the structure of the X-ray CT apparatus and medical image processing apparatus which concern on 2nd Embodiment.

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

(First embodiment)
FIG. 1 is a block diagram showing a configuration of an X-ray CT apparatus 100 according to the first embodiment. The X-ray CT apparatus 100 according to the first embodiment includes an apparatus main body 10 and a console apparatus 30.

  The apparatus main body 10 includes a top plate 11 on which the subject P is placed, and a top plate driving device 12 that moves the top plate 11 horizontally and vertically. Further, the apparatus main body 10 generates X-rays by generating X-rays by irradiating the subject P placed on the top 11 with X-rays from a plurality of angles and detecting the X-rays transmitted through the subject P. A gantry 20 is provided. In addition, the apparatus main body 10 includes a high voltage generator 13 that supplies a voltage for generating X-rays to the gantry 20.

  The top plate driving device 12 includes a motor and an actuator for moving the top plate 11 horizontally and vertically. Then, the top plate driving device 12 moves the top plate 11 on which the subject P is placed to a position where X-ray irradiation by the gantry 20 is possible. The top plate drive device 12 is an example of a top plate drive unit.

  The gantry 20 includes a rotating frame 21, a rotation driving device 22, an X-ray tube 23, an X-ray detector 24, and a data acquisition circuit 25.

  The rotating frame 21 is an annular housing that rotatably supports the X-ray tube 23 and the X-ray detector 24 disposed to face the X-ray tube 23.

  The rotation drive device 22 includes a motor that drives the rotation frame 21 to rotate. Then, the rotation drive device 22 rotates the rotary frame 21 in the R direction indicated by the arrow with the isocenter IC as a rotation axis. The rotation drive device 22 is an example of a rotation drive unit.

  The X-ray tube 23 generates X-rays with a high voltage supplied from the high voltage generator 13. The X-ray tube 23 is rotated from the plurality of angles to the subject P while rotating around the subject P placed on the top plate 11 in the R direction with 360 ° rotation as one scan, for example. Irradiate the line.

  Next, the configuration of the X-ray detector 24 will be described with reference to FIG.

  FIG. 2 is a diagram illustrating an example of the X-ray detector 24 according to the present embodiment. The X-ray detector 24 is, for example, a multi-slice X-ray detector. Here, a horizontal direction perpendicular to the rotation axis of the rotating frame 21 is defined as an X direction, a vertical direction is defined as a Y direction, and a direction perpendicular to the X direction and the Y direction is defined as a Z direction.

  The X-ray detector 24 includes a plurality of X-ray detection elements that detect X-rays. The plurality of X-ray detection elements are arranged in a grid in the column direction S parallel to the Z direction shown in FIG. 2 and the channel direction C corresponding to the rotation direction of the rotating frame 21. The X-ray detector 24 detects X-rays transmitted through the subject P while rotating by X-ray irradiation from the X-ray tube 23, converts the X-rays into electric signals, and sends the electric signals to the data acquisition circuit 25. Output. The X-ray detector 24 is an example of an X-ray detector.

  Returning to the description of FIG.

  The data acquisition circuit 25 (Data Acquisition System: DAS) includes an amplification circuit that amplifies the signal output from the X-ray detector 24, an analog-digital conversion circuit that converts the amplified signal into a digital signal, and the like. The data collection circuit 25 generates projection data of one view for each predetermined angle (view angle) of the rotation frame 21 and collects projection data of a plurality of views during one scan by the rotation of the rotation frame 21. The data collection circuit 25 is an example of a data collection unit.

  The high voltage generator 13 includes an electric circuit such as an inverter. The high voltage generator 13 generates a high voltage and supplies it to the X-ray tube 23. The high voltage generator 13 is an example of a high voltage generator.

  The console device 30 includes a processing circuit 31, a storage device 32, a display device 33, and an input device 34. The console device 30 generates tomographic image data of the subject P and image data such as volume data based on the projection data collected by the apparatus main body 10. The console device 30 is an example of a console unit.

  The processing circuit 31 includes a top panel control function 311, a scan control function 312, an image processing function 313, a composition processing function 316, a display control function 317, and a system control function 318. The processing circuit 31 is an example of a processing unit.

  The top board control function 311 controls the top board driving device 12 to move the top board 11 horizontally and vertically. The top plate control function 311 is an example of a top plate control unit.

  The scan control function 312 controls various operations related to X-ray scanning, such as causing the high-voltage generator 13 to supply a high voltage to the X-ray tube 23 and irradiating the X-ray tube 23 with X-rays. The scan control function 312 is an example of a scan control unit.

  The image processing function 313 includes a preprocessing function 314 and a reconstruction processing function 315. The image processing function 313 generates image data based on the projection data of a plurality of views collected by the data collection circuit 25. The image processing function 313 is an example of an image processing unit.

  The preprocessing function 314 performs preprocessing such as offset correction, logarithmic conversion processing, and sensitivity correction on the projection data collected by the data collection circuit 25. The preprocessing function 314 is an example of a preprocessing unit.

  For example, the reconstruction processing function 315 performs pre-processing in one scan based on signals converted by a plurality of X-ray detection elements arranged in the channel direction C of one column in the column direction S of the X-ray detector 24. One tomographic image data corresponding to the tomographic plane of the subject P is generated from the projection data of a plurality of views. Further, the reconstruction processing function 315 performs one preprocessed scan based on signals converted by a plurality of X-ray detection elements arranged in the channel direction C of a plurality of columns in the column direction S of the X-ray detector 24. A plurality of pieces of tomographic image data or volume data is generated from projection data of a plurality of views. Then, when generating the tomographic image data, the reconstruction processing function 315 generates tomographic image data by performing a reconstruction process on the projection data based on a preset matrix size among a plurality of matrix sizes. . The reconstruction processing function 315 is an example of a reconstruction processing unit.

  The composition processing function 316 is used as the background image data of the tomographic image data generated by the reconstruction processing function 315 among the plurality of frame image data corresponding to the plurality of matrix sizes stored in advance in the storage device 32. Frame image data corresponding to the set matrix size is read. The composition processing function 316 generates CT image data having a preset matrix size by combining the read frame image data and the tomographic image data generated by the image processing function 313. The composition processing function 316 is an example of a composition processing unit.

  The display control function 317 performs various controls related to image display. Then, the display device 33 is controlled to display image data such as volume data generated by the image processing function 313 and CT image data generated by the composition processing function 316. The display control function 317 is an example of a display control unit.

  The system control function 318 controls the operation of the apparatus main body 10 and the console apparatus 30 to control the entire X-ray CT apparatus 100. The system control function 318 is an example of a system control unit.

  The storage device 32 includes, for example, a RAM (Random Access Memory), a semiconductor memory element such as a flash memory, a hard disk, an optical disk, and the like. The storage device 32 stores frame image data corresponding to a plurality of matrix sizes in advance. The storage device 32 stores each projection data collected by the gantry 20, each projection data preprocessed by the preprocessing function 314, tomographic image data and volume data generated by the image processing function 313, and the like. The storage device 32 is an example of a storage unit.

  The display device 33 includes a display circuit, a video memory, a CRT, a liquid crystal display, and the like. The display device 33 displays each image data such as volume data generated by the image processing function 313 and CT image data of each matrix size generated by the composition processing function 316. The display device 33 is an example of a display unit.

  The input device 34 includes, for example, a keyboard, a mouse, a trackball, a joystick, and the like. In order to obtain each image data, the input device 34 has various parts such as a part to be diagnosed of the subject P, a scanning method, the number of sheets, a slice interval, a tube current and a tube voltage, an effective visual field (FOV), a matrix size, and the like. An input for setting conditions, an input for moving the top 11 to an imaging position where the subject P can be scanned with X-rays, and the like are performed. The input device 34 is an example of an input unit.

  The processing functions of the top board control function 311, the scan control function 312, the image processing function 313, the composition processing function 316, the display control function 317, and the system control function 318 performed by the processing circuit 31 are programs that can be realized by a computer. It is stored in the storage device 32 in the form. The processing circuit 31 is a processor that realizes a processing function corresponding to each program by reading each program from the storage device 32 and executing the program. In other words, the processing circuit 31 in a state where each program is read has each processing function shown in the processing circuit 31 of FIG. In FIG. 1, the processing functions of the top panel control function 311, the scan control function 312, the image processing function 313, the composition processing function 316, the display control function 317, and the system control function 318 are combined in a single processing circuit 31. However, a plurality of processors may realize each processing function by realizing each program.

  Hereinafter, an example of the operation of the X-ray CT apparatus 100 will be described with reference to FIGS. 1 to 8.

  FIG. 3 is a flowchart showing the operation of the X-ray CT apparatus 100.

  The storage device 32 stores frame image data corresponding to a plurality of matrix sizes.

  As a condition for obtaining tomographic image data of the subject P from the input device 34 by examination, for example, “r” indicating a circular radius as an FOV for setting a region of a part necessary for diagnosis of the subject P, Various conditions for setting “1” indicating the number of sheets and “512 × 512” indicating the matrix size of the CT image data are input. In addition, when an input for starting an examination is performed after an input for moving the top plate 11 from the input device 34 to the imaging position and then stopping is performed, the X-ray CT apparatus 100 The operation is started (step S1).

  The system control function 318 controls the operations of the apparatus body 10 and the console device 30 based on various conditions input from the input device 34. The rotation drive device 22 drives the rotation frame 21 to rotate. The high voltage generator 13 supplies a high voltage to the X-ray tube 23. The X-ray tube 23 irradiates the subject P and the X-ray detector 24 placed on the top plate 11 with an X-ray beam.

  FIG. 4 is a diagram illustrating an example of an X-ray beam emitted from the X-ray tube 23 toward the X-ray detector 24.

  When “r” is set as the FOV, for example, a region E1 surrounded by a circle with a radius r centered on the isocenter IC in the XY plane including the isocenter IC becomes the FOV. The top plate 11 is stopped at a position where the tomographic plane of the diagnostic region of the subject P is included in the region E1.

  The X-ray tube 23 has an X-ray beam in a fan-shaped range indicated by two straight lines L1 and L2 having a central angle as the fan angle θ so that the region E1 can be irradiated with X-rays at any angle of the rotating frame 21. Set. The X-ray tube 23 irradiates the region E1 with X-rays at any angle of the rotating frame 21 while the rotating frame 21 rotates 360 degrees around the subject P, and a part of the rotating frame 21 The X-ray is irradiated to the region other than the region E1 at the angle of. The X-ray detector 24 detects X-rays that have passed through the subject P and outputs the signal to the data acquisition circuit 25.

  The rotation of the rotating frame 21 in the R direction with 180 degrees around the subject P placed on the top plate 11 and the rotation of the fan angle θ as one scan is performed from a plurality of angles. You may implement so that X-rays may be irradiated.

  The data collection circuit 25 collects projection data of a plurality of views based on the signals detected by the X-ray detector 24 (step S2 in FIG. 3).

  The storage device 32 stores projection data of a plurality of views collected by the data collection circuit 25. The preprocessing function 314 of the image processing function 313 preprocesses the projection data of a plurality of views collected by the data collection circuit 25 (step S3 in FIG. 3).

  The reconstruction processing function 315 generates tomographic image data based on a preset “512 × 512” matrix size and projection data of a plurality of views preprocessed by the preprocessing function 314.

  Here, an example of tomographic image data generated by the reconstruction processing function 315 based on the “512 × 512” matrix size will be described with reference to FIGS. 4 to 8.

  FIG. 5 is a diagram showing a region in the XY plane of the X-ray beam irradiated from the X-ray tube 23 in two-dimensional coordinates. This two-dimensional coordinate is a coordinate having an X axis in the X direction of the XY plane including the region E1 shown in FIG. 4 and an Y axis in the Y direction.

  In this two-dimensional coordinate, the region E2 corresponding to the CT image data having the “512 × 512” matrix size includes the region E1, for example, one side connecting the coordinate P1 (0, 0) and the coordinate P2 (511, 0). And a side connecting the coordinates P2 (511, 0) and the coordinates P3 (511, 511), a side connecting the coordinates P3 (511, 511) and the coordinates P4 (0, 511), and a coordinate P4 (0, 511) This is an area surrounded by a square composed of one side connecting the coordinates P1 (0, 0). The square surrounding the region E2 circumscribes the circle surrounding the region E1.

  The region E2 includes a region E1 and a region E3 around the region E1. The region E <b> 1 is a region where X-rays are irradiated at any angle of the rotating frame 21 and projection data is collected at all angles of the rotating frame 21. The region E3 is a region where X-rays are irradiated at some angles while the rotating frame 21 rotates 360 degrees, and projection data is collected at some angles.

  Based on the preset “512 × 512” matrix size and the projection data of a plurality of views preprocessed by the preprocessing function 314, the reconstruction processing function 315, as shown in FIG. Circular tomographic image data M1 is generated as image data corresponding to the tomographic plane (step S4 in FIG. 3).

  The reconstruction processing function 315 stores the tomographic image data M1 in the storage device 32 (step S5 in FIG. 3).

  Here, if the volume of the CT image data corresponding to the area E2 is 1, the volume of the tomographic image data M1 corresponding to the area E1 is about 80%.

  As described above, the generated tomographic image data M1 is stored in the storage device 32 based on each preset matrix size, so that it can be stored in a smaller capacity than the capacity required for storing the CT image data of the matrix size. It can be stored in the device 32. As a result, more tomographic image data can be stored in the storage device 32 than when CT image data of each matrix size is stored.

  In the storage device 32, as shown in FIG. 7, each pixel constituting the tomographic image data M1 has a “512 × 512” matrix size together with the tomographic image data M1 as image data corresponding to the region E3. For example, frame image data M2 that is set to the same pixel value that is equal to or less than the pixel value of, for example, one black color is stored.

  The pixel value is a value obtained by expressing the X-ray absorption coefficient of the substance as a relative value from the reference substance. In general, it is expressed as a relative value where water as a reference substance is 0, and air is expressed as -1000. And the pixel of the minimum unit which comprises CT image data is represented by a pixel value.

  Based on a preset “512 × 512” matrix size, the composition processing function 316 converts the frame image data corresponding to a plurality of matrix sizes stored in the storage device 32 to a “512 × 512” matrix size. Corresponding frame image data M2 is read (step S6 in FIG. 3).

  The composition processing function 316 reads the tomographic image data M1 stored in the storage device 32. Then, as shown in FIG. 8, the composition processing function 316 arranges the frame image data M2 around the tomographic image data M1, and combines the tomographic image data M1 and the frame image data M2 into a “512 × 512” matrix. CT image data M3 having a size is generated (step S7 in FIG. 3).

  The display device 33 displays the CT image data M3 having the “512 × 512” matrix size generated by the composition processing function 316 (step S8 in FIG. 3).

  When it is determined that the CT image data M3 displayed on the display device 33 is image data useful for diagnosis, an input to end the examination is performed from the input device 34, and the system control function 318 is input to the device main body 10 and the console device 30. The X-ray CT apparatus 100 ends the operation by stopping each of the operations (step S9 in FIG. 3).

  According to the first embodiment described above, the image data corresponding to the tomographic plane of the subject P in the region irradiated with X-rays at any angle of the rotating frame 21 based on a preset matrix size. As described above, tomographic image data can be generated and stored in the storage device 32. Further, based on a preset matrix size, image data corresponding to a region irradiated with X-rays at some angles of the rotation frame 21 is combined with the tomographic image data to have the matrix size, and the image data The frame image data in which all the pixels are set to the same pixel value equal to or less than the pixel value of each pixel constituting the tomographic image data can be stored in the storage device 32 in advance. Further, the tomographic image data generated based on the preset matrix size and the frame image data corresponding to the matrix size are read from the storage device 32, and the tomographic image data and the frame image data are combined to obtain the matrix size. The CT image data can be displayed on the display device 33.

  Accordingly, since the tomographic image data having a smaller capacity than the capacity necessary for storing the CT image data of each matrix size can be stored in the storage device 32, the CT image data of each matrix size is stored in the storage device 32. More tomographic image data can be stored.

(Second Embodiment)
FIG. 9 is a block diagram showing configurations of the X-ray CT apparatus 100a and the medical image processing apparatus 200 according to the second embodiment. Hereinafter, components having the same configuration and the same function as those of the X-ray CT apparatus 100 according to the first embodiment shown in FIG.

  The X-ray CT apparatus 100a of the second embodiment is different from the X-ray CT apparatus 100 shown in FIG. 1 in that, for example, a transmission circuit 35 that transmits tomographic image data to the medical image processing apparatus 200 via the network 300 is provided. It is a point. The X-ray CT apparatus 100a is an example of a medical image diagnostic apparatus. The transmission circuit is an example of a transmission unit.

  The medical image processing apparatus 200 according to the second embodiment includes a receiving circuit 36, a storage device 32a, a processing circuit 31a, a display device 33, and an input device 34.

  The receiving circuit 36 receives tomographic image data, volume data, and the like transmitted from the X-ray CT apparatus 100a via the network 300. The receiving circuit 36 is an example of a receiving unit.

  The storage circuit 32a includes, for example, a RAM (Random Access Memory), a semiconductor memory element such as a flash memory, a hard disk, an optical disk, and the like. The storage device 32a stores frame image data corresponding to a plurality of matrix sizes in advance. The storage device 32a stores tomographic image data, volume data, and the like received by the receiving unit 36. The storage device 32a is an example of a storage unit.

  The processing circuit 31a has a composition processing function 316a, a display control function 317, and a system control function 318a. The processing circuit 31a is an example of a processing unit.

  The composition processing function 316a reads the tomographic image data stored in the storage circuit 32a. In addition, the composition processing function 316 generates the tomographic image data among a plurality of frame image data corresponding to a plurality of matrix sizes stored in advance in the storage device 32a as background image data of the read tomographic image data. Therefore, frame image data corresponding to a matrix size set in advance is read out. Then, the synthesis processing function 316 generates CT image data having the matrix size by combining the read tomographic image data and frame image data. The composition processing function 316a is an example of a composition processing unit.

  The system control function 318a controls the operation of the receiving circuit 36, the storage device 32a, the processing circuit 31a, and the display device 33 to control the entire medical image processing apparatus 200. The system control function 318a is an example of a system control unit.

  The processing functions of the synthesis processing function 316a, the display control function 317, and the system control function 318a performed by the processing circuit 31a are stored in the storage device 32a in the form of a program that can be realized by a computer. The processing circuit 31a is a processor that implements a processing function corresponding to each program by reading and executing each program from the storage device 32a. In other words, the processing circuit 31a in the state where each program is read has each processing function shown in the processing circuit 31a of FIG. In FIG. 9, the processing functions of the synthesis processing function 316a, the display control function 317, and the system control function 318a have been described as being realized by a single processing circuit 31a. Each processing function may be realized by realizing the above.

  According to the second embodiment described above, tomographic image data generated by the X-ray CT apparatus 100a based on a preset matrix size can be stored in the storage device 32a of the medical image processing apparatus 200. Further, based on a preset matrix size, image data corresponding to a region irradiated with X-rays at some angles of the rotation frame 21 is combined with the tomographic image data to have the matrix size, and the image data The frame image data in which all the pixels are set to the same pixel value below the pixel value of each pixel constituting the tomographic image data can be stored in the storage device 32a in advance. Further, the tomographic image data generated based on the preset matrix size and the frame image data corresponding to the matrix size are read from the storage device 32a, and the tomographic image data and the frame image data are combined to generate the matrix size. The CT image data to be displayed can be displayed on the display device 33.

  As a result, the tomographic image data having a smaller capacity than the capacity required for storing the CT image data of each matrix size can be stored in the storage device 32a. Therefore, the CT image data of each matrix size is stored in the storage device 32a. More tomographic image data can be stored.

  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 novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

23 X-ray tube 24 X-ray detector 25 Data acquisition circuit 32, 32a Storage device 33 Display device 313 Image processing function 314 Preprocessing function 315 Reconfiguration processing function 316, 316a Composition processing function

Claims (5)

An X-ray tube that irradiates the subject with X-rays from a plurality of angles;
An X-ray detector for detecting X-rays irradiated by the X-ray tube and transmitted through the subject;
A data collection unit for collecting projection data based on X-rays detected by the X-ray detector;
A reconstruction processing unit that generates tomographic image data by performing reconstruction processing on the projection data based on a preset matrix size;
A storage unit for storing the tomographic image data;
A synthesis processing unit that generates CT image data having the matrix size together with the tomographic image data stored in the storage unit;
An X-ray CT apparatus comprising: In the storage unit, frame image data corresponding to the matrix size is stored in advance,
The said synthetic | combination process part reads the said tomographic image data and the said frame image data from the said memory | storage part, arrange | positions the said frame image data around the said tomographic image data, and produces | generates the said CT image data. X-ray CT system.   The X-ray CT apparatus according to claim 2, wherein the frame image data is configured by pixels set to a pixel value equal to or less than a pixel value of each pixel constituting the tomographic image data. A receiving unit for receiving tomographic image data generated based on a preset matrix size from an external medical image diagnostic apparatus;
A storage unit for storing the tomographic image data;
A synthesis processing unit that generates CT image data having the matrix size together with the tomographic image data stored in the storage unit;
A medical image processing apparatus comprising: In the storage unit, frame image data corresponding to the matrix size is stored in advance,
The said synthetic | combination process part reads the said tomographic image data and the said frame image data from the said memory | storage part, arrange | positions the said frame image data around the said tomographic image data, and produces | generates the said CT image data. Medical image processing apparatus.

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