JP5179897B2 - X-ray CT system - Google Patents

Description

  The present invention relates to an X-ray CT apparatus.

  Conventionally, an X-ray computed tomography apparatus (hereinafter referred to as an X-ray CT apparatus, CT; Computed Tomography) is based on X-ray intensity distribution data obtained by detecting the intensity of X-rays transmitted through a subject. By reconstructing and providing tomographic images showing morphological information of human tissues in the subject on the irradiated surface (tomographic plane), such as diagnosis, treatment, and surgical planning It plays an important role in many medical practices.

  An X-ray CT apparatus includes a gantry rotating unit having an X-ray tube and an X-ray detector disposed opposite to each other around an internal space into which a subject lying on a couch top is inserted, and a gantry rotating unit. And a gantry fixing portion that is rotatably supported. The X-ray CT apparatus rotates the gantry rotating unit around the subject at the time of imaging, and the X-ray tube disposed on the gantry rotating unit irradiates the subject with X-rays from multiple directions, The X-ray detector detects the intensity of X-rays irradiated from multiple directions and transmitted through the subject.

  The X-ray CT apparatus performs back projection (back projection) after correcting the X-ray intensity distribution data (pure raw data) from multiple directions detected by the X-ray detector, such as sensitivity correction by preprocessing. Or image convolution by convolution. Currently, an X-ray detector in which a plurality of rows of detection elements (for example, 16 rows, 64 rows, etc.) are arranged along the body axis direction of the subject has been put into practical use, so that an image in a wide area of the subject can be obtained. Can be collected at high speed. When an X-ray detector in which a plurality of rows of detection elements are arranged is used, pure raw data collected in units of columns is back-projected in units of columns and reconstructed for each tomographic image.

  In the X-ray CT apparatus, during imaging, the gantry rotating unit is rotated, and the bed is continuously moved in the body axis direction of the subject so that a wider area can be imaged. Helical scanning is performed to reconstruct a plurality of tomographic images along the body axis direction to obtain a three-dimensional image (volume image). The three-dimensional image creation process is performed as a post-process after the reconstruction process and the image data storage process.

  As described above, in the X-ray CT apparatus, it is necessary to perform image reconstruction by immediately and surely processing a huge amount of data (that is, a huge amount of detection data for a plurality of columns over a wide range in a helical scan). Therefore, for example, Patent Document 1 discloses a technique for dividing a huge amount of pure raw data and processing preprocessing and reconstruction processing in parallel.

  On the other hand, in recent years, an X-ray detector (for example, 256 rows) in which detection elements are arranged in more rows in the body axis direction has entered a practical stage. When this X-ray detector is used, data including all the region of interest (for example, the heart, etc.), that is, the region of interest is obtained by conventional scanning in which imaging is performed by rotating the gantry rotating unit one time without performing imaging by helical scanning. It is possible to collect data required for reconstructing the three-dimensional image at a time. In addition, by performing conventional scanning continuously, it is possible to collect data for reconstructing a three-dimensional image along the time series of the region of interest at a time.

JP 2007-315 A

  By the way, the above-described conventional technique is required for reconstructing a three-dimensional image including a region of interest by a conventional scan using an X-ray detector in which detection elements are arranged in multiple rows in the body axis direction. There is a problem that even if data is collected at a time, a three-dimensional image cannot be immediately reconstructed.

  For example, the amount of pure raw data detected and collected by an X-ray detector in which 256 rows of detection elements are arranged in the body axis direction is the X-ray in which detection elements such as 16 rows and 64 rows are arranged in the body axis direction. Compared with the amount of pure raw data detected and collected by the detector, it becomes much larger, and with the conventional technology described above, the pure raw data is divided and processed in parallel by columns to reconstruct a tomographic image. Even when a three-dimensional image is generated, the time required is in units of several seconds and is not data at the same time, and therefore, it does not satisfy the immediacy required for making a diagnosis using an X-ray CT apparatus.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and an X-ray CT apparatus capable of immediately reconstructing a three-dimensional image and storing it as three-dimensional image data. The purpose is to provide.

In order to solve the above-described problems and achieve the object, the present invention provides an X-ray CT apparatus for reconstructing an image based on projection data indicating the intensity distribution of X-rays transmitted through a subject, An X-ray detector in which a plurality of detector element arrays each including a plurality of X-ray detector elements are arranged, an X-ray tube that exposes X-rays, and the X-ray detector are rotated around the subject to obtain an X-ray Data collection means for collecting projection data for each irradiation direction, storage means for storing three-dimensional volume data, and projection data for a plurality of channels and a plurality of columns corresponding to the X-ray irradiation direction collected by the data collection means And a back projection processing means configured to repeat the back projection processing on the three-dimensional volume data stored in the storage means and repeat this back projection processing for each X-ray irradiation direction. To do.

The present invention also relates to an X-ray CT apparatus for reconstructing an image based on projection data indicating the intensity distribution of X-rays transmitted through a subject, and comprising a plurality of channels of X-ray detection elements. Data collection that collects projection data for each X-ray irradiation direction by rotating an X-ray detector in which a plurality of element rows are arranged, an X-ray tube for exposing X-rays, and the X-ray detector around the subject. Means, data distribution means for distributing the projection data collected by the data collection means in units of X-ray irradiation direction, and projection data sent from the data distribution means via the data transmission means A plurality of preprocessing means for performing correction processing, a plurality of backprojection processing means for performing backprojection processing on the projection data sent from the preprocessing means via the data transmission means, and the backprojection processing means With backprojection processing Data that was synthesized and characterized in that and an image combining processing means for generating a 3-dimensional image data.

According to the present invention, it is possible to collectively generate a three-dimensional image for each X-ray irradiation direction by reading weighting data once, and to immediately reconstruct the three-dimensional image and store it as three-dimensional image data. Is possible.

According to the present invention, X-ray intensity distribution data for each X-ray irradiation direction and projection data for each X-ray irradiation direction can be collectively processed, and a three-dimensional image is immediately reconstructed to obtain three-dimensional image data. Can be stored as.

  Exemplary embodiments of an X-ray CT apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.

  First, the structure of the X-ray CT apparatus in a present Example is demonstrated using FIG. FIG. 1 is a diagram for explaining the configuration of the X-ray CT apparatus in the present embodiment. As shown in FIG. 1, the X-ray CT apparatus in the present embodiment includes a gantry device 10, a couch device 20, and a console device 30.

  The gantry device 10 is a device that collects data by exposing the subject P to X-rays, and includes a gantry rotating unit 12 and a gantry fixing unit 11.

  The gantry rotating unit 12 is an annular frame that rotates continuously at a high speed around the subject P. The X-ray tube 13 and the X-ray detector 14 are arranged to face each other, and the first data A collection unit 15 is provided.

  The X-ray tube 13 is a vacuum tube that generates X-rays by a high voltage supplied from a high voltage generation unit 17 described later. As the gantry rotation unit 12 rotates, an X-ray fan beam or cone beam is applied to the subject. Irradiate P from multiple directions.

  The X-ray detector 14 is a two-dimensional array type detector that detects X-ray intensity distribution data indicating the intensity distribution of X-rays that have passed through the subject P, and includes X-ray detection elements for a plurality of channels. A plurality of rows of X-ray detection elements are arranged along the body axis direction of the subject P (Z-axis direction shown in FIG. 1). Specifically, in the present embodiment, the X-ray detector 14 has X-ray detection elements arranged in multiple rows such as 256 rows along the body axis direction of the subject P, and the subject P is spread over a wide range. The transmitted X-ray intensity distribution data is detected.

  The first data collecting unit 15 in the gantry rotating unit 12 performs projection processing and A / D conversion processing on the X-ray intensity distribution data detected by the X-ray detector 14 to generate projection data.

  The gantry fixing unit 11 rotatably supports the gantry rotating unit 12, and includes a second data collection unit 16, a high voltage generation unit 17, and a gantry driving unit 18.

  The second data collection unit 16 in the gantry fixing unit 11 receives the projection data generated by the first data collection unit 15 and transmits the received data to a preprocessing unit 34 (described later) of the console device 30.

  The high voltage generating unit 17 is a device that supplies a high voltage to the X-ray tube 13, and the gantry driving unit 18 rotates the gantry rotating unit 12 to rotate the X on the circular orbit around the subject P. The tube 13 and the X-ray detector 14 are turned.

  The couch device 20 is a device on which the subject P is placed, and includes a couchtop 22 and a couch driving unit 21. The top plate 22 is a plate on which the subject P is placed at the time of imaging, and the bed driving unit 21 is a device that moves the top plate 22 in the Z direction.

  The console device 30 is a device that accepts the operation of the X-ray CT apparatus by the operator and reconstructs an image representing the internal form of the subject P from the projection data collected by the gantry device 10. Display unit 32, scan control unit 33, preprocessing unit 34, projection data storage unit 35, reconstruction auxiliary processing unit 36, image reconstruction unit 37, image storage unit 38, and system control unit 39 Is provided.

  The input unit 31 is used for inputting an instruction from an operator such as a mouse or a keyboard, for example, setting of an imaging method, setting of a region of interest (for example, a region including the heart of the subject P), The image processing setting after reconstruction is received and input from the operator. As an imaging method, a conventional scan in which imaging is performed by rotating the gantry rotating unit 12 once while the position of the subject P is fixed, and the gantry rotating unit 12 is continuously performed while the position of the subject P is fixed. There are a continuous conventional scan for rotating and taking a picture, a helical scan for taking an image by continuously rotating the gantry rotating unit 12 while moving the top plate 22 by the bed driving unit 21 and the like. Further, the image processing after reconstruction includes processing for extracting an arbitrary cross section from the reconstructed three-dimensional image, and generating a two-dimensional image by volume rendering.

  The display unit 32 displays image data stored in an image storage unit 38 to be described later.

  The scan control unit 33 controls the operations of the first data collection unit 15, the second data collection unit 16, the high voltage generation unit 17, the gantry drive unit 18, and the bed drive unit 21 under the control of the system control unit 39 described later. Control. That is, the scan control unit 33 drives the gantry driving unit 18 to move the subject P lying on the top plate 22 to the internal space of the gantry rotating unit 12 and drives the gantry driving unit 18 to drive the gantry rotating unit 12. , And a high voltage is generated from the high voltage generator 17 to irradiate X-rays from the X-ray tube 13.

  Further, the scan control unit 33 is configured to collect the X-ray intensity distribution data by the first data collection unit 15, the data transmission format from the first data collection unit 15 to the second data collection unit 16, and the second data collection unit 16. The transmission format of data to the pre-processing unit 34 to be described later is controlled.

  For the projection data generated by the first data collection unit 15 and transmitted by the second data collection unit 16, the preprocessing unit 34 performs correction processing such as logarithmic conversion processing, offset correction, sensitivity correction, and beam hardening correction. The projection data storage unit 35 stores the projection data corrected by the preprocessing unit 34.

  The reconstruction auxiliary processing unit 36 reads out the projection data corrected by the projection data storage unit 35 via the preprocessing unit 34, and performs a convolution process using weighted data as preprocessing for image reconstruction. And the convolution processed projection data is transmitted to the image reconstruction unit 37 described later.

  The image reconstruction unit 37 reconstructs a three-dimensional image from the convolution processed projection data received from the reconstruction auxiliary processing unit 36 received from the reconstruction auxiliary processing unit 36, and reconstructs the reconstructed three-dimensional image. The data is transmitted to the configuration auxiliary processing unit 36. This will be described in detail later.

  Here, the reconstruction auxiliary processing unit 36 receives the three-dimensional image data generated by the image reconstruction unit 37, performs an artifact correction process and an image process according to an instruction from the operator, and an image storage unit 38. The processed three-dimensional image data is stored.

  The system control unit 39 controls the X-ray CT apparatus as a whole by controlling the operations of the gantry device 10, the couch device 20, and the console device 30. That is, the system control unit 39 collects X-ray intensity distribution data from the gantry device 10 by controlling the scan control unit 33 based on an instruction of the operator input by the input unit 31. Further, the system control unit 39 controls the entire processing in the image reconstruction by controlling the preprocessing unit 34, the reconstruction auxiliary processing unit 36, and the image reconstruction unit 37, and reads the image data from the image storage unit 38. Then, the monitor included in the display unit 32 is controlled to display the image data.

  The “first data collection unit 15” and the “second data collection unit 16” described above correspond to the “data collection unit” recited in the claims, and the “preprocessing unit 34” The “reconstruction auxiliary processing unit 36” and the “image reconstruction unit 37” correspond to the “back projection processing unit” and the “image composition processing unit”.

  Here, the X-ray CT apparatus according to the present embodiment is provided with the couchtop rotating unit 12 in which the X-ray tube 13 and the X-ray detector 14 face each other as described above. The X-ray tube 13 is rotated around the subject P lying on the X-ray, the X-ray tube 13 irradiates the subject P from multiple directions, and the X-ray intensity distribution data is detected by the X-ray detector 14. The main feature is that an image is reconstructed in the console device 30 as an outline, and a three-dimensional image can be immediately reconstructed and stored as three-dimensional image data.

  This main feature will be described with reference to FIGS. FIG. 2 is a diagram for explaining the concept of image reconstruction in the present embodiment. FIG. 3 illustrates data transmission between the first acquisition unit, the second acquisition unit, the preprocessing unit, and the projection data storage unit. FIG. 4 is a diagram for explaining data transmission among the preprocessing unit, the projection data storage unit, and the reconstruction auxiliary processing unit, and FIG. FIG. 6 is a diagram for explaining the data transmission to the image reconstruction unit, FIG. 6 is a diagram for explaining the image reconstruction unit, and FIG. 7 is a diagram from the image reconstruction unit to the reconstruction auxiliary processing unit. FIG. 8 is a diagram for explaining data transmission, and FIG. 8 is a diagram for explaining data transmission from the reconstruction auxiliary processing unit to the image storage unit.

  As shown in FIG. 2, the X-ray CT apparatus in the present embodiment irradiates the subject P with X-rays generated from the X-ray tube 13 with a fan angle and a cone angle from multiple directions, X-ray intensity distribution data is detected by the X-ray detector 14.

  In the conventional image reconstruction, X-ray intensity distribution data detected by the detection elements arranged along the body axis direction is collected in units of columns, and a plurality of tomographic images are obtained from each of the X-ray intensity distribution data in units of columns. A three-dimensional image is reconstructed from a plurality of tomographic images.

  However, the image reconstruction performed by the X-ray CT apparatus in this embodiment is the X-ray intensity detected by the X-ray detector 14 which is a two-dimensional array detector having X-ray detection elements arranged in multiple rows such as 256 rows. As shown in FIG. 2, the distribution data is collected for each X-ray irradiation direction, that is, in units of views, thereby reconstructing the three-dimensional images in units of views and combining them. A three-dimensional image based on all X-ray intensity distribution data detected while the gantry rotating unit 12 rotates around the subject P is reconstructed.

  For example, in the case of conventional scanning, the X-ray CT apparatus according to the present embodiment collects X-ray intensity distribution data for at least 900 views. However, X-ray intensity distribution data for 900 views is collected for each view. Collected in a lump, reconstructs 900 three-dimensional images for each view, synthesizes them, and the number of 900 views detected while the gantry rotating unit 12 makes one rotation around the subject P A three-dimensional image based on the X-ray intensity distribution data is reconstructed.

  In order to realize the image reconstruction based on the above-described concept, the X-ray CT apparatus in the present embodiment first has X-rays detected by all the detection elements of the X-ray detector 14 in the first data collection unit 15. Line intensity distribution data is collected in view units. In the following description, it is assumed that the X-ray detector 14 has X-ray detection elements (hereinafter referred to as detection elements) arranged in “n” columns.

  That is, as shown in FIG. 3, the first data collection unit 15 is equipped with an FPGA (Field Programmable Gate Array) that performs high-speed processing, and the FPGA detects X-rays detected by the X-ray detector 14. Intensity distribution data is collected in view units, and projection data is generated by performing amplification processing, A / D conversion processing, and the like on the collected X-ray intensity distribution data in view units. Then, the FPGA mounted on the first data collection unit 15 collects the generated projection data in a unit of view by the high-speed data transmission path via the high-speed transmission I / F included in itself. The data is transmitted to the collection unit 16. At this time, the first data collection unit 15 converts the data for the “n” column into the data corresponding to the detection data in the “# 0 to # n / 2-1” column and “# n / 2 to ##”. The data corresponding to the detection data in the “n−1” column and the data corresponding to the “n / 2” column are divided into two, and transmitted to the second data collection unit 16 through two high-speed data transmission paths.

  As shown in FIG. 3, the second data collection unit 16 is equipped with an FPGA having the same processing capability as the FPGA installed in the first data collection unit 15, and this FPGA has the same high-speed transmission I / F. Provided. Further, the second data collection unit 16 includes two DDRs (Double Data Rates) that are large-capacity external memories for storing data before and after the processing of the FPGA, and these two DDRs are connected to the FPGA. The

  The FPGA mounted on the second data collection unit 16 receives projection data in view units from the first data collection unit 15 via the high-speed transmission I / F included in the FPGA, and receives the projection data in view units. The data is divided into two DDRs and stored, and adjustment is performed so that projection data in units of views is transmitted collectively to the preprocessing unit 34 via another high-speed transmission I / F included in the DDR.

  Here, the two DDRs shown in FIG. 3 include projection data corresponding to the detection data in the “# 0 to # n / 2-1” column and detection data in the “# n / 2 to # n−1” column. The FPGA mounted in the second data collection unit 16 adjusts the reading speed of data from the two DDRs as the data buffer, and the projection data in view units are stored in the previous data. It adjusts so that it may transmit to the process part 34 collectively.

  In the present embodiment, the FPGA mounted on the second data collection unit 16 transmits the processed X-ray intensity distribution data with “m” view as one unit to the preprocessing unit 34 in a batch. Adjust to be.

  As shown in FIG. 3, the pre-processing unit 34 is equipped with four CPUs, and these CPUs are each provided with a high-speed transmission I / F. These high-speed transmission I / Fs are the same as those included in the FPGA mounted in the first data collection unit 15 and the second data collection unit 16, and the four CPUs mounted in the preprocessing unit 34 are , Each of the projection data having the “m” view as one unit is received from the second data collection unit 16 via the high-speed transmission I / F included in each.

  That is, as shown in FIG. 3, each of the four CPUs mounted on the preprocessing unit 34 includes “# 0 to # m−1” views, “#m to # 2m−1” among the projection data of 900 views. “M” view, “# 2m to # 3m−1” view, “# 3m to # 4m−1” view, etc., respectively, and logarithmic conversion processing, offset correction, sensitivity correction Correction processing such as beam hardening correction is performed.

  Then, as shown in FIG. 3, each of the four CPUs mounted on the preprocessing unit 34 has the CPU-RAID transmission I / F provided with the projection data that has been corrected for each of the generated “m” views. Are stored in each of four RAID (Redundant Array of Inexpensive Disks) mounted in the projection data storage unit 35 by a general-purpose data transmission path (for example, fiber channel).

  Subsequently, as shown in FIG. 4, each of the four CPUs mounted in the preprocessing unit 34 has corrected each stored “m” view from each of the four RAIDs mounted in the projection data storage unit 35. Are transmitted to the four CPUs mounted on the reconstruction auxiliary processing unit 36 via a general-purpose data transmission path (for example, InfiniBand) via the inter-CPU transmission I / F.

  After that, as shown in FIG. 4, the four CPUs mounted on the reconstruction auxiliary processing unit 36 are respectively connected to the four CPUs mounted on the preprocessing unit 34 via the inter-CPU transmission I / F. The projection data that has been corrected for each of the “m” views is received, and preprocessing (convolution processing) for image reconstruction is performed.

  As shown in FIG. 5, each of the four CPUs mounted on the reconstruction auxiliary processing unit 36 converts the projection data of each “m” view that has undergone preprocessing for image reconstruction, to an I / F for high-speed transmission. Then, the data is transmitted to the high-speed transmission I / F in the image reconstruction unit 37 through the high-speed data transmission path. The high-speed transmission I / F of each of the four CPUs mounted in the reconstruction auxiliary processing unit 36 and the high-speed transmission I / F in the image reconstruction unit 37 are the first data collection unit 15, This is the same as the high-speed transmission I / F provided in the second data collection unit 16 and the preprocessing unit 34. The high-speed data transmission path used for data transmission between the reconstruction auxiliary processing unit 36 and the image reconstruction unit 37 is data transmission between the first data collection unit 15 and the second data collection unit 16. And, it is the same as the high-speed data transmission path used for data transmission between the second data collection unit 16 and the preprocessing unit 34. In the following, projection data that has been subjected to correction processing and convolution processing is simply referred to as processed projection data.

  As shown in FIG. 5, the image reconstruction unit 37 includes a plurality of FPGA substrates on which a plurality of FPGAs described in the first data collection unit 15 and the second data collection unit 16 are arranged, and the plurality of FPGA substrates. Thus, a three-dimensional image as a partial image for a plurality of views is generated from the processed projection data for a plurality of views. The image reconstruction unit 37 has a plurality of DDRs as a storage unit (not shown) for storing three-dimensional volume data, and the plurality of FPGA boards mounted on the image reconstruction unit 37 are The three-dimensional volume data stored in the storage unit is subjected to back projection processing collectively using processed projection data for a plurality of views, and partial images for a plurality of views are generated. The plurality of FPGA boards mounted on the image reconstruction unit 37 repeatedly execute this backprojection process on the processed projection data for a plurality of views. Here, the image reconstruction unit 37 collectively back-projects the processed projection data for a plurality of views in units of cross sections having the same weighting to generate a three-dimensional image as a partial image.

  For example, in order to reconstruct a three-dimensional image composed of “512 × 512 × 512” pixels, the processed projection data in units of views that are back-projected to each pixel of “512 × 512 × 512” is used. It is necessary to perform interpolation processing by weighting each.

  In the conventional image reconstruction, projection data in units of columns is read, and tomographic images on the XY plane are reconstructed along the body axis direction of the subject P, that is, the Z-axis direction. In this case, as shown in FIG. 6, the weighting for the data back-projected on the XY plane at the same Z coordinate is different for all “512 × 512” pixels, and the weighting is changed every time the Z coordinate changes. It was necessary to read out data, perform interpolation processing, and perform back projection processing.

  However, in the image reconstruction of the present embodiment, the tomographic image is not reconstructed, and all the projection data for a plurality of views are read. Thus, it is possible to generate a three-dimensional image as a partial image for a plurality of views including “512 × 512 × 512” pixels.

  At that time, as shown in FIG. 6, “the weighting for the data backprojected on the YZ plane at the same X coordinate is the same” and “the data backprojected on the XZ plane at the same Y coordinate” By utilizing the fact that the weighting is the same, reconstruction of a three-dimensional image can be speeded up. That is, once the weighting data on the YZ plane or the XZ plane is read out, “512 tomographic images on all YZ planes” or “512 tomographic images on all XZ planes” are weighted together. By performing interpolation processing and backprojecting, three-dimensional images as partial images for a plurality of views can be collectively generated at a high speed, and three-dimensional images can be reconstructed at a high speed.

  Then, the image reconstruction unit 37 synthesizes three-dimensional images as partial images corresponding to 900 views generated by backprojecting collectively in units of cross-sections having the same weighting, to obtain 900 views. A three-dimensional image based on all the X-ray intensity distribution data for several minutes is reconstructed. The image reconstruction unit 37 sequentially stores the generated partial images in a plurality of DDRs included in the image reconstruction unit 37, and sequentially reads out the partial images from the plurality of DDRs to synthesize the partial images.

  Subsequently, as shown in FIG. 7, the image reconstruction unit 37 is reconstructed by a general-purpose data transmission path (for example, PCI express) through the image transmission I / F. The image is transmitted to the reconstruction auxiliary processing unit 36.

  Thereafter, each of the four CPUs mounted on the reconstruction auxiliary processing unit 36 receives the three-dimensional image reconstructed from the image reconstruction unit 37 via the image transmission I / F, as shown in FIG. The image is received, and an artifact correction process or an image process is performed in accordance with an operator instruction.

  Then, as shown in FIG. 8, each of the four CPUs mounted on the reconstruction auxiliary processing unit 36 transmits the post-processed image data to the image storage unit 38 via the image transmission I / F. The image storage unit 38 stores the received image data. The image data stored in the image storage unit 38 is displayed on the display unit 32 according to control by the system control unit 39.

  Here, data transmission in “first data collection unit 15 to second data collection unit 16”, “second data collection unit 16 to preprocessing unit 34”, and “reconstruction auxiliary processing unit 36 to image reconstruction unit 37”. For example, a high-speed data transmission path having a transmission rate of 1 GB / sec is used. Furthermore, in data transmission using a high-speed data transmission path, a function for transmitting and receiving data retransmission processing corresponding to a data transmission error and time adjustment processing for transmitting data in units of views in a batch Performed between blocks.

  For this reason, the X-ray CT apparatus according to the present embodiment can process the X-ray intensity distribution data in view units and the projection data in view units at once, and can also read the weight data once. 3D images (partial images) can be synthesized, and as described above, the 3D images can be immediately reconstructed and stored as 3D image data.

  Next, a processing flow of the X-ray CT apparatus in the present embodiment will be described with reference to FIG. FIG. 9 is a diagram for explaining processing of the X-ray CT apparatus in the present embodiment.

  As shown in FIG. 9, the X-ray CT apparatus according to the present embodiment starts imaging when setting information such as imaging conditions is input from the operator via the input unit 31 (Yes in step S901). The one data collection unit 15 generates projection data in view units from the X-ray intensity distribution data in view units (step S902). That is, the first data collection unit 15 collects the X-ray intensity distribution data detected by the X-ray detector 14 in view units, performs amplification processing, A / D conversion processing, and the like to generate projection data. Here, the second data collection unit 16 collectively receives and buffers projection data from the first data collection unit 15 in view units by the high-speed data transmission path, and performs pre-processing by the high-speed data transmission path. The projection data for each view is transmitted to the unit 34.

  Then, the preprocessing unit 34 performs a correction process on the received projection data in units of views (step S903), and sends the projection data that has been corrected in units of views to the reconstruction auxiliary processing unit 36 through a high-speed data transmission path. Send.

  After that, the reconstruction auxiliary processing unit 36 receives the corrected projection data in view units from the preprocessing unit 34 through the high-speed data transfer path, performs preprocessing for reconstruction (step S904), and performs reconstruction. The pre-processed projection unit projection data for configuration is transmitted to the image reconstruction unit 37 via the high-speed data transfer path.

  Subsequently, the image reconstruction unit 37 generates a three-dimensional image as a partial image for a plurality of views from the projection data for a plurality of preprocessed views for reconstruction, and synthesizes them. Thus, a three-dimensional image based on the X-ray intensity distribution data of all views is reconstructed (step S905).

  Then, the reconstruction auxiliary processing unit 36 performs post-processing of the three-dimensional image based on the X-ray intensity distribution data of all views received from the image reconstruction unit 37 (step S906), and stores the post-processed image data as an image. The system control unit 39 reads the post-processed image data from the image storage unit 38 and controls it to be displayed on the display unit 32 (step S907), and ends the process.

  As described above, in the present embodiment, the first data collection unit 15 collects the X-ray intensity distribution data detected by the X-ray detector 14 in view units and performs amplification processing, A / D conversion processing, and the like. Projection data is generated, and the second data collection unit 16 receives and buffers projection data from the first data collection unit 15 in units of views from the first data collection unit 15 through the high-speed data transmission path, and performs a high-speed data transmission path. Thus, the projection data in view units is transmitted to the preprocessing unit 34 at once, and the preprocessing unit 34 corrects the received projection data in view units.

  Then, the reconstruction auxiliary processing unit 36 receives projection data in view units from the preprocessing unit 34 via the high-speed data transfer path, performs preprocessing for reconstruction, and performs preprocessed views for reconstruction. Unit projection data is transmitted to the image reconstruction unit 37 via a high-speed data transfer path, and the image reconstruction unit 37 collectively projects the projection data for a plurality of views in units of cross sections having the same weight. Since the three-dimensional image is reconstructed from the generated partial images for a plurality of views, the reconstruction auxiliary processing unit 36 performs post-processing of the three-dimensional image received from the image reconstruction unit 37 and stores it in the image storage unit 38. The X-ray intensity distribution data in view units and the projection data in view units can be processed at once, and a three-dimensional image (partial image) in view units can be generated by reading weighted data once. It can be, it is possible to reconstruct a three-dimensional image immediately.

  In this embodiment, the case where the high-speed data transmission path is used in a part of the data transmission between the functional blocks in the X-ray CT apparatus has been described. However, the present invention is not limited to this, for example, A high-speed data transmission path may be used for all data transmission between functional blocks.

  In this embodiment, the case where a three-dimensional image is reconstructed from data acquired by conventional scanning has been described. However, the present invention is not limited to this, and is acquired by continuous conventional scanning or helical scanning. It may be a case where a three-dimensional image is reconstructed from the processed data.

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

  Further, each component of each illustrated apparatus is functionally conceptual, and does not necessarily need to be physically configured as illustrated. In other words, the specific form of distribution / integration of each device is not limited to that shown in the figure, and all or a part thereof may be functionally or physically distributed or arbitrarily distributed in arbitrary units according to various loads or usage conditions. Can be integrated and configured. Further, all or any part of each processing function performed in each device may be realized by a CPU and a program analyzed and executed by the CPU, or may be realized as hardware by wired logic.

  As described above, the X-ray CT apparatus according to the present invention is useful when reconstructing an image based on projection data indicating the intensity distribution of X-rays that have passed through the subject. It is suitable for reconstructing and storing as three-dimensional image data.

It is a figure for demonstrating the structure of the X-ray CT apparatus in a present Example. It is a figure for demonstrating the concept of the image reconstruction in a present Example. It is a figure for demonstrating the data transmission between a 1st collection part, a 2nd collection part, a pre-processing part, and a projection data storage part. It is a figure for demonstrating the data transmission between a pre-processing part, a projection data storage part, and the reconstruction assistance process part. It is a figure for demonstrating the data transmission from a reconstruction assistance process part to an image reconstruction part. It is a figure for demonstrating an image reconstruction part. It is a figure for demonstrating the data transmission from an image reconstruction part to the reconstruction assistance process part. It is a figure for demonstrating the data transmission from a reconstruction assistance process part to an image memory | storage part. It is a figure for demonstrating the process of the X-ray CT apparatus in a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Mount apparatus 11 Mount fixing part 12 Mount rotation part 13 X-ray tube 14 X-ray detector 15 1st data collection part 16 2nd data collection part 17 High voltage generation part 18 Mount drive part 20 Sleeper apparatus 21 Sleeper drive part 22 Top Board 30 Console device 31 Input unit 32 Display unit 33 Scan control unit 34 Pre-processing unit 35 Projection data storage unit 36 Reconstruction auxiliary processing unit 37 Image reconstruction unit 38 Image storage unit 39 System control unit

Claims (4)

An X-ray CT apparatus for reconstructing an image based on projection data indicating an intensity distribution of X-rays transmitted through a subject,
An X-ray detector in which a plurality of detection element arrays each including X-ray detection elements for a plurality of channels are arranged;
A data collecting means for rotating the X-ray tube for exposing X-rays and the X-ray detector around the subject and collecting projection data for each X-ray irradiation direction;
Storage means for storing three-dimensional volume data;
Projection data for a plurality of channels and a plurality of columns corresponding to the X-ray irradiation direction collected by the data collection unit is stored on the three-dimensional volume data stored in the storage unit for each cross section having the same weight used for convolution. Back projection processing means configured to perform back projection processing and repeat this back projection processing for each X-ray irradiation direction;
An X-ray CT apparatus comprising: The projection data acquired by the previous SL data acquisition unit, a data distribution means for distributing divided by X-ray irradiation direction units,
A plurality of preprocessing means for performing correction processing on the projection data sent from the data distribution means via the data transmission means ;
Synthesizes the backprojection data processed by the pre Kigyaku projection processing unit, an image combining processing means for generating a 3-dimensional image data,
Further comprising
The backprojection processing means has a plurality of backprojection processing means for performing backprojection processing for each cross section having the same weight used for convolution on the projection data sent from the preprocessing means via the data transmission means. The X-ray CT apparatus according to claim 1 .   The X-ray CT apparatus according to claim 2, wherein the data transmission means is a plurality of physically separated transmission lines. Projection data storage means for storing the projection data corrected by the pre-processing means,
The X-ray CT apparatus according to claim 3, wherein the back projection processing unit performs back projection processing on the projection data after correction processing stored in the projection data storage unit.

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