JP2008000163A - X-ray ct apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray CT apparatus obtaining a set of CT images at the same time of day at different image positions for a plurality of times of day at constant time intervals. <P>SOLUTION: The CT image c at an image position zs at a time ts of day is produced by the interpolation based on the CT image a at the image position zs at a time of day before the time ts of day and the CT image b at the image position zs at a time of day after the time ts of day. By repeating these processes, a set of CT images at image positions zs-zf at the same time of day for a plurality of times of day at the constant time intervals are obtained. According to this invention, the set of CT images at the different image positions and at the same time of day for a plurality of times of day at the constant time intervals, the set of CT images necessary for the perfusion CT, can be obtained. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an X-ray CT (Computed Tomography) apparatus, and more specifically, a plurality of times corresponding to the same time and a plurality of times at fixed time intervals of each CT image at a plurality of image positions within a predetermined z-direction range. The present invention relates to an X-ray CT apparatus capable of obtaining a set of

Conventionally, Perfusion CT using an X-ray CT apparatus using a multi-detector is known (for example, see Non-Patent Document 1).
Takahashi, Arakawa, “All about Multidetector Helical CT” February 1, 2000, 1st edition, pages 24-25

In Perfusion CT, a set of CT images corresponding to the same time and at a plurality of image positions within a predetermined z-direction range for a plurality of times at fixed time intervals, like a CT image set in Cine scan. Is needed.
However, in the helical shuttle scan, projection data is collected while continuously performing rotation and linear movement. Therefore, the obtained CT images correspond to different times and have different image positions. Become.
In the Axial Shuttle scan, projection data is collected while only rotating at a certain scan position, then a relative straight line is moved to the next scan position, and only rotation is performed at that scan position. Since the projection data is collected by repeatedly collecting the projection data, the obtained CT images become CT images corresponding to the scan times of the respective scan positions and having different image positions.
Accordingly, an object of the present invention is to obtain an X-ray that can obtain a set of a plurality of times at fixed time intervals for each CT image at a plurality of image positions corresponding to the same time and within a predetermined z-direction range. It is to provide a CT apparatus.

In a first aspect, the present invention provides an X-ray tube, a multi-detector, a rotating means for relatively rotating at least one of the X-ray tube and the multi-detector around an imaging target, and the X-ray Linear movement means for moving at least one of the tube and the multi-detector relative to the object to be imaged, and continuously performing the relative rotation and the relative linear movement from the relative linear movement start point to the relative linear movement end point. A scanning unit that collects projection data while executing, and a same-time image creation unit that creates a plurality of CT images corresponding to the same time and different image positions using the collected projection data An X-ray CT apparatus is provided.
In the above configuration, “relative rotation” means that the imaging target is placed between the X-ray tube and the multi-detector, and at least one of the X-ray tube and the multi-detector is moved around the imaging target without rotating the imaging target. When rotating, when rotating the imaging target without rotating the X-ray tube and the multi-detector, When rotating the imaging target and rotating at least one of the X-ray tube and the multi-detector around the imaging target It means to include.
Further, in the above configuration, “relative linear movement” means a table on which an imaging target is placed without linearly moving the X-ray tube and the multi-detector while the imaging target is placed between the X-ray tube and the multi-detector. ) Is moved linearly, the X-ray tube and the multi-detector are moved linearly without moving the imaging target (the table on which the image is placed), and the X-ray tube This includes the case where the multi-detector is linearly moved in the reverse direction.
In the X-ray CT apparatus according to the first aspect, a plurality of CT images corresponding to the same time and having different image positions are created based on projection data collected by a helical scan (including a helical shuttle scan). If it is performed for a plurality of times at regular time intervals, a set of the CT images corresponding to the same time and at a plurality of image positions within a predetermined z-direction range for a plurality of times at regular time intervals, that is, A set of CT images required for Perfusion CT can be obtained.
A method of creating a plurality of CT images corresponding to the same time and having different image positions from the collected projection data can be performed by interpolation at the CT image level or interpolation at the projection data level.

In a second aspect, the present invention provides the X-ray CT apparatus according to the first aspect, wherein the same time image creating means generates a plurality of CT images corresponding to different times and having different image positions. X-ray CT apparatus comprising: means for converting a plurality of CT images corresponding to different times and having different image positions into a plurality of CT images corresponding to the same time and having different image positions I will provide a.
In the X-ray CT apparatus according to the second aspect, a plurality of CT images corresponding to different times by normal image reconstruction based on projection data collected by helical scan (including helical shuttle scan) and different image positions are obtained. Generate. Then, a plurality of CT images corresponding to the different times and having different image positions are converted into a plurality of CT images corresponding to the same time and having different image positions. If this is performed for a plurality of times at fixed time intervals, a set of the CT images corresponding to the same time and at a plurality of image positions within a predetermined z-direction range for a plurality of times at fixed time intervals, That is, a set of CT images necessary for Perfusion CT can be obtained.

In a third aspect, the present invention provides the X-ray CT apparatus according to the second aspect, wherein the image conversion means performs an interpolation operation on a time axis.
In the X-ray CT apparatus according to the third aspect, a plurality of CT images corresponding to different times by normal image reconstruction based on projection data collected by helical scan (including helical shuttle scan) and having different image positions are obtained. Generate. Then, an interpolation operation with respect to the time axis is performed on a plurality of CT images corresponding to the different times and different image positions, and converted into a plurality of CT images corresponding to the same time and different image positions. If this is performed for a plurality of times at fixed time intervals, a set of the CT images corresponding to the same time and at a plurality of image positions within a predetermined z-direction range for a plurality of times at fixed time intervals, That is, a set of CT images necessary for Perfusion CT can be obtained.

In a fourth aspect, the present invention provides the X-ray CT apparatus according to any one of the first to third aspects, wherein the same-time image creating means is configured at each time at a plurality of times at fixed time intervals. Provided is an X-ray CT apparatus characterized by creating a plurality of CT images corresponding to different image positions.
In the X-ray CT apparatus according to the fourth aspect, a plurality of CT images corresponding to the same time and having different image positions are created based on projection data collected by a helical scan (including a helical shuttle scan), and this is fixed. Since it is performed for a plurality of times for each time interval, a set for a plurality of times for each constant time interval of each CT image corresponding to the same time and at a plurality of image positions within a predetermined z-direction range, that is, Perfusion A set of CT images required for CT can be obtained.

In a fifth aspect, the present invention provides an X-ray tube, a multi-detector, a rotating means for relatively rotating at least one of the X-ray tube and the multi-detector around an imaging target, and the X-ray Linear movement means for moving at least one of the tube and the multi-detector relative to the object to be imaged, and collecting projection data while executing the relative rotation at the relative linear movement start point, and then the next scan position Scanning means that repeats the relative linear movement to collect the projection data while executing the relative rotation to the end point of the relative linear movement, and a plurality of image positions corresponding to the same time using the collected projection data and having different image positions There is provided an X-ray CT apparatus comprising an identical time image creation means for creating a CT image.
In the X-ray CT apparatus according to the fifth aspect, a plurality of CT images corresponding to the same time and having different image positions based on projection data collected by repeating an axial scan (including an axial shuttle scan) at different scan positions. Therefore, if this is performed for a plurality of times at fixed time intervals, a plurality of CT images corresponding to the same time at a plurality of image positions within a predetermined z-direction range at a plurality of fixed time intervals. A set of time, that is, a set of CT images necessary for Perfusion CT can be obtained.
A method of creating a plurality of CT images corresponding to the same time and having different image positions from the collected projection data can be performed by interpolation at the CT image level or interpolation at the projection data level.

In a sixth aspect, the present invention provides the X-ray CT apparatus according to the fifth aspect, wherein the same-time image creating means generates a plurality of CT images corresponding to scan times at different scan positions and having different image positions. An image reconstructing means to be generated, and an image converting means for converting a plurality of CT images corresponding to the scan time at the respective scan positions and having different image positions into a plurality of CT images corresponding to the same time and having different image positions. An X-ray CT apparatus is provided.
In the X-ray CT apparatus according to the sixth aspect, the scan time at each scan position is obtained by normal image reconstruction based on the projection data collected by repeating the axial scan at different scan positions (including the axial shuttle scan). A plurality of CT images corresponding to different image positions are generated. Then, a plurality of CT images corresponding to the scan times at the different scan positions and having different image positions are converted into a plurality of CT images corresponding to the same time and having different image positions. If this is performed for a plurality of times at fixed time intervals, a set of the CT images corresponding to the same time and at a plurality of image positions within a predetermined z-direction range for a plurality of times at fixed time intervals, That is, a set of CT images necessary for Perfusion CT can be obtained.

In a seventh aspect, the present invention provides the X-ray CT apparatus according to the sixth aspect, wherein the image conversion means performs an interpolation operation on a time axis.
In the X-ray CT apparatus according to the seventh aspect, the scan time at each scan position is obtained by normal image reconstruction based on the projection data collected by repeating the axial scan at different scan positions (including the axial shuttle scan). A plurality of CT images corresponding to different image positions are generated. Then, interpolation is performed with respect to the time axis on a plurality of CT images corresponding to the scan times at these scan positions and having different image positions, and converted to a plurality of CT images corresponding to the same time and having different image positions. . If this is performed for a plurality of times at fixed time intervals, a set of the CT images corresponding to the same time and at a plurality of image positions within a predetermined z-direction range for a plurality of times at fixed time intervals, That is, a set of CT images necessary for Perfusion CT can be obtained.

In an eighth aspect, the present invention provides the X-ray CT apparatus according to any one of the fifth to seventh aspects, wherein the same-time image creating means is configured at each time at a plurality of times at a fixed time interval. Provided is an X-ray CT apparatus characterized by creating a plurality of CT images corresponding to different image positions.
In the X-ray CT apparatus according to the eighth aspect, a plurality of CT images corresponding to the same time and having different image positions based on projection data collected by repeating an axial scan (including an axial shuttle scan) at different scan positions. Since this is performed for a plurality of times at regular time intervals, a plurality of times at regular time intervals for each CT image at a plurality of image positions corresponding to the same time and within a predetermined z-direction range A set of CT images, that is, a set of CT images necessary for Perfusion CT can be obtained.

  According to the X-ray CT apparatus of the present invention, a set for a plurality of times at fixed time intervals of each CT image corresponding to the same time and at a plurality of image positions within a predetermined z-direction range, that is, Perfusion. A set of CT images required for CT can be obtained.

   Hereinafter, the present invention will be described in more detail with reference to embodiments shown in the drawings. Note that the present invention is not limited thereby.

FIG. 1 is a configuration diagram illustrating an X-ray CT apparatus 100 according to the first embodiment.
The X-ray CT apparatus 100 includes an operation console 1, a bed apparatus 10, and a scanning gantry 20.

  The operation console 1 includes an input device 2 that receives input from an operator, a central processing unit 3 that executes image reconstruction processing, a data collection buffer 5 that collects projection data acquired by the scanning gantry 20, and a projection data. A CRT 6 that displays the reconstructed CT image and a storage device 7 that stores programs, data, and X-ray CT images are provided.

  The bed apparatus 10 includes a table 12 on which an object to be imaged is placed and put into and out of a bore (cavity) of the scanning gantry 20. The table 12 is moved up and down and linearly moved by a motor built in the bed apparatus 10.

  The scanning gantry 20 rotates to control the X-ray tube 21, X-ray controller 22, collimator 23, multi-detector 24, DAS (Data Acquisition System) 25, X-ray controller 22, collimator 23, and DAS 25. A side controller 26, a control controller 29 for exchanging control signals and the like with the operation console 1 and the imaging table 10, and a slip ring 30 are provided.

FIG. 2 is an exemplary diagram showing a time and an image position corresponding to each CT image obtained by performing normal image reconstruction processing on the projection data collected by the helical shuttle scan.
In this example, CT images at a plurality of image positions within the z-direction range from the position zs to the position zf are obtained, but their corresponding times are all different. Here, δ is the distance interval in the z direction of each CT image, and α is the time interval in the time axis direction of each CT image.

FIG. 3 is a flowchart showing image conversion processing.
In step A1, the operator sets a start time ts (see FIG. 4), which is the first time of the CT image set, and a time interval τ (see FIG. 6) between adjacent times.
In step A2, the time counter t is initialized to the first time ts.

  In step A3, the image position counter z is initialized to the start image position zs.

In step A4, a CT image at the image position z at time t is created based on the CT images at the image position z at times before and after time t.
For example, as shown in FIG. 4, an image at time ts is obtained by interpolation from a CT image a at image position zs at a time before time ts and a CT image b at image position zs at a time after time ts. A CT image c at position zs is created.

  In step A5, if the image position counter z has not reached the end image position zf (see FIG. 4), the process proceeds to step A6, and if it has reached, the process proceeds to step A7.

In step A6, the image position counter z is incremented by the image position interval δ (see FIG. 4). Then, the process returns to step A4.
Then, in the returned step A4, for example, as shown in FIG. 5, from the CT image d at the image position zs + δ at the time before the time ts and the CT image e at the image position zs + δ at the time after the time ts, A CT image f at the image position zs + δ at time ts is created by interpolation.

  In step A7, if the time counter t has not reached the end time tf (see FIG. 6), the process proceeds to step A8, and if it has reached, the process is terminated.

In step A8, the time counter t is incremented by the time interval τ. And it returns to step A3.
Then, after returning to Step A3, for example, as shown in FIG. 6, CT images of the image position zs to the image position zf at time ts + τ are created.
Thus, as shown in FIG. 6, a set of a plurality of times ts to tf for each fixed time interval τ of each CT image corresponding to the same time and image positions zs to zf can be obtained.

  According to the X-ray CT apparatus 100 of the first embodiment, a set of CT images necessary for Perfusion CT can be obtained.

FIG. 7 is an exemplary diagram showing a time and an image position corresponding to each CT image obtained by performing normal image reconstruction processing on the projection data collected by the axial shuttle scan.
In this example, a time corresponding to a CT image at a plurality of image positions within the z-direction range from the position zs to the position zm, and a CT image at a plurality of image positions within the z-direction range from the position zn to the position zf. The time corresponding to is different. Α is a time interval between scan times at each scan position.

  As shown in FIG. 8, if the image conversion processing shown in FIG. 3 is performed based on each CT image shown in FIG. 7, a certain time of each CT image corresponding to the same time and at the image position zs to the image position zf. A set for a plurality of times ts to tf for each interval τ can be obtained.

  In the first and second embodiments, the interpolation at the CT image level is used. However, even if the interpolation at the projection data level is used, a plurality of CT images corresponding to the same time and having different image positions are created. I can do it.

  The X-ray CT apparatus of the present invention can be used for, for example, Perfusion CT.

1 is a configuration diagram illustrating an X-ray CT apparatus according to Embodiment 1. FIG. It is explanatory drawing which shows the time and image position corresponding to CT image produced | generated by performing normal image reconstruction processing to the projection data collected by the helical shuttle scan. FIG. 3 is a flowchart illustrating image conversion processing according to the first embodiment. FIG. 6 is an explanatory diagram illustrating a time and an image position corresponding to a CT image c created by the image conversion process according to the first embodiment. FIG. 6 is an explanatory diagram illustrating a time and an image position corresponding to a CT image f created by the image conversion process according to the first embodiment. FIG. 6 is an explanatory diagram illustrating a time and an image position corresponding to a CT image created by the image conversion process according to the first embodiment. It is explanatory drawing which shows the time and image position corresponding to CT image produced | generated by performing normal image reconstruction processing to the projection data collected by the axial shuttle scan. FIG. 9 is an explanatory diagram illustrating a time and an image position corresponding to a CT image created by an image conversion process according to a second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Operation console 3 Central processing unit 5 Data collection buffer 10 Bed apparatus 12 Table 20 Scanning gantry 21 X-ray tube 24 Multi-detector 26 Rotation side controller 100 X-ray CT apparatus

Claims (8)

  An X-ray tube, a multi-detector, a rotating means for relatively rotating at least one of the X-ray tube and the multi-detector around an object to be imaged, and at least one of the X-ray tube and the multi-detector. A linear moving means for moving the object relative to the photographing object, and a scanning means for collecting projection data while continuously executing the relative rotation and the relative linear movement from the relative linear movement start point to the relative linear movement end point. And an identical time image creation means for creating a plurality of CT images corresponding to the same time and having different image positions using the collected projection data.   2. The X-ray CT apparatus according to claim 1, wherein the same time image generating unit corresponds to the image reconstruction unit that generates a plurality of CT images corresponding to different times and different image positions, and corresponds to the different times. An X-ray CT apparatus comprising image conversion means for converting a plurality of CT images having different image positions into a plurality of CT images corresponding to the same time and having different image positions.   The X-ray CT apparatus according to claim 2, wherein the image conversion unit performs an interpolation operation on a time axis.   The X-ray CT apparatus according to any one of claims 1 to 3, wherein the same-time image creating means includes a plurality of CTs corresponding to each time and having different image positions for each of a plurality of times at a fixed time interval. An X-ray CT apparatus characterized by creating an image.   An X-ray tube, a multi-detector, a rotating means for relatively rotating at least one of the X-ray tube and the multi-detector around an object to be imaged, and at least one of the X-ray tube and the multi-detector. A linear moving means for moving the image relative to the object to be imaged, and collecting the projection data while executing the relative rotation at the starting point of the relative linear movement, and then moving the relative straight line to the next scan position to perform the relative rotation. A scanning unit that repeatedly collects projection data while executing it until a relative linear movement end point, and a same-time image creation unit that creates a plurality of CT images corresponding to the same time and different image positions using the collected projection data An X-ray CT apparatus comprising:   6. The X-ray CT apparatus according to claim 5, wherein the same time image creation unit includes: an image reconstruction unit that generates a plurality of CT images corresponding to scan times at different scan positions and different image positions; An X-ray CT apparatus comprising: image conversion means for converting a plurality of CT images corresponding to a scan time at a scan position and having different image positions into a plurality of CT images corresponding to the same time and having different image positions .   The X-ray CT apparatus according to claim 6, wherein the image conversion unit performs an interpolation operation on a time axis.   8. The X-ray CT apparatus according to claim 5, wherein the same-time image creation unit includes a plurality of CTs corresponding to each time and having different image positions for each of a plurality of times at a constant time interval. An X-ray CT apparatus characterized by creating an image.

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