JP2003190144A - X-ray ct system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray CT system in which irreducibly minimum tomographic images for main scan can be acquired without increasing the number of times of exposure. <P>SOLUTION: A reconstruction range designating part 22 for main scan is provided for designating a desired range in the imaging range of an examinee M as an image reconstruction range for main scan so that an image for main scan can be reconstructed just within the designated range and only a tomographic image for main scan within the designated range can be generated. Besides, a range to reconstruct the image for main scan is designated to a tomographic image for display really imaged and applied with simplified image reconstructing processing and only by performing image reconstructing processing for main scan within the designated range, the tomographic image for main scan within the designated range can be acquired. Further, since it is not necessary to perform re-exposure, the irreducibly minimum tomographic image for main scan can be generated without increasing the number of times of exposure. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray CT apparatus for picking up an image of a subject to obtain a production tomographic image of a region of interest of the subject, and is particularly required without increasing the number of exposures. The present invention relates to a technique for obtaining a minimum production tomographic image.

[0002]

2. Description of the Related Art In a conventional X-ray CT apparatus, a production tomographic image of a subject is acquired as described below.
The “production tomographic image” here is generally referred to as a tomographic image obtained by image reconstruction, and is called so as to be distinguished from a display tomographic image described later. First, an X-ray tube that irradiates the subject with X-rays and an X-ray detector that detects X-rays that have passed through the subject are placed opposite to each other with the subject placed on the top plate interposed therebetween. Fluorescence imaging is performed to obtain a positioning fluoroscopic image obtained by fluoroscopically imaging the subject in a desired position around the body axis. Then, based on this fluoroscopic image for positioning,
Setting the imaging range for X-ray CT imaging of the region of interest of the subject,
The so-called X-ray CT imaging is positioned.

Then, the X-ray tube and the X-ray detector are scanned around the body axis of the subject in the imaging range of the subject, and X-ray is detected.
Line CT imaging is performed. During the X-ray CT imaging, the X-ray detection signal of the X-ray detector obtained at each scanning position is used to reconstruct the simplified image in order to inform the doctor or the operator of the progress of the X-ray CT imaging. The configuration processing is performed to generate a display tomographic image of the imaging range that is simplified compared to the production tomographic image, and the generated display tomographic image is displayed on the monitor in real time. Then, the X-ray detection signal of the X-ray detector at each scanning position that has already been acquired by the above-mentioned X-ray CT imaging is subjected to the production image reconstruction processing, and the production tomographic image regarding the imaging range where the subject is imaged is obtained. An image (production CT image) is generated.

Further, instead of the above-mentioned positioning by the fluoroscopic image for positioning, there is a case where the positioning is performed by using a light projector. In this case, the range to be imaged (imaging range) is estimated based on the external characteristics of the subject. Then, the X-ray CT imaging is performed for the set imaging range.

In addition, for the purpose of bringing the region of interest closer to the center of the tomographic image for production, positioning fluoroscopic images from a plurality of directions may be generated and used for setting the imaging range.

[0006]

However, the conventional example having such a structure has the following problems. That is, in the X-ray CT apparatus, the production tomographic images (production CT images) of the region of interest of the subject are increased more than necessary, and storage of the produced production tomographic images and film printing are burdens. There is a problem.

Specifically, as a recent X-ray CT apparatus,
A multi-slice type device, which can obtain a plurality of slice data in one scan with respect to a subject, has appeared, and such a multi-slice type X-ray C
In the case of the T-apparatus, a plurality of slice data can be obtained in a short time, so that the number of production tomographic images generated is remarkably increased. In addition, when using a fluoroscopic image for positioning or using a projector, it is often the case that the imaging range is set wide so that the region of interest is not removed. Will increase. Generally, in the medical field, X-ray CT
The production tomographic image once acquired is not easily erased so that the production tomographic image obtained by imaging is not accidentally erased. In this way, the number of tomographic images to be generated is dramatically increased, and storage of the generated tomographic images for production and film printing are burdened.

Further, from the viewpoint of image observation, there may be a demand for centering the image of the region of interest and enlarging the region of interest. In this case, the subject is fluoroscopically imaged from a plurality of directions. Then, the fluoroscopic images for positioning viewed from a plurality of directions are respectively generated, and the imaging range is set based on the best fluoroscopic image for positioning, and thus the fluoroscopic images for positioning from a plurality of directions are set. However, there is a problem in that the number of exposures increases due to the acquisition of the

The present invention has been made in view of the above circumstances, and provides an X-ray CT apparatus capable of obtaining a minimum necessary production tomographic image without increasing the number of exposures. With the goal.

[0010]

The present invention has the following constitution in order to achieve such an object. That is, the X-ray CT apparatus according to claim 1 has: (a) an X-ray source that irradiates the subject with X-rays; and (b) the X-ray source with the subject interposed therebetween.
An X-ray detector that is arranged so as to face the radiation source and detects X-rays that have passed through the subject; and (c) scanning means that scans the X-ray source and the X-ray detector around the body axis of the subject. , (D) Simplified image reconstruction processing of the X-ray detection signal of the X-ray detector obtained at each scanning position is performed, compared with a production tomographic image in the imaging range in which the subject is imaged. The simplified reconstructing means for generating the converted display tomographic image, (e) the image displaying means for displaying the display tomographic image generated by the simplified reconstructing means, and (f) the image according to the input instruction. A range designating unit for designating a production image reconstruction range for the display tomographic image displayed on the display unit, and (g) an acquired image corresponding to the production image reconstruction range designated by the range designating unit. The X-ray detection signal of the X-ray detector at each scanning position of the Conversion treatment to, characterized in that it comprises a production for reconstructing means for generating a tomographic image for production for production for image reconstruction range.

(Operation / effect) X-ray CT according to claim 1
According to the apparatus, a desired range of the imaging range for X-ray CT imaging of the subject can be designated as the production image reconstruction range. Therefore, only the designated range of the imaging range of the subject can be used for the production image reconstruction. It can be configured, and only the production tomographic image in the designated range can be generated. In other words, the image reconstruction outside the specified range, that is, the production image reconstruction for generating the unnecessary production tomographic image is not executed, and the unnecessary production tomographic image may increase. Since it does not exist, the burden of storing the acquired production tomographic image and film printing does not increase. In addition, the range for reconstructing the production image is specified with respect to the display tomographic image that has been actually captured and subjected to the simplified image reconstruction processing,
By only performing the production image reconstruction processing for the specified range, it is possible to obtain the production tomographic image of the specified range.
Since it is not necessary to perform re-exposure, it is possible to generate the minimum necessary production tomographic image without increasing the number of times of exposure.

The "display tomographic image" in the present specification means a tomographic image which is simplified as compared with the production tomographic image, and is a tomographic image which is rougher than the dense production tomographic image. Is. Further, the "simple image reconstruction process" in the present specification is an image reconstruction process which is simplified as compared with the production image reconstruction process, and is a rough display compared with a dense production tomographic image. It is an image reconstruction process for generating a tomographic image for use.

The X-ray CT apparatus according to claim 2 is
The X-ray CT apparatus according to claim 1, wherein the image display means displays a plurality of display tomographic images in the imaging range in parallel in the imaging order, and the range designating means:
It is characterized in that a production image reconstruction range is designated for a plurality of display tomographic images displayed on the image display means.

(Operation / effect) X-ray CT according to claim 2
According to the apparatus, since the production image reconstruction range is specified for the plurality of display tomographic images in the imaging range displayed in parallel in the imaging order, it is easy to specify the production image reconstruction range. It is possible to accurately specify the required production image reconstruction range.

The X-ray CT apparatus according to claim 3 is
The X-ray CT apparatus according to claim 1 or 2, wherein the simplification reconstructing unit is interlocked with an imaging speed for imaging the subject to generate a tomographic image for display at the imaged position. The image display means displays the tomographic image for display generated by the reconstructing means for simplification in real time so as to be linked to the imaging speed.

(Operation / effect) X-ray CT according to claim 3
According to the apparatus, the tomographic image for display of the imaged position is generated and displayed in real time in synchronization with the imaging speed at which the subject is imaged, and the production tomographic image is reproduced with respect to the displayed tomographic image for display in real time. Since the composition range is specified, the production image reconstruction range can be specified quickly.

The X-ray CT apparatus according to claim 4 is
The X-ray CT apparatus according to claim 1, wherein a plurality of types of display tomographic images viewed from different directions are generated based on the plurality of display tomographic images of the imaging range generated by the simplification reconstruction unit. The image display means displays the plurality of types of display tomographic images in parallel, and the range designating means displays the plurality of types of display images displayed on the image display means according to an input instruction. It is characterized in that a production image reconstruction range is designated for the tomographic image.

(Operation / effect) X-ray CT according to claim 4
According to the apparatus, a plurality of types of display tomographic images viewed from different directions are displayed in parallel, and a production image reconstruction range can be specified for the plurality of types of display tomographic images. Can be specified more easily, and the required production image reconstruction range can be specified very accurately.

The X-ray CT apparatus according to claim 5 is
The X-ray CT apparatus according to claim 4, wherein the image processing means selects one of the axial plane image, the coronal plane image, the sagittal plane image, and the oblique plane image as a plurality of types of display tomographic images viewed from different directions. It is characterized by generating two or more.

(Operation / effect) X-ray CT according to claim 5
According to the apparatus, two or more axial plane images, coronal plane images, sagittal plane images, or oblique plane images are generated and displayed as a plurality of types of display tomographic images viewed from different directions. Since the production image reconstruction range is specified for each type of surface image, it is easier to specify the production image reconstruction range, and the required production image reconstruction range should be specified very accurately. You can

The present specification also discloses an invention relating to a method of designating a reconstruction range in the following X-ray CT apparatus.

(1) A display process of displaying a rough display tomographic image and a range designating process of designating a range for reconstructing a fine production tomographic image on the display tomographic image are provided. A method of designating a reconstruction range in an X-ray CT apparatus.

(Operation / Effect) According to the above invention, a rough display tomographic image is displayed, and a range for reconstructing a fine production tomographic image is specified on the display tomographic image. It is possible to reconstruct the production image only for the specified range of the imaging range of, and to generate only the production tomographic image of the specified range, and to store the acquired production tomographic image, film printing, etc. It does not increase the burden.

(2) In the method for designating a reconstruction range in the X-ray CT apparatus according to (1), in the display process, a plurality of display tomographic images in the imaging range are displayed in parallel in the imaging order, and the range is displayed. The method of designating a reconstruction range in an X-ray CT apparatus is characterized in that the range is designated for a plurality of display tomographic images displayed in parallel in the designating step.

(Operation / Effect) According to the above invention, the X-ray C
Since the production image reconstruction range is specified for a plurality of display tomographic images in the imaging range displayed in parallel in the order of T imaging, the production image reconstruction range can be easily specified, which is required. It is possible to accurately specify the production image reconstruction range.

(3) In the method of designating the reconstruction range in the X-ray CT apparatus according to (1), a plurality of types of display images viewed from different directions are displayed based on a plurality of display tomographic images in the imaging range. An image generation process for generating a tomographic image is provided, the display process displays the generated multiple types of display tomographic images in parallel, and the range specifying process is performed on the displayed multiple types of display tomographic images. A method for designating a reconstruction range in an X-ray CT apparatus, characterized in that the range is designated.

(Operation / Effect) According to the above invention, a plurality of types of display tomographic images viewed from different directions are displayed in parallel,
Since the production image reconstruction range can be specified for the plurality of types of display tomographic images, the production image reconstruction range can be more easily specified, and the required production image reconstruction range can be greatly reduced. Can be specified exactly.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to the drawings. <First Embodiment> FIG. 1 is a block diagram showing the overall configuration of a multi-slice type X-ray CT apparatus according to the first embodiment, and FIG. 2 is a schematic view of an imaging system of the X-ray CT apparatus of the first embodiment. FIG. 3 is a schematic diagram showing a configuration, and FIG. 3 is a plan view showing an arrangement state of X-ray detection elements in the X-ray detector.

The X-ray CT apparatus according to the first embodiment is an X-ray tube 1 as an X-ray source for irradiating the subject M with an X-ray fan beam FB (hereinafter, appropriately abbreviated as X-ray beam FB).
And a large number of X-ray detection elements 2a are arranged in a line in the spreading direction (horizontal spreading) of the X-ray beam FB, and the X-ray detection data is detected for each X-ray with irradiation of the X-ray beam FB. The X-ray imaging mechanism 3 in which a multi-channel X-ray detector 2 that outputs each element 2a is arranged to face each other across the subject M, and the X-ray tube 1 and the X-ray detector 2 are arranged to face each other. An imaging mechanism rotation drive unit 4 arranged on the gantry G for rotating the subject M around the body axis Z while maintaining the same;
A top plate 5 that reciprocates in the direction of the body axis Z of the subject M (direction perpendicular to the paper surface) and moves in and out of the gantry G while the subject M is placed is provided.

When performing X-ray CT imaging, this X-ray CT apparatus moves the top plate 5 on which the subject M is placed in the direction of the body axis Z of the subject M (direction perpendicular to the paper surface). Then, while rotating the X-ray tube 1 and the X-ray detector 2 around the body axis Z of the subject M, X-ray detection is performed as the subject M is irradiated with the X-ray beam FB from the X-ray tube 1. Based on the X-ray detection data (X-ray detection signal) output from the device 2, an appropriate production image reconstruction process is performed, and finally the production tomographic image (X-ray C
T image) is created. Below, the first
The configuration of each part of the X-ray CT apparatus of the embodiment will be specifically described.

As shown in FIG. 1, the X-ray imaging mechanism 3 has a collimator 1a for shaping the X-ray beam emitted from the X-ray tube 1 at a position in front of the X-ray tube 1 inside the gantry G.
Is equipped with. The X-ray beam emitted from the X-ray tube 1 is arranged in a fan shape by the collimator 1a.

Further, since this X-ray CT apparatus is of the multi-slice type, the X-ray detector 2 uses the X-ray beam F
The X-ray detection element array line 2A (element array) composed of the X-ray detection elements 2a arranged in a line along the spread direction of B is not a single row but a plurality of rows as shown in FIG. 2 and FIG. (In this first embodiment, for example, four rows) of X-ray detection element array lines 2A are arranged so as to be adjacent to each other in the direction of the body axis Z of the subject M, and are arranged in four slice planes at a time. Since the X-ray detection data is obtained, the X-ray CT apparatus according to the first embodiment is suitable for imaging a wide imaging range. The number of channels (the number of X-ray detection elements 2a) in each X-ray detection element array line 2A is usually about 10.
It is around 00, and in the case of the first embodiment, for example, 100
Channel 0 is assumed.

As shown in FIG. 1, the image pickup mechanism rotation drive unit 4 transmits the rotational force of the motor 6 to the rotary ring 9 via the pulley 7 and the belt 8 and, as a result, the rotary ring 9 is rotated.
Is configured to rotate. The X-ray tube 1 and the X-ray detector 2 of the X-ray imaging mechanism 3 are fixed to the rotating ring 9, and as the rotating ring 9 rotates in conjunction with the forward or reverse rotation of the motor 6, the X-ray tube 1 And the X-ray detector 2 rotates around the body axis Z of the subject M. The image pickup mechanism rotation drive unit 4 is configured to execute a necessary rotation drive operation under the control of the image pickup mechanism control unit 10.

Further, the irradiation control section 11 controls the tube voltage / tube current to the X-ray tube 1 of the high voltage generating section 11a according to the set irradiation conditions from the main control section 16. The X-ray detection data output from the X-ray detector 2 in association with the irradiation of the X-ray beam FB from the X-ray tube 1 is collected by the data collecting unit (DAS) 13 and digitally converted, and then output to the subsequent stage. To be done.

Further, the top 5 is reciprocated in the direction of the body axis Z of the subject M under the control of the top drive unit 12. Therefore, the position moving means for moving the X-ray tube 1 and the X-ray detector 2 relative to the subject M along the direction of the body axis Z of the subject M by the top 5 and the top driving unit 12. Will be configured. The control of the imaging mechanism control unit 10, the irradiation control unit 11, or the top plate drive unit 12 is timely performed by the main control unit 16 according to an input operation from the input device 14 such as a console or a mouse or the imaging progress situation. It is configured to be executed according to a command signal or the like sent to the. The imaging mechanism rotation drive unit 4 and the top plate drive unit 12 correspond to the scanning means of the present invention.

On the other hand, in the X-ray CT apparatus of the first embodiment, in the subsequent stage of the data acquisition unit 13, the X-ray detection data of the digital signal output from the X-ray detector 2 is applied between the X-ray detection elements 2a. A data pre-processing unit 15a for correcting an error due to variations in sensitivity of the data, a reconstruction processing unit 15 for performing an image reconstruction process based on the X-ray detection data pre-processed by the data pre-processing unit 15a, and finally A CT image memory 17 for storing a production tomographic image (X-ray CT image) is provided. In addition to this, the X-ray CT apparatus prints an X-ray CT image on a film or the like, and a display monitor 18 for displaying the X-ray CT image in accordance with an input operation from the input device 14 or the like or a command from the main control unit 16. Image printing device 19 for outputting
And so on.

The reconstruction processor 15 is a data preprocessor 15
a detection data memory 20 for storing the preprocessed X-ray detection data output from a for a period necessary for processing, and preprocessed X-ray detection data output from the detection data memory 20, that is, scanning The X-ray detection data of the X-ray detector 2 obtained at each position is subjected to a simplification image reconstruction process which is a process simplified as compared with the production image reconstruction process,
And a simplification image reconstructing unit 21 that generates a display tomographic image that is simplified compared to the production tomographic image in the imaging range in which the image is captured.

The "simple image reconstructing process" referred to in this embodiment is an image reconstructing process which is simplified as compared with the production image reconstructing process, that is, a rough display as compared with a dense production tomographic image. This is what will be described next among the image reconstruction processing for generating a tomographic image for use. That is, in order to inform a doctor or a surgeon of the progress of X-ray CT imaging, a simple tomographic image (display tomographic image) of a portion of the imaging range where imaging has been completed is linked with X-ray CT imaging. (Image) is a rough image reconstruction process for sequentially displaying images in real time on the display monitor 18.
For example, the size of the production tomographic image is a matrix of 512 × 512, whereas the size of the display tomographic image is a matrix of 256 × 256. By reconstructing an image by partially deleting a reconstruction step such as partially deleting a part corresponding to a path, a tomographic image for display can be generated in a very short time. From this, the display tomographic image is a rough tomographic image as compared with the dense production tomographic image.

The simplified image reconstructing section 21 sequentially generates a display tomographic image with a predetermined slice thickness at predetermined time intervals and outputs it to the display monitor 18. The simplification image reconstruction unit 21 corresponds to the simplification reconstruction means of the present invention.

The display monitor 18 displays the display tomographic images sequentially output from the simplification image reconstruction unit 21 in real time so as to interlock with X-ray CT imaging. Figure 4
As shown in (a), the display monitor 18 displays the display tomographic images KG sequentially output from the simplification image reconstruction unit 21 on its screen in real time, and along with the progress of X-ray CT imaging. The number of display tomographic images KG displayed in real time increases, and as a result, a plurality of display tomographic images KG are displayed in parallel. In FIG. 4A, X
The display tomographic images KG are displayed in the order shown by the arrows along the progress of the line CT imaging, for example, 4 horizontal × 4 vertical = 1
Six display tomographic images KG are displayed. The display monitor 18 described above corresponds to the image display means of the present invention.

Further, the X-ray CT apparatus of the first embodiment specifies the production image reconstruction range for the display tomographic image KG displayed on the display monitor 18 according to the input instruction. The designating unit 22 is provided. The operator confirms the plurality of display tomographic images KG displayed in real time on the display monitor 18 shown in FIG. 4A and operates the input device 14 to operate the display tomographic image on the display monitor 18. When a production image reconstruction range is input to the image KG, the production reconstruction range designating unit 22 detects the production image reconstruction range according to the input instruction.
Instruct.

Specifically, as shown in FIG. 4A, the display tomographic image, which is the start position of the production image reconstruction range, is selected from the plurality of display tomographic images KG on the display monitor 18. By selecting the image KG and the display tomographic image KG which is the end position of the production image reconstruction range, the production image reconstruction range is instructed to be input to the production reconstruction range designating unit 22. FIG. 4A shows that all of the display tomographic images KG surrounded by the thick frame are in the production image reconstruction range. In other words, from the third tomographic image for display KG (third display tomographic image KG) from the left of the uppermost stage (first stage) to the second tomographic image from the left of the lowermost stage (fourth stage from the top). Twelve images up to the image KG (14th display tomographic image KG) are designated as the production image reconstruction range. The detection data memory 20 corresponds to the production image reconstruction range,
Pre-processed X-ray detection data stored inside, that is, X-ray detector 2 obtained at each scanning position already acquired
X-ray detection data of
Output to. In addition, the above-mentioned production reconstruction range designation unit 2
2 corresponds to the range designating means of the present invention.

Further, in the X-ray CT apparatus of the first embodiment, of the preprocessed X-ray detection data stored in the detection data memory 20, the production image designated by the production reconstruction range designating section 22 is selected. Pre-processed X-ray detection data corresponding to the reconstruction range, that is, X-ray detection corresponding to the production image reconstruction range in the already acquired X-ray detection data of the X-ray detector 2 at each scanning position. The X-ray detection data of the device 2 is provided with a production image reconstructing unit 23 that reconstructs a production image to generate a production tomographic image in the production image reconstruction range.

The production tomographic image of the production image reconstruction range generated by the production image reconstruction unit 23 is stored in the CT image memory 17, and is appropriately displayed on the display monitor 18 by the operation of the input device 14. , Or stored in a film or the like by the image printer 19.

Next, a process of progressing X-ray CT imaging by the X-ray CT apparatus of the first embodiment having the above-mentioned structure will be described with reference to the drawings. FIG. 5 is a flow chart showing the progress of X-ray CT imaging by the apparatus of the first embodiment.

[Step S1] A fluoroscopic image for positioning is picked up. Specifically, the subject M placed on the top plate 5
X that irradiates the subject M with X-rays, which are arranged to face each other across the X-axis
An X-ray detector 2 for detecting X-rays transmitted through the X-ray tube 1 and the subject M is positioned at a desired position around the body axis Z of the subject M, and the subject M is moved around the body axis Z at a desired position. Fluoroscopic imaging is performed to obtain a fluoroscopic image for positioning that is fluoroscopically imaged from the direction.

[Step S2] Based on the fluoroscopic image for positioning obtained in the above-mentioned step S1, the setting of the imaging range for the X-ray CT imaging of the region of interest of the subject M, so-called X-ray C
Positioning of T imaging is performed.

[Step S3] When the imaging range is set in step S2, the X-ray C for the imaging range is set.
Execution of T imaging and real-time display of the tomographic image for display are performed. Specifically, when the operator inputs a command to start X-ray CT imaging from the input device 14, movement of the subject M in the body axis Z direction starts and irradiation of the X-ray beam FB from the X-ray tube 1 starts. Collection of the X-ray detection data output from the X-ray detector 2 starts. The X-ray detection data of the X-ray detector 2 is preprocessed by the data preprocessing unit 15a and stored in the detection data memory 20. The simplification image reconstruction unit 21
The pre-processed X-ray detection data stored in the detection data memory 20 is subjected to a simplified image reconstruction process to display a simplified image in the imaging range of the subject M as compared with the production tomographic image. The tomographic images are sequentially generated and output to the display monitor 18. The display monitor 18 is shown in FIG.
As shown in, the display tomographic images KG sequentially output from the simplification image reconstruction unit 21 are displayed in real time so as to be linked to the X-ray CT imaging. Note that this step S3
The real-time display of the display tomographic image KG in (1) corresponds to an aspect of the display process of the present invention.

[Step S4] The production image reconstruction range is designated for the display tomographic image displayed in real time. Specifically, when the operator operates the input device 14 to input the production image reconstruction range to the display tomographic image on the display monitor 18, the production reconstruction range designating unit 22. Instructs the detection data memory 20 of the production image reconstruction range in accordance with the input instruction. That is,
As shown in FIG. 4A, from among the plurality of display tomographic images KG on the display monitor 18, the display tomographic image KG which is the start position of the production image reconstruction range and the production image thereof. The display tomographic image KG which is the end position of the reconstruction range is selected by the operator, and all of the display tomographic images KG surrounded by the thick frame become the production image reconstruction range. Figure 4
As shown in (b), it can be seen that a desired range of the imaging range of the subject M subjected to X-ray CT imaging is designated as the production image reconstruction range. The designation of the production image reconstruction range in step S4 corresponds to one aspect of the range designation process of the present invention.

Then, the pre-processed X-ray detection data in the detection data memory 20 corresponding to the production image reconstruction range, that is, the X of the X-ray detector 2 obtained at each scanning position already acquired. The line detection data is used as the production image reconstruction unit 23.
Is output to. In this way, a desired range within the imaging range for X-ray CT imaging the subject M can be designated as the production image reconstruction range.

If the X-ray CT imaging is continuing when the production image reconstruction range is set, the X-ray CT imaging is completed relatively quickly after the production image reconstruction range is set. To do. In FIG. 4A, the display tomographic image KG at the lower right is displayed.
The X-ray CT imaging is completed when the (16th display tomographic image KG) is displayed in real time.

[Step S5] Production CT reconstruction is executed, that is, a production tomographic image is generated for the production image reconstruction range. Specifically, the production image reconstruction unit 23
Is a production image reconstruction processing of the production image reconstruction processing of the X-ray detection data of the X-ray detector 2 obtained at each scanning position which has already been acquired and corresponds to the production image reconstruction range. A production tomographic image is generated for. X-ray CT imaging
It is executed in the above-described steps S3 to S4, and in this step S5, only the production image reconstruction processing (calculation) of generating the production tomographic image in the production image reconstruction range is performed. The production tomographic image for the production image reconstruction range is stored in the CT image memory 17, and by the operation of the input device 14 by the operator,
It is appropriately displayed on the display monitor 18 or is appropriately stored on a film or the like by the image printing device 19.

As described in detail above, according to the X-ray CT apparatus of the first embodiment, a desired range of the imaging range for subjecting the subject M to X-ray CT imaging is designated as the production image reconstruction range. Therefore, the production image can be reconstructed only in the designated range of the imaging range of the subject M, and only the production tomographic image in the designated range can be generated. In other words, the image reconstruction outside the specified range, that is, the production image reconstruction for generating the unnecessary production tomographic image is not executed, and the unnecessary production tomographic image may increase. Since it does not exist, the burden of storing the acquired production tomographic image and film printing does not increase. It is also possible to specify the range for reconstructing the production image for the display tomographic image that has been actually captured and subjected to the simplification image reconstruction process, and only specify the production image reconstruction process for the specified range. Since it is possible to obtain a production tomographic image in a range and there is no need to perform re-exposure, it is possible to generate a minimum necessary production tomographic image without increasing the number of exposures.

In addition, the positioning using the fluoroscopic image for positioning as in the conventional example was not able to perform the strict positioning, but the X-ray CT apparatus according to the first embodiment actually picked up and generated the image. Since the position and range can be set based on the display tomographic image, the minimum number of production tomographic images can be strictly set.

Further, since the production image reconstruction range is specified for a plurality of display tomographic images in the imaging range displayed in parallel in the imaging order, the production image reconstruction range can be easily specified. It is possible to accurately specify the required production image reconstruction range.

Further, the display tomographic image at the imaged position is generated and displayed in real time in synchronization with the image pickup speed for picking up the subject M, and the production image is displayed with respect to the realtime displayed display tomographic image. Since the reconstruction range is specified, the production image reconstruction range can be specified quickly.

<Second Embodiment> FIG. 6 is a block diagram showing the overall arrangement of a multi-slice type X-ray CT apparatus according to the second embodiment.

The X-ray CT apparatus according to the second embodiment is the same as the first embodiment described above.
This is different from the first embodiment described above in that an image processing unit 24 described later is added to the reconstruction processing unit 15 of the X-ray CT apparatus of the embodiment. Since the configuration other than the reconfiguration processing unit 15 is the same as that of the first embodiment described above, the same parts are denoted by the same reference numerals, and in the second embodiment, this second embodiment is used.
The image processing unit 24 of the reconstruction processing unit 15, which is a characteristic part of the embodiment, will be described in detail.

The image processing unit 24 is provided after the simplification image reconstruction unit 21 in the reconstruction processing unit 15, and is used for displaying a plurality of imaging ranges generated by the simplification image reconstruction unit 21. A plurality of types of display tomographic images viewed from different directions are generated based on the tomographic image. In the second embodiment, an axial plane image (body axis image) orthogonal to the body axis Z of the subject M is obtained.
And a coronal plane image (coronal image) on a plane parallel to the front surface of the subject M and orthogonal to the axial image, and a sagittal plane image (sagittal image) on a plane orthogonal to the front surface of the subject M and the axial image. And three types of display tomographic images are generated. The image processing unit 24 performs the above-mentioned 3 by performing image processing such as simple projection, MIP (maximum intensity projection), and volume rendering.
Types of display tomographic images are generated.

The above-described three types of display tomographic images generated by the image processing unit 24 are output to the display monitor 18 and are displayed in parallel on the screen of the display monitor 18. Figure 7
As shown in (a), the screen of the display monitor 18 is divided into four display areas of upper left, upper right, lower left, and lower right, and an axial image is displayed in the lower left area of the screen. The coronal plane image is displayed in the upper left area of the screen, and the sagittal plane image is displayed in the lower right area of the screen. On the axial surface image, the coronal surface image, and the sagittal surface image, a rectangular box cursor BC indicating the image reconstruction range for production is displayed, and one of the axial surface image, the coronal surface image, and the sagittal surface image is displayed. When the size or position of the box cursor BC is changed, the box cursor B of the other plane image is changed.
The size and position of C are changed together. As shown in FIG. 7B, it can be seen that a desired range in the X-ray CT imaging range of the subject M is designated as the production image reconstruction range.

Next, a process of progressing X-ray CT imaging by the X-ray CT apparatus of the second embodiment having the above-mentioned structure will be described with reference to FIG. FIG. 8 is a flowchart showing the progress of X-ray CT imaging by the apparatus of the second embodiment.

Since only step S4 'of the second embodiment shown in FIG. 8 is different from step S4 of the first embodiment shown in FIG. 5, this second embodiment is shown in FIG. The step S4 'will be described in detail.

[Step S4 ′] The image processing unit 24, based on the plurality of display tomographic images generated by the simplification image reconstruction unit 21, that is, the plurality of display tomographic images displayed in real time, An axial plane image, a coronal plane image, and a sagittal plane image (three types of display tomographic images) are generated by image processing such as cross-section conversion. Incidentally, the X-ray CT imaging is completed at the time of entering this step S4 '.
The display monitor 18 displays the axial plane image, the coronal plane image, and the sagittal plane image generated by the image processing unit 24 in parallel. When the operator operates the input device 14,
As shown in (a), when the size or position of the box cursor BC on the axial surface image, the coronal surface image, and the sagittal surface image displayed in parallel on the display monitor 18 is changed (input instruction), the reproduction for production is performed. According to the input instruction, the configuration range designation unit 22 instructs the detection data memory 20 to set the production image reconstruction range. Then, the pre-processed X-ray detection data in the detection data memory 20 corresponding to the production image reconstruction range, that is, the X-ray detection data of the X-ray detector 2 obtained at each scanning position already acquired Is output to the production image reconstructing unit 23. In this way, the subject M is subjected to X-ray CT.
A desired range of the imaging range to be imaged can be designated as the production image reconstruction range (see FIG. 7B).
Note that the generation of the three types of display tomographic images in step S4 ′ corresponds to one aspect of the generation process of the present invention, and the designation of the production image reconstruction range in step S4 ′ is performed by the present invention. This corresponds to one mode of the range designation process.

Then, in step S5, a production tomographic image is generated for the production image reconstruction range.

As described in detail above, according to the X-ray CT apparatus of the second embodiment, in addition to the effects of the first embodiment, the axial surface image, the coronal surface image and the sagittal surface image are displayed in parallel. However, since the production image reconstruction range can be specified for each of these surface images, it becomes easier to specify the production image reconstruction range, and the required production image reconstruction range is very accurate. Can be specified. In addition, the center of the image, the size of the reconstructed field of view, etc.
Since it can be set based on the tomographic image for display (axial surface image, coronal surface image, and sagittal surface image) generated by simplifying the T image (production tomographic image), there is no need to capture an additional positioning perspective image. it can.

Further, in the printing work on the film performed after the X-ray CT imaging, conventionally, the production tomographic image was manually selected and the image quality adjustment such as the range, the window level, the enlargement ratio and the visual field size was performed. When printing later or performing automatic film printing, when selecting the tomographic image for production and adjusting the image quality, for example, when you want to change the size of the field of view, when the region of interest is far from the center, or when the contrast is poor , I had to divide. However, according to the X-ray CT apparatus of the second embodiment, when setting the production image reconstruction range using the tomographic image for display, image quality adjustment such as range, window level, enlargement ratio, and field size is performed at the same time. Therefore, it is possible to automate the film printing operation of the production tomographic image without compromising.

The present invention is not limited to the above embodiment, but can be modified as follows.

(1) In the X-ray CT apparatus of the first embodiment described above, a plurality of tomographic images for display are simultaneously displayed in parallel on the display monitor 18, but one for display is displayed on the display monitor 18. Only the tomographic image is displayed, and the display tomographic image that is the start position of the production image reconstruction range and the end position of the production image reconstruction range are displayed for the display tomographic images that are individually displayed in time series. The display image tomographic image to be displayed may be selected to set the production image reconstruction range.

(2) In the above-described first embodiment, the display tomographic image KG is set as the start position of the production image reconstruction range.
And the display tomographic image KG which is the end position of the production image reconstruction range is set to set the production image reconstruction range. However, as shown in FIG. The production image reconstruction range may be set finely. In this case, when setting the production image reconstruction range using the display tomographic image, the range, window level, enlargement ratio, field size, etc. can be adjusted at the same time. Work automation can be done without compromise.

(3) In the X-ray CT apparatus according to the second embodiment described above, three types of axial tomographic images, coronal tomographic images and sagittal tomographic images are displayed as a plurality of types of display tomographic images viewed from different directions. Although they are displayed in parallel on the monitor 18, two or more of an axial surface image, a coronal surface image, a sagittal surface image, or an oblique surface image may be displayed in parallel on the display monitor 18. Oblique plane image (oblique image)
Is a tomographic image in any direction other than the axial plane image, the coronal plane image, and the sagittal plane image.

(4) In each of the above-described embodiments, the top plate 5 on which the subject M is placed is moved to the top plate driving unit so that the gantry G including the X-ray tube 1 and the X-ray detector 2 moves in and out. Although it is moved by 12, the top plate 5 may be fixed and the gantry G may be moved, or both the top plate 5 and the gantry G may be moved.

(5) In each of the above embodiments, step S
In 1 to S2, the fluoroscopic image for positioning is imaged and the imaging range is set for it, but the imaging range may be set using a light projector or the like.

(6) The X-ray CT apparatus of the above-mentioned embodiment is
By rotating the X-ray tube 1 and the X-ray detector 2 once around the body axis Z of the subject M while sandwiching the subject M, X-rays in the entire circumferential direction at a specific measurement position of the subject M. The detection data is acquired, and the top plate 5 on which the subject M is placed is step-fed at a predetermined feed pitch in the direction of the body axis Z of the subject M to obtain the subject M.
The scanning method is one in which the X-ray detection data in the omnidirectional direction at the next measurement position is acquired, and the scanning method is one step after one rotation, but the scanning method is not limited to this scanning method. The present invention can also be applied to the case of a scan system that simultaneously performs rotation and feed, such as a system that performs helical scan.

(7) The X-ray CT apparatus of the embodiment was a multi-slice type apparatus in which four rows of X-ray detecting element array lines 2A were provided, but the X-ray CT apparatus of the present invention is an X-ray CT apparatus. It may be a multi-slice type device having a plurality of detection element array lines 2A other than four, or may be a single slice type (non-multi-slice type) device having only one X-ray detection element array line 2A. . Further, the X-ray tube 1 is of a type that emits a cone-beam X-ray, and a flat panel X-ray detector (FPD) is used instead of the X-ray detector 2 so that the X-ray imaging mechanism 3 is a cone. A beam scan type may be used.

[0075]

As described above in detail, the X-ray C of the present invention
According to the T apparatus, a desired range of the imaging range for X-ray CT imaging of the subject can be designated as the production image reconstruction range. Therefore, only the designated range of the imaging range of the subject can be used for the production image. It can be reconstructed, and only the production tomographic image in the specified range can be generated.
It is also possible to specify the range for reconstructing the production image for the display tomographic image that has been actually captured and subjected to the simplification image reconstruction process, and only specify the production image reconstruction process for the specified range. Since it is possible to obtain a production tomographic image in a range and there is no need to perform re-exposure, it is possible to generate a minimum necessary production tomographic image without increasing the number of exposures.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of an X-ray CT apparatus according to a first embodiment.

FIG. 2 is a schematic diagram showing a schematic configuration of an imaging system in the X-ray CT apparatus according to the first embodiment.

FIG. 3 is a plan view showing an arrangement state of X-ray detection elements in the X-ray detector of the first embodiment device.

FIG. 4A is a diagram for explaining multi-frame display of a display monitor screen of the apparatus of the first embodiment and designation of a production image reconstruction range, and FIG. 4B is an image reconstruction for an imaging range. It is the figure which showed the range typically.

FIG. 5 is a flowchart showing the progress of X-ray CT imaging by the X-ray CT apparatus according to the first embodiment.

FIG. 6 is a block diagram showing an overall configuration of an X-ray CT apparatus according to a second embodiment.

FIG. 7A is a diagram for explaining three-section display on the display monitor screen of the apparatus of the second embodiment and designation of a production image reconstruction range, and FIG. 7B is an image reconstruction for an imaging range. It is the figure which showed the range typically.

FIG. 8 is a flowchart showing the progress of X-ray CT imaging by the X-ray CT apparatus according to the second embodiment.

FIG. 9A is a diagram for explaining designation of a production image reconstruction range of an embodiment different from the first embodiment, and FIG.
FIG. 4 is a diagram schematically showing an image reconstruction range with respect to an imaging range.

[Explanation of symbols]

1 ... X-ray tube (X-ray source) 2 ... X-ray detector 4 ... Imaging mechanism rotation drive section (scanning means) 12 ... Top drive unit (scanning means) 18 ... Display monitor (image display means) 21 ... Simplified image reconstruction unit (simplified reconstruction means) 22 ... Production reconstruction range designation section (range designation means) 23 ... Production image reconstruction unit (production reconstruction means) 24 ... Image processing unit (image processing means) KG ... Display tomographic image M ... Subject Z ... Body axis

Claims (5)

[Claims] 1. An (a) X-ray source that irradiates a subject with X-rays, and (b) is arranged to face the X-ray source with the subject interposed therebetween.
An X-ray detector for detecting X-rays transmitted through the subject, and (c)
Scanning means for scanning the X-ray source and the X-ray detector around the body axis of the subject; and (d) the X obtained at each scanning position.
The X-ray detection signal of the line detector is subjected to the simplified image reconstruction processing,
A simplified reconstructing means for generating a simplified display tomographic image in comparison with the production tomographic image within the imaging range in which the subject is imaged; and (e) the display reconstructing means generated by the simplified reconstructing means. Image display means for displaying a tomographic image; (f) range specifying means for specifying a production image reconstruction range for the display tomographic image displayed on the image display means according to an input instruction; The X-ray detection signal of the X-ray detector at each acquired scanning position corresponding to the production image reconstruction range designated by the range designating means is subjected to production image reconstruction processing to produce the production image reconstruction. An X-ray CT apparatus comprising: a production reconstructing unit that produces a production tomographic image for a configuration range. 2. The X-ray CT apparatus according to claim 1, wherein the image display unit displays a plurality of display tomographic images in the imaging range in parallel in the imaging order, and the range designating unit follows an input instruction. An X-ray CT apparatus characterized in that a production image reconstruction range is designated for a plurality of display tomographic images displayed on the image display means. 3. The X-ray C according to claim 1 or 2.
In the T-apparatus, the simplification reconstructing unit generates a tomographic image for display at the imaged position in association with the imaging speed for imaging the subject, and the image display unit is the simplification reconstructing unit. An X-ray CT apparatus characterized in that the display tomographic image generated by the means is displayed in real time so as to be linked to the imaging speed. 4. The X-ray CT apparatus according to claim 1, wherein a plurality of types of display are viewed from different directions based on a plurality of display tomographic images of the imaging range generated by the simplification reconstructing means. Image display means for generating a tomographic image for display, the image display means displays the plurality of types of display tomographic images in parallel, and the range designating means displays the image displayed on the image display means according to an input instruction. An X-ray CT apparatus characterized by designating a production image reconstruction range for a plurality of types of display tomographic images. 5. The X-ray CT apparatus according to claim 4, wherein the image processing unit uses a plurality of types of display tomographic images viewed from different directions as an axial plane image, a coronal plane image, a sagittal plane image, or an oblique plane image. An X-ray CT apparatus characterized in that two or more of the surface images are generated.