JP2001204725A - X-ray ct device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray CT device capable of speedily obtaining an image having three-dimensional information useful for improving diagnosis supporting ability. SOLUTION: In addition to obtaining a two-dimensional CT image concerning an observing object site (target position), plural two-dimensional CT images are obtained in its neighborhood and weighting adding processing is performed to these respective CT images to obtain the image added with the three dimensional information.

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, and more particularly to an X-ray CT apparatus capable of adding three-dimensional information to a two-dimensional CT image to enhance its diagnostic support capability.
Related to the device.

[0002]

2. Description of the Related Art An X-ray CT apparatus irradiates an X-ray while scanning the periphery of a subject with a predetermined slice thickness in a direction intersecting the body axis of the subject (patient), thereby irradiating the subject with a tomographic image (tomographic image). CT image). Therefore, the image obtained by the X-ray CT apparatus is basically a two-dimensional image on a plane intersecting the body axis of the subject, and information on the body axis direction (Z direction) of the subject, that is, three-dimensional information Is not included. Therefore, a device has been devised to enhance the diagnostic support capability of the X-ray CT apparatus. As one of such ideas, a plurality of CT images are acquired in the body axis direction (Z direction) of the subject, and a three-dimensional image is obtained by performing shading based on information from each of the CT images. There are volume rendering methods and surface rendering methods that can be obtained (method 1). Another method is a Maximum Intensity Projection (MIP) method in which a plurality of CT images are similarly acquired in the Z direction, and the maximum value of the pixel values of each CT image is projected on one image (method 2).

[0003]

The above-mentioned method 1 has a great effect of improving the diagnostic support ability because a three-dimensional image is obtained. However, on the other hand, there is a problem that the image processing time becomes long because many calculation processes are required. On the other hand, the method 2 can perform processing only by comparing each pixel value in the Z direction, so that the image processing time is shorter than the method 1, but information in the depth direction (three-dimensional information) is missing. Therefore, the effect of enhancing the diagnosis support ability is lower than that of the method 1.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides an X-ray CT system capable of obtaining in a short time an image having information in the depth direction which is useful for enhancing the diagnostic support capability. It is intended to provide equipment.

[0005]

According to the present invention, there is provided an X-ray image processing apparatus comprising an image processing apparatus capable of adding three-dimensional information to a two-dimensional CT image of a region to be observed in a subject. In the line CT apparatus, in addition to acquiring a two-dimensional CT image of the observation target site, a plurality of two-dimensional CT images are acquired in the vicinity thereof, and each of these CT images is acquired.
It is characterized in that the three-dimensional information is added by performing weighted addition processing on the image.

In the present invention, a function that changes the weight according to the distance of each CT image from the observation target site is used as a weighting function for weighting.

According to the present invention, when an image obtained by the weighted addition processing is displayed in a cine format, a function for changing a weight in a moving direction in the cine display is used as a weight function for weighting. I have.

[0008]

Embodiments of the present invention will be described below. FIG. 2 shows a configuration of an image processing apparatus in an X-ray CT apparatus according to one embodiment of the present invention. As shown in the figure, the image processing apparatus includes a console 1, an image processing unit 2, a storage device 3, and a display 4. Then, the operator console 1 selects a two-dimensional CT image (tomographic image) as an observation target site, specifies a weighting function, and the like.
Then, a necessary CT image is read from the storage device 3 and subjected to a weighting process and an addition process. The storage device 3 stores the CT image before the three-dimensional information addition process and the added image after the three-dimensional information addition process. The display 4 is used for
Used to display necessary images.

FIG. 3 shows the flow of the weighted addition processing, that is, the three-dimensional information addition processing performed by such an image processing apparatus. First, the operator 1 specifies a weighting function g (z) using the position z in the body axis direction as a variable and a processing range (1, 2). Here, the weighting function g (z) is, as shown in FIG. 1, a part to be observed (a target position) and each CT image fi (x, y) (where i = 1 , 2...) Relative to the slice position z. More specifically, the weighting as decreases according to the distance z of the weighted addition target CT image with respect to the target position, i.e. the weight constant as _{z 0 g (z) = 1-} | a / z ₀ | z That is to do. The processing range refers to a range of CT images to be subjected to weighting addition processing with respect to a target position among a plurality of CT images acquired in advance and stored in the storage device 3.

As an initial process, the console 1 stores an area h (x, x) for storing an added image obtained by the weighted addition process.
y) is designated in the storage device 3, and all pixels in the area h (x, y) are initialized to 0 (3). Next, the leading image f ₁ (x, y, z) in the processing range specified above is read from the storage device 3 into the image processing unit 2 (5). Then, in the image processing unit 2,
All the pixels of this image f ₁ (x, y, z) are multiplied by a weighting function g (z) (6), and the result is added to the area h (x, y) (7). Then, returning to 4, it is determined whether or not the weighted addition processing has been completed for all the images in the processing range specified above. If not, the next image f
₂ (x, y, z) and the next image f ₃ (x, y, z), etc., are subjected to the above-described processes (5) to (7). As a result, the entire processing range is obtained in (4). If it is determined that the weighted addition processing has been completed for the image of the area h (x, y), the weighted addition image H (x, y) in the region h (x, y) is stored as an output image in the storage device 3 and the display is performed. 4 is displayed (8). The time required to create the added image H (x, y) by the above series of processing is, for example, about 7 seconds / 1 sheet. This is 1/12 or less as compared with the creation time of 90 seconds / 1 sheet required for the above-described volume rendering method.

The above processing example is an example in which only one specific part of the subject is set as an observation target part, and one weighted addition processing image is created therefrom. Alternatively, a plurality of observation target sites may be set on the subject, and a weighted addition processing image may be obtained for each of these sites. In that case, prior to the above (1), the creation range of the weighted addition processing image is also specified, and the processes (1) to (8) are performed on the entire creation range specified by this. Become.

The weighted and added image obtained by the above processing is also useful for cine display. Since the three-dimensional information is added to the cine display by the weighted addition processing image, it becomes easier to identify the blood vessel running and the like as compared with the cine display by the CT image before the processing. In addition, as described above, since processing can be performed in a much shorter time than a volume rendering method that provides a three-dimensional image, it is effective as a diagnostic support in lung cancer screening or the like that requires processing a large number of samples in a short time. is there. However, the weight function g (z) in the weighting addition process for cine display is shown in FIG.
As shown in FIG. 4, instead of using a function that decreases with respect to the distance z around the target position as shown in FIG. This is preferable because the dimensional position information can be more correctly recognized.

[0013]

As described above, according to the present invention, 3
It is possible to obtain an X-ray CT image to which dimensional information is added in a short time, thereby improving the diagnostic support capability of the X-ray CT apparatus and contributing to, for example, improving the efficiency of diagnosis in lung cancer screening and the like. it can.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a weighted addition process.

FIG. 2 is a flowchart of a process for creating one weighted addition image;

FIG. 3 is a configuration diagram of an image processing apparatus in the X-ray CT apparatus according to the present invention.

FIG. 4 is a conceptual diagram of a weighted addition process in the case of cine display.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Operation console 2 Image processing part 3 Storage device 4 Display

Claims (1)

[Claims] 1. A two-dimensional C of an observation target site in a subject
X equipped with an image processing device for adding three-dimensional information to a T image
In the line CT apparatus, in addition to acquiring a two-dimensional CT image for the observation target site, a plurality of two-dimensional CT images are acquired in the vicinity thereof, and a weighted addition process is performed on each of these CT images, whereby An X-ray CT apparatus to which three-dimensional information is added.