JP2003010173A - X-ray computed tomography apparatus and image processing apparatus - Google Patents

Abstract

(57) Abstract: An object of the present invention is to eliminate the need for scano imaging and designation of an azimuth marker in an X-ray computed tomography apparatus and image processing apparatus. The present invention provides a reconstruction apparatus for generating volume data based on projection data obtained by scanning a three-dimensional region of a subject with X-rays, and generating tomographic image data of an arbitrary cross section from the volume data. Tomographic image data generator 111, 3D model generator 113 for generating surface model data including a marker indicating a position of a cross section from volume data, and azimuth markers respectively corresponding to tomographic image data and surface model data. An azimuth marker generating device 117 and a synthesizing device 118 for synthesizing surface model data with tomographic image data together with the azimuth marker as an inset view are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generates volume data based on projection data acquired by scanning a three-dimensional region of a subject with X-rays, and generates tomographic image data of an arbitrary cross section from this volume data. The present invention relates to an X-ray computed tomography apparatus and an image processing apparatus.

[0002]

2. Description of the Related Art A helical scan, which is realized by a continuous movement of an X-ray tube and an X-ray detector and a continuous slide of a table top of a bed on which a subject is placed, is very fast. Achieves data collection of a three-dimensional region of a subject. In addition to this high-speed data acquisition, the speed of three-dimensional processing is increased by increasing the capacity of the memory and using a very large scale integrated circuit (VLSI), so that the X-ray computed tomography apparatus is rapidly becoming three-dimensional. There is.

By this helical scan, projection data in which the angle and the body axis position are continuously changed is acquired, and the projection data is passed through a volume reconstruction process to generate volume data concerning the three-dimensional region of the subject. .
Various 3D image data is generated using this volume data. As the types of three-dimensional images, maximum intensity projection (MIP) suitable for blood vessel display, surface display (surface model) that casts shadows according to the distance and angle from a light source in order to represent the morphology of organs or parts, In addition to shadowing, there are volume rendering that displays color with other information such as CT values, and fly-through images that allow free observation while moving the inner wall of the lumen. Although not a three-dimensional image in a strict sense, from the viewpoint of signal processing that handles volume data, cross-sectional transformation (MPR) that reconstructs a tomographic image by cutting out and interpolating data of an arbitrary cross-section from the volume data.
Is also included in the category. This MPR is indispensable for detailed image interpretation.

FIG. 5 shows a flow of a series of conventional processes in the X-ray computed tomography apparatus. First,
Scano photography is performed. As is well known, scanography is a work of scanning a wide range while fixing the X-ray tube at a certain rotation angle and moving the top plate, and thereby a plane transmission image such as an X-ray image is acquired. A scan range of volume scan (hereinafter referred to as 3D scan) is set using this scanogram (also referred to as a scanogram), 3D scan is performed within this range, and volume data within that range is generated with reconstruction processing. To be done.

Next, the operator sets the cross-sectional position on the scano with a line cursor or the like, and the data on the cross-section is cut out from the volume data and interpolated as necessary to generate tomographic image data (cross-section). Conversion process).
When the operator inputs a direction marker representing the left and right of the subject on this tomographic image, the direction marker is combined with the tomographic image and is displayed together with the scano including the line marker indicating the cross-sectional position. Then, the cross-sectional position is reset if necessary, and the same processing is repeated.

[0006] In such a series of flow, scanography has a problem in that the exposure dose is increased. However, in the conventional apparatus, the cross-sectional position cannot be presented when the scan range is specified or displayed unless the scanograph is performed. Further, since the operator designates the left and right direction markers, the designation work is not only complicated, but on the contrary, the possibility of erroneous designation is not zero.

[0007]

An object of the present invention is to provide an X-ray computed tomography apparatus and an image processing apparatus,
It is to eliminate the need for scanographing and designation of azimuth markers.

[0008]

According to the present invention, by generating tomographic image data of an arbitrary cross section generated from volume data and surface model data including a marker indicating a position of a cross section generated from the same volume data, It is possible to automatically generate azimuth markers respectively corresponding to the tomographic image data and the surface model data.

[0009]

DETAILED DESCRIPTION OF THE INVENTION An X-ray computed tomography apparatus according to the present invention will be described below with reference to embodiments. Note that X
In the X-ray computed tomography apparatus, a rotation / rotate type in which an X-ray tube and an X-ray detector system are rotated as one body around a subject, and a large number of detection elements arranged in a ring are fixed, There are various types such as a stationary / rotate type in which only the wire tube rotates around the subject, and the present invention can be applied to any type. Here, the rotate / rotate type, which is currently the mainstream, will be described. In addition to the currently mainstream 1-bulb system equipped with a pair of X-ray tube and detector system, multiple X-ray tubes and detector systems that have been developed for practical use in recent years, For example, the present invention is applicable to a multi-tube system equipped with 3 pairs,
For convenience, the one-tube system will be described below. further,
In order to reconstruct one tomographic image, projection data for about 360 degrees around the subject is required, and for the half scan method, projection data for 180 degrees + fan angle is required. The present invention can also be applied to this, but here, it is assumed that one tomographic image is reconstructed from a general projection data set for about 360 degrees of the former. Furthermore, the volume data can be acquired at a comparatively high speed by any of the multi-slice method and the helical scan method, and the present invention is applicable to any of them.
The helical scan method will be described below.

FIG. 1 is a block diagram showing the configuration of a computer tomography apparatus according to this embodiment. Figure 2
FIG. 9 shows a flowchart showing the flow of a series of processing from scanning to image display according to the present embodiment.

The scan gantry 107 includes a rotating ring 1.
02, and the X-ray tube 101 and the X-ray detector 103 are mounted on the rotating ring 102 so as to face each other. The X-ray tube 101 is configured to receive a high voltage pulse periodically generated from the high voltage generator 109 and radiate the X-ray in a fan shape. The X-ray detector 103 is composed of an ionization chamber type detector box or a semiconductor detector. X-ray detector 10
A data acquisition circuit 104 generally called a DAS (data acquisition system) is connected to 3.
The data acquisition circuit 104 includes an IV converter that converts a current signal of the X-ray detector 103 into a voltage, and an integrator that periodically integrates the voltage signal in synchronization with an X-ray exposure cycle. An amplifier that amplifies the output signal of the integrator and an analog-digital converter that converts the output signal of the preamplifier into a digital signal are provided for each channel.

The preprocessor 106 corrects the sensitivity nonuniformity between the channels with respect to the projection data detected by the data acquisition circuit 104, and also an extreme signal due to the X-ray strong absorber, mainly the metal part. Pre-processing such as correction of strength reduction or signal dropout is executed. Based on the projection data corrected by the preprocessing device 106, tomographic image data is generated by the reconstruction device 113 by the three-dimensional reconstruction method or the multi-slice reconstruction method, and is stored in the volume data storage device 112 as volume data. It The 3D scan range for acquiring volume data is set to a relatively wide range including the region of interest.

The input device 115 is provided for the operator to arbitrarily set the position of the cross section, and the tomographic data generator 111 on the cross section according to the position and angle of the cross section set via the input device 115. Data is cut out from the volume data, and interpolation processing is executed on the cut out data in order to make the resolutions uniform within the plane (section conversion processing). The tomographic data generated thereby is synthesized by the synthesizer 1.
Sent to 18. Also, the 3D model generator 113
Generate a three-dimensional image, typically a surface model, from the volume data. Furthermore, the 3D model generator 113
Overlays a surface marker representing the set position and angle of the cross section on this surface model data,
Send to.

As described above, the 3D model generator 113 and the tomographic data generator 111 respectively generate the surface model data and the tomographic data from the same volume data, in other words, the respective data from the volume data represented by the same coordinate system. Since the azimuth marker generator 117 generates the azimuth marker 117, it is possible to easily recognize the azimuths of the subject in the front, rear, left, and right directions in the same manner in the tomographic data and the surface model data. In order to recognize the front, rear, left, and right orientations of the subject, the relationship information between the front, rear, left, and right orientations of the subject and the coordinate system of the volume data is required, which is the characteristic part extracted from the surface model,
For example, it may be automatically determined from the positional information of both eyes or both ears, or the positional relationship of the nasal cavity, or the operator inputs the posture of the subject at the time of scanning for collecting volume data. It is possible to leave it. This azimuth marker is sent to the synthesizing device 118 and is synthesized into one frame (one screen) together with the tomographic data and the surface model data.

FIG. 3 shows an example of the display screen of the display device 116. As shown in this FIG.
Then, orientation markers (FRONT, REAR, LEFT, RIGHT) that represent the front, rear, left, and right of the subject are combined with the tomographic image, and similarly, the orientation markers (FRONT, REAR, LEF
T, RIGHT) is synthesized. Then, for the tomographic image, the surface model is displayed small in inset view, that is, for the tomographic image that occupies most of the screen, using a part of the screen to guide the cross-sectional position. It

As described above, since the surface model for representing the cross-sectional position of the tomographic image is displayed together with the orientation marker, the interpretation efficiency of the tomographic image is improved, and erroneous diagnosis due to misidentification of the orientation is avoided. Moreover, since this azimuth marker is automatically inserted, it does not lend the operator troublesome work and is accurate. Furthermore, since a surface model for expressing the cross-sectional position is generated from the volume data, scanographing is unnecessary.

In FIG. 4, in place of the surface model for representing the cross-sectional position, line markers representing the cross-sectional position are synthesized for each of two cross sections, coronal and sagittal, which intersect the cross section (axial) of the tomographic image. You may make it display it. Both of these coronal and sagittal are generated from the volume data used in the tomographic transformation.

Although the above description relates to the X-ray computed tomography apparatus, the present invention can be applied only to the portion that handles volume data, that is, the image processing apparatus portion. Furthermore, it is also applicable to other devices capable of three-dimensional image diagnosis such as a magnetic resonance imaging apparatus, a long image diagnostic apparatus, SPECT, and PET. Besides, the present invention is not limited to the above-described embodiment, and can be variously modified and implemented at the stage of implementation without departing from the scope of the invention.

[0019]

According to the present invention, in the X-ray computed tomography apparatus and the image processing apparatus, it is possible to eliminate the need for scanography and designation of the direction marker.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an X-ray computed tomography apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing the flow of a series of processing from scanning to image display according to the present embodiment.

FIG. 3 is a diagram showing a display example of an image according to the present embodiment.

FIG. 4 is a diagram showing another display example of an image according to the present embodiment.

FIG. 5 is a flowchart showing a flow of a series of processing from conventional scan imaging to image display.

[Explanation of symbols]

101 ... X-ray tube, 102 ... rotating ring, 103 ... X-ray detector, 104 ... a data collection circuit, 106 ... Pretreatment device, 107 ... Scan gantry, 109 ... High voltage generator, 110 ... host controller, 111 ... tomographic image data generator, 112 ... Reconfiguring device, 113 ... 3D model generator, 114 ... Reconfiguring device, 115 ... Input device, 116 ... Display device, 117 ... azimuth marker generator, 118 ... Synthesizer.

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Claims (6)

[Claims] 1. A means for scanning a three-dimensional region of a subject with X-rays, a means for generating volume data based on projection data acquired by the scanning, and tomographic image data of an arbitrary cross section from the volume data. Means for generating, means for generating surface model data including a marker representing the position of the cross section from the volume data, means for generating orientation markers respectively corresponding to the tomographic image data and the surface model data, X-ray computed tomography, comprising: means for generating display data by combining the surface model data with the azimuth marker as an inset view on the tomographic image data; and means for displaying the display data. apparatus. 2. A means for scanning a three-dimensional region of a subject with X-rays, a means for generating volume data based on projection data acquired by the scanning, and tomographic image data of an arbitrary cross section from the volume data. Generating means, means for generating tomographic image data of predetermined two orthogonal cross sections including a marker indicating the position of the cross section from the volume data, and tomographic image data of the arbitrary cross section and tomographic image data of the two orthogonal cross sections. A unit for generating corresponding azimuth markers; a unit for synthesizing the tomographic image data of the arbitrary cross section with the tomographic image data of the two orthogonal cross sections as an inset view to generate display data; An X-ray computed tomography apparatus, comprising: a means for displaying data. 3. A means for scanning a three-dimensional region of a subject with X-rays, a means for generating volume data based on projection data acquired by the scanning, and tomographic image data of an arbitrary cross section from the volume data. Generating means, means for generating image data including a marker indicating the position of the cross section from the volume data, means for generating orientation markers corresponding to the tomographic image data and the image data, and the tomographic image An X-ray computed tomography apparatus comprising: a unit for generating display data by combining the image data with the orientation marker as an inset view on data, and a unit for displaying the display data. 4. A means for scanning a three-dimensional region of a subject with X-rays, a means for generating volume data based on projection data acquired by the scanning, and tomographic image data of an arbitrary cross section from the volume data. Generating means, means for generating three-dimensional image data including a marker indicating the position of the cross section from the volume data, and means for generating orientation markers respectively corresponding to the tomographic image data and the three-dimensional image data. An X-ray comprising: a unit that synthesizes the three-dimensional image data with the orientation marker as an inset view on the tomographic image data to generate display data; and a unit that displays the display data. Computer tomography equipment. 5. An X-ray computed tomography apparatus for generating volume data based on projection data obtained by scanning a three-dimensional region of a subject with X-rays and generating tomographic image data of an arbitrary cross section from the volume data. In the X-ray computed tomography apparatus, the image data for inset view for representing the position of the cross section is generated from the volume data used for generating the tomographic image data. 6. An image processing apparatus for generating tomographic image data of an arbitrary cross section from volume data relating to a three-dimensional region of a subject, wherein the position of the cross section is represented from the volume data used for generating the tomographic image data. An image processing device for generating image data for inset view.