JPH03133432A - X-ray ct scanner - Google Patents

Abstract

PURPOSE:To reduce a partial volume artifact and to improve the picture quality by providing a data grouping means for dividing scan data of a 360 deg. portion into two or more groups, and an image reconstitution arithmetic means for obtaining separately image data with regard to each group. CONSTITUTION:When the scan data of scan angles 0 deg.-360 deg. in inputted, the data distributing part 11 of an image reconstituting device 4 divides it into two groups, and inputs one and the other to a first pre-processing part 12 side and a second preprocessing part 13 side, respectively. The scan angle of a boundary for grouping can be designated arbitrarily, and the data distributing part 11 executes grouping by overlapping the scan data before and behind the scan angle of the designated boundary. A first pre-processing part 12 and a first reconstituting part 14, and a second pre-processing part 13 and a second reconstituting part 15 execute the pre-processing of the scan data of a first group and the scan data of a second group, respectively, and execute an image reconstitution operation. An image synthesizing part 16 adds image data outputted from the reconstituting parts 14, 15, and synthesizes them to one image data.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an X-ray CT scanner, and more particularly to an X1CT scanner that reduces partial volume artifacts and improves image quality.

[Prior Art] As shown in FIG. 1, an XIICT scanner basically consists of a scanner device, a system control device, an image reconstruction device, two image display devices, and an image storage device. .

As shown in FIG. 7, the image reconstruction device in the conventional X@CT scanner includes a preprocessing section 62, a reconstruction section 64,
It consists of a post-processing section 67.

360° scan data around the subject obtained by the scanner device is preprocessed by a preprocessing unit 62, and then sent to a reconstruction unit 64.
The data is reconstructed and subjected to post-processing in the post-processing section 67 to become image data.

FIG. 8(a) is a conceptual diagram showing the relationship between the source fan S and the object O when the scan angle is 0°, and FIG. 8(b) is a conceptual diagram showing the relationship between the two as seen from the α direction in (a). It is a conceptual diagram. P
, Q are bones, for example. C is the rotation center of the source fan S, around which the source fan S rotates counterclockwise.
Change the scan angle from 09 to 3601.

FIGS. 9(a) and 9(b) are views corresponding to FIGS. 8(a) and (b) when the scan angle is 180°.

[Problems to be Solved by the Invention] In FIGS. 8 and 9, the bone P of the subject 0 has a scan angle of 1 even when the scan angle is O" (FIG. 8).
Even when the angle is 80° (FIG. 9), it is included in the source fan S and is suitably imaged by image reconstruction calculation.

However, if we focus on bone Q, the scan angle is O.

(Figure 8), it is not included in the source fan S,
At a scan angle of 180° (Fig. 9), the source fan S
included in. In this case, there is a problem that a contradiction occurs in the scan data regarding the presence of the bone Q, and a partial volume artifact occurs in the image obtained by image reconstruction calculation.

Such partial volume artifacts are likely to occur, for example, in areas with intricate bones, such as the base of the head and brain (forester fossa).

Therefore, an object of the present invention is to provide an X-ray CT scanner that can reduce the above-mentioned partial volume artifacts and improve image quality.

[Means for Solving the Problems] The X-ray CT scanner of the present invention can scan 360 degrees around the subject.
In an X-ray CT scanner that obtains image data by performing an image reconstruction operation on scan data of The configuration includes an image reconstruction calculation means for performing a reconstruction calculation to obtain image data respectively, and an image data synthesis means for synthesizing image data for each of the two or more groups to form one image data. This is the characteristic of

[Operation] In the X1sCT scanner of the present invention, scan data is divided into groups, and image reconstruction calculations are performed separately for each group.

Therefore, if data that are consistent or have little contradiction are placed in the same group, and data that is highly inconsistent is divided into another group, the image data obtained by image reconstruction calculations will be free of partial volume artifacts. Alternatively, partial volume artifacts may be reduced.

If such image data is combined into one image data, partial volume artifacts are suppressed, and since 360° scan data is used as a whole, the image quality is also good.

[Example] Hereinafter, the present invention will be described in more detail based on the example shown in the drawings. Note that this invention is not limited to this.

An X-ray CT scanner 1 according to an embodiment of the present invention shown in FIG.
are a scanner device 2, a system control device 3, an image reconstruction device 4, and an image display device 5.

The image storage device 6 is basically configured to include an image storage device 6.

Each of these components, except for the image reconstruction device 4, are the same as conventionally known components.

As shown in FIG. 2, the image reconstruction device 4 includes a data distribution section 11, a first preprocessing section 12, a second preprocessing section 13,
It includes a first reconstruction section 14, a second reconstruction plane section 15, a one-image composition section 16, and a post-processing section 17.

When the scan data of the scan angle 0° to 360° is manually input, the data distribution unit 11 divides the data into two groups, inputs one group to the first preprocessing unit 12,
Other groups are input to the second preprocessing section 13 side.

The scanning angle of the grouping boundary can be specified arbitrarily.
The data distribution unit 11 groups the scan data by overlapping them before and after the scan angle of the designated boundary.

For example, if you specify the boundary scan angle as 90',
Since the number of groups is two, the data distribution unit 11 basically divides the data into two groups of 180° each. Since the scanning angle of the boundary is 90°, the front and back sides thereof are overlapped by, for example, 10', and the first group is 80 (=90'-10°) to 280 @ (=
The scan data is 90@+180°+10', and the second group is 0° to 100'(=90°-10').
0) and 260@ (=90"+180' -10
1) Scan data in the combined range of ~360°.

3, 4, 5, and 6 show scan angle o'
, so°, 100′, and 180°, respectively. FIG. The source fan S rotates counterclockwise around the rotation center C to obtain scan data of 0° to 360°. In addition, 18
The relationship between the source fan S and the subject 0 from 0'' to 3600 is the same as that shown in FIGS. 3 to 6, so illustration thereof is omitted.

The first preprocessing unit 12 and the first reconstruction unit 14
Perform preprocessing and image reconstruction calculations on the group of scan data. This first group of scan data is from 80° to 18° from Figure 4 through Figure 5 to Figure 6.
Scan data at 0° and similar 180°
~280° scan data. As can be understood from the figure, there is no discrepancy in the data regarding bone P of subject O, and there is a slight discrepancy in the data regarding bone Q, but at scan angles of 0° (Fig. 3) and 180° ( Figure 6)
The contradiction between them is not a big contradiction.

Therefore, in the image data output by the first reconstruction unit 14,
Partial volume artifacts are reduced.

On the other hand, the second preprocessing unit 13 and the second reconstruction unit 15 preprocess the second group of scan data and perform image reconstruction calculations. The second group of scan data is
O°~100” from the state shown in the figure to Fig. 4 and to Fig. 6
Scan data and similar 260° to 3
This is 60° scan data. As can be understood from the figure, there is no discrepancy in the data regarding the bone P of the subject O, and there is only a slight discrepancy regarding the bone Q. However, 0° (3rd
It is not a big contradiction like between 180° (Fig. 6) and 180° (Fig. 6). Therefore, the image data output by the second reconstruction unit 15 has fewer partial volume artifacts.

The image synthesis section 16 adds the image data output by the first reconstruction section 14 and the image data output from the second reconstruction section 15, and synthesizes them into one image data.

The post-processing unit 17 post-processes the combined single image data and outputs it as image data.

The image data obtained here is 0~360 as a whole.
Since it was obtained using the scan data of °,
Good image quality. On the other hand, discrepancies between scan data are
Since image reconstruction calculations are performed separately for two groups, one group consisting of data with less contradiction, partial volume artifacts are reduced.

Note that the part that performs preprocessing and image reconstruction calculations for each group of scan data can be configured as a node, and in this case, the calculations will be performed in parallel.
This has the effect of shortening processing time.

It can also be configured software-wise; in this case, changing the grouping (number of groups).

This makes it easy to change the boundaries, so if you change the designation appropriately depending on the part of the subject, you can always obtain the optimal image.

[Effects of the Invention] According to the X-ray CT scanner of the present invention, mutual inconsistency in data used for image reconstruction calculations can be reduced, so partial volume artifacts can be reduced. Furthermore, since 360° scan data is used as a whole, it is possible to obtain good image quality.

[Brief explanation of the drawing]

FIG. 1 is a basic block diagram of an XBCT scanner according to an embodiment of the present invention, FIG. 2 is a block diagram of an image reconstruction device in the embodiment shown in FIG. 1, and FIG. 3(a) is a scan angle of 0°. A conceptual diagram showing the relationship between the source fan and the subject when
Fig. 4(a) is a conceptual diagram showing the relationship between the source fan and the subject when the scan angle is 80°, Fig. 4(b) is a view along the α arrow in Fig. 4(a), and Fig. 5(a) ) is a conceptual diagram showing the relationship between the source fan and the subject at a scan angle of 100°, FIG. 5(b) is a view taken along the α arrow in FIG. 5(a),
FIG. 6(a) is a conceptual diagram showing the relationship between the source fan and the subject at a scan angle of 1808, and FIG.
7 is a block diagram of a conventional image reconstruction device; FIG. 8(a) is a conceptual diagram showing the relationship between the source fan and the subject when the scan angle is 0°; 8th
Figure (b) is the α arrow view in Figure 8 (a), Figure 9 (a
) is a conceptual diagram showing the relationship between the source fan and the subject at a scan angle of 180°, and FIG. 9(b) is a view taken along the α arrow in FIG. 9(a). (Explanation of symbols) 1...X1CT scanner 4...Image reconstruction device 11...Data distribution section 12...First preprocessing section 13...Second preprocessing section 4...First Reconstruction unit 5...Second reconstruction unit 6...Image synthesis unit 7...Post-processing unit S...Source fan 0...Subject C...Rotation center.

Claims (1)

[Claims] 1. In an X-ray CT scanner that obtains image data by performing image reconstruction calculations on scan data of 360 degrees around a subject, data grouping that divides 360 degrees of scan data into two or more groups. means for separately performing image reconstruction calculations on each of the two or more groups to obtain image data, and combining the image data for each of the two or more groups into one image data. An X-ray CT scanner characterized by comprising: image data synthesis means.