JPH04250144A - X-ray ct pulmonary field photographing system - Google Patents

Abstract

PURPOSE:To easily provide a scanning plan within a short time. CONSTITUTION:In a X-ray CT pulmonary field photographing system for conducting the scanning to a subject P according to a scanning plan formed to a scanner image in which the pulmonary field of the subject P, a profile extracting means 12 for extracting the profile of the lung to the scanner image to set the upper and lower limits of the pulmonary filed and a scanning plan making means 13 for making the scanning plan on the basis of the upper and lower limits of the pulmonary filed and profile of the lung obtained by the profile extracting means 12 are provided.

Description

[Detailed description of the invention]

[Object of the invention]

0002

[Industrial Application Field] The present invention is installed in an X-ray CT apparatus, automatically creates a scan plan from a scanogram of a subject's lung field, and scans the subject's lung field according to this scan plan. The present invention relates to a lung field imaging system for X-ray CT.

0003

[Prior Art] An X-ray CT apparatus scans a subject to obtain tomographic images (slice images) of a plurality of slice planes perpendicular to the body axis of the subject. In order to determine this, a scan image of the subject is obtained in advance and a scan plan is created. For example, when photographing the lung field of a subject, after obtaining a scanogram 100 of the lung field as shown in FIG. Upper limit 101, lower limit 102
is set to determine the slice positions 104a to 104j.

[0004] After this, in the scanner section of the X-ray CT apparatus,
According to the above scan plan, the lung field of the subject is scanned at slice positions 104a to 104j to obtain slice images of these slices.

[0005]

[Problems to be Solved by the Invention] However, in the case of the above-mentioned prior art, the operator judges the outline of the lung from the scanogram and sets the upper and lower limits of the lung field to plan the scan. This method has the drawbacks of being time consuming and placing a heavy burden on the operator.

The present invention has been made to solve the problems of the prior art described above, and its purpose is to provide an X-ray C method that can easily obtain a scan plan in a short time.
An object of the present invention is to provide a lung field imaging system for T.

[Configuration of the invention]

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention scans a subject according to a scan plan created for a scanogram of the lung field of the subject. In the lung field imaging system for X-ray CT, a contour extraction means extracts the contour of the lung from the scanogram and sets an upper limit and a lower limit of the lung field; an upper limit of the lung field obtained by the contour extraction means; The present invention is characterized by comprising scan plan creation means for creating a scan plan based on the lower limit and the contour of the lung.

[0009]

[Operation] In the lung field imaging system for X-ray CT of the present invention having the above configuration, when a scanogram of the lung field of the subject is obtained, the contour extraction means extracts the contour of the lung from the contrast etc. of this scanogram. and set the upper and lower limits of the lung field.
The scan plan creation means creates a scan plan based on the upper and lower limits of the lung field and the outline of the lungs, so when an X-ray CT device equipped with this system takes a scanogram, it automatically You can create scan plans automatically. Therefore, a scan plan can be easily obtained in a short time, and the burden on the operator is reduced.

0010

[Embodiments] Hereinafter, embodiments of the present invention will be explained based on the drawings. FIG. 1 is a block diagram showing the configuration of an X-ray CT apparatus equipped with an X-ray CT lung field system according to an embodiment of the present invention. In the figure, this X-ray CT apparatus 1 has an approximate object P.
a scanner unit 2 for scanning and photographing;
An information processing unit 3 for reconstructing an image based on the image information obtained by the scanner unit 2; and a display unit 4 such as a CRT display for displaying the reconstructed captured image of the subject P. It consists of

In the scanner section 2, an X-ray tube 5 and a detector 6 are disposed facing each other in a pedestal (not shown). At the time of scanning, the subject P placed on the top plate 7 of a bed (not shown) is placed in the imaging hole of the pedestal, and the X-ray tube 5 and detector 6 rotate around the subject P to perform the scan. , X-rays emitted from the X-ray tube 5 and transmitted through the subject P are detected by the detector 6. The information regarding the X-ray absorption coefficient of the subject P obtained by the detector 6 is sent to the DAS (data acquisition unit) as an electrical signal.
8 to the information processing section 3.

The information processing unit 3 includes an image reconstruction unit 10 that reconstructs a slice image of the subject P based on the signals sent from the scanner unit 2, and a scanner unit that forms a scanogram of the subject P. An image forming means 11, a contour extracting means 12 and a scan plan creating means 13 for creating a scan plan for the scano image are provided.

The contour extracting means 12 extracts the contour of the lung using the image data of the scanogram of the subject P formed by the scanogram forming means 11, and extracts the contour of the lung. Set upper and lower limits. The scan plan creation means 13 creates a scan plan similar to the conventional example shown in FIG. 7 based on the obtained upper and lower limits of the lung field and the contour of the lung. The scanner unit 2 scans the subject P according to this scan plan.

Next, the X-ray CT apparatus 1 examines the subject P.
The operation when photographing the lung field will be explained using FIG. 2.

First, before scanning the subject P, the lung field of the subject P is photographed in order to obtain a scanogram, and the detection data obtained by the detector 6 at this time is sent to the scanogram via the DAS 8. The scan image forming means 11 forms a scan image of the lung field of the subject P based on the sent data (step 1). This scanogram is displayed on the display means 4. Next, the contour extraction means 12 extracts the body surface (step 2), the lung contour (step 3), and sets the upper and lower limits of the lung field (step 4) on this scanogram.

The operation of the contour extracting means 12 at this time will be explained in detail.

First, for a scanogram 20 as shown in FIG. 3, the image data (profile) of this image is compared with the threshold value of the inside of the body and the air, and the body surface 21 is extracted. For example, the profile on the straight line l in the scanogram 20 is as shown in FIG. 4, and the dotted line portions 22a and 22b in FIG. 4 correspond to the body surface portions 21a and 21b, respectively.

Next, the outline 23 of the lung region 22 is extracted. In the scanogram 20 of the lung field, the lung part 22 is darker than other parts and has a lower CT value, and near the outline 23 of the lung part 22, there is a part where the ribs overlap, which is whiter than other parts and has a lower CT value. Since there is a high part 24, the scanogram 20
The contour 23 of the lung region 22 can be determined from the contrast. Note that the central portion 25 of the scanogram 20 is not particularly necessary for creating a scan plan for the lung field, and will be ignored. Explaining using the profile shown in FIG. 4, the central part 25a is the data part to be ignored, and the highest points 24a and 24b are the white parts 24 described above.
This is the data.

To explain in detail the contour extraction operation of the right half of the lung 22, first, the minimum value of the profile of the body part is found. Since the profile value of the lung part 22 is lower than that of other parts, the point A0 of this minimum value should be within the lung part 22. If the x-axis and y-axis are taken in the direction shown in Figure 3, and the coordinates of point A0 in this coordinate system are (a0, b0), then point A1 (a0 +d,b0) centered at 10
Find the average value and median value within a square area of ×10 pixels. Compare this average value and median value, and the average value is point A.
0, and if the median value and the average value are approximately equal, point A2 (a0 + 2d , b0 ) in a 10×10 pixel square area, and perform the same comparison as above.

In this way, the average value and median value within a 10×10 pixel area from point A0 to the right in FIG. Or, when the difference between the median value and the average value is greater than a certain level, the maximum value of the profile in this square area is determined. This maximum value point Am
ax (an, b0) is within the white part 24 of the scanogram 20 and near the lung contour 23, and this point Amax is regarded as a point on the lung contour 23 (hereinafter referred to as an edge point). .

Next, the right side (
The average value within a 10x10 pixel area centered on point A' (an +10,b0) on the body surface 21 side) and the point Am
Point A” (an
-10,b0) and the average value within a 10x10 pixel area centered on Amax, and if the two are approximately equal, the edge point determination is canceled and this point Amax is not considered as an edge point. This point Amax is regarded as an edge point only if the average value on the right side is larger than the average value on the left side. Then, (an, b0) is stored as the coordinates of the edge point.

Next, in a 10×10 pixel area centered on a point Am (am, b0 +10), which is moved 10 pixels upward (in the positive direction of the y-axis) from the center point of the square area where the edge point Amax was obtained, The average value and median value are determined, and edge points on the straight line of this y coordinate are determined in the same manner as above. However, if the edge point obtained at this time is closer to the body surface 21 than the edge point Amax (an, b0), this edge point is canceled based on the shape of the lung 22. Similarly, edge points are found one after another in the positive direction of the y-axis, and the last edge point Au (au, bu) when reaching the center portion 25 is set as the upper limit in the right half of the lung portion 22. Here, the edges obtained as described above are obtained as a plurality of line segments 23a as shown in FIG. 5, and these line segments 23a are connected into one curve to form the outline of the lung region.

Edges below the point Am (am, b0) are found by the same operation as above, but for the lower limit, the edge point Ad (a
d , bd ), a point 10 pixels below Ac (ad
, bd-10), the point Ar 10 pixels to the right
Average value in a 10x10 pixel area centered on (ad+10, bd-10) and point A 10 pixels to the left
10×1 centered on l (ad-10, bd-10)
The average value in the 0 pixel area is calculated, and when the average value on the right side and the average value on the left side are almost equal, the above point Ad (ad
, bd) is the lower limit in the right half of the lung part 22.

Extracting the outline of the left half of the lung part 22 and setting the upper and lower limits are performed in the same manner as above, and by comparing the obtained upper limit of the right half and the upper limit of the left half, the one with the larger y-coordinate is selected. The upper limit is the upper limit of the entire lung portion 22. Similarly, regarding the lower limit, the lower limit with the smaller y coordinate is set as the lower limit of the entire lung portion 22. The outline of the lung part 22 extracted in this way, the set upper limit line (a straight line that includes the upper limit and is parallel to the x-axis), and the lower limit line (a straight line that includes the above lower limit and is parallel to the x-axis) are displayed on the display means. 4 together with the scanogram 20.

As shown in FIG. 6, when the scanogram 20, the outline 23b of the body surface 21 and lung region obtained by the outline extracting means 12, the upper limit line l1, and the lower limit line l2 are displayed on the display means 4, The scan plan creation means 13 creates an upper limit line l1 and a lower limit line l2 of the lung field with respect to the scanogram 20.
Then, a scan plan is created based on the lung contour 23b (step 5). That is, the slice position 26 is divided by the slice thickness between the upper limit line l1 and the lower limit line l2.
Determine a to 26j. This slice position 26a-26
j is displayed on the display means 4 (step 6).

The operator then looks at the displayed scan plan (step 7), and if there is no problem, instructs the apparatus to continue imaging the subject P. That is,
The top plate 7 on which the subject P is placed is moved and installed at a predetermined position (step 8), scan conditions are set in the scanner section 2 (step 9), and a predetermined slice position is scanned for the subject P. is performed (step 10)
). If the scan plan has not yet been completed when the scan of this slice position is completed (there is a slice position that has not been scanned) (step 11), s
Returning to step 6, the next slice position is scanned in the same manner as above. In this way, the slice positions 26a~
When all the areas 26j have been scanned, the scan plan ends (step 11), and the imaging of the subject P ends. If there is a problem with the scan plan in step 7, the process returns to step 5 and an appropriate scan plan is created again.

As described above, in this embodiment, when the scanogram 20 is obtained, a scan plan is automatically created by the contour extraction means 12 and the scan plan creation means 13, so that scanning can be performed easily and in a short time. plan is obtained,
The burden on the operator is reduced.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and various modifications can be made.

[0029]

Effects of the Invention The X-ray CT lung field imaging system of the present invention has the above-described configuration and function, and can easily, quickly, and automatically plan a scan for a scan image of a subject's lung field. can be created to reduce the burden on the operator. In an X-ray CT device equipped with this system, a scan plan is automatically created when a scanogram is obtained, and the lung field of the subject is scanned in accordance with this scan plan. It is possible to photograph the subject.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an X-ray CT apparatus equipped with an X-ray CT lung field imaging system according to an embodiment of the present invention.

FIG. 2 is a flowchart showing scan plan creation and imaging operations in the same embodiment.

FIG. 3 is a diagram showing a scanogram obtained in the same example.

FIG. 4 is a diagram showing a profile on a predetermined straight line in the same scanogram.

FIG. 5 is an explanatory diagram showing a line segment portion of an edge obtained by the contour extraction means in the same embodiment.

FIG. 6 is an explanatory diagram showing a scan plan created in the same example.

FIG. 7 is an explanatory diagram showing a scan plan in a conventional example.

[Explanation of symbols]

1. X-ray CT device 12 Contour extraction means 13 Scan plan creation means 20 Scanno statue 23, 23b Outline of the lungs l1 Upper limit line l2 Lower limit line P Subject

Claims (1)

[Claims] 1. In an X-ray CT lung field imaging system that scans a subject according to a scan plan created for a scanogram of the lung field of a subject, a contour extraction means for extracting the contour and setting upper and lower limits of the lung field; and a scan plan creation means for creating a scan plan based on the upper and lower limits of the lung field and the lung contour obtained by the contour extraction means. A lung field imaging system for X-ray CT, comprising: