JPS6363434A - X-ray ct apparatus - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an X-ray CT apparatus, and particularly to an X-ray CT apparatus suitable for positioning using a fluoroscopic image.

[Conventional technology]

Xl&! A 1lcT device has a function of obtaining a tomographic image of a subject. Some X-ray CT devices have a function of obtaining not only a tomographic image but also a fluoroscopic image. The fluoroscopic image itself is used as diagnostic information, but it is also often used to identify the area from which a CT tomographic image is obtained.

That is, first, the subject is moved and a fluoroscopic image is obtained.

Next, this perspective image is displayed as a screen. A cutting position for obtaining a CTFIR layer image is specified by specifying an arbitrary position on the fluoroscopic image on the screen. The designated position is then displayed as a single straight line on the screen.

[Problem that the invention seeks to solve]

In this conventional example, the cutting position is indicated by one straight line in the fluoroscopic image. Here, the slice width (cutting width) of the XaCT device is lllff11 to 10 mm, and the size of one pixel of the display device that displays the fluoroscopic image is 0.5I to 1
It is mm. Therefore, one straight line in a perspective image is 0.
It is displayed with a width of 5 m to II, and the slice width is 1
The object of the present invention is to provide C which can display the slice width accurately.
The present invention provides a T-section device.

[Means for solving problems]

The present invention specifies the center position of cutting, determines the slice width with respect to this center position, converts the center position and slice width into an address on the display screen of the perspective image, and superimposes the cut on the perspective image according to this address. It was decided to display the position and the position of the slice width around the position.

[Effect]

The tomographic center position (or the tomographic center position and slice width) is input from the outside, and from this information it is possible to automatically display the position of the slice width at which the tomographic image is obtained by superimposing it on the fluoroscopic image.

〔Example〕

FIG. 1 shows an embodiment of the CT apparatus of the present invention.

X-ray source 1 is installed at opposite positions across the measurement space of the rotating frame IA.
．． An X-ray detector 2 is provided. The X-ray source 1 is a fan-shaped X-ray source,
The X-ray detector 2 is a multi-channel detector.

Bed 3 is movable in the direction of the arrow, and a subject is mounted on it. The movement of the bed 3 is controlled by a control circuit 9.

The computer 4 takes in the transmitted X-ray detection values of the multi-channel X-ray detector 2 and obtains a fluoroscopic image and an X-ray CT image.

First, a fluoroscopic image is obtained, and after this fluoroscopic image is displayed on the display device 6, the slice width is displayed, and then a CT tomographic image is obtained.

The memory 5 stores fluoroscopic images and X-ray CT images.

The display bag M6 displays the contents of the memory 5.

The input device 7 specifies the cutting center position and slice width.

The position calculation device 8 takes in the cutting center position and slice width inputted from the input device 7 and executes a process of converting them into an address on the display screen 1, and a process of creating a control command to the control circuit 9.

The input device 7 also inputs the perspective position.

The process of obtaining a perspective image is as follows.

(i) Place the subject on the bed.

(ii) Input the perspective position from the input device 7.

(iii) The position calculation circuit 8 obtains the moving distance (while moving) of the bed from the perspective position, and controls the bed 3 to move (forward or backward) by the width of this moving distance. In this movement control, the bed 3 is positioned at a starting position in advance.

(Gloss) The bed 3 is moved in predetermined pitch units.

An X-ray source 1 emits X-rays at each pitch position, and an XM detector 2 receives transmitted X-rays from the subject.

(v) The computer 4 takes in the detection value of the X-ray detector 2,
Perform perspective image data processing to obtain perspective image data. The perspective image data is stored in the memory 5.

(vi) The display device 6 reads out the perspective image data in the memory S using the rask scan method and displays it once.

The process of obtaining a CT tomogram is as follows.

(i) Place the subject on the bed.

(it) A CT tomographic region is specified by an instruction from the control device 9, and the bed 3 moves to the specified position with the subject placed thereon.

(■) When the designated position is reached, the bed 3 is fixed. Then, while rotating the frame IA, the Xla source 1 irradiates X-rays at predetermined pitches.

(tv) The X-ray detector 2 detects transmitted X-rays at each pitch position.

CV) Calculator 4 is Xi! The detected values of the detector 2 are taken in, and the image is re-terminated to obtain cTvIR layer image data. This CT tomographic image data is stored in the memory S, and the display device 1 reads it out to display the CT tomographic image on the screen.

In the above description, when obtaining a fluoroscopic image, the X-ray source 1 and the X-ray detector 2 are fixed, but it is also possible to move them within a certain range to obtain a fluoroscopic image over a wide range.

A display example of a perspective image is shown in FIG. 2, and this perspective image is of a human chest. Regarding a perspective image, consider the X-Y coordinate axes as shown in the figure. The number of pixels in the horizontal direction (X direction) is m, and the number of pixels in the vertical direction (Y direction) is n. These m×n pixels constitute one screen.

This perspective image is stored in the memory 5, and is read out from the memory 5 and displayed on the display device 6. An example of storing perspective images in the memory 5 is shown in FIG. Memory 5 has 1
The perspective data is stored in the order of row, second row, . . . , n-th row. Each row consists of m addresses. For example, for the first line, addresses 0, 1, 2. ...2m-1 is allocated, and each address has corresponding perspective data D,,D
Yo, D.

..., D,-, are stored. The same goes for other lines.

Here, the perspective data D+ (however, l ” Or 1 +
2, ..., m-n-1) is binary data (“1” or 1
40") or multi-value data (gradation data).

Now, in this embodiment, the fluoroscopic image displayed on the display device 6 is used for positioning when obtaining the above-mentioned CT tomographic image. For this purpose, a predetermined instruction was given from the input device 7, a predetermined process was performed according to the instruction, and a predetermined display was made on the display device 6.

Further, it will be explained in detail.

The slice center bed position P and slice width S are given by the input device 7. What is slice center bed position Hp?
Since the tomographic image has a constant slice width, the purpose was to identify one point, and the central point of the slice width was used to identify it. For example, the coordinate value y3 in the Y direction in FIG. 2 is designated as the Y coordinate corresponding to the slice center bed position.

The slice width S is the tomographic width of a tomographic image. It refers to the width S sandwiching the central bed position P. The slice width S is disclosed in FIG. The slice width S is indicated by the width in the Y direction on the display screen.

Center bed position P and slice width S specified by input device 7
The display position calculation device 8 performs processing to display the tomographic region superimposed on the perspective image on the display screen of the display device 6. This processing consists of the following processing.

(i) Creating a tomographic region on the display screen from the central bed position P and slice ils. That is, in FIG. 2, a line segment A passing through the center position P and parallel to the X direction is created,
In addition, line segments B and C parallel to the X direction are created at positions with a slice width S that sandwich this central bed position P. Here, line segment A is a solid line, and line segments B and C are dotted lines.

(ii) The data regarding the created line segments A, B, and C are sent to the memory 5 and temporarily stored.Then, the display device 6 reads this data and displays it as shown in FIG.

(in) Center bed position [P and slice width S are used for positioning the bed 3. For this purpose, the data is processed into control data, and the bed 3 is positioned via the control device 9.

A specific example of the display position calculation device 8 described above is shown in FIG. The display position calculation device 8 includes a center display position calculation section 81. Slice range display calculation unit 82. Slice range data generation unit 83
．． Memory control unit 84. It consists of a bed position calculation section 85.

(i) Center display position calculation unit 81... Center target position y on the Y coordinate corresponding to the slice center bed position
When s is specified, the starting address a of the line segment A including the position rll y s in the memory 5 is calculated using the following formula.

a= (ys 1)・m (1)
However, (1≦ys≦n) (ii) Slice range display calculation unit 82...
When the slice width S is specified, the starting addresses of the upper and lower line segments B and C corresponding to the slice range on the memory 5 are specified.

Calculate C according to the following formula.

First, the position of line segment B in the y direction is determined using the following equation.

However, j is the length of one pixel, and the unit is (m). Next, from equation (2), similarly to equation (1), the starting address of line segment B is determined using the following equation.

b= (yb 1)m = (ysl)・m−s・(m/2j) =a−s・(m/2j) ・・・・・・(3) Here, a=(ysl)・m It is. However, when b≦0, b=o.

Furthermore, C can be similarly determined by the following equation.

c == 6 + 8 conflict (m / 2 j)
・・・・・・ (4) However, C≧(n −1)・
When m, it is assumed to be c(n-1)m.

(Quick) Slice range data generation section 83...
Specify the color of the line segments in which the tomographic regions A, B, and C are to be displayed, nine types of 'a'a (distinctions between solid lines, two-dot lines, etc.), etc. An example of this is shown in FIG. Figure 5 (a) is the display data for the center position line segment A, and all 1m addresses are displayed in white.
This is an example. Figure 5 (b) shows display data for line segments B and C, with white display data W in units of three addresses.
and black display data B are repeated. In addition, the first address in FIG. 5(a) is actually a in equation (1), the fifth address.
The starting address in figure (b) actually corresponds to s and c in equations (3) and (4). This replacement with a, b, and Q is performed by the control unit 8.
4 will do it.

In addition to white and black, there may also be examples of shading.

(iv) Memory control unit 84...Calculation unit 81
．． The procedure for sequentially writing the data of the generating section 83 into the memory 5 using the address obtained in step 82 is as follows.

First, the content of the slice range display data at address 0 is written to memory address 50 obtained by the calculation unit 82.
1 of the slice range display data with the address of (b+1)
Write the contents of the address, sequentially 2nd address..., (m
-1) Write the address on the same line. The same applies to address C.

Next, the content of the center position display data at address 0 is written to address a of the memory 5 determined by the calculation unit 81. Similarly, memory 5
The contents of address 1 of the center position display data are written to address (a+1).

Thereafter, center position display data is written into the memory 5 in the same manner.

Thus, the data of line segments a, b, and c of the sliced region are stored in the memory 5 superimposed on the fluoroscopic image.When displaying data, the contents are read one after another while raster scanning the memory 5. 2 to the display device 6 for display. The displayed contents are as shown in FIG.

(v) Bed position calculation unit 85: Calculate the slice center bed position of the bed 3 from the coordinate position yS using the following formula.

P”Po (ya ys)・j ・・・・・・(
5) Here, as shown in FIG. 2, ya is the end reference position in the Y-coordinate direction of the perspective image [tpo is the bed position. (5
) From the formula, the distance p from the reference position to the slice center position,
-p is Pa-P=Cyo-ys)・j...(6
), and the amount of movement from the reference position (yo-ys)・
j is given to the control device 9, which calculates the actual amount of movement and positions the bed 3 based on this amount of movement and the amount of deviation from the current reference position of the ped 30. After this positioning is completed, the operation procedure (including the processing procedure) for obtaining a CT tomographic image has been described above.

According to this embodiment, when performing positioning, not only the center position but also the photographing range is displayed at the same time, so that effective positioning can be performed while taking the photographing range into consideration.

Furthermore, in addition to the solid 9-dot line, there are various display modes (colors, etc.).

This allows the slice width to be accurately confirmed. Also, the display range is not the entire screen,
By giving the starting coordinate position and the ending coordinate position to the control section 84 in advance, it is possible to freely select the starting coordinate position and the ending coordinate position.

In this embodiment, the center position and slice width are specified. If the slice width S is the same for any tomographic region, it may be a fixed value, but when changing the slice width depending on the tomographic region, it is necessary to change the slice width S depending on the center position. When determining the slice width, it is determined based on the amount of transmission and the viewpoint of eliminating unnecessary exposure.

〔Effect of the invention〕

According to the present invention, the imaging range when obtaining a CT image can be accurately known in advance from a fluoroscopic image.

Furthermore, it became possible to accurately determine the target position and obtain a highly accurate CT tomographic image.

[Brief explanation of the drawing]

1 is an embodiment of the present invention, FIG. 2 is an example of a perspective image display, FIG. 3 is a view of the data storage side of the memory 5, FIG. 4 is an embodiment of the position calculation device, and FIG. stomach). (b) is an example diagram of slice area display data. IA...Rotating frame, 1...X-ray source, 2...X
Line detector, 3... bed, 4... calculator, 6...
Display device, 7... input device. Patent Applicant Tadashi Akimoto Patent Attorney Hitachi Medico Co., Ltd. Figure 1 Figure 2 Figure 4

Claims (1)

[Claims] 1. A rotating frame having an X-ray source and an X-ray detector placed opposite to each other across a measurement space, a bed for mounting a subject that is movable in the measurement space of the rotating frame, and a CT tomographic image. A first means for obtaining a fluoroscopic image from the detection value of an X-ray detector that transmits through the subject prior to obtaining the fluoroscopic image, a memory for storing the fluoroscopic image, and a display device for displaying the contents of the memory; means for displaying a CT slice center position and slice width on a display screen of a display device according to external specifications;
An X-ray CT apparatus comprising means for specifying a tomographic position and obtaining a CT tomographic image from detected values of the X-ray detector.