JPH11104120A - Computerized x-ray tomography imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray computerized tomography imaging device capable of performing correct scanning by only specifying an scanning area and required image thickness. SOLUTION: Based on a specified scanning area and required image thickness, this device automatically determines at least either a basic slice thickness or the number of row of detectors. For example, when a user specifies a scanning area as 40 mm, slice thickness as 10 mm, the scanning area is automatically divided into five parts, scanning is performed, and four images are displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention A multi-slice detector having detectors divided into a plurality of rows in the body axis direction is provided, a conventional scan is performed without moving a couch during the acquisition of projection data, and the acquired projection data is used. X-ray computed tomography apparatus (CT) for reconstructing and displaying images.

[0002]

2. Description of the Related Art In a single slice CT having one row of detectors in the body axis direction, the basic slice thickness is determined by the width of an X-ray radiated to a subject. FIG. 7 is a diagram schematically showing such a single-slice CT system. The width of the X-ray which determines the basic slice thickness is controlled by a collimator called a slit placed between the X-ray tube and the subject. X-ray beams of various thicknesses can be obtained by opening and closing these slits according to the required slice thickness.
After passing through the subject, the line beam enters the detector. If this is collected as projection data and reconstructed,
An image with the required slice thickness can be obtained.

In a multi-slice CT having a plurality of rows of detectors in the body axis direction, the basic slice thickness is determined by the width of the detectors in the body axis direction. FIG. 2 shows a multi-slice C
It is a figure showing the concept of T system. Here, the width of the detector is fixed as a system and cannot be changed by the photographer, so the basic slice thickness is fixed. Also,
Because the number of detector rows that can be collected at one time is limited, one
There is a limit to the width over which projection data can be collected by rotation.

[0004]

When performing a conventional scan with a multi-slice CT having a fixed column width and a fixed number of columns, it may not be possible to reconstruct an image from a combination of data of one rotation depending on the thickness of the image. . In addition, when scanning is performed in a plurality of rotations, X-rays are irradiated to a region that does not need to be photographed, which may cause unnecessary exposure to the subject.

[0005] Further, when trying to reproduce the comparison of images and the data acquisition, there is a problem that the operator is confused because several kinds of basic slice widths of the detector can be selected even for images having the same slice thickness.

Accordingly, an object of the present invention is to provide an X-ray computed tomography apparatus capable of appropriately performing scanning only by a simple operation of designating a scan area and a required image thickness.

[0007]

In order to solve the above problems and achieve the object, an X-ray computed tomography apparatus of the present invention is configured as follows. (1) In an X-ray computed tomography apparatus that performs a multi-slice scan by a multi-slice detector in which a plurality of detector rows having a basic slice thickness are arranged, based on a designated scan area and a required image thickness, An X-ray computed tomography apparatus, comprising: control means for controlling at least one of a basic slice thickness and the number of detector rows. (2) The controller controls the basic slice thickness or the number of the detector rows so as to appropriately scan an area equal to the designated scan area.
2. The X-ray computed tomography apparatus according to claim 1. (3) When an image of a necessary thickness cannot be obtained by a combination of data obtained by one rotation of the detector row, based on a combination of the data and data collected by another rotation. The X-ray computed tomography apparatus according to claim 1, wherein an image is reconstructed. (4) When the data collected by each of the detector rows is used in a bundle in the body axis direction, a display pitch of an image in the body axis direction is made equal to the basic slice thickness. 2. The X-ray computed tomography apparatus according to 1. (5) The X-ray computed tomography apparatus according to claim 4, wherein the data bundling in the body axis direction is based on a new data difference. (6) The X-ray computed tomography apparatus according to claim 1, further comprising: means for displaying the basic slice thickness and the number of the detector rows in association with a display image.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 shows an X according to a first embodiment of the present invention.
FIG. 3 is a block diagram illustrating a schematic configuration of a line CT. As shown in the figure, the X-ray CT of the present embodiment includes an X-ray tube 1, an X-ray control
High-voltage generator 2, radiation detector 3, data collection device 4, data storage device 5, image reconstruction device 6, gantry / bed 7, gantry / bed drive control device 8, operation unit 9, image display unit 10, image Processing device 11, image storage device 12, CPU1
3.

The X-ray tube 1 irradiates an X-ray to a subject (not shown) under the control of the X-ray control / high voltage generator 2. The subject is placed on the gantry / bed 7. The radiation detector 3 detects transmitted X-rays transmitted through the subject. In addition,
The X-ray tube 1 and the radiation detector 3 are opposed to each other with the subject interposed therebetween, and are provided so as to be rotatable around the subject during scanning while maintaining the facing state. .

The data acquisition device 4 generates projection data of the subject based on the detector output from the radiation detector 3 and sends the data to the image reconstruction device 6. On the other hand, the projection data of the subject is stored and held by the data storage device 5.

The image reconstruction device 6 performs a predetermined reconstruction operation on the transmitted projection data, and thereby reconstructs a tomographic image at a predetermined slice position of the subject. The reconstructed tomographic image of the subject is stored in the image storage device 1
2 and the image processing device 11
Are subjected to predetermined image processing, and are displayed by the image display unit 10.

The operation section 9 is for giving a predetermined operation input from the operator to the apparatus via the CPU 13. In addition,
The CPU 13 controls the entire operation of the apparatus. FIG. 2 is a diagram for explaining the concept of multi-slice CT. As shown in the figure, the radiation detector 3 has a plurality of detection element rows in which a plurality of detection elements 31 are arranged along a circumferential direction (channel) in a body axis direction (segment).
It is constituted by being arranged.

FIG. 3 shows that the width of the detector in the body axis direction is 2 mm,
FIG. 9 is a diagram illustrating an example of scanning in a system having four columns.
The solid frame indicates the width over which data can be collected in one rotation. As an aid to understanding, the width of data collection by the even number of rotations is hatched. The dotted line is the slice thickness for one row. This indicates that data of a basic slice thickness of 2 mm can be collected for about four rows in one rotation. 40m
Scanning an area of m requires 5 rotations and 10
It can be seen that when reconstructing an image of mm, all four columns in the first rotation and data in the first column in the second rotation are used.

This embodiment is provided with means for controlling the number of detector rows and the number of rotations of the detectors based on the designated scan area and the required image thickness. For example, if the photographer specifies a scan area of 40 mm and a slice thickness of 10 mm, the scan area is automatically divided into five (40 mm /
10 mm), scanning is performed, and four images are displayed.

Here, the image slice thickness is 10 mm.
At the same time, it is desirable to indicate that the basic slice width of the detector when data is collected is 2 mm. That is, the same image slice thickness 1
Even if it is 0 mm, when collecting with a multi-slice detector, a plurality of conditions can be set, such as collecting a basic slice width of 2 mm × 5 rows or collecting a 1 mm × 10 rows. Therefore, in order to uniquely specify an image, conditions for collecting data are simultaneously displayed.

(Second Embodiment) Next, a second embodiment of the present invention will be described. FIG. 4 shows a scan area of 8 mm
FIG. 9 is a diagram illustrating a scan example when the number is not an integral multiple of (2 mm × 4 columns). 24m when collecting 3 rotation data in 4 rows
The data of the area m is collected, and the unnecessary area is exposed. Therefore, in the present embodiment, data of the last one rotation is automatically collected in two columns.

FIG. 5 is a diagram showing an example of an image display method according to the present embodiment. Since data is basically collected in units of 2 mm, even when an image with a thickness of 10 mm is displayed, it can be displayed at a pitch of 2 mm in the body axis direction, and more precise observation is possible. Further, if more precise observation is required, an image having a thickness of 8/6/4/2 mm can be displayed.

When data to be bundled in the first and second sheets overlaps as in this case, a difference is calculated for each of the preceding and succeeding sheets, instead of adding five new sheets. This can reduce the amount of calculation.

FIG. 6 is a flowchart showing the flow of the processing of the present apparatus when such precise observation is performed. First, scanogram imaging is performed in step S1, and the slice thickness is specified in step S2.
Here, any slice thickness of 2/4/6/8/10 mm can be designated. Next, in step S3, a scan area is specified. Here, a multiple of the basic slice thickness (2 mm in this example) can be specified.

Subsequently, in step S4, the slice thickness specified in step S2 is 2/4/6/8 m
m is determined (in other words, 10 mm is not specified), and if YES, the process from step S5 is performed, and if NO, step S6 is performed.
The following processing is performed.

First, in step S5, it is determined whether or not the scan area is within 8 mm, and the scan is executed. That is, if the scan area is within 8 mm, 1
Scanning is performed as one rotation (step S7) in / 2/3/4 rows, and if it is 8 mm or more, scanning is performed with a plurality of rotations (step S8) in rows corresponding to the slice thickness.

After performing either the scan in step S7 or step S8, in step S9, tomographic images corresponding to the specified number of slices are displayed. On the other hand, step S
In step 6, it is determined whether or not the scan area is a multiple of 8 mm, and the scan is executed. That is, when the scan area is a multiple of 8 mm, scanning is performed by rotating the detector array four times (step S10), and when the scan area is not a multiple of 8 mm, 1/2/3 /
Scanning is performed by making a plurality of rotations (step S11) as a combination of four rows.

After performing either the scan in step S10 or step S11, the process proceeds to step S12, in which it is determined whether or not to perform display at a pitch of 2 mm.

In the case of performing display at a pitch of 2 mm, an image is reconstructed at a pitch of 2 mm over the entire area of the scanned area, and displayed in a bundle at a position designated by the observer (step S13).

The present invention is not limited to the above-described embodiment, but can be implemented with various modifications. For example, in the first and second embodiments, the basic slice thickness of the detector is 2 mm.
Although described as (fixed), the present invention can be similarly applied to a system in which the number of detector rows is fixed and the basic slice thickness is stepwise variable.

[0026]

According to the X-ray computed tomography apparatus of the present invention described above, it is possible to appropriately obtain an image having a slice thickness which cannot be obtained by one rotation of data acquisition. Further, when scanning is performed with the maximum width permitted by the apparatus depending on the scan area, unnecessary data is not collected, and the amount of exposure to the subject can be reduced.

Even when an image thicker than the basic slice thickness is displayed, more precise observation can be performed by displaying the image at the pitch of the basic slice thickness. Further, an image having a thickness that is a multiple of the basic slice thickness can be reconstructed and displayed.

Further, by displaying the data acquisition conditions specific to the multi-slice CT in association with the displayed image, the image can be uniquely specified, thereby making it easy to compare with another image. In other words, data collection of an image being displayed can be easily reproduced at the time of re-examination, observation of a change with time, or the like.

[Brief description of the drawings]

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

FIG. 2 is a view showing the concept of a multi-slice detector according to the embodiment.

FIG. 3 is a diagram showing a first scanning method using a multi-slice detector.

FIG. 4 is a diagram showing a second scanning method by the multi-slice detector according to the second embodiment of the present invention.

FIG. 5 shows a method of displaying collected data in a system using a multi-slice detector.

FIG. 6 is an example of a flowchart when an inspection is performed by a multi-slice CT apparatus.

FIG. 7 is a view showing a concept of scanning by a single slice detector according to a conventional example of the present invention.

FIG. 8 is a diagram showing a concept of scanning by a multi-slice detector according to a conventional example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... X-ray tube 2 ... X-ray control / high voltage generator 3 ... Radiation detector 4 ... Data acquisition device 5 ... Data storage device 6 ... Image reconstruction device 7 ... Stand / bed 8 ... Stand / bed drive control device 9 ... Operation unit 10 ... Image display unit 11 ... Image processing device 12 ... Image storage device 13 ... CPU

Claims (6)

[Claims] 1. An X-ray computed tomography apparatus for performing a multi-slice scan by a multi-slice detector having a plurality of detector rows each having a basic slice thickness, based on a designated scan area and a required image thickness. An X-ray computed tomography apparatus, comprising: control means for controlling at least one of the basic slice thickness and the number of the detector rows. 2. The apparatus according to claim 1, wherein the control unit controls the basic slice thickness or the number of the detector rows so as to appropriately scan an area equal to the designated scan area. -Ray computed tomography device. 3. If a combination of data obtained by one rotation of the detector row does not provide an image of a required thickness, the combination of the data and data collected by another rotation is used. The X-ray computed tomography apparatus according to claim 1, wherein the image is reconstructed on the basis of the image. 4. When the data collected by each of said detector rows is bundled and used in the body axis direction, a display pitch of an image in the body axis direction is made equal to the basic slice thickness. The X-ray computed tomography apparatus according to claim 1. 5. The X-ray computed tomography apparatus according to claim 4, wherein the bundling of data in the body axis direction is based on a difference between new data. 6. The X-ray computed tomography apparatus according to claim 1, further comprising means for displaying the basic slice thickness and the number of the detector rows in association with a display image.