JPH02185235A - Body movement correcting ct device - Google Patents

Abstract

PURPOSE:To prevent the dislocation of a sliced plane in the middle of scanning by detecting the movement of a subject in the middle of scanning and correcting the sliced plane and a photographing mechanism so as to maintain a positional relation to be always fixed. CONSTITUTION:A bed part 1 is equipped with a top board 4 to support a subject 3 and a height adjusting part 5. A frame part 2 is equipped with the photographing mechanism composed of an X-ray tube 6 to be rotated around a dome 8 and a detector 7, and position sensors 9a, 9b and 9c are provided at different three points. At three different points of the subject, markers 10a, 10b and 10c are provided. By three position sensors, the markers at three points are detected, the three-dimensional position of the subject is detected, and a signal is sent to a three-dimensional position detecting part 11. Here, the three-dimensional position of the subject to be detected and the sliced plane are always compared, and the dislocation quantity is calculated. A bed part control part 13 moves and controls the top board in a body axis direction Z based on the above-mentioned dislocation quantity data, a frame part control part 14 rotates and controls the frame part around an (x) axis and a (y) axis based on the dislocation quantity data in the same way, and the dislocation of the sliced plane is prevented.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention provides a system for correcting a photographing mechanism so that the three-dimensional positional relationship with a subject always remains constant. The present invention relates to a motion corrected CT device.

(Conventional technique)・Pi) For example, in an X-ray CT device, MRIH device, etc., a desired part of the subject is scanned using a camera groove, and based on the original data, a computer performs calculations to create an image. In a CT neck-mounted device for reconstruction, it is essential that the subject do not move during the scan and is maintained in a constant positional relationship with respect to the decoy mechanism.

FIG. 9 shows, as an example, the four components of an X-ray CT apparatus. Broadly speaking, an X-ray CT apparatus is composed of a bed section 1 that supports a subject 3, an X-ray tube 6, and a detector 7. It is composed of a pedestal part 2 that has a built-in.

The bed section 1 includes a top plate 4 that directly supports the subject 3 and is movable in the body axis direction Z, a height adjustment section 5 that adjusts the height position of this Osaka 4 in the vertical direction y, and a pedestal section. 2 is provided with a dome 8 for guiding the subject 3, and the imitation R structure is configured to be rotatable around the dome 8. l indicates an exposure path of the X-ray beam emitted from the X-ray tube 6 toward the detector 7;
The subject 3 is moved in the body axis direction 2 so that the region to be transported (sliced surface) is aligned with the radiation path l.

FIG. 10 shows the subject 3 moved into the dome 8 of the pedestal 2 so that the desired slice plane is aligned with the X-ray radiation path 1. around the
By rotating while performing line radiation, a cut image of the sliced surface is imitated.

When performing scanning with X-rays to imitate a desired slice surface of the subject 3, the subject 3 is
must maintain a constant positional relationship so that its slice plane does not deviate from the X-ray exposure path p. For example, in dynamic scanning, which is normally performed, a contrast agent or tracer is given to the subject and the same slice plane is repeatedly photographed over time.The same pixels of the reconstructed image are analyzed in the time axis direction to determine the circulatory function and blood flow. Tests are being conducted to determine functional parameters such as flow rate, but the slice plane must remain constant without shifting over time.

However, in reality, it is difficult to eliminate the movement of the subject 3. In particular, in a test to determine local cerebral blood flow by performing a dynamic scan with the subject 3 inhaling Xe gas, the subject moves due to the anesthetic effect of the Xe gas, making it impossible to prevent body movement. Therefore, the X-ray absorption data (CT values) obtained over time will vary as shown in FIG. 11, and the analysis results will have low reliability.

For this reason, in the past, the following body motion correction means have been considered in order to prevent such adverse effects.

One of these methods is to forcibly fix the subject to the bed using a fixing device such as a head fixing device. The other method is to use software to correct positional deviations within the slice plane using shadowed data.

(Problems to be Solved by the Invention) However, each of the conventional body motion correction means has the following problems.

First, in the first method, the subject is forcibly fixed to the bed, which not only causes pain to the subject but also imposes a large mental burden on the subject. Next, in the second means, it is possible to correct only the body movement due to two parallel rotations within the slice plane, so complete correction cannot be performed.

The present invention was made in response to the above circumstances.
The object of the present invention is to provide a body motion correction C-"device capable of solving the conventional problems.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a three-dimensional position detecting means for detecting each of the marker functions that indicate the three-dimensional position of a subject, and Accordingly, the slicing surface of the subject is kept constant.J: The apparatus is provided with a control means for controlling at least one of the sea urchin mount section and the bed section.

(Function) A marker function that indicates the three-dimensional position of the subject. For example, by detecting the three-dimensional position of the subject using externally provided marking means or physical characteristic parts of the subject, the coordinate axis can be detected. Locate the top position. At least one of the pedestal section and the bed section is controlled in accordance with this detection result, and the slice plane of the subject is corrected so as to always maintain a constant positional relationship with respect to the copying mechanism. This makes it possible to prevent the slice plane of the object from being warped during scanning.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment in which the body motion correction device of the present invention is applied to an X-ray device, in which numeral 1 indicates a top plate 4 that supports a subject 3 in a bed section. A height adjustment section 5 is provided. Reference numeral 2 is a pedestal section and is equipped with an imaging device consisting of an X-ray tube 6 and a detector 7 that can rotate around a dome 8. Furthermore, a first position sensor 9a, a second position sensor 9b, and a third position sensor 9c are provided at three different locations on the pedestal section 2, and these are the three position sensors provided on the subject 3 as described later. This is for detecting the three-dimensional position of the subject 3 by detecting markers at certain locations. As these position sensors 9a to I9G, for example, sensors using laser light, sensors using ultrasonic waves, etc. are used. As shown in FIG. 2, a first marker 1 is placed at each of three different locations on the subject 3.
0a, a second marker 10b, and a third marker 10G. Materials with small X-ray absorption coefficients are selected for these markers 10a to 10G. Figure 3 shows the body axis direction Z.
This shows the arrangement of the subject in a plane perpendicular to .

Signals detected by the first to third position sensors 9a to 9C are sent to the three-dimensional position detection section 11. This 3
The dimensional position 1 detection unit 11 is composed of a microprocessor, etc., and constantly calculates the three-dimensional position on the coordinates of the subject 3 based on each input detection signal and holds this information. Information on the slice plane of the subject 3 to be layered is input from the input section 12, and this information is added to the three-dimensional position detection section 11. Therefore, referring to this information, the three-dimensional position detecting section 11 constantly compares the detected three-dimensional position of the subject 3 and the slice plane to calculate the amount of deviation.

The bed section control section 13 controls the top plate 4 of the bed section 1 to move a desired amount in the body axis direction Z based on the data regarding the amount of deviation added from the three-dimensional position detection section 11.

The gantry control section 14 controls the gantry section 2 to rotate by a desired amount around the X-axis and around y@, based on the data regarding the displacement added from the three-dimensional position detection section 11. In this way, by adjusting the amount of movement and rotation of the bed section 1 and the pedestal section 2 along the x, y, and z axes, the top plate 4
Even if the upper subject 3 moves and its three-dimensional position changes, the slice plane of the subject 3 always follows the movement and maintains a constant positional relationship with respect to the X-ray exposure path 1 of the imaging mechanism. controlled to maintain

Next, the operation of this embodiment will be explained.

With the slice surface of the subject 3 to be patterned aligned with the X-ray exposure path 1 of the patterning mechanism, X-rays are irradiated by the solid mechanism to start scanning the slice surface. When the subject 3 moves during such a test, the markers 10a to 1 of the 3 cages
Since the position of 0c changes, is this strange or not?
a to 9G, and as a result, the three-dimensional position of the subject 3 is detected by the three-dimensional position detecting section 11. The three-dimensional position detection section 11 further calculates the deviation loss between the slice plane and the three-dimensional position based on the detection result, and sends this data to the bed section control section 13 and the pedestal section control section 1.
Send to 4.

Based on the data on the amount of deviation, the bed section control section 13 and the gantry section control section 14 control the X-ray exposure path p of the foot mechanism on the slice surface.
Control operations are performed to ensure alignment at all times. First, the bed controller 13 performs a control operation to adjust the amount of movement of the top plate 4 in the body axis direction Z. Also, the pedestal section ff, + control section 14
performs a control operation to rotate the pedestal section 2 by a desired amount around the X-axis and the y-axis as shown in FIG.

In this way, the amount of movement of the bed section 1 in two directions and the
, by adjusting the amount of rotation in the y direction, even if the subject 3 moves, the imaging mechanism is controlled so as to follow this movement and always maintain a constant positional relationship with the slice plane. Therefore, the subject 3 is no longer inflicted with pain. Furthermore, since it is possible to correct changes in three-dimensional position, complete correction can be performed. In addition, markers 10a to 1
Instead of 0C, changes in position can be detected by using physical characteristics of the subject 3, such as the ear holes, the tip of the nose, and the eyes, and detecting these with each sensor.

When performing dynamic scanning based on such an embodiment, the slice plane is first recognized and specified during the first scan, which is the base scan, and then the deviation from the base scan is determined from the second scan onwards. is detected and control is performed such that the position is always aligned with the slice plane at that time. As a result, even if the slice plane changes over time, a constant positional relationship between the slice plane and the 1fii shadow ffN side is always maintained, so accurate analysis can be performed.

FIG. 5 shows a second embodiment in which the present invention is applied to an MRI apparatus. First position detection antennas 15a are provided at three different locations on the pedestal section 2, respectively.

A second position detection antenna 15b and a third position detection antenna 15G are provided, and first markers 16 are placed at three different locations on the subject 3 that has moved into the dome 8.
a, a second marker 16b, and a third marker 16G are provided. These markers 16a to 16G are made of non-magnetic material that can be detected by electromagnetic waves, and are attached to the surface of the subject 3 or implanted into the body. An imaging signal antenna 17 is also provided. 18 is a power source for forming a static magnetic field, and 19 is a power source for forming a gradient magnetic field (x, y, z).

The position detection receiver 20 detects the three-dimensional position on the coordinates of the subject 3 based on the phase and width of the signals detected by each of the position detection antennas 15a to 15C, and uses this information to calculate the coordinate axes. Send to container 21. The coordinate axis calculator 21 calculates the three-dimensional position of the subject 3 on the coordinates based on this information, and sends this data to the image reconstruction unit 24. The imaging receiver 22 receives an imaging signal from the imaging signal antenna 17 , and this signal is converted into a digital signal by an A/D converter 23 and then sent to an image reconstruction unit 24 .

The image reconstruction unit 24 reconstructs an image based on the image information. At this time, image reconstruction is performed by aligning the desired slice plane with the three-dimensional position of the subject 3. In other words, when the subject 3 moves during scanning, each time this change is detected and the three-dimensional position is calculated, a control operation is performed to align the slice plane to this three-dimensional position to display the image. Reconfigure. The reconstructed image is displayed on the display section 26 and is also stored on the disk 25.

Next, the operation of this embodiment will be explained.

With the slice plane of the subject 3 to be modeled determined by electrical signals, scanning of the slice plane is started by transmitting and receiving high frequency signals from the imaging signal antenna 17. When the subject 3 moves during such a scan, the positions of the three markers 16a to 16c change, so this change is detected by each antenna 15a to 15G, and as a result, the three-dimensional position of the subject 3 is aligned with the coordinate axis. Arithmetic unit 2
It is calculated by 1. When the subject 3 moves during scanning, the image reconstruction unit 24 detects this change and aligns the slice plane to the three-dimensional position each time the calculated data of the three-dimensional position is input. Control and reconstruct the image.

In this way, in the MRIiES system, each time the three-dimensional position of the subject 3 is detected, the electrical control means performs control to align the slice plane to the three-dimensional position.
Body movement correction when the subject 3 moves can be performed with good followability.

In an MRI device, the scanning time can be the same for both single slices and multi-slices, and the movement of the subject during scanning cannot be ignored, so position control for each slice is insufficient, so position control is performed for every one to several projections. You may also do this. This can be similarly applied to X-ray CT apparatuses that require several seconds or more to scan one slice.

FIG. 6 shows a third embodiment of the present invention, and particularly shows the configuration of a three-dimensional position detection mechanism.

For example, springs 31a to 31d are attached to the cylindrical belt 30 attached to the head of the subject 3 at four locations, and tension sensors 32a to 32d arranged on the inner wall of the dome 8 are provided at the other end of each spring 31a to 31d. It is something. 3
Detection signals from each of the sensors 32a to 32d are input to the dimensional position detection section 33, whereby the three-dimensional position of the subject 3 is calculated, and the amount of deviation from a preset slice plane is calculated. Projection data collection unit 35
In this case, projection data obtained by the following method is collected, and this projection data is sent to the image reconstruction unit 34. The image reconstruction unit 34 performs image reconstruction of the projection data based on the amount of wear data input from the three-dimensional position detection unit 32, and performs control to align the slice plane with the three-dimensional position of the subject 3. Perform operations to reconstruct the image. The reconstructed image is displayed on the display section 3.
6.

In this embodiment as well, since scanning is performed in such a way that the moving reed structure is always aligned with the slice plane according to the movement of the subject, the same effect as described above can be obtained.

In this embodiment, an example in which the three-dimensional position of the subject is detected has been described, but the present invention may be applied to a simple X-ray image or a DSA (digital subtraction angiography) image.

The present invention can be similarly applied to detecting the three-dimensional position of a two-dimensional projected image such as an RI (radio isotope) image. Furthermore, PET (positron emission CT') Vi is installed.

5PCET (single) ton emission C-
) can also be applied to equipment, etc.

Furthermore, the present invention is not only a device for slicing a subject;
As shown in FIG. 7, the present invention can be applied to an apparatus in which a single X-ray is emitted from an X-ray tube 6 to a subject 3 and three-dimensional data is collected by a detector 7 in one scan. Similarly, when performing 3D display such as cross section conversion display or surface display,
As shown in FIG. 8, it can also be applied to a device that performs so-called multi-slicing, in which a series of scans are performed while the subject 3 is moved by the top plate 4, and multi-layered slices are successively visualized. .

[Effect of the Invention 1] As described above, according to the present invention, the movement of the subject during scanning is detected and correction is made so that the slice plane and the imaging mechanism always maintain a constant positional relationship. Misalignment of the slice plane during scanning can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of the body motion complement C1 device of the present invention, FIGS. 2 to 4 are explanatory diagrams of this embodiment, and FIG. 5 is a diagram showing a second embodiment of the present invention. 6 is a block diagram showing a third embodiment of the present invention, FIGS. 7 and 8 are schematic diagrams showing other embodiments of the present invention, and FIGS. 9 and 10 are conventional examples. The side view of FIG. 11 is a characteristic diagram of a conventional example. DESCRIPTION OF SYMBOLS 1... Bed part, 2... Frame part, 3... Subject, 4... Top plate, 8... Dome, 9a-19c... Position sensor,
10a to 10C, 16a to 16G-? -Power, 11.
33... Three-dimensional position detection unit, 13... Bed unit control unit, 14... Frame unit control unit, 15a to 15c... Position detection antenna, 20...
・Receiver for position detection, 24.34...Image book forming section, 31a to 31d...Spring, 32a 7"J to 32d...Tension sensor.

Claims (2)

[Claims] (1) When the subject supported on the bed section is moved to the pedestal section with a built-in imaging mechanism, and the subject moves relative to the imaging mechanism, this movement is followed by a three-dimensional positional relationship with the subject. Body motion correction CT that corrects so that the positional relationship is always constant
In the apparatus, three-dimensional position detection means for detecting each marker function that indicates a three-dimensional position provided on the subject;
A body motion correction CT apparatus comprising: a control means for controlling at least one of a pedestal section and a bed section so as to maintain a constant slice plane of a subject according to a detection result. (2) The body motion correction CT apparatus according to claim 1, wherein the marker function of the subject to indicate the three-dimensional position comprises marking means provided on the subject from the outside.