JP3405760B2 - CT device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is directed to a plurality of light sources (eg X
Source) and a CT having an X-ray detector corresponding to each X-ray source
Regarding the device.

[0002]

2. Description of the Related Art In recent years, as a medical diagnostic apparatus has been developed, a CT apparatus for taking a tomographic image of an arbitrary portion of a subject has come to be widely used. In addition, recently, in order to shorten the imaging of tomographic images, a helical scan that scans the periphery of the subject spirally, calculates the data at each slice position by interpolation processing, and reconstructs a slice image based on this The method is put to practical use.

A conventional helical scan CT apparatus is shown in FIG.
As shown in A, B, and C, one tube 71 continuously rotates around a patient (subject) 70 on a bed 75 that is movable in the body axis direction along a trajectory 76, and a beam 72 The spiral scanning was performed by.

[0004]

However, in the conventional helical scan CT apparatus, since (1) there is only one tube, it is impossible to scan a plurality of points at a certain time. (2) Only one scanning condition can be scanned at a time. (3) When the heat capacity of the optical system is full, it is necessary to wait until it cools down. Also, it takes time to replace the optical system when a failure occurs. (4) It is necessary to scan in a short time before the contrast agent has left, but it is not possible to scan in a short time because there is only one tube. (5) Since there is only one tube, it is not possible to scan a wide range in a fixed time. There was an inconvenience.

The present invention has been made in view of the above inconvenience, and an object thereof is to provide a CT apparatus which solves the problem caused by one tube.

[0006]

To achieve the above object, the present invention provides an X-ray CT apparatus for reconstructing a CT image of a subject based on projection data obtained by scanning the subject. A first imaging system having a first X-ray source for irradiating X-rays and a first detector for detecting X-rays transmitted through the subject, and a second X-ray for irradiating X-rays A second imaging system having a source and a second detector for detecting X-rays transmitted through the subject, a bed in which the subject is movable in the body axis direction, and the first imaging system Shooting conditions,
Setting means capable of setting an imaging condition relating to the second imaging system, a distance between the first imaging system and the second imaging system in the body axis direction, and a moving speed of the subject, and the setting means. Based on the imaging conditions for the first imaging system, the imaging conditions for the second imaging system, the interval in the body axis direction, and the moving speed of the subject set by It is characterized by comprising a photographing system and a control means for controlling the bed.

[0007]

[0008]

According to the present invention, the photographing conditions of the first photographing system and the second photographing system, the distance between the first photographing system and the second photographing system in the body axis direction, and the movement of the subject. The speed is set, and the subject is scanned according to the set conditions. Accordingly, for example, if the first imaging system and the second imaging system are made to follow the same orbit and are scanned, it is possible to see the temporal change of the image at a plurality of slice positions.
It is possible to effectively use a plurality of photographing systems, such as a dual energy image can be obtained by irradiating different X-ray energies from the radiation source and the second X-ray source.

[0009]

[0010]

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of an X-ray CT apparatus according to the present invention.

The X-ray CT apparatus shown in the drawing has three tubes (X-ray tubes) 3-1, 3-2, 3-3 which can rotate independently or in conjunction with each other at intervals parallel to each other, and each of them. Three sets of detectors 4-1, 4-2, 4-provided corresponding to the tube
3 and 3 sets of data collecting sections 5-1, 5-2, 5-3 for collecting and projecting the respective projection data detected by the respective detectors, and the tubes 3-1 and 3 −
2, 3-3 and the rotation control unit 7 for controlling the rotation of the detectors 4-1, 4-2, 4-3 and the tubes 3-1, 3-2, 3-3.
The optical system position control unit 8 for controlling the distance between the two is included.

The X-ray CT apparatus further includes tubes 3-1 and 3-.
X-ray control unit 6 for controlling the X-ray dose of 2, 3-3
A bed driving unit 10 for driving the bed 11, a controller 9 for controlling the bed driving unit 10, and a central control unit (CP).
U) 12, a monitor 13 connected to the central control unit 6 via a bus (not shown), a keyboard 14 as a scanning condition input device, an internal memory 15, and a magnetic disk 16 for storing collected data and image data. is doing.

The central control unit 12 controls the X-ray control unit 6, the rotation control unit 7, the optical system position control unit 8, the controller 9 and the image reconstruction device (not shown), and the X-ray C of this embodiment is used.
It controls the operation of the entire T device. In addition, the X-ray controller 6
Under the control of the central control unit 12, X for each X-ray tube (tube) is
Control the line. Then, an X-ray tube (for example, tube 3
-1 is exposed to X-rays and other X-ray tubes (for example, tube 3-
The X-ray dose of 2) can be set to different amounts.

The rotation control unit 7 controls the rotation of each X-ray tube and / or detector under the control of the central control unit 12, and the set of the X-ray tube and the detector is controlled by the rotation control unit 7 to another X-ray tube. It is capable of rotating independently of the set of tube and detector. The optical system position control unit 8 controls the movement of each X-ray tube and the detector in the bed direction (the body axis direction of the patient (subject)) under the control of the central control unit 12.
Specifically, an X-ray tube (tube) is set at the scanning start position, and which of the X-ray tubes 3-1, 3-2, and 3-3 is in the bed direction (positive direction or negative direction). Control how much and at what speed to move. The controller 9 drives the bed driving unit 10 under the control of the central control unit 12 to move the bed 1 in the body axis direction of the patient.

FIG. 2 is a block diagram showing the configuration of each control unit shown in FIG. 1. The central control unit 12 refers to the scanning condition list 17 shown in FIG. A command (signal) is sent to the line control unit 6, the rotation control unit 7, the optical system position control unit 8, and the controller 9 to control the respective control units 6, 7, 8, 9 and at the same time, the respective control units 6, 7, 8 and 9 and information from the detectors 4-1, 4-2 and 4-3 (for example, rotation angle, position of optical system (interval), position of bed, etc. and X-ray transmission amount from each detector). Etc.) to feedback control each control unit 6, 7, 8, 9. Based on the feedback control, each of the control units 6, 7, 8 and 9 controls the X-ray generation amount of each X-ray source, the rotation and movement of the tube and the detector, and the movement control of the bed. Rotation and movement of the tube and the detector have a rotation driving device (not shown) and a moving device (not shown) for each set of detectors corresponding to the respective tubes, and the rotation control 7 and the optical system are provided. It is driven independently or in conjunction with each other based on the drive signal from the controller 8.

The scanning condition list 17 is usually the magnetic disk 1.
6 and is read from the magnetic disk 16 to the internal memory 15 and referred to by the central control unit 12 when the X-ray CT apparatus 1 is activated, the operator changes the conditions of the scanning condition list 17 from the keyboard 14. You can add, register, and delete. In this case, the scanning condition list 17 is displayed on the monitor 13 as shown in FIG. 2, so that the operator can easily input the scanning conditions.
The scanning condition list 17 stores scanning conditions for each tube, and a unique number is assigned to each tube in advance, and this number cannot be changed. Reference numeral 17 in FIG. 2 shows an example of the scanning condition list, and in the first line, the state graph of the first tube 3-1 (for example, this tube is used ... 1; not used ... 2 A value indicating the state of the tube such as failure ... 3), X-ray conditions (X-ray voltage and current), rotation amount (angle) of the tube and detector, movement amount of the tube and detector, etc. The condition (information) is stored and the second tube 3-2 is in the second line.
Of the third tube 3-3 in the third row, and the nth tube 3-n in the nth row, the X-ray conditions (X-ray voltage and current), the tube and Conditions (information) such as the rotational speed of the detector, the moving amount of the tube and the detector, etc. are stored. As an example of the driving operation of the X-ray generation source, the tube, and the detector based on the scanning condition list, for example, the central control unit scans the first tube 3-1 from the scanning condition list in the scanning condition “state = 1; 120 KV; 5”.
0 mA; 1 rps; 2 mmps "is read and a command (signal) based on the scanning condition is sent to each of the control units 6, 7, and 8, the X-ray control unit 6 supplies the X-ray generation source of the tube 3-1. The X-ray generation amount is controlled by setting the voltage to 120 KV and the current to 50 mA, and the rotation control unit 7 controls the tube 3-1 and the detector 4.
-1 sends a drive control signal to the rotation driving device of the tube 3-1 and the detector 4-1 so that the rotation speed of -1 becomes 1 rps, and the optical system position control unit 8 causes the tube 3-1 and the detector 4-1. Tube 3-1 and detector 4-1 so that the movement amount of
A drive control signal to the moving device (not shown).

In the present embodiment, the X-ray CT apparatus 1 performs a spiral scan on the subject, and a data reconstruction device (not shown) uses the spiral scan to detect the detector 4-.
A set of data obtained by 1, 4-2, and 4-3 and position data of the bed 10 in the body axis direction are fetched, and an arbitrary slice is obtained based on the fetched data (see Japanese Patent Laid-Open No. 2-111129). A set of position interpolation data is obtained, and image reconstruction is performed based on this set of interpolation data.

In the present embodiment, if an error occurs during the scanning of the tube, for example, X of the first tube (tube 3-1).
If an error occurs in the line portion, the X-ray controller 6 determines from the status bit that an error has occurred in the tube 3-1 and sends a status (status) bit to the central controller 12. The status bit consists of a unique number of the tube and a bit flag indicating the status of the tube. The central control unit 12 checks the status bit and sends the use prohibition code of the tube 3-1 to the rotation control unit 7 and the optical system position control unit 8. Rotation control unit 7
The optical system position controller 8 sends a drive stop signal to the rotary drive device and the moving device for the tube 3-1 and the detector 4-1. After confirming that all the movements of the tube 3-1 have stopped, the central control unit 12 sends the scanning conditions and the like of the first tube 3-1 to other tubes not currently used, and Tube 3-1
Use instead of.

The effects of this embodiment will be described below.

(B) A helical dynamic scan can be performed.

The helical scan is a method of spirally scanning an object, and can swiftly scan a wide range. Also,
An image can be formed in any part of the scanned range. On the other hand, in the dynamic scan, it is possible to observe and photograph a temporal change of the scanning position by continuously scanning a certain position. Then, according to the CT apparatus of the present embodiment, FIG.
As shown in (A), a plurality of (three in the figure) tubes 31a to
By using 31c, when the range d is helically scanned, it is possible to see the change with time of the image at each of the positions P _{1 to} P _{4 as shown} in FIG. That is, helical dynamic scan is possible.

Further, when a difference image is created using helical dynamic scanning and the temporal change of the contrast agent is observed, it is necessary to make the orbits of the respective tubes 31a to 31c equal to each other as shown in FIG. About this, tube 31a-
It can be easily set from the relationship between the interval of 31c and the feeding speed of the subject. Further, in order to decide how many seconds after the same region of the subject is scanned, it can be decided by the interval between the tubes 31a to 31c and the attachment angle of the tubes 31a to 31c. Further, by shifting the attachment angles of the tubes 31a to 31c, the interval h between the tubes 31a to 31c can be made narrower than the width of the tubes themselves as shown in FIG. That is, for example, when the radius of the tube is 100 [mm], the interval between the tubes is at least 20 unless the mounting angle is set.
Although 0 [mm] is required, this interval can be set to 0 [mm] or more by attaching a mounting angle.

If such a helical dynamic scan is used, a cine display 34 can be obtained along a temporal change in a three-dimensional image as shown in FIG. 3 (c). This display is expected to be effectively used in the field of brain surgery, for example.

(B) It is possible to scan the same range at substantially the same time under a plurality of photographing conditions.

For example, if the subject (patient) 40 is simultaneously scanned from above and from the side by two sets of optical systems 41 and 42 as shown in FIG. Bottom-top image and right-left
You can get a scanogram of the image. In addition, scanning in which the rotation speed of the beam or the optical system is changed for each optical system can be performed almost simultaneously in the same range. Thus, it is possible to perform scanning under different scanning conditions before the contrast agent is washed away. Further, the patient throughput is improved and the burden on the patient is reduced. Then, it is possible to save the trouble of rescanning when changing the conditions and performing scanning or when photographing fails. This is particularly effective in research that requires scanning under various conditions.

(C) At the same time, a plurality of parts can be photographed under the scanning conditions according to the parts.

At the same time, a plurality of parts can be scanned under the scanning conditions according to the parts. This is, for example, in the case of group screening
More effective. In this case, for example, in FIG.
The tube 51 can scan the chest and the tube 52 can scan the abdomen. These scans can be performed at the same time, and the scan conditions can be set according to the site, so accurate diagnosis can be performed, X-ray exposure can be minimized, and the scan time per person is short. I'm done.

(D) It is possible to switch to another tube even when the currently used tube becomes unusable.

A major cause of downtime in conventional devices is a tube failure. However, in this embodiment, since there are a plurality of tubes, a tube that is not used when the capacity of the tube is full or the tube has a failure can be used as a spare. Therefore, although it is impossible to perform an inspection that requires the use of all the tubes at the same time, the inspection can be continued using the remaining tubes. Therefore, there is no downtime due to the failure of the tube, and it is possible to always deal with an emergency inspection.

(E) A certain range can be scanned in a shorter time than before.

FIG. 8A shows a conventional helical scan in which spiral scanning is performed with one tube, and one scanning time in this case is defined as t. On the other hand, FIG. 8B shows a case where the same region is scanned by two tubes according to the present invention, and one scanning time in this case is 1/2 t. As described above, according to the present invention, when scanning is performed with n optical systems, it is possible to take an image in 1 / n of the conventional time. This is more effective when scanning must be performed within a short time such as when a contrast agent is injected.

(F) The spatial resolution can be improved.

When the same range is photographed within a certain period of time, the plurality of optical systems are photographed, so that the scanning can be made dense and the spatial resolution in the direction along the body axis can be improved.

(G) Dual energy scan can be performed.

By using different X-ray energies in two or more tubes, a dual energy scan can be easily performed.

That is, by photographing the same region with two or more kinds of X-ray energies, an image for each energy can be obtained. Using these images, it is possible to obtain an image representing the electron distribution density, the degree of Compton scattering, and the photoelectric effect by calculation. These are useful information for estimating the elemental composition of the subject. Since the ratio of the Compton scattering intensity to the photoelectric effect intensity differs for each element, the X-ray absorption is determined by these two scattering effects and the substance density.

The present embodiment is not limited to the above embodiment. For example, as shown in FIG. 10A, a plurality (three in the figure) of gantry 65 to 67 are arranged in parallel to perform scanning. May be. With such a configuration, the interval between the X-ray tubes cannot be narrowed to a certain extent or less, but FIG.
As shown in (B), each gantry 65-67 can be tilted.

[0039]

As described above, according to the present invention,
The inspection efficiency can be greatly improved by the one-tube CT device.

Further, it is possible to scan the fixed range in a shorter time than the conventional one, and it is possible to obtain the effect that the dual energy scan becomes possible.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an X-ray CT apparatus which is an embodiment of a CT apparatus according to the present invention.

FIG. 2 shows an example of a block diagram of a control unit and a scanning condition list in the embodiment of FIG.

FIG. 3 is a partial view A showing an example of a helical dynamic scan, a partial view B shows a plurality of head images taken over time by the helical dynamic scan, and a partial view C is a three-dimensional image obtained by the helical dynamic scan. An example of a cine display along with a change over time will be shown.

FIG. 4 shows an example in which a tube is aligned with a spiral orbit of a helical scan.

FIG. 5 shows an example in which the mounting angle of each tube is shifted.

FIG. 6 is a partial view A showing an example of scanning the same range at substantially the same time under a plurality of imaging conditions, and a partial view B shows a resulting image.

FIG. 7 shows an example in which another site is simultaneously scanned under scanning conditions according to the site.

FIG. 8 is a partial view A showing a conventional helical scan in which a single tube performs a spiral scan, and a partial view B shows a case where two tubes according to the present invention scan the same region.

FIG. 9 is a perspective view showing an example of scanning by a conventional helical scan CT apparatus, a partial view B is a side view, and a partial view C is a view seen from a gantry.

FIG. 10 shows an example of shooting using a plurality of gantry.

[Explanation of symbols]

1 X-ray CT system (CT system) 2 mounts 3-1, 3-2, 3-3 tube 4-1, 4-2, 4-3 detector 11 sleeper 10 Sleeper drive 12 Control unit

─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-3-70547 (JP, A) JP-A-4-22343 (JP, A) JP-A-4-54942 (JP, A) JP-A-53- 42696 (JP, A) JP 54-92192 (JP, A) JP 55-122536 (JP, A) JP 59-111738 (JP, A) JP 62-167538 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) A61B 6/00-6/14

Claims (5)

(57) [Claims] 1. An X-ray CT apparatus for reconstructing a CT image of the subject based on projection data obtained by scanning the subject, a first X-ray source for irradiating X-rays, and the subject. A first imaging system having a first detector for detecting X-rays transmitted through, a second X-ray source for exposing X-rays, and for detecting X-rays transmitted through the subject. A second imaging system having a second detector, a bed in which the subject is movable in the body axis direction, imaging conditions related to the first imaging system, imaging conditions related to the second imaging system, and Setting means capable of setting the distance between the first imaging system and the second imaging system in the body axis direction and the moving speed of the subject, and imaging relating to the first imaging system set by the setting means Conditions, imaging conditions regarding the second imaging system, intervals in the body axis direction, the test Of based on the moving speed, the first imaging system, X-rays CT apparatus characterized by comprising a control means for controlling said second imaging system and the bed. 2. A storage unit for storing shooting conditions, wherein the setting unit reads out the shooting conditions stored in the storage unit and relates to the shooting conditions for the first shooting system and the second shooting system. The X-ray CT apparatus according to claim 1, further comprising display means for displaying imaging conditions. 3. The X-ray condition of the first X-ray source and the second X-ray condition
The X-ray CT apparatus according to claim 1 or 2, wherein the X-ray condition of the X-ray source is set. 4. The X according to claim 1, wherein the setting unit sets whether or not to use the first photographing system and the second photographing system. Line C
T device. 5. The control means controls the first imaging system, the second imaging system and the bed so as to perform a helical scan on the subject. X-ray C according to any one of claims 1 to 4.
T device.