JP2004000605A - X-ray ct device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray CT device having much improved examination efficiency compared to a one bulb type X-ray CT device. <P>SOLUTION: This X-ray CT device comprises a first photography system having a first X-ray tube 3-1 for irradiating an X-ray and a first detector 4-1 for detecting the X-ray transmitted through a subject, a second photography system having a second X-ray tube 3-2 for irradiating an X-ray and a second detector 4-2 for detecting the X-ray transmitted through the subject, and a central control unit 12. When the first photography system generates an error during scanning, the central control unit makes the second photography system scan under a photography condition of the first photography system. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an X-ray CT apparatus having a plurality of light sources (for example, X-ray sources) and an X-ray detector corresponding to each X-ray source.
[0002]
[Prior art]
In recent years, as the development of medical diagnostic apparatuses has been advanced, CT apparatuses for capturing a tomographic image of an arbitrary portion of a subject have been increasingly used. In recent years, in order to shorten the tomographic imaging, a helical scan that scans around the subject in a spiral shape, calculates data at each slice position by interpolation processing, and reconstructs a slice image based on the calculated data. The method is put into practical use.
[0003]
As shown in FIGS. 9A, 9B, and 9C, the conventional helical scan CT apparatus has a configuration in which one tube 71 moves along a trajectory 76 around a patient (subject) 70 on a bed 75 that can move in the body axis direction. The beam 72 continuously rotates, and the beam 72 performs a spiral scan.
[0004]
[Problems to be solved by the invention]
However, the conventional helical scan CT apparatus includes:
(1) Since there is only one bulb, it is not possible to scan a plurality of locations 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 leaves, but it is not possible to scan in a short time because there is only one tube.
(5) Since there is only one bulb, it is not possible to scan a wide range in a fixed time.
There was an inconvenience.
[0005]
The present invention has been made in view of the above-described inconveniences, and has as its object to significantly improve the examination efficiency compared to a single-tube X-ray CT apparatus.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an X-ray CT apparatus for reconstructing a CT image of the subject based on projection data obtained by scanning the subject. A first imaging system having a radiation source and a first detector for detecting X-rays transmitted through the subject; a second X-ray source for exposing X-rays and X-rays transmitted through the subject; A second imaging system having a second detector for detecting a line, and if the first imaging system has an error during scanning, the second imaging system is replaced by the first imaging system. And a control unit for performing scanning under photographing conditions.
[0007]
The control unit may prohibit use of the first imaging system when an error occurs during scanning of the first imaging system.
[0008]
Further, it is preferable that the second imaging system is not used during scanning of the first imaging system.
[0009]
According to another aspect of the present invention, there is provided an X-ray CT apparatus configured to reconstruct a CT image of the subject based on projection data obtained by scanning the subject. A first imaging system having an X-ray source and a first detector for detecting X-rays transmitted through the subject, and a second X-ray source for exposing X-rays and transmitting the X-rays through the subject A second imaging system having a second detector for detecting the detected X-rays, the energy of X-rays emitted from a first X-ray tube of the first imaging system, and the second imaging system And control means for scanning the same position of the subject by making the energy of X-rays emitted from the second X-ray tube different from each other.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of the X-ray CT apparatus according to the present invention.
[0011]
The X-ray CT apparatus shown in the drawings includes three tubes (X-ray tubes) 3-1, 3-2, and 3-3 that can rotate independently or in conjunction with each other at parallel intervals, and each of the tubes has Corresponding three sets of detectors 4-1, 4-2, 4-3 and three sets of data for collecting and projecting respective projection data detected by the respective detectors for easy processing. A rotation control unit that controls the rotation of the collection units 5-1, 5-2, and 5-3, the tubes 3-1, 3-2, and 3-3, and the detectors 4-1, 4-2, and 4-3. 7 and an optical system position control unit 8 for controlling the distance between the bulbs 3-1, 3-2, and 3-3.
[0012]
The X-ray CT apparatus further includes an X-ray control unit 6 that controls the amount of X-rays emitted from the tubes 3-1, 3-2, and 3-3, a bed driving unit 10 that drives the bed 11, and a bed driving unit 10 , A central control unit (CPU) 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, collected data And a magnetic disk 16 for storing image data.
[0013]
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 an image reconstruction device (not shown), and controls the entire X-ray CT device of the present embodiment. Controls the operation. The X-ray control unit 6 controls X-rays for each X-ray tube (tube) under the control of the central control unit 12. Then, the X-ray dose irradiated by a certain X-ray tube (for example, the tube 3-1) and the X-ray dose irradiated by another X-ray tube (for example, the tube 3-2) are set to different amounts. it can.
[0014]
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 X-ray tubes and detectors is controlled by the rotation control unit 7 to control other X-ray tubes and / or detectors. It can rotate independently of the set of detectors. The optical system position control unit 8 controls the movement of each X-ray tube and the detector in the direction of the bed (in the direction of the body axis 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 any one of the X-ray tubes 3-1, 3-2, and 3-3 is set in the bed direction (positive direction or negative direction). In the direction) and at what speed. The controller 9 drives the couch driving unit 10 under the control of the central control unit 12 to move the couch 1 in the body axis direction of the patient.
[0015]
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. 6. A command (signal) is sent to the rotation control unit 7, the optical system position control unit 8, and the controller 9 to control the control units 6, 7, 8, and 9, and to control the control units 6, 7, 8, and 8. , 9 and the detectors 4-1 4-2, and 4-3 (for example, the rotation angle, the position (interval) of the optical system, the position of the bed, and the amount of X-ray transmission from each detector). Input and feedback control the respective control units 6, 7, 8, and 9. Each of the control units 6, 7, 8, 9 controls the amount of X-rays generated by each X-ray source, rotation and movement of the tube and detector, and movement of the bed based on the feedback control. The rotation and movement of the tube and the detector have a rotation driving device (not shown) and a movement device (not shown) for each set of the detector corresponding to each tube, and a rotation control 7 and an optical system. They are driven independently or in conjunction with each other based on a drive signal from the control unit 8.
[0016]
The scanning condition list 17 is normally stored on the magnetic disk 16, and is read from the magnetic disk 16 into the internal memory 15 when the X-ray CT apparatus 1 is started and referred to by the central control unit 12. 17 conditions can be changed, added, registered, and deleted from the keyboard 14. 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 the tube in advance, and this number cannot be changed. Reference numeral 17 in FIG. 2 indicates an example of the scanning condition list, and the first line shows a state graph of the first bulb 3-1 (for example, use this bulb 1; not use 2) A value indicating the state of the tube such as failure 3), X-ray conditions (X-ray voltage and current), the amount of rotation (angle) of the tube and the detector, and the amount of movement of the tube and the detector. The conditions (information) are stored, the second row is the second bulb 3-2, the third row is the third bulb 3-3, and the nth row is the nth bulb 3 -N state flag, X-ray conditions (X-ray voltage and current), rotation speed of the tube and the detector, and conditions (information) such as the moving amount of the tube and the detector are stored. As an example of the driving operation of the X-ray source, the tube, and the detector according to the scanning condition list, for example, the central control unit scans the first tube 3-1 from the scanning condition list with the scanning condition “state = 1; 120 KV; 50 mA; 1 rps; 2 mmps ", and sends a command (signal) based on the scanning condition to each of the control units 6, 7, and 8. When the X-ray control unit 6 supplies a voltage to the X-ray generation source of the tube 3-1, The X-ray generation amount is controlled with 120 KV and a current of 50 mA, and the rotation control unit 7 controls the tube 3-1 and the detector 4-1 so that the rotation speed of the tube 3-1 and the detector 4-1 is 1 rps. The optical system position control unit 8 sends a drive control signal to the rotation driving device, and the optical system position control unit 8 moves the tube 3-1 and the detector 4-1 so that the amount of movement of the tube 3-1 and the detector 4-1 is 2 mmps. A drive control signal is sent to a device (not shown).
[0017]
In the present embodiment, the X-ray CT apparatus 1 performs a helical scan on the subject, and the data reconstructing apparatus (not shown) uses the helical scan to detect the detectors 4-1 and 4-2. A set of data obtained in step 4-3 and position data of the bed 10 in the body axis direction are fetched, and interpolation data set at an arbitrary slice position is obtained based on the fetched data by an interpolation process (see Japanese Patent Application Laid-Open No. 2-211129). And image reconstruction is performed based on the set of interpolation data.
[0018]
In the present embodiment, if an error occurs during the scanning of the tube, for example, if an error occurs in the X-ray portion of the first tube (tube 3-1), the error occurs in the tube 3-1. The X-ray controller 6 discriminates the occurrence from the status bits, and sends a status (status) bit to the central controller 12. The status bit comprises a unique number of the bulb and a bit flag indicating the state of the bulb. The central control unit 12 checks the status bit, and sends a use prohibition code of the bulb 3-1 to the rotation control unit 7 and the optical system position control unit 8. The rotation control unit 7 and the optical system position control unit 8 send a drive stop signal to the rotation driving device and moving device of 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 of the first tube 3-1 to other tubes which are not currently used, and sends the same. A tube is used in place of the tube 3-1.
[0019]
Hereinafter, effects of the present embodiment will be described.
[0020]
(B) Helical dynamic scan can be performed.
[0021]
Helical scan is a method in which a subject is spirally scanned, and can scan a wide range quickly. Also, any part of the scanned range can be converted into an image. On the other hand, in the dynamic scan, it is possible to observe and photograph a temporal change in the scanning position by continuously scanning a certain position. Then, according to the CT apparatus of the present embodiment, as shown in FIG. 3A, when the range d is helically scanned by a plurality of (three in the figure) tubes 31a to 31c as shown in FIG. In FIG. 7, the temporal change of the image at each of the positions P1 to P4 can be seen. That is, helical dynamic scanning becomes possible.
[0022]
Also, when a difference image is created using helical dynamic scanning and the change over time of the contrast agent is observed, it is necessary to make the trajectories of the respective bulbs 31a to 31c equal as shown in FIG. This can be easily set from the relationship between the interval between the tubes 31a to 31c and the feeding speed of the subject. The number of seconds after which the same part of the subject is scanned can be determined by the intervals between the tubes 31a to 31c and the mounting angles of the tubes 31a to 31c. Further, by shifting the mounting angles of the tubes 31a to 31c, the interval h between the tubes 31a to 31c can be made smaller than the width of the tube itself, as shown in FIG. That is, for example, when the radius of the tube is 100 [mm], the interval between the tubes needs to be at least 200 [mm] unless the mounting angle is set, but when the mounting angle is set, this interval is reduced to 0 [mm]. ] Or more.
[0023]
Then, by using such a helical dynamic scan, a cine display 34 along a temporal change can be made in a three-dimensional image as shown in FIG. This display is expected to be effectively used, for example, in the field of brain surgery.
[0024]
(B) The same range can be scanned at almost the same time under a plurality of shooting conditions.
[0025]
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. 6A, a top-bottom (top) as shown in FIG. A scanogram of a (bottom) image and a right-left image can be obtained. Scanning in which the beam and the rotation speed of the optical system are changed for each optical system can be performed almost simultaneously in the same range. Thus, scanning can be performed 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, when scanning is to be performed under different conditions or when photographing has failed, the trouble of rescanning can be saved. This is particularly effective in research or the like that requires scanning under various conditions.
[0026]
(C) A plurality of parts can be photographed at the same time under scanning conditions corresponding to the parts.
[0027]
At the same time, a plurality of parts can be scanned under scanning conditions corresponding to the parts. This is more effective, for example, in the case of mass screening. In this case, for example, in FIG. 7, 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 scanning conditions can be set to the conditions corresponding to the respective parts, so that accurate diagnosis can be made, X-ray exposure can be minimized, and the scanning time per person is short. I'm done.
[0028]
(D) Even when the tube in use becomes unusable, it can be switched to another tube.
[0029]
A major cause of downtime in conventional devices is tube failure. However, in this embodiment, since there are a plurality of bulbs, unused bulbs can be used as spares when the capacity of the bulbs is full or when the bulbs are out of order. For this reason, although it is not possible to perform an inspection that requires all the bulbs to be used at the same time, the inspection can be continued using the remaining bulbs. Therefore, there is no downtime due to the failure of the tube, and it is possible to always respond to an urgent inspection.
[0030]
(E) A certain range can be scanned in a shorter time than before.
[0031]
FIG. 8A shows a conventional helical scan in which helical scanning is performed with one tube, and one scanning time in this case is t. On the other hand, FIG. 8 (B) shows a case where the same part is scanned by two bulbs according to the present invention. In this case, one scanning time is 1 / 2t. As described above, when scanning is performed by the n optical systems according to the present invention, it is possible to capture 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.
[0032]
(F) Spatial resolution can be improved.
[0033]
When the same range is photographed within a certain period of time, the photographing is performed by a plurality of optical systems, so that the scanning can be performed densely and the spatial resolution in the direction along the body axis can be improved.
[0034]
(G) Dual energy scan can be performed.
[0035]
If different X-ray energies are used in two or more bulbs, dual energy scanning can be easily performed.
[0036]
That is, by photographing the same site with two or more types of X-ray energies, an image for each energy can be obtained. Using these images, images representing the electron distribution density, the degree of Compton scattering, and the photoelectric effect can be obtained by calculation. These are useful information for estimating the element composition of the subject. Since the ratio of the intensity of the Compton scattering to the intensity of the photoelectric effect differs for each element, the X-ray absorption is determined by the two scattering effects and the density of the substance.
[0037]
Note that the present embodiment is not limited to the above-described embodiment. For example, as shown in FIG. 10A, a plurality of (three in the figure) gantry 65 to 67 may be arranged for scanning. . In such a configuration, the distance between the X-ray tubes cannot be reduced to a certain level or less, but the gantry 65 to 67 can be tilted as shown in FIG.
[0038]
【The invention's effect】
As described above, the inspection efficiency can be greatly improved compared to a single-tube CT apparatus. Further, if an error occurs during scanning of the first imaging system, by controlling the second imaging system to scan under the imaging conditions of the first imaging system, downtime due to a failure of the tube can be reduced. Can be.
[Brief description of the 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 a configuration diagram of a control unit and an example of a scanning condition list in the embodiment of FIG.
FIG. 3 shows an example of a helical dynamic scan, FIG. 3B shows a plurality of head images taken over time by the helical dynamic scan, and FIG. 3C shows a three-dimensional image of the helical dynamic scan. An example of a cine display along with a change over time is shown.
FIG. 4 shows an example in which a tube is adjusted to a helical trajectory 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 showing an example in which the same range is scanned at substantially the same time under a plurality of photographing conditions, and a partial view B shows a resulting image.
FIG. 7 shows an example in which another part is simultaneously scanned under scanning conditions corresponding to the part.
FIG. 8A shows a conventional helical scan in which a helical scan is performed with one tube, and FIG. 8B shows a case where the same region is scanned with two tubes according to the present invention.
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 imaging using a plurality of gantry.
[Explanation of symbols]
1 X-ray CT equipment (CT equipment)
2 Mounts 3-1, 3-2, 3-3 Tubes 4-1, 4-2, 4-3 Detector 11 Bed 10 Bed drive unit 12 Control unit

Claims (4)

An X-ray CT apparatus for reconstructing a CT image of the subject based on projection data obtained by scanning the subject,
A first imaging system having a first X-ray source for emitting X-rays and a first detector for detecting X-rays transmitted through the subject;
A second imaging system having a second X-ray source for emitting X-rays and a second detector for detecting X-rays transmitted through the subject;
An X-ray CT apparatus, comprising: a control unit for causing the second imaging system to scan under the imaging conditions of the first imaging system when an error occurs during scanning of the first imaging system. . 2. The X-ray CT apparatus according to claim 1, wherein the control unit prohibits use of the first imaging system when an error occurs during scanning of the first imaging system. The X-ray CT apparatus according to claim 1, wherein the second imaging system is not used during a scan of the first imaging system. An X-ray CT apparatus for reconstructing a CT image of the subject based on projection data obtained by scanning the subject,
A first imaging system having a first X-ray source for emitting X-rays and a first detector for detecting X-rays transmitted through the subject;
A second imaging system having a second X-ray source for emitting X-rays and a second detector for detecting X-rays transmitted through the subject;
The energy of X-rays emitted from a first X-ray tube of the first imaging system and the energy of X-rays emitted from a second X-ray tube of the second imaging system are made different from each other, An X-ray CT apparatus comprising: control means for scanning the same position of a subject.

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