JP2847517B2 - Combined tomographic imaging system - Google Patents

Description

The present invention relates to an NMR imaging apparatus for obtaining a tomographic image of a subject using nuclear magnetic resonance (hereinafter abbreviated as NMR), and a cross section of the subject. And an X-ray computed tomography apparatus for obtaining a distribution image of the X-ray absorption coefficient. 2. Description of the Related Art Among apparatuses for obtaining a tomographic image of a subject, an X-ray computer tomography apparatus (hereinafter abbreviated as X-ray CT) is for imaging a difference in an X-ray absorption coefficient of each tissue of the subject. The NMR imaging apparatus is characterized by being able to image differences in the density of hydrogen nuclei and differences in relaxation times. As described above, the diagnostic information obtained by the two imaging devices is different, and in order to increase the accuracy of diagnosis, it is not rare to use two inspection methods in combination. In this case, a hospital requires space for two rooms, a CT room and an NMR imaging room, and also requires two sets of image processing units having similar calculation capabilities.
Also, the patient needs to move between the two rooms. In order to display two types of images on the same display, it is necessary to move data using a storage medium such as a magnetic tape, and the operation of aligning the slice positions of both images is also troublesome. [Problems to be Solved by the Invention] As described above, when the conventional apparatus is used, the hospital needs to communicate with the CT room.
A space for two NMR imaging rooms must be prepared, and one signal processing unit having a similar calculation capability is required for each, a total of two sets. Normally, it takes a long time to acquire images by NMR imaging, and the signal processing unit does not always use its computing capacity at all times. From these two points, the conventional apparatus has a great waste. Further, as a clinically important problem, when performing diagnosis by comparing X-ray CT images and NMR imaging images, it is difficult to match the slice positions of both images within a few mm error, and the images are stored separately. Since the data is recorded on the medium, the display on the same display is made by moving the data via a magnetic tape or floppy disk. SUMMARY OF THE INVENTION An object of the present invention is to provide a composite tomographic imaging apparatus capable of easily performing composite image diagnosis of X-ray CT / NMR imaging at low cost and with a small burden on a patient. [Means for Solving the Problems] The cost reduction of the apparatus can be achieved by sharing the signal processing system and the console, which are provided separately for the X-ray CT and the NMR imaging. In addition, patient burden reduction and X-ray CT
Correlation between slice positions in NMR imaging can be achieved by providing a scanner part for X-ray CT and a gantry part of the NMR imaging apparatus in the same examination room and sharing the bed. However, most of the static magnetic field generating means of the NMR imaging apparatus generate a strong magnetic field of 0.1 to 1.5 Tesla, so if a magnetic substance is present near the apparatus, it is dangerous and deteriorates the performance of the apparatus. Will be. Therefore, the problem is solved by providing a magnetic shield around or around the NMR imaging apparatus. [Operation] The NMR imaging unit is provided with a magnetic shielding agent on or around the housing, so that performance deterioration and malfunction of both imaging units do not occur. The couch has the stroke required to insert the subject into both gantry,
The slice position in both imaging units can be adjusted by the control of the CPU. In addition, imaging processors and sequences are responsible for image acquisition processing,
During the image acquisition period of imaging, post-processing of already acquired images using the surplus capacity of the CPU, image measurement, and the like can be performed. Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing an example of the overall configuration of a composite tomographic imaging apparatus according to the present invention. In order to obtain a tomographic image of the subject 1, the NMR imaging unit 4 or the X-ray CT unit 10
The subject is inserted into the opening of the gantry by moving the bed 2. The movement of the couch 2 is controlled by the couch control system 3 so that an operation for matching both slice positions can be performed.
The NMR imaging unit 4 includes a static magnetic field generating magnet 5, a sequencer 6, a transmitting system 7, a magnetic field gradient generating system 8, and a receiving system 9. The static magnetic field generating magnet 5 generates a strong and uniform static magnetic field around the subject 1 in a body axis direction or a direction orthogonal to the body axis, and has a certain space around the subject 1. A permanent magnet type, a normal conduction type, or a superconducting type magnetic field generating means is disposed in the apparatus. The sequencer 6 operates under the control of the CPU 16 and sends various commands necessary for data collection of tomographic images of the subject 1 to the transmission system 7, the magnetic field gradient generation system 8, and the reception system 9. The transmission system 7 performs amplitude modulation and amplification of the high-frequency pulse in accordance with the command of the sequence 6, and then applies the electromagnetic wave to the coil. The magnetic field gradient generating system 8 superimposes a gradient magnetic field in the three axes of X, Y, and Z on a static magnetic field. Depending on how the gradient magnetic field is applied, a slice plane for the subject 1 is set or a slice plane is set. It is responsible for converting the position information in the device into frequency information. The receiving system 9 detects an electromagnetic wave (NMR signal) of the response of the subject 1 due to the electromagnetic wave emitted from the transmitting system 7, performs A / D conversion, and samples the signal at a timing according to a command from the sequence 6. Then, the data is sent to the image processor 17. The X-ray CT unit 10 includes an X-ray control system 11, an X-ray generator 12, a detector 13, and a scanner control system.
14 and a squinana unit 15. The X-ray control system 11 operates the control of the CPU 16 and controls the X-ray generator 12 to generate a predetermined X-ray. The X-ray generator 12 is, for example, an X-ray tube, and radiates fan-shaped or linear X-rays directionally to a detection system 13 installed opposite thereto. At the same time, a scanner unit 15 having a pair of the X-ray generator 12 and the detection system 13 scans for rotation or translation under the control of a scanner control system 14 operating under the CPU 16. The detection system 13 converts the transmitted X-ray intensity of the subject 1 into an electric signal using photoelectric conversion, converts it into a digital value by A / D conversion, and sends it to the image processor 17. Signal processing
The console 15 includes a CPU 16, an image processor 17, a console 18, a display 19 such as a CRT, and a magnetic disk 20. The CPU 16 controls a series of processes such as image collection, recording, and display, and the image processor 17 controls the NMR and X-ray CT.
Are subjected to image reconstruction such as Fourier transform and various correction processes. The console 18 is a part for performing dialogue with an operator, such as input of parameters and IDs, execution / stop of processing, display of the status of the apparatus, and the like, and the magnetic disk 20 records image data and the like. In the case where an optical disk, a magnetic tape, or the like is used in addition to the magnetic disk 20 in the drawing, the effect of the present invention is not lost. FIG. 2 shows the appearance of the apparatus in the above embodiment. The bed 2 is NMR
This is a structure for inserting a patient into the gantry of the imaging unit 4 or the gantry of the X-ray CT unit 10, and includes a couch top 2a, a movable unit 2b, and a couch fixing unit 2c. The couch top 2a formed of a non-magnetic and non-conductive material slides on the couch and a patient can be inserted into both gantry, and the gantry is selected by the couch driving unit 3a, and the couch movable unit 2b rotates It is done by doing. In other words, the fixed plate 23 having the guide groove 22 which has a circular arc centered on the X-ray center and the rotation center 21 which is substantially the same distance from the center of the static magnetic field is fixed to the floor. The fixed plate 23 is provided with a non-rotating sprocket 24. The sprocket at the tip of the motor mounted on the movable part 2b is provided.
26 and chain 27. When the motor rotates in the direction of the arrow 28, the movable part 2b rotates in the direction 29 of the arrow. In addition, a roller 30 is attached to a lower portion of the movable portion to facilitate rotation. Operation console 18 has CP inside
Equipped with U16, image processor 17 and magnetic disk 20, the operator can perform all processing by operating only the console. The gantry of the NMR imaging unit 4 is a self-shielded type that suppresses the leakage of the magnetic field to the outside, and the X-ray CT unit near
The ferromagnetic material used in 10 prevents the magnetic field in the NMR imaging from being disturbed in the uniform space. In the present embodiment, the two gantry are arranged so that the angle between them in the non-sample axis direction is 90 °, but this angle can be freely selected from the permissible conditions of the facility and the product magnetization. [Effects of the Invention] According to the present invention, in a clinic where both an X-ray CT apparatus and an NMR imaging apparatus are required, (1) the space for one examination room can be saved, and the cost can be reduced. .
(2) The signal processing system and operation console can be omitted, and the cost can be reduced. (3) Two types of tomographic images need not be transferred and can be taken into the same image processing apparatus. (4) Since the patient does not need to be moved to use the same bed, the burden on the patient can be reduced and the positional correlation between the two images can be increased. (5) By performing the scanogram of X-ray CT in the NMR imaging unit, the exposure dose to the patient can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an example of the overall configuration of a combined tomographic imaging apparatus according to the present invention, and FIG. 2 is a diagram showing an appearance of the example of the overall configuration shown in FIG. 1 ... subject, 2 ... bed, 2a ... bed top, 2b ... bed movable section, 2c ... bed fixed section, 3 ... bed control section, 3a ...
... Bed driving section, 4... NMR imaging section, 5... Static magnetic field generating magnet, 6...
Magnetic field gradient generation system, 9 Reception system, 10 X-ray CT unit, 11
... X-ray control system, 12 ... X-ray generator, 13 ... Detection system, 14 ...
... Scanner control system, 15 ... Signal processing / operation console system, 16 ...
Central Processing Unit, 17 ... Imaging Processor, 18 ...
Operation console, 19 ... display, 20 ... magnetic disk.

Claims (1)

(57) [Claims] Means for applying a static magnetic field and a gradient magnetic field to the subject, means for applying a high-frequency pulse for causing nuclear magnetic resonance to the nuclei of the atoms constituting the tissue of the subject, and detecting a signal generated by the nuclear magnetic resonance A nuclear magnetic resonance imaging unit having a nuclear magnetic resonance signal detecting unit, an X-ray source provided to be capable of irradiating the subject with X-rays from a number of directions having different angles, and an X-ray source arranged to face the X-ray source ,
An X-ray CT imaging unit having an X-ray detection unit having a multi-channel configuration for detecting X-rays transmitted through the subject;
A single bed unit positioned at the imaging position of the CT imaging unit; a nuclear magnetic resonance signal detected by the nuclear magnetic resonance signal detecting unit or a transmission X detected by the X-ray detecting unit;
A single image reconstructing means for selectively reconstructing a tomographic image of the subject by using a line intensity distribution signal, the nuclear magnetic resonance imaging section, an X-ray CT imaging section, a couch means, and an image reconstructing means A single control unit for controlling the magnetic resonance image or the X-ray CT image reconstructed by the image reconstructing unit; and an insertion direction of the bed unit into the nuclear magnetic resonance imaging unit. Magnetic resonance imaging unit and X-ray CT so that the center line of the patient intersects the center line of the direction of insertion of the bed means into the X-ray CT imaging unit
A composite bed tomographic imaging apparatus comprising: a bed rotating unit that arranges an imaging unit and rotates the bed unit at the intersection position.