JP3108446B2 - Scintillation camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scintillation camera for detecting a radiation emitted from a subject to obtain a tomographic image or a whole body image of the subject, and more particularly to a scintillation camera having a plurality of detectors.

[0002]

2. Description of the Related Art A scintillation camera is a device that detects radiation emitted from a radioisotope (hereinafter referred to as RI) in a subject and obtains a distribution of RI in the subject as a two-dimensional plane image. Further, the detector of the scintillation camera is moved along the body axis of the subject to obtain an RI distribution image of the whole body of the subject, and the detector is rotated around the subject to obtain the RI distribution in the subject. A tomographic image of the distribution can also be obtained. The time required to obtain these RI distribution images (hereinafter referred to as image acquisition time) is about 30 minutes for a scintillation camera with one detector. It is necessary to shorten the image acquisition time as much as possible in order to reduce the pain of the patient who is the subject, but since the image quality of the RI distribution image depends on the number of radiation detected by the detector, the image acquisition time is too short. Can not. Therefore, in recent years, a scintillation camera having a plurality of detectors for shortening the image collection time and improving the image quality of the RI distribution image has become popular. That is, by using a plurality of detectors, the number of radiations to be detected is substantially increased, and an attempt is made to shorten the image acquisition time and improve the image quality of the RI distribution image.

Conventional scintillation cameras having a plurality of detectors include those shown in FIGS. 4, 5 and 6. In the prior art shown in FIG. 4, four detectors 1 are mounted on a disk 2 and arranged in a square at an angle of 90 degrees. An object is inserted between these detectors 1 to collect images. When the disk 2 is driven to rotate around the axis 4 by driving means (not shown), each detector 1 rotates around the subject so that a tomographic image can be obtained. On the other hand, in the prior art shown in FIG. 5, three detectors 1 are arranged on a disk 2 in an equilateral triangle with an angle of 60 degrees with respect to each other. In the prior art shown in FIG. 6, two detectors 1 are arranged on a disk 2 so as to face each other. In each case, a tomographic image is obtained by rotating the detector 1 around the axis 4 by the disk 2 as in the conventional example of FIG.

In each of the conventional examples, the disk 2 is attached to the stand 3 so as to be rotatable around an axis. Further, a device having a driving means for moving the entire stand 3 in the horizontal direction along the body axis of the subject or a detector 1 on the disk 2 as indicated by an arrow a
Some have detector moving means for moving the object closer to or farther from the axis 4.

[0005]

By the way, as described in the prior art, in clinical application of a scintillation camera, in addition to diagnosis using a tomographic image, radiation from a subject is detected without rotating a detector, and There is a method of two-dimensionally capturing the RI distribution in the inside as a two-dimensional image and performing diagnosis based on the two-dimensional image. For example, in order to see the distribution of RI accumulated in the bone of the subject, the detector is moved in the body axis direction of the subject to obtain an RI distribution image of the whole body of the subject, and diagnosis is performed based on the RI distribution image. Clinical applications are widely practiced. However, since the radiation emitted from the RI administered into the body is absorbed inside the subject, it is necessary to obtain RI distribution images from both the front and back of the subject even when diagnosing a planar image. There is.

FIG. 7 shows a method of obtaining an RI whole body distribution image of a subject 6 lying on a bed 5 with two detectors according to the prior art shown in FIG. The detector 1 is moved on the disk 2 so as to approach the subject 6. The reason for moving the detector 1 is that if the detector 1 is brought as close as possible to the imaging region,
Due to the characteristics of the collimator 7 attached to the detection surface of the detector 1,
This is because radiation incident on the detector 1 at a fixed angle from the imaging region can be accurately detected, and the resolution of the RI distribution image increases. Next, the stand 3 moves horizontally to move the detector 1 along the body axis of the subject 6 as indicated by an arrow b, so that the RI whole body distribution images of the front and back of the subject 6 can be obtained at the same time. The prior art shown in FIG. 4 also uses the upper and lower opposing two detectors 1 among the four detectors to obtain the object 6.
Can simultaneously obtain the RI distribution images from the two directions of the front and the back, so that the image acquisition time can be shortened and the image quality of the RI distribution images can be improved.

On the other hand, the prior art shown in FIG. 5 has three detectors 1 to obtain a planar image of the whole body of the subject 6, but the detectors are arranged in an equilateral triangle. Since one of the detectors 1 collects the RI distribution image of either the front or the back, the detector (or another detector) is positioned at the other of the front and the back. Therefore, the RI distribution image in the remaining direction must be collected by the detector, so that it takes a long time to collect the image as in the case of the scintillation camera having one detector, and there is a problem that the image collection efficiency is poor. . Therefore, the conventional example of FIG. 4 and the conventional example of FIG. 6 are advantageous for obtaining RI distribution images from both the front and back directions of the subject.

Next, in the case where the detector 1 is rotated around the subject 6 to obtain a tomographic image of the RI distribution in the subject 6, the larger the number of the detectors 1, the greater the distance from the subject 6. It is advantageous in terms of the efficiency of detecting emitted radiation. However, since the image quality of the RI distribution image depends not only on the number of detected radiations but also on the resolution of the RI distribution image,
It is necessary to bring the detector 1 as close as possible to the target site of the subject 6. The reason for bringing the detector 1 closer to the target part of the subject 6 is that, as described above, when the detector 1 is brought as close as possible to the imaging part, due to the characteristics of the collimator 7 attached to the detection surface of the detector 1, the detector This is because radiation incident at a fixed angle from the imaging region with respect to 1 can be accurately detected, and the resolution of the RI distribution image increases. FIG. 8 shows a method of obtaining an RI distribution tomographic image of the head of the subject 6 with three detectors using the conventional technique shown in FIG.

In FIG. 8, three detectors 1 are moved by a detector moving means to a position where they come into contact with each other as shown by an arrow c, and the head is positioned between the three detectors 1, and thereafter the detection is performed. The container 1 is rotated by the driving of the disk 2 as shown by an arrow d. When obtaining a tomographic image of the body of the subject 6, as shown in FIG. 9, each detector 1 is moved as shown by an arrow e so as to secure a space where the subject 6 can enter. Then, the target part of the subject 6 is positioned between the detectors 1 and thereafter, the detector 1 is rotated to obtain a tomographic image of the heart or the like.

[0010] In the prior art shown in FIG. 6 as well, the two detectors are brought as close as possible to the target site of the subject 6, and the R with high resolution is obtained.
An I distribution image is obtained. However, the effect of detecting radiation radiated from the subject 6 is inferior to that of the conventional example of FIG. 5 due to the smaller number of detectors 1.

On the other hand, in the conventional example shown in FIG.
When four detectors 1 having a large detection field of view are used according to the body of the subject, the detector 1 cannot be brought as close as possible to the head of the subject 6, so that the RI distribution with good resolution can be obtained. There is a problem that an image cannot be obtained. Conversely, when four detectors 1 having a small detector field of view are used so as to be as close to the head of the subject 6 as possible, the detection field of view of the body of the subject 6 is small and unsuitable. Therefore, the conventional example shown in FIG.
Although the efficiency of detecting the field line radiated from the subject 6 is high, there is a problem in versatility since an apparatus having a different detection field of view is required for each target portion of the subject 6. An object of the present invention is to provide a multi-detector scintillation camera which eliminates the above problems.

[0012]

In order to achieve the above object, the present invention provides a stand, stand moving means for moving the stand in the body axis direction of a subject, and a rotating circle supported by the stand. A plate, a rotary driving means for driving the rotary disk to rotate around the subject, a detector movably mounted on the rotary disk, and a detection device for moving the detector on the rotary disk. A scintillation camera having a detector moving means, wherein the detector has a detection field of view large enough to obtain an RI distribution image of the body of the subject and two large-field detectors arranged opposite to each other. And said 2
Two small field-of-view detectors which are arranged at positions facing each other in a direction perpendicular to the opposing axis of the large field of view detectors and have a detection field of view which is about half the size of the field of view of the large field of view detector,
The detector moving means moves the two detectors in the large field of view away from or near the rotation axis of the rotating plate, and moves the two detectors in the small field of view up, down, left and right, Alternatively, it is a moving unit that moves obliquely with respect to the rotation axis. When the large-field detector and the small-field detector are rotated around the body of the subject, the detector moving means makes contact with the fields of view of the two small-field detectors and the large-field detector. The small-field detector is moved so that a line connecting the end on the non-use side passes through the rotation axis of the rotating plate.

[0013]

As described above, the detector is composed of two detectors having a large field of view and two detectors having a small field of view, and the four detectors are brought as close as possible to the head of the subject. Thus, a tomographic image of the RI distribution can be obtained. With respect to the body of the subject, two detectors of a small field of view are arranged facing each other so as to correspond to the right half and the left half of the field of view of the detector of the large field of view, respectively.
A tomographic image of the RI distribution can be obtained with the same radiation detection efficiency as the three large-field detectors. In this case, since the two detectors in the small field of view face each other, the same RI distribution image as that of the detector in the large field of view cannot be obtained at a time, but one of the small field of view detectors is 180 ° from the initial position. When rotated, the detector comes to the position of the other half of the detection field of view of the other opposing small-field detector, whereby an RI distribution image of the same size as the large-field detector is obtained. In addition, when obtaining the RI distribution image of the whole body, since the two detectors having a large field of view are opposed to each other, it is possible to simultaneously obtain the RI distribution images from two directions of the front and back of the subject.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a configuration diagram showing an embodiment of the scintillation camera according to the present invention, and shows a case where a tomographic image of the RI distribution of the body of the subject 6 is obtained. FIG. 2 and FIG.
7A and 7B are explanatory diagrams for obtaining a tomographic image of the head of a subject 6 and an RI distribution image of the whole body, respectively.

The scintillation camera of the embodiment includes two opposing detectors 1a and 1b having a detection field of view large enough to obtain an RI distribution image of the body of the subject 6, and the two detectors. The two detectors 1c and 1d, which are arranged at positions facing each other in a direction perpendicular to the opposite axis and have a detection field of view of about half of the detector, are mounted on the disk 2, and the disk 2 is located at its center. This is a configuration attached to the stand 3 so as to be rotatable around an axis. Detector 1
The lines c and 1d are arranged so that the line connecting the end of the detection visual field on the side not in contact with the detector 1a passes through the rotation axis of the disk 2.
In FIG. 1, the detectors 1a and 1b are moved on the disk 2 so as to move away from or closer to the rotation axis as indicated by an arrow f by a detection moving means (not shown). The detectors 1c and 1d are moved obliquely with respect to the rotation axis as shown by an arrow g on the disk 2 by a detector moving means (not shown). The detector moving means of the detectors 1c and 1d has a complicated structure, but may be moved obliquely with respect to the rotation axis by moving the detectors 1c and 1d up, down, left and right on the disk 2.

In such a configuration, when a tomographic image of the body of the subject 6 is obtained, as shown in FIG. 1, the detectors 1a, 1b, 1c, and 1d are provided with a space in which the subject 6 can enter. Are arranged so as to secure the position of the subject 6, and the target portion of the subject 6 is positioned between the detectors. At a certain rotation angle, the RI distribution image collected by the detectors 1c and 1d is
When the detectors 1c and 1d come to the positions of 1c 'and 1d', respectively, after being rotated by 180 degrees from the rotation angle, the detection field of the other half of the detector 1c at the first rotation angle. Corresponds to 1d ', and 1c' corresponds to the position of the detection field of the other half of the detector 1d. By joining both RI distribution images, an RI distribution image having the same size as the detectors 1a and 1b is obtained. Can be As a result, the detectors 1c and 1d
Are equivalent to one large-field detector.

Next, a case where a tomographic image of the RI distribution of the head of the subject 6 is obtained by this embodiment is shown in FIG. Detector 1
a and 1b are installed as close as possible to the head of the subject 6 as shown by an arrow h, and detectors 1c and 1d are installed as close as possible to the head of the subject 6 as shown by an arrow i. . FIG. 3 shows a case where an RI distribution image of the whole body of the subject 6 is obtained according to this embodiment. The detectors 1c and 1b are moved away from the position where they do not hinder the movement of the detectors 1a and 1b as indicated by an arrow j, and the detectors 1a and 1b are moved away from the object 6 as indicated by an arrow k.
It is installed as close as possible to Next, as in the conventional example of FIG. 7, the stand 3 is moved horizontally by driving means (not shown), and the detectors 1a and 1b are moved along the body axis of the subject 6, so that the front and the back of the subject 6 are moved. RI
A whole-body distribution image can be obtained at the same time.

[0018]

Since the present invention is configured as described above, when obtaining a tomographic image of the RI distribution of the head of the subject, 4
When a tomographic image of the RI distribution of the body of the subject is obtained with the radiation detection efficiency of the detector, an RI distribution image can be collected with the radiation detection efficiency of three detectors, and the RI distribution of the whole body of the subject can be obtained. In the case of obtaining an image, two detectors with a large field of view facing each other can simultaneously collect RI distribution images from both the front and back directions of the subject, so that it has versatility applicable to each target site of the subject, and This has the effect of providing a scintillation camera capable of shortening the image collection time and improving the image quality of the RI distribution image.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram when a tomographic image of an RI distribution of a head of a subject is obtained.

FIG. 3 is an explanatory diagram for obtaining an RI distribution image of the whole body of a subject.

FIG. 4 is an overall perspective view showing a configuration example of a conventional scintillation camera.

FIG. 5 is an overall view showing another example of a conventional scintillation camera.

FIG. 6 is an overall view showing another example of a conventional scintillation camera.

FIG. 7 is an explanatory diagram in the case where an RI distribution image of the whole body of a subject is obtained by the conventional example in FIG. 6;

8 is an explanatory diagram of a case where a tomographic image of a subject's head is obtained by the conventional example of FIG. 5;

9 is an explanatory diagram of a case where a tomographic image of a body part of a subject is obtained according to the conventional example of FIG. 6;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Detector 2 Disc 3 Stand 4 Rotation axis 5 Bed 6 Subject 7 Collimator 1a, 1b Large-field detector 1c, 1d used in the present invention Smaller field of view than the detectors 1a, 1b used in the present invention Detector

Claims (4)

(57) [Claims] 1. A stand and a body axis of the subject.
A stand moving means for moving in the direction,
A supported rotating disk, and rotating the rotating disk around the subject.
A rotating drive means for rotating the rotating disk;
A detector movably mounted on the rotating disk;
Scintillation with detector moving means moving on it
In the camera, the detector is provided with the R of the body of the subject.
Have a detection field of view large enough to obtain an I distribution image
Two large-field detectors arranged in a horizontal direction, and the two large-field detectors
Located at a position perpendicular to the opposite axis of the detector
Having a smaller detection field of view than the large field of view detector
Comprising a plurality of small field-of-view detectors, wherein the detector moving means comprises:
The large field of view detector and the small field of view detector
It is a means of moving closer to or away from
The scintillation camera to be used. 2. When the detector is rotated around a body of a subject, the detector moving means comprises:
Claims the line connecting the ends of the side where the field of view of the small field of view detector said not in contact with the large field of view detector is characterized in that moving the small visual field detector so as to pass through the rotation axis of said rotating plate Item 1
Scintillation camera according to. 3. The detector moving means includes means for moving the two detectors in the large field of view away from or near the rotation axis of the rotary plate, and moving the two detectors in the small field of view up, down, left and right. scintillation camera according to claim 1 or moves, or characterized by comprising moving means for moving obliquely relative to the axis of rotation. 4. The size of the field of view of the small field of view detector is approximately half the size of the field of view of the large field of view detector.
The scintillation camera according to claim 1 , wherein