JP3310041B2 - Detector rotating 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 tomographic image of a subject based on a scintigram obtained by collecting signals from a detector for detecting gamma rays from the subject who has been administered a radiopharmaceutical. The present invention relates to a detector rotation type scintillation camera capable of creating and displaying an image.

[0002]

2. Description of the Related Art The construction and operation of a conventional detector-rotating scintillation camera will be described below with reference to FIGS. FIG. 6 is a block diagram schematically showing the configuration of a conventional detector-rotating scintillation camera, and FIG.
Is a flowchart for explaining the creation and display of one-frame scintigram of the conventional detector rotating scintillation camera, FIG. 8 is a flowchart for explaining the generation of tomographic images of the conventional detector rotating scintillation camera, and FIG. 9 is FIG. FIG. 10 is a diagram showing collection of a scintigram in which the heart is put in the field of view of the detector 1 in the detector rotating scintillation camera having the structure of FIG. FIG. 4 is a diagram showing collection of scintigrams out of one field of view.

First, the configuration of a detector-rotation type scintillation camera will be described with reference to FIG. The detector rotating scintillation camera includes a detector 1 in which a scintillator that receives a radiopharmaceutical and detects a gamma ray from a subject 2 supported on a bed 4 and converts the gamma ray into an electric signal is arranged along a two-dimensional plane. Position calculating means 5 for calculating the two-dimensional position of the gamma ray reaching the front surface of the container 1, a position expanding means 17 for expanding the position coordinates calculated by the position calculating means 5 at an arbitrary magnification, and this position Collecting means 6 for collecting a scintigram of a predetermined area (scintigram collecting area) from the gamma ray signals of the position coordinates enlarged by the enlarging means 17, and a display device which reads out the scintigram from the collecting means 6 and displays the scintigram 8, a detector gantry 3 connected to the detector 1 that enables the detector 1 to rotate around the subject, and a detector gantry 3 that rotates the detector 1 around the subject. To obtain a scintigram of rotation each angle, the data processing apparatus 21 for creating a tomographic image from their scintigram
The operation of the detector gantry 3 and the position expanding means 17,
It comprises a collecting means 6 and a CPU circuit 9 for controlling the display means 8.

Next, a process of creating and displaying a scintigram of one frame of a detector rotating type scintillation camera will be described with reference to FIG. The detector 1 detects a gamma ray from the subject 2 (Step 701). Detector 1
Has means for counting the number of gamma rays received within a certain time, and transmits the count value to the position calculating means 5 as a signal. The position calculation means 5 calculates a scintigram acquisition area from the signal of the detector 1 (Step 702). Here, the route differs depending on whether or not the display of the enlarged tomographic image is intended (step 703). When the purpose is an enlarged tomographic image, the position enlarging means 17 sets the scintigram acquisition area to the level of the Japanese Patent
The collection means 6 is enlarged as disclosed in
To enter. If an enlarged tomographic image is not intended, a signal of the gamma ray incident position is input to the collecting means 6 (steps 704 and 705). The collecting means 6 collects scintigrams as disclosed in JP-A-3-59488 (step 706). The scintigram is displayed on the display device 8 (step 707).

Next, the steps of creating and displaying a tomographic image of a detector rotating scintillation camera will be described with reference to FIG. The detector 1 can freely rotate around the subject 2 supported on the bed 4 by the detector gantry 3 linked to the detector 1. Therefore, a scintigram at an arbitrary angle can be created and displayed by rotating the detector 1. A plurality of different rotation angles of the detector 1 are set (Step 80)
1). The plurality of different scintigrams are created and displayed by the means shown in FIG. 7 (step 802). The created scintigram is transmitted to the data processing device 21 (step 8).
03). The data processing device 21 determines the possibility of creating a tomographic image from scintigrams obtained at different angles of the detector 1. For example, if a tomographic image cannot be created because the target organ is out of the field of view of the detector 1, steps 801 to 803 are repeated so as to try again until a tomographic image can be created. If a tomographic image can be created, the data processing device 21 creates and displays a tomographic image (steps 804 and 805).

[0006] The detector-rotating scintillation camera is used to obtain tomographic images of various parts of the subject 2, particularly the brain, heart, lungs, liver and the like, and those having a structure usable for the whole body are mainly used. In particular, a detector 1 having a large visual field is provided to obtain a tomographic image of a large-volume organ such as a lung or a liver. When attempting to obtain a tomographic image of a small-volume organ such as the brain or heart with a detector rotating scintillation camera having the detector 1 having a large visual field, the visual field of the detector 1 is too large as shown in FIG. Only small tomographic images can be obtained. For this reason, the detector 1 is
The arbitrary coordinates of the signal are enlarged and input to the collection unit 6 and the data processing device 21 creates a tomographic image, whereby a tomographic image having a size suitable for diagnosis can be obtained.

[0007]

However, according to the above-mentioned prior art, when a tomographic image of an organ having a small volume that is not on the body axis of the subject 2 as in the case of the heart shown in FIG. When the magnification is made around the axis (the rotation center of the detector), the position of the target organ in the field of view moves according to the rotation of the detector 1, so that the heart may be out of the field of view depending on the rotation angle. Reconstruction becomes impossible. For this reason, it is necessary to suppress the magnification of the position enlarging means 17 to the extent that the heart is not out of the field of view, and to generate a scintigram over a wide area including the heart. As a result, the tomographic image of the heart becomes small, There is a problem that a tomographic image of a heart having a size suitable for diagnosis cannot be obtained.

An object of the present invention is to provide a rotating detector type scintillation camera capable of displaying an enlarged tomographic image of an organ having a small volume such as the heart with high definition.

[0009]

An object of the present invention is to provide a detector in which scintillators for detecting gamma rays from a subject to which a radiopharmaceutical is administered and converting the gamma rays into electric signals are two-dimensionally arranged, and a scintillator arranged on a front surface of the detector. Position calculating means for calculating the two-dimensional position of the reached gamma ray, means for expanding the coordinates of the position calculated by the position calculating means at an arbitrary magnification, and gamma rays having the position coordinates expanded by the expanding means Collecting means for collecting a scintigram in a predetermined area (scintigram collecting area) from among the signals, a display device for reading out and displaying the scintigram from the collecting means, and the detector arranged around the subject. A detector gantry rotatably supported; a data processing device for rotating the detector around a subject to obtain scintigrams at a plurality of rotation angles to create a tomographic image; In a detector rotating type scintillation camera comprising control means for controlling a system including elements, a center position of a target organ of a subject is determined using a scintigram projected with the detectors arranged in arbitrary two directions ( Means for determining a rotation angle of the detector, a rotation angle detection means for detecting a rotation angle of the detector, and a scintigram collection area from the rotation angle of the detector detected by the rotation angle detection means and the coordinates of the expansion center point. This is achieved by providing means for calculating the amount of movement of the center of the image, and means for moving the scintigram collection area by the calculated amount of movement.
In the detector rotating type scintillation camera having this configuration, the means for determining the center position (enlargement center) of the target organ of the subject using the scintigram projected by arranging the detectors in any two directions includes: An orthogonal coordinate system is designated on a tomographic plane containing the target organ of the examiner, and a scintigram projected in two orthogonal axes is obtained, and a scintigram of one axis of the orthogonal coordinate system on the tomographic plane is obtained. Obtain the component of the other axis of the expansion center point, obtain the component of one axis of the expansion center point from the scintigram of the other axis, and calculate the center of the target organ of the subject from the components in both axial directions of the expansion center. Is calculated.

[0010]

The detector rotating type scintillation camera constructed as described above can also produce a scintigram in which a small organ deviating from the rotation center of the detector 1 is enlarged, and an enlarged high-definition tomographic image is obtained.

[0011]

【Example】

(Embodiment 1) Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
The description will be made with reference to FIG. FIG. 1 is a view for explaining the movement of the center of enlargement of the detector rotary scintillation camera of the present invention, FIG. 2 is a block diagram schematically showing the configuration of the detector rotary scintillation camera of the present invention, and FIG. FIG. 4 is a block diagram schematically showing the configuration of the moving and enlarging means 7 of the detector rotary scintillation camera, FIG. 4 is a flowchart showing the procedure for creating a tomographic image of the detector rotary scintillation camera of the present invention, and FIG. 5 is the configuration of FIG. It is a figure which shows collection of the scintillogram of a suitable magnification by the movement expansion means 7 of this invention in the case of a heart in a detector rotation type scintillation camera.

First, the process of calculating the center (center of enlargement) of the target organ of the subject 2 on the scintigram of the detector rotating scintillation camera of the present invention will be described with reference to FIG. FIG. 1A shows a two-dimensional plane including a cross section of a target organ of the subject 2 and is a plane perpendicular to the rotation axis of the detector 1. With the rotation center O of the detector 1 as the origin on this plane, the horizontal axis is the X axis, the vertical axis is the Y axis, the X axis is positive to the right as viewed in the drawing, and the Y axis is also positive downward. The angle increases clockwise so that the right side of the X axis is 0 ° and the lower side of the Y axis is 90 °. Now, assume that the center of the target organ to be enlarged (center of enlargement) is point A. In the case of the present invention, the operation of obtaining the coordinates of the enlarged center point A is performed by measuring the scintigrams 20a and 20b of the target organ when the detector 1 is arranged so as to be orthogonal to the X axis and the Y axis. Distance Ay and Ax between the center position of the gram and the X and Y axes
Is calculated. The distance R from the point O to the point A is calculated by Expression (1), and the angle α formed between the X axis and the line segment OA is calculated by Expression (2).

[0013] ^{R = (Ax 2 + Ay 2} ) 1/2 ······· (1)

Α = tan ^-1 (Ay / Ax) (2) FIG. 1B shows a case where the detector 1 is rotated from the target organ when the detector 1 is rotated around the subject 2. Scintigram 20 projected on
It shows how the center position of c changes.

When the scintillation camera attempts to observe an enlarged tomographic image of the target organ in an optimal state, it is sufficient to move the enlargement center to the rotation center and observe.
In the present invention, the point A ′, which is the projection of the enlarged center point A of the target organ to the detector 1, is moved to the point O ′, which is the projection of the rotation center O to the detector 1, for each rotation angle of the detector 1. Then, as shown in (b), taking the Y axis (negative direction) as a reference,
Movement amount D (= line segment O ') of projection point A' of expansion center point A
A ') is obtained from equation (3).

D = R · cos (α−β) (3) As described above, the projection point of the center of enlargement of the target organ is changed to the projection point of the rotation center for each rotation angle of the detector 1. Then, a scintigram enlarged at a magnification suitable for diagnosis at that point is created, this is repeated a plurality of times, and a tomographic image is reconstructed using those scintigrams, thereby obtaining the optimal tomographic image of the target organ for diagnosis. Images can be obtained.

The configuration of the detector rotation type scintillation camera according to the present invention will be described with reference to FIG. The detector rotating type scintillation camera of the present invention is shown in FIG.
In this embodiment, the position enlarging means 17 of the prior art detector rotary scintillation camera is replaced with the moving enlarging means 7 of FIG. 2 which can implement the present invention.

Next, the structure of the movement enlarging means 7 of the detector rotating type scintillation camera of the present invention will be described with reference to FIG. The moving and enlarging means 7 of the detector-rotating scintillation camera of the present invention is different from the position enlarging means 17 which is a conventional enlarging means by a distance R (= from the origin shown in FIG. 1B to the center of the target organ (enlarged center). OA), the angle α between the line segment OA and the X axis, the rotation angle β of the detector, and the line segment O′A ′ (= D) obtained by projecting the line segment OA on the front surface of the detector. (2) a moving amount calculating means 11 for calculating using the formula (3), and a center for receiving the transmission of the numerical value of D calculated by the moving amount calculating means 11 and moving the enlargement center at the rotation angle β by the numerical value. Shifting means 12, said enlarging means 17, moving amount calculating means 11, and center shifting means 12.
From the CPU circuit 9 to which a means for controlling the CPU is added.

Next, a process of creating and displaying a tomographic image having a magnification suitable for diagnosing a target organ by the detector rotating type scintillation camera of the present invention configured as described above will be described.

FIG. 1 shows the first step, ie, the step of measuring the center (enlargement center) point A of the target organ of the subject 2.
This will be described with reference to FIG. FIG. 1 (a)
, An orthogonal coordinate system is set on a tomographic plane including the target organ of the subject 2, the horizontal axis is the X axis, the vertical axis is the Y axis, the X axis is positive on the right side of the drawing, and the Y axis is similarly The lower part is positive. It is assumed that the angle increases clockwise so that the positive direction of the X axis is 0 ° and the positive direction of the Y axis is 90 °. At this time, the detector 1 is moved in the direction of 0 ° (step 401). At this detector position, gamma rays from the subject 2 are measured, a scintigram 20a projected on the detector 1 is created, and displayed on the display device 8.
(Step 402). The operator observes the scintigram of the target organ on the monitor of the display device 8 and specifies a point Ay ′ for specifying the Y component of the enlargement center by visually specifying the center position of the scintigram. The distance between the point Oy 'projected on the front surface of the detector and the line segment Oy'Ay' (that is, Ay) connecting the point Ay 'is calculated by the movement amount calculating means 11. In addition to the operator's visual specification of the center position of the scintigram, the means for specifying the point Ay 'can also specify the center position of the scintigram by measuring the histogram of the scintigram and calculating the position of the center of gravity. In the latter case, the point Ay 'can be automatically specified without the intervention of the operator (step 403). The detector 1 is moved in the direction of 90 ° (step 404). As in step 402, a scintigram 20b projected on the detector 1 is created and displayed on the display device 8 (step 405). Displayed on the monitor of the display device 8, a point Ax 'for specifying the X component of the enlargement center is specified, and a point Ox' obtained by projecting the rotation center O of the detector 1 on the front surface of the detector is specified in the same manner as in step 403. The distance of the line segment Ox'Ax '(that is, Ax) connecting the point Ax' is calculated by the movement amount calculating means (step 406). From the Ax and Ay calculated as described above, the distance of the line segment OA (= R) and the angle α formed between the line segment OA and the X axis by the movement amount calculating means 11.
Is calculated by Expressions (1) and (2) (Step 4)
07).

In the second step, one of the detectors 1
The process of creating an enlarged scintigram at one rotation angle will be described with reference to FIGS. 1 (b), 2, 3, and 4 (b). The detector 1 is moved by an arbitrary rotation angle β as shown in FIG. 1B (step 411). First
R, angle α, and rotation angle β of detector 1 calculated in steps
Is used to project the line segment OA to the front of the detector.
The distance of (= D) is calculated by the following formula (3).
Is calculated (step 412). Center shift means 12
Receives the numerical value of the movement distance D of the enlargement center from the movement amount calculating means 11 and the movement command from the CPU circuit 9, and moves the enlargement center from the point O 'to the point A' on the front surface of the detector and the scintigram collection area and data. Is moved (step 413). The position enlarging means 17 enlarges the position coordinates of the scintigram acquisition area by setting an enlargement ratio of the scintigram to be acquired centering on the point A '(step 414). The scintigram 20c collected by the collecting means 6 is created (step 41).
5). If a scintigram for obtaining an enlarged tomographic image is not to be created, the scintigram may not be passed through the moving magnification circuit 7 or the magnification may be set to 1.

FIG. 1 (b), FIG. 2 and FIG. 4 (c) show the final stage of the process of creating and displaying a tomographic image having a magnification suitable for diagnosing the target organ of the subject 2. It will be described using FIG. As shown in FIG. 1B, the detector 1 is set at the first rotation angle β (step 421). At this rotation angle, an enlarged scintigram is created using the process of the second stage (step 422). The rotation angle is updated while the detector 1 is rotated clockwise by a certain step angle, a scintigram enlarged by the rotation angle is created, and the subject 2
This step is repeated until one cycle is completed (step 42).
3,424,422). When the scintigram for one round of the detector has been taken, the scintigram is transmitted to the data processing device 21 (steps 423 and 425). The data processing device 21 creates a tomographic image and displays the enlarged high-resolution tomographic image of the target organ of the subject 2 on the display device 8 (step 426).

(Embodiment 2) In the first embodiment, by adding a storage means for storing a plurality of scintigrams in the configuration, a fixed angle can be obtained even if the detector 1 does not reach one rotation or one rotation. The plurality of scintigrams generated by the rotation up to are collectively stored in the storage means. After that, the center of the target organ (center of enlargement) by the movement amount calculating means 11
The calculation of the point and the calculation of the moving amount of the enlargement center at each rotation angle are collectively performed. Next, the center of enlargement is moved by the center shift means 12, and further enlarged to a required enlargement ratio by the position enlargement means 17 around the enlargement center point, and the scintigram for each rotation angle is collected by the collection means 6, Perform image reconstruction. According to the configuration and procedure described above, the first embodiment
In the same manner as the above, an enlarged high-resolution tomographic image of the target organ can be obtained.

(Embodiment 3) In Embodiments 1 and 2,
In the configuration of the detector rotating type scintillation camera shown in FIG. 3, the position enlargement means 17 and the center shift means 12 are exchanged, and a storage means having a larger storage capacity than the conventional one is added to the position enlargement means 17. In this configuration, the coordinates of the position calculated by the position calculating means 5 by the position expanding means 17 are enlarged at an arbitrary enlargement ratio, and the coordinates of the position enlarged by the position expanding means 17 are stored in the storage means. After that, the coordinates of the position enlarged by the position enlarging means 17 are read out from the storage means, and the movement amount calculating means 11 calculates the point at the center of the target organ (enlargement center) and calculates the movement amount of the enlargement center. This is performed for each rotation angle of the detector 1. Next, the center shift means 12 moves the center of enlargement similarly for each rotation angle. Further, collection of scintigrams in a predetermined area (scintigram collection area) among the coordinates of the position where the center of enlargement has been moved is similarly collected by the collection unit 6 for each rotation angle, and a tomographic image is reconstructed. . According to the configuration and procedure described above, an enlarged and high-resolution tomographic image of the target organ can be obtained as in the first and second embodiments.

(Embodiment 4) In the above-mentioned Embodiments 1 to 3, the CPU circuit 9 performs the calculations of the equations (1), (2) and (3) instead of the movement amount calculating means 11. It is also possible. In this case, the CPU circuit 9 performs an equation (1) for calculating a distance R from the rotation center point O of the detector 1 shown in FIG. 1B to the center (enlargement center) point A of the target organ. Equation (2) for calculating an angle α between the component OA and the X axis, and a line segment O′A ′ (that is, a center of enlargement) obtained by projecting a line segment OA that varies according to the rotation angle β of the detector 1 onto the detector 1 (3) calculated by the CPU circuit 9. As described above, even if the movement amount calculation part of the first to third embodiments is implemented by replacing the movement amount calculation means 11 with the CPU circuit 9, an enlarged high-resolution tomographic image of the target organ can be obtained.

[0026]

Since the present invention is configured as described above, it has the following effects. By attaching the movement expanding means 7, the detector 1
It is possible to create scintigrams at a large number of rotation angles enlarged around an arbitrary position according to the rotation of. The reconstructed scintigram obtains a tomographic image of an organ not at the rotation center of the detector 1. Can be. Therefore, as shown in FIG. 5, since a tomographic image of a small organ that is not at the center of rotation of the detector 1 such as a heart can be created at an optimum magnification, the details of the organ can be displayed on the screen, which facilitates diagnosis. Can be

[Brief description of the drawings]

FIG. 1 is a diagram showing a principle of a movement amount calculating means of a center of enlargement in a detector rotating type scintillation camera of the present invention.

FIG. 2 is a block diagram showing an embodiment of a detector rotating type scintillation camera of the present invention.

FIG. 3 is a block diagram of a movement enlarging means 7 in FIG. 2;

FIG. 4 is a flowchart showing an embodiment of a detector rotating type scintillation camera of the present invention.

FIG. 5 is a diagram showing an implementation of scintigram collection by the apparatus shown in FIG. 2;

FIG. 6 is a block diagram showing a conventional detector rotation type scintillation camera.

FIG. 7 is a flowchart illustrating scintillogram collection of a prior art detector rotating scintillation camera.

FIG. 8 is a flowchart showing tomographic image creation by a detector rotating scintillation camera according to the related art.

FIG. 9 is a diagram showing that a scintigram is collected by the apparatus shown in FIG. 6 and an enlarged tomographic image with a sufficient magnification cannot be obtained.

FIG. 10 is a diagram showing that scintigram collection is performed by the apparatus shown in FIG. 6 and an enlarged tomographic image of a part of an organ cannot be obtained.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Detector 2 Subject 3 Detector gantry 4 Bed 5 Position calculation means 6 Collection means 7 Movement expansion means 8 Display device 9 CPU circuit 11 Movement amount calculation means 12 Center shift means 17 Position expansion means 21 Data processing device

Continuation of the front page (56) References JP-A-4-36684 (JP, A) JP-A-55-121168 (JP, A) JP-A-4-270983 (JP, A) JP-A-62-2678 (JP, A) JP-A-61-18886 (JP, A) JP-A-61-160078 (JP, A) JP-A-3-108686 (JP, A) JP-A-54-124776 (JP, A) JP-A-1-152793 (JP, A) JP-A-1-118793 (JP, A) JP-A-63-52085 (JP, A) JP-A-5-11056 (JP, A) JP-A-63-135288 (JP, A) U) Tokuhyo Table 8-507858 (JP, A) (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01T 1/164

Claims (2)

(57) [Claims] 1. A scintillator for detecting a gamma ray from a subject to which a radiopharmaceutical is administered and converting the gamma ray into an electric signal.
Detector arranged in two dimensions, position calculating means for calculating a two-dimensional position of the gamma ray reaching the front of the detector, and means for enlarging the coordinates of the position calculated by the position calculating means at an arbitrary magnification rate And collecting a predetermined scintigram from the gamma ray signals having the position coordinates enlarged by the enlarging means.
Collecting means for collecting a scintigram of a region , a display device for reading and displaying the scintigram from the collecting means, a detector gantry rotatably supporting the detector around a subject, and the detector A data processing device for generating a tomographic image by obtaining a scintillogram at a plurality of rotation angles by rotating the device around a subject, and a control means for controlling a system including each of the above-described components. A means for obtaining a center of enlargement of a target organ of a subject using a scintigram obtained by arranging the detectors in any two directions and projecting the rotation in the camera; and a rotation angle detecting means for detecting a rotation angle of the detector. Means for calculating the amount of movement of the center of the scintigram collection area from the rotation angle of the detector detected by the rotation angle detection means and the coordinates of the enlargement center point; Detector rotary scintillation camera comprising comprising means for moving the moving amount by scintigraphy collection regions. 2. The apparatus according to claim 1, wherein the means for obtaining the enlargement center specifies an orthogonal coordinate system on a tomographic plane including the target organ of the subject, obtains a scintigram projected in two orthogonal axes, and obtains the tomographic image. From the scintigram of one axis of the orthogonal coordinate system on the plane, the component of the other axis of the enlargement center point is obtained, and from the scintigram of the other axis, the component of one axis of the enlargement center point is obtained. 2. The rotary scintillation camera according to claim 1, wherein coordinates of the center of the target organ of the subject are calculated from components in both axial directions.