JP3350142B2 - Nuclear medicine diagnostic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention, along with the subject radiation
Move the detection means and radioisotope administered to the subject
The present invention relates to a nuclear medicine diagnostic apparatus for obtaining element distribution .

[0002]

2. Description of the Related Art When a radiopharmaceutical labeled with a radioisotope (radioisotope; hereinafter, simply referred to as "RI") is administered to the body, the radiopharmaceutical concentrates on a specific organ or tissue determined by the properties of the drug. The scintillation camera is a device that is useful for diagnosis that detects γ-rays emitted from the RI inside the body outside the body and obtains the RI distribution inside the body to image the shape and function of the organ, the presence or absence of a lesion, and the metabolic function. ,
Despite problems such as poor resolution and exposure, it has its own fields such as early detection of cerebral ischemia and the possibility of survival of cells in myocardial infarction, and its complementary role to X-ray CT and MRI Plays.

[0003] Conventional scintillation cameras are as follows.
The detector along the body axis of the subject
I was going for a fortune.

In a first method, as shown in FIG. 15A, the height of a detector 100 is determined based on the highest level of a ridgeline indicating undulation from the side of a subject P before data collection. performs scanning by the detector 100 and remain within the height <br/> be horizontally moved.

In the second method, as shown in FIG. 15B, the detector 100 is moved along the ridge line of the subject P once before the data collection, and the trajectory is memorized. Therefore, the whole body scan is performed by moving the detector 1.

However, the above method has the following problems. The first is to use the detector 100 prior to data collection.
It is necessary to determine the height of the object. Furthermore, in many parts other than the highest position, the distance between the detector and the subject is too large, so that the resolution is reduced.

[0007] A second method is to use a detector 10 before data collection.
It takes time to remember the zero trajectory. Furthermore, it cannot respond to the movement of the subject during data collection. That is, if the subject moves while the detector is moving on the predetermined trajectory, the detector may come into contact with the subject, and the collection operation is stopped urgently each time.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to eliminate the need for advance preparations for data collection and to maintain sufficient distance from a subject while maintaining a predetermined distance. It is an object of the present invention to provide a nuclear medicine diagnostic apparatus capable of improving the resolution by collecting data and improving the resolution, and maintaining a predetermined distance by appropriately responding to the movement of the subject.

[0009]

According to the present invention, the following means are provided to solve the above-mentioned object. The invention according to claim 1 includes a radiation detector that detects radiation emitted from a radioisotope administered to a subject, and rotating the radiation detector with respect to the subject or a body axis of the subject. A moving mechanism for moving the radiation detector along with the subject, a separation approach mechanism for separating or approaching the radiation detector with respect to the subject, a sensor for detecting a distance of the radiation detector with respect to the subject, and a sensor for the subject. When the radiation detector approaches a predetermined distance or less, start the separating operation of the radiation detector for the subject, when the radiation detector exceeds the predetermined distance for the subject, the The separation operation of the radiation detector is stopped, and when a predetermined time has elapsed from the stop of the separation operation, the approach operation of the radiation detector to the subject is started based on the output of the sensor. A control circuit for controlling said separating approaching mechanism had,
It is characterized by having. The invention according to claim 2 is a radiation detector for detecting radiation emitted from a radioisotope administered to a subject, and rotating the radiation detector with respect to the subject or the body of the subject. A moving mechanism that moves along an axis, a separation approach mechanism that separates or approaches the radiation detector with respect to the subject, a sensor that detects the distance of the radiation detector with respect to the subject, On the other hand, when the radiation detector approaches a predetermined distance or less, the separation operation of the radiation detector is started with respect to the subject, and when the radiation detector exceeds the predetermined distance with respect to the subject. Stopping the separating operation of the radiation detector, and moving the radiation detector by the moving mechanism along the body axis direction by rotating a specific distance with respect to the subject from the stop of the separating operation. The to initiate the approach movement of the radiation detector to the subject, characterized by comprising a control circuit for controlling said separating approximation mechanism based on the output of the sensor.

[0010]

The following effects are obtained as a result of taking the above measures. According to the first aspect of the present invention, when the radiation detector approaches the object less than a predetermined distance, the radiation detector is started to move away from the object, and the radiation detector exceeds the predetermined distance. The radiation detector is stopped, and when a predetermined time has elapsed from the stop of the radiation operation, the approach operation of the radiation detector is started, so that the detector can be brought closer to the subject. it can. According to the second aspect of the present invention, when the radiation detector approaches the object within a predetermined distance or less, the radiation detector is started to separate from the object, and the radiation detector is moved to the predetermined distance. When the radiation detector moves beyond a certain distance from the subject or moves along the body axis direction when the radiation detector stops moving, the radiation detector stops moving. Is started, the detector can be brought closer to the subject.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing a detector, which is a main structure of a scintillation camera as an example of a nuclear medicine diagnostic apparatus, and a supporting mechanism thereof.

The two stand rails 1 are laid in parallel with the floor. A stand 2 is movably engaged with the stand rail 1 along a direction A. During data collection, the body axis of the subject is kept parallel to the direction A. On one side surface of the stand 2, a rotating plate 3 that rotates in the direction B is provided. A detector 5 is mounted near the periphery of the rotating plate 3 via an arm 4. The detector 5 rotates around the isocenter a with the rotation of the rotating plate 3.
The arm 4 includes a detector separation / proximity mechanism (not shown).
The detector 5 is moved in the direction C by the detector separation / proximity mechanism. Note that the direction C is a direction that is separated from or approaches the subject.

The detector 5 has a detection surface (γ
A sensor for detecting that the line incident surface) has approached the object surface to a predetermined fixed distance is attached. As this sensor, various sensors described below are selectively applied.

FIGS. 2A and 2B show examples of application of the ultrasonic sensor. FIG. 2A is a side view of the detector 5 equipped with the ultrasonic sensor, and FIG.
FIG. 5 is a view of the detector 5 on which the ultrasonic sensor is mounted as viewed from below. A plurality of ultrasonic sensors 6 are arranged side by side along the width direction of the subject P (hereinafter simply referred to as “direction D”) on the front and rear sides of the movement of the detector 5. The ultrasonic sensor 6 measures a distance based on a time difference from transmission of an ultrasonic wave to reception of the reflected wave, and outputs a detection signal when the distance reaches the predetermined distance. In the following description, a state when the detection signal is output, in other words, a state when the detection surface of the detector 5 approaches the subject P to a certain distance is referred to as an ON state, and the detection signal is not output. The state at the time, in other words, the state when the detection surface of the detector 5 is separated from the surface of the subject P by a certain distance or more is OFF.
It is referred to as a state. Unless otherwise specified, the definitions of the ON state and the OFF state are common to sensors described later.

FIG. 3 shows an application example of the reflection type optical sensor. FIG. 3 shows a detector 5 equipped with this reflection type optical sensor.
It is the figure which looked at from the side. The reflection type optical sensor 7 measures a distance by emitting light and receiving the reflected light, and outputs a detection signal when the distance reaches a predetermined distance. The plurality of reflective optical sensors 7 are
Similarly to the above, the detector 5 is arranged side by side along the direction D on the front and rear sides of the movement of the detector 5.

FIG. 4 shows an application example of the air mat sensor. FIG. 4 is a side view of the detector 5 equipped with the air mat sensor. The air mat 8 included in the air mat sensor is filled with air at a constant pressure and is mounted on the entire detection surface of the detector 5 with a constant thickness. This thickness is set to be the same as a certain distance when the ultrasonic sensor or the reflection type optical sensor outputs a detection signal. The air mat sensor includes a pressure sensor that detects a change in the pressure of the air mat 8 and outputs a detection signal. When the air mat 8 comes into contact with the subject P, the air pressure changes. In response, the barometric pressure sensor outputs a detection signal.

FIGS. 5A, 5B and 5C show examples of application of a tension sensor. FIG. 5A is a side view of the detector 5 equipped with the tension sensor.
5B is a diagram of the detector 5 equipped with the tension sensor as viewed from the head of the subject P, and FIG. 5C is a diagram of the detector 5 equipped with the tension sensor as viewed from below. Below the detection surface of the detector 5, a string 10 is stretched with a constant tension in parallel with the direction D, as shown in FIG. The string 10 is stretched at a fixed distance from the detection surface of the detector 5. This distance is set to be the same as a certain distance when the ultrasonic sensor or the reflection type optical sensor outputs a detection signal. A plurality of the strings 10 are prepared and arranged at equal intervals. Each string 10 is provided with a tension sensor 9. String 10
Is in contact with the subject P, the tension changes. Each tension sensor 9 detects a change in the tension of the corresponding string 10 and outputs a detection signal. Note that the plurality of strings 10 can be substituted for cloth.

FIGS. 6 (a), 6 (b) and 6 (c) show examples of the application of a facing optical sensor. FIG. 6 (a) is a side view of the detector 5 equipped with the facing sensor, and FIG. 6 (b) is a detector 5 equipped with the facing sensor.
FIG. 6C is a diagram of the detector 5 as viewed from the head of the subject P, and FIG. The facing sensor includes a light emitting element 11 and a light receiving element 12 facing the light emitting element 11. The plurality of light emitting elements 11 are arranged in parallel along one direction A on one side surface of the detector 5. Accordingly, a plurality of light receiving elements 12 are arranged on the other side surface of the detector 5 along the direction A. The light emitting element 1 is arranged such that the optical axis (dotted line) from the light emitting element 11 to the light receiving element 12 opposed thereto is separated from the detection surface of the detector 5 by a certain distance.
1 and the position of the light receiving element 12 are set. This distance is set to be the same as a certain distance when the ultrasonic sensor or the reflection type optical sensor outputs a detection signal. Light emitting element 1
When the light from 1 is shielded by the subject P, the output of the light receiving element 12 decreases. The state at this time is called an ON state, and when the light from the light emitting element 11 is received by the light receiving element 12 without being blocked, the output from the light receiving element 12 indicates the expected intensity. The state at this time is called an OFF state.

FIGS. 7A and 7B show another application example of the opposed-type optical sensor. FIG. 7A is a diagram of the facing sensor viewed from the side, and FIG. 7B is a diagram of the facing sensor viewed from the head of the subject P. A plurality of light emitting elements are arranged one-dimensionally at equal intervals to form a light emitting element array 13. Similarly, a plurality of light receiving elements are arranged one-dimensionally at equal intervals to form a light receiving element array 14. A plurality of (three in the figure) light emitting element arrays 13 are installed on the floor along the direction A. A plurality of light receiving element arrays 14 face each light emitting element array 13 and
At an interval exceeding the width of the subject P and the detector 5 from
It is installed on the floor along the direction A. Light emitting element array 13
The light emitting element array 13 and the light receiving element array 14 are arranged such that the optical axis (dotted line) from each of the light emitting elements to the light receiving element of the light receiving element array 14 opposed thereto is a parallel line at equal intervals along the direction C. Provided. When the light from the light emitting element is blocked by the subject P, the output of the light receiving element facing the light decreases. The distance between the detection surface of the detector 5 and the subject P is recognized by the combination of the light receiving elements whose output does not decrease. This is because the distance between the optical axes is set to a predetermined distance. The state when the distance between the detection surface of the detector 5 and the subject P reaches a certain distance is called an ON state,
OFF when this distance exceeds a certain distance
State. The distance in the ON state is the same as a certain distance when the ultrasonic sensor or the reflection type optical sensor outputs a detection signal. Note that the light emitting element array 13 and the light receiving element array 14 may not be installed on the floor surface, but may be mounted on the side surface of the detector 5 and move together with the detector 5. Further, in this reflection type sensor, at least one pair of the light emitting element and the light receiving element moves along the direction C without scanning the light emitting element and the light receiving element, and the light is used to scan the subject P from the side. May be used.

As described above, in this embodiment, any of the plural types of sensors shown in FIGS. 2 to 7 may be selectively applied. Therefore, any of the applied sensors is hereinafter referred to as a “sensor”.

FIG. 8 is a block diagram of a main part of this embodiment. The sensor control circuit 16 drives the sensing operation of the sensor 15 and turns the sensor 15 on or off.
Detect or recognize the condition. The gantry control circuit 17 receives the ON state or the OFF state of the sensor 15 detected or recognized by the sensor control circuit 16 and moves the stand 2 shown in FIG. , A control signal is output to the detector separation / proximity driving unit 19 for separating or approaching the detector 5 with respect to the subject P, and the movement thereof is controlled.

Next, the operation of the present embodiment configured as described above will be described. FIG. 9 is a schematic diagram illustrating an operation of obtaining the body axis of the subject P. First, as the rotating plate 3 rotates, the detector 5 makes one rotation around the subject P through the 90 ° position, the 180 ° position, and the 270 ° position in order from the 0 ° position. At each position, the rotation of the rotating plate 3 stops. At this time, the detector 5 approaches the subject P by driving the detector separation / proximity drive unit 19. When the detector 5 approaches the subject P to a predetermined distance, the sensor 15 is turned off.
The state is switched from the ON state to the ON state. At this time, the detector 5 stops because the driving of the detector separation / proximity drive unit 19 stops. Position of detector 5 at this time (X coordinate and Y coordinate on XY coordinate space centered on isocenter a)
Is measured. In the drawing, dy1 and dy2 indicate the Y coordinate of the detector 5 when the detector 5 is at the 0 ° position and the 180 ° position, respectively. Dx1 and dx2 indicate the X-coordinates of the detector 5 when the detector 5 is at the 90 ° position and the 270 ° position, respectively. The X coordinate dx and the Y coordinate dy of the body axis O on the XY coordinate space can be obtained by the following equations (1) and (2), respectively.

Dx = (dx1 + dx2) / 2 (1) dy = (dy1 + dy2) / 2 (2) In this manner, the position of the body axis O of the subject P is obtained. By moving the top plate up, down, left, and right, and displacing the subject P on the top plate, the isocenter a can be made to coincide with the body axis O of the subject P.

Next, the positioning operation at the start of scanning will be described. This alignment means that the detector 5 is connected to the subject P
Means approaching the target site to a predetermined distance. First, position information of a target part is set from a console (not shown). By moving the stand 2 in accordance with this position information, the detector 5 is moved to a position facing the target site. The detector 5 is moved closer to the subject P by driving the detector separation / proximity driver 19 at this position. When the detector 5 approaches the subject P to a predetermined distance, the sensor 15 switches from the OFF state to the ON state. In response to this ON state, the detector separation / proximity drive unit 19 ends the proximity operation of the detector 5. Detector 5
Is moved to a position facing a preset target portion, the stand 2 stops. Therefore, the alignment is completed without making the operator aware of the contact between the detector 5 and the subject P.

Next, a scan operation when actually collecting data will be described. FIG. 10 is a flowchart showing the flow of this scanning operation. First, position information for ending the scan is set from a console (not shown). Then, the movement of the stand 2 is started by the stand movement driving unit 18, and accordingly, the horizontal movement of the detector 5 is started (step S11). Note that the γ-ray detection operation by the detector 5 is continued during the scan period. Also,
During the scanning period, the horizontal movement of the detector 5 is also continued.

During this scanning period, the state of the sensor 15 is checked at any time by the sensor control circuit 16 (step S12). Here, when the sensor 15 is in the OFF state, that is, when the detector 5 is separated from the subject P beyond a predetermined distance, the detection separation / proximity driving unit 19 causes the detector 5 to approach the subject P. The operation is started (step S
13). This proximity operation is continued while the sensor 15 is in the OFF state (Step S14). The proximity operation is stopped when the sensor 15 switches from the OFF state to the ON state and the detector 5 approaches the predetermined distance from the subject P (step S15).

As soon as the approaching operation is stopped, a separating operation in which the detector 5 separates from the subject P is started by the detector separating / approaching drive unit 19 (step S16). This separation operation is continued while the sensor 15 is in the ON state (step S17). Further, the separating operation is continued until a predetermined time has elapsed from the time when the sensor 15 is switched from the ON state to the OFF state (Step S18), and is ended (Step S19). Subsequently, the process returns to step S13 to start the proximity operation.

Here, from step S16 to step S16
The operation up to 19 will be specifically described with reference to FIG.
In the figure, a solid line indicates a ridge line of a part of the subject, and a dotted line indicates a trajectory of the detector 5. In the figure, d1 is the step S
Reference numeral 15 indicates the position of the detector 5 when the separating operation is started, d2 indicates the position of the detector 5 when the sensor 15 switches from the ON state to the OFF state in step S16, and d3 indicates the position when the switching is performed. 3 shows the position of the detector 5 when a certain time has elapsed from the time shown in FIG. That is, here, instead of immediately moving to the proximity operation when the sensor 15 is turned off, the separation operation is continued until a certain time has elapsed since the sensor 15 was turned off, and then the operation moves to the proximity operation. As a result, a jerky unnecessary operation in which the detector 5 repeatedly repeats the separating / proximity operation,
So-called inching operation can be prevented.

After the above operation, the scanning operation is completed when the detector 5 reaches the preset scanning end position. As described above, when changing from the separation operation to the proximity operation, the separation operation is continued until a certain time has elapsed since the sensor 15 was turned off, thereby preventing the inching operation. A method for preventing the above will be described below.

FIG. 12 is a flowchart showing the flow of the scanning operation including the preferred inding prevention operation. In FIG. 12, the same steps as those in FIG. 10 are denoted by the same reference numerals, and description thereof will be omitted. However, this preferable anti-inching operation can be performed when any of the sensors shown in FIG. 5 or FIG. 6 is employed. Here, the facing optical sensor of FIG. 6 will be described as an example.

In this operation, in step S17, the output of at least one light receiving element 12 is changed from the ON state to the OF state.
When the state is switched to the F state, the separating operation is stopped. However, immediately after the stop, the proximity operation (step S13)
Instead, the proximity operation is not performed until a predetermined condition is satisfied in step S21. This condition is that a predetermined time has elapsed since at least the output of the light receiving element 12 was switched from the ON state to the OFF state in the immediately preceding step S17, or the distance from the position of the frontmost light receiving element 12 that was switched to the ON state. The condition is that at least one of whether or not L has been moved is satisfied. FIG.
Is a diagram for explaining this distance L. In the figure, A 'indicates the horizontal movement direction of the detector 5, that is, the detector 5 moves from the head side of the subject P toward the foot.
When any part of the detection surface of the detector 5 approaches the subject P to a predetermined distance while the detector 5 is moving horizontally, the output of at least one light receiving element 12 in that part is turned on. . The distance L refers to the distance from the foremost light receiving element 12 of the at least one light receiving element 12 that has been turned ON to the rearmost end of the detector 5. Since this distance L is unique to each light receiving element 12, it is obtained in advance in the design stage, is stored in a memory (not shown) of the gantry control circuit 17, is read out as appropriate, and is used to determine whether the condition is satisfied. As described above, since the proximity operation is not started until the condition in step S21 is satisfied from when the sensor 15 is switched from the ON state to the OFF state in step S17, the inching operation can be preferably prevented. Although the horizontal operation is performed during the engine in which the condition is not satisfied in step S21, the detector 5 is switched from the OFF state to the ON state by approaching the subject P to the predetermined distance during the horizontal operation. If it does, the process immediately returns to step S16 in accordance with the determination in step S22, and the separating operation is naturally started.

The present invention is not limited to the above-described embodiments, and can be implemented with various modifications without departing from the gist of the present invention. For example, in the above description, the detector 5 is set to 0
Although the scan was performed in a state fixed at the ° position, FIG.
When the rotating plate 3 is rotated in accordance with the movement of the detector 5 along the body axis O as shown in Fig. 5, when the detector 5 collects a SPECT image by a so-called helical scan that draws a spiral orbit. Can also be applied.

[0033]

According to the present invention, it is possible to detect radiation emitted from a radioisotope administered to a subject in a state in which the detector is brought closer to the subject, and further, the detector is finely separated from the subject. A jerky inching operation that repeats the operation can be prevented.

[Brief description of the drawings]

FIG. 1 is an external view of a scintillation camera according to one embodiment of the present invention.

FIG. 2 is a diagram showing an ultrasonic sensor applied to one embodiment of the present invention.

FIG. 3 is a diagram showing a reflection type optical sensor applied to one embodiment of the present invention.

FIG. 4 is a diagram showing an air mat sensor applied to one embodiment of the present invention.

FIG. 5 is a diagram showing a tension sensor applied to one embodiment of the present invention.

FIG. 6 is a diagram showing a facing optical sensor applied to one embodiment of the present invention.

FIG. 7 is a diagram showing another opposed-type optical sensor applied to one embodiment of the present invention.

FIG. 8 is a block diagram of a main part of one embodiment of the present invention.

FIG. 9 is a view for explaining a procedure for obtaining the position of the body axis of the subject.

FIG. 10 is a flowchart showing the flow of a scan operation according to one embodiment of the present invention.

FIG. 11 is a view for explaining an operation for preventing an inching operation included in the scan operation of FIG. 10;

FIG. 12 is a flowchart showing the flow of another scan operation according to an embodiment of the present invention.

FIG. 13 is a view for explaining a distance L under the conditions shown in FIG. 12;

FIG. 14 is a diagram showing a trajectory of a helical scan detector.

FIG. 15 is a diagram showing a scan trajectory of a detector by a conventional scintillation camera.

[Explanation of symbols]

 1 stand rail, 2 stand, 3 rotating plate, 4 arm, 5 detector.

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Claims (4)

(57) [Claims] A radiation detector for detecting radiation emitted from a radioisotope administered to the subject; rotating the radiation detector with respect to the subject or moving the radiation detector along a body axis of the subject A moving mechanism that moves the radiation detector away from or closer to the subject; a sensor that detects the distance of the radiation detector to the subject; and a radiation detector that detects the radiation to the subject. When the apparatus approaches a predetermined distance or less, the radiation detector starts the separating operation of the radiation detector with respect to the subject, and when the radiation detector exceeds the predetermined distance with respect to the object, the radiation detector Based on the output of the sensor, to stop the separation operation, when a predetermined time has elapsed from the stop of the separation operation, to start the approach operation of the radiation detector to the subject. Nuclear medicine diagnosis apparatus characterized by comprising a control circuit for controlling the serial away approximation mechanism. 2. A radiation detector for detecting radiation emitted from a radioisotope administered to a subject, the radiation detector rotating with respect to the subject or moving along a body axis of the subject. A moving mechanism that moves the radiation detector away from or closer to the subject; a sensor that detects the distance of the radiation detector to the subject; and a radiation detector that detects the radiation to the subject. When the apparatus approaches a predetermined distance or less, the radiation detector starts the separating operation of the radiation detector with respect to the subject, and when the radiation detector exceeds the predetermined distance with respect to the object, the radiation detector When the radiation detector is rotated by a specific distance with respect to the subject or moved by the moving mechanism along the body axis direction from the stop of the separating operation, the test is performed. The way to start the approaching operation of the radiation detector, nuclear medicine diagnostic apparatus characterized by comprising a control circuit for controlling said separating approximation mechanism based on the output of the sensor with respect. 3. The sensor has a plurality of light emitting elements, and a plurality of light receiving elements respectively corresponding to the light emitting elements,
The plurality of light-emitting elements and the plurality of light-receiving elements, the radiation detector so that a plurality of optical axes from the plurality of light-emitting elements to the plurality of light-receiving elements are substantially parallel to the detection surface of the radiation detector The nuclear medicine diagnostic apparatus according to claim 1, wherein the diagnostic apparatus is attached to a nuclear medicine diagnostic apparatus. 4. When the light from the light emitting element to the light receiving element is shut off, the sensor detects that the radiation detector has approached the subject less than the predetermined distance, and detects the light. 4. The nuclear medicine diagnostic apparatus according to claim 3, wherein the detector detects that the radiation detector has exceeded the predetermined distance with respect to the subject when the radiation is not blocked.