JPH08122438A - TCT / SPECT simultaneous acquisition system - Google Patents

Abstract

(57) [Abstract] [Purpose] Collecting emission data and transmission data while improving the image quality (resolution etc.) of the SPECT image and sufficiently securing an effective field of view when collecting transmission data. A TCT / SPECT simultaneous acquisition system for collecting transmission data based on radiation detected by a detector 5b and emission data based on radiation detected by a detector 5a simultaneously or substantially simultaneously. The radiation source 7B is arranged at a position opposite to the incidence surface of the detector 5b on which the radiation from the radiation source 7B is incident so that a desired effective field of view can be obtained, and the radiation source 7B is used as a detector. Support arm 7 fixedly supported on 5b
Equipped with A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to transmission data and SPECT for forming an attenuation coefficient distribution in a subject.
The present invention relates to a simultaneous TCT / SPECT acquisition system that collects emission data forming an image at the same time or substantially the same time.

[0002]

2. Description of the Related Art An γ-ray emitted from a radionuclide (radioisotope (hereinafter referred to as RI)) administered to a subject is detected by a gamma camera, and an image showing the RI distribution in the subject (hereinafter referred to as SPECT). SPEC to get the image)
There is a T device.

In this SPECT apparatus, the following two corrections are performed in order to quantify the SPECT image, that is, to make the SPECT image correspond to the RI distribution in the actual subject in a proportional relationship. That is, (1) "scattering correction" and (2) "attenuation correction".

(1) Scatterability correction means scattering of γ-rays inside a subject, and γ-rays inside a gamma camera (for example, inside a collimator, NaI scintillator, etc.) for a SPECT image obtained by a gamma camera. The method disclosed in Japanese Patent Laid-Open No. 5-87933 is known, for example, to effectively remove the .gamma.

On the other hand, (2) attenuation correction is as follows. That is, the γ-rays emitted from the RI administered into the body pass through the inside of the subject and are detected as emission data by the detector. At this time, the γ-rays are the bones and soft parts constituting the subject. The tissue is exponentially attenuated by an amount corresponding to the unique γ-ray absorption coefficient of each tissue.

The degree of this attenuation is non-uniform because it varies depending on the position and length of the path through which γ rays pass, and the RI distribution amount actually obtained lacks quantification.

In order to solve such a problem, an attenuation coefficient distribution (attenuation map) showing the degree of attenuation in the subject is measured, and the emission data is corrected (attenuation correction) with reference to the attenuation map data. ing.

As described above, in order to perform the attenuation correction, it is necessary to measure the attenuation coefficient distribution (attenuation map) in the subject. X-ray CT is one of the methods for measuring this attenuation map.

However, since the X-ray CT radiation source is white light (there is a wide range of energy), it is difficult to accurately obtain the attenuation coefficient distribution of γ-rays that are monochromatic light (the energy is different). Therefore, the absorption coefficient is also different). Further, the X-ray CT apparatus and the SPECT apparatus are separate apparatuses, and after the attenuation data is collected by the X-ray CT apparatus, the object is moved to the SPECT apparatus to collect the emission data. Since data and data cannot be collected at the same time, it is difficult to accurately align the position of the measurement target site of the subject.

Therefore, as a new method, a transmission (transmission type) CT (hereinafter, TCT; Transmis) for collecting transmission data by using a gamma camera for collecting emission data and obtaining an attenuation coefficient distribution of a subject.
sion computed tomography) device (this type of TCT device is also called TCT / SPECT acquisition system) has been devised. Regarding this TCT device, many patents, papers and academic conferences have been published so far.

・ Patent Number 5,055,687 Oct. 8,199
1 Ichihara (Toshiba) ・ Patent Number 5,075,554 Dec.24,1991 Yunker et
al. ・ Patent Number 5,289,008 Feb.22,1994 Jaszczak
et al. ・ R. Jaszczak et al "Fast Trasmission CT for Determ
ining Attenuation Maps a Collimated, Shuttered Lin
e Source and Fan Beam Collimation "Conference Recor
d of the 1992 IEEE Nucl.Sci.and Med.Img. ・ EPFicaro, et al "Simultaneous Transmission / Emiss
ion Tomography Using a Line Source with an Off-cent
er Fanbeam Collimator "1994 Society of Nucl.Med. When collecting transmission data and emission data using this TCT device (TCT / SPECT collection system), there are roughly two methods as follows: (1)" previously " A method of collecting transmission data in advance, then collecting emission data, and generating correction data based on the transmission data previously collected ”, (2)“ collecting transmission data and emission data at the same time, Method for generating correction data from data ".

In the method (1), since there is a time lag between the collection of transmission data and the collection of emission data, the movement of the subject and the internal (heart,
The environment for collecting the transmission data and the emission data differs due to the movement of the lungs, etc., and it may be difficult to obtain the true correction data.

Therefore, recently, the method (2) has been considered. As a system for simultaneously collecting the transmission data and the emission data of (2), a two-detector opposed type (two detectors are opposed to each other with the subject in between) TCT / SPECT simultaneous acquisition system as shown in FIG. There is.

In this system, a detector A for collecting emission data and a detector B for collecting transmission data are arranged on a pedestal (not shown) so as to face each other with the subject H in between. This pedestal is provided with a rotation mechanism (not shown) that integrally rotates the detectors A and B around the rotation center O. Further, a radiation source 50 for transmission data is arranged on the side surface of the detector A so that its γ-ray emitting side faces the detector B. Then, on the detection surface side of the detector B, a fan beam collimator whose focus is shifted from the rotation center O is attached.

According to this system, the γ-rays emitted from the RI previously administered to the subject are detected by the detectors A and B which rotate at each step angle, and are processed as a multi-directional emission data group. It

At the same time as the emission data is collected, the transmission data is also collected. That is, the γ-rays emitted from the radiation source 50 are transmitted through the subject H and then enter the detector B that rotates as described above via the fan beam collimator and are processed as transmission data.

[0017]

In the case of collecting emission data to obtain a SPECT image, a good image with high resolution can be obtained as the distance between the object and the detector is shorter due to the property of the collimator.

That is, as shown in FIG.
The beam profile of the γ-rays (emission data) emitted from the RI captured in the diagnostic region inside and captured by the detector A is better when the detector A is closer to the subject, and the resolution is higher. Has become. Therefore,
Due to the design, it was desirable that the detector A be arranged as close to the subject as possible.

On the other hand, when collecting the transmission data, the γ-ray emitted from the radiation source 50 is the subject H.
The wider the area (hereinafter, referred to as the effective field of view) that is transmitted through and enters the detector B, the more efficiently data can be collected. Therefore, as shown in FIG. 11, the radiation source 50 is separated from the subject H as much as possible, that is, the detector A is designed.
It was effective from the viewpoint of the effective visual field to arrange the lens as far away from the subject as possible.

That is, the detector A for effectively collecting the emission data and the transmission data
It was difficult to collect both under good conditions because the position conditions of were opposite. Even if the radiation source 50 is arranged away from the subject, the γ-rays emitted from the radiation source 50 are blocked by the detector A as shown in FIG. There was no

The present invention has been made in view of the above circumstances, and improves the image quality (resolution etc.) of a SPECT image,
It is possible to collect emission data and transmission data at the same time or almost at the same time while ensuring a sufficient effective field of view when collecting transmission data.
Its purpose is to provide a CT / SPECT simultaneous acquisition system.

[0022]

In order to achieve the above object, the TCT / SPECT collecting system according to claim 1 further comprises a first detecting means for detecting at least radiation emitted from a radiation source and transmitted through an object. Second detection means for detecting radiation emitted from a nuclide previously administered to the subject, the transmission data based on the radiation detected by the first detection means, and the second detection means. In the TCT / SPECT simultaneous acquisition system, which is designed to collect emission data based on the radiation detected by the above method at the same time or substantially at the same time, the first detection means includes a detector for injecting the radiation from the radiation source, The radiation source is arranged at a position facing the incident surface where a desired effective field of view is obtained with respect to the incident surface of the detector, and A source and a support means for fixing and supporting the detector.

Further, in particular, the TCT
In the SPECT simultaneous acquisition system, the support means is an arm mechanism having one end fixed to one side surface of the first detector and the other end provided with the radiation source.

Further, the TCT / SP according to claim 3
In the ECT simultaneous acquisition system, the radiation source is a radiation source, and a collimator having a large number of collimating holes is provided on the light-receiving surface side of the first detector, and the orientation of each of the holes is the line. It is formed so as to face the direction of the radiation source.

Furthermore, the TCT according to claim 4
In the SPECT simultaneous acquisition system, the detector of the first detecting means also serves as the detector of the second detecting means.

In particular, the TCT / SPE according to claim 5
In the CT simultaneous acquisition system, the second detection means includes a detector that detects radiation from the nuclide.

Further, in particular, the TCT
In the SPECT simultaneous acquisition system, the first and second detectors of the first and second detection means are diagonally opposed to each other via the central axis of the diagnostic opening of the gantry, and the second detector. The detector is placed so as to be out of the effective field of view from the radiation source.

Furthermore, the TCT / SP according to claim 7
In the ECT simultaneous acquisition system, the first and second detectors of the first and second detection means are arranged at positions facing each other in parallel to each other via the central axis of the diagnostic opening of the gantry.

[0029] Furthermore, the TCT according to claim 8
In the SPECT simultaneous acquisition system, a moving mechanism capable of moving the second detector in a direction opposite to the first detector within a preset range, and a second moving mechanism for moving the second detector when collecting the transmission data. In the direction away from the first detector, it is moved by a required distance so as to be out of the effective field of view, and when collecting the emission data, the second detector is required to approach the first detector. And a control means for controlling the movement so that the radiation source is moved by a distance of, and the radiation source is arranged outside the movement path of the second detector.

The TCT / SP according to claim 9
The ECT acquisition system comprises attenuation map data creating means for creating attenuation map data by reconstructing transmission data based on the radiation detected by the first detector, and the attenuation map data creating means comprises:
When the shape of the fan formed by the radiation source and the incident surface of the first detector is not an isosceles triangle, processing means for projecting the obtained projection data obliquely to process the shape of the fan into an isosceles triangle is provided. Have

On the other hand, in order to achieve the above-mentioned object, the invention according to claim 10
The simultaneous TCT / SPECT acquisition system described above detects a first detector that detects at least radiation emitted from a radiation source and transmitted through a subject, and a radiation emitted from a nuclide previously administered to the subject. A second detector, wherein the first and second detectors are arranged at positions facing each other in parallel to each other via the central axis of the diagnostic opening of the gantry, and by the first detector, TCT / SP for collecting transmission data based on the detected radiation and emission data based on the radiation detected by the second detector at the same time or substantially the same time
In the ECT simultaneous acquisition system, the radiation source is formed by a surface radiation source, and the radiation surface source is arranged at an end of a light receiving surface of the second detector and included in the emission data and the transmission data. And a scattered radiation removing means for removing scattered radiation.

[0032]

According to the present invention, the radiation emitted from the radiation source and transmitted through the subject is detected by at least the first detection means, and the radiation emitted from the nuclide previously administered to the subject is detected by the second radiation. Is detected by the detecting means. And
The transmission data based on the radiation detected by the first detection means and the emission data based on the radiation detected by the second detection means are collected simultaneously or substantially at the same time.

At this time, the first detection means is provided with a detector (first detector) for making the radiation from the radiation source incident, and the radiation source is fixedly supported by the supporting means on the first detector. In this state, the first detector is arranged at a position opposite to the incident surface where a desired effective field of view is obtained with respect to the incident surface.

That is, it is possible to sufficiently secure an effective visual field for detecting transmission data.

Further, for example, the first detector and the second detector of the second detector for detecting emission data are diagonally opposed to each other via the central axis of the diagnostic opening of the gantry. And the second detector is arranged at a position outside the effective field of view from the radiation source, the second detector will be covered regardless of the effective field of view to the first detector. It is possible to get close to the sample.

Further, for example, the first detector and the second detector
The detectors may be arranged at positions facing each other in parallel with each other via the central axis of the diagnostic opening of the gantry. Further, in this facing state, during transmission data collection, the second detector is moved by the moving mechanism in a direction away from the first detector by a required distance so as to be out of the effective field of view, and emission data is collected. At times,
The moving mechanism is controlled by the control means to move the second detector by a required distance in a direction approaching the first detector, and the radiation source is arranged outside the moving path of the second detector. Therefore, the second detector does not interfere with the effective field of view of the first detector during transmission data collection, and the second detector can be brought closer to the subject during emission data collection.

[0037]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) TCT / S according to the present embodiment
The PECT simultaneous acquisition system is equipped with a gamma camera for detection of transmission data and emission data. The structure of this gamma camera is shown in FIG. 1 (front view) and FIG. 2 (side view). Further, FIG. 3 shows a system configuration of a simultaneous TCT / SPECT acquisition system using this gamma camera.

The gamma camera 1 has a gantry 2, and the gantry 2 has a rotating frame 3 rotatably attached to the gantry 2 (in the α direction shown in FIG. 1). The pedestal 2
A diagnostic opening 3a is provided at the center of the rotating frame 3.

The rotating frame 3 is provided with a pair of detectors 5a and 5b via arms 4a and 4b in parallel with each other with the central axis of the opening 3a interposed therebetween. Of the pair of detectors 5a and 5b, the detector 5a is a detector for detecting γ-rays emitted from the inside of the subject, and the detector 5b is a detector for detecting γ-rays transmitted through the inside of the subject. is there.

The arm 4a supporting the detector 5a is extended along the direction (z direction) from the detector 5a to the detector 5b. In the arm 4a, a moving mechanism 6 in which, for example, a sprocket, a gear and the like are combined is provided, and the moving mechanism 6 moves the detector 5a along the extended arm 4a in the z direction and the opposite direction ( z1 direction)
It is configured to be movable.

In the initial state, the detector 5a is located at a predetermined distance from the center axis (referred to as the initial position), and the distance from the center axis of the opening 3a is the detector 5b.
It is located to be equidistant from.

The gamma camera 1 is provided with a radiation source radiation mechanism 7 which emits radiation (γ rays) for collecting transmission data. This radiation source radiation mechanism 7 has an arcuate support arm 7 composed of a tip portion 7a, an intermediate portion 7b, a base portion 7c, and connecting portions 7d1 to 7d2 for connecting them.
A and a radiation source 7B fixedly supported by a tip portion 7a of the support arm 7A, and a base portion 7 of the support arm 7A.
c is attached to one side of the detector 5b. Also,
The tip portion 7a, the intermediate portion 7b, and the base portion 7c of the support arm 7A
Are rotatable about the connecting portions 7d1 and 7d2, respectively. Normally, the connecting portions 7d1 and 7d are
2 is fixed.

The radiation source 7B is arranged so that its γ-ray emission direction is directed to the incident surface (also referred to as a detection surface) of the other detector 5b, and its effective field of view is sufficiently obtained. It is arranged at a position separated from the detector 5b by a required length. Further, the radiation source 7B is the z-axis of the detector 5a.
, And z1 so as not to interfere with the movement in the z1 direction.

That is, the radiation source 7B is arranged so that the positional relationship between the radiation source 7B and the detector B is constant by the support arm 7A.

It should be noted that the detector 5a can be moved to a position separated by a required length from the distance of the radiation source 7B from the detector 5b.

The gantry 1 is provided with a rotation drive unit 8 for rotating the rotary frame 3 and an angle sensor 9 for detecting the rotation angle of the rotary frame 3.

The detector 5a has a plate-shaped scintillator which absorbs the energy of the incident γ (gamma) rays and emits fluorescence at the incident point, and a large number of lead plates are provided on the incident surface side of this scintillator. A collimator provided with parallel holes (incident holes) is attached. A plurality of photomultiplier tubes (hereinafter referred to as “PMTs”) are arranged on the back side of the scintillator via a light guide.

The detector 5b is different from the detector 5a in the structure of the collimator. That is, the directions of the many incident holes of the collimator of the detector 5b are not parallel but directed to the γ-ray emitting point of the radiation source 7B. That is, the direction of the entrance hole of the collimator is the detector 5b.
Is regarded as the direction in which γ-rays are incident.

On the other hand, in the simultaneous TCT / SPECT acquisition system, as shown in FIG. 3, the position / energy calculation circuits 10a and 10b connected to the detectors 5a and 5b, respectively.
And γ-ray scattering component removal circuits 11a and 11b connected to the position / energy calculation circuits 10a and 10b.

The output of the γ-ray scattered component removing circuit 11a is connected to the corrected emission data generating circuit 12.
On the other hand, the output of the γ-ray correction component removal circuit 11b is connected to the attenuation map creation circuit 13. The output of the attenuation map creation circuit 13 is connected to the corrected emission data generation circuit 12.

An image memory 14, a D / A converter 15, and a display circuit 16 are sequentially provided on the output side of the corrected emission data generation circuit 12.

The support arm 7A of the detector 5a is provided with a detector movement control section 17 for controlling the movement timing and movement position of the detector 5a by controlling the movement mechanism 6 provided in the arm 7A. It is connected.

A detector rotation control unit 18 for controlling the rotation angle of the rotary frame 3 is connected to the rotary drive unit 8. The detector rotation control unit 18 is connected to the angle sensor 9 and finely adjusts the control angle based on the actual rotation angle of the rotating frame 3 detected by the angle sensor 9.

In the radiation source radiation mechanism 7, the tip 7a, the intermediate portion 7b, and the base 7c of the support arm 7A of the mechanism 7 are rotated, that is, the tip 7a, the intermediate portion 7b, and the base 7c. A radiation source support arm movement control unit 19 capable of controlling the incident direction of γ-rays on the detector 5b by controlling the rotational position is connected.

Furthermore, the TCT / SPECT simultaneous acquisition system is a controller 20 equipped with a computer circuit.
It has. This controller 20 includes a position / energy calculation circuit 10a, 10b, a γ-ray scattering component correction circuit 1
1a and 11b, attenuation map creation circuit 13, corrected emission data generation circuit 12, detector movement control unit 17, detector rotation control unit 18, and radiation source support arm movement control unit 1
9 can be individually controlled by sending control signals c1 to c9. Further, the controller 20 is connected to an input unit 21 that allows an operator to input necessary data to the controller 20.

In the detector 5a, when the γ-ray emitted from the RI in the subject H is incident upon collecting emission data, the incident point of the scintillator emits light. This light enters the plurality of PMTs through the light guide and is photoelectrically converted. Therefore, the PMT outputs a pulse signal proportional to the intensity of the incident light each time the γ-ray enters.

Further, in the detector 5B, when the transmission data is collected, the radiation is emitted from the radiation source 7B and the object H
When γ-rays that have passed through are incident, a pulse signal is output via the scintillator, the light guide, and the PMT as described above.

The pulse signals output from the detectors 5a and 5b are the position / energy calculation circuits 10a and 1a, respectively.
It is designed to be input to 0b.

Position / energy calculation circuits 10a, 10b
Has a preamplifier, a weighting resistor, an adder, etc. (not shown), and based on the pulse signal sent from the PMT,
The position and energy of the incident γ-ray is calculated for each incident of the ray, and after linearity correction and energy correction are added to the obtained position and energy, the energy signal of the digital value corresponding to those calculated values and The position signal is output to the γ-ray scattered component removing circuits 11a and 11b.

The γ-ray scattering component removing circuit 11a is disclosed in
-87933, that is, in the case of creating two-dimensional image data from the input energy signal and position signal, a plurality of energy windows (for example, three) are set for one photoelectric peak, and each of these energy windows is set. The scatter component correction coefficient is obtained by calculation between the images collected by the energy window. Then, the γ-ray scattering component is removed from the two-dimensional image data created using the scattering component correction coefficient. Then, the two-dimensional image data (emission data) from which the γ-ray scattering component is removed is output to the corrected emission data generation circuit 12.

Similarly, the γ-ray scattered component correction circuit 11b is
The two-dimensional image data from which the γ-ray scattering component has been removed is output to the attenuation map creating circuit 13.

The attenuation map creating circuit 13 receives the input 2
Image reconstruction processing known in an X-ray CT apparatus is performed on the three-dimensional image data to generate reconstructed image data (γ-ray absorption coefficient distribution data, in other words, attenuation coefficient distribution data (attenuation map data).

In this configuration, the radiation source 7B is the detector 5
It is not located on the center line of the detection surface of b (in the case of the X-ray CT apparatus, the X-ray tube is at this position). Therefore, the shape of the γ-ray (fan beam) emitted from the radiation source 7B and detected by the detector 5B is not an isosceles triangle.

Therefore, the profile correction circuit 13a performs the image reconstruction process after performing either one of the following two arithmetic processes. (1) Reconstruction processing of a tomographic image is performed after performing arithmetic processing for rearranging fan beams that are not isosceles triangles in a parallel state.
(2) The fan beam data thus obtained is subjected to data processing for obliquely projecting it by arithmetic processing to form fan beam data of an isosceles triangle, and then reconstruction processing is performed (see FIG. 4).

Then, the attenuation map producing circuit 13 outputs the obtained attenuation map data to the corrected emission data producing circuit 12.

The corrected emission data generation circuit 12 is
Equipped with an arithmetic circuit equipped with a memory, a computer, etc., based on the input emission data and attenuation map data, for example, the correction emission data is generated using a correction algorithm such as the Sorenson method or Chang method. That is, the SPECT image data is output to the image memory 14.

SPECT sent to the image memory 14
The image data is sent to the analog S through the D / A converter 15.
After being converted into a PECT image, it is displayed on the display of the display circuit 16.

Next, the overall operation will be described centering on the simultaneous operation of collecting emission data and transmission data.

First, RI for SPECT (for example, Tl-20
Subject H placed on the bed of the bed after the injection of 1)
To the required position in the diagnostic opening 3a (the facing detector 5
Insert it at the position where the diagnostic site comes between a and 5b) (Fig. 2
reference). Then, the rotation step angle θ (for example, 3 to 10 °) of the rotation frame 3a is input from the input unit 21, and the data for determining the rotation trajectory of the detector 5a is input. For example, when performing an elliptical orbit, ellipse data (focal point, major axis, minor axis, etc.) is input. Controller 20
Calculates the proximity position of the detector 5a to the subject H for each step angle θ from the step angle θ and the trajectory data (ellipse) of the detector 5a, and stores it in the internal memory.

The data for determining the rotational orbit may be, for example, a circular orbit, and a locus (body surface data) corresponding to the silhouette of the subject is preliminarily input to the detector 5a.
It is also possible to set a close position along the body surface of the subject H.

The step angle θ and the proximity position data are
It is stored in the internal memory of the controller 20.

Then, the operator operates the input unit 21 to send a pseudo simultaneous acquisition command of emission data and transmission data to the controller 20.

Upon receipt of the simultaneous collection command, the controller 20 performs the processing shown in FIG. That is, the controller 20 first reads the step angle θ stored in the memory (step 101), and further reads the proximity position data (step 102).

Next, the controller 20 sends a command signal C7 (1) for moving the detector 5a in the initial state to the proximity position to the detector moving section 17 (step 103).
The detector movement control unit 17 receives the command C7 (1) and controls the movement mechanism 6. As a result, the detector 5a in the initial position moves in the z1 direction and reaches the proximity position (see FIG. 2).

As a result, the γ-ray emitted from the subject H is detected by the detector 5a. Controller 20
Sends command signals C1 and C3 (emission data collection command) to the position / energy calculation circuit 11a and the γ-ray scattered component correction circuit 11b, respectively, to collect emission data (step 104).

After the data has been collected for a certain period of time, the processing of the controller 20 proceeds to step 105, where a command signal for moving the detector 5a in the near position to a position (far position) sufficiently far from the subject H is detected. Send C7 (2). As a result, the detector 5a in the proximity position moves in the z direction,
Reach a distant position (see Figure 2).

On the other hand, γ-rays are emitted toward the subject H from the radiation source 7B.

The emitted γ-rays are detected by the detector 5b after passing through the subject H. The controller 20 sends command signals C2 and C4 (transmission data collection command) to the position / energy calculation circuit 10b and the γ-ray scattering component correction circuit 11b, respectively, to collect transmission data (step 106).

After the data is collected for a fixed time, the processing of the controller 20 proceeds to step 107, where the command signal C8 for rotating the rotating frame 3 by the step angle θ is provided.
To the detector rotation control unit 18. Detector rotation control unit 18
Then, the rotation drive unit 8 is controlled in response to the command C8.
As a result, the rotating frame 3 rotates by the step angle θ.

After that, the controller 20 carries out the above-mentioned steps 101 to 107. In addition,
Since the radiation source 7B is fixedly supported by the detector 5b via the support arm 7A, even if the rotation frame 3 rotates, that is, the detectors 5a and 5b rotate, the radiation source 5
b and the detector 5b rotate integrally with each other in a state where their positional relationship does not change. Therefore, the transmission data can be detected regardless of the rotation of the rotating frame 3.

By the processing of steps 101 to 107, emission data and transmission data in a state where the rotary frame 3 is rotated by the step angle θ are collected.

Then, the controller 20 determines whether or not the total sum θsum of the rotated angles of the rotary frame 3 exceeds 360 ° (step 108). Since the rotation angle of the rotating frame 3 is only the step angle θ at this time, the result of this determination is NO, and the controller 20 returns to the processing of step 101 and repeats the processing of steps 101 to 108 described above. . Therefore, emission data and transmission data are collected for each step angle θ, that is, from multiple directions. This emission data is sent to the corrected emission data generation circuit 12, and the transmission data is sent to the corrected emission data generation circuit 12 as attenuation map data via the attenuation map creation circuit 13.

After collecting data in this way,
When the total sum θsum of the rotation angles of the rotating frame 3 exceeds 360 angles, that is, when the rotating frame 3 makes one rotation, the determination in step 108 becomes YES, and the processing of the controller 20 proceeds to step 109.

In step 109, the controller 2
0 sends a command (command signal C6) for generating corrected emission data to the corrected emission data generation circuit 12,
The process ends.

The corrected emission data generation circuit 12 generates corrected emission data based on the input emission data and attenuation map data.
This corrected emission data (SPECT image data)
Is sent to the display circuit 16 via the image memory 14 and the D / A converter 15. As a result, a SPECT image that has been subjected to scattered radiation correction and attenuation correction is displayed.

As described above, according to this embodiment, when collecting emission data, the detector 5a is moved to a predetermined proximity position, and when collecting transmission data, The detector 5b can be moved to an appropriate position sufficiently separated from the subject H. Therefore, even if the radiation source 7B is arranged at a position where a sufficient effective field of view is obtained in advance, the detector 5a does not block the effective field of view, and transmission data can be efficiently collected.

Incidentally, step 105 of the controller 20
Command signal C9 is sent to the radiation source support arm movement control section 19 during the processing of step 106 and the processing of step 106,
By rotating the tip portion 7a, the intermediate portion 7b, and the base portion 7c of A, for example, the position where the γ-ray emitting surface of the radiation source 7B and the γ-ray detecting surface of the detector 5b are substantially parallel (the hole of the collimator Can also be moved to (depending on the position of the radiation source 7B), and the effective field of view can be further increased.

(Second Embodiment) FIG. 6 shows a front view of the gamma camera 22 in this embodiment. That is, according to the present embodiment, the detector 5b for detecting transmission data is arranged at a position distant from the central axis of the opening 3a by a required length, while the radiation source 7B is replaced by the γ of the radiation source 7B. It is arranged at a position where the radiation direction is directed to the detection surface of the detector 5b and a position where the effective field of view to the detector 5b is good.

The detector 23 for detecting emission data is replaced with the detector 5b for detecting transmission data.
And the detector 2 at positions that do not face each other but diagonally face each other through the central axis of the diagnostic opening 3a of the gantry 3.
3 is arranged at a position outside the effective field of view from the radiation source 7B. Then, the detector 23 includes the arm 4a.
The moving mechanism 6a having substantially the same structure as the first embodiment can move in the direction toward the central axis of the opening 3a and the opposite direction. The outputs of the detector 23 and the detector 5b are connected to a circuit group having substantially the same circuit configuration as that shown in FIG. The rest of the configuration is substantially the same as that of the first embodiment, and its explanation is omitted.

With such a configuration, even if the detector 23 for collecting emission data is moved to the above-mentioned proximity position with respect to the subject 1H at the time of data collection, the detector 23 will be separated from the radiation source 7B. Since the field of view to the detector 5b is not obstructed, a sufficient effective field of view can be secured.

Therefore, both emission data and transmission data can be simultaneously collected under mutually favorable conditions.

(Third Embodiment) FIG. 7 shows a front view of the gamma camera 24 in this embodiment. In this embodiment, a single detector 25 collects emission data and transmission data. That is, the detector 25 is arranged at a position away from the central axis of the opening 3a by a required length, while the radiation source 7b is oriented so that the γ-ray radiation direction of the radiation source 7b is toward the detection surface of the detector 5b. It is arranged at such a position and has a good effective field of view with respect to the detector 25.

Further, the detector 25 is movable in the direction toward the central axis of the opening 3a and in the opposite direction by the moving mechanism 6b of the support arm 4b, which is constructed in substantially the same manner as in the first embodiment. The output of the detector 25 is connected to a circuit group substantially equivalent to the circuit configuration shown in FIG. The rest of the configuration is substantially the same as that of the first embodiment, and its explanation is omitted.

With this configuration, the detector 25 can be moved to the above-described proximity position to the subject H at the time of collecting emission data, and can be returned to the normal position at the time of collecting transmission data. . That is, at the time of collecting emission data, the detector 25 can be moved to a close position to collect data, and at the time of collecting transmission data, the data can be collected in a state in which a sufficient effective field of view from the radiation source 7B to the detector 25 is secured. It can be collected.

Therefore, both emission data and transmission data can be simultaneously collected under favorable conditions.

(Fourth Embodiment) FIG. 8 shows a front view of the gamma camera 26 in the present embodiment. In this embodiment, the opening 3
A pair of detectors 27a and 27b are provided so as to face each other in parallel with the central axis of a therebetween. This detector 2
A surface radiation source 28 is provided in a part of the detector 27a on the incident surface side of the detectors 7a and 27b. Also, the detector 27a
Is for emission data collection, and the detector 27b is
Both emission data and transmission data can be collected. Further, the detectors 27a and 27b are movable in the direction toward the central axis of the opening 3a and the opposite direction by the moving mechanisms 6a and 6b of the arms 4a and 4b, respectively.

The system configuration of this embodiment is substantially the same as that of the first embodiment, except that the output of the detector 27b is connected to the position / energy calculation circuit 10a and the position / energy calculation circuit 10b. It is that. That is, in the detector 27b, the pulse signal based on the γ-ray corresponding to the emission data is converted into the position / energy calculation circuit 1
Output to 0a and correspond to transmission data γ
Position / energy calculation circuit 10 for pulse signals based on lines
It is designed to output to b.

According to this embodiment, the surface radiation source 28 is used as the radiation source.
Is provided on a part of the detection surface side of the detector 27a,
A sufficient effective field of view can be obtained regardless of the position of the detector 27a.

At this time, (1) the effective field of view of the detector 27a is narrowed, and (2) since the surface radiation source 28 is used, the mixing of scattered rays increases, but (1) Even in the worst case, the problem of can be avoided by collecting the emission data and the transmission data by the detector 27b, and the problem of (2) can also be solved.
This can be avoided by removing the scattered rays increased in 1a and 11b.

[0101]

As described above, according to the present invention, regardless of the position of the detector for detecting emission data,
Since a sufficient effective field of view to the transmission data detector is obtained, transmission data can be collected efficiently.

Further, since the detector for detecting emission data is configured to be moved to a position outside the effective field of view of the detector for detecting transmission data or a position outside the detector for collecting emission data,
It is possible to bring the detector for emission data detection close to a desired position with respect to the subject while maintaining a state in which the effective visual field is sufficiently obtained. Therefore, emission data can also be collected efficiently.

As a result, the image quality (resolution or the like) of the SPECT image generated by the emission data and the transmission data can be improved.

[Brief description of drawings]

FIG. 1 is a TCT / SPECT according to a first embodiment of the present invention.
The front view of the gamma camera of a simultaneous acquisition system.

FIG. 2 shows a TCT / SPECT according to the first embodiment of the present invention.
The side view of the gamma camera of a simultaneous acquisition system.

FIG. 3 shows a TCT / SPECT according to the first embodiment of the present invention.
System configuration diagram of the simultaneous collection system.

FIG. 4 is a diagram conceptually showing a process of changing a fan beam profile.

FIG. 5 is a schematic flowchart showing an example of processing of the controller in the first embodiment.

FIG. 6 is a TCT / SPECT according to a second embodiment of the present invention.
The front view of the gamma camera of a simultaneous acquisition system.

FIG. 7 shows a TCT / SPECT according to a third embodiment of the present invention.
The front view of the gamma camera of a simultaneous acquisition system.

FIG. 8 is a TCT / SPECT according to a fourth embodiment of the present invention.
The front view of the gamma camera of a simultaneous acquisition system.

FIG. 9 is a diagram showing a schematic configuration of a conventional two-detector type TCT / SPECT simultaneous acquisition system.

FIG. 10 is a diagram showing changes in a beam profile with respect to a position of a detector for collecting emission data from a subject.

FIG. 11 is a diagram showing a change in effective visual field with respect to a distance from a subject of a detector for collecting transmission data.

[Explanation of symbols]

 1 gamma camera 2 mount 3 rotating frame 3a diagnostic opening 4a arm 4b arm 5a detector 5b detector 6 moving mechanism 7 radiation source emitting mechanism 7a tip part 7b middle part 7c base part 7d1 connecting part 7d2 connecting part 7A wire supporting arm Radiation source 8 Rotation drive unit 9 Angle sensor 10a, 10b Position / energy calculation circuit 11a, 11b Gamma ray scattering component correction circuit 12 Corrected emission data generation circuit 13 Attenuation map generation circuit 13a Profile correction circuit 14 Image memory 15 D / A converter 16 display circuit 17 detector movement control unit 18 detector rotation control unit 19 radiation source support arm movement control unit 20 controller 21 input unit 22 gamma camera 23 detector 24 gamma camera 25 detector 26 gamma camera 27a detector 27b detector 28 Source

Claims (10)

[Claims] 1. A first detection means for detecting at least radiation emitted from a radiation source and transmitted through a subject, and a second detection means for detecting radiation emitted from a nuclide previously administered to the subject. And TCT / SPECT simultaneous acquisition of transmission data based on the radiation detected by the first detection means and emission data based on the radiation detected by the second detection means simultaneously or substantially simultaneously. In the collection system, the first detection means includes a detector that causes radiation from the radiation source to enter, and the first detection means is provided at a position opposite to the incidence surface of the detector where a desired effective field of view is obtained. A TCT, characterized in that a radiation source is arranged and a supporting means for fixing and supporting the radiation source to the detector is provided.
SPECT simultaneous acquisition system. 2. The simultaneous TCT / SPECT acquisition system according to claim 1, wherein the support means is an arm mechanism having one end fixed to one side surface of the first detector and the other end provided with the radiation source. . 3. The radiation source is a radiation source, and a collimator having a large number of collimating holes is provided on the light-receiving surface side of the first detector, and the orientations of the respective holes are the radiation lines. The TC according to claim 1, wherein the TC is formed so as to face the source.
T ・ SPECT simultaneous acquisition system. 4. The simultaneous TCT / SPECT acquisition system according to claim 1, wherein the detector of the first detecting means also serves as the detector of the second detecting means. 5. The TCT according to claim 1, wherein the second detecting means includes a detector for detecting radiation from the nuclide.
・ SPECT simultaneous collection system. 6. The first and second detectors of the first and second detecting means are diagonally opposed to each other via a central axis of a diagnostic opening of a gantry, and the second detector is provided. 6. The simultaneous TCT / SPECT acquisition system according to claim 5, wherein the detector is arranged at a position outside the effective field of view from the radiation source. 7. The first and second detectors of the first and second detection means are arranged at positions facing each other in parallel with each other through the central axis of the diagnostic opening of the gantry. TC
T ・ SPECT simultaneous acquisition system. 8. A moving mechanism capable of moving the second detector in a direction opposite to the first detector within a preset range, and the second detector when the transmission data is collected. In the direction away from the first detector,
And a control means for moving the second detector by a required distance so as to be out of the effective field of view, and for moving the second detector by a required distance in a direction approaching the first detector when collecting the emission data. 8. The simultaneous TCT / SPECT acquisition system according to claim 7, further comprising: a radiation source disposed outside the movement path of the second detector. 9. An attenuation map data creating means for creating attenuation map data by reconstructing transmission data based on the radiation detected by the first detector, the attenuation map data creating means comprising: When the shape of the fan formed by the source and the entrance surface of the first detector is not an isosceles triangle, the projection data obtained is obliquely projected to process the shape of the fan into an isosceles triangle. The simultaneous TCT / SPECT acquisition system according to claim 8. 10. A first detector for detecting at least radiation emitted from a radiation source and transmitted through a subject, and a second detector for detecting radiation emitted from a nuclide previously administered to the subject. And arranging the first and second detectors at positions facing each other in parallel with each other through the central axis of the diagnostic opening of the gantry, and adding radiation to the radiation detected by the first detector. In the TCT / SPECT simultaneous acquisition system, wherein the transmission data based on the radiation and the emission data based on the radiation detected by the second detector are collected simultaneously or substantially at the same time, the radiation source is formed by a surface radiation source, A surface radiation source is arranged at the end of the light receiving surface of the second detector, and scattered rays contained in the emission data and the transmission data are removed. T equipped with means for removing scattered radiation
CT / SPECT simultaneous acquisition system.