JP2003232854A - Device for nuclear medicine diagnosis, image processor, and method for image reconstruction - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for nuclear medicine diagnosis, an image processor, and a method for image reconstruction, capable of reducing the number of times of interpolating calculations by conducting direct-method reconstruction and capable of providing diagnostic images with high spacial resolution. <P>SOLUTION: Fan beam data and parallel beam data corresponding to 180 deg. or 360 deg., for example, are collected and image reconstruction is performed by direct-method back projection of the fan beam data as to a region where fan beam data exist. Meanwhile, as to a region where no fan beam exists, image reconstruction is performed by back projection based on the parallel beam data. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a nuclear medicine diagnostic device,
The present invention relates to an image processing device and an image reconstruction method.

[0002]

2. Description of the Related Art A nuclear medicine image is a radioisotope (R
I: gamma rays emitted from the RI are measured from outside the body by utilizing the property that a drug labeled with I: Radio-Isotope) is selectively taken up by specific tissues or organs in the living body, and its dose distribution is imaged. It is used to capture the functions of internal organs. In this nuclear medicine image, a planar image taken with the detector fixed and an ECT (Emission Computation) taken with the detector moved around the human body
a single photon emission computer tomography (single tomography) image as a typical device for photographing the latter ECT image.
e Photon Emission Compute
d Tomography: Hereinafter referred to as "SPECT". There is a device.

The SPECT apparatus injects a radioisotope into a subject such as a patient, detects γ-rays emitted from the body, and measures RI distribution by this, thereby measuring lesions in the body, blood flow, It is possible to display a functional distribution image such as fatty acid metabolism.

In these nuclear medicine diagnostic apparatuses, a fan beam collimator and a parallel beam collimator are usually used in order to collect γ-rays emitted from a subject efficiently. For example, when the diagnosis site is small like a head, data is collected using a fan beam collimator so that the head does not protrude from the effective visual field. Further, when the diagnosis site is the heart or the like, the fan beam collimator and the parallel beam collimator may be simultaneously used to collect data. Hereinafter, the projection data collected by the fan beam collimator will be referred to as “fan beam data”, and the projection data collected by the parallel beam collimator will be referred to as “parallel beam data”. Further, the conversion from fan beam data to parallel beam data is called "fan-parallel conversion". The collected fan beam data is converted into parallel beam data by fan-parallel conversion and used as raw data.

By the way, generally, the detection using the fan beam collimator has higher sensitivity and higher resolution in the depth direction than the case of using the parallel beam collimator. On the other hand, the effective field of view becomes narrower than that of the parallel beam collimator, which may cause truncation in which data exists outside the effective field of view. This truncation causes an artifact and is not preferable for image diagnosis. The conventional nuclear medicine diagnostic apparatus collects data for such truncation by using the fan beam collimator and the parallel beam collimator at the same time, and uses the data collected by the parallel beam collimator as shown in FIG. The problem is solved by supplementing the part outside the effective field of view and creating synthesized parallel beam data.

Since there is a difference between the count when the fan-beam data is fan-parallel converted and the count of the parallel beam data, if the fan-parallel converted data and the parallel beam data are simply combined, the data will be discontinuous. Part occurs. To correct this discontinuity,
In the above prescription, the average value of the area where both fan-parallel converted data and parallel beam data exist is taken, and the parallel beam data is multiplied by the ratio of the average values.

Parallel beam back projection is applied to the continuous parallel data thus obtained to reconstruct it as volume data. This makes it possible to obtain a reconstructed image having a resolution better than that of the parallel beam collimator and having no fan beam truncation error.

However, the above-mentioned conventional nuclear medicine diagnostic apparatus is configured to execute interpolation calculation in the process of fan-parallel conversion and parallel beam back projection. Therefore, the reduction of the resolution becomes large due to the interpolation processing performed twice in total.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to provide a diagnostic image with high spatial resolution by reducing the number of interpolation calculations by performing direct method reconstruction. An object of the present invention is to provide a medical diagnostic device, an image processing device, and an image reconstruction method.

[0010]

The present invention takes the following means in order to achieve the above object.

According to a first aspect of the present invention, there is provided a first collimator for collimating the radiation emitted from the radioisotope administered to the subject into a fan beam shape, and first detecting means for detecting the incident radiation. A second collimator for collimating the radiation emitted from the subject into a parallel beam shape, and second detecting means for detecting the incident radiation, and a fan by rotating the subject about a predetermined angle. Obtaining beam data and parallel beam data, in the nuclear medicine diagnostic device for reconstructing the concentration distribution of the radioisotope, for the region where the fan beam data exists, the direct method back projection of the fan beam data is performed, and For areas where fan beam data does not exist, the backprojection of the parallel beam data is performed. Deployment a nuclear medicine diagnosis apparatus characterized by comprising an image reconstruction means for performing.

According to a third aspect of the present invention, there is provided a first collimator for collimating the radiation emitted from the radioisotope administered to the subject into a fan beam shape, and first detecting means for detecting the incident radiation. And a second collimator for collimating the radiation emitted from the subject into a parallel beam shape, and second detecting means for detecting the incident radiation, by rotating the subject about a predetermined angle. Data for converting the parallel beam data into fan beam data to obtain pseudo fan beam data in a nuclear medicine diagnostic apparatus that acquires the fan beam data and the parallel beam data of 1 and reconstructs the concentration distribution of the radioisotope. The conversion unit and an area of the pseudo fan beam data corresponding to the fan beam data are By replacing the chromatography data, and synthetic data generating means for generating a combined data, a nuclear medicine diagnosis apparatus characterized by comprising an image reconstruction means for performing direct method backprojection of the combined data.

According to a sixth aspect of the present invention, fan beam data acquired based on a fan beam obtained by collimating the radiation emitted from the radioisotope inside the object into a fan beam shape, and the object is emitted from the subject. An image processing apparatus for reconstructing a concentration distribution of a radioisotope from parallel data acquired based on parallel beams obtained by collimating radiation into a parallel beam shape, wherein the fan beam data is present in the fan. The image processing apparatus is characterized by comprising an image reconstructing unit for performing direct method back projection of beam data and performing back projection of the parallel beam data for an area where the fan beam data does not exist.

According to a seventh aspect of the present invention, fan beam data acquired based on a fan beam obtained by collimating radiation emitted from a radioisotope inside a target object into a fan beam shape, and the object is emitted from the subject. An image processing device for reconstructing a concentration distribution of a radioisotope from parallel data acquired based on parallel beams obtained by collimating radiation into parallel beam shapes, by converting the parallel beam data into fan beam data. Data conversion means for acquiring pseudo fan beam data,
Of the pseudo fan beam data, a region corresponding to the fan beam data is replaced with the fan beam data to generate a synthetic data, and an image reconstruction for performing the direct method back projection of the synthetic data. And an image processing apparatus.

According to an eighth aspect of the present invention, fan beam data acquired based on a fan beam obtained by collimating radiation emitted from a radioisotope inside a target object into a fan beam shape, and the object is emitted from the subject. An image processing method for reconstructing a concentration distribution of a radioisotope from parallel data acquired based on a parallel beam obtained by collimating radiation into a parallel beam shape, wherein the fan beam data is included in an area corresponding to the fan. The image processing method is characterized in that direct method back projection of beam data is performed, and back projection of the parallel beam data is performed in an area where the fan beam data does not exist.

According to a ninth aspect of the present invention, fan beam data acquired based on a fan beam obtained by collimating the radiation emitted from the radioisotope inside the object into a fan beam shape, and the object is emitted from the subject. From parallel data acquired based on parallel beams obtained by collimating radiation into parallel beam shapes, an image processing method for reconstructing the concentration distribution of the radioisotope, converting the parallel beam data to fan beam data. Pseudo fan beam data is generated, and a region corresponding to the fan beam data in the pseudo fan beam data is replaced with the fan beam data to generate synthetic data, and the direct method back projection of the synthetic data is performed. An image processing method characterized by the above.

According to such a configuration, the number of interpolation calculations is reduced by performing the direct method reconstruction, and a nuclear medicine diagnostic apparatus, an image processing apparatus and an image reconstruction method capable of providing a diagnostic image with high spatial resolution. Can be realized.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In the following description, constituent elements having substantially the same functions and configurations are designated by the same reference numerals, and redundant description will be given only when necessary.

FIG. 1 is a nuclear medicine diagnostic apparatus 1 according to this embodiment.
0 configuration is shown. As shown in the figure, the nuclear medicine diagnostic device 10 includes two-dimensional detectors 11A and 11B, a position calculation circuit 12, a bed 13, a rotary frame 14, a bed movement / shift / up / down control unit 15, and a general rotation control unit 16. Detector movement / tilt / shift control unit 17, collection controller 18, collection image memory 22, data processing circuit 23, display circuit 24, controller 25, movement / tilt / shift mechanism 2
6. The image memory 27 is provided.

The two-dimensional detectors 11A and 11B are, for example, N
Detector with photocell attached to aI scintillator, or Cd
It is a semiconductor detector in which a semiconductor element formed by bonding a bias electrode and a signal electrode to a compound semiconductor piece such as Te (cadmium telluride) is two-dimensionally arranged. One of the two-dimensional detectors 11A and 11B is provided with γ from the subject P.
The two-dimensional detectors 11A and 11B have a fan-beam collimator that shapes a line into a fan-shaped beam, and the other two-dimensional detectors 11A and 11B have a parallel-beam collimator that shapes a γ-ray from the subject P into a parallel-beam. Hereinafter, the two-dimensional detector 11A has a fan beam collimator, and the two-dimensional detector 11B has a parallel beam collimator. In the following description, the projection data collected by the fan beam collimator will be referred to as "fan beam data", and the projection data collected by the parallel beam collimator will be referred to as "parallel beam data".

FIG. 2 shows an example of a configuration in which radiation is collected from the heart of a subject by using a two-dimensional detector 11A having a fan beam collimator and a two-dimensional detector 11B having a parallel beam collimator. It is the figure shown.
In the case of SPECT imaging, two-dimensional detectors 11A, 11
B is a predetermined angle (for example, 180 degrees or 36 degrees) around the subject.
Rotate by 0 degree) and collect projection data for that angle.

In the present embodiment, the two-dimensional detector 11
Nuclear medicine diagnostic device 10 having two detectors A and 11B
However, the technical idea of the present invention is also applicable to a nuclear medicine diagnostic apparatus having two or more, for example, three detectors. In this case, for example, two of the three detectors each have a fan beam collimator, and the average of both fan beam data is used to further improve the sensitivity.

The position calculation circuit 12 includes a two-dimensional detector 11
Based on the outputs of A and 11B, every time a gamma ray is incident, a position signal indicating the incident position and angle and an energy signal indicating the energy are output.

The bed 13 has a structure and a drive source necessary for moving and shifting along the rotation axis in a state where the subject P is placed, and a bed and a drive source substantially in relation to the rotation axis when the subject P is placed. It has the structure and drive source necessary to shift along orthogonal orthogonal axes.

The rotating frame 14 supports a moving / tilting / shifting mechanism 26, and has a structure and a drive source for rotating the two-dimensional detectors 11A and 11B around a rotation axis substantially parallel to the body axis of the subject P. Have

The bed movement / shift / up / down control unit 15 controls the position of the bed 13 in association with the movement of the detectors 11A and 11B at a predetermined timing.

The overall rotation control unit 16 includes a two-dimensional detector 11
In order to rotate A and 11B around a rotation axis substantially parallel to the body axis of the subject P, the rotating frame 14 is controlled.

The detector movement / tilt / shift control section 17 is
The movement / tilt / shift mechanism 26 is controlled to move in a predetermined arrangement, for example, the detectors 11A and 11B are rotated around the subject.

The collection controller 18 controls the collection of the electric pulse signals from the detectors 11A and 11B accompanying the incidence of γ-rays and the position signal from the position detection circuit 12. Further, the collection controller 18 uses the two-dimensional detector 11
When photographing A and 11B in a tilted state, the start of the counting period is controlled for each semiconductor element. Here, shooting means
This means an operation of counting gamma rays from a radioisotope administered to a subject as the number of photons.

The collection memory 22 counts gamma rays as the number of photons for each incident position, angle and energy based on the position signal and the energy signal.

The data processing circuit 23 includes the image memory 2
Based on the counting result held in 2, the sinogram data is created, various corrections are made, and the ECT imaging is performed by reconstructing the concentration distribution (tomographic image) of the radioisotope in the cross section of the subject. The reconstruction processing by the data processing circuit 23 will be described later in detail by taking the data processing at the time of SPECT imaging as an example. The planar image and the tomographic image are sent to the display circuit 24 and displayed, for example, in gray scale.

The controller 25 is provided for centrally controlling the movement of these devices as a whole.

The movement / tilt / shift mechanism 26 supports the two-dimensional detectors 11 and 12, and moves the detectors under the control of the detector movement / tilt / shift control section 17. Also,
The moving / tilting / shifting mechanism 26 is a two-dimensional detector 11A,
Structure and drive source required to move and shift 11B along the rotation axis, and structure required to shift two-dimensional detectors 11A and 11B along an orthogonal axis substantially orthogonal to the rotation axis, and Drive source and two-dimensional detector 11A,
11B has a structure and a drive source necessary for inclining 11B with respect to the rotation axis.

The image memory 27 includes the data processing circuit 2
3. Store the image reconstructed by 3. These images are displayed on the display circuit 24 as images of predetermined tomographic images.

FIG. 3 shows a series of operations from imaging, data processing, and display of the nuclear medicine diagnostic apparatus 10 having the above configuration.
It will be described with reference to FIGS.

FIG. 3 is a flow chart showing a processing procedure executed by the nuclear medicine diagnostic apparatus 10 until SPECT imaging, data processing and display. In FIG. 3, first, the detectors 11A and 11B are rotated around a subject by a predetermined angle (for example, 180 ° or 360 °), and fan beam data and parallel beam data for the predetermined angle are collected ( Steps S1 and S1 '). Each collected data is stored in the collection memory 22.

Subsequently, condition setting for each process in the subsequent stage, for example, sensitivity correction coefficient setting, coefficient setting for uniformity correction, and the like are performed (step S2).

Next, the collected fan beam data and parallel beam data are expanded in the detection direction and the projection direction to generate sinogram data (step S3).

Next, the fan beam data is subjected to sensitivity correction by the opening angle of the fan beam (step S).
4). Gamma radiation from the subject is isotropic. But,
The value of γ-rays emitted by the detector 11A is high at the center of the detector due to the characteristics of the fan beam collimator, and becomes lower toward the outside. In this step, the sensitivity is corrected by multiplying the variation in the detected value caused by the angle of the fan beam by, for example, a preset correction coefficient.

Next, in order to correct the difference in sensitivity between the parallel beam data and the fan beam data, the parallel beam data is normalized (step S5). Specifically, the sensitivity correction is performed by multiplying the parallel data by a constant that corrects the difference in sensitivity between the fan beam and the parallel data. This constant is determined as follows.

FIG. 4 is a diagram for explaining a method of determining a correction constant to be added to the parallel data in order to correct the difference in sensitivity with the parallel beam data. As shown in FIG. 4, as the correction constant, the ROI is set at the same position in the reconstructed image of the fan beam data without truncation and the reconstructed image of the parallel data, and the count average value in the ROI is made the same. Predetermined as a constant. At this time, the reconstructed image of the fan beam data used for determining the constant is preferably subjected to the sensitivity correction based on the fan beam opening angle executed in step S4 in order to make the sensitivity correction more appropriate. . The determined constants are tabulated and stored in the memory.

The sensitivity correction in step S5 is as follows.
The method is not limited to the method using the correction coefficient, and any method may be used as long as the same purpose can be achieved. For example,
As another method, there is a method of obtaining a function of a sensitivity distribution curve of fan beam data and performing sensitivity correction of parallel data according to the function.

Next, the fan beam data and the parallel data are multiplied by a one-dimensional convolution function (reconstruction function) to perform convolution (step S6).

Next, reconstruction is performed using the fan beam data and parallel data (step S7).

FIG. 5 is a conceptual diagram for explaining the reconstruction process executed in the nuclear medicine diagnostic apparatus 10. As shown in FIG. 5, the data processing circuit 23 of the nuclear medicine diagnosis apparatus 10 performs back projection by so-called direct method from the fan beam data when the fan beam data exists in the reconstruction area of the projection angle θ. To do. On the other hand, when there is no fan beam data in the reconstruction area (X, Y), back projection is performed using parallel data. As a result, volume data is created and a tomographic image of the subject is displayed on the display circuit 24 (step S8).

In the method described above, the interpolation processing is executed only in the back projection of step S7. On the other hand, in the conventional nuclear medicine diagnostic device, the fan-
In the process of parallel conversion and parallel beam back projection, a total of two interpolation calculations are executed. Therefore, according to the nuclear medicine diagnosis apparatus, it is possible to provide a tomographic image having a higher spatial resolution than the conventional configuration.

Further, for example, in the case of 180-degree collection for the heart using two opposed cameras, the conventional nuclear medicine diagnostic apparatus performs fan-parallel conversion, so the detector is rotated by an additional fan angle beyond 180 degrees. It was necessary to collect data. On the other hand, according to this nuclear medicine diagnostic apparatus, since reconstruction is performed by direct method back projection, only data for 180 degrees is needed and data for fan angles is not required. As a result, the working time is shortened and the burden on the operator and the patient can be reduced.

(Second Embodiment) In the second embodiment, the parallel data is converted into fan data (inverse fan-parallel conversion), and this is used once as the data of the peripheral portion of the fan beam data. A nuclear medicine diagnostic apparatus that provides a tomographic image with a high spatial resolution by using only the interpolation processing of 1. The configuration of the nuclear medicine diagnostic apparatus according to this embodiment is the same as that of the first embodiment.

FIG. 6 shows the process of photographing, data processing, and displaying.
It is the flowchart which showed the processing procedure which the nuclear medicine diagnostic apparatus 10 which concerns on 2nd Embodiment performs. In FIG.
With the same contents as in the first embodiment, steps S11, 1
Processing from 1'to step S15 is performed (step S1
1, 11'-step S15).

Next, the fan beam data is converted into parallel beam data (inverse fan-parallel conversion) (step S16). At this time, at the same time, the data after the inverse fan-parallel conversion is multiplied by the reciprocal of the weight by the fan beam opening angle θ (1 / cos θ). This 1 / c
By integrating osθ, the weight in the direct method reconstruction can be eliminated.

In step S16, the correction coefficient is added to the data after the inverse fan-parallel conversion, and the sensitivity between the data after the inverse fan-parallel conversion and the fan beam data is corrected. The coefficient for this sensitivity correction is
It is decided as follows.

FIG. 7 is a diagram for explaining a method of determining a correction coefficient to be added to the data after the inverse fan-parallel conversion in order to correct the difference in sensitivity with the parallel beam data. As shown in FIG. 7, in order to make the average in the effective visual field set for the parallel beam data the same as the average in the effective visual field of the data after the inverse fan-parallel conversion,
It is determined in advance as a coefficient to be added to the data after the inverse fan-parallel conversion. The determined coefficients are tabulated and stored in the memory.

The sensitivity correction in step S16 is not limited to the method using the above correction coefficient,
Anything can be used as long as it can achieve the same purpose. For example, as in the first embodiment, there is a method of obtaining a function of the sensitivity distribution curve of fan beam data and performing sensitivity correction of parallel data according to the function.

Next, the data after the inverse fan-parallel conversion is arranged around the fan data to generate composite data composed of the fan beam data and the data after the inverse fan-parallel conversion (step S17). That is, the composite data was obtained by using the fan beam data collected by using the fan beam collimator for the region important for diagnosis including the effective visual field, and obtained by the inverse fan-parallel conversion for the other regions. Data is adopted.

Next, the synthesized data is multiplied by a one-dimensional convolution function (reconstruction function) to perform convolution (step S18), and reconstruction is performed (step S19).

FIG. 8 is a conceptual diagram for explaining the reconstruction process executed in the nuclear medicine diagnostic apparatus 10 according to this embodiment. As shown in FIG. 8, the nuclear medicine diagnostic device 10
Data processing circuit 23 performs back projection by a so-called direct method on the composite data composed of the fan beam data and the data after the inverse fan-parallel conversion.
As a result, volume data is created and a tomographic image of the subject is displayed or displayed in color 24 (step S2).
0).

In the method described above, the interpolation processing is executed only in the back projection of step S19 for the region important for diagnosis including the effective visual field. Therefore, it is possible to provide a high-resolution tomographic image as compared with the conventional configuration in which interpolation calculation is executed twice in total in the process of fan-parallel conversion and parallel beam back projection.

Further, according to this nuclear medicine diagnostic apparatus, since reconstruction is performed by direct method back projection, data for the fan angle is not required, and therefore only data for 180 degrees need be collected. Thereby, the working time can be shortened.

The present invention has been described above based on the embodiments. However, within the scope of the idea of the present invention, those skilled in the art can come up with various modifications and modifications, and the modifications and modifications. It is understood that the examples also belong to the scope of the present invention.

For example, the technical idea of the present invention can be applied to an apparatus that reconstructs an image using parallel beam data and fan beam data, such as an X-ray CT apparatus or an image processing apparatus.

Further, the respective embodiments may be combined as appropriate as much as possible, in which case the combined effects can be obtained. Further, the embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, the problem described in the section of the problem to be solved by the invention can be solved, and the effect described in the section of the effect of the invention can be solved. When at least one of the above is obtained, the configuration in which this constituent element is deleted can be extracted as the invention.

[0062]

As described above, according to the present invention, the number of interpolation calculations can be reduced by performing direct method reconstruction, and a nuclear medicine diagnostic apparatus, an image processing apparatus and an image reconstruction apparatus which can provide a diagnostic image with high spatial resolution. The method can be realized.

[Brief description of drawings]

FIG. 1 shows a configuration of a nuclear medicine diagnostic device 10 according to the present embodiment.

FIG. 2 is a configuration example in which radiation is collected from a heart of a subject by using a two-dimensional detector 11A having a fan-beam collimator and a two-dimensional detector 11B having a parallel-beam collimator. It is the figure which showed.

FIG. 3 is a flowchart showing a processing procedure executed by the nuclear medicine diagnostic apparatus 10 before imaging, data processing, and display.

FIG. 4 is a diagram for explaining a method of determining a correction constant to be added to parallel data in order to correct a difference in sensitivity from parallel.

FIG. 5 is a conceptual diagram for explaining a reconstruction process executed in the nuclear medicine diagnostic device 10 according to the first embodiment.

[Fig. 6] Fig. 6 is a diagram showing a second process before photographing, data processing, and display.
6 is a flowchart showing a processing procedure executed by the nuclear medicine diagnostic device 10 according to the embodiment.

FIG. 7 is a diagram for explaining a method of determining a correction coefficient to be added to the data after the inverse fan-parallel conversion in order to correct the difference in sensitivity with the parallel beam data.

FIG. 8 is a conceptual diagram for explaining a reconstruction process executed in the nuclear medicine diagnostic device 10 according to the second embodiment.

FIG. 9 is a diagram for explaining data processing in a conventional nuclear medicine diagnostic apparatus.

[Explanation of symbols]

10 ... Nuclear medicine diagnostic device 11A. 11B ... Two-dimensional detector 13 ... Sleeper 14 ... Rotating frame 15 ... Bed movement / shift / up / down control unit 16 ... Whole rotation control unit 17 ... Detector movement / tilt / shift control unit 18 ... Collection controller 22 ... Collection memory 23 ... Data processing circuit 24 ... Display circuit 25 ... Controller 26. Moving / tilting / shifting mechanism 27 ... Image memory

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2G088 EE02 FF04 GG20 GG21 JJ05                       JJ06 JJ12 JJ13 KK33 LL12                 5B057 AA07 BA03 BA24 BA26 CA08                       CA13 CA16 CB08 CB13 CB16                       CC01 CE08 CH18

Claims (9)

[Claims] 1. A first collimator for collimating the radiation emitted from a radioisotope administered to a subject into a fan beam shape, and detecting the incident radiation.
And a second collimator for collimating the radiation emitted from the subject into a parallel beam shape, the second detection means for detecting the incident radiation, and the first and second detectors. A moving mechanism that rotates the subject about a predetermined angle, fan beam data about the predetermined angle detected by the first detector, and parallel beam data about the predetermined angle detected by the second detector. And a means for reconstructing the fan beam data, the direct method back projection of the fan beam data is performed for the area, and the parallel beam data back projection is performed for the area where the fan beam data is not present. A nuclear medicine diagnostic apparatus comprising: an image reconstructing unit for performing the above. 2. A third collimator for collimating radiation emitted from the subject into a fan beam shape,
The reconstructing means further includes third detecting means for detecting incident radiation, and the second reconstructing means rotates the third detecting means together with the first and second detecting means to obtain second fan beam data. In this case, the direct method back projection is performed based on the third fan beam data obtained by arithmetically averaging the first and second fan beam data, The nuclear medicine diagnostic apparatus according to claim 1, wherein . 3. A first collimator for collimating the radiation emitted from the radioisotope administered to the subject into a fan beam shape, and detecting the incident radiation.
And a second collimator for collimating the radiation emitted from the subject into a parallel beam shape, the second detection means for detecting the incident radiation, and the first and second detectors. A moving mechanism that rotates the subject about a predetermined angle, and a data conversion unit that converts the parallel beam data about the predetermined angle detected by the second detector into fan beam data to obtain pseudo fan beam data. And replacing the region of the pseudo fan beam data, which corresponds to the fan beam data for the predetermined angle detected by the first detector, with the fan beam data obtained by the first detector. A composite data generating unit for generating the composite data; and an image reconstructing unit for performing the direct method back projection of the composite data. Nuclear medicine diagnostic apparatus according to claim the door. 4. A third collimator for collimating the radiation emitted from the subject into a fan beam shape,
The composite data generation means further includes a third detection means for detecting incident radiation, and the combined data generation means defines a region corresponding to the fan beam data in the pseudo fan beam data as the first and second detection means. When the second fan beam data is acquired by rotating the third detecting means together with the above, the composite data is obtained by replacing the first and second fan beam data with the third fan beam data obtained by averaging. The nuclear medicine diagnostic device according to claim 2, wherein 5. When n is a natural number, the predetermined angle is
The nuclear medicine diagnostic device according to claim 1 or 3, wherein the nuclear medicine diagnostic device is 180 × n degrees. 6. Fan beam data acquired based on a fan beam obtained by collimating radiation emitted from a radioisotope inside an object into a fan beam shape, and radiation emitted from the subject into a parallel beam shape. An image processing device for reconstructing a concentration distribution of a radioisotope from parallel data acquired based on a collimated parallel beam, wherein an area where the fan beam data is present is a direct method background of the fan beam data. An image processing apparatus comprising: an image reconstructing unit that performs projection and performs back projection of the parallel beam data on an area where the fan beam data does not exist. 7. Fan beam data acquired based on a fan beam obtained by collimating radiation emitted from a radioisotope inside an object into a fan beam shape, and radiation emitted from the subject into a parallel beam shape. An image processing apparatus for reconstructing a concentration distribution of a radioisotope from parallel data acquired based on a collimated parallel beam, wherein the parallel beam data is converted into fan beam data to obtain pseudo fan beam data. A data conversion unit that generates composite data by replacing a region of the pseudo fan beam data corresponding to the fan beam data with the fan beam data, and a direct method back of the composite data. Image reconstructing means for performing projection, An image processing device characterized by: 8. Fan beam data acquired based on a fan beam obtained by collimating radiation emitted from a radioisotope inside an object into a fan beam shape, and radiation emitted from the subject into a parallel beam shape. An image processing method for reconstructing a concentration distribution of a radioisotope from parallel data acquired based on collimated parallel beams, wherein a direct method back-up of the fan beam data is performed for an area where the fan beam data exists. The image processing method is characterized by performing projection and performing back projection of the parallel beam data on an area where the fan beam data does not exist. 9. Fan beam data acquired based on a fan beam obtained by collimating radiation emitted from a radioisotope inside an object into a fan beam shape, and radiation emitted from the subject into a parallel beam shape. An image processing method for reconstructing a concentration distribution of a radioisotope from parallel data acquired based on a collimated parallel beam, the pseudo beam data being generated by converting the parallel beam data into fan beam data. Of the pseudo fan beam data, a region corresponding to the fan beam data is replaced with the fan beam data to generate synthetic data, and the direct method back projection of the synthetic data is performed. Image processing method.