JP2008196899A - Scattering correction method of nuclear medicine diagnostic apparatus and nuclear medicine diagnostic apparatus provided with this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly perform correction while enhancing correction accuracy, by utilizing the property of scattering components in photon detectors in a multilayer structure. <P>SOLUTION: A scattering correction section 21 estimates a scattering component concerning a second photon detecting element where the scattering component is smaller, out of the photon detectors 17, and moreover finds a true component concerning the second photon detecting element on the basis of the scattering component. Next, based on the true component and a ratio, the correction section 21 finds a true component concerning a first photon detecting element. A reconstruction section 25 reconstructs an RI distribution image on the basis of the true component. Since the scattering component is estimated in this way by the second photon detecting element where the scattering component is smaller and the true component is larger, an estimation error can be reduced, and moreover the components can be found by simple operations. Accordingly, an RI distribution image of high image quality can be acquired by short-time correction work while enhancing the accuracy of scattering correction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a scattering correction method for a nuclear medicine diagnostic apparatus that detects a photon such as an X-ray or a γ-ray and makes a diagnosis based on position information, and a nuclear medicine diagnostic apparatus including the same, and more particularly, to detect a photon having a multilayer structure. The present invention relates to a technique for correcting scattering generated outside the vessel.

  X-rays, γ-rays, and the like are photons with high energy, and thus scatter, particularly Compton scattering, by interaction with a substance (see, for example, Non-Patent Document 1). Since this Compton scattering becomes more prominent as the photon energy increases, it becomes a particular problem in a positron tomography apparatus (also called a positron CT apparatus or PET apparatus) in a medical diagnostic apparatus (see, for example, Patent Document 1).

  A nuclear medicine diagnostic apparatus such as a positron CT apparatus has a function of calculating position information of a light source (radiation source) from position information of a detector and generating a medical image from the position information. Therefore, the quality of medical images is improved by obtaining detailed detector position information. As an example, a detector is subdivided to obtain position information in the plane direction, and a multilayered DOI (Depth Of Interaction) detector is used to obtain position information in the depth direction (for example, Non-Patent Document 2).

In addition, when Compton scattering occurs in the detector, output may be obtained from a plurality of detection elements. In order to detect such Compton scattering, a detector capable of obtaining detailed position information (for example, a multi-anode photomultiplier tube) is used (for example, see Non-Patent Document 3). .
Nuclear Encyclopedia “Interaction between γ-rays and substances” http://sta-atm.jst.go.jp:8080/03060306_1.html Japanese Patent Laid-Open No. 7-113873 "DOI measurement device" http://www.nirs.go.jp/usr/medical-imaging/ja/study/jPET_D4_2006/p87_90.pdf `` Analysis of interaction in detector '' http://www.nirs.go.jp/usr/medical-imaging/ja/study/jPET_D4_2006/p87_90.pdf

However, the conventional example having such a configuration has the following problems.
That is, the scattering component deteriorates the position information of the light source, and as a result, the image quality is deteriorated. Therefore, although the scattering component is corrected, the correction accuracy is generally poor with a simple correction method, and the complicated correction method based on a complicated calculation using a large amount of information requires an enormous amount of time for analysis. There is a problem that requires. In addition, there is a problem that the S / N is deteriorated when correction is performed to limit the information based on the scattering component.

  The present invention has been made in view of such circumstances, and by making use of the characteristics of the scattering component in the multi-layer photon detector, correction can be performed in a short time while improving the correction accuracy. It is an object of the present invention to provide a scattering correction method for a nuclear medicine diagnostic apparatus and a nuclear medicine diagnostic apparatus including the same.

In order to achieve such an object, the present invention has the following configuration.
That is, the invention according to claim 1 is a scattering of a nuclear medicine diagnostic apparatus having a multi-layered photon detector having a first photon detection element on the light source side and a second photon detection element on the back side. In the correction method, (a) a scattering component is estimated as a second scattering component for the second count value by the second photon detection element, and the second photon detection element by the second photon detection element is estimated based on the second scattering component. A process of obtaining a true component as a second true component for a count value of 2, and (b) a ratio of the second true component to the first count value and the second count value. And a step of obtaining a true component as the first true component for the first count value by the first photon detection element based on the count rate.

  [Operation / Effect] According to the first aspect of the present invention, in the photon detector having a multilayer structure including the first photon detection element on the light source side and the second photon detection element on the back side, the scattering component is provided. The count value by the first photon detection element and the second photon detection element are different from each other, whereas the count value by the true component is almost the same between the first photon detection element and the second photon detection element and is unchanged. Focus on the characteristic of being. Since the energy of the scattered component is reduced, the scattered photon component is detected more by the first photon detection element on the light source side than the second photon detection element on the back side. Therefore, first, the scattering component is estimated as the second scattering component for the second count value by the second photon detection element having a small amount of scattering component, and the second photon detection element by the second photon detection element is based on the second scattering component. For the count value, the true component is determined as the second true component. Next, based on the second true component and the count rate that is the ratio of the first count value and the second count value, the true component for the first count value by the first photon detection element As the first true component. As described above, since the scattering component is estimated by the second photon detection element having a small amount of the scattering component and a large amount of the true component, the estimation error can be reduced and can be obtained by a simple calculation. Therefore, correction can be performed in a short time while increasing the correction accuracy of scattering.

  Further, in the present invention, after the step (b), (c) a scattering component is estimated as the first scattering component for the first count value by the first photon detection element, and the first scattering component is Based on the first count value by the first photon detection element, the step of obtaining a true component as another first true component, the first true component obtained in the step (b), It is preferable to weight each of the other first true components obtained in the step (c) to obtain the first true component (claim 2). Instead of obtaining the true component of the first photon detection element only from the second photon detection element, the first photon detection element may be used. That is, the scattering component is estimated as the first scattering component for the first count value by the first photon detection element, and the true component for the first count value by the first photon detection element based on the first scattering component As another first true component. Next, the first true component obtained earlier and the other first true component are respectively weighted to obtain the first true component, so that the first true component can be obtained with higher accuracy. Can be obtained.

  The invention according to claim 3 is a nuclear medicine diagnostic apparatus for detecting photons from a subject, comprising a bed on which the subject is placed, a first photon detection element on the bed side, and a back side thereof. A photon detector for detecting a photon emitted from a radionuclide administered to a subject, and a second count value by the second photon detection element. A first scattering component is estimated as a second scattering component and a true component is obtained as a second true component for the second count value of the second photon detection element based on the second scattering component. Based on the calculation means, the second true component, and a count rate that is a ratio of the first count value and the second count value, a first meter by the first photon detection element is used. Find the true component of the number as the first true component A second computing means, it is characterized in that it comprises a and a reconstructing means for reconstructing an RI distribution image based on the first true component and said second real component.

  [Operation / Effect] According to the invention described in claim 3, first, the first calculation means is a scattering component for the second count value by the second photon detection element of the photon detector having a small scattering component. Is estimated as the second scattering component, and a true component is obtained as the second true component for the second count value by the second photon detection element based on the second scattering component. Next, based on the second true component and the count rate that is the ratio of the first count value and the second count value, the second calculation means performs the first photon detection element by the first photon detection element. The true component is obtained as the first true component for the count value of. Then, reconstruction means reconstructs the RI distribution image based on the first true component and the second true component. As described above, since the scattering component is estimated by the second photon detection element having a small amount of the scattering component and a large amount of the true component, the estimation error can be reduced and can be obtained by a simple calculation. Therefore, it is possible to obtain a high-quality RI distribution image by performing correction in a short time while increasing the correction accuracy of scattering.

  Further, in the present invention, a scattering component is estimated as a first scattering component for the first count value by the first photon detection element, and the first photon detection element by the first photon detection element is based on the first scattering component. A third computing means for obtaining a true component of the count value as a first true component different from the second computing means; the first true component and the other first true It is preferable that the apparatus further includes fourth calculation means for weighting each component to obtain a first true component (claim 4). The third computing means estimates the scattered component as the first scattered component for the first count value by the first photon detecting element, and the first calculation by the first photon detecting element based on the first scattered component. The true component of the numerical value is obtained as another first true component. Next, the fourth calculation means weights the first true component obtained earlier and the other first true component to obtain the first true component, thereby further increasing the first true component. The first true component can be obtained with high accuracy.

  Further, in the present invention, when the count rate sequentially obtained at the time of photographing increases, the collection process is performed so that the total count value increases, and when the count rate decreases, the collection process decreases the total count value. It is preferable to further comprise a control means for performing (Claim 5). In general, since the scattering component is different for each measurement site, the count rate varies for each measurement site. Therefore, when there are many scattering components, the count value at the first photon detection element containing a large amount of scattering components is larger than the count value of the second photon detection element, and the count rate becomes larger. Collection processing is performed so that the numerical value increases. For example, the collection time is increased or the moving speed of the bed is decreased. On the other hand, when the scatter component is small, the count rate is small, so that the control means performs a collection process so that the total count value decreases. For example, the collection time is shortened or the moving speed of the bed is increased. Thus, by performing the collection process flexibly, it is possible to maintain a certain level of image quality regardless of the measurement site.

  According to the scatter correction method of the nuclear medicine diagnostic apparatus according to the present invention, the scatter component is estimated as the second scatter component for the second count value by the second photon detection element having a small scatter component, and the second scatter component is estimated. Based on the above, the true component is obtained as the second true component for the second count value by the second photon detection element. Next, based on the second true component and the count rate that is the ratio of the first count value and the second count value, the true component for the first count value by the first photon detection element As the first true component. As described above, since the scattering component is estimated by the second photon detection element having a small amount of the scattering component and a large amount of the true component, the estimation error can be reduced and can be obtained by a simple calculation. Therefore, correction can be performed in a short time while increasing the correction accuracy of scattering.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram illustrating a schematic configuration of a positron CT apparatus according to an embodiment, and FIG. 2 is a longitudinal sectional view illustrating a schematic configuration of a photon detector.

  The positron CT apparatus includes a gantry unit 1, a data collection system 3, and a data processing unit 5. The gantry unit 1 includes a bed 7 and a gantry 9 on which a subject M to which a positron emitting nuclide is administered is placed. The bed 7 includes a base 11 that can be raised and lowered, and a top plate 13 that is movable in the horizontal direction (Z direction) above the base 11.

  The gantry 9 has an opening 15 in the center that can accommodate the subject M together with the top plate 13. A plurality of photon detectors 17 (described later in detail) for detecting positrons (photons) emitted from the subject M are embedded around the opening 15. Outputs from the plurality of photon detectors 17 are provided to the data collection system 3.

  The data collection system 3 includes a data collection unit 19, a scatter correction unit 21, and a position information calculation unit 23. The data collection unit 19 includes an amplifier, an ADC (analog-digital converter), a TDC (time-digital converter), a delay circuit, a double event determination unit, and the like, and relates to photons incident on the pair of photon detectors 17 at the same time. Collect and digitize the signal. As will be described later, the scatter correction unit 21 estimates a scatter event that has occurred outside the photon detector 17, for example, the subject M, and obtains a true component. The position information calculation unit 23 calculates the center of gravity based on the output of the photon detector 17 and the true component from the scattering correction unit 21 to obtain the position information and depth information on which the photon has interacted.

  The data processing unit 5 includes a reconstruction unit 25, a control unit 27, a display device 29, an instruction unit 31, and a drive unit 33. The reconstruction unit 25 reconstructs the RI distribution image of the subject M based on the position information and depth information from the position information calculation unit 23, the collected signal from the data collection unit 19, and the separately collected transmission data. The control unit 27 advances or retracts the top panel 13 via the drive unit 33 based on processing for displaying the RI distribution image on the display device 29 based on the data of the reconstruction unit 25 and instructions via the instruction unit 31 such as a mouse. The process to drive, the instruction | indication of the collection start with respect to the data collection system 3, etc. are performed.

The photon detector 17 is configured, for example, as shown in FIG.
That is, the photon detector 17 is a so-called two-layer DOI detector configured by combining a plurality of different photon detection elements and further stacking them. Specifically, a first photon detection element 35 and a second photon detection element 37 are provided in order from the side where the light source is emitted from which photons are emitted. A light guide 39 is disposed on the second photon detection element 37 side, and a plurality of photomultiplier tubes 41 are disposed on the ride guide 39. Further, each of the first photon detection element 35 and the second photon detection element 37 is constituted by a plurality of blocks. For example, the first photon detection element 35 is made of LSO (ruthium silicon oxide), and the second photon detection element 37 is made of GSO (silicate / gatrinium). The photon detector 17 having such a configuration can obtain position information (x, y) and depth information (d) in the horizontal direction of the portion interacting with the photon.

  Next, with reference to FIGS. 3 to 6, a method for obtaining a true component by the scattering correction unit 21 will be described. 3 is a schematic diagram showing the distribution of the radiation sources of each layer by the true component, FIG. 4 is a schematic diagram showing the distribution of the radiation sources of each layer when a scattering component is included, and FIG. FIG. 6 is a schematic diagram showing a distribution of scattered components in the second photon detection element, and FIG. 6 is a schematic diagram showing an estimated distribution of true components in the first photon detection element.

  Among the photons incident on the photon detector 17, the true photon that has not been scattered has a constant energy because the photon emitted from the radiation source is monochromatic light. Therefore, a true photon has a constant mass cross section in the first photon detection element 35 and the second photon detection element 37 from a physical process. That is, in the photon detector 17 shown in FIG. 2, the mass cross section of a photon having a certain energy at the first photon detection element 35 is σ (35) and the mass cross section at the second photon detection element 37. When σ (37) is set, the mass cross-sectional area is as follows.

  σ (35) / σ (37) = Const (1)

  Here, a φ15 cm cylindrical phantom in the case where Const = 2 in Equation (1) is taken as an example, and an example of the distribution in the x direction of the radiation source by only the true component emitted from the cylindrical phantom. As shown in FIG.

  On the other hand, scattered photons lose their energy compared to true photons, and because of their physical processes, low energy photons have an exponential increase in photoelectric effect and mass cross section compared to high energy photons. More scattered components are detected by the first photon detection element 35 closer to the light source, and more true components are detected by the second photon detection element 37 far from the light source. This indicates that the true component / scattering ratio is high.

  Here, FIG. 4 shows an x distribution of a radiation source including a scattering component when a φ15 cm cylindrical phantom is measured. Since both the component EL35-1 of the first photon detection element 35 and the component EL37-1 of the second photon detection element 37 have scattering components, the distribution is only the true component, as compared with FIG. Both distributions are a little raised. However, the swell is smaller in the distribution of the second photon detection element 37 having a small scattering component by the component EL 37-1 than in the first photon detection element 35.

  Therefore, first, as shown in FIG. 5, the scattering component SC37 is estimated for the component EL37-1 of the second photon detection element 37 containing a lot of true components. Next, as shown in FIG. 6, the true component TE37-1 of the second photon detection element 37 is extracted based on the scattering component SC37. Further, as shown in FIG. 6, the first photon detection element 35 is obtained by multiplying the true component TE37-1 of the second photon detection element 37 by a constant (Const multiple) according to the relationship of the above expression (1). The true component TE35-1 can be estimated.

  The above-described method is executed by the scattering correction unit 21. The scattering component varies between the first photon detection element 35 and the second photon detection element 37, whereas the distribution of the true component is the first. This is based on the fact that the photon detection element 35 and the second photon detection element 37 do not change.

  By applying the above method to the position information y and the depth information d, the scattering correction unit 21 obtains scattering correction data.

  The above constant Const corresponds to the counting rate in the present invention. The component EL35-1 corresponds to the first count value in the present invention, the component EL37-1 corresponds to the second count value in the present invention, and the scattering component SC37-1 This corresponds to the second scattering component in the present invention. The true component TE37-1 corresponds to the second true component in the present invention, and the true component TE35-1 corresponds to the first true component in the present invention.

  The scattering correction unit 21 corresponds to the first calculation unit and the second calculation unit in the present invention, and the reconstruction unit 25 corresponds to the reconstruction unit in the present invention.

  Next, the operation of the positron CT apparatus will be described with reference to FIG.

Step S1
Data collection is performed with the subject M placed on the bed 7.

Step S2
The scattering correction unit 21 estimates the scattering component SC37-1 of the second photon detection element 37 by the method described above.

Step S3
The scattering correction unit 21 obtains the true component TE37-1 of the second photon detection element 37 based on the scattering component SC37-1.

Step S4
The scattering correction unit 21 obtains the true component TE35-1 of the first photon detection element 35 based on the true component TE37-1 and the constant Const. Such processing is performed for the position information y and the depth information d.

Step S5
Based on the true component TE37-1 and true component TE35-1 of each piece of position information (x, y) and depth information (d), the position information calculation unit 23 calculates the position information (x, y) of photons and Depth information (d) is obtained.

Step S6
The reconstruction unit 25 reconstructs the RI distribution image based on the photon position information (x, y) and the depth information (d). The RI distribution image obtained in this way is displayed on the display device 29.

  As described above, according to the apparatus of this embodiment, the scattering correction unit 21 estimates the scattering component SC37 for the component EL37-1 by the second photon detection element 37 having a small scattering component in the photon detector 17, and the scattering. Based on the component SC37, a true component TE37-1 is obtained for the component 37-1 by the second photon detection element 37. Next, based on the true component TE37-1, and the constant Const that is the ratio of the component EL35-1 to the component EL37-1, the scattering correction unit 21 uses the first photon detection element 35 to generate the component EL35-1. A true component TE37-1 is obtained for. Then, the reconstruction unit 25 reconstructs the RI distribution image based on the true component TE35-1 and the true component TE37-1. Thus, since the scattering component is estimated by the second photon detection element 37 having a small amount of the scattering component and a large amount of the true component, the estimation error can be reduced and can be obtained by a simple calculation. Therefore, it is possible to obtain a high-quality RI distribution image by performing correction in a short time while increasing the correction accuracy of scattering.

<Modification>
In the above-described embodiment, the true component TE35-1 of the first photon detection element 35 is obtained from only the component EL37-1 of the second photon detection element 37. However, the first photon detection element is as follows. 35 true components may be obtained.

  Please refer to FIG. FIG. 8 is a flowchart showing a modified example of the operation. Steps S1 to S4 and S5 and S6 in this flowchart are substantially the same as those in the above-described embodiment, and thus description thereof is omitted.

Step S2a
The scattering correction unit 21 estimates the scattering component SC35 from the component EL35-1 of the first photon detection element 35 (see FIG. 4).

Step S3a
The scatter correction unit 21 obtains the true component TE35-2 of the first photon detection element 35 based on the scatter component SC35.

Step S4a
The scatter correction unit 21 includes the true component TE35-1 of the first photon detection element 35 and the true component TE35-2 of the first photon detection element 35, which are obtained as in the above-described embodiment. Based on this, another true component TE35-3 of the first photon detection element 35 is obtained. In that case, it is preferable to weight each of the true components TE35-1 and TE35-2. As the weighting, it is exemplified that the true component TE35-1 having high accuracy is handled larger than the true component TE35-2.

  As described above, the true component TE35-3 of the first photon detection element 35 is obtained based on both the detection elements 35 and 37, and reconfiguration is performed based on this.

  Note that the above-described scattering correction unit 21 corresponds to the third calculation means in the present invention, and the true component TE35-3 corresponds to another first true component in the present invention.

  As described above, according to this modification, the true component TE35-1 obtained earlier and another true component TE35-2 are respectively weighted to be the true component TE35-3. The true component TE35-3 can be obtained for the first photon detection element 35 with higher accuracy.

  The present invention is not limited to the above-described embodiment, and can be modified as follows.

  (1) In the above-described embodiment, one photon detector 17 includes a plurality of monoanode type photomultiplier tubes 41. However, the photomultiplier tube may be a multi-anode type. Thereby, the photomultiplier tube 41 can be reduced and the cost of the photon detector 17 can be suppressed.

  (2) In the above-described embodiment, when the count rate sequentially obtained at the time of data collection is increased, the collection process is performed so that the total count value is increased. When the count rate is decreased, the total count value is It is preferable that the control unit 27 performs an operation so as to perform collection processing so as to reduce the number.

  Processing in this case will be described with reference to FIG. FIG. 9 is a flowchart showing another operation.

After the data collection, the total count value is compared with the previous total count value, and the data collection is repeatedly performed while branching the process according to the result (steps S10 to S14).
That is, when the total count value is larger than the previous total count value, the control unit 27 operates the drive unit 33 to slow down the moving speed of the bed 13 (step S12). On the other hand, when the total count value is smaller than the previous total count value, the drive unit 33 is operated to increase the moving speed of the bed 13 (step S13). When there is no change in them, the operation of the drive unit 33 is not performed, and the same movement speed as before is maintained. When the thickness varies depending on the part of the body like the subject M, the scattering component varies depending on the part, but the control unit 27 operates the drive unit 33 in this way, so that a certain level of image quality can be obtained regardless of the measurement part. Can be maintained.

  Instead of changing the moving speed of the bed 13, the moving speed of the gantry 9 may be adjusted, or the data collecting system 3 may be operated so as to adjust the collecting time.

  (3) In the above-described embodiments, the positron CT apparatus has been described as an example. However, the present invention can be applied even to a nuclear medicine diagnostic apparatus (SPECT apparatus) using a single photon emission nuclide.

It is a block diagram which shows schematic structure of the positron CT apparatus which concerns on an Example. It is a longitudinal cross-sectional view which shows schematic structure of a photon detector. It is a schematic diagram which shows distribution of the radiation source of each layer by a true component. It is a schematic diagram which shows distribution of the radiation source of each layer in case a scattering component is included. It is a schematic diagram which shows distribution of the scattering component in a 2nd photon detection element. It is a schematic diagram which shows the estimated distribution of the true component in a 1st photon detection element. It is a flowchart which shows operation | movement. It is a flowchart which shows the modification of operation | movement. It is a flowchart which shows another operation | movement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Gantry part 2 ... Data collection system 3 ... Data processing part 7 ... Bed 9 ... Gantry 13 ... Top plate 17 ... Photon detector 19 ... Data collection part 21 ... Scatter correction part 23 ... Position information calculation part 25 ... Reconstruction part DESCRIPTION OF SYMBOLS 27 ... Control part 29 ... Display apparatus 35 ... 1st photon detection element 37 ... 2nd photon detection element 39 ... Ride guide 41 ... Photomultiplier tube EL35-1 ... Component 1 of photon detection element EL37-1 ... Component of second photon detection element SC37 ... Scattering component of second photon detection element TE37-1 ... True component of second photon detection element TE35-1 ... True component of first photon detection element

Claims (5)

  In a scattering correction method for a nuclear medicine diagnostic apparatus having a multi-layered photon detector including a first photon detection element on the light source side and a second photon detection element on the back side thereof, (a) the second The scattering component is estimated as the second scattering component for the second count value by the photon detection element, and the true component for the second count value by the second photon detection element is set to the second based on the second scattering component. (B) based on the second true component and a count rate that is a ratio of the first count value and the second count value. And a step of obtaining a true component as a first true component for the first count value by the photon detection element.   The scatter correction method of the nuclear medicine diagnosis apparatus according to claim 1, wherein after the step (b), (c) a scatter component is used as a first scatter component for a first count value by the first photon detection element. And calculating a true component as another first true component for the first count value by the first photon detection element based on the first scattering component, and obtaining in the step (b) The first true component and the other first true component obtained in the step (c) are respectively weighted to obtain the first true component. Scatter correction method.   In a nuclear medicine diagnostic apparatus for detecting photons from a subject, a multi-layer comprising a bed on which the subject is placed, a first photon detection element on the bed side, and a second photon detection element on the back side A photon detector that detects photons emitted from a radionuclide administered to a subject and a second count value obtained by the second photon detection element is estimated as a second scattered component. And a first calculation means for obtaining a true component as a second true component for the second count value by the second photon detection element based on the second scattered component, and the second true component And a true component of the first count value by the first photon detection element based on a count rate that is a ratio between the first count value and the second count value. A second computing means to be obtained as a component; Nuclear medicine diagnosis apparatus characterized by comprising a reconstruction unit, a reconstructing an RI distribution image based on component and the second true components.   4. The nuclear medicine diagnosis apparatus according to claim 3, wherein a scattering component is estimated as a first scattering component for a first count value by the first photon detection element, and the first scattering component is estimated based on the first scattering component. Third arithmetic means for obtaining a true component for the first count value by the photon detection element as a first true component different from the second arithmetic means, the first true component and the separate And a fourth arithmetic means for weighting each of the first true components to obtain the first true component, and a nuclear medicine diagnostic apparatus.   In the nuclear medicine diagnostic apparatus according to claim 3 or 4, when the counting rate obtained sequentially at the time of imaging increases, collection processing is performed so that a total count value increases, and when the counting rate decreases, A nuclear medicine diagnosis apparatus, further comprising a control unit that performs collection processing so that the total count value is reduced.

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