JP4820561B2 - Nuclear medicine diagnostic equipment - Google Patents

Description

  The present invention relates to a nuclear medicine diagnostic apparatus that visualizes the distribution of a drug labeled with RI (Radioisotope) in a subject as an image, and more particularly to a technique for effectively correcting body motion of a subject. Is.

  In recent years, nuclear medicine diagnostic apparatuses such as SPECT (Single Photo Emission Tomography) apparatus, PET (Positron Emission Tomography) apparatus, or a SPECT / PET apparatus having the functions of both have been used in clinical practice and attracting attention.

  The SPECT apparatus detects radiation such as gamma rays emitted from an RI administered to a subject such as a patient with a radiation detector and acquires a distribution image of the RI within the subject, thereby It is a device that displays images and functional distribution images such as blood flow and fatty acid metabolism. The PET apparatus is an apparatus that includes a plurality of radiation detectors, and performs imaging by simultaneously detecting a pair of gamma rays emitted in opposite directions when positrons combine with electrons and disappear.

  The examination by such a nuclear medicine diagnostic apparatus is performed by rotating a detector for detecting radiation from the RI in the subject around the body axis of the subject. In this inspection, since the collection time in one projection is long, for example, an inspection time of about 20 to 30 minutes is required. Therefore, the subject often moves during the examination. Such movement of the subject (body movement) is one factor that degrades the image quality of the image, and reexamination may be required when the body movement is large. Therefore, in the nuclear medicine diagnostic apparatus, even when body motion occurs in the subject, data correction for correcting the influence and acquiring a good image, that is, processing related to so-called body motion correction is important.

  For example, when the subject moves the body position, the following body motion correction technique is used. First, the radiation from the RI administered to the subject is detected, a plurality of projection data is collected, and the projection data is added in the body axis direction of the subject to create a linogram. Next, the center of gravity of a predetermined region surrounding the region of interest (in-vivo region of image acquisition target; heart, liver, etc.) is calculated on this linogram, and the change in the center of gravity is obtained for each projection angle at the time of radiation detection. Then, assuming that the change in the center of gravity is due to the movement of the body position of the subject, each projection data is shifted in the body axis direction so that the position of the center of gravity is constant, thereby causing the body axis direction of the subject to be changed. Correct body movements.

  However, this method can correct body movement in the body axis direction of the subject, but includes a component in a direction perpendicular to the body axis direction when the body movement is performed in a direction other than the body axis direction. However, there is a problem that correction cannot be performed with high accuracy. In addition, in this method, since the predetermined area needs to be set around the site of interest, it can be applied only to the site of interest where a clear image can be displayed. Such a region of interest is currently limited to the heart, and the scope of application of the body motion correction method is greatly limited.

  By the way, a nuclear medicine diagnostic apparatus capable of executing rotation center correction as preprocessing before reconstructing collected projection data is widely used (see, for example, Patent Document 1). This rotation center correction is a process of correcting the projection data based on the measured value (correction amount) of the movement amount of the rotation center collected during periodic inspections. The measured value of the movement amount is acquired as follows, for example. First, a point source (point source) is arranged at the rotation center of the radiation detector, and projection data at a plurality of collection angles of the point source is collected by the radiation detector. Then, the deviation of the point source with respect to the image center of the projection data is measured for each collection angle. By calculating back the measurement result, the correction amount of the projection data collected in the actual inspection is determined. When the nuclear medicine diagnosis apparatus includes a plurality of radiation detectors, a correction amount is acquired for each detector.

  However, such a conventional rotation center correction is executed only in the pre-processing after collecting projection data, and therefore cannot be used to correct a temporary rotation center shift caused by the body movement of the subject. As a result, it has been difficult for conventional nuclear medicine diagnosis apparatuses to perform high-accuracy examinations due to the effect of deviations in projection data when body motion occurs.

JP 2001-59872 A

  The present invention has been made in view of such circumstances, and preferably performs body motion correction not only when the subject moves in the body axis direction but also when the subject moves in other directions. An object of the present invention is to provide a nuclear medicine diagnostic apparatus capable of performing the above.

  Further, the present invention provides a nuclear medicine diagnosis capable of preferably performing body motion correction by paying attention to the displacement of the entire body of the subject even when the image of the site of interest cannot be clearly displayed. Another object is to provide a device.

In order to solve the above-mentioned problem, the invention described in claim 1 includes a data collection means for detecting radiation emitted from a radioisotope administered into a subject and collecting two-dimensional projection data; A reconstruction processing means for correcting the influence of attenuation of the radiation when propagating in the subject with respect to the collected projection data, and generating three-dimensional reconstruction data based on the corrected projection data; , And a nuclear medicine diagnostic apparatus that displays on the display means a distribution image of the radioisotope in the subject based on the generated reconstruction data, obtained by the reconstruction processing means Estimating data creating means for projecting the reconstructed data in the same direction as the projection data to create two-dimensional estimated projection data; and an error between the created estimated projection data and the projection data. Error calculating means for calculating, and data correcting means for correcting the position of the projection data so that the calculated error is minimized, wherein the reconstruction processing means is the projection data whose position has been corrected. Reconstructing and creating new reconstructed data, the estimated data creating means creates new estimated projection data based on the new reconstructed data created by the reconstruction processing means, The error calculating unit calculates an error between the new estimated projection data and the collected projection data, and the data correcting unit is configured to reduce the error with respect to the new estimated projection data. by correcting the position of the projection data, perform sequential correction to correct the sum of the corrected correction amount so far with respect to the acquired projection data, said display means sequentially complement And displaying the distribution image of the radioisotope based on new reconstructed data.

In order to solve the above-mentioned problem, the invention according to claim 2 is the nuclear medicine diagnosis apparatus according to claim 1 , wherein the data correction means is controlled so as to make the error smaller than a predetermined value. The apparatus further includes means .

In order to solve the above-mentioned problem, the invention according to claim 3 is the nuclear medicine diagnosis apparatus according to claim 1, wherein the error is calculated by a predetermined value every time the error calculation means calculates the error. And whether to correct the data correction means until the predetermined value is not exceeded, generation of reconstruction data by the reconstruction means, creation of estimated projection data by the estimated data creation means, A controller for repeating the error calculation by the error calculation unit and the determination, and the display unit displays a distribution image of the radioisotope based on reconstruction data when the error does not exceed a predetermined value. And features.

  In order to achieve the above object, the invention according to claim 4 is the nuclear medicine diagnosis apparatus according to any one of claims 1 to 3, wherein the error calculation means calculates the invention. The apparatus further comprises data selection means for selecting a pair of the estimated projection data and the collected projection data whose error is equal to or greater than a predetermined value, and the projection data to be corrected by the data correction means is selected by the data selection means. The collected projection data of the pair obtained.

  In order to achieve the above object, the invention according to claim 5 is the nuclear medicine diagnosis apparatus according to any one of claims 1 to 3, wherein the display means is the collected information. The selection operation means for displaying the projected data and the estimated projection data superimposed on each other, and manually selecting the desired pair from the superimposed projection data and the estimated projection data The projection data to be corrected by the data correction unit is the collected projection data of the pair selected by the selection operation unit.

  In order to achieve the above object, the invention described in claim 6 is the nuclear medicine diagnosis apparatus according to any one of claims 1 to 5, wherein the display means includes the data correction. The projection data corrected by the means and the estimated projection data created by the estimated data creating means are superimposed and displayed, and the projected data displayed in superposition is matched with the display position of the estimated projection data. Display position movement operation means for manually moving the display position, and the reconstruction means reconstructs the projection data in which an error from the estimated projection data is adjusted by the movement by the display position movement operation means. The new reconstruction data is created, and the display means displays a distribution image of the radioisotope based on the new reconstruction data.

  According to the nuclear medicine diagnosis apparatus of the present invention as set forth in claim 1, the estimated data creating means projects the three-dimensional reconstruction data in the same direction as the projection data is collected to create the two-dimensional estimated projection data. Then, the error calculation means calculates an error between the estimated projection data and the projection data, and the data correction means corrects the projection data so as to reduce the error. Therefore, based on the two-dimensional estimated projection data, it is possible to perform body motion correction in the body axis direction of the subject and the direction orthogonal thereto.

  Further, since the body motion correction is automatically performed based on the estimated projection data, it is possible to suitably perform the body motion correction even when the image of the site of interest cannot be clearly displayed.

In addition , the estimated projection data can be sequentially generated based on the previous correction result, and the projection data can be sequentially corrected so that the error from the estimated projection data becomes small. Is possible.

  An example of a preferred embodiment of a nuclear medicine diagnosis apparatus according to the present invention will be described in detail with reference to the drawings. Hereinafter, a SPECT apparatus which is an example of a nuclear medicine diagnostic apparatus according to the present invention will be described. Note that the configuration and processing according to the present invention in a nuclear medicine diagnosis apparatus such as a PET apparatus or a SPECT / PET apparatus are the same as those of the SPECT apparatus described below.

[Configuration of nuclear medicine diagnostic equipment]
FIG. 1 shows a schematic configuration of the nuclear medicine diagnostic apparatus of the present embodiment. The nuclear medicine diagnostic apparatus 1 shown in the figure detects the radiation as a configuration for collecting two-dimensional projection data of radiation (gamma rays) emitted from the RI in the subject in the nuclear medicine examination (SPECT examination). A position calculation unit 3 including two-dimensional detectors 2A, 2B, and 2C (sometimes collectively referred to as "detector 2") and an electric circuit that calculates a detection position of radiation from the detection results of each of the detectors 2. And a data collection unit 4 that receives the calculation result by the position calculation unit 3 and collects the data as projection data by each detector 2. Projection data collected by the data collection unit 4 (sometimes abbreviated as collected projection data) is transmitted to the preprocessing unit 5. Here, the detector 2, the position calculation unit 3, and the data collection unit 4 constitute a data collection unit according to the present invention.

  The detectors 2A, 2B, and 2C are coaxially arranged with the body axis of the subject as the center. The detectors 2A, 2B, and 2C are provided with a scintillator that converts the radiation into an optical signal on the incident surface side on which the radiation is incident. Includes a photomultiplier tube that amplifies the optical signal from the scintillator and converts it into an electrical signal. On the incident surface of the scintillator, lead collimators for limiting the incident direction of radiation are arranged vertically and horizontally. The detector 2 detects the radiation propagated in the subject while being rotationally driven around the body axis of the subject by a rotation driving device including a motor and the like. In this embodiment, three detectors are provided. However, the nuclear medicine diagnosis apparatus according to the present invention is not limited to this, and may be configured to have one or two detectors, for example.

  The preprocessing unit 5 constitutes preprocessing means in the present invention, and various correction processes are performed on the collected projection data collected by the data collecting unit 4 as preprocessing for creating an image inside the subject. Apply. For this purpose, the pre-processing unit 5 includes the scattering correction means 5A for performing scattered ray correction for correcting the influence of attenuation caused by Compton scattering when the radiation propagates in the subject, and each detector 2 rotating as described above. Rotation center correction means 5B for performing rotation center correction for correcting deviation of projection data caused by movement of the rotation center position when rotated by the driving device, and uniformity correction for correcting the uniformity of the collected projection data. Uniformity correction means 5C to be performed. These correction processes are executed according to a conventional procedure. The preprocessing unit 5 may include at least one of these correction units, but preferably includes all of them in order to perform inspection with high accuracy. The collected projection data that has been processed by the preprocessing unit 5 is transmitted to the reconstruction unit 6 and the control unit 8.

  The reconstruction processing unit 6 constitutes the reconstruction processing means of the present invention. The reconstruction processing unit 6 receives the two-dimensional projection data preprocessed by the preprocessing unit 5 and receives a three-dimensional back projection method or a three-dimensional fast Fourier transform. The projection data is reconstructed by a known method such as the (FFT) method to generate three-dimensional reconstruction data. In addition, the reconstruction processing unit 6 includes attenuation correction means 6A that corrects the attenuation effect of the intensity received when the radiation from the RI propagates through the subject. The reconstruction data created by the reconstruction processing unit 6 is transmitted to the estimated data creation unit 7 and the control unit 8.

  The estimated data creation unit 7 constitutes estimated data creation means of the present invention, and creates two-dimensional estimated projection data based on the reconstruction data from the reconstruction processing unit 6. The method of creating estimated projection data is executed by projecting (adding, line integration, etc.) three-dimensional reconstruction data in the same projection direction as that of the collected projection data. The created estimated projection data is transmitted to the control unit 8. The estimated projection data is data for correcting the collected projection data and estimating the correction amount for correcting the body motion of the subject.

  The control unit 8 stores the collected projection data transmitted from the preprocessing unit 5 in the collected projection data storage unit 9A of the storage unit 9, and estimates the estimated projection data transmitted from the estimated data creation unit 7 in the storage unit 9. A process of saving in the projection data storage unit 9B and a process of saving the reconstruction data transmitted from the reconstruction processing unit 6 in the reconstruction data storage unit 9C of the storage unit 9 are executed. These data stored in the storage unit 9 are appropriately called by the control unit 8 and used for various processes.

  Further, the control unit 8 receives an operation signal from the operation unit 10 and performs control for causing the nuclear medicine diagnosis apparatus to execute processing according to the operation signal. Here, the operation unit 10 constitutes the selection operation means and the display position movement operation means of the present invention, and is composed of an arbitrary input device such as an operation panel such as a keyboard, a mouse, a trackball, and a liquid crystal display (LCD). Is done.

  Further, the control unit 8 performs control for causing the display monitor 11 to display a distribution image of RI in the subject based on the collected projection data, estimated projection data, or reconstruction data. The control unit 8 can display a plurality of these projection data simultaneously. In particular, the collected projection data and the estimated projection data can be combined and displayed on the display monitor 11 by combining the coordinate values and the like. At this time, when the operator operates the operation unit 10, the control unit 8 can also control the display monitor 11 so as to move the display position of the collected projection data superimposed and displayed based on the operation signal. In addition, the control unit 8 performs control for causing the display monitor 11 to display various screens such as an operation screen and a test result screen of the nuclear medicine diagnosis apparatus 1. Here, the display monitor 11 constitutes display means according to the present invention, and is constituted by a display device such as an LCD or a CRT.

  Further, the control unit 8 determines an error calculation unit 8A that calculates an error between the collected projection data stored in the storage unit 9 and the estimated projection data, and whether or not the error is equal to or greater than a predetermined value. Data selection means 8B for selecting a pair of collected projection data and estimated projection data determined as described above, and out of the selected pair of collected projection data and estimated projection data, the collected projection data is matched with the estimated projection data. Data correction means 8C for correction. The error calculated by the error calculation means 8A is calculated, for example, regarding the variance or standard deviation value of the collected projection data and the estimated projection data as two-dimensional data. Further, a deviation square error between the collected projection data and the estimated projection data is obtained by the NMSE (Normalized Mean Square Error) method using the mathematical formula shown in [Equation 1] below, and the position where the value is minimized is obtained. It can also be estimated. As the correction process by the data correction unit 8C, a known method such as a least square method is used. The control unit 8 stores information on the correction amount of the collected projection data by the data correction unit 8C in the correction amount storage unit 9D of the storage unit 9. Further, the data correction unit 8C can perform rotation center correction as described later in the correction process. The control unit 8 constitutes the control means referred to in the present invention.

ｆ（ｘ、ｙ）は基準となる画像、ｇ（ｘ、ｙ）は処理に係る画像をそれぞれ表す。

f (x, y) represents a reference image, and g (x, y) represents an image related to processing.

  The data collection unit 4, preprocessing unit 5, reconstruction processing unit 6, estimated data creation unit 7, and control unit 8 perform the above-described operations when an arithmetic control unit such as a CPU executes a predetermined computer program. The storage unit 9 includes a storage device capable of writing / reading such as a hard disk drive (HDD), and includes a collected projection data storage unit 9A, an estimated projection data storage unit 9B, a reconstruction data storage unit 9C, and a correction amount. The storage unit 9D includes a directory set in the HDD or the like.

[Processing procedure by nuclear medicine diagnostic equipment]
An example of the procedure of body motion correction processing executed by the nuclear medicine diagnosis apparatus 1 of the present embodiment having the above-described configuration will be described. The flowchart of FIG. 2 shows the flow of the processing procedure by the nuclear medicine diagnostic apparatus 1.

  First, the detector 2, the position calculation unit 3, and the data collection unit 4 perform the same processing as that of a normal nuclear medicine examination (SPECT examination), detect the radiation emitted from the RI in the subject, and calculate the projection data. Collection is executed (S01). At this time, for example, 30 slices of projection data are collected for a region including the region of interest such as the heart and liver of the subject. The collected projection data (collected projection data) is associated with each slice and stored in the collected projection data storage unit 9A of the storage unit 9 (S02), and the preprocessing unit 5 performs the above preprocessing. It is transmitted to the reconstruction processing unit 6 (S03). The reconstruction processing unit 6 reconstructs the collected projection data subjected to the preprocessing, and creates reconstruction data for each slice (S04). At this time, attenuation correction is also performed.

  FIG. 3 is a diagram conceptually showing this reconstruction process. Reference numerals 100A, 100B, and 100C denote one slice of acquired projection data based on the radiation detected by the detectors 2A, 2B, and 2C, respectively, and reference numeral 200 denotes a three-dimensional inverse from the acquired projection data 100A, 100B, and 100C. The reconstruction data 200 created by a method such as a projection method is shown. Actually, the collected projection data 100A and the like are obtained as two-dimensional image data, and the reconstruction data is obtained as three-dimensional image data. In FIG. 3, for simplicity of illustration, one-dimensional data, It is represented by two-dimensional data (the same applies to FIG. 4 described later).

  As conceptually shown in FIG. 4, the estimation data creation unit 7 projects the reconstruction data 200 received from the reconstruction processing unit 6 in the same projection direction as the acquired projection data (addition, line integration, etc.). Estimated projection data 300A corresponding to the projection direction of the detector 2A, estimated projection data 300B corresponding to the projection direction of the detector 2B, and estimated projection data 300C corresponding to the projection direction of the detector 2C are created (S05). The estimated projection data 300A, 300B, and 300C are stored in the estimated projection data storage unit 9B by the control unit 8 (S06). The estimated data creation unit 7 executes the creation process for the reconstruction data of each slice.

  The control unit 8 reads the collected projection data and estimated projection data of each collected slice from the storage unit 9 and displays the corresponding pair of collected projection data and estimated projection data on the display monitor 11 (S07). ) The error calculation means 8A calculates an error such as a variance value for each pair of collected projection data and estimated projection data (S08). For example, as shown in FIG. 5, the collected projection data 100A (dotted line) and the estimated projection data 300A (solid line) corresponding to the projection direction of the detector 2A shown in FIGS. Here, reference numeral 101A represents a site of interest in the projection data 100A, and reference numeral 301A represents a site of interest in the projection data 300A. Similarly, the collected projection data 100B and the estimated projection data 300B, and the collected projection data 100C and the estimated projection data 300C are also displayed in a superimposed manner.

  The data selection unit 8B compares the error calculated by the error calculation unit 8A with a predetermined value set in advance and determines the size (S09). When it is determined that the error is smaller than the predetermined value for all the pairs of collected projection data and estimated projection data (S10; N), the control unit 8 obtains the reconstruction data based on the collected projection data as the inspection result, That is, the image is displayed on the display monitor 11 as an RI distribution image in the subject (S20).

  On the other hand, when there is a pair of the collected projection data and the estimated projection data having an error larger than the predetermined value (S10; Y), the data selection unit 8B selects the collected projection data and the estimated projection data to select the data correction unit 8C. (S11). Here, instead of selecting all of the collected projection data having a larger error than the predetermined value, some of them may be selected. Further, instead of automatically executing such a selection process, the operator may select a desired pair by operating the operation unit 10 (selection operation means). In that case, the error value may be displayed on the display monitor 11, and the operator may perform the selection process while referring to the error value. Further, in this selection process, a pair of acquired projection data and estimated projection data of a plurality of slices can be selected.

  The pair of acquired projection data and estimated projection data selected in step S11 corresponds to a slice having a large data position shift (error). Therefore, by appropriately setting the predetermined value, it can be estimated that the slice including the pair is an examination result of a part having an error due to body movement of the subject.

  The data correction unit 8C sequentially calculates an error from the estimated projection data while moving the collected projection data two-dimensionally (up and down, left and right) out of the pair of the collected projection data and the estimated projection data selected by the data selection unit 8B. The correction processing is performed by determining the position of the collected projection data that is obtained and minimizes the error (S12). For example, when the collected projection data 100A and the estimated projection data 300A shown in FIG. 5 are corrected, an error from the estimated projection data 300A is sequentially calculated while the collected projection data 100A displayed in a dotted line is moved two-dimensionally. The position of the collected projection data that minimizes the value is determined. Instead of determining the “minimum error” position, an allowable error value is set in advance, and the position of the collected projection data is determined so that the error is smaller than the set value of the error. Also good. Here, the data correction means 8C can also perform rotation center correction as described later on the collected projection data subjected to error correction.

  The control unit 8 stores the movement amount of the collected projection data after correction in step S12, that is, the correction amount, in the correction amount storage unit 9D of the storage unit 9 in association with the collected projection data (S13), and after the correction. The collected projection data and the estimated projection data are displayed superimposed on the display monitor 11 (S14). Here, the corrected error value may be displayed together.

  When the operator determines that further correction is necessary by looking at the corrected collected projection data and the estimated projection data displayed in a superimposed manner, the operator operates the operation unit 10 (display position moving operation means) to estimate the collected projection data. By moving up, down, left, and right so as to match the projection data, correction can be performed by manually adjusting the error (S15).

  The control unit 8 transmits the corrected collected projection data to the reconstruction processing unit 6. The reconstruction processing unit 6 reconstructs the corrected collected projection data to create new reconstruction data (S04). The estimated data creating unit 7 creates new estimated projection data by the same method as described above based on the new reconstruction data (S05).

  The control unit 8 causes the pair of new estimated projection data and original collected projection data to be displayed on the display monitor 11 (S07) and calculates an error such as a variance value for the pair by the error calculation unit 8A. (S08). The data selection unit 8B compares this error with the predetermined value and determines the magnitude (S09).

  The data correction unit 8C performs a correction process on a pair of newly estimated projection data and the original collected projection data determined to have an error larger than the predetermined amount (S12). At this time, the data correction unit 8C calls the correction amount stored in the correction amount storage unit 9D in step S13, moves the original collected projection data by the correction amount, and executes the current correction process. Then, the sum of the previous and current correction amounts (movement amounts) of the original collected projection data is calculated and stored in the correction amount storage unit 9C (S13). In the third and subsequent correction processes, the data correction unit 8C executes the correction process based on the total correction amount up to the previous time, and stores the total correction amount up to this time in the correction amount storage unit 9C.

  The above processing is repeated until “N” is determined in step S10, and an RI distribution image based on the reconstruction data at that time is displayed on the display monitor 11 (S20). Above, the body movement correction process by the nuclear medicine diagnostic apparatus 1 of this embodiment is complete | finished. The nuclear medicine diagnosis apparatus 1 is configured to sequentially correct the original collected projection data by such processing.

[Function and effect]
According to the nuclear medicine diagnosis apparatus 1, three-dimensional reconstruction data is created for the collected projection data of each collected slice, and the reconstruction data is projected to create two-dimensional estimated projection data. It is possible to perform two-dimensional correction so that the deviation (error) of the position of the original collected projection data with respect to the estimated projection data becomes small. This error can be estimated to be caused by the body movement of the subject as described above. Since the correction processing is selectively performed on slices having a large error, the correction processing can be executed in the slice arrangement direction, that is, the body axis direction. In addition, correction in the slice plane direction of each selected slice, that is, the direction orthogonal to the body axis can also be executed.

  Further, according to the nuclear medicine diagnostic apparatus 1, new corrected data is created by reconstructing the collected projection data once corrected, and new estimated projection data is created by projecting the new reconstructed data. Then, the correction for further reducing the error between the new estimated projection data and the original collected projection data is sequentially executed. Therefore, the correction can be repeated until the error becomes sufficiently small, and highly accurate body movement correction can be performed.

  Further, since the correction process is configured to be automatically executed (see step S12), the body movement correction is preferably performed even when the image of the site of interest such as the heart or the liver is not clearly displayed. Can be executed.

  Further, by displaying the error calculated by the error calculation means 8A on the display monitor 11, manual correction by the operator himself can be supported, and high accuracy of body motion correction can be achieved.

[Rotation center correction]
The rotation center correction that can be performed by the nuclear medicine diagnosis apparatus 1 according to the present invention will be described. This rotation center correction is a correction process that improves the accuracy of the body motion correction described above and improves the accuracy of the nuclear medicine examination.

  The error correction process in step S12 of the flowchart of FIG. 2 is performed by moving the collected projection data two-dimensionally so as to match the estimated projection data. Therefore, the rotation center correction amount measured at the time of periodic inspection or the like, that is, the rotation center correction amount in the preprocessing (step S03) is Δx0, Δy0 (rotation center correction is a two-dimensional on the incident surface of the detector 2). The data correction unit 8C sets the two-dimensional error correction amounts ΔX1 and ΔY1 for the collected projection data to Δx0−ΔX1 = Δx1, Δy0− in the first data correction in the sequential correction. Change to ΔY1 = Δy1. Thereby, the correction amounts Δx1 and Δy1 of the rotation center in consideration of the correction amount in the first error correction are acquired.

  The same rotation center correction can be sequentially executed during the second and subsequent data corrections. That is, assuming that the correction amounts in the (N−1) th error correction are Δx (N−1) and Δy (N−1) (N ≧ 2), the data correction means 8C has the Nth error correction ΔXN and ΔYN. Are changed to Δx (N−1) −ΔXN = ΔxN and Δy (N−1) −ΔYN = ΔyN. As a result, the rotation center correction amounts ΔxN and ΔyN in consideration of the correction amount in the Nth error correction are acquired.

  By performing such rotation center correction, rotation center correction can be performed as appropriate even when body movement of the subject occurs during the examination, and the accuracy of the body movement correction processing according to the present invention can be improved. Further improvement can be achieved.

  The above-described details are merely an example of a configuration for carrying out the present invention, and therefore various modifications can naturally be made within the scope of the gist of the present invention.

It is a block diagram which shows an example of schematic structure of embodiment of the nuclear medicine diagnostic apparatus which concerns on this invention. It is a flowchart which shows an example of the process sequence performed by embodiment of the nuclear medicine diagnostic apparatus which concerns on this invention. It is the schematic for demonstrating an example of the process sequence performed by embodiment of the nuclear medicine diagnostic apparatus which concerns on this invention. It is the schematic for demonstrating an example of the process sequence performed by embodiment of the nuclear medicine diagnostic apparatus which concerns on this invention. It is the schematic for demonstrating an example of the process sequence performed by embodiment of the nuclear medicine diagnostic apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nuclear medicine diagnostic apparatus 2A, 2B, 2C Detector 3 Position calculation part 4 Data collection part 5 Preprocessing part 5A Scattering ray correction means 5B Rotation center correction means 5C Uniformity correction means 6 Reconstruction processing part 6A Attenuation correction means 7 Estimation Data creation unit 8 Control unit 8A Error calculation unit 8B Data selection unit 8C Data correction unit 9 Storage unit 9A Collected projection data storage unit 9B Estimated projection data storage unit 9C Reconstruction data storage unit 10 Operation unit 11 Display monitors 100A, 100B, 100C Collected projection data 200 Reconstructed data 300A, 300B, 300C Estimated projection data

Claims (6)

Data collection means for detecting radiation emitted from a radioisotope administered into a subject and collecting two-dimensional projection data;
Reconstruction processing means for correcting the influence of attenuation of the radiation when propagating in the subject with respect to the collected projection data and generating three-dimensional reconstruction data based on the corrected projection data When,
A nuclear medicine diagnostic apparatus for displaying a distribution image of the radioisotope in the subject based on the generated reconstruction data on a display means,
Estimated data creation means for projecting the reconstruction data obtained by the reconstruction processing means in the same direction as the projection data to create two-dimensional estimated projection data;
An error calculating means for calculating an error between the generated estimated projection data and the projection data;
Data correction means for correcting the position of the projection data so that the calculated error is minimized;
The reconstruction processing means reconstructs the projection data whose position has been corrected to create new reconstruction data,
The estimated data creation means creates new estimated projection data based on the new reconstruction data created by the reconstruction processing means,
The error calculation means calculates an error between the new estimated projection data and the collected projection data,
The data correction unit corrects the position of the collected projection data so that the error with respect to the new estimated projection data is small, thereby correcting the correction amount thus corrected with respect to the collected projection data. Perform sequential correction to correct with the sum,
The nuclear medicine diagnostic apparatus, wherein the display means displays a distribution image of the radioisotope based on new reconstructed data corrected sequentially . 2. The nuclear medicine diagnosis apparatus according to claim 1, further comprising control means for controlling the data correction means so as to make the error smaller than a predetermined value . further,
Each time the error calculation means calculates the error, it is determined whether the error does not exceed a predetermined value, and the data correction means performs correction until the error does not exceed the predetermined value, and the reconstruction processing means A controller that repeats the generation of reconstruction data, the creation of estimated projection data by the estimated data creating means, the error calculation by the error calculating means, and the determination;
The display means, nuclear medicine diagnostic apparatus according to claim 1, wherein the error is characterized that you display the distribution image of the radioisotope based on reconstructed data when not exceeding a predetermined value. Further comprising data selection means for selecting a pair of the estimated projection data and the collected projection data in which the error calculated by the error calculation means is a predetermined value or more,
4. The projection data corrected by the data correction unit is the collected projection data of the pair selected by the data selection unit. 5. Nuclear medicine diagnostic equipment. The display means superimposes and displays the collected projection data and the estimated projection data,
A selection operation means for manually selecting the desired pair from the superimposed projection data and the estimated projection data;
4. The projection data corrected by the data correction unit is the collected projection data of the pair selected by the selection operation unit. 5. Nuclear medicine diagnostic equipment. The display means superimposes and displays the projection data corrected by the data correction means and the estimated projection data created by the estimated data creation means,
A display position moving operation means for manually moving the projection data displayed in superposition so as to match the display position of the estimated projection data;
The reconstruction unit reconstructs the projection data in which an error from the estimated projection data is adjusted by the movement by the display position movement operation unit, and creates new reconstruction data, and the display unit includes: 6. The nuclear medicine diagnosis apparatus according to claim 1, wherein a distribution image of the radioisotope based on the new reconstruction data is displayed.

Images