JP2017142131A - Nuclear medicine diagnosis device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nuclear medicine diagnosis device capable of improving an accuracy of correction using an attenuation map.SOLUTION: A nuclear medicine diagnosis device includes: a storage part; a positioning part; an elimination part; an image data generation part; an attenuation map data generation part; and a reconstruction part. The positioning part positions an image expressed by a first mode image data to an image expressed by a second mode image data expressing an area of a second support tool used in an area projecting an analyte and a X ray CT device. The elimination part eliminates the area expressing the second support tool from the image expressed by the second mode image data. The image data generation part allots a pixel value of the first mode image data after the positioning to the pixel of the image expressing the second mode image data after the elimination so as to generate synthesized image data. The attenuation map data generation part generates an attenuation map data from the synthesized image data generated by the image data generation part.SELECTED DRAWING: Figure 3

Description

  Embodiments described herein relate generally to a nuclear medicine diagnostic apparatus.

  A nuclear medicine diagnostic apparatus uses a property that a medicine (blood flow marker, tracer) containing a radioisotope (hereinafter referred to as RI) is selectively taken into a specific tissue and organ in the living body, The gamma rays emitted from the distributed RI are detected by a gamma ray detector disposed outside the living body. The detection result of gamma rays is used for generating a nuclear medicine image by imaging a dose distribution of gamma rays and diagnosing a function of a body organ or the like.

  Gamma rays are emitted from RI distributed in the living body and then attenuated in the living body until they are detected by a gamma ray detector disposed outside the living body. For this reason, the detection result of gamma rays includes the influence of attenuation in the living body. A method often used as a method of correcting the influence of attenuation in this kind of living body is a method of correcting the detection result of gamma rays based on an attenuation coefficient map indicating a distribution of attenuation coefficients of gamma ray energy of the nuclide used. . At this time, as an attenuation map creation method, for example, there is a method of creating an attenuation map using anatomical form information acquired by an X-ray CT apparatus or the like.

  Since the resolution of a conventional nuclear medicine image is not sufficient, even after correction using an attenuation map created using an X-ray CT image, the corrected nuclear medicine image contains an error of about 10%. It was. Therefore, the attenuation map can be displayed without considering the difference between, for example, the top plate and headrest provided in the X-ray CT apparatus included in the X-ray CT image, and the top plate and headrest provided in the nuclear medicine diagnostic device included in the nuclear medicine image. Even if it was created, the effect on the accuracy of image diagnosis due to the difference between the top plate and the headrest included in the corrected nuclear medicine image was assumed to be within the error range.

  In a nuclear medicine diagnosis apparatus such as a three-detector SPECT apparatus, which has been widely used in recent years, the resolution of the generated nuclear medicine image is compared with the resolution of the nuclear medicine image generated by the conventional nuclear medicine diagnosis apparatus. Greatly improved. When such a nuclear medicine diagnostic apparatus is used, the attenuation created without considering the difference between the top board and headrest provided in the X-ray CT apparatus and the top board and headrest provided in the nuclear medicine diagnostic apparatus as before. There is an opinion that it is difficult to carry out image diagnosis with the expected accuracy by correction using a map.

Special table 2011-522275 gazette

  An object of the embodiment is to provide a nuclear medicine diagnostic apparatus that can improve the accuracy of correction using an attenuation map.

  According to the embodiment, the nuclear medicine diagnosis apparatus includes a storage unit, an alignment unit, a deletion unit, an image data generation unit, an attenuation map data generation unit, and a reconstruction unit. A memory | storage part memorize | stores the 1st form image data showing the area | region of the 1st support instrument used with a nuclear medicine diagnostic apparatus. The alignment unit is configured such that the first morphological image data is compared with an image represented by the second morphological image data representing the region on which the subject is projected and the region of the second support instrument used in the X-ray CT apparatus. Align the image that you want to represent. The deletion unit deletes an area representing the second support device from the image represented by the second morphological image data. The image data generation unit assigns a pixel value of the first morphological image data after the alignment to a pixel represented by the second morphological image data after the deletion, and generates third image data. The attenuation map data generation unit generates attenuation map data from the third image data generated by the image data generation unit. The reconstruction unit reconstructs nuclear medicine projection data relating to the subject based on the generated attenuation map data.

FIG. 1 is a diagram illustrating a configuration of a SPECT apparatus according to the first embodiment. FIG. 2 is an example of headrest shape data included in the database according to the first embodiment. FIG. 2A is a diagram illustrating the contents of first and second X-ray CT image data used in the first embodiment. FIG. 3 is a flowchart showing a flow of image processing according to the first embodiment. FIG. 4 is a diagram illustrating an example of a flow of deleting the headrest image for the X-ray CT apparatus from the CT image and adding the headrest image for the SPECT apparatus in the image processing according to the first embodiment. . FIG. 5 is a diagram illustrating a configuration of a SPECT apparatus according to the second embodiment. FIG. 5A is a diagram illustrating the contents of first and second X-ray CT image data used in the second embodiment. FIG. 6 is a flowchart showing a flow of image processing according to the second embodiment. FIG. 7 is a diagram illustrating a configuration of a SPECT apparatus according to the third embodiment. FIG. 7A is a diagram for explaining the contents of the first and second attenuation map data used in the third embodiment. FIG. 8 is a flowchart showing a flow of image processing according to the third embodiment. FIG. 9 is a diagram illustrating an example of a sagittal image of the first SPECT image that is a three-dimensional image. FIG. 10 is a diagram illustrating an example of a transverse image of the first SPECT image that is a three-dimensional image. It is a figure showing the structure of the reconfiguration | reconstruction circuit in other embodiment. FIG. 12 is an example of a schematic diagram illustrating an example of a headrest used in the SPECT apparatus. FIG. 13 is an example of a schematic diagram illustrating an example of a headrest used in an X-ray CT apparatus.

  Hereinafter, a nuclear medicine diagnosis apparatus according to the present embodiment will be described with reference to the drawings.

  In order to specifically describe the embodiment, it is assumed that the nuclear medicine diagnostic apparatus according to the present embodiment is a SPECT apparatus that performs SPECT collection. The nuclear medicine diagnostic apparatus may be a PET apparatus that performs PET collection.

[First Embodiment]
FIG. 1 is a diagram illustrating a configuration example of a SPECT apparatus 1 which is an example of a nuclear medicine diagnosis apparatus according to the present embodiment. The SPECT apparatus 1 includes a gantry 11, a top plate 13, a headrest 15, a drive circuit 17, an imaging control circuit 19, gamma cameras 20-1, 20-2, and 20-3, a data collection circuit 23, a storage circuit 25, and a preprocessing circuit. 27, a processing circuit 29, a display circuit 31, an input interface circuit 33, and a system control circuit 35.

  The gantry 11 supports an annular or disk-shaped rotating frame 12 so as to be rotatable around the rotation axis Z.

  The rotating frame 12 includes at least one of gamma cameras 20-1, 20-2, and 20-3, which will be described later, so as to surround the rotation axis Z that is the center of the opening. That is, the rotary frame 12 is a support mechanism that supports a plurality of gamma cameras so as to be rotatable about the rotation axis Z. Any number of gamma cameras may be included in the rotary frame 12 in the present embodiment, but it is assumed that the number of gamma cameras is three for the sake of specific description.

  The top plate 13 is for placing the subject (patient) P. The top plate 13 is disposed at the opening of the rotating frame 12. The top 13 is positioned so that the center of the imaging region of the subject P coincides with the center of the FOV (field of view) in the opening, that is, the rotation axis Z.

  The headrest 15 is used to support the head when photographing the head of the subject P. The headrest 15 is usually attached to the tip of the top plate 13 in many cases.

  The drive circuit 17 has a gear and a motor (not shown). The drive circuit 17 rotates the rotating frame 12 around the rotation axis Z according to control by an imaging control circuit 19 described later. When the rotary frame 12 rotates around the rotation axis Z, the gamma cameras 20-1, 20-2 and 20-3 rotate around the rotation axis Z. The drive circuit 17 moves the gamma cameras 20-1, 20-2 and 20-3 in a direction toward the subject P and in a direction away from the subject P according to control by the imaging control circuit 19. That is, the drive circuit 17 moves the gamma cameras 20-1, 20-2, and 20-3 in a direction orthogonal to the rotation direction (tangential direction of the rotation movement).

  The drive circuit 17 moves the top plate 13 up and down along the direction of the gravity axis according to control by an imaging control circuit 19 described later. The drive circuit 17 moves the top board 13 along the body axis O (rotation axis Z) direction of the subject P on the imaging region of the opening in the central portion of the rotation frame 12 according to the control by the imaging control circuit 19. .

  The gamma camera 20-1 detects gamma rays of single photons emitted from a single photon emission nuclide (RI) administered to the subject P. The gamma camera 20-1 includes a gamma ray detector 21-1 and a signal processing circuit 22-1.

  The gamma ray detector 21-1 has a scintillator provided with a collimator and a plurality of photoelectric conversion elements arranged two-dimensionally. The gamma rays collimated by the collimator are converted into light by a scintillator and converted into an electric signal by a photoelectric conversion element. Examples of the photoelectric conversion element include a photomultiplier tube and a photodiode. Note that the gamma ray detector 21-1 can also be configured using a direct conversion type semiconductor element or the like. The gamma ray detector 21-1 supplies the electric signal generated in the detection element to the signal processing circuit 22-1.

  Each time a gamma ray enters the gamma ray detector 21-1, the signal processing circuit 22-1 is based on the output value of the electrical signal from the gamma ray detector 21-1 and the position coordinates of the detection element, and the incident position of the incident gamma ray. Calculate the coordinates. The signal processing circuit 22-1 calculates the energy value of the incident gamma ray based on the output value of the electric signal every time the gamma ray enters the gamma ray detector 21-1. Further, the signal processing circuit 22-1 transmits a combination of a signal representing the incident position coordinates for each incident gamma ray and a signal representing the energy value to the data collecting circuit 23 as a gamma ray detection signal.

  Note that the imaging timing of the gamma camera 20-1 is controlled by the imaging control circuit 19.

  The gamma cameras 20-2 and 20-3 have the same configuration and function as the gamma camera 20-1.

  The angle around the rotation axis Z of the gamma cameras 20-1, 20-2, and 20-3 is called a projection angle. For example, when the center of the detection surface of the gamma camera 20-1 is at the highest position, the projection angle is 0 degree, and when it is at the lowest position, the projection angle is 180 degrees. In FIG. 1, the projection angle interval of the three gamma cameras 20-1, 20-2 and 20-3 is 120 °, but the projection angle interval according to the present embodiment is not limited to this.

  The imaging control circuit 19 supplies control signals to the drive circuit 17, the gamma cameras 20-1, 20-2, and 20-3 and the data collection circuit 23 described later according to the imaging parameters, and releases them from the RI in the subject P. A processor that collects SPECT acquired gamma rays. Imaging parameters include, for example, acquisition time, image matrix size, number of angular samplings, energy window, and the like. The imaging parameters are set based on predetermined information stored in advance in the storage circuit 25, for example. Further, the imaging parameters may be set by the user via the input interface circuit 33, for example.

  The data collection circuit 23 is a processor that generates projection data based on the gamma ray detection signals received from the gamma cameras 20-1, 20-2, and 20-3. The data collection circuit 23 receives gamma ray detection signals from the gamma cameras 20-1, 20-2 and 20-3 by a predetermined data collection method. The predetermined data collection method includes a frame mode method and a list mode method. The data collection circuit 23 generates data indicating the spatial distribution of the count value (hereinafter referred to as projection data) based on the received gamma ray detection signal in accordance with the control signal supplied from the imaging control circuit 19.

  In the case of the frame mode method, the data collection circuit 23 performs a pulse height discrimination process on the gamma ray detection signals supplied from the signal processing circuits 22-1, 22-2, and 22-3. In the wave height discrimination process, the data collection circuit 23 extracts a gamma ray detection signal having a signal representing an energy value belonging to a predetermined energy window from the gamma ray detection signal. The data collection circuit 23 counts gamma ray detection signals corresponding to energy values within a predetermined energy window. The predetermined energy window is set to various energy ranges depending on purposes. The data collection circuit 23 records the count value of the gamma ray signal in the projection angle unit at the memory address corresponding to each incident position coordinate. As described above, the data collection circuit 23 generates projection data by repeating counting in units of projection angles. The generated projection data is stored in the storage circuit 25.

  In the case of the list mode method, the data collection circuit 23 stores the gamma ray detection signal in the storage circuit 25 in a list format in time series. The gamma ray detection signal stored in the list format is called histogram data. The histogram data includes the incident position coordinates, the energy value, the projection angle of the gamma cameras 20-1, 20-2 and 20-3, and the gamma rays of the gamma cameras 20-1, 20-2 and 20-3. Data associated with detection time. The data collection circuit 23 generates projection data from the histogram data by performing a pulse height discrimination process on the histogram data. The generated projection data is stored in the storage circuit 25.

  The storage circuit 25 includes a recording medium readable by a processor, such as a magnetic or optical recording medium or a semiconductor memory. The storage circuit 25 stores a program executed by the circuit of the SPECT apparatus 1 according to this embodiment. Note that some or all of the programs and data in the storage medium of the storage circuit 25 may be downloaded via an electronic network.

  The storage circuit 25 stores the projection data generated by the data collection circuit 23. The storage circuit 25 outputs the stored projection data to the preprocessing circuit 27 under the control of the system control circuit 35.

  Further, the storage circuit 25 stores preprocessing condition information for the preprocessing circuit 27 described later to perform preprocessing. The storage circuit 25 outputs the stored preprocessing condition information to the preprocessing circuit 27 under the control of the system control circuit 35.

  In addition, the storage circuit 25 stores a database related to the support device and the like. The support instrument refers to at least one of a top plate and a headrest used in, for example, an X-ray CT apparatus or a SPECT apparatus. The database related to the support device or the like is, for example, image data acquired by imaging the support device or the like used in the SPECT device 1 or the like using an X-ray CT apparatus (hereinafter referred to as first X-ray CT image data). ) And incidental information of image data as a single logical record.

  The first X-ray CT image data may be either one or a plurality of two-dimensional image data. Further, the first X-ray CT image data may be three-dimensional image data.

  Further, the incidental information of the image data is patient information and examination information. The conditions for identifying the support device, the model number of the apparatus, and a predetermined identification code (for example, such that the SPECT apparatus and the CT apparatus can be distinguished) are included in the conditions therein.

  Further, the storage circuit 25 uses an X-ray CT apparatus to obtain X-ray CT image data (hereinafter referred to as second X-ray) including a support instrument acquired by imaging the subject P while being supported by the support instrument. (Referred to as CT image data).

  The second X-ray CT image data may be either one or a plurality of two-dimensional image data. Further, the second X-ray CT image data may be three-dimensional image data.

  In addition, the storage circuit 25 stores first SPECT image data generated by a processing circuit 29 described later.

  An example of the image data of the headrest for the SPECT device 1 included in the database is shown in FIG. FIG. 2 shows a case where the image data of the headrests of the SPECT apparatuses A, B and C are stored in the storage circuit 25, for example. Note that when the image data of the headrest is three-dimensional image data, FIG. 2 corresponds to the cross-sectional image data of the three-dimensional image.

  Further, the database may include image data obtained by converting the statistical data into a numerical image of the shape of the support device used in the SPECT apparatus and the PET apparatus.

  The preprocessing circuit 27 is a processor that performs various correction processes on the projection data before generating a reconstructed image, for example. The preprocessing circuit 27 acquires projection data stored in the storage circuit 25. The preprocessing circuit 27 performs uniformity correction, rotation center correction on projection data according to preprocessing condition information stored in the storage circuit 25 in advance or preprocessing condition information input by the user via the input interface circuit 33. Correction processing such as preprocessing filtering processing (for example, Butterworth) is executed.

  The display circuit 31 includes a general display output device such as a liquid crystal display or an OLED (Organic Light Emitting Diode) display. The display circuit 31 controls the first X-ray CT image data and the second X-ray CT image data, differential image data, composite image data, first SPECT image data, and second Based on the SPECT image data and the attenuation map data, the first X-ray CT image and the second X-ray CT image, the difference image, the synthesized image, the first SPECT image, the second SPECT image, and the attenuation map described later are used. Is displayed.

  The input interface circuit 33 is realized by, for example, a trackball, a switch button, a mouse, a keyboard, a touch pad that performs an input operation by touching an operation surface, and a touch panel display in which a display screen and a touch pad are integrated. The input interface circuit 33 outputs an operation input signal corresponding to a user operation to the system control circuit 35. In the present embodiment, the input interface circuit is not limited to one having physical operation components such as a mouse and a keyboard. For example, an example of the input interface circuit includes an electric signal processing circuit that receives an electric signal corresponding to an input operation from an external input device provided separately from the apparatus and outputs the electric signal to the system control circuit 35. It is.

  The processing circuit 29 generates attenuation map data in consideration of the difference between the support instrument used in the X-ray CT apparatus and the support instrument used in the nuclear medicine diagnostic apparatus, and the nuclear medicine image data to which the created attenuation map data is applied. Is a processor that generates FIG. 2A is a diagram illustrating the contents of first and second X-ray CT image data used in the first embodiment. As shown in FIG. 2A, the first X-ray image data represents a support instrument used in the SPECT apparatus 1, while the second X-ray CT image data is obtained from the subject P and the X-ray CT apparatus. Represents the support device used. The processing circuit 29 deletes an area representing the support instrument used in the X-ray CT apparatus included in the second X-ray CT image data from the area represented by the second X-ray CT image data. The processing circuit 29 generates attenuation map data in consideration of the difference between the support devices by adding the support device region represented by the first X-ray CT image data to the deleted region.

  The processing circuit 29 calls each operation program from the storage circuit 25 and executes the called program to thereby execute the first reconstruction function 291, the image creation function 292, the attenuation map creation function 293, and the second reconstruction function 294. Realize.

  The first reconstruction function 291 generates a SPECT image (hereinafter referred to as first SPECT image data) based on the projection data preprocessed by the preprocessing circuit 27 without correction using the attenuation map. It is a function. Specifically, in the first reconstruction function 291, the processing circuit 29 obtains a density distribution of a predetermined tomographic plane by back projecting the projection data. As a back projection method, there are a conventional method such as an FBP (filtered back projection) method, a Fourier transform method and the like. The processing circuit 29 stores the generated first SPECT image data in the storage circuit 25.

  The image creation function 292 deletes the area representing the support instrument used in the X-ray CT apparatus included in the second X-ray CT image data from the second X-ray CT image data, This is a function for creating a composite image obtained by adding pixel values of one X-ray CT image data.

  Hereinafter, an example of processing realized by the image creation function 292 is data of only the headrest in which the support device represented on the first X-ray CT image does not include the top plate, and on the second X-ray CT image. The description will be given assuming that the support device represented is data of only the headrest not including the top plate.

  First, the processing circuit 29 acquires, for example, the second X-ray CT image data selected by the user from the storage circuit 25. Further, the processing circuit 29 compares the model number of the SPECT apparatus 1 with the model number included in the incidental information of the plurality of first X-ray CT image data stored in the storage circuit 25, and corresponds to the record corresponding to the model number. 1 X-ray image data is read from the storage circuit 25.

  The processing circuit 29 displays a superimposed image obtained by superimposing the first X-ray CT image on the second X-ray CT image on the display circuit 31. The user visually adjusts the position so that the area representing the headrest included in the second X-ray CT image data is included in the area of the headrest represented by the first X-ray CT image data via the input interface circuit 33. The processing circuit 29 performs system control using, as first related information, related information indicating to which pixel on the second X-ray CT image each pixel value included in the first X-ray CT image data is assigned. Obtained via the circuit 35.

  For example, based on the first related information, the processing circuit 29 has the same pixel size and image matrix size as the second X-ray CT image data, and on the image represented by the image data in which the pixel values of all the pixels are zero. Mask image data in which the pixel value of the first X-ray CT image data is assigned to the pixel is generated.

  The processing circuit 29 subtracts the mask image data from the second X-ray CT image data, and deletes the region representing the headrest from the second X-ray CT image. Hereinafter, the image data including the subject P and from which the region representing the headrest used in the subject X-ray CT apparatus is deleted is referred to as difference image data.

  The processing circuit 29 creates composite image data by assigning the pixel values of the first X-ray CT image data to the pixels on the difference image based on the first related information in the difference image data. In addition, in order to more accurately assign the pixel value of the first X-ray CT image data to the difference image data, the user uses the first SPECT image displayed on the display circuit 31 and the difference image data. The allocation position may be determined via the input interface circuit 33 while viewing the fusion image.

  In addition, although the case where difference image data is created using mask image data has been described as an example, the present invention is not limited to this. For example, the difference image data may be generated by extracting the outline by performing a segmentation process such as performing a threshold process on each pixel in the region representing the headrest included in the second X-ray CT image data.

  The attenuation map creation function 293 calculates the pixel value of the region representing the subject P included in the composite image data created by the image creation function 292 and the pixel value of the region representing the support device used in the SPECT apparatus 1 from the CT value attenuation function. It is a function that generates attenuation map data by numerical conversion. The CT value attenuation coefficient value conversion is a process of converting a CT value (HU value) for each pixel of the X-ray CT image into an attenuation coefficient μ in order to generate attenuation map data. Various conventional CT value attenuation coefficient value conversion methods are known, and any of these can be used.

  The second reconstruction function 294 applies the attenuation map data created by the attenuation map creation function 293 to the first SPECT image data generated by the first reconstruction function 291, for example, and performs attenuation correction. This is a function for generating SPECT reconstructed image data (hereinafter referred to as second SPECT image data).

  The processing circuit 29 uses, for example, a rigid transformation or affine transformation, which is a registration technique, so that the predetermined specific points on the first SPECT image coincide with the predetermined specific points on the first image. Adjust the position. Thus, the processing circuit 29 multiplies each attenuation coefficient value μ included in the attenuation map data created by the attenuation map creation function 293 to any position in the region represented by the projection data that is the basis of the first SPECT image data. The related information indicating that is acquired through the system control circuit 35 as the second related information. The predetermined specific point is a point determined by, for example, converting the first SPECT image or the difference image into a binary image and obtaining the center of gravity.

  Further, the processing circuit 29 performs reconstruction with attenuation correction on the projection data that is the basis of the first SPECT image data based on the second related information by using attenuation map data. As a result, the processing circuit 29 generates second SPECT image data.

  The system control circuit 35 is a processor that controls each component circuit of the SPECT apparatus 1, for example. The system control circuit 35 functions as the center of the SPECT apparatus 1. The system control circuit 35 receives a user operation input signal via the input interface circuit 33, for example. The system control circuit 35 controls the operation of each function of the processing circuit 29 based on, for example, a user operation input signal. The system control circuit 35 displays a first X-ray CT image, a second X-ray CT image, a difference image, a composite image, a first SPECT image, a second SPECT image, an attenuation map, and the like on the display circuit 31. .

  Next, with respect to the operation of the first embodiment, the support device represented on the first X-ray CT image is only the headrest that does not include the top plate, and the support represented on the second X-ray CT image. A description will be given assuming that the device is only a headrest that does not include a top plate. FIG. 3 is an example of a flowchart of processing performed by various functions of the processing circuit 29. FIG. 4 shows the image processing according to the first embodiment. In the image processing according to the first embodiment, the headrest image for the X-ray CT apparatus is deleted from the X-ray CT image obtained by photographing the subject P. It is an example of the figure which shows the flow which adds the X-ray CT image of the headrest used. Hereinafter, the flow of the SPECT image reconstruction process will be described with reference to the example of the flowchart shown in FIG. 3 and FIG.

  First, the processing circuit 29 displays a superimposed image in which the first X-ray CT image is superimposed on the second X-ray CT image on the display circuit 31. The user visually adjusts the position through the input interface circuit 33 so that the area of the headrest represented by the first X-ray CT image data includes the area representing the headrest included in the second X-ray CT image data. The processing circuit 29 receives, via the system control circuit 35, first related information indicating which pixel value on the second X-ray CT image is assigned to each pixel value included in the first X-ray CT image data. (Step SA1). The left diagram in FIG. 4 is an example of a second X-ray CT image represented by the second X-ray CT image data.

  Based on the first related information, the processing circuit 29 has the same pixel size and image matrix size as the second X-ray CT image data, and the pixels on the image represented by the image data in which the pixel values of all the pixels are 0 The mask image data to which the pixel values of the first X-ray CT image data are assigned is generated (step SA2).

  The processing circuit 29 subtracts the pixel value of the mask image data from the pixel value of the second X-ray CT image data. Thereby, the processing circuit 29 deletes the area representing the headrest of the X-ray CT apparatus from the second X-ray CT image (step SA3). Hereinafter, the image data obtained as a result of the deletion is referred to as difference image data. The center diagram of FIG. 4 is an example of the difference image represented by the difference image data.

  Next, the processing circuit 29 uses a registration method, such as rigid body transformation or affine transformation, so that the predetermined specific point on the first SPECT image matches the predetermined specific point on the difference image. Align both images so that The processing circuit 29 indicates which position in the region represented by the projection data that is the basis of the first SPECT image data is to be multiplied by each attenuation coefficient value μ included in the attenuation map data generated in step SA6 described later. Second related information is acquired (step SA4).

  Thereafter, the processing circuit 29 creates composite image data by assigning the pixel value of the first X-ray CT image data to the pixels on the difference image based on the first related information (step SA5).

  Further, the processing circuit 29 attenuates the pixel value of the region representing the subject P and the pixel value of the region representing the support device included in the composite image data created in step SA5 by performing CT value attenuation coefficient value conversion. Map data is generated (step SA6).

  Finally, the processing circuit 29 uses, for example, the first SPECT image data as the initial image data, and uses the generated attenuation map data, the second related information, and the projection data that is the basis of the first SPECT image data, Reconstruction is performed by the successive approximation method with attenuation correction. As a result, the processing circuit 29 generates second SPECT image data (step SA7). The right diagram of FIG. 4 is an example of a reconstructed image subjected to attenuation correction, that is, a second SPECT image represented by the second SPECT image data.

  According to the first embodiment, the processing circuit 29 deletes an area representing a support instrument from the X-ray CT image (second X-ray CT image) of the subject P imaged by the X-ray CT apparatus, and the difference Generate image data. The processing circuit 29 applies an X-ray CT image (first X-ray CT image) representing a support instrument used in the SPECT apparatus 1 stored in the storage circuit 25 to an area where the area representing the support instrument is deleted from the difference image. ) Is added to generate composite image data. The processing circuit 29 performs reconstruction with attenuation correction using the generated attenuation map data, the second related information, and projection data that is the basis of the first SPECT image data, and converts the second SPECT image data into the second SPECT image data. Generate.

  The support instrument used in the SPECT apparatus and the support instrument used in the X-ray CT apparatus may have different shapes as shown in FIGS. In addition, the support instrument used in the SPECT apparatus may be different in material from the support instrument used in the X-ray CT apparatus. According to the SPECT apparatus 1 according to the present embodiment, at least one of the shape and material of the support instrument used in the SPECT apparatus and the support instrument used in the X-ray CT apparatus for imaging the subject P is different. Even so, it is possible to correct the first SPECT image data using the attenuation map data in consideration of the difference in the support device.

  Therefore, according to the SPECT apparatus 1 according to the present embodiment, the accuracy of correction using the attenuation map can be improved.

  Further, by improving the accuracy of correction using the attenuation map, it is expected that a semi-quantitative value such as SUV (Standardized Uptake value) of the PET image is obtained for the SPECT image after correction. If a quantitative value is obtained, accurate image diagnosis can be performed for Parkinson's syndrome, Lewy body dementia, and the like.

[Second Embodiment]
FIG. 5 is a diagram illustrating a configuration example of a SPECT apparatus 1A that is an example of a nuclear medicine diagnosis apparatus according to the present embodiment. The SPECT apparatus 1A includes a gantry 11, a top plate 13, a headrest 15, a drive circuit 17, an imaging control circuit 19, gamma cameras 20-1, 20-2, 20-3, a data collection circuit 23, a storage circuit 25A, and a preprocessing circuit. 27, a processing circuit 29A, a display circuit 31, an input interface circuit 33, and a system control circuit 35A.

  The gantry 11, the top plate 13, the headrest 15, the drive circuit 17, the imaging control circuit 19, the gamma cameras 20-1, 20-2 and 20-3, and the data collection circuit 23 are the same as those in the first embodiment. It has a function.

  The storage circuit 25A includes a recording medium readable by a processor, such as a magnetic or optical recording medium or a semiconductor memory. The storage circuit 25A stores a program executed by the circuit of the SPECT apparatus 1 according to the present embodiment. Note that some or all of the programs and data in the storage medium of the storage circuit 25A may be downloaded via an electronic network.

  In addition, the storage circuit 25A stores the projection data generated by the data collection circuit 23. The storage circuit 25A outputs the stored projection data to the preprocessing circuit 27 under the control of the system control circuit 35A.

  The storage circuit 25A stores preprocessing condition information for the preprocessing circuit 27 described later to perform preprocessing. The storage circuit 25A outputs the stored preprocessing condition information to the preprocessing circuit 27 under the control of the system control circuit 35A.

  In addition, the storage circuit 25A stores a database related to the support device and the like. The database related to the support device and the like includes, for example, image data (first X-ray CT image data) acquired by photographing the support device used for the SPECT apparatus 1A and the like using an X-ray CT apparatus, and an image It is a collection of data that handles data incidental information as one logical record.

  The first X-ray CT image data may be either one or a plurality of two-dimensional image data. Further, the first X-ray CT image data may be three-dimensional image data.

  In addition, the database related to the support device or the like is, for example, attenuation map data (hereinafter referred to as “map data”) generated based on image data acquired by photographing the support device or the like used in the SPECT device 1A or the like using an X-ray CT apparatus. , Referred to as first attenuation map data) and incidental information of the attenuation map data as a single logical record.

  In addition, attenuation map data is a method of depicting the distribution of attenuation coefficient in the body from the ratio of X-ray dose transmitted using an X-ray CT apparatus, a method of measuring the attenuation coefficient distribution of gamma rays using an external gamma ray source, and nuclear medicine. Various methods such as a method of obtaining shape information from data such as scattered radiation when acquiring an image and setting an average attenuation coefficient value, or a method of obtaining an organ contour from an MRI image or an X-ray CT image and setting an attenuation coefficient It can be obtained by the method.

  The first attenuation map data may be either one or a plurality of two-dimensional attenuation map data. The first attenuation map data may be three-dimensional attenuation map data.

  Further, the incidental information of the attenuation map data is patient information and examination information. The conditions for identifying the support device, the model number of the apparatus, and a predetermined identification code (for example, such that the SPECT apparatus and the CT apparatus can be distinguished) are included in the conditions therein.

  Further, the storage circuit 25A uses an X-ray CT apparatus to obtain X-ray CT image data (hereinafter referred to as second X-ray) including a support instrument acquired by imaging the subject P while being supported by the support instrument. CT image data) is stored.

  The second X-ray CT image data may be either one or a plurality of two-dimensional image data. Further, the data in the second X-ray CT image may be three-dimensional image data.

  Further, the database may include image data obtained by numerically imaging the shape of the support device used in the SPECT apparatus, the PET apparatus, etc. from the statistical data, and attenuation map data generated based on the image data converted to the numerical image. Good.

  Further, the storage circuit 25A stores first SPECT image data generated by a processing circuit 29A described later.

  The preprocessing circuit 27 has the same configuration and function as those of the first embodiment.

  The display circuit 31 has the same configuration and function as in the first embodiment. The display circuit 31 controls the first X-ray CT image data and the second X-ray CT image data as well as later-described difference image data, difference attenuation map data, composite attenuation map data, first attenuation under the control of the system control circuit 35A. Based on the SPECT image data, the second SPECT image data, and the first attenuation map data, the first X-ray CT image and the second X-ray CT image, and a difference image, a difference attenuation map, a combined attenuation map, which will be described later, A first SPECT image, a second SPECT image, and a first attenuation map are displayed.

  The input interface circuit 33 has the same configuration and function as in the first embodiment.

  The processing circuit 29A generates attenuation map data in consideration of the difference between the support instrument used in the X-ray CT apparatus and the support instrument used in the nuclear medicine diagnosis apparatus, and the nuclear medicine image data to which the created attenuation map data is applied. Is a processor that generates FIG. 5A is a diagram illustrating the contents of first and second X-ray CT image data used in the second embodiment. As shown in FIG. 5A, the first X-ray image data represents a support instrument used in the SPECT apparatus 1A, while the second X-ray CT image data is obtained from the subject P and the X-ray CT apparatus. Represents the support device used. The processing circuit 29A deletes the region representing the support instrument used in the X-ray CT apparatus included in the second X-ray CT image data from the region represented by the second X-ray CT image data. The processing circuit 29 creates attenuation map data from the data representing the deleted region and the first X-ray CT image data, and synthesizes the two attenuation map data thus created, to thereby detect the difference between the support devices. Generate attenuation map data in consideration.

  The processing circuit 29A calls each operation program from the storage circuit 25A and executes the called program, thereby causing the first reconstruction function 291, the image creation function 292A, the attenuation map creation function 293A, and the second reconstruction function 294A. Realize.

  The first reconfiguration function 291 is the same function as in the first embodiment.

  The image creation function 292A is a function for creating a composite image in which a region representing a support instrument used in the X-ray CT apparatus included in the second X-ray CT image data is deleted from the second X-ray CT image data. is there.

  Hereinafter, an example of processing realized by the image creation function 292A is that the support device represented on the first X-ray CT image is only the headrest that does not include the top plate, and is represented on the second X-ray CT image. It is assumed that the supporting device is only a headrest that does not include a top plate.

  First, the processing circuit 29A acquires, for example, the second X-ray CT image data selected by the user from the storage circuit 25A. The processing circuit 29A compares the model number of the SPECT apparatus 1 with the model number included in the incidental information of the plurality of first X-ray CT image data stored in the storage circuit 25A, and corresponds to the record corresponding to the model number. 1 X-ray image data is read from the storage circuit 25A.

  The processing circuit 29A displays a superimposed image obtained by superimposing the first X-ray CT image on the second X-ray CT image on the display circuit 31. The user visually adjusts the position so that the area representing the headrest included in the second X-ray CT image data is included in the area of the headrest represented by the first X-ray CT image data via the input interface circuit 33. The processing circuit 29A performs system control on related information (first related information) indicating to which pixel on the second X-ray CT image each pixel value included in the first X-ray CT image data is assigned. Obtained via circuit 35A.

  For example, the processing circuit 29A has the same pixel size and image matrix size as the second X-ray CT image data, and the first related information is applied to the pixels on the image represented by the image data in which the pixel values of all the pixels are 0. The mask image data to which the pixel value of the first X-ray CT image data is assigned is generated based on

  The processing circuit 29A subtracts the mask image data from the second X-ray CT image data, and deletes the area representing the headrest from the second X-ray CT image. Hereinafter, the image data including the subject P and from which the region representing the headrest used in the subject X-ray CT apparatus is deleted is referred to as difference image data.

  In addition, although the case where difference image data is created using mask image data has been described as an example, the present invention is not limited to this. For example, contour image extraction may be performed to generate difference image data.

  The attenuation map creation function 293A performs attenuation map data (hereinafter referred to as difference attenuation map data) by converting the pixel value of the region representing the subject P included in the difference image data created by the image creation function 292A into a CT value attenuation coefficient value. And the composite attenuation map data is generated by assigning the attenuation coefficient value of the first attenuation map data to the pixels on the difference attenuation map based on the first related information.

  The second reconstruction function 294A applies, for example, the composite attenuation map data created by the attenuation map creation function 293A to the first SPECT image data generated by the first reconstruction function 291 and performs SPECT image data. (Hereinafter, referred to as second SPECT image data).

  For example, by using a registration technique, the processing circuit 29A aligns both images so that a predetermined specific point on the difference image matches a predetermined specific point on the first SPECT image, for example. As a result, the processing circuit 29A multiplies each attenuation coefficient value μ included in the attenuation map data created by the attenuation map creation function 293A to any position in the region represented by the projection data that is the basis of the first SPECT image data. The related information (2nd related information) which shows is acquired.

  The processing circuit 29A performs reconstruction with attenuation correction using the second related information, the projection data and the attenuation map data that are the basis of the first SPECT image data. Accordingly, the processing circuit 29A generates second SPECT image data.

  Next, in the operation of the second embodiment, the support device represented on the first X-ray CT image is only the headrest that does not include the top plate, and the support represented on the second X-ray CT image. A description will be given assuming that the device is only a headrest that does not include a top plate. FIG. 6 is an example of a flowchart of processing performed by various functions of the processing circuit 29A. Hereinafter, the flow of SPECT image reconstruction processing will be described using the example of the flowchart shown in FIG.

  First, the processing circuit 29A displays on the display circuit 31 a superimposed image obtained by superimposing the first X-ray CT image on the second X-ray CT image. The user visually adjusts the position of the headrest region represented by the first X-ray CT image data so as to include the region representing the headrest included in the second X-ray CT image data via the input interface circuit 33. . The processing circuit 29A sends, through the system control circuit 35A, first related information indicating to which pixel on the second X-ray CT image each pixel value included in the first X-ray CT image data is assigned. (Step SB1).

  The processing circuit 29A has the same pixel size and image matrix size as the second X-ray CT image data, and the first related information includes the pixels on the image represented by the image data in which the pixel values of all the pixels are 0. Based on this, mask image data to which the pixel values of the first X-ray CT image data are assigned is generated (step SB2).

  The processing circuit 29A subtracts the pixel value of the mask image data from the pixel value of the second X-ray CT image data. Thereby, the processing circuit 29A deletes the region representing the headrest of the X-ray CT apparatus from the second X-ray CT image (step SB3). Hereinafter, the image data obtained as a result of the deletion is referred to as difference image data as in the first embodiment.

  Next, the processing circuit 29A aligns both images so that a predetermined specific point on the first SPECT image matches a predetermined specific point on the difference image by using, for example, a registration method. . The position of the difference image data is aligned with the first SPECT image data. The processing circuit 29A indicates which position in the region represented by the projection data that is the basis of the first SPECT image data is to be multiplied by the attenuation coefficient value μ included in the attenuation map data generated in step SB6 described later. 2 related information is acquired (step SB4).

  Thereafter, the processing circuit 29A generates the difference attenuation map data by performing the CT value attenuation coefficient value conversion on the pixel value of the area representing the subject P included in the difference image data created in step SB3 (step SB5). ).

  Further, the processing circuit 29A generates composite attenuation map data by assigning the attenuation coefficient value of the first attenuation map data to the pixels on the difference attenuation map based on the first related information (step SB6).

  Finally, the processing circuit 29A uses, for example, the first SPECT image data as the initial image data, and uses the generated composite attenuation map data, the second related information, and the projection data that is the basis of the first SPECT image data. Then, reconstruction is performed by the successive approximation method with attenuation correction. As a result, the processing circuit 29A generates second SPECT image data (step SB7).

  According to the second embodiment, the processing circuit 29A deletes an area representing the support device from the X-ray CT image (second X-ray CT image) of the subject P imaged by the X-ray CT apparatus, and the difference Generate image data. The processing circuit 29A generates difference attenuation map data based on the difference image data. The processing circuit 29A adds an attenuation map (first attenuation map) representing the support device used in the SPECT apparatus 1 to a region where the region representing the support device is deleted from the generated difference attenuation map. Generate synthetic attenuation map data. The processing circuit 29A uses the generated composite attenuation map data, the second related information, and the projection data that is the basis of the first SPECT image data to perform reconstruction with attenuation correction, thereby performing the second SPECT. Generate image data. Accordingly, even if the support instrument used in the SPECT apparatus for imaging the subject P and the support instrument used in the X-ray CT apparatus are different in shape and material, the difference between the support instruments can be reduced. It is possible to correct the first SPECT image data using the attenuation map data considered.

  Therefore, according to the SPECT apparatus 1A according to the present embodiment, it is possible to improve the accuracy of correction using the attenuation map.

  Similarly to the first embodiment, by improving the accuracy of correction using the attenuation map, a semi-quantitative value such as SUV (Standardized Uptake value) of the PET image can be obtained for the corrected SPECT image. Be expected. If a quantitative value is obtained, accurate image diagnosis can be performed for Parkinson's syndrome, Lewy body dementia, and the like.

[Third Embodiment]
In 1st and 2nd embodiment, the case where the attenuation | damping map data was produced | generated based on the X-ray CT image data in which the pixel value showing a support instrument is contained in image data was demonstrated. This embodiment demonstrates the case where attenuation map data are produced | generated based on MRI image data in which the pixel value showing a support instrument is not contained in image data.

  FIG. 7 is a diagram illustrating a configuration example of a SPECT apparatus 1B that is an example of the nuclear medicine diagnosis apparatus according to the present embodiment. The SPECT apparatus 1B includes a gantry 11, a top plate 13, a headrest 15, a drive circuit 17, an imaging control circuit 19, gamma cameras 20-1, 20-2, and 20-3, a data collection circuit 23, a storage circuit 25B, and a preprocessing circuit. 27, a processing circuit 29B, a display circuit 31, an input interface circuit 33, and a system control circuit 35B.

  The gantry 11, the top plate 13, the headrest 15, the drive circuit 17, the imaging control circuit 19, the gamma cameras 20-1, 20-2, 20-3, and the data collection circuit 23 are the same as those in the first and second embodiments. It has the structure and function.

  The storage circuit 25B includes a recording medium readable by a processor, such as a magnetic or optical recording medium or a semiconductor memory. The storage circuit 25B stores a program executed by the circuit of the SPECT apparatus 1B according to the present embodiment. Note that some or all of the programs and data in the storage medium of the storage circuit 25B may be downloaded via an electronic network.

  The storage circuit 25B stores the projection data generated by the data collection circuit 23. The storage circuit 25B outputs the stored projection data to the preprocessing circuit 27 under the control of the system control circuit 35B.

  The storage circuit 25B stores preprocessing condition information for the preprocessing circuit 27 described later to perform preprocessing. The storage circuit 25B outputs the stored preprocessing condition information to the preprocessing circuit 27 under the control of the system control circuit 35B.

  In addition, the storage circuit 25B stores a database related to the support device and the like. The database related to the support device and the like includes, for example, image data (first X-ray CT image data) acquired by imaging the support device used in the SPECT apparatus 1B and the like with the X-ray CT apparatus, and additional information of the image data Is a collection of data that treats and as one logical record.

  The first X-ray CT image data is a set of CT values assigned to each pixel in a region representing a support instrument used in the SPECT apparatus. The first X-ray CT image data may be either one or a plurality of two-dimensional image data. Further, the first X-ray CT image data may be three-dimensional image data.

  In addition, the database related to the support device or the like is, for example, attenuation map data (hereinafter referred to as “attenuation map data”) generated based on image data acquired by photographing the support device used in the SPECT device 1B or the like using an X-ray CT apparatus. , Referred to as first attenuation map data) and incidental information of the attenuation map data as a single logical record.

  The first attenuation map data is composed of a set of attenuation coefficient values obtained by converting the CT value (HU value) for each pixel in the region representing the support device used in the SPECT apparatus 1A into the attenuation coefficient μ, for example. The first attenuation map data may be either one or a plurality of two-dimensional attenuation map data. The first attenuation map data may be three-dimensional attenuation map data.

  Further, the incidental information of the attenuation map data is patient information and examination information. The conditions for identifying the support device, the model number of the apparatus, and a predetermined identification code (for example, such that the SPECT apparatus and the CT apparatus can be distinguished) are included in the conditions therein.

  Further, the database may include image data obtained by numerically imaging the shape of the support device used in the SPECT apparatus, the PET apparatus, etc. from the statistical data, and attenuation map data generated based on the image data converted to the numerical image. Good.

  Further, the storage circuit 25B stores attenuation map data (hereinafter referred to as second attenuation map data) generated based on MRI image data acquired by imaging the subject P using the MRI apparatus.

MRI is an imaging method based on a magnetic resonance phenomenon, in which an atomic nucleus (such as ¹ H) spin of a subject placed in a space where a static magnetic field is formed is magnetized by an RF (Radio Frequency) signal having a Larmor frequency. This is an imaging method in which an image is reconstructed from MR (Magnetic Resonance) signals generated in response to excitation. Therefore, in the MRI image data obtained as a result of imaging by the MRI apparatus, only the tissue containing hydrogen appears as the pixel value of the image data. For example, the bone made of calcium made of a substance not containing hydrogen and the support used in the MRI apparatus, etc. An appliance or the like does not appear as a pixel value of image data.

  The MRI image data may be either one or a plurality of two-dimensional image data. Further, the MRI image data may be three-dimensional image data.

  The MRI image data is a set of values obtained by performing an inverse Fourier transform on MR signals assigned to each pixel representing the subject P. The second attenuation map data is composed of a set of attenuation coefficient values obtained by converting each pixel value of the MRI image data into an attenuation coefficient μ.

  Note that the storage circuit 25B uses image data and a numerical image obtained by converting a statistical image into a numerical image of the shape of the subject P or a specific portion of the subject P that does not include a support instrument used in the X-ray CT apparatus or the MRI apparatus. The attenuation map data generated based on the converted image data may be stored as the second attenuation map data.

  Further, the storage circuit 25B stores first SPECT image data generated by a processing circuit 29B described later.

  The preprocessing circuit 27 has the same configuration and function as those of the first and second embodiments.

  The display circuit 31 has the same configuration and function as those in the first and second embodiments. The display circuit 31 controls the first X-ray CT image data, the second X-ray CT image data, the synthetic attenuation map data, the first SPECT image data, and the second SPECT image, which will be described later, under the control of the system control circuit 35B. Based on the data, the first attenuation map data and the second attenuation map data, the first X-ray CT image and the first attenuation map, a second attenuation map combined attenuation map, which will be described later, a first SPECT image, Each second SPECT image is displayed.

  The input interface circuit 33 has the same configuration and function as those in the first and second embodiments.

  The processing circuit 29B generates composite attenuation map data obtained by adding the first attenuation map data to the attenuation map data (second attenuation map data) generated based on the MRI image data, and generates the generated synthetic attenuation map data. A processor for generating applied nuclear medicine image data. FIG. 7A is a diagram for explaining the contents of the first and second attenuation map data used in the third embodiment. As shown in FIG. 7A, the first attenuation map data represents the support device used in the SPECT apparatus 1B, while the second attenuation map data represents only the subject P. The processing circuit 29 adds the first attenuation map data to the second attenuation map data, and generates the synthetic attenuation map data considering that the second attenuation map data does not include the support device used in the SPECT device 1B. Generate.

  The processing circuit 29B calls each operation program from the storage circuit 25B and executes the called program, thereby realizing the first reconstruction function 291, the smoothing function 295, the attenuation map creation function 293B, and the second reconstruction function 294B. To do.

  The first reconfiguration function 291 is the same function as in the first and second embodiments.

  The smoothing function 295 is a function that removes high-frequency noise components from the first attenuation map data using a low-pass filter or the like. The smoothing function 295 may remove high frequency noise components from the first X-ray CT image data using a low-pass filter or the like.

  The attenuation map creation function 293B is a composite attenuation map data obtained by adding the attenuation coefficient value of the first attenuation map data from which the high frequency noise component has been removed by the smoothing function 295 to the second attenuation map data stored in the storage circuit 25B. It is a function to generate.

  Hereinafter, an example of processing realized by the attenuation map creation function 293B will be described on the assumption that the support device represented on the second X-ray CT image is only a headrest that does not include a top plate.

  First, the processing circuit 29B acquires, for example, the second attenuation map data selected by the user from the storage circuit 25B. Further, the processing circuit 29B compares the model number of the SPECT device 1B with the model number included in the incidental information of the plurality of first attenuation map data stored in the storage circuit 25B, and the first corresponding to the record with the matching model number The attenuation map data is read from the storage circuit 25B.

  The processing circuit 29B displays on the display circuit 31 a superimposition map obtained by superimposing the first attenuation map on the second attenuation map. The user visually adjusts the position through the input interface circuit 33 so that the predetermined area included in the second attenuation map data includes the headrest area represented by the first attenuation map data. As a result, the processing circuit 29B uses the related information indicating which position on the second attenuation map the attenuation coefficient value included in the first attenuation map data is assigned as the third related information. Obtained via 35B.

  The predetermined area is centered on a position that is a predetermined distance away from the anatomical reference position of the subject P stored in the storage circuit 25, for example, and has the same shape and area as the first attenuation map. It is an area.

  The processing circuit 29B generates composite attenuation map data by assigning the attenuation coefficient value of the first attenuation map data to the pixels on the second attenuation map based on the third related information.

  For example, the second reconstruction function 294B applies the composite attenuation map data created by the attenuation map creation function 293B to the first SPECT image data generated by the first reconstruction function 291 and has attenuation correction. This is a function for generating SPECT reconstructed image data (hereinafter referred to as second SPECT image data).

  In the second reconstruction function 294B, the processing circuit 29B generates first SPECT image data based on the projection data preprocessed by the preprocessing circuit 27, for example.

  The processing circuit 29B uses, for example, a registration method such as rigid body transformation or affine transformation, so that both predetermined specific points on the first SPECT image are matched with predetermined specific points on the first SPECT image, for example. Align the image. The processing circuit 29B uses, as related information of the fourth related information, related information indicating which position in the region represented by the first SPECT image data is multiplied by each attenuation coefficient value μ included in the combined attenuation map data. Obtained via the system control circuit 35B. The predetermined specific point is a point determined by, for example, converting the first SPECT image or the composite attenuation map into a binary image and obtaining the center of gravity.

  The processing circuit 29B performs reconstruction with attenuation correction using the fourth related information, the projection data that is the basis of the first SPECT image data, and the synthetic attenuation map data, and generates second SPECT image data. .

  Next, the operation of the third embodiment will be described on the assumption that the support device represented on the second X-ray CT image is only a headrest that does not include a top plate. FIG. 8 is an example of a flowchart of processing performed by various functions of the processing circuit 29B. Hereinafter, the flow of the SPECT image reconstruction process will be described using the example of the flowchart shown in FIG.

  First, the processing circuit 29B displays on the display circuit 31 a superimposition map obtained by superimposing the first attenuation map on the second attenuation map. The user visually adjusts the position through the input interface circuit 33 so that the predetermined area included in the second attenuation map data includes the headrest area represented by the first attenuation map data. The processing circuit 29B acquires, via the system control circuit 35B, third related information indicating to which pixel on the second attenuation map the attenuation coefficient value included in the first attenuation map data is assigned ( Step SC1).

  The processing circuit 29A removes the high frequency noise component from the first attenuation map data using a low pass filter or the like (step SC2).

  The processing circuit 29B uses, for example, a registration method to position both images so that the predetermined specific point on the second attenuation map matches the predetermined specific point on the first SPECT image. Match. The processing circuit 29B has associated information (fourth information) indicating which position in the region represented by the projection data that is the basis of the first SPECT image data is multiplied by each attenuation coefficient value μ included in the second attenuation map data. Related information) is acquired (step SC3).

  The processing circuit 29B assigns the attenuation coefficient value of the first attenuation map data from which the high-frequency noise component has been removed in step SC2 to the pixels on the second attenuation map based on the third related information, thereby combining the attenuation map data. Is generated (step SC4).

  Finally, the processing circuit 29B uses, for example, the first SPECT image data as the initial image data, and uses the generated composite attenuation map data, the fourth related information, and the projection data that is the basis of the first SPECT image data. Then, reconstruction is performed by the successive approximation method with attenuation correction. Accordingly, the processing circuit 29B generates second SPECT image data (step SC5).

  According to the third embodiment, the processing circuit 29B attenuates the first attenuation map data in which the high frequency noise component is removed in step SC2 to the pixels on the second attenuation map based on the third related information. Synthetic attenuation map data is generated by assigning numerical values. The processing circuit 29B uses the generated composite attenuation map data, the fourth related information, and the projection data that is the basis of the first SPECT image data to perform reconstruction by the successive approximation method with attenuation correction. Thereby, even if the MRI image data in which the pixel value of the region representing the support instrument used in the SPECT apparatus 1B for imaging the subject P is not included in the image data, the SPECT apparatus 1B that actually images the subject P is used. It becomes possible to correct | amend 1st SPECT image data using the attenuation map data in consideration of the support instrument used.

  Therefore, according to the SPECT apparatus 1B according to the present embodiment, the accuracy of correction using the attenuation map can be improved.

  Further, as in the first and second embodiments, by improving the accuracy of correction using the attenuation map, a semi-quantitative value such as SUV (Standardized Uptake value) of the PET image is obtained for the corrected SPECT image. It is expected to be found. If a quantitative value is obtained, accurate image diagnosis can be performed for Parkinson's syndrome, Lewy body dementia, and the like.

[Other Embodiments]
The present invention is not limited to the above embodiment. For example, in the first, second, and third embodiments, regarding a support instrument used in a SPECT apparatus that images a subject, when a deflection or the like is generated due to the weight of the subject at the time of imaging, the positional deviation is detected. You may make it correct. Hereinafter, a method of adjusting the positional deviation such as deflection will be described based on the first embodiment with reference to FIGS. At this time, it is assumed that the first SPECT image and the first X-ray CT image are three-dimensional images.

  FIG. 11 is a diagram illustrating a functional configuration of the reconfiguration circuit C in which the position adjustment function 296 is added to the processing circuit 29 in the first embodiment.

  The processing circuit 29C calls up each operation program from the storage circuit 25, and implements the position adjustment function 296 by executing the called program.

  The position adjustment function 296 is a function that adjusts the position of the corresponding cross section of the first X-ray CT image that is a three-dimensional image on the sagittal image that represents the sagittal cross section of the first SPECT image that is a three-dimensional image. is there.

  In the position adjustment function 296, the processing circuit 29C causes the system control circuit 35 to display a sagittal image representing a sagittal section of the first SPECT image that is a three-dimensional image. For example, as shown in FIG. 9, the user determines the position of the first X-ray CT image with respect to the first SPECT image via the input interface circuit 33 while confirming the sagittal image displayed on the display circuit 31. Specify any reference line. The reference line may be specified by connecting a plurality of lines or by a curve.

  For example, the processing circuit 29C aligns the first SPECT image so that the region represented by the first X-ray CT image data is along the designated reference line. The processing circuit 29C determines which pixel value in the region represented by the first SPECT image data is to be multiplied by each attenuation coefficient value μ included in the attenuation map data generated based on the first X-ray CT image. Is obtained via the system control circuit 35 as fifth related information.

  The processing circuit 29C superimposes the first X-ray CT image on the first SPECT image, which is a three-dimensional image, based on the fifth related information, for example, via the system control circuit 35, and the three-dimensional superimposed image data. Is generated. As illustrated in FIG. 10, the processing circuit 29 </ b> C displays a transverse image representing a transverse section of the three-dimensional superimposed image represented by the generated three-dimensional superimposed image data on the display circuit 31 via the system control circuit 35. . Note that the transverse cross section of the first X-ray CT image is one of a plurality of transverse images obtained by imaging a supporting instrument used in the SPECT apparatus 1 in advance using the X-ray CT apparatus under predetermined imaging conditions. But you can.

  The processing circuit 29 generates a plurality of transverse images at regular intervals based on, for example, a three-dimensional superimposed image, and displays it on the display circuit 31 for each cross section. The user visually observes the transverse image displayed on the display circuit 31 and adjusts the position of the first X-ray CT image with respect to the first SPECT image via the input interface circuit 33.

  As a result, it is possible to correct the misalignment of the support device used in the SPECT apparatus for imaging the subject even when the deflection is caused by the weight of the subject during imaging.

  In the position adjustment function, the processing circuit 29 aligns the second X-ray CT image with the first SPECT image based on position information indicating the height of the bed stored in advance in the storage circuit 25, for example. You may make it perform automatically.

  The term “processor” used in the above description is, for example, a central processing unit (CPU), a graphics processing unit (GPU), or an application specific integrated circuit (ASIC)), a programmable logic device (for example, It means a circuit such as a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA). The processor implements a function by reading and executing a program stored in the storage circuit. Instead of storing the program in the storage circuit, the program may be directly incorporated in the processor circuit. In this case, the processor realizes the function by reading and executing the program incorporated in the circuit. Note that each processor of the present embodiment is not limited to being configured as a single circuit for each processor, but may be configured as a single processor by combining a plurality of independent circuits to realize the function. Good. Further, a plurality of components shown in FIGS. 1, 5 and 7 may be integrated into one processor to realize the function.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1, 1A, 1B ... SPECT apparatus, 11 ... Gantry, 12 ... Rotating frame, 13 ... Top plate, 15 ... Headrest, 17 ... Drive circuit, 19 ... Imaging control circuit, 21-1, 21-2, 21-3 ... Gamma ray detector, 23 ... Data acquisition circuit, 25, 25A, 25B ... Memory circuit, 27 ... Pre-processing circuit, 29, 29A, 29B, 29C ... Processing circuit, 31 ... Display circuit, 33 ... Input interface circuit, 35, 35A 35B System control circuit.

Claims (13)

A storage unit for storing first morphological image data representing a region of the first support instrument used in the nuclear medicine diagnostic apparatus;
The image represented by the first morphological image data is aligned with the image represented by the second morphological image data representing the region on which the subject is projected and the region of the second support instrument used in the X-ray CT apparatus. An alignment unit to be
A deletion unit that deletes a region representing the second support device from the image represented by the second morphological image data;
An image data generation unit that assigns a pixel value of the first morphological image data after the alignment to pixels of an image represented by the second morphological image data after the deletion, and generates composite image data;
An attenuation map data generation unit that generates attenuation map data from the composite image data generated by the image data generation unit;
A nuclear medicine diagnostic apparatus comprising: a reconstruction unit that reconstructs nuclear medicine projection data related to the subject based on the generated attenuation map data.   2. The nuclear medicine diagnosis apparatus according to claim 1, wherein the first support device is at least one of a top plate and a headrest, and the second support device is at least one of a top plate and a headrest. .   The first medical image data and the first medical image data generated from the nuclear medicine projection data are superimposed, and based on the degree of distortion caused by the weight of the subject with respect to the first support device, the first The nuclear medicine diagnosis apparatus according to claim 1, further comprising a position adjustment unit that adjusts a position of the morphological image data. A display unit;
A control unit that causes the display unit to display a superimposed image in which a cross-sectional image based on nuclear medicine image data generated from the nuclear medicine projection data and a cross-sectional image based on the first morphological image data are superimposed;
Any one of Claims 1 thru | or 3 which further has an input reception part for changing at least any one among the position and shape of a said 1st form image data on the said superimposition image displayed by the said display part. The nuclear medicine diagnostic apparatus according to any one of the above. A storage unit for storing first morphological image data representing a region of the first support instrument used in the nuclear medicine diagnostic apparatus;
The image represented by the first morphological image data is aligned with the image represented by the second morphological image data representing the region on which the subject is projected and the region of the second support instrument used in the X-ray CT apparatus. An alignment unit to be
A deletion unit that deletes an area for the second support device from the image represented by the second morphological image data;
An attenuation map data generation unit for generating attenuation map data from the second form image data from which the region has been deleted;
An assigning unit that assigns an attenuation coefficient value generated from the first morphological image data after the alignment to the attenuation map data;
A nuclear medicine diagnostic apparatus comprising: a reconstruction unit that reconstructs nuclear medicine projection data related to the subject based on attenuation map data to which the attenuation coefficient value is assigned.   The nuclear medicine diagnostic apparatus according to claim 5, wherein the first support device is at least one of a top plate and a headrest, and the second support device is at least one of the top plate and a headrest. .   The first medical image data and the first medical image data generated from the nuclear medicine projection data are superimposed, and based on the degree of distortion caused by the weight of the subject with respect to the first support device, the first The nuclear medicine diagnosis apparatus according to claim 5, further comprising a position adjustment unit that adjusts the position of the morphological image data. A display unit;
A control unit that causes the display unit to display a superimposed image in which a cross-sectional image based on nuclear medicine image data generated from the nuclear medicine projection data and a cross-sectional image based on the first morphological image data are superimposed;
The input receiving unit for further changing at least one of the position and shape of the first form image data on the superimposed image displayed by the display unit. The nuclear medicine diagnostic apparatus according to any one of the above. A storage unit for storing first morphological image data representing a region of the first support instrument used in the nuclear medicine diagnostic apparatus;
Generated from the first morphological image data with respect to attenuation map data generated from the second morphological image data that represents the region onto which the subject is projected and does not have the region that represents the first support device. An assigning unit for assigning attenuation coefficient values to be
A nuclear medicine diagnosis apparatus comprising: a reconstruction unit that reconstructs nuclear medicine projection data related to the subject based on attenuation map data to which the attenuation coefficient value is assigned.   The nuclear medicine diagnosis according to claim 9, wherein the second morphological image data is any of image data obtained by numerically imaging the shape of the subject or a specific portion of the subject from MRI image data and statistical data. apparatus.   The nuclear medicine diagnosis apparatus according to claim 9 or 10, wherein the first support device is at least one of a top plate and a headrest.   The first medical image data and the first medical image data generated from the nuclear medicine projection data are superimposed, and based on the degree of distortion caused by the weight of the subject with respect to the first support device, the first The nuclear medicine diagnosis apparatus according to claim 9, further comprising a position adjustment unit that adjusts a position of the morphological image data. A display unit;
A control unit that causes the display unit to display a superimposed image in which a cross-sectional image based on nuclear medicine image data generated from the nuclear medicine projection data and a cross-sectional image based on the first morphological image data are superimposed;
The input receiving unit for changing at least one of the position and shape of the first morphological image data on the superimposed image displayed by the display unit. The nuclear medicine diagnostic apparatus according to any one of the above.