JP7209496B2 - nuclear medicine diagnostic equipment - Google Patents

Description

Embodiments of the present invention relate to a nuclear medicine diagnostic apparatus.

Nuclear medicine diagnostic equipment such as SPECT (Single Photon Emission computed tomography) equipment selectively directs chemicals (blood flow markers, tracers) containing radioisotopes (hereinafter referred to as RI) to specific tissues and organs in the body. Gamma rays emitted from RI distributed in vivo are detected by a gamma camera having a gamma ray detector arranged outside the living body, using the property of being taken in. A nuclear medicine diagnostic apparatus can provide a functional image of internal organs by generating a nuclear medicine image in which the dose distribution of gamma rays detected by a gamma ray detector is imaged.

One of the features of nuclear medicine examination is that the amount of administered RI accumulated in the subject can be quantitatively determined. For example, when performing a diagnosis using quantitative values in a SPECT examination, it is possible to perform a diagnosis using quantitative values with high accuracy by accurately correcting the effects of attenuation, scattered radiation, and positional resolution (partial volume effect).

Attenuation refers to the attenuation of gamma rays emitted from the RI due to internal tissues and the like. In order to consider this attenuation, a nuclear medicine diagnostic apparatus generally performs correction (attenuation correction) based on an attenuation correction coefficient image generated from an attenuation coefficient image when generating a nuclear medicine image. Accurate attenuation correction can improve the accuracy of quantitative values obtained from reconstructed nuclear medicine images.

However, when an absorber (hereinafter referred to as a non-subject member) exists outside the effective field of view of the attenuation coefficient image, it is difficult to perform attenuation correction considering the attenuation effect of this non-subject member, and the accuracy of attenuation correction is will drop significantly.

Japanese Patent Application Publication No. 2011-521224

A problem to be solved by the present invention is to generate a nuclear medicine image in which the influence of attenuation due to non-subject members outside the effective field of the attenuation coefficient image is corrected.

A nuclear medicine diagnosis apparatus according to an embodiment includes an acquisition unit, a generation unit, a reception unit, an extraction unit, and an interpolation enlargement unit. The acquisition unit acquires an attenuation coefficient image consisting of a reconstruction region of an effective field of view (referred to as a first size) of a non-subject member for SPECT without truncation, which is imaged by an X-ray CT apparatus. The generator generates an attenuation correction coefficient image made up of a reconstruction area of a first size based on the attenuation coefficient image. The reception unit receives information regarding the acquisition of a nuclear medicine image of a reconstruction region with an effective field of view (referred to as a second size) of SPECT acquisition data that is smaller than the reconstruction region of the first size. The extraction unit extracts a range corresponding to the reconstruction area of the second size from the attenuation correction coefficient image. The interpolation enlarging unit interpolates and enlarges the attenuation correction coefficient image of the extracted range based on the reconstruction area of the first size and the reconstruction area of the second size.

1(a) is a block diagram showing an example of a nuclear medicine diagnostic apparatus according to a first embodiment, and FIG. 1(b) is a cross-sectional view taken along line X-X' of FIG. 1(a); FIG. 2 is a block diagram schematically showing an internal configuration example of a nuclear medicine diagnostic apparatus; FIG. 2 is a schematic block diagram showing an example of functions realized by a processor of the processing circuit according to the first embodiment; FIG. 10 is a diagram for explaining a case where a non-subject member exists outside the effective field of view of the attenuation map; The processor of the processing circuit shown in FIG. 1 performs preprocessing to generate a preprocess reconstructed SPECT image (a SPECT image in which only the attenuation correction of the non-subject member is not performed) using the attenuation map that does not include the non-subject member. 4 is a flowchart showing an example of a procedure for execution; 4 is a flow chart showing an example of a procedure when the processor of the processing circuit shown in FIG. 1 executes post-processing for performing only attenuation correction of a non-subject member on a pre-process reconstructed SPECT image. FIG. 4 is an explanatory diagram showing an example of the relationship between the effective field of view of an X-ray CT image (effective field of view of an attenuation map) and the effective field of view of an attenuation correction coefficient image in post-processing according to the first embodiment; FIG. 10 is a schematic block diagram showing an example of functions realized by a processor of a processing circuit of a nuclear medicine imaging apparatus according to the second embodiment; FIG. 11 is a flowchart showing an example of a procedure for performing post-processing for performing attenuation correction on a non-subject member using a 3D attenuation correction map for preprocessing reconstructed SPECT images by the processor of the processing circuit according to the second embodiment; FIG. .

Hereinafter, embodiments of a nuclear medicine diagnostic apparatus will be described in detail with reference to the drawings.

The nuclear medicine diagnostic apparatus according to this embodiment can be applied to a single apparatus having a gamma ray detector such as SPECT or PET (Positron Emission Tomography). Further, the nuclear medicine diagnostic apparatus according to the present embodiment is a SPECT-CT apparatus or PET-CT apparatus that is combined with an apparatus such as an X-ray CT (Computed Tomography) apparatus in which a device equipped with a gamma ray detector generates a morphological image. It is also possible to apply to a composite device such as. An example of the case of using a three-detector type gamma ray detector rotation type SPECT apparatus as a nuclear medicine diagnostic apparatus according to the present invention will be described below. The gamma ray detector rotation type SPECT apparatus may have one, two, or four or more gamma ray detectors.

(First embodiment)
FIG. 1(a) is a block diagram showing an example of a nuclear medicine diagnostic apparatus 1 according to the first embodiment, and (b) is a cross-sectional view taken along line XX' of (a). FIG. 2 is a block diagram schematically showing an internal configuration example of the nuclear medicine diagnostic apparatus 1. As shown in FIG.
The nuclear medicine diagnostic apparatus 1 has a gantry device 10, a bed device 20, and a console 30, as shown in FIG. 1(a).

The gantry device 10 has a gantry body 11 forming a cylindrical imaging space therein, and three gamma ray detectors 12a, 12b and 12c. The gantry 10 further includes three collimators 13a, 13b and 13c detachably attached to the three gamma ray detectors 12a, 12b and 12c, respectively, and a rotation drive device 14.

The gantry main body 11 includes a base, a fixed pedestal composed of a housing fixed to the base, and a rotary pedestal including a rotating plate rotatably supported with respect to the fixed pedestal. The fixed pedestal and the rotating pedestal are covered, for example, by a pedestal cover. The central portion of the fixed pedestal, the rotatable pedestal, and the pedestal cover that covers them is provided with an opening that encloses the imaging region.

As shown in FIG. 1(b), the nuclear medicine diagnostic apparatus 1 according to the present embodiment is a three-detector rotating gamma-ray detector having three gamma-ray detectors 12a, 12b and 12c arranged in a triangular shape. type SPECT device.

Three gamma ray detectors 12a, 12b and 12c are held on a rotating cradle. By rotating the rotating gantry about the rotation axis (about the z-axis) via the rotation drive device 14, the three gamma ray detectors 12a, 12b and 12c are rotated as one about the rotation axis.

The gamma ray detector 12a detects gamma rays emitted from RI (radioisotopes) such as technetium administered to a subject (for example, a patient). Note that the gamma ray detectors 12b and 12c have the same configuration and action as the gamma ray detector 12a, so description thereof will be omitted.

The gamma ray detector 12a detects gamma rays emitted from RIs (radioisotopes) such as Tl-201 and Tc-99m administered to a subject (for example, a patient) P. Note that the gamma ray detectors 12b and 12c have the same configuration and action as the gamma ray detector 12a, so description thereof will be omitted. The gamma ray detector 12a may be a scintillator type detector or a semiconductor type detector.

When the gamma ray detector 12a is a scintillator type detector, the gamma ray detector 12a includes a collimator 13a for regulating the incident angle of gamma rays, and a scintillator that emits an instantaneous flash when the gamma rays collimated by the collimator 13a are incident. , a light guide, a plurality of photomultiplier tubes arranged two-dimensionally for detecting light emitted from the scintillator, an electronic circuit for the scintillator, and the like. The scintillator is composed of, for example, thallium-activated sodium iodide NaI (Tl).

The electronic circuit for the scintillator acquires incident position information of the gamma rays within the detection plane composed of the multiple photomultiplier tubes based on the outputs of the multiple photomultiplier tubes each time an event of incident gamma rays occurs. (Position information), incident intensity information and incident time information are generated and output to the processing circuit 35 of the console 30 . This position information may be two-dimensional coordinate information within the detection plane, or the detection plane may be virtually divided in advance into a plurality of divided regions (primary cells) (for example, divided into 128×128 cells). ), and information indicating to which primary cell the incident occurred.

On the other hand, when the gamma ray detector 12a is a semiconductor type detector, the gamma ray detector 12a includes a collimator 13a and a plurality of two-dimensionally arranged semiconductor devices for detecting gamma rays for detecting the gamma rays collimated by the collimator 13a. It has an element (hereinafter referred to as a semiconductor element), an electronic circuit for a semiconductor, and the like. The semiconductor element is made of CdTe or CdZnTe (CZT), for example.

The semiconductor electronic circuit generates incident position information, incident intensity information, and incident time information based on the output of the semiconductor element each time a gamma ray incident event occurs, and outputs the information to the processing circuit 35 . This positional information is information indicating which semiconductor element among a plurality of semiconductor elements (eg, 128×128 pieces) the light is incident on.

That is, the gamma ray detector 12a outputs incident position information, incident intensity information, and incident time information for each event. The positional information is at least one of information indicating which position of the primary cell the gamma ray is incident on and information on two-dimensional coordinates within the detection plane.

The gamma ray detectors 12 a , 12 b and 12 c are controlled by the processing circuit 35 in imaging timing.

Each of the collimators 13a, 13b and 13c is made of a material such as lead or tungsten that does not easily transmit radiation, and is provided with a plurality of holes for regulating the direction of incoming photons. This hole has a polygonal shape, for example a hexagon.

The rotation drive device 14 includes rotating means such as a motor for rotating the rotating base at high speed around a predetermined rotation axis r, electronic components for controlling the rotation of the rotating means, and transmission of the rotation of the rotating means to the rotating base. It has a transmission means such as a roller for The rotary drive device 14 is controlled by the processing circuit 35 via the data acquisition circuit 15 to rotate the rotary gantry around a predetermined rotation axis r. For example, the processing circuitry 35 rotates the gamma ray detectors 12a, 12b, and 12c around the subject P continuously or stepwise via the rotating gantry to obtain SPECT projection data of the subject from a plurality of directions. , called projection data) can be collected.

The data acquisition circuit 15 is composed of, for example, a printed circuit board, and is controlled by a processing circuit 35 to control the gamma ray detectors 12a, 12b and 12c, the rotation drive device 14 and the table drive device 23, so that the subject P imaging.

Data acquisition circuit 15 acquires the outputs of gamma ray detectors 12 a , 12 b and 12 c in list mode, for example, and outputs the acquired projection data to console 30 . In the list mode, gamma ray detection position information, intensity information, information indicating the relative positions of the gamma ray detectors 12a, 12b and 12c and the subject P (positions and angles of the gamma ray detectors 12a, 12b and 12c, etc.), and gamma ray is collected for each gamma-ray incident event.

The bed device 20 has a top plate 21 , a bed main body 22 for moving the top plate 21 vertically and horizontally, and a top plate driving device 23 for moving the top plate 21 .

The top plate 21 is configured by a plate-like member having a longitudinal direction in the z-axis direction and a lateral direction in the x-axis direction. A subject is placed on the top plate 21 . A subject P is placed on the top plate 21 .

The bed main body 22 is installed on the floor and supports the top board 21 so that it can be raised and lowered. For example, the bed main body 22 has two elongated support members arranged in an X shape, and a connecting pin that pivotally supports the central portions of the two support members. The top plate 21 is supported by . In this case, for example, the top plate 21 is raised by narrowing the space between the lower ends of the two support members, and lowered by widening the space between the bottom ends.

The table driving device 23 is controlled by the processing circuit 35 via the data collection circuit 15 to move the table 21 . Specifically, the tabletop driving device 23 has a motor as a drive source for moving the tabletop 21 along the z-axis direction and the x-axis direction, electronic components for controlling the motor, and the like. In addition, the table top driving device 23 has a motor as a driving source for moving the table 21 up and down, electronic components for controlling the motor, and the like.

On the other hand, the console 30 of the nuclear medicine diagnostic apparatus 1 is composed of, for example, a general personal computer or workstation, and has an input circuit 31, a display 32, a memory circuit 33, a network connection circuit 34 and a processing circuit 35. Note that the console 30 may not be provided independently, and for example, a part of the components 31 to 35 of the console 30 may be provided dispersedly on the fixed pedestal 16 .

The input circuit 31 is composed of general input devices such as a trackball, switch button, mouse, keyboard, numeric keypad, etc., and outputs an operation input signal corresponding to a user's operation to the processing circuit 35 . For example, the user can specify the region to be imaged and the RI used in the examination via the input circuit 31 .

The display 32 is composed of a general display output device such as a liquid crystal display or an OLED (Organic Light Emitting Diode) display.

The storage circuit 33 has a configuration including a processor-readable recording medium such as a magnetic or optical recording medium or a semiconductor memory. The storage circuit 33 is controlled by the processing circuit 35 to store the count value (input count number) for each display pixel and the nuclear medicine image. A part or all of the programs and data in these recording media may be configured to be downloaded by communication via an electronic network.

The network connection circuit 34 is composed of, for example, a network card having a predetermined printed circuit board, and implements various information communication protocols according to the form of the network. The network connection circuit 34 connects the nuclear medicine diagnostic apparatus 1 and other devices according to these various protocols. An electrical connection via an electronic network or the like can be applied to this connection. The term “electronic network” as used herein refers to all information communication networks using telecommunication technology, including wireless/wired hospital LANs (Local Area Networks), Internet networks, telephone communication networks, optical fiber communication networks, cable networks, etc. Including communication networks and satellite communication networks.

The processing circuit 35 reads out and executes a program stored in the storage circuit 33 to correct the influence of attenuation by the non-subject member 52 outside the effective field of the attenuation coefficient image (attenuation coefficient map, hereinafter referred to as attenuation map). It is a processor that executes processing for generating a nuclear medicine image.

FIG. 3 is a schematic block diagram showing an example of functions realized by the processor of the processing circuit 35 according to the first embodiment. FIG. 4 is a diagram for explaining a case where a non-subject member exists outside the effective field of view of the attenuation map.

By the way, the effective field of view of the SPECT image 60 (reconstruction area of the second size, eg 210 mm×210 mm) is larger than the effective field of view of the X-ray CT image 51 (reconstruction area of the first size, eg 256 mm×256 mm). There are small things. In this case, it is necessary to align the X-ray CT image 51 with the SPECT image (see the right side of FIG. 4).

However, when the effective visual field of the SPECT image 60 is smaller than the effective visual field of the X-ray CT image 51, part of the non-subject member 52 such as the headrest and the tabletop 21 included in the X-ray CT image 51 is missing ( truncation) may occur. In this case, an attenuation map is generated based on the X-ray CT image 51 in which the non-subject member 52 is partially cut off. In this case, since the attenuation correction map is generated based on this attenuation map, it becomes difficult to correct the influence of the attenuation by the non-subject member 52 outside the effective field of the attenuation map. .

Therefore, the processing circuit 35 according to the present embodiment uses an attenuation map that does not include the non-subject member 52 as preprocessing to perform a preprocessing reconstructed SPECT image having a second size (hereinafter referred to as a preprocessing reconstructed SPECT image). ). Then, as post-processing, the processing circuit 35 performs attenuation correction of the non-subject member 52 on the pre-processing reconstructed SPECT image.

In order to perform these pre-processing and post-processing, as shown in FIG. Implements the interpolation enlargement function 46 . Each of these functions 41 to 46 is stored in the storage circuit 33 in the form of a program.

First, preprocessing will be described. FIG. 5 shows a preprocessed reconstructed SPECT image (a SPECT image in which only the non-subject member is not subjected to attenuation correction) using an attenuation map that does not include the non-subject member 52 by the processor of the processing circuit 35 shown in FIG. is a flow chart showing an example of a procedure for executing preprocessing for generating .

In step S<b>1 , the acquisition function 41 acquires a preprocessing attenuation map that does not include the non-subject member 52 such as the headrest and the tabletop 21 in preprocessing. When creating an attenuation map from an MR image, since the original MR image itself does not include non-subject members, the created preprocessing attenuation map does not include non-subject members.

The preprocessing attenuation map is, for example, a value indicating air for the region of the non-subject member 52 in the X-ray CT image 51 (see left side of FIG. 4) including both the subject and the non-subject member 52— It is generated based on an image to which 1000 HU is allocated. The non-subject member 52 included in the X-ray CT image 51 used for preprocessing may be different from the non-subject member (SPECT non-subject member) used during SPECT imaging.

Next, in step S2, the attenuation correction map generation function 42 generates a preprocessing attenuation map that does not include the non-subject member 52 in preprocessing, and has the same size as the second size that is the effective field of view of the SPECT image. Enlarge and generate an attenuation correction map (attenuation correction coefficient image).

Next, in step S3, the reconstruction function 43 reconstructs the nuclear medicine projection data (SPECT projection data) of the subject based on the attenuation correction map generated from the preprocessing attenuation map in the preprocessing. , to generate preprocessed reconstructed SPECT images. In the preprocessing, the reconstruction function 43 can use various methods such as the Chang method, the Sorenson method, and the OS-EM method as attenuation correction methods. On the other hand, in post-processing, the reconstruction function 43 preferably performs attenuation correction using the Chang method.

By the above procedure, a preprocessing reconstructed SPECT image can be generated using an attenuation map that does not include the non-subject member 52 .

In preprocessing, the attenuation correction map used by the reconstruction function 43 is generated based on the preprocessing attenuation map that does not include non-subject members. Therefore, the preprocessing reconstructed SPECT image generated by the preprocessing is an image in which the influence of attenuation due to non-subject members is not corrected.

Next, post-processing will be described. FIG. 6 is a flow chart showing an example of the procedure when the processor of the processing circuit 35 shown in FIG. 1 executes post-processing for performing only attenuation correction of the non-subject member 52 on the pre-processed reconstructed SPECT image. This procedure starts when a preprocessed reconstructed SPECT image is generated by the procedure shown in FIG.

FIG. 7 is an explanatory diagram showing an example of the relationship between the effective field of view of the X-ray CT image (effective field of view of the attenuation map) and the effective field of view of the attenuation correction coefficient image in post-processing.

In the post-processing, the acquisition function 41 obtains a first An attenuation map (attenuation coefficient image) consisting of a reconstruction region 61 having a size of .

The attenuation map used in post-processing is based on an X-ray CT image 51 or a magnetic resonance image acquired by imaging a non-subject member used in SPECT imaging (hereinafter referred to as a non-subject member for SPECT imaging). generated or generated based on an image containing non-object parts for SPECT imaging generated by simulation. These images for generating the attenuation map used in post-processing need only include the non-subject member for SPECT imaging without lacking, and the subject does not have to be included.

It should be noted that the X-ray CT image 51, which is the original data of the preprocessing attenuation map acquired in step S4 of FIG. In the case of a non-subject member for use, an attenuation map for post-processing may be generated based on this X-ray CT image 51 .

In post-processing, the attenuation correction map generation function 42 generates an attenuation correction map 54 composed of the reconstruction area 61 of the first size based on the attenuation map composed of the reconstruction area 61 of the first size in step S12. (See center of FIG. 7).

Next, in step S13, the reception function 44 obtains information on obtaining a preprocessed reconstructed SPECT image consisting of the reconstruction area 62 of a second size (for example, 210 mm×210 mm) smaller than the reconstruction area of the first size. accept. The size of the reconstruction area (effective field of view) of the SPECT image is determined according to the imaging protocol, for example.

Next, in step S<b>14 , the extraction function 45 extracts a range corresponding to the reconstruction area 62 of the second size from the attenuation correction map 54 .

Next, in step S15, the interpolation enlargement function 46 interpolates and enlarges the attenuation correction map of the range extracted by the extraction function 45 based on the reconstruction area 61 of the first size and the reconstruction area 62 of the second size. (See FIG. 7 center and right).

Then, in the post-processing, the reconstruction function 43 uses the Chang method based on the attenuation correction map 60 (see the right side of FIG. 7) that has been interpolated and enlarged by the interpolation enlargement function 46 to generate a pre-process reconstructed SPECT image in step S16. The reconstruction produces a post-processed reconstructed SPECT image having a second size that is corrected for the effects of gamma ray attenuation by the non-subject material for the SPECT imaging. Specifically, in step S16, the reconstruction function 43 generates a post-process reconstructed SPECT image by multiplying the interpolation-enlarged attenuation correction map 60 by the pre-process reconstructed SPECT image.

Through the above procedure, the attenuation correction of the non-subject member for SPECT imaging can be performed on the preprocessed reconstructed SPECT image.

In addition, in the procedure shown in FIG. 7, the height of the non-subject member may be considered. For example, when the height of the headrest for SPECT imaging is different for each subject, after the process of step S13 and before the process of step S14, the attenuation correction map 54 and the preprocessed reconstructed SPECT image are aligned. do it. The attenuation map has a sharper contour of the non-subject member than the attenuation correction map and is suitable for alignment.

For this reason, the extraction function 45 first enlarges the attenuation map so as to align it with the preprocessed reconstructed SPECT image of the reconstruction region 62 of the second size, and then, in step S14, this enlargement Then, based on the positions of the attenuation maps that have been aligned, a range corresponding to the reconstruction region 62 of the second size may be extracted from the attenuation correction map. By aligning the attenuation correction map 54 with the preprocessed reconstructed SPECT image so as to consider the height of the subject member, the influence of attenuation due to the non-subject member can be corrected more accurately.

The nuclear medicine diagnostic apparatus 1 according to the present embodiment has a reconstruction area 61 having a size larger than the reconstruction area 62 of the SPECT image in post-processing, and from the attenuation map including the non-subject member used in SPECT imaging, An attenuation correction map 54 is acquired. Then, attenuation correction is performed using the attenuation correction map 60 obtained by interpolating and enlarging the range corresponding to the reconstruction area 62 of the SPECT image in the attenuation correction map 54 . Therefore, a nuclear medicine image in which the influence of attenuation due to non-subject members such as the headrest and the tabletop 21 outside the effective field of the attenuation map is corrected with high accuracy can be generated very easily. Therefore, the nuclear medicine diagnosis apparatus 1 according to the present embodiment can greatly improve the accuracy of diagnosis using quantitative values calculated from nuclear medicine images in nuclear medicine examinations.

Further, according to the attenuation correction method of the nuclear medicine diagnostic apparatus 1 according to the present embodiment, even if the reconstruction area of the nuclear medicine image is smaller than the reconstruction area of the attenuation map, a non-subject such as a headrest Artifacts due to truncation of members can be prevented. Therefore, the attenuation correction method according to this embodiment is suitable for a small-field gamma-ray detector. again,

(Second embodiment)
Next, a second embodiment of the nuclear medicine diagnostic apparatus 1 according to the present invention will be described.

FIG. 8 is a schematic block diagram showing an example of functions implemented by the processor of the processing circuit 35A of the nuclear medicine diagnostic apparatus 1 according to the second embodiment. The processing circuit 35A shown in the second embodiment uses a three-dimensional attenuation map (hereinafter referred to as a 3D attenuation map) and a three-dimensional attenuation correction map (hereinafter referred to as a 3D attenuation correction map) generated based on volume data. It differs from the processing circuit 35 shown in the first embodiment in that it Configurations that are not substantially different from those of the nuclear medicine imaging apparatus 1 shown in FIG.

As shown in FIG. 8, the processor of the processing circuit 35A implements an acquisition function 41A, an attenuation correction map generation function 42A, a reconstruction function 43A, an alignment function 71, and a correction function 72. FIG. Each of these functions is stored in the storage circuit 33 in the form of a program.

FIG. 9 shows the post-processing of performing attenuation correction of the non-subject member 52 using the 3D attenuation correction map on the pre-processing reconstructed SPECT image by the processor of the processing circuit 35A according to the second embodiment. It is a flow chart which shows an example of a procedure. This procedure starts when a preprocessed reconstructed SPECT image is generated by the procedure shown in FIG. Note that the preprocessing is the same as in the first embodiment, so the description is omitted.

First, in step S21, the acquisition function 41A acquires a 3D attenuation map consisting of a reconstruction region of a first size. This attenuation map is generated, for example, based on volume data including all non-subject members for SPECT imaging. Also in the second embodiment, the first size of the reconstruction area of the 3D attenuation map is larger than the second size of the reconstruction area of the preprocessed reconstructed SPECT image.

Next, in step S22, the attenuation correction map generation function 42A generates a 3D attenuation correction map made up of the reconstruction area of the first size based on the 3D attenuation map made up of the reconstruction area of the first size.

Next, in step S23, the registration function 71 three-dimensionally aligns the 3D attenuation map and the preprocessed reconstructed SPECT image by relatively shifting, rotating, etc. Get the alignment parameters.

Next, in step S24, the alignment function 71 three-dimensionally aligns the 3D attenuation correction map and the preprocessed reconstructed SPECT image with the acquired alignment parameters.

Next, in step S25, the correction function 72 corrects the data of the region where the influence of attenuation due to the non-subject member can be ignored among the three-dimensionally aligned 3D attenuation correction maps to 1.0. This is to prevent the attenuation correction of the portion coming from the area without data. When the 3D attenuation correction map and the preprocessed reconstructed SPECT image are multiplied, the portion multiplied by 1.0 in the preprocessed reconstructed SPECT image is not subjected to attenuation correction and the data of the original SPECT image is maintained. will be

Next, in step S26, the reconstruction function 43A reconstructs the pre-process reconstructed SPECT image to generate a post-process reconstructed SPECT image based on the registered 3D attenuation correction map.

Through the above procedure, the attenuation correction of the non-subject member 52 can be performed on the preprocessed reconstructed SPECT image using the 3D attenuation correction map.

The nuclear medicine diagnostic apparatus 1 according to the second embodiment also has the same effect as the first embodiment. Further, the nuclear medicine diagnosis apparatus 1 according to the second embodiment aligns the 3D attenuation correction data based on the volume data and the preprocessing reconstructed SPECT image to perform attenuation correction. Therefore, even if the position and shape of a non-subject member such as a headrest are different for each slice of the preprocessing reconstructed SPECT image, the influence of attenuation of the non-subject member can be corrected easily and accurately. . That is, compared to the nuclear medicine diagnostic apparatus 1 according to the first embodiment, in which the position of a non-subject member such as a headrest is determined and the enlarged attenuation correction map is simply multiplied, the nuclear medicine diagnostic apparatus according to the second embodiment is used. According to 1, by creating an attenuation correction map by shifting, rotating, etc. or linearly interpolating the attenuation correction map, for example, by adjusting the height of the position of the headrest, the attenuation of the non-subject member can be accurately performed. effects can be corrected.

In addition, the non-subject member 52 such as the top plate and headrest of the X-ray CT apparatus should be deleted from the X-ray CT image, and the image of the non-subject member for SPECT imaging should be pasted on the X-ray CT image. For example, it is possible to suppress the influence caused by the structural difference between the nuclear medicine diagnostic apparatus 1 and the non-subject member 52 such as the top plate and the headrest of the X-ray CT apparatus.

According to at least one embodiment described above, it is possible to generate a nuclear medicine image in which the influence of attenuation due to non-subject members outside the effective field of view of the attenuation map is corrected.

Acquisition functions 41 and 41A of processing circuits 35 and 35A in this embodiment, attenuation correction map generation functions 42 and 42A, reconstruction functions 43 and 43A, reception function 44, extraction function 45, interpolation enlargement function 46, and alignment function 71 and correction function 72 are examples of an acquisition unit, a generation unit, a reconstruction unit, a reception unit, an extraction unit, an interpolation enlargement unit, an alignment unit, and a correction unit, respectively, in the claims.

In the above embodiment, the word "processor" is, for example, a dedicated or general-purpose CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or an application specific integrated circuit (ASIC), Circuits such as programmable logic devices (eg, Simple Programmable Logic Devices (SPLDs), Complex Programmable Logic Devices (CPLDs), and FPGAs) shall be meant. The processor implements various functions by reading and executing programs stored in the storage medium.

Further, in the above embodiments, an example of a case where a single processor of the processing circuit realizes each function is shown, but a processing circuit is configured by combining a plurality of independent processors, and each processor realizes each function. good too. Further, when a plurality of processors are provided, a storage medium for storing programs may be provided individually for each processor, or a single storage medium may collectively store programs corresponding to the functions of all processors. good too.

It should be noted that although several embodiments of the invention have been described, these embodiments are provided by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

1 nuclear medicine diagnosis apparatus 35, 35A processing circuits 41, 41A acquisition functions 42, 42A attenuation correction map generation functions 43, 43A reconstruction function 44 reception function 45 extraction function 46 interpolation enlargement function 51 X-ray CT image 52 non-subject member 53 X-ray CT image 54 attenuation correction map 60 interpolation-enlarged attenuation correction map 61 reconstruction region of first size 62 reconstruction region of second size 71 registration function 72 correction function

Claims (5)

an acquisition unit that acquires an attenuation coefficient image consisting of a reconstruction region of a first size having an effective field of view of a non-subject member for SPECT without truncation taken by an X-ray CT apparatus;
a generation unit that generates an attenuation correction coefficient image consisting of the reconstruction area of the first size based on the attenuation coefficient image;
A reception unit that receives information on acquisition of a nuclear medicine image of a second size reconstruction area having an effective field of view of SPECT acquisition data smaller than the first size reconstruction area;
an extraction unit for extracting a range corresponding to the reconstruction area of the second size from the attenuation correction coefficient image;
an interpolation enlargement unit that interpolates and enlarges the extracted attenuation correction coefficient image of the range based on the reconstruction area of the first size and the reconstruction area of the second size ;
A reconstruction unit that reconstructs a nuclear medicine image of the reconstruction area of the second size based on the interpolation-enlarged attenuation correction coefficient image to generate a second nuclear medicine image;
with
The reconstruction unit
As preprocessing, a nuclear medicine image of the reconstruction area of the second size is generated by reconstructing nuclear medicine projection data of the subject based on the preprocessing attenuation correction coefficient image that does not include non-subject members. Along with, as post-processing, the generated nuclear medicine image of the reconstruction area of the second size, reconstructed based on the interpolation-enlarged attenuation correction coefficient image to generate the second nuclear medicine image,
Nuclear medicine diagnostic equipment. The acquisition unit
Acquiring the attenuation coefficient image generated based on an image including the non-subject member generated by simulation, or an X-ray CT image or magnetic resonance image acquired by imaging the non-subject member;
The nuclear medicine diagnostic apparatus according to claim 1 . The non-subject member is a headrest or a top plate used in capturing a nuclear medicine image of the subject,
The nuclear medicine diagnostic apparatus according to claim 1 or 2 . The extractor is
magnifying the attenuation coefficient image to align the attenuation coefficient image with respect to a nuclear medicine image of the second size reconstruction region; based on the position of the magnified and aligned attenuation coefficient image, extracting the range corresponding to the reconstruction area of the second size from the attenuation correction coefficient image;
The nuclear medicine diagnostic apparatus according to any one of claims 1 to 3 . an acquisition unit configured to acquire a three-dimensional attenuation coefficient image, which is an attenuation coefficient image including a reconstruction area of a first size and generated based on the volume data;
a generation unit that generates a three-dimensional attenuation correction coefficient image consisting of the reconstruction area of the first size based on the three-dimensional attenuation coefficient image;
Aligning the three-dimensional attenuation coefficient image and the nuclear medicine image in three dimensions, and aligning the three-dimensional attenuation correction coefficient image and the nuclear medicine image with the alignment parameters used for alignment Department and
A reconstruction unit that reconstructs the nuclear medicine image to generate a second nuclear medicine image based on the aligned three-dimensional attenuation correction coefficient image;
with
The reconstruction unit
Reconstruction of a second size smaller than the reconstruction region of the first size by reconstructing nuclear medicine projection data of the subject based on the preprocessing attenuation correction coefficient image that does not include non-subject members. generate a nuclear medicine image of the region,
A correction unit that corrects data in a region where the influence of attenuation by the non-subject member can be ignored in the aligned three-dimensional attenuation correction coefficient image to 1;
further comprising
The reconstruction unit
The second nuclear medicine image is generated by reconstructing a nuclear medicine image of the reconstruction area of the second size based on the three-dimensional attenuation correction coefficient image aligned and corrected by the correction unit. do,
Nuclear medicine diagnostic equipment.

Images