JP2004045318A - Nuclear medicine diagnostic system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nuclear medicine diagnostic system that can readily and easily obtain an excellent image by correcting the influence of the body movement of a subject caused by breathing by processing data acquired at photographing time with software without using such a device as the breath monitor etc. <P>SOLUTION: While this nuclear medicine diagnostic device performs image data collection based on the detection of radiation from a subject (step 1), the device sets a region of interest at a location where the change of the count value of the radiation becomes larger due to breathing in the image obtained through the collection (step 2). Then the device counts the count value of the radiation in the region of interest (step 3) and prepares a variation curve showing the temporal variation of the count value (step 4). In addition, the system divides the image data corresponding to the variation curve at every phase by dividing the variation curve into a plurality of phases (step 5). Thereafter, the system prepares images for each phase by adding image data for each phase (step 5) and displays the images on a screen (step 6). <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a nuclear medicine diagnostic apparatus capable of obtaining a favorable image by reducing the influence of respiratory movement of the subject when imaging the chest and abdomen of the subject.
[0002]
[Prior art]
Conventionally, a drug labeled with a radioisotope (hereinafter, referred to as “RI”) is administered into a subject, and gamma rays emitted from the RI are detected and measured based on the result of the detection and measurement. There has been provided a nuclear medicine diagnostic apparatus for imaging a state of distribution in a specimen. In order to obtain the image as a predetermined tomographic image, a gamma camera (a camera that detects a gamma ray and captures a two-dimensional distribution of RI) is used as a detector, and the gamma camera is used as an axis with respect to the body axis of the subject. 2. Description of the Related Art A device that rotates 360 degrees to perform photographing (see FIG. 8), a so-called SPECT (Single Photon Emission Computed Tomography) device is widely known.
[0003]
However, in a nuclear medicine examination performed using a nuclear medicine diagnostic apparatus including this SPECT apparatus, since it takes several minutes for imaging, an image obtained by imaging is affected by body movement due to respiration of the subject. In particular, in imaging of the chest and abdomen of the subject, there is a problem that the contrast of the image is significantly reduced due to the effect of body movement due to respiration.
[0004]
Therefore, in a conventional magnetic resonance apparatus, X-ray CT tomography apparatus, or the like, when performing imaging on the chest or abdomen of the subject, the subject stops breathing and performs data collection, or A technique of detecting a respiratory motion and taking an image in synchronization with a period in which the respiratory motion is stable has been adopted.
[0005]
However, in order to implement such a method, a device such as a respiratory monitor for detecting the respiratory movement of the subject is required, and this causes problems such as an increase in cost and an increase in the size of the device.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and an object thereof is to provide a respiratory monitor or the like for detecting a respiratory motion of a subject when performing imaging on a chest or abdomen of the subject. Nuclear medicine that can easily and easily obtain good images by correcting the effects of body movement due to respiration of the subject by processing the data obtained at the time of imaging on software without using an apparatus It is to provide a diagnostic device.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 detects a radiation emitted from a subject and creates an image related to the subject from an image data group based on a detection result of the radiation. A radiation detecting means for detecting radiation emitted from the subject; a first image producing means for producing an image from an image data group based on a detection result from the radiation detecting means; A region-of-interest setting unit that sets a region of interest in an image created by the unit; a measuring unit that measures a count value of radiation in the region of interest of the image set by the region of interest setting over time; A phase classifying unit that classifies the image data group for each predetermined phase in accordance with a temporal change in the count value of the radiation from the measuring unit; and And having a second image forming means for forming an image of each of the phase based on class been said image data group.
[0008]
In order to solve the above problem, the invention according to claim 2 forms an image from a radiation detection unit for detecting radiation emitted from a subject and an image data group based on a detection result from the radiation detection unit. First image creating means for setting, a region of interest setting means for setting a region of interest in an image created by the image creating means, and a region of interest of the image set by the region of interest setting means Measuring means for measuring the radiation count value over time, and a phase for classifying the image data group for each predetermined phase according to a temporal change in the radiation count value from the measuring means. A classification unit; a second image generation unit for generating an image for each phase based on the image data group classified by the phase classification unit; and the radiation detection unit. Detecting radiation from the subject, creating an image from a group of image data based on the detection result from the radiation detecting means by the first image creating means, and creating an image of interest in the image by the region of interest setting means. A region is set, and the count value of the radiation in the region of interest is measured with the lapse of time by the measurement unit, and the image data group is determined by the phase classification unit in accordance with a temporal change in the count value of the radiation. Control means for performing control for creating an image for each phase based on the image data group classified for each phase by the second image creating means. It is characterized by that.
[0009]
In order to solve the above-mentioned problem, the invention according to claim 3 is the nuclear medicine diagnostic apparatus according to claim 1 or 2, wherein the region of interest setting means is configured to perform the respiratory movement of the subject. The region of interest is set at a specific portion where the temporal change of the radiation count value is large.
[0010]
According to a fourth aspect of the present invention, there is provided a nuclear medicine diagnostic apparatus according to the third aspect, wherein the specific portion is a lower lung.
[0011]
In order to solve the above-mentioned problem, the invention according to claim 5 is the nuclear medicine diagnostic apparatus according to claim 1 or 2, wherein the phase classification unit determines a temporal change in the count value of the radiation. Displacement curve creation means for creating a displacement curve to represent, and a phase division means for dividing the displacement curve into a plurality of phase groups by dividing the displacement curve by a predetermined number for each respiratory cycle of the subject, Image data classifying means for classifying the image data group for each phase corresponding to the phase group.
[0012]
In order to solve the above problem, the invention according to claim 6 is the nuclear medicine diagnostic apparatus according to claim 5, further comprising a division number setting unit for arbitrarily setting the predetermined number. And
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a nuclear medicine diagnostic apparatus according to the present invention will be described in detail with reference to the drawings.
[0014]
[Configuration of nuclear medicine diagnostic device]
FIG. 1 is a perspective view illustrating an entire configuration of a nuclear medicine diagnostic apparatus according to the present embodiment. As shown in the figure, the nuclear medicine diagnostic apparatus mainly includes a bed 1 on which a subject P is placed, a gantry 2 supporting a detector 22, and a bed 1 for operating the gantry 1 and the gantry 2. And an operation console 3.
[0015]
The couch 1 includes a top plate 11 on which the subject P is placed, and support portions 12 and 13 which support the subject P at both ends. The support parts 12 and 13 move the top plate 11 up and down freely by driving in synchronization with each other.
[0016]
The gantry 2 includes a fixed base 24 placed on the floor rail 4, a rotating ring 23 rotatably fitted to the fixed base 24, and supported on the inner surface of the rotating ring 23, and the top plate 11 of the bed 1. The detector 22 (detector main body 21) for detecting radiation emitted from the subject P mounted thereon, that is, gamma rays. The rotating ring 23 freely rotates along the circumferential direction A in FIG. Further, the fixed base 24 moves in parallel on the floor rail 4 along the body axis Z of the subject P. The exchange of signals, power supply, and the like between the fixed base 24 and the rotary ring 23 is performed via a cable.
[0017]
In the detector main body 21, a plurality of semiconductor detection elements such as CdTe or CdZnTe are arranged in a two-dimensional array. A collimator is provided on the entire surface of the array structure where the gamma rays enter, and limits the detected gamma rays to a specific direction.
[0018]
Note that the detector 22 and the detector main body 21 may be configured using a scintillator and a photomultiplier.
[0019]
The operation console 3 includes an operation panel 31 for performing operations related to the support portions 12 and 13 of the bed 1 and the rotating ring 23 and the fixed base 24 of the gantry 2, a display monitor 32 for displaying an image of the subject P, and the like. In the image of the subject P displayed on the monitor 32, a mouse 33 is used for performing an operation of setting a region of interest and the like.
[0020]
In such a configuration, the subject P placed on the top plate 11 of the bed 1 moves its body axis Z by the rotation of the rotating ring of the gantry 2 by raising and lowering the support portions 12 and 13 by operating the operation panel 31. After being substantially aligned with the axis, a predetermined radioisotope is administered, and gamma rays emitted from the radioisotope are detected by the detector 22 (detector main body 21). The detector 22 (detector main body 21) is fixed at a predetermined position according to the test, or is translated along the body axis Z of the subject P, There is a case where it is rotated around. Incidentally, in a lung examination described later, the detector 22 (detector main body 21) is fixed at a predetermined position.
[0021]
FIG. 2 is a block diagram illustrating a control configuration of the nuclear medicine diagnostic apparatus. As shown in the figure, the nuclear medicine diagnostic apparatus mainly includes a central processing unit (CPU) 100 that controls each unit, and an image data creating apparatus 200 that creates image data based on a detection result from the detector 22. A data collection memory 300 that is a primary storage unit of the image data, an image creation unit 400 that performs an image process for creating an image based on the image data, and a storage unit for an image after the image processing. A certain disk unit 500, a region-of-interest setting unit 600 that sets a region of interest in an image displayed on the display monitor 32, a radiation counter 700 that measures the number of radiations in the region of interest over time, The image data stored in the data acquisition memory 300 is divided for each phase according to the temporal change of the radiation count value by the radiation counter 700. Phase as the dividing unit 800, the phase dividing section 800 by the adding processing image data of each divided phase, and an the image creating unit 400. To create an image for each phase.
[0022]
Note that the CPU 100, the data acquisition memory 300, the image creation unit 400, the disk unit 500, the region of interest setting unit 600, the radiation counter 700, the phase division unit 800, and the like are usually integrated as one computer system.
[0023]
Further, the disk unit 500 includes a predetermined imaging operation program that can be selectively used by an operator in accordance with various types of imaging, and, as described later, when performing imaging on the chest and abdomen of the subject, An operation program and the like for performing a series of processes for creating an image in which the influence of body movement due to respiration of the subject is corrected based on image data obtained at the time of imaging are stored. 31 or the mouse 33, and the CPU 100 performs various arithmetic processes while controlling each unit according to the contents of the program. For example, the CPU 100 detects the top plate 11 and the detector 22 when acquiring image data. A process for setting a position, a detection direction, and the like, and a series of processes for creating an image in which the influence of body movement due to respiration of the subject, which will be described later, is corrected are performed.
[0024]
As described above, under the control of the CPU 100, the detection result of the gamma ray by the detector 22 is transmitted to the image data creation device 200, and the image data creation device 200 creates image data based on the detection result. After the image data is stored in the data collection memory 300 as a storage unit, the image data is transmitted from the data collection memory 300 to the image creation unit 400. The image creating unit 400 performs an image creating process based on the image data transmitted from the data collection memory 300, and displays an image as a result of the process on the display monitor 32. At the same time, the images are stored on the disk unit 500.
[0025]
[Operation of the nuclear medicine diagnostic apparatus]
Next, the operation of the nuclear medicine diagnostic apparatus described above will be described with reference to the flowchart shown in FIG.
[0026]
Note that a series of processes described below for creating an image in which the effect of body movement due to respiration of the subject has been corrected is performed under the control of the CPU 100.
[0027]
The operator first moves the supports 12 and 13 of the bed 1 and the rotating ring 23 and the fixed base 24 of the gantry 2 by operating the operation panel 31 to fix the detector 22 at a desired position. A drug labeled with a radioisotope is administered to the subject P placed on the plate 11, and gamma rays emitted from the radioisotope are detected (step 1). At this time, the detector 22 repeatedly detects a gamma ray at a fixed time interval (a fraction of the respiratory body movement cycle of the subject). The detection result is transmitted from the detector 22 to the image data creation device 200, and the image data creation device 200 creates image data based on the detection result. The image data is stored in the data collection memory 300 as a storage means, and is transmitted to the image creating unit 400. As shown in FIG. 4, the image creating unit 400 sequentially performs image processing based on the image data transmitted from the image data creating apparatus 200 to create a plurality of images. Further, one of the plurality of images, for example, the first one, is displayed on the display monitor 32 of the operation console 3. At this time, the plurality of images are stored in the disk unit 500 as the storage means. Note that, in the present embodiment, the case where a lung test is performed is described as an example, and thus the image displayed on the display monitor 32 relates to the lungs of the subject.
[0028]
Next, the operator sets the region of interest ROI by operating the mouse 33 in the image on the display monitor 32 (step 2). The setting of the region of interest ROI is the same as the setting method in the conventional nuclear medicine diagnostic apparatus. However, the set position is a portion that is easily affected by body motion due to respiration of the subject P. Specifically, as shown in FIGS. 5 (a) and 5 (b), it is set near the diaphragm for expanding and contracting the lung Q during breathing, that is, below the lung Q. Hereinafter, the reason will be described.
[0029]
When the region of interest ROI is set in the lower part of the lung Q, as shown in FIG. 3A, for example, when the lung Q is in the transition from the inspiratory phase to the expiratory phase and is in the most expanded state, Most of the lower region of the lung will be located in the region of interest ROI. On the other hand, as shown in FIG. 2B, for example, when the lung Q is in the transition from the expiratory phase to the inspiratory phase and is in the most contracted state, the lower area of the lung Q is almost completely within the region of interest ROI. Will no longer be located. Here, the inspiratory phase refers to a period during which the subject P is inhaling, and the expiratory phase refers to a period during which the subject P is exhaling. Then, when the radiation in the region of interest ROI is counted by the radiation measurement counter 700 described later, the count value greatly increases and decreases. Specifically, during the period when the lung Q is in the expiratory phase, the radiation count value is greatly increased, while when the lung Q is in the inspiratory phase, the radiation count value is greatly reduced. By setting the region of interest ROI in the lower part of the lung Q in this manner, the count value of the radiation in the region of interest ROI by the radiation measurement counter 700 is greatly increased or decreased. Phase, a state in the expiration phase, a state in the transition from the expiration phase to the inspiration phase, a state in the inspiration phase, etc.) and the displacement of the radiation count value by the radiation measurement counter 700 can be finely correlated. By grasping the displacement of the count value of the radiation counted in the region of interest ROI, the state of the lung Q can be accurately grasped. This is the reason for setting the region of interest ROI below the lung Q.
[0030]
The setting information on the region of interest ROI is transmitted to the region of interest setting unit 600, and the setting contents are reflected. Further, the shape of the region of interest ROI is not limited to a square shape, and may be, for example, a polygonal shape, a circular shape, an elliptical shape, or the like.
[0031]
The radiation measurement counter 700 measures the count value of radiation (gamma rays) in the region of interest ROI every time image data is created, in synchronization with the detection of gamma rays by the detector 22. At this time, the image data is stored in the data acquisition memory 300 after the image data and the count value are associated with each other. Then, the phase dividing unit 800 creates a displacement curve U, for example, as shown in FIG. 6 representing the temporal change, and displays this on the display monitor 32 of the operation console 3 (step 3). The portion from the maximum value to the minimum value of the displacement curve U shown in the figure corresponds to the expiratory phase R, and the portion from the minimum value to the maximum value corresponds to the inspiratory phase S. In addition, a set T of the expiratory phase R and the inspiratory phase S constitutes a cycle T of the respiratory body movement.
[0032]
Next, on the setting screen (not shown) of the display monitor 32, the operator performs a setting to divide each cycle T of the displacement curve U into a plurality of phases by operating the mouse 33. Hereinafter, a specific method of dividing the displacement curve U into a plurality of phases will be described.
[0033]
The phase dividing unit 800 grasps the minimum value (the minimum value 1 to the minimum value (n + 1)) and the maximum value (the maximum value 1 to the maximum value (n + 2)) in the displacement curve U, and then, as shown in FIG. For each cycle T, a portion from the minimum value to the maximum value (inspiratory phase A) and a portion from the maximum value to the minimum value (expiration phase B) are divided by a predetermined number. Incidentally, in this example, the predetermined number is set to “2”, and the portion from the minimum value to the maximum value (inspiratory phase R) and the portion from the maximum value to the minimum value (expiration phase S) are each two. Is divided into
[0034]
The operator can arbitrarily set the predetermined number at this time. Specifically, on the setting screen (not shown) displayed on the display monitor 32, the specific number ( A predetermined number is set, and the setting content is reflected in the above-described phase division processing of the phase division section 800 (step 4).
[0035]
Then, the image creating section 400 calls out the image data corresponding to each phase divided into the predetermined number, that is, the count value of each radiation (gamma ray) from the data collection memory 300 in which the data is accumulated, and further, An image for each phase is created by performing the addition process (step 5). That is, in the case of this example, the image data corresponding to each of the phase a, the phase a ′, and the phase a ″ shown in FIG. An image A at the time of transition from the inspiratory phase S to the expiratory phase R shown in FIG. 8 is created. Similarly, image data corresponding to each of phase b, phase b ′, and phase b ″ shown in FIG. 7 is called from the data collection memory 300, and these are added to each other, whereby the expiratory phase shown in FIG. An image B in R is created. Similarly, the image data corresponding to each of the phase c, the phase c ′, and the phase c ″ shown in FIG. 7 is called from the data collection memory 300, and these are added, so that the expiration phase shown in FIG. An image C at the time of transition from R to the intake phase S is created. Similarly, the image data corresponding to each of the phase d, the phase d ′, and the phase d ″ shown in FIG. 7 is called from the data acquisition memory 300, and these are added, so that the intake phase shown in FIG. An image D in S is created.
[0036]
The images A to D for each phase created in this way are stored in the disk unit 500 and displayed on the display monitor 32 (step 6). The display form of the images A to D at this time may be, for example, an image in which the images A to D are sequentially arranged and displayed at the same time. Only A is displayed, and by operation of the mouse 33, an image B in the expiratory phase R, an image C in transition from the expiratory phase R to the inspiratory phase S, an image D in the inspiratory phase S, and the like are sequentially displayed. May be.
[0037]
All of the images A to D for each phase displayed on the display monitor 32 are created by adding image data for each phase in synchronization with the period T of the respiratory movement of the subject P. Therefore, the influence of the respiratory movement of the subject P is reduced. Therefore, the images A to D for each phase do not have a problem such as a decrease in contrast, and are extremely good images.
[0038]
By the way, as shown in FIG. 8, the conventional image O is created by adding all the image data serving as the constituent elements of these images A to D. For example, the images A to D in each phase are superimposed, resulting in a blurred image as a whole, and at the same time, a problem such as a decrease in contrast occurs.
[0039]
As described above, according to the nuclear medicine diagnostic apparatus of the present embodiment, when performing imaging on the chest and abdomen of the subject, without using a device such as a respiratory monitor that detects the respiratory motion of the subject. Since it is possible to create an image in which the influence of body movement due to respiration is corrected by processing on software, it is possible to easily and easily obtain a good image without problems such as a decrease in contrast. .
[0040]
Note that the nuclear medicine diagnostic apparatus according to the present invention is not limited to the form of the nuclear medicine diagnostic apparatus in the present embodiment described above. For example, the bed 1, the gantry 2, the operation console 3, and the floor of the apparatus may be used. The configuration of the rails 4 and the like may adopt another configuration. In addition, the shape, the setting position, and the like of the region of interest ROI may be appropriately set according to the examination target site (the chest, the abdomen, and the like). Further, the predetermined value when dividing the displacement curve U into each phase by the phase dividing unit 800 may be a fixed value in order to save the trouble of setting. Furthermore, when the phase dividing unit 800 divides the displacement curve U into each phase, for example, the radiation count value of the radiation measurement counter 700 may be used as a reference instead of using the cycle as a reference. Even in such a case, a good image can be obtained similarly.
[0041]
【The invention's effect】
As described above, according to the nuclear medicine diagnostic apparatus of the present invention, when performing imaging on the chest and abdomen of the subject, a device such as a respiratory monitor that detects the respiratory motion of the subject is used. Without processing, the image data obtained at the time of imaging can be processed on software to correct the effect of body movement due to respiration of the subject, and an image can be created. A good image can be obtained simply and easily without the occurrence of the image.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram showing an overall configuration of an embodiment of a nuclear medicine diagnostic apparatus according to the present invention.
FIG. 2 is a block diagram showing a control configuration of the nuclear medicine diagnostic apparatus shown in FIG.
FIG. 3 is a flowchart for explaining a flow of an image creation process in the nuclear medicine diagnostic apparatus shown in FIG. 1;
FIG. 4 is an explanatory diagram for explaining a method of setting a region of interest in the nuclear medicine diagnostic apparatus shown in FIG.
FIG. 5 is an explanatory diagram for explaining a method of setting a region of interest in the nuclear medicine diagnostic apparatus shown in FIG.
6 is a diagram showing a displacement curve representing a temporal change of a radiation count value in a region of interest displayed on a display monitor of the nuclear medicine diagnostic apparatus shown in FIG.
FIG. 7 is an explanatory diagram for explaining a method of dividing the displacement curve shown in FIG. 6 into each phase.
8 is an explanatory diagram for explaining a difference between an image for each phase displayed on the display monitor of the nuclear medicine diagnostic apparatus shown in FIG. 1 and a conventional image.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Bed 11 ... Top plate 12, 13 ... Support part 2 ... Stand 21 ... Detector main body 22 ... Detector 23 ... Rotating ring 24 ... Fixed table 3 ... Operation console 31 ... Operation panel 32 ... Display monitor 33 ... Mouse 4 ... Floor rail 100 CPU
200 image data creation unit 300 data acquisition memory 400 image creation unit 500 disk unit 600 region of interest setting unit 700 radiation counter 800 phase division units ad to phase a 'to d' phase a '' ... D ″... Phase A... Image at the transition from the inspiratory phase to the expiratory phase B... Image C at the transition from the expiratory phase to the inspiratory phase D. P ... Subject Q ... Lung R ... Expiratory phase S ... Inspiratory phase T ... Respiratory motion cycle U ... Displacement curve

Claims (6)

A nuclear medicine diagnostic apparatus that detects radiation emitted from a subject and creates an image related to the subject from an image data group based on the detection result of the radiation,
Radiation detection means for detecting radiation emitted from the subject,
First image creating means for creating an image from an image data group based on a detection result from the radiation detecting means;
A region of interest setting means for setting a region of interest in an image created by the image creating means,
A measuring unit that measures a count value of radiation in the region of interest of the image set by the region of interest setting unit over time,
Phase classification means for classifying the image data group for each predetermined phase according to a temporal change in the count value of the radiation from the measurement means,
A second image creating means for creating an image for each phase based on the image data group classified by the phase classifying means. Radiation detection means for detecting radiation emitted from the subject,
First image creating means for creating an image from an image data group based on a detection result from the radiation detecting means;
A region of interest setting means for setting a region of interest in an image created by the image creating means,
Measurement means for measuring the count value of radiation in the region of interest of the image set by the region of interest setting means over time,
Phase classification means for classifying the image data group for each predetermined phase according to a temporal change of the radiation count value from the measurement means,
A second image creating unit for creating an image for each phase based on the image data group classified by the phase classifying unit;
The radiation detecting means detects radiation from the subject, the first image creating means creates an image from an image data group based on the detection result from the radiation detecting means, and the region of interest setting means A region of interest is set in the image, the count value of the radiation in the region of interest is measured over time by the measurement unit, and the phase classification unit calculates the count value of the radiation according to the temporal change. Control means for classifying the image data group for each predetermined phase, and performing control for creating an image for each phase based on the image data group classified for each phase by the second image creation means; A nuclear medicine diagnostic apparatus characterized by comprising: 3. The region of interest according to claim 1, wherein the region of interest setting unit sets the region of interest in a specific portion where a temporal change in the count value of the radiation increases due to a respiratory movement of the subject. Nuclear medicine diagnostic equipment. The nuclear medicine diagnostic apparatus according to claim 3, wherein the specific portion is a lower part of a lung. The phase classification means,
Displacement curve creating means for creating a displacement curve representing the temporal change of the radiation count value,
Phase dividing means for dividing the displacement curve into a plurality of phase groups by dividing the displacement curve by a predetermined number for each respiratory cycle of the subject,
The nuclear medicine diagnostic apparatus according to claim 1, further comprising: an image data classification unit configured to classify the image data group for each phase corresponding to the phase group. The nuclear medicine diagnostic apparatus according to claim 5, further comprising a division number setting unit for arbitrarily setting the predetermined number.

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