JP2004305487A - Image processing apparatus, method and system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate images effective for a diagnosis based on dynamic images. <P>SOLUTION: A continuous image acquisition unit 5 continuously acquires a plurality of X-ray images in a time series to be stored into a storage device 7. A cross section generation indicating UI unit 9 sets lines at desired positions for each of a plurality of the X-ray images. A cross section generation unit 10 acquires pixel rows arrayed along the set lines from each of a plurality of the X-ray images to be arranged in the time series sequence thereby generating new images. A cross section display unit 11 displays these new images. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image processing technique, and more particularly to an image processing technique suitable for processing a radiographic image in the medical field.
[0002]
[Prior art]
The technique of imaging the transmission intensity distribution using the material transmission ability of radiation represented by X-rays is the basis of the development of modern medical technology. Since the discovery of X-rays, a method of converting the X-ray intensity distribution into visible light using a phosphor, forming a latent image on a silver halide film, and developing the image has been adopted for imaging the intensity distribution. In recent years, when a X-ray image is digitized, a stimulable phosphor is used, and a latent image as a stored energy distribution on the stimulable phosphor due to X-ray irradiation is excited by a laser beam and read out to be digitally imaged. A method using a so-called imaging plate has also been generalized. Furthermore, with the advancement of semiconductor technology, a large-sized solid-state image sensor capable of covering the size of the human body, a so-called flat panel detector, has also been developed to directly digitize an X-ray image without creating a latent image so that efficient diagnosis can be performed. It has become
[0003]
On the other hand, it is also possible to use an image pickup device represented by a photomultiplier tube (image intensifier) to image fluorescent light due to weak X-rays and observe dynamics inside a human body, and it has been generally used. ing. Modern flat panel detectors have sensitivity comparable to such image intensifiers, and are capable of capturing dynamics over a wide range of the human body.
[0004]
Generally, the most effective medical X-ray imaging is a chest imaging of a human body. Since radiographing a large area of the chest including the abdomen is useful for finding many diseases including lung diseases, chest X-ray imaging has become indispensable in a normal medical examination. In addition, in order to efficiently diagnose a huge amount of chest X-ray images taken for a health check in recent years, image analysis is performed on a chest digital X-ray image using a computer to assist a doctor in the initial diagnosis. The so-called computer-aided diagnosis (CAD) is also being put to practical use.
It should be noted that an abnormal shadow detection device that detects an abnormal shadow appearing in a radiographic image is known from Patent Documents 1 and 2.
[0005]
[Patent Document 1]
Japanese Patent No. 2582665 [Patent Document 2]
Japanese Patent No. 2582666 [0006]
[Problems to be solved by the invention]
By the way, when it is found that a certain disease is suspected by chest X-ray photography or the like in the medical examination, a definitive diagnosis is performed by a so-called precision diagnosis. In such a precise diagnosis, CT and MR scans are often performed. These CT scans and MR scans require several times the cost of diagnosis as compared to normal X-ray imaging. In many cases, such an accurate diagnosis is an erroneous diagnosis in the early stage and there is no disease, but such a misdiagnosis consumes unnecessary medical expenses and contributes to a rise in medical expenses. . To prevent this, it is important to improve the accuracy of the health checkup, which is the initial checkup.
[0007]
As a method of improving the accuracy of diagnosis while suppressing an increase in cost, it is effective to acquire a moving image of the chest showing the movement by respiration or the like using the above-described large-sized flat panel detector and to observe the movement. In the dynamic observation, unlike the conventional case of observing a still image, the image is switched and observed in time series. However, such dynamic observation often depends on the subjectivity of the observer as compared with still image observation, and vague points tend to remain. In addition, a large amount of observation time is consumed, and the efficiency of diagnosis is low.
[0008]
The present invention has been made in view of the above problems, and has as its object to generate an image effective for diagnosis based on a dynamic image.
[0009]
[Means for Solving the Problems]
An image processing apparatus according to the present invention for achieving the above object has the following configuration. That is,
Acquisition means for acquiring, from each of the plurality of images constituting the dynamic image of the target object, a pixel array arranged along a set straight line,
Generating means for generating an image based on a plurality of pixel rows obtained from the plurality of images by the obtaining means.
Further, according to the present invention, there is provided a system including the image processing device and the imaging device.
An image processing apparatus according to another aspect of the present invention for achieving the above object has the following configuration. That is,
From each of the plurality of images constituting the dynamic image of the object, an acquisition step of acquiring a pixel row aligned along a set straight line,
A generating step of generating an image based on a plurality of pixel columns obtained from the plurality of images in the obtaining step.
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
[0010]
[First Embodiment]
In order to solve the above-mentioned problem, in the present embodiment, a dynamic image (in this embodiment, a respiratory dynamic image) continuously acquired in time series is converted into a "spatio-temporal three-dimensional image" And a cross-sectional image and a sagittal plane thereof are created and displayed so as to be observable. This allows static observation and analysis of dynamic images and, consequently, medical image images.
[0011]
FIG. 1 is a block diagram schematically showing the configuration of the respiratory dynamic imaging apparatus according to the first embodiment. In FIG. 1, reference numeral 1 denotes an X-ray image sensor for imaging an X-ray intensity, and is capable of continuously acquiring an image. As the X-ray image sensor 1, a flat panel detector can be used. An X-ray generator 2 generates X-rays and irradiates the X-rays to the subject. Reference numeral 3 denotes a control device which controls the X-ray image sensor 1 and the X-ray generation device 2 to properly synchronize X-ray generation and image acquisition. Reference numeral 4 denotes a human body as a subject (subject).
[0012]
Reference numeral 5 denotes a continuous image acquisition unit which continuously acquires image data output from the X-ray image sensor 1. Reference numeral 6 denotes a moving image display unit which displays a chest image of a human body continuously acquired by the continuous image acquisition unit 5 on a display in real time. Reference numeral 7 denotes a storage device that stores the images acquired by the continuous image acquisition unit 5. The moving image display unit 6 can extract data from the storage device 7 at any time and sequentially refer to the data. That is, the moving image display unit 6 can display a moving image in real time, or a continuously acquired image such as a recorded and reproduced image as a moving image later.
[0013]
Reference numeral 8 denotes a spatio-temporal three-dimensional image creation unit, which creates a three-dimensional image from the time-series images continuously acquired by the continuous image acquisition unit 5 with the depth in the time direction. The section creation instruction UI unit 9 provides a user interface (UI) for designating a section to be displayed in the three-dimensional image created by the spatiotemporal three-dimensional image creation unit 8. Reference numeral 10 denotes a section creation unit, which is an arbitrary section including the time direction (depth direction) of the spatiotemporal three-dimensional image generated by the spatiotemporal three-dimensional image creation unit 8 (this section is designated by the section creation instruction UI unit 9). Be created). Reference numeral 11 denotes a cross section display unit, which displays a cross section generated by the cross section creation unit 10 on a display. The display used by the moving image display unit 6 and the cross section display unit 11 for display may be common.
[0014]
The respiratory dynamic images obtained by the present system are a plurality of human chest X-ray images. Hereinafter, in the embodiment, each of a plurality of images constituting such a dynamic image is referred to as a frame image. In FIG. 2, assuming that five frame images exist, the frame images obtained at the respective timings T1 to T5 are shown side by side. Displaying the frame images of the moving image side by side as shown in FIG. 2 is effective when closely examining each frame image. However, it is generally unsuitable for diagnosis because many frame images must be arranged. Therefore, normally, frame images are continuously switched and displayed on a screen of a frame size and observed as a moving image. Obviously, the method of observing as a moving image is advantageous for intuitively grasping the dynamics of the observer, but it takes time to observe a moving image. In the case of a moving image, it is difficult to leave an objective diagnosis record. That is, although a moving image has a lot of information, it must be dynamically displayed and observed, and it is difficult to leave an objective diagnosis record in a document or the like. On the other hand, if a still image is used, anyone can observe the image at any time, and marking is easy, so that an objective record can be recorded.
[0015]
Therefore, in the present embodiment, in order to objectively show the dynamic state, for example, the pixel value of each frame image on the horizontal line in FIG. The frame images to be taken out are rearranged in chronological order to form one image as shown in FIG. In FIG. 3, images are formed by rearranging them from the bottom in the order of T1, T2,..., T5. According to such an image shown in FIG. 3, the temporal movement / fluctuation of the shadow indicated by S1 in FIG. 2 is obtained as one image.
[0016]
According to the image as described above, for example, assuming that S1 in FIG. 2 is a tumor shadow, an anatomical judgment can be easily made as to whether or not S1 is adhered to the chest wall on the left side (FIG. 2, FIG. In the example of No. 3, it can be seen that there is no adhesion to the left chest wall). Such a determination is usually difficult to determine from a single still image due to various factors such as the shooting direction and timing. As shown in the image of FIG. 3, it is medically important to be able to confirm that there is no adhesion by imaging at a certain timing, and the contribution of the image display as shown in FIG. 3 to diagnosis is high. Further, if such a single image is formed, a record of the state of diagnosis can be easily left.
[0017]
Similarly, the pixel sequence of each frame image on the vertical line shown in FIG. 2B is rearranged in chronological order, is represented in one image as shown in FIG. It can be confirmed that S2 is not one shadow but two shadows separated from each other. In FIG. 4, the pixel rows obtained from each frame image are arranged in order from T1 to T5 from left to right.
[0018]
The images shown in FIGS. 3 and 4 described above are referred to as “spatio-temporal three-dimensional images (detailed in FIGS. 5 and 6)” in which a plurality of time-series continuous images are taken in depth in the time direction. It corresponds to a horizontal cross-sectional image and a vertical cross-sectional image of a three-dimensional image obtained by handling. Hereinafter, images as shown in FIGS. 3 and 4 are referred to as time-series cross-sectional images.
[0019]
Normally, the above-described diagnosis of adhesion or the like is obtained only from three-dimensional information of the human body by CT scan or the like. However, by observing a time-series cross-sectional image as in the present method, the diagnosis is equivalent. Such a diagnosis is also possible.
[0020]
In the above description, five frame images are shown for convenience of illustration and description. However, it is assumed that a moving image having at least 30 frames or more is used instead of such a small number of frames. Further, when arranging one pixel row on the designated line, one or more interpolation pixel rows may be inserted between the pixel rows to form a time-series cross-sectional image as shown in FIG. 3 or FIG. Good. Alternatively, a plurality of pixel columns including a pixel column on a line may be extracted from each frame, and the time-series cross-sectional images as shown in FIGS. 3 and 4 may be arranged and generated using the extracted columns.
[0021]
In the section creation instruction UI unit 9, for example, as shown in FIG. 2, a plurality of frame images are displayed side by side, the position of the line A is moved by an instruction from a pointing device or a keyboard, and a desired section position is designated. What should I do? When the line B is designated, a display indicating the line B may be performed on each frame image as shown in FIG. In this case, for example, when the line B in one frame image (for example, the line B of T1) is moved, the line B in another frame image is also moved by the same amount. Alternatively, when the line B is designated, the frame images may be displayed side by side in the vertical direction and the line B may be set. In such a UI, since the spatio-temporal three-dimensional image created by the spatio-temporal three-dimensional image creating unit 8 does not need to be used, the spatio-temporal three-dimensional image creating unit 8 can be omitted.
[0022]
Although it is possible to configure a UI for specifying a cross section as described above, in the present embodiment, a UI that allows a doctor or a device operator to easily form such a cross section while observing an image. Suggest. In this UI, the three-dimensional image created by the spatio-temporal three-dimensional image creation unit 8 is displayed, and a desired section is designated by the user.
[0023]
FIG. 5 shows a spatio-temporal three-dimensional image created by the spatio-temporal three-dimensional image creating unit 8. In addition to the X and Y directions of a normal two-dimensional image, the T direction, which is a time axis, is added to the depth. It constitutes a three-dimensional space. Therefore, one point in the space shown in FIG. 5 can be represented by three values of (x, y, T). As a method of displaying a three-dimensional image, there are a method of expressing a translucent object by ray tracing, and a method of obscuring a rear image with a front image.
[0024]
In the section creation instruction UI unit 9 of FIG. 1, a three-dimensional image as shown in FIG. 5 is displayed, and the user gives a section instruction in order to obtain his desired section image while watching this display. For example, T = C as a section equation; C is a constant (Equation 1)
If the plane is selected and C is made variable, normal frame images can be observed.
[0025]
In addition, Y = A as a sectional equation; A is a constant (Equation 2)
Is selected, a cross-sectional image of a plane parallel to the XT plane as shown in FIG. 6A is obtained. That is, a cross-sectional image as shown in FIG. 3 is obtained, and observation, diagnosis, and recording become possible.
[0026]
X = B as a sectional equation; B is a constant (Equation 3)
6B, a sectional image of a plane parallel to the YT plane can be obtained. That is, a cross-sectional image as described with reference to FIG. 4 is obtained, and observation, diagnosis, and recording can be performed.
[0027]
Generally, the user can select any plane, and that plane is a general equation such as:
T = Kx.X + Ky.Y + K1; Kx, Ky and K1 are constants (Equation 4)
Or two equations that are equivalent but can be expressed in different expressions:
X = Ky · Y + Kt · T + K2; Ky, Kt, and K2 are constants (Equation 5)
Y = Kx.X + Kt.T + K3; Kx, Kt and K3 are constants (Equation 6)
Is represented by
[0028]
While observing the three-dimensional image, the operator can select a desired cross section by moving the plane (for example, planes A and B in FIG. 6) displayed on the screen in parallel and rotationally by operating the mouse, for example.
[0029]
FIG. 7 is a flowchart illustrating a generation process of a time-series cross-sectional image in the respiratory dynamic imaging device of the present embodiment.
[0030]
First, in step S11, the spatiotemporal three-dimensional image creation unit 8 generates a spatiotemporal three-dimensional image as shown in FIG. 5 using a plurality of temporally continuous X-ray image groups stored in the storage device 7. . The section creation instruction UI unit 9 displays this on a display (not shown). In generating a spatiotemporal three-dimensional image, an interpolated frame image may be generated and inserted between each frame image.
[0031]
In step S12, the user sets a cutout plane so as to specify a desired cross section of the three-dimensional image while referring to the three-dimensional display. As the cutout plane, in addition to the planes A and B shown in FIG. 6, it is also possible to set planes inclined with respect to the X, Y, and T axes as shown in FIG. Operations such as movement and rotation of the cutout plane are performed by a mouse, but such a three-dimensional image and plane display processing will be apparent to those skilled in the art.
[0032]
By setting the cutout plane in step S12, each constant in any of equations 4 to 6 is determined, and the process proceeds to step S13. In step S13, an intersection line between the frame image and the plane for clipping is acquired from each frame image, and a pixel row along the intersection line is acquired. This is shown in FIG. In FIG. 9, L1, L2, L3, and L4 are shown as intersections between the cutout plane 91 and each of the frame images (T1 to T4). Note that these intersection lines can be obtained by using the expression of the plane for cutting determined in step S12.
[0033]
Subsequently, in step S14, the pixel sequence obtained in step S13 is arranged according to the time-series order of the cut-out frame image to generate a time-series cross-sectional image (92 in FIG. 9). Note that the arrangement of the pixel columns may be such that the user can set, for example, in order of time sequence from bottom to top, top to bottom, left to right, right to left, and the like. As described above, in generating a time-series cross-sectional image, an interpolated pixel row may be generated and inserted between the acquired pixel rows.
[0034]
The time-series cross-sectional image 92 generated as described above is displayed on the display by the cross-section display unit 11.
[0035]
[Second embodiment]
The method of expressing the cross section is not limited to the embodiment of FIGS. 3 and 4 shown in the first embodiment. For example, a form as shown in FIG. 10 can be used. FIG. 10 is a diagram illustrating a method for displaying a time-series cross-sectional image according to the second embodiment when 103 is specified as the time-series cross section. The partial image 101 above the specified cross section of the frame T1 and the partial image 102 below the specified cross section of the frame TN are displayed separately, and the cross sectional image 103 is connected so as to connect the partial images 101 and 102. Arrange and display.
[0036]
FIG. 11A shows an image of a cross section corresponding to FIG. 3 in accordance with the method shown in FIG. FIG. 11B shows a longitudinal section corresponding to FIG. 4 in accordance with the method shown in FIG. With such a three-dimensional display, the observer can observe while observing more clearly which cross-section is actually being changed over time, and by recording this image, it becomes more objective. Diagnostic records can be stored.
[0037]
An object of the present invention is to provide a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and a computer (or CPU or MPU) of the system or apparatus to store the storage medium. It is needless to say that the present invention can also be achieved by reading and executing the program code stored in the program.
[0038]
In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the program code and the storage medium storing the program code constitute the present invention.
[0039]
As a storage medium for supplying the program code, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, and the like can be used.
[0040]
When the computer executes the readout program code, not only the functions of the above-described embodiments are realized, but also an OS (Operating System) running on the computer based on the instruction of the program code. It goes without saying that a case where some or all of the actual processing is performed and the functions of the above-described embodiments are realized by the processing is also included in the embodiment of the present invention.
[0041]
Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. It is needless to say that a case where the CPU of the board or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing is also included in the embodiment of the present invention.
[0042]
【The invention's effect】
As described above, according to the present invention, an image effective for diagnosis can be generated based on a dynamic image.
[Brief description of the drawings]
FIG. 1 is a block diagram of a first embodiment of the present invention.
FIG. 2 is a diagram schematically illustrating each frame of a dynamic chest image.
FIG. 3 is a diagram in which a time variation of a specific horizontal line is imaged.
FIG. 4 is a diagram in which a time variation of a specific vertical line is imaged.
FIG. 5 is a schematic diagram of a spatiotemporal three-dimensional image.
FIG. 6 is a diagram showing a planar cross section of a spatiotemporal three-dimensional image.
FIG. 7 is a flowchart illustrating a generation process of a time-series cross-sectional image in the respiratory dynamic imaging device of the present embodiment.
FIG. 8 is a diagram illustrating setting of a cross section of a spatiotemporal three-dimensional image using a plane for cutting out.
FIG. 9 is a diagram illustrating a state in which a pixel sequence on a time-series cross section is acquired from each frame and a time-series cross-sectional image is generated.
FIG. 10 is a diagram illustrating a display mode of a time-series cross-sectional image according to a second embodiment.
FIG. 11 is a diagram illustrating a display example of a time-series cross-sectional image according to the second embodiment.

Claims (17)

Acquisition means for acquiring, from each of the plurality of images constituting the dynamic image of the target object, a pixel array arranged along a set straight line,
An image processing apparatus comprising: a generation unit configured to generate an image based on a plurality of pixel columns acquired from the plurality of images by the acquisition unit. The image processing apparatus according to claim 1, wherein the generation unit arranges the plurality of pixel columns based on a time-series order of an acquisition source image. The acquisition unit is configured to acquire a pixel row arranged along a line of intersection between a plane set in a spatiotemporal three-dimensional space in which the plurality of images are arranged along a time axis and each of the plurality of images. The image processing device according to claim 1. The image processing apparatus according to claim 3, further comprising a setting unit configured to set the plane based on an input by an operator. 2. The display device according to claim 1, further comprising a display unit configured to display the image generated by the generation unit together with a partial image cut out based on the straight line from a predetermined image of the plurality of images. Image processing device. The image processing apparatus according to claim 4, wherein the setting unit includes a display unit that provides a two-dimensional representation of the dynamic image and the plane in the spatiotemporal three-dimensional space. The image processing apparatus according to claim 1, wherein the dynamic image is generated based on an intensity distribution of radiation transmitted through the object. A system comprising: the image processing device according to claim 1; and a photographing device that photographs a dynamic state of an object. From each of the plurality of images constituting the dynamic image of the object, an acquisition step of acquiring a pixel row aligned along a set straight line,
A generating step of generating an image based on a plurality of pixel columns obtained from the plurality of images in the obtaining step. The image processing method according to claim 9, wherein in the generation step, the plurality of pixel columns are arranged based on a time-series order of an acquisition source image. In the acquiring step, a pixel row arranged along a line of intersection between a plane set in a spatio-temporal three-dimensional space in which the plurality of images are arranged along a time axis and each of the plurality of images is acquired. The image processing method according to claim 9, wherein: The image processing method according to claim 11, further comprising a setting step of setting the plane based on an input by an operator. The image according to claim 9, further comprising a display step of displaying the image generated in the generation step together with a partial image cut out from a predetermined image of the plurality of images based on the straight line. Processing method. The image processing method according to claim 12, wherein the setting step includes a display step of giving the two-dimensional representation of the dynamic image and the plane in the three-dimensional space-time space. 15. The image processing method according to claim 9, wherein the dynamic image is generated based on an intensity distribution of radiation transmitted through the object. A program for causing a computer to execute the method according to claim 9. A computer-readable storage medium storing the program according to claim 16.

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