JP3667372B2 - Medical image processing device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a medical image processing apparatus that can be used as both an X-ray CT apparatus and a nuclear medicine diagnostic apparatus.
[0002]
[Prior art]
The X-ray CT apparatus is an apparatus for obtaining a tomographic image of a subject by exposing X-rays from many directions, and FIG. 6 shows a typical configuration thereof.
As shown in the figure, the gantry 200 includes an X-ray tube 210 for irradiating the subject 101 with X-rays, and X-rays detected by a number of sensors arranged on the plane of the X-rays transmitted through the subject 101. A collimator / wedge filter 215 for aligning the X-ray direction as emitted from the detector 220 and the point light source is arranged, and these are rotated about the subject 101 as an axis. A device 230 called a data acquisition device (DAS) is connected to the output of the X-ray detector 220, and a computer device 240 is connected to the DAS 230.
[0003]
The tomographic image is taken as follows. First, the X-ray tube 210, the collimator / wedge filter 215, and the X-ray detector 220 are rotated while shifting their positions little by little. The X-ray tube 210 irradiates the subject 101 with X-rays and detects the transmitted X-rays. Detect with detector 220. Then, the data collection device 230 converts the detection signals of the respective sensors of the X-ray detector 220 into digital values, and the computer device 240 collects this data. In the computer apparatus 240, an X-ray CT image is displayed on the monitor 250 by performing operations such as preprocessing, convolution, and back projection.
[0004]
A nuclear medicine diagnostic apparatus is an apparatus for detecting an image in a subject from γ rays emitted by making the subject drink a radioisotope, and FIG. 7 shows a typical configuration thereof.
[0005]
As shown in the figure, a detector 320 for detecting γ rays with the subject 101 as a focal point is arranged in the gantry 200, and this detector 320 has a large number of scintillators and rotates around the subject 101 as an axis. It is supposed to be. An interface device 330 for connecting to the computer device 240 is connected to the output of the detector 320, and this device 330 analyzes the pulse height of the output of the detector 320 and performs A / D conversion to provide it to the computer device 340. It has become. The computer device 340 reconstructs an image from the digitized output of the detector 320 and displays a tomographic image of γ rays on the monitor 350.
[0006]
Data collection by this apparatus is performed by shifting the position of the detector 320 little by little and rotating the focus of the detector 320 around the axis. Γ-rays are detected from the wave height of the output of the detector 320, A / D converted and collected by the computer device 340, and image reconstruction is performed.
[0007]
[Problems to be solved by the invention]
Since the X-ray CT apparatus and the nuclear medicine diagnosis apparatus are separate modalities using radiation, when performing both diagnosis by X-ray CT image and nuclear medicine diagnosis, each apparatus is required and each protects radiation. In order to need a shielded room. And when trying to obtain an image of the same part of the same subject, images taken by different apparatuses are used, and the same image cannot be obtained. Even when trying to obtain the same one as much as possible, alignment is difficult, and it is difficult to obtain an image that can be superimposed.
Accordingly, an object of the present invention is to provide a medical image processing apparatus that can be used as both an X-ray CT apparatus and a nuclear medicine diagnostic apparatus.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a medical image processing apparatus according to claim 1 of the present application collects data by detecting radiation by rotating a radiation detector around a subject, and reconstructs an image from the data. A medical image processing apparatus for constructing an image inside the subject by an X-ray source for exposing the subject to X-rays, and facing the X-ray source so as to sandwich the subject and a two-dimensional radiation detector which is an input means for setting the X-ray CT mode and nuclear medicine diagnostic mode, a collimator that limits the direction of the radiation incident on the two-dimensional radiation detector, said input means An X-ray image reconstruction algorithm for constructing an X-ray CT image from data obtained by detecting the X-ray from the X-ray source with the two-dimensional radiation detector based on the mode set by Gamma rays from the two-dimensional And a reconstruction means for reconstructing switching between γ-ray image reconstruction algorithm which constitutes the γ-ray image from the data obtained by detecting by ray detector.
[0011]
[Action]
According to the medical image processing apparatus of the present invention, since both X-ray CT and γ-ray image data can be reconstructed, it is used as an X-ray CT apparatus and a nuclear medicine diagnostic apparatus. Can
[0014]
【Example】
Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a system configuration of a medical image processing apparatus according to an embodiment of the present invention.
[0015]
In the central part of the gantry 400, a hole for inserting the subject 101 is provided, and an X-ray tube 410, a detector 420, and a collimator 470 are arranged with the subject 101 interposed therebetween, and these are provided for the subject 101. It is designed to rotate around the center.
[0016]
The X-ray tube 410 is an X-ray source for exposing X-rays to the subject 101, and performs exposure in accordance with control from the controller 460. The detector 420 is for two-dimensionally detecting X-rays and radiation that have passed through the subject 101, and includes a number of sensors arranged in a matrix.
[0017]
FIG. 2 shows a configuration example of the detector 420. The collimator 421 is provided with a large number of holes in a matrix in the vertical direction of the figure, the scintillator 422 is provided corresponding to the holes, and the semiconductor sensor. 423 is arranged so as to overlap. The collimator 421 is for preventing the incidence of radiation from the lateral direction, and guides the radiation from above in the figure to the scintillator 422. The scintillator 422 emits fluorescence when radiation is incident, and crystals such as NaI and CsI are used. The semiconductor sensor 423 is for detecting the light emission of the scintillator 422 in two dimensions, and is configured by a two-dimensional arrangement of photodiodes for each pixel, a CCD sensor having a large light receiving surface, or the like. For the X-ray, the detector 420 outputs a signal corresponding to the intensity of each pixel, and for the γ-ray, the light emitted from the scintillator 422 is accumulated and a signal corresponding to the integrated value is output as the γ-ray intensity. In the case of a photodiode, it is also possible to detect γ-rays from the peak value and integrate them with the data processing unit 430 to convert them into γ-ray intensity.
[0018]
The detector 420 has a variable focus by restricting the direction of incident radiation by the collimator 470. FIG. 3 shows a configuration example of the collimator 470. Assuming that the direction on the X-ray tube 410 side is the z direction, the collimator 470 includes a number of collimator blades 474 arranged in parallel to the x direction and a number of collimator blades 472 arranged in parallel to the y direction perpendicular thereto. These collimator blades are configured to change the angle by motors 478 and 476.
[0019]
FIG. 4 shows this state, and the angle at which the collimator blade is in the direction about the X-ray tube 410 as shown in (a), and the direction around the subject 101 as shown in (b). The collimator blade is tilted at an angle of. When tilted as in (a), the detector 420 detects only radiation in the direction centered on the X-ray tube 410, and the focus of the detector 420 is the X-ray tube 410. When tilted as in (b), the detector 420 detects only radiation in the direction centered on the subject 101, and the focus of the detector 420 is near the center of the subject 101. Servo motors or step motors are used as the motors 478 and 476, and the tilt angle of the collimator blade is accurately controlled by the controller.
[0020]
A data acquisition unit 430 is connected to the output of the detector 420. The data acquisition unit 430 converts the output of the detector 420 into a digital value by A / D conversion, and collects this radiation image data to obtain an image reconstruction unit. To 440.
[0021]
The image reconstruction unit 440 is configured using a computer system, and is a device for reconstructing an image from the radiation image data detected and collected by the detector 420, and the monitor 450 is a device for displaying the image. It is. As shown in FIG. 5, the image reconstruction unit 440 includes an X-ray image reconstruction algorithm and a γ-ray image reconstruction algorithm as image reconstruction algorithms. This algorithm is equivalent to the above-described conventional example, and the switching is performed in accordance with either the X-ray CT mode or the nuclear medicine diagnosis mode. The selection of the operation mode is transmitted to the controller 460.
[0022]
The controller 460 controls the rotation angle of the motors 478 and 476 so as to set the angle of the collimator blade according to the operation mode, and exposes the X-rays to the subject 101 in the X-ray CT mode. The X-ray tube 410 is controlled. The controller 460 is also configured using a computer system.
Next, the operation of the medical image processing apparatus of FIG. 1 will be described together with the algorithm of FIG.
[0023]
First, one of the operation modes of the X-ray CT mode and the nuclear medicine diagnosis mode is selected and input from the console (reference numeral 440a in FIG. 5). Next, the operation mode is transmitted from the image reconstruction unit 440 to the controller 460, and the angle of the collimator blade is set by the controller 460 (reference numeral 440b in FIG. 5). The angle of the collimator blade is controlled so that the X-ray tube 410 is the focal point of the detector 420 as shown in FIG. 4A in the X-ray CT mode, and as shown in FIG. 4B in the nuclear medicine diagnosis mode. The subject 101 is controlled to be the focal point of the detector 420. Then, the process branches to an algorithm corresponding to the operation mode (reference numeral 460c in FIG. 5).
[0024]
In the X-ray CT mode, the controller 460 emits X-rays from the X-ray tube 410 to the subject 101, and the X-ray tube 410, the detector 420, and the collimator 470 are shifted little by little with respect to the subject 101 as an axis. Rotate. Each time the position is changed, the intensity of the transmitted X-ray image is detected for each pixel by the detector 420, converted into a digital value by the data acquisition unit 430, and data is collected (reference numeral 462d in FIG. 5). The collected X-ray image data is processed by an X-ray image reconstruction algorithm in the image reconstruction unit 440 to form an X-ray CT image showing the inside of the subject 101 (reference numeral 462e in FIG. 5). The X-ray CT image is displayed on the monitor 450 (reference numeral 462f in FIG. 5).
[0025]
In the nuclear medicine diagnosis mode, X-ray exposure from the X-ray tube 410 is not performed, and the X-ray tube 410, the detector 420, and the collimator 470 rotate while shifting their positions little by little about the subject 101 as an axis. Every time the position is changed, the intensity of the γ-ray from the subject 101 is detected by the detector 420 for each pixel, converted into a digital value by the data acquisition unit 430, and data is collected (reference numeral 464d in FIG. 5). The collected γ-ray image data is processed by a γ-ray image reconstruction algorithm in the image reconstruction unit 440 to form a γ-ray image showing the inside of the subject 101 (reference numeral 464e in FIG. 5). This γ-ray image is displayed on the monitor 450 (reference numeral 460f in FIG. 5).
[0026]
In this manner, since the focus of the detector 420 is changed by the collimator 470, the X-ray CT image data and the image data for nuclear medicine diagnosis can be collected. This medical image processing apparatus can be used as both an X-ray CT apparatus and a nuclear medicine diagnostic apparatus. Since image data is collected for the same subject 101 using the same apparatus, an X-ray CT image and a γ-ray image can be obtained for the same part and the same position. Since these can be superimposed, it becomes easy to diagnose.
[0027]
Further, the image reconstruction unit 440 has an X-ray image reconstruction algorithm and a γ-ray image reconstruction algorithm, and the apparatus configuration is simplified and compact because it is switched according to the operation mode. .
[0028]
Conventionally, a shield room is required for each of the X-ray CT apparatus and the nuclear medicine diagnosis apparatus, and the facilities have become enormous. However, in the present invention, these can be integrated into one, so that the apparatus can be made compact. Also, the inspection time can be shortened.
[0029]
【The invention's effect】
As described above , according to the present invention, an X-ray CT image and a γ-ray image can be obtained by switching between an X-ray image reconstruction algorithm and a γ-ray image reconstruction algorithm. Units can be combined into a compact one.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of a medical image processing apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram showing a configuration example of a detector.
FIG. 3 is a diagram showing a configuration example of a collimator.
FIG. 4 is a diagram showing the inclination of a collimator.
FIG. 5 is a diagram showing an image reconstruction algorithm.
FIG. 6 is a diagram showing a typical X-ray CT apparatus.
FIG. 7 is a diagram showing a typical nuclear medicine diagnostic apparatus.
[Explanation of symbols]
410 X-ray tube, 420 Two-dimensional radiation detector, 470 Collimator 440 Image reconstruction unit 462e X-ray image reconstruction algorithm 464e γ-ray image reconstruction algorithm 472, 474 Collimator blade 476, 478 Motor

Claims (3)

A medical image processing apparatus that collects data by detecting radiation by rotating a radiation detector around a subject, and constructs an image inside the subject by image reconstruction from the data,
An X-ray source for exposing the subject to X-rays;
A two-dimensional radiation detector provided facing the X-ray source so as to sandwich the subject;
Input means for setting the X-ray CT mode and the nuclear medicine diagnosis mode;
A collimator that limits the direction of the radiation incident on the two-dimensional radiation detector,
An X-ray image reconstruction algorithm for constructing an X-ray CT image from data obtained by detecting the X-ray from the X-ray source by the two-dimensional radiation detector based on the mode set by the input means; Reconstructing means for switching and reconstructing a γ-ray image reconstruction algorithm for constructing a γ-ray image from data obtained by detecting γ-rays from the subject with the two-dimensional radiation detector. A medical image processing apparatus. The medical image processing apparatus according to claim 1, wherein the collimator changes a focus based on a mode set by the input unit. The collimator includes a plurality of first collimator blades arranged on the subject-side surface of the two-dimensional radiation detector, and a plurality of second collimator blades arranged in a direction perpendicular to the first collimator blade. And a first motor for changing the inclination of the first collimator blade, and a second motor for changing the inclination of the second collimator blade. Item 2. The medical image processing apparatus according to Item 1.

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