JP2000102529A - Radiation imaging instrument and storage medium readable by computer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a structure for preventing the lowering of a frame rate and prevent the displacement between the frontal and lateral images in a biplane radiation imaging instrument. SOLUTION: Alternate irradiation images as the transmission images of an object 1 are obtained from the radiation detector 12 and 22 by alternately operating the radiation sources 11 and 21, and stored in the storage parts 17 and 27, and the images formed by scattering lines diffused from the object 1 are stored in the storage parts 16 and 26. Then the switches are turned to simultaneously operate the radiation sources 11 and 21, the movement of the object 1 is detected by the movement detecting parts 18 and 28 on the basis of the obtained images and the images from the storage parts 17 and 27, and the obtained image is corrected on the basis of the scattering line images of the storage parts 16 and 26 by the subtracters 19 and 29 when the movement is not detected. When the movement is detected, the alternate irradiation is executed again, and the storage parts 16 and 26 are updated by the obtained scattering line images.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of irradiating a subject with radiation and transmitting a radiation intensity distribution through the subject,
A radiation imaging apparatus for acquiring a radiation image and a computer-readable storage medium used in the radiation imaging apparatus,
In particular, it is suitable for use in a biplane radiation imaging apparatus that images a subject from a plurality of directions.

[0002]

2. Description of the Related Art A radiation imaging apparatus which irradiates a subject with radiation and detects the intensity distribution of the transmitted radiation to obtain an image of the internal structure of the subject as an image has conventionally been used for industrial nondestructive inspection, medical diagnosis and the like. Widely used in The most common imaging method for obtaining a radiation image of a subject uses a combination of a fluorescent plate (or intensifying screen) that emits fluorescence by radiation and a silver halide film,
A method of irradiating a subject with radiation and converting the transmitted radiation into visible light with a fluorescent plate to expose a silver halide film and chemically treating the silver halide film to obtain a visible image is often used.

The above-mentioned method is a method for obtaining a still image, but a method for obtaining a moving image is as follows. In the past, the method started by directly observing the light emission of a fluorescent plate, and was followed by a photomultiplier tube or an image intensifier (hereinafter, I .I.), The output light is amplified, and then recorded on a cine film. In recent years, a method of digitizing and recording a radiation image by using a photoelectric conversion device such as a CCD for a recording unit has been used.

In contrast, in IVR such as contrast imaging performed by inserting a catheter and injecting a contrast agent, or treatment of stenosis of a blood vessel by inserting a balloon, it is necessary to obtain a spatial structure of a blood vessel. On the other hand, so-called biplane imaging or the like, in which radiation is irradiated from two directions to detect transmitted radiation, respectively, is performed.

[0005]

The radiation passing through the subject is attenuated by absorption and scattering. These absorption and scattering are affected by the properties of the object such as the density, effective atomic number, and thickness, and the wavelength of radiation. Of these, the attenuation due to the absorption of the object forms the object contrast, which causes the main information to be carried out. On the other hand, scattered radiation is radiation that is scattered without directivity, and reduces sharpness and contrast in the process of forming a radiation image. As a measure against this, I.I. I. A method is used in which a grid made of a thin metal foil grid is provided on the radiation incidence surface, and radiation effective for forming an image is transmitted, and scattered radiation is absorbed by the grid.

In the above-mentioned biplane imaging,
Since the radiation is irradiated from two directions (frontal and lateral), the method using the grid alone is not sufficient. As described above, the scattered radiation has no directionality and is generated in every part of the subject. For this reason, if the radiation is irradiated in the frontal system, the scattered radiation component of the radiation that diffuses in the same direction as the lateral system is not absorbed by the grid, but is incident on the image receiving portion of the lateral system. Degrades the image.

As a countermeasure against this, conventionally, irradiation of frontal radiation and lateral radiation is alternately performed, and an electric or mechanical shutter is provided in the image receiving unit to perform blanking, thereby reducing the influence of scattered radiation in the mutual system. The method of avoiding is used.

However, in the above method, radiation irradiation (imaging) and blanking are performed alternately, so that the frame rate is reduced by half, and the timing of radiation irradiation is different between frontal and lateral, so that a time lag occurs between images. In addition, there are problems such as that the mechanisms of the image receiving unit and the radiation control unit are complicated to perform blanking.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem. In bi-plane imaging, by eliminating a blanking operation, the timings of irradiation of frontal radiation and lateral radiation can be performed substantially simultaneously. Accordingly, it is intended to substantially eliminate a time lag between the two images.

[0010]

In order to achieve the above object, in a radiation imaging apparatus according to the present invention, first irradiating means for irradiating a subject with radiation from a first direction;
First detection means for detecting radiation transmitted through the subject from the first direction and outputting image data, and second irradiation means for irradiating the subject with radiation from a second direction;
Second detection means for detecting radiation transmitted through the subject from the second direction and outputting image data, and scattering obtained from the second detection means when only the first irradiation means is operated. Storage means for storing first scattered-ray image data by X-rays; and second scattered-ray image data by scattered radiation obtained from the first detection means when only the second irradiation means is operated. When the storage means and the first and second irradiation means are operated simultaneously, the image data obtained from the first detection means is corrected with the stored second scattered radiation image data, and And a correcting means for correcting the image data obtained from the second detecting means with the stored first scattered radiation image data.

In a computer readable storage medium according to the present invention, an irradiation process of irradiating a subject with radiation from a first direction using a first irradiating means; A detection process of detecting the radiation transmitted through the first detection unit and outputting image data, irradiating the subject with radiation from a second direction by using a second irradiation unit, A detection process of detecting the radiation transmitted through the subject from the second direction using the second detection means and outputting image data; and detecting the radiation from the second detection means when only the first irradiation means is operated. A storage process for storing first scattered-ray image data obtained by scattered radiation, and a second scattered-ray image by scattered radiation obtained from the first detection unit when only the second irradiation unit is operated. data When the storage process for storing and the first and second irradiation units are simultaneously operated, the image data obtained from the first detection unit is corrected with the stored second scattered radiation image data, A program for executing a correction process of correcting the image data obtained from the second detection means with the stored first scattered-ray image data is stored.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing a first embodiment of the radiation imaging apparatus according to the present invention. In FIG.
For the subject 1, a frontal radiation source 11 and a radiation detector 12 are provided, and a lateral radiation source 21 and a radiation detector 22 are provided. The radiation detectors 12 and 22 convert incident radiation transmission images into electric signals. I. And a two-dimensional photoelectric conversion element made of CCD or amorphous silicon or amorphous selenium, on which a phosphor is laminated, or the like. Each of these outputs an analog electric signal corresponding to the amount of radiation incident on each pixel for each pixel.

[0013] Figure 2 shows the operation timing, X _F
The irradiation timing, X _L of the frontal system showing the emission timing of the lateral system.

When the operator presses an imaging button (not shown), a scattered radiation image acquisition procedure is first performed. This procedure involves irradiating radiation alternately between frontal and lateral,
A scattered radiation image due to scattered radiation incident from different systems,
An uncorrected image obtained by alternate irradiation is obtained.

First, irradiation is performed from the frontal side. At this time, the system controller 30
4, 15, and 24 are connected to the a side. Next, the system controller 30 operates the radiation source 11 according to the separately set tube current, tube voltage, and irradiation time to emit radiation. The radiation passes through the subject 1, and the transmitted image is converted into an analog electric signal by the radiation detector 12. This analog electric signal is converted by the A / D converter 13 into digital image data _IF0 of FIG. This _IF0 is switch 1
4 and 15 are stored in the storage unit 17 as the non-corrected alternate irradiation image.

In the above-described imaging, scattered radiation generated due to the radiation from the radiation source 11 on the frontal side being scattered by the subject 1 is incident on the radiation detector 22 on the lateral side. The analog electric signal output from the radiation detector 22 is converted into digital image data S _L0 by the A / D converter 23. This S _L0 is stored in the storage unit 2 via the switch 24.
6 is stored as a scattered radiation image.

Next, in order to perform irradiation from the lateral side, the system controller 30 connects the switches 24, 25 and 14 to the side b. And the radiation source 21
Irradiates the image data I in the storage unit 27.
_L0 is stored as an alternating irradiation uncorrected image, and the image data S _F0 is stored in the storage unit 16 as a scattered radiation image. As described above, the scattered radiation images S _F0 and S _L0 and the unirradiated non-corrected images I _F0 and I _L0 are obtained in the frontal and lateral systems, respectively.

In this case, the above-mentioned alternating irradiation uncorrected image I _F0 ,
I _L0 is an image acquired by irradiating the radiation alternately and independently, and thus does not affect the mutual system by scattered radiation. For this reason, the system controller 30 controls the later-described movement detection units 18 and 28 and the subtractors 19 and 29 to be described later so that the data passes through, and the alternate irradiation uncorrected image stored in the storage units 17 and 27. I _F0 and I _L0 are output.

Next, a frontal and lateral simultaneous irradiation procedure is performed. For this purpose, the system controller 30 connects the switch 14 to the side a and the switch 15 to the side b. The switch 24 is connected to the b side, and the switch 25 is connected to the a side.

In this state, the radiation sources 11 and 21
Irradiates the subject 1 and transmits or scatters it.
Radiation enters the radiation detectors 12 and 22, and the A / D
Simultaneous irradiation uncorrected image I of FIG.
_F1, I_L1Is obtained. This I _F1, I_L1Is the movement of subject 1.
Sent to motion detectors 18 and 28 to detect movement of subject 1
Is done.

In the movement detecting sections 18 and 28, the storage section 17 and
Internal configuration of the subject 1 such as a heart, a blood vessel, and other organs depicted in the alternate irradiation uncorrected images I _F0 and I _L0 stored in the memory 27 and the simultaneous irradiation uncorrected images I _F1 and I _L1 just acquired. The movement of the subject 1 is detected by extracting the element and detecting the movement vector of the area, perimeter, and center of gravity. Generally, the scattered radiation is caused by radiation scattered by the subject 1, and therefore is not significantly affected by a slight movement of the subject 1, for example, a body movement due to respiration.

However, the imaging part is continuously changed while moving the imaging table on which the subject 1 is placed.
Alternatively, when the imaging region of the subject 1 changes, or when the moving direction increases as the radiation incident direction changes, the distribution of the scattered radiation also changes greatly. For this reason, when the detected movement amount of the subject 1 exceeds a certain threshold value, a scattered radiation image acquisition procedure by alternate irradiation is performed again as described later. The simultaneous irradiation procedure is performed by judging that it is within the range.

Now, I_F1, I_L1Of the subject 1
If not issued, I_F1, I _L1Is the subtractor
19, 29, where the scattered radiation in the storage units 16, 26
Image S_F0, S_L0Is subtracted, and the corrected image is
Image data is output. After that, the movement of the subject 1 is detected
The above operation is performed until the operation is performed.

Next, the simultaneous irradiation uncorrected images I _F6 and I _{F6 of} FIG.
It is assumed that when _L6 is acquired, the movement of the subject 1 is detected by the movement detection units 18 and 28. At this time, I _F6 -S _F0 and I _L6 -S _L0 are output as the corrected images. After the output, the scattered radiation image acquisition procedure by the alternate irradiation described above is performed again, and the scattered radiation images in the storage units 16 and 26 are updated to S _F1 and S _L1 .

[0025] In FIG. 2, when being carried out alternately irradiated again, BL _F, although the image to be output to the BF _L is absent, and outputs the image of the previous frame as it is or, alternatively subtractor 19 and 29 An inter-frame interpolation means may be provided at the subsequent stage to create and output image data interpolated from the preceding and following data. Thereafter, while the imaging is being performed, the above operation is repeated each time a predetermined movement is detected by the movement detection units 18 and 28, and the scattered radiation images in the storage units 16 and 26 are updated.

Next, a second embodiment of the present invention will be described with reference to FIG. In the above-described first embodiment, the movement of the subject 1 is detected from the amount of change between the alternating irradiation uncorrected image and the simultaneous irradiation uncorrected image. However, in the present embodiment, as shown in FIG. , Each switch 14, 15, 24, 25
Are connected. According to the configuration of FIG. 3, an image obtained at the time of simultaneous irradiation is corrected by the subtractors 19 and 29 using the scattered radiation images of the storage units 16 and 26, and an image obtained by alternate irradiation of the storage units 17 and 27. Is sent to the movement detecting units 18 and 28, the movement can be detected.

As another movement detection method, for example,
The movement may be detected from a visible light image obtained from a video camera or the like without using the radiation image. In addition, a movement detecting unit such as an acceleration sensor or a capacitance detector that is in contact with or not in contact with a subject may be provided. Further, a movement detecting means such as an acceleration sensor or a potentiometer may be provided on the photographing table on which the subject is placed.

The system using the functional blocks shown in FIGS. 1 and 3 may be configured as hardware, or may be configured as a computer system including a CPU, a memory, and the like. When configured in a computer system, the memory constitutes a storage medium according to the present invention. The storage medium stores a program for executing the processing procedure for controlling the operation described above.

As the storage medium, ROM, R
Semiconductor memory such as AM, optical disk, magneto-optical disk,
A magnetic medium or the like may be used, and these may be configured and used in a CD-ROM, a floppy disk, a magnetic medium, a magnetic card, a nonvolatile memory card, or the like.

Therefore, this storage medium can be used in a system or apparatus other than the systems shown in FIGS. 1 and 3, and the system or computer can read out and execute the program code stored in this storage medium. In addition, the same functions as those of the above-described embodiments can be realized, the same effects can be obtained, and the object of the present invention can be achieved.

An OS running on a computer
Perform part or all of the processing, or after the program code read from the storage medium is written into the memory provided in the extended function board inserted into the computer or the extended function unit connected to the computer. ,
Even when the CPU or the like provided in the above-mentioned extended function board or extended function unit performs a part or all of the processing based on the instruction of the program code, the same functions as those of the embodiments can be realized and the same effects can be obtained. Can be obtained, and the object of the present invention can be achieved.

[0032]

As described above, according to the present invention,
When biplane imaging is performed, a scattered radiation image is obtained by alternate irradiation, and an image obtained by simultaneous irradiation is corrected by this scattered radiation image, thereby eliminating the blanking operation as in the past. , The frame rate can be prevented from lowering, the configuration of the image receiving unit and the radiation control unit can be simplified, and the timing of irradiation of the frontal and lateral radiations can be simultaneously eliminated to eliminate the time lag between the two images. Can be.

Further, the movement of the subject can be reliably detected, and the scattered radiation image is updated when the movement is detected, so that the image can be corrected with higher accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram of a radiation imaging apparatus according to a first embodiment of the present invention.

FIG. 2 is a timing chart showing an operation.

FIG. 3 is a block diagram of a main part of a radiation imaging apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Subject 11,21 Radiation source 12,22 Radiation detector 13,23 A / D converter 14,15,24,25 Switch 16,17,26,27 Storage unit 18,28 Movement detecting means 19,29 Subtractor 30 System controller

Claims (11)

[Claims] A first irradiating means for irradiating a subject with radiation from a first direction; a first detecting means for detecting radiation transmitted through the subject from the first direction and outputting image data; Second irradiating means for irradiating the subject with radiation from a second direction; second detecting means for detecting radiation transmitted through the subject from the second direction and outputting image data; Storage means for storing first scattered-ray image data based on scattered radiation obtained from the second detecting means when only the irradiating means is operated; and Storage means for storing second scattered radiation image data based on scattered radiation obtained from the first detection means, and when the first and second irradiation means are simultaneously operated,
The image data obtained from the first detecting means is corrected by the stored second scattered image data, and the image data obtained from the second detecting means is corrected by the stored first scattered image data. A radiation imaging apparatus comprising: a correction unit configured to perform correction. 2. The method according to claim 1, wherein when the first and second irradiation means are operated a plurality of times at the same time, a first and a second movement detecting the movement of the subject with respect to the first and second irradiation means each time. The radiation imaging apparatus according to claim 1, further comprising a movement detection unit. 3. A control in which, when one of the first and second movement detecting means detects the movement, irradiation of only the first irradiation means and irradiation of only the second irradiation means are sequentially performed. Means, and the first and second stored first and second scattered radiation image data obtained by the irradiation by the control means.
3. The radiation imaging apparatus according to claim 2, further comprising an updating unit for updating the second scattered radiation image data. 4. The first and second movement detecting means, each of which is obtained from the first and second detecting means by irradiation of only the first irradiation means and irradiation of only the second irradiation means. Detecting the movement from each change amount between the image data and each image data obtained from the first and second detection means by the simultaneous irradiation of the first and second irradiation means performed thereafter. The radiation imaging apparatus according to claim 2, wherein: 5. The image first and second movement detecting means include a visible light image acquiring means for acquiring a visible light image of the subject, and a first and a second movement detecting means of the image continuously outputted from the visible light image acquiring means. The radiation imaging apparatus according to claim 2, wherein the movement is detected from the amount of change. 6. The radiation imaging apparatus according to claim 2, wherein the image first and second movement detecting means are provided in contact with or not in contact with the subject, and directly detect the movement of the subject. 7. The radiation imaging apparatus according to claim 2, wherein the image first and second movement detecting means are provided on a table on which the subject is placed, and detect the movement of the table. 8. An irradiation process of irradiating a subject with radiation from a first direction using a first irradiating means, and applying radiation transmitted through the subject from the first direction to a first direction.
A detection process of detecting image data by using the detection means of (a) and outputting image data; an irradiation process of irradiating the subject with radiation from a second direction by using a second irradiation means; Transmit the transmitted radiation to the second
A detection process of detecting and outputting image data by using the detection means of (a), and a first scattered radiation image data by scattered radiation obtained from the second detection means when only the first irradiation means is operated. A storage process for storing; a storage process for storing second scattered-ray image data based on scattered radiation obtained from the first detection unit when only the second irradiation unit is operated; When the two irradiation means are operated at the same time,
The image data obtained from the first detection means is corrected by the stored second scattered image data, and the image data obtained from the second detection means is corrected by the stored first scattered image data. A computer-readable storage medium storing a program for executing a correction process for correcting. 9. A process for simultaneously operating the first and second irradiating means a plurality of times, and detecting a movement of the subject with respect to the first and second irradiating means for each of the first and second movement detection, respectively. 9. The computer-readable storage medium according to claim 8, further comprising a process of detecting using a means. 10. A control in which, when one of the first and second movement detecting means detects the movement, irradiation of only the first irradiation means and irradiation of only the second irradiation means are sequentially performed. Processing, and updating processing for updating the stored first and second scattered-ray image data with the first and second scattered-ray image data obtained by the irradiation by the control processing. The computer-readable storage medium according to claim 9, wherein: 11. The movement detecting process includes the steps of irradiating only the first irradiating means and irradiating only the second irradiating means with each image data obtained from the first and second detecting means, and thereafter, Wherein the movement is detected from the amount of change between each image data obtained from the first and second detection means by simultaneous irradiation of the first and second irradiation means. 10. The computer-readable storage medium according to claim 9.