JPH04221946A - Radiograph pickup system - Google Patents

Abstract

PURPOSE:To obtain a clear picture by preventing the influence of scattered X-rays from an object at the time of photographing of another case without necessitating carefulness in alignment, etc., at the time of photographing. CONSTITUTION:Stimulated luminous light radiated by irradiating a stimulable phosphor plate or sheet 5 which absorbs a part of radiation energy transmitted through the object 2 and accumulates it as a latent image with exciting light is converted to an electrical signal by a photoelectric converter and A/D converted to obtain image information. By reading the latent images obtained by photographing plural times by the use of the stimulable phosphor plate or sheet 5 larger than the object 2 and synthesizing the images based on area information specified by the size of a silver salt film and the area information of the plural respective radiographs picked up, the plural images are hard-copied on one silver salt film or displayed on one screen of a CRT 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiographic imaging system. More specifically, the present invention relates to a radiation image capturing system using a stimulable phosphor.

Radiographic images such as X-ray images are often used for disease diagnosis. In order to obtain this X-ray image, the X-rays that have passed through the subject are passed through a phosphor layer (fluorescent screen).
So-called radiography is used, in which a film using a silver salt is developed by irradiating it with visible light, which is then irradiated with the visible light.

On the other hand, as a high-sensitivity, high-resolution X-ray imaging system, instead of the conventional method of recording two-dimensional images of indirect or direct radiation on a film coated with a silver salt photosensitive agent in the form of a sheet, an accumulation Methods using photostimulable phosphors are beginning to be used.

[0004] Such a system is described in detail in US Pat. No. 3,859,527 as a basic system. When the phosphors used in this system receive energy from radiation such as X-rays, they store some of that energy.

[0005] This state is relatively stable and is maintained for a while or for a long time. When the phosphor in this state is irradiated with the first light that acts as excitation light, the stored energy is released as second light (stimulated luminescence light). At this time, the first light is not limited to visible light, but has a wide wavelength range from infrared to ultraviolet. However, the selection depends on the phosphor material used.

[0006] There are also various types of second light, ranging from infrared light to ultraviolet light. The difference also depends on the phosphor material used. This second electromagnetic wave is received, converted into an electrical signal by a photoelectric converter, and then converted into a digital signal to obtain digital image information.

[0007] In such a radiographic imaging method,
For example, when taking multiple images of a part of the human body as a subject and obtaining them as a single radiographic image, conventional methods take time to take the images or require images of the subject to be taken separately. Due to the influence of scattered X-rays from the subject at the time of imaging, there is a problem that the image becomes unclear compared to when the image is taken alone, and there is a need for a radiographic imaging method that can solve these problems. be done.

[0008]

2. Description of the Related Art FIGS. 3 and 4 are diagrams illustrating a radiation image capturing system using a stimulable phosphor. FIG. 3 shows a case where an imaging section and a reading section are separate, and FIG. 4 shows a case where an imaging section and a reading section are separate. This shows the case where the reading section and the reading section are integrated.

In FIGS. 3 and 4, 1 is an X-ray generator, 2 is an object, 3 is an irradiated X-ray, 4 is an imaging stand,
5 is a stimulable phosphor plate or sheet, 6 is a read-only machine, 7 is an insertion part of a stimulable phosphor plate or sheet, 8
9 is a reading section, 10 is an erasing section, 11 is a stimulable phosphor plate or sheet take-out section, 12, 14
1 is an image information transmission path, 13 is an image processing section, 15 is an image display section, and 16 is a supine position imaging device.

First, X-rays emitted from the X-ray generator 1 pass through the subject 2 and form a latent image on the photographing table 4 or on a stimulable phosphor plate or sheet 5 in the imaging device. The stimulable phosphor plate or sheet 5 is a photographing stand.
4, then the photostimulated phosphor plate of the read-only machine 6,
Alternatively, it is inserted into the insertion section 7 of the sheet. In that case, the stimulable phosphor plate or sheet 5 may be contained in a magazine or cassette (not shown).

Although FIG. 4 shows a case where the photographing section and the reading section are integrated, the basic operation is the same as when the photographing section and the reading section are separate. In either case of FIGS. 3 and 4, the stimulable phosphor plate or sheet 5 is automatically sent to the reading section 9, where the latent image is read. The read image information is subjected to image processing and then displayed on a CRT as a CRT image or hard-copied onto an X-ray film.

On the other hand, after the reading is completed, the stimulable phosphor plate or sheet 5 has its afterimage removed and is returned to the photographing section, or in the case of FIG. loaded.

Next, FIG. 5 shows an example of a schematic configuration of the reading section. In FIG. 5, 101 is an excitation light source (laser, etc.), 1
02 is a scanner such as a galvano mirror or a polygon mirror, 103 is an optical component for beam shape correction such as an fθ lens, 104 is a reflection mirror, 105 is a stimulable phosphor plate or sheet, and 106 is a stimulable phosphor plate or sheet. transport mechanism,
107 is a condenser of stimulated luminescent light (fiber array, etc.),
108 is a photoelectric converter such as a photomultiplier tube, 109 is an amplifier, 110 is an A/D converter, 111 is a frame memory, 112 is a memory such as a magnetic disk or optical disk, and 113 is an image processing section.

That is, the excitation light of the laser 101 is raster-scanned by an optical component such as a scanner 102 onto a moving stimulable phosphor plate or sheet 105, and a portion irradiated with the excitation light is scanned. Stimulated fluorescence is generated depending on the size of the latent image. The stimulated fluorescence is collected by a condenser 107, converted into a time-series electrical signal by a photoelectric converter 108, and A/D converted by an A/D converter 110, after which image information is sent to an image processing unit 113. sent as.

The above is an outline of a digital X-ray imaging system using a stimulable phosphor. This system uses a silver halide film (S/F method) sandwiched between conventional intensifying screens.
Compared to line images, it has advantages such as lower radiation exposure, fewer imaging errors, and the ability to process images.

[0016]

[Problem to be solved by the invention] Since it is a digital X-ray imaging system with such characteristics, it is naturally possible to use an X-ray imaging method that is different from the conventional direct silver halide film. There are cases in which an imaging method is used that is not at all advanced from the previous method.

That is, the same person's feet, hands, neck, head, etc.
When photographing small objects 2 multiple times, when using conventional silver halide film, cut into quarters, large-angle, etc.
For example, if you take a photo with your foot on the left side and a lead plate on the right side,
Next, place the same foot on the right side at a different angle, place a lead plate on the left side, take a picture, develop and fix it, and make two pieces of film.
It was displaying several X-ray images.

FIG. 6 is a diagram showing an example of imaging a plurality of subjects. For example, as shown in FIGS. c)
Obtaining an X-ray image as shown is a fairly frequently performed technique.

[0019] Such a split photographing method allows multiple images of the same person to be viewed in one photograph.
In addition to its basic purpose of making diagnosis easier, it has the advantage of saving film by allowing multiple shots to be taken with one film, and the advantage of completing the development and fixing process in one time. there were.

However, this method is time-consuming because the film position, subject position, and lead plate position must be carefully set in relation to the X-ray tube for each exposure, and more importantly, Although X-ray exposure to the film is avoided by using a lead plate, the influence of scattered X-rays from the subject cannot be avoided, and as a result, the image inevitably becomes unclear, which is a drawback that needs to be improved. It was rare.

On the other hand, a radiation image reading system using a stimulable phosphor plate or sheet 5 (see FIGS. 3 and 4)
In 1999, segmented photography was also carried out, but the method was similar to that of conventional silver-halide film, in which the subject 2 was placed on one part of a single photostimulable phosphor or sheet 5, and the other parts were photographed. 2 was shot separately by covering it with a lead plate, which took time and effort to shoot, and moreover, it was difficult to cover the subject with a lead plate.
Due to the influence of scattered X-rays from

[0022] The object of the present invention is to
Instead of so-called split shooting, in which a relatively small subject such as the neck is photographed multiple times on a single silver halide film or on a phosphorescent plate or sheet, it can be photographed on a single silver halide film in the same way. Although multiple radiographic images are obtained and the images are easy to diagnose, they do not require careful positioning during imaging, and are not affected by scattered X-rays from the subject during other imaging. The object of the present invention is to provide a radiation image capturing method that can obtain clear images.

[0023]

[Means for Solving the Problems] FIG. 1 is a diagram showing the basic configuration of the present invention. The above problems are solved by a radiation image capturing system configured as follows.

A photoelectric converter converts the stimulated luminescent light emitted by irradiating excitation light onto a photostimulable phosphor plate or sheet that absorbs a portion of the radiation energy that has passed through the subject and accumulates it as a latent image. In a radiographic imaging system that obtains image information as a signal and performs A/D conversion, multiple images are taken at the time of imaging, reading, or image processing, and there is a means for inputting the information.
At least a means for recognizing that multiple shots are taken during image processing 50, and displaying the reading results of each reading on a CRT and specifying (cropping) the effective subject area on the CRT screen, or displaying a digital image of the reading results. Recognizes the area where the subject of information exists and assigns a new address to only the effective subject area in advance according to the given silver halide film size, and if the new address of the effective subject area of multiple pieces of digital image information overlaps. Means for compositing images 51
,520,521,522,523,524,525
The radiographic images taken in multiple pieces can be captured in one
The images are composed so that they do not overlap each other on a sheet of silver halide film and are displayed on a hard copy or CRT screen.

[0025]

[Operation] The operation of these means will be explained below. In the present invention, a photoelectric converter converts the stimulated luminescent light emitted by irradiating excitation light onto a photostimulable phosphor plate or sheet that absorbs a portion of the radiation energy that has passed through the subject and accumulates it as a latent image. As an electric signal, A/
In radiographic imaging methods that obtain image information through D conversion, a photostimulated phosphor plate or sheet larger than the size of the subject is used.
The latent images taken multiple times are read using Then, using known image compositing technology, the multiple radiation images are combined onto a single silver halide film so that they do not overlap, and a hard copy is created.
, or displayed on one screen of a CRT.

[0026] To be more specific, the stimulable phosphor plate or sheet that absorbs a part of the radiation energy that has passed through the object and accumulates it as a latent image is emitted by irradiating excitation light with the stimulable phosphor plate or sheet. In a radiographic imaging system that converts emitted light into an electric signal using a photoelectric converter and converts it into an A/D signal to obtain image information, there is a means for inputting that multiple imaging is being performed at the time of imaging or at the time of reading, and a means for inputting multiple imaging at the time of at least reading. A means for recognizing that a photograph is being taken, a film size input in advance, and the reading results for each time are displayed on a CRT, and an effective subject area is specified on the CRT screen, or a digital image of the reading result is provided. Extracting the effective subject area obtained by determining the pixel value of each pixel in the radiographic image using a specific threshold, and giving a new address only to the extracted valid subject area, A means for compositing the plurality of radiographic images so that they do not overlap, and a means for hard copying the new composite image onto silver halide film and/or displaying it on a CRT were provided, and images were taken in multiple pieces. Radiographic image, 1
Images are synthesized on a sheet of silver halide film so that they do not overlap and are displayed on a hard copy or CRT screen.

That is, the point of the present invention is as shown in FIG.
, (b), instead of photographing without covering the parts not to be photographed with a lead plate, image information is obtained each time the photograph is taken, and the images are later combined using a known image processing technique to create the image shown in Figure 6 ( c.
) to make it into a single image. the result,
It is possible to omit careful alignment between the X-ray tube and the stimulable phosphor plate or sheet, and to eliminate the influence of scattered X-rays.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described in detail below with reference to the drawings. The above-mentioned FIG. 1 is a diagram showing the principle configuration of the present invention, and FIG. 2 is a diagram showing an embodiment of the present invention. Give an example, (c
) shows an example of image composition.

In the present invention, radiographic images taken in a plurality of pieces are combined onto a single silver halide film so that they do not overlap each other, and are printed as a hard copy or a CR.
The means 51 to 53 for displaying on the T screen are necessary means for carrying out the present invention. Note that the same reference numerals indicate the same objects throughout the figures.

The radiation image capturing system of the present invention will be explained below with reference to FIGS. 1 and 2. Generally, it is sufficient to use a stimulable phosphor plate or sheet 5 that matches the size of the subject, but the size of the subject is not necessarily determined. Therefore, the stimulable phosphor plate or sheet 5 used is of a size considerably larger than the subject 2.

[0031] Therefore, there is a lot of meaningless information in the image information obtained by reading the entire surface, and when multiple image information is displayed as a single silver halide film or CRT image, the information tends to protrude. Become.

For example, using a large-sized (35 cm square) photostimulable phosphor plate or sheet 5, take a photograph of the foot, read the entire surface, take the photograph twice, and combine the two images into a large-sized one. Even if you try to hard copy onto a large-sized film, it is impossible, and when reading it, only the part of the subject is read, or only the part of the subject is determined from the image information, and the part that does not have the subject is deleted, and the film is printed on a large-angle film. You must make sure that the two images fit within.

Therefore, in the present invention, during photographing, reading, or image processing, divided photographing is performed, and information such as the number of images, display order, etc., and information on which size of silver halide film to combine and in what order are specified.

[0034] The means of specification is as follows:
You can create a key for "divided shooting," or
Alternatively, the "split shooting mode" menu on the monitor screen may be selected.

When "divided shooting mode" is selected, a screen for specifying the subject (portion to be photographed), film size, etc. appears, and depending on the specifications (see processing step 51 in FIG. 1), image reading conditions or image Build a system so that processing conditions are automatically set.

Here, the image reading conditions are, for example, the width of the laser scan for reading the object part of the two radiation images shown in FIGS. 2(a) and 2(b). It means limiting the scanning direction) or time (distance in the sub-scanning direction), or specifying the number of image information to be captured. Specifically, it is a reading condition when the reading area is manually specified.

[0037] Also, the image processing conditions include, for example, in the above image information, if pixel values of almost the same value continue from the top, bottom, left, and right edges, or if the pixel values are below a specific threshold, the pixel values are passed through. This is the so-called reading condition for automatically reading a radiation image, in which image information of the necessary image area is obtained by recognizing that there is no subject. (See processing step 520 in FIG. 1) Based on the image information read based on the above conditions, a plurality of images, for example, two images in this embodiment, as shown in FIGS. image information, the silver halide film size specified above, and the hard copy device (radar).
In accordance with the specifications of the printer (a type of printer), it also instructs address conversion processing to combine the images so that they do not overlap each other. (See processing step 521 in FIG. 1) For example, in FIG.
When two digital images are taken and read independently, as shown in (a) and (b), the diagonally shaded areas on the left, right and bottom are clear areas and do not contain subject information. By deleting the information in the part and reading it, giving the read image a new address according to the silver halide film size and creating a composite image as shown in Figure 2 (c), Display two images. (Figure 1
Processing steps 521, 522, 523, 524, 5
(Refer to 3) When it is recognized in advance that the size of the silver halide film does not fit within the specified size during this synthesis process,
For example, a message is displayed on the display screen to indicate that composition is not possible.

[0038] When the message indicating that compositing is not possible is displayed, the operator manually changes the image reading conditions or image processing conditions. (Processing step 5 in Figure 1
(See No. 22, 524, 525) By doing so, there is an advantage that, for example, an image in which the toe of a foot is missing as shown in FIG. 6(c) is not required.

[0039] These image processing (the above processing steps)
520 to 525) can be done by data processing using a simple program.

[0040]

[Effects of the Invention] According to the present invention, the purpose of conventional segmented radiography is to display multiple images of the same person in one radiographic image, thereby making the image easier to diagnose. This eliminates the need to carefully align the X-ray tube, subject, and cassette (silver halide film) during imaging, which not only improves work efficiency, but also eliminates the need for shielding with a lead plate during conventional segmented imaging. This has the effect of eliminating the influence of scattered X-rays from the subject that could not be completely shielded, making it possible to obtain clear radiation images.

[Brief explanation of the drawing]

[Figure 1] Flowchart explaining the principle of the present invention

[Fig. 2] A diagram showing an embodiment of the present invention

[Figure 3] Diagram illustrating a radiation image capturing method using stimulable phosphor (Part 1)

[Figure 4] Diagram illustrating a radiation image capturing method using stimulable phosphor (Part 2)

[Fig. 5] Diagram showing an example of a schematic configuration of a reading section

[Figure 6] Diagram showing an example of imaging multiple subjects

[Explanation of symbols]

1 X-ray generation part
2 Subject 5 Photostimulated phosphor plate or sheet 6 Read-only device 7 Insertion part 9 for photostimulated phosphor plate or sheet
reading section
13 Image processing unit 101 Excitation light source (laser, etc.) 102 Scanner 105 Stimulated phosphor plate or sheet 107 Stimulated luminescent light collector 108 Photoelectric converter (photomultiplier tube) 1
10 A/D converter 113 Image processing section

Claims (2)

[Claims] Claim 1: A photoelectric converter converts the stimulated luminescent light emitted by irradiating excitation light onto a photostimulable phosphor plate or sheet that absorbs a portion of the radiation energy that has passed through the subject and accumulates it as a latent image. In a radiographic imaging method in which image information is obtained by A/D conversion into an electrical signal, a photostimulated phosphor plate or sheet larger than the size of the subject is used to read latent images taken multiple times, and at least: By combining images based on the silver halide film size and area information specified from each radiographic image area information taken in multiple images,
A radiographic imaging method characterized by hard copying a plurality of images onto a single silver halide film or displaying them on a single CRT screen. [Claim 2] A photoelectric converter converts the stimulated luminescent light emitted by irradiating excitation light onto a photostimulable phosphor plate or sheet that absorbs a portion of the radiation energy that has passed through the subject and accumulates it as a latent image. In a radiographic imaging system that obtains image information by converting it into an electrical signal and A/D converting it, there is a means for inputting that multiple imaging is being performed at the time of imaging or reading, and a means for recognizing that multiple imaging is being performed at least at the time of reading. means (50) for displaying each reading result on a CRT, specifying an effective subject area on the CRT screen, or recognizing the part of the subject in the digital image information of the reading result and providing it in advance; A means for assigning a new address to only the effective subject area according to the size of the silver halide film obtained, and compositing the plurality of digital image information into a single image so that the new addresses of the effective subject area overlap ( 51, 520, 521, 522, 523, 52
4,525), and combine the radiographic images taken in multiple pieces onto one silver halide film so that they do not overlap each other and make a hard copy, and or C
The radiation image capturing system according to claim 1, further comprising means (53) for displaying on the RT.