JPH05224322A - X-ray image reader - Google Patents

Abstract

PURPOSE:To prevent the occurrence of an interference fringe and to obtain the sharp image of high-resolution by emitting laser beams with which an image converting part having a stimulable phosphor is irradiated from a light source for executing oscillation in a multi-mode. CONSTITUTION:This X-ray image reader 13 is composed of an image converting plate 21 as an image converting part receiving an X-ray image subjected to transmitting through a body to be measured 12, a semiconductor laser 22 as the light source emitting the laser beams 22a and executing the oscillation in the multi-mode, a galvanomirror 23 scanning the image converting plate 21 with the laser beams 22a, and for instance, an optical fiber bundle 24 converging fluorescence from the image converting plate 21. On the other hand, the image converting plate 21 is vertically moved by a prescribed driving mechanism. Beams outgoing from the optical fiber bundle 24 are received by an image processor 14, and prescribed image processing is executed. At this time, on the image converting plate 21, a phosphor layer is formed on the supporting body of a glass plate, and the protective film of the glass plate is laminated on the phospher layer by sticking.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray image reader for irradiating an X-ray image with laser light to read the image.

In recent years, digital radiography systems have been developed and used in place of medical X-ray photographs (screen films). This system reads an X-ray image picked up by an imaging plate coated with a stimulable phosphor with a laser beam, and improvement in image quality is desired.

[0003]

2. Description of the Related Art A conventional digital radiography system irradiates an object to be measured with X-rays, and images the object to be measured with an imaging plate coated with a stimulable phosphor (described later). A laser beam from a laser source performing single mode oscillation is scanned on the imaging plate, and an X-ray photograph is obtained by image processing.

In such a method, the X-ray dose is larger than that of the X-ray film (screen film) which has been conventionally used.
It is 1/2 to 1/20, and an image with good contrast can be obtained.

The imaging plate will be described below. As described above, the imaging plate is coated with a stimulable phosphor such as BaBr ₂ : Eu (barium bromide / europium).

BaBr ₂ : Eu which is a stimulable phosphor is
It is a phosphor having two functions of X-ray detection and memory. When irradiated with X-rays or ultraviolet rays, Eu, which is the emission center, is excited to emit blue light (photoluminescence). At the same time, some of the electrons in Eu are excited and captured in the color center. The color center is a Br ⁻ lattice defect, and the defect has a positive charge. Since the electrons are negatively charged, they are trapped in the color center, which is the memory function.

Next, when the photostimulable phosphor is irradiated with light of red or infrared wavelength, the electrons trapped in the color center are excited, and when they return to the Eu orbit, they emit blue light.
This is stimulated emission. This stimulated emission intensity is proportional to the intensity of X-rays. Therefore, an X-ray photograph can be obtained by converting this stimulated emission into an electric signal by a photomultiplier tube and performing image processing.

[0008]

By the way, in the imaging plate, a protective film is generally formed on the stimulable phosphor coated. On the other hand, since the reading laser light source oscillates in a single mode, there is a problem that the reflection of the surface of the protective film causes the laser light to interfere with each other and interference fringes appear in the image, which deteriorates the image.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide an X-ray image reading apparatus which obtains a clear image while preventing the occurrence of interference fringes.

[0010]

The above object is to receive an X-ray image obtained by irradiating an object to be measured with X-rays by an image conversion unit having a stimulable phosphor, and use the image conversion unit as a light source. In an X-ray image reading device that reads the X-ray image by fluorescence from the stimulable phosphor corresponding to the X-ray image by irradiating the laser light, the light source emits the laser light by multimode oscillation. It is solved by doing.

[0011]

As described above, the laser light for irradiating the image conversion section is irradiated by the light source for multimode oscillation. This multi-mode oscillation laser beam reduces the coherence of the laser beam on the surface of the image conversion unit and prevents the interference. This prevents the occurrence of interference fringes in the obtained read image, and makes it possible to obtain a clear high-resolution image.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a block diagram of an embodiment of the present invention.
FIG. 1 is composed of an X-ray generator 11, an object to be measured 12, an X-ray image reading device 13, and an image processing device 14.

The X-ray image reading device 13 includes an object 12 to be measured.
Image conversion plate 21 (which will be described later) that is an image conversion unit that receives an X-ray image that has transmitted through the semiconductor laser 2 that is a light source that emits laser light 22a and that performs multimode oscillation.
2, a galvano mirror 23 that scans the laser light 22a on the image conversion plate 21, and an optical fiber bundle 24 that collects the fluorescence from the image conversion plate 21, for example. The image conversion plate 21 moves up and down by a drive mechanism (not shown).

The light emitted from the optical fiber bundle 24 is received by the image processing device 14 and subjected to a predetermined image processing.

FIG. 2 is a block diagram of the image conversion plate shown in FIG. In FIG. 2, the image conversion plate 21
Is a glass plate with a thickness of 300 μm (resin plate may be used)
A phosphor layer 32 is formed on a support (protective film) 31 of
On the phosphor layer 32, for example, a protective film 33 of a glass plate having a thickness of 300 μm is laminated by adhesion.

The phosphor layer 32 contains, for example, a stimulable phosphor, a resin binder, a solvent and a plasticizer in a weight ratio of 100: 60: 30 :.
6 was mixed and formed by the doctor blade method. As the stimulable phosphor, BaBr ₂ : Eu, BaC
lBr: Eu or the like can be used. As a resin binder,
Acrylic resin, polyester resin, cellulose resin and the like can be used. A solvent that can dissolve the resin binder is used, and acetone, toluene, MEK, or the like is used. Dibutyl phthalate is used as the plasticizer.

FIG. 3 shows a spectrum distribution diagram of oscillation modes of the light source shown in FIG. As shown in FIG. 3A, the semiconductor laser 22 as a light source in FIG. 1 oscillates in a longitudinal mode multi, and emits a laser beam 22a. Incidentally, FIG. 3 (B) shows a spectrum oscillated in a single mode conventionally used.

The X-ray image reading device 13 as described above uses
The X-rays emitted from the line generator 11 pass through the DUT 12 and enter the image conversion plate 21. As described above, in the image conversion plate 21, Eu, which is the emission center, is excited by X-rays to emit blue light, and at the same time, electrons are excited in a part of Eu and are captured in the color center. Then, the image conversion plate 21 is moved downward.

On the other hand, a laser beam 22a is emitted from the semiconductor laser 22 which oscillates in the multimode, and the image conversion plate 21 is scanned by the galvanometer mirror 23.

When the image conversion plate 21 is irradiated with the laser beam 22a, the electrons trapped in the color centers are excited and emit blue light when returning to the Eu orbit as described above.
The stimulated emission intensity at this time is proportional to the X-ray intensity. This is condensed by the optical fiber bundle 24 and is received by the image processing device 14.

Then, in the image processing device 14, the stimulated emission is converted into an electric signal by a photomultiplier tube and image-processed to obtain an X-ray photograph.

As described above, by using the semiconductor laser 22 which performs multi-mode oscillation, interference fringes due to reflection on the protective film 33 of the image conversion plate 21 do not occur on a photographed image, and a clear high resolution is obtained. Images can be obtained. By the way, when an image is taken using a single mode oscillation semiconductor laser, interference fringes having a maximum size of 10% are observed.

In the above embodiment, the case where the light source is a multi-mode oscillation semiconductor laser is shown. However, a multi-mode oscillation He-Ne laser may be used, and in this case, light emission is caused by the difference in wavelength. The colors are different.

[0024]

As described above, according to the present invention, a laser beam for irradiating the image conversion portion having a stimulable phosphor is emitted from a light source that performs multi-mode oscillation, so that a read image can be obtained. It is possible to prevent the occurrence of interference fringes,
A clear high-resolution image can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram of the image conversion plate of FIG.

FIG. 3 is a spectrum diagram of an oscillation mode of the light source of FIG.

[Explanation of symbols]

 11 X-ray generator 12 Object to be measured 13 X-ray image reading device 14 Image processing device 21 Image conversion plate 22 Semiconductor laser 22a Laser light 23 Galvano mirror 24 Optical fiber bundle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masami Hasegawa 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Soichiro Hidaka, 1015, Kamikodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited

Claims (2)

[Claims] 1. An X-ray image obtained by irradiating an object to be measured (12) with X-rays is converted into an image conversion unit (2) having a stimulable phosphor.
In 1), the image conversion section (21) is irradiated with a laser beam (22a) from a light source (22), and the X-ray image is generated by fluorescence from the stimulable phosphor corresponding to the X-ray image. An X-ray image reading device for reading, wherein the light source (22) emits the laser light (22a) by multi-mode oscillation. 2. The X-ray image reading apparatus according to claim 1, wherein the light source is constituted by a semiconductor laser (22).