JPH03216600A - Manufacturing method for x-ray image conversion sheet - Google Patents

Abstract

PURPOSE:To eliminate scattering of a laser beam by an adhesive by forming a stimulated phosphorescent sheet on a transparent protection film with a prevention film for moisture permeation and then by adhering and fixing the stimulated phosphorescent sheet to the protection film on a carrier body, using an adhesive. CONSTITUTION:A stimulated phosphorescent film 1 is made to form a film under a protection film 3 by a doctor blade method and the stimulated phosphorescent film 1 is directly adhered to a carrier body 4, using an adhesive 5. In this case, compared to a conventional case where the stimulated phosphorescent film is taken out and is adhered to both the protection film and the carrier body, using two kinds of adhesives, scattering of a laser beam caused by the adhesive, is eliminated, as an adhesive between the protection film 3 and the stimulated phosphorescent film 1 is not required. Consequently, resolution can be improved.

Description

[Detailed Description of the Invention] rSummary] Regarding the X-ray image conversion sheet, the purpose of this is to put into practical use an X-ray image conversion sheet with improved image quality. The method for producing an X-ray image conversion sheet is characterized in that after forming the stimulable phosphor sheet, the stimulable phosphor sheet with the protective film is adhesively fixed onto a support using an adhesive. do.

[Industrial application field]

The present invention relates to a method for manufacturing an X-ray image conversion sheet.

The X-ray image conversion sheet constitutes an X-ray photography system in combination with a digital image processing device.

That is, although X-rays are used in a wide range of fields such as human body diagnosis and material identification, their greatest use is in X-ray diagnosis.

Diagnosis is performed using X-ray shadows and fluoroscopy, but since X-rays are radiation and are harmful to the human body, it is necessary to keep the exposure dose as low as possible. Improvements have been made to improve film sensitivity, and inspections can now be performed using an incomparably smaller amount of X-rays than in the past.

However, if you try to increase the sensitivity of the film, it is inevitable that the image quality will deteriorate.

On the other hand, recently developed X-ray photography systems use an X-ray image conversion sheet and a computer to process images. Specifically, they use an X-ray image conversion sheet instead of conventional film to take images. After converting the XL image imprinted onto the sheet into an electrical signal using a laser beam, this signal is processed by a computer, and this information is converted into the intensity of the laser beam to produce a normal photographic film. An X-ray photograph is created by transferring the images to

According to such a method, a clear image can be obtained with a dose that is several tenths or less compared to the conventional method.

In this way, the X-ray image conversion sheet is a sheet that uses a photostimulable phosphor as a photosensitive material, which can temporarily store radiation energy and then emit fluorescence again when excited by heat or light.

The present invention relates to a method for manufacturing such an X-ray image conversion sheet.

[Conventional technology]

The X-ray image conversion sheet is produced by firing a mixture of an alkaline earth metal halide and a eurobium halide in a reducing gas to create a divalent eurobium-activated halide alkaline earth metal phosphor. The phosphor is mixed with a binder and applied onto a base film, and a thin film of Mylar is adhered thereon using an adhesive to form a sheet.

Various studies have already been conducted on such photostimulable phosphors, and divalent eurobium-activated barium chloride bromide, represented by the following molecular formula, is known as an excellent photostimulable phosphor. .

(BaCj!Br+x A) :Eu""・(
1) However, A is GazOz+Y! 03+ GdzO:
Any one of + x < 0.02 Here, the principle of photostimulable fluorescence is that when a fluorescent crystal is irradiated with X-rays, electrons in the valence band move to the conduction band. Although it is excited, it immediately falls into the impurity level in the forbidden band and becomes stable.

This corresponds to the accumulation record of X-ray energy.

Next, when a laser beam is irradiated for reading, the electrons in the impurity level absorb the energy of the laser beam and are excited to the conduction electron band, and then fall back to the valence band, but at this time, the fluorescence is emitted. The body emits fluorescence, and its brightness is proportional to the amount of captured electrons in the impurity level.

Based on the above, the surface of the X-ray image conversion sheet is scanned with a tiny spot (100μll in diameter) of laser light, the fluorescent light emission of each pixel is detected using an interference filter, and then converted into an electronic signal using a photomultiplier tube. It is to be recorded.

A conventional method for manufacturing an X-ray image conversion sheet made of a photostimulable phosphor is to crush the photostimulable phosphor and then mix the stimulable phosphor with a binder (for example, polymethyl methacrylate (PMMA)) and a solvent. (e.g. toluene) to create a coating solution, and apply this to a fluororesin film (e.g. Teflon).
After the solvent is dried, the film is peeled off to form a stimulable phosphor film.

Next, as shown in FIG. 3, this photostimulable phosphor film 1 is pasted onto a protective film 3 made of polyethylene terephthalate (trade name Mylar) film or the like using an adhesive 2 such as epoxy resin. An X-ray image conversion sheet has been made and used by pasting it onto a support 4 made of glass or polyethylene terephthalate film using an adhesive 5 such as epoxy resin.

By using the X-ray image conversion sheet created in this way, image processing can now be performed using a much smaller amount of X-rays than in the past, but it is necessary to further improve image quality by improving resolution. there were.

[Problem to be solved by the invention] As mentioned earlier, the X-ray image conversion sheet constitutes an X-ray photography system in combination with a digital image processing device, and an X-ray image can be obtained with a small amount of X-rays. However, another challenge is to improve image quality.

[Means to solve the problem]

The above problem was solved by forming a photostimulable phosphor sheet on a transparent protective film with a moisture permeation prevention film, and then attaching the photostimulable phosphor sheet with the protective film to a support using an adhesive. This can be solved by configuring the method for manufacturing an X-ray image conversion sheet, characterized in that the sheet is fixed with adhesive.

[Effect]

X-ray images recorded on photostimulable phosphor film are read out by scanning with red to infrared laser light such as helium-neon (He-Ne) lasers or semiconductor lasers. However, the inventors noticed that the laser light was significantly scattered by the adhesive.

Therefore, as a method to eliminate this scattering, we decided to remove the adhesive 2 that adheres the stimulable phosphor film 1 and the protective film 3 in the conventional X-ray image conversion sheet configuration shown in FIG. It is something.

That is, conventionally, the photostimulable phosphor film was taken out,
In contrast to the conventional method of attaching protective film 3 and support 4 using adhesives 2 and 5, this method uses a doctor blade method to attach stimulable fluorescence to protective film 3, as shown in Figure 1. In this method, the stimulable phosphor film 1 is directly attached to the support 4 using an adhesive 5.

In this way, the protective film 3 and the stimulable phosphor film l
Since there is no need for an adhesive between the two, scattering of laser light by the adhesive is eliminated, and resolution can therefore be improved.

? Example] (BaCfBr+0.01 GazOi): Eu
30g of PMMA as a binder, 3g of dibutyl phthalate as a plasticizer, and 150g of toluene as a solvent were added to 500g of powder of photostimulable phosphor consisting of ``30g'' of powder, and the mixture was kneaded in a pole mill for 20 hours to form a paint. Had made.

On the other hand, indium oxide (InzO:+) with a thickness of 100
・Polyethylene terephthalate film with a thickness of 75μ on which tin oxide (SnO) is vapor-deposited as a moisture permeation prevention film (
A stimulable phosphor film was prepared by preparing a commercially available product and applying the previously prepared paint to a thickness of 250 μm using a doctor blade method.

Then, an epoxy resin was adhesively fixed onto a support made of glass having a thickness of 3.8 m, thereby completing an X-ray image conversion sheet.

This X-ray image conversion sheet and the conventionally structured X-ray image conversion sheet were each irradiated with 10 milli-roentgen (mR) of X-rays through a lattice made of a thin tungsten (W) plate to record information. A semiconductor laser (wavelength: 780 nm) was scanned to measure the relationship between rectangular wave response and spatial frequency.

FIG. 2 shows this relationship, and Example 6 to which the present invention is applied was able to improve the rectangular wave response by about 10% at 1 line bearer (LP/mm) compared to Conventional Example 7.

[Effects of the Invention] By carrying out the present invention, it is possible to eliminate scattering of laser light due to the adhesive, thereby making it possible to improve the quality of the detected image.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing the configuration of the X-ray image conversion sheet according to the present invention, Figure 2 is a relationship diagram between square wave response and spatial frequency, and Figure 3 is the configuration of a conventional X-ray image conversion sheet. This is a cross-sectional view. In the figure, 1 is a stimulable phosphor film, 2 and 5 are adhesives, 3 is a protective film, and 4 is a support.

Claims (1)

[Claims] After forming a photostimulable phosphor sheet on a transparent protective film with a moisture permeation prevention film attached, the photostimulable phosphor sheet with the protective film attached is fixed onto a support using an adhesive. A method for producing an X-ray image conversion sheet, characterized by: