JPS5857735B2 - radiation detection film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes X
This invention relates to a film for direct line photography.

Film for direct X-ray photography (hereinafter referred to as X-ray film)
differs from ordinary photographic film in that it has a light-sensitive emulsion coating on both sides of the film base.

FIG. 1 is a cross-sectional view of a cassette containing an X-ray film and an intensifying screen during direct X-ray imaging.

In the figure, 1 is a film base and 2 is an emulsion coating.

An intensifying screen with a phosphor layer 3 coated on an intensifying screen substrate 4 made of paper or plastic film is placed in a cassette 5 with both sides of the film in close contact with each other as shown in the figure, and exposed to X-rays.

For convenience of explanation, let us now consider the case where one X-ray photon (represented by a dotted line 6 in the figure) passes through the cassette and causes the front sensitizing line phosphor to emit light.

The generated fluorescence sensitizes the area indicated by 8 of the front emulsion coating 2, but a portion of it is transmitted through the emulsion coating 2.

The base of conventional films is usually mixed with a blue organic colorant, which is equally transparent over almost the entire visible spectrum, making it a phosphor for intensifying screens. It is also transparent to the luminescence of calcium tungstate, and the luminescence that has passed through the emulsion coating 2 spreads through the film base as shown at 7, and passes through the emulsion coating 2 on the back side at 9. Expose over the indicated range.

For intensifying screens that require high sharpness, there are cases where a resolution of about 10 lines/frame is required, but the film base normally used has a thickness of about 200 μm, so compared to the photosensitive area 8. , the photosensitive area 9 has a considerable extent.

Even when X-rays cause the rear intensifying screen to emit light, a photosensitive area that is wider than the rear surface is generated in the front photoresist film in exactly the same way.

The inventor of the present invention used only the rear intensifying screen to perform imaging while varying the amount of X-ray irradiation. This was revealed from the results of measuring the photosensitivity of the film.

In order to eliminate the above-mentioned drawbacks, the present invention provides the film base with the ability to absorb the fluorescent light of an intensifying screen, thereby eliminating unnecessary light that passes through the base and improving the resolution of X-ray images. An improved X-ray film is provided.

FIG. 2 is a diagram for explaining the present invention in detail.

In the figure, curve 10 shows the emission spectrum of calcium tungstate, and curve 11 shows the transmittance of a conventional film base.

Curvature 12 indicates the transmittance of the film base colored orange; 2, which has the ability to absorb part of the fluorescent light.

According to the figure, the orange colored film base is approximately 5.
Light with wavelengths longer than 00 nm is transmitted, but light with wavelengths shorter than this is hardly transmitted.

Since the spectral sensitivity of the photosensitive emulsion is weak for light with a long wavelength of 500 nm or more, the above-mentioned problem does not occur.

In addition, in the case of a film that has spectral sensitivity up to the green region, which is made on the premise that a terbium-activated gadolinium oxysulfide (Cd202S:Tb) phosphor is used with an intensifying screen, the spectral sensitivity is around 550 nm from the short wavelength side. Terbium fluorescence can be absorbed by coloring with a dye that absorbs up to

In contrast, conventional film bases transmit light over the entire wavelength range, so they do not suffer from the above-mentioned drawbacks.

The present invention will be explained below by way of examples.

Example 1 FIG. 3 shows a film base using a 1 mrn color glass filter (one that removes light with a wavelength shorter than 500 nm) 13, and a photosensitive emulsion coating 2 provided on both sides of the filter 13. .

Intensifying screens were brought into close contact with both sides of the film, and measurements were taken using a microchart for resolution testing. As a result, an improvement of 6% in image sharpness was observed.

Example 2 Disperse dye with diazotizable amino groups, e.g. Fast Orange GC
, Disper Fast Orange R
se Fast Orange R) etc. to a thickness of 0.2
It is adsorbed onto the surface of the acetate film base between the layers, and then treated with a so-called color developer such as β-oxynaphthoic acid to form an azo dye layer on the film surface, resulting in transparency as shown in Figure 2. A photosensitive emulsion was coated on both sides to prepare an X-ray film.

Using the same test method as in Example 1, this film showed a sharpness change of 140% and a sensitivity ratio of 70% compared to conventional films.
%Met.

Example 3 Figure 4 shows C.I. Solvent Yellow 14 (
C, I, 5olvent Yellow 14),
Oil-Yellow Varnish Special (OiI Y
0.3% by weight of a dye such as yellow SS 5pesial) is mixed into the acetate film base material, dispersed sufficiently and uniformly, and then molded to form a film base 14, on which a photosensitive emulsion coating is applied. 2 was formed.

Figures 6 and 7 are C.I., respectively.

FIG. 3 is a diagram showing the relationship between transmittance and wavelength of Solvent Yellow 14 and Oil Yellow Varnish Special.

Although these dyes exhibit some transparency on the short wavelength side of 500 nm or less, this light does not cause any problems because it can be absorbed by the film base material or cut by selecting the thickness of the film.

Even when this film base was used, the same effects as in Example 2 were obtained.

Example 4 Figure 5 shows that the pigment described in Example 3 was mixed and
A photosensitive emulsion coating 2 is provided on a film base consisting of a film layer 14 having an ability to absorb fluorescence of nm or less and a normal film layer.

In this case as well, an improvement in image sharpness was observed. Example 5 30% by weight of C.I. Solvent Yellow 14 was dissolved and mixed in acetate, and the resulting mixture was sufficiently uniformly dispersed and applied onto an acetate film to form a colored thin film layer.A photosensitive emulsion was placed on the film base. A coating is provided to make an X-ray film.

This film also shows similar results to Example 2.

Example 6 Sudan I (5udan I) is coated on a film by the method shown in Example 5, the film base is colored reddish green, and then a photosensitive emulsion coating is applied to prepare an X-ray film.

When Cd2O2S:Tb was used as the intensifying screen, a 30% improvement in sharpness was obtained.

Example 7 The X-ray film shown in Example 2 was combined with a high-energy intensifying screen, and a γ-ray transmission image was taken using an artificial radioactive isotope (Tc99m) as a radiation source.

Good results were also obtained in this case.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a cassette used in an example of direct X-ray imaging, and Fig. 2 shows an example of the emission spectrum of calcium tungstate and the transmission spectra of conventional and inventive X-ray film bases. Curve diagram, Figure 3, Figure 4
5 are cross-sectional views of radiation detection films according to different embodiments of the present invention, and FIGS. 6 and 7 are curve diagrams showing transmission spectra of dyes used in the present invention. In the figure, 1: film base, 2: photosensitive emulsion coating, 3: phosphor layer, 4: intensifying screen substrate, 5: cassette, 6
: Incident radiation, 7: Fluorescent light traveling inside the base, 8: Sensitivity range of front emulsion layer, 9: Sensitivity range of rear emulsion layer, 13: Colored glass filter 14: Film base mixed with dye, 15: Conventional film base.

Claims (1)

[Claims] 1. A radiation detection film consisting of a light-transparent film and a pair of light-sensitive emulsion films formed on both sides of the film, and in which an intensifying screen is used in close contact with both light-sensitive emulsion films, wherein the light-transparent film is It is an orange light-transmissive film, and X-rays pass therethrough, but the light emitted from one of the intensifying screens passes through at least the light-transmissive film and reaches the surface of the light-transmissive film on the other intensifying screen side. 1. A radiation detection film characterized in that the photosensitive emulsion coating provided on the film is made of a material exhibiting light absorbing properties such that the photosensitive emulsion coating is not substantially exposed to light.